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?
- 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.
- 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