一次高压坝背景下秋季对流性暴雨天气过程分析
Process in Autumn under the Background of High Pressure Dam

为进一步认识副热带高压控制条件下秋季对流性暴雨的发生发展机制，本文利用常规气象观测资料、区域自动站资料、NCEP 1？ × 1？逐6 h再分析资料，从环流背景、影响系统以及水汽、热力、动力诊断入手，对2021年9月6日傍晚到夜间贵州东部大范围对流性暴雨天气过程进行综合分析。结果表明：1) 此次对流性暴雨天气过程是在副高西伸北抬形成高压坝的背景下，中高纬冷涡低槽与高原东移的短波槽在四川东部同位相合并加强东移，引导低层切变线和地面冷空气南下，冷空气从贵州西北部和湖南西部入侵，在贵州东部地区形成两个冷池，冷池出流与前部的暖湿空气强烈交汇，触发对流性暴雨。2) 过程环境风较弱，水汽辐合主要集中850 hPa及以下，暴雨发生前弱偏南风从南海输送水汽，暴雨发生期间，水汽主要来源于本地，暴雨发生在850 hPa准南北向切变线附近的强水汽辐合区。3) 贵州东部850 hPa及以下为准南北向假相当位温高能舌控制，中层700~600 hPa有低能舌侵入，大气暖湿极不稳定，暴雨落区分布在准南北向等值线密集的能量锋区偏向高能区一侧。4) 锋生加强和涡度低层辐合、中高层辐散的动力配置，为暴雨的产生提供了动力条件，函数正值区与850 hPa切变线移动和分布一致，暴雨发生在锋生函数正值中心值达最大、锋生最强之后，强降雨随着锋生函数值减小而减弱，暴雨落区分布在准南北向锋生函数正值中心前沿等值线密集区。
In order to further understand the occurrence and development mechanism of convective rainstorm in autumn under the control of subtropical high, this paper uses conventional meteorological observation data, regional automatic station data, and NCEP 1？ × 1？ 6 h reanalysis data to compre-hensively analyze the large-scale convective rainstorm weather process in the east of Guizhou from the evening to the night of September 6, 2021, starting with the circulation background, influence system, water vapor, heat and dynamic diagnosis. The results show that: 1) This convective rainstorm weather process is under the background that the subtropical high extends westward and uplifts northward to form a high-pressure dam. The mid high latitude cold vortex trough and the short wave trough moving eastward from the plateau are in the same phase in eastern Sichuan, strengthening and moving eastward, leading the low-level shear line and the cold air on the ground to the south. Cold air invades from northwest Guizhou and western Hunan, forming two cold pools in eastern Guizhou. The outflow of the cold pool strongly intersects with the warm and humid air in the front, trigger convective rainstorm. 2) The process environment wind is weak, and the water vapor convergence is mainly concentrated at 850 hPa and below. Before the rainstorm, the weak southerly wind transports water vapor from the South China Sea. During the rainstorm, the water vapor mainly comes from the local area, and the rainstorm occurs in the strong water vapor convergence area near the quasi north-south shear line at 850 hPa. 3) In the east of Guizhou, 850 hPa and below are controlled by quasi south-north pseudo equivalent potential temperature high energy tongue. In the middle layer of 700~600 hPa, there is low energy tongue intrusion. The atmosphere is warm and humid, and extremely unstable. The rainstorm area is distributed in the energy front