Indo-western Pacific Ocean capacitor events recorded by coral proxies in the South China Sea

Abstract

The Indo-western Pacific Ocean capacitor (IPOC) effect induces coherent climate variations over the Indo-western Pacific Ocean with significant sea-surface temperature (SST) anomalies over the South China Sea (SCS). Most IPOC events are related to El Nin∼o-Southern Oscillation (ENSO), occurring in the post-ENSO years. The coral δ18O and Sr/Ca precisely recorded climate variations as proxies for SST. This study investigated the IPOC via a reduced major axis (RMA) regression analysis based on coral records in the SCS. The coral records of Yongxing Island show a double SST peak during El Niño events after the 1960s, one in the mature phase and the other in the post-El Nin∼o summer. Tropical Indian Ocean warming persists into summer and anchors an anomalous anticyclonic circulation over the western North Pacific, extending the ENSO effect on the SCS SST through the IPOC effect, despite the decay of El Nin∼o. The corals from Yongle Atoll, Dongsha Atoll, and the region off central Vietnam well recorded the IPOC impacts associated with two strong El Nin∼o events (2009–2010 and 1997–1998) on SST anomalies in summer. According to coral records off central Vietnam, the 1959 IPOC effect occurred without an antecedent El Nin∼o event. The results show that coral proxies could capture the IPOC events in the SCS and prove that IPOC could act as an intrinsic climate mode in the Indo-western Pacific Ocean.