A history of ray‐theory development at Naval Ocean Systems Center

Abstract

This paper presents examples of the evolution of ray theory of underwater acoustics at the Naval Ocean Systems Center and its predecessor laboratories since 1952. The motivations for this evolution were to bring ray‐theory results into better agreement with experiments, to distinguish true acoustic properties of the ocean from artifacts resulting from the sound‐speed model or from shortcomings in ray theory, and to develop simple controls for use in evaluating complicated propagation models. Examples of such controls are the five‐parameter Epstein profile, profiles for which various ray pencils focus at a point, and closed‐form solutions for profiles with range as well as depth dependence. The most significant topics presented are the development of continuous‐gradient sound‐speed profiles, the effect of Earth's curvature and of improvements in experimental sound speeds, the application of uniform asymptotics in the boundary layer about caustics, and the development of a method using complex parameters for the evaluation of shadow‐zone fields. Various examples of ray‐theory propagation losses are compared with experiment or with the results of normal‐mode theory.This paper presents examples of the evolution of ray theory of underwater acoustics at the Naval Ocean Systems Center and its predecessor laboratories since 1952. The motivations for this evolution were to bring ray‐theory results into better agreement with experiments, to distinguish true acoustic properties of the ocean from artifacts resulting from the sound‐speed model or from shortcomings in ray theory, and to develop simple controls for use in evaluating complicated propagation models. Examples of such controls are the five‐parameter Epstein profile, profiles for which various ray pencils focus at a point, and closed‐form solutions for profiles with range as well as depth dependence. The most significant topics presented are the development of continuous‐gradient sound‐speed profiles, the effect of Earth's curvature and of improvements in experimental sound speeds, the application of uniform asymptotics in the boundary layer about caustics, and the development of a method using complex parameters fo...