Bandpass-filtered images of the LOS Doppler velocity, V_los, and LOS magnetic field, B_los, derived from HMI data. Top left: Filtered V_los image from 14 June 2020. Bottom left: Central-meridian V_los values stacked over time and plotted as a function of time and latitude. Right panels: Corresponding B_los data, with low-latitude regions (< 45°) shaded out. The filtering was performed using a bandpass filter centered at ${\nu }_{\mathrm{HL}1}^{\mathrm{synodic}}=338$ nHz with a full width of 30 nHz, applied over the entire available HMI time period, i.e., from 2010 to 2024. For clarity, the images were smoothed with a Gaussian kernel with a width of 2 pixel – in longitude and latitude (top panels) and in time and latitude (bottom panels). A movie is available as online supplementary material.