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

Abstract

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.

On the Rapid Weakening of Typhoon Trami (2018): Strong Sea Surface Temperature Cooling Associated with Slow Translation Speed

“…In contrast, UOC also undergoes an ERC but there is no significant weakening during the ERC and the moat between eyewalls is smaller than in C3D and C1D, which is similar to the intensification of Hurricane Irma during the ERC period (Fischer et al 2020) over a warmer ocean. Note that the limited contraction of the eyewall in the ERC due to SST cooling in our simulations is generally consistent with Yang et al (2019) and Li et al (2022). However, there are still differences between these studies.…”

“…However, there are still differences between these studies. Yang et al (2019) found that the moat is larger in ocean-coupled experiments, but Li et al (2022) found that Trami's moat is not obvious in the coupled simulation. In this study, the moat of Trami is larger in C3D and the duration of the ERC period between coupled and uncoupled runs vary insignificantly, which is different from the simulation in Li et al (2022).…”

“…Ma et al (2020) also discovered the formation of the SBL, but they indicated that the increase of inflow angle is limited in the cold wake area, which is different from Lee and Chen (2014). Yang et al (2019) and Li et al (2022) focused on the effect of air-sea interaction on eyewall replacement cycles (ERCs) in different cases (Sinlaku and Trami). Yang et al (2019) found that the duration of Sinlaku's ERC in fully oceancoupled run is longer and the eyewall structure is asymmetric, which is strongly affected by nonuniform SST distribution.…”

“…Yang et al (2019) and Li et al (2022) focused on the effect of air-sea interaction on eyewall replacement cycles (ERCs) in different cases (Sinlaku and Trami). Yang et al (2019) found that the duration of Sinlaku's ERC in fully oceancoupled run is longer and the eyewall structure is asymmetric, which is strongly affected by nonuniform SST distribution. Without considering ocean feedback, the duration of ERC is shorter than observation and the eyewall is more axisymmetric.…”

“…Without considering ocean feedback, the duration of ERC is shorter than observation and the eyewall is more axisymmetric. Li et al (2022) followed up on the work of Yang et al (2019) and simulated Trami with both coupled and uncoupled models. They found that Trami's inner-eyewall decayed more rapidly due to the strong sea surface cooling in the inner core, which resulted in a shorter ERC period.…”