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  • Humans  (4,057)
  • Analytical Chemistry and Spectroscopy
  • Biochemistry and Biotechnology
  • Underwater acoustics
  • American Association for the Advancement of Science (AAAS)  (4,056)
  • Woods Hole Oceanographic Institution  (27)
  • 2015-2019  (910)
  • 2005-2009  (3,173)
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  • 1
    Publication Date: 2022-05-25
    Description: This report describes the design and capabilities of a new ocean bottom hydrophone instrument. The instrument is microprocessor controlled and records digitally on a commercially available cartridge tape recorder with a formatted capacity of 16.7 megabytes. It can operate at sampling intervals between 80 and 8500 Hz and has a dynamic range of 120dB. Both the hardware and software are designed to provide the maximum flexibility in operation allowing either preprogrammed or event detect operation for either short deployment high sampling rate experiments or extended deployment low data rate applications. The microprocessor and recording electronics are capable of handling four data channels and thus the existing recording package is suitable for the ocean bottom seismometer application (or similar} with little or no modification.
    Description: Prepared for the Office of Naval Research under Contract N00014-82-C-0019; NR 083-004.
    Keywords: Hydrophone ; Underwater acoustics
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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  • 2
    Publication Date: 2022-05-25
    Description: The results of an unclassified Workshop on Shallow Water Acoustics, sponsored by the Office of Naval Research Code 11250A, are presented. The workshop was held on April 24-26, 1991 at the Woods Hole Oceanographic Institution and included about forty-five scientists specializing in ocean acoustics, geology, geophysics, and physical oceanography. The goal of the workshop was to determine future directions for basic research in shallow water acoustics. This report summarizes the recommendations of the workshop and includes a synopsis of the deliberations of four working groups which focus on the following specific research issues: (1) the seabed, (2) the water column and surface/Arctic, (3) analytic and numerical modeling/ambient noise, and (4) laboratory and field experiments/signal processing.
    Description: Funding was provided by the Office of Naval Research through Contract No. NOOOl4-91-J-1776.
    Keywords: Shallow water acoustics ; Underwater acoustics ; Basic research recommendations
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
    Format: 1581289 bytes
    Format: application/pdf
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  • 3
    Publication Date: 2022-05-25
    Description: The primary objective of this publication is to share with a wider audience the valuable information and extensive dialogue that took place amongst over 140 individuals who attended the second in a series of planned workshops on the science and management of coastal landforms in Massachusetts. This workshop took place at the Woods Hole Oceanographic Institution on January 24, 2001. The individuals who attended this workshop are actively engaged in planning, managing, regulating, engineering, educating, and studying coastal landforms and their beneficial functions. This workshop titled, Can Humans & Coastal Landforms Co-exist?’, was a natural follow-up to a previous workshop, Coastal Landform Management in Massachusetts, held at WHOI October 9-10, 1997 (proceedings published as WHOI Technical Report #WHOI-98-16). The workshop had a very practical, applied focus, providing state-of-the-art scientific understanding of coastal landform function, case history management and regulation of human activities proposed on coastal landforms, a multi-faceted mock conservation commission hearing presented by practicing technical consultants and attorneys that involved all attendees acting as regulators in breakout sessions, and, at the conclusion of the workshop, an open discussion on all issues related to the science and management of coastal landforms, including future research needs.
    Description: Funding for these proceedings was provided by WHOI Sea Grant and the NOAA National Sea Grant College Program Office, Department of Commerce, under NOAA Grant No. M10-2, Woods Hole Oceanographic Institution Sea Grant Project No. NA86R60075.
    Keywords: Coastal ; Landforms ; Humans
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
    Format: 1574993 bytes
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  • 4
    Publication Date: 2022-05-25
    Description: This report describes the development of a facility for recording time-varying computer graphics on video tape. The primary purpose of the facility is to produce animation sequences of ocean and seafloor acoustic wave fields from output of the synthetic seismogram numerical model FINDIF, and to record them on convenient portable VHS video tapes. The facility utilizes a suite of computer programs called AFRAME, and an Abekas model A60 digital video disk which is connected to the modeling computer and to broadcast quality video recording equipment.
    Description: This work was carried out under ONR Grant #N00014-90-J-1493
    Keywords: Seismograms ; Acoustic models ; Underwater acoustics
    Repository Name: Woods Hole Open Access Server
    Type: Working Paper
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  • 5
    Publication Date: 2022-05-25
    Description: A study was carried out to quantify the level of numerical noise in numerical scattering chamber (NSC) calculations and to compare these noise levels with signal levels of body waves, interface waves and ambient noise. The amplitudes of signal and noise in snapshots from the numerical scattering chamber were quantified at 50 and 65 periods for a few reference models. Models with homogeneous subseafloor structure were studied to determine the level of numerical noise; models with a wavenumber-correlation length product of one were examined to determine signal levels. Models were run with both Higdon and telegraph equation absorbing boundaries since the numerical noise within the grid depends on the boundary formulation. Amplitudes were measured along data traces obtained at a grid depth of 3.33 λw and at the seafloor. Forward traveling head waves had typical amplitudes of ±125 but may reached ±250 near the direct wave. Diffraction amplitudes were observed up to ±300. Stoneley wave amplitudes ranged from ±800 up to ±20,000. Numerical noise levels were less than ±25 in most areas of the water and less than ±350 along most of the seafloor. Regardless of the absorbing boundary type, however, there was a region of noise extending up to 15 λw behind the first seafloor reflection at 3.33 λw in which noise levels range from ±100 up to ±600. In this region it is difficult to resolve signal from systematic numerical noise.
    Description: This work was carried out under ONR Grant #N00014-90-J-1493
    Keywords: Underwater acoustics ; Scattering
    Repository Name: Woods Hole Open Access Server
    Type: Working Paper
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  • 6
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    Woods Hole Oceanographic Institution
    Publication Date: 2022-05-26
    Description: This report describes a non-rigid, floating, four-hydrophone array that can give accurate three-dimensional locations for certain underwater sound sources, particularly for those that are close. For more distant sounds, the array can indicate good directions (bearings) but range is liable to be uncertain. A system for concurrent calibration permits periodic reassessment of hydrophone positions. Appendix: Programming and mathematics for computer analysis of the array data are by Donna Ekstrand and Mary Hunt.
    Description: Supported by the Office of Naval Research under Contract N00014-66-C0241; NR 083-004.
    Keywords: Underwater acoustics ; Hydrophone ; Three-dimensional locations ; Array ; Ambient noise ; Instruments
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
    Format: 3659902 bytes
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  • 7
    Publication Date: 2022-05-26
    Description: This report describes a system for underwater acoustic navigation developed, and in use, at the Woods Hole Oceanographic Institution. It includes a brief discussion of the electronic components, operation, mathematical analysis, and available computer programs. There is a series of supplementary Technical Memoranda containing more information on various aspects of the system. We believe that this kind of documentation is more flexible and better meets the needs of potential users than including all technical details in one large volume. These are not final or definitive reports; acoustic navigation capabilities will continue to evolve at W.H.O.I. for some time. Acoustic navigation provides a method of tracking a ship, and an underwater vehicle or instrument package (‘fish’), in the deep ocean. Acoustic devices attached to the ship and fish measure the length of time it takes a sound pulse to travel to acoustic transponders moored on the ocean floor. If the transponder positions and the average speed of sound are known, the ship or fish position can be found.
    Description: Prepared for the Office of Naval Research under Contracts N00014-71-C0284; NR 293-008 N00014-70-C0205; NR 263-103 and the National Science Foundation/International Decade of Ocean Exploration Grant GX-36024 and the Applied Physics Laboratory of The Johns Hopkins University Contract 372111.
    Keywords: Alvin (Submarine) ; Underwater navigation ; Underwater acoustics
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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  • 8
    Publication Date: 2022-05-26
    Description: The Ocean Bottom Seismometer Augmentation in the North Pacific Experiment (OBSANP, June-July, 2013, R/V Melville) addresses the coherence and depth dependence of deep-water ambient noise and signals. During the 2004 NPAL Experiment in the North Pacific Ocean, in addition to predicted ocean acoustic arrivals and deep shadow zone arrivals, we observed "deep seafloor arrivals" (DSFA) that were dominant on the seafloor Ocean Bottom Seismometer (OBS) (at about 5000m depth) but were absent or very weak on the Distributed Vertical Line Array (DVLA) (above 4250m depth). At least a subset of these arrivals correspond to bottomdiffracted surface-reflected (BDSR) paths from an out-of-plane seamount. BDSR arrivals are present throughout the water column, but at depths above the conjugate depth are obscured by ambient noise and PE predicted arrivals. On the 2004 NPAL/LOAPEX experiment BDSR paths yielded the largest amplitude seafloor arrivals for ranges from 500 to 3200km. The OBSANP experiment tests the hypothesis that BDSR paths contribute to the arrival structure on the deep seafloor even at short ranges (from near zero to 4-1/2CZ). The OBSANP cruise had three major research goals: a) identification and analysis of DSFA and BDSR arrivals occurring at short (1/2CZ) ranges in the 50 to 400Hz band, b) analysis of deep sea ambient noise in the band 0.03 to 80Hz, and c) analysis of the frequency dependence of BR and SRBR paths. On OBSANP we deployed a 32 element VLA from 12 to 1000m above the seafloor, eight short-period OBSs and four long-period OBSs and carried out a 15day transmission program using a J15-3 acoustic source.
    Description: Funding was provided by the Office of Naval Research under contract #'s N00014-10-1-0987 and N00014-10-1-0510
    Keywords: Melville (Ship) Cruise MV1308 ; Underwater acoustics ; Oceanographic instruments
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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  • 9
    Publication Date: 2022-05-26
    Description: A sequence of nine nighttime, broadband volume scattering strength measurements obtained in 1973 over a period of approximately one hour was used to study the short-term variability of scattering strength in 100 Hz bands over frequencies ranging from 100 Hz to 24 kHz and depths ranging from 400 meters to 1000 meters. The variability was found to be independent of depth and was least in the frequency range three kHz to eight kHz where the standard deviation was approximately four dB less than the mean level, Outside this frequency range the standard deviation was somewhat greater than the mean level.
    Description: This work was funded by the Naval Underwater Systems Center, Commercial Acquisition Dept., Building 11, Code 09, Newport, Rhode Island 02841-5047 under contract number N00140-85-C-JA45.
    Keywords: Underwater acoustics ; Sound-waves
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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  • 10
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    Woods Hole Oceanographic Institution
    Publication Date: 2022-05-26
    Description: This is the final report of Contract N00014-84-C-0185 between the Woods Hole Oceanographic Institution and the Office of Naval Research for the contract period 1 January, 1984, to 28 February, 1985. This contract supported an experiment that was conducted in the Norwegian Sea during May and June of 1984 to assess the possibilities of using ocean acoustic tomography as a measuring tool in the Arctic. The object of the experiment was to identify and determine the temporal stability (coherence), and resolvability, of Arctic acoustic paths. Identification refers to the ability to match a pulse arrival with a particular ray path, primarily through computer modelling. Resolvable rays are those that arrive sufficiently far apart in time so as to be distinct and separable. In order to use tomography, rays must be identified, resolved and stable. Unlike the deep temperate ocean, where there are many wholly refracted paths, the upward refracting Arctic sound speed profile causes ray paths to reflect off the ice-covered surface of the permanent pack and the mixed ice-covered and ice-free surface of the marginal ice zones. The reflection process is time-varying and hence leads to resolvability, identification and stability questions that do not arise in the case of entirely refracted paths. A 224 Hz acoustic source was moored in an ice-free region. It transmitted phase coded, frequency stable signals to receivers fixed on the bottom and receivers drifting with the icepack at ranges of approximately 150 km. The received signals are to be analyzed with respect to identification, resolvability and stability issues. This contract covered the costs associated with installation and retrieval of the source and preliminary data reduction from the drifting and fixed hydrophones. Detailed data analysis costs are to be covered elsewhere. Nevertheless, preliminary analysis indicates that the received signals, particularly those from paths that interact with the ice-free surface, appear to have sufficient stability for tomographic purposes.
    Description: Funding was provided by the Office of Naval Research under Contract N00014-84-C-0185.
    Keywords: Underwater acoustics ; Tomography ; Sound ; Hearing
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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