The Characteristic of Drop Size Distribution During SoWMEX

• Main Authors: Yi-ru Chen, 陳奕如
• Other Authors: Pay-liam Lin
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/02073854756182171013

碩士 === 國立中央大學 === 大氣物理研究所 === 97 === In 2008,a joint field experiment named SoWMEX/TiMREX was conducted in southern Taiwan.Most previous studies of the DSD in Taiwan focus on the north, and therefore this experiment is expected to help analyze the DSD in the south. Six disdrometers located in Quan-Xin,Ma-Ja,Quan-Fu,Fan-Hua,and Chin-San were utilized. This study analyzes precipitation events from May 16 to June 30 and discusses the properties of the DSD for different precipitation types. No matter what distinguishing precipitation types method used,the result shows the drop number concentration of convective precipitation is an order of magnitude larger than that of stratiform rain, and the range of the convective DSD is larger as well. When these two types are distinguished with 20 mm/hr as a rain rate boundary, the drop number concentration of convective rainfall is more than that of stratiform rain for drop sizes more than 2.0 mm, and less for drop sizes smaller than 2.0 mm. In addition, the rainfall and D_m observed in Chin-San are larger than the others because of its higher altitude. Compared with the Dm-Nw relation deduced by Bringi et al.(2003),there are similar results with the stratiform rainfall in southern Taiwan, while the convective rain is maritime-like and close to that observed in northern Taiwan. The rainfall properties of the Mei-yu season in 2008 is analyzed using an 2DVD located in Quan-Xin. The total rainfall duration is 8383 minutes, within which the stratiform rain is 5523 minutes(65%) and the convective rain is 2500 minutes(34%).The total rainfall accumulation is 987 mm, within which the stratiform one is 190.11mm(19%) and the convective one is 794.14 mm(80%). Therefore it’s shown that, in the Mei-yu season, the statiform rain is the major contribution to the rainfall duration while the short-time convective rainfall contributed to the most accumulation rainfall . DSD parameter statistics shows, slope parameterΛ, mean mass diameter Dm, liquid water content LWC and reflectivity dBZ are all larger in the convective rain than in the stratiform one, but the event frequency and shape parameter μ of the stratiform rainfall is larger instead.But the results derived from N0-R relation method has converse with the others while in convective type.