HR: 1340h
AN: B13A-0196    [Abstracts]
TI: LAUB-FLEX: Circulation in the Lau Backarc Basin Determined by Floats
AU: Lazarevich, P
EM: plazarev@fsu.edu
AF: Florida State University, West Call Street, Tallahassee, FL 32306 United States
AU: * Thurnherr, A M
EM: ant@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, 61 Route 9W, Palisades, NY 10964 United States
AU: Speer, K G
EM: kspeer@ocean.fsu.edu
AF: Florida State University, West Call Street, Tallahassee, FL 32306 United States
AB: During early RIDGE2000 cruises to the Lau backarc basin integrated study site, a number of neutrally buoyant floats have been deployed. The floats are programmed to drift at 1700m, near the depth of the hydrothermal plumes known at the time of deployment. Every 3--4 weeks the floats return to the surface in order to transmit their position as well as auxiliary data back to shore using a network of satellites. The data are made available in near-real time on the web. In contrast to current-meter data, which become available only after recovery of the instruments and which, because of their Eulerian nature, are not very well suited for studying dispersal near topography, the float data yield timely, cost-effective and directly usable information about dispersal in the deep ocean. The available float data after 3 months reveal an intriguing and consistent circulation pattern in the Lau Basin, with predominantly northward flow along the East-Lau Spreading Center. The float-derived circulation is qualitatively consistent with a hydrographic analysis that was carried out during the project proposal, but the available velocities are 2--3 times larger than expected. Assuming that the currently available data are representative and taking typical deep-ocean values for the horizontal eddy diffusivity, implies that dispersal in the Lau Basin is dominated by advection. This inference has important consequences for the biogeography as it implies that dispersal is primarily unidirectional. This is different at other deep-ocean sites, such as the EPR crest and the ridge flank of the MAR, where dispersal is eddy-diffusion dominated and, therefore, inherently omnidirectional.
UR: http://www.ldeo.columbia.edu/~ant/LAUB-FLEX
DE: 4512 Currents
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting