(a) Dispersion relations of the equatorial Rossby modes for the cases with solar differential rotation. Red and blue curves represent the modes with no radial nodes (n = 0) and one radial node (n = 1), respectively. Solid and dashed lines denote the cases with weak diffusion (ν = 10¹¹ cm² s⁻¹) and strong diffusion (ν = 10¹² cm² s⁻¹), respectively. For comparison, the observed Rossby mode frequencies reported in Löptien et al. (2018), Liang et al. (2019), and Proxauf et al. (2020) are plotted by white hexagons and squares. All the presented frequencies are measured in the Carrington frame rotating at Ω₀/2π = 456.0 nHz. (b) Mode linewidths versus mode frequencies. Each point represents a mode with azimuthal order m, which is labeled with small integers from m = 1 to 16. Overplotted (open circles connected by black lines) are the mode linewidths and frequencies measured by Proxauf et al. (2020) for m = 3 to 15. In both panels, the green dots connected by line segments refer to a theoretical model for the simplified case of uniform rotation, ω/Ω₀ = −2/(m + 1)−iE_km(m + 1), where E_k = 4 × 10⁻⁴ is the Ekman number at the solar surface (Fournier et al. 2022).