Spatial comparison between brightness temperature dynamics in ALMA and SDO/HMI magnetogram. (a) The time-averaged SDO/HMI magnetogram for the whole ALMA FOV is presented as blue, white, and red shades with the value range saturated at [ − 160, 160] G. The absolute LOS magnetic field strength is outlined with gray contour lines with the levels 10, 30, 80, and 120 G. The green dotted-dashed lines mark the mask defining the borders between network and internetwork regions. The dotted ring marks the radial distance of 15″ from the center of the FOV. The spatial positions of the selected events A–D (Sect. 3.4 and Appendix B) are marked for reference. (b) The spatial position of all instances in the entire FOV with a T_b excess of more than 400 K and a lifetime shorter than 200 s, at any time in the data, are marked with orange-brown dots. The white spaces are therefore locations without any events and a single pixel can show several T_b instances. The gray contour outlines the SDO/HMI magnetogram, whereas the green dotted-dashed contours, the dotted ring, and the crosses A–D mark the same as in panel a. (c) Histograms of the absolute LOS magnetic field strength at the locations and times of the T_b peaks marked in panel b (orange-brown) and for the entire HMI data set (blue). The inset plot shows the ratio of the two histograms.