Evolution of the external Gauss coefficients (Eq. (18)) during one CME as a function of time (minutes) for planetary magnetic field strength: B_p = 0 (top), 0.03 (upper middle), 0.07 (lower middle), and 0.21 G (bottom). The left column shows DP; the right column shows FR model results. Displayed are all considered external Gauss coefficients ($q_l^m$ and $s_l^m$) up to quadrupolar degree (l = 2).