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Werther

Well, there it is... most of a central pack about 3,2MK around 0,9 m thick... They found some MYI, a bit more 'fleshy'. The Cryosat2 team has a lot of adjusting to go through.
Meanwhile, Hamilton presented a volume around 5000 kmĀ³ for 31 july, based on PIOMAS daily data. But there's a lot of evidence that the total volume has indeed neared or even passed 4000. Heading for less, as predicted.

Andrei Saviankou

Could you good people of the know, please, elucidate why is PIOMAS graph of the ice volume has had this up tick from the middle of the summer times and how it is at all possible for the ice volume to go up bearing in mind the timing of their latest update ?
And also can anyonbe, please, explane why are methane concentrations are counterintuitively seasonaly going down in summer when all the tundra vegetation is rotting away.
Thanks in advance to anyone who can

crandles

The PIOMAS uptick is on the anomaly graph. So volume is going down just not as fast as usual for July.

If you download the data the last several days show:
2011 190 10.029
2011 191 9.81
2011 192 9.629
2011 193 9.448
2011 194 9.265
2011 195 9.067
2011 196 8.9
2011 197 8.735
2011 198 8.558
2011 199 8.394
2011 200 8.229
2011 201 8.057
2011 202 7.899
2011 203 7.702
2011 204 7.531
2011 205 7.405
2011 206 7.264
2011 207 7.112
2011 208 6.993
2011 209 6.856
2011 210 6.727
2011 211 6.607
2011 212 6.494

I think we can agree that is going down.

Why not as fast as usual seems a more difficult question but is probably a combination of 1) weather related, 2) noise and 3) less area than usual at low latitudes to have a go at melting, and a few other reasons.

L. Hamilton

Anomaly graphs, including PIOMAS, tend to highlight small differences between years. A graph of absolute PIOMAS volume estimates vs. day in July shows the progression this year generally resembled that of previous years -- except there's less ice. Only 2010 comes close, 2007 has been left far behind.

http://img.photobucket.com/albums/v224/Chiloe/Climate/sea_ice_PIOMAS_July.png

Frivolousz21

So either Cryosat is right and we lost an incredible amount of ice this summer through melt or it was way off.

Bob Wallace

Would someone summarize the Cryosat issue for those of us with limited knowledge? Or point to a good site?

Neven

Bob, here's some info on this here blog when the first map was released at the end of June.

The 'issue' with Cryosat-2 was that this first map seemed to show thicker ice than what the ice thickness models were showing.

This is how I see it (I copy my last comment from that thread):

"I've been discussing this with a few people through mail. Everyone says the same (and it took me a while to get it): More data is needed for a longer time series, calibration is an ongoing process. So we need to be patient for a while longer.

But I agree with you that there are some inconsistencies on this map for Jan/Feb 2011. We'll see how it pans out. They obviously wanted to show something at the high profile Paris Air and Space Show. Which is perfectly understandable, of course.

However the definite thickness maps turn out (either confirming or disproving models, or something in between), I'll be extremely happy to have more certainty when it comes to thickness and volume."

Frivolousz21

The 12z GFS shows an even stronger DPA that would cripple the arctic and possibly send the extent into the 3.5-4.0 range.

both the Euro and GFS have showed this for 3 days now.

Michael Stefan

If the average ice thickness over the entire Arctic was only 0.9 meters, then that means that ice volume would be only 2,900 km3, based on current CT ice area of 3.23 million km2. At that rate of decline, it would reach zero in a few more years...

Wayne Kernochan

Let me add my own uninformed opinion to @crandles re the July uptick in the volume anomaly. As heating increases year-round in the Arctic, showing up in temps under the water and sun/temps in the air, you would expect the under-water increase in heating to be relatively steady year-round. However, you would expect the air heating-caused volume anomaly increase to be greatest when the sun is directly overhead and shining all the time, i.e., in June and July. Note that just about exactly the same thing happened last year -- except that this year the anomaly was even greater in June and July compared to last year if I'm reading the chart correctly, and the decrease in the anomaly from June to July was less than in 2010. Not a good sign. - w

crandles

Michael Stefan

If the average ice thickness over the entire Arctic was only 0.9

Unlikely I believe. 0.9m is not far off what PIOMAS is showing for now

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

That seasonal outlook at http://psc.apl.washington.edu/zhang/IDAO/seasonal_outlook.html
is out of date but I doubt the update is much different.

D

Mostly, Arctic methane sources are small and far between. These days permafrost methane releases are on the order of 1m tonnes per year compared to the 90m tonnes of methane from tropical wetlands and rice production. However, between 2003 and 2007 Arctic permafrost methane releases increased at ~6% per year. (http://www.sciencemag.org/content/327/5963/322.abstract )

Our Arctic air sampling stations are also far apart. A methane source must be rather near a particular sampling station and the wind must be blowing in just the right direction to get a significant increase on concentration. Our sampling network is just not dense enough to give a good picture of what is going on with methane in the Arctic.

Andrei Saviankou

Thank you very much D, Crandles, L Hamilton for explanations

Daniel Bailey

In the most recent Healy image, it looks like they have imaged the Canadian vessel they are doing operations with (Starboard foreground here). FWIW

Seke Rob

An interesting blog entry of September 2 discussing the ice thickness measurements from 2 helicopter and the methodolgy and calibrations to ensure 10cm accurate measurement. They did encounter ranges of up to 10M thick MYI.

German original:

http://www.geo.de/blog/geo/polarstern-blog/wissenschaft/eisdickenmessungen-aus-der-luft

Google translated page link:

http://translate.googleusercontent.com/translate_c?hl=en&ie=UTF8&prev=_t&rurl=translate.google.com&sl=auto&tl=en&u=http://www.geo.de/blog/geo/polarstern-blog/wissenschaft/eisdickenmessungen-aus-der-luft&usg=ALkJrhjOxdrS37cP_2_Hk2xZ0gSUw2iFkQ">http://www.geo.de/blog/geo/polarstern-blog/wissenschaft/eisdickenmessungen-aus-der-luft&usg=ALkJrhjOxdrS37cP_2_Hk2xZ0gSUw2iFkQ">http://translate.googleusercontent.com/translate_c?hl=en&ie=UTF8&prev=_t&rurl=translate.google.com&sl=auto&tl=en&u=http://www.geo.de/blog/geo/polarstern-blog/wissenschaft/eisdickenmessungen-aus-der-luft&usg=ALkJrhjOxdrS37cP_2_Hk2xZ0gSUw2iFkQ

Neven

Seke Rob, I was planning on doing a blog post on this as soon as I find the time (maybe tonight).

Seke Rob

The 2012 Fahrplan for the Polarstern, since May 16 back in Bremerhaven: Polarstern 2012 Trip Plan

Several trips to Fram Strait on the board, first departing tomorrow and an August visit to the Arctic ocean. Follow the ships weekly log at Polarstern Weekly Log updates [and use Google translate who needs to].

-- Rob

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