A bin microphysics parcel model investigation of secondary ice formation in an idealised shallow convective cloud
A bin microphysics parcel model investigation of secondary ice formation in an idealised shallow convective cloud
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DOI：
10.5194/acp-23-9099-2023
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发表时间：
2023-08
影响因子：
6.3
通讯作者：
R. James;J. Crosier;P. Connolly
中科院分区：
文献类型：
--
作者：
R. James;J. Crosier;P. Connolly
抽象的。我们提供了第一个系统的研究冰的形成在理想化的浅云从碰撞过冷水滴与冰粒（模式2）。使用曼彻斯特大学bin微物理学包裹模型，我们研究了由于模式2的冰形成的敏感性，广泛的参数，包括气溶胶颗粒尺寸分布，上升气流速度，云底温度，云深度，冰成核颗粒浓度，和模式2的冻结分数。我们提供的背景下，我们的结果与其他二次冰生产机制作为单一的机制和组合（雾凇分裂，球形冻结碎片的下降（模式1），冰-冰碰撞）。当上升气流速度较低（0.5 m s−1）时，对气溶胶颗粒尺寸分布有显著的敏感性;当气溶胶颗粒尺寸分布模拟污染环境时，不会发生二次结冰。在模拟云中确实发生了二次结冰的情况下，在较浅的云层（1.3公里深）中大量结冰是由于模式2或包括模式2在内的一种组合。较深的云（2.4公里深）也有显着的贡献，雾凇分裂或冰-冰碰撞破裂二次制冰（SIP）机制。虽然云底温度为7摄氏度的模拟对冰成核粒子浓度相对不敏感，但云底温度为0摄氏度的模拟却很敏感。增加成冰颗粒浓度可以延缓结冰。我们的研究结果表明，碰撞过冷水滴与冰粒可能是一个显着的冰形成机制在浅对流云雾凇分裂是不活跃的。
Abstract. We provide the first systematic study of ice formation in idealised shallow clouds from collisions of supercooled water drops with ice particles (mode 2). Using the University of Manchester bin microphysics parcel model, we investigated the sensitivity of ice formation due to mode 2 for a wide range of parameters, including aerosol particle size distribution, updraft speed, cloud-base temperature, cloud depth, ice-nucleating particle concentration, and freezing fraction of mode 2. We provide context to our results with other secondary ice production mechanisms as single mechanisms and combinations (rime splintering, spherical freezing fragmentation of drops (mode 1), and ice–ice collisions). There was a significant sensitivity to aerosol particle size distribution when updraft speeds were low (0.5 m s−1); secondary ice formation did not occur when the aerosol particle size distribution mimicked polluted environments. Where secondary ice formation did occur in simulated clouds, significant ice formation in the shallower clouds (1.3 km deep) was due to mode 2 or a combination which included mode 2. The deeper clouds (2.4 km deep) also had significant contributions from rime splintering or ice–ice collisional breakup secondary ice production (SIP) mechanisms. While simulations with cloud-base temperatures of 7 ∘C were relatively insensitive to ice-nucleating particle concentrations, there was a sensitivity in simulations with cloud-base temperatures of 0 ∘C. Increasing the ice-nucleating particle concentration delayed ice formation. Our results suggest that collisions of supercooled water drops with ice particles may be a significant ice formation mechanism within shallow convective clouds where rime splintering is not active.