摘要:冰雹形成的微物理机理是人工防雹的重要科学依据，但对我国西南地区冰雹形成的微物理机理研究很少。利用中国科学院大气物理研究所三维冰雹分档云模式对云南2016年7月11日一次冰雹云过程进行了数值模拟研究，揭示了冰雹形成的微物理机理。此次冰雹云生成发展快，强度大，是西南山区典型夏季冰雹云。数值模拟的降水、降雹和回波强度等物理量与对应的观测量基本一致。模拟的冰雹云的最大上升气流速度达到28.7 m s?1。通过对冰雹形成的微物理过程分析研究表明，雹/霰胚的主要生成来源是通过过冷雨滴的概率冻结产生的冻滴，占95%，而冰晶碰冻雨滴产生的雹/霰胚仅占5%，这与国外和我国其他地区雹/霰胚产生的来源和冻滴所占比例有明显差别；形成的雹/霰胚直径多数集中在0.3 mm至3.0 mm范围，雹/霰胚主要通过对过冷云水的碰并过程实现增长，直径小于0.3 mm的雹/霰胚较难增长；大雨滴冻结成较大直径的雹胚，可促成短时间内形成冰雹；在雹云发展过程中存在短时的过冷雨水累积带，但过冷雨水累积带对雹/霰胚的增长贡献不大。
关键词:冰雹形成/
冰雹分档模式/
过冷雨水累积带/
云南
Abstract:The microphysical formation mechanism of hailstones is the scientific basis of hail suppression operation. However, the relevant study on this issue in southwestern China is few. A hailstorm case on July 11, 2016, in Yunnan is numerically simulated using the three-dimensional cloud model with hail-bin microphysics developed by the Institute of Atmospheric Physics, Chinese Academy of Sciences, and the microphysical formation mechanism of the hailstorm is investigated. The hail cloud developed rapidly with high intensity and is a typical summer hail cloud in the southwest mountainous region. The simulated physical parameters such as rainfall, hailfall, and reflectivity are generally consistent with those observed. The simulated maximum updraft is 28.5 m/s. The microphysical processes of the hailstorm indicate that the main source of hail/graupel embryos is produced by the probability freezing process of supercooled raindrops, which is accounted for 95%, whereas the source via the collision between ice crystals and supercooled raindrops is only accounted for 5%, which are significantly different from other regions in both China and other countries. The diameters of hail/graupel embryos mainly range from 0.3–3.0 mm. The growth of hail/graupel embryos depends on the collision process with the supercooled cloud water, in which the embryos with a diameter less than 0.3 mm are hard to grow. Larger raindrops can directly freeze into larger hail embryos, which can contribute to the formation of hailstones in a short period. A short-lasting accumulation zone of supercooled rainwater occurs in the development process of the hail cloud, and it has little contribution to the growth of hail/graupel embryos.
Key words:Hailstone formation/
Cloud model with hail-bin microphysics/
Supercooled rainwater accumulation zone/
Yunnan Province
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