BHUBANESWAR: Frequency of cyclone formation over Bay of Bengal and Arabian Sea has not seen a rise but the two regions have witnessed above normal cyclogenesis in last two years. This was informed by Minister for Science and Technology and Earth Sciences Dr Harsh Vardhan in a reply to an unstarred question in Lok Sabha.
Odisha has a reason to worry about cyclones forming over Bay of Bengal given the number of systems that occur annually and the recent experience with natural calamities like Fani which left behind a trail of devastation.
However, the Union Minister said that no significant increasing trend is established in frequency of cyclone occurrences over Bay of Bengal and Arabian Sea when long term data is considered.
“The recent two years have witnessed above normal cyclogenesis over these ocean basins,” he said.
Cyclogenesis is the probability of development or strengthening of an area of low pressure into a cyclone.
This year, though, more cyclones formed over Arabian Sea as compared to Bay of Bengal, said Director Bhubaneswar Meteorological Centre, HR Biswas. Bay of Bengal has a history of generating deadly systems.
Experts said warm temperatures are occurring more often and over longer periods of time which is a result of gradual warming on a global scale and resulted in a net increase in ocean temperatures. Warmer ocean temperatures allow stronger storms to form.
These conditions are exacerbated by global mechanisms including El Nino and the Indian Ocean Dipole which concentrates warm ocean waters in smaller geographic areas.
Regional Met officials said one of the reasons why tropical cyclones are more prone to form over Bay of Bengal is that its surface temperature is higher than that of the Arabian Sea.
Tropical cyclones generally need a temperature of over 26.5 degrees Celsius.
The Bay of Bengal is more conducive to this than the Arabian Sea.
According to private weather forecaster Skymet, there were 14 disturbances in 2018 out of which the number of cyclones formed was seven, while in 2019, there was a formation of nine disturbances, of which seven ended up in becoming cyclones, making this year with the highest conversion rate.
A recent check on the data reveals that the number of cyclones as well as severe cyclones in Arabian Sea as well as Bay of Bengal has increased by almost 11 per cent in the last one decade.
Moreover, the rising trend has shown more growth in the last five years with an increase of about 32 per cent, it said.