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igs

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Re: The 2020 melting season
« Reply #3500 on: July 23, 2020, 02:57:49 PM »
Something truly extraordinary must happen for 2020 to NOT beat 2019. And remember, 2019 itself slowed down after early August too. 2nd place is virtually guaranteed. The only question is whether 2020 could challenge and beat 2012. It has a buffer of almost 1M km2 right now, and that's a lot. This kind of buffer can manage several slow-downs as well. That all in my uneducated opinion.


All true while it should be added that the high-speed-melting in 2012 lastet "for ever" and that's what will decide. Without that upwelling caused by the 2012 GAC we won't see that melt-rate as long as in 2012 and 2012 can make up about 3/4 of the million withing 10 days in august and the remaining 300'000 km2 advantage of 2020 wil be decided upon when we see how long the steep dive lasts. In 2012 is was indeed extraordinary even after the GAC (due to warm salty water from depth)

igs

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Re: The 2020 melting season
« Reply #3501 on: July 23, 2020, 02:58:39 PM »
I think 4.0 mil km2 or above would require a miracle.


I think a safe bet is 3.2-3.6km2 min.

With a lean towards 2.7-3.1km2 min


Well analysed, hence my vote in the new poll on the topic.

Pagophilus

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Re: The 2020 melting season
« Reply #3502 on: July 23, 2020, 03:01:50 PM »
Lots of posts about possible cyclones associated with low pressure developing here & here.

But not a squeak about possible wind speeds? The force applied by the wind is proportional to the square of the wind speed. So a 50 km.p.h wind will apply 4 times the force of a 25 km.p.h. wind to a surface. Wind speed makes all the difference in the world ?

I guess also the state of the ice is important - wind howling across an unbroken flat ice sheet would be far less damaging than a somewhat lesser wind on a broken up ridged surface with multiple open water leads?

Good to have this clear reminder that helps reset my perspective, Gerontocrat.  Thank you.  I would add to wind speed the factor of how much time a weather system remains in place and therefore how long a wind blows in a given direction over the ice.

Let's suppose winds are not sufficient to actually mechanically degrade the ice or disturb the water much below the surface.  A wind that shifts direction, that only lasts a day or three, will likely not scatter the ice much.  And if wind directions change as the weather system shifts, then there will be some local stirring around of ice, but not widespread, dramatic ice scattering.  It was the long-term, consistent nature of the recent high (the 'GAAC'), acting over weeks, that kept wind directions generally consistent over most areas of the Arctic.  The winds themselves were not that strong, but their longevity was a large factor in concentrating the ice pack into its current position and the production of the current record low ice extents.   
« Last Edit: July 23, 2020, 03:08:45 PM by Pagophilus »
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igs

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Re: The 2020 melting season
« Reply #3503 on: July 23, 2020, 03:04:58 PM »
I fear for the Beaufort and surrounding seas;

Based on the worldview area measurement I did I think there is between 1.1M and 1.3M ice; Clouds make it more diffcult to have a good line :(

And seeing how bad the ice appears to be and how fast other parts of the arctic just disappeared/melted out, I won't be suprised if a large part of it will melt out in the next 2 weeks;

All true but I keep some hope for it's also well known and experience stubborness, going in circles and cooling itself.

BTW something that i've not seen posted yet would be a GAC that enters the arctic via Alaska/Canada and centers over the Beaufort. Perhaps it's meteorologially not likely, no clue, but if such a thing would happen ice is certainly doomed to below 2M km2

blumenkraft

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Re: The 2020 melting season
« Reply #3504 on: July 23, 2020, 03:08:30 PM »
It is remarkable that this year has not seen ice exported from the Lincoln Sea through the Nares Strait so far. Due to the HP, the ice was pushed west, not south even though the channel is open for some time now.

Maybe the change in air pressure can kickstart a southward current, which would lead to export, but i don't see indications for that as of now.

Freegrass

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Re: The 2020 melting season
« Reply #3505 on: July 23, 2020, 03:09:30 PM »
Moderate wind speeds such as 30 kts can develop pretty good wave heights if they are sustained over long fetches of open water. If those waves then move into ice, they may accelerate melting. The Beaufort high is able to move and melt ice in May by forcing upwelling along the coast when winds are maintained for a week.

However, weak lows that move around will not do what the GAC did. The warms winds coming off the continents will do more to damage the ice than weak lows moving about the Arctic ocean. Sustained intense lows like the GAC pull up water from below on the right hand side of the moving storm near the center of the low. Weak lows that meander may disperse the ice a bit but that's all. Gerontocrat is quite correct that the power of weak lows is far, far less than storms like the GAC. We should not be making comparisons of the impacts of the GAC with these weak lows.

Many of us watched the pole cam and saw moderate sized ridges form in the summer months but they covered a small percentage of the total area in the images and didn't contribute to the amount of compaction that some posters are asserting. I think that Oren was spot on when he wrote that our measure of compaction is apparently high because extent is at a record low.

Enough said.
I really have to disagree with you on this one FOoW. The forecast I just posted is giving us wind speeds above 40 Km/h, and those can really do some damage to the ice. Especially when the ice is weak.

And more importantly is the movement of the ice, which will speed up bottom melt. So I think these little storms can really do some damage, just by moving the ice, and as you said by wave action, and probably by mixing the water.
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binntho

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Re: The 2020 melting season
« Reply #3506 on: July 23, 2020, 03:38:02 PM »
Oren, compaction is well known to lead to ridging (I would not call it stacking) in 1D meshes (seen fron above) as the ice is rigid and fragile and it is the only way to alleviate pressure.
I don't find no reason to think this summer compaction has led to this in several places. I don't buy the 'as it compacts the exact amount of holes appear by meltout'. Many holes have indeed been seen but not in the central pack.
The burden of proof falls on those who claim there has not been ridging at all, not in those who claim the opposite. Thickening by pressure is a very well known feature of Arctic landscape.

But anyway, stormy August may destroy much of this, and this discussion may be forgotten.
I'm with Oren on this. I'd be extremely surprised to see any ridging resulting from mild winds at the height of the melting season. And I haven't seen any good arguments claiming otherwise.

The recent fall in concentration is not that massive anyway, and is probably not caused by any significant "compacting" by the slight winds as much as by fast melting of very dispersed ice on the Siberian side as can be seen very clearly in Aluminium's animation.

<Removed personal character claim. O>
« Last Edit: July 23, 2020, 06:16:21 PM by oren »
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Re: The 2020 melting season
« Reply #3507 on: July 23, 2020, 03:45:04 PM »
Just wondering, when will the ice in CAA start to give in. It seems like for much of CAA islands temperatures will remain nicely near +10C until the end of July.

I think we're going to lose a lot of the CAA ice very soon.

As of the 22nd, the Parry Channel is completely clear all the way through Barrow Straight, and the ice has broken up entirely right up to the edge of Viscount Melville Sound. During last year's "recovery", the VMS held out against the melt, but I just don't see how that's possible this time around. You can already see the first cracks forming between Victoria Island and Melville Island. Additionally, ice is breaking up in the Byam Channel, providing another angle of attack for open water against the VMS ice. Past the VMS, the other end of the Parry Channel -- the M'Clure Strait -- is under fairly heavy cloud. We know that the mouth of the M'Clure broke open as part of the Crack formation, vacuuming out ice from as far in as Crozier Channel. The remaining M'Clure ice is badly fragmented almost all the way to Liddon Gulf, and its fate may depend on how vigorous the northbound export is/becomes for the rest of the melt season.

Other core areas of the CAA aren't fairing better, either. Only scattered floes remain in the Wellington Channel, and Belcher Channel has broken up entirely and is beginning to clear. Melt and clearance in these areas is expected (in recent years, anyway), although the speed they've opened is surprising and worrisome. I suspect Byam Martin Channel will be the next major CAA waterway to break apart. On Worldview, there are stripes of darker ice throughout the area; this is telling, and is representative of the state of much of the CAA ice in general: blocks of relic MYI embedded in a matrix of younger, vulnerable ice. The clock is ticking down on that younger ice now. The earlier it breaks apart or melts out, the worse things will be for those MYI chunks. I expect some ice will survive in the CAA, but MYI ice isn't an all-or-nothing deal, and free-floating floes take damage from both above and below.

There are a few significant parts of the CAA that don't appear to be clear, clearing, or breaking up. The Prince Gustav Adolf Sea still seems okayish although high clouds obscure the details. There's some suggestion in Worldview that the PGAS may be starting to show the same characteristics as Byam Martin. That wouldn't be surprising, given how badly things got stirred around in the PGAS last year, but it's not quite there yet. In what might actually pass for good news, the Peary Channel / Sverdrup Channel / Massey Sound area looks pretty good, so far. I'm actually a bit surprised by that, because that whole area was simply savaged last year. Interestingly, the CAA/CAB boundary at the mouths of the Peary and Sverdrup is pretty much the only place where the Crack hasn't opened; there's no open water between especially the Sverdrup and the CAB. I think this makes clear that the mechanisms responsible for opening up the Crack are very bad for adjacent ice; those have spared the Sverdrup at least for now, and I have a tiny bit of hope that ice there might survive the season.

Elsewhere in the CAA... it's probably not going to be pretty in another couple of weeks.

BornFromTheVoid

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Re: The 2020 melting season
« Reply #3508 on: July 23, 2020, 03:55:52 PM »
NSIDC extent now lowest on record by 655k, and over a million km2 below the average of the last 10 years. We're 1.06 million km2 below the 2010s average, 1.98 million below 00s, 2.78 million below 90s and 3.31 million below the 80s.
https://twitter.com/Icy_Samuel/status/1286293031981912073

9 of the last 20 melt seasons will produce a minimum below 2012, and the 10 year average gets us down to 3.45 million km2. Slowest melt, 2001, will produce the 5th lowest minimum, at 4.21 million km2.
https://twitter.com/Icy_Samuel/status/1286294094910816258
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

glennbuck

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Re: The 2020 melting season
« Reply #3509 on: July 23, 2020, 04:07:36 PM »
1990,s melt will get us back up to 9 Million km^2 by the 31st of August.  :o

gandul

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Re: The 2020 melting season
« Reply #3510 on: July 23, 2020, 04:17:44 PM »
Oren, compaction is well known to lead to ridging (I would not call it stacking) in 1D meshes (seen fron above) as the ice is rigid and fragile and it is the only way to alleviate pressure.
I don't find no reason to think this summer compaction has led to this in several places. I don't buy the 'as it compacts the exact amount of holes appear by meltout'. Many holes have indeed been seen but not in the central pack.
The burden of proof falls on those who claim there has not been ridging at all, not in those who claim the opposite. Thickening by pressure is a very well known feature of Arctic landscape.

But anyway, stormy August may destroy much of this, and this discussion may be forgotten.
I'm with Oren on this. I'd be extremely surprised to see any ridging resulting from mild winds at the height of the melting season. And I haven't seen any good arguments claiming otherwise.

The recent fall in concentration is not that massive anyway, and is probably not caused by any significant "compacting" by the slight winds as much as by fast melting of very dispersed ice on the Siberian side as can be seen very clearly in Aluminium's animation.

I am being as careful or as careless as you, with the plus that very basic physics are on my side. Anticyclone winds have kept the pack under strong negative divergence for 20 days, many floes half melting will be crushed by this, but there are areas where I can see 1m ice simply buckles and forms ridges, as always been.

Do you have a super telescope satellite to really check on the state? Neither do I. I propose to wait and see.

<Edited quote. O>
« Last Edit: July 23, 2020, 06:17:36 PM by oren »

Alphabet Hotel

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Re: The 2020 melting season
« Reply #3511 on: July 23, 2020, 04:33:39 PM »
Through a gap in the clouds, you can see this area is breaking up. The northernmost cracks visible are around 86N.


Paul

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Re: The 2020 melting season
« Reply #3512 on: July 23, 2020, 04:38:09 PM »
Some interesting observations on worldview today.

Firstly, we may be seeing the first signs of ice incorrectly melting on the sensors in the ESS, today's worldview image shows there is still some very thin ice in the ESS despite the sensors suggesting it melted out so we may see that thin ice appearing on tomorrow's Breman update?

The second thing and it's a more concerning one for compaction of the ice is on the Atlantic side, the winds have switched and the ice is dispersing. Although obviously not unheard of but its perhaps going to suspect some people's thoughts that maybe the ice is compacted but its really is quite thin.

Lastly,  the ice retreat on the Siberian side has finally more or less stopped but again if the ice spreads out too much, I'll start to suspect any compaction in the CAB willl reduce quickly making it more vulnable for the rest of the melt season.

Tom_Mazanec

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Re: The 2020 melting season
« Reply #3513 on: July 23, 2020, 04:48:40 PM »
BFTV, you just made it obvious to me that the decade averages are declining at an accelerating pace.
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Juan C. García

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Re: The 2020 melting season
« Reply #3514 on: July 23, 2020, 05:00:34 PM »
Beaufort thinning out already. Big block in the middle 'pulverised'
amsr2-uhh, jul12-22 click

July 18-22.

2019.

Great GIF's as always!
Thank you, both!  :)
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

Pagophilus

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Re: The 2020 melting season
« Reply #3515 on: July 23, 2020, 05:16:10 PM »
Oren, compaction is well known to lead to ridging (I would not call it stacking) in 1D meshes (seen fron above) as the ice is rigid and fragile and it is the only way to alleviate pressure.
I don't find no reason to think this summer compaction has led to this in several places. I don't buy the 'as it compacts the exact amount of holes appear by meltout'. Many holes have indeed been seen but not in the central pack.
The burden of proof falls on those who claim there has not been ridging at all, not in those who claim the opposite. Thickening by pressure is a very well known feature of Arctic landscape.

But anyway, stormy August may destroy much of this, and this discussion may be forgotten.
I'm with Oren on this. I'd be extremely surprised to see any ridging resulting from mild winds at the height of the melting season. And I haven't seen any good arguments claiming otherwise. Your's certainly don't count, Gandul, perhaps a bit more care the next time?

The recent fall in concentration is not that massive anyway, and is probably not caused by any significant "compacting" by the slight winds as much as by fast melting of very dispersed ice on the Siberian side as can be seen very clearly in Aluminium's animation.

I am being as careful or as careless as you, with the plus that very basic physics are on my side. Anticyclone winds have kept the pack under strong negative divergence for 20 days, many floes half melting will be crushed by this, but there are areas where I can see 1m ice simply buckles and forms ridges, as always been.

Do you have a super telescope satellite to really check on the state? Neither do I. I propose to wait and see.

"strong negative divergence"... aka "convergence"  ;).   Seriously, though, gandul, I think you are using the best terms, and I can't think why I would have not thought to do the same.

So, to prevent confusion, we can say anticyclones, like the 'GAAC', make ice floes converge (and so extent drops and sometimes concentration rises) and that cyclones tend to make ice floes diverge.  Well defined language is vital to preventing needless debate and misconceptions... I have seen this over and over and over in life, education and science.  Maybe since there is no evidence for ice thickening, and so the term compaction (which I myself, used, before I became the far better person I am now  ::)  ) is best avoided here.  One can speculate, which can be fun and productive, but I think in summer evidence is needed for serious discussion.  In winter, when the ice is locked solid, one can infer compaction, however.

Binntho, I think there is incontrovertible evidence that the 'GAAC' cyclone drove down the extent numbers by causing the icepack floes to converge northwards (see my animation on reply #3359 ).  I am not saying that the ice edges did not also melt back a lot (they did), but the two processes can be happening at once and were, visibly, happening at once.   

« Last Edit: July 23, 2020, 05:25:36 PM by Pagophilus »
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Pagophilus

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Re: The 2020 melting season
« Reply #3516 on: July 23, 2020, 05:36:34 PM »
The ice pack is looking fragile in a zone up to 250km deep N of FJL today (July 23), where there happens to be little cloud.  The 'layered' appearance of the gaps makes it seem to me almost like the ice cap is 'relaxing' into a strong melting phase.  I hope not.

The wide gap at bottom left is about 450km from the pole.

First image is a 'closeup', pushed for contrast on Photoshop.
Second image is to give general context.
« Last Edit: July 23, 2020, 05:42:36 PM by Pagophilus »
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binntho

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Re: The 2020 melting season
« Reply #3517 on: July 23, 2020, 05:37:38 PM »
Binntho, I think there is incontrovertible evidence that the 'GAAC' cyclone drove down the extent numbers by causing the icepack floes to converge northwards (see my animation on reply #3359 ).  I am not saying that the ice edges did not also melt back a lot (they did), but the two processes can be happening at once and were, visibly, happening at once.

Undoubtedly incontrovertible and I wouldn't dreem of thinking otherwise. This is what anticyclones do, as we all know. But I'd claim that they extert nowhere near the pressure and forces necessary to cause any discernible ridging in the current situation.

Gandul's and your's claims seem to be that if there is convergence, there has to be ridging as per some immutable law of physics. And even lacking a telescope, gandul "sees" areas of buckling and ridging which is whishful thinking if there ever was.

The physics of the situation are against ridging, simply because the pressures involved are nowhere near strong enough, particularly considering that the icepack itself is not a hard frontier but ever shifting and floating, an elastic barrier that moves with the prevailing winds. Any incidental stacking will quickly resolve iself in the absence of freezing temperatures, and shifting is easier than buckling when everything is in constant flux anyway.

And to recap my previous point: A lot of the apparent increase in concentration is not anticyclone driven compaction but the rapid melt of the most dispersed ice. Nothing in this situation indicates floes bumping against each other hard enough to buckle, whether for lust or procreation.
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sedziobs

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Re: The 2020 melting season
« Reply #3518 on: July 23, 2020, 05:46:46 PM »
Last year A-Team made this comment about ridging in the Test Space:

The MYI ice is then pushed ahead of the 'diagonally' moving boundary that is mixed zonal and meridional in character. It has piled up against Svalbard and Lincoln Sea/Greenland in addition to exiting the Fram.

I would not expect much over-rafting of floes at these thicknesses; the lack of concentration deficit does not allow compaction; ridging occurs but has a small areal effect. Ice is not a viscous deformable plastic though it can be effectively modeled as if it were.


Pagophilus

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Re: The 2020 melting season
« Reply #3519 on: July 23, 2020, 05:49:37 PM »
Binntho, I think there is incontrovertible evidence that the 'GAAC' cyclone drove down the extent numbers by causing the icepack floes to converge northwards (see my animation on reply #3359 ).  I am not saying that the ice edges did not also melt back a lot (they did), but the two processes can be happening at once and were, visibly, happening at once.

Undoubtedly incontrovertible and I wouldn't dreem of thinking otherwise. This is what anticyclones do, as we all know. But I'd claim that they extert nowhere near the pressure and forces necessary to cause any discernible ridging in the current situation.

Gandul's and your's claims seem to be that if there is convergence, there has to be ridging as per some immutable law of physics. And even lacking a telescope, gandul "sees" areas of buckling and ridging which is whishful thinking if there ever was.

It seems then we agree on all points.   :)   

My fault on the first point above, probably, for thinking you did not think convergence was occurring.  I will read more carefully.

And as to the ridging/compaction issue, I think if you reread what I wrote, that I agree here also.  I effectively say that ridging/compaction should not be part of the conversation unless there is actual evidence.  Absent that, I am with you, we know that the ice floes have converged, and there is no evidence to posit thickening of the pack.

As to ice piling up against islands etc when there are strong winds and current, I guess some compaction is possible, but that is not what is under discussion here, and it is a minor effect, I believe, in this situation.
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binntho

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Re: The 2020 melting season
« Reply #3520 on: July 23, 2020, 05:50:23 PM »
Last year A-Team made this comment about ridging in the Test Space:

The MYI ice is then pushed ahead of the 'diagonally' moving boundary that is mixed zonal and meridional in character. It has piled up against Svalbard and Lincoln Sea/Greenland in addition to exiting the Fram.

I would not expect much over-rafting of floes at these thicknesses; the lack of concentration deficit does not allow compaction; ridging occurs but has a small areal effect. Ice is not a viscous deformable plastic though it can be effectively modeled as if it were.
But talking about "piling up" against fast land. Which is how ridging most easily forms. Ice floating with it's fellows in a general feeling of harmony and fellowship does not suddenly start jumping up on each other to buckle and ridge, unless for the purposes specified earlier.
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binntho

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Re: The 2020 melting season
« Reply #3521 on: July 23, 2020, 05:51:45 PM »
It seems then we agree on all points.   :)   
With good fellowship and cheer! And I perhaps better stop commenting now, the Habesha beer is rising to my head ...
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tybeedave

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Re: The 2020 melting season
« Reply #3522 on: July 23, 2020, 05:51:58 PM »
i agree with Friv, it will take a miracle, i believe in miracles, but i don't seee it on the menu presently.

paraphrasing a poem posted a few posts back

'the ice don't care what you think, it just melts'

the ice has endured 4 killer body punches already, all extreme melt events

huge export in spring
nearly a month of continuous mild cyclone
long-lasting anticyclone
related extreme insolation (thru a very clear atmosphere)

even a moderate cyclone in august will be a knock out punch to more than just the records

and to conservative (compaction) thinkers...."it just melts'. 

am i happy to say this?  no, but it does appear to me that by watching the future unfold, it may help us prevent santa's eviction from his workshop.

i remain watching

td

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oren

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Re: The 2020 melting season
« Reply #3523 on: July 23, 2020, 06:01:28 PM »
Folks, if anyone wants to comment again on the ice ridging/over-rafting issue, please do so in a separate thread, whether you support "my" position or not doesn't matter, just that the issue deserves its own thread. (I've been away for a few hours and too many messages have gone by for me to start moving messages piecemeal to a new thread at this time).

Jim Hunt

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Re: The 2020 melting season
« Reply #3524 on: July 23, 2020, 06:05:50 PM »
Just wondering, when will the ice in CAA start to give in.

You may wish to peruse the shiny new "When will the Northwest Passage 'open' in 2020?" poll?
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oren

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Re: The 2020 melting season
« Reply #3525 on: July 23, 2020, 06:10:19 PM »
A couple of interesting items from other threads. First a great video posted by user seaice.de (Prof. Lars Kaleschke from AWI, formerly from UH) in the Mosaic thread.

Quote
The @MOSAiCArctic ice floe speeds up southwards and goes down the drain in Fram Strait

This experimental AMSR2 product enhances refrozen leads.

Polarstern and Fram track are hopefully better distinguishable for red-green color-blind.

Methods and data: doi.org/10.3390/rs6053841 doi.org/10.5194/tc-6-343-2012 doi.org/10.7265/N5MS3QNJ

Note the blue line shows the Polarstern itself, including the maneuver it made sailing to Svalbard and back to the floe.

I thought the video was well worth it even for seeing the crazy amount of export that took place earlier in the year, especially March-April.



jdallen

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Re: The 2020 melting season
« Reply #3526 on: July 23, 2020, 06:17:26 PM »

Losses on jaxa the last 7 days have averaged 126k, and 127k for the month of July. Nothing is ever 100% certain I suppose, especially when it comes to meteorology and the cryosphere, but given the forecast over the next week some kind of slowdown from those lofty numbers seems very, very likely; barring some sort of GAC beyond day 4. How much is anybody’s guess, but I do agree that tons of heat has already been added to the system, which should reduce the slowdown via bottom melt and momentum. That said, I would be very surprised if we averaged over 100k in losses on jaxa for the next 7 days, but we’ll see... the arctic has definitely surprised and humbled me many times before.
<snippage>
My bolding in the quote.  It is for exactly that reason I think the current trend will continue for several days - perhaps as much as a week - past the weather change.

There are very large regions of the ESS, Chukchi and Beaufort that are coming apart, and if I recall, the CAA will continue to be hot.  They've built up an enormous heat budget, which they can't dump fast enough.  The ice will suffer the result.
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Pagophilus

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Re: The 2020 melting season
« Reply #3527 on: July 23, 2020, 06:23:18 PM »
Just wondering, when will the ice in CAA start to give in.

You may wish to peruse the shiny new "When will the Northwest Passage 'open' in 2020?" poll?

Oh my, it IS shiny!  Everyone should visit!  And vote. 
Person.  Woman.  Man.  Vote.  November.

jdallen

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Re: The 2020 melting season
« Reply #3528 on: July 23, 2020, 06:29:29 PM »
<snippage>
One thing I will not allow further without some references - the claim that ice in the middle of the ocean is ridged and stacked in the summer under a HP ("compaction") regime.
<snippage>
Thank you.  I agree, references really are needed, but may be in short supply, especially in the face of compelling anecdotal observations (from the Polar Stern's expedition) which show no sign of it.  The lack of discussion by those scientists itself is compelling. If it were widespread, I'm fairly sure we would be reading about it.
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Sublime_Rime

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Re: The 2020 melting season
« Reply #3529 on: July 23, 2020, 07:31:57 PM »
GFS 12Z seems to converge towards what the GEM model has been showing for the past day or so, a LP centered over the east Beaufort 3-4 days out and slowly moving towards the central CAB. GFS bottoms it out just under 980 hPa, with a decent spread of winds over 30kts (reaching up to 45 or so kts) sustained for about 2 days. The GEM on the other hand (not enough experience to know whether this model can be trusted) brings the low down to under 960 hPa, with a huge pressure gradient to the HP over the Barents at >1030 hPa.

Both solutions have a pretty steep temp gradient from the HP to the low, so I think both would be bad for the ice. With much of the CAB and CAA in high temp anomalies, the Atlantic side under HP, and the Beaufort getting sloshed around with neighboring warm open water. Regardless of the depth of LP, the WAA and HP seem very consistent across models, including the Euro, which had a sub 980 hPA LP later out at 6-7days on the 00Z. The HP over the Barents will also serve, in combo with the LP, to push much of the CAB ice into the warm Laptev and ESS. I expect this to increase extent, but increase bottom melt substantially.

I think the only ice-retaining formula at this point is prolonged weak LP or weak HP, as GAC-type storms will lead to mixing with the ridiculously heated open water surrounding most of the ice, while strong HP seems to consistently bring with it considerable WAA from both continents (and this warm air would then predispose to deeper LP systems). 2020 has a fine line to walk to avoid losses that would bring it close to (<3.5M) or past the record, imho.

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« Last Edit: July 23, 2020, 07:41:20 PM by Sublime_Rime »
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Aluminium

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Re: The 2020 melting season
« Reply #3530 on: July 23, 2020, 07:44:12 PM »
The thinnest ice easily can be broken under moderate pressure. I saw what happens with floes in rivers. They turn into white mix near cracks if the ice is thick and turn into white mix completely if the ice is thin. I guess, the same process had a place just north of the Laptev Sea a week ago.

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Re: The 2020 melting season
« Reply #3531 on: July 23, 2020, 08:25:49 PM »
Environment Canada seem to suggest that most of the CAA is likely to stay rather warm from late July to late August. They got it right last month.
( https://weather.gc.ca/saisons/image_e.html?img=mfe1t_s )

If the CAA channels melt out, presumably an invitation for the Garlic Press to move into high gear - if winds & currents oblige?
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Re: The 2020 melting season
« Reply #3532 on: July 23, 2020, 08:55:27 PM »
The thinnest ice easily can be broken under moderate pressure. I saw what happens with floes in rivers. They turn into white mix near cracks if the ice is thick and turn into white mix completely if the ice is thin. I guess, the same process had a place just north of the Laptev Sea a week ago.


Pressure in rivers is mostly huge and not moderate, at least in times of breakups.

Lord M Vader

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Re: The 2020 melting season
« Reply #3533 on: July 23, 2020, 09:07:15 PM »
Seems like the CAA will get smoked next 10 days according to the EURO. Atlantic side will remain warm the upcoming 10 days. The Pacific side will be cold but it remains to see how deep and persistent the LP will be.


El Cid

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Re: The 2020 melting season
« Reply #3534 on: July 23, 2020, 09:10:56 PM »
I was thinking about 2012 vs 2020.

I think that the big difference is that the 2012 GAC did not add net energy to the system - on the contrary! - it simply "brought up heat" from the ocean that temporarily melted the ice but then this energy was lost during the fall through radiation to space (hence the recovery years of 2013 and 14)

The 2020 GAAC however added net new energy to the system through insolation and this energy will (at least for a good while) stay in the system (ie. will be stored in the Arctic Ocean). Probably at least until winter but likely longer.

I believe 2020 has the chance to be a (Arctic and NH) climate  game changer just like 2007 was...

gandul

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Re: The 2020 melting season
« Reply #3535 on: July 23, 2020, 09:35:44 PM »
I was thinking about 2012 vs 2020.

I think that the big difference is that the 2012 GAC did not add net energy to the system - on the contrary! - it simply "brought up heat" from the ocean that temporarily melted the ice but then this energy was lost during the fall through radiation to space (hence the recovery years of 2013 and 14)

The 2020 GAAC however added net new energy to the system through insolation and this energy will (at least for a good while) stay in the system (ie. will be stored in the Arctic Ocean). Probably at least until winter but likely longer.

I believe 2020 has the chance to be a (Arctic and NH) climate  game changer just like 2007 was...
I don’t see essential difference here, perhaps quantitative but not qualitative. The GAC pulled energy from the ocean that had been stored *mostly* during that summer 2012 and made it available to ice broken and battered by same storm. Arctic amplification ensued, freezing was delayed during Fall.
Same could happen this year, why not?
Where’s the difference apart from the fact that this year is eight years warmer and that maybe covid played a role. I see the difference with storm dominated years like 2013, 2016 or simply Spring-delayed years like 2014 or 2017. But not with 2012.

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Re: The 2020 melting season
« Reply #3536 on: July 23, 2020, 10:21:48 PM »
I don’t see essential difference here, perhaps quantitative but not qualitative. The GAC pulled energy from the ocean that had been stored *mostly* during that summer 2012 and made it available to ice broken and battered by same storm. Arctic amplification ensued, freezing was delayed during Fall.
Same could happen this year, why not?

I think the heat brought up from the GAC in 2012 was stored over several years. Oceans have the ability to store large amounts of energy for a couple of years. Otherwise the "recovery" of 2013-2014 wouldn't make any sense: why a two year recovery for a single year event?

Same could happen this year, sure. But a GAC (or something equally intense) will have to happen to turn 2020 in a game changer like 2007 and 2012. My uneducated guess in probabilities is that this year has a 60% chance of an average August melt and will end up 2nd. And theres is a 20% chance of al below average melt and also a 20% chance of a big melt event.
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Re: The 2020 melting season
« Reply #3537 on: July 23, 2020, 10:45:38 PM »
I have created a new thread on the science of ridging and rafting in the hopes that we can begin to answer some of the questions that have come up in this thread:

https://forum.arctic-sea-ice.net/index.php/topic,3210.msg276496/topicseen.html#msg276496

Yuha

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Re: The 2020 melting season
« Reply #3538 on: July 23, 2020, 10:50:04 PM »
A couple of comments about Beaufort melt.

First, the Beaufort extent at this point in different years is probably more a reflection of ice drift than ice melt.

Second, Beaufort often has regions of very thick, old ice that has drifted there from the north of CAA. Such ice can act as a barrier that stops or slows down the melt for a long time. Once the barrier breaks, the ice behind it can collapse quickly.

An extreme example of such a collapse is 2012 shown in the gif below. Notice that the collapse happened before GAC.

However, I should point out that summer 2012 was dominated by a dipole pattern with a high parked over Beaufort bringing a lot of heat and sunshine. This summer Beaufort has been cooler and cloudier, so I don't expect as early and as spectacular collapse this year.

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Re: The 2020 melting season
« Reply #3539 on: July 23, 2020, 10:51:43 PM »
Have we been discussing a thread on Aerosol masking effect from the Lockdown a global reduction in 20% of industrial activity can cause a 0.5 C to 1 C jump in global temperatures in a matter of months, might explain the crazy July we have had and past Data not being as accurate this year as it is usually very good and accurate in the past.

I would normally be happy to go with JAXA predictions for September Minimum for all past years currently in the range of 3.21 million km^2 for September but feel we could get a strange result this year due to the 3 month lockdown worldwide. Making me wonder if something crazy could happen and we end around 2012 melt season ice loss of 3.86 million km^2, that is the remaining ice loss from July 22nd 2020 to the September low from 2012!

https://guymcpherson.com/2019/10/the-aerosol-masking-effect-a-brief-overview/
« Last Edit: July 23, 2020, 11:20:58 PM by glennbuck »

bbr2315

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Re: The 2020 melting season
« Reply #3540 on: July 23, 2020, 10:59:06 PM »
EURO and HYCOM show a collapse worse than 2012 in Beaufort and Chukchi is now beginning and about to accelerate.


marcel_g

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Re: The 2020 melting season
« Reply #3541 on: July 23, 2020, 10:59:08 PM »
Have we been discussing a thread on Aerosol masking effect from the Lockdown a global reduction in 20% of industrial activity can cause a 0.5 C to 1 C jump in global temperatures in a matter of months,
We have a discussion here, if that’s your question: https://forum.arctic-sea-ice.net/index.php/topic,3202.0.html

Michael Hauber

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Re: The 2020 melting season
« Reply #3542 on: July 24, 2020, 12:30:28 AM »
Some noticeable dispersion on the Atlantic front

Been cloud covered here for quite a while, but this image from the 13th gives an idea of how compact the area had been previously.

GFS forecasts some fairly extreme heat for this region in the next few days, with 850hp temps at +8.  Melting in this region is very hard (until the ice gets out into the Atlantic proper), but will be worth watching just in case.
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glennbuck

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Re: The 2020 melting season
« Reply #3543 on: July 24, 2020, 12:46:31 AM »
After 68 years the record highest temperature of Chokurdah ,Yakutia (70N) fell : 32.0C was recorded today. From tomorrow the Siberan heat wave is expected to move further east and persist for the rest of the week in the Chukotka Region.

glennbuck

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Re: The 2020 melting season
« Reply #3544 on: July 24, 2020, 12:51:29 AM »
Siberia Wildfires continue to produce huge amounts of energy & smoke emissions significantly greater than 2019 & 2003-2018 mean. July 2020 total estimated carbon emissions are already highest in the 18 years of #CopernicusAtmosphere


be cause

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Re: The 2020 melting season
« Reply #3545 on: July 24, 2020, 01:14:48 AM »
There ain't no stoppin' it now .. https://go.nasa.gov/39oSyYL
  for the 1'st time in 10 days we get to see the unfolding horror of the Atlantic side . Pagophilus showed the damage north of FJL . I see it extends as far as can be seen .. 86.5'N . The state of the ice here is as bad or worse than the ice between Laptev and pole . Coupled with the video of Polarstern and the ice flow , I see no reason for any of the ice on the Eurasian side of the meridian 0/180' to survive .
  this update has just been patched into worldview .. between G'land and the pole .. the hue of the blue has darkened and it is easy to see water between the rubble = trouble . It looks as if even here in the bastion of ice there is no defence . Looks like only 5% of the ice here would make it through a serious assault .. the whiter blocks and specks . 
     https://go.nasa.gov/39pnnwi

  of course , weather and seasons changing may delay the inevitable for another year .

  b.c.
« Last Edit: July 24, 2020, 02:48:13 AM by be cause »
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 + 2 = 2021 
 (phew)

JayW

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Re: The 2020 melting season
« Reply #3546 on: July 24, 2020, 01:21:46 AM »
Corner of Banks island in the lower left corner.  Parry channel breaking up, starting to sway with the tides.
Contrast enhanced.  Click to run. 34 hour loop.

 
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Glen Koehler

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Re: The 2020 melting season
« Reply #3547 on: July 24, 2020, 01:56:47 AM »
     The GFS pressure and surface temp forecast for July 26 18Z to July 29 18Z looks like three days of heavy damage to the Beaufort.  Nothing like GAC2012 but pressure consistently in 980s for most of those three days with relatvely warm temps.  I don't have the actual wind speeds but the tightness of the pressure isoclines suggest it will be a-blowin'.
https://climatereanalyzer.org/wx/fcst/?mdl_id=gfs&dm_id=arc-lea&wm_id=t2anom#gfs.arc-lea.t2anom

   At the same time the temperature forecast for the CAA - northern Greenland - North Pole triangle also looks bad, and also along the entire Atlantic front.

    If this forecast verifies I don't see that slow down that's been talked about actually showing up.
I don't have the meteorological expertise to be too declarative about any of this, but the sheer persistence and scale of melt pressure, on top of what must be residual heat in the water from the abnormally clear sky in July, suggests that 2020 is not slowing down and that the ice is taking a beating that will push it well below 2012.





« Last Edit: July 24, 2020, 02:30:50 AM by Glen Koehler »

Often Distant

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Re: The 2020 melting season
« Reply #3548 on: July 24, 2020, 03:13:23 AM »

Nullschool ocean temperature comparison. 23 July 2019 on the left vs 23 July 2020 to the right.

Frivolousz21

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Re: The 2020 melting season
« Reply #3549 on: July 24, 2020, 03:20:40 AM »
There ain't no stoppin' it now .. https://go.nasa.gov/39oSyYL
  for the 1'st time in 10 days we get to see the unfolding horror of the Atlantic side . Pagophilus showed the damage north of FJL . I see it extends as far as can be seen .. 86.5'N . The state of the ice here is as bad or worse than the ice between Laptev and pole . Coupled with the video of Polarstern and the ice flow , I see no reason for any of the ice on the Eurasian side of the meridian 0/180' to survive .
  this update has just been patched into worldview .. between G'land and the pole .. the hue of the blue has darkened and it is easy to see water between the rubble = trouble . It looks as if even here in the bastion of ice there is no defence . Looks like only 5% of the ice here would make it through a serious assault .. the whiter blocks and specks . 
     https://go.nasa.gov/39pnnwi

  of course , weather and seasons changing may delay the inevitable for another year .

  b.c.
.

This is exactly what I mean it's only freaking July 23rd.

2020 is going to finish lowest in area, extent, and volume
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