ENSO Current Affairs - 2019
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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”.
Weather scientists have predicted normal monsoon in June-September 2018 monsoon season as prevailing conditions as well as neutral ENSO were favourable for good monsoon rainfall. India receives 89 cm of rainfall during four-month monsoon season, which is almost 75% of its annual rainfall. In 2017 monsoon season, country as whole had received rainfall that was 95% of its long-period average.
The most important favourable condition for good monsoon is near-neutral to neutral ENSO (El Nino Southern Oscillation) in equatorial Pacific Ocean, off coast of South America. Global climate models are showing near-neutral conditions prevailing in Pacific Ocean and it will remain this way through most of the year.
Moreover, La Niña conditions are present and equatorial sea surface temperatures (SSTs) are below average across central and eastern Pacific Ocean. The transition from La Niña to ENSO-neutral is most likely during March-May season, with neutral conditions likely to continue into second half of year. SST anomalies in eastern tropical pacific are ENSO-neutral during coming summer and hence normal monsoon is expected this year.
ENSO (El Nino Southern Oscillation)
ENSO refers to anomalies in SSTs in Pacific Ocean off coast of South America which has sometimes been observed to have near-decisive impact on monsoon rainfall. In El Nino, a warmer than usual SST is observed in Pacific Ocean off coast of South America . This condition is associated with suppressed monsoon rainfall in India. La Nina is opposite ENSO and is more favourable for monsoon. It is known to help monsoon rainfall in India. When anomalies (deviations from usual SST in the Pacific Ocean) are too small or absent, monsoon rainfall over India is normal.