Gobat Jason I.

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Gobat
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Jason I.
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  • Technical Report
    Long-term evolution of the coupled boundary layers (STRATUS) mooring recovery and deployment cruise report NOAA Research Vessel R H Brown • cruise RB-01-08 9 October - 25 October 2001
    (Woods Hole Oceanographic Institution, 2002-02) Vallee, Charlotte ; Weller, Robert A. ; Bouchard, Paul R. ; Ostrom, William M. ; Lord, Jeffrey ; Gobat, Jason I. ; Pritchard, Mark ; Westberry, Toby K. ; Hare, Jeffrey E. ; Uttal, Taneil ; Yuter, Sandra ; Rivas, David ; Baumgardner, Darrel ; McCarty, Brandi ; Shannahoff, Jonathan ; Walsh, M. Alexander ; Bahr, Frank B.
    This report documents the work done on cruise RB-01-08 of the NOAA R/V Ron Brown. This was Leg 2 of R/V Ron Brown’s participation in Eastern Pacific Investigation of Climate (EPIC) 2001, a study of air-sea interaction, the atmosphere, and the upper ocean in the eastern tropical Pacific. The science party included groups from the Woods Hole Oceanographic Institution (WHOI), NOAA Environmental Technology Laboratory (ETL), the University of Washington (UW), the University of California, Santa Barbara (UCSB), and the University Nacional Autonoma de Mexico (UNAM). The work done by these groups is summarized in this report. In addition, the routine underway data collected while aboard R/V Ron Brown is also summarized here.
  • Technical Report
    The horizontal mooring : a two-dimensional array, description of the array, components, instrumentation, deployment and recovery operations
    (Woods Hole Oceanographic Institution, 1999-09) Trask, Richard P. ; Anderson, Steven P. ; Way, Bryan S. ; Ostrom, William M. ; Paul, Walter ; Grosenbaugh, Mark A. ; Gobat, Jason I. ; Weller, Robert A.
    A moored two-dimensional array with instrumentation distributed both horizontally and vertically was deployed for 27 days in August 1998 at an 85 meter deep site in Massachusetts Bay near Stellwagon basin. The horizontal mooring consisted of a 160- meter long horizontal element positioned at a depth of 20 meters between two subsurface moorings. Suspended below the horizontal member were five 25-meter long vertical strings. The vertical strings had a horizontal separation of 30 meters and each had instruments at depths of 20, 25, 30, 35, 40 and 45 meters. Instrumentation deployed on the two-dimensional array included acoustic current meters, temperature sensors, conductivity measuring instruments, pressure sensors and motion monitoring packages. This report includes a detailed description of the two-dimensional array, the anchoring system and the instrumentation that were deployed. Also included is a description of the deployment and recovery techniques that were employed as well as an assessment of the performance of the array.
  • Technical Report
    A compact coastal ocean observing system for Kernel Blitz 2001
    (Woods Hole Oceanographic Institution, 2001-12) Gobat, Jason I. ; Weller, Robert A. ; Way, Bryan S. ; Lord, Jeffrey ; Pritchard, Mark ; Smith, Jason C.
    In this report we describe a compact, easily deployed, moored system for oceanographic and meteorological observations in the coastal ocean. The system consists of a surface and subsurface mooring pair deployed adjacent to one another. Compared to a single catenary surface mooring, this arrangement allows the entire water column to be instrumented. All of the instruments in the system log high resolution time series data. Additionally, the mooring line instruments periodically report averaged data to the buoys via inductive modems. On the subsurface mooring, this averaged data is sent to the surface buoy using an acoustic modem. Inductively coupled mooring line instrumentation includes conductivity, temperature, and pressure sensors, acoustic current meters, and optical backscattering and absorption sensors. In addition to mooring line instruments, the surface buoy collects averaged data from meteorological sensors, including wind speed and direction, barometric pressure, relative humidity, air temperature, precipitation, longwave and shortwave radiation, sea surface temperature and conductivity, and wave height and period. Data from both mooring lines and from the surface meteorological sensors is telemetered to shore via line-of-sight radio and satellite. The entire system, including buoys, moorings, instruments, launch and recovery gear, telemetry receive, and data processing facilities can be packed into a single 20 foot shipping container. The system was successfully deployed to provide environmental monitoring for Kernel Blitz 2001, a US Navy fleet exercise off southern California. Results from the deployment are presented.
  • Technical Report
    CBLAST-Low 2001 pilot study mooring deployment cruise and data report ; FV Nobska, June 4 to August 17, 2001
    (Woods Hole Oceanographic Institution, 2002-05) Pritchard, Mark ; Gobat, Jason I. ; Ostrom, William M. ; Lord, Jeffrey ; Bouchard, Paul R.
    During the summer of 2001, several moorings and cruises were used as part of the CBLAST-Low (Coupled Boundary Layer Air-Sea Transfer under low wind conditions) pilot experiment in the North Atlantic, south of Martha’s Vineyard Island, MA, USA. Six subsurface tide gauges were deployed around the study site for a period of approximately 3 months during the summer of 2001. Further, two surface buoys equipped with meteorological instrumentation and subsurface arrays that measured temperature, conductivity and velocity were deployed during the months of July and August 2001. For a short intensive operating period during July 2001, a newly manufactured three-dimensional mooring designed to sample three-dimensional properties of the upper ocean was deployed for a period of 6 days. During the Intensive Operating Period (IOP) along-shelf and across-shelf conductivity-temperature-depth (CTD) sections were completed as well as a drifting array designed to passively collect data from the upper water column released for approximately 24 hours. This report describes the instrumentation and type of moorings deployed by the Woods Hole Oceanographic Institution Upper Ocean Processes (WHOI UOP) group as well as data return and quality from the CBLAST-Low 2001 pilot study. This is summarized in graphical and tabular form in this report.
  • Technical Report
    WHOI cable : time domain numerical simulation of moored and towed oceanographic systems
    (Woods Hole Oceanographic Institution, 1997-11) Gobat, Jason I. ; Grosenbaugh, Mark A. ; Triantafyllou, Michael S.
    This report presents a numerical framework for analyzing the statics and dynamics of cable strctures commonly encountered in oceanographic engineering practice. The numerical program, WHOI Cable, features a nonlinear solver that includes the effects of geometric and material nonlinearties, bending stiffness for seamless modeling of slack cables, and a model for the interaction of cable segments with the seafoor. The program solves both surface and subsurface single-point mooring problems, systems with both ends anchored on the bottom, and towing and drifter problems. Forcing includes waves, current, ship speed, and pay-out of cable. The programs that make-up WHOI Cable run under Unix, DOS, and Windows. There is a familiar Windows-style interface available for Windows 95 and Windows NT platforms. In the report, the mathematical and numerical framework for WHOI Cable is described, followed by detailed instructions for formulating problem input files and running the codes. Examples are included in an appendix to highlight the range of problems that WHOI Cable can solve.
  • Technical Report
    WHOI Cable v2.0 : time domain numerical simulation of moored and towed oceanographic systems
    (Woods Hole Oceanographic Institution, 2000-07) Gobat, Jason I. ; Grosenbaugh, Mark A.
    This report describes version 2.0 of a numerical program for analyzing the statics and dynamics of cable structures commonly encountered in oceanographic engineering practice. The numerical program, WHOI Cable, features a nonlinear solver that includes the effects of geometric and material nonlinearities, bending stiffness for seamless modeling of slack cables, and a model for the interaction of cable segments with the seafloor. The program solves both surface and subsurface single- and multi-point mooring problems, systems with both ends anchored on the bottom, and towing and drifter problems. Forcing includes waves, current, wind, ship speed, and pay-out of cable. The programs that make-up WHOI Cable run under Unix and Windows. There is familiar graphical interface available for Windows platforms. The report includes detailed instructions for formulating problem input files and running the programs.
  • Thesis
    The dynamics of geometrically compliant mooring systems
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2000-06) Gobat, Jason I.
    Geometrically compliant mooring systems that change their shape to accommodate deformations are common in oceanographic and offshore energy production applications. Because of the inherent geometric nonlinearities, analyses of such systems typically require the use of a sophisticated numerical model. This thesis describes one such model and uses that model along with experimental results to develop simpler forms for understanding the dynamic response of geometrically compliant moorings. The numerical program combines the box method spatial discretization with the generalized- a method for temporal integration. Compared to other schemes commonly employed for the temporal integration of the cable dynamics equations, including box method, trapezoidal rule, backward differences, and Newmark’s method, the generalized-a algorithm has the advantages of second-order accuracy, controllable numerical dissipation, and improved stability when applied to the nonlinear problem. The numerical program is validated using results from laboratory and field experiments. Field experiment and numerical results are used to develop a simple model for dynamic tension response to vertical motion in geometrically compliant moorings. As part of that development, the role of inertia, drag, and stiffness in the tension response are explored. For most moorings, the response is dominated by inertial and drag effects. The simple model uses just two terms to accurately capture these effects, including the coupling between inertia and drag. The separability of the responses to vertical and horizontal motions is demonstrated and a preliminary model for the response to horizontal motions is presented. The interaction of the mooring line with the sea floor in catenary moorings is considered. Using video and tension data from laboratory experiments, the tension shock condition at the touchdown point and its implications are observed for the first time. The lateral motion of line along the bottom associated with a shock during unloading may be a significant cause of chain wear in the touchdown region. Results from the laboratory experiments are also used to demonstrate the suitability of the elastic foundation approach to modeling sea floor interaction in numerical programs.