黑龙江省一次大暴雨干侵入特征分析

Analysis of dry intrusion features of a heavy rainstorm in Heilongjiang Province

本文利用常规气象观测资料和欧洲中心ERA-Interim再分析资料结合FY-2F卫星云图,分析了2017年8月3日黑龙江中西部大暴雨天气成因及干侵入作用。结果表明:本次暴雨主要是由华北上空的低槽以及地面低压东移至黑龙江地区加强发展产生的,海上台风"奥鹿"和副热带高压西侧偏东、偏南气流为本次暴雨过程供应了充足的水汽;中高纬度的高空急流为暴雨的形成提供了动力条件;通过等熵面的物理量场分析,追踪到本次暴雨干侵入的源头在巴尔喀什湖附近的对流层顶附近,随中高纬度西风气流入侵到低压后部。干侵入促使高位涡下传引起中低层的位涡异常,诱发地面低压加强发展,为暴雨的产生提供垂直上升运动条件;干冷空气侵入并叠加在低层暖湿气流上,为强降水的产生提供了不稳定层结条件。

Using conventional meteorological observation data and ERA-Interim reanalysis data of European center,combining with FY-2F satellite cloud images,this article analyzes the causes and the dry intrusion of the heavy rainstorm in Heilongjiang province at august 3rd,2017.The results show that,the rainstorm is mainly caused by the low trough over North China and the ground low pressure,those move eastwards to Heilongjiang Province and finally develop strong.The sufficient water vapor for the rainstorm are supplied by the offshore typhoon"aolu"and the east and south air flow from the west side of the subtropical high.The upper-level jet of middle-high latitudes provides dynamic conditions for the formation of the rainstorm.By the analysis of the physical quantity fields on the isentropic level,the source of dry intrusion is traced up to the tropopause near Balk ash lake,which then intrudes into the back of the ground low pressure along with the westerlies of middle-high latitudes.The dry intrusion causes the anomaly of potential vorticity in the middle and lower layers,through the downward transmission of high potential vortex,and induces the development of the ground low pressure,which provides vertical motion conditions for the occurrence of the rainstorm.Intrusion and superposition of the dry and cold air onto the low-level warm and humid air flow,provide unstable stratification condition for the generation of the heavy precipitation.