Geoacoustic inversion on the New Jersey Margin: Along and across the shelf

Ballard, Megan S.; Becker, Kyle M.

doi:10.1121/1.2963095

Cited by 15 publications

(17 citation statements)

References 13 publications

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“…Using the wave number estimates at each range as input to a linear inversion algorithm based on qualitative regularization, local estimates of the depth dependent sound speed profile in the sediment were obtained. These results are an improvement to range-independent result reported recently [7] where the low-speed layer was not resolved. A simplified model representing sediment sound speed as a function of depth and range for a track with an East-West orientation, oblique to the shelf slope, is illustrated in the bottom-left panel of Fig.…”

Section: Fig 2 Geoacoustic Inversion Was Applied To Data Collected Asupporting

confidence: 65%

Accounting for Ocean and Seabed Variability in Oceanic Waveguide Parameter Estimation

Becker

2009

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LONG-TERM GOALSThe long-term objective of this work is to develop methods for rapid assessment of seabed variability combined with detailed localized geoacoustic inversions to characterize the bottom for shallow-water environments. Consideration is given to spatial and temporal variability of water column properties common to shallow-water environments and their impact on inversion results. Advances made in the work will contribute to development of unified ocean/ seabed/ acoustic models and improved prediction capabilities for USW tactical decision aids.

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Section: Fig 2 Geoacoustic Inversion Was Applied To Data Collected Asupporting

confidence: 65%

Accounting for Ocean and Seabed Variability in Oceanic Waveguide Parameter Estimation

Becker

2009

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“…Application of nonlinear spectral estimation techniques such as autoregression make it possible to shorten the range aperture while retaining wave number resolution. 20 The autoregressive estimator is an effective tool; it has been successfully applied to a number of previous data sets for wave number estimation, 14,27 and is used in this work.…”

Section: A Perturbative Inversionmentioning

confidence: 99%

Inversion for range-dependent water column sound speed profiles on the New Jersey shelf using a linearized perturbative method

Ballard

Becker

2010

The Journal of the Acoustical Society of America

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The environment of the New Jersey shelf is characterized by high spatial and temporal variability of water column properties caused by intrusions of warm, salty water from the continental slope. These intrusions cause fluctuations in the water column sound speed profile which can have significant effects on acoustic propagation in shallow water. In this work, a linearized perturbative inverse technique is applied to estimate range-dependent water column sound speed profiles. This method utilizes estimates of horizontal wave numbers to determine sound speed as a function of depth. This technique is appropriate for the range-dependent shallow-water environment as horizontal wave numbers can be measured semilocally (1-2 km aperture) and their values are a direct measurement of the local environmental parameters. Difficulty is encountered in application of the perturbative inverse technique because the wave number data are insensitive to some portions of the waveguide and, as a result, the solution can deviate wildly from true values. This issue is addressed by application of approximate equality constraints which force the solution to be close to likely values at prescribed locations.

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“…All the midfrequency inversions (Choi et al [10], Jiang et al MF [18] and [19], Turgut [23], Yang et al [11]) were performed within 400 m of the MORAY array, depicted by a green square. Most of the low-frequency inversions considered signals recorded on the MPL VLA 1 array (Bonnel et al [15] and [16], Duan et al [17], Huang et al [14], Jiang and Chapman LF [12] and [13]), except Ballard et al [20] and [21] thin layer of sand (∼6 m) covered the underlying outer shelf wedge sediment. Two L-shaped vertical/horizontal arrays of the Applied Research Laboratory at University of Texas, Austin, TX, USA, were deployed at locations about 20 km apart on the sand ridge, and were used to collect both continuous wave (CW) and broadband impulsive data during a three week period.…”

Section: B Sw06 Experimental Sitementioning

confidence: 99%

An Experimental Benchmark for Geoacoustic Inversion Methods

Bonnel

Pecknold

Hines³

et al. 2021

IEEE J. Oceanic Eng.

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Over the past 25 years, there has been significant research activity in development and application of methods for inverting acoustical field data to estimate parameters of geoacoustic models of the ocean bottom. Although the performance of various geoacoustic inversion methods has been benchmarked on simulated data, their performance with experimental data remains an open question. This article constitutes the first attempt of an experimental benchmark of geoacoustic inversion methods. To do so, the article focuses on data from experiments carried out at a common site during the Shallow Water 2006 (SW06) experiment. The contribution of the article is twofold. First, the article provides an overview of experimental inversion methods and results obtained with SW06 data. Second, the article proposes and uses quantitative metrics to assess the experimental performance of inversion methods. From a sonar performance point of view, the benchmark shows that no particular geoacoustic inversion method is definitely better than any other of the ones that were tested. All the inversion methods generated adequate sound-speed profiles, but only a few methods estimated attenuation and density. Also, acoustical field prediction performance drastically reduces with range for all geoacoustic models, and this performance loss dominates over intermodel variability. Overall, the benchmark covers the two main objectives of geoacoustic inversion: obtaining geophysical information about the seabed, and/or predicting acoustic propagation in a given area. Index Terms-Benchmark, geoacoustic inversion, ShallowWater 2006 (SW06), underwater acoustics. I. INTRODUCTIONF OR the past three decades there has been renewed focus among researchers in underwater acoustics on sound propagation in shallow water. The traditional wisdom about shallow water acoustics holds that the interaction of sound with the ocean bottom has considerable impact on the acoustical field in the water. Since sound sources in shallow water are relatively close to the seafloor interface, sound reflected from the seafloor and subbottom interfaces or refracted within the bottom and returned

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Geoacoustic inversion on the New Jersey Margin: Along and across the shelf

Cited by 15 publications

References 13 publications

Accounting for Ocean and Seabed Variability in Oceanic Waveguide Parameter Estimation

Accounting for Ocean and Seabed Variability in Oceanic Waveguide Parameter Estimation

Inversion for range-dependent water column sound speed profiles on the New Jersey shelf using a linearized perturbative method

An Experimental Benchmark for Geoacoustic Inversion Methods

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