鄂伦春自治旗一次暴雨天气过程诊断分析

Analysis on the Rainstorm Process in Oroqen Banner

文章综合利用常规观测资料、雷达回波资料、卫星资料,对2015年8月2—3日发生在鄂伦春旗南部的暴雨天气过程从环流背景和中尺度特征方面进行诊断分析,结果表明:500hPa高空槽和850切变线形成前倾结构,前倾槽结构为暴雨的发生发展提供了热力和动力条件;700、850hPa西南急流对鄂伦春旗低层增温增湿作用明显,加之地面、850hPa东南急流辐合上升,增加了大气层结不稳定度,这两支急流在鄂伦春旗上空形成了强烈的水汽通量的辐合。与地形因素相关联的近地面层切变辐合促成下边界层辐合是此次暴雨过程的触发点,其附近陆续生成的中等强度块状的对流单体,形成暴雨。此次暴雨过程的中尺度特征:影响云带主要由有序的中尺度对流云团和中尺度对流复合体组成,降水时空变率大,雷达回波强度达到60dBz,走向与低空切边线移动方向一致。

In this paper,the comprehensive utilization of conventional observation data,radar echo data,satellite data,on August 2-3,2015 in southern orogen flag from the circulation background and mesoscale heavy rain weather process characteristics diagnosis analysis,the results show that the 500 hPa upper trough and shear line 850 forward structure formation,forward slot structure for the occurrence of heavy rain development provides the thermodynamic and dynamic conditions;700 hPa and 850 hPa southwest jet flag low-rise warming humidification of orogen,combined with the ground,up 850 hPa southeast jet convergence,increase the atmosphere knot not stability,the two jet over the orogen flag to form the strong water vapor flux convergence.And terrain factors associated with the surface layer shear convergence to the boundary layer convergence is the trigger point of the heavy rain process,the succession of producing medium strength of the block near the convective cells,formation of rain.The mesoscale heavy rain process features：the impact cloud belt is mainly composed of an orderly mesoscale convective cloud cluster and mesoscale convective complexes,precipitation rate of change of time and space,radar echo intensity reached 60 dBz,to move in the same direction with a low cut edges.