Simulation of Raindrop Size Distribution:Verification using the Dual-polarization Radar

• Main Authors: Wei-ren Tseng, 曾威仁
• Other Authors: 陳台琦
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/86088359450160761331

碩士 === 國立中央大學 === 大氣物理研究所 === 95 === Along the long history of the microphysical model development, the distrometer is one of the main tools to verify the evolution of the raindrop size distribution from the model calculation. In this research, the advantages of the dual-polarization radar, such as, the greater spatial and temporal resolution, and the ability of retrieving the raindrop size distribution using the reflectivity (ZH) , differential reflectivity (ZDR), and a given μ - Λ relationship in the gamma form distribution. So, the major purpose of this research is to use radar data to confirm the output of the one dimensional cloud model during the real case. In order to understand the characteristics in both the stratiform and convective zones of a summer thunderstorm in North Taiwan, the raindrop size distribution in both regions were carefully retrieved from the dual-polarization radar data. There are distinct results in the stratiform and convective zones. In the stratiform zone, the median volume diameter (D0) retrieved from the NCU radar is increasing downward. Although lacking the advection information in the model, the outputs agree well with the observation data. In the convective zone, the median volume diameter computed from the model is decreasing at first 1 km decent and then near constant along the rest of the fall. The radar retrieval were also near constant below 3.5 km however. The possible explanations are the existence of ice or supercooled water in the convective area; it causes the error in both radar retrieval and model calculations because of the default warm rain assumption.