摘要
On August 5, 2001, Shanghai was struck by a torrential rainfall due to thepassage of a tropical depression (TD). The rainfall intensity has been the strongest in recent 50years. In this paper, a set of mesoscale re-analyses data and the planetary boundary layerobservation 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 explosivedevelopment of cyclonically vertical vorticity in the region with steep potential temperaturesurfaces in front of the TD; while the cyclonic vorticity increased notably at higher levels due tpthe small atmospheric vertical stability of westerly currents in the vicinity of Shanghai. Thesimultaneous sharp development of cyclonic vorticity at different levels should be the main causefor the torrential rainfall.
On August 5, 2001, Shanghai was struck by a torrential rainfall due to thepassage of a tropical depression (TD). The rainfall intensity has been the strongest in recent 50years. In this paper, a set of mesoscale re-analyses data and the planetary boundary layerobservation 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 explosivedevelopment of cyclonically vertical vorticity in the region with steep potential temperaturesurfaces in front of the TD; while the cyclonic vorticity increased notably at higher levels due tpthe small atmospheric vertical stability of westerly currents in the vicinity of Shanghai. Thesimultaneous sharp development of cyclonic vorticity at different levels should be the main causefor the torrential rainfall.
基金
This study is sponsored by the National Natural Science Foundation of China under Grant Nos. 49975014 and 40275018.
