Pacific Decadal Oscillation Modulates the Relationship Between Pacific Meridional Mode and Tropical Cyclone Genesis in the Western North Pacific

Pacific Meridional Mode (PMM) is known to be significantly correlated with tropical cyclone (TC) genesis over the western North (WNP), while stability of their relationship remains unknown. Here we found that nonstationary, which depends on phase Decadal Oscillation (PDO). During PDO warm phases, PMM-emanated cyclonic circulation and ascending motion can propagate entire WNP due enhanced background convection. In contrast, during cold PMM-resulted are confined eastern WNP, compensated descending prevails in WNP. Accordingly, PMM-induced consistent (inconsistent) changes large-scale conditions across act strengthen (weaken) between PMM TC (cold) phases. The result provides further guidance for improving seasonal prediction genesis.