Rotating convection driven by differential bottom heating

Abstract

Convection experiments were carried out in a rectangular tank as a model of oceanic meridional overturning circulation. The objective was finding a relation between the meridional heat flux and thermal forcing. To make the meridional heat flux estimate possible, the heat flux was fixed at one bottom end of the tank using an electrical heater. Temperature was fixed at the other end using a cooling plate. All other boundaries were insulated. In equilibrium, the heat input to the fluid H was the same as the meridional heat flux (heat flux from the source to the sink), so it was possible to find a scaling law relating H to the temperature difference across the tank δT and rotation rate f. The experimental result suggests that the meridional heat transport in the experiment was mostly due to geostrophic flows with a minor correction caused by bottom friction. When the typical values of the North Atlantic are introduced, the geostrophic scaling law predicts meridional heat flux comparable to that estimated in the North Atlantic when the vertical eddy diffusivity of heat is about 1 cm2 s-1.