Effects of Air-Sea Interaction on the Eyewall Replacement Cycle of Typhoon Sinlaku (2008): Verification of Numerical Simulation

To explore the effects of air-sea interaction on the eyewall replacement cycle (ERC) of tropical cyclones (TCs), an ERC of Typhoon Sinlaku (2008) was reproduced using the high-resolution coupled ocean-atmosphere-wave-sediment transport (COAWST) model. The numerical simulations were evaluated with a wide range of observational datasets. Moreover, the importance of the ocean to ERC is discussed by comparing six sensitive experiments, that is, three uncoupled experiments with different time-invariant sea surface temperatures, an ocean-atmosphere coupled experiment, an ocean-wave coupled experiment, and an ocean-atmosphere-wave fully coupled experiment. The results show that Sinlaku simulated by the fully coupled experiment was highly consistent with the observations, and the evolution of ERC varies from those only simulated by the atmospheric models in previous studies. When the ocean and waves were both considered, the lifetime of the ERC was significantly prolonged, even though the simulated Sinlaku was weakened by the cooling of the sea; the asymmetric distribution of the concentric eyewalls (CEs) which caused by the non-uniform energy exchanges was also prominent. By contrast, without ocean coupling, the simulated secondary eyewall, composed of axisymmetric convections, exhibited false enhancement and fake inward contraction, and the duration of the ERC was also shorter than that actually observed. In conclusion, the results highlight the significance of ocean coupling for the numerical simulation of the ERC of a TC, including survival time and asymmetric structure.