Mesoscale Diagnosis of a Torrential Rainfall Caused by a Tropical Depression

On August 5, 2001, Shanghai was struck by a torrential rainfall due to the passage of a tropical depression (TD). The rainfall intensity has been the strongest in recent 50 years. In this paper, a set of mesoscale reanalyses data and the planetary boundary layer observation from a wind profiler are used to understand the possible mechanism of such a heavy rain. Results show that the outburst of a southerly jet in the lower atmosphere triggered the explosive development of cyclonically vertical vorticity in the region with steep potential temperature surfaces in front of the TD; while the cyclonic vorticity increased notably at higher levels due to the small atmospheric vertical stability of westerly currents in the vicinity of Shanghai. The simultaneous sharp development of cyclonic vorticity at different levels should be the main cause for the torrential rainfall.

作 者： YU Hui LIANG Xudong DUAN Yihong QI Liangbo   作者單位： YU Hui(Nanjing University of Information Science and Technology, Nanjing 210044;Shanghai Typhoon Institute, Shanghai 200030)

LIANG Xudong,DUAN Yihong(Shanghai Typhoon Institute, Shanghai 200030)

QI Liangbo(Shanghai Meteorological Center, Shanghai 200030) 

刊 名： 氣象學報（英文版）  SCI 英文刊名： ACTA METEOROLOGICA SINICA  年，卷(期)： 2005 19(2)  分類號： P4  關鍵詞： tropical depression   torrential rainfall   moist potential vorticity