Far East precipitation associated with summer Asian-Pacific Oscillation

The Asian-Pacific Oscillation (APO) is a dominant summertime atmospheric teleconnection pattern over the Northern Hemisphere midlatitudes. While its impacts on East Asian summer climate ar e well established, the APO’s modulation of higher-latitude precipitation over the Far East and associated cross-seasonal effects remain unclear. Using multiple datasets spanning 1940–2022, this study investigated the linkage between the summer APO and the Far East precipitation from summer to the subsequent autumn. A positive APO phase corresponds to above-normal precipitation over the Far East in both summer and autumn. In summer, the APO-related precipitation increase is supported by intensified moisture transport and ascending motion, which jointly provide favorable dynamical and thermodynamic conditions for local precipitation. Additionally, the summer APO excites a deep anticyclonic anomaly over the extratropical Northwest Pacific. This anomaly reduces cloud cover, intensifies downward shortwave radiation, weakens westerly wind stress, and increases oceanic heat uptake, collectively driving significant midlatitude Northwest Pacific sea surface temperature (SST) warming. These positive SST anomalies persist coherently into autumn. During autumn, the enhanced heat release from the persistent warm SST anomalies helps maintain circulation anomalies in the North Pacific–Far East sector, thereby enhancing autumn precipitation over the Far East.