Impact of meridional flow variations on solar cycle asymmetry. Panel (a): temporal evolution of B_ϕ² and meridional flow speed when the flow decreases at the cycle maximum. The black curve (left y-axis) shows the variation of B_ϕ² (a proxy for sunspot number), while the blue curve (right y-axis) shows the meridional flow speed decreasing from a higher to a lower value at the cycle peak. Panel (b): Same as Panel (a), but with the meridional flow increasing from a lower to a higher value at the cycle maximum. Panel (c): variation of the rise-to-decay time ratio as a function of flow asymmetry between the declining and rising phases, expressed as v_declining − v_rising. The red dot corresponds to the mean value of rise-to-decay time ratio.