Impacts of Indo-Pacific Sea Surface Temperature Versus Internal Atmospheric Variability on the South China Sea Summer Monsoon

Abstract

The South China Sea (SCS) summer (i.e., June–August [JJA]) monsoon experiences strong interannual variability, which is modulated by the western North Pacific subtropical high (WNPSH). Large-scale steady-state atmospheric circulations linked to JJA mean Indian Ocean basin and preceding winter–spring (i.e., January–March [JFM]) and JJA mean central Pacific sea surface temperatures (SSTs), as well as internal atmospheric variability, influence the SCS summer monsoon and WNPSH. We compare relative impacts of Indo-Pacific SST and internal atmospheric variability on SCS summer monsoon and WNPSH interannual variabilities. Our results show that internal atmospheric variability is more important than any SST predictor in influencing the SCS summer monsoon and WNPSH variabilities. Also, JFM and JJA mean central Pacific SSTs control the SCS summer monsoon more than JJA mean Indian Ocean basin SST.