Computational Ocean Acoustics

Jensen, Finn B.; Kuperman, W. A.; Porter, Michael B.; Schmidt, Henrik

doi:10.1007/978-1-4419-8678-8

Cited by 1,312 publications

(976 citation statements)

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“…3e). The intermediate empirical spreading model (15log) underestimated the TL by up tõ 20dB, while the spherical spreading model (20log), which is generally used for deep waters (Jensen et al, 2011), overestimated the TL in the Celtic Sea with a maximum value of~20dB.…”

Section: Differences In Sound Propagation Model Performancementioning

confidence: 99%

Shipping noise in a dynamic sea: a case study of grey seals in the Celtic Sea

Chen

Shapiro

Bennett

et al. 2017

Marine Pollution Bulletin

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Shipping noise is a threat to marine wildlife. Grey seals are benthic foragers, and thus experience acoustic noise throughout the water column, which makes them a good model species for a case study of the potential impacts of shipping noise. We used ship track data from the Celtic Sea, seal track data and a coupled ocean-acoustic modelling system to assess the noise exposure of grey seals along their tracks. It was found that the animals experience step changes in sound levels up to~20dB at a frequency of 125Hz, and~10dB on average over 10 1000Hz when they dive through the thermocline, particularly during summer. Our results showed large seasonal differences in the noise level experienced by the seals. These results reveal the actual noise exposure by the animals and could help in marine spatial planning.

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Section: Differences In Sound Propagation Model Performancementioning

confidence: 99%

Shipping noise in a dynamic sea: a case study of grey seals in the Celtic Sea

Chen

Shapiro

Bennett

et al. 2017

Marine Pollution Bulletin

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“…Note that, in the much simpler 1D case over a flat bottom, where k n = const, the spatial potential would be a combination of φ n (ξ) = exp(±ik n ξ/ ), see e.g. Jensen et al (2011). For a 2HD varying bathymetry, by similarity we look for solutions of the form…”

Section: General Solutionmentioning

confidence: 99%

“…is the pressure produced at a distance r by a source of the same intensity as the bottom disturbance, but in an infinite, homogeneous medium with the ambient density ρ 0 (Jensen et al 2011). …”

Section: Analytical Solution On a Plane Beachmentioning

confidence: 99%

Hydro-acoustic frequencies of the weakly compressible mild-slope equation

Renzi

2016

J. Fluid Mech.

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This draft was prepared using the LaTeX style file belonging to the Journal We present a novel analytical solution for hydro-acoustic waves in a weakly compressible fluid over a slowly varying bottom. Application of a multiple-scale perturbation technique and matched asymptotic analysis leads to a uniform analytical solution of the depthaveraged governing equations in three dimensions. We show that the slow depth variation plays a leading-order effect on the evolution of the normal mode amplitude and direction. This dynamics is much richer than the two-dimensional limit analysed in previous studies.For tsunamigenic disturbances, we show that the hydro-acoustic wave field is made up by longshore trapped and offshore propagating components, which were not explicated in previous work. For a plane beach, we find an exact analytical solution of the model equation in terms of integrals of Bessel functions. Our model offers a physical insight into the evolution of hydro-acoustic waves of interest for the design of tsunami early warning systems.

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“…Even in the case of adiabatic mode propagation, it is expected that this mode 1 energy will experience some redistribution in the water column due to the effective narrowing of the waveguide by the shelfbreak; therefore, it is important to discriminate between energy variation due to adiabatic mode propagation alone and energy variation due to enhanced mode coupling. These differences are examined by calculating the transmission loss (TL) for case ISW-SB using adiabatic mode theory (Jensen et al, 1994) and coupled mode theory, which are shown in Fig. 7.…”

Section: Energy Enhancement Due To Mode Coupling At the Shelfbreakmentioning

confidence: 99%

Enhanced acoustic mode coupling resulting from an internal solitary wave approaching the shelfbreak in the South China Sea

Chiu

Reeder

Chang

et al. 2013

The Journal of the Acoustical Society of America

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Internal waves and bathymetric variation create time-and space-dependent alterations in the ocean acoustic waveguide, and cause subsequent coupling of acoustic energy between propagating normal modes. In this paper, the criterion for adiabatic invariance is extended to the case of an internal solitary wave (ISW) encountering a sloping bathymetry (i.e., continental shelfbreak). Predictions based on the extended criterion for adiabatic invariance are compared to experimental observations from the Asian Seas International Acoustics Experiment. Using a mode 1 starter field, results demonstrate time-dependent coupling of mode 1 energy to higher adjacent modes, followed by abrupt coupling of mode 5-7 energy to nonadjacent modes 8-20, produces enhanced mode coupling and higher received levels downrange of the oceanographic and bathymetric features. Numerical simulations demonstrate that increasing ISW amplitude and seafloor slope enhance the coupling of energy to adjacent and nonadjacent modes. This enhanced coupling is the direct result of the simultaneous influence of the ISW and its proximity to the shelfbreak, and, compared to the individual effect of the ISW or shelfbreak, has the capacity to scatter 2-4 times the amount of acoustic energy from below the thermocline into the upper water column beyond the shelfbreak in realistic environments.

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Computational Ocean Acoustics

Cited by 1,312 publications

References 0 publications

Shipping noise in a dynamic sea: a case study of grey seals in the Celtic Sea

Shipping noise in a dynamic sea: a case study of grey seals in the Celtic Sea

Hydro-acoustic frequencies of the weakly compressible mild-slope equation

Enhanced acoustic mode coupling resulting from an internal solitary wave approaching the shelfbreak in the South China Sea

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