Am guessing that the Walker circulation, as a 2-dimensional flow, might over-simplify the actual atmospheric dynamics? Wondering if the Hadley circulation needs to be factored in to the considerations.? If the outflow from the top of the deep convection over the pool(s) of warmest Pacific equatorial waters has a more meridional flow (Hadley cell) than zonal flow (Walker cell) then the resultant return flow (easterly winds) along the equator at the ocean surface might be weaker. And conversely if the mass and heat momentum out of the tops of the towering TRWs is 'jetting' zonally towards the East then the resultant easterly surface winds would be stronger and help initiate the La Nina conditions. How are the Hadley cells factored into the models?