Analysis of the effects of differential rotation on sectoral Rossby modes with no nodes in radius (n_RZ = n_CZ = 0, ℓ_RZ = m). (a) Meridional cross-sections of u_θ and u_ϕ of the Rossby modes computed under uniform rotation for different azimuthal orders, m. The longitudes corresponding to the real and imaginary components are designated in the same way as in Fig. 3. The frequencies and the growth rates measured in the Carrington frame are noted below the eigenfunctions. All eigenfunctions are normalized to have a maximum u_θ of 1 m s⁻¹ at the surface. The dotted lines indicate the position of the CZ base. (b) Same as (a) but under the simplified differential rotation given by Eq. (5), shown in Fig. 1. (c) Radial profiles of the RMS velocity of the modes computed with and without differential rotation. The colours of the shaded regions have the same meaning as in Fig. 2.