Synthetic satellite imagery in the Lokal-Modell

The implementation of a forward radiative transfer model into the code of the Lokal-Modell (LM) of Deutscher Wetterdienst (DWD) allows for the operational computation of synthetic satellite imagery. This new diagnostic tool (LMSynSat, Lokal-Modell Synthetic Satellite imagery) is used to evaluate forecast quality using observed satellite data of Meteosat 7 and Meteosat 8. An obvious model deficiency in simulating high clouds can be overcome by running the LM with new prognostic precipitation and cloud-ice schemes providing more realistic cloud properties. Additionally, the inclusion of precipitating snow crystals in the computation of brightness temperature achieves better agreement of upper tropospheric clouds. Aiming at an objective usage of satellite imagery to select good members out of an ensemble of LM forecasts requires a realistic representation of clouds in the LM.