ENSO-IOD Inter-Basin Connection Is Controlled by the Atlantic Multidecadal Oscillation

The interactions between El Nino-Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) are known to have great implications for global climate variability and seasonal climate predictions. Observational analysis suggests that the ENSO-IOD inter-basin connection is time-varying and related to the Atlantic Multidecadal Oscillation (AMO) with weakened ENSO-IOD relationship corresponding to AMO warm phases. A suite of Atlantic pacemaker simulations successfully reproduces the decadal fluctuations in ENSO-IOD relationship and its link to the AMO. The warm sea surface temperature (SST) anomalies associated with the AMO drive a series of Indo-Pacific mean climate changes through tropical-wide teleconnections, including the La Nina-like mean SST cooling over the central Pacific and the deepening of mean thermocline depth in the eastern Indian Ocean. By modulating ocean-atmosphere feedback strength, those mean state changes decrease both ENSO amplitude and the Indian Ocean sensitivity to ENSO forcing, therefore decoupling the IOD from ENSO.

Automated summary

The interactions between El Nino-Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) have significant implications for global climate variability and seasonal climate predictions. Observational analysis suggests that the relationship between ENSO and IOD in different basins is time-varying and related to the Atlantic Multidecadal Oscillation (AMO), with a weakened relationship during AMO warm phases. Atlantic pacemaker simulations successfully reproduce the decadal fluctuations in the ENSO-IOD relationship and its connection to the AMO. The warm sea surface temperature (SST) anomalies associated with the AMO drive climate changes in the Indo-Pacific region, including cooling of the central Pacific and deepening of the thermocline in the eastern Indian Ocean, which decouples the IOD from ENSO by modulating ocean-atmosphere feedback.