Waveguide invariant analysis for modeling time-frequency striations in a range-dependent environment

Abstract

The waveguide invariant is a useful parameter for understanding the behavior of interference patterns (e.g., striations in time–frequency plots) resulting from broadband acoustic sources in shallow water waveguides. It is possible to model these striations for range-dependent environments using conventional parabolic equation methods; although this approach can be computationally intensive as a full field must be created for each frequency and azimuthally dependent geometry. This letter discusses the formulation and use of a range-dependent waveguide invariant distribution that can be used to describe spectral striation patterns using a fraction of the computing power required by parabolic equation methods.