西南低涡东移对华南暴雨增幅的动力机制分析

对1996年6月13~14日华南大暴雨发生过程的天气形势和物理量场进行分析,并从中尺度能量方面探讨了西南低涡对华南暴雨增幅的动力机制。结果表明:暴雨的发生与西南低涡及850hPa孟湾地区的水汽通量有着密切的联系;而500hPa较强的负螺旋度有利于低层低涡的发展加强;暴雨发生前,华南上空维持一支反气旋性的西南急流,当西南涡东南移时,造成本地重力惯性波能量增加,从而对华南暴雨有正贡献,即对暴雨有一定的增幅作用。

Dynamic Analysis for Southwest-vortex Moving to East can Increases The South China rainstorm

The synoptic situation and physics quantity field of the rainstorm process in South China from June 13th to June 14th,1996 is analyzed.And the dynamical mechanism of the amplitude effect caused by the Southwest-vortex is discussed on the point of meso scale energy.Results show that Southwest-vortex and the vapor flux in the Bengal Bay on the 850hPa were closely related to the heavy rain event.The minus helicity at 500hPa was propitious to the development of low pressure at lower layer.The anticyclonic Southwest jet before the rainstorm producing caused the increasing of energy of inertia gravitational wave and had the positive contribution to the rainstorm of South China,which means it had some increasing effect to the rainstorm.