一次春季冰雹天气的中尺度系统分析

Analysis on the Mesoscale System of the Hail Weather in Spring

对2007年5月5日江苏出现的大范围雷雨、大风和区域性冰雹天气的环流背景场进行了分析,结果表明:这次强对流天气是由北方南下的冷空气触发所致,锋前对流层低层的增温和500 hPa冷空气的先行南下使潜在的对流不稳定性加剧;地面冷锋前中尺度低压的发展是对流性天气发展的主要因素;强烈的上升运动和低层水汽通量辐合提供了有利于冰雹产生的过冷水滴的碰撞增长条件;冰雹天气的产生与地面物理量场有很好的配置关系。

Based on the study of the circulation background, this study aimed to discuss the reasons that the widespread thunderstorm rain, gale and regional hail weather occurred in Jiangsu province in May 5, 2007. The results showed that the severe convective weather was caused by cold air slipping down Southward from the North, also the pro frontal temperature increased in the low troposphere and the cold air in 500hPa layer slipping down Southward earlier enhanced the latent convective instability and development of mesoscale depression in front of the cold front on the surface was one of the important reasons leading to convective weather. Strong ascending motion and moisture flux convergence helped the hail formation by strengthening supercooled water droplet agglomeration. The study also instated that hail weather is closely related with the physical parameter field on the surface.