I’ve been fascinated over the last couple of months with the arctic freeze up. I’ve been following the sea ice increase from Cryosphere Today, a nice site made by University of Illinois. I’ve been taking screen caps each day and every morning I have my coffee and see where the ice has grown from the previous day. Then I look at the water temps, air temps, water depths and try to reverse engineer why the ice grew where it did. It certainly has me brushing up on my arctic geography. I was probably the only one on my block this week who got excited that Jenny Lind Island finally was ice connected to Victoria Island.
What I have noticed in just a few weeks of attention is how distinct the arctic regions are in terms of the dynamics of ice. I was used to thinking of the polar ice cap as a single thing but watching the different speeds each part grows has altered that. This thinking led me to look at the differing regional expansions and contractions of the ice in the last year. What I found was that rather than just a monolithic thing that got small in summer and large in winter, the different regions wax and wane independently at all times of the year.
I compared 13 regions against their own 1979-2008 mean (the satellite era.) I recorded when the area was at its lowest below mean and highest above mean during this past year. It may surprise some to know that every region had a period this year when it was above the mean. Here is a quick map of the regions I will make reference to.
Some interesting observations from Jan 2010-Nov 2010
* The Sea of Ohkotsk was lowest below mean in the same month the Bering Sea was at its highest above the mean. Curious since they are so close.
* The Barents Sea was lowest below mean in the same month the Kara Sea was highest above mean. These two seas are beside each other.
* The East Siberian Sea was lowest below mean while the Greenland Sea and Baffin Sea were both at their highest above mean.
* Hudson Bay was lowest below mean in the same month that East Siberian Sea was highest above mean.
There are many more of these simultaneous maximums and minimums. Of course the value of the minimums are different and the size of the regions are different. By adding it all up, the entire arctic is below the 1979-2008 average. What this regional perspective shows clearly is that there are very different mechanisms affecting the different regions. Most image and area data I encounter are aggregate totals. This makes the regional mechanisms less obvious and gives the appearance of monolithic forces.
To best appreciate the ebb and flow above and below mean in each region this year, I included the data for each region below. It’s pretty interesting just how different the dynamics are. Also interesting is just how fast a region goes from below average to above average. For example, the Kara Sea went from 400,000 square km below average to nearly 100,000 square km over average in just 6 weeks! This amazing dynamism gets lost in the larger averages.