The ISO Events in the Winter of 2007

The intraseasonal oscillation (ISO) events that occurred from November 2007 to February 2008 in the tropical Indian Ocean region were investigated by analyzing observational oceanic and atmospheric datasets. The results reveal that two ISO events were generated and developed from November 2007 to February 2008 in the tropical area of the Indian Ocean, which both originated from the southern African continent and propagated along a northeastward direction and finally penetrated into the equatorial eastern Indian Ocean. Compared with the general winter MJO event, which tended to travel along the equator from the western Indian Ocean into the western Pacific, the ISO of winter 2007 propagated not only along the equator into the eastern part of the Indian Ocean but was also transported northward into the subtropical region in the eastern Indian Ocean, which is more similar to the behavior of traditional summer ISO events.