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RikW

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Re: The 2020 melting season
« Reply #3300 on: July 21, 2020, 02:00:36 PM »
I made a table of historic melt numbers according to JAXA SIE

I grouped it in blocks of 5 years and 20 days of melting; Starting day 60 until day 260; Extent melting season is mostly between those days (and it made easy grouping...)

Today is day 201.

At the bottom I compared day 60-199 with 200-259 to see how the melt from yesterday till the end compared with the first part of the season;

At the right I made a table with remaining melt for this season and how that would compare with 'early' season melt and long term average. I added the 217k melt we have had already in the calculation. So the formula for the 3M is 3M + 217k / 7.835k = 41.1%

What I thought, early season high melt (till day 200) doesn't lower late season melt numbers. I thought, less ice available to melt, thus less melting. That isn't true when I check the numbers.

Based on the long-term average day I'd expect 3M at least 3M melt since day 200; So 2.8M to go; Based on the long-term percentage (~46%) it's 3.4M to melt. That means we go below 3M SIE...

Freegrass

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Re: The 2020 melting season
« Reply #3301 on: July 21, 2020, 02:09:58 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.
The last 7 years look mighty similar to the 7 years in between 96 and 03. Those were 7 stable years, followed by 10 disastrous years, and then 7 more stable years again.

Are we in for 10 disastrous years again?
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Pagophilus

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Re: The 2020 melting season
« Reply #3302 on: July 21, 2020, 02:24:34 PM »
A Tale of Two Seasons

The marked differences in ice distribution between 2020 and 2012 continue to grow...

(NSIDC ice extent comparison tool)
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marcel_g

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Re: The 2020 melting season
« Reply #3303 on: July 21, 2020, 03:49:06 PM »
Looking at the GFS forecast on climate reanalyzer for the next 7 days, it looks like predominantly weak low pressures, lots of clouds and no sustained strong winds. There could be a big slow down, at least in extent losses.

I'm going to be watching so see how much energy the system has accumulated and if that translates into bottom melting that will show up in area losses. Or if that requires a lot more wind and waves to pull that heat up to the surface.

werther

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Re: The 2020 melting season
« Reply #3304 on: July 21, 2020, 04:01:22 PM »
The geopotential bulge on 500MB over the Arctic tropopause is fading in the direction of Chukchen Peninsula. Around it, a jet stream loop is enhancing vorticity over ESS, Chukchi Sea and the adjacent part of the CAB. Yes, it reflects in ECMWF and GFS forecasting a 989 mbar low next week. It sweeps Chukchi, ESS and Beaufort.
I won't say it matches the GAAC of 2012. The origin is somewhat different. But the mechanism is the same. There's a bond between low extent, thin pack ice, warm continent and large temp differences between locations with pack ice and open peripheral seas. Next week is poised to be interesting...

Comradez

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Re: The 2020 melting season
« Reply #3305 on: July 21, 2020, 04:18:14 PM »
I wouldn't be so confident as some posters here that the seemingly solid pack in the CAB will hold up well this coming month.  Take a look at what one seemingly solid stretch of the pack along the Laptev front from July 16th to today (click to animate).  Note that:
1.  This was without a Great Arctic Cyclone.
2.  This is not mere dispersion.  The extent front has been marching southwards the whole time.  It's just that the ice in the middle is disintegrating faster than the extent front can catch up to it to re-compactify. 

BornFromTheVoid

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Re: The 2020 melting season
« Reply #3306 on: July 21, 2020, 04:18:58 PM »
Latest simple projection has 7 of the last 20 melt seasons causing a record low, and the 10 year average melt gives a low of 3.53 million km2. Slowest melt (2001) gives a low of 4.39 million km2.
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

UCMiami

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Re: The 2020 melting season
« Reply #3307 on: July 21, 2020, 04:41:50 PM »
I wouldn't be so confident as some posters here that the seemingly solid pack in the CAB will hold up well this coming month.  Take a look at what one seemingly solid stretch of the pack along the Laptev front from July 16th to today (click to animate).  Note that:
1.  This was without a Great Arctic Cyclone.
2.  This is not mere dispersion.  The extent front has been marching southwards the whole time.  It's just that the ice in the middle is disintegrating faster than the extent front can catch up to it to re-compactify.
This is a telling display, and I wonder if the rapid movement of the Laptev Bite toward the pole is actually the result of a similar melt within the 'solid pack' only the edge is keeping pace with the melt so no open areas are actually appearing. Certainly the optics in world view do not look like the pack behind the front edge is compressing into more 'solid' ice. That ice looks the same as it has for the last few weeks with the same or greater greying, which elsewhere is a precursor to melt out.

ArcTickTock

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Re: The 2020 melting season
« Reply #3308 on: July 21, 2020, 07:34:04 PM »
A Tale of Two Seasons

The marked differences in ice distribution between 2020 and 2012 continue to grow...

(NSIDC ice extent comparison tool)

Wow, I was aware of the differences out on the main ice pack but did not realize 2020 was so far ahead of 2012 in the eastern CAA!

GoSouthYoungins

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Re: The 2020 melting season
« Reply #3309 on: July 21, 2020, 07:53:28 PM »
Wow, I was aware of the differences out on the main ice pack but did not realize 2020 was so far ahead of 2012 in the eastern CAA!

And that region is about to get roasted. The press will be moving soon enough. Ice near Ellef Ringnes probably want to go south, and it should get the chance in a few weeks. Which would be terrible. Hopefully the ice is thicker than I think.
big time oops

Killian

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Re: The 2020 melting season
« Reply #3310 on: July 21, 2020, 08:12:07 PM »
Latest simple projection has 7 of the last 20 melt seasons causing a record low, and the 10 year average melt gives a low of 3.53 million km2. Slowest melt (2001) gives a low of 4.39 million km2.

I have a quibble with these sorts of projections: They don't take into account the patterns of melt. Virtually every season rather closely follows a few overall patterns, and virtually every melt season has the specific pattern that the slope of the line in the first half of July continues into mid- or late August. Just tagging on the melt from this point on onto the end of 2020 is not likely to capture the actual potential outcome.

Burnrate

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Re: The 2020 melting season
« Reply #3311 on: July 21, 2020, 08:21:56 PM »
...
...
 Just tagging on the melt from this point on onto the end of 2020 is not likely to capture the actual potential outcome.

I don't think anyone is saying that it will do that.  It is, like he said, a simple projection.  It is another view of how this season compares to others in a basic way and gives another way of looking at how the melt season may progresses based on specific data.

BornFromTheVoid

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Re: The 2020 melting season
« Reply #3312 on: July 21, 2020, 08:22:19 PM »

I have a quibble with these sorts of projections: They don't take into account the patterns of melt. Virtually every season rather closely follows a few overall patterns, and virtually every melt season has the specific pattern that the slope of the line in the first half of July continues into mid- or late August. Just tagging on the melt from this point on onto the end of 2020 is not likely to capture the actual potential outcome.

I largely agree. The projections I post are simple and naive, not meant in terms of any genuine scientific pursuit. Every melt season is different - every year the ice is configured differently in terms of thickness, coverage, age, formation history. The weather is different each year too. In fact, everything is different every year. Even where slopes line up, they can be lining up for completely different reasons. No method so far is capable of capturing the eventual outcome, mine is certainly no different.

We are in uncharted territory here, but there's no harm is playing with the data a bit!
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

jdallen

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Re: The 2020 melting season
« Reply #3313 on: July 21, 2020, 09:01:53 PM »

I have a quibble with these sorts of projections: They don't take into account the patterns of melt. <snip>

I largely agree.
<snip>
We are in uncharted territory here, but there's no harm is playing with the data a bit!

Indeed.  We are in fact wrestling with a "sum of sums" problem.

By latitude and longitude, by ice thickness and water depth, by starting temperatures and shifting albedo, by weather down to a local scale, each factor interacts with and rolls up with the effects of the others to produce the final number.

We are essentially trying to determine if that figure in a trench coat was a man or a sack of ferrets standing on each other's shoulders, and just exactly what path he's about to walk.

What stuff like BFTV does is give us limits inside which our "fractal equations" play out.

We can also try to look to find years with similar conditions and histories - but that's exceptionally difficult as we can't just sample specific states in time.  We have to also examine trajectories (in some cases, literal).  We have to consider interactions and feedbacks within the assembly of mechanisms and metrics.

And BFTV does point out correctly we are in completely uncharted territory here.  We've never seen the Arctic in this state before, as a system, at this particular juncture in time, with this particular and severe set of forces being applied to it.  In short, we can only make educated guesses.  Stuff like what BFTV has posted give us a starting point to do that.
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Killian

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Re: The 2020 melting season
« Reply #3314 on: July 21, 2020, 09:10:54 PM »
Made a table of 2020 extrapolations with some particular dates set as sort of "mile markers" for a quick reference to how the ice is doing. I think these three options bound outcomes pretty well.

Killian

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Re: The 2020 melting season
« Reply #3315 on: July 21, 2020, 09:15:51 PM »
Made a table of 2020 extrapolations with some particular dates set as sort of "mile markers" for a quick reference to how the ice is doing. I think these three options bound outcomes pretty well.

Here's a really rough attempt to extrapolate 2020 from the July trend.


Killian

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Re: The 2020 melting season
« Reply #3316 on: July 21, 2020, 09:25:38 PM »

I have a quibble with these sorts of projections: They don't take into account the patterns of melt. <snip>

I largely agree.
<snip>
We are in uncharted territory here, but there's no harm is playing with the data a bit!

Indeed.  We are in fact wrestling with a "sum of sums" problem.


What stuff like BFTV does is give us limits inside which our "fractal equations" play out.


I wasn't complaining, I had spent the evening doing some of my own before seeing that posted, ironically. I was wishing for from-the-trend extrapolations, too. I had done that a couple days ago but thought they were too rough to post. But, hey, I just did. Someone with more skill can do better ones.

Cheers

Gizmo

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Re: The 2020 melting season
« Reply #3317 on: July 21, 2020, 09:28:03 PM »
It's looking like we're very likely to see a new record minimum this Sept.  I'm not imagining a BOE this year but some of these 'worst case' extrapolations look close enough to put us very close to one or another of the tipping points mentioned here.  The more I look at what's happening now the more worried I get about next summer.  There's going to be record amounts vulnerable of FYI.

ajouis

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Re: The 2020 melting season
« Reply #3318 on: July 21, 2020, 09:38:25 PM »
Another example the pack is very vulnerable this year, also that shows divergence between each thickness/volume model (PIOMAS, Hycom, DMI and ECM) so take it (and them) with a grain of salt
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 Less than 3000 cubic kilometers this Piomas minimum.

igs

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Re: The 2020 melting season
« Reply #3319 on: July 21, 2020, 09:59:24 PM »
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.

They don't see it, they simply assume that a long lasting high pressure system must have compacted (compressed) the ice or stacked it up to 10m hights, an opinion that i do not share.

CAB area is quite low not especially high as it would be in case the above mentioned assumptions were right.

igs

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Re: The 2020 melting season
« Reply #3320 on: July 21, 2020, 10:06:03 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? ???

A good point indeed and apparently some folks dont' look up the date often enough.

Yes, images look similar than what we have seen before but 10-15 days ahea in time compared to the worst and even more so to lesser seasons.

As I posted upthread several weeks ago, once we are around or more than 1M km2 ahead of 2012 it will be hard to lose that ground (not imposible of course)

weatherdude88

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Re: The 2020 melting season
« Reply #3321 on: July 21, 2020, 10:24:51 PM »
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.

They don't see it, they simply assume that a long lasting high pressure system must have compacted (compressed) the ice or stacked it up to 10m hights, an opinion that i do not share.

CAB area is quite low not especially high as it would be in case the above mentioned assumptions were right.


Pagophilus

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Re: The 2020 melting season
« Reply #3322 on: July 21, 2020, 10:33:19 PM »
Current concentration layered on bathymetry already published for earlier dates by Blumenkraft, who also generously introduced me to gif making last year.  Hope it is OK I tread here, Blum'.  If not, I will retreat.  The concentration data is for July 20.

What continues to strike me is that the main icepack continues to sit in an almost exact fit this July over the deep Arctic basin.  The hot Laptev Sea has taken a 'bite' out of the ice, and there is still some rapidly melting ice in the ESS and Chukchi, but otherwise it is a really close fit.

I think most of us acknowledge the ice is in perilous condition... I certainly do.  But if you wanted to put the remaining ice in a place that would maximize its survival, then it would probably be exactly here, where the warm saline waters glide into the depths, and the ice sits on a lens of comparatively cold water.

Of course, it is not just coincidence that the ice is here... it melts back to these boundaries. But the recent sustained high helped gather the ice into this area.  The ice pack is like a flock of lambs crowded into an enclosure, with the wolves and mountain lions waiting outside.  if the icepack is scattered we all know what happens.  But amidst all the predictions of massive further melting, (which may yet come to pass) the ice may be in the best possible place for its partial survival, perched above the deep Arctic basin, for the present.

Images from https://oden.geo.su.se/map/
« Last Edit: July 21, 2020, 10:38:49 PM by Pagophilus »
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Burnrate

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Re: The 2020 melting season
« Reply #3323 on: July 21, 2020, 11:13:41 PM »
It's looking like we're very likely to see a new record minimum this Sept.  I'm not imagining a BOE this year but some of these 'worst case' extrapolations look close enough to put us very close to one or another of the tipping points mentioned here.  The more I look at what's happening now the more worried I get about next summer.  There's going to be record amounts vulnerable of FYI.

The thing that frightens me is that in a complex system like this, as you approach boundaries, you might expect to see new interactions and non linear effects.  No extrapolation would capture those.

If viewing terror was a measure of the state of the ice I would say this year is worse than any other.  I have always watched with fear and excitement but this is different.

tybeedave

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Re: The 2020 melting season
« Reply #3324 on: July 21, 2020, 11:29:33 PM »
is the garlic press long from beginning to operate in earnest?

the ice is movng 5 km westward per day in the lincohn sea.  the floes getting ground up going thru the nares now are oringating from north of greenland.
 
a 5 day comparison shows also that the CAB is rapidly disintergrating:

https://worldview.earthdata.nasa.gov/?v=-1537338.0759939172,-1501801.1950418225,-419130.0759939172,-977513.1950418225&p=arctic&l=Reference_Labels,Reference_Features(hidden),Coastlines,VIIRS_NOAA20_CorrectedReflectance_TrueColor(hidden),VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor&l1=Reference_Labels(hidden),Reference_Features(hidden),Coastlines,VIIRS_NOAA20_CorrectedReflectance_TrueColor(hidden),VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor&ca=true&cv=55

 note that Jones Sound went from 75% ice  to next to nothing in 5 days and the Parry Channel appears to be following the lead of the nares.

looks to me like the press will soon be added to the 'perfect storm' of melt events that have already occurred in 2020, a year to remember with sadness.....

td

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Pagophilus

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Re: The 2020 melting season
« Reply #3325 on: July 21, 2020, 11:38:12 PM »
is the garlic press long from beginning to operate in earnest?

the ice is movng 5 km westward per day in the lincohn sea.  the floes getting ground up going thru the nares now are oringating from north of greenland.
 
a 5 day comparison shows also that the CAB is rapidly disintergrating:
td
I agree.  For the garlic press to operate (once it opens) there will need to be ice being pushed into it.  Right now, the icepack is lifting off the Greenland/Canada coasts, developing those cracks. I presume a considerable change in icepack motion would be needed for the garlic press to come into effective operation.
« Last Edit: July 21, 2020, 11:57:20 PM by Pagophilus »
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igs

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Re: The 2020 melting season
« Reply #3326 on: July 21, 2020, 11:58:04 PM »




Perhaps you overlooked the word MUST, your chart shows the usual or what often happens but that doesn not mean that it always has to be like that, especially under the current special conditions in many aspects.


So get me right, yes it's usual, i doubt the "inevitable" part for the current conditions.

Paul

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Re: The 2020 melting season
« Reply #3327 on: July 22, 2020, 12:28:56 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.

They don't see it, they simply assume that a long lasting high pressure system must have compacted (compressed) the ice or stacked it up to 10m hights, an opinion that i do not share.

CAB area is quite low not especially high as it would be in case the above mentioned assumptions were right.

The ice has been compacted by the high but no doubt there been some melting on top of the ice and from the edges. The evidence of compaction is to compare the ice on this date between now and 2016. 2016 ice is full of holes and dispersion which did play a part in the 2nd half of the melt season with open water reaching 85 degrees north and the ice near the pole very diffused and sorry for itself. This year, I cant see any dispersion in the CAB at this moment in time but obviously the extent of the ice has taken a huge hit and more (warm) open water could affect the CAB ice. Also the ice last year was also fairly compact to other years and yet still reached 2nd lowest in terms of extent so warm SSTS and other factor could very well override any compaction especially as the CAB ice does not look all that thick.

Rod

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Re: The 2020 melting season
« Reply #3328 on: July 22, 2020, 12:50:21 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.

They don't see it, they simply assume that a long lasting high pressure system must have compacted (compressed) the ice or stacked it up to 10m hights, an opinion that i do not share.

CAB area is quite low not especially high as it would be in case the above mentioned assumptions were right.

There is absolutely no question that there has been compaction over the last several days due to the prolonged high pressure system. Anyone looking at the satellite images can see it.  It is basic physics and it is the reason why the extent numbers are currently so far below where they have ever been before on this date.

I don’t know where you got the idea that the ice has been stacked up to 10m heights. That seems very unlikely.  But, high pressure causes the winds to blow the ice north, and low pressure causes the winds to blow the ice south. Extent numbers are largely driven by the direction of the wind.

Personally, I have seen what looks to me like a hell of a lot of surface melting on the compacted ice. The extent drops will slow if we switch to a dominant low pressure system, that is basic physics. However, to my mind the ice looks like shit, and I think it will be hard for it not to set a record this year.

I’m out on a limb saying that, because we still have a long way to go until the minimum in September. Things could happen to preserve extent and area that have nothing to do with how much ice is actually there.

As a PSA, I think it would be helpful for people to visit the JAXA or NSIDC web pages and review how extent and area are measured. Volume is a completely different beast, and is even more complicated.

It seems to me that many of the disagreements on this forum stem from confusion about what the numbers mean, and how they are determined.

People like to crunch numbers and come up with their theories, I get that. But when you are looking at raw data from a system that is not well characterized, you need to remember the numbers don’t always mean what they say.

That is very much true for the numbers we use to measure the sea ice.  They are the best we have, but they are not perfect or absolute.


weatherdude88

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Re: The 2020 melting season
« Reply #3329 on: July 22, 2020, 12:59:42 AM »




Perhaps you overlooked the word MUST, your chart shows the usual or what often happens but that doesn not mean that it always has to be like that, especially under the current special conditions in many aspects.


So get me right, yes it's usual, i doubt the "inevitable" part for the current conditions.

Compactness = Area / Extent. Various satellite sensors (NSIDC / JAXA) and their respective data, tell us 2020 is among the most compact on record.

There is no debate.

Are some on here questioning JAXA and NSIDC sea ice extent and area data? 

bbr2315

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Re: The 2020 melting season
« Reply #3330 on: July 22, 2020, 01:04:15 AM »




Perhaps you overlooked the word MUST, your chart shows the usual or what often happens but that doesn not mean that it always has to be like that, especially under the current special conditions in many aspects.


So get me right, yes it's usual, i doubt the "inevitable" part for the current conditions.

Compactness = Area / Extent. Various satellite sensors (NSIDC / JAXA) and their respective data, tell us 2020 is among the most compact on record.

There is no debate.

Are some on here questioning JAXA and NSIDC sea ice extent and area data?
If record low area is divided by record low extent, then yes, there is a chance that compactness can be higher than other years.

All you are saying is that a record low ice pack is at a record low. LOL. Compactness here is meaningless.

Rod

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Re: The 2020 melting season
« Reply #3331 on: July 22, 2020, 01:09:12 AM »


Are some on here questioning JAXA and NSIDC sea ice extent and area data?

I don’t think anyone is questioning the data.  It is the interpretation of the data that is in dispute.  That is common in all of science. My point with the PSA is that I don’t think everyone knows what the numbers actually mean. 

We are not living in a Star Wars world where we have perfect sea ice data. We are limited by the satellites we use. That does not mean that we don’t have very good data, but it is important to understand the data’s limitations.

I come from a back ground in bench science so this seems obvious to me. But, this seems to be a point of confusion and worth reemphasizing. 

Edit: I am also not sure if I agree with your compactness formula.  It is commonly used on these forums. I know Neven likes it, but I have doubts to its validity. However, that is not germane to the discussion at hand.
« Last Edit: July 22, 2020, 01:21:07 AM by Rod »

ajouis

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Re: The 2020 melting season
« Reply #3332 on: July 22, 2020, 01:33:30 AM »
Yes weatherdude, jaxa and especially nsidc (if I remember well that’s the one that should have been replaced a while ago and that is hanging by a thread), not, unlike bremen, because of artifacts (although the amsr/nsidc area graph indicates this could be the case too), but because of both occasional data errors worsened by old age, and, most importantly, due to the limitation of the tools themselves ie their grid size and resolution. There is a reason why they all differ (amsr2, jaxa, nsidc), and the lack of omniscient all knowing instrument is a big problem in science, especially in less monitored places like the arctic, so it is valid to question it.
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Re: The 2020 melting season
« Reply #3333 on: July 22, 2020, 01:40:44 AM »
Latest simple projection has 7 of the last 20 melt seasons causing a record low, and the 10 year average melt gives a low of 3.53 million km2. Slowest melt (2001) gives a low of 4.39 million km2.

I have a quibble with these sorts of projections: They don't take into account the patterns of melt. Virtually every season rather closely follows a few overall patterns, and virtually every melt season has the specific pattern that the slope of the line in the first half of July continues into mid- or late August. Just tagging on the melt from this point on onto the end of 2020 is not likely to capture the actual potential outcome.
I wouldn't be surprised if we reach a low of 2.2 million km2 this year. The influence of the Laptev and ES sea's open water surface is usually larger than projected.

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Re: The 2020 melting season
« Reply #3334 on: July 22, 2020, 01:59:32 AM »
Crazy .. where ESS/Laptev and Siberia meet : 32'C with rain from a 'hot' little low . 16'C  850hpa with rain spreading into the Arctic basin . We keep on getting glimpses of the future in the now . The Arctic is baking again .. it is weather for dancing naked on the ice , but it's a little off shore .
 As for compaction in action I picked 2 points on WV july 02 , 530km apart . by july 20 they were 480km apart . The points were either side of 80N and gradually moving poleward from the ESS side .
 The dispersal in 2016 help stop the melt as the open waters cooled . The closed close pack may be worse for the ice with warmed water working from below and warm rain from above . b.c.

 
 

 
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 + 2 = 2021 
 (phew)

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Re: The 2020 melting season
« Reply #3335 on: July 22, 2020, 03:24:39 AM »
Made a table of 2020 extrapolations with some particular dates set as sort of "mile markers" for a quick reference to how the ice is doing. I think these three options bound outcomes pretty well.
   Thanks Killian.  Those are very interesting comparative extrapolations.  I find them more informative than the debate about the degree of compaction.  The fact that your extrapolation from 5 low melt years stills ends up at 3.6 M km2 is remarkable and well below the straight line trend, and rougly 8-10 years ahead of where 2020 "should" be on that trend line (eyeball estimate).

    Taking 2012 out of the "Worst case" scenario yields an estimate similar to the "Bad case" scenario at ca. 3.4-3.5.  That reinforces a final estimate of around 3.5.  That would still leave 2012 in 1st place, but not by much. 

      I wonder how warm water melt momentum in 2020 is still unexpressed in the real time measurements.  And with warmer water the chance of cyclone is also lurking in the wings.  Putting those pieces together suggest that 2020 is heading for a near miss 2nd place without any additional anomalously strong melt weather between now and minimum, and may even replace 2012 without any dramatic melt weather, due to momentum.
     
      While another GAC 2012 is unlikely, if there is a strong storm, then it looks like 2020 has a very good chance of going below 2012.  As other ASIF posters have noted, regardless of the record, the ice condition looks terrible and already has one thinking about what kind of setup 2020 is creating for 2021.  The 2019 + 2 = 2021 tag line used by ASIF member be cause is looking prophetic. 

       But that's next year.  The end game for this year looks to be dramatic and historically significant.  We will have numbers soon.
 

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Re: The 2020 melting season
« Reply #3336 on: July 22, 2020, 03:30:36 AM »
Here comes the weak low pressure system. It will probably slow down the short term extent drops.

If it picks up speed, and breaks up the ice through mechanical forces and upwelling warm salty water, this will be a year for the record books.

If it stays weak for the next few weeks, then this season will fizzle out like 2016 and we will probably finish in a strong second place.

My gut is telling me that there is a lot more in store for the melt season, but I will leave it to the weather forecasters to see what they say.

Freegrass

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Re: The 2020 melting season
« Reply #3337 on: July 22, 2020, 03:39:11 AM »
Arctic sea ice is in a downward spiral, and may break a record in 2020

By Andrew Freedman (Washington Post Cashed Version) (No subscription needed)
July 20

If one were to design a weather pattern that’s most efficient at ridding the Arctic of its increasingly fragile ice cover during the region’s summer melt season, it would look like what occurred earlier in the month — clear skies, above-average air temperatures, a high-pressure system across the Central Arctic, and an ongoing heat wave and wildfires in Siberia.

A recent study concluded that the unusual warmth in Siberia could not have happened in the absence of human-caused global warming.

Sea ice loss accelerated in early- to mid-July, bringing sea ice extent — which measures the area of ocean where there’s some ice cover, down to record-low levels for this time of the year.

As of Saturday, the Arctic as a region had an ice extent that was about 193,000 square miles below the previous record low for the date, using data from the Japanese Aerospace Exploration Agency.

In other words, the difference between the sea ice extent on July 18, 2020, and the previous record low for the same date is equivalent to the states of Colorado and Oklahoma combined.

According to the National Snow and Ice Data Center (NSIDC) in Boulder, Colo., which tracks ice trends and climate change, the record-low ice extent is in part the result of the Siberian heat streak that has lasted from January through June, and into July.

As a result of record-warm temperatures all the way to Russia’s Arctic shoreline, with wildfires spotted by satellite near the coast, well above the Arctic Circle, sea ice retreated early along the Siberian coast.

Extremely low sea ice cover can now be found in the Laptev and Barents seas, in particular, NSIDC reported Thursday. “The Northern Sea route appears to be nearly open,” the agency stated in a news update. This means lucrative shipping of liquefied natural gas (LNG) and other valuable goods can begin along a still-treacherous route over the top of Russia, offering faster access to Asian ports from the North Atlantic.

In fact, one LNG tanker set out from the port of Sabetta, on Russia’s Yamal Peninsula on May 18, accompanied by a heavy duty icebreaker. This was the earliest date of such a Northern Sea Route voyage on record, according to the Barents Observer.

“In the Laptev and East Siberian Seas, the sea ice extent is tracking at the record lowest,” Julienne Stroeve, a senior researcher at NSIDC, said via email.

“This May, the melt ponds were quite unusual in the East Siberian Sea, which likely contributed to early melting out of the sea ice, but also because the Arctic Oscillation was strongly positive over winter, this led to lots of new ice formation in that region, which was relatively thin to start with and thus the ice easily melted away with the heat wave in that region,” Stroeve wrote, referring to a weather pattern that affects the distribution of air pressure across the Arctic and North Atlantic oceans.

“Now melt ponds are quite widespread over much of the Arctic Ocean, with anomalously more melt pond development north of Greenland and the Canadian Archipelago, which is also helping to hasten ice melt elsewhere,” she said.

Stroeve took part in a scientific expedition known as MOSAiC, in which a ship with scientists onboard has drifted with the Arctic ice pack for about a year to learn more about this rapidly changing environment. The Arctic region is warming at a rate that is about three times as fast as the rest of the globe, driving myriad changes in the environment, from ice melt to permafrost thaw and increased wildfire activity.

Stroeve said her time aboard the ship during the winter showed her that much of the sea ice in the High Arctic was “relatively thin second-year ice” that grew from about two feet to 6.5 feet thick by the time she left the ship in early March.

“The amount of surface melting we are seeing could easily melt out ice” of that thickness, she said. “Thus I do have a feeling we are on track to reach a new record low for September.”

She added: “However, weather patterns could change and slow the ice melt, but given how warm the first part of July was over most of the Arctic Ocean, I’m not so sure we can stop the inevitable.”

The year with the record-lowest sea ice extent was 2012, and that record occurred as a result of both long-term climate change gradually causing Arctic ice cover to become younger and thinner over time, as well as weather that favored rapid ice loss.

How weather patterns evolve over the next two months will help determine whether 2020 becomes a record-breaking melt season.

“Weather conditions can change and slow things down quite quickly,” said Walt Meier, a senior research scientist at NSIDC. “A record low is possible, but I would say 50/50 at best. We’d need to continue weather patterns advantageous for ice loss through August to remain on a pace to go below the 2012 record minimum.”

Whether this year breaks the 2012 record, computer models are virtually unanimous in showing the occurrence of seasonal ice-free conditions there by mid-century.
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Re: The 2020 melting season
« Reply #3338 on: July 22, 2020, 03:49:25 AM »
OK, this is it.  This is our compact, unrubbled extent.  Our CAB Bastion if you will.

It's due north of Ellesmere.  The lower left hand corner is grounded on an island in the CAA.

To the left, it is bounded by the Beaufort, which *is* rubble, and the upper left hand corner is where the ESS and Chukchi melt in-situ are chewing into it.

Directly above, the Laptev ice boundary is chewing northward at as much as 50km/day, and will almost certainly be passing 85N before the end of this.

To the right, you have a combination of ice being rubbled, melting in situ as it is dumped into the Fram conveyor, or shoved into the emerging killing zone along the Atlantic front to the north of Svalbard and FJL.

This image is about 1.5 million km2.  There is far too little that will survive outside of it for my comfort.
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Re: The 2020 melting season
« Reply #3339 on: July 22, 2020, 03:51:03 AM »
Other areas I referenced in the previous post.
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Freegrass

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Re: The 2020 melting season
« Reply #3340 on: July 22, 2020, 04:22:04 AM »
Latest Five Day Forecast
Wind + Temp @ Surface

Large Gif!
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Re: The 2020 melting season
« Reply #3341 on: July 22, 2020, 04:30:10 AM »
Latest Five Day Forecast
Wind + Temp @ Surface
Looks like a big shove in the direction of the Laptev.
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pearscot

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Re: The 2020 melting season
« Reply #3342 on: July 22, 2020, 04:43:34 AM »
Latest Five Day Forecast
Wind + Temp @ Surface

Large Gif!

As bad as I though the long-lived high pressure system was, the new pattern looks just as bad. The ice is still going to be under intense heat and melting pressure, just in different, smaller areas. I take the temps from windy.com as a rough average for a large areas, but northern Siberia is right around 90f at the moment...I think any ice which touches the Laptev at this point will melt seemingly instantly
pls!

Freegrass

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Re: The 2020 melting season
« Reply #3343 on: July 22, 2020, 04:46:53 AM »
Latest Five Day Forecast
Wind + Temp @ Surface
Looks like a big shove in the direction of the Laptev.
It sure looks that way, although the wind is not that strong. But I do think the century drops are over for now.

Siberia still incredibly hot. And the north of Greenland is not too shabby either...

Edit: Where does that heat north of Greenland come from? Is that adiabatic heating? Or just the sun heating the rocks? Or both?
« Last Edit: July 22, 2020, 05:06:19 AM by Freegrass »
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oren

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Re: The 2020 melting season
« Reply #3344 on: July 22, 2020, 05:25:11 AM »
AMSR2 Uni Hamburg (3.125 km grid) area and extent charts. Next post is the same for the CAB.
2020 is certainly more "compact" than usual. This does not mean the situation is good. Surprisingly, in the CAB itself "compactness" is average, meaning the anomaly is found elsewhere.

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Re: The 2020 melting season
« Reply #3345 on: July 22, 2020, 05:25:45 AM »
CAB charts.

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Re: The 2020 melting season
« Reply #3346 on: July 22, 2020, 05:28:57 AM »
OK, this is it.  This is our compact, unrubbled extent.  Our CAB Bastion if you will.

It's due north of Ellesmere.  The lower left hand corner is grounded on an island in the CAA.

To the left, it is bounded by the Beaufort, which *is* rubble, and the upper left hand corner is where the ESS and Chukchi melt in-situ are chewing into it.

Directly above, the Laptev ice boundary is chewing northward at as much as 50km/day, and will almost certainly be passing 85N before the end of this.

To the right, you have a combination of ice being rubbled, melting in situ as it is dumped into the Fram conveyor, or shoved into the emerging killing zone along the Atlantic front to the north of Svalbard and FJL.

This image is about 1.5 million km2.  There is far too little that will survive outside of it for my comfort.
Thanks. That is why I said that I don't see any "widespread" compaction. I understand equations and reliable data, but it is good to see these images and not just blindly follow data. If you use a phone everyday to get numbers but do not look to see for yourself, data can be accurate but misleading as to the overall state of the ice.
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Re: The 2020 melting season
« Reply #3347 on: July 22, 2020, 06:41:32 AM »
Well, regarding a new September minimum it is all about the Beaufort now!  Everywhere but there it has been a very bad melt season and even less than expected losses in all the other seas may be enough.  It is certain however that without sustained heavy losses in the Beaufort from here on out there will be no record minimum this year.

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Re: The 2020 melting season
« Reply #3348 on: July 22, 2020, 06:46:41 AM »
Made a table of 2020 extrapolations with some particular dates set as sort of "mile markers" for a quick reference to how the ice is doing. I think these three options bound outcomes pretty well.
   Thanks Killian.  Those are very interesting comparative extrapolations.  I find them more informative than the debate about the degree of compaction.  The fact that your extrapolation from 5 low melt years stills ends up at 3.6 M km2 is remarkable and well below the straight line trend...

    Taking 2012 out of the "Worst case" scenario yields an estimate similar to the "Bad case" scenario at ca. 3.4-3.5.  That reinforces a final estimate of around 3.5.  That would still leave 2012 in 1st place, but not by much.

Thanks for the feedback. I think the patterns are vital. There is too much focus on data points here - and everywhere, frankly. I'm a permaculturist, so looking at things "from patterns to details" is default. Both sides tell you something, but the patterns give the details their overall shape and form.

By their nature, the details will engender more conversation, but I'd like to see more noticing of the patterns. Those two huge drops in 2012, e.g. One we know, but what about the first? Nobody seems interested, but that could be a vital clue into potential early season melt risks. Without that first one, 12's drop isn't nearly as astonishing.

E.g.

Quote
I wonder how warm water melt momentum in 2020 is still unexpressed in the real time measurements.  And with warmer water the chance of cyclone is also lurking in the wings.

That's THE question: How energy has entered the system? How much was already there?

I fully believe we hit a climate shift sometime in the last 2 to 5 years, or else the last two years don't really make sense globally and in the Arctic. Patterns.

We shall see.

Freegrass

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Re: The 2020 melting season
« Reply #3349 on: July 22, 2020, 07:05:28 AM »
Sea ice concentration from 21/06/20 to 21/07/20
This animation nicely shows the ice compaction during the last month.

http://bulletin.mercator-ocean.fr/en/permalink/PSY4/animation/3/20200620/20200721/6/1
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