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DOI	10.1073/pnas.1921231117
	Aerosols enhance cloud lifetime and brightness along the stratus-to-cumulus transition
	Christensen M.W.; Jones W.K.; Stier P.
发表日期	2020
ISSN	0027-8424
起始页码	17591
结束页码	17598
卷号	117 期号:30
英文摘要	Anthropogenic aerosols are hypothesized to enhance planetary albedo and offset some of the warming due to the buildup of greenhouse gases in Earth’s atmosphere. Aerosols can enhance the coverage, reflectance, and lifetime of warm low-level clouds. However, the relationship between cloud lifetime and aerosol concentration has been challenging to measure from polar orbiting satellites. We estimate two timescales relating to the formation and persistence of low-level clouds over 1◦ × 1◦ spatial domains using multiple years of geostationary satellite observations provided by the Clouds and Earth’s Radiant Energy System (CERES) Synoptic (SYN) product. Lagrangian trajectories spanning several days along the classic stratus-to-cumulus transition zone are stratified by aerosol optical depth and meteorology. Clouds forming in relatively polluted trajectories tend to have lighter precipitation rates, longer average lifetime, and higher cloud albedo and cloud fraction compared with unpolluted trajectories. While liquid water path differences are found to be negligible, we find direct evidence of increased planetary albedo primarily through increased drop concentration (Nd) and cloud fraction, with the caveat that the aerosol influence on cloud fraction is positive only for stable atmospheric conditions. While the increase in cloud fraction can be large typically in the beginning of trajectories, the Twomey effect accounts for the bulk (roughly 3/4) of the total aerosol indirect radiative forcing estimate. © 2020 National Academy of Sciences. All rights reserved.
英文关键词	Aerosols; Clouds; Radiative forcing
语种	英语
scopus关键词	albedo; Article; atmosphere; brightness; climate change; cloud; cloud lifetime; controlled study; environmental temperature; precipitation; priority journal; seasonal variation; stratus to cumulus transition; weather
来源期刊	Proceedings of the National Academy of Sciences of the United States of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/160252
作者单位	Christensen, M.W., Atmospheric, Oceanic and Planetary Physics, University of Oxford, Oxford, OX1 3PU, United Kingdom; Jones, W.K., Atmospheric, Oceanic and Planetary Physics, University of Oxford, Oxford, OX1 3PU, United Kingdom; Stier, P., Atmospheric, Oceanic and Planetary Physics, University of Oxford, Oxford, OX1 3PU, United Kingdom
推荐引用方式 GB/T 7714	Christensen M.W.,Jones W.K.,Stier P.. Aerosols enhance cloud lifetime and brightness along the stratus-to-cumulus transition[J],2020,117(30).
APA	Christensen M.W.,Jones W.K.,&Stier P..(2020).Aerosols enhance cloud lifetime and brightness along the stratus-to-cumulus transition.Proceedings of the National Academy of Sciences of the United States of America,117(30).
MLA	Christensen M.W.,et al."Aerosols enhance cloud lifetime and brightness along the stratus-to-cumulus transition".Proceedings of the National Academy of Sciences of the United States of America 117.30(2020).