Scattering from layered seafloors: Comparisons between theory and integral equations

Area of Science:

• Ocean acoustics
• Geophysics
• Wave scattering

Background:

• Acoustic scattering from layered seafloors depends on geoacoustic properties and interface roughness.
• Existing theoretical models (e.g., small roughness perturbation, Kirchhoff, small slope approximations) yield differing results for scattering and reflection coefficients.
• There is a need to validate these models against a more comprehensive theoretical framework.

Purpose of the Study:

• To present and validate an integral equation for acoustic scattering from a layered seafloor with rough interfaces.
• To compare the accuracy of this integral equation with the small roughness perturbation method and two versions of the small slope approximation.
• To determine the most accurate model for different levels of seafloor roughness.

Main Methods:

• Development of an integral equation model for acoustic scattering from rough, layered seafloor interfaces.
• Comparison of model predictions with established methods: small roughness perturbation and small slope approximations.
• Analysis of scattering cross section and coherent reflection coefficient under varying root-mean-square (rms) roughness conditions.

Main Results:

• The integral equation model provides a benchmark for evaluating other scattering theories.
• The most recent small slope approximation (Jackson and Olson, 2020) demonstrates superior accuracy for large root-mean-square (rms) roughness.
• Agreement between different models increases as the rms roughness decreases.

Conclusions:

• The Jackson and Olson small slope approximation is recommended for modeling acoustic scattering from rough layered seafloors.
• Model selection for seafloor acoustic scattering should consider the degree of interface roughness.
• Further validation of scattering models is crucial for accurate geophysical and ocean acoustic applications.