No, this is not a review of one of the Disney sequels. Fredt34 sent me a mail to draw my attention to this ice analysis map from the Arctic and Antarctic Research Institute from St. Petersburg, Russia. This institute had some great weekly sea ice displacement forecast maps last year, but unfortunately the web page went down in the middle of the melting season.
This ice analysis map is nice too, though, as it gives us an idea of the age of different parts of the ice pack, which is why I think this blog post will fit in nicely with the recent string of posts on sea ice thickness.
Here's the current situation according to AARI (click for a larger version):
The light blue shows where the open sea is, and the dark blue is for water covered with Nilas (very thin ice). The pink is for young ice between 0-30 cm thick, and the green is first-year ice with a thickness of 30-200 cm. The brown colour for olde ice that survived at least one melting season, is what interests us most, as all the other colours will probably melt out this season.
To us Europeans and Americans this image might look like it's upside down, but that's because it's from a Russian perspective. They are perfectly entitled to do this. In fact, I'll even flip this Arctic sea ice age figure from the NSIDC March analysis (courtesy of J. Maslanik and C. Fowler from the University of Colorado) so it's easier to compare:
They correspond pretty well with each other. I think we are seeing a remnant of the Arm that has survived last year's melting season and stretches all the way to the Siberian coast. And another baby arm that has started to develop along the Alaskan coast in the Beaufort Sea. One other thing I notice on the AARI map is that some of the first year ice is very close to the North Pole. Of course things will be moving around a lot as the meting season progresses, but who knows, perhaps we'll see that ice-free North Pole that Mark Serreze and David Barber talked about a few years back.
All of this is less pronounced on the Maslanik map because March is a month and a half behind us now. Apparently the spread of the ice of different ages isn't static and the total area of the oldest ice gets smaller, probably due to compression. To illustrate this I have made an animation of AARI sea ice age images from this year so far:
Unfortunately the AARI archive doesn't go further back than December 2007. This year is looking slightly worse than last year, but much better than 2008 and 2009. Of course, ice age used to be a pretty good indicator of ice thickness, but we can't be sure how thick the multi-year ice is until CryoSat-2 data is finally calibrated and...
Darn it, I keep repeating myself! CryoSat people, take your data, stuff them in your Twin Otter and fly back to your computers, now!