Numerical test starting from an initial dipolar magnetic field with a maximum strength of 10 G to illustrate the role of the latitude-dependent latitudinal shear in generating the equatorward migration of the toroidal field. Left panel: regeneration pattern of the average toroidal magnetic field within the range 0.7 R_⊙ to R_⊙, $\overline{B_{\varphi }}$. The dash-dotted and dotted curves represent the time evolution of the latitudes at which $\overline{B_{\varphi }}$ reaches 100 G and 300 G, respectively. Right panel: comparison of the time-latitude dependence of $\overline{B_{\varphi }}=100$ G (green) with observations measured based on sunspot records by Hathaway (2011, H11, orange) and by Jiang et al. (2011a, J11, red).