Modes of Interannual Tropical Ocean–Atmosphere Interaction—a Unified View. Part III: Analytical Results in Fully Coupled Cases

Abstract The parameter-space dependence of the eigenmodes of the coupled tropical ocean-atmosphere system, linearized about a climatological basic state, is further examined in a stripped-down intermediate coupled model using the formulation derived in Part II of this study to permit analytical treatment for a finite ocean basin. Part II examined the limit of weak coupling and showed the rapid transition to the mixed SST/ocean dynamics modes of Part I, where it was argued that realistically coupled modes are best understood from strong coupling. Here cases with order unity and larger coupling are explored to provide analytical prototypes for the fully coupled case from a system that explicitly treats spatial structure in a finite basin. The coupled dynamics is explored for several regions of parameter space where simplifications are possible, as well as for the transition from the well-separated case to mixed modes. The case of surface-layer processes only provides a simple example of westward-propagating...