Panel a: observed field-of-view (FOV) on 14 November 2010 in the continuum. Panels b and c: depression of the line core of the Si i 10 827 Å  line and He ibc, respectively. The inner and outer contours in all panels indicate the umbra-penumbra boundary and the outer boundary of the sunspot, respectively. The arrow in panel a indicates the direction to the solar disk center. Three white arrows in panel c mark positions of downflow intrusions in the penumbra in the upper chromosphere (see Fig. 4d).