Seabed characterization using ambient sound for a range-dependent track in the New England Mud Patcha)

Wind-generated, ocean ambient sound data were used to characterize seabed properties along a track in the New England Mud Patch. A 15-m vertical array, consisting of 16 hydrophones, collected ambient sound data across the 50-5000 Hz frequency band. The array drifted for 1 h, covering a 1.7 km track. Seabed characterization was performed using beamforming techniques, which limited the analysis to the 400-700 Hz band. Passive fathometer processing was applied to estimate the water-seabed interface and sub-bottom layering. Additionally, the data were used to estimate the power reflection coefficient, which was then used as input for a trans-dimensional geoacoustic inversion. The results showed the track had slight range dependence, which was evident in the layering structure. The estimated seabed properties-sound speed, density, and attenuation-were consistent along the track but also showed slight range-dependent variability.