Depth-Dependent Geoacoustic Inferences With Dispersion at the New England Mud Patch via Reflection Coefficient Inversion

Depth-dependent geoacoustic properties are inferred from wide-angle frequency-domain reflection-coefficient data at two sites with different mud-layer thicknesses on the New England Mud Patch. A trans-dimensional Bayesian inversion is employed to estimate geoacoustic properties and uncertainties fro...

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Bibliographic Details
Published in:IEEE journal of oceanic engineering 2020-01, Vol.45 (1), p.69-91
Main Authors: Belcourt, Josee, Holland, Charles W., Dosso, Stan E., Dettmer, Jan, Goff, John A.
Format: Article
Language:English
Subjects:
Acoustic measurements
Acoustic velocity
Acoustics
Angle of reflection
Attenuation
Bayesian geoacoustic inversion
Data
Dispersion
Frequency dependence
Inversion
Measuring instruments
Mud
New England Mud Patch
Probability theory
Properties
Reflectance
Reflection
Sea measurements
Seabed Characterization Experiment (SBCEX)
Sediment
sediment acoustics
Sediments
Shearing
Sound velocity
Spherical waves
Thickness
Transition layers
Velocity
Velocity distribution
Velocity profiles
viscous grain shearing (VGS)
Wave reflection
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Summary:Depth-dependent geoacoustic properties are inferred from wide-angle frequency-domain reflection-coefficient data at two sites with different mud-layer thicknesses on the New England Mud Patch. A trans-dimensional Bayesian inversion is employed to estimate geoacoustic properties and uncertainties from these data using the viscous grain shearing sediment model and spherical wave reflection-coefficient predictions. Results near the thick-mud (SWAMI) site show a nearly uniform sound velocity over the upper approximately 9.2m, followed by a transition layer with velocity increasing nonlinearly by ~280 m/s over 1.8 m. At the thin-sediment (VC31-2) site, the velocity profile exhibits a similar transition layer. Estimates of intrinsic velocity and attenuation dispersion are also obtained. Over the measurement band of about 400-1300 Hz, the velocity in the fine-grained sediments (mud) at both sites varies by only a few meters per second, i.e., velocity is nearly independent of frequency. The attenuation of the fine-grained sediments at both sites follows a nearly linear frequency dependence. The geoacoustic inferences compare reasonably closely with independent measurements including core measurements, chirp-reflection data, and angle of intromission data.
ISSN:0364-9059
1558-1691
DOI:10.1109/JOE.2019.2900115