Ratio of the wave action flux above and below the critical level against the Rossby number and the inertial frequency for R >1∕4 (left panel) and R < 1∕4 (right panel) when the box is at the pole. As in Fig. 7, k_x = k_z = 0.1 and hatchedzones represent areas without critical levels. Again, crosses indicate the set of parameters chosen to analyse the behaviour of the velocity in the three-layer model.