With reference to Ocean Mean Temperature (OMT), which of the following statements is/are correct?
- OMT is measured upto a depth of 26 degree Celsius isotherm which is 129 metres 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.
Select the correct answer using the code given below:
- 1 only
- 2 only
- Both 1 and 2
- Neither 1 nor 2
Explanation
- Ocean Mean Temperature (OMT) is an important parameter in oceanography and climate science, reflecting the average temperature of the ocean to a certain depth. It provides critical insights into climatic events like monsoon patterns.
Statement 1 is incorrect
- Sea Surface Temperature (SST), which is confined to the top few millimetres of the ocean and is heavily influenced by factors like strong winds, evaporation, and thick clouds, OMT is measured down to the depth of the 26-degree Celsius isotherm. This depth provides a more stable and consistent measure of ocean temperature, with less spatial variability. The 26-degree Celsius isotherm is typically found at depths ranging from 50 to 100 meters. In the Southwestern Indian Ocean during January to March, the average depth of the 26-degree Celsius isotherm is 59 meters.
Statement 2 is correct
- Sea surface temperature (SST) is routinely used for predicting whether the total amount of rainfall that India receives during the monsoon season will be less or more than the long-term mean of 887.5 mm.
- Scientists from Pune’s Indian Institute of Tropical Meteorology (IITM) find that ocean mean temperature (OMT) that has better ability to predict this than the sea surface temperature. Compared with SST which has 60% success rate of predicting the Indian summer monsoon, OMT has 80% success rate. In addition to better predictive success, the information on whether the amount of monsoon rainfall will be more or less than the long-term mean will be available by the beginning of April, two months before the southwest monsoon can set in. This is because OMT is analysed by measuring ocean thermal energy during January to March. The southwest monsoon sets in around June 1 each year in Kerala.
