The HadAT1 data are global radiosonde gridded temperature anomalies at standard levels (850, 700, 500, 300, 200, 150, 100, 50, and 30hPa) in the troposphere and in the lower stratosphere from 1958 to December 2002. This monthly timeseries are available on a 10 degree longitude by 5 degree latitude basis. This dataset supersedes the HadRT dataset. All values are anomalies relative to the monthly 1966-95 climatology.

In the interests of having MSU-equivalent HadAT timeseries available for immediate comparisons with these satellite-derived data, the Hadley Centre have created a set of MSU equivalent measures under very specific criteria. Although justifiable, many of the decisions they have made are subjective and alternative choices could be made that would appear, at least initially, to be equally plausible. Final MSU equivalent measures for the monthly HadAT2 timeseries are available as well as a number of intermediate products required to produce these from the Temperature on Pressure Levels data. For more information on the real MSU instruments, their measurements and their climate timeseries are available from the University of Alabama in Huntsville and Remote Sensing Systems (external links).

HadAT Uncertainty estimates are only available on seasonal products and up until the end of 2002.

The HadAT2 data are global radiosonde gridded temperature anomalies at standard levels (850, 700, 500, 300, 200, 150, 100, 50, and 30hPa) in the troposphere and in the lower stratosphere from 1958 to December 2012. This monthly timeseries are available on a 10 degree longitude by 5 degree latitude basis. This dataset supersedes the HadRT dataset. All values are anomalies relative to the monthly 1966-95 climatology.

The HadAT0 data are global radiosonde gridded temperature anomalies at standard levels (850, 700, 500, 300, 200, 150, 100, 50, and 30hPa) in the troposphere and in the lower stratosphere from 1958 to December 2002. This monthly timeseries are available on a 10 degree longitude by 5 degree latitude basis. This dataset supersedes the HadRT dataset. All values are anomalies relative to the monthly 1966-95 climatology.