Color contours showing the horizontal spatial distribution of the zonal wind at P = 50 mbars at times indicated with red dots in Fig. 9, namely t = 223.3 (left panel) and t = 224.7 (right panel). Black contours plots the meridional velocity fluctuations v′. Contours are shown every 50 m s^-1 from −100 to 100 m s^-1 on the left hand side panel and every 100 m s^-1 from −400 to 400 m s^-1 on the right hand side panel. In both panels, positive (resp. negative) contours are shown with solid (resp. dashed) lines and the zero contour is omitted.