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Glen Koehler

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Re: The 2020 melting season
« Reply #3250 on: July 20, 2020, 06:23:34 PM »
Here's the year-to-year comparison of the ASI (from AMSR2) maps for 19 July.
This year is unprecedented for the amount of ice cover lost by this date on the Russian side.

     The 2020 heat anomaly and high pressure systems so far this melt year are causing historically low-for-date Extent, with hard to understand not-1st place low Area loss (but I'm not trying to reignite that discussion), and low but not 1st place PIOMAS volume.  Given the conditions, even with the high Extent and Volume at start of season, I am surprised the ice is not in worse shape than it is.

     Looking at the deep purple areas of highest concentration and most likely to survive ice in the link posted by slow wing, July 19, 2020 looks surprisingly strong with a larger area of deep purple  high concentratoin ice than all but 3 of the 15 years displayed at
https://sites.google.com/site/arcticseaicegraphs/concentration-maps/sic0719

     The years with more deep purple being 2005, 2009, and 2017.   With 2020 showing LESS deep purple than 2006, 2007, 2008, 2010, 2011, 2012, 2014, 2015, 2016, and 2018.
 
      Expanding the comparison to deep + light purple gives a less dramatic comparison, but still does not make 2020 stand out like it seems it should.

     How can that be?  I am probably giving too much importance to an eyeball area estimate of deep purple, but this is one the main images we use to track Arctic ice status.  One unaccounted for factor is remaining melt momentum.  My guess is that 2020 at this point has more energy in the system and thinner, more vulnerable ice than prior years, thus greater losses in store for remainder of melt season than most earlier years (2012 excepted).  I also suspect that thickness losses are a hidden weakness in the 2020 ice.

     I think the High Arctic thickness graph posted by gerontocrat at https://forum.arctic-sea-ice.net/index.php/topic,119.msg275579.html#msg275579 says a lot about the trajectory of ASI decline in recent years.

     Compare the thickness for the 2000s vs. 2010s and now 2020.  I think that the effect of the 0.6 meter (25%) thickness reduction between 2000s and 2020 has more importance than the ratio implies.  That would be because there are important qualitative differences between 2.4 meter and 1.8 meter average ice thickness.  The thicker ice is older, has lower salinity and higher density, and thus higer "melt resistance".  If so, then the 25% reduction in thickness could represent a 33% (just to have a number) decrease in melt resistance. 

     (2017 is an exception somewhat, but it was coming off of high melt year in 2016 followed by an extremely warm winter.  By my theory then, 2017 with its thin ice should have been another near record low September Extent and Volume.  2017 ended up above the straight-line trend for Extent, and just below the trend for Volume.  But the thickness factor does not have to overwhelm melt season weather -- which 2017 apparently lacked -- in order to be true as an important influence).

     If this conjecture is correct, then adding the qualitative effect of thicness reduction to the already low Extent/Area/Volume values puts 2020 even lower compared to all prior years.

     I'll go farther out on a limb to propose that there is a break point around 2 meters ice thickness.  That is about the amount that can freeze in one winter or melt out in a melt season.  I have to wonder if going below 2 meters thickness initiates a nonlinear accelerated reduction in melt resistance.  It certainly reflects the shfit from MYI to FYI which we all agree has been one of the big story lines since 2007.  And speaking of 2007, I think that it, not 2012, is the epic year that should get more attention in terms of understanding the effects of melt season weather and the modern progession of ASI decline.  No disrespect to 2012, but 2007 was a knockout punch that came out of nowhere.  The MYI ice loss that year set the stage for all that has happened since.
« Last Edit: July 21, 2020, 05:49:15 AM by Glen Koehler »

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Re: The 2020 melting season
« Reply #3251 on: July 20, 2020, 06:33:38 PM »
'The crazy heat on the Siberian side' continues .. > 32'C forecast for the Siberian arctic for the next 5 days with high night temps as well . The warmth and rain that originally threatened to sweep across the basin are now being deflected toward Bering and Alaska . There will be a lot of warm wet ice again for a few days . b.c.
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 + 2 = 2021 
 (phew)

Pagophilus

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Re: The 2020 melting season
« Reply #3252 on: July 20, 2020, 06:39:15 PM »
...a graph of the CAB's compaction shows it to be in the middle of the pack, historically.

This is why I'm with Friv; IDK why a few folks are saying it's "compact". It's really quite average. Gero posted a graph a few days back illustrating this.

This from Yale Climate Connection re. compaction

"It’s not just the barrage of sun-driven melt that allows high pressure in early summer to cut into sea ice extent. As air flows clockwise around the high, the ocean and ice surface are pushed toward the right of the wind at any given spot. The result? The ice is packed into a smaller, more concentrated area, which allows sunlight to warm the newly exposed waters."

https://www.yaleclimateconnections.org/2020/07/baked-by-midsummer-sun-arctic-sea-ice-could-face-worst-losses-on-record/   my bolding

It is also worth noting that if there is a huge amount of insolation-induced melting of the ice pack at the same time (and there has been), then the concentration of the compacting icepack can remain the same or actually drop. 

In other words, compaction in the sense of reduction of ice extent can occur, but melting can result in drops in concentration of that compacted ice.
« Last Edit: July 20, 2020, 08:41:37 PM by Pagophilus »
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bill kapra

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Re: The 2020 melting season
« Reply #3253 on: July 20, 2020, 06:49:02 PM »

     I'll go one step farther out on a limb and propose that there is a break point around 2 meters ice thickness.  That is about the amount that can freeze in one winter or melt out in a melt season.  I have to wonder if going below 2 meters thickness indicates a shift to less melt resistance.  It certainly reflects the shfit from MYI to FYI which we all agree has been one of the big story lines since 2007.  And speaking of 2007, I think that it, not 2012, is the epic year that should get more attention in terms of understanding the effects of melt season weather and the modern progession of ASI decline.  No disresect to 2012, but 2007 was a knock out punch that came out of nowhere.  The MYI ice loss that year set the stage for all that has happened since.

That seems reasonable... that we could assess annual melt midseason and compare to average thickness based on the nonlinearity you point out.

But, with local variability of ice thickness, how valuable would such a measure be? And, has it been built for 2020?

jdallen

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Re: The 2020 melting season
« Reply #3254 on: July 20, 2020, 06:52:13 PM »
>snippage>This explains why area has not kept up with extent loss in terms of the rankings of 2020 and other strong melt seasons.
<snippage>

Thanks FooW.  This is the first explanation for area's persistent lagging extent that makes full sense to me.   

(my bolding on your comment).
From Gerontocrat on the area/extent thread - today's numbers:


- 2020 area is at position #3 in the satellite record.         
- 2020 Area is 403 k less than the 2010's average         
- 2020 Area is 1,213 k less than the 2000's average         
- 2020 Area is 209 k less than 2016         
- 2020 Area is 95 k more than 2019         
- 2020 Area is 89 k more than 2012
   

Area *may* have been lagging, but it really isn't any longer.  When you consider confidence intervals, 2020, 2019 & 2012 - the years with the lowest area - are currently in a dead heat in the race to the bottom.  The differences between them amount to less than 1 days melt at current rates.
« Last Edit: July 20, 2020, 06:58:00 PM by jdallen »
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Pagophilus

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Re: The 2020 melting season
« Reply #3255 on: July 20, 2020, 06:57:46 PM »
>snippage>This explains why area has not kept up with extent loss in terms of the rankings of 2020 and other strong melt seasons.
<snippage>

Thanks FooW.  This is the first explanation for area's persistent lagging extent that makes full sense to me.   

(my bolding on your comment).
From Gerontocrat on the area/extent thread:


- 2020 area is at position #3 in the satellite record.         
- 2020 Area is 403 k less than the 2010's average         
- 2020 Area is 1,213 k less than the 2000's average         
- 2020 Area is 209 k less than 2016         
- 2020 Area is 95 k more than 2019         
- 2020 Area is 89 k more than 2012
   

Area *may* have been lagging, but it really isn't any longer.  When you consider confidence intervals, 2020, 2019 & 2012 - the years with the lowest area - are currently in a dead heat in the race to the bottom.  The differences between them amount to less than 1 days melt at current rates.
Thanks for this Gerontocrat, even though it is really sobering news. 
Maybe the Arctic sea ice is running low on large draining meltponds.  That would not bode well for central ice pack integrity...   :o
« Last Edit: July 20, 2020, 07:09:49 PM by Pagophilus »
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Re: The 2020 melting season
« Reply #3256 on: July 20, 2020, 07:09:58 PM »
'twill be interesting to see if all the coming rain (from China ) will cause a new surge in melt ponds or show that that phase is over ... b.c.
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 + 2 = 2021 
 (phew)

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Re: The 2020 melting season
« Reply #3257 on: July 20, 2020, 08:11:52 PM »

Unless the ESS/Chuchki/CAB start melting out insitu like the NORTHERN LAPTEV

That's about what I suspect to happen while I wouldn't go that far to say that there won't be any slow down but it may be minor (less than expected) and eventuelly very shortlived.


Afte there are huge amounts of ice in the Beaufort (amount) ESS/Lapteve (Condition) and Greenland Sea ( location ) with a potential to desingrated and with the winds it will inevitably happen.

FishOutofWater

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Re: The 2020 melting season
« Reply #3258 on: July 20, 2020, 08:18:04 PM »
Ice on the Siberian side continues to be toasted, but the Hycom model has been already forecasting thick ice in the CAA to start moving down towards the main channel into oblivion. As has been noted upthread, there is visual evidence of ice cracking up further and further into the blocked region of the main channel. Warm southerly winds that put tension on ice to move from the CAA's passages into the Arctic ocean are one very effective way of getting the "garlic press" moving. Once the ice dams on the Arctic side are broken, ice will move with the winds, currents and tides.

The polar high is breaking down in a way that is not good for the ice on the CAA side. Moreover, flow through the garlic press will lead to less ice exported into the Beaufort sea which will improve chances of ice melting out there. That's what the Hycom model is forecasting. Thinning Beaufort ice and less imported ice.

The heat is on in the CAA and may get worse with the developing weather.


werther

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Re: The 2020 melting season
« Reply #3259 on: July 20, 2020, 09:06:26 PM »
Area as well as PIOMAS volume is flawed during summer. The ice isn’t ‘holding up well’. Just look at Worldview at a well visible spot some 1500 km NW of Prince Patrick Island. That used to be part of ‘the safe structured haven’ of about 1,8 Mkm2 pack ice. If situated on the rim, I’d call the visible structure ‘goodbye waves’.

Bremen Uni’s colours in this phase of the melt season doesn’t reflect the situation in a reliable fashion. It isn’t completely wrong too. But it needs interpretation. That is why I studied the MODIS tiles in detail for years. Worldview is a means too, but, hélas, doesn’t fit my original method (so I gave up in ’17).

A large part in the creation of the current situation is terrible conditions for sea ice survival on the Siberian sector, rapid melt-out of Hudson and Baffin Bay and serious pre-conditioning over the Arctic during May. What saves the day is ‘winter power’ over Beaufort and CAA last winter.

Hard core warming is all over the place under the 415 ppm CO2 cover and even higher total greenhouse gas content. In thirteen years (since '07) the remaining time lapse to prevent a major climate reset has passed. And with it, the small chance to prevent a BOE. It could happen any year now. In ’07, strong compaction saved a lot of volume. In ’12, enough MYI remained to withstand a complete collapse in the Laptev sector. Those advantages now have faded out. The survival of pack ice in the Arctic is completely in the hands of weather. A GAC could be devastating, an August dipole could, whatever. Don’t pay to much attention to DMI-2 meter temps N of 80 degrees. Those reflect melt conditions. Look for temps on 950 MB and large swirls in the jet stream. It is on the rim of the Rossby-waves that Nemesis for the ice will ride…

Lord M Vader

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Re: The 2020 melting season
« Reply #3260 on: July 20, 2020, 09:41:13 PM »
I hope it is just my eyes, but look at the ice in the Laptev sector at around 87-88°N and you can see that it has started to get brownish. :o This is just sooo bad!

uniquorn

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Re: The 2020 melting season
« Reply #3261 on: July 20, 2020, 09:44:01 PM »
A casual look through the iabp table is a bit like playing 'find objects'
Anyway, we have some new (and old) buoys. Will have to resolve a drift speed problem but here is the first draft. click to run
I suppose some area calcs might resolve the compaction issue but I'm not going there
« Last Edit: July 20, 2020, 10:36:09 PM by uniquorn »

VeliAlbertKallio

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Re: The 2020 melting season
« Reply #3262 on: July 20, 2020, 09:46:56 PM »
BBC and Nature Climate Change today: "Ignorantia stupor hoc est ianua"

One of the most misleading articles has appeared in BBC minimising the risks of the Arctic sea ice loss. Far too many people fail to understand that the short, extreme periods of weather and sea ice melting are dangerous to biological life. On the other hand, glaciers suffer from tiny rises in temperature averages over long time. Only one or two days of extreme heat shock can kill plants and animals extinct whether it is frost or heat shock if they are not adapted to such temperatures. I bet that just one or two summer seasons without Arctic sea ice will kill all polar bears by starvation: therefore citing averages "becoming critical for polar bear survival" around year 2100 is seriously faulty argument. Some GCMs already modelled that this summer leads to 'sticky 2020/2021 winter' followed by 2021 another melt that causes so much delay in the onset of 2021/2022 winter that the jet streams may push depression systems tracks to far south Portugal - Morocco line (whereas these used to be north of Britain). https://www.bbc.co.uk/news/science-environment-53474445  :'(

(I've received support from Professor Sir Ghillean Prance, FRS and others that the argument is faulty, circumstantial evidence is high: adverse conditions to starve bears are likely to occur before 2100.)
« Last Edit: July 22, 2020, 08:45:05 AM by VeliAlbertKallio »
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Yuha

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Re: The 2020 melting season
« Reply #3263 on: July 20, 2020, 10:04:31 PM »
I think the discrepancy between extent and area is explained by two factors.

One is the melt pond drainage mentioned by Lodger and FOW above.

The other is lack of dispersal. On many years, large regions of the ice pack have started to disperse in July but this year the GAAC has prevented most of that. The image below is an example of strong dispersal from July 19, 2016.

Pagophilus

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Re: The 2020 melting season
« Reply #3264 on: July 20, 2020, 10:41:39 PM »
Very warm winds coming after the remnants of the ESS ice (and other bodies of solid water)
Nullschool forecast for July 22
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Re: The 2020 melting season
« Reply #3265 on: July 21, 2020, 12:04:50 AM »
I think the discrepancy between extent and area is explained by two factors.

One is the melt pond drainage mentioned by Lodger and FOW above.

The other is lack of dispersal.

We are getting sooo sidetracked on a very basic issue.  The microwaves that are used to measure the ice are very good at distinguishing between solid ice and liquid water in the winter.

They are not very good in the summer when fog and wet clouds and wet ice and dry ice and melt ponds and ect ... are involved.

Area is not easy to interpret in the summer because of the effects on how the microwaves “see” wetness.  Because of that, we use extent for the official data.

That is not great either, because it could have a margin of error as much as 85% in each measured grid. If I remember correctly, NSIDC uses grids of 25km x 25km so that number could be quite significant.

But, we don’t need to get bogged down in the problems with the microwaves and how they measure if we keep an eye on the visible spectrum on worldview.

At the end of the day, this year might or might not break some records regarding extent, area, or PIOMAS volume.  But we can see how bad it is by using our own eyes and thinking about the two most important factors 1) albedo and 2) latent heat of fusion.

Michael Hauber

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Re: The 2020 melting season
« Reply #3266 on: July 21, 2020, 12:28:30 AM »


now  Most of the ice pack is solid

2012 Most of the ice pack is not solid.
Climate change:  Prepare for the worst, hope for the best, expect the middle.

BornFromTheVoid

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Re: The 2020 melting season
« Reply #3267 on: July 21, 2020, 12:30:43 AM »
ECM want to send some heat over the remaining thick ice at the end of the week. 2020 is relentless.
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

Rod

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Re: The 2020 melting season
« Reply #3268 on: July 21, 2020, 12:35:59 AM »
Michael,

That is a good topic to debate! We can argue about how much surface melting has occurred this year vs. 2012 because of the compaction, and argue about what might happen if a GAC hits the ice this year like in 2012. 

Personally, I think the ice is way more fucked in 2020 than in 2012, but I could certainly be wrong.

Paul

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Re: The 2020 melting season
« Reply #3269 on: July 21, 2020, 01:37:03 AM »
Michael,

That is a good topic to debate! We can argue about how much surface melting has occurred this year vs. 2012 because of the compaction, and argue about what might happen if a GAC hits the ice this year like in 2012. 

Personally, I think the ice is way more fucked in 2020 than in 2012, but I could certainly be wrong.

I would imagine a deep low would not affect the ice in a negative way(e.g melting) but it would cause huge dispersion which could then lead to negative Impacts on the ice.

I said it before and its only my opinion, a diverse ice pack is more likely to make its impact on the 2nd half of the melt season where SSTS and even temperatures are at their highest and its easier for the ice to be nibbled away whilst in theory a more compact ice cover should be more resilient especially the closer to the pole you go. 2018 is a fairly good example of this, the ice pack was quite spread out on the Pacific side of the basin leaving a fairly healthy extent amount however the Pacific side between now and September collapsed badly as the Beaufort was thin ice to start off with and showed heavy dispersion right now and the thicker Siberian ice was alot more resilient but even that ice more or less melted away by September. At least then the Siberian side could survive a few heat spells unlike this year's Siberian ice!

Of course with this year especially there is some caveats to this supposed compaction. Ice thicknesses even looking from above don't look all that great so that compact looking ice could easily look alot more diffused in 4 weeks time. SSTS are very high in the Laptev, this could cause bottom melt and have the ice edge heading even further northwards and lastly, we are so low, even any supposed compaction may not prevent a record low by September but i don't think that is a big thing because the current extent in anycase is newsworthy enough.

At.this stage imo, Im not too convinced we will be at record lows come September but I think it will be a miracle if we finish above 4 million. I think we are going to be comfortably 2nd lowest and a ice shape similar to 2007 but without the outstretched ice towards Laptev and the Atlantic front closer to the pole. How much Beaufort ice survives will also play a role but whilst it will try and hold on, I don't think it's going to prevent this year's extent finish any better than 2nd lowest.

jdallen

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FishOutofWater

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Re: The 2020 melting season
« Reply #3271 on: July 21, 2020, 01:53:39 AM »
Note how the buoys on the coastal sides of the Beaufort sea move much longer distances than buoys in the central Arctic and the center of the Beaufort gyre. I'm pretty confident that the faster movement on the margins leads to divergence and the upward mixing of water from below between ice floes. Unless the floes are thick, they will melt out under present temperatures.

We have discussed how the brown ice may have algae. There's also high water content ice at that's melting out that I was familiar with when I lived in New Hampshire. Slush has a yellow brown color, and I don't mean the snow that's where dogs have been walking. I think we are seeing that brownish slush color now very close to the pole on the Laptev side. I agree we should make good use of what we see in the visible spectrum.

Obviously, high water content ice is going to cause satellite microwave sensors to some issues.

igs

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Re: The 2020 melting season
« Reply #3272 on: July 21, 2020, 02:03:57 AM »

now  Most of the ice pack is solid

2012 Most of the ice pack is not solid.

It's easy to be not solid being spread over several 100'000 km2 more.

The now open water in more southern latitudes will take on heat much longer than eventual leads up north where the remaining ice is and once the ice will disperse into those waters it will be gone for sure.

After all we're lucky if much of the ice won't melt in situ but a dispersion in August will do the job for sure.

Also I do not find it perfectly ok to make statements that mean to say something unpopular or controverse without saying it properly. Normally this kind of posts make all kinds of disruptive discussion brake loose.

Michael Hauber

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Re: The 2020 melting season
« Reply #3273 on: July 21, 2020, 03:05:44 AM »


now  Most of the ice pack is solid

2012 Most of the ice pack is not solid.
Looking at the Atlantic front, and eastern stretches of the Beaufort, I'm not sure I can agree.

More solid?  Maybe.  Most?  Questionable.

https://worldview.earthdata.nasa.gov/?v=-2460326.7085299785,-376688.3961351371,-1061542.7085299785,263311.6038648629&p=arctic&t=2020-07-20-T22%3A15%3A30Z&l=Reference_Labels(hidden),Reference_Features(hidden),Coastlines,VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor

Beaufort is certainly the standout with quite a  bit of ice that is not compact, and some cracking/minor dispersion spreading quite a long way towards the core of the Arctic.  I do think that the exception of Beaufort, the rubble fields in Chukchi and the ESS remnants, and the fringe along Atlantic are small enough that using the words 'most of the Arctic' to describe everything else is quite appropriate. 
Climate change:  Prepare for the worst, hope for the best, expect the middle.

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Re: The 2020 melting season
« Reply #3274 on: July 21, 2020, 03:28:24 AM »
Seems like this might be important...

Pagophilus

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Re: The 2020 melting season
« Reply #3275 on: July 21, 2020, 03:45:20 AM »
Seems like this might be important...
And this also from Zach Labe.  Just another way of seeing things...
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oren

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Re: The 2020 melting season
« Reply #3276 on: July 21, 2020, 03:48:40 AM »
The CAB may be more compacted, but that is not thanks to high area, it's simply a result of lower extent. While we do not know the UH area for 2012 for this date, one can surmise the 2D situation was quite similar, and not something that can be considered good. The big question is if August will bring CAB area crashes as it did in 2012 and 2016. Considering the roasting under clear skies in the past few weeks, I expect the answer is yes.

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Re: The 2020 melting season
« Reply #3277 on: July 21, 2020, 03:48:54 AM »
Michael,
<snip>
 We can argue about how much surface melting has occurred this year vs. 2012 because of the compaction.......  <snip>

What compaction? I don't see any compaction to be worth mentioning. I am using a large screen high def laptop. I don't see it. Can those that keep bringing up compaction show some images or other proof? Please.

"....and the appointed time came for God to bring to ruin those ruining the earth." Revelation 11:18.

Pagophilus

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Re: The 2020 melting season
« Reply #3278 on: July 21, 2020, 04:47:51 AM »
Ellesmere Island crack, July 14-20. 

Watch out, I've just learned how to make gifs.  Hope this one is not over the limit.  All critiques welcome re. timing, image size, alignment, dumb choice of subject, etc...     :)

Role of icepack rotation in producing the crack seems evident to me.

Also, some of the arms of those sets of ?fiords? at center bottom left are melting out almost like magic.   :o
« Last Edit: July 21, 2020, 05:04:49 AM by Pagophilus »
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Thomas Barlow

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Re: The 2020 melting season
« Reply #3279 on: July 21, 2020, 04:56:00 AM »
.

UCMiami

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Re: The 2020 melting season
« Reply #3280 on: July 21, 2020, 04:56:13 AM »
Seems like this might be important...
And this also from Zach Labe.  Just another way of seeing things...
What is interesting to me is that this wide a separation between extent and previous years in July is unique - it has gotten to a full five plus day lead on any other year and even in previous anomalous years in the 2010s that just hasn't happened in July.

This is not just an outlier year - it is basically doubling the differential of any of the other years.

oren

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Re: The 2020 melting season
« Reply #3281 on: July 21, 2020, 05:22:15 AM »
Watch out, I've just learned how to make gifs.  Hope this one is not over the limit.  All critiques welcome re. timing, image size, alignment, dumb choice of subject, etc...     :)
Congratulations. The secret "video camera" button on Worldview can make these gifs automatically, so much easier (took me years to realize this).
But in any case best to upload animations to https://ezgif.com/optimize and save a smaller gif as a result.

Frivolousz21

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Re: The 2020 melting season
« Reply #3282 on: July 21, 2020, 06:10:54 AM »
Here's the year-to-year comparison of the ASI (from AMSR2) maps for 19 July.
This year is unprecedented for the amount of ice cover lost by this date on the Russian side.

     The 2020 heat anomaly and high pressure systems so far this melt year are causing historically low-for-date Extent, with hard to understand not-1st place low Area loss (but I'm not trying to reignite that discussion), and low but not 1st place PIOMAS volume.  Given the conditions, even with the high Extent and Volume at start of season, I am surprised the ice is not in worse shape than it is.

     Looking at the deep purple areas of highest concentration and most likely to survive ice in the link posted by slow wing, July 19, 2020 looks surprisingly strong with a larger area of deep purple  high concentratoin ice than all but 3 of the 15 years displayed at
https://sites.google.com/site/arcticseaicegraphs/concentration-maps/sic0719

     The years with more deep purple being 2005, 2009, and 2017.   With 2020 showing LESS deep purple than 2006, 2007, 2008, 2010, 2011, 2012, 2014, 2015, 2016, and 2018.
 
      Expanding the comparison to deep + light purple gives a less dramatic comparison, but still does not make 2020 stand out like it seems it should.

     How can that be?  I am probably giving too much importance to an eyeball area estimate of deep purple, but this is one the main images we use to track Arctic ice status.  One unaccounted for factor is remaining melt momentum.  My guess is that 2020 at this point has more energy in the system and thinner, more vulnerable ice than prior years, thus greater losses in store for remainder of melt season than most earlier years (2012 excepted).  I also suspect that thickness losses are a hidden weakness in the 2020 ice.

     I think the High Arctic thickness graph posted by gerontocrat at https://forum.arctic-sea-ice.net/index.php/topic,119.msg275579.html#msg275579 says a lot about the trajectory of ASI decline in recent years.

     Compare the thickness for the 2000s vs. 2010s and now 2020.  I think that the effect of the 0.6 meter (25%) thickness reduction between 2000s and 2020 has more importance than the ratio implies.  That would be because there are important qualitative differences between 2.4 meter and 1.8 meter average ice thickness.  The thicker ice is older, has lower salinity and higher density, and thus higer "melt resistance".  If so, then the 25% reduction in thickness could represent a 33% (just to have a number) decrease in melt resistance. 

     (2017 is an exception somewhat, but it was coming off of high melt year in 2016 followed by an extremely warm winter.  By my theory then, 2017 with its thin ice should have been another near record low September Extent and Volume.  2017 ended up above the straight-line trend for Extent, and just below the trend for Volume.  But the thickness factor does not have to overwhelm melt season weather -- which 2017 apparently lacked -- in order to be true as an important influence).

     If this conjecture is correct, then adding the qualitative effect of thicness reduction to the already low Extent/Area/Volume values puts 2020 even lower compared to all prior years.

     I'll go farther out on a limb to propose that there is a break point around 2 meters ice thickness.  That is about the amount that can freeze in one winter or melt out in a melt season.  I have to wonder if going below 2 meters thickness initiates a nonlinear accelerated reduction in melt resistance.  It certainly reflects the shfit from MYI to FYI which we all agree has been one of the big story lines since 2007.  And speaking of 2007, I think that it, not 2012, is the epic year that should get more attention in terms of understanding the effects of melt season weather and the modern progession of ASI decline.  No disrespect to 2012, but 2007 was a knockout punch that came out of nowhere.  The MYI ice loss that year set the stage for all that has happened since.

That can be because the dark purple area  are covered in deep fog. 

It has been discussed a million times on here that Bremen concentration is highly affected by clouds, vapor, fog.
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Re: The 2020 melting season
« Reply #3283 on: July 21, 2020, 06:13:00 AM »
Another century break:


[ADS NIPR VISHOP (JAXA)] Arctic Sea Ice Extent.

July 20th, 2020:
     6,333,877 km2, a century drop of -114,342 km2.
     2020 is the lowest on record.
     Highlighted 2020 & the 4 years with a daily lowest min in Sept. (2012, 2019, 2016 & 2007).
     In the graph are today's 10 lowest years.
     Source: https://ads.nipr.ac.jp/vishop/#/extent


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Re: The 2020 melting season
« Reply #3284 on: July 21, 2020, 06:24:08 AM »
After the NSIDC results today, I was *sure* that the JAXA would be sub-century today, but I guess that's not the case once again. I wonder how many more days it will be able to sustain near-this level of extent reduction?

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Re: The 2020 melting season
« Reply #3285 on: July 21, 2020, 06:35:57 AM »
After the NSIDC results today, I was *sure* that the JAXA would be sub-century today, but I guess that's not the case once again. I wonder how many more days it will be able to sustain near-this level of extent reduction?

Looks like there is a bit more to go before things really level off.  Might be looking at it wrong but looks some of the remaining ESS ice is amidst rising SSTs, given the physics of ice melt that implies it is on its last legs there.  Speaking of high SSTs, are there actually pockets of 10C WATER in that coastal Beaufort strip!  Was watching the time sequence of ice from the Beaufort rotating into that strip and it all seemed to evaporate as soon as it crosses that line that has been open water for weeks now.  Seems like very warm SSTs encroaching in the Greenland Sea also and popping up in the Laptev bite to a lesser degree.

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Re: The 2020 melting season
« Reply #3286 on: July 21, 2020, 06:46:13 AM »


now  Most of the ice pack is solid

2012 Most of the ice pack is not solid.
Looking at the Atlantic front, and eastern stretches of the Beaufort, I'm not sure I can agree.

More solid?  Maybe.  Most?  Questionable.

https://worldview.earthdata.nasa.gov/?v=-2460326.7085299785,-376688.3961351371,-1061542.7085299785,263311.6038648629&p=arctic&t=2020-07-20-T22%3A15%3A30Z&l=Reference_Labels(hidden),Reference_Features(hidden),Coastlines,VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor

Beaufort is certainly the standout with quite a  bit of ice that is not compact, and some cracking/minor dispersion spreading quite a long way towards the core of the Arctic.  I do think that the exception of Beaufort, the rubble fields in Chukchi and the ESS remnants, and the fringe along Atlantic are small enough that using the words 'most of the Arctic' to describe everything else is quite appropriate.

The problem with the Beaufort is it ends up with a lot of dispersal every year but always somehow manages to entrain more ice and hang on.  Until it doesn’t, but that is a bit unpredictable through my eyes.

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Re: The 2020 melting season
« Reply #3287 on: July 21, 2020, 06:49:02 AM »
There is 825,000km2 less ice than 2012 right now. 


That makes it really hard to compare 20 vs 12.

That means 2020 has open water the size  of TEXAS plus another 135,000km2 over 2012.


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Re: The 2020 melting season
« Reply #3288 on: July 21, 2020, 07:21:00 AM »
Here's the year-to-year comparison of the ASI (from AMSR2) maps for 19 July.
This year is unprecedented for the amount of ice cover lost by this date on the Russian side.
     I'll go farther out on a limb to propose that there is a break point around 2 meters ice thickness.  That is about the amount that can freeze in one winter or melt out in a melt season.  I have to wonder if going below 2 meters thickness initiates a nonlinear accelerated reduction in melt resistance.  It certainly reflects the shfit from MYI to FYI which we all agree has been one of the big story lines since 2007.  And speaking of 2007, I think that it, not 2012, is the epic year that should get more attention in terms of understanding the effects of melt season weather and the modern progession of ASI decline.  No disrespect to 2012, but 2007 was a knockout punch that came out of nowhere.  The MYI ice loss that year set the stage for all that has happened since.

That can be because the dark purple area  are covered in deep fog. 

It has been discussed a million times on here that Bremen concentration is highly affected by clouds, vapor, fog.

I definitely agree with the position that 2007 was the tipping point year and 2012 was more of an outlier.  After 2007 the ice has never returned to the pre-2007 patterns it seems to me.  That being said maybe 2020 is a tipping point, just look how enormous the gap in extent is right now this year vs next lowest and then look at the gaps in each next lowest.  And we are seeing this when insolation is high and less cloudiness than usual.  All that extra open water has to have already captured a gargantuan amount of heat beyond what any other season has experienced during the period since 2020 plunged into the record book.

Regarding Bremen concentration I personally am a fan, have had to learn how to read it and not make too much of sudden anomalous concentration changes.  When I see open water mixed with color change or color change that persists and evolves in a logical fashion across multiple days if you can see past the noise then I consider that it is meaningful change.

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Re: The 2020 melting season
« Reply #3289 on: July 21, 2020, 08:28:46 AM »
July 16-20.

2019.

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Re: The 2020 melting season
« Reply #3290 on: July 21, 2020, 08:33:59 AM »
August always has at least 1.5m of melt and that's being really conservative and September always 100000. That's 1.6million. Also what's left to lose in July? A million?

Let's say the least we can lose is 2.5million now. That means 3.8million is the HIGHEST the Jaxa can be with a moderate melt until the end. 2nd is the BEST it can get but straight first still possible.

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Re: The 2020 melting season
« Reply #3291 on: July 21, 2020, 09:25:25 AM »
My guess is the compaction has mostly been plates of fresh ice pushed upwards by older floes, increasing the surface area of ice subect to the warm air enormously, and pressing the floes deeper into the ocean. A high of around 1030 is by itself going to push 20cm of water away from it's epicenter, before accounting for mass accumulation of the ice, that's moving to cross Lomonosov and in it's wake comes the inflow from the Pacific, in turn that defines the rotation of Beaufort and now it looks set that the tides in Amundsen gulf will force a flow across to Barrow. In it's turn that draws in more Atl. water past the CAA coast, so it's likely we'll see a cleavage occur where a melt/freeze undercurrent of both Atl. and Pac. waters pass from ESS towards Fram and a cw circulation of Beaufort introduces ice to the incoming Atl. waters somewhere off Prince Patrick is., and free to tumble the floes get slaughtered.

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Re: The 2020 melting season
« Reply #3292 on: July 21, 2020, 09:52:09 AM »
In this sector open water area today roughly about 50,000 km². And winds about 6 - 8 m/s continue today, tomorrow.

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Re: The 2020 melting season
« Reply #3293 on: July 21, 2020, 11:38:34 AM »
From Gerontocrat on the area/extent thread:


- 2020 area is at position #3 in the satellite record.         
- 2020 Area is 403 k less than the 2010's average         
- 2020 Area is 1,213 k less than the 2000's average         
- 2020 Area is 209 k less than 2016         
- 2020 Area is 95 k more than 2019         
- 2020 Area is 89 k more than 2012
   

Area *may* have been lagging, but it really isn't any longer.  When you consider confidence intervals, 2020, 2019 & 2012 - the years with the lowest area - are currently in a dead heat in the race to the bottom.  The differences between them amount to less than 1 days melt at current rates.
Thanks for this Gerontocrat, even though it is really sobering news. 
Maybe the Arctic sea ice is running low on large draining meltponds.  That would not bode well for central ice pack integrity...   :o


In some past years, not only melting ponds have been observed in the Central Arctic, but a lot of open water. See, for example, pictures from 2010, 2013, 2016. Now the ice, on the contrary, is strongly compressed, and is protected from strong bottom melting. So, IMHO, the ice can be saved this year.

Now the thin ice is almost over, and the ice in the Central Arctic looks cohesive and protected. Moreover, there are no strong cyclones in the forecasts.

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Re: The 2020 melting season
« Reply #3294 on: July 21, 2020, 12:34:48 PM »
I know a lot of the discussion has been about how different this season has been with the increased melt. But how does it compare on the overall trend?
Looking at volume trends I think this year will struggle to be on or below the trendlines.

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Re: The 2020 melting season
« Reply #3295 on: July 21, 2020, 12:41:20 PM »
There is 825,000km2 less ice than 2012 right now. 


That makes it really hard to compare 20 vs 12.

That means 2020 has open water the size  of TEXAS plus another 135,000km2 over 2012.

We know the losses over the GAC in 2012 and if 2020 has those losses (nearly?) 'in the bank' prior to the period those loses occurred in Aug then will we be looking favourite to set a new record low?

But then what if 2020 threw in its own GAC over Aug????
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Re: The 2020 melting season
« Reply #3296 on: July 21, 2020, 01:04:10 PM »
I had a look at SST anomalies change in July from http://ocean.dmi.dk/satellite/index.uk.php.

While Baffin Bay, Kara & Laptev seas show spectacular SST increases this month, the same cnnot be said for the Bering Chukchi seas, especially compared with 2019.

gif attached -- July 1 & July 20.
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Re: The 2020 melting season
« Reply #3297 on: July 21, 2020, 01:17:21 PM »
There is 825,000km2 less ice than 2012 right now. 


That makes it really hard to compare 20 vs 12.

That means 2020 has open water the size  of TEXAS plus another 135,000km2 over 2012.

We know the losses over the GAC in 2012 and if 2020 has those losses (nearly?) 'in the bank' prior to the period those loses occurred in Aug then will we be looking favourite to set a new record low?

But then what if 2020 threw in its own GAC over Aug????
If remaining sea ice melt (JAXA sea ice extent) is just 4.3 percent or more above the average of the last 10 years then extent is a new record low minimum.

So is a GAC necessary for a such an event? Would just marginally positive conditions for melt be sufficient?
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Re: The 2020 melting season
« Reply #3298 on: July 21, 2020, 01:55:58 PM »
All we need now is for a hurricane to follow the path of 2012’s Sandy if the area/extent is as bad as 2012 come September.
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Re: The 2020 melting season
« Reply #3299 on: July 21, 2020, 01:59:09 PM »
Regarding Bremen concentration I personally am a fan, have had to learn how to read it and not make too much of sudden anomalous concentration changes.  When I see open water mixed with color change or color change that persists and evolves in a logical fashion across multiple days if you can see past the noise then I consider that it is meaningful change.

Completely agree, ArcTickTock, and Aluminium's animations are particularly useful in helpling quickly spotting this on AMSR2.  If those dark areas flit around, it is best to ignore them, and those dark areas correspond with color variations on the other images. 
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