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Stephan

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Re: The Nares Strait thread
« Reply #1650 on: May 05, 2019, 05:13:20 PM »
Comparing the speed of the front and the rear edge of VBC the front is (eyeballing) around 35% faster. Of course it must split somewhere.

Shared Humanity

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Re: The Nares Strait thread
« Reply #1651 on: May 05, 2019, 05:17:15 PM »
My point is that, if simply entering a slightly faster current could cleave the VBC in half, it suggests the structural integrity of the entire VBC is suspect. That sucker is going to splinter as it encounters more destructive forces in the strait.

uniquorn

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Re: The Nares Strait thread
« Reply #1652 on: May 05, 2019, 09:06:14 PM »
That looks like melt in Kane Basin. Worldview terra modis may4-5
added link https://go.nasa.gov/2DRvtPB
Hans Island temps are odd https://dataservices.sams.ac.uk/aws/
« Last Edit: May 05, 2019, 09:24:37 PM by uniquorn »

Tor Bejnar

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Re: The Nares Strait thread
« Reply #1653 on: May 05, 2019, 09:35:27 PM »
The breakage of the VBC in Lincoln Sea - DMI Sentinel image from today.  See other discussion of this floe in its own thread.
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b_lumenkraft

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Re: The Nares Strait thread
« Reply #1654 on: May 06, 2019, 09:32:41 AM »
Also remarkable, the south side these days.

01.04. to 05.05. via Terra / Modis

seaice.de

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Re: The Nares Strait thread
« Reply #1655 on: May 06, 2019, 02:32:09 PM »
A zoom on the Nares Strait using AMSR2 data 2013-2019.

https://twitter.com/seaice_de/status/1125354599282610177



Click to start animation.

b_lumenkraft

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Re: The Nares Strait thread
« Reply #1656 on: May 06, 2019, 03:48:53 PM »
Tidal movement 06.05. at 00:05h to 09:23h UTC.

Band I1, Red visible

oren

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Re: The Nares Strait thread
« Reply #1657 on: May 06, 2019, 04:09:04 PM »
A zoom on the Nares Strait using AMSR2 data 2013-2019.
Thank you for this.

Iain

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Re: The Nares Strait thread
« Reply #1658 on: May 06, 2019, 10:56:56 PM »
VBC has broken further with the rest of the FBCs (Fairly big....) separating from the arch. The grey infill looks like cloud, not refreeze - there is clear blue water in the strait
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b_lumenkraft

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Re: The Nares Strait thread
« Reply #1659 on: May 07, 2019, 09:37:20 AM »
Looking at the weather/wind/tides forecast it seems likely to me that we will see the arch expanding to the east until the weekend. Mid next week the expansion should form in the west.

Tor Bejnar

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Re: The Nares Strait thread
« Reply #1660 on: May 07, 2019, 02:47:00 PM »
I'm grateful to those who have introduced us to the effects of tides in the Nares Strait/Lincoln Sea region.  I had previously presumed it was all wind.  (I learn something new every other day.)
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Tor Bejnar

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Re: The Nares Strait thread
« Reply #1661 on: May 07, 2019, 05:43:19 PM »
In the Kane Basin these days, a floe has moved 40 km in 3 days.  (Floe outline is approximate.)  (annotated DMI Sentinel images)
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Tor Bejnar

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Re: The Nares Strait thread
« Reply #1662 on: May 07, 2019, 08:55:57 PM »
15:06 UTC
New hour, new crack. This time alongside the Greenland coastline. ...
The crack that caused almost all of the triangle of old ice along Greenland's NNW coast to move ~8 km towards Ellesmere Island appears to have lasted only a day or so.  The triangle is 'stable' once again.  I recall this triangle of old thick ice (2 years with no movement, IIRC) moving in fits and starts a year or two ago during the summer, ultimately sending most of it through Nares Strait.

None of that ice blocked Nares Strait, so I figure ice from anywhere else doesn't have a chance.
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uniquorn

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Re: The Nares Strait thread
« Reply #1663 on: May 07, 2019, 09:13:49 PM »
A zoom on the Nares Strait using AMSR2 data 2013-2019.
https://twitter.com/seaice_de/status/1125354599282610177
Thank you seaice.de. I hope you don't mind that I copied the other animation to the vbc thread.
I'm not sure about https://doi.org/10.1029/2018GL078428 for context though. I would be surprised if even 2y old wind could have caused this -> Worldview aqua modis 2017 may9-11.  ;)
The event is well documented on this thread https://forum.arctic-sea-ice.net/index.php/topic,176.msg112923.html#msg112923

added ascat 2017 day100-135. Arch collapses after very large fracture runs west to east along the CAA
« Last Edit: May 08, 2019, 01:15:53 AM by uniquorn »

magnamentis

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Re: The Nares Strait thread
« Reply #1664 on: May 07, 2019, 09:32:07 PM »
In the Kane Basin these days, a floe has moved 40 km in 3 days.  (Floe outline is approximate.)  (annotated DMI Sentinel images)

is it correct to assume that the new, way more fractured state of the ice will increase the speed of the exported ice-flow so that we can speak about a positive feedback ?
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b_lumenkraft

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Re: The Nares Strait thread
« Reply #1665 on: May 07, 2019, 09:34:32 PM »
That's a good point Magnamentis.

b_lumenkraft

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Re: The Nares Strait thread
« Reply #1666 on: May 08, 2019, 10:45:21 AM »
Last nights (03:08h - 12:26h UTC) tidal movement. Amoeba1b cracked but other than this no damage done. The horizontal movement was ~1 meter.

uniquorn

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Re: The Nares Strait thread
« Reply #1667 on: May 08, 2019, 11:19:22 AM »
<Last nights (03:08h - 12:26h UTC) tidal movement>
b_l, any chance of an unoptimised gif? It's difficult to enhance that.

b_lumenkraft

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Re: The Nares Strait thread
« Reply #1668 on: May 08, 2019, 12:00:23 PM »
The unoptimized GIF is not at all better.

Let's try another band (natural colours). Hope that helps.

Edit: (i'm just noticing that the NC band lags one or two frames at the beginning, the night band (posted above) has them)

uniquorn

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Re: The Nares Strait thread
« Reply #1669 on: May 08, 2019, 12:47:00 PM »
Thanks for both. I found gimp unoptimise :) Now I'm wondering how far out those surges go.
« Last Edit: May 08, 2019, 01:02:06 PM by uniquorn »

b_lumenkraft

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Re: The Nares Strait thread
« Reply #1670 on: May 10, 2019, 06:49:19 AM »
Looking at the weather/wind/tides forecast it seems likely to me that we will see the arch expanding to the east until the weekend. Mid next week the expansion should form in the west.

 8)

uniquorn

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Re: The Nares Strait thread
« Reply #1671 on: May 10, 2019, 11:39:39 AM »
Thick ice triangle to the right is starting to look weak. It lifted off slightly on may2.
Eastern end of huge mighty crack visible centre left.
worldview viirsbt15n may9-10. May2 here: https://go.nasa.gov/2Jw0k87

b_lumenkraft

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Re: The Nares Strait thread
« Reply #1672 on: May 11, 2019, 09:29:56 AM »
Today's new eastern cracks. RIP triangle of old(ish) ice.

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Re: The Nares Strait thread
« Reply #1673 on: May 11, 2019, 11:21:17 PM »
Slightly off topic at the moment but maybe arches form at the limit where refreeze can keep up with tidal movement.

b_lumenkraft

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Re: The Nares Strait thread
« Reply #1674 on: May 12, 2019, 05:02:25 PM »
People who like this thread also like this post:

This GIF is showing an interesting S-curvy pattern the floes take in hight of Hall Basin in Nares Strait.

In the upper part of the GIF, you can see an up and down movement caused by a tidal wave. The S-curve stays persistent.

Sentinel also clearly shows this 'track'.

(Click GIF to animate)

Any suggestions on what's causing this?

johnm33

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Re: The Nares Strait thread
« Reply #1675 on: May 12, 2019, 08:02:35 PM »
"any suggestions"? there seems to be a strong current coming in from the Atlantic, I suspect that water has a self similar energetic potential, so as it's forced south, on the eastern side, it spins itself into vortices which reach up to the surface and accelerate the surface water flow on the western side... maybe
Sometimes when there's a powerful throughput standing waves appear south of Kane, never been sure whether these are actually in the water or cloud effects from turbulence.
added
 I guess a decent test would be if the fast ice on the eastern side breaks out from the north.
« Last Edit: May 12, 2019, 08:14:34 PM by johnm33 »

b_lumenkraft

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Re: The Nares Strait thread
« Reply #1676 on: May 12, 2019, 08:10:19 PM »
Standing waves! That makes sense.

Thanks John! :)

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Re: The Nares Strait thread
« Reply #1677 on: May 13, 2019, 09:54:35 AM »
Next This weeks weather forecast still indicates an expanding of the arch towards the west midweek. Temperatures are around -10˚C to -5˚C the whole week, so minor refreezing could happen, i doubt an effect caused by this though. Wind pattern during the whole week indicates accelerating floe drift.

Edit!
« Last Edit: May 14, 2019, 09:54:30 AM by b_lumenkraft »

b_lumenkraft

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Re: The Nares Strait thread
« Reply #1678 on: May 14, 2019, 09:53:40 AM »
The second day in a row you can't really see anything due to cloud cover. Meh -.-

Niall Dollard

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Re: The Nares Strait thread
« Reply #1679 on: May 14, 2019, 11:37:07 PM »
I take it at this stage it is far too late for a blocked Nares Strait this year. After March had passed, I thought the possibility would be slim (despite the entertainment provided by the "very big chunks")  :)

So this is an updated list of the arch start date. (Arches that is within the Strait and not temporary hold ups in the Lincoln Sea):

2019 - No arch
2018 - March 1st
2017 - No arch (in the strait proper)
2016 - December 6th (2015)
2015 - February 13th
2014 - January 5th (northern arch started - southern just after)
2013 - November 8th (2012)
2012 - December 6th (2011)
2011 - January 29th
2010 - No arch
2009 - Visible sat image shows arch at extreme north end of channel on March 10. Start date was sometime before this.
2008 - April 1st
2007 - No arch

From what I can see, 2010 was also a no arch year. From visible satellite imagery, it looks free flowing from March 1st, but can't be certain that there may have been arches earlier in that year - but that's all a bit academic anyway because any worthwhile arch should be capable of holding through the spring and this did not happen in 2010.

This NASA report from early in 2010, "found that 2007 was a unique year – the only one on record when arches failed to form, allowing ice to flow unobstructed through winter and spring. Despite Nares' narrow width, the team reports that in 2007, ice loss through Nares equaled more than 10 percent of the amount emptied on average each year through the wider Fram Strait."

So 2007 has now been joined by 2010, 2017 and 2019.
« Last Edit: May 15, 2019, 12:06:40 AM by Niall Dollard »

magnamentis

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Re: The Nares Strait thread
« Reply #1680 on: May 15, 2019, 12:20:24 AM »
I take it at this stage it is far too late for a blocked Nares Strait this year. After March had passed, I thought the possibility would be slim (despite the entertainment provided by the "very big chunks")  :)

So this is an updated list of the arch start date. (Arches that is within the Strait and not temporary hold ups in the Lincoln Sea):

2019 - No arch
2018 - March 1st
2017 - No arch (in the strait proper)
2016 - December 6th (2015)
2015 - February 13th
2014 - January 5th (northern arch started - southern just after)
2013 - November 8th (2012)
2012 - December 6th (2011)
2011 - January 29th
2010 - No arch
2009 - Visible sat image shows arch at extreme north end of channel on March 10. Start date was sometime before this.
2008 - April 1st
2007 - No arch

From what I can see, 2010 was also a no arch year. From visible satellite imagery, it looks free flowing from March 1st, but can't be certain that there may have been arches earlier in that year - but that's all a bit academic anyway because any worthwhile arch should be capable of holding through the spring and this did not happen in 2010.

This NASA report from early in 2010, "found that 2007 was a unique year – the only one on record when arches failed to form, allowing ice to flow unobstructed through winter and spring. Despite Nares' narrow width, the team reports that in 2007, ice loss through Nares equaled more than 10 percent of the amount emptied on average each year through the wider Fram Strait."

So 2007 has now been joined by 2010, 2017 and 2019.

probably random but years with either very early or no arch have had the lowest minimums, for what it's worth, just an impression to share for those who have a chance and the knowhow to ponder over  the possibility whether things are related. ;)
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oren

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Re: The Nares Strait thread
« Reply #1681 on: May 15, 2019, 05:09:23 AM »
Thanks for this important list Niall.
I personally prefer to record the dates of Lincoln sea "arches" even if they don't hold through the season, as I believe they do have a stabilizing effect on the region and they delay export.
This year had such a blockage for about one month during Feb-Mar.
2010 seems to have formed a quite stable "arch" in the Lincoln Sea from March 12th to April 16th, but it broke down from April 17th onward due to a major "crackocalypse". So it was quite similar to this year in duration and in the very early breakup date before the melting season arrives in the area.
2007 had several blocking attempts but the longest was barely 10 days (Apr 27th - May 6th), so effectively it never closed.
2017 IMHO was somewhat different, as it had a Lincoln blockage which held for at least two months (slowly widening during the period) and broke down on May 9th - an early date but still a different behavior from the others listed above.

b_lumenkraft

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Re: The Nares Strait thread
« Reply #1682 on: May 15, 2019, 09:02:50 AM »
For the record, one month of thick ice grinding.

via NASA Worldview, Nighttime Imagery (Day/Night Band, Enhanced Near Constant Contrast) Suomi NPP / VIIRS

(Click GIF to animate)

Alphabet Hotel

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Re: The Nares Strait thread
« Reply #1683 on: May 15, 2019, 09:18:17 PM »
Animation of the last two days of Sentinel-1 images. It's like a giant vacuum just sucking the ice down the strait. Looks like the ice to the east is moving again too. Click to animate, I guess. (This is my first animated GIF.)

GoSouthYoungins

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Re: The Nares Strait thread
« Reply #1684 on: May 16, 2019, 04:57:36 AM »
The last week has shown that it is extremely unlikely anything will stop the nares slip-n-slide from shooting ice full speed into the baffin sea.

Some huge chucks have been laughed at by the mouth of the strait as it shatters them and sucks them in. I think that water in the strait (and probably lincoln sea to some extent) is very salty and very warm (relatively). There has been melt in the strait and the solar insolation is just getting started and will be stronger for the next 2 months.


I think the question has to be asked...

WILL NARES EVER CLOSE AGAIN?!?
big time oops

b_lumenkraft

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Re: The Nares Strait thread
« Reply #1685 on: May 16, 2019, 11:26:27 AM »
WILL NARES EVER CLOSE AGAIN?!?

I would guess not this year at least...

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Re: The Nares Strait thread
« Reply #1686 on: May 16, 2019, 11:30:26 AM »
High tide coming up Monday 20 May 11:29 AM EDT (UTC -4.0hrs) with 0.76 meters.

There is still massive cloud cover over the arch making it hard to see movements at the moment.

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Re: The Nares Strait thread
« Reply #1687 on: May 16, 2019, 11:42:48 AM »

WILL NARES EVER CLOSE AGAIN?!?
[/quote]


A question I first asked last June .. this winter and spring have been the answer .. it may never close again .. without human intervention . b.c.
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Re: The Nares Strait thread
« Reply #1688 on: May 16, 2019, 01:43:51 PM »

WILL NARES EVER CLOSE AGAIN?!?


A question I first asked last June .. this winter and spring have been the answer .. it may never close again .. without human intervention . b.c.

You just reminded me of a Sci Fi story I read some time ago. One of the side stories was of the effort to slow down the roaring tide of slushy ice that Jakobshavn had become. They were trying to weave a net made from carbon fiber across the mouth of the former glacier, now a cataract of slush and ice chunks that shook the earth and could be heard from many miles away. They weren't having much success, either. Trying to close the Nares would probably be just as futile.

oren

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Re: The Nares Strait thread
« Reply #1689 on: May 16, 2019, 02:16:36 PM »
Yes, I think the Nares will close again for a few months next year or one of the years following. No way we have seen the last real closing of the Nares.
(Of course it also depends on the definition of closure.)

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Re: The Nares Strait thread
« Reply #1690 on: May 16, 2019, 07:17:48 PM »
The North is still in cloud cover. It appears the west side of the arch has become active again cracking wise. Not 100% sure though.

There is some action in the Kane Basin.

Today, 03:40h vs 10:27h UTC

GoSouthYoungins

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Re: The Nares Strait thread
« Reply #1691 on: May 17, 2019, 06:06:04 AM »
Yes, I think the Nares will close again for a few months next year or one of the years following. No way we have seen the last real closing of the Nares.
(Of course it also depends on the definition of closure.)

I'm curious why you think so. Seems to me like ice in lincoln sea will only be in weaker, the water below will only be warmer and saltier, and the atmosphere warmer as well. Of course, there is a good likelihood there will be significant pattern changes in the area during the next decade...so who knows. But why, "no way"? (And based on what definition of "closing" do you mean that?)
big time oops

oren

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Re: The Nares Strait thread
« Reply #1692 on: May 17, 2019, 01:44:41 PM »
The local climate changes are slow moving and the weather is random. Nares has been known to close in the last few years despite poor conditions in the Lincoln Sea, with some arches forming in the south (Kane) and some in the north (Lincoln). Temps in Feb are around -35C and with a bit of proper wind to counter the strong current an "arch" can freeze in place, and with some luck hold for a few months.
IMHO even a two-month holdup is a closure of the strait, though a one-month stint is not enough.

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Re: The Nares Strait thread
« Reply #1693 on: Today at 09:33:58 AM »
Yesterdays Nasa Worldview [1] was the first clearish shot for some days now making the shape of the arch visible. A big boi in the entrance, which broke in pieces today (for what i can see in the Slider shot at 5:48h UTC [2]).

[1] First pic: Nighttime Imagery (Day/Night Band, Enhanced Near Constant Contrast) Suomi NPP / VIIRS
[2] Second pic: Rammb Slider (Day/Night Band), rotated