引发暴雨的低涡发生发展机制分析

Mechanism of the Low Vortex's Generation and Development Which Produces Heavy Rainfall

应用位涡理论对2013年5月25-26日发生在我国中东部大范围的低涡暴雨过程进行分析,结果表明:位涡的引进可以追踪高层扰动,可以根据扰动位涡的变化来判断系统的发展,这为分析高层扰动提供了方便;高层位涡异常使其下方的气旋性涡度加强并向低层发展形成气旋性涡柱,涡柱移动到西南涡上空时使其东移发展,当气旋性环流作用到静止锋上锋生形成江淮气旋;西南涡发展与气旋的生成加剧了低层辐合而产生强降雨,强降雨出现在低层扰动湿位涡负中心移动方的前侧,负值越大降水越强,强降雨释放凝结潜热使位涡和气旋性涡柱爆发性增长。

Vortex rainstorm in the large range of middle east from May 25 th,2013 to May 26 th is analyzed by using the potential vorticity method and the results shows that： the quotation of the potential vorticity can trace the disturbance in the upper troposphere,the development of the system can be judged by the changes of disturbance potential vorticity which provides convenience for analyzing the disturbance in the upper troposphere. The abnormality of the potential vorticity in the upper troposphere makes the cyclonic vorticity be stronger and develop to the cyclonic vorticity column which makes Southwest Vortex move east and develop when it moves to the zenith of the Southwest Vortex,the Jiang-Huai Cyclone develops when the cyclonic circulation adds into the Stationary Front.The development of the Southwest Vortex and the generation of the cyclone intensifies low level convergence which produces strong rainfall,the strong rainfall locates in the front side of the moving direction of the negative center of MPV in the low-level,and the larger the negative value,the stronger the rainfall is. The latent heat of condensation released from the strong rainfall makes the potential vorticity and the cyclonic vorticity column increasing explosively.