a: spectra for transverse waves used in this study. The black curve represents the averaged observed spectrum, the red curve represents a spectrum where the power enhancement at ν₀ = 4 mHz is removed, and the blue curve represents a spectrum where we used a shallower power-law index. b: velocity v_x time series for the three spectra in normalised units with the same coloured legend. c: displacement associated with the velocity time series in normalised units and with the same colour legend. The black dashed curve represents the displacement derived from an additional velocity profile obtained from the same observed power spectrum.