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Juan C. García

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Re: 2018 sea ice area and extent data
« Reply #1850 on: October 09, 2018, 05:37:06 AM »
[ADS-NIPR-JAXA] ASI Extent.

October 8th, 2018: 4,934,001 km2, a small increase (for the date) of 17,869 km2
2018 is now the 2nd lowest on record.
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.

Phil42

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Re: 2018 sea ice area and extent data
« Reply #1851 on: October 09, 2018, 01:46:55 PM »
So, here's an interesting tidbit: the current lowest NIPR extent records for October 16 to 19 belong to 2007, the only remaining year before 2010 to have any of its days be the lowest extent. 2018 has a decent chance of ending that though.

This one got me thinking how likely it is for 2018 to set new records in the near future and I came up with this small table. It shows, what average daily extent changes are needed to set a new record in x days.

How to read it (10 days as example): If 2018 has an average daily extent change of +96'125 km2 or less during the next 10 days, it will break the current record of 5'991'377 km2 held by 2007 for 19th October. I hope that kind of makes sense.

So, even with daily increases of 100k as of today, 2018 would still set a new record in 11 days.

Ned W

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Re: 2018 sea ice area and extent data
« Reply #1852 on: October 09, 2018, 02:09:31 PM »
Here's an updated version of a chart I posted last week, showing each year's JAXA extent aligned relative to the date of the Sept. minimum:


The X axis for each year is shifted to start 4 weeks before each year's minimum (the mins occur on day 29) and the Y axis shows extent on each day relative to that year's minimum.

The dark-blue outlier (high values on the left half of the chart, low values on the right) is 2008.  It came in steeply and hit an early minimum, bounced back up sharply, then declined back down almost to the same minimum a week later, before starting its refreeze for real. 

oren

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Re: 2018 sea ice area and extent data
« Reply #1853 on: October 09, 2018, 06:04:19 PM »
This one got me thinking how likely it is for 2018 to set new records in the near future and I came up with this small table. It shows, what average daily extent changes are needed to set a new record in x days.
Nice table.

Alexander555

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Re: 2018 sea ice area and extent data
« Reply #1854 on: October 09, 2018, 07:51:22 PM »
That would place both 2017 and 2018 below 2007 and 2012. Looks like something is acting like a break in summer, and it's gone after summer.

Dharma Rupa

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Re: 2018 sea ice area and extent data
« Reply #1855 on: October 09, 2018, 10:38:14 PM »
That would place both 2017 and 2018 below 2007 and 2012. Looks like something is acting like a break in summer, and it's gone after summer.

Or perhaps the break in Summer is the same as the gas in Winter -- water vapor.

GoSouthYoungins

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Re: 2018 sea ice area and extent data
« Reply #1856 on: October 10, 2018, 12:19:08 AM »
Currently headed toward a record low. We have been falling behind due to lack of freezing in the CAB. The CAB will likely start catching up with recent years within the next 3 weeks. But in 2 weeks the Laptev will start falling far behind recent years. And by the start of November the Chukchi will start falling behind. All other things being normalish, I expect the above to keep the extent at record lows for most of the rest of the year.
big time oops

Shared Humanity

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Re: 2018 sea ice area and extent data
« Reply #1857 on: October 10, 2018, 12:54:52 AM »
That would place both 2017 and 2018 below 2007 and 2012. Looks like something is acting like a break in summer, and it's gone after summer.

Or perhaps the break in Summer is the same as the gas in Winter -- water vapor.

I agree. A new regime caused by vast stretches of open water with the remaining ice so fractured as to be venting moisture into the atmosphere across the CAB.

Juan C. García

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Re: 2018 sea ice area and extent data
« Reply #1858 on: October 10, 2018, 05:46:35 AM »
[ADS-NIPR-JAXA] ASI Extent.

October 8th 9th, 2018: 4,967,777 km2, an increase of 33,776 km2
October 8th 9th on 2010's Average:  5,588,736 km2, an increase of 94,717 km2
[2010's Average] - [2008]:  620,959 km2.
2018 is the 2nd lowest on record.
« Last Edit: October 10, 2018, 12:32:04 PM by Juan C. García »
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.

etienne

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Re: 2018 sea ice area and extent data
« Reply #1859 on: October 10, 2018, 08:00:00 AM »
Hello,
Just an idea for Juan C.Garcia's table. I like it very much, and would find interesting, specially this year, to have one extra column showing the difference between curent value and yearly minimum.  This would allow to see what is the freezing trend.
Etienne

Juan C. García

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Re: 2018 sea ice area and extent data
« Reply #1860 on: October 10, 2018, 12:21:33 PM »
Hello,
Just an idea for Juan C.Garcia's table. I like it very much, and would find interesting, specially this year, to have one extra column showing the difference between curent value and yearly minimum.  This would allow to see what is the freezing trend.
Etienne


Like this?  ;)
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.

Phil42

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Re: 2018 sea ice area and extent data
« Reply #1861 on: October 10, 2018, 02:19:41 PM »
Nice table and graph. Really shows how extraordinary the beginning of the 2018 melting season is. I would love to see an update on this in a week or so, since the high temperature anomalies in the Arctic are not expected to drop in the coming week.

Wipneus

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Re: 2018 sea ice area and extent data
« Reply #1862 on: October 10, 2018, 05:52:57 PM »
The Basin-only NSIDC graphs are starting to look very strange, particularly the area graph.

Shared Humanity

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Re: 2018 sea ice area and extent data
« Reply #1863 on: October 10, 2018, 07:00:03 PM »
If you look only at the trend, both are other worldly. All of the other years were experiencing a rapid growth in area and extent by now.

What is going on?

Ned W

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Re: 2018 sea ice area and extent data
« Reply #1864 on: October 10, 2018, 07:16:12 PM »
Nice table and graph. Really shows how extraordinary the beginning of the 2018 melting season is.

I agree it's a nice graph, but there is the issue that it kind of conflates "rate of refreezing" with "date of the minimum".  A year with an early minimum will have had more days to refreeze by now, vs a year with a late minimum. 

Here's an alternate version -- instead of looking at extent gain at a given date, it's extent gain during the first X days after whenever the minimum was:


2018 is still in the slower-freezing half, but it's not an outlier.

Which of these is a "better" way to look at it?  Not sure.  Probably good to consider both.

anaphylaxia

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Re: 2018 sea ice area and extent data
« Reply #1865 on: October 10, 2018, 07:26:48 PM »
Nice table and graph. Really shows how extraordinary the beginning of the 2018 melting season is.

I agree it's a nice graph, but there is the issue that it kind of conflates "rate of refreezing" with "date of the minimum".  A year with an early minimum will have had more days to refreeze by now, vs a year with a late minimum. 

Here's an alternate version -- instead of looking at extent gain at a given date, it's extent gain during the first X days after whenever the minimum was:


2018 is still in the slower-freezing half, but it's not an outlier.

Which of these is a "better" way to look at it?  Not sure.  Probably good to consider both.

Maybe if we would normalize for the extent minimum then the percentage gain since minimum would be a better measure?

oren

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Re: 2018 sea ice area and extent data
« Reply #1866 on: October 10, 2018, 08:24:41 PM »
I think 2018's "natural" minimum would have been earlier, and the real anomalous behavior was during mid-September when the ESS refused to shrink.
In general, the day of the minimum is somewhat arbitrary and sorting everything by gain since minimum IMHO distorts more than it improves.
I think the better comparison is gain since date X, as most years behave similarly at this time of year after the sun sets on the Arctic. But this also creates a distortion, since a year with a very low minimum will have more open water vulnerable to a quick refreeze. I guess there is no really good way of looking at it.

RoxTheGeologist

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Re: 2018 sea ice area and extent data
« Reply #1867 on: October 10, 2018, 08:40:15 PM »

Yes, one would think more open water at high latitudes would freeze faster as temperatures drop in the perpetual night. That's clearly not the case now.

So is it that the open water is warm and creating clouds and insulating the Arctic from heat loss?

If it is, it's a bit like putting a blanket over the heat exchanger on the earth's AC system.



Ned W

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Re: 2018 sea ice area and extent data
« Reply #1868 on: October 10, 2018, 08:49:36 PM »
I was inclined to disagree with Oren and stick with my own suggestion, but I now think Oren is right, based on some analysis of correlations.  So I would go with Juan C. Garcia's version of the bar chart, rather than my own.

Juan C. García

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Re: 2018 sea ice area and extent data
« Reply #1869 on: October 11, 2018, 01:17:50 AM »
We can do the graph in different ways, but it is impressive the low increase that 2018 has on the last 19 days.
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.

Ned W

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Re: 2018 sea ice area and extent data
« Reply #1870 on: October 11, 2018, 01:25:48 AM »
Thank you.  I think that's the right way to look at this.

Juan C. García

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Re: 2018 sea ice area and extent data
« Reply #1871 on: October 11, 2018, 05:42:01 AM »
[ADS-NIPR-JAXA] ASI Extent.

October 10th, 2018: 5,045,380 km2, an increase of 77,603 km2
October 10th on 2010's Average: 5,677,707 km2, an increase of 88,971 km2
[2010's Average] - [2008]: 632,327 km2.
2018 is the 2nd lowest on record.
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.

Jim Pettit

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Re: 2018 sea ice area and extent data
« Reply #1872 on: October 11, 2018, 12:42:51 PM »
Yesterday was the 15th consecutive day--and 26th out of the last 30--to see a JAXA Arctic sea ice change below the 10-year (2008-2017) average for the date. The average cumulative extent change for those 30 days has been +1.39M km2; this year it changed just +426k over the period, meaning in only one month 2018 has departed from the average by a pretty impressive -958k.

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Re: 2018 sea ice area and extent data
« Reply #1873 on: October 11, 2018, 01:01:58 PM »
That's good for 2019. I'll add 500k to Rob Dekker's estimates for next September, unless a extremely low FDD comes as happened in the last three Winters

magnamentis

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Re: 2018 sea ice area and extent data
« Reply #1874 on: October 11, 2018, 01:49:02 PM »
That's good for 2019. I'll add 500k to Rob Dekker's estimates for next September, unless a extremely low FDD comes as happened in the last three Winters

i disagree that this is good for anything including next year, this is kind of jumping to conclusions while thoughts are free of course ;)

keep in mind that the entire globe is warming and the oceans more and more will release some of the stored heat. further i don't think that we can predict anything next year and certainly not based on this.

much more i think that ever less thick multi-year ice and current export of some of the reminder will not do any good for the future and that is much closer to physical some facts IMO, but still does not allow to predict next years minimum and then 500k, really?


Sterks

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Re: 2018 sea ice area and extent data
« Reply #1875 on: October 11, 2018, 04:01:02 PM »
Magnamentis, of course I am jumping into conclusions and I am giving arbitrary numbers, but actually my intention behind a very poorly simplistic comment, was to convey an opinion that late refreeze negative feedback is, by now, most probably substantial (it’s continuously dark over those big expanses of water where winds have stirred waters and prevented refreeze for many days), but that given the succesion of warm winters, the overall heat loss probably be reduced to not significant.

gerontocrat

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Re: 2018 sea ice area and extent data
« Reply #1876 on: October 11, 2018, 05:57:39 PM »
JAXA ARCTIC EXTENT 5,045,380 km2(October 10, 2018)

Normal service may be gradually returning, in bits  -

- Extent increase a less than average 78k km2,
- Extent is 711 k  (12.4 %) below the 2010's average extent on this date,
- Extent is 861 k (14.6 %) below 2017 on this date.
- freezing to date from minimum is 853k (59.2%) less than the 10 year average extent gain,
- on average 14.5% (1/7th)of the increase in extent is done.

An extra line in the table based on average extent increase in the last 5 years has been added. This is because extent gain in 2012-13 was so large (rebound from record low minimum) that it distorts the average. The outcome from using the 10 year average extent gain from now is a maximum of 13.48 million km2 (400k < 2017). Using the previous 5 years's average extent gain, the resulting maximum is 13.11 million km2, some 770,000 km2 less than the 2017 record low maximum of 13.88 million km2. 

From the GFS maps it looks like North of 80 will go through a cold patch Friday to Sunday, but return to strong +ve temp anomalies by Monday. The GFs maps also indicate that overall the Arctic is going to stay at above average temperatures, the +ve anomaly approaching 5 degrees celsius by mid-week, i.e. if temperature has anything to do with it the outlook is for slow extent increase for the next 5 days and perhaps beyond.

Perhaps when this relatively warm period ends, extent gain will rebound very strongly. But maybe the delay in freezing will also reduce thickening of the ice. There is a good chance that in a week or so 2018 extent will be at a record low, which is a surprise (at least to me).

ps: The opposite is happening in the Antarctic - melting has barely started, very slowly underway.

pps: postings will be erratic while I dump microsoft office for "libre". (Next year dumping Windows - microsoft nearly lost my data for me - paying Microsoft licence fees is like voting Republican or for Brexit  - volunteering for grief).
« Last Edit: October 11, 2018, 06:03:30 PM by gerontocrat »
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Dharma Rupa

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Re: 2018 sea ice area and extent data
« Reply #1877 on: October 11, 2018, 06:00:39 PM »
JAXA ARCTIC EXTENT 5,045,380 km2(October 10, 2018)

So good to have you back!

etienne

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Re: 2018 sea ice area and extent data
« Reply #1878 on: October 11, 2018, 06:26:13 PM »
We can do the graph in different ways, but it is impressive the low increase that 2018 has on the last 19 days.
Thank you very much for the graphs. They are very interesting. I also like most the version starting September 20th for all years.
That the average of the 80', 90', 2000' always gets higher would confirm Oren's point that a reduced minimum increases the probability of a faster refreeze, but this doesn't work anymore for  2010'. Furthermore 2007 and 2012 are under the 2010' average gain, but 2015 has a very high gain.

Stephan

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Re: 2018 sea ice area and extent data
« Reply #1879 on: October 11, 2018, 07:40:12 PM »
Welcome back, gerontocrat. I missed your postings the last days...
It is too late just to be concerned about Climate Change

FishOutofWater

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Re: 2018 sea ice area and extent data
« Reply #1880 on: October 11, 2018, 08:28:27 PM »
More open water would lose more heat to the atmosphere during the dark months if clear skies allowed radiational cooling. So far, that has not been the case. Moreover, warm water has been pouring into the Arctic from the Pacific like we have never seen before while ice and fresh water are being pushed out through the Fram and the CAA at a higher than normal rate.

All in all, this looks like the Arctic is being "Atlantified" and "Pacified". This bodes ill for sea ice.

psymmo7

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Re: 2018 sea ice area and extent data
« Reply #1881 on: October 11, 2018, 11:48:27 PM »
Hi Gerontocrat,
so good to have you back - I missed your daily data

Dharma Rupa

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Re: 2018 sea ice area and extent data
« Reply #1882 on: October 11, 2018, 11:51:03 PM »
More open water would lose more heat to the atmosphere during the dark months if clear skies allowed radiational cooling. So far, that has not been the case. ...

Open water also means more evaporation and more water vapor.

Archimid

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Re: 2018 sea ice area and extent data
« Reply #1883 on: October 12, 2018, 12:20:32 AM »
I think more heat is indeed being transferred from the ocean to the atmosphere, but:

1. There is more heat and energy available from in the open oceans.
2. Extra heat is imported into the arctic from the surrounding warmer oceans.
3. The humid cloudy Arctic is interfering with radiation back to space.

Once all this extra heat gets irradiated out to space refreeze will begin with strength.

I'm very curious about the Chukchi and the Bering this year.
I am an energy reservoir seemingly intent on lowering entropy for self preservation.

Juan C. García

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Re: 2018 sea ice area and extent data
« Reply #1884 on: October 12, 2018, 05:51:05 AM »
[ADS-NIPR-JAXA] ASI Extent.

October 11th:
   2018: 5,182,196 km2, an increase of 136,816 km2
   2010's Average: 5,779,683 km2, an increase of 101,977 km2

2018 is the 3rd lowest on record.
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.

gerontocrat

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Re: 2018 sea ice area and extent data
« Reply #1885 on: October 12, 2018, 06:12:54 AM »
JAXA ARCTIC EXTENT 5,182,196 km2(October 11, 2018)

- Extent increase a GREATER than average 137k km2,
- Extent is 672 k  (11.5 %) below the 2010's average extent on this date,
- Extent is 806 k (13.5 %) below 2017 on this date.
- freezing to date from minimum is 825k (53.2%) less than the 10 year average extent gain,
- on average 15.6% of the increase in extent is done.

An extra line in the table based on average extent increase in the last 5 years has been added. This is because extent gain in 2012-13 was so large (rebound from record low minimum) that it distorts the average. The outcome from using the 10 year average extent gain from now is a maximum of 13.51 million km2 (370k < 2017). Using the previous 5 years's average extent gain, the resulting maximum is 13.15 million km2, some 730,000 km2 less than the 2017 record low maximum of 13.88 million km2. 

From the GFS maps it looks like North of 80 will go through a cold patch  to Sunday, but return to strong +ve temp anomalies by Monday. Is this the cold needed to kick-start strong freezing? On the other hand GFs maps also indicate that overall the Arctic is going to stay at above average temperatures, the +ve anomaly at amaximum of around 4.5 degrees celsius by mid-week and around + 4 celsius after that.

Perhaps extent gain will continue to rebound very strongly. But maybe the delay in freezing will also reduce thickening of the ice. There is a still a good chance that in a week or so 2018 extent will be at a record low, which is a surprise (at least to me).

ps: The opposite is happening in the Antarctic - melting has barely started, very, very slowly underway.
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Pmt111500

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Re: 2018 sea ice area and extent data
« Reply #1886 on: October 12, 2018, 06:13:17 AM »
If that's not an errorenous measurement, "The stall season" would then be ending about tomorrow. Low 60s°F highs predicted here on locations today/tomorrow so no snow here yet.
Cooling the outside by heat pump.

Juan C. García

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Re: 2018 sea ice area and extent data
« Reply #1887 on: October 12, 2018, 07:09:30 AM »
If that's not an errorenous measurement, "The stall season" would then be ending about tomorrow. Low 60s°F highs predicted here on locations today/tomorrow so no snow here yet.

Seems that "The stall season" end today, it did not wait for tomorrow…  :)
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.

Rob Dekker

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Re: 2018 sea ice area and extent data
« Reply #1888 on: October 12, 2018, 10:26:44 AM »
That's good for 2019. I'll add 500k to Rob Dekker's estimates for next September, unless a extremely low FDD comes as happened in the last three Winters

Hi Sterks,
I projected 5.19 M km2 for the NSIDC September average back in early July.
https://forum.arctic-sea-ice.net/index.php/topic,103.msg162418.html#msg162418



The final NSIDC number was 4.71, so I was 480k TOO HIGH. That's 1.5 sigma off.
Much of that was caused by the bizarre failure to refreeze in the second half of September, but still..

If you would add 500k to my number you would be way out of the ballpark.

Let me also note that our collective ASIF July poll was much more accurate this year than my projection:
https://forum.arctic-sea-ice.net/index.php/topic,2340.msg162925.html
« Last Edit: October 12, 2018, 10:44:20 AM by Rob Dekker »
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gerontocrat

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Re: 2018 sea ice area and extent data
« Reply #1889 on: October 12, 2018, 06:32:21 PM »
NSIDC Total Area as at 11 October (5 day trailing average) =  3,658,522 km2

While my computer was in surgery quite an exciting time on the area front, but now returning to "normal" ? Total Area dropped by 1k in the last 6 days. It's not supposed to do that.

Total Area gain on this day 19 k. Well below average area gain, area now 695 k less than 2017 (was 325 k on 5th October).

Peripheral Seas gain       13 k, of which 8.5k in the Greenland Sea
Central Seas     gain        7 k,                                 
Other Seas       loss         1 k, (Okhotsk)
CAB Seas
Beaufort Sea                 gain    4 k
Canadian Archipelago    gain     4 k
East Siberian Sea (ESS) gain     8 k ,
Central Arctic Sea      loss    12 k, 87k in the last 7 days

Arctic temperature anomaly staying at around 4 celsius until.....? But as darkness descends temperatures drop like a stone. Freezing must take hold eventually but may very well continue to be slow. Attention switches to the pace of that freezing and where it is happening.
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gerontocrat

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Re: 2018 sea ice area and extent data
« Reply #1890 on: October 12, 2018, 07:03:58 PM »
Some AREA graphs - starting with the Atlantic Front

All late in freezing except the Greenland Sea - Fram export restarted strongly ?
"Para a Causa do Povo a Luta Continua!"
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gerontocrat

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Re: 2018 sea ice area and extent data
« Reply #1891 on: October 12, 2018, 07:31:55 PM »
More Area Graphs - Pacific End.

Bering Sea - far too early yet, it is what happens this winter that will tell us the story.
Chukchi - already showing reluctance to freeze.
ESS - only now is below the 2010's average. The next candidate for much longer ice-free periods?
Beaufort - still above the 2010's average, but now a slower than average increase in area.
"Para a Causa do Povo a Luta Continua!"
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Stephan

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Re: 2018 sea ice area and extent data
« Reply #1892 on: October 12, 2018, 07:46:14 PM »
Once again ... it's so good to have you back here.
Except for Greenland Sea almost all other seas seem to refuse growing in area, and they ought to do so now for weeks. Something is wrong, at least much delayed.
It is too late just to be concerned about Climate Change

gerontocrat

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Re: 2018 sea ice area and extent data
« Reply #1893 on: October 12, 2018, 08:14:37 PM »
Canadian Archiplelago, Hudson Bay & Baffin.
Three seas that in theory should be freezing up - because Canada has been really cold. But are they? Not really.

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GoSouthYoungins

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Re: 2018 sea ice area and extent data
« Reply #1894 on: October 12, 2018, 08:25:49 PM »
thank you. great stuff!

The next 2 months will be extremely telling regarding the extent of Atlantification and Pacification. So far, it looks very bad; paradigm-shift bad.
big time oops

gerontocrat

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Re: 2018 sea ice area and extent data
« Reply #1895 on: October 12, 2018, 08:55:45 PM »
And
- two seas outside and south of the Arctic - Okhotsk & St Lawrence - too early to say.
Finally
- The Big Beast - The Central Arctic Sea. Suddenly this sea looks vulnerable when it should be closing up into a solid cap (see Univ Bremen sea ice concentration).
- The Total Arctic Area (all 14 seas). If this had happened a month earlier what a kerfuffle there would have been.
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Jontenoy

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Re: 2018 sea ice area and extent data
« Reply #1896 on: October 12, 2018, 09:19:27 PM »
'Arctic temperature anomaly staying at around 4 celsius until.....? But as darkness descends temperatures drop like a stone. Freezing must take hold eventually but may very well continue to be slow. Attention switches to the pace of that freezing and where it is happening'

Great data as usual Gerontocrat. Given the very slanted insolation, there is surely very little solar heat input at this time of year. It would be interesting to see the heat anomoly of the water down to 30 metres and I suspect this is the main culprit in the late refreeze

gerontocrat

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Re: 2018 sea ice area and extent data
« Reply #1897 on: October 12, 2018, 11:30:02 PM »
'Arctic temperature anomaly staying at around 4 celsius until.....? But as darkness descends temperatures drop like a stone. Freezing must take hold eventually but may very well continue to be slow. Attention switches to the pace of that freezing and where it is happening'

Great data as usual Gerontocrat. Given the very slanted insolation, there is surely very little solar heat input at this time of year. It would be interesting to see the heat anomaly of the water down to 30 metres and I suspect this is the main culprit in the late refreeze
The first image below shows a +ve temp anomaly for the Arctic of 5.1 degrees celsius, which you don't see that often, especially when GFS indicates that well over +4 is set for the 10 days. But the second image shows temps well below that needed for freezing over most of the Arctic. So I agree, I think it must be the heat store in the seas. When will that store be exhausted?
"Para a Causa do Povo a Luta Continua!"
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pauldry600

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Re: 2018 sea ice area and extent data
« Reply #1898 on: October 13, 2018, 12:41:05 AM »
Sea stores heat for a month or two.

This refreeze season I think will be slow to get going but will probably end up close to min max next year.

It seems that the minimum and maximum dates are now only 2 eventful days in 365 eventful days

Sterks

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Re: 2018 sea ice area and extent data
« Reply #1899 on: October 13, 2018, 12:44:55 AM »
The final NSIDC number was 4.71, so I was 480k TOO HIGH. That's 1.5 sigma off.
Much of that was caused by the bizarre failure to refreeze in the second half of September, but still..

If you would add 500k to my number you would be way out of the ballpark.

Let me also note that our collective ASIF July poll was much more accurate this year than my projection:
https://forum.arctic-sea-ice.net/index.php/topic,2340.msg162925.html
However, you in fact noted  in that post, that you felt your model was falling on the high side this year.I take your model with the post-filter of common sense and gut feeling.

The 500k is a symbolic number meaning that there will probably be some repercussion of this late refreeze on the next season, in the form of less heat available, obviously, but this effect is almost impossible to identify with the lack of 4D data of ocean heat in the Arctic, much less to quantify, and probably not significant if the Arctic winter is as warm as last three years or if Bering or Atlantic ocean heat fluxes play a role.