Convective circulation in mesoscale abyssal basins

Abstract

Deep circulation in natural water basins that are smaller than the large global abyssal ocean, but bigger than a Rossby radius of deformation is both scantily documented and poorly understood. For buoyancy driving alone, angular momentum balance dictates that currents of both cyclonic and anticyclonic sense of circulation must exist, although both senses need not be of the same magnitude in the interior. Three laboratory experiments performed on a rotating turntable have been found with interior velocities that demonstrate layers with alternating cyclonic and anticyclonic azimuthal circulation. In one example an internal thermocline implies there is a set of two stacked meriodonal cells of opposite sign. Numerical results and laboratory data display qualitative agreement over a wide range of parameters. Quantitative comparison is within roughly two in the worst cases, but somewhat better for other cases. An argument based upon energetics is advanced which produces a velocity scale in rough agreement with some of the laboratory and numerical results.