A see-saw variability in tropical cyclone genesis between the western North Pacific and the North Atlantic shaped by Atlantic multidecadal variability

Abstract Variabilities in tropical cyclone (TC) activity are commonly interpreted in individual TC basins. We identify an anti-phase decadal variation in TC genesis between the western North Pacific (WNP) and North Atlantic (NA). An inactive (active) WNP TC genesis concurs with an enhanced (suppressed) NA TC genesis. We propose that the trans-basin TC connection results from a subtropical east-west ‘relay’ teleconnection triggered by Atlantic multidecadal oscillation (AMO), involving a chain atmosphere-ocean interaction in the North Pacific. During a negative AMO phase, the tropical NA cooling suppresses local convective heating that further stimulates a descending low-level anti-cyclonic circulation in the tropical NA and eastern North Pacific as a Rossby wave response, inhibiting the NA TC genesis. Meanwhile, the anomalous southwesterly to the western flank of the anomalous anti-cyclonic circulation tends to weaken the surface evaporation and warm the SST over the subtropical eastern North Pacific (southwest-northeast oriented zone from the tropical central Pacific to the subtropical west coast of North America). The SST warming further sustains a cyclonic circulation anomaly over the WNP by local atmosphere-ocean interaction and the Bjerknes feedback, promoting the WNP TC genesis. This trans-basin linkage helps us interpret the moderate amplitude of variations in TC genesis frequency in the Northern Hemisphere.