As promised I'm returning to the sea ice thickness models I wrote about two weeks ago, highlighting some of the current differences between PIPS, PIOMAS and TOPAZ. The satellite that will give us a definitive answer on ice thickness and volume, CryoSat-2, is currently being calibrated with the help of surveys by ESA and NASA. It will take some more time before definite data will be made publicly available, so in the meantime we'll continue looking at what sea ice thickness models have told us so far.
PIPS 2.0 2004-2011
PIPS 2.0 (Polar Ice Prediction System) has an excellent archive, so I have retrieved all the ice thickness images from the period 2004-2011 and put them side by side (click for a larger image):
This year the overall sea ice thickness seems to have almost returned to levels last seen in 2004 and 2005. I'd be surprised if this were true, considering the fact that last winter was pretty mild, and of course the fact that we've seen some pretty dramatic shrinking of Arctic sea ice extent in the past few years. Although multi-year ice has recovered somewhat in the past 2 years, levels are still 10% below those of 2005:
Some other thing I mentioned in passing in yesterday's blog post on the situation around Franz Josef Land, is that PIPS seems to project 5 meter thick ice where there is in fact open water and/or a slush of small ice floes. The same goes to a lesser extent for those red dots off the coast of Alaska and northwest Canada that do not seem to be confirmed by satellite images.
But at least most of the really thick ice has disappeared from the channels in the Canadian Archipelago according to the PIPS ice thickness model, which seems to be consistent with the transport of sea ice we witnessed last year in places like Ballantyne Strait and the Prince Gustaf Adolf Sea.
Unfortunately the TOPAZ model (delivered as part of the MyOcean project) doesn't go back such a long way as PIPS, as it is a much more modern model. But I still managed to retrieve images for 2008, 2009 and 2010 from their old site and made a composite image from their brand new dynamic viewer (click for a larger version):
The scales differ somewhat, but this year resembles 2009 most in that there is hardly any thick ice on the Siberian side of the Arctic. Most of it is pressed against Greenland and the Canadian Archipelago (but again, not in it, in contrast with previous years).
I have discussed some of the differences between TOPAZ and PIPS in the previous post on sea ice thickness models, so there's no need to do it here (but do not hesitate to comment if you think I've missed something, because I always do). Unfortunately there is no archive of PIOMAS images. The only thing I have is the animated GIF I included in a blog post from last year.
I don't have much circumstantial evidence, and would love to hear from others who managed to pick up some tidbits here and there. One thing I found on the ESA CryoSat blog was a mention of them directly measuring a thickness of 1.80 meters at 85.6° N 69.8° W, which would be approximately where the white dot is flashing:
After asking for some more info on their direct measurements of sea ice thickness, CryoSat validation manager Malcom Davidson replied:
Still working on the data. However as a rough indication first and second year ice were 1 – 2m thick at the two sites (85.6N and 69.8 W and 83.3 N and 62.9 W) and multi-year ice highly variable from 2m to 6m or more.
So there you have it. Checking out the Arcus data resource page I came across this 'Graph of Ice Thickness Initialization Field Used for Ensemble Simulations in 2010' from the Alfred Wegener Institute:
What happened in the Arctic last week is old news.
UPDATE May 15th
Scientists from the Alfred Wegener Institute have done another survey of parts of the Arctic, as was reported by commenter Chris K. a few days back. This survey was also done to support ESA and NASA operations for validating CryoSat-2 sea ice thickness data. One other commenter, Enno Zinngrebe, was so kind as to translate the part that pertains to this blog post, another piece of circumstantial evidence on actual ice thickness:
A preliminary look at the measurements shows that the one-year ice in the Beaufort Sea () this year is 20-30 cm thinner than in the previous two years. The ice thickness was in 2009 on average 1.7 m, in 2010 on average 1.6 m, and 2011 on average 1.4 m.
ScienceDaily now has an article on this.