Computational studies of time-varying three-dimensional acoustic propagation in canyon and slope regions

A three-dimensional acoustic propagation code is united with fields from a regional ocean model to study time-varying acoustic propagation behavior in realistic environments. The resultant four-dimensional acoustic fields are examined here. The regional models used to date for this purpose have the limitations of invoking the hydrostatic approximation and having spatial resolution that is of order one-hundred times the acoustic wavelength. Examples chosen for analysis here are from canyon and slope regions near the continental shelf break (shelf edge). In this area, bathymetric effects on flow and highly variable sound interaction with the seafloor work to generate complex acoustic field behavior. Some features of sound fields are governed by the bathymetry and are steady in time. Other features are governed by variations on the water column and fluctuate.