Slit-reconstructed FWHM (rows 1 and 3) and line-core (rows 2 and 4) velocity maps. The maps are scaled between ±10 km s⁻¹. Black and white corresponds to upflows and downflows, respectively. The colored plus signs (+) and crosses (×) are persistent blue- and redshifted regions recognized by using the average of 20 velocity maps with LOS velocities of ±3 km s⁻¹. The corresponding Hα profiles are shown in Fig. 6. The intensity and contrast profiles along the green lines in panels 7 – 9 are displayed in Fig. 8. The accompanying online movie provides a visualization of the temporal changes of these two parameters.