Multidecadal Variations in the East Asian Winter Monsoon and Their Relationship with the Atlantic Multidecadal Oscillation since 1850

Abstract This study investigates the characteristics and physical mechanisms of multidecadal variations in East Asian winter (December–February) monsoon (EAWM) since 1850 based on multiple observational reanalysis datasets. The results indicate that EAWM undergoes weakening during periods 1869–1919 1986–2004 but strengthening period 1920–85. Similar evolutions can be observed time series area-averaged surface air temperature over Asia. Associated with variations, a quasi-barotropic Rossby wave train originating from subtropical North Atlantic propagating across Eurasian continent to Northeast Asia also experiences phase shifting at same time. In its positive phase, low-level anticyclonic anomaly northern causes stronger Siberian high; mid- high-level cyclonic anomalies deepen trough strengthen jet stream, respectively. Thus, is conducive EAWMs vice versa. diagnostic analysis source indicates upper-tropospheric divergence favor excitation this train, feedback forcing high-frequency eddies plays important roles maintenance. addition, oscillation (AMO) induce similar continent, through which it further modulates EAWM. Warm phases AMO are favorable for colder midlatitude