The Xiamen Symposium on Marine Environmental Sciences (XMAS 2025)

The destructive potential of tropical cyclones (TCs) is primarily determined by two key factors: intensity and the size of the outer region. While the impact of TC wind structure on TC intensification rates has been extensively studied, little has been done to explore its effect on the growth of the outer region. This study investigates the relationship between the growth of the 34-kt wind radius (R34) of TCs and their fullness using best-track data from 2001 to 2020. The storms were categorized into four groups based on a fullness scale: FS1 (fullness ≤ 0.4), FS2 (0.4 < fullness ≤ 0.6), FS3 (0.6 < fullness ≤ 0.8), and FS4 (fullness > 0.8). These groups exhibit unique spatial patterns of very deep convective clouds with infrared brightness temperatures <208 K. The mean R34 growth rates in 24 hr decrease from FS1 to FS4, which is linked to the higher coverage of very deep convection around R34 in storms with lower fullness. This study demonstrates that TC fullness can characterize the spatial distribution of deep convection in storms and serve as a representation of the growth of TC outer region size. These results have implications for understanding the mechanisms behind TC outer size growth.

tropical cyclone