重庆2008年7月21日强对流天气成因及其特征

对2008年7月21日重庆市一次强对流天气过程进行诊断分析,通过分析天气背景,雷达回波,并应用四维变分同化方法反演风场,研究了强对流天气的发展机制.结果表明:高层冷空气入侵和中低层低涡系统强盛的暖湿气流形成的辐合切变是发生强对流的主要原因.雷达观测具有明显的弱回波区和"逆风区";反演水平风场表现为低层强回波前部有一条辐合上升带,到中层辐合上升带与强回波区重合,高层则对应辐散区;从风场的垂直剖面来看,强对流后部为入流区,到达中部后,形成强烈的上升气流,低层辐合带和强烈的上升气流形成强回波.在前部弱回波区处存在强降水下落形成的出流,该气流与暖湿气流辐合造成了浅薄的出流边界.

Analysis on Causation and Character of a Strong Convection Event on 21 July 2008 in Chongqing City

A strong convection event on 21 July 2008 in Chongqing City was diagnosed. The developing mechanism of the strong convection weather was studied with the background of weather, the echoes of radar and the wind field computed by 4D-VAR technique. The results indicate that the strong storm was caused by atmospheric convergence, which was brought by upper cold air inrush and lower warm-wet airflow intersection. Observation of radar shows that there were a weak echo field and "adverse wind region". Low level wi...