Higher order dynamics of baroclinic waves

Instabilities in the form of baroclinic waves occur in a rotating cylindrical annulus cooled from within. Flow visualisation studies and LDV-measurements of the radial velocity component were carried out in an annulus with an aspect ratio of 4.4. The flow undergoes transitions from the laminar stable state through baroclinic waves, both stable and time-varying, to an irregular state. Based on the time series of the radial velocity at fixed point in the rotating annulus, the attractors of the flow match previous results based on temperature measurements. The bifurcation diagram of extrema in the radial velocity shows the existence of low dimensional chaos at the transition from the axisymmetric flow to periodic baroclinic waves. This bifurcation scenario at low rotation rates is substantially different from the nonlinear behaviour of Taylor-Couette flow.