SURFACE-ENERGY FLUXES AND COUPLED VARIABILITY IN THE TROPICS OF A COUPLED GENERAL-CIRCULATION MODEL

The effect of wind-evaporative feedbacks upon ENSO, and the coupling o f Pacific and Indian Ocean variability, is considered based upon a 110 -yr simulation from a coupled ocean and atmosphere general circulation model. ENSO-like modes, which propagate westward, are found in the mo del Pacific Ocean. Examination of the SST budget shows that the modes amplify and propagate as a result of changes in the surface energy Aux and upwelling rates. Surface flux variability is dominated by the sol ar and evaporative components, and wind-evaporative feedbacks are show n to lead to growth and westward propagation of coupled anomalies in t he model Pacific, a region of mean easterly winds. Eastward propagatin g coupled modes in the model Indian Ocean, a region of mean equatorial westerlies, are also found and are attributed to the same feedback. I nteraction of the Pacific and Indian Ocean modes through the evaporati on field is demonstrated, and their relevance to observed coupled ocea n-atmosphere variability is considered.