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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?
Explanation
El Niño is characterized by an anomalous warming of the surface waters in the central and eastern tropical Pacific Ocean [5]. This rise in sea surface temperature is inversely related to the Indian monsoon, often leading to deficient rainfall or drought conditions [3]. During El Niño years, the Walker Circulation—a vast atmospheric loop—undergoes a significant eastward shift from its normal position [7]. In a normal year, the rising limb of this circulation is located over the Western Pacific/Indonesia, which is conducive to monsoon rainfall. However, during El Niño, the convective activity and the upward branch of the Walker Cell move toward the central and eastern Pacific [3]. This shift results in anomalous descending air motions over the Indian subcontinent, which suppresses cloud formation and weakens the south-west monsoon winds, thereby reducing overall rainfall [7].
Sources
- [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
- [5] 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
- [2] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 29: El Nino, La Nina & El Nino Modoki > 29.3. Impact of El Nino on Indian Monsoons > p. 415
- [3] Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 4: Climate of India > Possible Causes of El-Nino > p. 13
- [7] https://www.science.org/doi/10.1126/sciadv.aax4177
- [4] Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 4: Climate of India > The Southern Oscillation > p. 12