We are entering the final phase of the melting season. Extent decrease rates are getting lower and lower and soon we will start seeing the first days of extent growth, followed soon after by minimum extent. I figured it might be interesting to have a look at what happened in other years, specifically the years of the 'new Arctic era': 2007, 2008 and 2009. Perhaps we'll see some parallels that give us an idea of when and how the 2010 melting season will end.
I have downloaded a lot of images from different sources and combined them to make animations of the period August 25th-September 24th. The final date is based on when 2007 reached minimum extent.
This is the final End Zone instalment (unless someone proposes some other aspect that should be covered). Previous instalments were:
- End Zone 1: air temperature
- End Zone 2: ice displacement
- End Zone 3: atmospheric pressure
- End Zone 4: sea surface temperature
For sea ice concentration I downloaded images from the excellent University of Bremen archive. Although I sometimes dislike the fact that these maps have a tendency to suddenly blink whole swathes of green and yellow colours (arousing the alarmist in me) and then blink back again to high concentration pink and purple, these images are still one of the best to monitor and work with IMO.
So, let's have a look:
The animated triptych is a bit too big to fit on most computer screens, but if I make it any smaller the resolution will be too low, I fear.
There's not much more I can say about these images than the obvious: 2007 got compacted a lot because of that persistent Arctic Dipole Anomaly and thus we see high sea ice concentration all through the remaining ice pack. The pack gets smaller and smaller at the edges, all the way until minimum extent is reached on the 24th of September.
2008 initially has more regions of ice with low concentrations, but these get compacted and refreeze during the first week of September and disappear completely after September 10th, the date minimum extent was reached. Or actually I should say September 11th, because of the leap year. The same more or less goes for 2009 that has a similar shape to 2008, but with a bigger bulge towards the Chukchi Sea.
And how is 2010 looking from August 25th onwards?
The shape looks quite a bit like that of the ice pack in 2008, but with a large part of that ice pack protruding into the East Siberian Sea. It remains to be seen if that ice will melt out as it consists of multi-year ice that was transported there last winter. Another thing to notice is the large swathes of yellow and green within the central ice pack, especially towards Fram Strait. These are not blinking so much, so I think 2010 has some great compaction potential. But it all depends on the winds now (and to a lesser extent SSTs).
I think 2010 has some elements of 2007 (high SSTs, maybe atmospheric patterns for the coming 10 days), but some elements of 2008 as well (general shape, maybe atmospheric patterns for the coming days). Two to three more weeks and we'll know everything!