Influence of ocean-atmosphere coupling on the properties of tropical instability waves

Abstract

In this study we investigate how the modulation of surface wind-stress by tropical instability waves (TIWs) feeds back onto TIWs and plays a role in their fundamental properties. An ocean general circulation model is used, that reproduces qualitatively well the properties of TIWs when forced by climatological winds, although with a 30% underestimated amplitude. The ocean model is coupled to the atmosphere through a simple parameterization of the wind stress response to SST. The properties of the TIWs in the coupled simulations are compared with those without active coupling. Active coupling results in a negative feedback on TIWs, slightly reducing their temperature and meridional current variability, both at the surface and sub-surface. This reduced activity modulates the meridional heat and momentum transport, resulting in modest changes to the mean state, with a cooler cold tongue and stronger equatorial currents. Copyright 2004 by the American Geophysical Union.