Total solar irradiance LC (top-left panel), the prewhitened TSI LC (middle-left panel), the amplitude variation A(t) obtained from the prewhitened TSI LC (bottom-left panel), and Lomb-Scargle periodograms corresponding to each LC (right panels). In the left panels, the dashed vertical lines mark the beginning of each solar cycle, based on review from Hathaway (2010). In the bottom left panel, the A(t) time series is depicted for N_box = 2 (black solid curve) and N_box = 5 (red solid curve), whereas in the bottom right panel the Lomb-Scargle periodogram of A(t) is shown for each N_box value with their respective colors.