Figure 5: The meridional PV advection by ACs.

The abscissa represents zonal sections across the AC centre. Recall that [−1, 1] defines the eddy core. (a,d,g) The tangential velocity of AC ( in m s⁻¹); (b,e,h) the PV anomaly from the zonal-averaged background climatology ( in 10⁻¹⁰m⁻¹ s⁻¹); and (c,f,i) the eddy-advective transport ( in black and red dots in 10⁻¹⁰s⁻²). The black dots are within the eddy core [−1, 1] where the integrated eddy flow transport is offset, and the red dots are in ±[1, 2]. The eddy-trapping transport (C_y in blue dots) is superimposed in the right panels. (a–c) for Argo observations, (d–f) for one AC and (g–i) for 14 ACs in OFES. Here we choose one AC from the model (d–f) that has the eddy PV flux close to that of the AC in the field to compare the zonal asymmetry of PV and tangential velocity. The green lines denote the average for each Δx=0.1 bin calculated with the Argo sampling. The yellow lines in (d–i) are the exact calculation of the time average based on the full model data (Methods).