“0730”上海强对流天气个例的中尺度观测分析及数值模拟

Mesoscale Observation and Simulation on 30 July 2005 Severe Convective Case in Shanghai

利用上海多普勒雷达、中尺度自动站等资料和中尺度数值模式WRF模拟结果,分析了2005年7月30发生,在上海地区的一次强对流天气(简称"0730")的发生、发展过程。结果表明,边界层中尺度辐合线和扰动能够在弱冷空气南下和局地中小尺度斜压不稳定的背景下产生,中尺度扰动不稳定随垂直运动上传、触发对流;低层高湿度梯度的大气层结、垂直风向剧烈非均匀切变和能量锋区的耦合配置,促进了强对流的迅速发展。结合数值模拟和诊断分析初步揭示了这次强对流过程发生冰雹、暴雨、大风等天气的原因。

A severe convective case,occurring in Shanghai on 30 July 2005,is examined with the composite datasets from WSR-88D Doppler radar,automatic weather stations and mesoscale numerical model WRF. It is found that the occurrence of mesoscale convergence lines was mainly induced by the southward intrusion of weak cold front and the pre-existed local mesoscale baroclinic instability.The growth of these mesoscale boundary layer disturbances within the convergence lines was favored by the dynamical cooperation among high gradient of moisture,strong vertical wind shear,and energy front within the lower troposphere, resulting in the abrupt growth of the convection.Mechanisms for the simultaneous occurrence of hail,heavy rainfall and gale during this severe convection are also analyzed.