Two-dimensional histograms of the WFA vs. MHS magnetic field for B_∥ (left) and B_⊥ (right) for the overlapping part of the FOV shown in Fig. 2 (i.e. excluding pixels without Ca II data). The diagonal blue line indicates a 1:1 relation, and the dashed red line shows a linear fit to the data. The numbers between parantheses indicate the respective Pearson correlation coefficients.