四川盆地一次区域性暴雨天气过程分析——2023年7月11日至14日

Analysis of a Regional Rainstorm Weather Process in the Sichuan Basin—July 11~14, 2023

基于成都信息工程大学气象台Micaps常规高空和地面观测资料、FY-2卫星云图资料和欧洲中心ERA5高分辨率再分析资料(0.25˚ × 0.25˚),本文对2023年7月11日至14日四川盆地发生的一次持续性暴雨天气过程进行了诊断分析。结果表明,200 hPa高空急流显著增强;对流层低层切变线、西南涡和低空急流的维持,地面冷空气的南下,共同形成了此次暴雨过程的有利环流背景。高层辐散与低层辐合的垂直结构,持续且强烈的水汽供应为此次暴雨的发生提供了有利的动力及水汽条件。进一步分析发现,在地形辐合抬升的作用下,四川盆地东北部有明显的水汽辐合中心,配合正涡度区进一步加强了垂直上升运动;高温高湿的环境有利于中尺度对流系统的维持和发展,分析卫星云图发现盆地上空对流云团发展旺盛,伴随着密实对流云团的移动暴雨落区也在移动,是本次暴雨天气的主要中尺度对流系统。Based on Micaps conventional upper-air and ground-based observations at the meteorological station of Chengdu University of Information Technology (CUIT), FY-2 satellite cloud map data and ERA5 high-resolution reanalysis data (0.25˚ × 0.25˚) from the European Center, this paper provides a diagnostic analysis of a persistent torrential rainfall weather process occurring in the Sichuan Basin from July 11 to 14, 2023. The results show that the 200 hPa upper-level rapids were significantly enhanced;the maintenance of lower tropospheric shear, southwesterly vortex and lower-level rapids, and the southward movement of cold air at the surface together formed a favorable circulation background for this rainstorm process. The vertical structure of upper-level dispersion and lower-level convergence, and the sustained and strong water vapor supply provided favorable power and water vapor conditions for the occurrence of this rainstorm. Further analysis reveals that, under the effect of terrain convergence and uplift, there is a clear water vapor convergence center in the northeastern part of the Sichuan Basin, which further strengthens the vertical uplift movement together with the positive vorticity area;the high temperature and high humidity environment is conducive to the maintenance and development of mesoscale convective systems, and the analysis of the satellite cloud maps reveals that there is a vigorous development of convective clouds over the Basin, and the rainstorm fallout area is moving along with the movement of the dense convective clouds, which is the main mesoscale convective system of the stormy rain.