Underwater-Sound Ray and Refractive-Anomaly Plots Made with an Analog Computer

Abstract

A computer program has been developed that traces sound rays and gives a continuous value for the refractive anomaly. The program uses the second derivative of the sound velocity with respect to depth as a description of the medium, and this quantity is developed by a function generator as a function of depth. Ray and anomaly plots have been made with a simulated projector located at various depths. The depths were chosen so that rays emitted by the projector would pass horizontally through depth layers where the second derivative is large and negative, large and positive, and zero. The plots show that divergence zones arise when rays travel horizontally for long distances in layers where the second derivative of the velocity with respect to depth is large and negative. Convergent effects occur when rays travel horizontally for long distances in layers where the second derivative of the velocity with respect to depth is large and positive. Refractive effects are small only when the rays encounter no regions of extreme values of the second derivative or when the influence of one extreme region is nullified by another.