Eigenray tracing in an ocean using Fermat's principle

Abstract

A novel numerical approach is presented for solving the problem of three-dimensional eigenray tracing in an ocean channel. A variational method is developed based on Fermat's principle which yields eigenrays directly without having to search for a ray which reaches the receiver. The algorithm yields "true" Fermat rays: i.e., eigenrays for which the travel-time is stationary rather than minimal. The numerical results included in this paper show the algorithm to be more accurate and faster than a method based on Snell's law.