For the past 150-200 years, the Bay of Bengal has given birth to four times more cyclones than the Arabian Sea. But this may soon change, thanks to global warming.
“ For every four cyclones in the Bay of Bengal, there is one in the Arabian Sea. We have data for more than 150-200 years. When you look at this data and calculate, a ratio of 1 is to 4 is established,” says KS Hosalikar, Head SID, Climate Research & Services, Pune India Meteorological Department said.
Explaining the reason for this major difference between the number of cyclonic storms on the eastern and western shores of India, KS Hosalikar said that there are multiple factors that affect the creation of a storm in the sea.
“There are various reasons for it, including the geographical location, the sea surface temperature (SST, as well as salinity of the sea. All of these play an important role,” Hosalikar said.
But this ratio may soon change. A study by The Indian Institute of Tropical Meteorology has shown that both the frequency and intensity of cyclones in the Arabian Sea are on the rise. The experts believe the key reason is a rise in the ocean temperature.
“The ideal sea temperature or SST for the formation of cyclones is 28.5 degrees Celsius. At the usual 28 degrees SST, the Bay of Bengal is categorised as a warm pool region. Cyclones draw their energy from the warm pool regions,” Roxy Koll of The Indian Institute of Tropical Meteorology said.
“Traditionally, the Arabian Sea is a lot cooler than the Bay of Bengal. But now the Arabian Sea is also becoming a warm pool region because of the additional heat supplied by global warming,” he said.
WHY BAY OF BENGAL CREATES SIGNIFICANTLY MORE CYCLONES
Apart from being a warm pool region, the Bay of Bengal is slightly more landlocked with South East Asian countries surrounding it, compared to the Arabian Sea, which is more expansive and this also leads to an increase in salinity of the seawater.
According to experts, the Bay of Bengal also gets many remnants of the typhoons in the Pacific Ocean. They come as a low-pressure area into the Bay of Bengal and grow into cyclones due to ideal conditions.
MORE DATA REQUIRED FOR BETTER RESEARCH
There are various buoys that are set up in the sea across the Bay of Bengal as well as the Arabian Sea which help collect data on temperature, pressure, wind speed, etc. This data helps the scientists conduct their research but they say that there is a need to have a larger network of buoys in the sea to get better and more accurate data.
Hosalikar said there is a need to study the ‘rapid intensification of the system’. The formation of a cyclone begins from a ‘low pressure’ to a ‘well-marked low pressure’ to a ‘depression’ to a ‘deep depression’ to a ‘cyclonic storm’ then a ‘sever cyclone’ to a ‘very severe cyclone and then an ‘extremely severe cyclone’ and lastly, a ‘super cyclone’.
Scientists say that earlier the formation of cyclones used to take a long time between different phases. But now, the intensity of a cyclone can change overnight.
“These cyclones are intensifying into a super cyclone or an extremely severe cyclone in less than 24 hours. So, it may be a weak cyclone when you go to sleep and a severe cyclone at your doorstep when you wake up. That gives us less time to respond,” Roxy Koll said.
