一次对流性强降水过程的分析及诊断

为了更好地对江苏沿江及苏南地区夏季对流性强降水的预报提供参考和借鉴,利用美国国家环境预报中心资料,对2010年7月22日南京对流性强降水过程的天气形势、水汽输送、对流有效位能和中尺度对流系统作了分析和诊断,给出了该强降水的系统综合示意图。结果表明:500hPa上我国两槽一脊的分布态势及西太副高的西伸造成了弱冷空气和暖湿气流在南京上空的交汇;700hPa和850hPa存在急流和大风核;该强降水发生前,南京及其附近处于对流有效位能高值区,且位势不稳定;造成该强降水的中尺度对流系统是东北西南向强回波带(飑线)以及在该带西南端的中尺度对流复合体。分析表明,南京位于飑线和中尺度对流复合体的结合部是导致该强降水的直接原因。

Analysis and diagnosis of convectional rainstorm

In order to provide reference resources for prediction of convectional rainstorm in the area along the Yangtze River in Jiangsu and the south of it, reanalysis data, radar echo and satellite cloud imagery of National Centers for Environmental Prediction(NCEP) were used to analyze the synoptic systems, transportation of water, CAPE and mesoscale convective system of a convectional rainstorm occurred in Nanjing on July 22, 2010. The comprehensive diagram of the systems of the convectional rainstrom was also given in this paper.The major results are as follows: (1) Two ridges and a trough at 500 hPa and the westward subtropical high lead to the convergence of the weak cold air and warm-wet flow in Nanjing. (2) There are jet and strong wind cores at 700 hPa and 850 hPa. (3) Nanjing and its vicinity have potential instability and high values of convective available potential energy before the rainstorm. (4) The mesoscale convective system in this rainstorm process is the returning band (squall line) from northeast to southwest, and there is MCC in the southwestern termination of it. Nanjing is in the connecting areas of them. This is the immediate cause of the rainstorm.