Hyderabad: Climate change leading to alterations in the wind systems of the Pacific Ocean could be causing tropical cyclones in the Bay of Bengal.
Scientists believe that changes in the wind systems of the Pacific Ocean, due to the ‘La Nina’ effect are actually causing cyclonic systems to move towards the Bay of Bengal.
Most of the cyclones that have hit the coast over the last couple of months have had their genesis in the Pacific Ocean.
Experts also say that there is evidence that the Pacific Ocean is getting warmer in recent years, and this is also a factor in increased activity.
Cyclones Phailin, Nari and Haiyan originated in the Pacific Ocean and weakened after hitting the Philippines and Vietnam. However, the weakened systems continued to move into the Andaman
Sea and Bay of Bengal and then were reinvigorated by the moisture and temperature they encountered there.
Notably, it is also quite easy for weakened cyclonic systems to move into the Andaman Sea owing to the extremely Malay Peninsula that needs to be crossed. Scientists say that the primary reason
behind Pacific cyclonic systems moving towards the Bay of Bengal is La Nina, the other extreme of El Ni-no Southern Oscillations.
Scientists: Pacific is warming up
Moisture, vorticity and sea surface temperature are the major factors aiding cyclones in the Bay of Bengal.
Research conducted by scientists suggests that changed wind patterns due to La Nina favour moisture accumulation over the Bay of Bengal which supports enhanced convection.
Prof VSN Murthy, Chief Scientist, CSIR, National Institute of Oceanography (NIO), explained, “This time we have seen three big Pacific cyclones enter the Bay of Bengal and re-energise. Changes in the wind systems of the Pacific Ocean are creating favourable conditions for cyclones to shift towards Bay of Bengal.”
Scientists also say that Pacific Ocean warming up is another factor.
Prof SSVS Ramakrishna, Head of Department, Meteorology and Oceanography, Andhra University, said, “It has been noted that the Pacific Ocean is getting warmer in recent years, which is giving rise to a lot of cyclonic activity which is then pushed towards the Bay of Bengal. This is due to a change in currents there and plate tectonic activity.”
The intensity of cyclones in the Bay of Bengal is increasing due to this. Last year, Cyclone Nilam had its origins in the Pacific Ocean.
NASA also noted the reawakening of the Haiyan storm.
“The former tropical storm known as 30W that moved from the western North Pacific Ocean basin into the northern Indian Ocean appears to be ramping up for a short stint at depression status again.” The depression to be named Helen, however, fizzled out and wasn’t categorised as a cyclone by the Indian Meteorological Department (IMD) although the US Navy Typhoon Warning Centre did.
