Mode frequency shifts Δν vs. spot amplitude ϵ for modes with ℓ = 2, n = 12 and | m | = 0,1,2 in the case of a polar spot model with r_c = 0.98. The QS eigenfrequency for these modes is ν₀ = 1970.50 ± 0.16 μHz. Dashed lines represent linear frequency shifts given by Eq. (9), red asterisks are frequency shifts from numerical simulations. Solid red lines represent parabolic fits to the shifts. The horizontal dotted line shows the crossing of the frequencies between the m = 0 and | m | = 1 modes at ϵ ≃ 0.92.