2016年夏季我国一次大范围强降水变化特征分析

An Analysis of the Characteristics of a Large-Scale Heavy Precipitation in China during the Summer of 2016

摘要: 利用NCEP/NCAR再分析环流数据、FY-2F卫星数据和CMORPH融合逐时降水格点资料，基于大气环流背景下，对2016年6月19~23日发生的一次大范围强降水过程的降水强度、范围变化特征进行了主要分析。结果表明：受500 hPa高度场中高纬度稳定的两槽两脊结构的影响，低纬华南地区受西太平洋副热带高压的控制，以及青藏高原短波槽的影响，低涡在四川东部生成。高纬度槽和中低纬度西太副高的稳定维持为西南涡和华北上空低涡的东移和水汽输送创造了有利条件。大范围暴雨天气与我国深厚低涡系统的移动、强烈发展有关，西南地区的700 hPa低涡向东北方向移动，移动过程中低层低涡逐渐加强，西南地区和华北地区的涡度系统合并，涡度的空间结构发展成垂直的低涡系统，暴雨的发展过程和低涡系统的发展过程基本一致。涡度正值中心存在明显速度辐合区，气流在低层辐合，高层辐散，对流上升运动发展剧烈，不稳定能量大量释放，为暴雨天气发生创造了有利条件。此外，涡度分析也表明在正值中心向东移动，对应暴雨的降水中心也向东移。

Abstract: Using NCEP/NCAR reanalysis circulation data, FY-2F satellite data and CMORPH hourly precipitation grid point data, the precipitation intensity and range variation characteristics of a large-scale heavy precipitation process occurred from June 19-23, 2016 were analyzed. The results show that under the influence of the stable two-trough and two-ridge structure in the 500 hPa geopotential field, the low-latitude south China area is controlled by the western Pacific subtropical high and the Qinghai-Tibet Plateau short-wave trough. The low-latitude vortex is generated in the east of the Sichuan basin. The stability of the high latitude trough and the western subtropical high over middle and low latitudes creates favorable conditions for the eastward movement of the low eddy over the southwest and North China vortexes and water vapor transport. The large scale heavy rain has a close relation to the movement and development of the deep low vortex system of China. The 700 hPa low pressure vortex over southwestern China can move towards to northeastern and became strengthened gradually during the movement process. Furthermore, the low pressure vortex system over southwestern and northern China gradually merged and its spatial structure developed into vertical vortex system. The development process of rainstorm is basically consistent with that of vortex system. In the center of positive vorticity, there is an obvious velocity con-vergence zone. The airflow converges in the lower troposphere and diverges in the higher tro-posphere. The upward movement of convection develops violently. In addition, the vorticity anal-ysis also shows that the center of precipitation moves to the east in the positive value, and the center of precipitation corresponding to the rainstorm also moves to the east.