Discovered by Dr. Toshio Yamagata (Director of Climate Variations Research Program), Dr. Saji Hameed (currently senior researcher of APEC Climate Center in Pusan) and other research staff in 1999 and reported in Nature. The event is similar to El Nino in the tropical Pacific Ocean. Seawater temperature drops in eastern Indian Ocean (off Java), rises in middle to western Indian Ocean (off Kenya). Along with this ocean climate change, east wind strengthens above the equator. This IOD normally develop in May or June, at peak in October and diminish in December. It is clear that this event brings drought in Indonesia and eastern Australia; on the other hand it brings floods in eastern African countries such as Kenya. And it greatly affect summer monsoon, brings the heavy rain northern India to Indochina and southern China, brings extreme heat in Far East Asia and from western Japan to Okinawa Japan. It is reported as a study result that the event relates closely to the extreme heat in Mediterranean countries.