UPSC Prelims Practice Questions — Why even a strong El Niño does not guarantee a poor Indian monsoon

Q1. With reference to the Indian Ocean Dipole (IOD), consider the following statements: Which of the statements given above is/are correct?

  1. A positive IOD tends to reduce rainfall over the eastern Indian Ocean and the Maritime Continent.
  2. During a negative IOD, Indonesia and Australia tend to be wetter than normal.
  3. In a positive IOD, the eastern pole of the tropical Indian Ocean off Sumatra is warmer than the western pole.
  • A. 2 and 3 only
  • B. 1 only
  • C. 1 and 2 only
  • D. 1, 2 and 3

Q2. With reference to the El Niño Southern Oscillation (ENSO), consider the following statements: Which of the statements given above are correct?

  1. In non-El Niño conditions, the easterly trade winds pile up warm surface water in the western equatorial Pacific near Indonesia.
  2. During an El Niño, the upwelling of cold water along the coast of South America intensifies.
  3. The 'Southern Oscillation' refers to the see-saw in sea-level air pressure across the tropical Pacific that accompanies the ocean changes.
  4. During a strong El Niño, the trade winds over parts of the equatorial Pacific may weaken so much that they reverse into westerlies.
  • A. 2, 3 and 4 only
  • B. 1 and 2 only
  • C. 1, 2, 3 and 4
  • D. 1, 3 and 4 only

Q3. Consider the following statements: Which of the following is correct in respect of the above statements?

  1. A positive Indian Ocean Dipole event tends to bring enhanced rainfall to equatorial East Africa.
  2. In a positive Indian Ocean Dipole, the western tropical Indian Ocean is warmer than normal, which favours stronger convection over that part of the basin.
  • A. Both Statement-I and Statement-II are correct and Statement-II explains Statement-I
  • B. Both Statement-I and Statement-II are correct, but Statement-II does not explain Statement-I
  • C. Statement-I is correct, but Statement-II is incorrect
  • D. Statement-I is incorrect, but Statement-II is correct

Q4. The India Meteorological Department classifies the all-India southwest monsoon season as 'deficient' on the basis of which one of the following?

  • A. More than half of the meteorological subdivisions recording a rainfall shortfall
  • B. Seasonal rainfall falling short of the Long Period Average by 10% or more
  • C. Seasonal rainfall over the country falling below a fixed absolute total of 75 cm
  • D. Monsoon onset over Kerala being delayed by more than a week from its normal date