池州市一次汛期暴雨过程诊断分析

Diagnostic Analysis of a Rainstorm Process in Chizhou City

利用NCEP 1°×1°再分析气象资料、地面气象观测数据和雷达资料,对2015年7月22—25日池州的一次大暴雨天气过程进行诊断分析,结果表明,此次暴雨发生在大陆高压和西太平洋副热带高压之间的高空槽前部,多个中尺度低涡系统造成强降水;强降水区出现在低层急流轴的左前方,中高层有冷空气侵入,这种低层暖平流、高层冷平流的上下层配置,以及低层辐合、高层辐散的耦合机制利于暴雨发展。水汽、热力、动力等物理量随时间的变化与降水有很好的对应关系;雷达图有中α尺度雨带,形成"列车效应",强回波呈短时强降水"低质心"特点;低空急流正对山区,且迎风坡降水大于背风坡,说明地形抬升对强降水有一定的贡献。

Using NCEP/NCAR reanalysis data with 1°×1° horizontal resolution, surface meteorological observation date and radar data, we analyzed a heavy rainstorm process in Chizhou from July 22 to 25, 2015.The results showed that the rainstorm occurred in the front of the high-altitude trough between the continental high and western Pacific subtropical high with multiple mesoscale low vortex systems caused heavy precipitation;the strong precipitation area appeared in the upstream left of the low-level jet, and cold air intrusion occurred in the middle and upper levels.These configurations of low-level warm advection and upper-level cold advection coupled with low-level convergence and high-level divergence were conducive to the development of heavy rain.The change of physical quantity such as water vapor, heat and power with time had a good correspondence with precipitation;the radar map had a medium-scale rainband, forming a “train effect”, and a short-term heavy precipitation characterized by the strong echo and “low centroid”;the low-level jet was facing the mountainous area, and the windward precipitation was larger than the leeward, indicating that the terrain uplift impact had a certain contribution to the strong precipitation.