WUWT readers may recall a couple of weeks ago that I suggested that the weather stations with different climatic influences of the Antarctic peninsula, which might very well merit its own separate climate designation from the Antarctic mainland, was heavily weighting the Steig et al results ( Nature, Jan 22, 2009). Essentially that weighting “gobbled up” the trends on the mainland, such as the trend at the south pole station which shows a long term cooling.
Jeff Id took that advice and did an analysis which I have reposted by invitation below. But, I just couldn’t help notice that this graph below looks a lot like Jeff’s results 
.
Above: Peninsula Pac-mann gobbles up the trend. See Figure 8 in Jeff’s analysis.
Antarctic Warming – The Final Straw
Guest posted by Jeff Id of the Air Vent
This is the first post I’ve done which gets to the heart of where the trends in Steig et al. came from. Steve M did a post on TTLS reconstruction TTLS in a Steig Context which makes the point that despite the PCA and truncation the result of RegEM is still a linear recombination of station data. This post is the result of a back calculation of station weights to determine which stations were weighted and by how much to create the final trend of Steig et al.
Before I succeeded in this calculation yesterday, I tried it once before some time ago and it didn’t work. There were a couple of errors which prevented me from getting a solution and I was too lazy to fix it. The Climate Audit post pushed me to try again and this time I got it right. I think you’ll find the result a bit telling.
The satellite reconstruction from Steig et al is based on two halves. The pre-1982 half is entirely surface station data, the post 1982 data is satellite based data. The satellite half is easily replicated from the satellite data while the surface station half is simply a linear weight and sum of the surface stations. If the surface station temperature is SST, and the weights are c the net result of all this complex math prior to 1982 looks like this
T output = (C1 * SST1) + (C2 * SST2) ……. (Cn * SSTn)
That’s it!
So in order to calculate the C’s involved in this equation we can back solve a series of linear equations having the form above. There are 42 SST’s in the reconstruction and 1 Satellite trend. Since the satellite is not used pre-1982 we can ignore that for determining the pre-1982 portion of the reconstruction. So we have 42 SST’s but not all of those have any data before 1982. After removing the stations which don’t have any pre-1982 data only 34 remain. These 34 are the only ones mathematically incorporated in the reconstruction and are shown in Figure 1.
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