Graupel Precipitating From Thin Arctic Clouds With Liquid Water Paths Less Than 50 g m −2
Graupel Precipitating From Thin Arctic Clouds With Liquid Water Paths Less Than 50 g m −2
复制标题
霰从薄薄的北极云层中析出，液态水路径小于 50 克/米 — 2
DOI：
10.1029/2021gl094075
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发表时间：
2021
影响因子：
5.2
通讯作者：
Garrett, Timothy J.
中科院分区：
文献类型：
--
作者：
Fitch, Kyle E.;Garrett, Timothy J.
边缘降水的增长可以有效地去除边界层中的水分和气溶胶，但薄的低层北极混合相云通常被认为会沉淀出原始的和聚集的冰晶。我们给出的地面自动摄影测量结果显示，只有34%的降水粒子表现出可以忽略不计的雾化，而直径较大的砾石粒子通常来自液态水路径小于50微克/米−2的云层。分析表明，如果S−1的上升气流持续上升0.4微米，就可以发生显著的雾化增强，这与在北极云中测得的结果一致。追踪下落粒子的拉格朗日数值模拟表明，类似的上升气流速度可以解释观察到的边缘增强的大约一半。当在云顶观测到微弱的逆温时，沸腾增强的可能性特别大，但完整的解释仍有待确定。
Rimed precipitation growth can efficiently remove moisture and aerosols from the boundary layer, yet thin low‐level Arctic mixed‐phase clouds are generally thought to precipitate pristine and aggregated ice crystals. Here we present automated surface photographic measurements showing that only 34% of precipitation particles exhibit negligible riming and that graupel particles in diameter commonly fall from clouds with liquid water paths less than 50 g m−2. Analyses indicate that significant riming enhancement can occur provided sustained updrafts of 0.4 m s−1, consistent with those measured in Arctic clouds. A Lagrangian numerical simulation that tracks falling particles suggests that similar updraft speeds can account for about one half of the observed riming enhancement. Riming enhancement appears particularly likely when weak temperature inversions are observed at cloud top, but a full explanation remains to be determined.