The dynamics of the equatorial Atlantic upwelling seasonal cycle under global warming and its potential impact on Pacific ENSO

This study examines how the dynamics of the equatorial Atlantic upwelling seasonal cycle (EAUSC) variate under global warming using Coupled Model Intercomparison Project Phase 5 (CMIP5) simulations. By analyzing the 90-year long-term development of the upwelling seasonal cycle (USC), we found that the weakened semi-annual signal in the eastern Atlantic resulted from wave processes, while the enhanced annual signal in the west is jointly attributable to Ekman and wave processes. Moreover, the contribution of wave (Ekman) processes is projected to significantly increase (decrease) under global warming. In addition, the future weakening of the eastern EAUSC is strongly connected with long-term variations in the Pacific El Niño Southern Oscillation (ENSO). Therefore, clarifying the dynamical process of the equatorial USC is crucial for improving our knowledge of how ENSO might change under global warming.