The influence of thermocline topography on the oceanic response to fluctuating winds: a case study in the tropical north pacific

摘要

We have examined the effect of spatial variations of mean thermocline depth on the oceanic response to fluctuating winds. We have focused our analysis on a relatively narrow latitude band in the tropical North Pacific (～10°-15°N), where enhanced variability is found in the thermocline. The variability is associated with baroclinic Rossby waves forced by anomalous Ekman pumping in the eastern half of the basin. The 10°-15°N band coincides with an area of large meridional gradients in mean thermocline depth. We have shown that anomalous meridional advection of those gradients is primarily responsible for the enhanced variability in that region. Thus, the vertical velocities directly induced by the Ekman pumping are not necessarily the dominant factor in determining the amplitude of the wave field, but the meridional advection of mean thermocline gradients by the anomalous velocities associated with the Rossby waves may play a fundamental role.