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Phoenix

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Re: The 2020 melting season
« Reply #2300 on: July 07, 2020, 01:03:36 AM »

I'm afraid I don't see it.  As long as we have surface temps at or above zero and insolation, the havoc will continue unabated.  I see no respite.

So, you're of the opinion that a surface temperature of 0.5C and 2.0C will yield the same melt rate, all other factors being equal?

My sense is that a stronger temperature gradient between the ice and surrounding air will lead to a faster rate of energy transfer.
The direct transfer of heat from atmosphere to ice is trivial compared to that delivered by insolation. 

There has been a discussion on this topic earlier in the season which I link to in a separate thread below. It includes links to peer reviewed field research papers that quantify incremental melting impacts of heat waves to be greater than the impact of lost insolation when heat waves arrived under cloudy conditions.

https://forum.arctic-sea-ice.net/index.php/topic,3106.0.html

I don't disagree that insolation is extremely important and am not arguing that melt is going to be slow by any standard measure. I'm just saying that surface temps and WAA are not a trival factor.


Rod

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Re: The 2020 melting season
« Reply #2301 on: July 07, 2020, 02:40:28 AM »
Dr. Judah Cohen has posted a new long term outlook for arctic weather patterns.

It is very technical (I have read it three times and I still don’t understand it), but some of our amateur meteorologists might enjoy reading it.

“Arctic Oscillation and Polar Vortex Analysis and Forecasts
July 6, 2020”

https://www.aer.com/science-research/climate-weather/arctic-oscillation/

Some highlights:

“Impacts

Certainly, one of the biggest if not the biggest weather news story of the summer so far has been the high-pressure system/heat dome that setup over Siberia in June leading to record breaking high temperatures and wildfires across Siberia.  The exceptional warmth has caused sea ice to melt at a record pace in the Laptev Sea adjacent to Siberia and has contributed to an overall acceleration of sea ice melt for the entire Arctic basin over the past several weeks.  That high pressure system that sat over Siberia for much of June has now drifted into the Central Arctic centered near the North Pole.

Therefore, the circulation pattern in the Central Arctic is likely to be very different from recent Julys.  The circulation in the Central Arctic has been dominated by low pressure resulting in relatively cloudy, cool weather.  So even though Arctic sea ice at the end of the winter was at or near record low extent no new record annual minimums have been observed since 2012 because summer low pressure in the Central Arctic slowed sea ice melt. However, at a minimum for the first half of July, the Central Arctic will be dominated by high pressure favoring relatively sunny and warm weather, which is conducive to accelerated sea ice melt.  There does seem to be a higher probability that the sea ice minimum in 2020 will be lower than recent summers and may even challenge the record low of summer 2012.”


I also thought this comment was interesting based on some discussions upthread:

“Longer Term

30–day

The latest plot of the polar cap geopotential height anomalies (PCHs) currently shows normal to above normal PCHs in both the troposphere and the lower stratosphere with normal to below normal PCHs in the mid-stratosphere (Figure 11).  However, PCHs in the lower stratosphere are predicted to reverse to normal to below normal while PCHs in the troposphere are predicted to remain mostly positive (Figure 11).  The GFS forecasts of a reversal to cold stratospheric PCHs have been overdone much of the spring and I wouldn’t consider the forecast reliable.”

The first Figure below is Figure 11.  The second one is Figure 13 in the article.

« Last Edit: July 07, 2020, 04:03:28 AM by Rod »

Paul

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Re: The 2020 melting season
« Reply #2302 on: July 07, 2020, 02:54:12 AM »
indeed Jim .. also a great day to look back at 2013 .. it looked like the end of the world in comparison to today .. yet it has become 'just another year' . b.c.

2013 was protected by the outer ice being slow to melt therefore all the dispersion that occurred that year did not come into play but it was a close run thing by the end of August as the CAB ice was full of holes quite extensively by then.

When one looks at the entirety of the 7 seas of the High Arctic a complementary story emerges. I attach a table of High Arctic sea ice area as at the 5th July. 2013 area is 1.17 million km2, 17.9% above the 2020 area for this date, and 19th lowest. How contrary was 2013 to show such high signs of melt in the Central Arctic Sea while the High Arctic seas outer ring do not.

Thats the flaw in the NSIDC charts, it does not pick up dispersion very well at all. You only need too look at the worldview charts for the end of August in 2013 too see how the dispersion right now in July turned into a shocker by then. If that outer ice melted quicker, any warmer SSTS would of attacked that quite vulnable ice quite easily imo but it was literally saved by the bell and the water frozed and the ice pack was quite extensive in the end. Of course at the other end of the scale, years 2012 and 2016 was not so fortunate and in particular 2016 ice pack looked awful.

It's why I still have the theory dispersion in the longer term is worse than perhaps melt ponds and compaction. Last year had a more compact pack but still finish 2nd lowest but I believe very warm SSTS played it part then and we could see similar this year as the SSTS are quite high in the Laptev sea. If there was more ice in the Laptev sea and the ESS i would say even getting under 4 million could be a big ask but I do think it's quite likely this year.

echoughton

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Re: The 2020 melting season
« Reply #2303 on: July 07, 2020, 03:02:36 AM »
Last year wasn't 2nd lowest in extent. Not even close. Or am I wrong again?

Pagophilus

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Re: The 2020 melting season
« Reply #2304 on: July 07, 2020, 03:03:15 AM »
Dr. Judah Cohen ....

“Impacts

Certainly, one of the biggest if not the biggest weather news story of the summer so far has been the high-pressure system/heat dome that setup over Siberia in June leading to record breaking high temperatures and wildfires across Siberia.  The exceptional warmth has caused sea ice to melt at a record pace in the Laptev Sea adjacent to Siberia and has contributed to an overall acceleration of sea ice melt for the entire Arctic basin over the past several weeks.  That high pressure system that sat over Siberia for much of June has now drifted into the Central Arctic centered near the North Pole.

Therefore, the circulation pattern in the Central Arctic is likely to be very different from recent Julys.  The circulation in the Central Arctic has been dominated by low pressure resulting in relatively cloudy, cool weather.  So even though Arctic sea ice at the end of the winter was at or near record low extent no new record annual minimums have been observed since 2012 because summer low pressure in the Central Arctic slowed sea ice melt. However, at a minimum for the first half of July, the Central Arctic will be dominated by high pressure favoring relatively sunny and warm weather, which is conducive to accelerated sea ice melt.  There does seem to be a higher probability that the sea ice minimum in 2020 will be lower than recent summers and may even challenge the record low of summer 2012.”
Thanks Rod.  Dr Cohen's clear, confirming summary was useful to me.
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Rod

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Re: The 2020 melting season
« Reply #2305 on: July 07, 2020, 03:06:09 AM »
Last year wasn't 2nd lowest in extent. Not even close. Or am I wrong again?

https://www.google.com/amp/s/www.carbonbrief.org/arctic-sea-ice-minimum-in-2019-is-joint-second-lowest-on-record/amp

This is NSIDC data.  I’m sure someone else will quickly pull the JAXA data.
« Last Edit: July 07, 2020, 03:22:25 AM by Rod »

Pagophilus

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Re: The 2020 melting season
« Reply #2306 on: July 07, 2020, 03:14:04 AM »

I'm afraid I don't see it.  As long as we have surface temps at or above zero and insolation, the havoc will continue unabated.  I see no respite.

So, you're of the opinion that a surface temperature of 0.5C and 2.0C will yield the same melt rate, all other factors being equal?

My sense is that a stronger temperature gradient between the ice and surrounding air will lead to a faster rate of energy transfer.
The direct transfer of heat from atmosphere to ice is trivial compared to that delivered by insolation. 

There has been a discussion on this topic earlier in the season which I link to in a separate thread below. It includes links to peer reviewed field research papers that quantify incremental melting impacts of heat waves to be greater than the impact of lost insolation when heat waves arrived under cloudy conditions.

https://forum.arctic-sea-ice.net/index.php/topic,3106.0.html

I don't disagree that insolation is extremely important and am not arguing that melt is going to be slow by any standard measure. I'm just saying that surface temps and WAA are not a trival factor.

An added factor: insolation is significant, but it is multiplied in its significance by lower albedo.  As shown in the graph Aluminium posted in his recent message (#2233), the daily high arctic warming potential, which takes albedo into account, has gone through the roof.

Couldn't lower surface temps over the next few days in these sunny conditions be partly or wholly 'compensated for' by this factor?

EDIT  I have just posted the most recent Daily High Arctic Warming Potential graph (replacing the previous one here) as per Phoenix's comment below.  https://cryospherecomputing.tk/NRTawp.html
« Last Edit: July 07, 2020, 06:46:51 AM by Pagophilus »
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Rod

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Re: The 2020 melting season
« Reply #2307 on: July 07, 2020, 03:14:49 AM »
Thanks Rod.  Dr Cohen's clear, confirming summary was useful to me.

👍🏻

(The emojis in the main menu are limited. I hope everyone can see the thumbs up, and people are not scratching their head wondering why I reposted without saying anything.  I’m on IOS, so I always wonder what the Android users can see).

Phoenix

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Re: The 2020 melting season
« Reply #2308 on: July 07, 2020, 04:24:21 AM »

An added factor: insolation is significant, but it is multiplied in its significance by low albedo, and as Aluminium posted in message 2233, the daily high arctic warming potential, which takes this into account, has gone through the roof.  I repost the graph here because it seems important to remember in this debate..

Thanks for reposting the graph Pagophilus. Let's be clear though that there is zero disagreement here regarding the importance of insolation which is generally higher in a high pressure regime as we currently find ourselves in (and potentially turbocharged by a covid based reduction in aerosol blocking).

The debate is only about the incremental importance of surface temperatures which are forecast to decline in a few days.

Note: The version of the graph you have posted has been updated and the new daily AWP anomaly,  while still very high, has declined from yesterday's peak for both the High Arctic as a whole and for the CAB region. You can view it here.

https://cryospherecomputing.tk/NRTawp.html

Question for the gallery: If someone can explain the algebra that Nico Sun (aka tealight) uses to calculate AWP, please chime in.

oren

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Re: The 2020 melting season
« Reply #2309 on: July 07, 2020, 05:17:53 AM »
As far as I can recall, Nico Sun's model does not know if melt ponds are present. I believe it knows if open water, ice or snow-covered ice are present in each grid cell, and uses an albedo number for each of these, based on NSIDC data. it also does not know if conditions are cloudy or sunny, but it does know the level of insolation by latitude and date for each grid cell. Normally AWP reaches record highs when area reaches record low, but depending on ice distribution.
It's a great model and a very useful tool, but it cannot answer what is being asked here.
If someone could dig the discussion held on the forum at the time of creating the web site, it could be quite useful. There might be some documentation on the site as well. I would suggest a new thread, Albedo-Warming Potential, to discuss this in detail and to understand what the model does or doesn't do. Coming to think of it, he may have made such a thread himself at the time. Look for posts by user "Tealight".

Edit: see below for the link to the thread. Thanks sedziobs.

I also believe insolation in early July is much more important than a degree or two of air temps, especially when albedo is as low as it is now. But obviously higher air temps contribute their share to melting.

If my failing memory is correct, 2019 was 2nd on record for JAXA extent (only one below 4 M km2 except 2012), and a very respectable 2nd in total PIOMAS volume after 2012. However it did not reach 2nd for area (that was 2016) and did not manage to make a big dent specifically in the CAB (that was 2016 too). It led in all parameters in July and "deserved" to do better but had a cold August and no GAC.
« Last Edit: July 07, 2020, 05:27:11 AM by oren »

sedziobs

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Re: The 2020 melting season
« Reply #2310 on: July 07, 2020, 05:20:35 AM »
Question for the gallery: If someone can explain the algebra that Nico Sun (aka tealight) uses to calculate AWP, please chime in.

Have a look through Tealight's AWP thread: https://forum.arctic-sea-ice.net/index.php/topic,1749.0.html

And the precursor Albedo thread: https://forum.arctic-sea-ice.net/index.php/topic,1543.0.html

As for the insolation/temp discussion, I'd say temperature is less of a factor under high pressure due to the dryness of descending air. Under cloudy skies, humidity is likely greater, and therefore energy transfer can be be significant with slight temperature increases.

romett1

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Re: The 2020 melting season
« Reply #2311 on: July 07, 2020, 05:26:04 AM »
Uni Bremen July 6 - North Pole  :o

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Re: The 2020 melting season
« Reply #2312 on: July 07, 2020, 05:49:46 AM »
Some big cracks appearing in the Perry Channel today, indicating the start of the collapse of fast ice in that region. Looking at past years on WorldView, this is not unusual for this time of the year. Still something to keep an eye on given the overall state of the ice pack.

Yes, definitely something to watch, personally will hold off worrying about the Perry Channel for now.  The ice there seems to have held its own the last few years.  Seems like the Beaufort has held up better the last few years too.  Most of the action seems to be on the Russian side.  My previous comment about coastal ice being absent from Kara and Laptev may need to be extended to ESS and Chukchi soon.

Is the Northern Route open, if not surely imminent?

May be delusional but almost looks like a polynya is trying to open in the CAB north of FJL and SZ!  If so will that be unprecedented?!

Rod

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Re: The 2020 melting season
« Reply #2313 on: July 07, 2020, 06:11:24 AM »


The debate is only about the incremental importance of surface temperatures which are forecast to decline in a few days.


This is a total straw man argument that no one but you is making, and the physics and thermodynamics do not support anything you say.

Instead, focus on something that really happened. In May, we had an unprecedented high that primed the ice for melting. You fought with Friv about it over and over. Friv was right. 

The high pressure system at the end of May helped precondition the ice, and that is why things we are seeing now are even worse.

There is a lot that can still happen this year. Maybe we get close to a record and maybe not, but quit shifting your target.

We will see what happens.
« Last Edit: July 07, 2020, 07:03:23 AM by Rod »

Juan C. García

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Re: The 2020 melting season
« Reply #2314 on: July 07, 2020, 06:17:50 AM »
It seems that the high pressure system and the lack of aerosols are adding up. It is going to be an interesting second half of the melting season.
[ADS NIPR VISHOP (JAXA)] Arctic Sea Ice Extent.

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Re: The 2020 melting season
« Reply #2315 on: July 07, 2020, 06:28:10 AM »
Compaction is a strong extent killer and makes for big headlines. The more important questions at this stage are what happens with area - which also dropping fast, and especially volume/thickness - which one can only imagine is breaking some daily records.
I note that wind-induced Fram export has not started yet. The smaller Nares is already half empty and racing for the exit.

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Re: The 2020 melting season
« Reply #2316 on: July 07, 2020, 06:33:28 AM »
Wasn’t 2020 a middle of the pack melting year on extent just a few days ago?  Am I looking at the numbers wrong, could 2020 be in the pole position by like Wed. if the rate of melt continues!  Since the ESS bulge is definitely feeling the big pinch ( That seems like a recurrent pattern to me ) and the Hudson Bay belly looks to be the coastal spine only soon, this looks probable to me.

It is interesting how some aspects of melt happen in somewhat predictable patterns year after year and some things are totally unpredictable.

Hudson usually seems to melt from North and East crescent leaving a south west bulge.  A strip of open water forms separating the bulge from the coast, then the bulge starts to give way leaving a southwestern strip of offshore ice as last to go.

Foxe basin also seems to do nearly the same thing every year.  North melts fast then the south catches up and finally the eastern “donut” gets slowly whittled down.

Baffin Bay, also, nearly the same pattern, every year.

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Re: The 2020 melting season
« Reply #2317 on: July 07, 2020, 06:40:36 AM »
<snip>
https://www.google.com/amp/s/www.carbonbrief.org/arctic-sea-ice-minimum-in-2019-is-joint-second-lowest-on-record/amp

That is a bad link Rod, sending readers to Google. The clean link is: /www.carbonbrief.org/arctic-sea-ice-minimum-in-2019-is-joint-second-lowest-on-record
(to all) Please stay alert and post clean links.
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Rod

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Re: The 2020 melting season
« Reply #2318 on: July 07, 2020, 06:46:23 AM »
Sorry nanning. I just copied and pasted. I tested the link after I posted it, and it worked on my phone.

That was what I was getting at earlier with potential problems if we use different operating systems.


Phoenix

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Re: The 2020 melting season
« Reply #2319 on: July 07, 2020, 06:54:18 AM »
Question for the gallery: If someone can explain the algebra that Nico Sun (aka tealight) uses to calculate AWP, please chime in.

Have a look through Tealight's AWP thread: https://forum.arctic-sea-ice.net/index.php/topic,1749.0.html


Thanks for the link sedziobs. Nico's work is a great resource for us.

Pagophilus

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Re: The 2020 melting season
« Reply #2320 on: July 07, 2020, 07:15:07 AM »

An added factor: insolation is significant, but it is multiplied in its significance by low albedo, and as Aluminium posted in message 2233, the daily high arctic warming potential, which takes this into account, has gone through the roof.  I repost the graph here because it seems important to remember in this debate..

Thanks for reposting the graph Pagophilus. Let's be clear though that there is zero disagreement here regarding the importance of insolation which is generally higher in a high pressure regime as we currently find ourselves in (and potentially turbocharged by a covid based reduction in aerosol blocking).

The debate is only about the incremental importance of surface temperatures which are forecast to decline in a few days.

Note: The version of the graph you have posted has been updated and the new daily AWP anomaly,  while still very high, has declined from yesterday's peak for both the High Arctic as a whole and for the CAB region. You can view it here.

https://cryospherecomputing.tk/NRTawp.html

Question for the gallery: If someone can explain the algebra that Nico Sun (aka tealight) uses to calculate AWP, please chime in.

Phoenix, I do not have the data to show whether you are correct or not.  This is as you say not a matter of saying insolation is not significant, but rather one of questioning how much difference air temperature can make.   All I have is personal experience, so I am just going to ramble on about that for a bit... 

I can feel freezing in winter when standing in the shadows, and then walk out into the sunshine and start feeling warmer after just a few seconds.  The air has not got any warmer (and BTW I doubt I would be able to tell the difference between .5C or 2C).  But I do know that the sunlight hitting my jacket and pants and skin and hat is being converted to heat and the effect is considerable, despite the uniform coldness of the air around me.. Of course sunlight hitting grayish ice and being partially absorbed is mostly not converted to heat.  Instead the absorbed solar energy (potentially round the clock in this case) is largely 'employed' in melting the ice.  The air above the ice is not warmed much, but the ice sure changes.  So I would go with insolation and albedo as being more important in this instance (Arctic midsummer, projected high insolation).  And I do recognize my argument may be flawed because it is only on this experiential basis.
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Re: The 2020 melting season
« Reply #2321 on: July 07, 2020, 07:34:06 AM »
Wow Sea ice extent is now 220K km2 below the next closest year.

That's amazing.  The forecast is straight insanity.

The day 10 image on the 00z euro is UNREAL.  WOULD BE TRULY EPIC.
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Re: The 2020 melting season
« Reply #2322 on: July 07, 2020, 08:28:17 AM »
Wow Sea ice extent is now 220K km2 below the next closest year.

That's amazing.  The forecast is straight insanity.

The day 10 image on the 00z euro is UNREAL.  WOULD BE TRULY EPIC.
That the models could even postulate this 10 days out is staggering.

It is absolutely insane.  If it happens, it's time to pray fervently for divine intervention for the ice.
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Re: The 2020 melting season
« Reply #2323 on: July 07, 2020, 08:48:48 AM »
July 2-6.

2019.

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Re: The 2020 melting season
« Reply #2324 on: July 07, 2020, 09:19:07 AM »
Compaction is a strong extent killer and makes for big headlines. The more important questions at this stage are what happens with area - which also dropping fast, and especially volume/thickness - which one can only imagine is breaking some daily records.
I note that wind-induced Fram export has not started yet. The smaller Nares is already half empty and racing for the exit.

Well this image from June 30 in the physics.org article:

https://phys.org/news/2020-07-latest-mosaic-floe.html

about the unusually thin ice Mosaic has encountered is the first I have seen them release giving an honest view of conditions. Not the usual puff pieces about haircuts and how well resetting up all the equipment is going, or cute polar bears.
This area was getting cooled winds from the mid basin and probably less sizzle than most anywhere else in CAB so not looking flash. Also rocks and shelfish thawing out of the central fortress floe show it is ex ESAS fast Ice, and they report most ice in region was only around 50cm, compared to 1.6m usually found in same area where they started in late 1990s.
Stones thawed out of fortress also attach.

Phoenix

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Re: The 2020 melting season
« Reply #2325 on: July 07, 2020, 09:37:41 AM »
Wow Sea ice extent is now 220K km2 below the next closest year.

That's amazing.  The forecast is straight insanity.

The day 10 image on the 00z euro is UNREAL.  WOULD BE TRULY EPIC.
That the models could even postulate this 10 days out is staggering.

It is absolutely insane.  If it happens, it's time to pray fervently for divine intervention for the ice.

OK...what is epic about the 10 day forecast? I see a temp forecast at 850 hpa. Google tells me this is generally about 1.5km above sea level, above the boundary layer.

If I open the GFS forecast and look what's doing in 10 days at sea level, I see the warm spots wherever this is open water in the forecast and all the ice covered areas are actually pretty mild at 0.0 - 1.0C.

https://climatereanalyzer.org/wx/fcst/#gfs.arc-lea.t2

If we're going to characterize things as "absolutely insane", maybe a little explanation of which feature of the forecast is insane is in order?

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Re: The 2020 melting season
« Reply #2326 on: July 07, 2020, 09:50:36 AM »
Wow Sea ice extent is now 220K km2 below the next closest year.

That's amazing.  The forecast is straight insanity.

The day 10 image on the 00z euro is UNREAL.  WOULD BE TRULY EPIC.
That the models could even postulate this 10 days out is staggering.

It is absolutely insane.  If it happens, it's time to pray fervently for divine intervention for the ice.

OK...what is epic about the 10 day forecast? I see a temp forecast at 850 hpa. Google tells me this is generally about 1.5km above sea level, above the boundary layer.

If I open the GFS forecast and look what's doing in 10 days at sea level, I see the warm spots wherever this is open water in the forecast and all the ice covered areas are actually pretty mild at 0.0 - 1.0C.

https://climatereanalyzer.org/wx/fcst/#gfs.arc-lea.t2

If we're going to characterize things as "absolutely insane", maybe a little explanation of which feature of the forecast is insane is in order?
IDK, every part? Why is this denier being allowed to derail the melt thread with red herrings when we are XXXK below previous record minimum and all signs point to record-breaking conditions continuing both atmospherically and cryospherically.

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Re: The 2020 melting season
« Reply #2327 on: July 07, 2020, 10:11:31 AM »
Wow Sea ice extent is now 220K km2 below the next closest year.

That's amazing.  The forecast is straight insanity.

The day 10 image on the 00z euro is UNREAL.  WOULD BE TRULY EPIC.
That the models could even postulate this 10 days out is staggering.

It is absolutely insane.  If it happens, it's time to pray fervently for divine intervention for the ice.

Tonight's euro backed off of this solution to something more modest.

Never the less we have been tracking this since the mid to late 2000s.

And this has been an incredible run of weather when considering we haven't had a traditional dipole.

So inspite of not having those relentless compacting winds extent and area have still plummeted.

I expect them to slow some while melt will vigorously continue all over.

In August tho that thin ice with just vanish in many places.

Below is comparing SST anomalies between the 1st and 6th of July.

Huge growth in anomolous heat.

Also the current concentration.

We have seen vigorous clearing over the Atlantic side and look at how concentration just plummeted.

Then the current weather forecast for tomorrow.  Insane ridge.  Incredibly warm low level airmass rotating through the basin.   The euro has 3/4 of the basin sporting 5C 850mb temps.  That's just brutal .

And there is melt everywhere.

That's almost unheard of.

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a Desert Eagle that I call Big Pun
a two shot that I call Tupac
and a dirty pistol that love to crew hop
my TEC 9 Imma call T-Pain
my 3-8 snub Imma call Lil Wayne
machine gun named Missy so loud
it go e-e-e-e-ow e-e-e-e-e-e-blaow

Ktb

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Re: The 2020 melting season
« Reply #2328 on: July 07, 2020, 10:29:25 AM »
I don't care if the hot blob in the Laptev is from the Lena. You cannot ignore this hot water. 10.3 degC.
2+ degrees hotter in 6 days. Enjoying the high pressure and soaking up the sun.
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be cause

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Re: The 2020 melting season
« Reply #2329 on: July 07, 2020, 11:35:11 AM »
[quote author=Phoenix link=topic=3017.msg272304#msg272304 date=1594107461

OK...what is epic about the 10 day forecast? I see a temp forecast at 850 hpa. Google tells me this is generally about 1.5km above sea level, above the boundary layer.

If I open the GFS forecast and look what's doing in 10 days at sea level, I see the warm spots wherever this is open water in the forecast and all the ice covered areas are actually pretty mild ..

 ++++++++++++++++

It's not as if you haven't been helped to understand the relevance of using 850hpa temps before ..
[/quote]
The 850 hPa temperature is somewhere away from the ice. I'm not sure of the altitude, maybe someone with more knowledge than me can provide that.

But it is the temperature adjacent to the ice that is going to impact the ice, not the temperature 1,000 feet above sea level. For the benefit of the lurkers who are reading the thread, I think it's useful to kick the tires and questions some assumptions about the magnitude of the current events.

The heat coming into the Chukchi and ESS and the high winds pushing ice through Fram is quite significant and easily understandable and acceptable. No problem.

Maintaining heat over ice for a very long distance over ice and delivering it to the surface of much of the CAB where it can impact the ice in May is a completely differently animal. Skepticism of this is healthy from a scientific perspective.

Surface air temperatures over the ice are held close to a 0C maximum due to the latent heat of fusion of ice. This is quite apparent each year on the DMI 80N temperatures. For that reason, using something like the 850hPa temperature (or the less common, 925hPa value) is useful for assessing the relative heat mass over the ice. It's far from perfect, and temperature inversions, fog and such will add more complications, but much of the time in summer, 850hPa temperatures are more useful than surface temperatures.
« Last Edit: July 07, 2020, 11:42:44 AM by be cause »
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 + 2 = 2021 
 (phew)

Rubikscube

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Re: The 2020 melting season
« Reply #2330 on: July 07, 2020, 11:42:31 AM »
OK...what is epic about the 10 day forecast? I see a temp forecast at 850 hpa. Google tells me this is generally about 1.5km above sea level, above the boundary layer.

If I open the GFS forecast and look what's doing in 10 days at sea level, I see the warm spots wherever this is open water in the forecast and all the ice covered areas are actually pretty mild at 0.0 - 1.0C.

The surface temperature of melting ice is always going to be zero until the ice has melted and turned into water - that's thermodynamics - therefore surface temperatures from the ice are not going to tell you anything about how fast the ice is melting. That is why we use 850 hpa temps, because they are not affected by the ice and can tell you something about how much heat there is in the atmosphere. Yes, 850 hpa is 1.5 km above the surface and can in rare instances be misleading, but you'll need a very concrete reason to think so. Peolpe will even use 500 pha temps sometimes.

Regarding 2013 pole melt. 2013 had the exact opposite setup of what we have now. Back then a very persistent cyclone stuck around the north pole for so long that the ice dispersed to the point that it became visible in satellite images (for the same reason that the current anti-cyclone is compacting the ice). Fresh from the GAC-2012 a lot of people, myself included, thought this would spell doom for the ice, but as is usually the case, the cyclone kept the temperature low and actually helped preserve the ice (2013 was by all metrics a huge recovery from the year before). What we see in images right now is ice at the north pole melting in-situ. What we see in images from 2013 is ice at the north pole dispersing from wind action. 

Jontenoy

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Re: The 2020 melting season
« Reply #2331 on: July 07, 2020, 12:01:28 PM »
What is meant by the Euro in your discussions ?  It is not in the glossary

blumenkraft

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Re: The 2020 melting season
« Reply #2332 on: July 07, 2020, 12:05:17 PM »
The European weather forecast model ECMWF is meant by that, Jontenoy.

ArcticMelt2

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Re: The 2020 melting season
« Reply #2333 on: July 07, 2020, 12:37:42 PM »
So inspite of not having those relentless compacting winds extent and area have still plummeted.

I expect them to slow some while melt will vigorously continue all over.

I doubt the slowdown, now the peripheral seas are melting most actively, and there is a large excess of ice.

https://forum.arctic-sea-ice.net/index.php/topic,2975.msg271841.html#msg271841

NSIDC Area & Extent - some observations.

The contrast is even wider between the 7 Peripheral Seas and the 7 seas of the High Arctic.

High Arctic Extent has been lowest in the satellite record every day since June 18.
Peripheral Arctic Extent is currently 14th lowest

High Arctic Area has been in the lowest 4 in the satellite record every day since June 18, and is currently lowest.
Peripheral Arctic Area is currently 12th lowest

Obviously, up until now this has been very much to do with the Kara, Laptev & ESS. But in the last 2 days a new development (see next post if I am still awake).

oren

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Re: The 2020 melting season
« Reply #2334 on: July 07, 2020, 01:22:28 PM »
Asking good questions is well encouraged. It enables shy posters and lurkers to receive answers that otherwise they would have had to guess. Normally such questions should go in the questions thread or in subject-specific threads, but it is sometimes acceptable to post them in this thread as well, depending on context, and tone.
Asking repeat questions, in the main thread, in an adversarial tone, for which the answer has already been given and over which a consensus exists in the community, is ill-mannered and is seen as a way to preach rather than an innocent attempt to find answers.
Phoenix - your 850 hPa vs. surface temps question was an example of the latter.
Asking "Can someone explain what is insane with the forecast?" is perfectly acceptable and within context. I often wonder myself, though thanks to the efforts of knowledgeable posters I have learned some of the basics over the years. Had you stopped with that sentence, all would have been fine. But you didn't and are hereby warned, derailing this thread is not allowed and moderation will be swift. Note: If I had been up when the post was made I would have moved it elsewhere immediately, but it already garnered some responses so I will let it stay.

psymmo7

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Re: The 2020 melting season
« Reply #2335 on: July 07, 2020, 02:38:07 PM »
Asking good questions is well encouraged. It enables shy posters and lurkers to receive answers that otherwise they would have had to guess. Normally such questions should go in the questions thread or in subject-specific threads, but it is sometimes acceptable to post them in this thread as well, depending on context, and tone.
Asking repeat questions, in the main thread, in an adversarial tone, for which the answer has already been given and over which a consensus exists in the community, is ill-mannered and is seen as a way to preach rather than an innocent attempt to find answers.
Phoenix - your 850 hPa vs. surface temps question was an example of the latter.
Asking "Can someone explain what is insane with the forecast?" is perfectly acceptable and within context. I often wonder myself, though thanks to the efforts of knowledgeable posters I have learned some of the basics over the years. Had you stopped with that sentence, all would have been fine. But you didn't and are hereby warned, derailing this thread is not allowed and moderation will be swift. Note: If I had been up when the post was made I would have moved it elsewhere immediately, but it already garnered some responses so I will let it stay.

Well moderated Oren - Thank You!

Pagophilus

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Re: The 2020 melting season
« Reply #2336 on: July 07, 2020, 02:41:47 PM »
July 2-6.

2019.

Thanks as ever, Aluminium.  Visually extrapolating the ongoing rotation and inward-moving compaction of the polar ice pack, it looks like the passage on the Siberian side will be open in about 10 minutes...    :o 
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Pagophilus

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Re: The 2020 melting season
« Reply #2337 on: July 07, 2020, 03:06:21 PM »
I looked again at today's AMSR2 and at worldview.  The passage along the Siberian side is now only blocked at one, or maybe two points.  The ice, including fast ice, around Seveneraya Zemlya seems to be the main obstacle.  Maybe it is tight getting from the Laptev to the ESS as well.  Anyway, not a major indicator but surely an approaching milestone...

PS   Meltponds on the fast ice around S. Zemlya archipelago are changing from baby blue to gray, which I gather means they are draining. 
« Last Edit: July 07, 2020, 03:14:09 PM by Pagophilus »
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Paul

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Re: The 2020 melting season
« Reply #2338 on: July 07, 2020, 03:07:06 PM »


The debate is only about the incremental importance of surface temperatures which are forecast to decline in a few days.


This is a total straw man argument that no one but you is making, and the physics and thermodynamics do not support anything you say.

Instead, focus on something that really happened. In May, we had an unprecedented high that primed the ice for melting. You fought with Friv about it over and over. Friv was right. 

The high pressure system at the end of May helped precondition the ice, and that is why things we are seeing now are even worse.

There is a lot that can still happen this year. Maybe we get close to a record and maybe not, but quit shifting your target.

We will see what happens.

I disagree, what's causing the really low ice at the moment is the lack of fast ice in the ESS and the general thin ice that was there and the early opening of the Laptev which both was largely caused by the positive AO during winter as ice was not getting compacted in those regions.

The high pressure in May was impressive but imo because it was largely an Arctic high rather than a warm ridge, I don't think it caused that much damage although some minor melt ponds did occur admittedly.

Also the Siberian heat has been a major factor also, again because of wind direction and warmth, the ESS always looked vulnable and.it was a region for concern for me even before the melt season started. I must admit, I did not think the Laptev would open up as it did but when you got two regions at record low ice, no wonder extent is in a clear first place.

bluice

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Re: The 2020 melting season
« Reply #2339 on: July 07, 2020, 03:10:41 PM »
That ice is the remains of what used to be Gulf of Yana's fast ice. I doubt it lasts very long.

e: replying to Pagophilus's post above

blumenkraft

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Re: The 2020 melting season
« Reply #2340 on: July 07, 2020, 04:31:57 PM »
Very interesting visualisation!

Arctic Sea Ice Volume and Extent June 2020

Video at link >> https://www.reddit.com/r/dataisbeautiful/comments/hml6v8/arctic_sea_ice_volume_and_extent_june_2020_oc/

via /u/kevpluck

Pagophilus

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Re: The 2020 melting season
« Reply #2341 on: July 07, 2020, 04:43:25 PM »
So, as a non-expert, let me see if I have got this straight...  (and my mistakes, if corrected, may help illuminate matters for some other Frazilers)

The current anticyclone over the pole looks set to compact the ice and warm the Arctic generally.
 
a. It will compact the ice pack by 'pulling' ice inwards (really the Coriolis Effect), probably producing much more open water in the Chukchi, ESS and Laptev, and maybe in the Beaufort too.  This is already happening.

b. The extra areas of exposed seawater will then soak up a whole lot of near-maximum 24/7 Arctic insolation, warming their surface waters.  The warm water will remain at the surface because of its low density.  (Upwelling may also occur in places, bringing warm, saline water to the surface in places.)  All this seems probable, especially with the forecast clear skies.

d. Compaction will probably make for dramatic extent losses, but not necessarily in and of itself be terrible for the ice in terms of ice volume, since overall melting will be reduced when all the ice is together.

The rest is more speculative.  Anything can happen and has happened during melting seasons, producing far different results than anticipated at the time.  But here is a plausible scenario which I think many have been explicitly or implicitly discussing:

What would be a really bad sequel is, IF , after all this compaction of ice and warming of surrounding water has occurred, storms/cyclonic/dipole systems enter the Arctic region. Such events would not only bring in atmospheric heat, but also, more importantly, disperse the compacted ice into the newly warmed surrounding seas (Laptev, ESS etc).  In this situation, ice would melt rapidly, because the heat transfer from surrounding water is generally more destructive to ice than heat transfer from the air.  At this point, it might not matter much if the weather is cloudy or not.

I know there are many factors missing here (ocean currents etc) ... I welcome corrections if anyone has the time and look forward to learning more...
« Last Edit: July 07, 2020, 05:00:57 PM by Pagophilus »
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Juan C. García

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Re: The 2020 melting season
« Reply #2342 on: July 07, 2020, 05:05:54 PM »
Compaction is a strong extent killer and makes for big headlines. The more important questions at this stage are what happens with area - which also dropping fast, and especially volume/thickness - which one can only imagine is breaking some daily records.
I note that wind-induced Fram export has not started yet. The smaller Nares is already half empty and racing for the exit.
NSIDC Total Area as at 06-Jul-2020 (5 day trailing average) 6,142,884 KM2         
Sea ice area loss on this day 113 k, 8 k more than the 2010's average loss of 105 k         
         
- 2020 area is at position #1 in the satellite record.         
- 2020 Area is 522 k less than the 2010's average         
- 2020 Area is 1,193 k less than the 2000's average         
- 2020 Area is 324 k less than 2016         
- 2020 Area is 72 k less than 2019          
- 2020 Area is 101 k less than 2012

2020 is the lowest in extent (according to ADS JAXA by 221K km2 against 2016 [2nd lowest]) and it is also the lowest in area.
It doesn't look good at all!
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.

blumenkraft

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Re: The 2020 melting season
« Reply #2343 on: July 07, 2020, 05:08:34 PM »
d. Compaction will probably make for dramatic extent losses, but not necessarily in and of itself be terrible for the ice in terms of ice volume, since overall melting will be reduced when all the ice is together.

As you said, the exposed sea warmed up while the ice is gone and when the high pressure ends, the compaction reverses, pushing sea ice into now warmer waters, no? So this one is not a zero-sum game i think. Even more, if it's followed by a low.

KenB

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Re: The 2020 melting season
« Reply #2344 on: July 07, 2020, 05:35:59 PM »
Very interesting visualisation!

Arctic Sea Ice Volume and Extent June 2020

Video at link >> https://www.reddit.com/r/dataisbeautiful/comments/hml6v8/arctic_sea_ice_volume_and_extent_june_2020_oc/

via /u/kevpluck

That is indeed interesting.  One thing I noticed is that a line where y=x, which (loosely) represents the average ice depth being 1 meter, appears to now be reached during the part of the year when extent is around 8*10^6 and volume around 8*10^3, but perhaps not reached at the annual minimums (yet). 
"When the melt ponds drain apparent compaction goes up because the satellite sees ice, not water in ponds." - FOoW

igs

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Re: The 2020 melting season
« Reply #2345 on: July 07, 2020, 05:56:33 PM »
Last year wasn't 2nd lowest in extent. Not even close. Or am I wrong again?


That would have been easy to check before shooting away, the rest has been said.

Pagophilus

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Re: The 2020 melting season
« Reply #2346 on: July 07, 2020, 05:58:01 PM »
Ice cap edge melting apace north and west of FJL (at top right), probably representative of the entire Atlantic margin at this point.
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be cause

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Re: The 2020 melting season
« Reply #2347 on: July 07, 2020, 06:00:08 PM »
If you want to see what happens next if we have another week or two of anticyclone followed by whatever comes next take a look at Kara/ CAB . Browned ice is simply vanishing in situ. The streak from 79N 90E to 82N 90E ..@ 50,000 sqkm of 3 days ago has been collapsing .. especially where it has been pushed toward the island
  https://worldview.earthdata.nasa.gov/?v=815180.4200908248,944464.758704975,1164876.4200908248,1112656.758704975&p=arctic&t=2020-07-05-T15%3A10%3A34Z&l=Graticule(hidden),Coastlines(hidden),VIIRS_SNPP_Brightness_Temp_BandI5_Night(hidden,palette=green_1,min=220.7,max=240.2,squash=true),Reference_Labels(hidden),Reference_Features(hidden),VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor


 just play the next 2 days .. b.c.
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 + 2 = 2021 
 (phew)

Phoenix

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Re: The 2020 melting season
« Reply #2348 on: July 07, 2020, 06:04:11 PM »
The 5 day average NSIDC loss in the CAB on July 4 was 83.8k km2 or a total of 418k for the 5 days.

The current 5 day average through July 6th is 15.7k km2 or 88.5k km2 for the 5 days.

The difference in CAB area decline for the two days that left the 5 day average (June 30 and July 1) and the last two days that entered the 5 day average is 330k km2.

There are many potential explanations and I'm not going to try. Just an interesting bit of data to mull over.

Pagophilus

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Re: The 2020 melting season
« Reply #2349 on: July 07, 2020, 06:12:09 PM »
d. Compaction will probably make for dramatic extent losses, but not necessarily in and of itself be terrible for the ice in terms of ice volume, since overall melting will be reduced when all the ice is together.

As you said, the exposed sea warmed up while the ice is gone and when the high pressure ends, the compaction reverses, pushing sea ice into now warmer waters, no? So this one is not a zero-sum game i think. Even more, if it's followed by a low.

Yes. Although your zero-sum comment makes me think, and I now do have a reservation about this.  If just simple compaction occurs and surface area does not change, then net overall albedo should not change. (EDIT.  Useful to read Oren+Gero+Juan remarks in message 2342 at this point).   And therefore net absorption of solar radiation over the entire Arctic Ocean area should not change.  However, if the ice 'crinkles up' as it is compacted and therefore its surface area is decreased, then overall albedo would theoretically go down as more dark, open water is exposed.

One other factor... compaction is likely to push ice towards the pole.  Later dispersion, if it occurred, would take the ice to more southerly, warmer latitudes...

OK.  I will stop thinking 'aloud' and revealing my ignorance for the time being.  Wasn't it Twain who wrote that it is better to keep your mouth shut and have people think you a fool than open it up and remove all doubt?   
« Last Edit: July 07, 2020, 06:30:54 PM by Pagophilus »
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