a) Evolutions of the 171 Å flux (normalized as in Fig. 2) and the unsigned vertical electric current I_z, which is integrated in the field of view as shown in Fig. 4. Blue stars mark the normalized 171 Å flux and red diamonds mark the unsigned vertical electric current I_z. b) The electric current evolution curves at the first and third peaks have been shifted to the second peak, and the total profile is shown with a continuous line. The shifted time differences are t₂ − t₁ and t₃ − t₂ for the two curves (denoted by dashed and dash-dotted lines), respectively. We note that the vertical axes for both the 171 Å flux and I_z do not start from zero.