Dependence of the MPB model parameters r₀ (square in panel a), α₀ (circle in panel b), α₁ (gradient in panel c), and α₂ (delta in panel d) on the solar wind dynamic pressure P_d corresponding to the different solar wind number density n. The IMF conditions are B_X = −1.6776 nT, B_Y = 2.4871 nT, and B_Z = 0 nT. The line segments connect adjacent points. The colors red, green, black, cyan, and blue represent n = 1, 3, 5, 7, and 9 cm⁻³, respectively. Further details of the simulations and fits are listed as cases 13–47 in the supplementary document.