The Atlantic Niño is significantly influenced by the Indian Ocean Dipole (IOD), but their relationship has exhibited obvious interdecadal variations over the past decades. With a focus on the possible causes of this non-stationarity, we find that the IOD alone cannot fully explain these interdecadal variations. While accounting for El Niño–Southern Oscillation (ENSO) weakens the IOD–Atlantic Niño relationship, interdecadal fluctuations persist. Observational analyses and numerical experiments with CESM1.2.2 demonstrate that Atlantic preconditions play a crucial role in shaping the IOD–Atlantic Niño relationship. Cold sea surface temperature (SST) anomalies in the central–eastern equatorial Atlantic during boreal autumn, characteristic of periods with a weak IOD–Atlantic Niño relationship, hinder subsequent Atlantic Niño development. Conversely, neutral Atlantic preconditions, prevalent during periods with a strong relationship, facilitate IOD-induced Atlantic Niño events. Atlantic preconditions thus contribute to modulating the IOD–Atlantic Niño teleconnection, highlighting the complexity of the trans-basin climate interaction.
 

Atlantic Niño,Indian Ocean Dipole (IOD),interdecadal variations,ENSO,Atlantic preconditions