HR: 11:50h
AN: OS42A-07    [Abstracts]
TI: Mapping hydrothermal plumes in their rising and neutrally buoyant regimes with an autonomous underwater vehicle
AU: * Jakuba, M
EM: jakuba@mit.edu
AF: Woods Hole Oceanographic Institution, Deep Submergence Lab MS #7, Woods Hole, MA 02543 United States
AU: Yoerger, D
EM: dyoerger@whoi.edu
AF: Woods Hole Oceanographic Institution, Deep Submergence Lab MS #7, Woods Hole, MA 02543 United States
AU: Stahr, F
AF: University of Washington, School of Oceanography Box 357940, Seattle, WA 98195-7940 United States
AU: McDuff, R
AF: University of Washington, School of Oceanography Box 357940, Seattle, WA 98195-7940 United States
AB: Propeller-driven autonomous underwater vehicles (AUVs) potentially enable unique perspectives on hydrothermal plumes that address both the temporal and spatial variability inherent in these structures. Like a lowered or profiling CTD, an AUV offers a platform capable of collecting multiple coregistered data; however, precise navigation and control of an AUV enables complex survey patterns and makes available the possibility of altering vehicle trajectory in real-time. We present data collected by the Autonomous Benthic Explorer (ABE) in June/July 2004 in both the buoyant and neutral components of hydrothermal plumes above the Main Endeavour Field, Juan de Fuca Ridge. The ABE recorded coregistered optical backscatter, temperature and conductivity from two vertically separated probe pairs, redox potential (eH), and water column current velocity from a doppler velocity log (DVL). Bottom-referenced vehicle velocity from the DVL and long baseline positioning enabled the water column velocities from the DVL to be accurately referenced to a stationary world frame. Despite the fact that background currents vary considerably over the course of a single AUV survey due to tidal effects, the use of water column velocity DVL data permits the recovery of better approximations to the time-varying structure of the tracer field in the plume. Using data from above the Juan de Fuca Ridge, we present several candidate triggers that could initiate autonomous behavior to increase survey resolution locally, for instance to improve the possibility of unabiguous detection of rising plume stems from within the neutrally buoyant plume. The envisioned adaptive strategy would result in precisely oriented fine-scale grids within the wider-spaced pre-defined survey. Such a strategy could provide an improvement in spatial resolution in critical regions of the plume without sacrificing the large-scale temporal resolution of the plume.
DE: 3035 Midocean ridge processes
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting