Bay of Bengal Cyclones: El Niño Years See Fewer Storms, Study Finds
A new study from Indian scientists reveals that the El Niño climate pattern significantly influences the number of tropical cyclones forming in the Bay of Bengal during the post-monsoon season (October to December). The research, conducted by the Indian National Centre for Ocean Information Services (INCOIS) in Hyderabad, analysed cyclone activity from 1995 to 2019.
El Niño, the warming of sea surface temperatures in the central and eastern Pacific Ocean, is already known to affect India's monsoon. Its counterpart, La Niña, involves cooler sea surface temperatures in the same region. The study found that cyclone formation varies greatly depending on which phase of the El Niño Southern Oscillation (ENSO) is active.
During the nine El Niño years studied, only 15 cyclones formed. In contrast, La Niña years saw more than double that number—33 cyclones over 11 years. Neutral years also showed relatively high activity, with 17 cyclones in five years.
The researchers, P. Suneeta, T.V.S. Udaya Bhaskar, and S.S.V.S. Ramakrishna, used the Genesis Potential Index (GPI) to measure how favourable conditions are for cyclone development. GPI values during La Niña were nearly twice as high as during El Niño or neutral years, due to lower vertical wind shear, warmer sea surface temperatures, and stronger air-sea interactions.
Tropical cyclones are among the most destructive weather systems in the Bay of Bengal region, causing widespread damage through strong winds, heavy rainfall, and storm surges. Understanding the role of ENSO could improve cyclone forecasting and help in disaster preparedness, the scientists noted.
However, the study's authors caution that more research with longer data records is needed to fully understand the mechanisms. The work was carried out under the Ministry of Earth Sciences in collaboration with Andhra University, Visakhapatnam.
