气候变化领域集成服务门户(CCPortal): Observationally constrained aerosol

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DOI	10.1038/s41612-019-0073-9
	Observationally constrained aerosol–cloud semi-direct effects
	Allen R.J.; Amiri-Farahani A.; Lamarque J.-F.; Smith C.; Shindell D.; Hassan T.; Chung C.E.
发表日期	2019
ISSN	23973722
卷号	2 期号:1
英文摘要	Absorbing aerosols, like black carbon (BC), give rise to rapid adjustments, and the associated perturbation to the atmospheric temperature structure alters the cloud distribution. The level of scientific understanding of these rapid cloud adjustments—otherwise known as semi-direct effects (SDEs)—is considered low, with models indicating a likely negative (−0.44 to +0.1 Wm−2) forcing. Recent studies suggest this negative SDE is primarily driven by decreases in high-level clouds and enhanced longwave cooling. Here, we investigate the SDE using multiple models driven by observationally constrained fine-mode aerosol forcing without dust and sea salt. Unlike aerosol simulations, which yield a relatively vertically uniform aerosol atmospheric heating profile with significant upper-tropospheric heating, observation-based heating peaks in the lower-troposphere and then decays to zero in the mid-troposphere. We find a significant global annual mean decrease in low- and mid-level clouds, and weaker decreases in high-level clouds, which leads to a positive SDE dominated by shortwave radiation. Thus, in contrast to most studies, we find a robust positive SDE, implying cloud adjustments act to warm the climate system. Sensitivity tests with identical average, but vertically uniform observationally constrained aerosol atmospheric heating result in a negative SDE, due to enhanced longwave cooling as a result of large reductions in high-level clouds. Our results therefore suggest that model simulations lead to a negatively biased SDE, due to an aerosol atmospheric heating profile that is too vertically uniform. © 2019, The Author(s).
语种	英语
scopus关键词	aerosol; air temperature; black carbon; climate forcing; cloud microphysics; computer simulation; heating; numerical model; sea salt; shortwave radiation; troposphere
来源期刊	npj Climate and Atmospheric Science
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/178110
作者单位	Department of Earth Sciences, University of California Riverside, Riverside, CA 92521, United States; NCAR/UCAR, Boulder, CO, United States; Priestley International Centre for Climate, University of Leeds, Leeds, LS2 9JT, United Kingdom; Earth and Ocean Sciences Division, Duke University, Durham, NC, United States; Division of Atmospheric Science, Desert Research Institute, Reno, NV 89512, United States
推荐引用方式 GB/T 7714	Allen R.J.,Amiri-Farahani A.,Lamarque J.-F.,等. Observationally constrained aerosol–cloud semi-direct effects[J],2019,2(1).
APA	Allen R.J..,Amiri-Farahani A..,Lamarque J.-F..,Smith C..,Shindell D..,...&Chung C.E..(2019).Observationally constrained aerosol–cloud semi-direct effects.npj Climate and Atmospheric Science,2(1).
MLA	Allen R.J.,et al."Observationally constrained aerosol–cloud semi-direct effects".npj Climate and Atmospheric Science 2.1(2019).