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binntho

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Re: The 2020 melting season
« Reply #5050 on: August 19, 2020, 07:18:13 AM »
With the latest Jaxa figures, second place seems increasingly likely (again!). Being of a stubborn nature and inflexible convictions, I haven't changed my prediction at all for several months and will repeat it here for everyones' unalloyed delight: This year will end in the upper half of the fourth million.
because a thing is eloquently expressed it should not be taken to be as necessarily true
St. Augustine, Confessions V, 6

Jim Hunt

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Re: The 2020 melting season
« Reply #5051 on: August 19, 2020, 07:24:32 AM »
Another century drop on jaxa.

Since I happen to be up and about reporting on the California "rolling blackouts", here's the latest graphic state of play:

https://GreatWhiteCon.info/2020/08/facts-about-the-arctic-in-august-2020/#comment-352315
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

miki

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Re: The 2020 melting season
« Reply #5052 on: August 19, 2020, 07:37:32 AM »
With the latest Jaxa figures, second place seems increasingly likely (again!). Being of a stubborn nature and inflexible convictions, I haven't changed my prediction at all for several months and will repeat it here for everyones' unalloyed delight: This year will end in the upper half of the fourth million.

I doubt it. But keep hoping.

Freegrass

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Re: The 2020 melting season
« Reply #5053 on: August 19, 2020, 08:35:40 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...

oren

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Re: The 2020 melting season
« Reply #5054 on: August 19, 2020, 09:11:50 AM »
Latest Five Day Forecast
Wind + Temp @ Surface
Large GiF!
In the Chukchi and Beaufort, something wicked this way comes in the later part of the forecast.

SirLurkALot

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Re: The 2020 melting season
« Reply #5055 on: August 19, 2020, 09:36:25 AM »
With the latest Jaxa figures, second place seems increasingly likely (again!). Being of a stubborn nature and inflexible convictions, I haven't changed my prediction at all for several months and will repeat it here for everyones' unalloyed delight: This year will end in the upper half of the fourth million.

I doubt it. But keep hoping.
I'm not an  expert, but have been following the discussion for quite some time.
Upper half of fourth million - so between 3.5 and 4.0 - seems plausible, given the state of play above. I guess whether the big SST anomalies at the  periphery will make it lower than 3.5 depends mainly on if the weather can mix warm water with the remaining ice.
I understand it took a big storm in 2012 to get below 3.5.



BornFromTheVoid

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Re: The 2020 melting season
« Reply #5056 on: August 19, 2020, 10:26:10 AM »
Latest daily change here.

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

pauldry600

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Re: The 2020 melting season
« Reply #5057 on: August 19, 2020, 10:27:29 AM »
I think once we start finishing under 4m regularly which seems likely this year and will likely continue in coming years we really are past the point of no return for extent if you look at the historical finishing figures. It's going 5million then 4million now 3millions. The countdown to BOE is well and truly underway.

MrGreeny

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Re: The 2020 melting season
« Reply #5058 on: August 19, 2020, 11:22:32 AM »
Hmm, not so sure about the rest of the season. Century drops have resumed, we only need a 1.5mil+ loss before the season ends. Could it be possible that 2020 will reach 1st? Not impossible. Could it be a close race? Most definitely.

Whether or not more of these century breaks happen is an answer the future holds.
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glennbuck

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Re: The 2020 melting season
« Reply #5059 on: August 19, 2020, 11:25:27 AM »
Looking at Piomas around 70% of remaining ice is 0.5m-1.5m Thickness.
« Last Edit: August 20, 2020, 12:48:51 AM by glennbuck »

binntho

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Re: The 2020 melting season
« Reply #5060 on: August 19, 2020, 11:40:14 AM »
There are two factors that will determine the final extent figure. One is how much ice area will melt away. I think it is fair to expect some tens of cms of melt until the end of the season, even up to or exceeding 0.5m in the peripheral areas.

But as we get nearer to the end of the season, dispersion will be the main thing to watch. Winds blowing northwards on the Pacific and Siberian side could quickly shave off several 100km2 of extent given how dispersed the ice is at the moment. In fact, I think we could reach a solid 2nd place without further melt, if the winds blow inwards for a week or two at the end of season.
because a thing is eloquently expressed it should not be taken to be as necessarily true
St. Augustine, Confessions V, 6

oren

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Re: The 2020 melting season
« Reply #5061 on: August 19, 2020, 11:40:58 AM »
Looking at this around 70% of remaining ice is 0.5m-1.5m Thickness.
Indeed. But at this late atage there is less than 0.5m of average melt remaining. Probably 0.3m on average (can do the math later). Of course this can be distributed unequally and there can be upside surprises as well.
OTOH, remaining thickness in each grid cell is an average, and there is lots of ice below the average. The distribution is highly skewed with a lot of the volume in a small fraction of the area. (Wipneus' gice chart)

SimonF92

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Re: The 2020 melting season
« Reply #5062 on: August 19, 2020, 11:45:44 AM »
Looking at this around 70% of remaining ice is 0.5m-1.5m Thickness.
Indeed. But at this late atage there is less than 0.5m of average melt remaining. Probably 0.3m on average (can do the math later). Of course this can be distributed unequally and there can be upside surprises as well.
OTOH, remaining thickness in each grid cell is an average, and there is lots of ice below the average. The distribution is highly skewed with a lot of the volume in a small fraction of the area. (Wipneus' gice chart)

If you do ever get round to doing that math I would very much like to see one does those kinds of calculations
Bunch of small python Arctic Apps:
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glennbuck

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Re: The 2020 melting season
« Reply #5063 on: August 19, 2020, 11:58:40 AM »
Looking at this around 70% of remaining ice is 0.5m-1.5m Thickness.
Indeed. But at this late atage there is less than 0.5m of average melt remaining. Probably 0.3m on average (can do the math later). Of course this can be distributed unequally and there can be upside surprises as well.
OTOH, remaining thickness in each grid cell is an average, and there is lots of ice below the average. The distribution is highly skewed with a lot of the volume in a small fraction of the area. (Wipneus' gice chart)

Interesting the melt left for the season, would 0.3m include top and bottom melt? Got an answer below from arctic ice August 2019.

Colleague Don Perovich discussed these issues at the International Glaciological Society: Sea Ice at the Interface meeting, held August 18 to 23, 2019 in Winnipeg, Canada. Surface melting peaks in July and usually ends in mid-August. By contrast, bottom melting peaks in August and often continues into September or October (Figure 4a).

https://nsidc.org/arcticseaicenews/2019/09/summers-not-over-until-bottom-melt-ends/
« Last Edit: August 19, 2020, 02:48:07 PM by glennbuck »

oren

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Re: The 2020 melting season
« Reply #5064 on: August 19, 2020, 12:05:07 PM »
My math is crude, don't hold your hopes too high.
In the CAB, average remaining volume loss (2007+) is 750 km3, 800 km3 if you remove low years. Remaining area is now around 2 mil km2. Ergo, average remaining melt is 0.4m.
Overall, average remaining volume loss (2007+) is 1100 km3, 1150 km3 if you remove low years. Remaining area is now around 3 mil km2. Ergo, average remaining melt is 0.37m.
This may be increased somewhat if taking average area from here to minimum.
The calculation is skewed by the fact that when there is no ice left volume loss starts to shrink. That's why I used only 2007 and later.

I would say most of this is bottom melt at this late date.

SimonF92

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Re: The 2020 melting season
« Reply #5065 on: August 19, 2020, 12:12:06 PM »
My math is crude, don't hold your hopes too high.
In the CAB, average remaining volume loss (2007+) is 750 km3, 800 km3 if you remove low years. Remaining area is now around 2 mil km2. Ergo, average remaining melt is 0.4m.
Overall, average remaining volume loss (2007+) is 1100 km3, 1150 km3 if you remove low years. Remaining area is now around 3 mil km2. Ergo, average remaining melt is 0.37m.
This may be increased somewhat if taking average area from here to minimum.
The calculation is skewed by the fact that when there is no ice left volume loss starts to shrink. That's why I used only 2007 and later.

I would say most of this is bottom melt at this late date.

Thanks, it makes a lot of sense!
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https://github.com/SimonF92/Arctic

gerontocrat

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Re: The 2020 melting season
« Reply #5066 on: August 19, 2020, 12:19:11 PM »
I haven't changed my prediction at all for several months and will repeat it here for everyones' unalloyed delight: This year will end in the upper half of the fourth million.

I doubt it. But keep hoping.
Just to get it straight

The fourth million is 3+ million to 4 million?
So the upper half of the fourth million is 3.5 to 4 million?

Sounds reasonable, but will the ice and the weather be reasonable?
« Last Edit: August 19, 2020, 01:10:25 PM by gerontocrat »
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BornFromTheVoid

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Re: The 2020 melting season
« Reply #5067 on: August 19, 2020, 12:31:28 PM »
Beaufort and Chukchi change over the last 12 days.
Bigger version on twitter: https://twitter.com/Icy_Samuel/status/1296031203162808320

(Edit: Sorry, gif was too small and autoplayed. Just put up a new one.)
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

gerontocrat

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Re: The 2020 melting season
« Reply #5068 on: August 19, 2020, 01:17:09 PM »
Looking at this around 70% of remaining ice is 0.5m-1.5m Thickness.
Indeed. But at this late atage there is less than 0.5m of average melt remaining. Probably 0.3m on average (can do the math later). Of course this can be distributed unequally and there can be upside surprises as well.
OTOH, remaining thickness in each grid cell is an average, and there is lots of ice below the average. The distribution is highly skewed with a lot of the volume in a small fraction of the area. (Wipneus' gice chart)

Interesting the melt left for the season, would 0.3m include top and bottom melt? Got an answer below from arctic ice August 2019.

Colleague Don Perovich discussed these issues at the International Glaciological Society: Sea Ice at the Interface meeting, held August 18 to 23, 2019 in Winnipeg, Canada. Surface melting peaks in July and usually ends in mid-August. By contrast, bottom melting peaks in August and often continues into September or October (Figure 4a).
But if surface air temperatures are late in falling to below zero (as is happening North of 80 at the moment) this will delay surface freezing from offsetting bottom melt, and reduce the rate of ocean heat loss from open water?
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

binntho

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Re: The 2020 melting season
« Reply #5069 on: August 19, 2020, 01:31:57 PM »
I haven't changed my prediction at all for several months and will repeat it here for everyones' unalloyed delight: This year will end in the upper half of the fourth million.

I doubt it. But keep hoping.
Just to get it straight

The fourth million is 3+ million to 4 million?
So the upper half of the fourth million is 3.5 to 4 million?

Sounds reasonable, but will the ice and the weather be reasonable?
The fourth million is indeed the million that starts after the third million.
because a thing is eloquently expressed it should not be taken to be as necessarily true
St. Augustine, Confessions V, 6

Freegrass

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Re: The 2020 melting season
« Reply #5070 on: August 19, 2020, 01:41:27 PM »
Latest Five Day Forecast
Wind @ Surface
Wind + Temp @ 850hPa
Large GiFS!

It looks like one of those horror scenarios that the long term GFS has been predicting for weeks now is finally coming to fruition.

Even the Euro agrees...
Now let's pray...

If the science don't fit our beliefs, we pray to God and cuddle up in our own delusional fantasy where everything makes sense again...

oren

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Re: The 2020 melting season
« Reply #5071 on: August 19, 2020, 01:56:23 PM »
My math is crude, don't hold your hopes too high.
In the CAB, average remaining volume loss (2007+) is 750 km3, 800 km3 if you remove low years. Remaining area is now around 2 mil km2. Ergo, average remaining melt is 0.4m.
Overall, average remaining volume loss (2007+) is 1100 km3, 1150 km3 if you remove low years. Remaining area is now around 3 mil km2. Ergo, average remaining melt is 0.37m.
This may be increased somewhat if taking average area from here to minimum.
The calculation is skewed by the fact that when there is no ice left volume loss starts to shrink. That's why I used only 2007 and later.

I would say most of this is bottom melt at this late date.

Just to complete the discussion, using the Wipneus thickness distribution charts included in my post upthread, very thick ice (2.6m and above) constitutes ~15% of ice area in mid-July, but ~50% of ice volume. Naturally, a lot of remaining ice has thickness below the local average shown by PIOMAS.


Comradez

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Re: The 2020 melting season
« Reply #5072 on: August 19, 2020, 02:21:46 PM »
Yeah, that's some brisk warm wind about to scream across the Chukchi Sea. 

It is interesting how, in the month of August, the Laptev and Atlantic fronts have only fallen back a little bit, whereas the Chukchi and Beaufort have just gotten thrashed. 

Yuha

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Re: The 2020 melting season
« Reply #5073 on: August 19, 2020, 03:14:40 PM »
A notification on Worldview:
Quote
The Aqua satellite experienced an anomaly on 16 August 2020 at 9:26:40 UTC and is affecting all Aqua MODIS and AIRS layers available in Worldview from 16 August 2020 onward. It is unknown when the issue will be remedied. We apologize for the inconvenience.

glennbuck

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Re: The 2020 melting season
« Reply #5074 on: August 19, 2020, 03:33:40 PM »
Looking at this around 70% of remaining ice is 0.5m-1.5m Thickness.
Indeed. But at this late atage there is less than 0.5m of average melt remaining. Probably 0.3m on average (can do the math later). Of course this can be distributed unequally and there can be upside surprises as well.
OTOH, remaining thickness in each grid cell is an average, and there is lots of ice below the average. The distribution is highly skewed with a lot of the volume in a small fraction of the area. (Wipneus' gice chart)

Interesting the melt left for the season, would 0.3m include top and bottom melt? Got an answer below from arctic ice August 2019.

Colleague Don Perovich discussed these issues at the International Glaciological Society: Sea Ice at the Interface meeting, held August 18 to 23, 2019 in Winnipeg, Canada. Surface melting peaks in July and usually ends in mid-August. By contrast, bottom melting peaks in August and often continues into September or October (Figure 4a).
But if surface air temperatures are late in falling to below zero (as is happening North of 80 at the moment) this will delay surface freezing from offsetting bottom melt, and reduce the rate of ocean heat loss from open water?

Yes very warm surface air temps for this time of year in the Arctic Ocean. 2016 surface air temp today vs 2020, 2018 and 2014. Surface Air Temp in green circle, Aug 19. That area is 4C - 6C for the next 5 days. Is the lower Aerosol masking effect, having an influence on the season this year?

Aug 19th                          Aug 20           Aug 21         Aug 22         Aug 23          Aug 24
 
2014    0.1 C                    -0.7                -0.4               -0.2               -0.4              -0.7
2015   -0.5 C                     0.7                -0.9                0.2               -0.3              -0.4
2016    0.9 C                     1.0                  0.9              -0.7               -1.9              -1.2
2017   -0.7 C                   -1.3                 -1.4              -1.3               -1.3               -0.7
2018    2.1 C                     3.0                  2.9               1.8                2.4                3.7
2019    2.1 C                     2.5                  2.9               1.4               -0.7               -0.7 
2020    6.0 C                     5.8                  5.4               4.4                4.7                4.7
« Last Edit: August 21, 2020, 11:54:44 AM by glennbuck »

Burnrate

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Re: The 2020 melting season
« Reply #5075 on: August 19, 2020, 04:38:50 PM »
It looks like the average position of the ice above Greenland hasn't moved very much over the past 7 days (just a bit SW on average).  It does seem to have lost quite a bit of the more fragmented ice while under the clouds as the wind has gone from heading west to east and back again.

Today is one of the least cloudy days since the 12th for that area but it's still hard to see everything there.  It looks like more of the same through the 23rd with the winds heading back east.  It will be interesting to see how that low moves and the winds in the later part of next week.  It could pull the ice up north a lot if it generates some strong southerly winds, it's so dispersed I would imagine it would be easy to move/compact/slosh.

I'm waiting to see when that huge floe breaks up.

Aluminium

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Re: The 2020 melting season
« Reply #5076 on: August 19, 2020, 05:17:05 PM »
August 4-18 (fast).

Was busy. Normal gif will be tomorrow.

pearscot

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Re: The 2020 melting season
« Reply #5077 on: August 19, 2020, 05:24:04 PM »
Call me crazy, but I think it might be possible where that triangle(ish) of ice skirting along Greenland's east coast fed by the Fram Straight might be severed by the next storm as the Atlantic front/melting to the North continue.

I've been watching it nonstop the last 2 months and everything just seems to continue degrading both areas.

The whole pack looks ragged as hell though. Even if we don't break a record I'm amazed at the action over the last 10 days or so.
pls!

vox_mundi

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Re: The 2020 melting season
« Reply #5078 on: August 19, 2020, 05:59:26 PM »
Polarstern seems intent on taking a close look at the North Pole in the near future:

Didn't take them long ...

Scientists on Arctic Mission Make Unplanned Detour to Pole
https://www.apnews.com/2b290e199aef10bd18683bb021133052

BERLIN (AP) — A German icebreaker carrying scientists on a year-long international expedition in the high Arctic has reached the North Pole, after making an unplanned detour because of lighter-than-usual sea ice conditions.

Expedition leader Markus Rex said Wednesday the RV Polarstern was able to reach the geographic North Pole because of large openings in sea ice that would normally make shipping in the region above Greenland too difficult.

“We made fast progress in a few days,” Rex told The Associated Press. “It’s breathtaking — at time we had open water as far as the eye could see.” ...
“There are three classes of people: those who see. Those who see when they are shown. Those who do not see.” ― Leonardo da Vinci

Insensible before the wave so soon released by callous fate. Affected most, they understand the least, and understanding, when it comes, invariably arrives too late

Burnrate

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Re: The 2020 melting season
« Reply #5079 on: August 19, 2020, 06:26:11 PM »

“We made fast progress in a few days,” Rex told The Associated Press. “It’s breathtaking — at time we had open water as far as the eye could see.” ...

Terrifying.

pearscot

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Re: The 2020 melting season
« Reply #5080 on: August 19, 2020, 06:29:35 PM »
Thanks for posting that, Vox!

This part tho...holy shit! (from the same article)

The region above northern Greenland is usually covered in thick sea ice that’s sometimes built up over several years, he said. But this year, the Polarstern was able to make it from the ice edge in the Fram Strait to the pole in less than a week."
pls!

CurtAdams

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Re: The 2020 melting season
« Reply #5081 on: August 19, 2020, 06:33:01 PM »
Yes very warm surface air temps for this time of year in the Arctic Ocean. 2016 surface air temp today vs 2020, 2018 and 2014. Surface Air Temp in green circle. That area is 4C - 6C for the next 5 days.

2014    0.1 C 
2016    0.9 C
2018    2.1 C
2020    6.0 C
Warmer than earlier years, sure, but there's no ice where your circle is. In general even in 2020 there are no areas with ice above freezing except a few areas off the Canadian Arctic Coast. This might slow refreezing in the fall, but record heat notwithstanding, top melt is still basically done.

glennbuck

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Re: The 2020 melting season
« Reply #5082 on: August 19, 2020, 06:37:48 PM »
Yes very warm surface air temps for this time of year in the Arctic Ocean. 2016 surface air temp today vs 2020, 2018 and 2014. Surface Air Temp in green circle. That area is 4C - 6C for the next 5 days.

2014    0.1 C 
2016    0.9 C
2018    2.1 C
2020    6.0 C


Warmer than earlier years, sure, but there's no ice where your circle is. In general even in 2020 there are no areas with ice above freezing except a few areas off the Canadian Arctic Coast. This might slow refreezing in the fall, but record heat notwithstanding, top melt is still basically done.

Surface air temperatures, we are not talking about ice temperatures, i imagine there was no ice where my circle is in most of the other years on August 19th.
« Last Edit: August 19, 2020, 08:02:54 PM by glennbuck »

grixm

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Re: The 2020 melting season
« Reply #5083 on: August 19, 2020, 07:33:43 PM »
August 4-18 (fast).

Was busy. Normal gif will be tomorrow.

Looks like Beaufort is primed for the chopping block, but I wonder if there is enough melt days left to see the same thing as we did in Chukchi and ESS.

Freegrass

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Re: The 2020 melting season
« Reply #5084 on: August 19, 2020, 07:42:07 PM »
Yes very warm surface air temps for this time of year in the Arctic Ocean. 2016 surface air temp today vs 2020, 2018 and 2014. Surface Air Temp in green circle. That area is 4C - 6C for the next 5 days.

2014    0.1 C 
2016    0.9 C
2018    2.1 C
2020    6.0 C
Warmer than earlier years, sure, but there's no ice where your circle is. In general even in 2020 there are no areas with ice above freezing except a few areas off the Canadian Arctic Coast. This might slow refreezing in the fall, but record heat notwithstanding, top melt is still basically done.
This year, we've added a lot of energy to the peripheral seas. But what about the CAB? Did compaction save it a little? Why hasn't the CAB completely collapsed this year when so much of the ice - and Polarstern - were flushed down Fram during winter and an unprecedented GAAC poured immense amounts of solar radiation into an ice pack that lost an unprecedented amount of ice in the peripheral seas during spring because temperatures in Siberia were record breaking because of clean air? (breath now)

I don't get it...

The GAAC compacted the CAB so much that open water was non-existing between the ice which prevented solar radiation to be sucked up by the ocean in between the ice. Instead, what wasn't sucked by ice cold melt ponds, was reflected back to space...

I'm with Binntho now. Storms could be as bad for the ice as sunshine.

I know, I know... Volume is at a record low... But soon we'll reset! I've learned here that the top layer of ice freezes rather quickly,  and then it slows down... So it'll all re-freeze with a thick layer of ice, that'll have to melt out all over again next year...

Nature is having a laugh with us!!! We think that in one lifetime we can see the ice disappear in the arctic. We want it like fast-food! But adding energy to the system takes a lot more time than some of us thought...

It's all about the weather now stupid!

<Removed some (mild) language.  O>
« Last Edit: August 19, 2020, 11:22:03 PM by oren »
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...

gandul

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Re: The 2020 melting season
« Reply #5085 on: August 19, 2020, 07:53:58 PM »
I don’t think so. The solar input level, combined with the warmth from Siberia, has provided a heat out of scale of previous years.
The CAB resists because it was extraordinary compacted and because it lacks ocean heat input that other areas receive. So as unprecedented as it was, the warming needed to really make it go is probably 2030-scale.
I completely agree on the catalytic effect of storms. Actually the weak but persistent one over ESS is adding insult to injury to the Chukchi sea I am sure.

Gray-Wolf

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Re: The 2020 melting season
« Reply #5086 on: August 19, 2020, 07:58:00 PM »
If i'm right back in 2012 we saw that Northern Greenland  Coastal strip of thick ice melt out over August? (5m ice from the plots IIRC?) and all from 'Bottom Melt'....

The wallop of energy we have seen go into the Arctic Basin this summer had the 'new' configuration of ice (for this time of year?) giving plenty of openings for direct transfer to the ocean below (even 1m ice transmits to the waters below I believe?) and so giving us these anomalously warm sst's

I fear that any storms that now arrive will just tumble the (ever smaller?) floes in a constantly replenishing supply of 'warm water' (over 4c?)?

The DMI 80N plot hints at what Polarstern has just confirmed for us, there is plenty of heat able to rise from the ocean beyond 80N!

I hope there are no sub 975 mb storms in the horizon......
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oren

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Re: The 2020 melting season
« Reply #5087 on: August 19, 2020, 08:07:09 PM »
August 4-18 (fast).

Was busy. Normal gif will be tomorrow.

Looks like Beaufort is primed for the chopping block, but I wonder if there is enough melt days left to see the same thing as we did in Chukchi and ESS.
It certainly looks as if the Beaufort will follow the impressive fate of the Chukchi and its near CAB sector. I think there is enough time left, the Beaufort can melt even after the general minimum due to its southerly location, and the forecasted winds will make it go quicker.

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Re: The 2020 melting season
« Reply #5088 on: August 19, 2020, 08:24:39 PM »
Some pretty incredible news from the North Pole today!

Below, is a photograph taken from the Polarstern at 12:45 pm on August 19, 2020 as the ship reached the North Pole. There are lots of melt ponds, and the ice that is left looks very thin.

Quote
”Based on the satellite imagery, at first we weren’t sure whether the loose ice cover was due to wind and currents, and were concerned that, if it was, a change in weather conditions could compact it again. Then we would have been caught in a mousetrap, and could have become trapped in the ice,” reports the MOSAiC Expedition Leader, who had previously reached the North Pole on board a research aircraft, in 2000. Once in the region, however, they found that much of the sea ice truly had melted away, and hadn’t simply been broken up by the wind.

https://www.awi.de/en/about-us/service/press/press-release/mosaic-expedition-reaches-the-north-pole.html




Glen Koehler

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Re: The 2020 melting season
« Reply #5089 on: August 19, 2020, 08:28:18 PM »
Surface melting peaks in July and usually ends in mid-August. By contrast, bottom melting peaks in August and often continues into September or October (Figure 4a).
https://nsidc.org/arcticseaicenews/2019/09/summers-not-over-until-bottom-melt-ends/

       Chart from link posted above is useful for assessing remaining melt season prospects.
Light blue bars are bottom melt.  Dark blue line is top melt.

      "Surface melting peaks in July and usually ends in mid-August. By contrast, bottom melting peaks in August and often continues into September or October (Figure 4a)."

     "Figure 4a. This 2005 to 2006 time series from the Beaufort Sea shows ice thickness (red line), growth rate (blue bars with negative values), bottom melt (blue bars with positive values), and surface melt (dark blue line with points). Both surface and bottom melt started on June 10. Surface melt peaked on August 1, and peak bottom melt was two weeks later on August 15. Surface melting ended on August 24, while bottom melting continued until October 24.
Credit: Don Perovich"
« Last Edit: August 19, 2020, 08:36:59 PM by Glen Koehler »

UCMiami

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Re: The 2020 melting season
« Reply #5090 on: August 19, 2020, 08:47:45 PM »
I am a very non-science based observer, but have lurked here for about 5 years with a few posts. The following may not hold water but what the hey -

I feel that the last fifteen years have truly changed the nature of arctic sea ice, but a lot of the systems and analysis was established as 'fact' before that change really manifested and to some degree it has yet to adjust. Pre-2007 the arctic sea ice remained 'land fast' even at minimum, but by 2012 the only connection to land was Greenland and the CAA islands. Since then even that connection has become intermittent and this year it has been almost non-existent for most of the summer.

The importance to me of the above is that pre2010 arctic ice movement except on the periphery was slow and measured - Ice forming on the Asian side took years to migrate toward Greenland where it either eventually exited the Fram/Nares or started to circle back toward Asia. Ice in the Beaufort got trapped into the gyre and circled back toward Greenland as multi-year ice.

This year looking at the speed with which Polarstern transversed from Asia to the Fram is a perfect illustration of the speed of arctic ice in this new era. Meanwhile no one really looks at the gyre because it is no longer a trap in which ice rotates year after year, but a transportation from the north of the CAA to oblivion for the remnants of 'older' ice. And with Greenland giving up its function as an anchor for the pack the other remnants of 'older ice' are moving towards the CAA and thence to their oblivion. The gyre is no longer tied to the Beaufort as peripheral ice movement but has in effect expanded to include the whole of the pack not destined for the Fram/Nares/Barents exit ramps.

The other aspect of this ice speed and the increased melt rate during melting seasons is that 'older' ice (I use quotes for a reason) is really limited to two year ice with maybe a few chunks interspersed that are older or formed from glaciers/collapsed ice shelves. Even the ice that is technically heading into a third winter this year has suffered so much top and bottom melt in its two summers that only a tiny fraction will be any thicker than the typical first year ice of 2000. And specific to the ice above Greenland - while this year may be extraordinary, the open water has been present for most of the past number of years so it was already fragmented and held together with a matrix of weaker ice. The disappearance of that ice was waiting for the right winds and temperatures and isolation which 2020 has provided.

Back to that second paragraph above - with a strong pack, slow movement and a melt season limited to the peripheral edges, extent with its simpler calculation was the best measure and quite accurate. As movement and melt increased, and the pack easily fragmented, area has become more accurate even with the calculation margins of error. The historic 'record' has validity, but at some point the extent measure becomes less and less relevant to the real life conditions. Additionally, volume measures (Piomas and others) are grounded in a 'solid pack' view of arctic ice and I believe struggle to deal with the 'real world' condition of the pack where 'thick ice' is actually a patchwork of loose flows held together by new and thin ice. Images from Polarstern seem to make this abundantly clear.

Freegrass

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Re: The 2020 melting season
« Reply #5091 on: August 19, 2020, 08:55:59 PM »
Latest Five Day Forecast
Wind @ Surface + Total Precipitable Water
Large GiF!
Now let's pray...

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HapHazard

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Re: The 2020 melting season
« Reply #5092 on: August 19, 2020, 09:31:15 PM »
Latest Five Day Forecast
Wind @ Surface + Total Precipitable Water

Gonna be "fun" for a few days...

ajouis

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Re: The 2020 melting season
« Reply #5093 on: August 19, 2020, 09:33:22 PM »
Yes very warm surface air temps for this time of year in the Arctic Ocean. 2016 surface air temp today vs 2020, 2018 and 2014. Surface Air Temp in green circle. That area is 4C - 6C for the next 5 days.

2014    0.1 C 
2016    0.9 C
2018    2.1 C
2020    6.0 C
Warmer than earlier years, sure, but there's no ice where your circle is. In general even in 2020 there are no areas with ice above freezing except a few areas off the Canadian Arctic Coast. This might slow refreezing in the fall, but record heat notwithstanding, top melt is still basically done.
Not according to the gfs 2m temperature forecast where half the arctic basin is consistently above 0 an there are not many areas wit temperatures below sea water freezing point, note that the areas above 0 change wildly too, leaving the whole basin to at least still get a taste of it
https://sites.google.com/site/arcticseaicegraphs/forecasts
After a thousand steps on the ice, it cracked.
The Man looked down at the infinite blue of the sea.
On the horizon, standing still, the polar bear had just scented his next meal.

 Less than 3000 cubic kilometers this Piomas minimum.

ajouis

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Re: The 2020 melting season
« Reply #5094 on: August 19, 2020, 09:37:16 PM »
PIOMAS gridded thickness data was updated to day 228 (15/16 August). Calculated volume on that day is 5.14 [1000km3], which means a third lowest place before 2012 and 2019.

Here is the animation for August thus far.

Quite a bit of that ice isn't there anymore, it also accounts for a lot of the weaker thinner ice glennbuck mentioned, so will we be able to trust piomas at minimum? Further if melts happen beyond normal parameters I think we can see how piomas model is like when stretched beyond its capabilities
After a thousand steps on the ice, it cracked.
The Man looked down at the infinite blue of the sea.
On the horizon, standing still, the polar bear had just scented his next meal.

 Less than 3000 cubic kilometers this Piomas minimum.

gerontocrat

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Re: The 2020 melting season
« Reply #5095 on: August 19, 2020, 09:54:20 PM »
Some pretty incredible news from the North Pole today!

Below, is a photograph taken from the Polarstern at 12:45 pm on August 19, 2020 as the ship reached the North Pole. There are lots of melt ponds, and the ice that is left looks very thin.

Quote
”Based on the satellite imagery, at first we weren’t sure whether the loose ice cover was due to wind and currents, and were concerned that, if it was, a change in weather conditions could compact it again. Then we would have been caught in a mousetrap, and could have become trapped in the ice,” reports the MOSAiC Expedition Leader, who had previously reached the North Pole on board a research aircraft, in 2000. Once in the region, however, they found that much of the sea ice truly had melted away, and hadn’t simply been broken up by the wind.

https://www.awi.de/en/about-us/service/press/press-release/mosaic-expedition-reaches-the-north-pole.html
Not much sign of compaction at the pole - and I don't think there ever was. Concentration does not mean compaction.

And the winter field evidence also suggests otherwise. the Mosaic expedition had a really bad time finding a floe to be their base - and it was never stable the whole winter. The Russians had to abandon their usual yearly camp near the North Pole. Those lunatic skiers were in permanent trouble. Concentration reached near as dammit 100% - but the ice was rotten.

And so far the Area and Extent losses in the Central Arctic Sea have been impressive, and concentration is very low.
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Freegrass

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Re: The 2020 melting season
« Reply #5096 on: August 19, 2020, 09:58:46 PM »
I don’t think so. The solar input level, combined with the warmth from Siberia, has provided a heat out of scale of previous years.
The CAB resists because it was extraordinary compacted and because it lacks ocean heat input that other areas receive. So as unprecedented as it was, the warming needed to really make it go is probably 2030-scale.
I completely agree on the catalytic effect of storms. Actually the weak but persistent one over ESS is adding insult to injury to the Chukchi sea I am sure.
The thing in bold is what I said, no?

I'm worried about the ESS as well with that warm ice free ocean being churned around by that continuous lineup of raging storms...
Now let's pray...

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marcel_g

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Re: The 2020 melting season
« Reply #5097 on: August 19, 2020, 10:08:56 PM »
Some pretty incredible news from the North Pole today!

Below, is a photograph taken from the Polarstern at 12:45 pm on August 19, 2020 as the ship reached the North Pole. There are lots of melt ponds, and the ice that is left looks very thin.
<snip>

https://www.awi.de/en/about-us/service/press/press-release/mosaic-expedition-reaches-the-north-pole.html

Wow, that ice is rotten. And as @gerontocrat says, that can't really be considered compacted, even if there are no big leads between the floes. That's a lot of melt ponds and rotten ice, and contrary to what @freegrass was saying, I don't think this state of compaction prevented much of July's solar insolation from getting into the water when such a high proportion is meltponds.

A high proportion of the solar energy would've passed right through those melt ponds and into the water, and the damage the sun caused is gobsmacking.

Now we get so see what happens if these wind events disrupt the water layers enough to bring heat up and cause more bottom melting, or if they're too late in the season.

Either way, it looks like huge swaths of the central pack are now rotten ice <50cm. Can you imagine what one more week of sunshine would've done?

Whatever ice survives this year will have done so by the skin of its teeth.



glennbuck

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Re: The 2020 melting season
« Reply #5098 on: August 19, 2020, 10:40:57 PM »
Surface melting peaks in July and usually ends in mid-August. By contrast, bottom melting peaks in August and often continues into September or October (Figure 4a).
https://nsidc.org/arcticseaicenews/2019/09/summers-not-over-until-bottom-melt-ends/

       Chart from link posted above is useful for assessing remaining melt season prospects.
Light blue bars are bottom melt.  Dark blue line is top melt.

      "Surface melting peaks in July and usually ends in mid-August. By contrast, bottom melting peaks in August and often continues into September or October (Figure 4a)."

     "Figure 4a. This 2005 to 2006 time series from the Beaufort Sea shows ice thickness (red line), growth rate (blue bars with negative values), bottom melt (blue bars with positive values), and surface melt (dark blue line with points). Both surface and bottom melt started on June 10. Surface melt peaked on August 1, and peak bottom melt was two weeks later on August 15. Surface melting ended on August 24, while bottom melting continued until October 24.
Credit: Don Perovich"

Nice info from charts 2005, shame he is using 13 year old graphs at a 2019 Conference, 2016-2018 would of been interesting compared to 2005, Arctic has changed so much in 13 years, it is far warmer in recent years which will effect top and bottom melt more compared to 2005 probably.

Glen Koehler

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Re: The 2020 melting season
« Reply #5099 on: August 19, 2020, 10:47:02 PM »
      The chart gave me info I did not know about those relationships and timings.  Yes every year is different and trend means that 2020 is different from 2005, but my guess is that the information about seasonal offset between top and bottom melt, and even the approximate dates for start, peak, and end dates for top and bottom melt is probably still reasonably accurate for 2020.