一次高炮防雹的相控阵双偏振雷达观测特征北大核心CSCD

选取2021年6月28日山西省临汾市隰县一次高炮防雹作业过程,利用隰县X波段相控阵双偏振雷达数据分析作业前后强对流云变化的现象和机理。高炮防雹作业后冰雹云单体的宏观特征、动力和微物理的垂直结构均出现短时间明显变化。高炮防雹作业后1 min 55 dBZ顶高急剧下降约2 km至0℃层以下,水平反射率因子ZH的强回波垂直结构在0℃层断裂,径向速度散度显示单体前部和后部的辐合带减弱、消失,差分反射率ZDR在近地面增大,ZDR柱消失,差分相移率KDP在中低层增大,共极化相关系数ρ_(hv)从0℃层到近地面表现为0.94~0.96的柱状区,单体核心上部的过冷水小范围中心消失,0℃层以下由雨夹雹、霰、湿雪及各种雨的混合柱状分布转为低层大雨。这些短时间的明显变化现象支持爆炸防雹理论。

Features of Phased-array Dual Polarization Radar Observation During an Anti-aircraft Gun Hail Suppression Operation

Phased-array dual polarization weather radar has the capability on high spatial-temporal resolution detection and microphysical analysis, and it is deemed a new approach of strong convection monitoring and research. If applied in hail suppression operation, it is expected to improve the ability of operation command and effect evaluation. Hence, a case study is carried out on a hail suppression operation by anti-aircraft gun in Xi County, Linfen City, Shanxi Province on 28 June 2021. A phased array dual polarization weather radar is used, which outputs a volume scan data every minute consisting of 21 elevation levels. The radial resolution is 30 m, and the elevation resolution is 1.8°. Based on such high spatial-temporal resolution observations, the phenomenon and mechanisms of the severe convective cell before and after operation are analyzed, including the time series of reflectivity top height and the dynamic and microphysics features in the RHI(range height indicator) profiles. The top height of 55 dBZ reflectivity declines rapidly within 1 min after hail suppression operation, steeping down 2 km to below 0℃ height and maintains. After that, the top height of reflectivity has a short recovery due to the effect of cells merging, but then gradually decreases. 1 min after the operation, the vertical structure of high horizontal reflectivity (Z_H) is fractured near 0℃ layer. The parameter of radial velocity divergence (RVD) is proposed to diagnose the vertical airflow structure, showing that the convergence areas in the front and rear of the cell weaken or disappear. The differential reflectivity (Z_DR) increases near ground, and the specific phase shift (K_DP) increases in the middle and low layers. The Z_DR column disappears. There is a column of co-polar correlation coefficient (CC) with the value 0.94-0.96 from the near ground level to 0℃ layer. The small area of the supercooled water in the upper part of the cell core disappears. Below 0℃ layer, the mixed columnar distribution of rain and hail, graupel, wet snow and various rain changes to heavy rain in the low-level. Therefore, these short-term and obvious changes can support the theories of hail suppression by explosion.