Abstract:

The causes of the regional heavy rainstorm in Inner Mongolia's western and eastern regions from August 16 to 18, 2016 were discussed using the routine and automatic weather stations observational data, NCEP (1°×1°) reanalysis data, FY-2E satellite cloud pictures and Doppler radar data. The results show that the edge of the West Pacific Subtropical High, “人” shaped shear line on 700 hPa and 850 hPa, and isobar dense zone in the front of Hetao cyclone  were direct influence systems that caused extreme rainstorm. The deep wet layer and notable increase of humidity in the low level which happened 6 hours before the extreme rainstorm provided adequate water vapor for the extreme rainstorm.The covergence center and strong ascending motion overlapped and enhanced, which was more conducive to formation of a strong upward movement, it was the development and maintenance mechanism of heavy rain. The effective convective energy (CAPE) enhanced significantly, the thickness of the warm clouds increased, they were conducive to the generation of high precipitation efficiency. There were two meso-scale convergence systems (MCS) moving from west to east through the edge of subtropical high 584 dagpm line and Yinshan Mountains.There was a good corresponding relationship between the short-time strong rainfall more than 30 mm·h-1 and the TBB  low center(equal and more than -52 ℃)and the strong TBB gradient.

Key words: heavy rainstorm, precipitation efficiency, MCS, TBB, Inner Mongolia

摘要：

利用常规观测资料、自动加密站观测资料、NCEP（1°×1°）再分析资料、FY-2E卫星云图以及多普勒雷达资料，对2016 年8月16—18日内蒙古中西部区域性极端大暴雨天气的成因进行分析。结果表明：暴雨落区位于副热带高压边缘、700～850 hPa“人” 字型切变线、河套气旋前部等压线密集处的叠置区；深厚的湿层以及极端暴雨发生前6 h中低层显著增湿为暴雨的发生输送了充沛的水汽；散度辐合中心和上升运动中心叠置且加强，更有利于强烈上升运动形成，是暴雨发生发展和维持的动力机制；暴雨爆发前对流有效位能（CAPE）有明显跃升，暖云层厚度加大，有利于降水效率的提高；暴雨时段内有两个中尺度对流系统（MCS）以相同路线沿着副热带高压584 dagpm线边缘、阴山山脉东西方向自西向东移动；短时强降水（＞30 mm·h-1）和云顶亮温（TBB）低值中心区（≤-52 ℃）以及TBB等值线密集区有良好的对应关系。

关键词: 极端暴雨, 降水效率, MCS, TBB, 内蒙古