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Jim Hunt

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Re: The 2020 melting season
« Reply #4400 on: August 02, 2020, 10:41:56 PM »
I wish I understood more of the dynamics which facilitated such a vast separation plus an ever-widening crack.

The recent reverse dipole?
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Frivolousz21

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Re: The 2020 melting season
« Reply #4401 on: August 03, 2020, 12:06:38 AM »
I made little animations using the NSIDC comparison tool comparing the remainder of the melting seasons 2012 and 2019 against the current state.

Wow  thanks for posting. 

That really puts things in perspective.

2020 is going to finish with less ice on the Atlantic/Laptev side for sure.

The CAA is going to melt out through the NW passage and somewhat even further north than that.

If 20/20 has more ice in the Beaufort than 2019 which is still way up in the air CAA will make up for it.

That leaves the Chukchi, ess, and Laptev fringes which I have no doubt will be worse than 2019.

The big question is how much of the interior pack is going to melt out?


Well its August  2nd and holes are opening up all over and in places we haven't seen in modern human history





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pearscot

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Re: The 2020 melting season
« Reply #4402 on: August 03, 2020, 12:15:46 AM »
It's nice to see several people are taking note of what's going above Greenland/the Lincoln Sea. This entire region just continues to surprise and I wish I understood more of the dynamics which facilitated such a vast separation plus an ever-widening crack.
This is today.  There is a lot going on.  Interesting swirls in the open areas extending north from Greenland.  Then there's the interesting feature in the lower right, and the subsequent waves propagating northward.  After seeing this gif from blumenkraft.
https://forum.arctic-sea-ice.net/index.php/topic,2649.msg277039.html#msg277039
I get the feeling the "plunger" action of the tide moving north through the Nares sends a wave that gets trapped along the coast due to coriolis. It's then forced upwards due to bathymetry, creating the swirl, with some of the wave reflect back, but much of it continuing poleward.
There is a lot of "sloshing" in the Lincoln Sea area.
Contrast boosted.  Click to run.

Wow, thank you for making that! That is so interesting to see that wave propagation toward the Atlantic. It really shows how dynamic of a region even the 'static' parts look.

I forget who said it, but it's totally true that this is a new melting frontier at this point. I mean it's impossible to notice a 30 mile stretch of open water in a place which normally has ice all year. I think it would be an amazing picture to take if from the northern Greenland coast looking due north.
pls!

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Re: The 2020 melting season
« Reply #4403 on: August 03, 2020, 12:17:36 AM »
The Crack N. of G'land is becoming a regular feature .. click back thru the last few years on WV .. today is a good day so to do ..
  More concerning this year is the state of the ice between G'land and the pole .. clear view all the way today . Few significant floes , lots of mush and quite a lot of open water .
        https://go.nasa.gov/3k7KjVF  .. b.c.
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 + 2 = 2021 + 1 =  ' if only we could have seen it coming ' ...

Jim Hunt

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Re: The 2020 melting season
« Reply #4404 on: August 03, 2020, 12:20:59 AM »
I think it would be an amazing picture to take if from the northern Greenland coast looking due north.

Here's one looking in the opposite direction:
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Jim Hunt

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Re: The 2020 melting season
« Reply #4405 on: August 03, 2020, 12:26:45 AM »
More concerning this year is the state of the ice between G'land and the pole .. clear view all the way today . Few significant floes , lots of mush and quite a lot of open water
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

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Re: The 2020 melting season
« Reply #4406 on: August 03, 2020, 12:26:57 AM »
This seems important.

Maybe if we are lucky, Ossifrage will get some time to check in and let us know what he is seeing.

The ice north of Greenland and the CAA is really getting hammered this year. Historically, it was assumed that the ice north of Greenland and the CAA would be the last to go. This year, it looks possible there could be an ice free shipping route all the way from the Fram, north of Greenland and the CAA, into the Beaufort.

Does anyone have the CAB detaching from North America on their 2020 bingo card?

Frivolousz21

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Re: The 2020 melting season
« Reply #4407 on: August 03, 2020, 12:29:08 AM »
The crack North of Gis is rare and indicates lots of melt in the region.

But the open water North of there within the ice pack is truly AMAZING.

THESE ARE OPENINGS THAT ARE ICE FREE THAT ARE UPWARDS OF 10-30 KILOMETERS WIDE.

This is special because it indicates that ice they're actually melted out which is amazing.


According to piomas the ice North of the crack where the open water is building as of 7/15/20 was between 2-2.75M thick

Regardless this ice was likely 3M thick in early June.

Unless its ice that was near Svalbard but I doubt that
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Frivolousz21

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Re: The 2020 melting season
« Reply #4408 on: August 03, 2020, 12:30:55 AM »
This seems important.

Maybe if we are lucky, Ossifrage will get some time to check in and let us know what he is seeing.

The ice north of Greenland and the CAA is really getting hammered this year. Historically, it was assumed that the ice north of Greenland and the CAA would be the last to go. This year, it looks possible there could be an ice free shipping route all the way from the Fram, north of Greenland and the CAA, into the Beaufort.

Does anyone have the CAB detaching from North America on their 2020 bingo card?

And that will never reform.

Whatever the new edge is at the minimum it will break there from the main pack now
I got a nickname for all my guns
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a two shot that I call Tupac
and a dirty pistol that love to crew hop
my TEC 9 Imma call T-Pain
my 3-8 snub Imma call Lil Wayne
machine gun named Missy so loud
it go e-e-e-e-ow e-e-e-e-e-e-blaow

uniquorn

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Re: The 2020 melting season
« Reply #4409 on: August 03, 2020, 12:37:38 AM »
overlay of amsr2-uhh on to mercator(model) 0m ocean temperature. jul1-aug1. (9.5MB)

glennbuck

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Re: The 2020 melting season
« Reply #4410 on: August 03, 2020, 12:39:14 AM »
Ice Concentration/Thickness not looking good going forward to 7th August, projection from DMI. Thickness might not be accurate as it shows 2-3 Meter ice being melted in North Greenland. if that was happening there would not be much ice left by the middle of August! The 2m temperature anomaly in the Arctic today was 2.1 C above average.
« Last Edit: August 03, 2020, 01:49:38 AM by glennbuck »

Frivolousz21

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Re: The 2020 melting season
« Reply #4411 on: August 03, 2020, 12:49:49 AM »
It's nice to see several people are taking note of what's going above Greenland/the Lincoln Sea. This entire region just continues to surprise and I wish I understood more of the dynamics which facilitated such a vast separation plus an ever-widening crack.
This is today.  There is a lot going on.  Interesting swirls in the open areas extending north from Greenland.  Then there's the interesting feature in the lower right, and the subsequent waves propagating northward.  After seeing this gif from blumenkraft.
https://forum.arctic-sea-ice.net/index.php/topic,2649.msg277039.html#msg277039
I get the feeling the "plunger" action of the tide moving north through the Nares sends a wave that gets trapped along the coast due to coriolis. It's then forced upwards due to bathymetry, creating the swirl, with some of the wave reflect back, but much of it continuing poleward.
There is a lot of "sloshing" in the Lincoln Sea area.
Contrast boosted.  Click to run.

That's amazing and even more so  that the huge chunks of land fast ice have broken off from gis.

Historically those are between 6-15M thick.

Sometimes upwards of 30M thick.

They will likely never reform because the ice that replaces it will  be to thin to withstand  breaking off for many seasons.

The most immediate impact I would think besides possibly Coastal erosion will be the crack in the future along the land in the southern basin will be wide enough that warmer water will probably form there and help eat away at the thickest ice every summer.


Although this summer has seen more southerly winds coming out of the CAA in Greenland then I can remember since at least 2007
I got a nickname for all my guns
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a two shot that I call Tupac
and a dirty pistol that love to crew hop
my TEC 9 Imma call T-Pain
my 3-8 snub Imma call Lil Wayne
machine gun named Missy so loud
it go e-e-e-e-ow e-e-e-e-e-e-blaow

JamesW

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Re: The 2020 melting season
« Reply #4412 on: August 03, 2020, 01:34:20 AM »
Jaxa AMSR2 Arctic Sea Ice Average Thickness graph from our fellow Wipneus now in record territory for this date.

Worth watching as the next few days go by.....

uniquorn

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Re: The 2020 melting season
« Reply #4413 on: August 03, 2020, 01:35:53 AM »
amsr2-uhh for 2012 is available from aug1. I tried hard to replicate this comparison of 2020 with 2012 but A-Team's is better. Passing it on unmodified.
Green is open water for both years
Orange, open water in 2020
Pink, open water in 2012.
pixel count overlayed onto greenland
click to run

colchonero

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Re: The 2020 melting season
« Reply #4414 on: August 03, 2020, 01:41:52 AM »
3m thick ice, did not melt in a month. Either it wasn't 3m thick, or it didn't melt  out. Especially not 2,5m in 15 days.

Forecast is very far from disastrous for ice. Ice condition is the main problem at many places, and just because of that we could see some bigger drops in closer future.

glennbuck

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Re: The 2020 melting season
« Reply #4415 on: August 03, 2020, 02:18:40 AM »
More concerning this year is the state of the ice between G'land and the pole .. clear view all the way today . Few significant floes , lots of mush and quite a lot of open water

It looks like a large section will break off and drift into the Barents sea!

interstitial

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Re: The 2020 melting season
« Reply #4416 on: August 03, 2020, 03:10:17 AM »
These thickness graphs, while useful, never have materialized in a complete meltout. There are so many other factors like insulation, ocean depth and currencies. I suppose I'm not too far off with my proposal. Though the Arctic is always good for a surprise ...
This statement confuses me. Complete melt out of what? Your quadrilateral showed little loss of thin ice on the Siberian side and much greater loss in the Beufort. I just think close to the ice edge on the Siberian side is unlikely. That does not mean I expect it to melt to the pole.

be cause

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Re: The 2020 melting season
« Reply #4417 on: August 03, 2020, 03:12:51 AM »
looks like ice is ready to 'go with the flow ' everywhere .. even the <1000mb low crossing the basin will be stirring the pot as it passes by .
   All changes of wind direction and speed impact the ice .
The pack is getting torn to shreds and that will continue under a variable weather pattern like that forecast for the next week . I said before that what the ice needed in August was 'no weather' .. the forecast is for lots of weather . Not high drama , but likely ' high impact ' .
  I had hoped the lack of floes embedded in the ice matrix would help it move as one better as floes respond to changes in momentum more slowly so tear up the mush around them .
  ^^ the average thickness graph tells the tale .. melt is ongoing and massive . We are losing volume . b.c.
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NotaDenier

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Re: The 2020 melting season
« Reply #4418 on: August 03, 2020, 03:40:27 AM »
It's nice to see several people are taking note of what's going above Greenland/the Lincoln Sea. This entire region just continues to surprise and I wish I understood more of the dynamics which facilitated such a vast separation plus an ever-widening crack.
This is today.  There is a lot going on.  Interesting swirls in the open areas extending north from Greenland.  Then there's the interesting feature in the lower right, and the subsequent waves propagating northward.  After seeing this gif from blumenkraft.
https://forum.arctic-sea-ice.net/index.php/topic,2649.msg277039.html#msg277039
I get the feeling the "plunger" action of the tide moving north through the Nares sends a wave that gets trapped along the coast due to coriolis. It's then forced upwards due to bathymetry, creating the swirl, with some of the wave reflect back, but much of it continuing poleward.
There is a lot of "sloshing" in the Lincoln Sea area.
Contrast boosted.  Click to run.

That's amazing and even more so  that the huge chunks of land fast ice have broken off from gis.

Historically those are between 6-15M thick.

Sometimes upwards of 30M thick.

They will likely never reform because the ice that replaces it will  be to thin to withstand  breaking off for many seasons.

The most immediate impact I would think besides possibly Coastal erosion will be the crack in the future along the land in the southern basin will be wide enough that warmer water will probably form there and help eat away at the thickest ice every summer.


Although this summer has seen more southerly winds coming out of the CAA in Greenland then I can remember since at least 2007

Your comment made me look a little closer friv. That was actually a floating ice tongue of the Milne? glacier. It was more like 100m thick (in the 80s) and was the second largest ice Shelf in the attic. So that’s actually a pretty substantial iceberg.

https://en.wikipedia.org/wiki/Milne_Ice_Shelf

https://wirl.carleton.ca/research/ice/ice-shelves/milne-ice-shelf/

https://www.rcinet.ca/en/2013/08/09/eye-on-the-arctic-understanding-the-milne-ice-shelf/

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2011JF002074

Edit the shelf was thinner but still pretty thick and held back a epishelf lake. Which I had to read up on. Also the scientists camp and instruments were destroyed but luckily they were not there.

Oren you may want to move this?
« Last Edit: August 03, 2020, 03:54:43 AM by NotaDenier »

Rod

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Re: The 2020 melting season
« Reply #4419 on: August 03, 2020, 04:41:10 AM »
The information about the Milne ice shelf collapse was released today, and came from the ECCC Canadian Ice Service.

It is relevant to this melting season. 

If you want to start another thread about the historical properties of the ice shelf, that is good too! But, the current information should be left here as an important part of this melt season.

oren

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Re: The 2020 melting season
« Reply #4420 on: August 03, 2020, 04:59:15 AM »
Indeed Rod, I was just about to post the same. The calving shows something important about the melting season, and has to do with warm temps, wind from the south, and the Crack. I have cross-posted a couple of the posts to Ice Shelves /Ward Hunt Ice Shelf / Ellesmere Island / Canada, please continue the specific Milne discussion there.

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Re: The 2020 melting season
« Reply #4421 on: August 03, 2020, 05:30:25 AM »
Does anyone have the CAB detaching from North America on their 2020 bingo card?

Time for a new thread “When will the Northwest Sea Route open”?

Pmt111500

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Re: The 2020 melting season
« Reply #4422 on: August 03, 2020, 06:19:42 AM »
More concerning this year is the state of the ice between G'land and the pole .. clear view all the way today . Few significant floes , lots of mush and quite a lot of open water

It looks like a large section will break off and drift into the Barents sea!
Yep, tried to track the border of untangled ice floes across the arctic. Resolution is not sufficient and clouds over the pole prevented tracking of the cracks and seeing where mutual hits have rounded the floes

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Re: The 2020 melting season
« Reply #4423 on: August 03, 2020, 07:11:17 AM »
Two posts, because I have 5 images.

I thought it would be instructive first to look at the evolution of a section of the Laptev, which pretty much melted out completely in July.

Images from the 1st, 12th, 20th and 28th.

The image in the message immediately following will be a section of the Beaufort that actually contains areas of ice in much the same state as that at different junctures in the Laptev.
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jdallen

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Re: The 2020 melting season
« Reply #4424 on: August 03, 2020, 07:12:57 AM »
Now immediately following, the shot of a larger section of the Beaufort.

My take away is, given sufficient time, at least half the ice visible will be gone in 3 weeks, and most by the end of the month.

What it gives us here, is a visual reference point for condition.  Pick a date from what we see in the Laptev that approximates the area you are looking at, and that is probably a good reference for what you'll be looking at in "X" number of days later.

It's not good news, especially if a dipole or other activity continues to stir the ice cubes.

The heat budget to kill the ice in the Beaufort and Chukchi is there.  We're in a race to see when the out vs inbound heat exchange hits neutral so the bottom melt stops.

As it is, we still have about 10 more days of top melt, especially at the lower latitudes - like on the Pacific side.  That difference in latitude will make a qualitative difference if you are looking at similar ice from 2013 or 14 north of 80 on the Atlantic side - which was nearly as bad.
« Last Edit: August 03, 2020, 07:18:53 AM by jdallen »
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binntho

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Re: The 2020 melting season
« Reply #4425 on: August 03, 2020, 07:22:28 AM »
Interesting swirls in the open areas extending north from Greenland.  Then there's the interesting feature in the lower right, and the subsequent waves propagating northward.  After seeing this gif from blumenkraft.
https://forum.arctic-sea-ice.net/index.php/topic,2649.msg277039.html#msg277039
I get the feeling the "plunger" action of the tide moving north through the Nares sends a wave that gets trapped along the coast due to coriolis. It's then forced upwards due to bathymetry, creating the swirl, with some of the wave reflect back, but much of it continuing poleward.
There is a lot of "sloshing" in the Lincoln Sea area.
Contrast boosted.  Click to run.

Blumenkrafts post is indeed interesting, the tidal "breathing" is very clear. But remember that the tides go both ways, and the general current in the Nares is to the south. It's a bit like the propagation of electrons in an alternative current - the electrons slosh back and forth with every Hertz but on average they always flow in the direction of the current.

So if there is tidal movement of water going north, twice daily, there should be a corresponding and equal movement of water going south, twice daily. Somehow everybody who thinks they see large tidal movements seem to forget about this basic fact.

So how big are the tides in the Nares, and how much water is actually being moved back and forth? This paper was published by AGU: Propagation and Vertical Structure of the Tidal Flow in Nares Strait and makes for very interesting reading.

And the image of tidal effect in the Arctic is a keeper - I've been looking for an image like his for a long time, see below. The tidal effect in the Arctic is very similar to that seen in the Mediterranean, ranging from 5 to 15 cm. This is too small to be noticeable except where straits create chokepoints - as does the Messina Strait, leading to an occasional narrow current (a few tens of meters accross) down the Sicilian coast (i.e. the current is normally not noticeable but I have experienced days of surprisingly strong movement - perhaps phase related?)

So the Nares strait should similarly experience tidal currents. Apparently, a standig wave in the middle of the strait has the biggest tidal effect (up to 1.5 meters). The peak currents seem to have a wide range depending on depth, from 30 down to 5 cm/s. For simplicity's sake I estimate one hour at 15cm/s for the peak flow which shouldl be very close to total flow (i.e. the 6 hour period between tidal turns).

With an average depth of 250 meters and cross section of 35 km, one hour at 15 cm/s will move appr. 5 km3 one way twice daily. And twice daily, the same amount of water moves in the opposite direction. Not really that much and nothing that should be expected to have any significant effect outside of the Nares strait itself except possibly as a narrow current along the Greenland coast as Blumenkraft has seen and demonstrated on occasion.

So do not expect the tides to have any effect whatsoever om the movement of ice outside of the Nares strait and possibly along the northern Greenland coast. But not in the Arctic proper.
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Re: The 2020 melting season
« Reply #4426 on: August 03, 2020, 09:18:07 AM »
The leads in the north of Greenland/Lincoln are worsening.

Freegrass

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Re: The 2020 melting season
« Reply #4427 on: August 03, 2020, 09:21:34 AM »
Latest Five Day Forecast
Wind + Temp @ Surface
Large GiF!
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...

Pmt111500

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Re: The 2020 melting season
« Reply #4428 on: August 03, 2020, 09:24:59 AM »
Latest Five Day Forecast
Wind + Temp @ Surface
Large GiF!
The Great Rip-Off of 2020. Intersting to see if Arctic has any solid large ice surface after this. Probably going back into hiberna... Sorry, ....aestivation again, keeping an eye on this though.
« Last Edit: August 03, 2020, 09:32:23 AM by Pmt111500 »

glennbuck

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Re: The 2020 melting season
« Reply #4429 on: August 03, 2020, 09:39:49 AM »
Lincoln Sea, August 2nd, open water where the Multi year thickest ice used to be!
« Last Edit: August 03, 2020, 07:14:33 PM by glennbuck »

Freegrass

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Re: The 2020 melting season
« Reply #4430 on: August 03, 2020, 10:57:11 AM »
Latest Five Day Forecast
Wind + Temp @ Surface
Large GiF!
The Great Rip-Off of 2020. Intersting to see if Arctic has any solid large ice surface after this. Probably going back into hiberna... Sorry, ....aestivation again, keeping an eye on this though.
What this melting season will prove or disprove IMHO is if a compact ice pack is more prone to melt than a dispersed pack.

Because the pack was so small and compacted, most of the energy went into the surrounding seas that had no ice left to melt, and not in pockets of water in between floes - as would happen with a more dispersed pack.

So did a more compact ice pack reflect more of the sun's energy? And is all we have left now for the remainder of the season the energy in open water that will get cooled rapidly as insolation ends and the ice edge melts?

We'll know in a few weeks I guess...
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...

Mark Tough

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Re: The 2020 melting season
« Reply #4431 on: August 03, 2020, 11:40:26 AM »


"We've long known that as climate change takes hold, the effects would be especially pronounced in the Arctic," said Serreze. "But the death of those two little caps that I once knew so well has made climate change very personal. All that's left are some photographs and a lot of memories."

https://phys.org/news/2020-07-canadian-ice-caps-scientific.html
[/quote]

Thanks for posting Freegrass - sad but just so indicative of all things melt.

Slightly off topic, I clicked through to your Phys Org link and couldn't believe the comments section. Rampant deniers and the science swamped in the rude and banal... Thank you Oren & Neven for you moderation, your part art part science approach is appreciated and oh so necessary.

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Re: The 2020 melting season
« Reply #4432 on: August 03, 2020, 12:21:34 PM »
Sorry I don't have the mean to fully exploit the dataset for MERRA reanalysis, but as an illustration. For June, net surface shortwave (~ solar) flux was high, but not as high as in 2019. Last year was quite extraordianry from this point of view. The first map is for 2020, the second is for 2019 and the third is the difference, 2020 minus 2019. We will see what did happened in July (MERRA data are available around the 20th for the preceding month).

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Re: The 2020 melting season
« Reply #4433 on: August 03, 2020, 12:22:20 PM »
My take on the loss of ice north of Greenland is tidally forced Atl. entering by Svalbard enhancing the existing current towards Nares of the same waters but pushing more forcefully along the shelf creating turbulence/vortices which overspill onto the shelf. Not all of it makes it through to the Canadian side but may force it's way through in the two or three days left of peak tidal movement, after that the rotating ice should close the gap. Similarly the lighter fraction of Atl. waters is creating more turbulence along Barents shelf as it pushes east causing more melt/retreat there.

uniquorn

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Re: The 2020 melting season
« Reply #4434 on: August 03, 2020, 12:23:45 PM »
update on melt north of greenland using amsr2-uhh, jul26-aug2
chaotic mix of wind, currents and tides in the Fram Strait/Greenland Sea shown by mosaic buoy drift, jul20-aug3
« Last Edit: August 03, 2020, 12:32:52 PM by uniquorn »

binntho

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Re: The 2020 melting season
« Reply #4435 on: August 03, 2020, 12:43:00 PM »
My take on the loss of ice north of Greenland is tidally forced Atl. entering by Svalbard enhancing the existing current towards Nares of the same waters but pushing more forcefully along the shelf creating turbulence/vortices which overspill onto the shelf. Not all of it makes it through to the Canadian side but may force it's way through in the two or three days left of peak tidal movement, after that the rotating ice should close the gap. Similarly the lighter fraction of Atl. waters is creating more turbulence along Barents shelf as it pushes east causing more melt/retreat there.
So how do your tidal currents fit in with the general currents in the area, i.e. the well-known West Spitzbergen current and the East Greenland current. Do those currents stop while your "tidally forced Atl." waters slosh about? In an area with practically no tidal effect? And how come that your tides only work one way?

EDIT: A quick and dirty search came up with this paper on the currents in the Fram strait, with direct measurments. No mention of tides, they apparently have no effect here (Deep Flow Variability Offshore South-West Svalbard (Fram Strait)).
« Last Edit: August 03, 2020, 12:52:14 PM by binntho »
because a thing is eloquently expressed it should not be taken to be as necessarily true
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oren

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Re: The 2020 melting season
« Reply #4436 on: August 03, 2020, 12:57:02 PM »
All, some requests:
Posts about tangential topics that still reflect on the season (e.g. small Canadian ice caps) should be kept short, with the main post going into the relevant thread as here it will get lost in a heartbeat.
Housekeeping posts are sometimes necessary and I can't always sort everything, so thanks. But when removing please repost to the style or posting guidelines threads, for all to see at later times.
Arguments on contentious scientific subjects (e.g. tides) should go in their appropriate threads. If someone makes a claim you think is wrong, quote and respond in that thread, with the option of a small note in this thread so people know a rebuttal has been made.

Jim Hunt

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Re: The 2020 melting season
« Reply #4437 on: August 03, 2020, 01:09:57 PM »
Sorry I don't have the mean to fully exploit the dataset for MERRA reanalysis

A fellow Panoply user by the look of it  :)

Can you provide a link to the data behind that visualisation? And any other data sources you access regularly. This is my favourite:

http://nomads.ncep.noaa.gov/pub/data/nccf/com/wave/prod/

TIA
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Jim Hunt

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Re: The 2020 melting season
« Reply #4438 on: August 03, 2020, 01:11:43 PM »
Chaotic mix of wind, currents and tides in the Fram Strait/Greenland Sea shown by mosaic buoy drift, jul20-aug3

Thanks uniquorn. Very enlightening!
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Thomas Barlow

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Re: The 2020 melting season
« Reply #4439 on: August 03, 2020, 01:22:08 PM »
« Last Edit: August 03, 2020, 01:27:56 PM by Thomas Barlow »

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Re: The 2020 melting season
« Reply #4440 on: August 03, 2020, 01:31:13 PM »
Sorry I don't have the mean to fully exploit the dataset for MERRA reanalysis

A fellow Panoply user by the look of it  :)

Can you provide a link to the data behind that visualisation? And any other data sources you access regularly. This is my favourite:

http://nomads.ncep.noaa.gov/pub/data/nccf/com/wave/prod/

TIA

I don't use a personal computer, and I don't have many option to plot and analyse data : excel and wathever can run without any installation, so there is only few options left  :D This is data from MERRA reanalysis, the most reliable reanalysis freely available for raditiative flux to my knowledge :

https://disc.gsfc.nasa.gov/datasets/M2TMNXRAD_5.12.4/summary

You need to register to download files, but it's all. There is also some delay, you have to wait the 20th for the most recent monthly data.
There is also data from the reanalysis from the NCEP/NCAR in near real time but it is a bit less reliable. And this year, I don't know the source of the problem, but it seems to me there is an inconsistency for radiative flux.

https://psl.noaa.gov/cgi-bin/db_search/SearchMenus.pl
https://psl.noaa.gov/cgi-bin/db_search/DBSearch.pl?Variable=Upward+Solar+Radiation+Flux&group=0&submit=Search
« Last Edit: August 03, 2020, 01:46:41 PM by aslan »

Freegrass

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Re: The 2020 melting season
« Reply #4441 on: August 03, 2020, 01:34:36 PM »
Latest Five Day Forecast
Wind @ Surface
Wind + Temp @ 850hPa
Wind @ 250hPa
Large GiFS!

Nares export is gonna get brutal this week, while the Beaufort will get its moment in the sun...
« Last Edit: August 03, 2020, 01:45:10 PM 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...

gerontocrat

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Re: The 2020 melting season
« Reply #4442 on: August 03, 2020, 02:05:04 PM »
This very recent paper says that it is Ocean Heat Transport  (OHT) that is more important than Atmospheric Heat Transport (AHT) in determining the ice edge. The maths in the paper is fierce.

SST's are really high over much of the ice edge.

RESEARCH ARTICLE| 21 JULY 2020
Impacts of Oceanic and Atmospheric Heat Transports on Sea Ice Extent

Quote
6. Conclusions
This work sought to understand the qualitative and quantitative impacts of oceanic and atmospheric heat transport on sea ice extent on climatic time scales. We presented an idealized, zonally averaged energy balance climate model that expands upon previous such models by a more sophisticated representation of OHT and some smaller modifications to the sea ice and atmospheric components. The model reproduces typical conditions in the Northern Hemisphere and sensitivity analyses were carried out relative to this reference state.

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 (found by varying the mixed layer diffusivity Ko). This higher sensitivity to oceanic than atmospheric heating is consistent with previous studies (Thorndike 1992; Singh et al. 2017)
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glennbuck

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Re: The 2020 melting season
« Reply #4443 on: August 03, 2020, 02:32:33 PM »
Open water around 40 miles from the North Pole. August 3rd
« Last Edit: August 03, 2020, 02:51:37 PM by glennbuck »

pauldry600

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Re: The 2020 melting season
« Reply #4444 on: August 03, 2020, 02:36:31 PM »
Christ,

Hadnt looked at ice for a couple of days. Looked at Bremen Graphs today. That ice is in rank bad order isnt it. Never seen the whole pack look so bad. There are no good bits. If it was late June thered be nothing by September but its early August. Are we late enough for it to hold? That bit off the top of Greenland really alarmed me. A couple of years ago the North of Greenland was untouchable to melt. This is getting worse than serious.

wallen

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Re: The 2020 melting season
« Reply #4445 on: August 03, 2020, 02:48:02 PM »
Curious to know if anyone uses the Geographic view on Worldview  to look at the Arctic. The different angle frequently gives a spectacular view that is often obscured by cloud from the Arctic view. The view for 2/8 was a great example. It showed many holes in the ice pack that were otherwise difficult to see.

binntho

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Re: The 2020 melting season
« Reply #4446 on: August 03, 2020, 03:02:28 PM »
The growing gap ... July 23 - August 2.
because a thing is eloquently expressed it should not be taken to be as necessarily true
St. Augustine, Confessions V, 6

marcel_g

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Re: The 2020 melting season
« Reply #4447 on: August 03, 2020, 03:10:53 PM »
Latest Five Day Forecast
Wind + Temp @ Surface
Large GiF!
The Great Rip-Off of 2020. Intersting to see if Arctic has any solid large ice surface after this. Probably going back into hiberna... Sorry, ....aestivation again, keeping an eye on this though.
What this melting season will prove or disprove IMHO is if a compact ice pack is more prone to melt than a dispersed pack.

Because the pack was so small and compacted, most of the energy went into the surrounding seas that had no ice left to melt, and not in pockets of water in between floes - as would happen with a more dispersed pack.

So did a more compact ice pack reflect more of the sun's energy? And is all we have left now for the remainder of the season the energy in open water that will get cooled rapidly as insolation ends and the ice edge melts?

We'll know in a few weeks I guess...

I’m not entirely sure Freegrass, the melt ponding and preconditioning of the ice all the way across the CAB, so the reduced albedo of the entire ice pack, along with the remarkably consistent clear skies under the high pressure system of July, means that a lot of solar energy went into the central pack, not just the peripheral areas.

Which means there was not only a Lot of extra top melt, but a lot of energy went into the ice, and a lot of energy went into the water under the ice. When the ice is wet or clear of snow or covered in melt ponds, apparently a lot of energy gets through into the water underneath. I would guess that open leads absorb this better, but 2020 looks like it’s been unusually conducive to absorbing solar energy. (My memory might be off, but Someone posted A few years ago about how some wavelengths go through the ice, and primarily heat the water about 5m down)

Since we don’t really know how much bottom melt is going on, and how separated the water layers stay just under the ice, we will also find out how much preconditioning and stored solar energy leads to bottom melt north of 80N as insolation disappears. And that question and your question about compactness might be hard to disentangle. If it gets windy and the ice gets moving though, I’m guessing bottom melt will dominate even in the central pack, and a lot of ice will go poof.

marcel_g

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Re: The 2020 melting season
« Reply #4448 on: August 03, 2020, 03:15:56 PM »
The growing gap ... July 23 - August 2.

Wow, this is gobsmacking. I never thought this would happen. At least until the ice was at BOE stage.

BornFromTheVoid

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Re: The 2020 melting season
« Reply #4449 on: August 03, 2020, 03:30:09 PM »
North of Greenland, change from July 24th to August 2nd.
Higher-res version on here: https://twitter.com/Icy_Samuel/status/1290278384564465667
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel