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What will NSIDC 2021 Arctic SIE September average be?

Above 5.25 million km^2
0 (0%)
Between 4.75 and 5.25 million km^2
0 (0%)
Between 4.50 and 5.00 million km^2
2 (6.7%)
Between 4.25 and 4.75 million km^2
17 (56.7%)
Between 4.00 and 4.50 million km^2
5 (16.7%)
Between 3.75 and 4.25 million km^2
3 (10%)
Between 3.50 and 4.00 million km^2
1 (3.3%)
Between 3.25 and 3.75 million km^2
2 (6.7%)
Between 3.00 and 3.50 million km^2
0 (0%)
Between 2.75 and 3.25 million km^2
0 (0%)
Between 2.50 and 3.00 million km^2
0 (0%)
Between 2.25 and 2.75 million km^2
0 (0%)
Between 2.00 and 2.50 million km^2
0 (0%)
Under 2.00 million km^2
0 (0%)

Total Members Voted: 30

Voting closed: August 11, 2021, 01:18:13 AM

Author Topic: NSIDC 2021 Arctic SIE September average: August poll  (Read 1863 times)

Juan C. García

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NSIDC 2021 Arctic SIE September average: August poll
« on: August 01, 2021, 01:18:13 AM »
ATTENTION: There are two ASI extent polls on the ASIF. This one is for NSIDC sea ice extent monthly minimum or September average (which is also used for the SIPN sea ice outlook), the other is for JAXA sea ice extent daily minimum [provided by JAXA (ADS-NIPR-VISHOP)].

Make sure you are aware of the difference before voting.

These are the September averages on 2000-2020 (in million km2):

Year      Extent
2000        6.25
2001        6.73
2002        5.83
2003        6.12
2004        5.98
2005        5.50
2006        5.86
2007        4.27
2008        4.69
2009        5.26
2010        4.87
2011        4.56
2012        3.57
2013        5.21
2014        5.22
2015        4.62
2016        4.53
2017        4.82
2018        4.79
2019        4.36
2020 (*)   4.00

* Corrected by NSIDC. According to NSIDC October 2020 post, it was 3.92 million km2.
http://nsidc.org/arcticseaicenews/2020/10/
From lowest to highest:
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.

icefisher

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Re: NSIDC 2021 Arctic SIE September average: August poll
« Reply #1 on: August 01, 2021, 02:51:22 AM »
2015's average looks good to me right now.  4.62 it is.

Brigantine

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Re: NSIDC 2021 Arctic SIE September average: August poll
« Reply #2 on: August 01, 2021, 05:29:59 AM »
links to poll threads:
Month - PIOMAS / NSIDC / JAXA
June ___ link ____ link ____ link
July ____ link ____ link ____ link
August _ link ____ N/A ____ link

Brigantine

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Re: NSIDC 2021 Arctic SIE September average: August poll
« Reply #3 on: August 01, 2021, 05:58:08 AM »
I take my June prediction as an anchor, slide up 1 bin, and squash the spread into half the width.

4.25 - 4.75

Assumed bin chances: (>5.25) 0%; 2%; 10%; 34%; 35%; 14%; 3%; 2%; 0%; 0%; 0%; 0%; 0% (<2.50)

Stephan

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Re: NSIDC 2021 Arctic SIE September average: August poll
« Reply #4 on: August 03, 2021, 09:31:21 PM »
Unlike the years before I changed my bet one bin higher to 4-4.5 M km².
It is too late just to be concerned about Climate Change

The Walrus

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Re: NSIDC 2021 Arctic SIE September average: August poll
« Reply #5 on: August 03, 2021, 09:43:02 PM »
Both 2011 and 2015 look like the best fits.  Somewhere around 4.6.

Juan C. García

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Re: NSIDC 2021 Arctic SIE September average: August poll
« Reply #6 on: August 10, 2021, 05:52:28 AM »
Moving to the range 4.25 - 4.75 km2.

19 hours to vote or change your vote...   ;)
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.

Brigantine

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Re: NSIDC 2021 Arctic SIE September average: August poll
« Reply #7 on: August 10, 2021, 09:22:02 AM »
I take my June prediction as an anchor, slide up 1 bin, and squash the spread into half the width.

4.25 - 4.75

Assumed bin chances: (>5.25) 0%; 2%; 10%; 34%; 35%; 14%; 3%; 2%; 0%; 0%; 0%; 0%; 0% (<2.50)
I'll go out on a limb and change my vote to 80%*[4.65 +/- 0.25Z]+20%*[4.25 +/- 0.5Z]

4.50 - 5.00

Assumed bin chances: (>5.25) 1%; 7%; 23%; 34%; 21%; 8%; 3%; 2%; 1%; 0%; 0%; 0%; 0% (<2.50)
« Last Edit: August 10, 2021, 10:00:05 AM by Brigantine »

gerontocrat

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Re: NSIDC 2021 Arctic SIE September average: August poll
« Reply #8 on: August 10, 2021, 07:53:37 PM »
With just 35-40 days to minimum (probably) the chances of a major uptick or major slowdown in sea ice extent loss diminish every day.

The September monthly average for NSIDC sea ice extent, assuming remaining eea ice extent loss to be at the average of the last 10 years, comes in at 4.64 million km2, some 306k km2 above the long-term linear trend, and 644k km2 above 2020. (see attched)

A "percentages golfer" would therefore go for a range of 4.5 to 5 million km2. But I cling to the faint belief that there is a bit of life left in the season (with no real evidence), so am going for one bin lower at 4.25 to 4.75 million km2.

Perhaps this year there is enough global heating to burn down large parts of the Northern Hemisphere but not enough left over to boil the Arctic Ocean.

click image to enlarge
« Last Edit: August 11, 2021, 12:39:41 AM by gerontocrat »
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The Walrus

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Re: NSIDC 2021 Arctic SIE September average: August poll
« Reply #9 on: August 10, 2021, 08:16:05 PM »
I agree with you gerontocrat.  I hedged my bet by going with the lower bin, fully realizing that if the final number comes in at 4.64, either bin is satisfied.  It seemed more likely that it would be lower than higher, but that just might be my own biases.

oren

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Re: NSIDC 2021 Arctic SIE September average: August poll
« Reply #10 on: August 11, 2021, 12:11:56 AM »
Upping by one bin to 4.25-4.75, I can't see 2020 (or 2012) performance being repeated.

Brigantine

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Re: NSIDC 2021 Arctic SIE September average: August poll
« Reply #11 on: August 11, 2021, 09:19:31 AM »
A summary of June-July-August votes:

June - 39 votes total
  • 4.21 Upper Quartile (interpolated within bin) - 0.30 above JAXA
  • 3.96 Median - 0.28 above JAXA
  • 3.69 Lower Quartile - 0.35 above JAXA
  • 19 or 49% voters at most can win (sum of 2 adjacent bins)
  • 6 poll options required to include 90% of votes
  • 0.52 Inter-quartile range


July - 36 votes total
  • 4.21 (+/- 0) Upper Quartile - 0.22 above JAXA
  • 4.02 (+0.06) Median - 0.24 above JAXA
  • 3.77 (+0.08) Lower Quartile - 0.24 above JAXA
  • 23 (+4) or 64% (+15) voters at most can win (sum of 2 adjacent bins)
  • 5 (-1) poll options required to include 90% of votes
  • 0.44 (-0.08) Inter-quartile range


August - 30 votes total
  • 4.54 (+0.33) Upper Quartile - 0.24 above JAXA
  • 4.43 (+0.47) Median - 0.24 above JAXA
  • 4.21 (+0.52) Lower Quartile - 0.21 above JAXA
  • 22 (+3) or 73% (+24) voters at most can win (sum of 2 adjacent bins)
  • 4 (-2) poll options required to include 90% of votes
  • 0.33 (-0.19) Inter-quartile range

oren

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Re: NSIDC 2021 Arctic SIE September average: August poll
« Reply #12 on: August 12, 2021, 11:27:50 AM »
Big thanks for the analysis and for posting the links to previous polls.

Killian

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Re: NSIDC 2021 Arctic SIE September average: August poll
« Reply #13 on: August 12, 2021, 11:39:40 AM »
Pretty big change from my first and second: 4.25 ~ 4.75. Will not at all be surprised to see 5.0. Best match continues to be 2011 to a near-perfect match, but I think this year will bottom out higher.

Tealight

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Re: NSIDC 2021 Arctic SIE September average: August poll
« Reply #14 on: August 16, 2021, 02:34:33 PM »
According to my SIPN forecast from 13th August the 4.75 to 5.25 bin would have been the safest option. 4.5 - 5.0 is also a good option.

Richard Rathbone

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Re: NSIDC 2021 Arctic SIE September average: August poll
« Reply #15 on: August 28, 2021, 11:48:03 AM »
https://www.arcus.org/sipn/sea-ice-outlook/2021/august

SIPN report now out. The median was 4.39. Tealights was the second highest.

University of Washington (PIOMAS in prediction mode) is in the pack this time (4.32).

Freegrass

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Re: NSIDC 2021 Arctic SIE September average: August poll
« Reply #16 on: August 28, 2021, 12:07:15 PM »
According to my SIPN forecast from 13th August the 4.75 to 5.25 bin would have been the safest option. 4.5 - 5.0 is also a good option.
I'm one of the two who picked the between 4.5 - 5.0 option. So it's looking good for me...
When factual science is in conflict with our beliefs or traditions, we cuddle up in our own delusional fantasy where everything starts making sense again...

The Walrus

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Re: NSIDC 2021 Arctic SIE September average: August poll
« Reply #17 on: August 28, 2021, 01:45:26 PM »
According to my SIPN forecast from 13th August the 4.75 to 5.25 bin would have been the safest option. 4.5 - 5.0 is also a good option.
I'm one of the two who picked the between 4.5 - 5.0 option. So it's looking good for me...

Yes.  I was not as optimistic as you, as I went one bin lower.  Still, it is entirely possible that your bin may not be good enough, if the slow melt continues.

Freegrass

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Re: NSIDC 2021 Arctic SIE September average: August poll
« Reply #18 on: September 16, 2021, 10:08:00 PM »
According to my SIPN forecast from 13th August the 4.75 to 5.25 bin would have been the safest option. 4.5 - 5.0 is also a good option.
I'm one of the two who picked the between 4.5 - 5.0 option. So it's looking good for me...

Yes.  I was not as optimistic as you, as I went one bin lower.  Still, it is entirely possible that your bin may not be good enough, if the slow melt continues.
It looks like you were still good with your pick. As was I. I was thinking somewhere around 4.75, and it looks like we're a little below that. So it's all good.
When factual science is in conflict with our beliefs or traditions, we cuddle up in our own delusional fantasy where everything starts making sense again...

Juan C. García

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Re: NSIDC 2021 Arctic SIE September average: August poll
« Reply #19 on: September 16, 2021, 10:30:39 PM »
Sep 1-15 average is 4.87M km2.
Sep 15th daily value is 4.741M km2.
I voted to 4.25-4.75M km2, so I am below too.
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.

The Walrus

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Re: NSIDC 2021 Arctic SIE September average: August poll
« Reply #20 on: September 16, 2021, 10:40:19 PM »
Sep 1-15 average is 4.87M km2.
Sep 15th daily value is 4.741M km2.
I voted to 4.25-4.75M km2, so I am below too.

Yes, not sure the Sept. average will dip below 4.75.  I suspect the extent will start rising very soon.

gerontocrat

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Re: NSIDC 2021 Arctic SIE September average: August poll
« Reply #21 on: September 16, 2021, 11:01:28 PM »
Not that I want to rain on anyone's parade (liar, liar, pants on fire) but... a cautionary note.

IFF sea ice extent gains for the remainder of September are at the previous 10 years' average then the September average of NSIDC 5-day sea ice extent will be 4.915 million km2, 12th lowest in the satellite record, 0.92 million km2 above Sept 2020 and 0.55 million km2 above the long-term linear trend.

It is therefore in the realms of possibility that if a cool / cold pattern strengthens, remaining sea ice extent gains this month could produce a September average that just about breaches the 5 million km2 mark.
___________________________________________
Note:- Although this is the 5 day average, the difference in the one-day average will be very very small.
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Freegrass

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Re: NSIDC 2021 Arctic SIE September average: August poll
« Reply #22 on: September 16, 2021, 11:14:45 PM »
OK... Time for a stupid question... What's the September average? I thought this was about the minimum. What's the difference with the average?

Edit: I had some time to think about it, and I guess the average means adding all days of september together, and than taking an average?

So my new question is; Why is that important? What do we learn from that?
« Last Edit: September 16, 2021, 11:39:42 PM by Freegrass »
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gerontocrat

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Re: NSIDC 2021 Arctic SIE September average: August poll
« Reply #23 on: September 17, 2021, 12:10:28 AM »
At and close to the minimum, there is usually a lot of very low sea ice concentration ice. So a few days of sea ice drift can either greatly compact the ice or greatly spread out ice with a large impact on sea ice extent

So a very low or surprisingly high one day minimum may just be a function of sea ice drift - a flash in the pan. The September average smooths out and tends to remove these short-term changes and is therefore more significant.

Using just one day's measurement out of 365 to make statements about trends in the Arctic sea ice is, to say the least, problematical. (or maybe a bit like Senator James Inhofe who in February 2015 threw a snowball to the Chair of the Senate - It's snowing in Washington D.C. - Global Warming? Hogwash!!)



https://time.com/3725994/inhofe-snowball-climate/
« Last Edit: September 17, 2021, 09:18:16 AM by gerontocrat »
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Juan C. García

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Re: NSIDC 2021 Arctic SIE September average: August poll
« Reply #24 on: September 17, 2021, 01:41:52 AM »
Yes, not sure the Sept. average will dip below 4.75.  I suspect the extent will start rising very soon.
The extent is already rising. As Gero wrote, we can expect an average around 4.9M km2.

So my new question is; Why is that important? What do we learn from that?
I like to follow both, the daily minimum and the monthly average. Sometimes the year was very bad for the ice and we can see it on the daily minimum, but the year had a fast september refreeze, so we don't see it on the average.

Also, the worst years (especially 2012 and 2020), the ocean stayed hot warm, so we have a late refreeze, that can go until mid-october. The september average is very low then.

And it is important to follow the area and volume also.

P.S. I think that 2007 late refreeze made the 2007 September average difficult to match by other years, fact that has been used by deniers to affirm that 2012 was an outlier and other years were not as bad as 2007. That is not true, if you follow the ADI-JAXA daily minimum and especially, if you follow the volume. 2007 is 3rd lowest on NSIDC monthly average now (it was second until 2019), but 5th lowest on ADI-JAXA daily minimum and 11th lowest on PIOMAS volume monthly average.
« Last Edit: September 17, 2021, 06:09:59 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.

Freegrass

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Re: NSIDC 2021 Arctic SIE September average: August poll
« Reply #25 on: September 17, 2021, 08:27:01 AM »
Ok, I understand now. Thanks for the explanation all! I guess the moral of the story is that extent is such an arbitrary number. The more important numbers are area and volume. Especially volume. But that's also the most difficult number to figure out due to the fact that it's not as easy to figure out ice thickness compared to the 2D numbers of area and and extent...

Too bad HYCOM wasn't really good with extent and area this year... I assume thickness is what they're better at - due to the fact that submarines depend on it to surface? What if we use NSIDC extent and area, combined with HYCOM thickness? What would that give us?
When factual science is in conflict with our beliefs or traditions, we cuddle up in our own delusional fantasy where everything starts making sense again...

KenB

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Re: NSIDC 2021 Arctic SIE September average: August poll
« Reply #26 on: September 17, 2021, 03:28:14 PM »
Ok, I understand now. Thanks for the explanation all! I guess the moral of the story is that extent is such an arbitrary number. The more important numbers are area and volume. Especially volume. But that's also the most difficult number to figure out due to the fact that it's not as easy to figure out ice thickness compared to the 2D numbers of area and and extent...

Too bad HYCOM wasn't really good with extent and area this year... I assume thickness is what they're better at - due to the fact that submarines depend on it to surface? What if we use NSIDC extent and area, combined with HYCOM thickness? What would that give us?

For a look at NSIDC Extents in September, see https://forum.arctic-sea-ice.net/index.php/topic,3183.msg275410.html#msg275410 where they're plotted in a couple different ways.  Generally speaking, September tends to be pretty flat relative to the rest of the year's changes, it seems. 

WRT combining various measurements, certainly building 'ensemble' models is a very well-studied technique in machine learning, but in almost all those cases, there's some subset of the inputs for which the correct answer is known, which isn't really our situation, unfortunately.  Also, I'm strongly reminded of Juan's signature: 

"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."
"When the melt ponds drain apparent compaction goes up because the satellite sees ice, not water in ponds." - FOoW