The source of Benguela Niños in the South Atlantic Ocean

The intermittent occurrence of anomalous warm events in the upwelling regions of the Pacific - El Niños - has been intensively studied. Pacific Niños have striking effects on the local ecosystem, hence on the fisheries, and on rainfall. Similar dramatic events have been observed in the South Atlantic off the coasts of Angola and Namibia and named Benguela Niños. They tend not to occur in unison with their Pacific counterpart and may thus have unrelated forcing mechanisms. Using an ocean general circulation model, forced by real winds and verified with satellite data, it is shown that Benguela Niños are generated by specific wind stress events in the west-central equatorial Atlantic, and progress from there as subsurface temperature anomalies that eventually outcropped only at the south-west African coast. These results suggest that it now may be possible to predict the occurrence of these disruptive events with a leadtime of 2 months.