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Indian Ocean Dipole turns positive

Facts for Prelims (FFP)

 

Source: Business Line

 Context:  A report by the Australian Bureau of Meteorology said that the IOD index has risen beyond the positive threshold.

  • The IOD refers to temperature shifts in the Indian Ocean basin, impacting monsoons in India. A positive IOD event, characterized by warmer temperatures in the western basin, can enhance India’s South-West monsoon.
  • However, the IOD index must remain above the threshold for a sustained period to officially declare a positive event.
  • The positive IOD event tends to benefit the Southwest monsoon.

 

For Australia, a positive IOD event often leads to low rainfall between October and December, delayed monsoon onset, and reduced tropical cyclone activity.

 

About IOD: 

IOD stands for the Indian Ocean Dipole. It refers to a climate phenomenon characterized by the difference in sea surface temperatures between the western and eastern parts of the Indian Ocean.

 

There are two phases of the Indian Ocean Dipole:

Positive IOD: In this phase, the western Indian Ocean becomes warmer than the eastern part. This leads to increased convection and rainfall in the western Indian Ocean region, including parts of East Africa and the Arabian Peninsula, while causing drier conditions in the eastern Indian Ocean, including Australia and Indonesia.

Negative IOD: In this phase, the eastern Indian Ocean becomes warmer than the western part. This leads to higher rainfall and cooler conditions in the eastern Indian Ocean region, including Australia and Indonesia, while causing drier conditions in the western Indian Ocean region.