Arctic Sea Ice : Forum

Cryosphere => Arctic sea ice => Topic started by: ajouis on July 29, 2019, 10:23:23 AM

Title: The caa-greenland mega crack
Post by: ajouis on July 29, 2019, 10:23:23 AM
It is unprecedented, i think to have such a huge crack at that place, this early. This thread is for data, speculation, and potential causes and consequences of this event.
To my knowledge only the nares restarting to export is blocking a further continuation of the crack at the moment
Title: Re: The caa-greenland mega crack
Post by: bluice on July 29, 2019, 11:13:50 AM
It's probably reasonable to expect The Crack to become a standard in future melt seasons. I wonder how this will affect future minimums and especially the somewhat arbitrary 1 million km2 BOE threshold.

If Northern CAA & Greenland can no longer be counted as the last bastion of thick MYI, do we such a place anywhere in the Arctic?  Will the last remaining ice be an ice island circulating at the pole, and if so, is such development a start to a BOE or the Arctic Ocean to become a seasonally open sea.

Interesting.
Title: Re: The caa-greenland mega crack
Post by: be cause on July 29, 2019, 11:24:21 AM
the craic was good in 2009 .. :) .. b.c.
Title: Re: The caa-greenland mega crack
Post by: Coffee Drinker on July 29, 2019, 11:37:50 AM
I go with ice island circling around the pole. Northern Greenland can get surprisingly hot.
Title: Re: The caa-greenland mega crack
Post by: ajouis on July 29, 2019, 11:54:52 AM
the craic was good in 2009 .. :) .. b.c.
Do you have pics?
Title: Re: The caa-greenland mega crack
Post by: be cause on July 29, 2019, 11:56:56 AM
the craic was good in 2009 .. :) .. b.c.
Do you have pics?
sorry,no  .. Worldview does
Title: Re: The caa-greenland mega crack
Post by: Lou on July 29, 2019, 01:51:17 PM
I won't pollute this topic with my wildly uneducated guesses about the future of this crack, but I do want to say that watching such things arise and develop as we slide ever closer to the first BOE and beyond is one of the more grimly fascinating parts of watching the doings on top of the world.
Title: Re: The caa-greenland mega crack
Post by: Sterks on July 29, 2019, 03:21:27 PM
This is not unprecedented. Seen several times. One year there was one as big or bigger so that a loon decided to take precedence on its discovery and put his name on it.
Of course it resealed.
Title: Re: The caa-greenland mega crack
Post by: Rich on July 29, 2019, 04:16:34 PM
I think le' crack is a big deal as a leverage point for wind.

My BOE vision involves a couple of weeks of steady late season 30+ knot winds pushing the pack toward Fram.

We're set in a few days to at least get a glimpse of what that would look like. Theoretically, it could still happen this year. Who knows what the weather lottery will produce?
Title: Re: The caa-greenland mega crack
Post by: Tor Bejnar on July 29, 2019, 04:48:31 PM
I've seen open water just north of the CAA several times, and north of Greenland last year, but having a nearly continuous stretch of open water along the entire North American continent, and for as long a period of time this year, is unprecedented, I believe.   Polynyas that recur in certain locations are often named, such as the North Water Polynya (https://en.wikipedia.org/wiki/North_Water_Polynya).  A 'full' list of Canadian polynyas [plus some inAlaska, Greenland and eastern Russia] (http://maps.canadiangeographic.ca/canadas-polynyas/) .

Should this become a feature, I've proposed calling it the NAC: North American Crack.  Of course we could call it McCAG: Mega-crack - Canadian Arctic/Greenland: this doesn't 'look' like any other abbreviation...  Movement of ice along this boundary, of course, happens 'all' the time.  What is less usual is for the ice to pull away (and melt) along most of this boundary at one time, so maybe the NACP:  North American Coastal Polynya.

The Canadian list (http://maps.canadiangeographic.ca/canadas-polynyas/) of polynyas identifies the location of un-named "major shore lead polynyas", including one along the entire North American continent.  So maybe the NASLP: North American Shore Lead Polynya.

See more discussion of polynya in Wikipedia (https://en.wikipedia.org/wiki/Polynya), Encyclopedia Britannica (https://www.britannica.com/science/polynya) and elsewhere.

[I share my opinions and you choose!]
Title: Re: The caa-greenland mega crack
Post by: Sterks on July 29, 2019, 05:08:27 PM
OK that may be true. Maybe it's a new feature enhanced by the very weak ice over there compared to pre-2010s
Yet I am unable to see the potential effects a frequent reappearance can have. Not saying it CAB have...
Title: Re: The caa-greenland mega crack
Post by: Pmt111500 on July 29, 2019, 05:23:08 PM
Ice is taking a shore leave. Likely comes back to serve next spring as the albedo enhancer. But the job is dull and increasingly difficult, so might leave alltogether some spring.
Title: Re: The caa-greenland mega crack
Post by: Rich on July 29, 2019, 05:46:32 PM
I've seen open water just north of the CAA several times, and north of Greenland last year, but having a nearly continuous stretch of open water along the entire North American continent, and for as long a period of time this year, is unprecedented, I believe.   Polynyas that recur in certain locations are often named, such as the North Water Polynya (https://en.wikipedia.org/wiki/North_Water_Polynya).  A 'full' list of Canadian polynyas [plus some inAlaska, Greenland and eastern Russia] (http://maps.canadiangeographic.ca/canadas-polynyas/) .

Should this become a feature, I've proposed calling it the NAC: North American Crack.  Of course we could call it McCAG: Mega-crack - Canadian Arctic/Greenland: this doesn't 'look' like any other abbreviation...  Movement of ice along this boundary, of course, happens 'all' the time.  What is less usual is for the ice to pull away (and melt) along most of this boundary at one time, so maybe the NACP:  North American Coastal Polynya.

The Canadian list (http://maps.canadiangeographic.ca/canadas-polynyas/) of polynyas identifies the location of un-named "major shore lead polynyas", including one along the entire North American continent.  So maybe the NASLP: North American Shore Lead Polynya.

See more discussion of polynya in Wikipedia (https://en.wikipedia.org/wiki/Polynya), Encyclopedia Britannica (https://www.britannica.com/science/polynya) and elsewhere.

[I share my opinions and you choose!]


I like the initiative to find a name for this feature. My understanding is that polynya refers to open water completely surrounded by ice and the crack doesn't meet that definition to the west.

I'm cool with crack or NAC until it gets bigger. When it hits 50k km2 or 100k km2, it become something else.

How about CABCOW? (Central Arctic Basin Coastal Open Water)

This is pretty much covers the entire region where the CAB comes into contact with land ( excluding small features like Svalbard and FJL. )
Title: Re: The caa-greenland mega crack
Post by: sailor on July 29, 2019, 06:03:04 PM
I think le' crack is a big deal as a leverage point for wind.

My BOE vision involves a couple of weeks of steady late season 30+ knot winds pushing the pack toward Fram.

We're set in a few days to at least get a glimpse of what that would look like. Theoretically, it could still happen this year. Who knows what the weather lottery will produce?
I don't understand what you mean... if the wind pushes steadily the pack toward Fram, the natural tendency of the ice will be to be steered by Coriolis force to the right of the winds, and close whatever gap there is between the ice and CAA/Greenland.
Unless you are thinking on a very particular circulation that I can't really see.


(ahh that was it, The GAP... Barry's Gap was it?)
Title: Re: The caa-greenland mega crack
Post by: sailor on July 29, 2019, 06:04:35 PM
OK that may be true. Maybe it's a new feature enhanced by the very weak ice over there compared to pre-2010s
Yet I am unable to see the potential effects a frequent reappearance can have. Not saying it CAB have...
Think on it as more the effect than the cause ...
I don't see it however as a feature that survives during winter. That is obvious for every one?
Title: Re: The caa-greenland mega crack
Post by: ajouis on July 29, 2019, 06:08:58 PM
OK that may be true. Maybe it's a new feature enhanced by the very weak ice over there compared to pre-2010s
Yet I am unable to see the potential effects a frequent reappearance can have. Not saying it CAB have...
could enhance ssts in the region, where thick ice is supposed to be, keeping volume down, and changing the safe ice reduit.
It might mean another change of paradigm in the arctic, which is one of the reasons why I opened this thread, to compile data to know whether this is the case, I have only been following the arctic for a couple of years, so I am only really aware of the north Greenland crack late summer last year.
Title: Re: The caa-greenland mega crack
Post by: Tor Bejnar on July 29, 2019, 07:11:35 PM
Some do define polynyas as being [completely] surrounded by sea ice.  However, "coastal polynyas (https://en.wikipedia.org/wiki/Polynya)" must be close to a coast, meaning next to land, and many of the named polynyas around Canada (http://maps.canadiangeographic.ca/canadas-polynyas/) are bounded by land on at least one side.

CABCOW's pretty good! :)

OK that may be true. Maybe it's a new feature enhanced by the very weak ice over there compared to pre-2010s
Yet I am unable to see the potential effects a frequent reappearance can have. Not saying it CAB have...
Think on it as more the effect than the cause ...
I don't see it however as a feature that survives during winter. That is obvious for every one?
I sure hope so!
Title: Re: The caa-greenland mega crack
Post by: UCMiami on July 29, 2019, 07:36:25 PM
If this becomes a more frequent yearly situation, the largest effect I could see would be changing the nature of the ice in the CAA. The CAA has been an exit route for MYI leaving the CAB late in the melt season. If the gap remains open, it suggests the winds are steadily blowing from the south and the gap could be an exit point for the ice in the CAA. The CAA would then be home of mostly FYI rather than a mixture of large thick chunks of MYI tied together with FYI.

If that happens the CAA would start melting earlier and more completely each year. Not sure if that would increase temperatures into the CAB but suspect it would.
Title: Re: The caa-greenland mega crack
Post by: Sterks on July 29, 2019, 08:47:01 PM
OK that may be true. Maybe it's a new feature enhanced by the very weak ice over there compared to pre-2010s
Yet I am unable to see the potential effects a frequent reappearance can have. Not saying it CAB have...
could enhance ssts in the region, where thick ice is supposed to be, keeping volume down, and changing the safe ice reduit.
It might mean another change of paradigm in the arctic, which is one of the reasons why I opened this thread, to compile data to know whether this is the case, I have only been following the arctic for a couple of years, so I am only really aware of the north Greenland crack late summer last year.

Yes I understand better now. However, if in summer there’s a “Garlic press” like event (strong compaction against the CAA and Greenland) expect a lot of ridged ice to occupy that breach over the shelf, delaying the reappearance  of that gap that we witness now.

 I see typical events of the Arctic (drift towards America, Fram currents) as tending to keep the thing closed and with thickened and ridge ice. I agree with sailor above there should not survive in Winter, but I think beyond, it would  typically recover thick ice.
Title: Re: The caa-greenland mega crack
Post by: binntho on July 30, 2019, 08:16:52 AM
New depths are being plumbed here (and yes, horrible pun intended). June 28 omitted for dramatic effect. (click to run)
Title: Re: The caa-greenland mega crack
Post by: Peter Ellis on July 30, 2019, 10:12:21 AM
The phrase you're looking for is "flaw lead".
Title: Re: The caa-greenland mega crack
Post by: Tor Bejnar on July 30, 2019, 05:48:32 PM
Wow, I get to learn something every other day! (in this case the terms, not the concept):flaw lead (https://en.wikipedia.org/wiki/Flaw_lead),  shore lead (https://en.wikipedia.org/wiki/Shore_lead), coastal lead
Quote
A shore lead (or coastal lead) is an oceanographic term for a waterway opening between pack ice and shore. While the gap of water may be as narrow as a tide crack if closed by wind or currents, it can be as wide as 1,000 feet (300 m). Its formation can be influenced by tidal action, or subsurface conditions, such as current and ocean floor.[2] Commonly, a shore lead is navigable by surface vessels.[3]

An opening ("lead") between pack ice and fast ice is referred to as a flaw lead.

NACL: North Am. Coastal Lead (there's a distinct taste to that)
but only when it is less that 300.01 (or is it 304.81?) meters wide. :o
NaFl: Sodium (https://en.wikipedia.org/wiki/Sodium) Flerovium (https://en.wikipedia.org/wiki/Flerovium)? I mean NAFL: North Am. Flaw Lead
this is getting dangerous
Title: Re: The caa-greenland mega crack
Post by: Glen Koehler on July 30, 2019, 08:39:26 PM
"Sodium Flerovium"
   Could be a spell from Hogwarts to desalinate seawater.
Title: Re: The caa-greenland mega crack
Post by: pearscot on July 30, 2019, 09:24:44 PM
According to the 7/30 imagery, it appears as though (within reason and for hypothetical purposes) save for one section, it is almost possible to sail around Greenland. I'm not sure if I've ever known this to be possible. Depending on how July unfolds, I wonder if this will completely open up. I'm inclined to say it is, given the fact that the crack continues to expand north and the open water will be absorbing more heat. Either way, this is the single most notable formation of this season.

Title: Re: The caa-greenland mega crack
Post by: aslan on July 31, 2019, 01:20:12 PM
It was already note in the melt season topic, but the paleoclimatology yield some interesting results regarding Greenland beaches :

https://s3.amazonaws.com/academia.edu.documents/39706551/A_10000-Year_Record_of_Arctic_Ocean_Sea-20151105-20427-ypl12t.pdf?response-content-disposition=inline%3B%20filename%3DA_10_000-Year_Record_of_Arctic_Ocean_Sea.pdf&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAIWOWYYGZ2Y53UL3A%2F20190731%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20190731T103208Z&X-Amz-Expires=3600&X-Amz-SignedHeaders=host&X-Amz-Signature=432ae45252627a5e521862c4450140b2ac01590c2e9659657457cc992e700760

I know it is sometimes difficult to be a weather man, but some definitive sentences are not going to pass the test of time : "and the ocean bordering North Greenland is expected to be the very last area to become ice-free in summer (2–4). "
Well, it is not looking quite likely now...

Beches are also found on the northwestern coast of Greenland, along the Smith Sound -wich is clear of ice now also- : http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.474.336&rep=rep1&type=pdf

Differents results are found elsewhere also : https://courses.seas.harvard.edu/climate/pdf/DeVernaletal2005PA001157.pdf

Ossifrage had some good insights about this subject, saying that the last bit of sea ice would probably be found more to the west, near the northern border of Canadian Archipelago. This can also have consequences for glaciers which are still buttstressed by sea ice : https://www.cambridge.org/core/services/aop-cambridge-core/content/view/5E27A9E9493AC5A9FEE361A4248AF8FF/S0260305500264549a.pdf/div-class-title-sea-ice-and-the-stability-of-north-and-northeast-greenland-floating-glaciers-div.pdf
The pack being fully detached from land is also bringing new questions. If the ice is more mobile, this can have effect on wind stress, currents, sea ice movements, etc. Can it also means that the pack can break in multiple parts ?
Title: Re: The caa-greenland mega crack
Post by: jdallen on August 01, 2019, 01:06:44 AM
Aslan - on the topic of benches, the crack actually offers an explanation that doesn't require a full melt out of the basin.  Factor in post melt elastic rebound and you have a working theory for how they got there.
Title: Re: The caa-greenland mega crack
Post by: binntho on August 01, 2019, 04:40:06 AM
Aslan - on the topic of benches, the crack actually offers an explanation that doesn't require a full melt out of the basin.  Factor in post melt elastic rebound and you have a working theory for how they got there.
I'm a bit suspicious here - I don't think a crack of 10 to 20 km, even occurring every year, can explain beach formation. Waves inshore would be very small and insignificant, espcecally since the crack seems to form mainly when offshore winds are strong and persistent.

The beach ridges described in the literature above seem quite substantial, indicating a large wave fetch in onshore winds.
Title: Re: The caa-greenland mega crack
Post by: jdallen on August 01, 2019, 07:11:59 AM
Aslan - on the topic of benches, the crack actually offers an explanation that doesn't require a full melt out of the basin.  Factor in post melt elastic rebound and you have a working theory for how they got there.
I'm a bit suspicious here - I don't think a crack of 10 to 20 km, even occurring every year, can explain beach formation. Waves inshore would be very small and insignificant, espcecally since the crack seems to form mainly when offshore winds are strong and persistent.

The beach ridges described in the literature above seem quite substantial, indicating a large wave fetch in onshore winds.
Agree 10-20 is not sufficient.  100-200 would be. 

Also consider, what are those benches cut in? Bedrock or sediment?  If sediment, it could have been frozen; we've seen how even modest surf has been chewing up permafrost along the Alaskan coast.

Like I said though, its the core of a hypothesis, which could be tested.
Title: Re: The caa-greenland mega crack
Post by: binntho on August 01, 2019, 07:16:52 AM
The paper seems to be talking about beach ridging, not benching. Ridging requires a fair degree of sand and gravel being moved by wave action and is a later stage than erosion of bedrock cliffs. Although sand and gravel from alluvial fans might be the source, rather than wave erosion of bedrock.
Title: Re: The caa-greenland mega crack
Post by: binntho on August 01, 2019, 08:12:49 AM
Agree 10-20 is not sufficient.  100-200 would be. 
The shortest distance between Svalbard and Greenland is 300 km, the Lincoln sea is about 200 km wide in the middle, and the distance from Greenland to the geographic North Pole is just over 400 km.

The present crack is 10 to 20 km wide, a 100-200 km wide crack wouldn't be a crack, would it? Difficult to see what the Arctic would look like with that much open water north of Greenland, I'd guess it would be extremely shortlived, either closing up or rapidly on the way to a BOE.
Title: Re: The caa-greenland mega crack
Post by: aslan on August 01, 2019, 09:29:15 AM
Yeah, I am not sure if I was clear in my last message but a crack of 10 - 20 km would not be enough for a beach. Of course we are probably not yet to the same situation than during Holocene. But it is starting to become really significant. Locally ocean is open over 50 km, excepted for small floes here and there. And, despite the title, it is probably not a "pure" crack. I mean, it is wind driven, but there is definitively some melt ongoing.  For example fjord Frederik Hyde is fully open since the 29th, with some melting, and now around the coast and Kap Ole Chiewitz, Kap Bridgemann, Kap etc... ocean is fully open over 30 - 40 km at least, save for small floes here and there. And around Kap Prins Knud etc... ( https://books.google.fr/books?id=uXwXL966F1cC&pg=PA261&lpg=PA261&dq=prinsesse+ingeborg+halve&source=bl&ots=JqhIF-Fsf5&sig=ACfU3U30-2i_yFBKmiH-tZT2ME0rwwm5VA&hl=fr&sa=X&ved=2ahUKEwjQseTql-HjAhV95eAKHXK1CQYQ6AEwDHoECAgQAQ#v=onepage&q=prinsesse%20ingeborg%20halve&f=false ) and somewhere in this corner of Greenland, ocean is even more open and exposed to Atlantic. And if there is still a ribbon of floes to the east, south of 80°N the Greenland sea is not really closed. And we have still at least one month to go before the end of melt season. This is not looking yet like Holocene, but there is definitively some tentative ongoing. And it is not looking like we will need a BOE for beach ridging over this caps.
Title: Re: The caa-greenland mega crack
Post by: binntho on August 01, 2019, 10:23:45 AM
And it is not looking like we will need a BOE for beach ridging over this caps.

But I think we do - I don't think there are any realistic scenarios where you can have so much open ocean north of Greenland / CAA with continuous incoming wave action for long enough periods without what is effectively a BOE.

The "crack" or whatever we should call it is too narrow, too shortlived, and most importantly, it is dependent on offshore winds so there will be no long-fetch waves capable of creating beach ridges.
Title: Re: The caa-greenland mega crack
Post by: gerontocrat on August 01, 2019, 12:30:04 PM
And it is not looking like we will need a BOE for beach ridging over this caps.

But I think we do - I don't think there are any realistic scenarios where you can have so much open ocean north of Greenland / CAA with continuous incoming wave action for long enough periods without what is effectively a BOE.

The "crack" or whatever we should call it is too narrow, too shortlived, and most importantly, it is dependent on offshore winds so there will be no long-fetch waves capable of creating beach ridges.
The crack is wider going east to the open water NE of Greenland.
How wide can this crack get and for how long can it persist?

GFS says moderate southerly winds for the next 5 days at least, while that Greenland high - extending north and east as far as Svalbard and even FJL- is looking rather permanent.

Mere speculation - but there is always a chance that the rules are changing. Mind you, that still means not much chance of  beach ridges as it is the offshore winds making the crack wider, and wider, and wider?
Title: Re: The caa-greenland mega crack
Post by: misfratz on August 01, 2019, 02:30:57 PM
According to the 7/30 imagery, it appears as though (within reason and for hypothetical purposes) save for one section, it is almost possible to sail around Greenland. I'm not sure if I've ever known this to be possible. Depending on how July unfolds, I wonder if this will completely open up. I'm inclined to say it is, given the fact that the crack continues to expand north and the open water will be absorbing more heat. Either way, this is the single most notable formation of this season.
The next step, which also seems to be closer than I can remember seeing it, would be for the main body of remaining Arctic Sea Ice to completely detach from any coastal land, so that it would be possible to circumnavigate the sea ice, without also circumnavigating land.
Title: Re: The caa-greenland mega crack
Post by: aslan on August 01, 2019, 03:49:19 PM
Sea state is the sum of wind waves and sweel. And swell from Atlantic can be quite long even in summer. If swell from Atlantic can reach Greenland coast -and this is almost the case now-, you don't need a great fetch.
Title: Re: The caa-greenland mega crack
Post by: pearscot on August 02, 2019, 01:22:37 AM
I had a spare moment at work and made this hella ghetto analysis of the crack above Greenland, it's over 7,202 square miles.

edit: I feel like that value is just wayyyy too large, but then again Greenland is huge so I don't know. If anyone thinks it is wrong, please let me know.

Title: Re: The caa-greenland mega crack
Post by: be cause on August 02, 2019, 01:43:21 AM
Pearscot .. is that area or extent ? b.c.
Title: Re: The caa-greenland mega crack
Post by: philopek on August 02, 2019, 01:55:54 AM
Pearscot .. is that area or extent ? b.c.

I think pearscot meant the open water that is neither area nor extent but open water.

Hope that I'm not wrong but cant's see another meaning at the moment ;)
Title: Re: The caa-greenland mega crack
Post by: petm on August 02, 2019, 02:01:09 AM
7k sq. mi. looks about right to me for the Greenland segment (>300 x 20 mi).
Title: Re: The caa-greenland mega crack
Post by: pearscot on August 02, 2019, 02:05:12 AM
Pearscot .. is that area or extent ? b.c.

I think pearscot meant the open water that is neither area nor extent but open water.

Hope that I'm not wrong but cant's see another meaning at the moment ;)

yes, my bad for any confusion - I just calculated the area in square miles for open water in that section above Greeland based on a polygon I created from a screenshot which I georeferenced.
Title: Re: The caa-greenland mega crack
Post by: be cause on August 02, 2019, 02:06:36 AM
sorry philopek .. it was an attempt at humour .. b.c.
Title: Re: The caa-greenland mega crack
Post by: philopek on August 02, 2019, 02:22:09 AM
sorry philopek .. it was an attempt at humour .. b.c.

That's the risk always ;)

Recommending to hint at least a tiny bit, else it's kind of roulette and since I'm luckily in love for decades I generally have bad luck with gambling ;) ;) ;)

[JK]
 

Title: Re: The caa-greenland mega crack
Post by: interstitial on August 02, 2019, 11:38:45 PM
Pearscot .. is that area or extent ? b.c.
add emoticon :)
Title: Re: The caa-greenland mega crack
Post by: aslan on September 03, 2019, 06:42:42 AM
This topic has drowned into the abyss of this forum, but the mega crack is still here and alive. And there is still sign of melt going on. To justify, Kap Moris Jesup hit 10.3°C the last day of August, a record for this time of year. And to the the North of Ellesmere, the Nares strait export has lead to a big, big hole. Fortunately the season is ending.
Title: Re: The caa-greenland mega crack
Post by: blumenkraft on September 03, 2019, 06:48:40 AM
Aslan, the polynya in Lincoln is not caused due to export through Nares. It's caused by winds blowing north. No ice was exported through Nares for months.

Check this post for a GIF showing it. >> https://forum.arctic-sea-ice.net/index.php/topic,176.msg224602.html#msg224602
Title: Re: The caa-greenland mega crack
Post by: binntho on September 03, 2019, 07:04:07 AM
Aslan, the polynya in Lincoln is not caused due to export through Nares. It's caused by winds blowing north. No ice was exported through Nares for months.

Check this post for a GIF showing it. >> https://forum.arctic-sea-ice.net/index.php/topic,176.msg224602.html#msg224602

That actually looks very interesting, that "plume" of open water stretching into the Lincoln sea. Looking back on Worlwiew and Nullschool, one can see how a large area opens up when the intense cyclone over the Beaufort pulled warm air up over the CAA and particularly, one guesses, throught the Nares. The following animation shows the opening and impeding closure of the Lincoln open ocean area.

Requires a click
Title: Re: The caa-greenland mega crack
Post by: aslan on September 03, 2019, 07:17:06 AM
Yes, it was bad wording on my part, not reflecting what I was actually thinking. It was more like, there was a strong preconditioning earlier with the lack of blocking in Nares strait, and now winds have an easier job.
Title: Re: The caa-greenland mega crack
Post by: blumenkraft on September 03, 2019, 07:21:36 AM
No worries, Aslan. :)

I wonder why there is no export. In winter with closed sea ice, there is a strong current southward. In summer, when the ice is cracked and mushy, the current stops. Why is that? Is a homogeneous ice cap causing some kind of pressure or what?
Title: Re: The caa-greenland mega crack
Post by: P-maker on September 03, 2019, 07:53:50 AM
Blumenkraft,

Every year in the freezing season, the volume of the Arctic sea surface expands by roughly 10 percent (due to the fact that density of sea ice is lover than that of sea water). If everything (including air pressure and sea level) remains constant, something will have to give in. Thus, when it's freezing in the Arctic, we will most of the time have southbound flows in the various straits. When it's melting, the opposite (deeper) flows will dominate.

It may be possible for some clever guy to come up with a simple indicator based on these principles.

Please enjoy the southward flowing ice as long as you can...
Title: Re: The caa-greenland mega crack
Post by: aslan on September 03, 2019, 03:05:44 PM
Yes, the conditions are more suitable for ice export in Winter, mostly due to variation in sea surface elevation :

Our model results based on 26-years of simulation with monthly output demonstrate that SSH gradients (calculated between two points north and south of each passage, which are denoted with asterisks shown in Figure 12) do explain the annual peak volume fluxes (around March) through both Nares Strait (Figure 14a) and Lancaster Sound (Figure 14b). The volume flux anomalies and SSH gradient anomalies are also highly correlated. Volume flux anomalies through Nares Strait (Figure 15a) and anomalies of the SSH gradient (measured from the Lincoln Sea to Smith Sound) (Figure 15b) were highly correlated (R = 0.89). Volume flux anomalies through the mouth of Lancaster Sound (Figure 15c) and anomalies of the SSH gradient (measured between the Queen Elizabeth Islands and western Baffin Bay) (Figure 15d) were also highly correlated (correlation R = 0.85).

https://pdfs.semanticscholar.org/870a/ad3242a2f319c69031342c9cedfa291df51e.pdf
Title: Re: The caa-greenland mega crack
Post by: SteveMDFP on September 03, 2019, 03:38:01 PM
Blumenkraft,

Every year in the freezing season, the volume of the Arctic sea surface expands by roughly 10 percent (due to the fact that density of sea ice is lover than that of sea water). If everything (including air pressure and sea level) remains constant, something will have to give in. . . .

I don't think that's how the physics works.  Certainly Nares and Fram surface currents are more robustly southward in winter than summer.  But not, I think, because sea water is freezing.  Sea ice displaces its *weight* and not its volume. 

Just as the water level in a glass of ice water doesn't change as the ice melts, neither does it change if ice forms in the glass.  Thus winter freezing of sea water into sea ice doesn't create any net change in forces of flow (all other changes being equal, which they never are in actuality).

I don't have an explanation for the observed seasonal flow patterns, but I'm pretty sure volume of ice formation isn't it.
Title: Re: The caa-greenland mega crack
Post by: longwalks1 on September 03, 2019, 04:35:12 PM
For the Timothy McGeehan Wieslaw Maslowski
Evaluation and control mechanisms of volume and freshwater export through the Canadian Arctic Archipelago in a high‐resolution pan‐Arctic ice‐ocean model
 https://doi.org/10.1029/2011JC007261

Nice Find.  Here is a link to a pdf final copy.  I have too many pre-print papers myself that I have not updated on my computer
Title: Re: The caa-greenland mega crack
Post by: blumenkraft on September 03, 2019, 05:57:27 PM
@longwalks, @Steve, @aslan, @P-maker yeah, that's exactly the kind of discussion i wanted to kickstart! Thanks, guys for contributing.

That said, reading Longwalks linked paper, i realize i'm stupid. I looked for SST anomalies the whole time but only in the Arctic basin, never in Baffin bay. That's indeed a great hint.

Quote
Abstract
[1] This study examined the 1979–2004 volume and freshwater fluxes through the Canadian Arctic Archipelago (CAA) and into the Labrador Sea using a high resolution (∼9 km) coupled ice‐ocean model of the pan‐Arctic region to provide a reference, compare with limited observational estimates, and investigate control mechanisms of this exchange. The 26‐year mean volume and freshwater fluxes through Nares Strait were 0.77 Sv ± 0.17 Sv and 10.38 mSv ± 1.67 mSv respectively, while those through Lancaster Sound amounted to 0.76 Sv ± 0.12 Sv and 48.45 mSv ± 7.83 mSv respectively. The 26‐year mean volume and freshwater fluxes through Davis Strait were 1.55 Sv ± 0.29 Sv and 62.66 mSv ± 11.67 mSv while the modeled Fram Strait branch provided very little (∼2%) freshwater into the Labrador Sea compared to the total CAA input. Compared to available observations, the model provides reasonable volume and freshwater fluxes, as well as sea ice thickness and concentration in the CAA. In Nares Strait and Lancaster Sound, volume flux anomalies were controlled by the sea surface height (SSH) gradient anomalies along the straits and freshwater anomalies were highly correlated with the volume anomalies. At least half of the variance in the time series of SSH gradient anomaly was due to SSH anomalies in northern Baffin Bay. The West Greenland Current (WGC) exhibits seasonality, with cross shelf flow (into the Labrador Sea) peaking in January/February/March, while reducing the northward flow across eastern Davis Strait. We hypothesize that the eddy‐reduced northward flow of WGC results in the lower volume and SSH in Baffin Bay. This maximizes the SSH gradients between the Arctic Ocean and Baffin Bay, leading to maximum winter volume fluxes through Nares Strait and Lancaster Sound. Model limitations include the insufficient spatial resolution of atmospheric forcing (especially to account for the effects of local topography), the representation of river runoff into Hudson Bay and coastal buoyancy currents, low mobility of modeled ice, and incomplete depiction of ice arching. Many of these issues are expected to be resolved with increased model grid cell resolution, improved sea ice and ocean models and more realistic atmospheric forcing.
Title: Re: The caa-greenland mega crack
Post by: aslan on September 03, 2019, 09:47:01 PM
Yes thanks longwalks ;) If there is specfic interest for the Nare Strait, the work of A. Münchow is worth citing :

"The established flow of seawater from Pacific to Atlantic Oceans through the Arctic has been attributed to higher sea level in the Pacific (Wijffels et al. 1992), associated with the lower salinity of Pacific waters. Sea level in the Atlantic may be more than 0.5 m lower than in the Pacific and 0.1–0.3 m lower than in the Arctic (Muench 1971). More accurate estimates of steric forcing have yet to be determined, but it is probably safe to conclude that much of the drop in sea level between Arctic and Atlantic Ocean occurs along the 530-km length of Nares Strait, thereby providing the impetus for the fluxes that we have measured.'

https://journals.ametsoc.org/doi/full/10.1175/JPO2962.1

https://www.researchgate.net/publication/233704692_Ocean_current_observations_from_Nares_Strait_to_the_west_of_Greenland_Interannual_to_tidal_variability_and_forcing
Title: Re: The caa-greenland mega crack
Post by: Juan C. García on October 08, 2019, 02:34:42 PM
I am surprised that remnants of the caa-greenland mega crack are still there today. I wonder of the implications that it could have on the 2020 melting season. That is, could be possible to have more mobility of the older ice on 2020, if it is not strongly attached to land? It should be first-year ice what we will have on the mega crack.
Title: Re: The caa-greenland mega crack
Post by: kassy on October 08, 2019, 03:43:36 PM
The big question is if the mega crack will happen again next year and so on. The ice being young does not help but if the reason is changed currents (or weaknesses only recently showing) that will change the story for the future.

A much more mobile central ice pack can go anywhere in a bad year.
Title: Re: The caa-greenland mega crack
Post by: Juan C. García on October 09, 2019, 06:12:13 AM
The big question is if the mega crack will happen again next year and so on. The ice being young does not help but if the reason is changed currents (or weaknesses only recently showing) that will change the story for the future.

A much more mobile central ice pack can go anywhere in a bad year.
It also happened on 2018. Maybe not as big on CAA, but surely important north of Greenland.
Title: Re: The caa-greenland mega crack
Post by: uniquorn on October 09, 2019, 01:06:57 PM
Today's worldview viirs brightness temperature, band15, night with yesterday's amsr2-uhh inset.
https://go.nasa.gov/2MvVvvg
click for full resolution
Title: Re: The caa-greenland mega crack
Post by: Pmt111500 on October 10, 2019, 11:34:47 AM
The big question is if the mega crack will happen again next year and so on. The ice being young does not help but if the reason is changed currents (or weaknesses only recently showing) that will change the story for the future.

A much more mobile central ice pack can go anywhere in a bad year.
It also happened on 2018. Maybe not as big on CAA, but surely important north of Greenland.

At this point in time for me it is not anymore a question of will it happen, but will it not happen on some years. This is essentially the same phenomenon that's common knowledge on other shores as well, the waves turn toward the shore by friction with the shore and the return current may take an unwary swimmer/diver pretty far out. As the ice is 90% underwater, somewhere near the shore the outbound forces exceed the cohesion of the ice and the crack develops. Strong winds and currents may counteract, of course, but I'd be surprised if this does not become a regular feature of the Arctic now.
Title: Re: The caa-greenland mega crack
Post by: philopek on October 10, 2019, 04:40:51 PM
<SNIPPED>unwary swimmer/diver pretty far out. As the ice is 90% underwater, somewhere near the shore the outbound forces exceed the cohesion of the ice and the crack develops. Strong winds and currents may counteract, of course, but I'd be surprised if this does not become a regular feature of the Arctic now.

Good point for consideration.

I assume you mean something of the linked kind.

https://en.wikipedia.org/wiki/Rip_current
Title: Re: The caa-greenland mega crack
Post by: Pmt111500 on October 10, 2019, 05:32:44 PM
<SNIPPED>unwary swimmer/diver pretty far out. As the ice is 90% underwater, somewhere near the shore the outbound forces exceed the cohesion of the ice and the crack develops. Strong winds and currents may counteract, of course, but I'd be surprised if this does not become a regular feature of the Arctic now.

Good point for consideration.

I assume you mean something of the linked kind.

https://en.wikipedia.org/wiki/Rip_current

Yep, didn't have the english word for it.

With ice over water they're not strong but still there.
Title: Re: The caa-greenland mega crack
Post by: Shared Humanity on October 11, 2019, 04:28:34 PM
Local winds and shoreline wave behavior certainly could contribute to cracks along the CAA and the north coast of Greenland but far more important are the ocean currents that have always been in play. Arctic sea ice has always either migrated towards the Beaufort or towards the Fram. Ice east of the Lincoln Sea will eventually find its way through the Fram while ice west of the the Lincoln Sea is drawn into the Beaufort. When the ice in this area of the Arctic Ocean was made up of thick (5 to 10 meters) rafts of MYI, these currents struggled to cause the ice to lift off and move. This thick ice no linger exists here. We have a melange of small MYI ice flows no more than 4 meters thick and thin 1st year ice that is highly mobile. I see no process that will cause thick MYI ice to reform so we should expect this lifting off behavior to persist and worsen.
Title: Re: The caa-greenland mega crack
Post by: uniquorn on October 31, 2019, 04:40:30 PM
uni-hamburg amsr2-uhh update of the caa/cab crack, sep21-oct30
Title: Re: The caa-greenland mega crack
Post by: RoxTheGeologist on October 31, 2019, 05:32:13 PM
Blumenkraft,

Every year in the freezing season, the volume of the Arctic sea surface expands by roughly 10 percent (due to the fact that density of sea ice is lover than that of sea water). If everything (including air pressure and sea level) remains constant, something will have to give in. . . .

I don't think that's how the physics works.  Certainly Nares and Fram surface currents are more robustly southward in winter than summer.  But not, I think, because sea water is freezing.  Sea ice displaces its *weight* and not its volume. 

Just as the water level in a glass of ice water doesn't change as the ice melts, neither does it change if ice forms in the glass.  Thus winter freezing of sea water into sea ice doesn't create any net change in forces of flow (all other changes being equal, which they never are in actuality).

I don't have an explanation for the observed seasonal flow patterns, but I'm pretty sure volume of ice formation isn't it.

If you put a piece of ice in a glass of saltwater, the freshwater from the ice flows to cover the saltwater. Freshwater/ice from the arctic is less dense and therefore there is an elevation difference. Hydrostatic stress is the same but the diviatoric stress makes the water flow (as its incompressible). its a long time since I did any continuum mechanics so my explanation may be wonky. Water flows downhill?
Title: Re: The caa-greenland mega crack
Post by: uniquorn on October 31, 2019, 08:42:21 PM
Today's worldview viirs brightness temperature band15, night. 'Heat' escaping from the cracks at ~-2C. Cloud forming over the Lincoln sea at some distance from the Greenland coast. Click for full resolution.
https://go.nasa.gov/2WvntvO
Title: Re: The caa-greenland mega crack
Post by: uniquorn on November 02, 2019, 08:48:39 PM
Floes tearing across the PGAS, recently fast ice lifting off from Ellesmere.
https://go.nasa.gov/32a0hoj, oct31-nov2   click to run
Title: Re: The caa-greenland mega crack
Post by: HapHazard on November 03, 2019, 01:57:41 AM
So how "normal" is this? Or is "the crack" now a normal feature?

For a few years now, I've had a hunch that if the polar vortex breaks down enough (plus the "right" weather for a week or so), the entire pack may pull away from the CAA in the summer and thus accelerate melt > new record minimum by a fair margin. I find this quite concerning, as with [current?] preconditioning it could be quite abrupt.

?
Title: Re: The caa-greenland mega crack
Post by: uniquorn on November 03, 2019, 03:08:41 PM
uni-hamburg amsr2-uhh, north CAA/Greenland, 2012-2018 (some missing data)
Title: Re: The caa-greenland mega crack
Post by: HapHazard on November 04, 2019, 08:31:50 PM
So, it appears to have been "normal but intermittent" but this year it's has been more akin to a permanent feature.
Title: Re: The caa-greenland mega crack
Post by: uniquorn on November 04, 2019, 11:22:56 PM
Nares export and more lift off from the west greenland coast. Looks set to continue with the current forecast.
https://go.nasa.gov/2rd2Qcm , oct30-nov4, click to run
Title: Re: The caa-greenland mega crack
Post by: uniquorn on November 07, 2019, 10:56:28 PM
Ice north west of Ellesmere looking quite ragged today.
https://go.nasa.gov/2CkcoV8 , nov1-7 click to run
Title: Re: The caa-greenland mega crack
Post by: uniquorn on November 12, 2019, 04:24:31 PM
More lift off from ellesmere today and quite a big pull back in the Peary channel. Lincoln sea starting to look 'normal'.
https://go.nasa.gov/2KgFdGp , nov8-12 click to run
full moon?
Title: Re: The caa-greenland mega crack
Post by: blumenkraft on November 12, 2019, 04:45:32 PM
full moon?

I increasingly think this is a main variable.
Title: Re: The caa-greenland mega crack
Post by: uniquorn on November 24, 2019, 10:50:30 AM
Some lift off to feed the Beaufort arc
Title: Re: The caa-greenland mega crack
Post by: uniquorn on November 26, 2019, 04:18:12 PM
crack comparison, Peary-PGAS, nov26 2017-2019   https://go.nasa.gov/2DoNgwR
map courtesy of ossifrage
Title: Re: The caa-greenland mega crack
Post by: uniquorn on December 06, 2019, 01:38:35 PM
significant shear, https://go.nasa.gov/38eGIiQ   cffr
Title: Re: The caa-greenland mega crack
Post by: uniquorn on December 06, 2019, 07:41:49 PM
Fast ice still lifting off the mclure strait, https://go.nasa.gov/38fCYxy
Title: Re: The caa-greenland mega crack
Post by: uniquorn on December 08, 2019, 11:31:22 AM
Lincoln sea still mobile. Lift off again from NW Greenland coast.
https://go.nasa.gov/2PsDJe3  dec1-8 ctr
Title: Re: The caa-greenland mega crack
Post by: uniquorn on December 30, 2019, 08:36:15 PM
lift off east of ellef ringnes.
https://go.nasa.gov/39kMPTj  dec26-30,   ctr
Title: Re: The caa-greenland mega crack
Post by: uniquorn on March 16, 2020, 11:19:00 PM
looking at #67, 2017 and 2018 had a short lift off early in the season
Title: Re: The caa-greenland mega crack
Post by: uniquorn on April 07, 2020, 01:25:43 AM
https://go.nasa.gov/2JKinq2 , not very fast ice, caa, apr5-6.  ctr
Title: Re: The caa-greenland mega crack
Post by: uniquorn on April 22, 2020, 12:14:52 AM
mega micro cracks, caa north greenland, apr21.  https://go.nasa.gov/2VIPG2i
Title: Re: The caa-greenland mega crack
Post by: uniquorn on April 23, 2020, 04:37:34 PM
Borrowed these worldview settings from A-team https://go.nasa.gov/3eEzxDP
Title: Re: The caa-greenland mega crack
Post by: ajouis on April 27, 2020, 07:00:08 PM
Courtesy of Pearscott
https://forum.arctic-sea-ice.net/index.php?action=dlattach;topic=3017.0;attach=147560
Looks like ihe crack is back on the caa side
Title: Re: The caa-greenland mega crack
Post by: pearscot on April 28, 2020, 05:58:49 PM
So I just checked that same area this morning and I'm just amazed at what I'm seeing right now. First and foremost is how clear it has been in that entire region. It's usually extremely cloudy there, but this has been the longest stretch without thicc clouds I have seen in the arctic since I've been following it. I'm not sure how these conditions will play out the rest of the year, but I can't imagine it being "good."

Either way, over the course of the last 24 hours it looks like drift has picked up significantly with a larger and more fragmented gap beginning to appear. After looking at the same date going back to 2014, nothing quite compares. Granted, there does appear to be a constant eastern/northeastern flow of ice, with cracks, but what makes this year unique is the already substantial gap and the amount of fractures within the central pack itself.

Feel free to take a look for yourselves, but my initial feeling is that this entire crack will emerge again this year. 
Title: Re: The caa-greenland mega crack
Post by: uniquorn on May 14, 2020, 10:40:14 PM
https://go.nasa.gov/2Lswlh5, north ellesmere, may13-14. click to run
Title: Re: The caa-greenland mega crack
Post by: pearscot on May 15, 2020, 02:27:47 AM
Wow! Thanks for posting that! I'm amazed at how much can change in such a short period of time. As soon as the clouds clear from north Greenland I'm going to do some detailed comparisons
Title: Re: The caa-greenland mega crack
Post by: uniquorn on May 16, 2020, 10:11:03 AM
uni-hamburg amsr2-uhh, north CAA, may4-15. click to run.
I think that in previous years there is usually a more progressive lift off from Beaufort to Lincoln.
edit:2013 lifted off from Beaufort to PGAS around this time of year
2017 all the way to Lincoln sea
2019 to PGAS

Interesting to compare fracture locations to piomas thickness

(https://forum.arctic-sea-ice.net/index.php?action=dlattach;topic=119.0;attach=148090;image)

added overlay onto gmrt bathymetry (https://www.gmrt.org/GMRTMapTool/np/)   click to run
Title: Re: The caa-greenland mega crack
Post by: uniquorn on May 19, 2020, 11:36:49 PM
Worldview, terra modis, https://go.nasa.gov/36lOYNu, may19
Greyscale, linear contrast to bring out floe character (shown inset).
click for full resolution.
Title: Re: The caa-greenland mega crack
Post by: uniquorn on May 20, 2020, 12:38:24 PM
S1B from https://www.polarview.aq/arctic yesterday. It looks like there is some refreeze though it could be waves, temperatures at alert were around -7C, nullschool gfs were higher at ~-2C over the crack.
cffr
Title: Re: The caa-greenland mega crack
Post by: pearscot on May 20, 2020, 05:58:56 PM
While this crack is certainly not all that wide, it certainly exists and remains after the cold weather and storm which has been in the region for a while.

Part of me wonders as the pack gains mobility and rotates more, if the Fram Strait acts like a peeler and shaves off ice as the pack more broadly spins in conjunction with southern winds in that region?

Either way, it was just a little more clear today and I found this most recent artifact noteworthy:


Title: Re: The caa-greenland mega crack
Post by: blumenkraft on May 20, 2020, 06:31:30 PM
... could be waves ...

If it is indeed one of those two, my bet is on waves. It could be fog too IMHO.

Title: Re: The caa-greenland mega crack
Post by: pearscot on May 21, 2020, 09:47:36 PM
^^ you are correct, that was just fog and as of today the water remains open.

Sometimes a picture is worth a thousand words, so I won't say much.

Imagine what this will look like in 1 month(!)
Title: Re: The caa-greenland mega crack
Post by: Paul on May 21, 2020, 10:20:27 PM
^^ you are correct, that was just fog and as of today the water remains open.

Sometimes a picture is worth a thousand words, so I won't say much.

Imagine what this will look like in 1 month(!)

It's an interesting hole but in terms of what it may look like in 1 months time then I would not be surprised if its covered with ice again, its not temperature related why the hole is there, its down to the fact we actually got some fast(or at least quite resilient) ice blocking the nares strait so basically when the winds was blowing in the right direction, the looser ice seperated itself from the fast ice hence the hole.
Title: Re: The caa-greenland mega crack
Post by: pearscot on May 21, 2020, 10:57:24 PM
^^ you are correct, that was just fog and as of today the water remains open.

Sometimes a picture is worth a thousand words, so I won't say much.

Imagine what this will look like in 1 month(!)

It's an interesting hole but in terms of what it may look like in 1 months time then I would not be surprised if its covered with ice again, its not temperature related why the hole is there, its down to the fact we actually got some fast(or at least quite resilient) ice blocking the nares strait so basically when the winds was blowing in the right direction, the looser ice seperated itself from the fast ice hence the hole.

I meant the entire crack, not that singular open area. From my observations, the pack is becoming more and more mobile and more susceptible to spin in the gyre. I'm sure that one may close and another can open again. If you look at some animations or use the worldview video feature, you can see how dynamic the whole area is (which is surprising this early in the melt season)
Title: Re: The caa-greenland mega crack
Post by: uniquorn on May 30, 2020, 05:25:21 PM
The polynya north of ellesmere, uni-hamburg amsr2uhh, may10-29.
Title: Re: The caa-greenland mega crack
Post by: uniquorn on May 31, 2020, 08:55:44 PM
https://go.nasa.gov/2yPoXd3, Nth ellesmere polynya, may13-31.
Worryingly persistent.
click to play
Title: Re: The caa-greenland mega crack
Post by: johnm33 on May 31, 2020, 09:23:32 PM
Atl. water penetration getting caught up in the submarine channel (https://geos.polarview.aq/geoserver/gwc/service/wms?LAYERS=gwcPolarviewCoastArctic10Grat&FORMAT=image%2Fpng&TRANSPARENT=TRUE&SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&STYLES=&SRS=EPSG%3A3413&BBOX=-1640001.814399,599996.97600163,-520002.41919869,1719996.371202&WIDTH=200&HEIGHT=200) and flowing towards the coast? That would fit with what seems to be melt/reduced salinity west of CAA on Hycoms model.
Title: Re: The caa-greenland mega crack
Post by: uniquorn on June 11, 2020, 02:00:05 PM
Almost gone but not quite forgotten.
Title: Re: The caa-greenland mega crack
Post by: uniquorn on June 15, 2020, 10:18:43 PM
Worldview aqua modis, Mclure-PGAS, jun15, some clearer weather over possible thicker ice (piomas) (https://forum.arctic-sea-ice.net/index.php/topic,119.msg267003.html#msg267003)
Title: Re: The caa-greenland mega crack
Post by: JayW on June 27, 2020, 06:03:32 PM
https://rammb-slider.cira.colostate.edu/?sat=jpss&z=4&im=12&ts=1&st=0&et=0&speed=130&motion=loop&map=1&lat=0&opacity%5B0%5D=1&hidden%5B0%5D=0&pause=20200627010753&slider=-1&hide_controls=1&mouse_draw=0&follow_feature=0&follow_hide=0&s=rammb-slider&sec=northern_hemisphere&p%5B0%5D=band_i02&x=17979.02734375&y=16730.888671875

Nansen sound and it's very dark ice in the lower right.

Click to run
Title: Re: The caa-greenland mega crack
Post by: pearscot on June 27, 2020, 10:30:23 PM
Today's the first real clear day above Greenland and the CAA. It's been warm in that entire region and it appears as though this crack will continue to grow as the pack melts more and can spin more freely in the gyre.

Title: Re: The caa-greenland mega crack
Post by: pearscot on June 28, 2020, 12:51:36 AM
But wait, there's more. Now that the rest of the imagery was cached from Worldview you can see the extent to which the entire pack is both mobile and fractured

Title: Re: The caa-greenland mega crack
Post by: be cause on July 01, 2020, 01:16:36 AM
There was a lift-off of the ice East of Alert around to the Nares enterance . It can be seen best on Worldview atm as you zoom in @ 50km/50ml a.. as you zoom closer the frame changes to showing cracking but the departure from shore is no longer clear .
  Lincoln is an amazing zone of shear , disintergration and melting of what looked like the safest ice in the Arctic only 2 weeks ago .
         +++             It's now gettin' ground up like salt in situ !  b.c.
Title: Re: The caa-greenland mega crack
Post by: JayW on July 01, 2020, 01:59:30 AM
There was a lift-off of the ice East of Alert around to the Nares enterance . It can be seen best on Worldview atm as you zoom in @ 50km/50ml a.. as you zoom closer the frame changes to showing cracking but the departure from shore is no longer clear .
  Lincoln is an amazing zone of shear , disintergration and melting of what looked like the safest ice in the Arctic only 2 weeks ago .
         +++             It's now gettin' ground up like salt in situ !  b.c.
As it happened. Click to run.
Title: Re: The caa-greenland mega crack
Post by: be cause on July 01, 2020, 02:05:46 AM
Thanks JayW .. the moment has been lost now from Worldview .. but you have captured it beautifully .. bc
Title: Re: The caa-greenland mega crack
Post by: JayW on July 01, 2020, 10:17:05 AM
Thanks JayW .. the moment has been lost now from Worldview .. but you have captured it beautifully .. bc
There is also a rapid and significant darkening of the ice picked up by the visible bands, likely due to warming air descending of the landmass and blowing over the ice.  Shows up in AMSR2.
Title: Re: The caa-greenland mega crack
Post by: blumenkraft on July 01, 2020, 10:19:47 AM
RAMMB stuck again?
Title: Re: The caa-greenland mega crack
Post by: JayW on July 01, 2020, 10:28:00 AM
RAMMB stuck again?
Appears that way, I fired over a email just now.  Hopefully it helps.
Title: Re: The caa-greenland mega crack
Post by: blumenkraft on July 01, 2020, 10:33:12 AM
Thanks, mate! 👍🏽
Title: Re: The caa-greenland mega crack
Post by: uniquorn on July 12, 2020, 09:22:05 PM
The crack must have gone  ;)
Title: Re: The caa-greenland mega crack
Post by: uniquorn on July 13, 2020, 01:22:40 AM
or not    https://go.nasa.gov/3gKlrku
Title: Re: The caa-greenland mega crack
Post by: blumenkraft on July 13, 2020, 08:32:38 AM
The crack must have gone  ;)

Yes, a polynya has replaced it.  :-[
Title: Re: The caa-greenland mega crack
Post by: Pagophilus on July 14, 2020, 06:50:33 PM
Thanks for pointing me here, pearscot.  You and I have similar replies on the melting thread.  Here are the images which are particularly clear from July 13 Worldview.  First time I had noticed it opening significantly off Greenland at this time of year.    Ominous stuff.    :o

Any names for this beast ... the Kraken, or Cracken?   :-\
Title: Re: The caa-greenland mega crack
Post by: oren on July 14, 2020, 07:35:57 PM
It's all part of the crazy movement and compaction of ice induced by the unending HP/anti-cyclone in the CAB. At least it's better than if the thick ice in the Lincoln Sea and above the CAA moved the other way, towards Fram and oblivion.
Title: Re: The caa-greenland mega crack
Post by: pearscot on July 14, 2020, 07:44:54 PM
That is just a huge area of open water exposed to the sun. Granted that water is about as cold as it can get and still be liquid, but it will most certainly be soaking up energy. I keep wondering if some critical level will be reached where the ice becomes so detached from the land that it can freely spin in the gyre - my concern with that is the warm peripheral water will be able to continually melt the uneven edges. I need to do some calculations, but wow this is already a fairly large region which would normally send most of that energy right back.

Title: Re: The caa-greenland mega crack
Post by: oren on July 14, 2020, 07:49:23 PM
As long as ice area isn't crashing, energy soaked here will be reflected somewhere else. And the 2-3m ice in the Lincoln Sea can easily overcome the enrrgy soaked in a few days or even weeks by this crack. I wouldn't worry too much about this aspect.
The pack becoming more mobile could be a concern. Upwelling of warm salty water could also have an effecy. And dispersion of ice into the Siberian seas will also lead to quick demise.
Title: Re: The caa-greenland mega crack
Post by: CraigsIsland on July 14, 2020, 08:37:19 PM
But wait, there's more. Now that the rest of the imagery was cached from Worldview you can see the extent to which the entire pack is both mobile and fractured

Interesting new feature with Pikachu - looks rather large.
Title: Re: The caa-greenland mega crack
Post by: pearscot on July 14, 2020, 08:57:00 PM
But wait, there's more. Now that the rest of the imagery was cached from Worldview you can see the extent to which the entire pack is both mobile and fractured

Interesting new feature with Pikachu - looks rather large.

The surprised Pikachu face is how I felt when I made that. At a loss for words and just like: is this reality right now??
Title: Re: The caa-greenland mega crack
Post by: blumenkraft on July 14, 2020, 09:23:00 PM
The surprised Pikachu face

Wait, one does not simply bring up Pikachu face without making it a propper meme!
Title: Re: The caa-greenland mega crack
Post by: CraigsIsland on July 14, 2020, 09:33:12 PM
But wait, there's more. Now that the rest of the imagery was cached from Worldview you can see the extent to which the entire pack is both mobile and fractured

Interesting new feature with Pikachu - looks rather large.

The surprised Pikachu face is how I felt when I made that. At a loss for words and just like: is this reality right now??

Pretty accurate reaction to have. It's early in the season for that feature to open up.

Year in, year out..
(https://media.giphy.com/media/tpwwhv1BLd31e/giphy.gif)
Title: Re: The caa-greenland mega crack
Post by: UCMiami on July 14, 2020, 11:02:01 PM
The crack north of greenland has widen by about 15 km in the last 24 hours on the western section of the attached image from WV and the elongated flow on the middle right of the image has moved west about 42 km in the same 24 hours (and turned) A lot of movement which has to be creating turbulence in the water.
Title: Re: The caa-greenland mega crack
Post by: uniquorn on July 14, 2020, 11:59:43 PM
More fast ice breaking off Ellesmere Island and NE Greenland. Rammb has shown a lot of turbulence during open water events north of Greenland in the past.
Title: Re: The caa-greenland mega crack
Post by: JayW on July 15, 2020, 12:06:33 AM
RAMMB fully updating, for now.
Check out the little holes in the Sverdrup channel, the tides are already trying to enlarge the bigger one.
Needs click
Title: Re: The caa-greenland mega crack
Post by: uniquorn on July 15, 2020, 12:18:42 AM
Similar to last year, I think.
Maybe you can catch this.. click
The fast ice north of Princess Thyra Island lifted off between aqua and terra passes, jul14
Title: Re: The caa-greenland mega crack
Post by: pearscot on July 15, 2020, 12:26:21 AM
The surprised Pikachu face

Wait, one does not simply bring up Pikachu face without making it a propper meme!

LOL that made my day! Ha, that's exactly what I've been thinking whenever I fire up the ol' worldview to see the daily changes.
Title: Re: The caa-greenland mega crack
Post by: JayW on July 15, 2020, 12:54:38 AM
For uniquorn, these are all the images that were available.

Second is just east of Nansen sound.  Lots of areas breaking up the CAA

Both need clicks.
Title: Re: The caa-greenland mega crack
Post by: VeliAlbertKallio on July 15, 2020, 04:22:31 AM
It seems me clear that the usual footing on Russian side having been lost record early and lot, has had an impact for the sea ice footing of the American side. Back in 2006 I predicted (and repeated at my RSE VII presentation at "Arctic - Mirror of Life Symposium" 2007) that lop-sided Polar Sea Ice cap would emerge once sea ice's spatial extent diminishes. The smaller radius the central pack has, the more spatial dislodgement will emerge. Ultimately, the limit is how far winds and currents can push ice to one direction. This seems to be the case now, with also QE islands void filled by lose ice debris.

https://worldview.earthdata.nasa.gov/?v=-1428665.4368975572,-698424.6018564447,-691385.4368975572,-269880.60185644473&p=arctic

I do not know yet if my other RSE VII prediction that compacted ice packs would survive far more pounding than dispersed ones, has reality to it. If so, then we may end with large sea ice area of rotten ice. This kind of soft, honeycombed ice obviously is extremely sensitive to wind damage like GAC 2012. But in the absence of winds, and setting sun, we might end with extraordinary amount of poor quality ice by the autumn. Would the present setting enhance such long lasting stills until the fall and darkness?

But wait, there's more. Now that the rest of the imagery was cached from Worldview you can see the extent to which the entire pack is both mobile and fractured

Interesting new feature with Pikachu - looks rather large.

The surprised Pikachu face is how I felt when I made that. At a loss for words and just like: is this reality right now??
Title: Re: The caa-greenland mega crack
Post by: interstitial on July 15, 2020, 08:47:13 AM
Against the coast there is where all the thickest ice is. In years past I thought all it was doing is opening the crack and closing it. If it is seriously melting.....
Title: Re: The caa-greenland mega crack
Post by: uniquorn on July 15, 2020, 01:59:32 PM
For uniquorn, these are all the images that were available.
Second is just east of Nansen sound.  Lots of areas breaking up the CAA
No time stamps on wolrdview so rammb adds more info. Coastal winds at princess thyra island were 40km/h at 1000hPa, only 21km/h at Ellesmere Is. That both lift off's happened at the same time could just be coincidence. There wasn't a large tide at Alert.

edit: They are probably caused by melt further upstream which can be seen in both cases.
edit2: but 4 lift off's in 4 days?? (https://forum.arctic-sea-ice.net/index.php/topic,3017.msg274279.html#msg274279)
Title: Re: The caa-greenland mega crack
Post by: uniquorn on July 15, 2020, 02:53:20 PM
'crack' ice didn't really settle down fully till jan1, had a small lift off again around pgas on feb29, mar21 and 31, then apr28. A larger lift off started on may13. The most recent jun27.
uni-hamburg amsr2-uhh, caa-crack, sep21-jul14  (8.2MB)
Title: Re: The caa-greenland mega crack
Post by: JayW on July 17, 2020, 11:39:09 AM
North of Ellesmere.
Interesting little counter current there.
Title: Re: The caa-greenland mega crack
Post by: pearscot on July 17, 2020, 07:18:55 PM
Wow, I didn't realize just how quickly all the ice in the region was actually moving. The arctic is such a dynamic system in general!

it really is hard to imagine just how much a small change like that crack can make. Ice that would normally just be glued to the coast is now just gliding parallel to it.
Title: Re: The caa-greenland mega crack
Post by: uniquorn on July 19, 2020, 01:12:29 AM
Drift that requires an explanation
Title: Re: The caa-greenland mega crack
Post by: uniquorn on July 23, 2020, 12:11:45 AM
Clear day, big picture. https://go.nasa.gov/2ZRSZaB
Title: Re: The caa-greenland mega crack
Post by: pearscot on July 23, 2020, 06:56:33 AM
After watching this crack grow/morph all season, I'm growing increasingly convinced that soon the ice at the Western edge of Ellesmere Island  will eventually meet up with the North Canadian coastline as the Beaufort either melts out or spins more in the gyre.

Either way, the ice flow now possible into the Nares Strait (from what I've roughly measured on Worldview) is about 10km per day. I think if the ice were solid between Ellesmere and Greenland, the crack would extend all the way around Greenland's north coast.

All that said, I think the mega crack will continue to grow and I suspect will become a mini-Fram export. Plus, after 2019, I think it's becoming clear that this crack is becoming a new feature of the Arctic. It's kinda wild to think that some of the coastlines have probably not had water splash on them for maybe the last 100 years. I'd love to see really old satellite imagery of the arctic.
Title: Re: The caa-greenland mega crack
Post by: johnm33 on July 23, 2020, 01:57:06 PM
I think/guess the vortices which supplememented the wind action remain connected at depth, where they're [re]generated, bending over the shelf like a tornado. They in turn generate sub vortices which move up any channels they get formed in, the ridge pointing west from A.H.I./E.I. gap at 300m is too big to cross so the main action slips into the deep. Here the vortice will lose ground to the rotating frame but how much probably depends both on mass movements where it connects at it's base and on it's spin.
The surge which generated the vortices moves seperately pushing into the CAA, adding inertia, and Canada Basin bringing turbulence to Beaufort. With the low north of FJL we should see enhanced flow of Atl. waters towards Nares and beyond so further warming ++salinity of seas passing through CAA.
Title: Re: The caa-greenland mega crack
Post by: oren on July 23, 2020, 02:44:17 PM
A small hole in the ice appeared on the 17th at the top of Ellef Ringnes Island, and has grown since. Not sure if it will have time to join the rest of the crack.

https://worldview.earthdata.nasa.gov/?v=-1120252.1287857858,-613426.33462354,-923644.1287857859,-516146.33462354005&p=arctic&t=2020-07-21-T12%3A40%3A11Z&l=Reference_Features(hidden),Coastlines,Graticule(hidden),VIIRS_SNPP_CorrectedReflectance_BandsM11-I2-I1(hidden),VIIRS_SNPP_CorrectedReflectance_BandsM3-I3-M11(hidden),VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_Bands721(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,MODIS_Terra_CorrectedReflectance_Bands367(hidden),MODIS_Terra_CorrectedReflectance_Bands721(hidden) (https://worldview.earthdata.nasa.gov/?v=-1120252.1287857858,-613426.33462354,-923644.1287857859,-516146.33462354005&p=arctic&t=2020-07-21-T12%3A40%3A11Z&l=Reference_Features(hidden),Coastlines,Graticule(hidden),VIIRS_SNPP_CorrectedReflectance_BandsM11-I2-I1(hidden),VIIRS_SNPP_CorrectedReflectance_BandsM3-I3-M11(hidden),VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_Bands721(hidden),MODIS_Terra_CorrectedReflectance_TrueColor,MODIS_Terra_CorrectedReflectance_Bands367(hidden),MODIS_Terra_CorrectedReflectance_Bands721(hidden))
Title: Re: The caa-greenland mega crack
Post by: JayW on July 25, 2020, 12:03:08 AM
NW Greenland. Revisiting a feature from lat year. I included more of the opening in case there is interest in the motion there.  82 hours, kinda big sorry, did my best.
Click to bring to life.
Title: Re: The caa-greenland mega crack
Post by: pearscot on July 27, 2020, 12:08:53 AM
It continues to impress and I'l be interested in seeing what happens to the Atlantic side this coming week.
Title: Re: The caa-greenland mega crack
Post by: KenB on July 27, 2020, 04:54:40 PM
4 day (7/23-7/27) breakup off the northernmost tip of Greenland:

Title: Re: The caa-greenland mega crack
Post by: Pmt111500 on July 27, 2020, 05:30:35 PM
The weather forecast looks like the crack (gap) could easily become 100 km wide. Basing this on the vaguely remembered images of northern most melts on Baltic and storms moving ice floes from Finnish coast to Swedish coast...
Title: Re: The caa-greenland mega crack
Post by: JayW on July 28, 2020, 01:02:35 AM
Love watching these eddies.
Needs click.

Title: Re: The caa-greenland mega crack
Post by: Pmt111500 on July 28, 2020, 08:05:32 AM
Love watching these eddies.
Needs click.

Yep, tries to separate but the waves to the shore keep on twisting the flow of the floes.
Title: Re: The caa-greenland mega crack
Post by: uniquorn on July 29, 2020, 11:28:10 PM
Westward motion is slowing. That floe must have landed gently on the tip of Axel Heilberg.
jul19-29
Title: Re: The caa-greenland mega crack
Post by: uniquorn on July 29, 2020, 11:50:55 PM
amsr2-uhh view, jul21-28
Title: Re: The caa-greenland mega crack
Post by: KenB on July 30, 2020, 09:13:48 PM
Westward motion is slowing. That floe must have landed gently on the tip of Axel Heilberg.
jul19-29

The one shaped like a boat, I assume you mean?  I've been watching that, too.  It now seems like the island is taking a bit of a bite out of the floe, maybe not so gently. 

As nice as it is to have WorldView, what I'd like here is WorldHear, so I can find out what it sounds like for a 20km piece of ice to bounce into an even bigger rock.
Title: Re: The caa-greenland mega crack
Post by: Freegrass on August 12, 2020, 12:22:20 AM
The mega crack is opening up again.
Title: Re: The caa-greenland mega crack
Post by: glennbuck on August 12, 2020, 10:15:00 PM
The one shaped like a boat, I assume you mean?  I've been watching that, too.  It now seems like the island is taking a bit of a bite out of the floe, maybe not so gently. 

As nice as it is to have WorldView, what I'd like here is WorldHear, so I can find out what it sounds like for a 20km piece of ice to bounce into an even bigger rock.

This rare footage has gone on record as the largest glacier calving event ever captured on film, by the 2016 Guiness Book of World Records.

On May 28, 2008, Adam LeWinter and Director Jeff Orlowski filmed a historic breakup at the Ilulissat Glacier in Western Greenland.  The calving event lasted for 75 minutes and the glacier retreated a full mile across a calving face three miles wide. The height of the ice is about 3,000 feet, 300-400 feet above water and the rest below water.

https://www.youtube.com/watch?v=hC3VTgIPoGU
Title: Re: The caa-greenland mega crack
Post by: JayW on August 16, 2020, 07:41:41 PM
A brief peek through the clouds of the eddies north of Ellesmere Island.
Click to run
Title: Re: The caa-greenland mega crack
Post by: uniquorn on August 16, 2020, 10:38:49 PM
A brief peek through the clouds of the eddies north of Ellesmere Island.
That's a lot of eddies. The development awi amsr2 view, aug6-15
Title: Re: The caa-greenland mega crack
Post by: uniquorn on August 24, 2020, 11:56:36 AM
update using amsr2 awi(dev), jul17-23
cross posting worldview image, jul23, from the melting thread for reference. (light contrast enhancement)
Title: Re: The caa-greenland mega crack
Post by: uniquorn on September 07, 2020, 01:16:58 AM
shhh
Title: Re: The caa-greenland mega crack
Post by: bbr2315 on September 07, 2020, 03:41:16 AM
The year the crack became.... a partially open sea?
Title: Re: The caa-greenland mega crack
Post by: uniquorn on September 07, 2020, 01:36:08 PM
amsr2-uhh, jul21-sep6
Title: Re: The caa-greenland mega crack
Post by: Freegrass on September 07, 2020, 02:53:04 PM
Look at the speed of that floe that flies from the most northern tip of Greenland towards the Fram. Is that the speed of the current? Or was that aided by wind?
Title: Re: The caa-greenland mega crack
Post by: be cause on September 07, 2020, 05:18:27 PM
.. or was there a nuclear sub using it for cover ? :)
Title: Re: The caa-greenland mega crack
Post by: uniquorn on September 07, 2020, 11:46:42 PM
cyclone powered on sep2-4.  https://go.nasa.gov/3m2tht1 aug1-sep7
Title: Re: The caa-greenland mega crack
Post by: Glen Koehler on September 08, 2020, 07:03:23 AM
https://forum.arctic-sea-ice.net/index.php/topic,119.msg285372.html#msg285372
Monthly update from the Polar Science Center:
Quote
August 2020 Monthly Update
<snip>
 Ice thickness anomalies for August 2020 relative to 2011-2018 (Fig 6) continue the pattern that has emerged over the winter, spring and shows relatively thin ice along the Russian Coast and thicker than normal in the Eastern Beaufort and the along the Canadian Archipelago.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fpsc.apl.uw.edu%2Fwordpress%2Fwp-content%2Fuploads%2Fschweiger%2Fice_volume%2FBPIOMAS_ThicknessAnomalyCurrent.png&hash=e7157bf29f2adda140c9d0006442ab66)
    How does PIOMAS see thicker than normal ice on the north coast of Ellesmere when the AMSR2 shows a lack of land fast ice at same location for August 2020?  One of them has to be wrong.

https://forum.arctic-sea-ice.net/index.php/topic,2839.msg285417.html#msg285417
amsr2-uhh, jul21-sep6
Title: Re: The caa-greenland mega crack
Post by: oren on September 08, 2020, 08:56:03 AM
PIOMAS suffers from low resolution and does not "see" the crack. I bet it is the one that is wrong.
Title: Re: The caa-greenland mega crack
Post by: interstitial on September 09, 2020, 04:32:27 AM
There at least 6 different amsr2 products. There may be more.
Title: Re: The caa-greenland mega crack
Post by: uniquorn on September 09, 2020, 11:11:23 PM
The caa-greenland mega fracture https://go.nasa.gov/2FoXSQY