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1. Machine Learning for automatic identification of new minor species

Author

Schmidt, Frederic, Mermy, Guillaume Cruz, Erwin, Justin, Robert, Severine, Neary, Lori, Thomas, Ian R., Daerden, Frank, Ristic, Bojan, Patel, Manish R., Bellucci, Giancarlo, Lopez-Moreno, Jose-Juan, and Vandaele, Ann-Carine

Subjects
Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Computer Science - Machine Learning
Abstract

One of the main difficulties to analyze modern spectroscopic datasets is due to the large amount of data. For example, in atmospheric transmittance spectroscopy, the solar occultation channel (SO) of the NOMAD instrument onboard the ESA ExoMars2016 satellite called Trace Gas Orbiter (TGO) had produced $\sim$10 millions of spectra in 20000 acquisition sequences since the beginning of the mission in April 2018 until 15 January 2020. Other datasets are even larger with $\sim$billions of spectra for OMEGA onboard Mars Express or CRISM onboard Mars Reconnaissance Orbiter. Usually, new lines are discovered after a long iterative process of model fitting and manual residual analysis. Here we propose a new method based on unsupervised machine learning, to automatically detect new minor species. Although precise quantification is out of scope, this tool can also be used to quickly summarize the dataset, by giving few endmembers ("source") and their abundances. We approximate the dataset non-linearity by a linear mixture of abundance and source spectra (endmembers). We used unsupervised source separation in form of non-negative matrix factorization to estimate those quantities. Several methods are tested on synthetic and simulation data. Our approach is dedicated to detect minor species spectra rather than precisely quantifying them. On synthetic example, this approach is able to detect chemical compounds present in form of 100 hidden spectra out of $10^4$, at 1.5 times the noise level. Results on simulated spectra of NOMAD-SO targeting CH$_{4}$ show that detection limits goes in the range of 100-500 ppt in favorable conditions. Results on real martian data from NOMAD-SO show that CO$_{2}$ and H$_{2}$O are present, as expected, but CH$_{4}$ is absent. Nevertheless, we confirm a set of new unexpected lines in the database, attributed by ACS instrument Team to the CO$_{2}$ magnetic dipole., Comment: 26 pages, 10 figures

Published
2020
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2. Atmospheric Escape Processes and Planetary Atmospheric Evolution

Author

Gronoff, Guillaume, Arras, Phil, Baraka, Suleiman M, Bell, Jared M, Cessateur, Gaël, Cohen, Ofer, Curry, Shannon M., Drake, Jeremy J, Elrod, Meredith K, Erwin, Justin T., Garcia-Sage, Katherine, Garraffo, Cecilia, Glocer, Alex, Heavens, Nicholas Gray, Lovato, Kylie, Maggiolo, Romain, Parkinson, Christopher D., Wedlund, Cyril L. Simon, Weimer, Daniel R, and Moore, William B.

Subjects
Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Solar and Stellar Astrophysics, Physics - Space Physics
Abstract

The habitability of the surface of any planet is determined by a complex evolution of its interior, surface, and atmosphere. The electromagnetic and particle radiation of stars drive thermal, chemical and physical alteration of planetary atmospheres, including escape. Many known extrasolar planets experience vastly different stellar environments than those in our Solar system: it is crucial to understand the broad range of processes that lead to atmospheric escape and evolution under a wide range of conditions if we are to assess the habitability of worlds around other stars. One problem encountered between the planetary and the astrophysics communities is a lack of common language for describing escape processes. Each community has customary approximations that may be questioned by the other, such as the hypothesis of H-dominated thermosphere for astrophysicists, or the Sun-like nature of the stars for planetary scientists. Since exoplanets are becoming one of the main targets for the detection of life, a common set of definitions and hypotheses are required. We review the different escape mechanisms proposed for the evolution of planetary and exoplanetary atmospheres. We propose a common definition for the different escape mechanisms, and we show the important parameters to take into account when evaluating the escape at a planet in time. We show that the paradigm of the magnetic field as an atmospheric shield should be changed and that recent work on the history of Xenon in Earth's atmosphere gives an elegant explanation to its enrichment in heavier isotopes: the so-called Xenon paradox.

Published
2020
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3. Strong variability of Martian water ice clouds during dust storms revealed from ExoMars Trace Gas Orbiter/NOMAD

Author

Liuzzi, Giuliano, Villanueva, Geronimo L., Crismani, Matteo M. J., Smith, Michael D., Mumma, Michael J., Daerden, Frank, Aoki, Shohei, Vandaele, Ann Carine, Clancy, R. Todd, Erwin, Justin, Thomas, Ian, Ristic, Bojan, Lopez-Moreno, José-Juan, Bellucci, Giancarlo, and Patel, Manish R.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

Observations of water ice clouds and aerosols on Mars can provide important insights into the complexity of the water cycle. Recent observations have indicated an important link between dust activity and the water cycle, as intense dust activity can significantly raise the hygropause, and subsequently increase the escape of water after dissociation in the upper atmosphere. Here present observations from NOMAD/TGO that investigate the variation of water ice clouds in the perihelion season of Mars Year 34 (April 2018-19), their diurnal and seasonal behavior, and the vertical structure and microphysical properties of water ice and dust. These observations reveal the recurrent presence of a layer of mesospheric water ice clouds subsequent to the 2018 Global Dust Storm. We show that this layer rose from 45 to 80 km in altitude on a timescale of days from heating in the lower atmosphere due to the storm. In addition, we demonstrate that there is a strong dawn dusk asymmetry in water ice abundance, related to nighttime nucleation and subsequent daytime sublimation. Water ice particle sizes are retrieved consistently and exhibit sharp vertical gradients (from 0.1 to 4.0 um), as well as mesospheric differences between the Global Dust Storm (<0.5 um) and the 2019 regional dust storm (1.0 um), which suggests differing water ice nucleation efficiencies. These results form the basis to advance our understanding of mesospheric water ice clouds on Mars, and further constrain the interactions between water ice and dust in the middle atmosphere., Comment: Submitted to Journal of Geophysical Research - Planets. 36 pages, 9 figures, 1 table

Published
2019
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5. Calibration of NOMAD on ESA's ExoMars Trace Gas Orbiter: Part 2 – The Limb, Nadir and Occultation (LNO) channel

Author

Thomas, Ian R., Aoki, Shohei, Trompet, Loïc, Robert, Séverine, Depiesse, Cédric, Willame, Yannick, Cruz-Mermy, Guillaume, Schmidt, Frédéric, Erwin, Justin T., Vandaele, Ann Carine, Daerden, Frank, Mahieux, Arnaud, Neefs, Eddy, Ristic, Bojan, Hetey, Laszlo, Berkenbosch, Sophie, Clairquin, Roland, Beeckman, Bram, Patel, Manish R., Lopez-Moreno, Jose Juan, and Bellucci, Giancarlo

Published
2022
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6. Unexpected increase of the deuterium to hydrogen ratio in the Venus mesosphere.

Author

Mahieux, Arnaud, Viscardy, Sébastien, Yelle, Roger Vincent, Hiroki Karyu, Chamberlain, Sarah, Robert, Séverine, Piccialli, Arianna, Trompet, Loïc, Erwin, Justin Tyler, Ubukata, Soma, Hiromu Nakagawa, Shungo Koyama, Maggiolo, Romain, Pereira, Nuno, Cessateur, Gaël, Willame, Yannick, and Vandaele, Ann Carine

Subjects
PHASE transitions, HYDROLOGIC cycle, ISOTOPIC fractionation, MESOSPHERE, WATER vapor
Abstract

This study analyzes H2O and HDO vertical profiles in the Venus mesosphere using Venus Express/Solar Occultation in the InfraRed data. The findings show increasing H2O and HDO volume mixing ratios with altitude, with the D/H ratio rising significantly from 0.025 at ~70 km to 0.24 at ~108 km. This indicates an increase from 162 to 1,519 times the Earth's ratio within 40 km. The study explores two hypotheses for these results: isotopic fractionation from photolysis of H2O over HDO or from phase change processes. The latter, involving condensation and evaporation of sulfuric acid aerosols, as suggested by previous authors [X. Zhang et al., Nat. Geosci. 3, 834-837 (2010)], aligns more closely with the rapid changes observed. Vertical transport computations for H2O, HDO, and aerosols show water vapor downwelling and aerosols upwelling. We propose a mechanism where aerosols form in the lower mesosphere due to temperatures below the water condensation threshold, leading to deuterium-enriched aerosols. These aerosols ascend, evaporate at higher temperatures, and release more HDO than H2O, which are then transported downward. Moreover, this cycle may explain the SO2 increase in the upper mesosphere observed above 80 km. The study highlights two crucial implications. First, altitude variation is critical to determining the Venus deuterium and hydrogen reservoirs. Second, the altitude-dependent increase of the D/H ratio affects H and D escape rates. The photolysis of H2O and HDO at higher altitudes releases more D, influencing long-term D/H evolution. These findings suggest that evolutionary models should incorporate altitude-dependent processes for accurate D/H fractionation predictions. [ABSTRACT FROM AUTHOR]

Published
2024
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7. Comprehensive investigation of Mars methane and organics with ExoMars/NOMAD

Author

Knutsen, Elise W., Villanueva, Geronimo L., Liuzzi, Giuliano, Crismani, Matteo M.J., Mumma, Michael J., Smith, Michael D., Vandaele, Ann Carine, Aoki, Shohei, Thomas, Ian R., Daerden, Frank, Viscardy, Sébastien, Erwin, Justin T., Trompet, Loic, Neary, Lori, Ristic, Bojan, Lopez-Valverde, Miguel Angel, Lopez-Moreno, Jose Juan, Patel, Manish R., Karatekin, Ozgur, and Bellucci, Giancarlo

Published
2021
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10. Molecular-Kinetic Simulations of Escape from the Ex-planet and Exoplanets: Criterion for Transonic Flow

Author

Johnson, Robert E., Volkov, Alexey N., and Erwin, Justin T.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

The equations of gas dynamics are extensively used to describe atmospheric loss from solar system bodies and exoplanets even though the boundary conditions at infinity are not uniquely defined. Using molecular-kinetic simulations that correctly treat the transition from the continuum to the rarefied region, we confirm that the energy-limited escape approximation is valid when adiabatic expansion is the dominant cooling process. However, this does not imply that the outflow goes sonic. In fact in the sonic regime, the energy limited approximation can significantly under estimate the escape rate. Rather large escape rates and concomitant adiabatic cooling can produce atmospheres with subsonic flow that are highly extended. Since this affects the heating rate of the upper atmosphere and the interaction with external fields and plasmas, we give a criterion for estimating when the outflow goes transonic in the continuum region. This is applied to early terrestrial atmospheres, exoplanet atmospheres, and the atmosphere of the ex-planet, Pluto, all of which have large escape rates. The paper and its erratum, combined here, are published: ApJL 768, L4 (2013); ApJ, 779, L30 (2013)., Comment: 11 pages, 3 figures

Published
2013
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11. Hybrid fluid/kinetic modeling of Pluto's escaping atmosphere

Author

Erwin, Justin T., Tucker, O. J., and Johnson, Robert E.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

Predicting the rate of escape and thermal structure of Pluto's upper atmosphere in preparation for the New Horizons Spacecraft encounter in 2015 is important for planning and interpreting the expected measurements. Having a moderate Jeans parameter Pluto's atmosphere does not fit the classic definition of Jeans escape for light species escaping from the terrestrial planets, nor does it fit the hydrodynamic outflow from comets and certain exoplanets. It has been proposed for some time that Pluto lies in the region of slow hydrodynamic escape. Using a hybrid fluid/molecular-kinetic model, we previously demonstrated the typical implementation of this model fails to correctly describe the appropriate temperature structure for the upper atmosphere for solar minimum conditions. Here we use a time-dependent solver to allow us to extend those simulations to higher heating rates and we examine fluid models in which Jeans-like escape expressions are used for the upper boundary conditions. We compare these to hybrid simulations of the atmosphere under heating conditions roughly representative of solar minimum and mean conditions as these bracket conditions expected during the New Horizon encounter. Although we find escape rates comparable to those previously estimated by the slow hydrodynamic escape model, and roughly consistent with energy limited escape, our model produces a much more extended atmosphere with higher temperatures roughly consistent with recent observations of CO. Such an extended atmosphere will be affected by Charon and will affect Pluto's interaction with the solar wind at the New Horizon encounter. Since we have previously shown that such models can be scaled, these results have implications for modeling exoplanet atmospheres for which the energy limited escape approximation is often used., Comment: 13 pages, 5 figures

Published
2012
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12. Thermally-driven atmospheric escape: Transition from hydrodynamic to Jeans escape

Author

Volkov, Alexey N., Johnson, Robert E., Tucker, Orenthal J., and Erwin, Justin T.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

Thermally-driven atmospheric escape evolves from an organized outflow (hydrodynamic escape) to escape on a molecule by molecules basis (Jeans escape) with increasing Jeans parameter, the ratio of the gravitational to thermal energy of molecules in a planet's atmosphere. This transition is described here using the direct simulation Monte Carlo method for a single component spherically symmetric atmosphere. When the heating is predominantly below the lower boundary of the simulation region, R0, and well below the exobase, this transition is shown to occur over a surprisingly narrow range of Jeans parameters evaluated at R0: {\lambda}0 ~ 2-3. The Jeans parameter {\lambda}0 ~ 2.1 roughly corresponds to the upper limit for isentropic, supersonic outflow and for {\lambda}0 >3 escape occurs on a molecule by molecule basis. For {\lambda}0 > ~6, it is shown that the escape rate does not deviate significantly from the familiar Jeans rate evaluated at the nominal exobase, contrary to what has been suggested. Scaling by the Jeans parameter and the Knudsen number, escape calculations for Pluto and an early Earth's atmosphere are evaluated, and the results presented here can be applied to thermally-induced escape from a number of solar and extrasolar planetary bodies., Comment: 16 pages,5 figures

Published
2010
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13. Effective mass of cavity-vibration polaritons formed in etalons with liquid carbon tetrachloride.

Author

Coe, James V. and Erwin, Justin D.

Subjects
*POLARITONS, *MOLECULAR vibration, *LIQUIDS, *CARBON tetrachloride, *PHOTONS
Abstract

Etalons are pairs of parallel plate mirrors with wavelength-scale spacing that exhibit cavity modes, giving transmission maxima (fringes) due to constructive interference. Infrared transmission measurements as a function of angle were used to determine the effective mass of etalon cavity modes using a gap filled with air and then liquid carbon tetrachloride. The air-filled etalon gives results in agreement with pure photon expectations established herein. Liquids with vibrations having strong infrared transition intensity (vibrational strong coupling mode) can strongly perturb the pattern of transmission resonances, creating mixed states of infrared cavity modes and molecular vibrations, i.e., cavity-vibration polaritons. The effective mass of one cavity-vibration polariton close to the strong vibration of carbon tetrachloride is 4.36 times heavier than the pure photon cavity mode expectation, i.e., the mass factor vs pure light. The mass factors are largest when closest to the strong vibrational frequency, and they converge to the one far away from the strong vibration. This work gives quantitative values of the effective mass of cavity-vibration polariton states and is a diagnostic for the mixing of vibrations with etalon transmission. [ABSTRACT FROM AUTHOR]

Published
2022
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14. On the plausibility of methane detections on Mars in the light of the ExoMars/TGO results

Author

Viscardy, Sébastien, Robert, Séverine, Erwin, Justin, Thomas, Ian R., Daerden, Frank, Neary, Lori, Piccialli, Arianna, Trompet, Loïc, Willame, Yannick, and Vandaele, Ann Carine

Abstract

As a potential biomarker, Martian methane has attracted attention through several reports of its detection over the last 20 years. However, the very existence of this gas has been continuously questioned, in particular, because the observed lifetime should be several orders of magnitude shorter than the 300 years predicted by photochemical models. Although several fast removal processes have been hypothesized to explain the observations, none of them has met a large consensus.It is in this context that the ESA-Roscomos ExoMars Trace Gas Orbiter (TGO) mission started its science operations in April 2018. ACS and NOMAD, two instruments onboard the TGO, have been collecting hundreds of highly sensitive measurements in solar occultation. No methane has been detected so far and an upper limit of 0.02 ppbv has been derived.The implications of this result on the methane problem on Mars will be addressed in this work.This upper limit is a strong constraint on the background level and, in turn, on the potential emission scenarios making the reported methane detections consistent with the TGO results. While several model studies aimed at identifying them, we will here adopt a probabilistic approach to the problem in order to question the plausibility of those detections and estimate the lifetime required to make them plausible from a probabilistic standpoint., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Published
2023

15. Martian atmospheric temperature and density profiles during the 1st year of NOMAD/TGO solar occultation measurements

Author

López-Valverde, M. A., Funke, Bernd, Brines, Adrian, Stolzenbach, Aurélien, Modak, Ashimananda, Hill, Brittany, González-Galindo, F., Thomas, Ian R., Trompet, Loic, Aoki, Shohei, Villanueva, Geronimo L., Liuzzi, Giuliano, Erwin, Justin T., Grabowski, Udo, Forget, François, López-Moreno, José Juan, Rodríguez Gómez, Julio, Ristic, Bojan, Daerden, Frank, Bellucci, Giancarlo, Patel, Manish R., Vandaele, Ann Carine, The NOMAD Team, Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), Consejo Superior de Investigaciones Científicas (España), European Commission, European Space Agency, Royal Belgian Institute for Space Aeronomy, Belgian Science Policy Office, UK Space Agency, Agenzia Spaziale Italiana, López-Valverde, M. A., Funke, Bernd, Brines, Adrian, Stolzenbach, Aurélien, Modak, Ashimananda, González-Galindo, F., Thomas, Ian R., Trompet, Loic, Aoki, Shohei, Villanueva, Geronimo L., Liuzzi, Giuliano, Erwin, Justin T., Ristic, Bojan, Daerden, Frank, and Patel, Manish R.

Abstract

We present vertical profiles of temperature and density from solar occultation (SO) observations by the “Nadir and Occultation for Mars Discovery” (NOMAD) spectrometer on board the Trace Gas Orbiter (TGO) during its first operational year, which covered the second half of Mars Year 34. We used calibrated transmittance spectra in 380 scans, and apply an in-house pre-processing to clean data systematics. Temperature and CO2 profiles up to about 90 km, with consistent hydrostatic adjustment, are obtained, after adapting an Earth-tested retrieval scheme to Mars conditions. Both pre-processing and retrieval are discussed to illustrate their performance and robustness. Our results reveal the large impact of the MY34 Global Dust Storm (GDS), which warmed the atmosphere at all altitudes. The large GDS aerosols opacity limited the sounding of tropospheric layers. The retrieved temperatures agree well with global climate models (GCM) at tropospheric altitudes, but NOMAD mesospheric temperatures are wavier and globally colder by 10 K in the perihelion season, particularly during the GDS and its decay phase. We observe a warm layer around 80 km during the Southern Spring, especially in the Northern Hemisphere morning terminator, associated to large thermal tides, significantly stronger than in the GCM. Cold mesospheric pockets, close to CO2 condensation temperatures, are more frequently observed than in the GCM. NOMAD CO2 densities show oscillations upon a seasonal trend that track well the latitudinal variations expected. Results uncertainties and suggestions to improve future data re-analysis are briefly discussed., The IAA/CSIC team acknowledges financial support from the State Agency for Research686of the Spanish MCI through the ‘Center of Excellence Severe Ochoa’ award for the687Instituto de Astrof ́ısica de Andalucia (DEV-2017-0709) and funding by grants688PGC2018-101836-B-100 (MCI/AEI/FEDER, EU),689PID2019-110689RB-I00/AEI/10.13039/501100011033, and RTI2018-100920-J-I00.690ExoMars is a space mission of the European Space Agency (ESA) and Roscosmos. The691NOMAD experiment is led by the Royal Belgian Institute for Space Aeronomy692(IASB-BIRA), assisted by Co-PI teams from Spain (IAA-CSIC), Italy (IN AF-IA PS), and693the United Kingdom (Open University). This project acknowledges funding by the Belgian694Science Policy Office (BELLS), with the financial and contractual coordination by the695ESAU Prod ex Office (PEA 4000103401, 4000121493) as well as by UK Space Agency696through grants ST/V002295/1, ST/V005332/1 and ST/S00145X/1 and Italian Space697Agency through grant 2018-2-HHS.0. US investigators were supported by the National698Aeronautics and Space Administration. This work was supported by the Belgian Funds de699la Recherche Scientific – FIRS under grant number 30442502 (ETHOME). This project700has received funding from the European Union Horizon 2020 research and innovation701program under grant agreement No 101004052 (Road Map project). We want to thank the702LMD and LATMOS teams for the continuous development of the LMD-MGCM.

Published
2022

16. Martian atmospheric temperature and density profiles during the 1st year of NOMAD/TGO solar occultation measurements

Author

Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), Consejo Superior de Investigaciones Científicas (España), European Commission, European Space Agency, Royal Belgian Institute for Space Aeronomy, Belgian Science Policy Office, UK Space Agency, Agenzia Spaziale Italiana, López-Valverde, M. A. [0000-0002-7989-4267], Funke, Bernd [0000-0003-0462-4702], Brines, Adrian [0000-0002-7044-3638], Stolzenbach, Aurélien [0000-0001-6169-6820], Modak, Ashimananda [0000-0002-3915-5531], González-Galindo, F. [0000-0001-9443-291X], Thomas, Ian R. [0000-0003-3887-6668], Trompet, Loic [0000-0001-6259-2054], Aoki, Shohei [0000-0001-6727-125X], Villanueva, Geronimo L. [0000-0002-2662-5776], Liuzzi, Giuliano [0000-0003-3638-5750], Erwin, Justin T. [0000-0003-0200-3195], Ristic, Bojan [0000-0002-9635-1125], Daerden, Frank [0000-0001-7433-1839], Patel, Manish R. [0000-0002-8223-3566], López-Valverde, M. A., Funke, Bernd, Brines, Adrian, Stolzenbach, Aurélien, Modak, Ashimananda, Hill, Brittany, González-Galindo, F., Thomas, Ian R., Trompet, Loic, Aoki, Shohei, Villanueva, Geronimo L., Liuzzi, Giuliano, Erwin, Justin T., Grabowski, Udo, Forget, François, López-Moreno, José Juan, Rodríguez Gómez, Julio, Ristic, Bojan, Daerden, Frank, Bellucci, Giancarlo, Patel, Manish R., Vandaele, Ann Carine, The NOMAD Team, Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), Consejo Superior de Investigaciones Científicas (España), European Commission, European Space Agency, Royal Belgian Institute for Space Aeronomy, Belgian Science Policy Office, UK Space Agency, Agenzia Spaziale Italiana, López-Valverde, M. A. [0000-0002-7989-4267], Funke, Bernd [0000-0003-0462-4702], Brines, Adrian [0000-0002-7044-3638], Stolzenbach, Aurélien [0000-0001-6169-6820], Modak, Ashimananda [0000-0002-3915-5531], González-Galindo, F. [0000-0001-9443-291X], Thomas, Ian R. [0000-0003-3887-6668], Trompet, Loic [0000-0001-6259-2054], Aoki, Shohei [0000-0001-6727-125X], Villanueva, Geronimo L. [0000-0002-2662-5776], Liuzzi, Giuliano [0000-0003-3638-5750], Erwin, Justin T. [0000-0003-0200-3195], Ristic, Bojan [0000-0002-9635-1125], Daerden, Frank [0000-0001-7433-1839], Patel, Manish R. [0000-0002-8223-3566], López-Valverde, M. A., Funke, Bernd, Brines, Adrian, Stolzenbach, Aurélien, Modak, Ashimananda, Hill, Brittany, González-Galindo, F., Thomas, Ian R., Trompet, Loic, Aoki, Shohei, Villanueva, Geronimo L., Liuzzi, Giuliano, Erwin, Justin T., Grabowski, Udo, Forget, François, López-Moreno, José Juan, Rodríguez Gómez, Julio, Ristic, Bojan, Daerden, Frank, Bellucci, Giancarlo, Patel, Manish R., Vandaele, Ann Carine, and The NOMAD Team

Abstract

We present vertical profiles of temperature and density from solar occultation (SO) observations by the “Nadir and Occultation for Mars Discovery” (NOMAD) spectrometer on board the Trace Gas Orbiter (TGO) during its first operational year, which covered the second half of Mars Year 34. We used calibrated transmittance spectra in 380 scans, and apply an in-house pre-processing to clean data systematics. Temperature and CO2 profiles up to about 90 km, with consistent hydrostatic adjustment, are obtained, after adapting an Earth-tested retrieval scheme to Mars conditions. Both pre-processing and retrieval are discussed to illustrate their performance and robustness. Our results reveal the large impact of the MY34 Global Dust Storm (GDS), which warmed the atmosphere at all altitudes. The large GDS aerosols opacity limited the sounding of tropospheric layers. The retrieved temperatures agree well with global climate models (GCM) at tropospheric altitudes, but NOMAD mesospheric temperatures are wavier and globally colder by 10 K in the perihelion season, particularly during the GDS and its decay phase. We observe a warm layer around 80 km during the Southern Spring, especially in the Northern Hemisphere morning terminator, associated to large thermal tides, significantly stronger than in the GCM. Cold mesospheric pockets, close to CO2 condensation temperatures, are more frequently observed than in the GCM. NOMAD CO2 densities show oscillations upon a seasonal trend that track well the latitudinal variations expected. Results uncertainties and suggestions to improve future data re-analysis are briefly discussed.

Published
2022

17. Retrieval of Martian Atmospheric CO Vertical Profiles From NOMAD Observations During the First Year of TGO Operations

Author

Modak, Ashimananda, primary, López‐Valverde, Miguel Angel, additional, Brines, Adrian, additional, Stolzenbach, Aurélien, additional, Funke, Bernd, additional, González‐Galindo, Francisco, additional, Hill, Brittany, additional, Aoki, Shohei, additional, Thomas, Ian, additional, Liuzzi, Giuliano, additional, Villanueva, Gerónimo, additional, Erwin, Justin, additional, Lopez Moreno, José Juan, additional, Yoshida, Nao, additional, Grabowski, Udo, additional, Forget, Francois, additional, Daerden, Frank, additional, Ristic, Bojan, additional, Bellucci, Giancarlo, additional, Patel, Manish, additional, Trompet, Loic, additional, and Vandaele, Ann‐Carine, additional

Published
2023
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18. On the plausibility of methane detections on Mars

Author

Viscardy, Sébastien, primary, Robert, Séverine, additional, Erwin, Justin T., additional, Thomas, Ian R., additional, Daerden, Frank, additional, Neary, Lori, additional, Piccialli, Arianna, additional, Trompet, Loïc, additional, Willame, Yannick, additional, and Vandaele, Ann Carine, additional

Published
2023
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19. Retrieval of Martian Atmospheric CO Vertical Profiles From NOMAD Observations During the First Year of TGO Operations

Author

Ministerio de Ciencia e Innovación (España), European Commission, Belgian Science Policy Office, Modak, Ashimananda, López-Valverde, M. A., Brines, Adrian, Stolzenbach, Aurélien, Funke, Bernd, González-Galindo, F., Hill, Brittany, Aoki, Shohei, Thomas, Ian, Liuzzi, Giuliano, Villanueva, Geronimo L., Erwin, Justin, López-Moreno, José Juan, Yoshida, Nao, Grabowski, Udo, Forget, Francois, Daerden, Frank, Ristic, Bojan, Bellucci, Giancarlo, Patel, Manish, Trompet, Loic, Vandaele, Ann-Carine, Ministerio de Ciencia e Innovación (España), European Commission, Belgian Science Policy Office, Modak, Ashimananda, López-Valverde, M. A., Brines, Adrian, Stolzenbach, Aurélien, Funke, Bernd, González-Galindo, F., Hill, Brittany, Aoki, Shohei, Thomas, Ian, Liuzzi, Giuliano, Villanueva, Geronimo L., Erwin, Justin, López-Moreno, José Juan, Yoshida, Nao, Grabowski, Udo, Forget, Francois, Daerden, Frank, Ristic, Bojan, Bellucci, Giancarlo, Patel, Manish, Trompet, Loic, and Vandaele, Ann-Carine

Abstract

We present CO density profiles up to about 100 km in the Martian atmosphere obtained for the first time from retrievals of solar occultation measurements by the Nadir and Occultation for Mars Discovery (NOMAD) onboard ExoMars Trace Gas Orbiter (TGO). CO is an important trace gas on Mars, as it is controlled by CO2 photolysis, chemical reaction with the OH radicals, and the global dynamics. However, the measurements of CO vertical profiles have been elusive until the arrival of TGO. We show how the NOMAD CO variations describe very well the Mars general circulation. We observe a depletion of CO in the upper troposphere and mesosphere during the peak period, LS = 190°–200°, more pronounced over the northern latitudes, confirming a similar result recently reported by Atmospheric Chemistry Suite onboard TGO. However, in the lower troposphere around 20 km, and at least at high latitudes of the S. hemisphere, NOMAD CO mixing ratios increase over 1,500 ppmv during the GDS (Global Dust Storm) onset. This might be related to the downwelling branch of the Hadley circulation. A subsequent increase in tropospheric CO is observed during the decay phase of the GDS around LS = 210°–250° when the dust loading is still high. This could be associated with a reduction in the amount of OH radicals in the lower atmosphere due to lack of solar insolation. Once the GDS is over, CO steadily decreases globally during the southern summer season. A couple of distinct CO patterns associated with the Summer solstice and equinox circulation are reported and discussed. © 2023. American Geophysical Union. All Rights Reserved.

Published
2023

20. Martian Atmospheric Temperature and Density Profiles During the First Year of NOMAD/TGO Solar Occultation Measurements

Author

Ministerio de Ciencia e Innovación (España), European Commission, Belgian Science Policy Office, UK Space Agency, López-Valverde, M. A., Funke, Bernd, Brines, Adrian, Stolzenbach, Aurélien, Modak, Ashimananda, Hill, Brittany, González-Galindo, F., Thomas, Ian, Trompet, Loic, Aoki, Shohei, Villanueva, Geronimo L., Liuzzi, Giuliano, Erwin, Justin, Grabowski, Udo, Forget, Francois, López-Moreno, José Juan, Rodríguez Gómez, Julio, Ristic, Bojan, Daerden, Frank, Bellucci, Giancarlo, Patel, Manish, Vandaele, Ann-Carine, NOMAD team, Ministerio de Ciencia e Innovación (España), European Commission, Belgian Science Policy Office, UK Space Agency, López-Valverde, M. A., Funke, Bernd, Brines, Adrian, Stolzenbach, Aurélien, Modak, Ashimananda, Hill, Brittany, González-Galindo, F., Thomas, Ian, Trompet, Loic, Aoki, Shohei, Villanueva, Geronimo L., Liuzzi, Giuliano, Erwin, Justin, Grabowski, Udo, Forget, Francois, López-Moreno, José Juan, Rodríguez Gómez, Julio, Ristic, Bojan, Daerden, Frank, Bellucci, Giancarlo, Patel, Manish, Vandaele, Ann-Carine, and NOMAD team

Abstract

We present vertical profiles of temperature and density from solar occultation (SO) observations by the “Nadir and Occultation for Mars Discovery” (NOMAD) spectrometer on board the Trace Gas Orbiter during its first operational year, which covered the second half of Mars Year 34. We used calibrated transmittance spectra in 380 scans, and apply an in-house pre-processing to clean data systematics. Temperature and CO2 profiles up to about 90 km, with consistent hydrostatic adjustment, are obtained, after adapting an Earth-tested retrieval scheme to Mars conditions. Both pre-processing and retrieval are discussed to illustrate their performance and robustness. Our results reveal the large impact of the MY34 Global Dust Storm (GDS), which warmed the atmosphere at all altitudes. The large GDS aerosols opacity limited the sounding of tropospheric layers. The retrieved temperatures agree well with global climate models (GCM) at tropospheric altitudes, but NOMAD mesospheric temperatures are wavier and globally colder by 10 K in the perihelion season, particularly during the GDS and its decay phase. We observe a warm layer around 80 km during the Southern Spring, especially in the Northern Hemisphere morning terminator, associated to large thermal tides, significantly stronger than in the GCM. Cold mesospheric pockets, close to CO2 condensation temperatures, are more frequently observed than in the GCM. NOMAD CO2 densities show oscillations upon a seasonal trend that track well the latitudinal variations expected. Results uncertainties and suggestions to improve future data re-analysis are briefly discussed. © 2022 The Authors. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Published
2023

21. Martian Atmospheric Temperature and Density Profiles During the First Year of NOMAD/TGO Solar Occultation Measurements

Author

NOMAD Team, López-Valverde, Miguel Angel, Funke, Bernd, Brines, Adrian, Stolzenbach, Aurèlien, Modak, Ashimananda, Hill, Brittany, González-Galindo, Francisco, Thomas, Ian, Trompet, Loic, Aoki, Shohei, Villanueva, Gerónimo, Liuzzi, Giuliano, Erwin, Justin, Grabowski, Udo, Forget, Francois, López-Moreno, José Juan, Rodriguez-Gómez, Julio, Ristic, Bojan, Daerden, Frank, Bellucci, Giancarlo, Patel, Manish, Vandaele, Ann-Carine, Ministerio de Ciencia e Innovación (España), European Commission, Belgian Science Policy Office, and UK Space Agency

Subjects
Atmosphere, IAA, KOPRA, Temperature, Mars, Density, ExoMars/TGO, Earth sciences, RCP, Geophysics, IMK-ASF-SAT, Remote sounding, Atmospheric structure, Space and Planetary Science, Geochemistry and Petrology, ddc:550, TGO, Earth and Planetary Sciences (miscellaneous), NOMAD, Planetary atmospheres
Abstract

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited., We present vertical profiles of temperature and density from solar occultation (SO) observations by the “Nadir and Occultation for Mars Discovery” (NOMAD) spectrometer on board the Trace Gas Orbiter during its first operational year, which covered the second half of Mars Year 34. We used calibrated transmittance spectra in 380 scans, and apply an in-house pre-processing to clean data systematics. Temperature and CO2 profiles up to about 90 km, with consistent hydrostatic adjustment, are obtained, after adapting an Earth-tested retrieval scheme to Mars conditions. Both pre-processing and retrieval are discussed to illustrate their performance and robustness. Our results reveal the large impact of the MY34 Global Dust Storm (GDS), which warmed the atmosphere at all altitudes. The large GDS aerosols opacity limited the sounding of tropospheric layers. The retrieved temperatures agree well with global climate models (GCM) at tropospheric altitudes, but NOMAD mesospheric temperatures are wavier and globally colder by 10 K in the perihelion season, particularly during the GDS and its decay phase. We observe a warm layer around 80 km during the Southern Spring, especially in the Northern Hemisphere morning terminator, associated to large thermal tides, significantly stronger than in the GCM. Cold mesospheric pockets, close to CO2 condensation temperatures, are more frequently observed than in the GCM. NOMAD CO2 densities show oscillations upon a seasonal trend that track well the latitudinal variations expected. Results uncertainties and suggestions to improve future data re-analysis are briefly discussed. © 2022 The Authors. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA., The IAA/CSIC team acknowledges financial support from the State Agency for Research of the Spanish MCI through the ‘Center of Excellence Severe Ochoa’ award for the Instituto de Astrofísica de Andalucia (DEV-2017-0709) and funding by grants PGC2018-101836-B-100 (MCI/AEI/FEDER, EU), PID2019-110689RB-I00/AEI/10.13039/501100011033, and RTI2018-100920-J-I00. ExoMars is a space mission of the European Space Agency (ESA) and Roscosmos. 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 (BELLS), with the financial and contractual coordination by the ESAU Prod ex Office (PEA 4000103401, 4000121493) as well as by UK Space Agency through Grant ST/V002295/1, ST/V005332/1 and ST/S00145X/1 and Italian Space Agency through Grant 2018-2-HHS.0. US investigators were supported by the National Aeronautics and Space Administration. This work was supported by the Belgian Funds de la Recherche Scientific—FIRS under Grant 30442502 (ET_HOME). This project has received funding from the European Union Horizon 2020 research and innovation program under grant agreement No 101004052 (Road Map project)., With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2021-001131-S).

Published
2023

23. Attempting to use dust analogue from lab to study Martian atmosphere

Author

flimon, zachary, primary, erwin, justin, additional, vandaele, Ann Carine, additional, Neary, lori, additional, piccialli, arianna, additional, trompet, loic, additional, willame, yannick, additional, Vanhellemont, filip, additional, bauduin, sophie, additional, wolff, Michael, additional, Munoz, olga, additional, Martikainen, julia, additional, Gomez Martin, Juan Carlos, additional, and Moreno, Fernando, additional

Published
2022
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24. Observations and ongoing calibration of the infrared channels of NOMAD on ExoMars Trace Gas Orbiter

Author

Thomas, Ian, primary, Trompet, Loic, additional, Erwin, Justin, additional, Aoki, Shohei, additional, Vandaele, Ann Carine, additional, Daerden, Frank, additional, Ristic, Bojan, additional, Willame, Yannick, additional, Robert, Severine, additional, Piccialli, Arianna, additional, Flimon, Zachary, additional, Neary, Lori, additional, Viscardy, Sebastien, additional, Patel, Manish, additional, Bellucci, Giancarlo, additional, and Lopez-Moreno, Jose Juan, additional

Published
2022
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25. Preliminary results of nadir retrievals from NOMAD/UVIS using new dust properties from lab measurements

Author

Willame, Yannick, primary, Vandaele, Ann Carinne, additional, Erwin, Justin, additional, Wolff, Micheal, additional, Piccialli, Arianna, additional, Neary, Lori, additional, Flimon, Zachary, additional, Vanhellemont, Filip, additional, Daerden, Frank, additional, Muñoz, Olga, additional, Martikainen, Julia, additional, Depiesse, Cédric, additional, Mason, Jon, additional, Thomas, Ian, additional, Ristic, Bojan, additional, Patel, Manish, additional, Bellucci, Giancarlo, additional, and Lopez Moreno, José Juan, additional

Published
2022
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26. Dust climatology from NOMAD UVIS channel

Author

flimon, zachary, primary, erwin, justin, additional, vandaele, Ann Carine, additional, Neary, lori, additional, piccialli, arianna, additional, trompet, loic, additional, willame, yannick, additional, bauduin, sophie, additional, daerden, frank, additional, thomas, ian, additional, ristic, bojan, additional, mason, jon, additional, depiesse, cedric, additional, patel, manish, additional, bellucci, giancarlo, additional, and lopez moreno, jose juan, additional

Published
2022
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27. CO distributions retrieved from TGO NOMAD SO using multiple orders

Author

Yoshida, Nao, primary, Aoki, Shohei, additional, Vandaele, Ann Carine, additional, Nakagawa, Hiromu, additional, Thomas, Ian, additional, Erwin, Justin, additional, Daerden, Frank, additional, Trompet, Loïc, additional, Murata, Isao, additional, Terada, Naoki, additional, Neary, Lori, additional, Lopez-Valverde, Miguel, additional, Modak, Ashimananda, additional, Villanueva, Geronimo, additional, Liuzzi, Giuliano, additional, Kasaba, Yasumasa, additional, Patel, Manish, additional, Ristic, Bojan, additional, Bellucci, Giancarlo, additional, and López-Moreno, Jusé Juan, additional

Published
2022
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28. Measurements of water and its D/H as released from both Martian polar caps

Author

Villanueva, Geronimo, primary, Liuzzi, Giuliano, additional, Aoki, Shohei, additional, Stone, Shane, additional, Brines, Adrian, additional, Thomas, Ian, additional, Lopez-Valverde, Miguel, additional, Trompet, Loic, additional, Erwin, Justin, additional, Daerden, Frank, additional, Ristic, Bojan, additional, Smith, Michael, additional, Mumma, Michael, additional, Faggi, Sara, additional, Kofman, Vincent, additional, Robert, Severine, additional, Neary, Lori, additional, Patel, Manish, additional, Bellucci, Giancarlo, additional, and Vandaele, Ann-Carine, additional

Published
2022
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29. Mesospheric and thermospheric carbon dioxide and temperature profiles from NOMAD-SO onboard TGO.

Author

Trompet, Loïc, primary, Vandaele, Ann Carine, additional, Thomas, Ian, additional, Aoki, Shohei, additional, Daerden, Frank, additional, Erwin, Justin, additional, Flimon, Zachary, additional, Neary, Lori, additional, Mahieux, Arnaud, additional, Robert, Séverine, additional, Villanueva, Geronimo, additional, Liuzzi, Giuliano, additional, Lopez-Valverde, Miguel Angel, additional, Brines, Adrian, additional, Bellucci, Giancarlo, additional, Lopez-Moreno, José Juan, additional, and Patel, Manish, additional

Published
2022
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31. Two Martian years at Mars: Observations by NOMAD on ExoMars Trace Gas Orbiter

Author

Vandaele, Ann Carine, primary, Daerden, Frank, additional, Thomas, Ian R., additional, Depiesse, Cédric, additional, Erwin, Justin, additional, Flimon, Zachary, additional, Neary, Lori, additional, Piccialli, Arianna, additional, Ristic, Bojan, additional, Trompet, Loïc, additional, Viscardy, Sébastien, additional, Willame, Yannick, additional, Aoki, Shohei, additional, Gérard, Jean-Claude, additional, Villanueva, Geronimo, additional, Mason, Jon, additional, Patel, Manish, additional, Bellucci, Giancarlo, additional, Lopez-Valverde, Miguel, additional, and Lopez-Moreno, Jose Juan, additional

Published
2022
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32. Ozone in the Martian atmosphere observed by TGO/NOMAD-UVIS solar occultations

Author

Piccialli, Arianna, primary, Vandaele, Ann Carine, additional, Willame, Yannick, additional, Määttänen, Anni, additional, Trompet, Loïc, additional, Erwin, Justin, additional, Daerden, Frank, additional, Neary, Lori, additional, Aoki, Shohei, additional, Viscardy, Sébastien, additional, Thomas, Ian, additional, Depiesse, Cedric, additional, Ristic, Bojan, additional, Mason, Jon, additional, Patel, Manish, additional, Wolff, Michael, additional, Khayat, Alain, additional, Bellucci, Giancarlo, additional, and Lopez-Moreno, Jose Juan, additional

Published
2022
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33. Mars water vapor vertical distributions from the troposphere to the mesosphere from NOMAD Solar Occultation for Martian Years 34 and 35

Author

Brines, Adrian, primary, Lopez Valverde, Miguel Ángel, additional, Stolzenbach, Aurélien, additional, Modak, Ashim, additional, Funke, Bernd, additional, Gonzalez Galindo, Francisco, additional, Lopez Moreno, Jose Juan, additional, Aoki, Shohei, additional, Vandaele, Ann Carine, additional, Daerden, Frank, additional, Thomas, Ian, additional, Erwin, Justin, additional, Trompet, Loïc, additional, Ristic, Bojan, additional, Villanueva, Gerónimo Luis, additional, Liuzzi, Giuliano, additional, Patel, Manish, additional, and Bellucci, Giancarlo, additional

Published
2022
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35. Mapping of Martian CO from NOMAD solar occultation measurements for MY35 and 36

Author

Modak, Ashimananda, primary, Lopez-Valverde, Miguel-Angel, additional, Brines, Adrian, additional, Stolzenbach, Aurelien, additional, Funke, Bernd, additional, Gonzalez-Galindo, Francisco, additional, Lopez-Moreno, Jose-Juan, additional, Aoki, Shohe, additional, Villanueva, Geronimo, additional, Liuzzi, Giuliano, additional, Bellucci, Giancarlo, additional, Yoshida, Nao, additional, Erwin, Justin, additional, Trompet, Loic, additional, Thomas, Ian, additional, Daerden, Frank, additional, Ristic, Bojan, additional, Patel, Manish, additional, Vandaele, Ann Carine, additional, and Montmessin, Franck, additional

Published
2022
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38. The Deuterium Isotopic Ratio of Water Released From the Martian Caps as Measured With TGO/NOMAD

Author

Villanueva, Geronimo L., Liuzzi, Giuliano, Aoki, Shohei, Stone, Shane W., Brines, Adrian, Thomas, Ian R., Lopez‐Valverde, Miguel Angel, Trompet, Loic, Erwin, Justin, Daerden, Frank, Ristic, Bojan, Smith, Michael D., Mumma, Michael J., Faggi, Sara, Kofman, Vincent, Robert, Séverine, Neary, Lori, Patel, Manish, Bellucci, Giancarlo, Lopez‐Moreno, Jose Juan, Vandaele, Ann Carine, Ministerio de Ciencia e Innovación (España), European Commission, Belgian Science Policy Office, UK Space Agency, and Agenzia Spaziale Italiana

Subjects
History, Geophysics, Atmosphere, Mars, Water, General Earth and Planetary Sciences, Polar
Abstract

We report vertical profiles of water and D/H for one Martian year as measured with the TGO/NOMAD instrument. The observations were performed via solar occultation, providing water profiles up to ∼100 km and D/H up to ∼60 km, with a vertical resolution of 1–2 km. The measurements reveal dramatic variability of water and D/H over short timescales and with altitude and location on the planet. We investigated the release of seasonal water from the polar caps during southern and northern summer, by mapping water and its D/H near the polar regions. Above the hygropause, the D/H drops substantially below 2 VSMOW, and both seasonal polar caps show a consistent and enriched D/H of 5–7 VSMOW within the hygrosphere. © 2022 American Geophysical Union. All Rights Reserved., This work was supported by NASA’s Mars Program Office under WBS 604796, “Participation in the TGO/NOMAD Investigation of Trace Gases on Mars.” ExoMars is a space mission of the European Space Agency (ESA) and Roscosmos. 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 (The Open University). This project acknowledges funding by the Belgian Science Policy Office (BELSPO), with the financial and contractual coordination by the ESA Prodex Office (PEA 4000103401, 4000121493), by the Spanish MICINN through its Plan Nacional and by European funds under grants PGC2018-101836-B-I00 and ESP2017-87143-R (MINECO/FEDER) and by the Spanish Science Ministry Centro de Excelencia Severo Ochoa Program under grant SEV-2017-0709, as well as by the UK Space Agency through grants ST/V002295/1, ST/V005332/1, and ST/S00145X/1 and Italian Space Agency through grant 2018-2-HH.0. This work was supported by the Belgian Fonds de la Recherche Scientifique – FNRS (grant number 30442502, ET_HOME) and has received funding from the European Union’s Horizon 2020 research and innovation program (grant agreement no. 101004052, RoadMap project). SR thanks BELSPO for the FED-tWIN funding (Prf-2019-077 - RT-MOLEXO).

Published
2022

39. Variations in Vertical CO/CO2 Profiles in the Martian Mesosphere and Lower Thermosphere Measured by the ExoMars TGO/NOMAD: Implications of Variations in Eddy Diffusion Coefficient

Author

Yoshida, Nao, Nakagawa, Hiromu, Aoki, Shohei, Erwin, Justin, Vandaele, Ann Carine, Daerden, Frank, Thomas, Ian, Trompet, Loïc, Koyama, Shungo, Terada, Naoki, Neary, Lori, Murata, Isao, Villanueva, Geronimo, Liuzzi, Giuliano, Lopez‐Valverde, Miguel Angel, Brines, Adrian, Modak, Ashimananda, Kasaba, Yasumasa, Ristic, Bojan, Bellucci, Giancarlo, López‐Moreno, José Juan, Patel, Manish, Ministerio de Ciencia e Innovación (España), European Commission, Belgian Science Policy Office, UK Space Agency, and Agenzia Spaziale Italiana

Subjects
Geophysics, Retrieval, Atmospheric composition, General Earth and Planetary Sciences, Mars, Eddy diffusion coefficient, Spectroscopy, Mesosphere
Abstract

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited., Using the Nadir and Occultation for MArs Discovery instrument aboard Trace Gas Orbiter, we derived the CO/CO2 profiles between 75 and 105 km altitude with the equivalent width technique. The derived CO/CO2 profiles showed significant seasonal variations in the southern hemisphere with decreases near perihelion and increases near aphelion. The estimation of the CO/CO2 profiles with a one-dimensional photochemical model shows that an altitude-dependent eddy diffusion coefficient better reproduces the observed profiles than a vertically uniform one. Our estimation suggests that the eddy diffusion coefficient in Ls = 240–270 is uniformly larger by a factor of ∼2 than that in Ls = 90–120 in the southern hemisphere, while they are comparable in the northern hemisphere. This fact demonstrates that the eddy diffusion coefficient is variable with season and latitude. © 2022. The Authors., 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), 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/V002295/1, ST/V005332/1, and ST/S00145x/1 and Italian Space Agency through Grant 2018-2-HH.0. This work was supported by the Belgian Fonds de la Recherche Scientifique–FNRS under Grant No. 30442502 (ET_HOME). The IAA/CSIC team acknowledges financial support from the State Agency for Research of the Spanish MCIU through the “Center of Excellence Severo Ochoa” award for the Instituto de Astrofísica de Andalucía (SEV-2017-0709). US investigators were supported by the National Aeronautics and Space Administration. Canadian investigators were supported by the Canadian Space Agency. Y. N. is supported by The international Joint Graduate Program in Earth and Environmental Sciences, Tohoku University (GP-EES), and the Japanese Society for the Promotion of Science (JP21J13710). This work was supported by JSPS KAKENHI Grant Nos. 20H04605 and 19K03943.

Published
2022

41. The Deuterium Isotopic Ratio of Water Released From the Martian Caps as Measured With TGO/NOMAD

Author

Villanueva, Geronimo L., primary, Liuzzi, Giuliano, additional, Aoki, Shohei, additional, Stone, Shane W., additional, Brines, Adrian, additional, Thomas, Ian R., additional, Lopez‐Valverde, Miguel Angel, additional, Trompet, Loic, additional, Erwin, Justin, additional, Daerden, Frank, additional, Ristic, Bojan, additional, Smith, Michael D., additional, Mumma, Michael J., additional, Faggi, Sara, additional, Kofman, Vincent, additional, Robert, Séverine, additional, Neary, Lori, additional, Patel, Manish, additional, Bellucci, Giancarlo, additional, Lopez‐Moreno, Jose Juan, additional, and Vandaele, Ann Carine, additional

Published
2022
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42. Variations in Vertical CO/CO 2 Profiles in the Martian Mesosphere and Lower Thermosphere Measured by the ExoMars TGO/NOMAD: Implications of Variations in Eddy Diffusion Coefficient

Author

Yoshida, Nao, primary, Nakagawa, Hiromu, additional, Aoki, Shohei, additional, Erwin, Justin, additional, Vandaele, Ann Carine, additional, Daerden, Frank, additional, Thomas, Ian, additional, Trompet, Loïc, additional, Koyama, Shungo, additional, Terada, Naoki, additional, Neary, Lori, additional, Murata, Isao, additional, Villanueva, Geronimo, additional, Liuzzi, Giuliano, additional, Lopez‐Valverde, Miguel Angel, additional, Brines, Adrian, additional, Modak, Ashimananda, additional, Kasaba, Yasumasa, additional, Ristic, Bojan, additional, Bellucci, Giancarlo, additional, López‐Moreno, José Juan, additional, and Patel, Manish, additional

Published
2022
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45. The Deuterium Isotopic Ratio of Water Released From the Martian Caps as Measured With TGO/NOMAD

Author

Ministerio de Ciencia e Innovación (España), European Commission, Belgian Science Policy Office, UK Space Agency, Agenzia Spaziale Italiana, Villanueva, Geronimo L., Liuzzi, Giuliano, Aoki, Shohei, Stone, Shane W., Brines, Adrian, Thomas, Ian R., López-Valverde, M. A., Trompet, Loic, Erwin, Justin T., Daerden, Frank, Ristic, Bojan, Smith, Michael D., Mumma, Michael J., Faggi, Sara, Kofman, Vincent, Robert, Séverine, Neary, Lori, Patel, Manish R., Bellucci, Giancarlo, López-Moreno, José Juan, Vandaele, Ann Carine, Ministerio de Ciencia e Innovación (España), European Commission, Belgian Science Policy Office, UK Space Agency, Agenzia Spaziale Italiana, Villanueva, Geronimo L., Liuzzi, Giuliano, Aoki, Shohei, Stone, Shane W., Brines, Adrian, Thomas, Ian R., López-Valverde, M. A., Trompet, Loic, Erwin, Justin T., Daerden, Frank, Ristic, Bojan, Smith, Michael D., Mumma, Michael J., Faggi, Sara, Kofman, Vincent, Robert, Séverine, Neary, Lori, Patel, Manish R., Bellucci, Giancarlo, López-Moreno, José Juan, and Vandaele, Ann Carine

Abstract

We report vertical profiles of water and D/H for one Martian year as measured with the TGO/NOMAD instrument. The observations were performed via solar occultation, providing water profiles up to ∼100 km and D/H up to ∼60 km, with a vertical resolution of 1–2 km. The measurements reveal dramatic variability of water and D/H over short timescales and with altitude and location on the planet. We investigated the release of seasonal water from the polar caps during southern and northern summer, by mapping water and its D/H near the polar regions. Above the hygropause, the D/H drops substantially below 2 VSMOW, and both seasonal polar caps show a consistent and enriched D/H of 5–7 VSMOW within the hygrosphere. © 2022 American Geophysical Union. All Rights Reserved.

Published
2022

46. Variations in Vertical CO/CO2 Profiles in the Martian Mesosphere and Lower Thermosphere Measured by the ExoMars TGO/NOMAD: Implications of Variations in Eddy Diffusion Coefficient

Author

Ministerio de Ciencia e Innovación (España), European Commission, Belgian Science Policy Office, UK Space Agency, Agenzia Spaziale Italiana, Yoshida, Nao, Nakagawa, Hiromu, Aoki, Shohei, Erwin, Justin T., Vandaele, Ann Carine, Daerden, Frank, Thomas, Ian R., Trompet, Loïc., Koyama, Shungo, Terada, Naoki, Neary, Lori, Murata, Isao, Villanueva, Geronimo L., Liuzzi, Giuliano, López-Valverde, M. A., Brines, Adrian, Modak, Ashimananda, Kasaba, Yasumasa, Ristic, Bojan, Bellucci, Giancarlo, López-Moreno, José Juan, Patel, Manish R., Ministerio de Ciencia e Innovación (España), European Commission, Belgian Science Policy Office, UK Space Agency, Agenzia Spaziale Italiana, Yoshida, Nao, Nakagawa, Hiromu, Aoki, Shohei, Erwin, Justin T., Vandaele, Ann Carine, Daerden, Frank, Thomas, Ian R., Trompet, Loïc., Koyama, Shungo, Terada, Naoki, Neary, Lori, Murata, Isao, Villanueva, Geronimo L., Liuzzi, Giuliano, López-Valverde, M. A., Brines, Adrian, Modak, Ashimananda, Kasaba, Yasumasa, Ristic, Bojan, Bellucci, Giancarlo, López-Moreno, José Juan, and Patel, Manish R.

Abstract

Using the Nadir and Occultation for MArs Discovery instrument aboard Trace Gas Orbiter, we derived the CO/CO2 profiles between 75 and 105 km altitude with the equivalent width technique. The derived CO/CO2 profiles showed significant seasonal variations in the southern hemisphere with decreases near perihelion and increases near aphelion. The estimation of the CO/CO2 profiles with a one-dimensional photochemical model shows that an altitude-dependent eddy diffusion coefficient better reproduces the observed profiles than a vertically uniform one. Our estimation suggests that the eddy diffusion coefficient in Ls = 240–270 is uniformly larger by a factor of ∼2 than that in Ls = 90–120 in the southern hemisphere, while they are comparable in the northern hemisphere. This fact demonstrates that the eddy diffusion coefficient is variable with season and latitude. © 2022. The Authors.

Published
2022

47. Planet-Wide Ozone Destruction in the Middle Atmosphere on Mars During Global Dust Storm

Author

Ministerio de Ciencia e Innovación (España), European Commission, Belgian Science Policy Office, UK Space Agency, Daerden, Frank, Neary, L., Wolff, M. J., Clancy, R. T., Lefèvre, F., Whiteway, J. A., Viscardy, S., Piccialli, A., Willame, Y., Depiesse, C., Aoki, Shohei, Thomas, Ian R., Ristic, Bojan, Erwin, Justin T., Gérard, J. -C., Sandor, B. J., Khayat, A., Smith, M. D., Mason, Jonathon P., Patel, Manish R., Villanueva, Geronimo L., Liuzzi, Giuliano, Bellucci, Giancarlo, López-Moreno, José Juan, Vandaele, Ann Carine, Ministerio de Ciencia e Innovación (España), European Commission, Belgian Science Policy Office, UK Space Agency, Daerden, Frank, Neary, L., Wolff, M. J., Clancy, R. T., Lefèvre, F., Whiteway, J. A., Viscardy, S., Piccialli, A., Willame, Y., Depiesse, C., Aoki, Shohei, Thomas, Ian R., Ristic, Bojan, Erwin, Justin T., Gérard, J. -C., Sandor, B. J., Khayat, A., Smith, M. D., Mason, Jonathon P., Patel, Manish R., Villanueva, Geronimo L., Liuzzi, Giuliano, Bellucci, Giancarlo, López-Moreno, José Juan, and Vandaele, Ann Carine

Abstract

The Nadir and Occultation for MArs Discovery (NOMAD)/UV-visible (UVIS) spectrometer on the ExoMars Trace Gas Orbiter provided observations of ozone (O3) and water vapor in the global dust storm of 2018. Here we show in detail, using advanced data filtering and chemical modeling, how Martian O3 in the middle atmosphere was destroyed during the dust storm. In data taken exactly 1 year later when no dust storm occurred, the normal situation had been reestablished. The model simulates how water vapor is transported to high altitudes and latitudes in the storm, where it photolyzes to form odd hydrogen species that catalyze O3. O3 destruction is simulated at all latitudes and up to 100 km, except near the surface where it increases. The simulations also predict a strong increase in the photochemical production of atomic hydrogen in the middle atmosphere, consistent with the enhanced hydrogen escape observed in the upper atmosphere during global dust storms. © 2022 The Authors.

Published
2022

48. Martian Atmospheric Temperature and Density Profiles During the First Year of NOMAD/TGO Solar Occultation Measurements.

Author

López‐Valverde, Miguel Angel, Funke, Bernd, Brines, Adrian, Stolzenbach, Aurèlien, Modak, Ashimananda, Hill, Brittany, González‐Galindo, Francisco, Thomas, Ian, Trompet, Loic, Aoki, Shohei, Villanueva, Gerónimo, Liuzzi, Giuliano, Erwin, Justin, Grabowski, Udo, Forget, Francois, López‐Moreno, José Juan, Rodriguez‐Gómez, Julio, Ristic, Bojan, Daerden, Frank, and Bellucci, Giancarlo

Subjects
ATMOSPHERIC temperature, ATMOSPHERIC density, CLIMATE change models, FRONTS (Meteorology), DUST storms, GLOBAL warming
Abstract

We present vertical profiles of temperature and density from solar occultation (SO) observations by the "Nadir and Occultation for Mars Discovery" (NOMAD) spectrometer on board the Trace Gas Orbiter during its first operational year, which covered the second half of Mars Year 34. We used calibrated transmittance spectra in 380 scans, and apply an in‐house pre‐processing to clean data systematics. Temperature and CO2 profiles up to about 90 km, with consistent hydrostatic adjustment, are obtained, after adapting an Earth‐tested retrieval scheme to Mars conditions. Both pre‐processing and retrieval are discussed to illustrate their performance and robustness. Our results reveal the large impact of the MY34 Global Dust Storm (GDS), which warmed the atmosphere at all altitudes. The large GDS aerosols opacity limited the sounding of tropospheric layers. The retrieved temperatures agree well with global climate models (GCM) at tropospheric altitudes, but NOMAD mesospheric temperatures are wavier and globally colder by 10 K in the perihelion season, particularly during the GDS and its decay phase. We observe a warm layer around 80 km during the Southern Spring, especially in the Northern Hemisphere morning terminator, associated to large thermal tides, significantly stronger than in the GCM. Cold mesospheric pockets, close to CO2 condensation temperatures, are more frequently observed than in the GCM. NOMAD CO2 densities show oscillations upon a seasonal trend that track well the latitudinal variations expected. Results uncertainties and suggestions to improve future data re‐analysis are briefly discussed. Plain Language Summary: The detailed variation of temperature and density with altitude is of paramount importance to characterize the atmospheric state and to constrain the chemistry and dynamics as a whole. The Nadir and Occultation for Mars Discovery (NOMAD) instrument on board the Trace Gas Orbiter (TGO) has among its key targets the characterization of the thermal state with unprecedented vertical resolution. This is the target of this work, where we analyzed transmittance spectra obtained from the NOMAD solar occultation channel, with a state‐of‐the‐art retrieval scheme, adapted from Earth to Mars conditions and geometry. We applied it to the first year of TGO observations, which covered the last two Mars seasons of Mars Year 34. The results permit to study the temperature structure up to 90 km and its seasonal and latitudinal variations, revealing the impact of the MY34 Global Dust Storm, a warm layer at mesospheric altitudes not present in climate models, more frequent cold pockets than in current global climate models, and generally, colder temperature at those altitudes, all of which can be of importance for the validation of these climate models. Key Points: Temperature and density profiles up to 90 km are retrieved from Nadir and Occultation for Mars Discovery (NOMAD) first year of solar occultations, covering two seasons of Mars Year 34NOMAD temperatures agree well with climate model predictions below 50 km but are wavier and globally colder by about 10 K at high altitudesWe report large thermal tides producing warm layers at 80 km in the morning terminator. Also strong warming by the 2018 global dust storm [ABSTRACT FROM AUTHOR]

Published
2023
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49. Publisher Correction: No detection of methane on Mars from early ExoMars Trace Gas Orbiter observations

Author

Korablev, Oleg, Vandaele, Ann Carine, Montmessin, Franck, Fedorova, Anna A., Trokhimovskiy, Alexander, Forget, François, Lefèvre, Franck, Daerden, Frank, Thomas, Ian R., Trompet, Loïc, Erwin, Justin T., Aoki, Shohei, Robert, Séverine, Neary, Lori, Viscardy, Sébastien, Grigoriev, Alexey V., Ignatiev, Nikolay I., Shakun, Alexey, Patrakeev, Andrey, Belyaev, Denis A., Bertaux, Jean-Loup, Olsen, Kevin S., Baggio, Lucio, Alday, Juan, Ivanov, Yuriy S., Ristic, Bojan, Mason, Jon, Willame, Yannick, Depiesse, Cédric, Hetey, Laszlo, Berkenbosch, Sophie, Clairquin, Roland, Queirolo, Claudio, Beeckman, Bram, Neefs, Eddy, Patel, Manish R., Bellucci, Giancarlo, López-Moreno, Jose-Juan, Wilson, Colin F., Etiope, Giuseppe, Zelenyi, Lev, Svedhem, Håkan, Vago, Jorge L., and The ACS and NOMAD Science Teams

Published
2019
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50. Publisher Correction: Martian dust storm impact on atmospheric H2O and D/H observed by ExoMars Trace Gas Orbiter

Author

Vandaele, Ann Carine, Korablev, Oleg, Daerden, Frank, Aoki, Shohei, Thomas, Ian R., Altieri, Francesca, López-Valverde, Miguel, Villanueva, Geronimo, Liuzzi, Giuliano, Smith, Michael D., Erwin, Justin T., Trompet, Loïc, Fedorova, Anna A., Montmessin, Franck, Trokhimovskiy, Alexander, Belyaev, Denis A., Ignatiev, Nikolay I., Luginin, Mikhail, Olsen, Kevin S., Baggio, Lucio, Alday, Juan, Bertaux, Jean-Loup, Betsis, Daria, Bolsée, David, Clancy, R. Todd, Cloutis, Edward, Depiesse, Cédric, Funke, Bernd, Garcia-Comas, Maia, Gérard, Jean-Claude, Giuranna, Marco, Gonzalez-Galindo, Francisco, Grigoriev, Alexey V., Ivanov, Yuriy S., Kaminski, Jacek, Karatekin, Ozgur, Lefèvre, Franck, Lewis, Stephen, López-Puertas, Manuel, Mahieux, Arnaud, Maslov, Igor, Mason, Jon, Mumma, Michael J., Neary, Lori, Neefs, Eddy, Patrakeev, Andrey, Patsaev, Dmitry, Ristic, Bojan, Robert, Séverine, Schmidt, Frédéric, Shakun, Alexey, Teanby, Nicholas A., Viscardy, Sébastien, Willame, Yannick, Whiteway, James, Wilquet, Valérie, Wolff, Michael J., Bellucci, Giancarlo, Patel, Manish R., López-Moreno, Jose-Juan, Forget, François, Wilson, Colin F., Young, Roland, Svedhem, Håkan, Vago, Jorge L., Rodionov, Daniel, NOMAD Science Team, and ACS Science Team

Published
2019
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