Kelvin wave and Rossby wave interaction in the extratropical-tropical Pacific

The adjustment of the equatorial Pacific thermocline to an initial extratro pical thermocline anomaly is studied using analytical and high-resolution(1 /16 degrees) primitive equation numerical models. It is found that the fast adjustment due to the coastal Kelvin wave and equatorial Kelvin and Rossby waves, and the slow adjustment due to the eastern boundary planetary wave play important roles in the redistribution of the initial anomalous mass, t hereby determining the phase and magnitude of the equatorial thermocline tr ansition induced by the initial extratropical thermocline transition. For a given extratropical anomaly, both analytical and numerical models show tha t the equatorial thermocline transition occurs about 2-5 years later, and t he magnitude is about 5 - 10% of the initial anomaly. The mean circulation in the North Pacific intensifies the transition of the equatorial thermocli ne and reduces the phase-lag of extratropical-tropical thermocline transiti on.