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Equatorial Indian Ocean Oscillation (EQU

  Jun 04, 2020

Equatorial Indian Ocean Oscillation (EQUINOO)

What is EQUINOO?

Equatorial Indian Ocean Oscillation (EQUINOO) is considered to be the atmospheric component of the Indian Ocean dipole mode. EQUINOO is deļ¬ned as the oscillation between a state in which the convection/precipitation is enhanced over Western Equatorial Indian Ocean (WEIO) and suppressed over the Eastern Equatorial Indian Ocean EEIO convection/precipitation is enhanced over EEIO and that in which convection/precipitation is enhanced over EEIO and suppressed over WEIO. Although the distinguishing attribute of EQUINOO is the see-saw in the convection over EEIO and WEIO, and the monsoon–EQUINOO link is manifested as a link between the outgoing long wave radiation (OLR) anomaly over the Indian region and that over the equatorial Indian Ocean. 

The Indian summer monsoon picked up steam despite a delayed start due to a positive phase of Equatorial Indian Ocean Oscillation (EQUINOO).

  • A positive EQUINOO phase is when the surface sea temperature in WEI is above 27.5 degrees Celsius leading to enhanced clouding, which is then suppressed in the eastern equatorial Indian Ocean. The increased cloud formation throughout this monsoon season is responsible for the above-average rainfall over India. 
  • As on September 9, the country has received 792mm rainfall compared to the normal of 737 mm- or 3% more than normal - as per the India Meteorological Department. 
  • The southwest monsoon till date is normal to excess in 28 meteorological subdivisions out of the 36 subdivisions, and deficient in just 8.