Applications of Waveguide Invariant Theory to the Analysis of Interference Phenomena in Deep Water

The waveguide invariant, denoted as β, can be used to describe the slope of the intensity of a broadband acoustic signal. In deep water, the interference patterns of the areas with dominant waterborne modes and only with bottom bounce modes are greatly different. This phenomenon is illustrated by simulation and explained by the distribution of β. The theory shows that in the convergence zone, β approaches infinity, which leads to the larger slope of sound intensity; on the contrary, in the shadow zone, β is close to 1, leading to smaller slopes.