Solar wind dynamic pressure dependence on the subsolar standoff distance of the Martian MPB. Panel a: r₀ identified from the simulation data for the solar wind number density n = 1 (blue), 3 (cyan), 5 (black), 7 (green), and 9 (red) cm⁻³. The solid line segments connect adjacent points. Panel b: fitting results by the exponential function (solid cyan line), by the power-law relations considering P_d alone, (solid red line), and n and V individually, r₀(R_M) = cn^−1∕d|V |^−2∕e (dashed lines). The dashed blue, green, and black lines represent the fitting results for V = −300, −500, and −700 km s⁻¹, respectively.