Tuesday, 7 August 2007
Halls C & D (Cairns Convention Center)
Hydrometeor type classification in precipitation clouds is useful for not only study of precipitation mechanisms but also disaster prevention and improvement of weather forecast. In order to develop hydrometeor classification method using X-band polarimetric radar measurements, simultaneous observations were carried out by the NIED X-band polarimetric radar (MP-X) and the hydrometeor videosondes (HYVIS) in Niigata prefecture, Japan for about three weeks in December 2001. Characteristics of polarimetric measurements of reflectivity at horizontal polarization, differential reflectivity and correlation coefficient and temperature for six hydrometeor types, that is, rain, drizzle, sleet, graupel, aggregate and ice crystal, were derived from comparisons of MP-X and HYVIS data.
Results of hydrometeor classification using fuzzy logic technique including a hybrid rule strength and its verification are also presented. The beta membership functions were specified based on the derived characteristics of polarimetric measurements for each hydrometeor type. To extend the application of the method to summer precipitation clouds, characteristics of polarimetric measurements for rain, melting layer and hail collected in summer season by MP-X radar will be incorporated.
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