Retrievals of dust and ozone from NOMAD-UVIS
- 1Belgian Institute for Space Aeronomy (BIRA-IASB), Planetary Aeronomy, Uccle, Brussels, Belgium (arianna.piccialli@aeronomie.be)
- 2Open University, UK
- 3INAF, Istituto di Astrofisica e Planetologia Spaziali, Italy
- 4IAA/CSIC, Granada, Spain
We will present two years of observation of dust and ozone vertical distribution obtained from NOMAD-UVIS solar occultations.
Atmospheric aerosols are ubiquitous in the Martian atmosphere and they strongly affect the Martian climate [1]. This is particularly true during dust storms. In June 2018, after a pause of 11 years, a planet-encircling dust storm took place on Mars that lasted two months.
Ozone, on the other hand, is a species with a short chemical lifetime and characterized by sharp gradients at the day-night terminator due to photolysis [2]. Odd hydrogen radicals play an important role in the destruction of ozone. This results in a strong anti-correlation between O3 and H2O [2].
The NOMAD (Nadir and Occultation for MArs Discovery) – operating onboard the ExoMars 2016 Trace Gas Orbiter satellite – started to acquire the first scientific measurements on 21 April 2018.
It is a spectrometer composed of 3 channels: 1) a solar occultation channel (SO) operating in the infrared (2.3-4.3 μm); 2) a second infrared channel LNO (2.3-3.8 μm) capable of doing nadir, as well as solar occultation and limb; and 3) an ultraviolet/visible channel UVIS (200-650 nm) that can work in the three observation modes [3,4]. The UVIS channel has a spectral resolution <1.5 nm. In the solar occultation mode it is mainly devoted to study the climatology of ozone and aerosols content [5].
Since the beginning of operations, on 21 April 2018, NOMAD-UVIS acquired more than 3000 solar occultations with a complete coverage of the planet. NOMAD-UVIS spectra are simulated using the line-by-line radiative transfer code ASIMUT-ALVL developed at IASB-BIRA [6]. In a preliminary study based on SPICAM-UV solar occultations (see [7]), ASIMUT was modified to take into account the atmospheric composition and structure at the day-night terminator. As input for ASIMUT, we used gradients predicted by the 3D GEM-Mars v4 Global Circulation Model (GCM) [8,9].
NOMAD will help us improve our knowledge of the climatology of ozone and aerosols. In particular, we will have the rare opportunity to analyze the distribution of aerosols during a dust storm.
References:
[1] Määttänen, A., Listowski, C., Montmessin, F., Maltagliati, L., Reberac, A., Joly, L., Bertaux, J.L., Apr. 2013. Icarus 223, 892–941.
[2] Lefèvre, F., et al., Aug. 2008. Nature 454, 971–975.
[3] Vandaele, A.C., et al., Planetary and Space Science, Vol. 119, pp. 233–249, 2015.
[4] Neefs, E., et al., Applied Optics, Vol. 54 (28), pp. 8494-8520, 2015.
[5] M.R. Patel et al., In: Appl. Opt. 56.10 (2017), pp. 2771–2782. DOI: 10.1364/AO.56.002771.
[6] Vandaele, A.C., et al., JGR, 2008. 113 doi:10.1029/2008JE003140.
[7] Piccialli, A., Icarus, in press, https://doi.org/10.1016/j.icarus.2019.113598.
[8] Neary, L., and F. Daerden (2018), Icarus, 300, 458–476, doi:10.1016/j.icarus.2017.09.028.
[9] Daerden et al., 2019, Icarus 326, https://doi.org/10.1016/j.icarus.2019.02.030
How to cite: Piccialli, A., Vandaele, A. C., Willame, Y., Depiesse, C., Trompet, L., Neary, L., Viscardy, S., Daerden, F., Thomas, I. R., Ristic, B., Mason, J. P., Patel, M., Bellucci, G., and Lopez Moreno, J. J.: Retrievals of dust and ozone from NOMAD-UVIS, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16039, https://doi.org/10.5194/egusphere-egu2020-16039, 2020.
