El Niño: Three of four criteria have been met, says Australian Weather Agency

  • June 21, 2023
  • Posted by: OptimizeIAS Team
  • Category: DPN Topics
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El Niño: Three of four criteria have been met, says Australian Weather Agency

Subject: Geography

Section: Physical geography (Climatology)

Context:

  • The Australian Bureau of Meteorology has said that three of the four criteria for the development of El Niño have been met, increasing the chances of the warm weather event setting in this year.

Details:

  • El Niño conditions, which are abnormal warming of the sea surface temperatures of the Pacific Ocean leading to drought and deficient rainfall in Asia — particularly India, had developed by mid-June.
  • The previously ENSO-neutral conditions in the central-eastern equatorial Pacific had transitioned to warm El Niño-like conditions.
  • The key oceanic and atmospheric variables are consistent with the onset of El Niño and signalled the onset of the warm phase of the ENSO.

El-Nino event:

  • El Nino refers to the large-scale ocean-atmosphere climate interaction linked to periodic warming in sea surface temperatures across the central and east-central Equatorial Pacific. It is associated with high pressure in the western Pacific. El Nino adversely impacts the Indian monsoons and hence, agriculture in India.

When criteria were met in the past:

  • When El Niño alert criteria have been met in the past, an El Niño event has developed around 70 per cent of the time.
  • There is an 80 per cent chance of El Niño conditions developing by the end of August.
  • Criteria met are:
    • The central and eastern Pacific sea surface temperatures have warmed to El Niño thresholds.
    • The trade winds have been weaker than average in the western or central equatorial Pacific Ocean during any two of the last three months, while the two-month average Southern Oscillation Index has been 0.7 or lower.
    • The sustained warming to at least 0.8°C above average in the NINO3 or NINO3.4 regions of the Pacific Ocean by the late winter or spring.

Impact on Indian monsoon:

  • Despite El Niño being forecast this year, the India Meteorological Department (IMD) has said the southwest monsoon, the key to agricultural production, will be normal.
  • The southwest monsoon, which accounts for 76 per cent of the country’s total annual rainfall, set in late by a week this year. Data from IMD show that rainfall in the current monsoon is 33 per cent deficient as of June 19.
El Niño: Three of four criteria have been met Geography