Application Of Special Sensor Microwave/imager Data For Analysis Of Cyclonic Storms In Midlatitudes Over The Sea

Abstract

Abstract : Previously we developed algorithms and criteria for identifying fronts in cyclonic weather systems with data on atmospheric water vapor and rain obtained with microwave sensors in space. Using data from the 18, 21 and 37 GHz channels of the Scanning Multichannel Microwave Radiometer (SMMR) on the SEASAT and NIMBUS-7 satellites, we calculated fields of these variables in cyclonic storms. This report is concerned with currently operating microwave radiometer, the Special Sensor Microwave/Imager (SSM/I) on the F8 satellite in the Defense Meteorological Satellite Program (DMSP). This sensor employs three frequencies with similar characteristics as the ones giving atmospheric water data on SMMR, but not at exactly the same frequencies. For this reason we needed to test the algorithms for identifying fronts with data from this new sensor. In addition, the SSM/I has two channels at 85 GHz which are sensitive to scattering caused by large ice particles and graupel in the clouds. We found that an index of this scattering gives a unique view of the deep clouds in frontal zones. We also tested cloud liquid water and wind algorithms developed for SSM/I, and found good qualitative agreement with conventional data. Several cyclones occuring in the fall of 1987 were examined in some detail. It is clear that microwave sensing of these weather systems from space can give the analyst unique and very useful information to better locate fronts, convective regions, and other weather phenomena over the oceans. Keywords: Meteorological fronts; Atmospheric precipitation; Precipitable water.