UPSC CSE Prelims
Question 39
With reference to Ocean Mean Temperature (OMT), which of the following statements is/are correct?
- OMT is measured up to a depth of 26 °C isotherm which is 129 meters in the south-western Indian Ocean during January–March.
- OMT collected during January–March can be used in assessing whether the amount of rainfall in monsoon will be less or more than a certain long-term mean.
View correct answer and explanation
Correct answer: B
Correct Option: B (2 only)
Explanation: Ocean Mean Temperature to the 26 °C isotherm is a measure of upper-ocean heat content used to help forecast monsoon rainfall; the stated fixed 129-metre depth in the south-western Indian Ocean is not reliably correct.
Statement / Pair / Item-wise Analysis:
1. Incorrect - The 26 °C isotherm depth varies by season and ocean location; 129 m is not a universal January–March depth for the stated region.
2. Correct - Pre-monsoon upper-ocean heat content/OMT can aid prediction of seasonal rainfall anomalies.
Option-wise Analysis:
A. Incorrect-includes incorrect item 1 (The 26 °C isotherm depth varies by season and ocean location; 129 m is not a universal January–March depth for the stated region); omits correct item 2 (Pre-monsoon upper-ocean heat content/OMT can aid prediction of seasonal rainfall anomalies).
B. Correct-includes all and only valid statements/items 2.
C. Incorrect-includes incorrect item 1 (The 26 °C isotherm depth varies by season and ocean location; 129 m is not a universal January–March depth for the stated region).
D. Incorrect-omits correct item 2 (Pre-monsoon upper-ocean heat content/OMT can aid prediction of seasonal rainfall anomalies).
Review note: Specific isotherm-depth geography should be checked against the original oceanographic dataset.