Magnetic flux vs. time at jet’s footpoint. Magnetic flux of positive (panel a) and negative (panel b) polarity magnetic concentrations within the footpoint region of the jet (white box in Fig. 3d) for pixels stronger than 10 G are shown. The dotted vertical lines mark the start and stop times for the entire observation period of the IRIS slit-jaws: 07:13:15–07:44:58 UT. The solid vertical lines mark the period when the raster is scanning across the jet: 07:21:43–07:25:46 UT. The SJI1400 frame wherein the jet is seen occurs at 07:21:43 UT. In panel a, the black line shows the linear trend. The gray shading covers the root-mean-square error (rmsE) from this fit. Panel b shows the root-mean-square (rms) and the rmsE for the calculated values from the rms by the black horizontal line and the gray shading, respectively. See Sects. 3.3 and 4.3.