Trivett D. Andrew

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D. Andrew

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  • Article
    Predicted scattering of sound by diffuse hydrothermal vent plumes at mid-ocean ridges
    (Acoustical Society of America, 1998-01) Duda, Timothy F. ; Trivett, D. Andrew
    Amplitude and phase fluctuations of monochromatic acoustic signals traveling through diffuse mid-ocean ridge hydrothermal vent plumes are modeled using existing theory in an attempt to find suitable frequencies and path lengths for plume monitoring. Weak-scattering solutions are evaluated numerically, with model parameters adjusted to match observed plume characteristics. Constraints required for weak-scattering solutions to be valid can be met for transmission ranges of 500–2000 m and frequencies of 20–80 kHz. Therefore, because fluid structure and scattering strength are more closely linked for weak scattering than for stronger scattering, inversion for fluid statistical properties may be possible, enabling diffuse vent monitoring. Such monitoring would be subject to geometric assumptions such as transmission entirely within a statistically homogeneous plume. Performance-limiting phase fluctuations have also been computed for a 13–17 kHz geodetic survey system.
  • Thesis
    Diffuse flow from hydrothermal vents
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1991-06) Trivett, D. Andrew
    The effluent from a collection of diffuse hydrothennal vents was modelled to determine the fate of this source of flow under typical environmental conditions at seafloor spreading centers. A laboratory simulation was conducted to test an analytic model of diffuse plume rise. The results showed that diffuse plumes are likely to remain near the seafloor, with their maximum rise height scaled with the diameter of the source of diffuse flow. The entrainment of ambient seawater into these plumes is limited by the proximity to the seafloor, thus slowing the rate of dilution. The model of diffuse plume behaviour was used to guide the design and implementation of a scheme for monitoring the flow from diffuse hydrothermal vents in the ocean. A deployment of an array at the Southern Juan de Fuca Ridge yielded measurements of a variety of diffuse plume properties, including total heat output. Two distinct sources of hydrothermal flow were detected during the field deployment. The larger source was 1-1 .5km north of the instrument array. and its energy output was 450±270MW. A smaller source was located 100m east of one instrument in the array. The energy output of this source was 12±8MW. The rise heights of the centerlines of these plumes were 45m and 10m, respectively.