辽宁2021年7月13日局地大暴雨成因分析

Analysis of Causes of Local Downpour on July 13, 2021 in Liaoning

2021年7月13—15日,辽宁出现明显降水天气,其中鞍山岫岩和丹东凤城出现大暴雨。利用常规气象观测资料、NCEP 1°×1°逐6 h再分析资料、卫星资料和雷达资料对此次强降水过程成因进行分析。结果表明:在强的副热带高压阻挡下,500 hPa高空槽移动缓慢;700、850、925 hPa持续强劲的西南风低空急流为此次暴雨的主要触发系统;超低空急流最大风速出口区辐合及迎风坡地形抬升为暴雨提供了辐合抬升的动力条件;由于低空急流持续输送作用,暴雨区低层水汽通量较大,水汽十分充沛;热力条件较好,低层高温高湿,强降水区上空为能量锋区。

There was significant precipitation in Liaoning, including heavy rain in Xiuyan of Anshan and Fengcheng of Dandong on July 13, 2021. The causes of the heavy precipitation process were analyzed by using conventional meteorological observation data,NCEP 1°×1° 6 h reanalysis data, satellite data and radar data, the results show: blocked by the strong subtropical high, the 500 hPa upper trough moves slowly. The continuous strong southwesterly low level jet at 700, 850and 925 hPa was the main trigger system of this rainstorm. Convergence in the outlet area of the maximum wind speed of the ultralow level jet and topographic uplift of the windward slope provide dynamic conditions for convergence uplift of the rainstorm. Due to the continuous transport of low-level jet,the water vapor flux in the lower layer of the rainstorm area is large and the water vapor is very abundant. The thermal conditions are good, with high temperature and humidity in the low layer and an energy front over the strong rainfall area.