河北省一次强对流天气机理分析

利用常规天气资料、气象自动站加密观测资料及乡镇加密雨量站资料、其它物理量资料及卫星云图资料等,对2009-06-08河北省的强降水及强对流天气进行了分析。研究表明,蒙古低涡携带强的正涡度平流和冷空气,为强对流天气提供了良好的动力条件;南风与偏东风急流为大暴雨提供了良好的水汽,同时,低涡底部的西北风急流与2支暖风急流汇合,为暴雨、冰雹、大风等强对流的形成提供了条件。暴雨落区处于低层次大值能量场的顶部,能量场剖面具有鞍形场结构,高层、低层具有大值能量,中层为中性结构,为深对流的发展提供了初始热力条件。自动气象站加密风场资料分析表明,长时间的中小尺度风场辐合增强了地面空气的辐合抬升,同时也是造成此次局地大暴雨的中尺度系统和触发条件。

Mechanism Analysis of a Strong Convective Weather in Hebei Province

An analysis for the heavy rain and strong convective weather at night on 8 June 2009 in Hebei Province was performed using conventional data,surface intensified observational data,rainfall of automatic weather stations,physical quantity and satellite image,etc.Results indicated that the vast vorticity advection and cold air of the Mongolian vortex provided dynamical condition for the strong convection;Southerly and easterly jet stream provided rich water vapour,while the confluence of northwesterly jet stream of the low vortex with two warm jet streams facilitated the formation of the torrential rain,hailstone and gale.Strong rain districts were all located in the top part of lower-level energy field,the profile of energy field had a col structure,which had large energy in upper and lower layers,neutral in middle-level,which provided an initial thermal condition for the deep convection.Intensified observational data of wind field showed that the extended meso-microscale wind field convergence enhanced the lifting convergence of surface air,resulting in this mesoscale system and triggered condition of the local torrential rain.