12 results on '"Vandaele, Ann Carine"'
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2. 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
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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
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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.
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- 2022
3. Composition and Chemistry of the Neutral Atmosphere of Venus
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Marcq, Emmanuel, Mills, Franklin P., Parkinson, Christopher D., and Vandaele, Ann Carine
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- 2017
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4. 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.
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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, and Bellucci, Giancarlo
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DIFFUSION coefficients ,MESOSPHERE ,TRACE gases ,THERMOSPHERE ,MIDDLE atmosphere ,EDDIES - 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. Plain Language Summary: The eddy diffusion coefficient is widely used to parameterize the efficiency of vertical diffusion in the planetary atmosphere, whose variation characterizes the transportation of trace gas species. Additionally, it could vary their vertical distributions in the middle and upper atmosphere, which might cause an impact on the species escaping to space. However, the variability of the eddy diffusion coefficient in those altitude regions have been poorly understood. In this study, we focus on the estimation of variation in the eddy diffusion coefficient by analyzing the CO and CO2 measurements made by the ExoMars Trace Gas Orbiter. The observed CO/CO2 ratio between altitudes of 75 and 105 km shows a significant seasonal variation in the southern hemisphere. The observed CO/CO2 profiles are compared with the simulated profiles obtained with a one‐dimensional photochemical model assigning several shapes and intensity of eddy diffusion coefficient. The comparison shows that the eddy diffusion coefficient is not constant but variable depending on altitude, season, and latitude, which suggests that the efficiency of the vertical diffusion varies with season and latitude. This fact is useful to other 1D photochemical models to reproduce the seasonal and latitudinal variation of atmospheric composition. Key Points: The CO/CO2 profiles from 75 to 105 km measured by NOMAD aboard TGO are used to investigate variations in the eddy diffusion coefficientThe estimated CO/CO2 profiles agree well with the observed profiles if altitude‐dependent eddy diffusion coefficients are consideredOur results demonstrate a substantial seasonal variation in the eddy diffusion coefficient in the southern hemisphere [ABSTRACT FROM AUTHOR]
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- 2022
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5. NOMAD, an Integrated Suite of Three Spectrometers for the ExoMars Trace Gas Mission: Technical Description, Science Objectives and Expected Performance
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Vandaele, Ann Carine, López-Moreno, José Juan, Patel, Manish R., Bellucci, Giancarlo, Daerden, Frank, Ristic, Bojan, Robert, S., Thomas, Ian R., Wilquet, V., Allen, M., Alonso-Rodrigo, G., Altieri, F., Aoki, Shohei, Bolsée, D., Clancy, T., Cloutis, E., Depiesse, C., Drummond, R., Fedorova, A., Formisano, V., Funke, Bernd, González-Galindo, F., Geminale, A., Gérard, Jean-Claude, Giuranna, M., Hetey, L., Ignatiev, N., Kaminski, J., Karatekin, O., Kasaba, Y., Leese, M., Lefèvre, F., Lewis, S. R., López-Puertas, Manuel, López-Valverde, M. A., Mahieux, A., Mason, J., McConnell, J., Mumma, M., Neary, L., Neefs, E., Renotte, E., Rodriguez-Gomez, J., Sindoni, G., Smith, M., Stiepen, A., Trokhimovsky, A., Vander Auwera, J., Villanueva, Geronimo L., Viscardy, S., Whiteway, J., Willame, Y., Wolff, Michael T., Patel, M., D’aversa, E., Fussen, D., García Comas, Maia, Hewson, W., McConnel, J., Novak, R., Oliva, F., Piccialli, A., Aparicio del Moral, Beatriz, Barzin, P., BenMoussa, A., Berkenbosch, S., Biondi, D., Bonnewijn, S., Candini, G. P., Clairquin, R., Cubas, J., De-Lanoye, S., Giordanengo, B., Gissot, S., Gomez, A., Maes, J., Mazy, E., Mazzoli, A., Meseguer, J., Morales, Rafael, Orban, A., Pastor, Carmen, Perez-Grande, I., Queirolo, C., Saggin, B., Samain, V., Sanz Andres, A., Sanz Mesa, Rosario, Simar, J.-F., Thibert, T., Jerónimo, José María, The NOMAD Team, Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique (BIRA-IASB), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), School of Physical Sciences [Milton Keynes], Faculty of Science, Technology, Engineering and Mathematics [Milton Keynes], The Open University [Milton Keynes] (OU)-The Open University [Milton Keynes] (OU), Space Science and Technology Department [Didcot] (RAL Space), STFC Rutherford Appleton Laboratory (RAL), Science and Technology Facilities Council (STFC)-Science and Technology Facilities Council (STFC), Istituto di Astrofisica e Planetologia Spaziali - INAF (IAPS), Istituto Nazionale di Astrofisica (INAF), Jet Propulsion Laboratory (JPL), California Institute of Technology (CALTECH)-NASA, Instituto Universitario de Microgravedad 'Ignacio Da Riva' (IDR), Universidad Politécnica de Madrid (UPM), Space Science Institute [Boulder] (SSI), Department of Geography [Winnipeg], University of Winnipeg, Space Research Institute of the Russian Academy of Sciences (IKI), Russian Academy of Sciences [Moscow] (RAS), Laboratoire de Physique Atmosphérique et Planétaire (LPAP), Université de Liège, Institute of Geophysics [Warsaw], Polska Akademia Nauk = Polish Academy of Sciences (PAN), Royal Observatory of Belgium [Brussels] (ROB), Tohoku University [Sendai], PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Fonds National de la Recherche Scientifique [Bruxelles] (FNRS), York University [Toronto], NASA Goddard Space Flight Center (GSFC), Centre Spatial de Liège (CSL), Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Service de Chimie Quantique et Photophysique, Université libre de Bruxelles (ULB), Catholic University of America, Belgian Science Policy Office, European Space Agency, Ministerio de Ciencia e Innovación (España), European Commission, UK Space Agency, Agenzia Spaziale Italiana, and Fonds de la Recherche Scientifique (Fédération Wallonie-Bruxelles)
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010504 meteorology & atmospheric sciences ,Solar occultation ,education ,Physique atomique et moléculaire ,Exploration of Mars ,01 natural sciences ,Occultation ,law.invention ,Orbiter ,Mars atmosphere ,law ,0103 physical sciences ,Nadir ,Chimie ,natural sciences ,010303 astronomy & astrophysics ,Spectroscopy ,0105 earth and related environmental sciences ,Remote sensing ,Ultraviolet ,Martian ,Astronomy and Astrophysics ,Dust ,Atmosphere of Mars ,Mars Exploration Program ,Nadir observations ,ExoMars ,Trace gas ,[SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM] ,Spectroscopie [électromagnétisme, optique, acoustique] ,13. Climate action ,Space and Planetary Science ,Visible ,Environmental science ,Infrared ,Methane ,Composition - Abstract
Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), The NOMAD (“Nadir and Occultation for MArs Discovery”) spectrometer suite on board the ExoMars Trace Gas Orbiter (TGO) has been designed to investigate the composition of Mars’ atmosphere, with a particular focus on trace gases, clouds and dust. The detection sensitivity for trace gases is considerably improved compared to previous Mars missions, compliant with the science objectives of the TGO mission. This will allow for a major leap in our knowledge and understanding of the Martian atmospheric composition and the related physical and chemical processes. The instrument is a combination of three spectrometers, covering a spectral range from the UV to the mid-IR, and can perform solar occultation, nadir and limb observations. In this paper, we present the science objectives of the instrument and explain the technical principles of the three spectrometers. We also discuss the expected performance of the instrument in terms of spatial and temporal coverage and detection sensitivity.© 2018, The Author(s)., 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 MICINN through its Plan Nacional and by European funds under grant ESP2015-65064-C2-1-P (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. The research was performed as part of the >Excellence of Science> project >Evolution and Tracers of Habitability on Mars and the Earth> (30442502). SA acknowledge support from the FNRS, Be.
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- 2018
6. Science objectives and performances of NOMAD, a spectrometer suite for the ExoMars TGO mission
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Vandaele, A. C, Neefs, E., Drummond, R., Thomas, I. R., Daerden, F., Lopez Moreno, J. J., Rodriguez, J., Patel, M. R., Bellucci, G., Allen, M., Altieri, F., Bolsée, D., Clancy, T., Delanoye, S., Depiesse, C., Cloutis, E., Fedorova, A., Formisano, V., Funke, B., Fussen, D., Geminale, A., Gérard, J. C., Giuranna, M., Ignatiev, N., Kaminski, J., Karatekin, O., Lefèvre, F., López Puertas, M., López Valverde, M., Mahieux, A., Mcconnell, J., Mumma, M., Neary, L., Renotte, E., Ristic, B., Robert, S., Smith, M., Trokhimovsky, S., Vanderauwera, J., Villanueva, G., Whiteway, J., Wilquet, V., Wolff, M., Vandaele, Ann Carine, Lopez Moreno, Jose Juan, Bellucci, Giancarlo, Patel, Manish, Allen, Mark, Altieri, Francesca, Aoki, Shohei, Bolsée, David, Clancy, Todd, Cloutis, Edward, Daerden, Frank, Depiesse, Cédric, Fedorova, Anna, Formisano, Vittorio, Funke, Bernd, Fussen, Didier, Garcia Comas, Maya, Geminale, Anna, Gérard, Jean Claude, Gillotay, Didier, Giuranna, Marco, Gonzalez Galindo, Francisco, Ignatiev, Nicolai, Kaminski, Jacek, Karatekin, Ozgur, Kasabe, Yasumasa, Lefèvre, Franck, Lewis, Stephen, López Puertas, Manuel, López Valverde, Miguel, Mahieux, Arnaud, Mason, Jon, Mumma, Mike, Neary, Lori, Neefs, Eddy, Renotte, Etienne, Robert, Séverine, Sindoni, Giuseppe, Smith, Mike, Thomas, Ian R., Trokhimovsky, Sacha, Vander Auwera, Jean, Villanueva, Geronimo, Whiteway, Jim, Willame, Yannick, Wilquet, Valerie, Wolff, Mike, Alonso Rodrigo, Gustavo, Aparicio Del Moral, Beatriz, Barzin, Pascal, Ben Moussa, Ali, Berkenbosch, Sophie, Biondi, David, Bonnewijn, Sabrina, Candini, Gian Paolo, Clairquin, Roland, Cubas, Javier, Delanoye, Sofie, Giordanengo, Boris, Gissot, Samuel, Gomez, Alejandro, Zafra, Jose Jeronimo, Leese, Mark, Maes, Jeroen, Mazy, Emmanuel, Mazzoli, Alexandra, Meseguer, Jose, Morales, Rafael, Orban, Anne, Pastor Morales, Maria Del Carmen, Perez Grande, Isabel, Ristic, Bojan, Rodriguez Gomez, Julio, Saggin, Bortolino, Samain, Valérie, Sanz Andres, Angel, Sanz, Rosario, Simar, Juan Felipe, Thibert, Tanguy, Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique (BIRA-IASB), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), The Open University [Milton Keynes] (OU), Istituto di Astrofisica e Planetologia Spaziali - INAF (IAPS), Istituto Nazionale di Astrofisica (INAF), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Space Science Institute [Boulder] (SSI), Department of Geography [Winnipeg], University of Winnipeg, Space Research Institute of the Russian Academy of Sciences (IKI), Russian Academy of Sciences [Moscow] (RAS), Laboratoire de Physique Atmosphérique et Planétaire (LPAP), Université de Liège, York University [Toronto], Royal Observatory of Belgium [Brussels] (ROB), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), NASA Goddard Space Flight Center (GSFC), Centre Spatial de Liège (CSL), Spectroscopie de l'atmosphère, Service de Chimie Quantique et Photophysique, Université libre de Bruxelles (ULB), and Catholic University of America
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[SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP] ,Solar ,Occultation ,law.invention ,Orbiter ,Mars atmosphere ,law ,Nadir ,Aerosol ,Observations ,Spectroscopy ,Ultraviolet ,Remote sensing ,Spectrometer ,[SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR] ,Suite ,Astronomy and Astrophysics ,Mars Exploration Program ,Atmosphere of Mars ,ExoMars ,Trace gas ,[SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM] ,Space and Planetary Science ,Visible ,Composition ,Infrared ,Methane ,Occultation Nadir ,Environmental science - Abstract
International audience; The NOMAD spectrometer suite on the ExoMars Trace Gas Orbiter will map the composition and distribution of Mars' atmospheric trace species in unprecedented detail, fulfilling many of the scientific objectives of the joint ESA-Roscosmos ExoMars Trace Gas Orbiter mission. The instrument is a combination of three channels, covering a spectral range from the UV to the IR, and can perform solar occultation, nadir and limb observations. In this paper, we present the science objectives of the instrument and how these objectives have influenced the design of the channels. We also discuss the expected performance of the instrument in terms of coverage and detection sensitivity.
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- 2015
7. Composition and Chemistry of the Neutral Atmosphere of Venus.
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Marcq, Emmanuel, Mills, Franklin P., Parkinson, Christopher D., and Vandaele, Ann Carine
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This paper deals with the composition and chemical processes occurring in the neutral atmosphere of Venus. Since the last synthesis, observers as well as modellers have emphasised the spatial and temporal variability of minor species, going beyond a static and uniform picture that may have prevailed in the past. The outline of this paper acknowledges this situation and follows closely the different dimensions along which variability in composition can be observed: vertical, latitudinal, longitudinal, temporal. The strong differences between the atmosphere below and above the cloud layers also dictate the structure of this paper. Observational constraints, obtained from both Earth and Venus Express, as well as 1D, 2D and 3D models results obtained since 1997 are also extensively referred and commented by the authors. An non-exhaustive list of topics included follows: modelled and observed latitudinal and vertical profiles of CO and OCS below the clouds of Venus; vertical profiles of CO and SO
2 above the clouds as observed by solar occultation and modelled; temporal and spatial variability of sulphur oxides above the clouds. As a conclusion, open questions and topics of interest for further studies are discussed. [ABSTRACT FROM AUTHOR]- Published
- 2018
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8. First observation of 628 CO2 isotopologue band at 3.3 μm in the atmosphere of Venus by solar occultation from Venus Express
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Bertaux, Jean-Loup, Vandaele, Ann Carine, Wilquet, Valérie, Montmessin, F., Dahoo, R., Villard, E., Korablev, O., and Fedorova, A.
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ATMOSPHERE , *SPHERICAL astronomy , *INNER planets , *ASTRONOMY - Abstract
Abstract: The new ESA Venus Express orbiter is the first mission applying the probing technique of solar and stellar occultation to the atmosphere of Venus, with the SPICAV/SOIR instrument. SOIR is a new type of spectrometer used for solar occultations in the range 2.2–4.3 μm. Thanks to a high spectral resolving power (unprecedented in planetary space exploration), a new gaseous absorption band was soon detected in the atmospheric transmission spectra around 2982 cm−1, showing a structure resembling an unresolved Q branch and a number of isolated lines with a regular wave number pattern. This absorption could not be matched to any species contained in HITRAN or GEISA databases, but was found very similar to an absorption pattern observed by a US team in the spectrum of solar light reflected by the ground of Mars [Villanueva, G.L., Mumma, M.J., Novak, R.E., Hewagama, T., 2008. Icarus 195 (1), 34–44]. This team then suggested to us that the absorption was due to an uncatalogued transition of the 16O12C18O molecule. The possible existence of this band was soon confirmed from theoretical considerations by Perevalov and Tashkun. Some SOIR observations of the atmospheric transmission are presented around 2982 cm−1, and rough calculations of line strengths of the Q branch are produced, based on the isotopic ratio measured earlier in the lower atmosphere of Venus. This discovery emphasizes the role of isotopologues of CO2 (as well as H2O and HDO) as important greenhouse gases in the atmosphere of Venus. [Copyright &y& Elsevier]
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- 2008
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9. UV/Vis+ photochemistry database: Structure, content and applications.
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Noelle, Andreas, Vandaele, Ann Carine, Martin-Torres, Javier, Yuan, Chenyi, Rajasekhar, Balabhadrapatruni N., Fahr, Askar, Hartmann, Gerd K., Lary, David, Lee, Yuan-Pern, Limão-Vieira, Paulo, Locht, Robert, McNeill, Kristopher, Orlando, John J., Salama, Farid, and Wayne, Richard P.
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PHOTOCHEMISTRY , *ENVIRONMENTAL chemistry , *PLASMA physics , *LINEAR dichroism , *EARTH sciences - Abstract
• The "science-softCon UV/Vis+ photochemistry database" contains EUV-VUV-UV–Vis-NIR spectral data. • The database also contains quantum yields and photolysis related data. • The database provides valuable information for astrophysics, earth and planetary sciences, medical and pharmaceutical sciences. The "science-softCon UV/Vis+ Photochemistry Database" (www.photochemistry.org) is a large and comprehensive collection of EUV-VUV-UV–Vis-NIR spectral data and other photochemical information assembled from published peer-reviewed papers. The database contains photochemical data including absorption, fluorescence, photoelectron, and circular and linear dichroism spectra, as well as quantum yields and photolysis related data that are critically needed in many scientific disciplines. This manuscript gives an outline regarding the structure and content of the "science-softCon UV/Vis+ Photochemistry Database". The accurate and reliable molecular level information provided in this database is fundamental in nature and helps in proceeding further to understand photon, electron and ion induced chemistry of molecules of interest not only in spectroscopy, astrochemistry, astrophysics, Earth and planetary sciences, environmental chemistry, plasma physics, combustion chemistry but also in applied fields such as medical diagnostics, pharmaceutical sciences, biochemistry, agriculture, and catalysis. In order to illustrate this, we illustrate the use of the UV/Vis+ Photochemistry Database in four different fields of scientific endeavor. [ABSTRACT FROM AUTHOR]
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- 2020
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10. Machine learning for automatic identification of new minor species.
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Schmidt, Frédéric, Mermy, Guillaume Cruz, Erwin, Justin, Robert, Séverine, Neary, Lori, Thomas, Ian R., Daerden, Frank, Ristic, Bojan, Patel, Manish R., Bellucci, Giancarlo, Lopez-Moreno, Jose-Juan, and Vandaele, Ann-Carine
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MACHINE learning , *AUTOMATIC identification , *CARBON dioxide , *NONNEGATIVE matrices , *ONLINE databases - Abstract
• Fully blind machine learning approach to produce a quicklook and discover new lines on large spectroscopic datasets. • Validation on ESA/ExoMars TGO NOMAD-SO dataset. • Absence of methane in 100–500 ppt from this analysis. • Exhibition of unexpected lines. 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 ~ 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 ~ 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. The methodology is the following: we proposed a way to 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 104, 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. Image, graphical abstract [ABSTRACT FROM AUTHOR]
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- 2021
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11. Inversion des spectres infrarouges enregistrés par l'instrument SOIR à bord de la sonde Venus Express/Inversion of the infrared spectra recorded by the SOIR instrument on board Venus Express
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Mahieux, Arnaud, Biémont, Emile, Vander Auwera, Jean, Gérard, Jean-Claude, Godefroid, Michel, Vandaele, Ann Carine, Degrez, Gérard, Bertaux, Jean-Loup, and Herman, Michel
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Vénus ,Calibration ,Spectroscopie ,Terminateur / Venus ,Terminator ,Spectroscopy - Abstract
Vénus, deuxième planète du système solaire, souvent appelée sœur de la Terre, car présentant des caractéristiques de taille et de masse similaires, est fort différente de notre planète. En effet, son atmosphère est beaucoup plus dense et dynamiquement active que celle de la Terre. Dans ce travail, nous nous concentrerons sur la région s'étendant de 70 km à 180~km d'altitude :la mésosphère et la basse thermosphère. SOIR, acronyme de Solar Occultation in the InfraRed, est un instrument russo-franco-belge embarqué à bord de la mission Venus Express de l'Agence Spatiale Européenne. Il utilise un réseau à échelle comme élément diffractant. La plage de nombre d'onde mesurable par SOIR s'étend de 2200 cm-1 à 4400 cm-1, ou 4.3 µm à 2.2 µm en longueur d'onde. Les ordres de diffraction utiles varient de 101 à 194. Un filtre acousto-optique - AOTF - est utilisé comme passe-bande pour sélectionner les ordres de diffraction. La résolution de l'instrument varie de 0.13 à 0.24 cm-1. Du fait d'un temps de développement raccourci, presque toutes les calibrations de l'instrument ont dû être réalisées en vol. Elles comprennent les calibrations relatives au réseau à échelle (angle exact de Blaze et fonction de Blaze), au détecteur (non-uniformité pixel à pixel, courbe de sensibilité spectrale, relation entre les pixels et les nombres d'onde, résolution de l'instrument, intervalle d'échantillonnage spectral, rapport signal sur bruit, background thermique) et à l'AOTF (relation entre la radio-fréquence d'excitation de l'AOTF et les nombres d'onde, fonction de transfert de l'AOTF). L'approche et la réalisation de ces différentes calibrations sont présentées dans le présent travail. Les caractéristiques de l'instrument y sont également décrites. Un algorithme d'inversion spectrale a été développé pour le cas spécifique de SOIR. Tenant compte du mode de mesure, l'occultation solaire, la méthode de la pelure d'oignons a été implémentée dans un algorithme dit de l'Estimation Optimale. Cette méthode permet d'inverser l'ensemble des mesures spectrales en une fois, et également d'en tirer d'autres informations, comme l'amélioration de certaines caractéristiques instrumentales. Les paramètres qui sont ajustés au sein de l'algorithme sont la densité de la ou des espèces absorbant dans la région spectrale concernée, la température, les paramètres de la ligne de base, qui permettent de déterminer les caractéristiques des aérosols, le déplacement Doppler des raies qui trouve principalement son origine dans la vitesse de déplacement du satellite, et l'amélioration de certaines calibrations. Une étude de sensibilité des différents paramètres de l'algorithme est également présentée, ainsi qu'une évaluation des erreurs instrumentales systématiques. Dans l'ensemble des spectres enregistrés durant les 4 premières années de la mission, des profils verticaux de CO2, CO, H2O, HDO, SO2, H2SO4, HCl et HF ont été obtenus. Des valeurs limites de densité de OCS, H2CO, O3 et CH4 ont également été calculées. Les résultats concernant le dioxyde de carbone sont développés dans le texte. Des profils verticaux de CO2 s'étendant de 70 km à 180 km d'altitude sont analysés en profondeur. Ils sont comparés aux profils dits hydrostatiques, et des hypothèses quant à la dynamique agissant au niveau des deux terminateurs de Vénus sont formulées. / Venus, second planet of the solar system, is often seen as the sister planet of the Earth. In terms of size and mass, they are indeed very similar, but the Venus atmosphere is much thicker and active. The altitude region extending from 70 km to 180~km is studied in this thesis, namely the mesosphere and the lower thermosphere. SOIR, which stands for Solar Occultation in the InfraRed, is a Russian / French / Belgian instrument flying on board of the Venus Express (VEX) spacecraft of the European Space Agency. The diffracting device of SOIR is an echelle grating. The wavenumber region studied ranges from 2200 cm-1 to 4400 cm-1, or 4.3 µm to 2.2 µm in wavelength. The diffraction orders used with SOIR vary from 101 to 194. To select the required echelle grating diffraction order, an Acousto-Optical Tunable Filter - AOTF - is located after the entrance slit of the instrument. The instrument resolution varies from 0.13 to 0.24 cm-1. SOIR was developed in a very short time. Thus, virtually all the calibrations had to be made in-flight. These concern the echelle grating (exact Blaze angle computation, Blaze function), the detector (pixel-to-pixel non-uniformity, spectral sensitivity curve, pixel-to-wavenumber relationship, instrument resolution, spectral sampling interval, signal-to-noise ratio, thermal background) and the AOTF (wavenumber to AOTF frequency relation, AOTF transfer function). The procedure for and the computation of these calibrations are described in this work, as well as the instrument characteristics. A spectral inversion algorithm was developed specifically for the SOIR measurement technique: the solar occultation. The onion peeling method is implemented using the Optimal Estimation Method. It allows the inversion of the spectral data in one go, and also the enhancement of some instrumental characteristics. The algorithm variables are the densities of the species absorbing in the diffraction order, the temperature of the atmosphere under study, the spectral background parameters, that allow the determination of the Venus aerosols characteristics, the Doppler shift (mainly linked to the shift induced by the satellite displacement), and the improvement of some instrumental calibrations. A sensitivity study on the algorithm parameters is also presented, and the instrumental systematic errors are investigated. Vertical profiles of CO2, CO, H2O, HDO, SO2, H2SO4, HCl and HF are derived from the spectra measured during the first 4 mission years. Upper limits on OCS, H2CO, O3 and CH4 have also been calculated. We focus on the carbon dioxide results in the present study. A selection of vertical profiles extending from 70 km to 180 km are analyzed in details. They are compared to the hydrostatic profiles, and propositions concerning the terminators' dynamics are formulated., Doctorat en Sciences de l'ingénieur, info:eu-repo/semantics/published
- Published
- 2011
12. Inversion of the infrared spectra recorded by the SOIR instrument on board Venus Express
- Author
-
Mahieux, Arnaud, Herman, Michel, Vandaele, Ann Carine, Degrez, Gérard, Biémont, Emile, Vander Auwera, Jean, Gérard, Jean-Claude, Godefroid, Michel, and Bertaux, Jean-Loup J.-L.
- Subjects
Vénus (Planète) -- Atmosphère ,Vénus ,Calibration ,Spectroscopie ,Mécanique ,Infrared spectra ,Spectre infrarouge ,Terminateur / Venus ,Terminator ,Sciences de l'ingénieur ,Venus (Planet) -- Atmosphere ,Spectroscopy - Abstract
Vénus, deuxième planète du système solaire, souvent appelée sœur de la Terre, car présentant des caractéristiques de taille et de masse similaires, est fort différente de notre planète. En effet, son atmosphère est beaucoup plus dense et dynamiquement active que celle de la Terre. Dans ce travail, nous nous concentrerons sur la région s'étendant de 70 km à 180~km d'altitude :la mésosphère et la basse thermosphère.SOIR, acronyme de Solar Occultation in the InfraRed, est un instrument russo-franco-belge embarqué à bord de la mission Venus Express de l'Agence Spatiale Européenne. Il utilise un réseau à échelle comme élément diffractant. La plage de nombre d'onde mesurable par SOIR s'étend de 2200 cm-1 à 4400 cm-1, ou 4.3 µm à 2.2 µm en longueur d'onde. Les ordres de diffraction utiles varient de 101 à 194. Un filtre acousto-optique - AOTF - est utilisé comme passe-bande pour sélectionner les ordres de diffraction. La résolution de l'instrument varie de 0.13 à 0.24 cm-1.Du fait d'un temps de développement raccourci, presque toutes les calibrations de l'instrument ont dû être réalisées en vol. Elles comprennent les calibrations relatives au réseau à échelle (angle exact de Blaze et fonction de Blaze), au détecteur (non-uniformité pixel à pixel, courbe de sensibilité spectrale, relation entre les pixels et les nombres d'onde, résolution de l'instrument, intervalle d'échantillonnage spectral, rapport signal sur bruit, background thermique) et à l'AOTF (relation entre la radio-fréquence d'excitation de l'AOTF et les nombres d'onde, fonction de transfert de l'AOTF). L'approche et la réalisation de ces différentes calibrations sont présentées dans le présent travail. Les caractéristiques de l'instrument y sont également décrites.Un algorithme d'inversion spectrale a été développé pour le cas spécifique de SOIR. Tenant compte du mode de mesure, l'occultation solaire, la méthode de la pelure d'oignons a été implémentée dans un algorithme dit de l'Estimation Optimale. Cette méthode permet d'inverser l'ensemble des mesures spectrales en une fois, et également d'en tirer d'autres informations, comme l'amélioration de certaines caractéristiques instrumentales. Les paramètres qui sont ajustés au sein de l'algorithme sont la densité de la ou des espèces absorbant dans la région spectrale concernée, la température, les paramètres de la ligne de base, qui permettent de déterminer les caractéristiques des aérosols, le déplacement Doppler des raies qui trouve principalement son origine dans la vitesse de déplacement du satellite, et l'amélioration de certaines calibrations. Une étude de sensibilité des différents paramètres de l'algorithme est également présentée, ainsi qu'une évaluation des erreurs instrumentales systématiques.Dans l'ensemble des spectres enregistrés durant les 4 premières années de la mission, des profils verticaux de CO2, CO, H2O, HDO, SO2, H2SO4, HCl et HF ont été obtenus. Des valeurs limites de densité de OCS, H2CO, O3 et CH4 ont également été calculées. Les résultats concernant le dioxyde de carbone sont développés dans le texte. Des profils verticaux de CO2 s'étendant de 70 km à 180 km d'altitude sont analysés en profondeur. Ils sont comparés aux profils dits hydrostatiques, et des hypothèses quant à la dynamique agissant au niveau des deux terminateurs de Vénus sont formulées./Venus, second planet of the solar system, is often seen as the sister planet of the Earth. In terms of size and mass, they are indeed very similar, but the Venus atmosphere is much thicker and active. The altitude region extending from 70 km to 180~km is studied in this thesis, namely the mesosphere and the lower thermosphere.SOIR, which stands for Solar Occultation in the InfraRed, is a Russian / French / Belgian instrument flying on board of the Venus Express (VEX) spacecraft of the European Space Agency. The diffracting device of SOIR is an echelle grating. The wavenumber region studied ranges from 2200 cm-1 to 4400 cm-1, or 4.3 µm to 2.2 µm in wavelength. The diffraction orders used with SOIR vary from 101 to 194. To select the required echelle grating diffraction order, an Acousto-Optical Tunable Filter - AOTF - is located after the entrance slit of the instrument. The instrument resolution varies from 0.13 to 0.24 cm-1.SOIR was developed in a very short time. Thus, virtually all the calibrations had to be made in-flight. These concern the echelle grating (exact Blaze angle computation, Blaze function), the detector (pixel-to-pixel non-uniformity, spectral sensitivity curve, pixel-to-wavenumber relationship, instrument resolution, spectral sampling interval, signal-to-noise ratio, thermal background) and the AOTF (wavenumber to AOTF frequency relation, AOTF transfer function). The procedure for and the computation of these calibrations are described in this work, as well as the instrument characteristics.A spectral inversion algorithm was developed specifically for the SOIR measurement technique: the solar occultation. The onion peeling method is implemented using the Optimal Estimation Method. It allows the inversion of the spectral data in one go, and also the enhancement of some instrumental characteristics. The algorithm variables are the densities of the species absorbing in the diffraction order, the temperature of the atmosphere under study, the spectral background parameters, that allow the determination of the Venus aerosols characteristics, the Doppler shift (mainly linked to the shift induced by the satellite displacement), and the improvement of some instrumental calibrations. A sensitivity study on the algorithm parameters is also presented, and the instrumental systematic errors are investigated.Vertical profiles of CO2, CO, H2O, HDO, SO2, H2SO4, HCl and HF are derived from the spectra measured during the first 4 mission years. Upper limits on OCS, H2CO, O3 and CH4 have also been calculated. We focus on the carbon dioxide results in the present study. A selection of vertical profiles extending from 70 km to 180 km are analyzed in details. They are compared to the hydrostatic profiles, and propositions concerning the terminators' dynamics are formulated., Doctorat en Sciences de l'ingénieur, info:eu-repo/semantics/nonPublished
- Published
- 2011
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