Spatial profiles of the oscillating magnetic field lines (of maximum amplitude; black curves) for the fundamental, 1st-order, and 2nd-order harmonics (from left to right), corresponding to Fig. 3, Fig. 4a and b, respectively. The gray curve is the same background field line at rest and the cross symbol denotes the footpoint. The view angle of each panel is altered separately in order to optimize the visualization of each oscillation pattern and amplitude.