高原涡与西南涡耦合作用的个例诊断

A Case Study on Coupling Interaction between Plateau and Southwest Vortexes

对1982年7月26～28日由500hPa高原低涡与850hPa四川盆地浅薄低涡耦合作用引发盆地低涡强烈发展与大面积特大暴雨天气发生的机理进行了诊断研究。结果表明,高原低涡东移到100°E附近时,其低涡东部的正涡度平流与负值非平衡强迫与850hPa四川盆地浅薄低涡发生垂直叠加时,两者之间发生耦合作用。导致盆地浅薄低涡与500hPa高原涡同时发展,四川盆地发生大面积暴雨。

The evolution of southwest vortex and the occurrence of heavy rain caused by the coupling interaction between Plateau and southwest vortexes during the period of 26～28 July 1982 are diagnosed. The results show that, when the Plateau vortex moving eastward near 100°E, the positive vorticity advection and the negative unbalanced force in the east part of the Plateau vortex on 500 hPa imposed on 850 hPa southwest vortex occurred the vertical superposition. The coupling interaction between both the vortexes leads to the development of the southwest vortex and the occurrence of heavy rain.