2020年8月13—14日山东临沂一次暴雨天气过程分析

Analysis of a Rainstorm Weather Process in Linyi,Shandong Province from August 13 to 14,2020

利用常规气象资料、NCEP再分析资料等气象数据,对2020年8月13—14日山东临沂一次暴雨天气过程进行分析。结果表明:此次暴雨天气发生之前,亚欧大陆中高纬区域主要呈现“两槽一脊”的大气环流形势,2个低槽区分别处于咸海与里海,高压脊分布在贝加尔湖一带;此次暴雨天气是在高空槽、台风“米拉格”、低层切变线、低层低涡以及西南暖湿气流的共同影响下产生的;在副热带高压外围气流和槽前西南气流共同影响下,凭借低空急流构建的水汽输送带,持续将丰富的水汽向降水落区输送,为此次临沂市暴雨天气的发生提供了良好的水汽条件;强降水发生之前,临沂上空区域低空属于较强的正涡度中心,高空属于负涡度中心,负涡度中心在临沂上空偏东区域,意味着这个时候低层为辐合,高空为辐散状态,临沂上层分布着很强的上升运动,同时存在倾斜性,为此次强降水天气的形成提供了较好的动力条件;对流层低层湿正压项负值区反映了暴雨落区的分布情况。

Using conventional meteorological data and NCEP reanalysis data,this paper analyzed a rainstorm weather process in Linyi,Shandong province from August 13 to 14,2020.The results showed that before the rainstorm,the atmospheric circulation situation of“two troughs and one ridge”was mainly presented in the middle and high latitudes of the Eurasian continent,and the two low troughs were located in the Aral Sea and Caspian Sea respectively,High pressure ridge is distributed in Baikal Lake;The rainstorm was produced under the joint influence of high trough,typhoon“tmilag”,low-level shear line,low-level vortex and warm and humid airflow in Southwest China.Under the joint influence of the peripheral air flow of the subtropical high and the southwest air flow in front of the trough,relying on the water vapor conveyor belt constructed by the low-level jet,the rich water vapor was continuously transported to the precipitation area,which provided good water vapor conditions for the occurrence of the rainstorm in Linyi city.Before the heavy rainfall,the low altitude over Linyi belonged to a strong positive vorticity center,and the high altitude belonged to a negative vorticity center.The negative vorticity center was in the east area over Linyi,Shandong province,which meant that at this time,the low level was convergent and the high altitude is divergent.There was a strong upward movement and inclination in the upper layer of Linyi,This provided better dynamic conditions for the formation of this heavy precipitation weather.The negative value area of wet barotropic term in the lower troposphere reflected the distribution of rainstorm area.