Pacific–East Asian Teleconnection. Part II: How the Philippine Sea Anomalous Anticyclone is Established during El Niño Development*

The anomalous Philippine Sea anticyclone (PSAC) conveys impacts of El Nin o to east Asian climate during the mature and decay of an El Nin o (from the winter to ensuing summer). It is shown that the anomalous PSAC forms in fall about one season prior to the peak El Nin o; its strength increases with the El Nin o intensity and its sign reverses during a La Nin a. The PSAC formation concurs with abnormal deepening of the east Asian trough and with increasing number of northward recurvature of tropical storms in the western Pacific. The PSAC establishment is abrupt, coupling with a swing from a wet to dry phase of an intraseasonal oscillation (ISO) and often concurrent with early retreat of the east Asian summer monsoon. The ISO becomes inactive after PSAC establishment.