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The nonlinear relationship between albedo and cloud fraction on near‐global, monthly mean scale in observations and in the CMIP5 model ensemble
Author(s) -
Engström A.,
Bender F. A.M.,
Charlson R. J.,
Wood R.
Publication year - 2015
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 - 10.1002/2015gl066275
Subject(s) - cloud albedo , cloud fraction , albedo (alchemy) , environmental science , cloud computing , atmospheric sciences , climate model , cloud forcing , climatology , cloud height , population , cloud top , meteorology , climate change , cloud cover , geology , geography , computer science , art , oceanography , demography , sociology , performance art , art history , operating system
We study the relation between monthly mean albedo and cloud fraction over ocean, 60°S–60°N. Satellite observations indicate that these clouds all fall on the same near‐exponential curve, with a monotonic distribution over the ranges of cloud fractions and albedo. Using these observational data as a reference, we examine the degree to which 26 climate models capture this feature of the near‐global marine cloud population. Models show a general increase in albedo with increasing cloud fraction, but none of them display a relation that is as well defined as that characterizing the observations. Models typically display larger albedo variability at a given cloud fraction, larger sensitivity in albedo to changes in cloud fraction, and lower cloud fractions. Several models also show branched distributions, contrasting with the smooth observational relation. In the models the present‐day cloud scenes are more reflective than the preindustrial, demonstrating the simulated impact of anthropogenic aerosols on planetary albedo.