Structure of the dayside Martian upper atmosphere and incident solar spectrum adopted for the MAVEN DD2 conditions in the nominal model simulation. (a) Colored solid lines show the fixed density profiles of the six background species (CO₂, O, CO, N₂, Ar, and He). Dashed lines represent the self-consistently solved density profiles of O₂ and H₂O with fixed lower-boundary mixing ratios (see also Figure 6). The black solid line denotes the prescribed neutral temperature profile T_n (refer to the top axis). (b) Incident solar EUV and SXR spectrum used in the simulations, obtained from the Earth-based FISM-2 solar spectral irradiance model for the DD2 period and scaled to the heliocentric distance of Mars.