华南北部冰雹天气的多尺度分析

Multi-scale Analysis of a Hail Event in the North of the South China

利用高空、地面等常规气象资料和雷达、自动站等气象观测资料,以及NCEP FNL分析资料,对华南北部一次冰雹天气进行多尺度分析,以探讨、总结这次冰雹天气过程形成、维持、发展成因及异同。结果表明:1)本次冰雹天气过程是在南支槽前、中低层切变线以及地面倒槽的形势背景之下发生的;中层干空气的夹卷、强垂直风切变和辐合抬升有利于冰雹天气发生;中高层干冷、低层暖湿的层结配置,导致大气层结的不稳定;高空辐散以及中层急流的配置,为冰雹天气过程提供了有利的动力条件; 2)相较而言,湖南南部的整体环境条件更为有利,对对流风暴有组织发展、冰雹的形成有明显的增强作用;而江西南部中上层极干,加上强的垂直风切变,和高层辐散强抽吸作用,有利于对流风暴的强度维持; 3)本次冰雹天气过程雷达回波特点明显。回波单体剖面出现了在过山阶段初为成熟阶段超级单体回波形态,而过山时变为悬空、不接地的单体初生回波形态的现象;超级单体回波的基本反射率图上,呈现出特殊的形状为细长型的类双弓形回波。

The multi-scale analysis of a wide range hail event occurred in the north of the south china was performed with various data including conventional observation data with regard to high altitude and ground, Doppler-Radar data, observations from automatic weather stations, reanalysis data from NECP FNL,etc. which use to discuss and summarize the cause concerning formation, keep, growth and its similarities and differences of the hail event. The results indicate that the hail event occurs under favorable ebvironmental conditions ： 1 ） This hail event occurs in the front of southern branch trough, the middle-low level of shear line and surge chamber of surface. The entrainment about mesosphere dry air, strong wind shear and convergence which could be propitious to the occmfence of hail event. Unstable stratification is formed by the dry and cold airflow in the ntis-high level and the warm and humid airflow in the low level. The configuration of the middle jet and diverge of high-rise provide a favorable dynamic conditions. 2） By contrast,the environmental condition in the south of Hunan is more favorable,which has obvious positive effect to organization develop of convective storm and the formation of hail. While, it, s in favor of convective stoml to maintain its intensity, which is the highly dry airflow in the middle and upper layer atmosphere, strong wind shear and the upper divergence pumping action. 3 ） The radar echos about this hail weather process has obvious features. It is the mature configuration echo section in the begin of passing over a mountain, while the configuration become impending and earth-free. In the base reflectivity of supercell, there is a special slightness echo,s form like diapsida.