Michael Bender, Deutscher Wetterdienst (DWD)

GPS Slant Delay Assimilation for Convective Scale NWP

Klaus Stephan, Christoph Schraff, Hendrik Reich, Andreas Rhodin, Roland Potthast


Atmospheric delays of GPS signals provide information about the structure of the atmosphere, especially the water vapor distribution. A slant total delay (STD) assimilation operator was developed at the German Weather Service (DWD) to assimilate STD and ZTD (zenith total delay) observations into the numerical weather models. A pre-operational version of the ensemble Kalman filter for convective scale data assimilation (KENDA) was used to run the COSMO-DE local model together with the STD assimilation operator. Hourly COSMO-DE forecasts of 40 ensemble members were processed by the local ensemble transform Kalman filter (LETKF) to obtain the analyses and 24-hour forecasts were started every 6 hours. First STD assimilation experiments show a positive impact and some initial results will be presented.

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