What is the Indian Ocean Dipole?
- The IOD is often referred to as the Indian Nino. It is distinguished by the difference in temperature of ocean waters in the basin’s eastern and western regions.
- The IOD, like the Pacific’s El Nino Southern Oscillation (ENSO), consists of phases of ocean temperatures and atmospheric conditions that influence weather patterns throughout the area and beyond.
- There are two main phases of the IOD:
- Positive Phase: During this phase, the western Indian Ocean warms above normal, while the eastern half cools below average. This causes increased convection and rainfall over the western Indian Ocean and surrounding land areas such as East Africa, whereas rainfall decreases over the eastern Indian Ocean and countries such as Indonesia and Australia.
- During the negative phase, the waters in the western Indian Ocean are colder than those in the east. This causes more rainfall in the eastern Indian Ocean areas and drier weather in the west and East Africa.
Impact on the Indian Monsoon:
The Indian Ocean Dipole significantly affects the Indian Monsoon:
- Positive IOD frequently corresponds with a greater Southwest Monsoon, which brings more rain to India. This is due to the movement of warm water and associated convection towards India, which increases monsoon rainfall.
- Negative IOD can reduce the Southwest Monsoon, resulting in lower rainfall and probable drought in India. The movement of warm water away from India diminishes the essential heat and moisture to trigger monsoon rains.
Source: https://www.thehindubusinessline.com/news/positive-iod-may-re-emerge-this-year-likely-to-boost-south-west-monsoon/article68149347.ece#:~:text=A%20positive%20IOD%20can%20boost,deficit%20in%20June%2C%20experts%20said.