Active region from IRIS raster scan and magnetic field context from HMI. The images display the active region 11850 (cf. Table 1). Panel a: the SDO/HMI line-of-sight magnetogram and the raster maps by IRIS in (panel b)Mg II k1r, (panel c)Mg II k3, and (panel d)Si IV. The lines and contours highlight the regions used to define the active region and plage areas (see Sect. 2.3). The three yellow rectangles indicate the location of pores and sunspots, the large red rectangle the full extent of the active region. The green contours (only in panel b) show the location of the plage area. The threshold for the definition of the plage area was calculated in the orange rectangle indicating a quiet region.