Buoyancy-driven interannual sea level changes in the southeast tropical Pacific

It is commonly held that interannual-to-decadal sea level variability patterns mainly represent the ocean\textquoterights response to wind forcing. This view is based in part on modeling studies of wind-driven sea level changes along the tropical Pacific. However, because buoyancy forcing (and other generating mechanisms) are usually ignored, this paradigm may overemphasize the role of winds. Focusing on the southeast tropical Pacific, we use a data-constrained ocean state estimate to demonstrate that distinct mechanisms\textemdashincluding the ocean\textquoterights response to buoyancy forcing as well as nonlinear processes\textemdashcan also contribute to interannual sea level variability. Contrary to the notion that buoyancy-driven sea level changes are dynamically passive, such changes exhibit a strongly nonlocal, dynamically active character, made manifest in westward propagating waves. As similar findings apply elsewhere, accurate modeling of interannual-to-decadal regional sea level changes requires consideration of a variety of forcing mechanisms, including, but not limited to, the winds.