Indian Ocean Dipole

May 9, 2024

Recently, two Australian weather agencies have said that Positive Indian Ocean Dipole (IOD) or Indian Nino in the Indian Ocean, may re-emerge for the second consecutive year in the latter half of 2024.

About Indian Ocean Dipole:

It is sometime referred to as the Indian Nino, is a similar phenomenon, playing out in the relatively smaller area of the Indian Ocean between the Indonesian and Malaysian coastline in the east and the African coastline near Somalia in the west.
A ‘positive IOD’ — or simply ‘IOD’ — is associated with cooler than normal sea-surface temperatures (SST) in the eastern equatorial Indian Ocean and warmer than normal sea-surface temperatures in the western tropical Indian Ocean.
The opposite phenomenon is called a ‘negative IOD’, and is characterised by warmer than normal SSTs in the eastern equatorial Indian Ocean and cooler than normal SSTs in the western tropical Indian Ocean.
A positive IOD event is often seen developing at times of an El Nino, while a negative IOD is sometimes associated with La Nina.
Impacts
- A positive IOD helps rainfall along the African coastline and also over the Indian sub-continent while suppressing rainfall over Indonesia, southeast Asia and Australia. The impacts are opposite during a negative IOD event.
- The IOD was identified as an independent system only in 1999.