Longitudinal (left) and transverse (right) velocities multiplied by and , respectively, for the simulation run with a vertical periodic driver. The black solid line is the location of the cut-off frequency for the 200 s period waves, the dashed black lines are the β = 1 contours, and the red line shows the transition region. The magnetic field lines are inclined black lines. Positive velocity (red color) is an upflow. The movie of the wave propagation is available online.