26 June 2014

Increase in the Intensity of Post-monsoon Bay of Bengal Tropical Cyclones


The post-monsoon season (October-November) in the Bay of Bengal has spawned some of the deadliest storms in recorded history. The Bay of Bengal is a marginal tropical cyclone basin that produces only three to four cyclones annually, on average.  However, its semi-enclosed nature coupled with a shallow bathymetry and the high population density of surrounding nations cause tropical cyclones in this basin to have devastating consequences when they make landfall. A team of scientists led by Department of Energy researchers at Pacific Northwest National Laboratory, used cyclone track data to identify changes in post-monsoon Bay of Bengal tropical cyclone activity during the 30-year post-satellite period 1981-2010. The researchers found that an increase in the intensity of tropical cyclones over the study period and a robust increase in the rate at which cyclones intensify. While an increase in sea surface temperatures and upper-ocean heat content make the ocean more favorable for cyclone development, enhanced instability in the lower-level atmosphere promotes the growth of tropical cyclones. Over the period, all the oceanic and atmospheric changes displayed positive linear trends, suggesting that future post-monsoon Bay of Bengal cyclones may continue to increase in intensity. These results have important implications for understanding and modeling how tropical cyclones respond to climate change in the future.

Kathik Balaguru
Pacific Northwest National Laboratory (PNNL)
Balaguru, K, S Taraphdar, R Leung, and GR Foltz.  2014.  "Increase in the Intensity of Postmonsoon Bay of Bengal Tropical Cyclones."  Geophysical Research Letters 3594-3601.  https://doi.org/10.1002/2014GL060197.