INTERFACIAL FLUXES AT A GRID-STIRRED DIFFUSIVE INTERFACE

Results from a grid-mixing experiment in a diffusive thermohaline system are described. A model is proposed to separate the effects of interfacial flux and interfacial movement (entrainment) on property changes in the mixed layer and the present results for heat and salt fluxes are compared with previous studies in unstirred diffusive systems. Comparison of an eddy time-scale and a time-scale for development of instability in the interfacial boundary layers suggests a means of determining whether stirring or double-diffusive instability controls the interfacial transports. For the present conditions there was a negligible effect of diffusive stratification on entrainment rates, and interfacial fluxes were increased by the stirring. It is suggested that the ratio R(F)/R(rho), where R(F) is the interfacial flux ratio and R(rho) is the interfacial stability ratio, should be a function of the overall bulk Richardson number, Ri.