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Your search keyword '"Fouchet, Thierry"' showing total 11 results
Start Over Author "Fouchet, Thierry" Topic [phys.astr] physics [physics]/astrophysics [astro-ph]
11 results on '"Fouchet, Thierry"'

1. Investigation of the 2018 Global Dust Event from ACS-TIRVIM on board ExoMars/TGO

Author

Guerlet, Sandrine, Young, Roland, Ignatiev, Nikolay I., Forget, François, Millour, Ehouarn, Fouchet, Thierry, Montabone, Luca, Shakun, Alexey V., Grigoriev, Alexey, Trokhimovskiy, Alexander, Montmessin, Franck, Korablev, Oleg, and Henry, Florence

Subjects
[SDU] Sciences of the Universe [physics], [PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph]
Abstract

We report on the analysis of thermal infrared emission spectra recordedby ACS-TIRVIM on board the ExoMars Trace Gas Orbiter (TGO). We focus onthe period 13 March 2018 till 15 July 2018, covering quiescent and dustyconditions. From these observations, we retrieve temperature verticalprofiles from 5 to 45 km as well as integrated dust and water iceopacity at various local times. The retrieved temperature profiles arein excellent agreement with co-located observations by Mars ClimateSounder, a limb-viewing radiometer onboard Mars Reconnaissance Orbiter.The global dust event resulted in an up to 40K temperature increase inthe middle atmosphere. We will discuss these results compared to GlobalClimate Model (GCM) simulations run with MY34 dust scenario. We willalso present and discuss the atmospheric state resulting from theassimilation of TIRVIM temperature profiles into the LMD Mars GCM.

Published
2019

2. Pluto's atmosphere with ALMA: disk-resolved observations of CO and HCN, and first detection of HNC

Author

Lellouch, Emmanuel, Gurwell, Mark A., Moreno, Raphaël, Lavvas, Panayiotis, Butler, Bryan J., Strobel, Darell, Fouchet, Thierry, Moullet, Arielle, Bockelée-Morvan, Dominique, Biver, Nicolas, and Henry, Florence

Subjects
[PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph]
Abstract

Following our detection of HCN(4-3) and CO(3-2) in 2015 (Lellouch et al. 2017), we pursued our exploration of Pluto's atmosphere with ALMA. On July 30, 2017, we obtained maps of these CO and HCN emissions, with a 96 x 54 mas beam providing some spatial resolution of the Pluto disk in the North-South direction. On April 27, 2017, we explored portions of the 256.1-259.1 and 271.9-273.8 GHz spectrum, searching for HNC, CH3CN, and H13CN in disk-averaged observations. The highlight of this search was the detection of the HNC(3-2) line at 271.98 GHz, which appears as a narrow emission with a 15 mJy contrast. This first identification of HNC in Pluto's atmosphere reinforces the similarity to Titan's upper atmosphere, where HNC has been also observed (Moreno et al. 2011). Data interpretation in terms of (i) the spatial distribution of CO and HCN emissions (ii) the HNC abundance/vertical distribution, including comparison with photochemical models, will be presented.

Published
2018

3. First Measurements of Methyl Radical (CH3) in Jupiter's atmosphere using TEXES/IRTF and EXES/SOFIA

Author

Fouchet, Thierry, Greathouse, Thomas K., Bézard, Bruno, Richter, Matthew J., Moses, Julianne I., and Henry, Florence

Subjects
[PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph]
Abstract

We observed Jupiter with the TEXES instrument mounted on the IRTF telescope and the EXES instrument on board the SOFIA observatory in the range of methyl nu2 band at 16.5 mum. Both observations independently led to the detection of one or several lines of the methyl band. These observations, compared with synthetic spectra generated for several methyl vertical profiles, allows us to test photochemical models. Indeed, methyl recombination is the highly dominant pathway for the production of the most abundant photochemical product in Jupiter's atmosphere, ethane. Hence, this first measurement of methyl provides strong constraints on photochemical productions of heavy hydrocarbons in Jupiter's atmosphere.

Published
2018

4. Modeling the CH4 3.3 µm non-LTE emissions in Jupiter and Saturn

Author

Panka, Peter, Fouchet, Thierry, Kutepov, Alexander, Rezac, Ladislav, Feofilov, Artem, Janches, Diego, and Henry, Florence

Subjects
[PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph]
Abstract

The homopause divides planetary atmospheres into the high-pressure region where chemical species are well mixed by eddy diffusion and the low-pressure region where molecular diffusion separates species according to their individual masses. In Jupiter and Saturn, the homopause pressure level controls the methane abundance vertical profile, as methane is heavier than the two dominant species, H2 and He. Methane plays a critical role in establishing the thermal structure on these planets. It is the prime near-infrared absorber that warms the Jovian and Kronian upper atmospheres, and its photolysis by solar UV radiation triggers the production of ethane, acetylene, and heavier hydrocarbons that are the prime far-infrared coolants in these upper atmospheres. Hence the homopause level drives the heating rates, and, as ethane is mainly produced by the three-body methyl recombination (2CH3 M -> C2H6 M) whose reaction rate highly varies with pressure, the homopause level also controls the cooling rates. The determination of the methane homopause level in Jupiter and Saturn through solar occultations has been notoriously difficult as different studies and authors led to different results (see Moses et al. (2004), Fouchet et al. (2009) for reviews). Greathouse et al. (2010) even suggested that the Jovian homopause might vary spatially and/or temporally. Here we present a detailed non-LTE model of CH4 3.3 µm emissions for Jupiter and Saturn's atmosphere. The model accounts for various mechanisms of non-thermal excitation of CH4 molecules as well as inter- and intra-molecular vibrational-vibrational (VV) and vibrational-translational (VT) energy exchanges. With the help of this model, we studied the sensitivity of CH4 3.3 µm emissions to the temperature and methane abundance vertical profiles and compared integrated radiances with the corresponding Infrared Space Observatory (ISO) observations. We will discuss implications of these results to the interpretation of the homopause pressure level as well as opportunities the JWST telescope will provide to map the homopause across both planets.

Published
2018

5. Thermal structure and aerosol content in the martian atmosphere from ACS-TIRVIM onboard ExoMars/TGO

Author

Guerlet, Sandrine, Ignatiev, Nikolay I., Fouchet, Thierry, Forget, François, Millour, Ehouarn, Young, Roland, Montabone, Luca, Grigoriev, Alexey, Trokhimovskiy, Alexander, Montmessin, Franck, Korablev, Oleg, and Henry, Florence

Subjects
[PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph]
Abstract

The ExoMars Trace Gas Orbiter (TGO), a mission by ESA and Roscosmos, was launched in March 2016. After a long aerobraking phase, it reached its final, near-circular 400 km orbit in February, 2018 then started its operational scientific phase in March, 2018. On board TGO, the ACS-TIRVIM instrument has the capability to map the thermal structure of the Martian atmosphere and its aerosol load at a great variety of local times. In this abstract, we describe our retrieval algorithm used to analyse TIRVIM data. We discuss synthetic retrievals performed for a great variety of scenes to fine-tune and evaluate the performance of our algorithm, then present results obtained from the first orbits of TGO. In a second step (see EPSC abstract by Young et al.), the climatology dataset obtained from TIRVIM will be assimilated into the LMD Mars General Circulation Model to improve our understanding of the Martian atmospheric system.

Published
2018

6. Emission from Pluto and Charon at Long Wavelengths: Observations using ALMA, SMA, and VLA

Author

Butler, Bryan J., Gurwell, Mark A., Lellouch, Emmanuel, Moullet, Arielle, Biver, Nicolas, Bockelée-Morvan, Dominique, Boissier, Jérémie, Fouchet, Thierry, Lis, Darek C., Moreno, Raphaël, Stansberry, John A., Stern, S. A., Young, E. F., Young, Leslie A., Weaver, Harold A., and Henry, Florence

Subjects
[PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph]
Abstract

We report on the first Earth-based observations of thermal emission from the surfaces of Pluto and Charon where the two are resolved from each other. Observations at wavelengths from 0.8 mm to 0.9 cm with the Atacama Large Millimeter/submillimeter Array (ALMA), Submillimeter Array (SMA), and Karl G. Jansky Very Large Array (VLA) provide separate, high SNR flux densities for both bodies, which are converted into brightness temperatures. These observations have been presented separately previously [1-3] but here we combine them for the first time and extend the analysis. For Pluto, brightness temperatures range from 31--33 K, and for Charon from 42--45 K, over the full range of observed wavelengths. These brightness temperatures are significantly lower than observed surface temperatures for both bodies. While hinted at from unresolved observations of the pair, this is the first definitive observation showing both bodies have depressed brightness temperatures. These low brightness temperatures are likely due to a combination of low thermal inertia, and subsurface scattering, with a larger depression for Pluto than for Charon.[1] Butler et al. 2015, BAAS #47, id.210.04. [2] Gurwell et al. 2011, DPS/EPSC, p271. [3] Butler et al. 2011, DPS/EPSC, p. 1670.

Published
2017

7. Measuring molecular abundance profiles from 5 microns ground-based spectroscopy in support of JUNO investigations

Author

Blain, Doriann, Fouchet, Thierry, Encrenaz, Thérèse, Drossart, Pierre, Greathouse, Thomas K., Orton, Glenn S., Fletcher, Leigh N., Henry, Florence, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Planétologie du LESIA, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Southwest Research Institute [San Antonio] (SwRI), Jet Propulsion Laboratory, California Institute of Technology (JPL), and University of Leicester

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], [PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience; We report on early results of an observational campaign to support the Juno mission. At the beginning of 2015, using TEXES (Texas Echelon cross-dispersed Echelle Spectrograph), mounted on the NASA Infrared Telescope Facility (IRTF), we obtained data cubes of Jupiter in several spectral ranges between 2100 and 2200 cm-1 (4.5 - 4.7 mum) which probes the atmosphere in the 1-4 bar region, with a spectral resolution of R ≈ 7000 and an angular resolution of ≈ 1.5''. This dataset is analyzed by a code which combines a line-by-line radiative transfer model with a non-linear optimal estimation inversion method. The inversion takes into account the abundance profiles of AsH_3, CO, GeH4 and H_2O, as well as clouds contribution, in addtion to the abundance profiles of NH3 and PH_3. We will present the inverted abundance profiles, the spatial distribution of the molecular abundances, their significance for the understanding of Jupiter's atmospheric dynamics, and how this will be useful for the determination of water abundance up to 200 bars, which is one of the main objectives of the instrument MWR (MicroWave Radiometer) mounted on the Juno spacecraft. This work will also be useful to prepare the analysis of the JIRAM (Jovian InfraRed Auroral Mapper) 5-microns data aboard Juno.

Published
2017

8. Seasonal changes in Saturn's stratosphere from Cassini/CIRS data

Author

Sylvestre, Mélody, Fouchet, Thierry, Guerlet, Sandrine, Spiga, Aymeric, Flasar, Michael, Hesman, B. E., Bjoraker, Gordon L., Henry, Florence, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Planétologie du LESIA, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], [PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience

Published
2013

9. Global climate modeling of Saturn's atmosphere: fast and accurate radiative transfer and exploration of seasonal variability

Author

Guerlet, Sandrine, Spiga, Aymeric, Sylvestre, Mélody, Fouchet, Thierry, Millour, Ehouarn, Wordsworth, Robin, Leconte, Jeremy, Forget, François, Henry, Florence, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Planétologie du LESIA, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], [PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience

Published
2013

10. Meteor activities within Europlanet

Author

Oberst, Jürgen, Christou, Apostolos, Gritsevich, Maria I., Margonis, Anastasios, Koschny, Detlef, Heward, Anita, Fouchet, Thierry, Roggemans, P., Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Planétologie du LESIA, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), and Henry, Florence

Subjects
[PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience

Published
2012

11. Ground-based Infrared Observations of Water Vapor and Hydrogen Peroxide in the Atmosphere of Mars Near Summer Solstice

Author

Encrenaz, Thérèse, Greathouse, Thomas K., Bitner, M., Krüger, A., Lacy, John H., Richter, Matthew J., Bézard, Bruno, Fouchet, Thierry, Lefèvre, Franck, Forget, François, Atreya, Sushil K., Henry, Florence, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Planétologie du LESIA, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Service d'aéronomie (SA), 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), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], [PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience

Published
2008

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