Quantifying the effects of roughness scattering on reflection loss measurements

Area of Science:

• Ocean acoustics
• Geophysics
• Acoustic modeling

Background:

• Seafloor acoustic reflection is crucial for sonar and underwater communication.
• Accurate modeling requires understanding sediment properties and interface roughness.
• Previous models often simplified seafloor complexity.

Purpose of the Study:

• To experimentally validate acoustic modeling techniques for seafloor reflection.
• To compare measured reflection loss with predictions from elastic, poro-elastic, and rough interface models.
• To assess the impact of seafloor roughness and sediment properties on acoustic reflection.

Main Methods:

• Measured seafloor reflection loss (magnitude and phase) from 5-80 kHz at grazing angles 7°-77°.
• Quantified seafloor roughness using a laser profiler.
• Measured concurrent geoacoustic parameters (sound speed, density).
• Compared experimental data against flat interface elastic, Biot/Stoll poro-elastic, and rough interface models.

Main Results:

• Experimental reflection loss data showed highest consistency with the poro-elastic model including scattering.
• A flat interface elastic model consistently overpredicted reflection loss.
• Measured data exhibited greater variability than predicted, attributed to layering and medium fluctuations.

Conclusions:

• Poro-elastic models incorporating scattering provide a more accurate representation of seafloor acoustic reflection.
• Seafloor roughness and subsurface layering significantly influence acoustic reflection patterns.
• Experimental validation is key to refining underwater acoustic propagation models.