A numerical study of axisymmetric flow regimes in a rotating annulus with local convective forcing

We present a numerical study of 2D axisymmetric flows in a rotating annulus convectively forced by local thermal forcing via a heated annular ring at the bottom near the external wall and a cooled circular disk near the centre at the top surface of the annulus. Two vertically and horizontally displaced heat sources/sinks are arranged so thatstatically unstable Rayleigh-Bénard convection would be induced above the source and beneath the sink, emulating local vigorous convection in the tropics and polar regions in the Earth’s atmosphere or oceans with a stably-stratified baroclinically unstable zone in mid-channel. Several distinct flow regimes are identified and characterized with reference to variations in the (squared) ratio P of Ekman layer thickness to the thermal boundary layer thickness (proportional to rotation rate Ω). Corresponding scalings for quantities such as azimuthal velocity and Nusselt number with P are consistent with convective transfer ∼ Ra0.329±0.018 and control of meridional transport by Ekman layers in rotating flow.