Molecular Oxygen Mixing Ratio and Its Seasonal Variability in the Martian Atmosphere

The mixing ratio of molecular oxygen and other species that do not condense at martian ambient conditions will vary as the mass of atmosphere oscillates over a martian year due to alternate condensation and vaporization of carbon dioxide at the poles. This variation can be estimated utilizing measurements of mixing ratio made in-situ together with multi-year measurements of atmospheric pressure, both available from the Viking landers starting in 1976. The concentration of non-condensables, on average, will be approximately an inverse function of the atmospheric pressure.