IOD measures differences in sea surface temperatures between the western and eastern parts of the Indian Ocean. It is basically like the El Nino weather system that develops in the Pacific Ocean. It is characterized by an irregular oscillation of sea-surface temperatures in the eastern and western Indian Ocean
Impact on weather patterns: IOD alters the wind, temperature, and rainfall patterns in the Indian Ocean region.
- Positive IOD event is known to bring floods to eastern Africa and droughts and bushfires to eastern Asia and Australia. Ex. 2020 Australian Bushfires.
- Positive IOD is known to increase the intensity of Monsoon in the Subcontinent and leads to above normal rainfall. A simultaneous occurrence of Positive IOD and El Nino balances the negative impact of El Nino on the Indian Monsoon rainfall. Ex. above normal rainfall in India in 2019.
- In contrast, Negative IOD coupled with El – Nino leads to poor Monsoon rainfall. Ex. Deficient rainfall in 1992.