Eigenfunctions for the symmetric modes R, P₄, S₂, and A₆ (top row, ψ_s) and for the antisymmetric modes P₃, S₃, and A₅ (bottom row, ψ_a). See Fig. 4 for the position of the corresponding eigenvalues in the complex plane. The real and imaginary parts are plotted with solid and dashed lines, respectively. The modulus of the eigenfunctions is normalized to one. By choice, all imaginary parts are zero at the equator.