Constraining the instantaneous aerosol influence on cloud albedo

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Title: Constraining the instantaneous aerosol influence on cloud albedo
Authors: Gryspeerdt, E
Quaas, J
Ferrachat, S
Gettelman, A
Ghan, S
Lohmann, U
Morrison, H
Neubauer, D
Partridge, DG
Stier, P
Takemura, T
Wang, H
Wang, M
Zhang, K
Item Type: Journal Article
Abstract: Much of the uncertainty in estimates of the anthropogenic forcing of climate change comes from uncertainties in the instantaneous effect of aerosols on cloud albedo, known as the Twomey effect or the radiative forcing from aerosol–cloud interactions (RFaci), a component of the total or effective radiative forcing. Because aerosols serving as cloud condensation nuclei can have a strong influence on the cloud droplet number concentration (Nd), previous studies have used the sensitivity of the Nd to aerosol properties as a constraint on the strength of the RFaci. However, recent studies have suggested that relationships between aerosol and cloud properties in the present-day climate may not be suitable for determining the sensitivity of the Nd to anthropogenic aerosol perturbations. Using an ensemble of global aerosol–climate models, this study demonstrates how joint histograms between Nd and aerosol properties can account for many of the issues raised by previous studies. It shows that if the anthropogenic contribution to the aerosol is known, the RFaci can be diagnosed to within 20% of its actual value. The accuracy of different aerosol proxies for diagnosing the RFaci is investigated, confirming that using the aerosol optical depth significantly underestimates the strength of the aerosol–cloud interactions in satellite data.
Issue Date: 26-Apr-2017
Date of Acceptance: 17-Mar-2017
ISSN: 1091-6490
Publisher: National Academy of Sciences
Start Page: 4899
End Page: 4904
Journal / Book Title: Proceedings of the National Academy of Sciences of the United States of America
Volume: 114
Issue: 19
Copyright Statement: © 2017 National Academy of Sciences
Keywords: Science & Technology
Multidisciplinary Sciences
Science & Technology - Other Topics
radiative forcing
MD Multidisciplinary
Publication Status: Published
Appears in Collections:Space and Atmospheric Physics
Faculty of Natural Sciences

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