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Three Mars Years (almost) of ozone vertical profiles from the ExoMars TGO NOMAD spectrometer

Presentation #307.06 in the session Characterizing the Martian Atmosphere, All the Way Up (Oral Presentation)

Published onOct 23, 2023
Three Mars Years (almost) of ozone vertical profiles from the ExoMars TGO NOMAD spectrometer

The ExoMars Trace Gas Orbiter has been conducting science operations since April 2018, and carries the Nadir and Occultation for Mars Discovery (NOMAD) instrument. NOMAD is a three-channel spectrometer suite, which includes the Ultraviolet and Visible Spectrometer (UVIS) channel, designed to map the vertical profile and column abundances of ozone and dust/ice aerosols in the atmosphere of Mars. Here we present observations of the vertical distribution of ozone (and comparisons to water vapour) from LS = 163° in MY34 to the present-day. Representing almost 3 Mars Years of continuous observations, the NOMAD-UVIS observations of ozone profiles now provide a vast dataset from which long-term studies of ozone (and thus odd-hydrogen species, HOx) chemistry can be conducted. Here, we present the interannual variability of the vertical distribution of ozone, showing the difference in distribution of ozone at mid- and low-altitudes during non-global dust storm years, and a comparison of high-altitude ozone distribution in response to a global dust storm. We present an analysis of the variability of the high-altitude layer detected in previous Mars Years, and present the multi-year ozone vertical distribution in combination with existing water vapour profiles. The observed vertical distribution of ozone is compared with global climate model simulations of expected ozone abundance. We find that, in spite of assimilating water vapour profiles to give the best possible model representation of the water cycle, ozone abundance is still not accurately represented in global climate models, indicating a gap in our knowledge relating to the chemical interaction of these species in the atmosphere of Mars. The multi-year dataset of ozone (and water vapour) that the NOMAD instrument has acquired now provides the ideal opportunity to develop a deeper understanding of the HOx chemistry occurring in the atmosphere of Mars.

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