Sea temperature can help predict monsoon better

You may know whether to expect a year of floods or water cuts if meteorologists start observing temperatures over the sea.

You may know whether to expect a year of floods or water cuts if meteorologists start observing temperatures over the sea.

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Based on a study released on November 10, scientists from the Bangalore-based Indian Institute of Science said weathermen would be able to predict monsoon rainfall more accurately if they monitor temperatures over the sea.

This parameter is not among the seven factors used to predict rainfall.

“Most models across the globe predicted average rainfall in the Indian region, contrary to what happened,” said Sulochna Gadgil, honorary professor at the Centre of Atmospheric and Oceanic Sciences in IISc and co-author of a research paper on this year’s monsoon.

High temperature over the Bay of Bengal from June to September usually ensures good rainfall.

But this year, the temperature over the Indian Ocean was higher than that over the Bay, drawing monsoon winds away from India and not allowing a low pressure situation to settle over the Bay for long.

This rare weather pattern weakened the journey of the southwest monsoon, which had reached the Kerala coast before schedule, leading to a 54 per cent deficit in rainfall in June, the second worst showing since 1926, according to the study.

The rain deficit has led to a 15 per cent water cut in Mumbai.

In 1995, which saw a 24 per cent rain deficit, temperatures over the Indian Ocean exceeded those over the Bay of Bengal.

“Sea surface temperatures influence 60 to 70 per cent of monsoon activity, so monitoring them will help,” said Pradhan Parth Sarthy, climate scientist with Delhi-based The Energy and Resources Institute.

“But to what extent is not yet clear because monsoon patterns have been changing every year.”