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Ocean Variability & Acoustic Propagation

Author: J. Potter

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 599

ISBN-13: 9401133123

Fifteen years ago NATO organised a conference entitled 'Ocean Acoustic Modelling'. Many of its participants were again present at this variability workshop. One such participant. in concluding his 1975 paper, quoted the following from a 1972 literature survey: ' ... history presents a sad lack of communications between acousticians and oceanographers' Have we done any better in the last 15 years? We believe so, but only moderately. There is still a massive underdeveloped potential for acousticians and oceanographers to make significant progress together. Currently, the two camps talk together insufficiently even to avoid simple misun derstandings. such as those in Table 1. Table 1 Ocsanographic and acoustic jargon (from an idea by Pol/ardi Jargon Oceanographic use Acoustic use dbordB decibar (depth in m) decibel (energy level) PE primitive equations parabolic equations convergence zone converging currents converging rays (downwelling water) (high energy density) front thermohaline front wave, ray or time front speed water current speed sound propagation speed 1 The list goes on.

Ocean Variability

Author: Clare Nadig

Publisher:

Published: 2014

Total Pages:

ISBN-13:

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Acoustic propagation in the ocean is driven by the sound velocity profile, which varies in both space and time. These variations are caused by many phenomena, but on the finestructure (10 meters to 1 kilometer) scale, the dominant forces in most areas of the ocean are internal waves and thermohaline intrusions. Internal waves are gravity waves (similar to surface waves) that propagate beneath the surface by displacing the stratified constant density surfaces. Thermohaline intrusions (also referred to as spice) are variations in temperature and salinity which compensate each other in their effect on density. Although spice features are independent of density and therefore have a very minimal effect on ocean dynamics, they do affect the sound velocity in the water, and therefore can be very important acoustically.This thesis uses data from the Transverse Acoustic Variability Experiment (TAVEX) to study properties of spice in the East China Sea and examine their impact on sound propagation through use of parabolic equation acoustic modeling. A method of separating the effects of internal waves and spice on a sound speed field is presented, followed by several methods of analyzing the form and characteristics of the spice present in the data. Finally, parabolic equation code is used to model acoustic propagation through sound speed fields containing spice, and connections are drawn between the spice contained in a field and its impact on the resulting acoustic field.

Oceanography and Acoustics

Author: Allan R. Robinson

Publisher: American Institute of Physics

Published: 1994

Total Pages: 302

ISBN-13:

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Market: Ocean dynamicists and acousticians. "Useful to scientists or students interested in ocean dynamical modelling, acoustic propagation modelling, and particularly to those interested in the union of these fields (which is likely to be become increasingly important)." Revue de livre With complete chapters contributed by leading authorities, this work offers a comprehensive overview of current combined research in acoustics and oceanography. Following an introduction on ocean variability, acoustic propagation, and coupled models, subsequent chapters present up-to-date coverage of the developing relationship between ocean science and ocean acoustics, including an extensive review of state-of-the-art three-dimensional models.

Fundamentals of Ocean Acoustics

Author: L.M. Brekhovskikh

Publisher: Springer Science & Business Media

Published: 2006-04-10

Total Pages: 289

ISBN-13: 0387216553

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This book provides an up-to-date introduction to the theory of sound propagation in the ocean. The text treats both ray and wave propagation and pays considerable attention to stochastic problems such as the scattering of sound at rough surfaces and random inhomogeneities. An introductory chapter that discusses the basic experimental data complements the following theoretical chapters. New material has been added throughout for this third edition. New topics covered include: - inter-thermocline lenses and their effect on sound fields - weakly divergent bundles of rays - ocean acoustic tomography - coupled modes - sound scattering by anisotropic volume inhomogeneities with fractal spectra - Voronovich's approach to sound scattering from the rough sea surface. In addition, the list of references has been brought up to date and the latest experimental data have been included.

Ocean Acoustic Propagation by Finite Difference Methods

Author: D. Lee

Publisher: Elsevier

Published: 2014-06-28

Total Pages: 134

ISBN-13: 1483295699

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A concise guide to the theory and application of numerical methods for predicting ocean acoustic propagation, also providing an introduction to numerical methods, with an overview of those methods presently in use. An in-depth development of the implicit-finite-difference technique is presented together with bench-mark test examples included to demonstrate its application to realistic ocean environments. Other applications include atmospheric acoustics, plasma physics, quantum mechanics, optics and seismology.

Sound Propagation in the Sea

Author: Robert J. Urick

Publisher:

Published: 1979

Total Pages: 268

ISBN-13:

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Numerical Ocean Acoustic Propagation In Three Dimensions

Author: Ding Lee

Publisher: World Scientific

Published: 1995-12-31

Total Pages: 220

ISBN-13: 9814500291

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This book introduces a comprehensive mathematical formulation of the three-dimensional ocean acoustic propagation problem by means of functional and operator splitting techniques in conjunction with rational function approximations. It presents various numerical solutions of the model equation such as finite difference, alternating direction and preconditioning. The detailed analysis of the concept of 3D, N x 2D and 2D problems is very useful not only mathematically and physically, but also computationally. The inclusion of a complete detailed listing of proven computer codes which have been in use by a number of universities and research organizations worldwide makes this book a valuable reference source. Advanced knowledge of numerical methods, applied mathematics and ocean acoustics is not required to understand this book. It is oriented toward graduate students and research scientists to use for research and application purposes.

Sound Propagation through the Stochastic Ocean

Author: John A. Colosi

Publisher: Cambridge University Press

Published: 2016-06-20

Total Pages: 443

ISBN-13: 1107072344

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In this book, key discoveries in the field of statistical ocean acoustics over the last 35 years are addressed with illustrations from ocean observations.

Acoustic Propagation Through Sound Speed Heterogeneity

Author:

Publisher:

Published: 2009

Total Pages: 4

ISBN-13:

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The goal of this work is to quantitatively understand the effects on low-frequency, long-range ocean acoustic propagation by small-scale variability in the sound speed. These variations are due to internal waves and to "spice", temperature and salinity variations that don't affect the water density.

Ocean Acoustics

Author: J.A. DeSanto

Publisher: Springer Science & Business Media

Published: 2013-11-11

Total Pages: 295

ISBN-13: 3642812945

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This Topics volume is devoted to a study of sound propagation in the ocean. The effect of the interior of the ocean on underwater sound is analogous to the effect of a lens on light. The oceanic lens is related, as in light propagation, to the index of refraction of the medium. The latter is giv~n by the ratio of the sound frequency to the speed of sound in water, typi ca lly about 1500 m s -1. It is the vari ation of the sound speed due to changing temperature, density, salinity, and pres sure in the complex ocean environment which creates the lens effect. Many oceanic processes such as currents, tides, eddies (circulating, translating regions of wa ter), and internal waves (the wave-like structure of the oceanic density variabil ity) contri bute in turn to the changes in sound speed'. The net effect of the ocean lens is to trap and guide sound waves in a channel created by the lens. The trapped sound can then propagate thousands of miles in this oceanic waveguide. In addition to the propagation in the interior of the ocean, sound can propagate into and back out of the ocean bottom as well as scatter from the ocean surface. Just as the sound produced by a loudspeaker in a room is affected by the walls of the room, so the ocean boundaries and the material properties below the ocean bottom are essential ingredients in the problem.