Energetic Constraints on Baroclinic Eddy Heat Transport With a Beta Effect in the Laboratory

Abstract

Hypotheses involving energetic constraints and the down-gradient diffusion of heat in eddy parameterization theories are tested by estimating baroclinic eddy transports in rotating annulus laboratory experiments. Particle Imaging Velocimetry measurements are supplemented by numerical simulations to estimate variables not measured directly. The results with a topographic beta effect broadly support Fick's first law, and are consistent with the GEOMETRIC framework in which eddy buoyancy flux is constrained by total eddy energy. With the topographic beta effect, a relatively simple relation is observed between the eddy buoyancy flux and the total eddy energy, with the ratio quantifying the eddy transport efficiency. This efficiency decreases in more complex flow regimes with larger rotation rates, associated with the changing energy partition between eddy available potential energy and eddy kinetic energy. In the absence of a topographic beta effect, more complicated dependencies are found, suggesting roles for other variables.