Buoyancy flux estimates for a tidal channel
Date
2002
Authors
Macoun, Paul
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Abstract
A parameterization of the vertical flux of density based upon the physics of oceanic mixing processes is required for a wide variety of practical problems, but remains an elusive goal. In August 2000, the horizontal microstructure profiler TOMI was used over the course of six days, in Sansum arrows, to make simultaneous measurements of temperature, conductivity, vertical velocity and their fluctuations. These data provide average estimates of the heat and salt flux, and thus the buoyancy flux, and estimates of the rate of dissipation of kinetic energy. Concurrent profiles of vertical shear and in-situ estimates of the buoyancy frequency provide the means to relate the ratio of buoyancy flux to dissipation rate, to the Froude number, and to the buoyancy Reynolds number over a wide range of these parameters. The ratio of buoyancy-to kinetic energy production reaches 0. 77 in San.sum Narrows, and is generally larger than the value of 0.2 assumed to apply to the open ocean. It also appears to decrease with increasing buoyancy Reynolds number, and peaks in a small range in Froude number.