Arctic Sea Ice : Forum
Cryosphere => Arctic sea ice => Topic started by: Juan C. García on July 31, 2020, 04:18:39 AM

Until 2004, all years were above 10,000 km^{3}. The years 2005 and 2006 were on the 9,00010,000 km^{3} range. And from 2007 to 2019, the volume has been at 7,250 km^{3} or under. The worst year [2012] was 3,787 km^{3}.
Values from the PIOMAS Monthly Ice Volume Data:
http://psc.apl.uw.edu/research/projects/arcticseaicevolumeanomaly/data/ (http://psc.apl.uw.edu/research/projects/arcticseaicevolumeanomaly/data/)
Year Sept. Avg.
(10^{3} km^{3})
2000 11.08
2001 12.28
2002 10.85
2003 10.28
2004 10.04
2005 9.28
2006 9.11
2007 6.53
2008 7.25
2009 6.93
2010 4.74
2011 4.48
2012 3.79
2013 5.48
2014 6.97
2015 5.85
2016 4.53
2017 4.68
2018 5.08
2019 4.19
From lowest to highest:

in volume, I think that 2020 will end between 2012 and 2019, even that I expect that in the end of July, the year 2020 could be the lowest on record. Will it happen? We will know in 57 days.
For now, 3.754.25K km^{3} range.

Dropped another bin to 3.504.00. I expect a new record volume, this is just for safety's sake.

My guess assumes a quiet august. If we get a storm with pressure less than 965 and 2 meter or greater wave height, volume will approach a new low. An Atlantic hurricane generating a wave fetch of 400km would do great damage to the fractured and unsecured CAB.

I think 2020 can make it on top #3 position. Therefore I went for the 4.5 ± 0.25 k km³ bin as I did in July poll. I was a little surprised to find my vote in the very upper edge of votes submitted so far.

Too low to care about anymore?

I think it will be below 2019; 2019 has a small lead, but 'forgot' to keep on melting in september and high refreeze in september according to PIOMAS, which increased their average;
I can't see that happening this year, so much heat added into the arctic this year.
On the other hand, I don't know what to expect of the rest of the melting season. The numbers don't allign with my expectation, so I'm going for 3.75  4.25; Though I probably change to 1 or 2 bins lower if melting numbers allign with my expectation.

Just 2 more days to vote or change your vote. ;)

Bumped my vote up half a bin to 4.0  4 5

I already voted in June and haven't changed any of the bins since then...

I am staying in the range 3.754.25 K km3.
There is only one day left to vote or change your vote.

Dropping down half a bin as the high stayed high & the sun kept shining, & then the wind blew in the Beaufort.
August poll for PIOMAS: 3.504.00K km3 VHC (Very high confidence).
That's the bin that centres the 2012 record. This season has been exceptional as well so far so I think it's going to be down there with 2012.
All that sunlight on the ice in July will take its toll. That's direct energy for melting. In my amateur understanding, most will have been absorbed by the ice & some of the high frequency (violet) end will have gone straight through and heated up the water underneath.
Now we're getting to the time of year where there is heat in the water below the ice & how much is transferred to the ice will depend on how much the ice is stirred. So if the next month is windy over the ice then  in my amateur view  that would be big factor in pushing towards a record low minimum volume.

3.00 and 3.50 10^3 km^3

NSIDC Total Area as at 29Sep2020 (5 day trailing average) 3,056,442 KM2
Sea ice area gain on this day 27 k, 22 k less than the 2010's average gain of 49 k
 2020 area is at position #2 in the satellite record.
 2020 Area is 583 k less than the 2010's average
 2020 Area is 1,370 k less than the 2000's average
 2020 Area is 428 k less than 2016
 2020 Area is 494 k less than 2019
 2020 Area is 348 k more than 2012
NSIDC ASI area has been increasing very slowly. It is now 428K km^{2} against 2016, which was second lowest on record.
I wonder what it means in terms of PIOMAS volume. 2016 started to be the lowest volume on record in November (lower than 2012).
Regarding this poll, the question is if it will be above or under 4K km^{3} on September.

As the minimum appears to have been slightly above 4k (on the 15th), and very little chance that volume continued to drop after the 16th, I expect PIOMAS Sep average to be above 4k km3, and my poll entry to be proven wrong.

The figure of 4.333 thousand km3 must be an error.
My score is 42 in this case. Monthly average is 4.333. All daily values are below monthly average for some reason.
PIOMAS makes public several values:
 On their monthly comment, they release a rounded monthly value.
 They also publish a table with the monthly average, with an exact figure.
 They also publish a list of daily values.
 Finally, Wipneus has access to the daily values by region, that he makes public on ASIF.
For September 2020, PIOMAS published a rounded figure of 4,300 km^{3} and the exact value of 4,333 km^{3}. I agree with Gerontocrat that these values have a mistake. As Aluminium says, all daily values are below the official monthly average.
The average of daily values changes a little, depending on the way you handle the leap years. On these average and on the graph, I established that the day 244 corresponds to September 1^{st} and the day 273 corresponds to September 30^{th}, with no special handling for leap years. The average are the followings:
Year PIOMAS
Sept. Avg.
(1000 km^{3})
2011 4.485
2012 3.789
2016 4.533
2019 4.196
2020 4.162
So, 2020 is a little lower than 2019. Considering that PIOMAS is a model that cannot give you an exact figure, I will say that based on the PIOMAS daily values 2020 is even with 2019 and the correct average is 4.16 thousand km^{3}. I do not agree that 2020 is the third lowest, as it is said on the PIOMAS September comment.
So, from my point of view, the winner bins are 3.754.25 and 4.004.50 thousand km^{3}. There were 21 votes on those bins, of the total of 63 votes, which represent one third of the votes.
If we consider the 4,333 km3 value, the winner bins are 4.004.50 and 4.254.75 thousand km3. There were 9 votes on those bins, which represent 14.3% of the votes.

Has anyone asked them to explain the discrepancy between their detailed files and the published summary? There's always been some part of the volume calculation that Wipneus was unable to duplicate so I am not inclined to treat either value as reliable at the moment.

An email to the nice Dr. Zhang is needed (I have been too busy to write one).

An email to the nice Dr. Zhang is needed (I have been too busy to write one).
Dr Zhang has confirmed that the figure on the website is incorrect and our calculated value of 4162 Km^3 is correct. (the website has not yet been updated).
"I double checked. Your calculation is correct. We had an error at our end in calculating September mean.
Thanks for the note,
Jinlun"
The website has now been updated to 4200, PIOMAS apparently only reports the monthly figure to the nearest 100K.

Thanks a lot, DavidR.
Indeed, the nice Dr. Zhang.

Great news, DavidR! :)
In fact, they already made the correction on their page!
Thank you, Dr. Zhang and PIOMAS team!
http://psc.apl.uw.edu/research/projects/arcticseaicevolumeanomaly/ (http://psc.apl.uw.edu/research/projects/arcticseaicevolumeanomaly/)