2016年7月2~4日长沙特大暴雨天气过程技术分析

The Technical Analysis of the Heavy Rainfall Process in Changsha from July 2 to 4, 2016

摘要: 2016年7月2~4日长沙地区出现了历史罕见的特大暴雨天气，该文利用常规气象资料、卫星云图、雷达资料、NCEP再分析资料对此次过程进行分析，结果表明：1) 此次过程是副高减弱过程中发生于副高边缘的梅雨锋降水，以深厚高空槽与副高的长时间对峙、中低层切变线的长时间维持为背景；2) 在有利天气形势下，多个中β尺度对流单体不断生消，并持续影响长沙，使得长沙出现多轮短时强降雨；3) 雷达图上，长沙各地经历了多次对流单体的袭击，自西向东形成“列车效应”，出现雷雨大风时刻，在径向速度图上有明显的正负速度对；4) 强降雨发生期间，水汽输送带与低空急流位置相对应，大气可降水量大值区与水汽辐合区对应，长沙地区上空大气可降水量超过700 mm，对流层中低层存在着深厚的气旋性涡度区，高层的负涡度中心值较大，气流的“抽吸作用”强。

Abstract: There was a rare heavy rainfall in Changsha from July 2 to 4, 2016. This paper analyzed the process by using conventional meteorological data, satellite cloud maps, radar data, and NCEP reanalysis data. Results show that: 1) This process is the Plum Rains front precipitation that occurred at the edge of the subtropical high during the weakening of the subtropical high, with the long-term confrontation of the deep high-altitude trough and the subtropical high, and the long-term maintenance of the mid-lower shear line as the background; 2) Under favorable weather conditions, multiple medium-scale convective monomers continue to disappear and continue to affect Changsha, resulting in multiple short-term heavy rainfall in Changsha; 3) On the radar map, Changsha has experienced many attacks on convective cells, forming a “train effect” from west to east, and there was a significant positive and negative speed pair on the radial velocity map at the moment of thunder-storm and strong wind; 4) During the heavy rainfall, the water vapor conveyor belt corresponds to the position of the low-level jet stream, corresponding to the large-scale precipitation area of the atmosphere and the water vapor convergence area. Atmospheric rainfall was more than 700 mm above the Changsha region, and there was a deep cyclonic vorticity zone in the middle and lower troposphere. The central value of the negative vorticity of the upper layer was large, and the “suction effect” of the airflow was strong.