The UAH satellite temperature dataset, developed at the University of Alabama in Huntsville, infers the temperature of various atmospheric layers from satellite measurements of radiance.
It was the first global temperature datasets developed from satellite information and has been used as a tool for research into surface and atmospheric temperature changes. The dataset is published by John Christy et al. and formerly jointly with Roy Spencer.
Satellite temperature measurements
Satellites do not measure temperature directly. They measure radiances in various wavelength bands, from which temperature may be inferred. 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 have obtained different temperature data. Among these groups are Remote Sensing Systems (RSS) and the University of Alabama in Huntsville (UAH). The satellite series is not fully homogeneous – it is constructed from a series of satellites with similar but not identical instrumentation. The sensors deteriorate over time, and corrections are necessary for satellite drift and orbital decay. Particularly large differences between reconstructed temperature series occur at the few times when there is little temporal overlap between successive satellites, making intercalibration difficult.
Description of the data
UAH provide data on three broad levels of the atmosphere.
- The Lower troposphere – TLT (originally called T2LT).
- The mid troposphere – TMT
- The lower stratosphere – TLS
Data are provided as temperature anomalies against the seasonal average over a past basis period, as well as in absolute temperature values.
All the data products can be downloaded from the UAH server.
Data are available as global, hemispheric, zonal, and gridded averages. The global average covers 97-98% of the earth’s surface, excluding only latitudes above +85 degrees, below -85 degrees and, in the cases of TLT and TMT, some areas with land above 1500 m altitude. The hemispheric averages are over the northern and southern hemispheres 0 to +/-85 degrees. The gridded data provide an almost global temperature map.
Daily global, hemispheric and zonal data are available. Monthly averages are available in gridded format as well as by hemisphere and globally.
Each set has data back to December 1978.