Sensitivity of a Coupled Ocean–Atmosphere Model to Physical Parameterizations

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  • 1 Department of Atmospheric Sciences, University of California, Los Angeles, Los Angeles, California
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Abstract

The sensitivity of a coupled ocean–atmosphere general circulation model to parameterizations of selected physical processes is studied. The parameterizations include those of longwave radiation and surface turbulent fluxes in the atmospheric model, and those of vertical turbulent mixing and penetration of solar radiation in the ocean model. It is shown that the performance of the coupled model is highly sensitive to the parameterization of longwave radiation. This sensitivity is not solely due to the difference in surface radiative flux but involves interactions among radiation, convection, and large-scale dynamics of the atmosphere and ocean. It is concluded that differences in parameterizations can have large impacts on the performance of the coupled model, and these impacts can be very different from what may be expected from uncoupled model simulations.

Abstract

The sensitivity of a coupled ocean–atmosphere general circulation model to parameterizations of selected physical processes is studied. The parameterizations include those of longwave radiation and surface turbulent fluxes in the atmospheric model, and those of vertical turbulent mixing and penetration of solar radiation in the ocean model. It is shown that the performance of the coupled model is highly sensitive to the parameterization of longwave radiation. This sensitivity is not solely due to the difference in surface radiative flux but involves interactions among radiation, convection, and large-scale dynamics of the atmosphere and ocean. It is concluded that differences in parameterizations can have large impacts on the performance of the coupled model, and these impacts can be very different from what may be expected from uncoupled model simulations.

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