贵州南部一次突发性大暴雨的中尺度分析

Mesoscale Analysis of a Heavy Rain in the South of Guizhou

利用地面加密观测资料、贵州自动站雨量资料、FY-2C卫星红外辐射亮度温度(tbb)资料等,对2006年6月12日夜间贵州南部突发性大暴雨过程进行了中尺度分析。结果表明:具有类似于MCC(Mesoscale Convective Complex)特征的中尺度对流云团的发生发展及其缓慢东移是造成此次大暴雨的直接原因。对流层中低层大量的水汽输送和对流有效位能的积累为大暴雨的形成提供了有利的环境条件,中高层弱冷空气入侵使偏南暖湿气流被迫抬升、地面中尺度低压和辐合线的形成是暴雨发生的可能触发机制。中尺度天气系统具有低层辐合、高层辐散的高、低空配置,暴雨区南、北两侧的正、反垂直环流构成了中尺度次级环流圈的垂直结构特征。

A mesoscale analysis for the heavy rain at night on 12 June 2006 in Guizhou Province is performed using the surface intensified observation, rainfall of automatic weather stations, FY-2C satellite tbb, etc. Results indicate that the mesoscale convective cloud clusters and their slowly moving are the direct reason for the heavy rain. Rich water vapour transport and the accumulation of CAPE （Convective Available Potential Energy） in the mid- and low-levels provide the favorable environmental conditions for the occurrence of the heavy rain, which is probably triggered by the lifting of warm and humid airflow forced by the intrusion of weak cold air from high- and mid-levels, and the formation of mesoscale low and mesoscale convergence line. Mesoscale weather systems have the features of convergence in the low level and divergence in the high level and the vertical structure of mesoscale secondary circulations.