Download or read book Remote Sensing of Submerged Objects and Geomorphology in Continental Shelf Waters with Acoustic Waveguide Scattering written by Purnima Ratilal and published by . This book was released on 2002 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: (Cont.) A generalized extinction theorem for object scattering in a stratified medium is derived that can be applied to detect and classify objects from the total field in the forward scatter direction in a waveguide. Analytic expressions are derived for the attenuation and dispersion in the forward propagated field due to scattering from random surface and volume inhomogeneities in a waveguide. The unified model is applied to show that the active sonar equation is not in general valid for scattering in a waveguide. It is shown that the sonar equation may be made approximately valid in a waveguide by lowering the active frequency of operation sufficiently for the given measurement scenario to simplify analysis for target classification and localization.

Download or read book The Journal of the Acoustical Society of America written by Acoustical Society of America and published by . This book was released on 2006 with total page 1360 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Oceanic Internal Waves from Ship Aircraft and Spacecraft written by Atlantic Oceanographic and Meteorological Laboratories. Ocean Remote Sensing Laboratory and published by . This book was released on 1978 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Ocean Remote Sensing Laboratory (ORSL) has been studying internal waves using remote sensing techniques employing three different types of observational platforms: ships, aircraft, and spacecraft. Internal waves and their manifestations have been observed using the following techniques: Satellite multispectral scanning imagers (principally in the visible and near-infrared); Radar--both coherent imaging radar and standard meteorological radar (all from aircraft); Hand-held visible photography (from spacecraft, aircraft, and ship; Ship-towed thermistors; and STD and XBT casts.

Download or read book Oceanic Internal Waves from Ship Aircraft and Spacecraft written by Atlantic Oceanographic and Meteorological Laboratory. Ocean Remote Sensing Laboratory and published by . This book was released on 1978 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Acoustic Clutter and Ocean Acoustic Waveguide Remote Sensing OAWRS in Continental Shelf Environments written by and published by . This book was released on 2009 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Acoustic clutter is the primary problem encountered by active sonar systems operating in Continental Shelf environments. Clutter is defined as any return from the environment that stands prominently above the diffuse and temporally decaying reverberation background and so can be confused with or camouflage returns from an intended target such as an underwater vehicle. Many environmental factors may contribute to acoustic clutter and adversely affect the performance of tactical Navy sonar by introducing false alarms in the system. In order to develop adaptive algorithms or technology to mitigate acoustic clutter, it is critical to identify, understand, and be able to accurately model the leading order physical mechanisms which cause clutter in existing sonar systems. The long-term goal of this program is to determine and understand the physical mechanisms that cause acoustic clutter in continental shelf environments and to use this knowledge to develop predictive tools to enhance the detection, localization and classification of underwater targets.

Download or read book Remote Sensing of Shelf Sea Hydrodynamics written by J.C.J. Nihoul and published by Elsevier. This book was released on 2000-04-01 with total page 367 pages. Available in PDF, EPUB and Kindle. Book excerpt: Remote Sensing of Shelf Sea Hydrodynamics

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2003 with total page 812 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Remote Sensing of Coastal Aquatic Environments written by Richard L. Miller and published by Springer Science & Business Media. This book was released on 2007-03-06 with total page 357 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides extensive insight on remote sensing of coastal waters from aircraft and space-based platforms. The primary focus of the book is optical remote sensing using passive instruments, to measure and analyze the coastal aquatic environment. The authors have gathered information from a variety of sources, to help non-specialists grasp new techniques and technology, to quickly produce useful data

Download or read book Surface Waves and Fluxes written by G.L. Geernaert and published by Springer. This book was released on 2011-09-20 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the Conference on Air-Sea Interaction in January 1986, it was suggested to me by David Larner of Reidel Press that it may be timely for an updated compendium of air-sea interaction theory to be organized, developed, and published. Many new results were emerging at the time, i.e., results from the MARSEN, MAS EX, MILDEX, and TOWARD field projects (among others) were in the process of being reported and/or published. Further, a series of new experiments such as FASINEX and HEXOS were soon to be conducted in which new strides in our knowledge of air-sea fluxes would be made. During the year following the discussions with David Larner, it became apparent that many of the advances in air-sea interaction theory during the 1970s and 1980s were associated with sponsor investments in satellite oceanography and, in particular, remote sensing research. Since ocean surface remote sensing, e.g., scatterometry and SAR, requires intimate knowledge of ocean surface dynamics, advances in remote sensing capabilities required coordinated research in air-sea fluxes, wave state, scattering theory, sensor design, and data exploitation using environmental models. Based on this interplay of disciplines, it was decided that this book be devoted to air sea interaction and remote sensing as multi-disciplinary activities.

Download or read book Oceanic Remote Sensing written by F. V. Bunkin and published by . This book was released on 1987 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Enabling High Resolution Population Density Imaging of Random Scatterer Groups in a Fluctuating Range dependent Ocean Waveguide with the Matched Filter Variance written by Mark Andrews and published by . This book was released on 2010 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : Underwater acoustic imaging and surveillance systems often transmit broadband pulses and process the scattered returns with a correlation matched filter in order to achieve high spatial resolution in range localization. When imaging distributed groups of scatterers, such as schools or shoals of fish, bubble clouds and swarms of AUVs, large numbers of individuals, ranging from tens to hundreds of thousands, are often present within each resolution cell of the imaging system. To estimate population density, spatial distribution, scattering cross-section and other parameters of the scatterer group and their error bounds, it is essential to understand the statistical nature and composition of the broadband matched filtered scattered returns. Here, using a combination of theoretical model development and experimental data analysis, we investigate (1) the statistics of broadband acoustic propagation in temporally and spatially varying shallow water waveguides, (2) the statistics and mechanisms for scattering from distributed groups, and (3) the effects of multiple scattering and waveguide dispersion in predicting the level and duration of the broadband matched filtered scattered intensities. The analysis is applied to two types of underwater acoustic imaging systems for mapping fish distributions. (a) The ocean acoustic waveguide remote sensing (OAWRS) system that allows instantaneous wide area continental-shelf scale imaging by utilizing muti-modal waveguide propagation, and (b) the conventional ultrasonic echosounder using direct-path propagation to image scatterer groups over water depth.Using experimental data acquired in the US east coast continental shelf, the scintillation statistics of one-way propagated broadband waveforms are quantified as a function of signal bandwidth, center frequency, and range. The received broadband intensity is shown to follow the Gamma distribution implying the central limit theorem has led to a fully saturated Gaussian field. An efficient numerical approach is developed to estimate the broadband transmission loss in a fluctuating, range-dependent ocean waveguide using spatial averaging of a time-harmonic stochastic propagation model. This approach is essential for rapidly detrending OAWRS imagery to make real time population density estimates.Theoretical models are then developed to determine the statistical moments of the broadband matched filtered scattered returns from distributed groups. For the ultrasonic echosounder, a numerical Monte-Carlo model that includes multiple scattering is developed and implemented to determine the conditions for when multiple scattering is significant. The model is implemented for Atlantic herring schools found in the Gulf of Maine, imaged with a conventional fisheries echosounder. Our analysis indicates that the single-scatter approximation is valid even for dense Atlantic herring schools at ultrasound frequencies. For direct-path imaging systems, an analytic model is also developed to efficiently estimate the scattered field statistics from the group by applying a single scatter approximation. The model can be used to compare the levels of the coherently and incoherently scattered intensities. It provides an explanation for how high spatial resolution is acheived with incoherently scattered fields with the coherent matched filter.We examine the effects of multiple scattering, attenuation, and waveguide dispersion on population density imaging with the OAWRS imaging system by implementing a numerical Monte-Carlo model. The model determines the statistical moments of the matched filtered multiply scattered returns from a distributed group of discrete scatterers, and incorporates propagation through a fluctuating range-dependent ocean environment. Results of the model are applied to interpret OAWRS imagery of shoaling Atlantic herring populations acquired during the NOPP-funded 2006 Experiment in the Gulf of Maine. Our analysis indicates that multiple scattering and attenuation were mostly negligible at OAWRS frequencies employed and for herring densities observed.

Download or read book Breaking Ocean Waves written by Eugene A. Sharkov and published by Springer. This book was released on 2007-07-30 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt: Eugene Sharkov, of the Space Research Institute in Moscow, has here put together the most comprehensive description of the physical findings of an investigation into the spatio-temporal characteristics of the gravity of breaking waves. He’s also described the foam activity in the open sea using methods and instruments of optical and microwave remote sensing. Numerous practical applications and illustrations are provided from air-borne, ship-borne and laboratory up-to-date experiments.

Download or read book Continuous Monitoring of Fish Population and Behavior by Instantaneous Continental Shelf Scale Imaging with Ocean Waveguide Acoustics written by and published by . This book was released on 2007 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: The long-term goals of this program are to (1) instantaneously detect, image and spatially chart fish populations over continental-shelf scales, and (2) continuously monitor the areal densities and behavior of these fish populations over time using a novel audible frequency acoustic system (300- 5000Hz) referred to as Ocean Acoustic Waveguide Remote Sensing (OAWRS). This new method is being applied to explore the abundance, temporal and spatial distributions and behavior of fish populations in the Gulf of Maine on and near Georges Bank, a marine ecosystem being studied in the Census of Marine Life program. OAWRS is a valuable conservation tool for rapid imaging and enumeration of large scale fish populations over thousands of square kilometers to effectively monitor and manage the national fish stock.

Download or read book Optical Properties and Remote Sensing of Inland and Coastal Waters written by Robert P. Bukata and published by . This book was released on 2018 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Marine Optics written by N.G. Jerlov and published by Elsevier. This book was released on 1976-01-01 with total page 247 pages. Available in PDF, EPUB and Kindle. Book excerpt: Marine Optics

Download or read book Physics of Tsunamis written by Boris Levin and published by Springer Science & Business Media. This book was released on 2008-10-27 with total page 333 pages. Available in PDF, EPUB and Kindle. Book excerpt: Till the very end of the twentieth century tsunami waves (or ‘waves in a harbour’, translated from Japanese) were considered an extremely rare and exotic natural p- nomenon, originating in the ocean and unexpectedly falling upon the seaside as gigantic waves. The 26th of December 2004, when tsunami waves wiped out, in a single day, more than 250,000 human lives, mourned in many countries, turned out to be a tragic date for all mankind. The authors of this book, who have studied tsunami waves for many years, - tended it to be a systematic exposition of modern ideas concerning • The mechanisms of tsunami wave generation • The peculiarities of tsunami wave propagation in the open ocean and of how waves run-up beaches • Methods for tsunami wave registration and the operation of a tsunami warning system • The mechanisms of other catastrophic processes in the ocean related to the se- mic activity of our planet The authors considered their main goal to be the creation of book prese- ing modern knowledge of tsunami waves and of other catastrophes in the ocean to scienti?c researchers and specialists in geophysics, oceanography, seismology, hydroacoustics, geology, geomorphology, civil and seaside engineering, postgr- uate students and students of relevant professions.

Download or read book Experimental Acoustic Inversion Methods for Exploration of the Shallow Water Environment written by Andrea Caiti and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, research on acoustic remote sensing of the ocean has evolved considerably, especially in studying complex physical and biological processes in shallow water environments. To review the state of the art, an international workshop was held at Carvoeiro, Portugal, in March 1999, bringing together leading international researchers in the field. In contrast to much of the recent theoretical work, emphasis was placed on the experimental validation of the techniques. This volume, based on presentations at this workshop, summarizes a range of diverse and innovative applications. The invited contributions explore the use of acoustics to measure bottom properties and morphology, as well as to probe buried objects within the sediment. Within the water column, sound is applied to imaging of oceanographic features such as currents and tides or monitoring of marine life. Another key theme is the use of sound to solve geometric inverse problems for precise tracking of undersea vehicles. Audience: This volume should be useful both to the novice seeking an introduction to the field and to advanced researchers interested in the latest developments in acoustic sensing of the ocean environment. The workshop was sponsored by the Fundação para a Ciêcia e a Tecnologia (Portuguese Foundation for Science and Technology).