El Nino

El Nino

Context:

Recent study reveals declining El Niño influence on Central India’s monsoon patterns since 1981, with only 10% of droughts or excess rains attributed to ENSO fluctuations.

About El Nino:

  • “El Niño” means “little boy” or “Christ child” in Spanish.
  • Occurs due to warm sea surface temperatures in central and east-central Equatorial Pacific.
  • Linked to ocean-atmosphere climate interaction.
  • Characterized by high pressure in the western Pacific.
  • Typically observed in December, leading to the name.
  • Adversely affects Indian monsoons and agricultural patterns.

El Niño Affects India:

  • Normal Pressure Distribution:
    • Higher pressure along the coast of Peru (South America).
    • Lower pressure in the Indian Ocean due to warmer waters.
    • Lower pressure over the Indian landmass.
  • Impact of El Niño:
    • Warm water off the Peruvian coast due to El Niño.
    • Disruption of normal trade winds or their reversal.
    • Moisture-laden winds shift towards Peru from the western Pacific.
    • Resulting in heavy rains in Peru during El Niño years.
  • Consequences for India:
    • Loss of normal monsoon rains in the Indian subcontinent.
    • Moisture-laden winds do not reach Indian landmass.
    • Reduced rainfall leads to drought conditions.
    • Agricultural productivity suffers due to water scarcity.

La Nina:

  • “La Niña” means “little girl” in Spanish, also known as “El Viejo” or “cold event.”
  • Generally, occurs every 4-5 years, less frequent than El Niño.
  • Eastern Pacific water temperatures become colder than usual.
  • Strong high pressure over the eastern equatorial Pacific.
  • Low pressure in the Western Pacific and off Asia.
  • Regional Impacts:
    • Drought in Peru and Ecuador.
    • Heavy floods in Australia.
    • High temperatures in Western Pacific, Indian Ocean, and off Somalia.
    • Good monsoon rains in India due to altered pressure and wind patterns.
  • Indian Monsoon: La Niña is generally favourable for the Indian monsoon, leading to good rainfall.

Source: The Hindu


Previous Year Question

La Nina is suspected to have caused recent floods in Australia. How is La Nina different from EI Nino?

  1. La Nina is characterized by un­usually cold ocean temperature in equatorial Indian ocean whereas EI Nino is characterized by unusually warm ocean temperature in the equatorial Pacific Ocean.
  2. EI Nino has adverse effect on south­west monsoon of India, but La Nina has no effect on monsoon climate.

Which of the statements given above is/are correct?

[UPSC Civil Services Exam – 2012 Prelims]

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

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