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Ice Shieldz

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Re: The 2020 melting season
« Reply #2600 on: July 12, 2020, 07:03:41 AM »
Here are the area weighted & averaged 850MB temps from 65 to 90deg north during the period of May 1st thru June 30th plotted over the last 72 years. 2020 is first place and (to a lesser degree) is first for the month of June.

Via the interface screen grabbed below, you can plot all kinds of cool variables like precipitable water and geopotential height at: https://psl.noaa.gov/cgi-bin/data/timeseries/timeseries1.pl

Sambuccu

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Re: The 2020 melting season
« Reply #2601 on: July 12, 2020, 08:42:35 AM »
Hi,

I don't think I have seen this map of ice drift recently on this topic.



johnm33

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Re: The 2020 melting season
« Reply #2602 on: July 12, 2020, 11:25:27 AM »
In Beaufort it looks like both top and bottom melt are happening, the ice has softened and spreads into any gaps. The air blowing across it is very dry enhancing evaporative cooling, so both melting and freezing are taking place keeping the sea temperature around -1.8c and air temps between +/- 2c. If any gaps open then spray freezes in the air and salt gets spread over the ice initially cooling it by about 20deg then as it 'normalises' towards 0c acts to soften the ice further. So I speculate that it's in a state of transition and could very suddenly transform.

uniquorn

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Re: The 2020 melting season
« Reply #2603 on: July 12, 2020, 11:39:34 AM »
There is a worldview animation of Beaufort, apr-jul10 here (large files)

uni-hamburg amsr2-uhh, atlantic side, jun1-jul11. click to run (6.8MB)
Bremen uses a 6.25km grid, the Hamburg grid is 3.125km. For me, the Hamburg presentation works much better with overlays.

romett1

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Re: The 2020 melting season
« Reply #2604 on: July 12, 2020, 01:51:47 PM »
3-day average 10m wind speed forecast (GFS) - wind is really picking up over Laptev.

Greenbelt

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Re: The 2020 melting season
« Reply #2605 on: July 12, 2020, 02:36:58 PM »
One impact of the persistent GAAC might be to push some of that thick ice in the Beaufort toward the soon-to-be open and warm waters of the ESS by August.  Main areas of thicker ice per HYCOM highlighted.

Pagophilus

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Re: The 2020 melting season
« Reply #2606 on: July 12, 2020, 03:56:02 PM »
But what Beaufort ice really resents is a couple of good storms to disperse all that ice and accelerate bottom melt, ice floe fragmentation and lastly meltout by bottom and lateral melt and wave washout, and the same for whatever ice remains in August in the Arctic.

Agreed. And added to this is the current clockwise rotation of the ice pack, set to continue, it seems, for one or two more weeks.  That will continue to 'pull' ice out of the Beaufort towards the Chukchi, and maybe even make the whole ice pack lean more to the Atlantic side.  It also, however, may bring new ice into the Beaufort, so perhaps the full effects in the Beaufort may not be seen for a while?
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be cause

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Re: The 2020 melting season
« Reply #2607 on: July 12, 2020, 04:06:32 PM »
 A report i haven't seen on ASIF or even being remotely suggested by recent dmi80 graph .. all time temperature record at the north Pole ..
     https://twitter.com/xavierfettweis/status/1281511326137962496/photo/1                         
 
'' The Blob warned us  Retweeted
Xavier Fettweis
@xavierfettweis
·
10 Jul
According to the NCEP-NCARv1 reanalysis, records of near-surface temperature at North-Pole (80°N-90°N) seem to have occurred on 5 and 6 July 2020 when the daily mean temperature was +4°C (Previous record +3.5°C). This must be however confirmed with the ERA5 reanalysis. ''

I recommend keeping an eye on mr Blobby's tweets (@ The Blob warned us ) ..  ;D b.c.
« Last Edit: July 12, 2020, 04:18:56 PM by be cause »
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 + 2 = 2021 
 (phew)

FishOutofWater

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Re: The 2020 melting season
« Reply #2608 on: July 12, 2020, 04:08:15 PM »
Persistence of high pressure and easterly winds along the Arctic shelf margins will lead to the melting out of the Beaufort sea ice. The warm Alaska coastal current, combined with upwelling of water with stored heat along the shelf edge will melt out the ice.

At this point storms in the Beaufort and CAA are good for the ice because they would disrupt the upwelling and transport of ice out of the Beaufort.

Pagophilus

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Re: The 2020 melting season
« Reply #2609 on: July 12, 2020, 04:16:29 PM »
Persistence of high pressure and easterly winds along the Arctic shelf margins will lead to the melting out of the Beaufort sea ice. The warm Alaska coastal current, combined with upwelling of water with stored heat along the shelf edge will melt out the ice.

At this point storms in the Beaufort and CAA are good for the ice because they would disrupt the upwelling and transport of ice out of the Beaufort.

Thank you, FOoW.   I have not integrated these factors into my thinking yet, even though a few posts ago I was urging others to think more about what is happening under the ice.  Sigh.  Much to learn.


Rough check of Beaufort buoy drift timing with worldview, apr1-jul10 4.6MB
Thanks, uniquorn.  I forget how much the Beaufort can churn.

 
On another topic, the ESS is almost completely clear in the July 12 Worldview.  As we know, it does not look pretty.  Darkening, scattered ice, melting 'streamers' at most edges, with some probable coastal algal blooms scattered around.   Image unaltered.
« Last Edit: July 12, 2020, 05:41:37 PM by Pagophilus »
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uniquorn

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Re: The 2020 melting season
« Reply #2610 on: July 12, 2020, 05:07:34 PM »
Data from simb386840 in the Beaufort has been sporadic recently but there was an update today.
Ocean temperature just beneath the ice has risen again to -1.39

More details here

Pagophilus

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Re: The 2020 melting season
« Reply #2611 on: July 12, 2020, 06:44:11 PM »
3-day average 10m wind speed forecast (GFS) - wind is really picking up over Laptev.

And here is what that looks like on Worldview.  The ice edge at the top left of the image, that faces top or top left, is being compacted by the wind.  In the center of the image, streamers and ragged floes being distributed by the wind on ice edges that face towards bottom right.  And on the ice pack edge at the bottom right of the image, melting streamers are being bent right and being flattened towards the icepack.  The whole ice edge is like a giant weathervane...
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gandul

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Re: The 2020 melting season
« Reply #2612 on: July 12, 2020, 07:15:16 PM »
Persistence of high pressure and easterly winds along the Arctic shelf margins will lead to the melting out of the Beaufort sea ice. The warm Alaska coastal current, combined with upwelling of water with stored heat along the shelf edge will melt out the ice.

At this point storms in the Beaufort and CAA are good for the ice because they would disrupt the upwelling and transport of ice out of the Beaufort.
At this point, but not in August.
Also I wouldn't be so sure if Beaufort meltout at this point, without the help of strong meteorological events in one direction or another. The melting there looks pretty anemic to me so far even when it starts to show weaknesses ( because of a storm it passed by). But a moderate/strong late summer storm could eventually wipe out the sea ice.

<Removed personal part. O>
« Last Edit: July 12, 2020, 07:28:25 PM by oren »

gandul

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Re: The 2020 melting season
« Reply #2613 on: July 12, 2020, 07:19:36 PM »
Persistence of high pressure and easterly winds along the Arctic shelf margins will lead to the melting out of the Beaufort sea ice. The warm Alaska coastal current, combined with upwelling of water with stored heat along the shelf edge will melt out the ice.

At this point storms in the Beaufort and CAA are good for the ice because they would disrupt the upwelling and transport of ice out of the Beaufort.

Thank you, FOoW.   I have not integrated these factors into my thinking yet, even though a few posts ago I was urging others to think more about what is happening under the ice.  Sigh.  Much to learn.


Rough check of Beaufort buoy drift timing with worldview, apr1-jul10 4.6MB
Thanks, uniquorn.  I forget how much the Beaufort can churn.

 
On another topic, the ESS is almost completely clear in the July 12 Worldview.  As we know, it does not look pretty.  Darkening, scattered ice, melting 'streamers' at most edges, with some probable coastal algal blooms scattered around.   Image unaltered.
Careful with this post, I would add a 'remind me in one month'
« Last Edit: July 12, 2020, 07:29:16 PM by oren »

Pagophilus

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Re: The 2020 melting season
« Reply #2614 on: July 12, 2020, 07:39:11 PM »
Careful with this post, I would add a 'remind me in one month'

Uh-oh, what part should I be careful about?  Several subjects on the post...
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oren

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Re: The 2020 melting season
« Reply #2615 on: July 12, 2020, 09:04:32 PM »
Sorry, I did a bit of an edit there. Gandul meant the part where Foow predicted the meltout of the Beaufort.

Csnavywx

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Re: The 2020 melting season
« Reply #2616 on: July 12, 2020, 09:42:59 PM »
Looks like the melt-pond drainage phase is about over in the CAB and area will start decreasing steadily again. Area losses should start gradually accelerating should this blocking event continue to hold and thickness drops start taking their toll and increasing the in-situ open water fraction. Also, the open water front (especially from the Laptev) looks to advance bodily into the CAB soon, which will hasten the retreat.

GoSouthYoungins

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Re: The 2020 melting season
« Reply #2617 on: July 12, 2020, 09:52:45 PM »
As the GAAC insolation melts the CAB ice pack, the GAAC compacting forces will get find less resistance. Thus, if the GAAC continues for another month, there will be a large ice ball at the north pole for Santa to sit on (and no other ice).
big time oops

uniquorn

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Re: The 2020 melting season
« Reply #2618 on: July 12, 2020, 10:25:07 PM »
We have become used to thick MYI from the CAA drifting into the Beaufort. Here using NSIDC, EASE-Grid Sea Ice Age, jan2000-jun2020 to illustrate the age and structural integrity of the ice north of CAA this year.
The weather has been more favourable to the Beaufort than some other seas, hopefully it will hold out.
Full arctic animation, jan2000-jun2020 here

Rod

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Re: The 2020 melting season
« Reply #2619 on: July 12, 2020, 10:39:36 PM »
I usually only look three days out for forecasts in the Arctic  Anything beyond that must be taken with a large grain of salt. 

The high pressure system in the CAB for the last few model runs seems to be weakening in the short term.

Interestingly, the low that Bbr predicted a few days ago would come up through the Beaufort now looks a little bit more likely on the GFS 3 day average.

I will leave it to the experts to provide the longer day forecasts, but if this high (which the professional meteorologists are already saying might be a record in the satellite era) gets followed by a strong low pressure system that will churn up the ice in the Beaufort and then move over the CAB,  look out!

The Beaufort is the only area where the ice is still holding up strong relative to recent years.

Edit: as has been pointed out by uniquorn and by ossifrage, this ice is not healthy. It is just showing increased extent data right now. But, that could change fast!

James Bond likes his martinis shaken not stirred. Looks like this year we might get to try it both ways in the Arctic - first stirred then shaken.
« Last Edit: July 13, 2020, 12:14:39 AM by Rod »

Ossifrage

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Re: The 2020 melting season
« Reply #2620 on: July 12, 2020, 11:22:36 PM »
I'm sorry I haven't taken the time to circle back here and engage further lately.

But I'm glad to see some attention being paid to the state of the CAA, because the state of the CAA is not good. The strength of the CAA garlic press has always been the large, contiguous reserves of multiyear ice sheltered in the northern seas and channels or along the CAA/CAB frontier. Last year's crack exposed the core of those reserves to increased open-water albedo and to mechanical fracturing aided by the shearing force of the clockwise pack rotation.

The CAA, in part, had a pretty good winter. But one winter doesn't fix the damage; formerly contiguous MYI is now cobblestones of older (but potentially weakened) ice embedded in a FYI matrix. That's more vulnerable to traditional melt, and perhaps more vulnerable to mechanical pack deformation if we see another full-scale Crack again this year. Which seems increasingly plausible.

Meanwhile, the adjacent Beaufort looks to be in good shape, but it is benefiting in no small part to clockwise-exported MYI from the Crack. Lord M Vader posted a volume anomaly map a couple pages back that demonstrates the high positive anomaly at the western edge of the CAA/CAB boundary and into the Beaufort. The bulk of the Beaufort itself doesn't show markedly high anomalies, but to some extent that is merely because the imported MYI is buffering the region against what might otherwise have been more dramatic melt.

None of that means the Beaufort is in good shape. There's no viable mechanism to ship that ice back east to where it belongs. Whether now or in future, it will melt out. If we see further Crack export from the CAA, the Beaufort may even end the season with quite a bit of ice remaining, but counting that ice as a sign of health for the region is like counting post-apocalypse zombies as part of the "population".

gandul

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Re: The 2020 melting season
« Reply #2621 on: July 12, 2020, 11:23:48 PM »
I don't see in the forecast storm strong enough to do real damage, yet. But rest assured that the effect of a <980hPa can be swift and very dramatic. A 50 km block can be broken into a range of few km to smaller than 1 km blocks in a matter of three days, and in another 3 days down to hundred meter floes. There's obvious enhancement of bottom & lateral melt, and partial sinking and even flipping upside down of smaller floes accelerates melting too. The upwelling and warming of coastal water is only effective on melting ice if the floes are broken and dispersed into these warmer waters. Otherwise the effect is very slow or null. I find the effect of moderate storms (not even GAC) quite spectacular.

And for the record, the disastrous fall and winter of 2016 was mostly caused by a great heat transfer enabled by storm after storm mechanically destroying the ice over a vast line from Laptev to Beaufort, from June to end of August. The usual ridge-seekers could not even understand.
« Last Edit: July 12, 2020, 11:29:21 PM by gandul »

Rod

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Re: The 2020 melting season
« Reply #2622 on: July 12, 2020, 11:56:28 PM »

but counting that ice as a sign of health for the region is like counting post-apocalypse zombies as part of the "population".

I was proud of my James Bond reference to stirred and shaken, but this is pure poetry for the 2020 melt season.

Thank you as always for your valuable contributions Ossifrage!

Burnrate

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Re: The 2020 melting season
« Reply #2623 on: July 13, 2020, 02:01:58 AM »
Considering how the reduction in aerosols from the pandemic is influencing the ice melt I wonder if the reduction in sulfur dioxide from shipping is also having a major effect.  Perhaps these two things starting at about the same time are creating a much bigger effect than was anticipated.

http://www.imo.org/en/MediaCentre/HotTopics/Pages/Sulphur-2020.aspx
On January 1st of this year all shipping was required to use low sulfur fuel.  It says the annual reduction is expected to be 8.5 million tons.

If I'm reading everything right that would be a reduction of about 10% of the worlds sulfur dioxide output. (https://ourworldindata.org/grapher/so-emissions-by-world-region-in-million-tonnes)

So much extra heat pouring in.

Freegrass

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Re: The 2020 melting season
« Reply #2624 on: July 13, 2020, 02:24:48 AM »
Latest Five Day Forecast
Wind @ Surface + Total Cloud Water
Wind + Temp @ Surface

Large GiFS!
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FishOutofWater

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Re: The 2020 melting season
« Reply #2625 on: July 13, 2020, 03:01:16 AM »
Grandul, take a look at Freegrass' wind and temperature animation. During this episode of strong and persistent high pressure there are many  variations in wind direction and speed near the shelf breaks. This variability is bringing ice imported into the Beaufort sea into close contact with warm water from the Mackenzie River and water upwelled along the shelf break. Of course, there are going to be storms over the Arctic ocean in late summer so we will get to see the impact of storms on ice and the September minimum.

In the summer of 2014 there was a storm over the Canadian side of the Arctic ocean that hit in mid to late July, cooling the temperature and stalling the melting season. It ended up being a pretty good summer for ice because of the cooling and the reduction of overall ice transport that the storm brought on. The worst summers for ice such as 2007 and 2012 have had persistent ice transport. Recovery summers have typically had variable winds and no persistent high or low pressure patterns.

oren

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Re: The 2020 melting season
« Reply #2626 on: July 13, 2020, 03:34:26 AM »
For those interested in the CAA and breakup of the fast ice in the channels, I strongly recommend watching the animation in the linked post from the RAMBB thread, showing a high time resolution of the effect of tides and local currents on the ice.
https://forum.arctic-sea-ice.net/index.php/topic,2649.msg273199.html#msg273199

p.s. Welcome back Ossifrage, a pleasure reading your posts again.The PGAS awaits...

Freegrass

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Re: The 2020 melting season
« Reply #2627 on: July 13, 2020, 03:46:28 AM »
The Bering Strait Current (BSC) is pretty strong right now, and seems to be penetrating deep into the ice. I warned this could happen at the start of the season, and now it is showing its ugly face...

There have been a few science papers posted already that show an increase in the speed of the BSC. If the cause is a slowdown of the AMOC, that has yet to be determined, but no matter what the cause is, the BSC is a thing to watch IMHO. Especially this year, because this year there is no arm of thick ice in the Chukchi to protect the CAB from that inflow of hot pacific water.

And so it shows...

More so IMHO because hot pacific water has been flowing under the ice all year long, IMO weakening the ice before the melting season even began. Now we just have to wait and see how far that hot pacific water will penetrate into the CAB.

I really think that a warming and speedy BSC will become a big problem for the Arctic. I'm still dying to hear more about this from the specialists. I can't believe nobody is debating this...  :'(
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oren

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Re: The 2020 melting season
« Reply #2628 on: July 13, 2020, 03:49:28 AM »
How can you tell the difference on a satellite photo between a ice covered in melt ponds and frozen ice that isn't covered by snow?  Both would appear blue from a distance and I don't think most satellite photos have the resolution to show the difference.  Is there something I'm missing?
Here's a natural color Worldview pic from June 26 (much bluer in most areas) vs. the same area from today July 10.  That ice didn't refreeze, it just has less standing water on it is my interpretation. The bluish tint seems to fade to grayish as the melt pond drain I think.

This doesn't address my question.  How do you know that the blue on the June 26 photo is from melt ponds, not ice?  Ice appears blue from a distance.
Continuing the discussion on bluish tinge, melt ponds and Worldview, here is a very interesting image posted recently on the Mosaic thread, along with a Worldview image from the same date.
The source of bluish tinge can be seen, as the melt ponds are light blue and often cover significant areas (perhaps the open water leads between the fractured floes contribute to the effect?). It is interesting that on Worldview the area appeared as grayish, not really bluish, leading to the conclusion that very bluish images contain even more melt ponds, perhaps much more.

Edit: To see the Mosaic image in its full glory: right-click, open in new tab, zoom.




Phoenix

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Re: The 2020 melting season
« Reply #2629 on: July 13, 2020, 04:30:41 AM »
The potential in the Arctic at this time of year under ice free conditions is 450-500 W/m2 per day.

According to Nico Sun, the CAB runs at about 20% of potential solar input at this time of year, so in a typical early July day, it's receiving about 100 W / m2.

https://cryospherecomputing.tk/awp-region.html

Does heat matter? I think so. You indicate tens of W / m2. That would be less than insolation, but still material.
You are bluffing your way through this argument, and badly. You cannot quote Nico Sun without understanding what it is he is really calculating. I have now gone and refreshed my failing memory, and it turns out he is assuming an albedo of 80% for ice and snow, and 85% for ice and snow in the High Arctic. For open water he is assuming 0% albedo. This is why he is showing ~20%-25% of potential solar input for the CAB: 15% of the CAB sea ice area, plus 100% of the (total CAB surface minus CAB sea ice area). However we are currently in a situation where the CAB is made up of gray ice full of extensive melt ponds and hardly any snow, with an albedo which is probably 50%-60% and certainly not 85%. So in a typical July day it is probably receiving double your number at about 200 W/m2.
In addition, his assumption is that the weather (cloudy/sunny), which he ignores, averages out. However a stuck weather pattern generating clear skies over the CAB in early July does not necessarily average out and thus the generated anomaly is not necessarily comparable.
I would of course appreciate input from those who can estimate these numbers better, this is just a back of the envelope exercise.

I was right and you were wrong, but you were free to accuse me of bad intention here. You and Friv win. This is your fief and reality is whatever you want it to be. How someone spends seven years studying this shit and doesn't know what the correct albedo is a true wonder. Where did you come up with these numbers? Good luck Oren.

<Nah. You were not right and I was not wrong, though the numbers are admittedly debatable. Feel free to debate them, just leave the huffing and puffing aside. O>
« Last Edit: July 13, 2020, 04:58:47 AM by oren »

Rod

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Re: The 2020 melting season
« Reply #2630 on: July 13, 2020, 04:33:46 AM »
I just want everyone to know what a bad ass FOW is. He was fighting for you before many of you were born! Most people on this forum are old guys, but some are not. Never forget the old guys who fight for you. (I say this because I’m am one of them 😂)

I cross post this from another thread because I think it is important.

I, too, am frustrated, Rod with the level of communication of climate science research to the public. My research career cannot be described as brilliant but I learned a lot about the politics of science. I developed nuclear waste safety research programs and managed them with national labs and universities. I approved and oversaw research grants with universities. When Newt Gingrich & the GOP took over congress in 1994 all of our nuclear waste safety research was closed down.

Perhaps EU scientists don't have to deal with such crazy political wind shifts as U.S. scientists, but there are systemic reasons why scientists are not engaging very well with the public.

Pagophilus

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Re: The 2020 melting season
« Reply #2631 on: July 13, 2020, 04:37:29 AM »
It really is eye-opening for me to see a surface (or near surface image) paired with a Worldview image like this.  Thank you. Somehow I had imagined from just looking at Worldview that the ice nearer the pole would be a whole lot more solid and white and frosty than this, with occasional meltponds on top and some occasional breaks in the ice.  The reality conveyed in this photograph was surprising to me, where I can see how very wet and fractured and melt-ponded the ice really is.  I knew the situation was a fragile one, but it seems much more so now. 


Continuing the discussion on bluish tinge, melt ponds and Worldview, here is a very interesting image posted recently on the Mosaic thread, along with a Worldview image from the same date.
The source of bluish tinge can be seen, as the melt ponds are light blue and often cover significant areas (perhaps the open water leads between the fractured floes contribute to the effect?). It is interesting that on Worldview the area appeared as grayish, not really bluish, leading to the conclusion that very bluish images contain even more melt ponds, perhaps much more.

« Last Edit: July 13, 2020, 04:46:57 AM by Pagophilus »
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VeliAlbertKallio

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Re: The 2020 melting season
« Reply #2632 on: July 13, 2020, 05:09:03 AM »
Earlier in the thread someone notified brownish tints becoming common in sea ice this year suggesting strong algae growth. The large amount of sunlight available in 2020 to algae to photosynthesise might change properties of water beneath sea ice by turning it murkier and opaque. This would then trap more sunlight and heat right beneath sea ice and thus accelerate its melting (even though not always visible from the surface covered by sea ice). As sea ice gets thinner (sic.) the light contribution is for increased algae photosynthesis and its contribution as a positive feedback in ice melting is likely to grow. One area for someone to pick up for a good PhD thesis that would contribute much to modelling, also a rare piece that could be studied in a laboratory setting at first to test the concept of alga-driven melt feedback.  8)
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Aluminium

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Re: The 2020 melting season
« Reply #2633 on: July 13, 2020, 06:44:03 AM »
July 8-12.

2019.

ArcTickTock

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Re: The 2020 melting season
« Reply #2634 on: July 13, 2020, 07:23:36 AM »
There is a worldview animation of Beaufort, apr-jul10 here (large files)

uni-hamburg amsr2-uhh, atlantic side, jun1-jul11. click to run (6.8MB)
Bremen uses a 6.25km grid, the Hamburg grid is 3.125km. For me, the Hamburg presentation works much better with overlays.

Oh my word!!!  I am used to Atlantic waters ploughing their way through the Barents Sea ice halfway between Novaya Zemlya and FJL.  Then hooking north and scouring the ice out of the channel just east of FJL and west of the Kara Shelf only to stop just north of FJL where it drops into the Nansen and goes under the Arctic Surface Water and becomes separated from the ice.  But the last few days melt across the Atlantic Front from Svalbard to Severnaya Zemlya looks to be more than insolation can do alone.  That looks like Atlantic water attacking the entire front right up to the Nansen ( or even past ) to me!

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Re: The 2020 melting season
« Reply #2635 on: July 13, 2020, 07:42:46 AM »
Looks like the ESS is going to be losing a lot of ice in the next week.  In the CAA I am watching two areas closely.  They are minor but in my opinion harbingers.  I may be under a misapprehension but it seems to me that though the sea ice at either end of Jones Sound and the Wellington Channel melts early each season, the ice in the middle of the sound and channel is very tough to melt out until late if at all.  This year these waterways look vulnerable to me??

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Re: The 2020 melting season
« Reply #2636 on: July 13, 2020, 07:58:33 AM »
The Bering Strait Current (BSC) is pretty strong right now, and seems to be penetrating deep into the ice. I warned this could happen at the start of the season, and now it is showing its ugly face...

There have been a few science papers posted already that show an increase in the speed of the BSC. If the cause is a slowdown of the AMOC, that has yet to be determined, but no matter what the cause is, the BSC is a thing to watch IMHO. Especially this year, because this year there is no arm of thick ice in the Chukchi to protect the CAB from that inflow of hot pacific water.

And so it shows...

More so IMHO because hot pacific water has been flowing under the ice all year long, IMO weakening the ice before the melting season even began. Now we just have to wait and see how far that hot pacific water will penetrate into the CAB.

I really think that a warming and speedy BSC will become a big problem for the Arctic. I'm still dying to hear more about this from the specialists. I can't believe nobody is debating this...  :'(

Great post.  Am I correct that BSC is 10% of Atlantic Water entering the Arctic.  That being said it is I believe much less saline than AW and if the Pacific is slightly elevated versus the Arctic, relentless in its inflow.  A big danger here is that it may be able to mix more readily with Arctic Surface Water than AW particularly if there is a disturbance like a GAC.  The Beaufort is very fresh ( probably why it is holding out so well in recent years ) but I am not so sure the Chukchi path into the
CAB is as well protected by low salinity, maybe somebody has data on this?
« Last Edit: July 13, 2020, 08:04:53 AM by ArcTickTock »

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Re: The 2020 melting season
« Reply #2637 on: July 13, 2020, 08:19:21 AM »
July 8-12.

2019.

It is impressive how a protruding Laptev "bite" is not stretching towards the 80N line like most years, but instead the whole width of the Laptev sea reached 80N at the same time

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Re: The 2020 melting season
« Reply #2638 on: July 13, 2020, 08:19:46 AM »
Folks please focus on things relevant for the current melting season. Longer term trends and science should go in dedicated threads where someone can still dig them a couple of years from now.
Is there a pertinent indication the BSC is stronger this year than it was in the past few years? If so, discuss away, else defer to the BSC thread.

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Re: The 2020 melting season
« Reply #2639 on: July 13, 2020, 08:27:19 AM »
July 8-12.

2019.

It is impressive how a protruding Laptev "bite" is not stretching towards the 80N line like most years, but instead the whole width of the Laptev sea reached 80N at the same time

Exactly.

In fact ice edge on the whole Eastern half of the Arctic, from Svalbard to Wrangel Island, is withdrawing simultaneously.

Meanwhile worldview shows us telltale signs of melt.

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Re: The 2020 melting season
« Reply #2640 on: July 13, 2020, 08:56:58 AM »
Grandul, take a look at Freegrass' wind and temperature animation. During this episode of strong and persistent high pressure there are many  variations in wind direction and speed near the shelf breaks....

In the summer of 2014 there was a storm over the Canadian side of the Arctic ocean that hit in mid to late July, cooling the temperature and stalling the melting season. It ended up being a pretty good summer for ice because of the cooling and the reduction of overall ice transport that the storm brought on. The worst summers for ice such as 2007 and 2012 have had persistent ice transport. Recovery summers have typically had variable winds and no persistent high or low pressure patterns.
Of course a persistent low in the right location cools down the atmosphere and may set up the right circulation for ice retention. Last year ~20 of July was another example.
But I was not talking about that kind of setup. Anyway.

This year persistent high undoubtedly has induced melting Arctic wide.
However its persistence is setting compaction in the vicinity of record highs. Compaction also slows down real melt for a number of reasons. No open water between floes except periphery, not much mixing under the central pack (downwelling, actually), and yes, plenty of sun and meltponding and draining, but as the high goes on there static losing power there is also a cooling of temperatures and no WAAs
That's why I think storms in August are the real possibility to end up with this wreck of ice.

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Re: The 2020 melting season
« Reply #2641 on: July 13, 2020, 10:52:14 AM »
Folks please focus on things relevant for the current melting season. Longer term trends and science should go in dedicated threads where someone can still dig them a couple of years from now.
Is there a pertinent indication the BSC is stronger this year than it was in the past few years? If so, discuss away, else defer to the BSC thread.
I think the BSC is very relevant for the current melting season Oren. Just look at how much it is already penetrating the ice. More so than any other year at first glance on Worldview. So I think it is very relevant.

The debate on the long term trend of the BSC must indeed be discussed in the Bering Strait thread.
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Re: The 2020 melting season
« Reply #2642 on: July 13, 2020, 11:10:23 AM »
https://twitter.com/AlaskaWx/status/1282347875121258501

Quote
Dramatic decrease this week in Chukchi Sea #seaice extent in @NSIDC  data with the largest decreases on the Chukotka side. Beaufort Sea ice melt remains slow and extent is above 1981-2010 average, though ice is gradually clearing from the the coast.


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Re: The 2020 melting season
« Reply #2643 on: July 13, 2020, 12:07:08 PM »
...  But the last few days melt across the Atlantic Front from Svalbard to Severnaya Zemlya looks to be more than insolation can do alone.  That looks like Atlantic water attacking the entire front right up to the Nansen ( or even past ) to me!

Remember to also consider the effects of the wind pushing the ice front. It has been pushing it in a somewhat westerly direction and also somewhat north -- see reply #2601 above and its figure, posted by Sambuccu.



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Re: The 2020 melting season
« Reply #2644 on: July 13, 2020, 12:15:03 PM »
Either the NE passage is open on the Siberian side, or it is hanging on by a thread along the coast near SZ.  The area over SZ is cloudy this morning...
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Re: The 2020 melting season
« Reply #2645 on: July 13, 2020, 12:22:58 PM »
Last week in data (the SAR Fram export movie follows later today)

Click to play.

blumenkraft

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Re: The 2020 melting season
« Reply #2646 on: July 13, 2020, 12:32:05 PM »
...  But the last few days melt across the Atlantic Front from Svalbard to Severnaya Zemlya looks to be more than insolation can do alone.  That looks like Atlantic water attacking the entire front right up to the Nansen ( or even past ) to me!

Remember to also consider the effects of the wind pushing the ice front. It has been pushing it in a somewhat westerly direction and also somewhat north -- see reply #2601 above and its figure, posted by Sambuccu.

I think you are both right!

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Re: The 2020 melting season
« Reply #2647 on: July 13, 2020, 12:34:09 PM »
And here is the whole picture SST wise. Click to play.
« Last Edit: July 13, 2020, 02:24:19 PM by blumenkraft »

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Re: The 2020 melting season
« Reply #2648 on: July 13, 2020, 02:15:20 PM »
There is a worldview animation of Beaufort, apr-jul10 here (large files)

uni-hamburg amsr2-uhh, atlantic side, jun1-jul11. click to run (6.8MB)
Bremen uses a 6.25km grid, the Hamburg grid is 3.125km. For me, the Hamburg presentation works much better with overlays.

Oh my word!!!  I am used to Atlantic waters ploughing their way through the Barents Sea ice halfway between Novaya Zemlya and FJL.  Then hooking north and scouring the ice out of the channel just east of FJL and west of the Kara Shelf only to stop just north of FJL where it drops into the Nansen and goes under the Arctic Surface Water and becomes separated from the ice.  But the last few days melt across the Atlantic Front from Svalbard to Severnaya Zemlya looks to be more than insolation can do alone.  That looks like Atlantic water attacking the entire front right up to the Nansen ( or even past ) to me!

I think this is what I was trying to point out on July 9, message # 2477, but probably less coherently than you have ... the image  posted then is below.

Some thoughts, not based on experience:  Current weather has the Arctic ice cap rotating clockwise towards this bathymetric line (where the Arctic seafloor suddenly plunges downwards, and warm, saline Atlantic waters disappear into the depths). 

If this has been established as the July/August ice's Atlantic boundary (as it often is), then that means the ice cap will continue to rotate towards this line and the ice will get melted out by the warm Atlantic waters beyond this point. 

It might look as if nothing is happening here under these conditions, but in fact a lot of ice will be lost.  This ice melting might seem to be occurring in some other Arctic seas, but the ice will be just being rotated to the toasty Atlantic front and vanishing there.  (Admittedly, compaction might be taking the ice edge in this area towards the pole right now, rather than melting).

First image is for July 8 position, second for July 12.  Red line approximately marks the 200m submarine contour
« Last Edit: July 13, 2020, 02:54:02 PM by Pagophilus »
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Re: The 2020 melting season
« Reply #2649 on: July 13, 2020, 02:43:06 PM »

- Extent loss on this day 79k, 24 k less than the average loss on this day (of the last 10 years) of 103k,


Extent losses may be slowing, probably because much of the low hanging compaction fruit has already been picked.  So although insolation continues to be brutal, at least much of the ice is packed together, thereby slowing its melting from underneath and the sides somewhat.
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