黑龙江省一次暴雨过程的中尺度特征与物理机制分析

Mesoscale features and dynamic mechanisms of torrential rain in Heilongjiang province

使用常规观测资料、物理量场、以及地面自动站资料,对2014年7月20-21日发生在黑龙江省的一次暴雨过程进行了诊断分析,得到:此次过程主要是由高空低涡、副热带高压和蒙古低压共同影响,暖锋触发的暴雨天气;低空西南急流输送暖湿空气,为暴雨提供充足水汽和动力条件,同时,中空急流与干舌配合输送干冷空气,两者叠加增强了大气的不稳定,暖锋锋生触发了对流性天气;渤海湾是此次暴雨主要的水汽源地,低层强烈的水汽输送和水汽辐合使大气湿度层迅速增厚,为暴雨的发生发展提供了有利的水汽条件。整层正涡度区有利于产生气旋性辐合上升运动,为暴雨提供了充足的动力条件。K指数、对流有效位能和假相当位温都指示了发生强对流天气的可能性。

Mesoscale features and dynamic mechanisms of the heavy rainfall happened on July 20-21,2014 are hollow jet with dry tongue convey cold air, the combination strengthened the instability of the atmosphere, fronto- genesis triggered the convectional weather;merging and strengthening of the mesoscale convective cloud cluster in the rainstorm is the main reason of the rainstorm process. Rain intensity was significantly enhanced with the de- velopment of cloud. Bohai bay is the main water vapor source of rainstorms, in the low level, intense water-vapor transfer and convergence made the humidity level increased rapidly which provide the rainstorm water vapor to develop.The whole positive vorticity area is conductive to generate cyclonic convergence upward motion and it provide ample power storm conditions. K index, convection effective potentials and fake a considerable potential temperature all indicate the possibility of strong convective weather.