With reference to Ocean Mean Temperature (OMT), which of the following statements is/ are correct?

OMT is measured up to a depth of 26℃ isotherm which is 129 meters in the south- western Indian Ocean during January-

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.

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Question

With reference to Ocean Mean Temperature (OMT), which of the following statements is/ are correct?

OMT is measured up to a depth of 26℃ isotherm which is 129 meters in the south- western Indian Ocean during January-
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.

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Accepted Answer

2 only Quick Verdict: Statement 1 is incorrect because the mean depth of the 26°C isotherm in the designated region is 59 meters, not 129 meters. Statement 2 is correct because OMT has proven to be a highly accurate predictor for the Indian summer monsoon. Thematic Discussion: Ocean Mean Temperature (OMT) vs. Sea Surface Temperature (SST) Historically, meteorologists relied on Sea Surface Temperature (SST) to predict the behavior of the Indian southwest monsoon. However, according to report (1st September 2018) in the science section of The Hindu, the Indian Institute of Tropical Meteorology (IITM), Pune, published a research paper revealing that Ocean Mean Temperature (OMT) is a far superior predictive tool. The Depth Metric (Statement 1 - Incorrect): OMT is calculated by measuring the ocean's thermal energy down to the depth of the 26°C isotherm (a line connecting points of equal temperature). While this depth fluctuates globally between 50 and 100 meters, its mean depth in the Southwestern Indian Ocean during the critical January–March window is 59 meters, not the 129 meters claimed in the question. Predictive Accuracy (Statement 2 - Correct): Variations in the upper ocean’s thermal energy are a massive driving force behind the summer monsoon. Using OMT data collected during the January-March season, IITM was able to correctly predict monsoon rainfall volumes with an 80% success rate, significantly outperforming traditional SST models. Why is OMT a better predictor than SST? Feature Sea Surface Temperature (SST) Ocean Mean Temperature (OMT) Measurement Depth Restricted to the top few millimeters of the ocean. Measured down to the 26°C isotherm (approx. 50-100 meters deep). Stability Highly prone to rapid, daily fluctuations caused by surface winds, evaporation, and thick cloud cover. Highly stable and consistent; represents the actual heat energy stored in the upper ocean layers. Predictive Success Rate 60% success rate (correct in 15 out of 25 years studied). 80% success rate (correct in 20 out of 25 years studied). (Note: The 26°C mark is critical in meteorology because surface waters generally need to be at or above 26°C-26.5°C to generate enough thermal energy to sustain deep convection, storm formation, and monsoon winds).