Rotating convection and the oceanic general circulation

This dissertation describes a series of laboratory and numerical experiments designed to examine the small scale physics important in convection which might have bearing on large scale oceanic circulation.; The interaction of a plume of dense fluid with a pycnocline has been examined with a series of two-layer laboratory experiments. The heat-loss forced, salt-stratified system is especially interesting; in such a system even a relatively small interfacial density jump may prevent overturning, since non-linearities in salt water's equation of state make the density jump greater as the system cools.; Convection in a slot is an interesting laboratory analogy to the way in which the thermohaline circulation builds the oceanic thermocline. In a set of laboratory experiments, it was found that the entrainment which a descending plume experiences is critical to determining the final density and velocity structure in the tank. Changes in this entrainment, forced by sloping bottom topography, impede entrainment by allowing the fluid to descend in a boundary layer. The descending plume can "lift off" the bottom and become the laboratory equivalent of an intermediate water mass under some circumstances.; A number of these features can be seen in the results from a two-dimensional, non-hydrostatic numerical model designed to be similar to the laboratory experiment. Additionally, the numerical model demonstrates the energy balance of the system, and the way in which the configurational potential energy of the system is tapped to initialize the flow. Comparison with a hydrostatic version of the same model demonstrates some of the problems with the meridional flow and density fields predicted by such models.; Finally, the way in which convection is parameterized in large scale oceanic general circulation models is examined. It is shown that model deficiencies arise from neglecting information of vertical propagation speeds in the convecting system. This can lead to inaccuracies in the temperature and salinity fields of such models.