Shallow water sound propagation with surface waves.

Area of Science:

• Underwater acoustics
• Wave propagation modeling
• Oceanography

Background:

• Traditional acoustic models struggle with rapidly changing underwater environments.
• Surface waves introduce complex reflections, focusing, and defocusing effects.
• Shallow water acoustics present unique challenges for wave propagation.

Purpose of the Study:

• To extend wavefront modeling theory for range-dependent underwater environments.
• To incorporate effects of surface waves on acoustic propagation.
• To accurately model pulse propagation in shallow water with dynamic boundaries.

Main Methods:

• Developed an extended wavefront modeling theory.
• Incorporated multiple reflections from surface and bottom.
• Accounted for focusing/defocusing from surface wave interactions.
• Calculated phase and amplitude directly for time-domain pulse modeling.

Main Results:

• Successfully modeled pulse waveforms for all arrivals, including caustics.
• Demonstrated accurate prediction of insonified and shadow regions.
• Achieved good agreement between calculated waveforms and experimental data.

Conclusions:

• The extended wavefront theory effectively models acoustic pulse propagation in shallow, dynamic waters.
• The model accurately captures complex phenomena like surface wave reflections and caustics.
• Validated by comparison with experimental data from a near-shore environment.