Panels a) to c): same as in Fig. 2. Panel a) shows the Hinode SP map now rebinned to the IRIS slitjaw scale with the same contours as in the second row of Fig. 1 and the horizontal flows indicated with colored arrows as in Fig. 1. The two vertical white lines delimit the position of the IRIS slit in use. Two dashed red horizontal lines and a solid red line mark a region of interest. Panels b) and c) are time-space images derived from spectra recorded by the second IRIS slit. Panel b) shows the line-core velocity of the Fe i 2799.9 Å  line (±1.9 km s^-1, where down flows are positive) retrieved with the MOSiC code and in panel c) the intensity of the Mg ii k2v peak (in data units) obtained by the iris_get_mg_features_lev2.pro code is plotted. The red horizontal lines indicate the same area as in panel a). The short vertical line in cyan indicates the time of the maps displayed in panel a). In panel d) the spectral profile recorded by IRIS is plotted with a solid line as well as an average quiet Sun spectrum (dotted). The dashed vertical lines denote the average position of the Mg ii k2 peaks. The arrows point to the Mg ii k2v peak, the wing of the Mg ii 2798.8 Å  line, and the position of the Fe i 2799.9 Å  line used in panel b). See online movie.