A quasi-biennial oscillation in the equatorial Atlantic Ocean

A quasi-biennial oscillation with features characteristic of equatorial coupled modes is found in the equatorial Atlantic Ocean. The origins of the phenomenon are investigated by using a coupled atmosphere-ocean general circulation model, in which the fully coupled domain is restricted to the Tropical Atlantic (20°S-30°N). The simulations capture a similar oscillation regardless of whether sea surface temperatures prescribed outside the coupled domain correspond to the observed or the climatology (i.e., lack year-to-year variability). It is concluded that the equatorial Atlantic hosts a quasi-biennial oscillation generated by coupled atmosphere-ocean interactions internal to the basin with little influence from remote events, even from El Niño/Southern Oscillation.