一次鲁南大暴雨强降水成因分析

Aanalysis of Heavy Rainfall in South Shandong Province

利用大量常规和非常规资料,分析了发生在鲁南地区的一次大暴雨过程中强降水产生的原因,表明:本次大暴雨发生在副热带高压和西风槽之间形成的相对狭窄的急流锋区上,主要影响系统为低层切变线和南支槽作用产生的中小尺度低涡系统;该涡旋系统内涡度和散度同量级,散度的变化幅度要强于涡度的变化幅度,因此由大气在运动中的集中造成的辐合明显强于由风向的旋转造成的辐合,前者更高效。大气的集中得益于中高空西南气流和低空东南气流辐合,在水汽超饱和状态下,强烈辐合上升使得凝结迅速在较低层次完成,高效的水汽凝结短时间内在局地狭小区域形成致灾的超强降水。

Based on data,the heavy rainfall in South Shandong is analyzed.Results show that: the heavy rainfall occurred in the narrow jet between the suptropical high pressure and the westerly zone,the main influencing systemis small scale vortex system in the south-west airflow produced by low level shear line and the southern branch;the vorticity and divergence are at the same level;changes in amplitude is larger than the vorticity variation of amplitude;Covergence made by concentrationof atmosphere was stronger than that by wind caused by rotation of convergence,and the former is more efficient.