Simulation of the tropical Pacific climate with a coupled ocean- atmosphere general circulation model. Part II: interannual variabilty

Abstract

Two multiyear simulations with a coupled ocean-atmosphere general circulation model (GCM) - totalling 45 years - are used to investigate interannual variability at the equator. The model consists of the UCLA global atmospheric GCM coupled to the GFDL oceanic GCM, dynamically active over the tropical Pacific. Multichannel singular spectrum analysis along the equator identifies ENSO-like quasi-biennial (QB) and quasi-quadrennial (QQ) modes. Both consist of predominantly standing oscillations in sea surface temperature and zonal wind stress that peak in the central or east Pacific, accompanied by an oscillation in equatorial thermocline depth that is characterized by phase shift of about 90° across the basin, with west leading east. -from Authors