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uniquorn

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Re: The 2020 melting season
« Reply #5600 on: August 31, 2020, 04:29:52 PM »
A look back at the development of low concentration ice north of greenland, jun17-aug30 (amsr2-uhh sic)
I think I've finally figured out the gap north of Greenland. On your graphic you can clearly see how the GAAC moves the ice westwards. But on the east side of Greenland the ice bumps into Greenland and a strong current out of Fram. This causes the ice to rip apart, get stretched and weakend. This weak ice then melted out because of warm and powerful winds coming through Fram.

I think that's the story of the 2020 Greenland Gap.
More likely to be due to the ocean bumping into Greenland (and the shelves to the north) in my opinion.

UCMiami

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Re: The 2020 melting season
« Reply #5601 on: August 31, 2020, 04:41:47 PM »
A look back at the development of low concentration ice north of greenland, jun17-aug30 (amsr2-uhh sic)
Fascinating - looking at the eastern coast of Greenland there appears to be a constant coastal flow north that creates 3/4 of a whirlpool action - ice flows move north then east as they reach the top of Greenland and then get pulled south into the general Fram export. This motion continues through the whole time frame of the GIF often at greater speeds than other ice in this picture.

In response to no storms this season comments:
While the season didn't have prolonged storms, the longevity of an almost arctic wide anticyclone from well before peak isolation and weeks after that peak is unique to this year and suggests there is 'more than one way to skin a cat.' And the post peak weather while not strong, kept importing heat from the south. The GAC of 2012 struck a very different arctic with much greater ice integrity; this modern arctic doesn't need as much energy input to move the ice around.

Final comment - a surprise to me has been the lack of Nares export even though the channel has been clear all summer. That has spread also to the rest of the CAA - to date very little ice from the CAB has been pushed into those channels - the flow has all been into the Beaufort replenishing that sea ice and making it the laggard. With current weather forecasts, that may be about to change, but there is still a lot of wind forecast to blow across the openings and not down them.

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Re: The 2020 melting season
« Reply #5602 on: August 31, 2020, 04:48:39 PM »
HYCOM 7 day prediction. Whole pack is sliding towards Beaufort. Leaving CAA almost empty.  :o

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Re: The 2020 melting season
« Reply #5603 on: August 31, 2020, 05:08:39 PM »
Whole pack is sliding towards Beaufort.
Laura can put that ice on a freeway to the beaufort and maybe help us to put 2020 in the record books?

It'll be a interesting week for the Arctic with Laura coming...


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Re: The 2020 melting season
« Reply #5604 on: August 31, 2020, 05:55:46 PM »
NSIDC is also seeing the collapse of the Beaufort Sea ice bagel. The Laptev Sea is even closer to the absolute record of 2014 - 1029.22 km2.

Freegrass

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Re: The 2020 melting season
« Reply #5605 on: August 31, 2020, 06:01:29 PM »
A look back at the development of low concentration ice north of greenland, jun17-aug30 (amsr2-uhh sic)
I think I've finally figured out the gap north of Greenland. On your graphic you can clearly see how the GAAC moves the ice westwards. But on the east side of Greenland the ice bumps into Greenland and a strong current out of Fram. This causes the ice to rip apart, get stretched and weakend. This weak ice then melted out because of warm and powerful winds coming through Fram.

I think that's the story of the 2020 Greenland Gap.
More likely to be due to the ocean bumping into Greenland (and the shelves to the north) in my opinion.
Are you talking about the transpolar drift flushing the ice through Fram while the GAAC was blowing the ice to the west?

I'll leave it up to you guys to explain it correctly.
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Re: The 2020 melting season
« Reply #5606 on: August 31, 2020, 06:31:14 PM »
Latest projection... all of the previous 20 years are now going for the 2nd lowest again.
To equal 2012, losses would need to average 54,100 km² per day from now until September 16th (2012 minimum date). The previous record large loss for this period was 27,900 km² per day in 2010.
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

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Re: The 2020 melting season
« Reply #5607 on: August 31, 2020, 07:01:02 PM »
Latest projection... all of the previous 20 years are now going for the 2nd lowest again.
To equal 2012, losses would need to average 54,100 km² per day from now until September 16th (2012 minimum date). The previous record large loss for this period was 27,900 km² per day in 2010.
My hunch right now is, that we'll see a late minimum - at or after the equinox.

The combination of fragmented ice, vastly increased solar capture earlier in the season, bottom melt, vulnerable extent south of 80N and upcoming potential for rough weather leads me in this direction.  This would also be in keeping with the "extension" (earlier start, later end) of the melt seasons we've been seeing progressively for possibly as long as a decade or more.

While there's still a chance we could make it to 2012, I think it will end up a 'near miss'.

The difference between the two (2020/2012) may more semantic than concrete, considering the overall current ice quality.

It will be interesting to see how close my assessment is to reality.

And to echo Neven - it's all about the melting momentum now.
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Re: The 2020 melting season
« Reply #5608 on: August 31, 2020, 07:09:34 PM »
Would a 2012-tier deviation from the trend of 2019/2020 result in a near BOE, or would there still be more room to fall? To phrase it differently, as 2020 appears to be progressing towards an in-trend approach (either this year or within the next few) to 2012 extent and area, has the risk of an outlier year causing even more extreme disruption increased?

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Re: The 2020 melting season
« Reply #5609 on: August 31, 2020, 07:24:46 PM »
Would a 2012-tier deviation from the trend of 2019/2020 result in a near BOE, or would there still be more room to fall? To phrase it differently, as 2020 appears to be progressing towards an in-trend approach (either this year or within the next few) to 2012 extent and area, has the risk of an outlier year causing even more extreme disruption increased?

To answer in very simplistic terms: 2012 saw a 1 million km2 drop from the year before (2011).  Assuming we see something in the range of 3.5 to 3.9 million km2 at the lowest point in 2020, *if* there was a similar 1 million km2 drop in 2021, we'd see something like 2.5 to 2.9 million km2.  Not yet threatening a BOE (defined as less than 1 million km2), but getting closer.

I may well be corrected by other people with more in depth analyses of your question, however.

uniquorn

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Re: The 2020 melting season
« Reply #5610 on: August 31, 2020, 08:02:48 PM »
whoi itp114 in the Beaufort. Microcat1 is mounted at 5m depth. Peaked at -0.665C today, avg closer to -0.75. Position is roughly centre of the worldview image.

Last buoy status on 2020/8/31 113047 UTC : temperature = -0.8125 °C, battery = 10.423 V
Plot of ITP Buoy Status
Last position on 2020/8/31 113047 UTC : 74.6377° N, 136.6473° W

2020  244.20834   -0.7900   26.4626   5.963
2020  244.21876   -0.7863   26.4580   5.967
2020  244.22918   -0.7592   26.4432   5.968
2020  244.23959   -0.6650   26.4070   5.963
2020  244.25001   -0.7083   26.4379   5.964
2020  244.26043   -0.7417   26.4465   5.962
2020  244.27084   -0.7502   26.4250   5.960
2020  244.28126   -0.7843   26.4523   5.956
2020  244.29168   -0.8026   26.4560   5.962

https://go.nasa.gov/2QC7gCW
https://www.whoi.edu/page.do?pid=165196

Freegrass

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Re: The 2020 melting season
« Reply #5611 on: August 31, 2020, 08:53:38 PM »
Latest Five Day Forecast
Wind @ Surface + Total Precipitable Water
Large GiF!
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uniquorn

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Re: The 2020 melting season
« Reply #5612 on: August 31, 2020, 10:01:27 PM »
following up on whoi itp114, here is the recent drift path.

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Re: The 2020 melting season
« Reply #5613 on: August 31, 2020, 10:11:45 PM »
whoi itp114 in the Beaufort. Microcat1 is mounted at 5m depth. Peaked at -0.665C today, avg closer to -0.75. Position is roughly centre of the worldview image.

Last buoy status on 2020/8/31 113047 UTC : temperature = -0.8125 °C, battery = 10.423 V
Plot of ITP Buoy Status
Last position on 2020/8/31 113047 UTC : 74.6377° N, 136.6473° W

2020  244.20834   -0.7900   26.4626   5.963
2020  244.21876   -0.7863   26.4580   5.967
2020  244.22918   -0.7592   26.4432   5.968
2020  244.23959   -0.6650   26.4070   5.963
2020  244.25001   -0.7083   26.4379   5.964
2020  244.26043   -0.7417   26.4465   5.962
2020  244.27084   -0.7502   26.4250   5.960
2020  244.28126   -0.7843   26.4523   5.956
2020  244.29168   -0.8026   26.4560   5.962

https://go.nasa.gov/2QC7gCW
https://www.whoi.edu/page.do?pid=165196

Still seeing bottom melt.  That could easily be 1-1.5C a day pending on how well mixed the top 5-10M of water are.
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Re: The 2020 melting season
« Reply #5614 on: August 31, 2020, 10:12:07 PM »
This is a weird breakup. Can this be because of wave action?

To make a proper assessment one needs to know where it is so we can compare location with wind and wave action now and a short time ago.
« Last Edit: August 31, 2020, 10:26:52 PM by igs »

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Re: The 2020 melting season
« Reply #5615 on: August 31, 2020, 10:20:16 PM »
Today the Ice Bagel in the Beaufort Sea is broken for the first time in Danish data.

http://ocean.dmi.dk/arctic/icedrift_anim/index.php


Indeed, just wanted to say the same and who is comparing development in the BF-Sea can see that most of it is there to go. not much will be left anyway and with the right weather, who knows.

uniquorn

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Re: The 2020 melting season
« Reply #5616 on: August 31, 2020, 10:22:12 PM »
A look back at the development of low concentration ice north of greenland, jun17-aug30 (amsr2-uhh sic)
I think I've finally figured out the gap north of Greenland. On your graphic you can clearly see how the GAAC moves the ice westwards. But on the east side of Greenland the ice bumps into Greenland and a strong current out of Fram. This causes the ice to rip apart, get stretched and weakend. This weak ice then melted out because of warm and powerful winds coming through Fram.

I think that's the story of the 2020 Greenland Gap.
More likely to be due to the ocean bumping into Greenland (and the shelves to the north) in my opinion.
Are you talking about the transpolar drift flushing the ice through Fram while the GAAC was blowing the ice to the west?

I'll leave it up to you guys to explain it correctly.
my bold in the second quote.
If you meant a strong current into the Fram then we are thinking along the same lines. Southerly winds played a big part then the thin ice has less damping effect on ocean turbulence at the shelf breaks which likely allows more mixing of returning atl water.

glennbuck

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Re: The 2020 melting season
« Reply #5617 on: August 31, 2020, 10:58:10 PM »
Latest projection... all of the previous 20 years are now going for the 2nd lowest again.
To equal 2012, losses would need to average 54,100 km² per day from now until September 16th (2012 minimum date). The previous record large loss for this period was 27,900 km² per day in 2010.
My hunch right now is, that we'll see a late minimum - at or after the equinox.

The combination of fragmented ice, vastly increased solar capture earlier in the season, bottom melt, vulnerable extent south of 80N and upcoming potential for rough weather leads me in this direction.  This would also be in keeping with the "extension" (earlier start, later end) of the melt seasons we've been seeing progressively for possibly as long as a decade or more.

While there's still a chance we could make it to 2012, I think it will end up a 'near miss'.

The difference between the two (2020/2012) may more semantic than concrete, considering the overall current ice quality.

It will be interesting to see how close my assessment is to reality.

And to echo Neven - it's all about the melting momentum now.

I agree and also temperature forecasts according to AccuWeather seem to be 2 C-8 C above average from Siberia in Vyerkhoyansk and Svalbard Longyearbyen until September 30th. Equinox approximately 23-24th September.
« Last Edit: August 31, 2020, 11:27:29 PM by glennbuck »

VeliAlbertKallio

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Re: The 2020 melting season
« Reply #5618 on: August 31, 2020, 11:01:56 PM »
NSIDC 14-day sea ice extent reduction (due to melting and sea ice floe pulverisation) has been -64,000km2 per day if 85,000 km2 solitary 28.8. spreading event is eliminated from the series. Lesser scattering events may occur but these then will lead to further fragmenting below the 15% threshold.

There is heat in the ocean to melt the ice, but the buoy temperatures steadily fall. Barring major storm events it is near flat bottom of the melting curve for 2020. More questionable is Russian coasts where is more heat to dissipate to delay the refreeze. On the Atlantic Side, melting advances for weeks incrementally but is fully compensated in cooling air over the Central Arctic and North Pole forming ice.

I expect, nevertheless, rapid sea ice re-growth to occur facilitated by the widespread ice floes in Arctic.

More worrying is near Blue Ocean event next year and its forecast effect on the jet stream-driven rain belts moving in GCMs from a line north of the British Isles to the median around the Strait of Gibraltar, with the winter rain belts shifted to Morocco, Spain, Portugal, and Southern France, with the Beasts of the East, easterlies originating from Siberia brining very crispy air over Northern and Central Europe. The median occurrence in the models point to post-2021-melt circulatory change peaking by year end.

For general public 1,000,000 km2 BOE will appear cheating by experts and I would not market the event as such until the ocean is genuinely ice free (which I think is also just behind the corner as the last remaining ice bits to vanish take increasingly less energy due to diminished volume).

We need to readily assault against false climate change denialists' claims as surely they will come to haunt us 2021 if we claim blue ocean when there is million square kilometres of ice still left behind.

The surest sign of the final arrival of the Blue Ocean is when the Russian and American submariners are hugging in each other's arm pits under the very last ice floe - somewhere north of Canada.  :P
« Last Edit: August 31, 2020, 11:21:48 PM by VeliAlbertKallio »
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Re: The 2020 melting season
« Reply #5619 on: August 31, 2020, 11:35:53 PM »
Would a 2012-tier deviation from the trend of 2019/2020 result in a near BOE, or would there still be more room to fall? To phrase it differently, as 2020 appears to be progressing towards an in-trend approach (either this year or within the next few) to 2012 extent and area, has the risk of an outlier year causing even more extreme disruption increased?

To answer in very simplistic terms: 2012 saw a 1 million km2 drop from the year before (2011).  Assuming we see something in the range of 3.5 to 3.9 million km2 at the lowest point in 2020, *if* there was a similar 1 million km2 drop in 2021, we'd see something like 2.5 to 2.9 million km2.  Not yet threatening a BOE (defined as less than 1 million km2), but getting closer.

I may well be corrected by other people with more in depth analyses of your question, however.
This is using JAXA data. CAVEAT - all other things being equal.

2012's deviation from the linear trend was 1.5 million.
If you assume that was because 2012 saw an almost perfect set of circumstances, you can assume that 1.5 million is the maximum possible deviation possible,

The linear trend of the reduction in the minimum is circa 80-90k km2 per year.  So looking at say 2021, in 9 years that is circa 0.7 to 0.8 million km2 reduction in the expected value from the linear trend.
The 2012 minimum was 3.2 million km2, take off 0.8 million = 2.4 million km2 as the minimum possible in 2021.

BUT. The ice ain't what it used to be. Field evidence (MOSAIC etc), satellite data all say the ice is in awful shape.

So all other things are NOT equal. There is reason to at least hypothesise that a small change in the melting season weather favouring melt may produce a large increase in that melt.
One day volume will reduce to the extent (i.e. a tipping point) that sea ice area and extent losses must increase at a far greater rate (and that's just arithmetic).

A linear trend is a linear trend until... it isn't.
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Freegrass

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Re: The 2020 melting season
« Reply #5620 on: August 31, 2020, 11:39:45 PM »
A look back at the development of low concentration ice north of greenland, jun17-aug30 (amsr2-uhh sic)
I think I've finally figured out the gap north of Greenland. On your graphic you can clearly see how the GAAC moves the ice westwards. But on the east side of Greenland the ice bumps into Greenland and a strong current out of Fram. This causes the ice to rip apart, get stretched and weakend. This weak ice then melted out because of warm and powerful winds coming through Fram.

I think that's the story of the 2020 Greenland Gap.
More likely to be due to the ocean bumping into Greenland (and the shelves to the north) in my opinion.
Are you talking about the transpolar drift flushing the ice through Fram while the GAAC was blowing the ice to the west?

I'll leave it up to you guys to explain it correctly.
my bold in the second quote.
If you meant a strong current into the Fram then we are thinking along the same lines. Southerly winds played a big part then the thin ice has less damping effect on ocean turbulence at the shelf breaks which likely allows more mixing of returning atl water.
Let me try that again.

On your animation I can see two phases. Phase one is when the ice "bumped" into the eastside of north Greenland while on the other side the ice was being transported by the GAAC towards the west. This "stretched out" the ice north of Greenland. Ripping it apart so to speak.

Phase two was the weather system that blew hot southern air through fram, into that gap. This blew the eastern side of the ice to the northeast, away from Greenland, opening up the gap.

But during both phases I can see a continued loss of ice towards the Fram (Fram export). Probably due to the transpolar drift? But then we start going into details, and that's where I hand it off to you guys to explain it in more detail.
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Re: The 2020 melting season
« Reply #5621 on: August 31, 2020, 11:40:06 PM »
The August SIPN Sea Ice Outlook has finally been published:

https://GreatWhiteCon.info/2020/08/the-2020-arctic-sea-ice-minimum-extent/#Aug-31

Not much different to July at the end of the day:

Quote
The median August Outlook value for the September 2020 sea-ice extent is 4.30 million square kilometers, with quartile values of 4.1 and 4.5 million square kilometers.
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Re: The 2020 melting season
« Reply #5622 on: August 31, 2020, 11:48:53 PM »
Glennbuck posted this above.  This long stay at or above freezing between 80-90N.  Is amazing.  Even with solar insolation plummeting.

If any other year was like this someone please post about it.

This has to be super rare
 
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Re: The 2020 melting season
« Reply #5623 on: August 31, 2020, 11:53:44 PM »
Let me try that again.
Thanks. Ice bumping into Greenland as an explanation doesn't work for me.
edit: the event goes too far north
« Last Edit: September 01, 2020, 12:34:50 AM by uniquorn »

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Re: The 2020 melting season
« Reply #5624 on: August 31, 2020, 11:57:04 PM »
Glennbuck posted this above.  This long stay at or above freezing between 80-90N.  Is amazing.  Even with solar insolation plummeting.

If any other year was like this someone please post about it.

This has to be super rare

I think freegrass looked at it in earlier posts with a graph and it happened in the 1960,s but this year it is just sailing into the equinox beyond the 1960,s graph, probably unprecedented. Could be AGW or global dimming reduction from lockdown, future studies will probably find out the answer.
« Last Edit: September 01, 2020, 12:26:51 AM by glennbuck »

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Re: The 2020 melting season
« Reply #5625 on: September 01, 2020, 12:45:26 AM »
Glennbuck posted this above.  This long stay at or above freezing between 80-90N.  Is amazing.  Even with solar insolation plummeting.

If any other year was like this someone please post about it.

This has to be super rare

I think freegrass looked at it in earlier posts with a graph and it happened in the 1960,s but this year it is just sailing into the equinox beyond the 1960,s graph, probably unprecedented. Could be AGW or global dimming reduction from lockdown, future studies will probably find out the answer.
Those years when the DMI resembled this year for a few days were '64 and '79. But there is no comparison anymore. In 2012 the temperature dropped slowly, and in 2016 it came back to zero, but this year is unprecedented. In another thread I called the current state of the arctic a BOE version 0.1. Not a BOE 1.0 yet! But we're on our way to the real thing in pre-release...





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uniquorn

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Re: The 2020 melting season
« Reply #5626 on: September 01, 2020, 01:01:34 AM »
August 25-29.

2019.

That retreat north of Severnaya Zemlya is really spectacular, wow. And it's not over yet. Today and tomorrow there's a peak pressure gradient of 42 hPa, but according to ECMWF it will be 44 hPa at 120 hrs. The direction of the winds will shift a bit, but overall the ice pack should continue to get pushed towards the Pole.

This could easily become the highlight of this melting season! In many ways it's worse than 2012. And no GAC.

It will be very interesting if you explain in more detail what you are thinking. I will learn for sure. I don't see anything special with Freegrass' wind video.

I was referring to Aluminium's Uni Bremen SIC animation, more specifically to the retreat of the edge of the ice pack north of Severnaya Zemlya. It's really fast, even if the pressure gradient (due to dipole) isn't all that huge. But not small either, of course.

This will continue for several more days. If the ice edge makes it beyond 85N, it should make headlines. I agree the concentration loss between Greenland and the NP was spectacular too, but only for icewatchers like us, not to the general public. For that, it needs to be open water.

2020 made it to second place, without extreme weather. Melting momentum.
Not really headline stuff, but it's interesting how little SIC there is beyond the ice edge.

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Re: The 2020 melting season
« Reply #5627 on: September 01, 2020, 01:11:07 AM »
...

More worrying is near Blue Ocean event next year and its forecast effect on the jet stream-driven rain belts moving in GCMs from a line north of the British Isles to the median around the Strait of Gibraltar, with the winter rain belts shifted to Morocco, Spain, Portugal, and Southern France, with the Beasts of the East, easterlies originating from Siberia brining very crispy air over Northern and Central Europe. The median occurrence in the models point to post-2021-melt circulatory change peaking by year end.
...

IMO a very realistic assessment of a near BOE based on the actuality of the current status of the Arctic ice created by known metrics and implications regarding the Jet Stream.

+1 For the insight to 'connect the dots'
« Last Edit: September 01, 2020, 03:38:45 AM by D-Penguin »
Remember...it's all about the Jet Stream you dummy...just a personal reminder!

Freegrass

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Re: The 2020 melting season
« Reply #5628 on: September 01, 2020, 01:50:40 AM »
Latest Five Day Forecast
Wind + Temp @ Surface
Wind @ Surface + 3-hour Precipitation Accumulation
Large GiFS!
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Re: The 2020 melting season
« Reply #5629 on: September 01, 2020, 03:33:46 AM »
A look back at the development of low concentration ice north of greenland, jun17-aug30 (amsr2-uhh sic)
Fascinating - looking at the eastern coast of Greenland there appears to be a constant coastal flow north that creates 3/4 of a whirlpool action - ice flows move north then east as they reach the top of Greenland and then get pulled south into the general Fram export. This motion continues through the whole time frame of the GIF often at greater speeds than other ice in this picture.

In response to no storms this season comments:
While the season didn't have prolonged storms, the longevity of an almost arctic wide anticyclone from well before peak isolation and weeks after that peak is unique to this year and suggests there is 'more than one way to skin a cat.' And the post peak weather while not strong, kept importing heat from the south. The GAC of 2012 struck a very different arctic with much greater ice integrity; this modern arctic doesn't need as much energy input to move the ice around.

Final comment - a surprise to me has been the lack of Nares export even though the channel has been clear all summer. That has spread also to the rest of the CAA - to date very little ice from the CAB has been pushed into those channels - the flow has all been into the Beaufort replenishing that sea ice and making it the laggard. With current weather forecasts, that may be about to change, but there is still a lot of wind forecast to blow across the openings and not down them.

How different  could the arctic of 2012 be? Ice volume is the same as now
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Re: The 2020 melting season
« Reply #5630 on: September 01, 2020, 04:21:00 AM »
How different  could the arctic of 2012 be? Ice volume is the same as now

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

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

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Re: The 2020 melting season
« Reply #5631 on: September 01, 2020, 04:32:58 AM »
Does anyone have a clear idea of the Fram export capture zone? Looking at the development of the Atlantic and Laptev regions, and the retreat above 85N the export this winter will be significantly composed of 1st year ice?

I attempted to delineate the export areas for the last freezing season over at the Fram Export thread.  The results:

Quote
Red exits the Fram, blue into the Barents Sea, yellow into Nares Strait, and green into McClure Strait. It wasn't a very active season for Nares or the garlic press.

For me the takeaway is that melt in the Pacific and American sectors is much more consequential for multi-year ice than how far the ice edge retreats on the Atlantic or Laptev fronts.


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Re: The 2020 melting season
« Reply #5632 on: September 01, 2020, 05:04:14 AM »
August 27-31.

August 1-31 (fast).

2019.

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Re: The 2020 melting season
« Reply #5633 on: September 01, 2020, 05:09:09 AM »
whoi itp114 in the Beaufort. Microcat1 is mounted at 5m depth. Peaked at -0.665C today, avg closer to -0.75. Position is roughly centre of the worldview image.

Last buoy status on 2020/8/31 113047 UTC : temperature = -0.8125 °C, battery = 10.423 V
<snip>

Still seeing bottom melt.  That could easily be 1-1.5C a day pending on how well mixed the top 5-10M of water are.
You beat me to it.  I'd put it at about 1 cm/day.

The Beaufort & CAA are far enough south that they'll still have decent insolation for a few days as well.

2nd is looking very certain at this point, probably with room to spare.
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Re: The 2020 melting season
« Reply #5634 on: September 01, 2020, 05:14:35 AM »
August 27-31.

August 1-31 (fast).

2019.

Thank you for doing these..... they are really good and help see the events unfolding. I sometimes share them to people who don't know what is happening and they are very helpful.

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Re: The 2020 melting season
« Reply #5635 on: September 01, 2020, 05:18:25 AM »
August 27-31.
August 1-31 (fast).

As always thanks for the animations. I think the donut, or bagle, has become a curly tail.
I don't know what critter yet but it looks like it's dipping into the Fram for a drink.

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Re: The 2020 melting season
« Reply #5636 on: September 01, 2020, 05:28:20 AM »
If you meant a strong current into the Fram then we are thinking along the same lines.

And here I thought that the two well established currents in the Fram were the north-flowing West Spitzbergen Current in the Eastern half and the souht flowing East Greenland Current in the western half.

Two currents, one flowing out of the Fram strait and the other into the Fram, one northbound along the Svalbard coast and one southbound along the Greenland coast. Both currents are strong if fluctuating, ranging from 5 to 20 sverdrup (i.e. 5 - 20 million m3/s).

I'm totally unable to see how either current can be used to explain this summer's Greenland gap.
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Re: The 2020 melting season
« Reply #5637 on: September 01, 2020, 06:04:46 AM »
A look back at the development of low concentration ice north of greenland, jun17-aug30 (amsr2-uhh sic)
In response to no storms this season comments:
While the season didn't have prolonged storms, the longevity of an almost arctic wide anticyclone from well before peak isolation and weeks after that peak is unique to this year and suggests there is 'more than one way to skin a cat.' And the post peak weather while not strong, kept importing heat from the south. The GAC of 2012 struck a very different arctic with much greater ice integrity; this modern arctic doesn't need as much energy input to move the ice around.

How different  could the arctic of 2012 be? Ice volume is the same as now
2012 required the GAC to change the arctic ice in a fundamental way - while 2013-14 may have been 'recovery years' there has been no recovery for the huge reservoir of multi-year ice that dominated the arctic pre-2012 and what we now call 'multi-year' ice and track as it moves ever closer to extinction in the Beaufort is a pale substitute for what used to be referred to by that name.

Volume may be the same, but thickness and integrity of the pack is not. A little wind can do similar damage now to what required a GAC before.

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Re: The 2020 melting season
« Reply #5638 on: September 01, 2020, 06:08:40 AM »
Excellent explanation ATT! I've got one small niggle:

I don't think the brine pockets that are so common in fresh sea ice are "encapsulated in freezing water particles and incorporated into the ice". The brine stays

This website on oceanography has the following explanation:

Quote from: https://rwu.pressbooks.pub/webboceanography/
As sea ice crystals form, most of the salt is excluded, so sea ice contains much less salt than seawater, and can be melted for drinking if needed. But about 20% of the salt remains trapped in pockets of water between the ice crystals. As ice forms and salts are excluded into these pockets, the salinity of the remaining water increases and it can become too salty to freeze. These unfrozen pockets of briny water make sea ice a little softer and more slushy than fresh water ice, which is harder and more rigid. Eventually most of this brine leaks out, and the sea ice becomes more solid, but when it is “young ice” it can be more dangerous to walk on than fresh water ice of the same thickness. For example, 7-8 cm of fresh water ice is enough to support the weight of a single person, but you would need at least 15 cm of sea ice to do the same.


Nice addition binntho, looks like I needed just a bit more detail.

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Re: The 2020 melting season
« Reply #5639 on: September 01, 2020, 06:18:57 AM »
Had sometimes wondered if the record Greenland melt and record melt overall in 2012 freshened the Arctic and was a factor in the sea ice rebound in following years.  If it was a factor it is looking like less of one now since 2019 Greenland melt shattered the 2012 numbers.

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Re: The 2020 melting season
« Reply #5640 on: September 01, 2020, 07:48:23 AM »
The ice "rebounded" in 13/14 because the weather in JJA was very favorable for it to do so.


This summer also saw the warmest MJJ on record.   By a lot.  It torched all summer until the very end of July.

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Re: The 2020 melting season
« Reply #5641 on: September 01, 2020, 09:30:19 AM »
Always appreciate your ice concentration map gifs, thanks Aluminium.

Very interesting to see [Fig. 1] a couple of places in the ice of 1 August in the Beaufort Sea region where the centre of a Low has left  a 'scar' of reduced concentration -- presumably due to Ekman pumping.

Then look on 31 August [Fig. 2] & the scar is now a hole & the starting point for wider disintegration of the ice. Maybe the "fresh water lens" below the ice is destroyed by the Ekman pumping, and there are also more exposed edges, so further melting is easier in the scar.



Very tentative prediction as it is probably too late in the season, but there was another scar created by a low on 27 August, this time North of Greenland [Fig 3].


It will be interesting to see if it makes a hole.


On 25 August I had suggested it might make a hole ...
... a tight low precisely targeting the ice just north of Greenland. It might even make a big hole in the ice there.
... but for now it's just a scar -- even looking recovered by now & getting squashed against Greenland by the prevailing winds this week.


Anyway, I'm going to claim it as a prediction if, even so, it turns into a hole like the other 2 did!  ;)
« Last Edit: September 01, 2020, 09:40:49 AM by slow wing »

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Re: The 2020 melting season
« Reply #5642 on: September 01, 2020, 10:12:23 AM »
3.71 in data from the University of Bremen.

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

Freegrass

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Re: The 2020 melting season
« Reply #5643 on: September 01, 2020, 10:31:29 AM »
3.71 in data from the University of Bremen.

https://www.meereisportal.de/en/
Does this image end the debate about bathymetry and the ice edge? The ice edge clearly doesn't care about bathymetry...

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BornFromTheVoid

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Re: The 2020 melting season
« Reply #5644 on: September 01, 2020, 10:37:59 AM »
Today's images and slow animation (slightly larger version on twitter)...
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

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Re: The 2020 melting season
« Reply #5645 on: September 01, 2020, 10:40:18 AM »
Two concentration images, would let me add them in as an edit in the previous post...
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

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Re: The 2020 melting season
« Reply #5646 on: September 01, 2020, 10:48:42 AM »
3.71 in data from the University of Bremen.

https://www.meereisportal.de/en/
Does this image end the debate about bathymetry and the ice edge? The ice edge clearly doesn't care about bathymetry...


That is interesting. Usually, the periphery area such as Beaufort sea, East Siberian sea and Laptev sea are part of the continental shelf. Therefore, the sea water is much more easier to be heated in summer and temperature will rise relatively fast. The Arctic Basin is much deeper thus the sea water will not be heated so fast to melt the ice. The most interesting thing is that although the Arctic Basin is slow to be heated, it has more thermal capacity to trap more heat through the winter. The continental shelf region is easy to be heated meanwhile easy to be cooled when autumn comes.

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Re: The 2020 melting season
« Reply #5647 on: September 01, 2020, 11:01:36 AM »
3.71 in data from the University of Bremen.

https://www.meereisportal.de/en/
Does this image end the debate about bathymetry and the ice edge? The ice edge clearly doesn't care about bathymetry...


No, it doesn’t end the debate, at all. You can’t ignore all the compacting drift in July and the winds of lately. The bathymetry is the reason why there will remain ice in the CAB long after you get tired of making gifs. But this is all off topic now.

Freegrass

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Re: The 2020 melting season
« Reply #5648 on: September 01, 2020, 11:27:10 AM »
Bathymetry will give us a BOE. It doesn't save any ice anymore. It melts it. (I know that's way to simplistic, but I think you know what I mean)

Quote
The eastern Arctic Ocean's winter ice grew less than half as much as normal during the past decade, due to the growing influence of heat from the ocean's interior, researchers have found.

Typically, across much of the Arctic a thick layer of cold fresher water, known as a halocline, isolates the heat associated with the intruding Atlantic water from the sea surface and from sea ice.

This new study shows that an abnormal influx of salty warm water from the Atlantic Ocean is weakening and thinning the halocline, allowing more mixing. According to the new study, warm water of Atlantic origin is now moving much closer to the surface.

"The normal position of the upper boundary of this water in this region was about 150 meters. Now this water is at 80 meters," explained Polyakov.

Quote
The moorings measured the heat released from the ocean interior to the upper ocean and sea ice during winter. In 2016-2018, the estimated heat flux was about 10 watts per square meter, which is enough to prevent 80-90 centimeters (almost 3 feet) of sea ice from forming each year. Previous heat flux measurements were about half of that much.

https://phys.org/news/2020-08-arctic-ocean-winter-sea-ice.html
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binntho

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Re: The 2020 melting season
« Reply #5649 on: September 01, 2020, 11:49:44 AM »
Does this image end the debate about bathymetry and the ice edge? The ice edge clearly doesn't care about bathymetry...
I didn't know there still was a debate about bathymetry. I seem to remember having started just such a debate a few years ago, and after much heated argumentation and wild claims, I believe the real physics behind any link between the ice edge and bathymetry was teased out.

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

But these are secondary effects. There is no primary effect between bathymetry and the ice edge, and since a lot of other factors come into play as well, any link with bathymetry can only be considered transitory and weak.
because a thing is eloquently expressed it should not be taken to be as necessarily true
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