Improve tropical cyclone forecasts with hyperspectral infrared sounder data

The High spectral resolution infrared sounders such as AIRS, IASI and CrIS provide atmospheric temperature and moisture profiles with high vertical resolution and good accuracy. Those advanced IR sounders provide soundings in hurricane environment, which is critical for tropical cyclone forecasts. In order to demonstrate the application of advanced IR sounder data in tropical cyclone forecasts, both the AIRS radiances and the atmospheric temperature and moisture retrievals in clear skies are used in regional numerical weather prediction (NWP) model. The advanced Research WRF (ARW) modeling system is used as NWP model in our studies, and the Community Gridpoint Statistical Interpolation (GSI) system is used as data assimilation system. To analyze the impact of AIRS radiances and sounding retreivals on TC forecasts, Hurricane Irene (2011) case is used in the experiments, every 6 hours the observational data are assimilated followed by the 48 hour forecasts. The assimilation experiments include conventional data only, conventional data plus advanced IR sounder data, and conventional, advanced IR sounder and microwave sounder (AMSU) data altogether. Hurricane track, sea-level pressure (SLP) and maximum wind speed observations are used to verify the impact of assimilation. Results show that the AIRS retrieved temperature and moisture soundings in clear skies have positive impacts on hurricane Irene forecasts. The impact becomes less for the longer forecasts. The comparison between assimilating radiances and assimilating sounding retrievals will also be presented.