The panels a)–d) show the correlation analysis that tests for the dependence of the non-dimensional expansion factor ζ (Eq. (5)) on other MC parameters. The drawing convention is the same as in Fig. 4. Both S_1 AU and ⟨B⟩_1 AU are normalized to 1 AU using the size and field strength dependence on the distance, according to the relationship given in Fig. 4 for non-perturbed MCs, see Eq. (8).