Measurement of Turbulent Mixing Along Slope in Stratified Flow

The mixing phenomenon of ocean currents, which have different densities as well as velocities, are important to ocean dynamics and global climate modeling. One example is the outflow of the Greenland-Iceland-Norwegian Seas, where dense Arctic water overflows a ridge and spills downslope in a density-driven plume until it reaches the deep abyss of the Atlantic Ocean. On the way down it mixes with ambient water of different temperature and salinity. This process affects the global thermohaline circulation, which is a significant element in changes of the global climate. Laboratory experiments are conducted to investigate this problem. A turbulent jet is introduced into a water tank along an inclined plate. The density difference between the jet and the tank water produces a stably stratified boundary current. Particle Image Velocimetry (PIV) and Planar Laser Induced Fluorescence (PLIF) are applied to obtain simultaneous measurement of velocity field and density field along the slope at different downstream locations. On-going efforts are also discussed.