A Study On The Application Of AMVs Derived By The Second Order Method In Cloud-free Region From Geostationary Satellite In Forcast Of Typhoon

For the excellent temporal and spatial resolution, Atmospheric motion vectors(AMVs) display an important role in typhoon analysising and numerical forecasting. AM Vs in cloud-free regions around typhoon have been retrieved by The Second Order methhod, the work is mainly carry out from the quality control, Cases studies and wind vector error's quantitative comparison, the application of the AMVs in cloud-free regions in typhoon track forecasting :Firstly,The quality control is generally based on vector checks and simple threshold techniques to eliminate unreasonable vectors. All vectors compared with ERA wind field that show a directional deviation or discrepancy larger than a predefined value are rejected in this study.Case studies are presented in this part. In case studies, we derived the cAMVs around typhoon with the SD method. And the BIAS, MVD, SD and RMSE of AMVs which before and after QC are also calculated as compared with NCEP 800 hPa wind fields. The results show that the cAMVs after quality control can effectively reduce the error of wind speed andwind direction; SD and RMSE of cAMVs also can be reduced from an average of 7.8 m/s and 19.7 m/s to the anvage of 2.0 m/s and 4.6 m/s.In the experiment of forecasting typhoon HAIKUI? Chan-hom and Muifa, the quality of AMVs in cloud-free regions directly affect the numerical prediction effect.The assimilation algorithm can adjust the physical structure of the background field ,such as geopotential height ? winds and humidity. Compared with the control test, assimilating AMVs in cloud-free regions can clear improve the typhoon' s track and precipitation forecast.