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oren

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Re: The 2020 melting season
« Reply #3400 on: July 22, 2020, 08:19:59 PM »
We are one month after the solstice, two months away from the equinox, which I think was the confusion.

Thomas Barlow

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Re: The 2020 melting season
« Reply #3401 on: July 22, 2020, 08:24:32 PM »
Does anyone have the direct link to Wipneus (ArctischePinguin) CAB (Arctic Ocean) sea-ice extent/area graph?
« Last Edit: July 22, 2020, 08:54:59 PM by Thomas Barlow »

KiwiGriff

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Re: The 2020 melting season
« Reply #3402 on: July 22, 2020, 08:25:00 PM »
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sailor

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Re: The 2020 melting season
« Reply #3403 on: July 22, 2020, 09:00:23 PM »

Starting august 1, the radiation balance tilts toward the negative side for most of the Arctic, just as around May 10 the opposite happened.
The reason open ocean does not start to refreeze immediately as it does in end of April is because there is an enormous amount of energy stored in the ocean, and atmospheric heat also has certain inertia.
Anyway I see August as the month where, for ice to melt, more importantly than being sunny, which is actually beneficial for ice as it allows infrared to escape, is that there are moderate to strong storms, not central, not persistent, as was mentioned above, but continuously dispersing and churning the ice in the marginal zone.

Freak ridges will probably be welcome by the ice past August 1st. I believe the people that have been in the forum for a while recognize this almost as a fact.

Perhaps the only configuration that is really bad and involves a strong ridge is forming a bad dipole that transports ice toward the Atlantic or toward the CAA channels. But insolation, subsidence, foehn winds and all that, very soon will be much less relevant.

By the way, tealight has a nice corrected version of the plot above.
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interstitial

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Re: The 2020 melting season
« Reply #3404 on: July 22, 2020, 09:02:14 PM »
To my eyes it shows an expectation that area/extent losses will slow, but that thinning will still be occurring
Hycom forecasts do not show area/extent losses in their forecasts. If there was Ice in a location the forecast will show at least the thinnnest ice. Their forecasts show thin ice turning white but never melting.

Thawing Thunder

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Re: The 2020 melting season
« Reply #3405 on: July 22, 2020, 09:03:56 PM »
I see August as the month where, for ice to melt, more importantly than being sunny, which is actually beneficial for ice as it allows infrared to escape, is that there are moderate to strong storms, not central, not persistent, as was mentioned above, but continuously dispersing and churning the ice in the marginal zone.

This or a real bad GAC like in 2012 which brought so much heat to the surface that it took two years for the arctic sea to get back to its new "normal". Or at least this is the way I interprete the 2013-2014 "rebound".
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FishOutofWater

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Re: The 2020 melting season
« Reply #3406 on: July 22, 2020, 09:23:08 PM »
The melting season in the CAA runs later than the central Arctic and is going to be in full swing over the next ten days as storms that develop on the coast of Alaska pull warm southerly winds up over the CAA and into the central Arctic. The storminess will also stir up heat in the Beaufort sea while dispersing the ice there. The melt season is shifting gears but it's a long way from done.

pearscot

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Re: The 2020 melting season
« Reply #3407 on: July 22, 2020, 09:28:59 PM »
The more I look at it, I think that 2020 is going to struggle to beat 2019. The ice is so compact at this point and I also think that the Beaufort has really avoided the absolute worst. There's just such a 'surplus' of ice in that region compared to last year I just don't foresee it overtaking it.

I'd be happy to be wrong, but after going back and comparing 2012 and 2019, the ice was so much more dispersed then.
pls!

ArcticMelt2

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Re: The 2020 melting season
« Reply #3408 on: July 22, 2020, 09:38:09 PM »
The more I look at it, I think that 2020 is going to struggle to beat 2019. The ice is so compact at this point and I also think that the Beaufort has really avoided the absolute worst. There's just such a 'surplus' of ice in that region compared to last year I just don't foresee it overtaking it.

I'd be happy to be wrong, but after going back and comparing 2012 and 2019, the ice was so much more dispersed then.

What about areas with black ice? Were these in 2012 or 2019 up to 86 degrees north latitude?
How thin is the ice in these areas? Could the current weak cyclone damage it?


Jim Hunt

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Re: The 2020 melting season
« Reply #3409 on: July 22, 2020, 09:54:16 PM »
Does anyone have the direct link to Wipneus (ArctischePinguin) CAB (Arctic Ocean) sea-ice extent/area graph?

See the top left corner of the regional graphs here:

https://sites.google.com/site/arctischepinguin/home/amsr2/grf
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marcel_g

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Re: The 2020 melting season
« Reply #3410 on: July 22, 2020, 09:57:35 PM »


What about areas with black ice? Were these in 2012 or 2019 up to 86 degrees north latitude?
How thin is the ice in these areas? Could the current weak cyclone damage it?

I'd like to know what this is too. Could those greyish areas be refrozen melt ponds? Or are they the greenish grey colour that lake ice turns to in April when it's all soft and rotten and just about to disappear?

There are large areas of ice like this north of Laptev, and there's a forecast for some wind to blow from Greenland to Laptev around day 5 or 6. Fortunately the wind isn't going to last very long, but it could cause some dispersion in this area.

wdmn

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Re: The 2020 melting season
« Reply #3411 on: July 22, 2020, 10:02:02 PM »
Looking at the individual sea data I calculate a pretty easy 700,000km2 to go by the end of the month, which would still leave us at about 400k ahead of 2019.

romett1

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Re: The 2020 melting season
« Reply #3412 on: July 22, 2020, 10:02:33 PM »
5 day difference - look how quickly dark and even white areas vanish over ESS.

Earlak

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Re: The 2020 melting season
« Reply #3413 on: July 22, 2020, 10:05:39 PM »

Starting august 1, the radiation balance tilts toward the negative side for most of the Arctic, just as around May 10 the opposite happened.


Do you have more details on the calculation behind these dates?
(I'm not doubting you, I'm just curious :D )

ArcticMelt2

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Re: The 2020 melting season
« Reply #3414 on: July 22, 2020, 10:06:23 PM »


What about areas with black ice? Were these in 2012 or 2019 up to 86 degrees north latitude?
How thin is the ice in these areas? Could the current weak cyclone damage it?

I'd like to know what this is too. Could those greyish areas be refrozen melt ponds? Or are they the greenish grey colour that lake ice turns to in April when it's all soft and rotten and just about to disappear?

There are large areas of ice like this north of Laptev, and there's a forecast for some wind to blow from Greenland to Laptev around day 5 or 6. Fortunately the wind isn't going to last very long, but it could cause some dispersion in this area.


I think it is ice that is close to melting completely. A similar color can be seen on the Siberian shelf at the fast ice in the June 14's images.

glennbuck

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Re: The 2020 melting season
« Reply #3415 on: July 22, 2020, 10:18:27 PM »
The more I look at it, I think that 2020 is going to struggle to beat 2019. The ice is so compact at this point and I also think that the Beaufort has really avoided the absolute worst. There's just such a 'surplus' of ice in that region compared to last year I just don't foresee it overtaking it.

I'd be happy to be wrong, but after going back and comparing 2012 and 2019, the ice was so much more dispersed then.

What about areas with black ice? Were these in 2012 or 2019 up to 86 degrees north latitude?
How thin is the ice in these areas? Could the current weak cyclone damage it?

Gerontocrat's update says For the minimum to be above 4.0 million km2,  remaining melt needs to be  24.0% or more below the previous 10 years average remaining melt.

Currently we are 17.2% more than the 10 year average

So to get above 4.0 million km^2 we need a 41.2% swing!

uniquorn

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Re: The 2020 melting season
« Reply #3416 on: July 22, 2020, 10:21:39 PM »
wipneus regional extent, laptev and surrounding seas, jul21

pearscot

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Re: The 2020 melting season
« Reply #3417 on: July 22, 2020, 10:26:23 PM »
The more I look at it, I think that 2020 is going to struggle to beat 2019. The ice is so compact at this point and I also think that the Beaufort has really avoided the absolute worst. There's just such a 'surplus' of ice in that region compared to last year I just don't foresee it overtaking it.

I'd be happy to be wrong, but after going back and comparing 2012 and 2019, the ice was so much more dispersed then.

What about areas with black ice? Were these in 2012 or 2019 up to 86 degrees north latitude?
How thin is the ice in these areas? Could the current weak cyclone damage it?

I can't dispute the changes and the ongoing melting, but in order for the record to be broken I think there really needs to be a substantial breakdown of the nice. Like I said, I would be happy to be proven wrong, but I'm going to wait until August 1st before really deciding how I think this year will end.

A week ago I felt like I had a better handle on it all, but the ice is an interesting state all around.
pls!

Yossarian80

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Re: The 2020 melting season
« Reply #3418 on: July 22, 2020, 10:28:02 PM »
Remarkable agreement between the GFS/Euro today... up to and beyond 7 days. A pattern shift will occur as low pressure dominates the CAB/Beaufort while HP builds on the Atlantic/Eurasian side resulting in a pretty significant -DA. Here’s what I’ll be watching closely during this pattern.

1. Like others have mentioned, a slowdown in losses will certainly occur, especially in extent. How big will the slowdown be? If losses only slow to near average, or even just slightly below, then that is further evidence of the power of “melting momentum.”

2. Despite the overall cloudier/cooler/dispersal pattern for most of the arctic, the CAA is going to get torched. I’d expect to see big losses there somewhat offsetting slowdowns elsewhere.

3. The strengthening -DA will result in stronger southerly offshore winds, and warm 850mb anomalies, north of Greenland and the northeastern CAA. The “cracks” in those areas will be interesting to watch, as they are already unprecedented and will likely grow even larger.

4. Will a strong cyclone develop on the Pacific side? Right now both the GFS/Euro are forecasting a 980mb LP on day 5. The storm doesn’t look too terrible, but if a bigger/stronger/persistent cyclone does develop in this area that would be trouble for the vast amount of vulnerable ice/rubble in the Beaufort.

uniquorn

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Re: The 2020 melting season
« Reply #3419 on: July 22, 2020, 10:42:17 PM »
Evidence of melting ribbons on the Laptev and Atlantic margins wherever one can peek through the clouds on Worldview.  Including these rather attractive tendrils N of Svalbard. Tendril length varies from 10-30km.  This Atlantic margin may not budge much, but it is being constantly supplied with ice, which duly melts as it meet warm Atlantic waters.
Nice pic.  Just west of there, a number of floes can be seen moving S. at what looks to me like 8-10 km/day.
A little while ago it was proposed that this 'constantly supplied ice' was ridging and thickening against the north Svalbard coast due to a repeated north south drift. Some of that thicker ice still remains visible in this image.
amsr2-uhh, nth svalbard, may1-jul21
« Last Edit: July 22, 2020, 11:48:20 PM by uniquorn »

FishOutofWater

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Re: The 2020 melting season
« Reply #3420 on: July 22, 2020, 10:56:21 PM »
Note that worldview shows cracks up and down the main channel and ice may be beginning to flow through the Davis strait. It certainly is cracking up and moving at the south end towards Baffin bay.

The dominoes are beginning to fall on the north American side of the Arctic.

Michael Hauber

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Re: The 2020 melting season
« Reply #3421 on: July 22, 2020, 11:04:13 PM »
Implications of a compact ice pack:

According to area and volume we are currently in 3rd position, and not a huge way ahead as we are for extent.  This implies the reason for the low extent is primarily compaction and not melt.  It implies that if the ice becomes as disperse as other years extent will also be 3rd in position.  With the weather suddenly turning favorable for ice retention, a new record is out of reach from 3rd position.

Lots of sunlight is being absorbed wherever the ocean is not covered in ice.  During this year that ocean is mostly on the fringes.  A large part of this heat energy will still be there come minimum, and the energy will be used for delaying the freeze season and not for causing a low minimum.  In contrast in a year like 2012 lots of sunlight is being absorbed by ocean within the ice pack which is then available for melting ice  within days or weeks as the ice moves around and over this water that had been warming in the sunlight.

And yes I expect the compaction to also result in some thickening due to ridging/stacking etc.  Whether this is enough to be important I don't know.  But do note that it is well accepted that ice can only grow to about 2m through thermodynamic processes, and ice only grows thicker than this through some form of ridging/compaction process.
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gandul

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Re: The 2020 melting season
« Reply #3422 on: July 22, 2020, 11:24:45 PM »
This storm will really upset Chukchi and Beaufort seas in day 4-6 according to Euro 12z, and GFS concurs.
The general flow will promote more melting in CAA, warmth over CAB and a sustained albeit overall small displacement of the pack toward the warmed Siberian seas.

uniquorn

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Re: The 2020 melting season
« Reply #3423 on: July 22, 2020, 11:28:03 PM »
Note that worldview shows cracks up and down the main channel and ice may be beginning to flow through the Davis strait. It certainly is cracking up and moving at the south end towards Baffin bay.
The dominoes are beginning to fall on the north American side of the Arctic.
Yes. Looking weak all the way to the Mclure Strait. Heavy linear contrast to show fractures.

glennbuck

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Re: The 2020 melting season
« Reply #3424 on: July 22, 2020, 11:32:31 PM »
Implications of a compact ice pack:

According to area and volume we are currently in 3rd position, and not a huge way ahead as we are for extent.  This implies the reason for the low extent is primarily compaction and not melt.  It implies that if the ice becomes as disperse as other years extent will also be 3rd in position.  With the weather suddenly turning favorable for ice retention, a new record is out of reach from 3rd position.

Lots of sunlight is being absorbed wherever the ocean is not covered in ice.  During this year that ocean is mostly on the fringes.  A large part of this heat energy will still be there come minimum, and the energy will be used for delaying the freeze season and not for causing a low minimum.  In contrast in a year like 2012 lots of sunlight is being absorbed by ocean within the ice pack which is then available for melting ice  within days or weeks as the ice moves around and over this water that had been warming in the sunlight.

And yes I expect the compaction to also result in some thickening due to ridging/stacking etc.  Whether this is enough to be important I don't know.  But do note that it is well accepted that ice can only grow to about 2m through thermodynamic processes, and ice only grows thicker than this through some form of ridging/compaction process.

This data from 21st of July 2019 was within 20,000 km^2 off the September minimum.



This data on July 21st 2020 has September 2020 at 3.24 million km^2 to 3.29million^2 from the five to ten year average.


« Last Edit: July 23, 2020, 12:43:44 AM by glennbuck »

wdmn

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Re: The 2020 melting season
« Reply #3425 on: July 22, 2020, 11:39:40 PM »
Implications of a compact ice pack:

According to area and volume we are currently in 3rd position, and not a huge way ahead as we are for extent.  This implies the reason for the low extent is primarily compaction and not melt.  It implies that if the ice becomes as disperse as other years extent will also be 3rd in position.  With the weather suddenly turning favorable for ice retention, a new record is out of reach from 3rd position.

Lots of sunlight is being absorbed wherever the ocean is not covered in ice.  During this year that ocean is mostly on the fringes.  A large part of this heat energy will still be there come minimum, and the energy will be used for delaying the freeze season and not for causing a low minimum.  In contrast in a year like 2012 lots of sunlight is being absorbed by ocean within the ice pack which is then available for melting ice  within days or weeks as the ice moves around and over this water that had been warming in the sunlight.

And yes I expect the compaction to also result in some thickening due to ridging/stacking etc.  Whether this is enough to be important I don't know.  But do note that it is well accepted that ice can only grow to about 2m through thermodynamic processes, and ice only grows thicker than this through some form of ridging/compaction process.

You keep repeating arguments that have already been addressed, or are otherwise nonsense.

1) Area is less reliable of a measure than extent during the summer. Obviously the GAAC causes compaction, which was the consensus before the event even started. But we have also witnessed melt out in areas that did not melt last year, such as the CAA, which is clearly not due to compaction. jdallen provided some imagery re this subject also.

2) The ice always melts from the outside in, so to say that "this year" the open water is "on the fringes" is absurd. There is more open water surrounding the ice than ever before at this date.

3) We already had the conversation about ridging/stacking. Unless you have new evidence to add that goes against the paper provided by Lodger or what was presented in the thread, please stop repeating this misleading, unsubstantiated claim.

gandul

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Re: The 2020 melting season
« Reply #3426 on: July 22, 2020, 11:41:49 PM »
This data from 21st of July 2019 was within 20,000 km^2 of the September minimum.Following chart has September 2020 at 3.24 million km^2
Please, get these tables  out of this thread, they occupy too much space, please simply add a link to the post of the data thread

glennbuck

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Re: The 2020 melting season
« Reply #3427 on: July 23, 2020, 12:28:31 AM »
This data from 21st of July 2019 was within 20,000 km^2 of the September minimum.Following chart has September 2020 at 3.24 million km^2
Please, get these tables  out of this thread, they occupy too much space, please simply add a link to the post of the data thread

For the minimum to be above 4.0 million km2,  remaining melt needs to be  24.0% or more below the previous 10 years average remaining melt.

Thomas Barlow

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Re: The 2020 melting season
« Reply #3428 on: July 23, 2020, 12:37:26 AM »
Does anyone have the direct link to Wipneus (ArctischePinguin) CAB (Arctic Ocean) sea-ice extent/area graph?

See the top left corner of the regional graphs here:

https://sites.google.com/site/arctischepinguin/home/amsr2/grf
Great, thanks.
This is the one I was looking for. Near bottom of list.
Look at the damn thing!  Am I misinterpreting this?
Looks dramatic.
As I've always said on here, it's really only the Arctic Ocean that matters (not the N. Hemisphere sea-ice extent - interesting as that is). eg. there could still be ice in the CAA even in a Blue Ocean Event (which is decades away, but with much upheaval at the poles and for the planet before then)

https://14adebb0-a-62cb3a1a-s-sites.googlegroups.com/site/arctischepinguin/home/amsr2/grf/basin-extent-multiprod.png?attachauth=ANoY7cqjsYVCFYp-Atht1A9yuwsQ6ra8-YnoMn42ihQtI-3bbjmRNrdOXYsTYYe5-nhvVLnB4axCmCzQ4fFc5mDU8ilgZ1Qal0Krqh5BgGCg-zsd34dqEwhoiCV3p2qTLoFZeYJI_q3bnrC6XaN16qVy-xHXpcHuV86y8gD4dGLxq7K-Z0zFnFOkdH1mDKvH6NBMEfL2bUlttG4r0htahZQqzRUzURIPaphdDO2gpEAww1H1pb17N08DWz9I3HCPe0BYEfSAfg2-&attredirects=0
« Last Edit: July 24, 2020, 03:09:07 AM by Thomas Barlow »

Tom_Mazanec

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Re: The 2020 melting season
« Reply #3429 on: July 23, 2020, 12:38:08 AM »
Quote
According to area and volume we are currently in 3rd position, and not a huge way ahead as we are for extent.  This implies the reason for the low extent is primarily compaction and not melt.  It implies that if the ice becomes as disperse as other years extent will also be 3rd in position.  With the weather suddenly turning favorable for ice retention, a new record is out of reach from 3rd position.
Do you expect a 2nd place, MH?
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Michael Hauber

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Re: The 2020 melting season
« Reply #3430 on: July 23, 2020, 12:43:57 AM »
Do you expect a 2nd place, MH?

1st-highly unlikely
2nd- good chance but weather will need a spell of favourable melt conditions at some stage
3rd or lower - quite possible if weather stays favourable for ice retention.
Climate change:  Prepare for the worst, hope for the best, expect the middle.

Michael Hauber

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Re: The 2020 melting season
« Reply #3431 on: July 23, 2020, 12:51:11 AM »

1) Area is less reliable of a measure than extent during the summer. Obviously the GAAC causes compaction, which was the consensus before the event even started. But we have also witnessed melt out in areas that did not melt last year, such as the CAA, which is clearly not due to compaction. jdallen provided some imagery re this subject also.
Area is less reliable than extent.  So it is just as likely as not there is even more ice than the current area stat suggests.

2) The ice always melts from the outside in, so to say that "this year" the open water is "on the fringes" is absurd. There is more open water surrounding the ice than ever before at this date.

Not if you have a look at the MODIS images and compare to other years.

3) We already had the conversation about ridging/stacking. Unless you have new evidence to add that goes against the paper provided by Lodger or what was presented in the thread, please stop repeating this misleading, unsubstantiated claim.

http://psc.apl.uw.edu/research/projects/projections-of-an-ice-diminished-arctic-ocean/model/

Ridging/stacking is important enough that PIOMAS explicitly models it.
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Ice Shieldz

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Re: The 2020 melting season
« Reply #3432 on: July 23, 2020, 01:19:18 AM »
Michael, would you be so kind to summarize from the article how ridging occurs in summer months?

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Re: The 2020 melting season
« Reply #3433 on: July 23, 2020, 01:45:01 AM »
The more I look at it, I think that 2020 is going to struggle to beat 2019. The ice is so compact at this point and I also think that the Beaufort has really avoided the absolute worst. There's just such a 'surplus' of ice in that region compared to last year I just don't foresee it overtaking it.

I'd be happy to be wrong, but after going back and comparing 2012 and 2019, the ice was so much more dispersed then.

What about areas with black ice? Were these in 2012 or 2019 up to 86 degrees north latitude?
How thin is the ice in these areas? Could the current weak cyclone damage it?

I can't dispute the changes and the ongoing melting, but in order for the record to be broken I think there really needs to be a substantial breakdown of the nice. Like I said, I would be happy to be proven wrong, but I'm going to wait until August 1st before really deciding how I think this year will end.

A week ago I felt like I had a better handle on it all, but the ice is an interesting state all around.


You were talking about 2019 and the record was in 2012. Could it be that there was a typo or a glitch while writing.


Your post would make a lot of sense if the year you mentioned were 2012 but for 2019 it's of course possible but very unlikely that this year will stay around or above 4M km2

Juan C. García

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Re: The 2020 melting season
« Reply #3434 on: July 23, 2020, 01:46:31 AM »
1st-highly unlikely
2nd- good chance but weather will need a spell of favourable melt conditions at some stage
3rd or lower - quite possible if weather stays favourable for ice retention.
With one million km2 difference between 2010's average and 2020 (JAXA numbers that are more accurate than NSIDC on the last 10 years), I discard the 3rd place.

From now, still more chance of 2nd than 1st, but I think that the ice is not in good shape. I am concerned about Chukchi and Beaufort.  Last Bremen image doesn’t look good. It can be just noise. We have to wait for the other images on July.

At the end, it will be just a flip of a coin, depending on weather. If a GAC develops on the first 10 days of August on the right place, 1st place will be more likely.
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

Greenbelt

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Re: The 2020 melting season
« Reply #3435 on: July 23, 2020, 01:50:07 AM »
Regarding compaction or not, I keep going back to the Polarstern pic from late June.  If ice like that is being regarded as compact, I think it could in fact pack together a lot tighter.  Click for high res.

igs

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Re: The 2020 melting season
« Reply #3436 on: July 23, 2020, 01:51:26 AM »
1. Like others have mentioned, a slowdown in losses will certainly occur, especially in extent. How big will the slowdown be? If losses only slow to near average, or even just slightly below, then that is further evidence of the power of “melting momentum.”

I'd dispute that word certainly and replace it with perhaps or probably.

That said it depends a bit what everyone understand with a slowdown in losses. for a day or two it's most proble but not necessarily for much longer and a 2 days pump in the curve is not a real slowdown in case the melt shall resume it's speed as it did many years in the past at this time of the year.

As I wrote upthread. We are more than a week from August and independent of the weather, curves at the end of july were often quite stable (not straight down of course) because the air is still above freezing, bottom melt does it's job and the slightes dispersion can lead to immediate poof of that few centimeters thick small icefloes.

So the certainly has to be seen and the slowdown has to be defined more closely so that we're talking about the same.

Glen Koehler

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Re: The 2020 melting season
« Reply #3437 on: July 23, 2020, 03:07:44 AM »
Do you expect a 2nd place, MH?
1st-highly unlikely
2nd- good chance but weather will need a spell of favourable melt conditions at some stage
3rd or lower - quite possible if weather stays favourable for ice retention.

      Given gerontocrat's summary below, I think that "good chance" for 2nd (i.e. 3.96M km2 JAXA Extent) is a very, very good chance:
<snip> In every year from 2007 to 2019 remaining melt results in an extent below 3.96 million km2, which was the 2nd lowest extent in 2019.

     But the ice does not care what we say about it.  It will tell us exactly how much it will melt over the next few weeks. 
     This poem comes to mind:

   Ice asks no questions, 
      presents no arguments,
         reads no newspapers,
           listens to no debates.
     
    It is not burdened by ideology,
       and carries no political baggage
           as it changes from solid to liquid.

    It just melts.

                                 ~ Henry Pollack
------------------
   
  But of course, we like to guess at the future. 
     Here are some measures of our predictive ability:

      Improved Volume prediction accuracy as melt season observations become available.
R-square reduction in variability derived from R values posted by Stephan at https://imgur.com/a/O82kzZZ

      Linear model estimate for 2020 September average PIOMAS Volume before any 2020 observations:
 3.9M km3 (1.2 – 6.6), (95% of cases expected to fall within 1.2 – 6.6M km3, i.e.  +/- 2.7M km3).
   
      With MARCH observation as predictor, confidence interval (CI) reduction for September average Volume estimate: 4%.  Width of 95% CI with March observation: +/- 2.6M km3.
      With APRIL Volume observation, confidence interval reduction: 7%.  Width of 95% CI with April observation: +/- 2.5M km3.
      With MAY Volume observation, confidence interval reduction: 32%.  Width of 95% CI with May observation: +/- 1.9M km3.
      With JUNE Volume observation, confidence interval reduction: 63%.  Width of 95% CI with June observation: +/- 1.0M km3.
      With JULY Volume observation, confidence interval reduction: 83%.  Width of 95% CI with July observation: +/- 0.5M km3.
      With AUGUST Volume observation, conf. interval reduction: 94%.  Width of 95% CI with August observation: +/- 0.2M km3.

      The same approach for Extent shows the R2 reduction by having observations at the end of March, April and May is insignificant.  Estimate error reduction only reaches 22% by the end of June, and 56% at the end of July.

Thawing Thunder

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Re: The 2020 melting season
« Reply #3438 on: July 23, 2020, 03:29:41 AM »
What about areas with black ice? Were these in 2012 or 2019 up to 86 degrees north latitude?
How thin is the ice in these areas? Could the current weak cyclone damage it?

It's very rotten ice. I followed it back to the 25th of July and found it already broke up then but got recompressed. But there isn't probably any coherency, it is like powder floating on the surface.

Here a snapshot of that date:
The Thunder was father of the first people, and the Moon was the first mother. But Maxa'xâk, the evil horned serpent, destroyed the Water Keeper Spirit and loosed the waters upon the Earth and the first people were no more.

wdmn

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Re: The 2020 melting season
« Reply #3439 on: July 23, 2020, 03:32:13 AM »
Michael,

I'd like to preface this by saying that I don't even like to guess at where the season will finish, because it seems like an easy way to be wrong about one more thing in life. I have made some predictions about the end of the month, which are modest and based off of long term loss patterns for the various arctic seas. So I am not claiming to know about what position this year will finish in, and your belief in 3rd place or above is not really what bothers me. What I find slightly off putting about your posts is the degree of certainty you speak with, in spite of the fact that many long term observers on this forum have put forward evidence that should at least make you question your conclusions. Also, you never admit when called out on something (such as your comment about the open water being "mostly on the fringes").

As for your specific replies:

Why would it be just as likely that there is more area and not less given the record low extent? You're treating this as a logical problem (area could be either higher or lower, so there's 50% chance each way), whereas such a statement must be justified empirically.

I would like to compare to 2019, for example, but 2019 had a low pressure system over the arctic for almost all of July, so it's difficult to make comparisons for most of the ice. Clearly the Beaufort was in worse shape in 2019, but that's about all that is clear (other than that way more momentum has been built up this year due to insolation).

As for the ridging/rafting, no one was questioning that this happens, so your PIOMAS link offers nothing to the discussion. A paper was already put forward on the difference in the mechanics between rafting and ridging. The question was whether we could expect this to occur during melt season on structurally compromised ice, due to compaction. You haven't provided any new information on that question.

Thawing Thunder

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Re: The 2020 melting season
« Reply #3440 on: July 23, 2020, 03:33:40 AM »
Regarding compaction or not, I keep going back to the Polarstern pic from late June.  If ice like that is being regarded as compact, I think it could in fact pack together a lot tighter.  Click for high res.

I think that's exactly how this dark ice looks like. You can even spot these small round polynyas on Worldview.
The Thunder was father of the first people, and the Moon was the first mother. But Maxa'xâk, the evil horned serpent, destroyed the Water Keeper Spirit and loosed the waters upon the Earth and the first people were no more.

Yossarian80

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Re: The 2020 melting season
« Reply #3441 on: July 23, 2020, 03:34:42 AM »
1. Like others have mentioned, a slowdown in losses will certainly occur, especially in extent. How big will the slowdown be? If losses only slow to near average, or even just slightly below, then that is further evidence of the power of “melting momentum.”

I'd dispute that word certainly and replace it with perhaps or probably.

That said it depends a bit what everyone understand with a slowdown in losses. for a day or two it's most proble but not necessarily for much longer and a 2 days pump in the curve is not a real slowdown in case the melt shall resume it's speed as it did many years in the past at this time of the year.

Losses on jaxa the last 7 days have averaged 126k, and 127k for the month of July. Nothing is ever 100% certain I suppose, especially when it comes to meteorology and the cryosphere, but given the forecast over the next week some kind of slowdown from those lofty numbers seems very, very likely; barring some sort of GAC beyond day 4. How much is anybody’s guess, but I do agree that tons of heat has already been added to the system, which should reduce the slowdown via bottom melt and momentum. That said, I would be very surprised if we averaged over 100k in losses on jaxa for the next 7 days, but we’ll see... the arctic has definitely surprised and humbled me many times before.

I’m pretty indifferent to the arguments about compaction/dispersion... I think most of that is just ice moving around which affects the numbers, but usually not the actual physical state of the ice. But I do like the idea that dispersal could be bad for the ice now, given how much heat the surrounding water has absorbed recently. That does seem to make sense logically and physically, and could be detrimental to the ice even if not reflected in the extent numbers.

wdmn

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Re: The 2020 melting season
« Reply #3442 on: July 23, 2020, 04:01:24 AM »
Victoria Strait (SE of Victoria Island in the CAA) was clear today. Below is a video of changes from July 16 to today (just two frames, as it was cloudy on the other days).

Click to play.

wallen

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Re: The 2020 melting season
« Reply #3443 on: July 23, 2020, 04:59:56 AM »
The number of people here  that appear to be suddenly jumping off the record melt band wagon. The high that hung around for ever and a day has moved and Jaxa finally had a sub 100k day. 99k(Shock horror) .

Meanwhile 2020 as at 21/7 was still 626k lower than any other year. Looking at  the AMSR 2 image for 22/7, I wont be surprised if it jumps up again, as the ESS appears to have vanished over night.

 Gerontocrats data(As at 21/7) shows that just average melt will still see an extent of 3.29million km2 . For it to finish 4+ million km2, it would have to have 24% less than average melt.

The heat built into the waters particularly on the Russian side, most certainly isn't going to disappear in a blink.

While the weather patterns aren't showing a super doom high. It hasn't backed off to non melting conditions. Don't know what temperatures are occurring in the various regions, but the anomalies look to to be reasonably high.

I certainly am no scientist of any type, but even to a blind Freddie like me, it is likely to take something special to stop the rest of this melt season in it's tracks.

Whether it breaks 2012 is to be seen, but it has a been a season to remember, with a lot to learn from and still a long way to go.

« Last Edit: July 23, 2020, 05:42:59 AM by wallen »

wdmn

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Re: The 2020 melting season
« Reply #3444 on: July 23, 2020, 05:43:58 AM »
After a 117k km2 loss in JAXA extent today, I wonder how long it would take the ice to change from moving in a way that leads to compaction to moving according to the new weather pattern.

In other words, when can we start ruling out compaction as a (primary) factor in the 100k+ daily extent losses?

P.S. I ask this question sincerely, not in a snarky way.

Pagophilus

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Re: The 2020 melting season
« Reply #3445 on: July 23, 2020, 05:50:27 AM »
I have been thinking about what you wrote here, oren.  It set me to thinking that the words 'compact' and 'compaction' are being asked to do far too much work.  I am one of the guilty parties (sigh).  The confusions we had are likely to form again, and I think I saw that building even in some subsequent replies.

Maybe, when we mean, as I did in this case, that floes are being moved closer together, we should write exactly that, or write that the ice is becoming more concentrated (in its areal distribution). 

Perhaps compaction should be reserved for the meaning of ice being so tightly pushed together that it becomes thicker (through pressure ridging etc.).

And maybe there is already formal professional guidance on this issue.



I think there is a miscommunication here. The ice is/was "compacting", meaning it was generally moving towards the center of the pack, as an expected result of the high pressure and anti-cyclonic winds. I think all/most posters agree on that.
However, is the ice compact, meaning with no small holes inside the pack? I think many posters are saying no, it is not compact, since area has disappeared while the ice was moving northward, thus there is less ice covering a smaller extent.
Is the ice strong and defensible? I think many posters are saying no.
And have ice floes stacked on top of one another due to the northward movement, as happens with pressure ridges in winter? I think most/all posters now agree that no.
Person.  Woman.  Man.  Vote.  November.

Viggy

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Re: The 2020 melting season
« Reply #3446 on: July 23, 2020, 06:15:21 AM »
I dont see how one can look at the forecast for the next 7 days and summarize that it would be good for the ice. I also think the whole compactness discussion is moot given how mobile the ice pack has been but the next week can shed a lot more light on that discussion as well.

We literally have a polar dipole positioned in such a way from days 2 - 7 that it continuously pushes CAB ice from the Kara to the Chukchi seas, rotating over the Laptev and ESS in the process. The waters there are incredibly warm so I see sea ice dispersing and getting destroyed. If by some miracle, the CAB is significantly more 'compact' than we imagine, then the extent decreases should almost stop due to dispersion of this supposedly thick, compact ice. The higher pressure over the Kara and Barents should also cause dispersion by pulling the ice into their centers.

I think the severity of the season should be pretty apparent by then and on track for a new record but just for good measure, both the GFS and ECMWF are showing HPs reestablishing over the entire Arctic after day 8 ...

ajouis

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Re: The 2020 melting season
« Reply #3447 on: July 23, 2020, 06:20:26 AM »
I do not agree with the above statements that we are most likely on track for second place. We have had unprecedented continued extent losses that give us almost a million on 2012, the amount it lost during the second cliff btw, and we are not third in area, in high res we are still first. Piomas is only a model, and as I have shown on the artifact thread the conditions we are in were not even anticipated by the best predicting model, slater’s, with a very big gap now between it and reality, so I din’t think we can expect it to show what is right until thinning to zero has occurred in a big enough way for lower res nsidc to pick it up.
My own prediction is outlandish (below 3000 cubic kilometers) but ending up first in area and extent is the most reasonable, especially taking into account melt momentum and accumulated insolation
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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.

Glen Koehler

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Re: The 2020 melting season
« Reply #3448 on: July 23, 2020, 07:00:41 AM »

      While some allowance must be made for possible sensor misinterpretation, the July 21 NSIDC ASI concentration map makes the Beaufort look like a fortress ready to fall.
« Last Edit: July 23, 2020, 04:49:56 PM by Glen Koehler »

GoSouthYoungins

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Re: The 2020 melting season
« Reply #3449 on: July 23, 2020, 07:06:50 AM »
Ppl on this forum thinking ice that turned blue/grey in June is fine. Okay. 3rd place! Sure.

The Eastern Siberian Lowlands is on fire. The whole macro region is just flaming hot. The siberian seas are warm, the permafrost is thawing, and everything is burning.

Looks good to me. I don't think modern civ will be unliveable until the 2030s. So whatever, the melt isn't that bad.
big time oops