Positive Indian Ocean dipole (IOD) likely to boost southwest monsoon this year.

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  • A positive IOD also known as Indian Nino can boost the performance of India’s southwest monsoon, depending on when it develops.
  • Australian national weather agency Bureau of Meteorology (BoM) indicates a positive IOD is developing earlier than usual event. 
  • According to BoM the Indian Ocean Dipole (IOD) index for the week ending April 28, 2024, was +0.68 °C, above the positive IOD threshold (+0.40 °C).
  • IOD shows seven consecutive weeks above the positive IOD threshold. Typically, a positive IOD event is considered underway once the IOD index is sustained above +0.40 °C for about 8 weeks.
  • It is the first time since 1960 that the event (IOD) is recurring for a second consecutive year in 2024.
  • According to Weather zone if a tropical cyclone develops in the Bay of Bengal during April or May, there is a very high likelihood that a positive IOD event will occur that year.
  • India Meteorological Department (IMD) has predicted a higher-than-normal rainfall during the south-west monsoon.

What is Indian Ocean dipole (IOD)?

It is a climate pattern affecting the Indian Ocean. During a positive phase, warm waters are pushed to the Western part of the Indian Ocean, while cold deep waters are brought up to the surface in the Eastern Indian Ocean. This pattern is reversed during the negative phase of the IOD.                                 

Impact of Indian Ocean Dipole

  • The IOD is less powerful than El Niño and hence during such an event, the IOD’s impact is limited.
  • The development of IOD will likely to boost the Indian agriculture sector, as La Nina is predicted to emerge during June-August this year. 
  • A positive IOD can help rainfall in the Indian subcontinent and along the African coastline, while reducing rainfall in Australia, south-east Asia, and Indonesia.  
  • For examples in 2019, IOD stood out as one of the strongest on record. This event prolonged the Indian monsoon season, pushing it into October. 

Conversely, for Australia, a positive IOD event typically correlates with reduced rainfall from October to December, delayed monsoon onset, and diminished tropical cyclone activity.

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