威宁一次单体雹暴防雹作业的宏微观物理响应特征分析

Analysis of Macro and Micro Physical Response Characteristics of a Hail-suppression Operation Against an Unicellular Hailstorm in Weining

为研究单体雹暴作业后雹云宏、微观物理演变特征,利用威宁雪山镇X波段雷达数据和水成物粒子识别方法,并根据催化剂的扩散模式,将雹云演变分区域和时段进行对比分析。结果表明,作业前雹云冰雹形成区水平反射率为45~55 dBZ,差分反射率在-0.5~3.5 dB,差分传播相移率小于0.5°/km,相关系数在0.60~0.92。冰雹形成区主要为雨雹混合物,雹粒子周围围绕着高密度霰和过冷水。作业后,雹云反射率的减小和强回波高度的降低主要发生在播撒时段,回波顶高和风暴高度的降低主要发生在后续时段。作业区中雹粒子、过冷水明显减少,聚合物和冰晶增多,高密度霰变化不明显。单体雹云雹胚来源主要为高密度霰,其防雹效应主要遵循的理论为“利益竞争”和“早期降雨”。

This study analyzed the macro and micro physical response characteristics of a unicellular hailstorm after seeding using X-band dual-polarization radar data and an X-pol hydrometeor identification(HID)algorithm.According to the dif-fusion of the seeding agents,a comparative analysis was conducted on the evolution of the seeded hailstorm in different re-gions and periods.The results are as follows:Before seeding,the polarization characteristics of the hail-forming region(45 dBZ≤ZH≤55 dBZ,-0.5 dB≤ZDR≤3.5 dB,KDP≤0.5°/km,0.60≤ρHV≤0.92)suggesting that this region was mainly composed of rain-hail mixture.The hailstones are surrounded by high-density graupel and abundant supercooled wa-ter.After seeding,the decrease in the reflectivity and the height of strong echo mainly occurred in the seeded period,while the decrease in the echo top and the height of the storm was mainly in the post-seeded period.In the seeded region,hail-stones and supercooled water decreased significantly,aggregates and ice crystals increased,and high-density graupel did not change obviously.For hailstorms with a high content of supercooled droplets and the main hail embryo materials is high-density graupel,the key mechanisms of hail suppression are“beneficial competition”and“early rainout”.