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gerontocrat

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Re: 2020 Sea ice area and extent data
« Reply #1400 on: August 30, 2020, 10:55:32 AM »
JAXA Extent - a bit more

Minima Table
- If extent loss stopped on this day, extent would be the 4th lowest minimum in the satellite record.
- A further 100k extent losses will make 2020 indisputably 2nd lowest.
- But it would require 0.88 million km2 of further extent losses to make 2020 #1, i.e. lowest in the satellite record.

Average extent loss from this date to minimum is 250k, with on average just 16 days to minimum.

Arc-PLUME The range of outcomes from remaining melt in the last 10 years is now just 260k.
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Glen Koehler

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Re: 2020 Sea ice area and extent data
« Reply #1401 on: August 30, 2020, 03:12:28 PM »
   Thanks Gerontocrat not only for the data but for the concise narrative summaries that provide context and meaning to the numbers.  But I have a question.  In previous message (https://forum.arctic-sea-ice.net/index.php/topic,2975.msg283986.html#msg283986 with remaining melt at the 10 year average, the 2020 minimum JAXA Extent table value is 3.70.  The chart in message above shows that by following the 10 year average melt, the 2020 minimum JAXA Extent bottoms out at about 3.775.  Such a small difference does not change the future of human civilization on the planet, but it just makes me wonder why the chart value does not match the table value.
« Last Edit: August 30, 2020, 03:27:25 PM by Glen Koehler »

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Re: 2020 Sea ice area and extent data
« Reply #1402 on: August 30, 2020, 03:26:01 PM »
NSIDC daily extent

Today's 1-day change was −83

7-day average:  (4365 − 4577) / 7  =  −30
14-day average: (4365 − 5200) / 14  =  −60

2020-08-15  5.200    +63
2020-08-16  5.069  −131
2020-08-17  4.957  −112
2020-08-18  4.930    −27
2020-08-19  4.816  −114
2020-08-20  4.704  −112
2020-08-21  4.630    −74
2020-08-22  4.577    −53
2020-08-23  4.552    −25
2020-08-24  4.492    −60
2020-08-25  4.429    −63
2020-08-26  4.427      −2
2020-08-27  4.363    −64
2020-08-28  4.448    +85
2020-08-29  4.365    −83

Steven

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Re: 2020 Sea ice area and extent data
« Reply #1403 on: August 30, 2020, 04:15:30 PM »
But I have a question.  In previous message (https://forum.arctic-sea-ice.net/index.php/topic,2975.msg283986.html#msg283986 with remaining melt at the 10 year average, the 2020 minimum JAXA Extent table value is 3.70.  The chart in message above shows that by following the 10 year average melt, the 2020 minimum JAXA Extent bottoms out at about 3.775.  Such a small difference does not change the future of human civilization on the planet, but it just makes me wonder why the chart value does not match the table value.

This is to be expected.  The 10-year average trajectory is an unrealistically smooth curve.  Individual years fluctuate around that, with some peaks and troughs and with the minimum in one of the troughs.

Juan C. García

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Re: 2020 Sea ice area and extent data
« Reply #1404 on: August 30, 2020, 04:35:18 PM »
   Thanks Gerontocrat not only for the data but for the concise narrative summaries that provide context and meaning to the numbers.  But I have a question.  In previous message (https://forum.arctic-sea-ice.net/index.php/topic,2975.msg283986.html#msg283986 with remaining melt at the 10 year average, the 2020 minimum JAXA Extent table value is 3.70.  The chart in message above shows that by following the 10 year average melt, the 2020 minimum JAXA Extent bottoms out at about 3.775.  Such a small difference does not change the future of human civilization on the planet, but it just makes me wonder why the chart value does not match the table value.

I think I will answer this one.

It is different to first calculate the minimum of each year and then make the average, against first calculate the average of the day and then calculate the minimum. This is because the min of each year happens on different days.

ADS (JAXA) calculates the average of the day and Gerontocrat's chart is based on this calculation. The 2020 min will be 3.78M km2, while in Gerontocrat's table he first find the min of each year and then makes the average. The result is 3.70M km2.
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: 2020 Sea ice area and extent data
« Reply #1405 on: August 30, 2020, 04:59:54 PM »
Thanks Juan - I am getting brain-fade.  There are so many ways to calculate that which probably won't happen anyway. Somehow the Arctic never seems to do what it's told to do.
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gerontocrat

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Re: 2020 Sea ice area and extent data
« Reply #1406 on: August 30, 2020, 05:05:13 PM »
NSIDC graphs... Central Arctic Sea

The ice edge heading north on the Atlantic Front continues to reduce sea ice area and extent.
Ice area now below 2 million km2.
"Para a Causa do Povo a Luta Continua!"
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gerontocrat

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Re: 2020 Sea ice area and extent data
« Reply #1407 on: August 30, 2020, 05:19:08 PM »
NSIDC Graphs..... Laptev & the ESS

The current push of the ice towards the Pacific lloks like its is completing the demolition of the small amount of remaining ice in the Laptev Sea.

If the push continues, maybe something similar in the ESS? (Currently sea ice extent loss stalled, area rebounding)
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gerontocrat

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Re: 2020 Sea ice area and extent data
« Reply #1408 on: August 30, 2020, 05:26:42 PM »
NSIDC Graphs - Greenland & the CAA

The cyclone centred just south of Svalbard looks like it is sending ice into the Greenland Sea. My guess is that this ice is doomed to die pdq.

Will the prevailing winds get the Garlic Press into full swing? Or will it just start freezing? or both?
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gerontocrat

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Re: 2020 Sea ice area and extent data
« Reply #1409 on: August 30, 2020, 05:28:33 PM »
NSIDC Graphs - the Beaufort

Sea ice area and extent losses have stalled.

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glennbuck

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Re: 2020 Sea ice area and extent data
« Reply #1410 on: August 30, 2020, 08:10:36 PM »
NSIDC Daily Area: August 29

Arctic Sea ice area: 2,703,777 million km^2.

Change from yesterday: Area loss of 44,008 km^2

(2020) NSIDC: Area daily: 2.703               NSIDC: Extent daily: 4.365


NSIDC: September daily area minimum     NSIDC: September daily extent minimum

(2012) 2.241                                             : 3.340  <<  Sep  16
(2016) 2.477                                             : 4.145         Sep   7               
(2011) 2.940                                             : 4.333         Sep   8
(2019) 2.960                                             : 4.166         Sep 17
(2017) 3.020                                             : 4.635         Sep 13
(2007) 3.050                                             : 4.155         Sep 18
(2008) 3.120                                             : 4.586         Sep 19
(2015) 3.160                                             : 4.387         Sep   8
(2018) 3.270                                             : 4.630         Sep 21
« Last Edit: August 31, 2020, 05:45:20 PM by glennbuck »

Juan C. García

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Re: 2020 Sea ice area and extent data
« Reply #1411 on: August 31, 2020, 05:32:02 AM »
[ADS NIPR VISHOP (JAXA)] Arctic Sea Ice Extent.

August 30th, 2020:
     3,995,083 km2, a drop of -63,462 km2.
     2020 is 2nd lowest on record.
     Highlighted 2020 & the 4 years with a daily lowest min in Sept. (2012, 2019, 2016 & 2007).
     In the graph are today's 10 lowest years.
     Source: https://ads.nipr.ac.jp/vishop/#/extent

P.S. 2020 became the third lowest minimum on record today. There are still about two weeks left until the 2020 melting season ends.
« Last Edit: August 31, 2020, 05:47:20 AM 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.

gerontocrat

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Re: 2020 Sea ice area and extent data
« Reply #1412 on: August 31, 2020, 10:33:07 AM »
JAXA ARCTIC SEA ICE EXTENT:  3,995,083 KM2 as at 30-Aug-2020

- Extent loss on this day 63k, 26 k more than the average loss on this day (of the last 10 years) of 37k,
- Extent loss from maximum on this date is 10,453 k, 819 k, 8.5% more than the 10 year average of 9,634 k.
- Extent is at position #2 in the satellite record
- Extent is  307 k LESS than 2019,
- Extent is  307 k LESS than 2016,
- Extent is  457 k MORE than 2012
- Extent is  447 k LESS than 2007
_____________________________________________
On average 96.8% of melting from maximum to minimum done, and 15 days to minimum

Projections. (Table JAXA-Arc1)

Average remaining melt (of the last 10 years) would produce a minimum in Sept 2020 of 3.68 million km2, 0.50 million km2 above the 2012 minimum of 3.18 million km2.

For a record low, remaining melt needs to be  158.0% or more above average.
For the 2020 minimum to be above the 2019 minimum of 3.96 million km2, remaining melt needs to be  88.9% or more below the previous 10 years average remaining melt.
_____________________________________________
Spare a crocodile tear for 2016 - no longer in the top 3 - not even a bronze medal.
How low will it go?

______________________________
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gerontocrat

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Re: 2020 Sea ice area and extent data
« Reply #1413 on: August 31, 2020, 03:20:12 PM »
It is 14:18 BST and no NSIDC data. What a time for no data!

I'm off-line.
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glennbuck

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Re: 2020 Sea ice area and extent data
« Reply #1414 on: August 31, 2020, 05:48:02 PM »
NSIDC Daily Area: August 30

Arctic Sea ice area: 2,656,970 million km^2.

Change from yesterday: Area loss of 46,807 km^2

(2020) NSIDC: Area daily: 2.656               NSIDC: Extent daily: 4.260


NSIDC: September daily area minimum     NSIDC: September daily extent minimum

(2012) 2.241                                             : 3.340  <<  Sep  16
(2016) 2.477                                             : 4.145         Sep   7               
(2011) 2.940                                             : 4.333         Sep   8
(2019) 2.960                                             : 4.166         Sep 17
(2017) 3.020                                             : 4.635         Sep 13
(2007) 3.050                                             : 4.155         Sep 18
(2008) 3.120                                             : 4.586         Sep 19
(2015) 3.160                                             : 4.387         Sep   8
(2018) 3.270                                             : 4.630         Sep 21
« Last Edit: August 31, 2020, 09:07:05 PM by glennbuck »

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Re: 2020 Sea ice area and extent data
« Reply #1415 on: August 31, 2020, 09:05:09 PM »
NSIDC daily extent

Today's 1-day change was −105

7-day average:  (4260 − 4552) / 7  =  −42
14-day average: (4260 − 5069) / 14  =  −58

2020-08-16  5.069
2020-08-17  4.957  −112
2020-08-18  4.930    −27
2020-08-19  4.816  −114
2020-08-20  4.704  −112
2020-08-21  4.630    −74
2020-08-22  4.577    −53
2020-08-23  4.552    −25
2020-08-24  4.492    −60
2020-08-25  4.429    −63
2020-08-26  4.427      −2
2020-08-27  4.363    −64
2020-08-28  4.448    +85
2020-08-29  4.365    −83
2020-08-30  4.260  −105

gerontocrat

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Re: 2020 Sea ice area and extent data
« Reply #1416 on: August 31, 2020, 11:10:23 PM »
So I think I have an evening off and then find that NSIDC posted the data a couple of hours later than usual....

NSIDC Total Area as at 30-Aug-2020 (5 day trailing average) 2,715,948 KM2         
         
Total Area         
 2,715,948    km2      
-531,337    km2   <   2010's average.
-279,404    km2   <   2019
-1,489,456    km2   <   2000's average.
         
Total Change   -28    k   loss
Peripheral Seas   -2    k   loss
Central Seas___   -26    k   loss
         
Peripheral Seas         
Okhotsk______    0    k   gain
Bering _______   -0    k   loss
Hudson Bay___   -1    k   loss
Baffin  Bay____   -1    k   loss
St Lawrence___    -    k   loss
Greenland____    0    k   gain
Barents ______   -0    k   loss
         
Central Arctic  Ocean Seas         
Chukchi______    0    k   gain
Beaufort_____   -4    k   loss
CAA_________   -1    k   loss
East Siberian__    10    k   gain
Central Arctic_   -30    k   loss
Laptev_______   -1    k   loss
Kara_________   -1    k   loss
         
Sea ice area loss on this day 28 k, 1 k more than the 2010's average loss of 27 k         
         
- 2020 area is at position #3 in the satellite record.         
- 2020 Area is 531 k less than the 2010's average         
- 2020 Area is 1,489 k less than the 2000's average         
- 2020 Area is 24 k more than 2016         
- 2020 Area is 279 k less than 2019          
- 2020 Area is 199 k more than 2012         
___________________________________________         
NSIDC Total EXTENT as at 30-Aug-2020 (5 day trailing average) 4,356,729 KM2         
         
NSIDC Sea ice EXTENT loss on this day 34 k, 1 k less than the 2010's average loss of 35k         
         
- 2020 EXTENT is at position #2 in the satellite record.         
- 2020 EXTENT is 507 k less than the 2010's average         
- 2020 EXTENT is 1,551 k less than the 2000's average         
- 2020 EXTENT is 223 k less than 2016         
- 2020 EXTENT is 265 k less than 2019          
- 2020 EXTENT is 576 k more than 2012

___________________________________________
Will NSIDC data follow JAXA with above average sea ice area and extent losses?   
___________________________________________         
Note: Click once on each image to see it full-size         
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Juan C. García

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Re: 2020 Sea ice area and extent data
« Reply #1417 on: September 01, 2020, 05:31:54 AM »
[ADS NIPR VISHOP (JAXA)] Arctic Sea Ice Extent.

August 31st, 2020:
     3,943,313 km2, a drop of -51,770 km2.
     2020 is 2nd lowest on record on this date.
     Highlighted 2020 & the 4 years with a daily lowest min in Sept. (2012, 2019, 2016 & 2007).
     In the graph are today's 10 lowest years.
     Source: https://ads.nipr.ac.jp/vishop/#/extent

P.S. 2020 became the second lowest minimum on record today. There are still about two weeks left until the 2020 melting season ends.
« Last Edit: September 01, 2020, 05:45:39 AM 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.

Ktb

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Re: 2020 Sea ice area and extent data
« Reply #1418 on: September 01, 2020, 06:24:51 AM »
Semimonthly BOE evaluation

As of August 31st, extent is 3,943,313 km2. With on average 13 days to go until the end of the melt season on September 13th, we now require a daily drop of -226,409 km2 for a BOE to occur. (See Attachment 1).

Total extent loss so far this season is -10,504,328 km2. This has resulted in the current season average daily drop of -58,035 km2. Since the year 2007, this is the 4th fastest average daily loss from maximum to August 31st (2007-2020). (See Attachment 2).
--- If the season ended today, total extent loss from maximum to minimum would be 2nd highest since 2007, behind only 2012. ---

Total extent loss from maximum to August 31st is 2nd highest on record in the post-2007 era, behind only 2012. (See Attachment 3).

Looking only at the month of August, 2020 lost -1,813,071 km2, averaging -58,486 km2 per day. Losing 5,000 km2 more than the average of -1,808,351 km2 in the post-2007 era, some ~700km2 less than 2012 lost in August. (See Attachment 4).


Finally, the 2007-2019 average ice loss for September 1st to maximum is -239,348 km2, with 2010 losing the most at -475,120 km2 and 2015 losing the least at -109,577 km2. Giving us a range for the minimum of 3,468,193 and 3,833,736 km2 respectively.
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Ktb

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Re: 2020 Sea ice area and extent data
« Reply #1419 on: September 01, 2020, 06:27:54 AM »
And for comparisons to other years:

The following attachment is for actual previous years daily average melt from September 1st to their respective minimums. (Attachment 1).

The following section is for what the previous years would have needed for a BOE to occur: From September 1st to each years respective minimum, our current BOE requirement of -226,409 km2 is the 5th least negative value, of which 2012 is the leader. (See attachment 2).
These numbers will vary depending on the date of 2020s minimum, with extra days decreasing this average.
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grixm

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Re: 2020 Sea ice area and extent data
« Reply #1420 on: September 01, 2020, 08:36:09 AM »
Semimonthly BOE evaluation
[..]

I have a question regarding the "required average" numbers. It looks like these are just remaining melt divided by average remaining melt days?
If so, I think it would be very beneficial to add a column with "weighed" numbers too, i.e the current number multiplied by the average melt for this date divided by the average melt for every date during the melting season. So that the required average is higher during peak melting season, but lower during early and late season. I think this would more accurately reflect whether we are actually on pace or not.

For example, during the peak of the melting season, we saw many days where we were "on pace" because the daily melt was higher than the required average. But just looking at the chart it was pretty obvious that we were not actually on pace, that's because a BOE would require keeping the same melt rate even in April, May, September etc, as in June, July, August, which is unrealistic.

Ktb

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Re: 2020 Sea ice area and extent data
« Reply #1421 on: September 01, 2020, 09:06:39 AM »
New required average is current extent minus extent necessary to cross 1,000,000 km2 threshold divided by number of days remaining in an average melt season.

As this melt season is essentially over, I can look in to making some changes for the 2021 season. I do not keep records during the freezing season. Am happy to make additions to my excel tables.

Additionally, while individual days may be on pace that does not mean the season as a whole is on pace. The on pace column keeps track of the season as a whole, not individual days. I agree it is not perfect, however we do expect lower melt in the earliest and latest months of the melt season, and stronger melt in the middle. For a BOE to occur at some point the strongest melt months will outweigh/outaverage the weaker melt months.
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gerontocrat

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Re: 2020 Sea ice area and extent data
« Reply #1422 on: September 01, 2020, 11:24:06 AM »
JAXA ARCTIC SEA ICE EXTENT:  3,943,313 KM2 as at 31-Aug-2020

- Extent loss on this day 52k, 17 k more than the average loss on this day (of the last 10 years) of 35k,
- Extent loss from maximum on this date is 10,504 k, 835 k, 8.6% more than the 10 year average of 9,669 k.
- Extent is at position #2 in the satellite record
- Extent is  316 k LESS than 2019,
- Extent is  299 k LESS than 2016,
- Extent is  434 k MORE than 2012
- Extent is  471 k LESS than 2007
_____________________________________________
On average 97.2% of melting from maximum to minimum done, and 14 days to minimum

Projections. (Table JAXA-Arc1)

Average remaining melt (of the last 10 years) would produce a minimum in Sept 2020 of 3.66 million km2, 0.48 million km2 above the 2012 minimum of 3.18 million km2.

For a record low, remaining melt needs to be  171.6% or more above average. Nah, barring a modern miracle.

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gerontocrat

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Re: 2020 Sea ice area and extent data
« Reply #1423 on: September 01, 2020, 11:57:56 AM »
JAXA... a bit more.

The minima table shows 2020 safely at 2nd lowest, and unlikely to make #1.

The Plume, however, shows that if remaining melt matches 2010, final minimum will be just below 3.5 million km2. If this happens, many on the ASIF will be gnashing their teeth as they tear up their betting slips. A few others will be wearing smug smiles (but not me).

I also attach the monthly average graph for August. 2020 was the 2nd lowest monthly average. At 4.8 million km2, it was just over 200k, about 2 1/2 years, below the linear trend

The last graph is the September averages, the figure for 2020 an estimate that assumes remaining melt and late September freeze will be at the average (of the last 10 years). Of note is that, at 3.88 million km2, it would be only the second time the monthly average was below 4 million km2.
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glennbuck

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Re: 2020 Sea ice area and extent data
« Reply #1424 on: September 01, 2020, 02:32:44 PM »
NSIDC Daily Area: August 31

Arctic Sea ice area: 2,753,319 million km^2.

Change from yesterday: Area gain of 96,349 km^2

(2020) NSIDC: Area daily: 2.753               NSIDC: Extent daily: 4.200


NSIDC: September daily area minimum     NSIDC: September daily extent minimum

(2012) 2.241                                             : 3.340  <<  Sep  16
(2016) 2.477                                             : 4.145         Sep   7               
(2011) 2.940                                             : 4.333         Sep   8
(2019) 2.960                                             : 4.166         Sep 17
(2017) 3.020                                             : 4.635         Sep 13
(2007) 3.050                                             : 4.155         Sep 18
(2008) 3.120                                             : 4.586         Sep 19
(2015) 3.160                                             : 4.387         Sep   8
(2018) 3.270                                             : 4.630         Sep 21
« Last Edit: September 01, 2020, 09:57:58 PM by glennbuck »

Alphabet Hotel

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Re: 2020 Sea ice area and extent data
« Reply #1425 on: September 01, 2020, 02:49:48 PM »
NSIDC daily extent

Today's 1-day change was −60

7-day average:  (4200 − 4492) / 7  =  −42
14-day average: (4200 − 4957) / 14  =  −54

2020-08-17  4.957
2020-08-18  4.930    −27
2020-08-19  4.816  −114
2020-08-20  4.704  −112
2020-08-21  4.630    −74
2020-08-22  4.577    −53
2020-08-23  4.552    −25
2020-08-24  4.492    −60
2020-08-25  4.429    −63
2020-08-26  4.427      −2
2020-08-27  4.363    −64
2020-08-28  4.448    +85
2020-08-29  4.365    −83
2020-08-30  4.260  −105
2020-08-31  4.200    −60

Shared Humanity

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Re: 2020 Sea ice area and extent data
« Reply #1426 on: September 01, 2020, 03:27:50 PM »

August 31, 2020:
     3,943,313 km, a drop of -51,770 km2.
     2020 is 2nd lowest on record on this date.

P.S. 2020 became the second lowest minimum on record today. There are still about two weeks left until the 2020 melting season ends.

2020 will continue to close the gap with 2012 but fail to record a new minimum IMHO.

Macalaga

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Re: 2020 Sea ice area and extent data
« Reply #1427 on: September 01, 2020, 03:46:47 PM »
Semimonthly BOE evaluation
[..]

I have a question regarding the "required average" numbers. It looks like these are just remaining melt divided by average remaining melt days?
If so, I think it would be very beneficial to add a column with "weighed" numbers too, i.e the current number multiplied by the average melt for this date divided by the average melt for every date during the melting season. So that the required average is higher during peak melting season, but lower during early and late season. I think this would more accurately reflect whether we are actually on pace or not.

For example, during the peak of the melting season, we saw many days where we were "on pace" because the daily melt was higher than the required average. But just looking at the chart it was pretty obvious that we were not actually on pace, that's because a BOE would require keeping the same melt rate even in April, May, September etc, as in June, July, August, which is unrealistic.

I think you are on the right track here. Probably best done in parallel with what you are currently doing.

What might be interesting is to try to model what a BOE year might look like by taking for instance the five lowest minimum years and then stretching this to the BOE threshold of 1 million square km. You could then have a reasonable model for required ice loss in each month based on the historical record. Each year as we get closer, the model should automatically adjust with the addition of data from record breaking or near record minimums.

Ktb

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Re: 2020 Sea ice area and extent data
« Reply #1428 on: September 01, 2020, 04:10:37 PM »
How can you call the melt season as over 2-3 weeks ahead of time with even short term forecasts speaking another language?

You're misreading. I said the melt season is essentially over. At most we lose another ~480k km (based on historical numbers). At most I post one more semi-monthly update (September 15th, again based on historical dates of minimum). I do not think the melt season is over. I know it is not over. And I have been laughing every time somebody in the melt season thread says that we will have an August minimum or that a one day increase in area on Sept 1st means an early minimum.

I think you are on the right track here. Probably best done in parallel with what you are currently doing.

What might be interesting is to try to model what a BOE year might look like by taking for instance the five lowest minimum years and then stretching this to the BOE threshold of 1 million square km. You could then have a reasonable model for required ice loss in each month based on the historical record. Each year as we get closer, the model should automatically adjust with the addition of data from record breaking or near record minimums.

Relatively easy to add things like this. And I love to make bigger, more complex spreadsheets anyway.
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gerontocrat

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Re: 2020 Sea ice area and extent data
« Reply #1429 on: September 01, 2020, 04:49:38 PM »
NSIDC Total Area as at 31-Aug-2020 (5 day trailing average) 2,720,679 KM2         
         
Total Area         
 2,720,679    km2      
-500,761    km2   <   2010's average.
-284,441    km2   <   2019
-1,461,094    km2   <   2000's average.
         
Total Change    5    k   gain
Peripheral Seas   -1    k   loss
Central Seas___    6    k   gain
         
Peripheral Seas         
Okhotsk______    0    k   gain
Bering _______    0    k   gain
Hudson Bay___   -1    k   loss
Baffin  Bay____   -1    k   loss
St Lawrence___    -    k   loss
Greenland____   -0    k   loss
Barents ______    0    k   gain
         
Central Arctic  Ocean Seas         
Chukchi______    0    k   gain
Beaufort_____   -8    k   loss
CAA_________   -2    k   loss
East Siberian__    8    k   gain
Central Arctic_    9    k   gain
Laptev_______   -0    k   loss
Kara_________   -0    k   loss
         
Sea ice area gain on this day 5 k, 31 k different from the 2010's average loss of 26 k         
         
- 2020 area is at position #3 in the satellite record.         
- 2020 Area is 501 k less than the 2010's average         
- 2020 Area is 1,461 k less than the 2000's average         
- 2020 Area is 43 k more than 2016         
- 2020 Area is 284 k less than 2019          
- 2020 Area is 229 k more than 2012         
___________________________________________         
NSIDC Total EXTENT as at 31-Aug-2020 (5 day trailing average) 4,311,217 KM2         
         
NSIDC Sea ice EXTENT loss on this day 46 k, 6 k more than the 2010's average loss of 40k         
         
- 2020 EXTENT is at position #2 in the satellite record.         
- 2020 EXTENT is 513 k less than the 2010's average         
- 2020 EXTENT is 1,559 k less than the 2000's average         
- 2020 EXTENT is 205 k less than 2016         
- 2020 EXTENT is 286 k less than 2019          
- 2020 EXTENT is 582 k more than 2012

____________________________________
End-of-season wobbles again - area up, extent down         
___________________________________________         
Note: Click once on each image to see it full-size         
« Last Edit: September 01, 2020, 05:53:44 PM by gerontocrat »
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oren

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Re: 2020 Sea ice area and extent data
« Reply #1430 on: September 01, 2020, 05:24:19 PM »
igs and others, please don't take this thread off-topic. This thread is about area and extent data and its direct analysis, not about opinions about the melting season - for that we have the melting season thread.

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Re: 2020 Sea ice area and extent data
« Reply #1431 on: September 01, 2020, 08:13:31 PM »
NSIDC Data, a bit more..... The main story still seems to be the Central Arctic Sea and the Beaufort.

The Beaufort keeps us guessing on how low can it go so late in the season.

Central Arctic Sea Area stalled gain, but extent loss was significant.
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Juan C. García

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Re: 2020 Sea ice area and extent data
« Reply #1432 on: September 02, 2020, 05:31:18 AM »
[ADS NIPR VISHOP (JAXA)] Arctic Sea Ice Extent.

September 1st, 2020:
     3,894,998 km2, a drop of -48,315 km2.
     2020 is 2nd lowest on record on this date.
     Highlighted 2020 & the 4 years with a daily lowest min in Sept. (2012, 2019, 2016 & 2007).
     In the graph are today's 10 lowest years.
     Source: https://ads.nipr.ac.jp/vishop/#/extent
« Last Edit: September 02, 2020, 05:43:06 AM 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.

gerontocrat

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Re: 2020 Sea ice area and extent data
« Reply #1433 on: September 02, 2020, 08:30:50 AM »
JAXA ARCTIC SEA ICE EXTENT:  3,894,998 KM2 as at 01-Sep-2020

- Extent loss on this day 48k, 22 k more than the average loss on this day (of the last 10 years) of 26k,
- Extent loss from maximum on this date is 10,553 k, 858 k, 8.8% more than the 10 year average of 9,695 k.
- Extent is at position #2 in the satellite record
- Extent is  353 k LESS than 2019,
- Extent is  273 k LESS than 2016,
- Extent is  419 k MORE than 2012
- Extent is  519 k LESS than 2007
_____________________________________________
On average 97.4% of melting from maximum to minimum done, and 13 days to minimum

Projections. (Table JAXA-Arc1)

Average remaining melt (of the last 10 years) would produce a minimum in Sept 2020 of 3.64 million km2, 0.46 million km2 above the 2012 minimum of 3.18 million km2.

For a record low, remaining melt needs to be  180.4% or more above average.
Note that remaining extent loss in 2010 was 97% above the average.

_____________________________________________
A new record low still seems pretty much impossible.
But 2020 looks like narrowing substantially the yawning gap between the 2012 minimum and 2nd place.

______________________________
N.B. Click once on an image to make it full-size
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glennbuck

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Re: 2020 Sea ice area and extent data
« Reply #1434 on: September 02, 2020, 02:04:48 PM »
NSIDC Daily Area: September 1st

Arctic Sea ice area: 2,736,561 million km^2.

Change from yesterday: Area loss of 16,758 km^2

(2020) NSIDC: Area daily: 2.736               NSIDC: Extent daily: 4.004


NSIDC: September daily area minimum     NSIDC: September daily extent minimum

(2012) 2.241                                             : 3.340  <<  Sep  16
(2016) 2.477                                             : 4.145         Sep   7               
(2011) 2.940                                             : 4.333         Sep   8
(2019) 2.960                                             : 4.166         Sep 17
(2017) 3.020                                             : 4.635         Sep 13
(2007) 3.050                                             : 4.155         Sep 18
(2008) 3.120                                             : 4.586         Sep 19
(2015) 3.160                                             : 4.387         Sep   8
(2018) 3.270                                             : 4.630         Sep 21
« Last Edit: September 02, 2020, 11:30:26 PM by glennbuck »

gerontocrat

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Re: 2020 Sea ice area and extent data
« Reply #1435 on: September 02, 2020, 02:48:23 PM »
NSIDC Total Area as at 01-Sep-2020 (5 day trailing average) 2,729,638 KM2         
         
Total Area         
 2,729,638    km2      
-467,537    km2   <   2010's average.
-273,542    km2   <   2019
-1,426,252    km2   <   2000's average.
         
Total Change    9    k   gain
Peripheral Seas   -6    k   loss
Central Seas___    15    k   gain
         
Peripheral Seas         
Okhotsk______   -1    k   loss
Bering _______   -0    k   loss
Hudson Bay___   -1    k   loss
Baffin  Bay____   -1    k   loss
St Lawrence___    -    k   loss
Greenland____   -3    k   loss
Barents ______   -0    k   loss
         
Central Arctic  Ocean Seas         
Chukchi______   -0    k   loss
Beaufort_____   -14    k   loss
CAA_________   -3    k   loss
East Siberian__    4    k   gain
Central Arctic_    27    k   gain
Laptev_______   -0    k   loss
Kara_________    1    k   gain
         
Sea ice area gain on this day 9 k, 33 k different from the 2010's average loss of 24 k         
         
- 2020 area is at position #3 in the satellite record.         
- 2020 Area is 468 k less than the 2010's average         
- 2020 Area is 1,426 k less than the 2000's average         
- 2020 Area is 72 k more than 2016         
- 2020 Area is 274 k less than 2019          
- 2020 Area is 266 k more than 2012         
___________________________________________         
NSIDC Total EXTENT as at 01-Sep-2020 (5 day trailing average) 4,242,155 KM2         
         
NSIDC Sea ice EXTENT loss on this day 69 k, 29 k more than the 2010's average loss of 40k         
         
- 2020 EXTENT is at position #2 in the satellite record.         
- 2020 EXTENT is 542 k less than the 2010's average         
- 2020 EXTENT is 1,585 k less than the 2000's average         
- 2020 EXTENT is 224 k less than 2016         
- 2020 EXTENT is 323 k less than 2019          
- 2020 EXTENT is 556 k more than 2012
   
_____________________________________________
End-of-season wobbles yet again - area up, extent down a lot.
NSIDC daily extent down by 196k. Pretty much a rarity. 
Methinks the sensors and the algorithms are finding it difficult.     

Note the rebound in Central Arctic Sea area while extent continues steeply down
      
___________________________________________         
Note: Click once on each image to see it full-size         
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Juan C. García

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Re: 2020 Sea ice area and extent data
« Reply #1436 on: September 02, 2020, 03:51:29 PM »
NSIDC daily extent down by 196k. Pretty much a rarity. 
Methinks the sensors and the algorithms are finding it difficult.     

Even with the 196K km2 drop on the daily extent, the NSIDC September 1st, 2020 5-day trailing average [on Charctic graph] is 4.256M km2 on the same date, that is above of the daily minimums of 2007, 2016 and 2019. So, I like the 196K km2 daily drop that I see as a correction of the data that they have before, what I find hard to believe is that according to NSIDC, 2020 is still above these 3 minimums.
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: 2020 Sea ice area and extent data
« Reply #1437 on: September 02, 2020, 04:11:36 PM »
NSIDC Graphs - Central Arctic &  Beaufort

Just watching day by day....
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Alphabet Hotel

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Re: 2020 Sea ice area and extent data
« Reply #1438 on: September 02, 2020, 05:32:58 PM »
NSIDC daily extent

Today's 1-day change was −196

7-day average:  (4004 − 4429) / 7  =  −61
14-day average: (4004 − 4930) / 14  =  −66

2020-08-18  4.930
2020-08-19  4.816  −114
2020-08-20  4.704  −112
2020-08-21  4.630    −74
2020-08-22  4.577    −53
2020-08-23  4.552    −25
2020-08-24  4.492    −60
2020-08-25  4.429    −63
2020-08-26  4.427      −2
2020-08-27  4.363    −64
2020-08-28  4.448    +85
2020-08-29  4.365    −83
2020-08-30  4.260  −105
2020-08-31  4.200    −60
2020-09-01  4.004  −196

bosbas

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Re: 2020 Sea ice area and extent data
« Reply #1439 on: September 02, 2020, 06:01:18 PM »
Isn't that big drop in NSIDC the result of the new month and a different mask to remove non-existing coastal ice?

gerontocrat

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Re: 2020 Sea ice area and extent data
« Reply #1440 on: September 02, 2020, 06:11:34 PM »
Isn't that big drop in NSIDC the result of the new month and a different mask to remove non-existing coastal ice?
My guess is partly - but how much given recent high extent losses from JAXA is even more a pure guess I am not qualified to make.
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Juan C. García

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Re: 2020 Sea ice area and extent data
« Reply #1441 on: September 03, 2020, 05:31:01 AM »
[ADS NIPR VISHOP (JAXA)] Arctic Sea Ice Extent.

September 2nd, 2020:
     3,860,699 km2, a drop of -34,299 km2.
     2020 is 2nd lowest on record on this date.
     Highlighted 2020 & the 4 years with a daily lowest min in Sept. (2012, 2019, 2016 & 2007).
     In the graph are today's 10 lowest years.
     Source: https://ads.nipr.ac.jp/vishop/#/extent
« Last Edit: September 03, 2020, 05:48:35 AM 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.

gerontocrat

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Re: 2020 Sea ice area and extent data
« Reply #1442 on: September 03, 2020, 10:54:36 AM »
JAXA ARCTIC SEA ICE EXTENT:  3,860,699 KM2 as at 02-Sep-2020

- Extent loss on this day 34k, 11 k more than the average loss on this day (of the last 10 years) of 23k,
- Extent loss from maximum on this date is 10,587 k, 869 k, 8.9% more than the 10 year average of 9,718 k.
- Extent is at position #2 in the satellite record
- Extent is  354 k LESS than 2019,
- Extent is  229 k LESS than 2016,
- Extent is  415 k MORE than 2012
- Extent is  552 k LESS than 2007
_____________________________________________
On average 97.7% of melting from maximum to minimum done, and 12 days to minimum

Projections. (Table JAXA-Arc1)

Average remaining melt (of the last 10 years) would produce a minimum in Sept 2020 of 3.63 million km2, 0.45 million km2 above the 2012 minimum of 3.18 million km2.

For a record low, remaining melt needs to be  193.1% or more above average.
Note that remaining extent loss in 2010 was 106% above the average.
______________________________
N.B. Click once on an image to make it full-size
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gerontocrat

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Re: 2020 Sea ice area and extent data
« Reply #1443 on: September 03, 2020, 02:45:59 PM »
NSIDC Total Area as at 02-Sep-2020 (5 day trailing average) 2,731,925 KM2         
         
Total Area         
 2,731,925    km2      
-443,596    km2   <   2010's average.
-258,725    km2   <   2019
-1,397,610    km2   <   2000's average.
         
Total Change    2    k   gain
Peripheral Seas   -8    k   loss
Central Seas___    10    k   gain
         
Peripheral Seas         
Okhotsk______   -2    k   loss
Bering _______   -0    k   loss
Hudson Bay___    1    k   gain
Baffin  Bay____   -0    k   loss
St Lawrence___    -    k   loss
Greenland____   -6    k   loss
Barents ______   -0    k   loss
         
Central Arctic  Ocean Seas         
Chukchi______   -0    k   loss
Beaufort_____   -14    k   loss
CAA_________   -3    k   loss
East Siberian__    1    k   gain
Central Arctic_    25    k   gain
Laptev_______   -0    k   loss
Kara_________    0    k   gain
         
Sea ice area GAIN on this day 2 k, 24 k less than the 2010's average loss of 22 k         
         
- 2020 area is at position #3 in the satellite record.         
- 2020 Area is 444 k less than the 2010's average         
- 2020 Area is 1,398 k less than the 2000's average         
- 2020 Area is 99 k more than 2016         
- 2020 Area is 259 k less than 2019          
- 2020 Area is 290 k more than 2012         
___________________________________________         
NSIDC Total EXTENT as at 02-Sep-2020 (5 day trailing average) 4,166,113 KM2         
         
EXTENT loss on this day 76 k, 36 k more than the 2010's average loss of 40k         
         
- 2020 EXTENT is at position #2 in the satellite record.         
- 2020 EXTENT is 578 k less than the 2010's average         
- 2020 EXTENT is 1,622 k less than the 2000's average         
- 2020 EXTENT is 204 k less than 2016         
- 2020 EXTENT is 359 k less than 2019          
- 2020 EXTENT is 519 k more than 2012

___________________________________________
End-of-season wobbles continue - area up, extent down a lot.
NSIDC daily extent up by 47k after yesterday's drop of 196k.
Methinks the sensors and the algorithms are finding it difficult.            
___________________________________________         
Note: Click once on each image to see it full-size         
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

glennbuck

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Re: 2020 Sea ice area and extent data
« Reply #1444 on: September 03, 2020, 02:46:32 PM »
NSIDC Daily Area: September 2nd

Arctic Sea ice area: 2,762,901 million km^2.

Change from yesterday: Area gain of 26,340 km^2

(2020) NSIDC: Area daily: 2.762               NSIDC: Extent daily: 4.051


NSIDC: September daily area minimum     NSIDC: September daily extent minimum

(2012) 2.241                                             : 3.340  <<  Sep  16
(2016) 2.477                                             : 4.145         Sep   7               
(2011) 2.940                                             : 4.333         Sep   8
(2019) 2.960                                             : 4.166         Sep 17
(2017) 3.020                                             : 4.635         Sep 13
(2007) 3.050                                             : 4.155         Sep 18
(2008) 3.120                                             : 4.586         Sep 19
(2015) 3.160                                             : 4.387         Sep   8
(2018) 3.270                                             : 4.630         Sep 21
« Last Edit: September 03, 2020, 04:22:30 PM by glennbuck »

gerontocrat

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Re: 2020 Sea ice area and extent data
« Reply #1445 on: September 03, 2020, 03:08:48 PM »
NSIDC Graphs ....

Beaufort Sea - both area and extent still showing steep decline though very late in the day.

Central Arctic Sea
- area losses rebound, extent still in steep decline.
Concentration increases as the sea closes up (persistent winds from the Atlantic side)?
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

gerontocrat

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Re: 2020 Sea ice area and extent data
« Reply #1446 on: September 03, 2020, 03:37:25 PM »
NSIDC Summary Graphs - High Arctic  and the peripheral Seas

High Arctic
- Area in 3rd place, Extent in 2nd place. Difference largely due to increasing concentration of the Central Arctic Sea

Peripheral Seas - Area in 9th place, Extent in 14th place. Concentration extremely low at 40%. Mostly about the Greenland Sea. Might lose a lot of ice in the last week or two of the season.
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

mjb

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Re: 2020 Sea ice area and extent data
« Reply #1447 on: September 03, 2020, 03:51:43 PM »
I am new here, but not new to the matter...

What I always miss in those discussions around EXTEND is talking
about  the 'flaw' in the definition.

IF one solid square of ice breaks down into small pieces and spreads out 5 times
and melts half it's thickness. Then we get an increase in EXTEND by 5 times ...
While the volume is half and the little pieces soon gone completely ...

So my measure is VOLUME

Alphabet Hotel

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Re: 2020 Sea ice area and extent data
« Reply #1448 on: September 03, 2020, 04:07:50 PM »
NSIDC daily extent

Today's 1-day change was +47

7-day average:  (4051 − 4427) / 7  =  −54
14-day average: (4051 − 4816) / 14  =  −55

2020-08-19  4.816
2020-08-20  4.704  −112
2020-08-21  4.630    −74
2020-08-22  4.577    −53
2020-08-23  4.552    −25
2020-08-24  4.492    −60
2020-08-25  4.429    −63
2020-08-26  4.427      −2
2020-08-27  4.363    −64
2020-08-28  4.448    +85
2020-08-29  4.365    −83
2020-08-30  4.260  −105
2020-08-31  4.200    −60
2020-09-01  4.004  −196
2020-09-02  4.051    +47

gerontocrat

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Re: 2020 Sea ice area and extent data
« Reply #1449 on: September 03, 2020, 04:42:12 PM »
I am new here, but not new to the matter...

What I always miss in those discussions around EXTEND is talking
about  the 'flaw' in the definition.

IF one solid square of ice breaks down into small pieces and spreads out 5 times
and melts half it's thickness. Then we get an increase in EXTEND by 5 times ...
While the volume is half and the little pieces soon gone completely ...

So my measure is VOLUME
Which is updated and discussed bimonthly (twice a month) on the PIOMAS thread.

The relationship between area, extent & volume is discussed in all sorts of places, e.g. the "when will the Arctic go ioce-free" thread.

Have a wander around - use the search engine; you never know what you may find.
« Last Edit: September 03, 2020, 04:48:37 PM by gerontocrat »
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)