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

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

2. 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.

Select the correct answer using the code given below:

The correct answer is option 2.

Key Points

• ​Depth of the 26°C Isotherm:
  • The depth of the 26°C isotherm, which represents the Ocean Mean Temperature (OMT), is generally found between 50-100 meters, not 129 meters.
  • During January-March, the mean depth of the 26°C isotherm in the southwestern Indian Ocean is approximately 59 meters.
  • Hence, statement 1 is not correct.
• OMT and Monsoon Prediction:
  • OMT collected during January-March can be used to assess whether the monsoon rainfall will be more or less than the long-term mean.
  • It is considered a better indicator than sea surface temperature (SST) because it measures the ocean's thermal energy more effectively.
  • OMT has shown an 80% success rate in predicting the Indian summer monsoon, compared to SST's 60% success rate.
  • Hence, statement 2 is correct.

Additional Information

• Ocean Mean Temperature (OMT):
  • OMT is a more stable and consistent measure of ocean thermal energy compared to SST because it considers the temperature up to the 26°C isotherm depth.
  • Unlike SST, which only measures the top few millimeters of the ocean surface, OMT provides a better indication of the ocean's heat content, making it a reliable parameter for predicting weather patterns, including monsoons.
• Importance of OMT:
  • OMT is less influenced by short-term changes in weather conditions like strong winds, evaporation, or cloud cover.
  • This makes it a more reliable indicator for long-term climate predictions, including monsoon rainfall in India.