AUTHOR=Kim Sung-Hun , Kang Hyoun-Woo , Moon Il-Ju , Kang Sok Kuh , Chu Pao-Shin 

TITLE=Effects of the reduced air-sea drag coefficient in high winds on the rapid intensification of tropical cyclones and bimodality of the lifetime maximum intensity

JOURNAL=Frontiers in Marine Science

VOLUME=Volume 9 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.1032888

DOI=10.3389/fmars.2022.1032888

ISSN=2296-7745

ABSTRACT=The air-sea drag coefficient (Cd) is closely related to tropical cyclone (TC) intensification. Several recent studies have suggested that the Cd decreases in winds greater than 33 m s−1. The effects of Cd reduction in high winds on TC intensity, especially rapid intensification (RI) and the lifetime maximum intensity (LMI) distribution, were investigated by analyzing the wind-dependent Cd-based ocean vertical mixing and the energy budget. The results show that the reduced Cd in high winds drives an increase in net energy by reducing the frictional dissipation and suppressing sea surface cooling. This extra energy prevents the TC from achieving a steady-state, causing the bimodality of simulated maximum potential intensity. The observed steady-state probability (intensification rate and RI probability) in the Cd reduced wind range were significantly lower (higher) than in the others. These results suggest that Cd reduction might potentially induce the RI and the LMI bimodality.