Archive | 2021
Ice clouds detection with NOMAD-LNO onboard ExoMars Trace Gas Orbiter
Abstract
<p>This work takes advantage of the NOMAD spectrometer observations, on board the 2016 ExoMars Trace Gas Orbiter. ExoMars is an ESA-Roscosmos joint mission consisting of a rover and an orbiter (Trace Gas Orbiter - TGO). The Nadir and Occultation for Mars Discovery (NOMAD) is one of the four instruments on board TGO. The instrument is a suite of three spectrometers designed to observe the atmosphere and the surface of Mars in the UV, visible and IR. For this study, the Limb, Nadir and Occultation (LNO) channel, operating in the IR, is selected [1][2].  We focus on specific signatures in the [2.3 - 3.8 μm] range of NOMAD-LNO in order to study the possible detection of clouds at these wavelengths in the infrared.</p><p>For this study, we have selected the order 169 ([2611.8 nm - 2632.7 nm]) located in the vicinity of 2.7 µm CO<sub>2</sub>/H<sub>2</sub>O ices absorption band. We search for the presence of ice clouds in MY 34 (L<sub>S </sub>= 150° - 360°) and MY 35 for observations with a solar zenith angle below 80 degrees.  The detection method is adapted from Bellucci et al., 2019 [3] and L. Ruiz Lozano et al., 2020 [4].  The initial results indicate a number of detections in the Tharsis region consistent with the known ‘W’ clouds [6][7].  Finally, these results will be compared with the NOMAD-UVIS observations ([230 nm - 310 nm]) obtained at the same TGO orbits.</p><p><strong>Acknowledgements<br></strong></p><p>The NOMAD experiment is led by the Royal Belgian Institute for Space Aeronomy (IASB-BIRA), assisted by Co-PI teams from Spain (IAA-CSIC), Italy (INAF-IAPS), and the United Kingdom (Open University). This project acknowledges funding by the Belgian Science Policy Office (BELSPO), the Belgian Fonds de la Recherche Scientifique – FNRS under grant number 30442502 (ET_HOME) and the FRIA, with the financial and contractual coordination by the ESA Prodex Office (PEA 4000103401, 4000121493), by Spanish Ministry of Science and Innovation (MCIU) and by European funds under grants PGC2018-101836-B-I00 and ESP2017-87143-R (MINECO/FEDER), as well as by UK Space Agency through grants ST/R005761/1, ST/P001262/1, ST/R001405/1 and ST/R001405/1 and Italian Space Agency through grant 2018-2-HH.0.</p><p> </p><p><strong>References</strong><br>[1] A.C. Vandaele et al., 2015. Optical and radiometric models of the NOMAD instrument part I: the UVIS channel. Optics Express, 23(23):30028–30042.<br>[2] E. Neefs et al., 2015. NOMAD spectrometer on the ExoMars trace gas orbiter mission: part 1—design, manufacturing and testing of the infrared channels. Applied optics, 54(28):8494–8520.<br>[3] G. Bellucci et al., 2019. TGO/NOMAD Nadir observations during the 2018 global dust storm event, EPSC-DPS 2019<br>[4] L. Ruiz Lozano et al., 2020. Use of TGO-NOMAD nadir observations for ice detection, EPSC Abstracts, Vol. 14, Virtual EPSC 2020, EPSC2020-748. <br>[5] M. Vincendon, et al., 2011. New near‐IR observations of mesospheric CO2 and H2O clouds on Mars, J. Geophys. Res., 116, E00J02, doi:10.1029/2011JE003827.<br>[6] J. L. Benson, et al., 2003. The seasonal behavior of water ice clouds in the Tharsis and Valles Marineris regions of Mars: Mars Orbiter Camera Observations, Icarus, Volume 165, Issue 1, 2003, Pages 34-52, ISSN 0019-1035, https://doi.org/10.1016/S0019-1035(03)00175-1.</p>