广西和贵州MCC暴雨过程综合分析

Comprehensive Analyses on Rainstorm Caused by MCC in Guangxi and Guizhou

利用卫星云图、多普勒雷达资料和高空风等各种天气学资料,对2007年6月8～9日广西、贵州由中尺度对流复合体(MCC)引发的致洪暴雨过程进行了大尺度环境场和物理量的诊断分析。结果表明:MCC是造成暴雨的直接影响系统;低空急流的不连续后退向西发展,为MCC的生成和发展提供了充沛的水汽输送;MCC发生区对流层中低层随高度向西倾斜高能管的形成,维持了MCC发生区大气的对流不稳定性;华北高压底部东北气流带来的冷空气沿青藏高原东侧南下产生的锋生,有利于MCC的形成;对于MCC的生成发展、维持和消亡,在CAPPI(1.5 km)径向速度图上看到:首先有西南低空急流生成,接着在西南低空急流左侧出现气旋性辐合或经向辐合;和类似飑线的强对流云带的东移转向南压配合,生成范围很大的径向强辐散区;低空急流的减弱消失,预示着MCC的减弱或消散。

Using the synoptic data such as satellite image, Doppler radar and upper wind, the flooding rainstorm in Guangxi and Guizhou on June 8-9, 2007 caused by MCC is analyzed. The main conclusions are as follows： MCC is the direct influence system to rainstorm; the disconnected recession to western of low-level jet provides enough transmission of vapor to generate and develop MCC. The middle and lower of troposphere inclining to western with height forms the high-energy pipe, which maintains the convective instability in generation area of MCC. Cold air brought by northeast air on bottom of North China High moving southward along east of Tibetan Plateau generates frontogenesis, which benefits to form MCC. For the generating, maintaining and disappearing of MCC, we can see from the radial velocity map of CAPPI（1.5 km） ： The southwest low-level jet forms first, then the cyclonic or radial convergence on left appears; combing with moving eastward and turning to southward of severe convective cloud zone similar to squall line, large-scale of radial and severe divergence area is formed. Weakening and vanishing of low-level jet predicts weakening and dissipation of MCC.