Direct Comparison of Laboratory and Numerical Simulations of Idealized Oceanic Overflows

Oceanic overflows occur when dense water flows down a continental slope into less dense ambient water. The resulting density driven plumes occur naturally in various regions of the global ocean and affect the large-scale circulation. General circulation models currently rely on parameterizations for representing dense overflows due to resolution restrictions. These parameterizations rely on a detailed understanding of the mixing properties, which is enhanced by studying idealized, small-scale models of overflows. The work presented here involves a direct qualitative and quantitative comparison between physical laboratory experiments and lab-scale numerical simulations. Laboratory experiments are conducted using a rotating square tank customized for idealized overflow and a high-resolution camera mounted on the table in the rotating reference frame for data collection. Corresponding numerical simulations are performed using the MIT general circulation model (MITgcm) run in the non-hydrostatic configuration. Resolution and numerical parameter studies are conducted, which ensures that the laboratory conditions are accurately reproduced in the numerical simulations. Laboratory and computational experiments are compared across a wide range of physical parameters, including Coriolis parameter, inflow density anomaly, and dense inflow volumetric flow rate. The results are analyzed using various metrics including plume velocity, plume area, initial angle of descent, plume path, and tracer concentration of the plume.