Sea Breeze

Fluxes of Heat and Salt from Endeavour Segment Vent Fields: Discrete Measurements as a Test of the Sea Breeze "Flux Meter" Hypothesis

A sea breeze occurs when the land surface heats more rapidly than the adjacent water, setting up an thermally driven convection current drawing a cool sea breeze over the land. We hypothesize that, in the same way, hydrothermal vents within the confines of the axial valley of central Endeavour Segment entrain ambient waters driving flow of fluid into the valley. Measures of this flow may be an effective proxy for monitoring hydrothermal output.

The Sea Breeze program is a component of the RIDGE 2000 Integrated Study Site (ISS) on the Endeavour Segment, Juan de Fuca Ridge within the Canadian Endeavour Hydrothermal Vents Marine Protected Area.

Rationale

Measurement of the fluxes of heat and materials that tie geological forcing to biological response is central to addressing the major questions posed in the Endeavour Integrated Study Site implementation plan. We propose to acquire two sets of complementary observations: the vertical fluxes of fluid mass, heat and salt rising from Endeavour Segment vent fields and the lateral transport of fluid mass within the axial valley. Taking advantage of the topographic constraints of the Endeavour Segment, we will use these observations to evaluate whether the mean subinertial component of the lateral fluid flux into the valley balances the upward, buoyancy-driven fluid flux from the vent fields--our "sea breeze" hypothesis.

A strong correlation could provide a means of making continuous, remote proxy measurements of the integrated fluxes from the vent fields, thereby serving as a "flux meter." In addition to testing the sea breeze hypothesis, the data will help address a number of other significant questions concerning how the flux of heat from Endeavour Segment evolves, the rates of change associated with phase separation and segregation, fluxes of substrates used as energy sources by plume microbiota, and characteristics of the regional circulation relevant to larval dispersal.

The project continues a long-standing collaboration of UW and DFO in this Canadian Marine Protected Area. The data collected would benefit a number of other programs, on-going and proposed, within the Endeavour Segment ISS. We would continue to provide research opportunities for graduate and undergraduate students. We will host secondary school teachers, under the auspices of the REVEL program, on our 2004 cruise. REVEL provides opportunities for teachers to participate in research, to bring increased knowledge and excitement to their classrooms, to develop innovative curricular materials and to establish on-going partnerships with active researchers.

Full Proposal (pdf)

Operations

The vertical fluxes from the vent fields will be measured by establishing appropriate control volumes around them and using the autonomous vehicle ABE, complemented by precisely navigated CTD observations and nearby current meter moorings, to assess the temperature, salinity and velocity fields on their boundaries. Our survey of Main Endeavour Field in 2000 showed that in ~60 hours of dive time the total vertical flux from the field can be determined to within ~10%. The lateral fluid flux will be measured with a dense array of conventional current meter moorings and up-looking acoustic Doppler current profilers. This array will be deployed in summer 2003, serviced while conducting the ABE surveys in summer 2004, and recovered in summer 2005.

2003	July 23-August 3	CCGS John P. Tully	Metadata \| Mooring Locations \| Pictures
2004	June 14-July 13	RV Atlantis	WHOI Cruise Synopsis Document
2004	July 9-July 19	CCGS John P. Tully
2004	September 13-24	CCGS John P. Tully
2005	tbd	CCGS John P. Tully

People

University of Washington
- Russ McDuff, UW Principal Investigator
- Fritz Stahr
- Veronique Robigou, REVEL Coordinator
Woods Hole Oceanographic Institution
- Dana Yoerger, WHOI Principal Investigator
- Al Bradley
Institute of Ocean Sciences, Fisheries and Oceans Canada
- Rick Thomson, DFO Principal Investigator
- Steve Mihaly
- Tom Juhasz
- Dave Spear
Geological Survey of Japan, Marine Geology Department
- Ko-ichi Nakamura

Results

The first results from the project will come after servicing the moorings in Summer 2004.

Publications

R.E. Thomson, S.F. Mihaly, A.B. Rabinovich, R.E. McDuff, S.R. Veirs, F.R. Stahr (2003) Plume-induced topographically constrained circulation at Endeavour Ridge: implications for the colonisation of deep hydrothermal vents. Nature, 424, 545-549. pdf of paper, courtesy of Nature.

Sea Breeze is supported by the U.S. National Science Foundation, Grant OCE-0242736, and by Fisheries and Oceans Canada. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation or Fisheries and Oceans Canada.