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Paul

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Re: The 2020 melting season
« Reply #5650 on: September 01, 2020, 12:31:18 PM »
Well I expected a 2nd place in extent but due to more of the Beaufort ice melting out rather than a sharp retreat of the Atlantic edge. Really impressive stuff I must say.

I think those hoping the Beaufort will melt out will probably be disappointed, temperatures actually look more cooler(or normal!) here than the pole and with sea ice recently melted there, I still expect a fast refreeze aslong as weather plays ball locally there. Might be the only positive from this melt season really, if the ice does survive then we may see an arm of more 2nd year ice heading across towards the Chukchi as we head through winter.

I have no idea how long it will take for the Laptev sea to freeze over, bound to be record breaking and with such a sharp retreat in the Atlantic edge, it could be very hard for the Laptev to freeze over until we see the 'doors' of the Atlantic and Pacific waters being closed by 'ice arms' into the ESS and Kara seas respectively.

How low will this year go, I suspect a bit lower with more retreat on the ice in the Laptev, weather conditions look favourable for this.

Freegrass

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Re: The 2020 melting season
« Reply #5651 on: September 01, 2020, 02:14:37 PM »
Latest Five Day Forecast
Wind @ Surface
Wind + Temp @ 850hPa
Wind @ 250hPa
Large GiFS!
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Killian

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Re: The 2020 melting season
« Reply #5652 on: September 01, 2020, 02:40:10 PM »
Speaks for itself.

dnem

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Re: The 2020 melting season
« Reply #5653 on: September 01, 2020, 02:44:17 PM »
It's hard to believe there's no online tool where you can overlay multiple years of the DMI north of 80 graphic.

igs

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Re: The 2020 melting season
« Reply #5654 on: September 01, 2020, 02:58:12 PM »
Well I expected a 2nd place in extent but due to more of the Beaufort ice melting out rather than a sharp retreat of the Atlantic edge. Really impressive stuff I must say.

I think those hoping the Beaufort will melt out will probably be disappointed, temperatures actually look more cooler(or normal!) here than the pole and with sea ice recently melted there, I still expect a fast refreeze aslong as weather plays ball locally there. Might be the only positive from this melt season really, if the ice does survive then we may see an arm of more 2nd year ice heading across towards the Chukchi as we head through winter.

I have no idea how long it will take for the Laptev sea to freeze over, bound to be record breaking and with such a sharp retreat in the Atlantic edge, it could be very hard for the Laptev to freeze over until we see the 'doors' of the Atlantic and Pacific waters being closed by 'ice arms' into the ESS and Kara seas respectively.

How low will this year go, I suspect a bit lower with more retreat on the ice in the Laptev, weather conditions look favourable for this.

I didn't see one single post claiming that the beaufort will melt out recently, while some users, including myself, predict that MOST of the current is doomed and that a few larger floes will survive.

If you follow development carefully you can see that beaufort is losing either extent and/or concetration quite rapidly and significantly each single day and I've seen some heavy winds from the east forecasted and that will kill half of that because it's currently between 15 and 20% concentration.

Further you say that Beaufort will be mostly responsible for further losses, which in fact is the same that I'm saying, that there will be significant losses, on the other hand you deny the daily retreat on the laptev and especially atlantic side that currently accounts not only for the bigger part of today's losses, but is forecasted to maintain the pattern and even getting worse with a slight shift towards laptev.

Should the longer term forecasts, which, as we know, are not reliable and rarely come true, materialize, the Russian side of ESS and Laptev will heat up one last time and provide another nasty blow.

Basically what @Oren said recently, it will most probably be an extended season, meathing 2012 around equinox but miss it by a (relatively) small margin.
« Last Edit: September 01, 2020, 03:04:39 PM by igs »

SimonF92

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Re: The 2020 melting season
« Reply #5655 on: September 01, 2020, 03:29:16 PM »
It's hard to believe there's no online tool where you can overlay multiple years of the DMI north of 80 graphic.

Zack Labe has done a pretty good job of that (granted you cant select individual years);

https://sites.uci.edu/zlabe/arctic-temperatures/
Bunch of small python Arctic Apps:
https://github.com/SimonF92/Arctic

ArcticMelt2

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Re: The 2020 melting season
« Reply #5656 on: September 01, 2020, 03:29:51 PM »
In the Laptev Sea, 2020 finally took a new absolute record.  :'(

1. 2020    379 km2
2. 2014    887 km2
3. 2018   9031 km2
4. 2013  11830 km2
5. 2011  14157 km2
6. 2012  21509 km2

Shared Humanity

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Re: The 2020 melting season
« Reply #5657 on: September 01, 2020, 03:38:07 PM »
How different  could the arctic of 2012 be? Ice volume is the same as now

The Arctic is much thinner and more fragmented while holding more thermal energy than before.

Additionally new melt fronts such as Northern Greenland, and shifting locations of the remaining bastions of ice, including the western migration of the MYI pack towards the Beaufort also seem to be significant departures from the Arctic of the past.

I agree. 

The single biggest difference in the ice between 2012 and 2020 is how fragmented and mobile it is. The days of large rhomboids of thick ice hugging the CAA and Greenland at the end of the melt season are long gone, never to return. The thick ice now exported to the Beaufort has little in common with the ice that formerly drifted there to protect the CAB.

Shared Humanity

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Re: The 2020 melting season
« Reply #5658 on: September 01, 2020, 03:48:46 PM »
Today's images and slow animation (slightly larger version on twitter)...

The drop in concentration in the Beaufort in the last 24 hours is somewhat concerning.

Shared Humanity

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Re: The 2020 melting season
« Reply #5659 on: September 01, 2020, 03:57:04 PM »
In the Laptev Sea, 2020 finally took a new absolute record.  :'(

1. 2020    379 km2
2. 2014    887 km2
3. 2018   9031 km2
4. 2013  11830 km2
5. 2011  14157 km2
6. 2012  21509 km2

Given the weather pattern for the next 5 days, that side of the CAB will continue to drop, dramatically in my opinion.

aslan

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Re: The 2020 melting season
« Reply #5660 on: September 01, 2020, 04:05:19 PM »
Today's images and slow animation (slightly larger version on twitter)...

The drop in concentration in the Beaufort in the last 24 hours is somewhat concerning.

Easterlies and waves are probably hitting the Beaufort sea. Winds up to 30kt from the east, for the southern part of the arm of ice :

http://ogimet.com/cgi-bin/gsynres?ind=71948&decoded=yes&ndays=20&ano=2020&mes=09&day=01&hora=15

And models are showing waves of up to 3 meters with a period of up to 7 seconds. It is not the big washing, but way enough for some floes to go "poof".

Freegrass

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Re: The 2020 melting season
« Reply #5661 on: September 01, 2020, 05:18:56 PM »
3.71 in data from the University of Bremen.

https://www.meereisportal.de/en/
Does this image end the debate about bathymetry and the ice edge? The ice edge clearly doesn't care about bathymetry...
That is interesting. Usually, the periphery area such as Beaufort sea, East Siberian sea and Laptev sea are part of the continental shelf. Therefore, the sea water is much more easier to be heated in summer and temperature will rise relatively fast. The Arctic Basin is much deeper thus the sea water will not be heated so fast to melt the ice. The most interesting thing is that although the Arctic Basin is slow to be heated, it has more thermal capacity to trap more heat through the winter. The continental shelf region is easy to be heated meanwhile easy to be cooled when autumn comes.
I think peripheral seas - aka continental shelves - melt out first because they receive first sunlight on freshly produced ice.

It took me a while to get it into my stubborn brain, but it's all about the salt. Salinity is way more important than any other factor. I'm hope Uniquorn agrees with me on that. The end result of a melting season completely depends on the weather. Salinity dictates the ice edge, not bathymetry.

I really hope I'm right about this...  :-\
« Last Edit: September 01, 2020, 05:41:27 PM by Freegrass »
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gandul

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Re: The 2020 melting season
« Reply #5662 on: September 01, 2020, 05:38:14 PM »
Yeah baby, like there’s no relationship between salinity and bathymetry.

BornFromTheVoid

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Re: The 2020 melting season
« Reply #5663 on: September 01, 2020, 05:43:56 PM »
A side by side comparison of the NSIDC daily extent and AMSR2 concetration over the last 2 months (quite a big file, click to play)
Better quality version on twitter here: https://twitter.com/Icy_Samuel/status/1300821056131923969
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

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Re: The 2020 melting season
« Reply #5664 on: September 01, 2020, 06:13:01 PM »
That's really great BornFromTheVoid, many thanks.

A question, could you make a version that's much slower? And/or mark the loss per week with a colour? For me, that would mean even more information.
Your placing of dates and legenda & scale, and synchronising with the frames, and used font are also very good imo. You know your way around your tools :).
You have been a super visualizer and help for me.
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Freegrass

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Re: The 2020 melting season
« Reply #5665 on: September 01, 2020, 06:15:10 PM »
Yeah baby, like there’s no relationship between salinity and bathymetry.
I don't see any relation at the surface in the images I posted. The only relation I see is with the current ice edge.
« Last Edit: September 01, 2020, 06:39:30 PM by Freegrass »
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BornFromTheVoid

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Re: The 2020 melting season
« Reply #5666 on: September 01, 2020, 06:24:39 PM »
That's really great BornFromTheVoid, many thanks.

A question, could you make a version that's much slower? And/or mark the loss per week with a colour? For me, that would mean even more information.
Your placing of dates and legenda & scale, and synchronising with the frames, and used font are also very good imo. You know your way around your tools :).
You have been a super visualizer and help for me.

Cheers.
I think I get what you mean. Will try put a version of that together this evening.
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gandul

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Re: The 2020 melting season
« Reply #5667 on: September 01, 2020, 06:42:30 PM »
Yeah baby, like there’s no relationship between salinity and bathymetry.
I don't see any relation.
This year is the best example. the CAB has received the insolation of the century, same insolation was terminal in Laptev, ESS, very rapidly. The CAB has stayed over zero since July, plenty of surface melt. Really warm conditions. The Polrstern has found a sea of melt ponds at the NP (“fractional ice”). But will survive.
Just look at the maps, the bathymetry, the salinity, the ice extent maps.
But well if you don’t see it I am not going to insist.

Freegrass

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Re: The 2020 melting season
« Reply #5668 on: September 01, 2020, 07:07:24 PM »
Yeah baby, like there’s no relationship between salinity and bathymetry.
I don't see any relation.
This year is the best example. the CAB has received the insolation of the century, same insolation was terminal in Laptev, ESS, very rapidly. The CAB has stayed over zero since July, plenty of surface melt. Really warm conditions. The Polrstern has found a sea of melt ponds at the NP (“fractional ice”). But will survive.
Just look at the maps, the bathymetry, the salinity, the ice extent maps.
But well if you don’t see it I am not going to insist.
What I saw this year is an ice pack that rotated counterclockwise right before melting season started. This opened up a gap near the Severnaya Zemlya islands. This gap absorb a lot of insolation and created the laptev bite we see today. But there's one part that didn't melt out, north of the New Siberian Islands, and that matches exactly with the spot where the influx of salt Atlantic waters and salty Bering sea waters end.

That spot is also close to the first open water north of the New Siberian Islands,  but still hasn't melted out. Why is that?

And doesn't this happen almost every year, if a storm doesn't mess it up?
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Freegrass

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Re: The 2020 melting season
« Reply #5669 on: September 01, 2020, 08:05:40 PM »
Latest Five Day Forecast
Wind @ Surface + Total Precipitable Water
Large GiF!
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FishOutofWater

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Re: The 2020 melting season
« Reply #5670 on: September 01, 2020, 08:09:25 PM »
The Barents and Kara seas were stormy (low pressure) last winter. That advected Atlantic water into those seas and those same winds compacted floes of ice on the New Siberian islands. The very thick piles of ice that built up in winter have been very slow to melt out despite the heat and warm water this summer. It's an anomaly that doesn't have much significance when you look at the big picture in the Arctic this summer.

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Re: The 2020 melting season
« Reply #5671 on: September 01, 2020, 08:23:08 PM »
In the Laptev Sea, 2020 finally took a new absolute record.  :'(

1. 2020    379 km2
2. 2014    887 km2
3. 2018   9031 km2
4. 2013  11830 km2
5. 2011  14157 km2
6. 2012  21509 km2
EDIT>>> What data are you quoting? (It certainly isn't NSIDC 5 day trailing average)
« Last Edit: September 01, 2020, 08:37:05 PM by gerontocrat »
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UCMiami

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Re: The 2020 melting season
« Reply #5672 on: September 01, 2020, 08:24:41 PM »
How about:
1. High salinity increases ice melt
2. Warmer water increases ice melt
3. Large amounts of ice melting lowers both temperature and salinity of the surrounding water.
4. Shallow continental shelves allow Atlantic and Pacific ocean incoming currents (higher salinity and higher temperature) to remain in contact with ice while deeper ocean floors and continental shelf drop offs allow those same currents to flow under the upper less dense, less saline and colder surface layer.
5. Surface turbulence (caused by wind/ice movement) will have a greater mixing effect in shallow water than in deep water.
6.Shallow water will also heat more quickly regardless of incoming water than deeper water. And open shallow water will also increase in salinity because of surface evaporation.
7. Arctic shallow water is also almost entirely south of 80N latitude which means it is closer to both Atlantic and Pacific entry points, and is exposed to greater isolation earlier and for longer than deeper Arctic waters.

Conclusion - Salinity, Atlantic and Pacific currents, isolation, bathymetry, turbulence (weather), latitude, and warm/cold landmasses (air masses) all play a significant and varied roll in every melt season. Add in the preceding freezing seasons and the volume/area/extent of the ice pack and maybe we could predict the ending point of each melt season.

(Need a big computer, better measurements, and brilliant programers and we are all set.)
« Last Edit: September 01, 2020, 08:53:29 PM by UCMiami »

BornFromTheVoid

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Re: The 2020 melting season
« Reply #5673 on: September 01, 2020, 08:34:09 PM »
That's really great BornFromTheVoid, many thanks.

A question, could you make a version that's much slower? And/or mark the loss per week with a colour? For me, that would mean even more information.
Your placing of dates and legenda & scale, and synchronising with the frames, and used font are also very good imo. You know your way around your tools :).
You have been a super visualizer and help for me.

Unfortunately I don't have time to do the animation this evening. But hopefully an image will suffice for now!
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

gerontocrat

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Re: The 2020 melting season
« Reply #5674 on: September 01, 2020, 08:46:20 PM »


Conclusion - Salinity, Atlantic and Pacific currents, isolation, bathymetry, turbulence (weather), latitude, and warm/cold landmasses (air masses) all play a significant and varied roll in every melt season. Add in the preceding freezing seasons and the volume/area/extent of the ice pack and maybe we could predict the ending point of each melt season.

(Need a big computer, better measurements, and brilliant programers and we are all set.)
" the volume/area/extent of the ice pack" - we don't even know the condition of the ice-pack. PolarStern proved that by chugging along at 5 to 7 knots at 88 North.

Look at this year - 2019 came in at #2, and the winter freeze was well above average. Conventional wisdom said a pretty ordinary 2020 melting season was in store. Huh.

but then again, UCMiami - you know that very well, you tease, you.
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Re: The 2020 melting season
« Reply #5675 on: September 01, 2020, 09:18:22 PM »
Its clear as day that there is a major correlation between bathymetry and the ice edge.


It is much harder to melt ice over the super deep parts of the Arctic
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Freegrass

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Re: The 2020 melting season
« Reply #5676 on: September 01, 2020, 09:54:51 PM »
Does this image end the debate about bathymetry and the ice edge? The ice edge clearly doesn't care about bathymetry...
I didn't know there still was a debate about bathymetry. I seem to remember having started just such a debate a few years ago, and after much heated argumentation and wild claims, I believe the real physics behind any link between the ice edge and bathymetry was teased out.

And the only area where I was convinced that bathymetry had a real effect was where the warm Atlantic waters get room to sink once they are past the Svalbard / FJL line. Another real effect is the shallowness of the Siberian seas, which makes water movement much less pronounced but are too shallow to have proper stratification, hence rapid and extensive mixing once ice-free.

But these are secondary effects. There is no primary effect between bathymetry and the ice edge, and since a lot of other factors come into play as well, any link with bathymetry can only be considered transitory and weak.
I'm with Binntho on this. And I want to add that I think that ice over the deepest parts of the arctic remains frozen longer because it is located closer to the pole.

Right now there's ice left over shallow parts north of the New Siberian islands, and last year the Beaufort ice was some of the first ice to melt out. So there's goes that theory...

I agree that bathymetry causes salt water to drop off into the deep on the Atlantic and Chukchi side, but I do believe that salinity is way more important to determine the eventual ice edge compared to bathymetry. And as can be seen on the salinity map I posted, salinity doesn't follow bathymetry everywhere. And if you post the current remainder of the ice over bathymetry, or salinity, I think salinity will define the ice edge much better.

But what do I know? I'm just trying to get a good debate going here because that's completely missing from the melting thread this year...   :'(

PS; And in normal years, ice in the ESS is the last to melt out. If I'm not mistaken, the shallowest shelf in Arctica. But saltless...
« Last Edit: September 01, 2020, 10:19:30 PM by Freegrass »
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Re: The 2020 melting season
« Reply #5677 on: September 01, 2020, 10:19:10 PM »
The 12Z euro has a really consistent narrow wind field that goes nearly perpendicular to the ice edge between the Atlantic side and Laptev.

The ice here is breaking down already inside the ice edge between 85-88N. 

Iirc this is directly over the Laptev bite..

This area could lose quite a bit of ice coverage by the 6-7th.



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Neven

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Re: The 2020 melting season
« Reply #5678 on: September 02, 2020, 12:40:41 AM »

I’d hypothesize the major difference is that 2012 took some pretty extreme weather in a perfect setup to get where it was which also consequently released a lot of the absorbed energy possibly resulting in the 2013-2014 rebound. 2019 was not followed by a rebound and 2020 does not look quite likely to be either, so I think the difference lies in position regarding the overall trend, and the fact that this “extraordinary looking” melt season isn’t really all that out of the ordinary, especially compared to 2012 in its time. Next year could quite easily compound on this year further and maybe even pass 2012 while being plausibly expected instead of being a moonshot. The Arctic is much thinner and more fragmented while holding more thermal energy than before.

A very nice and concise summary of this year's melting season and what it may portend for the future. Thanks.

And it's not entirely over yet, when looking at the ECMWF forecast. That pressure gradient is going to do a real number on the ice north of Severnaya Zemlya. It's amazing what consistent weather can do in this final stage of a melting season that has seen a huge amount of melting momentum being built up. The only question left is how close 2020 can still get to 2012.

Keep those animations coming, everyone. Especially of the ice edge retreat/annihilation between 135° and 60° East. What a stunning sight that is. I think animations will be jaw-dropping by next week.
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Re: The 2020 melting season
« Reply #5679 on: September 02, 2020, 01:02:40 AM »
That's really great BornFromTheVoid, many thanks.

Unfortunately I don't have time to do the animation this evening. But hopefully an image will suffice for now!

BFTV, I think that the graphic you created is great.  It is very informative to see the progression of the melting for each time period during July and August.   Thanks again for your great contributions to the Forum.
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Re: The 2020 melting season
« Reply #5680 on: September 02, 2020, 01:09:25 AM »
NSIDC is also seeing the collapse of the Beaufort Sea ice bagel. The Laptev Sea is even closer to the absolute record of 2014 - 1029.22 km2.

Its a bagel!!!  I thought it was a donut.   Or the tail of the Arctic sting ray.
« Last Edit: September 02, 2020, 01:16:23 AM by ArcTickTock »

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Re: The 2020 melting season
« Reply #5681 on: September 02, 2020, 01:13:02 AM »
Its clear as day that there is a major correlation between bathymetry and the ice edge.


It is much harder to melt ice over the super deep parts of the Arctic

Guess it is difficult to establish a proper thermohalocline in 50 meters or less?

As to the debate as to whether bathymetry matters with respect to sea ice melt, of course it does, every component of the complex Arctic system that possibly can have an effect does matter.  If it was a simple system with a handful of critical parameters it would all be figured out and there would be no need for a Sep. minimum poll.
« Last Edit: September 02, 2020, 01:29:41 AM by ArcTickTock »

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Re: The 2020 melting season
« Reply #5682 on: September 02, 2020, 01:45:52 AM »
I am wondering if the surging ice stream from the Vavilov Ice Cap has been reason for the delayed melting of the sea ice in the Severnaya Zemlya region. What impact would this have had on the salinity levels in that area.

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Re: The 2020 melting season
« Reply #5683 on: September 02, 2020, 02:15:03 AM »
Latest Five Day Forecast
Wind + Temp @ Surface
Large GiF!

Tell the fat lady not to start singing yet!
« Last Edit: September 02, 2020, 03:00:56 AM by Freegrass »
Now let's pray...

If the science don't fit our beliefs, we pray to God and cuddle up in our own delusional fantasy where everything makes sense again...

Shared Humanity

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Re: The 2020 melting season
« Reply #5684 on: September 02, 2020, 02:32:04 AM »
Latest Five Day Forecast
Wind + Temp @ Surface
Large GiF!

Tell the fat lady she can't start singing yet!

Weather from hell. Made to order for compacting the remaining fragmented ice up against the CAA while melting the edge. I'd expect SIE to continue to drop.

glennbuck

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Re: The 2020 melting season
« Reply #5685 on: September 02, 2020, 02:43:50 AM »
Severnaya Zemlya and Franz Josef Land, 90° east to 30° east, pushing towards the North Pole on the 30th August last clear view.
« Last Edit: September 02, 2020, 03:03:08 AM by glennbuck »

Freegrass

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Re: The 2020 melting season
« Reply #5686 on: September 02, 2020, 02:46:46 AM »
Latest Five Day Forecast
Wind + Temp @ Surface
Large GiF!

Tell the fat lady she can't start singing yet!

Weather from hell. Made to order for compacting the remaining fragmented ice up against the CAA while melting the edge. I'd expect SIE to continue to drop.
Let's wait and see tomorrow, because these forecasts can change on a dime. But it's not looking good right now. With this forecast, all the remaining ice would be impacted...
Now let's pray...

If the science don't fit our beliefs, we pray to God and cuddle up in our own delusional fantasy where everything makes sense again...

Sublime_Rime

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Re: The 2020 melting season
« Reply #5687 on: September 02, 2020, 03:50:11 AM »
Quote

It took me a while to get it into my stubborn brain, but it's all about the salt. Salinity is way more important than any other factor. I'm hope Uniquorn agrees with me on that. The end result of a melting season completely depends on the weather. Salinity dictates the ice edge, not bathymetry.


I think we might be simplifying things a bit here Freegrass? Nothing operates in isolation. Salinity is strongly influened by underlying bathymetry. Its also influenced by encroaching Atlantification and Pacification, as well as the melting of the ice itself.

Sure, salinity has a large influence on both freezing point and therefore heat moving through the water and being able to melt ice, but it is influenced by innumerable other factors (wind, ocean temperature gradients, bathymetry, ice cover, precipitation, insolation, etc etc). The end result of the melting season does not "completely depend on the weather." That is to deny the conditioning of the ice in innumerable ways by the previous melting and freezing seasons, direct and indirect effects of AGW, climate variability on the year to decade scale ... on and on. One must surely take a systems approach to understand all this, and even then simplification will be necessary. 
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JNap

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Re: The 2020 melting season
« Reply #5688 on: September 02, 2020, 05:33:21 AM »
JAXA September 1st reading:  3,894,998.  A loss of approximately 48k in extent.   Given the current High pressure, it seems like it will keep compacting the ice and reduce extent for the next 4 - 5 days  at least.

Historically, the average extent reduction from September 1st to the minimum is about 200k.  If I remember correctly, the maximum September extent reduction was approximately 450k back in 2010. 

I think that this year will have a greater than average extent reduction in September given the current weather conditions and the accumulation of heat content in the arctic from solar insolation during strong GAAC in July.  My guess that that we will see a 350k - 400k September extent reduction.  That would put the minimum at 3.55 - 3.6 million km2.

We will all find out together in the next few weeks whether this is a good prediction.
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Re: The 2020 melting season
« Reply #5689 on: September 02, 2020, 05:53:56 AM »
The ice on the ESS side of the CAB is an area that really needed to melt out to 82/83N for 2020 to have a real shot at trying to reach 3 million km2 or less.


That didn't happen.

But this area also didn't get almost any compacting winds and ice from the beaufort/chuckchi was sent this way
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Simon

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Re: The 2020 melting season
« Reply #5690 on: September 02, 2020, 07:31:00 AM »
Is it me or does the ice have the shape of a dog with a Beaufort tail?

ArcticMelt2

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Re: The 2020 melting season
« Reply #5691 on: September 02, 2020, 07:33:15 AM »
In the Laptev Sea, 2020 finally took a new absolute record.  :'(

1. 2020    379 km2
2. 2014    887 km2
3. 2018   9031 km2
4. 2013  11830 km2
5. 2011  14157 km2
6. 2012  21509 km2

EDIT>>> What data are you quoting? (It certainly isn't NSIDC 5 day trailing average)

I took data from here

ftp://sidads.colorado.edu/DATASETS/NOAA/G02186/masie_4km_allyears_extent_sqkm.csv

ftp://sidads.colorado.edu/DATASETS/NOAA/G02186/masie_4km_extent_sqkm.csv


3.6 according to the University of Bremen

https://www.meereisportal.de/en/

110k for the last day

binntho

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Re: The 2020 melting season
« Reply #5692 on: September 02, 2020, 08:51:19 AM »
Its clear as day that there is a major correlation between bathymetry and the ice edge.


It is much harder to melt ice over the super deep parts of the Arctic
Why should it be "much harder"? And what research have you or others done to establish a "major correlation"?

There is correlation, but there is also the co-incidence of the deepest waters being furthest north, and on the Atlantic front, sheltered by a string of islands. Both of these factors could be responsible for a stronger apparent correlation than the what is in fact happening.
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binntho

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Re: The 2020 melting season
« Reply #5693 on: September 02, 2020, 09:03:14 AM »
The ice retreats from the south, and by far the biggest factors are heat and insolation. Salinity and bathymetry are bumps on the way from maximum to minimum.

Salinity changes with ice cover, so correlation is not equal to causation. Currents fluctuate and are most likely also changing due to decrasing ice cover. Bathymetry is static, and doesn't really make any difference for either seasonal melt or long-term decline.
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gerontocrat

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Re: The 2020 melting season
« Reply #5694 on: September 02, 2020, 09:07:58 AM »
In the Laptev Sea, 2020 finally took a new absolute record.  :'(

1. 2020    379 km2
2. 2014    887 km2
3. 2018   9031 km2
4. 2013  11830 km2
5. 2011  14157 km2
6. 2012  21509 km2

EDIT>>> What data are you quoting? (It certainly isn't NSIDC 5 day trailing average)

I took data from here

ftp://sidads.colorado.edu/DATASETS/NOAA/G02186/masie_4km_allyears_extent_sqkm.csv

ftp://sidads.colorado.edu/DATASETS/NOAA/G02186/masie_4km_extent_sqkm.csv


3.6 according to the University of Bremen

https://www.meereisportal.de/en/

110k for the last day
High resolution sensors - one day measurement - all is explained.

But my take is that Laptev area and extent was at record daily lows for so many days this year.
Hence the sea is so hot, and other things being equal that should delay refreeze. Another sea in the Arctic making a big step towards open water status from late summer to late autumn?
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Re: The 2020 melting season
« Reply #5695 on: September 02, 2020, 09:27:50 AM »
The ice retreats from the south, and by far the biggest factors are heat and insolation.
This one is interesting - on Oceanic Heat Transport (OHT) & Atmospheric Heat Transport (AHT). Ocean heat transport more important.

https://journals.ametsoc.org/jcli/article/33/16/7197/348482/Impacts-of-Oceanic-and-Atmospheric-Heat-Transports

Impacts of Oceanic and Atmospheric Heat Transports on Sea Ice Extent
Quote
Our results suggest that the ice-edge latitude is always more sensitive to oceanic than atmospheric heat transport, but results depend on whether the ice cover exists perennially or seasonally.

In the perennial case, the ice-edge latitude is more sensitive to oceanic than atmospheric heat
transport by roughly a factor of 2 (found by varying the ocean–ice flux parameter Fbp), and by a further factor of 2 if the OHT perturbation is concentrated at the ice edge. This higher sensitivity to oceanic than atmospheric heating is consistent with previous studies .....

We showed that the ratio of perennial sensitivities is fairly robust to the background climate and is set to leading order by atmospheric feedback parameters. AHT is a less effective driver of the ice-edge latitude compared to OHT. This is because only a fraction of AHTC is transferred to the ice since some of it is lost via outgoing longwave radiation to space (or re-emission
from the surface). In contrast, any OHT converging under sea ice must be absorbed by it. Part of the absorbed ocean heat flux melts ice at the base, although a mechanism similar to the ice-thickness feedback plays a role in which the resulting thinner ice more effectively conducts
heat to the surface where it may be radiated away. When the ice cover is seasonal, the sensitivities of the (annual mean) ice edge to AHT and OHT are roughly the same, but both are larger than the perennial sensitivities. This is associated with uninhibited air–sea fluxes in ice-free
months making the two heat transports have similar roles to play in warming the high latitudes, and with increased solar absorption that further enhances warming.
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S.Pansa

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Re: The 2020 melting season
« Reply #5696 on: September 02, 2020, 09:39:04 AM »
Another, older, paper on the subject of bathymetry and SIE.
Nghiem et al, 2012. Seafloor control on sea ice. Deep Sea Research Part II: Topical Studies in Oceanography (Link)
Abstract
Quote
The seafloor has a profound role in Arctic Sea ice formation and seasonal evolution. Ocean bathymetry controls the distribution and mixing of warm and cold waters, which may originate from different sources, thereby dictating the pattern of sea ice on the ocean surface. Sea ice dynamics, forced by surface winds, are also guided by seafloor features in preferential directions. Here, satellite mapping of sea ice together with buoy measurements are used to reveal the bathymetric control on sea ice growth and dynamics. Bathymetric effects on sea ice formation are clearly observed in the conformity between sea ice patterns and bathymetric characteristics in the peripheral seas. Beyond local features, bathymetric control appears over extensive regions of the sea ice cover across the Arctic Ocean. The large-scale conformity between bathymetry and patterns of different synoptic sea ice classes, including seasonal and perennial sea ice, is identified. An implication of the bathymetric influence is that the maximum extent of the total sea ice cover is relatively stable, as observed by scatterometer data in the decade of the 2000s, while the minimum ice extent has decreased drastically. Because of the geologic control, the sea ice cover can expand only as far as it reaches the seashore, the continental shelf break, or other pronounced bathymetric features in the peripheral seas. Since the seafloor does not change significantly for decades or centuries, sea ice patterns can be recurrent around certain bathymetric features, which, once identified, may help improve short-term forecast, seasonal outlook, and decadal prediction of the sea ice cover. Moreover, the seafloor can indirectly influence the cloud cover by its control on sea ice distribution, which differentially modulates the latent heat flux through ice covered and open water areas.


The paper is mentioned on the Arctic Sea Ice news from November 2012. There, the NSIDC writes:
Quote
Research by our colleagues Jamie Morison at the University of Washington Seattle and NASA scientist Son Nghiem suggests that bathymetry (sea floor topography) plays an important role in Arctic sea ice formation and extent by controlling the distribution and mixing of warm and cold waters. At its seasonal minimum extent, the ice edge mainly corresponds to the deep-water/shallow-water boundary (approximately 500-meter depth), suggesting that the ocean floor exerts a dominant control on the ice edge position. However, in some cases, ice survives in the shallower continental shelf regions due to water circulation patterns. For example, the shelf area of the East Greenland Sea is almost always covered with sea ice because the southward-flowing cold Arctic surface water helps to limit melt.

In contrast, ice disappears in shallow areas like the Barents and Chukchi seas that are subject to warm ocean waters and river runoff. River runoff and ice melting have also contributed to changes in the amount and distribution of fresh water in the Arctic.

binntho

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Re: The 2020 melting season
« Reply #5697 on: September 02, 2020, 09:39:25 AM »
The ice retreats from the south, and by far the biggest factors are heat and insolation.
This one is interesting - on Oceanic Heat Transport (OHT) & Atmospheric Heat Transport (AHT). Ocean heat transport more important.
Exactly what I would expect, and I'm surprised that it is only a factor of 2.
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binntho

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Re: The 2020 melting season
« Reply #5698 on: September 02, 2020, 09:50:07 AM »
Another, older, paper on the subject of bathymetry and SIE.
Nghiem et al, 2012. Seafloor control on sea ice. Deep Sea Research Part II: Topical Studies in Oceanography (Link)
Abstract
Thanks Pansa. But reading these two quotes makes me more confused than not. It seems that when Nghiem et al say that bathymetry has a "profound" effect, they seem to be at least partially talking about the shoreline - i.e. that ice maximum doesn't change much from year to year because it is constrained by the shoreline. And the shoreline is apparently a part of bathymetry. Which is indeed a major effect! Other than that it is mostly general observaions that I think we all could agree with.

In the second quote from NSIDC i read the following with wonder and consternation: "At its seasonal minimum extent, the ice edge mainly corresponds to the deep-water/shallow-water boundary (approximately 500-meter depth)" ... well perhaps in times past but not in recent memory.
because a thing is eloquently expressed it should not be taken to be as necessarily true
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BornFromTheVoid

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Re: The 2020 melting season
« Reply #5699 on: September 02, 2020, 10:31:50 AM »
Today's daily images and animation. The loss on the Atlantic side is really beginning to stand out now.
As usual, there's a larger version of the animation on the twitter page.
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel