Preliminary characterization of surficial sediment acoustic properties and infauna in the New England Mud Patch

Lee, Kevin M.; Ballard, Megan S.; Venegas, Gabriel R.; Wilson, Preston S.; Dorgan, Kelly M.; Reed, Allen H.; Roosen, Ellen

doi:10.1121/2.0000486

Cited by 3 publications

(4 citation statements)

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“…In contrast, mud properties, including subbottom layering, soundspeed gradients due to compaction, and gas content, are of great interest and importance to sound propagation and reverberation and as yet not well understood. Historical in situ data and investigations on mud or fine-grained sediment properties include work from [1]- [8], [31], and [32]. Sediment sound-speed ratio in mud was often found to be less than unity [1]- [4], [31], [32], and sound-speed gradients were often observed [5]- [8], [31].…”

Section: Introductionmentioning

confidence: 99%

“…Historical in situ data and investigations on mud or fine-grained sediment properties include work from [1]- [8], [31], and [32]. Sediment sound-speed ratio in mud was often found to be less than unity [1]- [4], [31], [32], and sound-speed gradients were often observed [5]- [8], [31]. Attenuation measurements were reported in [1], [3], [4], and [31].…”

Section: Introductionmentioning

confidence: 99%

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Measurement of Sound Speed in Fine-Grained Sediments During the Seabed Characterization Experiment

Yang

Jackson

2020

IEEE J. Oceanic Eng.

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The Seabed Characterization Experiment was carried out from March 5 to April 10, 2017 (SBCEX17) on the New England Mud Patch, approximately 90 km south of Martha's Vineyard. The SBCEX17 experimental site covers an area of 11 km × 30 km with water depth in the range of 75-80 m. The Sediment Acoustic-speed Measurement System (SAMS) is designed to measure sediment sound speed and attenuation simultaneously over the surficial 3 m of sediments. During SBCEX17, SAMS was successfully deployed at 18 sites, which were chosen to coincide with coring locations, with the goal of developing a geoacoustic model for the study area. In this article, a summary of SAMS operation during SBCEX17 is presented, as well as preliminary results for sediment sound speed and its spatial variation in the frequency band of 2-10 kHz. It is found that in mud, the sound-speed ratio is in the range of 0.98-1. Little dispersion was observed in this frequency band. Using the preliminary SAMS sound-speed results measured at different depths, the sound-speed gradient in mud within the surficial 3 m favors an exponential rather than a linear dependence at SBCEX17 site. Large gradients are observed for depth shallower than 1.5 m. For the sandy basement beneath the mud layer, the sound-speed ratio is as high as 1.105.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Measurement of Sound Speed in Fine-Grained Sediments During the Seabed Characterization Experiment

Yang

Jackson

2020

IEEE J. Oceanic Eng.

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“…The New England Mud Patch is a ∼13,000 km 2 area roughly 100 km south of Cape Cod, MA, characterized by fine-grained sediments, including clay-and slitsized particles, over a strong reflecting layer composed of coarse-grained (sandy) sediments [18][19][20]. In this work, reflection-coefficient data were collected at the Shallow Water Acoustic Measurement Instrument (SWAMI) and Piston Core 52 (PC52) sites within the New England Mud Patch area.…”

Section: Scbexmentioning

confidence: 99%

“…where U is the column-eigenvector matrix of the model covariance matrix 20) and W = diag[w i ] is the eigenvalue matrix, with w i representing the variance projected along eigenvector u i (i.e., the variance of PC parameterm i ). PC parameters are perturbed individually, with the perturbation form i drawn from a Cauchy proposal distribution with scale factor w i , and the perturbed models rotated back to physical space for likelihood evaluation.…”

Section: Trans-dimensional Bayesian Formulationmentioning

confidence: 99%

Bayesian geoacoustic inversion of seabed reflection data at the New England mud patch

Belcourt

Dosso

Holland

et al. 2017

The Journal of the Acoustical Society of America

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This thesis presents Bayesian geoacoustic inversion of seabed reflection-coefficient data as part of the U.S. Office of Naval Research Seabed Characterization Experiment 2017 at the New England Mud Patch. First, a linearized, ray-based Bayesian inversion of acoustic arrival times is carried out for high-precision estimation of experiment geometry and uncertainties, representing an important first step to inferring seabed properties using geoacoustic inversion methods such as reflection inversion. The highprecision estimates for source-receiver ranges, source depths, receiver depths, and water depths at reflection points along the survey track are used to calculate grazing angles, with angle uncertainties computed using Monte Carlo methods. The experiment geometry uncertainties are obtained using analytic linearized estimates, and verified with nonlinear analysis. Second, a trans-dimensional (trans-D) Bayesian inversion of reflection-coefficient data is carried out for geoacoustic parameters and uncertainties of fine-grained/cohesive sediments. The trans-D inversion samples probabilistically over an unknown number of seabed interfaces and the parameters of a zeroth-or first-order autoregressive error model. The numerical method of parallel tempering reversible jump Markov-chain Monte Carlo sampling is employed. Spherical-wave reflection coefficient modelling is applied using plane-wave decomposition in the Sommerfeld integral. The inversion provides marginal posterior probability profiles for Buckingham's viscous grain-shearing parameters: porosity, grain-to-grain compressional modulus, material exponent, and compressional viscoelastic time constant as a function of depth in the sediment. These parameters are used to compute dispersion relationships for each layer in the model, providing marginal posterior probability profiles for compressional-wave velocity and attenuation at different frequencies, as well as density. The geoacoustic inversion results are compared to independent mea-Far better an approximate answer to the right question, which is often vague, than an exact answer to the wrong question, which can always be made precise.

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Effect of Shear on Modal Arrival Times

Potty

Miller

2020

IEEE J. Oceanic Eng.

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Preliminary characterization of surficial sediment acoustic properties and infauna in the New England Mud Patch

Cited by 3 publications

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Measurement of Sound Speed in Fine-Grained Sediments During the Seabed Characterization Experiment

Measurement of Sound Speed in Fine-Grained Sediments During the Seabed Characterization Experiment

Bayesian geoacoustic inversion of seabed reflection data at the New England mud patch

Effect of Shear on Modal Arrival Times

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