A growing number of cyclones are experiencing multiple rapid intensification globally where a tropical cyclone intensifies dramatically in a short period like an increase in the cyclone’s intensity of 30 knots speed or more in 24 hours and this poses significant challenges to cyclone forecasting, said scientists of the Indian National Centre for Ocean Information Services (INCOIS).
In the latest study conducted in collaboration with researchers from Department of Meteorology and Oceanography, College of Science and Technology, Andhra University, Visakhapatnam, the scientists have deduced that global warming has heightened cyclone intensity, multiple rapid intensifications leading to unpredictability of cyclone behaviour.
“We have observed that tropical cyclones are intensifying rapidly and frequently. We also found changes in their lifecycles. Previously, this rapid intensification used to occur during initial stages of cyclones’ life, but now, with ocean warming, it is occurring even in the mature stages,” explained first author and INCOIS scientist N. D. Manikanta.
The team saw a significant surge in the frequency of multiple rapid intensifications across all ocean basins with western north Pacific Ocean basin contributing to nearly half of the total occurrences and the north Indian Ocean basin having a comparatively low rate.
“Increased number of multiple rapid intensification tropical cyclones in the past 20 years warrant improvement of existing numerical models. We hope to improve our understanding using new observational strategies such as drones and developing AI-based techniques for reducing uncertainties,” said INCOIS head of the Applied Research and Research to Operations (ARO) Sudheer Joseph, also the corresponding author.
Scientists said examining the variations in the intensification rates across time and at different stages of cyclone evolution will help understand correctly when such events occur. Warming of the surface ocean from anthropogenic climate change is fuelling more powerful tropical cyclones, more studies are needed to draw a relationship between the recent climate changes and factors behind rapid intensification of these cyclones, they said.
The team had used publicly available tropical cyclone data — recent and historical — from multiple agencies to create a unified, publicly available dataset including from the National Hurricane Center (for the North Atlantic and eastern-north Pacific basins) and data from the Joint Typhoon Warning Center (for the remaining ocean basins) and analysed 40-year (1981 to 2020) tropical cyclone intensity changes across all global ocean basins.
“These findings will contribute to our knowledge base for understanding the impacts of future climate change on the behaviour of cyclones. It is an important element in developing Ocean Climate Change Advisories under the Deep Ocean Mission,” said INCOIS director Dr. T. Srinivasa Kumar. The study published recently in Scientific Reports highlights the vital importance of better forecasting and preparedness to preserve coastal communities and infrastructure.
