(a) Growth rate versus frequency of the ζ_z-antisymmetric high-latitude mode with m = 1, for different values of the latitudinal entropy difference |Δ_θs|=s_0, pole − s_0, eq. The red star is for the case of a realistic latitudinal entropy gradient that depends on position, estimated according to Eq. (27). Realistic solar differential rotation is included. The background stratification is adiabatic (δ = 0) and the diffusivities are set to ν = κ = 10¹² cm² s⁻¹. (b)–(f) Eigenfunctions of the longitudinal velocity v_ϕ at the surface (r = 0.985 R_⊙) and at the central meridian for some selected Δs_θ. The eigenfunctions are normalized so that the maximum flow amplitudes at the surface is v_ϕ = 10 m s⁻¹.