UPSC Prelims 2017 · Question 16 of 99
UPSC Prelims 2017 question on Indian Ocean Dipole (IOD)
- ExamUPSC CSE
- Year2017
- PaperGeneral Studies Paper I
- SubjectGeography
- TopicIndian Geography
- DifficultyHard
- TypeStatement
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. IOD phenomenon is characterised by a difference in sea surface temperature between tropical Western Indian Ocean and tropical Eastern Pacific Ocean.
2. An IOD phenomenon can influence an El Niño’s impact on the monsoon.
Select the correct answer using the code given below:
Show answer
Answer: B. 2 only
Verdict
The answer is 2 only. An Indian Ocean Dipole event can influence El Nino's impact on the monsoon, but the temperature difference is within the Indian Ocean, not between it and the Pacific.
Analysis
Statement 1 is INCORRECT. The Dipole is an irregular oscillation of sea surface temperatures in which the western Indian Ocean becomes alternately warmer and then cooler than the eastern part of the same ocean. The statement wrongly places the second pole in the tropical eastern Pacific. Statement 2 is CORRECT. A positive Dipole can bring good rainfall to India even in an El Nino year, while a negative one can aggravate the El Nino effect, so it modulates that influence.
Source
Indian Express explainer on the Indian Ocean Dipole and the monsoon.
How to crack it
The name contains the disproof, since Indian Ocean Dipole means two poles within the Indian Ocean, and a pole located in the Pacific would make it a different phenomenon altogether. Reading a scientific term as a description of its own geography is the quickest route here. Keep the Dipole and El Nino distinct but linked, because the examinable point is that the two interact rather than that either alone determines the monsoon.