Tropical Atmospheric Response of Atlantic Niños to Changes in the Ocean Background State

Abstract

Since the 1970s, Atlantic Niños during boreal summer have been linked to Pacific La Niñas the following winter. Earlier studies have explained the appearance of the Atlantic-Pacific teleconnection with changing Atlantic Niño configurations. Here we find that the non-stationarity of this teleconnection can also be explained by changes in the ocean background state, without changing the Atlantic Niño configuration. Experiments with different atmospheric general circulation models are performed where the same Atlantic Niño pattern is prescribed to different global ocean background states. The 1975–1985 global mean sea surface temperature forces a Walker Circulation response and low-level convergence over the Maritime Continent, increasing the chance of triggering a La Niña-like event in the Pacific. These results suggest that ENSO-predictions could be improved in certain periods by considering tropical Atlantic variability.