Numerical study of the effects of ocean waves and sprays on Typhoon “Shan Shan”

Typhoon is a severe weather system. Over the open sea, strong winds are able to stir up big waves and change the sea surface roughness. When the white foam breaks on the top of waves, a lot of sprays are produced in the airsea interface. Based on the shared memory and semaphores interprocess communications in the Linux system, the coupled mesoscale atmospherewave model is used in the simulation of typhoon “Shan Shan” with the involvement of the Fairall or Andreas sea spray parameterization. The results show that the airsea interaction has influence on the typhoon intensity, but little effect on the typhoon track. Since the coupled model considers the impact of ocean status on the sea surface roughness, the simulated typhoon intensity is closer to the observation than the uncoupled model. The air-sea interaction influences typhoon in terms of dynamic fields and, the momentum flux is changed with the sea surface roughness. Whether the simulated typhoon is realistic or not is largely determined by the matching condition between the simulated ocean status and the observation. The sea spray affects the dynamic structure through thermodynamic fields. The latent and sensible heat fluxes in the Fairall parameterization are significantly increased, which changes the thermodynamic structure of the typhoon and strengthens it. The interface flux calculated via the Andreas parameterization under highrelative humidity conditions is small, and, as a result, although the sensible heat flux is increased under high wind speed conditions, the total latent and sensible heat fluxes via the Andreas parameterization are smaller than those via the Fairall parameterization, resulting in a weaker typhoon. The sea spray has effect on the typhoon track through changes in its structure and intensity.