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Author: R. H. Mellen Publisher: ISBN: Category : Languages : en Pages : 36
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: R. H. Mellen Publisher: ISBN: Category : Languages : en Pages : 36
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: Douglas E. Himberger Publisher: ISBN: Category : Ice Languages : en Pages : 23
Book Description
The report contains a collection of titles and abstracts of papers published and under consideration, relative to reflectivity from ice cover.
Author: Herman Medwin Publisher: Academic Press ISBN: 0080532160 Category : Science Languages : en Pages : 739
Book Description
The developments in the field of ocean acoustics over recent years make this book an important reference for specialists in acoustics, oceanography, marine biology, and related fields. Fundamentals of Acoustical Oceanography also encourages a new generation of scientists, engineers, and entrepreneurs to apply the modern methods of acoustical physics to probe the unknown sea. The book is an authoritative, modern text with examples and exercises. It contains techniques to solve the direct problems, solutions of inverse problems, and an extensive bibliography from the earliest use of sound in the sea to present references.Written by internationally recognized scientists, the book provides background to measure ocean parameters and processes, find life and objects in the sea, communicate underwater, and survey the boundaries of the sea. Fundamentals of Acoustical Oceanography explains principles of underwater sound propagation, and describes how both actively probing sonars and passively listening hydrophones can reveal what the eye cannot see over vast ranges of the turbid ocean. This book demonstrates how to use acoustical remote sensing, variations in sound transmission, in situ acoustical measurements, and computer and laboratory models to identify the physical and biological parameters and processes in the sea.* Offers an integrated, modern approach to passive and active underwater acoustics* Contains many examples of laboratory scale models of ocean-acoustic environments, as well as descriptions of experiments at sea* Covers remote sensing of marine life and the seafloor* Includes signal processing of ocean sounds, physical and biological noises at sea, and inversions* resents sound sources, receivers, and calibration* Explains high intensities; explosive waves, parametric sources, cavitation, shock waves, and streaming* Covers microbubbles from breaking waves, rainfall, dispersion, and attenuation* Describes sound propagation along ray paths and caustics* Presents sound transmissions and normal mode methods in ocean waveguides
Author: R. H. Mellen
Author: R. H. Mellen
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Author: Michael Hilmer
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Author: Douglas E. Himberger
Author: Smithsonian Science Information Exchange
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Author: J. Robert Fricke
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Author: Herman Medwin