DMI is extracting ZTD's, pressure and 2mT information from the operational NWP model HIRLAM for the locations of the GPS sites delivering data for TOUGH. The data are meant for validation, for studies of error statistics, and for conversion of ZTD's to ZWD or IWV at institutes where that is needed, but where superior information (from observations or a local NWP model) enabling the conversion is not available. The extraction of data and calculation of delays are described in detail in the HIRLAM-model-data-specification document

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