Range-Dependent Waveguide

Abstract

In the previous chapters we have considered the propagation of sound in the ocean where the depth, the acoustical characteristics of the sea bottom, and the sound velocity profile c(z) in water do not vary along the propagation path. Very often this is a rather good approximation to a real situation and, therefore, the theory developed above has a wide variety of practical applications. Sometimes, however, we need the generalization of this theory to the case when the characteristics of the ocean acoustic waveguide vary with a horizontal range. It is necessary, in particular, a) when sound propagates in the coastal wedge, where variation of sea depth is significant; b) when sound waves cross frontal zones in the ocean, for example, such currents as the Gulf Stream, Kuroshio, etc.; and c) when sound propagates over large ranges of the order of thousands of kilometres. Variation of the c(z) profile is essential in this case, especially when the propagation path lies in the meridional direction.