A Salt Finger Tracer Release Experiment - Analysis

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ABSTRACTOCE-0350743This research team successfully completed a two-year tracer and turbulence field study in the Tropical North Atlantic Ocean and Caribbean Sea, in an area prone to salt-finger instability. Preliminary results from the experiment are that the vertical diffusivity of the passive tracer in the area showing signs of salt-fingering was 4-5 times greater than elsewhere. Diffusivity for heat was about half that of the tracer, and that the energy dissipation was much smaller than would be expected for shear-driven mixing, both of which are expected for mixing due to salt fingers. This project is for the extended analysis of the data from the field study with the following objectives: to accurately determine the vertical mixing of tracer and heat within the staircase region and outside of it; to evaluate the roles of shear and salt finger instability in the formation and maintenance of staircases and the enhancement of mixing; to develop a parameterization of diffusivities of heat and salt in regions of the ocean susceptible to salt fingering for use in numerical models; to evaluate the role of enhanced mixing in the staircase region in regional transport of heat and salt and in water mass modification; to analyze the efficient zonal dispersion of the tracer patch, and lateral mixing and stirring of the tracer patch with the help of numerical models; and to publish the results of the research. The project will have broader impacts through the training of a graduate student, international collaborations and contribution to parameterizations for modeling.