Laboratory and Numerical Experiments on the Effects of Topography and the B-effect on Baroclinic Flows

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The goal of this research is to produce a series of laboratory and numerical experiments to determine the effects of large-scale topography on baroclinic flows in thermally-driven, rotating fluids. The B-effect will be simulated with radially sloping bottom and top boundaries without bottom topography. Starting with simple 2-wave bottom topography, the PIs will progress to increasingly more complex topography using the amplitudes and phases of the dominant modes of the earth's topography in the middle latitudes of the Northern Hemisphere. Numerical models will be modified to include waves over bottom topography and will be integrated in parallel with the laboratory experiments. These models will incorporate two versions of the B-effect. In one version, the B-effect will be incorporated in the governing equations as it appears in the equations for atmospheric flow. In the other, it will be incorporated in the boundary conditions by assuming radially sloping bottom and top boundaries as simulated in the laboratory experiments. The numerical solutions obtained with both forms of B will be compared in order to assess the degree to which the sloping boundaries in the experiment capture the essential influence of B on baroclinic flows. Much interest in the area of geophysical fluid dynamics research is currently focused on study of topography and rotation induced planetary wave regimes, and their role in the fluctuations of the mean zonal wind. One problem with the current batch of theoretical studies of topographic instability is that there is very little by the way of suitable observations for verifying predictions of theoretical models. The importance of this project is that laboratory annulus experiments provide a powerful means for simulating fluid behavior under various boundary conditions and validating theory. The work proposed by Dr. Pfeffer and colleagues will investigate through a series of laboratory annulus and numerical experiments the effects of large scale topography on thermally-driven rotating fluids.