The HADRT data are global radiosonde gridded temperature anomalies at standard levels in the troposphere and in the lower stratosphere from 1958 to July 2004. The data are degree Celsius anomalies from 1970-1990 means. Anomalies are calculated for each of about 200 sonde stations worldwide and grid values derived from these. Several versions of the HadRT data are available. The recommended HadRT product for most purposes is HadRT2.1s. This dataset has been superseded by the HadAT dataset collection, also available from CEDA. These pages are provided for the benefit of existing and past users of HadRT. New and existing users are now encouraged to use the HadAT dataset collection instead.

The HadAT 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 gridded product is derived from 676 individual radiosonde stations with long-term records. Because of the criteria of data longevity the resulting dataset is limited to land areas and primarily Northern Hemisphere locations. Radiosondes are single launch instruments and there have been many changes in instruments and observing practices with time. HadAT has used a neighbour-based approach to attempt to adjust for these effects and produce a homogeneous product suitable for climate applications. Zonal averages were created by averaging all available gridbox values in each 5 degree latitude band. Large scale mean timeseries for the globe and the tropics (defined here as 20N to 20S) are simply cos(lat) weighted zonal mean field values. This reduces the spatial sampling bias towards Northern Hemisphere mid-latitudes. Other plausible large-scale averaging techniques would impact the timeseries values calculated. Cautionary note from the Met Office Hadley Centre It is important to note that significant uncertainty exists in radiosonde datasets reflecting the large number of choices available to researchers in their construction and the many heterogeneities in the data. To this end we strongly recommend that users consider, in addition to HadAT, the use of one or more of the following products to ensure their research results are robust. Currently, other radiosonde products of climate quality available from other centres for bona fide research purposes are: - Radiosonde Atmospheric Temperature Products for Assessing Climate (RATPAC) - RAdiosonde OBservation COrrection using REanalyses and Radiosonde Innovation Composite Homogenization ) - IUK (Iterative Universal Kriging) Radiosonde Analysis Project Also see a comparison with Microwave Sounding Unit (MSU) data by Remote Sensing Systems (see links under Docs tab below) .

The HADRT2.2u data are global monthly fields of radiosonde temperature anomalies at standard pressure levels on a 10 degree latitude by 20 degree longitude grid from 1958 to 2000. Anomalies are calculated with respect to 1971-1990 climatology. Anomalies are available for 9 standard levels (850, 700, 500, 300, 200, 150, 100, 50, 30hPa) as well as tropospheric (850 - 300hPa) and stratospheric (150 - 30hPa) averages. The data are degree Celsius anomalies from 1970-1990 means. Anomalies are calculated for each of about 200 sonde stations worldwide and grid values derived from these. HADRT2.2u are as HADRT2.2 but created from HADRT2.0. This dataset has been superseded by the HadAT dataset also available from CEDA.

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.

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.

The HADRT2.3 data are global monthly fields of radiosonde temperature anomalies at standard pressure levels on a 5 degree latitude by 10 degree longitude grid from 1958 to 2000. Anomalies are calculated with respect to 1971-1990 climatology. Anomalies are available for 9 standard levels (850, 700, 500, 300, 200, 150, 100, 50, 30hPa) as well as tropospheric (850 - 300hPa) and stratospheric (150 - 30hPa) averages. The data are degree Celsius anomalies from 1970-1990 means. Anomalies are calculated for each of about 200 sonde stations worldwide and grid values derived from these. HADRT2.3 is a globally complete dataset based on HadRT2.1 1958-2000, but with gaps filled in by reference to the second derivative of the corresponding NCEP reanalysis temperature fields, using the Laplacian technique of Reynolds, 1988: A Real-Time Global Sea Surface Temperature Analysis. J. Climate (see docs for a link to this publication) This dataset has been superseded by the HadAT dataset also available from CEDA.

The HADRT2.2 data are global monthly fields of radiosonde temperature anomalies at standard pressure levels on a 10 degree latitude by 20 degree longitude grid from 1958 to 2000. Anomalies are calculated with respect to 1971-1990 climatology. Anomalies are available for 9 standard levels (850, 700, 500, 300, 200, 150, 100, 50, 30hPa) as well as tropospheric (850 - 300hPa) and stratospheric (150 - 30hPa) averages. The data are degree Celsius anomalies from 1970-1990 means. Anomalies are calculated for each of about 200 sonde stations worldwide and grid values derived from these. HADRT2.2 is an eigenvector reconstructed grid data set from 1958 - 2000, on a 10 degree latitude by 20 degree longitude grid, created from HadRT2.1. The eigenvector reconstruction was used to infill missing seasons or years in boxes with 70% of seasonal or annual data available. This dataset has been superseded by the HadAT dataset also available from CEDA.

The HADRT2.1 data are global monthly fields of radiosonde temperature anomalies at standard pressure levels on a 5 degree latitude by 10 degree longitude grid from 1958 to July 2004. Anomalies are calculated with respect to 1971-1990 climatology. Anomalies are available for 9 standard levels (850, 700, 500, 300, 200, 150, 100, 50, 30hPa) as well as tropospheric (850 - 300hPa) and stratospheric (150 - 30hPa) averages. The data are degree Celsius anomalies from 1970-1990 means. Anomalies are calculated for each of about 200 sonde stations worldwide and grid values derived from these. HADRT2.1 is as HadRT2.0 but with bias corrections made to many station time series world-wide. The adjustments were calculated by reference to MSU data products, but only for known changes in instrumental or operational procedures for the period post 1979. No data are available for the 30hPa level in this version. This dataset has been superseded by the HadAT dataset also available from CEDA.

The HADRT2.1s data are global monthly fields of radiosonde temperature anomalies at standard pressure levels on a 5 degree latitude by 10 degree longitude grid from 1958 to July 2004. Anomalies are calculated with respect to 1971-1990 climatology. Anomalies are available for 9 standard levels (850, 700, 500, 300, 200, 150, 100, 50, 30hPa) as well as tropospheric (850 - 300hPa) and stratospheric (150 - 30hPa) averages. The data are degree Celsius anomalies from 1970-1990 means. Anomalies are calculated for each of about 200 sonde stations worldwide and grid values derived from these. HADRT2.1s is a combination of HadRT2.0 in the troposphere (up to and including 200hPa) and HadRT2.1 in the stratosphere (above 200hPa). This dataset has been superseded by the HadAT dataset also available from CEDA.

The HADRT2.3s data are global monthly fields of radiosonde temperature anomalies at standard pressure levels on a 5 degree latitude by 10 degree longitude grid from 1958 to 2000. Anomalies are calculated with respect to 1971-1990 climatology. Anomalies are available for 9 standard levels (850, 700, 500, 300, 200, 150, 100, 50, 30hPa) as well as tropospheric (850 - 300hPa) and stratospheric (150 - 30hPa) averages. The data are degree Celsius anomalies from 1970-1990 means. Anomalies are calculated for each of about 200 sonde stations worldwide and grid values derived from these. HADRT2.3s is as HadRT2.3 but using HadRT2.1s. This dataset has been superseded by the HadAT dataset also available from CEDA.