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Freegrass

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Re: The 2020 melting season
« Reply #2250 on: July 05, 2020, 09:49:35 PM »
Latest Five Day Forecast
Wind @ Surface
Wind @ Surface + Total Cloud Water
Wind @ 250hPa

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Lord M Vader

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Re: The 2020 melting season
« Reply #2251 on: July 05, 2020, 10:00:58 PM »
ArcticMelt: a possible explanation might be an earlier melt onset in 2012 and perhaps less snow cover onto the ice.

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Re: The 2020 melting season
« Reply #2252 on: July 05, 2020, 10:50:04 PM »
Arctic ice drift map
A closer look at Beaufort drift from whoi itp buoys, mar31-jul4. Osisaf may already be using this data.
Will try to add the SIMB data next time

Also an update of ascat, this time overlaid with uni-hamburg amsr2-uhh at 75% transparent, mar21-jul4. Amsr2 100% concentration ice has been set to transparent to allow the ascat features to show through. 2.2MB
ascat contrast altered later in the animation in an attempt to highlight leads
« Last Edit: July 05, 2020, 11:01:50 PM by uniquorn »

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Re: The 2020 melting season
« Reply #2253 on: July 06, 2020, 01:25:42 AM »
I'm here. I learned from A-Team that, because sea ice is a deformable medium, the best thing to do is to look at markers of where it is moving.

It is nice to see you FOW!

I think I was not very clear in the point I was trying to make last night which lead to some confusion. There is no real dispute that as a general proposition high pressure leads to compaction and low pressure leads to dispersion. 

I was simply questioning one arrow on grixm’s map that had ice along the Atlantic moving north, and against the normal direction of Fram export.

The current setup as shown below in the 3 day average GFS looks to me like a good one for export to the Atlantic. At least in the short term if this forecast holds. I know the ice does not move in the exact direction the wind blows it. Under these conditions, I would expect the ice to move away from the high pressure system and towards the low pressure system (south) causing both Fram export and export between FJL and Svalbard. Maybe my understanding is wrong and it moves the opposite direction.

It will be interesting to see what happens.

Oren, I apologize for asking if anyone has a link to a scientific paper on this subject. That does not seem off topic to me. If we want a better understanding of the melting season, having a better understanding of the science will be helpful. 
« Last Edit: July 06, 2020, 02:20:39 AM by Rod »

Wildcatter

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Re: The 2020 melting season
« Reply #2254 on: July 06, 2020, 05:36:49 AM »
Yeah, this is going to be rough. Laptev and Kara and the Severnaya connection, Atlantic in general going to get pummeled. All with the ESS going down and the HPS.

Ouch. Probably the biggest volume drop ever coming from July 1 - July 15. Be interesting to see how it effects the CAB.

Going to be a lot of food for late-season cyclones this year.

oren

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Re: The 2020 melting season
« Reply #2255 on: July 06, 2020, 06:04:33 AM »
We often read about extent and area drops. A lot of times this involves ice transport, compaction, surface wetness, satellite artifacts and what have you. But sometimes ice just melts out and disappears, the 3D process finally manifesting in 2D.
Click to animate this recent 3-day GIF of the western Chukchi, with Wrangel Island at the bottom right corner. The ice streamers are a strong indication of continuing melt, about half of this whole patch should disappear in a few more days.

wdmn

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Re: The 2020 melting season
« Reply #2256 on: July 06, 2020, 06:13:10 AM »
I can't claim much skill at assessing these images, but it may turn out that the Beaufort will offer less protection for the CAB than some have suggested it would this year. Contrast turned up (thanks for the tip Pagophilus).

ArcTickTock

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Re: The 2020 melting season
« Reply #2257 on: July 06, 2020, 08:06:57 AM »
Arctic ice drift map
A closer look at Beaufort drift from whoi itp buoys, mar31-jul4. Osisaf may already be using this data.
Will try to add the SIMB data next time

Also an update of ascat, this time overlaid with uni-hamburg amsr2-uhh at 75% transparent, mar21-jul4. Amsr2 100% concentration ice has been set to transparent to allow the ascat features to show through. 2.2MB
ascat contrast altered later in the animation in an attempt to highlight leads

Thanks for this uniquorn, have to say the motion of #103 has me rethinking my notions of Beaufort  Sea ice motion, is a bee line dash along the coast like that common?

On another topic, I am struck this year by the apparent near total scouring of remnant coastal ice and drifting floes in the Southern Kara and Laptev.  I seem to recall these areas usually leaving lingering coastal remnants behind after melt out until later in the melt season.  Even factoring in the Laptev disaster does this seem unusual to anyone else?

Yes, it is my first post, will try not to be too ignorant!

Freegrass

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Re: The 2020 melting season
« Reply #2258 on: July 06, 2020, 08:15:06 AM »
Something has been brewing for a while now on the long term forecast, and it looks like the high will have to make place for a new low. I think it was Binntho who told me that this is basically the worst case scenario for the ice. Low, high, and low again. And if it's going to be this low, we're heading for disaster...

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oren

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Re: The 2020 melting season
« Reply #2259 on: July 06, 2020, 08:18:27 AM »
Welcome ArcTickTock. Yes I have also been bothered by the total cleanup in Kara/Laptev. I think it's not unprecedented but not common either, usually some thicker floes hang around for a while.

blumenkraft

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Re: The 2020 melting season
« Reply #2260 on: July 06, 2020, 08:32:02 AM »
Oren, I apologize for asking if anyone has a link to a scientific paper on this subject. That does not seem off topic to me. If we want a better understanding of the melting season, having a better understanding of the science will be helpful.

There is no apology needed. Asking for papers is indeed not off-topic, Rod. :)

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Re: The 2020 melting season
« Reply #2261 on: July 06, 2020, 08:35:33 AM »
Welcome to the forum, ArcTickTock.  :)

bluice

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Re: The 2020 melting season
« Reply #2262 on: July 06, 2020, 08:49:20 AM »
There seems to be a "wedge" of low concentration ice on the Siberian side from approximately 30E to 130E, it's northernmost corner reaching towards the Pole. It may be an artifact further north but Worldview confirms this closer to the melting edge in the south.

South from the ice are the open waters of the Kara and the Laptev.

The consensus is we are getting a dome of HP at the Pole. This will, among other things, cause easterly winds and concentration towards north. Weather forecast shows northeasterly winds along the Fram Strait meaning some export is also expected.

Should we expect a decimation of ice on this sector? Am I missing something or just a mistaken amateur newbie?

bbr2315

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Re: The 2020 melting season
« Reply #2263 on: July 06, 2020, 09:06:12 AM »
There seems to be a "wedge" of low concentration ice on the Siberian side from approximately 30E to 130E, it's northernmost corner reaching towards the Pole. It may be an artifact further north but Worldview confirms this closer to the melting edge in the south.

South from the ice are the open waters of the Kara and the Laptev.

The consensus is we are getting a dome of HP at the Pole. This will, among other things, cause easterly winds and concentration towards north. Weather forecast shows northeasterly winds along the Fram Strait meaning some export is also expected.

Should we expect a decimation of ice on this sector? Am I missing something or just a mistaken amateur newbie?
IMO, yes.

00z EURO is game over btw. It's cataclysmically terrible for the sea ice and that is not an understatement. It is really beginning to look like this may be the year to beat / shatter (?) 2012...

And unlike every other severe melt year we still have a decent amount of ice left in Hudson Bay to contribute to the continued cliff....!

The sector bolded in quoted post is going to be severely impacted through D10... the 00z EURO is beyond.






jdallen

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Re: The 2020 melting season
« Reply #2264 on: July 06, 2020, 09:18:18 AM »
We often read about extent and area drops. A lot of times this involves ice transport, compaction, surface wetness, satellite artifacts and what have you. But sometimes ice just melts out and disappears, the 3D process finally manifesting in 2D.
Click to animate this recent 3-day GIF of the western Chukchi, with Wrangel Island at the bottom right corner. The ice streamers are a strong indication of continuing melt, about half of this whole patch should disappear in a few more days.
Based anecdotally on looking at similar ice in past years, the top part of the image has about 5-7 days, the bottom/right part has 10-14 days.

Going back through the years looking at over-all ice quality, 2020 has a lot in common with 2012, except 2020 has more melt ponds.

2013 & 14 actually were far more broken up and dispersed, but didn't have the albedo drop, and were protected by cloudiness.  Those years, 2020's weather would have had a good chance of giving us a BOE.

Given continued high insolation, there are large swaths of the Chukchi and near-peripheral CAB that are about 3 weeks from mostly melting out, based on appearances and similar ice states in the past.

Also to emphasize, one thing that generally appears to be setting 2020 apart from previous years, even 2012, is the almost universal coverage of ice by melt ponds.  As other posters have mentioned, with full unimpeded insolation, that can lead to as much as 10cm/day of top melt. 

We desperately need cool cloudy conditions.
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Freegrass

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Re: The 2020 melting season
« Reply #2265 on: July 06, 2020, 10:55:18 AM »
So what is that, really?
I think the ice got "stretched out" there last week. That created a lot of open water between the flows.
That "stretch mark" as I called it back then is now showing up on the Slater model.

If it ends up like this...  :'(
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Freegrass

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Re: The 2020 melting season
« Reply #2266 on: July 06, 2020, 11:04:20 AM »
Five day forecast Wind @ Surface not looking good for the Barents sea ice.
This was the forecast I made on 420, and the reason for what Slater is showing us now IMHO. These storms did a lot of damage to the CAB at the end of April.
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jens

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Re: The 2020 melting season
« Reply #2267 on: July 06, 2020, 11:09:49 AM »
What do you think, what is the chance that melting could reach North Pole this year from the Russian side?

Freegrass

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Re: The 2020 melting season
« Reply #2268 on: July 06, 2020, 11:33:43 AM »
If a big low - like it is predicted on the long term - settles itself over the pole, then all that weakened ice will get dispersed while the bottom gets eaten at an accelerated pace. So it's looking very good for my prediction below 3 million m2, but it's looking very bad for the ice if we get a big storm right now. There's so much energy (heat and moisture) in the arctic, that a big storm is almost inevitable...

I'm sure Friv is starting to get excited by now. Right Friv? I'm dying to hear what you've got to say about the forecast.
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Pagophilus

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Re: The 2020 melting season
« Reply #2269 on: July 06, 2020, 12:28:59 PM »
Welcome ArcTickTock!
 
As Oren says, the near-total melting of coastal sections of the Laptev and Southern Kara can happen but not often (I would trust his experience faaaar more than mine).  IMO, the extreme and record heat in central Siberia during this spring and early summer has probably been a decisive factor in the melting of the coastal ice, especially in the Laptev. 

As to floes, yesterday ArcticMelt, in Reply #2229, showed a sequence of photos of a very large floe just 'dissolving' in the Laptev.  So the sea itself, which has been basking in the 24 hour midsummer sun, appears to be unusually warm.

The associated Siberian wildfires have also been epic in their extent, and these may have dumped more soot than usual on the coastal ice, accelerating the melting.     


On another topic, I am struck this year by the apparent near total scouring of remnant coastal ice and drifting floes in the Southern Kara and Laptev.  I seem to recall these areas usually leaving lingering coastal remnants behind after melt out until later in the melt season.  Even factoring in the Laptev disaster does this seem unusual to anyone else?

Yes, it is my first post, will try not to be too ignorant!
« Last Edit: July 06, 2020, 12:42:18 PM by Pagophilus »
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JayW

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Re: The 2020 melting season
« Reply #2270 on: July 06, 2020, 12:42:49 PM »
 10 day ice coverage delta from the ECMWF (requires a click).  Second attachment is the forecast for today from from 10 days ago.
https://weather.us/model-charts/euro/2020062612/north-pole-zoom1/ice-ocean-lake/20200706-1200z.html

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be cause

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Re: The 2020 melting season
« Reply #2271 on: July 06, 2020, 12:59:36 PM »
What do you think, what is the chance that melting could reach North Pole this year from the Russian side?

  or Greenland ?

I was very confident in 2016 and then the melting season stalled , as did the freezing season . A cool August can change everything . But this year has a very different feel thus far .

 Could that 977mb 'storm' way out at 384 hrs be replaced by a 1025+ high in the next forecast ? It has been known to happen ! :) b.c.
 
ps 1030+ ! .. still plenty of time for a storm or few .. more melt in the meantime ...
« Last Edit: July 06, 2020, 01:14:25 PM by be cause »
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 + 2 = 2021 + 1 =  ' if only we could have seen it coming ' ...

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Re: The 2020 melting season
« Reply #2272 on: July 06, 2020, 01:03:51 PM »
It probably won't come as a shock to discover that melt ponds are ponding is currently visible on MODIS all the way to the Pole, and holes are appearing in the sea ice at 85N and beyond:

https://go.nasa.gov/3f73ZX4

 
« Last Edit: July 06, 2020, 02:34:36 PM by Jim Hunt »
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Re: The 2020 melting season
« Reply #2273 on: July 06, 2020, 01:21:57 PM »
indeed Jim .. also a great day to look back at 2013 .. it looked like the end of the world in comparison to today .. yet it has become 'just another year' . b.c.
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 + 2 = 2021 + 1 =  ' if only we could have seen it coming ' ...

Pagophilus

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Re: The 2020 melting season
« Reply #2274 on: July 06, 2020, 01:48:22 PM »
It probably won't come as a shock to discover that melt ponds are currently visible on MODIS all the way to the Pole, and holes are appearing in the sea ice at 85N and beyond:

https://go.nasa.gov/3f73ZX4

Jim,
Inexperience asking here and I would really like to learn ... what are the meltponds on these images?   The upper image which includes shows 'marbling' with slightly darker, bluer 'patches', often shaped like rounded oblongs.  Are those the meltponds? 
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Pagophilus

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Re: The 2020 melting season
« Reply #2275 on: July 06, 2020, 01:57:49 PM »
indeed Jim .. also a great day to look back at 2013 .. it looked like the end of the world in comparison to today .. yet it has become 'just another year' . b.c.

I am glad you posted this, providing some perspective.  The weird thing is that most of us do not really want to see the ice plummet, but there is something riveting about the spectacle.

I went back and fished up this random remark from another thread here, made in 2013.  I am not attributing it ... I think that would be unfair.

"At this point...most people who visit this board often (which includes me) think the Arctic ice sheet is gone within 2 - 5 years (I think it is summer of 2015 or 2016)."


« Last Edit: July 06, 2020, 02:27:35 PM by Pagophilus »
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blumenkraft

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Re: The 2020 melting season
« Reply #2276 on: July 06, 2020, 02:00:27 PM »
The upper image which includes shows 'marbling' with slightly darker, bluer 'patches', often shaped like rounded oblongs.

Those are the areas containing the most obvious melt ponds. The first image in Jims post is zoomed out.

Quote
Are those the meltponds?

The second image is zoomed in, showing the blue ponds in better detail.

BTW, the structures you are seeing are cracks that allow liquid water to drain. I made a Sentinel 2 GIF where it starts with an extreme zoom in and zooms out. Click GIF to play.
« Last Edit: July 06, 2020, 02:13:45 PM by blumenkraft »

Pagophilus

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Re: The 2020 melting season
« Reply #2277 on: July 06, 2020, 02:10:05 PM »
The upper image which includes shows 'marbling' with slightly darker, bluer 'patches', often shaped like rounded oblongs.

Those are the areas containing the most obvious melt ponds. The first image in Jims post is zoomed out.

Quote
Are those the meltponds?

The second image is zoomed in, showing the blue ponds in better detail.

Thank you -- very helpful to me!  Blumenkraft, you make the gifs that keep on giving!   ;)
« Last Edit: July 06, 2020, 02:30:47 PM by Pagophilus »
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Jim Hunt

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Re: The 2020 melting season
« Reply #2278 on: July 06, 2020, 02:33:41 PM »
The upper image which includes shows 'marbling' with slightly darker, bluer 'patches', often shaped like rounded oblongs.  Are those the meltponds?

Perhaps I should choose my language more carefully? As BK points out, at that resolution individual melt ponds aren't going to be resolvable. How about "melt ponding" instead?

Compare and contrast with the same area a week ago:

https://go.nasa.gov/2Z31L5t

The "marbling" you refer to reveals that surface melting has set in since then.
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Re: The 2020 melting season
« Reply #2279 on: July 06, 2020, 02:42:06 PM »
A great day to look back at 2013 .. it looked like the end of the world in comparison to today .. yet it has become 'just another year' . b.c.

There were certainly many more "holes appearing in the sea ice at 85N and beyond" in 2013. However I don't recall "melt ponding at the North Pole" at the beginning of July? See an image I recorded earlier:

https://GreatWhiteCon.info/resources/arctic-sea-ice-images/summer-2013-images/#CAB
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Re: The 2020 melting season
« Reply #2280 on: July 06, 2020, 02:58:19 PM »
indeed Jim .. also a great day to look back at 2013 .. it looked like the end of the world in comparison to today .. yet it has become 'just another year' . b.c.

2013 was protected by the outer ice being slow to melt therefore all the dispersion that occurred that year did not come into play but it was a close run thing by the end of August as the CAB ice was full of holes quite extensively by then.

We shall see if this year starts to develop alot of dispersion in the CAB ice but one thing for(almost) sure, the ice edge on the Siberian side will probably be similar to 2007 where most of the ice edge was at 85 degrees north. I do believe the ice may have a similar pattern to 2007 in that there is more ice towards the Beaufort but very little ice on the Siberian side and we won't have any tongue of ice clinging on in the Laptev therefore I give a 70%.chance we will finish below 4 million this year which is significant enough for me

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Re: The 2020 melting season
« Reply #2281 on: July 06, 2020, 03:01:34 PM »
The upper image which includes shows 'marbling' with slightly darker, bluer 'patches', often shaped like rounded oblongs.  Are those the meltponds?

Perhaps I should choose my language more carefully? As BK points out, at that resolution individual melt ponds aren't going to be resolvable. How about "melt ponding" instead?

The "marbling" you refer to reveals that surface melting has set in since then.

Thank you -- I am learning.  I was certainly not intending to be critical of your terms -- you are the expert and not I. 

I had also gone back to 2013 and quickly manipulated the Worldview image from July 6, upping contrast.  It sure looked alarming, but as you say, there was no meltponding, and the icecap recovered somewhat.

IMO, one other thing 2013 highlights is the effects of a previous really bad year (2012) can have on the subsequent year.  Something to think of for 2021 if this melting season unfolds as it seems to be doing right now.  Given a warming earth, we are unlikely to be as lucky as we were in 2013.
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Re: The 2020 melting season
« Reply #2282 on: July 06, 2020, 03:35:33 PM »
you make the gifs that keep on giving!   ;)

Aww, thank you! <3

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Re: The 2020 melting season
« Reply #2283 on: July 06, 2020, 04:40:04 PM »
https://twitter.com/ZLabe/status/1280136370845958145

Quote
Comparing 2020 and 2012 sea ice extents in the Laptev Sea (near Siberia; #Arctic)


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Re: The 2020 melting season
« Reply #2284 on: July 06, 2020, 04:43:14 PM »
Smorgasbord of melting going on:

Blue ice all around in the fast ice of Severnaya Zemlya, melting streamers spreading in the Eastern Kara Sea. 
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Re: The 2020 melting season
« Reply #2285 on: July 06, 2020, 06:16:24 PM »
Really shocking stuff to see all around. I can’t say there is one single feature to me that is a complete “surprise,” for lack of a better term, but when the sum of the components are taken together it’s hard not to be in awe at this season. I will say the Beaufort Sea’s ice retention thus far has been the single feature I had not anticipated. With that said, it’s quite apparent just how much warmth from the ocean/bottom melt on from the Atlantic is cutting into the ice near Wrangle Island. I think once more areas open up in the Beaufort it will begin to mirror the rest of the pack.

It’s looking like more ice is beginning to breakup in the CAA so really nowhere is safe. I will keep an eye out to see how the mega crack confintues to evolve this season.

pls!

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Re: The 2020 melting season
« Reply #2286 on: July 06, 2020, 06:43:50 PM »
indeed Jim .. also a great day to look back at 2013 .. it looked like the end of the world in comparison to today .. yet it has become 'just another year' . b.c.

2013 was protected by the outer ice being slow to melt therefore all the dispersion that occurred that year did not come into play but it was a close run thing by the end of August as the CAB ice was full of holes quite extensively by then.

When one looks at the entirety of the 7 seas of the High Arctic a complementary story emerges. I attach a table of High Arctic sea ice area as at the 5th July. 2013 area is 1.17 million km2, 17.9% above the 2020 area for this date, and 19th lowest. How contrary was 2013 to show such high signs of melt in the Central Arctic Sea while the High Arctic seas outer ring do not.
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Re: The 2020 melting season
« Reply #2287 on: July 06, 2020, 06:59:55 PM »
A closer look at Arctic SST anomalies from DMI @ http://ocean.dmi.dk/satellite/index.uk.php
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Re: The 2020 melting season
« Reply #2288 on: July 06, 2020, 08:34:23 PM »
10 days GFS temp anomaly forecast.

https://climatereanalyzer.org/wx_frames/gfs/ds/gfs_arc-lea_t2anom_10-day.png

Conditions forecast to remain relatively benign for the Beaufort sea region and ten days takes us through the peak insolation window.

Beaufort area is at 670k km2, now about 6 weeks behind last year's pace. What's the ceiling on how much ice could conceivably remain in this sea at the minimum? 300k? 400k?

JNap

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Re: The 2020 melting season
« Reply #2289 on: July 06, 2020, 09:02:04 PM »
The latest ECM forecast (July 6, 12z) shows that the high pressure continues to stay relatively strong for not only the next 5 days, but for days 6-9 as well.  Looks like this high insolation and resulting CAB melting will continue.

https://www.tropicaltidbits.com/analysis/models/?model=ecmwf&region=nhem&pkg=z500_mslp&runtime=2020070612&fh=0
« Last Edit: July 06, 2020, 09:45:50 PM by JNap »
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romett1

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Re: The 2020 melting season
« Reply #2290 on: July 06, 2020, 09:24:55 PM »
3-day average 10m wind speed forecast (GFS) - today's forecast vs Sunday's forecast. Seems like more wind towards North Pole, Fram Strait.

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Re: The 2020 melting season
« Reply #2291 on: July 06, 2020, 09:57:51 PM »
The latest ECM forecast (July 6, 12z) shows that the high pressure continues to stay relatively strong for not only the next 5 days, but for days 6-9 as well.  Looks like this high insolation and resulting CAB melting will continue.

Fortunately, the surface temperatures are forecast to ease off in a few days. The perfect storm of melting conditions will be a little less perfect.

https://climatereanalyzer.org/wx/fcst/#gfs.arc-lea.t2

Sublime_Rime

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Re: The 2020 melting season
« Reply #2292 on: July 06, 2020, 11:32:52 PM »
Quote

Fortunately, the surface temperatures are forecast to ease off in a few days. The perfect storm of melting conditions will be a little less perfect.

https://climatereanalyzer.org/wx/fcst/#gfs.arc-lea.t2

I hope the GFS run you cite is correct, but I fear that the Euro has been more accurate at predicting both the high pressure intensity and the temperature anomalies these last two weeks that I have been following both more closely (GFS has been running cool and lower pressure, Euro slightly hot and above pressure). Below is what the Euro 12Z says about d5, d7 and d9. Only the Beaufort and parts of CAA are spared the heat. The GEM corroborates pretty closely w/r/t heat position, but is even worse in magnitude (of heat and HP). I also attached GEM 12Z d9.
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jdallen

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Re: The 2020 melting season
« Reply #2293 on: July 06, 2020, 11:33:03 PM »
The latest ECM forecast (July 6, 12z) shows that the high pressure continues to stay relatively strong for not only the next 5 days, but for days 6-9 as well.  Looks like this high insolation and resulting CAB melting will continue.

Fortunately, the surface temperatures are forecast to ease off in a few days. The perfect storm of melting conditions will be a little less perfect.

https://climatereanalyzer.org/wx/fcst/#gfs.arc-lea.t2
I'm afraid I don't see it.  As long as we have surface temps at or above zero and insolation, the havoc will continue unabated.  I see no respite.
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uniquorn

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Re: The 2020 melting season
« Reply #2294 on: July 06, 2020, 11:37:49 PM »
the motion of #103 has me rethinking my notions of Beaufort  Sea ice motion, is a bee line dash along the coast like that common?
The sea ice age animation here gives a reasonable indication of ice movement over the last 20 years

Phoenix

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Re: The 2020 melting season
« Reply #2295 on: July 06, 2020, 11:57:44 PM »
The latest ECM forecast (July 6, 12z) shows that the high pressure continues to stay relatively strong for not only the next 5 days, but for days 6-9 as well.  Looks like this high insolation and resulting CAB melting will continue.

Fortunately, the surface temperatures are forecast to ease off in a few days. The perfect storm of melting conditions will be a little less perfect.

https://climatereanalyzer.org/wx/fcst/#gfs.arc-lea.t2
I'm afraid I don't see it.  As long as we have surface temps at or above zero and insolation, the havoc will continue unabated.  I see no respite.

So, you're of the opinion that a surface temperature of 0.5C and 2.0C will yield the same melt rate, all other factors being equal?

My sense is that a stronger temperature gradient between the ice and surrounding air will lead to a faster rate of energy transfer.

thejazzmarauder

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Re: The 2020 melting season
« Reply #2296 on: July 07, 2020, 12:07:00 AM »
I’m hesitant to suggest it, as I’m not a SME and am aware of the detrimental impact of hyperbole re: climate, but is it possible that the next ~5 days could be the worst stretch for ice retention in recorded history? And I don’t only mean extent/area drops, as the effects of any preconditioning (e.g. surface melt over majority of inner basin) won’t be fully realized until later in the season. I do understand the subjective nature of this question, and am sure the 2012 GAC, while a very different type of event, will have some champions.

jdallen

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Re: The 2020 melting season
« Reply #2297 on: July 07, 2020, 12:19:32 AM »
<snippage>
<snippage>
I'm afraid I don't see it.  As long as we have surface temps at or above zero and insolation, the havoc will continue unabated.  I see no respite.

So, you're of the opinion that a surface temperature of 0.5C and 2.0C will yield the same melt rate, all other factors being equal?

My sense is that a stronger temperature gradient between the ice and surrounding air will lead to a faster rate of energy transfer.
The direct transfer of heat from atmosphere to ice is trivial compared to that delivered by insolation. 

The difference in heat passed to the ice directly from atmosphere at 5c is very small compared to 0c. 

This lack of impact ties back to the total enthalpy available in the air vs the phase change energy required to melt the ice.  The lack of available energy in the air is why surface temperatures even in summer tend to stay pegged at close to 0C, even over open water (especially in fact), as any available heat rapidly gets transferred.  Temperatures much above that are unusual, and typically require extensive melt ponds (which can be quite a bit warmer than the underlying sea water), or massive influxes of heat from farther south.

Even then, the amount of heat being carried doesn't stand up significantly to that from sunlight.
Without insolation, melt rates even at 10c would be measured in mm/day, and we were no where near that.  There isn't enough heat in the atmosphere, and it can't transfer fast enough.
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Phil42

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Re: The 2020 melting season
« Reply #2298 on: July 07, 2020, 12:20:32 AM »
Some big cracks appearing in the Perry Channel today, indicating the start of the collapse of fast ice in that region. Looking at past years on WorldView, this is not unusual for this time of the year. Still something to keep an eye on given the overall state of the ice pack.

Michael Hauber

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Re: The 2020 melting season
« Reply #2299 on: July 07, 2020, 12:25:05 AM »
There have been a couple comments about a low following on from the current conditions, which does seem to be showing somewhat consistently in EC and GFS for week 2.  If we do get a low pressure it will depend on how long it persists.  Both 2010 and 2011 had blistering starts to summer with strong high pressure systems and setting new records for melt at that time of year.  However in both cases conditions abruptly switched to low pressure and cloudy conditions and melt abruptly slowed down.

If we get a low pressure for a short period it could disperse the central ice and create weaknesses.  And if we have follow up sunshine these weaknesses would see enhanced melt, which I think was a critical factor in 2012's melt season.  It may also speed up the melt on the weak and basically doomed ice in the periphery, and adjacent to the periphery with some shocking weaknesses evident the Chukchii and Siberian sectors and some weakness also evident in the Beaufort.
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