Velocity spectra for the horizontal velocity computed through local correlation tracking applied to continuum images near the Fe I 5250.2 Å line from the IMaX observations and from synthetic observations obtained from the simulation runs. Left panel: first (dashed black) and second (solid black) IMaX time series and the HD simulation run (solid green). Right panel: spectra from the four simulation runs (green: HD run; red: MHD 50 G run; dashed orange line: MHD 100 G run; dashed black line: MHD 200 G run). The corresponding portion of the second IMaX time series (solid black line) is added for comparison.