UPSC Prelims 1997 · General Studies

Question 30: Geography

Which one of the following factors is responsible for the change in the regular direction of the ocean currents in the Indian Ocean?

aIndian Ocean is ‘half an ocean’

bIndian Ocean has monsoon drift

cIndian Ocean is a land-locked ocean

dIndian Ocean has greater variation in salinity

AnswerThe answer is (b).

The currents of the northern Indian Ocean do not keep a steady circulation like those of the Atlantic and Pacific; they reverse with the seasons. In summer the south-west monsoon drives surface water eastward, and in winter the north-east monsoon drives it westward. This monsoon drift is why the regular direction changes. Remember: monsoon wind reversal means current reversal.

Why each option is right or wrong

(a) Being closed to the north by land limits its extent, but it does not explain the seasonal reversal.
(b) Right: the monsoon drift reverses the currents with the seasons.
(c) The Indian Ocean is open to the south and joined to the Atlantic and Pacific, so it is not land-locked.
(d) Salinity differences do not reverse currents with the seasons.

Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 1997, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.