Hui Su, Jonathan H. Jiang, Chengxing Zhai, Tsaepyng J. Shen, J. David Neelin, Graeme L. Stephens and Yuk L. Yung, 2014:
J. Geophys. Res., 119, 5787-5805, doi:10.1002/2014JD021642.
Paper (pdf 6.7 MB)
© Copyright 2014 by the American Geophysical Union.
Abstract. 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 CO2. 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.
Citation. Su, H., J. H. Jiang, C. Zhai, T. J. Shen, J. D. Neelin, G. L. Stephens and Y. L. Yung, 2014: Weakening and Strengthening Structures in the Hadley Circulation Change under Global Warming and Implications for Cloud Response and Climate Sensitivity. J. Geophys. Res., 119, 5787-5805, doi:10.1002/2014JD021642.
Acknowledgments. We are thankful to Jay Mace, Eric J. Fetzer and William G. Read for helpful discussions of data quality. Discussions with Kevin Bowman, Duane Waliser and Michael Gunson are appreciated. The manuscript is greatly improved owing to the detailed comments and constructive suggestions by Mark Zelinka and two other reviewers. We acknowledge the World Climate Research Programme's Working Group on Coupled Modelling, which is responsible for CMIP. We thank the climate modeling groups listed in Table 1 for producing and making available their model output. The US Department of Energy (DOE) Program for Climate Model Diagnosis and Intercomparison provides coordinating support and led development of software infrastructure in partnership with the Global Organization for Earth System Science Portals. The A-Train satellite data are available at NASA Distributed Active Archive Centers (DAAC). HS, JHJ, CZ and JTS acknowledge funding support from NASA NEWS, COUND and AST programs and Aura MLS and CloudSat projects. JDN was supported by NOAA NA11OAR4310099 and NSF AGS-1102838. YLY was supported by UHOUST.130027 subcontract from the University of Houston. This work was performed at Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. An edited version of this paper was published by AGU. Copyright (2014) American Geophysical Union. To view the published open abstract, go to AGU Paper.