Sound Scattering from Oceanic Turbulence PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Sound Scattering from Oceanic Turbulence PDF full book. Access full book title Sound Scattering from Oceanic Turbulence by . Download full books in PDF and EPUB format.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Co-located measurements of acoustic backscatter and temperature/velocity microstructure are used to confirm theoretical predictions of sound scatter from oceanic turbulence. The data were collected with a torpedo-shaped vehicle carrying four shear probes and two thermistors on its nose, and forward-looking 44.7 and 307 kilohertz echosounders (mounted 20 centimetres below the turbulence sensors). The vehicle was towed through the stratified turbulence that forms tidally over the lee side of a sill in a British Columbia fjord. Conventional downward-looking echosounder measurements were also made with a 100 kilohertz sounder mounted in the ship's hull. Populations of amphipods, euphausiids, copepods and gastropods were present in the fjord (sampled with 335-micrometre mesh vertical net-hauls) and could be seen in the sounder data. These plankton net-hauls indicated that there were too few zooplankton in the turbulent regions to account for the scattering intensity. At both 44.7 and 307 kilohertz, scatter that is unambiguously correlated with turbulence was observed. Turbulent scatter is much stronger at the higher frequency, illustrating the mportance of salinity microstructure--long neglected in turbulent scattering models--and shedding some light on the form of the turbulent temperature-salinity co-spectrum. The turbulent temperature-salinity co-spectrum has never been measured directly. Although several models have been proposed for the form of the co-spectrum, they all produce unsatisfactory results when applied to the turbulent scattering equations (either predicting negative scattering cross-sections in some density regimes or predicting implausible levels of correlation between temperature and salinity at some scales). A new co-spectrum model is proposed and shown to be not only physically plausible in all density regimes, but also in reasonable agreement with the scattering data. At 307 kilohertz, the backscatter is mostly from salinity microstructure and, depend.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Co-located measurements of acoustic backscatter and temperature/velocity microstructure are used to confirm theoretical predictions of sound scatter from oceanic turbulence. The data were collected with a torpedo-shaped vehicle carrying four shear probes and two thermistors on its nose, and forward-looking 44.7 and 307 kilohertz echosounders (mounted 20 centimetres below the turbulence sensors). The vehicle was towed through the stratified turbulence that forms tidally over the lee side of a sill in a British Columbia fjord. Conventional downward-looking echosounder measurements were also made with a 100 kilohertz sounder mounted in the ship's hull. Populations of amphipods, euphausiids, copepods and gastropods were present in the fjord (sampled with 335-micrometre mesh vertical net-hauls) and could be seen in the sounder data. These plankton net-hauls indicated that there were too few zooplankton in the turbulent regions to account for the scattering intensity. At both 44.7 and 307 kilohertz, scatter that is unambiguously correlated with turbulence was observed. Turbulent scatter is much stronger at the higher frequency, illustrating the mportance of salinity microstructure--long neglected in turbulent scattering models--and shedding some light on the form of the turbulent temperature-salinity co-spectrum. The turbulent temperature-salinity co-spectrum has never been measured directly. Although several models have been proposed for the form of the co-spectrum, they all produce unsatisfactory results when applied to the turbulent scattering equations (either predicting negative scattering cross-sections in some density regimes or predicting implausible levels of correlation between temperature and salinity at some scales). A new co-spectrum model is proposed and shown to be not only physically plausible in all density regimes, but also in reasonable agreement with the scattering data. At 307 kilohertz, the backscatter is mostly from salinity microstructure and, depend.
Author: Tetjana Ross
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Co-located measurements of acoustic backscatter and temperature/velocity microstructure are used to confirm theoretical predictions of sound scatter from oceanic turbulence. The data were collected with a torpedo-shaped vehicle carrying four shear probes and two thermistors on its nose, and forward-looking 44.7 and 307 kilohertz echosounders (mounted 20 centimetres below the turbulence sensors). The vehicle was towed through the stratified turbulence that forms tidally over the lee side of a sill in a British Columbia fjord. Conventional downward-looking echosounder measurements were also made with a 100 kilohertz sounder mounted in the ship's hull. Populations of amphipods, euphausiids, copepods and gastropods were present in the fjord (sampled with 335-micrometre mesh vertical net-hauls)and could be seen in the sounder data. These plankton net-hauls indicated that there were too few zooplankton in the turbulent regions to account for the scattering intensity. At both 44.7 and 307 kilohertz, scatter that is unambiguously correlated with turbulence was observed. Turbulent scatter is much stronger at the higher frequency, illustrating the mportance of salinity microstructure?long neglected in turbulent scattering models?and shedding some light on the form of the turbulent temperature-salinity co-spectrum. The turbulent temperature-salinity co-spectrum has never been measured directly. Although several models have been proposed for the form of the co-spectrum, they all produce unsatisfactory results when applied to the turbulent scattering equations (either predicting negative scattering cross-sections in some density regimes or predicting implausible levelsof correlation between temperature and salinity at some scales). A new co-spectrum model is proposed and shown to be not only physically plausible in all density regimes, but also in reasonable agreement with the scattering data. At 307 kilohertz, the backscatter is mostly from salinity microstructure and, depending on the strength of the stratification, can be as strong as?or stronger than?the signal froma zooplankton scattering layer. This could easily confound zooplankton biomass estimatesin turbulent regions. The two targets' different natures (discrete targets versus a volume effect) often allow them to be distinguished even when they occur simultaneously. The key is sampling the same targets at multiple ranges. At long-range, discrete targets have a constant volume scattering strength proportional to their number density. The sampling volume, however, decreases as the targets approach the sounder. At some range there will be only one (or no) target in the sampling volume and the volume scattering strengthwill increase (or disappear) as the target continues to near the sounder. Turbulence, as a volume scattering effect, has no range dependence to its volume scattering strength. Thus, by examining the scattering nature at close range we can distinguish discrete targets (like zooplankton) from turbulence.
Author: Neil R. Andersen
Publisher: Plenum Publishing Corporation
ISBN:
Category : Science
Languages : en
Pages : 880
Get Book Here
Book Description
Author: Robert J. Urick
Publisher:
ISBN:
Category : Sound
Languages : en
Pages : 268
Get Book Here
Book Description
Author: Michael Dennis Mintz
Publisher:
ISBN:
Category :
Languages : en
Pages : 90
Get Book Here
Book Description
Author: L. Brekhovskikh
Publisher: Springer Science & Business Media
ISBN: 3662023423
Category : Science
Languages : en
Pages : 262
Get Book Here
Book Description
The continents of our planet have already been exploited to a great extent. Therefore man is turning his sight to the vast spaciousness of the ocean whose resources - mineral, biological, energetic, and others - are just beginning to be used. The ocean is being intensively studied. Our notions about the dynam ics of ocean waters and their role in forming the Earth's climate as well as about the structure of the ocean bottom have substantially changed during the last two decades. An outstanding part in this accelerated exploration of the ocean is played by ocean acoustics. Only sound waves can propagate in water over large distances. Practically all kinds of telemetry, communication, location, and re mote sensing of water masses and the ocean bottom use sound waves. Propa gating over thousands of kilometers in the ocean, they bring information on earthquakes, eruptions of volcanoes, and distant storms. Projects using acoustical tomography systems for exploration of the ocean are presently be ing developed. Each of these systems will allow us to determine the three-di mensional structure of water masses in regions as large as millions of square kilometers.
Author: United States. Naval Oceanographic Office
Publisher:
ISBN:
Category : Echo scattering layers
Languages : en
Pages : 652
Get Book Here
Book Description
Author: Takashi Ichiye
Publisher:
ISBN:
Category : Ocean
Languages : en
Pages : 418
Get Book Here
Book Description
Author: Akira Ishimaru
Publisher: John Wiley & Sons
ISBN: 9780780347175
Category : Education
Languages : en
Pages : 608
Get Book Here
Book Description
Electrical Engineering Wave Propagation and Scattering in Random Media A volume in the IEEE/OUP Series on Electromagnetic Wave Theory Donald G. Dudley, Series Editor This IEEE Classic Reissue presents a unified introduction to the fundamental theories and applications of wave propagation and scattering in random media. Now for the first time, the two volumes of Wave Propagation and Scattering in Random Media previously published by Academic Press in 1978 are combined into one comprehensive volume. This book presents a clear picture of how waves interact with the atmosphere, terrain, ocean, turbulence, aerosols, rain, snow, biological tissues, composite material, and other media. The theories presented will enable you to solve a variety of problems relating to clutter, interference, imaging, object detection, and communication theory for various media. This book is expressly designed for engineers and scientists who have an interest in optical, microwave, or acoustic wave propagation and scattering. Topics covered include: Wave characteristics in aerosols and hydrometeors Optical and acoustic scattering in sea water Scattering from biological materials Pulse scattering and beam wave propagation in such media Optical diffusion in tissues and blood Transport and radiative transfer theory Kubelka—Munk flux theory and plane-parallel problem Multiple scattering theory Wave fluctuations in turbulence Strong fluctuation theory Rough surface scattering Remote sensing and inversion techniques Imaging through various media About the IEEE/OUP Series on Electromagnetic Wave Theory Formerly the IEEE Press Series on Electromagnetic Waves, this joint series between IEEE Press and Oxford University Press offers outstanding coverage of the field with new titles as well as reprintings and revisions of recognized classics that maintain long-term archival significance in electromagnetic waves and applications. Designed specifically for graduate students, practicing engineers, and researchers, this series provides affordable volumes that explore electromagnetic waves and applications beyond the undergraduate level. See page il of the front matter for a listing of books in this series.
Author: D. V. Holliday
Publisher:
ISBN:
Category :
Languages : en
Pages : 45
Get Book Here
Book Description
The long term objectives of this research are to provide a tool for observing oceanic events on a length scale smaller than those associated with internal waves and to provide improved predictive capabilities for direct path propagation fluctuations in the 20 to 70 KHz regime, where small scale events can dominate forward acoustic scattering. Scattering of an acoustic signal by the dynamic processes and the heterogeneous chemical and physical distribution of properties that exist in the open ocean have received considerable attention in the last decade. Our understanding of the effects of stochastic volume scatter mechanisms on a propagating acoustic field, both at the level of the second-order statistics (signal coherence measures, spread functions) and at the level of fourth-order statistics (signal intensity fluctuations and correlations) is reasonably complete. A comparably detailed description of the structure and mechanisms of physical oceanography at intermediate-to-fine scales is not yet well developed. This report represents a part of an effort to develop theory on which to base the development of new techniques to be used in developing a better understanding of the intermediate and fine scale physical processes. These are the processes that exist between the spatial scales of internal waves and the dissipative range of turbulent ocean structure.
