Variation of correlation coefficients and power-law indices from photosphere to temperature minimum. Using the Mg II wing this plot fills the gap between the formation region of AIA 1600 Å and Mg II k1r in Figs. 5 and 7. Panel a: Spearman correlation and Panel b: power-law index of the relation of the emission to the magnetic field. The asterisks show results based on the emission in 0.5 Å wide bands in the red wing of Mg II h. The formation height increases with decreasing wavelength (i.e. to the right). These data are based on the active region set with a spatial scale of 1.5″, thus the black filled circles show the same data points as the black filled circles for AIA 1600 Å and Mg II k1r in Figs. 5 and 7. See Sect. 5.2.