Changes in ENSO teleconnections impacting on surface winds along the Northeastern Tropical Atlantic

Wind stress in the Northeastern Tropical Atlantic (NETA) shows pronounced interannual variability during the coastal upwelling season (February–May). ENSO drives most of this variability, although its influence is non-stationary, reflecting shifts in the underlying teleconnection pathways. During 1960–1990, La Niña events forced an atmospheric Rossby wave train resembling a North Atlantic extension of the Pacific–North American pattern. This pattern strengthened northeasterly winds along the Northwest African coast and enhanced Ekman Transport (ET), intensifying coastal upwelling. The present study shows a dramatic change in the ENSO teleconnection driving wind anomalies in the NETA in recent decades (1994–2024). While ENSO-driven Ekman Pumping (EP) has always been present in the region, the ENSO influence on ET has weakened substantially since the 1990s due to a reorganization of the atmospheric teleconnection pathway. For 1994–2024, the Rossby wave propagating toward the Atlantic produces weaker alongshore northeasterly winds and thus ET. This change could be due to different factors. On the one hand, stronger ENSO-related upper-level divergent winds in the western equatorial Pacific have generated a Rossby Wave Source near the East Asian coast. On the other hand, Sea Surface Temperature (SST)-driven changes have modified the jet stream intensity and teleconnection waveguides reaching the NETA. These results have implications for the seasonal prediction of upwelling and marine productivity in the region.