Added Value of 3D Winds Derived from Geostationary Hyperspectral IR Sounder on Tropical Cyclone Forecasts

A geostationary (GEO) hyperspectral infrared (IR) sounder (GeoHIS) not only provides radiance measurements containing thermodynamic information, but also enable deriving the three-dimensional (3D) horizontal winds when high temporal information is used. The Geosynchronous Interferometric Infrared Sounders (GIIRS) onboard Fengyun-4A and FengYun-4B can provide targeted observations with 15-minute to 30-minute temporal resolution, enable 3D winds with high temporal resolution. To understand the impact of such new atmospheric 3D wind information on predicting high impact weather (HIW) events such as tropical cyclones (TCs), it is important to address the two questions:(1) what is the added value of GeoHIS 3D winds on predicting TCs when the advanced geostationary imager observations are used? (2) what is the added value of GeoHIS 3D winds on predicting TCs when the thermodynamic information from the same instrument is also used? Using both research and operational numerical weather predict (NWP) regional models (WRF and CMA-MESO) and GIIRS 3D wind data, impact studies have been conducted with variational data assimilation systems, results indicatethe added value of GeoHIS3D winds on TC forecasts. The track, intensity and precipitation forecasts are substantially improved through better presenting dynamic initial fieldin the NWP models when GeoHIS 3D winds are assimilated, and dynamic information provides better sensitivity than the thermodynamic information on TC forecasts in our regional NWP impact studies.

Keywords: 3D tropospheric winds, geostationary hyperspectral infrared sounder, data assimilation, numerical weather prediction, tropical cyclone.