Assimilation of GMS-5 satellite winds using nudging method with MM5

With the aid of Meteorological Information Composite and Processing System （MICAPS）, satellite wind vectors derived from the Geostationary Meteorological Statellite-5 （GMS-5） and retrieved by National Satellite Meteorology Center of China （NSMC） can be obtained. Based on the nudging method built in the fifth-generation Mesoscale Model （MM5） of Pennsylvania State University and National Center for Atmospheric Research, a data preprocessor is developed to convert these satellite wind vectors to those with specified format required in MM5. To examine the data preprocessor and evaluate the impact of satellite winds from GMS-5 on MM5 simulations, a series of numerical experimental forecasts consisting of four typhoon cases in 2002 are designed and implemented. The results show that the preprocessor can process satellite winds smoothly and MM5 model runs successfully with a little extra computational load during ingesting these winds, and that assimilation of satellite winds by MM5 nudging method can obviously improve typhoon track forecast but contributes a little to typhoon intensity forecast. The impact of the satellite winds depends heavily upon whether the typhoon bogussing scheme in MM5 was turned on or not. The data preprocessor developed in this paper not only can treat GMS-5 satellite winds but also has capability with little modification to process derived winds from other geostationary satellites.