2 edition of Acoustic mode coherence in the Arctic Ocean found in the catalog.
Acoustic mode coherence in the Arctic Ocean
John J. Polcari
|Statement||by John J. Polcari.|
|Series||WHOI / Woods Hole Oceanographic Institution -- 86-38., WHOI (Series) -- 86-38.|
|The Physical Object|
|Pagination||297 p. :|
|Number of Pages||297|
ALUMNI. Doctoral Degrees in DSPG. Ronald W. Schafer, Nonlinear Filtering of Convolved Signals (PhD ) Joseph Siegel, Analytical Equiripple Nonrecursive Approximations to Ideal Low-Pass Digital Filters (PhD ) Russell M. Mersereau, Digital Reconstruction of Multidimensional Signals from their Projections (ScD ) Ronald Crochiere, Digital Network Theory and its Applications to the. We use the spatial coherence matrix of a wave field as a matrix whose support is a connectivity matrix of a graph with sensors as vertices. The support of the covariance matrix is estimated from limited-time data using a hypothesis test with a robust phase-only coherence test-statistic. Inversion of ocean acoustic sound speed profiles (SSPs. North Pacific Acoustic Laboratory. The objectives of the NPAL program are to understand the basic physics of low-frequency, long-range, broadband propagation, the effects of environmental variability on signal stability and coherence, and the fundamental limits to signal processing at long-range imposed by ocean processes. 31 Dec A tail contact could only mean one thing: there was a submarine in the area. Splash lifted the nose and climbed to an altitude to gain radar coverage. His radar picture was covered in hundreds of contacts – floating debris from crashed NGO ocean drones, surfaced whales, and even the white caps from the rough seas populated his screen.
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Acoustic Mode Coherence in The Arctic Ocean. May ; when applied to the vertical array deployed during the FRAM IV Arctic acoustic experiment is analyzed. HILL BOOK. The high levels of coherence observed (O to ) show that tonal signal propagation in the Arctic channel is essentially deterministic for time periods well in excess of one hour.
The various modes may then be considered to maintain a constant phase relationship over time. Such systems provide acoustic remote sensing of temperatures via ocean acoustic tomography, underwater navigation, and passive acoustic monitoring of natural and anthropogenic sounds.
Such systems have a special role in making measurements of the rapidly changing Arctic Ocean and complementing and supporting other in situ observations. 18 P. Acoustic Thermometry in the Arctic Ocean Mode 1 speeds up Gavrilov and Mikhalevsky, 0 6 7 8 9 Time, day Time, s 10/10/ 12/8/ + °C OVER KM OF THE PATH DIFFERENCE IN ARRIVAL TIME OF MODE 1 and MODE Acoustic thermometry for Arctic Ocean climate Abstract: Several climate models suggest that the Arctic Ocean may be one of the more sensitive indicators of global climate change.
In addition to changes in the Arctic Ocean temperature, the ice pack will also respond to these changes; for example, its mean thickness, roughness and the percentage of open water will all be modulated.
Ocean Acoustic Propagation: Fluctuations and Coherence in. Dynamically Active Shallow-Water Regions. coherence length is diminished by the presence of internal waves between the source and receiver.
acoustic mode beams can emerge from the duct, with the beams of each mode. Ocean Acoustic Tomography “ Statistics of normal mode amplitudes in an ocean with random sound-speed perturbations: Cross-mode coherence and mean intensity,” J.
Acoust. Soc. (3), “ Multipurpose acoustic networks in the integrated Arctic Ocean observing system,” Arctic Packets of intense internal waves are modeled as coherent structures moving along the acoustic propagation path without changing shape.
The packets cause mode coupling and their motion results in a changing acoustic interference pattern. The model is consistent with the rapid decorrelation observed in SWARM. The model also predicts the observed partial recorrelation of the. The ocean models and the acoustic simulation tools will be run by the PI and by Arthur Newhall, in collaboration with other members of the WHOI Ocean Acoustics and Signals Laboratory.
Five acoustic studies are planned: 1. Canyon and slope acoustics: Identify purely geometrically controlled (no ocean.
Arctic Acoustics: The primary goal here is to understand the effects of changing Arctic conditions on acoustic propagation and ambient noise, particularly in under-ice environments. The thinning ice in the Arctic may result in reduced transmission loss compared to that observed during earlier investigations.
Freitag et al. achieved acoustic communication and navigation under Arctic ice for 10– km, and an acoustic communication experiment in 5–m-deep water under shore-fast ice near Prudhoe Bay in Alaska showed that (i) the achievable data rates depended on the range and water depth and (ii) long-baseline navigation under ice was feasible.
However, cross-ice acoustic (CIA) propagation. The Ocean Acoustics library contains acoustic modeling software and data. It is supported by the U.S. Office of Naval Research (Ocean Acoustics Program) as a means of publishing software of general use to the international ocean acoustics community.
Double‐diffusive convection manifests as distinct layered structures (staircases), which are prominent throughout the Arctic Ocean. Here, we use a time series of acoustic measurements with high temporal and spatial resolution to track a double‐diffusive staircase. The high‐resolution acoustic data allow for an investigation of real‐time changes in double‐diffusive features, which are then related to.
The. Abstract— A long-range acoustic navigation system with built- in acoustic communications capability has been developed for use by underwater gliders, drifters and vehicles under Arctic ice where surfacing to acquire GPS position may be risky or impossible.
The system consists of multiple buoys placed on the ice with transducers suspended m below, each of which is programmed to. Linear and Nonlinear Ocean Acoustic Propagation Models. Pages Low Frequency Attenuation in the Arctic Ocean. Pages DiNapoli, Frederick R. (et al.) Preview Buy Chap95 € Effect of Sub-Bottom Inhomogenieties on Shallow Water Spatial Coherence.
Pages Instead, methods based on only the wander of the mode arrivals are used to estimate path-averaged temperatures and internal tide "strength".
The modal phase structure function is introduced as a useful proxy for acoustic coherence, and is related via an integral transform to the environmental sound speed correlation function.
Results of numerical simulation of the total and coherent sound fields and the coherence parameter for a multimode acoustic signal excited by a monochromatic sound source and propagating in an irregular arctic waveguide are presented.
Expressions used as the basis for the algorithm of the sound field calculation by the method of coupled normal modes are given. High-resolution bathymetry of extinct asphalt volcanoes off the coast of California. The bathymetry was collected using the autonomous underwater vehicle Sentry.
(Image by Dana Yoerger, Woods Hole Oceanographic Institution) Acoustics is the science of sound; ocean acoustics attempts to describe how sound behaves in the ocean. A strong understanding of how. The presence of the year-round sea ice cover determines the unique character of acoustic propagation and ambient noise in the Arctic Ocean.
The sea ice nsulates the Arctic Ocean from solar heating in the summer months, creating a year-round upward refracting sound speed profile with the sound speed minimum at the water–ice interface. The Canada Basin Acoustic Propagation Experiment (CANAPE) was a year-long experiment exploring the changing nature of sound propagation and ambient noise in the Arctic ocean.
Among the literature on acoustics the book of Pierce  is an excellent introduction available for a low price from the Acoustical Society of America. In the preparation of the lecture notes we consulted various books which cover different aspects of the problem [15, 17, 19, 39, 50, 72, 89, 95,, ].
Ocean Acoustic Propagation and Coherence Studies. Timothy F. Duda. Applied Ocean Physics and Engineering Department, MS Woods Hole Oceanographic Institution, Woods Hole, MA phone: () fax: () email: [email protected] Award Number: N Estimation of Ice Surface Scattering and Acoustic Attenuation in Arctic Sediments from Long-Range Propagation Data.- Low Frequency Attenuation in the Arctic Ocean.- Effect of Sub-Bottom Inhomogenieties on Shallow Water Spatial Coherence.- Mode Coupling from Subbottom Roughness.- Sediments: Seismo-Acoustic Waves and Geoacoustic Characteristics Impact of a Changing Arctic on Acoustic Networks The Arctic Ocean continues its unprecedented transition towards an ice-free state.
The smallest sea ice extent ever recorded in the Arctic Ocean was observed ineclipsing the previous record set in This paper presents a review of the underwater acoustics of the Arctic Ocean. It discusses the main features of the underwater acoustic environment and how they are so strongly affected by the presence of ice cover.
The paper also discusses the history of Arctic Ocean acoustics research, how the motivation was originally military in character during the Cold War and how it changed to being.
Part of the NATO Conference Series book series (NATOCS, volume 5) Log in to check access. Buy eBook Coherence and Signal Processing. Fluctuation Statistics of Sea-Bed Acoustic Backscatter of Geophysical Methods 'and Equipment to Explore the Sea Bottom.
•• •••. • 53 H. Weichart The Acoustic Response of Some Gas-Charged. Meanwhile, let me say this, in the spirit of opinion-based communications – the diffusors made by Acoustic Geometry are better because they’re based on coherent diffusion, or more accurately, phase coherency.
The mean and variance of the acoustic field forward propagated through a stratified ocean waveguide containing three-dimensional (3-D) random internal waves is modeled using an analytic normal mode formulation.
The formulation accounts for the accumulated effects of multiple forward scattering. These lead to redistribution of both coherent and incoherent modal energies, including attenuation. 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.
Email: [email protected] Mailing Address: IGPP Scripps Institution of Oceanography UC San Diego Gilman Dr # La Jolla, CA Location:. active acoustic surveillance in the new Arctic.
Autonomous, Integrated Sensing Modeling and Control for adapting the AUV survey to the dramatically changing acoustic environment in the Arctic Environmentally Adaptive Communication and Navigation in the Arctic (ONR) The MIT operation of a BF21 with a towed array in ICEX16 demonstrated the severe.
The mean and variance of the acoustic ﬁeld forward propagated through a stratiﬁed ocean waveguide containing three-dimensional 3-D random internal waves is modeled using an analytic normal mode formulation. The formulation accounts for the accumulated effects of multiple forward scattering.
These lead to redistribution of both coherent and. Watanabe, Y, Meguro, K, Deguchi, M, Kida, Y, & Shimura, T. "Integrated Acoustic Communication and Positioning System Between an Autonomous Surface Vehicle and Autonomous Underwater Vehicles." Proceedings of the ASME 38th International Conference on Ocean, Offshore and Arctic Engineering.
Volume 6: Ocean Space Utilization. Glasgow, Scotland. The Arctic Ocean affects the way of life of not only the Arctic native peoples, but also those of us living “downstream,” in Europe and North America.
As such, the Arctic Ocean, and the effect of changes that are taking place there, are the focus of intense study by oceanographers of all disciplines. 1 Introduction. Much of the interior of the Arctic Ocean is quiescent (Fer, ; Lincoln et al., ), insulating the surface from heat imported into the Arctic Ocean by Atlantic Water intruding at intermediate depths (Carmack et al., ).In the Arctic basins, diapycnal heat fluxes out of this main oceanic heat source are weak.
Multipurpose Acoustic Networks in the Integrated Arctic Ocean Observing System Surface gravity waves and their acoustic signatures, Hz, on the mid-Pacific sea floor The sound of climate change. Tidal analysis of T/P data from to is used to predict in situ time series measured during the Hawaiian Ocean mixing experiment (HOME), the reciprocal tomography experiment (RTE87), and the acoustic mid-ocean dynamics experiment (AMODE), demonstrating both the temporal coherence and the lack of incoherent elements.
Acoustic energy in the ocean is significantly scattered by sound speed fluctuations induced by internal waves. and Van-Kampen (). The review on the subject can be found in books of Rytov et al.
(), Ishumaru (). Scattering of Sound in Shallow-Water Waveguides Theoretical expressions for cross-mode coherence versus range from. The Arctic Ocean. It is a comment on the unimportance of the North Pole as an incentive to exploration that hardly any of the real exploration of the Arctic Ocean can be credited to the pole seekers.
The great exception is Nansen, whose work in the Fram stood alone until the s; but, although Nansen made a bid to reach the pole, his primary aim was rather to study the waters and bottom. Email: [email protected] Mailing Address: IGPP Scripps Institution of Oceanography UC San Diego Gilman Dr # La Jolla, CA Location: IGPP II/ Phone: ().
Second moments of mode amplitudes at fixed frequency as a function of separations in mode number, time, and horizontal distance are investigated using mode-based transport equations and Monte Carlo simulation.
These second moments are used to study full-field acoustic coherence.Inverse acoustic sensing. Stochastic modeling, broadband modeling, matched field processing, acoustic tomography, coupled ocean-acoustic modeling, 3D modeling, nonlinear acoustics, and chaotic metrics.
Rapid environmental assessments. Underwater acoustic networks and vehicles, channel models, and localization methods.Statistics of normal mode amplitudes in an ocean with random sound-speed perturbations: Cross-mode coherence and mean intensity JA Colosi, AK Morozov The Journal of the Acoustical Society of America (3),