Period of Rossby-dynamo waves vs magnetic field strength for the dynamo coefficient, α_z/Ω, of 0.12 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 = 0.003 and gH/Ω²R² = 0.005, respectively. Upper panel: Modified dynamo waves in the magnetic field interval of 20–70 kG, which have the Rieger cycle timescales of 130–200 days. Lower panel: Modified fast magneto-Rossby waves in the same interval of magnetic field strength, which have solar cycle timescales of 10–40 years.