Broadband acoustic characterization of backscattering from a rough stratification interface.

Area of Science:

• Oceanography
• Acoustics
• Fluid Dynamics

Background:

• Acoustic scattering models typically assume smooth interfaces, neglecting real-world roughness.
• Interface roughness in the water column is caused by external forcing and convection.
• Existing models do not fully account for the impact of interface roughness on acoustic backscatter.

Purpose of the Study:

• To extend broadband acoustic backscatter analysis to incorporate interface roughness.
• To develop a method for remotely measuring stratification gradients and sound speed perturbations.
• To analyze how interface roughness affects frequency-dependent acoustic backscattering.

Main Methods:

• Expanded a 1D acoustic model (Weidner and Weber, 2021) to include surface roughness effects.
• Analyzed scattered pressure fields across various interface roughness magnitudes.
• Developed and tested a broadband acoustic inversion procedure using Baltic Sea data.

Main Results:

• Interface roughness significantly modifies frequency-dependent backscattering predictions.
• Root-mean-squared interface slope and height are key quantifiers of roughness impact.
• The broadband inversion method successfully estimated stratification and sound speed perturbations.

Conclusions:

• Interface roughness is a critical factor in acoustic scattering from water column density gradients.
• The developed broadband inversion technique offers a novel approach for remote sensing of underwater stratification.
• Accurate characterization of interface roughness improves acoustic models for oceanographic applications.