Global diffeomorphism of the Lagrangian flow-map defining equatorially trapped water waves

The aim of this paper is to prove that a three dimensional Lagrangian flow which defines equatorially trapped water waves is dynamically possible. This is achieved by applying a mixture of analytical and topological methods to prove that the nonlinear exact solution to the geophysical governing equations, derived by Constantin (2012), is a global diffeomorphism from the Lagrangian labelling variables to the fluid domain beneath the free surface.