Aerosol-Cloud-Precipitation Interactions in a Closed-cell and Non-homogenous MBL Stratocumulus Cloud
Aerosol-Cloud-Precipitation Interactions in a Closed-cell and Non-homogenous MBL Stratocumulus Cloud
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DOI：
10.1007/s00376-022-2013-6
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发表时间：
2022-09
影响因子：
5.8
通讯作者：
Xiaojian Zheng;Xiquan Dong;D. Ward;B. Xi;Peng Wu;Yuanzu Wang
中科院分区：
文献类型：
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作者：
Xiaojian Zheng;Xiquan Dong;D. Ward;B. Xi;Peng Wu;Yuanzu Wang
选取了北大西洋东部气溶胶和云实验(ACE-ENA)飞机外场活动期间的一个闭合单元海洋层积云个例，考察了云和细雨微物理性质的非均质性以及气溶胶-云-降水的相互作用。与云传播平行和垂直的两组飞行支腿LEG-1和LEG-2分别具有云和毛毛雨微物理的空间和垂直变异性。LEG-2云层接近绝热，云滴有效半径和液态水含量从云底到云顶呈线性增加，且毛毛雨较少。LEG-1云系为亚绝热云团，云滴数密度较小，有效云滴数较大，但毛毛雨滴数密度较大，雨滴中值直径和毛雨液态水含量较大。由于强烈的湍流，云内的碰撞-合并过程增强了LEG-1上较大的毛毛雨频率和强度。LEG-1的亚云降水速率显著高于LEG-2沿线。结果表明，LEG-1上的次云累积模式气溶胶和CCN减少，而粗模式气溶胶增加。这进一步导致了一个与直觉相反的现象，即对于LEG-1，CCN小于云滴数浓度。平均CCN损失率分别为−3.89 cm−3h−1和−0.77 cm−3h−1。同一层积云内的云雾和细雨不均匀可以显著改变次云气溶胶和CCN的预算。因此，在飞机评估气溶胶-云-降水相互作用时应谨慎对待。
A closed-cell marine stratocumulus case during the Aerosol and Cloud Experiments in the Eastern North Atlantic (ACE-ENA) aircraft field campaign is selected to examine the heterogeneities of cloud and drizzle microphysical properties and the aerosol-cloud-precipitation interactions. The spatial and vertical variabilities of cloud and drizzle microphysics are found in two different sets of flight legs: Leg-1 and Leg-2, which are parallel and perpendicular to the cloud propagation, respectively. The cloud along Leg-2 was close to adiabatic, where cloud-droplet effective radius and liquid water content linearly increase from cloud base to cloud top with less drizzle. The cloud along Leg-1 was sub-adiabatic with lower cloud-droplet number concentration and larger cloud-droplet effective, but higher drizzle droplet number concentration, larger drizzle droplet median diameter and drizzle liquid water content. The heavier drizzle frequency and intensity on Leg-1 were enhanced by the collision-coalescence processes within cloud due to strong turbulence. The sub-cloud precipitation rate on Leg-1 was significantly higher than that along Leg-2. As a result, the sub-cloud accumulation mode aerosols and CCN on Leg-1 were depleted, but the coarse model aerosols increased. This further leads to a counter-intuitive phenomenon that the CCN is less than cloud-droplet number concentration for Leg-1. The average CCN loss rates are −3.89 cm−3h−1and −0.77 cm−3h−1on Leg-1 and Leg-2, respectively. The cloud and drizzle heterogeneities inside the same stratocumulus can significantly alter the sub-cloud aerosols and CCN budget. Hence it should be treated with caution in the aircraft assessment of aerosol-cloud-precipitation interactions.