惯性稳定性在伴有高低空急流的暴雨中的作用

The Role of Inertial Stability in Heavy Rain Accompanied by Upper and Low Level Jets

摘要:

通过对低空西南急流左前方和高空偏北大风轴右后方的惯性稳定性和对称稳定性的理论分析和实例计算,表明:低空急流左前方惯性稳定度大值区的存在,有利于低层湿热能量的积累,使低层倾斜对流的不稳定发展更多期望于条件性对称不稳定或对流不稳定;高空偏北大风轴(西风急流)的存在,是其右后方(右侧)出现对称不稳定的有利条件,高空相对容易出现干对称不稳定;惯性稳定性的作用,使低层的倾斜对流更偏向于垂直方向,有利于对流发展,使高层的倾斜对流更偏向于水平方向,有利于高层辐散。

关键词:惯性稳定性;低空急流;倾斜对流;对称不稳定

Abstract:

The important effect of inertial stability on heavy rain accompanied by low level south-westerly jet and upper level northerly strong flow is analyzed theoretically in this paper.The results show that the existence of the maximum of inertial stability in the left front of the low level jet is favorable to the accumulation of moist thermal energy and that the conditional symmetric instability or convective instability can be expected in this region.The maintenance of the upper level strong flow provides a beneficial circumstance for the generation of the dry symmetric instability in its right rear region.Furthermore,the inertial stability can cause a slantwise convection at low level more vertical and therefore support the convection,which in turn makes the slantwise convection more horizontal at upper level and benefits the divergence over there.

Key words:inertial stability;low level jet;slantwise convection;symmetric instability