Fresno Airport is one of the sites in the Parker 2006 network that is used to argue that there is a negligible UHI component in temperature increases in the major indexes. Here is a picture of this rustic location (which is still on the surfacestations.org to do list):
Parker has a figure showing results for Fresno. I’ve collated all the relevant daily NCEP and temperature data for Fresno online here and tried to replicate this figure without success.
First here is a plot of GSN daily data (summarized to annual averages) categorized for windy max, windy min, calm max, calm min and mean. To calculate this, I downloaded all the NCEP daily uwind and vwind 10-m wind data from 1948 to 2006 (over 1 GB of data) and extracted the data for the Fresno gridcell. Nicholas gave me some help on handling the downloading – he is really good at it. In this particular case, there is a difference between calm tmax and windy tmax, but not really for tmin. The long-term increase is primarily in the tmin.
GSN is only version of Fresno airport data. The next graphic shows the GSN version as well as USHCN, GHCN and GISS versions. In this case, the GSN version used by Parker is equivalent to the USHCN TOBS version (before their station history adjustments), which, in this case, is virtually equal to the USHCN raw version. The adjusted GISS version is higher than the Parker GSN version.
The next graphic shows differences between several key versions of Fresno airport. In this case, the third row shows the difference between the GISS adjusted version and Parker’s version. Even Hansen does an adjustment of up to 1 deg C for this data.
Parker shows the following figure for Fresno from which he concludes that there is a discontinuity in the mid-1970s.
Far be it from me to suggest that one of these data sets lacks discontinuities, but I wasn’t able to replicate this diagram. My replication is as below. Now it’s quite possible that I’ve implemented some step in Parker’s loosely described methodology differently; I asked Parker to give me exact URLs for his data, which he didn’t do. It’s possible that I’ve downloaded a different edition. I’m pretty sure that I’ve at least done a plausible interpretation of his methodology and got a different looking figure.
I don’t plan to wade through Parker’s data site by site. I picked this site because it was close to the sites that Anthony Watts was working on and for no other reason.