台风“利奇马”导致的山东降水成因分析

Analysis of precipitation in Shandong caused by typhoon Lekima

利用ECMWF提供的ERA5再分析数据,对2019年09号超强台风“利奇马”造成山东降水的原因进行了分析,探究此次降水的启动机制。结果表明,“利奇马”造成山东降水是对流发展形成的深厚系统,雨区的移动方向是由水汽辐合区向西北方向移动造成的。降水前期高空暖平流使高压脊发展形成高空急流,山东北部位于高空急流入口区右侧,为强辐散区。对流层低层的东南风提供了充足的水汽,水汽辐合上升,形成降雨。随着雨区移动,低层辐合区和高空辐散区重叠,发展为深厚对流,降水加强。高空辐散区的长时间维持是造成这次较长时间降水的主要原因。

The precipitation in Shandong caused by super typhoon Lekima in 2019 were analyzed.The starting mechanism of the precipitation was explored by using reanalysis data of ERA5 provided by the ECMWF.The results were as follows:the precipitation system in Shandong caused by Lekima was formed by the development of deep convection,and the movement direction of the precipitation was caused by the moisture convergence zone moving to the northwest.In early stage of the precipitation,pressure ridge was strengthened to form the upper-level jet stream by upper-level warm advection.The northern part of Shandong was located at the right side of upper-level jet stream entrance area corresponding to the strong divergence area.Sufficient water vapor was provided by the southeasterly winds in the lower troposphere,and then the water vapor rose to form rainfall.With the movement of the precipitation,the convergence area in the lower layer and the divergence area in the upper layer were overlapped and developed into deep convection.Then the precipitation was intensified.The long-term maintenance of the divergence area in the upper layer was the main reason for a long time precipitation.