HR: 0800h
AN: T31A-0490    [Abstracts]
TI: Repeat Hydrography at the Endeavour Integrated Study Site, 2004 - 2005
AU: * Kellogg, J P
EM: kellogj@u.washington.edu
AF: University of Washington, School of Oceanography Box 357940, Seattle, WA 98195-7940 United States
AU: McDuff, R E
EM: mcduff@ocean.washington.edu
AF: University of Washington, School of Oceanography Box 357940, Seattle, WA 98195-7940 United States
AU: Thomson, R E
EM: thomsonr@pac.dfo-mpo.gc.ca
AF: Institute of Ocean Sciences, Department of Fisheries and Oceans Box 6000, Sidney, BC V8L 4B2 Canada
AU: Stahr, F R
EM: stahr@ocean.washington.edu
AF: University of Washington, School of Oceanography Box 357940, Seattle, WA 98195-7940 United States
AB: Significant differences exist between hydrographic transects made in 2004 and 2005 at the Endeavour Segment Integrated Study Site on the Juan de Fuca Ridge. Sections that describe the conditions above the segment utilize twenty-one nearly uniformly spaced hydrographic stations from south of Mothra to north of the Sasquatch hydrothermal vent fields. Criteria used in choosing station locations included depth, ~500 m spacing from other stations, and being centrally located in the valley. The resulting sections allow for rapid evaluation of the characteristics of the neutrally buoyant plume over each of the vent fields. Preliminary results indicate heat content over the northern vent fields, Salty Dawg and Sasquatch, significantly increased between the summers of 2004 and 2005. In 2004, the plumes over these vent fields were barely discernable while in 2005 prominent plumes existed with potential temperature anomalies over 0.1°C. Vent data being obtained by other RIDGE 2000 and UW Keck investigators will help constrain the underlying causes of these changes. Isopycnals in the 2005 sections are also elevated along the entire length of the transect by approximately 50 m or more. The potential temperature anomaly section from 2005 is indicative of a thicker (about 75 m) neutrally buoyant plume and substantially more heat at the north end of the valley. In 2004, the shallowest plume depth was 1900 m contrasted with 1830 m in 2005.
DE: 3015 Heat flow (benthic)
DE: 3017 Hydrothermal systems (0450, 1034, 3616, 4832, 8135, 8424)
DE: 3035 Midocean ridge processes
DE: 4536 Hydrography and tracers
DE: 4562 Topographic/bathymetric interactions
SC: Tectonophysics [T]
MN: Fall Meeting 2005