While considerable progress has been made in understanding the decadal climate variability in the Pacific and Atlantic Oceans, our knowledge of the Indian Ocean (IO) natural internal decadal variability remains limited. Through combining observational analysis and numerical experiments using a global climate model, we have identified an IO Decadal Oscillation mode (IDO) generated by IO internal processes involving ocean dynamics and air-sea coupling, with a dominant period of 8–15 years. The most pronounced IDO signals emerge and concentrate in the subtropical South IO, extending to the tropical basin. The IDO can operate independently of forcings from outside the basin, exerting active influences on global climate. Our finding provides an additional source of decadal climate predictability.

Indian Ocean,Decadal variability,air-sea interaction