Acoustic normal modes propagation through ocean eddies

Abstract

Uniformly valid asymptotic solutions are derived for normal mode propagation in a slowly varying ocean waveguide. The limits of validity of various approximations as a function of mode number, acoustic frequency, and range are discussed for realistic ocean environments. In particular, the first correction to the adiabatic equations is calculated, which provides an approximate solution to the coupled mode equations. The implications for numerical calculation of normal modes are discussed.