Monitoring of Integrated Water Vapour from ground-based GPS observations and their assimilation in a limited-area NWP model

Abstract Detailed short-range numerical weather prediction (NWP) requires observational information of good quality and with high spatial/temporal resolution. Due to various limitations, important quantities such as tropospheric water vapour are often inadequately covered by conventional observations from radiosondes or by meteorological satellite systems. The Global Positioning System (GPS) is developing into a powerful source of humidity information for fine-scale regional models. Since May 2000, the GeoForschungsZentrum in Potsdam has been processing the data from a dense network of German GPS ground stations in near-real time. The final product, Integrated Water Vapour, has been monitored at the Deutscher Wetterdienst, and preliminary assimilation experiments have been carried out to test the impact of the new observations in the operational non-hydrostatic limited-area NWP model.