贵州一次两高切变型大范围暴雨天气过程分析

Analysis of a Two-High Shear-Type Widespread Heavy Rainfall Process in Guizhou

摘要: 本文主要利用常规气象观测资料、区域自动站资料、FY-2卫星资料以及NCEP 1˚ × 1˚ 6 h再分析资料，从影响系统、环境场条件和水汽、热力、动力条件等方面，对2021年6月9日至10日贵州出现的一次两高切变型大范围暴雨天气过程总结分析。结果表明：此次由两高切变在缓慢东移南下过程与中低层切变及地面辐合线耦合造成的贵州大范围暴雨过程水汽充足，700 hPa比湿达到10~11 g∙kg⁻¹，850 hPa比湿达到12~14 g∙kg⁻¹；垂直速度从500 hPa到850 hPa贵州上空均为负值，最大垂直速度达到−0.3 Pa∙s⁻¹，上升运动强；贵州从低层到高层均处于高能舌区，假相当位温随高度减小，大气层结不稳定；造成此次强降雨的对流云团其影响主要分为四个阶段，对流云团强烈发展、缓慢东移北抬，并形成MCS，云顶亮温(TBB)最低达到−80℃~−70℃之间；对流云团在发展过程中具有明显的“列车效应”，这也是造成此次强降雨的主要原因。

Abstract: Based on conventional meteorological observation data, regional automatic station data, FY-2 satel-lite data, and NCEP 1˚ × 1˚ 6 h reanalysis data, this paper summarizes and analyzes a two-high shear-type widespread heavy rainfall process in Guizhou from June 9 to 10, 2021 from the aspects of influence system, environmental field conditions and water vapor, thermal and dynamic conditions, etc. The results show that: this large-scale rainstorm process in Guizhou, which is caused by the coupling of the two high shear, the middle low shear and the ground convergence line in the process of slowly moving eastward and pressing southward, has sufficient water vapor, and the specific hu-midity of 700 hPa reaches 10~11 g∙kg⁻¹, 850 hPa reaches 12~14 g∙kg⁻¹; The vertical velocity is negative over Guizhou from 500 hPa to 850 hPa, and the maximum vertical velocity reaches −0.3 Pa∙s⁻¹, indicating strong upward movement; Guizhou is in the high energy tongue from the lower to the upper levels, and the pseudo local temperature decreases with height, the atmospheric stratification is unstable. The influence of convective cloud cluster that caused this heavy rainfall is mainly divided into four stages. The convective cloud cluster develops strongly, moves slowly eastward and moves northward, and forms MCS. The minimum cloud top bright temperature (TBB) is between −80˚C and −70˚C. The convective cloud cluster has obvious “train effect” in the development process, which is also the main reason for this heavy rainfall.