Indian Ocean Dipole

About Indian Ocean Dipole: 

• It is sometimes 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.

Q1: What is El Nino?

A warming of the ocean surface, or above-average sea surface temperatures (SST), in the central and eastern tropical Pacific Ocean. It is associated with lower than normal monsoon rainfall in India.

Source: Positive IOD may re-emerge this year, likely to boost south-west monsoon