Intraseasonal and Interannual Oscillations in Coupled Ocean-Atmosphere Models

Abstract

Abstract This study investigates the behavior of coupled ocean-atmosphere models in an environment where atmospheric wave speeds are considerably reduced from their dry atmospheric values, by, for example, condensation-moisture convergence. Preliminary coupled-model results presented earlier are verified and extended using more complete models and for a range of ocean thermodynamics. The models consist of linear coupled shallow-water equations for the equatorial β-plane and are distinguished by the form of the equation for sea-surface temperature. The ocean is forced by wind stress, and the atmosphere by latent heating resulting from (i) moisture convergence and (ii) evaporation. Modes are calculated for zonally periodic, unbounded, ocean-atmosphere systems. The results in this paper emphasize the importance of including prognostic atmospheric equations in simple, coupled ocean-atmosphere models, especially for the simulation of intraseasonal variability and its possible interaction with interannual varia...