The Nares Strait thread

[Sigmetnow]

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!

[gfwellman]

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)?

[Neven]

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.

Here's my post on the collapse on June 17th 2011. And last year on June 27th. Here's the first animation 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

[Sigmetnow]

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.

[Andreas Muenchow]

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 

[Espen]

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

[TerryM]

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

[Jim Hunt]

Yesterday's view of the area from Terra. See NASA Worldview 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.

[Sigmetnow]

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

The  "05-04-2013 [TERRA]"   and   "05-04-2013 [AQUA]"  images look particularly suggestive.  (If one can say that about ice.)

[Espen]

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.

[Espen]

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

[Sigmetnow]

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).

[FrankD]

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.

[Espen]

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

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

[Peter Ellis]

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.

[Mike Fliss]

Yes, Espen is correct.  There are 2 pinpoints of open water off the cape.  A polynya frequently opens in that area. 

[Espen]

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

[Sigmetnow]

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

[Espen]

For those thirsty? A decent watering hole is appearing of Kap Jackson (Washington Land) :

http://rapidfire.sci.gsfc.nasa.gov/cgi-bin/imagery/single.cgi?image=crefl2_143.A2013144093500-2013144094000.500m.jpg

[TerryM]

Using the Arctic.io Split Zoom feature I was amazed at how few changes have taken place in Nares over the last month.


Terry

[Espen]

Terry;

Nothing much except for the Nite Owls

[Peter Ellis]

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

8th April: the arch is "filling in" with new ice
http://rapidfire.sci.gsfc.nasa.gov/imagery/subsets/?subset=Arctic_r03c02.2013159.terra

[TerryM]

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

[icebgone]

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.

[Peter Ellis]

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%.

[Espen]

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

[Whit]

The break-up in the Lincoln-Sea is quite interesting. It seems like the ice there is much more vulnerable than last season.

[Shared Humanity]

The break-up in the Lincoln-Sea is quite interesting. It seems like the ice there is much more vulnerable than last season.

Isn't this some of the thickest MYI?

[Espen]

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.

[TerryM]

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

[Espen]

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.

[TerryM]

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

[anonymous]

Actually 3 years: arctic.io/split-zoom/2010-06-20;2013-06-20

[TerryM]

Actually 3 years: arctic.io/split-zoom/2010-06-20;2013-06-20

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

[Laurent]

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

[Espen]

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

[Lynn Shwadchuck]

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

[Espen]

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

[Andreas Muenchow]

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

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/

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.

[TerryM]

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

[Andreas Muenchow]

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.

[Espen]

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

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/

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.

[TerryM]

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

[Patrick]

...

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

[Espen]

Patrick,

Yes and we have more cracks inside Kennedy Channel / Nares Strait in the vicinity of Franklin Island and Crozier Island:

[TerryM]

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

[Espen]

Recent cracking near Franklin Island:

[Espen]

Only days away from the ice collapse in Nares Strait:

[Tor Bejnar]

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.

[Espen]

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: