Period of Rossby-dynamo waves vs magnetic field strength for the dynamo coefficient, α_z/Ω, of 0.0015 and k_xR = 1 computed from Eq. (16) at the latitude 30⁰ of the solar tachocline. The blue and red lines correspond to the reduced gravity of gH/Ω²R² = 0.085 and gH/Ω²R² = 0.095, respectively. Lower panel: Modified dynamo waves in the magnetic field interval of 0–20 kG, on a solar cycle timescale of 15–45 years. The two solutions of modified dynamo waves correspond to a solar cycle timescale of 15–45 years (lower solution) and to Gleisberg cycle timescales of 45–160 years. Upper panel: Modified fast magneto-Rossby waves in the same interval of magnetic field strength on Rieger cycle timescales of 165–185 days.