Rainfall Retrieval and Flooding Monitoring in China using TRMM Microwave Imager(TMI).

Abstract

The ability of the Tropical Rainfall Measuring Mission Microwave Imager (TRMM/TMI) for rainfall and flooding detection has been demonstrated in this study. A dynamic cluster K-mean method was presented to classify surface types and rain areas.Based on the TMI measurements and surface observations during the Huaihe River Basin Energy and Water Cycle Experiment, the scattering index over land (SIL) was developed and a rain rate (RR) retrieval algorithm of TMI was established, in which the RR is the function of SIL and PCT85 (polarization corrected temperature at 85 GHz). Compared with the rainfall derived from the weather radar and the products of TMI(2A12) and TRMM/PR(2A25), the given surface classification method and the rain rate retrieval algorithm can provide reasonable estimates of rain areas and rain rates.On the basis of TMI measurements, for methods, the classification method, the soil wetness index (SWI) method, the polarization difference index (PDI) method, and the polarization ratio index (PRI) method, were utilized to monitor flooding and study soil wetness in the Yangtze River basin and the Huaihe River basin during summer 1998. Compared with the images provided by L-band Synthetic Aperture Radar (L-SAR) and Radar Satellite (Radarsat) and the figures derived from daily rain gauge data based on the Z-index method, the four methods of flooding detection were proved to be successful, among which the PRI method was best.