3D rendering of the current and magnetic field lines around the loop in a top view from above the active region of Chen et al. (2014, 2015). The colored plane at the bottom shows the vertical current J_z at z = 2.9 Mm at the base of the corona; the color-coding and scale are similar to those in Fig. 5a for the same quantity at the same height. The gray-colored lines display the magnetic field lines connecting the positive and negative vertical current concentrations with each other. The red line shows a current line (or a streamline of the vector field of the current) connecting the positive vertical current concentration on the right-hand side to the negative concentration on the left-hand side. The yellow line also shows a current line, but connecting the positive and negative current concentrations on the right-hand side. We refer to Sect. 3.2.