2020年8月16日龙泉驿区暴雨天气过程分析

Analysis of the Stormy Weather Process in Longquanyi District on 16 August 2020

摘要: 利用2020年8月14~16日的逐日NCEP/FNL再分析资料，网格距1˚ × 1˚，时间间隔为6 h，龙泉驿区本站的24小时逐日降水观测资料，对2020年8月16日龙泉驿区暴雨天气过程进行分析，结果表明：1) 2020年8月16日暴雨过程中，100 hPa南亚高压脊线位置位于35˚N附近，500 hPa副高脊线位于25˚N左右，700 hPa四川盆地上空存在切变线和西南低空急流，850 hpa西南低涡逐渐东移与副高西北侧西南低空急流相互作用，从而诱发暴雨的产生。2) 热力条件和动力条件诊断分析表明：此次暴雨天气过程，假相当位温在600 hpa以下随高度的升高而减小，表明暴雨发生过程中层结不稳定，低层正涡度的气旋性运动与高层负涡度的反气旋运动相互作用，且为大气上升运动提供抬升条件，由西南急流所运输的来自孟加拉湾和南海的水汽，为此次暴雨天气过程提供了充沛的水汽条件。

Abstract: Using the day-by-day NCEP/FNL reanalysis data from August 14~16, 2020, with a grid distance of 1˚ × 1˚ and a time interval of 6 h, and the 24-hour day-by-day precipitation observation data from the Longquanyi District Station, the weather process of the heavy rainfall in Longquanyi District on August 16, 2020 was analyzed. The position of the 100 hPa South Asian high pressure ridge was located near 35˚N, the 500 hPa vice high ridge was located at about 25˚N, there were shear lines and southwest low-level rapids over the Sichuan basin at 700 hPa, and the 850 hPa southwest low vortex gradually moved eastward and interacted with the southwest low-level rapids on the northwest side of the vice high, thus inducing the heavy rain. 2) The diagnostic analysis of thermal and dynamic conditions shows that the pseudo-equivalent level temperature below 600 hpa decreases with the increase in altitude, indicating that the stratification is unstable during the rainstorm, and the cyclonic motion of positive vorticity at the lower level interacts with the anticyclonic motion of negative vorticity at the upper level, and provides lifting conditions for the upward movement of the atmosphere. The water vapour from the Bay of Bengal and the South China Sea, transported by the southwest rapids, provided abundant water vapour conditions for the storm.