Recent Opposite Trends of Atmospheric Rivers Over East Asia and Western North Pacific Driven by the Pacific Decadal Oscillation

Abstract

Atmospheric rivers (ARs) in East Asia have garnered increasing attention for their crucial roles in understanding extreme precipitation events and regional hydrological cycles. Here, we investigate the summer AR frequency over the East Asia‐western North Pacific region (EA‐WNP) during 1959–2022. Interestingly, the results show that the AR frequency over the two regions experienced opposite variations, with the boundary between them at around 135°–140°E. On interdecadal timescales, such variations are mainly synchronized with a zonal dipole pattern characterized by cyclonic (anticyclonic) anomalies centered to the northwest of Taiwan and anticyclonic (cyclonic) anomalies centered to the southeast of Japan. This interdecadal dipole pattern is induced by interdecadal changes in the western North Pacific subtropical high under different Pacific Decadal Oscillation (PDO) phases. Particularly, the internal variability accounts for about 77–90% of the observed trends in high response areas. The displacements of ARs are also consistent with the opposite trends of precipitation over EA‐WNP. ARs exert a dominant influence on the precipitation trend in the WNP region but a weaker contribution to the precipitation trend in the EA region, which reflects the different impacts of ARs on EA and WNP precipitation. These results indicate that the PDO has the potential for predicting EA‐WNP ARs on interdecadal timescales, and the opposite AR trends are crucial in understanding the complexity of precipitation over the EA‐WNP region.