A flooding index and its regional threshold value for monitoring floods in China from SSM/I data

Abstract

Flooding is always closely related to the regional geographical conditions. The globally optimized algorithms of data validation for the DMSP SSM/I, such as a rule TB22v-TB19v > 4K, are not applicable to monitoring flood without specific knowledge of regional geography. This Letter investigates the SSM/I data during the rain and flood time of June-July 1996 in southern China, and proposes a flooding index FI = TB37h - TB85h and its regional threshold value F0 for monitoring flooding. Flooding is considered to occur when FI < F0. In two examples selected from the watery Wuhan and mountainous Wuyuan regions, temporal and spatial variation of the flooding index FI and another two indices, the scattering index SI and surface polarization index PI, are discussed. Numerical simulation of radiative transfer modelling for these indices is also presented.