The Balance Between Heterogeneous and Homogeneous Nucleation of Ice Clouds Using CAM5/CARMA
The Balance Between Heterogeneous and Homogeneous Nucleation of Ice Clouds Using CAM5/CARMA
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DOI：
10.1029/2021jd035540
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发表时间：
2022-02
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影响因子：
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通讯作者：
Christopher Maloney;B. Toon;C. Bardeen;P. Yu;K. Froyd;J. Kay;S. Woods
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作者：
Christopher Maloney;B. Toon;C. Bardeen;P. Yu;K. Froyd;J. Kay;S. Woods
我们对社区大气气溶胶和辐射模型（CARMA）截面冰微物理模型进行了修改，在其中我们添加了硫酸盐的相互作用成核和非均质成核到尘埃中，以便在CARMA截面冰模型中创建更全面的冰成核表示。Yu等人（2019,https://doi.org/10.1029/2018gl080544）还添加了对流湿去除修复，以便在社区大气模型第5版（CAM5）和3模态气溶胶模型（MAM3）中正确传输气溶胶。在CARMA中，均相和非均相成核的平衡是由低于240 K的温度、过饱和和非均相核的可用性控制的。在我们的模拟中，由于在海拔约7公里以上的地方尘埃较少，而地球大部分地区的温度低于240 K，因此在海拔7公里以上的卷云主要通过均匀的硫酸盐气溶胶成核。在北半球中纬度地区，春季到秋季7公里以上的沙尘更为常见，在我们的模型中，非均质成核和均质冻结都发生了。在7公里以下，冰的原位形成主要以非均质成核为主。此外，我们发现在CAM5/CARMA中，混合相云中冰的表现与只有均匀冰核的模拟相比有所改善。其他的成核模式，如液云滴的接触成核或液云滴在浸入核上的冻结，在本研究中没有直接与经典的沉积非均质成核进行比较。
We present a modification to the Community Aerosol and Radiation model for Atmospheres (CARMA) sectional ice microphysical model where we have added interactive nucleation of sulfates and heterogeneous nucleation onto dust in order to create a more comprehensive representation of ice nucleation within the CARMA sectional ice model. The Yu et al. (2019, https://doi.org/10.1029/2018gl080544) convective wet removal fix has also been added in order to correctly transport aerosol within the Community Atmosphere Model version 5 (CAM5) and the 3‐mode Modal Aerosols Model (MAM3). In CARMA, the balance of homogeneous and heterogeneous nucleation is controlled by the presence of temperatures below 240 K, supersaturation, and the availability of heterogeneous nuclei. Due to a paucity of dust at altitudes above about 7 km, where temperatures over most of the Earth fall below 240 K, cirrus clouds above 7 km nucleate primarily via homogeneous nucleation on aqueous sulfate aerosols in our simulations. Over mid‐latitudes of the Northern Hemisphere, dust is more common above 7 km during spring through fall, and both heterogeneous nucleation and homogenous freezing occur in our model. Below 7 km heterogeneous nucleation dominates in situ formation of ice. Furthermore, we find an improvement of the representation of in‐cloud ice within mixed phase clouds in CAM5/CARMA when compared to simulations with only homogeneous ice nucleation. Other modes of nucleation such as contact nucleation of liquid cloud droplets or liquid cloud droplet freezing on immersion nuclei, were not directly compared with classical depositional heterogeneous nucleation in this study.