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Weakening and strengthening structures in the Hadley Circulation change under global warming and implications for cloud response and climate sensitivity
Author(s) -
Su Hui,
Jiang Jonathan H.,
Zhai Chengxing,
Shen Tsaepyng J.,
Neelin J. David,
Stephens Graeme L.,
Yung Yuk L.
Publication year - 2014
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2014jd021642
Subject(s) - hadley cell , environmental science , climatology , climate sensitivity , atmospheric sciences , cloud fraction , climate model , climate change , cloud cover , general circulation model , circulation (fluid dynamics) , cloud feedback , atmospheric circulation , global warming , cloud computing , geology , physics , computer science , oceanography , thermodynamics , operating system
It has long been recognized that differences in climate model‐simulated cloud feedbacks are a primary source of uncertainties for the model‐predicted surface temperature change induced by increasing greenhouse gases such as CO 2 . Large‐scale circulation broadly determines when and where clouds form and how they evolve. However, the linkage between large‐scale circulation change and cloud radiative effect (CRE) change under global warming has not been thoroughly studied. By analyzing 15 climate models, we show that the change of the Hadley Circulation exhibits meridionally varying weakening and strengthening structures, physically consistent with the cloud changes in distinct cloud regimes. The regions that experience a weakening (strengthening) of the zonal‐mean circulation account for 54% (46%) of the multimodel‐mean top‐of‐atmosphere (TOA) CRE change integrated over 45°S–40°N. The simulated Hadley Circulation structure changes per degree of surface warming differ greatly between the models, and the intermodel spread in the Hadley Circulation change is well correlated with the intermodel spread in the TOA CRE change. This correlation underscores the close interactions between large‐scale circulation and clouds and suggests that the uncertainties of cloud feedbacks and climate sensitivity reside in the intimate coupling between large‐scale circulation and clouds. New model performance metrics proposed in this work, which emphasize how models reproduce satellite‐observed spatial variations of zonal‐mean cloud fraction and relative humidity associated with the Hadley Circulation, indicate that the models closer to the satellite observations tend to have equilibrium climate sensitivity higher than the multimodel mean.