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Pagophilus

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Re: The 2020 melting season
« Reply #2550 on: July 11, 2020, 03:49:29 AM »
Ice at the Nares, patiently waiting its turn...

Worldview, contrast tweaked heavily on Photoshop.
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VeliAlbertKallio

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Re: The 2020 melting season
« Reply #2551 on: July 11, 2020, 04:21:46 AM »
Aggressive melting in 2020 has been factored in May-June 2020 in some GCMs which see the jet streams pushed from north of Britain further south to guide depression systems in such a way that:
"Atlantic storms will sweep on to the coasts of Morocco, Portugal and France in December 2021." ZoW. A pre-requisite of this is aggressive melting and warming of Arctic this summer chained to the next one. The delayed winter re-freezing in the Arctic Ocean occurring about eight weeks later than before. BOE not yet factored in. Anyone thought with how truncated this coming winter season will be?  :o

I think the Lincoln Sea will empty out in the next week. The ice in the north sea will float towards

Beaufort and the ice closer to Nares will enter Nares. IMO. The last of the Kara Sea ice (near severnaya zemlya) looks set for destruction as a LP system looks set to stir the ice while pushing it into warmer waters.


QUESTION: If a 2012esque GAC occurs and everything gets stirred up, what is the likelihood of mixing to the point where afterwards the stratified layer of cold fresh water/ice is only a fraction of what it was before? If this happened, would a near BOE be most likely every year heretofore?
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ArcTickTock

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Re: The 2020 melting season
« Reply #2552 on: July 11, 2020, 05:52:06 AM »
RE: #2478 bathymetry

Love this post blumenkraft!  Are you trying to point out the similarity in the boundary between the deep Arctic Basin and the boundary of the minimum each year, there is certainly a relationship.

Phoenix

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Re: The 2020 melting season
« Reply #2553 on: July 11, 2020, 05:59:20 AM »
RE: #2478 bathymetry

Love this post blumenkraft!  Are you trying to point out the similarity in the boundary between the deep Arctic Basin and the boundary of the minimum each year, there is certainly a relationship.

There is definitely a relationship. Can be overcome, but not easy. WAA from Siberia or NAM will overcome some of it and endless compaction could do the trick on the Atlantic side.
« Last Edit: July 11, 2020, 12:25:04 PM by Phoenix »

Aluminium

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Re: The 2020 melting season
« Reply #2554 on: July 11, 2020, 06:33:12 AM »
July 6-10.

2019.

Michael Hauber

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Re: The 2020 melting season
« Reply #2555 on: July 11, 2020, 06:52:43 AM »
Surprising how much cloud cover there is visually considering the high pressure.  Low cloud/fog?  Warmer moist air from outside the Arctic hitting the cold ice and condensing fog?  Even though I'd think most of the air would be quite dry as it is sinking air from higher levels within the strong high, but if its warm enough it would have enough moisture to condense into cloud/fog as it approaches 0.

Much of the fringe has been hidden in cloud, and hard to get a good view, and some of this cloud is thicker as well, so perhaps not as much melting at fringe.  Ridge is currently in Siberian sector giving great view of poor ice condition there.  Weak upper trough in Beaufort looks to intensify and head towards Siberia and cool things there, but maybe also eventually form low pressure at surface and stir winds up.  Ice there would seem to be doomed regardless.  Another surface trough looks to create some substantial winds in Laptev sector as it squeezes against the central high.  This will push ice rapidly towards Greenland side of the Atlantic.  Longer term the Beaufort low strengthens enough to form strong winds back towards Laptev from central pack which would be interesting, but this is week two so not really in the reliable forecast window.

I'd expect the strongest melt is in central pack.  Is this mostly just thickness loss?  Or are lots of tightly jammed together floes losing a little bit around the edge, so that the floes then continue to be jammed together by the convergent forces of the high pressure Ekmann pumping and result in loss around the fringes?
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Killian

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Re: The 2020 melting season
« Reply #2556 on: July 11, 2020, 07:42:24 AM »

Just average for the five lowest extent years puts 2020 298 sq km. below 2019 two weeks from now. Hold on to your hats.

So you take the lowest value for the date (this year) and extrapolate from there the biggest losses

That is not what I did. I didn't check which years had the biggest losses, I just took the years with the lowest ultimate extent. For any 2-week period, virtually any year could be "the biggest loss." 2018, e.g., averaged 104. If I'd wanted to cherry-pick, I could have, and would have.

Quote
you get a new record low? Who would have thought?

 :) ;)

I thought it was an interesting point as the 100 sq km+ melt days do not have to continue, do they? Just an average of those otherwise random years still results in a wider gap than exists at present. That bodes ill to my mind.

Your mileage clearly varies.

Killian

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Re: The 2020 melting season
« Reply #2557 on: July 11, 2020, 07:51:47 AM »

Just average for the five lowest extent years puts 2020 298 sq km. below 2019 two weeks from now. Hold on to your hats.

So you take the lowest value for the date (this year) and extrapolate from there the biggest losses, and you get a new record low? Who would have thought?

 :) ;)
Yep, it's not a great mathematical surprise but thinking about it, what are the odds 2020 is not among the top five loss years for the rest of the month? Or the rest of the season?

CO2e forcing is stronger every year, 3 out of last 5 years are among the top five and 2020 has certainly proven to be a strong melt season.

But as we all know, since 2012 the mid and late summers have turned positive for max ice retention and that could happen again. But the lower the ice extent at any given marker, the more likely better conditions later don't avoid a new low. Two of those years were in the 80k range. That's nothing spectacular, yet we still end up with a large new low record anomaly.

That said, I am of the opinion the climate is having or has had a phase change the last couple of years, and change, in general, has jumped to a faster rate of warming. My primary logic for this is that there is no unexpected or unusual forcing in play the last two years, yet look at global temps. Where is all that energy coming from? So... yeah... perhaps not so surprising with the hindsight of how this season has gone.

Killian

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Re: The 2020 melting season
« Reply #2558 on: July 11, 2020, 07:57:58 AM »
The odds of finishing >4 mil sq km are very low IMO.

Agreed, as per my prediction on the July September minimum thread. What really scares me if the extent is 300k sq km or more into record territory in mid-July and the high melt conditions persist for the summer, I don't see how we avoid a new low.

blumenkraft

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Re: The 2020 melting season
« Reply #2559 on: July 11, 2020, 08:01:00 AM »
Thank you.  The icecap edge seems to be aligning remarkably closely with the 200m submarine contour.  Coincidence maybe, but it means, IMHO, that the conversation here should include what is happening with waters beneath the ice more extensively than our replies do now.

Welcome, Pagophilus. :) I'm trying to find out in which part this is caused by bathymetry and which by atlantification. And those two variables are somehow interconnected insofar that the warm water coming from the south is descending into the depth of the Arctic basin here.

Moah data needed...

BTW, this is the site that provided the data for this GIF >> https://oden.geo.su.se/map/

Love this post blumenkraft!  Are you trying to point out the similarity in the boundary between the deep Arctic Basin and the boundary of the minimum each year, there is certainly a relationship.

Thank you. :)
« Last Edit: July 11, 2020, 08:19:46 AM by blumenkraft »

blumenkraft

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Re: The 2020 melting season
« Reply #2560 on: July 11, 2020, 08:11:04 AM »


Ken, blue ice is glacier ice. I've never seen blue sea ice.

About your question about snow depth. I'm not quite sure one could see it in the satellite images. Maybe people refer to buoy data when they make such a claim?

Pmt111500

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Re: The 2020 melting season
« Reply #2561 on: July 11, 2020, 08:39:58 AM »


Ken, blue ice is glacier ice. I've never seen blue sea ice.

About your question about snow depth. I'm not quite sure one could see it in the satellite images. Maybe people refer to buoy data when they make such a claim?

Well, on satellite images the melting sea ice may look blue for a while. Refractions from melting pools I guess. Also, the very oldest sea ice way back when there was 10 year-old  sea ice looked visibly blue on photos. Not as blue as glacial ice though.

bbr2315

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Re: The 2020 melting season
« Reply #2562 on: July 11, 2020, 09:39:41 AM »
Tonight's 00z EURO does as I feared and has progressed to advecting a portion of the heat over Eastern North America into the GAAC-20 event by D6-7. I think this flux to the Arctic / CAB will increase in subsequent modeling.


blumenkraft

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Re: The 2020 melting season
« Reply #2563 on: July 11, 2020, 09:44:27 AM »
way back when there was 10 year-old.

That was before my time, Pmt! ;)

Do you know, what's causing 10yo ice to appear blue? I mean, sea ice is not constantly under pressure, which causes the glacier ice to develop its bluish tint.

Pmt111500

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Re: The 2020 melting season
« Reply #2564 on: July 11, 2020, 10:20:20 AM »
way back when there was 10 year-old.

That was before my time, Pmt! ;)

Do you know, what's causing 10yo ice to appear blue? I mean, sea ice is not constantly under pressure, which causes the glacier ice to develop its bluish tint.
My guess would be the freshening of old ice by salt extrusion, and the layers built in successive winters.

JayW

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Re: The 2020 melting season
« Reply #2565 on: July 11, 2020, 10:30:12 AM »
12 hour loop using snow RGB, the darker the red, the wetter it is.  Requires a click.  Second is AMSR2 concentration, rotated to match.  I often hear it stated that water vapor laden clouds cause an apparent decrease in concentration, I don't see it that way.  Sometimes the sensor picks up the wet surface from rain underneath.  My experience is that cloud cover almost always creates an apparent increase in concentration.


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blumenkraft

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Re: The 2020 melting season
« Reply #2566 on: July 11, 2020, 10:35:04 AM »
That's some amazing demonstration, Jay. Thanks for that!

Pmt, thanks for your answer. :)

ajouis

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Re: The 2020 melting season
« Reply #2567 on: July 11, 2020, 10:55:54 AM »
way back when there was 10 year-old.

That was before my time, Pmt! ;)

Do you know, what's causing 10yo ice to appear blue? I mean, sea ice is not constantly under pressure, which causes the glacier ice to develop its bluish tint.
My guess would be the freshening of old ice by salt extrusion, and the layers built in successive winters.
Pressure is not what’s needed for obtaining blue ice but several freeze thaw cycles, which is why it is usually the upper layer just after the melt crust that is blue. My guess is that the conditions are even more thaw freeze cycles for ice from salted water, which is why you need that much more time, plus the conditions might be more uniform, being conducive to either solely melt or freeze, because of the constant sun that doesn’t allow a great day gradient. You can however see that refrozen meltponds are slightly bluer
After a thousand steps on the ice, it cracked.
The Man looked down at the infinite blue of the sea.
On the horizon, standing still, the polar bear had just scented his next meal.

 Less than 3000 cubic kilometers this Piomas minimum.

blumenkraft

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Re: The 2020 melting season
« Reply #2568 on: July 11, 2020, 11:10:44 AM »

Pressure is not what’s needed for obtaining blue ice but several freeze thaw cycles,

Ouch, i didn't know that. Interesting!

Quote
You can however see that refrozen meltponds are slightly bluer

True! Thanks for the hint, Ajouis. :)

ajouis

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Re: The 2020 melting season
« Reply #2569 on: July 11, 2020, 11:19:19 AM »
You’re welcome Blumenkraft  :) it’s easier to know when you’re from an ice climbing background since most ice that is formed in a non glacier environment is from freeze and thaw, on the other hand I didn’t know that glaciers were created by compression until a couple years ago, so you win some, you lose some
After a thousand steps on the ice, it cracked.
The Man looked down at the infinite blue of the sea.
On the horizon, standing still, the polar bear had just scented his next meal.

 Less than 3000 cubic kilometers this Piomas minimum.

JayW

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Re: The 2020 melting season
« Reply #2570 on: July 11, 2020, 11:25:05 AM »
You’re welcome Blumenkraft  :) it’s easier to know when you’re from an ice climbing background since most ice that is formed in a non glacier environment is from freeze and thaw, on the other hand I didn’t know that glaciers were created by compression until a couple years ago, so you win some, you lose some
"Bluing" of ice crystals is a result of going from smaller to larger crystals. The larger the crystal, the more red light is absorbed.
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Jontenoy

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Re: The 2020 melting season
« Reply #2571 on: July 11, 2020, 11:37:06 AM »
12.3 C  Sea Surface temp anomaly at exit of Lena River.... Not good !

blumenkraft

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Re: The 2020 melting season
« Reply #2572 on: July 11, 2020, 11:46:50 AM »
"Bluing" of ice crystals is a result of going from smaller to larger crystals. The larger the crystal, the more red light is absorbed.

I'm glad we had this talk. This keeps giving.  ;D

pauldry600

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Re: The 2020 melting season
« Reply #2573 on: July 11, 2020, 12:01:31 PM »
It's all not good but I make this mistake every year thinking it will finish in September under 3 million.

Surely this year is definitely a below 4 million year and that is the new trend. All the next 5 to 10 years will be in the 3s with perhaps the odd one in the early 4a.

I'm sticking to it ending at 3.9m so there is 3.7m melt left to go.

Some places start to get colder from late July so that is my rationale even though most here expectva record year. Arctic you wont fool me.....or I'm the fool.

JayW

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Re: The 2020 melting season
« Reply #2574 on: July 11, 2020, 12:07:37 PM »
925mb temperature anomaly for the first 8 days of July.
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ArcticMelt2

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Re: The 2020 melting season
« Reply #2575 on: July 11, 2020, 12:11:15 PM »
Today’s image of the northern coast of Taimyr. Two narrow ice barriers are the last thing that separates the NorthEastern passage from full opening. 20 days earlier than in 2012.

Pagophilus

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Re: The 2020 melting season
« Reply #2576 on: July 11, 2020, 12:13:00 PM »
Yesterday, Worldview, contrast heavily tweaked on Photoshop.

Chukchi on left with only remnants of very brown ice, ESS ice looking increasingly fragile and scattered...
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Pagophilus

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Re: The 2020 melting season
« Reply #2577 on: July 11, 2020, 12:48:33 PM »
Thank you.  The icecap edge seems to be aligning remarkably closely with the 200m submarine contour.  Coincidence maybe, but it means, IMHO, that the conversation here should include what is happening with waters beneath the ice more extensively than our replies do now.

Welcome, Pagophilus. :) I'm trying to find out in which part this is caused by bathymetry and which by atlantification. And those two variables are somehow interconnected insofar that the warm water coming from the south is descending into the depth of the Arctic basin here.

Moah data needed...

BTW, this is the site that provided the data for this GIF >> https://oden.geo.su.se/map/

Thank you for the site, Blumenkraft -- really intriguing and useful.  I guess I was more blown away by the close overall correspondence of the current ice with the bathymetry.  The exceptions are the now wispy, failing ESS and the unusual case of the CAA (which is all fast ice I believe).  The concentrated sea ice via AMSR2 is almost an overlay of the deep Arctic Ocean waters.  Perhaps nothing new to experts, but it is amazing to me.

Looking back over the site you gave above, it seems as if this is the case almost every mid July.  The exception is that in some years there is more ice melted out in the Beaufort than this year, and this means open waters there above that deep Arctic basin. 

This year one area where this does not seem to hold is the Laptev, which we know is anomalously very warm.  Here the ice has melted out above the deep Arctic Ocean.  So is this always about warm saline waters plunging below the cold freshwater just below the ice?  Does the intense ice melting during July provide some of that protective cold freshwater (cold for a while) and produce this pattern?  In other words, does the ice insulate itself from heat from below in this way at this time of year?

Just musings, really.  I know this is a whole science in itself, with currents as well as density differences.   
« Last Edit: July 11, 2020, 01:04:57 PM by Pagophilus »
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Comradez

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Re: The 2020 melting season
« Reply #2578 on: July 11, 2020, 04:13:51 PM »
Wow, GFS, ECMWF, and Nullschool all agree on the Great Arctic Anti-Cyclone (GAAC) sticking around for at least another week, albeit weakening somewhat.  In addition, the backside of the GAAC in the Chukchi and ESS is slated to have cooler air aloft (850 mb at -5C) and chilly temperatures at the surface (as low as -0.5C), so there may be some surface refreezing there.  But it is also slated to have very strong winds, so it may not be great for the slushy ice there anyways, sitting adjacent to some 2C water and with upwelling likely from the choppy seas. 

And then on the front side (Laptev/Kara front), the warm air aloft (5C) and surface temps (1C) are going to be replenished from a warm air mass coming off of the Taymyr Peninsula.  There will also be very strong winds here.  We may actually see the Atlantic ice front really crumble beyond the continental shelf line in a big way for the first time in recorded history this summer, if this consistent southerly fetch from the GAAC keeps up. 

Also, the Beaufort is slated to have cool air aloft (as the cool backside of the GAAC develops towards the Chukchi), but then followed a few days later by gentle warm southerly winds coming off the Mackenzie Delta and clear skies. 

The CAA looks like it will have good conditions for melting throughout.  The recent slowdown in area drops probably has to do with melt ponds draining here.  The ice in a lot of the channels is transitioning to a very thin grayish appearance (Tanquary fiord on Ellesmere Island is a good example of this).  Once that benchmark is reached, expect full melt-out 2-3 weeks later. 

And finally, Hudson Bay and Baffin Bay are doing their usual thing.  Not late or early, and looking quite irrelevant to the melt in the rest of the arctic.  Ice will be gone in these spots by Aug. 1st.  Expect that to factor into some big area & extent drops. 

BornFromTheVoid

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Re: The 2020 melting season
« Reply #2579 on: July 11, 2020, 04:41:53 PM »
Latest NSDIC daily extent shows a big drop again, 176k. That's 2 mega melt weeks in a row, 2.015 million km2 lost in 2 weeks.

Below is the latest projection up to the end of September, and an animation of how that has changed over the last 4 days below that.



I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

RoxTheGeologist

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Re: The 2020 melting season
« Reply #2580 on: July 11, 2020, 07:36:27 PM »
RE: #2478 bathymetry

Love this post blumenkraft!  Are you trying to point out the similarity in the boundary between the deep Arctic Basin and the boundary of the minimum each year, there is certainly a relationship.




There is definitely a relationship. Can be overcome, but not easy. WAA from Siberia or NAM will overcome some of it and endless compaction could do the trick on the Atlantic side.

The match-up between the ice age and the bathymetry was even more pronounced during 2016!

https://forum.arctic-sea-ice.net/index.php/topic,382.msg84085.html#msg84085


Pagophilus

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Re: The 2020 melting season
« Reply #2581 on: July 11, 2020, 10:10:03 PM »
What a difference a week makes...

Ice in ESS and Chukchi, July 4 and July 11, Worldview

The images are about 1400km, approaching 1000 miles, across.
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Phoenix

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Re: The 2020 melting season
« Reply #2582 on: July 11, 2020, 10:37:48 PM »
Latest NSDIC daily extent shows a big drop again, 176k. That's 2 mega melt weeks in a row, 2.015 million km2 lost in 2 weeks.

Yes, the declines have been exceptional. The allocation of the decline between "mega melt" and compaction isn't completely clear. PIOMAS will provide one perspective on that in another week or so.

be cause

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Re: The 2020 melting season
« Reply #2583 on: July 11, 2020, 10:49:15 PM »
pretty much every forecaster agrees .. the GAAC is here to stay another week at least . The latest gfs has it slipping away in 15 days . The basin of ice is set to keep spinning and shrinking . The winds are looking stronger , with easterly gales from the Bering to the Fram north of Eurasia over the next few days.
  I see more and more ice ready to go the way of Kara's brown ice which is now mostly gone . Pagophilus's brown ice in Chukchi extends by degrees well into the CAB , ready to collapse before tide , wind wave and current  . None of the ice from Chukchi to the Atlantic has what it takes to get to winter . It may not have what it takes to get to August !
As johnm33 posted earlier on the hycom thread the remaining ice has lost the capacity to crack at any significant scale . It is clearly not becalmed ! 
https://media.giphy.com/media/l0FQB0AZDXG4ISsj5U/giphy.gif

Nothing to stop top and bottom melt continuing apace .. plenty more sun and momentum .
as the hycom gif shows , we pretty much have 2/3rds of the CAS exposed to open water .
 
The CAA- Greenland mega crack is doing fine .. a few thousand sq kms of warming water where there was always multiyear ice in the past . btw .. Did anyone notice the 10 mile cube of ice balanced above Ellesmere on the latest worldview ? Yesterday offered fine views of the  N. Greenland Sea .
 The ice in Lincoln is on the move .. with the GAAC easterly , most of it seems intent on heading for Beaufort at @ 10 km /day though the ice N. of Ellesmere has travelled 60 km in the last 3 days . Some of this ice may make it to the refreeze .
 2020 is fast becoming a vision of the future .. b.c.

2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 + 2 = 2021 
 (phew)

grixm

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Re: The 2020 melting season
« Reply #2584 on: July 11, 2020, 10:52:01 PM »
Fun fact: If my calculations are correct then the current rotation of the central basins sea ice due to the anticyclone carries about 2E13 joules of kinetic energy. This must be eventually converted to heat for the rotation to stop, which is enough to melt 60 000 cubic meters of ice. This might sound significant at first but actually it is just the equivalent of around 10 nanometers of ice thickness across the arctic.

Pagophilus

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Re: The 2020 melting season
« Reply #2585 on: July 11, 2020, 11:06:43 PM »
Fun fact: If my calculations are correct then the current rotation of the central basins sea ice due to the anticyclone carries about 2E13 joules of kinetic energy. This must be eventually converted to heat for the rotation to stop, which is enough to melt 60 000 cubic meters of ice. This might sound significant at first but actually it is just the equivalent of around 10 nanometers of ice thickness across the arctic.

Thank you for making me laugh out loud for several minutes.  I had been gloomily contemplating the current state of the ice, and you made me feel a lot better.  If I could give you a 100 likes, I would!
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PragmaticAntithesis

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Re: The 2020 melting season
« Reply #2586 on: July 11, 2020, 11:09:56 PM »
Fun fact: If my calculations are correct then the current rotation of the central basins sea ice due to the anticyclone carries about 2E13 joules of kinetic energy. This must be eventually converted to heat for the rotation to stop, which is enough to melt 60 000 cubic meters of ice. This might sound significant at first but actually it is just the equivalent of around 10 nanometers of ice thickness across the arctic.

Just goes to show the sheer amount of energy it takes to melt out such a significant portion of the ice volume. Humanity's impact on the climate has been rather severe already!
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Comradez

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Re: The 2020 melting season
« Reply #2587 on: July 11, 2020, 11:18:54 PM »
60,000 cubic meters of ice would be a slab 1m thick x 0.1km wide x 0.6km long.  Barely big enough to show up as multiple pixels on worldview. 

Greenbelt

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Re: The 2020 melting season
« Reply #2588 on: July 11, 2020, 11:29:35 PM »
The ten mile cube north of Elsemere Island today and July 7. The slice just the east on july 7 seems now to the north (and smaller)

jdallen

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Re: The 2020 melting season
« Reply #2589 on: July 11, 2020, 11:33:17 PM »
What a difference a week makes...

Ice in ESS and Chukchi, July 4 and July 11, Worldview

The images are about 1400km, approaching 1000 miles, across.
Judging from condition, virtually *all* of the ice in the 7/11 image is doomed, and will likely be gone by August 1 without massive intervention by the weather.
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gandul

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Re: The 2020 melting season
« Reply #2590 on: July 12, 2020, 12:02:18 AM »
Latest NSDIC daily extent shows a big drop again, 176k. That's 2 mega melt weeks in a row, 2.015 million km2 lost in 2 weeks.

Yes, the declines have been exceptional. The allocation of the decline between "mega melt" and compaction isn't completely clear. PIOMAS will provide one perspective on that in another week or so.

It’s been a mega melting although I think there’s been some braking in the last days and probably next week area won’t drop beyond average. Extent should continue dropping faster than average. Compaction helps the central CAB ice at this point though, but the periphery is done, including the Beaufort sea which doesn’t look that solid to me after all.
The question is, what will happen in August with an almost CAB-only pack left? Will August be less boring than 2019? Will cold boring weather and bathymetry limit further extent losses or will a messy weather be able to disperse and break the boundaries of 2012?

Phoenix

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Re: The 2020 melting season
« Reply #2591 on: July 12, 2020, 01:11:56 AM »
..... the periphery is done, including the Beaufort sea which doesn’t look that solid to me after all.


Beaufort is 7 weeks behind the 2019 SIA pace. We're 3 weeks post solstice and things are going to start cooling off before long. 10 day forecast is moderate with scattered sub zero temps. Seems like the window is closing and imagine something like 300-400k km2 at the minimum. Even 450k km2 seems in the realm of possibility.

The rotation is picking up and the floes are spreading apart, but there isn't much warm SST to capitalize on that and not much time to develop those SST's.

Freegrass

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Re: The 2020 melting season
« Reply #2592 on: July 12, 2020, 01:52:25 AM »
Latest Five Day Forecast + Last 24 Hours
Wind @ Surface

Large GIF!

I haven't posted a forecast for a few days now due to "birthday celebration complications", so I've added the last 24 hours in this forecast.

It's not looking good for the ice north of Laptev near SZ. This ice lasted until the end of the season in 2019. This year there won't be much left it seems.

The wind above the CAA and Greenland will cause the mega crack to grow larger, and will free up the ice from resistance against the land, allowing the entire ice pack to spin more freely I think.

Fram export will continue, and the Lincoln sea is draining, but I wonder how much methane clathrates will be released this year. All that wind over the ESS and Laptev must be mixing up the water there pretty good while the sun keeps beating down on it. So what is that doing to the clathrates?
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Rod

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Re: The 2020 melting season
« Reply #2593 on: July 12, 2020, 01:54:46 AM »
Latest NSDIC daily extent shows a big drop again, 176k. That's 2 mega melt weeks in a row, 2.015 million km2 lost in 2 weeks.

Yes, the declines have been exceptional. The allocation of the decline between "mega melt" and compaction isn't completely clear. PIOMAS will provide one perspective on that in another week or so.

NSIDC posts its maps everyday. You can compare from one day to the next to see where the losses are occurring. 

PIOMAS won’t tell you anything about NSIDC extent data. They are two completely different tools that provide very different information.
« Last Edit: July 12, 2020, 02:14:16 AM by Rod »

Freegrass

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Re: The 2020 melting season
« Reply #2594 on: July 12, 2020, 02:04:05 AM »
Latest Five Day Forecast
Wind @ 250hPa

Large Gif!

It appears the GAAC is just getting settled in...
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JNap

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Re: The 2020 melting season
« Reply #2595 on: July 12, 2020, 02:13:54 AM »
If the GAAC continues as forecast by GFS and ECM, then the trajectory for the Laptev sea suggests that it will completely melt by ~Aug 1st.

https://twitter.com/ZLabe/status/1282013902159491073/photo/1
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Pagophilus

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Re: The 2020 melting season
« Reply #2596 on: July 12, 2020, 03:20:06 AM »
Latest Five Day Forecast + Last 24 Hours

I haven't posted a forecast for a few days now due to "birthday celebration complications", so I've added the last 24 hours in this forecast.


Very useful animation, as ever, Freegrass.  Thank you.  If it was your birthday -- Happy Birthday! 

Cross-posting this from the area and extent thread from JNap, as it gives a sobering message that is germane to the continuing weather forecast...

Here is a yearly extent comparison since 2000 for the period each year from June 27 - July 10 using NSIDC data. 

The GAAC that has been occurring during a near peak insolation period has made 2020 the leader for both total extent reduction as well as the percentage of extent reduction during this past 13 day period.

Year   Melt Total (000's)   % of Ice Melted during period
2000   1.015   9.4%
2001   0.886   8.2%
2002   1.078   9.7%
2003   1.015   9.4%
2004   0.886   8.2%
2005   1.200   11.5%
2006   1.207   12.0%
2007   1.808   17.4%
2008   1.078   10.4%
2009   1.596   15.0%
2010   0.890   9.4%
2011   1.479   15.2%
2012   1.548   16.0%
2013   1.730   16.6%
2014   1.529   15.2%
2015   1.203   11.7%
2016   1.141   11.8%
2017   1.258   12.7%
2018   1.124   11.1%
2019   1.664   17.2%
2020   1.993   20.2%
« Last Edit: July 12, 2020, 03:53:29 AM by Pagophilus »
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Pagophilus

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Re: The 2020 melting season
« Reply #2597 on: July 12, 2020, 03:34:53 AM »
Compaction helps the central CAB ice at this point though, but the periphery is done, including the Beaufort sea which doesn’t look that solid to me after all.

Not sure I would agree with this statement about the Beaufort, gandul.  It looks more ice-covered and more densely packed with ice than in many recent years to me.  Admittedly the ice seems mostly fragmented floes packed tightly together, but that has generally been the case in July. Perhaps there is something I am not seeing.  Image from Worldview, contrast highly tweaked to bring out features.. 
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Phoenix

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Re: The 2020 melting season
« Reply #2598 on: July 12, 2020, 05:37:37 AM »
One interesting feature of the GAAC is the difference in impact at the surface and in the air just above the surface.

At the surface, we see ice contracting over an area measured in millions of square kilometers. The vast majority of the basin ice is moving in the direction of the center of a gigantic gyre.

Just above the surface, the air gyre at the center is ~ an order of magnitude smaller than the surface gyre. The center of the air gyre has maintained a core of warm air that existed at the onset of the GAAC while the area around the that core has gradually had an warm air pushed out of the basin and lower latitude WAA has been blocked from entering the basin.

Due to it's central location, that consistent warm air mass at the center of the gyre has been providing turbo melt (above and beyond the insolation) in the most vulnerable portion of the CAB adjacent to the Laptev in the 80-85N range.

The best way to illustrate the phenomena is to look at the minimum temperature forecast for the Arctic. It's extremely uncommon to see a chart where the highest minimums over the ice covered areas are centered N of 80N while lower latitudes go colder. But such is the impact of le' GAAC. Take a look at the 5 day day chart....

https://climatereanalyzer.org/wx/fcst_outlook/

Going forward, there is a reduction of the warm area at the center of the GAAC. Also movement toward the Pacific which can be seen in the difference in the 5 day above and the 10 day below.

https://climatereanalyzer.org/wx_frames/gfs/ds/gfs_arc-lea_t2min_10-day.png


gandul

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Re: The 2020 melting season
« Reply #2599 on: July 12, 2020, 06:05:19 AM »
Compaction helps the central CAB ice at this point though, but the periphery is done, including the Beaufort sea which doesn’t look that solid to me after all.

Not sure I would agree with this statement about the Beaufort, gandul.  It looks more ice-covered and more densely packed with ice than in many recent years to me.  Admittedly the ice seems mostly fragmented floes packed tightly together, but that has generally been the case in July. Perhaps there is something I am not seeing.  Image from Worldview, contrast highly tweaked to bring out features..

Yes perhaps I’m wrong about Beaufort. But what Beaufort ice really resents is a couple of good storms to disperse all that ice and accelerate bottom melt, ice floe fragmentation and lastly meltout by bottom and lateral melt and wave washout, and the same for whatever ice remains in August in the Arctic.