Simulation of Cloud Microphysical and Chemical Processes Using a Multicomponent Framework. Part II: Microphysical Evolution of a Wintertime Orographic Cloud
Simulation of Cloud Microphysical and Chemical Processes Using a Multicomponent Framework. Part II: Microphysical Evolution of a Wintertime Orographic Cloud
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使用多组件框架模拟云微物理和化学过程。
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
D. Lamb
中科院分区：
文献类型：
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作者：
Jen‐Ping Chen;D. Lamb
用一个详细的微物理模式模拟了稳态条件下冬季地形云在二维域的形成。计算得到的液态云和冰相云粒子的质量含量和数浓度与观测结果吻合较好。云中的冰粒以及沉淀到地面的冰粒可分为小的云冰、平面晶体、柱状晶体、重边晶体和晶体聚集体。对结果的详细分析表明，接触成核和雾水碎裂是云层较暖部分的主要结冰机制，而高层则以沉积/凝结-冻结成核为主。地面降水，无论是以雨还是雪的形式，主要通过凝结和聚集来发展，去除了进入云的总水汽的17%以上。云粒子在多组分框架中的光谱分布不仅提供了关于粒子大小的信息，而且还提供了关于其溶质含量的信息，对于冰粒，还提供了其形状的信息。对这些多组分分布的研究揭示了颗粒形成和相互作用的机制，以及结晶习惯对环境条件的适应。另外还进行了模拟，以测试云和降水的形成对气溶胶粒子尺寸分布的敏感性。结果表明，气溶胶粒子的尺度分布不仅对暖云过程有显著影响，而且对冷云过程也有显著影响。气溶胶粒子浓度的降低不仅导致降水发展的提前，而且增加了地形云的总降雨量。
A detailed microphysical model is used to simulate the formation of wintertime orographic clouds in a twodimensional domain under steady-state conditions. Mass contents and number concentrations of both liquid- and ice-phase cloud particles are calculated to be in reasonable agreement with observations. The ice particles in the cloud, as well as those precipitated to the surface, are classified into small cloud ice, planar crystals, columnar crystals, heavily rimed crystals, and crystal aggregates. Detailed examination of the results reveals that contact nucleation and rime splintering are the major ice-production mechanisms functioning in the warmer part of the cloud, whereas deposition/condensation-freezing nucleation is dominant at the upper levels. Surface precipitation, either in the form of rain or snow, develops mainly through riming and aggregation, removing over 17% of the total water vapor that entered the cloud. The spectral distributions of cloud particles in a multicomponent framework provide information not only on particle sizes but also on their solute contents and, for ice particles, their shapes. Examination of these multicomponent distributions reveals the mechanisms of particle formation and interaction, as well as the adaptation of crystal habits to the ambient conditions. Additional simulations were done to test the sensitivity of cloud and precipitation formation to the size distribution of aerosol particles. It is found that the size distribution of aerosol particles has significant influence on not only the warm-cloud processes, but also the cold-cloud processes. A reduction in aerosol particle concentration not only causes an earlier precipitation development but also an increase in the amount of total precipitation from the orographic clouds.