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Assimilation of HIRS/3 Brightness Temperature in Cloud Condition and Its Impact to CHANCHU Typhoon
Weiyu Ding, Guangzhou Institute of Tropical and Marine Meteorology, Guangzhou, China
Satellite radiation data assimilation will be easily influenced by clouds , huge of satellite data can not be assimilated to numeric model in cloudy cases. One reason is that initial clouds structure can not be easily obtained, which are preferred for an observation operator in variational system. Because of the high cloud fractions in the tropics and the close links between clouds and extreme synoptic processes, such as typhoons and heavy rains, high-accuracy three-dimensional cloud structures are needed for the attempt to assimilate satellite radiation data, especially infrared channels. Based on the GRAPES-3DVAR(Global and Regional Assimilation and Prediction Enhanced System)and the simulated cloud structures of CHANCHU typhoon by WRF(Weather Research and Forecasting Model), which are added to the RTTOV(fast radiative transfer model for TOVS)as input variables, the infrared channels brightness temperature are assimilated into the numeric model and its impact to typhoon forecast are analyzed. Results show that while providing the initial cloud structures , some of NOAA-16(National Oceanic and Atmospheric Administration) HIRS/3(High Resolution Infrared Radiation Sounder) channels, such as channels 4-8,10 and 13-19, can be assimilated properly, the temperature and moisture structure of typhoon can be improved, the HIRS/3 infrared channels assimilation have positive impact on short-term precipitation forecast. Key words: Typhoon CHANCHU, HIRS/3 infrared channel, assimilation
Poster Session 1, IOAS Poster Session I: Data Assimilation and Impact Studies
Monday, 21 January 2008, 2:30 PM-4:00 PM, Exhibit Hall B
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