One thing I failed to mention in the last SIE update and promised to get back to, is the fact that temperatures have been anomalously low on the Canadian side of the Arctic for quite a while now, or to be more precise: ever since the start of April, when the Arctic Oscillation that has been positive since the start of the year, became even more positive. It still hasn't let the Arctic out of its grip, which makes for vast cloudless regions over Greenland and the Canadian Archipelago. Great for clear satellite images, and obviously great for ultra-freezing temperatures.
I decided to go to the Daily Mean Composite page, compiled by the Physical Science Division of NOAA's Earth System Research Laboratory, that came in so handy when writing the End Zone series at the end of last year's melting season, and compare this year's April 1st - April 15th period with other years.This is the mean composite image for this year:
At a first glance it looks as though this year is less cold than previous years, as the dark purple blob is much smaller than in previous years. But that's because the scale is different! Except for 2009 the scale doesn't go below -15 degrees C, but this year the scale goes all the way down to -25 degrees C (unfortunately this happens a lot with these daily mean composite images, which makes comparing a tad more difficult). So at a second glance it looks as though this year has been 5-10 degrees C colder in the past few weeks than previous years in the period 2005-2010.
It's safe to say things have lately been mighty cold up there around Greenland and the Canadian Archipelago, keeping the Nares Strait frozen solid and thickening the ice between the Canadian Arctic islands some more before the melting season gets going. Will it be enough to keep the Northwest Passage from opening up this year? Somehow I don't think so, but it's too early to tell.
Sea surface temperatures
As sea surface temperatures probably play an even larger role in this, I decided to take a look at the SST anomalies for April on the EORC-JAXA webpage. This is the current situation:
Mind you, this year's SST anomaly map only covers the first half of April, whereas the other maps are for the whole month. Except for the very red Baffin/Newfoundland Bay in 2010, 2011 doesn't seem to be very different from other years. So far it looks very similar to 2005 (which is the only year in the 2005-2011 period that had an anomalously warm sea surface in the Bering Sea).
Keeping an eye on this gives us an idea how things compare to previous years and what might be expected the coming melting season, especially if we combine it with comparisons of sea ice thickness maps (I'm still waiting for TOPAZ to update, so I can compare it with PIPS). I'll do an update in a few weeks time. In the meantime: speculate!