Properties of MFLs with different ΔB. Top left: field lines with ΔB < 0 G (turquoise), 0–400 G (red), 400–800 G (yellow), and > 800 G (green) in a top view overlaid on B_z. Bottom left: same in a side view to highlight the shape. Top right: inner and outer FPs for the same ranges in ΔB. Bottom right: scatter plot of ΔB and 3D loop length. The map in the bottom left panel is rotated relative to the images in the top row for better visibility of the closed MFLs.