Although the gap with 2011 and 2012 has become smaller, this year's volume is still quite a bit higher: 597 and 1139 km3 respectively (last month the difference was 1729 and 1720 km3 respectively). Apparently that one week of weather conditions that were conducive to ice loss allowed this year to catch up a bit. But the return of cold and cloudy weather can be seen at the very end of the trend line as well, keeping 2013 just slightly above 2010.
Last month I ventured to say that the cloudy weather could perhaps be throwing PIOMAS' parameters off, but the fact that these results echo what's going on elsewhere on the various area and extent graphs, makes me conclude for now that PIOMAS is still very much on the ball. I think that it's fair to say that this year's weather conditions have prevented a repeat of last year's massive volume drop during the first two thirds of the melting season. I keep harping on that melting potential and one must never say never in the Arctic, but the time for time to slowly run out has just about started.
Here is Wipneus'
version with the calculated "expected" 2013 values (dotted
lines), based on the same date values of 1979-2011 and an exponential
A caveat from Wipneus: "Note that the statistical error bars are quite large."
Instead of leaving 2 standard deviation territory, the anomaly from the linear downward trend has shot up again, a first since 2010:
Still, average thickness (crudely calculated by dividing PIOMAS (PI) volume numbers with Cryosphere Today (CT) sea ice area numbers) had a very steep drop in July, similar to the drop in 2010. This year's trend line is now lowest, probably signifying that the ice pack is spread out and thin at the edges (read: melting potential):
Here's average thickness for July 31st in metres, with change from last month between brackets:
- 2005: 2.38 (-0.09)
- 2006: 2.41 (-0.03)
- 2007: 2.15 (-0.04)
- 2008: 2.43 (+0.07)
- 2009: 2.06 (-0.05)
- 2010: 1.57 (-0.34)
- 2011: 1.56 (-0.19)
- 2012: 1.52 (-0.19)
- 2013: 1.48 (-0.23)
If you want to have a look at the data yourself, you can download the spreadsheet I use and update from GoogleDrive.
On the thickness graph from the Polar Science Center 2013 is now slightly above all three previous years:
Again, this year's weather seems to have been influential enough to stop the year-on-year drop in volume, which could lead to the same type of situation after 2007, where a very large drop was followed by a bounce or two. But let's wait another month or two before drawing any definitive conclusions.