Species‐Dependent Tidal Effects on Ions in the Martian Upper Atmosphere

Atmospheric tides drive large‐scale variability in the Martian ionosphere, but their effect on ionospheric composition remains unclear. Using measurements from the Neutral Gas and Ion Mass Spectrometer (NGIMS) onboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, we examine tidal signatures in the major ions and , with emphasis on species‐dependent behavior and chemical coupling. Harmonic analysis of zonal wavenumbers 1–3 reveals strong tidal amplitudes, up to ∼30%, between 150 and 200 km, with clear dependence on altitude, spatial scale, and season. Similar variability in the ion ratio suggests that tides may influence ionospheric composition beyond simple vertical displacements. The observed correspondence between tidal variations in the neutral O/ ratio and in / is consistent with a chemically mediated coupling, in which tide‐driven neutral composition changes may alter the balance between and . Minor ions also display species‐ and season‐dependent tidal responses, indicating that chemical and dynamical factors likely contribute to their variability. Overall, atmospheric tides influence the Martian ionosphere through coupled dynamical and photochemical processes, highlighting the key role of chemistry in ionosphere‐thermosphere coupling.