Arctic Sea Ice : Forum

Cryosphere => Greenland and Arctic Circle => Topic started by: Sigmetnow on March 31, 2013, 01:02:14 AM

Title: The Nares Strait thread
Post by: Sigmetnow on March 31, 2013, 01:02:14 AM
The perennial question: when will the Nares Strait ice bridge break up?

Here’s a teaser: looks like the Navy HYCOM ice thickness maps show mass movement there next week.  Run 3/28/2013, valid 3/29 to 4/5.

See if this one plays out!
Title: Re: The Nares Strait thread
Post by: gfwellman on March 31, 2013, 04:31:06 AM
In the visible spectrum, the Northwater Polynya is pretty large this year and reaches well into Kane Basin.  So I'd expect the basin to break up easily in response to strong currents or a strong tide.  But Nares north of the basin can hold on longer - what were the temperatures like over the winter in that area (relative to normal)?
Title: Re: The Nares Strait thread
Post by: Neven on March 31, 2013, 07:29:16 PM
This is a great subject for a thread! Even though - correct me if I'm wrong - Nares can only constitute 10% of the transport that Fram is capable of, its arches are to me still one of the most fascinating things to watch in the Arctic. I always reserve a blog post for their collapse.

As a primer I recommend this piece by Patrick Lockerby, the first blogger to actively start writing about the Arctic: The Broken Bridges of Nares (http://www.science20.com/chatter_box/arctic_tipping_points_4_broken_bridges_nares).

Here's my post (http://neven1.typepad.com/blog/2011/06/nares-bridge-is-falling-down.html) on the collapse on June 17th 2011. And last year (http://neven1.typepad.com/blog/2012/06/nares-strait-2012-ice-arch-collapsing.html) on June 27th. Here's the first animation (http://neven1.typepad.com/blog/2010/06/nares-strait-animation-part-1.html) I made of Nares Strait on June 14th 2010 (no arches that year if I remember correctly).

And don't miss out on Andreas Münchow's blog, as he is a true Nares expert: Icy Seas (http://icyseas.org/)
Title: Re: The Nares Strait thread
Post by: Sigmetnow on April 01, 2013, 07:49:26 PM
Here we are as of March 31, 2013.  One floe recently broken off; the nearby edge irregularities look ready to go.  No visible cracks, but lots of shadows in the ice in the center-right of the pic.
Title: Re: The Nares Strait thread
Post by: Andreas Muenchow on April 01, 2013, 10:21:17 PM
The ice-bridge of Nares Strait will probably no collapse until mid-June as that's what it usually does. It formed much earlier this winter and had more time to become consolidated from when it formed back in November or so. Its current location is indeed farther north and, I believe, perhaps relates to the grounded Petermann Ice Island that formed in July 2012. With the sun low in the south, you can see the shadow that the freeboard if the ice-island casts in the north-eastern quadrant of the ice-bridge.

Good fun to watch and puzzle over what is happening up there, I could not agree more and post weekly re-processed, geo-located mappings of Nares Strait MODIS imagery. If anyone wants the ascii data in columns of latitude, longitude, band-1, band-2, ..., band-36 for any particular day or scene, let me know and I put it up for your pleasure  ;)
Title: Re: The Nares Strait thread
Post by: Espen on April 01, 2013, 10:58:48 PM
Hi Andreas,

And welcome to a new season!

I very much doubt the ice-bridge will last until mid-June.

Yes when looking at the 250 m Modis, there is something looking like the Petermann Ice Island, I thought it "stranded" much closer to the shores of Nares, it is placed almost in the middle of the Strait.it can be watched at todays image:
http://rapidfire.sci.gsfc.nasa.gov/imagery/subsets/?subset=Arctic_r03c02.2013091.terra.250m (http://rapidfire.sci.gsfc.nasa.gov/imagery/subsets/?subset=Arctic_r03c02.2013091.terra.250m)

Title: Re: The Nares Strait thread
Post by: TerryM on April 03, 2013, 06:14:51 PM
PII2012-A-1 was still moving up to 9/10/2012 when winter darkness overtook MODIS. The main body of it was still north of where the deep, rounded shadow is now being cast. There was a section breaking off on that date that is visible in MODIS or Arctic.io's split zoom, but it was the furthest north corner.


Setting the split zoom to the 9th of Oct will show that the small shadow portion close to the ice bridge may be of a section split from PII2012-A-1 at an earlier date. There is a larger, less well defined shadow north east of the more circular one that may indicate the present edge of the ice island. If so it indicates that the ice island was still moving and rotating after 9/10.


It's much easier to follow with the split zoom than to post an animation, or a series of photos here.


For anyone new to Nares Strait or interested in Petermann Ice Island Andreas's Icy Seas Blog is a must read.


Terry




Title: Re: The Nares Strait thread
Post by: Jim Hunt on April 06, 2013, 12:55:05 PM
Yesterday's view of the area from Terra. See NASA Worldview (http://earthdata.nasa.gov/labs/worldview/?map=-1718592,-640256,-763712,-128768&products=baselayers.MODIS_Terra_CorrectedReflectance_TrueColor~overlays.arctic_coastlines&time=2013-04-05T12:00:00&switch=arctic) for a closer look.

Notice any difference from Espen's view on the first of April, or Sigmetnow's on the last of March? Try following the coast down towards Disko.
Title: Re: The Nares Strait thread
Post by: Sigmetnow on April 06, 2013, 03:54:22 PM
Is it just me, or is the ice looking thinner north (to the right, in this pic) of the open water in the strait?

Here’s a link to the DMI images:
http://ocean.dmi.dk/arctic/kane.php (http://ocean.dmi.dk/arctic/kane.php)

The  "05-04-2013 [TERRA]"   and   "05-04-2013 [AQUA]"  images look particularly suggestive.  (If one can say that about ice.)
Title: Re: The Nares Strait thread
Post by: Espen on April 06, 2013, 05:52:31 PM
Sigmetnow;

Yes there are traces of melting in the surface of snow/ice, at least there are some dark spots /shades that indicate that.

You also see indications of melt at the southern faced slopes of Washington Land.
Title: Re: The Nares Strait thread
Post by: Espen on April 17, 2013, 05:01:13 PM
Ice Break up;

Soon there will be a new open water spot, just south of Kap Jefferson (Washington Land) a hole appears in the ice:

http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2013107105500-2013107110000.250m.jpg (http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2013107105500-2013107110000.250m.jpg)
Title: Re: The Nares Strait thread
Post by: Sigmetnow on April 22, 2013, 03:22:26 PM
Even though Nares Strait may not have changed markedly from a visual standpoint in recent days, I thought it would be good to record the rather striking Navy HYCOM ice thickness graphic changes.  This is from April 1 to April 20 (missing April 16).
Title: Re: The Nares Strait thread
Post by: FrankD on April 23, 2013, 01:10:00 PM
Perhaps I'm misunderstanding you Espen, but the only obvious seperate patch of open water isn't in Nares Strait, it's in Cardigan Strait/Fram Sound, the narrowest stretch of water between Devon Island and Ellesmere Island.

It appears every year at about this time, ahead of the gradual clearing of Ice from Jones Sound. I haven't checked whether its bigger or earlier this year, but its a regular feature.

Perhaps I'm missing something, but I think you've got turned around.
Title: Re: The Nares Strait thread
Post by: Espen on May 06, 2013, 06:28:14 PM
We will soon a breakthrough in the ice of Cap / Kap  Jackson just south of Washington Land:

https://mapsengine.google.com/map/edit?mid=zbdKKg4fRHYo.kjkUmepfXc9A (https://mapsengine.google.com/map/edit?mid=zbdKKg4fRHYo.kjkUmepfXc9A)

Can be seen today's Modis image : http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2013126130500-2013126131000.250m.jpg (http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2013126130500-2013126131000.250m.jpg)

Title: Re: The Nares Strait thread
Post by: Peter Ellis on May 07, 2013, 01:33:20 AM
Are you sure you're reading that right?  The ice arch is currently far south of that, and the small ice breakup on that Rapidfire image is in the vicinity of Kap Inglefield / Caim Pynt.
Title: Re: The Nares Strait thread
Post by: Mike Fliss on May 07, 2013, 07:15:24 AM
Yes, Espen is correct.  There are 2 pinpoints of open water off the cape.  A polynya frequently opens in that area. 
Title: Re: The Nares Strait thread
Post by: Espen on May 09, 2013, 07:51:36 PM
The pinpoints of Kap Jackson (Washington Land) are developing and the sea ice and snow cover in the mouth of Petermann Fjord is getting thinner (melting/blue):

http://rapidfire.sci.gsfc.nasa.gov/imagery/subsets/?subset=Arctic_r03c03.2013129.aqua.250m (http://rapidfire.sci.gsfc.nasa.gov/imagery/subsets/?subset=Arctic_r03c03.2013129.aqua.250m)
Title: Re: The Nares Strait thread
Post by: Sigmetnow on May 13, 2013, 03:19:47 PM
Open water now extends the full width of the strait.

http://earthdata.nasa.gov/labs/worldview/?map=-1417184,-539712,-814048,-129088&products=baselayers,MODIS_Terra_CorrectedReflectance_TrueColor~overlays,arctic_coastlines&time=2013-05-12&switch=arctic (http://earthdata.nasa.gov/labs/worldview/?map=-1417184,-539712,-814048,-129088&products=baselayers,MODIS_Terra_CorrectedReflectance_TrueColor~overlays,arctic_coastlines&time=2013-05-12&switch=arctic)
Title: Re: The Nares Strait thread
Post by: Espen on May 24, 2013, 04:03:12 PM
For those thirsty? A decent watering hole is appearing of Kap Jackson (Washington Land) 8):

http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2013144093500-2013144094000.500m.jpg (http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2013144093500-2013144094000.500m.jpg)
Title: Re: The Nares Strait thread
Post by: TerryM on May 25, 2013, 07:50:45 PM
Using the Arctic.io Split Zoom feature I was amazed at how few changes have taken place in Nares over the last month.


Terry
Title: Re: The Nares Strait thread
Post by: Espen on May 25, 2013, 08:13:59 PM
Terry;

Nothing much except for the Nite Owls ;)
Title: Re: The Nares Strait thread
Post by: Peter Ellis on June 09, 2013, 10:40:44 AM
Pretty cold up there - in fact there's been substantial refreezing downstream of the Nares ice arch in the last few days!

3rd April: see the arch about 1/4 of the way down the right hand edge of the tile
http://rapidfire.sci.gsfc.nasa.gov/imagery/subsets/?subset=Arctic_r03c02.2013154.terra.1km (http://rapidfire.sci.gsfc.nasa.gov/imagery/subsets/?subset=Arctic_r03c02.2013154.terra.1km)

8th April: the arch is "filling in" with new ice
http://rapidfire.sci.gsfc.nasa.gov/imagery/subsets/?subset=Arctic_r03c02.2013159.terra (http://rapidfire.sci.gsfc.nasa.gov/imagery/subsets/?subset=Arctic_r03c02.2013159.terra)
Title: Re: The Nares Strait thread
Post by: TerryM on June 09, 2013, 06:26:02 PM
Peter


I don't remember seeing anything similar in past years. Wonder if PII2012 could be involved ? The reversed ice arch in the Lincoln Sea is also unusual.


Terry
Title: Re: The Nares Strait thread
Post by: icebgone on June 09, 2013, 11:56:23 PM
I was counting on the Nares to be open for business by the end of June.  Right now it looks as solid as stone.  Until the Nares breaks there is going to be continued thickening of ice in the Beaufort and the CAA.
Title: Re: The Nares Strait thread
Post by: Peter Ellis on June 10, 2013, 12:31:59 AM
I was counting on the Nares to be open for business by the end of June.  Right now it looks as solid as stone.  Until the Nares breaks there is going to be continued thickening of ice in the Beaufort and the CAA.
Huh? Nares bridge is one of the more resilient features in the area.  Even last year it held on until June 26th, by which point melt in the CAA and Beaufort was well underway.  A broken bridge at Nares has some significance, but not that much - it drains about 1/10 as much ice as Fram strait, and export is only a small fraction of total ice loss.  I'd be surprised if the presence/absence of a bridge at Nares during June affects the summer minimum by more than 1%.
Title: Re: The Nares Strait thread
Post by: Espen on June 10, 2013, 11:10:51 AM
A few more watering holes are opening in the Kennedy Channel area:

http://rapidfire.sci.gsfc.nasa.gov/imagery/subsets/?subset=Arctic_r03c03.2013160.aqua.250m (http://rapidfire.sci.gsfc.nasa.gov/imagery/subsets/?subset=Arctic_r03c03.2013160.aqua.250m)
Title: Re: The Nares Strait thread
Post by: Whit on June 10, 2013, 12:02:04 PM
The break-up in the Lincoln-Sea is quite interesting. (http://earthdata.nasa.gov/labs/worldview/?map=-432576,-890496,159296,-497280&products=baselayers,MODIS_Terra_CorrectedReflectance_TrueColor~overlays,arctic_coastlines_3413&time=2013-06-09&switch=arctic) It seems like the ice there is much more vulnerable than last season.
Title: Re: The Nares Strait thread
Post by: Shared Humanity on June 11, 2013, 12:03:13 AM
The break-up in the Lincoln-Sea is quite interesting. (http://earthdata.nasa.gov/labs/worldview/?map=-432576,-890496,159296,-497280&products=baselayers,MODIS_Terra_CorrectedReflectance_TrueColor~overlays,arctic_coastlines_3413&time=2013-06-09&switch=arctic) It seems like the ice there is much more vulnerable than last season.

Isn't this some of the thickest MYI?
Title: Re: The Nares Strait thread
Post by: Espen on June 11, 2013, 04:21:13 PM
Peter


I don't remember seeing anything similar in past years. Wonder if PII2012 could be involved ? The reversed ice arch in the Lincoln Sea is also unusual.


Terry

Terry;

I dont think PII2012 is involved, if so, very limited although is a nice big piece of ice, it is small compared to the rest of the scene.
Title: Re: The Nares Strait thread
Post by: TerryM on June 11, 2013, 05:41:07 PM
Espen


I was thinking more of the fact that it is grounded & could provide an anchoring point for the ice arch rather than the size of the ice island.
It will be interesting to see if it survives the season. There's a lot of relatively warm water rushing past but it is a big cube to melt.


Terry
Title: Re: The Nares Strait thread
Post by: Espen on June 11, 2013, 05:46:10 PM
Terry;

If it stays, it will last a few seasons, if it drifts south, depending where, it may only last another 2 years. It still a lot of ice to melt/evaporate.
Title: Re: The Nares Strait thread
Post by: TerryM on June 21, 2013, 07:22:24 PM
A***'s split zooms are coming into their own now that we can split back a full year. The ice bridge is further north than last year and seems to be showing some action over the last 3 days. PII2012 hasn't moved as of yet according to it's beacon, but the ice nearby is peeling away.


Terry
Title: Re: The Nares Strait thread
Post by: anonymous on June 21, 2013, 09:04:52 PM
Actually 3 years: arctic.io/split-zoom/2010-06-20;2013-06-20 (http://www.arctic.io/split-zoom/2010-06-20;2013-06-20/0.405100104;0.533628460;5.981244165/Nares-Strait) ;)
Title: Re: The Nares Strait thread
Post by: TerryM on June 21, 2013, 09:35:45 PM
Actually 3 years: arctic.io/split-zoom/2010-06-20;2013-06-20 (http://www.arctic.io/split-zoom/2010-06-20;2013-06-20/0.405100104;0.533628460;5.981244165/Nares-Strait) ;)
I'm now counting 4 years, but regardless it's a marvelous tool you've provided for those of us interested in comparing the minutia from year to year. The ability to detect slight movements that are otherwise so easy to miss is great for verifying fast ice that's not quite fast anymore & the capacity to split back a year (or more) gives a good indication of how far we're ahead, or behind previous melt seasons.
My country (Canada) is attempting to keep knowledge of Arctic changes hidden away from the public. It's wonderful to see how through the efforts of people like yourself, Neven and Andreas these efforts have failed.
Terry
Title: Re: The Nares Strait thread
Post by: Laurent on June 26, 2013, 04:31:47 PM
Espen is that open water near Nares strait ? Look like it !
Temps are high in the area ! (above zero)
http://weather.gc.ca/forecast/canada/index_e.html?id=NU (http://weather.gc.ca/forecast/canada/index_e.html?id=NU)
Title: Re: The Nares Strait thread
Post by: Espen on June 26, 2013, 05:02:12 PM
Laurent,

No, but soon to be, give it a week or two!
It is Archer Fjord, with Beatrix Bay in the left end and to the right you have Lady Franklin Bay/ Hall Bassin/ Nares Strait the peninsula is Judge Daly Promontory a part of Ellesmere Island.

And to the right of that red circle you find the natural harbour "Discovery Harbour" used as winter station for the Discovery Expedition (George Strong Nares)

Discovery Harbour:  https://maps.google.com/maps?output=classic&daddr=Discovery+Harbour+%4081.69784444971418,-65.467529296875
Title: Re: The Nares Strait thread
Post by: Lynn Shwadchuck on June 26, 2013, 05:12:21 PM
My country (Canada) is attempting to keep knowledge of Arctic changes hidden away from the public. It's wonderful to see how through the efforts of people like yourself, Neven and Andreas these efforts have failed.

As a fellow Canadian, Terry, I'm totally bummed now that I've looked up the Nares Strait and found this Environment Canada page supposedly updated in 2012, but the latest image is from 2009.

http://www.ec.gc.ca/glaces-ice/?lang=En&n=3D5398F0-1 (http://www.ec.gc.ca/glaces-ice/?lang=En&n=3D5398F0-1)
Title: Re: The Nares Strait thread
Post by: Espen on June 27, 2013, 04:18:19 PM
On today's swath image from Modis, there appears a crack across Robeson Channel / Nares Strait from Newmann Bugt / Kap Brevoort / Nyboe Land across to Wrangel Bay/ Ellesmere Island, maybe the first serious sign of break up in the Strait?

http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2013178110000-2013178110500.250m.jpg (http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2013178110000-2013178110500.250m.jpg)
Title: Re: The Nares Strait thread
Post by: Andreas Muenchow on June 27, 2013, 05:48:12 PM
My country (Canada) is attempting to keep knowledge of Arctic changes hidden away from the public. It's wonderful to see how through the efforts of people like yourself, Neven and Andreas these efforts have failed.

As a fellow Canadian, Terry, I'm totally bummed now that I've looked up the Nares Strait and found this Environment Canada page supposedly updated in 2012, but the latest image is from 2009.

http://www.ec.gc.ca/glaces-ice/?lang=En&n=3D5398F0-1 (http://www.ec.gc.ca/glaces-ice/?lang=En&n=3D5398F0-1)
Canadians have been VERY active in Nares Strait sending the CCGS Henry Larsen up in 2006, 2007, 2009, and most recently in 2012. Rick Mercer nicely sums up the current malaise in this funny political commentary and/or comedy

http://www.cbc.ca/player/Shows/Shows/The%20Rick%20Mercer%20Report/ID/2339221059/ (http://www.cbc.ca/player/Shows/Shows/The%20Rick%20Mercer%20Report/ID/2339221059/)

And the Nares Strait ice-bridge will break up very soon as the ice warms from the surface and land losing its structural integrity with regard to both vertical and lateral stresses that will lead to failure and collapse of the bridge. Always fun to anticipate and watch, very hard to model and predict.


Title: Re: The Nares Strait thread
Post by: TerryM on June 27, 2013, 10:04:21 PM
Having survived the super spring tide on the 23d, my WAG is that we'll have to wait until after the July 7 spring tide before we see too much action. If the recent rains at Mittarfik Qaanaaq move over the icebridge all bets are off.


I've been using the Kap Morris Jesup tide tables but wonder if there are locations in or at least closer to Nares Strait that post actual tidal information?


Terry
Title: Re: The Nares Strait thread
Post by: Andreas Muenchow on June 28, 2013, 07:34:56 AM
I can post tidal predictions from either side of southern Nares Strait for Alexandra Fjord on Ellesmere and Foulke Fjord on Greenland from successful bottom pressure measurements for the 2003-12 and 2003-06 periods, respectively. The Morris Jesup (or Alert) tidal records are  good only for general neap/spring occurence, but not for much else. The tide varies dramatically along Nares Strait as Kane Basin is resonating at the semi-diurnal tide and the weak forcing from the north is interacting with the much stronger forcing from the south leading to wicked and large phase variations. Tidal currents are different yet again as friction, capes, headlands, and lots of small scale feature determine the dynamic response. Think of the tidal elevation (sea level) as the averaged (integrated) large scale effect of all those tidal velocities that vary at small scales.

Petermann's 2012 ice island becomes visible in MODIS as well, even its central channel shows in high-res imagery with a little squinting.
Title: Re: The Nares Strait thread
Post by: Espen on June 28, 2013, 01:45:28 PM
My country (Canada) is attempting to keep knowledge of Arctic changes hidden away from the public. It's wonderful to see how through the efforts of people like yourself, Neven and Andreas these efforts have failed.

As a fellow Canadian, Terry, I'm totally bummed now that I've looked up the Nares Strait and found this Environment Canada page supposedly updated in 2012, but the latest image is from 2009.

http://www.ec.gc.ca/glaces-ice/?lang=En&n=3D5398F0-1 (http://www.ec.gc.ca/glaces-ice/?lang=En&n=3D5398F0-1)
Canadians have been VERY active in Nares Strait sending the CCGS Henry Larsen up in 2006, 2007, 2009, and most recently in 2012. Rick Mercer nicely sums up the current malaise in this funny political commentary and/or comedy

http://www.cbc.ca/player/Shows/Shows/The%20Rick%20Mercer%20Report/ID/2339221059/ (http://www.cbc.ca/player/Shows/Shows/The%20Rick%20Mercer%20Report/ID/2339221059/)

And the Nares Strait ice-bridge will break up very soon as the ice warms from the surface and land losing its structural integrity with regard to both vertical and lateral stresses that will lead to failure and collapse of the bridge. Always fun to anticipate and watch, very hard to model and predict.

Just to add to Andreas comments, on this following image the release of the ice stuck along the rocks of Nares Strait, more and more open water areas are seen. And soon the ice will break up, give it another week, or so.
Title: Re: The Nares Strait thread
Post by: TerryM on June 29, 2013, 02:26:45 PM
Thanks for the offer Andreas, but my understanding doesn't go much further than observing that fast ice sometimes appears susceptible to spring tides. With PII2012 so close to the edge we should find out soon whether it's floating of still stuck in the mud.


This recent proxigean tide might have lifted it out, assuming that it is stuck, had it not been trapped by the other ice. Do you think that all the months of water rushing be the keel will have reduced it sufficiently for it to float on out of Kane Basin?


Terry


Title: Re: The Nares Strait thread
Post by: Patrick on July 03, 2013, 11:54:30 PM
...

And the Nares Strait ice-bridge will break up very soon as the ice warms from the surface and land losing its structural integrity with regard to both vertical and lateral stresses that will lead to failure and collapse of the bridge. Always fun to anticipate and watch, very hard to model and predict.
From today's Terra/MODIS imagery it seems like the ice arch is now beginning to break up...

Image Source: NASA Worldview (http://earthdata.nasa.gov/labs/worldview/?map=-663296,-1176832,-421120,-939776&products=baselayers,MODIS_Terra_CorrectedReflectance_TrueColor~overlays&time=2013-07-03&switch=arctic)
Title: Re: The Nares Strait thread
Post by: Espen on July 04, 2013, 08:09:39 AM
Patrick,

Yes and we have more cracks inside Kennedy Channel / Nares Strait in the vicinity of Franklin Island and Crozier Island:
Title: Re: The Nares Strait thread
Post by: TerryM on July 04, 2013, 09:45:45 PM
The ice bridge edge is toast, at least on the eastern side. The image is better in aqua than terra but still some unfortunate clouds. PII2012-A-1 doesn't seem to have moved, but it's very hard to see.


Terry
Title: Re: The Nares Strait thread
Post by: Espen on July 06, 2013, 02:17:00 PM
Recent cracking near Franklin Island:
Title: Re: The Nares Strait thread
Post by: Espen on July 07, 2013, 09:23:45 PM
Only days away from the ice collapse in Nares Strait:
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 07, 2013, 10:36:08 PM
The arch is now to the leading edge of the Petermann Ice Island.  Some have suggested it is grounded.  We will soon find out.

A year or two ago, I compared pictures of the iced over Kane Basin and could detect movement in the various floes even before the bridge broke.  I did not detect similar movement this year, although I only checked on one recent week.
Title: Re: The Nares Strait thread
Post by: Espen on July 08, 2013, 12:37:45 PM
As suggested yesterday, the cracking and collapse of the sea ice in Nares Strait is now in progress, cracks are now seen on the prelim. Modis swath images crisscrossing both Kane basin and Nares Strait / Kennedy Channel, the resolution from the swath image is not as good wanted but it will upgraded later today:



 
Title: Re: The Nares Strait thread
Post by: Espen on July 10, 2013, 09:42:53 AM
Only hours or few days away from the Grand Opening of Nares Strait:

Title: Re: The Nares Strait thread
Post by: Espen on July 10, 2013, 02:24:25 PM
July 10 2013 later:
Title: Re: The Nares Strait thread
Post by: Espen on July 10, 2013, 08:10:19 PM
Break up is on the way.

Click on image to enlarge!
Title: Re: The Nares Strait thread
Post by: Espen on July 11, 2013, 07:40:18 AM
The Nares Express is ready to leave:

Title: Re: The Nares Strait thread
Post by: Neven on July 11, 2013, 07:55:21 AM
Thanks for the update and image, Espen! I have just written a post for the ASIB that will be published tonight.
Title: Re: The Nares Strait thread
Post by: Espen on July 11, 2013, 11:11:25 AM
Watching the disintegration of sea ice in Nares Strait over the last couple of days, I realize I was probably wrong when stating earlier to Terry that P2-2012 had no influence on the break up of sea ice in the Strait.
I now see that P2-2012 is actually sitting far more in the center of the Strait than I thought, and to me it is now clear it is to some extend blocking the ice from moving south thru Smith Sound and Baffin Bay.

The yellow spot spot on image below is P2/2012.
Title: Re: The Nares Strait thread
Post by: Espen on July 11, 2013, 03:18:56 PM
Latest image from Nares Strait / Kane Basin:
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 11, 2013, 03:59:51 PM
A bathymetric map of Nares Strait is at http://icyseas.org/2012/09/02/petermann-ice-island-2012-breaking-up/ (http://icyseas.org/2012/09/02/petermann-ice-island-2012-breaking-up/).  From this article, the Petermann Ice Island was (is?) about 144 meters thick.  It clearly remains grounded, as it has not moved since last (northern hemisphere) autumn (even as the ice around it breaks up and floats southward).  The ice island appears to be stuck about where the tiny 100 m contour (just a point on the map) is.
Title: Re: The Nares Strait thread
Post by: TerryM on July 11, 2013, 07:14:20 PM
I'm seeing a very small movement south for PII2012-A-1 using Arctic.io's split zoom. Todays images still aren't up yet so I've been comparing 7-7 to 7-10.
It's certainly moving much slower than the surrounding ice and may actually be rotating slightly rather than moving southward so I assume the keel is grounded to some extent. It wasn't enough to maintain the ice bridge but it may have kept it in place for one tide cycle.
If it did maintain the ice bridge for an additional 14 days, that could have an effect on the Sept. minimum.
We won't have another spring tide for another 10 days. It will be interesting to see if it's still grounded after that.

Terry
Title: Re: The Nares Strait thread
Post by: TerryM on July 11, 2013, 08:57:02 PM
Ice island is definitely rotating in a clockwise direction by perhaps 15 degrees since yesterday.


Terry
Title: Re: The Nares Strait thread
Post by: Wipneus on July 12, 2013, 08:40:49 AM
Here is how Uni-Hamburgs  AMSR2 sea ice concentration sees it.

(red concentration going below 15%, blue going above 15%)

Title: Re: The Nares Strait thread
Post by: Espen on July 12, 2013, 10:40:44 PM
I am somehow confused how the ice is behaving in the Strait, to be honest.
Title: Re: The Nares Strait thread
Post by: no1der on July 13, 2013, 02:55:03 AM
Ice island is definitely rotating in a clockwise direction by perhaps 15 degrees since yesterday.


Terry

From overlaying the last 3 days of images, I see that the ice island is indeed rotating clockwise. The pivot point is near its southern, Greenland-facing end, where it must have fetched up on a shoal. The island is sweeping around to the east, against the flow of escaping ice (!??).
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 13, 2013, 06:32:06 AM
I overlapped the last clear MODIS image with one from a week ago.  This showed the rotation of the Petermann Ice Island, but also seemed to show that it moved SW-ward (down stream) a km or so. 

Having spent so many months stuck on a rock and fairly fixed in place by fast ice, I expect flowing water scoured the ice at the grounding site, and once free (or partially free), a new location on the ice island is connecting with the bottom.  It might rotate free or stay stuck for a while, for all I know!
Title: Re: The Nares Strait thread
Post by: Phil. on July 13, 2013, 09:39:42 PM
Here's the latest, lot's of disintegration!
http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2013194171000-2013194171500.250m.jpg (http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2013194171000-2013194171500.250m.jpg)
Title: Re: The Nares Strait thread
Post by: Espen on July 13, 2013, 10:05:20 PM
Here's the latest, lot's of disintegration!
http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2013194171000-2013194171500.250m.jpg (http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2013194171000-2013194171500.250m.jpg)

Thanks to Phil, I thought it would be quite up there today, but obviously not:
Cracks developed close to Petermann Fjord, this afternoon.
Title: Re: The Nares Strait thread
Post by: Phil. on July 14, 2013, 01:05:10 AM


Thanks to Phil, I thought it would be quite up there today, but obviously not:
Cracks developed close to Petermann Fjord, this afternoon.

Yes Espen the section south of Petermann broke up into lots of small floes today and it's still continuing, tomorrow should be interesting.

Title: Re: The Nares Strait thread
Post by: ghoti on July 14, 2013, 08:43:23 PM
The ice in the Nares has been moving in opposite directions everyday this week almost as if sloshing back and forth in a tub. Is this the usual behaviour in the Nares? Are the winds shifting that dramatically each day?
Title: Re: The Nares Strait thread
Post by: Espen on July 15, 2013, 08:43:26 AM
The break down continues:

Title: Re: The Nares Strait thread
Post by: Espen on July 15, 2013, 02:29:07 PM
Latest image:
Title: Re: The Nares Strait thread
Post by: Espen on July 16, 2013, 01:49:06 PM
Congestion ahead of Smith Sound.

Click on image to enlarge!
Title: Re: The Nares Strait thread
Post by: TerryM on July 16, 2013, 04:03:27 PM
Still no advection through Nares.


I thought Nares might be slow to open up but didn't expect it to be this late.
We're experiencing a neap tide at present and I expect Hall Basin and the rest to be open well before the spring tides of the 22nd.


It seems as though PII2012-A-1 is still too thick to make much progress through Kane Basin. IIRC it was about twice as thick as the Great Pyramid of Giza is tall when it first broke free.
The spring tide on the 22nd, while not as strong as the proxigean tide we just experienced, is still the strongest for the rest of the melt season. If our ice island doesn't find a way south it's possible it could stay in place for at least another year.
If it should withstand the summer flow through Nares it could remain an obstacle to next year's breakup, again slowing the start of advection from Lincoln Sea.


Terry



Title: Re: The Nares Strait thread
Post by: Espen on July 19, 2013, 09:02:48 AM
Very little action observed in Nares Strait, and very different to recent years:
Title: Re: The Nares Strait thread
Post by: Neven on July 19, 2013, 11:23:44 AM
Is it me or is there a lot of in situ melting?
Title: Re: The Nares Strait thread
Post by: Espen on July 19, 2013, 11:29:37 AM
For the time being it can only be in situ melting, since the ice seems to be stuck inside Nares Strait, due to currents, wind or other causes (Pll -2012?)!
Title: Re: The Nares Strait thread
Post by: TerryM on July 19, 2013, 10:42:09 PM
Espen
The images highlighting PII-2012-A-1 are really handy, shows how far south the ice has been moving.
As of today the ice in Hall Basin is holding firm. There is a strong counterclockwise gyre in Hall Basin (3 or 4 days to make a circuit as I recall) so I can't imagine any kind of ice bridge forming.
Advection from Lincoln Sea is going to start very late this year. Han island reported 10c yesterday so in situ melt should be expected.
I don't know if anyone else is intrigued by accounts of expeditions into Nares but I'm including a blog from 2009 aboard Arctic Sunrise.
http://soi.st-andrews.ac.uk/pageset.aspx?psr=495 (http://soi.st-andrews.ac.uk/pageset.aspx?psr=495)


Terry
Title: Re: The Nares Strait thread
Post by: danp on July 20, 2013, 05:57:59 AM
48 hours of motion, from processing ch. 1-4-3 of MODIS swaths.  Note the time stamps as the delay between frames is pretty irregular (it depends on the vagaries of satellite overpasses).  You can definitely see some currents or wind shoving ice back up against the southern edge of the jam, as well as the role of Peterman ice island forcing the ice around it.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FrEgi232.gif&hash=7b93f4d0a1e5a65b6278bd7ab88946b2)
Title: Re: The Nares Strait thread
Post by: Alistair on July 20, 2013, 06:54:19 PM
Thanks Danp that really shows how grounded PII-2012 is.
Title: Re: The Nares Strait thread
Post by: Espen on July 21, 2013, 03:59:43 PM
Peaking trough the clouds above Hall Basin Nares Strait, cracks now appear in front of Petermann Fjord / Hall Basin:
Title: Re: The Nares Strait thread
Post by: Espen on July 21, 2013, 05:19:28 PM
P II - 2012 is still left behind in the Nares Chaos:


    
Title: Re: The Nares Strait thread
Post by: TerryM on July 21, 2013, 06:02:32 PM
Espen
Great images!


I think when PII-2012-A-1 drifted toward the center of the channel last October (after the lights went out) it removed itself from the deepest channel and has run into a dead end trough from which it can't escape. The bathymetry isn't too clear but it seems as though there are shallower areas on three sides now. It may stay stuck there until the keel melts back or fractures.


From Arctic.io's split zoom is appears as though the dates for advection are:
2010 - July 10
2011 - July 5
2012 - July 8
2013 - July 21 and counting


The tides are increasing each cycle until spring tide on the 22nd & I think we should have advection by then. If PII2012-A-1 is still in place by the 24th it may be a permanent feature (for another year or so).


I don't know what effect the late advection will have in the Lincoln Sea or whether this is going to be an annual event as long as PII2012-A-1 remains. I'd assume that allowing MYI to build would slow melt in the eastern side of the CAA a well as the CAB. However almost all predictions I make based on something that I think I understand prove wrong [size=78%]


Terry

[/size]
Title: Re: The Nares Strait thread
Post by: Espen on July 22, 2013, 02:25:27 PM
As indicated yesterday the cracks in front of Petermann Fjord are now showing up:

Title: Re: The Nares Strait thread
Post by: Espen on July 22, 2013, 06:48:31 PM
Further action in the Strait:

1 or 2 days more we see ice moving out of Petermann Fjord.

Click on image to enlarge!
Title: Re: The Nares Strait thread
Post by: Phil. on July 23, 2013, 05:14:37 AM
More movement:
http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2013203233500-2013203234000.250m.jpg (http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2013203233500-2013203234000.250m.jpg)
Title: Re: The Nares Strait thread
Post by: Phil. on July 23, 2013, 04:19:46 PM
Further action in the Strait:

1 or 2 days more we see ice moving out of Petermann Fjord.

Click on image to enlarge!

Today's Aqua image shows more action in the Hall basin.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi302.photobucket.com%2Falbums%2Fnn107%2FSprintstar400%2FNares.jpg&hash=97962773aff4fbe1f34b9fe3b1b4e417)
Title: Re: The Nares Strait thread
Post by: Espen on July 23, 2013, 06:56:02 PM
P2-2012 is still left behind in the chaos of Nares:

Please click on image to enlarge!
Title: Re: The Nares Strait thread
Post by: Jmo on July 25, 2013, 08:46:10 AM
Espen and other aficionados.   8)
You've been looking at these things for far longer than I. It amazes how quickly things are changing in Nares. Obviously it just takes the right conditions to develop over some time and then off it goes? Truly looks like solid breakup, but also significant in situ melt?  Just noticing how the ice is rapidly becoming bluer (or an artifact of the satellite image?) and also the edges "smooth" off.  Nares Express really close to fully opening now.
Title: Re: The Nares Strait thread
Post by: Espen on July 25, 2013, 08:53:43 AM
JMO;

Yes in the CAA (Canadian Arctic Archipelago) and Nares in situ melting is often seen, and it is in my opinion a "small" test bed for the rest of the Arctic Ocean, I always argued the over nite scenario where the sea ice "evaporates" very quickly.   
Title: Re: The Nares Strait thread
Post by: Phil. on July 26, 2013, 04:22:36 PM
Although it's cloudy the latest MODIS is showing significant melting opposite the mouth of the Petermann glacier (particularly Archer fjord).  Location near the center of the image.

http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2013207103000-2013207103500.250m.jpg (http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2013207103000-2013207103500.250m.jpg)
Title: Re: The Nares Strait thread
Post by: Espen on July 26, 2013, 04:38:22 PM
Phil;

Yes I have noticed it is about half empty of ice, and looks as Hall Basin is pretty empty too, wonder what is going in the P-fjord. Bad we don't have the radar images anymore! :(
Title: Re: The Nares Strait thread
Post by: Espen on July 26, 2013, 07:04:49 PM
Nares Strait is beginning to pull sea ice in from Lincoln Sea:

Heavy clouds over Nares Strait.
Title: Re: The Nares Strait thread
Post by: ghoti on July 26, 2013, 11:11:56 PM
Where is buoy 2013C relative to that open water at the Nares / Lincoln interface?
Title: Re: The Nares Strait thread
Post by: Espen on July 26, 2013, 11:26:11 PM
Its about 25 km form Cape Belknap (just north of Alert ,Ellesmere Island) or about 70 km from the entrance of Nares Strait (centerline).
Title: Re: The Nares Strait thread
Post by: Espen on July 29, 2013, 07:58:36 PM
Nares Strait and in particular Kane Basin is crowded this season and I believe the culprit is PII-2012.

Click on image to enlarge and better details!
Title: Re: The Nares Strait thread
Post by: TerryM on July 30, 2013, 02:36:16 AM
Espen
I'm not yet willing to claim that Nares Strait is open to advection even though Hall Basin is clear. The latest date I've found was in 2009 at July 14th. PII20112-A-1 has made a huge difference in the timing of the start of advection and as you point out may now be impeding the flow.
My guess is that it will survive this melt season, and possibly the next few seasons as well.


Terry
Title: Re: The Nares Strait thread
Post by: Phil. on July 31, 2013, 12:36:09 AM
The stalled ice island definitely appears to impede progress but my impression is that the wind/current is headed north at present.  See for example the open water to the N of the island and the lack of progress of the ice pieces to the South which wouldn't be obstructed by the ice island.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 31, 2013, 02:25:57 PM
I agree, Phil.   I've read that water routinely flows both 'north' and 'south' in Nares Strait, and I have observed icebergs moving around (counterclockwise) in a gyre within Kane Basin in previous years. (I've not studied this this year.)  Obviously, any island (rock or ice) will impede movement, but I do not think PII-2012 is particularly keeping ice from Smith Strait.  (I do expect PII-2012 delayed Nares Strait from opening, however.)
Title: Re: The Nares Strait thread
Post by: Phil. on July 31, 2013, 03:01:13 PM
Today's MODIS image posted by Espen shows a slight northern flow and in situ melting compared with earlier images.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fforum.arctic-sea-ice.net%2Findex.php%3Faction%3Ddlattach%3Btopic%3D53.0%3Battach%3D3144%3Bimage&hash=275218556a02c38c9baf07ee7a068300)
Title: Re: The Nares Strait thread
Post by: Phil. on August 04, 2013, 08:14:20 PM
Today's MODIS image posted by Espen shows a slight northern flow and in situ melting compared with earlier images.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fforum.arctic-sea-ice.net%2Findex.php%3Faction%3Ddlattach%3Btopic%3D53.0%3Battach%3D3144%3Bimage&hash=275218556a02c38c9baf07ee7a068300)

The latest Modis view of the Nares seems to be starting to clear again, looks like the southerly flow has restarted.
http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2013216134000-2013216134500.2km.jpg (http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2013216134000-2013216134500.2km.jpg)
Title: Re: The Nares Strait thread
Post by: Phil. on August 08, 2013, 10:32:40 PM
A good clear look at the Nares today on MODIS shows further clearing and floes entering from the North.
Petermann fjord also showing melting out of the seaice back towards the glacier.

http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2013220131500-2013220132000.2km.jpg (http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2013220131500-2013220132000.2km.jpg)
Title: Re: The Nares Strait thread
Post by: Espen on August 11, 2013, 08:37:56 PM
PII-2012 is still not moving:

Please click on the image to enlarge.
Title: Re: The Nares Strait thread
Post by: Wipneus on August 14, 2013, 09:56:09 AM
PII-2012 has moved south, visible on the AMSR2 ice concentration map, and NASA Wordlview:
https://forum.arctic-sea-ice.net/index.php/topic,382.msg12416.html#msg12416 (https://forum.arctic-sea-ice.net/index.php/topic,382.msg12416.html#msg12416)
Title: Re: The Nares Strait thread
Post by: Yuha on August 14, 2013, 12:25:02 PM
PII-2012 has moved south, visible on the AMSR2 ice concentration map, and NASA Wordlview:
https://forum.arctic-sea-ice.net/index.php/topic,382.msg12416.html#msg12416 (https://forum.arctic-sea-ice.net/index.php/topic,382.msg12416.html#msg12416)

It's actually moved north from where it was stuck.

It kept pivoting around one corner (see first two images attached) and
that corner is still stuck at the same place but the rest of it is now loose.
Title: Re: The Nares Strait thread
Post by: Jim Hunt on August 14, 2013, 12:50:03 PM
That corner is still stuck at the same place but the rest of it is now loose.

Check an image from the 13th (http://earthdata.nasa.gov/labs/worldview/index.html?map=-702621.190435,-1143884.349154,-341149.190435,-902220.349154&products=baselayers,MODIS_Aqua_CorrectedReflectance_TrueColor~overlays,arctic_graticule_3413,arctic_coastlines_3413&time=2013-08-13&switch=arctic) Yuha. The whole thing is now loose, and had moved south several km by then.
Title: Re: The Nares Strait thread
Post by: Espen on August 14, 2013, 01:04:57 PM
I would call it a sideway movement:

Title: Re: The Nares Strait thread
Post by: Wipneus on August 14, 2013, 01:17:49 PM
Animation: movement from 12->13 August is by far the largest of the whole period and is south. Cannot see the little piece of resistance that refuses to move.
Title: Re: The Nares Strait thread
Post by: Jim Hunt on August 14, 2013, 02:42:24 PM
Cannot see the little piece of resistance that refuses to move.

Me neither. Perhaps we can agree its centre of gravity ambled slowly northward before racing south again yesterday?

P.S. Actually I think I can see what Yuha was getting at now. On the 8th you can see "one corner" has split off from the rest of PII-2012. Although invisible through the clouds on the 13th, you can see on the 11th and 12th that the small corner gets left behind whilst the main bulk of PII-2012 sails off first north, then south.
Title: Re: The Nares Strait thread
Post by: danp on August 14, 2013, 05:18:32 PM
It's actually moved quite a lot over the past week or so after being stuck for so long.  Here's an animation from day 216-224, with all clear-ish swaths picked out.  500m resolution, MODIS Terra:

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2F2fsvAZS.gif&hash=b0ca3cc00f122c0efcc1ef3523335389)

And here's a sub-animation with 7 clear frames showing distinct positions of the island:

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FaQuZfvb.gif&hash=ea9fa9f961b658c8e1035474168311c4)
Title: Re: The Nares Strait thread
Post by: Espen on August 14, 2013, 05:31:46 PM
There seems to be a threshold somewhere at the bottom of the Strait which make the escape of PII-2012 difficult.
Title: Re: The Nares Strait thread
Post by: TerryM on August 14, 2013, 07:31:51 PM
I think this will make a difference in next year's melt pattern.
I had expected PII2012-A-1 to remain in place since it missed an opportunity to sail off with the extreme spring tide in June. When it missed the next spring tide I assumed my hunch had been correct. Oh well[size=78%]
The flat side of the ice island was the side that made up the calving front of Petermann the right of that was the portion that should have had the deepest keel (because of the direction of warm water entering the fjord). As it entered Kane Basin the deep keel ran aground and it was pivoting about that point as late as October 2012 after the sun had already set.
The full moon was on Aug. 6 with high spring tide at Cape Lawrence on the 10th. Winds from the south were building and maxed at Littleton Island at 32.2 m/s (116 Kph or 72 miles/hr.) on the 10th. The island may have begun it's northern movement prior to this.
I think that PII2012-A-1 had been stuck in some sort of dead end ravine and the wind, tide and surge floated the island and drove it north out of the low spot it had been trapped in. Kane's bathymetry shows deeper waters to the west of where the island had wintered and the ice island seems to have slipped through in that area.


Whatever fragments of PII2012-A-1 remain in 2014 will probably join their brothers grounded mainly off Baffin Island. They shouldn't present any problems to the melting of the Nares Ice Bridge in 2014 & I'd expect advection to begin in the first week of July as has been the case in most recent years. Understanding how much effect the blockage of Nares has had on this year's melt is way above my pay grade, but I wonder if this contributed to the dearth of advection through Fram Strait.


Terry[/size]
Title: Re: The Nares Strait thread
Post by: Espen on August 14, 2013, 07:50:49 PM
It has been colder in the area this season, the 2 lakes (Romer Lakes) at the end of the Petermann Glacier,on the edge of GIS, did not really become ice free this season, as is normal in August, and the first snow is already seen all around the Petermann Area. This colder weather this year was another factor slowing the melt in Nares and several other places:

 
Title: Re: The Nares Strait thread
Post by: Jim Hunt on August 14, 2013, 09:39:11 PM
The image is a bit hazy, but the ice island is still travelling south at a rate of knots:

 
Title: Re: The Nares Strait thread
Post by: Espen on August 14, 2013, 10:25:06 PM
Jim,

Yes PII-2012 traveled south about 2 times its own length since August 13 2013 (yesterday).
Title: Re: The Nares Strait thread
Post by: Espen on August 14, 2013, 10:38:52 PM
Here is an animation:
Title: Re: The Nares Strait thread
Post by: icebgone on August 15, 2013, 02:42:33 AM
Terry, I think, like you, that the plug in Nares has helped save MYI.  It was aided and abetted by the cold weather and the earlier loss of oceanic and atmospheric heat during the SSW events.  The balance between oceanic influence and atmospheric wave configuration that results in + and - dipole constructs needs lots of research.  Unfortunately, we are probably going to see a reduction in satellite based climate capabilities over the next 4-5 years as old satellites cease operation and are not replaced due to cost constraints.
Title: Re: The Nares Strait thread
Post by: TerryM on August 15, 2013, 03:41:53 AM
ibg
I think you're right on so many counts.I hadn't meant to imply that the Nares Strait situation was the sole player, or even necessarily one of the large players in the muted melt we've seen. I do think that it has been part of the mix however. The colder temperatures Espen mentioned in Greenland and Ellesmere alone could have prolonged the ice bridge, but the ice island was the big player in that region.
I hope you are wrong about the satellite situation. If we're being driven off a cliff I'd prefer not to be wearing blinders.
Terry
Title: Re: The Nares Strait thread
Post by: Patrick on August 16, 2013, 01:02:10 PM
Yesterday, browsing through the images at EOSDIS Worldview, I noticed that PII-2012 seemed to be on a collision course with a small island off the coast of Ellesmere Island. The latest swath image indicates that PII-2012 got turned by the current, but I'm still wondering if it will be enough to fully avoid Pim Island.

Image Source: http://lance-modis.eosdis.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2013228002500-2013228003000.250m.jpg (http://lance-modis.eosdis.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2013228002500-2013228003000.250m.jpg)
Title: Re: The Nares Strait thread
Post by: Espen on August 16, 2013, 01:38:40 PM
Looks like PII-2012 passed that hurdle:
Title: Re: The Nares Strait thread
Post by: Patrick on August 16, 2013, 02:14:35 PM
Yes, here's an even better image...

Image Source: http://lance-modis.eosdis.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2013228091000-2013228091500.250m.jpg (http://lance-modis.eosdis.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2013228091000-2013228091500.250m.jpg)
Title: Re: The Nares Strait thread
Post by: Phil. on August 18, 2013, 01:45:43 PM
Well past Pim Island now, on the other side of the strait.

http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2013229162500-2013229163000.250m.jpg (http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2013229162500-2013229163000.250m.jpg)
Title: Re: The Nares Strait thread
Post by: Espen on August 19, 2013, 01:41:01 PM
Someone pulled the plug!

The sea ice from Lincoln Sea is now filling up Nares Strait:
Title: Re: The Nares Strait thread
Post by: Jim Hunt on August 19, 2013, 01:55:18 PM
The sea ice from Lincoln Sea is now filling up Nares Strait:

As evidenced by the continuing motion of IMB 2013C (http://batchgeo.com/map/imb-2013c), though it has slowed up over the last 24 hours or so:
Title: Re: The Nares Strait thread
Post by: Espen on August 19, 2013, 01:59:31 PM
Yes and it may end up in Lady Franklin Bay and Archer Fjord, or in a Cul-de-sac!
Title: Re: The Nares Strait thread
Post by: Andreas Muenchow on August 20, 2013, 11:01:17 PM
It'll be past Hans Island and Kane Basin, but I have been wrong before ;-)

Thank you for posting this.
Title: Re: The Nares Strait thread
Post by: Espen on August 22, 2013, 02:50:36 PM
Do we know where PII-2012 is now?
Title: Re: The Nares Strait thread
Post by: Wipneus on August 22, 2013, 03:51:32 PM
I was wondering the same thing. On my AMSR2 maps, it disappears near the Greenland coast:

Title: Re: The Nares Strait thread
Post by: Espen on August 22, 2013, 03:55:44 PM
I believe it already passed Smith Sound, I may be wrong, it was at the mouth of the sound a week ago?
Title: Re: The Nares Strait thread
Post by: Yuha on August 22, 2013, 04:15:59 PM
I believe it already passed Smith Sound, I may be wrong, it was at the mouth of the sound a week ago?

It was still in Smith Sound on the 19th. Just visible through clouds in the Aqua image:

http://earthdata.nasa.gov/labs/worldview/?map=-793996.065578,-1228434.188424,-384396.065578,-997010.188424&products=baselayers,MODIS_Aqua_CorrectedReflectance_TrueColor~overlays,arctic_coastlines_3413&time=2013-08-19&switch=arctic (http://earthdata.nasa.gov/labs/worldview/?map=-793996.065578,-1228434.188424,-384396.065578,-997010.188424&products=baselayers,MODIS_Aqua_CorrectedReflectance_TrueColor~overlays,arctic_coastlines_3413&time=2013-08-19&switch=arctic)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on August 22, 2013, 05:16:44 PM
PII-2012 is clearly visible at the top of DMI’s Qaanaaq TERRA August 17, 2013 image (snapshot attached).  I don't see it afterwards through the clouds.  (I don't have access to Worldview, alas, so don't know where it went two days later.)  DMI:  http://ocean.dmi.dk/arctic/kane.uk.php (http://ocean.dmi.dk/arctic/kane.uk.php).  (To select only TERRA images, click "TERRA" then "Hent" button in the lower right section of webpage.)
Title: Re: The Nares Strait thread
Post by: Espen on August 22, 2013, 07:35:32 PM
PII-2012 showed up again today, but it is not obvious where it is exactly, but somewhere in the Smith Sound / Kane Basin area.
Title: Re: The Nares Strait thread
Post by: TerryM on August 22, 2013, 08:12:54 PM
It appears as having moved just over one length due north from it's position on the 17th. I believe it's still in very deep water with little chance of grounding unless the northern (eastside) current takes it back into the Kane Basin Gyre.
Since I think this is extremely unlikely & since this is still the melt season of 2013 it will probably happen.
Terry
Title: Re: The Nares Strait thread
Post by: TerryM on August 22, 2013, 08:34:51 PM
Below is the Bathymetry in the region
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Ficyseas.files.wordpress.com%2F2012%2F09%2Fnaresstraitbath2012.png%3Fw%3D500&hash=a00232818ddbc0a3d80c76d41a2409a2)


Thanks to Andreas's site from 2012.


Another image that may help is this from PII2010-B as it passed over Andreas's sensors in Nares Strait.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Ficyseas.files.wordpress.com%2F2012%2F08%2Fkf02-sept22-backscatter-e1346557695479.png%3Fw%3D500&hash=67785b66551af166bfb9b042464c727f)


Bear in mind that the thin, forward end of PII2012-A-1 would have been mated to the thick trailing end of PII2010-B shown above and the deepest keel probably at or near the north west corner when it was part of the glacier because of the coriolis effect within the Fjord.
The coriolis effect is also what forces the northward stream in Nares Strait to the eastern (Greenland) side.
Terry
Title: Re: The Nares Strait thread
Post by: Phil. on August 23, 2013, 05:24:32 AM
PII-2012 showed up again today, but it is not obvious where it is exactly, but somewhere in the Smith Sound / Kane Basin area.

Clear shot of it in Smith Sound today:
http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2013234211500-2013234212000.250m.jpg (http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2013234211500-2013234212000.250m.jpg)
Title: Re: The Nares Strait thread
Post by: Espen on August 23, 2013, 08:53:41 AM
It is strange bird this PII-2012, it is like a condor chick who dont want to leave the nest.
Title: Re: The Nares Strait thread
Post by: Espen on August 23, 2013, 09:27:06 AM
Here is she is:
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on August 23, 2013, 09:04:29 PM
PII-2012 appears to be a calf searching for her mother. Baffin Bay must have frightened her, it being so awfully big.   :P
Title: Re: The Nares Strait thread
Post by: Phil. on August 24, 2013, 03:15:54 AM
Here is she is:

Looking at today's MODIS she appears to be drifting slightly north at present.
Title: Re: The Nares Strait thread
Post by: Espen on August 27, 2013, 07:15:52 PM
P2 is still in a irresolute mood:
Title: Re: The Nares Strait thread
Post by: Phil. on August 27, 2013, 11:39:55 PM
Moving south again after wandering around in an eddy for a few days.
Title: Re: The Nares Strait thread
Post by: Wipneus on August 29, 2013, 08:38:14 AM
PII-2012 is making good speed, and is now further than ever before.

Title: Re: The Nares Strait thread
Post by: Espen on August 29, 2013, 06:03:52 PM
PII-2012 still hanging around in Smith Sound:
Title: Re: The Nares Strait thread
Post by: TerryM on August 29, 2013, 07:28:15 PM
PII-2012-A-1 should be in deep waters if it can stay away from the narrow shoal water very close to Ellesmere Island. As it's presently positioned the thickest keel is the side closest to Ellesmere. The bottom drops away quite rapidly on the western shore in this area but it's not impossible that the very deep keel could snag on an unmapped protrusion.
I'd hate to find our boy aiding in maintaining another ice bridge after it threaded itself through Kane Basin this summer.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fwww.issibern.ch%2Fteams%2FPolynya%2Fimage003.gif&hash=cea70b32e6f57aaba1ddce37c6500196)


It's journey south will be fun to trace next year. I hope someone either repairs or replaces the tracking device on it as I think it will be the biggest thing to pass through Baffin Bay in a very long time. The remnants of PII-2010 attracted lots of attention when it finally grounded off Newfoundland & this one is much larger by volume and appears to be staying more or less intact.
If it should end up threatening the Hibernia Oil Platform things could get very interesting.


Dr.Munchow has an interesting article that traced PII-2012- A & PII-2010-B's journey's in 2011 at:
http://icyseas.org/2012/01/06/petermann-ice-island-2010-through-2011-part/ (http://icyseas.org/2012/01/06/petermann-ice-island-2010-through-2011-part/)
from which I pilfered the following graphic showing the track of PII-2010-A and a much smaller ice island from 2008.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Ficyseas.files.wordpress.com%2F2012%2F01%2Fpath-ai.png%3Fw%3D500&hash=4f9be17d12a7291562c0f6e62a4e5e4e)
Title: Re: The Nares Strait thread
Post by: Espen on August 30, 2013, 02:42:12 PM
PII-2012 is on a test flight into Baffin Bay, whether it return to Kane remains to be seen. It is now positioned between Baird Inlet and Cadogan Inlet of Gale Point ,Ellesmere Island.
Title: Re: The Nares Strait thread
Post by: Laurent on August 30, 2013, 02:53:12 PM
It seems there is 2 opposite flow, one going north and one south !? nearly as equal in strengh ?
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on August 30, 2013, 04:25:15 PM
http://www.ingentaconnect.com/content/jmr/jmr/2008/00000066/00000006/art00005 (http://www.ingentaconnect.com/content/jmr/jmr/2008/00000066/00000006/art00005) indicates a strong (95%) southerly current in Nares Strait and a minor (5%) northerly current on the Greenland side.   In previous years, I "watched" floes stuck in an anticlockwize gyre in Kane Basin.
Title: Re: The Nares Strait thread
Post by: Espen on August 30, 2013, 07:11:04 PM
PII-2012 still moving south:
Title: Re: The Nares Strait thread
Post by: Espen on August 30, 2013, 11:00:15 PM
Terry, take good care of her she is in Canadian water now! ;)
Title: Re: The Nares Strait thread
Post by: TerryM on August 31, 2013, 07:55:47 AM
Espen
Next stop the Hibernia Oil Platform (by next year?)
Terry
Title: Re: The Nares Strait thread
Post by: Phil. on August 31, 2013, 03:00:04 PM
Drifting closer to the Ellesmere Island coast.
http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2013242185000-2013242185500.250m.jpg (http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2013242185000-2013242185500.250m.jpg)
Title: Re: The Nares Strait thread
Post by: TerryM on September 05, 2013, 04:02:59 AM
There is a French sailing yacht "Vagabond" in Kane Basin that probably was in visual contact with PII-2012-A-1 a few days ago. It's callsign is FLAO and is being tracked by Sailwx and Meteo France at
http://www.sailwx.info/shiptrack/shipposition.phtml?call=FLAO (http://www.sailwx.info/shiptrack/shipposition.phtml?call=FLAO)
and
http://www.meteo2.shom.fr/cgi-bin/meteo/display_vos_ext.cgi?callchx=FLAO (http://www.meteo2.shom.fr/cgi-bin/meteo/display_vos_ext.cgi?callchx=FLAO)


Someone able to understand French might be able to glean some interesting data if they could somehow make contact with the ship or find reports that they've been transmitting. I found it interesting that they report temperatures as high as 3.5C on the 3d, but if they have photos or first hand accounts of the ice island these might be of great interest to our community.
I apologize for not taking this any further but I know my limits.
Terry


Edit - Updated - Their Log Book is at
http://www.vagabond.fr/news.en (http://www.vagabond.fr/news.en)
but hasn't been updated since 8/25. This probably should be on a different thread.
Title: Re: The Nares Strait thread
Post by: Wipneus on September 05, 2013, 08:29:43 AM
It looks like it is in relatively open water now.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on September 06, 2013, 02:16:36 PM
Ice island is clearly in Baffin Bay.  Image is from today's DMI Qaanaaq section NOAA imagry

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FQaanaaq%2F201309060133.NOAA.jpg&hash=775dcd0dc8157066a441d2555b4ea63c)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on September 06, 2013, 04:56:08 PM
Although now "clearly" in Baffin Bay, the ice island has been in Baffin Bay since it entered Hall Basin, according to http://en.wikipedia.org/wiki/File:Baffin_Bay,_Canada.svg (http://en.wikipedia.org/wiki/File:Baffin_Bay,_Canada.svg).  The International Hydrographic Organization (per Wikipedia) defines the northern limits of Baffin Bay as a line from Cape Sheridan (E of Alert, Ellesmere Is.) to Cape Bryant, Greenland (approx. due E of Alert), and includes all of Nares Strait, etc.  (The first Wikipedia map of Baffin Bay shows grossly inaccurate northern and southern boundaries - actual official boundaries being significantly north of the indicated boundaries).
Title: Re: The Nares Strait thread
Post by: Espen on September 06, 2013, 05:38:20 PM
And here is the Chick far from the nest in Greenland:
Title: Re: The Nares Strait thread
Post by: Phil. on September 11, 2013, 09:40:27 PM
And here is the Chick far from the nest in Greenland:

Looks like she's broken in two now!

http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2013254173500-2013254174000.250m.jpg (http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2013254173500-2013254174000.250m.jpg)
Title: Re: The Nares Strait thread
Post by: TerryM on September 11, 2013, 11:43:58 PM
Very good catch Phil!


The "Vagabond" crew actually has walked on the island. Their account of the adventure is at
http://www.vagabond.fr/news.en/20130829-0000 (http://www.vagabond.fr/news.en/20130829-0000)
and Andreas has more information at
http://icyseas.org/2013/09/09/petermann-ice-island-visited-by-vagabond/#comment-3014 (http://icyseas.org/2013/09/09/petermann-ice-island-visited-by-vagabond/#comment-3014)


I'm guessing it snagged on an unmapped sea mound and at the speed she was going broke into the 3 fragments I'm counting. Does this leave us with PII-2012-A-1, PII-2012-B-1. PII-2012-C-1 or PII-2012-A-1, PII-2012-A-2 and PII-2012-A-3? I think it's the latter set since IIRC a PII-2012-B had split off last year in Nares Strait.


Instead of having to dodge one bullet it seems as though the Hibernia Platform may have to evade a fusilade.
Terry
Title: Re: The Nares Strait thread
Post by: Espen on September 12, 2013, 08:45:55 AM
As reported earlier by Phil.

The separation happened between Carey Islands (Greenland) and Clarence Head (Ellesmere Island)

Here is a closer look, PII-2012 is divided into 2 large pieces and another 2 much smaller pieces:

Please click on image to enlarge!

Title: Re: The Nares Strait thread
Post by: Andreas Muenchow on September 13, 2013, 02:48:42 AM
The 200 meter thick ice island did plow into the bottom and broke apart cleanly along a central channel where the ice is only half as thick as it is towards the sides of these channels. More details, imagery, references, links, and photos at IcySeas.
Title: Re: The Nares Strait thread
Post by: Wipneus on September 13, 2013, 08:20:59 AM
It (they) did not move much for a day.
Title: Re: The Nares Strait thread
Post by: Andreas T on September 17, 2013, 12:48:35 AM
Another nice shot on http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2013259175500-2013259180000.250m.jpg (http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2013259175500-2013259180000.250m.jpg)
Is it about to hit by sea ice? Will that get it more stuck or increase drag on it from the current out of Nares strait?
Title: Re: The Nares Strait thread
Post by: TerryM on September 17, 2013, 08:05:13 AM
I believe the segment labeled as PII-2012-A-e-1 is still grounded with the other sections traveling with the current. Split zooms using Sept.11 & Sept 14 appear to confirm this.
The below is from Dr. Muenchow's site and shows the naming of the various remaining islands.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Ficyseas.files.wordpress.com%2F2013%2F09%2Fpii-2012-a-1-after-split-on-11-sep-2013.jpg%3Fw%3D370%26amp%3Bh%3D&hash=17183b0aefae395104b7c9a1eac69441)
Terry
Title: Re: The Nares Strait thread
Post by: Andreas T on September 18, 2013, 10:37:14 PM
http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2013261174000-2013261174500.250m.jpg (http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2013261174000-2013261174500.250m.jpg)
today shows both large pieces still in this position as far as I can tell.
I'll try to attach a cropped image, first attempt at this
Title: Re: The Nares Strait thread
Post by: Jim Hunt on September 19, 2013, 12:33:23 AM
After hanging around opposite Petermann for ages, Ice Mass Balance Buoy 2013C has got a move on recently, and is now heading out into Baffin Bay. For a close inspection see http://batchgeo.com/map/imb-2013c (http://batchgeo.com/map/imb-2013c)

On its best day it travelled 86.5 km
Title: Re: The Nares Strait thread
Post by: TerryM on September 22, 2013, 07:28:21 PM
Everything with the exception of PII-2012-A-1-f appears to be afloat again and heading south after the spring tide of the 20th. At some point they will all be caught up in the freeze and will spend the winter either grounded or frozen into the sea ice in deep waters. The polar bears witnessed by the Vagabond's crew are in for a long voyage.
Terry
Title: Re: The Nares Strait thread
Post by: Andreas T on September 23, 2013, 10:17:50 PM
A teasing glimpse of PII-2012-A-1-f  in today's modis http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2013266180000-2013266180500.250m.jpg (http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2013266180000-2013266180500.250m.jpg)

Title: Re: The Nares Strait thread
Post by: Andreas T on September 30, 2013, 12:21:20 AM
With clear sky today terra confirms Terry's description. PII-2012-A-1-f stuck in place since the 20th, PII-2012-A-1-e seems stranded a little further south. Sea ice drifting past both.
http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2013272190000-2013272190500.250m.jpg (http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2013272190000-2013272190500.250m.jpg)
Title: Re: The Nares Strait thread
Post by: Andreas T on September 30, 2013, 12:38:12 AM
It only occurred to me after posting to look up place names posted by Espen https://mapsengine.google.com/map/viewer?mid=zbdKKg4fRHYo.kugA5VIgp5ec (https://mapsengine.google.com/map/viewer?mid=zbdKKg4fRHYo.kugA5VIgp5ec)
PII-2012-A-1-f off Clarence Head, PII-2012-A-1-e northeast of Coburg Island
Title: Re: The Nares Strait thread
Post by: Andreas T on October 07, 2013, 01:18:05 AM
another glimpse of PII-2012-A-1-f and PII-2012-A-1-e. As ice around them becomes more coherent and lighter in colour (thicker/ snow covered?) they are becoming more difficult to spot, but the shapes show up against open water on their southern side
http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2013279173000-2013279173500.250m.jpg (http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2013279173000-2013279173500.250m.jpg) drawing a line from Cape Norton Shaw to the Carey Islands helps
I just find it fascinating to watch this remote place as autumn progresses
Title: Re: The Nares Strait thread
Post by: Wipneus on January 30, 2014, 10:10:47 AM
Landsat 8 hires (15m)  image of PII-2012 on Sep 6. Just left the Smith Sound and a few days before the break.

Open cracks are visible at top and bottom. Smaller icebergs have already left the ship (more can be seen on the full 600MB image)

The "central channel" along it will break is ready for separation.

Click on the image for the full resolution!
Title: Re: The Nares Strait thread
Post by: Espen on January 31, 2014, 10:05:33 PM
Wipneus,

The "Central Channel" (previous melt river) is not necessary where it will break, it may do so, but it is only a "small" cut relative to the thickness of that "island".

But it is a like scratch in a window?
Title: Re: The Nares Strait thread
Post by: Wipneus on February 01, 2014, 08:47:29 AM
Espen, I guess you are right. The break might not be right at that visible channel, but near and parallel to it. I could not locate a landsat image after the break, I will look again.
Title: Re: The Nares Strait thread
Post by: Wipneus on February 01, 2014, 10:10:40 AM
Found it, break was indeed at the darker band south of the central stream channel.

Large varying shadows show thickness of the iceberg shards are quite different.

(Click on attached image for the full resolution)
Title: Re: The Nares Strait thread
Post by: Espen on February 01, 2014, 12:18:09 PM
Wineus,

Where is the Island actually located now?
Title: Re: The Nares Strait thread
Post by: Wipneus on February 01, 2014, 01:26:00 PM
According the LandsatLook viewer at 76.69oN and -76.02oW. About 40km from DevonEllesmere Island.

It is visible on the last available landsat image on the 10th of Oktober.
Title: Re: The Nares Strait thread
Post by: Espen on February 01, 2014, 02:13:22 PM
Thanks Wipneus,

Looking forward to your magic with the landsat images :D
Title: Re: The Nares Strait thread
Post by: Wipneus on February 01, 2014, 04:43:33 PM
Sorry that was Ellesmere. I located the other big shard 85km SW of the other piece.
In the attached image the island is Coburg, in the middle of the exit from the Jones Sound.

Click on the image for the full res image, icebergs can be distinguished from sea ice by the shadows that their height is casting.
Title: Re: The Nares Strait thread
Post by: Espen on February 01, 2014, 04:50:14 PM
Wipneus;

Are you sure about Ellesmere Island, I think it is Coburg Island?
Title: Re: The Nares Strait thread
Post by: Wipneus on February 02, 2014, 09:19:08 AM
The first shard I showed is nearer Ellesmere, the second near Coburg Island.

Here, a low res but full image with several icebergs marked on the 10th of October.

[edit: added a scaled bar for reference]
Title: Re: The Nares Strait thread
Post by: Espen on February 02, 2014, 11:34:29 AM
Wpneus,

Thanks now I understand ;)
Title: Re: The Nares Strait thread
Post by: Polynya88 on February 03, 2014, 02:55:24 PM
The first shard I showed is nearer Ellesmere, the second near Coburg Island.

Here, a low res but full image with several icebergs marked on the 10th of October.

Interesting to note in the attached Ice chart (where these two ice islands are tracked) how the upper one is obviously grounded, and the lower one has drifted 495KM!>
Title: Re: The Nares Strait thread
Post by: Wipneus on February 04, 2014, 08:04:48 AM
The first shard I showed is nearer Ellesmere, the second near Coburg Island.

Here, a low res but full image with several icebergs marked on the 10th of October.

Interesting to note in the attached Ice chart (where these two ice islands are tracked) how the upper one is obviously grounded, and the lower one has drifted 495KM!>

LandsatLook viewer gives me ~85 km, counting pixels (of 16*15=240m) gives me about the same distance. I have added a scaled bar to the image to make the distances clearer.

Title: Re: The Nares Strait thread
Post by: Andreas Muenchow on February 05, 2014, 08:51:25 PM
I very much like the LandSat-8 imagery, thank you for sharing, Wipneus.

Detailed profiles of both the surface and bottom (and melt rates) of Petermann's ice shelf from laser and ice-sounding radar are shown in the attached plots. The vertical bars on the first one (Fig.-3) show the limits of the 2010 and 2012 ice islands while they were still attached. The paper will appear later this year in the Journal of Glaciology. Pre-prints available at my web-site or blog. Data are in the public domain via NSIDC which is where I found them.
Title: Re: The Nares Strait thread
Post by: Sonia on March 02, 2014, 07:02:06 PM
Amazing ASAR image of the Kane Basin today.
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20140302rs02.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20140302rs02.ASAR.jpg)
If we can interpret the lighter shades as thicker ice, it's clear there is no continuity in any arch-like line.  Two pieces of the fast ice broke off last week.  It's fascinating to git a better look at the sites where they broke and speculate about how the remaining ice might hold up in the coming melt season.
Title: Re: The Nares Strait thread
Post by: Espen on March 02, 2014, 07:35:16 PM
Hi Sonia, I see you got in the DMI Image Box too! ;)
Title: Re: The Nares Strait thread
Post by: Jim Hunt on March 02, 2014, 08:52:44 PM
Amazing ASAR image of the Kane Basin today.

I now see lots of amazing images suddenly available via DMI. However last I heard ENVISAT was dead:

http://www.esa.int/Our_Activities/Observing_the_Earth/Envisat/ESA_declares_end_of_mission_for_Envisat (http://www.esa.int/Our_Activities/Observing_the_Earth/Envisat/ESA_declares_end_of_mission_for_Envisat)

Has it been magically resurrected?
Title: Re: The Nares Strait thread
Post by: Andreas T on March 02, 2014, 10:24:06 PM
....
If we can interpret the lighter shades as thicker ice, it's clear there is no continuity in any arch-like line.  Two pieces of the fast ice broke off last week.  It's fascinating to get a better look at the sites where they broke and speculate about how the remaining ice might hold up in the coming melt season.
interpreting the ASAR images is not so straightforward, it seems. Some of the lighter shades are definitely floes of older ice which has come down from the Lincoln Sea. Other parts seem to show roughness of compacted or fractured ice. Some dark areas show ice which has been in place longer than some of the lighter shades but undisturbed / fractured. An interesting comparison can be seen at Peterman glacier (linked to by Espen earlier)
 http://ocean.dmi.dk/arctic/image_container.php (http://ocean.dmi.dk/arctic/image_container.php)where the much thicker glacier ice shows up darker than sea ice in the fjord in front of it.
Great to have these radar images nevertheless, does anybody know why they have reappeared?
Title: Re: The Nares Strait thread
Post by: Polynya88 on March 02, 2014, 11:38:46 PM
Interpreting radar imagery can be tricky, as dark tones can mean smooth ice (200cm), or very New ice (5cm), or Grease ice (2cm). Bright tones can be rough young ice (5-15cm), or rough First-year ice (>150cm), or Multi-year rubble (>3m), or icebergs. The big trick to interpreting radar imagery correctly is to look at the fracture type of the target. Thin/New ice has ragged fractures, Thin FY has more angular fractures, and Multi-year ice can have very long straight fractures. Decayed second-year ice has curvilinear fractures, etc. etc. The study and use of fracture type and shape is the only reliable way to interpret radar imagery; tone can be dark one day, then bright the next day, then in-between the next day, all depending on wind/weather. Using tone alone to interpret radar imagery is a rookie mistake. ;)
Title: Re: The Nares Strait thread
Post by: Wipneus on March 14, 2014, 09:59:25 AM
Landsat 8 image of the Kane Basin with ice arch.

The low sun (elevation 7.6 degrees) makes it as yet difficult to say much more about the state of the stuck sea ice.
Title: Re: The Nares Strait thread
Post by: Jim Hunt on March 23, 2014, 03:06:48 PM
I now see lots of amazing images suddenly available via DMI. However last I heard ENVISAT was dead. Has it been magically resurrected?

In answer to my own question, the DMI "ASAR" images now say "RADARSAT SAR" at the top, which makes rather more sense:

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKennedy%2F20140319rs02.ASAR.jpg&hash=d5fdbb1d9e95d9c82e8a938d486c8c81)
Title: Re: The Nares Strait thread
Post by: Wipneus on March 31, 2014, 06:58:23 PM
For Terry:

Here is a thermal image of the entry to Nares as seen by Landsat 7 on January 18 2014. The stripes are caused by a malfunction in Landsat 7 sensors. Not good for nice images, but still useful for science.

Since it is thermal, lighter means warmer. The blocking ice is dark, cold and thick. Thinner ice and especially cracks are brighter.

(click the image for the details)
Title: Re: The Nares Strait thread
Post by: Sonia on March 31, 2014, 10:05:03 PM
Wipneus, thank you for digging up that image!  It's fascinating.  January 18th, hm?  For any who might not have been following so closely, that blocking ice wedged in there about January 1st.  You can query the DMI archives around that date to watch it.  I remember I was on the edge of my seat watching because thick ice had been pouring out of the Lincoln Sea.

Of course it may not even matter with the the way the ice in the Lincoln has been cracking lately.  If this dipole keeps up we may not need the Nares to clear the Lincoln of ice!

Also thank you Jim, for posting the radar image and discovering that the DMI radar images are now coming from RADARSAT.
Title: Re: The Nares Strait thread
Post by: TerryM on April 01, 2014, 12:28:56 AM
Thanks Wipneus & all


When the blockage opens we'll see a lot of old MYI heading south without having to round Cap Morris Jesup to make it's escape. I've been taken aback by how robust it's proven to be and don't expect it to last much longer. The constant flow of water below coupled with gale force winds that often blow through the strait will combine at some point to break it and it's not thick enough to bottom out once freed.


I don't expect much from Petermann Glacier this year, but I didn't expect anything in 2012 either. All the experts agree that Humboldt Glacier isn't going anywhere fast but each year I'm fascinated by the icebergs calving into Kane Basin & the silty waters near it's face. If the grounding line proves to be no more than a sand and gravel moraine it doesn't seem impossible for it to be washed out by large fluxes of melt water from below the ice.


The Arctic continues to confound.


Terry
Title: Re: The Nares Strait thread
Post by: Wipneus on April 04, 2014, 10:43:45 AM
For Terry:

Small part of the blocking ice is visible in today's Landsat inbox.

Contrast in this visible is somewhat low, I will fiddle with the contrasts a bit later.

(click if you want the full 15m resolution)
Title: Re: The Nares Strait thread
Post by: Wipneus on April 04, 2014, 11:04:25 AM
Here is an attempt to make the blocking ice easier to see.
Title: Re: The Nares Strait thread
Post by: TerryM on April 05, 2014, 09:17:15 PM
Thanks so much Wipneus!
I assume that we're seeing is ice that is predominantly >2 years old and has been through the grind of compaction on more than one occasion. The relatively smooth surface it presents was not what I expected, though perhaps snow is hiding a more rough, ridged understructure.
Despite there being no evidence of the more normal arch shape it seems to be holding up to the stress. When it first lodged in place in early January I didn't think it would last the week.


The quality of the images you are posting is amazing and allows us a very intimate view of Arctic.
I've been drawn to the changes in fast ice along the Arctic coasts as I think that as these are swept away it they take with them any hope the deniers have of claiming that this is all part of some natural cycle that will soon reassert itself to refreeze the Arctic.
The driftwood located at the head of fjords that had been locked in place for ~5,000 years make mockery of their claims that things were warmer when the Vikings disembarked in Greenland, let alone the claims that it was warmer in the 1930's.
When the melt season has progressed perhaps I'll be able to get the Lat & Long for a particular drift wood sample that has been carbon dated & we could make an image of the region showing open water lapping on the rocks. Even the most oblivious would have to admit that what they are viewing proves that this in no repeating phenomena responding to solar cycles, the AMO or any of the other excuses they typically offer.
 Terry
Title: Re: The Nares Strait thread
Post by: idunno on April 06, 2014, 08:31:03 AM
Some links showing the location of the ice arch compared to recent years...

http://ocean.dmi.dk/arctic/images/MODIS/Kane/20100405TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20100405TERR.jpg)

http://ocean.dmi.dk/arctic/images/MODIS/Kane/small/20110405AQUA.small.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/small/20110405AQUA.small.jpg)

http://ocean.dmi.dk/arctic/images/MODIS/Kane/20120405TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20120405TERR.jpg)

http://ocean.dmi.dk/arctic/images/MODIS/Kane/20130405TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20130405TERR.jpg)

http://ocean.dmi.dk/arctic/images/MODIS/Kane/20140405TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20140405TERR.jpg)

2010 stands out as one heck of an outlier; otherwise, the Nares bridge is much closer to the Lincoln Sea end of the Kane basin than in the other recent years.

IIRC, this area has not been especially warm this winter, so the bridge could prove sturdy; but it has formed in an interesting place.
Title: Re: The Nares Strait thread
Post by: Wipneus on April 06, 2014, 11:38:18 AM

The driftwood located at the head of fjords that had been locked in place for ~5,000 years make mockery of their claims that things were warmer when the Vikings disembarked in Greenland, let alone the claims that it was warmer in the 1930's.
When the melt season has progressed perhaps I'll be able to get the Lat & Long for a particular drift wood sample that has been carbon dated & we could make an image of the region showing open water lapping on the rocks. Even the most oblivious would have to admit that what they are viewing proves that this in no repeating phenomena responding to solar cycles, the AMO or any of the other excuses they typically offer.
 Terry

Yes, I would like to do that. However, this is image is as North as we can hope*) for. I am not sure at what latitude this driftwood was found, but we cannot get all the way to the top of Greenland.

*) as explained before, images from the ascending part of the orbit go a bit further, but those images are extremely rare.
Title: Re: The Nares Strait thread
Post by: Wipneus on April 12, 2014, 09:48:33 AM
A number of extreme northern Greenland Landsat images were added last night. Also the first full image of the block of ice blocking the entrance of the Nares Strait.

Alas, it is cloudy. But i think enough can be seen to justify to post it.

(click the pic for that hi detail image)
Title: Re: The Nares Strait thread
Post by: Jim Hunt on April 12, 2014, 12:14:35 PM
Thanks Wipneus!

Meanwhile at the other end (https://earthdata.nasa.gov/labs/worldview/?switch=arctic&products=baselayers,!MODIS_Aqua_CorrectedReflectance_TrueColor,!MODIS_Aqua_CorrectedReflectance_Bands721,MODIS_Terra_CorrectedReflectance_TrueColor,!MODIS_Terra_CorrectedReflectance_Bands367,!MODIS_Terra_CorrectedReflectance_Bands721~overlays,arctic_graticule_3413,arctic_coastlines_3413&time=2014-04-11&map=-1482944,-1636992,-176320,-888448) of the strait:
Title: Re: The Nares Strait thread
Post by: Wipneus on April 17, 2014, 09:31:58 AM
Large chunks of fast ice are now unfastened downstream of the "Arch".
(source MODIS/Terra NASA Worldview April 16)
Title: Re: The Nares Strait thread
Post by: TerryM on April 17, 2014, 03:51:16 PM
Spring Tide at Cape Defosse Nunavut April 17


Jim Hunt's photo of ice breakup at high tide on another thread shows the effect of the moon on sea ice.


Terry
Title: Re: The Nares Strait thread
Post by: Jim Hunt on April 17, 2014, 07:23:57 PM
Jim Hunt's photo of ice breakup at high tide on another thread

Now it's on this one too!

The latest photo from Martin Hartley (https://twitter.com/MartinRHartley):

(https://pbs.twimg.com/media/BlXwJGMCEAAw7sc.jpg)
Title: Re: The Nares Strait thread
Post by: Jim Hunt on April 19, 2014, 01:55:30 PM
It would be interesting to see a RADARSAT image later today, but in the meantime here's Aqua's view (http://ocean.dmi.dk/arctic/qaanaaq.uk.php) from yesterday:

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FQaanaaq%2F20140418AQUA.jpg&hash=08ef4d1dd01623131d9c823257e0e129)

A large area of ice has vanished over the last 2 or 3 days.
Title: Re: The Nares Strait thread
Post by: Espen on May 02, 2014, 06:51:27 PM
Our seasonal pinhole is showing up again (encircled):
Title: Re: The Nares Strait thread
Post by: Wipneus on May 06, 2014, 09:41:10 AM
Bad luck: we get a rare (night view, but this is the Arctic) Landsat 8 image of the first Nares blockage and then it is clouded.

For what it is worth ( the blocking ice is still in place that is all I can say):
Title: Re: The Nares Strait thread
Post by: Jmo on May 06, 2014, 02:42:22 PM
ASAR from yesterday interesting.
Title: Re: The Nares Strait thread
Post by: Wipneus on May 29, 2014, 10:40:38 AM
Just outside the front door of the Nares Strait the ice has unstuck. First test for the sturdy stopper.

MODIS Terra image 2014-05-28, NASA Worldview: http://1.usa.gov/STftCF (http://1.usa.gov/STftCF)
Title: Re: The Nares Strait thread
Post by: Espen on May 29, 2014, 04:53:06 PM
And getting closer to Nares Strait:
Title: Re: The Nares Strait thread
Post by: TerryM on May 29, 2014, 07:13:39 PM
Another few days should tell just how sturdy our stopper really is.


Terry
Title: Re: The Nares Strait thread
Post by: Neven on May 30, 2014, 09:38:03 AM
Fighting the water in front of you, and then get cracked from behind...

Oh, the irony...

 ;D
Title: Re: The Nares Strait thread
Post by: Espen on June 01, 2014, 08:37:40 PM
We can only be days away from the opening of Nares Strait, the cracks from Lincoln Sea is now entering Nares Strait from the north, another interesting aspect is the "open" sea north of Ellesmere Island near and around Ward Hunt Ice Shelf etc.
Title: Re: The Nares Strait thread
Post by: Wipneus on June 13, 2014, 01:54:53 PM
On this landsat image cracks are appearing now in the ice on both sides of the sturdy stopper.

(click the picture for the full-res image)
Title: Re: The Nares Strait thread
Post by: Buddy on June 13, 2014, 03:23:29 PM
Wipneus:

Do you know how it compares to either 2013 or 2012 at the same time of the month?
Title: Re: The Nares Strait thread
Post by: Jim Hunt on June 13, 2014, 03:56:18 PM
Cracks are appearing now in the ice on both sides of the sturdy stopper.

At least one of which was visible on MODIS yesterday: http://1.usa.gov/1nAZL9X (http://1.usa.gov/1nAZL9X)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 13, 2014, 04:13:32 PM
Wipneus' Landsat image, when enlarged to 1000% :) shows some thin cracks just south (North is pretty much straight upwards on the image, I think) of the "sturdy stopper" and elsewhere, associated with the two large all-the-way-accross cracks.  There is also what might be a healed zig-zag crack west of the stopper.  (Does an expert have a better explanation?  My undergraduate Air Photography class never looked at ice!)

This Landsat image sure beats the available Modis imagry for making enlargements!
Title: Re: The Nares Strait thread
Post by: Wipneus on June 13, 2014, 06:51:00 PM
Wipneus:

Do you know how it compares to either 2013 or 2012 at the same time of the month?

I don't think it is much use to compare individual years. Last year the giant iceberg from Petermann glacier held the ice in Nares strait long together. This year we have this rather unusual big piece of ice creating a blockage.

At least for last year you can look at older messages in this thread. Also watch the posts from  Dr. Andreas Münchow, very informative.

Wipneus' Landsat image, when enlarged to 1000% :) shows some thin cracks just south (North is pretty much straight upwards on the image, I think) of the "sturdy stopper" and elsewhere, associated with the two large all-the-way-accross cracks.  There is also what might be a healed zig-zag crack west of the stopper.  (Does an expert have a better explanation?  My undergraduate Air Photography class never looked at ice!)

This Landsat image sure beats the available Modis imagry for making enlargements!

Yes and this time I choose to post a 30m res image. A 15m res version would be about 12MB, which I think is just too much.
Title: Re: The Nares Strait thread
Post by: Espen on June 14, 2014, 06:51:51 PM
"This year we have this rather unusual big piece of ice creating a blockage."

I don't think this plug is a problem, since it only exported sea ice from the north and probably a bit thicker than the average Nares sea ice.

 
Title: Re: The Nares Strait thread
Post by: Jim Hunt on June 15, 2014, 10:42:32 PM
"The Crack" is now clearly visible (https://earthdata.nasa.gov/labs/worldview/?switch=arctic&products=baselayers,MODIS_Aqua_CorrectedReflectance_TrueColor,!MODIS_Aqua_CorrectedReflectance_Bands721,!MODIS_Terra_CorrectedReflectance_TrueColor,!MODIS_Terra_CorrectedReflectance_Bands367,!MODIS_Terra_CorrectedReflectance_Bands721~overlays,arctic_graticule_3413,arctic_coastlines_3413&time=2014-06-15&map=-386843.670885,-924188.190115,-38171.670885,-737052.190115) on MODIS:

Title: Re: The Nares Strait thread
Post by: Sonia on June 19, 2014, 07:01:27 PM
Did the sturdy stopper just get split in half?  It's pretty cloudy, but a heavy dark line appears in both the latest Aqua and Terra images on Worldview.
Title: Re: The Nares Strait thread
Post by: Patrick on June 19, 2014, 07:33:32 PM
No, that's just the pronounced boundary of a cloud field and its shadow. If you add the 3-6-7 false colour imagery, you'll clearly see the difference between the white clouds and the red/orange ice/snow underneath.
Title: Re: The Nares Strait thread
Post by: Jim Hunt on June 19, 2014, 07:36:49 PM
Did the sturdy stopper just get split in half?

Aqua 7/2/1 (https://earthdata.nasa.gov/labs/worldview/?switch=arctic&products=baselayers,!MODIS_Aqua_CorrectedReflectance_TrueColor,MODIS_Aqua_CorrectedReflectance_Bands721,!MODIS_Terra_CorrectedReflectance_TrueColor,!MODIS_Terra_CorrectedReflectance_Bands367,!MODIS_Terra_CorrectedReflectance_Bands721~overlays,arctic_graticule_3413,arctic_coastlines_3413&time=2014-06-19&map=-418461.603382,-918630.502114,-119709.603382,-743270.502114) suggests it's cloud?
Title: Re: The Nares Strait thread
Post by: Sonia on June 19, 2014, 08:14:50 PM
Whew, sorry for the false alarm, everyone.  Another beginner mistake.  That did seem a rather spectacular way for the breakup to begin, but with occasional ice movement in the Lincoln lately, it did seem possible.

Otherwise, ice has been getting blue around the margins of of Nares but still seems solidly white up and down most of the length, hm?  I try to resist making predictions but I sure like to watch.  It also seems that as the warmup progresses, some patches darken in the radar images.  I make guesses, but I really have no idea what it means.
Title: Re: The Nares Strait thread
Post by: Jmo on June 20, 2014, 05:23:34 AM
I made the same mistake.  To a layman, it sure looks like an unlikely crack!   ;D

Yep, images show in situ melting (eg a small opening of water) behind the bridge, and plenty of blue ice...
Title: Re: The Nares Strait thread
Post by: Polynya88 on June 20, 2014, 03:22:03 PM
Whew, sorry for the false alarm, everyone.  Another beginner mistake.  That did seem a rather spectacular way for the breakup to begin, but with occasional ice movement in the Lincoln lately, it did seem possible.

Otherwise, ice has been getting blue around the margins of of Nares but still seems solidly white up and down most of the length, hm?  I try to resist making predictions but I sure like to watch.  It also seems that as the warmup progresses, some patches darken in the radar images.  I make guesses, but I really have no idea what it means.

The dark patches you see developing on radar images in spring are firstly areas of wet snow where the radar can no longer penetrate the snow (thus can't provide backscatter from the underlying sea ice surface) and instead bounces off away from the radar antennae, and thus you get no return and a dark area on the image. More dark areas will appear as melt progresses, until thaw holes develop in summer and the surface melt water drains away thus revealing the ice surface, then tones will increase to light grey again. I've specialized in interpreting radar imagery for 30 yrs... :)
Title: Re: The Nares Strait thread
Post by: Andreas T on June 20, 2014, 05:45:11 PM
I have tried to read up on this but maybe you can explain this more quickly, polynya88. Why do the ASAR images show a "bright side" and a "dark side" on mountainous regions, the direction seems to change in different passes. I think it is do with the interferometry system using two emitters meaning that what the light / dark intensities show is actually gradients in elevation, i.e. it shows roughness more bright than smooth surfaces. Does that fit with your experience?
Title: Re: The Nares Strait thread
Post by: Polynya88 on June 20, 2014, 06:41:09 PM
I have tried to read up on this but maybe you can explain this more quickly, polynya88. Why do the ASAR images show a "bright side" and a "dark side" on mountainous regions, the direction seems to change in different passes. I think it is do with the interferometry system using two emitters meaning that what the light / dark intensities show is actually gradients in elevation, i.e. it shows roughness more bright than smooth surfaces. Does that fit with your experience?

Radar is a side-looking sensor, so targets that are perpendicular to the look-direction are bright. Also, due to the incidence angle of the imaging beam, the back-side of large features are sometimes in a radar shadow, thus black in  tone. Rough surfaces produce a bright tone, smooth ones not so much. The satellite platform is in a different location/orbit for every image, so the look direction, incidence angle, and azimuth is always changing thus bright targets vary with each pass.
Title: Re: The Nares Strait thread
Post by: Espen on June 21, 2014, 06:40:48 PM
A little action at Nares Strait:
Title: Re: The Nares Strait thread
Post by: Sonia on June 22, 2014, 01:24:29 AM
A little action at Nares Strait:
Yes, I just saw that (and clear as it is, looked at the 7-2-1 image as well.)

I like to speculate about the mechanical forces an ice arch, and one thing I've been wondering is if the Huboldt glacier plays a part.  It's easy to see the ice-water boundary and think of that as the arch, but I wonder in this case if advancement of the glacier doesn't add enough compression to make the "real" arch a broad band stretching from the Humboldt across to Ellesmere.
Title: Re: The Nares Strait thread
Post by: Yuha on June 22, 2014, 11:05:35 AM
A little action at Nares Strait:

There was a visible crack one day earlier and a new crack has appeared about 20 km northward:
Title: Re: The Nares Strait thread
Post by: Andreas T on June 23, 2014, 06:16:18 PM
poor visibility but interesting pattern of break especially regarding Sonia's idea about stresses from Humbold glacier. As the ice edge retreats up Nares strait one would expect ice to push in from the direction of Humboldt. Would be interesting to compare with other years, but I wanted to get this out quickly
 (https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fmap2.vis.earthdata.nasa.gov%2Fimagegen%2Findex.php%3FTIME%3D2014174%26amp%3Bextent%3D-585615.8403314%2C-1115301.0928137%2C-393103.8403314%2C-919717.0928137%26amp%3Bepsg%3D3413%26amp%3Blayers%3DMODIS_Aqua_CorrectedReflectance_TrueColor%2Carctic_coastlines_3413%2Carctic_graticule_3413%26amp%3Bformat%3Dimage%2Fjpeg%26amp%3Bwidth%3D752%26amp%3Bheight%3D764&hash=54b087d4ae6e3ed62d265d218a667fe4)
image from todays aqua modis https://earthdata.nasa.gov/labs/worldview/?switch=arctic&products=baselayers,MODIS_Aqua_CorrectedReflectance_TrueColor~overlays,arctic_graticule_3413,arctic_coastlines_3413&time=2014-06-23&map=-716783.840331,-1180901.092814,-66543.840331,-734949.092814 (https://earthdata.nasa.gov/labs/worldview/?switch=arctic&products=baselayers,MODIS_Aqua_CorrectedReflectance_TrueColor~overlays,arctic_graticule_3413,arctic_coastlines_3413&time=2014-06-23&map=-716783.840331,-1180901.092814,-66543.840331,-734949.092814)
Title: Re: The Nares Strait thread
Post by: nukefix on June 23, 2014, 06:47:23 PM
Radar is a side-looking sensor, so targets that are perpendicular to the look-direction are bright. Also, due to the incidence angle of the imaging beam, the back-side of large features are sometimes in a radar shadow, thus black in  tone. Rough surfaces produce a bright tone, smooth ones not so much.
Yes, and if a digital elevation model is available the inherent distortion in radar images can be corrected in a process called geocoding/orthorectification and radiometric terrain correction. the problem is that the DEMs of northern areas are not always that great.

Quote
The satellite platform is in a different location/orbit for every image, so the look direction, incidence angle, and azimuth is always changing thus bright targets vary with each pass.
Partially correct, the radar orbit repeats itself within an orbital tube of a few hundred meters, so for most practical purposes there are a limited number of imaging geometries, that divide into two groups, namely images from ascending or descending orbits. Ascending and descending scenes map the terrain from two almost opposing directions, so the image distortions are very different in these two types of scenes. With a good DEM the distortions can be corrected, however.
Title: Re: The Nares Strait thread
Post by: Andreas T on June 23, 2014, 10:26:04 PM
clear images for comparison:   
2013
https://earthdata.nasa.gov/labs/worldview/?switch=arctic&products=baselayers,MODIS_Aqua_CorrectedReflectance_TrueColor,MODIS_Terra_CorrectedReflectance_TrueColor~overlays,arctic_graticule_3413&time=2013-06-29&map=-581752.348354,-1005616.801339,-57464.348354,-762416.801339 (https://earthdata.nasa.gov/labs/worldview/?switch=arctic&products=baselayers,MODIS_Aqua_CorrectedReflectance_TrueColor,MODIS_Terra_CorrectedReflectance_TrueColor~overlays,arctic_graticule_3413&time=2013-06-29&map=-581752.348354,-1005616.801339,-57464.348354,-762416.801339)
2012
https://earthdata.nasa.gov/labs/worldview/?switch=arctic&products=baselayers,MODIS_Aqua_CorrectedReflectance_TrueColor,MODIS_Terra_CorrectedReflectance_TrueColor~overlays,arctic_graticule&time=2012-06-30&map=-1151790.630878,-544724.768277,-627502.630878,-301524.768277 (https://earthdata.nasa.gov/labs/worldview/?switch=arctic&products=baselayers,MODIS_Aqua_CorrectedReflectance_TrueColor,MODIS_Terra_CorrectedReflectance_TrueColor~overlays,arctic_graticule&time=2012-06-30&map=-1151790.630878,-544724.768277,-627502.630878,-301524.768277)
ice looks more solid (colder) now but ice edge is further north, of course 2013 had a chunck of Petermann anchoring the ice in Nares
Title: Re: The Nares Strait thread
Post by: Polynya88 on June 24, 2014, 03:02:57 PM
Radar is a side-looking sensor, so targets that are perpendicular to the look-direction are bright. Also, due to the incidence angle of the imaging beam, the back-side of large features are sometimes in a radar shadow, thus black in  tone. Rough surfaces produce a bright tone, smooth ones not so much.
Yes, and if a digital elevation model is available the inherent distortion in radar images can be corrected in a process called geocoding/orthorectification and radiometric terrain correction. the problem is that the DEMs of northern areas are not always that great.

Quote
The satellite platform is in a different location/orbit for every image, so the look direction, incidence angle, and azimuth is always changing thus bright targets vary with each pass.
Partially correct, the radar orbit repeats itself within an orbital tube of a few hundred meters, so for most practical purposes there are a limited number of imaging geometries, that divide into two groups, namely images from ascending or descending orbits. Ascending and descending scenes map the terrain from two almost opposing directions, so the image distortions are very different in these two types of scenes. With a good DEM the distortions can be corrected, however.

Correct you are. I didn't realize the orbit varied by only a few hundred metres. But if we are getting into details anyhow, there is also the issue of signal polarization. The polarization of the sent and received radar signal has a big effect on how things are depicted on an image. Attached is an example of quad polarization radar of an ice island - tone of an ice island can be near black or near white; you pick!
 
Title: Re: The Nares Strait thread
Post by: Espen on June 24, 2014, 04:39:45 PM
More cracks in Nares Strait around Hans Ø ( Hans Island)

Please click on image to enlarge!
Title: Re: The Nares Strait thread
Post by: Sonia on June 26, 2014, 07:15:37 PM
The remaining arch this morning struck me as looking like a flying buttress.  Now, we don't expect it to hold back Ellesmere Island from collapsing on Greenland, but if you pick the Humboldt as your frame of reference, maybe Ellesmere does seem to be pressing in?

There's a nice cloud-free view of the Nares from space currently.  A few new small cracks are visible.
Title: Re: The Nares Strait thread
Post by: Espen on June 27, 2014, 07:51:30 PM
They're Coming to Take Me Away, Ha-Haaa:



Please click on image to enlarge!
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 27, 2014, 09:07:43 PM
Quote
They're Coming to Take Me Away, Ha-Haaa:
I'm rather fond of side B of the 45 rpm record on which that song was released. ;D

http://en.wikipedia.org/wiki/They're_Coming_to_Take_Me_Away,_Ha-Haaa! (http://en.wikipedia.org/wiki/They're_Coming_to_Take_Me_Away,_Ha-Haaa!)
Title: Re: The Nares Strait thread
Post by: Patrick on June 27, 2014, 10:50:44 PM
Nice little detail in that last image: Hans Island produces a subtle vortex street, thereby indicating the northern wind over Nares Strait.
Title: Re: The Nares Strait thread
Post by: TerryM on June 29, 2014, 09:00:18 AM
Han Island Weather.
http://dalriada.sams.ac.uk/aws_hans/ (http://dalriada.sams.ac.uk/aws_hans/)


Terry
Title: Re: The Nares Strait thread
Post by: Espen on June 29, 2014, 09:58:42 AM
Nice little detail in that last image: Hans Island produces a subtle vortex street, thereby indicating the northern wind over Nares Strait.

That is Franklin Ø, Hans Ø is bit further north:

https://mapsengine.google.com/map/edit?mid=zbdKKg4fRHYo.kjkUmepfXc9A
Title: Re: The Nares Strait thread
Post by: Espen on June 29, 2014, 12:11:19 PM
Final break up is underway:
Title: Re: The Nares Strait thread
Post by: Sonia on June 29, 2014, 05:35:04 PM
Final break up is underway:
Gosh, what terrible image!  There must be some problem in the decoding or reconstructing or something.
Title: Re: The Nares Strait thread
Post by: johnm33 on June 29, 2014, 06:39:50 PM
There's a clear shot of it on worldview http://1.usa.gov/1ofJCqP (http://1.usa.gov/1ofJCqP) take a look at that glacier on Ellesmere too.
Title: Re: The Nares Strait thread
Post by: Espen on June 29, 2014, 06:45:43 PM
Final break up is underway:
Gosh, what terrible image!  There must be some problem in the decoding or reconstructing or something.

It is a prelim image.
Title: Re: The Nares Strait thread
Post by: Espen on June 29, 2014, 07:43:19 PM
Here is a better one:

Title: Re: The Nares Strait thread
Post by: Sonia on June 29, 2014, 08:40:05 PM
That's better  :)  What an amazing catastrophe.  I know, it's an annual thing, but it's still awesome.  Neven's Nares breakup special edition should be soon now.  But there's still a little suspense in how long the remaining ice will last.  I think it was last year that an arch just below the Hall Basin hung on for several days before succumbing to the inevitable.  Earlier this week I looked at the little crack that formed at Franklin Island and wondered if the arch it formed would be sturdy.  But nope! today's images show a whole succession of arch-shaped cracks blowing right by it.  It's also fascinating to me that this breakup happens in the "white" ice more than in the "blue" ice.  Somehow I imagine the blue ice softer.  Maybe that's just it.  Maybe it gives a little, while the more brittle ice is forced to crack.

The suspense will shift soon to the Lincoln.  MYI was being lost at an astonishing rate last year before the "sturdy stopper" ended the export season.  Since then there was that big fracturing event in the Lincoln, and most recently polynyas have appeared on either side of the Lincoln.
Title: Re: The Nares Strait thread
Post by: Neven on June 29, 2014, 09:29:01 PM
Neven's Nares breakup special edition should be soon now. 

I will try to put something up at the end of the week. I invested a lot into the latest ASI update, so I want that to stand for a while.
Title: Re: The Nares Strait thread
Post by: Espen on June 29, 2014, 09:53:52 PM
This image gives a better view over the situation, cracks now passed Hans Ø:
Title: Re: The Nares Strait thread
Post by: Patrick on June 30, 2014, 03:29:23 PM
Nice little detail in that last image: Hans Island produces a subtle vortex street, thereby indicating the northern wind over Nares Strait.
That is Franklin Ø, Hans Ø is bit further north:

https://mapsengine.google.com/map/edit?mid=zbdKKg4fRHYo.kjkUmepfXc9A
Hmm, there seems to be some kind of misunderstanding. I think we both have the correct spot as Hans Island in our mind. So just to clarify I added some labels to the satellite image, the vortex street is marked by red lines.
Title: Re: The Nares Strait thread
Post by: Espen on July 02, 2014, 04:46:57 PM
Another brick in the wall:
Title: Re: The Nares Strait thread
Post by: Andreas T on July 08, 2014, 03:52:17 PM
looking for something else I was very surprised to see a noticeable temperature difference (If I understand band31 correctly) between water and ice at the ice arch and in front of Humboldt glacier.
http://1.usa.gov/1qf4kHl (http://1.usa.gov/1qf4kHl)
cranking up the contrast makes it clearer ( I include the visible image but toggling between the two is easier on worldview)
Usually I find ice and water indistinguishable in band31 but here water flowing under the arch seems cooler (darker) than the ice whereas slightly further south there is warmer (lighter) water right between the ice floes. Elsewhere I would interpret this as river water but here the most likely source would be meltwater exiting below the glacier?
Title: Re: The Nares Strait thread
Post by: Jim Hunt on July 12, 2014, 02:00:40 AM
It's difficult to be certain through the clouds, but it looks like the "sturdy stopper" is now sporting some cracks:

http://1.usa.gov/1rfbvk1 (http://1.usa.gov/1rfbvk1)

Flip to Aqua to see some cracks in the Lincoln Sea also.
Title: Re: The Nares Strait thread
Post by: Sonia on July 12, 2014, 07:54:32 AM
It's difficult to be certain through the clouds, but it looks like the "sturdy stopper" is now sporting some cracks:

http://1.usa.gov/1rfbvk1 (http://1.usa.gov/1rfbvk1)

Flip to Aqua to see some cracks in the Lincoln Sea also.

Oh, very good catch.  You know, I had spotted the cracks in the Aqua image but didn't bother to try to look past the clouds in the Terra image.  Taking a closer look now, and blinking against images of a few days ago, the ice not only has new cracks but has noticeably bulged to the south.  (Sorry I don't have an animation to show.)  Hopefully we'll get a better look in several hours.
Title: Re: The Nares Strait thread
Post by: Espen on July 12, 2014, 09:40:35 AM
Here is a far more detailed image from Landsat:
Title: Re: The Nares Strait thread
Post by: Jim Hunt on July 12, 2014, 12:32:03 PM
Oh, very good catch.

Thanks Sonia, and Espen. Where do you get hold of such recent Landsat images?

Actually I was prompted to look closely by Bob Wallace's intriguing thickness map (http://forum.arctic-sea-ice.net/index.php/topic,778.2100.html)

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi619.photobucket.com%2Falbums%2Ftt275%2FBob_Wall%2FNares.gif&hash=72c8a5484c79ca462742f122fcb47942)
Title: Re: The Nares Strait thread
Post by: Espen on July 12, 2014, 12:48:34 PM
Jim,

You can download from here: http://earthexplorer.usgs.gov/ (http://earthexplorer.usgs.gov/)
Title: Re: The Nares Strait thread
Post by: Espen on July 12, 2014, 01:11:10 PM
Very soon Nares Strait will be open, big cracks are seen in front of Petermann Fjord:
Title: Re: The Nares Strait thread
Post by: Jim Hunt on July 12, 2014, 01:50:43 PM
You can download from here: http://earthexplorer.usgs.gov/ (http://earthexplorer.usgs.gov/)

Thanks Espen. I've been using LandsatLook. Sounds like the obvious place, but there seems to be much more available via EarthExplorer
Title: Re: The Nares Strait thread
Post by: Espen on July 12, 2014, 04:25:54 PM
Now the cracks entered Petermann Fjord:

Please click on image to enlarge!

Title: Re: The Nares Strait thread
Post by: johnm33 on July 12, 2014, 05:30:39 PM
I suspect all the recent cracks are full moon /extreme tides but the ice looks like broken glass all the way into Lincoln. Soon be gone. Good catch.
Title: Re: The Nares Strait thread
Post by: Jim Hunt on July 13, 2014, 01:10:05 AM
Things are certainly starting to move: http://1.usa.gov/1sMRiCk (http://1.usa.gov/1sMRiCk)
Title: Re: The Nares Strait thread
Post by: ghoti on July 13, 2014, 03:29:28 AM
The Arctic Cap HYCOM thickness graphics seem to suggest the ice around the top of the Nares is 5m thick. Is that possible? The current images don't give the impression of such massive ice structure. Of course viewed from space you can't see thickness but it looks so fragile.
Title: Re: The Nares Strait thread
Post by: Jim Hunt on July 13, 2014, 10:57:10 AM
Here's a view from space that suggests that the ice around the top of the Nares isn't all 5m thick.

This is RADARSAT (http://ocean.dmi.dk/arctic/lincoln.uk.php) from June 11th:

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FLincoln%2F20140611rs02.ASAR.jpg&hash=f2f199c5f090187d0147b50e3afeba2e)

By way of comparison this is from yesterday:

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FLincoln%2F20140712rs02.ASAR.jpg&hash=9461195cecb58b83e043c61c814b508b)
Title: Re: The Nares Strait thread
Post by: Andreas T on July 13, 2014, 11:24:46 AM
The radar images can be ambiguous for interpretation, they do not show thickness directly. I think the two images you show demonstrate that. Note how the small icecaps on the mountains change from light in the June image to dark in the july image. Maybe polarization or something is different in these images
What definitely shows age of the ice and indicates thickness through surface temperature are these IR images from when the stopper moved into place this winter:
top 2013/12/30 http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/201312301205.NOAA.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/201312301205.NOAA.jpg)
bottom 2014/01/09
http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/201401091336.NOAA.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/201401091336.NOAA.jpg)
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FLincoln%2F201312301205.NOAA.jpg&hash=07e76637e2702b2c978d891a932f917b)
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FLincoln%2F201401091336.NOAA.jpg&hash=033d76df61498552ba721866542aa3b0)
The images also show how the ice is always full of older cracks which allow it to move and are renewed by that movement. So ice average icethickness (better to look at icebridge data than HYCOM for that) is giving a measure of the thickness of shifting floes not a solid slab of ice.
The movement also produces ridges by tilting floes sideways which add  to the average thickness.
Title: Re: The Nares Strait thread
Post by: Andreas T on July 13, 2014, 11:45:06 AM
another thing: the older floes from the IR image are recognizable in the ASAR from june and in the visible from yesterday either through different ice structure (radar) or greater snow depth (whiter appearance in visible because meltponds take longer to form?)
Title: Re: The Nares Strait thread
Post by: Espen on July 13, 2014, 02:29:48 PM
The Nares Express is ready:

Please click on image to enlarge!
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 13, 2014, 02:55:50 PM
The southern (southwestern actually) end is also breaking up.   Hans Island is just covered by the cloud bank where the recent ice bridge held for a few days.  Ice has broken up 10 or 15 kilometers northwards of there.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKennedy%2F20140712TERR.jpg&hash=103837648941eb76336b352f2480c8fa)
Title: Re: The Nares Strait thread
Post by: TerryM on July 13, 2014, 08:34:16 PM
It's interesting that although the "Stopper" is fractured, it's still more or less in place.
Is the Lincoln Sea ice melting away in a polynia as opposed to being advected through Nares?
Terry
Title: Re: The Nares Strait thread
Post by: Andreas T on July 13, 2014, 11:06:56 PM
if you toggle between terra and aqua images on worldview http://1.usa.gov/1sbE44w (http://1.usa.gov/1sbE44w)
you see there is quite a bit of movement of the stopper within some hours. On the Lincoln side of it is first year ice which formed only at the end of december but doesn't look like melting away yet.
Title: Re: The Nares Strait thread
Post by: Jim Hunt on July 13, 2014, 11:11:00 PM
I was just typing much the same as Andreas. The "stopper" is clearly moving. Compare the last 3 days on Terra:
Title: Re: The Nares Strait thread
Post by: Andreas T on July 14, 2014, 09:40:01 AM
looking back at the thread last year:
Here's the latest, lot's of disintegration!
http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2013194171000-2013194171500.250m.jpg (http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2013194171000-2013194171500.250m.jpg)

Thanks to Phil, I thought it would be quite up there today, but obviously not:
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fforum.arctic-sea-ice.net%2Findex.php%3Faction%3Ddlattach%3Btopic%3D176.0%3Battach%3D2643%3Bimage&hash=3b1db7e6631069a05d1a8f3a87365d55)
Cracks developed close to Petermann Fjord, this afternoon.
Title: Re: The Nares Strait thread
Post by: Jmo on July 15, 2014, 02:02:36 AM
Nares express now well and truly open for business.  Modis images on DMI for 13/7 and 14/7 show incredible breakup and speed of flow.  I know it happens every year, but it's pretty speccy to see.  Seems like lots of loose fragments to export as you look north...
http://ocean.dmi.dk/arctic/kennedy.uk.php (http://ocean.dmi.dk/arctic/kennedy.uk.php)
Title: Re: The Nares Strait thread
Post by: Espen on July 20, 2014, 10:23:08 PM
Nares Strait is almost like when IKEA is opening one of their shops in a new market, the run is from above!
Title: Re: The Nares Strait thread
Post by: Andreas T on July 20, 2014, 11:12:28 PM
comparing the 18th and 20th July images, looking for recognizable floes
http://1.usa.gov/1sBRwPq (http://1.usa.gov/1sBRwPq)
http://1.usa.gov/1sBRBCK (http://1.usa.gov/1sBRBCK)
Hall Basin looks like the IKEA carpark , its so congested nothing is getting in or out
Title: Re: The Nares Strait thread
Post by: ghoti on July 21, 2014, 06:00:16 AM
Nothing may be getting out but much of it is moving south. Seems like there are four floes roughly 10km in size in the southern 60km. They look like some of them moved around 5km in the 2 days. The southern most one did seem to move north though.
Title: Re: The Nares Strait thread
Post by: Sonia on July 22, 2014, 10:38:47 PM
Ice really is moving north through the Robeson Channel currently.  Clouds over the Nares have made ice watching frustrating lately so I was eagerly awaiting today's radar images on the DMI site.  They're here now, and though maddingly missing data across the Hall basin, reveal interesting ice movement.

If you blink against images from the 19th you see that while ice (including remnants of the sturdy stopper) is lazily floating south through the Kennedy Channel, it is quite clearly moving north through the Robeson!  That should ease the Ikea traffic jam, if we could only see it.

Looking farther up into the Lincoln Sea shows a rip where is ice is moving north on the west side of the sea and south on the east side.  Check your favorite source of surface wind data (I really like earth.nullschool.net) for insight into this.  Brisk winds are blowing straight up the Robeson and west Lincoln Sea driving this ice return.  A little farther south in the Kennedy, winds are not as strong and apparently do not overcome the drag of the current flowing south.
Title: Re: The Nares Strait thread
Post by: Jmo on July 23, 2014, 01:45:58 AM
Certainly still flowing from the "blockage" south, from what I can see in DMI Terra/Aqua images 20-22 July. Ice movement and/or in situ melting, as well as a colour change to stronger blues in remaining ice.  Petermann fiord appears to be clearing out rapidly also. Not strange, but interesting.
Title: Re: The Nares Strait thread
Post by: TerryM on July 23, 2014, 07:39:00 PM
Sonia
There are two currents in Nares Strait and like most Arctic passages the traffic stays to the right. The southerly current is usually much larger and stronger. At least two gyres occur, one in Kane Basin and the more prominent in Hall Basin where large chunks of ice will often go around 2 or 3 times before breaking free.
Winds in the steep walled canyon can be extreme as Dr. Munchow discovered when his anemometer was destroyed, but thick ice is usually directed more by current than by wind.


Terry

Title: Re: The Nares Strait thread
Post by: Espen on July 23, 2014, 07:57:13 PM
Terry, do we have any info regarding the P2s?
Title: Re: The Nares Strait thread
Post by: DaddyBFree on July 25, 2014, 01:43:45 AM
Terry, do we have any info regarding the P2s?

Hi Espen,
I lost track of half of it (Maybe broke up), but the other half was near Lancaster Sound and Pond Inlet (NW Baffin Bay) yesterday.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fscreencast.com%2Ft%2F5RWHip8uG&hash=305062c18a519c6642db813211263fcf)
Title: Re: The Nares Strait thread
Post by: Espen on July 25, 2014, 02:20:26 AM
Thanx Daddy! ;)
Title: Re: The Nares Strait thread
Post by: DaddyBFree on July 25, 2014, 04:41:29 PM
My pleasure; and if anyone tracked any fragments from the other half, I would be curious to see where they ended up :)
Title: Re: The Nares Strait thread
Post by: Andreas Muenchow on July 28, 2014, 06:01:00 PM
My pleasure; and if anyone tracked any fragments from the other half, I would be curious to see where they ended up :)

The Canadian Ice Service is tracking as many of the ice islands as possible. The attached is what I received last week, more detail in RadarSat, but those data/imagery are not easily shared as it may violate copyrights.

Edit: "Kane Basin" should read "Lincoln Sea" in the circled bit at the northern edge. It probably indicates glacier ice from either Ryder or Steensby Glaciers that discharge into the Arctic Ocean to the north of Nares Strait.

Title: Re: The Nares Strait thread
Post by: Jim Hunt on July 28, 2014, 06:21:13 PM
Thanks Andreas. That makes life much easier!

http://1.usa.gov/X4qlzX (http://1.usa.gov/X4qlzX)

Title: Re: The Nares Strait thread
Post by: DaddyBFree on August 01, 2014, 03:21:47 PM
Thanks Andreas! I have tracked some using Worldview, but it gets difficult at times. 8)
Title: Re: The Nares Strait thread
Post by: Phil. on August 01, 2014, 04:41:08 PM
Nice clear view on MODIS today:
http://lance-modis.eosdis.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2014213110000-2014213110500.250m.jpg (http://lance-modis.eosdis.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2014213110000-2014213110500.250m.jpg)
Title: Re: The Nares Strait thread
Post by: oren on August 01, 2014, 05:41:28 PM
Great image
Title: Re: The Nares Strait thread
Post by: solartim27 on August 05, 2014, 08:31:50 PM
First clear day in a while, looks like there's another stopper
http://lance-modis.eosdis.nasa.gov/imagery/subsets/?subset=Arctic_r03c03.2014217.terra (http://lance-modis.eosdis.nasa.gov/imagery/subsets/?subset=Arctic_r03c03.2014217.terra)
Title: Re: The Nares Strait thread
Post by: solartim27 on August 05, 2014, 10:24:13 PM
Nah, just a cloud.
Title: Re: The Nares Strait thread
Post by: Espen on November 30, 2014, 08:27:46 PM
The "Nares Express" is still moving:
Title: Re: The Nares Strait thread
Post by: A-Team on December 01, 2014, 12:56:09 PM
Whoa ... not so easy to track individual floes just a few days apart. A lot of break-up in the narrows. I've added a few more floes with fairly high confidence but still cannot account for the origin of everything in the Strait.

The idea with the translucent gradients was to define a directional polarity axis in the 'before' flow so any rotation would be evident when the gradient was applied in the same orientation to the 'after' floe. However I didn't manage to do this very consistently.
Title: Re: The Nares Strait thread
Post by: Polynya88 on December 01, 2014, 02:49:19 PM
The break-up of floes isn't too surprising. These floes are all conglomerate, and the "glue" between multi-year pieces is only thin First-year yet, so it doesn't take much to fracture them.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on December 01, 2014, 09:44:36 PM
I note the Dec 1 DMI Sentinel-1 image (http://ocean.dmi.dk/arctic/kennedy.uk.php (http://ocean.dmi.dk/arctic/kennedy.uk.php)) shows the big 'red/orange colored' floe has moved quite a bit (5 or 8 km? since Nov 30) .  I hope to keep watching in order to see where it breaks up, slips through or gets stuck (or combinations of the three).
Title: Re: The Nares Strait thread
Post by: Espen on December 03, 2014, 05:12:25 PM
Still on the move: ( Nov 30 - Dec 1 - Dec 2 )
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on December 04, 2014, 05:25:11 PM
It sure is 'steaming' along: about 25 km in one day, on 2014-12-03 it was in Hall Basin off Ellesmere Island's Lady Franklin Bay (functionally opposite Petermann Glacier).  Today it will likely glide past Joe Island.  On Friday (at this rate) it will run into Hans Island and stop/split/splinter.  Hmmm, if a block of ice hits a rock hard enough, will any steam be produced? ;D

See place name map at https://mapsengine.google.com/map/viewer?mid=zbdKKg4fRHYo.kugA5VIgp5ec  (https://mapsengine.google.com/map/viewer?mid=zbdKKg4fRHYo.kugA5VIgp5ec) in the Forum's "Google Maps with place names Greenland" thread - http://forum.arctic-sea-ice.net/index.php/topic,277.0.html (http://forum.arctic-sea-ice.net/index.php/topic,277.0.html).  DMI radar (Sentinel-1) images available at http://ocean.dmi.dk/arctic/kennedy.uk.php (http://ocean.dmi.dk/arctic/kennedy.uk.php)

Thanks for the animations, A-Team and Espen!
Title: Re: The Nares Strait thread
Post by: Espen on December 04, 2014, 05:37:39 PM
I wonder if there are any quake sensors at Hans Ø?
Title: Re: The Nares Strait thread
Post by: Espen on December 04, 2014, 05:46:07 PM
The large sea-ice island was reduced in size between Dec. 2 and Dec. 3:
Title: Re: The Nares Strait thread
Post by: Espen on December 05, 2014, 06:44:35 AM
Even more minimized, notice the "new" large piece entering the Strait (red arrow):

Title: Re: The Nares Strait thread
Post by: A-Team on December 05, 2014, 12:31:58 PM
indeed, it looks to me like word salad. Could spell trouble?
Title: Re: The Nares Strait thread
Post by: Laurent on December 05, 2014, 02:49:39 PM
Do we have an idea of the usual speed of the ice at that time ? It sounds to me very fast !?
Title: Re: The Nares Strait thread
Post by: Polynya88 on December 05, 2014, 04:11:50 PM
Back a number of years ago, a great author (Moira Dunbar) came up with the attached table. It came from this document http://pubs.aina.ucalgary.ca/arctic/Arctic32-4-283.pdf (http://pubs.aina.ucalgary.ca/arctic/Arctic32-4-283.pdf)
At a high of .8m/sec. historically, current drift rates in Nares St. look normal when no ice bridges are present or forming.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on December 05, 2014, 05:11:29 PM
So much for my prediction skills:  only the largest remaining piece of A-Team's "E" got past Joe Island yesterday.  It looks like "S" ran into Cape Baird causing "E" to rear-end "S", and the stress of the interaction broke "E" into pieces. The most recognizable (and 2nd largest) piece of “E” has a persistent dark mark on the image; it was on the rear port-side (east) part of “E” before the collision and remained (on Dec 4) in Hall Basin just off of Petermann Fjord and east of Joe Island. 

Today’s drama:  Will this ‘marked piece of “E”’ get stuck behind Joe Island or will it be drawn back into the flow?  Saturday:  Will the ‘largest remaining piece of “E”’ get by Hans Island on Saturday? (It was obviously slowed down by the collision – yesterday’s prediction of a Friday arrival will not come to pass.)  And how long will Espen’s “new large piece” keep its hexagon shape?

Petermann Fjord is about 15 km wide, so pre-collision “E” was about 30 km long.  It moved about 45 km between the Dec 2 and Dec 3 Sentinel-1 images – nearly 2 km/hr!  The leading edge of the ‘largest remaining piece of “E”’ on Dec 4 was about 35 km downstream from where it was on Dec 3.  The Dec 4 location is about 55 km upstream from Hans Island.  I presume the Sentinel-1 images are spaced approximately 24 hours apart.

Figure 3 in Kwok (2005 “Variability of Nares Strait ice flux”) http://rkwok.jpl.nasa.gov/publications/Kwok.2005e.GRL.pdf (http://rkwok.jpl.nasa.gov/publications/Kwok.2005e.GRL.pdf) (if I read it right) indicates ice velocities in November & December up to 40 km/day at the northern (actually NE) end of Nares Strait.  Ice seems to speed up once it gets into the strait; “E” did.  (Ice bridges form – except for 2006-7 – between November and March.)

Edit:  According to an internet calculator:
.83 m/sec  = 72 km/day
.59 m/sec = 51 km/day
.24 m/sec = 21 km/day

Title: Re: The Nares Strait thread
Post by: Espen on December 05, 2014, 05:21:22 PM
indeed, it looks to me like word salad. Could spell trouble?

Wonder what is coming up next! ;)
Title: Re: The Nares Strait thread
Post by: viddaloo on December 05, 2014, 05:26:33 PM
(Ice bridges form – except for 2006-7 – between November and March.)

Thanks, Tor Bejnar. Do you think that's key to the 2007 'success' and record lows?

PS: Per date (December 4th), 2006 (soon to be 07) has the lowest extent of all years this century.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on December 05, 2014, 05:50:46 PM
Quote
I wrote: (Ice bridges form – except for 2006-7 – between November and March.)
Viddaloo wrote: Do you think that's key to the 2007 'success' and record lows?
Obviously it is a piece of the puzzle; a great deal more ice was exported through Nares Strait that winter, spring & early summer than in any other year (although small compared with Fram Strait export).  I wonder if this Nares export somehow loosened up remaining ice in nearby parts of the Arctic allowing freer motion.
Title: Re: The Nares Strait thread
Post by: Espen on December 05, 2014, 06:01:26 PM
Quote
I wrote: (Ice bridges form – except for 2006-7 – between November and March.)
Viddaloo wrote: Do you think that's key to the 2007 'success' and record lows?
Obviously it is a piece of the puzzle; a great deal more ice was exported through Nares Strait that winter, spring & early summer than in any other year (although small compared with Fram Strait export).  I wonder if this Nares export somehow loosened up remaining ice in nearby parts of the Arctic allowing freer motion.

There is also a lot of activity around the "Flade Isblink Corner" (North East Greenland).
Title: Re: The Nares Strait thread
Post by: Laurent on December 05, 2014, 07:14:45 PM
Thanks, according to your link Tor bejnar in december the average speed is around 12 km/day with a max of 40 km/day. So with 45 km/day with are in very high gear !
Title: Re: The Nares Strait thread
Post by: Espen on December 06, 2014, 03:32:58 PM
Nares Strait Nov30 - Dec 5 2014:
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on December 08, 2014, 04:00:46 AM
On Friday I wrote:
...
Today’s drama:  Will this ‘marked piece of “E”’ get stuck behind Joe Island or will it be drawn back into the flow?  Saturday:  Will the ‘largest remaining piece of “E”’ get by Hans Island on Saturday? (It was obviously slowed down by the collision – yesterday’s prediction of a Friday arrival will not come to pass.)  And how long will Espen’s “new large piece” keep its hexagon shape?
...
The 'marked piece of “E”’ did get stuck behind Joe Island, and the ‘largest remaining piece of “E”’ appears to have disintegrated upon colliding with Hans Island.  I don't know if there was any steam, though ;D

Espen’s “new large piece” lost it's top upon entering the strait.

Laurent, the chart showing monthly average ice speed (and extremes) is the speed only at the entrance to the strait and does not say anything about average ice speed through Hall Basin, etc.  Watching Espen's animations (and past experience), the ice mostly speeds up after it enters Nares Strait.  (I've seen ice get caught in an anti-clockwise eddy in Kane Basin.)

Title: Re: The Nares Strait thread
Post by: Espen on December 08, 2014, 04:47:59 AM
Dec 5 - Dec 7 2014:

Title: Re: The Nares Strait thread
Post by: Wipneus on December 17, 2014, 10:30:58 AM
It is too long since the last animation. Here are the latest (Dec 9-16) images of ice entering the Strait. The last two frames suggest the first traditional arch is appearing.
Title: Re: The Nares Strait thread
Post by: Wipneus on December 19, 2014, 07:18:01 AM
The arch holds.
Title: Re: The Nares Strait thread
Post by: oren on December 19, 2014, 08:40:50 AM
Wipneus, thanks for posting. Really impressive to watch this in real time
Title: Re: The Nares Strait thread
Post by: Espen on December 19, 2014, 06:06:35 PM
Just a follow up on Wipneus nice work:
Title: Re: The Nares Strait thread
Post by: Espen on December 20, 2014, 11:23:04 AM
The arch is a reality:
Title: Re: The Nares Strait thread
Post by: Espen on December 20, 2014, 11:27:05 AM
It will be interesting to see if the the current is strong enough and the Strait be emptied from old debris and new sea ice be formed?
Title: Re: The Nares Strait thread
Post by: Neven on December 20, 2014, 10:53:20 PM
Nice stuff, gentlemen. Nares really is one of the coolest spots in the Arctic. Maybe not the most important, but definitely one of the coolest.
Title: Re: The Nares Strait thread
Post by: Espen on December 21, 2014, 10:58:22 AM
Nice stuff, gentlemen. Nares really is one of the coolest spots in the Arctic. Maybe not the most important, but definitely one of the coolest.

Neven you right, Nares Strait is probably the most exciting site sea ice wise!
Title: Re: The Nares Strait thread
Post by: A-Team on December 21, 2014, 09:24:02 PM
Dubious shape for arch strength but does seem to be holding. Current transport below is still strong.
Title: Re: The Nares Strait thread
Post by: Wipneus on December 24, 2014, 07:01:59 AM
DMI missed some data (they are available as Gigabyte downloads from ESA) but the latest image shows the arch holds, square shaped as it is.
Title: Re: The Nares Strait thread
Post by: Espen on December 24, 2014, 12:43:47 PM
The seasonal clearing sale is almost over:
Title: Re: The Nares Strait thread
Post by: A-Team on December 24, 2014, 11:11:21 PM
Looked a bit different on 24.Dec.13 and 23.Dec.12. Seems to me this is an arch with resistive strength only to the NW.
Title: Re: The Nares Strait thread
Post by: Shared Humanity on December 25, 2014, 03:54:15 PM
One thing that is striking with these images is the remarkably fractured ice that is north of the arch. The floes appear to be quite small compared to 2012 and 2013.
Title: Re: The Nares Strait thread
Post by: Sigmetnow on December 26, 2014, 04:21:13 PM
Ice-student question:
How much of the dark bits above the arch is surface melt?
Title: Re: The Nares Strait thread
Post by: Espen on December 26, 2014, 04:51:51 PM
Ice-student question:
How much of the dark bits above the arch is surface melt?

Not melt, but newly formed sea ice.
Title: Re: The Nares Strait thread
Post by: A-Team on December 26, 2014, 06:25:48 PM
Not representing that the animation below does a great job of enlarging and rotating the blurry 26 Dec MODIS 06:23 am to overlay the 25-12-2014 Sentinel but some apparent changes do bear watching for in today's Sentinel...
Title: Re: The Nares Strait thread
Post by: Sigmetnow on December 26, 2014, 06:33:42 PM
Ice-student question:
How much of the dark bits above the arch is surface melt?

Not melt, but newly formed sea ice.

So...  Sea ice, near sea level, between the tall floes?

Thanks!
Title: Re: The Nares Strait thread
Post by: Espen on December 26, 2014, 08:32:02 PM
Nares is slowing down, the water is getting harder as they say in Thai (Nam Kheng/ Hard Water (ice)):
Title: Re: The Nares Strait thread
Post by: Espen on December 27, 2014, 08:05:54 PM
It may be my last post this year, heading for New Year Celebration at Brandenburger Tor:

Title: Re: The Nares Strait thread
Post by: Wipneus on December 29, 2014, 08:07:29 AM
Winds turned from north to south and now north again. It matters little to our arch.
Title: Re: The Nares Strait thread
Post by: Wipneus on December 29, 2014, 08:13:44 AM
Downstream in the Kane basin a channel is visible through which the remaining ice floes move toward Baffin Bay. A curious white glitch in the north suddenly paints the darker thin ice between the thick floes pure white.
Title: Re: The Nares Strait thread
Post by: Espen on December 29, 2014, 10:18:24 AM
Update from Berlin (the wifi is ok ;)), yes the formation of ice? South of Franklin Ø seems strange, and just in 24 hours?
And the Strait north of Franklin Ø up the Arch at Lincoln Sea is almost clear of old sea ice (+3 months)
Title: Re: The Nares Strait thread
Post by: Sonia on December 29, 2014, 07:15:51 PM
A curious white glitch in the north suddenly paints the darker thin ice between the thick floes pure white.

... the formation of ice? South of Franklin Ø ...

I interpret that as more of a glint than a glitch.  Sometimes a patch will light up like that in one image and then be back to normal in the next.  See for example http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20141223s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20141223s01a.ASAR.jpg) where an image stitch seam cuts right across a similar glint south of Franklin.
Title: Re: The Nares Strait thread
Post by: Sonia on December 29, 2014, 07:50:19 PM
I'm still watching for another arch to form, farther down.  I've only been watching the arctic ice since the sensational losses of 2012 but I've gotten the impression that Smith Sound is historically the typical place for an arch.  The last couple of years we've seen arches more up into the Kane Basin but either way, most of the Nares is then immobilized for the winter.  Our arch in the Lincoln this year looks precarious.  It seems not that uncommon for the thick ice in the Lincoln to get squished around or see big cracking events.  I can imagine either of these collapsing the arch and restarting export.  Last week the arch survived as some cracks ran across the norther Lincoln Sea but didn't spread further south.  This week I'm watching for the weather to maybe increase pressure on the ice and possibly squish it some.  Meanwhile ice is flowing relatively freely down the length of the Nares.  Somehow conditions need to change to slow the (now mostly young) ice enough to let another arch solidify.
Title: Re: The Nares Strait thread
Post by: Wipneus on December 31, 2014, 08:45:08 AM
Arch holding despite the strong NE wind that blow through the Strait. Look at the entrance of the channel to the Peterman glacier: some ice floes that had parked there broke loose in the last frame.

(skipped the frame of Dec 29, click to anmiate)
Title: Re: The Nares Strait thread
Post by: Wipneus on December 31, 2014, 03:55:16 PM
For previewing purposes ESA provides separate so called "quick-look" images that come with their giga-byte downloads. Where the data has dual polarizations, the quick-look images are false colored: Horizonatl for Red, Vertical for Green and and average for Blue, or at least so they say.

Some of these images are beautiful at their own, like this one showing Smith Sound between Kane Basin and Baffin Bay. The "fast" ice in the Kane basin (as elsewhere in the Nares Strait) seems to be under stress, an ice float broke off and several cracks are visible.

(click for the bigger picture)
Title: Re: The Nares Strait thread
Post by: Espen on December 31, 2014, 05:04:17 PM
Wipneus,

You are really digging into this new goldmine provided by ESA

Happy New Year from Berlin! ;)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on December 31, 2014, 05:21:06 PM
One aspect of Nares Strait ice export I hadn't realized is associated with the lack of a second ice bridge.  Right now there is an ice bridge only in the Lincoln Sea.  The Sentinel images show sea ice forming just southwest of the bridge (at least, that is what I believe I am seeing!), but without another ice bridge it is mostly carried southward by the flowing water.  As long as a second ice bridge doesn't form, 'all' this new ice is getting exported. 

After some 'predictable' date when a second ice bridge forms and stops the ice from being exported, there won't be enough time left in the winter to grow the ice to '2 meters' thickness.  The subsequent spring/summer thaw might start the ice export early.
Title: Re: The Nares Strait thread
Post by: Wipneus on December 31, 2014, 07:26:02 PM
And the Kane Basin imaged today. The same cracks as in the previous image are visible. Most of the Nares Strait has been cleared from the "old" ice floes. The piece that broke away from the Peterman door step has made a surprising distance.
Title: Re: The Nares Strait thread
Post by: Wipneus on January 01, 2015, 05:19:57 PM
Large pieces of the arch collapsing today.
Title: Re: The Nares Strait thread
Post by: Espen on January 01, 2015, 08:52:33 PM
As reported by Wipneus earlier, here is further evidence of the partly collapsed arch in the Lincoln Sea:
Title: Re: The Nares Strait thread
Post by: Neven on January 01, 2015, 10:47:38 PM
Pretty exciting. Thanks for all the images and animations, Wip and Esp.
Title: Re: The Nares Strait thread
Post by: A-Team on January 02, 2015, 11:23:10 AM
Starting to have more of the stable curvature of past years ...  compressive no tensile, parabolic, transferring thrust to immobile rock on the sides. Wait and see where it ends up though.

On the waters upstream of Nares Strait, Arctic Ocean, from 1991 to 2012
JM Jackson et al
free full: http://www.sciencedirect.com/science/article/pii/S0278434313003968 (http://www.sciencedirect.com/science/article/pii/S0278434313003968)

Quote
The Lincoln Sea is a bifurcation point where waters from the Canadian and Eurasian Basins flow to Nares or Fram Strait. Mechanisms that control which waters are found in the Lincoln Sea, and on its continental shelves, are unknown... Nares Strait is one of the two main passages through the CAA and year-round mooring data have estimated that the volume flux through Nares Strait ranges from 0.47 ± 0.05 million cu m per sec (Rabe in press) to 0.57 ± 0.09  (Münchow 2008), or roughly half of the total CAA transport (McGeehan 2012).
Title: Re: The Nares Strait thread
Post by: Wipneus on January 02, 2015, 04:32:42 PM
Not that stable, the collapsing continues...
Title: Re: The Nares Strait thread
Post by: Laurent on January 02, 2015, 04:43:22 PM
Is it an artefact ? Petermann seems to be activated at the front ? I did not notice that there is a canal that link Petermann and the south where hot water may come diretly.
Title: Re: The Nares Strait thread
Post by: Shared Humanity on January 02, 2015, 05:28:58 PM
Not that stable, the collapsing continues...

Hasn't a low set up over northern Greenland in the last few days? Could this be causing the breakup  of the arch? Most of the movement is occurring along the coast of Greenland as the ice moves  southwest.

Also, none of the ice that is now moving towards the strait appears substantial enough to block flow through the strait. I think all of this ice will be flushed through the strait.
Title: Re: The Nares Strait thread
Post by: Shared Humanity on January 02, 2015, 05:44:41 PM
I really don't like what I  am seeing with regards to ice thickness and  transport through Nares and the Fram.

http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticictn_nowcast_anim30d.gif (http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticictn_nowcast_anim30d.gif)

Title: Re: The Nares Strait thread
Post by: Wipneus on January 02, 2015, 05:57:12 PM
Winds (down the Strait) are strong, yesterday 40-60 km/h, today 25-45 km/h. According to http://earth.nullschool.net (http://earth.nullschool.net).
Title: Re: The Nares Strait thread
Post by: Wipneus on January 02, 2015, 06:46:14 PM
Several (3 in this case) quick-look images from different slices of the same orbit fit perfectly together for a panorama view.

(please click the image to see what I mean)
Title: Re: The Nares Strait thread
Post by: Espen on January 02, 2015, 07:04:18 PM
That is a great looking image Wipneus, where on the ESA site do find them, I can only locate images that are about 1 month old?
Title: Re: The Nares Strait thread
Post by: A-Team on January 02, 2015, 08:44:55 PM
I wish some of these gigabyte satellite sites would set up a dual file system -- orthogonal to their current ones -- so that it would be possible to just smart-download say all the quick looks like this without first having to dumb-download gigantic folders of stuff almost all of which the user does not want. Do they not have scripts or access to cheap cloud storage? It would bring a huge savings all around on server loads.

I re-processed Wip's beautiful tiling of Nares Strait (can this be extended around the whole perimeter of Greenland?) using 'value invert' in Gimp not to be confused with 'invert'. The first command treats the RGB as HSV and inverts the V (taking x to 255-x) without the user having to actually go through the steps of decomposition to HSV color space.

This is surprisingly effective -- click to view full size. This may amount to something physical in terms of mixing original polarizations like HH VH VV.  The lower image is 2x enlarged by cubic convolution, followed by modest wavelet sharpening. (I was looked to see if the Next Big Thing coming in cracking could be anticipated.)

If these quick looks are at lower resolution than the high resolution Sentinel grayscales, we might try the latter for panchromatic sharpening (replacing V) as Wip described for Landsat-8s. (As tiled, they are a bit rotated from  the grayscale Sentinels at http://ocean.dmi.dk/arctic/morrisjessup.uk.php (http://ocean.dmi.dk/arctic/morrisjessup.uk.php) -- that would knock down some of the benefit.)
Title: Re: The Nares Strait thread
Post by: Wipneus on January 03, 2015, 02:12:59 PM
That is a great looking image Wipneus, where on the ESA site do find them, I can only locate images that are about 1 month old?

Let me describe the typical way I get them.

First a Sentenial data set, product in ESA speak,  has an identifier and a name. Both uniquely identify the data, have you got one you can look up the other. In many cases you need them both.
The product name is something like S1A_EW_GRDM_1SDH_20150102T120132_20150102T120202_003992_004CEA_57D0
the corresponding product id
c71daeec-66d5-452e-a198-395a89c936fb

The product name is usually the base for file names used to store the product, it is an (insuficient) description as well.  The product id is just a UUID.

Lo-res, jpeg versions of the quicklook images can be seen in the sentinel data hub (https://scihub.esa.int/dhus/), graphical tool where you can do some selections, see some meta-data, see the quick-look image and request for the full (gigabyte) download.  Registration (free) is required.
Download of subsection of the data is planned 2015Q2, I think that may include the quicklook images.

Apart from the graphical tool there are programming interfaces (API's) to the data, the Open Data and Open Search. These are described here (https://scihub.esa.int/userguide/BatchScripting)

Open Data works with URL, understandable by your browser and by automatic tools (wget).
For instance with the name and id above, this will download the full (gigabyte) package data set:

https://scihub.esa.int/dhus/odata/v1/Products('c71daeec-66d5-452e-a198-395a89c936fb')/$value

Get the preview quicklook image:

https://scihub.esa.int/dhus/odata/v1/Products('c71daeec-66d5-452e-a198-395a89c936fb')/Nodes('S1A_EW_GRDM_1SDH_20150102T120132_20150102T120202_003992_004CEA_57D0.SAFE')/Nodes('preview')/Nodes('quick-look.png')/$value

Copy the string in the browser and download the image.

The scripts take care of creating these URI's, downloading the result and sometimes interpret the results.

So what I did in this case:

- used the data hub graphical tool to select the correct product. Get the product name (copied from the screen).
- start the odata-demo.sh script
  - use option 7: get id from product name
  - use option 11: get quick look image from id

This barely scratches what is possible. Downloading ALL quicklook images, given some selection parameters, is already routinely done here.
Title: Re: The Nares Strait thread
Post by: Espen on January 03, 2015, 07:06:59 PM
Thanks Wipneus for the instruction!

Further expansion of the arch area in Lincoln Sea:
Title: Re: The Nares Strait thread
Post by: Shared Humanity on January 03, 2015, 07:47:43 PM
Thanks Wipneus for the instruction!

Further expansion of the arch area in Lincoln Sea:

At what point do we stop calling it an arch and instead recognize it as a race to the exit?  ;)
Title: Re: The Nares Strait thread
Post by: Shared Humanity on January 03, 2015, 07:55:31 PM
I am amazed by the rubble of ice that appears in these images. Is this qualitatively different than in previous years or are we simply getting better at seeing the ice? Has there ever been a freeze season where the Nares transport simply did not shut own?
Title: Re: The Nares Strait thread
Post by: A-Team on January 03, 2015, 11:11:10 PM
Meanwhile down at Jakobshavn, which was supposed to be a featured location, we are not so thrilled with Sentinel. It malfunctions on about half the days and on the other half it needs to go another 100 km farther east. (Was there a miscommunication about why JI is being monitored, leading to centering on the fjord and Disko Bay?)

Like Nares, it seems JI is also anomalous for this date ... not fully frozen in by sea ice mélange. If so, this would reduce buttressing at the calving front and bump annual flux through the gate. Baffin Bay may be too warm these days.
Title: Re: The Nares Strait thread
Post by: Neven on January 03, 2015, 11:32:30 PM
At what point do we stop calling it an arch and instead recognize it as a race to the exit?  ;)

You mean, arch or march?  ;D
Title: Re: The Nares Strait thread
Post by: Rubikscube on January 04, 2015, 02:23:39 AM
Has there ever been a freeze season where the Nares transport simply did not shut own?

I recall that this is a topic which has previously been up for discussion in this thread, or at least somewhere on the forum, with the conclusion being that there has been a couple of winters in which proper arches have failed to establish. Can't remember the exact years, but I'm sure that others do.
Title: Re: The Nares Strait thread
Post by: Rubikscube on January 04, 2015, 03:07:45 AM
There you go SH. Hidden away in the "Home brew extent" thread was this most interesting link to Dr. Munchow's blog, which should answer your question.

http://icyseas.org/2012/06/19/nares-strait-ice-bridge-and-arctic-ice-thickness-change/ (http://icyseas.org/2012/06/19/nares-strait-ice-bridge-and-arctic-ice-thickness-change/)

To sum it up with the same quote that TerryM chose back then.
Quote
"I processed and archived maps of Nares Strait satellite images to guide 2003-2012 analyses of how air, water, and ice change from day to day. Ice arches formed as expected during the 2003/04, 2004/05, and 2005/06 winters lasting for about 180-230 days each year. In 2006/07 no ice arch formed, ice streamed freely southward all year, and this certainly contributed to the 2007 record low ice cover. In 2007/08 the arch was in place for only 65 days. In 2009/10, 2010/11, and now 2011/12 ice cover appear normal as the arches formed in December and lasted until July."
Title: Re: The Nares Strait thread
Post by: Shared Humanity on January 04, 2015, 05:10:55 AM
Thanks Rubikscube.
Title: Re: The Nares Strait thread
Post by: Espen on January 04, 2015, 09:05:48 PM
Further deterioration seen above Nares Strait / Lincoln Sea:
Title: Re: The Nares Strait thread
Post by: Espen on January 04, 2015, 10:31:25 PM
Another version between January 2nd and 4th:
Title: Re: The Nares Strait thread
Post by: A-Team on January 05, 2015, 06:09:45 PM
Less of an arch than a channel of weak ice that may be frozen onto rock on its periphery -- but enough to hold the center. Below is a Landsat8 quicklook of Nares from this fall at 120 m per pixel scale.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 06, 2015, 03:34:24 PM
A recognizable floe on January 4 (DMI’s Sentinel) is in the Lincoln Sea due east of Ellesmere Island’s Cape Union (slightly north of the eastern-most point (assuming the Sentinel view shows north straight up*)).  It has two collinear black streaks with a couple of white spots.

On January 5, this floe is in the Robeson Channel south of Ellesmere’s Cape Frederik VII.  It moved about 40 km in one day (if the Sentinel views are 24 hours apart).  This corresponds with “up to 40 km/day at the northern (actually NE) end of Nares Strait” I wrote on Dec 5 on this thread (from Kwok, 2005).

[* Notes:  I think the Sentinel views do not have north straight up; straight up is actually about NW.  Place names are according to map at https://mapsengine.google.com/map/viewer?mid=zbdKKg4fRHYo.kugA5VIgp5ec (https://mapsengine.google.com/map/viewer?mid=zbdKKg4fRHYo.kugA5VIgp5ec).]
Title: Re: The Nares Strait thread
Post by: Wipneus on January 06, 2015, 06:38:26 PM
For a full Nares "quick-look" panorama the path of the satellite must be at the right distance of the Strait. Happens every 2 or 3 days around noon (UTC), but then ESA decides not to provide all the possible data: the last two opportunities where lost. Today a full set, but not the best orbit position.

(click for a bigger image)

Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 06, 2015, 09:26:02 PM
Earlier I wrote: 
Quote
A recognizable floe on January 4 (DMI’s Sentinel) is in the Lincoln Sea due east of Ellesmere Island’s Cape Union. ...  It has two collinear black streaks with a couple of white spots.
On January 6 it has moved another ~40 km and can be found "due north" of the east edge of Petermann Glacier.  (By due north I mean straight up the image...)
Title: Re: The Nares Strait thread
Post by: Espen on January 07, 2015, 06:47:26 AM
The demolition team is having a break:
Title: Re: The Nares Strait thread
Post by: Wipneus on January 07, 2015, 07:34:09 AM
Meanwhile in the Kane Basin the ice is rushing south. The strong, up to 40 km/h winds, are causing a break-up of the fast ice in the Basin as well.

(click needed)
Title: Re: The Nares Strait thread
Post by: oren on January 07, 2015, 11:08:07 AM
I feel like wathcing a thriller... thanks for all the great images
Title: Re: The Nares Strait thread
Post by: Espen on January 08, 2015, 06:41:44 AM
Potentially more expansion:
Title: Re: The Nares Strait thread
Post by: viddaloo on January 08, 2015, 06:53:29 AM
Any info on real–estate prices by the Nares Strait, folks?

This is such a great thread, and I thank you all for posting your thrilling content here!  ;D
Title: Re: The Nares Strait thread
Post by: Wipneus on January 08, 2015, 07:25:21 AM
I choose for the Kennedy channel. Good luck with following the ice flows. The images are about 15 hours apart, the first (6th) from ascending orbital position the other descending. The different positions of the satellite cause all kinds of interesting distortions and change in lightning.
Title: Re: The Nares Strait thread
Post by: A-Team on January 08, 2015, 01:27:17 PM
Here is  07 Jan 17. There is a host of new cracks working their way out while expanding the present shape (actually it's getting a little lopsided to the northeast). That shape may reflect fracturing due to residual compressive stresses, along the lines of sandstone and granite exfoliation. Loose ice has seemingly plugged the Nares exit but without forming an arch -- hard to say what will happen next and what lesson it carries.

http://www.nature.com/news/sandstone-arches-form-under-their-own-stress-1.15590 (http://www.nature.com/news/sandstone-arches-form-under-their-own-stress-1.15590)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 08, 2015, 07:15:01 PM
'My' floe that "has two collinear black streaks with a couple of white spots" moved about 45 km in one day, and is straight up (pseudo-north) from Greenland's Cape Ulrich on the January 7 Sentinel image.  The collinear black streaks now parallel Kennedy Strait.  At this rate, the floe will get past Hans Island and to Franklin Island tomorrow. [Alert: I do not have successful prediction skills!  Watch the floe get stuck on Hans.]  (The floe is about 15 by 7 km is size, and the black streaks [becoming a single long streak?] are about 10 km long [combined] and 1/3 to 1 km wide.) [For scale reference, the narrow part of Petermann Fjord is about 14 km wide.]

An identifiable floe in Smith Sound on Jan. 7 image was about 60 km 'upstream' on Jan. 6.  A floe in Baffin Bay was 40 km upstream the previous day.  A large floe at the north end of Robeson Chanel was 20 km 'upstream' (within the Lincoln Sea) the previous day.  I don't see any evidence of floes plugging up anything within the flowing channel of Nares Strait and its up- and down-stream neighbors.  As there is a lot of chunky ice up there, of course something could get stuck any day.

Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 09, 2015, 06:49:41 PM
"My" flow went about 90 km between January 7 and 8 images!  On the Jan. 8 Sentinel image, it is between Greenland's Capes Jefferson & Madison and Ellesmere Island's Rawlings Bay (just above Kane Basin) [thus validating my disclaimer yesterday about my ability to predict things].

Elsewhere, floes appear to still be on the move as well.
Title: Re: The Nares Strait thread
Post by: Wipneus on January 10, 2015, 08:49:04 AM
Kane in the last few days. The previously fast ice that had been cracked into large chunks can be seen to have finally moved in the last frame. Winds up to 50 km/h keep blowing from the north of the Nares Strait.
Title: Re: The Nares Strait thread
Post by: A-Team on January 11, 2015, 12:41:58 PM
Here is some berg-tracking for 08-10 Jan 15. The top of the cracking is receding out of view of the Danmark Meterologiske Institut offerings at Lincoln into a region not picked up by Morris Jessup http://ocean.dmi.dk/arctic/morrisjessup.uk.php (http://ocean.dmi.dk/arctic/morrisjessup.uk.php)

The acceleration of ice is quite noticable as it nears the Strait. I'm thinking the blue shark will reach the narrows in six days or so.
Title: Re: The Nares Strait thread
Post by: Shared Humanity on January 11, 2015, 04:14:13 PM
Here is some berg-tracking for 08-10 Jan 15. The top of the cracking is receding out of view of the Danmark Meterologiske Institut offerings at Lincoln into a region not picked up by Morris Jessup http://ocean.dmi.dk/arctic/morrisjessup.uk.php (http://ocean.dmi.dk/arctic/morrisjessup.uk.php)

The acceleration of ice is quite noticable as it nears the Strait. I'm thinking the blue shark will reach the narrows in six days or so.

When the really heavy fracturing began to occur at the beginning of the month, my hope for a large floe of MYI plugging the strait went up. I think this is our last/best chance for having the Nares export shut down which would allow for ice formation to occur north of Greenland for the remainder of the freeze season.
Title: Re: The Nares Strait thread
Post by: Espen on January 11, 2015, 05:07:13 PM
Even MYI cant survive the Nares Mincer!
Title: Re: The Nares Strait thread
Post by: Shared Humanity on January 11, 2015, 05:19:17 PM
Even MYI cant survive the Nares Mincer!

If this is the case (I thought I recalled floes plugging things up in prior years?) than I think export will not stop this winter if the winds keep up.
Title: Re: The Nares Strait thread
Post by: Espen on January 11, 2015, 05:23:04 PM
MYI is not like it used to be?
Title: Re: The Nares Strait thread
Post by: Espen on January 11, 2015, 07:30:51 PM
Nice marble pattern, just waiting to enter the mincer?:
Title: Re: The Nares Strait thread
Post by: A-Team on January 11, 2015, 08:15:14 PM
So, like what happens when the growing Nares collapse structure meets the Arctic Ocean crack system? Guessing the orangish below -- that might drawn in some of the very oldest ice. (Have not checked which way Arctoc ice pack is moving, guessing east.)
Title: Re: The Nares Strait thread
Post by: viddaloo on January 11, 2015, 08:21:44 PM
It all goes down the drain? Very interesting question. Do we have any precedent from previous years?
Title: Re: The Nares Strait thread
Post by: Espen on January 11, 2015, 09:10:26 PM
So, like what happens when the growing Nares collapse structure meets the Arctic Ocean crack system? Guessing the orangish below -- that might drawn in some of the very oldest ice. (Have not checked which way Arctoc ice pack is moving, guessing east.)

A-Team, the thickest ice is above Ellesmere Island, though a bit more to the west than the "arch" is reaching now.
Title: Re: The Nares Strait thread
Post by: Espen on January 11, 2015, 09:12:42 PM
It all goes down the drain? Very interesting question. Do we have any precedent from previous years?

Hello Viddaloo, here is some news from Hardanger:

https://forum.arctic-sea-ice.net/index.php/topic,1041.msg43204.html#msg43204
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 12, 2015, 01:58:53 AM
'My' floe disappeared after the January 8 Sentinel image; it would have been nice to watch it go all the way to Baffin Bay.  I agree, Espen, many floes get chopped up near the start, or after hitting an island or cape.  I too thought A-team's blue shark was a shark.  Wouldn't 6 days take it into Baffin Bay, given that floes start going 5 to 20 km/day and end up going 50-90 km/day?
Title: Re: The Nares Strait thread
Post by: Wipneus on January 12, 2015, 08:29:12 AM
Winds have slowed to a slight breeze and come now from north-northwest direction. Currents will have to take care of the transport now and the large ice floats in Kane basing are pushed back.
Title: Re: The Nares Strait thread
Post by: viddaloo on January 12, 2015, 10:38:05 AM
Cracking up: Creating a channel from Fram to Nares?

PS: Espen, I have my own pet glacier in the Hardanger, though I have been to Folgefonna (sadly not Hardangerjökullen yet).
Title: Re: The Nares Strait thread
Post by: A-Team on January 12, 2015, 10:53:22 AM
Closer in, the area above the strait rotated slightly CW but also continued its export, whether due to residual wind or current.

Speaking of which, Andrew Muenchow has the observational data on tides, winds and currents summarized in excellent posts of 14 Sep 20 14, http://icyseas.org/tag/nares-strait/ (http://icyseas.org/tag/nares-strait/,) which includes a tidal harmonic analysis and 27 Jul 2012 (Allison Einolf) http://icyseas.org/2012/07/27/currents_winds_nares_strait_ice_arches/. (http://icyseas.org/2012/07/27/currents_winds_nares_strait_ice_arches/.)

Tidal darwin symbols, other than gam2, are explained at https://en.wikipedia.org/wiki/Theory_of_tides (https://en.wikipedia.org/wiki/Theory_of_tides)  'Evectional' terms arise from periodic gravitational effects of the sun on the moon. I'm not sure what is intended by 'red noise', probably Brownian noise (spectral density inversely proportional to 1/freq²) which is the baseline upon which tidal signal is imposed. (That is, tides are a complex superpositioning of many incompatible frequencies, best represented by Doodson's.)

Things are pretty quiet today at the Hans Island weather station, http://dalriada.sams.ac.uk/aws_hans/ (http://dalriada.sams.ac.uk/aws_hans/)

Quote
... ocean currents move water always to the south no matter if ice covers Nares Strait or not, no matter if the ice is moving or not, no matter which way the wind is blowing. The physical cause for this southward flow is that the sea level is always a few inches higher in the Arctic Ocean than it is in Baffin Bay... we measured this with tide gauges that we placed in protected coastal bays. We recovered 3 sensors; most rewarding was the recovery of one sensor in 2012 and 9 years of very good data.

The freeze-up of Nares Strait comes in one of three forms: 1. Ice stops moving in winter, because an ice barrier (ice arch or ice bridge) forms in the south that blocks all southward motion of ice; 2. only new and young ice moves southward, because an ice barrier forms in the north that blocks all entry of Arctic ice into Nares Strait; and 3. Arctic ice moves freely through Nares Strait, because no ice barriers are present. Our 2003-12 study period covers years for each of these different ice regimes.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 12, 2015, 03:07:12 PM
At the north end of Nares Strait, the shark’s mouth moved about 25 km between Sentinel 2015-01-10 and 2015-01-11.  (The shark (now red!), as shown in A-team’s animation, also rotated about 90 degrees counterclockwise – appropriately, it’s 'swimming' face forward!)  (A floe just south of the shark moved about 40 km – no rotation.)

At the north end of Baffin Bay, a round flow (~7 km diameter with a black comma shape in it) moved southward about 70 km between Sentinel 2015-01-10 and 2015-01-11.

Within Kane Basin, a floe (~5 km diameter with a black shallow S or integral sign across it) moved southward about 50 km between Sentinel 2015-01-10 and 2015-01-11.  On the 2015-01-11 image, it is just below the ‘no image’ part of the image.  This floe was opposite the south end of Petermann Fjord on 2015-01-08 where I can locate it; I think I see it in the 2015-01-06 image at the entrance to Nares Strait.  So this bit of ice will go from the Lincoln Sea to Baffin Bay in about 6 days.

I do not have a clue what is happening around Hans Island. 
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 13, 2015, 02:57:13 AM
With no 2015-01-12 Sentinel, I'm looking at DMI's NOAA AVHRR images for 2015-01-11  13:19 UTC ('yesterday') and 2015-01-12  13:09 UTC ('today'), you can see the shark moving southward, all but filling the strait.  The lozenge shaped floe south of the shark did rotate during this day and may well hit Hans Island broadside about tomorrow.  (This morning I thought it would just torpedo its way past [if the odd scatter on yesterday's Sentinel image around Hans Island was 'meaningless', as it appears to have been].)  Even if this lozenge rotates and slips by or breaks up on impact, the shark will do something (break up) or nothing (that is, block Nares Strait) on or about 2015-01-13.
[My prediction disclaimer stands: is there another possibility?]
DMI images available here:  http://ocean.dmi.dk/arctic/kennedy.uk.php (http://ocean.dmi.dk/arctic/kennedy.uk.php)

I'm awed by how big the cracking pattern is around the busted Lincoln Sea short-lived bridge (via the NOAA AVHRR images).  I realize that although the 2006-07 winter never had a Nares Strait blockage, I do not know how much Arctic sea ice was exported.  was there a Lincoln Sea arch/bridge or did it look something like what we can see today with 'constant' export of 'thick' ice?  (Anyone know?) [Per A-Team's post quoting Andrew Muenchow, is a 'northern arch' an arch within Nares Straight or does an arch in the Lincoln Sea count?]
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 13, 2015, 03:15:48 AM
Finally reading A-Team's link to Andrew Muenchow's bloghttp://icyseas.org/tag/nares-strait/ (http://icyseas.org/tag/nares-strait/), I have an answer to one of my questions:  a bridge in the Lincoln Sea counts as a Nares Strait bridge.  Therefore, I surmise, the 2006-07 winter had near constant 'thick' ice export through Nares Strait, and the effect on ice integrity in the Lincoln Sea and beyond was significant.

Another interesting excerpt from the above referenced blog:
Quote
Nares Strait ... is narrower than Fram Strait, but it transports as much fresh ocean water as does its wider sister facing Europe. Few people know this, including climate scientists who often model it with a bathymetry that is 10,000 years out of date from a time when Nares Strait did not yet exist.
Title: Re: The Nares Strait thread
Post by: Wipneus on January 13, 2015, 08:09:21 AM
I cannot find DMI-processed Sentinel images of Jan 12. Here is a "panorama" composed from the quick-look images.

(click to enlarge)
Title: Re: The Nares Strait thread
Post by: nukefix on January 13, 2015, 10:35:39 AM
I cannot find DMI-processed Sentinel images of Jan 12.
They are on scihub, ~400MB each so relatively small.
Title: Re: The Nares Strait thread
Post by: A-Team on January 13, 2015, 11:19:30 AM
Nice cloud-free AVHRR overview from 12 Jan 15 but try to do a time series. We are getting spoiled by cloud-penetrating radar?

 http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/201501121309.NOAA.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/201501121309.NOAA.jpg)
Title: Re: The Nares Strait thread
Post by: A-Team on January 13, 2015, 12:52:08 PM
Quote
Nares Strait ... is narrower than Fram Strait, but it transports as much fresh ocean water as does its wider sister facing Europe. Few people know this, including climate scientists who often model it with a bathymetry that is 10,000 years out of date from a time when Nares Strait did not yet exist.
I'm not sure what Muenchow is getting at here. 'Fresh' ocean water sounds like icebergs + ice meltwater, leaving overall total salt+fresh volume comparison to Fram up in the air. Probably clarified in his 2006 paper http://dx.doi (http://dx.doi). org/10.1175/JPO2962.1

Over longer times scales (Paleogene) of Nares formational history, geologist have been arguing bitterly about the tectonic history of Nares Strait for 80 years, right up to 2014, the two camps being Ellesmere-Greenland same plate vs 300 km of plate boundary transform fault (Wegener fault).

Paleo-bathymetry under these circumstances is really problematic. I don't doubt though that Nares flow has been an inconvenience to modellers that quickly got replaced by something from Daisy World. The issue is probably Nares is too shallow for Atlantic Water so the flow is mostly Pacific-derived today, but due to rebound from crustal unloading the sea level was ~120 m higher (Nares that much deeper) in the early Holocene.

Prior to Holocene onset, it sounds like Nares Strait was completely plugged up by convergence of the Innuitian, Greenlandic and Arctic ice sheets. Seafloor glacial gouges down by Disco Bay go much deeper than Nares (~220 m deep today at its shallowest sill).

Quote
The Holocene History of Nares Strait: 
Transition from Glacial Bay to Arctic-Atlantic Throughflow
Oceanography 24(3):26–41 2011
free full: http://www.tos.org/oceanography/archive/24-3_jennings.pdf (http://www.tos.org/oceanography/archive/24-3_jennings.pdf)

Retreat of glacier ice from Nares Strait and other straits in the Canadian Arctic Archipelago after the end of the last Ice Age initiated an important connection between the Arctic and the North Atlantic Oceans, allowing development of modern ocean circulation in Baffin Bay and the Labrador Sea.

As low-salinity, nutrient-rich Arctic Water began to enter Baffin Bay, it contributed to the Baffin and Labrador currents flowing southward. This enhanced freshwater inflow must have influenced the sea ice regime and likely is responsible for poor calcium carbonate preservation that characterizes the Baffin Island margin today.

 Sedimentologic and paleoceanographic data from radiocarbon-dated core HLY03-05GC, Hall Basin, northern Nares Strait, document the timing and paleoenvironments surrounding the retreat of waning ice sheets from Nares Strait and opening of this connection between the Arctic Ocean and Baffin Bay.

Hall Basin was deglaciated soon before 10,300 cal BP (calibrated years before present) and records ice-distal sedimentation in a glacial bay facing the Arctic Ocean until about 9,000 cal BP. Atlantic Water was present in Hall Basin during deglaciation, suggesting that it may have promoted ice retreat.

A transitional unit with high ice-rafted debris content records the opening of Nares Strait at approximately 9,000 cal BP. High productivity in Hall Basin between 9,000 and 6,000 cal BP reflects reduced sea ice cover and duration as well as throughflow of nutrient-rich Pacific Water.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 13, 2015, 05:12:31 PM
Per the DMI (http://ocean.dmi.dk/arctic/kennedy.uk.php (http://ocean.dmi.dk/arctic/kennedy.uk.php)) NOAA AVHRR 2015-01-13  06:23 UTC image, the lozenge that was tumbling counterclockwise, now, the end of it surely having bounced off of Joe Island (off the end of Petermann Fjord), will tumble faster.  And the shark is catching up.  Will they meet up (again, having been together in the Lincoln Sea) at Hans Island?
Title: Re: The Nares Strait thread
Post by: Laurent on January 13, 2015, 06:33:25 PM
I think there is some move also in one of the channels between bank island and Ellesmere. What data set do you use when using http://earthexplorer.usgs.gov/ (http://earthexplorer.usgs.gov/) ?

Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 13, 2015, 07:58:36 PM
The shark is kissing the fast ice off of Petermann Fjord (or is that a bit of ice it's thinking of eating? - see today's partial Sentinel image) - I didn't expect the shark to start spinning.  It, too, may bounce off of Joe Island or upstream fast ice.  The shark (its mouth, specifically) has moved 70 km in two days.

The lozenge sure slowed down.  Yesterday I thought it would reach Hans Island today.  Maybe tomorrow.
Title: Re: The Nares Strait thread
Post by: Andreas Muenchow on January 14, 2015, 12:09:00 AM
Quote
Nares Strait ... is narrower than Fram Strait, but it transports as much fresh ocean water as does its wider sister facing Europe. Few people know this, including climate scientists who often model it with a bathymetry that is 10,000 years out of date from a time when Nares Strait did not yet exist.
I'm not sure what Muenchow is getting at here. 'Fresh' ocean water sounds like icebergs + ice meltwater, leaving overall total salt+fresh volume comparison to Fram up in the air. Probably clarified in his 2006 paper http://dx.doi (http://dx.doi). org/10.1175/JPO2962.1

Sorry for the sloppy language there ... I meant the amount of liquid freshwater relative to "ambient water" that has a salinity of 34.8 (think of this as grams of salt in a kg of seawater). So if you observe a salinity of 33.8, it has some freshwater in it that diluted the original water that has 34.8. So, melted ice, rivers, rain, melted snow all make water fresh. There is also (solid, frozen) freshwater in ice and icebergs.

What matters for climate is the amount of vertical density (=salinity; temperature has little impact on density in Arctic waters) stratification in the downstream northern North-Atlantic . This determines how much "new" deep water forms at the surface that then sinks to great depth (2000-m or so) and that then circulates around the globe slowly mixing and rising until it gets back to the surface, maybe, a 1000 years later, somewhere in the North Pacific. So, freshwater flux is what modelers want from me as a metric to include in and/or check their models against. In Fram Strait exports its freshwater mostly as ice while Nares Strait exports freshwater mostly as water.

My little quib about the bathymetry of climate models being 10,000 years out of date, well, I was poking fun of the majority of models that do not have a Nares Strait and in these models all Arctic-to-Atlantic exchanges happens via Fram Strait. There are several arguments why this is not a great idea that relate to the scales of motion of an ocean that is vertically stratified. In a nutshell, such fluids have lots of structure and energetic motions at 5-10 km horizontal scales. That's why, in Nares Strait, you can often see (in the absence of winds) flows to south along Ellesmere and no flow or flow to the north along Greenland. Notice in many radar images that the ice on each side of Nares Strait has a distinctly different appearance that relates to its surface roughness. Different physics, different currents, different ice, different shades of gray.

Physics is fun ... and thank you all for exposing so much great stuff here ... and I feel strongly encouraged by the new Sentinel imagery that you posted here ;-)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 14, 2015, 03:46:47 PM
Per the DMI (http://ocean.dmi.dk/arctic/kennedy.uk.php (http://ocean.dmi.dk/arctic/kennedy.uk.php)) NOAA AVHRR 2015-01-14  06:12 UTC image (and the 01-13  06:23 image), the lozenge has almost reached Hans Island (moving about 55 km in 24 hours even after having seriously slowed down yesterday at Joe Island).  Will it stop?  Will it get stuck?  Will it shatter?  (Yesterday I predicted it would continue spinning after hitting Joe Island.  It appears to not be spinning.)

The shark remains off the mouth of Petermann Fjord.  I certainly didn't expect it to get stuck there!  (love or hunger?, if I was to anthropomorphize the animalized ice floe)  It moved maybe 10 kilometers in 24 hours, but mostly across the strait, not down the strait. There may be ice debris (mélange) piling up behind the shark.

Not much movement of ice in the Lincoln Sea in 24 hours, per the AVHRR images.  The floe closest to the Greenland side of the mouth of Robeson Channel moved the most (maybe 5 km).

On the east side of the Lincoln Sea (north of Greenland), a large crack has extended/widened north from Cape Morris Jesup in the past 24 hours.
Title: Re: The Nares Strait thread
Post by: viddaloo on January 14, 2015, 04:31:06 PM
Am I reading it wrong, or is the average flow through Nares and Kennedy about 3 times bigger than that of the Amazon?
Title: Re: The Nares Strait thread
Post by: Andreas Muenchow on January 14, 2015, 05:38:42 PM
Am I reading it wrong, or is the average flow through Nares and Kennedy about 3 times bigger than that of the Amazon?
It depends what you mean by average flow. If you want to know how much volume flows southward through Nares Strait, that number is about 10 times that of the Amazon River. If you want to know how much freshwater (zero salinity) flows through Nares Strait (relative to ocean water that has 34.8 grams per kilograms), then Nares Strait transports about half as much freshwater to the south as does the Amazon River. This is all just counting the ocean, not ice. That's extra for Nares Strait, but zero for the Amazon.

It is very hard to measure freshwater flux, because one needs multiple ocean current measurements across as section and with depth along with multiple salinity measurements, because both currents and salinity change by a rather large amount in the time averages both with depth and across from Greenland to Ellesmere Island.

The action in physics is not always where you see its results.
Title: Re: The Nares Strait thread
Post by: viddaloo on January 14, 2015, 06:39:06 PM
If you want to know how much volume flows southward through Nares Strait, that number is about 10 times that of the Amazon River. If you want to know how much freshwater (zero salinity) flows through Nares Strait (relative to ocean water that has 34.8 grams per kilograms), then Nares Strait transports about half as much freshwater to the south as does the Amazon River. This is all just counting the ocean, not ice. That's extra for Nares Strait, but zero for the Amazon.

Thanks, Andreas. I'm pretty amazed by this fact. Although not technically a river, the Nares Strait is to my knowledge one–directional (it doesn't change during the day or during the year), unlike Saltstraumen or other tidal flows, so with the narrow river–like topography of the Nares, it would not surprise me if this was the greatest 'river' in terms of sverdrups in the world. (Obviously not counting the Gulf Stream, that in no way has narrow, river–like topography.)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 14, 2015, 08:25:24 PM
Today's DMI Sentinel image is out.  The lozenge is floating past Hans Island and the shark remains stuck on Joe Island, although a piece of its' head' broke off which is floating downstream. The shark, with a small floe, now form a bridge across most of Nares Strait. (Fast ice off of Petermann Fjord prevents anything floating between Joe Island and Greenland.) Will this close the strait for the season? Or will something break?  Time will tell.  Ice is definitely backing up behind this bridge. 
Title: Re: The Nares Strait thread
Post by: solartim27 on January 15, 2015, 11:08:38 PM
Sentinel was blacked out for Nares,

http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150115s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150115s01a.ASAR.jpg)

but Modis (?) shows the shark shattered to bits

http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/201501151234.NOAA.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/201501151234.NOAA.jpg)

Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 16, 2015, 01:52:32 AM
Poor shark; it was fun watching you while you lasted.

Thanks, solartim27 for posting.  Jury duty kept me busy all day today (and will again tomorrow).
Title: Re: The Nares Strait thread
Post by: viddaloo on January 16, 2015, 12:34:01 PM
Can someone explain this image for me? What do we see in this picture?

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKennedy%2F201501151234.NOAA.jpg&hash=50bff4d898fc3d251665aeb338c17a15)

(NOAA Jan15 12.34 UTC)
Title: Re: The Nares Strait thread
Post by: Laurent on January 16, 2015, 12:49:33 PM
We see the Lincoln sea viddaloo being smashed and sent through Nares strait. For the black part It may be a cloud or an artifact.
https://en.wikipedia.org/wiki/Lincoln_Sea
Title: Re: The Nares Strait thread
Post by: solartim27 on January 16, 2015, 06:18:53 PM
viddaloo, this may be more basic than you want, but it's northwestern Greenland on the bottom, with the Nares Straight running to the bottom left corner.  It is labeled on the sat map image section as Kennedy on this link (map is 1/2 way down page on left):
http://ocean.dmi.dk/arctic/kennedy.uk.php (http://ocean.dmi.dk/arctic/kennedy.uk.php)

The remains of the shark are stationary in front of Peterman, with a large flow approaching.  Will it break through, or maybe get the arch started?
http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/201501160731.NOAA.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/201501160731.NOAA.jpg)
Title: Re: The Nares Strait thread
Post by: viddaloo on January 16, 2015, 06:29:19 PM
viddaloo, this may be more basic than you want, but it's northwestern Greenland on the bottom, with the Nares Straight running to the bottom left corner.

Solar, what confuses me is you have the color black in 3 main places:

1) The Nares Strait itself.
2) The big black blob in the upper right.
3) Inland Greenland and near the shore.

Am I right to believe that 1) and 3) is new/thin ice (not open water), and that 2) is some sort of cloud or fog causing an image error?
Title: Re: The Nares Strait thread
Post by: Andreas Muenchow on January 16, 2015, 07:21:35 PM
Quote from: viddaloo

Solar, what confuses me is you have the color black in 3 main places:

1) The Nares Strait itself.
2) The big black blob in the upper right.
3) Inland Greenland and near the shore.

Am I right to believe that 1) and 3) is new/thin ice (not open water), and that 2) is some sort of cloud or fog causing an image error?
1. Thin ice;
2. Clouds;
3. Don't know (inland) and thin ice (near the shore).

It is a thermal image that shows the amount of "heat" received by the satellite sensor. The ocean is "hot" at its freezing point of -1.7 C while the surface of thick ice is as cold as the air above it. If the air is very clear (few particles), then there is nothing that can radiate heat, however, clouds to radiate heat and their temperature depends on where the cloud is and what type of particles do the "oscillations" that radiates off at the (infra-red) frequency that the satellite senses ... or so I think.
Title: Re: The Nares Strait thread
Post by: A-Team on January 16, 2015, 07:58:47 PM
Black smokers ... we saw a lot of those clouds last year sweeping across the central Arctic Ocean. Not recalling whether they were ice fog, low clouds, thick clouds, warm clouds, or what. They are quite different in appearance from wispy clouds (which cast shadows on the ice).

Quite a bit of movement in today's Sentinel.
Title: Re: The Nares Strait thread
Post by: jdallen on January 17, 2015, 02:29:23 AM
Black smokers ... we saw a lot of those clouds last year sweeping across the central Arctic Ocean. Not recalling whether they were ice fog, low clouds, thick clouds, warm clouds, or what. They are quite different in appearance from wispy clouds (which cast shadows on the ice).

Quite a bit of movement in today's Sentinel.
The ice really does not seem strong enough to resist being ground up at the approach to the strait. I'm pessimistic about an arch forming.  The strait remaining open may weaken Baffin ice, it seems.  Amateur perspective here for sure.
Title: Re: The Nares Strait thread
Post by: viddaloo on January 17, 2015, 02:45:21 AM
My own amateur perspective was expanded when learning in this thread that the flow in this strait is 10 times the flow of the Amazon River. No wonder it flows even in winter with that kind of proportions.

(Still trying to find the viking or norse name for this strait, as vikings traded with inuits all the way up to Ruin Island inside the strait.)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 17, 2015, 04:29:54 AM
Comparing the January 14 with the January 16 Sentinel images of "Kennedy" shows an odd shaped floe going about 75 km (~35 km/day) from the mouth of Robeson Channel to Ellesmere's Lady Franklin Bay (opposite Petermann Fjord).  (Another identifiable floe moved a similar 75 km and just past Petermann Fjord.)  Therefore, I suspect the pieces of the shark are now at least to Hans and Franklin Islands.

Title: Re: The Nares Strait thread
Post by: nukefix on January 17, 2015, 02:09:51 PM
How thick is that ice that is currently flowing out through Nares?
Title: Re: The Nares Strait thread
Post by: A-Team on January 17, 2015, 03:33:10 PM
Quote
How thick is that ice that is currently flowing out through Nares?
It depends very much on the year and arch/not; no real bottom line to take away. The results from upward looking sonar are described here at quite an interesting level of detail: http://icyseas.org/2012/08/ (http://icyseas.org/2012/08/). I didn't see annual total ice volume nor an origin map of the Arctic ocean.
Title: Re: The Nares Strait thread
Post by: solartim27 on January 18, 2015, 04:38:19 AM
Has there been a wind shift?  Flow direction has reversed at the entrance to Nares.  Main channel has not had any good coverage for a while.  (Sorry, I don't know how to do the fancy link with the changing images)

http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150117s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150117s01a.ASAR.jpg)

http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150116s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150116s01a.ASAR.jpg)

Title: Re: The Nares Strait thread
Post by: Wipneus on January 18, 2015, 09:29:03 AM
Yes, according to earth.nullschool.net winds are now blow in the direction of the Strait from the south, reaching 25 km/h in the northern part.

Here is Lincoln, nothing yet from more south.
Title: Re: The Nares Strait thread
Post by: A-Team on January 18, 2015, 02:33:06 PM
Here is a speculative interpretation of competing forces acting on the ice in Lincoln Sea. The purple arrows represent the 'inward' collapse of the Nares arch that we've been following. The yellow arrows show Arctic Ocean ice being pulled apart (slightly) towards the Fram Strait in a cracking pattern we have seen develop many times but not necessarily come to full development. The red arrows are where the Arctic Ocean forces are 'taking over' from the Nares sphere of influence. If this plays out, the purple region will get taken up in the Fram-ward motion.

The wind at Nares is from the north again and currently opposes the above scenario in the Fram as well.
Title: Re: The Nares Strait thread
Post by: solartim27 on January 18, 2015, 07:50:17 PM
Sentinel gives a nice shot today, no major changes, ice is flowing, but not as fast.

Today: 
http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150118s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150118s01a.ASAR.jpg)

2 days ago:
http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150116s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150116s01a.ASAR.jpg)
Title: Re: The Nares Strait thread
Post by: Shared Humanity on January 18, 2015, 10:46:03 PM
Wouldn't this continued flow, although slower, be driven by water currents in the strait and the slower speed is because strong winds are not aiding the flow?
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 19, 2015, 01:58:12 AM
The two floes I identified as having gone about 75 km in two days on January 16 (i.e., from 14th to 16th) have moved an additional **drum roll** only 15 or 20 km in the subsequent two days (16th to 18th)!

With movement this slow, I imagine a bridge could fairly easily form.
Title: Re: The Nares Strait thread
Post by: solartim27 on January 19, 2015, 07:32:55 AM
Tor will be happy to hear there is a good sized chunk of the shark transitioning to the Kane area on DMI, not broken up, just not covered when I first looked at Sentinel. 

I was looking around the DMI page and found lots of motion developing over towards Fram, as A-Team showed above.  The Nord station gives a pretty good overview.

http://ocean.dmi.dk/arctic/nord.uk.php (http://ocean.dmi.dk/arctic/nord.uk.php)

1/18: http://ocean.dmi.dk/arctic/images/MODIS/Nord/20150118s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Nord/20150118s01a.ASAR.jpg)

1/16: http://ocean.dmi.dk/arctic/images/MODIS/Nord/20150116s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Nord/20150116s01a.ASAR.jpg)

1/15: http://ocean.dmi.dk/arctic/images/MODIS/Nord/20150115s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Nord/20150115s01a.ASAR.jpg)

Similar motion can be seen at the pages labeled Dove further south on the east coast.

Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 19, 2015, 05:01:36 PM
Happy me!  I'm realizing that this ice shark didn't die, but multiplied (broke into pieces) and is going south to its/their happy hunting ground (melt & sublimate).
Title: Re: The Nares Strait thread
Post by: johnm33 on January 20, 2015, 01:21:52 AM
SH Looking at A-Teams scene and description above, in my imagination [if nowhere else] the deep circumpolar drift spins upwards just south of the red arrows, [ it carries excess inertia/speed from being further south and the rotational/orbital energy implicit in that, plus it's a lot closer to the axis of rotation and suffers from a deficit of spin] so apart from breaking up/through the Pacific water above it, it seems to be overturning anti-clockwise as it surfaces and heads for Nares[and all points south] the yellow arrows indicate the ongoing process as the water of this current tries to relieve it's stress whilst heading for Fram. One of the consequences is that the water heats a little, but bear in mind this is deeper warmer more saline water  and again if nowhere else but in my imagination [in this shot] you can see the black smoker clouds emanating from the central part of the broken ice that's heading for Nares being blown north [this area of water is energetically fraught and much more likely to evaporate]. I also suspect that the reason the ice is breaking up so easily whilst maintaining it's shape is that last winter there was a lot of snow falling on to barely frozen ocean creating a lightweight sea ice of fairly normal thickness which implies easier melt and more sail. [ and prospects for a far too interesting year].
Title: Re: The Nares Strait thread
Post by: solartim27 on January 20, 2015, 02:43:36 AM
Still plenty of motion, some big stuff is approaching from Lincoln.

Today: http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150119s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150119s01a.ASAR.jpg)

Yesterday: http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150118s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150118s01a.ASAR.jpg)

Lincoln: http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/20150119s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/20150119s01a.ASAR.jpg)

DMI pages:  http://ocean.dmi.dk/arctic/kennedy.uk.php (http://ocean.dmi.dk/arctic/kennedy.uk.php)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 20, 2015, 03:09:07 PM
Yup:
Between Sentinel 18th and 19th images, ice moved about 6 km in the Lincoln Sea, 22 km in the Robeson Channel, 28 km off of Petermann Fjord, 29 km near Hans Island, 40 km at north end of Kane Basin (largest piece of shark), 22 km in mid-Kane Basin and 20 km at the south end of Kane Basin.
Title: Re: The Nares Strait thread
Post by: viddaloo on January 21, 2015, 08:38:33 PM
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fwww.xearththeory.com%2Fimages%2Fplanetselectricalcircuits%2Fbarents-gyre-beaufort-labrador-current-circuits.jpg&hash=611f1a0ffbcb2e0c73e0f6a8ab62b82a)

More Nares Strait 'Fun Facts': I recently watched a docu on the lower Amazon River, and noticed that the narrator told me you couldn't see land if you were on a ferry in the middle of it. While the topography is different, to say the least, with Nares at 3 times the width of the lower Amazon at the narrowest part of the Strait, for all I know it may just be possible to be in the center of it and not see land on either side.

Also, as we remember, the stream or throughput in the mostly one–directional Nares current is 5–10 times that of the Amazon River.
Title: Re: The Nares Strait thread
Post by: Wipneus on January 22, 2015, 10:02:31 AM
In a sequence of two DMI Sentinel-1A images, ice can be seen racing down a narrow channel. At the same time some ice in the wider basin goes in opposite direction. Maybe you can appreciate the "gyre" from the attached Uni Hamburg ASMR2 derived sea ice concentration animation.

(ATM these images are not in the public Sentinel archive (yet), DMI appears to able to acquire Sentinel-1A data from a better source.)

(the Sentinel picture needs a click to start animating)
Title: Re: The Nares Strait thread
Post by: viddaloo on January 22, 2015, 01:14:00 PM
Bridge forming?

The ice transport seems to have stopped today. Is this just temporary, or for the season?

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FLincoln%2F201501220443.NOAA.jpg&hash=727c24b6c10971b30c56f6a082dd24b9)

Edit: Transport seems to have started again in the course of just 101 minutes.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FLincoln%2F201501220624.NOAA.jpg&hash=a362283477191f103d9759588e6268d0)

Edit2: The strait looks pretty empty (black). A consequence of ice transport having stopped for a number of hours, or days?
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 22, 2015, 02:19:30 PM
Between January 19 and January 21 Sentinel images (http://ocean.dmi.dk/arctic/lincoln.uk.php (http://ocean.dmi.dk/arctic/lincoln.uk.php)), individual ice floes have moved southward as follows:
100 km from Nares Strait in the Lincoln Sea (on western side) - 2 km in two days.
Lincoln Sea closer to Nares Strait - 17 and 22 km in two days (more movement closer to Nares).
Lincoln Sea to Robeson Channel - 34 km in two days.
within Robeson Channel - 60 km in two days.
between Petermann Fjord and Franklin Island - 65 km in two days.
within Kane Basin (north) - 60 km in two days (shark remnant)
within Kane Basin (south) - 42 km in two days.
Baffin Bay (north) - 30 km in two days
Baffin Bay (further south) - 10 km in two days (my old floe with an integral sign on it)

I cannot say what is happening today, but ice was on the move between 3 days ago and yesterday.
[place names from https://www.google.com/maps/d/view?mid=zbdKKg4fRHYo.kjkUmepfXc9A (https://www.google.com/maps/d/view?mid=zbdKKg4fRHYo.kjkUmepfXc9A)]

Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 22, 2015, 02:50:02 PM
Between January 21 and 22 NOAA AVHRR images, there is clear movement of ice in the Lincoln Sea toward Nares Strait. 

Look at the Sentinel images for a clearer look at floes (and mélange and thin ice) within Nares Strait.  Even then, some details may be deceptive.  I've learned a lot by comparing two images a day apart, seeing what moves and what doesn't, and what 'just changes'.  Some floes have markings that are recognizable for a long time, and some markings 'disappear'.
Title: Re: The Nares Strait thread
Post by: Sonia on January 22, 2015, 05:38:19 PM
Is this an iceberg?  I've been watching this thing for a couple of months now.  I think it came down from the north around the end of October and may have been sitting on the Petermann sill much of the time since.  Today's Sentinal image shows it merging into traffic so it may be interesting to watch it travel down the Nares.
Title: Re: The Nares Strait thread
Post by: Wipneus on January 22, 2015, 06:40:19 PM
Here is a detail (in 10m/pix resolution) of the iceberg. Image from Jan 17, when still on the Petermann doorstep. No other hi-res data I could find. It could be a double ice floe with some heavy deformed crests in between.
(needs a click of course)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 22, 2015, 06:43:27 PM
Sonia (good eyes!), it is either an iceberg or a floe (about 3 km 'square-ish') - I cannot tell the difference.  I see it on January 4 just off of Petermann Fjord (Hall Basin), then drifting about 25 km northwestward, then - in the past two days - getting caught in the current, as you note.  It will be fun watching. [grammar edit]
Title: Re: The Nares Strait thread
Post by: Wipneus on January 23, 2015, 07:55:22 AM
Attached a 40m/pix detail of Sonia's floe or iceberg located in the main stream just outside the Petermann fjord (direction top of this image), data from 2015-01-21. As can be seen the white is part of a bigger and darker floe.
In the animation the floe is on the move to the south.

(click to animate)
Title: Re: The Nares Strait thread
Post by: viddaloo on January 23, 2015, 07:14:46 PM
The two fracture zones are getting really close to each other now. What happens if/when they connect?

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FLincoln%2F201501230613.NOAA.jpg&hash=b87822ba7249bb5b2d2b88598e00f13f)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 23, 2015, 08:41:03 PM
Coincidental (?) with the interacting Lincoln Sea fracturing and Fram Strait-related fracturing, a 'huge' piece of Arctic ice has moved southward towards the Lincoln Sea about 20 km (I'm not sure in how many days because of clouds or fuzzy images prior to the "NOAA AVHRR 2015-01-23  12:46" image similar to the one attached above by viddaloo).  You can see the thin (black) eye-shaped openings where the transverse fault has kinks (especially one about 150 km north of Nares Strait - what I'm calling a fault is the crack in the ice that goes almost straight and is nearly perpendicular to Nares Strait).  A curvy crack (more-or-less perpendicular to this fault) that opened up a couple/few km yesterday has mostly closed, but 'all' the ice has moved toward Nares Strait.

(For scale, Petermann Glacier is about 14 km wide at its narrowest.)
Title: Re: The Nares Strait thread
Post by: A-Team on January 23, 2015, 09:47:48 PM
Quote
The two fracture zones are getting really close to each other now. What happens if/when they connect?
It looks like the Lincoln fracture zone is going to over-write Nare's. However as Andreas M has shown, Arctic water will still flow out Nares because the Arctic Ocean is 6-8" higher than Baffin Bay (after adjusting for tidal variance). I guess this means the bergs will still go out the strait -- ice in the Lincoln sea may be cracking Fram-wards but we're seeing very little bulk transport out of Lincoln, only more cracking.

Quote
Coincidental (?) with Lincoln Sea and Fram Strait-related fracturing, a 'huge' piece of Arctic ice has moved southward about 20 km towards the Lincoln Sea.
Interesting. Can you post a screenshot or two? I am not picturing how this would work as incompressible ice is already filling Lincoln.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 23, 2015, 10:17:48 PM
A-Team: Did you mean "Lincoln fracture zone is going to over-write Fram's"?

On your flashing images, my "huge piece of ice" is bounded on the left by the fault/crack that is perpendicular to Nares Strait and on the right by the Fram Strait complex of cracks.  It is roughly 200 to 250 km wide.  This block of ice is re-filling the Lincoln Sea more slowly than the Lincoln Sea is losing ice to Nares. 

Not only are 5 to 20 km hunks of ice breaking off the Arctic ice mass and moving toward and into Nares Strait, but this large piece of the Arctic ice mass has also moved toward Nares Strait.  (Changing winds and currents might stop this movement, but the recent movement is clear from analyzing the "eye shaped" openings in the fault, and (separately) measuring the decreasing distances of "known points" (crack locations) on the "huge piece of ice" with the Greenland shore.)

Did this help?

Title: Re: The Nares Strait thread
Post by: viddaloo on January 23, 2015, 10:25:24 PM
It looks like the Lincoln fracture zone is going to over-write Nare's.

Funny, I don't get what either of you try to say! But at least I share in A–Team's confusion about what Tor is on about!  ;D (Edit: And in Tor's about A–Team.)

As usual, nothing personal, I just like to know what you mean.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 24, 2015, 12:27:55 AM
Thanks for letting me know.  I'll try to figure out another way to share what I'm seeing (but it won't be today).
Title: Re: The Nares Strait thread
Post by: viddaloo on January 24, 2015, 01:36:04 PM
Fram fracture zone expanding westward 21–23 January.
Title: Re: The Nares Strait thread
Post by: A-Team on January 24, 2015, 03:07:08 PM
Nice broken glass effect!

Below is the 24th. The area of pending 'takeover' is a bit awkwardly located for Sentinel so let's hope for cloud-free
Title: Re: The Nares Strait thread
Post by: viddaloo on January 24, 2015, 07:37:43 PM
Thx.

Fram fracture zone expanding westward 22–24 January (and some fun).
Title: Re: The Nares Strait thread
Post by: viddaloo on January 24, 2015, 09:24:12 PM
(Am I the only one who sees a guy with sunglasses going down the drain?)
Title: Re: The Nares Strait thread
Post by: be cause on January 24, 2015, 10:06:07 PM
.. and I've never imagined I would see the Arctic pouring into the Atlantic so dramatically .Sunglasses or not , is what's happening in Lincoln Sea exceptional or should my awe be directed elsewhere :)
Title: Re: The Nares Strait thread
Post by: MikeAinOz on January 24, 2015, 10:57:11 PM
I also have been watching, bc, and I think this is exceptional. I was trying to figure out if the Nares Strait arches were going to form and block the strait, and when they normally do form when I came across this: http://www.nasa.gov/topics/earth/features/earth20100218.html (http://www.nasa.gov/topics/earth/features/earth20100218.html) regarding the arches and what happened in 2007. There are other awesome things happening in the Arctic, particularly in Greenland, but this gets my upvote for awesomeness   :).
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 25, 2015, 06:41:21 AM
I have compared Sentinel images of the Lincoln Sea dated 01-22 and 01-24.  All distance moved are over this two day period.

A large floe in the middle of Lincoln Sea went about 7 km.  A large floe almost to Nares Strait (on 01-24) went about 20 km.  Floes closer to or in Nares went further (45 km or more). 

Looking at ice floes in the upper left part of the images that, although with identifiable boundaries, are in close contact with their pre-separated neighbors, and ice that looks to be part of the Arctic ice sheet (no clear floe boundaries, at the top left of the image) I see ice moving 9 to 12 km toward Nares Strait.  (Some cracks open wider, and others close up.)

From this data, I conclude that not only is ice breaking off the Arctic ice sheet in the Lincoln Sea and heading for the Nares Strait, but that a section of the Arctic ice sheet is also moving toward the Lincoln Sea. 

Looking at ice in the upper center and upper right of these Sentinel images, the ice is moving very little; in some places it is moving a tiny bit toward Fram Strait. 

Comparing NOAA  AVHRR images (2015-01-19  13:30 and 2015-01-23  12:46 - among the best recent images available) that show a much larger part of the Arctic (over 400 km north of Nares Strait), note the major crack that goes from the Ellesmere coast near Nares Straight almost straight up the images.  I can identify marks on the ice to the left of this major crack (e.g., one about 270 km from Nares) that don’t move between these two images, whereas marks to the right of this crack (e.g., one also about 270 km from Nares) show about 7 km movement toward Nares. (A mark about 400 km north of Nares moved about 10 km, but as it is to the right of a Fram-related crack, its motion is toward a point on Greenland some 200 km east of Nares.)  This data supports my conclusion (above) that a section of the Arctic ice sheet is moving toward Lincoln Sea, although this movement may be more related to what I have called Fram Strait related cracking and that the movement toward Nares may be coincidental.

With my geological education, I call a crack that has transverse movement (like the San Andres fault) a fault.  Natural ice is a mineral, so the ice sheet and floes, etc. are monomineralic rocks.  I consider the major cracks identified in the previous paragraph which have transverse movement to be faults.

All of these images are available from http://ocean.dmi.dk/arctic/kane.uk.php (http://ocean.dmi.dk/arctic/kane.uk.php).  [All of these distances are very approximate, given, among other things, the poor quality of the wooden ruler I’m using.]

Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 25, 2015, 06:59:37 AM
Besides the no-ice-bridge in 2006-7, only a short-lived bridge formed in 2007-8 (lasted 65 days, starting, I think, in March).  All it will take is for one sturdy floe to get stuck.  The 'shark' got stuck for a day or so, but then shattered.
Title: Re: The Nares Strait thread
Post by: Wipneus on January 25, 2015, 09:41:53 AM
Sonia's ice floe/berg seems to have raced to Franklin island. I could be wrong, but there is no data in the public Sentinel archive of this area after Jan 22.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 25, 2015, 03:38:42 PM
Yes, Sonia's floe/berg moved 90 km in two days.  A recognizable floe behind it went 75 km and one ahead of it went only 65 km.  As Sonia's iceberg(?) is going faster than nearby floes, I think it might be an iceberg that is more strongly affected by Nares current. (The wind at two points on/near Nares Strait is a crosswind, per http://stratus.ssec.wisc.edu/products/rtpolarwinds/ (http://stratus.ssec.wisc.edu/products/rtpolarwinds/), so the iceberg's speed is unlikely associated with wind.)
Title: Re: The Nares Strait thread
Post by: Sonia on January 25, 2015, 06:34:18 PM
Interesting wind links, Tor, I didn't know those.  But if the wind is determined from cloud tracking, I would expect it may or may not correspond well to surface wind.  I kind of like http://dalriada.sams.ac.uk/aws_hans/ (http://dalriada.sams.ac.uk/aws_hans/) as a surface data point on the Nares.

Incidentally, the weather station is currently reporting that the wind has recently dropped.  So I'll be watching the Kane for arch formation.  From the latest Sentinal images, the channel of briskly moving ice has been narrowing and other ice in the Kane, while not completely stationary, has looked sluggish.  I can imagine that these conditions -- sluggish ice and light winds -- might be conducive to freeze up.
Title: Re: The Nares Strait thread
Post by: A-Team on January 25, 2015, 10:54:42 PM
This has some potential for visual comparison of different multiple dates ... but I wouldn't say that potential was realized yet ...
Title: Re: The Nares Strait thread
Post by: viddaloo on January 26, 2015, 09:50:35 AM
Check out this (http://cci-reanalyzer.org/DailySummary/) 20C anomaly 'heatwave' over Fram:

Title: Re: The Nares Strait thread
Post by: Jim Hunt on January 26, 2015, 10:13:31 AM
Check out this (http://cci-reanalyzer.org/DailySummary/) 20C anomaly 'heatwave' over Fram:

Looks cold in Kane though, which is the topic of this thread?
Title: Re: The Nares Strait thread
Post by: A-Team on January 26, 2015, 11:28:26 AM
Just to follow up on MikeAinOz's link above on the time series of ice export through Nares: that story references two papers, both online, by R Kwok that provide a 13 year record. A 2014 poster suggests that a follow-up study is well underway. It is hard to discern a trend given natural variability and a fairly short record.

A O'Brien 2014. Variability of Arctic Sea Ice Export and Deformation through Nares Strait
http://www.candac.ca/create/ss2014/posters/obrien_ashley_CSI_poster_2014.pdf (http://www.candac.ca/create/ss2014/posters/obrien_ashley_CSI_poster_2014.pdf)

R Kwok 2010. Large sea ice outflow into Nares in 2007
http://onlinelibrary.wiley.com/doi/10.1029/2009GL041872/full (http://onlinelibrary.wiley.com/doi/10.1029/2009GL041872/full)

R Kwok 2005. Variability of Nares Strait ice flux
http://onlinelibrary.wiley.com/doi/10.1029/2005GL024768/full (http://onlinelibrary.wiley.com/doi/10.1029/2005GL024768/full)
Title: Re: The Nares Strait thread
Post by: viddaloo on January 26, 2015, 02:54:17 PM
Check out this (http://cci-reanalyzer.org/DailySummary/) 20C anomaly 'heatwave' over Fram:
Looks cold in Kane though, which is the topic of this thread?
I bet we'll see repercussions of this in the Lincoln Sea above the Nares Strait, as the collapse zones of the two straits are practically already merged. And this heatwave can easily spread to the Nares itself, plus there is a 10C anomaly already in the Lincoln. But other than that, I agree with you, we should stay on topic and stick to the Nares.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 26, 2015, 03:00:41 PM
Sentinel images of 01-24 and 01-25 of "Kennedy" (Robeson Channel and a spot of Hall Basin and Lincoln Sea) show ice moving into Robeson Channel going about 30 km (in one day) and floes already in the channel going up to 65 km. 

There are no Sentinel images showing the active flow in Kane Basin or the north end of Baffin Bay on 01-25, so cannot tell how fast ice is moving there.
Title: Re: The Nares Strait thread
Post by: solartim27 on January 26, 2015, 07:48:09 PM
Nice coverage today.  The latest large floe is off of Peterman at one of the usual sticking points, moved really far from yesterday. There's one more large chunk in Lincoln getting ready to try to plug it up, could that be the last chance of an ice bridge this year?  I think so, nothing else looks big enough.
 
http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150126s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150126s01a.ASAR.jpg)

http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/20150126s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/20150126s01a.ASAR.jpg)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 26, 2015, 09:50:19 PM
Sonia's iceberg(?) went about 130 km in two days.  On 01-26 Sentinel it is in the middle of the actively flowing channel in the (top) middle of Kane Basin.  (It is 7 and 30 km behind two floes that it was 20 and 65 km behind on the 01-24 Sentinel image.)

Floes leaving Nares Strait and entering Baffin Bay traveled about 45 km in two days.  Floes just in Robeson Channel went 20 km this past one day.  Floes in Lincoln Sea moved 4 or 5 km in one day. 

Title: Re: The Nares Strait thread
Post by: MikeAinOz on January 26, 2015, 10:51:50 PM
Hey A-Team thanks for a great post and some great links. The short period and changing conditions make it difficult to say anything but the obvious, that it's a little late in the season for ice arches, but we should see some soon  :). A little more googling took me to Icy Seas at http://icyseas.org/tag/nares-strait/ (http://icyseas.org/tag/nares-strait/)  and Andreas Muenchow's fine post on the physics of the Nares Strait, which left me a more informed on the subject.
Title: Re: The Nares Strait thread
Post by: Sonia on January 27, 2015, 02:38:17 AM
A-Team, thanks.  The papers were interesting.  The attached graph from the 2010 paper shows how February is a typical time for ice outflow to drop, so I think arch formation this year isn't overdue at all here in January still.

Tor, thanks for running the numbers.  Yep, ice is still ripping right through the Kane.  A day of light winds wasn't enough to let the passage freeze up and now the northerlies have returned.  I guess I'll go back to watching for a show stopper in the Robeson.
Title: Re: The Nares Strait thread
Post by: viddaloo on January 27, 2015, 12:03:49 PM
http://www.woksat.info/wos.html (http://www.woksat.info/wos.html)

I find the above site useful for daily 'snaps' of Nares/Lincoln and Beaufort? It appears the sudden halt in the Gyre has lead to a , now familiar, fragmentation across Beaufort? Any 'relaxation' in Lincoln provides 'space' for the Beaufort event to relax into?

This site is great, Gråbein!

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fwww.woksat.info%2Fetcxa26%2Fxa26-1225-e-grn-n.JPG&hash=7faaf0e6d14b87649a1f1ddb30244703)
Title: Re: The Nares Strait thread
Post by: viddaloo on January 27, 2015, 12:28:33 PM
12 UTC today (http://cci-reanalyzer.org/Forecasts/) over Nares: 15–20C above normal.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 27, 2015, 05:07:24 PM
Thanks, viddaloo for putting the http://www.woksat.info/wos.html (http://www.woksat.info/wos.html) link (daily images of entire Nares Strait, etc.) on this thread.  It is quite amazing.
Title: Re: The Nares Strait thread
Post by: viddaloo on January 27, 2015, 05:31:49 PM
You're welcome, Tor.

Lincoln Sea–centric winter heatwave: Wonder how it all will look in a couple days when the clouds clear over Fram & Nares.

Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 27, 2015, 09:17:31 PM
Interesting event happening in the Lincoln Sea, per the very partial Sentinel image dated 2015-01-27.  While floes within the Lincoln Sea continue to move toward Nares Strait at 5 or so Km per day, the ice against Greenland has lifted off a few km in the past day.

Rather exciting for a 'watching ice disappear in the winter' sort of guy. :D
Title: Re: The Nares Strait thread
Post by: viddaloo on January 27, 2015, 10:44:45 PM
While floes within the Lincoln Sea continue to move toward Nares Strait at 5 or so Km per day, the ice against Greenland has lifted off a few km in the past day.

Probably related to the so–called heatwave? Do you reckon the pull on it is from the Nares?
Title: Re: The Nares Strait thread
Post by: solartim27 on January 28, 2015, 01:16:37 AM
Wind.
Title: Re: The Nares Strait thread
Post by: viddaloo on January 28, 2015, 08:45:01 AM
Interesting event happening in the Lincoln Sea, per the very partial Sentinel image dated 2015-01-27.  While floes within the Lincoln Sea continue to move toward Nares Strait at 5 or so Km per day, the ice against Greenland has lifted off a few km in the past day.

Rather exciting for a 'watching ice disappear in the winter' sort of guy. :D

Almost looks like the Nares Strait was extended beyond the north tip of Greenland?

Title: Re: The Nares Strait thread
Post by: viddaloo on January 28, 2015, 12:56:35 PM
Looks like that's just what happened.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FLincoln%2F201501280658.NOAA.jpg&hash=6b5eccf5d6ecb7313a21ac309038c6ee)
Title: Re: The Nares Strait thread
Post by: Laurent on January 28, 2015, 02:23:14 PM
Ouahou...could it be that the Atlantic is surfacing in arctic ?...let's see...
Thanks for the updates.
Title: Re: The Nares Strait thread
Post by: viddaloo on January 28, 2015, 04:58:09 PM
Yup. Meet the new, extended Nares Strait. Twice the length.
Title: Re: The Nares Strait thread
Post by: Jim Hunt on January 28, 2015, 05:07:33 PM
A cross post of the AMSR2 version also:

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fforum.arctic-sea-ice.net%2Findex.php%3Faction%3Ddlattach%3Btopic%3D997.0%3Battach%3D13354%3Bimage&hash=3c9b02e1140a8f7bbfe46546660b7e58)
Title: Re: The Nares Strait thread
Post by: viddaloo on January 28, 2015, 05:38:20 PM
The Arctic is now officially toast, guys. Waiting for them melt records to fall.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fwww.woksat.info%2Fetcxa28%2Fxa28-1344-e-apt.JPG&hash=207e8bb987ef067148b4dafd3d5b2a37)
Title: Re: The Nares Strait thread
Post by: viddaloo on January 28, 2015, 05:47:41 PM
Hat–tip to Arctic News (http://arctic-news.blogspot.de/2014/06/arctic-atmospheric-methane-global-warming-veil.html):

Quote
´When the Arctic ice cap finally melts towards the end of next year, the Arctic sea will be aggressively heated by the sun and the Gulf Stream. The cold Arctic air will then be confined to the Greenland Ice cap and the hot Arctic air with its methane will flow south to the United States to further heat up the Gulf Stream, setting up an anticlockwise circulation around Greenland. Under these circumstances Great Britain and Europe must expect even more catastrophic storm systems, hurricane force winds and massive flooding after the end of next year, due to a further acceleration in the energy transport of the Gulf Stream.´
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 28, 2015, 06:22:41 PM
I'm also interested in the cracks that both follow and are perpendicular to the Ellesmere Island coast in and near the Lincoln Sea that show up in two recent posts from viddaloo's (from this morning) .

Here is a train or jumble of thoughts (unrelated to the ice pulling away from the Greenland and Ellesmere coasts):
1) Arctic ice piles up against Canadian islands and Greenland due to prevailing winds and currents.
2) An open Nares Strait is allowing export of ice from the Lincoln Sea.
3) Arctic ice that is shoved toward the Lincoln Sea is able to move faster and easier than ice that has to buckle, fold and raft (or ice that is behind this buckling and rafting ice) if it is to move much at all. In fact, ice heading toward the Lincoln Sea will do very little buckling and rafting.
4) With a little time, cracks facilitate more ice being channeled towards the Lincoln Sea.
5) Until Nares Strait is closed down, the Arctic ice in this funnel area will be more fractured and thinner (less rafted, etc.) than it would be otherwise.  If Nares never closes down (as in 2006-07), the following early summer melt may have a significant head start.

6) Fram Strait provides the same (but much larger) outlet, but as it never closes, its processes are part of the status quo.
Title: Re: The Nares Strait thread
Post by: viddaloo on January 28, 2015, 06:47:41 PM
Wind.

Nah.

Sentinels show the ice near the coast melting from below due to the hot ocean currents.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FNord%2F20150128s01a.ASAR.jpg&hash=c518d8041d332942bbc1ee7dcbf98edc)
Title: Re: The Nares Strait thread
Post by: solartim27 on January 28, 2015, 07:23:23 PM
I don't know about bottom melt, but the motion is from wind, look at sentinel from the past three days up the coast at Morris Jessup. 

In the strait, NOAA radar shows the larger chunk moving slowly towards the narrow choke point, mild winds flowing to the north against the water flow, dying down later today.
http://www.weatheronline.co.uk/weather/maps/city?LANG=en&CEL=C&SI=mph&CONT=euro&LAND=GL&REGION=0004&WMO=x9500&LEVEL=52&R=310&NOREGION=1 (http://www.weatheronline.co.uk/weather/maps/city?LANG=en&CEL=C&SI=mph&CONT=euro&LAND=GL&REGION=0004&WMO=x9500&LEVEL=52&R=310&NOREGION=1)

http://www.windfinder.com/weather-maps/forecast/greenland#2/71.7/-42.2 (http://www.windfinder.com/weather-maps/forecast/greenland#2/71.7/-42.2)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 28, 2015, 08:45:55 PM
The following distances use Sentinel 01-26 and 01-28 images (2 days apart).

There appears to be a bit of a bottleneck in Smith Sound (south end of Nares Strait):At the north end of Nares Strait (there being a gap in Sentinel coverage):My big question:  What became of the large floe (13 x 20 km) that was in Hall Basin on 01-26?  Did it slip by Hans Island? Get stuck there? Shatter?  (I’m going to guess “shatter”.)

As always, Sentinel images are available at http://ocean.dmi.dk/arctic/kennedy.uk.php (http://ocean.dmi.dk/arctic/kennedy.uk.php).
Title: Re: The Nares Strait thread
Post by: jdallen on January 28, 2015, 08:55:13 PM
I don't know about bottom melt, but the motion is from wind, look at sentinel from the past three days up the coast at Morris Jessup. 

In the strait, NOAA radar shows the larger chunk moving slowly towards the narrow choke point, mild winds flowing to the north against the water flow, dying down later today.
http://www.weatheronline.co.uk/weather/maps/city?LANG=en&CEL=C&SI=mph&CONT=euro&LAND=GL&REGION=0004&WMO=x9500&LEVEL=52&R=310&NOREGION=1 (http://www.weatheronline.co.uk/weather/maps/city?LANG=en&CEL=C&SI=mph&CONT=euro&LAND=GL&REGION=0004&WMO=x9500&LEVEL=52&R=310&NOREGION=1)

http://www.windfinder.com/weather-maps/forecast/greenland#2/71.7/-42.2 (http://www.windfinder.com/weather-maps/forecast/greenland#2/71.7/-42.2)

I concur that wind is what we see driving the movement.  Rather than bottom melt, I'd say any exchange from depth at this time of year would be more likely expressed in less thickening of the ice. 

At any given time, far and away enough heat resides in the Arctic ocean to melt the rather pitiable skin of ice which covers it, and to keep it melted.  What prevents that is lack of circulation from depth, and attendant thermo and haloclines.

I don't sense the flow from the Atlantic will loop anti-clockwise around Greenland.  They physics of motion aren't right, and the constraints of ocean bottom topography are wrong.  The tendency of momentum is to carry the flow NE - and we can see that expressed in the melting/lack of ice formation which takes place north and west of Svalbard.

However, wind on the current fractured, weakened pack (driven by cyclone after cyclone after cyclone! roaring up the US Eastern Seaboard, dragging huge amounts of heat with them, and slamming into NE Europe and the Barents...) will cause movement.  That movement at the surface can cause ekman transport.  That can cause local movement of heat from depth.   Not enough I think to cause serious bottom melt, but enough to restrict growth and strengthening of the pack.

I agree that the general havoc we see with Nares and the movement of ice may have dangerous implications for the coming melt season.

Thank for ferreting out the images, Jim and Vidd.
Title: Re: The Nares Strait thread
Post by: viddaloo on January 28, 2015, 09:21:49 PM
12 UTC today (http://cci-reanalyzer.org/Forecasts/) over Nares: 15–20C above normal.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fforum.arctic-sea-ice.net%2Findex.php%3Faction%3Ddlattach%3Btopic%3D176.0%3Battach%3D13313%3Bimage&hash=8e5e363c92013257ddacc3382aabe98b)
Heat.
Title: Re: The Nares Strait thread
Post by: Sonia on January 28, 2015, 10:56:58 PM
Wind.
Title: Re: The Nares Strait thread
Post by: viddaloo on January 28, 2015, 11:18:20 PM
If you want to turn a part of the Arctic Ocean into a raging river 10 times the size of the Amazon you need more than just wind. Heat has been suggested, as heat has been scientifically proven to have devastating effects on ice, for instance in the Arctic where huge amounts of sea ice has disappeared because of global warming.
Title: Re: The Nares Strait thread
Post by: Jim Hunt on January 29, 2015, 12:45:50 AM
Wind - http://econnexus.org/the-day-after-tomorrow-coming-soon/ (http://econnexus.org/the-day-after-tomorrow-coming-soon/)
Title: Re: The Nares Strait thread
Post by: A-Team on January 29, 2015, 01:00:52 AM
Whatever. Lincoln Sea is falling apart. Seems like Andreas M showed with tide gauges (see above) that the Arctic Ocean is 6-8" higher than Baffin Bay so the current is always to the south regardless of the wind. I've spent some weeks on the Amazon -- it is hardly moving. And yes, you can see the tree line on both sides as far down as Manaus.

And here's something to ponder (on the appropriate forum):

Arctic freshwater export: Status, mechanisms, and prospects
TWN Haine 2013
https://www.sciencedirect.com/science/article/pii/S0921818114003129?np=y (https://www.sciencedirect.com/science/article/pii/S0921818114003129?np=y)

Quote
Large freshwater anomalies clearly exist in the Arctic Ocean. For example, liquid freshwater has accumulated in the Beaufort Gyre in the decade of the 2000s compared to 1980–2000, with an extra ≈ 5000 km3 — about 25% — being stored. The sources of freshwater to the Arctic from precipitation and runoff have increased between these periods (most of the evidence comes from models).

Despite flux increases from 2001 to 2011, it is uncertain if the marine freshwater source through Bering Strait for the 2000s has changed, as observations in the 1980s and 1990s are incomplete. The marine freshwater fluxes draining the Arctic through Fram and Davis straits are also insignificantly different. In this way, the balance of sources and sinks of freshwater to the Arctic, Canadian Arctic Archipelago (CAA), and Baffin Bay shifted to about 1200 ± 730 km3 yr− 1 freshening the region, on average, during the 2000s.

The observed accumulation of liquid freshwater is consistent with this increased supply and the loss of freshwater from sea ice. Coupled climate models project continued freshening of the Arctic during the 21st century, with a total gain of about 50,000 km3 for the Arctic, CAA, and Baffin Bay (an increase of about 50%) by 2100. Understanding of the mechanisms controlling freshwater emphasizes the importance of Arctic surface winds, in addition to the sources of freshwater.

The wind can modify the storage, release, and pathways of freshwater on timescales of O(1–10) months. Discharges of excess freshwater through Fram or Davis straits appear possible, triggered by changes in the wind, but are hard to predict. Continued measurement of the fluxes and storage of freshwater is needed to observe changes such as these.
Title: Re: The Nares Strait thread
Post by: viddaloo on January 29, 2015, 02:02:51 AM
I think the ferryman who said that was far east of Manaus, where the river is far wider. However, with the tall mountains around the Nares, I suspect you should be able to see some land even mid–fjord.
Title: Re: The Nares Strait thread
Post by: solartim27 on January 29, 2015, 04:40:30 AM

My big question:  What became of the large floe (13 x 20 km) that was in Hall Basin on 01-26?  Did it slip by Hans Island? Get stuck there? Shatter?  (I’m going to guess “shatter”.)

As always, Sentinel images are available at http://ocean.dmi.dk/arctic/kennedy.uk.php (http://ocean.dmi.dk/arctic/kennedy.uk.php).

Sentinel finally came through.  It is on Hans island, about to be hit from behind by a good sized chunk.  Hope tomorrows pics come through, should be interesting.
http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150128s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150128s01a.ASAR.jpg)
Title: Re: The Nares Strait thread
Post by: viddaloo on January 29, 2015, 07:10:35 AM
Uni–Bremen January 26—28th.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 29, 2015, 05:23:45 PM
Comparing the 01-28 and 01-26 Sentinel images for Kennedy (http://ocean.dmi.dk/arctic/kennedy.uk.php (http://ocean.dmi.dk/arctic/kennedy.uk.php)) – two days:
 

What will the next episode bring?

(Other 01-28 and 01-26 Sentinel images were compared yesterday.)
Title: Re: The Nares Strait thread
Post by: viddaloo on January 29, 2015, 05:55:14 PM
  • The large floe near Petermann Fjord went 65 km.  I think it bounced off Hans Island a km (at time of 01-28 image) and is at least temporarily stuck.  Floes would be able to get around it, but this might mark 'the beginning of the end'.

Thx, Bejnar. PS: What happens if "the end" begins at Hans? How far below Lincoln Sea are we talking in terms of sea–level, and how would this affect transport into the strait?
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 29, 2015, 06:29:18 PM
... PS: What happens if "the end" begins at Hans? How far below Lincoln Sea are we talking in terms of sea–level, and how would this affect transport into the strait?
A bridge that forms anywhere in Nares Strait will ultimately stop the export of ice from the Lincoln Sea.  Without export, the Lincoln Sea will either be filled by thickish ice 'from the north' or new ice which will thicken (due to cold, and due to buckling and rafting from the pressure caused by winds/currents), and then winter ice movement and stresses would be 'back' to the non-2006-7 winter norm.

I don't think sea level issues are relevant, once a sturdy ice bridge forms.  Arctic water will continue to pour through Nares Strait under the ice functionally unimpeded.
Title: Re: The Nares Strait thread
Post by: Sonia on January 29, 2015, 06:40:08 PM
Smith Sound looks like the end to me.  Winds were from south and brisk for two days.  They have started to turn now but it looks like they slowed the ice enough to promote arch formation.

I didn't measure accurately but it looks like my maybe-iceberg went just 40 km or so between the 1-26 and 1-28 Sentinal images and is still well upstream of the nascent arch.

But in another day the wind will have filled in stronger from the north and my iceberg, if it is, should be pushing hard to get through.  We'll see how well the arch holds up.
Title: Re: The Nares Strait thread
Post by: viddaloo on January 29, 2015, 06:57:11 PM
A bridge that forms anywhere in Nares Strait will ultimately stop the export of ice from the Lincoln Sea.

You'd have to fill up the entire strait with ice first, then, all the way up to Lincoln Sea. For what it's worth, I don't think that's likely to happen this year.
Title: Re: The Nares Strait thread
Post by: Andreas Muenchow on January 30, 2015, 12:14:37 AM
I think the ferryman who said that was far east of Manaus, where the river is far wider. However, with the tall mountains around the Nares, I suspect you should be able to see some land even mid–fjord.
On a clear summer day the visibility in Nares Strait exceeds 100 km, so unless it is foggy (rare in summer), one always sees both Greenland and Ellesmere Island that are only 30-40 km apart north of 80 N. This is a very typical, little hazy picture from August-5, 2012. View is to the north by north-west. The land just above the horizon is Cape Baird about 100 km to the north from our main mooring location in Kennedy Channel. Helicopter is trying to find the best route to very loose ice. Funny thing to compare this to the MODIS image for that day at http://muenchow.cms.udel.edu/Nares2012/Band01/T2012218.pdf (http://muenchow.cms.udel.edu/Nares2012/Band01/T2012218.pdf) or any other source if such imagery.
Title: Re: The Nares Strait thread
Post by: solartim27 on January 30, 2015, 06:29:09 AM
Coverage was not good today, Looks like the chunk remains on Hans island and the bottleneck at the south end is getting bigger, but still letting ice pass through.  Hard to say for certain, are the winds pushing everything up against the Greenland side of the strait?  Very mild winds through tomorrow.  No motion at all up n the Lincoln.

http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/201501291320.NOAA.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/201501291320.NOAA.jpg)

http://ocean.dmi.dk/arctic/images/MODIS/Kane/201501291825.NOAA.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/201501291825.NOAA.jpg)
Title: Re: The Nares Strait thread
Post by: solartim27 on January 30, 2015, 03:34:31 PM
South Nares is currently plugged
http://ocean.dmi.dk/arctic/images/MODIS/Kane/201501300641.NOAA.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/201501300641.NOAA.jpg)
Title: Re: The Nares Strait thread
Post by: Laurent on January 30, 2015, 05:10:29 PM
Not completely yet, the ice cream in Baffin is thickening so yes it may become impossible for the ice to escape Nares strait but...let's see if it does really jam Nares export.
http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticictn_nowcast_anim30d.gif (http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticictn_nowcast_anim30d.gif)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 30, 2015, 05:27:59 PM
Sonia called it on the 29th: it looks to me like south Kane Basin (just north of Smith Sound) has an ice bridge on NOAA AVHRR images from yesterday and today (http://ocean.dmi.dk/arctic/kane.uk.php (http://ocean.dmi.dk/arctic/kane.uk.php)).  But I recall that 'the shark' appeared to be stuck on Joe Island for a day or so. I do look forward to Sentinel images!

As I understand it, it is generally cold enough to constantly freeze surface sea water 'up there', so between the floes that separate out in the Lincoln Sea and that accelerate down Nares Strait, thin ice forms, but it doesn't get thick because it is constantly getting exported.  If the bridge holds, this thin ice will fairly quickly thicken enough to slow, then stop floes headed downstream, and most of (or at least a great deal of) Nares Strait will then be covered in 1st year ice with thicker floes and mélange stuck in it.

So when, this winter, will the last floe leave the Lincoln Sea and enter Robeson Channel (north end of Nares Strait)?  I'll guess February 5 (if bridge holds).
Title: Re: The Nares Strait thread
Post by: Espen on January 30, 2015, 08:01:42 PM
Knock knock knocking on Hans Ø:

(Jan 28 - Jan 30)

Lets not hope it moves the island, then a major diplomatic war will start!
There are plenty of poor "patriotic" politicians on both side of the "conflict"
Title: Re: The Nares Strait thread
Post by: Wipneus on January 31, 2015, 08:39:18 AM
Kane 28-30 January. The new arch is keeping the ice blocked from half way the basin.

(click to animate)
Title: Re: The Nares Strait thread
Post by: solartim27 on January 31, 2015, 08:59:23 AM
I would love to see what that looks like from a boat, or walking across it.  Strong winds developing next Tuesday and Wednesday, that will show us if it's stable or not.
http://www.windfinder.com/weather-maps/forecast/greenland#4/79.34/-55.72 (http://www.windfinder.com/weather-maps/forecast/greenland#4/79.34/-55.72)

So when, this winter, will the last floe leave the Lincoln Sea and enter Robeson Channel (north end of Nares Strait)?  I'll guess February 5 (if bridge holds).

Shouldn't the betting pool be for when it breaks?  When's the next full moon?
Title: Re: The Nares Strait thread
Post by: Espen on January 31, 2015, 09:51:09 PM
How to build a bridge in the arctic Jan 28 - Jan 31:
Title: Re: The Nares Strait thread
Post by: Espen on January 31, 2015, 10:33:25 PM
Ice Cruncher for sale (And I don't care what the Danes or Canadians think):
Title: Re: The Nares Strait thread
Post by: DrTskoul on January 31, 2015, 10:53:21 PM
I would love to hear the sound!!!!
Title: Re: The Nares Strait thread
Post by: Espen on January 31, 2015, 11:06:09 PM
I would love to hear the sound!!!!

How about this: https://www.youtube.com/watch?v=Q0utAHY3xo4 (https://www.youtube.com/watch?v=Q0utAHY3xo4)
Title: Re: The Nares Strait thread
Post by: Espen on January 31, 2015, 11:36:18 PM
Or this: https://www.youtube.com/watch?v=qyE9vFGKogs (https://www.youtube.com/watch?v=qyE9vFGKogs)

A fantastic story ;)
Title: Re: The Nares Strait thread
Post by: Wipneus on February 02, 2015, 08:51:33 AM
The newly formed arch is well visible on the UH AMSR2 sea ice concentration maps.
Title: Re: The Nares Strait thread
Post by: Wipneus on February 03, 2015, 08:08:44 AM
Nares Strait, Kane Basin Jan 31 & Feb 2. The jam extends probably to the top of the basin by now.
Title: Re: The Nares Strait thread
Post by: viddaloo on February 03, 2015, 01:37:01 PM
Another Greenland heatwave. Could it loosen up the Kane bottleneck?
Title: Re: The Nares Strait thread
Post by: solartim27 on February 03, 2015, 05:34:04 PM
Granted, the anomaly is large, but with a high temp of -20 C in the next week I think it's unlikely.

http://www.weatheronline.co.uk/weather/maps/city?LANG=en&CEL=C&SI=mph&CONT=euro&LAND=GL&REGION=0004&WMO=x9500&LEVEL=52&R=310&NOREGION=1 (http://www.weatheronline.co.uk/weather/maps/city?LANG=en&CEL=C&SI=mph&CONT=euro&LAND=GL&REGION=0004&WMO=x9500&LEVEL=52&R=310&NOREGION=1)

http://en.wikipedia.org/wiki/Qaanaaq (http://en.wikipedia.org/wiki/Qaanaaq)
Title: Re: The Nares Strait thread
Post by: viddaloo on February 03, 2015, 06:31:26 PM
I think it can, if it goes all the way to the strait.
Title: Re: The Nares Strait thread
Post by: Jester Fish on February 03, 2015, 11:35:12 PM
I agree with Solar.... large anomaly, yes; mid-latitude heat getting pumped WAY north, yes; melting temps, NO.

Title: Re: The Nares Strait thread
Post by: viddaloo on February 04, 2015, 11:40:25 AM
Totally agree with Jester Fish,
large anomaly, yes; mid-latitude heat getting pumped WAY north, yes; melting temps, NO.
but it may loosen up the Kane bottleneck, which is the topic of discussion here.
Title: Re: The Nares Strait thread
Post by: Rubikscube on February 05, 2015, 01:20:04 AM
but it may loosen up the Kane bottleneck, which is the topic of discussion here.

I would assume the primary reason why hot weather should affect Nares is that such weather will likely be accompanied by strong winds, and right now, really strong winds would be the only thing that could possibly make Nares move again. However, I don't see that coming in the forecast.

Just let it go dog. It's over :D.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on February 05, 2015, 04:20:20 PM
The bridge in Smith Sound/Kane Basin is standing (arching?) strong (per 2015-02-04 Sentinel image), but ice is still entering Robeson Channel from the Lincoln Sea (per NOAA AVHRR images.  Ice continues to break into discrete floes in the Lincoln Sea.  A huge floe is approaching the entrance to Nares.  Will it block the entrance or break up upon making contact with Ellesmere or Greenland shores?  (Every other floe, so far, has shattered when confronted with terra firma this season (some on their second or third bounce).)
Title: Re: The Nares Strait thread
Post by: solartim27 on February 05, 2015, 10:05:08 PM
I think it's just a cloud, but the shape is weird. Worth checking on later.

Title: Re: The Nares Strait thread
Post by: Jester Fish on February 05, 2015, 10:06:57 PM
Does anyone have a sense of whether the degree to which ice floes are breaking upon impact with Ellesmere or Greenland this winter is different from the past?  It seems to me, that if there is a higher rate of breakage, that could indicate reduced ice integrity (i.e. softer, thinner, fractured, etc..) which has obvious implications for the melt season.  If breakage is similar, then well it's similar and not much can be concluded. 
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on February 06, 2015, 01:57:36 PM
Except for a couple (maybe exactly 2) times in the past, no ice flowed into Nares Strait in January or February (it was iced over), so there might not be significant data to compare.  (I don't know what satellite imagery is available. Data at http://ocean.dmi.dk/arctic/kennedy.uk.php (http://ocean.dmi.dk/arctic/kennedy.uk.php) goes back to about 2010.)  On the other hand, I'm not aware of Nares ever getting closed down by a floe after it opened during the summer.  (On the third hand, I may not have been watching close enough, so maybe I just don't know!)

This year's ice bridge in Smith Sound/Kane Basin was not caused by a single floe.

It is just coming to me that, although the terms "ice bridge" and "ice arch" are used synonymously, a 'bridge' may be more appropriate when a floe blocks the surface from shore to shore, whereas an 'arch' may be more appropriate when local ice forms the main structure that stops surface flow.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on February 06, 2015, 02:07:09 PM
The floe that bounced on Hans Island a couple of times before breaking (a couple days ago) had its larger more intact 'half' on the south of Hans Island where it looked like it might get stuck behind Franklin Island.  Well, it shattered.  (The small floe with a huge black mark [per the Sentinel image] that was just behind the potentially-blocking floe is now right next to Hans Island, so we can tell about where the shattered floe should be.)

There is still movement at the north end of Nares Strait.
Title: Re: The Nares Strait thread
Post by: Wipneus on February 07, 2015, 08:43:00 AM
The movement is actually in reverse, ice moving backward due to 50km/h SW winds.

(click to animate)
Title: Re: The Nares Strait thread
Post by: johnm33 on February 07, 2015, 11:05:14 AM
Just checked the winds close up on http://earth.nullschool.net/#current/wind/surface/level/orthographic=-0.48,86.69,2048 (http://earth.nullschool.net/#current/wind/surface/level/orthographic=-0.48,86.69,2048) just a chance they could force the tides and smash the arch.
Title: Re: The Nares Strait thread
Post by: solartim27 on February 07, 2015, 07:34:56 PM
The winds were supposed to let up, still too cloudy to see clearly, but there seems to be a sudden increase of ice floes in Smith Sound.  Todays NOAA image on top.
Title: Re: The Nares Strait thread
Post by: viddaloo on February 07, 2015, 09:55:44 PM
but it may loosen up the Kane bottleneck, which is the topic of discussion here.
I would assume the primary reason why hot weather should affect Nares is that such weather will likely be accompanied by strong winds, and right now, really strong winds would be the only thing that could possibly make Nares move again. However, I don't see that coming in the forecast.

Just let it go dog. It's over :D.
"I fear, Baldrick, that you will soon be eating those badly chosen words." Edmund Blackadder (http://en.wikiquote.org/wiki/Blackadder)
Title: Re: The Nares Strait thread
Post by: solartim27 on February 07, 2015, 10:49:32 PM
Sentinel is in, partial collapse of the arch, blown up to the north, hard to say what will happen next.  I just looked at Kennedy pics, and floes that were well past Franklin Island are now upstream again.  Big addition of ice back into Lincoln as well.

http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150207s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150207s01a.ASAR.jpg)

2 days ago  http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150205s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150205s01a.ASAR.jpg)
Title: Re: The Nares Strait thread
Post by: Sonia on February 07, 2015, 11:26:48 PM
Wow, I sure didn't expect that.  I really expected to ice in the Kane to be frozen fast for the winter.
Title: Re: The Nares Strait thread
Post by: Neven on February 08, 2015, 12:13:11 AM
Rewind! Pretty cool.  8)
Title: Re: The Nares Strait thread
Post by: be cause on February 08, 2015, 01:05:00 AM
 Must be quietly becoming the most interesting thread on the planet . Thanks .

The winds certainly suit Fram export in a big way over the next week and ice should pour into Lincoln as well . The chances of Nares flowing again seem high .. 
Title: Re: The Nares Strait thread
Post by: tombond on February 08, 2015, 05:58:32 AM
Must be quietly becoming the most interesting thread on the planet . Thanks .

Can only agree!
Title: Re: The Nares Strait thread
Post by: solartim27 on February 08, 2015, 07:25:50 AM
Tried making a gif of the motion at Kennedy.  I can make out three floes easily, labeled A, B, and C.  Hope it works.  Might have to click on the pic to animate it.

Title: Re: The Nares Strait thread
Post by: Espen on February 08, 2015, 12:56:19 PM
The southern arch near Smith Sound is retreating to the north (interesting behaviour):

Title: Re: The Nares Strait thread
Post by: Shared Humanity on February 08, 2015, 02:49:45 PM
The southern arch near Smith Sound is retreating to the north (interesting behaviour):

I wonder if the arch will maintain its integrity if the wind changes and it moves south again. Will it plug the hole or shatter?
Title: Re: The Nares Strait thread
Post by: viddaloo on February 08, 2015, 05:28:18 PM
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fwww.woksat.info%2Fetcxb08%2Fxb08-1322-h-grn-n.JPG&hash=eb77c9738e4fd288bb9bcd84c212ad37)
Title: Re: The Nares Strait thread
Post by: Rubikscube on February 09, 2015, 12:51:13 AM
but it may loosen up the Kane bottleneck, which is the topic of discussion here.
I would assume the primary reason why hot weather should affect Nares is that such weather will likely be accompanied by strong winds, and right now, really strong winds would be the only thing that could possibly make Nares move again. However, I don't see that coming in the forecast.

Just let it go dog. It's over :D.
"I fear, Baldrick, that you will soon be eating those badly chosen words." Edmund Blackadder (http://en.wikiquote.org/wiki/Blackadder)
I can assure you that right now all possible measures are being taken to eat those words :-[.
Title: Re: The Nares Strait thread
Post by: Wipneus on February 09, 2015, 07:58:42 AM
The view of the blowing arch seen by the AMSR2 satellite.
Title: Re: The Nares Strait thread
Post by: Wipneus on February 09, 2015, 10:50:53 AM
In the middle of the Kane is still Sonia's ice floe/berg. Hi res (10m/pix) Sentinel image from Feb 6.
Title: Re: The Nares Strait thread
Post by: viddaloo on February 09, 2015, 10:54:47 AM
To summarise, the Nares Strait is a saltwater 'river' carrying 10 times the amount of water of the Amazon — the world's biggest river — and the Strait's wider at the narrowest than even the nether regions of the Amazon. The reason for the near–constant running of the Nares Strait 'river' is the difference in sea level provided primarily by the Beaufort Gyre. Other Canadian Archipelago straits are also feeling this difference. To give you a perspective of the width: In the nether regions of the Amazon river you cannot see the shore from 'mid–fjord', the Nares is wider but here you can see the shore from mid–fjord because of the landscape, with mountains and giant glaciers.

The Nordic or Viking name of the Strait is unsure. It is certainly not Straumfjord, which is more likely the St. Lawrence area or even the Hudson River in New York. Vikings hunted and traded with the inuits in the Nares area, leaving remains for instance on Ruin Island, calling the inuits 'skrælinger', meaning presumably '(seal) skin–dressed'. Norse vikings avoided the Black Death that arrived in Bergen because the ship lines were disrupted by the same pest, but at the same time the supply line was cut and the Garðar bishop seat was discontinued. Vikings who regularly went to America (Vinland) to get timber for house– and boat construction also most likely 'disappeared' from Greenland by abandoning their settlements and settling with the inuits and/or indians of North America. A very popular ball–game among the Norse was found by anthropologists among the native Americans in very similar versions using the same bats or tools. So our Northern European ancestors were there, playing ball with the locals, long before they were 'discovered' by our Southern European cousins.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fhistorienet.no%2Ffiles%2Fbonnier-his%2Fimagecache%2F630x420%2Fpictures%2F1563_17_0405_03.jpg&hash=299131a0a1cdd49eb6dd76ac928db989)
Title: Re: The Nares Strait thread
Post by: solartim27 on February 09, 2015, 07:39:56 PM
Ice field from South Nares through Lincoln is mostly stationary, with light winds forecast through the week.  Climate Reanalyzer shows a chance for some action next Saturday, but it's not clear to me which direction the wind will be in.

http://cci-reanalyzer.org/Forecasts/ (http://cci-reanalyzer.org/Forecasts/)

Title: Re: The Nares Strait thread
Post by: Tor Bejnar on February 09, 2015, 08:47:46 PM
I spend a weekend with family and friends and Nares Strait ice goes back to where it came from! Or did DMI just rename some old images to throw us off?;D

The 02-09 Sentinel image of Kane Basin shows that ice has generally moved 5 to 7 km 'upstream' since the 02-07 image (including Sonia's ice floe/berg).  Some ice that was near the old bridge's edge has moved more toward Ellesmere Island than, strictly, upstream.  The numerous leads in the ice suggests to me that it has actually started to move south again, with the 'southern' ice moving a mite faster than the 'more-northern' ice.  I don't really believe the 'more-northern' ice is travelling 'north' more quickly (but this would also explain the leads).

It has been a delight to look at some of the images made available through http://www.polarview.aq/arctic (http://www.polarview.aq/arctic) - thanks to the person on some other thread who published it [edit: Thanks, Arcticio, for posting on Neven's blog.].  These (and the 02-09 Sentinel image through DMI) show the fractured nature of the old bridge.  I don't see any way for it to reestablish itself, and expect a lot more ice to pass through Smith Sound this winter*.  (This, of course, doesn't prevent it from reestablishing itself. :P )

* - Is it still winter?  I saw lots of bloodroot blooming in my yard this weekend. [Edit: +1s and a -1 C lows in coming week's forecast. I guess it still is winter here in north Florida.](http://en.wikipedia.org/wiki/Sanguinaria (http://en.wikipedia.org/wiki/Sanguinaria))
Title: Re: The Nares Strait thread
Post by: Jim Hunt on February 09, 2015, 09:30:44 PM
Many thanks to Arcticio for pointing me at PolarView (http://greatwhitecon.info/2015/02/new-antarctic-sea-ice-resources/#Sentinel), which readily revealed this Sentinel image of "the arch" earlier today:
Title: Re: The Nares Strait thread
Post by: oren on February 09, 2015, 11:07:28 PM
This thread is, well, WOW! Rewinding the whole arch, interesting trick of mother nature. I wonder what happens next, can't see the arch placing itself right back where it was.
Title: Re: The Nares Strait thread
Post by: Jim Hunt on February 10, 2015, 04:15:35 PM
PolarView makes this far too easy! Here's a more complete image from yesterday evening (UTC)
Title: Re: The Nares Strait thread
Post by: Wipneus on February 12, 2015, 09:07:16 AM
Kennedy, the reverse ice motion extends nearly to the top of the Strait.
Title: Re: The Nares Strait thread
Post by: Neven on February 12, 2015, 11:19:26 AM
I posted about this on the ASIB yesterday: Erase and rewind (http://neven1.typepad.com/blog/2015/02/erase-and-rewind.html).

So, what happens now? Will all of that mobile ice firmly refreeze into place as soon as the wind dies down?
Title: Re: The Nares Strait thread
Post by: Jim Hunt on February 12, 2015, 12:28:01 PM
Will all of that mobile ice firmly refreeze into place as soon as the wind dies down?

Some further movement is revealed by this Sentinel 1A image from February 11th:
Title: Re: The Nares Strait thread
Post by: johnm33 on February 12, 2015, 04:13:32 PM
Right now [16:12] on http://earth.nullschool.net/#current/wind/surface/level/orthographic=-0.48,86.69,1024 (http://earth.nullschool.net/#current/wind/surface/level/orthographic=-0.48,86.69,1024) we have winds blowing directly out of both ends the strait. If that doesn't keep it open nothing will.
Title: Re: The Nares Strait thread
Post by: solartim27 on February 12, 2015, 07:22:41 PM
Right now [16:12] on http://earth.nullschool.net/#current/wind/surface/level/orthographic=-0.48,86.69,1024 (http://earth.nullschool.net/#current/wind/surface/level/orthographic=-0.48,86.69,1024) we have winds blowing directly out of both ends the strait. If that doesn't keep it open nothing will.

Except that it's 5 - 10 knots on the edges, 0 - 5 in the strait.  Next big wind event has slowed down to Sunday from Saturday.  Not much will happen until then.
http://www.windfinder.com/weather-maps/forecast/greenland#4/81.43/-68.99 (http://www.windfinder.com/weather-maps/forecast/greenland#4/81.43/-68.99)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on February 12, 2015, 07:45:51 PM
Comparing Sentinel 02-09 and 02-11 images, ice moved 'upstream' across the entire length of Nares Strait except for the north 10 or 20 km (north Robeson Channel) where it didn't move.  This slow motion could allow local ice to form a continuous sheet and stop the ice for the season (one giant bridge?).  From a couple of sources, winds along Nares Strait appear fairly weak and generally from the south (S, SE or SW) right now. 

I'm not, however, convinced that Nares ice export has ended for the season.
Title: Re: The Nares Strait thread
Post by: Susan Anderson on February 12, 2015, 08:57:35 PM
Thanks everyone for all the images.  Fascinating.  I'm getting some input about how ice loss and breakup since at least 2007 made this possible, that it used to be over 100 feet thick and last much longer.
Title: Re: The Nares Strait thread
Post by: viddaloo on February 12, 2015, 09:14:12 PM
Interesting point, Susan! Comparisons of the Nares 2015 season to 2007 would be welcome from the folks in the know (I believe we even have people who've been there and done research?).

Could 2015 be the biggest Nares Strait season in a 100 years, for instance?
Title: Re: The Nares Strait thread
Post by: Susan Anderson on February 13, 2015, 02:59:12 AM
I'm an observer without anything like the expertise I find here.  But I got permission to include my friend's comment which is more detailed:

"Back in about 2007 that strait was frozen solid all winter long and didn't rid itself of the ice blocking it until May or June. People simp!y forget how thick the ice used to be. Some of the land fast ice shelves attached to Ellesmere were over 120 feet thick. They all broke off and disappeared. There are places up there where the ice covered the sea surface for more than 14000 years. It's all gone."
Title: Re: The Nares Strait thread
Post by: wili on February 13, 2015, 04:36:47 AM
SA, I'm a big fan of yours from RC. Please stick around and lend your perspective (and that of any friends or strangers...)!
Title: Re: The Nares Strait thread
Post by: Neven on February 13, 2015, 08:57:18 AM
I'm an observer without anything like the expertise I find here.  But I got permission to include my friend's comment which is more detailed:

"Back in about 2007 that strait was frozen solid all winter long and didn't rid itself of the ice blocking it until May or June. People simp!y forget how thick the ice used to be. Some of the land fast ice shelves attached to Ellesmere were over 120 feet thick. They all broke off and disappeared. There are places up there where the ice covered the sea surface for more than 14000 years. It's all gone."

Indeed. If I remember correctly, this is the thing that convinces Judith Curry that what is happening in the Arctic, isn't all natural.
Title: Re: The Nares Strait thread
Post by: Jim Hunt on February 13, 2015, 11:01:32 AM
I'm sure this has been mentioned before, but from Kwok et. al. 2010:

http://onlinelibrary.wiley.com/doi/10.1029/2009GL041872/full (http://onlinelibrary.wiley.com/doi/10.1029/2009GL041872/full)

Quote
In 2007, ice arches failed to form. This resulted in the highest outflow of Arctic sea ice in the 13-year record between 1997 and 2009. The 2007 area and volume outflows of 87 × 103 km2 and 254 km3 are more than twice their 13-year means. This contributes to the recent loss of the thick, multiyear Arctic sea ice and represents ∼10% of our estimates of the mean ice export at Fram Strait.
Title: Re: The Nares Strait thread
Post by: nukefix on February 13, 2015, 04:40:19 PM
Nice new cracks visible today

http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SDH_20150213T124909_4135_N_1.final.jpg (http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SDH_20150213T124909_4135_N_1.final.jpg)
Title: Re: The Nares Strait thread
Post by: viddaloo on February 13, 2015, 06:14:02 PM
Quote
The 2007 area and volume outflows of 87 × 103 km2 and 254 km3 are more than twice their 13-year means.

Thanks, Jim! Any chance of getting such figures for 2015, or rather before 2015 is history?
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on February 13, 2015, 06:40:28 PM
Thanks, nukefix.  Ice in northern Baffin Bay moved up to 18 km between Sentinel 02-11 and 02-12 Kane Basin images.  Ice in Smith Sound has moved about 10 km and some ice in southern Kane Basin (just 'above' the most 'upstream' crack) has moved maybe 1 km.  All this movement is southward.

We'll get to see how sturdy the newly formed ice sheets are.  Will they hold?  Will they shatter?
Title: Re: The Nares Strait thread
Post by: Espen on February 13, 2015, 08:43:25 PM
The water is getting sticky around Nares and weird? (Feb 11 and 13):
Title: Re: The Nares Strait thread
Post by: Susan Anderson on February 13, 2015, 08:59:30 PM
Thanks Wili and Neven. I'm around most days, just don't always weigh in.  Currently I can't comment on the main thread, so will trespass here, not entirely OT.  My specialty, if you could call it that, is visual inspection of global circulation shown in water vapor animations and observation of the connections in weather patterns.  My home Boston has been in the news lately, and I have friends abroad and am interested in the whole planet.  Our weather bombs have been huge and when they get to the Atlantic they head north.  Tenney got me looking at the streams that go straight north for a long distance, and we've had those in the north Atlantic for weeks now, very unusual.  I can't help but think the push of heat north is part of this phenomenon.

My skills are not up to displaying this (the setup is dreamy, it's just me), and it changes with time, but this is some of what I'm talking about.  It's similar in the Pacific, but Alaska makes a kind of armpit that redirects the flow differently.

http://synoptic.envsci.rutgers.edu/site/sat/sat.php?sat=nhem&url=../imgs/wv_nhem_anim.gif (http://synoptic.envsci.rutgers.edu/site/sat/sat.php?sat=nhem&url=../imgs/wv_nhem_anim.gif)

Another friend who consults for meteorologists has a nice simple way of putting it, US centric because of the context:

"The mushroom form is actually a sort of vortex which is probably the most efficient energy dissipater know in Nature!  The picture also highlights the extraordinary warmth in both Atlantic and Pacific that is a major factor in setting up the jet stream pattern that we're seeing with abnormal cold over eastern North American and abnormal warmth out west."
Title: Re: The Nares Strait thread
Post by: Wipneus on February 14, 2015, 08:56:24 AM
At the northern entrance to the Nares Strait (and in the Lincoln Sea) the ice stands absolutely still. In the middle it moves enough to make two narrow cracks, one above and one below Hall Basin.

(click to animate)
Title: Re: The Nares Strait thread
Post by: Espen on February 14, 2015, 09:10:36 AM
Wipneus, it is getting sticky now?
Title: Re: The Nares Strait thread
Post by: Wipneus on February 14, 2015, 09:27:03 AM
It is nearly windless, ice still cracks as the ice is thin. I would call this a delicate balance that won't last but can develop several ways.
Title: Re: The Nares Strait thread
Post by: Shared Humanity on February 14, 2015, 03:25:53 PM
Thanks Wili and Neven. I'm around most days, just don't always weigh in.  Currently I can't comment on the main thread, so will trespass here, not entirely OT.  My specialty, if you could call it that, is visual inspection of global circulation shown in water vapor animations and observation of the connections in weather patterns.  My home Boston has been in the news lately, and I have friends abroad and am interested in the whole planet.  Our weather bombs have been huge and when they get to the Atlantic they head north.  Tenney got me looking at the streams that go straight north for a long distance, and we've had those in the north Atlantic for weeks now, very unusual.  I can't help but think the push of heat north is part of this phenomenon.

My skills are not up to displaying this (the setup is dreamy, it's just me), and it changes with time, but this is some of what I'm talking about.  It's similar in the Pacific, but Alaska makes a kind of armpit that redirects the flow differently.

http://synoptic.envsci.rutgers.edu/site/sat/sat.php?sat=nhem&url=../imgs/wv_nhem_anim.gif (http://synoptic.envsci.rutgers.edu/site/sat/sat.php?sat=nhem&url=../imgs/wv_nhem_anim.gif)

Another friend who consults for meteorologists has a nice simple way of putting it, US centric because of the context:

"The mushroom form is actually a sort of vortex which is probably the most efficient energy dissipater know in Nature!  The picture also highlights the extraordinary warmth in both Atlantic and Pacific that is a major factor in setting up the jet stream pattern that we're seeing with abnormal cold over eastern North American and abnormal warmth out west."

That mushroom cloud over the North Atlantic (if that is the area you are referring to) reminds me of the way a pot of water boils as the heated water near the bottom of the pan rises.
Title: Re: The Nares Strait thread
Post by: johnm33 on February 14, 2015, 08:21:30 PM
With nothing entering from the north the current with a little wind assist is beggining to clear the south.  http://www.polarview.aq/images/106_S1jpgsmall/S1A_EW_GRDM_1SDH_20150214T115204_99B4_N_1.jpg (http://www.polarview.aq/images/106_S1jpgsmall/S1A_EW_GRDM_1SDH_20150214T115204_99B4_N_1.jpg)
Title: Re: The Nares Strait thread
Post by: Wipneus on February 15, 2015, 08:11:25 AM
The Kane animation.
Title: Re: The Nares Strait thread
Post by: crandles on February 15, 2015, 11:18:57 AM
Will the question mark arch hold - that is the question.
Title: Re: The Nares Strait thread
Post by: Jim Hunt on February 15, 2015, 12:45:47 PM
Will the question mark arch hold - that is the question.

A close up from yesterday evening (UTC) via Polarview (http://www.polarview.aq/arctic). So far so good?
Title: Re: The Nares Strait thread
Post by: Wipneus on February 16, 2015, 08:12:37 AM
Kennedy, ice is un-gluing at some places.

(click to animate)
Title: Re: The Nares Strait thread
Post by: solartim27 on February 16, 2015, 08:25:25 AM
Kennedy moved a little with the latest wind, as did Lincoln, but I don't think it got as strong as forecast.  The Question Mark holds firm in Kane.  Nothing showing up for at least another week, giving plenty of time for more freezing, wind will actually be out of the south.  I think export at Nares is done for a while. 

Now Fram on the other hand is about to get a beating, might be time to give that thread a bump.

http://ocean.dmi.dk/arctic/kennedy.uk.php (http://ocean.dmi.dk/arctic/kennedy.uk.php)

http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150215s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150215s01a.ASAR.jpg)

http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150214s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150214s01a.ASAR.jpg)
Title: Re: The Nares Strait thread
Post by: johnm33 on February 16, 2015, 11:37:19 AM
Taking a look at http://www.woksat.info/etcxb15/xb15-1203-e-grn-n.html (http://www.woksat.info/etcxb15/xb15-1203-e-grn-n.html) I thought even if it clears it'll clog up in baffin, but http://earth.nullschool.net/#2015/02/17/0900Z/wind/surface/level/orthographic=-24.75,76.36,2048 (http://earth.nullschool.net/#2015/02/17/0900Z/wind/surface/level/orthographic=-24.75,76.36,2048)  +24hr. gives the winds reversing so nothing[ice] will be coming down the strait and with the new moon almost upon us everything will get broken up by wind forced tides, the changed winds enhance clearance of baffin. So poised for breakout in 2-3 days.
Title: Re: The Nares Strait thread
Post by: solartim27 on February 17, 2015, 01:27:42 AM
The tip of the Question Mark came loose, maybe it's not so stable.  Daylight will return to the area in about 2 weeks, how exciting.

The real action is over at Fram though.
http://www.windfinder.com/weather-maps/forecast/greenland#3/78.94/-28.30 (http://www.windfinder.com/weather-maps/forecast/greenland#3/78.94/-28.30)
Title: Re: The Nares Strait thread
Post by: Wipneus on February 17, 2015, 08:21:25 AM
Not (yet) in the public archive or that of DMI, but in PolarView's: an asymmetric arch develops at the begin of Nares.
Title: Re: The Nares Strait thread
Post by: A-Team on February 17, 2015, 10:29:04 AM
Are they breaking new ground here with Sentinel or in serving satellite data images -- what new ground would that be?

Distributing data seems like an afterthought; they're just now roughing out untested concepts for getting data to end users, with heavy dependence on beta testing by unpaid anonymous individuals outside the billion euro program -- yet what aspect could not have by debugged, tested with synthetic data, put on web in final form the day of the launch?

Excuse me, but this is the 6,601 satellite launched to date (3,600 remain in orbit, 1,000 operational). Surely these issues were all worked out by the late 1960's.

Arpanet was put out to bid in 1968. FTP internet servers date to 16 April 1971.

Photoshop was introduced in 1988, 27 years ago. Adobe released thirteen versions prior to the disastrous Oct 2003 introduction of Creative Suite branding. In February 2013 Adobe donated the source code of the 1990 1.0.1 version of Photoshop to the Computer History Museum.

Prefer to work with numeric pixel arrays? Microsoft first released Excel for the Mac on 30 Sept 1985. (No Excel 1.0 for DOS or Windows.)
Title: Re: The Nares Strait thread
Post by: epiphyte on February 17, 2015, 07:07:29 PM

Excuse me, but this is the 6,601 satellite launched to date (3,600 remain in orbit, 1,000 operational). Surely these issues were all worked out by the late 1960's.


I'm pretty sure that the network bandwidth, storage density and compute power required to ingest raw SAR sensor data across a big chunk of the planet and turn it onto pretty pictures did not exist anywhere outside of the three-letter gov't agencies until after the turn of the century.

Just for starters the raw data is downloaded over X-band/optical 520Mbit/s links, to a wide network of ground stations and (not yet) relay satellites. at a rate of 2.4 compressed TBytes /day.

Definitely not your grandpa's internet ;)
Title: Re: The Nares Strait thread
Post by: viddaloo on February 17, 2015, 07:33:10 PM
Excellent questions and answers, A–Team and epiphyte! Really brilliant and something to learn from. My cyberpunk Johnny Mnemonic follow–up question would be if none of these satellites can be said to 'fry' the ice with their radar and other beams of observation? In quantum physics the observer very physically impacts the observed object, so if the sats do not fry ice themselves, I'm sure it can be said that the industrial culture making sats possible does?
Title: Re: The Nares Strait thread
Post by: Wipneus on February 18, 2015, 06:33:25 AM
Arch in Kane:

(click to animate)
Title: Re: The Nares Strait thread
Post by: Wipneus on February 18, 2015, 06:34:23 AM
And in the Lincoln Sea:
Title: Re: The Nares Strait thread
Post by: solartim27 on February 18, 2015, 07:52:40 AM
It looks to me that wind direction will be a major factor for this years melt.  I can't find very good overlaps on Polar View for the Fram area, but here is a look at what just 7 hours of wind did on the 15th to the northwest of Svalbard, the scenes shift over, but the larger cracks overlap.  I'll cross post this over in the Fram thread.
Title: Re: The Nares Strait thread
Post by: nukefix on February 18, 2015, 08:07:56 AM
Excellent questions and answers, A–Team and epiphyte! Really brilliant and something to learn from. My cyberpunk Johnny Mnemonic follow–up question would be if none of these satellites can be said to 'fry' the ice with their radar and other beams of observation?
The power of the radar is 4kW (about four times the power of a standard household microwave-oven) and the energy is spread over tens of square kilometers from an orbital height of 700km...
Title: Re: The Nares Strait thread
Post by: Wipneus on February 20, 2015, 07:32:12 AM
No Sentinel images yet. The UH sea ice concentration animated map based on Jaxa's AMSR2 instrument seems to indicate the upper arch had a partial cave-in, but still holds.
Title: Re: The Nares Strait thread
Post by: jdallen on February 21, 2015, 07:23:11 AM
Excellent questions and answers, A–Team and epiphyte! Really brilliant and something to learn from. My cyberpunk Johnny Mnemonic follow–up question would be if none of these satellites can be said to 'fry' the ice with their radar and other beams of observation?
The power of the radar is 4kW (about four times the power of a standard household microwave-oven) and the energy is spread over tens of square kilometers from an orbital height of 700km...

... In short, providing less heat to the ice than a house-hold infra-red space heater in Cleveland would provide to someone shivering in Boston if aimed in the right direction.
Title: Re: The Nares Strait thread
Post by: viddaloo on February 21, 2015, 07:37:50 AM
... In short, providing less heat to the ice than a house-hold infra-red space heater in Cleveland would provide to someone shivering in Boston if aimed in the right direction.

And as I said, in quantum physics the observer very physically impacts the observed object, so if the sats do not fry ice themselves, I'm sure it can be said that the industrial culture making sats possible does. In any case, the ice is toast.
Title: Re: The Nares Strait thread
Post by: Wipneus on February 22, 2015, 08:37:54 AM
Sequence centered on the Kennedy Channel. The upper arch is no more, ice is covering all open water.

(click to animate)
Title: Re: The Nares Strait thread
Post by: viddaloo on February 23, 2015, 12:35:29 AM
The upper arch is no more, ice is covering all open water.

Guys, I'm not too sure about this so–called Kane bridge either. I sure as hell wouldn't walk it. I'm waiting for a more recent Sentinel shot to post a comparison with this Feb 21 shot.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fd22d7v2y1t140g.cloudfront.net%2Fm_13630770_YbxFR4nyCHcY.jpg&hash=801f05700b71ceacc4630247d257d8ac)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on February 23, 2015, 03:33:52 AM
Comparing the 02-21 and 02-17 Sentinel images, a crack formed across the northernmost end of Kane Basin.  It appears the ice 'north' of the crack has moved generally northward about 1 km, leaving the Kane Basin ice 'frozen in place'.  Ice movement near the southern end of Kennedy Channel, however, wasn't just northward; some chunks have moved about despite it being an apparent frozen melange.
Title: Re: The Nares Strait thread
Post by: Sonia on February 23, 2015, 06:14:16 AM
Sunrise at Hans Island.
Title: Re: The Nares Strait thread
Post by: Wipneus on February 23, 2015, 08:06:22 AM
Caving-in continues from the west...
Title: Re: The Nares Strait thread
Post by: solartim27 on February 24, 2015, 06:38:01 PM
Supposed to have a brief spurt of 20+ knot winds later today and Wednesday, may see some action, but there's not much after that.  Fram wind direction continues to favor export.
Title: Re: The Nares Strait thread
Post by: icefest on February 24, 2015, 09:27:47 PM
Sunrise at Hans Island.

Whats the unit for the insolation?
Title: Re: The Nares Strait thread
Post by: viddaloo on February 25, 2015, 02:32:33 AM
Not exactly an ideal comparison, but it's what I got. What you can see is very little development over these 3 days: It's a solid ice bridge. I'd cross it to get free beer or a shipment of coffee.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fd22d7v2y1t140g.cloudfront.net%2Fm_13635490_5OP5lNm3yrAo.png&hash=2cb6477fd3614e3a4f119aad2949c759)
Title: Re: The Nares Strait thread
Post by: Wipneus on February 25, 2015, 03:48:21 PM
Only some compacting movement in the upper half of the channel. Today it is 30-40 km/h winds all down the Nares Strait, according to earth.nullschool.net, that should be a first real test of the robustness of the current blockade.

(click to animate)
Title: Re: The Nares Strait thread
Post by: johnm33 on February 25, 2015, 07:42:20 PM
snapshot from woksat showing movement in the south
 (https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2Fgff67%2F4bccbdb6b4.jpg&hash=b4c56107d91fe924346d4c8d9b5a19c6)
Title: Re: The Nares Strait thread
Post by: Wipneus on February 26, 2015, 06:32:57 AM
The arch in the Kane seems to be holding. With weaker winds today, it will likely to be there a bit longer.

(click the picture)
Title: Re: The Nares Strait thread
Post by: Espen on February 26, 2015, 10:00:46 PM
The arch in the Kane seems to be holding. With weaker winds today, it will likely to be there a bit longer.

(click the picture)

The arch is growing southwards.
Title: Re: The Nares Strait thread
Post by: solartim27 on February 28, 2015, 09:38:24 PM
Daylight images of Nares are almost here.  Anyone know whats going on with Sentinel and Polar View?
Title: Re: The Nares Strait thread
Post by: johnm33 on March 01, 2015, 02:12:41 AM
Daylight images of Nares are almost here.  Anyone know whats going on with Sentinel and Polar View?

No but here's a snapshot from woksat
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2Fgh6lX%2Fde4722b752.jpg&hash=7dde4e804e423583e8a95590992bb8e4)
which looks more recent than polarview and local conditions courtesy nullschool
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2Fgh7RF%2F97d20ce6f2.jpg&hash=9fa9c8f374b627c16d86a8270872796f)
That badly sprung arch looks like it's there to stay[?] but the rapidly forming ice in the south seems to break up and head south almost as soon as it freezes.
Title: Re: The Nares Strait thread
Post by: Wipneus on March 04, 2015, 08:10:17 AM
Arch is holding, not a crack visible apart from a bad image stitch.
Title: Re: The Nares Strait thread
Post by: johnm33 on March 04, 2015, 10:20:20 AM
With winds as they are and increasing over the next 24hr both at the south end of Fram and all the way down Baffin there's just a slim chance the full moon low tides will induce some cracks. (https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2FglPRb%2F2a27d6f518.jpg&hash=e7aa2995498c60c5ef25ba31aad46354)
ot take a look at the energy of the water emerging from below the ice in the lower reaches of the bay especially the turmoil on the coast south of the entrance to Hudson, courtesy worldview/ march 02
http://map2.vis.earthdata.nasa.gov/imagegen/index.php?TIME=2015061&extent=-1407947.5023126,-4186084.1522005,676916.4976874,-2297828.1522005&epsg=3413&layers=MODIS_Terra_CorrectedReflectance_TrueColor,Coastlines&opacities=1,1&worldfile=false&format=image/jpeg&width=8144&height=7376 (http://map2.vis.earthdata.nasa.gov/imagegen/index.php?TIME=2015061&extent=-1407947.5023126,-4186084.1522005,676916.4976874,-2297828.1522005&epsg=3413&layers=MODIS_Terra_CorrectedReflectance_TrueColor,Coastlines&opacities=1,1&worldfile=false&format=image/jpeg&width=8144&height=7376)
Title: Re: The Nares Strait thread
Post by: Wipneus on March 04, 2015, 10:44:27 AM
Someone alerted me (thanks!) by email that the sun has risen over the arch, see  MODIS image  (http://lance-modis.eosdis.nasa.gov/imagery/subsets/?subset=Arctic_r03c02.2015061.terra.250m).


Title: Re: The Nares Strait thread
Post by: Jim Hunt on March 04, 2015, 11:59:50 AM
I actually prefer to use Worldview, which allows easy comparison with previous years:

http://GreatWhiteCon.info/resources/arctic-sea-ice-images/winter-201415-images/#Nares (http://GreatWhiteCon.info/resources/arctic-sea-ice-images/winter-201415-images/#Nares)

Here's 2014, on March 5th and a bit cloudy:

Title: Re: The Nares Strait thread
Post by: ghoti on March 04, 2015, 06:18:35 PM
And we are only a few days from Worldview showing the Fram in in daylight! We'll be able to compare the ice flowing out the Fram to the ice stuck behind the Nares arch.
Title: Re: The Nares Strait thread
Post by: solartim27 on March 04, 2015, 07:41:38 PM
We can see Fram on Modis.  Here's 3/4 versus 2/20
http://lance-modis.eosdis.nasa.gov/imagery/subsets/?mosaic=Arctic (http://lance-modis.eosdis.nasa.gov/imagery/subsets/?mosaic=Arctic)
Title: Re: The Nares Strait thread
Post by: Wipneus on March 06, 2015, 06:33:43 AM
Arch looks like it is getting stronger.

(click to animate)
Title: Re: The Nares Strait thread
Post by: Wipneus on March 07, 2015, 08:46:45 AM
At the top the ice has not realized that the way is blocked.
Title: Re: The Nares Strait thread
Post by: Wipneus on March 09, 2015, 11:50:40 AM
Sonia's ice floe/berg stuck in the middle of the Kane Basin as seen by Landsat 8 on March 7. The shadows are about 4 pixels or,  @ 15m/pixel, 60m long. With sun elevation of only 5.17o I estimate the height of the central portion a bit over 5 m. So I guess it is not an ice berg after all.

(image resampled at 7.5m/pix)   
Title: Re: The Nares Strait thread
Post by: Wipneus on March 09, 2015, 11:57:18 AM
The Kane is speckled with objects like these. Here the shadows are about four times as long. In my opinion these are ice bergs.

(image scaled as above)
Title: Re: The Nares Strait thread
Post by: Sonia on March 09, 2015, 12:09:10 PM
That's my conclusion too from looking at recent MODIS images.  The objects with long shadows are concentrated at the Humbolt and extend out from there in long filaments.  I think a contrast stretch would show this well but I don't have time to mess with it at the moment.
Title: Re: The Nares Strait thread
Post by: LRC1962 on March 11, 2015, 01:25:25 PM
According to this (http://earth.nullschool.net/#current/wind/surface/level/overlay=mean_sea_level_pressure/orthographic=302.24,72.58,1122) the storm on the south east corner of Greenland seems to pulling wind through the strait. Is it strong enough to make an impact on the blockage?
Title: Re: The Nares Strait thread
Post by: viddaloo on March 21, 2015, 04:46:34 PM
What happened to this thread?!

Very high winds (http://earth.nullschool.net/#current/wind/surface/level/orthographic=-24.77,76.14,2048) in the Nares right now:

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fd22d7v2y1t140g.cloudfront.net%2Fm_13686375_HyvDIxSIkxAV.png&hash=e15c1e33fce3f6a4e9d03ea2874c54fb)
Title: Re: The Nares Strait thread
Post by: johnm33 on March 21, 2015, 06:28:08 PM
"What happened to this thread?!"
 It's frozen, even the exceptional tides following the eclipse are unlikely to shift the compressed ice thats rammed into the strait and consolidated these last 5[?] weeks. but you never know...
Title: Re: The Nares Strait thread
Post by: Wipneus on April 19, 2015, 09:32:32 AM
Some movement in the Lincoln Sea.
Title: Re: The Nares Strait thread
Post by: Neven on April 19, 2015, 10:39:21 AM
OMG, is Nares opening up on the other side this year?  ;) ;D
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on April 19, 2015, 02:40:38 PM
That ice wants out, and if Nares refuses to open up, by gosh, it'll find another way :D
Title: Re: The Nares Strait thread
Post by: crandles on April 20, 2015, 11:26:56 PM
question mark arch broken?

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Flance-modis.eosdis.nasa.gov%2Fimagery%2Fsubsets%2FArctic_r03c02%2F2015110%2FArctic_r03c02.2015110.terra.1km.jpg&hash=b5dc0853d595e4ce7d17cb0938784fc4)
Title: Re: The Nares Strait thread
Post by: Neven on April 21, 2015, 12:06:16 AM
question mark arch broken?

The question mark, yes, but the arch looks pretty solid now. At least, to me. Well spotted, BTW.
Title: Re: The Nares Strait thread
Post by: Wipneus on April 21, 2015, 08:14:11 AM
More ice decides not wait for the Strait to re-open.
Title: Re: The Nares Strait thread
Post by: johnm33 on April 21, 2015, 11:09:31 AM
At some point it had to fill, the ice has been compressed into it for 7? weeks, but still the torrent beneath drives through.
 (https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2FhlxeB%2Ffd871ce20e.jpg&hash=496528861d95be92cca4e0db1be30460)
 from DMI
Looking at the area of Crandles image on worldview, for the last 3 weeks, both Lancaster and Jones have only fresh ice, and as soon as the temps. rise will clear rapidly
Title: Re: The Nares Strait thread
Post by: crandles on April 22, 2015, 09:04:37 PM
Despite
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKane%2F20150420TERR.jpg&hash=136d6e4a02cd2e114cbbf3369a2272c3)
on 20th

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKane%2F20150422s01a.ASAR.jpg&hash=a4fa1da5c4b920092713d3e246f8bef7)
on 22nd

So looks like I was wrong. Question mark still in place. So pieces breaking off south of question mark.
Title: Re: The Nares Strait thread
Post by: solartim27 on May 07, 2015, 07:51:52 AM
Still holding strong, some wind coming through Saturday, might be time to move.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 17, 2015, 02:32:29 AM
I don't expect it will come to pass in May, by the US Navy's CICE ice concentration maps (http://www7320.nrlssc.navy.mil/hycomARC/navo/arcticicen_nowcast_anim30d.gif) forecast less than 100% ice in Nares Strait this next week (down to 30%!). (DMI's Sentinel 1 or MODIS (http://ocean.dmi.dk/arctic/kane.uk.php) images don't suggest anything to me.)

It think this is just to get us excited!  You know, throw the dogs some bones, and they'll be happy for hours.

Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 22, 2015, 04:32:00 PM
The little polynya at the NE end of Kane Basin (Cape Jackson) is opening up, per TERRA and AQUA images on the DMI website (http://ocean.dmi.dk/arctic/kane.uk.php).  The ice bridge should break within ... 2 months.   :P
Title: Re: The Nares Strait thread
Post by: Siffy on May 24, 2015, 08:43:51 PM
Another little chunk has broken off in the strait.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fi60.tinypic.com%2F16iwnkx.jpg&hash=9764eff78c6e6710df67f961094fbf2c)
Title: Re: The Nares Strait thread
Post by: Jim Hunt on May 24, 2015, 09:02:34 PM
Whilst this is how the northern end looks at present:
Title: Re: The Nares Strait thread
Post by: Sonia on May 25, 2015, 12:14:06 AM
It's fascinating to me that ice in a large part of the Lincoln Sea has stayed mobile all winter.  It would refreeze for a little bit, then winds would change and the polynyas would open right back up.  The ice is all raring to go as soon as the Nares opens.
Title: Re: The Nares Strait thread
Post by: epiphyte on May 25, 2015, 05:00:14 AM
@siffy - looking at it from this perspective, the chunk that just broke off seems to be losing coherence and starting to melt almost immediately - as though it was insubstantial even before it separated from the arch. If the rest of it is as diaphanous as that part appears to have been, I'd hazard it won't last very long.
Title: Re: The Nares Strait thread
Post by: solartim27 on May 25, 2015, 06:59:52 AM
Here's the Sentinel shot from Polarview, seeing some motion on the bottom of the question mark.  Could open up pretty quick.  Click to animate.
http://www.polarview.aq/images/106_S1jpgsmall/S1A_EW_GRDM_1SDH_20150524T121703_5638_N_1.jpg (http://www.polarview.aq/images/106_S1jpgsmall/S1A_EW_GRDM_1SDH_20150524T121703_5638_N_1.jpg)
Title: Re: The Nares Strait thread
Post by: solartim27 on May 26, 2015, 06:19:28 AM
Looks like some strongish winds have stripped some small bits off the bottom of the curve.  I see no other motion flipping between images.
http://ocean.dmi.dk/arctic/image_container.php (http://ocean.dmi.dk/arctic/image_container.php)
Title: Re: The Nares Strait thread
Post by: solartim27 on June 05, 2015, 08:13:55 PM
Some more slight movement at the Greenland side of the arch in Kane
http://www.polarview.aq/images/106_S1jpgsmall/S1A_EW_GRDM_1SDH_20150605T121704_D869_N_1.jpg (http://www.polarview.aq/images/106_S1jpgsmall/S1A_EW_GRDM_1SDH_20150605T121704_D869_N_1.jpg)
Title: Re: The Nares Strait thread
Post by: Sonia on June 08, 2015, 01:18:48 AM
Hans Island weather station reading above freezing for the first time this year I think.
Title: Re: The Nares Strait thread
Post by: Wipneus on June 08, 2015, 08:19:30 AM
The ice in the Lincoln Bay is stirring again.
Title: Re: The Nares Strait thread
Post by: solartim27 on June 10, 2015, 06:10:00 PM
Strong winds from the south, are those waves in the bay?
Title: Re: The Nares Strait thread
Post by: johnm33 on June 10, 2015, 07:08:03 PM
It's getting quite warm, for the time of year,
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2FijIvy%2F4bb4c67ad8.jpg&hash=8438cca56db649615fc813a607874e61)
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2FijIrR%2Fb17b26236a.jpg&hash=9f830e1afaf8b16b1fddb26ea5008baf)
so maybe some movement as the new moon approaches.
Title: Re: The Nares Strait thread
Post by: icefest on June 11, 2015, 02:09:45 PM
Strong winds from the south, are those waves in the bay?

Unless they are interference I doubt they're waves. That wavelength is greater than 50m, and the pattern isn't diffractive.

I suspect they're more likely to be clouds or similar,   
Title: Re: The Nares Strait thread
Post by: Neven on June 11, 2015, 02:30:11 PM
The day we're able to see waves on satellite images, we need to make for the hills. Make that mountains.  ;)
Title: Re: The Nares Strait thread
Post by: nukefix on June 11, 2015, 02:45:54 PM
Strong winds from the south, are those waves in the bay?
They look more like atmospheric rolls that modulate the small-scale roughness of the sea surface.
Title: Re: The Nares Strait thread
Post by: solartim27 on June 13, 2015, 07:55:27 AM
Breakout, must have ben the high surf
Title: Re: The Nares Strait thread
Post by: solartim27 on June 13, 2015, 08:39:55 PM
Jun 13 vs Jun 11
Title: Re: The Nares Strait thread
Post by: johnm33 on June 16, 2015, 11:28:14 PM
In the last 2 posts by solartim27 there's been a schism across the bay http://www.polarview.aq/arctic (http://www.polarview.aq/arctic) which has melted away, we have winds at 40k plus http://earth.nullschool.net/#current/wind/surface/level/overlay=temp/orthographic=0.39,78.15,512 (http://earth.nullschool.net/#current/wind/surface/level/overlay=temp/orthographic=0.39,78.15,512) blowing south a new moon what are the chances of breakout at low tide?
Title: Re: The Nares Strait thread
Post by: werther on June 16, 2015, 11:47:24 PM
Break-out? I'd say good chance. Fracturing is now visible on MODIS across the Strait between Kane Basin and the peterman-Fjord.
Title: Re: The Nares Strait thread
Post by: johnm33 on June 17, 2015, 11:24:34 AM
Courtesy of DMI
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2Fis3Ul%2Fb5287c2da7.jpg&hash=642e91a19ab0764c9efa854c32a4305d)
Title: Re: The Nares Strait thread
Post by: A-Team on June 17, 2015, 02:44:25 PM
When the region of interest is white-on-white (as with these Modis images), the contrast can sometimes be usefully expanded to make fuller use of monitor dynamic range. This is especially suited to fractures.

One fast way to do this is mask out the rocks, normalize the remaining contrast to 0,255, and then equalize the (global) histogram. This would take about 15 seconds of twiddling in Gimp or similar.

A better way of bringing out features is to do this locally. For that, look for a menu command called CLAHE in your image processing software. A round-trip to ImageJ2 (free, platform-independent) takes around 45 seconds on this size image.

This time of year, Landsat provides very nice coverage of Nares (via http://earthexplorer.usgs.gov/ (http://earthexplorer.usgs.gov/)). The LandsatLook natural color is a small fast file with quite good resolution; the region of the two islands is shown in the snippet below from LC80292482015167LGN00. Much of Nares lies within this single image.
Title: Re: The Nares Strait thread
Post by: johnm33 on June 17, 2015, 09:12:03 PM
Seemed kind of rude not to give it a shot
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2Fiszje%2Fd02683aec3.jpg&hash=a4698ac69a6b50f76ae688c2e0bbc9ca)
some way to go yet
Title: Re: The Nares Strait thread
Post by: johnm33 on June 19, 2015, 07:08:08 PM
Cracks nearing the arch, from DMI
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2FiuZ8v%2F0b58c2b9bc.jpg&hash=ed6155914724663c4f6379ab581db9d5)
Title: Re: The Nares Strait thread
Post by: solartim27 on June 19, 2015, 07:22:34 PM
How can this not have collapsed yet?!?!  Oh, I get it, this year it's going to break up going to the north with the wind.  Here's the Worldview pic, you can identify the individual bergy bits seen in Sentinel now, so there must be no more snow cover.

Vergents thickness map from the melting season thread has a rather thick patch at Kane basin.
Title: Re: The Nares Strait thread
Post by: Laurent on June 20, 2015, 07:44:37 PM
The ice is collapsing inside Nares strait.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 20, 2015, 11:09:23 PM
20-06-2015 [Sentinel-1] from DMI (http://ocean.dmi.dk/arctic/kane.uk.php):  I find this very interesting that the ice bridge in Kane Basin is holding but the ice 'behind' it is cracking/breaking up.  Soon (I'm sure) a crack will break the bridge.  The ice, it appears, took my joke seriously (some time back) that 'the ice wants out of Nares Strait and if it has to get out through the Lincloln Sea, then so be it'!
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKane%2F20150620s01a.ASAR.jpg&hash=4b032a26d92c692df80785745e5ed15d)
Title: Re: The Nares Strait thread
Post by: johnm33 on June 21, 2015, 12:32:11 PM
Courtesy DMI + Gimp, can't see this holding on much longer,
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2Fix3t1%2F857b36021a.jpg&hash=72dab470b61cc049702b1203c0747d58)
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2Fix3vL%2Fefceb15dbe.jpg&hash=39e2b0656837ecefabfc5c46ed342d64)
Title: Re: The Nares Strait thread
Post by: oren on June 21, 2015, 03:08:20 PM
Last year the breakup of the arch began on June 20th or 21st. The year before it happened on July 3rd. In both years when cracks appeared it conincided with the arch beginning to collapse. So judging by recent history it's supposed to give in any day now.
Title: Re: The Nares Strait thread
Post by: A-Team on June 21, 2015, 07:01:04 PM
Lower left corner does not look real solid ...
Title: Re: The Nares Strait thread
Post by: johnm33 on June 21, 2015, 09:13:39 PM
Latest Kane from DMI movement continues
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2Fixv4E%2F3fdad8fa3c.jpg&hash=284abb1d67afe35e1e93bbbd3df00be3)
Title: Re: The Nares Strait thread
Post by: johnm33 on June 22, 2015, 11:47:31 PM
The ice in the bay has changed rain?
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2FiyRxu%2F66aba477e1.jpg&hash=61a714c9fe8bcbec0d6d30bb664bb7ba)
the cracks grow
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2FiyRDD%2F73ee5f1936.jpg&hash=92f02caaf8f911cc23cd38fbe1d98ce3)
I still have no idea when this breaks free a day? a week? a month?
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 23, 2015, 02:42:56 AM
I detect no movement of ice between the "Kane Basin Crack" and the edge of the Kane Basin ice bridge (comparing June 22 and June 20 Sentinel images (http://ocean.dmi.dk/arctic/kane.uk.php) - both are shown 'above').  I only see ice movement 'north' of the KBC.  On the June 22 image, I might be seeing a crack that is quozi-perpendicular to the KBC heading toward the ice bridge along the southern edge of the channel (along the 'obvious' texture change in the ice, and well away from the shore); I do not detect any lateral movement across this crack.

Interesting that in the June 21 Sentinel image, the KBC appears to have closed up.  (Obviously, it opened up again.) 
Title: Re: The Nares Strait thread
Post by: Jim Hunt on June 24, 2015, 01:10:04 AM
Meanwhile further North:

http://1.usa.gov/1RuyUJa (http://1.usa.gov/1RuyUJa)
Title: Re: The Nares Strait thread
Post by: johnm33 on June 24, 2015, 05:15:02 PM
There's quite a lot of melt going on next to the bay http://beta.dmi.dk/en/groenland/maalinger/greenland-ice-sheet-surface-mass-budget/ (http://beta.dmi.dk/en/groenland/maalinger/greenland-ice-sheet-surface-mass-budget/)
and some sort of water feature has appeared, whether melt, rain or a quickly frozen lead?
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2FiB3bf%2Fa4fc769318.jpg&hash=8a5d9187f75964bc48f9e019744b22c0)
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2FiB366%2F4b7a7696b6.jpg&hash=2152a1c15d9c7942dd5deb6d605d2621)
Title: Re: The Nares Strait thread
Post by: Jim Hunt on June 26, 2015, 12:10:07 AM
More movement:
Title: Re: The Nares Strait thread
Post by: johnm33 on June 26, 2015, 11:13:04 AM
This is the original
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKane%2F20150625AQUA.jpg&hash=909977396cb3ee823f88d62df67dc00c)
this the lightly gimped
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2FiDd3n%2F9df61485be.jpg&hash=a8f20ac34cf9a18b81bd04ab4f8ac173)
it's hard not to see that evaporation/cloud formation taking place at the crack which indicates relatively warm waters surging south, lots of bottom melt allowing more compaction, cracks giving traction and a low soon to pass over. I don't think it'll [arch] last past 2nd july,  perhaps even the whole archipelago will open up.
Title: Re: The Nares Strait thread
Post by: Shared Humanity on June 26, 2015, 04:59:38 PM
I'm not sure that is  moisture as a result of this large lead but if it is, we are looking at low cloud or dense fog. This would be caused by warm air coming into contact with cold water.
Title: Re: The Nares Strait thread
Post by: johnm33 on June 26, 2015, 06:50:10 PM
I'm not sure that is  moisture as a result of this large lead but if it is, we are looking at low cloud or dense fog. This would be caused by warm air coming into contact with cold water.
You're probably right i just checked and the winds were mostly blowing north.
Title: Re: The Nares Strait thread
Post by: solartim27 on July 01, 2015, 10:00:18 PM
Full moon high tide, with lots of cracks, and strong winds to the north, and still no motion at the edge.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 01, 2015, 10:18:56 PM
Comparing today's Sentinel image with the one from June 29 on DMI (http://ocean.dmi.dk/arctic/kane.uk.php), I see what may be two new thin cracks much closer to the ice bridge than the 'obvious' crack that  crosses the basin diagonally.  The two cracks (if that is what they are) parallel the long dimension of the basin and are closer to the ice bridge than the 'obvious crack' and 'point' toward the thin end of the 'obvious crack'.

I would not be surprised if the bridge breaks in the next day or two.  Caveat: my predictions are lousy!
Title: Re: The Nares Strait thread
Post by: solartim27 on July 02, 2015, 01:28:33 AM
I was dead set for the last new moon, glad I didn't say so.
Title: Re: The Nares Strait thread
Post by: Sonia on July 02, 2015, 02:01:18 AM
I've been watching the moon phases go by, but the wind has been so persistently from the south!  The wind reversed for two days last week.  I held my breath as the mobile ice all shifted south to press against the remaining fast ice, but it all held, both in the Kane and the Hall.  I'm not good with weather but it looks like this south wind will get rather stiff in about two days.  I'll be watching closely then.  Even if all all becomes mobile though it won't mean much for export as long as the wind stays from the south.  The export was interesting last year because the reduced pressure seemed to allow the Lincoln ice to become mobile.  Amazingly it's still sloshing around, but currently with nowhere to go.
Title: Re: The Nares Strait thread
Post by: johnm33 on July 02, 2015, 09:29:58 AM
This sentinel shot from Dmi shows a significant break just south of the arch, some signs of movement on the Ellesmere coast and the change in the surface near Humbolt suggests melt which has allowed compaction and hence the crack further up.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKane%2F20150701s01a.ASAR.jpg&hash=518f26f913de001f8c23da6c391cb339)
Title: Re: The Nares Strait thread
Post by: oren on July 02, 2015, 10:02:31 AM
This sentinel shot from Dmi shows a significant break just south of the arch, some signs of movement on the Ellesmere coast and the change in the surface near Humbolt suggests melt which has allowed compaction and hence the crack further up.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKane%2F20150701s01a.ASAR.jpg&hash=518f26f913de001f8c23da6c391cb339)

I missed that break near the arch at first glance. Seems like the beginning of the collapse process.
Title: Re: The Nares Strait thread
Post by: johnm33 on July 02, 2015, 01:47:37 PM
The original http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150701TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150701TERR.jpg) shows a crack of sorts along the coast/fast ice to the west, and extensive cracks elsewhere, my attempt to enhance
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2FiKyzV%2Fe476820c0e.jpg&hash=ca8abc5576dcd88dba9bbb62a0c2aaef)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 02, 2015, 04:54:00 PM
A close-up of the crack you can readily see crossing most of Kane Basin is attached.  I think this is within the dark rectangle in johnm33's DMI image from earlier today.  See the fine crack that goes from the lower right corner to 2/3rds up the left side of the image.  This image is from July 1 Polar View (http://www.polarview.aq/arctic) imagery: specifically here (http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SDH_20150701T115951_3664_N_1.final.jpg).

The cracks I thought I saw yesterday that would be perpendicular to this new fine crack do not show up at all.  Was I wishful thinking?
Title: Re: The Nares Strait thread
Post by: johnm33 on July 02, 2015, 07:30:21 PM
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2FiKRj9%2F9bd4235eed.jpg&hash=ba65738c64301d9fcbb3805b48845254)
Couple of pieces adrift
Title: Re: The Nares Strait thread
Post by: oren on July 03, 2015, 11:25:52 PM
Another large piece of fast ice broke off south of the first piece

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKane%2F20150703AQUA.jpg&hash=04c6cfe26c62b968daaa4ed3e3726847)
Title: Re: The Nares Strait thread
Post by: johnm33 on July 04, 2015, 11:13:47 AM
There's a clearer shot here, http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150703s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150703s01a.ASAR.jpg)
 
Title: Re: The Nares Strait thread
Post by: oren on July 04, 2015, 01:04:24 PM
I could swear that one was much clearer when I posted it... guess they updated the contents
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 04, 2015, 02:32:12 PM
On the detailed Polar View from yeterday (here (http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SDH_20150703T213058_6F06_N_1.final.jpg)), I see some new [I believe] cracking near the Canadian side of Kane Basin not terribly far from the ice bridge [I don't call it an arch because it isn't center-of-the-building 'arch' shaped - it is sort of a flying buttress shaped arch, though.]  See attached.  The captured image shows some water [edit: or is that thin ice?] on the left, shore at the top, and cracks on the right.
Title: Re: The Nares Strait thread
Post by: johnm33 on July 04, 2015, 07:51:16 PM
This is the original, http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150704s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150704s01a.ASAR.jpg) and tweaked version. Some movement on the Greenland side.
 (https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2FiN914%2Fdb5ed673b4.jpg&hash=bda8108c288bb0cfc36f061f8ffb822b)
these two are early and late shots from yesterday, judging by the shadows, if it's that sunny today I can't see it lasting much longer, but given my record best take a pinch of salt with that.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2FiN9kk%2Fc5e98255cb.jpg&hash=3bdaa304fc56eef14a7eb7c513dee3ac)
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2FiN9m7%2Fe30641d3ff.jpg&hash=5945a40676dfea8fe38a927d05cd147f)
Title: Re: The Nares Strait thread
Post by: oren on July 06, 2015, 05:31:32 PM
There's been another breakup of fast ice, this time on the oppsite site of the strait.
I can't believe the arch is still intact... it really should go soon  >:(

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKane%2F20150705TERR.jpg&hash=bd4773166193ca9f6e15104a0a9d3f12)
Title: Re: The Nares Strait thread
Post by: johnm33 on July 06, 2015, 09:39:49 PM
The top end is trashed
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKennedy%2F20150705TERR.jpg&hash=bcee041fd68c23046925c1a5d8ae16ac)
not nearly as beautiful [as Orens] but all the damage shows
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKane%2F20150706s01a.ASAR.jpg&hash=a710efed8553433fac87c1b2e697a52b)
and this shows the local melt on humbolt
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fbeta.dmi.dk%2Fuploads%2Ftx_dmidatastore%2Fwebservice%2Fb%2Fm%2Fs%2Fy%2Fa%2Ftodaysmb.png&hash=7d8c2b0ef22897a371fd0bad1d80e5ad)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 07, 2015, 02:48:36 PM
Either I'm 'seeing things' (that aren't there) or I'm seeing things (that are there).  Looking at two high resolution Polar View images here (http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SDH_20150706T120759_2AEC_N_1.final.jpg) and especially here (http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SDH_20150706T215538_5414_N_1.final.jpg), both from July 6, 2015, I see several tiny cracks zigzagging across the bridge.  One is in the 'fast ice' near the Canadian shore. One nicks the southern end of the fast ice on the Canadian side of the bridge.  Others are part of a general breakup of the bridge.  The 2nd image is more recent and is very dark (and only covers a small part of the bridge on the Canadian side) and I can only 'see things' when looking at the screen from an angle (putting my face near the computer screen edge and looking askance), but it seems to show wider cracks.

Is today the day?
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 07, 2015, 04:46:23 PM
Yesterday's DMI composite view of Kane Basin shows a discrepancy in the bridge edge associated with an obvious seam between original images.  Is this offset due to movement between the time/date of the two images? (see johnm33's 2nd image above)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 07, 2015, 08:18:11 PM
Comparing the July 4 and July 7 Sentinel images from DMI (by putting the two images in different windows and matching the position of land features), it appears the ice bridge is bulging a km or so in the middle of Kane Basin. 

(I cannot download the latest Polar View detail image.)

Also, most of the fast ice near the Greenland side of the ice arch has fallen off, but this wasn't structural.
Title: Re: The Nares Strait thread
Post by: johnm33 on July 07, 2015, 08:32:11 PM
The latest Polar View
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fwww.polarview.aq%2Fimages%2F106_S1jpgsmall%2FS1A_EW_GRDM_1SDH_20150707T124854_BF2F_N_1.jpg&hash=75928a6926d46e672dd7c8f3516d61cc)
I'm thinking this break up of the top is caused by the tidal race this shows the relative speeds
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fwww.esr.org%2FAOTIM%2Ffig3_full.png&hash=3dccdfc892d45bc8c2840eca7bf69acd)
I'm looking for a close up.
Title: Re: The Nares Strait thread
Post by: Jim Hunt on July 07, 2015, 09:29:26 PM
The latest MODIS:

http://GreatWhiteCon.info/resources/arctic-sea-ice-images/summer-2015-images/#Nares (http://GreatWhiteCon.info/resources/arctic-sea-ice-images/summer-2015-images/#Nares)
Title: Re: The Nares Strait thread
Post by: johnm33 on July 07, 2015, 11:16:44 PM
I can thoroughly recommend a quick scan of the first few pages of this topic if like me your desperate for the breakthrough.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 08, 2015, 05:05:37 PM
I could open the full resolution JPG Polar View image (http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SDH_20150707T205803_4AD7_N_1.final.jpg) this morning.  A few of the cracks or groups of cracks are circled on the attached image of the Canadian side of the ice bridge (Elsmere Island on top, open water in lower left corner). Other fainter (probable) cracks are also discernible.
Title: Re: The Nares Strait thread
Post by: Espen on July 08, 2015, 07:44:49 PM
My unqualified guess:We are only hours away from the collapse of the Nares Arch.
Title: Re: The Nares Strait thread
Post by: Andreas Muenchow on July 08, 2015, 10:30:17 PM
I think it already collapsed several days ago, just a little slower than usually. The moment the shape changed, it did not have the structural integrity anymore to hold it together. The ice must be fairly mushy, too, given the very high surface air temperatures we saw the last couple of days on Hans Island.

Lets hope all this ice flushes out at a faster clip as it does right now. The Swedish icebreaker Oden is on her way to pick up a group of people at Thule Air Force Base on July-29 to sail on for a large experiment this year focused on the glacial and geological history of Petermann Fjord and Glacier as well as Nares Strait. I feel very lucky indeed to be given the opportunity to be on the ship.

There will be a flurry of activities in Nares Strait and Petermann Fjord this summer with massive amounts of new data from below the surface, invisible to remote sensing. Lots of outreach and sharing planned by multiple people at multiple institutions in multiple countries working on multiple ships.
Title: Re: The Nares Strait thread
Post by: Jim Hunt on July 08, 2015, 11:09:34 PM
Lots of outreach and sharing planned by multiple people at multiple institutions in multiple countries working on multiple ships.

Excellent news Andreas! Thanks for the heads up.
Title: Re: The Nares Strait thread
Post by: A-Team on July 09, 2015, 06:30:34 PM
That's great news. Andreas ... were you not slated to look at ocean/shelf interactions at 79N or is that a leg of this expedition? From the many publications of the PIs, it sounds like formanifera-based Holocene water temperatures, seismic profiles, underwater moraines coring, maybe keel drags.

Right now, the Oden is going nowhere fast according to this tracking service ... are they waiting to see if Nares will clear out better? Petermann fjord is still in the early stages of clearing to the rifting front. The ship is rated for 2 m thick ice.

The Renland ice cap expedition, completed to bedrock in just 4 weeks, did a most excellent job of daily blogging. I think the answer is having a PI do the write-up, not a summer intern back in the office.

It's worth looking at how and what they provided, even some real-time logging data like ECM profiles. Renland is the first non-brittle Holocene core for Greenland. It is said to be a proxy for ice discharge down the Fram.

Very informative: http://recap.nbi.ku.dk/field_diaries/2015/ (http://recap.nbi.ku.dk/field_diaries/2015/)

Here is a very detailed account of how Jason Box landed in hot water over a comment made on a previous Oden voyage. (Denmark is also the home of the notorious denier Bjorn Lomborg.)

http://www.esquire.com/news-politics/a36228/ballad-of-the-sad-climatologists-0815/ (http://www.esquire.com/news-politics/a36228/ballad-of-the-sad-climatologists-0815/)

Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 09, 2015, 06:58:45 PM
Greenland side of ice bridge giving way (see attached image - part of Polar View (http://www.polarview.aq/arctic)'s JPG full resolution (http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SDH_20150709T123326_C88D_N_1.final.jpg))(Greenland [with bluish 'mask'] at bottom of image, open water at left)

[Question: can anyone tell me how to have attachments show?]
Title: Re: The Nares Strait thread
Post by: Neven on July 09, 2015, 07:01:12 PM
Greenland side of ice bridge giving way (see attached image - part of Polar View (http://www.polarview.aq/arctic)'sJPG full resolution (http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SDH_20150709T123326_C88D_N_1.final.jpg))(Greenland [with bluish 'mask'] at bottom of image, open water at left)

[Question: can anyone tell me how to have attachments show?]

Tor, I think the problem is that it's a PDF file.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 09, 2015, 07:11:37 PM
Greenland side of ice bridge giving way (see attached image - part of Polar View (http://www.polarview.aq/arctic)'s JPG full resolution (http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SDH_20150709T123326_C88D_N_1.final.jpg))(Greenland [with bluish 'mask'] at bottom of image, open water at left) ...
Attached JPG is same as previous PDF. (Thanks, Neven;  now I know how to have an attachment show.)
Title: Re: The Nares Strait thread
Post by: A-Team on July 09, 2015, 08:14:26 PM
Here is a composite of two PolarView Sentinels for today, 9th July T=123226, mostly from S1A_EW_GRDM_1SDH_20150709T123226_9D1C_N_1.
Title: Re: The Nares Strait thread
Post by: Andreas Muenchow on July 09, 2015, 08:28:55 PM
The Renland ice cap expedition, completed to bedrock in just 4 weeks, did a most excellent job of daily blogging. I think the answer is having a PI do the write-up, not a summer intern back in the office.

It's worth looking at how and what they provided, even some real-time logging data like ECM profiles. Renland is the first non-brittle Holocene core for Greenland. It is said to be a proxy for ice discharge down the Fram.

Very informative: http://recap.nbi.ku.dk/field_diaries/2015/ (http://recap.nbi.ku.dk/field_diaries/2015/)
I could not agree more, but at $50K/day and 21 hours/day awake, should the PI focus on efficient use of the ship to support science or should s/he spent time blogging? The above site is very well done indeed ... I suspect we may be more chaotic in our presentations, as we are diverse group in disciplinary background, gender, age, culture, politics, style, and personal temperaments. Also, at 81 N we do not have the same connectivity that people farther south have. Iridium is charged by the second ... Think 1984-type dial-up modems at 1200 baud. Resources are always finite and the budget always shows where your priorities are. Compromise and balance are much harder in practice than in theory ;-)

As for the ice in Nares Strait, yes, I'd like it to be out of the way. The last thing an icebreaker wants to do is breaking ice. It is slow, gobbles fuel like crazy, and takes valuable resources away from science or, as we oceanographer call it, "wire time." It is always smarter to work with nature, not against it. Winds, tides, and currents are somewhat predictable and often the longer way is faster and more productive. Furthermore, multiple disciplines working together becomes a strength: one group's signal is another group's noise and vice versa.
Title: Re: The Nares Strait thread
Post by: oren on July 09, 2015, 11:19:24 PM
Greenland side of ice bridge giving way (see attached image - part of Polar View (http://www.polarview.aq/arctic)'s JPG full resolution (http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SDH_20150709T123326_C88D_N_1.final.jpg))(Greenland [with bluish 'mask'] at bottom of image, open water at left)

Yes, I believe the ice bridge has finally given up. The whole thing moved forward a little bit, leaving that big crack behind. This is a later date than the past few years, probably correlated to the ice in Baffin staying much longer this year.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 09, 2015, 11:59:40 PM
When early Hudson Bay melt put 2015 ahead of most (all?) other years, I recall someone (somewhere) wonder if extra early snow protected the ice from the grueling cold eastern North America experienced last NH winter.  I don't know what caused the early start, but I suspect there wasn't 'extra early snow' and that most of Hudson Bay and Baffin Bay were actually thicker than typical (compared to recent years), and the consequent extra ice is what has delayed their mid-season melt-out.  This may have also caused the Kane Basin ice bridge to be thicker and therefore more resilient.  I wonder if the ice bridge being across the 'middle' of Kane Basin (rather than across Smith Sound) means that water flowing under it is slower and less abrasive?
Title: Re: The Nares Strait thread
Post by: Neven on July 10, 2015, 08:59:05 AM
When early Hudson Bay melt put 2015 ahead of most (all?) other years, I recall someone (somewhere) wonder if extra early snow protected the ice from the grueling cold eastern North America experienced last NH winter.

I think that was me. I was surprised that Hudson Bay was melting so fast, given the megacold during winter in the NE USA, and speculated that massive snow might have insulated the ice, and during the first 'heat wave' this snow turned into melt ponds causing the fragile ice below to quickly disintegrate. But it seems it was the wind?

On-topic: Nares arch finally giving way, eh?
Title: Re: The Nares Strait thread
Post by: johnm33 on July 10, 2015, 09:39:29 AM
This'll do it
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKane%2F20150709AQUA.jpg&hash=07e670c4f2e3f122ba46e51bbfe70963)
added
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2FiTQv9%2F09ea147f32.jpg&hash=b7a2f88c5f29410baf586dbc0c7e77f1)
It looks like solid ice by Humbolt to me, I'm guessing that'll need a nudge or the tides of the approaching new moon to shift it.
Title: Re: The Nares Strait thread
Post by: johnm33 on July 10, 2015, 10:38:40 AM
I haven't mastered animations yet but clicking through these three windows shows the recent movement up at Kennedy
http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150709TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150709TERR.jpg)
http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150709AQUA.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150709AQUA.jpg)
http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150708TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150708TERR.jpg)
Title: Re: The Nares Strait thread
Post by: Shared Humanity on July 11, 2015, 03:03:14 AM
Somebody already called it this but that ice bridge is a flying buttress and all of the stress is where that buttress comes into contact with the coast of Greenland. I think we need to look there for the approaching collapse.
Title: Re: The Nares Strait thread
Post by: A-Team on July 11, 2015, 06:09:43 PM
Quote
no animations yet but clicking through these

Thanks to DMI, it is moderately easy to make these, or at least harvest a time series of imagery from the same satellite. Then the issue becomes clouds, tiling coverage and geometric registration.

Below I took the last 16 Sentinel images for Kennedy view and aligned on Hans Island. This resulted in so-so global consistency in alignment, beyond what image-specific rotations could fix. To keep file size down, the images are rotated CW by 36º so that a crop box can cut out extraneous land. The arch is not included; that would be a separate exercise using Kane view.

Tiling two frames for each day is problematic, though a great project for a hypothetical unpaid summer intern.  Sentinel sees through clouds but the downside is different geometry for each orbit.

Click to view animation ... it did not work out reducing width to 700 pixels. The pause is on July 10th. I'll post a Petermann Glacier cut-out over at that forum.
Title: Re: The Nares Strait thread
Post by: ghoti on July 12, 2015, 07:30:10 PM
Looks like the base of the "flying buttress" blew out today (July 12). Looks like we'll soon be trying to track chunks of ice flowing out the Nares.
Title: Re: The Nares Strait thread
Post by: oren on July 13, 2015, 12:10:26 AM
I put together a crude animation of Kane basin, using daily AQUA images from DMI. It starts from June 20th and goes on until July 12th, with many gaps in between where images had too many clouds.
I think it shows nicely the crumbling of the arch, which was visibly cracked away and started moving on July 9th (the frame with the little extra pause).
To my layman's eye it seems the crumbling happened under pressure from the crushed ice coming from the northeast, and after losing some of the buttressing of the fast ice to the west.

Edit: managed to make it animate at last, see new post below.
Title: Re: The Nares Strait thread
Post by: Laurent on July 13, 2015, 11:12:48 AM
This is not a GIF ? but an image "png".
Follow that video, it should help :
https://www.youtube.com/watch?v=Qn7ubD-aeeU (https://www.youtube.com/watch?v=Qn7ubD-aeeU)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 13, 2015, 02:45:15 PM
Ice bridge is breaking up nicely, finally! (at least at the edges)  :D
From yesterday's MODIS (http://rapidfire.sci.gsfc.nasa.gov/imagery/subsets/?subset=Arctic_r03c02.2015193.terra.250m):
Title: Re: The Nares Strait thread
Post by: Neven on July 13, 2015, 04:07:33 PM
Yup, there she blows. Thanks, Tor.
Title: Re: The Nares Strait thread
Post by: oren on July 13, 2015, 06:41:34 PM
I put together a crude animation of Kane basin, using daily AQUA images from DMI. It starts from June 20th and goes on until July 12th, with many gaps in between where images had too many clouds.
I think it shows nicely the crumbling of the arch, which was visibly cracked away and started moving on July 9th (the frame with the little extra pause).

Click to animate  8)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 13, 2015, 08:15:25 PM
Attached a 40m/pix detail of Sonia's floe or iceberg located in the main stream just outside the Petermann fjord (direction top of this image), data from 2015-01-21. As can be seen the white is part of a bigger and darker floe. ...
(It was later determined to be a floe, not a berg - lack of a long shadow.)

It got caught by the Kane Basin ice bridge.  Can we find it?
(Wipneus' image from January 21, 2015)
Title: Re: The Nares Strait thread
Post by: Andreas T on July 13, 2015, 08:30:46 PM
Thanks for the animation, Oren, it shows nicely how the ice north of the arch is broken up before the arch starts to give way. It is moving back and forth, but what is driving that movement? I seem to remember Andreas Muenchow writing that tides are quite weak there.
Title: Re: The Nares Strait thread
Post by: Neven on July 13, 2015, 09:59:12 PM
Yeah, thanks a lot for the animation, oren. I've adjusted it a bit and used it for a blog post (http://neven1.typepad.com/blog/2015/07/nares-strait-ice-on-the-move.html) on the ASIB.
Title: Re: The Nares Strait thread
Post by: oren on July 13, 2015, 10:53:17 PM
Yeah, thanks a lot for the animation, oren. I've adjusted it a bit and used it for a blog post (http://neven1.typepad.com/blog/2015/07/nares-strait-ice-on-the-move.html) on the ASIB.

Cool!
Title: Re: The Nares Strait thread
Post by: johnm33 on July 13, 2015, 11:40:14 PM
Thanks for the animation, Oren, it shows nicely how the ice north of the arch is broken up before the arch starts to give way. It is moving back and forth, but what is driving that movement? I seem to remember Andreas Muenchow writing that tides are quite weak there.
The tidal range is limited but the tidal race through the narrows is quite fast and the southern flow holds fast to the western/north shore, and is as turbulent as the flow down the east coast of Greenland.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 14, 2015, 09:36:59 PM
Where is Sonia's ice floe hiding?
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 15, 2015, 04:55:21 AM
I wonder how big a floe will get through Smith Sound.  The largest piece of the old ice bridge could thread its way through or it could get broken into pieces.
Title: Re: The Nares Strait thread
Post by: johnm33 on July 15, 2015, 10:58:54 AM
Latest Terra from DMI
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKane%2F20150714TERR.jpg&hash=c9f145e2c5de13a452a1702af49c5d34)
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKennedy%2F20150714TERR.jpg&hash=b424a048d9d27c431ebfc9933a6254a7)
Title: Re: The Nares Strait thread
Post by: johnm33 on July 15, 2015, 03:43:57 PM
Clicking between the two images gives a little insight into tide/wind interplay 13th.
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150713AQUA.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150713AQUA.jpg)
14th. http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150714AQUA.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150714AQUA.jpg)
Title: Re: The Nares Strait thread
Post by: johnm33 on July 17, 2015, 11:32:53 AM
With persistent winds from the south there's been little export, this image sequence ends with the ice breaking up in the fjord opposite Peterman.
http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150713TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150713TERR.jpg)
http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150714TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150714TERR.jpg)
http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150715TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150715TERR.jpg)
http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150715AQUA.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150715AQUA.jpg)
http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150716TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150716TERR.jpg)
Title: Re: The Nares Strait thread
Post by: johnm33 on July 18, 2015, 11:32:26 AM
The winds have shifted, they're now blowing south at about 20kph, the southern end is clouded but this image shows clear signs of the ice moving south again compared to the last of the previous list.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKennedy%2F20150717TERR.jpg&hash=f4fc3c95276e387176b8f8ac054f6a14)
and if you want to click between them- http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150717TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20150717TERR.jpg)
Title: Re: The Nares Strait thread
Post by: Andreas Muenchow on July 18, 2015, 03:28:16 PM
Yes, the winds are now from north to south now, but Hans Island

http://dalriada.sams.ac.uk/aws_hans/ (http://dalriada.sams.ac.uk/aws_hans/)

shows only weak winds at about 2 m/s which comes to 7.2 km/h. This morning's 08:40 MODIS Aqua image

http://lance-modis.eosdis.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2015199084000-2015199084500.250m.jpg (http://lance-modis.eosdis.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2015199084000-2015199084500.250m.jpg)

shows the ice moving from the Greenland coast towards the Ellesmere Island coast in Robeson and Kennedy Channel. Winds cause surface ocean or ice flow at angle to the right of the wind (Coriolis force does this in balance of forces between surface friction and Coriolis). So, let the flushing begin, finally ;-)
Title: Re: The Nares Strait thread
Post by: johnm33 on July 18, 2015, 09:38:15 PM
My bad, I was looking at the southern end of Kane for wind speed
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2Fj3ZSs%2Fd012da9d94.jpg&hash=3a32d6ff28e503b60ed432687116bccd)
Title: Re: The Nares Strait thread
Post by: Andreas Muenchow on July 19, 2015, 01:41:00 AM
@Johnm33:

Nothing wrong with that location; I would have picked it as the most relevant for the flushing of ice out of Nares Strait, too, but how far off the ground are those model winds? Furthermore, how well does the model agree with direct wind observations such as those on Hans Island?
Title: Re: The Nares Strait thread
Post by: johnm33 on July 19, 2015, 11:48:36 AM
This is yesterday at 15:00 close to Hans Island, the wind speed is about double down at southern Kane, same pattern today just slower, so good for flushing.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2Fj4GMZ%2F0ff963d3ca.jpg&hash=32042725c1d84a66921aacb80e247946)
Title: Re: The Nares Strait thread
Post by: Espen on July 19, 2015, 07:45:44 PM
The break up of Nares Strait and Petermann Fjord in progress, but somehow later than I expected, we got to be prepared for Andreas arrival ;):
Title: Re: The Nares Strait thread
Post by: A-Team on July 19, 2015, 08:18:22 PM
Awesome what a difference a day can make ... look how much Petermann opened up in 24 hrs. Let's keep an eye out for calving too, what with buttressing back pressure being so rapidly reduced.

I looked with a high resolution Sentinel pair for where the next break might be ... some possibilities, nothing definitie. Not change yet in the ice sheet's calving front.
Title: Re: The Nares Strait thread
Post by: Andreas T on July 19, 2015, 08:29:07 PM
I am looking forward to images from Oden as it goes up Nares strait. The ice north of it looks like it is ready to be flushed towards it. No large floes which might get stuck.
Title: Re: The Nares Strait thread
Post by: johnm33 on July 20, 2015, 01:54:21 PM
Beneath the clouds the southern end is breaking out, if the winds persist for a few days, and at present they're still blowing to the south [6kph] at the exit to Kane basin, we could see the whole strait flowing.
On the 16th the wind was still holding back the ice
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150716s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150716s01a.ASAR.jpg)
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150717s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150717s01a.ASAR.jpg)
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150718s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150718s01a.ASAR.jpg)
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150719s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150719s01a.ASAR.jpg)
and the top end is just smashed
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKennedy%2F20150719TERR.jpg&hash=ae4e7e6c3cf3ec84fc82d16e0ea5fb58)
Title: Re: The Nares Strait thread
Post by: Espen on July 22, 2015, 08:55:50 PM
There is a crack in the Nares plug:
Title: Re: The Nares Strait thread
Post by: Andreas Muenchow on July 22, 2015, 11:06:58 PM
More than one by now. Also check out the massive upwelling along the Arctic coast of the Canadian Archipelago indicative of strong winds from east to west that move the apparently very loose Arctic sea ice offshore or to the north.

Hans Island winds have been 15 knots (7-8 m/s) for the last 48 hours.

There is also a massive sediment plume coming from a river that traces back to the land-termianting Hidatha (spelling?) Glacier. The river discharges into southern Kane Basin. Hope to write this all up more tidily in my next blog post. Greenland side of Kennedy Channel largely free of ice as the wind causes "upwelling" there (and downwelling off Ellesmere). Ocean dynamics beautifully visualized by the ice as a tracer for surface ocean flow.
Title: Re: The Nares Strait thread
Post by: oren on July 22, 2015, 11:09:10 PM
More than one by now. Also check out the massive upwelling along the Arctic coast of the Canadian Archipelago indicative of strong winds from east to west that move the apparently very loose Arctic sea ice offshore or to the north.

Hans Island winds have been 15 knots (7-8 m/s) for the last 48 hours.

There is also a massive sediment plume coming from a river that traces back to the land-termianting Hidatha (spelling?) Glacier. The river discharges into southern Kane Basin. Hope to write this all up more tidily in my next blog post. Greenland side of Kennedy Channel largely free of ice as the wind causes "upwelling" there (and downwelling off Ellesmere). Ocean dynamics beautifully visualized by the ice as a tracer for surface ocean flow.

Andreas - when you do, please post a link to your blog, I'll be very interested in reading it.
Title: Re: The Nares Strait thread
Post by: Andreas T on July 25, 2015, 11:30:37 AM
I too enjoy reading Andreas M's blog posts, he is a very busy man at the moment so I am taking the liberty of posting a link although I am an entirely different Andreas
http://icyseas.org/ (http://icyseas.org/) you can also find the link quickly in Andreas Muenchows profile or on Neven's blog page.
Title: Re: The Nares Strait thread
Post by: JER on July 26, 2015, 12:17:22 AM
Would anyone please like to take a guess regarding whether it is going to be feasible to travel this route and hopefully get ashore in various places, especially on Baffin and Ellesmere Islands and on Greenland well north of Qaanaaq? http://www.lifeonthinice.org/data/web/20150818_20150906_Itinerary.jpg (http://www.lifeonthinice.org/data/web/20150818_20150906_Itinerary.jpg)

Departing Kangerlussuaq on August 18; traveling the route clockwise; returning to Kangerlussuaq September 6. The vessel is ice-reinforced, but not an ice-breaker.

Cheers,
Jenny
Title: Re: The Nares Strait thread
Post by: JER on July 26, 2015, 12:35:03 AM
Just to be clear, I'm concerned about the coastal regions that are still showing 50-100% ice concentration on the Uni Bremen site.
Title: Re: The Nares Strait thread
Post by: Jim Hunt on July 26, 2015, 02:38:37 AM
Would anyone please like to take a guess regarding whether it is going to be feasible to travel this route and hopefully get ashore in various places, especially on Baffin and Ellesmere Islands and on Greenland well north of Qaanaaq?

Hi Jenny,

Andreas Muenchow (see just above) is in the area in Oden as we speak. Rather than guess, instead hope that he has time to check in here and answer that question! Here's the hashtag, in case that helps:

https://twitter.com/hashtag/Petermann2015

Personally I don't see the ice in Baffin Bay lasting that much longer, but then I've never been further north than Oslo!


Title: Re: The Nares Strait thread
Post by: JER on July 26, 2015, 03:33:31 AM
Thanks, Jim.

I'm also guessing (hoping!) that there will be enough melt along the coast of Baffin Island to get ashore there in some locations. But I'm particularly concerned about the heavy ice hanging on in Kane Basin and in all the bays along the southeast coast of Ellesmere.

Hopefully news from Oden will clarify the situation.
Title: Re: The Nares Strait thread
Post by: Andreas Muenchow on July 26, 2015, 03:46:22 AM
Jer:

You should be fine if you stay on the Greenland side up to Qaanaaq and Smith Sound. It should also be possible to cross over the the Canadian side from there, perhaps visit Grise Fjord, then head south again. I very strongly recommend against going any farther north. The moment you cross Smith Sound and Cape Sabine, there is no way to assure you or your ship will get back out. Many larger ships got crushed, stranded, or blocked at the endtrance to Kane Basin for the last 150 years. Even if it looks good for a day or two because the winds are favorable, the very strong tides, the fickly winds, and the ice shifting fast, this is not something to take lightly, it is not a place to go without lots of resources.

The Arctic is not a place to count on luck. be careful, enjoy your freedom of movement, enjoy your boat gives you. Just don't sink it all by trying to do too much without proper preparation that may take years.
Title: Re: The Nares Strait thread
Post by: Andreas Muenchow on July 26, 2015, 03:50:40 AM
Just to be clear, I'm concerned about the coastal regions that are still showing 50-100% ice concentration on the Uni Bremen site.
While this is a very good site, it is not a good product to navigate by. The resolution is too coarse and not always accurately represing actual ice conditions. You should be looking at LandSat (free) or RadarSat (very expensive) at 30 m resolution to get a feel for what the ice may look like from the ground. There are many resources here on these forums (Sentinel), but Uni Bremen ice maps are NOT a tool to plan an actual sail with, because the pixels are too big.

Edit: I am not on Oden until next wednesday or so. Even this powerful icebreaker will have a very hard time navigate through Kane Basin. It almost appears that more ice enters from the north than exits in in the South,
Title: Re: The Nares Strait thread
Post by: JER on July 26, 2015, 03:58:27 AM
Thanks very much, Andreas -- greatly appreciated!

I'm not responsible for doing the actual planning or navigating; thankfully, there are people far more knowledgeable than I am who are in charge. (I'll be doing photography.) I'm trying to anticipate where we'll likely be able to go and which locations won't be reachable.

Do you think it might be feasible to get farther north than Grise Fjord by late August?

All the best,
Jenny
@LifeOnThinIce

EDIT: "farther north than Grise Fjord" along the coast of Ellesmere.
Title: Re: The Nares Strait thread
Post by: A-Team on July 26, 2015, 05:47:04 AM
This is a particularly problematic year. The ice has backed in again to Petermann fjord, refilling it. Melt lakes on the ice shelf peaked about 3 weeks ago, little is left for steam drilling; and the 35 km of kayakable central drainage never filled.

I would use Sentinel here for ice. It's free and has almost daily coverage at this latitude, see below. There's preview coast-hugging footage at DMI http://ocean.dmi.dk/arctic/morrisjessup.uk.php (http://ocean.dmi.dk/arctic/morrisjessup.uk.php) and high resolution full Baffin coverage at ESA https://scihub.esa.int/dhus/ (https://scihub.esa.int/dhus/)

A leg of the Amundsen just got cancelled, GeoTraces sciences. As I read it, 2-3 commercial supply ships wanted an icebreaker to fulfill fuel contracts with small coastal communities, a non-emergency situation but one that was costing them money to stand off waiting for the ice to clear. They got the government to issue the necessary orders. Nothing else was available as icebreaker because of budget cuts.

Quote
Instead of carrying 40 scientists deep into the Arctic to research climate change, the Amundsen has been temporarily reassigned to break ice for several commercial supply ships.

The Amundsen on Sunday pulled in its scientific probes, did a U-turn in Davis Strait – between Greenland and Nunavut – and headed to the south tip of Baffin Island.

“The Amundsen has never been diverted from science for ice breaking duty in the Arctic according to the Captain,” wrote Dr. Cullen, a University of Victoria researcher whose Geotraces project relates to the impacts of ocean acidification and climate change effects.

He said research projects, some of which took four years to plan, will have to be cancelled. Dr. Cullen said he understood the urgency of helping supply ships, but was disappointed the Coast Guard didn’t have any other vessels available.

Johnny Leclair, the Coast Guard’s acting assistant commissioner for the Central and Arctic Region, said the Amundsen had to be reassigned because of “harsh conditions.”

He said two other Coast Guard vessels in the region weren’t available. The Pierre Radisson is busy helping a fuel tanker trapped in ice in Frobisher Bay and the Terry Fox had to be sent back to port in Newfoundland to resupply after escorting ships through the ice.
http://www.theglobeandmail.com/news/british-columbia/arctic-research-expedition-put-on-hold-after-vessel-diverted-to-break-ice/article25618672/ (http://www.theglobeandmail.com/news/british-columbia/arctic-research-expedition-put-on-hold-after-vessel-diverted-to-break-ice/article25618672/)
Title: Re: The Nares Strait thread
Post by: JER on July 26, 2015, 08:54:35 AM
Thanks a lot, A-Team -- very helpful!

I heard about the Amundsen a couple days ago. Terrible situation for the scientists.
Title: Re: The Nares Strait thread
Post by: Neven on July 26, 2015, 12:03:25 PM
Jenny, if after your journey you want to use the Arctic Sea Ice blog to share images or texts, send me a mail.
Title: Re: The Nares Strait thread
Post by: JER on July 27, 2015, 12:13:33 AM
Great, Neven. Thanks!
Title: Re: The Nares Strait thread
Post by: Andreas T on July 31, 2015, 09:59:39 PM
according to http://www.sailwx.info/shiptrack/shipposition.phtml?call=SMLQ (http://www.sailwx.info/shiptrack/shipposition.phtml?call=SMLQ)
the Oden should be getting near the ice by now.
Title: Re: The Nares Strait thread
Post by: ghoti on July 31, 2015, 10:12:39 PM
According to http://oden.geo.su.se/map/ (http://oden.geo.su.se/map/) their speed has dropped to near 0. They must be in the ice now.
Title: Re: The Nares Strait thread
Post by: A-Team on August 01, 2015, 05:56:35 AM
Quote
speed has dropped to near 0. They must be in the ice now.
Been doing some probing it look like, then backing out and trying somewhere else. Or they may be doing planned science experiments. Red lines are the nominal course in and out. It clears up quite a bit the way they are headed and Petermann is fully accessible.
Title: Re: The Nares Strait thread
Post by: JER on August 01, 2015, 07:56:44 PM
How does one differentiate between cloud-cover and ice on Sentinel images (other than by experience)?
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on August 01, 2015, 11:27:57 PM
Jenny,
Basically, Sentinel sees through clouds.  There are some effects, sometimes, mostly away from the center, and you can get what appear to be shadows or brightening.  I think all the 'white' on the lower left of the above image is bits of ice.  Attached is an enlargement of some of that area.  I wonder if the white 'worm' path on the right side (centered top-to-bottom) is the ship passage.
Title: Re: The Nares Strait thread
Post by: JER on August 02, 2015, 01:30:00 AM
Thanks, Tor. Why is some of the ice whitish/light grey, while some is dark grey/nearly black? Different ice densities or surface characteristics?

"I wonder if the white 'worm' path on the right side (centered top-to-bottom) is the ship passage."

Interesting. Seems to be roughly in the right place.
Title: Re: The Nares Strait thread
Post by: Andreas T on August 02, 2015, 12:47:36 PM
Quote
Why is some of the ice whitish/light grey, while some is dark grey/nearly black? Different ice densities or surface characteristics
I am a learner in that respect myself but what I know so far is that these radar images are basically showing gradients in terrain, you see one side of a mountain as a bright area, the other as a dark area. Which side is bright and which dark depends on orientation of the satellite, the attached images were taken in different orientation. It looks like the mountains are illuminated from the side but of course the "illumination" is produced by the satellite radar.
It doesn't just show largescale sloping gradients it also shows roughness. It picks out crevassing on glaciers and cities in light shades because there are different echoes from the top and bottom of buildings for example close together.
On smaller scales broken up bits of ice also shows up brighter than flat expanses of ice. But old multiyear ice also has a bumpier surface than smoother one year ice. Then there is the question of what surface does the radar "see". The frequencies which it uses are AFAIK reflected differently by snow and ice and water. I think this is what gives those bands on the ice cap seen in the bottom left of the images. Thick snow and firn seems to always appear bright.
An important difference between the 3107 and 0108 images is that the water surface (identifiable from the visible terra image) is also bright in some places in the 3107 image. Rough water surface, waves also give a "bright" response, depending on the orientation of the satellite.
Despite the different times these images were taken there are recogniseable ice floes in all three. How different they can appear shows how much background information is needed to interpret these reliably. Sometimes it is easy to make an educated guess, sometimes not so much. Best I can do at the moment is look carefully at many images and detect patterns.
A good place for compareable visible and radar images is
 http://ocean.dmi.dk/arctic/kane.uk.php (http://ocean.dmi.dk/arctic/kane.uk.php)
sorry I haven't taken the time to size and crop the images to match, I guess as a photographer you'll see that anyway, Jenny
Title: Re: The Nares Strait thread
Post by: JER on August 02, 2015, 11:59:53 PM
Thanks, Andreas T. Very interesting and helpful.
Title: Re: The Nares Strait thread
Post by: ghoti on August 21, 2015, 08:09:57 PM
I've always wondered about the thickness of the ice in the Lincoln Sea given the various modeled sources of thickness maps. Now the Oden is in the Nares and is seeing chunks of ice flowing in from the north. They posted a photo.

https://twitter.com/SjoV_isbrytning/status/634730153927680000

The estimate from the tweeter is that the pieces of ice they are seeing are 4-5m thick flowing in from the north.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on September 03, 2015, 05:47:33 PM
I just compared MODIS images of Sept. 1 (http://rapidfire.sci.gsfc.nasa.gov/imagery/subsets/?subset=Arctic_r03c03.2015244.terra.250m) and Sept. 2 (http://rapidfire.sci.gsfc.nasa.gov/imagery/subsets/?subset=Arctic_r03c03.2015245.terra.250m).  The biggest floe in Robeson Channel (just south of Lincoln Sea) went southward about 17 km between those dates.  The largest floe behind in went about 33 km and a floe ahead of it went about 28 km.  Some floes opposite Petermann Fjord moved over 60 km (as best I can tell). [Incidentally, the narrowest part of Petermann Fjord is about 15 km wide for scale.  When I write “southward”, I usually mean “southwestward” as Nares Strait is really aligned Northeast-Southwest.]  Floes in Lincoln Sea moved generally 5 to 15 km westward or toward Nares Strait (i.e., westward, southwestward or southward) except for floes west of the strait’s mouth that mostly moved a little westward.
Title: Re: The Nares Strait thread
Post by: TerryM on September 03, 2015, 09:12:08 PM
Tor
Did it seem to you that Nares was first of all late to break, then when it was open to flow, most of the ice just remained in place?
Hopefully Dr. Muenchow's ride home will be uneventful.
Terry
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on September 03, 2015, 09:50:47 PM
Tor
Did it seem to you that Nares was first of all late to break, then when it was open to flow, most of the ice just remained in place?
Hopefully Dr. Muenchow's ride home will be uneventful.
Terry
Yes, the ice, even after the ice bridge broke, mostly sat around waiting for the moment nobody was looking before heading south.  The winds, of course, were mostly from the south at the time.

I recall last early NH (that's Northern Hemisphere, not New Hampshire, where I once lived) winter when ice 'flew' south.  It appears it is migration season again.  (Sorry for, not exactly anthropomorphizing, but avianomorphizing, the poor innocent ice.)
Title: Re: The Nares Strait thread
Post by: cats on September 04, 2015, 12:42:24 AM
Some interesting observations from the Oden as it headed back down the Nares Strait -
"The irony of all of this is that the big icebergs and floes streaming southward out of the Arctic Ocean and blocking the strait may be an indicator of Arctic warming. Although icebergs are not unknown here, those who have been on past expeditions did not report so many. Normally they tend to stay put up in the Arctic, but we think maybe the ice there has loosened up enough that the bergs are free to drift southward. We are not sure of this; will have to check satellite images and commentaries from ice tracking programs when we get home."
Full blog post at https://petermannsglacialhistory.wordpress.com/updates-from-co-chief-scientist-alan-mix/august-29-80-degrees-north/

Title: Re: The Nares Strait thread
Post by: Jim Hunt on September 04, 2015, 08:10:59 AM
Maybe the ice there has loosened up enough that the bergs are free to drift southward.

A bit like this do you suppose?

http://GreatWhiteCon.info/resources/arctic-sea-ice-images/summer-2015-images/#Nares (http://GreatWhiteCon.info/resources/arctic-sea-ice-images/summer-2015-images/#Nares)
Title: Re: The Nares Strait thread
Post by: Wipneus on November 22, 2015, 07:34:57 AM
A big float in the Lincoln Bay is attempting to block the Nares Strait (or break in the attempt).
Seen in the last frame, strong winds from the south (77 km/h according to nullschool) blow the float away for now.
Title: Re: The Nares Strait thread
Post by: Wipneus on December 11, 2015, 12:28:06 PM
Arches are forming at both ends of the Nares.

(The image of Kane needs a click)
Title: Re: The Nares Strait thread
Post by: Neven on December 11, 2015, 07:29:49 PM
And so the game begins yet again.  8)
Title: Re: The Nares Strait thread
Post by: oren on December 13, 2015, 12:27:05 AM
Actually it feels rather early. Let's see if it holds.
Title: Re: The Nares Strait thread
Post by: Wipneus on December 29, 2015, 02:15:47 PM
The two arches are still there.
Title: Re: The Nares Strait thread
Post by: Shared Humanity on February 29, 2016, 02:56:50 PM
I thought I would pull this thread up to the top by commenting that, in my very inexpert opinion, the Nares will be open for business early this year. The heat anomalies for western Greenland have been simply ridiculous all winter and I think the arches will collapse very early.
Title: Re: The Nares Strait thread
Post by: Jim Hunt on March 04, 2016, 01:26:27 PM
The first "visual" images of the southern arch are now available via Worldview:

http://GreatWhiteCon.info/resources/arctic-sea-ice-images/winter-2015-16-images/#Nares (http://GreatWhiteCon.info/resources/arctic-sea-ice-images/winter-2015-16-images/#Nares)
Title: Re: The Nares Strait thread
Post by: solartim27 on April 12, 2016, 08:24:38 AM
A bit broke off yesterday.
Title: Re: The Nares Strait thread
Post by: A-Team on April 12, 2016, 05:36:04 PM
Faster, easier, better to use EarthExplorer preview image? Neat cloud pattern. The 15 m band 8 Landsat is also quite remarkable in its detail. Is that some sort of melt fringe or wetted ice?
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on April 18, 2016, 06:51:20 PM
A-Team:  The Landsat images are awesome!
I'm pretty sure the rim on the south edge of the bridge is 'fast ice' (frozen sea water), whereas the bridge 'proper' is composed almost entirely of pieces of older and thicker Arctic Ocean floes frozen together. 

Anybody know what happened to DMI (http://ocean.dmi.dk/arctic/kane.uk.php)'s  TERRA images?  The last image is dated April 5, 2016.  (There are daily images from March 1, 2016 to April 5, 2016 available through the link.)
Title: Re: The Nares Strait thread
Post by: A-Team on April 18, 2016, 11:16:35 PM
Quote
Anybody know what happened to DMI's TERRA images?  The last image is dated April 5, 2016

I'm seeing Terra images are provided up to 12 Apr 16 for Pituffik, Lincoln and Morris Jesup but as you say not past the 5th for Kennedy, Kane and Quunaaq. Even the 12th is bordering on dated here on the 18th.

Quote
I'm pretty sure the rim on the south edge of the bridge is 'fast ice' (frozen sea water), whereas the bridge 'proper' is composed almost entirely of pieces of older and thicker Arctic Ocean floes frozen together.

Have you looked at a GRD IW class Sentinel 1A scene of the rim and bridge? It seems like salt water and salty ice should appear black in radar because of ion dipoles where as frozen freshwater ice would be reflective. The download hub is here:

https://scihub.copernicus.eu/dhus/#/home [broken down again despite 'root cause' fixed yet again yesterday!]
Title: Re: The Nares Strait thread
Post by: Sonia on April 19, 2016, 05:33:25 AM
Have you looked at a GRD IW class Sentinel 1A scene of the rim and bridge? It seems like salt water and salty ice should appear black in radar because of ion dipoles where as frozen freshwater ice would be reflective
Thank you for that explanation.  It's a tip that helps a lot with image interpreation!
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on April 20, 2016, 07:23:02 PM
...
Anybody know what happened to DMI (http://ocean.dmi.dk/arctic/kane.uk.php)'s  TERRA images?  The last image is dated April 5, 2016.  (There are daily images from March 1, 2016 to April 5, 2016 available through the link.)

DMI (http://ocean.dmi.dk/arctic/kane.uk.php)'s TERRA images are back! At, least, there are images dated the 18th and 19th. (Everything is basically still covered with snow, except for the open polynya below the ice bridge.)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 03, 2016, 07:50:00 PM
The little polynya at the northern end of Kane Basin just off Cape Jackson is back.  It forms every year long before the ice bridge collapses.  Attached is a piece of the latest DMI Terra (http://ocean.dmi.dk/arctic/kane.uk.php) image showing just the northern end of Kane Basin with Cape Jackson and the polynya circled.
Title: Re: The Nares Strait thread
Post by: Tealight on May 03, 2016, 11:20:28 PM
Interesting. Are these formed by rocks, grounded icebergs or something else? I'm not sure because the Nares Strait is littered with icebergs and its hard to tell the difference.

Attached is a S2A image of the polyna from 30th April. Click to see full resolution.
Title: Re: The Nares Strait thread
Post by: johnm33 on May 04, 2016, 09:40:02 AM
The polynya, I think there are two strong contenders for the cause, my preferred option is that the west greenland slope current has been drawn north by tidal forces and it's kinetic energy and heat are being dissipated beneath this fast ice, the other is that Barents water  has been forced to the top of Nares by the huge gyration and movement taking place in Beaufort, and this forms coherent overturning currents which flow down the east side of Nares where again the kinetic and heat content erode the fast ice from below. The normal flow through Nares appears to be Arctic waters which due to their inertia are forced to flow on the west side of the strait.
You can see on this Nullschool anim. gyres forming off the west coast of Greenland, and to the south of Nares [though they have been more pronounced than this recently] and if you click back a couple of days you'll see the anomoly in the south changes considerably.
http://earth.nullschool.net/#2016/05/03/0000Z/ocean/surface/currents/overlay=sea_surface_temp_anomaly/orthographic=-58.78,67.53,1336/loc=-56.730,55.527 (http://earth.nullschool.net/#2016/05/03/0000Z/ocean/surface/currents/overlay=sea_surface_temp_anomaly/orthographic=-58.78,67.53,1336/loc=-56.730,55.527)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 04, 2016, 04:33:38 PM
The polynya, I think there are two strong contenders for the cause,  ...
Thanks!  I sorta figured it was something like what you describe. 

Edit:  P.S. - thanks for the detailed image, Tealight!
Title: Re: The Nares Strait thread
Post by: bbr2314 on May 07, 2016, 09:08:09 AM
If DMI's model is correct it looks like Nares may break within next few days.
Title: Re: The Nares Strait thread
Post by: oren on May 07, 2016, 10:23:54 AM
Looking at recent images of Kane Basin, I would put it at zero probability. This is not the proper time of year, and everything looks whole and healthy there.
Title: Re: The Nares Strait thread
Post by: johnm33 on May 07, 2016, 10:46:19 AM
A chunk has broken off on the Ellesmere side, http://ocean.dmi.dk/arctic/images/MODIS/Kane/20160506s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20160506s01a.ASAR.jpg) and tides are fairly extreme, http://www.tide-forecast.com/locations/Payer-Harbour-Cape-Sabine-Ellesmere-Island-Nunavut/tides/latest (http://www.tide-forecast.com/locations/Payer-Harbour-Cape-Sabine-Ellesmere-Island-Nunavut/tides/latest) http://www.tide-forecast.com/locations/Rensselaer-Bugt-Greenland-2/tides/latest (http://www.tide-forecast.com/locations/Rensselaer-Bugt-Greenland-2/tides/latest) so we may see some more break off, but imho nothing major.
Title: Re: The Nares Strait thread
Post by: bbr2314 on May 07, 2016, 08:54:35 PM
I am no expert on Nares but DMI still shows same outcome. I wonder if it is because the entire CAB is fracturing?

Not complete image, but today's satellite shows the cracks from the Beaufort catastrophe nearly reaching Nares vicinity...
Title: Re: The Nares Strait thread
Post by: johnm33 on May 13, 2016, 03:30:28 PM
Werther thinks we may see some action here soon, so heres a reference point
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKane%2F20160512s01a.ASAR.jpg&hash=5be2aa2a5733fee322d034ba289a29a7)
the currents are running south at -1.5C and up to .13mps [nullschool] and salinity has dropped according to hycom so bottom melt is underway. I think they're internal waves to the south which is why they're so big,[and they've shown up before in that spot] google internal waves images for comparison. for a bigger pic. http://ocean.dmi.dk/arctic/images/MODIS/Kane/20160512s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20160512s01a.ASAR.jpg)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 13, 2016, 03:57:34 PM
DMI's Terra images  (http://ocean.dmi.dk/arctic/kane.uk.php)of the north end of Kane Basin (and up Nares Strait) show how thin the snow cover is there.  Individual floes can be seen, now, as well as brown earth.  (The Sentinel images always show the floe outlines.) (Edit: you can compare this snapshot with the one I took 10 days ago of the same area.)
Title: Re: The Nares Strait thread
Post by: johnm33 on May 27, 2016, 12:34:29 AM
Check out that turbulence
 (https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FQaanaaq%2F20160526s01a.ASAR.jpg&hash=037b3963aefc8b481ad199f567b08759)
http://ocean.dmi.dk/arctic/images/MODIS/Qaanaaq/20160526s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Qaanaaq/20160526s01a.ASAR.jpg)
Title: Re: The Nares Strait thread
Post by: ghoti on May 27, 2016, 03:13:09 AM
Seeing little nibbles of ice have been coming off the arch in the last week or so via worldview. Seems early for the arch to fail but if bits keep falling it might lose stability.
Title: Re: The Nares Strait thread
Post by: oren on May 27, 2016, 06:16:34 AM
Seeing little nibbles of ice have been coming off the arch in the last week or so via worldview. Seems early for the arch to fail but if bits keep falling it might lose stability.

Indeed. Here's a big piece detached from the Ellesmere side. Little bits falling off is typical for the date but the action seems stronger this year.
Usually movement starts north of the arch and the ice becomes mobile in June, and then the arch collapses (last year it was early July). As the whole Arctic is on the loose this year, there is a chance of this process happening much earlier.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKane%2F20160526s01a.ASAR.jpg&hash=e8cee67ab634fa412ee7340303b61393)
Title: Re: The Nares Strait thread
Post by: Neven on May 27, 2016, 10:03:13 AM
There was a clear LANCE-MODIS image yesterday, and those beautiful wisps of cloud caught my eye. And how about that small polynya on the western (upper) side of the arch? Could that impact stability?
Title: Re: The Nares Strait thread
Post by: bbr2314 on May 27, 2016, 11:48:15 PM
There was a clear LANCE-MODIS image yesterday, and those beautiful wisps of cloud caught my eye. And how about that small polynya on the western (upper) side of the arch? Could that impact stability?
Believe it already has, note today's image, a huge chunk has broken off and drifted significantly.

Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 28, 2016, 01:13:15 AM
...
And how about that small polynya on the western (upper) side of the arch? Could that impact stability?
Believe it already has, note today's image, a huge chunk has broken off and drifted significantly.
A polynya forms there "early" every year (e.g., see this 2011 ASIB post (http://neven1.typepad.com/blog/2011/06/2011-nares-strait-animation.html)), so I doubt it has much affect on the Kane Basin arch, at least not differently from any other year.
Title: Re: The Nares Strait thread
Post by: Neven on May 28, 2016, 11:11:22 AM
Thanks, Tor, but I'm referring to the polynya near the arch, not the one above it.
Title: Re: The Nares Strait thread
Post by: Neven on May 28, 2016, 11:57:58 AM
Here's an animation showing the last 5 days on LANCE-MODIS. I think that arch looks stable enough, and the ice will have to turn blue before it breaks. There was a polynya in a similar position back in 2012 (http://neven1.typepad.com/blog/2012/06/nares-strait-2012-ice-arch-collapsing.html), and that's where the arch failed first, but this year's arch is a bit further back, so I'm not sure if the polynya will impact that corner. Either way, I think it's going to take a couple of weeks for the arch to break, probably before June is out.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 29, 2016, 01:36:20 PM
Woops  ::)
(- At the Florida Folk Festival all day yesterday and today - oldest continuously held annual folk music event in the US  :) )
Title: Re: The Nares Strait thread
Post by: Neven on May 31, 2016, 12:48:19 AM
Below is an animation showing changes in the past week (some ice broke off and that small polynya got bigger). And in the second image - regional ASAR from the DMI website (http://ocean.dmi.dk/arctic/kane.uk.php) - the white circle represents my curiosity at what will happen if that piece of ice between the small polynya and the open water in Kane Basin gives way. Will that compromise arch stability, or will the arch just retreat to a more stable position?
Title: Re: The Nares Strait thread
Post by: oren on May 31, 2016, 12:53:09 AM
The animation shows small differences that are hard to see when browsing each image separately. How very interesting - it really does look as if it might lose stability if that small remaining part breaks apart, even though the date is early and the ice is not slushy yet behind the arch.
Title: Re: The Nares Strait thread
Post by: johnm33 on June 02, 2016, 11:44:57 AM
I thought i'd take a look at last year, just a hint on this image
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150606TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150606TERR.jpg) not much more on the next
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150609TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150609TERR.jpg) some progress
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150613TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150613TERR.jpg) at last it's open but take a look to the north
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150616TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150616TERR.jpg) more action to the north[east] and some straight lines appearing along Ellesmere coast
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150617TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150617TERR.jpg) nothing to see here move along
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150619s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150619s01a.ASAR.jpg) it begins
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150620TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150620TERR.jpg) shame about the clouds
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150622AQUA.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150622AQUA.jpg) what?
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150626TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150626TERR.jpg) a little cloudy but the west side gives
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150703TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150703TERR.jpg) now the greenland side
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150704s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150704s01a.ASAR.jpg) clouds
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150706TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150706TERR.jpg) sentinel
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150706s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150706s01a.ASAR.jpg) here we go
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150709AQUA.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150709AQUA.jpg) ditto
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150710TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150710TERR.jpg) ditto
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150712TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150712TERR.jpg) boom
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150714TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150714TERR.jpg) boom
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150720TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150720TERR.jpg) boom boom
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150722TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150722TERR.jpg)
A more or less local tide timetable for last year http://www.dmi.dk/fileadmin/user_upload/vandstand_txt_pdf/2015/Pituffik2015.pdf (http://www.dmi.dk/fileadmin/user_upload/vandstand_txt_pdf/2015/Pituffik2015.pdf) and this years http://www.dmi.dk/fileadmin/user_upload/vandstand_txt_pdf/2016/Pituffik2016.pdf (http://www.dmi.dk/fileadmin/user_upload/vandstand_txt_pdf/2016/Pituffik2016.pdf) and the Ellesmere side http://www.tide-forecast.com/locations/Payer-Harbour-Cape-Sabine-Ellesmere-Island-Nunavut/tides/latest (http://www.tide-forecast.com/locations/Payer-Harbour-Cape-Sabine-Ellesmere-Island-Nunavut/tides/latest)
So it sort of kicks off when the tidal peak happens around the 17/6 but then eases, the next tidal peak is around the 5/7/15 [or07/05/2015 US style] which proves enough and it doesn't recover, and is smashed in the build up to the next peak tides. Will the high/low tides coming around the 5/6th be enough?
Title: Re: The Nares Strait thread
Post by: silkman on June 06, 2016, 09:24:39 AM
Big changes at the Western end of the Nares Strait this weekend. The polynya closest to the Strait is joining the main stream. Collapse of the current arch imminent?

https://lance.modaps.eosdis.nasa.gov/imagery/subsets/?subset=Arctic_r03c02.2016157.terra
Title: Re: The Nares Strait thread
Post by: A-Team on June 06, 2016, 03:56:13 PM
At the maximum resolution available, 250 m. Terra and Aqua aren't too far apart in image timing so the Nares Strait is changing rapidly (or we got lucky in capturing the event). Bands 367 processed out to the scan line limit show frozen-in floes and possibly future break lines.

Quote
Terra's orbit around the Earth is timed so that it passes from north to south across the equator in the morning, while Aqua passes south to north over the equator in the afternoon [in the A-train].

It's not clear from the metadata how much time elapsed between the two swaths relevant to the Nares arch (which is on the extreme right of the image), so possibly 10:50 for Aqua and 13:40 for the Terra for 2 hours and 50 minutes. The orbit map is unreadable: https://lance.modaps.eosdis.nasa.gov/imagery/realtime/orbitmaps/2016157/orbitmap1.global.2016157.gif

5 minute swath data used for Terra image:
13:40 UTC
13:45 UTC
15:20 UTC
15:25 UTC
17:00 UTC
18:35 UTC
18:40 UTC
20:15 UTC
21:55 UTC

5 minute swath data used for Aqua image:
10:50 UTC
12:25 UTC
14:05 UTC
15:40 UTC
15:45 UTC
17:20 UTC
18:55 UTC
19:00 UTC
Title: Re: The Nares Strait thread
Post by: oren on June 06, 2016, 05:15:59 PM
Amazing. The whole Ellesmere side of the lower arch is gone in one big poof. I looked yesterday for changes and there was no hint of this coming.
Is the ice mobile enough above the arch to follow on this structural loss of support? We shall soon see.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 06, 2016, 07:56:56 PM
A close comparison between the latest (2016-06-06) and an earlier (2016-06-03) DMI Sentinel image suggests to me that there has been a small movement of the ice away from the rocky (southern) Greenland side of Kane Basin.  If this is real, most of the ice in at least Kane Basin will break up soon.
Title: Re: The Nares Strait thread
Post by: Shared Humanity on June 07, 2016, 03:39:02 PM
If you look at the animated image just above (orange) you will see a feature in the arch that is absolutely critical to stability of the arch. From an architectural point of view, the most important stone is the keystone, the stone that sits at the very top of the arch in the center. This stone carries the highest stress load and when this stone is compromised or removed, the arch will collapse quickly. Often, you will find the keystone is larger than the other stones that form the arch. On this animation, the keystone, a large ice flow of multi-year ice is clearly visible. If we see this floe fracture or if we see the ice around it which is mainly small bits of MYI and FYI which has frozen them in place begin to disintegrate, it is a suggestion of imminent collapse. I would pay particularly close attention to the prominent bulge of ice that protrudes into the open water at the top of the arch on the west side of the keystone. If this gives way, the keystone will lose its support and the arch will collapse IMHO. In that most recent calving, it appears as if this bulge was compromised or chipped away at.

By the way, having ice peel away from the sides, near the base of the arch, increases the load and stress on the keystone.
Title: Re: The Nares Strait thread
Post by: Neven on June 07, 2016, 04:14:22 PM
what will happen if that piece of ice between the small polynya and the open water in Kane Basin gives way. Will that compromise arch stability, or will the arch just retreat to a more stable position?

It looks like it's going to be the latter. I still think this is going to take a while longer, until the ice gets blue.
Title: Re: The Nares Strait thread
Post by: johnm33 on June 07, 2016, 04:26:23 PM
An alternative veiw could be that the thrust from Humbolt is what forces the collapse, so as more warm water passes through and thins out the 'structural' ice eventually the build up of pressure in Humbolt proves too much.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKane%2F20140607rs02.ASAR.jpg&hash=8db2f833c3d1c50f14ed5f45f2255a11)
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20140607rs02.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20140607rs02.ASAR.jpg)
Title: Re: The Nares Strait thread
Post by: Sonia on June 09, 2016, 01:31:51 PM
I thought i'd take a look at last year, just a hint on this image
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150606TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20150606TERR.jpg) not much more on the next
...
Will the high/low tides coming around the 5/6th be enough?
I like this summary a lot because it shows how the breakup was spread out over a month.  Tides in early June last year anyway might have helped start things but weren't enough for a complete breakup.  This year is looking similar.

Neven is watching for blue ice; he may not have long to wait.  Wipneus observes some melting starting from the AMSR2 data.  http://forum.arctic-sea-ice.net/index.php/topic,382.msg79648.html#msg79648 (http://forum.arctic-sea-ice.net/index.php/topic,382.msg79648.html#msg79648)  That's consistent with the recent temperatures at Hans Island.
Title: Re: The Nares Strait thread
Post by: Neven on June 10, 2016, 08:11:05 PM
I didn't expect this, looks weird. What happened here (day before yesterday, day 160)?

(https://lh3.googleusercontent.com/-D5isy6JIL2A/V1sCa1_QdiI/AAAAAAAAC9g/cPyEPF4bp18hWDLRX2drlpB4p08WJ4Y0ACCo/s482/Arctic_r03c02.2016161.terra.500m.jpg)

Ice broke off, and then got pushed back against the arch? Animation shows days 151, 157, 158, 160 and 162 (today).

(https://lh3.googleusercontent.com/-fGHE4-52670/V1sCcyJCoWI/AAAAAAAAC9o/WqyVsthsjx0zkFxW01mFso7v421lqswyQCCo/s482/NARES%2B151-157-158-161-162.gif)
Title: Re: The Nares Strait thread
Post by: johnm33 on June 10, 2016, 08:20:52 PM
Very odd maybe the wind?  https://earth.nullschool.net/#2016/06/08/1800Z/wind/surface/level/orthographic=-74.44,76.18,3000/loc=-72.967,78.818 (https://earth.nullschool.net/#2016/06/08/1800Z/wind/surface/level/orthographic=-74.44,76.18,3000/loc=-72.967,78.818)
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2FpnXLc%2F85885173c1.jpg&hash=7f9808ad5708e102b1bf0554f60d7fa5)
Sonia"I like this summary a lot" thanks. It's worth looking at 2014 too, best on worldveiw http://go.nasa.gov/1UqX6xh (http://go.nasa.gov/1UqX6xh) this is the 20th apart from Humbolt ice getting bluer nothing much has changed since the 10th but it breaks on the 23rd and just slowly continues to break from then on. The full moon was on 13:06 and new moon 27:06
 The next big tides are on the 20/21 but will everything be in place for the break?
Title: Re: The Nares Strait thread
Post by: magnamentis on June 10, 2016, 09:35:12 PM
I didn't expect this, looks weird. What happened here (day before yesterday, day 160)?

winds ?
Title: Re: The Nares Strait thread
Post by: oren on June 11, 2016, 11:11:54 AM
Now the flow has been reversed again, and there's been another big breakup on the northwest ( Ellesmere) side. Seems the weak ice of this season due to poor winter came here too. Usually the ice becomes mobile behind the arch, and finally the arch gives way. This year it's the opposite.
Title: Re: The Nares Strait thread
Post by: johnm33 on June 14, 2016, 10:31:44 AM
There are weaknesses appearing on the Ellesmere shore
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKane%2F20160613TERR.jpg&hash=c8586d323e33d0ac85cd7e67c86ed5e5)
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20160613TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20160613TERR.jpg)
they extend up into Kennedy too with some on the Greenland side, I see this as indicating thinning, which as yet is not visible, taking place. The tides are increasing so this will only accelerate, will it hold till the tides turn on 21st I'm inclined to think not, but it depends on how much pent up energy is restrained in Humbolt.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKennedy%2F20160613TERR.jpg&hash=7f0d5f0f3c83a4809c91214908e24e3f)
http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20160613TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20160613TERR.jpg)
Title: Re: The Nares Strait thread
Post by: johnm33 on June 15, 2016, 10:18:32 AM
Looking at these two images 2 days apart the ice looks a little bluer Ellesmere side, by the entrance to Kane it's fairly subtle so better seen in the links.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKane%2F20160612TERR.jpg&hash=cb05ec7e5b92a50d629cb07f45933c26)
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20160612TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20160612TERR.jpg)
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKane%2F20160614TERR.jpg&hash=6f5b45b90d174814f954e4f30b60d136)
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20160614TERR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20160614TERR.jpg)
Title: Re: The Nares Strait thread
Post by: Tealight on June 15, 2016, 10:10:09 PM
S2A shows a new crack developing from a polyna on the canadian side.
Title: Re: The Nares Strait thread
Post by: johnm33 on June 17, 2016, 01:06:32 PM
It could be nothing but open the link and switch between 15/16 from roughly bottom center there's a broad swathe at about 600 getting bluer faster than it's surroundings.
http://go.nasa.gov/1UcY3tA (http://go.nasa.gov/1UcY3tA)
Title: Re: The Nares Strait thread
Post by: oren on June 17, 2016, 01:15:45 PM
It could be nothing but open the link and switch between 15/16 from roughly bottom center there's a broad swathe at about 600 getting bluer faster than it's surroundings.
http://go.nasa.gov/1UcY3tA (http://go.nasa.gov/1UcY3tA)

Yes there is. And this whole blue area did not exist a few days ago.
While scrolling I noticed that the bottom-most (Greenland) corner of the arch crumbled and cleared in the past few days, starting from around June 11th.
Title: Re: The Nares Strait thread
Post by: Neven on June 17, 2016, 01:55:22 PM
Yup, things are turning blue. Let's see if the arch makes it to the end of the month (probably not).
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 17, 2016, 07:48:51 PM
Oren wrote: "While scrolling I noticed that the bottom-most (Greenland) corner of the arch crumbled and cleared in the past few days, starting from around June 11th." 
About 10 days ago I reported what I believed to be a 'change' in the ice along Greenland's rocky shore in Kane Basin.  The ice-free end of the arch may be a manifestation of what I'd seen.

Neven wrote: "Let's see if the arch makes it to the end of the month (probably not)."  I also expect the Kane Basin ice to break in June.  I have no opinion about the ice in rest of Nares Strait, though.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 20, 2016, 04:18:13 PM
cross post - Thanks philiponfire - post #694 in Arctic Image of the Day (http://forum.arctic-sea-ice.net/index.php/topic,416.650/topicseen.html):
Floes have been breaking off regularly in Kane basin for the last month and now we can see the beginning of the break up of Nares strait from the north end.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 20, 2016, 04:25:54 PM
Cracks also appear within Nares Strait just 'south' of the Lincoln Sea. (North is, more-or-less, to the right.)

(The unsupported Greenland corner of the ice bridge in Kane Basin broke off.)
Title: Re: The Nares Strait thread
Post by: johnm33 on June 20, 2016, 08:12:47 PM
Big tides, ice thinning [turning blue] and cracks up in Kennedy, I don't think it'll hold till the weekend.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2FpzEVr%2F79449d1e5b.png&hash=0325b224b47d698bab8dd709a00e961b)
Title: Re: The Nares Strait thread
Post by: oren on June 20, 2016, 10:49:41 PM
Cross-posting for future reference.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 22, 2016, 03:37:22 PM
As best I could, these two images cover the same area (June 19 (https://lance.modaps.eosdis.nasa.gov/imagery/subsets/?subset=Arctic_r03c02.2016171.terra) and June 21 (https://lance.modaps.eosdis.nasa.gov/imagery/subsets/?subset=Arctic_r03c02.2016173.terra)).  Note the continuing loss of fast ice along the Greenland (lower left) shore, apparently beyond the new leading edge of the ice bridge (aka ice arch) as it had done last week.  Although the bridge end got trimmed (between the two dates), most of the bulge on the Greenland side of the bridge appears to be in exactly the same place in both images.  Other areas along the bridge, however, notably the furthest-to-the-right arch apex and the arch edge next to the largest broken-off floe in the June 19 image, appear to show the bridge slowly collapsing (that is, moving 'left').

[I wish I could do an animation! With two browser tabs, one open to each date on the Rapid Response - LANCE images (links to source images on dates above), I positioned the images so Greenland shores exactly matched when I clicked back and forth.  I captured the posted images that matched areas, as best I could (for left, right and top edges by using browser window references that didn't change between images).]
Title: Re: The Nares Strait thread
Post by: johnm33 on June 22, 2016, 09:37:26 PM
Tor "I wish i could do an animation" me too, but with Worldview you just click and hold, all the 'chunks' in the pack are stationary, but it keeps getting bluer. http://go.nasa.gov/28Oc6qE (http://go.nasa.gov/28Oc6qE)
Title: Re: The Nares Strait thread
Post by: Laurent on June 22, 2016, 11:05:15 PM
If I can do it, you can do it !
Open Worldview, choose the place you want to record then press print screen button on your keyboard.
Do that for each frame.
Go to your directory, right click on the first file, choose open with Gimp (http://www.gimp.org/downloads/ (http://www.gimp.org/downloads/))
Be sure you have the "tracing paper" window open (ctrl + L) !
Go to file>open as a calc choose the second, then repeat until you have all the frames.
Crop the part that you want. (use the tool cutter for that)
Go to Image>scale image rescale to 650 pixel in length
Go to File>Export as> choose Gif and rename the file extension as gif.
Ask to use  a time between frames that does suit you (1000 ms).
That's it.
By the way, I don't find the animation particularly interesting.
Title: Re: The Nares Strait thread
Post by: oren on June 23, 2016, 07:10:05 AM
If I can do it, you can do it !
...
By the way, I don't find the animation particularly interesting.

Thanks for the detailed reminder. Did it a few times in the past with Gimp, but it's still mentally complicated.

As to the animation, careful eyeballing shows not just the Greenland corner peeling away, and then the whole section after it slowly disappearing, but also the whole left half of the arch moving slightly but definitely forward in the last couple of frames - which might mean total loss of structural support and the ice becoming mobile at last.
This is what Tor reported, but watching it live made it much easier to see.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 23, 2016, 07:07:06 PM
Thanks, oren, for seeing what I saw and what shows it the Worldview animation.  (For others, carefully place your mouse's pointer exactly on the arch's edge near where the largest ice floe separates (near the apex of the arch), and see that the ice edge moves southward (left) in the last few frames.)

Yes, the animation is 'required' to see the movement.

And thanks, Laurent, for the tutorial.  This old dog might be able to learn this new trick!
Title: Re: The Nares Strait thread
Post by: johnm33 on June 23, 2016, 10:43:17 PM
Here we go, maybe
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2FpDuSm%2F45c6aa0e7c.jpg&hash=8a7c9d8826c0cfe54e49aa45002687d1)
http://go.nasa.gov/290kYdn (http://go.nasa.gov/290kYdn)
Thanks Laurent if the fog ever clears [in my head] I'll learn that.
Title: Re: The Nares Strait thread
Post by: oren on June 23, 2016, 11:15:05 PM
A big one! It seems collapse is underway.
I also notice that suddenly all the ice in Kennedy Channel is fractured into floes.
Title: Re: The Nares Strait thread
Post by: Adam Ash on June 24, 2016, 01:07:15 PM
While the ice bridge has been holding, there has been continual small scale ice movement in action along the coast of Ellesmere Island just north of the bridge...
Title: Re: The Nares Strait thread
Post by: Buddy on June 24, 2016, 06:06:12 PM
Quote
A big one! It seems collapse is underway.

Oren....when is the "usual time" for the collapse over the last 5 years or so?  Is it June...July...other?  Thanks....  Buddy
Title: Re: The Nares Strait thread
Post by: oren on June 24, 2016, 07:50:02 PM
Quote
A big one! It seems collapse is underway.

Oren....when is the "usual time" for the collapse over the last 5 years or so?  Is it June...July...other?  Thanks....  Buddy

I am hardly the expert on the subject (or any subject on this great forum) but browsing this thread's back pages will give you the answer you seek.
Looking back to 2015 it happened at around July 10th, but the order of things was somewhat reversed - first the ice started breaking up all along the Strait, later the arch started losing bits and pieces, and finally the ice from the north gave it one big push and it started moving and was gone. This year the bits and pieces part came much earlier, the ice breaking up at around the same time. I highly doubt the final part will wait til July 10th, it may have started already (the movement that Tor spotted).

Here's an animation of last year's process.

http://forum.arctic-sea-ice.net/index.php/topic,176.msg56610.html#msg56610 (http://forum.arctic-sea-ice.net/index.php/topic,176.msg56610.html#msg56610)

When I have time later I'll browse other years, but feel free to do it yourself  ;) - it's an interesting exercise.
Title: Re: The Nares Strait thread
Post by: Jim Hunt on June 24, 2016, 10:49:45 PM
There's significant movement further north (http://go.nasa.gov/28VizSL) now also:
Title: Re: The Nares Strait thread
Post by: Laurent on June 25, 2016, 11:03:10 PM
.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 26, 2016, 04:35:39 AM
As the last frame of Laurent's gif shows, fissures near the 'north' end of Kane Basin are opening.  (I didn't notice them until I looked at a DMI Satellite Image (http://ocean.dmi.dk/arctic/kane.uk.php)).
Title: Re: The Nares Strait thread
Post by: be cause on June 26, 2016, 06:04:39 AM
Yes .. it looks like a door is opening for yet more of the multi-year ice to exit the Arctic .
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 26, 2016, 08:25:49 PM
Today's Lance MODIS shows new fissures in the northern (Greenland side) of Kane Basin, next to (edit: near) the Humboldt Glacier (attached).  Yesterday's DMI image of the Kane Basin ice bridge suggests to me that 'something' might be missing (that is, a chunk of ice) through the clouds near the Greenland side, but time (a few hours?) will tell.  (Edit after the full-Kane-Basin image below:  no missing ice, just melt ponding.)
Title: Re: The Nares Strait thread
Post by: johnm33 on June 26, 2016, 10:43:39 PM
High tide passed at about 20:00utc so maybe the next image will be of collapse, it sure looks primed.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2FpGZI1%2F9107adf41a.jpg&hash=21a8a4719f1da33ceb538a9cd9c98ced)
http://go.nasa.gov/28ZdFEy (http://go.nasa.gov/28ZdFEy)
Title: Re: The Nares Strait thread
Post by: Adam Ash on June 27, 2016, 02:33:53 AM
Love the movement, south, south NORTH!  Not much integrity there..
Title: Re: The Nares Strait thread
Post by: johnm33 on June 28, 2016, 10:45:01 AM
Slow collapse continues beneath the clouds
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2FpIO4N%2F6f46ecfde2.jpg&hash=1e5ced91140213df142d6aa81f60655f)
from http://www.polarview.aq/images/106_S1jpgsmall/201606/S1A_EW_GRDM_1SDH_20160627T213037_BF6B_N_1.jpg (http://www.polarview.aq/images/106_S1jpgsmall/201606/S1A_EW_GRDM_1SDH_20160627T213037_BF6B_N_1.jpg)
Title: Re: The Nares Strait thread
Post by: Adam Ash on June 28, 2016, 12:13:35 PM
There does not seem to be any 'integrity' / glue holding anything in the Straight together does there.  Is if a combination of wind opposed to current that is keeping it in position?  Its going to go like slush down a drain once it gets a sense of direction!
Title: Re: The Nares Strait thread
Post by: johnm33 on June 29, 2016, 12:17:04 AM
"does not seem to be any 'integrity'" It looks broken , but if it was it'd be ripping out of there fast. At the moment there are @8ft. tides[2.4m] which usually means enhanced flows from the north, you can just see the internal waves generated by the flow on my last post, that image is about 1/2 hr. after high tide, the tides are at least as important for the amount of melt they generate as they are for movement, the melt, whilst it thins also glues the ice back together. So you get a lot of melt [and compression] further north, but if it's cold enough in the south it refreezes sometimes extending the arch sometimes just binding it. It's a fools errand trying to predict it, I'm looking for a cure.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2FpJtc1%2F0f5e5079cf.jpg&hash=16f8e4e0c1a24f64cb641c2446baea15)
from http://go.nasa.gov/29ddfsv (http://go.nasa.gov/29ddfsv)
Title: Re: The Nares Strait thread
Post by: Adam Ash on June 29, 2016, 01:21:21 AM
Hi John!  I suspect that our 'cure' is a good old dose of 'patients'!  Its all very interesting, in a remote sort of way - a bit like watching gangrene moving up your leg - eventually it will take us out.
Title: Re: The Nares Strait thread
Post by: oren on June 29, 2016, 07:26:40 AM
It's a fools errand trying to predict it, I'm looking for a cure.

You are so right... Still my gut feeling is a few days will see this mess moving.  ???
Title: Re: The Nares Strait thread
Post by: Neven on June 29, 2016, 09:36:24 AM
I agree, this can't take long. I think it'll break up within days now.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 03, 2016, 05:00:31 AM
It's gotta break soon!  (But I had predicted 'during June', so I lost that bet!)
From: https://lance.modaps.eosdis.nasa.gov/imagery/subsets/?subset=Arctic_r03c02.2016184.terra.250m
Title: Re: The Nares Strait thread
Post by: Laurent on July 03, 2016, 09:57:47 AM
An other view :
Title: Re: The Nares Strait thread
Post by: johnm33 on July 03, 2016, 01:47:49 PM
It's breaking apart, big tides, 4m greenland side 2.8m Ellesmere, winds blowing north [nullschool] pushing the ice away in Lincoln, that'll mean warmer water coming from the north. My guess is it'll all be running through by the 6th.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 03, 2016, 08:50:31 PM
From http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SSH_20160703T123301_7B7C_N_1.final.jpg (http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SSH_20160703T123301_7B7C_N_1.final.jpg)
Cracking along the Greenland shore.  No image I have access to shows the crack going to the arch's underside, though.

Title: Re: The Nares Strait thread
Post by: JayW on July 04, 2016, 12:49:30 PM
Edit: I totally jumped the gun, just clouds.  :-\

Sorry for the terrible resolution, but looking at AVHRR images from the Canadians, it appears the Nares may have blown out in the last couple hours.  Edit: it was somewhere between 0743z and 0924z.

http://weather.gc.ca/satellite/satellite_anim_e.html?sat=hrpt&area=dfo&type=nir (http://weather.gc.ca/satellite/satellite_anim_e.html?sat=hrpt&area=dfo&type=nir)
Title: Re: The Nares Strait thread
Post by: Shared Humanity on July 04, 2016, 04:07:27 PM
Low resolution or not, thanks for the animation. It is obvious that Kane Basin has collapsed. Not as clear what is going on north of the basin.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 04, 2016, 09:43:18 PM
I presume these cracks go to the bridge's leading ice edge.
image from https://lance.modaps.eosdis.nasa.gov/imagery/subsets/?subset=Arctic_r03c02.2016186.terra.250m
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 05, 2016, 04:04:06 AM
The Kane Basin ice bridge is (confirmed) broken.
From http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SDH_20160704T212223_46AE_N_1.final.jpg, (http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SDH_20160704T212223_46AE_N_1.final.jpg,) the Greenland shore is at the bottom of the image and open water is on the left.  70 and 72W lines of longitude show, as does the 79N parallel.

The Canadian side has also broken (2nd image - 72 and 74W lines of longitude show).

The next question I have is:  When will the first piece of (current) Lincoln sea ice flow through the entire strait?
Title: Re: The Nares Strait thread
Post by: Adam Ash on July 05, 2016, 04:41:36 AM
Nares is ready to rumble!
Title: Re: The Nares Strait thread
Post by: crandles on July 07, 2016, 01:16:20 PM
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKane%2F20160706TERR.jpg&hash=314fe4ee41257a4a54d0a161267c33d7)

going ..... going .....

Could that big block in the middle stay whole and block the narrow entrance? I would expect that much movement would cause further break ups but it would be an unusual date for an arch formation.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 07, 2016, 02:37:26 PM
...
going ..... going .....
...
I'm not gonna to hold my breath about the ice "going" anywhere!  :D
It 'wanted' to break up, but it appears it likes where it is.
Title: Re: The Nares Strait thread
Post by: johnm33 on July 07, 2016, 04:27:59 PM
"going  going"
That shot was about 17:00 utc not long after a 'low' high tide there was a big tide just before midnight and with winds blowing south odds are it's moving as we wait for updates.
Title: Re: The Nares Strait thread
Post by: crandles on July 07, 2016, 07:30:12 PM
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKane%2F20160707s01a.ASAR.jpg&hash=3513f81d7acb6d744f256a531a4ffb96)

who gets to say "gone"?
Title: Re: The Nares Strait thread
Post by: johnm33 on July 08, 2016, 12:16:50 AM
I can't see this stopping now http://go.nasa.gov/29s9xgA (http://go.nasa.gov/29s9xgA)
Title: Re: The Nares Strait thread
Post by: oren on July 08, 2016, 12:30:52 AM
IMHO Big plug is a goner and a good part of the Basin (where the crushed ice is) should be flushed in a few days.
Title: Re: The Nares Strait thread
Post by: johnm33 on July 08, 2016, 09:23:15 PM
Going
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2FpUU1I%2F4cf317bed6.jpg&hash=b111e9d8c6c10bde4bb72cb04aa0ac57)
from http://go.nasa.gov/29Eh8ai (http://go.nasa.gov/29Eh8ai)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 08, 2016, 10:15:31 PM
or not hardly going yet  :D
(Attached image from LANCE MODIS (https://lance.modaps.eosdis.nasa.gov/imagery/subsets/?subset=Arctic_r03c03.2016190.terra.500m)) 
We have something for everyone!  ::)
Title: Re: The Nares Strait thread
Post by: oren on July 09, 2016, 12:43:22 AM
Interesting that as soon as Big Plug started to move, most of Kane Basin and the whole Kennedy Channel started to move with it. What seemed like good ice a few days ago was just waiting for the call.
Title: Re: The Nares Strait thread
Post by: johnm33 on July 09, 2016, 01:11:25 AM
I wonder if the hold-up is the pressure from Petermann, if that's the case, should be interesting when it breaks.
Title: Re: The Nares Strait thread
Post by: A-Team on July 10, 2016, 09:16:40 PM
Quote
effect on Petermann?
Back pressure might facilitate FYI/melange breakup. However the floating ice shelf will not be affected, nor will the glacier speed up measurably as a consequence (even using fixed differential GPS or the new S1AB interferometry capacity).

Indeed, loss of the entire ice shelf will have minimal effect on glacial discharge as it has been calculated to provide little buttressing -- which could have been anticipated from the lack of firm engagement with the rock walls.

It would be timely though to check if shelf crevasses have extended in recent months, best done with a Sentinel 2A matched pair. Enormous tabular bergs are newsworthy though in this instance they don't have the significance of those in Antarctica as Petermann is only a partial proxy for the floating ice shelves there.

Just a cross-posted animation of the last 4 days from the Nares poll forum:
Title: Re: The Nares Strait thread
Post by: oren on July 10, 2016, 10:53:55 PM
Quote
effect on Petermann?

I believe John's meaning was the possible effect of Petermann on the sea ice, not vice versa. More specifically on the side pressure from Petermann causing a block or slowdown in the middle of Nares.

The animation kind of answers that, that area is not blocked, though perhaps slowed down.

Edit: never mind, read your reply in the flushing poll thread.
Title: Re: The Nares Strait thread
Post by: johnm33 on July 11, 2016, 12:39:30 AM
"The animation kind of answers that" absolutely. Not that it couldn't all seize up for a few days either by Petermann or at the exit to Kane basin, I doubt it but we'll see.
Title: Re: The Nares Strait thread
Post by: oren on July 17, 2016, 10:01:04 AM
The whole Kane Basin is rushing to the exit to bathe in some hot water, except for some static ice on the Greenland side. The Kennedy Channel is already cleared.
Title: Re: The Nares Strait thread
Post by: johnm33 on July 18, 2016, 10:14:11 AM
Curious wave like feature on this image
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fimages%2FMODIS%2FKane%2F20160717s01a.ASAR.jpg&hash=e495758c0e5fd26f0d8705a891fff349)
polar view has it on this http://www.polarview.aq/images/106_S1jpgsmall/201607/S1A_EW_GRDM_1SSH_20160717T202512_C28B_N_1.jpg (http://www.polarview.aq/images/106_S1jpgsmall/201607/S1A_EW_GRDM_1SSH_20160717T202512_C28B_N_1.jpg) which gives the time so close to high tide, is it possible thats some type of tidal bore? get a better look http://ocean.dmi.dk/arctic/images/MODIS/Kane/20160717s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20160717s01a.ASAR.jpg)
Title: Re: The Nares Strait thread
Post by: solartim27 on July 18, 2016, 05:52:52 PM
It's the result of stitching together different images.
Curious wave like feature on this image
Title: Re: The Nares Strait thread
Post by: Cate on July 19, 2016, 12:08:53 AM
MAP REFERENCE
JOHN RICHARDSON  BAY on Ellesmere, just SW of Petermann
http://www.arctic.io/explorer/4Xa5A//4-N90-E0 (http://www.arctic.io/explorer/4Xa5A//4-N90-E0)

EDIT: Thanks to Tor Bejnar for help in pointing me to Espen's map of Ellesmere place names.

The area I'm looking at is John Richardson Bay on the Ellesmere side of Nares, between Cape Collinson to the south and Cape Wilkes to the north. If you toggle 17-18 July, it looks like a big chunk of ice breaks off the northern corner of the tongue of ice in the bay.

Can someone please confirm if that is what I am looking at there?

As for what the chunk is----the same area in September 2015 was dark blue water, so I would conclude that this chunk is shore-fast new or first year ice  in the bay. I wonder how thick it might be.

EDIT: Here is the permalink. John Richardson Bay is the middle fjord of the three on the Ellesmere side of the strait.

http://www.arctic.io/explorer/4Xa5A/2016-07-18/9-N80.30822-W67.93778 (http://www.arctic.io/explorer/4Xa5A/2016-07-18/9-N80.30822-W67.93778)
Title: Re: The Nares Strait thread
Post by: Iceismylife on July 19, 2016, 03:45:12 AM
Good spotting.  Nice link too.
Title: Re: The Nares Strait thread
Post by: Cate on July 19, 2016, 03:51:20 AM
Good spotting.  Nice link too.

Thanks. :)  Just added the permalink, which was what I meant to post. I also need to learn how to post the image with a circle drawn around the area of interest.
Title: Re: The Nares Strait thread
Post by: Alistair on July 19, 2016, 05:46:34 AM
What this also nicely shows up is the breaking up of the ice in front of Petermann between 17th and 18th (Was whole yesterday!)
Title: Re: The Nares Strait thread
Post by: Cate on July 19, 2016, 11:14:46 AM
What this also nicely shows up is the breaking up of the ice in front of Petermann between 17th and 18th (Was whole yesterday!)

Yes, big crack right across the fjord in a day. Pretty amazing, how fast it opens up.
Title: Re: The Nares Strait thread
Post by: johnm33 on July 19, 2016, 04:24:16 PM
Solartim27"it's the result of stitching"
No, the feature is not aligned with the obvious frames
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2Fq6Y4L%2Fb86fb4bade.jpg&hash=8952ed4979aff82584bb725fffbf1094)
also in close up it clearly curves
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2Fq6QEr%2Fac001d4de4.jpg&hash=e8caccbfd56e77eaf857c20d6577e126)
my guess is that there's a subsurface wave of warmer southern water being forced north, and the whitening is the spume generated by turbulence, making the surface far more reflective to radar. I can't find any trace of it on daylight images. If there was enough water driven north it should show up as warmer on nullschool when their sst's are updated.
Title: Re: The Nares Strait thread
Post by: solartim27 on July 19, 2016, 05:42:48 PM
my guess is that there's a subsurface wave of warmer southern water being forced north, and the whitening is the spume generated by turbulence, making the surface far more reflective to radar. I can't find any trace of it on daylight images. If there was enough water driven north it should show up as warmer on nullschool when their sst's are updated.
And the explanation for this is?
http://www.polarview.aq/images/106_S1jpgsmall/201607/S1A_EW_GRDM_1SDH_20160717T121804_BF09_N_1.jpg (http://www.polarview.aq/images/106_S1jpgsmall/201607/S1A_EW_GRDM_1SDH_20160717T121804_BF09_N_1.jpg)
Title: Re: The Nares Strait thread
Post by: Iceismylife on July 19, 2016, 06:18:20 PM
...
As for what the chunk is----the same area in September 2015 was dark blue water, so I would conclude that this chunk is shore-fast new or first year ice  in the bay. I wonder how thick it might be.

...
I looked through the freeze up and it looks to have been new ice not incorporating ice drifting in from somewhere else.  I don't know how thick it is.
Title: Re: The Nares Strait thread
Post by: Cate on July 20, 2016, 12:48:28 AM
...
As for what the chunk is----the same area in September 2015 was dark blue water, so I would conclude that this chunk is shore-fast new or first year ice  in the bay. I wonder how thick it might be.

...
I looked through the freeze up and it looks to have been new ice not incorporating ice drifting in from somewhere else.  I don't know how thick it is.

Just looking at today---there are clouds, but it looks like another big chunk of shore-fast has gone out of John Richardson Bay into the strait. And Petermann fjord is really clearing out now too.

http://www.arctic.io/explorer/4Xa5A/2016-07-19/9-N80.56333-W67.60169 (http://www.arctic.io/explorer/4Xa5A/2016-07-19/9-N80.56333-W67.60169)
Title: Re: The Nares Strait thread
Post by: plinius on July 27, 2016, 01:12:58 AM
Am I correct that the Nares is flushing, but no ice reaches Baffin Bay due to the high water temperatures (depending on how one defines Smith sound and Baffin)?
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on August 27, 2016, 03:41:18 PM
I believe you are correct, but strong winds may move some ice that overwintered in Lincoln Sea into Baffin Bay soon.  I've been watching this on the Nares Strait Flushing Poll (http://forum.arctic-sea-ice.net/index.php/topic,1599.msg82643.html#msg82643) thread.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on August 27, 2016, 03:57:02 PM
According to the HYCOM model (https://www7320.nrlssc.navy.mil/hycomARC/arctic.html), some really thick sea ice will move into the Lincoln Sea over the next several days (September 3 forecast copied below).  The Lincoln Sea does occasionally get filled with 5m ice (April 2014, for example).

I'm guessing the actual floes are small enough so that they will flush all the way through Nares Strait.  Who knows: this may be the first Arctic ice to make it!

(https://www7320.nrlssc.navy.mil/hycomARC/navo/arcticictn/nowcast/ictn2016082618_2016090300_046_arcticictn.001.gif)
Title: Re: The Nares Strait thread
Post by: johnm33 on September 18, 2016, 11:37:10 PM
This just has to be here too, from A-Team 4839 on melt season.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fforum.arctic-sea-ice.net%2Findex.php%3Faction%3Ddlattach%3Btopic%3D1493.0%3Battach%3D36393&hash=39674a165d62e417a2024e8fd0b9de66)
In Nares when the southern waters are forced north by the tides, they 'turn right' and hug the Greenland coast accelerating melt at Humbolt and Peterman, sometimes forcing through to Lincoln. Conversely when the tidal flow is south the arctic waters flow down Ellesmeres coast as illustrated by A-Teams excellent animation. To get a fuller picture, given that these animations are based on one shot per day and can barely hint at the tides, it's worth spending a little time looking through the various products here http://marine.copernicus.eu/services-portfolio/access-to-products/ (http://marine.copernicus.eu/services-portfolio/access-to-products/)
Compare this to A-Teams animation, this just shows the settings the permalink doesn't animate, it's from the first product in the catalogue. Animation wizard bottom left.
http://cmems-view.cls.fr/ViewService/?permalinking=true&bgmap=Blue%20Marble%20North%20Polar&dataset=http://nrtcmems.mercator-ocean.fr/thredds/wms/global-analysis-forecast-phys-001-002&numColorBands=20&logScale=false&bbox=226464.84375,1169042.96875,3637109.375,3649511.71875&abovemaxcolor=0x000000&belowmincolor=0x000000&nodatacolor=null&layer=v&time=2016-09-19T12%253A00%253A00.000Z&palette=rainbow&style=boxfill&scaleRange=-0.98330635,0.4992828&displayScaleRange=-0.98330635,0.4992828&opacity=1&record_id=ceec7b06-49e3-4c13-bfdb-1cc8d4dc423d&dataset_id=daily%20mean%20fields%20from%20Global%20Ocean%20Physics%20Analysis%20and%20Forecast%20updated%20Daily (http://cmems-view.cls.fr/ViewService/?permalinking=true&bgmap=Blue%20Marble%20North%20Polar&dataset=http://nrtcmems.mercator-ocean.fr/thredds/wms/global-analysis-forecast-phys-001-002&numColorBands=20&logScale=false&bbox=226464.84375,1169042.96875,3637109.375,3649511.71875&abovemaxcolor=0x000000&belowmincolor=0x000000&nodatacolor=null&layer=v&time=2016-09-19T12%253A00%253A00.000Z&palette=rainbow&style=boxfill&scaleRange=-0.98330635,0.4992828&displayScaleRange=-0.98330635,0.4992828&opacity=1&record_id=ceec7b06-49e3-4c13-bfdb-1cc8d4dc423d&dataset_id=daily%20mean%20fields%20from%20Global%20Ocean%20Physics%20Analysis%20and%20Forecast%20updated%20Daily)
and something completely different https://www.the-saleroom.com/en-gb/auction-catalogues/david-lay-f-r-i-c-s/catalogue-id-srdavid10044/lot-de682db3-1a16-43dd-b81e-a6750124ba2d (https://www.the-saleroom.com/en-gb/auction-catalogues/david-lay-f-r-i-c-s/catalogue-id-srdavid10044/lot-de682db3-1a16-43dd-b81e-a6750124ba2d)
Title: Re: The Nares Strait thread
Post by: johnm33 on September 23, 2016, 10:41:52 AM
Last chance folks these are under the hammer.
"A set of 42 magic lantern slides of photographs taken by Thomas Mitchell & George White during the British Arctic Expedition 1875-1876. Produced by The London Stereoscopic Company (Optical Department) 110 & 108 Regent St. and 54 & 53 Cheapside, London. Each slide: 8.7cm x 8.7cm. Each image: 6cm x 6.7cm. Each slide hand numbered 1-42, labelled COPYRIGHT and with a white London Stereoscopic Company label. Images include many shots of HMS Discovery & HMS Alert in amongst ice floes, several native Inuit groups, on board the expedition vessels and in the settlement of Godhaven, including one of Hans Hendrik the native 'Esquimaux' dog driver employed by the 'Discovery' with his daughter and son on the upper deck of 'Discovery'. Also group portraits of expedition members, arctic views and landscapes, sledging parties and encampments. (See back cover illustration) Organised by the British Admiralty and led by Captain George Strong Nares, the expedition was commissioned as a voyage of scientific discovery and general exploration, with its major aim being the conquest of the North Pole. HMS Alert and HMS Discovery set sail from Portsmouth on May 29th 1875. The expedition failed to reach the North Pole yet significant scientific data was gathered, a farthest north was reached and a considerable portion of the north Greenland coast was mapped. However, four men were lost to frost bite and scurvy and although the initial welcome home was warm, the British press turned on Nares, branding the expedition a total failure and demanding answers for the loss of life. Although Nares was not to blame, (lime juice provided by the admiralty for the prevention of scurvy had been boiled into concentrate, thereby destroying the vitamin C) the vilification he suffered and the expedition as a whole, has meant that it has largely slipped into obscurity. Fortunately for us, Nares requested photographers for the expedition and George White, Assistant Engineer for Alert and Thomas Mitchell, Paymaster for Discovery were trained at the Army School of Photography in Chatham in the latest photographic processes. These two men took some of the earliest photographic images of polar exploration that set a precedent in the field of photography followed by later professionals like Herbert Ponting and Frank Hurley in recording the activities, achievements and polar landscapes for a wider audience at home. These fascinating early Arctic images were probably produced for lecture purposes and show us in excellent quality all manner of expedition details such as clothing, equipment, the parties' involved as well as some remarkable images of the indigenous Greenlanders. Condition report: Very good condition."
Link in previous post.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on November 08, 2016, 07:45:39 PM
Ice is forming in Nares Strait between the flowing floes, and gets broken up and carried down stream, just like in previous years at this time of year.  DMI's  (http://ocean.dmi.dk/arctic/kennedy.uk.php)Sentinel images show floes continue to be on the move from the Arctic just above Lincoln Sea all the way to Baffin Bay.  No floes appear to be large enough to get stuck anywhere, so continued ice export is probable.
Title: Re: The Nares Strait thread
Post by: Tigertown on November 09, 2016, 03:46:32 AM
Colors play tricks on my eyes, but is that not the thick MYI  that you are talking about flushing through?
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2F&hash=35d7d5d7526c9897dfb55501e320295a)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on November 28, 2016, 09:36:30 PM
A big floe is entering Nares Strait (vaguely outlined).  It appears to be breaking up as it approaches.  I doubt it will get stuck.  Image from DMI Sentinel-1 (http://ocean.dmi.dk/arctic/lincoln.uk.php).

Most of the Lincoln Sea continues to drain into Nares Strait.
Title: Re: The Nares Strait thread
Post by: be cause on November 28, 2016, 11:20:20 PM
Glad you posted Tor .. I have been watching Nares and Fram with the DMI . Can you or anyone direct me to other satellite images other than coastal Greenland ?

thanks in advance .. b.c.
Title: Re: The Nares Strait thread
Post by: oren on November 29, 2016, 06:17:41 AM
Glad you posted Tor .. I have been watching Nares and Fram with the DMI . Can you or anyone direct me to other satellite images other than coastal Greenland ?

thanks in advance .. b.c.
I am not an expert on the subject, but I think this should help you
https://worldview.earthdata.nasa.gov/ (https://worldview.earthdata.nasa.gov/)
Title: Re: The Nares Strait thread
Post by: johnm33 on November 29, 2016, 03:11:08 PM
"I am not an expert on the subject, but I think this should help you
https://worldview.earthdata.nasa.gov/ (https://worldview.earthdata.nasa.gov/)"
or
http://www.polarview.aq/arctic (http://www.polarview.aq/arctic)
Title: Re: The Nares Strait thread
Post by: charles_oil on December 01, 2016, 10:19:23 PM
Tor - many thanks for the above - I tried following the "Nares plug" on Sentinel-1 - it looks like its broken in half, entered the Nares straight, then withdrawn again !

The Nares plug is easier to see on:
http://ocean.dmi.dk/arctic/kennedy.uk.php, (http://ocean.dmi.dk/arctic/kennedy.uk.php,)

If someone could animate it... it would look great with the ebb and flow from 27th to 1st Dec!
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on December 05, 2016, 08:08:03 PM
That big floe at the Lincoln Sea/Robeson Channel demarcation (link for place names (http://forum.arctic-sea-ice.net/index.php/topic,277.msg5119.html#msg5119)) has certainly been dancing around these past several days!  I note a distinctive small floe in Hall Basin (off Petermann Glacier) has been dancing around as well.  Floes in Kane Basin are generally going southward (technically southwestward).

Floes are not moving very fast, and some days they hardly move at all.  The whole thing could just stop any day, especially if there are a couple of hardly-any-movement days (like Dec. 4 was in both Kane Basin and Robeson Channel).

I've not learned how to make a movie, but I open several DMI Sentinel images (http://ocean.dmi.dk/arctic/kennedy.uk.php) using the Ctrl key so that the different days open in separate tabs (rather than windows).  Clicking on subsequent images shows movement.  At times, I've placed a ruler on my computer screen to calculate how far floes moved.  (Petermann Glacier is 15 km wide (https://en.wikipedia.org/wiki/Petermann_Glacier), for a scale guide. [Conveniently, on my screen it is 15 mm wide!])
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on December 06, 2016, 05:02:54 PM
The big floe is fully within Robeson Channel today, per Polar View image (http://www.polarview.aq/images/106_S1jpgsmall/201612/S1A_EW_GRDM_1SSH_20161206T123204_555D_N_1.jpg).
Title: Re: The Nares Strait thread
Post by: be cause on December 10, 2016, 01:11:12 AM
The big floe is fully within Robeson Channel today, per Polar View image (http://www.polarview.aq/images/106_S1jpgsmall/201612/S1A_EW_GRDM_1SSH_20161206T123204_555D_N_1.jpg).
and has moved quickly south the last few days . An even bigger floe is approaching the entrance . Will it break up and enter the straight or is there still ice that can plug the Nares ?
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on December 11, 2016, 05:46:12 AM
Boy is it moving!   On the 8th the 'big floe' was opposite Petermann Glacier and today's image shows it is about to enter Kane Basin.  It split in two since the 8th, as well (attached image).

(Up north, the 'even bigger floe' is definitely approaching the Strait.) 
And according to windtv (https://www.windytv.com/?80.600,-61.875,5), the wind is mostly from the north along Nares Strait and will generally be stronger (and from the north) over the next week.
Title: Re: The Nares Strait thread
Post by: logicmanPatrick on December 11, 2016, 06:13:04 AM
(Up north, the 'even bigger floe' is definitely approaching the Strait.)

It won't last long.  In the image, green shows my take on the true current outline and blue shows where I think it will fracture soon.  The grey line is an artifact.

Original image source:
http://ocean.dmi.dk/arctic/kennedy.uk.php (http://ocean.dmi.dk/arctic/kennedy.uk.php)

Title: Re: The Nares Strait thread
Post by: TerryM on December 11, 2016, 08:29:29 AM
Could we have another 2009 with no ice bridge forming?


Terry
Title: Re: The Nares Strait thread
Post by: bairgon on December 11, 2016, 07:41:33 PM
Actually, it appears to have split length-wise. 2/3 of it has proceeded down Nares, with 1/3 blocking the gap.
 
Looking at the recent Lincoln photos at http://ocean.dmi.dk/arctic/lincoln.uk.php (http://ocean.dmi.dk/arctic/lincoln.uk.php) and in particular http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/20161211s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/20161211s01a.ASAR.jpg) shows a polynya of about 100km x 100km which has ice breaking off and flowing down the Nares. The bridge is already fractured length-wise, so it doesn't look like it will hold this flow.

Looking back through the Sentinel images shows this polynya starting to open on the 7th of December.

Edit: I've found a reference  here (http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?2005ESASP.572E.328G&defaultprint=YES&filetype=.pdf) which describes this polynya as a standard feature. This references a paper by Kozo, 1991 (preview here (http://onlinelibrary.wiley.com/doi/10.1029/91GL02574/epdf?r3_referer=wol&tracking_action=preview_click&show_checkout=1&purchase_referrer=www.google.co.uk&purchase_site_license=LICENSE_DENIED)), describing this polynya with a solid arch from Greenland to Ellesmere island, with an opening forming at the top of Nares. He says that the sea ice transport normally stops by January, so this pattern appears to be fairly normal - at the moment.
Title: Re: The Nares Strait thread
Post by: be cause on December 28, 2016, 06:48:26 PM
Nares is in full flow .. rate of passage today @ 7 days N to S . Rubble in .. mush out .
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 01, 2017, 05:21:15 AM
DMI's Lincoln Sea Sentinel images of 30-12-2016 and 31-12-16 show ice being drawn north out of the top of Nares Strait! And not much movement in most of Nares' length.  Windytv.com shows the winds today and yesterday (last two days of 2016) were from the South in the region, but will change to being from the North tomorrow (first day of 2017).
Title: Re: The Nares Strait thread
Post by: bairgon on January 10, 2017, 06:20:57 PM
Ice started flowing south again after about the 8th of Jan, once winds turned to the north. They look set to continue from the north for a while.

However, there is now a large floe which looks like it might block the mouth of the strait. The lead on the south-west has formed as it has blocked movement. However, there does appear to be a crack lengthwise which might cause complete breakup of the floe.

Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 10, 2017, 10:30:03 PM
Given the composite nature of, and cracks across, this large floe, I expect it will break or shatter upon being appropriately stressed and predict it will therefore not block Nares Strait.  (But my predictions are infamous!)
Title: Re: The Nares Strait thread
Post by: oren on January 10, 2017, 11:45:01 PM
The Arctic is throwing its best MYI reserves into the battle - that's a huge floe. I agree that it's expected to break up. Normally Nares should be holding on to its open state until February, and the Northern arch typically forms back in the Lincoln Sea and not right at the opening.
Title: Re: The Nares Strait thread
Post by: Wipneus on January 11, 2017, 02:43:53 PM
Need a stronger floe.
Title: Re: The Nares Strait thread
Post by: DrTskoul on January 11, 2017, 03:33:48 PM
Don't see any around.... :o
Title: Re: The Nares Strait thread
Post by: Gray-Wolf on January 11, 2017, 04:11:57 PM
Should we again run into fragmentation events across the basin will a Lincoln Sea still draining into Nares give 'wiggle room' for any movement of the fractured pack?
Title: Re: The Nares Strait thread
Post by: Shared Humanity on January 12, 2017, 04:27:46 AM
That floe is quite visibly made up of small MYI floes stitched together with FYI. It fractured easily from just the accelerating currents entering into Nares which can be seen by how the leading portion split and accelerated away from the trailing portion. I see absolutely no ice in that entire frame that is any different. There are simply no large MYI floes anywhere. I also see no evidence of an arch forming anywhere.
Title: Re: The Nares Strait thread
Post by: bairgon on January 12, 2017, 05:59:40 PM
I agree, I don't hold out much hope for a blockage there.

Having said that, the half that split off has now travelled about 10kms down Nares, but the other half has hardly moved, apart from appearing to get more firmly wedged. See http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20170112s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20170112s01a.ASAR.jpg)

The impending GAC will probably break this up, particularly as the wind is due to blow up the strait again starting on the 17th - see https://earth.nullschool.net/#2017/01/17/0000Z/wind/surface/level/orthographic=-51.72,82.27,1106/loc=-62.614,81.468 (https://earth.nullschool.net/#2017/01/17/0000Z/wind/surface/level/orthographic=-51.72,82.27,1106/loc=-62.614,81.468)
Title: Re: The Nares Strait thread
Post by: Wipneus on January 14, 2017, 08:25:57 AM
Breaking further, as needed.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 16, 2017, 03:14:10 PM
cross-posted... (Thanks A-Team for your high quality presentations!)
Storm analysis should marginally benchmark export through the Nares Strait. The focus usually is on the Fram and Svalbard-FJI front; for this storm, remarkable export out the Bering Strait is also anticipated by Hycom. (That will require clear weather on puffin-feeder imagery or low-res microwave as Sentinel-1AB rarely covers the Chukchi.)

Nares however proves quite astonishing -- the ice is cornering Ellesmere Island with a developing local coastal CAA current with a clear shear line peeling back ice to be exported from essentially stationary Lincoln Sea ice, the process seemingly accelerating in the last few days. DMI provides a daily series of Sentinel-1AB for the mouth of the Nares Strait, so an easily extensible storm monitoring template, so far for 01-14 Jan 17.

There has been clear weather recently and complimentary imagery with precision date stamps from NOAA AVHRR at DMI Lincoln in the full size image inset. These are not mosaics so subtracting UTC times then allows velocities as displacement in km / time between scenes in hours. However image geometry is slightly off co-registration.

The broader sweep along the CAA provided by DTU Saldo Sentinel-1AB mosaics shows the entire ice pack lifting off poleward, rather than garlic-pressing south. This process too seems to have picked up speed in the last 2-3 days. The gray wedges are gaps in mosaic coverage.

http://ocean.dmi.dk/arctic/nord.uk.php (http://ocean.dmi.dk/arctic/nord.uk.php) Lincoln series

Technical note: These are sub-optimal in contrast space, presented as RGB when in fact 7-bit grayscale (down from the original 16-bit). However they are correctly co-registered despite the land aspect flopping around with satellite viewing angle (being a mix of 1A and 1B). The interval between frames is not strictly 24 hours; timestamps are not provided.

After cropping to forum width, the 14 frames are tiled into 1 which is processed for adaptive contrast in ImageJ in one step and resliced back in gimp and saved with animation time delay of 140 ms. Unlike .mov a .gif  file can readily be downloaded and viewed locally for step-by-step analysis or run at a slower speed.

[Edit: go to the original A-Team post  (http://forum.arctic-sea-ice.net/index.php/topic,1611.msg99405.html#msg99405)for images.]
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 17, 2017, 03:54:31 PM
Floe breaking up on Hans Island. (Blue highlight should be on the island but isn't.  Purple 'circle' is the island.  (Purple dot is a mistake.)) Image from PolarView on 16-1-2017 (http://www.polarview.aq/images/105_S1jpgfull/S1A_IW_GRDH_1SSH_20170116T205031_004C_N_1.final.jpg).  For scale, the island is  (https://en.wikipedia.org/wiki/Hans_Island)1.3 km2 (0.5 sq mi), 1,290 metres (0.80 mi) long and 1,199 metres (0.745 mi) wide.
(https://upload.wikimedia.org/wikipedia/commons/c/ca/HansIsland.png)
Title: Re: The Nares Strait thread
Post by: bairgon on January 18, 2017, 08:35:29 PM
Floe breaking up on Hans Island.

That has suffered rather a lot in the GAC. Flow of the floes has reversed - compare 17th and 18th Jan pics from http://ocean.dmi.dk/arctic/kennedy.uk.php (http://ocean.dmi.dk/arctic/kennedy.uk.php).

Current state of the floe:

Title: Re: The Nares Strait thread
Post by: logicmanPatrick on January 19, 2017, 10:31:18 PM
These images from some of my older blog posts may be of interest.

Image 1 shows, in red, locations where an ice bridge has formed in the past.  Please note that the arc often seen in the Lincoln Sea is not a true ice bridge, although it shows some of the same dynamic behaviour.
http://www.science20.com/chatter_box/arctic_tipping_points_4_broken_bridges_nares (http://www.science20.com/chatter_box/arctic_tipping_points_4_broken_bridges_nares)

Image 2 shows the formation of the Kane Basin ice bridge in February 2011.
http://www.science20.com/chatter_box/arctic_ice_april_2011-78127 (http://www.science20.com/chatter_box/arctic_ice_april_2011-78127)

This may also be of interest: Bridges that build themselves
http://www.science20.com/chatter_box/bridges_build_themselves (http://www.science20.com/chatter_box/bridges_build_themselves)
Title: Re: The Nares Strait thread
Post by: solartim27 on January 24, 2017, 05:22:48 PM
A bridge has formed in Kane, held together from the 21st to 23rd.  Doesn't look very strong to me.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 24, 2017, 09:23:08 PM
Temporary bridge has broken - see today's DMI Kane Basin  (http://ocean.dmi.dk/arctic/kane.uk.php)- Sentinel.  It "looked" good yesterday!  Winds next week, per Windtv (https://www.windytv.com/?2017-01-31-12,80.449,-65.896,5), will be intense!
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 24, 2017, 09:35:06 PM
Today starts a new chipping away at what looks like a bridge (but probably isn't) at the top of Nares Strait.
Title: Re: The Nares Strait thread
Post by: oren on January 24, 2017, 10:18:48 PM
Thanks for the updates Tor.
This is basically on schedule. Last year the southern bridge first held on January 29th. Interesting if this year's warmer temps will cause a delay due to lower tensile strength of the ice, although the Lincoln Sea ice (being MYI) should be less affected by one season's conditions.
Title: Re: The Nares Strait thread
Post by: johnm33 on January 25, 2017, 12:57:34 AM
With a new moon on saturday it'll be at least 10 days before it settles down again. I'm curious to see just how much the tides break up the Lincoln sea end.
Title: Re: The Nares Strait thread
Post by: Wipneus on January 25, 2017, 06:42:43 PM
The arch in the Kane basin did not hold. The one on the other side it is still there, it lost a peeling though.
Title: Re: The Nares Strait thread
Post by: bairgon on January 25, 2017, 09:59:55 PM
But here we go again. The wind is blowing from the SW again, and the peeling is being pushed back. A later picture is below.

Nullschool shows wind up the strait for the next few days. Maybe this time it will build a bridge?
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 26, 2017, 04:53:04 PM
The largest part of the floe that crumbled when hitting Hans Island on the 16th, and then got blown back northwards, is now back beside Hans Island (on the other side of Hans O. and 'upside-down')!  (2nd image from Polar View (http://www.polarview.aq/arctic).)
Title: Re: The Nares Strait thread
Post by: A-Team on January 26, 2017, 06:27:36 PM
Below are the Sentinel-1AB time series for the Nares for 01-25 Jan 2017. These were made the easy way using the ability of ImageJ to chase down and compile a stack of urls (provided those end in an image tag such as jpg, tif, png etc) ready for stack-level cropping, rotating, and exporting as forum-ready gif.

Nares comes as a 37º diagonal so it is best to rotate CW to make best use of the 700 pixel forum constraint while retaining full resolution. Sentinels benefit from an adaptive contrast improvement (CLAHE command set at 64 pixel boxes at 1.65 slope).

Note a layer of upper arch peeling away in the last two frames.

There is no need to understand anything about ImageJ. Simply acquire and open File --> Import --> Stack from List... and point it at your previously compiled plain text file of urls. These are named and stored systematically (though variantly) at most sites. After competing stack operations, save as 'Animated Gifs...' with looping and an appropriate time delay between frames. Exit ImageJ, file is now ready for upload to the forum (or more reprocessing in gimp).

The DMI Greenland case is shown below; here just the Sentinels were wanted. For just 1A or just 1B use the 11th character in the file name as a sort field.

For Sentinel etc we don't know whether or not there will be an image taken tomorrow or some day next week. However it doesn't matter to ImageJ: if the image isn't available, it simply inserts an all black layer in the stack. Thus a rolling request window solves the auto-updating problem.

Sites like AMSR2, ADS-Jaxa, SMOS,... work very similarly. There are some resources however that don't display the source url or don't allow access to the archive folder hierarchy.

http://ocean.dmi.dk/arctic/kennedy.uk.php (http://ocean.dmi.dk/arctic/kennedy.uk.php) entry to DMI database
http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/ (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/) where the files are listed

Tabs and sort field need to be removed:

http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/ (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/)   20170120s01b.ASAR.jpg   b
http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/ (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/)   20170122s01a.ASAR.jpg   a
http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/ (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/)   20170122s01b.ASAR.jpg   b
http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/ (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/)   20170123s01a.ASAR.jpg   a
http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/ (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/)   20170123s01b.ASAR.jpg   b
http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/ (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/)   20170124s01a.ASAR.jpg   a
http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/ (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/)   20170124s01b.ASAR.jpg   b
http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/ (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/)   20170125s01a.ASAR.jpg   a
http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/ (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/)   20170125s01b.ASAR.jpg   b
Title: Re: The Nares Strait thread
Post by: Wipneus on January 30, 2017, 12:44:23 PM
No, does not hold, go for a bigger arch?
Title: Re: The Nares Strait thread
Post by: bairgon on January 30, 2017, 01:41:57 PM
It's what is to be expected.

Nullschool shows winds helping the ice along for at least 4 days, so we could see a big area opening up in Lincoln Sea again.

I wonder if it's going to reach through to the line of moving ice across the top of Ellesmere and Greenland?
Title: Re: The Nares Strait thread
Post by: Wipneus on February 02, 2017, 08:29:00 AM
The arch keeps peeling off, each time leaving a bigger arch.
Title: Re: The Nares Strait thread
Post by: Adam Ash on February 02, 2017, 09:06:25 AM
To my eye, the 'arch' does not seem to have any structural integrity itself - its not resisting movement of anything towards the straight.

Rather the arch-shaped features seem to be created by a northbound push emanating from Nares Straight.  The loss of portions of the arch seem to be rebound events from a northbound swell or tidal race from the straight, rather than a collapse of a structurally-stressed arch. 

??
Title: Re: The Nares Strait thread
Post by: oren on February 02, 2017, 12:18:23 PM
To my eye, the 'arch' does not seem to have any structural integrity itself - its not resisting movement of anything towards the straight.

Rather the arch-shaped features seem to be created by a northbound push emanating from Nares Straight.  The loss of portions of the arch seem to be rebound events from a northbound swell or tidal race from the straight, rather than a collapse of a structurally-stressed arch. 

??
The ice seems to be weak indeed. However, I doubt that the push is northbound. The ice beyond the "arch" is stationary, while the ice peeling off is carried towards the strait.
Title: Re: The Nares Strait thread
Post by: logicmanPatrick on February 02, 2017, 12:45:09 PM
The arc (sic) in the Lincoln Sea is not an ice arch.  It is usual to see a Lincoln Sea polyna.  Less usual is an ice arch just inside the Nares Strait.

Although ice arches normally form by about April, I don't expect to see one form this year: the ice is too thin, weak, young and mobile.
Title: Re: The Nares Strait thread
Post by: johnm33 on February 02, 2017, 12:55:34 PM
Adam Ash
 "Rather the arch-shaped features seem to be created by a northbound push emanating from Nares Straight.  The loss of portions of the arch seem to be rebound events from a northbound swell or tidal race from the straight, rather than a collapse of a structurally-stressed arch.

??"
The tidal surge north seems to be hugging and undermining the ellesmere side but is inhibited by the opposing wind, the ebb tide however is accelerated. Looks to me like the ellesmere side will collapse in a day or two.
Title: Re: The Nares Strait thread
Post by: Tigertown on February 02, 2017, 02:06:42 PM
@johnm33
I Agree. 3 meter waves can be seen in the lower part of the Strait, where there is a clearing. Check
here https://earth.nullschool.net/#current/ocean/primary/waves/overlay=significant_wave_height/orthographic=-80.78,76.84,3000/loc=-73.403,76.412
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on February 02, 2017, 05:04:56 PM
Ice in the upper Nares Strait is certainly moving right along.  Following images are from January 30 and 31 and February 1.  A readily identified floe has a purple dot added.  For scale: Petermann Fjord is 22 km wide (lower left on these screenshots). (Jan. 30 image is the lowest of 3 images; Feb. 1 image is 'on top' - they are mis-labeled - woops.)
Title: Re: The Nares Strait thread
Post by: ghoti on February 02, 2017, 05:46:45 PM
The consensus of the various ice thickness products seems to suggest the ice in the Lincoln Sea is 4m thick. Looking at the rate of breakup and flow rates south through the Nares makes that seem unlikely.

Can 4m thick ice really shatter so easily and flush out the strait?
Title: Re: The Nares Strait thread
Post by: DrTskoul on February 02, 2017, 06:06:44 PM
Yes if is chunks of 4 m I've glued by first and second year ice. Strength will be this compromised.
Title: Re: The Nares Strait thread
Post by: johnm33 on February 02, 2017, 07:38:32 PM
There's a good series of images on polarview from about noon today showing almost the whole strait, this one http://www.polarview.aq/images/106_S1jpgsmall/201702/S1B_IW_GRDH_1SSH_20170202T120025_23E5_N_1.jpg (http://www.polarview.aq/images/106_S1jpgsmall/201702/S1B_IW_GRDH_1SSH_20170202T120025_23E5_N_1.jpg) from the southern end has the signature of internal waves caused by the full flood of the ebbing tide.
Title: Re: The Nares Strait thread
Post by: oren on February 05, 2017, 12:27:19 AM
For the last three days (2/2 - 4/2) the "arch" at the Lincoln Sea seems to be stationary. Will this stability prove to be long-lived? Past experience this month says no, the date says maybe yes.
Title: Re: The Nares Strait thread
Post by: oren on February 05, 2017, 06:55:04 PM
Candidate Lincoln arch proposed. Sentinel animation from Jan 29 to Feb 5.
Title: Re: The Nares Strait thread
Post by: DrTskoul on February 05, 2017, 07:20:13 PM
Candidate Lincoln arch proposed. Sentinel animation from Jan 29 to Feb 5.

That's no arch. A melangerie of ice chunks....
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on February 08, 2017, 05:37:12 PM
As best I can tell from DMI Sentinel images, there is virtually no Arctic Ocean ice in Nares Strait north of Kane Basin.  Nothing has peeled off of the Lincoln Sea 'bridge' since about February 1.  A floe that broke off on Jan. 30 or 31 is in southern Kane Basin.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on February 09, 2017, 04:15:02 AM
"As best I can tell" (where did I just read that phrase?), comparing the DMI Sentinel images (http://ocean.dmi.dk/arctic/lincoln.uk.php) dated 7/2 and 6/2 (both showing part of the Lincoln Sea bridge), there is a tiny amount of movement on the southern (eastern) side of the Sea, but none in the middle part.  This might not be 'real' (only an artifact of the technologies used), but it bears watching.  The 'half-white' floe whose images I once marked with purple dots is about to exit Nares Strait, so about 10 days to go the whole way.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on February 09, 2017, 08:46:48 PM
I'm pretty sure what I see is an artifact and not movement.

I don't think I've seen Nares Strait so free of floes!

This next week will see mostly winds out of the south, according to Windytv (https://www.windytv.com/?2017-02-17-00,82.288,-45.044,5).  Next Thursday and Friday shows strong winds.

Will these southerly winds break the week-old arch in the Lincoln Sea?
Title: Re: The Nares Strait thread
Post by: johnm33 on February 09, 2017, 11:23:57 PM
I'm thinking the Ellesmere side won't last past sunday, after that it depends on the winds which are very changeable.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on February 10, 2017, 05:43:55 PM
The identified floe is now in Baffin Bay, as of February 9: 10 days to go 500 km (50 km/day or 0.6 m/s or 1.2 mph)
Title: Re: The Nares Strait thread
Post by: Wipneus on February 11, 2017, 06:01:37 PM
Still there.
Title: Re: The Nares Strait thread
Post by: DrTskoul on February 11, 2017, 06:22:55 PM
Amazing....
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on February 11, 2017, 06:52:37 PM
Windytv (https://www.windytv.com/?81.891,-60.018,6) forecasts strong southerly winds (> 30 kt) in the Lincoln Sea area most of Monday and on Thursday-Friday.  Those are the next 'make-it-or-break-it (https://www.google.com/search?q=make+it+or+break+it&ie=utf-8&oe=utf-8#q=make+it+or+break+it+meaning)' times to watch.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on February 12, 2017, 02:05:35 AM
At first glance it looks like the Lincoln Sea ice arch sloughed some ice, but it didn't happen.  Below are screenshots from Feb. 11 (suggesting the ice movement) and the 10th showing there wasn't any.
Title: Re: The Nares Strait thread
Post by: Wipneus on February 21, 2017, 08:22:24 AM
Arch is holding, gets an inner arch from new formed ice.
Title: Re: The Nares Strait thread
Post by: Shared Humanity on February 21, 2017, 03:22:12 PM
Although that inner arch looks fragile.
Title: Re: The Nares Strait thread
Post by: Adam Ash on February 23, 2017, 06:54:23 AM
There is no sign of the main arc being pushed into / snuggled up to by the general pack ice at all over these animations.  The main pack is just sitting there.  So the arc is not resisting movement towards Nares, rather the clearer water between Nares and the main arc defining the edge of the pack ice is like a prop wash from Nares which peters out as it expands into the main pack area. 
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on February 28, 2017, 06:51:03 PM
This DMI image shows the transverse fault [purple arrows] (remember, natural ice is a monomineralic rock) protecting the Lincoln Sea (plus some) ice from the tossed and turned (fractured) Arctic. Sometimes the equivalent fault line is further south, more nearly on the edge of the Lincoln Sea.  (And sometimes all the ice is fractured.)
Title: Re: The Nares Strait thread
Post by: Shared Humanity on March 01, 2017, 05:54:58 AM
All of the ice looks like rubble.
Title: Re: The Nares Strait thread
Post by: bairgon on March 01, 2017, 07:27:27 AM
Although that inner arch looks fragile.

The inner arch has collapsed - see image below from 27/02/2017. This is also visible in Tor's image.

There was some ice to the north-west of the strait which has separated as well. Nullschool shows winds going up the strait for a while on 26/02, but not particularly strong. Very cold. https://earth.nullschool.net/#2017/02/26/1500Z/wind/surface/level/overlay=temp/orthographic=8.93,84.97,3000/loc=-61.715,81.906 (https://earth.nullschool.net/#2017/02/26/1500Z/wind/surface/level/overlay=temp/orthographic=8.93,84.97,3000/loc=-61.715,81.906)

Arch is holding, gets an inner arch from new formed ice.

Was there a foehn wind locally? There were winds up the strait from 12th to 17th, much stronger and warmer than the 26th, which seemed to have the effect of forming the inner arch (see message quoted above). Why should the relatively low winds on the 26th break the arch and also cause the ice to separate from the north of the strait?

Image link: http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20170227s01a.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20170227s01a.ASAR.jpg). See http://ocean.dmi.dk/arctic/kennedy.uk.php (http://ocean.dmi.dk/arctic/kennedy.uk.php) to browse images.



Title: Re: The Nares Strait thread
Post by: Tigertown on March 01, 2017, 08:01:29 AM
@bairgon
 There have been these terrible storms SE of Greenland that have made giant waves locally and stirred up smaller ones at greater distances. Add to that  the area where Baffin and Nares meet being susceptible to wave activity, it is not unreasonable to think that upwelling warmer water has eroded away at this arch area for a while now. But beyond that it seems that the ice is really breaking down all over the Arctic right now without any one outstanding event to blame.
Title: Re: The Nares Strait thread
Post by: johnm33 on March 01, 2017, 11:47:03 AM
" Why should the relatively low winds on the 26th break the arch and also cause the ice to separate from the north of the strait?" Tides force a current north on the west/south side of the strait, these undermine the fast ice on the arctic coast of Ellesmere. When the tide turns a surge of water tends to flow down the Greenland side, the size of the new ice 'crescents' breaking off indicate the interuptions to the overwhelmingly southern flow. Given some of the powerful winds going up or down the strait, i'm a little surprised that the big arch has held out.
Title: Re: The Nares Strait thread
Post by: charles_oil on March 01, 2017, 01:44:41 PM
I could not help but think of the flimsy looking arch at Nares when I saw this one !  Amazingly its got greenery sprouting so has lasted a while.
Title: Re: The Nares Strait thread
Post by: DrTskoul on March 01, 2017, 01:54:03 PM
I could not help but think of the flimsy looking arch at Nares when I saw this one !  Amazingly its got greenery sprouting so has lasted a while.

While everything around it crumbled !!
Title: Re: The Nares Strait thread
Post by: bairgon on March 05, 2017, 07:20:18 PM
Looks like the arch has started to go. Following is from https://worldview.earthdata.nasa.gov/?p=arctic&l=Land_Mask,MODIS_Aqua_Brightness_Temp_Band31_Night(palette=rainbow_1,min=232.5,max=280.6,squash)&t=2017-03-05&z=3&v=-445418.27928883245,-903459.91041024,46101.72071116755,-651299.91041024 (https://worldview.earthdata.nasa.gov/?p=arctic&l=Land_Mask,MODIS_Aqua_Brightness_Temp_Band31_Night(palette=rainbow_1,min=232.5,max=280.6,squash)&t=2017-03-05&z=3&v=-445418.27928883245,-903459.91041024,46101.72071116755,-651299.91041024)

Not visible on Kennedy at dmi yet - http://ocean.dmi.dk/arctic/kennedy.uk.php (http://ocean.dmi.dk/arctic/kennedy.uk.php)
Title: Re: The Nares Strait thread
Post by: crandles on March 05, 2017, 07:28:41 PM
Not visible on Kennedy at dmi yet - http://ocean.dmi.dk/arctic/kennedy.uk.php (http://ocean.dmi.dk/arctic/kennedy.uk.php)

Looks visible on NOAA 14:45 5 Mar to me
Title: Re: The Nares Strait thread
Post by: J Cartmill on March 05, 2017, 08:45:51 PM
You can see it on the NPP Suomi on worldview as well.




https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,VIIRS_SNPP_DayNightBand_ENCC,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-03-05&z=3&v=-396928.00000000006,-879104,-47232.00000000006,-715776 (https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,VIIRS_SNPP_DayNightBand_ENCC,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-03-05&z=3&v=-396928.00000000006,-879104,-47232.00000000006,-715776)


Title: Re: The Nares Strait thread
Post by: Tor Bejnar on March 05, 2017, 11:51:50 PM
Screenshot from PolarView (http://www.polarview.aq/arctic): we see the broken off floe clearly.  The rest of the bridge looks okay, I think.

Title: Re: The Nares Strait thread
Post by: oren on March 06, 2017, 12:02:24 AM
After intense cold and holding in place for a month, this breakage is unusual as far as I know. Now that it did happen, I would expect more pieces to follow suit.
Title: Re: The Nares Strait thread
Post by: Gray-Wolf on March 06, 2017, 10:01:59 AM
The condition of that broken off floe is obviously a worry! It is just a conglomeration of old bits and bobs glued together with FY ice. How you can even begin to figure its structural integrity escapes me!!
Title: Re: The Nares Strait thread
Post by: Shared Humanity on March 06, 2017, 03:20:33 PM
The condition of that broken off floe is obviously a worry! It is just a conglomeration of old bits and bobs glued together with FY ice. How you can even begin to figure its structural integrity escapes me!!

And the portion of ice that it separated from looks even worse. Would not be surprised if the whole thing gave way. What kinds of winds are we expecting to see? Anything strong down the strait?
Title: Re: The Nares Strait thread
Post by: bairgon on March 06, 2017, 03:55:00 PM
And the portion of ice that it separated from looks even worse. Would not be surprised if the whole thing gave way.

That's what was said 1 month ago....

That's no arch. A melangerie of ice chunks....

... and it is only just now showing signs of weakness. Winds aren't particularly strong. Temperature is low, so perhaps it's cemented together fairly well.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on March 10, 2017, 06:29:32 PM
This "visible spectrum" DMI image (http://ocean.dmi.dk/arctic/kennedy.uk.php) of the Kennedy Channel (from yesterday) sure shows the streaming of clouds (fog?) over the strait!
Title: Re: The Nares Strait thread
Post by: johnm33 on March 12, 2017, 03:28:56 PM
From http://go.nasa.gov/2lQwFfp (http://go.nasa.gov/2lQwFfp) [11th] the arcs looking fragile
(https://puu.sh/uFxrC/d0c541d628.jpg)
Title: Re: The Nares Strait thread
Post by: Cate on March 12, 2017, 10:15:14 PM
It doesn't look very much like an arc(h) anymore.

http://www.arctic.io/explorer/4Xa5A/2017-03-11/9-N82.28114-W62.21348 (http://www.arctic.io/explorer/4Xa5A/2017-03-11/9-N82.28114-W62.21348)
Title: Re: The Nares Strait thread
Post by: mati on March 12, 2017, 11:21:33 PM
It's the MUMMY's foot stomping on the arctic ice
nooooooooooooooooooooooooo,,,...
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on March 13, 2017, 01:22:40 AM
Screen print from today's PolarView (http://bslmagb.nerc-bas.ac.uk/iwsviewer/?image=DataPolarview/111_S1jpeg2000_201703/S1B_EW_GRDM_1SSH_20170312T195239_CAD1_N_1.8bit.jp2) shows the floes (one quite small) that broke off a few days ago, and the foot bridge [sorry about that] looking good.
Title: Re: The Nares Strait thread
Post by: Shared Humanity on March 13, 2017, 02:22:57 PM
If that's a foot, the poor bastard has flat feet, otherwise known as a fallen arch.

Doubly sorry about that.  ::)
Title: Re: The Nares Strait thread
Post by: DrTskoul on March 13, 2017, 02:52:53 PM
The attack of the puns.....
Title: Re: The Nares Strait thread
Post by: bairgon on March 13, 2017, 08:31:59 PM
Is there another arch forming further down Nares? With winds from the south-west and cold temps this one might hold.

https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-03-13&z=3&v=-817714.7138936454,-1204214.1471225694,-326194.71389364544,-952054.1471225694&ab=off&as=2017-03-04&ae=2017-03-13&av=1&al=false (https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-03-13&z=3&v=-817714.7138936454,-1204214.1471225694,-326194.71389364544,-952054.1471225694&ab=off&as=2017-03-04&ae=2017-03-13&av=1&al=false)

Title: Re: The Nares Strait thread
Post by: bairgon on March 13, 2017, 08:38:19 PM
For reference - a photo of Nares taken on March 10th (click title):

NASA Ice: Photo from yesterday's #IceBridge flight: View across the Nares Strait from Greenland to Ellesmere Island, Canada.
https://twitter.com/nasa_ice/status/840614419767918594
Title: Re: The Nares Strait thread
Post by: Shared Humanity on March 13, 2017, 10:20:35 PM
An arch commonly forms there and you are right, definitely an arch.
Title: Re: The Nares Strait thread
Post by: Neven on March 14, 2017, 12:03:35 AM
Yes, that looks more like it. I wonder how long it will hold, given how late it has formed. But these arches can sometimes hold on longer than expected.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on March 15, 2017, 04:06:21 PM
Comparing DMI Sentinel images from the 14th and the 12th, I see the arch holding steady, but there was ice movement in the central and upper parts of Kane Basin. 

Years ago I recall watching a slow gyre in Kane Basin while a bridge kept all the ice within the basin.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on March 17, 2017, 06:00:09 PM
The March 16 PolarView of Kane Basin (http://bslmagb.nerc-bas.ac.uk/iwsviewer/?image=DataPolarview/111_S1jpeg2000_201703/S1B_EW_GRDM_1SDH_20170316T205700_05C2_N_1.8bit.jp2) looks more ominous.  There are new cracks radiating from the Canadian side (not in March 15 image (http://bslmagb.nerc-bas.ac.uk/iwsviewer/?image=DataPolarview/111_S1jpeg2000_201703/S1B_EW_GRDM_1SDH_20170315T120803_D0BF_N_1.8bit.jp2)) and a single crack going southward from the ice bridge's northern edge (in the central part of Kane Basin).

Arches and bridges can be self-healing, of course, so I don't know if this one will survive or not.
Title: Re: The Nares Strait thread
Post by: bairgon on March 18, 2017, 06:24:18 PM
Looks like it's given way:

Title: Re: The Nares Strait thread
Post by: DrTskoul on March 18, 2017, 06:46:09 PM
Oh well....
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on March 20, 2017, 05:55:14 PM
Ice has flowed southward about 20 km in two days, per these DMI Kane Basin (http://ocean.dmi.dk/arctic/kane.uk.php) Sentinel images.  There is not a bridge across Kane Basin anymore.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on March 20, 2017, 06:48:31 PM
Yesterday's MODIS (https://lance.modaps.eosdis.nasa.gov/imagery/subsets/?subset=Arctic_r03c02.2017078.terra.250m) of lower Kane Basin shows the snow-covered ice moving en masse.  (Ignore the artifact!)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on March 20, 2017, 06:56:54 PM
At Nares' north end (through the clouds): the Lincoln Sea 'foot' appears to be forming an arch (that is, it's looking less flat footed).
Title: Re: The Nares Strait thread
Post by: Cate on March 20, 2017, 07:30:33 PM
The whole strait looks loosened up to me, like it's getting ready to move. Heading south through the strait from our giant foot----to the area just above the "knee", roughly at the mouth of Petermann, there is open water.

As usual, toggle the years to compare.

http://www.arctic.io/explorer/4Xa5A/2017-03-18/8-N81.71718-W64.88272 (http://www.arctic.io/explorer/4Xa5A/2017-03-18/8-N81.71718-W64.88272)
Title: Re: The Nares Strait thread
Post by: Cate on March 21, 2017, 12:53:12 PM
Some cloud cover on this 20 Mar 2017 image but it looks like there is even more open water in the Petermann outlet area than a couple of days ago.

This is only my second melt year and I don't use anything but Explorer, so maybe the other image sources and more experienced eyes have better info, please? but it looks to me like Nares ice is on the move. If so---well, it's a bit early, isn't it?

The link shows the entire strait. Zoom in for detail.

http://www.arctic.io/explorer/4Xa5A/2017-03-20/8-N80.53307-W68.45532 (http://www.arctic.io/explorer/4Xa5A/2017-03-20/8-N80.53307-W68.45532)
Title: Re: The Nares Strait thread
Post by: oren on March 21, 2017, 01:26:58 PM
...it looks to me like Nares ice is on the move. If so---well, it's a bit early, isn't it?
In the last couple of years the Strait opened up in early July.
However, the importance of Nares lies in its export of the thickest arctic sea ice that piles up in the Lincoln Sea. As long as one of the arches holds, the ice moving through the strait is mostly thin ice that will melt anyway later. And at this time of year there might even be refreezing of the resulting open water, depending on the weather. As of now, the northern arch still holds firmly. However, having just one arch increases the risk of an early totally-open strait, especially as the northern arch is less stable than the Kane basin arch due to its large width.

btw the easiest Nares resource is http://ocean.dmi.dk/arctic/kane.uk.php (http://ocean.dmi.dk/arctic/kane.uk.php) and/or http://ocean.dmi.dk/arctic/lincoln.uk.php (http://ocean.dmi.dk/arctic/lincoln.uk.php). Filtering by Sentinel images gives daily hi-res images (which are very easy to animate as they are co-located).
Title: Re: The Nares Strait thread
Post by: Cate on March 21, 2017, 01:35:20 PM
oren, yes, that giant jackboot is still holding in the Lincoln Sea. As for the strait freezing and thawing, agreed, to be expected this time of year, and I think evident in the image today as well, a thin ice skim between thicker floes. We are now at 12 hours daylight and increasing daily, so if Nares loses ice cover/albedo, I suppose that might make a tiny difference in the surface temp, which could knock on in ice-melt farther north in the passage?

Thanks for the image sources, will have a look.
Title: Re: The Nares Strait thread
Post by: Cate on March 24, 2017, 01:48:24 PM
http://www.arctic.io/explorer/4Xa5A/2017-03-23/7-N79.9726-W66.63132 (http://www.arctic.io/explorer/4Xa5A/2017-03-23/7-N79.9726-W66.63132)

oren, refreeze has happened, as you indicated---the heel, toe, and sole of the bigfoot boot in the Lincoln Sea appear to have frozen over again, for now. That arch seems to be key to keeping the older sea ice in place since there's not much fast ice farther down the strait for arch-formation. It's all on the move---the ice all down the strait appears to be cracking and moving. I assume this is current-driven?
Title: Re: The Nares Strait thread
Post by: oren on March 24, 2017, 10:19:56 PM
Yes, there is an almost-constant current flowing from the Lincoln sea to Baffin bay, I seem to remember it's being driven by surface height differences, but people on this forum could shed more light on this. I also found this image on the net which might help a bit.
(https://i1.wp.com/oceanbites.org/wp-content/uploads/2015/02/Untitled2.png)
Title: Re: The Nares Strait thread
Post by: Cate on March 24, 2017, 10:39:39 PM
Cool image, oren. Thanks so much.

Here is an interesting piece on wind and currents in Nares, by a student of Andreas Muenchow.

https://icyseas.org/2012/07/27/currents_winds_nares_strait_ice_arches/
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on March 26, 2017, 05:16:15 AM
The (virtually) only pieces of Arctic Ocean ice in Nares Strait, the ones that broke off the "foot" bridge in Lincoln Sea on March 5 (or very shortly before) are now off Petermann Fjord. (roughly 120 km in 20 days - the previous identifiable floe went Nares' entire 500 km in 10 days!)  (From 3/23 Polar View (http://bslmagb.nerc-bas.ac.uk/iwsviewer/?image=DataPolarview/111_S1jpeg2000_201703/S1B_IW_GRDH_1SSH_20170323T204949_9426_N_1.8bit.jp2).)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on March 29, 2017, 03:58:48 PM
On March 27, DMI Sentinel (http://ocean.dmi.dk/arctic/kennedy.uk.php) shows the larger floe about 20 km 'south' of Petermann Fjord and on March 28 shows it to be opposite Petermann Fjord!  Windytv (https://www.windytv.com/?2017-03-30-12,80.543,-62.139,5) shows winds are currently from the south.  (I confirmed this ice movement with PolarView (http://www.polarview.aq/arctic) - no image included.)

We could try to guess which end of Nares Strait it will exit (first) and when!
Title: Re: The Nares Strait thread
Post by: oren on March 29, 2017, 05:41:17 PM
I am wondering if a strong wind from the south can somehow break the Lincoln "arch". For now it looks to be frozen solid, but as the whole area of thick ice north of Greenland is currently cracking badly and flowing towards the Fram, except for the Lincoln Sea area directly adjacent to Nares, it means that there is a risk that cannot be discounted. And I assume the main strength of the arch is against stresses towards Nares, less so for stresses in the opposite direction.
Title: Re: The Nares Strait thread
Post by: Cate on March 30, 2017, 06:39:31 PM
Today (March 29) on Explorer, you can click back to 2014 in clear weather. Compared to previous years, the ice is almost all rubble, and any smooth ice is riven with cracks. There is no sign yet of the development of a strong arch in the strait, like 2014-2016, apart from the jackboot in the Lincoln.
Title: Re: The Nares Strait thread
Post by: Wipneus on April 01, 2017, 09:20:21 AM
Posting this in this thread, ice (arch) in the Lincoln Sea is often discussed and Nares Strait gets a mention.

From ESA's Space in Images (http://www.esa.int/spaceinimages/Images/2017/03/Alert_Canada):

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fwww.esa.int%2Fvar%2Fesa%2Fstorage%2Fimages%2Fesa_multimedia%2Fimages%2F2017%2F03%2Falert_canada%2F16881458-1-eng-GB%2FAlert_Canada_node_full_image_2.jpg&hash=e9e42bbf9ea9ddf68c670f129633d253)

Three Sentinel-1 images separted by a few months are combined as a RGB image showing the build-up of the ice pack.
Title: Re: The Nares Strait thread
Post by: Shared Humanity on April 01, 2017, 02:05:57 PM
Where some of the thickest MYI should reside, I am bothered by the broken up flows. Is that normal?
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on April 03, 2017, 03:55:45 AM
On 3/28 the floe from the 'foot' bridge was opposite Petermann Fjord.  Now it it 40 km "upstream" (northwards), as of today's DMI Sentinel (http://ocean.dmi.dk/arctic/kennedy.uk.php) image.

The forecast winds this coming week show mostly winds out of the south, so the floe will likely stay where it is for a while.  I suspect the 'Nares Strait born' ice around it will prevent much movement northwards.  Further south, it does not appear a new arch is forming anywhere, so 'as soon as' the winds shift, (virtually) the entire Nares Strait should flush out again, as it did in early February.

So, how thick has the "Nares Strait born" ice grown during these two months?  If it has remained -30oC for these two months (https://nsidc.org/cryosphere/seaice/processes/thermodynamic_growth.html), it could be a meter thick!
Title: Re: The Nares Strait thread
Post by: Jim Hunt on April 03, 2017, 09:04:52 AM
It could be a meter thick!

Not according to SMOS!

http://GreatWhiteCon.info/2017/04/facts-about-the-arctic-in-april-2017/#Nares (http://GreatWhiteCon.info/2017/04/facts-about-the-arctic-in-april-2017/#Nares)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on April 03, 2017, 06:48:15 PM
That "1 m" Nares Strait ice thickness was based on -30º C "constant for 2 months" (starting with basically no ice as most of the "old" ice was flushed out and no insulating snow [whose presence is obvious from MODIS images]).  Using DMI's FFD for 80N (an area that includes Kennedy Channel in Nares Strait, but is strongly influenced by the area north of 85N) between Feb. 1 and Apr. 1 [FDD=1250] , the formula from NSIDC (https://nsidc.org/cryosphere/seaice/processes/thermodynamic_growth.html)
            Thickness (cm) = 1.33 * FDD (°C)0.58
returns 83 cm.   I do not know if it has been colder or warmer in Nares Strait/Kennedy Channel than at the North Pole, but this is certainly seems to me to be a reasonable estimate.
Title: Re: The Nares Strait thread
Post by: crandles on April 03, 2017, 07:17:54 PM
SMOS does indicate some ice over 50cm (and even if it didn't, that wouldn't invalidate 'if cold, for 2 months then ...' logic presented).
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on April 03, 2017, 08:28:26 PM
What surprises me is the 1.2-2 m thick ice (according to the March 3 to 30 CPOM CryoSat-2 map Jim Hunt referenced [GreatWhiteCon (http://greatwhitecon.info/wp-content/uploads/2017/04/Cryosat_28_20170330.png)]) in the western (still flowing, albeit slowly) part of Kane Basin and in Smith Sound.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on April 07, 2017, 05:55:12 PM
cross post (there was some discussion about southern Baffin Bay ice in another thread, so I put this observation/question there):
I'm curious about the effect Nares Strait is having on Baffin Bay.  Specifically, Kane Basin (and the entire Strait) has not had an effective ice arch all winter, so Nares it has exported a lot of up-to-about-one-meter-thick (grown in Nares Strait) ice.  The volume (not thickness) of ice created in Nares Strait will be much greater than usual, as new ice with no snow cover is (virtually) continually being created in the northern parts of the Strait, and the first 10 or 50 cm grows much faster (in a given temperature) than the third.  And it is almost constantly being exported to Baffin Bay.
An edited and extended note can be found at
in the "2017 sea ice area and extent data" thread.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on April 09, 2017, 01:31:48 AM
About 3/24 the floe from the 'foot' bridge was opposite Petermann Fjord gong southward.  It was also there on 3/28 going northward.  It was there again yesterday (going south).
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on April 10, 2017, 07:14:44 PM
Winds in Nares Strait will be out of the north, according to Windytv (https://www.windytv.com/?2017-04-15-06,80.543,-62.139,5), all this week.  (Saturday's forecast, shown below, has the strongest winds.)  Although it has taken some 35 days to get 1/3rd of the way through, the "March 5" floe might be in Kane Basin (a 2nd third of the way) when the winds shift (predicted to be on Sunday).  I suspect all the ice in the Strait will not allow any floe to speed through as one did in early February, as it plays 'bumper cars' on its way south.
Title: Re: The Nares Strait thread
Post by: Cate on April 13, 2017, 12:39:18 PM
Big chunk out of the Lincoln Sea "boot" arch on April 12.

http://www.arctic.io/explorer/4Xa5A/2017-04-12/9-N82.26727-W60.25128 (http://www.arctic.io/explorer/4Xa5A/2017-04-12/9-N82.26727-W60.25128)
Title: Re: The Nares Strait thread
Post by: bairgon on April 13, 2017, 12:44:10 PM
I think that's out of the new ice in the "polynya" which is breaking up. If you look carefully you can see the outline of the original boot arch which is bigger.
Title: Re: The Nares Strait thread
Post by: Shared Humanity on April 13, 2017, 03:31:15 PM
I think that's out of the new ice in the "polynya" which is breaking up. If you look carefully you can see the outline of the original boot arch which is bigger.

Agreed. Sure is a lot of fresh snow in that image.
Title: Re: The Nares Strait thread
Post by: Andreas T on April 13, 2017, 07:50:05 PM
I think that's out of the new ice in the "polynya" which is breaking up. If you look carefully you can see the outline of the original boot arch which is bigger.
Using the IR images on worldview (band31) shows the thinner therefore warmer ice surface which had frozen up after the 6th March https://go.nasa.gov/2oa0lkC (https://go.nasa.gov/2oa0lkC)
temperature scale squashed to 220 / 273K

Nares strait has not exported much ice. The direction of movement has been across the top of the Lincoln sea. The effect this has had on placing thick ice into the Fram funnel and reduced multiyear ice in the Beaufort is the bigger picture here and I am curious how this will play out later in the season.
Title: Re: The Nares Strait thread
Post by: Andreas T on April 13, 2017, 08:28:10 PM
some of the breakage from the middle of january is still in place (not so easy to see because of clouds but AMSR2 helps despite low resolution) also see radar images posted by wipneus:
Breaking further, as needed.


Title: Re: The Nares Strait thread
Post by: Cate on April 15, 2017, 12:34:11 AM
That big chunk that broke off between April 11 and 12 has now made its way into the strait. Would someone reckon the distance and speed, please?  :)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on April 16, 2017, 10:36:08 PM
I think that's out of the new ice in the "polynya" which is breaking up. If you look carefully you can see the outline of the original boot arch which is bigger.

Agreed. ...
Here are the DMI (http://ocean.dmi.dk/arctic/kennedy.uk.php) Sentinel images of April 6 & 12 showing this.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on April 16, 2017, 10:42:29 PM
The 'last Arctic Ocean ice' to break off the Lincoln Sea bridge (that broke off about March 5) was in Kane Basin on April 14.

Very nearly all the ice around it, all the way upstream to the Lincoln Sea bridge, is ice that froze in Nares Strait (or the little piece of Lincoln Sea below the bridge) since early February (when 1- the bridge formed and 2- virtually all the non-fast ice in the Strait flushed out within 10 days).
Title: Re: The Nares Strait thread
Post by: gerontocrat on April 18, 2017, 07:07:39 PM
According to Jaxa, what a lot of sea ice drift in Baffin bay and Davis Strait + very thin low concentration ice in the Nares Strait
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on April 18, 2017, 08:59:31 PM
The 'last Arctic Ocean ice' to break off the Lincoln Sea bridge (that broke off about March 5) was in Kane Basin on April 14.
...
Exit, stage left.  The March 5 floe has now all-but-exited Nares Strait, depending on where you draw the line between Smith Sound and Baffin Bay. March 5 to April 18 = 44 days.  Curious that the previous identifiable floe we watched took 10 days in early February. (Screen shot from PolarView (http://bslmagb.nerc-bas.ac.uk/iwsviewer/?image=DataPolarview/111_S1jpeg2000_201704/S1B_EW_GRDM_1SDH_20170418T122422_D559_N_1.8bit.jp2).)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on April 19, 2017, 07:31:28 PM
The Lincoln Sea ("foot") bridge lost some of it's edge (or "cleaned up its act" or "got more space for the toes") sometime between 6 pm yesterday and noon today (probably GMT).  Along with some of the fast ice that grew on the bridge, some slivers (smaller than the March 5 floe) peeled off the bridge near the Ellesmere side.  You can contrast the edge with the image posted on April 16. (image from Polar View (http://bslmagb.nerc-bas.ac.uk/iwsviewer/?image=DataPolarview/111_S1jpeg2000_201704/S1B_EW_GRDM_1SDH_20170419T112602_A4F0_N_1.8bit.jp2))
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on April 19, 2017, 07:54:58 PM
The March 5 floe is definitely in Baffin Bay now, broken hearted, well, at least broken.  It was fun while it lasted.  I'm curious why it broke now. [my post #1111 - a duplicative milestone]
Title: Re: The Nares Strait thread
Post by: mati on April 19, 2017, 10:56:08 PM
lovin' the boot
lol can't belive the moniker stuck, but i'm happy :O
having a bunion, i hope the boot does not fall to one
Title: Re: The Nares Strait thread
Post by: oren on April 19, 2017, 11:30:57 PM
Here's a quick animation of Apr 18 and 19. The ice is more broken, the cracks are getting closer to the "arch" while the newer ice inside the arch falls away.
I would not be surprised to see the arch crumbling within a few days under the stresses.  It's not a given but quite possible. And if it does go, I don't expect a new arch to form and stabilize as temps are going up already and the strait itself has been flushed away.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on April 24, 2017, 05:46:56 AM
The pieces of "foot" bridge ice that broke off the "toe section" on April 19 are past or opposite Petermann Fjord (as of yesterday's DMI (http://ocean.dmi.dk/arctic/kennedy.uk.php) Sentinel image):
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on April 25, 2017, 05:57:36 PM
The April 19 "toes" floes were at or just past Hans Island yesterday, per PolarView (http://bslmagb.nerc-bas.ac.uk/iwsviewer/?image=DataPolarview/111_S1jpeg2000_201704/S1A_IW_GRDH_1SDH_20170424T122449_ABEE_N_1.8bit.jp2) (image below).
They are certainly not taking a leisurely trip through Nares Strait as the March 5 floes did!

You can see the fast ice held by Franklin Island in this screen print.  (Some of it was from the Arctic Ocean - it solidified before the early February cleansing of all the ice in the open parts of Nares Strait. [Of course, while all the ice was getting flushed, new ice was forming 'upstream' within the Strait & Lincoln Sea.])  More recent fast ice is held in place by Hans Island, the Franklin fast ice, and Greenland.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on April 27, 2017, 02:47:55 AM
The April 19 "toes" floes are in the central part of Kane Basin, as of mid-day today, per PolarView (http://bslmagb.nerc-bas.ac.uk/iwsviewer/?image=DataPolarview/111_S1jpeg2000_201704/S1B_EW_GRDM_1SDH_20170426T125651_3D25_N_1.8bit.jp2).  The biggest floe (that I'm watching) may make it to Baffin Bay in under 10 days. (Images: larger scale 'closeup' first, smaller scale screen shot for better orientation second [shows the top of Kane Basin])
Title: Re: The Nares Strait thread
Post by: Cate on April 27, 2017, 01:03:05 PM
Tor, thank you for posting these images with your commentary. I want to learn more about what I am looking at here, and find your posts instructive and helpful.
Title: Re: The Nares Strait thread
Post by: gerontocrat on April 27, 2017, 01:24:37 PM
Jaxa sea ice drift graph shows strong to very strong drift down Baffin Bay and Davis Strait. Yet cci-reanalyzer says very little wind. So strong southerly currents?
Title: Re: The Nares Strait thread
Post by: bairgon on April 27, 2017, 11:59:13 PM
The boot has just got a little bigger. This appears to be thicker ice that is coming away, rather than the clearing of the fresh ice that we had a week or so ago.

See https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-04-27&z=3&v=-636508.3781804984,-1066229.2989938147,346531.6218195016,-561909.2989938147 (https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-04-27&z=3&v=-636508.3781804984,-1066229.2989938147,346531.6218195016,-561909.2989938147)

Title: Re: The Nares Strait thread
Post by: johnm33 on April 28, 2017, 12:21:04 AM
Zoom in and look at LIncoln it seems a collapse may be imminent. https://www7320.nrlssc.navy.mil/GLBhycomcice1-12/navo/arcticictn_nowcast_anim30d.gif
Title: Re: The Nares Strait thread
Post by: mati on April 28, 2017, 04:45:06 AM
toes are showing :)
Title: Re: The Nares Strait thread
Post by: Wipneus on April 28, 2017, 12:32:49 PM
Indeed, here seen by the Sentinel 1 radar.
Title: Re: The Nares Strait thread
Post by: Shared Humanity on April 28, 2017, 02:42:23 PM
That animation shows open water still freezing.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on April 28, 2017, 07:17:16 PM
The April 19 big "toe" floe is in southernmost Kane Basin (almost in Smith Sound) as of mid-day today (screen shot from PolarView (http://bslmagb.nerc-bas.ac.uk/iwsviewer/?image=DataPolarview/111_S1jpeg2000_201704/S1A_EW_GRDM_1SDH_20170428T115223_781D_N_1.8bit.jp2)), so it won't beat the 10 day pace the early February floe had. (Will it tie?)  Now that this floe is nearing the Nares exit, I'll get to watch the April 27 "toe".
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on April 30, 2017, 10:28:52 PM
The April 19 "toe" floe was in Smith Sound yesterday (frist screen print from DMI-Kane-Sentinel (http://ocean.dmi.dk/arctic/kane.uk.php) is dated April 29), so probably 11 days to transit the length of Nares Strait. Edit: the 3rd image below, from PolarView (http://bslmagb.nerc-bas.ac.uk/iwsviewer/?image=DataPolarview/111_S1jpeg2000_201704/S1B_EW_GRDM_1SDH_20170430T122422_F14D_N_1.8bit.jp2), shows this floe in Baffin Bay on the 30th, so, yes: 11 days.

Meanwhile, the April 27 "toe" floe is half way to Petermann Fjord. (second screen print - DMI-Kennedy-Sentinel is dated April 30)

[For those who wonder why I'm calling these "toe" floes, the Lincoln Sea ice bridge (or arch) left the shape of a foot (therefore a "foot bridge") or boot, with the ankle being the Kennedy Channel (northern part of Nares Strait).  When these floes broke off of the ice bridge, they came from the area where toes would be if it had been a real foot or boot, therefore "toes".  That these two floes are elongated just adds to the illusion. (That their length came from the width of the boot's toe section could be cause to call them each a set of "toes", but the anthropomorphizing can go too far, even for me).]
Title: Re: The Nares Strait thread
Post by: bairgon on May 03, 2017, 09:32:03 PM
I've been watching this ice separating in the Kane basin recently. For the latest picture see https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-05-03&z=3&v=-749189.3189376687,-1208306.8597371846,-257669.3189376687,-956146.8597371846&ab=on&as=2017-04-18&ae=2017-05-03&av=2&al=true (https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-05-03&z=3&v=-749189.3189376687,-1208306.8597371846,-257669.3189376687,-956146.8597371846&ab=on&as=2017-04-18&ae=2017-05-03&av=2&al=true)

I think it's about 30km by 80km, which is 2400 km^2. Rather a lot really!

Winds are forecast to be from the southwest so it may travel up the strait a bit before being flushed out.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 04, 2017, 09:28:33 PM
The April 27 "toe" floe flew past Hans and Franklin Islands yesterday and is probably in Kane Basin today.  It might, however, get "stuck" in Kane Basin for a while.  Screen shot with a red dot on the floe is from yesterdays DMI (http://ocean.dmi.dk/arctic/kennedy.uk.php)-Sentinel.

Separately, I'm intrigued by the large section of fast ice in the southwestern part of Kane Basin that broke free so early in the year. (Thanks, bairgon!)  Windytv (https://www.windy.com/?2017-05-06-00,78.888,-71.505,7) shows confused winds until Sunday.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 05, 2017, 02:54:06 PM
The April 27 "toe" floe flew past Hans and Franklin Islands yesterday and is probably in Kane Basin today.  ...
Well, it got to the edge of Kane Basin, anyway.  Screen shot (red dot added) from Polar View (http://www.polarview.aq/arctic) dated 2017-05-04 at 8:50 PM (http://bslmagb.nerc-bas.ac.uk/iwsviewer/?image=DataPolarview/111_S1jpeg2000_201705/S1A_IW_GRDH_1SSH_20170504T205008_7467_N_1.8bit.jp2)
Title: Re: The Nares Strait thread
Post by: Cate on May 05, 2017, 03:47:18 PM
Tor, great chronology of the "toe floe"--thanks.

That big ship-shaped piece on the Greenland side of Kane Basin has floated her substantial stern well out into the road today.

:)
Title: Re: The Nares Strait thread
Post by: johnm33 on May 05, 2017, 09:35:52 PM
Tor"I'm intrigued" My guess high pressure+low tides
Title: Re: The Nares Strait thread
Post by: DavidR on May 06, 2017, 12:51:33 AM
I've been watching this ice separating in the Kane basin recently.
I think it's about 30km by 80km, which is 2400 km^2. Rather a lot really!

Winds are forecast to be from the southwest so it may travel up the strait a bit before being flushed out.

This seems large enough to block the channel if it moves down in the right way.  So while its possible it could flush out or break up, there is also a chance it could form the basis of a late arch blocking the channel.  Having come from a shelf it  could be more solid than the ice that  is forming in the channel and flowing  down.
Title: Re: The Nares Strait thread
Post by: RikW on May 08, 2017, 01:27:16 PM
I was just looking at Worldview and I see huge cracks getting 'near' the arch from Beaufort Sea - it just flew by the Queen Elizatbeth Islands and a new one forming above Ellesmere...
Just in 3 days from almost nothing visible to a I think 5 km wide crack

And also a lot of cracks forming above greenland getting nearer to the arch.

Just as if the nares strait arch will be the last man standing
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 08, 2017, 06:52:42 PM
The April 27 "toe" floe past through Smith Sound yesterday - 10 days to go the distance (just like the early February floe). (image from DMI (http://ocean.dmi.dk/arctic/kane.uk.php))  So much for (much of) a slowdown in Kane Basin!
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 08, 2017, 07:39:24 PM
I was just looking at Worldview and I see huge cracks getting 'near' the arch from Beaufort Sea - it just flew by the Queen Elizatbeth Islands and a new one forming above Ellesmere...
Just in 3 days from almost nothing visible to a I think 5 km wide crack

And also a lot of cracks forming above greenland getting nearer to the arch.

Just as if the nares strait arch will be the last man standing
Windytv (https://www.windy.com/?2017-05-10-06,82.913,-54.250,5,m:fW4aevu) forecast shows winds out of the south for the Lincoln Sea on Wednesday.  It is still early in the season, but with other ice shifting (and cracks forming), maybe this will break the Nares Strait "foot" bridge.
Title: Re: The Nares Strait thread
Post by: Wipneus on May 09, 2017, 07:39:07 PM
The floe in the Kane Basin breaks away.

Click for the animation.
Title: Re: The Nares Strait thread
Post by: dosibl on May 09, 2017, 11:05:54 PM
Looks like some cracks have made it to the heel, can't be good for the arch.

https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-05-09&z=3&v=-471412.5827169074,-870724.4521707678,183947.4172830926,-529220.4521707678 (https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-05-09&z=3&v=-471412.5827169074,-870724.4521707678,183947.4172830926,-529220.4521707678)
Title: Re: The Nares Strait thread
Post by: oren on May 09, 2017, 11:33:07 PM
Nice catch. At zoom-out they are invisible.
Definitely can't be good for the arch.
Edit: two tiny pieces already broke off the heel.
Title: Re: The Nares Strait thread
Post by: Darvince on May 10, 2017, 01:36:27 AM
This is likely the end of the 2017 Nares Strait arch. Cracks propogated all the way down to the arch and a large floe from atop the arch was released. Another crack may be continuous all the way to Ellesmere Island, but the resolution of Terra Worldview is too poor to tell. There is a third less well-defined crack that definitely extends over to Ellesmere Island from the top of the arch.

I would not be surprised if large quantities of MYI started flowing down through the Nares Strait soon, although I also would not be surprised if it somehow held together as these arches definitely manage to take a beating before collapsing in the summer.

GIF-making over this region as the next week comes in will be instructive.
Title: Re: The Nares Strait thread
Post by: mati on May 10, 2017, 01:51:02 AM
the toe has hangnails :O
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 10, 2017, 05:04:14 AM
windytv "current" forecast winds aren't helping the bridge/arch any!
Title: Re: The Nares Strait thread
Post by: johnm33 on May 10, 2017, 10:51:34 AM
Cracks coming across from Fram too
(https://gibs.earthdata.nasa.gov/image-download?TIME=2017129&extent=-401020.7178722848,-895207.821869317,228739.28212771518,-376039.821869317&epsg=3413&layers=MODIS_Terra_CorrectedReflectance_TrueColor,Coastlines,Reference_Features&opacities=1,1,1&worldfile=false&format=image/jpeg&width=1230&height=1014)
from https://go.nasa.gov/2pv9yE8
Title: Re: The Nares Strait thread
Post by: romett1 on May 10, 2017, 01:46:32 PM
Some rapid changes overnight. Seems like the first block is now trying to enter the Nares Strait. Bit cloudy on May 10.
Title: Re: The Nares Strait thread
Post by: Shared Humanity on May 10, 2017, 03:25:45 PM
That crack that is running along the coast of Greenland is evidence of the ice directly north of Nares sheering away from the coastal ice. Would not be at all surprised if this ice floe is the first of many to peel off and head south through the strait.
Title: Re: The Nares Strait thread
Post by: dosibl on May 10, 2017, 08:42:20 PM
Worldview images from today show the foot is history.

https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-05-10&z=3&v=-404348.04562090896,-894889.1561871079,15235.95437909104,-685481.1561871079 (https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-05-10&z=3&v=-404348.04562090896,-894889.1561871079,15235.95437909104,-685481.1561871079)
Title: Re: The Nares Strait thread
Post by: TerryM on May 10, 2017, 10:14:27 PM
Worldview images from today show the foot is history.

https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-05-10&z=3&v=-404348.04562090896,-894889.1561871079,15235.95437909104,-685481.1561871079 (https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-05-10&z=3&v=-404348.04562090896,-894889.1561871079,15235.95437909104,-685481.1561871079)


That's a good bit of MYI leaving the arena.
Terry
Title: Re: The Nares Strait thread
Post by: Thomas Barlow on May 10, 2017, 11:43:46 PM
Worldview images from today show the foot is history.

https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-05-10&z=3&v=-404348.04562090896,-894889.1561871079,15235.95437909104,-685481.1561871079 (https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-05-10&z=3&v=-404348.04562090896,-894889.1561871079,15235.95437909104,-685481.1561871079)

Ice didn't start really moving through there until July last year.
https://media.giphy.com/media/xUA7b1n5DHGHHmDHwc/giphy.gif
Title: Re: The Nares Strait thread
Post by: oren on May 11, 2017, 12:10:54 AM
Amazing how it all went in one blow. I did expect it to break a few weeks ago when the cracks first showed up in the area, but when the initial danger passed I was hoping the arch could survive.
Considering the Lincoln Sea is one of the last resorts of thick old static MYI, this is another piece of bad news for the melting season. There is no arch in Kane Basin and the strait has already been flushed recently, so resistance to southbound export will be minimal besides the normal "traffic jams". Extent might not suffer in the beginning, should even go up in the vicinity, but volume-wise and fast forwarding to the next few months, it's one more nail in the coffin.
Title: Re: The Nares Strait thread
Post by: be cause on May 11, 2017, 02:14:03 AM
we could be chatting about that snap for a while . the last thing the Arctic needed was an outlet for more of the thicker ice . What happened suggests that being in the coldest safest place for several months has done nothing to give our best ice any staying power .. bc

  p.s. .. i suppose we could say this foot now has a fallen arch .. boom boom :)
Title: Re: The Nares Strait thread
Post by: johnm33 on May 11, 2017, 10:53:17 AM
The big berg in the south is not moving very much, considering the tides, if it stays put Kane may fill with the sea ice from Lincoln.
Title: Re: The Nares Strait thread
Post by: DavidR on May 11, 2017, 03:06:38 PM
The latest break to the Nares boot may release some thicker multi year ice that is more resistant to  break up and thus more likely to jam up as it  flows through the strait.  Seems to  be the only  way  an arch  could form in Kane basin now.

The next  week  or two will be interesting to  see whether it all just  flows through.

Winds in Nares are turning southwest  from tomorrow so the ice should resume flowing steadily down the strait for several days.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 11, 2017, 04:10:15 PM
DMI (http://ocean.dmi.dk/arctic/lincoln.uk.php) Sentinel before (May 8 ) and after (May 10) images show the 'left' 2/3rds of Lincoln Sea ice rotating counterclockwise and the 'right' 1/3rd (but including the 'heel' and 'foot' part of the boot, but not the tip of the 'toes' [yet]) sliding very slightly (except for areas closest to the 'boot') SW-ward (straight for Nares Strait).  Most of the ice from the 'toe' section that broke off is young fast ice.

Temporarily, the boot's arch looks better than ever!  Seeing is deceiving!
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 11, 2017, 06:11:30 PM
I wonder how quickly the large floe in Kane Basin (that recently was fast ice in Kane Basin, most of which had been in place since early December 2016) will pass through Smith Sound.  I doubt it will go through mostly intact, but we'll see.  The current 'forecast', according to windytv (https://www.windy.com/?2017-05-12-18,79.608,-66.292,5,m:fO4ad6C) has fairly calm winds, but north winds are forecast (see image below) to help move the floe southward by tomorrow. (1st image below is from WorldView (https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-05-10&z=3&v=-906973.6993692394,-1293432.8841532517,-188637.6993692394,-896120.8841532518).)

I'll hazard a guess the tail end of the floe will pass into Baffin Bay on Tuesday, May 16.

By the way, folks who post long links should link a word or phrase instead of the long ling.  To do so, (I added some 'invisible' spaces in this example so the computer won't read the example as code.)
Title: Re: The Nares Strait thread
Post by: romett1 on May 11, 2017, 08:33:55 PM
Nares Strait May 9 - May 11, Worldview.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 11, 2017, 09:32:10 PM
I don't often look at NOAA imagery on the DMI site (http://ocean.dmi.dk/arctic/lincoln.uk.php), but here is today's Lincoln Sea.  Looks like  a shoe now (no longer a boot). (Is this where we remind each other "Don't eat yellow snow"?)
Title: Re: The Nares Strait thread
Post by: oren on May 11, 2017, 09:47:22 PM
Tor thanks for the URL help (and the great info you always post here...)
Title: Re: The Nares Strait thread
Post by: oren on May 12, 2017, 01:55:08 PM
Did some quick research about approx. breakup times, southern "arch" in Kane Basin unless noted otherwise:
2007 - No arches formed.
2008 - June 10th(?)
2009 - No southern arch. Northern arch broke around June 30th.
2010 - July 10th
2011 - July 5th.
2012 - June 30th.
2013 - July 10th.
2014 - June 20th.
2015 - July 5th.
2016 - June 30th
2017 - No southern arch. Northern arch broke around May 10th.

Yes, it's early.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 12, 2017, 07:05:06 PM
Thanks, oren!  I wonder if Baffin Bay had more ice than in other years in 2009 due to more Nares-Strait-born ice getting created and exported. (Similar question for 2007.)

There is no Lincoln Sea shoe (I didn't expect it to last long), just jagged (recently broken) floes just starting to enter Nares Strait.  DMI (http://ocean.dmi.dk/arctic/kennedy.uk.php) image (screen shot) is dated today.  Windytv (https://www.windy.com/?2017-05-14-09,81.025,-55.415,4,m:fU4aepy) wind forecast for tonight shown.
Title: Re: The Nares Strait thread
Post by: Neven on May 12, 2017, 10:25:41 PM
Did some quick research about approx. breakup times, southern "arch" in Kane Basin unless noted otherwise:
2007 - No arches formed.
2008 - June 10th(?)
2009 - No southern arch. Northern arch broke around June 30th.
2010 - July 10th
2011 - July 5th.
2012 - June 30th.
2013 - July 10th.
2014 - June 20th.
2015 - July 5th.
2016 - June 30th
2017 - No southern arch. Northern arch broke around May 10th.

Yes, it's early.

Thanks, oren. I always wanted to do this (as well as for the NWP and NSR), but never got around to it. I know some of these break-up times can be found on the ASIB, and some on Patrick Lockerby's Science 2.0 Blog. Did you use other sources as well?
Title: Re: The Nares Strait thread
Post by: romett1 on May 12, 2017, 10:31:01 PM
Nares Strait May 10 - May 12, Worldview.
Title: Re: The Nares Strait thread
Post by: oren on May 13, 2017, 12:29:31 AM
Thanks, oren. I always wanted to do this (as well as for the NWP and NSR), but never got around to it. I know some of these break-up times can be found on the ASIB, and some on Patrick Lockerby's Science 2.0 Blog. Did you use other sources as well?
Being ignorant on most sources, I actually used imagery on Worldview from 2012 onward (accurate), NSIDC concentration on Worldview for the earlier years (crude - is there visual Worldview before 2012?), and this paper which gives some information:
The effects of ice arch formation on currents in Nares Strait during the springs of 2008 and 2009 (http://people.oregonstate.edu/~einolfa/Einolf_Honors.pdf)

Regarding effects of arches, according to the above-mentioned paper in 2009 (year with only northern arch) the southbound current in Nares was much stronger than in 2008 . And Kwok et al (2010) report that in 2007 (year with no arch) the total annual ice export was more than twice that of other years.
As for Baffin extent (NSIDC), I generated this quick and dirty chart of years and day of year which I think implies extent wasn't visibly impacted by the increased export in 2007 and 2009. Note there is no down trend in extent either. All to say that Baffin melts in its own time every year regardless of what is exported into it and regardless of the overall melting season. So any ice exported through Nares weakens the CAB without having any positive impact elsewhere.
Title: Re: The Nares Strait thread
Post by: johnm33 on May 13, 2017, 12:39:07 AM
So is that big chunk grounded?
(https://puu.sh/vO8A3/16706663f6.jpg)
from https://lance3.modaps.eosdis.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2017132185500-2017132190000.1km.jpg
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 13, 2017, 12:55:43 AM
I doubt it. Nope.  I believe it is all first year ice, and not over 2 meters or so thick.  I think it is just big and sluggish.  I expect winds and current (what little there is in Kane Basin) will move it southward these next few days.  (Winds were not helpful a couple days ago.)  Here is a screen shot from a bathimetry map of Kane Basin:  Oceanographic Cruse Summary Kane Basin September 1969 (I cannot copy the link for some reason, but an internet search should be able to duplicate the find!) 
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 13, 2017, 04:20:21 PM
Kane Basin's "Big Chunk" seems to be caught in the Kane Basin gyre.  Without steady winds from the north, there is often a noticeable counterclockwise spin (e.g., reference (http://arctic.journalhosting.ucalgary.ca/arctic/index.php/arctic/article/view/3432)).  Given how it is moving (see Wipneus's movie on Home brew thread (http://forum.arctic-sea-ice.net/index.php/topic,382.msg113365.html#msg113365)), my guess when it would head south may have been premature.

Here is a Lincoln Sea 'close up' of what johnm33 posted (yesterday's WorldView (https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-05-12&z=3&v=-358343.6214028493,-870375.7264240072,-48327.62140284933,-690151.7264240072)) (Image from yesterday)
Title: Re: The Nares Strait thread
Post by: romett1 on May 13, 2017, 07:33:05 PM
Latest images of Nares Strait, May 11 - May 13 (Worldview).
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 13, 2017, 09:51:36 PM
When the Lincoln Sea ice bridge first began to break (1st day or so), I saw new cracks (specifically, two on the right) radiating quite a distance into the Arctic (see my May 11 post above, reproduced just below).  I don't see those cracks anymore, as if they were healed (certainly squeezed back together).  I suspect the ice in the Lincoln Sea has returned to a state of short-term temporarily-stable arches that will repeatedly shed ice.  I'm picturing an hour glass with coarse angular sand (not well rounded grains) that repeatedly get stuck in the neck, but a little shake of the hour glass will get them flowing again.  The convergent forces on the ice, I'm sure, are just asking for bridges to form!
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fforum.arctic-sea-ice.net%2Findex.php%3Faction%3Ddlattach%3Btopic%3D176.0%3Battach%3D45125%3Bimage&hash=261639f6f72b348d353b22f6168f0d36)
This 2nd image is from today's DMI Sentinel (http://ocean.dmi.dk/arctic/lincoln.uk.php)
Title: Re: The Nares Strait thread
Post by: Neven on May 13, 2017, 10:34:13 PM
Thanks, oren. I always wanted to do this (as well as for the NWP and NSR), but never got around to it. I know some of these break-up times can be found on the ASIB, and some on Patrick Lockerby's Science 2.0 Blog. Did you use other sources as well?
Being ignorant on most sources, I actually used imagery on Worldview from 2012 onward (accurate), NSIDC concentration on Worldview for the earlier years (crude - is there visual Worldview before 2012?), and this paper which gives some information:
The effects of ice arch formation on currents in Nares Strait during the springs of 2008 and 2009 (http://people.oregonstate.edu/~einolfa/Einolf_Honors.pdf)

Regarding effects of arches, according to the above-mentioned paper in 2009 (year with only northern arch) the southbound current in Nares was much stronger than in 2008 . And Kwok et al (2010) report that in 2007 (year with no arch) the total annual ice export was more than twice that of other years.

When I have time, I'll try and check those dates on my blog and on Patrick's. I know I have animations for a couple of those years. Not that I think the dates aren't correct. They most probably are.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 15, 2017, 06:33:38 PM
cross post from "The 2017 melting season" thread:
(The following posts there discuss Nares Straight as well.)
Speaking of the relative soda straw that is the Nares. The first image below is a current still of the entire straight - click if you want to zoom in. The second is an animation from 4/28 to 5/14 of Kane Basin (at bottom of the straight). Check out the movement of the big slab - notice i didn't say big block  ::).  Wondering how that slab will fare given the favorable-for-export winds that are forecasted. Also at the end of the animation, notice the comparison between 4/28 and 5/14 - lots of slush ice seems to have melted and/or made its way out.

Edit: I had to compress the gif more so that it would play i guess 6mbs is too big for this site? The gif compressor app removed the loop so it won't start over from the beginning.  If you want to see it again you'll have to right click on it and open it in a new browser tab to restart the animation.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fforum.arctic-sea-ice.net%2Findex.php%3Faction%3Ddlattach%3Btopic%3D1834.0%3Battach%3D45254%3Bimage&hash=eab6bf7c6f272594c640beb6f854b76a)
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fforum.arctic-sea-ice.net%2Findex.php%3Faction%3Ddlattach%3Btopic%3D1834.0%3Battach%3D45258%3Bimage&hash=3097f60f9d722b352cd8a79c8ab7d274)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 15, 2017, 06:54:40 PM
Winds in Kane Basin, according to windytv (https://www.windy.com/?79.711,-62.512,5,m:fPfad6C), are often more gentle than they are further south in Smith Sound or further north in the Kennedy Channel.  Today's 'now' forecast is an example of this.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 15, 2017, 09:39:35 PM
When the Lincoln Sea ice bridge first began to break (1st day or so), I saw new cracks (specifically, two on the right) radiating quite a distance into the Arctic ...  I suspect the ice in the Lincoln Sea has returned to a state of short-term temporarily-stable arches that will repeatedly shed ice.  ...  The convergent forces on the ice, I'm sure, are just asking for bridges to form!
...
Today's World View (https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-05-15&z=3&v=-587890.9377238179,-931401.98768477,173453.0622761821,-548425.98768477) of the Lincoln Sea sure suggests these "short-term temporarily stable arches" are very short-term and temporary!
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 16, 2017, 06:26:08 PM
Another interesting post to cross post:
Any idea how Nares compares with Fram on volume basis?
Looks like Nares export (on any measure) will be unusually large this year, owing to lack of arch formation.

Looking at the export over the last couple of days at start of the Robeson Channel (see gif) I estimate about 500 km^2 exported per day (each of the big rectangular blocks are around 20k x 10k). If the ice is 2m thick that is about 1 km^3 per day.

Assuming that we have an additional 2 month's flow through Nares compared to previous years, that is an additional 60 km^3 lost which is, very roughly, about 2-3% of the total ice volume in September.

So it's not very significant; but could make an impact in the thickest area.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fforum.arctic-sea-ice.net%2Findex.php%3Faction%3Ddlattach%3Btopic%3D1834.0%3Battach%3D45307%3Bimage&hash=2a612facbf47576950d9ee601a2c54ae)
Title: Re: The Nares Strait thread
Post by: dosibl on May 16, 2017, 07:34:26 PM
Worldview images from today show another large jump in cracking area, almost the entire region looks compromised.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 16, 2017, 07:39:45 PM
Another cross-post:
....
bairgon, thanks for the analysis. I think these floes are suposedly closer to 4m thick than to 2m thick, so maybe it's double the volume exported.

measurements taken by scientists on the ice in that area show a mean thickness of 3m
http://blogs.esa.int/campaignearth/2017/05/01/cryovex-first-results-show-sea-ice-continues-to-thin/ (http://blogs.esa.int/campaignearth/2017/05/01/cryovex-first-results-show-sea-ice-continues-to-thin/)
Screen shot from this paper showing the four (western) Lincoln Sea ice bridge ice thickness measurements [and snow depths] on (apparently) April 12, 2017:
Quote
At 12 Twin Otter landing sites between 83N and 87.1N, we gathered 36.7 km of electromagnetic (EM) ice- and snow-thickness data and acquired some 13 000 snow-thickness measurements. EM soundings were calibrated with drill-hole measurements. Data were edited to remove any bias due to thinner snow and ice conditions in the immediate vicinity of our landing sites, which were mostly on refrozen leads. Our results represent conditions on thick, old first- and multiyear ice floes typical for the wider regions around the landing sites.
Title: Re: The Nares Strait thread
Post by: romett1 on May 16, 2017, 08:23:08 PM
Worldview images from today show another large jump in cracking area, almost the entire region looks compromised.

Yes, Nares has decided to attract ice from 84°N - 85°N. Images: Worldview, May 14 - May 16.
Title: Re: The Nares Strait thread
Post by: oren on May 16, 2017, 08:43:13 PM
The big slab in Kane basin has completed a 180 degree turn, and is now poised for head-first birth into Baffin bay.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 16, 2017, 08:59:22 PM
I was thinking it was a ship, docked for the winter facing up stream, getting launched and turned around, and now heading slowly (~5 km/day?) toward Smith Sound and beyond.

If it's a baby that started growing this past winter, I wonder if it knows that there's a cruel world out there!
Title: Re: The Nares Strait thread
Post by: romett1 on May 17, 2017, 08:17:38 PM
So far seems like it's going smoothly down towards Nares Strait and some new cracks further north. May 15 - May 17, Worldview.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 18, 2017, 04:27:43 PM
"Big Chunk" (the largest piece of fast ice that broke off within Kane Basin on April 22 [other pieces broke off earlier]) is definitely heading into Smith Sound, finally (and slowly - 10 km/day).  Pieces of the "foot bridge" (or was it "arch of the boot"?) in Lincoln Sea (that broke on May 10) are catching up quickly - 100 km/day (purple arrows)! Worldview (https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-05-17&z=3&v=-804863.9999999998,-1190400.0000000002,-43519.99999999977,-807424.0000000002) screen shot below from May 17.  Floe speed determined by comparing May 16 & 17 images.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 19, 2017, 04:42:29 PM
"Big Chunk" moved about 4 km between May 17 and 18, while the "foot bridge" pieces moved about 85 km.  What will today bring? Winds, per windytv, are mildly contrary today (contrary for southward travel).  Currents favor export, winds favor stillness.
Title: Re: The Nares Strait thread
Post by: Phil. on May 19, 2017, 05:12:14 PM
"Big Chunk" moved about 4 km between May 17 and 18, while the "foot bridge" pieces moved about 85 km.  What will today bring? Winds, per windytv, are mildly contrary today (contrary for southward travel).  Currents favor export, winds favor stillness.

As of 11:15 UCT today it looks like three pieces have blocked the entrance (temporarily?), it'll be interesting to see what happens there.
Title: Re: The Nares Strait thread
Post by: Phil. on May 20, 2017, 10:53:28 PM
As of today that temporary dam has broken and many more chunks of ice are entering the strait.

https://lance3.modaps.eosdis.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2017140180500-2017140181000.2km.jpg
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 20, 2017, 11:53:51 PM
In Kane Basin (and Smith Sound) Big Chunk (BC) looks like it intends to shut off the export of the pesky Foot Bridge floes like the ones that just zoomed right past BC yesterday and today, but I don't think it will succeed.  It is curious to watch the little floes zip along and the big oaf lumbers erratically along.
Title: Re: The Nares Strait thread
Post by: Andreas T on May 21, 2017, 12:35:16 AM
without offering any evidence I seem to remember that the western side of the straight is usually flowing faster than the eastern side, this made big chunk rotate so swiftly I  think. The odd thing is that it isn't drawn towards the west or does another rotation. Maybe the wind has an effect?
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 21, 2017, 03:09:24 AM
According to windytv (https://www.windy.com/?79.620,-62.095,5), the current winds are mild and from the north, helping floes go south. 

A paper discussed a couple or several years ago on this thread detailed that most of the Nares Strait has a current that flows south on the western side and a small current flows to the north on the eastern side. (I tried, but failed, to find the reference. Anybody have it?  It was alluded to a few days ago.)
Title: Re: The Nares Strait thread
Post by: TerryM on May 21, 2017, 03:47:49 AM
Tor
The most up to date & detailed information on Nares currents is likely to be found at Dr Muenchow's site


https://icyseas.org/


Andreas posts here and at Neven's Blog from time to time. He's very open to questions about his work & very free with his vast knowledge.


https://icyseas.org/2014/09/21/a-short-summary-of-nares-strait-physics/


Will take you to a summary of Nares Strait from 2014 - but much more is available roaming his pages,


Have Fun!
Terry
Title: Re: The Nares Strait thread
Post by: bairgon on May 21, 2017, 09:49:03 AM
I found this in https://icyseas.org/2015/07/13/oceanography-of-nares-strait-ice-flushing/ (https://icyseas.org/2015/07/13/oceanography-of-nares-strait-ice-flushing/):

"Now there is more to the “hill” story that is modified near the surface by the earth’s rotation in a fluid that has different densities at different depths. In a nutshell, the surface flow is 2-3 times as strong as the depth averaged flow. Furthermore, the surface flow on the Canadian side of Nares Strait is often twice as strong as that closer to Greenland, but all these spatial variations in flow actually help to smash large pieces of ice by moving and rotating them different sides of the same large piece of ice differently."
Title: Re: The Nares Strait thread
Post by: Phil. on May 21, 2017, 05:45:58 PM
without offering any evidence I seem to remember that the western side of the straight is usually flowing faster than the eastern side, this made big chunk rotate so swiftly I  think. The odd thing is that it isn't drawn towards the west or does another rotation. Maybe the wind has an effect?

The block appears to have just developed a crack about two thirds of the way down, I expect we'll see more developments now.  The crack appears to have originated at the point of contact with the coast?
Title: Re: The Nares Strait thread
Post by: FishOutofWater on May 21, 2017, 06:01:02 PM
The crack in the large ice flow is widest where it collided with the small fast moving diamond shaped block. That may be where the crack initiated.
Title: Re: The Nares Strait thread
Post by: Shared Humanity on May 21, 2017, 07:00:18 PM
The crack in the large ice flow is widest where it collided with the small fast moving diamond shaped block. That may be where the crack initiated.

I think the crack was caused by it slamming into land on the Greenland side. (Wouldn't that be cool to watch?) The front flow is now pivoting on that point.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 21, 2017, 09:17:41 PM
Looks like a hammer [stone] (small floe) and anvil (Greenland) approach to floe size reduction (of Big Chunk), or a wedge and Big Chunk in a tightening vice.
Title: Re: The Nares Strait thread
Post by: Reallybigbunny on May 21, 2017, 09:38:56 PM
 8) The crack is developing swiftly!

Title: Re: The Nares Strait thread
Post by: oren on May 22, 2017, 12:49:25 AM
Regardless of the (interesting) details, this thing is not going to plug Kane Basin. The way is open and will stay open until the end of the year.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 22, 2017, 03:00:11 AM
I fully agree with you, oren, but it is fun watching ice appear to 'attempt' to close things down (with inadequate 'tools'), at both ends, even when they last only half a day.
Title: Re: The Nares Strait thread
Post by: oren on May 22, 2017, 07:27:28 AM
Agreed. It is fun watching, and even educational when such a large piece of (first-year) fast ice crumbles at first contact without offering any resistance.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 22, 2017, 04:31:04 PM
Yesterday's DMI Sentinel (http://ocean.dmi.dk/arctic/kennedy.uk.php) imagery shows a large "diamond" floe entering Robeson Channel (the northern section of Nares Strait).  It's narrowest width is about 17 km.  I look forward to its interacting with Hans Island, as there is only about 15 km of passageway available to passing floes.  (Or will "Diamond" be 'faceted' before then due to its many flaws?) [The fast ice area is greater than that represented by the yellow line.  Both screen prints are from the same DMI image.] [Huge edit/woops, written on May 23: Fast ice on Hans Is. broke about May 9.  This image shows fast ice on Franklin Is. and passing floes (mostly) between Hans and Greenland.  See my May 23 post for some details.  This doesn't much affect the concerns raised in this original post, however.]
Title: Re: The Nares Strait thread
Post by: dosibl on May 22, 2017, 07:02:43 PM
From today's worldview images the diamond is already gone.

https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor,MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-05-22&z=3&v=-701895.3866677409,-1026908.8185694336,137272.61333225912,-608092.8185694336 (https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor,MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-05-22&z=3&v=-701895.3866677409,-1026908.8185694336,137272.61333225912,-608092.8185694336)
Title: Re: The Nares Strait thread
Post by: romett1 on May 22, 2017, 09:08:03 PM
From today's worldview images the diamond is already gone.


That was quick. I thought maybe this diamond will survive some weeks.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 22, 2017, 09:34:28 PM
Diamonds, although very hard (10 of 10 on Mohs scale (https://en.wikipedia.org/wiki/Mohs_scale_of_mineral_hardness)), are quite brittle: bouncing off the Greenland coast did "the Diamond" floe in. (Boy was it faceted!)  'Gotta name these floes fast or you'll miss your chance.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 22, 2017, 09:51:06 PM
Cross post (thanks, Tigertown):
Where did it go?
Charts show this that's now ice entering Nares to be old thick ice, but the way it crumbles makes for doubt. 5-21 vs. 5-22
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fforum.arctic-sea-ice.net%2Findex.php%3Faction%3Ddlattach%3Btopic%3D1834.0%3Battach%3D45581%3Bimage&hash=29d4285bae00886a77e174496fee5d43)
Title: Re: The Nares Strait thread
Post by: be cause on May 22, 2017, 11:26:59 PM
it may be old thick ice but as Sentinel images show the diamond was a molsaic of shattered fragments randomly conglomerated and held together by ... not very much .
there is little old ice with any more integrity anywhere in the Arctic .
Title: Re: The Nares Strait thread
Post by: Shared Humanity on May 22, 2017, 11:34:25 PM

there is little old ice with any more integrity anywhere in the Arctic .

I agree.
Title: Re: The Nares Strait thread
Post by: Apocalypse4Real on May 23, 2017, 12:40:03 AM
There is not much multi-year ice up there, and what there is is broken up with thinner lead ice in between, often less than a meter thick. Julienne Stroeve ran an ice thickness campaign to ground substantiate the Cryosat measurements along with Ice Bridge.

Here are three links:

http://blogs.esa.int/campaignearth/2017/05/01/cryovex-first-results-show-sea-ice-continues-to-thin/ (http://blogs.esa.int/campaignearth/2017/05/01/cryovex-first-results-show-sea-ice-continues-to-thin/)

https://weather.com/news/climate/news/arctic-sea-ice-april-2017-record-low (https://weather.com/news/climate/news/arctic-sea-ice-april-2017-record-low)

https://nsidc.org/arcticseaicenews/2017/05/ (https://nsidc.org/arcticseaicenews/2017/05/)

Must interesting comments in the NSIDC field report:

NSIDC scientist Julienne Stroeve continued her Arctic field work into early April, moving from Cambridge Bay, Canada to Alert in Ellesmere Island. In Alert, Stroeve focused on sampling ice thickness and snow pack characteristics along a CryoSat-2 flight track within the Lincoln Sea. This is an area between northernmost Greenland and Ellesmere Island where thick, old ice remains. The scientists flew by Twin Otter each day, out onto the sea ice between latitudes 83°N and 87.1°N. The field campaign was also supported by an aircraft from the British Antarctic Survey carrying a Ka band radar, LiDAR, and a broadband radiometer. A NASA Operation IceBridge flight also flew over the same track.

The group noted that the ice was unusually broken up and reduced to rubble, with few large multi-year floes, forcing the pilots to land on refrozen leads that at times were only 70 centimeters (28 inches) thick. Pilots remarked that they had never seen the ice look like this.

Preliminary estimates suggest mean thicknesses ranging from 2 to 3.4 meters (6.6 to 11 feet), with the thickest ice found between an ice bridge in the Lincoln Sea and mobile pack ice to the north.

Modal thickness, a representation of thermodynamically-grown level ice, ranged between 1.8 and 2.9 meters (6 and 10 feet), including 0.25 to 0.4 meters (10 to 16 inches) of snow. Second- and first-year modal ice thicknesses ranged between 1.8 and 1.9 meters (6 and 6.2 feet), about 0.2 meters (8 inches) thinner than previous airborne measurements indicated.
Title: Re: The Nares Strait thread
Post by: TenneyNaumer on May 23, 2017, 02:22:12 AM
Didn't it come from the southwestern end of the Humboldt shelf (or am I just late to the party - again!)?
https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-05-02&z=3&v=-1832652.75,-1840870.3749999995,1313075.25,-335590.37499999953 (https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-05-02&z=3&v=-1832652.75,-1840870.3749999995,1313075.25,-335590.37499999953)




The big slab in Kane basin has completed a 180 degree turn, and is now poised for head-first birth into Baffin bay.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 23, 2017, 02:52:11 AM
From Wipneus's May 9 post (http://forum.arctic-sea-ice.net/index.php/topic,176.msg112881.html#msg112881), see that Big Chunk came from west of Hulmbolt Glacier's front.  Looking at the October 1, 2016 DMI Sentinel (http://ocean.dmi.dk/arctic/kane.uk.php), there are bits of ice that got glued into the fast ice, but nothing looks very significant.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fforum.arctic-sea-ice.net%2Findex.php%3Faction%3Ddlattach%3Btopic%3D176.0%3Battach%3D45063%3Bimage&hash=52243f5caef8536de6327183e66578af)
Title: Re: The Nares Strait thread
Post by: georged on May 23, 2017, 07:27:29 AM
There is not much multi-year ice up there, and what there is is broken up with thinner lead ice in between, often less than a meter thick. Julienne Stroeve ran an ice thickness campaign to ground substantiate the Cryosat measurements along with Ice Bridge.

Here are three links:

http://blogs.esa.int/campaignearth/2017/05/01/cryovex-first-results-show-sea-ice-continues-to-thin/ (http://blogs.esa.int/campaignearth/2017/05/01/cryovex-first-results-show-sea-ice-continues-to-thin/)

https://weather.com/news/climate/news/arctic-sea-ice-april-2017-record-low (https://weather.com/news/climate/news/arctic-sea-ice-april-2017-record-low)

https://nsidc.org/arcticseaicenews/2017/05/ (https://nsidc.org/arcticseaicenews/2017/05/)

Must interesting comments in the NSIDC field report:

NSIDC scientist Julienne Stroeve continued her Arctic field work into early April, moving from Cambridge Bay, Canada to Alert in Ellesmere Island. In Alert, Stroeve focused on sampling ice thickness and snow pack characteristics along a CryoSat-2 flight track within the Lincoln Sea. This is an area between northernmost Greenland and Ellesmere Island where thick, old ice remains. The scientists flew by Twin Otter each day, out onto the sea ice between latitudes 83°N and 87.1°N. The field campaign was also supported by an aircraft from the British Antarctic Survey carrying a Ka band radar, LiDAR, and a broadband radiometer. A NASA Operation IceBridge flight also flew over the same track.

The group noted that the ice was unusually broken up and reduced to rubble, with few large multi-year floes, forcing the pilots to land on refrozen leads that at times were only 70 centimeters (28 inches) thick. Pilots remarked that they had never seen the ice look like this.

Preliminary estimates suggest mean thicknesses ranging from 2 to 3.4 meters (6.6 to 11 feet), with the thickest ice found between an ice bridge in the Lincoln Sea and mobile pack ice to the north.

Modal thickness, a representation of thermodynamically-grown level ice, ranged between 1.8 and 2.9 meters (6 and 10 feet), including 0.25 to 0.4 meters (10 to 16 inches) of snow. Second- and first-year modal ice thicknesses ranged between 1.8 and 1.9 meters (6 and 6.2 feet), about 0.2 meters (8 inches) thinner than previous airborne measurements indicated.

Thank you for this, it gives a lot of context to what's happening right now.

It's what's above Ellesmere that worries me most. The advanced transport has the potential to pull in quite a bit of surrounding ice over the next month. This year the Nares seems less like a garlic-press and more like a juicer.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 23, 2017, 05:12:16 PM
Yesterday's DMI NOAA AVHRR image shows Smith Sound very nicely. I've annotated a screenshot.
Title: Re: The Nares Strait thread
Post by: oren on May 23, 2017, 05:17:51 PM
Yesterday's DMI NOAA AVHRR image shows Smith Sound very nicely. I've annotated a screenshot.
Great image, thanks Tor
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 23, 2017, 09:57:37 PM
I just noticed the fast ice on the Greenland side of Hans Island broke between May 8 and 11, leaving the fast ice remaining on Franklin Island.  (The big floe hitting Hans Island on May 17 shattered, by the way.) (I'm making a correction on a previous Hans Is./fast ice post...)
Title: Re: The Nares Strait thread
Post by: Phil. on May 24, 2017, 03:18:30 AM
A big polynya just opened up north of the entrance to Nares st, the ice there is becoming more and more fragmented.

https://lance3.modaps.eosdis.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl1_143.A2017143201500-2017143202000.2km.jpg
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 25, 2017, 03:39:00 PM
Big Chunk appears to be disintegrating (largely) in place!  This PolarView (http://www.polarview.aq/arctic) image from yesterday has, more or less, Big Chunk circled.  I think the most solid remaining Big Chunk floe is the piece at the right end of the circled area.  Meanwhile, 'thick' Lincoln Sea ice floes are moving past at about 40 km/day (some with arrows). DMI's AQUA (http://ocean.dmi.dk/arctic/kane.uk.php) (mostly) clear sky image is from May 21.  Arrowed flows are not the same floes in the two screen prints!  (Smith Sound is about 40 km wide.)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 25, 2017, 05:36:37 PM
Cross post, for a bit of nostalgia (see Neven's message ending link to an 'old' ASIB post).
If Nares does not block up, what happens?
https://media.giphy.com/media/3oKIPiympmurT33vPO/giphy.gif (https://media.giphy.com/media/3oKIPiympmurT33vPO/giphy.gif)
Hard for me to imagine the Nares blocking up with GFS now calling for the next 5 days of significant winds occurring there. The GFS has been trending that way and it's only gotten stronger.
I don't believe I've ever seen a traffic jam in Nares Strait once the arches broke. And I've looked for it, right after starting the ASIB (see here (http://neven1.typepad.com/blog/2010/06/nares-strait-animation-part-1.html)).
Title: Re: The Nares Strait thread
Post by: Tigertown on May 25, 2017, 09:56:57 PM
Not much left now, as the remnants are dispersing.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2F&hash=35d7d5d7526c9897dfb55501e320295a)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 27, 2017, 01:11:59 PM
and a (partial) cross post showing the remnants of Big Chunk washing into Baffin Bay:
...
Here [is] ... a ... gif - the block smash in Nares strait.

I've published a bit of python code for retreiving sequences of worldview images over on the gif creation thread - it's already helpful but its just a snippet so far http://forum.arctic-sea-ice.net/index.php/topic,1259.msg114906.html#msg114906 (http://forum.arctic-sea-ice.net/index.php/topic,1259.msg114906.html#msg114906)
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fforum.arctic-sea-ice.net%2Findex.php%3Faction%3Ddlattach%3Btopic%3D1834.0%3Battach%3D45825%3Bimage&hash=54a3039c5daa8044becf7748c18b6871)
Title: Re: The Nares Strait thread
Post by: Phil. on May 27, 2017, 04:31:50 PM
Now there is a steady 'river' of fragments flowing down the west side of the strait.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on May 27, 2017, 05:05:35 PM
The triangle of what I presume is the thickest ice in the Lincoln Sea - the pale triangle along the Greenland coast (split by a long nearly-parellel-to-the-coast polynya) is quite broken up.  As these pieces (presumably) head toward Nares Strait, I do not expect them to cause any delays in export of sea ice. (PolarView  (http://bslmagb.nerc-bas.ac.uk/iwsviewer/?image=DataPolarview/111_S1jpeg2000_201705/S1B_EW_GRDM_1SDH_20170524T185509_3DB2_N_1.8bit.jp2)image from May 24 - Nares Strait's north end is in the lower left corner of screen print)
Title: Re: The Nares Strait thread
Post by: dosibl on May 27, 2017, 05:15:22 PM
Wind forecast 24 hours from now looks pretty dire on nullschool, it then proceeds to get worse. If this plays out it'll be the ultimate experiment in attempting to clog the Nares.

https://earth.nullschool.net/#2017/05/28/1500Z/wind/surface/level/orthographic=-60.36,85.27,2758/loc=-56.263,82.716 (https://earth.nullschool.net/#2017/05/28/1500Z/wind/surface/level/orthographic=-60.36,85.27,2758/loc=-56.263,82.716)
Title: Re: The Nares Strait thread
Post by: Andreas T on May 28, 2017, 10:29:36 AM
To get an idea how much ice has left the Lincoln sea into Nares strait, I have tracked some floes back to the 12th when they were at the position they had when the ice arch broke.
Title: Re: The Nares Strait thread
Post by: Phil. on May 28, 2017, 11:11:12 AM
To get an idea how much ice has left the Lincoln sea into Nares strait, I have tracked some floes back to the 12th when they were at the position they had when the ice arch broke.

That's great Andreas, it really highlights how much is leaving.  Not much sign that it's going to stop any time soon.
Title: Re: The Nares Strait thread
Post by: oren on May 28, 2017, 12:02:46 PM
Andreas - superb animation, thanks. It's amazing how the pieces break and accelerate at the entrance, like going down the drain...
Title: Re: The Nares Strait thread
Post by: bairgon on May 28, 2017, 01:57:01 PM
To get an idea how much ice has left the Lincoln sea into Nares strait, I have tracked some floes back to the 12th when they were at the position they had when the ice arch broke.

At a very rough guesstimate of area, that is a triangle with sides of 140km. That works out to around 8500km^2. The last image in the sequence is 27th May, so that is 15 days of export.

Therefore export rate is around 550 km^2 per day. That matches well with my original estimate of 500km^2:

Looking at the export over the last couple of days at start of the Robeson Channel (see gif) I estimate about 500 km^2 exported per day
Title: Re: The Nares Strait thread
Post by: Shared Humanity on May 28, 2017, 03:32:17 PM
Wind forecast 24 hours from now looks pretty dire on nullschool, it then proceeds to get worse. If this plays out it'll be the ultimate experiment in attempting to clog the Nares.

https://earth.nullschool.net/#2017/05/28/1500Z/wind/surface/level/orthographic=-60.36,85.27,2758/loc=-56.263,82.716 (https://earth.nullschool.net/#2017/05/28/1500Z/wind/surface/level/orthographic=-60.36,85.27,2758/loc=-56.263,82.716)

The Nares is open for the season. It will not clog up (if by this you mean ice not flowing south) until the next freeze season.
Title: Re: The Nares Strait thread
Post by: Andreas T on May 28, 2017, 04:47:57 PM
To get an idea how much ice has left the Lincoln sea into Nares strait, I have tracked some floes back to the 12th when they were at the position they had when the ice arch broke.

At a very rough guesstimate of area, that is a triangle with sides of 140km. That works out to around 8500km^2. The last image in the sequence is 27th May, so that is 15 days of export.

Therefore export rate is around 550 km^2 per day. That matches well with my original estimate of 500km^2:

Looking at the export over the last couple of days at start of the Robeson Channel (see gif) I estimate about 500 km^2 exported per day
I meant to do this earlier myself: the area marked with a thin yellow line on an overlay of 9th and 14th May measures 9670 km2 , so your number is a pretty close underestimate.
Although the daily rate is probably correct to allow for another day or two to let the whole marked area pass into Nares strait.
If I take the Lincoln sea as the   area below a line from the northern tip of Ellesmere to the northern tip of Greenland, then that area is 4.8 times that. (43600km2) That means it would be cleared in about three more months of going at the same rate. Just to put this into context, lets see what happens.
Title: Re: The Nares Strait thread
Post by: stackmaster on May 29, 2017, 03:25:53 AM

Just when you might have thought we reached peak shattering.

http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/201705281857.NOAA.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/201705281857.NOAA.jpg)

Title: Re: The Nares Strait thread
Post by: Shared Humanity on May 29, 2017, 03:39:55 AM
That looks really bad.
Title: Re: The Nares Strait thread
Post by: oren on May 29, 2017, 07:00:46 AM
The Lincoln Sea breakup continues in an ugly way.
On the other hand, if it drifts west this chunk of fast ice is another chance to jam the entrance to Nares, making for interesting watching before it shatters. Though I find it more probable it drifts towards the Fram instead.
Title: Re: The Nares Strait thread
Post by: bairgon on May 29, 2017, 10:05:22 AM
I've been watching this ice separating in the Kane basin recently.

That was big chunk which is no more.

Now the remains of the ice are being hammered. See Worldview (https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-05-26&z=3&v=-713845.9869392434,-1155080.7285157274,-222325.9869392434,-902920.7285157276&ab=on&as=2017-05-26&ae=2017-05-28&av=1&al=false).

Title: Re: The Nares Strait thread
Post by: FishOutofWater on May 29, 2017, 08:20:18 PM
That ice on NW Greenland was supposed to be some of the thickest sea ice in the Arctic. It's going to be down the Nares in a month or two and gone. The state of the ice in the CAA is pathetic, shattered like a high pressure vessel that exploded. The ice that usually has the most integrity in the Arctic is in fragments.
Title: Re: The Nares Strait thread
Post by: oren on May 29, 2017, 09:48:53 PM
That ice on NW Greenland was supposed to be some of the thickest sea ice in the Arctic. It's going to be down the Nares in a month or two and gone. The state of the ice in the CAA is pathetic, shattered like a high pressure vessel that exploded. The ice that usually has the most integrity in the Arctic is in fragments.
According to PIOMAS animation from a month ago, it is indeed the thickest ice in the arctic, and a bad asset to lose.
https://forum.arctic-sea-ice.net/index.php/topic,119.msg112164.html#msg112164 (https://forum.arctic-sea-ice.net/index.php/topic,119.msg112164.html#msg112164)
Title: Re: The Nares Strait thread
Post by: Tigertown on May 29, 2017, 10:02:52 PM
Warm water had most likely been working on that fast ice from below for quite some time now, and probably the whole area as far as that goes. Of course, none of the remnants left from last summer ever really got a chance to bond together properly over the winter. Plus, personally, I think all the thickness models need re-calibrated.

P.S. CMEMS shows this area as currently having the thickest ice in the Arctic at 3.85 meters at the center; very much in harmony with PIOMAS.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2F&hash=35d7d5d7526c9897dfb55501e320295a)
Title: Re: The Nares Strait thread
Post by: Andreas T on May 29, 2017, 10:49:34 PM
according to this paper  linked by Terry in the Petermann thread strong winds in Nares strait help to bring saltier and warmer water to the surface. this would explain the melting which can be seen, particularly on the Greenland side where this upwelling is said to occur.
http://muenchow.cms.udel.edu/papers/Nares2011Warming.pdf (http://muenchow.cms.udel.edu/papers/Nares2011Warming.pdf)
Title: Re: The Nares Strait thread
Post by: bairgon on May 31, 2017, 08:12:36 PM
Does the current also explain the way the ice is separating from the north of Greenland for a considerable distance? There seems to be a movement away from Fram and towards Nares, even across the far side of the northern headland on Greenland.

There was a mention recently of a current becoming established in Nares, and then being self-sustaining. If that is the case then perhaps we will see a continuous clearing of the top of Greenland throughout the summer.

Would dearly like to know what Andreas is thinking about this ATM.

Edit: Perhaps explained by the drift today: see

The ACNFS drift forecast.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 01, 2017, 05:06:33 PM
Looking at EOSDIS Worldview (https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-05-25&z=3&v=-321280.00000000104,-887039.9999999999,-160896.00000000105,-773631.9999999999) images of the Robeson Channel - Lincoln Sea portal for the past week,  it appears that on-the-order-of 300 to 500 sq. km. of ice [area] is being exported each day (27 km wide x 15-25 km movement/day x 80% concentration).  Once in Robeson Channel it speeds up and will ultimately (but not immediately) melt in southern waters.  I'm sure this is small potatoes compared with Fram Strait, but this is all ~3 meter thick ice at this time, so export is on the order of 1 cubic kilometer per day (if my presumptions and calculations are right).  The two months of 'early' Nares export (due to the Lincoln ice bridge breaking about 2 months early) may yield (roughly) 50 km3 of extra export.
Title: Re: The Nares Strait thread
Post by: bairgon on June 01, 2017, 08:30:08 PM
That's good to have independent confirmation of my earlier guess:

Assuming that we have an additional 2 month's flow through Nares compared to previous years, that is an additional 60 km^3 lost which is, very roughly, about 2-3% of the total ice volume in September.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 01, 2017, 09:55:52 PM
I now recall reading what you wrote, but didn't "use" your information when making my measurements and calculations - so it was, in fact, independent.  :)
Title: Re: The Nares Strait thread
Post by: bairgon on June 01, 2017, 11:24:45 PM
NP. It's the way science works - independent confirmation of results. I respect this forum for its scientific and facts-based approach.

There may be the odd radical theory :-)
Title: Re: The Nares Strait thread
Post by: bairgon on June 01, 2017, 11:33:55 PM
Cross post - NASA commentary on the Nares Arch:


Is there any history of this area being open... ever(in the satellite era, anyway)? Along the Greenland North coast, I mean.

I'm not really sure what the implications of it is, so I'm curious if there's anything comparable that's happened.

You can read more about the event here: https://earthobservatory.nasa.gov/IOTD/view.php?id=90245 (https://earthobservatory.nasa.gov/IOTD/view.php?id=90245)
Title: Re: The Nares Strait thread
Post by: georged on June 02, 2017, 11:53:09 AM
I've been watching this ice separating in the Kane basin recently.

That was big chunk which is no more.

Now the remains of the ice are being hammered. See Worldview (https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-05-26&z=3&v=-713845.9869392434,-1155080.7285157274,-222325.9869392434,-902920.7285157276&ab=on&as=2017-05-26&ae=2017-05-28&av=1&al=false).

Ice is being hammered all around the Greenland coast. It's quite sobering to watch such rapid disintegration within a couple of days.
Title: Re: The Nares Strait thread
Post by: Reallybigbunny on June 02, 2017, 02:07:55 PM
The ice export around Greenland is quite sensational currently! I can't see anything like it this early in the melt season in previous years! The ice is so thin it is shattering and being sucked down the Nares. A 20 mile long block is just entering Nares.
Title: Re: The Nares Strait thread
Post by: FishOutofWater on June 02, 2017, 08:32:17 PM
Thanks for the link to the paper on Nares upwelling salty warm water. I wrote about that being a likely culprit without having seen the paper. As a body surfer who has lived in California I am very aware of coastal upwelling associated with winds. The Lincoln sea and the coast of Greenland will be even more strongly affected by Eckman effects now that the ice is so mobile and the coast is clear of thick ice. The Nares must develop some very intense eddies - not a good place for your sailboat.

As I wrote before I suspect that any ice entering the Nares is going to begin melting because of the upwelling of relatively salty water. It's impossible to track the fine fragments of ice using internet evidence so I can't prove I'm right but there's good reason to think that warm water is melting ice from below in the Nares strait.
Title: Re: The Nares Strait thread
Post by: Tigertown on June 02, 2017, 09:17:12 PM
What an appetite!
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2F&hash=35d7d5d7526c9897dfb55501e320295a)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 02, 2017, 09:52:16 PM
Fish,
This upwelling warm water surely accounts for the Lincoln Sea polynya, too.  (I.e., the answer to: Why do arches form in the Lincoln Sea and not at the top end of Robeson Channel?)  The location of the sill is surely relevant to this.

(I recall some years ago seeing references to the L.S. polynya, rather than to the L.S. ice arch/bridge.)
Title: Re: The Nares Strait thread
Post by: Andreas T on June 04, 2017, 08:29:38 PM
in the last three days winds have been from the Baffin end towards the North as sen by the Automated Weather station on Hans island https://dataservices.sams.ac.uk/aws/ (https://dataservices.sams.ac.uk/aws/)
movement of ice has slowed down considerably. That it is still moving southward, although almost at a standstill from yesterday to today, must be due to water movement which is driven in part by differences in air pressure beween Baffin and Lincoln.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 08, 2017, 07:02:50 PM
I tried following a floe near the south end of Nares Strait back up to the north, but time gaps in coverage stopped me.  A few floes did dance around in Kane Basin for a few days, though.

On DMI's June 4 TERRA image of the Kennedy Channel (http://ocean.dmi.dk/arctic/kennedy.uk.php), the largest floe in the Strait was opposite Petermann Fjord.  A smaller oval floe was near Joe Island.  (Both outlined.)  On the June 7 image, the oval floe appears to remain intact, but the larger floe disintegrated, probably on Joe Island, but possibly on Hans Island.  The oval floe (presuming I have the same floe identified in the two images) went 120 km in 3 days.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 09, 2017, 03:32:43 PM
I experimented with Snagit's video ability, and made one showing Lincoln Sea ice (former Greenland fast ice) inching toward Nares Strait, and breaking up.  (DMI Terra  (http://ocean.dmi.dk/arctic/lincoln.uk.php)images from May 31, June 4 and June 8 ) [I'll remove this if it doesn't work!  It works! Yeah!!] (Note: Nares Strait is about 27 km wide at it north end.)
Title: Re: The Nares Strait thread
Post by: Chuck Yokota on June 10, 2017, 03:06:32 AM
It is very sobering to see what is supposed the oldest and thickest sea ice in the Arctic crumbling away as it moves.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 12, 2017, 04:49:29 PM
A largish floe, from the (probably) thickest former-Greenland-fast-ice is just entering Robeson Channel (northern Nares Strait).  As the winds, according to Windytv (https://www.windy.com/?80.543,-62.139,5), will generally not be supportive of a quick trip down the Nares, will this floe get stuck on Joe or Hans Islands?  The current, however, is swift:  a floe that entered Robeson Channel on June 7 or 8 (clouds...) moved 45 km between June 9 and 10 (per EOSDIS Worldview). Screen shot from PolarView (http://www.polarview.aq/arctic) - June 11, 2017 (http://bslmagb.nerc-bas.ac.uk/iwsviewer/?image=DataPolarview/111_S1jpeg2000_201706/S1A_IW_GRDH_1SDH_20170611T122423_50A7_N_1.8bit.jp2). GIF from Worldview (https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-06-10&z=3&v=-408064.3464529449,-968272.7170040049,-85248.34645294488,-719184.7170040049).
Title: Re: The Nares Strait thread
Post by: numerobis on June 13, 2017, 03:57:27 PM
LaPresse blames the cancellation of the Amundsen's mission on the failure of the Nares arch: http://www.lapresse.ca/environnement/climat/201706/13/01-5106982-les-changements-climatiques-coulent-une-mission-scientifique.php (http://www.lapresse.ca/environnement/climat/201706/13/01-5106982-les-changements-climatiques-coulent-une-mission-scientifique.php)

Quote
Des embâcles se forment habituellement au printemps dans le détroit de Nares, entre le Groenland et l'île d'Ellesmere, empêchant la banquise de descendre vers le sud. Cette année, la glace trop mince et trop molle a empêché la formation des embâcles, si bien que d'énormes quantités de glace ont descendu vers le sud, s'accumulant notamment entre l'île de Terre-Neuve et le Labrador. Voyant cela, la Garde côtière n'a eu d'autre choix que d'envoyer l'Amundsen à la rescousse, son seul brise-glace de calibre suffisant alors en état de naviguer.

(My translation): "Ice jams normally form in spring in the Nares Strait, between Greenland and Ellsmere Island, stopping the sea ice from flowing South. This year, thin and soft ice prevented the ice jams from forming, so that enormous quantities of ice flowed South, accumulating notably between the island of Newfoundland and the Labrador mainland. The Coast Guard had no choice but to send the Amundsen to the rescue, it being the Coast Guard's only operable ice breaker."

More details in the story, largely based on an interview with Barber from U.Manitoba.
Title: Re: The Nares Strait thread
Post by: Reggie on June 13, 2017, 06:10:58 PM
@numerobis

Here is a CBC english report regarding the cancellation of the science mission. Scientists measured the ice as being between 5 and 8 meters thick.


http://www.cbc.ca/news/canada/manitoba/climate-change-study-1.4157216 (http://www.cbc.ca/news/canada/manitoba/climate-change-study-1.4157216)
 
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 13, 2017, 07:25:06 PM
A largish floe, from the (probably) thickest former-Greenland-fast-ice is just entering Robeson Channel (northern Nares Strait).  As the winds, according to Windytv (https://www.windy.com/?80.543,-62.139,5), will generally not be supportive of a quick trip down the Nares, will this floe get stuck on Joe or Hans Islands?  The current, however, is swift:  a floe that entered Robeson Channel on June 7 or 8 (clouds...) moved 45 km between June 9 and 10 (per EOSDIS Worldview).
The largish floe has managed southward progress of about 12 km in 3 days (June 10-13).  The slightly smaller square-ish floe that was beside it (on its NW side) on the 10th went 90 km in those same 3 days!  This is evidence of the strong current along the Ellesmere Island coast.
Title: Re: The Nares Strait thread
Post by: Reallybigbunny on June 13, 2017, 09:53:17 PM
Great read, thanks Reggie!
Title: Re: The Nares Strait thread
Post by: Andreas T on June 13, 2017, 09:54:20 PM
The weather station on Hans island shows an interesting pattern over the last few days, it seems the wind blows either up or down the strait, quickly flipping 180 deg into the opposite direction.
https://dataservices.sams.ac.uk/aws/ (https://dataservices.sams.ac.uk/aws/)
Title: Re: The Nares Strait thread
Post by: numerobis on June 13, 2017, 10:14:08 PM
@numerobis

Here is a CBC english report regarding the cancellation of the science mission. Scientists measured the ice as being between 3 and 8 meters thick.


http://www.cbc.ca/news/canada/manitoba/climate-change-study-1.4157216 (http://www.cbc.ca/news/canada/manitoba/climate-change-study-1.4157216)

Thanks! Nice to see the two reports focus on different details of the story, they're not just bad translations of the same AP copy.
Title: Re: The Nares Strait thread
Post by: Adam Ash on June 14, 2017, 03:40:41 AM
The weather station on Hans island shows an interesting pattern over the last few days, it seems the wind blows either up or down the strait, quickly flipping 180 deg into the opposite direction.
https://dataservices.sams.ac.uk/aws/ (https://dataservices.sams.ac.uk/aws/)

'Flipping 180 degrees'?  Not quite - just going from 359 degrees to 1 degree - a 2 degree swing.  A flaw of the graph display method, not a feature of the weather!

So wind from (to?) between 240 degrees and 60 degrees. 
Title: Re: The Nares Strait thread
Post by: RikW on June 15, 2017, 08:44:20 AM
It's around 240 or around 50 degree, so almost flipping
Title: Re: The Nares Strait thread
Post by: oren on June 17, 2017, 08:47:10 AM
The high temps have caused the fast ice in fjords emptying into the strait, including Petermann, to turn a deep blue over the past couple of weeks. Tor, you should be able to see the different tinge here (I hope).
Title: Re: The Nares Strait thread
Post by: Shared Humanity on June 17, 2017, 02:31:43 PM
Snow cover has melted as well.
Title: Re: The Nares Strait thread
Post by: jai mitchell on June 17, 2017, 04:18:13 PM
LaPresse blames the cancellation of the Amundsen's mission on the failure of the Nares arch: http://www.lapresse.ca/environnement/climat/201706/13/01-5106982-les-changements-climatiques-coulent-une-mission-scientifique.php (http://www.lapresse.ca/environnement/climat/201706/13/01-5106982-les-changements-climatiques-coulent-une-mission-scientifique.php)

Quote
Des embâcles se forment habituellement au printemps dans le détroit de Nares, entre le Groenland et l'île d'Ellesmere, empêchant la banquise de descendre vers le sud. Cette année, la glace trop mince et trop molle a empêché la formation des embâcles, si bien que d'énormes quantités de glace ont descendu vers le sud, s'accumulant notamment entre l'île de Terre-Neuve et le Labrador. Voyant cela, la Garde côtière n'a eu d'autre choix que d'envoyer l'Amundsen à la rescousse, son seul brise-glace de calibre suffisant alors en état de naviguer.

(My translation): "Ice jams normally form in spring in the Nares Strait, between Greenland and Ellsmere Island, stopping the sea ice from flowing South. This year, thin and soft ice prevented the ice jams from forming, so that enormous quantities of ice flowed South, accumulating notably between the island of Newfoundland and the Labrador mainland. The Coast Guard had no choice but to send the Amundsen to the rescue, it being the Coast Guard's only operable ice breaker."

More details in the story, largely based on an interview with Barber from U.Manitoba.

I am unsure about the scale of impact, but the abnormality of much older/thicker floes into the Hudson (5-8m!!!) will cause a lower rate of SIE loss in the Northern Hemisphere graph, since these flows will persist much longer through the melt season.  However, it would also necessarily lead to more rapid losses later in the season (August cliff).
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 17, 2017, 05:42:51 PM
...Tor, you should be able to see the different tinge here (I hope).
Thanks, but I see grays and whites, not any bluishness.  Some of the difference between the two images is obviously due to clouds.  I definitely see differences in grayness in areas that appear not to have clouds in either image.  I'm gonna just trust others' sightedness!  8)
Title: Re: The Nares Strait thread
Post by: magnamentis on June 17, 2017, 05:47:24 PM
LaPresse blames the cancellation of the Amundsen's mission on the failure of the Nares arch: http://www.lapresse.ca/environnement/climat/201706/13/01-5106982-les-changements-climatiques-coulent-une-mission-scientifique.php (http://www.lapresse.ca/environnement/climat/201706/13/01-5106982-les-changements-climatiques-coulent-une-mission-scientifique.php)

Quote
Des embâcles se forment habituellement au printemps dans le détroit de Nares, entre le Groenland et l'île d'Ellesmere, empêchant la banquise de descendre vers le sud. Cette année, la glace trop mince et trop molle a empêché la formation des embâcles, si bien que d'énormes quantités de glace ont descendu vers le sud, s'accumulant notamment entre l'île de Terre-Neuve et le Labrador. Voyant cela, la Garde côtière n'a eu d'autre choix que d'envoyer l'Amundsen à la rescousse, son seul brise-glace de calibre suffisant alors en état de naviguer.

(My translation): "Ice jams normally form in spring in the Nares Strait, between Greenland and Ellsmere Island, stopping the sea ice from flowing South. This year, thin and soft ice prevented the ice jams from forming, so that enormous quantities of ice flowed South, accumulating notably between the island of Newfoundland and the Labrador mainland. The Coast Guard had no choice but to send the Amundsen to the rescue, it being the Coast Guard's only operable ice breaker."

More details in the story, largely based on an interview with Barber from U.Manitoba.

I am unsure about the scale of impact, but the abnormality of much older/thicker floes into the Hudson (5-8m!!!) will cause a lower rate of SIE loss in the Northern Hemisphere graph, since these flows will persist much longer through the melt season.  However, it would also necessarily lead to more rapid losses later in the season (August cliff).

those floes and that kind of thickness are only exceptions and as far as i can see are not present in significant amounts/numbers. hence i believe that their presence there does not have the slightest impact on any statistics with less than 2 digits after the comma.

further hudson is quite far south and mostly melts out, hence those few "bergs/floes" or whatever they are,  will mostly melt like butter later in the season as you mentioned yourself.

don't hesitate to let me know if and why you disagree with what i said, one can easily miss something, specially one who's reading and writing around 10h a day LOL
Title: Re: The Nares Strait thread
Post by: Jim Hunt on June 17, 2017, 06:28:51 PM
I am unsure about the scale of impact, but the abnormality of much older/thicker floes into the Hudson (5-8m!!!

The "older/thicker floes" aren't "into the Hudson" are they? According to the CBC report:

Quote
The icebreaker was diverted from its course to help ferries and fishing boats navigate the Strait of Belle Isle. "The requirements for search and rescue trumped the requirements for science," said Barber.

Assorted journos seem to have got hold of the wrong end of the stick.
Title: Re: The Nares Strait thread
Post by: jai mitchell on June 17, 2017, 09:10:45 PM

don't hesitate to let me know if and why you disagree with what i said, one can easily miss something, specially one who's reading and writing around 10h a day LOL

No, that sounds quite rational.  I guess I am also conflating the perception of much older and thicker ice from the Fram, as reported by Icebridge in (May?) 
Title: Re: The Nares Strait thread
Post by: Andreas Muenchow on June 17, 2017, 11:19:07 PM
The thickest ice off Labrador and Newfoundland (excluding icebergs) originates mostly in the Lincoln Sea and passes south through Nares Strait. We observed ice draft every 10 seconds from 2003 through 2012 and ice thicker than 5-m occurs, but is very rare, about 5% of the time. The peer reviewed paper is at

http://muenchow.cms.udel.edu/papers/RyanMuenchow2017.pdf (http://muenchow.cms.udel.edu/papers/RyanMuenchow2017.pdf)

 
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 18, 2017, 12:41:47 AM
Thanks for your paper, Andreas [http://muenchow.cms.udel.edu/papers/RyanMuenchow2017.pdf (http://muenchow.cms.udel.edu/papers/RyanMuenchow2017.pdf)]  It puts real (previous year) numbers to my speculations of this spring's ice export in this thread!

I'm sure the thick ice floes seen near Labrador got there before the Lincoln Sea ice bridge formed in early February 2017 (that broke in early May), but how long before, I wonder - October-November 2016?
Title: Re: The Nares Strait thread
Post by: magnamentis on June 18, 2017, 02:21:08 AM
The thickest ice off Labrador and Newfoundland (excluding icebergs) originates mostly in the Lincoln Sea and passes south through Nares Strait. We observed ice draft every 10 seconds from 2003 through 2012 and ice thicker than 5-m occurs, but is very rare, about 5% of the time. The peer reviewed paper is at

http://muenchow.cms.udel.edu/papers/RyanMuenchow2017.pdf (http://muenchow.cms.udel.edu/papers/RyanMuenchow2017.pdf)

thanks a lot, very helpful, sheds some light for me and others who are not extremely privy with that.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 19, 2017, 08:34:01 PM
A largish floe, from the (probably) thickest former-Greenland-fast-ice is just entering Robeson Channel (northern Nares Strait).  As the winds, according to Windytv (https://www.windy.com/?80.543,-62.139,5), will generally not be supportive of a quick trip down the Nares, will this floe get stuck on Joe or Hans Islands?  ...
This 'largish floe', apparently, bumped the Greenland coast upon entering Robeson Channel and broke.  The largest piece has passed Joe Island (near the mouth of Petermann Fjord) and is making its way south, probably a couple days away from Hans Island.  It looks like it could slip by, but it will probably hit poor Hans.  If Andreas's recording devices remain pointing up from the Kennedy Channel depths, we may some day know how thick this floe is (was)!
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 21, 2017, 04:42:24 PM
We may know this afternoon (eastern North America time) how intact 'largish floe' remains after its (at least) close encounter with Hans Island.  (Yesterday's DMI (http://ocean.dmi.dk/arctic/kennedy.uk.php) Sentinel image annotated screen print of Kennedy Channel)
Title: Re: The Nares Strait thread
Post by: Phil. on June 21, 2017, 04:49:11 PM
We may know this afternoon (eastern North America time) how intact 'largish floe' remains after its (at least) close encounter with Hans Island.  (Yesterday's DMI (http://ocean.dmi.dk/arctic/kennedy.uk.php) Sentinel image annotated screen print of Kennedy Channel)

Right now it appears to be jammed up against the island but still intact according to MODIS.

https://lance3.modaps.eosdis.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2017172084000-2017172084500.250m.jpg
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 21, 2017, 06:10:02 PM
Yup (I rotated [then cropped] a screen print from Phil's link - and it is now afternoon here  ;D)
Title: Re: The Nares Strait thread
Post by: Clenchie on June 21, 2017, 07:33:08 PM
Yup (I rotated [then cropped] a screen print from Phil's link - and it is now afternoon here  ;D)

It is further down now.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 21, 2017, 08:13:46 PM
Looks pretty intact, lucky floe!  By the way:  thanks Clenchie and Phil for watching.

(The floes actively approaching Nares Strait in the Lincoln Sea are all pretty small already.  The largest floes in the Lincoln Sea are hugging the Greenland coast and appear to be (temporarily) frozen in place.)
Title: Re: The Nares Strait thread
Post by: gerontocrat on June 21, 2017, 09:00:33 PM
Is Hans Island a lump of solid rock or is it just a heap of accumulated glacial debris ?
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 21, 2017, 09:05:57 PM
Quote
Hans Island is interesting to geologists because it's part of a mountain chain that starts in the Svalbard Islands off Norway, runs through Greenland, and pokes out again in Ellesmere Island.Apr 9, 2004
Greenland, Canada squabbling over pet rock - Nunatsiaq News
www.nunatsiaqonline.ca/archives/40409/news/nunavut/40409_08.html (http://www.nunatsiaqonline.ca/archives/40409/news/nunavut/40409_08.html)
That is:  it is solid rock.
Title: Re: The Nares Strait thread
Post by: gerontocrat on June 21, 2017, 09:15:53 PM
Quote
Hans Island is interesting to geologists because it's part of a mountain chain that starts in the Svalbard Islands off Norway, runs through Greenland, and pokes out again in Ellesmere Island.Apr 9, 2004
Greenland, Canada squabbling over pet rock - Nunatsiaq News
www.nunatsiaqonline.ca/archives/40409/news/nunavut/40409_08.html (http://www.nunatsiaqonline.ca/archives/40409/news/nunavut/40409_08.html)
That is:  it is solid rock.

Given its position obstructing traffic on the Nares Strait Lincoln Sea Ice Motorway (Autostrada, Freeway) is there any data regarding its diminuition in size due to frequent collisions with self-driving lumps of ice ?
Title: Re: The Nares Strait thread
Post by: johnm33 on June 21, 2017, 09:35:50 PM
Looks like a little more ice is about to break from Humbolt, new moon on the 24th should get it moving south.
(https://puu.sh/wqFkh/a5e5fa7545.jpg)
Title: Re: The Nares Strait thread
Post by: Phil. on June 22, 2017, 02:50:43 PM
Looks pretty intact, lucky floe!  By the way:  thanks Clenchie and Phil for watching.

(The floes actively approaching Nares Strait in the Lincoln Sea are all pretty small already.  The largest floes in the Lincoln Sea are hugging the Greenland coast and appear to be (temporarily) frozen in place.)

That floe has now made it unscathed past the two islands now. It seems that the ice near the entrance to the strait in the Lincoln sea has broken up into fairly small fragments compared with a week or so ago.

https://lance3.modaps.eosdis.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2017173074500-2017173075000.250m.jpg
Title: Re: The Nares Strait thread
Post by: Clenchie on June 22, 2017, 03:52:01 PM
Looks pretty intact, lucky floe!  By the way:  thanks Clenchie and Phil for watching.

(The floes actively approaching Nares Strait in the Lincoln Sea are all pretty small already.  The largest floes in the Lincoln Sea are hugging the Greenland coast and appear to be (temporarily) frozen in place.)

That floe has now made it unscathed past the two islands now. It seems that the ice near the entrance to the strait in the Lincoln sea has broken up into fairly small fragments compared with a week or so ago.

https://lance3.modaps.eosdis.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2017173074500-2017173075000.250m.jpg

It is surprising how fast such a large floe can proceed down the channel.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 22, 2017, 07:02:52 PM
...
Given [Hans Island's] position obstructing traffic on the Nares Strait Lincoln Sea Ice Motorway (Autostrada, Freeway) is there any data regarding its diminuition in size due to frequent collisions with self-driving lumps of ice ?
I expect one might feel some of those lumps of ice hitting the island, but they will have a tiny affect on its size.  The Ice Age glaciers that carved Nares Strait continually dragged a giant's equivalent of sandpaper against it, and were able to put a lot of umph into their work, yet "decided" to leave its remnants alone.  But the way, it is composed of Silurian aged limestone, per this  1931 map (via Geo. Survey of Denmark) (http://www.geus.dk/DK/publications/geol-survey-dk-gl-bull/15/Documents/nr15_p77-80.pdf)
(Interesting that Petermann Fjord had a different name then.)
Title: Re: The Nares Strait thread
Post by: Clenchie on June 22, 2017, 07:16:17 PM
...
Given [Hans Island's] position obstructing traffic on the Nares Strait Lincoln Sea Ice Motorway (Autostrada, Freeway) is there any data regarding its diminuition in size due to frequent collisions with self-driving lumps of ice ?
I expect one might feel some of those lumps of ice hitting the island, but they will have a tiny affect on its size.  The Ice Age glaciers that carved Nares Strait continually dragged a giant's equivalent of sandpaper against it, and were able to put a lot of umph into their work, yet "decided" to leave its remnants alone.  But the way, it is composed of Silurian aged limestone, per this  1931 map (via Geo. Survey of Denmark) (http://www.geus.dk/DK/publications/geol-survey-dk-gl-bull/15/Documents/nr15_p77-80.pdf)
(Interesting that Petermann Fjord had a different name then.)

(https://upload.wikimedia.org/wikipedia/commons/c/ca/HansIsland.png)
It doesn't look that high so I guess it will one day be below sea level. Thanks to Tor Bejnar for pointing out the height is 150m - 170m, which means that it will remain above sea level even if the most pessimistic sea level predictions are manifested.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 22, 2017, 07:56:32 PM
From the first paragraph of the above referenced Geo. Survey of Denmark paper:
Quote
... Rising less than 170 m above normally ice-infested waters, the 1.25 km2 island is physiographically far overshadowed by nearby Franklin Ø (Fig. 1).

Referencing "Government of Canada, (1985) Sailing Directions, Arctic Canada, Vol. 2, Ottawa: Canadian Hydrographic Service", this Canada's Unresolved maritime Boundaries (https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=13&ved=0ahUKEwi27bezhdLUAhVG0iYKHc4lAxg4ChAWCCowAg&url=https%3A%2F%2Fwww.dur.ac.uk%2Fibru%2Fpublications%2Fdownload%2F%3Fid%3D115&usg=AFQjCNHjQZXOny6w6xBq68Py3-qbIxHFuQ&cad=rja) paper) reports:
Quote
Hans Island (80° 49’N, 66° 28’W) is described as being sandy in colour with a cliff at its south end of about 150m in elevation.
  This would be the height of the cliff.

Finally, from Hans Island: Meteorological Data From an International Borderline (http://www-po.coas.oregonstate.edu/~rms/ms/2009EO220002.pdf):
Quote
Hans Island (80º49’35’N, 66º27’35’W) is a small sandstone landform that occupies an area of about 1.3 square kilometers and is 168 meters in height (Figure 1a).
"Sandstone"  Hmmmm.
Title: Re: The Nares Strait thread
Post by: gerontocrat on June 22, 2017, 08:49:39 PM
From the first paragraph of the above referenced Geo. Survey of Denmark paper:
Quote
... Rising less than 170 m above normally ice-infested waters, the 1.25 km2 island is physiographically far overshadowed by nearby Franklin Ø (Fig. 1).

Referencing "Government of Canada, (1985) Sailing Directions, Arctic Canada, Vol. 2, Ottawa: Canadian Hydrographic Service", this Canada's Unresolved maritime Boundaries (https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=13&ved=0ahUKEwi27bezhdLUAhVG0iYKHc4lAxg4ChAWCCowAg&url=https%3A%2F%2Fwww.dur.ac.uk%2Fibru%2Fpublications%2Fdownload%2F%3Fid%3D115&usg=AFQjCNHjQZXOny6w6xBq68Py3-qbIxHFuQ&cad=rja) paper) reports:
Quote
Hans Island (80° 49’N, 66° 28’W) is described as being sandy in colour with a cliff at its south end of about 150m in elevation.
  This would be the height of the cliff.

Finally, from Hans Island: Meteorological Data From an International Borderline (http://www-po.coas.oregonstate.edu/~rms/ms/2009EO220002.pdf):
Quote
Hans Island (80º49’35’N, 66º27’35’W) is a small sandstone landform that occupies an area of about 1.3 square kilometers and is 168 meters in height (Figure 1a).
"Sandstone"  Hmmmm.
Looks more like dolomite to me. That horizontal stratigraphy also reminiscent of periodic deposits of calcium carbonate in shallow warm seas?
Title: Re: The Nares Strait thread
Post by: RoxTheGeologist on June 22, 2017, 09:30:46 PM
Looks like its limestone and dolomites

Its old! Silurian, and not metamorphosed, which illustrated how stable the shield has been.

Ludlovian in age (named after the original type locality of Ludlow, Shropshire)

Tectonic setting is of a continental margin.


Kap Morton Formation (M)
Name. Hurst (1980a).
Other literature. Hurst (1981), Peel (1984), de Freitas
et al. (1993).
Age. Middle to Late Silurian.
Thickness and lithology. This map unit of shallowly
dipping, well-bedded, mainly pale carbonates, about
450 m thick, occurs on the west side of John Brown
Iskappe overlying map unit G, and forms the c. 200 m
succession on Hans Ø in mid-Kennedy Channel. It
corresponds to the Kap Morton Formation of Hurst
(1980a), but also includes strata referred to the Kap
Godfred Hansen and Pentamerus Bjerge Formations
(see Hurst 1980a, figs 24, 28). In the highest ground
fringing the ice cap, it includes a stratal interval that
probably equates with the Kap Maynard Formation (Fig.
38
20). Described in the literature mainly from sections
north of the map sheet, the lower part of the map unit
comprises massive, light grey, lime mudstones with
incursions of bioclastic limestone and resedimented
carbonate conglomerate. On Hans Ø, where the section
is characterised by alternating pale and darker
carbonates that are in part dolomitised, a pinnacle reef
occurs together with stromatoporoid- and coral-rich
biostromal beds (see de Freitas et al. 1993, fig. 7). The
lime mudstones, both in Washington Land and on Hans
Ø, are characterised by articulate megalodont bivalves
(see Hurst 1980a, fig. 50; de Freitas 1990, fig. 2; de
Freitas et al. 1993, fig. 4). The lithology of the upper
part of the map unit is poorly known, but on aerial
photographs it has the same well-layered character as
the lower strata, and to the succession north of the
map sheet referred by Hurst (1980a) and Jepsen et al.
(1983) to the Kap Maynard Formation. The Hans Ø
succession, with its Ludlow fauna, was referred to the
Kap Maynard Formation by de Freitas et al. (1993, fig.
5), but is placed here in the Kap Morton Formation.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 22, 2017, 09:57:52 PM
Thanks, Rox!
From the Canadian geological map of the Arctic (http://geoscan.nrcan.gc.ca/starweb/geoscan/servlet.starweb?path=geoscan/downloade.web&search1=R=287868), here is a screen shot of the Kennedy Channel area.  The added red arrow points to about where Hans Island would be.  Franklin Island is shown, and is colored a 'green' that is identified "S4" elsewhere.  The legend identifies "S4" as being Silurian carbonates.
Title: Re: The Nares Strait thread
Post by: gerontocrat on June 22, 2017, 10:04:00 PM
Being a mixture of limestone and domolitised limestone, Hans Island will be there for a very long time after there is no ice left to wear it away. But it was nice to see that some of the geology I learnt 50 years ago is still lurking in forgotten areas of the cerebrum.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 23, 2017, 02:45:29 PM
cross post:
Perhaps this is obvious, but I haven't seen it mentioned that every chunk of ice exported through the Fram or elsewhere into warmer non-arctic waters is equivalent to the latent heat necessary to melt that ice imported directly to the arctic ice. According to this paper
http://www.the-cryosphere.net/11/65/2017/ (http://www.the-cryosphere.net/11/65/2017/)
export has since 1935 averaged about 880,000 km2 or roughly 10% of the yearly decline, but has been trending up by 6% per decade since 1979 (11% during summers). Given the condition of the ice I wonder  if  the cloudier stormier weather might cause a big change this year.
It's also worth noting that  export throught Nares, when the arches do not form, adds about 5% to the normal export so we can expect to see an additional 150 Km^2 going out through Nares this year.
Title: Re: The Nares Strait thread
Post by: FishOutofWater on June 23, 2017, 03:29:57 PM
The addition of the recent paper by Andreas was very informative. I was relieved to see my speculation that this winter's ice arc in the Lincoln sea led to upwelling along the Greenland side of the Nares strait, and salinization of the water by means of the formation of new ice was consistent with his expert analysis.

The conclusion that we are observing a transition during which the last thick mullti-year ice leaves the arctic is disturbing but something I think we have been aware of for some time. Watching the thick land fast ice in the Lincoln sea break off the Greenland shore and pass down the strait is very disturbing because of the speed of the transition. In a few weeks huge thick blocks of ice have shattered into small fragments that will all pass Hans island before summer is over.

It's interesting to know that Hans island was part of a sedimentary basin that was once continuous to Svalbard but has since been rifted apart by the opening of the far north Atlantic and Arctic basins.

After the passage of hundreds of millions of years, the rifting and Pleistocene glaciation, Hans island is still a flat layered shallow sea floor unmetamorphosed carbonate sequence relatively undisturbed by the passage of so much time... an island of stability in a sea of change.
Title: Re: The Nares Strait thread
Post by: gerontocrat on June 23, 2017, 04:23:58 PM
HANS ISLAND:-
Totally off-topic, but will the Guv'nor kill a poem? This is a poem by Kay Kendall (January 1885) mocking Darwin's Origin of Species. I could not resist it.

The Lay of the Trilobite
A mountain’s giddy height I sought,
Because I could not find
Sufficient vague and mighty thought
To fill my mighty mind;
And as I wandered ill at ease,
There chanced upon my sight
A native of Silurian seas,
An ancient Trilobite.

So calm, so peacefully he lay,
I watched him even with tears:
I thought of Monads far away
In the forgotten years.
How wonderful it seemed and right,
The providential plan,
That he should be a Trilobite,
And I should be a Man!

And then, quite natural and free
Out of his rocky bed,
That Trilobite he spoke to me
And this is what he said:
‘I don’t know how the thing was done,
Although I cannot doubt it;
But Huxley – he if anyone
Can tell you all about it;

‘How all your faiths are ghosts and dreams,
How in the silent sea
Your ancestors were Monotremes –
Whatever these may be;
How you evolved your shining lights
Of wisdom and perfection
From Jelly-Fish and Trilobites
By Natural Selection.

‘You’ve Kant to make your brains go round,
Hegel you have to clear them,
You’ve Mr Browning to confound,
And Mr Punch to cheer them!
The native of an alien land
You call a man and brother,
And greet with hymn-book in one hand
And pistol in the other!

‘You’ve Politics to make you fight
As if you were possessed:
You’ve cannon and you’ve dynamite
To give the nations rest:
The side that makes the loudest din
Is surest to be right,
And oh, a pretty fix you’re in!’
Remarked the Trilobite.

‘But gentle, stupid, free from woe
I lived among my nation,
I didn’t care – I didn’t know
That I was a Crustacean.*
I didn’t grumble, didn’t steal,
I never took to rhyme:
Salt water was my frugal meal,
And carbonate of lime.’

Reluctantly I turned away,
No other word he said;
An ancient Trilobite, he lay
Within his rocky bed.
I did not answer him, for that
Would have annoyed my pride:
I merely bowed, and raised my hat,
But in my heart I cried: –

‘I wish our brains were not so good,
I wish our skulls were thicker,
I wish that Evolution could
Have stopped a little quicker;
For oh, it was a happy plight,
Of liberty and ease,
To be a simple Trilobite
In the Silurian seas!’
Title: Re: The Nares Strait thread
Post by: bairgon on June 24, 2017, 07:46:14 AM
Some time back I asked this question:

I was also struck but what appear to be a line of fixed items across (Kane) basin. Are there small islands here?

Finally found the answer. They are grounded calved icebergs from the nearby glacier. The Sentinel playground shows them clearly here (http://apps.sentinel-hub.com/sentinel-playground/?lat=79.76751177474232&lng=-65.2532958984375&zoom=10&preset=CUSTOM&layers=B8A,B03,B02&maxcc=100&gain=0.4&gamma=1.0&time=2015-01-01|2017-06-22&cloudCorrection=none&atmFilter=&showDates=false&evalscript=).
Title: Re: The Nares Strait thread
Post by: johnm33 on June 24, 2017, 08:38:18 AM
There appears to be a huge outflow of water beneath Humbolt
(https://puu.sh/wsOqy/d9cc4d5d1f.jpg)
from https://www7320.nrlssc.navy.mil/GLBhycomcice1-12/navo/arcticsss_nowcast_anim30d.gif
and the cracks are expanding and showing up on the Glacier not just the fast ice
(https://puu.sh/wsOED/38890283e0.jpg)
best to click on bairgons link zoom in and look around, the cracks look ominous to me but maybe they're just streams.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 24, 2017, 02:44:22 PM
Kane Basin is deep; there are no grounded icebergs in its middle.  See this post (from May 12) for bathymetry of Kane Basin (http://forum.arctic-sea-ice.net/index.php/topic,176.msg113321.html#msg113321).  There is a Kane Basin Gyre (http://forum.arctic-sea-ice.net/index.php/topic,176.msg113368.html#msg113368) that keeps ice in its middle for several days.

What looks like ominous cracks in Humboldt Glacier (next to Kane Basin) are river beds (per attached screen print 'enlargement' from bairgon's Sentinel Playground link (http://apps.sentinel-hub.com/sentinel-playground/?lat=79.14637663571963&lng=-65.423583984375&zoom=12&preset=CUSTOM&layers=B8A,B03,B02&maxcc=100&gain=0.4&gamma=1.0&time=2015-01-01|2017-06-22&cloudCorrection=none&atmFilter=&showDates=false&evalscript=)).
Title: Re: The Nares Strait thread
Post by: bairgon on June 24, 2017, 03:09:40 PM
Kane Basin is deep; there are no grounded icebergs in its middle.

The bathymetry that you referenced only covers the south-western end of the basin.

Do you have another explanation for the static elements in this gif below?
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 24, 2017, 04:02:04 PM
I do not have an explanation for those static white 'spots' on that animation.  (Your May 29 post (http://forum.arctic-sea-ice.net/index.php/topic,176.msg115176.html#msg115176) shows them well.) They might be grounded ice, after all.

To further this exploration, I start with this May 22 post (http://forum.arctic-sea-ice.net/index.php/topic,176.msg114468.html#msg114468) that draws from Wipneus's May 9 post (http://forum.arctic-sea-ice.net/index.php/topic,176.msg112881.html#msg112881) (with enlarged GIF - with click) showing nothing grounded beyond the fast ice off Humboldt Glacier, at least where "Big Chuck" started.  The static white spots, however, may be a little bit north of where "Big Chunk" started.  [Alas, I have other things I have to do, so I'm stopping now.]
Title: Re: The Nares Strait thread
Post by: Phil. on June 24, 2017, 06:29:50 PM
Looks pretty intact, lucky floe!  By the way:  thanks Clenchie and Phil for watching.

(The floes actively approaching Nares Strait in the Lincoln Sea are all pretty small already.  The largest floes in the Lincoln Sea are hugging the Greenland coast and appear to be (temporarily) frozen in place.)

That floe has now made it unscathed past the two islands now. It seems that the ice near the entrance to the strait in the Lincoln sea has broken up into fairly small fragments compared with a week or so ago.

https://lance3.modaps.eosdis.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2017173074500-2017173075000.250m.jpg

It is surprising how fast such a large floe can proceed down the channel.

Indeed, the fragment we were talking about is now about 55 miles south of Franklin Island.
Title: Re: The Nares Strait thread
Post by: Clenchie on June 24, 2017, 07:35:08 PM
Looks pretty intact, lucky floe!  By the way:  thanks Clenchie and Phil for watching.

(The floes actively approaching Nares Strait in the Lincoln Sea are all pretty small already.  The largest floes in the Lincoln Sea are hugging the Greenland coast and appear to be (temporarily) frozen in place.)

That floe has now made it unscathed past the two islands now. It seems that the ice near the entrance to the strait in the Lincoln sea has broken up into fairly small fragments compared with a week or so ago.

https://lance3.modaps.eosdis.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2017173074500-2017173075000.250m.jpg

It is surprising how fast such a large floe can proceed down the channel.

Indeed, the fragment we were talking about is now about 55 miles south of Franklin Island.

The distinctive shape makes it easy to track.  Hopefully it is thick enough to remain intact and survive for another winter, currents allowing.
Title: Re: The Nares Strait thread
Post by: Reggie on June 26, 2017, 02:48:56 AM
CFS Alert, Nunavut @ Latitude 82.52° N | Longitude 62.28° W had a high today of 11C and sustained winds exceeding 50k/hr. Worldview June 25th image for the Lincoln Sea reflects the past two days winds and temperatures.

Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 26, 2017, 05:23:31 AM
All the ice in the Lincoln Sea (including what is in the north end of Nares Strait [not off topic ::)] has been blown east- or northeastwasd between yesterday and today, per DMI (http://ocean.dmi.dk/arctic/lincoln.uk.php) Sentinel images, even the remaining (what I presume to be) thick ice just north of Greenland that had frozen in place for a few days.  Windytv (https://www.windy.com/?82.150,-60.205,6)'s now-cast (screen print shown below) and forecasts of winds supports continued movement northwards for a few days.
Title: Re: The Nares Strait thread
Post by: Phil. on June 26, 2017, 01:35:28 PM
Looks pretty intact, lucky floe!  By the way:  thanks Clenchie and Phil for watching.

(The floes actively approaching Nares Strait in the Lincoln Sea are all pretty small already.  The largest floes in the Lincoln Sea are hugging the Greenland coast and appear to be (temporarily) frozen in place.)

That floe has now made it unscathed past the two islands now. It seems that the ice near the entrance to the strait in the Lincoln sea has broken up into fairly small fragments compared with a week or so ago.

https://lance3.modaps.eosdis.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2017173074500-2017173075000.250m.jpg

It is surprising how fast such a large floe can proceed down the channel.

Indeed, the fragment we were talking about is now about 55 miles south of Franklin Island.

The distinctive shape makes it easy to track.  Hopefully it is thick enough to remain intact and survive for another winter, currents allowing.

Now it's about 83 miles south of Franklin.
Title: Re: The Nares Strait thread
Post by: Clenchie on June 28, 2017, 01:25:00 PM
Looks pretty intact, lucky floe!  By the way:  thanks Clenchie and Phil for watching.

(The floes actively approaching Nares Strait in the Lincoln Sea are all pretty small already.  The largest floes in the Lincoln Sea are hugging the Greenland coast and appear to be (temporarily) frozen in place.)

That floe has now made it unscathed past the two islands now. It seems that the ice near the entrance to the strait in the Lincoln sea has broken up into fairly small fragments compared with a week or so ago.

https://lance3.modaps.eosdis.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2017173074500-2017173075000.250m.jpg

It is surprising how fast such a large floe can proceed down the channel.

Indeed, the fragment we were talking about is now about 55 miles south of Franklin Island.

The distinctive shape makes it easy to track.  Hopefully it is thick enough to remain intact and survive for another winter, currents allowing.

Now it's about 83 miles south of Franklin.

It has kept its distinctive bell shape and drifted into the centre of the channel.
Title: Re: The Nares Strait thread
Post by: oren on June 28, 2017, 04:45:40 PM
It has kept its distinctive bell shape and drifted into the centre of the channel.
For the sake of readability, may I suggest when quoting a chain of quotes, to edit and use just the last quote or the relevant part.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 28, 2017, 04:57:02 PM
"It has kept its distinctive bell shape and drifted into the centre of the channel."

I've been wanting to call it the "Bell Floe" since before Hans Island, but I refrained myself as I enjoy using names derived from other's observations.  the Sentinel images show some curved texture that suggests it is a 3-D object and not a functionally flat floe.  Screen shots from DMI (http://ocean.dmi.dk/arctic/kane.uk.php) Sentinel & AQUA, both dated 2017-06-27
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 28, 2017, 05:57:33 PM
The ice that had been blown away from the Elsmere Island coast (June 26 image) came back (June 27 image) (video screen shot from DMI-Sentinel (http://ocean.dmi.dk/arctic/lincoln.uk.php))  Floes are again entering the Robeson Channel.
Title: Re: The Nares Strait thread
Post by: Clenchie on June 28, 2017, 06:36:04 PM
Quote
For the sake of readability, may I suggest when quoting a chain of quotes, to edit and use just the last quote or the relevant part.

Apologies, I thought the protocol was to leave a complete trail.  Will edit selectively in future.
Title: Re: The Nares Strait thread
Post by: Clenchie on June 28, 2017, 06:44:45 PM
Quote
I've been wanting to call it the "Bell Floe" since before Hans Island, but I refrained myself as I enjoy using names derived from other's observations.  the Sentinel images show some curved texture that suggests it is a 3-D object and not a functionally flat floe.  Screen shots from DMI (http://ocean.dmi.dk/arctic/kane.uk.php) Sentinel & AQUA, both dated 2017-06-27

It was either a bell or a Darth Vader mask so I plumped for brevity.  Interesting that you have discovered a curved texture on the North West sector of the floe.  Maybe we could get a 3d render at some point.  It looks to be only about 120km from Thule airbase - could be filmed from the air!

I have taken the liberty of juxtaposing two pictures that illustrate the rotation of the floe as it passes down the channel.  The first is from 19th June up by the Petermann glacier, the second is yesterday in the Kane Basin.

Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 28, 2017, 07:29:44 PM
I also like the white fringe along the [would-be] 'open' edge of the bell on the Sentinel images.

Given the 'Bell Floe' is in Kane Basin and has wandered away from the Elsmere coast, it is liable to get caught up in the Kane Basin Gyre and remain there awhile.
Title: Re: The Nares Strait thread
Post by: Phil. on June 30, 2017, 05:44:13 PM
I also like the white fringe along the [would-be] 'open' edge of the bell on the Sentinel images.

Given the 'Bell Floe' is in Kane Basin and has wandered away from the Elsmere coast, it is liable to get caught up in the Kane Basin Gyre and remain there awhile.

It's actually been balanced on a cluster of floes stuck on the Greenland side for a couple of days at 79º30' N 70ºW.  Looks like a good puff of wind would shift it though.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 30, 2017, 06:41:32 PM
"Balanced"?  Viewing successive EOSDIS Worldview (https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-06-29&z=3&v=-688388.6292277403,-1165239.7638481655,-321284.62922774034,-916151.7638481656) images (from June 21), the Bell Floe has moved at least 15 km each day until yesterday (between June 28 and 29 [video below]) when one corner of it moved only a few km (northward).  With wind out of the north (per Windytv (https://www.windy.com/?80.543,-62.139,5)'s now-cast, at least), this northward movement of the floe would be due to the gyre.  Smaller floes in the area aren't moving much.  (There are a few quite small floes (bergs?) near the lower right corner of this animation that don't move, including a "" shaped one.) [Bell Floe is about 15 km wide.]
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 30, 2017, 07:39:12 PM
The (what I believe to be) oldest ice in the Lincoln Sea is now a cluster of large floes.  Sentinel images (via DMI (http://ocean.dmi.dk/arctic/lincoln.uk.php)) show this ice to be recently broken on June 5, moved southwestward on June 17 and moved (at least most of it) about half-way back on June 28.  Ice in the eastern part of Lincoln Sea continues (but not continuously so) to feed Nares Strait.  (3-date movie is from upper right part of area screen shot.)
Title: Re: The Nares Strait thread
Post by: Clenchie on June 30, 2017, 08:59:05 PM
(There are a few quite small floes (bergs?) near the lower right corner of this animation that don't move, including a "" shaped one.) [Bell Floe is about 15 km wide.]

Those look to be either land masses or glitches on the image because they don't move one iota despite all the movement around them.  I have tried to enlarge the image but all I get is large pixels, without definition enough to discern their true nature.  They are very small.  I wonder if there is someone with more detailed knowledge of the waters in that area, or maybe access to images with better resolution.

Update:  if you go to 24th September 2015 you will see something in the exact same spot that doesn't move in the days either side.  There is more ice but the same spot is there.
Title: Re: The Nares Strait thread
Post by: bairgon on July 01, 2017, 01:04:19 AM
(There are a few quite small floes (bergs?) near the lower right corner of this animation that don't move, including a "" shaped one.) [Bell Floe is about 15 km wide.]

Those look to be either land masses or glitches on the image because they don't move one iota despite all the movement around them.  I have tried to enlarge the image but all I get is large pixels, without definition enough to discern their true nature.  They are very small.  I wonder if there is someone with more detailed knowledge of the waters in that area, or maybe access to images with better resolution.

Update:  if you go to 24th September 2015 you will see something in the exact same spot that doesn't move in the days either side.  There is more ice but the same spot is there.

As I stated a little while ago, with a link to Sentinel which shows much better resolution:

Finally found the answer. They are grounded calved icebergs from the nearby glacier. The Sentinel playground shows them clearly here (http://apps.sentinel-hub.com/sentinel-playground/?lat=79.76751177474232&lng=-65.2532958984375&zoom=10&preset=CUSTOM&layers=B8A,B03,B02&maxcc=100&gain=0.4&gamma=1.0&time=2015-01-01|2017-06-22&cloudCorrection=none&atmFilter=&showDates=false&evalscript=).

I found a reference to the Humboldt Glacier calving front being up to 50m high. That would give a considerable depth below water. As the icebergs are in lines I expect there are some old sills at that end of Kane basin.
Title: Re: The Nares Strait thread
Post by: bairgon on July 01, 2017, 08:21:37 AM
Finally found the answer. They are grounded calved icebergs from the nearby glacier. The Sentinel playground shows them clearly here (http://apps.sentinel-hub.com/sentinel-playground/?lat=79.76751177474232&lng=-65.2532958984375&zoom=10&preset=CUSTOM&layers=B8A,B03,B02&maxcc=100&gain=0.4&gamma=1.0&time=2015-01-01|2017-06-22&cloudCorrection=none&atmFilter=&showDates=false&evalscript=).

I found a sequence near the bell floe on Sentinel - at this link (http://apps.sentinel-hub.com/sentinel-playground/?lat=79.69412709553619&lng=-68.03266525268555&zoom=13&preset=CUSTOM&layers=B8A,B03,B02&maxcc=100&gain=0.4&gamma=1.0&time=2015-01-01|2017-06-29&cloudCorrection=none&atmFilter=&showDates=false&evalscript=) - that shows this very clearly.

The GIF below starts at 16th June and skips cloudy days. The last image is the last available, from 29th June.

Points to note: watch the triangular-shaped iceberg at top right. It moves a little, seems to get stuck, and then gets knocked out of position by some sea ice and appears at bottom left. You can also see another square-ish iceberg which moves out of the original line but ends up stuck despite the sea ice coming through.

Also note the difference in the colouring. The sea ice is clearly covered in melt ponds, but the icebergs stay gray presumably because they are not flat. I've put in a nice shot at full resolution illustrating this from 27th June.

Edit: corrected left/right; and note that the triangular iceberg is around 300m long.
Title: Re: The Nares Strait thread
Post by: oren on July 01, 2017, 08:50:50 AM
Thanks bairgon, great animation and explanation.
Title: Re: The Nares Strait thread
Post by: Clenchie on July 01, 2017, 06:36:21 PM
Thanks bairgon, great animation and explanation.

Yes Bairgs, your theory has great merit.  The underwater obstructions must wreak havoc with the ice and cause chaotic flow patterns.
Title: Re: The Nares Strait thread
Post by: bairgon on July 01, 2017, 11:05:01 PM
the shadow of the main branch looks like it will allow the estimation of the calving front height via using incidence angle & sun elevation angle at the time of imaging...

Looking at the calving front  (http://apps.sentinel-hub.com/sentinel-playground/?lat=79.78977917836382&lng=-64.44889068603516&zoom=14&preset=CUSTOM&layers=B8A,B03,B02&maxcc=100&gain=0.4&gamma=1.0&time=2015-01-01|2017-06-23&cloudCorrection=none&atmFilter=&showDates=true&evalscript=) of Humboldt Glacier, shadows can be seen in the lee of the icebergs.

Using the scale and a mm rule my best guess is that the shadows are around 40m. Using the excellent suncalc website (http://www.suncalc.org/#/79.6438,-65.3247,6/2017.06.23/16:00/25/0) for that date and changing the time to match the shadows shows that the height of the iceberg is around 25m.

Assuming that the iceberg has a linear profile (i.e. it doesn't get fat underwater) then the draft of the iceberg would be around 175m.

The bathymetry map attached shows a ridge about 100m deep running parallel to Humboldt, explaining why these icebergs get stuck.

Title: Re: The Nares Strait thread
Post by: Clenchie on July 02, 2017, 04:37:25 PM
Nice works Bairgs. 8)
Title: Re: The Nares Strait thread
Post by: oren on July 02, 2017, 04:39:14 PM
Nice works Bairgs. 8)
+1
Armchair science at its finest
Title: Re: The Nares Strait thread
Post by: Shared Humanity on July 02, 2017, 05:31:28 PM
Nice works Bairgs. 8)
+1
Armchair science at its finest

Agreed.
Title: Re: The Nares Strait thread
Post by: Phil. on July 04, 2017, 01:39:45 PM
"Balanced"?  Viewing successive EOSDIS Worldview (https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2017-06-29&z=3&v=-688388.6292277403,-1165239.7638481655,-321284.62922774034,-916151.7638481656) images (from June 21), the Bell Floe has moved at least 15 km each day until yesterday (between June 28 and 29 [video below]) when one corner of it moved only a few km (northward).  With wind out of the north (per Windytv (https://www.windy.com/?80.543,-62.139,5)'s now-cast, at least), this northward movement of the floe would be due to the gyre.  Smaller floes in the area aren't moving much.  (There are a few quite small floes (bergs?) near the lower right corner of this animation that don't move, including a "" shaped one.) [Bell Floe is about 15 km wide.]
Judging by the latest Sentinel image the Bell Floe has broken up somewhat.

http://ocean.dmi.dk/arctic/images/MODIS/Kane/20170703s01b.ASAR.jpg (http://ocean.dmi.dk/arctic/images/MODIS/Kane/20170703s01b.ASAR.jpg)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 04, 2017, 02:33:00 PM
Maybe it should have been called the Liberty Bell  :'(  (although its breakage occurred on the 2nd of July, as best I can tell [edit: the Continental Congress resolved to leave GB on July 2nd; Jefferson showed the 'Declaration' to journalists on the 4th - the original 'fake news' story (http://www.electoral-vote.com/evp2017/Senate/Maps/Jul04.html#item-9)!])
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 05, 2017, 02:08:33 PM
Half the ice in Lincoln Sea has become fast ice while half is mobile, per DMI Sentinel  (http://ocean.dmi.dk/arctic/lincoln.uk.php)images (movie: July 2 & 4; still: July 4)
Title: Re: The Nares Strait thread
Post by: Phil. on July 07, 2017, 09:32:17 PM
The North end of the Nares strait is now crammed with mobile ice it'll be interesting to see how fast it moves through.
Title: Re: The Nares Strait thread
Post by: numerobis on July 13, 2017, 03:09:28 PM
From the pictures, it looks like nothing much is going through Fram. Is it melting at the top end, or is there just no pressure through the pipe?
Title: Re: The Nares Strait thread
Post by: johnm33 on July 13, 2017, 06:06:17 PM
There was a full moon on sunday, the flow usually builds for 3-4 days so I suspect it's flowing well, below the clouds. Open links and click images to expand https://seaice.uni-bremen.de/data/amsr2/asi_daygrid_swath/n6250/2017/jul/Arctic/asi-AMSR2-n6250-20170709-v5_nic.png [9th]
https://seaice.uni-bremen.de/data/amsr2/asi_daygrid_swath/n6250/2017/jul/Arctic/asi-AMSR2-n6250-20170712-v5_nic.png [12th]
Title: Re: The Nares Strait thread
Post by: Andreas T on July 13, 2017, 08:00:38 PM
the wind was blowing from the southern end of the strait until recently, strongly at times. See nullschool or these on the spot measurements from Hans island https://dataservices.sams.ac.uk/aws/ (https://dataservices.sams.ac.uk/aws/)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 17, 2017, 05:46:42 PM
The older ice in the Lincoln Sea near Greenland has not moved much in weeks (it seems), but it is now on the move, again.  This July 15-16 gif (DMI (http://ocean.dmi.dk/arctic/lincoln.uk.php) Sentinel images) shows the westward movement.  Some of this feeds Nares Strait.  (The >5km floes are still some distance from Nares.)
Title: Re: The Nares Strait thread
Post by: oren on July 18, 2017, 01:21:45 AM
Temps have been spiking recently, reaching 10oc. I find it surprising that any fast ice still remains in the fjords around the strait.
Title: Re: The Nares Strait thread
Post by: Darvince on July 23, 2017, 04:46:55 PM
That fast ice has likely been in roughly the same place for years, so I'm not surprised that it's still fastened to the shores.
Title: Re: The Nares Strait thread
Post by: Espen on July 23, 2017, 08:27:31 PM
There is no fast ice in the that area you need to go a bit further north to Hunt Fjord to find real fast ice, fast ice is a rare commodity in Greenland today and can only be found in very few places and Hunt Fjord is where you find almost all of it.
Title: Re: The Nares Strait thread
Post by: oren on July 24, 2017, 12:42:04 AM
Here is an example of fast ice in Kane Basin, attached to the Humboldt Glacier front. It has been subjected to above-zero temps for a long while, and the effects are showing - breakage, melt ponds, draining of ponds, more breakage. The high temps couldn't melt it all yet, though it's quite certain it will disappear by the time the melting season ends.
The animation runs from May 16th to July 21st, skipping 3-5 days at a time except at crucial points or where clouds prevent it. Please forgive the very crude date labels.
Title: Re: The Nares Strait thread
Post by: Espen on July 24, 2017, 09:46:36 AM
Here is an example of fast ice in Kane Basin, attached to the Humboldt Glacier front. It has been subjected to above-zero temps for a long while, and the effects are showing - breakage, melt ponds, draining of ponds, more breakage. The high temps couldn't melt it all yet, though it's quite certain it will disappear by the time the melting season ends.
The animation runs from May 16th to July 21st, skipping 3-5 days at a time except at crucial points or where clouds prevent it. Please forgive the very crude date labels.

Oren , that is not fast ice it is ordinary sea ice.
Title: Re: The Nares Strait thread
Post by: oren on July 24, 2017, 10:03:18 AM
Oren , that is not fast ice it is ordinary sea ice.
I thought that sea ice which is static by way of being attached to something is fast ice?
Title: Re: The Nares Strait thread
Post by: magnamentis on July 24, 2017, 03:49:44 PM
Here is an example of fast ice in Kane Basin, attached to the Humboldt Glacier front. It has been subjected to above-zero temps for a long while, and the effects are showing - breakage, melt ponds, draining of ponds, more breakage. The high temps couldn't melt it all yet, though it's quite certain it will disappear by the time the melting season ends.
The animation runs from May 16th to July 21st, skipping 3-5 days at a time except at crucial points or where clouds prevent it. Please forgive the very crude date labels.

Oren , that is not fast ice it is ordinary sea ice.

thanks, we never learn out, what then is the correct definition of fast ice, i thought the same like @oren
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 24, 2017, 05:23:11 PM
From the NSIDC Glossary (http://nsidc.org/cryosphere/glossary/F) referenced in our ASIF Glossary (http://forum.arctic-sea-ice.net/index.php/topic,153.msg2171.html#msg2171)
Quote
fast ice

ice that is anchored to the shore or ocean bottom, typically over shallow ocean shelves at continental margins; fast ice is defined by the fact that it does not move with the winds or currents.

[not included is a picture of fast ice]

Note: This is land fast ice. (Photo courtesy of Michael Van Woert, National Oceanic and Atmospheric Administration/Department of Commerce.)

Also, from Oxford Index (http://oxfordindex.oup.com/view/10.1093/oi/authority.20110803095811558):
Quote
Any lake, river, or sea ice that is attached to the shore (including ice shelves), grounded in shallow water, or frozen to the bottom.


[the following is additional info - "edit"...]
and from Global Cryosphere Watch (http://globalcryospherewatch.org/reference/glossary.php)'s glossary (also ASIF-recommended)
Quote
[see NSIDC definition above]
and
Quote
Sea ice which forms and remains fast along the coast, where it is attached to the shore, to an ice wall, to an ice front, between shoals or grounded icebergs. Vertical fluctuations may be observed during changes of sea-level. Fast ice may be formed in situ from sea water or by freezing of pack ice of any age to the shore, and it may extend a few metres or several hundred kilometres from the coast. Fast ice may be more than one year old and may then be prefixed with the appropriate age category (old, second-year, or multi-year).
and
Quote
Consolidated solid ice attached to the shore, to an ice wall or to an ice front. It forms by freezing to the shore of the ice cover forming in the coastal zone or as a result of freezing of drifting ice of any age category to the shore or fast ice. Vertical movement may be observed during tidal oscillations. It can be preserved without fracturing for two or more years transforming from first-year ice to multiyear ice and even shelf ice. The fast ice width can vary from several hundreds of meters to several hundreds of kilometers. That part of fast ice presenting a narrow fringe of ice directly attached to the coast with a shallow bottom and unresponsive to tidal oscillations that remains after the fast ice has moved away is called the Ice foot. Fast ice at the initial stage of formation consisting of nilas and young ice with a width up to 100-200 m is called young coastal ice. When coding and depicting fast ice on ice charts, total concentration is not indicated as this is always equal to 10/10 in accordance with the definition.
and
Quote
Sea ice that forms and remains fast along the coast, where it is attached to the shore, to an ice wall, to an ice front, between shoals or grounded icebergs. Vertical fluctuations may be observed during changes of sea level. Fast ice may be formed on site from sea water or by freezing of pack ice of any age to the shore, and it may extend a few yards (meters) or several hundred miles (kilometers) from the coast. Fast ice may be more than one year old and may then be prefixed with appropriate age category (old, second- year, or multiyear). If it is thicker than about 7 ft (2 m) above sea level, it is called an ice shelf.
and
Quote
Sea ice terminology, describing ice which forms and remains fast along the coast. It may be attached to the shore, to an ice wall, to an ice front, or between shoals or grounded icebergs. It can extend between a few metres to several hundred kilometres from the coast. It may be more than one year old, in which case it may be attached to the appropriate age category (old, second year or multi-year). If higher than 2 m above sea level, it is called an ice shelf.
and
Quote
Sea ice that is immobile due to its attachment to a coast, usually extending offshore to about the 20-m isobath. In protected bays and inlets, fast ice is smooth and level, typically reaching a thickness of between 2 and 2.5 m. Along exposed coastlines, fast ice may be greatly deformed. (Also called landfast ice.)
and
Quote
Sea ice which remains fast along the coast, where it is attached to the shore, to an ice wall, to an ice front, or over shoals, or between grounded icebergs. Fast ice may extend a few m or several hundred km from the shore. Fast ice may be more than one year old. When its surface level becomes higher than about 2 m above sea level, it is called an ice shelf.

Most definitions here and elsewhere (internet search) declare that 'fast ice' occurs only on salty (ocean/sea) water.  But this is not universal.  Some definitions ignore the first couple of meters of ice against a shore (or the equivalent). 

I guess the ice stuck fast to my windscreen (windshield) on rare winter mornings isn't actually fast ice - but hey, wind and currents don't move it!
Title: Re: The Nares Strait thread
Post by: bairgon on July 24, 2017, 06:07:55 PM
Interesting to compare that to September last year - see Worldview 10th Sept 2016 (https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2016-09-10&z=3&v=-510723.10514203674,-1118176.7314211512,-305923.10514203674,-1018720.7314211512).

It's clear that the fast sea ice breaking up in 2017 is only FYI. Also visible is the ice shelf, which is also "fast" but clearly is much older.
Title: Re: The Nares Strait thread
Post by: TerryM on July 24, 2017, 08:50:20 PM
I'm taken aback by the Oxford definition. I've always assumed that fast ice had some element of longevity inherent. Not necessarily the millennial + age of the ice shelves, but certainly not the ephemeral ice that melts away annually.


Apparently a puddle that freezes solidly during a Sunday storm is fast ice, until melted away by a Monday zephyr.


I'm liable to have difficulty adjusting to this definition.
Terry
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 24, 2017, 09:38:38 PM
See additional definitions in my post above.  None (alas) include "puddle ice", unless you consider Hudson Bay to be 'just a puddle'.
Title: Re: The Nares Strait thread
Post by: Espen on July 24, 2017, 09:54:55 PM
In some languages we have many words for snow and ice, but in others we dont!

Many word related to ice and snow originates from other languages than (Am) English.
Title: Re: The Nares Strait thread
Post by: Shared Humanity on July 24, 2017, 10:25:45 PM
While I'll occasionally have it "On the Rocks", I'll usually drink my whiskey neat.  ;)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 24, 2017, 11:08:22 PM
English tends to be a legalistic language (due to its several cultures? Hmmm), so "definitions" are sooo important.  ::) :P :o ;D and now  :-X
Title: Re: The Nares Strait thread
Post by: Phil. on July 25, 2017, 04:13:27 PM
Seems to be good flow of ice through the Nares still looking at latest Modis images.  Also the surface ice downstream of the Pietermann glacier has fractured and moved down the channel.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 25, 2017, 04:50:11 PM
Robeson Channel (northern Nares) and the southern Lincoln Sea ice flow between July 23 and 24 was northward! (DMI (http://ocean.dmi.dk/arctic/kennedy.uk.php) images)  Easy to see is a floe off the mouth of Petermann Fjord.  An interesting eddy appears to have formed southwest of the Petermann Fjord mouth.

The Kane Basin appears to have kept the surviving part of the 'Bell Floe' (red marked) for the time being.

Someone remarked how ice is melting within Nares Strait.  I believe them!

Title: Re: The Nares Strait thread
Post by: johnm33 on July 25, 2017, 09:36:09 PM
This is from the 24th to me it suggests a surge of warm water coming out of the arctic at depth, into Petermann fjord, and there being forced to the surface melting and forcing out the seasonal fast ice.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fservices.sentinel-hub.com%2Fv1%2Fwms%2Fb7b5e3ef-5a40-4e2a-9fd3-75ca2b81cb32%3FSERVICE%3DWMS%26amp%3BREQUEST%3DGetMap%26amp%3BMAXCC%3D40%26amp%3BLAYERS%3DB04%2CB03%2CB02%26amp%3BGAIN%3D0.5%26amp%3BGAMMA%3D1.0%26amp%3BCLOUDCORRECTION%3Dnone%26amp%3BEVALSOURCE%3DS2%26amp%3BWIDTH%3D1286%26amp%3BHEIGHT%3D535%26amp%3BATMFILTER%3DATMCOR%26amp%3BFORMAT%3Dimage%2Fjpeg%26amp%3BBGCOLOR%3D00000000%26amp%3BTRANSPARENT%3D1%26amp%3BNICENAME%3DSentinel%2Bimage%2Bon%2B2017-07-24.jpg%26amp%3BTIME%3D2015-01-01%2F2017-07-24%26amp%3BBBOX%3D-7909093%2C16005302%2C-6360784%2C16659603%26amp%3BPREVIEW%3D3%26amp%3BEVALSCRIPT%3DcmV0dXJuIFtCMDQqMi41LEIwMyoyLjUsQjAyKjIuNV0%253D&hash=adeb971c0bdb2149097488b872a46b3d)
Take a closer look  (http://apps.sentinel-hub.com/sentinel-playground/?lat=81.5981071957334&lng=-61.6552734375&zoom=7&preset=CUSTOM&layers=B04,B03,B02&maxcc=40&gain=0.5&gamma=1.0&time=2015-01-01|2017-07-24&cloudCorrection=none&atmFilter=ATMCOR&showDates=false)
Title: Re: The Nares Strait thread
Post by: numerobis on July 31, 2017, 05:31:06 PM
Further down the Baffin Sea, we've had southerly winds all month long. It's still continuing, as you can see by the ice motion reported by the Canadian Ice Service. That may be affecting export through Nares.

Title: Re: The Nares Strait thread
Post by: Andreas T on July 31, 2017, 07:41:44 PM
edit: moved my reply to John to the Petermann thread.
Title: Re: The Nares Strait thread
Post by: johnm33 on August 05, 2017, 01:30:46 PM
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fwww.polarview.aq%2Fimages%2F106_S1jpgsmall%2F201708%2FS1B_EW_GRDM_1SDH_20170804T122328_3535_N_1.jpg&hash=2f8ec14029a21a5abf6ecd7f084a4f27)
seems to be some sort of hold up, can it simply be the effect of the low to the north and the high in Baffin causing the current to flow north?
Title: Re: The Nares Strait thread
Post by: johnm33 on August 06, 2017, 03:44:04 PM
Still fairly clear, if this was caused by northbound currents then by now some sort of equilibrium must have been reached. With the tides peaking tomorrow I'd expect to see the strait much busier this week.
(https://gibs.earthdata.nasa.gov/image-download?TIME=2017217&extent=-916755.3212962598,-1407229.6956522674,-199955.32129625976,-721149.6956522674&epsg=3413&layers=VIIRS_SNPP_CorrectedReflectance_BandsM11-I2-I1,Reference_Features&opacities=1,1&worldfile=false&format=image/jpeg&width=700&height=670)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on August 07, 2017, 08:15:30 PM
The remains of the "Bell Floe" have apparently escaped Kane Basin under the cover of clouds between August 1 (seen) and 5 (gone, I believe).  It sure took its time (with a bell shape since at least June 17 (http://forum.arctic-sea-ice.net/index.php/topic,176.msg117326.html#msg117326), and entering Nares Strait on June 12 (http://forum.arctic-sea-ice.net/index.php/topic,176.msg116809.html#msg116809).  It got its name after this June 26 post (http://forum.arctic-sea-ice.net/index.php/topic,176.msg118599.html#msg118599) by Clenchie.)
Title: Re: The Nares Strait thread
Post by: Jim Hunt on August 13, 2017, 10:53:10 PM
Idly Googling Pen Hadow's Arctic Mission (http://greatwhitecon.info/2017/07/pen-hadows-arctic-mission-to-sail-to-the-north-pole/) I stumbled across another Arctic sailing expedition:

http://GreatWhiteCon.info/2017/07/the-northwest-passage-in-2017/#comment-222791 (http://GreatWhiteCon.info/2017/07/the-northwest-passage-in-2017/#comment-222791)

This one's called Mission Arctic, and they've recently had a gander at the Kane Basin:

Title: Re: The Nares Strait thread
Post by: johnm33 on August 15, 2017, 06:22:08 PM
Looks like Nares is icing up, must be the windchill factor. Very cold water emerging from Lincoln could be cementing the ice there?
(https://puu.sh/xaJKb/80ff723d08.jpg)
Title: Re: The Nares Strait thread
Post by: oren on August 15, 2017, 10:30:47 PM
Looks like Nares is icing up, must be the windchill factor. Very cold water emerging from Lincoln could be cementing the ice there?
I find it doubtful that open water in Nares is icing as the temperature on Hans Island in the middle of the strait is still a healthy 3oc. Wind chill cannot explain it either. The strait could be filling up due to increased export.
Quote
The effect of wind chill is to increase the rate of heat loss and reduce any warmer objects to the ambient temperature more quickly. Dry air cannot, however, reduce the temperature of these objects below the ambient temperature, no matter how great the wind velocity.
Title: Re: The Nares Strait thread
Post by: TerryM on August 15, 2017, 10:51:39 PM
Looks like Nares is icing up, must be the windchill factor. Very cold water emerging from Lincoln could be cementing the ice there?
I find it doubtful that open water in Nares is icing as the temperature on Hans Island in the middle of the strait is still a healthy 3oc. Wind chill cannot explain it either. The strait could be filling up due to increased export.
Quote
The effect of wind chill is to increase the rate of heat loss and reduce any warmer objects to the ambient temperature more quickly. Dry air cannot, however, reduce the temperature of these objects below the ambient temperature, no matter how great the wind velocity.
The bolded sounds wrong. Consider the chilling effect of dry wind on a damp surface due to phase change. ...cannot, however, reduce the temperature of these object below the Wet Bulb temperature, ... is I believe correct.
Terry
Title: Re: The Nares Strait thread
Post by: oren on August 15, 2017, 11:26:12 PM
Terry, I am at a loss, as what I copied from Wikipedia sounds about right, while what you wrote sounds about right as well...
Let me pose this as a stupid question: Can a dry above-freezing wind blowing fast enough freeze water surfaces by evaporative cooling? (My layman intuition says no)
Title: Re: The Nares Strait thread
Post by: johnm33 on August 16, 2017, 03:14:42 AM
Sublimation then? Do i believe what i see [albeit from afar] or what i know?
Title: Re: The Nares Strait thread
Post by: sidd on August 16, 2017, 04:42:47 AM
" Can a dry above-freezing wind blowing fast enough freeze water surfaces by evaporative cooling? "

In the following i assume the air temperature and humidity can be fixed (infinite heat and humidity source and sink)  and radiation is not important.

the vapor pressure of water at 0C is not zero, it is about 4 torr  (0.006 atm, 1atm is 760 torr)
so lets say you have a water surface that has a dry wind at 0.01 C blowing across it.  Water will evaporate until the temperature of the water surface reaches 0.01 C. The next bit of water coming out will try to cool the surface below 0.01 C but it will remain 0.01 C because the air will dump heat in the water through surface conduction.

lets say the air is at 0C. Then the water will give up heat thru evaporation till it reaches 0C, then give up more and freeze. then you will have an ice film at the surface. Ice has a lower vapor pressure than supercooled water, sublimation from ice is more difficult than evaporation from supercooled water below 0C.  but the ice film at the surface will not cool more than 0C since the air above will keep it there.

lets say the air temp is lowere to -0.01C. Then a sublimation will cool the ice to -0.01C but no more, since the air-ice interface will conduct heat out of the air to maintain temperature.

sidd
Title: Re: The Nares Strait thread
Post by: TerryM on August 16, 2017, 06:59:20 AM
A simpler way to think about the original quote might be to remember how wet bulb temperature was originally recorded.


Two identical thermometers are tied together on a one meter long string. One thermometer's bulb is lightly wrapped in wet cotton, then the device is swung around ones head for ~30 seconds.
The dry thermometer gives dry bulb temperature and the bulb wrapped with wet cotton provides wet bulb temperature.


The delta between the two temperatures is lower the dryer the air is, therefor dry air blowing across a wet surface will lower the temperature to the wet bulb temperature, but no further.


Terry


Terry
Title: Re: The Nares Strait thread
Post by: oren on August 16, 2017, 07:15:34 AM
Thanks for the almost-OT but very enlightening discussion. Looking at the data on Hand Island, using 75% humidity and 987 mbars, a 3oc reading become 1.4oc wet-bulb temp. In addition, the wind speed is around 5 m/s so it's nothing dramatic. So perhaps Hans Island is not representative of the whole strait, but I don't think there is any surface freezing going on. The mystery remains what IS shown on the sat image.
Title: Re: The Nares Strait thread
Post by: johnm33 on August 16, 2017, 11:20:01 AM
Thanks all, the sea emerges from Lincoln at about -1.2C, the air flows from high at about -20C, so presumably dry, more like -5C at sea level, and warms going north. Still at -1C over Lincon and i assume still quite dry, so freezing any melt water there, cementing the otherwise weak looking ice in place blocking export. So just a skin of ice disturbed by currents?
https://earth.nullschool.net/#2017/08/15/0600Z/wind/surface/level/overlay=temp/orthographic=-47.32,79.43,3000/loc=-61.839,81.900
Title: Re: The Nares Strait thread
Post by: johnm33 on August 18, 2017, 11:19:03 PM
At last there's some movement, too late to save my low guesses in the polls, but good we dodged the bullet.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fservices.sentinel-hub.com%2Fv1%2Fwms%2Fb7b5e3ef-5a40-4e2a-9fd3-75ca2b81cb32%3FSERVICE%3DWMS%26amp%3BREQUEST%3DGetMap%26amp%3BMAXCC%3D100%26amp%3BLAYERS%3DB8A%2CB03%2CB02%26amp%3BGAIN%3D0.4%26amp%3BGAMMA%3D1.0%26amp%3BCLOUDCORRECTION%3Dnone%26amp%3BEVALSOURCE%3DS2%26amp%3BWIDTH%3D1286%26amp%3BHEIGHT%3D535%26amp%3BATMFILTER%3DATMCOR%26amp%3BFORMAT%3Dimage%2Fjpeg%26amp%3BBGCOLOR%3D00000000%26amp%3BTRANSPARENT%3D1%26amp%3BNICENAME%3DSentinel%2Bimage%2Bon%2B2017-08-18.jpg%26amp%3BTIME%3D2015-01-01%2F2017-08-18%26amp%3BBBOX%3D-7690177%2C16396659%2C-6141869%2C17050960%26amp%3BPREVIEW%3D3&hash=6b627035ebbbe7c500d2c0fb7aae160f)
Title: Re: The Nares Strait thread
Post by: numerobis on August 23, 2017, 04:59:11 PM
CIS doesn't analyze very far up the straits, but the outflow of Nares has been moving fairly fast the past couple days, 10 - 15 miles a day (around 1 km/h).
Title: Re: The Nares Strait thread
Post by: Thomas Barlow on September 19, 2017, 03:20:31 PM
Do you think the Nares will freeze this winter?
Title: Re: The Nares Strait thread
Post by: Shared Humanity on September 19, 2017, 04:06:42 PM
Do you think the Nares will freeze this winter?

Yes.
Title: Re: The Nares Strait thread
Post by: Thomas Barlow on September 19, 2017, 10:10:43 PM
Do you think the Nares will freeze this winter?

Yes.
Rationale please?
Since it didn't freeze last winter.
https://media.giphy.com/media/l378aPcRIiXYF3S5W/giphy.gif
Title: Re: The Nares Strait thread
Post by: Shared Humanity on September 20, 2017, 08:05:18 PM
I certainly do not have any solid scientific rationale for expecting a freeze. It is just that the Nares freezes over more often than not and this causes me to think that it is more likely to freeze this year.

Nares did not freeze last year because the more southern ice arch did not form, blocking transport of ice. Last freeze season was remarkably warm. I suppose if we have a repeat of this ridiculously warm winter, it may happen again.
Title: Re: The Nares Strait thread
Post by: Thomas Barlow on October 06, 2017, 04:32:35 AM
I suppose if we have a repeat of this ridiculously warm winter, it may happen again.
It is off to a horrendously bad start - see below. Add to that, the latest assessments are that globally, September shattered records.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on November 07, 2017, 07:11:09 PM
Still flowing.  Poorly colorized floes in DMI Sentinel (http://ocean.dmi.dk/arctic/kane.uk.php) images - Nov 5 and 6 - showing Kane Basin.  I tried to create a GIF, but it didn't work.
Title: Re: The Nares Strait thread
Post by: Brigantine on November 08, 2017, 12:42:49 AM
Interesting. The red one seems to be right on the margin of the fast ice? It rotated slightly, but many features around it are static.
Title: Re: The Nares Strait thread
Post by: Phil. on November 10, 2017, 02:43:14 PM
As I recall from the summer the region where the red one is was an eddy.  We had a floe that everyone was interested in which travelled very rapidly until it reached there then got held up for quite a long time.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on November 20, 2017, 03:22:35 PM
I'm occasionally watching ice get exported out through Nares Strait via DMI's Sentinel imagery (http://ocean.dmi.dk/arctic/kane.uk.php).  Here is yesterday's Kane Basin image showing ice flowing in the channel on the northwest side of the basin.  A large piece of the fast ice appears to be peeling off on the south end of the basin
Title: Re: The Nares Strait thread
Post by: Niall Dollard on November 26, 2017, 06:10:18 PM
Here is the Kane Basin for the 24th to 26th Nov. There is a blockage now just below 79 N.

There is a large block of what looks like multiyear ice (circled magenta) that hasn't moved much and has drifted back slightly north between 25th and 26th.

Title: Re: The Nares Strait thread
Post by: Brigantine on November 26, 2017, 09:10:30 PM
So the southerly winds in Baffin Bay are having an impact.

How long would it need to stall like that to have a chance to freeze fast? (and stay fast after the wind changes).
I imagine it would take a lot. Even under colder conditions.
Title: Re: The Nares Strait thread
Post by: oren on November 27, 2017, 12:44:00 AM
Normally the strait gets "stuck" and arches form at the narrow points (Kane Basin exit and Lincoln Sea entrance) in January/February.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on November 30, 2017, 07:09:17 PM
Crosspost (abbreviated)
Here is a sea ice thickness product for 27 Sep to 30 Nov plus 9 day forecast taken from the Mercator Ocean site.
...
Export out the Nares Strait is quite effective.

It is more convenient in some ways to view animations at the MercOcean site, for example salinity x depth from May-Nov are linked below though there's no practical way to capture these or rescale (other than full screen mode). They do work well as previews however. The forecast salinity for Dec 9th shows the freshening in the Beaufort Gyre to 318 m depth (but not beyond) as well as the Atlantic Water salt finger wrapping along the Svalbard/Siberian shelf.

MercOcean uses a javascript library called Leaflet which works ok overall but has various limitations and bugs. The server is quite fast. The site may be fairly new as most of the cross sections are not yet available.

http://bulletin.mercator-ocean.fr/en/permalink/PSY4/animation/3/20170501/20171130/2/1
http://bulletin.mercator-ocean.fr/en/permalink/PSY4/animation/3/20170501/20171130/2/2
http://bulletin.mercator-ocean.fr/en/permalink/PSY4/animation/3/20170501/20171130/2/3
http://bulletin.mercator-ocean.fr/en/permalink/PSY4/animation/3/20170501/20171130/2/4
Go to A-Team's post to see the images...
Title: Re: The Nares Strait thread
Post by: A-Team on December 01, 2017, 07:33:01 AM
I'm  really surprised by what this is showing passing through the Nares, don't really see how it could be an artifact of Mercator Ocean ice thickness series. The CAA also has actively flowing floes. Both are in the lower left.

There's a way to cross-post images and animations already uploaded to another forum: paste the url, select it, and hit the second button in the second row next to the flash icon. This inserts the image within the text, rather than putting on the bottom. There seems to be no limit to how many images can be inserted whereas it's been set to four for new uploads.

May be able to do more of this area at a better scale  by re-orienting into 'Greenland down' position ... also adding a couple of sea ice concentration views from UH AMSR2 colored so as to facilitate motion visualization. All four animations have the same date range, 27 Sep to 30 Nov 2017.

(https://forum.arctic-sea-ice.net/index.php?action=dlattach;topic=2141.0;attach=55504;image)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 02, 2018, 04:12:59 AM
Cross post
Lincoln Sea and Nares Straight -Jan 1
(https://forum.arctic-sea-ice.net/index.php?action=dlattach;topic=2141.0;attach=56503;image)
Title: Re: The Nares Strait thread
Post by: A-Team on January 02, 2018, 05:29:23 PM
Check out this one: unbelievable break-up and Nares export of the very thickest Lincoln Sea ice, late May/early June of 2017. Sentinel-1AB has the advantage of seeing through clouds. The massive processing of these files was provided by R Saldo at DTU.

I'm hoping that Neven can tweak the blog software admin settings for attachments to get rid of long-gone 'mpg' and allow 'mpg4' so these could display like youtubes on the forums. The link and image are to the lowest resolution version of this file.

Making a gif generates a couple thousand frames and a file size of 78 MB, too large for the forum. Only cropped+down highlights of the animation are shown below.

http://www.seaice.dk/movies/S1AB-LincolnSea-JanSep17/LincolnSea-JanSep17-450-h264.mp4
Title: Re: The Nares Strait thread
Post by: Neven on January 02, 2018, 06:30:46 PM
I'm hoping that Neven can tweak the blog software admin settings for attachments to get rid of long-gone 'mpg' and allow 'mpg4' so these could display like youtubes on the forums. The link and image are to the lowest resolution version of this file.

Turns out I could check a box for 'Local MP4' in the Simple Audio Video Embedder settings. Seems to work.
Title: Re: The Nares Strait thread
Post by: A-Team on January 02, 2018, 06:54:39 PM
Thx, that works great! (Not real sure why, it does not change the 'allowed file types' of attachments but it may be similar to allowing youtubes.) This mp4 format is popular in climate-change journals whereas gif is rarely seen. It has more favorable compression, allowing smaller file sizes. Also having a controller is much more convenient than with gifs. Believe twitter also uses this under the hood too.

After installing the 'SaveAsMovie' plugin into Fiji/ImageJ, a 48 MB gif consisting of a full year of daily Ascat files reduced to an astonishing 1.4 MB. (However that's just on my computer so unless photobucket etc are used to provide a url, it can't be uploaded to the forum!)

Quote
Allowed file types: gif, jpg, mpg, pdf, png, txt, jpeg
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 02, 2018, 07:09:25 PM
... Nares export of the very thickest Lincoln Sea ice, late May/early June of 2017 ...
I'm delighted to see this animation, A-Team.  I knew 'at the time' that it was all mobilized.  Your gif (or whatever file type it is) shows that about half was actually exported. 

Like so much multi-year ice (MYI) across the Arctic, the remaining thick ice is highly fractured with interstitial first year ice (FYI).  Few, if any, of the remaining Lincoln Sea MYI hunks (separate floes last summer, but now 'welded' together with FYI) are large enough to form an ice bridge by themselves, should they continue to approach Nares Strait.  (Most of what is transported into Nares Strait is ice that formed west or northwest of the Lincoln Sea, and is less coherent than, and surely thinner than, the northeast Lincoln Sea ice that appears whiter than other ice in the gif.)
Title: Re: The Nares Strait thread
Post by: A-Team on January 02, 2018, 09:26:04 PM
The higher resolution versions load but only in miniature so need to be opened in new tabs which are slow to play so visit the site itself to view at better resolution (95 MB, 273 MB). These run from 01 Jan 17 to 25 Sep 17.

It's not clear why different swaths and even the same swath on different dates vary in contrast but clouds, water vapor, fog, salinity, ice roughness, ice melt ponds, and residual daylight may have small effects on the consistency of what Sentinel-1AB sees.

http://www.seaice.dk/movies/S1AB-LincolnSea-JanSep17/
Title: Re: The Nares Strait thread
Post by: A-Team on January 02, 2018, 11:43:30 PM
Quote
gif shows about half [or the NE Lincoln Sea MYI was actually exported.
Good eye! Blue to pink area ratio below is 46%.

So did Piomas catch the massive loss of half the very thickest ice in the entire Northern Hemisphere? No, it's oblivious to events like this because 20m Sentinel is not used to reset accruing model errors, only daily ice concentration data which gets the ice edge outline right but doesn't see internal ice motion very well nor this Lincoln Sea ice breakup and Nares export.

Quote
the remaining thick ice is highly fractured with interstitial first year ice
That point is made forcefully in the new sea ice age paper: it does not work to assign large footprint pixels to a single ice age, better to use color to represent the proportions of each ice age class.

A new tracking algorithm for sea ice age distribution estimation
AA Korosov et al
https://www.the-cryosphere-discuss.net/tc-2017-250/tc-2017-250.pdf
(https://forum.arctic-sea-ice.net/index.php?action=dlattach;topic=119.0;attach=47648;image)
Title: Re: The Nares Strait thread
Post by: Neven on January 03, 2018, 09:04:55 AM
Thx, that works great! (Not real sure why, it does not change the 'allowed file types' of attachments but it may be similar to allowing youtubes.) This mp4 format is popular in climate-change journals whereas gif is rarely seen. It has more favorable compression, allowing smaller file sizes. Also having a controller is much more convenient than with gifs. Believe twitter also uses this under the hood too.

After installing the 'SaveAsMovie' plugin into Fiji/ImageJ, a 48 MB gif consisting of a full year of daily Ascat files reduced to an astonishing 1.4 MB. (However that's just on my computer so unless photobucket etc are used to provide a url, it can't be uploaded to the forum!)

Quote
Allowed file types: gif, jpg, mpg, pdf, png, txt, jpeg
Title: Re: The Nares Strait thread
Post by: A-Team on January 03, 2018, 09:22:56 AM
Quote
Allowed file types: gif, jpg, mpg, pdf, png, txt, jpeg, mp4
Awright!

But weirdly, it is accepting the attachment upload but not displaying it the way it would accept and display a gif, jpg, or png. Unclear why it will display an external link to a mp4 but not an internal link. (txt makes no sense to display because it could just be entered in the text box.) mpg ... not seen that file format in a while, not sure what happens there.

Upon clicking, the attached mp4 (of a full year of Ascat ice movement) does not display in a new browser tab but instead downloads to your hard drive. There upon clicking, it will display in QuickTime etc. So not ideal for group discussion sharing.

I am trying the converter: https://convertio.co/mp4-converter/

"Dec 20, 2017 - The only reason a file is ever given the "mpg" extension is because older file systems and operating systems are restricted to 8.3 file names- that is, 8 letters, a period, and a three letter extension... In this case, MPG mostly uses file converted from VHS tape or VCD players. On the other hand MP4 is latest and widely use video format around the world. MP4 uses MPEG-4 compression which is the advanced / updated form of MPEG-1 compression technique."

Now I am trying long forgotten dropbox, photobucket, mediafire and gdrive accounts; while the first works as a link, it doesn't display here as mp4:

https://www.dropbox.com/h
https://drive.google.com/open?id=1_aJBIA_Hv7bWRs2EF5KQevhN4nLPY4Na
http://www.mediafire.com/file/zpd5qi51hjtc9n7/2017-ascat-year.mpg

Title: Re: The Nares Strait thread
Post by: oren on January 03, 2018, 09:51:29 AM
A-Team, thank you for that wonderful Lincoln breakup animation. I remember that spectacular event vividly.
Title: Re: The Nares Strait thread
Post by: Neven on January 03, 2018, 11:45:16 AM
Something went wrong with my last comment (should've been posted yesterday, and this morning I got some error), but anyway.

Yeah, I could check a 'local mp4' box in the settings of the 'Simple Video Audio Converter' package for SMF forums, so that links to mp4 files can be played like YouTube links. I've also added mp4 to allowed attachments, but these don't seem to play automatically. I'll see if I can fix that, but even if I can, I fear that mp4 attachments may take up too much space on the server. I don't know what the data limits/costs are.
Title: Re: The Nares Strait thread
Post by: Neven on January 03, 2018, 01:11:11 PM
I've installed a mod called 'Play Media Attachment'.

Test...


Edit: In Chrome only the bar with the play button appears, nothing happens when pressed. In Firefox there's a window, but pressing play results in "No video with supported format and MIME type found".

Edit2: I'll try and solve this later today. BTW, it is now also possible to send other members attachments through PM, because it says here (https://custom.simplemachines.org/mods/index.php?action=parse) that installation of 'Play Media Attachment' should be preceded by installation of this mod (http://custom.simplemachines.org/mods/index.php?mod=1974) called 'PM Attachments'. And so that's what I did.
Title: Re: The Nares Strait thread
Post by: Mozi on January 03, 2018, 04:31:35 PM
Hi Neven, the reason that is not playing here is because the video link is for an http:// address and this forums runs on https://, and Chrome and other browsers don't like including insecure content in a secure webpage. I'm afraid there isn't a simple solution for this other than hosting the video on an https:// address (or users can adjust their browser configuration, though this is probably a bad idea in general.)
Title: Re: The Nares Strait thread
Post by: lurkalot on January 03, 2018, 05:25:36 PM
The play button works perfectly for me in Chrome, Neven.
Title: Re: The Nares Strait thread
Post by: Neven on January 03, 2018, 06:44:09 PM
The play button works perfectly for me in Chrome, Neven.

Thanks for the feedback. To be clear: Is that the play button in my previous comment (two comments above yours)?
Title: Re: The Nares Strait thread
Post by: lurkalot on January 03, 2018, 07:53:19 PM
Yes
Title: Re: The Nares Strait thread
Post by: Neven on January 04, 2018, 02:17:25 PM
Tor Bejnar posted a mp4 as attachment in another thread (https://forum.arctic-sea-ice.net/index.php?topic=103.new;topicseen#new), and it worked for me there, both in Chrome and FF. That's encouraging.

Knock yourself our, A-Team, but please, no huge files.  ;)
Title: Re: The Nares Strait thread
Post by: A-Team on January 05, 2018, 03:01:49 PM
Quote
no huge files
The mp4 works some major magic through different compression that exploits visual illusions, reducing a 48 MB gif to a 1.8 MB mp4. So in theory could run the Ascat for 5 consecutive years and still stay within bounds. However other things break as the number of individual frames gets too large.

It is all playing fine in the Opera browser (which I use because of its totally effective code level ad blocker).
Title: Re: The Nares Strait thread
Post by: A-Team on January 07, 2018, 03:55:30 PM
Now the question is, what got changed to cause our usual gif animations not to play? Below is a tiny 3-frame animation intended show what ice ages are being exported out the Nares. This is animating normally so let's try a larger one but still well within the 700x700 pixel and file size constraints. It is not animating without a click which somewhat localizes the admin settings problem. A half-size also does not animate but a quarter size does. Weird!
Title: Re: The Nares Strait thread
Post by: Neven on January 07, 2018, 04:55:29 PM
I'll try and have a look what the thresholds for gif animations are, but I fear it may be in code somewhere, and I lack skills in that department.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on January 25, 2018, 04:50:45 PM
cross post (and copied GIF):
Lincoln Sea Nares Export from 2017-12-24 to 2018-1-24. One tracked section of ice traveled approximately 115 miles (185km) in 31 days.  Furthest travel in one day was approximately 12 miles (19.3km).
Thank you, Ice Shields!
Note that the last 5 or 8 frames show mobilization of the north-of-Greenland ice.  This includes the remaining 'half' of thickest ice in the Lincoln Sea environs written about above.
Title: Re: The Nares Strait thread
Post by: A-Team on February 02, 2018, 12:21:37 PM
Quote
Note that the last frames show mobilization of the north-of-Greenland ice the remaining 'half' of thickest ice in the Lincoln Sea environs
I'm also thinking that Lincoln Sea ice has two really distinct areas (despite often being described as the stagnant oldest thickest ice in the Arctic). The western part (on the 'left') turns over very rapidly as the caving-in arc recedes; the ice there at any given moment may be old and thick but it hasn't been in residence for even half a year, it moved over from the CAA or down from central.

The second portion of the Lincoln Sea ice to the east (on the 'right') has found a very quiet spot  hugging the western corner of Morris Jesup. It is neither caught up in the oceanic current exiting the Nares nor in shear lines of a large scale rotating icepack (like we'll see from this super-storm on Tuesday).

However Ascat too is now showing the second half of this quiescent ice heading to collapse and exiting the Nares. The three versions show developments since the 15 Sep 2018 minimum. The spots that serve as movement trackers do not have any obvious counterpart in NOAA or Sentinel-1AB and may just be rough or smooth areas rather than floes or lead features.

The second mp4 compares the ice movement action along the whole CAA strip from Banks Island to the Fram for the last 8 years. It is slightly stretched (distorted) in the vertical direction to expand the key narrow area along the CAA.

Technical note: conversion of a gif to mp4 seems to work better if the size is kept at 680x680 or below (because movies aim for 720 pixel standard width, which rescales the 700 pixel forum width down to 680.) Another workaround would be adding a blank gray edge 20 pixels wide to the right of 700 pixel wide content. In ImageJ, saving at the default 7.0 frame rate in the .mov container using RAW codec at high video quality, followed by online conversion to mp4 at https://www.online-convert.com/, gives a forum-acceptable outcome.

The mp4 forum viewer has a popup menu that can loop the movie and hide the floating control bar .
Title: Re: The Nares Strait thread
Post by: oren on February 02, 2018, 01:38:45 PM
Thanks for these wonderful animations A-Team.
If I recall correctly there was another such movement of the protected ice off the North of Greenland towards Nares in spring or summer 2017, but then most of it stopped before it got there and moved back a bit. This time it seems the motion has continued in at least three big "waves", each one more damaging than the last as the cumulative motion is what counts. And I can't really see a Lincoln "arch" forming anytime soon with this kind of mobility.
Title: Re: The Nares Strait thread
Post by: A-Team on February 02, 2018, 03:38:35 PM
Quote
Lincoln sea protected ice motion has continued in three big "waves", each one more damaging than the last...can't really see a Lincoln "arch" forming with this kind of mobility.
The last two days have been stable with only floes already broken off the arc moving. A large crack in the floating glacier ice shelf appeared somewhere between the 11th and 18th of January but has not developed further (arrow).

Winds from this impending storm may blow Lincoln Sea ice to the northeast though the overall effect on the ice pack is hard to anticipate. Winds, even from extreme low pressure systems, depend on the distance to the nearest high pressure zones and a steep gradient between them.

The slides below show nullschool GFS winds forecast three days out over yesterday's Ascat ice. A couple of days of strong consistent winds from the Barents/Kara will push the ice towards the Alaskan coast and out the Bering Strait; the cyclonic rotation applies stronger torques with distance from the drifting low pressure center (of 551 hPa!) which will cause massive radial shears of the ice pack but not so much new leads.
Title: Re: The Nares Strait thread
Post by: oren on February 02, 2018, 04:49:20 PM
The last two days have been stable with only floes already broken off the arc moving. A large crack in the floating glacier ice shelf appeared somewhere between the 11th and 18th of January but has not developed further (arrow).
Thanks. I believe this arc is too wide to be able to hold, but that's just a hunch.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on February 02, 2018, 06:36:45 PM
Monday's forecast winds (per Windy.tv (https://www.windytv.com/?gust,83.148,-52.295,5,m:fWJaeyy)) in the Lincoln Sea are for 60+ kt wind gusts most of Monday and 50+ kt gusts the first half of Tuesday.
Title: Re: The Nares Strait thread
Post by: romett1 on February 02, 2018, 10:09:33 PM
Monday's forecast winds (per Windy.tv (https://www.windytv.com/?gust,83.148,-52.295,5,m:fWJaeyy)) in the Lincoln Sea are for 60+ kt wind gusts most of Monday and 50+ kt gusts the first half of Tuesday.

Last three days (Jan 31 - Feb 02). Would be interesting to see "after wind gusts" image. Images: http://ocean.dmi.dk/arctic/lincoln.uk.php
Title: Re: The Nares Strait thread
Post by: romett1 on February 03, 2018, 09:27:33 PM
Last 4 days - I thought it will be calm before storm, but lot of action already today. Images: http://ocean.dmi.dk/arctic/lincoln.uk.php

Title: Re: The Nares Strait thread
Post by: gerontocrat on February 03, 2018, 09:32:50 PM
Helluva a big plug-hole.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on February 04, 2018, 06:34:23 AM
Further to my 2/2/18 post (above), today's windy.tv (https://www.windytv.com/?gust,82.288,-45.044,5,m:fWCaexf) shows 50+ kt wind gusts on Monday and 40+ kt wind gusts on Tuesday. (basically, 10 mph less) [I know, knots are nautical miles per hour and mph are statute miles per hour.]
Title: Re: The Nares Strait thread
Post by: be cause on March 02, 2018, 10:22:40 PM
Sentinel shows a temporary arch at 79'N in Kane .. as everything N and S is still in motion I doubt the arch will last . I guess current is driving current momentum ? b.c.
Title: Re: The Nares Strait thread
Post by: Niall Dollard on March 15, 2018, 12:38:25 AM
Looking at recent Worldview images, it seems there is an ongoing attempt at making a new arch south of the original arch that formed March 1st.

I cannot see this as clearly though on the sentinel images (but I haven't seen the March 14 image yet).
Title: Re: The Nares Strait thread
Post by: Niall Dollard on March 15, 2018, 08:03:29 PM
Yes the sentinel images confirm that a new arch has formed below the first arch.

Title: Re: The Nares Strait thread
Post by: Niall Dollard on March 21, 2018, 10:15:35 PM
A close up of the lower (2nd arch) that formed circa March 13th. From Sentinel Playground. Image acquired March 20th.
Title: Re: The Nares Strait thread
Post by: Niall Dollard on March 23, 2018, 03:10:35 PM
A big chunk has broken off the lower arch on the 22nd March.
Title: Re: The Nares Strait thread
Post by: FrostKing70 on March 23, 2018, 06:25:46 PM
The animation makes curious.  There appears to be a straight line on the NW side of the water area, whereas the north east and east south sides show a jagged pattern.   What is the theory of the straight line?
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on March 23, 2018, 08:21:42 PM
The water current in Kane Basin and Smith Sound is stronger on the Canadian side.  (On the Greenland side, there is some north-bound current).  I think, therefore, water (and abrasive ice chunks) scour the west side of Nares Strait.  The fast ice on the 'chunky' north and east sides breaks where it may, often between and around frozen-in floes, and nothing challenges its ruggedness.
Title: Re: The Nares Strait thread
Post by: Niall Dollard on March 23, 2018, 08:43:47 PM
And in addition to what Tor has just said, the fast ice on the Canadian side gets some much needed shelter in the lee of the two promontories (marked). Bearing in mind that the current is moving NE to SW on that side. Moving quite fast too. Look at today's image and see how far the chunk has moved down the strait.

The original arch to the north is visible too in this image.
Title: Re: The Nares Strait thread
Post by: Niall Dollard on March 27, 2018, 03:01:48 PM
After 21 March, there has been very little movement at all right up through the Nares Strait north of the arch and in the Lincoln Sea.

The attached GIF of the Lincoln Sea runs through from March 21 to March 26.
Title: Re: The Nares Strait thread
Post by: Adam Ash on April 05, 2018, 02:59:36 AM
Arctic sea ice becoming a spring hazard for North Atlantic ships
http://environmentalresearchweb.org/cws/article/yournews/71370 (http://environmentalresearchweb.org/cws/article/yournews/71370)

Suggests that the arches in Nares and the Garlic Press are not holding over the winter.
Title: Re: The Nares Strait thread
Post by: Niall Dollard on June 06, 2018, 01:20:06 AM

In general I think it is important for posterity to cross-post the animations and images in this thread to the general Nares thread, which can later serve as an excellent historical resource.

I agree. I had posted two animations in the other poll-type-Nares threads and am posting them now here for posterity.

One of the arch formation on 1st to 4th March 2018

The other is of the crack forming in the Kane Basin (northern part) 2nd -4th June 2018
Title: Re: The Nares Strait thread
Post by: Clenchie on June 11, 2018, 10:09:18 PM
Not sure if it is significant but just noticed a gap in the ice opened up at the North end.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 12, 2018, 02:01:51 AM
Windytv (https://www.windy.com/81.505/-63.237?81.292,-63.237,5) has been forecasting winds out of the south for several days (at least), so I am not surprised by the arch holding in the southern Kane basin while ice breaks up all along the upper parts of the strait.
Title: Re: The Nares Strait thread
Post by: oren on June 12, 2018, 03:01:58 AM
Not sure if it is significant but just noticed a gap in the ice opened up at the North end.
Interesting. Note the gap opened due to ice transport. It's a combination of two things - breakage of the ice in the Lincoln Sea, and reversal of the prevailing wind. Typically the wind in the strait goes from northeast to southwest, along with the almost-constant water flow. But currently it is blowing from southwest to northeast, as shown on WindyTV.
Title: Re: The Nares Strait thread
Post by: uniquorn on June 14, 2018, 01:41:08 PM
A little wear and tear, but holding yesterday.
Polarview S1 Jun13
Title: Re: The Nares Strait thread
Post by: oren on June 16, 2018, 08:43:18 PM
A very clear image of Kane Basin. The arch is still holding nicely, with the original arch very visible behind. Melt-water on the fast ice around the basin gives a clue about the weather. Hans Island weather station (https://dataservices.sams.ac.uk/aws/) (in Kennedy channel north of the Basin) gives another clue.
Normally the arch should go in a couple of weeks, though it seems rather stable. We'll know when the time comes.
Title: Re: The Nares Strait thread
Post by: uniquorn on June 18, 2018, 10:25:19 PM
Since it is nearly 21st(my guess), here is a worldview animation from may 29-jun18.
Title: Re: The Nares Strait thread
Post by: oren on June 25, 2018, 03:43:41 AM
Another animation, up to June 24th. The "new" arch is being eaten slowly but the end is not yet in sight. I do notice that a support of the original arch broke on the northwest side. It could yet go within the month though a first half of July finish is more probable.
Title: Re: The Nares Strait thread
Post by: johnm33 on June 26, 2018, 10:04:37 AM
Looks like a powerful current is flowing south
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpuu.sh%2FAM8I2%2F14dd6c4373.jpg&hash=59715cee416228d624f8909866b4a437)
 from (http://bslmagb.nerc-bas.ac.uk/iwsviewer/?image=DataPolarview/111_S1jpeg2000_201806/S1B_EW_GRDM_1SDH_20180625T211338_BD7C_N_1.8bit.jp2)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 26, 2018, 06:57:42 PM
Cracks are approaching the arch...
(Image from: DMI Sentinel  (http://ocean.dmi.dk/arctic/kane.uk.php)from today)
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 26, 2018, 08:02:59 PM
I find it amazing how open part of Nares Strait is, given the blockage in Kane Basin.  Snagged from yesterday's Worldview image (https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2018-06-25-T00%3A00%3A00Z&z=3&v=-528197.8083292734,-1040383.9999999992,-178501.80832927336,-800255.9999999992).
Title: Re: The Nares Strait thread
Post by: oren on June 26, 2018, 10:56:25 PM
I think it's often like that at this time of year, though not sure of the exact mechanism.
Maybe the strong southbound current increases bottom melt beyond normal rates, and together with air temps above zero causes the thinnest ice to disappear, and then the current sweeps the thicker ice south leaving a polynia in the northern part.
Title: Re: The Nares Strait thread
Post by: Shared Humanity on June 27, 2018, 05:50:16 AM
I think it's often like that at this time of year, though not sure of the exact mechanism.
Maybe the strong southbound current increases bottom melt beyond normal rates, and together with air temps above zero causes the thinnest ice to disappear, and then the current sweeps the thicker ice south leaving a polynia in the northern part.

This makes sense.
Title: Re: The Nares Strait thread
Post by: uniquorn on June 27, 2018, 09:23:25 PM
The north west side does look weaker. Windy ecmwf forecast temperatures above zero for the next two days with up to 60km/h gusts.
Worldview jun27 terra/modis true color and bands 7,2,1
Title: Re: The Nares Strait thread
Post by: oren on June 27, 2018, 11:31:48 PM
For actual and detailed weather measurements in the strait itself, there's my favorite weather station on Hans Island, a bit to the north in the Kennedy Channel.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fwww.journal.forces.gc.ca%2Fvol13%2Fno3%2Fimages%2F34-KRISTIANSEN-image02-eng.jpg&hash=cb7e95969d3077570983c6ee414406ea)

Arctic Weather Station :: Hans Island (https://dataservices.sams.ac.uk/aws/)

In the last 48 hours temps have indeed been above zero more often than not.
Title: Re: The Nares Strait thread
Post by: uniquorn on June 28, 2018, 01:10:00 AM
thanks Oren. Will see how windy does against aws:hans island
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on June 29, 2018, 08:13:28 PM
The beginning of the end of the Kane Basin bridge.  DMI's Sentinel-1 today (http://ocean.dmi.dk/arctic/kane.uk.php)
Title: Re: The Nares Strait thread
Post by: Clenchie on June 29, 2018, 08:50:34 PM
The beginning of the end of the Kane Basin bridge.  DMI's Sentinel-1 today (http://ocean.dmi.dk/arctic/kane.uk.php)

Yes, judging by the cracks it looks like the ice is about to disintegrate all the way up to the top of the channel.
Title: Re: The Nares Strait thread
Post by: bairgon on June 29, 2018, 11:55:21 PM
The Lincoln sea ice is already funnelling into the gap left further up the channel. With the collapse of the arch this should continue.

Click to animate.
Title: Re: The Nares Strait thread
Post by: Jim Hunt on June 30, 2018, 12:34:06 PM
The Lincoln sea ice is already funnelling into the gap left further up the channel.

Yesterday's static view from Terra of both ends of the Nares Strait:

http://GreatWhiteCon.info/resources/arctic-sea-ice-images/summer-2018-images/#Nares
Title: Re: The Nares Strait thread
Post by: Shared Humanity on June 30, 2018, 05:27:46 PM
In that last image the angle of those cracks suggest that the entire mass of ice in the strait has slipped slightly towards the open water. And with the prevalent bluing throughout the image, there is a whole lot of melt going on. Would not be surprised if it gives way soon and, when it does, the disintegration will be quick as all of those tiny flows will break free from each other.
Title: Re: The Nares Strait thread
Post by: wallen on July 01, 2018, 02:50:11 AM
Nares Strait looks distinctly like a champange bottle in the process of popping, with the build up of pressure from behind and I think when it does, it will quite spectacularly.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 01, 2018, 05:37:28 AM
I believe this PolarView (https://www.polarview.aq/arctic) image dated 2018-06-30 T 12:25:22.35 shows a crack to the face of the ice bridge in the central but 'southern' part of this screen print, along with a little movement. The crack runs mostly along the coast upstream of where it heads to the ice arch edge. image URL (http://bslmagb.nerc-bas.ac.uk/iwsviewer/?image=DataPolarview/111_S1jpeg2000_201806/S1A_EW_GRDM_1SDH_20180630T122522_35AB_N_1.8bit.jp2)
Title: Re: The Nares Strait thread
Post by: Espen on July 01, 2018, 10:03:53 PM
The southern arch at Nares is now broken:
Title: Re: The Nares Strait thread
Post by: FishOutofWater on July 01, 2018, 11:55:47 PM
The photo taken on 30 July June shows the arch had already broken. Today the wind shifted to northerly, driving the mass of ice southwards.
Title: Re: The Nares Strait thread
Post by: magnamentis on July 02, 2018, 12:20:43 AM
The photo taken on 30 July shows the arch had already broken. Today the wind shifted to northerly, driving the mass of ice southwards.

June ?
Title: Re: The Nares Strait thread
Post by: Alexander555 on July 02, 2018, 07:35:10 PM
Maybe this will create some more ice to flush trough the Nares Strait.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 06, 2018, 05:18:28 AM
In the good old days, we could watch many distinctive floes enter the north end of Nares Strait and watch them exit Smith Sound 5 or 30 days later, somewhat beaten, perhaps, but readily trackable.  This year, it nearly all looks like garbage, at both ends and in the middle.  I believe it was last year that took 'forever' to see an identifiable floe go the length - so much melted or got pulverized along the way (and it wasn't in a hurry to go south).  I wouldn't dare start a poll this year as very few hunks of ice look like they might make it all the way (and remain recognizable day by day).

In the center of the attached screen shot (DMI Sentinel 2018-07-05 (http://ocean.dmi.dk/arctic/kennedy.uk.php)) is a small floe that looks pretty robust (and with nearly square corners - I'll call it "Cub Scout" as [when I was one] our pledge was to be "square").  Will it make it?  Currently, it is in Hall Basin, at the intersection of lines running down Petermann Fjord and following the ridge that ends at Ellesmere Island's Cape Baird. Although distinctive today, I cannot find it in yesterday's Sentinel image, although I found a 'neighbor' that traveled about 15 km in one day.
Title: Re: The Nares Strait thread
Post by: GoSouthYoungins on July 08, 2018, 10:24:49 PM
The next few days should see the north end of nares open pretty far into lincoln sea. Warmish temps and consistent wind will likely move the ice north. This movement already begun over the last 24 hours and should increase with higher winds and higher temps since the ice pack in lincoln already appears to be fairly mobile.
Title: Re: The Nares Strait thread
Post by: oren on July 09, 2018, 03:07:24 AM
Did some quick research about approx. breakup times, southern "arch" in Kane Basin unless noted otherwise:
Thanks to Tor Bejnar for locating my previous post on the subject, so I can update it for this year.  I should note - as can be inferred from the numbers - that the dates are somewhat rounded:
2007 - No arches formed.
2008 - June 10th(?)
2009 - No southern arch. Northern arch broke around June 30th.
2010 - July 10th
2011 - July 5th.
2012 - June 30th.
2013 - July 10th.
2014 - June 20th.
2015 - July 5th.
2016 - June 30th
2017 - No southern arch. Northern arch broke around May 10th.
2018 - June 30th.
Title: Re: The Nares Strait thread
Post by: Neven on July 09, 2018, 07:09:58 AM
A small list like this one, is so incredibly valuable.  :)
Title: Re: The Nares Strait thread
Post by: bairgon on July 11, 2018, 08:56:42 AM
The Lincoln polynya is opening up, but not through the normal mechanism of a bridge holding back flow down Nares. Over the last few days there has been a prevailing SW wind up Nares Strait, which is pushing back the ice in the Lincoln Sea. The polynya has reached around 2500 km^2 (50km x 50km).

This implies to me that the ice in the Lincoln Sea is very fractured. In past years I've seen it easily hold a bridge. This year, when flow was down the Strait after the bridge broke, fracture lines were evident far out into the Lincoln Sea. Now, that fractured ice is not holding. It's possible to see signs of melting in the polynya - at NASA Worldview (https://worldview.earthdata.nasa.gov/?p=arctic&l=VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2018-07-10-T00%3A00%3A00Z&z=3&v=-336048.77567671577,-831972.5728063018,-90288.77567671577,-706148.5728063018). There appear to be trailing melt from the floes and the edge of the ice is very smooth implying wave action is melting this. On the 9th the wind was 44 km/h at 3 degrees C.

The forecast for the next 5 days on Nullschool (https://earth.nullschool.net/#2018/07/15/0600Z/wind/surface/level/overlay=temp/orthographic=-77.71,83.87,3000/loc=-60.034,82.176) is continuing winds from this direction and temperatures above freezing, so this should continue to grow.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 16, 2018, 04:54:35 PM
The wind has been blowing the Kane Basin ice 'up stream' (northeastward) and the Smith Sound ice northward for the past week or so.  GIF prepared from DMI (http://ocean.dmi.dk/arctic/kane.uk.php) Sentinel images from July 9, 11 and 14 (dates are on gif). Two floes are roughly outlined to make it easier for you to following the motion.

According to Windy.com, forecast winds are mixed north and south (back and forth) this next week.
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on July 31, 2018, 08:34:52 PM
I don't watch all the time, but it seems that at last there will be some export (southward) from the Kane Basin.  DMI Sentinel (http://ocean.dmi.dk/arctic/kane.uk.php) images (July 29 and 31 gif)
Title: Re: The Nares Strait thread
Post by: oren on July 31, 2018, 09:29:26 PM
I normally follow it (rather crudely) using the AMSR2 animations posted on the melting season thread. Indeed it seems that in the last few days southward movement through the strait has resumed, after quite a while of reverse moves.
Title: Re: The Nares Strait thread
Post by: Phil. on August 06, 2018, 04:07:21 PM
I don't watch all the time, but it seems that at last there will be some export (southward) from the Kane Basin.  DMI Sentinel (http://ocean.dmi.dk/arctic/kane.uk.php) images (July 29 and 31 gif)

Looks like the 'plug' at Kane has finally broken up and there is a southward flow. The loose ice in the north should start to flush out.
http://ocean.dmi.dk/arctic/images/MODIS/Kane/20180804AQUA.jpg
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on August 06, 2018, 04:33:10 PM
The Windy.com (https://www.windy.com/?79.339,-63.842,6) wind forecast for Smith Sound and Kane Basin has the winds alternating every day from being from the north to being from the south until Friday-Saturday.  If this forecast plays out, the ice in Kane Basin will mostly move back and forth, slowly melting in place.  [Edit, reduced GIF]
Title: Re: The Nares Strait thread
Post by: Tor Bejnar on November 09, 2018, 09:22:17 PM
Nares Strait continues to be fed ice by the Lincoln Sea.  ["Here, Little Nares, have a mouthful of ice.  It's good for you.  And don't worry, there's more from where this comes from."]  Images from DMI Sentinel (http://ocean.dmi.dk/arctic/lincoln.uk.php) for Nov. 7 and 8.
Title: Re: The Nares Strait thread
Post by: uniquorn on November 09, 2018, 10:59:34 PM
'have a pinch of salt with it' ;)
Title: Re: The Nares Strait thread
Post by: Red on November 10, 2018, 10:57:15 AM
'have a pinch of salt with it' ;)

Perhaps this belongs in stupid questions but, would the saltier water cause any weakening of the ice above it if in direct contact?
Title: Re: The Nares Strait thread
Post by: uniquorn on November 11, 2018, 02:49:10 AM
'have a pinch of salt with it' ;)

Perhaps this belongs in stupid questions but, would the saltier water cause any weakening of the ice above it if in direct contact?
While the Nares Strait is open I think the export is largely due to the strong current. The similarity of the ice fracture area with the salinity model suggests that salty water from below may be part of the process. If so, it is likely to be warmer, which could cause weakening.
Title: Re: The Nares Strait thread
Post by: uniquorn on November 12, 2018, 10:25:03 PM
Worldview, viirs brightness temperature, band15n animation of Nares, nov3-12.


Title: Re: The Nares Strait thread
Post by: uniquorn on November 23, 2018, 07:13:52 PM
polarview, nov22. Polynya area a bit larger.
Title: Re: The Nares Strait thread
Post by: uniquorn on November 23, 2018, 10:59:58 PM
Oscillating ice at the north end of the Kane basin.
Worldview, brightness temperature,band15,night, nov1-23
Title: Re: The Nares Strait thread
Post by: uniquorn on November 28, 2018, 01:21:27 PM
Still quite clear over the Nares/Lincoln sea so a continuation of Worldview, viirs brightness temperature, band15n animation, nov14-28. Arches keep forming and collapsing.
Title: Re: The Nares Strait thread
Post by: uniquorn on December 11, 2018, 11:31:06 PM
So the big floe looks like it popped out like a cork over the last 3 days.
Worldview, viirs bt15n, dec5-10
Polarview dec11