Ground-based infrared measurements of the global distribution of ozone in the atmosphere of Mars

We report measurements of the global distribution of ozone in the atmosphere of Mars, based on Doppler-limited infrared spectroscopy during the period 3–7 June 1988. The Martian spectrum was measured in the region of the P36 transition of 12C 16O 2 (1031.4774 cm −1) in a search for two O 3 lines arising in the ν 3 band at 1031.4515 and 1031.4559 cm −1. Surface pressures and temperature profiles were retrieved by inversion of the fully resolved 12C 16O 2 line. Ozone measurements were obtained at eight beam positions over a range of Martian latitudes (80° S to 20° N) and local solar hour angles (−0.5 h to +5.5 h). The total O 3 column abundance at each position was retrieved by fitting the lines with synthetic spectra generated by a radiative transfer program. The only previous ozone measurement at this season ( L s ∼ 204°) was made above the south polar cap by Mariner 7 and revealed an abundance of 10 μm-atm. However, the retrieved O 3 column burdens of this investigation are less than 2.2 μm-atm for all latitudes sampled, consistent with seasonal abundances predicted by the models of Liu and Donahue, and Shimazaki and Shimizu.