Tropical cyclones (TCs) can cause severe damage to lives, property, and infrastructure, and result in significant economic losses. These circular storms with heavy rainfall and strong winds originate in warm tropical oceans. However, there is no consensus among scientists regarding the impact of climate change on TC frequency and intensity. To gain a holistic understanding of TC characteristics across ocean basins, a recent study published in Atmospheric and Oceanic Science Letters evaluated global TC activity trends from 1980 to 2021.
The study by Professor Wen Zhou of Fudan University, China, and Erandani Lakshani, a post-graduate researcher at the City University of Hong Kong, revealed significant decadal-scale shifts and trends in global TC activities. Over the past four decades, there has been an increase in TCs in the North Atlantic basin and North Indian Ocean, while a decrease has been observed in the western North Pacific. The genesis of TCs in the East Pacific, southern Indian Ocean, and South Pacific Ocean basins has declined since 1980, although this trend is not statistically significant.
TC intensity has also varied significantly among different ocean basins. The study found that the average maximum TC intensity has increased in the North Indian Ocean due to an upward trend in mid-tropospheric relative humidity and decreasing vertical wind shear. Conversely, the average TC intensity has decreased dramatically in the East Pacific but has increased significantly in the South Pacific. The study also indicates an increasing TC intensity trend in the western North Pacific but a decreasing trend in the North Atlantic. The TC intensity in the North Atlantic may be linked to the decreasing trend in mid-tropospheric relative humidity, primarily south of the North Atlantic.
Furthermore, the study revealed a significant association between the average large-scale characteristics of vertical wind shear and relative humidity and TC frequency in different ocean basins. The interdependence of TC frequency, vertical wind shear, and relative humidity varies across the basins, indicating an inter-basin teleconnection.
In summary, this study provides valuable insights into global TC trends, which can improve our understanding of TC evolution. Continued research is necessary to comprehend the underlying causes of these shifts in TC activity for future predictability and preparedness.
Source: Chinese Academy of Sciences