Seasonal phase-locking of peak events in the eastern Indian Ocean

The sea surface temperature (SST) anomaly of the eastern Indian Ocean (EIO) exhibits cold anomalies in the boreal summer or fall during El Niño development years and warm anomalies in winter or spring following the El Niño events. There also tend to be warm anomalies in the boreal summer or fall during La Niña development years and cold anomalies in winter or spring following the La Niña events. The seasonal phase-locking of SST change in the EIO associated with El Niño/Southern Oscillation is linked to the variability of convection over the maritime continent, which induces an atmospheric Rossby wave over the EIO. Local air-sea interaction exerts different effects on SST anomalies, depending on the relationship between the Rossby wave and the mean flow related to the seasonal migration of the buffer zone, which shifts across the equator between summer and winter.