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Q2 (NDA-II/2010) Geography › World Physical Geography › Ocean-atmosphere oscillations Answer Verified

Which among the following statements characterized El Nino? I. It occurs at irregular intervals II. It carriers warmer water III. It carries less saline water IV. Its atmospheric equivalent is southern oscillation Select the correct answer using the code given below

Result
Your answer: —  Â·  Correct: D
Explanation

El Niño is a complex climatic phenomenon characterized by several distinct features. First, it occurs at irregular intervals, typically every two to seven years, rather than on a fixed schedule [t1][t2][t4]. Second, it is defined by the anomalous warming of sea surface temperatures in the central and eastern equatorial Pacific Ocean [c2][c5][t8]. Third, these warmer waters are associated with lower salinity levels; as the warm pool shifts eastward, it suppresses the upwelling of nutrient-rich, saltier deep water and is often accompanied by increased precipitation which further freshens the surface layer [t6]. Finally, the Southern Oscillation represents the atmospheric component of this system, involving shifts in air pressure between the eastern and western Pacific [c1][c5][t2]. When these oceanic and atmospheric changes occur together, they are collectively referred to as the El Niño-Southern Oscillation (ENSO) [c1][t7]. Thus, all four statements accurately characterize the phenomenon.

Sources

  1. [1] https://www.nature.com/articles/s41598-025-01809-2
  2. [2] https://education.nationalgeographic.org/resource/el-nino/
  3. [3] https://oceanservice.noaa.gov/facts/ninonina.html
  4. [4] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 8: Natural Hazards and Disaster Management > el nino (southern oscillation) and indian Monsoon > p. 54
  5. [5] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 9: Atmospheric Circulation and Weather Systems > General Atmospheric Circulation and its Effects on Oceans > p. 80
  6. [6] https://www.noaa.gov/understanding-el-nino
  7. [7] https://www.nature.com/articles/s41598-025-99511-w
  8. [8] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 29: El Nino, La Nina & El Nino Modoki > El Nino Southern Oscillation (ENSO) > p. 413
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SIMILAR QUESTIONS

CDS-II · 2011 · Q1 Relevance score: 0.64

Statement I : El Nino is a temperature rising phenomenon over the Pacific Ocean and usually causes dry mon- soon in South Asia. Statement II. : Tsunamis are usually not noticed as the massive ocean waves move silently but assume destructive form as these travel through shallow waters of continental shelves.

NDA-II · 2012 · Q88 Relevance score: -0.24

Consider the following statements regarding El Nino effect on Indian monsoon: 1. The surface temperature goes up in the Southern Pacific Ocean and there is dificient rainfall in India. 2. The Walker Circulation shifts Eastward from its normal position and reduces monsoon rainfall in India. Which of the statement(s) given above is/are correct?

NDA-II · 2013 · Q53 Relevance score: -0.55

Which of the following are the results of El Nino? 1. Reduction in the amount of planktons which further reduces the number of fish in the sea. 2. Irregularities in the evaporation of sea water. 3. Distortion of equatorial atmospheric circulation. Select the correct answer using the code given below :

CDS-II · 2011 · Q18 Relevance score: -1.57

EL Nino associated with the formation of the South West Monsoon of India is