Assessment of Cloud-Climate Feedback Simulation Bias of Coupled Ocean-Atmosphere Model in the Tropical Pacific
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Abstract
Cloud-climate feedback is an important process of air-sea interaction and it is a primary difficulty of climate simulation. By using results of the 20C3M coupled ocean-atmosphere models from the IPCC AR4 (Fourth Assessment Report of the Intergovernmental Panel on Climate Change) and observed data, interannual and interdecadal signals of the tropical Pacific sea surface temperature (SST) were extracted with the methods of filtering and Empirical Orthogonal Function (EOF). Then the authors calculated interannual and interdecadal cloud and heat flux feedback. Both interannual and interdecadal cloud and heat flux feedback of coupled ocean-atmosphere models are weaker than that from the reanalysis and observed data. The weakness may be caused by weaker sensitivity of tropical convection and cloud-to-SST change of coupled ocean-atmosphere models than real ocean-atmosphere. Though interdecadal thermodynamical feedback of coupled ocean-atmosphere models is weaker, SST interdecadal warming trend of coupled ocean-atmosphere models in the tropical Pacific between 10°S and 10°N is equivalent to the observed data. Only interdecadal thermodynamical feedback is not enough to explain the climate change of the tropical Pacific, the interdecadal dynamical feedback effect also must be considered.
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