A coupled ocean–atmosphere laboratory model of the Antarctic Circumpolar Current

A thermally-driven rotating annulus with two immiscible fluid layers is used as a laboratory analogue for ocean–atmosphere coupling in the Southern Ocean region. The laboratory facility can be tuned to produce a separation in scales between the two layers, and flow in each layer qualitatively resembles observed parameter regimes. The model effectively allows the lower (ocean) layer to be driven by both thermal and momentum forcing, and these two components can be independently varied to investigate the dynamics of the system. The results show that it is plausible to drive a strong circumpolar ocean flow with thermal forcing alone. The addition of momentum forcing increases the circumpolar transport, but only up to a limit, consistent with existing eddy-resolving simulations of the Antarctic Circumpolar Current. Thus it is demonstrated that laboratory models of coupled ocean–atmosphere flows can contribute to the range of tools available to understand climate-scale phenomena.