The authors have investigated the interactions of the tropical oceans on interannual timescales by conducting a series of uncoupled atmospheric and oceanic general circulation experiments and hybrid-coupled model simulations. The results illustrate the key role of the El Niño/Southern Oscillation phenomenon in generating interannual variability in all three tropical ocean basins. Sea surface temperature anomalies in the tropical Pacific force SST anomalies of the same sign in the Indian Ocean and SST anomalies of the opposite sign in the Atlantic via a changed atmospheric circulation. However, although air-sea interactions in the Indian and Atlantic Oceans are much weaker than those in the Pacific, they contribute significantly to the variability in these two regions. The role of these air-sea interactions is mainly that of an amplifier by which the ENSO-induced signals are enhanced in the ocean and atmosphere. This process is particularly important in the tropical Atlantic region. The authors in... Abstract The authors have investigated the interactions of the tropical oceans on interannual timescales by conducting a series of uncoupled atmospheric and oceanic general circulation experiments and hybrid-coupled model simulations. The results illustrate the key role of the El Niño/Southern Oscillation phenomenon in generating interannual variability in all three tropical ocean basins. Sea surface temperature anomalies in the tropical Pacific force SST anomalies of the same sign in the Indian Ocean and SST anomalies of the opposite sign in the Atlantic via a changed atmospheric circulation. However, although air-sea interactions in the Indian and Atlantic Oceans are much weaker than those in the Pacific, they contribute significantly to the variability in these two regions. The role of these air-sea interactions is mainly that of an amplifier by which the ENSO-induced signals are enhanced in the ocean and atmosphere. This process is particularly important in the tropical Atlantic region. The authors in...