Growing Threat of Rapidly-intensifying Tropical Cyclones in East Asia

This study examines the long-term change in the threat of landfalling tropical cyclones (TCs) in East Asia over the period 1975-2020 with a focus on the rapidly-intensifying (RI) TCs. The increase in the annual number of RI-TCs over the western North Pacific and the northwestward shift of their genesis location lead to an increasing trend in the annual number of landfalling RI-TCs along the coast of East Asia. The annual power dissipation index (PDI), a measure of the destruction potential of RI-TCs at landfall, also shows a significant increasing trend due to increases in the annual frequency and mean landfall intensity of landfalling RI-TCs. The increase in mean landfall intensity is related to the higher lifetime maximum intensity (LMI) and the LMI location of the landfalling RI-TCs being closer to the coast. The increase in annual PDI of East Asia is mainly contributed by those in the southern (the Philippines, south China and Vietnam) and northern parts (Japan and the Korean Peninsula) of East Asia through long-term changes in vertical wind shear and TC heat potential. The former leads to a northwestward shift in the favorable environment for TC genesis and intensification, resulting in the northwestward shift in the genesis, RI and LMI locations of RI-TCs. The latter provides more heat energy from the ocean for TC intensification, increasing its chance to undergo RI.