The internal structure of lateral intrusions in a continuously stratified heat/salt system

Abstract

Laboratory experiments have been performed for a double diffusive system in which opposing vertical gradients of temperature and salinity are heated from one side. Details of the internal structure of the intrusions that form along the heated endwall are discussed. Fingering motions and convective overturns are prominent characteristics of the internal intrusion structure, particularly when the rate of lateral heating is high relative to the strength of the ambient vertical density gradient. Analysis of the overturning scale indicates that the RMS size of the overturns is typically 10%–30% of the total layer thickness. Comparison of the flow inside the convective layers with that which develops in a long box heated and cooled at opposite sides based on the analysis of Jeevaraj and Imberger [J. Fluid Mech. 222, 565 (1991)] shows poor agreement when molecular values of the diffusivity and viscosity are used in the theory. However, moderate increases in the diffusivity values (to account for increased vertical mixing) give good agreement between the experiments and theory. Building on the results of Schladow et al. [J. Fluid Mech. 236, 127 (1992)], further evidence of the ability of the intrusions to continue propagating following removal of the endwall heating is presented. Modification of the flow field ahead of the intrusion fronts can create conditions for which the stability ratio, Rρ, drops below a critical value, resulting in continued propagation of the intrusions.

Alleviation of hypoxia by biologically generated mixing in a stratified water column

“…A single probe with a conductivity and temperature sensor was used to determine the fluid density at each height. However, the response time on the temperature sensor was slower than the conductivity sensor (McDonald 1992). Due to the dependence of salinity on the conductivity and the temperature, densities calculated in regions where temperature and salinity changed rapidly required correction (e.g., the interface between the two layers).…”

“…Due to the dependence of salinity on the conductivity and the temperature, densities calculated in regions where temperature and salinity changed rapidly required correction (e.g., the interface between the two layers). To correct the temperature signal lag, a signal filter function developed by Fozdar et al was used (Fozdar et al 1985;McDonald 1992). The temperature signal was filtered following the equation:…”