The response of the East Asian summer rainfall to more extreme El Nino events in future climate scenarios

This study investigates what can be the response of East Asian summer rainfall (EASR) if global warming causes more extreme El Nino events in the future. Two multi-model ensembles are built based on CMIP6 models that project stronger El Nino-Southern Oscillation (ENSO) in the future and CMIP6 models that project no changes in ENSO, respectively. Since the ENSO impact in the EASR is influenced by the Pacific Decadal Oscillation (PDO) phase, the analysis separates extreme El Nino events occurring in different PDO phases. During the negative PDO phase, CMIP6 models that project stronger El Nino events also project enhanced EASR anomalies compared with models that project similar El Nino magnitudes to the present. However, during the positive PDO phase, the difference in the magnitude of the EASR changes between the two ensembles is negligible. To understand which components of the ENSO future changes are influencing the EASR changes, an atmospheric moisture budget decomposition is applied. The results indicate that future changes in ENSO-driven wind circulation anomalies are the major contributor to EASR changes.