Generation of inertia-gravity waves by a time-dependent baroclinic wave in the laboratory

Abstract

A novel technique is used to visualise and measure a barochnically unstable flow in a two-layer, rotating annulus experiment in the laboratory with very high resolution in space and time. It was found that small-scale, high-frequency waves were generated in certain preferred locations within the flow by a baroclinic wave undergoing periodic amplitude vacillation. These fast waves have been investigated in terms of their dispersion relation and shown to be consistent with inertia-gravity waves, generated in association with geostrophic adjustment. Phase-portrait analyses of these experiments indicate that the resulting vacillatory behaviour of the large-scale flow remains consistent with low-dimensional dynamics, despite the generation of these small-scale inertia gravity waves.