Rainfall retrieval and flooding monitoring in China using TRMM Microwave Imager (TMI)

The ability of the Tropical Rainfall Measuring Mission Microwave Imager (TR MM/TMI) for rainfall and flooding detection has been demonstrated in this s tudy. A dynamic cluster K-mean method was presented to classify surface typ es and rain areas. Based on the TMI measurements and surface observations during the Huaihe Ri ver Basin Energy and Water Cycle Experiment, the scattering index over land (SIL) was developed and a rain rate (RR) retrieval algorithm of TMI was es tablished, in which the RR is the function of SIL and PCT85 (polarization c orrected temperature at 85 GHz). Compared with the rainfall derived from th e weather radar and the products of TMI(2A12) and TRMM/PR(2A25), the given surface classification method and the rain rate retrieval algorithm can pro vide reasonable estimates of rain areas and rain rates. On the basis of TMI measurements, four 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 m onitor flooding and study soil wetness in the Yangtze River basin and the H uaihe 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.