| Summary: | 碩士 === 國立中央大學 === 大氣物理研究所 === 94 === Measurements of the drop size distribution(DSD) have a broad range of applications in meteorology and hydrology.
The characteristics of an averaged DSD,which represents a precipitation type in a climatological region,are important for cloud-modeling studies.
The observations were designed to test how accurately they measure drop size distribution by Impact(JWD) and Optical(2DVD) disdrometers.The comparison of DSDs,raindrop in 1.5〜2.5mm showed good agreement between two types of disdrometers.
The Joss-Waldvogel disdrometer underestimate small drop size in weak rainfall rate, and underestimate small and big drop size in strong rainfall rate.Beside,the Gamma parameter distribution also showed good agreement between two types of disdrometers.
Further more, apply A long-period and copious data observed by Optical disdrometer(2DVD) to analyze the precipitation characteristics during different season and different precipitation type. In different season analysis, D0 value in each season varies with rainrate, and the distribution of D0 value from large to small is winter，spring，typhoon， fall ，meiyu season.
In analysis of different precipitation type, the D0 value of the fronal type and typhoonic type is apparent small than the local precipipation type when R>20mm/hr.It might result from the drop broken easily and evolved hardly when it is in strong rainrate affected by the frontal system or typhoon. Local precipipation type usually have big drop size distribution.
In the same precipipation type analysis of different season，we found：(1)The local precipipation type: the DSD in winter is similar with spring. The DSD in meiyu season is similar with typhoon season. The DSD in fall is between winter and meiyu season. (2)The DSD of front precipipation type is seasonal dependent. The distribution of D0 value from large to small is : winter〜spring>meiyu>fall(3)The DSD of typhoon precipipation seems seasonal independent.
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