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Q74 (CDS-I/2022) Geography › World Physical Geography › Ocean-atmosphere oscillations Answer Verified

Which one of the following is not a resultant of the El Nino effect ?

Result
Your answer: —  Â·  Correct: B
Explanation

El Niño is a complex climatic phenomenon characterized by the warming of surface waters in the eastern equatorial Pacific Ocean [3]. It results in the distortion of equatorial atmospheric circulation, specifically the Walker Cell, where the ascending branch shifts eastward [4]. This shift causes trade winds to weaken or even reverse their direction [4]. Consequently, the flow of South-East Trade Winds towards the Indian Ocean is disrupted or weakened, rather than being a resultant flow [5]. The warming leads to irregularities in sea water evaporation and a deepening of the thermocline, which suppresses the upwelling of nutrient-rich cold water [6]. This lack of nutrients causes a significant reduction in phytoplankton (plankton) levels, which subsequently reduces fish populations, severely impacting marine ecosystems and local fisheries [7]. Therefore, option 2 is the incorrect statement regarding El Niño's effects.

Sources

  1. [1] 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
  2. [3] Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 4: Climate of India > Possible Causes of El-Nino > p. 13
  3. [4] 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
  4. [5] https://oceanservice.noaa.gov/facts/ninonina.html
  5. [6] https://www.pmel.noaa.gov/gtmba/files/PDF/pubs/ElNinoLaNina.pdf
  6. [7] https://www.nature.com/scitable/knowledge/library/el-nino-s-grip-on-climate-25816069/
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SIMILAR QUESTIONS

NDA-II · 2013 · Q53 Relevance score: 4.38

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 :

NDA-II · 2012 · Q88 Relevance score: 0.70

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?

CDS-I · 2010 · Q93 Relevance score: 0.21

Which one of the following is not associated with monsoon climate in India ?

IAS · 2011 · Q52 Relevance score: -0.28

La Nina is suspected to have caused recent floods in Australia. How is La Nina different from EI Nino? 1. La Nia is characterised by unusually cold ocean temperature in equatorial Indian Ocean whereas EI Nino is characterised by unusually warm ocean temperature in the equatorial Pacific Ocean. 2. El 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/ correct?

NDA-II · 2010 · Q2 Relevance score: -0.34

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