Comparison between the CR ionisation rate distribution obtained by using the fitting formula (Eq. (16)) from Umebayashi & Nakano (2009) considering rectilinear propagation, black contours, and Eq. (5), white contours, for rectilinear propagation (left panels) and following the path of CRs along field lines with the inclusion of mirroring and focusing effects (right panels). The three concentric black contours in all the panels as well as the white contours in the left panels refer to log ₁₀  (ζ^H₂/s^-1) = −17.5, −18, −21 going inwards. Labels are on a logarithmic scale and the colour coding shows the density distribution. Upper panels: model C; lower panels: model E of Table 1.