Combined Effect of Sea Surface Temperature Anomalies in the Central–Eastern Pacific and North Atlantic on Wintertime Extreme Precipitation over Southeast China

Based on daily precipitation observations and NCEP reanalysis data for the period of 1961–2020, the interannual variability of winter extreme precipitation frequency (EPF) over Southeast China (SEC) and its possible association with sea surface temperature (SST) anomalies is investigated. The results show that winter EPF over SEC is closely linked to a south–north dipole pattern and the Philippine anomalous anticyclone. The south–north dipole pattern is characterized by a cyclonic anomaly over southern China and an anomalous anticyclone over Northeast Asia. The south–north dipole pattern deepens the India–Burma trough and weakens the East Asian trough, facilitating abundant water vapour conditions over SEC. The south–north dipole pattern is not a localized phenomenon but rather an integral component of two Rossby wave trains: the Indo-western Pacific and East Asia (IWP–EA) pattern and the circumglobal teleconnection (CGT) pattern. The IWP–EA pattern is derived from the northern Indian Ocean and is related to ENSO events. The CGT pattern is associated with ENSO and an east–west SST anomaly pattern in the North Atlantic Ocean (NAEW). Therefore, both El Niño and the positive NAEW pattern jointly trigger the CGT pattern and the IWP–EA pattern, imposing a synergistic effect on the winter EPF over SEC.