HR: 15:10h
AN: OS53B-07    [Abstracts]
TI: Understanding Mixing and Entrainment of Oceanic Overflows Using Laboratory Experiments
AU: * Ecke, R E
EM: ecke@lanl.gov
AF: Los Alamos National Laboratory, Center for Nonlinear Studies, MS-B258, Los Alamos, NM 87545, United States
AU: Odier, P
EM: odier@lanl.gov
AF: Los Alamos National Laboratory, Center for Nonlinear Studies, MS-B258, Los Alamos, NM 87545, United States
AU: Chen, J
EM: jchen@lanl.gov
AF: Los Alamos National Laboratory, Center for Nonlinear Studies, MS-B258, Los Alamos, NM 87545, United States
AU: Rivera, M K
EM: mkrivera@lanl.gov
AF: Los Alamos National Laboratory, Center for Nonlinear Studies, MS-B258, Los Alamos, NM 87545, United States
AB: Oceanic overflows are important elements of the Earth's global thermohaline circulation but the mixing and entrainment that occur for such overflows is poorly understood. In particular, as overflow water moves down an inclined slope its stability is governed by the competition between stratification, which stabilizes the flow, and vertical shear, which tends to destabilize the flow. The properties of our laboratory experiment are designed to mimic oceanic overflows to the extent achievable on laboratory-accessible length scales. The flow exits a nozzle and flows along an inclined plane such that there is gravitational forcing of the flowing gravity current. We inject turbulent velocity fluctuations into the fluid using an active rotating grid prior to its exit from the nozzle, thereby generating a turbulent boundary layer condition at the plane boundary. The Taylor Reynolds number of the flow coming out of the nozzle is about 150. Velocity and density fields are measured simultaneous using particle image velocimetry and planar laser induced fluorescence. The flow structure and dynamics of mixing at different downstream locations are investigated for a standard stratified case and a non-stratified case where there is no density difference between the injected current and the ambient fluid. The role of turbulence is examined by comparing cases of turbulent and the laminar gravity currents. The implication of these results for ocean simulations will be presented.
DE: 4553 Overflows
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting