Regional internal tide models need prudent eddy viscosity selections for dependable estimations.

This article focuses on the influence of eddy viscosity and mixing parameterization schemes on numerical simulations of internal tides (ITs) in the Luzon Strait (LS) and the South China Sea (SCS). Using the Massachusetts Institute of Technology general circulation model (MITgcm), the study finds that increasing horizontal eddy viscosity above 100 m²/s and vertical eddy viscosity above 10⁻² m²/s significantly improves simulation accuracy and enhances baroclinic energy dissipation in the LS. The Leith horizontal mixing scheme notably improves model performance, whereas the K-profile parameterization (KPP) vertical mixing scheme tends to increase simulation errors. These results suggest that appropriate selection and parameterization of eddy viscosities are critical for reducing discrepancies in IT energetics and improving regional IT modeling.