Monday, December 14, 2009

Interesting Features

In his blog post, Giorgio Gilestro claims to show that the adjustments made by GHCN to temperature data do not induce  artificial trends into the data based mainly on this histogram of adjustments.

Finally, these averages were again averaged over the stations to calculate an average for each year.:

The graph has some interesting features.  First of all, there is a fairly linear trend from about 1900 to the present.  The increase is about  0.25o.  A second unexpected feature was the fact that there seems to be a fairly constant reduction of 0.10o C from about 1990 to 2006!  The expression “hiding the decline” comes to mind and I believe this would need some sort of explanation.

Since posting this yesterday, I have become aware of a post doing a similar analysis   by blogger hpx83.  His results are basically the same as the ones I have posted.  However, using further information about  the stations, he has also included a graph of the number of stations available in a given year:

Posted by at