Another month has passed, but this time there is more than just a data update. It seems the whole PIOMAS version 2.0 has been upgraded to 2.1. As it says on the Polar Science Center website:
We identified a programming error in a routine that interpolates ice concentration data prior to assimilation. The error only affected data from 2010-2013. These data have been reprocessed and are now available as version 2.1. Ice thickness is generally greater in the Beaufort Chukchi Sea area with the largest differences in thickness during May. Differences in ice volume are up to 11% greater in late spring.
Chris Reynolds has a blog post up on the Dosbat blog that explains the details and what they mean:
[T]he version change impacts overall volume very little. Note that all the following graphs are plotted using the full dataset from 1979 to 2013.
Wipneus has another interesting tidbit on the Arctic Sea Ice Forum:
[A]s a result of the version bump the trends have changed only slightly, especially when taking uncertainty into account. The exponential extrapolation to exactly zero, which was affected most, shifted upward 0.5 years (2016.44 to 2016.94).
With that out of the way we now proceed to the monthly PIOMAS update:
Here is the updated Arctic sea ice volume graph with data up to January 31st:
The gap with the three lowest years 2011, 2012 and 2013 has become considerably smaller in the past month, which probably has to do with relatively warm weather in the Arctic. The difference with 2013, for instance, has gone down from 1859 km3 at the end of the year to 1205 km3 at the end of the January. 2013 started out very low, but crept up a lot towards the end of the freezing season, reflecting a late cold snap that considerably thickened the ice.
This graph produced by Wipneus is a bit clearer:
I'm not sure whether the PIOMAS sea ice volume anomaly graph has also been upgraded to Version 2.1 (it says V2 in the file name), but the trend line is now well above the linear trend, when compared to last month:
With regards to average thickness (crudely calculated by dividing PIOMAS (PI) volume numbers with Cryosphere Today (CT)) nothing much has changed since the previous update:
Here's average thickness for January 31st in metres, with change from last month between brackets:
- 2005: 1.70 (+0.09)
- 2006: 1.69 (+0.16)
- 2007: 1.53 (+0.07)
- 2008: 1.55 (+0.13)
- 2009: 1.58 (+0.11)
- 2010: 1.54 (+0.13)
- 2011: 1.44 (+0.12)
- 2012: 1.48 (+0.18)
- 2013: 1.38 (+0.15)
- 2014: 1.52 (+0.16)
If you want to have a look at the data yourself, you can download the spreadsheet I use and update from GoogleDrive.
The Polar Science Center thickness graph basically shows the same thing:
So, we start the new year with a new version for PIOMAS, but this isn't the only recent news concerning sea ice volume and thickness. Somehow I overlooked it, but in December new CryoSat-2 data have been released, again showing how the cold and cloudy 2013 melting season caused a big bump in sea ice volume (see blog posts by Tamino and DiabloBanquisa for more info).
Updated gridded PIOMAS data have also been released last week, with Chris Reynolds deconstructing and reconstructing the whole thing on Dosbat, and Wipneus producing graphs for the Forum that show the difference with last year:
The difference is clear, especially north of the Canadian Archipelago and Greenland. Still, total volume difference isn't that big, and it will probably get smaller, given last year's cold snap, and relatively warm temperatures in the Arctic at the moment. If volume starts out around the same level of previous years since 2010, it remains to be seen how far last year's rebound stretches.
But that's impossible to predict right now.