Effects of Sea Spray and Ocean Currents on Tropical Cyclone Intensification Based on the Coupled Atmosphere-Wave-Ocean Model Experiments

Accurately simulating the complex interactions between the ocean and atmosphere is crucial for improving the forecasting of tropical cyclone (TC) intensity. Despite significant advancements in TC modeling, challenges remain in effectively representing key processes that govern the transfer of heat and momentum between the ocean surface and the atmosphere. This study investigates the impacts of sea spray, surface roughness, and ocean currents on these fluxes and their subsequent influence on the intensification of strong TCs in the western North Pacific. Sea spray is known to significantly affect heat and momentum fluxes in the atmosphere, yet it is often modeled solely as a function of wind speed, neglecting the effects of wave breaking. Similarly, surface roughness is frequently parameterized based on wind speed alone, overlooking the potential influence of wave-dependent roughness length on momentum flux. Additionally, while momentum flux between the ocean and atmosphere is typically determined by the difference between wind speed and current speed, the latter is often disregarded due to its relatively smaller magnitude. However, considering the presence of the TC-induced current, Kuroshio Current, and regional tidal influences around the Korean Peninsula, it is essential to explore the impact of ocean currents on momentum flux. This study employs a coupled atmosphere-wave-ocean model to analyze how these factors—sea spray, surface roughness, and ocean currents—affect heat and momentum fluxes and ultimately influence the intensity of TCs. Through sensitivity experiments, we quantitatively assess the effects of these interactions, aiming to improve the accuracy of TC intensity predictions. The findings contribute to enhancing our understanding of air-sea interactions and their role in TC dynamics, providing valuable insights for better forecasting of severe weather events.

Acknowledgement: This research was supported by the Korea Meteorological Administration Research and Development Program under Grant (RS-2023-00239702) and the Korea Institute of Marine Science & Technology Promotion (KIMST) funded by the Ministry of Oceans and Fisheries (RS-2022-KS221667) and a part of the project titled “Development of technology to predict potential maximum intensity of tropical cyclone for nuclear power plant sites", funded by the Korea Hydro & Nuclear Power Co., Ltd. (KHNP).