湘黔边境一次高空槽前型飑线天气过程的成因分析

Analysis on the Forming Reason of A Squall Line Weather in Front of the Upper-Level Westerly Trough

综合多种观测资料,对2006年8月1日发生在湘黔边境的一次强对流天气过程的成因进行了分析。结果表明:这是一次典型的高空槽前型飑线过程,副热带高压的迅速东退、强湿度梯度及其南北两侧冷暖空气的辐合造成的强湿度锋锋生作用触发了强对流;强对流发生前和发生时大气层结的不稳定、良好的水汽输送及辐合条件对其发生发展十分有利;高层强辐散与低层强辐合的耦合形势以及强上升运动为强对流的发生发展提供了有利的动力条件。

The forming reason of a severe convective weather which took place in the frontier of Hunan province and Guizhou province was analyzed based on the observation data and reanalysis data. It showed that this was a typical squall line event in front of the upper-level westerly trough. The rapid eastward countermarch of Western Pacific Subtropical High, the strong humidity gradient and the strong moisture front-generating created by convergence of cold and warm air triggered the strong convection weather. The instability of atmospheric stratification before and during the occurrence of severe convection weather, good water vapor transfer and convergence condition were extremely advantageous to the development of the severe convective weather. The coupling between strong divergence in the high level and strong convergence in the low level and the existence of strong ascending movement provided the favorable dynamic conditions for the occurrence of the severe convective weather.