Effective range derivative for acoustic propagation loss in a horizontally stratified ocean

Abstract

A method for predicting acoustic propagation loss in a horizontally stratified ocean had been developed. We begin by comparing two widely used models, and demonstrate that unresolved discrepancies exist. Then classical ray tracing equations are developed by evaluating a multipath integral by stationary phase. The inaccuracy of ray theory is attributed to deficiencies in the stationary phase approach. In order to correct these shortcomings, we express multipaths in terms of Fresnel integrals and effective range derivatives. The approach is generalized to shadow zone propagation. Finally, we introduce a computer model that is based on the effective range derivative evaluation of the multipath expansion. The main emphasis of this paper, however, is not model comparison, but the effective range derivative technique, itself.