Cloud Top Radiative Cooling Rate Drives Non‐Precipitating Stratiform Cloud Responses to Aerosol Concentration
Cloud Top Radiative Cooling Rate Drives Non‐Precipitating Stratiform Cloud Responses to Aerosol Concentration
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DOI：
10.1029/2021gl094740
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发表时间：
2021-09
影响因子：
5.2
通讯作者：
Abigail Williams;A. Igel
中科院分区：
文献类型：
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作者：
Abigail Williams;A. Igel
众所周知，气溶胶浓度的增加会影响云的微物理过程和辐射特性。通过减小液滴尺寸，气溶胶的增加可以降低碰撞效率并增加降水云中的液态水路径（LWP），或者提高蒸发率并降低非降水云中的LWP。我们利用大涡模拟进一步研究了这些气溶胶在北极混合相云中的间接影响，并发现，与以前的研究一致，降水云的LWP增加，非降水云的LWP减少。然而，最重要的是，我们的结果揭示了一个不同的解释，为什么这样的LWP减少发生在解耦，非降水云。我们发现云顶附近的蒸发增强主要是由气溶胶浓度驱动的最大辐射冷却速率的加强，从而驱动更强的夹带，即使在光学厚的云中也是如此。
Increases in aerosol concentration are well known to influence the microphysical processes and radiative properties of clouds. By reducing droplet size, an increase in aerosol can lessen collision efficiency and increase liquid water path (LWP) in precipitating clouds or enhance evaporation rate and decrease LWP in non‐precipitating clouds. We utilize large eddy simulations to further investigate these aerosol indirect effects in Arctic mixed‐phase clouds and find, in agreement with previous studies, precipitating clouds to experience an increase in LWP and non‐precipitating clouds a decrease in LWP. Most importantly however, our results reveal a different explanation for why such an LWP decrease occurs in decoupled, non‐precipitating clouds. We find enhanced evaporation near cloud top to be driven primarily by a strengthening of maximum radiative cooling rate with aerosol concentration which drives stronger entrainment, an effect that holds true even in clouds that are optically thick.