I'm regularly writing updates on the current sea ice extent (SIE) as reported by IJIS (a joint effort of the International Arctic Research Center and the Japan Aerospace Exploration Agency) and compare it to the sea ice extents in the period 2005-2009. The IJIS graph is favoured by almost everyone, probably because it looks so nice compared to other graphs (like the one by Arctic ROOS, the University of Bremen and the Danish Meteorological Institute). All the years have a nice colour of their own which makes it easy to eyeball the differences between trends. Most of the betting on minimum SIE is based on the IJIS data. NSIDC has a good explanation of what sea ice extent is in their FAQ.
September 15th 2010
Let's leave the playground metaphore for a while. Let's leave the seesaws, the swings, the slides and the trampolines. Let's go back to the fat lady. She's singing alright, but who is she and what's the song she's singing?
Sorry, couldn't help myself. Click 'play' and continue reading.
After slowing down a bit the extent decrease turned into an increase of 50K over the past 3 days, but atmospheric patterns are very fickle. Three days of weird weather, winds blowing towards the pole, and some of that compaction potential could be put to work. Despite the freeze-up kicking into gear, we still might see a slightly lower minimum extent. Keep an eye on the updated animations of the western and eastern Arctic.
The current difference between 2010 and the other years is as follows:
- 2005: -524K(10,313)
- 2006: -783K (11,473)
- 2007: +707 (20,234)
- 2008: +256K (24,632)
- 2009: -278K (14,096)
Between brackets is the average daily extent decrease for the month of September until this date. 2010's average daily extent decrease for September is currently 23,627 square km per day.
If 2010 loses as much sea ice extent as...
- 2005 did after this date it will bottom out at 4.79 million square km.
- 2007 did after this date it will bottom out at 4.96 million square km.
All the other years had of course bottomed out by now.
Here's the IJIS sea ice extent graph:
Cryosphere Today sea ice area has increased quite a bit and will probably not drop below the 3 million square km mark. It currently stands at 3.128 million square km. The anomaly compared to the 1979-2008 mean is still relatively big though and could increase some more to accentuate the double dip we witnessed this year:
The increases in area combined with the decreases in extent are starting to show on our CAPIE (Cryosphere area per IJIS extent) graph. The 2010 trend line is likely to go up now, showing that there might finally be some real compaction going on. How much is hard to tell as at this point water between ice floes is also freezing up here and there. The CAPIE percentage is currently 62.58%:
One counterintuitive sign that the freeze-up is starting for real is increasing air temperatures. This is because the water has to release its heat to the air before it can start to freeze up. The DMI graph of air temperature north of 80 degrees latitude is showing this first uptick:
Like I've said ever since the End Zone series the PIPS ice displacement maps are one of the best indicators of extent increase/decrease in this final phase of the melting season. Unfortunately the images weren't updated for a couple of days, which made it difficult to know if the ice extent would increase or decrease (although weather maps were suggesting the former). In hindcast the PIPS ice displacement maps were showing clear signs of extent increase in the shape of smaller arrows pointing in different directions. In 2008 and 2009 this had meant the melting season was over, but with this year's higher SSTs it's not definite yet.
Here's an animation of PIPS ice displacement maps from the last 7 days. As you can see, arrows have gotten bigger again in the past two days, meaning we might see another day of extent decrease:
It is really hard to tell in advance what atmospheric patterns we can expect in the coming few days. The high and lows are battling it out in the Arctic, with systems continually shifting positions. According to the ECMWF forecast model a high-pressure area is positioning itself again over the Canadian side of the Arctic. This is one of the prerequisites of compaction and ice transport, but as it extends itself over the central Arctic it might interfere and prevent the setting up of a proper Arctic Dipole Anomaly.
Some very big cyclones are forecasted to form all over the place, so there's no telling really what might happen. But with the return of high-pressure areas there is at least a possibility of further extent decreases. A last wisp of excitement and anticipation at the end of the melting season.
TIPS - Other interesting blog posts and news articles concerning the Arctic and its ice:
Again, don't forget those animations of IJIS sea ice concentration maps of the western and eastern Arctic. They are updated every 1-2 days. The small ice pack in the East Siberian Sea is on the move.
Tamino has a short post on the Death Spiral, showing his quadratic trend. I fully agree with the conclusion: Anyone who calls it a “recovery” is lying, either to himself or to you, and is not to be trusted about matters relating to global warming.
Joe Romm meanwhile is one step ahead with this exclusive and already looking forward to the big questions that pop up now that the melting season is at its end. How did the multi-year ice do? How thick is it? Volume, anyone? The Lord praise CryoSat-2.
I noticed an interesting blog linking to this one: Arctic Progress. This site by Anatoly Karlin aims to provide Arctic news and the best analysis of the region’s economy, energy and security on the Web drawing on English and Russian sources.