(a) Evolution of AR 10268 magnetic flux. The dotted-red (blue) line shows the evolution of the positive (negative) magnetic flux of the square selection of the magnetogram (as shown in Fig. 1). Solid-red and dashed-blue lines are the positive and negative flux, respectively, computed over the AR field (see Fig. 3c as example). The black line shows the evolution of the most probable model magnetic flux (positive plus absolute value of the negative fluxes divided by two). (b) Estimated value for the standard deviation between model and observations using Eq. (5) over the AR field. The red-solid (blue-dashed) line corresponds to σ_est for the positive (negative) polarity. The black line corresponds to σ_est for points within the AR region (|B_+, j|≥1 G).