ENSO Current Affairs - 2020

Facts Box: Effects of El-Nino, Equinod and IOD on Indian Monsoon, 2019

The ongoing frenetic of the North-East Monsoon in the Peninsular India were supported by the same factors that propelled the South-West monsoon. The Indian monsoon of 2019 saw a neutral Pacific (neither El Nino nor La Nina), a positive Indian Ocean Dipole (IOD) and a positive Equatorial Indian Ocean Oscillation (EQUINOO).

El nino

  •  The variation in sea surface temperature drives the Indian Ocean and the Pacific phenomena and thereby Indian Monsoon.
  • The El Nino is a phenomenon in the equatorial Pacific where the temperature rises over a threshold of 0.5 degree Celsius. During El Nino the Equatorial East Pacific warms up relative to the west and has adverse impact on Indian monsoon.
  • The monsoon winds and rains are strong during La Nina and weak during El Nino. La Nina years bring heavy rains and El Nino years are dry.
  • Between 1950 and 2012, there were 16 La Nina years with monsoon rains ending up above or around average every time. Also, there were 14 other occasions. The 2002 was the driest monsoons in all these years when El Nino occured.
  • The weak El Nino in the Pacific Ocean this year is one of the reasons for rainfall deficit in the month of June.

IOD

In a positive IOD, the western basin of the Indian Ocean warms up creating a low pressure. This rises warm air clouds to set up storms and heavy rains in the South and South east Asia. A positive IOD aids in Indian monsoon. 2019 Monsoon witnessed a positive IOD

EQUINOD

The positive EQUINOD translates more or less positive IOD. The Positive EQUINOD aids in North East Monsoon. 2019 monsoon witnessed a positive EQUINOD.

IMD confirms weak El Nino Conditions

India Meteorological Department (IMD) has finally declared that weak El Nino conditions are prevalent in the equatorial Pacific Ocean. IMD predicts that these conditions are likely to persist in the early part of the summer season and likely to weaken thereafter.

The initial impact of a weak El Nino can already be seen with the rising temperatures and heat waves across the country.

Till Mid March IMD was maintaining that “warm ENSO neutral conditions are prevailing over equatorial Pacific Ocean” and that they are likely to remain near to the El Nino threshold value during the next two months. The current declaration marks the departure from its earlier predictions.

It is said that the prediction for El Nino has come after a delay since weather agencies in other countries had declared weak El Nino conditions at the beginning of 2019 viz.

  • Japan’s Meteorological Agency (JMA) in January had said that El Nino conditions were prevailing and that there was 80 per cent chance of an El Nino phenomenon staying till spring season of 2019.
  • Climate Prediction Centre (CPC) of the National Weather Service in the United States of America also concluded that weak El Nino conditions had formed in the equatorial Pacific Ocean around the same time as Japan.

Further an update by the CPC on March 14, 2019 states that “weak El Niño conditions are likely to continue through the Northern Hemisphere spring 2019 with an 80 per cent probability and summer with a 60 per cent probability”.