DIAGNOSIS OF TYPHOON SPIRAL CLOUD BAND AT SEA WITH SSM/I IMAGE

This paper describes the characteristics of the Special Sensor Microwave/Imager (SSM/I) onboard the Defense Meteorological Satellite Program (DMSP),analyzes absorbing,re-emitting and scattering effects of the atmospheric particles (especially cloud particles and rain drops).The inner physical cause of typhoon's representative form on microwave images is revealed.An index of particle size is then induced as such:Symmetrically inverse channel 85H's (85H is an abbreviation for channel 85.5 GHz in horizontal polarization,see Table 1 in the text.) absorption segment and put it into the extension of the scattering segment.The precipitation index was formed as the average of three elements:normalized 19H,normalized 37H,and inversed normalized 85H.It is approved that the image of particle size index overcomes some shortcomings of the single raw channel,such as:37H is not sensitive to large rain drops,85H is not sensitive to mid-size rain drops and can reveal typhoon's spiral structure more clearly.