Atlantic–Pacific Multidecadal Variability Modulates the North Atlantic Oscillation–North Atlantic Tripole Relationship

Abstract The North Atlantic Oscillation (NAO)–North Atlantic Tripole (NAT) relationship has revealed distinct fluctuation on the decadal time scale, with its mechanism remaining unclear. We in this study suggest the NAO–NAT relationship is combinedly modulated by the Atlantic Multidecadal Variability (AMV)–Pacific Decadal Oscillation (PDO), and the latent heat flux (LHF) plays a key role during the process. The cyclonic anomaly over the subtropical North Atlantic as the consequence of positive AMV and negative PDO enhances the LHF on the decadal time scale, which promotes consistent covariation in the atmospheric baroclinicity and the eddy‐mean flow interaction. It leads to positive feedback manifesting the NAO–NAT relationship. Conversely, the negative AMV and positive PDO can symmetrically weaken the NAO–NAT relationship. The above mechanism is verified by model experiment. This study offers new insights on the air‐sea interaction modes between Pacific and Atlantic Oceans, as well as their trans‐scale multi‐basin linkages.