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uniquorn

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Re: The Nares Strait thread
« Reply #2450 on: December 29, 2020, 03:14:16 PM »
Regarding said "big block", now that the wind is blowing up the strait I noticed it is not behaving like its neighbors. It has the tendency to move away from the funnel more easily - could it be that its surface has some tall features that catch the wind in force?
Followed that MYI with the red dot over the last few months. In some ways the ice is its own worst enemy. The animation is best viewed at half speed.
Yesterday's polarview S1B

oren

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Re: The Nares Strait thread
« Reply #2451 on: December 29, 2020, 04:17:22 PM »
Thanks for this update uniquorn. Turns out Big Block did not really escape the funnel, but eventually was turned around and brought back during autumn, and now it's Big Rubble.

vox_mundi

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Re: The Nares Strait thread
« Reply #2452 on: January 06, 2021, 03:50:15 PM »
Ice Arches Holding Arctic's 'Last Ice Area' In Place Are At Risk, Researcher Says
https://phys.org/news/2021-01-ice-arches-arctic-area.html

...

G. W. K. Moore et al. Anomalous collapses of Nares Strait ice arches leads to enhanced export of Arctic sea ice, Nature Communications (2021).
https://www.nature.com/articles/s41467-020-20314-w


Sea ice concentration (%) along Nares Strait from AMSRE/2 satellite data during June.


Time series of duration (days) of ice stoppage along Nares Strait. During 2007 and 2019, indicated by the ‘o’, no arches formed.

... Recent work indicates that ice motion in the Last Ice Area, that includes the Lincoln Sea, is increasing at twice the rate as the entire Arctic Ocean14. In addition, a number of theoretical16,32 and observational8,17 studies have proposed that the stability of the Nares Strait ice arches decreases with thinning ice cover.

These results are consistent with those presented herein all of which provide additional evidence of the changing nature of the Arctic as we transition to a thinner more mobile ice pack. Results of this study also highlight that with continued Arctic warming, ice arch stability in Nares Strait as well as throughout the adjacent CAA will decrease resulting in more frequent transport of Arctic Ocean multi-year to southerly latitudes7, that will have negative implications for the maritime industry33,34 as well as impacting food security and other traditional activities for indigenous communities in the Arctic35.

The current configuration of the North Water Polynya, as a latent heat polynya, depends on the presence of the Nares Strait ice arches36 to restrict the southward flux of thick multi-year ice along Nares Strait. This allows the strong winds and ocean currents that occur in the vicinity of Smith Sound23,37 to advect thin ice away allowing the polynya to form. It follows that a weakening of the Nares Strait ice arches may impact the North Water Polynya leading to regional changes in primary and secondary production that will be felt throughout the entire food chain.
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gerontocrat

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Re: The Nares Strait thread
« Reply #2453 on: January 06, 2021, 04:36:04 PM »
The arch and the ice upstream from it nicely locked solid by the looks of it.
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vox_mundi

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Re: The Nares Strait thread
« Reply #2454 on: January 06, 2021, 04:46:25 PM »
Like the article says; 5 months till June.
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gerontocrat

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Re: The Nares Strait thread
« Reply #2455 on: January 10, 2021, 09:48:56 PM »
BBC science article @ https://www.bbc.co.uk/news/science-environment-55594585 telling us of that which ASIF members are already cognisant.

Climate change: Weakened 'ice arches' speed loss of Arctic floes


Quote
....what Prof Moore's and colleagues' satellite research has shown is that these structures are becoming less reliable barriers.
They are forming for shorter periods of time, and the amount of frozen material allowed to pass through the strait is therefore increasing as a consequence.

"We have about 20 years of data, and over that time the duration of these arches is definitely getting shorter," Prof Moore explained.

"We show that the average duration of these arches is decreasing by about a week every year. They used to last for 250-200 days and now they last for 150-100 days. And then as far as the transport goes - in the late 1990s to early 2000s, we were losing about 42,000 sq km of ice every year through Nares Strait; and now it's doubled: we're losing 86,000 sq km."

Prof Moore says we need to hang on to the oldest ice in the Arctic for as long as possible.

If the world manages to implement the ambition of the Paris climate accord and global warming can be curtailed and reversed, then it's the thickest ice retained along the top of Canada and Greenland that will "seed" the rebound in the frozen floes.

The area of oldest, thickest ice, he adds, is also going to be an important refuge for those species that depend on the floating floes for their way of life - the polar bears, walruses and seals.

"My concern is that this last ice area may not last for as long as we think it will. This is ice that is five, six, even 10 years old; so if we lose it, it will take a long time to replenish even if we do eventually manage to cool the planet."

Prof Moore and colleagues have published their latest research in the journal Nature Communications***.

***   https://www.nature.com/articles/s41467-020-20314-w

Open access - some super stuff in it.





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Niall Dollard

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Re: The Nares Strait thread
« Reply #2456 on: January 11, 2021, 01:12:33 AM »
Yes an interesting read, Gero. (Vox mundi has also posted a link to this Nature article early in this thread).

I do have one gripe.It is an issue that I have seen mentioned on the ASIF several times before - which is how old these papers are by the time they get published.

This paper on Nature Communications was published 4th Jan 2021 and yet has no mention of 2020. The Nares arches were done and dusted by July 2020. 7 months later and no inclusion of the 2020 data. 2017 and 2019 were bad years for arch formation. In 2020 the arch held for approx 200 days, which is more like the longevity arches of old. It is quite likely the arch in 2021 will last over 200 days also.

I have already put a calculation on arch longevity (2007-2020), within the Nares Strait, in post 2448 of this thread. Because of bad years 2017 and 2019 the 5 year average has dropped considerably but 2020 and 2021 will make it rise again (a little).

Like for so much of the Arctic, time is running out for the arches in the Nares. I was surprised that for both 2020 and now 2021, arch formation has begun relatively early. Whilst the Nature Comms article is a good read. It is not up to date.   

interstitial

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Re: The Nares Strait thread
« Reply #2457 on: January 11, 2021, 02:10:35 PM »
Yes an interesting read, Gero. (Vox mundi has also posted a link to this Nature article early in this thread).

I do have one gripe.It is an issue that I have seen mentioned on the ASIF several times before - which is how old these papers are by the time they get published.

This paper on Nature Communications was published 4th Jan 2021 and yet has no mention of 2020. The Nares arches were done and dusted by July 2020. 7 months later and no inclusion of the 2020 data. 2017 and 2019 were bad years for arch formation. In 2020 the arch held for approx 200 days, which is more like the longevity arches of old. It is quite likely the arch in 2021 will last over 200 days also.

I have already put a calculation on arch longevity (2007-2020), within the Nares Strait, in post 2448 of this thread. Because of bad years 2017 and 2019 the 5 year average has dropped considerably but 2020 and 2021 will make it rise again (a little).

Like for so much of the Arctic, time is running out for the arches in the Nares. I was surprised that for both 2020 and now 2021, arch formation has begun relatively early. Whilst the Nature Comms article is a good read. It is not up to date.   

It takes time to gather the data. It takes time to write and polish. If you go back and add more data you have to rewrite it and polish again. Then you submit It takes time for an initial judgement by the publication. It takes time for reviewers (they are volunteers so reviewing is not their most pressing task). If their are any corrections or clarifications those take time. Their are usually at least some clarifications. It takes time for publication to give final approval. After final approval it has to be determined when to publish it. It doesn't always go into the next issue. Depending on the journal between first submission and publication can take half a year or more. The time it takes can vary greatly and on occasion things languish. These publications may or may not have full time staff.

uniquorn

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Re: The Nares Strait thread
« Reply #2458 on: January 11, 2021, 08:41:13 PM »
Still some tidal movement in the Robeson Channel, https://go.nasa.gov/3siankW  jan2-10
rammb JPSS, band I4, jan2-11

Niall Dollard

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Re: The Nares Strait thread
« Reply #2459 on: January 27, 2021, 09:07:12 PM »
A sliver breaks off the Ellesmere side. It looks like only recent ice.

Alumril

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Re: The Nares Strait thread
« Reply #2460 on: February 24, 2021, 09:28:13 PM »


G. W. K. Moore et al. Anomalous collapses of Nares Strait ice arches leads to enhanced export of Arctic sea ice, Nature Communications (2021).
https://www.nature.com/articles/s41467-020-20314-w


Presentation by Kent Moore now available on youtube covering this paper.


uniquorn

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Re: The Nares Strait thread
« Reply #2461 on: March 07, 2021, 01:14:57 PM »
Movement at the Lincoln Sea entrance to the strait. 
rammb JPSS band I5 Mar5-7

Niall Dollard

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Re: The Nares Strait thread
« Reply #2462 on: March 10, 2021, 12:41:13 PM »
Quite a few peculiarly rectangular shaped light coloured blocks at the entrance to the Nares Strait.
« Last Edit: March 10, 2021, 12:49:12 PM by Niall Dollard »

Shared Humanity

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Re: The Nares Strait thread
« Reply #2463 on: March 10, 2021, 08:13:46 PM »
Thick MYI remnants?

Espen

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Re: The Nares Strait thread
« Reply #2464 on: March 12, 2021, 10:36:43 AM »
Thick MYI remnants?

More likely icebergs from Steensby and Ryder glaciers? There were some bergs released from the fjords in 2020.
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Jim Hunt

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Re: The Nares Strait thread
« Reply #2465 on: March 26, 2021, 03:48:48 PM »
A chip has just flaked off the Greenland side of the southern arch.

Near the 72W line if it's not obvious at first sight:
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Re: The Nares Strait thread
« Reply #2466 on: March 26, 2021, 07:47:59 PM »
Hycom believes the ice has been flowing consistantly thru Nares and the main CAA channels.  I think the impression of an arch is actually the large volumes of fresh water rising after coming out  at the base of Humboldt glacier, and the seafloor of the basin. The water cools about 2.5 degrees per km of water depth as it rises, just like a gas does under expansion, causing nucleation of a weak grease or platelet skin on the surface south of the "Arch".

oren

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Re: The Nares Strait thread
« Reply #2467 on: March 26, 2021, 07:57:27 PM »
OTG, what now? Denying the existence of the Nares Arch?

Niall Dollard

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Re: The Nares Strait thread
« Reply #2468 on: March 26, 2021, 08:36:00 PM »
OTG, what now? Denying the existence of the Nares Arch?

Lol. Maybe the arch has moved 3km underwater !

But joking aside, strange choice of language and punctuation by OTG. "impression of an arch " and then placing arch in inverted commas as if to suggest it is dubious.

Jim Hunt

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Re: The Nares Strait thread
« Reply #2469 on: March 26, 2021, 09:13:11 PM »
OTG, what now? Denying the existence of the Nares Arch?

And there was me thinking Sentinel 1 was the gold standard when it comes to establishing the existence of sea ice?

The only way we are going to get realistic metrics on Area, albedo etc is to analyse the S1 radar tiles...

Theres been quite a lot of S1 imagery on the forum which can be useful.
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Jim Hunt

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Re: The Nares Strait thread
« Reply #2470 on: March 26, 2021, 09:14:35 PM »
Hycom believes the ice has been flowing consistantly thru Nares and the main CAA channels

Evidently Hycom is mistaken.
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Stephan

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Re: The Nares Strait thread
« Reply #2471 on: March 26, 2021, 10:11:22 PM »
I do not see any HYCOM arrow in the Nares Strait.
It is too late just to be concerned about Climate Change

oren

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Re: The Nares Strait thread
« Reply #2472 on: March 26, 2021, 10:36:04 PM »
Hycom's arrow is possibly showing the ice that is constantly created in the polynia south of the Arch, and is then carried south with the current. OTOH, Hycom could simply be wrong.

Niall Dollard

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Re: The Nares Strait thread
« Reply #2473 on: March 27, 2021, 12:16:48 PM »
On 26th March, a crack has appeared right across the Robeson Channel at the top of the Nares Strait. It runs almost right across from Greenland to Ellesmere and is about 1 km wide.

Shows up on Worldview and Sentinel images (although it is difficult yet to see it on DMI. Maybe it will show on today's DMI image.

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Re: The Nares Strait thread
« Reply #2474 on: March 27, 2021, 01:54:01 PM »
On 26th March, a crack has appeared right across the Robeson Channel at the top of the Nares Strait. It runs almost right across from Greenland to Ellesmere and is about 1 km wide.

Shows up on Worldview and Sentinel images (although it is difficult yet to see it on DMI. Maybe it will show on today's DMI image.
There was a strong wind through Nares that seems to have blown away the ice in the Lincoln sea. This proves IMHO how weak and thin the ice is there, and all along the CAAAGC...
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gerontocrat

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Re: The Nares Strait thread
« Reply #2475 on: March 27, 2021, 02:55:25 PM »
On 26th March, a crack has appeared right across the Robeson Channel at the top of the Nares Strait. It runs almost right across from Greenland to Ellesmere and is about 1 km wide.

Shows up on Worldview and Sentinel images (although it is difficult yet to see it on DMI. Maybe it will show on today's DMI image.
There was a strong wind through Nares that seems to have blown away the ice in the Lincoln sea. This proves IMHO how weak and thin the ice is there, and all along the CAAAGC...
Looking at the DMI images for the Lincoln Sea at and beyond the entrance of the  Nares Strait shows cracks formed twixt the 23rd and 26th March and a general and relatively small northward shift.

First signs of the melting season?

click gif to start and enlarge

« Last Edit: March 27, 2021, 03:03:31 PM by gerontocrat »
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Freegrass

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Re: The Nares Strait thread
« Reply #2476 on: March 27, 2021, 03:12:55 PM »
First signs of the melting season?
I don't think it's melting yet. It's just prove of weak ice...
Do katabatic winds have an impact there? Are they the cause of the mega crack?

Guess that's a little OT here. Can you post this gif in the melting thread?
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Re: The Nares Strait thread
« Reply #2477 on: April 06, 2021, 09:26:29 PM »
Lincoln Sea April 6 2021, cracks all the way down to the mouth of Nares Strait from the  east coast of Greenland (Flade Isblink) and probably all the the west to Beaufort Sea, pretty impressive?

Click on image to enlarge!
« Last Edit: April 06, 2021, 09:33:56 PM by Espen »
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be cause

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Re: The Nares Strait thread
« Reply #2478 on: April 06, 2021, 10:08:29 PM »
Indeed Espen , all the way to Beaufort there is a significant crack , mostly @ 10km wide and up to 20km in places . It has opened largely in the last 4 days . Worldview has a great view of the whole today ...

https://go.nasa.gov/2PIfVqH - click the link ..

Beaufort has it's own ongoing crackopalypse .. b.c.
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 + 2 = 2021 + 1 =  ' if only we could have seen it coming ' ...

gerontocrat

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Re: The Nares Strait thread
« Reply #2479 on: April 06, 2021, 10:43:15 PM »
Here is a little gif from DMI images of Lincloln

click to start & click again for even bigger, runs 5 times.
"Para a Causa do Povo a Luta Continua!"
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Espen

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Re: The Nares Strait thread
« Reply #2480 on: April 06, 2021, 11:17:45 PM »
Indeed Espen , all the way to Beaufort there is a significant crack , mostly @ 10km wide and up to 20km in places . It has opened largely in the last 4 days . Worldview has a great view of the whole today ...

https://go.nasa.gov/2PIfVqH - click the link ..

Beaufort has it's own ongoing crackopalypse .. b.c.

I will add to that the crack is reaching from Barents Sea all the way to at least Beaufort Sea, or some + 4.000 km, wonder where this will end, and it is only April 6?
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FredBear

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Re: The Nares Strait thread
« Reply #2481 on: April 07, 2021, 06:24:03 AM »
Thumbing through the years Worldview images for April 6 I see various cracks in the central Arctic ice cover. A few years have apparently got more solid ice but in most years weaknesses are apparent, with different areas showing the greatest movements. In many years there are patches that show a flow away from the more extreme weaknesses. The crack mentioned this year is not the worst that has appeared especially as the Nares Strait is not open(?).
One thing I do see this year is the flow of cloud streets between Scandinavia and Greenland showing the wind consistently blowing from the north at this time, which is more noticeable this year than in previous years. Somewhere warmer air must be flowing north    .    .    .

gerontocrat

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Re: The Nares Strait thread
« Reply #2482 on: April 09, 2021, 07:38:57 PM »
Some movement below the arch in Kane

click to start (runs 6 times)
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gerontocrat

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Re: The Nares Strait thread
« Reply #2483 on: April 14, 2021, 03:26:10 PM »
Fascinating to watch ice flowing down Kane to Baffin Bay while the arch itself and above towards Lincoln remains solid as as a rock. Looks like the strait below the Arch getting really empty of ice floes

Can SW winds shove a new load of ice from Baffin Bay back up the Nares Strait to the arch?
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Niall Dollard

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Re: The Nares Strait thread
« Reply #2484 on: April 14, 2021, 07:55:29 PM »
Fascinating to watch ice flowing down Kane to Baffin Bay while the arch itself and above towards Lincoln remains solid as as a rock. Looks like the strait below the Arch getting really empty of ice floes

Can SW winds shove a new load of ice from Baffin Bay back up the Nares Strait to the arch?

Yes it is fascinating Gero!

So long as the usually persistent northeast or north winds are not blowing down the channel, new ice can form below the arch. SW winds would help to jam it up against the arch. Usually though the NE winds get going again and it breaks away down the Baffin and if the NE winds are especially strong the full North Water Polynya can open up.

That said some years a second (solid) arch can form below the first arch. Back in March 2018 an arch started to form in the Kane Basin around March 1st. Then about 2 weeks later a second arch started to form a bit below the 1st arch. This second arch did not break away (as is more typical) and held on until the summer.

See this old post from up thread:

https://forum.arctic-sea-ice.net/index.php/topic,176.msg147106.html#msg147106