Donoghue Terence

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Donoghue
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Terence
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  • Other
    Brazil Basin Tracer Release Experiment
    (Woods Hole Oceanographic Institution, 2021-04) Ledwell, James R. ; Donoghue, Terence ; Guest, Brian J. ; Lemmond, Peter ; Sellers, Cynthia J. ; Cortes, Norbert
    The purpose of the Brazil Basin Tracer Release Experiment is to measure diapycnal (across isopycnal) mixing and epipycnal (along-isopycnal) mixing and stirring in the deep ocean. This cruise is the fourth in the overall experiment. In the first cruise in early 1996, 110 kg of sulfur hexafluoride (SF6) were released on an isopycnal surface near 4000 meters depth in the eastern part of the basin on the flanks of the Mid-Atlantic Ridge (MAR). The location of the release was near 21.7 S, 18.4 W. The release site was over a zonal valley that leads to the MAR and is about 5000 m deep. The isopycnal surface of the release was defined as the surface on which the potential density anomaly, referenced to 4000 dbar pressure, was 45.9408 kg/m3. The release streaks and results of initial sampling in 1996 are described in Polzin et al. [1997].
  • 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.