Thursday, December 10, 2009

Reconstruction of the 1850 to present day warming trend from Met Office data

Having got the gridding working of the recently released Met Office Land Surface Temperature data it was a short step to reconstruct the temperature trends for 1850 to the present day.

I've performed the same gridding as the HadCRUT3 dataset with one exception: I have not removed outliers (the papers on the subject describe removing outliers in the anomaly data that are greater than five standard deviations from the normals). I've left outliers in just to get a feel for the data as is, without clean up. That means that the graphs below are a bit more noisy than in the published literature, but the warming trends are clear.

Here's the northern hemisphere chart:

and here's the (less dramatic) southern hemisphere chart:

and here's the global chart (which is taken by averaging the north and south on a month by month basis):

1 comment:

Pádraig Brady said...

Note gnuplot 4 produces much nicer antialiased graphs if you "set terminal pngcairo" or if that's not compiled into your build you can output to the default gui window and copy to the clipboard from there. There are some examples here: