U.S. temperatures and the BEST study

For those who have been following my review of the temperatures around the United States, there was an interesting set of papers released by the Berkeley Earth Surface Temperature (BEST) study in the last week. Four sets of findings have been released, based on:
1) statistical methods
2) Urban Heat Island
3) Station Quality
4) Decadal Variations.

For the moment I am most interested in the second of these, since it relates to the effect of population around the measuring station on the resulting temperature reported. This is not quite the same as the UHI effect, although they are both generated by the same factors.

In the paper, to greatly over simplify, the authors appear to have looked at the trends in temperatures in urban and rural sites, and then looked at the difference between the trends in temperature since 1950 for each. They report that the overall trend (i.e. temperatures in urban areas – temperatures in rural areas) is negative rather than the expected positive. They find an average negative trend of 0.342 deg F per hundred years. (Or 0.00342 deg F per year).

I have a couple of concerns about the results they have reported, which requires that I carry out some comparative plotting of my own to generate similar trends. Since I will be looking at the 48 contiguous states (though some will drop out as being too small) this will take a little while. So I ask you to bear with me if posting is a bit sparse while I run these numbers.