- According to a paper published in the peer-reviewed Current Science journal of the Indian Academy of Sciences, the Indian summer monsoon picked up steam despite a delayed start due to a positive phase of Equatorial Indian Ocean Oscillation (EQUINOO).
- The study was published by the scientists from the Indian Institute of Science (IISc), Bengaluru, and the Hyderabad-based National Centre for Ocean Information Services.
- The study explains that the rainfall deficit in June can be attributed to the weak El Niño over the Pacific Ocean. As the El Niño dissipated in July, the EQUINOO took the driver’s seat leading to above-normal rainfall.
- As on September 9, 2019, the country has received 792mm of rainfall compared to the normal of 737 mm – or 3% more than normal – as per the India Meteorological Department (IMD).
What is EQUINOO?
- It is as a “seesaw” or an “oscillation” between enhanced cloud formation and rainfall over the western equatorial Indian Ocean (WEIO) and suppressed clouding over the eastern equatorial Indian Ocean (EEIO) west of Sumatra.
- A positive EQUINOO phase is when the surface sea temperature in WEIO is above 27.5 degree Celsius leading to enhanced clouding, which is then suppressed in the eastern equatorial Indian Ocean.
- This increased cloud formation throughout this monsoon season is responsible for the above-average rainfall over India.
