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Glenn_Tamblyn

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Re: The 2020 melting season
« Reply #5700 on: September 02, 2020, 10:54:12 AM »
Hi all.

I have been lurking recently (I have posted a bit in the past), watching an astonishing melt season.The astonishing opening up and particularly melt ponding north of Greenland leads me to a speculation I don't think I have seen discussed here.

What impact could melt ponding have on ice strength in future seasons?

If a melt pond doesn't drain it will eventually refreeze, possible with a different crystal structure.

However, if a melt pond drains, could that trigger other issues. A while back scientists identified a mechanism they think is involved in the collapse of large ice shelves. Obviously they are fresh water ice and a couple of orders of magnitude thicker but might the same mechanism apply to sea ice?

- Melt pond forms, down to some depth.
- Melt pond drains away.
- The ice beneath the melt pond now needs to rise to rebalance buoyancy.
- But the ice surrounding the drained pond doesn't need to adjust.
- Thus leading to stresses in the ice around the edges of the empty pond as the empty pond tries to rise, and potentially cracking.
- Repeated occurrences of this is believed to lead to a cascading failure and collapse of ice shelves.

Could the same mechanism be at work in sea ice, leading to progressive weakening that may show up in later seasons? Could what we have seen north of Greenland have primed the region for even bigger collapses next year?

be cause

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Re: The 2020 melting season
« Reply #5701 on: September 02, 2020, 11:18:07 AM »
hi Glenn .. not if that ice has disappeared via Fram (or otherwise) long before next melt season .. b.c.
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 + 2 = 2021 + 1 =  ' if only we could have seen it coming ' ...

nanning

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Re: The 2020 melting season
« Reply #5702 on: September 02, 2020, 12:08:34 PM »
Thanks again for your effort BornFromTheVoid, imo that's a great visual in your post #5673.
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Jim Hunt

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Re: The 2020 melting season
« Reply #5703 on: September 02, 2020, 12:29:16 PM »
I took data from here

In which case I suggest that you read my 2016 interview with Walt Meier regarding the deficiencies of MASIE when it comes to inter-year comparisons:

https://GreatWhiteCon.info/2016/02/dmi-masie-and-the-sea-ice-index-an-interview-with-walt-meier/
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

S.Pansa

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Re: The 2020 melting season
« Reply #5704 on: September 02, 2020, 12:30:16 PM »
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. ...

 :) I was afraid I am the only one who got confused.
In the meantime I found the full paper but I can't say that it eased my confusion - most probably I am lost in translation though.

From a quick glance it looks to me it is partly old news, see for instance Fig 4.
But I definitely shouldn't judge a research paper after just skimming through. Sure you guys can get more out of it.

Caption Fig 4
Quote
Histogram of sea ice distribution and best-conformed isobaths for (a-b) 20 September 2009,  (c-d)  20  October  2009,  and  (e-f)  20  November  2009.    The  left  panels  are  for  cumulative percentage  of  sea  ice  versus water  depth.    The  right  panels  show  the  best conformedisobaths (yellow contour at depth indicated in yellow label in each panel) to the ice edges (red contour) in Copyright 2011. All rights reserved.Page 26panels (b) and (d), and to the seasonal ice boundary in panel (f), where open water, seasonal ice, mixed  ice,  and  perennial  ice  are  indicated  with  shades  of  blue  from  the  darkest  to  the  lightest, respectively.    White  areas  are  not  considered  in  the  analysis  to  determine  the  best-conformed isobaths.

Freegrass

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Re: The 2020 melting season
« Reply #5705 on: September 02, 2020, 02:09:56 PM »
I think we might be simplifying things a bit here Freegrass?
Me? Simplifying things? I wouldn't dare...  ::)
Just happy it got a good debate going and I was able to learn a few things... ;)
Now let's pray...

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Freegrass

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Re: The 2020 melting season
« Reply #5706 on: September 02, 2020, 02:26:02 PM »
Latest Five Day Forecast
Wind @ Surface
Large GiF!

Watch the wind coming out of Nares!
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...

Lord M Vader

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Re: The 2020 melting season
« Reply #5707 on: September 02, 2020, 02:32:00 PM »
Wow, almost a double CB loss at NSIDC SIE. But it is the 1th in the month. But still.. And we are now on the brink to go below 4Mn km2....

Alison

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Re: The 2020 melting season
« Reply #5708 on: September 02, 2020, 03:24:20 PM »
...for the second time ever

Shared Humanity

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Re: The 2020 melting season
« Reply #5709 on: September 02, 2020, 03:36:00 PM »
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.

BFTV - I think you have developed a near perfect animation for watching the progression of melt.

I am still very concerned about the drop in concentration (yellow area) that is occurring along the Atlantic side as the ice edge moves north. It suggests that melt is playing a bigger role than compaction.

And Freegrass's animation suggests the wind pattern that is driving this will not let up for at least 5 days.
« Last Edit: September 02, 2020, 03:42:57 PM by Shared Humanity »

BornFromTheVoid

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Re: The 2020 melting season
« Reply #5710 on: September 02, 2020, 03:40:51 PM »
Cheers, SH!

With today's near double century drop, the thought of reaching the 2012 minimum begins to seem a little less far fetched.
If we follow the melt of 2010, we'll end up just 125k off 2012...
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

Paul

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Re: The 2020 melting season
« Reply #5711 on: September 02, 2020, 04:34:42 PM »
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.

BFTV - I think you have developed a near perfect animation for watching the progression of melt.

I am still very concerned about the drop in concentration (yellow area) that is occurring along the Atlantic side as the ice edge moves north. It suggests that melt is playing a bigger role than compaction.

And Freegrass's animation suggests the wind pattern that is driving this will not let up for at least 5 days.

It does look like though the high is breaking down and is going to be replaced by increasing low pressure, could be quite strong also. How it sets up will determine how much cold air comes into play and where it spreads out also yet at the same time other areas could still be well above average if the winds still come in off the open water.

I do think the Atlantic edge will eventually stop retreating soon though as that small low heads toward the pole so whilst the ice edge in the Laptev still gets winds off the sea, the winds should be coming from the ice on the bottom side of the low, it may push the ice southward again.

I'll be interested too see volume numbers though, may avoid record lows(by little margin really) if the ice in the Beaufort survives.

mdoliner

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Re: The 2020 melting season
« Reply #5712 on: September 02, 2020, 04:51:42 PM »
Melt ponds cannot drain. nine tenths of the floe is below sea level.

Freegrass

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Re: The 2020 melting season
« Reply #5713 on: September 02, 2020, 04:52:10 PM »
Last and Next 48 Hours
Wind @ Surface

I have no idea why there's still ice left on the Greenland coast this late in the season and after 2 days of battering like this. How thick is that ice there that's still clinging to the Greenland coast? And will it vanish in the next two days of onslaught?
« Last Edit: September 02, 2020, 05:06:38 PM by Freegrass »
Now let's pray...

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Shared Humanity

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Re: The 2020 melting season
« Reply #5714 on: September 02, 2020, 05:05:00 PM »
Melt ponds cannot drain. nine tenths of the floe is below sea level.

??? Once melt water has punched through the ice floe, it will seek its own level which would be sea level.

Shared Humanity

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Re: The 2020 melting season
« Reply #5715 on: September 02, 2020, 05:06:20 PM »
Last and Next 48 Hours
Wind @ Surface

I have no idea why there's still ice left on the Greenland coast after 2 days of battering like this. How thick is that ice there that's still clinging to the Greenland coast? And will it vanish in the next two days of onslaught?

I can't imagine how it would all melt.

Freegrass

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Re: The 2020 melting season
« Reply #5716 on: September 02, 2020, 05:12:13 PM »
Last and Next 48 Hours
Wind @ Surface

I have no idea why there's still ice left on the Greenland coast after 2 days of battering like this. How thick is that ice there that's still clinging to the Greenland coast? And will it vanish in the next two days of onslaught?

I can't imagine how it would all melt.
But it's so late in the season, so why is there still ice left this far south? In earlier years it was all gone by now. And now we still have thick persistent ice there?

This must be very thick ice that got transported out of Fram during winter, or it wasn't as cold there as other years?
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...

nanning

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Re: The 2020 melting season
« Reply #5717 on: September 02, 2020, 05:28:56 PM »
Quote from: Freegrass
or it wasn't as cold there as other years?

Always the fat cats who go on vacation when they feel the heat.
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Killian

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Re: The 2020 melting season
« Reply #5718 on: September 02, 2020, 05:39:33 PM »
Cheers, SH!

With today's near double century drop, the thought of reaching the 2012 minimum begins to seem a little less far fetched.
If we follow the melt of 2010, we'll end up just 125k off 2012...

Interesting factoid: Extent decrease from Aug 13 to Sept 1 in '12 and '00? Exactly the same according to JAXA.

 :o

UCMiami

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Re: The 2020 melting season
« Reply #5719 on: September 02, 2020, 06:05:14 PM »
Last and Next 48 Hours
Wind @ Surface

I have no idea why there's still ice left on the Greenland coast after 2 days of battering like this. How thick is that ice there that's still clinging to the Greenland coast? And will it vanish in the next two days of onslaught?


I can't imagine how it would all melt.
But it's so late in the season, so why is there still ice left this far south? In earlier years it was all gone by now. And now we still have thick persistent ice there?

This must be very thick ice that got transported out of Fram during winter, or it wasn't as cold there as other years?
There are a number of islands behind which the ice can hide, and to which it remains anchored late into the summer, and there is a lot of ice that remains at glacier heads in the various fjords but eventually loosens and makes it to the coast. I am sure there is some stacking up of flows against the east Greenland coast in winter, and some of the ice is likely glacial in origin. In addition, Greenland provides both a refrigerator on one flank but also tons of zero degree fresh glacial run off that provides a buffer to any warm saline ocean infringement.

This is a pretty standard condition for NE Greenland at this stage of summer, especially at the end of a very strong Fram export winter and spring. And yes, a lot of that export was thick ice but that ice probably did not replace the native coastal ice that remains, just provide additional buffer against any Atlantic water.

And while strong winds are detrimental, these storms so far have brought cold winds and at points the precipitation has been frozen. And quite a bit of the ice has remained in the lee of the Greenland coast.
« Last Edit: September 02, 2020, 06:12:58 PM by UCMiami »

gerontocrat

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Re: The 2020 melting season
« Reply #5720 on: September 02, 2020, 06:08:13 PM »
Last and Next 48 Hours
Wind @ Surface

I have no idea why there's still ice left on the Greenland coast after 2 days of battering like this. How thick is that ice there that's still clinging to the Greenland coast? And will it vanish in the next two days of onslaught?
I can't imagine how it would all melt.
But it's so late in the season, so why is there still ice left this far south? In earlier years it was all gone by now. And now we still have thick persistent ice there?

This must be very thick ice that got transported out of Fram during winter, or it wasn't as cold there as other years?
Perhaps, as the Central Arctic got more fragile, i.e. less solid. the Fram exported more and more ice down East Greenland courtesy of the East grrenalnd Current. There certainly was a large export of ice into the Greenland Sea earlier in the year.

So that extra sea ice is maybe, not a sign of resilience / rebound / recovery, but rather of of decay.
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ArcticMelt2

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Re: The 2020 melting season
« Reply #5721 on: September 02, 2020, 06:34:13 PM »

BornFromTheVoid

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Re: The 2020 melting season
« Reply #5722 on: September 02, 2020, 06:53:23 PM »
Though ye might like this.

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

dnem

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Re: The 2020 melting season
« Reply #5723 on: September 02, 2020, 06:59:40 PM »
BFTV, your image processing is just phenomenal!

Freegrass

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Re: The 2020 melting season
« Reply #5724 on: September 02, 2020, 07:01:45 PM »
All good reasons UCMiami and Gerontocrat. Thank you! :) I suppose it must be a little bit of all of the above. But I've been wondering all season long about another reason. Correct me if I'm wrong, but when I went through the extent images from previous years a while back, I noticed that the last 5 years or so that there was a lot more ice left in the CAA and on the eastern Greenland coast.

I also remember that this spring the temperatures in Siberia were above normal, while in North America they were below normal. So I've been wondering if this is all happening because Greenland start functioning more as the pole? Will it become a trend that Greenland and North America will have a delayed spring (due to a shifting polar cell?), and does this cause the ice in the CAA and the East Greenland coast to last longer?

I guess the question is if arctic amplification will be felt harder in Siberia than in America...

Quote
In addition, Greenland provides both a refrigerator on one flank but also tons of zero degree fresh glacial run off that provides a buffer to any warm saline ocean infringement.
I told you it was all about the salt!  ;D (just joking)
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...

ArcticMelt2

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Re: The 2020 melting season
« Reply #5725 on: September 02, 2020, 07:07:28 PM »
Though ye might like this.

This is outdated data.


ArcticMelt2

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Re: The 2020 melting season
« Reply #5726 on: September 02, 2020, 07:12:50 PM »
Yesterday's image:


gerontocrat

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Re: The 2020 melting season
« Reply #5727 on: September 02, 2020, 07:13:38 PM »
The attached image makes its clear how remaining extent loss to minimum in 2010 was twice the 10 year average.

Suggests 2020 might not match it.
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gerontocrat

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Re: The 2020 melting season
« Reply #5728 on: September 02, 2020, 07:17:39 PM »
So I've been wondering if this is all happening because Greenland start functioning more as the pole? Will it become a trend that Greenland and North America will have a delayed spring (due to a shifting polar cell?), and does this cause the ice in the CAA and the East Greenland coast to last longer?
Shades of the tentacles of a certain reglaciation speculation tentatively sniffing at the melting season thread?
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D-Penguin

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Re: The 2020 melting season
« Reply #5729 on: September 02, 2020, 07:23:05 PM »
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.

A very reasonable prediction.

However, if the date of the minimum is extended by 10 days say, then who knows?
Remember...it's all about the Jet Stream you dummy...just a personal reminder!

Freegrass

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Re: The 2020 melting season
« Reply #5730 on: September 02, 2020, 08:10:38 PM »
So I've been wondering if this is all happening because Greenland start functioning more as the pole? Will it become a trend that Greenland and North America will have a delayed spring (due to a shifting polar cell?), and does this cause the ice in the CAA and the East Greenland coast to last longer?
Shades of the tentacles of a certain reglaciation speculation tentatively sniffing at the melting season thread?
No, not at all. I just remembered conversations here about a shifting polar cell and I am wondering if we are seeing the first signs of that. I have no idea what the impact of that will be, but I'm quite sure that reglaciation will not be a part of that. I can imagine that an icefree arctic ocean will heat up Cannada quite dramatically?
Now let's pray...

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Burnrate

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Re: The 2020 melting season
« Reply #5731 on: September 02, 2020, 08:11:54 PM »
So I've been wondering if this is all happening because Greenland start functioning more as the pole? Will it become a trend that Greenland and North America will have a delayed spring (due to a shifting polar cell?), and does this cause the ice in the CAA and the East Greenland coast to last longer?
Shades of the tentacles of a certain reglaciation speculation tentatively sniffing at the melting season thread?

Greenland having more ice than the arctic will definitely have some kind of effect.  A delayed spring, among other things, doesn't suggest "re-glaciation" at all.  I just wanted to say this because I wouldn't want to see discussion of the effects of a shifting polar cell always equated with people claiming a new ice age is coming.

bbr2315

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Re: The 2020 melting season
« Reply #5732 on: September 02, 2020, 08:26:01 PM »
The remaining ice on the Lincoln Sea "front" is in for an, erm, imminently rough go of things if the 12z EURO is correct.... the LP event at D5 is now down to 980mb and the LP around Iceland is now closer to FRAM.


Freegrass

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Re: The 2020 melting season
« Reply #5733 on: September 02, 2020, 08:31:56 PM »
Latest Five Day Forecast
Wind @ Surface + Total Precipitable Water
Large GiF!

Ay Caramba...  ???
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oren

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Re: The 2020 melting season
« Reply #5734 on: September 02, 2020, 08:33:55 PM »
So I've been wondering if this is all happening because Greenland start functioning more as the pole? Will it become a trend that Greenland and North America will have a delayed spring (due to a shifting polar cell?), and does this cause the ice in the CAA and the East Greenland coast to last longer?
Shades of the tentacles of a certain reglaciation speculation tentatively sniffing at the melting season thread?

Greenland having more ice than the arctic will definitely have some kind of effect.  A delayed spring, among other things, doesn't suggest "re-glaciation" at all.  I just wanted to say this because I wouldn't want to see discussion of the effects of a shifting polar cell always equated with people claiming a new ice age is coming.

The Arctic Basin is filled with ice to the brim until the end of April every year. Even a BOE will not change that, therefore Greenland will not have more ice than the Arctic in time to affect a delayed spring in NA even if it made sense for such a mechanism, and there is no reason to speculate on this too much. If anything, an ice-free Arctic will have major impacts on NA in the fall and early winter. In any case such in-depth discussions are better off being held in another thread.


wili

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Re: The 2020 melting season
« Reply #5735 on: September 02, 2020, 08:47:17 PM »
wrt to fg's question: Aren't katabatic winds fairly common coming off of GIS? Wouldn't those be cold enough to (re)freeze coastal waters?

Also, isn't the water just off Greenland quite 'fresh'/less salty because of all the melt from GIS, so it would freeze more easily?
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ms

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Re: The 2020 melting season
« Reply #5736 on: September 02, 2020, 09:00:07 PM »
Just guessing abort fg's question:
I have been wondering about the ice off Greenland east coast too.
Normaly it would pass south and melt in warmer water.
But we have had an unusual amount of southernly wind, pressing the ice northward and maybe getting stuck along the coast in colder water than normal.
Could that be part of the explanation?

harpy

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Re: The 2020 melting season
« Reply #5737 on: September 02, 2020, 09:11:37 PM »
The truth is that no one really knows for sure what will happen when the BOE takes place.

To name just a sources, there's certain individuals I would trust more heavily on this subject than others.

Two who come immediately to mind are Paul Beckwith, and Peter Whadams.
« Last Edit: September 02, 2020, 09:18:18 PM by harpy »

bbr2315

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Re: The 2020 melting season
« Reply #5738 on: September 02, 2020, 09:14:03 PM »



It is a Day 10 forecast but I think it is unusually reliable because it is prognosticated on several happenings in the short-medium term.

1) There is a barrage of typhoons / hurricanes inbound for the Arctic, the wave train from both PAC and ATL is fairly consistent and on the PAC side it is amping up very significantly imminently, with a major event possibly impacting Japan shortly. This will aid a massive +500MB heat flux that will head poleward (as will the other events).

2) Snow coverage is forecast to begin extending its reach in earnest according to 12z modeling. While Eurasian coverage will be lackluster outside the Himalayas and Siberian mountains (for now), North American extent is forecast to begin descending across most Canadian mountain ranges (Rockies and Quebec) by D10 of today's 12z EURO. MORE significantly, the EURO is showing a major snowfall event taking place by D5 in the Rockies, covering a very major area with a very deep amount of snow.

Such an anomalous event occurring so low in latitude is likely to evacuate a major portion of oceanic heat poleward in its occurrence and aftermath (both Pacific and Gulf of Mexico). I think this is why the 12z EURO's depiction of the D8-10 range may be more reliable than normal, and the aforementioned reasons combined with the extant state of the Arctic means this September may be much more active on the melt front than is typical.

« Last Edit: September 03, 2020, 12:37:59 AM by bbr2315 »

slow wing

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Re: The 2020 melting season
« Reply #5739 on: September 02, 2020, 11:46:40 PM »
September 1 is one of the year-to-year comparison dates for the U Bremen ASI (from AMSR2) false colour concentration maps, see attached figure. Shown are this year, in the lower right corner, and seven of the previous low years. The other 8 recent years can be seen by clicking the link.

This year, the ice is unusually compact for the date.


VeganPeaceForAll

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Re: The 2020 melting season
« Reply #5741 on: September 03, 2020, 12:18:24 AM »
September 1 is one of the year-to-year comparison dates for the U Bremen ASI (from AMSR2) false colour concentration maps, see attached figure. Shown are this year, in the lower right corner, and seven of the previous low years. The other 8 recent years can be seen by clicking the link.

This year, the ice is unusually compact for the date.

When you say it is compact, have you taken all the clouds into account? Lots of cloud cover would give a false impression that the ice is compact, as it would show up with a dark purple colour.

gandul

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Re: The 2020 melting season
« Reply #5742 on: September 03, 2020, 01:05:04 AM »
Latest Five Day Forecast
Wind @ Surface + Total Precipitable Water
Large GiF!

Ay Caramba...  ???
Caramba indeed, the beating over Laptev bite is gonna be antológico.
Perhaps extent losses will be softened with first signs of refreeze at the ice edge, because temps at the ESS tip are really sinking now.
Then the cold centered low from day 5 should end the extent losses for now. Right?

gandul

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Re: The 2020 melting season
« Reply #5743 on: September 03, 2020, 01:15:41 AM »
September 1 is one of the year-to-year comparison dates for the U Bremen ASI (from AMSR2) false colour concentration maps, see attached figure. Shown are this year, in the lower right corner, and seven of the previous low years. The other 8 recent years can be seen by clicking the link.

This year, the ice is unusually compact for the date.
Yep, except for the Beaufort sea ice.
And the ice should thank the compacting GAAC and August 2nd half wind pattern from this. A nice packed bunch of broken, tilted, stacked non-distancing floes, inundated by relatively cold ocean water due to melt pond drainage, a gruyere that anyway is refreezing to continue the journey. A first/second year fractional ice.

Shared Humanity

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Re: The 2020 melting season
« Reply #5744 on: September 03, 2020, 02:03:50 AM »
Latest Five Day Forecast
Wind @ Surface + Total Precipitable Water
Large GiF!

Ay Caramba...  ???
Caramba indeed, the beating over Laptev bite is gonna be antológico.
Perhaps extent losses will be softened with first signs of refreeze at the ice edge, because temps at the ESS tip are really sinking now.
Then the cold centered low from day 5 should end the extent losses for now. Right?

Bottom melt is in the driver seat this time of year. Until SST's drop below 2C, we won't see any substantial freeze.

Freegrass

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Re: The 2020 melting season
« Reply #5745 on: September 03, 2020, 02:12:25 AM »
Latest Five Day Forecast
Wind + Temp @ Surface
Large GiF!

Can we still break the record if this really happens?
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...

oren

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Re: The 2020 melting season
« Reply #5746 on: September 03, 2020, 04:28:49 AM »
Comparisons with previous years shows the uniqueness the Atlantic side retreat, and also the improbability of Beaufort survival coupled with a low ice year. The only year that comes close along the Barents CAB front is 2013, which had lots of ice elsewhere.

oren

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Re: The 2020 melting season
« Reply #5747 on: September 03, 2020, 04:37:26 AM »
Osi Saf still reporting lots of ice movement, not surprising given the Nullschool animations we've been looking at. Movement has subsided along the Laptev front but increased at the Barents front. In addition, the Beaufort arm has finally responded to the persistent air flow and started moving as well. With wind not forecast to let up but actually intensify, bottom melt quite significant (as also reported on the Mosaic thread) and the CAB ice disturbingly thin, a cold spell and initial refreeze had better come soon - or else.

Click to enlarge.
« Last Edit: September 03, 2020, 04:43:02 AM by oren »

Aluminium

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Re: The 2020 melting season
« Reply #5748 on: September 03, 2020, 05:56:29 AM »
August 29 - September 2.

2019.

binntho

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Re: The 2020 melting season
« Reply #5749 on: September 03, 2020, 06:13:29 AM »
wrt to fg's question: Aren't katabatic winds fairly common coming off of GIS? Wouldn't those be cold enough to (re)freeze coastal waters?

Also, isn't the water just off Greenland quite 'fresh'/less salty because of all the melt from GIS, so it would freeze more easily?
This misunderstanding of anabatic (upflowing) and katabatic (downflowing) winds seems to be quite common. As air rises over a mountain range (or ice sheet) it cools due to a fall in pressure. As it descends on the other side, it warms up again due to increased pressure, so the two effects cancel each other out. This is also called the adiabatic process and is what enables  fridges and airconditioners to work. 

What seems to happen quite often in Greenland is a foehn (or chinook) wind, which is caused when the rising air is humid, causing precipitation and release of latent heat, with the result that once the air reaches ground level again it is actually warmer than before. This can quite often be seen along the north coast of Greenland in Nullschool.

When air blows over a large stretch of ice it will lose heat to the ice, so in the case of Greenland ice sheet, dry air that does not experience the foehn effect will presumably be somewhat colder on theleewards side.

As for meltwater runoff from Greenland, the major part of that happens during summer. Almost all the major sources of runoff face the East Greenland Current or it's extension, the West Greenland Current, and  any runoff is carried away fairly fast and effectively disappears in these two currents and is nowhere near the Arctic by the time refreeze kicks in.
because a thing is eloquently expressed it should not be taken to be as necessarily true
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