My previous post noted a substantial change in the adjusted GISTEMP output temperature series for Dublin Airport between data downloaded from GISS on March 12th when compared to data downloaded from GISS on March 6th, while the input data for this station (GHCN v2 adjusted temperature series) showed only much smaller changes.
This may simply reflect the fact that the GHCN v3 data for September to November 2011 was missing in early March download from GISS. If this is the case, it seems undesireable that missing data for a single quarter should have such a pronounced effect on the adjusted output. It could also be the case that this change arises as a result of changes to the GHCN v3 adjusted data for rural stations which GISTEMP uses to adjust Dublin Airport. This is a possibility which will take more time to check, and will be considered in a later extension of this post. For now however I will just present a comparison of the data downloaded on these two dates.
Input data (GHCN v3 adjusted)
The input data changes by no more than 0.1 degrees between March 6th and March 12th
GISTEMP output data (adjusted temperature series)
whereas the output data changes by up to 0.4 degrees.
March 12th v3 adjustment compared to v2 adjustment
which now shows an additional 0.2 degrees temperature rise between 1881 and 2001, and varying changes to the temperature change between other dates and now, when compared to the temperature changes shown in the previous post for data downloaded on March 6th.