2019年5月初宁夏一次连阴雨过程分析

Analysis of a Continuous Overcast Rain Process in Ningxia in Early May 2019

利用常规气象观测资料、NCEP/NCAR再分析资料(2.5°×2.5°)等,应用天气学原理和天气动力学诊断分析方法,从环流背景、系统发展演变、物理量场等方面,对2019年5月5—8日宁夏一次连阴雨天气过程进行分析。结果表明:500 hPa乌拉尔山高压脊和巴尔喀什湖低涡的稳定存在和“东高西低”形势的建立与维持为连阴雨过程提供了大尺度环流背景,中低层持续的切变线活动有利于降水的持续,符合宁夏连阴雨的预报模型。低层能量锋区和不稳定层结的存在、下负上正的涡度平流垂直分布和整层持续的上升运动,提供了良好的热动力机制;地面洄流形势和偏东南大风速带对水汽有较好的输送作用。

Based on the conventional meteorological observation data and NCEP/NCAR reanalysis data(2.5°×2.5°), this paper analyzed a continuous cloudy and rainy weather process in Ningxia from May 5 to 8, 2019 from the aspects of circulation background, system development and evolution, physical quantity field and so on.The results showed that the stable existence of 500 hPa Ural Mountain high ridge and the low vortex of Balkash lake and the establishment and maintenance of the situation of “high in the East and low in the west”provide a large-scale circulation background for the continuous rain process. The continuous shear line activity in the middle and low layers was conducive to the continuous precipitation,which was in line with the prediction model of continuous rain in Ningxia. The existence of low-level energy front and unstable stratification, the vertical distribution of lower negative and upper positive vorticity advection and the continuous upward movement of the whole layer provided a good thermal dynamic mechanism;The surface migration situation and the southeast high wind speed belt had a good transport effect on water vapor.