Southern China Winter Rainfall Modulated by South China Sea Warming

Abstract

New insight into the contribution of anomalous South China Sea (SCS) warming is proposed to understand strong southern China (SC) winter rainfall. El Niño events, which weaken the East Asian winter monsoon (EAWM), favor SC winter rainfall. However, the changes in SC winter rainfall are not always in phase with the El Niño-Southern Oscillation, making the prediction of East Asian climate challenging. Here, we show that the increased moisture associated with the warming SCS induced by the weakening western boundary current leads to increased meridional moisture transport to SC. Particularly, during the El Niño mature winter phase, this effect works jointly with a weakened EAWM to determine an increased rainfall over SC. Therefore, we suggest that the thermal state of the SCS should be considered when large-scale tropical ocean-atmosphere variability is utilized to predict SC winter rainfall.