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  • Underwater acoustics  (20)
  • Ocean bottom  (12)
  • Sediment transport  (8)
  • Remote sensing
  • Woods Hole Oceanographic Institution  (39)
  • Elsevier  (6)
  • American Institute of Physics (AIP)
  • 2015-2019  (45)
  • 1
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    The Lusi drone: A multidisciplinary tool to access extreme environments (2019)
    Elsevier
    Details
    Publication Date: 2021-06-15
    Description: Extreme and inaccessible environments are a new frontier that unmanned and remotely operated ve-hicles can today safely access and monitor. The Lusi mud eruption (NE Java Island, Indonesia) representsone of these harsh environments that are totally unreachable with traditional techniques. Here boilingmud is constantly spewed tens of meters in height and tall gas clouds surround the 100 m wide activecrater. The crater is surrounded by a ~600 m diameter circular zone of hot mud that prevents anyapproach to investigate and sample the eruption site. In order to access this active crater we designedand assembled a multipurpose drone.The Lusi drone is equipped with numerous airborne devices suitable for use on board of other mul-ticopters. During the missions, three cameras can complete 1) video survey, 2) high resolution photo-grammetry of desired and preselected polygons, and 3) thermal photogrammetry surveys with infra-redcamera to locate hotfluids seepage areas or faulted zones. Crater sampling and monitoring operationscan be pre-planned with aflight software, and the pilot is required only for take-off and landing. A winchallows the deployment of gas, mud and water samplers and contact thermometers to be operated withno risk for the aircraft. During the winch operations (that can be performed automatically), the aircrafthovers at a safety height until the tasks controlled by the winch-embedded processor are completed. Thedrone is also equipped with GPS-connected CO2and CH4sensors. Gridded surveys using these devicesallowed obtaining 2D maps of the concentration and distribution of various gasses over the area coveredby theflight path.The device is solid, stable even with significant wind, affordable, and easy to transport. The Lusi dronesuccessfully operated during several expeditions at the ongoing active Lusi eruption site and proved to bean excellent tool to study other harsh or unreachable sites, where operations with more conventionalmethods are too expensive, dangerous or simply impossible
    Description: LUSI LAB project, PI A. Mazzini; esearch Council of Norway through itsCenters of Excellence funding scheme, Project Number 223272; BPLS (Badan Penanggulangan Lumpur Sidoarjo, Sidoarjo Mudflow Management Agency)
    Description: Published
    Description: 26-37
    Description: 2IT. Laboratori sperimentali e analitici
    Description: JCR Journal
    Keywords: Lusi mud eruption ; Drone-UAV ; Multirotor ; Remote sampling ; Remote sensing ; Indonesia ; 05.04. Instrumentation and techniques of general interest
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 2
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    Retrieval and intercomparison of volcanic SO2 injection height and eruption time from satellite maps and ground-based observations (2018)
    Elsevier
    Details
    Publication Date: 2021-03-19
    Description: Syneruptive gas flux time series can, in principle, be retrieved from satellite maps of SO2 collected during and immediately after volcanic eruptions, and used to gain insights into the volcanic processes which drive the volcanic activity. Determination of the age and height of volcanic plumes are key prerequisites for such calculations. However, these parameters are challenging to constrain using satellite-based techniques. Here, we use imagery from OMI and GOME-2 satellite sensors and a novel numerical procedure based on back-trajectory analysis to calculate plume height as a function of position at the satellite measurement time together with plume injection height and time at a volcanic vent location. We applied this new procedure to three Etna eruptions (12 August 2011, 18 March 2012 and 12 April 2013) and compared our results with independent satellite and ground-based estimations. We also compare our injection height time-series with measurements of volcanic tremor, which reflects the eruption intensity, showing a good match between these two datasets. Our results are a milestone in progressing towards reliable determination of gas flux data from satellite-derived SO2 maps during volcanic eruptions, which would be of great value for operational management of explosive eruptions.
    Description: 1) European Research Council under the European Union's Seventh Framework Programme (FP/2.007-2013)/ERC Grant Agreement no. 279802, project 283 CO2Volc. 2) MEDiterranean SUpersite Volcanoes 280 (MED-SUV) WP 3.3.3
    Description: Published
    Description: 79-91
    Description: 5V. Dinamica dei processi eruttivi e post-eruttivi
    Description: JCR Journal
    Keywords: Volcanic SO2 ; Trajectory modelling ; Remote sensing ; Volcanic tremor ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 3
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    Survey of shoreline structures, Popponesset Beach, MA (2017)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-25
    Description: The structures along a 12 km section of the shoreline of Cape Cod, Mass., were evaluated for condition and effectiveness at protecting the coast. Structures in the area include groins, jetties, revetments, and seawalls; each has been located, photographed and described. The region has been subject to erosion in recent years, including the loss of a 1 km section of barrier spit. The role of shoreline structures in controlling or enhancing the erosion was examined as part of a larger study of coastal processes in the area. The shoreline structures serve two primary functions: beach enhancement and protection of the bluffs from erosion. The structures• effects on bluffs and beaches in their immediate vicinity (approximately lOOm along the coastline to the north and south of the structure) are detailed in this report. Seawalls generally protect the cliffs into which they are built without enhancing erosion of surrounding bluffs, though the bluffs are protected at the expense of the beaches in the central area (Meadow Point). Large scale changes in beach configuration are not primarily caused by local, small-scale structures, but rather by a more regional paucity of sand input into the system. This scarcity is caused in part by large jetties controlling inlet flows to Waquoit Bay, which impedes free transport of sand into the area.
    Description: Funding was provided through a Massachusetts Coastal Zone Management Program Community Assistance Grant by the Town of Mashpee and through NOAA, Office of Sea Grant under Grant NA80AA-D-00077 (RB-40).
    Keywords: Shore protection ; Sediment transport
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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  • 4
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    The Woods Hole Oceanographic Institution digital ocean bottom hydrophone instrument : technical report (2017)
    Woods Hole Oceanographic Institution
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    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
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  • 5
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    Inner-shelf ocean dynamics and seafloor morphologic changes during Hurricane Sandy (2017)
    Elsevier
    Details
    Publication Date: 2022-05-25
    Description: This paper is not subject to U.S. copyright. The definitive version was published in Continental Shelf Research 138 (2017): 1-18, doi:10.1016/j.csr.2017.02.003.
    Description: Hurricane Sandy was one of the most destructive hurricanes in US history, making landfall on the New Jersey coast on October 30, 2012. Storm impacts included several barrier island breaches, massive coastal erosion, and flooding. While changes to the subaerial landscape are relatively easily observed, storm-induced changes to the adjacent shoreface and inner continental shelf are more difficult to evaluate. These regions provide a framework for the coastal zone, are important for navigation, aggregate resources, marine ecosystems, and coastal evolution. Here we provide unprecedented perspective regarding regional inner continental shelf sediment dynamics based on both observations and numerical modeling over time scales associated with these types of large storm events. Oceanographic conditions and seafloor morphologic changes are evaluated using both a coupled atmospheric-ocean-wave-sediment numerical modeling system that covered spatial scales ranging from the entire US east coast (1000 s of km) to local domains (10 s of km). Additionally, the modeled response for the region offshore of Fire Island, NY was compared to observational analysis from a series of geologic surveys from that location. The geologic investigations conducted in 2011 and 2014 revealed lateral movement of sedimentary structures of distances up to 450 m and in water depths up to 30 m, and vertical changes in sediment thickness greater than 1 m in some locations. The modeling investigations utilize a system with grid refinement designed to simulate oceanographic conditions with progressively increasing resolutions for the entire US East Coast (5-km grid), the New York Bight (700-m grid), and offshore of Fire Island, NY (100-m grid), allowing larger scale dynamics to drive smaller scale coastal changes. Model results in the New York Bight identify maximum storm surge of up to 3 m, surface currents on the order of 2 ms−1 along the New Jersey coast, waves up to 8 m in height, and bottom stresses exceeding 10 Pa. Flow down the Hudson Shelf Valley is shown to result in convergent sediment transport and deposition along its axis. Modeled sediment redistribution along Fire Island showed erosion across the crests of inner shelf sand ridges and sedimentation in adjacent troughs, consistent with the geologic observations.
    Description: This research was funded by the U.S. Geological Survey (USGS), Coastal and Marine Geology Program, and conducted by the Coastal Change Processes Project. This research was supported in part by the Department of the Interior Hurricane Sandy Recovery program.
    Keywords: Shoreface connected sand ridges ; Sediment transport ; Fire Island, NY ; Hurricane Sandy ; Inner shelf ; Numerical modeling
    Repository Name: Woods Hole Open Access Server
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  • 6
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    Proceedings of a Workshop on Coastal Zone Research in Massachusetts : (November 27-28, 1978) (2018)
    Woods Hole Oceanographic Institution
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    Publication Date: 2022-05-25
    Description: A workshop on Coastal Zone Research held on 27 and 28 November, 1978, at Woods Hole Oceanographic Institution, brought together fifty researchers actively studying physical processes in the Massachusetts coastal zone (Appendix 1). Presentations were given by nearly half of the participants to acquaint other researchers with their past, present, and future research interests. Summaries of the presentations are included in Appendix 3. Although the scope of the workshop was narrow, emphasizing only selected aspects of coastal zone research, it represented an important attempt to assess our knowledge of physical processes in the nearshore, and to encourage cooperation and communication between scientists. Two sets of recommendations evolved from the workshop. The first set recommends ways to facilitate scientist - user communication, and provide more rapid dissemination of coastal research results. The second set describes areas of future research in the Massachusetts coastal zone. Neither of the two sets of recommendations is comprehensive: they reflect primarily the opinions and judgements of the workshop participants. Because of the interest expressed by the participants, the workshop will be held on an annual basis until the need for such meetings disappears. Future workshops may have specific goals, e.g. preparation of coastal erosion maps or historical shoreline change maps. Future meetings may also have more state, federal, and local governmental participants in an effort to foster scientist - user communications. The workshop was co-sponsored by the Woods Hole Sea Grant Program and Woods Hole Oceanographic Institution. The Woods Hole Sea Grant Program has offered to co-sponsor future Workshops on Coastal zone Research as part of their continued interest in the Massachusetts coastal zone.
    Description: Prepared for the Department of Commerce, NOAA Office of Sea Grant under Grant 04-8-M01-149 and the Institution's Marine Policy and Ocean Management Program.
    Keywords: Coastal zone management ; Beach erosion ; Sediment transport
    Repository Name: Woods Hole Open Access Server
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  • 7
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    AFRAME : a video animation capability for displaying FINDIF numerical model output (2016)
    Woods Hole Oceanographic Institution
    Details
    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
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  • 8
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    Progress report on the development of the seafloor borehole array seismic system (phase II) : July 14, 1992 to January 31, 1996 (2016)
    Woods Hole Oceanographic Institution
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    Publication Date: 2022-05-25
    Description: The Seafloor Borehole Array Seismic System (SEABASS) was originally developed to record autonomously on the seafloor the signals received on a four-sonde three-component borehole geophone array in the VLF band (2-50Hz)(Stephen eta!., 1994). The system is designed to use the wireline re-entry capability (Spiess, 1993; Spiess eta!., 1992) to install and retrieve the seafloor instrumentation (Figures 1 and 2). Following the successful demonstration of this technology on the LFASE (Low Frequency Acoustic-Seismic Experiment) project in September 1989, it was decided to extend the capability to broadband (1000sec-5Hz) borehole seismometers which could be used for permanent seafloor seismic observatories in the Ocean Seismic Network (Orcutt and Stephen, 1993; Purdy and Dziewonski, 1988; Purdy and Orcutt, 1995; Stephen, 1995; Sutton and Barstow, 1990; Sutton eta!., 1988; Sutton eta!., 1965). The Broadband Borehole Seismic System (B3S2) is the prototype system for permanent broadband borehole seismic observatories on the seafloor. It has three major components: i) a broadband borehole seismometer, the Teledyne 54000, modified for seafloor operations by Scripps-IGPP; ii) the re-entry system provided by Scripps-MPL; and iii) the seafloor recording system developed by WHO I. Because of the similarity of the seafloor recording system to SEABASS we have named this new system SEABASS-ll. This report discusses the development of SEABASS-Il at WHOI in the period from July 14, 1992 to January 31, 1996. The motivation for the project and a work statement are contained in WHOI proposals 7016 and 7016.1. This report is a collection of documentation prepared while the work was being carried out. Some of the issues discussed in early memos were subsequently changed. Modifications and further testing of SEABASS-ll, as well as final system integration tests with the borehole andreentry systems (both of which are also still being modified and tested) have still to be carried out in preparation for the OSN Pilot Experiment Cruise in Spring 1997. This is a preliminary report only and presents work in progress. It will be useful to the engineering team as a historical reference of the sequence of events in the development of SEABASS-ll but it should not be considered as a technical manual for the instrumentation.
    Keywords: Seismology ; Borehole gravimetry ; Ocean bottom ; Oceanographic instruments
    Repository Name: Woods Hole Open Access Server
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  • 9
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    Satellite image processing for the Agulhas Retroflexion region (2015)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-25
    Description: In order to analyze the Advanced Very High Resolution Radiometer satellite data from South Africa, a software package has been written. Methodology and algorithms are described which create geometrically corrected registered satellite images over the Agulhas Retroflexion region. Also discussed are programs to overlay latitude and longitude lines, ship tracks, and ancillary data. A method of masking the land and compositing images for cloud removal is also described.
    Description: Funding was provided by the Office of Naval Research under contract Numbers N00014-82-C-0019, NR 083-004, N00014-85-C-001, NR 083-004, and N00014-87-K-0007, NR 083-004.
    Keywords: Remote sensing ; Electronic data processing
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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  • 10
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    Tripod modification of sphincter corer : construction, operation, core extrusion and sampling efficiency (2017)
    Woods Hole Oceanographic Institution
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    Publication Date: 2022-05-25
    Description: A 21-cm diameter sphincter corer (Burke, 1968) has been modified by mounting it in a tripod frame. This modification results in more dependable recovery of undisturbed surficial sediment and greater penetration into firm sediment. The device is useful in water depths from 2-6000 m, is adaptable for use on small boats, is very easily employed on large research vessels, and can be readily disassembled for more convenient transporting and storing.
    Description: Funding was provided by the U.S. Department of Energy under Contract EY-76-C-3563, Sandia National Laboratory under Contract 37/3164 and the U.S. Nuclear Regulatory Commission under Contract NRC- 04-76-349.
    Keywords: Underwater drilling ; Ocean bottom ; Core drilling
    Repository Name: Woods Hole Open Access Server
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  • 11
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    Signal and noise levels in numerical scattering chamber snapshots (2017)
    Woods Hole Oceanographic Institution
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    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
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  • 12
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    Evaluation of video-based linear depth inversion performance and applications using altimeters and hydrographic surveys in a wide range of environmental conditions (2018)
    Elsevier
    Details
    Publication Date: 2022-05-25
    Description: This paper is not subject to U.S. copyright. The definitive version was published in Coastal Engineering 136 (2018): 147-160, doi:10.1016/j.coastaleng.2018.01.003.
    Description: The performance of a linear depth inversion algorithm, cBathy, applied to coastal video imagery was assessed using observations of water depth from vessel-based hydrographic surveys and in-situ altimeters for a wide range of wave conditions (0.3 〈 significant wave height 〈 4.3 m) on a sandy Atlantic Ocean beach near Duck, North Carolina. Comparisons of video-based cBathy bathymetry with surveyed bathymetry were similar to previous studies (root mean square error (RMSE) = 0.75 m, bias = −0.26 m). However, the cross-shore locations of the surfzone sandbar in video-derived bathymetry were biased onshore 18–40 m relative to the survey when offshore wave heights exceeded 1.2 m or were greater than half of the bar crest depth, and broke over the sandbar. The onshore bias was 3–4 m when wave heights were less than 0.8 m and were not breaking over the sandbar. Comparisons of video-derived seafloor elevations with in-situ altimeter data at three locations onshore of, near, and offshore of the surfzone sandbar over ∼1 year provide the first assessment of the cBathy technique over a wide range of wave conditions. In the outer surf zone, video-derived results were consistent with long-term patterns of bathymetric change (r2 = 0.64, RMSE = 0.26 m, bias = −0.01 m), particularly when wave heights were less than 1.2 m (r2 = 0.83). However, during storms when wave heights exceeded 3 m, video-based cBathy over-estimated the depth by up to 2 m. Near the sandbar, the sign of depth errors depended on the location relative to wave breaking, with video-based depths overestimated (underestimated) offshore (onshore) of wave breaking in the surfzone. Wave speeds estimated by video-based cBathy at the initiation of wave breaking often were twice the speeds predicted by linear theory, and up to three times faster than linear theory during storms. Estimated wave speeds were half as fast as linear theory predictions at the termination of wave breaking shoreward of the sandbar. These results suggest that video-based cBathy should not be used to track the migration of the surfzone sandbar using data when waves are breaking over the bar nor to quantify morphological evolution during storms. However, these results show that during low energy conditions, cBathy estimates could be used to quantify seasonal patterns of seafloor evolution.
    Description: This research was funded by the U.S. Army Corps of Engineers Coastal Field Data Collection Program, the Deputy Assistant Secretary of the Army for Research and Technology under ERDC's research program titled “Force Projection Entry Operations, STO D.GRD.2015.34”, the U.S. Naval Research Laboratory base program from the Office of Naval Research, a Vannevar Bush Faculty Fellowship funded by the Assistant Secretary of Defense for Research and Engineering, and the National Science Foundation.
    Keywords: Remote sensing ; Beach morphology ; Depth inversion ; Bathymetry estimation ; Video imaging ; Surfzone
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  • 13
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    Tests of the broadband borehole seismic system (B³S²) at Scripps IGPP and the Pinon Flat Observatory : October 1994 to June 1995 (2016)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: The broadband borehole seismic system (B3S2) is being developed as one component of the Ocean Seismic Network (OSN) Pilot Experiment which will be carried out at the OSN-1 Site off Hawaii in Winter 1998. The other major instruments being developed for the experiment are a Broadband Ocean Bottom Seismometer and a Shallow Buried Broadband Ocean Bottom Seismometer. B3S2 consists of four major components: 1) a borehole sonde with a re-entry guide, Teledyne 54000 broadband seismometer, and REFTEK digitizing system, 2) a seafloor acquisition and recording system (SEABASS), 3) a control vehicle for deploying the sonde in a borehole, and 4) shipboard command and control electronics. The deployment system is very similar to the SEABASS configuration used on LFASE (Stephen eta!, 1994). The purposes of the tests at Pinon Flat were: 1) to integrate the borehole sonde and seafloor and shipboard electronics which had been constructed by different groups: WHOI and SIO/IGPP; 2) test the combined subsystem in a wet borehole environment using actual cables and simulating seafloor conditions; and 3) acquire seismic ambient noise and earthquake data over approximately a three month period for comparison with known stations at the Pinon Flat Observatory.
    Description: This work was carried out under NSF Grants No. OCE-91-18943 and OCE No. OCE-95-05730: "A Broadband Borehole Seismometer for the Deep Ocean - Development and Land Testing"
    Keywords: Seismology ; Borehole gravity meters ; Ocean bottom ; Oceanographic instruments
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  • 14
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    Ocean Bottom Seismometer Augmentation in the North Pacific (OBSANP) - cruise report (2015)
    Woods Hole Oceanographic Institution
    Details
    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
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  • 15
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    Short-term variability in nighttime scattering strength levels at one site in the eastern Algero-Provençal Basin (2016)
    Woods Hole Oceanographic Institution
    Details
    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
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  • 16
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    Arctic acoustic tomography : MIZEX 84 (2016)
    Woods Hole Oceanographic Institution
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    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
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  • 17
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    A compilation of digitized satellite imagery of the Gulf Stream (1982, 1983, and 1985) (2015)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: Ninety plots of digitized temperature boundaries from infared satellite images of the Gulf Stream along with corresponding image snapshots were compiled to determine stream width propagation speed. The satellite images are from the years 1982, 1983, and 1985 and are often of consecutive days. In this report, these images and digitized plots are presented.
    Description: Funding was provided by the Office of Naval Research through contract Number N00014-87-K-0007, and by the National Science Foundation under grant Numbers OCE 87-00601 and OCE 85-10828.
    Keywords: Oceanography ; Ocean temperature ; Remote sensing
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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    Capturing coastal water clarity variability with Landsat 8 (2019)
    Elsevier
    Details
    Publication Date: 2022-05-26
    Description: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Luis, K. M. A., Rheuban, J. E., Kavanaugh, M. T., Glover, D. M., Wei, J., Lee, Z., & Doney, S. C. Capturing coastal water clarity variability with Landsat 8. Marine Pollution Bulletin, 145, (2019): 96-104, doi: 10.1016/j.marpolbul.2019.04.078.
    Description: Coastal water clarity varies at high temporal and spatial scales due to weather, climate, and human activity along coastlines. Systematic observations are crucial to assessing the impact of water clarity change on aquatic habitats. In this study, Secchi disk depths (ZSD) from Boston Harbor, Buzzards Bay, Cape Cod Bay, and Narragansett Bay water quality monitoring organizations were compiled to validate ZSD derived from Landsat 8 (L8) imagery, and to generate high spatial resolution ZSD maps. From 58 L8 images, acceptable agreement was found between in situ and L8 ZSD in Buzzards Bay (N = 42, RMSE = 0.96 m, MAPD = 28%), Cape Cod Bay (N = 11, RMSE = 0.62 m, MAPD = 10%), and Narragansett Bay (N = 8, RMSE = 0.59 m, MAPD = 26%). This work demonstrates the value of merging in situ ZSD with high spatial resolution remote sensing estimates for improved coastal water quality monitoring.
    Description: This work was supported by the John D. and Catherine T. MacArthur Foundation (grant 14-106159-000-CFP) and by the National Science Foundation grant DGE 1249946, Integrative Graduate Education and Research Traineeship (IGERT): Coasts and Communities – Natural and Human Systems in Urbanizing Environments. Lastly, we are indebted to the Massachusetts Water Resources Authority, Buzzards Bay Coalition, Provincetown Center for Coastal Studies, Narragansett Bay Commission, and the numerous citizen scientists responsible for collecting the in situ measurements used in this study. Comments and suggestions from our anonymous reviewer were greatly appreciated.
    Keywords: Water quality ; Secchi disk depth ; Remote sensing ; Landsat
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  • 19
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    Technical progress report : advanced marine technology 1 August 1972 - 31 January 1973 (2019)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: The work sponsored by ARPA at Woods Hole Oceanographic Institution is having an impact on efforts by those not directly involved in the projects both within and without the Institution. The navigation system being developed for submersible/mother ship has been recognized as a very useful system by members of the Geology/Geophysics Department and the Department of Physical Oceanography. Each department is now developing their own system based on the work already completed by the Ocean Engineering Department under the ARPA contact. Through the ARPA contract ComPhibLant (specifically ComPhibRonTen) was shown some of the advantages of doing something new about small boat and heavy object handling at sea and this program is expected to have some direct effect upon methods they will use in the future. Although the project concerned with developing biological equipment for deep sea work has not continued as part of the ARPA program, the seed was succssfully sown and several items are being developed at the Institution under separate funding. All the projects continued at a fair pace but not without some problems. The Deep Sea Rock Drill had some minor setbacks during operations with ALVIN, and the Air-Sea System (Long Range Ech-Ranging) project was hampered by a faulty engine aboard the air craft. Summaries of progress are given immediately below and more detail is available in the individual reports further on.
    Description: Prepared for the Office of Naval Research under Contract N00014-71-C00284; NR 293-008.
    Keywords: Oceanographic submersibles ; Oceanographic buoys ; Submarine geology ; Underwater acoustics ; Sonar
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  • 20
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    Remote acoustic sensing of oceanic fluid and biological processes (2018)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: High frequency acoustic backscattering systems are being used in monostatic modes to evaluate the use of acoustic techniques to detect and study a variety of fluid processes in the oceanic environment. A short outline of those research programs actively evaluating and using acoustic techniques is presented, followed by a detailed review of this investigator's program. This program uses a multifrequency high frequency acoustic system to study a variety of processes including turbulent mixing, air-sea interactions, internal waves, interleaving water masses, natural particulate dispersion and distribution, the dispersion of particulates associated with deep ocean disposal of industrial chemical waste, and biological response to a variety of stimulae including fluid motion, predators, and oceanographic instrumentation. Graphic acoustic data records of several of the above phenomena are described.
    Description: Prepared for the Office of Naval Research under Contract N00014-77-C-0196; NR 083-004, for the National Oceanic & Atmospheric Administration under Grants NA79AA-D-00030 (Ocean Dumping Program) and NA79AA-D-00102 (Office of Sea Grant) and for the National Science Foundation under Grant OCE 77-08682.
    Keywords: Underwater acoustics ; Oceanography ; Marine biology
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  • 21
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    Assessment of seabed seismic systems (2018)
    Woods Hole Oceanographic Institution
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    Publication Date: 2022-05-26
    Description: This project was initiated to accomplish the necessary research and documentation of existing seismic techniques and systems for the study of sediments and sedimentary structures in the oceans. In this respect , it is an 'inventory' of methods and techniques for looking at small-scale features or changes in structures lying from 10 to 1000 m beneath the sea floor. It attempts to assess the vertical and lateral resolution capabilities of existing and technically feasible seismic systems. Some of the questions posed are: how closely can we determine vertical variation such as sediment layer thickness and vertical variation with depth; also lateral coherence or its disruption by such agents as facies changes, thinning or thickening, slumping, faulting; the nature of the basement structure, its areal coherence, velocity structure and associated anomalies?
    Description: Prepared for the Sandia Laboratories under Contract 13-9944.
    Keywords: Seismology ; Ocean bottom
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  • 22
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    The geographic variation of midwater sound-scattering(u) (2018)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: Originally issued as Reference No. 66-10, series later renamed WHOI-
    Description: It is suggested in this report that the intensity of midwater sound-scattering in the ocean varies from point to point as the abundance of marine life varies. Several charts depicting variations in the abundance of marine life are given, from which estimates of the intensity of sound-scattering can be made.
    Description: Submitted to the Offiae of Naval Researah under Contraat Nonr-4029(00JNR 260-101.
    Keywords: Echo scattering layers ; Underwater acoustics
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  • 23
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    A dynamical interpretation of low frequency motions near very rough topography : the Charlie Gibbs Fracture Zone (2018)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: Also published as: Journal. of Marine Research 38 (1980): 215-248
    Description: As a sequel to Schmitz and Hogg (1978), nine-month moored observations of current and temperature from the Charlie Gibbs Fracture Zone are further described, and then interpreted in terms of low frequency quasigeostrophic motions. Large vertical and horizontal changes are observed in the variance of both mean and fluctuating components. It is demonstrated that these changes could be associated with the (complex) nature of the topography. With regard to the mean flow, it is shown through an advective model that the topography is sufficiently steep to force this motion to closely follow isobaths. Time-dependent motions for periods from 2 to 96 days are described using the technique of empirical orthogonal functions. The most energetic mode is always bottom trapped, with flow oriented along isobaths at lower frequencies and approaching equipartition of along- and cross-isobath motions at higher frequencies. At the lowest frequencies a second mode which increases upward in energy is also judged significant, while for periods shorter than 3.6 days the second mode is again highly bottom trapped. We interpret these motions using linear wave theory. There is relatively close correspondence between theory and observation when the effects of both large- and small-scale topographic features are included in the model calculations. In addition to the usual topographic wave, the abrupt slope changes on the north wall allow for a baroclinic fringe mode with a ncar bottom node at low frequencies and small-scale bottom corrugations force highly bottom trapped waves above the smooth slope cut-off frequency.
    Description: Prepared for the Office of Naval. Research under Contract N00014-76-C-0197; NR 083- 400.
    Keywords: Ocean bottom ; Submarine topography ; Charles Gibbs Fracture Zone
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  • 24
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    A technique for measuring the plane-wave reflection coefficient of the ocean bottom (2018)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: Also published as: Journal of the Acoustical Society of America 68 (1980): 602-612
    Description: A new technique for the measurement of the plane-wave reflection coefficient of a horizontally stratified ocean bottom is described. It is based on the exact Hankel transform relationship between the reflection coefficient and the bottom reflected field due to a point source. The method employs a new algorithm for the numerical evaluation of the Hankel transform which is based on the "projection-slice" theorem for the two-dimensional Fourier transform. The details of the algorithm are described in the companion paper. Although the algorithm is applied to the case of an isovelocity ocean, the general theory for measuring the plane-wave reflection coefficient in a refracting ocean is developed. The technique provides information about the reflection coefficient, not only for real incident angles, _but also for complex angles, thus potentially providing substantial additional structural information about the bottom. The method is shown to yield excellent results with synthetically generated data for the cases of a hard bottom and slow isovelocity bottom.
    Description: Prepared for the Office of Naval Research under Contracts N00014-77-C-0196 and N00014-75-C-0951; NR 049-328.
    Keywords: Ocean bottom ; Hankel functions ; Reflectance
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  • 25
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    The contribution of normal modes in the bottom to the acoustic field in the ocean (2018)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: Also published as: Journal of the Acoustical Society of America 68 (1980): 602-612
    Description: The effects of normal modes in the bottom on the acoustic field in the ocean are examined. The ocean bottom model consists of a slow isovelocity layer overlying an isovelocity half-space to simulate the characteristic sound velocity drop at the water-bottom interface. Attention is focused on the perfectly trapped modes which are excited in the layer by inhomogeneous waves emitted by a point source in the water column. The relative normal mode contribution to the total acoustic field in the water is calculated analytically for a near-bottom source/receiver geometry and evaluated for representative ocean bottom examples. It is shown that, for combined source/receiver heights less than a wavelength, the field is dominated by the leaky mode contribution at short ranges ( $ 2 km) and the trapped mode contribution at long ranges ( ~ 2 km). For fixed bottom parameters, the trapped mode contribution increases exponentially with decreasing combined source/receiver height. It is also shown that, for a fixed layer wavenumber-thickness product and fixed layer sound speed, the leaky mode fields at different frequencies are approximately range-scaled versions of the same field.
    Description: Prepared for the Office of Naval Research under Contract N000 14-77-C-0196.
    Keywords: Ocean bottom ; Acoustic models
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  • 26
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    Sound channel propagation through eddies southeast of the Gulf Stream (2018)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: Also published as: Journal of the Acoustical Society of America 68 (1980): 1750-1767
    Description: Acoustical signals at 270 Hz from SOFAR floats drifting in the region southeast of the Gulf Stream were recorded during most of 1975 from a near axis sound channel hydrophone near Bermuda. The amplitude levels received exhibit a large increase (12–18 dB) commencing about 24 July, following a long period (March to July) of relatively lower peak level amplitudes. A major part of the increase can be attributed to the influence of a large cyclonic eddy (Gulf Stream ring) that passed slowly between the SOFAR floats and Bermuda. Such an eddy produces a large sound speed anomaly that extends to depths below the axis of the sound channel. On 24 July, two SOFAR floats were known to have approximately the same sound transmission path through the edge of the large eddy. The sound transmission peaks occur when no ocean eddy is between the SOFAR floats and the receiver. Their spacing shows they occur at regular refraction caustics in the sound channel. When the sound transmission path passes through an eddy, these transmission focal distances are shifted to greater range and the signal level may be greatly enhanced. The decrease of caustic peak intensities with range is 5 dB per double distance, and this agrees with theory. Several different levels of peak acoustic intensity occur and these result from two float depths and oceanic thermocline oscillations.
    Description: Prepared for the Office of Naval Research under Contract N00014-74-C-0262; NR 083-004·.
    Keywords: Underwater acoustics ; Eddies
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  • 27
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    Multipath variability due to the Gulf Stream (2018)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: Also published as: Journal of the Acoustical Society of America 69 (1981): 982-988
    Description: A phase-coded signal with 64-ms resolution was transmitted at 10-min intervals for a 19-day period over two ~300-km ranges. The acoustic source was moored at 2000-m depth northwest of Bermuda. One receiver was moored at 2000-m depth to the northeast of the source and the other receiver was bottom mounted at ~1000- m depth near Bermuda. The large (~0.6 s) travel time change at the Bermuda receiver is probably due in large part to motion of the source mooring in the presence of currents. The multipath arrival pattern at the moored receiver undergoes significant modification due to the presence of a southern meander of the Gulf Stream which intersects this transmission path.
    Description: Prepared for the Office of Naval Research under Contract N00014-77-C-0196 and NORDA contract N00014-79-C-0071.
    Keywords: Underwater acoustics
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  • 28
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    A towed, multi-frequency H.F. sonar system for scattering and ocean dynamics studies (2018)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: The system described provides wide operational flexibility at any operating frequency from 5 kHz to over 800 kHz (except for a small band around 455 kHz) limited mainly by the availability of transducers. Variable pulse width, variable receiver bandwidth, low receiver noise, various time variable gain functions and wide system dynamic range characterized the system. Built-in time-sharing controls maximize flexibility of graphics display on either dry-paper or fibre-optic CRT recorders.
    Description: Prepared for the NORDA under Contract N00014-77-C-0196; and for the National Oceanic and Atmospheric Administration under Grant 04-8-MO1-43.
    Keywords: Underwater acoustics ; Sonar ; Oceanographic instruments ; Scientific apparatus and instruments
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  • 29
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    The Hebble report : being the proceedings of the Workshop on a High Energy Benthic Boundary Layer Experiment held at the Keystone Center for Continuing Education, Keystone, Colorado, March 13-17, 1978 (2018)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: From the Foreward: Despite the currently fashionable use of the word "interdisciplinary" to describe research projects, few such efforts are known among oceanographers studying the benthic boundary layer (BBL). In order to encourage discussions among the diverse groups interested in deep-sea BBL problems and to begin the coordination of experiments, the Office of Naval Research (Code 480) has recently sponsored two workshops. In March 1977 a group of investigators with ONR-supported projects met at the Naval Ocean Research and Development Activity (NORDA) in Bay St. Louis, Mississippi to define scientific and geographic areas of interest. A large group of investigators met for a more ambitious workshop at the Keystone Conference Center, Keystone, Colorado, from March 13 to 17, 1978. This report summarizes the deliberations of that second workshop.
    Description: Prepared for the Office of Naval Research under Contract N00014-74-C0262, NR083-004
    Keywords: Ocean bottom ; Benthos
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  • 30
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    Remote acoustic monitoring of natural suspensate distributions, active suspensate resuspension, and slope/shelf water intrusions (2018)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: Also published as Journal of Geophysical Research, Vol. 83, No. C8, 1978, pp. 4062-4068
    Description: Acoustic data, transmissometer data, and calculations are presented which indicate that high-frequency acoustic backscattering systems can become a valuable tool in the remote monitoring of suspended particle distributions and active resuspension areas. Data are also presented which show that acoustic backscattering systems can be used to remotely detect slope/shelf water frontal zones. Towed acoustic systems should be able to map the extent of the frontal zone and add significantly to the understanding of frontal zone processes.
    Description: Prepared for the Naval Oceanic Research and Development Activity under Contract N00014-77-C-0196.
    Keywords: Underwater acoustics ; Oceanographic instruments
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  • 31
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    Flow structures of the benthic ocean (2018)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: Also published as: Journal of Geophysical Research 85 (1980): 469-484
    Description: Three-dimensional structure of the near-bottom density field was observed with a towed yo-yoing profiler and a fixed current/temperature measuring array on the Hatteras abyssal plain. A great variety of structures were seen. Immediately above the bottom a well-mixed bottom layer extends vertically 5-60 m, with less than 1 m°C potential temperature change. This mixed layer is often capped by a region of strong vertical potential temperature gradient, with up to 100-m°C potential temperature change in -10 m. The boundary layer may be uniform for 10 km or exhibit a bottom temperature gradient of up to 20 m°C/ km. Interior layers of nearly constant potential temperature and horizontal extent of 2-100 km are seen -25% of the time above the bottom mixed layer. When an interior layer is present, the bottom mixed layer is thinner. On many occasions an interior layer was seen to be horizontally continuous with the bottom mixed layer, suggesting formation of interior layers by detachment of the bottom mixed layer. A benthic front was observed. Differential horizontal advection is required to explain the observed structures. Velocity fluctuations above I cph increase in energy near the bottom, presumably a signature of turbulence in the mixed layer;these fluctuations are modulated by the passage of structures observed in the moored record.
    Description: Prepared for the Office of Naval Research under Contract N00014-76-C-0197; NR 083-400 and for the National Science Foundation under Grant OCE 76-81190 ,
    Keywords: Hydraulics ; Ocean bottom
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  • 32
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    The crustal structure of the Kane fracture zone from seismic refraction studies (2018)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: Also published as: Journal of Geophysical Research 85 (1980): 3759-3777
    Description: A detailed seismic refraction experiment was carried out across the Kane Fracture Zone near 24°N, 44°W using explosive and air gun sound sources and eight ocean bottom hydrophone receivers. The shooting lines and receive rs formed a 'T' configuration across the fracture zone, with two receivers located about SO km apart in the fracture zone trough and the remaining six receivers positioned 25-30 km apart on either side of the fracture zone. The crustal thicknesses and velocities observed at the receivers located north and south of the Kane Fracture Zone fall within the range of those typically observed for normal oceanic crust. There is no convincing evidence for signficantly different crustal thicknesses or upper mantle velocities on either side of the fracture zone despite a 10-m.y. age difference. Anomalously thin crust is present beneath the Kane Fracture Zone trough with total crustal thicknesses of only 2-3 km, about half the thickness of normal oceanic crust. This crust is also characterized seismically by low compressional wave velocities (~4.0 km/s) at shallow depths and the absence of a normal layer 3 refractor. This anomalous crust extends over a width of a t least 10 km. Dense, high-velocity mantle type material may also exist at shallow depths beneath the adjacent Kane Fracture Zone ridge. Results from other geological and geophysical studies of fracture zones suggest that this type of crustal structure may by typical of many Atlantic fracture zones. We propose that the anomalously thin crust found within these fracture zones is a primary feature caused by the accretion of a thinner volcanic and plutonic layer within the fracture zone. This anomalous crust, which probably is restricted to a zone no wider than a typical transform fault valley (~10 km) in most cases, is inferred to consist of a few hundred meters of extrusive basalts and dikes overlying about 2 km of gabbro and metagabbro, possibly interbedded with ultramafics. This anomalously thin crustal section may be extensively fractured and brecciated at shallow levels by faulting in the active transform domain. A relatively narrow zone of thin crust within fracture zones can ex plain a number of geological and geophysical characteristics of fracture zones including the depth of the transform fault valley and the exposure of deep crustal and upper mantle rocks in the walls of fracture zones.
    Description: Prepared for the Office of Naval Research under Contract N00014-74-C0262 NR083-004.
    Keywords: Seismic refraction method ; Underwater acoustics
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  • 33
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    Tracking near surface drogues using an acoustic travel time technique in shallow, highly stratified water : problems and observations (2018)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: During July and August of 1980 near surface water velocities of Lake Huron were measured by tracking drogues, equipped with sonobuoys, using an acoustic travel time technique. Prior to these experiments difficulties associated with acoustic ray bending in the shallow, highly stratified environment were anticipated. Simple models were developed to predict the errors in drogue position and velocity determination resulting from ray bending. During the experiments round trip travel times of acoustic pulses transmitted between three bottom transponders and a transducer (lowered from a ship) were recorded. These combined with ray diagrams strongly suggested that, for a separation between the transducer and a bottom transponder of about 1.2 km, pulses which were detected first traveled by two paths, that of an inflected ray and that of a ray trapped beneath the thermocline. The error in position and velocity determination associated with these paths was 1 to 2%. Evidence also indicated that increased thermocline depth resulted in decreased tracking range.
    Description: Prepared for the Department of Energy under Contract DE-AC02-79EV10005 and for NOAA under Contract 03-5-022-26.
    Keywords: Underwater acoustics ; Acoustic drogue measurements
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  • 34
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    Acoustic environment of the Hatteras and Nares Abyssal Plains, western North Atlantic Ocean, determined from velocities and physical properties of sediment cores (2018)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: Also published as: Journal of the Acoustical Society of America 68 (1980): 1376-1390
    Description: Seventeen piston cores up to 13 m long were recovered from representative acoustic and lithologic environments of the Hatteras and Nares Abyssal Plains in the western North Atlantic. Compressional-wave velocities (corrected to in situ conditions) and bulk physical properties measured on the cores are used to characterize the acoustic framework of these areas. For correlation with conventional seismic data, wholecore averages of properties are a better index to the acoustic nature of abyssal plain sediments than properties of the upper few centimeters of the seafloor because (I) strong changes in lithofacies (and acoustic properties) occur over depth scales of tens of centimeters to meters in the sediment column, and (2) conventional seismic frequencies of 3.5 kHz or less sample these variations to subbottom depths of tens of meters and more. Wholecore properties are a function of the thickness and distribution of high-velocity silt and sand layers in the core; they vary in a complex fashion with proximity to the source of turbidity currents, distance from axial paths of turbidity-current flows, local and regional basin geometry, and seafloor slope. Thus strongly reflective seabed regions with numerous high-velocity layers are not restricted simply to near-source areas nor are weakly reflective seabed regions (clay sediments only) limited to "distal" areas. Whole-core properties show a good qualitative correlation to variations in 3.5-kHz reflection profiles, and 3.5-kHz echo character therefore provides a useful means of mapping general acoustic properties over large regions of abyssal plains.
    Description: Prepared for the Office of Naval Research under Contracts N00014-75-C-0210 and N00014-79-C-0071; NR 083-004.
    Keywords: Underwater acoustics ; Marine sediments
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  • 35
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    The HEBBLE II report : proceedings of the second annual workshop on the High Energy Benthic Boundary Layer Experiment held at the Keystone Center for Continuing Education, March 19-24, 1979 (2018)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: In 1978, the first Keystone Conference addressed the scientific problems of sediment transport in a high energy flow such as the Western Boundary Undercurrent. Sedimentologists, physical oceanographers, geologists, optical oceanographers, biologists, and ocean engineers planned a program called the High Energy Benthic Boundary Layer Experiment (HEBBLE) to measure ocean floor bed-forms, sediment properties, turbulent flow structure, suspended sediment concentrations and fluxes, mixed layer thickness, outer scale velocity and horizontal gradients of density in a carefully surveyed site yet to be selected. While measurements were suggested, specific instruments were not identified to implement them. It was encouraging that the scientists participating in the first HEBBLE Conference wanted to continue to plan a multi-disciplinary experiment. Because of the Jet Propulsion Laboratory's experience in management of planetary science experiments, autonomous instrumentation, image processing and data handling, we invited them to develop our experimental plan. Conferences were held in September at Woods Hole and November, 1978 at JPL to develop the instrumental ensemble. JPL involvement was concentrated on the extended deployment part of HEBBLE: the 6-month experiment. The March 20-23, 1979 conference brought JPL engineers and managers, HEBBLE scientists and PI's, ONR and NASA program managers together in Keystone, Colorado for presentation and discussion of the JPL program plan. This report summarizes the conference and includes reports by subcommittees of the conference on measurements and data sampling.
    Description: Prepared for the Office of Naval Research under Contract N00014-74-C-0262; NR 083-004.
    Keywords: High Energy Benthic Boundary Layer Experiment (HEBBLE) ; Sediment transport ; Ocean currents
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  • 36
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    An acoustic sensor of velocity for benthic boundary layer studies (2018)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: Also published in: Proceedings of the 8th International Colloquium on Ocean Hydrodynamics
    Description: The techniques of flow measurement which have been successful in laboratory studies of boundary layer turbulence are difficult to use in the ocean; and the current meters penerally used in the ocean are not suited to measuring bottom boundary layer flow . A suitable sensor for bottom turbulence measurements should measure vector components, respond linearly to these components, maintain an accurate zero point, disturb the flow negligibly or in a well predicted way, and sense a small enough volume to represent the important scales of the flow. We have constructed an acoustic travel time sensor in a configuration that will allow vector components of the flow to be measured with sufficient accuracy to compute Reynolds stress at a point 50 cm above the bottom. This sensor responds linearly to horizontal and vertical flows in flume tests. When the flow is neither horizontal nor vertical, the wake from one acoustic transducer may interfere with the measurement along one sensing path but there is sufficient redundancy in the determination to reject this path and still resolve the vector velocity. An instrument· using four of these sensors is being designed to measure Reynolds stress in the lower six meters of the ocean.
    Description: Prepared for the Office of Naval Research under Contract N00014-74-C-0262; NR 083-004.
    Keywords: Boundary layer ; Underwater acoustics ; Benthos
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  • 37
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    Ray calculations of ocean sound channels using a pocket programmable calculator and extended forms of the Hirsch-Carter mathematical model with tables of the incomplete beta function (2018)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: Formulas for curve fitting and ray computation using compound models made up of several different layers are presented. Examples of computation by pocket programmable calculator on two Sargasso Sea profiles, one from the center of a cold ring eddy are given. Necessary tables of the incomplete beta-function and calculator programs are included in a supplement.
    Description: Prepared for the Office of Naval Research under Contract N00014-77-C-0196.
    Keywords: Underwater acoustics ; Ocean sounds
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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    The design, logistics and installation of a SOFAR float tracking station at Grand Turk Island, B.W.I. (2018)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: The Mid-Ocean Dynamics Experiment (MODE) under the Office of the International Decade of Oceanography, National Science Foundation, included plans for the deployment of long-range SOFAR floats in a two degree square area approximately 400 miles Southwest of Bermuda. The floats are located by AFETR, MILS system hydrophones at Bermuda, Eleuthera and Puerto Rico. An additional station at Grand Turk Island, British West Indies, was requested to provide an expanded and more reliable location. In addition a spare installation was to be provided which could be installed within relatively short notice at Eleuthera or Puerto Rico if required. The design, logistical considerations and installation of the Grand Turk Island station are documented in this report.
    Description: Prepared for the National Science Foundation under Grant GX-32571.
    Keywords: Mid-Ocean Dynamics Experiment (MODE) ; Oceanographic buoys ; Underwater acoustics ; Oceanographic research stations
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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  • 39
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    Observations and 3D hydrodynamics-based modeling of decadal-scale shoreline change along the Outer Banks, North Carolina (2017)
    Elsevier
    Details
    Publication Date: 2022-05-26
    Description: This paper is not subject to U.S. copyright. The definitive version was published in Coastal Engineering 120 (2017): 78-92, doi:10.1016/j.coastaleng.2016.11.014.
    Description: Long-term decadal-scale shoreline change is an important parameter for quantifying the stability of coastal systems. The decadal-scale coastal change is controlled by processes that occur on short time scales (such as storms) and long-term processes (such as prevailing waves). The ability to predict decadal-scale shoreline change is not well established and the fundamental physical processes controlling this change are not well understood. Here we investigate the processes that create large-scale long-term shoreline change along the Outer Banks of North Carolina, an uninterrupted 60 km stretch of coastline, using both observations and a numerical modeling approach. Shoreline positions for a 24-yr period were derived from aerial photographs of the Outer Banks. Analysis of the shoreline position data showed that, although variable, the shoreline eroded an average of 1.5 m/yr throughout this period. The modeling approach uses a three-dimensional hydrodynamics-based numerical model coupled to a spectral wave model and simulates the full 24-yr time period on a spatial grid running on a short (second scale) time-step to compute the sediment transport patterns. The observations and the model results show similar magnitudes (O(105 m3/yr)) and patterns of alongshore sediment fluxes. Both the observed and the modeled alongshore sediment transport rates have more rapid changes at the north of our section due to continuously curving coastline, and possible effects of alongshore variations in shelf bathymetry. The southern section with a relatively uniform orientation, on the other hand, has less rapid transport rate changes. Alongshore gradients of the modeled sediment fluxes are translated into shoreline change rates that have agreement in some locations but vary in others. Differences between observations and model results are potentially influenced by geologic framework processes not included in the model. Both the observations and the model results show higher rates of erosion (∼−1 m/yr) averaged over the northern half of the section as compared to the southern half where the observed and modeled averaged net shoreline changes are smaller (〈0.1 m/yr). The model indicates accretion in some shallow embayments, whereas observations indicate erosion in these locations. Further analysis identifies that the magnitude of net alongshore sediment transport is strongly dominated by events associated with high wave energy. However, both big- and small- wave events cause shoreline change of the same order of magnitude because it is the gradients in transport, not the magnitude, that are controlling shoreline change. Results also indicate that alongshore momentum is not a simple balance between wave breaking and bottom stress, but also includes processes of horizontal vortex force, horizontal advection and pressure gradient that contribute to long-term alongshore sediment transport. As a comparison to a more simple approach, an empirical formulation for alongshore sediment transport is used. The empirical estimates capture the effect of the breaking term in the hydrodynamics-based model, however, other processes that are accounted for in the hydrodynamics-based model improve the agreement with the observed alongshore sediment transport.
    Description: This study was also supported by the United States Geological Survey Coastal Change Processes Project and Department of the Interior Hurricane Sandy Recovery program.
    Keywords: Sediment transport ; Shoreline change ; Alongshore transport ; Outer Banks; NC ; Aerial photography ; COAWST ; ROMS ; SWAN ; Three-dimensional ; Modeling ; Wave modeling ; Nearshore modeling ; Model coupling
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 40
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    Undersea acoustic research (2016)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: This is the final report of Contract N00014-77-C-0196 between the Woods Hole Oceanographic Institution and the Office of Naval Research for the contract period l January 1977 to 28 February 1983. This contract supported a broad program of research and development in underwater acoustics related to present and future Navy systems and requirements. The bulk of this contract research was conducted from 1977 to 1981, during which time the categories outlined below were all areas of active research. (Between 1981 and 1983 the contract remained in effect, although only in the area of bottom acoustics and at a reduced level.) The primary contract products are the published technical reports and papers listed below. These reports give detailed descriptions of the research work and the specialized techniques, methods, and instrumentation developed to support this research program. The final report contains a brief review of the program highlights and a bibliography of associated reports.
    Description: Funding was provided by the Office of Naval Research under Contract N00014-77-C-0196.
    Keywords: Underwater acoustics ; Signal processing
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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  • 41
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    Sediment transport in a tidal inlet (2017)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: Various aspects of sediment transport in and around natural, unstructured tidal inlets were investigated over the two year period of study. Concentrating on two tidal inlets (Nauset Inlet and Popponesset Inlet, Cape Cod, MA), and combining detailed field observations with numerical model studies of tidal flows in inlet/estuarine environments, several aspects of tidal inlet behavior have been clarified. In addition, field work has resulted in a number of technical publications of general utility to a wide spectrum of coastal research interest. Primary scientific items addressed in this study include: 1) diagnostic numerical model of generation and propagation of tidal non-liniarities in shallow estuarine channels; 2) effects of flow curvature on tidal inlet sediment transport; 3) definition of mechanisms by which tidal inlets migrate in a direction opposite to the net littoral drift direction; 4) hypothesis of a mechanism for rapid barrier spit growth in locations with low rates of littoral transport; 5) clarification of long-term patterns of sea-level rise in the United States to assess its role in tidal inlet/esturarine evolution; 6) historical descriptions of massive inlet migration at two study inlets as supporting evidence for the inlet modeling studies. Technical information generated by the study includes a description of a low-cost, reliable method to join nearshore electrical cables; description and intercomparison of instrumentation and analysis routines for estimating directional spectral parameters from wave gage data; and development of a field system and laboratory analysis package for preparing accurate bathymetric charts in shallow, nearshore regions, using microwave navigation and precision echo-sounding.
    Description: Funding was provided by the U.S. Army Research Office under Grant DAAG 29-81-K-0004 and the Department of Commerce, NOAA Office of Sea Grant under Grants NA79AA-D-00102 and NA80AA-D-00077.
    Keywords: Sediment transport ; Inlets
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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    Variability of sea-floor roughness within the Coastal Ocean Dynamics Experiment (CODE) region (2017)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: This report briefly summarizes the geological and biological data taken oft northern California before and during the Coastal Ocean Dynamics Experiment (CODE) (Allen et al, 1982) by the principal investigators of the bottom stress/bottom boundary layer component of CODE (D. Cacchione, D. Drake, USGS; and W. Grant, A. Williams, WHOI) and other cooperating investigators of the U.S. Geological Survey.
    Description: Funding was provided by the National Science Foundation under Grant OCE 80-14938 and OCE 80-14941 and by the United States Geological Survey.
    Keywords: Coastal Ocean Dynamics Experiment (CODE) ; Ocean waves ; Ocean-atmosphere interaction ; Ocean bottom
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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    Sea duct : a deep-sea computer-controlled recirculating flume for the study of sea floor stability : final report (2015)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: The Sea Duct Ocean-Bottom Laboratory is a computer controlled recirculating inverted flume for the in-situ study of sediment transport. It is designed to measure the sea floor response to controlled currents analogous to those generated by surface waves, tidal, or deep ocean storms. The external support frame is an equilateral triangle with sixteen foot sides. It is 12 feet high, has an air weight of 12,500 lbs., and a 2800 lb. submerged weight. Three lead acid battery packs located at the vertex of the triangle legs provide power for the recirculating water pumps, hydraulic power, and ancillary equipment. The inner rotatable structure consists of a 4 foot long by 2 foot wide open bottom windowed test section that is 9 inches high. It is connected to 30 feet of 8 inch tube configured as an elongated toroid. Above the test section is a traverse carriage with stereo camera, flash, and a laser Doppler velocimeter to measure fluid stresses. Internal flow velocities are controlled and can be ramped up to approximately 2 ft/sec providing shear stress sufficient to scour sand, silts, and fine clays. Water and sediment sampling devices obtain specimens from inside and outside the test section. This report consists of three sections. The first subdivision discusses the electro-mechanical systems and deployment- recovery techniques, while the second portion covers the microprocessor controller and its support equipment. The third section contains the appendices, which consists of program listings, schematics, system and deployment check-list, etc.
    Description: Office of Naval Research, Environmental Sciences Directorate, under Contracts N00014-85-C-0001 and N00014-87-K-007
    Keywords: Marine sediments ; Sediment transport ; Ocean bottom ; Ocean currents ; Data processing
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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    Particle fluxes, south central Black Sea : 1982-1985 (2015)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: Black Sea Sedimentation data file, V. 1
    Description: Annual particle fluxes were measured by sediment traps deployed at a station about 40 km north of Amasra, Southern Black Sea, by an international team of oceanographers from Germany, Turkey, and the United States. This experiment continuously monitored oceanic particle flux for two and a half years from October 28, 1982 to April 6, 1985 at approximately two-week intervals at 250 m and 1200 m below the surface using 1.2 m2 Mark 5-12 time-series sediment traps. The water depth at this station was about 2,200 m and both traps were situated within the anoxic layer of the Black Sea. The collected flux samples were analyzed at the Woods Hole Oceanographic Institution to document the basic sedimentary characteristics using a quarter of each sample split. In the first data file from this experiment, total mass, carbonate, noncombustible, combustible, opal (biogenic silica), organic carbon, and organic nitrogen fluxes data are presented in bar graphs and detailed tables, in unit samples covering a two-week period at each depth. The Black Sea Sedimentation Data File is intended to provide source data on particle fluxes from this unique ocean environment for further investigation and for planning advanced research programs.
    Description: Funding for the field program was provided by: Forderkennzeichen KF 1001./2, BMFT National Science Foundation OCE82-8736 (partial) Turkish Research Council Funding for laboratory analysis was supported by National Science Foundation OCE86-017106
    Keywords: Koca Piri Reis (Ship) Cruise ; Sedimentation and deposition ; Sediment transport
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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  • 45
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    Technical summary of USGS OBS operation R/V JOIDES Resoultion, ODP leg 179 (2016)
    Woods Hole Oceanographic Institution
    Details
    Publication Date: 2022-05-26
    Description: The experiment was to determine if a technique known as "Seismics While Drilling" was a viable means of gathering seismic images of near hole structure without consuming any rig time. The idea is to use a correlation technique between the drill bit vibrations and seismometers installed at the seafloor much like an inverted Vertical Seismic Profile (VSP). LDEO Borehole Group constructed and operated the pilot sensor consisting of a three axis accelerometer and mounted on the drill string. USGS OBS were deployed on the ocean floor within a few hundred meters of the drill hole. At the first site, (deploy! Hole 1104E) a hammer drill bit was recorded as a sort of warmup drop and out of curiosity as to how this might compare to the other drilling which used a roller cone coring bit and a regular tri-cone bit. This was a short session lasting less than 24 hours. The next deployment, deploy2 Hole II OSA, was during a coring operation that lasted seven days with core to depth of 154m with no sediments. During this period the pilot sensor operated for 2.5 days. The final deployment, deploy3 Hole 1107A, was during the drilling of 370m of sediment and 114m of basement below the sediment. The pilot sensor operated during 36 hours of the drilling, through the sediments and 45 meters into basement. In addition to the drilling recordings, a few tests were performed to assist the processing phase. First a dockside test with all three sensors located side by side on the dock in Cape Town was recorded, deploy 0 called dock or dockside . This data was shipped back before sailing to prime the data format conversion process. Two OBS diagnostic tests were recorded aboard the ship to test noise levels of amplifier electronics, Preamp I and Preamp2. Finally, a sine wave generator was connected to an OBS and the pilot sensor recorder at the same time in order to ensure time labelling consistency and provide an easy signal to compare against for data conversion methods, called sinesync. A few lines of refraction shooting by the F/S Sonne were also recorded during deploy3 at Hole 1107A. These were part of the SINUS project which was supposed to include recording of a borehole seismometer at the bottom of the hole. The JOIDES Resolution ran out of time and was unable to complete this portion of the experiment. LDEO Borehole announced at the outset of the cruise they would withhold all pilot sensor data and deliver it after the cruise. Thus no shipboard correlation was possible. It is unlikely operations could have been altered much in any case.
    Description: This material is based upon work supported by the National Science Foundation (NSF Grant Number OCE - 9730588).
    Keywords: Boring ; Ocean bottom ; JOIDES Resolution (Ship)
    Repository Name: Woods Hole Open Access Server
    Type: Working Paper
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