Roughness influence on multibeam-subbottom-profiler specular echoes and roughness parameter inversion.

Area of Science:

• Oceanography
• Acoustics
• Wave Scattering

Background:

• Wave scattering models often omit source and receiver directivity.
• Integrating directivity provides clearer physical interpretations of scattering phenomena.

Purpose of the Study:

• To develop integral solutions for wave scattering over slightly rough surfaces that incorporate source and receiver directivity.
• To derive spatial covariances and variances for specular echoes in a multibeam-subbottom-profiler configuration.
• To establish a method for extracting surface roughness parameters.

Main Methods:

• Integrating point source and point receiver solutions over source and receiver apertures.
• Deriving scintillation, time-of-arrival, and direction-of-arrival spatial covariances.
• Obtaining algebraic expressions for variances with Gaussian autocorrelation and apodization functions.
• Numerical evaluation of surface integrals and comparison with 3D numerical experiments.

Main Results:

• Integral solutions with clear physical interpretations were achieved by incorporating directivity.
• Surface integrals for covariances were derived and numerically evaluated.
• Algebraic expressions for variances were obtained for specific roughness and array functions.
• Numerical results closely matched estimates from a realistic 3D numerical experiment.

Conclusions:

• The integration of source and receiver directivity offers a physically interpretable approach to wave scattering.
• The derived covariances and variances are applicable to multibeam-subbottom-profiler systems.
• A simple inversion scheme effectively extracts roughness parameters from experimental signals.