Pacific thermocline bridge revisited

The coupling on decadal time scales of the midlatitude and tropical Pacific via an oceanic 'bridge' in the thermocline is investigated using ocean gen eral circulation model hindcasts and a coupled ocean atmosphere model. Resu lts indicate that in the tropics decadal anomalies of isopycnal depth are f orced by Ekman pumping and are largely independent of the arrival of subduc ted anomalies in the thermocline that originate in the mid-latitudes of eit her hemisphere. In the coupled model, temperature anomalies on isopycnals s how little coupling from the tropics to the northern hemisphere, but are la g correlated between southern hemisphere mid- and low-latitudes. However, a nomaly magnitudes on the equator are small. These results suggest that the oceanic 'bridge' to the northern hemisphere explains only a small part of t he observed decadal variance in the equatorial Pacific. Coupling to the sou thern mid-latitudes via temperature anomalies on isopycnals remains an intr iguing possibility.