Relationship between the non-potentiality N_max and distribution of CS and the line integral of the B_z gradient across the PIL on the magnetogram. A: diamond represents magnetic energies, and black, blue, and green represent the potential energy, open field energy, and free magnetic energy, respectively. Red solid circle represents non-potentiality, N_max. The three dashed vertical lines represent the values of three different parameters σ_y (with σ_x = 2.0 and y_c = 0.8 fixed). Magenta, cyan, and gold represent σ_y = 0.5, 0.7, and 0.8, respectively. B: black squares represents the maximum current density and the red solid curves represents the height of the maximum current density.