Fluxes of Heat and Salt from Endeavour Segment Vent Fields:
Discrete Measurements as a Test of the Sea Breeze "Flux Meter"
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
Hydrothermal Vents Marine Protected Area.
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
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
Full Proposal (pdf)
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.
- University of Washington
- Woods Hole Oceanographic Institution
- Dana Yoerger, WHOI Principal Investigator
- Al Bradley
- Institute of Ocean Sciences, Fisheries and Oceans Canada
- Geological Survey of Japan, Marine Geology Department
The first results from the project will come after servicing the moorings in Summer 2004.
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.