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Tigertown

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Re: IJIS
« Reply #4700 on: July 27, 2017, 10:06:59 PM »
I will comment on that in the suggestions thread, as I know there has been enough off topic elsewhere. Maybe anyone else who wants to say anything will do it there.

gerontocrat

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Re: IJIS
« Reply #4701 on: July 27, 2017, 10:18:29 PM »
A man's gotta do what a man's gotta do.
Neven told me off once - and I deserved it.
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Juan C. García

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Re: IJIS
« Reply #4702 on: July 28, 2017, 05:58:13 AM »
A drop of 87,733 km2.
And the Bremen AMSR2 picture shows weakness on the ASI.
There still some story that needs to be written.

https://seaice.uni-bremen.de/data/amsr2/today/Arctic_AMSR2_nic.png
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.

Espen

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Re: IJIS
« Reply #4703 on: July 28, 2017, 08:29:17 AM »
IJIS:

6,770,879 km2(July 27, 2017)down 87,733 km2 and 5th lowest measured for the date.
Have a ice day!

Shared Humanity

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Re: IJIS
« Reply #4704 on: July 28, 2017, 03:37:37 PM »
Espen....

I have made this type of comment before when this thread hit 1 million views but I would like to thank you again for being so diligent in posting this number. We are now approaching 1.5 million views and 5000 comments both of which are the highest of any thread on this forum.

This thread is far from useless. I only hope that the rest of us can continue to reflect on this chart and make relevant comments as to what it is telling us.

Thank you again.

gerontocrat

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Re: IJIS
« Reply #4705 on: July 28, 2017, 04:02:00 PM »
The numbers still refuse to support a record low extent, despite some recovery in daily extent reduction. Here we go. (JAXA numbers, of course).

On average (2007-2016) by now (27 July) 75% of the extent loss from max to min has happened, that is 7.55 of 10.03 million km2. Just 2.48 million km2 for the remainder of the season.

2017 extent reduction so far is 7.11. million km2, some 440k below that average. To put it another way, with about 50 days of the melt season left, that equates to about 9 days of the average melt per day in the remainder of the season.

As of 27 July, 2017 extent is 405 thousand km2 greater than 2012.

And yet SST anomalies, air temperatures and images and analysis from all the other threads contradict this sluggish rate of extent loss.

ps: Greenland melt has suddenly happened in a big way in complete contrast to the season so far. So can the Arctic Ocean?
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mmghosh

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Re: IJIS
« Reply #4706 on: July 28, 2017, 04:07:20 PM »
Its amazing (to me anyway) that 2017 has held on so closely to 2016 for so long in spite of DMI 80 being so long below normal throughout virtually the whole melt season.

Shared Humanity

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Re: IJIS
« Reply #4707 on: July 28, 2017, 04:19:36 PM »
The numbers still refuse to support a record low extent, despite some recovery in daily extent reduction. Here we go. (JAXA numbers, of course).

On average (2007-2016) by now (27 July) 75% of the extent loss from max to min has happened, that is 7.55 of 10.03 million km2. Just 2.48 million km2 for the remainder of the season.

2017 extent reduction so far is 7.11. million km2, some 440k below that average. To put it another way, with about 50 days of the melt season left, that equates to about 9 days of the average melt per day in the remainder of the season.

As of 27 July, 2017 extent is 405 thousand km2 greater than 2012.

And yet SST anomalies, air temperatures and images and analysis from all the other threads contradict this sluggish rate of extent loss.

ps: Greenland melt has suddenly happened in a big way in complete contrast to the season so far. So can the Arctic Ocean?

Thank you for this comment. This is exactly the kind of detailed analysis of IJIS that helps anyone who visits to get a more thorough understanding of what is likely to happen.

Clearly, a Blue Ocean Event is impossible this year and a new minimum, beating 2012, is very unlikely. 2nd place is still a possibility but we are running out of time.

Pavel

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Re: IJIS
« Reply #4708 on: July 28, 2017, 04:38:27 PM »
I think the final plunge on IJIS will be in late August and September. The Beaufort gyre should melt out in September, CAB will have mostly thin and dispersed ice with holes. Any export of CAB ice to ESS/Chukchi/Laptev/Kara/Barents will be the final journey to ice and no GAC needed.

magnamentis

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Re: IJIS
« Reply #4709 on: July 28, 2017, 04:51:02 PM »
a further extent stall in the making that at the same time will prime the reminder of the then illusionary large extent for the "coup de grace" ;)


Shared Humanity

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Re: IJIS
« Reply #4711 on: July 28, 2017, 04:53:07 PM »
Sorry about those links, technically challenged but, if you click on them and then click again, you will get to the charts.

gerontocrat

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Re: IJIS
« Reply #4712 on: July 28, 2017, 05:20:16 PM »
Sorry about those links, technically challenged but, if you click on them and then click again, you will get to the charts.

Maybe this will help.
What I do to get an image into a post is start with "right click" on the image. This works with most programs. If I want the whole image I then choose "save image as" and save it.

If I want to only use part I choose "copy the image" and paste it into into a cheapo freebie program like paint (clever stuff like photoshop is beyond my technical skills) and select the bit I want (select and then crop) and save that.

Then in my post I can go to to "choose image" in the  "Attachments and other options" and bingo, 'tis done.



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"And that's all I'm going to say about that". Forrest Gump
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johnm33

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Re: IJIS
« Reply #4713 on: July 28, 2017, 09:35:20 PM »
SH click from TT [iirc]

anotheramethyst

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Re: IJIS
« Reply #4714 on: July 28, 2017, 10:08:06 PM »
In 2012 before the GAC...


Thank you for that!  I wasn't watching the Arctic ice yet, then.  From October of 2011 to September of 2012 I was watching the crazy hot weather that swept through Norrh America.  It was HOT.  By about March, every month, it was a new "hottest 12 consecutive months on record" for the US.  At the peak, record low temperatures throughout the northern US and Canada were beating previous record highs.  Hundred-year old temperature records were smashed.  The closer it was to the Arctic, the greater the record difference.  There was A LOT of heat. 

I'm not saying we will never see another 2012.  I AM saying it was an unusual year, for multiple reasons.  As the planet warms, it will take less of an outlier year to beat the record, but it helps to keep in mind what actually happened in 2012.  I wish I had been watching the Arctic!! (Though I did catch that 95% surface melt event in Greenland).  Incidentally, that event led me here, I've been addicted since the 2013 season.  :)

Crocodile23

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Re: IJIS
« Reply #4715 on: July 30, 2017, 10:48:08 AM »
Why no updates in the last 2 days? Anyone knows when it will be back again normally?

gerontocrat

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Re: IJIS
« Reply #4716 on: July 30, 2017, 11:04:15 AM »
Why no updates in the last 2 days? Anyone knows when it will be back again normally?
Maintenance, I guess. Happens every few weeks usually at weekends. Usually back on Monday am
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pauldry600

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Re: IJIS
« Reply #4717 on: July 30, 2017, 11:20:04 AM »
Id imagine its at 6.64m around about at the moment

Conservatively guess it dropped to 6.7m on day 1
And 6.64m on day 2.

Could be worse as pacific has had a bit of a bite.

jplotinus

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Re: IJIS
« Reply #4718 on: July 31, 2017, 05:26:46 AM »
Id imagine its at 6.64m around about at the moment

Conservatively guess it dropped to 6.7m on day 1
And 6.64m on day 2.

Could be worse as pacific has had a bit of a bite.

Too conservative. 6.57 was reached on day 2 (29th July).

Espen

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Re: IJIS
« Reply #4719 on: July 31, 2017, 09:11:47 AM »
IJIS:

6,496,068 km2(July 30, 2017)and 4th lowest measured for the date.
Have a ice day!

oren

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Re: IJIS
« Reply #4720 on: July 31, 2017, 09:56:07 AM »
~275k in 3 days.

Pavel

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Re: IJIS
« Reply #4721 on: July 31, 2017, 10:30:28 AM »
IJIS looks stubborn cause I was expecting bigger drops. Thin ice, probably strong storms till the end of melting season. Let's see what will happen

gerontocrat

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Re: IJIS
« Reply #4722 on: July 31, 2017, 12:14:59 PM »
On 30th July JAXA sea ice extent went lower (by about 50,000 km2) than the average 1990's  minimum. About 1 million km2 to go to get below the average 2000's minimum (late August?).
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pauldry600

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Re: IJIS
« Reply #4723 on: July 31, 2017, 02:40:48 PM »
Id expect the early 4millions is now the bookies favorite
with my own 3.7m 10/1

I need a lot of storms.

Plus top earth must be soon stopping melting completely with impending dark

jdallen

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Re: IJIS
« Reply #4724 on: July 31, 2017, 08:17:49 PM »
IJIS looks stubborn cause I was expecting bigger drops. Thin ice, probably strong storms till the end of melting season. Let's see what will happen
It's turning to slush and spreading out.  Seems to be a side effect of the weak pack we have, as the ice appears to be breaking up into smaller pieces far more readily, which reduces melt ponding.  The cloudiness then prevents sunlight from providing the coup de grace.  So far, it looks like a strong ice supporting feedback mechanism.  However, that storm... we will see how it deals with that.
This space for Rent.

Espen

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Re: IJIS
« Reply #4725 on: August 01, 2017, 10:41:35 AM »
IJIS:

6,444,778 km2(July 31, 2017)down 51,290 km2 and 5th lowest measured for the date.
Have a ice day!

gerontocrat

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Re: IJIS
« Reply #4726 on: August 01, 2017, 11:54:49 AM »
With modest daily extent reduction, the story has not changed a lot.

Caveat: On advice of they who know about weather forecast reliability, I normally ignore anything more than 5 days ahead. But weather-forecast.com has been forecasting hairy weather next week for a few days now. Not a GAC but a bit of a game-changer?
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Shared Humanity

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Re: IJIS
« Reply #4727 on: August 01, 2017, 03:41:50 PM »
In a couple of days, 2012 began its race to the bottom. Will 2017 continue to play with the pack or will it make a similar dive?

The SIE dive occurred during the GAC of 2012...

http://onlinelibrary.wiley.com/doi/10.1029/2012GL054259/abstract

...and a large amount of ice extended precariously into the Chukchi and ESS, vulnerable to such a storm.

I do not believe the conditions are right for a repeat and expect that 2017 will continue to dance with the lower end of the pack. 2nd place is still a strong possibility. Would not be surprised to see 4th and 7th place is not out of the question.
« Last Edit: August 01, 2017, 05:20:17 PM by Shared Humanity »

Shared Humanity

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Re: IJIS
« Reply #4728 on: August 01, 2017, 05:29:08 PM »
Decided to post both July 31, 2012 and July 31 2017 together and use NIC colors as it provides a better contrast IMHO.

The ice was primed for the GAC of 2012. Even if a similar storm were to occur, I believe we would get dissimilar results due to the distinct starting points.

Cato

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Re: IJIS
« Reply #4729 on: August 01, 2017, 05:48:01 PM »
Thanks Shared Humanity for your interesting post. IMHO the LP will not significantly impact the ice extension as it is forecast to affect an area where ice is rather compact. 2012 ice conditions were terrible at this same time over Beaufort and Chuckhi, and more vulnerable as a result.

Generally speaking I don't expect a major ice extension decrease in the next 7-10 days based on the synoptic configuration.

Neven

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Re: IJIS
« Reply #4730 on: August 01, 2017, 08:46:35 PM »
You guys need to continue in the 2017 melting season thread.  :)
Il faut comparer, comparer, comparer, et cultiver notre jardin

Shared Humanity

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Re: IJIS
« Reply #4731 on: August 01, 2017, 09:46:21 PM »
You guys need to continue in the 2017 melting season thread.  :)

Just checked in there. They're talking about zombie hordes??????  :o

Espen

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Re: IJIS
« Reply #4732 on: August 02, 2017, 09:44:58 AM »
IJIS:

6,348,955 km2(August 1, 2017)down 95,823 km2 and 5th lowest measured for the date.
Have a ice day!

polynya

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Re: IJIS
« Reply #4733 on: August 02, 2017, 07:00:47 PM »
I enjoy this forum so much but normally just lurk.

If I'm not mistaken, we've now entered a period where the lowest five years (2007, 2011,2012,2015,2016) are separated from the rest of the pack for the rest of the season until the September minimum. As of a few days from now I think this will also be true of NSIDC extent.

Since 2017 is within that top-five pack by both measures, it seems likely to me that 2017 will finish no "worse" than 6th place (somewhere in the top 6).
« Last Edit: August 02, 2017, 07:06:38 PM by polynya »

Shared Humanity

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Re: IJIS
« Reply #4734 on: August 02, 2017, 10:38:42 PM »
I enjoy this forum so much but normally just lurk.

If I'm not mistaken, we've now entered a period where the lowest five years (2007, 2011,2012,2015,2016) are separated from the rest of the pack for the rest of the season until the September minimum. As of a few days from now I think this will also be true of NSIDC extent.

Since 2017 is within that top-five pack by both measures, it seems likely to me that 2017 will finish no "worse" than 6th place (somewhere in the top 6).

I think you are likely correct but, then again, I predicted the NW passage would be open early this year.

Espen

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Re: IJIS
« Reply #4735 on: August 03, 2017, 09:32:14 AM »
IJIS:

6,258,935 km2(August 2, 2017)down 90,020 km2 and 4th lowest measured for the date.
« Last Edit: August 03, 2017, 11:48:31 AM by Espen »
Have a ice day!

PSJ

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Re: IJIS
« Reply #4736 on: August 03, 2017, 11:08:44 AM »
IJIS:

5th lowest measured for the date.

Looks like 4th?

Shared Humanity

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Re: IJIS
« Reply #4737 on: August 03, 2017, 04:25:10 PM »
IJIS:

6,258,935 km2(August 2, 2017)down 90,020 km2 and 4th lowest measured for the date.

This next week will reveal a lot.

magnamentis

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Re: IJIS
« Reply #4738 on: August 03, 2017, 04:47:17 PM »
IJIS:

6,258,935 km2(August 2, 2017)down 90,020 km2 and 4th lowest measured for the date.

This next week will reveal a lot.

there will be years ahead when the key event will take place in july and there will be years ahead when the key events will take place in september, only because 2012 events happened the second week of august does not mean much for this year, especially because the situation is totally different with much less MYI and much thinner ice in general.

the possibility that the big drops will occure later in the season is higher than earlier in the season IMO because higher temps extent more easily into fall now and the higher humidity somehow protects the ice during summer more often in the future, especially during peak-insolation periods in june and july.

the state in which the remaining ice currently is would allow for a huge drop in september given the right winds etc.

of course, it's possible that none of the necessary events will take place any given year and it will probably take another 3-5 years to reach 2012 without special events like GAC etc. at the right time between early august and early september.

Espen

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Re: IJIS
« Reply #4739 on: August 04, 2017, 09:33:16 AM »
IJIS:

6,180,412 km2(August 3, 2017)down 78,523 km2 and 4th lowest measured for the date.
Have a ice day!

gerontocrat

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Re: IJIS
« Reply #4740 on: August 04, 2017, 12:16:25 PM »
Using Jaxa data as at 3rd August.
On average (last 10 years) 80 percent (8 million km2) of total ice extent loss for the season is done.
2017 extent loss to date is 7.7 million km2, 300,000 km2 ( 4 %) less than that average.

PIOMAS 2017 volume (July) is near as dammit the same as 2012, despite that 2012 extent loss to date was 8.8 million km2, 1.1 million km2 greater than this year. Just shows in what bad shape the 2017 ice was this spring ?

Meanwhile, there is (on average) just 20%, 2 million km2 extent loss to go.
2012 melt to end of season from 3rd August was 2.7 million km2, i.e. 700,000 km2 (37%) more than that average.
Something significant needs to happen with the weather to get to 2nd lowest ?
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pauldry600

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Re: IJIS
« Reply #4741 on: August 04, 2017, 02:40:00 PM »
Yeah and because theres so little ice now every year the min day gets earlier so the first week of september is the end in my book.

3.7m still 10/1 :)

4.2m prob favorite

Andreas T

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Re: IJIS
« Reply #4742 on: August 04, 2017, 02:50:00 PM »
.....

the possibility that the big drops will occure later in the season is higher than earlier in the season IMO because higher temps extent more easily into fall now and the higher humidity somehow protects the ice during summer more often in the future, especially during peak-insolation periods in june and july.

the state in which the remaining ice currently is would allow for a huge drop in september given the right winds etc.
....
a reasonable comment about the ice (and not talking about yourself for a change, weiter so!) I very much agree. (please don't reply, I promise to stop commenting on your comments)
The low volume makes it possible that ice covered areas which survived the meltseason in previous years just won't last that long because the thickness is not enough to survive the bottom melt between now and mid September.
In area and extent 75cm of ice counts as much as 1m but with a melt rate of 3cm/day (just as an example) one makes it to the end of the month, the other does not. Time will tell.

DavidR

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Re: IJIS
« Reply #4743 on: August 05, 2017, 05:33:19 AM »
A bid drop for IJIS today 138K, sees 2017 take the lead as having the biggest fall for August so far, nearly 100K more than 2012 and just  more than 2016. The season remains interesting.   
Toto, I've a feeling we're not in Kansas anymore

Espen

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Re: IJIS
« Reply #4744 on: August 05, 2017, 09:17:44 AM »
IJIS:

6,041,914 km2(August 4, 2017)down 138,498 km2 and 4th lowest measured for the date.
Have a ice day!

Bill Fothergill

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Re: IJIS
« Reply #4745 on: August 05, 2017, 10:01:54 AM »
Yeah and because theres so little ice now every year the min day gets earlier so the first week of september is the end in my book.


The available data might suggest otherwise.

Here is a link to a NASA article charting the variations in the onset of both melt and refreeze. I can't recall reading any paper which suggests either trend is likely to reverse. On the other hand, I do recall reading at least one paper which extrapolates this continuing divergence in the onset of melt and refreeze many decades into the future. (Needless to say, I can't put my hands on it at the moment.)   :-[ :-[ :-[

https://neptune.gsfc.nasa.gov/csb/index.php?section=54

The relevant diagram from this NASA article is appended below.


Cato

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Re: IJIS
« Reply #4746 on: August 05, 2017, 10:19:32 AM »
Lots of compaction due to the action of rather strong winds from bering towards caa and cab. One or two more days like this, then dispersion should gain momentum IMHO. Interesting end of season I do quite agree.

oren

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Re: IJIS
« Reply #4747 on: August 05, 2017, 01:11:48 PM »
Here is a link to a NASA article charting the variations in the onset of both melt and refreeze.
The relevant diagram from this NASA article is appended below.
Bill, this article shows an average, while for IJIS min purposes it's enough that a refreeze hits somewhere.
Quote
The following figure shows average melt onset, freeze onset, and average melt duration in days for the entire Arctic.
2016 had an early freeze onset in the central CAB, on Sep 10, but a very late freeze arctic-wide. I speculate that as melt progresses towards the north pole in the years to come, freeze onset dates might actually become slightly earlier rather than later.
The following chart shows the dates for IJIS extent minima. In general there seems to be no trend. More accuracy can be achieved by averaging around the minimum to avoid noise.

Bill Fothergill

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Re: IJIS
« Reply #4748 on: August 05, 2017, 02:04:31 PM »
I speculate that as melt progresses towards the north pole in the years to come, freeze onset dates might actually become slightly earlier rather than later.
The following chart shows the dates for IJIS extent minima. In general there seems to be no trend. More accuracy can be achieved by averaging around the minimum to avoid noise.
Oren, I realise that, in any given year, a polyna at higher latitude is likely to commence its autumnal refreeze at an earlier date than an equivalent polyna at a lower latitude. I can therefore see how one might expect that the gradual pole-ward retreat of peripheral ice, might indicate that refreezing could commence earlier.

This viewpoint, however, might fail to fully incorporate the ice/albedo positive feedback mechanism, which, as you know, results in greater heat storage within the body of the ocean. It is this cumulative build up in the heat content which would serve to delay refreeze.

During the period since I posted a link to that NASA article, I managed to find the paper I had mentally misplaced. (Something which is happening with alarming frequency as the years go by.)

The lead author was Julienne Stroeve - a name I'm certain you recognise - and here is an open access link to the AGU's Geophysical Research Letters article...
http://onlinelibrary.wiley.com/doi/10.1002/2013GL058951/full

Another related paper would be this one, which has Walt Meier as the lead author...
http://onlinelibrary.wiley.com/doi/10.1002/2013RG000431/full

In either article, doing a simple search on the term "delay" gets one quickly to the relevant sections.

However, you are completely correct in pointing out that there are significant differences when one looks at regions, rather than the Arctic as a whole. Quoting from Para 3.3 (Relationship Between Autumn Freezeup and Sea Surface Temperatures) in the Stroeve paper...

"While this is representative of the Arctic as a whole, there are regional differences. In the Chukchi, Beaufort, E. Siberian, Laptev, Kara, and Barents seas, the observed freezeup delay falls within the estimated value (Table S3), suggesting the delay in autumn freezeup is largely driven by the observed increases in SSTs in these regions. These SST increases, together with recent trends toward warmer air temperatures in September (Figure S8), result in a small difference in the air-ocean temperature difference, limiting the amount of latent heat released and a delay in sea ice formation.

Regions outside of the Arctic basin do not appear to show this same relationship however (i.e., Sea of Okhotsk, Bering, Hudson, and Baffin Bay, E. Greenland Sea). Instead large discrepancies between the observed changes in autumn freezeup and that estimated based on the change in SSTs are found, with the actual freezeup occurring between 1 week and 1 month earlier than estimated by equation (3). All these regions, except for Hudson Bay show earlier freezeup in 2000–2012 compared with that in 1982–1999, while SSTs have generally warmed. Trends toward cooler September air temperatures (Figure S8) in these regions may partly explain this discrepancy. While trends are toward warmer SSTs and higher OHC, the air-ocean temperature difference is becoming larger, allowing for the sea surface to release latent heat at a faster rate and for sublimation of sea ice to occur sooner. Ocean dynamics could also be playing an important role in the amount of sea ice found, particularly in the E. Greenland Sea.

In summary, while these preliminary results look promising, a need remains for more extensive research and better understanding of the processes affecting freezeup on a regional scale."


Espen

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Re: IJIS
« Reply #4749 on: August 06, 2017, 10:44:05 AM »
IJIS:

5,961,697 km2(August 5, 2017)down 80,217 km2 and 3rd lowest measured for the date.
Have a ice day!