Role of non-linear oceanic processes in the response to westerly wind events: new implications for the 1997 El Nino onset

In March 1997, a strong westerly wind event (WWE) occurred in the western e quatorial Pacific prior to the 1997-1998 El Nino event. It produced downwel ling Kelvin waves that interacted non linearly with the surface temperature , salinity and zonal current fronts located at the eastern edge of the warm -fresh pool (EEWP). This non-linear interaction locally increased zonal cur rents by a factor of three compared to a theoretical linear response, and a dvected the EEWP at an unexpected rate (similar to 1m/s) to which the ocean -atmosphere coupled system may have been responding rapidly to trigger El N ino conditions.