Jan said:
>  The Pacific is an unusual system: It's the only place (presently) on the planet where you have a big stretch of ocean where the Coriolis force is essentially zero, along the Equator.

Agree. What I want to do next is perturb the equatorial-only analytic solution with the off-latitude Coriolis factors and see if there is an elegant way to capture the TIW vortices. It may not remain analytic but there is still the travelling wave part of the solution I haven't explored.

As with electromagnetic modelling, looking at quasi-static behavior - standing wave vs travelling wave, etc - is always enlightening.