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IEEE Journal of Oceanic Engineering

Issue 4 • Date Oct 1990

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Displaying Results 1 - 15 of 15
  • Low-frequency ambient-noise measurements in the South Fiji basin

    Publication Year: 1990, Page(s):311 - 315
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (408 KB)

    The effect of wind speed on ambient noise has been measured in an experiment carried out in the South Fiji basin. The noise data in the band 15-250 Hz are well correlated with the variations in the local wind speed. The relationship between noise level N and wind speed ν is expressed by N=B+20n log ν. The constants B and n have been estim... View full abstract»

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  • Acoustically relevant bubble assemblages and their dependence on meteorological parameters

    Publication Year: 1990, Page(s):340 - 349
    Cited by:  Papers (82)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (980 KB)

    A detailed physical model of the life history of a typical bubble plume, from its formation by a breaking wave to its dissipation into the background bubble population, is given, and the relationship between the early, acoustically relevant stages in bubble-plume development and the associated, remotely detectable whitecap is described. The manner in which the fraction of the sea surface covered b... View full abstract»

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  • Measuring the vertical directional spectra caused by sea surface sound

    Publication Year: 1990, Page(s):299 - 310
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1080 KB)

    The results of the initial deployment of a wideband (40-4000 Hz) vertical acoustic antenna system in the Tongue of the Ocean, the Bahamas are discussed. The instrumentation system consisted of seven octavely nested, four-wavelength linear apertures covering the above frequency range, and a VCR-based subsurface recording system that carried out a programmed sequence of recordings. The objective of ... View full abstract»

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  • Vertical directionality of ambient noise at 32°N as a function of longitude and wind speed

    Publication Year: 1990, Page(s):335 - 339
    Cited by:  Papers (10)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (388 KB)

    Measurements of the ambient-noise field between 50 and 300 Hz with vertical arrays at 32°N (124°W, 136°W, and 150°W) have been made. Substantial differences in the vertical distribution of noise have been measured (especially at the higher frequencies), which can be interpreted in the context of attenuation by seawater sound absorption of coastal shipping noise. Under low wind-spee... View full abstract»

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  • Depth dependence of noise resulting from ship traffic and wind

    Publication Year: 1990, Page(s):292 - 298
    Cited by:  Papers (15)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (552 KB)

    Under conditions of distantly generated noise, the noise level is found to decrease with depth in the mid-northeastern Pacific. These data show a decrease in noise level greater than 25 dB between critical depth and the ocean bottom. A result of this decrease is that locally wind-generated noise can be detected on near-bottom receivers for wind speeds less than 10 kn. It is shown that the noise le... View full abstract»

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  • Matched field processing of deep-water ambient noise

    Publication Year: 1990, Page(s):316 - 323
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1052 KB)

    Matched-field ambiguity surfaces produced by deep-water ambient-noise data are discussed and quantified in terms of power levels and correlation values. Two processors were implemented (Bartlett and minimum variance) using data at 35 and 95 Hz with similar but distinct vertical angular distributions. In general, the ambiguity surfaces have both diffuse and discrete components. The diffuse distribu... View full abstract»

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  • Characteristics of SeaMARC II phase data

    Publication Year: 1990, Page(s):350 - 360
    Cited by:  Papers (18)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1040 KB)

    The dispersion of SeaMARC II phase-difference samples is discussed. They appear to be a function of signal direction, range, noise level, and backscatter strength of the bottom. Field data from a lava flow area and from sedimented areas at different depths are compared. The temporal distribution of the phase-difference samples was skewed and asymmetrical about the model. The angular distribution w... View full abstract»

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  • Bubbles as sources of ambient noise

    Publication Year: 1990, Page(s):268 - 274
    Cited by:  Papers (21)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (832 KB)

    It has been shown that the main mechanism which produces the Knudsen region of the ambient noise spectrum is the free oscillations of bubbles. Some experimental results which seem to confirm these facts and to refute various alternative theories involving spray impacts and turbulent forcing of bubble oscillations are described. The results show that the mechanism which excites the bubbles is their... View full abstract»

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  • Deep-ocean vertical noise directionality

    Publication Year: 1990, Page(s):324 - 334
    Cited by:  Papers (17)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (948 KB)

    The structure of beam noise measured at the output of a vertical array in a range dependent ocean basin was investigated using the modified wide-angle parabolic equation (PE). Noise sources were distributed throughout the basin, and the field due to each noise source at an array located in the midbasin was calculated. The response of the array to the superposition of the noise sources was found by... View full abstract»

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  • Low-frequency acoustic wave-scattering phenomena under ice cover

    Publication Year: 1990, Page(s):361 - 372
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (904 KB)

    Studies on low-frequency acoustic wave-scattering phenomena due to under-ice roughness made by utilizing a rough, thin-ice plate model are presented. The model naturally divides the reflected field solution into specular and off-specular components. The model for specular components can give an excellent propagation loss prediction if the combined effects of under-ice roughness scattering, ice abs... View full abstract»

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  • Underwater noise emissions from bubble clouds

    Publication Year: 1990, Page(s):275 - 281
    Cited by:  Papers (40)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (540 KB)

    By means of an effective equation model for the propagation of pressure waves in a bubbly liquid, the normal modes of oscillation of regions of bubbly liquid in an otherwise pure liquid are calculated for some simple geometries. It is shown that the frequencies of oscillation of such bubble clouds can be much lower than those of the constituent bubbles in isolation and fall well within the range w... View full abstract»

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  • An electromagnetic current meter-based system for application in unsteady flows

    Publication Year: 1990, Page(s):373 - 379
    Cited by:  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (680 KB)

    A flexible configuration for an array of sensors has been developed for measurements in energetic regions of the ocean where the flow has high spatial and temporal variability. Central to the system is a two-axis electromagnetic current meter that measures the flow through a ducted volume containing a uniform magnetic field and nonprotruding electrodes flush with the duct surfaces. This geometry m... View full abstract»

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  • Experimental investigation of the wave-interaction mechanism for ambient noise

    Publication Year: 1990, Page(s):282 - 285
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (332 KB)

    An experimental investigation of the wave-interaction mechanism for wind-generated ambient noise is presented. Predictions based on dispersion theory for frequencies above 10 Hz fall below experimental data and do not account for wind-speed dependence. The discrepancy may rest either in the linear wave-model or the mechanism. Laboratory measurements of wind waves show low spatial coherence and no ... View full abstract»

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  • Inverted echo sounder measurement of dynamic height through an ENSO cycle in the central equatorial Pacific

    Publication Year: 1990, Page(s):380 - 383
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (340 KB)

    A four-year record from an inverted echo sounder deployed near Palmyra Island at 6°N in the central Pacific Ocean is compared with a simultaneous record of subsurface pressure from this island lagoon. A factor m, converting round-trip acoustic travel time to surface dynamic height relative to a deep pressure level, was estimated from the ratio of the spectra of the two records in the ... View full abstract»

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  • Ambient noise data logger buoy

    Publication Year: 1990, Page(s):286 - 291
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (500 KB)

    A buoy for measuring wind speed and the ambient noise sound pressure level from 10 to 1500 Hz with 1-Hz resolution is described. The measurement buoy was deployed in a remote fjord in southeastern Alaska from October to December, 1989. The results from the data collected show that, for a wind speed of 5 kn, the measured ambient noise level at 900 Hz lies well below the Knudsen curve for open-ocean... View full abstract»

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Aims & Scope

The IEEE Journal of Oceanic Engineering (ISSN 0364-9059) is the online-only quarterly publication of the IEEE Oceanic Engineering Society (IEEE OES). The scope of the Journal is the field of interest of the IEEE OES, which encompasses all aspects of science, engineering, and technology that address research, development, and operations pertaining to all bodies of water. This includes the creation of new capabilities and technologies from concept design through prototypes, testing, and operational systems to sense, explore, understand, develop, use, and responsibly manage natural resources.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
N. Ross Chapman
School of Earth & Ocean Sciences
University of Victoria
3800 Finnerty Road
Victoria, BC V8P 5C2 Canada
chapman@uvic.ca