Based on NCEP and GODAS monthly reanalysis data for the period 1982-2013,we explored the influence of atmospheric and oceanic processes on the SST anomaly over the equatorial Southeast Indian Ocean during Indian Ocean Dipole(IOD) events using regression analysis,composite analysis and a 2.5-layer dynamic upper-ocean model.Results show that the SST anomaly over the equatorial Southeast Indian Ocean,which plays a key role in the formation and maintenance of IOD events,has an advanced phase in comparison with that of the SST anomaly over the equatorial West Indian Ocean.The intensity of the SST anomaly over the equatorial Southeast Indian Ocean is stronger than that over the equatorial West Indian Ocean during the entire cycle of IOD events.The SST anomaly over the equatorial Southeast Indian Ocean matures in the fall,whereas over the equatorial West Indian Ocean it matures in winter.Strong moisture transport from the Arabian Sea,northeastern Indochina Peninsula,and southwestern Bay of Bengal,to the eastern Bay of Bengal,results in significantly increased rainfall over the eastern Bay of Bengal in early summer.Latent heat release because of the heavy rainfall anomaly over the eastern Bay of Bengal perhaps strengthens the local meridional circulation crossing the equatorial eastern Indian Ocean.The local meridional circulation crossing the equatorial eastern Indian Ocean may contribute to the southerly wind anomalies off the coast of Sumatra.The southerly wind anomalies off the coast of Sumatra may lead to a negative SST anomaly over the equatorial Southeast Indian Ocean through enhanced entrainment and zonal advection.Then,the rapid enhancement of southeast wind anomalies off the coast of Sumatra stimulated by the negative SST anomaly over the equatorial Southeast Indian Ocean and easterly wind anomalies in the central-eastern equatorial Indian Ocean,transport moisture from the equatorial Southeast Indian Ocean to the equatorial West Indian Ocean.This leads to less rainfall over the Bay of Bengal and equatorial Southeast Indian Ocean,and more rainfall over the West Indian Ocean.Westward-propagating warm Rossby waves south of the equator stimulated by anomalous anticyclones could lead to a warming SST anomaly over the Southwest Indian Ocean.Therefore,the southeast wind anomalies off the coast of Sumatra,because of the heavy rainfall anomaly over the eastern Bay of Bengal,through the local meridional circulation crossing the equatorial eastern Indian Ocean,leads to a negative SST anomaly over the equatorial Southeast Indian Ocean and contributes to the birth of an IOD event.