2017 GS Paper I, all questions

UPSC Prelims 2017 · GS Paper I

Question 66: Geography

With reference to ‘Indian Ocean Dipole (IOD)’ sometimes mentioned in the news while forecasting Indian monsoon, which of the following statements is/are correct ?

  1. 1.IOD phenomenon is characterised by a difference in sea surface temperature between tropical Western Indian Ocean and tropical Eastern Pacific Ocean.
  2. 2.An IOD phenomenon can influence an El Nino’s impact on the monsoon.

Select the correct answer using the code given below :

a1 only
b2 only
cBoth 1 and 2
dNeither 1 nor 2

AnswerUPSC’s answer is (b).

The Indian Ocean Dipole is a difference in sea surface temperature between the tropical western Indian Ocean and the tropical south-eastern Indian Ocean, near Indonesia, so it is not a difference with the eastern Pacific and Statement 1 is wrong. A positive IOD, with warmer water in the west, brings more rain to India and can offset the damage of an El Nino to the monsoon, so Statement 2 is right. Remember: IOD is within the Indian Ocean; it can modify the El Nino effect.

  • 1. The IOD is a temperature difference across the Indian Ocean, not with the eastern Pacific.
  • 2. A positive IOD can offset the effect of El Nino on the monsoon.

How you could have got this

  1. If you were sure statement 1 is not correct, (a) and (c) go: each of them includes 1.

    What you needed to know: The IOD is a temperature difference across the Indian Ocean, not with the eastern Pacific.

  2. Then, if you were sure statement 2 is correct, (d) goes: it leaves 2 out.

    What you needed to know: A positive IOD can offset the effect of El Nino on the monsoon.

Only (b) is left. This one needs every statement.

Which options go is worked out from UPSC’s key and the options, not by a model.

Why each option is right or wrong
  • (a) Wrong: the IOD is not a contrast with the eastern Pacific.
  • (b) Right: only Statement 2, about IOD influencing El Nino's impact, is correct.
  • (c) Wrong: statement 1 is false.
  • (d) Wrong: statement 2 is correct.

Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2017, General Studies Paper I, Series A. The paper on upsc.gov.in.