Indian Ocean Dipole

The Indian Ocean Dipole is an irregular climate pattern defined by sea-surface temperature contrasts between the western and eastern tropical Indian Ocean. Its phases shift rainfall and atmospheric circulation around the Indian Ocean.

Dipole Mode Index: A measure of the sea-surface temperature difference between the western and southeastern tropical Indian Ocean. This index tracks the temperature contrast used to identify dipole phases.
1997–1998 Indian Ocean Dipole: A strong positive Indian Ocean Dipole event that peaked in 1997 and affected rainfall across the Indian Ocean region. It is a prominent example of a positive event, coinciding with the 1997–1998 El Niño.
El Niño–Southern Oscillation: A coupled tropical Pacific climate pattern that alternates between El Niño, La Niña, and neutral conditions. ENSO can influence Indian Ocean dipole development, though the patterns are distinct.
Seasonal climate prediction: Forecasting average climate conditions for months ahead using observations and climate models. Dipole monitoring contributes information about likely seasonal rainfall patterns.
Walker circulation: An atmospheric circulation pattern with rising air over warm regions and sinking air over cooler regions across the tropics. The dipole shifts this east–west circulation over the Indian Ocean.
2006 Indian Ocean Dipole: A strong positive Indian Ocean Dipole event that developed in 2006 and influenced rainfall around the basin. Its development illustrates that strong events can occur outside major El Niño episodes.
Indian Ocean basin-wide mode: A climate pattern in which sea-surface temperatures across much of the tropical Indian Ocean vary together. It contrasts basin-wide warming with the dipole’s east–west temperature opposition.
Climate model: A computer-based representation of the climate system that simulates interactions among its components. Models test whether the dipole’s coupled ocean and atmosphere processes are represented accurately.
Ocean-atmosphere interaction: The exchange of heat, moisture, and momentum between the ocean and atmosphere. Coupled feedbacks between sea and air sustain and amplify dipole events.
2019 Indian Ocean Dipole: A strong positive Indian Ocean Dipole event in 2019 associated with exceptional rainfall contrasts around the Indian Ocean. The event brought severe flooding in East Africa and unusually dry conditions in parts of Australia.

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