1987年3月13日浙南地区强对流过程分析

本文对1987年3月13日浙南地区强对流过程发生的条件作了分析。强对流发生前36小时内,静力不稳定能急剧增加,发生前12小时已达到相当大的正值,不稳定能增大的主要原因是850百帕上有强而持久的暖湿平流。利用带通滤波法对地面气象要素进行尺度分离,发现这次过程与一中尺度低压的活动有密切关系。中低压伴有一较强的中尺度辐合中心,强对流天气首先在辐合中心附近暴发,然后向下游传播。该辐合中心很可能是这次过程的主要促发机制。地面中低压的形成和维持,与环境场的相对辐散及暖平流有关。

Analysis of Southern Zhejiang Severe Convective Event on 13 March 1987

The occurrence condition of southern Zhejiang severe convective event on 13 March 1987 is analyzed.The static instability energy increased apidly during 36 hours prior to the outbreak of the severe convection and reached a considerable positive value 12 hours before the event. The main reason of the increasing of instability energy is the strong and sustained advection of warm and moist air. The scale separation analysis for surface meteorological fields is run by the bandpass filter. It is found that this event is closely related to a mesoscale surface low. The low is associated with a s rong mesoscale convergence cell, near which the severe weather occurred init ally and then propagated downstream. The main triggering mechanism for this event may be caused by the strong mesoscale convergence cell. The formation and maintenance of the mesoscale low are related to the relatfve divergence and warm advection in environmental fields.