Ocean Wave Dynamics and the Time Scale of ENSO

Abstract

Abstract A reexamination of the coupled delayed-action oscillator model of Suarez and Schopf for the El Nino/Southern Oscillation (ENSO) phenomenon is made, by deriving it using a parameterized atmosphere and explicit linear ocean wave dynamics. The derivation attempts to clarify the role of boundary reflections, damping, and scale sensitivity in determining the characteristic timescale of the model. Making the assumption that SST anomalies are related to thermocline perturbations in the central to eastern part of the basin, and that wind anomalies are related to SST anomalies, ocean wave dynamics are invoked to solve for the relationship between wind anomalies and the relevant thermocline displacement. A perturbation to SST causes wind anomalies which drive Kelvin waves eastward, thereby increasing the SST perturbation. The wind perturbations also generate Rossby waves in the ocean, which propagate westward, eventually reflecting from the western boundary as Kelvin waves. The thermocline displacements of...