Inversion for the compressional wave speed profile of the bottom from synthetic aperture experiments conducted in the Hudson Canyon area

Rajan, Subramaniam D.; Doutt, James A.; Carey, William M.

doi:10.1109/48.701190

Cited by 19 publications

(7 citation statements)

References 16 publications

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“…This environment is known for the presence of nonlinear internal waves in the water column and high spatial variability of the seabed properties and has been a site of intense scientific interest. [1][2][3] Despite the variability of the seabed, there are prominent features that persist over large areas of the shelf; an example being the "R" reflector, a prominent shallow subsurface seismic reflector that varies in depth with location on the shelf. 4 SW06 is unique in the degree to which high resolution oceanographic measurements were made for support and interpretation of acoustic measurements and results.…”

Section: Introductionmentioning

confidence: 99%

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

Ballard

Becker

2008

The Journal of the Acoustical Society of America

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This paper presents results of a range-independent perturbative inverse approach applied to data from the Shallow Water Experiment 2006. The inversion technique is based on a linearized relationship between sound speed in the sediment and modal eigenvalues. Horizontal wave numbers were estimated from data collected from two distinct source/receiver tracks oriented along and across the shelf. The specific inversion algorithm used is based on qualitative regularization and uses known information about the environment to constrain the solution. Locations of the R reflector and other layering information are used as a priori information for the inversion to emphasize the layered structure of the sediment.

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Section: Introductionmentioning

confidence: 99%

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

Ballard

Becker

2008

The Journal of the Acoustical Society of America

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“…The extracted modes are not sensitive enough to changes in density, attenuation or to any parameters in the second layer to give reasonable estimates of those values. 5,8,9 In summary, the mode extraction technique works well if the VLA samples the water column well and the sources either cover a sufficient range extent or are uncorrelated, as in the case of ambient noise. The acoustic source need not be controlled: its depth, the phase of its tonals, and its precise track do not need to be known.…”

Section: Figure 2 Extracted Modes (Circles) At (A) 150 Hz and (B) 30mentioning

confidence: 99%

Geoacoustic Inversion Using Vertical Line Array Data

Westwood¹,

Neilsen²

2000

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The long-term goal of this work is to develop a method to extract depth-dependent normal modes and to invert for the acoustic parameters of the ocean and ocean bottom using acoustic data measured on a vertical line array. Funding from this grant was also used to improve, maintain, and distribute a stateof-the-art acoustic normal mode model. OBJECTIVES The objectives of the FY00 work were to apply the mode extraction and geoacoustic inversion techniques developed in previous years under ONR funding to measured data and evaluate the strengths and limitations of the methods. APPROACH The technical approach for the geoacoustic inversion method being investigated is (1) to use measured data on a vertical line array (VLA) to extract the depth-dependent mode functions of the environment, and (2) to invert for the environmental parameters by using a non-linear least squares technique for finding the best match between extracted and modeled mode functions. The approach for evaluating the usefulness of the method is to apply the method to the ACT-II data measured in the Hudson Canyon area. This work was carried out by Tracianne Neilsen as her Ph.D. dissertation topic in the Physics Department at the University of Texas at Austin, under the supervision of Evan Westwood. A more detailed description of the technical approach is given below. The required experimental setup for the mode extraction method consists of a source of opportunity moving in the vicinity of a VLA. The time-dependent, single-frequency pressure field measured on the VLA may be viewed as a matrix of pressures versus receiver depth and source-receiver range. A singular value decomposition (SVD) is performed on the pressure matrix. Under certain conditions, it may be shown, using the standard normal mode expression for the pressure field, that the resulting eigenvectors correspond to the depth-dependent normal mode functions of the waveguide. We refer to this procedure as mode extraction.

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“…[16][17][18][19][20][21] Similar waveguide Doppler modeling has been used in narrowband synthetic aperture modal inverse methods. 13,14,22,23 Other moving source or receiver inversion methods 4-6 mitigated Doppler effects in the received signal instead of the forward model, which may result in residual errors.…”

Section: Introductionmentioning

confidence: 99%

Broadband synthetic aperture geoacoustic inversion

Tan

Gerstoft²,

Yardim³

et al. 2013

The Journal of the Acoustical Society of America

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A typical geoacoustic inversion procedure involves powerful source transmissions received on a large-aperture receiver array. A more practical approach is to use a single moving source and/or receiver in a low signal to noise ratio (SNR) setting. This paper uses single-receiver, broadband, frequency coherent matched-field inversion and exploits coherently repeated transmissions to improve estimation of the geoacoustic parameters. The long observation time creates a synthetic aperture due to relative source-receiver motion. This approach is illustrated by studying the transmission of multiple linear frequency modulated (LFM) pulses which results in a multi-tonal comb spectrum that is Doppler sensitive. To correlate well with the measured field across a receiver trajectory and to incorporate transmission from a source trajectory, waveguide Doppler and normal mode theory is applied. The method is demonstrated with low SNR, 100-900 Hz LFM pulse data from the Shallow Water 2006 experiment.

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Inversion for the compressional wave speed profile of the bottom from synthetic aperture experiments conducted in the Hudson Canyon area

Cited by 19 publications

References 16 publications

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

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

Geoacoustic Inversion Using Vertical Line Array Data

Broadband synthetic aperture geoacoustic inversion

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