Annual mean mixing ratios of N-2, Ar, O-2, and CO in the martian atmosphere

摘要

The precise mixing ratios of N-2, Ar, O-2, and CO measured by the MSL Curiosity quadrupole mass spectrometer must be corrected for the seasonal variations of the atmospheric pressure to reproduce annual mean mixing ratios on Mars. The corrections are made using measurements for the first year of the Viking Landers 1 and 2 and the Mars Climate Database data. The mean correction factor is 0.899 +/- 0.006 resulting in annual mean mixing ratios of (1.83 +/- 0.03)% for N-2, (1.86 +/- 0.02)% for Ar, (1.56 +/- 0.06) x 10(-3) for O-2, and 673 +/- 2.6 ppm for CO. The O-2 mixing ratio agrees with the Herschel value within its uncertainty, the ground-based observations corrected for the dust extinction, and photochemical models by Nair et al. (1994) and Krasnopolsky (2010). The CO mixing ratio is in excellent agreement with the MRO/CRISM value of 700 ppm and with 667, 693, and 684 ppm recently observed at L-s = 60, 89, and 110 degrees and corrected to the annual mean conditions. Lifetimes of N-2 and Ar are very long in the martian atmosphere, and differences between the MSL and Viking data on these species cannot be attributed to their variations.