Arctic Acoustic Propagation Model with Ice Scattering PDF Download

Author: D. F. Gordon
Publisher:
ISBN:
Category :
Languages : en
Pages : 56

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Book Description
An underwater sound propagation program has been adapted to Arctic use. The program enables computation of the coherent sound field with normal modes and the incoherent surface scattered field by integrating over ray paths from the surface to the source and receiver. For Arctic use, ice scattering and ice loss functions have been developed by comparing computed losses with Arctic propagation loss data. The sensitivity of the computed losses to the form of the scattering function is determined for one frequency. A difference in ice loss between summer and winter is hypothesized, but the data are insufficient to check the hypothesis. (Author).

Author: R. R. Greene
Publisher:
ISBN:
Category :
Languages : en
Pages : 41

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Book Description
Acoustic propagation in the Arctic is intimately related to the structure of surface pack ice. In this paper, reflection loss and transmission loss are calculated based upon statistical models of ice roughness. Statistical models of ice ridges are introduced and techniques for estimating the roughness spectrum of ridged surfaces are developed. Next, a model for estimating the mean reflection loss is introduced. The reflection loss formulas are based on the statistical models for roughness. Transmission loss calculations using High-Angle parabolic equation (ARCHAPE) in a simulated Arctic environment are compared with data. The results demonstrate that rough surface scattering from random-depth ice keel structures can account for the observed rate of transmission loss in the Arctic. Keywords include: Acoustic Scattering, and Propagation loss.

Author: P.C. Etter
Publisher: CRC Press
ISBN: 0203417658
Category : Technology & Engineering
Languages : en
Pages : 447

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Book Description
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.

Author: R. H. Mellen
Publisher:
ISBN:
Category :
Languages : en
Pages : 36

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Book Description
Underwater acoustic propagation in the Arctic Ocean is characterized by a refractive surface-channel with a rough boundary. Acoustic scattering estimates, based on free-surface theory, have proven low by more than a factor of two in forward-scatter loss and low by 20 dB or more in backscatter strength. Failure to account for either attenuation or backscattering indicates that impedance effects must be involved. The ice layer is modeled as a uniform elastic solid. Perturbation analysis shows scattering from slopes as well as displacements. Displacements produce piston-like reradiation in addition to the usual vertical-dipole type associated with free surfaces. The 'rocking' horizontal dipole produced by slopes is evidently a significant mechanism at the lower frequencies. However, estimates of both attenuation and backscatter strength are much too low compared with experimental data. Keywords: Acoustic attenuation; Ice-water interface slope; Acoustic reflectivity; Underice roughness, Acoustic velocity; Low-frequency.

Author: Paul C. Etter
Publisher: CRC Press
ISBN: 1351831984
Category : Technology & Engineering
Languages : en
Pages : 557

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Book Description
Underwater Acoustic Modeling and Simulation, Fourth Edition continues to provide the most authoritative overview of currently available propagation, noise, reverberation, and sonar-performance models. This fourth edition of a bestseller discusses the fundamental processes involved in simulating the performance of underwater acoustic systems and emphasizes the importance of applying the proper modeling resources to simulate the behavior of sound in virtual ocean environments. New to the Fourth Edition Extensive new material that addresses recent advances in inverse techniques and marine-mammal protection Problem sets in each chapter Updated and expanded inventories of available models Designed for readers with an understanding of underwater acoustics but who are unfamiliar with the various aspects of modeling, the book includes sufficient mathematical derivations to demonstrate model formulations and provides guidelines for selecting and using the models. Examples of each type of model illustrate model formulations, model assumptions, and algorithm efficiency. Simulation case studies are also included to demonstrate practical applications. Providing a thorough source of information on modeling resources, this book examines the translation of our physical understanding of sound in the sea into mathematical models that simulate acoustic propagation, noise, and reverberation in the ocean. The text shows how these models are used to predict and diagnose the performance of complex sonar systems operating in the undersea environment.

Author: P.C. Etter
Publisher: CRC Press
ISBN: 1482295148
Category : Technology & Engineering
Languages : en
Pages : 447

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Book Description
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 s

Author: P.C. Etter
Publisher: CRC Press
ISBN: 9780419201908
Category : Architecture
Languages : en
Pages : 364

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Book Description
Underwater Acoustic Modeling provides the only comprehensive source on how to translate our physical understanding of sound in the sea into mathematical formulas solvable by computers.

Author: Paul C. Etter
Publisher: CRC Press
ISBN: 1351679716
Category : Technology & Engineering
Languages : en
Pages : 776

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Book Description
This newest edition adds new material to all chapters, especially in mathematical propagation models and special applications and inverse techniques. It has updated environmental-acoustic data in companion tables and core summary tables with the latest underwater acoustic propagation, noise, reverberation, and sonar performance models. Additionally, the text discusses new applications including underwater acoustic networks and channel models, marine-hydrokinetic energy devices, and simulation of anthropogenic sound sources. It further includes instructive case studies to demonstrate applications in sonar simulation.

Author: G. L. Duckworth
Publisher:
ISBN:
Category :
Languages : en
Pages : 14

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Book Description
A single explosive shot at a range of 341.3 km in the Pole Abyssal Plain of the Arctic Ocean is used to assess the components of propagation loss for this region. The acoustic energy propagated between a satellite ice camp and the Fram II ice station in a water column of nearly uniform depth. Much of the observed energy interacted with the upper 200 meters of sediments along a path which was nearly parallel to the Arctic Mid-Ocean Ridge. In addition, the upward refracting sound channel of the Arctic Ocean also caused the observed energy to interact extensively with the ice canopy, which was contiguous over the entire path. The deterministic lateral homogeneity of the bathymetry and sediments, and the statistical lateral homogeneity of the ice canopy in this region allow us to attempt to separate the effects of geometrical spreading, ice surface scattering, and effective sediment compressional wave attenuation. The primary data for this work are observations of the signal from a 25.8 kg explosive charge received on a 24 channel two-dimensional hydrophone array with a 1 km aperture. The data are inadequate to resolve attenuation at depth, but provide an estimate for frequency independent Q of 200 to 300 for the upper 200 meters of the sediments and a dependency of surface scattering on frequency over the 5-50 Hz band. It is shown that partially coherent summation of the surface multipaths is required to predict the observations. (RRH).

Author: J. Potter
Publisher: Springer Science & Business Media
ISBN: 9401133123
Category : Science
Languages : en
Pages : 599

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Book Description
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.