Tropical Cyclone Exposure in the North Indian Ocean

The North Indian Ocean is a region with a high coastal population and a low-lying delta, making it a high-risk region for tropical cyclone impacts. A 30-year period from 1989-2018 has been used to examine the TC landfalling exposure in the North Indian Ocean and its changes by considering 30 years of IBTrACs data, ERA5 atmospheric data, and 20 years of TRMM and DAV data. A total of 185 TCs made landfall in the NIO during the 30-year period with the majority of the TCs making landfall during the pre- and post-monsoon seasons. Rainfall associated with landfalling TCs decreased in the last 10 years of analysis (2009-2018) compared to the first 10 years of available data from 1999-2008. During the monsoon, TC activity is relatively lower compared to the post-monsoon periods, even though higher accumulated TC-associated rainfall typically occurs during the monsoon period, particularly along the eastern coastlines of the Arabian Sea and the Bay of Bengal. The TC winds impact most of the Bay of Bengal coastline, including Sri Lanka. The spatial distribution of landfalling TCs changes with the season, with most of the landfalling activity occurring during the pre- and post-monsoon periods. Interestingly, more recent TC activity has shifted to the northeast India and Bangladesh coasts, suggesting that these regions may be more vulnerable to TC impacts in the future.

Automated summary

The North Indian Ocean is a high-risk region for tropical cyclone impacts due to its high coastal population and low-lying delta. The study analyzed data from a 30-year period to examine the frequency of tropical cyclone landfall and changes in the region. The findings showed that most tropical cyclones made landfall during the pre- and post-monsoon seasons, with a decrease in rainfall associated with landfalling cyclones in recent years. Interestingly, the activity of tropical cyclones has shifted towards the northeast India and Bangladesh coasts, indicating potential vulnerability in these regions.