Here is Question No. 66 a part of our series on UPSC Prelims 2017
Q66. With reference to ‘Indian Ocean Dipole (IOD)’. sometimes mentioned in the news while forecasting the Indian monsoon, which of the following statements is/are correct?
- IOD phenomenon is characterised by a the difference in sea surface temperature between the tropical Western Indian Ocean and tropical Eastern Pacific Ocean.
- An IOD phenomenon can influence an El Nino’s impact on the monsoon.
Select the correct answer using the code given below:
a) 1 only
b) 2 only
c) Both 1 and 2
d) Neither 1 nor 2
The correct answer is 2 only.
- Indian Ocean Dipole (IOD)
- The difference in sea surface temperature between two poles or areas (hence a dipole) in the Indian Ocean, namely an eastern pole in the eastern Indian Ocean south of Indonesia and a western pole in the Arabian Sea (western Indian Ocean). Hence, statement 1 is incorrect.
- The IOD influences the climate of countries surrounding the Indian Ocean Basin, such as India and Australia, and is a significant contributor to rainfall variability in this region.
- The IOD is a coupled ocean-atmosphere phenomenon, similar to El Nino-Southern Oscillation (ENSO), but occurring in the equatorial Indian Ocean.
- The IOD is thought to be linked to ENSO events via an extension of the Walker Circulation to the west and associated Indonesian throughflow (the flow of warm tropical ocean water from the Pacific into the Indian Ocean).
- Hence, negative IOD events are frequently associated with La Nina, while positive events are associated with El Nino. Hence, statement 2 is correct.
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