LP and CP maps from SST/CRISP data at 09:31 UT (top panels) and 08:52 UT (bottom panels) on September 4 and 5, respectively. The boxes drawn on the CP maps indicate where the magnetic flux evolution shown in Fig. 8 has been computed. The LP and CP maps are scaled to 0.05 LP/I_c and ±0.05 CP/I_c, respectively. The colored symbols (I−IV) in LP panels refer to locations considered in Fig. 10. See Sect. 3.2 for more details.