SIE update 31: when all is over and done

I'm regularly writing updates on the current sea ice extent (SIE) as reported by IJIS (a joint effort of the International Arctic Research Center and the Japan Aerospace Exploration Agency) and compare it to the sea ice extents in the period 2005-2009. The IJIS graph is favoured by almost everyone, probably because it looks so nice compared to other graphs (like the one by Arctic ROOS, the University of Bremen and the Danish Meteorological Institute). All the years have a nice colour of their own which makes it easy to eyeball the differences between trends. Most of the betting on minimum SIE is based on the IJIS data. NSIDC has a good explanation of what sea ice extent is in their FAQ.

September 19th 2010

I think the melting season is over, in the sense that minimum extent has been reached once and for all:

I could be wrong of course (there's a caveat for ya) and if I am I'll be in good company. It is definitely possible that the arm in the East Siberian Sea gets amputated some more or some of that spread out ice on the other side of the ice pack gets pushed back and compacted. In that case minimum extent might dip down a little further. But maybe not. Like I've said many times before: when you see a PIPS ice displacement map such as the one below at this (far out) point in the season...

 

...you know that the end of extent declines has been signalled. Small arrows are deadly at this point. The freeze-up will seize this chance and trump warm SSTs and compacting winds, especially since the weather forecast is projecting high-pressure areas: exit. More of that at the end of this update.

The current difference between 2010 and the other years is as follows:

• 2005: -572K
• 2006: -1060K
• 2007: +532
• 2008: +95K
• 2009: -535K 

A virtual tie with 2008, I'd say, as far as extent is concerned.

Artful Dodger sent me some more statistics for this month. It shows the average daily and total extent decrease for September until minimum extent compared to other IJIS years. 'Sep Dec' is the September cumulative decrease in SIE, computed as follows (SIE on date of minimum SIE) - ( Aug 31 SIE ):

Year   Sep Avg    Sep Dec    2010    Diff%
2010    -28,658    515,781    515,781    0.00%
2007    -14,688    352,500    515,781    46.32%
2005    -15,263    335,782    515,781    53.61%
2008    -35,781    322,031    515,781    60.17%
2003    -13,898    250,157    515,781    106.18%
2009    -15,180    197,344    515,781    161.36%
2006    -13,784    192,969    515,781    167.29%
2002    -20,885    187,969    515,781    174.40%
2004    -12,131    133,437    515,781    286.54%

Here's the IJIS sea ice extent graph:

Cryosphere Today sea ice area has been going up quite steeply in the past few days, even compared to the 1979-2008 mean. This must be due to all the holes in the central ice pack freezing up and of course freezing at the edges as well. The anomaly has therefore gone up as well and currently stands at -1.509 million square km:

 

The combination of extent decreases and area increases has the 2010 trend line of our CAPIE (Cryosphere area per IJIS extent) graph going through the roof. It went from 62.6% in the last SIE update to 68.8%:

When all is over and done, there is nothing left for me but to show the ECMWF weather forecast for the coming days:

 

In 2-3 days from now a high will try to reform over the Beaufort Sea, but I think that will be too late for a return of the conditions that brought us the second extent minimum. So long, sea water. Welcome back, sea ice.

TIPS - Other interesting blog posts and news articles concerning the Arctic and its ice:

Patrick Lockerby keep us up-to-date with regards to the Petermann/Lockerby Ice Island: Petermann's Progress.

From January 23-28 there will be another Arctic Frontiers conference in Tromsø, Norway, with the title “Arctic Tipping Points” (how appropriately timed). Here you can read some of the abstracts of presentations of keynote speakers.

Gareth Renowden from the Hot Topic blog talks some more about the double dip we experienced in the past week.

The Norwegians (and Russians) have practically made it through the Northwest Passage!

Comments

[Artful Dodger]

Neven, thanks for the wind forecast animation. 'Ask and you shall receive'. You do a marvelous service for people interested in the future of the Arctic, and in turn, the future of us all.

Wow! Our CAPIE ratio shows that the Summer melt season was extended by 3 full weeks in 2010. I can't wait for the Fall Ice Advection Season ;^)

Outstanding blog! Thank-you, and Blessings on your Home.

[Neven]

Thanks, Lodger!

And now I'm actually hoping that IJIS will report an increase in extent later tonight, just so I don't end this year's melting season with a major gaffe. :-p

Ah well, I'll just blame PIPS.

[Artful Dodger]

I've been looking at the intra-day ice concentration maps from Uni-Hamburg. There's some definite spreading at the tip of the 'Beaufort finger' but with Healy there reporting both air and sea temps, and knowing the salinity, we can definitely say that this is melt.

There also seems to be an erosion of the ice near Svalbard at the entrance to Fram Strait. Both these area record the highest values on the SST anomaly maps, so it's expected.

There's another uptick on the DMI.dk 80N temp graph, so that's probably heat release from freezing. Overall the balance is sliding relentlessly to Winter, but I'd like to see one more good wind event to round out September, and take us to some more new records!

[Peter Ellis]

I think the melting season is over, in the sense that minimum extent has been reached once and for all.

Right, well I'm going to stick my neck out and predict that you're wrong. This is based largely on arrogance and ignorance, but hey, it's fun :-)

Looking at the IJIS figures to date, the slowdown of melt at the end of the summer follows a roughly quadratic curve. That is, there is a linear decline in the daily melt figures in the days leading up to the minimum. Fitting a linear trend to the daily loss figures from 1st August through to 18th September, the melt amount is declining by ~1k per day on average. This is much less than previous years: i.e. the fat lady is simply refusing to sing. And with a lot of ice still at lower latitudes, why should she?

This figure of ~1k per day change in daily melt is quite stable to the choice of period used for the regression, in fact it's at the conservative end of the range (i.e. earliest prediction of melt date). With a current melt of ~20k (the regression actually gives 18k), that predicts that the melt season has at least two and a half weeks left to run, and that the total left to melt before the true minimum is around 170k.

Thus, I shall predict that the melt season will not end until after the start of October, and that the final figure will be below 4.6 million sq km. There may be more "false minima" between now and then, because there's a lot of noise around the trendline. Interestingly, R Gates over at WUWT is predicting the melt season to go on until October and bottom out at 4.5 million, so it's not just me.

That's my prediction: let the chips fall where they may :-)

[Neven]

This is based largely on arrogance and ignorance,

Looks like we're on for a clash of the Titans! :-p

[Steve Bloom]

WUWT? With backing like that..

As Dodger says, the big upcoming question is advection. Will any of the multi-year ice survive?

[Artful Dodger]

Peter: I performed a similar analysis on Aug 21, and sent some of the results to Neven. One of the regressions I performed was on the 30-day moving average for 2007 daily change in SIE:

In this Chart, Day 1 is Aug 22, 2007. As your analysis also indicated, there is a consistent linear decline in the daily rate of change in SIE (in the 2007 example above, it's about 1,700 km^2 / day).

The regression line crosses the X-axis on Day 28, which is Sep 18, 2007. This can be interpreted as the day 'melt' equals zero, or just 'the end of the melt season for 2007'.

Even so, Sep 2010 has shown us that it won't be easily tamed, outperforming 2007 by 46%. This is entirely reasonably because the Sea Ice is about half the thickness of 2007 (anyone care to do a PIOMAS estimate?)

So far in 2010 the winds and SSTs have provided the heat. But unless we have another sustained wind event to provide mechanical mixing, the melt will grind to a halt and things will freeze in place. Either could happen, it's somewhat random. Ask me on Oct 4 ;^)

Right now, I think it is more useful to talk about Compaction potential, which will be the subject of one of my next comments...

Cheers, mate!

[logicman]

Neven: while I have been unwell I have popped in here at least once a day to keep up with Arctic news. You have attracted such a good crowd here that I can get a lot of ideas and info without crawling all over the web. In fact, you are doing what I was doing until I became unwell - but you do it more frequently and you get more comments. I hate you for that. ;-)

Petermann 2010-A has just gone walkabout. I managed to summon the energy to do a write-up. My next burst of energy will be devoted to soothsaying and prognostications about the Arctic's inauspicious portents. I thought I'd throw some big words out there to see if anyone's awake. ;-)

http://www.science20.com/chatter_box/petermanns_progress

Regards,
Patrick.

[Artful Dodger]

Petermann 2010-A (the larger piece) has moved out of contact with Joe Island, into the centre of the main channel of Nares Strait:

http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/201009191554.ASAR.jpg

[Andrew Xnn]

With most of the discussion focused on area, I'm curious as to where things stand with respect to volume. So, found this site that that's updated regularly. Note: it's presenting volume with respect to the 1979-2009 daily average:

http://psc.apl.washington.edu/ArcticSeaiceVolume/IceVolume.php

2010 has established a series new lows in volume anomalies.
September 2009 was the previous low volume at 5,800 km3.
However, it looks like 2010 is at least another 1,000 km3 lower.
So, we are looking at something like 4 more years to zero.

[Anu]

Meanwhile, in "Skeptic" World:

Sea Ice News #22 – melt season may have turned the corner
Posted on September 12, 2010 by Anthony Watts

How are they taking the news that the Arctic sea ice has set new minimums for 2010 all week long (on September 15,16,17 and 18 so far) ?

Pretty well - they're just ignoring it.

Looks like the Sunday weekly Sea Ice News is cancelled until the bad news goes away.

[Artful Dodger]

IJIS SIE for Sep 19 up 8,906 to 4,822,500 km^2. Don't panic! It's almost all from a wind event between Severnaya Zemlya and Franz Josef Land. This will actually create more melt, as the ice moves into warmer water. Just wait...

[L. Hamilton]

"What are you doing?"
"I'm watching ice melt, or not. It's really interesting!"

[JackTaylor]

AD, "the band plays on" for a good size upward revision to IJIS SIE of Sep 19.
Is the Fat Lady heading for the Taymyr (Taimyr) Peninsula across the Vilkitsky Strait?

http://webpages.charter.net/swf-test/gimg/extS07up.html

[Artful Dodger]

Haha, Jack. That's too funny! Do you take musical requests? How about Sull'Aria from The Marriage of Figaro. Cheers, mate!

[Guillaume Tell]

Anu: We have our own elephant in the room: this thread is a better place because the Arctic melt is bad news for deniers, so they don't leave comments here. And, I'm late to realize, because we aren't responding to them. But we can't ignore them completely.

Sea Ice News # 23 is now out, and suggests that the recent losses disappeared around Greenland (in apparent contradiction to CT's Greenland Sea area graphs). Then the discussion switched to around-Greenland export in the 2007 season. Note the animation's irrelevancy, since it is dated after 2007's minimum: from Oct 1,2007 to March18,2008.

They are becoming easier and easier to ignore.

[FrankD]

A week or two back we were talking about comparing the 30% CT area with the 15% IJIS area, to see if it was useful as a predictive tool. I posted some graphs before zapping off for a few days. Post in haste, repent at leisure or something...the more observant might have noticed that they were complete bollocks. I'd grabbed the wrong data set, and really just managed an upside version of Artful Dodgers "CAPIE" ...*facepalm*

So, apologies, and new graphs...with AREA this time...are here:
Delta (difference between CT and IJIS areas): http://img710.imageshack.us/img710/8017/dangerzonedelta.png
Percentage (Delta / IJIS Area: http://img838.imageshack.us/img838/5247/dangerzonepercent.png

The delta does not produce much useful information, it seems. The unremarkable 2003 tracks amongst the highest, while 2007 is consistently low. Doesn't seem a good indicator of future melting. Perhaps others will see indicators there that I missed.

I do note though, that the CT area is sometimes greater than the IJIS area, so clearly they are counting differently, apart from their cutoffs. The circular area at the pole being counted by one and not the other might explain some of it, but not all...

Percentage is a better fit. At first glance, the seasons with the big melts are clustered at the top, which one would expect intuitively. And there are some periods where a sharply rising percentage seems to be a good indicator of future melts :
In 2010, the sharp rise in late June - early July was a precursor to some big melts in late July; in 2007, a similar rise in late June heralded the big melts of July; 2007 and 2008 both show rises in August foreshadowing their relatively big late season reductions.

But as I suspected, its not great, and more would be required to tease out useful information. 2009 shows a big kick up towards the end of the season, but that doesn't herald more melting, just the early onset of the freeze up. 2008 also reached minimum early, and there is no obvious distinction between what you see when it was melting rapidly in August, or freezing rapidly in late September.

So I think its a bust. But not a complete waste of time - as the Duke of Wellington supposedly said of a failed campaign: "Well I learned how things should not be done, so that is something, at least."

[Steve Bloom]

That's funny, what happened to the traditional Watts hand-wave toward the ever-swelling Antarctic sea ice? Nary a mention of it.

[Werther]

Andrew, Lodger
I did some CAD work based on CT 23 sep 2007 and 18 sep 2010, scaling the lot on Google Earth (Bering St – Svalbard ca 3725 km). I drew high concentration (+90%, the reds and purples) and low concentration (15-90% the blues, greens and yellows).
The pixel-counters may be more exact, but 2010 has almost 200k less extent in the high concentration compared to 2007. Note that 2007 had very small low concentration extent (some 10 % of total SIE).
What could these observations tell us about volume? Lodger and Anu assumed .53-.83 cm overall thickness in july, guessing maybe .35 for the ‘slosh’.
My CAD gave 3.500k high concentration x 1.2 m1(?) x 95% conc. = 3990 km³ and 1.300k low x 0.35 m1(?) x 45% conc. = 204,75 km³.
I take it that 2007 cannot be seen as an exception, the situation now is even worse.
If possible, I’ll try to upload my CAD-picture as a jpg later.

[Christoffer Ladstein]

Andrew, Werther, Lodger (etc...): What really matters now is VOLUME. According to the 1979-2010 average from "Polar Science Center", the minimum 0f Sep. 2010, +- 4000km3 (if these numbers are to be correct!), is a staggering 70% loss from the 13400km3 Sep. average. We are literally threading thin ice!

Didn't I read somewhere that the icevolume in the Arctic probably never have been this "slim" since last interglacial...

[Neven]

AD, "the band plays on" for a good size upward revision to IJIS SIE of Sep 19

*makes note: definitely add music to animations next year*

Very funny, thanks. :-)

And well done, FrankD! Nice analysis. I'm sure it could be useful for something, but I'm too dim to think of anything right now. I have to keep repeating to myself what the CAPIE can tell us and how (melt ponds, compaction, etc).

[Peter Ellis]

FrankD: Nicely done, and I think we now have a winner as to the cause of the difference.

Note that the onset of the difference between CA area and IJIS area is around the start to middle of June. This is the point at which IJIS transitions between their "winter" algorithm and "summer" algorithms. The "summer" algorithm attempts to filter out the effect of surface melt ponding and give a more correct measure of extent / area.

If I had to guess, I would say that CA is not applying a surface melt correction, leading to much lower estimated areas during the summer months. If I'm right, look for the two measures to get closer to each other over after the summer minimum, and equalise around the middle of October (IJIS transition is around 15th October).

That would also explain why CA area has shown a bit uptick recently (melt ponds icing over) while IJIS hasn't (effect of melt ponds is already filtered out).

[Peter Ellis]

Is it worth contacting CA to check whether they use different algorithms for summer/winter ice area estimates?

[Neven]

PIPS is showing bigger arrows, but pointing the wrong way (more spreading out). Unless some miracle occurs, I don't think we'll see an extent decrease reported tomorrow:

[Neven]

CT area went down 28K.

[Phil263]

Even if the minimum IS 4.81 million sqkm, 2010 will have surprised beyond expectations! The new "minimum" is pretty close to Tamino's prediction of 4.78 million and puts 2010 only a hair's breadth above the quadratic trend.

[Artful Dodger]

Peter Ellis: Outstanding analysis, Mate! I do believe your onto something: We may have stumbled onto a metric for Melt Ponds. Now there's a testable hypothesis! I wonder how we'll use this... ;^)

FrankD: Thanks for doing this work, and for redoing it (some of my best stuff is done on the 10th try!). Seems to me that we should attempt to normalize the new statistic somewhat, so that the 'percentage' plot represents a proportion of the total ice covered with melt ponds. I'd suggest dividing (IJIS Area - CT Area) / IJIS Extent as the new statistic.

Peter or Frank: Have you thought of a name for this new Construct? Seems to me 'Top Melt' might capture the spirit and intent...

Iceman (Axel S.): Does your group have a name for what we're on to with this (assuming this is on to something ;^)

Neven: "PIPS is showing bigger arrows, but pointing the wrong way (more spreading out)

(hangs heads, clicks tongue)... "Spreading causes Melt; Compaction Preserves Ice" c.f. Wind event beginning Aug 27, 2010 for the effect of spread. For the effect of compaction, recall that the 2010 'Ice Arm' was formed in Summer 2007 near Franz Josef Land and has survived only because it was compacted fresh (old) ice.

Phil263: Tamino (and our own L.Hamilton!) are trying to estimate the NSIDC monthly mean for Sep 2010 (the Sep 18 daily value was 4.60 +/- 0.02 ). Given that T. and L. used two different approaches, it bodes well that they were so tight ( *although* Larry gave +/- error bars that would include most of the last 5 years. I didn't see any computation for those... ;^) See Neven's comments about the guidelines for SEARCH predictions.

[Voyageur]

my apologies for not being able to find it but .... can someone point me to ... or repost a plot of the quadratic trend referred to by Phil263

[Neven]

You can follow the link to Tamino's plot in Phil263's post, Voyageur.

[Neven]

Lodger, I thought Tamino's quadratic trend was predicting IJIS absolute/daily minimum. I just asked him and he confirms:

"My prediction was based on NSIDC mean September data, but was for IJIS absolute minimum. In other words, I used NSIDC September mean as a proxy for IJIS absolute minimum "

So he is really close, just 35K off.

[L. Hamilton]

Lodger, my error bars do look suspiciously wide. They equal the forecast plus or minus twice the standard error of forecast, estimated directly by the OLS model. That "default" approach seemed good enough for such a naive model.

One characteristic of OLS standard errors is that they become larger (signalling greater uncertainty) as you move away from the center and toward out-of-sample predictions.

Similar wide error bars occur if you use OLS standard errors with a quadratic regression model like Tamino's. He did not use the OLS standard errors, however, but made his own calculation based on the sample residuals. If I understand correctly what he did, that approach would not produce error bars that progressively widen as you move farther out.

[Artful Dodger]

Doh! that was a real grenade in the hen-house. SEARCH needs to make their guidelines upfront. How would you even guess he's estimating a statistic from a statistic. Bah!

[Artful Dodger]

IJIS final SIE for Sep 19, 2010: 4,841,563 km^2, for an increased SIE of 27,969
km ^2.

And now, more Musical requests for Jack ... ^;)

Since this is "2010", after all:
"New Worlds Theme" from 2010: A Space Odyssey 2
"Au Clair de la Lune" (the tune Hal9000 hums as he slowly fades away)

For Anu:
"Popcorn" - Kraftwerk

And please, throw Neven a bone:
Shakira - Waka Waka - Official Music Video of World Cup 2010

[L. Hamilton]

And to make my last comment slightly less opaque, OLS stands for "ordinary least squares" which is just the common type of regression analysis (as distinct from a hundred or so other types).

[Neven]

That's okay, Larry, I still don't understand. :-p

*must buy Statistics for Dummies*

[Lord Soth]

We have already gotten a double dip, and a triple dip to a new minimun is possible, I just don't think we will have the weather for it, and time is very quickly running out.

I'm quite confident that Sept 18 is the date for the new minimun.

Considering three weeks ago, it looked like we would not even break 5M km^2, this has been quite the accomplishment.

I expect the volume numbers to come in between 3900 to 4000 km^3 if I have done my math correctly.

Neven, if I understand you correctly, you just won't be posting after the end of the month. I assume you will not be taking the blog down. There is a lot of useful information, ideas and opinions in this great blog of yours. I would hate to see all this turn into a 404 page, when people go searching for it. Have you considerred a migration or archiving plan.

[L. Hamilton]

*must buy Statistics for Dummies*

Neven, I recommend this book instead ;^)

http://www.stata.com/bookstore/bi/rwgfront.jpg

[Neven]

LS, I won't take the site down completely. As it currently stands I'm waving off next week or so. After that, the blog will go in hibernation with some Open Threads, maybe an update here or there. Then, next year, if I have the time, energy and inclination I'd like to do another melt season, or else ask someone to take over. The main purpose was to create a central place for people to discuss the Arctic sea ice, instead of loose threads at RC, CA, or God forbid, WUWT. It'd be a shame to let that go to waste.

But I'll announce all of this officially.

Larry: 'A Second Course'? How about letting me do the first one first?

[Artful Dodger]

NSIDC SIE for Sep 19, 2010: 4.54 million km^2 (+/- 0.02)

Larry/Neven: never underestimate the power of the one-page cheat sheet:

http://www.dummies.com/how-to/content/statistics-ii-for-dummies-cheat-sheet.html

http://www.google.com/search?hl=en&safe=off&q=cheat+sheet+for+regression&btnG=Search&aq=f&aqi=&aql=&oq=&gs_rfai=

[L. Hamilton]

(I've got a bias towards that stats-book author.)

Lodger, do you get daily NSIDC values from their graph, or more directly?

[Artful Dodger]

Larry: No direct source, just interpolating from the public Chart. NSIDC gave out an individual daily value published on Climate Progress, so we can achieve +/- 1 pixel resolution with interpolation. 1 out of 57 pixels to 1,000,000 sq.km yields +/- 0.02 x 10^6 km^2 resolution.

Here's the C.P. article if you missed it earlier:

http://climateprogress.org/2010/09/18/arctic-sea-ice-melt-aint-over-til-its-over/

[Artful Dodger]

Sorry for the Part 2, Larry... On Sep 9 a C.P. post quotes NSIDC's Julienne Stroeve saying "We’ve dropped to 4.76 today." Here is the post:

http://climateprogress.org/2010/09/09/julienne-stroeve-nsidc-scientist-arctic-sea-ice-melt/

Joe Romm didn't include the Sep 9th Chart in that post, so here's a copy of the original on my drop site:

http://i785.photobucket.com/albums/yy131/arcticdodger/ArcticSeaIce/N_stddev_timeseries2010-09-09.png

[Neven]

Well done, Lodger! Hopefully NSIDC will decide to put out daily values next year. They are a bit hesitant because their numbers change due to missing data that later gets filled in, etc. That's understandable.

[Jon Torrance]

Having been silent for at least a few days, congratulations to L. Hamilton on a prediction in the August Search Sea Ice Outlook that's looking pretty good at the moment. But what really pleases me, after the long summer of WUWT heaping scorn on PIOMAS, is that Zhang's predictions based on the PIOMAS model look as though they'll have been quite accurate in the June outlook and probably slightly improved with the slight increase in July and August. They deserve some public vindication without having to wait for CryoSat-2 to deliver it.

[www.google.com/accounts/o8/id?id=AItOawn4S99JJRLrNfgA838BLqx0pzoN7lqRBgI]

The Fat Lady has sung. Look at the colours on the CT images, the compaction/ice growth has infilled the main mass.

[Artful Dodger]

Sorry, AItOawn. That new ice is 1-2 centimeters thick now, and presents absolutely no resistance to compaction. Go back to Sep 3 for a truer picture of what proportion of the Ice pack was open water, almost 40%. We've lost about 100 K of extent since then, mostly from compaction. Potential remains to loss up to another 200 K if wind conditions are right. There's really is no benefit to trying to call the end of the melt early.

[Neven]

You are absolutely right, Jon Torrance (good to see you comment BTW). Zhang and PIOMAS did much, much better than Goddard and his PIPS-based theory.

[JackTaylor]

"from a wind event between Severnaya Zemlya and Franz Josef Land. This will actually create more melt, as the ice moves into warmer water. Just wait.... Don't panic!"
Artful Dodger | September 20, 2010 at 05:08

A "Lodger" D, I will not bet against you. Some oscillation going on up there, recurring sine like curve in IJIS daily, if not too color blind and will squint the eyes to see my "stretched chart" the GRAY Line,
http://www.polk-nc.com/arctic-tenXten.html
not enough information available to me yet to say something like difference of high-low tides in the North Atlantic versus time differential of high-low tides in the North Pacific causing some sort of differential "sloshing" back and forth. Anybody have any information on sea level height variations in the Arctic when changing from a large high pressure to a low pressure causing thin ice to bend more than thick ice causing cracks to form channels for water flow beneath the ice, however in all three (3) of my enlarged animations thy show oscillation ... some expansion and retreat ... and I've almost convinced myself I can predict which way IJIS will report the next day by watching them.

Changed server address-URL because two of them are now over a MB each and it only takes 1000 combined hits to wipe out the transfer bandwidth of 1Gb per month.
IARC-JAXA http://webpages.charter.net/swf-test/gimg/arcA15end.swf
Uni-Bremen http://webpages.charter.net/swf-test/gimg/breA26end.swf
IARC-JAXA #2 with the band
http://webpages.charter.net/swf-test/gimg/extS07up.html

BTW, as for music requests, if I can source it royalty free with absolutely no copyright infringement will do, point it out for this "cultural bumkin" musical illiterate, I can make sounds ten different ways from Sunday.

Let's let the band play on until the show is truly over and they've turned out the lights.

[Artful Dodger]

Nice work, Jack. You asked: "Anybody have any information on sea level height variations in the Arctic". You can get weekly data for Sea Height here:

http://bulletin.mercator-ocean.fr/images/produits/bestproduct/bestproduct_20100915_22172/miv/arc/bestproduct_20100915_22172_arc_ssh_n0_t0.png

Weekly data might not help with your hypothesis, but you might get a signal if you look for select wind events where the DA / SLP zones where stable over a longer period... Good hunting!

[Artful Dodger]

PIOMAS has been updated as of Sep 15, 2010

http://psc.apl.washington.edu/ArcticSeaiceVolume/images/BPIOMASIceVolumeAnomalyCurrent.png

[Jon Torrance]

On reflection, I realise I'm not sure how PIOMAS deals with low concentration ice but the PIOMAS update and the JAXA extent for the 15th would seem to be saying the ice was slightly less than 90 centimeters thick on average. Less than that if the PIOMAS volume includes ice at less than 15% concentration.

[Werther]

This is the html version of the CAD graph comparing 2007 and 2010. Hope the conversion didn't mess it up too badly. The CAD version is nice for doing some calculations or playing arctic bathtub... As you can see, there is less high concentration extent than in 2007.

[Artful Dodger]

Lord Soth | September 20, 2010 at 16:37
"I expect the volume numbers to come in between 3900 to 4000 km^3"

Good job, you hit it right on the Bluenose! PIOMAS anomaly for Sep 15, 2010 was -9,500 km^3, and Sep 15 average volume is 13.4 km^3. The puts Sea Ice volume at *drum roll*:

3,900 km^3

In 1 year, Arctic has lost 1,900 km^3 of sea ice, which is a decrease of 34% of Sep 2009's volume of 5,800 km^3 .

If this loss rate holds, we've got 2 more summers left before the first ice free Summer.

Sep 2012.

[Neven]

Wow, Werther. Impressive!

If this loss rate holds, we've got 2 more summers left before the first ice free Summer.

Sep 2012.

The Mayans will be pleased to hear this. Our good friend Charles Wilson won't.

[Neven]

Werther, zou je die CAD-tekening naar me toe kunnen sturen? Dan zet ik hem op de voorpagina in een nieuwe blog post. Je kunt hem sturen naar mijn naam, apestaartje, spruitje, punt, com.

Handig dat Nederlands!

*apologies to all the non-Dutch for the impoliteness*

[Steve Bloom]

"If this loss rate holds, we've got 2 more summers left before the first ice free Summer.

Sep 2012."

The inevitable WTF headline: "Maslowski proven wrong!" :)

[Steve Bloom]

Re PIOMAS, to be fair ice-out would be in about 11 years based on their stated long-term declline rate, although I suspect Maslowski would still be vindicated since his projection includes a remnant and so would proibably be reached by 2019.

This drop from 5800 to 3900 in one year is impressive and bodes ill indeed for the immediate future, especially if as seems likely it's confirmed that the remaining multi-year ice is largely gone. I suppose we'll be seeing confirmation of this year's minimum volume as soon as the Cryosat 2 data is made public.

Dodger, are you eyeballing those numbers from the graph or is there an archive somewhere? I looked all over the site and can't find one.

[Andrew Xnn]

2012 is possibility...

However, the loss rate average over the last 15 years has been closer to 1100 km3. It's hard to say for sure if 2010 has established a new norm for loss rate or if there could be a shift back toward the longer term average. Either way, it looks like just a handful of year until we witness the first sea ice free arctic ocean in 3 million years. Of course, sea levels were 25m higher back then too.

[Lord Soth]

To give some perspective, 3900 km is roughly an ice cube slight less than 16 km wide by 16 km long by 16 km high. Thats a big ice cube when you first look at it, but it is rather tiny if you put in in the expanse of the arctic ocean.

[Steve Bloom]

Andrew, there were certainly summer ice-free periods in the mid-Pliocene ~3.3 mya, and maybe more recently, in particular during the long MIS-11 interglacial ~400 kya. This is no surprise since we can see how ephemeral it is under current conditions.

[Evilreductionist.blogspot.com]

I think a linear model for ice volume is not a good one. Maslowski talks about the ice going suddenly. This will, I believe, be proven to be a true statement. It will not gradually dwindle; it will suddenly just melt away. A very small increase in SSTs will attack the ice from below, and all we need is a warm Arctic summer to attack from the top simultaneously and ...

Map the change from 1997 or so until today. That is not linear.

[Steve Bloom]

Oops, I misread your comment, Andrew -- I thought there was a 1 in front of that 3.

While we're on the subject, everyone should memorize the recent results finding +19C temps in the Arctic during the mid-Pliocene with CO2 levels no higher than current and perhaps slightly lower. The most massive ice sheet is a candle in the wind under those conditions. Fortunately temps in the south stayed low enough that the East Antarctic Ice Sheet only took about a 20% hit. OTOH with CO2 levels very slightly higher, as during the mid-Miocene ~15 mya, it too will melt out, leaving just a remnant ice cap in the mountains and resulting in ~65 meters of sea level rise. What a gift for our descendants! On the plus side the Canadian Archipelago can be a refuge for any at-risk crocodilian species.

[Greg Wellman]

Steve, your "Maslowski proven wrong" joke cracked me up.

[Timothy Chase]

Arctic Sea Ice Volume Anomaly 2010-09-15
http://psc.apl.washington.edu/ArcticSeaiceVolume/IceVolume.php

If you are still seeing 2010-08-31 try:
https://docs.google.com/leaf?id=0B-57vongYoiAZWM0ZTc3ZjAtMmExYS00MmJhLTg4YWUtY2RmNWQ4MDJiMzM3&sort=name&layout=list&num=50

[Neven]

This time I saw the updated version straight away.

I have one question wrt the PIOMAS volume graph: there's an uptick at the end of it. What caused it? Is that because the melt didn't go so fast in July because of the DA getting interrupted?

[Jon Torrance]

"To give some perspective, 3900 km is roughly an ice cube slight less than 16 km wide by 16 km long by 16 km high. Thats a big ice cube when you first look at it, but it is rather tiny if you put in in the expanse of the arctic ocean."

The trick, of course, is to make the 16 km by 16 km slices wafer thin. Maybe we should start calling it Potemkin ice?

[Neven]

IJIS reports another increase: 4,855,156 square km.

[Steve Bloom]

Neven: Yes, although it's more than June was an extreme low followed by a recovery to something like the normal pace.

[Steve Bloom]

BTW, Neven, are these normal hours for you or are you getting up this early because of the blog? If the latter it's no wonder you need a rest!

[Anu]

@Artful Dodger | September 21, 2010 at 00:16

I get essentially the same numbers (zooming in at 800%, counting pixel ratios on the PIOMASS Volume Anomaly and Daily Average Volume graphs):
PIOMAS anomaly for Sep 15, 2010 was -9,500 km^3,
and Sep 15 average volume is 13.40625 km^3

so sea ice volume is 3.90625 * 1000 km^3, i.e. 3,910 km^3

Artful Dodger is independently confirmed :-)

Using Cryosphere sea ice area numbers:
http://arctic.atmos.uiuc.edu/cryosphere/timeseries.anom.1979-2008
the sea ice area for 9/15/10 is 3.1279442 million sq km
--> ~= 1.25 meters average thickness for the sea ice left on 9/15/10

Using JAXA sea ice area numbers (again, eyeballing the graph at 800% zoom and counting pixels):
http://www.ijis.iarc.uaf.edu/seaice/extent/AMSRE_Sea_Ice_Area.png
I get 4.074 million km^2
--> 96 cm average thickness for the sea ice on 9/15/10

[Neven]

BTW, Neven, are these normal hours for you or are you getting up this early because of the blog?

These aren't normal hours (6 AM over here), but I have a deadline for 9 AM, so I might as well enjoy myself in between. :-)

[Anu]

@ Neven | September 21, 2010 at 04:47

That uptick is pretty weird.
6/18/10 the volume anomaly is almost -11.
Then it jumps up on 7/17/10, and keeps climbing on 7/31, 8/16, 8/31 and a very tiny climb on 9/15.
The climb is almost 2000 km^3 of sea ice volume anomaly, relative to the average for 1979-2009.

http://www.ijis.iarc.uaf.edu/seaice/extent/AMSRE_Sea_Ice_Area.png
OK, June had record melts in area, and probably thickness too - but the next 3 months it looks like only 2007 really had 2010 beat for area by much - 2008 is almost right on top of 2010. So why did 2010 lose 2000 km^3 anomaly to the 30 year average over that time ? Just those little slope changes to the area curve ? Then why didn't the anomaly get bigger again for mid September ? Looks like that September slope is unique in the modern (post 2002) era.

Weird.
Well, we can't see what PIOMAS is calculating for thickness over the Arctic basin, and the area curve alone can't explain the volume anomaly curve.

[Anu]

To give some perspective, 3900 km is roughly an ice cube slight less than 16 km wide by 16 km long by 16 km high. Thats a big ice cube when you first look at it, but it is rather tiny if you put in in the expanse of the arctic ocean.
-- Lord Soth | September 21, 2010 at 02:23

The average depth of the Arctic Ocean is 1.038 km.
The deepest point is in the Eurasian Basin, at 5.450 km.
http://en.wikipedia.org/wiki/Arctic_Ocean

Seeing an ice cube, sitting on the floor of the Arctic, rising 15 kilometers in the air - that would be awesome.
Literally.

[Neven]

It is weird, isn't it? One wouldn't expect volume to go up during the melting season, especially not in July, despite the conditions at the time.

[Steve Bloom]

It seems highly unlikely that the volume actually increased at any point in the season. Possibly the shape can be explained in part by anomalies showing differnetly during high- and low-melt periods, although it being late I haven't thought that through completely.

[Werther]

Hi Neven,
I’ll send you the graph ASOP. I’m annoyed I forgot to change text at the last box, which should of course be read ‘high….’. And the yellow for ‘low 2007’ doesn’t fit well against the white background.
The 18 th September seems to have delivered the last CT-extent map that presented low concentration in blues and yellows in the main SI pack. Rapidfire shows on the 20 th that most ‘polynia’s’ (a lot…) have frozen over. But north of Svalbard you see that ice being cracked again, so winds, waves, tides must have lots of opps to continue doing damage to what’s left.
Lodger states that spreading results in fading. And it probably goes on into the formerly fast-frozen winterperiod. There’s so little mass left that the floes just won’t resist the mobility. Why would that be any different from the ‘thin’ first year ice around Antarctica? I think because the floes over there remain within the bounds of the south pole jet. In the Arctic they will move out into Lodger’s warmer, saline waters. So well into this winter the stage gets prepared for the fat lady’s swimming lessons next spring…

[Greg Wellman]

Note that the drop in PIOMAS volume (actual, not anomaly) from mid July to mid Sept for the "average" year is around 6 million km3. So this year had more volume melt before July than usual (putting it mildly) and less after. The anomaly could regress 2 million km3 towards the mean while actual volume was still decreasing (i.e. by 4 million km3 if I'm using the right time period, which I think I roughly am.)

[cynicus]

Andrew, Steve: I would like to know where you've got the info/data from that is the basis for "the Arctic was last ice free some 3 million or 400kyr ago" statement?

I'm sure the other side would otherwise just say "nah this means nothing, we're just measuring this for 50 years, so maybe the arctic was ice fee 200 years ago" or something to that extent...

[cynicus]

Neven, maybe the volume uptick is a anomaly similar to the discovery of rotten ice Dr. David Barber found where the satellites showed solid multi-year ice on his trips in the Arctic this year?

[Andrew Xnn]

"Dec. 30 (Bloomberg) -- Evidence that the Arctic Ocean was ice-free 3 million years ago, when average global temperatures were similar to projections for 2100, may shed light on how the far north will change as the Earth warms, a U.S. scientist said.

Fossilized shells recovered from the seabed show the Arctic Ocean was ice-free for at least part of the year during the mid- Pliocene era about 3 million to 3.3 million years ago, U.S. Geological Survey researcher Marci Robinson said in the journal Stratigraphy. The average temperature globally was about 3 degrees Celsius (5.5 degrees Fahrenheit) warmer than today, in line with United Nations forecasts for 2100, she said."

http://www.businessweek.com/news/2009-12-30/arctic-ocean-s-ice-free-past-may-shed-light-on-2100-study-says.html

and the technical paper found here:

http://www.micropress.org/stratigraphy/papers/Stratigraphy_6_4_265-275.pdf

And another paper on past sea levels and ice volumes:

http://pubs.giss.nasa.gov/docs/2009/2009_Dwyer_Chandler.pdf

[Anu]

@Greg Wellman | September 21, 2010 at 09:40
Yes, I agree that the volume probably never stopped decreasing during this period, and that the volume anomaly graph is showing what you describe. The weird part is trying to reconcile that with the sea ice area graph for 2010.

After that little plateau in late June:
http://www.ijis.iarc.uaf.edu/seaice/extent/AMSRE_Sea_Ice_Area.png
the sea ice area curve seemed to drop as quickly as all the other years, except 2007, whereas the volume anomaly kept climbing another 2000 km^3. Since 2010 was losing ground compared to the average for 1979 to 2009, not just 2007, this seems strange. Maybe every little bump in the 2010 area curve (decline slope going more horizontal) causes an uptick in the anomaly curve, since the average area decline is completely smooth.

And in late August, early September, the sea ice area curve for 2010 dropped more than other years, except 2008. Since we are comparing volumes to an average over 1979 to 2009, I would expect the volume anomaly to increase in late August/early September, based on this area curve.
Maybe years 1979-2001 had steeply declining area curves to a higher minimum sea ice area for July and August, so the average is steeper than the JAXA years - I'm just looking at JAXA data 2002 to 2010.

But as I mentioned, we don't know what PIOMAS is calculating for sea ice thickness in late August/early September in 2010 - maybe the thickness of the remaining ice was increasing then, since all the thin margin ice was melting, whereas in the previous 30 years, that thin margin ice usually survived (except in 2007).

[Anu]

The unpredictable Summer melt season is over tomorrow - last day of Summer.

Of course, there is a small possibility the first couple days of Autumn could do something surprising, too... but the Fat Lady is getting tired of encores.

The latest value : 4,878,281 km2 (September 20, 2010)

[Artful Dodger]

Sep 20 IJIS SIE: 4,878,281
Revision: +23,125
Daily Change: +36,718

[Artful Dodger]

A forecast wind event from now until Sep 25 is the best chance in the next week for further Sea Ice compaction in the E. Siberian 'Sea Ice Arm'.

A high-pressure system is forecast to pass over that area in the next 3 days. Easterly winds at 20 knot are occurring now and will persist over 24 hours. Winds gradually slacken until 12:00 UTC Sep 23, then switch to Northerly and increase sharply to 23 knots as SLP change reverses by 03:00 UTC Sep 24. Winds then gradually decline to 14 knots by 00:00 UTC Sep 25.

This UGRIB-generated graph shows forecast Winds and SLP at 76N 170E (the approx. centre of the Ice Arm) for Sep 21-28, 2010:

[Artful Dodger]

Anu: Actually, we do know what PIOMAS is calculating for sea ice thickness in late August/early September in 2010. Here is an animated Hindcast/Forecast of Arctic Sea Ice from Zhang and Lindsay, UWash: (the prediction of 4.8 M sq.km and the movie were updated on 8/5/2010)

http://psc.apl.washington.edu/zhang/IDAO/z.gif

[Greg Wellman]

Anu, I get what you're saying, but I wouldn't expect as tight coupling between area loss and volume loss. One can have above average area loss with below average volume loss if the area being lost was already very thin. Indeed year over year the opposite has been happening (a greater proportion of volume has been lost than area, by a lot). But as we get closer to zero volume, the rate of area loss will be shocking.

[Kevin McKinney]

Thanks for the animation, Lodger. The hindcast looks pretty accurate at first glance--for example, it captured the "East Siberian Ice Arm," more or less, and had about the right time frame for the disappearance of Hudson Bay Ice. What would be pretty cool in an assessment kind of mode would be an animation of the residuals between hindcast and observed ice coverage.

Greg, that makes intuitive sense to me (though I'm afraid that has sometimes proven a slender reed to lean on!)

[Artful Dodger]

NSIDC SIE reported a decrease in SIE to 4.52 million km^2 (+/- 0.02) on Sep 20. This is opposed to the increase in SIE reported by IJIS for the same day.

The difference appears to be in the E. Siberian Sea around 180 E. A change in Sea ice there that IJIS reports is not counted by NSIDC. Compare the Ice Edge between these two maps for Sep 20 from IJIS and NSIDC:

Please see Neven's 'Race to Fram Strait 5' post for the change in IJIS between Sep 19 and 20 (the animation is also available here).

[Neven]

Cool blink comparison, Lodger!

I've upgraded your IJIS animations one last time to Race to Fram Strait 6.

Does everyone agree the melting season is over? 4,813,594 square km on September 18th.

BTW, the AO Index has gone nuts (nosedived into negative territory), but the high is on the wrong side of the Arctic.

[Lord Soth]

That is amazing 4.52 on Sept 20 is the same as the 2008 minimun on Sept 14, 2008 of 4.52 million km^2.

Thats puts 2008 and 2010 in a photo finish tie for second place for NSIDC.

What are the chances of that (and don't say 100% because it already happened).

[Jon Torrance]

"Does everyone agree the melting season is over? 4,813,594 square km on September 18th."

I'm not committing to "over" - "almost certainly over" is my limit for now. Not that the PIPS displacement forecasts for today and tomorrow don't look awfully favourable to spreading rather than compaction but I haven't put in the work on the meteorological side of things to feel confident the medium range forecast doesn't hold a possible return to compaction so I'll want a bit more extent growth before declaring certainty.

[JackTaylor]

"Does everyone agree the melting season is over?
Neven | September 21, 2010 at 21:25

No, I'm with Jon Torrance. I need some more convincing, because when the first uptick on 29th August there was a down turn to 10th September with another uptick to 5,008,750 on13th September. When the current uptick of extent approaches or exceeds 5,050,000 will then be ready to sign on to a consent agreement. Will "Lodgers" eastery winds in excess of 20 knots cause more compaction or am I providing the 'hot air?'

[Neven]

I won't mind if you guys are right. Another extent drop would be extremely interesting to watch.

But I really do believe it's over. However, I do have a hunch that freeze-up could be slow. Maybe CT area anomaly could deliver a surprise, like dipping under 2 million square km.

[Anu]

Anu: Actually, we do know what PIOMAS is calculating for sea ice thickness in late August/early September in 2010. Here is an animated Hindcast/Forecast of Arctic Sea Ice from Zhang and Lindsay, UWash: (the prediction of 4.8 M sq.km and the movie were updated on 8/5/2010)

http://psc.apl.washington.edu/zhang/IDAO/z.gif

Posted by: Artful Dodger | September 21, 2010 at 18:06

Thanks AD, but there is a distinction between the actual Pan-Arctic Ice-Ocean Modeling and Assimilation System (PIOMAS) calculation of thickness based on measured forcing data (winds, cloudiness, ocean currents, some thickness data points, etc. that are all "assimilated" into the model for a current thickness estimate)

and using this model for inputing future, forecasted forcings to generate a prediction of future ice thickness.

Same model, different inputs.
The PIOMAS volume anomaly for 9/15/2010 on the Volume Anomaly chart is based on very current observations. The forecast made in early August is based on guesses (forecasts) of future forcings.

I think this thickness movie was made from actual, measured forcing data, not forecasts:
http://psc.apl.washington.edu/zhang/IDAO/summer2007_2008_arctic_seaice.gif

[Artful Dodger]

How come nobody is talking about SST's? 870x more is heat transferred from water-to-ice than from air-to-ice. The Sun isn't delivering substantial heat now, it's all coming from the water. To see how this works, look at Healy's Day-to-Night air temperature variance. It's all about the water temps.

Now 'compaction' season, that's another story! Bring on the Winds! or Freeze in Place, and we'll have a rapid melt-out in May 2011, and a huge head start for Septembers new record minimum. Or perhaps it'll be in Oct 2011 if the water heats up substantially more next summer...

[Artful Dodger]

Anu: the 'hindcast' portion of the animation is based on actual measurements. The 'forecast' portion is generated by the model as initialized by the hindcast values.

When Zhang and Lindsay update their animation so that the hindcast portion includes Sep 15, 2010 you'll have your thickness distribution data. I expect they will be a close fit to the Aug 8 forecast.

[Phil263]

Does everyone agree the melting season is over?
Neven | September 21, 2010 at 21:25

All over red rover ! I think. We are now past the equinox, I doubt that we wil have another 60k + drop that would give us a new minimum!

[Artful Dodger]

Lord Soth | September 21, 2010 at 21:26

"Thats puts 2008 and 2010 in a photo finish tie for second place for NSIDC.

What are the chances of that (and don't say 100% because it already happened)."

Remember, NSIDC ranks SIE by Monthly Average. So, if 2010 has a 'shallow' curve climbing out from the Minimum SIE, then 2010 will indeed beat 2008 for 2nd place.

[L. Hamilton]

JAXA's melting season looks over, and DMI's. NSIDC, Arctic ROOS, and Uni Bremen don't look totally convinced yet, perhaps they'll start climbing tomorrow.

[me.yahoo.com/a/nSjChi4X3vr8X3DRw93GkY1.cerja.8nvWk-]

For those interested both Northern Passage and Peter 1 are closing in on Pond Inlet, tomorrow would be my guess.

Phil.