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Quantifying error in the radiative forcing of the first aerosol indirect effect
Author(s) -
McComiskey Allison,
Feingold Graham
Publication year - 2008
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2007gl032667
Subject(s) - aerosol , radiative forcing , forcing (mathematics) , radiative transfer , environmental science , atmospheric sciences , climatology , meteorology , physics , geology , optics
Anthropogenic aerosol plays a major role in the Earth's radiation budget, particularly via effects on clouds. The Intergovernmental Panel on Climate Change lists the uncertainty in aerosol modification of cloud albedo as the largest unknown in the radiative forcing of climate change. Common measures of aerosol effects on clouds, Aerosol‐Cloud Interaction (ACI = −∂ln r e /∂ln α , where r e is drop size and α aerosol burden), cover an enormous range and, as these measures are now being used as parameterizations in global‐scale models, this has large implications for radiative forcing. We quantify the relationship between radiative forcing and changes in ACI over the range of values found in the literature. Depending on anthropogenic aerosol perturbation, radiative forcing ranges from −3 to −10 W m −2 for each 0.05 increment in ACI. Narrowing uncertainty in measures of ACI to an accuracy of 0.05 would place estimated cloud radiative forcing on a sounder footing.