Continuation of Fig. 3. From top left to bottom right: zoomed-in region (frame in Fig. 3, left) showing attractive LCS calculated for successive negative tracer integration times (red colormap), superimposed with passive tracer locations (black dots) and corresponding local B_z magnetograms (same green/purple colormap as in Fig. 3) at corresponding positive integration times. As mentioned in Sect. 3, tracers accumulate in attractive LCS. Throughout the sequence, LCS and tracer concentrations correlate well with the magnetic network and bright points, respectively. The coloured markers and lines tag (positive-time) trajectories of a few selected tracers: large symbols mark the initial position and current position for the time of integration of each plot, and small symbols the position for every intermediate 24 h (see discussion in Sect. 5 and Fig. 7).