Turbulence within a Baroclinic Laboratory Mixed Layer above a Sloping Surface

Abstract

A convection tank (of water) containing a buoyancy-driven turbulent boundary layer was tilted at a 10° angle so that mean-flow shear would occur. This caused shear-stress turbulence production to exceed buoyant production in the central portions of the mixed layer. By photographically tracking nearly neutrally buoyant oil droplets, various statistics of the turbulence were obtained and are presented. Vertical curvature in the shear stress was not at all well balanced by the temperature-gradient or baroclinic term in the lower mixed layer, due to vorticity advection associated with the mean flow becoming more horizontal with increasing height within the mixed layer. There was no significant tendency for the shear or inflection point of the mean upslope velocity profile to promote any oganization in the convection cell patterns or to cause roll vortices.