【摘要】 基于垂直液态水含量（VIL）、最大水平反射率因子（DBZM）、质心高度（HT）等S波段双偏振天气雷达资料，对2025年3月2日湘西一次超大冰雹超级单体演变特征进行分析。结果表明：（1）中气旋的厚度、最强切变及高度对降雹时间、风暴消亡有一定指示作用；最强切变高度骤降，地面降雹；最强切变高度降至低层且厚度减小，超级单体减弱；最强切变高度骤升且切变小，中气旋趋于消亡。（2）超级单体在垂直结构上表现出低层气旋性辐合、中层双涡旋、高层辐散特征，这种垂直结构有利于雹胚增长；中层的双涡旋结构使得超级单体生命史较长，并影响其移动方向。（3）不同阶段差分反射率因子(Z_DR)、相关系数（CC）、差分相移率(K_DP)特征有明显差异，成熟降雹阶段，强回波中心（水平反射率因子≥65 dBz,最大72 dBz）高度降至4 km以下且底部接地，对应CC为0.65～0.8,Z_DR值接近于0,低层K_DP空洞。更多还原

【Abstract】 Based on S-band dual-polarisation weather radar data, this study conducts a comprehensive analysis of the evolutionary characteristics of the supercell that produced extremely large hail in western Hunan on 2 March 2025. This severe weather event developed under the influence of low-level warm advection, with strong thermal instability, intense vertical wind shear, and an optimal wet-bulb zero-degree level height collectively providing highly favourable conditions for the formation and maintenance of this large hail-producing supercell. Utilising key radar parameters including Vertical Integrated Liquid water content, maximum horizontal reflectivity, and centroid height, the storm’s evolution was categorised into four distinct phases: initial development, coalescence growth, mature hail-falling, and weakening dissipation. The results demonstrate that:(1) Mesocyclone thickness, the magnitude of the strongest rotational shear, and its corresponding altitude served as valuable indicators for predicting hail onset and subsequent storm decay. A precipitous descent in the altitude of the peak shear directly preceded surface hailfall; a subsequent lowering of this peak shear height to near-surface levels, coupled with a reduction in mesocyclone thickness, signalled supercell weakening; whereas a rapid elevation of the peak shear height accompanied by diminished shear intensity denoted the imminent dissipation of the mesocyclone.(2) The supercell demonstrated a characteristic vertical vorticity structure, comprising low-level cyclonic convergence, a mid-level dual-vortex configuration featuring both cyclonic and anticyclonic circulations, and upper-level divergence. This organised vertical architecture was highly conducive to hail embryo development and growth. Furthermore, the persistent mid-level dual-vortex structure was identified as a key factor prolonging the supercell’s lifespan and exerting a discernible influence on its propagation trajectory.(3) Distinct temporal variations in dual-polarisation parameters including differential reflectivity, correlation coefficient, and specific differential phase were observed across different evolutionary stages. During initial development dominated by vertical growth, the ZDR column core exceeding 2.5 dB progressively ascended above the-20 ℃ level, with graupel and frozen raindrops above the 0 ℃ level serving as primary hail embryos. The coalescence growth stage featured dramatic storm intensification with the ZDR column core descending to 3.5 km and below, accompanied by ZDR values approaching 0 dB around 5 km altitude, distinct KDP holes, and correlation coefficients decreasing below 0.9, all representing characteristic signatures of large hail formation. Throughout the mature hail-production stage, the intense reflectivity core reaching ≥ 65 dBz with maximum values of 72 dBz subsided below 4 km with its base contacting the surface, corresponding to correlation coefficients of 0.65-0.8, near-zero ZDR values, and a well-defined KDP hole in lower storm levels.更多还原