With reference to Ocean Mean Temperature (OMT)
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 southwestern 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
Answer: B
Explanation
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.
Now, scientists from Pune’s Indian Institute of Tropical Meteorology (IITM) find that Ocean Mean Temperature (OMT) 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.
OMT is analysed by measuring the ocean thermal energy during the period from January to March. Using OMT data, scientists are able to predict with 80% probability the monsoon of any year. Hence, statement 2 is correct.
SST is restricted to a few millimetres of the top ocean layer, whereas OMT which is measured up to a depth of 26 degree C isotherm, is more stable and consistent, and the spatial spread is also less. The 26 degree C isotherm is seen at depths varying from 50-100 metres. During January–March, the mean 26 degree C isotherm depth in the Southwestern Indian Ocean is 59 metres. Hence, statement 1 is not correct.
- Exam Year: 2020