Theoretical and Applied Climatology

, Volume 110, Issue 1–2, pp 1–10 | Cite as

Climate sensitivity and cloud feedback processes imposed by two different external forcings in an aquaplanet GCM

Original Paper

Abstract

The sensitivity of climate to an increase in sea surface temperature (SST) and CO2, as well as cloud feedback processes, is analyzed through a series of aquaplanet experiments listed in the Coupled Model Intercomparison Project. Rainfall is strengthened in a +4K anomaly SST experiment due to the enhanced surface evaporation; while in a quadruple CO2 experiment, precipitation and total cloud cover are appreciably weakened. In both the +4K and quadruple CO2 (4xCO2) experiments, the Hadley cell is impaired, with an increase in moderate subsidence and a decrease in the frequency of strong convective activity. Regarding cloud radiation forcing (CRF), the analysis technique of Bony et al. (Climate Dynamics, 22:71–86, 2004) is used to sort cloud variables by dynamic regimes using the 500-hPa vertical velocity in tropical areas (30°S–30°N). Results show that the tropically averaged CRF change is negative and is dominated mainly by the thermodynamic component. Within convective regimes, the behavior of longwave CRF is different in the +4K and 4xCO2 experiments, with positive and negative changes, respectively. The globally averaged CRF also reveals a negative change in both aquaplanet and Earthlike experiments, implying that clouds may play a role in decelerating global warming. The calculated climate sensitivity demonstrates that our results are close to those obtained from other models, with 0.384 and 0.584 Km2 W−1 for aquaplanet and Earthlike experiments, respectively.

Notes

Acknowledgments

This research was supported by the “Strategic Priority Research Program—Climate Change: Carbon Budget and Relevant Issues” of the Chinese Academy of Sciences (XDA05110303), the National Key Basic Research Program (2012CB417203), and National Science Foundation of China (40805038 and 41023002).

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Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  • Xiaocong Wang
    • 1
    • 2
  • Yimin Liu
    • 1
  • Qing Bao
    • 1
  • Zaizhi Wang
    • 3
  1. 1.State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric PhysicsChinese Academy of SciencesBeijingChina
  2. 2.Graduate University of Chinese Academy of SciencesBeijingChina
  3. 3.National Climate CenterChina Meteorological AdministrationBeijingChina

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