Field line geometrical structures of best-fit ASS GMF models in the (x, y, z = 0) and (x, y = 0, z) planes of the Galaxy for the three best-fit n_d models obtained from the adjustment of the I₃₅₃ map. From left to right: with n_d ≡ ED, ARM4 and ARM4⊕ED, respectively.The color scale indicates the strength of GMF, i.e. the norm of the vector field at each location, which is fixed to 2.1 in the case of the ASS model.