Summer Surface Warming Driven by the Strong El Niño in the South China Sea

Abstract

Abstract The interannual variability of sea surface temperature (SST) in the South China Sea (SCS) exhibits two peaks around January and August in the subsequent year of the El Niño. We show that the second basin-scale summer SST warming feature peaked in August [+1] is only distinct after strong El Niño events, not regular El Niño events. The upper ocean heat budget analysis demonstrates that the abnormal Ekman advection (Eka) dominants the second warming features during the whole developing stages from June [+1] to August [+1], while the abnormal geostrophic advection (Goa) leads to the warm tendency in June [+1], by reducing the Vietnam coastal upwelling. The local dynamical effects of abnormal Eka and Goa in the SCS are attributed to the advanced abnormal easterly wind breakout in the western Pacific, coincided with the development of West North Pacific anomalous anticyclone (WNPAC) in response to strong El Niño. Our results suggest that the second warming features of SCS SST during the next summer are the footprints of strong El Niño events via the establishment of the WNPAC, which is tightly related to Indo-Pacific remote processes.