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What will the NSIDC 2013 Arctic SIE September minimum be?

More than 5.0 million km2
0 (0%)
Between 4.75 and 5.0 million km2
0 (0%)
Between 4.5 and 4.75 million km2
1 (1.9%)
Between 4.25 and 4.5 million km2
2 (3.8%)
Between 4.0 and 4.25 million km2
0 (0%)
Between 3.75 and 4.0 million km2
6 (11.3%)
Between 3.5 and 3.75 million km2
5 (9.4%)
Between 3.25 and 3.5 million km2
4 (7.5%)
Between 3.0 and 3.25 million km2
10 (18.9%)
Between 2.75 and 3.0 million km2
6 (11.3%)
Between 2.5 and 2.75 million km2
5 (9.4%)
Between 2.25 and 2.5 million km2
3 (5.7%)
Between 2.0 and 2.25 million km2
3 (5.7%)
Between 1.75 and 2.0 million km2
1 (1.9%)
Between 1.5 and 1.75 million km2
1 (1.9%)
Between 1.25 and 1.5 million km2
0 (0%)
Between 1.0 and 1.25 million km2
0 (0%)
Between 0.75 and 1.0 million km2
1 (1.9%)
Between 0.5 and 0.75 million km2
1 (1.9%)
Between 0.25 and 0.5 million km2
3 (5.7%)
Between 0 and 0.25 million km2
1 (1.9%)

Total Members Voted: 51

Voting closed: May 31, 2013, 12:35:36 PM

Author Topic: NSIDC 2013 Arctic SIE September minimum: May poll  (Read 11712 times)

Neven

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NSIDC 2013 Arctic SIE September minimum: May poll
« on: May 07, 2013, 12:35:36 PM »
Okay, I've decided to do another poll besides the CT SIA daily minimum poll. Mind the differences between these two polls: one is for area and the lowest daily value, the other for extent and the monthly (September) average.

Here's my standard poll text:

It should be 'fun' and interesting to hold a poll each month, to see how opinions change according to sea ice rhythm and pace. These monthly polls can then also function as a dedicated thread for everything concerning NSIDC sea ice extent. Daily updated data can be found here.

Again, this poll is for NSIDC sea ice extent monthly minimum (unlike the other popular measure: Cryosphere Today sea ice area daily minimum), so we're looking for the average Arctic sea ice extent number for September 2013.

Here's how things are currently looking based on data up to May 7th:



Not very clear this one. Sorry about that. There are more graphs of course on the ASIG.

These are the September minimums for the last 7 years (in millions km2, found here):

    2005: 5.57
    2006: 5.92
    2007: 4.30
    2008: 4.73
    2009: 5.39
    2010: 4.93
    2011: 4.63
    2012: 3.61

Before finalizing the poll, I'd like to ask you guys first how many options I should include, what range, what interval, etc.
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OldLeatherneck

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Re: NSIDC 2013 Arctic SIE September minimum: May poll
« Reply #1 on: May 07, 2013, 12:51:18 PM »
Neven,

1.5 to 4.5  in 0.25 increments.

This range allows for an unanticipated increase slightly more than the 2008-2009  increase of 0.66 as well as a significant decrease in excess of the 2006-2007 decrease of 1.62.  No matter what we are feeling, we must let history provide some boundaries to our conjectures.
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crandles

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Re: NSIDC 2013 Arctic SIE September minimum: May poll
« Reply #2 on: May 07, 2013, 03:00:35 PM »
1.5 to 4.5  in 0.25 increments.

0.0-0.6
0.6-1.1
1.1-1.5
1.5-1.75
continue 0.25 increments to 4.5
4.5-4.9
4.9-5.4
5.4+

is 18 options. Seems pretty sensible to me.

Quote
No matter what we are feeling, we must let history provide some boundaries to our conjectures.

I agree that that is sensible, but if some people want to go out on a limb, should we give them the opportunity and risk (=opportunity to be ridiculed?) or simple censor them?

Perhaps poll question should make clear it is asking for sensible conjectures and not extreme feelings of foreboding or feelings that the risk is overdone?

Richard Rathbone

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Re: NSIDC 2013 Arctic SIE September minimum: May poll
« Reply #3 on: May 07, 2013, 07:01:32 PM »
Keep it simple. 0-6 in 0.5 sized bins and one bin for greater than 5.

Neven

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Re: NSIDC 2013 Arctic SIE September minimum: May poll
« Reply #4 on: May 07, 2013, 09:06:32 PM »
Crandles, isn't it better - or more esthetically appealing  ;) - to keep bins the same size?

I agree that we have to narrow it down as the melting season progresses.

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Neven

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Re: NSIDC 2013 Arctic SIE September minimum: May poll
« Reply #5 on: May 07, 2013, 10:04:14 PM »
Larry Hamilton is trying to set up a crowd-sourced prediction of minimum Arctic sea ice over on the ASIB, just in case someone missed it.
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slow wing

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Re: NSIDC 2013 Arctic SIE September minimum: May poll
« Reply #6 on: May 07, 2013, 10:35:38 PM »
Neven,

  Thanks for setting up these polls, which are very interesting.

I agree with you on the advantages of using even intervals, and further with OLN and your other poll in using intervals of 0.25 Mkm^2. I would suggest that, like the area poll, it should go down to zero and should also have a 'greater than' bin. For example, it could be 0 to 5 Mkm^2 in 0.25 intervals, plus an additional bin for >5. That is 21 bins.

Cheers, SW.
« Last Edit: May 07, 2013, 11:37:54 PM by slow wing »

crandles

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Re: NSIDC 2013 Arctic SIE September minimum: May poll
« Reply #7 on: May 07, 2013, 11:36:27 PM »
Crandles, isn't it better - or more esthetically appealing  ;) - to keep bins the same size?

I agree that we have to narrow it down as the melting season progresses.

Yes perhaps it is better at least for the first poll.

icebgone

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Re: NSIDC 2013 Arctic SIE September minimum: May poll
« Reply #8 on: May 08, 2013, 04:52:02 AM »
Either Crandle's or Slow Wing's bucket sizes will work.  I think most of us think of a range of estimates as satisfying our decision making processes rather than a point estimate.  Over on the ASIB many used ranges, including myself.  Perhaps as we get closer to minimum, ranges can be pruned and standard deviations tightened to make tracking easier.

Neven

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Re: NSIDC 2013 Arctic SIE September minimum: May poll
« Reply #9 on: May 08, 2013, 03:17:05 PM »
I went with Slow Wing's set-up, although 21 is a lot of bins, but what can you do? Poll is open as of now.

I went for between 3.25 and 3.5 million km2, a tad lower than I would've liked, but I've noticed in the past couple of melting seasons that I'm too conservative.
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Laurent

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Re: NSIDC 2013 Arctic SIE September minimum: May poll
« Reply #10 on: May 08, 2013, 04:54:06 PM »
I choosed 2.25 to 2.5 million km2.
The logic ? If I look at the trend in volume, total melting is scheduled for 2014 or 2015, let say 2014 (with exponential trend as I see it). So the surface has to be half way between the average of the last 2 years, so I choose slightly above !
The potential error is high, depend of the weather !!!
North pole ice free this year !

Jim Williams

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Re: NSIDC 2013 Arctic SIE September minimum: May poll
« Reply #11 on: May 08, 2013, 11:59:26 PM »
Given that we could have complete melt-out and still have half a million as the average Sept extent I've decided to pass.  While I still think it plausible that there'll be complete melt-out, I don't know that it will be much before the end of Sept.

sofouuk

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Re: NSIDC 2013 Arctic SIE September minimum: May poll
« Reply #12 on: May 09, 2013, 03:43:20 AM »
posted an aggressive bid of 3.0 M km^2 to L. Hamilton - a bit pessimistic, so 3.0-3.25 here. it won't be a good year for the ice, but the disaster will be postponed a few years yet

Vergent

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Re: NSIDC 2013 Arctic SIE September minimum: May poll
« Reply #13 on: May 10, 2013, 04:04:21 AM »
.25-.5

While I only give it a 20% chance, the precautionary principle says that you prepare for the worst reasonable eventuality. My reasoning proceeds from volume to area, and then to extent.

VOLUME

PIOMAS has been losing an average of 800km^3/ year, for September volume, for the last 10 years. It has been accelerating.



Thanks to Jim Pettit for this graph.

It can be seen that the rate of volume loss has changed dramatically in recent years. The slope of 2013 looks steeper than 2012. If you look at mid june, in a month and a half, 2012 lost 1k km^3 more than 2011, which lost 1k more than 2010, which lost 2k more than the climatology.



Again, thanks Jim.

This creates an early significant area anomaly i.e. Albedo feedback. All that extra energy keeps the area loss steep even after the insolation starts falling in mid August. This year I expect these trends to continue in spades. Solar irradiance is increasing, ENSO is rising and, there is so much more thin first year ice than there has ever been before.

I am expecting GAC12 will no longer be considered great come September.

Vergent
« Last Edit: May 13, 2013, 03:31:25 AM by Vergent »

Pmt111500

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Re: NSIDC 2013 Arctic SIE September minimum: May poll
« Reply #14 on: May 10, 2013, 06:25:54 AM »
Here's the current distribution of ASIB-crowd source estimate Sea ice extent votes smoothed somehow, project 'back to the statistics' (via libreoffice) continues (while eliminating lowest throughs pretty well, the chosen weighted-average method seems to accentuate highest peaks somewhat)

(modified a bit later): I've used a wrong constant divisor for this weighted-average, I really should consult the books on statistics before doing this sort of charts.  The general shape is correct, though. Sorry. Possibly Larry Hamilton will produce the proper curve after the poll is over if this is going to be the ASIB contribution in the SEARCH Sea Ice Outlook.

(modified yet later): this method places far too much spread on the error limit. +/- 0,8 at 80% confidence it looks like. While the average error estimate of the ASIB (at 95%?) is now at +/- 0,64. Maybe Tamino could do this in a moment but not me. :-|

(modified 11.05.2013)
For the record, I used slots of 0,2 and 5 slot weighted averages, but alas, the weighting multipliers for the 2 other slots both sides the calculated one should be taken from the normal distribution tables (for the wanted error limit) for these and not guessed (like I did). Likely 0,1 slots are still better for accuracy, but the overall look will become bumpier. If one used some general error limit (calculated from the whole set) too, the individual peaks would likely vanish and the whole set would be skewed to the low side.
« Last Edit: May 11, 2013, 08:10:57 AM by Pmt111500 »

frankendoodle

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Re: NSIDC 2013 Arctic SIE September minimum: May poll
« Reply #15 on: May 13, 2013, 02:53:25 AM »
I put down 3.75 to 4.0 mkm2 just for continuity sake with my Crowd Source Prediction on Neven's blog, which I derived thusly:

3.85 million km2 +- 0.885
I took the September NSIDC SIE averages from 2000-2012 and plotted a linear trend line. Using monthly averages gave me a smaller SD then just listing the minimums.Then I derived the average deviation of the means from the minimums and subtracted it from the projected 2013 monthly mean.

But just looking at some of the large pools of open water in the Kara and Laptev Seas; and the ones around Franz Josef Land, Sevemaya Zemlya and the New Siberian Islands (all above 80N) I know I'm being way too conservative. I'm sure my June Poll vote will be different. 

wili

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Re: NSIDC 2013 Arctic SIE September minimum: May poll
« Reply #16 on: May 14, 2013, 12:50:54 PM »
Pmt, thanks for the graphic, even with your caveats.

That looks like a pretty reasonable probability spread--a wide range of possibilities, but with a fattish tail on the low end and a sharp drop off on the high end. My own inclinations would be to make the low tail a bit fatter yet, but maybe that is what you are saying a proper statistical approach would do?
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Re: NSIDC 2013 Arctic SIE September minimum: May poll
« Reply #17 on: May 14, 2013, 01:57:41 PM »
Hi Wili, I tried to do that properly with 90 votes in, and the caveats apply... now (with 104 values?) there's been a couple of higher estimates and plenty more more in the middle range so that would make it lean much less to the low side and a slightly higher in the middle. Properly done, this would mean the 2-sigma range (error bars) has got slightly larger.

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Pmt111500

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Re: NSIDC 2013 Arctic SIE September minimum: May poll
« Reply #19 on: May 15, 2013, 07:19:44 AM »
yes, Vergent, I know that, I should relearn what I knew about stats about 18 years ago and learn some more of it and physics to be a proper scientist. Then learn to use the appropriate software and some programming. But, this is the net and not a peer-reviewed journal (though peer-review happens on some form here too (f.e. volume predictions thread)) so I'll continue to post slightly skewed analysis about ice, why should the denialati have the priviledge? I try to keep those simple, so a high-schooler with sufficient interest can repeat those.

crandles

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Re: NSIDC 2013 Arctic SIE September minimum: May poll
« Reply #20 on: June 01, 2013, 12:15:32 AM »
Oops missed the deadline.

Using minimum volume prediction of 2.62 as per volume prediction thread reply #152 by Chris Reynolds then I convert that to September average extent of 3.24 M Km^2 with average thickness of 0.81m.

So only just sneaking into the 3 to 3.25 M Km^2 category.


crandles

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Re: NSIDC 2013 Arctic SIE September minimum: May poll
« Reply #21 on: June 04, 2013, 12:35:55 PM »
NSIDC monthly extent and area are out:

Quote
1990  5      Goddard      N  13.30  10.84
1991  5      Goddard      N  13.51  11.44
1992  5      Goddard      N  13.25  11.37
1993  5      Goddard      N  13.54  11.35
1994  5      Goddard      N  13.73  11.60
1995  5      Goddard      N  13.04  10.76
1996  5      Goddard      N  13.06  11.22
1997  5      Goddard      N  13.32  11.17
1998  5      Goddard      N  13.80  11.35
1999  5      Goddard      N  13.86  11.61
2000  5      Goddard      N  13.18  11.18
2001  5      Goddard      N  13.72  11.32
2002  5      Goddard      N  13.12  11.11
2003  5      Goddard      N  13.00  10.82
2004  5      Goddard      N  12.58  10.86
2005  5      Goddard      N  12.99  10.83
2006  5      Goddard      N  12.62  10.39
2007  5      Goddard      N  12.89  10.71
2008  5      Goddard      N  13.19  10.92
2009  5      Goddard      N  13.40  11.15
2010  5      Goddard      N  13.11  10.54
2011  5      Goddard      N  12.81  10.41
2012  5      NRTSI-G      N  13.13  10.65
2013  5      NRTSI-G      N  13.10  10.87

7th lowest extent.
11th lowest area.

Area higher than 1990!

(warning incoming shouts of recovery expected)