Reverberation From Deep Scattering Layers in the Western North Atlantic PDF Download

Author: Naval Research Establishment (Canada)
Publisher:
ISBN:
Category :
Languages : en
Pages : 35

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Author: G. Brooke Farquhar
Publisher:
ISBN:
Category : Acoustic phenomena in nature
Languages : en
Pages : 652

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Author: United States. Naval Oceanographic Office
Publisher:
ISBN:
Category : Echo scattering layers
Languages : en
Pages : 72

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Author: Charles L Brown (Jr)
Publisher:
ISBN:
Category :
Languages : en
Pages : 33

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Deep scattering layers (DSL) present formidable interference to underwater acoustic systems in large areas of the Atlantic and Pacific Ocean. This interference is due to volume reverberation from the DSL and appears to be caused primarily by the backscattering of sound from fish possessing gas-filled swim-bladders. From a deep research vehicle, samples of organisms were taken successively below, in, and above the DSL in an area of the western North Atlantic during August 1966. Mere numbers of fish did not appear significant in determining the acoustic properties of the DSL. From results of the biological sampling, scattering strengths have been calculated for single frequencies of 4 kHz and 12 kHz, as well as for several frequency bands. The results near 12 kHz agree reasonably well with experimental values for similar areas, but results near 4 kHz are somewhat lower than those of other investigations. (Author).

Author: United States. Navy Department
Publisher:
ISBN:
Category :
Languages : en
Pages : 656

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Author: G. Brooke Farquhar
Publisher:
ISBN:
Category : Oceanography
Languages : en
Pages : 652

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Author: G. B. Farquhar
Publisher:
ISBN:
Category :
Languages : en
Pages : 18

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Preliminary results are presented of bio-acoustic investigations of sound scattering layers in the subtropical western North Atlantic. Methods of data collection and analysis are briefly described. Scattering strengths over a range of frequencies from 1.6 to 20.0 kc/s are presented, as well as the variation of scattering strengths over sunrise and sunset periods, as a function of frequency. Patterns of scattering at 12 kc/s, based on echosounder records, are described briefly, and results are give of cursory examination of biological samples. Scattering strength data are compared with similar data from an area near Bermuda, and the relationship of the differences to the relative abundance of marine life in the two areas is briefly discussed. (Author).

Author: United States. Naval Oceanographic Office
Publisher:
ISBN:
Category : Echo scattering layers
Languages : en
Pages : 652

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Author: Antony Joseph
Publisher: Newnes
ISBN: 0123914280
Category : Science
Languages : en
Pages : 447

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Book Description
Measuring Ocean Currents: Tools, Technologies, and Data covers all major aspects of ocean current measurements in view of the implications of ocean currents on changing climate, increasing pollution levels, and offshore engineering activities. Although more than 70% of the Earth is covered by ocean, there is limited information on the countless fine- to large-scale water motions taking place within them. This book fills that information gap as the first work that summarizes the state-of-the-art methods and instruments used for surface, subsurface, and abyssal ocean current measurements. Readers of this book will find a wealth of information on Lagrangian measurements, horizontal mapping, imaging, Eulerian measurements, and vertical profiling techniques. In addition, the book describes modern technologies for remote measurement of ocean currents and their signatures, including HF Doppler radar systems, satellite-borne sensors, ocean acoustic tomography, and more. Crucial aspects of ocean currents are described in detail as well, including dispersion of effluents discharged into the sea and transport of beneficial materials—as well as environmentally hazardous materials—from one region to another. The book highlights several important practical applications, showing how measurements relate to climate change and pollution levels, how they affect coastal and offshore engineering activities, and how they can aid in tsunami detection. - Coverage of measurement, mapping and profiling techniques - Descriptions of technologies for remote measurement of ocean currents and their signatures - Reviews crucial aspects of ocean currents, including special emphasis on the planet-spanning thermohaline circulation, known as the ocean's "conveyor belt," and its crucial role in climate change

Author: Jean-Paul Marage
Publisher: John Wiley & Sons
ISBN: 1118600657
Category : Technology & Engineering
Languages : en
Pages : 590

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Book Description
Sonar and Underwater Acoustics brings together all the concepts necessary for designers and users of sonar systems. Unlike other books on this subject, which are often too specialized, this book is accessible to a wider audience. The first part focuses on the acoustic environment, antenna structures, and electric acoustic interface. The latter provides knowledge required to design, as well as the development and implementation of chain processes for an active sonar from the conditioning input to output processing. The reader will find a comprehensive range of all problems encountered in underwater acoustics for a sonar application, from physical phenomena governing the environment and the corresponding constraints, through to the technical definition of transducers and antennas, and the types of signal processing involved. In one section, measures in underwater acoustics are also proposed.