185 results on '"Clancy, R. Todd"'
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2. Strong variability of Martian water ice clouds during dust storms revealed from ExoMars Trace Gas Orbiter/NOMAD
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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.
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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
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- 2019
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3. Water vapor saturation and ice cloud occurrence in the atmosphere of Mars
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Poncin, Loïc, Kleinböhl, Armin, Kass, David M., Clancy, R. Todd, Aoki, Shohei, and Vandaele, Ann Carine
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- 2022
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4. Detection and Quantification of Volatiles at Mars using a multispectral LIDAR
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Brown, Adrian J., Michaels, Timothy, Fenton, Lori, Hayne, Paul O., Piqueux, Sylvain, Titus, Timothy N., Wolff, Michael J., Clancy, R. Todd, Videen, Gorden, Sun, Wenbo, Haberle, Robert, Colaprete, Anthony, Richardson, Mark I., Byrne, Shane, Dissly, Richard, Beck, Steve, and Grund, Chris
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Astrophysics - Earth and Planetary Astrophysics - Abstract
We present a concept for using a polarization sensitive multispectral lidar to map the seasonal distribution and exchange of volatiles among the reservoirs of the Martian surface and atmosphere. The LIDAR instrument will be a multi-wavelength, altitude-resolved, active near-infrared (NIR, with 10 bands around 1.6 microns) instrument to measure the reflected intensity and polarization of backscattered radiation from planetary surfaces and atmospheres. The proposed instrument would be ideally suited for a mission to Mars to comprehensively investigate the nature and seasonal distributions of volatiles and aerosols. The investigation would include the abundance of atmospheric dust and condensed volatiles, surface and cloud/aerosol grain sizes and shapes, ice and dust particle microphysics and also variations in atmospheric chemistry during multiple overflight local times throughout polar night and day. Such an instrument would be ideal for mapping and detection of recently detected CO2 frost phenomena and H2O and CO2 precipitation events in the polar regions of Mars. Herein we discuss the applicability of this instrument to detect and map sublimation/deposition 'mode flips' recently discovered by Brown et al. (2016) using the CRISM passive infrared sensor on Mars Reconnaissance Orbiter., Comment: 9 pages, 3 figures
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- 2016
5. Mars perihelion cloud trails as revealed by MARCI: Mesoscale topographically focused updrafts and gravity wave forcing of high altitude clouds
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Clancy, R. Todd, Wolff, Michael J., Heavens, Nicholas G., James, Philip B., Lee, Steven W., Sandor, Brad J., Cantor, Bruce A., Malin, Michael C., Tyler, Daniel, Jr., and Spiga, Aymeric
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- 2021
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6. Heterogeneous Processes in the Atmosphere of Mars and Impact on H2O2 and O3 Abundances
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Daerden, Frank, primary, Crowley, John N., additional, Neary, Lori, additional, Smith, Michael D., additional, Loeffler, Mark J., additional, Clancy, R. Todd, additional, Wolff, Michael J., additional, Aoki, Shohei, additional, and Sagawa, Hideo, additional
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- 2023
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7. Mapping water ice clouds on Mars with MRO/MARCI
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Wolff, Michael J., Clancy, R. Todd, Kahre, Melinda A., Haberle, Robert M., Forget, François, Cantor, Bruce A., and Malin, Michael C.
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- 2019
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8. The distribution, composition, and particle properties of Mars mesospheric aerosols: An analysis of CRISM visible/near-IR limb spectra with context from near-coincident MCS and MARCI observations
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Clancy, R. Todd, Wolff, Michael J., Smith, Michael D., Kleinböhl, Armin, Cantor, Bruce A., Murchie, Scott L., Toigo, Anthony D., Seelos, Kim, Lefèvre, Franck, Montmessin, Franck, Daerden, Frank, and Sandor, Brad J.
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- 2019
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9. First Atmospheric Science Results from the Mars Exploration Rovers Mini-TES
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Smith, Michael D., Wolff, Michael J., Lemmon, Mark T., Spanovich, Nicole, Banfield, Don, Budney, Charles J., Clancy, R. Todd, Ghosh, Amitabha, Landis, Geoffrey A., Smith, Peter, Whitney, Barbara, Christensen, Philip R., and Squyres, Steven W.
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- 2004
10. The CRISM investigation in Mars orbit: Overview, history, and delivered data products
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Seelos, Frank P., primary, Seelos, Kimberly D., additional, Murchie, Scott L., additional, Novak, M. Alexandra Matiella, additional, Hash, Christopher D., additional, Morgan, M. Frank, additional, Arvidson, Raymond E., additional, Aiello, John, additional, Bibring, Jean-Pierre, additional, Bishop, Janice L., additional, Boldt, John D., additional, Boyd, Ariana R., additional, Buczkowski, Debra L., additional, Chen, Patrick Y., additional, Clancy, R. Todd, additional, Ehlmann, Bethany L., additional, Frizzell, Katelyn, additional, Hancock, Katie M., additional, Hayes, John R., additional, Heffernan, Kevin J., additional, Humm, David C., additional, Itoh, Yuki, additional, Ju, Maggie, additional, Kochte, Mark C., additional, Malaret, Erick, additional, McGovern, J. Andrew, additional, McGuire, Patrick, additional, Mehta, Nishant L., additional, Moreland, Eleanor L., additional, Mustard, John F., additional, Nair, A. Hari, additional, Núñez, Jorge I., additional, O'Sullivan, Joseph A., additional, Packer, Liam L., additional, Poffenbarger, Ryan T., additional, Poulet, Francois, additional, Romeo, Giuseppe, additional, Santo, Andrew G., additional, Smith, Michael D., additional, Stephens, David C., additional, Toigo, Anthony D., additional, Viviano, Christina E., additional, and Wolff, Michael J., additional
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- 2023
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11. The thermal structure of the Venus atmosphere: Intercomparison of Venus Express and ground based observations of vertical temperature and density profiles
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Limaye, Sanjay S., Lebonnois, Sebastien, Mahieux, Arnaud, Pätzold, Martin, Bougher, Steven, Bruinsma, Sean, Chamberlain, Sarah, Clancy, R. Todd, Gérard, Jean-Claude, Gilli, Gabriella, Grassi, Davide, Haus, Rainer, Herrmann, Maren, Imamura, Takeshi, Kohler, Erika, Krause, Pia, Migliorini, Alessandra, Montmessin, Franck, Pere, Christophe, Persson, Moa, Piccialli, Arianna, Rengel, Miriam, Rodin, Alexander, Sandor, Brad, Sornig, Manuela, Svedhem, Håkan, Tellmann, Silvia, Tanga, Paolo, Vandaele, Ann C., Widemann, Thomas, Wilson, Colin F., Müller-Wodarg, Ingo, and Zasova, Ludmila
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- 2017
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12. Heterogeneous Processes in the Atmosphere of Mars and Impact on H2O2 and O3 Abundances.
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Daerden, Frank, Crowley, John N., Neary, Lori, Smith, Michael D., Loeffler, Mark J., Clancy, R. Todd, Wolff, Michael J., Aoki, Shohei, and Sagawa, Hideo
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MARTIAN atmosphere ,ATMOSPHERE ,GENERAL circulation model ,MINERAL dusts ,ATMOSPHERIC chemistry ,ICE clouds - Abstract
Current models underestimate the highest observed ozone (O3) column densities on Mars. These estimates could be improved by including the uptake of odd hydrogen species (HOx) on water ice clouds, but the reported uptake coefficient of HO2 is likely overestimated for atmospheric conditions. This leaves a fundamental problem in Mars' atmospheric chemistry unsolved. Here, using the GEM‐Mars general circulation model, we explore a range of processes involving multiple phases (gas, adsorbed and solid) that may contribute to an alternative solution. First, we focus on hydrogen peroxide (H2O2) and discuss its physical states on Mars and its chemical impact. We also conjecture its photolytic destruction in ices with model simulations and Compact Reconnaissance Imaging Spectrometer for Mars observations. Then, we include in the model all relevant (for Mars) heterogeneous reactions, both on dust and water ice, recommended by the International Union of Pure and Applied Chemistry for terrestrial atmospheric studies. We find that only the uptake of HO2 and H2O2 on dust are efficient on Mars. Finally, we find that attenuation of sunlight by water ice clouds in the calculation of photolysis rates leads to increased O3 and H2O2 abundances below the ice clouds. The combination of the proposed processes leads to O3 increases without the need for strong uptake of HO2 on ice, but it remains difficult to find a good agreement with O3 and H2O2 observations on the global scale. We provide specific recommendations for future work in observations, laboratory experiments and modeling to advance our understanding of fundamental chemistry on Mars. Plain Language Summary: After decades of observations and numerical modeling, there remain persistent problems in our understanding of atmospheric chemistry on Mars. One of these is the underestimation of the highest ozone abundances by models, on which we focus here. It was demonstrated that uptake of HO2 on water ice could improve this, but we argue that the experimentally obtained reaction rate is too large. We present a range of other processes that can contribute to solving the Mars ozone problem, and implement them in a 3D atmospheric model. We investigate the low temperature behavior of H2O2 on Mars and its impact on ozone, and demonstrate that H2O2 is destroyed in surface ices. This is supported by a first search for H2O2 in surface ices on Mars. We also test all heterogeneous reactions on dust and water ice that are recommended for the terrestrial atmosphere, and find that the uptake of HO2 and H2O2 by mineral dust could be efficient on Mars. Finally, we find that the shielding of incoming sunlight by water ice clouds leads to larger ozone abundances below the clouds. Combining these processes improves the ozone simulation, but more refinements are still needed in observations, laboratory experiments and modeling. Key Points: Uptake of HO2 on water ice on Mars could improve ozone simulations, but its unreliable support urges searches for alternative processesWe introduce a range of new heterogeneous processes in a Mars general circulation model and evaluate their impact on ozone and H2O2We discuss the physical states of H2O2 on Mars, its photolytic destruction in ice, and the uptake of H2O2 and HO2 by mineral dust [ABSTRACT FROM AUTHOR]
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- 2023
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13. Unique Spectroscopy and Imaging of Mars with the James Webb Space Telescope
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Villanueva, Gerónimo L., Altieri, Francesca, Clancy, R. Todd, Encrenaz, Therese, Fouchet, Thierry, Hartogh, Paul, Lellouch, Emmanuel, Lopéz-Valverde, Miguel A., Mumma, Michael J., Novak, Robert E., Smith, Michael D., Vandaele, Ann-Carine, Wolff, Michael J., Ferruit, Pierre, and Milam, Stefanie N.
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- 2016
14. Doppler winds mapped around the lower thermospheric terminator of Venus: 2012 solar transit observations from the James Clerk Maxwell Telescope
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Clancy, R. Todd, Sandor, Brad J., and Hoge, James
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- 2015
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15. History of Mars Atmosphere Observations
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James, Philip B., primary, Christensen, Philip R., additional, Clancy, R. Todd, additional, Lemmon, Mark T., additional, and Withers, Paul, additional
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- 2017
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16. Mars Clouds
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Clancy, R. Todd, primary, Montmessin, Franck, additional, Benson, Jennifer, additional, Daerden, Frank, additional, Colaprete, Anthony, additional, and Wolff, Michael J., additional
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- 2017
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17. Observations of HCl altitude dependence and temporal variation in the 70–100 km mesosphere of Venus
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Sandor, Brad J. and Clancy, R. Todd
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- 2012
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18. Publisher Correction: Martian dust storm impact on atmospheric H2O and D/H observed by ExoMars Trace Gas Orbiter
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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
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- 2019
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19. Vertical Profiles of Mars 1.27 Micrometer O2 Dayglow from MRO CRISM Limb Spectra: Seasonal/global Behaviors, Comparisons to LMDGCM Simulations, and a Global Definition for Mars Water Vapor Profiles
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Clancy, R. Todd, Smith, Michael D, Lefevre, Franck, McConnochie, Timothy H, Sandor, Brad J, Wolff, Michael J, Lee, Steven W, Murchie, Scott L, Toigo, Anthony D, Nair, Hari, and Navarro, Thomas
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Lunar And Planetary Science And Exploration - Abstract
Since July of 2009, The Compact Reconnaissance Imaging Spectral Mapper (CRISM) onboard the Mars Re- connaissance Orbiter (MRO) has periodically obtained pole-to-pole observations (i.e., full MRO orbits) of limb scanned visible/near IR spectra (lambda= 0.4 - 4.0 micrometers, delta lambda approx. 10 nm- Murchie et al., 2007). These CRISM limb observations support the first seasonally and spatially extensive set of Mars 1.27 micometers O2 (1 delta(sub g)) day-glow profile retrievals (approx. 1100) over greater than or equal to 8-80 km altitudes. Their comparison to Laboratoire de Meteorologie Dynamique (LMD) global climate model (GCM) simulated O2 (1 delta(sub g)) volume emission rate (VER) profiles, as a function of altitude, latitude, and season (solar longitude, L(sub s), supports several key conclusions regarding Mars atmospheric water vapor (which is derived from O2 (1 delta(sub g)) emission rates), Mars O3, and the collisional de-excitation of O2 (1 delta(sub g)) in the Mars CO2 atmosphere. Current (Navarro et al., 2014) LMDGCM simulations of Mars atmospheric water vapor fall 2-3 times below CRISM derived water vapor abundances at 20-40 km altitudes over low-to-mid latitudes in northern spring (L(sub s) = 30-60 deg), and northern mid-to-high latitudes over northern summer (L(sub s) = 60-140 deg). In contrast, LMDGCM simulated water vapor is 2-5 times greater than CRISM derived values at all latitudes and seasons above 40 km, within the aphelion cloud belt (ACB), and over high-southern to mid-southern latitudes in southern summer (L(sub s) = 190-340 deg) at 15-35 km altitudes. Overall, the solstitial summer-to-winter hemisphere gradients in water vapor are reversed between the LMDGCM modeled versus the CRISM derived water vapor abundances above 10-30 km altitudes. LMDGCM-CRISM differences in water vapor profiles correlate with LMDGCM-CRISM differences in cloud mixing profiles; and likely reflect limitations in simulating cloud microphysics and radiative forcing, both of which restrict meridional transport of water from summer- to-winter hemispheres on Mars (Clancy et al., 1996; Montmessin et al., 2004; Steele et al., 2014; Navarro et al., 2014) and depend on uncertain cloud microphysical properties (Navarro et al., 2014). The derived low-to-mid latitude changes in Mars water vapor vertical distributions should reduce current model- data disagreements in column O3 and H2O2 abundances over low-to-mid latitudes (e.g., within the ACB; Lefevre et al., 2008; Encrenaz et al., 2015; Clancy et al., 2016). Lastly, the global/seasonal average com- parison of CRISM and LMDGCM O2 (1 delta(sub g)) VER below 20 km altitudes indicates a factor of approx. 3 times lower value (0.25 x 10(exp -20) cu cm sec(exp -1)) for the CO2 collisional de-excitation rate coefficient of O2 (1 delta(sub g)) than derived recently by Guslyakova et al. (2016).
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- 2017
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20. First Detection and Thermal Characterization of Terminator CO 2 Ice Clouds With ExoMars/NOMAD
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Liuzzi, Giuliano, primary, Villanueva, Geronimo L., additional, Trompet, Loïc, additional, Crismani, Matteo M. J., additional, Piccialli, Arianna, additional, Aoki, Shohei, additional, Lopez‐Valverde, Miguel Angel, additional, Stolzenbach, Aurélien, additional, Daerden, Frank, additional, Neary, Lori, additional, Smith, Michael D., additional, Patel, Manish R., additional, Lewis, Stephen R., additional, Clancy, R. Todd, additional, Thomas, Ian R., additional, Ristic, Bojan, additional, Bellucci, Giancarlo, additional, Lopez‐Moreno, Jose‐Juan, additional, and Vandaele, Ann Carine, additional
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- 2021
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21. Daily Global Mapping of Mars Ozone Column Abundances with MARCI UV Band Imaging
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Clancy, R. Todd, Wolff, Michael J, Lefevre, Franck, Cantor, Bruce A, Malin, Michael C, and Smith, Michael D
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Lunar And Planetary Science And Exploration - Abstract
Since November of 2006, The Mars Color Imager (MARCI) onboard the Mars Reconnaissance Orbiter (MRO) has obtained multiple-filter daily global images of Mars centered upon a local time (LT) of 3 pm. Ultraviolet imaging bands placed within (260 nm) and longward (320 nm) of Hartley band (240-300 nm) ozone (O3) absorption support retrievals of atmospheric ozone columns, with detection limits (approximately 1 micrometer-atm) appropriate to mapping elevated O3 abundances at low latitudes around Mars aphelion, and over mid-to-high latitudes during fall/winter/spring seasons. MARCI O3 maps for these regions reveal the detailed spatial (approximately 1 deg lat/long, for 8 x 8 pixel binned resolution) and temporal (daily, with substantial LT coverage at pole) behaviors of water vapor saturation conditions that force large variations in water vapor photolysis products (HOx-OH, HO2, and H) responsible for the catalytic destruction of O3 in the Mars atmosphere. A detailed description of the MARCI O3 data set, including measurement and retrieval characteristics, is provided in conjunction with comparisons to Mars Express SPICAM ozone measurements (Perrier, S. et al. [2006]. J. Geophys. Res. (Planets) 111) and LMD GCM simulated O3 abundances (Lefevre, F. [2004]. J. Geophys. Res. (Planets) 109). Presented aspects of the MARCI ozone mapping data set include aphelion increases in low latitude O3, dynamically evolving high latitude O3 maxima associated with planetary waves and weather fronts during northern early spring, and distinctive winter/spring O3 and CO increases within the Hellas Basin associated with transport of condensation enhanced south polar air mass. Comparisons of coincident MARCI measurements and LMD simulations for ice cloud and O3 columns are considered in the context of potential heterogeneous photochemical processes (Lefevre, F. [2008]. Nature 454, 971-975), which are not strongly evidenced in the MARCI observations. Modest interannual variations are exhibited, most notably a 20% reduction in aphelion low latitude O3 columns following the 2007 perihelic global dust storm.
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- 2015
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22. Sulfur chemistry in the Venus mesosphere from SO.sub.2 and SO microwave spectra
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Sandor, Brad J., Clancy, R. Todd, Moriarty-Schieven, Gerald, and Mills, Franklin P.
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Sulfates -- Analysis ,Astronomy -- Analysis ,Sulfuric acid -- Analysis ,Sulfur -- Analysis ,Atmosphere -- Analysis ,Earth -- Atmosphere ,Earth -- Analysis ,Astronomy ,Earth sciences - Abstract
To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2010.02.013 Byline: Brad J. Sandor (a), R. Todd Clancy (a)(b), Gerald Moriarty-Schieven (c), Franklin P. Mills (d) Keywords: Venus, Atmosphere; Photochemistry; Atmospheres, Chemistry; Atmospheres, Composition; Abundances, Atmospheres Abstract: First measurements of SO.sub.2 and SO in the Venus mesosphere (70-100km) are reported. This altitude range is distinctly above the [approximately equal to]60-70km range to which nadir-sounding IR and UV investigations are sensitive. Since July 2004, use of ground-based sub-mm spectroscopy has yielded multiple discoveries. Abundance of each molecule varies strongly on many timescales over the entire sub-Earth Venus hemisphere. Diurnal behavior is evident, with more SO.sub.2, and less SO, at night than during the day. Non-diurnal variability is also present, with measured SO.sub.2 and SO abundances each changing by up to 2x or more between observations conducted on different dates, but at fixed phase, hence identical sub-Earth Venus local times. Change as large and rapid as a 5I doubling of SO on a one-week timescale is seen. The sum of SO.sub.2 and SO abundances varies by an order of magnitude or more, indicating at least one additional sulfur reservoir must be present, and that it must function as both a sink and source for these molecules. The ratio SO.sub.2/SO varies by nearly two orders of magnitude, with both diurnal and non-diurnal components. In contrast to the strong time dependence of molecular abundances, their altitude distributions are temporally invariant, with far more SO.sub.2 and SO at 85-100km than at 70-85km. The observed increase of SO.sub.2 mixing ratio with altitude requires that the primary SO.sub.2 source be upper mesospheric photochemistry, contrary to atmospheric models which assert upward transport as the only source of above-cloud SO.sub.2. Abundance of upper mesospheric aerosol, with assumption that it is composed primarily of sulfuric acid, is at least sufficient to provide the maximum gas phase (SO+SO.sub.2) sulfur reported in this study. Sulfate aerosol is thus a plausible source of upper mesospheric SO.sub.2. Author Affiliation: (a) Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301, United States (b) Space Science Institute, P.O. Box 3075, Bald Head Island, NC 28461, United States (c) National Research Council of Canada, Joint Astronomy Centre, 660 North Aohoku Place, Hilo, HI 96720, United States (d) RSPE/AMPL, Mills Rd., Australian National University, Canberra, ACT 0200, Australia Article History: Received 6 November 2009; Revised 18 February 2010; Accepted 19 February 2010
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- 2010
23. Ultraviolet dust aerosol properties as observed by MARCI
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Wolff, Michael J., Clancy, R. Todd, Goguen, Jay D., Malin, Michael C., and Cantor, Bruce A.
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Mars (Planet) -- Analysis ,Astronomy -- Analysis ,Sandstorms -- Analysis ,Planets -- Atmosphere ,Planets -- Analysis ,Astronomy ,Earth sciences - Abstract
To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2010.01.010 Byline: Michael J. Wolff (a), R. Todd Clancy (a), Jay D. Goguen (b), Michael C. Malin (c), Bruce A. Cantor (c) Keywords: Mars, Atmosphere; Ultraviolet observations; Radiative transfer Abstract: Observations by the Mars Color Imager (MARCI) on board the Mars Reconnaissance Orbiter (MRO) in two ultraviolet (UV, Bands 6 and 7; 258nm, and 320nm, respectively) and one visible (Band 1, 436nm) channels of the 2007 planet encircling dust storm are combined with those made by the two Mars Exploration Rovers (MERs) to better characterize the single scattering albedo (I.sub.0) of martian dust aerosols. Exploiting the low contrast of the surface in the UV (and blue) as well as the reduced importance of surface reflectance under very dusty conditions, we utilize the sampling of photometric angles by the MARCI cross-track geometry to synthesize an analog of the classical Emergence Phase Function (EPF). This so-called 'pseudo-EPF', used in conjunction with the 'ground-truth' measurements provided by the MERs, is able to effectively isolate the effects of the dust I.sub.0. The motivation for this approach is the elimination of a significant portion of the type of uncertainty involved in many previous radiative transfer analyses. Furthermore, we produce a self-consistent set of complex refractive indices (m=n+ik) through our use of an explicit microphysical representation of the aerosol scattering properties. Because of uncertainty in the exact size of the dust particles during the epoch of the observations, we consider two effective particle radii (r.sub.eff) to cover the range anticipated from the literature: 1.6 and 1.8[mu]m. The resulting set of model-data comparisons, I.sub.0, and m are presented along with an assessment of potential sources of error and uncertainty. Analysis of the Band 1 results is limited to I.sub.0 as a 'proof-of-concept' for our approach through a comparison to contemporaneous CRISM EPF results at 440nm. The derived I.sub.0 are: assuming r.sub.eff=1.6[mu]m-0.619-0.626,0.648, and 0.765, for Bands 6, 7, and 1, respectively; for r.sub.eff=1.8[mu]m-0.625-0.635,0.653,0.769, for the same band order. For either r.sub.eff case, the total estimated error is 0.022, 0.019, and 0.010, again for Bands 6, 7, and 1. We briefly discuss our retrievals, including the asymmetry parameter (g) associated with our model phase functions, within the context of previous efforts, with an emphasis on the improved precision of our results compared to those in the literature. We also suggest several applications of our results, including an extension of the dust climatological record using MARCI Band 7 pseudo-EPFs outside of 2007 global dust event. Initial work on this particular application using a sample of 135 pseudo-EPFs near the MERs suggests that optical depth retrievals with a precision in the range 0.2-0.4 may be possible under moderate loading conditions (i.e., I Author Affiliation: (a) Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301, USA (b) Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109, USA (c) Malin Space Science Systems, P.O. Box 910149, San Diego, CA 92191, USA Article History: Received 20 August 2009; Revised 11 January 2010; Accepted 13 January 2010
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- 2010
24. Extension of atmospheric dust loading to high altitudes during the 2001 Mars dust storm: MGS TES limb observations
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Clancy, R. Todd, Wolff, Michael J., Whitney, Barbara A., Cantor, Bruce A., Smith, Michael D., and McConnochie, Timothy H.
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Mars (Planet) -- Analysis ,Astronomy -- Analysis ,Planets -- Atmosphere ,Planets -- Analysis ,Sandstorms -- Analysis ,Dust storms -- Analysis ,Astronomy ,Earth sciences - Abstract
To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2009.10.011 Byline: R. Todd Clancy (a), Michael J. Wolff (a), Barbara A. Whitney (a), Bruce A. Cantor (b), Michael D. Smith (c), Timothy H. McConnochie (c) Keywords: Mars, Atmosphere; Mars, Climate; Mars; Atmospheres, Structure; Abundances, Atmospheres Abstract: Mars Global Surveyor (MGS) visible (solarband bolometer) and thermal infrared (IR) spectral limb observations from the Thermal Emission Spectrometer (TES) support quantitative profile retrievals for dust opacity and particle sizes during the 2001 global dust event on Mars. The current analysis considers the behavior of dust lifted to altitudes above 30km during the course of this storm; in terms of dust vertical mixing, particle sizes, and global distribution. TES global maps of visible (solarband) limb brightness at 60km altitude indicate a global-scale, seasonally evolving (over 190-240[degrees] solar longitudes, L.sub.S) longitudinal corridor of vertically extended dust loading (which may be associated with a retrograde propagating, wavenumber 1 Rossby wave). Spherical radiative transfer analysis of selected limb profiles for TES visible and thermal IR radiances provide quantitative vertical profiles of dust opacity, indicating regional conditions of altitude-increasing dust mixing ratios. Observed infrared spectral (I'=5-40[mu]m) dependences and visible-to-infrared opacity ratios of dust scattering over 30-60km altitudes indicate particle sizes characteristic of lower altitudes (cross-section weighted effective radius, r.sub.eff=1.5-2.0[mu]m), during conditions of significant dust transport to these altitudes. Conditions of reduced dust loading at 30-60km altitudes present smaller dust particle sizes (r.sub.eff[approximately equal to]0.5-1.0[mu]m). These observations suggest rapid meridional transport at 30-80km altitudes, with substantial longitudinal variation, of dust lifted to these altitudes over southern hemisphere atmospheric regions characterized by extraordinary (m/s) vertical advection velocities. By L.sub.S=230[degrees] dust loading above 50km altitudes decreased markedly at southern latitudes, with a high altitude (60-80km) haze of fine (likely) water ice particles appearing over 10[degrees]S-40[degrees]N latitudes. Author Affiliation: (a) Space Science Institute, Boulder, CO, United States (b) Malin Space Science Systems, San Diego, CA, United States (c) NASA Goddard Space Flight Center, Greenbelt, MD, United States Article History: Received 10 June 2009; Revised 19 October 2009; Accepted 21 October 2009
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- 2010
25. MRO/CRISM retrieval of surface Lambert albedos for multispectral mapping of Mars with DISORT-based radiative transfer modeling: phase 1--using historical climatology for temperatures, aerosol optical depths, and atmospheric pressures
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McGuire, Patrick C., Wolff, Michael J., Smith, Michael D., Arvidson, Raymond E., Murchie, Scott L., Clancy, R. Todd, Roush, Ted L., Cull, Selby C., Lichtenberg, Kim A., Wiseman, Sandra M., Green, Robert O., Martin, Terry Z., Milliken, Ralph E., Cavender, Peter J., Humm, David C., Seelos, Frank P., Seelos, Kim D., Taylor, Howard W., Ehlmann, Bethany L., Mustard, John F., Pelkey, Shannon M., Titus, Timothy N., Hash, Christopher D., and Malaret, Erick R.
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Astrogeology -- Models ,Astrogeology -- Analysis ,Remote sensing -- Usage ,Remote sensing -- Analysis ,Albedo -- Analysis ,Paleoclimatology -- Models ,Paleoclimatology -- Analysis ,Mars (Planet) -- Atmosphere ,Mars (Planet) -- Observations ,Mars (Planet) -- Models ,Mars (Planet) -- Analysis ,Business ,Earth sciences ,Electronics and electrical industries - Abstract
We discuss the DISORT-based radiative transfer pipeline ('CRISM_LambertAlb') for atmospheric and thermal correction of MRO/CRISM data acquired in multispectral mapping mode (~200 m/pixel, 72 spectral channels). Currently, in this phase-one version of the system, we use aerosol optical depths, surface temperatures, and lower atmospheric temperatures, all from climatology derived from Mars Global Surveyor Thermal Emission Spectrometer (MGS-TES) data and from surface altimetry derived from MGS Mars Orbiter Laser Altimeter (MOLA). The DISORT-based model takes the dust and ice aerosol optical depths (scaled to the CRISM wavelength range), the surface pressures (computed from MOLA altimetry, MGS-TES lower atmospheric thermometry, and Viking-based pressure climatology), the surface temperatures, the reconstructed instrumental photometric angles, and the measured I/F spectrum as inputs, and then a Lambertian albedo spectrum is computed as the output. The Lambertian albedo spectrum is valuable geologically because it allows the mineralogical composition to be estimated. Here, I/F is defined as the ratio of the radiance measured by CRISM to the solar irradiance at Mars divided by [pi]; if there was no martian atmosphere, I/F divided by the cosine of the incidence angle would be equal to the Lambert albedo for a Lambertian surface. After discussing the capabilities and limitations of the pipeline software system, we demonstrate its application on several multispectral data cubes--particularly, the outer reaches of the northern ice cap of Mars, the Tyrrhena Terra area that is northeast of the Hellas basin, and an area near the landing site for the Phoenix mission in the northern plains. For the icy spectra near the northern polar cap, aerosols need to be included in order to properly correct for the C[O.sub.2] absorption in the [H.sub.2]O ice bands at wavelengths near 2.0 [micro]m. In future phases of software development, we intend to use CRISM data directly in order to retrieve the spatiotemporal maps of aerosol optical depths, surface pressure, and surface temperature. This will allow a second level of refinement in the atmospheric and thermal correction of CRISM multispectral data. Index Terms--Atmospheric propagation, infrared spectroscopy, remote sensing, software verification and validation.
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- 2008
26. Heterogeneous chemistry in the atmosphere of Mars
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Lefevre, Franck, Bertaux, Jean-Loup, Clancy, R. Todd, Encrenaz, Therese, Fast, Kelly, Forget, Francois, Lebonnois, Sebastien, Montmessin, Franck, and Perrier, Severine
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Chemical processes -- Research -- Chemical properties ,Atmosphere -- Research -- Chemical properties ,Earth -- Atmosphere -- Research -- Chemical properties ,Mars (Planet) -- Research -- Chemical properties ,Environmental issues ,Science and technology ,Zoology and wildlife conservation ,Chemical properties ,Research - Abstract
Hydrogen radicals are produced in the martian atmosphere by the photolysis of water vapour and subsequently initiate catalytic cycles that recycle carbon dioxide from its photolysis product carbon monoxide (1,2). [...]
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- 2008
27. Water vapor variations in the Venus mesosphere from microwave spectra
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Sandor, Brad J. and Clancy, R. Todd
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Astronomy ,Earth sciences - Abstract
To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2005.03.020 Byline: Brad J. Sandor (a), R. Todd Clancy (b) Keywords: Venus; atmosphere; Spectroscopy; Photochemistry; Atmospheres; composition; Atmospheres; structure Abstract: Mm-wave spectra of HDO in the Venus mesosphere (65-100 km) were obtained over the period March 1998 to June 2004. Each spectrum is a measurement of the hemispheric-average H.sub.2O vapor mixing ratio in the Venus mesosphere. Observations were conducted for wide ranges of Venus solar elongations (46[degrees] W to 47[degrees] E), and fractional disk illuminations (f=0% to 99%), yielding water vapor abundances on 17 dates and over a full range of local solar time (LST) at the sub-Earth point on Venus. Our mesopheric H.sub.2O values are more numerous and far more precise than the earliest mm-derived H.sub.2O measurements [Encrenaz, Th., Lellouch, E., Paubert, G., Gulkis, S., 1991. First detection of HDO in the atmosphere of Venus at radio wavelengths: An estimate of the H.sub.2O vertical distribution. Astron. Astrophys. 246, L63-L66; Encrenaz, Th., Lellouch, E., Cernicharo, J., Paubert, G., Gulkis, S., Spilker, T., 1995. The thermal profile and water abundance in the Venus mesosphere from H.sub.2O and HDO millimeter observations. Icarus 117, 162-172], allowing an analysis of variability that was previously impossible. Measured 65-100 km H.sub.2O ranged from 0.0[+ or -]0.06 to 3.5[+ or -]0.3ppmv, with significantly different variability than found in previous infrared (lower altitude, cloudtop) studies. Strong global variability on a 1-2 month timescale is clear and unambiguous. A limited number of excellent s/n measurements tentatively indicate the 1-2 month variability manifests most rapidly as change in the lower mesosphere, and more slowly as change in the upper mesosphere. Neither long term (1998-2004) nor diurnal variability in 65-100 km H.sub.2O is evident. While six-year and/or diurnal variabilities are not ruled out, they are weaker than the 1-2 month timescale variation. These conclusions are supported by initial (2004) sub-mm measurements. Author Affiliation: (a) Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301, USA (b) Space Science Institute, P.O. Box 3075, Bald Head Island, NC 28461, USA Article History: Received 3 November 2004; Revised 18 March 2005
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- 2005
28. Strong Variability of Martian Water Ice Clouds During Dust Storms Revealed From ExoMars Trace Gas Orbiter/NOMAD
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Liuzzi, Giuliano, primary, Villanueva, Geronimo L., additional, Crismani, Matteo M.J., additional, Smith, Michael D., additional, Mumma, Michael J., additional, Daerden, Frank, additional, Aoki, Shohei, additional, Vandaele, Ann Carine, additional, Clancy, R. Todd, additional, Erwin, Justin, additional, Thomas, Ian, additional, Ristic, Bojan, additional, Lopez‐Moreno, José‐Juan, additional, Bellucci, Giancarlo, additional, and Patel, Manish R., additional
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- 2020
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29. Extensive MRO CRISM Observations of 1.27 micron O2 Airglow in Mars Polar Night and Their Comparison to MRO MCS Temperature Profiles and LMD GCM Simulations
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Clancy, R. Todd, Sandor, Brad J, Wolff, Michael J, Smith, Michael Doyle, Lefevre, Franck, Madeleine, Jean-Baptiste, Forget, Francois, Murchie, Scott L, Seelos, Frank P, Seelos, Kim D, Nair, Hari A, Toigo, Anthony D, Humm, David, Kass, David M, Kleinbahl, Armin, and Heavens, Nicholas
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Lunar And Planetary Science And Exploration - Abstract
The Martian polar night distribution of 1.27 micron (0-0) band emission from O2 singlet delta [O2(1Delta(sub g))] is determined from an extensive set of Mars Reconnaissance Orbiter (MRO) Compact Reconnaissance Imaging Spectral Mapping (CRISM) limb scans observed over a wide range of Mars seasons, high latitudes, local times, and longitudes between 2009 and 2011. This polar nightglow reflects meridional transport and winter polar descent of atomic oxygen produced from CO2 photodissociation. A distinct peak in 1.27 micron nightglow appears prominently over 70-90NS latitudes at 40-60 km altitudes, as retrieved for over 100 vertical profiles of O2(1Delta(sub g)) 1.27 micron volume emission rates (VER). We also present the first detection of much (x80+/-20) weaker 1.58 micron (0-1) band emission from Mars O2(1Delta(sub g)). Co-located polar night CRISM O2(1Delta(sub g)) and Mars Climate Sounder (MCS) (McCleese et al., 2008) temperature profiles are compared to the same profiles as simulated by the Laboratoire de Météorologie Dynamique (LMD) general circulation/photochemical model (e.g., Lefèvre et al., 2004). Both standard and interactive aerosol LMD simulations (Madeleine et al., 2011a) underproduce CRISM O2(1Delta(sub g)) total emission rates by 40%, due to inadequate transport of atomic oxygen to the winter polar emission regions. Incorporation of interactive cloud radiative forcing on the global circulation leads to distinct but insufficient improvements in modeled polar O2(1Delta(sub g)) and temperatures. The observed and modeled anti-correlations between temperatures and 1.27 mm band VER reflect the temperature dependence of the rate coefficient for O2(1Delta(sub g)) formation, as provided in Roble (1995).
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- 2012
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30. Vertical Distribution of Aersols and Water Vapor Using CRISM Limb Observations
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Smith, Michael D, Wolff, Michael J, and Clancy, R. Todd
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Astronomy - Abstract
Near-infrared spectra taken in a limb-viewing geometry by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on-board the Mars Reconnaissance Orbiter (MRO) provide a useful tool for probing atmospheric structure. Specifically, the observed radiance as a function of wavelength and height above the limb allows the vertical distribution of both dust and ice aerosols to be retrieved. These data serve as an important supplement to the aerosol profiling provided by the MRO/MCS instrument allowing independent validation and giving additional information on particle physical and scattering properties through multi-wavelength studies. A total of at least ten CRISM limb observations have been taken so far covering a full Martian year. Each set of limb observations nominally contains about four dozen scans across the limb giving pole-to-pole coverage for two orbits at roughly 100 and 290 W longitude over the Tharsis and Syrtis/Hellas regions, respectively. At each longitude, limb scans are spaced roughly 10 degrees apart in latitude, with a vertical spatial resolution on the limb of roughly 800 m. Radiative transfer modeling is used to model the observations. We compute synthetic CRISM limb spectra using a discrete-ordinates radiative transfer code that accounts for multiple scattering from aerosols and accounts for spherical geometry of the limb observations by integrating the source functions along curved paths in that coordinate system. Retrieved are 14-point vertical profiles for dust and water ice aerosols with resolution of 0.4 scale heights between one and six scale heights above the surface. After the aerosol retrieval is completed, the abundances of C02 (or surface pressure) and H20 gas are retrieved by matching the depth of absorption bands at 2000 nm for carbon dioxide and at 2600 run for water vapor. In addition to the column abundance of water vapor, limited information on its vertical structure can also be retrieved depending on the signal available from aerosol scattering.
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- 2011
31. Assessment of a 2016 Mission Concept: The Search for Trace Gases in the Atmosphere of Mars
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Zurek, Richard W, Chicarro, Augustin, Allen, Mark A, Bertauz, Jean-Loup, Clancy, R. Todd, Daerden, Frank, Formisano, Vittorio, Garvin, James B, neukum, Gerhard, and Smith, Michael D
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Lunar And Planetary Science And Exploration - Abstract
The reported detection of methane in the atmosphere of Mars as well as its potentially large seasonal spatial variations challenge our understanding of both the sources and sinks of atmospheric trace gases. The presence of methane suggests ongoing exchange between the subsurface and the atmosphere of potentially biogenic trace gases, while the spatial and temporal variations cannot be accounted for with current knowledge of martian photochemistry. A Joint Instrument Definition Team (JIDT) was asked to assess concepts for a mission that might follow up on these discoveries within the framework of a series of joint missions being considered by ESA and NASA for possible future exploration of Mars. The following is based on the report of the JIDT to the space agencies (Zurek et al., 2009); a synopsis of the report was presented at the Workshop on Mars Methane held in Frascati, Italy, in November 2009. To summarize, the JIDT believed that a scientifically exciting and credible mission could be conducted within the evolving capabilities of the science/telecommunications orbiter being considered by ESA and NASA for possible launch in the 2016 opportunity for Mars.
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- 2011
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32. First Detection and Thermal Characterization of Terminator CO2 Ice Clouds With ExoMars/NOMAD.
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Liuzzi, Giuliano, Villanueva, Geronimo L., Trompet, Loïc, Crismani, Matteo M. J., Piccialli, Arianna, Aoki, Shohei, Lopez‐Valverde, Miguel Angel, Stolzenbach, Aurélien, Daerden, Frank, Neary, Lori, Smith, Michael D., Patel, Manish R., Lewis, Stephen R., Clancy, R. Todd, Thomas, Ian R., Ristic, Bojan, Bellucci, Giancarlo, Lopez‐Moreno, Jose‐Juan, and Vandaele, Ann Carine
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ICE clouds ,TRACE gases ,MARTIAN atmosphere ,ICE nuclei ,UPPER atmosphere ,FREEZING points - Abstract
We present observations of terminator CO2 ice clouds events in three groups: Equatorial dawn, Equatorial dusk (both between 20°S and 20°N) and Southern midlatitudes at dawn (45°S and 55°S east of Hellas Basin) with ESA ExoMars Trace Gas Orbiter's Nadir and Occultation for MArs Discovery instrument. CO2 ice abundance is retrieved simultaneously with water ice, dust, and particle sizes, and rotational temperature and CO2 column profiles in 16 of 26 cases. Small particles (<0.5 μm) prevail at dusk, while water ice likely provides most source nuclei at dawn. Clouds east of Hellas are found to be dominantly nucleated on surface‐lifted dust. CO2 ice is sometimes detected in unsaturated air together with dust nuclei at dawn, suggesting ongoing sublimation. Depending on latitude and local time, the interplay between particle precipitation and the lifetime of temperature minima (i.e., cold pockets) determines CO2 ice properties. Plain Language Summary: The upper atmosphere of Mars is characterized by the seasonal presence of CO2 ice clouds. Their properties have been long studied, as well as their formation mechanisms in relation to the thermal structure of the atmosphere and its variability. In this study, we present the first observations of these clouds at the terminator (dawn and dusk) by the NOMAD spectrometer onboard the Exomars Trace Gas Orbiter. CO2 ice is detected simultaneously with dust, water ice and the temperature profile. Our results agree with previous findings in terms of how clouds are spatially distributed and their temporal occurrence. However, we also explore the sources of condensation nuclei for CO2 ice particles, showing that water ice is a possible source at dawn near the Equator. We also identify surface‐lifted dust below the CO2 ice clouds observed east of Hellas Basin, suggesting that, at that location, dust could provide nuclei for CO2 ice. CO2 ice is also sometimes detected at temperatures higher than the CO2 freezing point, suggesting ongoing sublimation. In this work we explore for the first time the composition of CO2 ice clouds, which is critical to advance our understanding of how CO2 ice clouds form in the mesosphere at Mars. Key Points: Twenty Six mesospheric CO2 ice clouds were detected with NOMAD SO in Mars Year 35, simultaneously with water ice, dust, and CO2 saturation ratiosEquatorial CO2 clouds are observed at 50–80 km altitude at dusk, and 40–60 km at dawn, when water ice likely provides condensation nucleiSix CO2 ice clouds are found east of Hellas basin; their formation is likely sourced by surface‐lifted dust at 40–65 km [ABSTRACT FROM AUTHOR]
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- 2021
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33. Martian dust storm impact on atmospheric H2O and D/H observed by ExoMars Trace Gas Orbiter
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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., Svedhem, Håkan, Vago, Jorge L., Rodionov, Daniel, NOMAD Science Team, Alonso-Rodrigo, Gustavo, Bauduin, Sophie, Carrozzo, Giacomo, Crismani, Matteo, da Pieve, Fabiana, D'AVERSA, EMILIANO, Etiope, Giuseppe, Fussen, Didier, Geminale, Anna, Gkouvelis, Leo, Holmes, James, Hubert, Benoît, Ignatiev, Nicolay I., Kasaba, Yasumasa, Kass, David, Kleinböhl, Armin, LANCIANO, ORIETTA, Nakagawa, Hiromu, Novak, Robert E., Oliva, Fabrizio, Piccialli, Arianna, Renotte, Etienne, Ritter, Birgit, Schneider, Nick, SINDONI, Giuseppe, Thiemann, Ed, Vander Auwera, Jean, Wilquet, Valerie, WOLKENBERG, PAULINA MARIA, Yelle, Roger, ACS Science Team, Anufreychik, Konstantin, Arnold, Gabriele, Duxbury, Natalia, Fouchet, Thierry, GRASSI, Davide, Guerlet, Sandrine, Hartogh, Paul, Khatuntsev, Igor, Kokonkov, Nikita, Krasnopolsky, Vladimir, Kuzmin, Ruslan, Lacombe, Gaétan, Lellouch, Emmanuel, Määttänen, Anni, Marcq, Emmanuel, Martin-Torres, Javier, Medvedev, Alexander, Millour, Ehouarn, Moshkin, Boris, Quantin-Nataf, Cathy, Rodin, Alexander, Shematovich, Valery, Thomas, Nicolas, Trokhimovsky, Alexander, Vazquez, Luis, Vincendon, Matthieu, Young, Roland, Zasova, Ludmila, Zelenyi, Lev, Zorzano, Maria Paz, Parejo, J, Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique (BIRA-IASB), Space Research Institute of the Russian Academy of Sciences (IKI), Russian Academy of Sciences [Moscow] (RAS), Main Astronomical Observatory of NAS of Ukraine (MAO), National Academy of Sciences of Ukraine (NASU), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Istituto di Astrofisica e Planetologia Spaziali - INAF (IAPS), Istituto Nazionale di Astrofisica (INAF), Instituto Universitario de Microgravedad 'Ignacio Da Riva' (IDR), Universidad Politécnica de Madrid (UPM), Spectroscopie de l'atmosphère, Service de Chimie Quantique et Photophysique, Université libre de Bruxelles (ULB), Space Science Institute [Boulder] (SSI), Department of Geography [Winnipeg], University of Winnipeg, NASA Goddard Space Flight Center (GSFC), Laboratoire de Physique Atmosphérique et Planétaire (LPAP), Université de Liège, 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), Institute of Geophysics [Warsaw], Polska Akademia Nauk = Polish Academy of Sciences (PAN), Royal Observatory of Belgium [Brussels] (ROB), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Agenzia Spaziale Italiana (ASI), Graduate School of Information Sciences [Sendai], Tohoku University [Sendai], Advanced Mechanical and Optical Systems SA (AMOS), Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], School of Earth Sciences [Bristol], University of Bristol [Bristol], Centre for Research in Earth and Space Science [Toronto] (CRESS), York University [Toronto], Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, Department of Physics [Oxford], University of Oxford [Oxford], DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), 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), Lomonosov Moscow State University (MSU), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), 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)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, Institute for Astrophysics and Computational Sciences [Washington], Catholic University of America, Department of Computer Science, Electrical and Space Engineering [Luleå], Luleå University of Technology (LUT), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Moscow Institute of Physics and Technology [Moscow] (MIPT), Institute of Astronomy of the Russian Academy of Sciences (INASAN), University of Bern, Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centro de Astrobiologia [Madrid] (CAB), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), Consejo Superior de Investigaciones Científicas [Spain] (CSIC), Université Libre de Bruxelles [Bruxelles] (ULB), The Open University [Milton Keynes] (OU), Polska Akademia Nauk (PAN), Royal Observatory of Belgium [Brussels], IMPEC - LATMOS, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Universidad Complutense de Madrid [Madrid] (UCM), Consejo Superior de Investigaciones Científicas [Spain] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), Agence Spatiale Européenne = European Space Agency (ESA), University of Oxford, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Ministerio de Ciencia e Innovación (España), European Space Agency, Belgian Science Policy Office, European Commission, UK Space Agency, Agenzia Spaziale Italiana, Ministerio de Ciencia, Innovación y Universidades (España), Fonds de la Recherche Scientifique (Fédération Wallonie-Bruxelles), Roscosmos, Centre National de la Recherche Scientifique (France), and Russian Government
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Martian ,Ice cloud ,Multidisciplinary ,010504 meteorology & atmospheric sciences ,[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph] ,Storm ,Atmosphere of Mars ,Atmospheric sciences ,01 natural sciences ,Trace gas ,chemistry.chemical_compound ,chemistry ,13. Climate action ,Dust storm ,0103 physical sciences ,Environmental science ,Semiheavy water ,010303 astronomy & astrophysics ,Water vapor ,0105 earth and related environmental sciences ,Sciences exactes et naturelles - Abstract
A publisher correction to this article was published on 17 April 2019, Global dust storms on Mars are rare1,2 but can affect the Martian atmosphere for several months. They can cause changes in atmospheric dynamics and inflation of the atmosphere3, primarily owing to solar heating of the dust3. In turn, changes in atmospheric dynamics can affect the distribution of atmospheric water vapour, with potential implications for the atmospheric photochemistry and climate on Mars4. Recent observations of the water vapour abundance in the Martian atmosphere during dust storm conditions revealed a high-altitude increase in atmospheric water vapour that was more pronounced at high northern latitudes5,6, as well as a decrease in the water column at low latitudes7,8. Here we present concurrent, high-resolution measurements of dust, water and semiheavy water (HDO) at the onset of a global dust storm, obtained by the NOMAD and ACS instruments onboard the ExoMars Trace Gas Orbiter. We report the vertical distribution of the HDO/H2O ratio (D/H) from the planetary boundary layer up to an altitude of 80 kilometres. Our findings suggest that before the onset of the dust storm, HDO abundances were reduced to levels below detectability at altitudes above 40 kilometres. This decrease in HDO coincided with the presence of water-ice clouds. During the storm, an increase in the abundance of H2O and HDO was observed at altitudes between 40 and 80 kilometres. We propose that these increased abundances may be the result of warmer temperatures during the dust storm causing stronger atmospheric circulation and preventing ice cloud formation, which may confine water vapour to lower altitudes through gravitational fall and subsequent sublimation of ice crystals3. The observed changes in H2O and HDO abundance occurred within a few days during the development of the dust storm, suggesting a fast impact of dust storms on the Martian atmosphere. © 2019, The Author(s), under exclusive licence to Springer Nature Limited., This project acknowledges funding by the Belgian Science Policy Office (BELSPO), with 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 ESP2015-65064-C2-1-P and ESP2017-87143-R (MINECO/FEDER); by the UK Space Agency through grants ST/R005761/1, ST/P001262/1, ST/R001405/1, ST/S00145X/1, ST/R001367/1, ST/P001572/1 and ST/R001502/1; and the Italian Space Agency through grant 2018-2-HH.0. 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 Astrofisica de Andalucia (SEV-2017-0709). This work was supported by the Belgian Fonds de la Recherche Scientifique - FNRS under grant number 30442502 (ET_HOME). The ACS experiment is led by IKI, Space Research Institute in Moscow, assisted by LATMOS in France. The project acknowledges funding by Roscosmos and CNES. The science operations of ACS are funded by Roscosmos and ESA. IKI affiliates acknowledge funding under grant number 14.W03.31.0017 and contract number 0120.0 602993 (0028-2014-0004) of the Russian government.
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- 2019
34. Water Vapor Vertical Profiles on Mars in Dust Storms Observed by TGO/NOMAD
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Aoki, Shohei, Vandaele, Ann Carine, Daerden, Frank, Villanueva, Geronimo L., Liuzzi, Giuliano, Thomas, Ian R., Erwin, Justin T., Trompet, L., Robert, S., Neary, L., Viscardy, S., Ristic, Bojan, Patel, Manish R., Bellucci, Giancarlo, Bauduin, S., López-Moreno, José Juan, Alonso-Rodrigo, G., Fussen, D., Bolsée, D., Carrozzo, G., Clancy, R. Todd, Cloutis, E., Crismani, M., Da Pieve, F., D'Aversa, E., Kaminski, J., Depiesse, C., Garcia-Comas, M., Etiope, G., Fedorova, A.A., Funke, Bernd, Geminale, A., Gérard, Jean-Claude, Giuranna, M., Karatekin, O., Gkouvelis, L., González-Galindo, F., Holmes, J., Hubert, B., Mumma, M.J., Ignatiev, N.I., Kasaba, Y., Kass, D., Kleinböhl, A., Lanciano, O., Lefèvre, F., Lewis, S., López-Puertas, M., Schneider, Nicholas, Nakagawa, H., Hidalgo López, Ana, Mahieux, A., Mason, J., Mege, D., Neefs, E., Novak, R.E., Oliva, F., Sindoni, G., Piccialli, A., Renotte, E., Ritter, B., Willame, Y., Schmidt, F., Smith, M.D., Teanby, N.A., Thiemann, E., Trokhimovskiy, A., Auwera, J.V., Wolff, M.J., Clairquin, R., Whiteway, J., Wilquet, V., Wolkenberg, P., Yelle, R., del Moral Beatriz, A., Barzin, P., Beeckman, B., Cubas, J., BenMoussa, A., Berkenbosch, S., Orban, A., Biondi, D., Bonnewijn, S., Candini, G.P., Giordanengo, B., Gissot, S., Gomez, A., Hathi, B., Zafra, J.J., Leese, M., Maes, J., Pastor-Morales, M., Mazy, E., Mazzoli, A., Meseguer, J., Morales, R., Perez-grande, I., Queirolo, C., Ristic, R., Gomez, J.R., Saggin, B., Samain, V., Sanz Andres, A., Altieri, F., Sanz, R., Simar, J.-F., Thibert, T., the NOMAD team, López-Valverde, M. A., Hill, Brittany, Belgian Science Policy Office, European Space Agency, Ministerio de Ciencia e Innovación (España), European Commission, UK Space Agency, Agenzia Spaziale Italiana, Ministerio de Ciencia, Innovación y Universidades (España), Fonds de la Recherche Scientifique (Fédération Wallonie-Bruxelles), National Aeronautics and Space Administration (US), and Canadian Space Agency
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010504 meteorology & atmospheric sciences ,Storm ,Atmosphere of Mars ,Mars Exploration Program ,Atmospheric sciences ,01 natural sciences ,Trace gas ,Atmosphere ,Geophysics ,Space and Planetary Science ,Geochemistry and Petrology ,Dust storm ,Earth and Planetary Sciences (miscellaneous) ,Environmental science ,Hadley cell ,Water vapor ,0105 earth and related environmental sciences - Abstract
It has been suggested that dust storms efficiently transport water vapor from the near-surface to the middle atmosphere on Mars. Knowledge of the water vapor vertical profile during dust storms is important to understand water escape. During Martian Year 34, two dust storms occurred on Mars: a global dust storm (June to mid-September 2018) and a regional storm (January 2019). Here we present water vapor vertical profiles in the periods of the two dust storms (Ls = 162–260° and Ls = 298–345°) from the solar occultation measurements by Nadir and Occultation for Mars Discovery (NOMAD) onboard ExoMars Trace Gas Orbiter (TGO). We show a significant increase of water vapor abundance in the middle atmosphere (40–100 km) during the global dust storm. The water enhancement rapidly occurs following the onset of the storm (Ls~190°) and has a peak at the most active period (Ls~200°). Water vapor reaches very high altitudes (up to 100 km) with a volume mixing ratio of ~50 ppm. The water vapor abundance in the middle atmosphere shows high values consistently at 60°S-60°N at the growth phase of the dust storm (Ls = 195°–220°), and peaks at latitudes greater than 60°S at the decay phase (Ls = 220°–260°). This is explained by the seasonal change of meridional circulation: from equinoctial Hadley circulation (two cells) to the solstitial one (a single pole-to-pole cell). We also find a conspicuous increase of water vapor density in the middle atmosphere at the period of the regional dust storm (Ls = 322–327°), in particular at latitudes greater than 60°S. ©2019. American Geophysical Union. All Rights Reserved., S. A. is >Charge de Recherches> of the F.R.S.-FNRS. ExoMars is a space mission of the European Space Agency and Roscosmos. The NOMAD experiment is led by the Royal Belgian Institute for Space Aeronomy (IASBBIRA), 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, with the financial and contractual coordination by the European Space Agency Prodex Office (PEA 4000103401 and 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), as well as by UK Space Agency through grants ST/R005761/1, ST/P001262/1, ST/R001405/1, and ST/S00145X/1 and Italian Space Agency through grant 2018-2-HH.0. 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 Astrofisica de Andalucia (SEV-2017-0709). This work was supported by the Belgian Fonds de la Recherche Scientifique-FNRS under grant numbers 30442502 (ET_HOME) and T.0171.16 (CRAMIC) and Belgian Science Policy Office BrainBe SCOOP Project. U.S. investigators were supported by the National Aeronautics and Space Administration. Canadian investigators were supported by the Canadian Space Agency. The results retrieved from the NOMAD measurements used in this article are available on the BIRA-IASB data repository: http://repository.aeronomie.be/?doi= 10.18758/71021054 (Aoki et al., 2019).
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- 2019
35. No detection of methane on Mars from early ExoMars Trace Gas Orbiter observations
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Korablev, Oleg, Avandaele, Ann Carine, Montmessin, Franck, Fedorova, Anna A., Trokhimovskiy, Alexander, Forget, François, Lefèvre, Franck, Daerden, Frank, Thomas, Ian R., Trompet, Loïc, Erwin, Justin T., Kasaba, Yasumasa, Kass, David, Khatuntsev, Igor, Kleinböhl, Armin, Kokonkov, Nikita, Krasnopolsky, Vladimir, Kuzmin, Ruslan, Lacombe, Gaétan, LANCIANO, ORIETTA, Lellouch, Emmanuel, Oliva, Fabrizio, Lewis, Stephen, Luginin, Mikhail, Liuzzi, Giuliano, López-Puertas, Manuel, López-Valverde, Miguel, Määttänen, Anni, Mahieux, Arnaud, Marcq, Emmanuel, Martin-Torres, Javier, Maslov, Igor, Patsaev, Dmitry, Medvedev, Alexander, Millour, Ehouarn, Moshkin, Boris, Mumma, Michael J., Nakagawa, Hiromu, Novak, Robert E., Piccialli, Arianna, Quantin-Nataf, Cathy, Renotte, Etienne, Ritter, Birgit, Rodin, Alexander, Schmidt, Frédéric, Schneider, Nick, Shematovich, Valery, Aoki, Shohei, Smith, Michael D., Teanby, Nicholas A., Thiemann, Ed, Thomas, Nicolas, Vander Auwera, Jean, Vazquez, Luis, Villanueva, Geronimo, Vincendon, Matthieu, Whiteway, James, Wilquet, Valérie, Robert, Séverine, Wolff, Michael J., WOLKENBERG, PAULINA MARIA, Yelle, Roger, Young, Roland, Zasova, Ludmila, Zorzano, Maria Paz, 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., ACS Science Team, NOMAD Science Team, Alonso-Rodrigo, Gustavo, ALTIERI, FRANCESCA, Anufreychik, Konstantin, Arnold, Gabriele, Bauduin, Sophie, Bolsée, David, CARROZZO, FILIPPO GIACOMO, Clancy, R. Todd, CLOUTIS, EDWARD, Crismani, Matteo, da Pieve, Fabiana, D'AVERSA, EMILIANO, Duxbury, Natalia, Encrenaz, Therese, Fouchet, Thierry, Funke, Bernd, Fussen, Didier, Garcia-Comas, Maia, Gérard, Jean-Claude, GIURANNA, MARCO, Gkouvelis, Leo, Gonzalez-Galindo, Francisco, GRASSI, Davide, Guerlet, Sandrine, Hartogh, Paul, Holmes, James, Hubert, Benoît, Kaminski, Jacek, Karatekin, Ozgur, Space Research Institute of the Russian Academy of Sciences (IKI), Russian Academy of Sciences [Moscow] (RAS), Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique (BIRA-IASB), 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), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Department of Physics [Oxford], University of Oxford [Oxford], Main Astronomical Observatory of NAS of Ukraine (MAO), National Academy of Sciences of Ukraine (NASU), 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), Istituto di Astrofisica e Planetologia Spaziali - INAF (IAPS), Istituto Nazionale di Astrofisica (INAF), Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Roma (INGV), Istituto Nazionale di Geofisica e Vulcanologia, Faculty of Environmental Science and Engineering [Cluj-Napoca], Babes-Bolyai University [Cluj-Napoca] (UBB), European Space Research and Technology Centre (ESTEC), European Space Agency (ESA), Instituto Universitario de Microgravedad 'Ignacio Da Riva' (IDR), Universidad Politécnica de Madrid (UPM), DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Spectroscopie de l'atmosphère, Service de Chimie Quantique et Photophysique, Université libre de Bruxelles (ULB), Space Science Institute [Boulder] (SSI), Department of Geography [Winnipeg], University of Winnipeg, NASA Goddard Space Flight Center (GSFC), Lomonosov Moscow State University (MSU), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), 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)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Atmosphérique et Planétaire (LPAP), Université de Liège, Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, Institute of Geophysics [Warsaw], Polska Akademia Nauk = Polish Academy of Sciences (PAN), Royal Observatory of Belgium [Brussels] (ROB), Graduate School of Information Sciences [Sendai], Tohoku University [Sendai], Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Institute for Astrophysics and Computational Sciences [Washington], Catholic University of America, Agenzia Spaziale Italiana (ASI), Department of Computer Science, Electrical and Space Engineering [Luleå], Luleå University of Technology (LUT), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Advanced Mechanical and Optical Systems SA (AMOS), Moscow Institute of Physics and Technology [Moscow] (MIPT), Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Institute of Astronomy of the Russian Academy of Sciences (INASAN), School of Earth Sciences [Bristol], University of Bristol [Bristol], University of Bern, Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre for Research in Earth and Space Science [Toronto] (CRESS), York University [Toronto], Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, Belgian Science Policy Office, Ministerio de Ciencia e Innovación (España), European Commission, UK Space Agency, Centre National de la Recherche Scientifique (France), Fonds de la Recherche Scientifique (Fédération Wallonie-Bruxelles), Roscosmos, Russian Government, Agenzia Spaziale Italiana, European Space Agency, IMPEC - LATMOS, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris), The Open University [Milton Keynes] (OU), Consejo Superior de Investigaciones Científicas [Spain] (CSIC), Université Libre de Bruxelles [Bruxelles] (ULB), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Polska Akademia Nauk (PAN), Royal Observatory of Belgium [Brussels], Universidad Complutense de Madrid [Madrid] (UCM), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), University of Oxford, Agence Spatiale Européenne = European Space Agency (ESA), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), and Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES)
- Subjects
Martian ,Multidisciplinary ,[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph] ,010504 meteorology & atmospheric sciences ,Chemistry ,Atmosphere of Mars ,Mars Exploration Program ,01 natural sciences ,7. Clean energy ,Methane ,Trace gas ,law.invention ,Astrobiology ,Atmosphere ,Orbiter ,chemistry.chemical_compound ,13. Climate action ,law ,Atmospheric chemistry ,0103 physical sciences ,010303 astronomy & astrophysics ,Sciences exactes et naturelles ,0105 earth and related environmental sciences - Abstract
A publisher correction to this article was published on 17 April 2019, The detection of methane on Mars has been interpreted as indicating that geochemical or biotic activities could persist on Mars today1. A number of different measurements of methane show evidence of transient, locally elevated methane concentrations and seasonal variations in background methane concentrations2–5. These measurements, however, are difficult to reconcile with our current understanding of the chemistry and physics of the Martian atmosphere6,7, which—given methane’s lifetime of several centuries—predicts an even, well mixed distribution of methane1,6,8. Here we report highly sensitive measurements of the atmosphere of Mars in an attempt to detect methane, using the ACS and NOMAD instruments onboard the ESA-Roscosmos ExoMars Trace Gas Orbiter from April to August 2018. We did not detect any methane over a range of latitudes in both hemispheres, obtaining an upper limit for methane of about 0.05 parts per billion by volume, which is 10 to 100 times lower than previously reported positive detections2,4. We suggest that reconciliation between the present findings and the background methane concentrations found in the Gale crater4 would require an unknown process that can rapidly remove or sequester methane from the lower atmosphere before it spreads globally. © 2019, The Author(s), under exclusive licence to Springer Nature Limited., ExoMars is the space mission of ESA and Roscosmos. The ACS experiment is led by IKI, the Space Research Institute in Moscow, assisted by LATMOS in France. The project acknowledges funding by Roscosmos and CNES. The science operations of ACS are funded by Roscosmos and ESA. IKI affiliates acknowledge funding under grant number 14.W03.31.0017 and contract number 0120.0 602993 (0028-2014-0004) of the Russian government. The NOMAD experiment is led by the Royal Belgian Institute for Space Aeronomy (BIRA-IASB), assisted by co-PI teams from Spain (IAA-CSIC), Italy (INAF-IAPS), and the UK (Open University). This project acknowledges funding by the Belgian Science Policy Office (BELSPO), with the financial and contractual coordination of the ESA Prodex Office (PEA 4000103401 and PEA 4000121493), by Spanish MICINN through its Plan Nacional and by European funds under grants ESP2015-65064-C2-1-P and ESP2017-87143-R (MINECO/FEDER), as well as by the UK Space Agency through grants ST/R005761/1, ST/P001262/1, ST/R001405/1, ST/S00145X/1, ST/R001367/1, ST/P001572/1 and ST/R001502/1, and the Italian Space Agency through grant 2018-2-HH.0. This work was supported by the Belgian Fonds de la Recherche Scientifique-FNRS under grant number 30442502 (ET_HOME).
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- 2019
36. Compact Reconnaissance Imaging Spectrometer Observations of Water Vapor and Carbon Monoxide
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Smith, Michael D, Wolff, Michael J, Clancy, R. Todd, and Murchie, Scott L
- Subjects
Astronomy - Abstract
The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) onboard the Mars Reconnaissance Orbiter (MRO) spacecraft began taking observations in September 2006 and has now collected more than a full Martian year of data. Retrievals performed using the near-infrared spectra obtained by CRISM are used to characterize the seasonal and spatial variation of the column abundance of water vapor and the column-averaged mixing ratio of carbon monoxide. CRISM retrievals show nominal behavior in water vapor during northern hemisphere spring and summer with maximum abundance reaching 50 precipitable micrometers. Water vapor abundance during the southern hemisphere spring and summer appears significantly reduced compared to observations by other instruments taken during previous years. The CRISM retrievals show the seasonally and globally averaged carbon monoxide mixing ratio to be 700 ppm, but with strong seasonal variations at high latitudes. The summertime near-polar carbon monoxide mixing ratio falls to 200 ppm in the south and 400 ppm in the north as carbon dioxide sublimates from the seasonal polar ice caps and dilutes noncondensable species including carbon monoxide. At low latitudes, the carbon monoxide mixing ratio varies in response to the mean seasonal cycle of surface pressure.
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- 2009
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37. CRISM Observations of Water Vapor and Carbon Monoxide
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Smith, Michael D, Wolff, Michael J, and Clancy, R. Todd
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Astronomy - Abstract
Near-infrared spectra returned by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM, [1]) on-board the Mars Reconnaissance Orbiter (MRO) contain the clear spectral signature of several atmospheric gases including carbon dioxide (CO2), water vapor (H2O), and carbon monoxide (CO). Here we describe the seasonal and spatial mapping of water vapor and carbon dioxide for one full Martian year using CRISM spectra.
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- 2008
38. Microwave observations and modeling of a lunar eclipse
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Sandor, Brad J. and Clancy, R. Todd
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Eclipses, Lunar -- Models ,Moon -- Observations ,Astronomical photometry -- Models ,Astronomy ,Earth sciences - Abstract
Brightness temperature (TB) measurements of the moon obtained through microwave observations during the total lunar eclipse which occurred on Nov. 28-29, 1993 revealed that TB at the disk center fell by up to 25% from pre-eclipse levels. This behavior was adequately explained by a thermophysical regolith-only model in which the top 1-cm. regolith had a 1.4-gram-per-cubic-centimeter density and where density rises with depth.
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- 1995
39. A photochemical model of the Martian atmosphere
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Nair, Hari, Allen, Mark, Anbar, Ariel D., Yung, Yuk L., and Clancy, R. Todd
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Mars (Planet) -- Atmosphere ,Photochemical research -- Observations ,Astronomy ,Earth sciences - Abstract
A minimally restricted, one-dimensional photochemical model reveals the factors which determine the extent of CO, O3 and O2 abundance in the atmosphere of Mars. Gas phase chemistry and temperature-dependent molecules determine the abundance. The temperature-dependent CO2 absorption in the atmosphere increases the abundance of OH molecules, thereby reducing the CO abundance. The oxygen abundance depends on the oxygen escape flux in the Martian atmosphere.
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- 1994
40. Monitoring Mars with the Hubble Space Telescope: 1990-1991 observations
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James, Philip B., Clancy, R. Todd, Lee, Steven W., Martin, Leonard J., Singer, Robert B., Smith, Ed, Kahn, Ralph A., and Zurek, Richard W.
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Mars (Planet) -- Atmosphere ,Astronomy ,Earth sciences - Abstract
Hubble Space Telescopic images of Mars during 1990 and 1991 help examine atmospheric and polar phenomena. Calculated cloud opacity and column abundances exhibit 20% uncertainty. Ultraviolet limb brightening of Mars at low attitudes reveals a dust-free atmosphere for winter and spring. Dust activity is absent except near the receding north polar cap.
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- 1994
41. Mapping Mars water vapor with the Very Large Array
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Clancy, R. Todd, Grossman, Arie W., and Muhleman, Duane O.
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Water vapor, Atmospheric -- Observations ,Mars (Planet) -- Atmosphere ,Telescope -- Usage ,Astronomy ,Earth sciences - Abstract
Water vapor in the Martian atmosphere was mapped using a Very Large Array telescope operating at a wavelength of 1.35 cm. The results showed that global average water column was 3.0 +/- 0.8 pr micrometer, indicating that interannual variations in global water vapor occur. Maximum water vapor abundance was measured at 4.5 +/- 1.0 pr micrometer at equatorial latitudes. The polar water mixing ratio decreased at altitudes ranging from 15 to 50 km.
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- 1992
42. The Coupled Roles of Dust and Clouds in the Mars Climate
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Clancy, R. Todd
- Subjects
Lunar And Planetary Science And Exploration - Abstract
During the period October 1997 to September 1999 we obtained and analyzed over 100 millimeter-wave observations of Mars atmospheric CO line absorption for atmospheric temperature profiles. These measurements extend through one full Mars year (solar longitudes L(sub S) of 190 deg in 1997 to 180 deg in 1999) and coincide with atmospheric temperature profile and dust column measurements front the Thermal Emission Spectrometer (TES) experiment on board the Mars Global Surveyor (MGS) spacecraft. A comparison of Mars atmospheric temperatures retrieved by these distinct methods provides the first opportunity to place the long-term (1982-1999) millimeter retrievals of Mars atmospheric temperatures within the context of contemporaneous, spatially mapped spacecraft, observations. Profile comparisons of 0-30 km altitude atmospheric temperatures retrieved with the two techniques agree typically to within the 5 K calibration accuracy of the millimeter observations. At the 0.5 mbar pressure level (approximately 25 km altitude) the 30N/30S average for TES infrared temperatures and the disk-averaged millimeter temperatures are also well correlated in their seasonal and dust-storm-related variations over the 1997-1999 period. This period includes the Noachis Terra regional dust storm, which led to very abrupt heating (approximately 15 K at 0.5 mbar) of the global Mars atmosphere at L(sub S)=224 deg in 1997 [Christensen et al., 1998; Conrath et al., this issue; Smith et al., this issue]. Much colder (10-20 K) global atmospheric temperatures were observed during the 1997 versus 1977 perihelion periods (L(sub S)=200 deg-330 deg), consistent with the much (2 to 8 times) lower global dust loading of the atmosphere during the 1997 perihelion dust storm season versus the Viking period of the 1977a,b storms. The 1998-1999 Mars atmosphere revealed by both the millimeter and TES observations is also 10-15 K colder than presented by the Viking climatology during the aphelion season (L(sub S)=0 deg-180 deg, northern spring/summer) of Mars. We reassess the observational basis of the Viking dusty-warm climatology for this season to conclude that the global aphelion atmosphere of Mars is colder, less dusty, and cloudier than indicated by the established Viking climatology even for the Viking period. We also conclude that Mars atmospheric temperatures exhibit their most significant interannual variations during the perihelion dust storm season (10-20 K for L(sub S)=200 deg-340 deg) and during the post-aphelion northern summer season (5-10 K for L(sub S)=100 deg-200 deg).
- Published
- 2000
43. Mesospheric Observations and Modeling of the Zeeman Split 233.9 GHz O-18O-16 line
- Author
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Sandor, Brad J and Clancy, R. Todd
- Subjects
Geophysics - Abstract
Observations made from Kitt Peak, AZ, of the 233.9 GHz emission line of O-18O-16 in the upper stratosphere and lower mesosphere are reported. A good model fit to the line is obtained by incorporation of pressure and temperature broadening effects, as well as a Zeeman splitting algorithm that uses a standard geomagnetic field model and a paramagnetic Hamiltonian description of the molecular energy states. These observations are used, along with the well known O-18O-16 mixing ratio, to establish absolute calibration for observations of other chemical species from Kitt Peak. Repeated measurements show no change in this absolute calibration between observation dates. The wide magnetic splitting (+/-1.8 MHz) exhibited by this line with only six Zeeman components provides a unique test of middle atmosphere Zeeman effect model calculations, supporting the use Of 02 lines by microwave atmospheric sounders to measure pressure and temperature.
- Published
- 1997
- Full Text
- View/download PDF
44. Microwave Observations and Modeling of O2 (1-delta(sub g)) and O3 Diurnal Variation in the Mesosphere
- Author
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Sandor, Brad J, Clancy, R. Todd, Rusch, David W, Randall, Cora E, Eckman, Richard S, Siskind, David S, and Muhleman, Duane O
- Subjects
Geophysics - Abstract
The first microwave measurements of an electronically excited molecular species in the Earth's atmosphere are presented. Local thermodynamic equilibrium (LTE) rotational line emission from mesospheric O2(1-del(sub g)) was observed at a frequency of 255.01794 GHz (lambda is approx. 1.2 mm), employing the National Radio Astronomy Observatory (NRAO) millimeter facility at Kitt Peak, Arizona (32 N, 111 W). The pressure broadened line shapes of the O2(1-del(sub g)) spectra, which were obtained in January and April 1992 and in January and November 1993, are inverted to retrieve O2(1-del(sub g)) mixing profiles over the 50-70 km altitude region. The observed daytime abundances exceed ozone abundances in the lower mesosphere, which are separately retrieved with coincident O3 spectral line (249.7886 GHz) observations. The January and November 1993 observations are binned into 20-60 min time intervals to study O2(1-del(sub g)) diurnal behavior. Derived abundances of O2(1-del(sub g)) between 50 and 70 km for the four observation dates are 9%, 31%, 3%, and 26%, respectively, each +/- 10% higher than predicted, based on the simple photochemistry of lower mesospheric O2(1-del(sub g)). Modeled variation of [O2(1-del(sub g))] with time of day agrees with observed variation in that the observed difference between model and data abundances is constant throughout the daylight hours of each observation date. Model underprediction Of [02(lAg)] is consistent with similar model underprediction of mesospheric [O3]. A perturbation to the photochemical model that forces decreased ozone chemical loss brings brings both model [O3] and [O2(1-del(sub g))] into agreement with the observations. O2(1-del(sub g)) abundances derived from these 1.2 mm observations agree with [O2(1-del(sub g))] values derived from comparable SME observations of the 1.27 micrometers emission, with assumption of a 3880 sec O2(1-del(sub g)) radiative lifetime. The 6800 sec O2(1-del(sub g)) radiative lifetime proposed by Mlynczak and Nesbitt is ruled out by the similar comparison.
- Published
- 1997
- Full Text
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45. Cloud Ozone Dust Imager (CODI)
- Author
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Clancy, R. Todd, Dusenbery, Paul, Wolff, Michael, James, Phil, Allen, Mark, Goguen, Jay, Kahn, Ralph, Gladstone, Rany, and Murphy, Jim
- Subjects
Lunar And Planetary Exploration - Abstract
The Cloud Ozone Dust Imager (CODI) is proposed to investigate the current climatic balance of the Mars atmosphere, with particular emphasis on the important but poorly understood roles which dust and water ice aerosols play in this balance. The large atmospheric heating (20-50 K) resulting from global dust storms around Mars perihelion is well recognized. However, groundbased observations of Mars atmospheric temperatures, water vapor, and clouds since the Viking missions have identified a much colder, cloudier atmosphere around Mars aphelion that may prove as important as global dust storms in determining the interannual and long-term behavior of the Mars climate. The key climate issues CODI is designed to investigate are: 1) the degree to which non-linear interactions between atmospheric dust heating, water vapor saturation, and cloud nucleation influence the seasonal and interannual variability of the Mars atmosphere, and 2) whether the strong orbital forcing of atmospheric dust loading, temperatures and water vapor saturation determines the long-term balance of Mars water, as reflected in the north-south hemispheric asymmetries of atmospheric water vapor and polar water ice abundances. The CODI experiment will measure the daily, seasonal and (potentially) interannual variability of atmospheric dust and cloud opacities, and the key physical properties of these aerosols which determine their role in the climate cycles of Mars. CODI is a small (1.2 kg), fixed pointing camera, in which four wide-angle (+/- 70 deg) lenses illuminate fixed filters and CCD arrays. Simultaneous sky/surface imaging of Mars is obtained at an angular resolution of 0.28 deg/pixel for wavelengths of 255, 336, 502, and 673 nm (similar to Hubble Space Telescope filters). These wavelengths serve to measure atmospheric ozone (255 and 336 nm), discriminate ice and dust aerosols (336 and 673 nm), and construct color images (336, 502, and 673 nm). The CODI images are detected on four 512 x 512 pixel arrays, as partitioned on two 1024 x 1024 CCD's operated in frame transfer mode. The center of the CODI field-of-view is canted 40 deg from the zenith direction to obtain sky brightness measurements and a 20 deg surface field-of-view. Daily image observations will be conducted when the Sun is greater than or equal to 5 deg outside the edge of the CODI field-of-view, and twilight and nighttime imaging will obtained on a weekly basis. The 673 nm channel includes a polarizer wheel to obtain sky/surface polarimetry. A dust cover protects the entire lens assemblies of all four CODI channels. This opaque dust cover, which is normally opened for CODI imaging, includes a small fixed mirror and transparent window positioned above the 673 nm lens, to redirect the 673 nm field-of-view to the surface for descent imaging. Fixed pointing, internal data buffering, low operating power (2-4 W for less than or equal to 30 seconds), selective data transmission, and simple operational characteristics of the CODI experiment place minimum resource and operational demands on the Mars Surveyor 1998 lander. The CODI science goals are optimized for, but not restricted to, a low-latitude landing site (20 deg S-30 deg N). The primary CODI measurement objectives are the opacities, wave forms, particle properties (size, shape, and alignment), and heights of clouds; the opacities, particle properties, and vertical distribution of dust; and the opacity and vertical distribution of ozone. The variability of cloud, ozone, and dust opacities will be determined on diurnal, daily, and seasonal timescales. Wind velocities will be determined from cloud motions and wave characteristics; and the temporal variability of atmospheric water vapor, with limited altitude information, will be inferred from the CODI ozone observations. Secondary measurement objectives include limited descent imaging capability, surface uv-visible photometry and polarimetry, photochemistry, and meteorite infall rates.
- Published
- 1995
46. Temperature minima in the average thermal structure of the middle mesosphere (70 - 80 km) from analysis of 40- to 92-km SME global temperature profiles
- Author
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Clancy, R. Todd, Rusch, David W, and Callan, Michael T
- Subjects
Meteorology And Climatology - Abstract
Global temperatures have been derived for the upper stratosphere and mesosphere from analysis of Solar Mesosphere Explorer (SME) limb radiance profiles. The SME temperature represent fixed local time observations at 1400 - 1500 LT, with partial zonal coverage of 3 - 5 longitudes per day over the 1982-1986 period. These new SME temperatures are compared to the COSPAR International Ionosphere Reference Atmosphere 86 (CIRA 86) climatology (Fleming et al., 1990) as well as stratospheric and mesospheric sounder (SAMS); Barnett and Corney, 1984), National Meteorological Center (NMC); (Gelman et al., 1986), and individual lidar and rocket observations. Significant areas of disagreement between the SME and CIRA 86 mesospheric temperatures are 10 K warmer SME temperatures at altitudes above 80 km. The 1981-1982 SAMS temperatures are in much closer agreement with the SME temperatures between 40 and 75 km. Although much of the SME-CIRA 86 disagreement probably stems from the poor vertical resolution of the observations comprising the CIRA 86 modelm, some portion of the differences may reflect 5- to 10-year temporal variations in mesospheric temperatures. The CIRA 86 climatology is based on 1973-1978 measurements. Relatively large (1 K/yr) 5- to 10-year trends in temperatures as functions of longitude, latitude, and altitude have been observed for both the upper stratosphere (Clancy and Rusch, 1989a) and mesosphere (Clancy and Rusch, 1989b; Hauchecorne et al., 1991). The SME temperatures also exhibit enhanced amplitudes for the semiannual oscillation (SAO) of upper mesospheric temperatures at low latitudes, which are not evident in the CIRA 86 climatology. The so-called mesospheric `temperature inversions' at wintertime midlatitudes, which have been observed by ground-based lidar (Hauschecorne et al., 1987) and rocket in situ measurements (Schmidlin, 1976), are shown to be a climatological aspect of the mesosphere, based on the SME observations.
- Published
- 1994
- Full Text
- View/download PDF
47. An analysis of Solar Mesospheric Explorer temperatures for the upper stratosphere and mesosphere
- Author
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Clancy, R. Todd and Rusch, David W
- Subjects
Solar Physics - Abstract
We proposed to analyze Solar Mesosphere Explorer (SME) limb profiles of Rayleigh scattered solar flux at wavelengths of 304, 313, and 443 nm to retrieve atmospheric temperature profiles over the 40-65 km altitude region. These temperatures can be combined with the previous analysis of SME 296 nm limb radiances to construct a monthly average climatology of atmospheric temperatures over the 40-90 km, upper stratosphere-mesosphere region, with approximately 4 km vertical resolution. We proposed to investigate the detailed nature of the global temperature structure of this poorly measured region, based on these 1982-1986 SME temperatures. The average vertical structure of temperatures between the stratopause and mesopause has never been determined globally with vertical resolution sufficient to retrieve even scale-height structures. Hence, the SME temperatures provided a unique opportunity to study the detailed thermal structure of the mesosphere, in advance of Upper Atmosphere Research Satellite (UARS) measurements and the Thermosphere Ionosphere Mesosphere Energy and Dynamics (TIMED) mission.
- Published
- 1993
48. Observations of Mars using Hubble Space Telescope
- Author
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James, Philip B, Clancy, R. Todd, Lee, Steven W, Kahn, Ralph, Zurek, Richard, Martin, Leonard, and Singer, Robert
- Subjects
Lunar And Planetary Exploration - Abstract
The lack of a continuous record of Martian meteorology or of volatile cycles on Mars for extended periods of several Martian years seriously hinders efforts to understand the physics of the Martian atmosphere and surface system. The spacecraft observations are limited to only a few isolated time periods, and the Earth based record is limited by the relatively short periods surrounding oppositions when telescopic observations can yield useful data. To remedy this situation, the authors have embarked on a three year program of Mars observations using the Hubble Space Telescope (HST). Several scientific investigations are being carried out using the images, including: a study of the albedo variations; unit mapping of spectral reflectances; determination of optical depths due to aerosols and condensates; a study of the properties of condensate clouds and hoods; comparison of surface and atmospheric features; observation of size and shape of the polar caps; and investigation of surface atmospheric phenomena.
- Published
- 1992
49. Martian atmospheric chemistry during the time of low water abundance
- Author
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Nair, Hari, Allen, Mark, Yung, Yuk L, and Clancy, R. Todd
- Subjects
Lunar And Planetary Exploration - Abstract
The importance of odd hydrogen (or HO(x)) radicals in the catalytic recombination of carbon monoxide and oxygen in the Martian atmosphere is a well known fact. The inclusion of recent chemical kinetics data, specifically temperature-dependent CO2 absorption cross sections, into our one dimensional photochemical model shows that HO(x) is too efficient in this regard. The absorption cross sections of CO2 are smaller than previously assumed; this leads to a reduction in the photolysis rate of CO2 while the photolysis rate of H2O has increased. As a consequence the predicted mixing ratio of CO in our models is substantially less than the observed value of 6.5(10)(exp -4). Simultaneous measurements of water, ozone, and carbon monoxide were obtained in the Martian atmosphere in early Dec. 1990 (L(sub s) for Mars was 344 deg.).
- Published
- 1992
50. Planetary atmospheres: Microwave spectroscopic studies of planetary atmospheres
- Author
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Clancy, R. Todd
- Subjects
Lunar And Planetary Exploration - Abstract
Ground-based spectroscopic observations of isotopes of CO in the atmospheres of Mars, Venus, and Titan have been collected over the 1982-1990 period. These observations have been analyzed to obtain information on the photochemistry, dynamics, and thermal profiles of these planetary atmospheres. In the cases of the mesosphere (80-100 km altitude) of Venus and the lower atmosphere (0-70 km altitude) of Mars, the primary conclusion of this research is that significant interannual variations in the global thermal and compositional structures of these atmospheres occur over 10 year periods. The Titan studies have focussed on pinning down the true atmospheric CO abundance. A more detailed summary of the results for each of these planetary atmospheres is provided.
- Published
- 1991
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