2015: record hot or not?
Figure 1 Surface thermometer (GISS LOTI and HadCrut4) and satellite (UAH and RSS) records compared. It is plain to see that surface thermometers set a new record in 2015 while the satellites did not.
In this post I am looking at two of the surface thermometer records (GISS LOTI and HadCrut4) and the only two versions of the satellite record (UAH and RSS). The surface thermometer models are based to a large extent on the same surface thermometer data base where air temperature is measured over land and sea surface temperature (SST) is measured over the oceans. The results are area weighted with the SSTs contributing about 70% of the total. The satellite models are based on the exact same satellite recordings. We will see that there is no material difference between GISS LOTI and HadCrut4 and no material difference between UAH and RSS.
The satellite record begins in 1980 and it is only the post-1980 parts of the records that are considered here. The records use different base periods from which temperature anomalies are calculated and this hinders direct comparisons. This is overcome by rebasing each series to 1980-1984 = 0˚C. The online data sources and how to find them are detailed in the appendix.
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