Total column ozone climatology from MY34 to MY36 from measurements by the NOMAD-UVIS spectrometer

Mason, Jonathon; Patel, Manish; Holmes, James; Streeter, Paul; Alday, Juan; Brown, Megan; Sellers, Graham; Marriner, Charlotte; Lewis, Stephen; Wolff, M. J.; Williame, Y.; Depiesse, C.; Ristic, B.; Thomas, I.; Daerden, F.; Vandaele, A. C.; Lopez-Moreno, J.-J. and Bellucci, G. (2022). Total column ozone climatology from MY34 to MY36 from measurements by the NOMAD-UVIS spectrometer. In: 7th Mars Atmosphere Modelling and Observations workshop, 14-17 Jun 2022, Paris, France.


Near continuous radiance measurements of the martian atmosphere in the 200-650 nm wavelength range by the Ultraviolet and VISible spectrometer (UVIS) (Patel et al., 2017) as part of the NOMAD instrument on the ExoMars Trace Gas Orbiter (TGO) (Vandaele, et al., 2018) provides a powerful tool for investigating the ozone climatology, the water cycle (from the well established photochemical anti-correlation between water vapour and ozone), and by extension photochemical reactions in the martian atmosphere. Previous observations have shown that, spatially, ozone is observed in three main regions (1) at high northern latitudes (50° - 90° N) through the northern autumn, winter and spring seasons, (2) at equivalent high southern latitudes during the aphelion season, and (3) at low latitudes between 30°S - 30°N from Ls = 30° - 120°, coinciding with observations of the aphelion cloud belt (Bertaux et al., 2000; Clancy et al., 2016; Holmes et al., 2018). Entrapment of ozone in deep depressions, such as Hellas basin (Clancy et al., 2016), has been observed and associated with the meridional transport of O-rich air from northern latitudes and from south polar air being transported to equatorial regions after southern winter. In this study, radiative transfer modelling, that includes multiple scattering from aerosols and surface reflectance, has been used to model the UVIS radiances in the wavelength range 220-310 nm to retrieve the O3 column abundances for the latter half of Mars Year (MY)34 through MY36. We report the spatial distribution of ozone as measured by UVIS, including the observed entrapment and diurnal cycle of ozone within Hellas basin.

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