First Detection Of Ozone In The Mid-infrared At Mars: Implications For Methane Detection

Spectra recorded by ACS MIR at 5.5 km using secondary grating position 12 during occultation 2476 N1 on Ls = 192.7◦: a) contributions from O3, H2O, and CO2 to the best-fit for orders 180–182; b) data and best-fits for orders 180–182.

The ExoMars Trace Gas Orbiter (TGO) was sent to Mars in March 2016 to search for trace gases diagnostic of active geological or biogenic processes.

We report the first observation of the spectral features of Martian ozone (O3) in the mid-infrared range using the Atmospheric Chemistry Suite (ACS) Mid-InfaRed (MIR) channel, a cross-dispersion spectrometer operating in solar occultation mode with the finest spectral resolution of any remote sensing mission to Mars. Observations of ozone were made at high northern latitudes (>65N) prior to the onset of the 2018 global dust storm (Ls = 163-193).

During this fast transition phase between summer and winter ozone distribution, the O3 volume mixing ratio observed is 100-200 ppbv near 20 km. These amounts are consistent with past observations made at the edge of the southern polar vortex in the ultraviolet range. The observed spectral signature of ozone at 3000-3060 cm-1 directly overlaps with the spectral range of the methane (CH4) nu3 vibration-rotation band, and it, along with a newly discovered CO2 band in the same region, may interfere with measurements of methane abundance.

Kevin S. Olsen, Franck Lefèvre, Franck Montmessin, Alexander Trokhimovskiy, Lucio Baggio, Anna Fedorova, Juan Alday, Alexander Lomakin, Denis A. Belyaev, Andrey Patrakeev, Alexey Shakun, Oleg Korablev
Comments: 7 pages, 6 figures
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Atmospheric and Oceanic Physics (
DOI: 10.1051/0004-6361/202038125
Cite as: arXiv:2006.09079 [astro-ph.EP] (or arXiv:2006.09079v1 [astro-ph.EP] for this version)
Submission history
From: Kevin Olsen
[v1] Tue, 16 Jun 2020 11:24:44 UTC (284 KB)

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