Hα images before (left), during (middle) and after (right) the heating episode with overplotted the ±50 G magnetic-field contours (red – positive polarity, blue – negative). The images are produced by summing the Hα intensity in the blue and red wings of Hα at ±0.45 Å. The large square denoted as R5 in the left panel is where the temporal variations from the whole CBP shown in Figs. 5 and 7 were obtained. A cross denotes R3, from which the temporal variations in one of the HLs were produced in Figs. 5 and 7. The pixel size is 0.16″.