Doherty Kenneth W.

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Doherty
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Kenneth W.
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  • Technical Report
    Design and operation of automated ice-tethered profilers for real-time seawater observations in the polar oceans
    (Woods Hole Oceanographic Institution, 2006-06) Krishfield, Richard A. ; Doherty, Kenneth W. ; Frye, Daniel E. ; Hammar, Terence R. ; Kemp, John N. ; Peters, Donald B. ; Proshutinsky, Andrey ; Toole, John M. ; von der Heydt, Keith
    An automated, easily-deployed Ice-Tethered Profiler (ITP) has been developed for deployment on perennial sea ice in polar oceans to measure changes in upper ocean temperature and salinity in all seasons. The ITP system consists of three components: a surface instrument that sits atop an ice floe, a weighted, plastic-jacketed wire-rope tether of arbitrary length (up to 800 m) suspended from the surface instrument, and an instrumented underwater unit that profiles up and down the wire tether. The profiling underwater unit is similar in shape and dimension to an ARGO float except that the float's variable-buoyancy system is replaced with a traction drive unit. Deployment of ITPs may be conducted either from ice caps or icebreakers, utilizing a self contained tripod/winch system that requires no power. Careful selection of an appropriate multiyear ice floe is needed to prolong the lifetime of the system (up to 3 years depending on the profiling schedule). Shortly after deployment, each ITP begins profiling the water column at its programmed sampling interval. After each acquired temperature and salinity profile, the underwater unit (PROCON) transfers the data and engineering files using an inductive modem to the surface controller (SURFCON). SURFCON also accumulates battery voltages, buoy temperature, and locations from GPS at specified intervals in status files, and queues that information for transmission at the start of each new day. At frequent intervals, an Iridium satellite transceiver in the surface package calls and transmits queued status and CTD data files onto a WHOI logger computer, which are subsequently processed and displayed in near-real time at http://www.whoi.edu/itp. In 2004 and 2005, three ITP prototypes were deployed in the Arctic Ocean. Each system was programmed with accelerated sampling schedules of multiple one-way traverses per day between 10 and 750-760 m depth in order to quickly evaluate endurance and component fatigue. Two of the ITPs are continuing to function after more than 10 months and 1200 profiles. Larger motor currents are observed at times of fast ice floe motion when larger wire angles develop and drag forces on the profiler are increased. The CTD profile data so far obtained document interesting spatial variations in the major water masses of the Beaufort Gyre, show the double-diffusive thermohaline staircase that lies above the warm, salty Atlantic layer, and many mesoscale eddys. Deployed together with CRREL Ice Mass Balance (IMB) buoys, these ITP systems also operate as part of an Ice Based Observatory (IBO). Data returned from an array of IBOs within an Arctic Observing Network will provide valuable real time observations, support studies of ocean processes, and facilitate numerical model initialization and validation.
  • Technical Report
    Ice-Ocean Environmental Buoys (IOEB) : technology and deployment in 1991-1992
    (Woods Hole Oceanographic Institution, 1993-10) Krishfield, Richard A. ; Doherty, Kenneth W. ; Honjo, Susumu
    Based upon the 1987-88 Arctic Environmental Drifting Buoy (AEDB), the Ice-Ocean Environmental Buoy (IOEB) was developed to acquire and telemeter in near real-time inter-relatable time-series data on atmospheric, oceanographic and ice physics in ice-covered oceans during all seasons. Two IOEBs were successfully deployed in two Arctic Sea Basin Stations in April, 1992. Since then, although some sensors malfunctioned, for 18 continuous months, they have been sending massive amounts of information. In this report we describe the technology which was developed for the 1991 IOEB. Mechanically, the IOEB consists of an extremely durable surface flotation package and an underwater mooring line of instruments and sensors. The apex contains data loggers for air, ice and engineering measurements, microcontroller modules for accumulating the data from all the instruments, and ARGOS platform transmit terminals (PTTs) for broadcasting the data. Extending above the surface float, a mast supports a wind monitor and air temperature probe, which along with a barometer provides meteorological data. Thermistor strings, vibrating wire stress sensors, and a thickness gauge are installed in the ice surrounding the buoy, and are interrogated by the modules inside the apex. In the ocean, 110m of conducting strength cable passes the data from conductivity/temperature recorders, an Acoustic Doppler Current Profier and data compression module, a dissolved oxygen sensor, a transmissometer and fluorometers to the PTT microcontrollers. Furthermore, a suspended particle collector and sediment trap transmit status information along the two-wire multidrop network cable. Because the IOEB differs from the AEDB by telemetering the majority of the scientific data, a complicated compression scheme is incorporated to broadcast the data from the 103 variables within the allowable 256-bit ARGOS data stream. Via Service ARGOS, this data currently becomes available to scientists in several countries within eight hours of transmission. In April 1992, two IOEBs were deployed at separate ice camps in the Arctic Ocean with battery power adequate to sustain the systems for over two years. One was deployed 115 miles from the North Pole in the center of the Transpolar Drift sea-ice current, and the other off of the coast of Alaska along the edge of the Beaufort Gyre. Airplanes capable of landing on ice were used for the transportation of the systems to their final destination. Simultaneously, a third, reduced version of the IOEB was deployed in the Weddell Sea by the Scott Polar Research Institute.
  • Preprint
    Autonomous Microbial Sampler (AMS), a device for the uncontaminated collection of multiple microbial samples from submarine hydrothermal vents and other aquatic environments
    ( 2006-01-11) Taylor, Craig D. ; Doherty, Kenneth W. ; Molyneaux, Stephen J. ; Morrison, Archie T. ; Billings, John D. ; Engstrom, Ivory B. ; Pfitsch, Don W. ; Honjo, Susumu
    An Autonomous Microbial Sampler (AMS) is described that will obtain uncontaminated and exogenous DNA-free microbial samples from most marine, fresh water and hydrothermal ecosystems. Sampling with the AMS may be conducted using manned submersibles, Remotely Operated Vehicles (ROVs), Autonomous Underwater Vehicles (AUVs), or when tethered to a hydrowire during hydrocast operations on research vessels. The modular device consists of a titanium nozzle for sampling in potentially hot environments (>350°C) and fluid-handling components for the collection of six independent filtered or unfiltered samples. An onboard microcomputer permits sampling to be controlled by the investigator, by external devices (e.g., AUV computer), or by internal programming. Temperature, volume pumped and other parameters are recorded during sampling. Complete protection of samples from microbial contamination was observed in tests simulating deployment of the AMS in coastal seawater, where the sampling nozzle was exposed to seawater containing 1x106 cells ml-1 of a red pigmented tracer organism, Serratia marinorubra. Field testing of the AMS at a hydrothermal vent field was successfully undertaken in 2000. Results of DNA destruction studies have revealed that exposure of samples of the Eukaryote Euglena and the bacterium S. marinorubra to 0.5 N sulfuric acid at 23°C for 1 hour was sufficient to remove Polymerase Chain Reaction (PCR) amplifiable DNA. Studies assessing the suitability of hydrogen peroxide as a sterilizing and DNA-destroying agent showed that 20 or 30% hydrogen peroxide sterilized samples of Serratia in 1 hr and destroyed the DNA of Serratia, in 3 hrs, but not 1 or 2 hrs. DNA AWAY™ killed Serratia and destroyed the DNA of both Serratia and the vent microbe (GB-D) of the genus Pyrococcus in 1 hour.
  • Technical Report
    Water samplers for open ocean tracer release experiments
    (Woods Hole Oceanographic Institution, 1998-12) Donoghue, Terence ; Ledwell, James R. ; Doherty, Kenneth W.
    Conventional "spot" sampling of patchy distributions of oceanic constituents can lead to sampling errors. Interpretation of results based on data of disparate temporal or spatial resolution can be difficult or impossible. Ths report discusses the design and performance of two water sampling devices which attempt to minimize these problems. The devices were created for open ocean tracer release experiments, but can be used for other experiments where inhomogeneity is anticipated. The first sampler is a mechancally-operated, variable-rate integrating water sampler which acquires a time-averaged sample. The sampler incorporates featues of both the spring-driven and the hydraulically-driven samplers described by Ledwell et al., 1991. The second sampler is a multichamber sampling system incorporating a battery powered pump and valve system made by McLane Research, Inc., of Falmouth, Massachusett. The system consists of a micro-gear pump, a 50-port valve with programmable controller, and carousels contaning fifty glass sampling syringes. It can be programmed to sample on a variety of schedules allowing the user flexibilty in the field to adapt to changing requirements. A general description, operational instructions, and performance analysis are provided for each sampler system.
  • Technical Report
    Design and evaluation of a directional antenna for ocean buoys
    (Woods Hole Oceanographic Institution, 1997-11) Frye, Daniel E. ; Doherty, Kenneth W. ; Hinton, Al
    A system concept has been developed by Viasat, Inc. and Woods Hole Oceanographic Institution for improving the data telemetry bandwidth available on ocean buoys. This concept utilizes existing communications satellites as data relay stations and mechanically steered antenna arrays to achieve increased data rates and improved power efficiency needed for ocean applications. This report describes an initial feasibility and design study to determine if a mechanically steered antenna array can meet the requirements of open ocean buoy applications. To meet the system requirements, an 18-element microstrip antenna (9-element transmit, 9-element receive) was designed and fabricated under subcontract by Seavey Engineering Associates, Inc. It operates in the 4-6GHz frequency band (C-band) and provides 14 dB of gain. The 1/2 power beamwidth is +-t5° in azimuth and elevation. This antenna design, in conjunction with a simple rotating mount, was used to evaluate the potential of this approach to keep a geostationary satellite in view when mounted on an ocean buoy. The evaluation is based on laboratory measurements using a magnetic compass and a small stepper motor to maintain antenna orientation while the complete assembly was rotated and tilted at speeds similar to what would be expected on an offshore buoy equipped with a stabilizing wind vane. The results are promising, but less than conclusive because of limitations in the experimental test setup. The recent introduction of several commercially available mechanically steered antennas designed for use on small boats may provide a viable alternative to the approach described here with appropriate modification to operate at C-band.
  • Working Paper
    DSRV Alvin weight report, 1973
    (Woods Hole Oceanographic Institution, 1973-12) Sharp, Arnold G. ; Doherty, Kenneth W.
    Weight and stability computations are presented for the research submarine ALVIN following the installation, early in 1973, of the new titanium alloy pressure hull built by the U.S. navy under "Project Titanes." Longitudinal and vertical components of the BG distance are shown for the vehicle in its normal submerged condition, and for a number of emergency conditions. Calculations for pounds per inch immersion and moment to heel one degree also are included. results of the post-refit dockside trials are presented and discussed.