云南多普勒天气雷达网探测冰雹的覆盖能力

冰雹是常见的天气现象之一，天气雷达是探测冰雹的一种强有力工具。多普勒天气雷达网除体扫模式的局限外，复杂的山地地形对雷达波束造成的遮挡，对于雷达探测冰雹天气现象的不利影响非常大。针对雹云回波的垂直结构特征，考虑0℃、-20℃层高度和回波强中心高度几个关键参数，分析雷达探测雹云的区域覆盖能力。以位于低纬度高原的云南省C波段多普勒天气雷达网为对象，分析其探测雹云的覆盖情况，并按探测效果进行了区域分型。与实际降雹天气的对比表明，该评估方法衡量雹云探测范围较合理；云南多普勒天气雷达网雹云适合探测区约占全省面积的75%，约2%的面积部分遮挡，0.2%被完全遮挡，遮挡比较严重的区域主要位于昭通东北部和临沧东北部。云南省规划的9部雷达全部业务化运行后，理论上90%的地面降雹区能被雷达有效监测和识别，约有3%的地面冰雹区只有当雹云发展到8 km以上才能被识别，约6%只能探测8 km高度以下的回波，可能导致漏判、误判，约8.5%面积为冰雹识别的盲区。

Coverage Capacity of Hail Detection for Yunnan Doppler Weather Radar Network

Weather radar is a powerful tool for hail detecting, but the detection ability of Doppler weather radar network is influenced not only by weather radar volume coverage pattern (VCP) strategy, but also radar beam blockage due to the complex terrain in mountainous areas. Hail storm cells emerge on the low-level area far from the radar and near the cone of silence is often underestimated. In addition, meteorological scatter objects are distorted at less terrain blockage areas or even can't be detected completely at severe blockage area. Radar beam blockage by various terrain shape in mountainous region is very common, resulting in some of storm cells difficult to identify by weather radar network. Therefore, an assessment method of hail observation ability for Doppler weather radar network is proposed, based on the average height of 0℃, -20℃ level and the height of the core of storm cells. The multiple layer grid data of three-dimensional coverage for Yunnan C-band Doppler weather radar network is built up by combining the radar beam hybrid scanning method with the high-resolution Shuttle Radar Topography Mission (STRM) terrain data. According to characteristics of the hail cell stretching level, the coverage scope above 0℃ level of weather radar network is considered as an assessment method to evaluate hail detecting capabilities of weather radar network. Based on C band Doppler weather radar network in Yunnan Province, 607 hail ground report samples are collected during 2014-2016 to analyze capabilities and limitations of hail detection in the low-latitude plateau, and the detection area classification is summed up. Results show that it is reasonable for judging effects of the hailstorm detection with the height of 0℃ level and several height differences. The suitable detecting area account for roughly 75% throughout the province. Areas located in the northeast part of Zhaotong prefecture and the northeast part of Lincang prefecture are evaluated as hail detecting disadvantaged zone because of severe terrain blockage. Theoretically, with weather radars, based on the hailstorm probability during 2014-2016, over 90% hailstorm in Yunnan can be monitored and recognized effectively. About 3% hailstorm cell can be recognized when higher than 8 km, and about 6% hailstorm falls around radars that only cover below 8 km, and these may cause underestimation. 8.5% area of Yunnan is still beyond coverage, and 9 radars will be put into operational observation network. The proposed method can be used for assessing the ability of hailstorm detecting with the Doppler weather radar network quantitatively.