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

Josee Belcourt, Charles Holland, Stan E. Dosso, Jan Dettmer, John A. Goff

Research output: Contribution to journalArticle

Abstract

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 9.2 m, followed by a transition layer with velocity increasing nonlinearly by <formula><tex>$\sim$</tex></formula>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&#x2013;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.

Original languageEnglish (US)
JournalIEEE Journal of Oceanic Engineering
DOIs
StateAccepted/In press - Jan 1 2019

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Sediments
Acoustic wave velocity
Shearing

All Science Journal Classification (ASJC) codes

  • Ocean Engineering
  • Mechanical Engineering
  • Electrical and Electronic Engineering

Cite this

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title = "Depth-Dependent Geoacoustic Inferences With Dispersion at the New England Mud Patch via Reflection Coefficient Inversion",
abstract = "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 9.2 m, followed by a transition layer with velocity increasing nonlinearly by $\sim$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.",
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Depth-Dependent Geoacoustic Inferences With Dispersion at the New England Mud Patch via Reflection Coefficient Inversion. / Belcourt, Josee; Holland, Charles; Dosso, Stan E.; Dettmer, Jan; Goff, John A.

In: IEEE Journal of Oceanic Engineering, 01.01.2019.

Research output: Contribution to journalArticle

TY - JOUR

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AU - Holland, Charles

AU - Dosso, Stan E.

AU - Dettmer, Jan

AU - Goff, John A.

PY - 2019/1/1

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N2 - 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 9.2 m, followed by a transition layer with velocity increasing nonlinearly by $\sim$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.

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