14:15 〜 14:30
[AAS10-15] Impacts of Interactions Between Typhoons, Ocean Wave Development, and Upper Ocean Cooling on Cyclone Characteristics
★Invited Papers
キーワード：台風‐波浪‐海洋相互作用、大気海洋波浪結合モデル、海面粗度、運動量交換係数
Global warming is projected to intensify typhoons in the Northwest Pacific, making accurate forecasts essential for mitigating the increasing risks of strong winds, storm surges, and coastal damage. While upper ocean responses and wave development significantly affect typhoon intensity and size, their roles remain underexplored, introducing uncertainties into current forecasting models. Understanding these mechanisms is crucial for improving the accuracy of typhoon forecasts and reducing disaster risks in regions with significant typhoon damage.
This study investigates the impacts of upper ocean cooling and wave development on typhoon characteristics using the coupled numerical model COAWST (Warner et al., 2010), which integrates WRF (Weather Research and Forecasting model), ROMS (Regional Ocean Modeling System), and WW3 (WaveWatch III). We targeted Cimaron and Jebi (2018) and Faxai and Hagibis (2019). These typhoons with varying characteristics were analyzed through simulations conducted with an atmospheric model, an atmosphere-ocean coupled model, an atmosphere-wave coupled model, and a fully coupled atmosphere-ocean-wave coupled model. The wave effects were analyzed using three surface roughness parameterizations (Taylor and Yelland, 2001; Drennan et al., 2003; Oost et al., 2002), considering wave height, wave steepness, wavelength, and age.
The results revealed that ocean cooling and wave development produce distinct feedback mechanisms depending on typhoon characteristics. Typhoon tracks were minimally affected by ocean and wave interactions. Ocean cooling significantly weakened typhoon intensity. The central pressure of Hagibis increased by up to 34.42 hPa, while Cimaron showed an increase of 11.43 hPa. Maximum wind speeds generally decreased due to ocean cooling, but wave coupling improved alignment with best-track data. Ocean effects were stronger for intense typhoons, while wave effects were more significant for axisymmetric typhoons. Additionally, coupling ocean and wave effects led to consistent patterns of an increased radius of maximum wind speed and a reduced radius of 15 m/s winds across all cases.
Analysis of the relationship between sea momentum exchange coefficient based on surface roughness and wind speed showed that the Taylor and Yelland parameterization deviates from linearity and approaches a constant value for wind speeds above 30 m/s, consistent with observed and experimental momentum exchange coefficient trends. Further tuning is required for other parameterizations.
These findings highlight the necessity of incorporating coupled models to enhance the accuracy of typhoon forecasts and improve disaster preparedness and mitigation strategies in regions severely affected by typhoons.
This study investigates the impacts of upper ocean cooling and wave development on typhoon characteristics using the coupled numerical model COAWST (Warner et al., 2010), which integrates WRF (Weather Research and Forecasting model), ROMS (Regional Ocean Modeling System), and WW3 (WaveWatch III). We targeted Cimaron and Jebi (2018) and Faxai and Hagibis (2019). These typhoons with varying characteristics were analyzed through simulations conducted with an atmospheric model, an atmosphere-ocean coupled model, an atmosphere-wave coupled model, and a fully coupled atmosphere-ocean-wave coupled model. The wave effects were analyzed using three surface roughness parameterizations (Taylor and Yelland, 2001; Drennan et al., 2003; Oost et al., 2002), considering wave height, wave steepness, wavelength, and age.
The results revealed that ocean cooling and wave development produce distinct feedback mechanisms depending on typhoon characteristics. Typhoon tracks were minimally affected by ocean and wave interactions. Ocean cooling significantly weakened typhoon intensity. The central pressure of Hagibis increased by up to 34.42 hPa, while Cimaron showed an increase of 11.43 hPa. Maximum wind speeds generally decreased due to ocean cooling, but wave coupling improved alignment with best-track data. Ocean effects were stronger for intense typhoons, while wave effects were more significant for axisymmetric typhoons. Additionally, coupling ocean and wave effects led to consistent patterns of an increased radius of maximum wind speed and a reduced radius of 15 m/s winds across all cases.
Analysis of the relationship between sea momentum exchange coefficient based on surface roughness and wind speed showed that the Taylor and Yelland parameterization deviates from linearity and approaches a constant value for wind speeds above 30 m/s, consistent with observed and experimental momentum exchange coefficient trends. Further tuning is required for other parameterizations.
These findings highlight the necessity of incorporating coupled models to enhance the accuracy of typhoon forecasts and improve disaster preparedness and mitigation strategies in regions severely affected by typhoons.