Inversion of seabed attenuation using time-warping of close range data

Area of Science:

• Acoustic oceanography
• Geophysical inversion
• Seabed characterization

Background:

• Accurate estimation of seabed acoustic properties is crucial for underwater acoustics and geophysical surveys.
• Modal dispersion in acoustic signals contains valuable information about the seabed's physical characteristics.
• Traditional methods for seabed sound attenuation estimation can be complex and require specialized equipment.

Purpose of the Study:

• To develop and validate a novel inversion scheme for estimating seabed sound attenuation.
• To utilize modal dispersion from close-range single-hydrophone data for seabed property inversion.
• To apply the method to experimental data and assess its effectiveness in a real-world scenario.

Main Methods:

• A time-warping based inversion scheme was developed to extract dispersion information from signal spectra.
• Seabed sound speed and density were inverted using modal group velocity curves.
• Seabed sound attenuation was inverted from normalized modal amplitudes.

Main Results:

• The inversion scheme was successfully applied to experimental data collected in the Yellow Sea.
• Inverted sound speed and density values were consistent with local sand-silt-clay sediment composition.
• A nonlinear relationship between seabed sound attenuation and frequency (125-500 Hz) was observed.

Conclusions:

• The time-warping inversion method provides an effective means to estimate seabed sound attenuation and properties.
• The study demonstrates the utility of modal dispersion analysis for characterizing seabed acoustic properties.
• The findings highlight the frequency-dependent, nonlinear nature of sound attenuation in specific marine sediments.