Microwave Derived Rainrates in Typhoons and Their Use in the Diagnosis and Prediction of Typhoon Intensity
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
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An algorithm to convert satellite measured microwave radiances to rainfall rates was used to analyze the rainfall patterns of western North Pacific Ocean typhoons. These rainfall rates and patterns were correlated to the typhoons Dvorak intensities both present and future in search of diagnostic insights and prognostic aids. The number of local maxima of mean annular rainfall rates correlated strongly with the filling or deepening of a typhoon. Storms with multiple peaks filled, indicating the existence of the barrier effect. An effective radius which demarks two regions where latent heat release either raises or depresses the central pressure was postulated. Cross-sections of convective and stratiform rainfall indicated both the importance of stratiform rain and the need for an active convective core in growing typhoons. The ratio of convective to total precipitation also showed the importance of stratiform rain to storm intensification and illustrated the barrier effect. Finally, northwesterly moving typhoons were examined in detail. Stable regression estimates of storm intensification were found.