The Effects of Surface Gravity Waves on High-Frequency Acoustic Propagation in Shallow Water

A realistic 2-D time-evolving ocean surface model has been combined with an existing acoustic ray-based model to simulate the effects of sea surface roughness on acoustic wave propagation in coastal regions. Rough sea surface realizations are generated and used as sea surface boundaries in the acoustic model. An approach to achieve high resolution and accurate results while maintaining computational efficiency of a ray-based model is applied. The results are then compared against a unique set of experimental data collected in 15-m water depth in Delaware Bay. These data include simultaneous environment and acoustic propagation (1-18 kHz) measurements. Modeled arrival time-angle fluctuations compare well with data and suggest that there are physical processes which need to be included to improve the model, such as bubbles and turbulence as well as 3-D scattering effects.