苏南一次深秋局地强对流的多源资料分析

针对2014年苏南地区深秋一次强对流天气过程,运用雷达、闪电定位仪、风廓线雷达和雨滴谱仪分别对强对流天气过程进行分析,发现新探测资料对于强对流的发生和发展有一定提示作用。本次天气过程主要是在前期回暖明显,西南气流强盛,有高空槽引导冷空气南下,冷空气的入侵导致了局地强对流的发生。深秋强对流发生的各种潜势与汛期强对流形成的阈值明显不一样,虽然不稳定能量没有春夏高,但在动力条件下触发低层冷空气强烈抬升暖湿空气,继而引发局地冰雹。雷达数据与汛期强对流的各种指标对比表明:无锡地区冰雹回波结构与汛期发生的冰雹个例相比,垂直累积液态水含量和回波顶高明显下降,这与季节的不同有明显关系,热力条件已无春夏好,季节的原因导致回波顶高偏低。通过闪电资料的统计表明:闪电频数的突然上升说明超级单体有较强的上升气流。雨滴谱资料的应用说明,降水过程中不同雨强下雨滴谱分布均呈单峰型,随着雨强增加,雨滴谱谱型在大粒子端逐渐上抬。对流云降水谱宽明显大于层状云降水。对流云降水阶段的平均直径明显大于层状云降水阶段。

Multi source data analysis of local strong convection in the late autumn of South of Jiangsu

Using radar, lightning locator, wind profiler radar and raindrop spectrometer respectively, a strong convective weather in South of Jiangsu in 2014 is analyzed in this paper, and these new detection data have been found with implications for the occurrence and development of strong convection. The weather process mainly results from obvious warming in the early stage, strong southwest air flow and cold air steered by upper level trough. The invasion of cold air leads to the happening of local strong convection. In late autumn, the various potentiality of strong convection is significantly different from the threshold of strong convection during the flood season. Although the unstable energy in late autumn is not strong as that in spring or summer, under the favorable dynamic condition, the lifting of warm humid air could be forced by low level cold air and then hail is triggered. The comparison of various indicators of radar data and strong convection during flood season indicates that: compared with the hail case in flood season, VIL and echo top height of the hail in Wuxi is significantly lower, and this is closely related to the difference of season. The thermal condition is not favorable as that in spring or summer and this leads to the low echo top. The statistics of lightning data show that: the sudden increase of lightning number indicates the existence of strong updraft in super-storm. The application of raindrop size distribution data shows that the distributions of raindrops in different rainfall intensity all show unimodal type. The raindrop spectrum gradually uplifts at the end of large particle as precipitation enhances. The spectral width of convective cloud precipitation is obviously larger than that of stratiform cloud precipitation. The average diameter during convective cloud precipitation is significantly larger than that during stratiform cloud precipitation.