Analysis of the Improvement in Implied Meridional Ocean Energy Transport as Simulated by the NCAR CCM3

Abstract

The implied meridional ocean energy transport diagnosed from uncoupled integrations of two atmospheric general circulation models?the National Center for Atmospheric Research Community Climate Model versions 2 and 3 (CCM2 and CCM3)?shows radically different transport characteristics throughout much of the Southern Hemisphere. The CCM2 simulation requires an equatorward transport of energy by the oceans, and the CCM3 exhibits a poleward energy transport requirement, very similar to what is derived from observational analyses. Previous studies have suggested that errors in the implied ocean energy transport are largely attributable to errors in the simulated cloud radiative forcing. The results of this analysis show that although the proper simulation of the radiative effects of clouds is likely to be a necessary condition for realistic meridional ocean energy transport, it is not sufficient. Important changes in the CCM3 equatorial surface latent heat fluxes, associated with a deep formulation for parameterized moist convection, are primarily responsible for the improved ocean energy transport, where this change in the surface energy budget is much more weakly reflected in top-of-atmosphere differences in cloud radiative forcing.