A minor fuss has errupted over ERA40 reanalysis data at Arctic latitudes so I thought it would be useful to post how I see some of the data.
[EDIT: SERIOUS ERROR CORRECTED, untested software, mistake by me, had an incorrect weighted mean showing a grossly small temperature range]
This pair of plots were produced here from gridded data for circles +70 latitude to the poles. UAH data does provide what seems reasonable data. Data to July 2011.
As with the south pole station data there is zero temperature change for Antactica.
Various results are possible for the Arctic and elsewhere I showed a reasonable inverse match between sea ice and UAH TLT temperature.
In private I have posited the idea that earth temperature wobbles around a pivot at the south pole but this is not shown. We need much longer data to see how true that is. There is agreement between satellite and HADCRUT3 but the latter shows signs of severe internal problems if the clock is wound back far.
I think there is plenty of evidence supporting a view of cyclic Arctic change, including in formal papers.
How the plots were done
Some time ago I knocked up some scripting software which processes published gridded datasets into a common format. Various processed output is provided.
In this case all latitude bands pre-weighted are output, a large grid of time series. It is then a simple matter to compute a combination.
(for UAH the outputs are exact clones of published, ie. the math is the same and for UAH there is no missing data)
One thing I have never done is figure out a list of latitude/longitude pairs for extraction which match known sea ice.
There is some question over the validity of polar data from these satellites given the poor view. Odd is that it works even during winter total darkness but the rough sensing altitude is 15k feet where maybe there is still enough light.