An experimental study of baroclinic wave interactions in a two-layer system

Abstract Baroclinic waves in a rotating two-layer shear flow are observed by measuring fluctuations in the height of the interface using a technique which does not disturb the flow. Decomposition of the shape of the interface into azimuthal Fourier components shows that the wave spectrum is dominated by a single wave number, but other components have significant amplitudes. Nonlinear interactions between these components are isolated by comparing the results with the predictions of a linear stability theory. The observed interactions are reminiscent of those found by Hide, Mason and Plumb (1977) in a different system, thus demonstrating that they are a fundamental property of baroclinic waves.