Role of a Meso-γ Vortex in Meiyu Torrential Rainfall over the Hangzhou Bay,China:An Observational Study  

作　　者：翟国庆 张红蕾 沈杭锋 朱佩君 苏涛 李小凡 

机构地区：[1]School of Earth Sciences,Zhejiang University [2]Hangzhou Weather Bureau

出　　处：《Journal of Meteorological Research》2015年第6期966-980,共15页气象学报（英文版）

基　　金：Supported by the National Natural Science Foundation of China(41175047 and 41475039);National(Key)Basic Research and Development(973)Program of China(2013CB430104 and 2015CB953601)

摘　　要：A mesoscale torrential rainfall event that occurred over eastern China in June 2013 is analyzed by using observational data.The results show that a mesoscale convergence line and a weak convective cloud line formed over the northern part of the Hangzhou Bay during the onset of the torrential rainfall event.A meso-vortex appeared over the confluence point of northeasterly flow associated with the Yellow-Sea high,easterly flow from rainfall area,and southeasterly flow from the Hangzhou Bay.The meso-vortex with a horizontal scale of 10-20 km lasted for about 1 h for stable surface circulations.The analysis of radar retrieval reveals that the meso-vortex in the boundary layer occurred at the south of strong radar echo.The formation of the meso-vortex turned to enhance convergence and cyclonic vorticity in the lower troposphere,which strengthened updrafts that are tilted into convective clouds and caused torrential rainfall.Thus,the occurrence of the meso-vortex in boundary layer is one of the mechanisms that are responsible for the enhancement of convective development.A mesoscale torrential rainfall event that occurred over eastern China in June 2013 is analyzed by using observational data.The results show that a mesoscale convergence line and a weak convective cloud line formed over the northern part of the Hangzhou Bay during the onset of the torrential rainfall event.A meso-vortex appeared over the confluence point of northeasterly flow associated with the Yellow-Sea high,easterly flow from rainfall area,and southeasterly flow from the Hangzhou Bay.The meso-vortex with a horizontal scale of 10-20 km lasted for about 1 h for stable surface circulations.The analysis of radar retrieval reveals that the meso-vortex in the boundary layer occurred at the south of strong radar echo.The formation of the meso-vortex turned to enhance convergence and cyclonic vorticity in the lower troposphere,which strengthened updrafts that are tilted into convective clouds and caused torrential rainfall.Thus,the occurrence of the meso-vortex in boundary layer is one of the mechanisms that are responsible for the enhancement of convective development.

关 键 词：torrential rainfall triggering mechanism mesoscale analysis mesoscale disturbance vortex lower tropospheric convergence line 

分 类 号：P458.121.1[天文地球—大气科学及气象学]