A New Sea Surface Roughness Parameterization and Its Application in Tropical Cyclone Modeling

The intensity simulation of tropical cyclones (TCs) has been a long-standing challenge for numerical models, and an accurate sea surface roughness () parameterization scheme is the key to enhance the intensity prediction. In our study, a new parameterization scheme (SD21) is proposed and applied in the Coupled Ocean-Atmosphere-Wave-Sediment Transport model to simulate two super typhoons. The SD21 takes into account both the wave state and sea foam, and it is suitable for low to extreme wind conditions. The results of the eight numerical experiments show that the TC intensity and structure are sensitive to the choice of parameterization schemes. Compared with the widely used parameterization schemes, the SD21 scheme presents much better results in the simulation of the intensity and intensification speed of strong TCs. Notably, the simulation of the wind speeds generated by the SD21 is more compatible with the best track data and significantly better than that of the other schemes. Furthermore, we find that the wave state and sea foam remarkably affect the magnitude and spatial distribution of , the following two conclusions are obtained: (a) The parameterization that takes into account the wave state can reduce the excessive roughness at the TC periphery and restrict the high-value area of the roughness to the TC-core region. (b) The sea foam significantly decreases the roughness value in areas with 10 m wind speeds above 40 m/s.