Model dispersion relations for all the modes with −Im[ω]/2π < 100 nHz. Shown are the Rossby modes (black curves for R, R₁, and R₂), the high-latitude modes (red area), the strongly damped modes (blue area), and the critical-latitude modes (orange area). The differential rotation is solar (N = 30), both at the surface (r = R_⊙ and E = 4 × 10⁻⁴, left panel) and at the bottom of the convection zone (r = 0.75 R_⊙ and E = 2 × 10⁻⁵, right panel). Frequencies are expressed in the Carrington frame of reference. The symbols show the observed modes reported by Gizon et al. (2021).