Laboratory Measurements of Heat and Salt Fluxes in Double-Diffusive Interleaving

Florida State University, Tallahassee FL

Investigators

Abstract

ABSTRACT OCE-0242535 Two classes of experiments on doubly diffusive intrusions will be conducted in the laboratory. The first is the intrusive interleaving produced in the classical arrangement of property discontinuity when a sluice-gate is withdrawn which had separated salt-stratified water from sugar-stratified water. (Salt in the laboratory experiment is used as a proxy for cold in the ocean, slow-diffusing sugar as a proxy for ocean salt.). The second is a new arrangement in which a continuous horizontal gradient of salinity is density-compensated by an opposing continuous horizontal gradient of sugar, and interleaving intrusions grow everywhere simultaneously. These experiments will be performed for doudbly-stable, for salt-fingering, and for diffusive stratification. For both classes of flows modern quantitative measurements techniques such as particle-Image Velocimetry for horizontal and vertical components, color polarimetry and synthetic Schlieren for sugar concentration and density field will be used to determine the horizontal and vertical fluxes of temperature (T) and salt (S), as they vary with imposed gradients. The anticipated results of this study are (1) a determination of flux laws relating fluxes of T and S to imposed gradients; (2) a determination of relationship of horizontal to vertical fluxes and (3) a diagnosis of instability mechanisms and test of linear stability theories. The discovery of flux laws which can be scaled up to determine the magnitude of horizontal mixing in oceanic fronts is anticipated. Since the resulting modified waters participate in the global thermohaline circulation, the degree of mixing modifies the poleward transport of heat which is a crucial component of the consequences of global warming. Teaching and training will be promoted through the integration of research results and use of the laboratory facilities in many layers of teaching, including graduate students and undergraduate Honors Science Seminar students projects and an international partnership with the Dept. of Environmental Engineering, University of Genoa.