Range-dependent matched-field geoacoustic inversion using a tonal source towed on circular tracks

Area of Science:

• Oceanography
• Acoustics
• Geophysics

Background:

• Acoustic properties of marine sediments are crucial for understanding sound propagation.
• Spatial variability in seabed characteristics impacts acoustic models.
• Previous methods lacked the ability to fully capture range-dependent geoacoustic properties.

Purpose of the Study:

• To estimate acoustic properties and their spatial variability on the New England Mud Patch.
• To develop and validate an advanced Bayesian geoacoustic inversion method.
• To assess the range dependence of water depth and sediment thickness.

Main Methods:

• Utilized tonal signals (303-953 Hz) from a towed source and a vertical line array.
• Developed a Metropolis-Hastings (MH) method incorporating adaptation, principal-component updates, and parallel tempering.
• Employed an observation model based on adiabatic normal modes for sound propagation.
• Parametrized geoacoustic models with linear depth-dependent properties, focusing on sound speed.

Main Results:

• Accurately estimated mud-related geoacoustic parameters.
• Successfully determined the range dependence of water depth and upper-sediment mud thickness.
• Demonstrated the effectiveness of the advanced MH method compared to a range-independent reference.

Conclusions:

• The developed MH method provides accurate geoacoustic parameter estimation, including spatial variability.
• The approach effectively models range-dependent acoustic properties in marine environments.
• This study enhances seabed characterization capabilities for acoustic applications.