The formation process and cloud physical characteristics for a typical downburstproducing thunderstorm in Beijing  

作　　者：GUO Xueliang FU Danhong Institute of Almospherie Physics, Chinese Academy of Sciences, Beijing 100029. China 

出　　处：《Chinese Science Bulletin》2003年第S2期77-82,共6页

摘　　要：The formation process and characteristics ofcloud physical structure of a severe thunderstorm accompa-nied with strong wind on 23 August, 2001 in Beijing wasstudied using PSU/NCAR mesoscale model ( MM5) couplingwith a severe storm model with hail-bin microphysics. Theresults show that the specific topography and distributionfeatures of cold/warm current in the Beijing region playedprominent roles in forming, developing and maintaining thesevere storm. Due to solar radiation heating and topographiclifting, the convective cells were easily formed when thewesterly airflow passed over high mountainous regions inBeijing. The warm and wet air entered the cloud from itsfrontage and enhanced the convection, and formed a largeamount of graupel/hail particles at the middle and upperportion of the clouds. The precipitation was primarilyformed due to melting of graupel/hail particles. The strongdowndraft was mainly produced by negative buoyancy dueto loading, melting of graupel/hail particles as well asevaporative cooling of rain water. The divergent airflow in-duced by the strong downdraft led to the disastrous burstwinds at the surface and also forced lifting of warm and wetairflow in the moving direction of the storm and formed newclouds that further promoted and maintained the storm de-velopment.The formation process and characteristics of cloud physical structure of a severe thunderstorm accompa- nied with strong wind on 23 August, 2001 in Beijing was studied using PSU/NCAR mesoscale model ( MM5) coupling with a severe storm model with hail-bin microphysics. The results show that the specific topography and distribution features of cold/warm current in the Beijing region played prominent roles in forming, developing and maintaining the severe storm. Due to solar radiation heating and topographic lifting, the convective cells were easily formed when the westerly airflow passed over high mountainous regions in Beijing. The warm and wet air entered the cloud from its frontage and enhanced the convection, and formed a large amount of graupel/hail particles at the middle and upper portion of the clouds. The precipitation was primarily formed due to melting of graupel/hail particles. The strong downdraft was mainly produced by negative buoyancy due to loading, melting of graupel/hail particles as well as evaporative cooling of rain water. The divergent airflow in- duced by the strong downdraft led to the disastrous burst winds at the surface and also forced lifting of warm and wet airflow in the moving direction of the storm and formed new clouds that further promoted and maintained the storm de- velopment.

关 键 词：BEIJING region THUNDERSTORM and disastrous WIND cluud PHYSICAL features. 

分 类 号：P426.5[天文地球—大气科学及气象学]