利用山西4部C波段多普勒天气雷达基数据和地面观测资料， 对2009 -2017年山西出现的38次多普勒雷达V型缺口特征进行统计分析， 研究多普勒雷达V型缺口特征与降雹的对应关系， 总结V型缺口对冰雹的预报预警指标， 并在2018 -2022年开展实时业务应用， 对V型缺口特征及预报预警指标进行检验并订正。结果表明： 降雹在V型缺口出现后开始， 在V型缺口消失前结束； 降雹概率与V型缺口起始高度无明显的对应关系； V型缺口对应的上升气流高度≤4 km时无降雹； V型缺口理想的观测仰角为2.4°~6.0°， 最佳观测仰角为2.4°； 强回波区呈现“蝴蝶状”是降雹最强阶段。降雹开始阶段预报预警指标及关注点： （1）V型缺口有弱回波区或有界弱回波区； （2）初始V型缺口沿径向长度>30 km， 当≤30 km时上升气流伸展高度要超过4 km； （3）平均径向速度具有低层辐合高层辐散特征。满足以上3点可预报有冰雹出现， 如果V型缺口首先在6.0°仰角观测到， 可预报有大冰雹出现（直径大于1 cm）， 并立即发布预报预警信号。冰雹持续期间预报预警指标及关注点： （1）>50 dBZ强回波中心连续下降且回波顶高>10 km； （2）V型缺口对应的弱回波区呈倾斜状； （3）弱回波区或有界弱回波区稳定维持； （4）当在0.5°仰角观测到V型缺口时可预报冰雹仍在持续； 当强回波区呈现“蝴蝶状”， 可预报降雹强度增强； （5）当V型缺口最大垂直液态水含量>22 kg·m^-2、 垂直液态水含量跃增量>26 kg·m^-2、 垂直液态水含量密度>3.6 g·m^-3时， 出现冰雹的概率较大。

Using the basic data from four C-band Doppler weather radars and ground observation data in Shanxi province， the statistical analysis of the V-shaped gap features observed in Shanxi from 2009 to 2017 was conducted.The correspondence between V-shaped gap observed by Doppler radar and hailfall was investigated， and the forecasting and warning indicators for hail using V-shaped gap features were summarized.Real-time operational applications were carried out from 2018 to 2022 to validate and refine forecasting and warning indicators of the V-shaped gap.The results indicate that hailfall begins after the appearance of V-shaped gap and ends before their disappearance.There is no significant correlation between the probability of hailfall and the initial height of V-shaped gap.When the corresponding updraft height of V-shaped gap is ≤4 km， hailfall does not occur.The ideal observation elevation angle for V-shaped gap ranges from 2.4°to 6.0°， with 2.4°being the optimal angle.The strongest phase of hailfall is characterized by a "butterfly-shaped" intense echo region.The predictive indicators and focal points during the initial stage of hail forecasting and early warning include： （1） the presence of a weak or marginally weak echo region when a V-shaped gap appears； （2） a length of the V-shaped gap along the radial direction > 30 km， or an initial length of the V-shaped gap along the radial direction <30 km and an updraft extending above 4 km； （3） average radial velocity showing low-level convergence and high-level divergence characteristics.Meeting these three criteria can predict the occurrence of hail.If a V-shaped gap is first observed at a 6.0° angle， a forecast can be made for the occurrence of large hailstones （with a diameter greater than 1 cm）， and an immediate forecasting and warning signal can be issued.The predictive indicators and focal points during the duration of hail include： （1） continuous decrease in the height of the strong echo center > 50 dBZ and echo top > 10 km； （2） a slanted weak echo region corresponding to the V-shaped gap， with high-level divergence and low-level convergence characteristics in the average radial velocity field； （3） stable maintenance of the weak echo region or marginally weak echo region； （4） continuous occurrence of hail can be predicted when the V-shaped gap is observed at a 0.5° angle， and an increase in hail intensity can be foreseen when the strong echo region exhibits a "butterfly" shape； （5） When the maximum vertical liquid water content exceeds 22 kg·m^-2， the vertical liquid water content jump increment exceeds 26 kg·m^-2， and the vertical liquid water content density exceeds 3.6 g·m^-3， the probability of hail is high.