Understanding the decrease in Atlantic OHT south of 60N
As can be seen in Fig. 1 of the Atlantic and Pacific SST experiments, the mean Atlantic OHT increases north of 60N but decreases south of 60N for the wide and middle domain experiments. We think that is due to a decrease in the North Atlantic mixing (Fig. 8 of the SST restoring experiments) and weakening of the Atlantic Meridional Circulation (Figs. 9 and 10 of the Atlantic and Pacific SST experiments), following the SST increase. Interestingly, the vertical profiles of the Atlantic meridional stream function (AMSF) show a weakening at all depths south of 60N and an increase in the upper layer (first 500m) north of 60N with a weakening below in the wide and middle domain experiments (Fig. 10 of the Atlantic and Pacific SST experiments).