Applied Underwater Acoustics

2.8. Three-Dimensional Propagation

In a horizontally stratified ocean the sound field from a point source is azimuthally uniform and hence can be described in terms of just two spatial coordinates, horizontal range and depth. Such a field is said to be two-dimensional, even though it occupies a three-dimensional space. When variable stratification is present, associated with nonuniform bathymetry or a laterally varying sound speed, the acoustic field is three-dimensional in that it depends on three spatial coordinates, usually though not always taken to be horizontal range, depth, and azimuth about the source position.

In shallow water with variable bathymetry, the slope of the bottom is often the main cause of horizontal deflections: acoustic ...