急流次级环流对局地持续强风暴天气的作用

利用天气图、雷达回波和地面风场资料对1994年6月28日陕西中部发生的一次罕见的长时间局地大风、冰雹、暴雨天气进行诊断分析。结果表明：这次过程出现在500hPa槽前和700hPa低涡暖式切变线附近；强风暴发生在高空急流入口区右侧辐散和低空急流左前侧辐合重叠区，与地面中尺度气旋活动紧密相关；证实了地面中尺度气旋是由高低空急流耦合产生的次级环流引起，次级环流控制着中尺度系统发展变化。

Effect of Jet Sub-Circulation on a Local Lasting Heavy Rainstorm

A diagnostic analysis was made of a local lasting heavy rainstorm took place in the central part of Shaanxi Province on 28 June 1994. The heavy rainstorm appeared in the front of a 500 hPa trough near the shear line of a depression on the 700 hPa, happened in the superposed zone between the right divergence area around the entrance of the upper-troposphere jet and the left convergence area of the lower-troposphere jet, and was related with the mesoscale cyclone on the surface. The diagnostic results show that the mesoscale cyclone on the surface was caused by the sub-circulation resulted from the coupling of upper and lower jets and the sub-circulation controlled the development and change of mesoscale systems.