Better understanding the patterns of tropical cyclones for improved prediction and damage control.

Tropical cyclones (TCs) are one of the most destructive types of weather events on Earth, damaging people’s lives and property, and local infrastructure, and thus causing huge economic losses. TCs are powerful circular storms that originate in warm tropical oceans and are accompanied by heavy rainfall and strong winds.

However, there was no consensus among scientists regarding global trends in TC frequency and severity due to the effects of climate change on ocean temperatures. Hence, to achieve this, and to better prepare for these extreme weather events in the future, comprehensive assessment of different TC properties across ocean basins is vital.

In a recent study published in Atmospheric and Ocean Science LettersProfessor Wen Zhou of Fudan University, China, and Irandani Lakshani, a postgraduate researcher at the City University of Hong Kong, shed further light on the remarkable decade-wide shifts and trends in global technical cooperation activities from 1980 to 2021.

The study reveals a significant increase in TCs in the North Atlantic and North Indian Ocean basin over the past four decades, while there has been a decrease in the western North Pacific. It was also found that the genesis of TCs in the Eastern Pacific, South Indian and South Pacific basins has declined since 1980, although this trend is not statistically significant.

Besides the frequency of TC genesis, the intensity of TCs also varied significantly between different ocean basins.

“Remarkably, the average TC maximum intensity over the northern Indian Ocean has increased significantly recently, and this can be explained by an upward trend in mid-tropospheric relative humidity and a decreasing vertical wind shear in this basin,” says Professor Chu and Lakshani. Their study also indicates that the average TC density in the eastern Pacific has decreased significantly, while it has increased significantly in the southern Pacific.

Furthermore, they observed an increasing trend in TC intensity in the western North Pacific but a decreasing trend over the North Atlantic. The intensity of TC in the North Atlantic may be related to the downward trend of relative humidity in the mid-troposphere, especially in the southern North Atlantic.

Another result of this work is the indication of a significant correlation between the average large-scale characteristics of both vertical wind shear, relative humidity, and TC frequency in different ocean basins. Moreover, the correlation between TC frequency, vertical wind shear and relative humidity varies across basins, suggesting a remote connection between basins (a term used in atmospheric science to describe climatic linkages between geographically separated regions).

In summary, this study provides valuable insights into global TC trends, which is critical to improving our understanding of the evolution of TCs. Furthermore, the study highlights the need for further research into the reasons behind these shifts in TC activity for future predictability and preparedness.