Visakhapatnam: People living in towns and cities on the east coast along the Bay of Bengal have reason to cheer. The Bay of Bengal is warming at a lesser rate than the Arabian Sea and Indian Ocean, which may lead to lesser temperatures in the towns on the east coast over a period of time.
Temperatures will not rise as fast as on the west coast along the Bay of Bengal.
Globally, warming of the Atlantic and Pacific oceans at a rapid rate has set alarm bells ringing. However, ocean scientists were surprised to see the decline in warming in Bay of Bengal.
A study conducted by the scientists of the (NIO), based on 52 years of data, pointed out that after 1995 there has been slowdown in Sea Surface Temperature (SST) warming.
The rising trend in the sea surface temperature is due to increasing atmospheric CO2 concentration. The change is attributed to the increase in occurrence of cyclonic systems in the Bay of Bengal after 1995 leading to an increase in the mixing of cold subsurface waters with warm surface waters.
The slowdown in the SST rise, in the post-1995 period, is due to the increase in the number of depressions, cyclones and severe cyclone. Traditionally, Bay of Bengal has been 2 degrees Celsius warmer than Arabian Sea. While the average SST of Arabian Sea is 28 degrees Celsius, that of Bay of Bengal, has been 30degrees Celsius.
“Although cyclones are very intense in terms of air-sea interaction, they are temporally short lived. However, the oceanic mixing process triggered by them could impact the SST for a longer time. The cooling in the case of Cyclone Nargis lasted at least a fortnight.
Thus, the Bay of Bengal can cool twice a year during spring-summer and fall-winter periods through episodic occurrence of cyclonic systems. This cyclone-induced cooling of the upper waters of the Bay of Bengal will increase with enhanced occurrence of the numbers of cyclonic systems, which in turn leads to a slowdown in the rise of the basin-wide SST.
However, it is not clear how long the present trend of slowdown in SST warming continue in the Bay of Bengal,’’ NIO’s Chief Scientist, S Prasanna Kumar, who was part of the study, said.
He added that in the long run, if the same trend continues, due to the lesser warming rate, for each decade, the temperature may decrease by at least less than a degree.
