Temporal variation of the mode amplitude (left) and frequency (right) taken from Fig. 7, together with surface rotation rates at 60° latitude obtained from MWO Doppler velocity (1983–2013) in solid light blue, and from global helioseismology using MDI (1996–2010) and HMI (2010–2023) data in dashed blue. The beginnings of cycles 21–25 (solar minima) are marked with vertical lines and the cycle numbers are denoted at the top.