Vernon Frank L.

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Vernon
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Frank L.
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  • Working Paper
    Broadband borehole seismic system integration tests : report of the system integration tests at MPL/SIO
    (Woods Hole Oceanographic Institution, 1998) Goldsborough, Robert G. ; Austin, Gary ; Bolmer, S. Thompson ; Jabson, David M. ; Jonke, Patrick ; Gould, Matthew R. ; Hildebrand, John A. ; Hollinshead, C. B. ; Offield, Glen ; Orcutt, John ; Peal, Kenneth R. ; Spiess, Fred N. ; Stephen, Ralph A. ; Vernon, Frank L. ; Willoughby, David F. ; Zimmerman, Richard
    This report describes a series of tests performed at SIO/MPL, Point Lorna the week of 17 November 1997 designed to achieve integration of the Broadband Borehole Seismic System (BBBSS) in preparation for the OSN Pilot Experiment cruise on RN Thompson during January 1997. Representatives from all groups were present (see appendix A), with their respective parts of the system and support equipment. It was anticipated that these tests would result in the complete integration of the various components of the borehole seismometer system in preparation for the January cruise. The system would be assembled and tested following a plan (see appendix C) that would culminate in the fully integrated borehole seismometer being wet tested off the MPL pier.
  • Article
    Multipurpose acoustic networks in the integrated Arctic Ocean observing system
    (Arctic Institute of North America, 2015) Mikhalevsky, Peter N. ; Sagen, Hanne ; Worcester, Peter F. ; Baggeroer, Arthur B. ; Orcutt, John A. ; Moore, Sue E. ; Lee, Craig M. ; Vigness-Raposa, Kathleen J. ; Freitag, Lee E. ; Arrott, Matthew ; Atakan, Kuvvet ; Beszczynska-Möller, Agnieszka ; Duda, Timothy F. ; Dushaw, Brian D. ; Gascard, Jean-Claude ; Gavrilov, Alexander N. ; Keers, Henk ; Morozov, Andrey K. ; Munk, Walter H. ; Rixen, Michel ; Sandven, Stein ; Skarsoulis, Emmanuel ; Stafford, Kathleen M. ; Vernon, Frank L. ; Yuen, Mo Yan
    The dramatic reduction of sea ice in the Arctic Ocean will increase human activities in the coming years. This activity will be driven by increased demand for energy and the marine resources of an Arctic Ocean accessible to ships. Oil and gas exploration, fisheries, mineral extraction, marine transportation, research and development, tourism, and search and rescue will increase the pressure on the vulnerable Arctic environment. Technologies that allow synoptic in situ observations year-round are needed to monitor and forecast changes in the Arctic atmosphere-ice-ocean system at daily, seasonal, annual, and decadal scales. These data can inform and enable both sustainable development and enforcement of international Arctic agreements and treaties, while protecting this critical environment. In this paper, we discuss multipurpose acoustic networks, including subsea cable components, in the Arctic. These networks provide communication, power, underwater and under-ice navigation, passive monitoring of ambient sound (ice, seismic, biologic, and anthropogenic), and acoustic remote sensing (tomography and thermometry), supporting and complementing data collection from platforms, moorings, and vehicles. We support the development and implementation of regional to basin-wide acoustic networks as an integral component of a multidisciplinary in situ Arctic Ocean observatory.
  • Working Paper
    Tests of the broadband borehole seismic system (B³S²) at Scripps IGPP and the Pinon Flat Observatory : October 1994 to June 1995
    (Woods Hole Oceanographic Institution, 1997-08) Stephen, Ralph A. ; Orcutt, John ; Peal, Kenneth R. ; Vernon, Frank L. ; Austin, Gary ; Bolmer, S. Thompson ; Gould, Matthew R. ; Koelsch, Donald E. ; Hollinshead, C. B. ; Offield, Glen ; Willoughby, David F.
    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.
  • Article
    Ocean Seismic Network Pilot Experiment
    ( 2003-10-31) Stephen, Ralph A. ; Spiess, Fred N. ; Collins, John A. ; Hildebrand, John A. ; Orcutt, John A. ; Peal, Kenneth R. ; Vernon, Frank L. ; Wooding, Frank B.
    The primary goal of the Ocean Seismic Network Pilot Experiment (OSNPE) was to learn how to make high quality broadband seismic measurements on the ocean bottom in preparation for a permanent ocean seismic network. The experiment also had implications for the development of a capability for temporary (e.g., 1 year duration) seismic experiments on the ocean floor. Equipment for installing, operating and monitoring borehole observatories in the deep sea was also tested including a lead-in package, a logging probe, a wire line packer and a control vehicle. The control vehicle was used in three modes during the experiment: for observation of seafloor features and equipment, for equipment launch and recovery, and for power supply and telemetry between ocean bottom units and the ship. The OSNPE which was completed in June 1998 acquired almost four months of continuous data and it demonstrated clearly that a combination of shallow buried and borehole broadband sensors could provide comparable quality data to broadband seismic installations on islands and continents. Burial in soft mud appears to be adequate at frequencies below the microseism peak. Although the borehole sensor was subject to installation noise at low frequencies (0.6 to 50 mHz), analysis of the OSNPE data provides new insights into our understanding of ocean bottom ambient noise. The OSNPE results clearly demonstrate the importance of sediment borne shear modes in ocean bottom ambient noise behavior. Ambient noise drops significantly at high frequencies for a sensor placed just at the sediment basalt interface. At frequencies above the microseism peak, there are two reasons that ocean bottom stations have been generally regarded as noisier than island or land stations: ocean bottom stations are closer to the noise source (the surface gravity waves) and most ocean bottom stations to date have been installed on low rigidity sediments where they are subject to the effects of shear wave resonances. When sensors are placed in boreholes in basement the performance of ocean bottom seismic stations approaches that of continental and island stations. A broadband borehole seismic station should be included in any real-time ocean bottom observatory.
  • Working Paper
    Progress report on the development of the seafloor borehole array seismic system (phase II) : July 14, 1992 to January 31, 1996
    (Woods Hole Oceanographic Institution, 1996-06) Stephen, Ralph A. ; Peal, Kenneth R. ; Bolmer, S. Thompson ; Gould, Matthew R. ; Koelsch, Donald E. ; Orcutt, John A. ; Vernon, Frank L. ; Offield, G. ; Willoughby, David F. ; Hollinshead, C. B. ; Spiess, Fred N. ; Hildebrand, John A. ; Zimmerman, Richard ; Austin, Gary
    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.
  • Article
    Field measurements of sonic boom penetration into the ocean
    (Acoustical Society of America, 2000-06) Sohn, Robert A. ; Vernon, Frank L. ; Hildebrand, John A. ; Webb, Spahr C.
    Six sonic booms, generated by F-4 aircraft under steady flight at a range of altitudes (610–6100 m) and Mach numbers (1.07–1.26), were measured just above the air/sea interface, and at five depths in the water column. The measurements were made with a vertical hydrophone array suspended from a small spar buoy at the sea surface, and telemetered to a nearby research vessel. The sonic boom pressure amplitude decays exponentially with depth, and the signal fades into the ambient noise field by 30–50 m, depending on the strength of the boom at the sea surface. Low-frequency components of the boom waveform penetrate significantly deeper than high frequencies. Frequencies greater than 20 Hz are difficult to observe at depths greater than about 10 m. Underwater sonic boom pressure measurements exhibit excellent agreement with predictions from analytical theory, despite the assumption of a flat air/sea interface. Significant scattering of the sonic boom signal by the rough ocean surface is not detected. Real ocean conditions appear to exert a negligible effect on the penetration of sonic booms into the ocean unless steady vehicle speeds exceed Mach 3, when the boom incidence angle is sufficient to cause scattering on realistic open ocean surfaces.