Black carbon semi-direct effects on cloud cover: review and synthesis
Black carbon semi-direct effects on cloud cover: review and synthesis
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DOI：
10.5194/acp-10-7685-2010
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发表时间：
2010-01-01
影响因子：
6.3
通讯作者：
Del Genio, A. D.
中科院分区：
文献类型：
--
作者：
Koch, D.;Del Genio, A. D.
吸收性气溶胶（AAs），如黑碳（BC）或尘埃，吸收入射的太阳辐射，扰乱大气的温度结构，并影响云层覆盖。以前的研究已经描述了AAs增加或减少云量的条件。这种影响取决于几个因素，包括AA相对于云的高度和云的类型。我们试图将这些影响分为几种可能的情况。如果AAs嵌入在云层中，云量就会减少。云下的AAs可增强对流和云量。云顶上方的AAs稳定下层，倾向于增强层积云，但可能会减少积云。AAs还可以促进辐合区域的云量，因为它们增强了深层对流和低层辐合，从而将水分从海洋吸引到陆地区域。大多数全球模式研究表明，云响应存在区域差异，但总体上海洋和一些陆地区域的云覆盖增加，低层云覆盖净增加和/或上层云覆盖减少。其结果是从云响应到AAs的净负半直接效应反馈。在一些气候模式研究中，由于云的变化，BC的冷却效应强到足以从根本上抵消变暖的直接影响。
Absorbing aerosols (AAs) such as black carbon (BC) or dust absorb incoming solar radiation, perturb the temperature structure of the atmosphere, and influence cloud cover. Previous studies have described conditions under which AAs either increase or decrease cloud cover. The effect depends on several factors, including the altitude of the AA relative to the cloud and the cloud type. We attempt to categorize the effects into several likely regimes. Cloud cover is decreased if the AAs are embedded in the cloud layer. AAs below cloud may enhance convection and cloud cover. AAs above cloud top stabilize the underlying layer and tend to enhance stratocumulus clouds but may reduce cumulus clouds. AAs can also promote cloud cover in convergent regions as they enhance deep convection and low level convergence as it draws in moisture from ocean to land regions. Most global model studies indicate a regional variation in the cloud response but generally increased cloud cover over oceans and some land regions, with net increased low-level and/or reduced upper level cloud cover. The result is a net negative semi-direct effect feedback from the cloud response to AAs. In some of these climate model studies, the cooling effect of BC due to cloud changes is strong enough to essentially cancel the warming direct effects.