Sound Propagation Around Underwater Seamounts

Sound Propagation Around Underwater Seamounts
Author: Joseph J. Sikora (III.)
Publisher:
Total Pages: 50
Release: 2005
Genre: Seamounts
ISBN:

This thesis develops and utilizes a method for analyzing data from the North Pacific Acoustic Laboratory's (NPAL) Basin Acoustic Seamount Scattering Experiment (BASSEX). BASSEX was designed to provide data to support the development of analytical techniques and methods which improve the understanding of sound propagation around underwater seamounts. The depth-dependent sound velocity profile of typical ocean waveguides force sound to travel in convergence zones about a minimum sound speed depth. This ducted nature of the ocean makes modeling the acoustic field around seamounts particularly challenging, compared to an isovelocity medium. The conical shape of seamounts also adds to the complexity of the scatter field. It is important to the U.S. Navy to understand how sound is diffracted around this type of topographic feature. Underwater seamounts can be used to conceal submarines by absorbing and scattering the sound they emit. BASSEX measurements have characterized the size and shape of the forward scatter field around the Kermit-Roosevelt Seamount in the Pacific Ocean. Kermit-Roosevelt is a large, conical seamount which shoals close to the minimum sound speed depth, making it ideal for study. Acoustic sources, including M-sequence and linear frequency-modulated sources, were stationed around the seamount at megameter ranges. A hydrophone array was towed around the seamount to locations which allowed measurement of the perturbation zone. Results from the method developed in this thesis show that the size and shape of the perturbation zone measured coincides with theoretical and experimental results derived in previous work.

Sound Propagation Around Underwater Seamounts

Sound Propagation Around Underwater Seamounts
Author:
Publisher:
Total Pages:
Release: 2005
Genre:
ISBN:

Submitted in partial fulfillment of the requirements for Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2005.

Long-Range Sound Propagation Across Atlantic Ocean Seamounts: Implications for Ambient Noise

Long-Range Sound Propagation Across Atlantic Ocean Seamounts: Implications for Ambient Noise
Author: P. D. Koenigs
Publisher:
Total Pages: 16
Release: 1981
Genre:
ISBN:

A low frequency (50-800 Hz) sound-propagation experiment was conducted along a 1400-km path running eastward from Bermuda toward the Mid-Atlantic Ridge. SUS charges were detonated at depths of 18, 154, 615, and 1230 m. The receiver was located at the axis of the deep sound channel (125 m) at a maximum range of 1300 km. The acoustic path crossed several seamounts of the Corner Seamount Group. The highest of these peaks rose to the sound axis. This paper presents the relative enhancement of signal level of SOFAR propagation due to these seamounts as a function of source depth and frequency. The enhancement was minimal for the 1230-m shots, while the greatest enhnacement occurred for the 18-m shots at the 50-Hz filter band. This implies these seamounts and other topographic features such as the mid-Atlantic Ridge can significantly increase the coupling of low-frequency ship-generated noise into the deep sound channel. (Author).

Forward Sound Propagation Around Seamounts

Forward Sound Propagation Around Seamounts
Author:
Publisher:
Total Pages:
Release: 2006
Genre:
ISBN:

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2009.

Fundamentals of Ocean Acoustics

Fundamentals of Ocean Acoustics
Author: L.M. Brekhovskikh
Publisher: Springer Science & Business Media
Total Pages: 289
Release: 2006-04-10
Genre: Science
ISBN: 0387216553

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 Acoustics

Ocean Acoustics
Author: J.A. DeSanto
Publisher: Springer Science & Business Media
Total Pages: 295
Release: 2013-11-11
Genre: Science
ISBN: 3642812945

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.

Sound Propagation through the Stochastic Ocean

Sound Propagation through the Stochastic Ocean
Author: John A. Colosi
Publisher: Cambridge University Press
Total Pages: 443
Release: 2016-06-20
Genre: Mathematics
ISBN: 1107072344

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

Underwater Acoustic Modelling and Simulation, Third Edition

Underwater Acoustic Modelling and Simulation, Third Edition
Author: P.C. Etter
Publisher: CRC Press
Total Pages: 447
Release: 2003-12-08
Genre: Technology & Engineering
ISBN: 0203417658

Underwater Acoustic Modeling and Simulation examines the translation of our physical understanding of sound in the sea into mathematical models that can simulate acoustic propagation, noise and reverberation in the ocean. These models are used in a variety of research and operational applications to predict and diagnose the performance of complex sonar systems operating in the undersea environment. Previous editions of the book have provided invaluable guidance to sonar technologists, acoustical oceanographers and applied mathematicians in the selection and application of underwater acoustic models. Now that simulation is fast becoming an accurate, efficient and economical alternative to field-testing and at-sea training, this new edition will also provide useful guidance to systems engineers and operations analysts interested in simulating sonar performance. Guidelines for selecting and using available propagation, noise and reverberation models are highlighted. Specific examples of each type of model are discussed to illustrate model formulations, assumptions and algorithm efficiency. Instructive case studies demonstrate applications in sonar simulation.