Tropical pacific sea surface temperature variations in a coupled atmosphere-ocean general circulation model

Abstract

A Pacific Ocean general circulation model (horizontal resolution of 5° in longitude and 4° in latitude) is coupled with a global atmospheric general circulation model, both developed at the Meteorological Research Institute/Japan Meteorological Agency, to study the coupled atmosphere-ocean system in the tropical Pacific Ocean. Without any flux correction in the atmosphere-ocean interaction, seasonal variation of equatorial sea surface temperature ( SST) is reasonably simulated, though interannual and intraseasonal variations in the model are smaller than the observed variations. Although cooling trend of the equatorial SST is apparent in the initial 1–2 years, SST attains to a stable state with 1–2°C cooler than the observed SST in the western equatorial Pacific. The east-west difference of the model equatorial SST is smaller than the observed one mainly because the easterly wind in the eastern equatorial Pacific is not strong enough to upwell cold water there.