Examination of three-dimensional effects using a propagation model with azimuth-coupling capability (FOR3D)

Lee, Ding; Botseas, George; Siegmann, William L.

doi:10.1121/1.402856

Cited by 70 publications

(38 citation statements)

References 9 publications

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“…[1][2][3][4][5][6][7] These models have the potential to be very accurate, but comparisons between data taken at sea and numerical predictions often suffer because of insufficient environmental inputs to the numerical model. This is already a problem for two-dimensional (2D) data-model comparisons and is likely to be a perpetual problem when trying to employ 3D numerical models to describe experimental data.…”

Section: Approachmentioning

confidence: 99%

Three-Dimensional Scale-Model Tank Experiment of the Hudson Canyon Region

Sagers¹

2013

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The long-term scientific goal of this project is to advance understanding of three-dimensional (3D) acoustic propagation in range-dependent ocean waveguides by studying propagation in a scale-model laboratory environment. OBJECTIVESThe objective of this work is to generate high quality acoustic data, measured in the laboratory, that will (1) provide a benchmark standard for 3D numerical models currently being developed, (2) allow researchers to carefully investigate 3D acoustic propagation in a controlled waveguide, and (3) assist ONR in planning for future experiments in ocean environments with slopes and canyons. APPROACHThe development of fully 3D numerical acoustic propagation models is an area of ongoing research. [1][2][3][4][5][6][7] These models have the potential to be very accurate, but comparisons between data taken at sea and numerical predictions often suffer because of insufficient environmental inputs to the numerical model. This is already a problem for two-dimensional (2D) data-model comparisons and is likely to be a perpetual problem when trying to employ 3D numerical models to describe experimental data.An alternative way to provide benchmark-quality data for numerical models is to conduct physical scale-model laboratory experiments. Scale-model experiments permit tight control over many of the variables affecting acoustic propagation, such as water temperature, bathymetry, source/receiver geometry, surface and seafloor roughness, and the geoacoustic properties of the modeled seafloor. Control over these variables allow for precise observation of 3D acoustic propagation effects such as horizontal refraction, shadow zones, multiple mode arrivals, and intra-mode interference.Much of the prior work in scale-model experiments has employed flat or sloping bottoms or random rough surfaces. [8][9][10][11][12][13][14][15] While these experiments have been useful for their intended purpose, they represent idealistic bathymetries that are not found in the ocean. The approach employed in this work is to use 1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.

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Section: Approachmentioning

confidence: 99%

Three-Dimensional Scale-Model Tank Experiment of the Hudson Canyon Region

Sagers¹

2013

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“…Three-dimensional (3D) PE codes have also been developed [13][14][15][16][17]; however, the applications have been limited to shallow water and/or a short range problem because of the extensive computational demand. To consider 3D effects properly, the arc length between two adjacent vertical sections should be less than a quarter of wavelength.…”

Section: Three-dimensional Spectral Coupled-mode Model Vs Threedimenmentioning

confidence: 99%

Forward sound propagation around seamounts : application of acoustic models to the Kermit-Roosevelt and Elvis seamounts

Kim¹

2009

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The Basin Acoustic Seamount Scattering Experiment (BASSEX) of 2004 was conducted to measure forward-scattering around the Kermit-Roosevelt Seamount Complex in the Northeast Pacific. The BASSEX experiment was focused on the bathymetric effects on acoustic propagation, in particular, on direct blockage, horizontal refraction, diffraction, and scattering by the seamounts. A towed hydrophone array, with 64 sensors cut for 250Hz (3m spacing), was used to measure the signals transmitted from the aforementioned broadband sources at many locations around the Kermit-Roosevelt and Elvis seamounts. Utilizing the measured broadband signals from the towed array, the size of the shadow zone was obtained. The measured data in the BASSEX experiment strongly support the understanding of the complicated phenomena of sound propagation around the seamounts. In addition, the experimental data could be used to validate current 2D and 3D theoretical models and develop new models to properly realize the sound propagation with such complicated phenomena.In this thesis, the reconciliation between the measured pulse arrivals from the BASSEX experiment and various two-dimensional (2D) and three-dimensional (3D) theoretical models is carried out to investigate the physical characteristics of the sound propagation around seamounts: First, the 2D Parabolic Equation (PE) model and the 2D ray tracing model are used to reconcile each ray arrival with the BASSEX experiment in terms of arrival time and grazing angle. We construct a sound speed field database based on the sound speed profiles from the BASSEX experiment, World Ocean Atlas (WOA)2005, and CTD casts using the objective analysis.Second, 3D broadband sound propagation around a conical seamount is 4 investigated numerically using the 3D spectral coupled-mode model (W. Luo, PhD Thesis, MIT, 2007). Since the calculation of 3D broadband pulses with the spectral coupledmode model requires extensive computation time, a parallel program is developed with a clustered computing system to obtain results in reasonable time. The validation of the 3D spectral coupled-mode model is performed by a series of comparisons between the various 2D and 3D models for a shallow-water waveguide. The Kermit-Roosevelt seamount is modeled by a simple conical seamount for the 3D model. The computed 3D broadband pulses for the modeled conical seamount are compared with those from the BASSEX experiment and the 2D PE simulation.Through this analysis, we examine the limit of the application of the sound propagation models and improve the efficiency of the 3D sound propagation model using parallel computing to obtain a broadband pulse in a reasonable amount of time.

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“…[9][10][11][12][13][14][15][16] In this work, a normal mode approach is applied. The field decomposition into modal amplitudes provides insight into the effects of environmental inhomogeneities on the acoustic field.…”

Section: Theorymentioning

confidence: 99%

Horizontal refraction of propagating sound due to seafloor scours over a range-dependent layered bottom on the New Jersey shelf

Ballard

Lin

Lynch

2012

The Journal of the Acoustical Society of America

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Three-dimensional propagation effects of low frequency sound from 100 to 400 Hz caused by seafloor topography and range-dependent bottom structure over a 20 km range along the New Jersey shelf are investigated using a hybrid modeling approach. Normal modes are used in the vertical dimension, and a parabolic-equation approximate model is applied to solve the horizontal refraction equation. Examination of modal amplitudes demonstrates the effect of environmental range dependence on modes trapped in the water column, modes interacting with the bottom, and modes trapped in the bottom. Using normal mode ray tracing, topographic features responsible for threedimensional effects of horizontal refraction and focusing are identified. These effects are observed in the measurements from the Shallow Water 2006 experiment. Specifically, signals from a pair of fixed sources recorded on a horizontal line array sitting on the seafloor show an intensification caused by horizontal focusing due to the seabed topography of 4 dB along the array.

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Examination of three-dimensional effects using a propagation model with azimuth-coupling capability (FOR3D)

Cited by 70 publications

References 9 publications

Three-Dimensional Scale-Model Tank Experiment of the Hudson Canyon Region

Three-Dimensional Scale-Model Tank Experiment of the Hudson Canyon Region

Forward sound propagation around seamounts : application of acoustic models to the Kermit-Roosevelt and Elvis seamounts

Horizontal refraction of propagating sound due to seafloor scours over a range-dependent layered bottom on the New Jersey shelf

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