Impact of Solar Wind Density and Velocity on Martian Ion Escape: A Study Using the Dynamic Box Method

Ion escape is a key mechanism driving the long‐term atmospheric evolution of Mars, and variations in solar wind conditions significantly influence ion escape rates. However, the different responses of various ion species within plume and tailward escape channels under varying solar wind velocities and densities remain poorly understood, hindering a comprehensive understanding of Martian atmospheric loss processes. To address this issue, we employ a three‐dimensional multifluid MHD model to systematically simulate the escape behaviors of three major heavy ion species (O + , O 2 + , and CO 2 + ) under different solar wind conditions. We propose a novel dynamic channel separation method based on the location of the magnetic pile‐up boundary, which enables an accurate distinction between plume and tailward escape regions. This approach allows for a more precise assessment of escape rates, channel contributions, and energy spectra by ion species. Simulation results show that: (a) the total escape rates of all three ions increase significantly with rising solar wind density and velocity, with tailward escape showing a steeper increase. (b) As solar wind density increases, O 2 + replaces O + as the dominant escaping ion. Although CO 2 + exhibits the lowest total escape rate, it shows the highest sensitivity to solar wind variations. (c) Energy spectral analysis reveals clear differences between the two escape channels. Plume escape ions generally have higher energies, with O + more energetic than O 2 + and CO 2 + . In contrast, the energy of escaping ions shows a positive correlation with ion mass in the tailward escape channel.