Constraining the instantaneous aerosol influence on cloud albedo.
Edward Gryspeerdt, Johannes Quaas, Sylvaine Ferrachat, Andrew Gettelman, Steven Ghan, Ulrike Lohmann, Hugh Morrison, David Neubauer, Daniel G Partridge, Philip Stier, Toshihiko Takemura, Hailong Wang, Minghuai Wang, Kai Zhang
Author Information
Edward Gryspeerdt: Institute for Meteorology, Universität Leipzig, 04109 Leipzig, Germany; e.gryspeerdt@imperial.ac.uk. ORCID
Johannes Quaas: Institute for Meteorology, Universität Leipzig, 04109 Leipzig, Germany.
Sylvaine Ferrachat: Institute for Atmospheric and Climate Science, ETH Zurich, 8092 Zurich, Switzerland.
Andrew Gettelman: National Center for Atmospheric Research, Boulder, CO 80305.
Steven Ghan: Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, WA 99352.
Ulrike Lohmann: Institute for Atmospheric and Climate Science, ETH Zurich, 8092 Zurich, Switzerland.
Hugh Morrison: National Center for Atmospheric Research, Boulder, CO 80305.
David Neubauer: Institute for Atmospheric and Climate Science, ETH Zurich, 8092 Zurich, Switzerland.
Daniel G Partridge: Department of Environmental Science and Analytical Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden.
Philip Stier: Atmospheric, Oceanic, and Planetary Physics, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom. ORCID
Toshihiko Takemura: Research Institute for Applied Mathematics, Kyushu University, Fukuoka 816-8580, Japan.
Hailong Wang: Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, WA 99352.
Minghuai Wang: Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, WA 99352.
Kai Zhang: Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, WA 99352.
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 ( ), previous studies have used the sensitivity of the 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 to anthropogenic aerosol perturbations. Using an ensemble of global aerosol-climate models, this study demonstrates how joint histograms between 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.
