Acoustic Propagation Uncertainty in the Shallow East China Sea

Abbot, Philip; Dyer, Ira; Emerson, Chris

doi:10.1109/joe.2006.875103

Cited by 19 publications

(12 citation statements)

References 10 publications

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“…Although there is no reason to expect the 600 Hz data to agree with the 900 Hz data, due to its smaller timebandwidth product, the OMAS2 600 Hz results are, in fact, consistent with the 900 Hz data. The OMAS1 600 Hz data departs from this, with a r dl15 of 2.5 dB and a r dl5 of 2.0 dB [We use standard deviation a as a measure of the variability of the data about the given means, as discussed in Abbot et al (2006b)]. …”

Section: A Overview Of the Acoustic Datamentioning

confidence: 99%

“…Following this, the acoustic data are examined, with emphasis on the mean and variance of the received field, and on the spatial (azimuthal, as well as translational) dependence of these results. In doing this, we draw on the work presented in Abbot et al (2006b), one of the first attempts to evaluate the isotropy (or lack thereof) of an azimuthally distributed, shallow-water transmission loss (TL) data set. Next, detailed modeling of the data is presented, with the aim being to explain the major features of the data that reflect on azimuthal and translational invariance of the transmission loss.…”

Section: Background/introductionmentioning

confidence: 99%

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On whether azimuthal isotropy and alongshelf translational invariance are present in low-frequency acoustic propagation along the New Jersey shelfbreak

Lynch

Emerson

Abbot

et al. 2012

The Journal of the Acoustical Society of America

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To understand the issues associated with the presence (or lack) of azimuthal isotropy and horizontal (along isobath) invariance of low-frequency (center frequencies of 600 Hz and 900 Hz) acoustic propagation in a shelfbreak environment, a series of experiments were conducted under the Autonomous Wide-Aperture Cluster for Surveillance component of the Shallow Water 2006 experiment. Transmission loss data reported here were from two mobile acoustic sources executing (nearly) circular tracks transmitting to sonobuoy receivers in the circle centers, and from one 12.5 km alongshelf acoustic track. The circle radii were 7.5 km. Data are from September 8, 2006. Details of the acoustic and environmental measurements are presented. Simple analytic and computer models are used to assess the variability expected due to the ocean and seabed conditions encountered. A comparison of model results and data is made, which shows preliminary consistency between the data and the models, but also points towards further work that should be undertaken specifically in enlarging the range and frequency parameter space, and in looking at integrated transmission loss.

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Section: A Overview Of the Acoustic Datamentioning

confidence: 99%

Section: Background/introductionmentioning

confidence: 99%

On whether azimuthal isotropy and alongshelf translational invariance are present in low-frequency acoustic propagation along the New Jersey shelfbreak

Lynch

Emerson

Abbot

et al. 2012

The Journal of the Acoustical Society of America

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“…As discussed above, environmental statistics provide a first look at the environmental variability and can lead to inferences about the acoustic uncertainty. Another method using probability density functions (pdf) and comparing the mean TL (TL) to the standard deviation of TL (oTL) was described in Abbot, Dyer, & Emerson (2006). Dosso has presented a method for determining sensitivity based on an environmental uncertainty distribution (Dosso, 2008).…”

Section: Approachmentioning

confidence: 99%

Environmental analysis and prediction of transmission loss in the region of the New England Shelfbreak

Hornick¹

2009

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A confluence of several coastal oceanographic features creates an acoustically interesting region with high variability along the New England Shelfbreak. Determining the effect of the variability on acoustic propagation is critical for sonar systems. In the Nantucket Shoals area of the Middle Atlantic Bight, two experiments, the New England Shelfbreak Tests (NEST), were conducted in May and June, 2007 and 2008, to study this variability. A comprehensive climatology of the region along with the experimental data provided detailed information about the variability of the water column, particularly the temperature and sound speed fields. Empirical orthogonal function (EOF) analysis of the ocean sound speed field defined a set of perturbations to the background sound speed field for each of the NEST Scanfish surveys.Attenuation due to bottom sediments is the major contributor of transmission loss in the ocean. In shallow water, available propagation paths most often include bottom interaction. Perturbations in the ocean sound speed field can cause changes in the angle of incidence of sound rays with the bottom, which can result in changes to the amount of sound energy lost to the bottom. In lieu of complex transmission loss models, the loss/bounce model provides a simpler way to predict transmission loss changes due to perturbations in the background sound speed field in the ocean. Using an acoustic wavenumber perturbation method, sound speed perturbations, defined by the ocean EOF modes, are translated into a change in the horizontal wavenumber, which in turn changes the modal angle of incidence. The loss/bounce model calculates the loss of sound energy (dB) per bottom bounce over a given distance based on the change in angle of incidence. Evaluated using experimental data from NEST, the loss/bounce model provided accurate predictions of changes to transmission loss due to perturbations of the background sound speed field.

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“…The integrated physical oceanographic measurements with the mobile acoustic source/receiver data on transmission loss is important in providing the field testing of the Predictive Probability of Detection (PPD) methodology developed by Abbot et al (2006). The data will also be used to evaluate uncertainty in the circulation model used by P. Lermusiaux.…”

Section: Impact/applicationsmentioning

confidence: 99%

High-Resolution Hydrographic Surveys Near the Shelfbreak in the East China Sea: Joint Studies with National Taiwan University

Gawarkiewicz

2008

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Acoustic Propagation Uncertainty in the Shallow East China Sea

Cited by 19 publications

References 10 publications

On whether azimuthal isotropy and alongshelf translational invariance are present in low-frequency acoustic propagation along the New Jersey shelfbreak

On whether azimuthal isotropy and alongshelf translational invariance are present in low-frequency acoustic propagation along the New Jersey shelfbreak

Environmental analysis and prediction of transmission loss in the region of the New England Shelfbreak

High-Resolution Hydrographic Surveys Near the Shelfbreak in the East China Sea: Joint Studies with National Taiwan University

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