Satellite temperature measurements

Satellite temperature measurements have been obtained for troposphere since 1978. By comparison, the usable balloon (radiosonde) record begins in 1958.

Satellites do not measure "temperature" as such. They measure radiances in various wavelength bands, which must then be mathematically inverted to obtain indirect inferences of temperature. The resulting temperature profiles depend on details of the methods that are used to obtain temperatures from radiances. As a result, different groups that have analyzed the satellite data to calculate temperature trends have obtained a range of values. Among these groups are Remote Sensing Systems (RSS) and the University of Alabama in Huntsville (UAH).

Climate models predict that as the surface warms, so should the global troposphere. Globally, the troposphere should warm about 1.2 times more than the surface; in the tropics, the troposphere should warm about 1.5 times more than the surface. For some time the only available satellite record was the UAH version, which showed cooling globally. A longer data series and several corrections to the UAH method leaves the UAH series showing warming, though less than RSS version. In 2001, an extensive, but now somewhat dated, comparison and discussion of trends from different data sources and periods was given in the Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) (section 2.2.4).