Fig. 5

Zonally and temporally averaged fields of eddy heat transport and potential vorticity (PV). Panels a–d show heat transport due to eddies by vectors and its convergence by colour, and e–h show PV by colour and potential temperature by contour. For the colouring of PV, a linear scale is used for the range between ±10−8 and a logarithmic scale is used for outside of the range to visualise the positive and negative PV-gradients. The time-average period is 30 Earth days (about 5–7 periods of the superrotation at 60 km height)