Science.gov

Sample records for dynamic atmosphere composition

  1. Street Canyon Atmospheric Composition: Coupling Dynamics and Chemistry

    NASA Astrophysics Data System (ADS)

    Bright, V.; Bloss, W. J.; Cai, X.

    2010-12-01

    Atmospheric composition within the urban environment, particularly within street canyons (formed by a road running between two rows of buildings), has a direct effect on the air quality of an environment in which a large majority of people live and work. The composition of air within a street canyon is determined by the composition of background air mixed in from above, advection of air into and out of the canyon, vehicle exhaust and other emissions from within the street, together with the mixing and chemical processing of pollutants within the canyon. This occurs on a timescale of a few seconds to minutes and as a result, within-canyon atmospheric processes can have a significant effect on atmospheric composition on such timescales. This paper outlines a modelling study of street canyon atmospheric composition, integrating the combined effects of emissions, dynamics and chemistry. This work builds upon an existing dynamical model of canyon atmospheric motion (Large Eddy Simulation (LES) model) by adding a detailed chemical reaction scheme. Previous studies have considered basic NOx-O3 cycles with only a small number of chemical reactions included. Initially, a zero-dimensional box model was used to develop and assess the accuracy of a suitable reduced chemical scheme to be included within the LES. The reduced chemical scheme, based upon a subset of the Master Chemical Mechanism (MCM), includes 51 chemical species and 136 reactions. Vehicle emissions taken from the UK National Atmospheric Emissions Inventory (NAEI) were subsequently added to the box model. These elements were then combined with the canyon dynamics simulated by the Large Eddy Simulation (LES) model. Results demonstrate that the enhanced model is a suitable tool to be used to further investigate the combined effects of mixing and chemical processing upon air quality within the street canyon. Subsequently, a number of key questions relating to urban atmospheric composition are addressed using the

  2. Atmospheric composition

    NASA Technical Reports Server (NTRS)

    Daniels, G. E.

    1973-01-01

    The earth's atmosphere is made up of a number of gases in different relative amounts. Near sea level and up to about 90 km, the amount of these atmospheric gases in clean, relatively dry air is practically constant. Four of these gases, nitrogen, oxygen, argon, and carbon dioxide, make up 99.99 percent by volume of the atmosphere. Two gases, ozone and water vapor, change in relative amounts, but the total amount of these two is very small compared to the amount of the other gases. The atmospheric composition shown in a table can be considered valid up to 90 km geometric altitude. Above 90 km, mainly because of molecular dissociation and diffusive separation, the composition changes.

  3. Composition/Structure/Dynamics of comet and planetary satellite atmospheres

    NASA Technical Reports Server (NTRS)

    Combi, Michael R. (Principal Investigator)

    1995-01-01

    This research program addresses two cases of tenuous planetary atmospheres: comets and Io. The comet atmospheric research seeks to analyze a set of spatial profiles of CN in comet Halley taken in a 7.4-day period in April 1986; to apply a new dust coma model to various observations; and to analyze observations of the inner hydrogen coma, which can be optically thick to the resonance scattering of Lyman-alpha radiation, with the newly developed approach that combines a spherical radiative transfer model with our Monte Carlo H coma model. The Io research seeks to understand the atmospheric escape from Io with a hybrid-kinetic model for neutral gases and plasma given methods and algorithms developed for the study of neutral gas cometary atmospheres and the earth's polar wind and plasmasphere. Progress is reported on cometary Hydrogen Lyman-alpha studies; time-series analysis of cometary spatial profiles; model analysis of the dust comae of comets; and a global kinetic atmospheric model of Io.

  4. Effects of Bulk Composition on the Atmospheric Dynamics on Close-in Exoplanets

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Showman, A. P.

    2014-04-01

    Depending on the metallicity of the protoplanetary disk, the details of gas accretion during planetary formation, and atmospheric loss during planetary evolution, the atmospheres of exoplanets could exhibit a variety of bulk compositions (e.g., Moses et al., 2013). Examples include hydrogen-dominated atmospheres like Jupiter, more metal-rich (but still hydrogen-dominated) atmospheres like Neptune, evaporated atmospheres dominated by helium in analogy to helium white dwarfs, or of course carbon dioxide, water vapour, nitrogen, and other heavy molecules as exhibited by terrestrial planets in the solar system. Despite differing opacities that will impact the radiative energy deposition (e.g., Lewis et al., 2010; Kataria et al., 2014), differing bulk compositions also differ in molecular weight and specific heat. The latter two fundamental parameters might have crucial effects on various aspects of atmospheric structure and dynamics. For example, a lower specific heat from molecules such as carbon dioxide implies a steeper dry adiabatic temperature gradient; this implies that, for a given vertical temperature profile, atmospheres with differing molecular weights exhibit different Brunt-Väisälä frequencies and therefore gravity wave speeds. Molecular weight also influences the scale height of the atmosphere, which could range (for typical exoplanet gravities) from ten km for high-molecularweight compositions to hundreds of km for hydrogen-dominated cases. A lower molecular weight or a lower specific heat would likely cause a larger deformation radius in which the atmospheric flow is more significantly influenced by the gravity and buoyancy effects instead of the rotation effects. In this study we use a three-dimensional general circulation model (GCM) to simulate generic exoplanets with different compositions, emphasizing close-in, synchronously rotating super Earths whose atmospheric composition is the most uncertain and which will be the focus of characterization

  5. Effects of Bulk Composition on the Atmospheric Dynamics on Close-in Exoplanets

    NASA Astrophysics Data System (ADS)

    Zhang, Xi; Showman, Adam P.

    2017-02-01

    Super Earths and mini Neptunes likely have a wide range of atmospheric compositions, ranging from low molecular mass atmospheres of H2 to higher molecular atmospheres of water, CO2, N2, or other species. Here we systematically investigate the effects of atmospheric bulk compositions on temperature and wind distributions for tidally locked sub-Jupiter-sized planets, using an idealized 3D general circulation model (GCM). The bulk composition effects are characterized in the framework of two independent variables: molecular weight and molar heat capacity. The effect of molecular weight dominates. As the molecular weight increases, the atmosphere tends to have a larger day–night temperature contrast, a smaller eastward phase shift in the thermal phase curve, and a smaller zonal wind speed. The width of the equatorial super-rotating jet also becomes narrower, and the “jet core” region, where the zonal-mean jet speed maximizes, moves to a greater pressure level. The zonal-mean zonal wind is more prone to exhibit a latitudinally alternating pattern in a higher molecular weight atmosphere. We also present analytical theories that quantitatively explain the above trends and shed light on the underlying dynamical mechanisms. Those trends might be used to indirectly determine the atmospheric compositions on tidally locked sub-Jupiter-sized planets. The effects of the molar heat capacity are generally small. But if the vertical temperature profile is close to adiabatic, molar heat capacity will play a significant role in controlling the transition from a divergent flow in the upper atmosphere to a jet-dominated flow in the lower atmosphere.

  6. Effects of bulk composition on the atmospheric dynamics on close-in exoplanets

    NASA Astrophysics Data System (ADS)

    Zhang, Xi; Showman, Adam P.

    2014-11-01

    Depending on the metallicity of the protoplanetary disk, the details of gas accretion during planetary formation, and atmospheric loss during planetary evolution, the atmospheres of exoplanets could exhibit a variety of bulk compositions (e.g., Moses et al., 2013). Examples include hydrogen-dominated atmospheres like Jupiter, more metal-rich (but still hydrogen-dominated) atmospheres like Neptune, evaporated atmospheres dominated by helium in analogy to helium white dwarfs, or of course carbon dioxide, water vapor, nitrogen, and other heavy molecules as exhibited by terrestrial planets in the solar system. Despite differing opacities that will impact the radiative energy deposition (e.g., Lewis et al., 2010), differing bulk compositions also differ in molecular weight and heat capacity. The latter two fundamental parameters might have crucial effects on various aspects of atmospheric structure and dynamics. Molecular weight may influence the scale height, Brunt-Väisälä frequencies and therefore gravity wave speeds in the atmosphere. A lower molecular weight or a lower heat capacity would likely to result a larger deformation radius in which the atmospheric flow is more significantly influenced by the gravity and buoyancy effects instead of the rotation effects. We use a three-dimensional general circulation model to simulate generic sub-Jupiter exoplanets, especially those close to their host stars-known as “hot Neptunes” or close-in “super-Earths”. We found that the atmosphere with lower molecular mass favors zonal jets and equatorial superrotation, and that with lower heat capacity favors day-to-night divergent flow. Our results suggest that super Earths and hotNeptunes will exhibit large meteorological diversity due to bulk composition effects. Since atmospheres with fast zonal jets tends to have smaller day-night temperature difference due to larger circulation efficiency and larger hot spot phase shift than that with day-to-night divergent flows

  7. Effects of Bulk Composition on the Atmospheric Dynamics on Close-in Exoplanets

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Showman, A. P.

    2015-12-01

    Depending on the metallicity of the protoplanetary disk, the details of gas accretion during planetary formation, and atmospheric loss during planetary evolution, the atmospheres of sub-Jupiter-sized planets could exhibit a variety of bulk compositions. Examples include hydrogen-dominated atmospheres like Jupiter, more metal-rich atmospheres like Neptune, evaporated atmospheres dominated by helium, or of course carbon dioxide, water vapor, nitrogen, and other heavy molecules as exhibited by terrestrial planets in the solar system. Here we systematically investigate the effects of atmospheric bulk compositions on temperature and wind distributions for tidally locked sub-Jupiter-sized planets using an idealized three-dimensional general circulation model (GCM). Composition—in particular, the molecular mass and specific heat—affect the sound speed, gravity wave speeds, atmospheric scale height, and Rossby deformation radius, and therefore in principle can exert significant controls on the atmospheric circulation, including the day-night temperature difference and other observables. We performed numerous simulations exploring a wide range of molecular masses and molar specific heats. The effect of molecular weight dominates. We found that a higher-molecular-weight atmosphere tends to have a larger day-night temperature contrast, a smaller eastward phase shift in the thermal light curve, and a narrower equatorial super-rotating jet that occurs in a deeper atmosphere. The zonal-mean zonal wind is smaller and more prone to exhibit a latitudinally alternating pattern in a higher-molecular-weight atmosphere. If the vertical temperature profile is close to adiabatic, molar specific heat will play a significant role in controlling the transition from a divergent flow in the upper atmosphere to a jet-dominated flow in the lower atmosphere. We are also working on analytical theories to explain aspects of the simulations relevant for possible observables on tidally locked

  8. Effects of Bulk Composition on the Atmospheric Dynamics on Close-in Exoplanets

    NASA Astrophysics Data System (ADS)

    Zhang, Xi; Showman, Adam P.

    2015-12-01

    Depending on the metallicity of the protoplanetary disk and processes such as gas accretion during planetary formation and atmospheric loss during planetary evolution, the atmospheres of sub-Jupiter-sized planets could exhibit a variety of bulk compositions. Examples include hydrogen-dominated atmospheres like Jupiter, more metal-rich atmospheres like Neptune, carbon dioxide, water vapor, nitrogen, and other heavy molecules as exhibited by terrestrial planets in the solar system. In this study we systematically investigate the effects of atmospheric bulk compositions on temperature and wind distributions for tidally locked sub-Jupiter-sized planets such as super-Earths and mini-Neptunes, using an idealized three-dimensional general circulation model (GCM). Composition—in particular, the molecular mass and specific heat—affect the sound speed, gravity wave speeds, atmospheric scale height, and Rossby deformation radius, and therefore in principle can exert significant controls on the atmospheric circulation, including the day-night temperature difference and other observables.We performed numerous simulations exploring a wide range of molecular masses and molar specific heats. The effect of molecular weight dominates. We found that a higher-molecular-weight atmosphere tends to have a larger day-night temperature contrast, a smaller eastward phase shift in the thermal light curve, and a narrower equatorial super-rotating jet that occurs in a deeper atmosphere. The zonal-mean zonal wind is smaller and more prone to exhibit a latitudinally alternating pattern in a higher-molecular-weight atmosphere. If the vertical temperature profile is close to adiabatic, molar specific heat will play a significant role in controlling the transition from a divergent flow in the upper atmosphere to a jet-dominated flow in the lower atmosphere.In order to understand the systematic behavior and capture the underlying physics, we present analytical theories to explain aspects of the

  9. Lunar atmospheric composition experiment

    NASA Technical Reports Server (NTRS)

    Hoffman, J. H.

    1975-01-01

    Apollo 17 carried a miniature mass spectrometer, called the Lunar Atmospheric Composition Experiment (LACE), to the moon as part of the Apollo Lunar Surface Experiments Package (ALSEP) to study the composition and variations in the lunar atmosphere. The instrument was successfully deployed in the Taurus-Littrow Valley with its entrance aperture oriented upward to intercept and measure the downward flux of gases at the lunar surface. During the ten lunations that the LACE operated, it produced a large base of data on the lunar atmosphere, mainly collected at night time. It was found that thermal escape is the most rapid loss mechanism for hydrogen and helium. For heavier gases, photoionization followed by acceleration through the solar wind electric field accounted for most of the loss. The dominant gases on the moosn were argon and helium, and models formed for their distribution are described in detail. It is concluded that most of the helium in the lunar atmosphere is of solar wind origin, and that there also exist very small amounts of methane, ammonia, and carbon dioxide.

  10. Linking activity, composition and seasonal dynamics of atmospheric methane oxidizers in a meadow soil

    PubMed Central

    Shrestha, Pravin Malla; Kammann, Claudia; Lenhart, Katharina; Dam, Bomba; Liesack, Werner

    2012-01-01

    Microbial oxidation is the only biological sink for atmospheric methane. We assessed seasonal changes in atmospheric methane oxidation and the underlying methanotrophic communities in grassland near Giessen (Germany), along a soil moisture gradient. Soil samples were taken from the surface layer (0–10 cm) of three sites in August 2007, November 2007, February 2008 and May 2008. The sites showed seasonal differences in hydrological parameters. Net uptake rates varied seasonally between 0 and 70 μg CH4 m−2 h−1. Greatest uptake rates coincided with lowest soil moisture in spring and summer. Over all sites and seasons, the methanotrophic communities were dominated by uncultivated methanotrophs. These formed a monophyletic cluster defined by the RA14, MHP and JR1 clades, referred to as upland soil cluster alphaproteobacteria (USCα)-like group. The copy numbers of pmoA genes ranged between 3.8 × 105–1.9 × 106 copies g−1 of soil. Temperature was positively correlated with CH4 uptake rates (P<0.001), but had no effect on methanotrophic population dynamics. The soil moisture was negatively correlated with CH4 uptake rates (P<0.001), but showed a positive correlation with changes in USCα-like diversity (P<0.001) and pmoA gene abundance (P<0.05). These were greatest at low net CH4 uptake rates during winter times and coincided with an overall increase in bacterial 16S rRNA gene abundances (P<0.05). Taken together, soil moisture had a significant but opposed effect on CH4 uptake rates and methanotrophic population dynamics, the latter being increasingly stimulated by soil moisture contents >50 vol% and primarily related to members of the MHP clade. PMID:22189499

  11. Study of atmospheric dynamics

    NASA Technical Reports Server (NTRS)

    Mcnider, Richard T.; Christy, John R.; Cox, Gregory N.

    1993-01-01

    In order to better understand the dynamics of the global atmosphere, a data set of precision temperature measurements was developed using the NASA built Microwave Sounding Unit. Modeling research was carried out to validate global model outputs using various satellite data. Idealized flows in a rotating annulus were studied and applied to the general circulation of the atmosphere. Dynamic stratospheric ozone fluctuations were investigated. An extensive bibliography and several reprints are appended.

  12. Studies for the 3-Dimensional Structure, Composition, and Dynamic of Io's Atmosphere

    NASA Technical Reports Server (NTRS)

    Smyth, William H.

    2001-01-01

    Research work is discussed for the following: (1) the exploration of new H and Cl chemistry in Io's atmosphere using the already developed two-dimensional multi-species hydrodynamic model of Wong and Smyth; and (2) for the development of a new three-dimensional multi-species hydrodynamic model for Io's atmosphere.

  13. Dynamics of planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Ingersoll, Andrew P.

    1989-01-01

    The overall goal is to illuminate the mechanisms that control weather and climate on the Earth and other planets. Each planet presents its own puzzling behavior - the stability of jets and vortices in Jupiter's otherwise turbulent atmosphere, the superrotation of the Venus atmosphere, the interplay of dust, polar volatiles, and climate change in Mars, the supersonic meteorology of Io, and the counterintuitive equator-to-pole temperature gradients on the outer planets. The data sets are generally those obtained from spacecraft - cloud-tracked winds, radiometrically inferred temperatures, and the results of in situ observations where appropriate. The approach includes both data analysis and modeling, ranging from analytic modeling to time-dependent numerical modeling of atmospheric dynamics. The latter approach involves the use of supercomputers such as the San Diego Cray. Progress is generally made when a model with a small number of free parameters either fits a data set that has a large number of independent observations or applies to several planets at once.

  14. The Atmospheric Infrared Sounder (AIRS) on the NASA Aqua Spacecraft: A General Remote Sensing Tool for Understanding Atmospheric Structure, Dynamics and Composition

    NASA Technical Reports Server (NTRS)

    Pagano, Thomas S.; Chahine, Moustafa T.; Fetzer, Eric J.

    2010-01-01

    The Atmospheric Infrared Sounder (AIRS) on the EOS Aqua Spacecraft was launched on May 4, 2002. Early in the mission, the AIRS instrument demonstrated its value to the weather forecasting community with better than 6 hours of improvement on the 5 day forecast. Now with over eight years of consistent and stable data from AIRS, scientists are able to examine processes governing weather and climate and look at seasonal and interannual trends from the AIRSdata with high statistical confidence. Naturally, long-term climate trends require a longer data set, but indications are that the Aqua spacecraft and the AIRS instrument should last beyond 2018. This paper briefly describes the AIRS data products and presents some of the most significant findings involving the use of AIRS data in the areas of weather forecast improvement, climate processes and model validation, cloud and polar processes, and atmospheric composition (chemistry and dust).

  15. Finding Atmospheric Composition (AC) Metadata

    NASA Technical Reports Server (NTRS)

    Strub, Richard F..; Falke, Stefan; Fiakowski, Ed; Kempler, Steve; Lynnes, Chris; Goussev, Oleg

    2015-01-01

    The Atmospheric Composition Portal (ACP) is an aggregator and curator of information related to remotely sensed atmospheric composition data and analysis. It uses existing tools and technologies and, where needed, enhances those capabilities to provide interoperable access, tools, and contextual guidance for scientists and value-adding organizations using remotely sensed atmospheric composition data. The initial focus is on Essential Climate Variables identified by the Global Climate Observing System CH4, CO, CO2, NO2, O3, SO2 and aerosols. This poster addresses our efforts in building the ACP Data Table, an interface to help discover and understand remotely sensed data that are related to atmospheric composition science and applications. We harvested GCMD, CWIC, GEOSS metadata catalogs using machine to machine technologies - OpenSearch, Web Services. We also manually investigated the plethora of CEOS data providers portals and other catalogs where that data might be aggregated. This poster is our experience of the excellence, variety, and challenges we encountered.Conclusions:1.The significant benefits that the major catalogs provide are their machine to machine tools like OpenSearch and Web Services rather than any GUI usability improvements due to the large amount of data in their catalog.2.There is a trend at the large catalogs towards simulating small data provider portals through advanced services. 3.Populating metadata catalogs using ISO19115 is too complex for users to do in a consistent way, difficult to parse visually or with XML libraries, and too complex for Java XML binders like CASTOR.4.The ability to search for Ids first and then for data (GCMD and ECHO) is better for machine to machine operations rather than the timeouts experienced when returning the entire metadata entry at once. 5.Metadata harvest and export activities between the major catalogs has led to a significant amount of duplication. (This is currently being addressed) 6.Most (if not all

  16. Atmospheric and Oceanic Fluid Dynamics

    NASA Astrophysics Data System (ADS)

    Vallis, Geoffrey K.

    2006-11-01

    Fluid dynamics is fundamental to our understanding of the atmosphere and oceans. Although many of the same principles of fluid dynamics apply to both the atmosphere and oceans, textbooks tend to concentrate on the atmosphere, the ocean, or the theory of geophysical fluid dynamics (GFD). This textbook provides a comprehensive unified treatment of atmospheric and oceanic fluid dynamics. The book introduces the fundamentals of geophysical fluid dynamics, including rotation and stratification, vorticity and potential vorticity, and scaling and approximations. It discusses baroclinic and barotropic instabilities, wave-mean flow interactions and turbulence, and the general circulation of the atmosphere and ocean. Student problems and exercises are included at the end of each chapter. Atmospheric and Oceanic Fluid Dynamics: Fundamentals and Large-Scale Circulation will be an invaluable graduate textbook on advanced courses in GFD, meteorology, atmospheric science and oceanography, and an excellent review volume for researchers. Additional resources are available at www.cambridge.org/9780521849692. Includes end of chapter review questions to aid understanding Unified and comprehensive treatment of both atmospheric and oceanic fluid dynamics Covers many modern topics and provides up to date knowledge

  17. The Structure and Composition of Io's Atmosphere

    NASA Astrophysics Data System (ADS)

    Smyth, W. H.; Marconi, M. L.

    2011-12-01

    Io's atmosphere is thought to be generated principally by sublimation on the dayside and by multiple volcanoes scattered throughout its surface and more concentrated near the equator. While SO2 seems to be the principle product of these sources, many other chemical species are placed into the atmosphere by these sources, including substantial amounts of SO and S2 as well as smaller but observationally significant amounts of Na bearing molecules. These species in turn interact strongly with the torus plasma generating additional species such as O2, S, O, and Na. The strong interaction of the torus plasma with the neutral atmosphere not only exerts a profound effect on the composition of Io's atmosphere but also strongly affects the dynamics and thermodynamics of Io's atmosphere, particularly at higher altitudes. In addition, as Io orbits Jupiter, the change in location of the sublimation region and the eclipse of Io as it passes through Jupiter's shadow result in substantial variation in the atmosphere. A complex time-dependent three-dimensional atmosphere with strong spatial compositional variation is created. Here we extend the two-dimensional multispecies Navier-Stokes model of Smyth and Wong (2004) to three-dimensions, include two volcanic sources similar to Pele and Loki, and include the effect of Io's movement around Jupiter on sublimation. The effects of the torus plasma are also included as in Smyth and Wong. We will present the overall composition and structure of the atmosphere, O to S ratios in the upper atmosphere, and discuss a potential issue with the O2 abundance. Smyth, W.H. and M.C. Wong, Icarus 171, 171-182, 2004.

  18. Dynamics of Triton's atmosphere

    NASA Technical Reports Server (NTRS)

    Ingersoll, Andrew P.

    1990-01-01

    It is argued here that the facts about Triton's atmosphere discovered by the recent Voyager encounter can be explained if Triton, like Mars, has a global, well-structured atmosphere in equilibrium with surface frosts. The subliming frost cap produces a polar anticyclone at low altitudes, with northeastward winds of about 5 m/s within the Ekman boundary layer. The temperature contrast between the cold frost-covered pole and the warm unforested equator produces westward winds at high altitudes.

  19. Atmospheric Composition Change: Climate-Chemistry Interactions

    NASA Technical Reports Server (NTRS)

    Isaksen, I.S.A.; Granier, C.; Myhre, G.; Bernsten, T. K.; Dalsoren, S. B.; Gauss, S.; Klimont, Z.; Benestad, R.; Bousquet, P.; Collins, W.; Cox, T.; Eyring, V.; Fowler, D.; Fuzzi, S.; Jockel, P.; Laj, P.; Lohmann, U.; Maione, M.; Monks, T.; Prevot, A. S. H.; Raes, F.; Richter, A.; Rognerud, B.; Schulz, M.; Shindell, D.; Stevenson, D. S.; Storelvmo, T.; Wang, W.-C.; vanWeele, M.; Wild, M.; Wuebbles, D.

    2011-01-01

    Chemically active climate compounds are either primary compounds such as methane (CH4), removed by oxidation in the atmosphere, or secondary compounds such as ozone (O3), sulfate and organic aerosols, formed and removed in the atmosphere. Man-induced climate-chemistry interaction is a two-way process: Emissions of pollutants change the atmospheric composition contributing to climate change through the aforementioned climate components, and climate change, through changes in temperature, dynamics, the hydrological cycle, atmospheric stability, and biosphere-atmosphere interactions, affects the atmospheric composition and oxidation processes in the troposphere. Here we present progress in our understanding of processes of importance for climate-chemistry interactions, and their contributions to changes in atmospheric composition and climate forcing. A key factor is the oxidation potential involving compounds such as O3 and the hydroxyl radical (OH). Reported studies represent both current and future changes. Reported results include new estimates of radiative forcing based on extensive model studies of chemically active climate compounds such as O3, and of particles inducing both direct and indirect effects. Through EU projects such as ACCENT, QUANTIFY, and the AEROCOM project, extensive studies on regional and sector-wise differences in the impact on atmospheric distribution are performed. Studies have shown that land-based emissions have a different effect on climate than ship and aircraft emissions, and different measures are needed to reduce the climate impact. Several areas where climate change can affect the tropospheric oxidation process and the chemical composition are identified. This can take place through enhanced stratospheric-tropospheric exchange of ozone, more frequent periods with stable conditions favouring pollution build up over industrial areas, enhanced temperature-induced biogenic emissions, methane releases from permafrost thawing, and enhanced

  20. Lidar investigations of atmospheric dynamics

    NASA Astrophysics Data System (ADS)

    Philbrick, C. Russell; Hallen, Hans D.

    2015-09-01

    Ground based lidar techniques using Raleigh and Raman scattering, differential absorption (DIAL), and supercontinuum sources are capable of providing unique signatures to study dynamical processes in the lower atmosphere. The most useful profile signatures of dynamics in the lower atmosphere are available in profiles of time sequences of water vapor and aerosol optical extinction obtained with Raman and DIAL lidars. Water vapor profiles are used to study the scales and motions of daytime convection cells, residual layer bursts into the planetary boundary layer (PBL), variations in height of the PBL layer, cloud formation and dissipation, scale sizes of gravity waves, turbulent eddies, as well as to study the seldom observed phenomena of Brunt-Väisälä oscillations and undular bore waves. Aerosol optical extinction profiles from Raman lidar provide another tracer of dynamics and motion using sequential profiles atmospheric aerosol extinction, where the aerosol distribution is controlled by dynamic, thermodynamic, and photochemical processes. Raman lidar profiles of temperature describe the stability of the lower atmosphere and measure structure features. Rayleigh lidar can provide backscatter profiles of aerosols in the troposphere, and temperature profiles in the stratosphere and mesosphere, where large gravity waves, stratospheric clouds, and noctilucent clouds are observed. Examples of several dynamical features are selected to illustrate interesting processes observed with Raman lidar. Lidar experiments add to our understanding of physical processes that modify atmospheric structure, initiate turbulence and waves, and describe the relationships between energy sources, atmospheric stability parameters, and the observed dynamics.

  1. Uranus atmospheric dynamics and circulation

    NASA Technical Reports Server (NTRS)

    Allison, Michael; Beebe, Reta F.; Conrath, Barney J.; Hinson, David P.; Ingersoll, Andrew P.

    1991-01-01

    The observations, models, and theories relevant to the atmospheric dynamics and meteorology of Uranus are discussed. The available models for the large-scale heat transport and atmospheric dynamics as well as diagnostic interpretations of the Voyager data are reviewed. Some pertinent ideas and questions regarding the global circulation balance are considered, partly in comparison with other planetary atmospheres. The available data indicate atmospheric rotation at midlatitudes nearly 200 m/s faster than that of the planetary magnetic field. Analysis of the dynamical deformation of the shape and size of isobaric surfaces measured by the Voyager radio-occultation experiment suggests a subrotating equator at comparable altitudes. Infrared temperature retrievals above the cloud deck indicate a smaller equator-to-pole contrast than expected for purely radiative-convective equilibrium, but show local variations implying a latitudinally correlated decrease with altitude in the cloud-tracked wind.

  2. Atmospheric composition change: Ecosystems-Atmosphere interactions

    NASA Astrophysics Data System (ADS)

    Fowler, D.; Pilegaard, K.; Sutton, M. A.; Ambus, P.; Raivonen, M.; Duyzer, J.; Simpson, D.; Fagerli, H.; Fuzzi, S.; Schjoerring, J. K.; Granier, C.; Neftel, A.; Isaksen, I. S. A.; Laj, P.; Maione, M.; Monks, P. S.; Burkhardt, J.; Daemmgen, U.; Neirynck, J.; Personne, E.; Wichink-Kruit, R.; Butterbach-Bahl, K.; Flechard, C.; Tuovinen, J. P.; Coyle, M.; Gerosa, G.; Loubet, B.; Altimir, N.; Gruenhage, L.; Ammann, C.; Cieslik, S.; Paoletti, E.; Mikkelsen, T. N.; Ro-Poulsen, H.; Cellier, P.; Cape, J. N.; Horváth, L.; Loreto, F.; Niinemets, Ü.; Palmer, P. I.; Rinne, J.; Misztal, P.; Nemitz, E.; Nilsson, D.; Pryor, S.; Gallagher, M. W.; Vesala, T.; Skiba, U.; Brüggemann, N.; Zechmeister-Boltenstern, S.; Williams, J.; O'Dowd, C.; Facchini, M. C.; de Leeuw, G.; Flossman, A.; Chaumerliac, N.; Erisman, J. W.

    Ecosystems and the atmosphere: This review describes the state of understanding the processes involved in the exchange of trace gases and aerosols between the earth's surface and the atmosphere. The gases covered include NO, NO 2, HONO, HNO 3, NH 3, SO 2, DMS, Biogenic VOC, O 3, CH 4, N 2O and particles in the size range 1 nm-10 μm including organic and inorganic chemical species. The main focus of the review is on the exchange between terrestrial ecosystems, both managed and natural and the atmosphere, although some new developments in ocean-atmosphere exchange are included. The material presented is biased towards the last decade, but includes earlier work, where more recent developments are limited or absent. New methodologies and instrumentation have enabled, if not driven technical advances in measurement. These developments have advanced the process understanding and upscaling of fluxes, especially for particles, VOC and NH 3. Examples of these applications include mass spectrometric methods, such as Aerosol Mass Spectrometry (AMS) adapted for field measurement of atmosphere-surface fluxes using micrometeorological methods for chemically resolved aerosols. Also briefly described are some advances in theory and techniques in micrometeorology. For some of the compounds there have been paradigm shifts in approach and application of both techniques and assessment. These include flux measurements over marine surfaces and urban areas using micrometeorological methods and the up-scaling of flux measurements using aircraft and satellite remote sensing. The application of a flux-based approach in assessment of O 3 effects on vegetation at regional scales is an important policy linked development secured through improved quantification of fluxes. The coupling of monitoring, modelling and intensive flux measurement at a continental scale within the NitroEurope network represents a quantum development in the application of research teams to address the underpinning

  3. Atmospheric composition - Influence of biology

    NASA Technical Reports Server (NTRS)

    Mcelroy, M. B.

    1983-01-01

    The variability of atmospheric constituents influenced by biological organisms over various time scales is examined, together with the human contribution to atmospheric sulfur. The biogeochemistry of nitrogen is discussed, with an emphasis on N2O, NO, and microbially mediated reactions in soil and water. Carbon species are bound up mainly in sediments and the deep ocean, but human activities involving combustion may cause a doubling of the atmospheric levels of CO2 in the near future, which could produce a general low-level atmospheric warming. Longer term measurements are required to assess the effects of CH4 augmentation in the atmosphere through fuel combustion. Coal burning effectively doubles the amount of SO2 produced by natural sources, and reduces the pH of rainwater, thus posing hazards to fish, plankton, and mollusc life.

  4. Photodissociation dynamics and atmospheric chemistry

    NASA Astrophysics Data System (ADS)

    Wayne, R. P.

    1993-07-01

    The paper uses data from the literature to explore photodissociation dynamics of molecules possessing three, four, and five atoms, as represented by O3 and CO2, NH3 and C2H2, and CH4, respectively. The results yield many details, even in regard to the disposal of energy into rotation, which have applications to atmospheric problems. For instance, experiments probing the translational energies of the O and the vibrational and rotational distributions in the CO suggest that a spin-forbidden channel operates as it does in ozone photolysis. The data for both O3 and CO2 suggest a relationship between the structure of the parent molecule and the dynamics of dissociation.

  5. Titan's Atmospheric Dynamics and Meteorology

    NASA Technical Reports Server (NTRS)

    Flasar, F. M.; Baines, K. H.; Bird, M. K.; Tokano, T.; West, R. A.

    2008-01-01

    Titan, after Venus, is the second example of an atmosphere with a global cyclostrophic circulation in the solar system, but a circulation that has a strong seasonal modulation in the middle atmosphere. Direct measurement of Titan's winds, particularly observations tracking the Huygens probe at 10degS, indicate that the zonal winds are generally in the sense of the satellites rotation. They become cyclostrophic approx. 35 km above the surface and generally increase with altitude, with the exception of a sharp minimum centered near 75 km, where the wind velocity decreases to nearly zero. Zonal winds derived from the temperature field retrieved from Cassini measurements, using the thermal wind equation, indicate a strong winter circumpolar vortex, with maximum winds at mid northern latitudes of 190 ms-' near 300 km. Above this level, the vortex decays. Curiously, the zonal winds and temperatures are symmetric about a pole that is offset from the surface pole by approx.4 degrees. The cause of this is not well understood, but it may reflect the response of a cyclostrophic circulation to the offset between the equator, where the distance to the rotation axis is greatest, and the solar equator. The mean meridional circulation can be inferred from the temperature field and the meridional distribution of organic molecules and condensates and hazes. Both the warm temperatures in the north polar region near 400 km and the enhanced concentration of several organic molecules suggests subsidence there during winter and early spring. Stratospheric condensates are localized at high northern latitudes, with a sharp cut-off near 50degN. Titan's winter polar vortex appears to share many of the same characteristics of winter vortices on Earth-the ozone holes. Global mapping of temperatures, winds, and composition in he troposphere, by contrast, is incomplete. The few suitable discrete clouds that have bee found for tracking indicate smaller velocities than aloft, consistent with the

  6. An assessment model for atmospheric composition

    NASA Technical Reports Server (NTRS)

    Prather, Michael J. (Editor)

    1988-01-01

    Predicting future perturbations to global air quality and climate requires, as a prerequisite, prognostic models for the composition of the Earth's atmosphere. Such assessment models are needed to evaluate the impact on our environment of different social choices that affect emissions of the photochemically and radiatively important trace gases. Our presentation here of a prototype assessment model is intended to encourage public scientific discussions of the necessary components of the model and their interactions, with the recognition that models similar to this will likely be used by the Environmental Protection Agency and other regulatory agencies in order to assess the effect of changes in atmospheric composition on climate over the next century.

  7. Composition and chemistry of Saturn's atmosphere

    NASA Technical Reports Server (NTRS)

    Prinn, R. G.; Larson, H. P.; Caldwell, J. J.; Gautier, D.

    1984-01-01

    A comprehensive discussion and review is presented of the chemistry and composition of Saturn as determined by earth-based, earth-orbital, and Voyager 1 and 2 spectroscopic observations. The observations imply that there are important differences between the actual composition of Saturn's atmosphere and that predicted for a homogeneous solar-composition planet. The H2, He, Ch4, NH3, and PH3 volume mixing ratios differ from the expected solar composition ratios, implying that during its formation Saturn accreted a significant amount of ice and rock. The depletion of He in the visible atmosphere suggests that this element has preferentially differentiated toward the center of the planet. The D to H ratio is similar to that on Jupiter and has important cosmological implications. Volume mixing ratios for C2H6 and C2H2 are consistent with the theoretically expected photochemical sources for these gases.

  8. Atmospheric Data Package for the Composite Analysis

    SciTech Connect

    Napier, Bruce A.; Ramsdell, James V.

    2005-09-01

    The purpose of this data package is to summarize our conceptual understanding of atmospheric transport and deposition, describe how this understanding will be simplified for numerical simulation as part of the Composite Analysis (i.e., implementation model), and finally to provide the input parameters needed for the simulations.

  9. Dynamic of the atmospheric boundary layer from the isotopic composition of surface water vapor at the Maïdo Observatory (La Réunion, Indian Ocean)

    NASA Astrophysics Data System (ADS)

    Guilpart, Etienne; Vimeux, Francoise; Metzger, Jean-Marc; Evan, Stephanie; Brioude, Jerome; Cattani, Olivier

    2016-04-01

    Projections of tropical and subtropical precipitation strongly differ from one climate model to another, both in sign and in amplitude. This is the case for example in some parts of the West Indian Ocean. The causes of those uncertainties are numerous and a better understanding of humid processes in the tropical atmosphere is needed. We propose to address this burning question by using water stables isotopes. We have been measuring the isotopic composition of surface water vapor at the atmospheric Observatory of Maïdo located at La Reunion Island (21°S, 55°E, 2200m a.s.l) since November 2014. Our results exhibit a strong diurnal cycle all over the year (except during cyclonic activity), with almost constant isotopic values during the day (around -13.5±0.6‰ for oxygen 18 from November 2014 to November 2015) and variable and very depleted isotopic values during the night (down to -35‰ for oxygen 18 over the same period) associated with low humidity levels. We will show in this presentation that the diurnal isotopic variations are associated to a strong air masses mixing. During the day, the isotopic composition of the vapor is typical of marine boundary layer (BL) moisture transported from the close Ocean and lifted up to the Maïdo station. During the night, the depleted values and the low humidity could trace free troposphere moisture, which is consistent with previous studies suggesting that the Maïdo Observatory is above the BL during the night. We will explore the influence of the daily BL development on our observations, using a set of atmospheric vertical profiles done on site in May 2015 during the BIOMAIDO campaign. At last, we will discuss the most isotopic depleted values recorded in our observations during the night as a possible consequence of regional strong subsidences.

  10. Oxygen isotopic composition of carbon dioxide in the middle atmosphere.

    PubMed

    Liang, Mao-Chang; Blake, Geoffrey A; Lewis, Brenton R; Yung, Yuk L

    2007-01-02

    The isotopic composition of long-lived trace molecules provides a window into atmospheric transport and chemistry. Carbon dioxide is a particularly powerful tracer, because its abundance remains >100 parts per million by volume (ppmv) in the mesosphere. Here, we successfully reproduce the isotopic composition of CO(2) in the middle atmosphere, which has not been previously reported. The mass-independent fractionation of oxygen in CO(2) can be satisfactorily explained by the exchange reaction with O((1)D). In the stratosphere, the major source of O((1)D) is O(3) photolysis. Higher in the mesosphere, we discover that the photolysis of (16)O(17)O and (16)O(18)O by solar Lyman-alpha radiation yields O((1)D) 10-100 times more enriched in (17)O and (18)O than that from ozone photodissociation at lower altitudes. This latter source of heavy O((1)D) has not been considered in atmospheric simulations, yet it may potentially affect the "anomalous" oxygen signature in tropospheric CO(2) that should reflect the gross carbon fluxes between the atmosphere and terrestrial biosphere. Additional laboratory and atmospheric measurements are therefore proposed to test our model and validate the use of CO(2) isotopic fractionation as a tracer of atmospheric chemical and dynamical processes.

  11. New Discoveries Resulted from Lidar Investigation of Middle and Upper Atmosphere Temperature, Composition, Chemistry and Dynamics at McMurdo, Antarctica

    NASA Astrophysics Data System (ADS)

    Chu, X.; Yu, Z.; Fong, W.; Chen, C.; Huang, W.; Lu, X.; Gardner, C. S.; McDonald, A.; Fuller-Rowell, T. J.; Vadas, S.

    2013-12-01

    discoveries may have opened the new door to observing the neutral thermosphere with ground-based instruments. Extreme Fe events in summer were observed and understood as the interesting interactions among the meteoric metal atoms, sub-visible ice particles and energetic particles during aurora precipitation. Furthermore, the McMurdo middle and upper atmosphere is found to be very dynamical, especially in winter when inertia-gravity waves and eastward propagating planetary waves are predominant in the mesosphere and lower thermosphere and in the stratosphere, respectively. Despite small amplitudes below 100 km, the diurnal and semidiurnal tidal amplitudes exhibit fast growth from 100 to 110 km depending on the geomagnetic activities. These observations pose great challenges to our understanding of the Earth's upper atmosphere but also provide excellent opportunities to exploring how the electrodynamics and neutral dynamics work together at this high southern latitude to produce many intriguing geophysical phenomena.

  12. Atmospheric dynamics of tidally synchronized extrasolar planets.

    PubMed

    Cho, James Y-K

    2008-12-13

    Tidally synchronized planets present a new opportunity for enriching our understanding of atmospheric dynamics on planets. Subject to an unusual forcing arrangement (steady irradiation on the same side of the planet throughout its orbit), the dynamics on these planets may be unlike that on any of the Solar System planets. Characterizing the flow pattern and temperature distribution on the extrasolar planets is necessary for reliable interpretation of data currently being collected, as well as for guiding future observations. In this paper, several fundamental concepts from atmospheric dynamics, likely to be central for characterization, are discussed. Theoretical issues that need to be addressed in the near future are also highlighted.

  13. Dynamics of the Venus atmosphere

    NASA Technical Reports Server (NTRS)

    Ingersoll, A. P.

    1992-01-01

    The superrotation of the Venus atmosphere is a major unanswered problem in planetary science. At cloud-top levels (65-70 km altitude) the atmosphere rotates with a five-day period, corresponding to an equatorial wind speed of 90 m/s. Angular velocity is roughly constant on spherical shells, and decreases linearly with altitude to zero at the surface. The direction of rotation is the same as that of the solid planet, which is retrograde--opposite to the direction of orbital motion, but the 5-day period is short compared to the 243-day spin period of the solid planet or to the mean solar day, which is 117 Earth-days at the surface. The problem with the superrotation is that shearing stresses tend to transfer angular momentum downward, and would slow the atmosphere until it is spinning with the solid planet. Some organized circulation pattern is counteracting the tendency, but the pattern has not been identified. A simple Hadley-type circulation cannot do it because such a circulation is zonally symmetric and Hide's Theorem states that in an axisymmetric circulation an extremum in angular momentum per unit mass M can exist only at the surface. Venus violates the last condition, having a maximum of retrograde M on the equator at 70-80 km altitude. This leaves waves and eddies to maintain the superrotation but the length scales and forcing mechanisms for these motions need to be specified. Possible forcing mechanisms associated with waves, eddies and tides are discussed.

  14. Composition, Chemistry, and Climate of the Atmosphere. 2: Mean properties of the atmosphere

    NASA Technical Reports Server (NTRS)

    Singh, Hanwant B. (Editor); Salstein, David A.

    1994-01-01

    The atmosphere can be defined as the relatively thin gaseous envelope surrounding the entire planet Earth. It possesses a number of properties related to its physical state and chemical composition, and it undergoes a variety of internal processes and external interactions that can either maintain or alter these properties. Whereas descriptions of the atmosphere's chemical properties form much of the remaining chapters of this book, the present chapter will highlight the atmosphere's gases, and these define its temperature structure. In contrast, the larger-scale motions comprise the winds, the global organization of which is often referred to as the general circulation. The framework of the dynamical and thermodynamical laws, including the three principles of conversation of mass, momentum, and energy, are fundamental in describing both the internal processes of the atmosphere and its external interactions. The atmosphere is not a closed system, because it exchanges all three of these internally conservative quantities across the atmosphere's boundary below and receives input from regions outside it. Thus surface fluxes of moisture, momentum, and heat occur to and from the underlying ocean and land. The atmosphere exchanges very little mass and momentum with space, though it absorbs directly a portion of the solar radiational energy received from above.

  15. Atmospheric dynamics of the outer planets

    NASA Technical Reports Server (NTRS)

    Ingersoll, Andrew P.

    1990-01-01

    Despite major differences in the solar and internal energy inputs, the atmospheres of the four Jovian planets all exhibit latitudinal banding and high-speed jet streams. Neptune and Saturn are the windiest planets, Jupiter is the most active, and Uranus is a tipped-over version of the others. Large oval storm systems exhibit complicated time-dependent behavior that can be simulated in numerical models and laboratory experiments. The largest storm system, the Great Red Spot of Jupiter, has survived for more than 300 years in a chaotic shear zone where smaller structures appear and dissipate every few days. Future space missions will add to the understanding of small-scale processes, chemical composition, and vertical structure. Theoretical hypotheses about the interiors provide input for fluid dynamical models that reproduce many observed features of the winds, temperatures, and cloud patterns. In one set of models the winds are confined to the thin layer where clouds form. In other models, the winds extend deep into the planetary fluid interiors. Hypotheses will be tested further as observations and theories become more exact and detailed comparisons are made.

  16. Structure and dynamics of Saturn's atmosphere

    NASA Technical Reports Server (NTRS)

    Ingersoll, A. P.; Beebe, R. F.; Conrath, B. J.; Hunt, G. E.

    1984-01-01

    The large-scale structure and dynamics of Saturn's atmosphere, as revealed in the visible markings, wind patterns, and horizontal variation of temperature, are discussed. The large-scale thermal structure is addressed, including the mean vertical structure and the seasons and jets of the horizontal temperature structure. Earth-based and Voyager wind observations are used to discuss the internal rate of rotation, the zonal wind profile, the eddies, and the eddy transport. Dynamic models of the atmospheric circulation are reviewed, discussing the depth of the zonal flow, upwelling and downwelling, deep convection, eddy-mean flow interactions, long-lived ovals, and the zonal velocity profile.

  17. Titan's Atmospheric Composition from Observations by the Cassini Infrared Spectrometer

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; LeClair, A.; Flasar, F. M.; Kunde, V. G.; Conrath, B. J.; Coustenis, A.; Jennings, D. J.; Nixon, C. A.; Brasunas, J.; Achterberg, R. K.

    2006-01-01

    The Composite Infrared Spectrometer (CIRS) aboard the Cassini spacecraft has been making observations during the fly-bys of Titan since the Saturn-Orbit-Insertion in July 2004. The observations provide infrared them1 emission spectra of Titan s atmosphere in three spectral channels covering the 10/cm to 1400/cm spectral region, with variable spectral resolutions of 0.53/cm and 2.8/cm. The uniquely observed spectra exhibit rotational and vibrational-rotational spectral lines of the molecular constituents of Titan s atmosphere that may be analyzed to retrieve information about the composition, thermal structure, and physical and dynamical processes in the remotely sensed atmosphere. We present an analysis of Titan's infrared spectra observed during July 2004 (TO), December 2004 (Tb) and February 2005 (T3), for retrieval of the stratospheric thermal structure, distribution of the hydrocarbons, nitriles, and oxygen bearing constituents, such as C2H2, C2H4, C2H6, C3H8, HCN, HC3N, CO, and CO2 . Preliminary results on the distribution and opacity of haze in Titan s atmosphere are discussed.

  18. The Stable Isotopic Composition of Atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Yakir, D.

    2003-12-01

    When a bean leaf was sealed in a closed chamber under a lamp (Rooney, 1988), in two hours the atmospheric CO2 in the microcosm reached an isotopic steady state with a 13C abundance astonishingly similar to the global mean value of atmospheric CO2 at that time (-7.5‰ in the δ13C notation introduced below). Almost concurrently, another research group sealed a suspension of asparagus cells in a different type of microcosm in which within about two hours the atmospheric O2 reached an isotopic steady state with 18O enrichment relative to water in the microcosm that was, too, remarkably similar to the global-scale offset between atmospheric O2 and mean ocean water (21‰ versus 23.5‰ in the δ18O notation introduced below; Guy et al., 1987). These classic experiments capture some of the foundations underlying the isotopic composition of atmospheric CO2 and O2. First, in both cases the biological system rapidly imposed a unique isotopic value on the microcosms' atmosphere via their massive photosynthetic and respiratory exchange of CO2 and O2. Second, in both cases the biological system acted on materials with isotopic signals previously formed by the global carbon and hydrological cycles. That is, the bean leaf introduced its previously formed organic matter (the source of the CO2 respired into microcosm's atmosphere), and the asparagus cells were introduced complete with local tap water (from which photosynthesis released molecular oxygen). Therefore, while the isotopic composition of the biological system used was slave to long-term processes, intense metabolic processes centered on few specific enzymes (Yakir, 2002) dictated the short-term atmospheric composition.In a similar vein, on geological timescales of millions of years, the atmosphere and its isotopic composition are integral parts of essentially a single dynamic ocean-atmosphere-biosphere system. This dynamic system exchanges material, such as carbon and oxygen, with the sediments and the lithosphere via

  19. Atmospheric Composition and Chemistry Discoveries from Space

    NASA Astrophysics Data System (ADS)

    Douglass, A. R.; Stolarski, R. S.

    2005-12-01

    Satellite observations have given scientists a global perspective on the photochemical and dynamical processes that control the atmospheric evolution of constituents like ozone. The satellites and their instruments are often designed to address specific questions and sometimes vastly exceed their developer's expectations. The Total Ozone Mapping Spectrometer (TOMS) was designed to simply map the variability of the ozone column due to atmospheric waves. The instruments on the Upper Atmosphere Research Satellite (UARS) were designed to measure upper stratospheric ozone and quantities important to ozone including solar flux, winds and constituents that contribute to ozone destruction. The scientific payoff from UARS and TOMS vastly exceeded these modest goals. Total ozone measurements from TOMS revealed the extent and variability of the Antarctic ozone hole. UARS instruments showed the spatial structures of the conversion of chlorine species from reservoirs to radicals and back to reservoirs during the seasonal development and disappearance of the ozone hole. UARS investigators discovered previously unknown features of the atmospheric circulation. For example, long-lived tracer measurements showed unmixed descent of mesospheric air into the polar lower stratosphere as the winter vortex was formed. Observations of water vapor in the tropical stratosphere showed that air parcels carry the memory of the tropical tropopause temperature for years as they ascend through the stratosphere (the tropical "tape recorder"). The persistence of this signature places constraints on mass flux into the stratosphere and the mixing between tropical and middle latitudes. Satellite data have yielded unexpected bonuses. Improvements in the understanding of the TOMS retrieval algorithm allowed for the removal of drifts in instrument performance to produce a stable climate-quality data set for trend analysis. Apparent noise in the retrievals was eventually understood to be due to aerosols

  20. CIDGA - Coupling of Interior Dynamic models with Global Atmosphere models

    NASA Astrophysics Data System (ADS)

    Noack, Lena; Plesa, Ana-Catalina; Breuer, Doris

    2010-05-01

    Atmosphere temperatures and in particular the surface temperatures mostly depend on the solar heat flux and the atmospheric composition. The latter can be influenced by interior processes of the planet, i.e. volcanism that releases greenhouse gases such as H2O, CO2 and methane into the atmosphere and plate tectonics through which atmospheric CO2 is recycled via carbonates into the mantle. An increasing concentration of greenhouse gases in the atmosphere results in an increase of the surface temperature. Changes in the surface temperature on the other hand may influence the cooling behaviour of the planet and hence influence its volcanic activity [Phillips et al., 2001]. This feedback relation between mantle convection and atmosphere is not very well understood, since until now mostly either the interior dynamic of a planet or its atmosphere was investigated separately. 2D or 3D mantle convection models to the authors' knowledge haven't been coupled to the atmosphere so far. We have used the 3D spherical simulation code GAIA [Hüttig et al., 2008] including partial melt production and coupled it with the atmosphere module CIDGA using a gray greenhouse model for varying H2O concentrations. This way, not only the influence of mantle dynamics on the atmosphere can be investigated, but also the recoupling effect, that the surface temperature has on the mantle dynamics. So far, we consider one-plate planets without crustal and thus volatile recycling. Phillips et al. [2001] already investigated the coupling effect of the surface temperature on mantle dynamics by using simple parameterized convection models for Venus. In their model a positive feedback mechanism has been observed, i.e., an increase of the surface temperature leads to an increase of partial melt and hence an increase of atmosphere density and surface temperature. Applying our model to Venus, we show that an increase of surface temperature leads not only to an increase of partial melt in the mantle; it also

  1. Compositions of Hot Super-earth Atmospheres: Exploring Kepler Candidates

    NASA Astrophysics Data System (ADS)

    Miguel, Y.; Kaltenegger, L.; Fegley, B.; Schaefer, L.

    2011-12-01

    This paper outlines a simple approach to evaluate the atmospheric composition of hot rocky planets by assuming different types of planetary composition and using corresponding model calculations. To explore hot atmospheres above 1000 K, we model the vaporization of silicate magma and estimate the range of atmospheric compositions according to the planet's radius and semi-major axis for the Kepler 2011 February data release. Our results show five atmospheric types for hot, rocky super-Earth atmospheres, strongly dependent on the initial composition and the planet's distance to the star. We provide a simple set of parameters that can be used to evaluate atmospheric compositions for current and future candidates provided by the Kepler mission and other searches.

  2. COMPOSITIONS OF HOT SUPER-EARTH ATMOSPHERES: EXPLORING KEPLER CANDIDATES

    SciTech Connect

    Miguel, Y.; Kaltenegger, L.; Fegley, B.; Schaefer, L.

    2011-12-15

    This paper outlines a simple approach to evaluate the atmospheric composition of hot rocky planets by assuming different types of planetary composition and using corresponding model calculations. To explore hot atmospheres above 1000 K, we model the vaporization of silicate magma and estimate the range of atmospheric compositions according to the planet's radius and semi-major axis for the Kepler 2011 February data release. Our results show five atmospheric types for hot, rocky super-Earth atmospheres, strongly dependent on the initial composition and the planet's distance to the star. We provide a simple set of parameters that can be used to evaluate atmospheric compositions for current and future candidates provided by the Kepler mission and other searches.

  3. Atmospheric accelerations and the stability of dynamic supergiant atmospheres.

    NASA Astrophysics Data System (ADS)

    Nieuwenhuijzen, H.; de Jager, C.

    1995-10-01

    The goal of this paper is to study instability regions in the HR diagram, through a calculation of the atmospheric accelerations for spherically symmetric stars, in dynamic equilibrium, without using detailed atmospheric models. The input data are five primary data, viz.: the stellar luminosity L, the effective temperature T_eff_, the mass M, the rate of mass loss ˙(M), and the microturbulent velocity component ζmu_, while we assume the temperature for a reference atmospheric layer, an assumption that appears not to be critical. An iterative solution of the momentum equation, simultaneous with some other equations, yields values for the various accelerations acting on a stellar atmosphere and their algebraic sum g_eff_', the predicted effective acceleration. In the first part of the paper we compare this latter quantity with the g_eff_-value derived observationally from spectral studies of nine program stars and we find overall fair agreement. This supports the method as well as the values of the five input data. In part 2 we determine g'_eff_ in same way for the whole upper part of the Hertzsprung-Russell diagram by using statistical primary data on the mass (based on evolutionary calculations), on mass-loss and on microturbulence (shock-strengths). We find as a fairly general rule that, as stars move along their evolutionary track, and for time scales longer than the dynamic time scale of the atmosphere, the atmosphere continuously adapts to the new (L,T_eff_)-values and essentially remains stable. Current practice of determining the stability limit of stellar atmospheres by extrapolating hydrostatic models to the Eddington limit is not justified by this study. There is one exception: we find a small area around T_eff_=8300K and log(L/Lsun_)=5.7, where no solution is possible for evolved stars on their blueward evolutionary track; the stars in this area have in any case effective accelerations <1mm/s^2^: the "Yellow Evolutionary Void". In the third part we

  4. Dust particle dynamics in atmospheric dust devils

    NASA Astrophysics Data System (ADS)

    Izvekova, Yulia; Popel, Sergey

    2016-04-01

    Dust particle dynamics is modeled in the Dust Devils (DDs). DD is a strong, well-formed, and relatively long-lived whirlwind, ranging from small (half a meter wide and a few meters tall) to large (more than 100 meters wide and more than 1000 meters tall) in Earth's atmosphere. We develop methods for the description of dust particle charging in DDs, discuss the ionization processes in DDs, and model charged dust particle motion. Our conclusions are consistent with the fact that DD can lift a big amount of dust from the surface of a planet into its atmosphere. On the basis of the model we perform calculations and show that DDs are important mechanism for dust uplift in the atmospheres of Earth and Mars. Influence of DD electric field on dynamics of dust particles is investigated. It is shown that influence of the electric field on dust particles trajectories is significant near the ground. At some altitude (more then a quarter of the height of DD) influence of the electric field on dust particles trajectories is negligible. For the calculation of the dynamics of dust electric field can be approximated by effective dipole located at a half of the height of DD. This work was supported by the Russian Federation Presidential Program for State Support of Young Scientists (project no. MK-6935.2015.2).

  5. HPC simulations of the atmospheric composition climate of Bulgaria

    NASA Astrophysics Data System (ADS)

    Gadzhev, Georgi; Ganev, Kostadin; Miloshev, Nikolay; Syrakov, Dimiter; Prodanova, Maria

    2014-05-01

    Some extensive numerical simulations of the atmospheric composition fields in Bulgaria have been recently performed. The US EPA Model-3 system was chosen as a modelling tool. The system consists of three components: MM5 - the 5th generation PSU/NCAR Meso-meteorological Model used as meteorological pre-processor; CMAQ - the Community Multiscale Air Quality System CMAQ; SMOKE - the Sparse Matrix Operator Kernel Emissions Modelling System - the emission model. As the NCEP Global Analysis Data with 1 degree resolution was used as meteorological background, the MM5 and CMAQ nesting capabilities were applied for downscaling the simulations to a 3 km resolution over Bulgaria. The TNO emission inventory was used as emission input. Special pre-processing procedures are created for introducing temporal profiles and speciation of the emissions. The biogenic emissions of VOC are estimated by the model SMOKE. The numerical experiments have been carried out for different emission scenarios, which makes it possible the contribution of emissions from different source categories to be evaluated. The air pollution pattern is formed as a result of interaction of different processes, so knowing the contribution of each for different meteorological conditions and given emission spatial configuration and temporal behaviour could be interesting. Therefore the Models-3 'Integrated Process Rate Analysis' option is applied to discriminate the role of different dynamic and chemical processes for the air pollution formation. The obtained ensemble of numerical simulation results is extensive enough to allow statistical treatment - calculating not only the mean concentrations and different source categories contribution mean fields, but also standard deviations, skewness, etc. with their dominant temporal modes (seasonal and/or diurnal variations). Thus some basic facts about the atmospheric composition climate of Bulgaria can be retrieved from the simulation ensemble, which makes it possible

  6. Morphology, composition, and atmospheric processing of soot particles

    NASA Astrophysics Data System (ADS)

    Slowik, Jay G.

    Combustion-generated soot aerosols play an important role in climate forcing due to their strong light-absorbing properties. Quantitative measurement of BC is challenging because BC often occurs in highly non-spherical soot particles of complex morphology. The task is further complicated because of the lack of an unambiguous chemical definition of the material. Here we present the development and application of a new technique for determining particle morphology and composition. Simultaneous measurements of mobility diameter, vacuum aerodynamic diameter, and non-refractory composition were used to determine the particle mass, volume, density, composition, dynamic shape factor, and fractal dimension. Under certain conditions, particle surface area and the number and size of the primary spherules composing the soot fractal aggregates were also determined. The particle characterization technique described above was applied to the following four studies: (1) Characterization of flame-generated soot particles. Depending on flame conditions, either fractal or near-spherical particles were generated and their properties interpreted in terms of the mechanism for soot formation. (2) Coating and denuding experiments were performed on soot particles. The results yielded information about morphology changes to the entire soot particle and to the internal black carbon structure due to atmospheric processing. The denuding experiments also provided particle surface area, which was used to determine the atmospheric lifetime of fractal soot particles relative to spheres. (3) An inter-comparison study of instruments measuring the black carbon content of soot particles was conducted. The detailed characterization of soot particles enabled a number of assumptions about the operation of the selected instruments to be tested. (4) Ambient particles were sampled in Mexico City. In the early morning, ambient particles were detected with a fractal morphology similar to that of diesel

  7. Measurement of Atmospheric Composition from Geostationary Platforms

    NASA Technical Reports Server (NTRS)

    Bhartia, P. K.; Kawa, S. R.; Janz, S.; Herman, J. R.; Gleason, J. F.

    2008-01-01

    Satellite instruments flown since 1970 have had great success in elucidating the processes that control stratospheric ozone. In contrast, space-based data for tropospheric constituents that affect air quality and climate have only recently become available. While these datasets highlight the rapidly advancing capabilities of spacebased tropospheric sensors, they are also pointing to the limitations of sun-synchronous, low-earth orbiting (SSO/LEO) satellite platforms for making such measurements. In our talk we will highlight the science requirements for new missions and the technological and algorithmic approaches that we are developing to meet these requirements. From these studies a clear need for advanced atmospheric composition sensors has emerged that can be put on geostationary (GEO) platforms to provide 5 km horizontal resolution with 15-60 minutes repeat cycle. Such measurements have been high priority in the recently released Decadal Survey report by the US National Research Council. The need for GEO is driven not only by the science requirements to track rapidly changing pollution events but also by the need to provide altitude-resolved information about tropospheric constituents. Currently, with the exception of aerosols, it is not possible to derive profile information about lower tropospheric constituents from satellite measurements. New algorithmic approaches are being developed to obtain this information by combining UV and IR data, by monitoring the spatial and temporal structures of the constituents, and by using low-level clouds to separate boundary layer constituents from free troposphere. All these approaches require better spatial and temporal resolution than that provided by LEO sensors.

  8. Dynamic model of the Earth's upper atmosphere

    NASA Technical Reports Server (NTRS)

    Slowey, J. W.

    1984-01-01

    An initial modification to the MSF/J70 Thermospheric Model, in which the variations due to sudden geomagnetic disturbances upon the Earth's upper atmospheric density structure were modeled is presented. This dynamic model of the geomagnetic variation included is an improved version of one which SAO developed from the analysis of the ESRO 4 mass spectrometer data that was incorporated in the Jacchia 1977 model. The variation with geomagnetic local time as well as with geomagnetic latitude are included, and also the effects due to disturbance of the temperature profiles in the region of energy deposition.

  9. The Dynamics of the Atmospheric Radiation Environment at Aviation Altitudes

    NASA Technical Reports Server (NTRS)

    Stassinopoulos, Epaminondas G.

    2004-01-01

    Single Event Effects vulnerability of on-board computers that regulate the: navigational, flight control, communication, and life support systems has become an issue in advanced modern aircraft, especially those that may be equipped with new technology devices in terabit memory banks (low voltage, nanometer feature size, gigabit integration). To address this concern, radiation spectrometers need to fly continually on a multitude of carriers over long periods of time so as to accumulate sufficient information that will broaden our understanding of the very dynamic and complex nature of the atmospheric radiation environment regarding: composition, spectral distribution, intensity, temporal variation, and spatial variation.

  10. Model atmospheres for cool stars. [varying chemical composition

    NASA Technical Reports Server (NTRS)

    Johnson, H. R.

    1974-01-01

    This report contains an extensive series of model atmospheres for cool stars having a wide range in chemical composition. Model atmospheres (temperature, pressure, density, etc.) are tabulated, along with emergent energy flux distributions, limb darkening, and information on convection for selected models. The models are calculated under the usual assumptions of hydrostatic equilibrium, constancy of total energy flux (including transport both by radiation and convection) and local thermodynamic equilibrium. Some molecular and atomic line opacity is accounted for as a straight mean. While cool star atmospheres are regimes of complicated physical conditions, and these atmospheres are necessarily approximate, they should be useful for a number of kinds of spectral and atmospheric analysis.

  11. Isotopic composition of atmospheric hydrogen and methane

    USGS Publications Warehouse

    Bainbridge, A.E.; Suess, H.E.; Friedman, I.

    1961-01-01

    IN a recent communication, Bishop and Taylor1 express the opinion that the tritium concentration of free hydrogen in the atmosphere has been rising over the past ten years, with a doubling time of approximately 18 months. The authors suspect that artificial tritium was released into the atmosphere several years before the Castle test series in 1954, which is commonly assumed to have led to the first pronounced rise in the tritium concentration of terrestrial surface water. Bishop and Taylor's communication includes a diagram of the logarithms of all the experimentally determined tritium values in free atmospheric hydrogen plotted against time. The plot shows that the values follow a straight line that includes the first value obtained by Faltings and Harteck2 on atmospheric hydrogen collected in 1948. ?? 1961 Nature Publishing Group.

  12. Lunar atmospheric composition results from Apollo 17

    NASA Technical Reports Server (NTRS)

    Hoffmann, J. H.; Hodges, R. R., Jr.; Johnson, F. S.; Evans, D. E.

    1973-01-01

    The Apollo 17 mass spectrometer has confirmed the existence of helium, neon, argon, and possibly molecular hydrogen in the lunar atmosphere. Helium and neon concentrations are in agreement with model predictions based on the solar wind as a source and their being noncondensable gases. Ar-40 and Ar-36 both exhibit a predawn enhancement which indicates that they are condensable gases on the nightside and are re-released into the atmosphere at the sunrise terminator. Hydrogen probably exists in the lunar atmosphere in the molecular rather than atomic state, having been released from the surface in the molecular form. Total nighttime gas concentration of known species in the lunar atmosphere is 200,000 molecules/cu cm.

  13. Isotopic composition of atmospheric moisture from pan water evaporation measurements.

    PubMed

    Devi, Pooja; Jain, Ashok Kumar; Rao, M Someshwer; Kumar, Bhishm

    2015-01-01

    A continuous and reliable time series data of the stable isotopic composition of atmospheric moisture is an important requirement for the wider applicability of isotope mass balance methods in atmospheric and water balance studies. This requires routine sampling of atmospheric moisture by an appropriate technique and analysis of moisture for its isotopic composition. We have, therefore, used a much simpler method based on an isotope mass balance approach to derive the isotopic composition of atmospheric moisture using a class-A drying evaporation pan. We have carried out the study by collecting water samples from a class-A drying evaporation pan and also by collecting atmospheric moisture using the cryogenic trap method at the National Institute of Hydrology, Roorkee, India, during a pre-monsoon period. We compared the isotopic composition of atmospheric moisture obtained by using the class-A drying evaporation pan method with the cryogenic trap method. The results obtained from the evaporation pan water compare well with the cryogenic based method. Thus, the study establishes a cost-effective means of maintaining time series data of the isotopic composition of atmospheric moisture at meteorological observatories. The conclusions drawn in the present study are based on experiments conducted at Roorkee, India, and may be examined at other regions for its general applicability.

  14. Geomagnetic Disturbances Caused by Internal Atmospheric Dynamics

    NASA Technical Reports Server (NTRS)

    Sonneman, G.

    1984-01-01

    It is commonly believed that geomagnetic disturbances are caused by external influences connected with the solar wind. The 27-day recurrence of perturbations seems to be a strong hint for this interaction. But frequently geomagnetic disturbances occur without any relation to sunspot numbers or radiowave fluxes. This was one of the reasons for introducing hypothetical M-regions on the Sun and their relation to solar wind activities. Only one half of the variance of the geomagnetic AL-index could be related to the solar wind. Therefore it is concluded that internal processes of the magnetosphere were responsible for additional geomagnetic activity. Arguments, which might lead to the suggestion of geomagnetic disturbances as being caused by internal atmospheric dynamics are discussed and a rather preliminary scenario of those processes is proposed.

  15. Dynamics investigation in the Venus upper atmosphere

    NASA Astrophysics Data System (ADS)

    Migliorini, A.; Altieri, F.; Shakun, A.; Zasova, L.; Piccioni, G.; Bellucci, G.

    The O_2 nightglow emissions in the infrared spectral range are important features to investigate dynamics at the mesospheric altitudes, in the planetary atmosphere. In this work, we analyzed the profiles obtained at limb by the VIRTIS spectrometer on board the Venus Express mission, acquired during the mission period from 2006-07-05 to 2008-08-15 to investigate possible gravity waves characteristics at the airglow altitudes. Indeed, several profiles present double peaked structures that can be interpreted as due to gravity waves. In analogy to the Earth's and Mars cases, we use a well-known theory to model the O_2 nightglow emissions affected by gravity waves propagation, in order to support this thesis and derive the waves properties. We discuss results from 30 profiles showing double peaked structures, focusing on vertical wavelength and wave amplitude of the possible gravity waves. On average, the double peaked profiles are compatible with the effects of gravity waves with a vertical wavelength ranging between 7 and 16 km, and wave amplitude of 3-14%. A comparison with gravity waves properties in the Mars and Earth's atmospheres, using the same theory, is also proposed \\citep{altieri_2014}. \\ The research is supported by ASI (contract ASI-INAF I/050/10/0).

  16. Some numerically studies of the atmospheric composition climate of Bulgaria

    NASA Astrophysics Data System (ADS)

    Gadzhev, G. K.; Ganev, K. G.; Prodanov, M.; Syrakov, D. E.; Miloshev, N. G.; Georgiev, G. J.

    2013-10-01

    Some extensive numerical simulations of the atmospheric composition fields in Bulgaria have been recently performed. The US EPA Model-3 system was chosen as a modelling tool. The system consists of three components: MM5 - the 5th generation PSU/NCAR Meso-meteorological Model used as meteorological pre-processor; CMAQ - the Community Multiscale Air Quality System CMAQ; SMOKE - the Sparse Matrix Operator Kernel Emissions Modelling System - the emission model [4]. As the NCEP Global Analysis Data with 1 degree resolution was used as meteorological background, the MM5 and CMAQ nesting capabilities were applied for downscaling the simulations to a 3 km resolution over Bulgaria. The TNO emission inventory was used as emission input. Special pre-processing procedures are created for introducing temporal profiles and speciation of the emissions. The biogenic emissions of VOC are estimated by the model SMOKE. The numerical experiments have been carried out for different emission scenarios, which makes it possible the contribution of emissions from different source categories to be evaluated. The air pollution pattern is formed as a result of interaction of different processes, so knowing the contribution of each for different meteorological conditions and given emission spatial configuration and temporal behaviour could be interesting. Therefore the Models-3 "Integrated Process Rate Analysis" option is applied to discriminate the role of different dynamic and chemical processes for the air pollution formation. The obtained ensemble of numerical simulation results is extensive enough to allow statistical treatment - calculating not only the mean concentrations and different source categories contribution mean fields, but also standard deviations, skewness, etc. with their dominant temporal modes (seasonal and/or diurnal variations). Thus some basic facts about the atmospheric composition climate of Bulgaria can be retrieved from the simulation ensemble.

  17. Chapter 13. Atmospheric Dynamics and Meteorology

    NASA Technical Reports Server (NTRS)

    Flasar, F. M.; Baines, K. H.; Bird, M. K.; Tokano, T.

    2009-01-01

    Titan, after Venus, is the second example in the solar system of an atmosphere with a global cyclostrophic circulation, but in this case a circulation that has a strong seasonal modulation in the middle atmosphere. Direct measurement of Titan's winds, particularly observations tracking the Huygens probe at 10 deg S, indicate that the zonal winds are mostly in the sense of the satellite's rotation. They generally increase with altitude and become cyclostrophic near 35 km above the surface. An exception to this is a sharp minimum centered near 75 km, where the wind velocity decreases to nearly zero. Zonal winds derived from temperatures retrieved from Cassini orbiter measurements, using the thermal wind equation, indicate a strong winter circumpolar vortex, with maximum winds of 190 m/s at mid northern latitudes near 300 km. Above this level, the vortex decays. Curiously, the stratospheric zonal winds and temperatures in both hemispheres are symmetric about a pole that is offset from the surface pole by about 4 deg. The cause of this is not well understood, but it may reflect the response of a cyclostrophic circulation to the onset between the equator, where the distance to the rotation axis is greatest, and the seasonally varying subsolar latitude. The mean meridional circulation can be inferred from the temperature field and the meridional distribution of organic molecules and condensates and hazes. Both the warm temperatures near 400 km and the enhanced concentration of several organic molecules suggest subsidence in the north polar region during winter and early spring. Stratospheric condensates are localized at high northern latitudes, with a sharp cut-off near 50 deg N. Titan's winter polar vortex appears to share many of the same characteristics of isolating high and low-latitude air masses as do the winter polar vortices on Earth that envelop the ozone holes. Global mapping of temperatures, winds, and composition in the troposphere, by contrast, is incomplete

  18. Radiative and dynamical modeling of Jupiter's atmosphere

    NASA Astrophysics Data System (ADS)

    Guerlet, Sandrine; Spiga, Aymeric

    2016-04-01

    Jupiter's atmosphere harbours a rich meteorology, with alternate westward and eastward zonal jets, waves signatures and long-living storms. Recent ground-based and spacecraft measurements have also revealed a rich stratospheric dynamics, with the observation of thermal signatures of planetary waves, puzzling meridional distribution of hydrocarbons at odds with predictions of photochemical models, and a periodic equatorial oscillation analogous to the Earth's quasi-biennal oscillation and Saturn's equatorial oscillation. These recent observations, along with the many unanswered questions (What drives and maintain the equatorial oscillations? How important is the seasonal forcing compared to the influence of internal heat? What is the large-scale stratospheric circulation of these giant planets?) motivated us to develop a complete 3D General Circulation Model (GCM) of Saturn and Jupiter. We aim at exploring the large-scale circulation, seasonal variability, and wave activity from the troposphere to the stratosphere of these giant planets. We will briefly present how we adapted our existing Saturn GCM to Jupiter. One of the main change is the addition of a stratospheric haze layer made of fractal aggregates in the auroral regions (poleward of 45S and 30N). This haze layer has a significant radiative impact by modifying the temperature up to +/- 15K in the middle stratosphere. We will then describe the results of radiative-convective simulations and how they compare to recent Cassini and ground-based temperature measurements. These simulations reproduce surprisingly well some of the observed thermal vertical and meridional gradients, but several important mismatches at low and high latitudes suggest that dynamics also plays an important role in shaping the temperature field. Finally, we will present full GCM simulations and discuss the main resulting features (waves and instabilities). We will also and discuss the impact of the choice of spatial resolution and

  19. Composition and physics of the lunar atmosphere.

    NASA Technical Reports Server (NTRS)

    Hoffman, J. H.; Hodges, R. R., Jr.; Johnson, F. S.; Evans , D. E.

    1973-01-01

    The existence in the lunar atmosphere of helium, neon, argon, and possibly molecular hydrogen has been confirmed by the Apollo 17 mass spectrometer. The observed helium concentrations and distribution agree closely with model predictions for a non-condensable gas based on a solar wind source, thermal escape and a Monte Carlo random walk calculated longitudinal distribution. Heavier gases are lost by photoionization and subsequent sweeping away by the solar wind electric field. The observed nighttime neon concentration of 80,000 molecules per cu cm is consistent with expected amounts. Argon, however, is adsorbed on the lunar surface late at night when the surface temperature is lowest. It shows the expected predawn enhancement exhibited by condensable gases released into the atmosphere at the sunrise terminator. Hydrogen appears to exist in the molecular rather than atomic state. Its observed concentration is less than a factor of 3 higher than that predicted by a model similar to that used for helium.

  20. Clouds Composition in Super-Earth Atmospheres: Chemical Equilibrium Calculations

    NASA Astrophysics Data System (ADS)

    Kempton, Eliza M.-R.; Mbarek, Rostom

    2015-12-01

    Attempts to determine the composition of super-Earth atmospheres have so far been plagued by the presence of clouds. Yet the theoretical framework to understand these clouds is still in its infancy. For the super-Earth archetype GJ 1214b, KCl, Na2S, and ZnS have been proposed as condensates that would form under the condition of chemical equilibrium, if the planet’s atmosphere has a bulk composition near solar. Condensation chemistry calculations have not been presented for a wider range of atmospheric bulk composition that is to be expected for super-Earth exoplanets. Here we provide a theoretical context for the formation of super-Earth clouds in atmospheres of varied composition by determining which condensates are likely to form, under the assumption of chemical equilibrium. We model super-Earth atmospheres assuming they are formed by degassing of volatiles from a solid planetary core of chondritic material. Given the atomic makeup of these atmospheres, we minimize the global Gibbs free energy of over 550 gases and condensates to obtain the molecular composition of the atmospheres over a temperature range of 350-3,000 K. Clouds should form along the temperature-pressure boundaries where the condensed species appear in our calculations. The super-Earth atmospheres that we study range from highly reducing to oxidizing and have carbon to oxygen (C:O) ratios that are both sub-solar and super-solar, thereby spanning a diverse range of atmospheric composition that is appropriate for low-mass exoplanets. Some condensates appear across all of our models. However, the majority of condensed species appear only over specific ranges of H:O and C:O ratios. We find that for GJ 1214b, KCl is the primary cloud-forming condensate at solar composition, in agreement with previous work. However, for oxidizing atmospheres, where H:O is less than unity, K2SO4 clouds form instead. For carbon-rich atmospheres with super-solar C:O ratios, graphite clouds additionally appear. At

  1. Saturn's Polar Atmosphere: Seasonal Change and Composition from Cassini

    NASA Astrophysics Data System (ADS)

    Fletcher, Leigh; Orton, Glenn; Baines, Kevin; Momary, Thomas; Irwin, Patrick; Roos-Serote, Maarten; Teanby, Nicholas; Merlet, Cecile; Read, Peter

    Cassini's prime mission permitted the first detailed infrared studies of the polar atmosphere of Saturn, under both southern summertime and northern wintertime conditions. Both poles exhibited small, discrete warm vortices (`hotspots') in the troposphere and stratosphere, which were depleted in disequilibrium species and hazes, surrounded by strong prograde jets and characterised by distinct `eyewalls.' In addition, the south polar stratosphere had an extensive warm polar `hood' between 70-90° S, which was expected to be seasonal in nature and related to the presence of high-altitude stratospheric hazes, localised at the south pole. Finally, infrared observations revealed the continued presence of the northern hexagon discovered during the Voyager encounter in 1981, but observed no comparable features in the south. In August 2009 Saturn reached its equinox, so that the cold northern pole emerged into sunlight for the first time in almost 15 years. We present a time series of Composite Infrared Spectrom-eter (CIRS) observations from 2004 to 2009 which demonstrate (a) the continued presence of the polar vortices under spring and autumnal conditions; (b) the cooling of the southern stratospheric hood; and (c) the persistence of the northern hexagon. These are compared with ground-based observations of Saturn from the Very Large Telescope VISIR instrument at the time of ring-plane crossing to study compositional asymmetries between the two poles. Fur-thermore, we derive the spatial distribution of aerosols, phosphine, ammonia and arsine in the north polar hotspot and hexagon from Cassini VIMS 4.5-5.1 µm observations to reveal the mor-phology and composition of these dynamical features. These results will be discussed in terms of our present understanding of the polar circulation systems on Saturn, and their response to seasonal variations of insolation.

  2. Interior and its implications for the atmosphere. [effects of Titan interior structure on its atmospheric composition

    NASA Technical Reports Server (NTRS)

    Lewis, J. S.

    1974-01-01

    The bulk composition and interior structure of Titan required to explain the presence of a substantial methane atmosphere are shown to imply the presence of solid CH4 - 7H2O in Titan's primitive material. Consideration of the possible composition and structure of the present atmosphere shows plausible grounds for considering models with total atmospheric pressures ranging from approximately 20 mb up to approximately 1 kb. Expectations regarding the physical state of the surface and its chemical composition are strongly conditioned by the mass of atmosphere believed to be present. A surface of solid CH4, liquid CH4 solid, CH4 hydrate, H2O ice, aqueous NH3 solution, or even a non-surface of supercritical H2O-NH3-CH4 fluid could be rationalized.

  3. Turbulence dynamics in unsteady atmospheric flows

    NASA Astrophysics Data System (ADS)

    Momen, Mostafa; Bou-Zeid, Elie

    2016-11-01

    Unsteady pressure-gradient forcing in geophysical flows challenges the quasi-steady state assumption, and can strongly impact the mean wind and higher-order turbulence statistics. Under such conditions, it is essential to understand when turbulence is in quasi-equilibrium, and what are the implications of unsteadiness on flow characteristics. The present study focuses on the unsteady atmospheric boundary layer (ABL) where pressure gradient, Coriolis, buoyancy, and friction forces interact. We perform a suite of LES with variable pressure-gradient. The results indicate that the dynamics are mainly controlled by the relative magnitudes of three time scales: Tinertial, Tturbulence, and Tforcing. It is shown that when Tf Tt , the turbulence is no longer in a quasi-equilibrium state due to highly complex mean-turbulence interactions; consequently, the log-law and turbulence closures are no longer valid in these conditions. However, for longer and, surprisingly, for shorter forcing times, quasi-equilibrium is maintained. Varying the pressure gradient in the presence of surface buoyancy fluxes primarily influences the buoyant destruction in the stable ABLs, while under unstable conditions it mainly influences the transport terms. NSF-PDM under AGS-10266362. Cooperative Institute for Climate Science, NOAA-Princeton University under NA08OAR4320752. Simulations performed at NCAR, and Della server at Princeton University.

  4. Nonlinear dynamics and predictability in the atmospheric sciences

    SciTech Connect

    Ghil, M.; Kimoto, M.; Neelin, J.D. )

    1991-01-01

    Systematic applications of nonlinear dynamics to studies of the atmosphere and climate are reviewed for the period 1987-1990. Problems discussed include paleoclimatic applications, low-frequency atmospheric variability, and interannual variability of the ocean-atmosphere system. Emphasis is placed on applications of the successive bifurcation approach and the ergodic theory of dynamical systems to understanding and prediction of intraseasonal, interannual, and Quaternary climate changes.

  5. ATMOSPHERIC CIRCULATION AND COMPOSITION OF GJ1214b

    SciTech Connect

    Menou, Kristen

    2012-01-15

    The exoplanet GJ1214b presents an interesting example of compositional degeneracy for low-mass planets. Its atmosphere may be composed of water, super-solar or solar metallicity material. We present atmospheric circulation models of GJ1214b for these three compositions, with explicit gray radiative transfer and an optional treatment of MHD bottom drag. All models develop strong, superrotating zonal winds ({approx}1-2 km s{sup -1}). The degree of eastward heat advection, which can be inferred from secondary eclipse and thermal phase curve measurements, varies greatly between the models. These differences are understood as resulting from variations in the radiative times at the thermal photosphere, caused by separate molecular weight and opacity effects. Our GJ1214b models illustrate how atmospheric circulation can be used as a probe of composition for similar tidally locked exoplanets in the mini-Neptune/waterworld class.

  6. Linking atmospheric composition data across data types and national boundaries

    NASA Astrophysics Data System (ADS)

    Schultz, Martin; Lyapina, Olga; Schröder, Sabine; Stein, Olaf; Mallmann, Daniel

    2016-04-01

    The field of atmospheric composition research involves the management of data sources from various disciplines such as meteorology, chemistry, (radiation) physics, emission inventories, etc. The output from global and regional chemistry climate models, chemistry transport models, and air quality models presents considerable challenges due to the manifold variables of interest and the multitude of diagnostics needed in order to interpret the results. Furthermore, many observations of atmospheric composition exist from different platforms involving different geometries, time resolutions, size spectra, etc. Due to the fact that few observation networks are globally coordinated, various representations of data formats and metadata definitions exist. For example, there is no unique agreement on chemical species names and in many networks, national languages are used to document the data. We will present a summary of the issues involving global interoperability of atmospheric composition data including the aspects of data volume, data compexity and metadata standardisation, and we will demonstrate various activities carried out in Jülich and internationally to overcome these challenges. Specifically, we will describe the current implementation and plans for the Copernicus Atmosphere Monitoring Service boundary condition service (http://ows-server.iek.fz-juelich.de), the design of the JOIN web interface (https://join.fz-juelich.de), and the activities for building an ontology of atmospheric composition vocabulary (https://ontology.geodab.eu/).

  7. Modeling the effects of atmospheric emissions on groundwater composition

    SciTech Connect

    Brown, Theresa Jean

    1994-01-01

    A composite model of atmospheric, unsaturated and groundwater transport is developed to evaluate the processes determining the distribution of atmospherically derived contaminants in groundwater systems and to test the sensitivity of simulated contaminant concentrations to input parameters and model linkages. One application is to screen specific atmospheric emissions for their potential in determining groundwater age. Temporal changes in atmospheric emissions could provide a recognizable pattern in the groundwater system. The model also provides a way for quantifying the significance of uncertainties in the tracer source term and transport parameters on the contaminant distribution in the groundwater system, an essential step in using the distribution of contaminants from local, point source atmospheric emissions to examine conceptual models of groundwater flow and transport.

  8. Earth-atmosphere evolution based on new determination of Devonian atmosphere Ar isotopic composition

    NASA Astrophysics Data System (ADS)

    Stuart, Finlay M.; Mark, Darren F.; Gandanger, Pierre; McConville, Paul

    2016-07-01

    The isotopic composition of the noble gases, in particular Ar, in samples of ancient atmosphere trapped in rocks and minerals provides the strongest constraints on the timing and rate of Earth atmosphere formation by degassing of the Earth's interior. We have re-measured the isotopic composition of argon in the Rhynie chert from northeast Scotland using a high precision mass spectrometer in an effort to provide constraints on the composition of Devonian atmosphere. Irradiated chert samples yield 40Ar/36Ar ratios that are often below the modern atmosphere value. The data define a 40Ar/36Ar value of 289.5 ± 0.4 at K/36Ar = 0. Similarly low 40Ar/36Ar are measured in un-irradiated chert samples. The simplest explanation for the low 40Ar/36Ar is the preservation of Devonian atmosphere-derived Ar in the chert, with the intercept value in 40Ar-39Ar-36Ar space representing an upper limit. In this case the Earth's atmosphere has accumulated only 3% (5.1 ± 0.4 ×1016 mol) of the total 40Ar inventory since the Devonian. The average accumulation rate of 1.27 ± 0.09 ×108 mol40Ar/yr overlaps the rate over the last 800 kyr. This implies that there has been no resolvable temporal change in the outgassing rate of the Earth since the mid-Palaeozoic despite the likely episodicity of Ar degassing from the continental crust. Incorporating the new Devonian atmosphere 40Ar/36Ar into the Earth degassing model of Pujol et al. (2013) provides the most precise constraints on atmosphere formation so far. The atmosphere formed in the first ∼100 Ma after initial accretion during a catastrophic degassing episode. A significant volume of 40Ar did not start to accumulate in the atmosphere until after 4 Ga which implies that stable K-rich continental crust did not develop until this time.

  9. Atmospheric Composition Data and Information Services Center (ACDISC)

    NASA Technical Reports Server (NTRS)

    Kempler, S.

    2005-01-01

    NASA's GSFC Earth Sciences (GES) Data and Information and Data Services Center (DISC) manages the archive, distribution and data access for atmospheric composition data from AURA'S OMI, MLS, and hopefully one day, HIRDLS instruments, as well as heritage datasets from TOMS, UARS, MODIS, and AIRS. This data is currently archived in the GES Distributed Active Archive Center (DAAC). The GES DISC has begun the development of a community driven data management system that's sole purpose is to manage and provide value added services to NASA's Atmospheric Composition (AC) Data. This system, called the Atmospheric Composition Data and Information Services Center (ACDISC) will provide access all AC datasets from the above mentioned instruments, as well as AC datasets residing at remote archive sites (e.g, LaRC DAAC) The goals of the ACDISC are to: 1) Provide a data center for Atmospheric Scientists, guided by Atmospheric Scientists; 2) Be absolutely responsive to the data and data service needs of the Atmospheric Composition (AC) community; 3) Provide services (i.e., expertise) that will facilitate the effortless access to and usage of AC data; 4) Collaborate with AC scientists to facilitate the use of data from multiple sensors for long term atmospheric research. The ACDISC is an AC specific, user driven, multi-sensor, on-line, easy access archive and distribution system employing data analysis and visualization, data mining, and other user requested techniques that facilitate science data usage. The purpose of this presentation is to provide the evolution path that the GES DISC in order to better serve AC data, and also to receive continued community feedback and further foster collaboration with AC data users and providers.

  10. Atmospheric composition affects heat- and mass-transfer processes

    NASA Technical Reports Server (NTRS)

    Blakely, R. L.; Nelson, W. G.

    1970-01-01

    For environmental control system functions sensitive to atmospheric composition, components are test-operated in helium-oxygen and nitrogen-oxygen mixtures, pure oxygen, and air. Transient heat- and mass-transfer tests are conducted for carbon dioxide adsorption on molecular sieve and for water vapor adsorption on silica gel.

  11. Atmospheric Dynamics of Uranus and Neptune: Theoretical Considerations

    NASA Technical Reports Server (NTRS)

    Ingersoll, A. P.

    1984-01-01

    The atmospheric dynamics of neptune and uranus are investigated. Uranus, because of its pole on orientation and low internal heat source, is in a dynamically different atmospheric regime from Jupiter and Saturn. Neptune resembles Jupiter and Saturn in orientation and internal heating, but its extremely long radiative time constant puts Neptune in a different class. Voyager observations of seasonal temperature gradients, equator to pole temperature gradients, infrared emission, Bond albedo, possible cloud structures (bands, spots, eddies), and cloud motions can be used to improve the ability to classify planetary atmospheres according to their dynamical regimes.

  12. Theoretical and experimental investigations of upper atmosphere dynamics

    NASA Technical Reports Server (NTRS)

    Roper, R. G.; Edwards, H. D.

    1980-01-01

    A brief overview of the significant contributions made to the understanding of the dynamics of the Earth's upper atmosphere is presented, including the addition of winds and diffusion to the semi-empirical Global Reference Atmospheric Model developed for the design phase of the Space Shuttle, reviews of turbulence in the lower thermosphere, the dynamics of the equatorial mesopause, stratospheric warming effects on mesopause level dynamics, and the relevance of these studies to the proposed Middle Atmosphere Program (1982-85). A chronological bibliography, with abstracts of all papers published, is also included.

  13. Automated Atmospheric Composition Dataset Level Metadata Discovery. Difficulties and Surprises

    NASA Astrophysics Data System (ADS)

    Strub, R. F.; Falke, S. R.; Kempler, S.; Fialkowski, E.; Goussev, O.; Lynnes, C.

    2015-12-01

    The Atmospheric Composition Portal (ACP) is an aggregator and curator of information related to remotely sensed atmospheric composition data and analysis. It uses existing tools and technologies and, where needed, enhances those capabilities to provide interoperable access, tools, and contextual guidance for scientists and value-adding organizations using remotely sensed atmospheric composition data. The initial focus is on Essential Climate Variables identified by the Global Climate Observing System - CH4, CO, CO2, NO2, O3, SO2 and aerosols. This poster addresses our efforts in building the ACP Data Table, an interface to help discover and understand remotely sensed data that are related to atmospheric composition science and applications. We harvested GCMD, CWIC, GEOSS metadata catalogs using machine to machine technologies - OpenSearch, Web Services. We also manually investigated the plethora of CEOS data providers portals and other catalogs where that data might be aggregated. This poster is our experience of the excellence, variety, and challenges we encountered.Conclusions:1.The significant benefits that the major catalogs provide are their machine to machine tools like OpenSearch and Web Services rather than any GUI usability improvements due to the large amount of data in their catalog.2.There is a trend at the large catalogs towards simulating small data provider portals through advanced services. 3.Populating metadata catalogs using ISO19115 is too complex for users to do in a consistent way, difficult to parse visually or with XML libraries, and too complex for Java XML binders like CASTOR.4.The ability to search for Ids first and then for data (GCMD and ECHO) is better for machine to machine operations rather than the timeouts experienced when returning the entire metadata entry at once. 5.Metadata harvest and export activities between the major catalogs has led to a significant amount of duplication. (This is currently being addressed) 6.Most (if not

  14. Historical aspects of radar atmospheric dynamics

    NASA Technical Reports Server (NTRS)

    Kato, Susumu

    1989-01-01

    A review of the history of radar techniques which have been applied to atmospheric observation is given. The author starts with ionosphere observation with the ionosonde, symbolizing as it does the earliest history of radar observation, and proceeds to later developments in radar observation such as the use of partial reflection, meteor, and incoherent scatter radars. Mesosphere stratosphere troposphere (MST) radars are discussed in terms of lower atmosphere observation.

  15. Pioneer 10 Jupiter atmospheric definition results: A summary. [Jupiter atmosphere composition measurements

    NASA Technical Reports Server (NTRS)

    Wolfe, J.; Kliore, A.

    1974-01-01

    The various entry probes for measuring outer planetary atmospheric compositions are discussed. Considered are chemical components and physical accumulation processes observable by spectroscopic studies, as well as pressure gauges, temperature gauges, accelerometers, nephelometers, and visible and infrared sensors for determining abundances.

  16. Current Scientific Issues in Large Scale Atmospheric Dynamics

    NASA Technical Reports Server (NTRS)

    Miller, T. L. (Compiler)

    1986-01-01

    Topics in large scale atmospheric dynamics are discussed. Aspects of atmospheric blocking, the influence of transient baroclinic eddies on planetary-scale waves, cyclogenesis, the effects of orography on planetary scale flow, small scale frontal structure, and simulations of gravity waves in frontal zones are discussed.

  17. Isotopic composition of precipitation during different atmospheric circulation patterns

    NASA Astrophysics Data System (ADS)

    Brenčič, Mihael; Kononova, Nina; Vreča, Polona

    2016-04-01

    Precipitation generating processes depend on atmospheric circulation patterns and consequently it is expected that its water stable isotopic composition of hydrogen and oxygen is related to them. Precipitation generated at similar atmospheric circulation patterns should have similar empirical distribution of δ2H and δ18O values. There are several approaches in which atmospheric circulation patterns are classified as elementary air circulation mechanisms - ECM; in our approach we have applied Dzerdzeevskii classification. Two types of models of relation between ECM and isotopic composition of precipitation are proposed; first is based on the linear combination of δ2H and δ18O values with precipitation amount weighted average (Brenčič et al., 2015) and the second new one is based on the multiple regression approach. Both approaches make possible also to estimate empirical distributions' dispersion parameters. Application of the models is illustrated on the precipitation records from Ljubljana and Portorož GNIP stations, Slovenia. Estimated values of the parameters for empirical distributions of δ2H and δ18O of each ECM subtype have shown that calculated estimates are reasonable. Brenčič, M., Kononova, N.K., Vreča, P., 2015: Relation between isotopic composition of precipitation and atmospheric circulation patterns. Journal of Hydrology 529, 1422-1432: doi: 10.1016/j.jhydrol.2015.08.040

  18. Characteristics of wavelike fluctuations in Dynamics Explorer neutral composition data

    NASA Technical Reports Server (NTRS)

    Hedin, A. E.; Mayr, H. G.

    1987-01-01

    Wavelike fluctuations in neutral composition data obtained with the neutral atmospheric composition system quadrupole mass spectrometer carried aboard the Dynamics Explorer (DE 2) satellite are at a maximum in the vicinity of the magnetic poles. Typical rms amplitudes near the poles for N2, O, He, and Ar fluctuations in the 400- to 4000-km-wavelength band are found to be 11, 6, 6, and 20 percent, respectively. Amplitudes near the equator are roughly a third of the polar amplitudes, and activity in the 50- to 400-km-wavlength band is roughly 20 percent of the longer-wavelength activity.

  19. The San Marco 3 neutral atmosphere composition experiment

    NASA Technical Reports Server (NTRS)

    Pelz, D. T.; Newton, G. P.; Kasprzak, W. T.; Clem, T. D.

    1973-01-01

    The experimental instrumentation of the San Marco 3 satellite is described along with the calibration and operation. The instrumentation for the following experiments was included: an air density experiment for measuring the instantaneous drag force, and thus the neutral particle total mass density; a neutral atmosphere composition experiment for measuring the densities of helium, atomic and molecular oxygen, molecular nitrogen and argon; and a neutral atmosphere temperature experiment to determine the gas kinetic temperature by measuring molecular nitrogen density variations in an orificed spherical chamber as a function of angle of attack.

  20. Exploration Spacecraft and Space Suit Internal Atmosphere Pressure and Composition

    NASA Technical Reports Server (NTRS)

    Lange, Kevin; Duffield, Bruce; Jeng, Frank; Campbell, Paul

    2005-01-01

    The design of habitat atmospheres for future space missions is heavily driven by physiological and safety requirements. Lower EVA prebreathe time and reduced risk of decompression sickness must be balanced against the increased risk of fire and higher cost and mass of materials associated with higher oxygen concentrations. Any proposed increase in space suit pressure must consider impacts on space suit mass and mobility. Future spacecraft designs will likely incorporate more composite and polymeric materials both to reduce structural mass and to optimize crew radiation protection. Narrowed atmosphere design spaces have been identified that can be used as starting points for more detailed design studies and risk assessments.

  1. Computational Fluid Dynamics for Atmospheric Entry

    DTIC Science & Technology

    2009-09-01

    Atmospheric entry 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT... Atmospheric Entry 15 - 4 RTO-EN-AVT-162 and was performed on 16 million element hybrid unstructured grid. Not shown in this image is that the...conserved quantities and the non-conserved quantities such as pressure and temperature are discussed in this section. The total energy, E, is made up of

  2. Europa's Oxygen Atmosphere: Effects due to Regolith Porosity and Composition

    NASA Astrophysics Data System (ADS)

    Cassidy, T. A.; Johnson, R. E.

    2006-05-01

    The surfaces of "airless" bodies in our solar system are covered by porous regoliths, granular surfaces generated by micrometeor impact. Europa's tenuous neutral atmosphere is generated by UV and plasma irradiation of and sublimation from this regolith. Therefore, in addition to the atmosphere above the surface, there is a substantial amount of gas in the porous regolith. The effect of the regolith on the source processes and sinks are typically neglected in modeling the spatial distribution and composition of the atmosphere. The regolith complicates processes such as sputtering, the ejection of mostly neutral atoms and molecules due to energetic ion flux, because the incident ions encounter surfaces at a variety of angles, rather than one angle as usually assumed. Also, most ejecta produced within a regolith no longer have a direct line to space. If ejecta do not stick to or react with grain surfaces, then it may be safely assumed that the majority of ejecta will interact with grain surfaces before leaving the regolith. Similarly, a returning non-sticking particle experiences numerous interactions with grains below the nominal surface. As compared to a flat, smooth planetary surface, these many interactions enhance the probability of chemical reactions or sticking. F. Leblanc and R.E. Johnson have shown that the sticking coefficient is critical in describing the alkali atmosphere at Mercury and likely Europa. The regolith will also affect the velocity distribution of non-sticking ejecta and atmospheric species, which will affect the population of the Europa neutral torus. In this presentation the effect of regolith on the source and sink processes is demonstrated by generating the gravitationally bound and escaping components of the ballistic Europan atmosphere with and without regolith effects. Assuming that O2 can react in the regolith where there is a high sulfur content, we can generate a morphology roughly consistent with HST observations by McGrath and

  3. Dynamics of atmospheres with a non-dilute condensible component.

    PubMed

    Pierrehumbert, Raymond T; Ding, Feng

    2016-06-01

    The diversity of characteristics for the host of recently discovered exoplanets opens up a great deal of fertile new territory for geophysical fluid dynamics, particularly when the fluid flow is coupled to novel thermodynamics, radiative transfer or chemistry. In this paper, we survey one of these new areas-the climate dynamics of atmospheres with a non-dilute condensible component, defined as the situation in which a condensible component of the atmosphere makes up a substantial fraction of the atmospheric mass within some layer. Non-dilute dynamics can occur for a wide range of condensibles, generically applying near both the inner and the outer edges of the conventional habitable zone and in connection with runaway greenhouse phenomena. It also applies in a wide variety of other planetary circumstances. We first present a number of analytical results developing some key features of non-dilute atmospheres, and then show how some of these features are manifest in simulations with a general circulation model adapted to handle non-dilute atmospheres. We find that non-dilute atmospheres have weak horizontal temperature gradients even for rapidly rotating planets, and that their circulations are largely barotropic. The relative humidity of the condensible component tends towards 100% as the atmosphere becomes more non-dilute, which has important implications for runaway greenhouse thresholds. Non-dilute atmospheres exhibit a number of interesting organized convection features, for which there is not yet any adequate theoretical understanding.

  4. Dynamics of atmospheres with a non-dilute condensible component

    NASA Astrophysics Data System (ADS)

    Pierrehumbert, Raymond T.; Ding, Feng

    2016-06-01

    The diversity of characteristics for the host of recently discovered exoplanets opens up a great deal of fertile new territory for geophysical fluid dynamics, particularly when the fluid flow is coupled to novel thermodynamics, radiative transfer or chemistry. In this paper, we survey one of these new areas-the climate dynamics of atmospheres with a non-dilute condensible component, defined as the situation in which a condensible component of the atmosphere makes up a substantial fraction of the atmospheric mass within some layer. Non-dilute dynamics can occur for a wide range of condensibles, generically applying near both the inner and the outer edges of the conventional habitable zone and in connection with runaway greenhouse phenomena. It also applies in a wide variety of other planetary circumstances. We first present a number of analytical results developing some key features of non-dilute atmospheres, and then show how some of these features are manifest in simulations with a general circulation model adapted to handle non-dilute atmospheres. We find that non-dilute atmospheres have weak horizontal temperature gradients even for rapidly rotating planets, and that their circulations are largely barotropic. The relative humidity of the condensible component tends towards 100% as the atmosphere becomes more non-dilute, which has important implications for runaway greenhouse thresholds. Non-dilute atmospheres exhibit a number of interesting organized convection features, for which there is not yet any adequate theoretical understanding.

  5. Three dimensional atmospheric dynamics of terrestrial exoplanets over a wide range of orbital and atmospheric parameters

    NASA Astrophysics Data System (ADS)

    Kaspi, Y.; Showman, A. P.

    2014-04-01

    The recent discoveries of terrestrial exoplanets and super Earths extending over a broad range of orbital and physical parameters, suggests that these planets will span a wide range of climatic regimes. Characterization of the atmospheres of warm super Earths has already begun and will be extended to smaller and more distant planets over the coming decade. The habitability of these worlds may be strongly affected by their three-dimensional atmospheric circulation regimes, since the global climate feedbacks that control the inner and outer edges of the habitable zone-including transitions to Snowballlike states and runaway-greenhouse feedbacks-depend on the equator-to-pole temperature differences, pattern of relative humidity, and other aspects of the dynamics. Here, using an idealized moist atmospheric general circulation model (GCM) including a hydrological cycle, we study the dynamical principles governing the atmospheric dynamics on such planets. We show how the planetary rotation rate, planetary mass, surface gravity, heat flux from a parent star and atmospheric mass affect the atmospheric circulation and temperature distribution on such planets. We elucidate the possible climatic regimes and diagnose the mechanisms controlling the formation of atmospheric jet streams, Hadley cells, and the equator-to-pole temperature differences. Finally, we discuss the implications for understanding how the atmospheric circulation influences the global-scale climate feedbacks that control the width of the habitable zone.

  6. Atmospheric dynamics of terrestrial exoplanets over a wide range of orbital and atmospheric parameters

    NASA Astrophysics Data System (ADS)

    Kaspi, Yohai; Showman, Adam

    2014-05-01

    The recent discoveries of terrestrial exoplanets and super Earths extending over a broad range of orbital and physical parameters, suggests that these planets will span a wide range of climatic regimes. Characterization of the atmospheres of warm super Earths has already begun and will be extended to smaller and more distant planets over the coming decade. The habitability of these worlds may be strongly affected by their three-dimensional atmospheric circulation regimes, since the global climate feedbacks that control the inner and outer edges of the habitable zone--including transitions to Snowball-like states and runaway-greenhouse feedbacks--depend on the equator-to-pole temperature differences, pattern of relative humidity, and other aspects of the dynamics. Here, using an idealized moist atmospheric general circulation model (GCM) including a hydrological cycle, we study the dynamical principles governing the atmospheric dynamics on such planets. We show how the planetary rotation rate, planetary mass, surface gravity, heat flux from a parent star, atmospheric mass and optical thickness affect the atmospheric circulation and temperature distribution on such planets. We elucidate the possible climatic regimes and diagnose the mechanisms controlling the formation of atmospheric jet streams, Hadley cells, and the equator-to-pole temperature differences. Finally, we discuss the implications for understanding how the atmospheric circulation influences the global-scale climate feedbacks that control the width of the habitable zone.

  7. Predicting the Atmospheric Composition of Extrasolar Giant Planets

    NASA Technical Reports Server (NTRS)

    Sharp, A. G.; Moses, J. I.; Friedson, A. J.; Fegley, B., Jr.; Marley, M. S.; Lodders, K.

    2004-01-01

    To date, approximately 120 planet-sized objects have been discovered around other stars, mostly through the radial-velocity technique. This technique can provide information about a planet s minimum mass and its orbital period and distance; however, few other planetary data can be obtained at this point in time unless we are fortunate enough to find an extrasolar giant planet that transits its parent star (i.e., the orbit is edge-on as seen from Earth). In that situation, many physical properties of the planet and its parent star can be determined, including some compositional information. Our prospects of directly obtaining spectra from extrasolar planets may improve in the near future, through missions like NASA's Terrestrial Planet Finder. Most of the extrasolar giant planets (EGPs) discovered so far have masses equal to or greater than Jupiter's mass, and roughly 16% have orbital radii less than 0.1 AU - extremely close to the parent star by our own Solar-System standards (note that Mercury is located at a mean distance of 0.39 AU and Jupiter at 5.2 AU from the Sun). Although all EGPs are expected to have hydrogen-dominated atmospheres similar to Jupiter, the orbital distance can strongly affect the planet's temperature, physical, chemical, and spectral properties, and the abundance of minor, detectable atmospheric constituents. Thermochemical equilibrium models can provide good zero-order predictions for the atmospheric composition of EGPs. However, both the composition and spectral properties will depend in large part on disequilibrium processes like photochemistry, chemical kinetics, atmospheric transport, and haze formation. We have developed a photochemical kinetics, radiative transfer, and 1-D vertical transport model to study the atmospheric composition of EGPs. The chemical reaction list contains H-, C-, O-, and N-bearing species and is designed to be valid for atmospheric temperatures ranging from 100-3000 K and pressures up to 50 bar. Here we examine

  8. Nitrogen isotopic composition and density of the Archean atmosphere.

    PubMed

    Marty, Bernard; Zimmermann, Laurent; Pujol, Magali; Burgess, Ray; Philippot, Pascal

    2013-10-04

    Understanding the atmosphere's composition during the Archean eon is fundamental to unraveling ancient environmental conditions. We show from the analysis of nitrogen and argon isotopes in fluid inclusions trapped in 3.0- to 3.5-billion-year-old hydrothermal quartz that the partial pressure of N2 of the Archean atmosphere was lower than 1.1 bar, possibly as low as 0.5 bar, and had a nitrogen isotopic composition comparable to the present-day one. These results imply that dinitrogen did not play a significant role in the thermal budget of the ancient Earth and that the Archean partial pressure of CO2 was probably lower than 0.7 bar.

  9. Paleosols and their relevance to Precambrian atmospheric composition

    PubMed

    Palmer, J A; Phillips, G N; McCarthy, T S

    1989-01-01

    Various paleosols have been reported from within the Witwatersrand and Ventersdorp Supergroups, South Africa. They were studied in an attempt to constrain the amount of oxygen available in the atmosphere during deposition of the gold- and uranium-bearing Witwatersrand conglomerates. The majority of these horizons do not have any physical characteristics of paleosols, and none of them have a chemistry consistent with weathering, suggesting they have been subjected to modification by later alteration processes. A similar chemistry, indicating overprinting of any original soil chemistry, has been reported from paleosols elsewhere (Elliot Lake region, Canada; Hekpoort basalt, South Africa), but it does not appear that significant cognizance has been taken of this fact when using these paleosols to determine the composition of the Precambrian atmosphere. It is concluded here that characteristics previously attributed to Precambrian weathering in an oxygen-deficient atmosphere are better explained by post-burial, hydrothermal alteration along lithological contacts.

  10. Solar-wind interactions - Nature and composition of lunar atmosphere

    NASA Technical Reports Server (NTRS)

    Mukherjee, N. R.

    1975-01-01

    The nature and composition of the lunar atmosphere are examined on the basis of solar-wind interactions, and the nature of the species in the trapped-gas layer is discussed using results of theoretical and experimental investigations. It is shown that the moon has a highly tenuous atmosphere consisting of various species derived from five sources: solar-wind interaction products, cosmic-ray interaction products, effects of meteoritic impacts, planetary degassing, and radioactive-decay products. Atmospheric concentrations are determined for those species derived from solar-wind protons, alpha particles, and oxygen ions. Carbon chemistry is briefly discussed, and difficulties encountered in attempts to determine quantitatively the concentrations of molecular oxygen, atomic oxygen, carbon monoxide, carbon dioxide, and methane are noted. The calculated concentrations are shown to be in good agreement with observations by the Apollo 17 lunar-surface mass spectrometer and orbital UV spectrometer.

  11. Dynamic simulation for distortion image with turbulence atmospheric transmission effects

    NASA Astrophysics Data System (ADS)

    Du, Huijie; Fei, Jindong; Qing, Duzheng; Zhao, Hongming; Yu, Hong; Cheng, Chen

    2013-09-01

    The imaging through atmospheric turbulence is an inevitable problem encountered by infrared imaging sensors working in the turbulence atmospheric environment. Before light-rays enter the window of the imaging sensors, the atmospheric turbulence will randomly interfere with the transmission of the light waves came from the objects, causing the distribution of image intensity values on the focal plane to diffuse, the peak value to decrease, the image to get blurred, and the pixels to deviate, and making image identification very difficult. Owing to the fact of the long processing time and that the atmospheric turbulent flow field is unknown and hard to be described by mathematical models, dynamic simulation for distortion Image with turbulence atmospheric transmission effects is much more difficult and challenging in the world. This paper discusses the dynamic simulation for distortion Image of turbulence atmospheric transmission effect. First of all, with the data and the optical transmission model of the turbulence atmospheric, the ray-tracing method is applied to obtain the propagation path of optical ray which propagates through the high-speed turbulent flow field, and then to calculate the OPD from the reference wave to the reconverted wave front and obtain the point spread function (PSF). Secondly, infrared characteristics models of typical scene were established according to the theory of infrared physics and heat conduction, and then the dynamic infrared image was generated by OpenGL. The last step is to obtain the distortion Image with turbulence atmospheric transmission effects .With the data of atmospheric transmission computation, infrared simulation image of every frame was processed according to the theory of image processing and the real-time image simulation, and then the dynamic distortion simulation images with effects of blurring, jitter and shifting were obtained. Above-mentioned simulation method can provide the theoretical bases for recovering

  12. Fire Influences on Atmospheric Composition, Air Quality, and Climate

    NASA Technical Reports Server (NTRS)

    Voulgarakis, Apostolos; Field, Robert D.

    2015-01-01

    Fires impact atmospheric composition through their emissions, which range from long-lived gases to short-lived gases and aerosols. Effects are typically larger in the tropics and boreal regions but can also be substantial in highly populated areas in the northern mid-latitudes. In all regions, fire can impact air quality and health. Similarly, its effect on large-scale atmospheric processes, including regional and global atmospheric chemistry and climate forcing, can be substantial, but this remains largely unexplored. The impacts are primarily realised in the boundary layer and lower free troposphere but can also be noticeable in upper troposphere/lower stratosphere (UT/LS) region, for the most intense fires. In this review, we summarise the recent literature on findings related to fire impact on atmospheric composition, air quality and climate. We explore both observational and modelling approaches and present information on key regions and on the globe as a whole. We also discuss the current and future directions in this area of research, focusing on the major advances in emission estimates, the emerging efforts to include fire as a component in Earth system modelling and the use of modelling to assess health impacts of fire emissions.

  13. Dynamic Data-Driven Event Reconstruction for Atmospheric Releases

    SciTech Connect

    Kosovic, B; Belles, R; Chow, F K; Monache, L D; Dyer, K; Glascoe, L; Hanley, W; Johannesson, G; Larsen, S; Loosmore, G; Lundquist, J K; Mirin, A; Neuman, S; Nitao, J; Serban, R; Sugiyama, G; Aines, R

    2007-02-22

    Accidental or terrorist releases of hazardous materials into the atmosphere can impact large populations and cause significant loss of life or property damage. Plume predictions have been shown to be extremely valuable in guiding an effective and timely response. The two greatest sources of uncertainty in the prediction of the consequences of hazardous atmospheric releases result from poorly characterized source terms and lack of knowledge about the state of the atmosphere as reflected in the available meteorological data. In this report, we discuss the development of a new event reconstruction methodology that provides probabilistic source term estimates from field measurement data for both accidental and clandestine releases. Accurate plume dispersion prediction requires the following questions to be answered: What was released? When was it released? How much material was released? Where was it released? We have developed a dynamic data-driven event reconstruction capability which couples data and predictive models through Bayesian inference to obtain a solution to this inverse problem. The solution consists of a probability distribution of unknown source term parameters. For consequence assessment, we then use this probability distribution to construct a ''''composite'' forward plume prediction which accounts for the uncertainties in the source term. Since in most cases of practical significance it is impossible to find a closed form solution, Bayesian inference is accomplished by utilizing stochastic sampling methods. This approach takes into consideration both measurement and forward model errors and thus incorporates all the sources of uncertainty in the solution to the inverse problem. Stochastic sampling methods have the additional advantage of being suitable for problems characterized by a non-Gaussian distribution of source term parameters and for cases in which the underlying dynamical system is non-linear. We initially developed a Markov Chain Monte

  14. Constraining hot Jupiter’s atmospheric structure and dynamics through Doppler shifted emission spectra

    NASA Astrophysics Data System (ADS)

    Zhang, Jisheng; Kempton, Eliza; Rauscher, Emily

    2017-01-01

    In recent years, astronomers have begun successfully observing the atmospheres of extrasolar planets using ground-based telescopes equipped with spectrographs capable of observing at high spectral resolution (R~105). Such studies are capable of diagnosing the atmospheric structure, composition, and dynamics (winds and rotation) of both transiting and non-transiting exoplanets. However, few studies have examined how the 3-D atmospheric dynamics could alter the emitted light of hot Jupiters at such high spectral resolution. Here, we present a model to explore such influence on the hot Jupiters’ thermal emission spectra. Our aim is to investigate the extent to which the effects of 3-D atmospheric dynamics are imprinted on planet-averaged thermal emission spectra. We couple together a 3-D general circulation model of hot Jupiter atmospheric dynamics (Rauscher & Menou, 2012) with a radiative transfer solver to predict the planet’s disk-integrated emission spectrum as a function of its orbital phase. For the first time, we self-consistently include the effects of the line-of-sight atmospheric motions (resulting from winds and rotation) in the calculation to produce Doppler-shifted spectral line profiles that result from the atmospheric dynamics. We focus our study on three benchmark hot Jupiters, HD 189733b, HD 209458b, and WASP-43b which have been the focus of previous detailed observational studies. We find that the high-resolution Doppler shifted thermal emission spectra can be used to diagnose key properties of the dynamical atmosphere - the planet’s longitudinal temperature and wind structure, and its rotation rate.

  15. Dynamics of Undisturbed Midlatitude Atmospheric Electricity: From Observations to Scaling

    NASA Astrophysics Data System (ADS)

    Anisimov, S. V.; Afinogenov, K. V.; Shikhova, N. M.

    2014-04-01

    Long-term dynamics of the electric field of the midlatitude near-surface atmosphere in a wide range of temporal scales is analyzed according to multiyear observatory and seasonal field observations. It is found that the daily dynamics of the aeroelectric field at mid-latitudes most authentically repeats a diurnal variation for the winter months. It is stated that short-period pulsations of the electric field have a self-similar power-law spectrum. Spatio-temporal scales of the self-similarity interval are estimated and the nature of the generalized diffusive process of the aeroelectric pulsation generation is defined. Characteristics of the turbulent ΔE pulsations are analyzed. Estimates of interrelation between the dynamic (fractal dimensions, intermittency indices) and power (degrees of spectral index and structure function) ΔE characteristics are obtained. Mutual correlations between atmospheric electric field variations, vertical atmospheric electrical current density, space charge density, and atmospheric electrical conductivity are studied. It is shown that variations of the light atmospheric ion number density and space charge density are related with variations of the Radon-222 emanations. Spectral analysis of the space charge density variations is carried out. It is shown that the electrodynamic state of the surface atmosphere depends on the convective state of the atmospheric boundary layer.

  16. Lidar application to middle atmospheric dynamics

    NASA Astrophysics Data System (ADS)

    Ramesh, K.; Sridharan, S.

    2016-05-01

    LIDAR (LIght Detection And Ranging) is an optical remote sensing technique which can be used to probe middle atmosphere (stratosphere & mesosphere) from where RADAR (RAdio Detection And Ranging) system fails to get scattering. The Mie and Rayleigh lidar system installed at National Atmospheric Research Laboratory (NARL), Gadanki (13.5°N, 79.2°E) has been operating at 532 nm green laser with increased energy of 600 mJ/pulse and pulse repletion frequency of 50 Hz since 2007. From the Rayleigh lidar observations, vertical profiles of atmospheric density and temperature can be obtained above 25-30 km (where the aerosols are almost negligible) at high spatial and temporal resolutions. The temperature profiles often show mesospheric inversion layers (MILs), the causative mechanisms of which are yet to be understood. In the present study, the improved performance of the lidar system is demonstrated by showing the height profile of temperature and its error obtained with the high power laser ( 12 W per pulse) on 20 January 2007 when compared to the same obtained using the low power laser ( 5 W per pulse) on 05 February 2007 over Gadanki. The temperature errors observed at 80 km are 3.5 K, 18 K with high and low power lasers respectively. A large MIL has been observed on 20 January 2007 above 78 km with amplitude of 31 K from the lidar temperature operated with high power laser. The dominant gravity wave (GW) period and vertical wavelengths are found to be T 66 min and λz 6.4 km in the inversion region. The wave saturation ratio and eddy diffusion coefficient due to the GW breaking are calculated and it is found that the wave gets saturated at 84-85 km and the eddy diffusion coefficient increases from 25 m2/sec above the inversion region ( 83 km). This result suggests that the occurrence of this large MIL event is probably due to gravity wave breaking.

  17. Atmospheric Dynamics of Terrestrial Exoplanets Over a Wide Range of Orbital and Atmospheric Parameters

    NASA Astrophysics Data System (ADS)

    Kaspi, Yohai; Showman, Adam P.

    2014-11-01

    Since the mid-1990s, nearly 1800 exoplanets have been discovered around other stars. Exoplanet discovery and characterization began with giant planets, but as the observational techniques are advancing the emphasis is gradually shifting to smaller worlds. The recent discoveries of terrestrial exoplanets and super Earths extending over a broad range of orbital and physical parameters suggests that these planets will span a wide range of climatic regimes. Characterization of the atmospheres of warm super Earths has already begun and will be extended to smaller and more distant planets over the coming decade. The habitability of these worlds may be strongly affected by their three-dimensional atmospheric circulation regimes, since the global climate feedbacks that control the inner and outer edges of the habitable zone---including transitions to Snowball-like states and runaway-greenhouse feedbacks---depend on the equator-to-pole temperature differences, pattern of relative humidity, and other aspects of the dynamics. Here, using an idealized moist atmospheric general circulation model (GCM) including a hydrological cycle, we discuss the dynamical principles governing the atmospheric dynamics on such planets. We show how the planetary rotation rate, planetary mass, surface gravity, heat flux from a parent star, optical thickness and atmospheric mass affect the atmospheric circulation and temperature distribution on such planets. Our simulations demonstrate that equator-to-pole temperature differences, meridional heat transport rates, structure and strength of the winds, and the hydrological cycle vary strongly with these parameters, implying that the sensitivity of the planet to global climate feedbacks will depend significantly on the atmospheric circulation. We elucidate the possible climatic regimes and diagnose the mechanisms controlling the formation of atmospheric jet stream, Hadley and Ferrel cells and latitudinal temperature differences. Finally, we will

  18. Gravity-Wave Dynamics in the Atmosphere

    DTIC Science & Technology

    2010-02-01

    of wave-induced downslope winds. Journal of the Atmospheric Sciences, 32(2):320–339, 1975. [12] P. K. Kundu and I. M. Cohen. Fluid Mechanics . Elsevier...Wave Beams and Local Generation of Solitary Waves in the Ocean Thermocline”, Journal of Fluid Mechanics , 593, 297-313 (2007) Akylas, T. R. & Druecke...334–348, 1992. [4] T. H. Bell. Lee waves in stratified flows with simple harmonic time-dependence. Journal of Fluid Mechanics , 67(FEB25):705–722

  19. Chemistry of atmospheric nucleation: on the recent advances on precursor characterization and atmospheric cluster composition in connection with atmospheric new particle formation.

    PubMed

    Kulmala, M; Petäjä, T; Ehn, M; Thornton, J; Sipilä, M; Worsnop, D R; Kerminen, V-M

    2014-01-01

    The recent development in measurement techniques and theoretical understanding has enabled us to study atmospheric vapor, cluster and nanoparticle concentrations, dynamics, and their connection to atmospheric nucleation. Here we present a summary of the chemistry of atmospheric clustering, growing nanoparticles, and their precursors. In this work, we focus particularly on atmospheric gas-to-particle conversion and recent progress in its understanding.

  20. Sharing is Winning: Cooperative Learning about Atmospheric Composition Change

    NASA Astrophysics Data System (ADS)

    Schuepbach, E.

    2010-09-01

    This contribution presents evolving good practice in disseminating the body of know-how, skills and competencies within the networked community of atmospheric scientists as established in ACCENT. The promotion of early-career scientists, and encouraging the next generation to move into the field were among the key issues addressed by the "Training and Education" programme in the European Network of Excellence in Atmospheric Composition Change (ACCENT). Dissemination avenues include a virtual knowledge train carrying the wealth of high-quality scientific learning material developed with experts involved in the ACCENT network. Learning opportunities on current research in atmospheric composition change in Europe were also created during face-to-face training workshops. Real-life examples of pressing air quality issues were addressed in meetings with stakeholder groups that offered opportunities for mutual learning in inspiring partnerships. In order to increase the expertise in atmospheric composition change across Europe, activities were organized with the general public (e.g., Café Scientifique), where the participating early-career scientists were confronted with questions from lay people. For interested teachers, didactic translations of compact overviews on air quality science topics developed in ACCENT offer links with the typical European science curriculum and go beyond school book content. Some of the educational events, methods and tools are described in a booklet published in 2009 ("We Care for Clean Air!", ISBN 978-88-95665-01-6). The electronic version and all training material can be downloaded from www.accent-network.org/portal/education - a valuable resource for teachers and learners around the globe.

  1. The Middle Atmosphere Program: A special project for the Antarctic Middle Atmosphere (AMA)

    NASA Technical Reports Server (NTRS)

    Hirasawa, T.

    1982-01-01

    Areas of concern are: dynamics, structure, and atmospheric composition of the middle atmosphere in Antarctica; particle precipitation and interaction of the middle atmosphere with the lower ionosphere; atmospheric pollution; and the difference between the northern and southern polar middle atmosphere.

  2. The Middle Atmosphere Program: A special project for the Antarctic Middle Atmosphere (AMA)

    NASA Astrophysics Data System (ADS)

    Hirasawa, T.

    1982-04-01

    Areas of concern are: dynamics, structure, and atmospheric composition of the middle atmosphere in Antarctica; particle precipitation and interaction of the middle atmosphere with the lower ionosphere; atmospheric pollution; and the difference between the northern and southern polar middle atmosphere.

  3. Building a "big picture" of planetary atmospheres dynamics

    NASA Astrophysics Data System (ADS)

    Read, Peter; Wang, Yixiong

    and explore relatively simple parameter spaces for atmospheric circulation systems, along similar lines to what is commonly done in the laboratory, without the need to compute many of the details specific to individual planetary composition, topography etc. Trends observed in such studies indicate that a common theoretical framework can account for many of the basic differences and similarities between the terrestrial planets in the Solar System, although this approach is still in its infancy. Such an approach can even enable simple predictions to be made of the style and intensity of circulation for planets (e.g. around other stars) yet to be discovered. Future work along similar lines, however, will need to take into account a wider range of possibilities than has been studied systematically hitherto, including the full range of planetary obliquity and seasonal variations, ratios of dynamical and radiative timescales, diurnal cycles and tidally-locked states. [1] R. Hide and P. J. Mason. Adv. in Phys., 24:47-99, 1975 [2] Wordsworth, R. D., Read, P. L. Yamazaki, H. Y. (2008) Phys. Fluids, 20, 126602

  4. Application of atmospheric pressure plasma in polymer and composite adhesion

    NASA Astrophysics Data System (ADS)

    Yu, Hang

    An atmospheric pressure helium and oxygen plasma was used to investigate surface activation and bonding in polymer composites. This device was operated by passing 1.0-3.0 vol% of oxygen in helium through a pair of parallel plate metal electrodes powered by 13.56 or 27.12 MHz radio frequency power. The gases were partially ionized between the capacitors where plasma was generated. The reactive species in the plasma were carried downstream by the gas flow to treat the substrate surface. The temperature of the plasm gas reaching the surface of the substrate did not exceed 150 °C, which makes it suitable for polymer processing. The reactive species in the plasma downstream includes ~ 1016-1017 cm-3 atomic oxygen, ~ 1015 cm-3 ozone molecule, and ~ 10 16 cm-3 metastable oxygen molecule (O2 1Deltag). The substrates were treated at 2-5 mm distance from the exit of the plasma. Surface properties of the substrates were characterized using water contact angle (WCA), atomic force microscopy (AFM), infrared spectroscopy (IR), and X-ray photoelectron spectroscopy (XPS). Subsequently, the plasma treated samples were bonded adhesively or fabricated into composites. The increase in mechanical strength was correlated to changes in the material composition and structure after plasma treatment. The work presented hereafter establishes atmospheric pressure plasma as an effective method to activate and to clean the surfaces of polymers and composites for bonding. This application can be further expanded to the activation of carbon fibers for better fiber-resin interactions during the fabrication of composites. Treating electronic grade FR-4 and polyimide with the He/O2 plasma for a few seconds changed the substrate surface from hydrophobic to hydrophilic, which allowed complete wetting of the surface by epoxy in underfill applications. Characterization of the surface by X-ray photoelectron spectroscopy shows formation of oxygenated functional groups, including hydroxyl, carbonyl, and

  5. ATMOSPHERIC RETRIEVAL FOR SUPER-EARTHS: UNIQUELY CONSTRAINING THE ATMOSPHERIC COMPOSITION WITH TRANSMISSION SPECTROSCOPY

    SciTech Connect

    Benneke, Bjoern; Seager, Sara

    2012-07-10

    We present a retrieval method based on Bayesian analysis to infer the atmospheric compositions and surface or cloud-top pressures from transmission spectra of exoplanets with general compositions. In this study, we identify what can unambiguously be determined about the atmospheres of exoplanets from their transmission spectra by applying the retrieval method to synthetic observations of the super-Earth GJ 1214b. Our approach to inferring constraints on atmospheric parameters is to compute their joint and marginal posterior probability distributions using the Markov Chain Monte Carlo technique in a parallel tempering scheme. A new atmospheric parameterization is introduced that is applicable to general atmospheres in which the main constituent is not known a priori and clouds may be present. Our main finding is that a unique constraint of the mixing ratios of the absorbers and two spectrally inactive gases (such as N{sub 2} and primordial H{sub 2}+ He) is possible if the observations are sufficient to quantify both (1) the broadband transit depths in at least one absorption feature for each absorber and (2) the slope and strength of the molecular Rayleigh scattering signature. A second finding is that the surface pressure or cloud-top pressure can be quantified if a surface or cloud deck is present at low optical depth. A third finding is that the mean molecular mass can be constrained by measuring either the Rayleigh scattering slope or the shapes of the absorption features, thus enabling one to distinguish between cloudy hydrogen-rich atmospheres and high mean molecular mass atmospheres. We conclude, however, that without the signature of molecular Rayleigh scattering-even with robustly detected infrared absorption features (>10{sigma})-there is no reliable way to tell from the transmission spectrum whether the absorber is a main constituent of the atmosphere or just a minor species with a mixing ratio of X{sub abs} < 0.1%. The retrieval method leads us to a

  6. Vesper - Venus Chemistry and Dynamics Orbiter - A NASA Discovery Mission Proposal: Submillimeter Investigation of Atmospheric Chemistry and Dynamics

    NASA Technical Reports Server (NTRS)

    Chin, Gordon

    2011-01-01

    Vesper conducts a focused investigation of the chemistry and dynamics of the middle atmosphere of our sister planet- from the base of the global cloud cover to the lower thermosphere. The middle atmosphere controls the stability of the Venus climate system. Vesper determines what processes maintain the atmospheric chemical stability, cause observed variability of chemical composition, control the escape of water, and drive the extreme super-rotation. The Vesper science investigation provides a unique perspective on the Earth environment due to the similarities in the middle atmosphere processes of both Venus and the Earth. Understanding key distinctions and similarities between Venus and Earth will increase our knowledge of how terrestrial planets evolve along different paths from nearly identical initial conditions.

  7. Composition and evolution of the atmosphere of Venus

    NASA Technical Reports Server (NTRS)

    Donahue, Thomas (Principal Investigator)

    1996-01-01

    The contract year started by analyzing Jovian atmospheric data acquired by the Galileo Probe Mass Spectrometer (GPMS). Two Venus hydrogen projects got underway as well. The first study strives to understand how to reconcile the standard treatment of the evolution of the H2O and HDO resevoirs on Venus over 4.5 Gyr in the presence of H and D escape and injection by comets. The second study is calculating the charge exchange contribution to hydrogen loss rates, using realistic models for exospheric H, H(+), D, D(+), and ion temperature from PV data. This report includes the following papers as attachments and supporting data: 'The Galileo Probe Mass Spectrometer: Composition of Jupiter's Atmosphere'; 'Chemical Composition Measurements of the Atmosphere of Jupiter with the Galileo Probe Mass Spectrometer'; 'Ion/Neutral Escape of Hydrogen and Deuterium: Evolution of Water'; 'Hydrogen and Deuterium in the Thermosphere of Venus: Solar Cycle Variations and Escape'; and 'Solar Cycle Variations in H(+) and D(+) Densities in the Venus Ionosphere: Implications for Escape'.

  8. Atmosphere composition monitor for space station and advanced missions application

    SciTech Connect

    Wynveen, R.A.; Powell, F.T.

    1987-01-01

    Long-term human occupation of extraterrestrial locations may soon become a reality. The National Aeronautics and Space Administration (NASA) has recently completed the definition and preliminary design of the low earth orbit (LEO) space station. They are now currently moving into the detailed design and fabrication phase of this space station and are also beginning to analyze the requirements of several future missions that have been identified. These missions include, for example, Lunar and Mars sorties, outposts, bases, and settlements. A requirement of both the LEO space station and future missions are environmental control and life support systems (ECLSS), which provide a comfortable environment for humans to live and work. The ECLSS consists of several major systems, including atmosphere revitalization system (ARS), atmosphere pressure and composition control system, temperature and humidity control system, water reclamation system, and waste management system. Each of these major systems is broken down into subsystems, assemblies, units, and instruments. Many requirements and design drivers are different for the ECLSS of the LEO space station and the identified advanced missions (e.g., longer mission duration). This paper discusses one of the ARS assemblies, the atmosphere composition monitor assembly (ACMA), being developed for the LEO space station and addresses differences that will exist for the ACMA of future missions.

  9. Atmospheric chemical composition of the peculiar carbon giant TU Gem

    NASA Astrophysics Data System (ADS)

    Yakovina, L. A.; Polinovskii, G. A.; Pavlenko, Ya. V.; Kuznetsov, M. K.

    2017-01-01

    The evolutionary status of the bright peculiar carbon giant TU Gemis fairly uncertain. The possibility that this is aCH star—aGalactic halo star with characteristic chemical-composition anomalies—is considered. Unfortunately, data on the atmospheric chemical composition of TUGem are relatively few and are ambiguous. The results of an analysis of a moderate-resolution optical and near-infrared spectrum of TU Gem obtained on the 2-m telescope of Terskol Peak Observatory (Northern Caucasus) is presented. The atmospheric parameters of TU Gem T eff = 3100 K, C/O = 1.10, and [N/Fe] = 0.0 for the derived metallicity [Fe/H] = 0.0 are taken from [1]. The abundances of Na, Mg, Ca, Ti, and Cr are estimated to be normal or slightly enhanced, and the lithium abundance is log N(Li) = +0.1. The abundances of s-process elements are substantially enhanced in the atmosphere of TU Gem, namely, [s/Fe] ≈ 2, for both light and heavy s-process elements. The range of uncertainty in [Fe/H] is 0.0-0.3, and the uncertainties in other estimates are Δ[M/Fe]≈ ±0.3 and Δ[ s/Fe] = ±0.5. The results show that TU Gem is an anomalous carbon giant, but not a CH star.

  10. Satellite Observations for Detecting and Tracking Changes in Atmospheric Composition

    NASA Technical Reports Server (NTRS)

    Neil, Doreen O.; Kondragunbta, Shobha; Osterman, Gregory; Pickering, Kenneth; Pinder, Robert W.; Prados, Ana I.; Szykman, James

    2009-01-01

    The satellite observations provide constraints on detailed atmospheric modeling, including emissions inventories, indications of transport, harmonized data over vast areas suitable for trends analysis, and a link between spatial scales ranging from local to global, and temporal scales from diurnal to interannual. 1 The National Oceanic and Atmospheric Administration's (NOAA) long-term commitments help provide these observations in cooperation with international meteorological organizations. NASA s long-term commitments will advance scientifically important observations as part of its Earth Science Program, and will assist the transition of the science measurements to applied analyses through the Applied Science Program. Both NASA and NOAA have begun to provide near realtime data and tools to visualize and analyze satellite data,2 while maintaining data quality, validation, and standards. Consequently, decision-makers can expect satellite data services to support air quality decision making now and in the future. The international scientific community's Integrated Global Atmosphere Chemistry Observation System Report3 outlined a plan for ground-based, airborne and satellite measurements and models to integrate the observations into a four-dimensional representation of the atmosphere (space and time) to support assessment and policy information needs. This plan is being carried out under the Global Earth Observation System of Systems (GEOSS). Demonstrations of such an integrated capability4 provide new understanding of the changing atmosphere and link policy decisions to benefits for society. In this article, we highlight the use of satellite data to constrain biomass burning emissions, to assess oxides of nitrogen (NO(x)) emission reductions, and to contribute to state implementation plans, as examples of the use of satellite observations for detecting and tracking changes in atmospheric composition.

  11. Atmospheric Dynamics of Terrestrial Exoplanets over a Wide Range of Orbital and Atmospheric Parameters

    NASA Astrophysics Data System (ADS)

    Kaspi, Yohai; Showman, Adam P.

    2015-05-01

    The recent discoveries of terrestrial exoplanets and super-Earths extending over a broad range of orbital and physical parameters suggest that these planets will span a wide range of climatic regimes. Characterization of the atmospheres of warm super-Earths has already begun and will be extended to smaller and more distant planets over the coming decade. The habitability of these worlds may be strongly affected by their three-dimensional atmospheric circulation regimes, since the global climate feedbacks that control the inner and outer edges of the habitable zone—including transitions to Snowball-like states and runaway-greenhouse feedbacks—depend on the equator-to-pole temperature differences, patterns of relative humidity, and other aspects of the dynamics. Here, using an idealized moist atmospheric general circulation model including a hydrological cycle, we study the dynamical principles governing the atmospheric dynamics on such planets. We show how the planetary rotation rate, stellar flux, atmospheric mass, surface gravity, optical thickness, and planetary radius affect the atmospheric circulation and temperature distribution on such planets. Our simulations demonstrate that equator-to-pole temperature differences, meridional heat transport rates, structure and strength of the winds, and the hydrological cycle vary strongly with these parameters, implying that the sensitivity of the planet to global climate feedbacks will depend significantly on the atmospheric circulation. We elucidate the possible climatic regimes and diagnose the mechanisms controlling the formation of atmospheric jet streams, Hadley and Ferrel cells, and latitudinal temperature differences. Finally, we discuss the implications for understanding how the atmospheric circulation influences the global climate.

  12. ATMOSPHERIC DYNAMICS OF TERRESTRIAL EXOPLANETS OVER A WIDE RANGE OF ORBITAL AND ATMOSPHERIC PARAMETERS

    SciTech Connect

    Kaspi, Yohai; Showman, Adam P.

    2015-05-01

    The recent discoveries of terrestrial exoplanets and super-Earths extending over a broad range of orbital and physical parameters suggest that these planets will span a wide range of climatic regimes. Characterization of the atmospheres of warm super-Earths has already begun and will be extended to smaller and more distant planets over the coming decade. The habitability of these worlds may be strongly affected by their three-dimensional atmospheric circulation regimes, since the global climate feedbacks that control the inner and outer edges of the habitable zone—including transitions to Snowball-like states and runaway-greenhouse feedbacks—depend on the equator-to-pole temperature differences, patterns of relative humidity, and other aspects of the dynamics. Here, using an idealized moist atmospheric general circulation model including a hydrological cycle, we study the dynamical principles governing the atmospheric dynamics on such planets. We show how the planetary rotation rate, stellar flux, atmospheric mass, surface gravity, optical thickness, and planetary radius affect the atmospheric circulation and temperature distribution on such planets. Our simulations demonstrate that equator-to-pole temperature differences, meridional heat transport rates, structure and strength of the winds, and the hydrological cycle vary strongly with these parameters, implying that the sensitivity of the planet to global climate feedbacks will depend significantly on the atmospheric circulation. We elucidate the possible climatic regimes and diagnose the mechanisms controlling the formation of atmospheric jet streams, Hadley and Ferrel cells, and latitudinal temperature differences. Finally, we discuss the implications for understanding how the atmospheric circulation influences the global climate.

  13. Lidar Measurements of Atmospheric Dynamics over High Mountainous Terrain

    NASA Astrophysics Data System (ADS)

    Peshev, Zahary Y.; Deleva, Atanaska D.; Dreischuh, Tanja N.; Stoyanov, Dimitar V.

    2010-01-01

    Results of lidar observations on the dynamics of atmospheric layers over the ridge and northeast slope of Vitosha Mountain situated close to Sofia, Bulgaria, are reported and compared with results for layers over surrounding plain and urban zones. Measurements are carried out at 1064 nm wavelength with a lidar range resolution of 15 m, by using one of the aerosol channels of a combined Raman-aerosol lidar based on a powerful Nd:YAG laser. Two cases of distinctly different weather conditions are studied. The mountainous area, situated from 6 km to 12 km away from the lidar station, is scanned reiteratively within 7°-9° slope-angle range. Multiple series of lidar profiles are registered with average time of 2-5 s. Lidar signals are then range corrected and processed statistically. Normalized standard deviation is used as a characteristic of the atmospheric dynamics. The spatial-temporal evolution of atmospheric density fluctuations is shown on colormap plots. Intensive air dynamics over the mountain is revealed, exceeding considerably the one over the plain zone. Peculiarities of the dynamics in the investigated atmospheric domains are discussed. Results obtained show that Vitosha Mountain strongly affects variations of the atmospheric density and stability over large areas.

  14. Probabilistic Dynamic Buckling of Smart Composite Shells

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.; Abumeri, Galib H.

    2007-01-01

    A computational simulation method is presented to evaluate the deterministic and nondeterministic dynamic buckling of smart composite shells. The combined use of intraply hybrid composite mechanics, finite element computer codes, and probabilistic analysis enable the effective assessment of the dynamic buckling load of smart composite shells. A universal plot is generated to estimate the dynamic buckling load of composite shells at various load rates and probabilities. The shell structure is also evaluated with smart fibers embedded in the plies right next to the outer plies. The results show that, on the average, the use of smart fibers improved the shell buckling resistance by about 10% at different probabilities and delayed the buckling occurrence time. The probabilistic sensitivities results indicate that uncertainties in the fiber volume ratio and ply thickness have major effects on the buckling load while uncertainties in the electric field strength and smart material volume fraction have moderate effects. For the specific shell considered in this evaluation, the use of smart composite material is not recommended because the shell buckling resistance can be improved by simply re-arranging the orientation of the outer plies, as shown in the dynamic buckling analysis results presented in this report.

  15. Probabilistic Dynamic Buckling of Smart Composite Shells

    NASA Technical Reports Server (NTRS)

    Abumeri, Galib H.; Chamis, Christos C.

    2003-01-01

    A computational simulation method is presented to evaluate the deterministic and nondeterministic dynamic buckling of smart composite shells. The combined use of composite mechanics, finite element computer codes, and probabilistic analysis enable the effective assessment of the dynamic buckling load of smart composite shells. A universal plot is generated to estimate the dynamic buckling load of composite shells at various load rates and probabilities. The shell structure is also evaluated with smart fibers embedded in the plies right below the outer plies. The results show that, on the average, the use of smart fibers improved the shell buckling resistance by about 10 percent at different probabilities and delayed the buckling occurrence time. The probabilistic sensitivities results indicate that uncertainties in the fiber volume ratio and ply thickness have major effects on the buckling load while uncertainties in the electric field strength and smart material volume fraction have moderate effects. For the specific shell considered in this evaluation, the use of smart composite material is not recommended because the shell buckling resistance can be improved by simply re-arranging the orientation of the outer plies, as shown in the dynamic buckling analysis results presented in this report.

  16. Relation between isotopic composition of precipitation and atmospheric circulation patterns

    NASA Astrophysics Data System (ADS)

    Brenčič, Mihael; Kononova, Nina K.; Vreča, Polona

    2015-10-01

    Precipitation generating processes depend on atmospheric circulation patterns and consequently it is expected that its water stable isotopic composition of hydrogen and oxygen is related to them. Precipitation generated at similar atmospheric circulation patterns should have similar empirical distribution of δ2H and δ18O values. Mathematical model based on the linear combination of δ2H and δ18O values and on precipitation amount weighted average related to elementary air circulation mechanisms - ECM is proposed. The model enables estimation of average δ2H and δ18O values and their standard deviation for the precipitation generated at distinctive atmospheric circulation patterns. Approach in which atmospheric circulation patterns were classified as ECM based on the Dzerdzeevskii classification was applied. Application of the model is illustrated on the long term precipitation record from Ljubljana GNIP station Slovenia. Estimated values of the parameters for empirical distributions of δ2H and δ18O of each ECM subtype have shown that calculated estimates are reasonable. Further applications of the proposed model enable new insight into the understanding of isotopes spatial and temporal distribution in precipitation important also for better understanding of climate proxies.

  17. Atmospheric composition and climate on the early Earth.

    PubMed

    Kasting, James F; Howard, M Tazewell

    2006-10-29

    Oxygen isotope data from ancient sedimentary rocks appear to suggest that the early Earth was significantly warmer than today, with estimates of surface temperatures between 45 and 85 degrees C. We argue, following others, that this interpretation is incorrect-the same data can be explained via a change in isotopic composition of seawater with time. These changes in the isotopic composition could result from an increase in mean depth of the mid-ocean ridges caused by a decrease in geothermal heat flow with time. All this implies that the early Earth was warm, not hot.A more temperate early Earth is also easier to reconcile with the long-term glacial record. However, what triggered these early glaciations is still under debate. The Paleoproterozoic glaciations at approximately 2.4Ga were probably caused by the rise of atmospheric O2 and a concomitant decrease in greenhouse warming by CH4. Glaciation might have occurred in the Mid-Archaean as well, at approximately 2.9Ga, perhaps as a consequence of anti-greenhouse cooling by hydrocarbon haze. Both glaciations are linked to decreases in the magnitude of mass-independent sulphur isotope fractionation in ancient rocks. Studying both the oxygen and sulphur isotopic records has thus proved useful in probing the composition of the early atmosphere.

  18. Atmospheric composition and climate on the early Earth

    PubMed Central

    Kasting, James F; Howard, M. Tazewell

    2006-01-01

    Oxygen isotope data from ancient sedimentary rocks appear to suggest that the early Earth was significantly warmer than today, with estimates of surface temperatures between 45 and 85°C. We argue, following others, that this interpretation is incorrect—the same data can be explained via a change in isotopic composition of seawater with time. These changes in the isotopic composition could result from an increase in mean depth of the mid-ocean ridges caused by a decrease in geothermal heat flow with time. All this implies that the early Earth was warm, not hot. A more temperate early Earth is also easier to reconcile with the long-term glacial record. However, what triggered these early glaciations is still under debate. The Paleoproterozoic glaciations at approximately 2.4 Ga were probably caused by the rise of atmospheric O2 and a concomitant decrease in greenhouse warming by CH4. Glaciation might have occurred in the Mid-Archaean as well, at approximately 2.9 Ga, perhaps as a consequence of anti-greenhouse cooling by hydrocarbon haze. Both glaciations are linked to decreases in the magnitude of mass-independent sulphur isotope fractionation in ancient rocks. Studying both the oxygen and sulphur isotopic records has thus proved useful in probing the composition of the early atmosphere. PMID:17008214

  19. A compositing approach for preserving signifigant features in atmospheric profiles

    SciTech Connect

    Brown, R. )

    1993-03-01

    Composite profiles of thermodynamic and kinematic variables are prepared to represent the characteristics of the environment within which a particular atmospheric phenomenon occurs. During the averaging process, it is desirable to retain the dominant features and associated gradients found in the individual profiles so that representative values of quantities such as flux parameters, energy budgets, convective available ptoential energy, and various stability indices can be computed from the composite profiles. The conventional compositing approach, where averages are computed at common heights, reduces or even smooths out a significant feature when the height and vertical extent of the feature differ from one individual file to the next. To retain a desirable feature in the composite profile, it is necessary to compute averages at the heights where the feature occurs and to compute the average height of the feature itself. As an example ot the capabilities of this scaling or feature-preserving approach, the technique was applied to a set of 33 hodographs from supercell thunderstorm environments as documented in the literature. The feature-preserving technique retained realistic wind-shear values, including a midaltitude minimum-shear layer that disappeared when the conventional compositing technique was used. 44 refs., 5 figs., 1 tab.

  20. [Dynamic control of the atmospheric parameters of spacecraft].

    PubMed

    Breslav, I S; Salazkin, V N

    1977-01-01

    On the basis of experimental data a mathematical model of relationships between physiological parameters, oxygen content in the atmosphere and exercises has been developed. Using the model, it has been demonstrated that circulation and respiration reactions to exercises can be optimized by increasing the partial pressure of oxygen as related to the exercise level. A probable law of the dynamic and physiologically optimal control of the oxygen content in the space cabin atmosphere has been advanced. In cases of an uncontrolled decrease of PO2 the oxygen supply of crewmembers can be optimized by the dynamic control of the ambient CO2 content.

  1. Lower atmospheric composition of Jupiter from Voyager infrared measurements

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.

    1984-01-01

    The observed spectrum of Jovian atmosphere exhibits spectral features of H2, CH4, C2H6, NH3, H2O, GeH4 and CH3D. Analytical programs were developed for radiative transfer calculations and for retrieval of lower atmospheric composition of Jupiter from the observed infrared spectrum. The program models developed are based line by line transmittance calculations with appropriate convolution of the instrument function. The constituent inversion programs were evaluated for accuracy by analyzing synthetic data for retrievals of NH3 profiles. The inversion programs were employed for retrieval of NH3 profiles from the Voyager infared data with results generally in agreement with the accepted values.

  2. Measurement of atmospheric neutrino composition with the IMB-3 detector

    SciTech Connect

    Casper, D.; Becker-Szendy, R.; Bratton, C.B.; Cady, D.R.; Claus, R.; Dye, S.T.; Gajewski, W.; Goldhaber, M.; Haines, T.J.; Halverson, P.G.; Jones, T.W.; Kielczewska, D.; Kropp, W.R.; Learned, J.G.; LoSecco, J.M.; McGrew, C.; Matsuno, S.; Matthews, J.; Mudan, M.S.; Price, L.; Reines, F.; Schultz, J.; Sinclair, D.; Sobel, H.W.; Stone, J.L.; Sulak, L.R.; Svoboda, R.; Thornton, G.; van der Velde, J.C. The University of Michigan, Ann Arbor, Michigan 48109 Brookhaven National Laboratory, Upton, New York 11973 Boston University, Boston, Massachusetts 02215 The University of Hawaii, Honolulu, Hawaii 96822 University College, London, WC1E F6BT, United Kingdom Warsaw University, Warsaw, Poland Cleveland State University, Cleveland, Ohio 44115 The University of Notre Dame, Notre Dame, Indiana 46556 Lousiana State University, Baton Rouge, Lousisiana 70803 The University of Maryland, College Park, Maryland 20742)

    1991-05-20

    The atmospheric neutrino flux is measured using a 3.4-kt yr exposure of the IMB-3 detector. Single-ring events are classified as showering or nonshowering using the geometry of the {hacek C}erenkov pattern. A simulation of neutrino interactions and three models of atmospheric neutrino production are used to predict the composition of the sample. Showering-nonshowering character is strongly correlated with the flavor of the neutrino parent. In the lepton momentum range {ital p}{lt}1500 MeV/{ital c}, we find that nonshowering events comprise (41{plus minus}3{plus minus}2syst)% of the total. The fraction expected is (51{plus minus}5(syst))%.

  3. Radiation Belt Electron Dynamics: Modeling Atmospheric Losses

    NASA Technical Reports Server (NTRS)

    Selesnick, R. S.

    2003-01-01

    The first year of work on this project has been completed. This report provides a summary of the progress made and the plan for the coming year. Also included with this report is a preprint of an article that was accepted for publication in Journal of Geophysical Research and describes in detail most of the results from the first year of effort. The goal for the first year was to develop a radiation belt electron model for fitting to data from the SAMPEX and Polar satellites that would provide an empirical description of the electron losses into the upper atmosphere. This was largely accomplished according to the original plan (with one exception being that, for reasons described below, the inclusion of the loss cone electrons in the model was deferred). The main concerns at the start were to accurately represent the balance between pitch angle diffusion and eastward drift that determines the dominant features of the low altitude data, and then to accurately convert the model into simulated data based on the characteristics of the particular electron detectors. Considerable effort was devoted to achieving these ends. Once the model was providing accurate results it was applied to data sets selected from appropriate periods in 1997, 1998, and 1999. For each interval of -30 to 60 days, the model parameters were calculated daily, thus providing good short and long term temporal resolution, and for a range of radial locations from L = 2.7 to 3.9. .

  4. Surface ices and the atmospheric composition of Pluto

    NASA Technical Reports Server (NTRS)

    Owen, Tobias C.; Roush, Ted L.; Cruikshank, Dale P.; Elliot, James L.; Young, Leslie A.; De Bergh, Catherine; Schmitt, Bernard; Geballe, Thomas R.; Brown, Robert H.; Bartholomew, Mary J.

    1993-01-01

    Observations of the 1.4- to 2.4-micrometer spectrum of Pluto reveal absorptions of carbon monoxide and nitrogen ices and confirm the presence of solid methane. Frozen nitrogen is more abundant than the other two ices by a factor of about 50; gaseous nitrogen must therefore be the major atmospheric constituent. The absence of carbon dioxide absorptions is one of several differences between the spectra of Pluto and Triton in this region. Both worlds carry information about the composition of the solar nebula and the processes by which icy planetesimals formed.

  5. Jupiter's atmospheric composition from the Cassini thermal infrared spectroscopy experiment

    NASA Technical Reports Server (NTRS)

    Kunde, V. G.; Flasar, F. M.; Jennings, D. E.; Bezard, B.; Strobel, D. F.; Conrath, B. J.; Nixon, C. A.; Bjoraker, G. L.; Romani, P. N.; Achterberg, R. K.; Simon-Miller, A. A.; Irwin, P.; Brasunas, J. C.; Pearl, J. C.; Smith, M. D.; Orton, G. S.; Gierasch, P. J.; Spilker, L. J.; Carlson, R. C.; Mamoutkine, A. A.; Calcutt, S. B.; Read, P. L.; Taylor, F. W.; Fouchet, T.; Parrish, P.

    2004-01-01

    The Composite Infrared Spectrometer observed Jupiter in the thermal infrared during the swing-by of the Cassini spacecraft. Results include the detection of two new stratospheric species, the methyl radical and diacetylene, gaseous species present in the north and south auroral infrared hot spots; determination of the variations with latitude of acetylene and ethane, the latter a tracer of atmospheric motion; observations of unexpected spatial distributions of carbon dioxide and hydrogen cyanide, both considered to be products of comet Shoemaker-Levy 9 impacts; characterization of the morphology of the auroral infrared hot spot acetylene emission; and a new evaluation of the energetics of the northern auroral infrared hot spot.

  6. Towards an exploitation of IAGOS atmospheric composition measurements

    NASA Astrophysics Data System (ADS)

    Marshall, Julia; Gerbig, Christoph; Petzold, Andreas; Zahn, Andreas

    2015-04-01

    IAGOS, In-service Aircraft for a Global Observing System, has installed instrumentation on a growing fleet of commercial airliners in order to continuously monitor atmospheric composition around the globe. IAGOS is providing accurate in situ observations of greenhouse gases (GHGs), reactive gases, aerosols, and cloud particles at high spatial resolution in the free atmosphere, thereby covering the essential climate variables (ECVs) for atmospheric composition as designated by the GCOS programme (Implementation Plan for the Global Observing System for Climate in Support of the UNFCCC, 2010). The greenhouse gas measurements made by IAGOS will be submitted to the WMO/GAW World Data Centre for Greenhouse Gases (WDCGG). Within the EU FP7 project IGAS (IAGOS for the GMES Atmospheric Service), the links between this new data stream and scientific users, including the Copernicus Atmosphere Monitoring Service, are being improved. This includes the provision of measurements in both near-real-time and delayed mode, and improved accessibility to the data through linkages to the databases of both the German Aerospace Centre (DLR) flight campaign archive and the Copernicus data archive. Work has been undertaken to investigate the use of the near-real-time profile measurements in order to correct bias in satellite measurements assimilated by the Copernicus Atmosphere Monitoring Service. Documentation of the QA/QC procedures and measurement techniques for each instrument have been formalized and reviewed by external experts, to provide users with a measurement traceable to WMO standards. The representativeness of the measurements has been assessed, to better interpret results in polluted regions and near the tropopause. The potential impact of the GHG measurements on regional scale flux inversions has been quantified, which is relevant for ICOS (Integrated Carbon Observing System). Finally, tools have been developed to use the measurements for validation of satellite column

  7. Validation of Atmospheric Dynamics (VADY) - connections between planetary waves and atmospheric circulation types

    NASA Astrophysics Data System (ADS)

    Lang, Benjamin; Jacobeit, Jucundus; Beck, Christoph; Philipp, Andreas

    2015-04-01

    The climate research program "Medium-range Climate Predictions" (MiKlip), funded by the Federal Ministry of Education and Research in Germany (BMBF), has the aim to develop a climate model system (MPI-ESM) that can provide reliable decadal predictions of climate, including extreme weather events. A substantial part of the development process is a comprehensive model validation. Within MiKlip, it includes comparisons of model simulations and observations in order to allow statements about the performance of the model and to give particular recommendations for the further development of the model. The research project "Validation of Atmospheric Dynamics" (VADY), conducted by the cooperation partners "Institute of Geography at the University of Augsburg" (IGUA) and the "German Aerospace Centre" (DLR), contributes to model validation within MiKlip with a special focus on atmospheric waves and circulation dynamics. Within the framework of VADY, DLR validates the representation of atmospheric waves on different levels and scales based on suitable activity indices (e.g. the so-called large-scale dynamical activity index (LDAI), which is a measure for the activity of planetary waves). The focus of IGUA is on the model validation with respect to the representation of atmospheric circulation types, dynamical modes and the teleconnectivity of the atmospheric circulation. Currently, the connection between LDAI and atmospheric circulation types on different levels and for different seasons in the North Atlantic-European region is analysed by considering, in particular, the North Atlantic Oscillation. Results will be shown for the connection between LDAI and atmospheric circulation types and subsequently for the representation of the identified connections in the decadal-prediction model system of MPI-ESM.

  8. Atmospheric Dynamics of the Outer Planets

    NASA Technical Reports Server (NTRS)

    Ingersoll, Andrew P.

    2002-01-01

    The giant planets-Jupiter, Saturn, Uranus, and Neptune-are fluid objects. The winds are powered by absorbed sunlight, as on earth, and by internal heat left over from planetary formation. The main constituents of the atmospheres are hydrogen and helium. The clouds are made of ammonia, hydrogen sulphide, and water. All four giant planets are banded, with multiple zonal jet streams. Even Uranus, whose spin axis is tipped by 98deg relative to the orbit axis, shows latitudinal banding and zonal jets. Equator-to-pole temperature differences are close to zero. Wind speeds are larger than on earth and do not decrease with distance from the sun. Although the power/area at Neptune is only 1/20 that at Jupiter, the winds at Neptune are three times stronger. Stable vortices like the Great Red Spot of Jupiter and similar spots on Neptune come in all size ranges and exhibit a variety of behaviours including merging, orbiting, filament ejection, and oscillating in both shape and position. At least at cloud-top levels, 90% of the long-lived vortices are anticyclonic and sit in anticyclonic shear zones. Features in the cyclonic zones tend to be chaotic, with lifetimes of several days or less. These mesoscale eddies tend to have lightning in them, which suggests that they get their energy from moist convection. The rate of conversion of eddy kinetic energy into kinetic energy of the zonal jets is more than 10% of the power/area radiated by Jupiter. This fraction is more than an order of magnitude larger than on earth. Several lines of evidence now indicate that the winds at cloud-top levels are the surface manifestation of deep-rooted motions that extend into the interior and are presumably driven by internal heat.

  9. Saturn's Atmospheric Composition from Observations by the Cassini/Composite Infrared Spectrometer

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Young, M.; LeClair, A. C.; Achterberg, R. K.; Flasar, F. M.; Kunde, V. G.

    2010-01-01

    Thermal emission infrared observation of Saturn s atmosphere are being made by the Composite Infrared Spectrometer (CIRS) aboard the Cassini spacecraft since its insertion in Saturn s orbit on July 2nd, 2004. The measurements made in both limb and nadir modes of observations consist of infrared spectra in the 10-1400/cm region with a variable spectral resolution of 0.53/cm and 2.8/cm, and exhibit rotational and vibrational spectral features that may be analyzed for retrieval of the thermal structure and constituent distribution of Saturn s atmosphere. In this paper, we present a comprehensive analysis of the CIRS infrared observed spectra for retrieval of Saturn s atmospheric composition focusing on the distributions of some selected hydrocarbons, phosphine, ammonia, and possible determination of the isotopic ratios of some species with sufficiently strong isolated spectral features. A comparison of the retrieved constituent distributions with the available data in the literature will be made.

  10. Deterministic Chaos in Tropical Atmospheric Dynamics.

    NASA Astrophysics Data System (ADS)

    Waelbroeck, H.

    1995-07-01

    An 11-year dataset from the tropical weather station of Tlaxcala, Mexico, is examined. It is found that mutual information drops quickly with the delay, to a positive value that relaxes to zero with a timescale of 20 days. The mutual dependence of the observables is also examined and it is concluded that the dataset gives the equivalent of eight variables per day, known to a precision of 2%. It is determined that the effective dimension of the attractor is Deff 11.7 at the scale 3.5% < R/Rmax < 8%. Evidence is found that the effective dimension increases as R/Rmax 0, supporting a conjecture by Lorenz that the climate system may consist of a large number of weakly coupled subsystems, some of which have low-dimensional attractors. A local reconstruction of the dynamics in phase space is performed; the short-term predictability is modest and agrees with theoretical estimates. Useful skill in predictions of 10-day rainfall accumulation anomalies reflects the persistence of weather patterns, which follow the 20-day decay rate of the mutual information.

  11. Investigations of atmospheric dynamics using a CW Doppler sounder array

    NASA Technical Reports Server (NTRS)

    Rao, G. L.

    1974-01-01

    A three-dimensional CW Doppler sounding system currently under operation at the NASA-Marshall Space Flight Center, Alabama is described. The properties of the neutral atmosphere are discussed along with the theory of Doppler sounding technique. Methods of data analyses used to investigate the dynamical phenomena at the ionospheric heights are presented and suggestions for future investigations provided.

  12. The Wmo Global Atmosphere Watch Programme: Global Framework for Atmospheric Composition Observations and Analysis

    NASA Astrophysics Data System (ADS)

    Tarasova, O. A.; Jalkanen, L.

    2010-12-01

    The WMO Global Atmosphere Watch (GAW) Programme is the only existing long-term international global programme providing an international coordinated framework for observations and analysis of the chemical composition of the atmosphere. GAW is a partnership involving contributors from about 80 countries. It includes a coordinated global network of observing stations along with supporting facilities (Central Facilities) and expert groups (Scientific Advisory Groups, SAGs and Expert Teams, ETs). Currently GAW coordinates activities and data from 27 Global Stations and a substantial number of Regional and Contributing Stations. Station information is available through the GAW Station Information System GAWSIS (http://gaw.empa.ch/gawsis/). There are six key groups of variables which are addressed by the GAW Programme, namely: ozone, reactive gases, greenhouse gases, aerosols, UV radiation and precipitation chemistry. GAW works to implement integrated observations unifying measurements from different platforms (ground based in situ and remote, balloons, aircraft and satellite) supported by modeling activities. GAW provides data for ozone assessments, Greenhouse Gas Bulletins, Ozone Bulletins and precipitation chemistry assessments published on a regular basis and for early warnings of changes in the chemical composition and related physical characteristics of the atmosphere. To ensure that observations can be used for global assessments, the GAW Programme has developed a Quality Assurance system. Five types of Central Facilities dedicated to the six groups of measurement variables are operated by WMO Members and form the basis of quality assurance and data archiving for the GAW global monitoring network. They include Central Calibration Laboratories (CCLs) that host primary standards (PS), Quality Assurance/Science Activity Centres (QA/SACs), World Calibration Centers (WCCs), Regional Calibration Centers (RCCs), and World Data Centers (WDCs) with responsibility for

  13. Argon isotopic composition of Archaean atmosphere probes early Earth geodynamics.

    PubMed

    Pujol, Magali; Marty, Bernard; Burgess, Ray; Turner, Grenville; Philippot, Pascal

    2013-06-06

    Understanding the growth rate of the continental crust through time is a fundamental issue in Earth sciences. The isotopic signatures of noble gases in the silicate Earth (mantle, crust) and in the atmosphere afford exceptional insight into the evolution through time of these geochemical reservoirs. However, no data for the compositions of these reservoirs exists for the distant past, and temporal exchange rates between Earth's interior and its surface are severely under-constrained owing to a lack of samples preserving the original signature of the atmosphere at the time of their formation. Here, we report the analysis of argon in Archaean (3.5-billion-year-old) hydrothermal quartz. Noble gases are hosted in primary fluid inclusions containing a mixture of Archaean freshwater and hydrothermal fluid. Our analysis reveals Archaean atmospheric argon with a (40)Ar/(36)Ar value of 143 ± 24, lower than the present-day value of 298.6 (for which (40)Ar has been produced by the radioactive decay of the potassium isotope (40)K, with a half-life of 1.25 billion years; (36)Ar is primordial in origin). This ratio is consistent with an early development of the felsic crust, which might have had an important role in climate variability during the first half of Earth's history.

  14. Influence of Atmospheric Pressure and Composition on LIBS

    SciTech Connect

    Hatch, Jeremy J.; Scott, Jill R.; Effenberger, A. J. Jr.

    2014-03-01

    Most LIBS experiments are conducted at standard atmospheric pressure in air. However, there are LIBS studies that vary the pressure and composition of the gas. These studies have provided insights into fundamentals of the mechanisms that lead to the emission and methods for improving the quality of LIBS spectra. These atmospheric studies are difficult because the effects of pressure and gas composition and interconnected, making interpretation of the results difficult. The influence of pressures below and above 760 Torr have been explored. Performing LIBS on a surface at reduced pressures (<760 Torr) can result in enhanced spectra due to higher resolution, increased intensity, improved signal-to-noise (S/N), and increased ablation. Lower pressures produce increased resolution because the line width in LIBS spectra is predominantly due to Stark and Doppler broadening. Stark broadening is primarily caused from collisions between electrons and atoms, while Doppler broadening is proportional to the plasma temperature. Close examination using a high resolution spectrometer reveals that spectra show significant peak broadening and self-absorption as pressures increase, especially for pressures >760 Torr. During LIBS plasma expansion, energy is lost to the surrounding atmosphere, which reduces the lifetime of the laser plasma. Therefore, reducing the pressure increases the lifetime of the plasma, allowing more light from the laser plasma to be collected; thus, increasing the observed signal intensity. However, if pressures are too low (<10 Torr), then there is a steep drop in LIBS spectral intensity. This loss in intensity is mostly due to a disordered plasma that results from the lack of sufficient atmosphere to provide adequate confinement. At reduced pressures, the plasma expands into a less dense atmosphere, which results in a less dense shock wave. The reduced density in the shock wave results in reduced plasma shielding, allowing more photons to reach the sample

  15. Dynamic Data-Driven Event Reconstruction for Atmospheric Releases

    SciTech Connect

    Mirin, A A; Kosovic, B

    2007-03-29

    Accidental or terrorist releases of hazardous materials into the atmosphere can impact large populations and cause significant loss of life or property damage. Plume predictions have been shown to be extremely valuable in guiding an effective and timely response. The two greatest sources of uncertainty in the prediction of the consequences of hazardous atmospheric releases result from poorly characterized source terms and lack of knowledge about the state of the atmosphere as reflected in the available meteorological data. We have developed a new event reconstruction methodology that provides probabilistic source term estimates from field measurement data for both accidental and clandestine releases. Accurate plume dispersion prediction requires the following questions to be answered: What was released? When was it released? How much material was released? Where was it released? We have developed a dynamic-data-driven event reconstruction capability that couples data and predictive methods through Bayesian inference to obtain a solution to this inverse problem. The solution consists of a probability distribution of unknown source term parameters. For consequence assessment, we then use this probability distribution to construct a 'composite' forward plume prediction that accounts for the uncertainties in the source term. Since in most cases of practical significance it is impossible to find a closed form solution, Bayesian inference is accomplished by utilizing stochastic sampling methods. This approach takes into consideration both measurement and forward model errors and thus incorporates all the sources of uncertainty in the solution to the inverse problem. Stochastic sampling methods have the additional advantage of being suitable for problems characterized by a non-Gaussian distribution of source term parameters and for cases in which the underlying dynamical system is nonlinear. We initially developed a Markov Chain Monte Carlo (MCMC) stochastic methodology

  16. Measured Spacecraft Dynamic Effects on Atmospheric Science Instruments

    NASA Technical Reports Server (NTRS)

    Woodard, Stanley E.; Gell, David A.; Lay, Richard R.

    1997-01-01

    On September 1991, NASA launched the Upper Atmosphere Research Satellite. In addition to its atmospheric science mission, spacecraft dynamic effects on science measurements were analyzed. The investigation included two in-flight experiments to determine how each on-board instrument, subsystem and environmental disturbance contributed to the spacecraft dynamic response and how these disturbances affected science measurements. Three case studies are presented which show the impact of spacecraft dynamic response on science measurements. In the first case, correlation of independent atmospheric meridional wind measurements taken by two instruments with the spacecraft dynamic response demonstrated that excessive vibration (exceeding instrument pointing requirements) resulted in wind measurement disagreement. In the second case, solar array disturbances produced a spacecraft response signature on radiometer measurements. The signature explicitly demonstrated that if an instrument has sufficient spatial and temporal resolution, spacecraft dynamic response could impact measurements. In the final case, correlation of an instrument's fine sun sensor data and CO2 measurements demonstrated the effect of temporal and spatial sampling resolution and active pointing control on science measurements. The sun sensor had a frequency modulated characteristic due to spacecraft vibration and the periodic scanning of another instrument which was not present on the CO2 measurements.

  17. Pivotal roles of phyllosphere microorganisms at the interface between plant functioning and atmospheric trace gas dynamics

    PubMed Central

    Bringel, Françoise; Couée, Ivan

    2015-01-01

    The phyllosphere, which lato sensu consists of the aerial parts of plants, and therefore primarily, of the set of photosynthetic leaves, is one of the most prevalent microbial habitats on earth. Phyllosphere microbiota are related to original and specific processes at the interface between plants, microorganisms and the atmosphere. Recent –omics studies have opened fascinating opportunities for characterizing the spatio-temporal structure of phyllosphere microbial communities in relation with structural, functional, and ecological properties of host plants, and with physico-chemical properties of the environment, such as climate dynamics and trace gas composition of the surrounding atmosphere. This review will analyze recent advances, especially those resulting from environmental genomics, and how this novel knowledge has revealed the extent of the ecosystemic impact of the phyllosphere at the interface between plants and atmosphere. Highlights • The phyllosphere is one of the most prevalent microbial habitats on earth. • Phyllosphere microbiota colonize extreme, stressful, and changing environments. • Plants, phyllosphere microbiota and the atmosphere present a dynamic continuum. • Phyllosphere microbiota interact with the dynamics of volatile organic compounds and atmospheric trace gasses. PMID:26052316

  18. Reaction Profiles and Molecular Dynamics Simulations of Cyanide Radical Reactions Relevant to Titan's Atmosphere

    NASA Astrophysics Data System (ADS)

    Trinidad Pérez-Rivera, Danilo; Romani, Paul N.; Lopez-Encarnacion, Juan Manuel

    2016-10-01

    Titan's atmosphere is arguably the atmosphere of greatest interest that we have an abundance of data for from both ground based and spacecraft observations. As we have learned more about Titan's atmospheric composition, the presence of pre-biotic molecules in its atmosphere has generated more and more fascination about the photochemical process and pathways it its atmosphere. Our computational laboratory has been extensively working throughout the past year characterizing nitrile synthesis reactions, making significant progress on the energetics and dynamics of the reactions of .CN with the hydrocarbons acetylene (C2H2), propylene (CH3CCH), and benzene (C6H6), developing a clear picture of the mechanistic aspects through which these three reactions proceed. Specifically, first principles calculations of the reaction profiles and molecular dynamics studies for gas-phase reactions of .CN and C2H2, .CN and CH3CCH, and .CN and C6H6 have been carried out. A very accurate determination of potential energy surfaces of these reactions will allow us to compute the reaction rates which are indispensable for photochemical modeling of Titan's atmosphere.The work at University of Puerto Rico at Cayey was supported by Puerto Rico NASA EPSCoR IDEAS-ER program (2015-2016) and DTPR was sponsored by the Puerto Rico NASA Space Grant Consortium Fellowship. *E-mail: juan.lopez15@upr.edu

  19. An exploration of Saturn's atmospheric dynamics with Global Climate Modeling

    NASA Astrophysics Data System (ADS)

    Spiga, Aymeric; Guerlet, Sandrine; Indurain, Mikel; Meurdesoif, Yann; Millour, Ehouarn; Sylvestre, Mélody; Dubos, Thomas; Fouchet, Thierry

    2015-04-01

    A decade of Cassini observations has yielded a new vision on the dynamical phenomena in Saturn's troposphere and stratosphere. Several puzzling signatures (equatorial oscillations with a period of about half a Saturn year, interhemispheric circulations affecting the hydrocarbons' distribution, including possible effects of rings shadowing, sudden warming associated with the powerful 2010 Great White Spot) cannot be explained by current photochemical and radiative models, which do not include dynamics. We therefore suspect that 1. the observed anomalies arise from large-scale dynamical circulations and 2. those large-scale dynamical motions are driven by atmospheric waves, eddies, and convection, in other words fundamental mechanisms giving birth to, e.g., the Quasi-Biennal Oscillation and Brewer-Dobson circulation in the Earth's middle atmosphere. We explore the plausibility of this scenario using our new Global Climate Modeling (GCM) for Saturn. To build this model, we firstly formulated dedicated physical parameterizations for Saturn's atmosphere, with a particular emphasis on radiative computations (using a correlated-k radiative transfer model, with radiative species and spectral discretization tailored for Saturn) aimed at both efficiency and accuracy, and validated them against existing Cassini observations. A second step consisted in coupling this radiative model to an hydrodynamical solver to predict the three-dimensional evolution of Saturn's tropospheric and stratospheric flow. We will provide an analysis of the first results of those dynamical simulations, with a focus on the development of baroclinic and barotropic instability, on eddy vs. mean flow interactions, and how this could relate to the enigmatic signatures observed by Cassini. Preliminary high-resolution simulations with a new icosahedral dynamical solver adapted to high-performance computing will also be analyzed. Perspectives are twofold: firstly, broadening our fundamental knowledge of

  20. Role of megafauna and frozen soil in the atmospheric CH4 dynamics.

    PubMed

    Zimov, Sergey; Zimov, Nikita

    2014-01-01

    Modern wetlands are the world's strongest methane source. But what was the role of this source in the past? An analysis of global 14C data for basal peat combined with modelling of wetland succession allowed us to reconstruct the dynamics of global wetland methane emission through time. These data show that the rise of atmospheric methane concentrations during the Pleistocene-Holocene transition was not connected with wetland expansion, but rather started substantially later, only 9 thousand years ago. Additionally, wetland expansion took place against the background of a decline in atmospheric methane concentration. The isotopic composition of methane varies according to source. Owing to ice sheet drilling programs past dynamics of atmospheric methane isotopic composition is now known. For example over the course of Pleistocene-Holocene transition atmospheric methane became depleted in the deuterium isotope, which indicated that the rise in methane concentrations was not connected with activation of the deuterium-rich gas clathrates. Modelling of the budget of the atmospheric methane and its isotopic composition allowed us to reconstruct the dynamics of all main methane sources. For the late Pleistocene, the largest methane source was megaherbivores, whose total biomass is estimated to have exceeded that of present-day humans and domestic animals. This corresponds with our independent estimates of herbivore density on the pastures of the late Pleistocene based on herbivore skeleton density in the permafrost. During deglaciation, the largest methane emissions originated from degrading frozen soils of the mammoth steppe biome. Methane from this source is unique, as it is depleted of all isotopes. We estimated that over the entire course of deglaciation (15,000 to 6,000 year before present), soils of the mammoth steppe released 300-550 Pg (10(15) g) of methane. From current study we conclude that the Late Quaternary Extinction significantly affected the global

  1. Dynamic Probabilistic Instability of Composite Structures

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.

    2009-01-01

    A computationally effective method is described to evaluate the non-deterministic dynamic instability (probabilistic dynamic buckling) of thin composite shells. The method is a judicious combination of available computer codes for finite element, composite mechanics and probabilistic structural analysis. The solution method is incrementally updated Lagrangian. It is illustrated by applying it to thin composite cylindrical shell subjected to dynamic loads. Both deterministic and probabilistic buckling loads are evaluated to demonstrate the effectiveness of the method. A universal plot is obtained for the specific shell that can be used to approximate buckling loads for different load rates and different probability levels. Results from this plot show that the faster the rate, the higher the buckling load and the shorter the time. The lower the probability, the lower is the buckling load for a specific time. Probabilistic sensitivity results show that the ply thickness, the fiber volume ratio and the fiber longitudinal modulus, dynamic load and loading rate are the dominant uncertainties in that order.

  2. Nonlinear dynamics of global atmospheric and earth system processes

    NASA Technical Reports Server (NTRS)

    Zhang, Taiping; Verbitsky, Mikhail; Saltzman, Barry; Mann, Michael E.; Park, Jeffrey; Lall, Upmanu

    1995-01-01

    During the grant period, the authors continued ongoing studies aimed at enhancing their understanding of the operation of the atmosphere as a complex nonlinear system interacting with the hydrosphere, biosphere, and cryosphere in response to external radiative forcing. Five papers were completed with support from the grant, representing contributions in three main areas of study: (1) theoretical studies of the interactive atmospheric response to changed biospheric boundary conditions measurable from satellites; (2) statistical-observational studies of global-scale temperature variability on interannual to century time scales; and (3) dynamics of long-term earth system changes associated with ice sheet surges.

  3. Infrasound monitoring, acoustic-gravity waves and global atmospheric dynamics

    NASA Astrophysics Data System (ADS)

    Blanc, E.; Le Pichon, A.; Ceranna, L.; Farges, T.

    2008-12-01

    For the verification of the Comprehensive nuclear Test Ban Treaty, the International Monitoring System has been developed. As part of this system, the infrasound network provides an unique opportunity to monitor continuously pressure waves in the atmosphere. Such infrasonic waves propagate in the channel formed by the temperature and wind gradients of the atmosphere. Long term observations provide information about the evolution of the propagation conditions and then of atmospheric parameters. The monitoring of continuous sources, as ocean swell, gives the characteristics of the stratospheric wave channel submitted to stratospheric warming effects. Large scale gravity waves, which are also observed by the network, produce a forcing of the stratosphere at low and middle latitudes and long-lived changes in the stratospheric circulation towards high latitudes, leading to fluctuations in the strength of the polar vortex. These fluctuations move down to the lower stratosphere with possible effects on the tropospheric temperature. Gravity wave monitoring in Antarctica reveals a gravity wave system probably related to the wind effect over mountains. At mid latitudes an additional main sources of disturbances is the thunderstorm activity. The infrasound monitoring system allows a better knowledge of the atmospheric wave systems and of the dynamics of the atmosphere. In return this better knowledge of the wave systems allow a better identification of the possible explosion signals in the background of the atmospheric waves and then to improve the discrimination methods

  4. Lidar determination of the composition of atmosphere aerosols

    NASA Technical Reports Server (NTRS)

    Wright, M. L.

    1980-01-01

    Theoretical and experimental studies of the feasibility of using DIfferential SCatter (DISC) lidar to measure the composition of atmospheric aerosols are described. This technique involves multiwavelength measurements of the backscatter cross section of aerosols in the middle infrared, where a number of materials display strong restrahlen features that significantly modulate the backscatter spectrum. The theoretical work indicates that a number of materials of interest, including sulfuric acid, ammonium sulfate, and silicates, can be discriminated among with a CO2 lidar. An initial evaluation of this procedure was performed in which cirrus clouds and lower altitude tropospheric aerosols were developed. The observed ratio spectrum of the two types of aerosol displays structure that is in crude accord with theoretical expectations.

  5. Factors influencing atmospheric composition over subarctic North America during summer

    NASA Technical Reports Server (NTRS)

    Wofsy, Steven C.; Fan, S. -M.; Blake, D. R.; Bradshaw, J. D.; Sandholm, S. T.; Singh, H. B.; Sachse, G. W.; Harriss, R. C.

    1994-01-01

    Elevated concentrations of hydrocarbons, CO, and nitrogen oxides were observed in extensive haze layers over northeastern Canada in the summer of 1990, during ABLE 3B. Halocarbon concentrations remained near background in most layers, indicating a source from biomass wildfires. Elevated concentrations of C2Cl4 provided a sensitive indicator for pollution from urban/industrial sources. Detailed analysis of regional budgets for CO and hydrocarbons indicates that biomass fires accounted for approximately equal to 70% of the input to the subarctic for most hydrocarbons and for acetone and more than 50% for CO. Regional sources for many species (including CO) exceeded chemical sinks during summer, and the boreal region provided a net source to midlatitudes. Interannual variations and long-term trends in atmospheric composition are sensitive to climatic change; a shift to warmer, drier conditions could increase the areas burned and thus the sources of many trace gases.

  6. Effects of cirrus composition on atmospheric radiation budgets

    NASA Technical Reports Server (NTRS)

    Kinne, Stefan; Liou, Kuo-Nan

    1988-01-01

    A radiative transfer model that can be used to determine the change in solar and infrared fluxes caused by variations in the composition of cirrus clouds was used to investigate the importance of particle size and shape on the radiation budget of the Earth-atmosphere system. Even though the cloud optical thickness dominates the radiative properties of ice clouds, the particle size and nonsphericity of ice crystals are also important in calculations of the transfer of near-IR solar wavelengths. Results show that, for a given optical thickness, ice clouds composed of larger particles would produce larger greenhouse effects than those composed of smaller particles. Moreover, spherical particles with equivalent surface areas, frequently used for ice crystal clouds, would lead to an overestimation of the greenhouse effect.

  7. Changes in atmospheric composition inferred from ionospheric production rates

    NASA Technical Reports Server (NTRS)

    Titheridge, J. E.

    1974-01-01

    Changes in the total electron content of the ionosphere near sunrise are used to determine the integrated production rate in the ionosphere (Q) from 1965 to 1971 at latitudes of 34S, 20N, and 34N. The observed regular semiannual variation in Q through a range of 1:3:1 is interpreted as an increase in the ratio O/N2 (relative densities) near the equinoxes. It follows that there is a worldwide semiannual variation in atmospheric composition, with the above ratio maximum just after the equinoxes. There is a large seasonal variation in the Northern hemisphere with a maximum in mid-summer. This effect is absent in the Southern hemisphere. At all times except solar maximum in the Northern hemisphere there is a global asymmetry. The ratio O/N2 is about three times as large in the Northern hemisphere. The overall mechanism appears to be N2 absorption.

  8. Composition and oxidation state of sulfur in atmospheric particulate matter

    NASA Astrophysics Data System (ADS)

    Longo, Amelia F.; Vine, David J.; King, Laura E.; Oakes, Michelle; Weber, Rodney J.; Huey, Lewis Gregory; Russell, Armistead G.; Ingall, Ellery D.

    2016-10-01

    The chemical and physical speciation of atmospheric sulfur was investigated in ambient aerosol samples using a combination of sulfur near-edge x-ray fluorescence spectroscopy (S-NEXFS) and X-ray fluorescence (XRF) microscopy. These techniques were used to determine the composition and oxidation state of sulfur in common primary emission sources and ambient particulate matter collected from the greater Atlanta area. Ambient particulate matter samples contained two oxidation states: S0 and S+VI. Ninety-five percent of the individual aerosol particles (> 1 µm) analyzed contain S0. Linear combination fitting revealed that S+VI in ambient aerosol was dominated by ammonium sulfate as well as metal sulfates. The finding of metal sulfates provides further evidence for acidic reactions that solubilize metals, such as iron, during atmospheric transport. Emission sources, including biomass burning, coal fly ash, gasoline, diesel, volcanic ash, and aerosolized Atlanta soil, and the commercially available bacterium Bacillus subtilis, contained only S+VI. A commercially available Azotobacter vinelandii sample contained approximately equal proportions of S0 and S+VI. S0 in individual aerosol particles most likely originates from primary emission sources, such as aerosolized bacteria or incomplete combustion.

  9. Effect of flares on the chemical composition of exoplanets atmospheres

    NASA Astrophysics Data System (ADS)

    Venot, O.; Decin, L.

    2015-10-01

    M stars are very abundant in our Galaxy, and very likely harbour the majority of planetary systems. But a particularity of M stars is that they are the most active class of stars. Indeed, they experience stellar variability such as flares. These violent and unpredictable outbursts originate from the photosphere and are caused by magnetic processus. During such an event, the energy emitted by the star can vary by several orders of magnitude for the whole wavelength range. It results in an enhancement of the H# emission and of the continuum. Different studies on the effect of flares on exoplanets have already been conducted [1, 2]. Here we are interested in the effect of a flare on the atmospheric composition of a warm Neptune orbiting around an M star. Using the stellar flux of AD Leo recorded during a flare event [1] and the chemical model of [3], we have studied the impact on the atmosphere. We have also computed the synthetic spectra assuming that such an event occurs during a transit. We will present these results.

  10. The Sentinel-4 Mission and its Atmospheric Composition Producs

    NASA Astrophysics Data System (ADS)

    Veihelmann, Ben; Meijer, Yasjka; Ingmann, Paul; Koopman, Rob; Wright, Norrie; Courreges-Lacoste, Gregory Bazalgette; Bagnasco, Glorgio

    2016-08-01

    The Sentinel-4 (S4) mission is an element of the Copernicus Space Component dedicated to atmospheric composition. The mission is implemented as an Ultra- violet Visible Near infrared spectrometer (S4/UVN) embarked on the geostationary Meteosat Third Generation-Sounder (MTG-S) platforms (see Fig. 1). The S4/UVN instrument measures Earth radiance and solar irradiance over Europe with a revisit time of one hour and a spatial sampling distance of 8 km (at the reference location at 45°N). The mission will provide hourly measurements of tropospheric amounts of NO2 (Nitrogen dioxide), O3 (Ozone), SO2 (Sulfur dioxide), HCHO (Formaldehyde), CHOCHO (glyoxal), and aerosols in support of the air quality applications of the Copernicus Atmosphere Monitoring Services. Two S4/UVN instruments will be embarked on the geostationary MTG-S platforms. The Flight Acceptance Review of the first MTG-S satellite is expected to take place in the first quarter of 2021. The expected S4 mission lifetime spans 15 years.

  11. Structural dynamic analysis of composite beams

    NASA Astrophysics Data System (ADS)

    Suresh, J. K.; Venkatesan, C.; Ramamurti, V.

    1990-12-01

    In the treatment of the structural dynamic problem of composite materials, two alternate types of formulations, based on the elastic modulus and compliance quantities, exist in the literature. The definitions of the various rigidities are observed to differ in these two approaches. Following these two types of formulation, the structural dynamic characteristics of a composite beam are analyzed. The results of the analysis are compared with those available in the literature. Based on the comparison, the influence of the warping function in defining the coupling terms in the modulus approach and also on the natural frequencies of the beam has been identified. It is found from the analysis that, in certain cases, the difference between the results of the two approaches is appreciable. These differences may be attributed to the constraints imposed on the deformation and flexibility of the beam by the choice of the description of the warping behaviour. Finally, the influence of material properties on the structural dynamic characteristics of the beam is studied for different composites for various angles of orthotropy.

  12. A generalized tensor formulation of atmosphere and seas dynamics

    NASA Technical Reports Server (NTRS)

    Avis, L. M.; Turner, R. E.; Rees, T. H.

    1975-01-01

    A generalized mathematical model was developed for simulation of the dynamics and transport of both the atmosphere and seas. A nearly horizontal bottom coordinate surface conforms to the land-to-air interface and the sea-floor-to-water interface, which simplifies computations. General vertical motion of the other quasi-horizontal coordinate surfaces is allowed; external gravity waves can be represented by the top coordinate surface, and meteorological fronts and inversion layers in the atmosphere and refractive layers in the seas can be represented with enhanced resolution by the internal quasi-horizontal coordinate surfaces. A tensor reformulation of the standard subgrid mixing theory departs significantly from the standard theory in allowing, as a solution under adiabatic conditions, rigid-body rotation of the atmosphere.

  13. Global dynamics and thermal structure of Jupiter's atmosphere

    NASA Technical Reports Server (NTRS)

    Flasar, F. M.

    1986-01-01

    Voyager flyby observations have yielded the first detailed maps of wind and temperature fields in the Jupiter atmosphere; these data indicate that Jupiter's zonal currents violate the barotropic instability criterion if they extend only a few scale heights below the cloud tops. Microwave observations at mm and cm wavelengths have probed the atmosphere down to a level of about 7 bars, thereby constraining horizontal and vertical thermal structure in a region of the atmosphere about which little was known. Temporal variations in the temperature field suggest that dynamical processes may be important in the establishment of tropopause structure on short time scales. Ground-based and Voyager observations have also indicated a hemispheric asymmetry in temperature in the upper stratosphere.

  14. The dynamics in the upper atmospheres of Mars and Titan

    NASA Astrophysics Data System (ADS)

    Bell, Jared M.

    2008-06-01

    This thesis explores the dynamics of two terrestrial bodies: Mars and Titan. At Mars, the coupled Mars General Circulation Model - Mars Thermospheric General Circulation Model (MGCM-MTGCM) is employed to investigate the phenomenon known as Mars winter polar warming. At Titan, a new theoretical model, the Titan Global Ionosphere - Thermosphere Model (T-GITM), is developed, based upon previous work by Ridley et al. [2006]. Using this new model, three separate numerical studies quantify the impacts of solar cycle, seasons, and lower boundary zonal winds on the Titan thermosphere structure and dynamics. At Mars, this thesis investigates thermospheric winter polar warming through three major studies: (1) a systematic analysis of vertical dust mixing in the lower atmosphere and its impact upon the dynamics of the lower thermosphere (100-130 km), (2) an interannual investigation utilizing three years of lower atmosphere infrared (IR) dust optical depth data acquired by the Thermal Emission Spectrometer (TES) instrument on board Mars Global Surveyor (MGS), and finally (3) a brief study of the MTGCM's response to variations in upward propagating waves and tides from the lower atmosphere. Ultimately, this investigation suggests that an interhemispheric summer-to-winter Hadley circulation, originating in the lower atmosphere and extending into the upper atmosphere, is responsible for thermospheric winter polar warming [ Bell etal. , 2007]. A major branch of this thesis builds upon the previous work of Müller-Wodarg et al. [2000], Müller-Wodarg et al. [2003], M7uuml;ller-Wodarg et al. [2006], and Yelle et al. [2006] as it attempts to explain the structures in Titan's upper atmosphere, between 500-1500 km. Building also upon the recent development of GITM by Ridley et al. [2006], this thesis presents a new theoretical framework, T-GITM. This model is then employed to conduct a series of numerical experiments to quantify the impacts of the solar cycle, the season, and the

  15. Structure and Composition of the Neutral Upper Atmosphere of Mars from the MAVEN NGIMS Investigation

    NASA Astrophysics Data System (ADS)

    Mahaffy, P. R.; Benna, M.; Yelle, R. V.; Stone, S. W.; Elrod, M. K.; Fox, J. L.

    2015-12-01

    The Neutral Gas and Ion Mass Spectrometer (NGIMS) on the MAVEN mission is designed to characterize the state of the upper atmosphere and its response to perturbations from the sun and from lower atmosphere. These measurements complement other instruments on the MAVEN spacecraft and support the MAVEN science goal [Jakosky et al., 2015] of understanding atmospheric escape and over the course of martian history. We report NGIMS measurements of the neutral composition of multiple atomic and molecular species over hundreds of orbits since the science phase of this mission began late in 2014. Ion measurements from NGIMS are reported separately in other contributions to this session. The wide dynamic range, the high temporal resolution, and the use of two different ion source configurations of the NGIMS instrument [Mahaffy et al., 2014] allows neutral density structure and its variability to be characterized in detail. Large amplitude wave structure is observed on the lowest altitude portion of many orbits that dissipates at higher altitudes. Although this structure puts scatter in the retrieval of scale height temperatures these are nevertheless robustly secured by averaging over several orbits. The variability of the upper atmosphere temperature with latitude and local solar time is reported. The deep dip campaign approach to the homopause allows the mixing ratio of the major gases in the lower atmosphere to be measured. We compare these mixing ratios with those reported by the Sample Analysis at Mars investigation and previous Viking measurements. Jakosky, B. M., et al. (2015), The Mars Atmosphere and Volatile Evolution (MAVEN) Mission, Space Sci Rev, 21. Mahaffy, P. R., et al. (2014), The Neutral Gas and Ion Mass Spectrometer on the Mars Atmosphere and Volatile Evolution Mission, Space Sci Rev, 185, DOI: 10.1007/s11214-11014-10091-11211.

  16. Subcycled dynamics in the Spectral Community Atmosphere Model, version 4

    SciTech Connect

    Taylor, Mark; Evans, Katherine J; Hack, James J; Worley, Patrick H

    2010-01-01

    To gain computational efficiency, a split explicit time integration scheme has been implemented in the CAM spectral Eulerian dynamical core. In this scheme, already present in other dynamical core options within the Community Atmosphere Model, version 4 (CAM), the fluid dynamics portion of the model is subcycled to allow a longer time step for the parameterization schemes. The physics parameterization of CAM is not subject to the stability restrictions of the fluid dynamics, and thus finer spatial resolutions of the model do not require the physics time step to be reduced. A brief outline of the subcycling algorithm implementation and resulting model efficiency improvement is presented. A discussion regarding the effect of the climate statistics derived from short model runs is provided.

  17. Subtropical middle atmosphere dynamics observed by the Chung Li radar

    NASA Technical Reports Server (NTRS)

    Fu, I. J.; Liu, C. H.; Roettger, J.; Chao, J. K.

    1989-01-01

    The Chung Li Radar (24.91 N; 121.24 E) has been operating since 1986. A five beam observational configuration was used on a regular basis to study the various dynamics processes in the atmosphere-lower stratosphere height region. Due to its geographical location, the annual Typhoon and Mei-Yu seasons provide good opportunities to study the various interesting dynamic processes such as instabilities, generation of gravity waves, wave mean field interaction, etc. Three dimensional air motions due to these fronts are presented. Special cases of gravity wave generation, propagation and their effects on the turbulent layers are discussed.

  18. Dynamic Ocean-Atmosphere Coupling: A Thermostat for the Tropics

    PubMed

    Sun; Liu

    1996-05-24

    The ocean currents connecting the western tropical Pacific Ocean with the eastern tropical Pacific Ocean are driven by surface winds. The surface winds are in turn driven by the sea-surface temperature (SST) differences between these two regions. This dynamic coupling between the atmosphere and ocean may limit the SST in the tropical Pacific Ocean to below 305 kelvin even in the absence of cloud feedbacks.

  19. Spectroscopic, Kinetic, and Dynamic Experiments on Atmospheric Species.

    DTIC Science & Technology

    1985-03-21

    0077 PHYSICAL SCIENCES RESEARCH PAPERS , NO. 668 P D-A 162 691 Spectroscopic, Kinetic, and Dynamic Experiments on Atmospheric Species S. M. MILLER J. I...we observed, in a very limited data base , values similar to those predicted by the theory of Billingsley4 over the range 4 ! v’ :- 12. This result is...the identities of several others. Further investigations will be aided by an improved data base under conditions similar to those in Figure 9, with

  20. Spin dynamics in driven composite multiferroics

    SciTech Connect

    Wang, Zidong Grimson, Malcolm J.

    2015-09-28

    A spin dynamics approach has been used to study the behavior of the magnetic spins and the electric pseudo-spins in a 1-D composite multiferroic chain with a linear magneto-electric coupling at the interface. The response is investigated with either external magnetic or electric fields driving the system. The spin dynamics is based on the Landau-Lifshitz-Gilbert equation. A Gaussian white noise is later added into the dynamic process to include the thermal effects. The interface requires a closer inspection of the magneto-electric effects. Thus, we construct a 2-D ladder model to describe the behavior of the magnetic spins and the electric pseudo-spins with different magneto-electric couplings.

  1. Goddard Atmospheric Composition Data Center: Aura Data and Services in One Place

    NASA Technical Reports Server (NTRS)

    Leptoukh, G.; Kempler, S.; Gerasimov, I.; Ahmad, S.; Johnson, J.

    2005-01-01

    The Goddard Atmospheric Composition Data and Information Services Center (AC-DISC) is a portal to the Atmospheric Composition specific, user driven, multi-sensor, on-line, easy access archive and distribution system employing data analysis and visualization, data mining, and other user requested techniques for the better science data usage. It provides convenient access to Atmospheric Composition data and information from various remote-sensing missions, from TOMS, UARS, MODIS, and AIRS, to the most recent data from Aura OMI, MLS, HIRDLS (once these datasets are released to the public), as well as Atmospheric Composition datasets residing at other remote archive site.

  2. Exploring the Frontier of Exoplanet Atmosphere Dynamics with NASA's Great Observatories

    NASA Astrophysics Data System (ADS)

    Kreidberg, Laura; Bean, Jacob; Stevenson, Kevin; Showman, Adam; Fortney, Jonathan; Line, Michael; Desert, Jean-Michel

    2014-12-01

    We propose a joint Spitzer+HST program to explore the frontier of exoplanet atmosphere dynamics. We will pursue a multi-wavelength approach to create detailed maps of the thermal structure of two of the best target hot Jupiters. First, we will perform secondary eclipse mapping for WASP-18b with Spitzer at 4.5 microns to complement existing Spitzer+HST phase curve observations. The combination of these data will yield the first ever map of an exoplanet's thermal structure as a function of latitude, longitude, and altitude, and provide a benchmark for 3D atmospheric circulation models of highly irradiated planets. Second, we will use a new technique pioneered by our team to observe full-orbit phase curves for WASP-103b with Spitzer and HST/WFC3. These observations will reveal the planet's phase-resolved emission spectrum and determine the global temperature-pressure profile and atmospheric composition, as well as its heat redistribution and Bond albedo. This program will significantly expand the sample of thoroughly characterized exoplanets and enable comparative planetology beyond the Solar System. Spitzer and HST are the facilities that have made the strongest contributions to our understanding of exoplanet atmospheres thus far, and we are now in a position to combine their powers in a strategic way to yield unprecedentedly detailed characterization of hot Jupiter atmospheric dynamics. This program will set the stage for even more precise investigations that will be possible with JWST.

  3. Composition of Atmospheric Dust from Qatar in the Arabian Gulf

    NASA Astrophysics Data System (ADS)

    Yigiterhan, O.; Al-Ansari, I. S.; Abdel-Moati, M.; Al-Ansi, M.; Paul, B.; Nelson, A.; Turner, J.; Murray, J. W.; Alfoldy, B. Z.; Mahfouz, M. M. K.; Giamberini, M.

    2015-12-01

    Samples of atmospheric dust from Qatar have been collected and analyzed for major and trace elemental composition. Twenty-one samples were collected in 2014 and 2015 from Doha, Al Khor, Katara, Sealine, and Al Waab by a variety of techniques. Some samples were collected during the megastorms that occurred in April 2015. Back trajectories were determined for each sample using the NOAA HYSPLIT model over a 50 hour time interval. Our samples were about equally divided between northerly (n=12; northern Saudi Arabia, Kuwait or Iraq) and southerly (n=8; SE Saudi Arabia, United Arab Emirates and Oman) sources. One sample originated directly westward, in Saudi Arabia. Samples were microwave-assisted total acid digested (HF+HCl+HNO3) and analyzed by inductively coupled plasma-mass spectroscopy (ICP-MS) and inductively coupled plasma-optical emission spectroscopy (ICP-OES). There are only 12 out of 23 elements for which the Qatari dust was enriched relative to upper continental crust (UCC). Calcium was especially enriched at 400% relative to UCC. About 33% of the total sample mass was CaCO3, reflecting the composition of surface rocks in the source areas. Of the elements typically associated with anthropogenic activity, Ag, Ni and Zn were the most enriched relative to UCC, with enrichment factors of 182%, 233% and 209%, respectively. Others like Pb and V were not significantly enriched, with enrichment factors of 25% and 3%, respectively. The major elements Al, Mn and Fe were depleted relative to UCC because of the strong enrichment in CaCO3, with enrichment factors of -58%, -35% and -45% respectively. We separately averaged the samples with northern and southern origins to see if composition could be used to identify source. Only three elements had a statistical difference. Pb and Na were higher in the samples from the Se while Cr was higher in those from the north.

  4. Large Deformation Dynamic Bending of Composite Beams

    NASA Technical Reports Server (NTRS)

    Derian, E. J.; Hyer, M. W.

    1986-01-01

    Studies were conducted on the large deformation response of composite beams subjected to a dynamic axial load. The beams were loaded with a moderate eccentricity to promote bending. The study was primarily experimental but some finite element results were obtained. Both the deformation and the failure of the beams were of interest. The static response of the beams was also studied to determine potential differences between the static and dynamic failure. Twelve different laminate types were tested. The beams tested were 23 in. by 2 in. and generally 30 plies thick. The beams were loaded dynamically with a gravity-driven impactor traveling at 19.6 ft/sec and quasi-static tests were conducted on identical beams in a displacement controlled manner. For laminates of practical interest, the failure modes under static and dynamic loadings were identical. Failure in most of the laminate types occurred in a single event involving 40% to 50% of the plies. However, failure in laminates with 300 or 150 off-axis plies occurred in several events. All laminates exhibited bimodular elastic properties. The compressive flexural moduli in some laminates was measured to be 1/2 the tensile flexural modulus. No simple relationship could be found among the measured ultimate failure strains of the different laminate types. Using empirically determined flexural properties, a finite element analysis was reasonably accurate in predicting the static and dynamic deformation response.

  5. Large Deformation Dynamic Bending of Composite Beams

    NASA Technical Reports Server (NTRS)

    Derian, E. J.; Hyer, M. W.

    1986-01-01

    Studies were conducted on the large deformation response of composite beams subjected to a dynamic axial load. The beams were loaded with a moderate eccentricity to promote bending. The study was primarily experimental but some finite element results were obtained. Both the deformation and the failure of the beams were of interest. The static response of the beams was also studied to determine potential differences between the static and dynamic failure. Twelve different laminate types were tested. The beams were loaded dynamically with a gravity driven impactor traveling at 19.6 ft/sec and quasi-static tests were conducted on identical beams in a displacement controlled manner. For laminates of practical interest, the failure modes under static and dynamic loadings were identical. Failure in most of the laminate types occurred in a single event involving 40% to 50% of the plies. However, failure in laminates with 30 deg or 15 deg off-axis plies occured in several events. All laminates exhibited bimodular elastic properties. Using empirically determined flexural properties, a finite element analysis was reasonably accurate in predicting the static and dynamic deformation response.

  6. Simulation of all-scale atmospheric dynamics on unstructured meshes

    NASA Astrophysics Data System (ADS)

    Smolarkiewicz, Piotr K.; Szmelter, Joanna; Xiao, Feng

    2016-10-01

    The advance of massively parallel computing in the nineteen nineties and beyond encouraged finer grid intervals in numerical weather-prediction models. This has improved resolution of weather systems and enhanced the accuracy of forecasts, while setting the trend for development of unified all-scale atmospheric models. This paper first outlines the historical background to a wide range of numerical methods advanced in the process. Next, the trend is illustrated with a technical review of a versatile nonoscillatory forward-in-time finite-volume (NFTFV) approach, proven effective in simulations of atmospheric flows from small-scale dynamics to global circulations and climate. The outlined approach exploits the synergy of two specific ingredients: the MPDATA methods for the simulation of fluid flows based on the sign-preserving properties of upstream differencing; and the flexible finite-volume median-dual unstructured-mesh discretisation of the spatial differential operators comprising PDEs of atmospheric dynamics. The paper consolidates the concepts leading to a family of generalised nonhydrostatic NFTFV flow solvers that include soundproof PDEs of incompressible Boussinesq, anelastic and pseudo-incompressible systems, common in large-eddy simulation of small- and meso-scale dynamics, as well as all-scale compressible Euler equations. Such a framework naturally extends predictive skills of large-eddy simulation to the global atmosphere, providing a bottom-up alternative to the reverse approach pursued in the weather-prediction models. Theoretical considerations are substantiated by calculations attesting to the versatility and efficacy of the NFTFV approach. Some prospective developments are also discussed.

  7. The Sentinel-4 Mission: Instrument Description and Atmospheric Composition Products

    NASA Astrophysics Data System (ADS)

    Veihelmann, Ben; Meijer, Yasjka; Ingmann, Paul; Koopman, Rob; Bazalgette Courrèges-Lacoste, Grégory; Stark, Hendrik

    2013-04-01

    The Sentinel-4 mission, together with Sentinel-5 and the Sentinel-5 Precursor missions, is part of the Global Monitoring for Environment and Security (GMES) space component covering the Earth's atmosphere. The primary objective of the Sentinel-4 mission is the observation of the diurnal cycle of tropospheric species in support of the air quality applications of GMES Atmosphere Services. The presentation focuses on the Sentinel-4/UVN instrument and its related Level-2 atmospheric composition products. The Sentinel-4 instrument is an Ultra-violet Visible Near infrared spectrometer (S4/UVN) which is embarked on the geostationary Meteosat Third Generation-Sounder (MTG-S) platforms. Key features of the S4/UVN instrument are the spectral range from 305 nm to 500 nm with a spectral resolution of 0.5 nm, and from 750 nm to 775 nm with a spectral resolution of 0.12 nm, in combination with a low polarization sensitivity and a high radiometric accuracy. The instrument shall observe Europe with a revisit time of one hour. The spatial sampling distance varies across the geographic coverage area and takes a value of 8 km at a reference location at 45˚ N. The expected launch date of the first MTG-S platform is 2019, and the expected lifetime is 15 years (two S4/UVN instruments in sequence on two MTG-S platforms). ESA will develop products based on the S4/UVN measurements for the key target species, which are NO2, O3, HCHO, SO2, aerosols, and CHOCHO, and for cloud and surface properties (mainly intermediate products). Also a synergetic O3 vertical profile product is foreseen based on observations from the S4/UVN and the MTG InfraRed Sounder (IRS) on-board the same platform. Synergetic aerosol and cloud products are foreseen based on observations from the S4/UVN and from the MTG Flexible Combined Imager (FCI) on-board the MTG-Imager (MTG-I) platform. Current pre-development studies are dedicated to a daily surface reflectance map product that treats the surface directionality as

  8. The influence of leaf-atmosphere NH3(g ) exchange on the isotopic composition of nitrogen in plants and the atmosphere.

    PubMed

    Johnson, Jennifer E; Berry, Joseph A

    2013-10-01

    The distribution of nitrogen isotopes in the biosphere has the potential to offer insights into the past, present and future of the nitrogen cycle, but it is challenging to unravel the processes controlling patterns of mixing and fractionation. We present a mathematical model describing a previously overlooked process: nitrogen isotope fractionation during leaf-atmosphere NH3(g ) exchange. The model predicts that when leaf-atmosphere exchange of NH3(g ) occurs in a closed system, the atmospheric reservoir of NH3(g ) equilibrates at a concentration equal to the ammonia compensation point and an isotopic composition 8.1‰ lighter than nitrogen in protein. In an open system, when atmospheric concentrations of NH3(g ) fall below or rise above the compensation point, protein can be isotopically enriched by net efflux of NH3(g ) or depleted by net uptake. Comparison of model output with existing measurements in the literature suggests that this process contributes to variation in the isotopic composition of nitrogen in plants as well as NH3(g ) in the atmosphere, and should be considered in future analyses of nitrogen isotope circulation. The matrix-based modelling approach that is introduced may be useful for quantifying isotope dynamics in other complex systems that can be described by first-order kinetics.

  9. Composition of LHB Comets and Their Influence on the Early Earth Atmosphere Composition

    NASA Technical Reports Server (NTRS)

    Tornow, C.; Kupper, S.; Ilgner, M.; Kuehrt, E.; Motschmann, U.

    2011-01-01

    Two main processes were responsible for the composition of this atmosphere: chemical evolution of the volatile fraction of the accretion material forming the planet and the delivery of gasses to the planetary surface by impactors during the late heavy bombardment (LHB). The amount and composition of the volatile fraction influences the outgassing of the Earth mantle during the last planetary formation period. A very weakened form of outgassing activity can still be observed today by examining the composition of volcanic gasses. An enlightenment of the second process is based on the sparse records of the LHB impactors resulting from the composition of meteorites, observed cometary comas, and the impact material found on the Moon. However, for an assessment of the influence of the outgassing on the one hand and the LHB event on the other, one has to supplement the observations with numerical simulations of the formation of volatiles and their incorporation into the accretion material which is the precursors of planetary matter, comets and asteroids. These simulations are performed with a combined hydrodynamic-chemical model of the solar nebula (SN). We calculate the chemical composition of the gas and dust phase of the SN. From these data, we draw conclusions on the upper limits of the water content and the amount of carbon and nitrogen rich volatiles incorporated later into the accretion material. Knowing these limits we determine the portion of major gas compounds delivered during the LHB and compare it with the related quantities of the outgassed species.

  10. Surface Composition of Mars: Results from a New Atmospheric Compensation Technique Applied to TES

    NASA Technical Reports Server (NTRS)

    Kirkland, L. E.; Herr, K. C.; Ward, J.; Keim, E. R.; Hackwell, J. H.; McAfee, J. M.

    2002-01-01

    Before TES (Thermal Emission Spectrometry) spectra can be used to model surface compositions, they must have a strong atmospheric compensation applied. We explore a very different atmospheric retrieval process, and compare results and implications for the derived surface composition. Additional information is contained in the original extended abstract.

  11. Voyager infrared observations of Uranus' atmosphere - Thermal structure and dynamics

    NASA Astrophysics Data System (ADS)

    Flasar, F. M.; Conrath, B. J.; Pirraglia, J. A.; Gierasch, P. J.

    1987-12-01

    Temperatures in the Uranus atmosphere are derived from infrared spectrometer (IRIS) observations for a layer between 60 and 200 mbar, which includes the tropopause, where the vertical profile of temperature has a minimum. The variation with latitude of these temperatures and the implied thermal winds are in the same sense as those previously reported at the lower altitude range. The authors discuss the implications of this for dynamical models of the atmospheric thermal and wind structure. Finally, they use a linear, zonally symmetric model with radiative damping and frictional drag to estimate the magnitude of the frictional damping that is needed to account for the tropopause temperatures derived from IRIS observations and the zonal winds inferred from Voyager imaging data.

  12. Atmospheric pressure plasma assisted calcination of composite submicron fibers

    NASA Astrophysics Data System (ADS)

    Medvecká, Veronika; Kováčik, Dušan; Tučeková, Zlata; Zahoranová, Anna; Černák, Mirko

    2016-08-01

    The plasma assisted calcination of composite organic/inorganic submicron fibers for the preparation of inorganic fibers in submicron scale was studied. Aluminium butoxide/polyvinylpyrrolidone fibers prepared by electrospinning were treated using low-temperature plasma generated by special type of dielectric barrier discharge, so called diffuse coplanar surface barrier discharge (DCSBD) at atmospheric pressure in ambient air, synthetic air, oxygen and nitrogen. Effect of plasma treatment on base polymer removal was investigated by using Attenuated total reflectance - Fourier transform infrared (ATR-FTIR) spectroscopy. Influence of working gas on the base polymer reduction was studied by energy-dispersive X-ray spectroscopy (EDX) and CHNS elemental analysis. Changes in fibers morphology were observed by scanning electron microscopy (SEM). High efficiency of organic template removal without any degradation of fibers was observed after plasma treatment in ambient air. Due to the low-temperature approach and short exposure time, the plasma assisted calcination is a promising alternative to the conventional thermal calcination. Contribution to the topical issue "6th Central European Symposium on Plasma Chemistry (CESPC-6)", edited by Nicolas Gherardi, Ester Marotta and Cristina Paradisi

  13. Wave Dynamical Coupling of Atmospheres During Sudden Stratospheric Warming Events

    NASA Astrophysics Data System (ADS)

    Laskar, F. I.; Duggirala, P. R.

    2015-12-01

    The electrodynamic and neutral dynamic behavior of the low-latitude upper atmosphere during sudden stratospheric warming (SSW) events has been investigated. The equatorial electrojet (EEJ) strength and the total electron content (TEC) data from low latitudes, over Indian longitudes, during the mid-winter season in the years 2005 to 2013 are used in this study. Five major and three minor SSW events occurred in the observation duration, wherein the solar activity had varied from minimum (almost no sunspots) to mini-maximum (approximately 50 sunspots of the solar cycle 24). Spectral powers of the quasi-16-day waves in the EEJ and the TEC have been found to be dominant and varying with solar activity and SSW strengths. Specifically, the spectral powers of quasi-16-day type variations during the three dramatic strong SSW events in the years 2006, 2009, and 2013 were found to be very high in comparison with those of other years. For these major events, the amplitudes of the semi-diurnal tides and quasi-16-day waves were found to be highly correlated and were maximum around the peak of SSW, suggesting a strong interaction between the two waves. However, this correlation was poor and the quasi-16-day spectral power was low for the minor events. A strong vertical coupling of atmospheres was noted in spite of the solar activity being relatively higher during 2013, which was, however, explained to be due to the occurrence of a strong SSW event. These results suggest that the wave dynamical vertical coupling of atmospheres is stronger during strong major SSW events and weaker during minor events. Also, SSW events play an important role in enabling the upward coupling of atmospheres even during high solar activity.

  14. Satellite Observations for Detecting and Tracking Changes in Atmospheric Composition

    EPA Science Inventory

    The international scientific community's Integrated Global Atmosphere Chemistry Observation System report outlined a plan for ground-based, airborne and satellite Measurements, and models to integrate the observations into a 4-dimensional representation of the atmosphere (space a...

  15. Study of the dynamics of meteoroids through the Earth's atmosphere and retrieval of meteorites

    NASA Astrophysics Data System (ADS)

    Guadalupe Cordero Tercero, Maria; Farah-Simon, Alejandro; Velázquez-Villegas, Fernando

    2016-07-01

    When a comet , asteroid or meteoroid impact with a planet several things can happen depending on the mass, velocity and composition of the impactor, if the planet or moon has an atmosphere or not, and the angle of impact. On bodies without an atmosphere like Mercury or the Moon, every object that strikes their surfaces produces impact craters with sizes ranging from centimeters to hundreds and even thousands of kilometers across. On bodies with an atmosphere, this encounter can produce impact craters, meteorites, meteors and fragmentation. Each and every one of these phenomena is interesting because they provide information about the surfaces and the geological evolution of solar system bodies. Meteors (shooting stars) are luminous wakes on the sky due to the interaction between the meteoroid and the Earth's atmosphere. A meteoroid is asteroidal or cometary material ranging in size from 2 mm to a few tens of meters. The smallest tend to evaporate at heights between 80 and 120 km. Objects of less than 2 mm are called micrometeorites. If the meteor brightness exceeds the brightness of Venus, the phenomenon is called a bolide or fireball. If a meteoroid, or a fragment of it, survives atmospheric ablation and it can be recovered on the ground, that piece is called a meteorite. Most meteoroids 2 meters long fragment suddenly into the atmosphere, it produces a shock wave that can affect humans and their environment like the Chelyabinsk event occurred on February 15, 2013 an two less energetic events in Mexico in 2010 and 2011. To understand the whole phenomenon, we proposed a video camera network for observing meteors. The objectives of this network are to: a) contribute to the study of the fragmentation of meteoroids in the Earth's atmosphere, b) determine values of important physical parameters; c ) study seismic waves produced by atmospheric shock waves, d) study the dynamics of meteoroids and f ) recover and study meteorites. During this meeting, the academic

  16. LWS FST: Determine and Quantify the Responses of Atmospheric/Ionospheric Composition and Temperature to Solar XUV Spectral Variability

    NASA Astrophysics Data System (ADS)

    Talaat, E. R.; Fuller-Rowell, T. J.; Qian, L.; Richards, P. G.; Ridley, A. J.

    2010-12-01

    We present a summary of the research plans and preliminary results of our 2009 Living With a Star Focus Science Team. Focus Area Description: With the recent availability of comprehensive solar spectral measurements at X-ray and ultraviolet (XUV) wavelengths, together with upper atmospheric chemistry and transport models, quantification of the full range of solar effects on chemically active minor constituents and ion composition in the ionospherethermosphere- mesosphere (I-T-M) system is now possible. Additional solar-driven variation is caused by the energetic particle environment, ranging from auroral fluxes to galactic cosmic rays. These sources have important influences on the chemistry, energetics, and dynamics of the lower thermosphere and ionosphere (e.g., on nitric oxide and ozone) via direct energy deposition and modulation of ion-neutral frictional heating. Observations of neutral composition and temperature for different phases of the solar cycle and for sporadic events are available through NASA missions like the Upper Atmosphere Research Satellite (UARS) and the Thermosphere Ionosphere Mesosphere Energetics and Dynamics mission (TIMED), as well as from other space- and groundbased instruments. Observations of ionospheric electron density are available through a variety of sources. In view of these advances, models of atmospheric/ionospheric composition and energetics that fully exploit the available estimates of external energetic inputs can now be developed to more accurately quantify solar effects in the middle and upper atmosphere. We seek to determine how well our understanding of atmospheric/ionospheric processes, as incorporated in state-of-the-art models, is able to explain observed compositional and temperature effects in the middle and upper atmosphere caused by external energetic inputs, in order to be able to predict these effects under both normal and extreme conditions.

  17. ATMOSPHERIC DYNAMICS OF BROWN DWARFS AND DIRECTLY IMAGED GIANT PLANETS

    SciTech Connect

    Showman, Adam P.; Kaspi, Yohai

    2013-10-20

    A variety of observations provide evidence for vigorous motion in the atmospheres of brown dwarfs and directly imaged giant planets. Motivated by these observations, we examine the dynamical regime of the circulation in the atmospheres and interiors of these objects. Brown dwarfs rotate rapidly, and for plausible wind speeds, the flow at large scales will be rotationally dominated. We present three-dimensional, global, numerical simulations of convection in the interior, which demonstrate that at large scales, the convection aligns in the direction parallel to the rotation axis. Convection occurs more efficiently at high latitudes than low latitudes, leading to systematic equator-to-pole temperature differences that may reach ∼1 K near the top of the convection zone. The interaction of convection with the overlying, stably stratified atmosphere will generate a wealth of atmospheric waves, and we argue that, as in the stratospheres of planets in the solar system, the interaction of these waves with the mean flow will cause a significant atmospheric circulation at regional to global scales. At large scales, this should consist of stratified turbulence (possibly organizing into coherent structures such as vortices and jets) and an accompanying overturning circulation. We present an approximate analytic theory of this circulation, which predicts characteristic horizontal temperature variations of several to ∼50 K, horizontal wind speeds of ∼10-300 m s{sup –1}, and vertical velocities that advect air over a scale height in ∼10{sup 5}-10{sup 6} s. This vertical mixing may help to explain the chemical disequilibrium observed on some brown dwarfs. Moreover, the implied large-scale organization of temperature perturbations and vertical velocities suggests that near the L/T transition, patchy clouds can form near the photosphere, helping to explain recent observations of brown-dwarf variability in the near-IR.

  18. Experiments of reconstructing discrete atmospheric dynamic models from data (I)

    NASA Astrophysics Data System (ADS)

    Lin, Zhenshan; Zhu, Yanyu; Deng, Ziwang

    1995-03-01

    In this paper, we give some experimental results of our study in reconstructing discrete atmospheric dynamic models from data. After a great deal of numerical experiments, we found that the logistic map, x n + 1 = 1- μx {2/n}, could be used in monthly mean temperature prediction when it was approaching the chaotic region, and its predictive results were in reverse states to the practical data. This means that the nonlinear developing behavior of the monthly mean temperature system is bifurcating back into the critical chaotic states from the chaotic ones.

  19. Dynamical vegetation-atmosphere modelling of the boreal zone

    NASA Astrophysics Data System (ADS)

    Tang, Hui; Stordal, Frode; Berntsen, Terje K.; Bryn, Anders

    2016-04-01

    Vegetation interacts with climate on seasonal to inter-annual time scales through albedo, roughness, evapotranspiration, CO2 sequestration and by influencing snow accumulation and ablation. The Scandinavian mountains and high latitudes is a hot spot for land-atmosphere feedback, as the future's increased winter minimum temperature supports a boreal tree line advance, lowering the surface albedo. The northern ecosystem is dominated by mires, boreal forests and alpine heaths, in addition to agricultural land. Model studies have shown that vegetation-climate feedbacks are strong enough to lead to regime shifts in vegetation and local climate in boreal regions. Biogeophysical factors, such as albedo, the Bowen ratio, and surface roughness, are all involved in these feedbacks, and they are also altered by land use change such as reforestation. For calculations of the dynamical coupling between the atmosphere and the vegetation we have used the Earth System Model NorESM, which includes several advanced features in its land surface model (CLM4.5), such as the inclusion of the radiative forcing due to black carbon and dust deposit onto snow, improved representation of fire, permafrost and its hydrological impact, a new snow cover fraction parameterization reflecting the hysteresis in fractional snow cover for a given snow depth between accumulation and melt phases, as well as dynamic vegetation coupled with carbon-nitrogen cycles. These new features improve the representation of surface albedo feedback in Arctic. We have performed experiments with coupled as well fixed ocean for the current as a quadrupled atmospheric CO2 situation. This model configuration is used to study changes in vegetation in a high end radiative forcing case. It is contrasted with an experiment where vegetation dynamics is neglected. Changes in the features of the vegetation along with surface fluxes, albedo and atmospheric temperatures are analysed, with main emphasis on the boreal zone. In

  20. Satellite-Borne Measurements of Middle-Atmosphere Composition

    NASA Astrophysics Data System (ADS)

    Russell, J. M.; McCormick, M. P.

    1987-11-01

    A number of satellite experiments have been launched in recent years with the goal of providing fundamental data needed for analysis of photochemistry, radiation, dynamics, and transport processes. Collectively, these experiments have accumulated information on the vertical and horizontal distributions of a host of minor constituents in the middle atmosphere. The combined satellite data set includes new global measurements of O3, NO2, N2O, HNO3, CH4, H2O, and aerosols, and more-limited data on CO, N2O5, ClONO2, HNO4, COF2, and CH3Cl. These data have provided descriptions of (1) the geographic extent and year-to-year change in the recently discovered Antarctic ozone hole; (2) interannual variability in N2O and CH4; (3) the winter high latitude NO2 `cliff'; (4) exchange of NO2 from the mesosphere to the stratosphere during polar night; (5) a lower limit total odd nitrogen distribution that displays a maximum that exceeds model calculated values; (6) variations in the newly discovered polar stratospheric clouds (PSCS) seen in the north and south polar regions; and (7) details of latitudinal and temporal aerosol variability. The existing satellite data set is deficient in certain key measurements including OH, HO2, H2O2, polar night N2O5, radiatively important aerosol properties, and simultaneous measurements of aerosols and gases involved in heterogeneous processes.

  1. Wake Dynamics in the Atmospheric Boundary Layer Over Complex Terrain

    NASA Astrophysics Data System (ADS)

    Markfort, Corey D.

    The goal of this research is to advance our understanding of atmospheric boundary layer processes over heterogeneous landscapes and complex terrain. The atmospheric boundary layer (ABL) is a relatively thin (˜ 1 km) turbulent layer of air near the earth's surface, in which most human activities and engineered systems are concentrated. Its dynamics are crucially important for biosphere-atmosphere couplings and for global atmospheric dynamics, with significant implications on our ability to predict and mitigate adverse impacts of land use and climate change. In models of the ABL, land surface heterogeneity is typically represented, in the context of Monin-Obukhov similarity theory, as changes in aerodynamic roughness length and surface heat and moisture fluxes. However, many real landscapes are more complex, often leading to massive boundary layer separation and wake turbulence, for which standard models fail. Trees, building clusters, and steep topography produce extensive wake regions currently not accounted for in models of the ABL. Wind turbines and wind farms also generate wakes that combine in complex ways to modify the ABL. Wind farms are covering an increasingly significant area of the globe and the effects of large wind farms must be included in regional and global scale models. Research presented in this thesis demonstrates that wakes caused by landscape heterogeneity must be included in flux parameterizations for momentum, heat, and mass (water vapor and trace gases, e.g. CO2 and CH4) in ABL simulation and prediction models in order to accurately represent land-atmosphere interactions. Accurate representation of these processes is crucial for the predictions of weather, air quality, lake processes, and ecosystems response to climate change. Objectives of the research reported in this thesis are: 1) to investigate turbulent boundary layer adjustment, turbulent transport and scalar flux in wind farms of varying configurations and develop an improved

  2. Composition of early planetary atmospheres - I. Connecting disc astrochemistry to the formation of planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Cridland, A. J.; Pudritz, R. E.; Alessi, M.

    2016-09-01

    We present a model of the early chemical composition and elemental abundances of planetary atmospheres based on the cumulative gaseous chemical species that are accreted on to planets forming by core accretion from evolving protoplanetary discs. The astrochemistry of the host disc is computed using an ionization-driven, non-equilibrium chemistry network within viscously evolving disc models. We accrete gas giant planets whose orbital evolution is controlled by planet traps using the standard core accretion model and track the chemical composition of the material that is accreted on to the protoplanet. We choose a fiducial disc model and evolve planets in three traps - water ice line, dead zone and heat transition. For a disc with a lifetime of 4.1 Myr, we produce two hot Jupiters (M = 1.43, 2.67 MJupiter, r = 0.15, 0.11 au) in the heat transition and ice line trap and one failed core (M = 0.003 MJupiter, r = 3.7 au) in the dead zone. These planets are found with mixing ratios for CO and H2O of 1.99 × 10-4 and 5.0 × 10-4, respectively, for both hot Jupiters. Additionally, for these planets we find CO2 and CH4, with mixing ratios of 1.8 × 10-6 → 9.8 × 10-10 and 1.1 × 10-8 → 2.3 × 10-10, respectively. These ranges correspond well with the mixing ratio ranges that have been inferred through the detection of emission spectra from hot Jupiters by multiple authors. We compute a carbon-to-oxygen ratio of 0.227 for the ice line planet and 0.279 for the heat transition planet. These planets accreted their gas inside the ice line, hence the sub-solar C/O.

  3. Active upper-atmosphere chemistry and dynamics from polar circulation reversal on Titan.

    PubMed

    Teanby, Nicholas A; Irwin, Patrick G J; Nixon, Conor A; de Kok, Remco; Vinatier, Sandrine; Coustenis, Athena; Sefton-Nash, Elliot; Calcutt, Simon B; Flasar, F Michael

    2012-11-29

    Saturn's moon Titan has a nitrogen atmosphere comparable to Earth's, with a surface pressure of 1.4 bar. Numerical models reproduce the tropospheric conditions very well but have trouble explaining the observed middle-atmosphere temperatures, composition and winds. The top of the middle-atmosphere circulation has been thought to lie at an altitude of 450 to 500 kilometres, where there is a layer of haze that appears to be separated from the main haze deck. This 'detached' haze was previously explained as being due to the co-location of peak haze production and the limit of dynamical transport by the circulation's upper branch. Here we report a build-up of trace gases over the south pole approximately two years after observing the 2009 post-equinox circulation reversal, from which we conclude that middle-atmosphere circulation must extend to an altitude of at least 600 kilometres. The primary drivers of this circulation are summer-hemisphere heating of haze by absorption of solar radiation and winter-hemisphere cooling due to infrared emission by haze and trace gases; our results therefore imply that these effects are important well into the thermosphere (altitudes higher than 500 kilometres). This requires both active upper-atmosphere chemistry, consistent with the detection of high-complexity molecules and ions at altitudes greater than 950 kilometres, and an alternative explanation for the detached haze, such as a transition in haze particle growth from monomers to fractal structures.

  4. Active Upper-atmosphere Chemistry and Dynamics from Polar Circulation Reversal on Titan

    NASA Technical Reports Server (NTRS)

    Teanby, Nicholas A.; Irwin, Patrick Gerard Joseph; Nixon, Conor A.; DeKok, Remco; Vinatier, Sandrine; Coustenis, Athena; Sefton-Nash, Elliot; Calcutt, Simon B.; Flasar, Michael F.

    2012-01-01

    Saturn's moon Titan has a nitrogen atmosphere comparable to Earth's, with a surface pressure of 1.4 bar. Numerical models reproduce the tropospheric conditions very well but have trouble explaining the observed middle-atmosphere temperatures, composition and winds. The top of the middle-atmosphere circulation has been thought to lie at an altitude of 450 to 500 kilometres, where there is a layer of haze that appears to be separated from the main haze deck. This 'detached' haze was previously explained as being due to the colocation of peak haze production and the limit of dynamical transport by the circulation's upper branch. Herewe report a build-up of trace gases over the south pole approximately two years after observing the 2009 post-equinox circulation reversal, from which we conclude that middle-atmosphere circulation must extend to an altitude of at least 600 kilometres. The primary drivers of this circulation are summer-hemisphere heating of haze by absorption of solar radiation and winter-hemisphere cooling due to infrared emission by haze and trace gases; our results therefore imply that these effects are important well into the thermosphere (altitudes higher than 500 kilometres). This requires both active upper-atmosphere chemistry, consistent with the detection of high-complexity molecules and ions at altitudes greater than 950 kilometres, and an alternative explanation for the detached haze, such as a transition in haze particle growth from monomers to fractal structures.

  5. Composition and dynamics of plasma in Saturn's magnetosphere.

    PubMed

    Young, D T; Berthelier, J-J; Blanc, M; Burch, J L; Bolton, S; Coates, A J; Crary, F J; Goldstein, R; Grande, M; Hill, T W; Johnson, R E; Baragiola, R A; Kelha, V; McComas, D J; Mursula, K; Sittler, E C; Svenes, K R; Szegö, K; Tanskanen, P; Thomsen, M F; Bakshi, S; Barraclough, B L; Bebesi, Z; Delapp, D; Dunlop, M W; Gosling, J T; Furman, J D; Gilbert, L K; Glenn, D; Holmlund, C; Illiano, J-M; Lewis, G R; Linder, D R; Maurice, S; McAndrews, H J; Narheim, B T; Pallier, E; Reisenfeld, D; Rymer, A M; Smith, H T; Tokar, R L; Vilppola, J; Zinsmeyer, C

    2005-02-25

    During Cassini's initial orbit, we observed a dynamic magnetosphere composed primarily of a complex mixture of water-derived atomic and molecular ions. We have identified four distinct regions characterized by differences in both bulk plasma properties and ion composition. Protons are the dominant species outside about 9 RS (where RS is the radial distance from the center of Saturn), whereas inside, the plasma consists primarily of a corotating comet-like mix of water-derived ions with approximately 3% N+. Over the A and B rings, we found an ionosphere in which O2+ and O+ are dominant, which suggests the possible existence of a layer of O2 gas similar to the atmospheres of Europa and Ganymede.

  6. Geostrophic dynamics at surfaces in the atmosphere and ocean

    NASA Astrophysics Data System (ADS)

    Tulloch, Ross

    Observed dynamics near bounding upper surfaces in the atmosphere and ocean are interpreted in terms of quasi-geostrophic theory. The quasi-geostrophic equations consist of advection of linearized potential vorticity coupled with advection of temperature at the upper and lower bounding surfaces. We show that the standard vertical finite difference formulation of 3D quasi-geostrophic flow accurately represents the flow only down to a critical horizontal scale that decreases with vertical grid spacing. To overcome this constraint, we derive a surface-modal formulation which accurately and efficiently captures both the surface dynamics due to temperature anomalies on the upper and lower boundaries, and the interior dynamics due to potential vorticity anomalies, without the need for high vertical resolution. In the atmosphere, the horizontal wavenumber spectra of wind and temperature near the tropopause have a steep -3 slope at synoptic scales and a shallow -5/3 slope at mesoscales, with a smooth transition between the two regimes from 800km to 200km. We demonstrate that when the surface temperature anomalies are resolved, quasi-geostrophic flow driven by baroclinic instability exhibits such a transition near the tropopause. The horizontal scale of transition between -3 and -5/3 slopes depends on the relative magnitudes of the mean surface temperature gradient and the mean potential vorticity gradient. In the ocean, sea surface height anomalies measured by satellite altimetry exhibit shallower spectral slopes than quasi-geostrophic theory predicts, and faster than expected westward phase propagation of sea surface height in the midlatitudes. We argue that, in some regions, the shallow spectral slopes are due to surface quasi-geostrophic dynamics, and that the westward phase propagation in the midlatitudes is indicative of a transition from a linear Rossby wave regime in the tropics to a nonlinear turbulent regime in the midlatitudes.

  7. Composition and chemistry of the Venusian atmosphere after Venus Express

    NASA Astrophysics Data System (ADS)

    Marcq, Emmanuel

    The ESA/Venus Express orbiter mission is expected to end before the end of this year (2014), and time has come to summarize its results and examine how they changed our view of this planet. Venus Express instruments (especially the spectrometers VIRTIS and SPICAV/SOIR) have been addressing numerous scientific issues since 2006, among which remote sensing of many minor species from the lower troposphere up to the mesosphere at various latitudes and local solar time, often evidencing spatial or temporal variability. In preparation of a new synthesis of our current knowledge about Venusian atmospheric chemistry and composition to be included in the Venus III book (expected to be published in 2015), we shall present an overview of the most significant updates in this domain. A non-exhaustive list of the sub-topics we would like to address is; (1) Lower tropospheric measurements: Venus Express has been able to study in detail most of the thermal infrared windows, yielding extensive night side measurements of some key minor species (CO, OCS, H_2O, HDO, SO_2) (2) Profiles at an unparalleled vertical resolution of many minor species in the lower mesosphere thanks to stellar and solar occultation techniques. (3) Spatial and temporal variability of minor species at various scales, the most striking example being SO_2 above cloud top. (4) New theoretical understanding and modeling of the interplay between the various chemical cycles (carbon, sulfur, halogens) and the condensed phase particulate matter from the clouds and hazes, based on the newest available observational constraints from Venus Express and ground-based telescopes.

  8. The Upper Atmosphere Research Satellite In-Flight Dynamics

    NASA Technical Reports Server (NTRS)

    Woodard, Stanley E.

    1997-01-01

    Upper Atmosphere Research Satellite flight data from the first 737 days after launch (September 1991) was used to investigate spacecraft disturbances and responses. The investigation included two in-flight dynamics experiments (approximately three orbits each). Orbital and configuration influences on spacecraft dynamic response were also examined. Orbital influences were due to temperature variation from crossing the Earth's terminator and variation of the solar incident energy as the orbit precessed. During the terminator crossing, the rapid ambient temperature change caused the spacecraft's two flexible appendages to experience thermal elastic bending (thermal snap). The resulting response was dependent upon the orientation of the solar array and the solar incident energy. Orbital influences were also caused by on-board and environmental disturbances and spacecraft configuration changes resulting in dynamic responses which were repeated each orbit. Configuration influences were due to solar array rotation changing spacecraft modal properties. The investigation quantified the spacecraft dynamic response produced by the solar array and high gain antenna harmonic drive disturbances. The solar array's harmonic drive output resonated two solar array modes. Friction in the solar array gear drive provided sufficient energy dissipation which prevented the solar panels from resonating catastrophically; however, the solar array vibration amplitude was excessively large. The resulting vibration had a latitude-specific pattern.

  9. Upper atmosphere research satellite program. [to study the chemistry energetics, and dynamics

    NASA Technical Reports Server (NTRS)

    Huntress, W. T., Jr.

    1978-01-01

    A satellite program to conduct research on the chemistry, energetics, and dynamics of the upper atmosphere was developed. The scientific goals of the Upper Atmospheric Research Program, the program requirements, and the approach toward meeting those requirements are outlined. An initial series of two overlapping spacecraft missions is described. Both spacecraft are launched and recovered by the STS, one in the winter of 1983 at a 56 deg inclination, and the other a year later at a 70 deg inclination. The duration of each mission is 18 months, and each carries instruments to make global measurements of the temperature, winds, composition, irradation, and radiance in the stratosphere, mesosphere, and lower thermosphere between the tropopause and 120 km altitude. The program requires a dedicated ground-based data system and a science team organization that leads to a strong interaction between the experiments and theory. The program includes supportive observations from other platforms such as rockets, balloons, and the Spacelab.

  10. Dynamic Buckling of Composite Cylindrical Shells

    NASA Astrophysics Data System (ADS)

    Cheng, Sai-Wei; Wang, Xiao-Jun

    2016-05-01

    Considering the effect of stress wave, the dynamic buckling governing equations and boundary conditions of composite cylindrical shells under axial step load are derived based on the Hamilton principle. The expression of radial displacement function along the circumferential direction is assumed since the cylindrical shell is closed. The solutions of the governing equations are obtained by the state-space technique. The determinant of the coefficient matrix must be equal to zero if the linear equations have a non-trivial solution. The relationship between the critical load and length and the influences of boundary conditions, modes, etc. on critical load are obtained by programming with MATLAB software before and after the reflection of stress wave.

  11. Dynamic mechanical analysis of fiber reinforced composites

    NASA Technical Reports Server (NTRS)

    Reed, K. E.

    1979-01-01

    Dynamic mechanical and thermal properties were determined for unidirectional epoxy/glass composites at various fiber orientation angles. Resonant frequency and relative logarithmic decrement were measured as functions of temperature. In low angle and longitudinal specimens a transition was observed above the resin glass transition temperature which was manifested mechanically as an additional damping peak and thermally as a change in the coefficient of thermal expansion. The new transition was attributed to a heterogeneous resin matrix induced by the fiber. The temperature span of the glass-rubber relaxation was found to broaden with decreasing orientation angle, reflecting the growth of fiber contribution and exhibiting behavior similar to that of Young's modulus. The change in resonant frequency through the glass transition was greatest for samples of intermediate fiber angle, demonstrating behavior similar to that of the longitudinal shear modulus.

  12. Dynamical model for light composite fermions

    NASA Astrophysics Data System (ADS)

    Derman, Emanuel

    1981-04-01

    A simple dynamical model for the internal structure of the three light lepton and quark generations (νe,e,u,d), (νμ,μ,c,s), and (ντ,τ,t,b) is proposed. Each generation is constructed of only one fundamental massive generation F=(L∘,L-,U,D) with the same (SU3)c×SU2×U1 quantum numbers as the light generations, bound to a core of one or more massive Higgs bosons H, where H is the single physical Higgs boson necessary for spontaneous symmetry breaking in the standard model. For example, e-=[L-H], μ-=[L-HH], τ-=[L-HHH]. It is shown that the known binding force due to H exchange is attractive and strong enough to produce light bound states. Dynamical calculations for the bound-state composite fermions using the Bethe-Salpeter equation, together with some phenomenological imput, suggest MH~16 TeV and MF~100 GeV. It is likely that such bound states can have properties compatible with the up to now apparently elementary appearance of known fermions, for example, their Dirac magnetic moments and absence of intergeneration radiative decays (such as μ-->eδ). Phenomenological consequences and tests of the model are discussed.

  13. Dynamical model for light composite fermions

    SciTech Connect

    Derman, E.

    1981-04-01

    A simple dynamical model for the internal structure of the three light lepton and quark generations (..nu../sub e/,e,u,d), (..nu../sub ..mu../,..mu..,c,s), and (..nu../sub tau/,tau,t,b) is proposed. Each generation is constructed of only one fundamental massive generation F=(L-italic/sup 0/,L/sup -/,U,D) with the same (SU/sub 3/)/sub c/ x SU/sub 2/ x U/sub 1/ quantum numbers as the light generations, bound to a core of one or more massive Higgs bosons H, where H is the single physical Higgs boson necessary for spontaneous symmetry breaking in the standard model. For example, e/sup -/=L/sup -/H), ..mu../sup -/=L/sup -/HH), tau/sup -/=L/sup -/HHH). It is shown that the known binding force due to H exchange is attractive and strong enough to produce light bound states. Dynamical calculations for the bound-state composite fermions using the Bethe-Salpeter equation, together with some phenomenological imput, suggest M/sub H/approx.16 TeV and M/sub F/approx.100 GeV. It is likely that such bound states can have properties compatible with the up to now apparently elementary appearance of known fermions, for example, their Dirac magnetic moments and absence of intergeneration radiative decays (such as ..mu -->..e..gamma..). Phenomenological consequences and tests of the model are discussed.

  14. Dynamics of the atmospheres of the outer planets

    NASA Technical Reports Server (NTRS)

    Gierasch, Peter J.; Conrath, Barney J.

    1992-01-01

    Current knowledge about dynamics and the thermal structure of the outer planets is reviewed with the aim of identifying important measurements which should be made in the post-Voyager era. The existence of jets and cloud bands is the puzzle that underlies all others. The discussion focuses on the particular case of Jupiter because the documentation is the most complete. It is argued that the gross dynamical parameters of the outer planetary atmospheres are the keys to their behaviors, rather than the particular specifics of radiative forcing, cloud distributions, or thermodynamic transformations. Voyager data has shown that the jet systems decay with height in the region above the visible clouds. Therefore, the highest priority must be given to establishing dynamical parameters that characterize levels within and beneath the clouds. These require the determination of the deep structure of the jets, of the density stratification, and of the horizontal density contrasts. The deep regions are not easily accessible and these measurements present challenging opportunities. Indirect inferences about the controlling processes may sometimes be possible by observing waves and other activity in the more easily accessible stratosphere.

  15. Nonlinear dynamics of the atmospheric pollutants in Mexico City

    NASA Astrophysics Data System (ADS)

    Muñoz-Diosdado, Alejandro; Barrera-Ferrer, Amilcar; Angulo-Brown, Fernando

    2014-05-01

    The atmospheric pollution in the Metropolitan Zone of Mexico City (MZMC) is a serious problem with social, economical and political consequences, in virtue that it is the region which concentrates both the greatest country population and a great part of commercial and industrial activities. According to the World Health Organization, maximum permissible concentrations of atmospheric pollutants are exceeded frequently. In the MZMC, the environmental monitoring has been limited to criteria pollutants, named in this way due to when their levels are measured in the atmosphere, they indicate in a precise way the air quality. The Automatic Atmospheric Monitoring Network monitors and registers the values of pollutants concentration in air in the MZMC. Actually, it is integrated by approximately 35 automatic-equipped remote stations, which report an every-hour register. Local and global invariant quantities have been widely used to describe the fractal properties of diverse time series. In the study of certain time series, many times it is assumed that they are monofractal, which means that they can be described only with one fractal dimension. But this hypothesis is unrealistic because a lot of time series are heterogeneous and non stationary, so their scaling properties are not the same throughout time and therefore they may require more fractal dimensions for their description. Complexity of the atmospheric pollutants dynamics suggests us to analyze its time series of hourly concentration registers with the multifractal formalism. So, in this work, air concentration time series of MZMC criteria pollutants were studied with the proposed method. The chosen pollutants to perform this analysis are ozone, sulfur dioxide, carbon monoxide, nitrogen dioxide and PM10 (particles less than 10 micrometers). We found that pollutants air concentration time series are multifractal. When we calculate the degree of multifractality for each time series we know that while more

  16. Atmospheric dynamics Research InfraStructure in Europe: The ARISE Project

    NASA Astrophysics Data System (ADS)

    Blanc, E.; Bittner, M.; Hauchecorne, A.; Ceranna, L.; Charlton-Perez, A. J.; Ripepe, M.; Evers, L.; Kvaerna, T.; Lastovicka, J.; Eliasson, L.; Crosby, N. B.; Blanc-Benon, P.; Le Pichon, A.; Marchetti, E.; Pilger, C.; Keckhut, P.; Schmidt, C.; Lee, C.; Smets, P.

    2013-12-01

    ARISE proposes to design a new infrastructure that integrates different station networks in order to provide a new "3D" image of the atmospheric dynamics from the ground up to the mesosphere with unprecedented spatio-temporal resolution. These networks are: - the International infrasound network developed for the verification of the Comprehensive nuclear Test Ban Treaty (CTBT). This system is unique by its quality for infrasound and atmospheric wave observations, - the Network for the Detection of Atmospheric Composition Changes (NDACC) which uses Lidar to measure stratospheric dynamics, - the Network for the Detection of Mesopause Changes (NDMC), dedicated to airglow layer measurements in the mesosphere, and additional complementary stations and satellite data. The infrastructure extends across Europe and outlying regions, including polar and equatorial regions. The measurements will be used to improve the parameterization of gravity waves in the stratosphere to better resolve climate models. The project also concerns civil applications related to monitoring of natural hazards as volcanoes. The presentation will highlight the first results obtained in the frame of the project.

  17. The atmospheric circulation of the super Earth GJ 1214b: Dependence on composition and metallicity

    SciTech Connect

    Kataria, T.; Showman, A. P.; Fortney, J. J.; Marley, M. S.; Freedman, R. S.

    2014-04-20

    We present three-dimensional atmospheric circulation models of GJ 1214b, a 2.7 Earth-radius, 6.5 Earth-mass super Earth detected by the MEarth survey. Here we explore the planet's circulation as a function of atmospheric metallicity and atmospheric composition, modeling atmospheres with a low mean molecular weight (MMW; i.e., H{sub 2}-dominated) and a high MMW (i.e., water- and CO{sub 2}-dominated). We find that atmospheres with a low MMW have strong day-night temperature variations at pressures above the infrared photosphere that lead to equatorial superrotation. For these atmospheres, the enhancement of atmospheric opacities with increasing metallicity lead to shallower atmospheric heating, larger day-night temperature variations, and hence stronger superrotation. In comparison, atmospheres with a high MMW have larger day-night and equator-to-pole temperature variations than low MMW atmospheres, but differences in opacity structure and energy budget lead to differences in jet structure. The circulation of a water-dominated atmosphere is dominated by equatorial superrotation, while the circulation of a CO{sub 2}-dominated atmosphere is instead dominated by high-latitude jets. By comparing emergent flux spectra and light curves for 50× solar and water-dominated compositions, we show that observations in emission can break the degeneracy in determining the atmospheric composition of GJ 1214b. The variation in opacity with wavelength for the water-dominated atmosphere leads to large phase variations within water bands and small phase variations outside of water bands. The 50× solar atmosphere, however, yields small variations within water bands and large phase variations at other characteristic wavelengths. These observations would be much less sensitive to clouds, condensates, and hazes than transit observations.

  18. Predictions of the Atmospheric Composition of GJ 1132b

    NASA Astrophysics Data System (ADS)

    Schaefer, Laura; Wordsworth, Robin D.; Berta-Thompson, Zachory; Sasselov, Dimitar

    2016-10-01

    GJ 1132b is a nearby Earth-sized exoplanet transiting an M dwarf, and is among the most highly characterizable small exoplanets currently known. In this paper, we study the interaction of a magma ocean with a water-rich atmosphere on GJ 1132b and determine that it must have begun with more than 5 wt% initial water in order to still retain a water-based atmosphere. We also determine the amount of O2 that can build up in the atmosphere as a result of hydrogen dissociation and loss. We find that the magma ocean absorbs at most ∼10% of the O2 produced, whereas more than 90% is lost to space through hydrodynamic drag. The most common outcome for GJ 1132b from our simulations is a tenuous atmosphere dominated by O2, though, for very large initial water abundances, atmospheres with several thousands of bars of O2 are possible. A substantial steam envelope would indicate either the existence of an earlier H2 envelope or low XUV flux over the system’s lifetime. A steam atmosphere would also imply the continued existence of a magma ocean on GJ 1132b. Further modeling is needed to study the evolution of CO2 or N2-rich atmospheres on GJ 1132b.

  19. The chemical composition and climatology of the earth's early atmosphere

    NASA Technical Reports Server (NTRS)

    Henderson-Sellers, A.

    1983-01-01

    The earth's climate as it relates to the evolution of life is discussed.. Seven fundamental characteristics of the early evolutionary environment are examined, including a carbon dioxide and water vapor atmosphere, atmospheric mass between 500 and 1000 mb, a global hydrosphere, lowered solar luminosity, hospitable average global temperatures, a convectively active atmosphere, and trace gases. The influence of the early earth's extensive hydrosphere on the origin of life is considered. The warming of that hydrosphere due to radiative fluxes and the greenhouse effect is examined, and the nature of the feedback between clouds and climate is addressed.

  20. Formaldehyde Concentration Dynamics of the International Space Station Cabin Atmosphere

    NASA Technical Reports Server (NTRS)

    Perry, J. L.

    2005-01-01

    Formaldehyde presents a significant challenge to maintaining cabin air quality on board crewed spacecraft. Generation sources include offgassing from a variety of non-metallic materials as well as human metabolism. Because generation sources are pervasive and human health can be affected by continual exposure to low concentrations, toxicology and air quality control engineering experts jointly identified formaldehyde as a key compound to be monitored as part the International Space Station's (ISS) environmental health monitoring and maintenance program. Data acquired from in-flight air quality monitoring methods are the basis for assessing the cabin environment's suitability for long-term habitation and monitoring the performance of passive and active controls that are in place to minimize crew exposure. Formaldehyde concentration trends and dynamics served in the ISS cabin atmosphere are reviewed implications to present and future flight operations discussed.

  1. Atmospheric structure and dynamics: the spatial and temporal domains

    NASA Astrophysics Data System (ADS)

    Harper, G. M.

    2013-05-01

    Multi-wavelength studies of M supergiants have revealed atmospheric structures with a large range of spatial and temporal scales. Focusing on Betelgeuse, these scales and their perplexing connections from the photosphere to the interstellar medium are reviewed. Of particular current interest is the dynamic origin of the ubiquitous and relatively dust-free mass loss. Is it multiple plumes of convection driven ejecta, episodic ejection of molecular reservoirs, or a more steady and uniform flow? With powerful new facilities such as the VLT and ALMA we may begin to understand the connections and answer such puzzles, but ultimately detailed studies of a sample of M supergiants will be needed to disentangle the physics from the stars' personalities.

  2. Southeast Pacific atmospheric composition and variability sampled along 20˚S during VOCALS-REx

    SciTech Connect

    Allen, G.; Kleinman, L.; Coe, H.; Clarke, A.; Bretherton, C.; Wood, R.; Abel, S. J.; Barrett, P.; Brown, P.; George, R.; Freitag, S.; McNaughton, C.; Howell, S.; Shank, L.; Kapustin, V.; Brekhovskikh, V.; Lee, Y.-N.; Springston, S.; Toniazzo, T.; Krejci, R.; Fochesatto, J.; Shaw, G.; Krecl, P.; Brooks, B.; McKeeking, G.; Bower, K. N.; Williams, P. I.; Crosier, J.; Crawford, I.; Connolly, P.; Covert, D.; Bandy, A. R.

    2011-01-10

    The VAMOS Ocean-Climate-Atmosphere-Land Regional Experiment (VOCALS-REx) was conducted from 15 October to 15 November 2008 in the South East Pacific region to investigate interactions between land, sea and atmosphere in this unique tropical eastern ocean environment and to improve the skill of global and regional models in representing the region. This study synthesises selected aircraft, ship and surface site observations from VOCALS-REx to statistically summarise and characterise the atmospheric composition and variability of the Marine Boundary Layer (MBL) and Free Troposphere (FT) along the 20{sup o} S parallel between 70{sup o} W and 85{sup o} W. Significant zonal gradients in mean MBL sub-micron aerosol particle size and composition, carbon monoxide, ozone and sulphur dioxide were seen over the campaign, with a generally more variable and polluted coastal environment and a less variable, more pristine remote maritime regime. Gradients are observed to be associated with strong gradients in cloud droplet number. The FT is often more polluted in terms of trace gases than the MBL in the mean; however increased variability in the FT composition suggests an episodic nature to elevated concentrations. This is consistent with a complex vertical interleaving of airmasses with diverse sources and hence pollutant concentrations as seen by generalised back trajectory analysis, which suggests contributions from both local and long-range sources. Furthermore, back trajectory analysis demonstrates that the observed zonal gradients both in the boundary layer and the free troposphere are characteristic of marked changes in airmass history with distance offshore - coastal boundary layer airmasses having been in recent contact with the local land surface and remote maritime airmasses having resided over ocean for in excess of ten days. Boundary layer composition to the east of 75{sup o} W was observed to be dominated by coastal emissions from sources to the west of the Andes

  3. Novel atmospheric plasma enhanced chitosan nanofiber/gauze composite wound dressings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Electrospun chitosan nanofibers were deposited onto atmospheric plasma treated cotton gauze to create a novel composite bandage with higher adhesion, better handling properties, enhanced bioactivity, and moisture management. Plasma treatment of the gauze substrate was performed to improve the durabi...

  4. Effect of Modified Atmosphere Composition on the Metabolism of Glucose by Brochothrix thermosphacta

    PubMed Central

    Pin, Carmen; García de Fernando, Gonzalo D.; Ordóñez, Juan A.

    2002-01-01

    The influence of atmosphere composition on the metabolism of Brochothrix thermosphacta was studied by analyzing the consumption of glucose and the production of ethanol, acetic and lactic acids, acetaldehyde, and diacetyl-acetoin under atmospheres containing different combinations of carbon dioxide and oxygen. When glucose was metabolized under oxygen-free atmospheres, lactic acid was one of the main end products, while under atmospheres rich in oxygen mainly acetoin-diacetyl was produced. The proportions of the total consumed glucose used for the production of acetoin (aerobic metabolism) and lactic acid (anaerobic metabolism) were used to decide whether aerobic or anaerobic metabolism predominated at a given atmosphere composition. The boundary conditions between dominantly anaerobic and aerobic metabolisms were determined by logistic regression. The metabolism of glucose by B. thermosphacta was influenced not only by the oxygen content of the atmosphere but also by the carbon dioxide content. At high CO2 percentages, glucose metabolism remained anaerobic under greater oxygen contents. PMID:12200298

  5. Effect of modified atmosphere composition on the metabolism of glucose by Brochothrix thermosphacta.

    PubMed

    Pin, Carmen; García de Fernando, Gonzalo D; Ordóñez, Juan A

    2002-09-01

    The influence of atmosphere composition on the metabolism of Brochothrix thermosphacta was studied by analyzing the consumption of glucose and the production of ethanol, acetic and lactic acids, acetaldehyde, and diacetyl-acetoin under atmospheres containing different combinations of carbon dioxide and oxygen. When glucose was metabolized under oxygen-free atmospheres, lactic acid was one of the main end products, while under atmospheres rich in oxygen mainly acetoin-diacetyl was produced. The proportions of the total consumed glucose used for the production of acetoin (aerobic metabolism) and lactic acid (anaerobic metabolism) were used to decide whether aerobic or anaerobic metabolism predominated at a given atmosphere composition. The boundary conditions between dominantly anaerobic and aerobic metabolisms were determined by logistic regression. The metabolism of glucose by B. thermosphacta was influenced not only by the oxygen content of the atmosphere but also by the carbon dioxide content. At high CO(2) percentages, glucose metabolism remained anaerobic under greater oxygen contents.

  6. Dynamics of magnetic bright points in the lower solar atmosphere

    NASA Astrophysics Data System (ADS)

    Jafarzadeh, Shahin

    2013-08-01

    In this thesis we have investigated the structure and dynamics of small-scale magnetic bright points (MBPs) in quiet, internetwork regions of the lower solar atmosphere. Such MBPs are associated with small-scale, intense (generally kG) magnetic elements. The internetwork (IN) areas cover the largest fraction of the solar surface and it has been argued that the IN may contain most of the existing unsigned magnetic flux on the surface at any given time. However, the distribution of the magnetic field's properties in the IN regions is still being debated. Thus, only recently has the presence of kG fields in the IN been confirmed of which the studied MBPs are thought to be manifestations. In addition, interaction between intense magnetic features and convective flows on the solar surface (in particular in IN areas) have been proposed to excite waves which can carry energy to the upper solar atmosphere. The properties of these waves and their contribution to the heating of the upper solar atmosphere is still unclear. Moreover, the migration of the small magnetic elements owing to the convective flows/turbulence is not known (due to, e.g., lack of high spatial and temporal resolution observations not affected by seeing). We used high spatial and temporal resolution observations, obtained by the Sunrise balloon-borne solar observatory, to address the above issues. We concentrate on the study of the smallest MBPs visible in the data; whose apparent lack of internal fine-structure facilitates their precise location and tracking in time-series of images. The analyses were performed using an algorithm we developed to identify, locate and track the MBPs as well as to determine their physical properties at any given time. These findings have implications for, e.g., our understanding of the heating mechanisms in the higher layers of the solar atmosphere, estimates of the solar magnetic flux as well as the structure of the convection flows (within a supergranule) advecting small

  7. A normal-mode approach to Jovian atmospheric dynamic

    NASA Technical Reports Server (NTRS)

    Achterberg, Richard K.; Ingersoll, Andrew P.

    1989-01-01

    A nonlinear, quasi-geostrophic, baroclinic model of Jovian atmospheric dynamics is proposed, in which vertical variations of velocity are represented by a truncated sum over a complete set of orthogonal functions obtained by a separation of variables of the linearized quasi-geostrophic potential vorticity equation. A set of equations for the time variation of the mode amplitudes in the nonlinear case is then derived. It is shown that, for a planet with a neutrally stable, fluid interior instead of a solid lower boundary, the barotropic mode represents motions in the interior, and is not affected by the baroclinic modes. One consequence of this is that a normal-mode model with one baroclinic mode is dynamically equivalent to a one-layer model with solid lower topography. It is also shown that, for motions in Jupiter's cloudy lower troposphere, the stratosphere behaves nearly as a rigid lid, so that the normal-mode is applicable to Jupiter. The accuracy of the normal-mode model for Jupiter is tested using the following simple problems: (1) forced, vertically propagating Rossby waves, using two and three baroclinic modes, and (2) baroclinic instability, using two baroclinic modes. It is found that the normal-mode model provides qualitatively correct results, even with only a very limited number of vertical degrees of freedom.

  8. Supersonic Flight Dynamics Test 2: Trajectory, Atmosphere, and Aerodynamics Reconstruction

    NASA Technical Reports Server (NTRS)

    Karlgaard, Christopher D.; O'Farrell, Clara; Ginn, Jason M.; Van Norman, John W.

    2016-01-01

    The Supersonic Flight Dynamics Test is a full-scale flight test of aerodynamic decelerator technologies developed by the Low Density Supersonic Decelerator technology demonstration project. The purpose of the project is to develop and mature aerodynamic decelerator technologies for landing large-mass payloads on the surface of Mars. The technologies include a Supersonic Inflatable Aerodynamic Decelerator and supersonic parachutes. The first Supersonic Flight Dynamics Test occurred on June 28th, 2014 at the Pacific Missile Range Facility. The purpose of this test was to validate the test architecture for future tests. The flight was a success and, in addition, was able to acquire data on the aerodynamic performance of the supersonic inflatable decelerator. The Supersonic Disksail parachute developed a tear during deployment. The second flight test occurred on June 8th, 2015, and incorporated a Supersonic Ringsail parachute which was redesigned based on data from the first flight. Again, the inflatable decelerator functioned as predicted but the parachute was damaged during deployment. This paper describes the instrumentation, analysis techniques, and acquired flight test data utilized to reconstruct the vehicle trajectory, main motor thrust, atmosphere, and aerodynamics.

  9. Supersonic Flight Dynamics Test: Trajectory, Atmosphere, and Aerodynamics Reconstruction

    NASA Technical Reports Server (NTRS)

    Kutty, Prasad; Karlgaard, Christopher D.; Blood, Eric M.; O'Farrell, Clara; Ginn, Jason M.; Shoenenberger, Mark; Dutta, Soumyo

    2015-01-01

    The Supersonic Flight Dynamics Test is a full-scale flight test of a Supersonic Inflatable Aerodynamic Decelerator, which is part of the Low Density Supersonic Decelerator technology development project. The purpose of the project is to develop and mature aerodynamic decelerator technologies for landing large mass payloads on the surface of Mars. The technologies include a Supersonic Inflatable Aerodynamic Decelerator and Supersonic Parachutes. The first Supersonic Flight Dynamics Test occurred on June 28th, 2014 at the Pacific Missile Range Facility. This test was used to validate the test architecture for future missions. The flight was a success and, in addition, was able to acquire data on the aerodynamic performance of the supersonic inflatable decelerator. This paper describes the instrumentation, analysis techniques, and acquired flight test data utilized to reconstruct the vehicle trajectory, atmosphere, and aerodynamics. The results of the reconstruction show significantly higher lofting of the trajectory, which can partially be explained by off-nominal booster motor performance. The reconstructed vehicle force and moment coefficients fall well within pre-flight predictions. A parameter identification analysis indicates that the vehicle displayed greater aerodynamic static stability than seen in pre-flight computational predictions and ballistic range tests.

  10. Dynamic Mechanical Properties of Natural Rubber/Polyaniline Composites

    NASA Astrophysics Data System (ADS)

    Najidha, S.; Predeep, P.; Saxena, N. S.

    2008-04-01

    The Dynamic Mechanical properties of polymer composite containing Natural Rubber (NR) as the matrix and polyaniline as filler has been studied. The composites were prepared by mechanical mixing in a roll mill and vulcanized in a hot press. The dynamic modulus such as tanδ, storage modulus and loss modulus of the composite were evaluated. The glass transition (Tg) temperature of the Natural Rubber phase in the composite was shifted to lower temperature indicating that the polyaniline content strongly affects the behavior of the composite. Addition of polyaniline lowered the crosslinking degree, but produced a reinforcing effect in the elastomer.

  11. Venus lower atmospheric composition - Analysis by gas chromatography

    NASA Technical Reports Server (NTRS)

    Oyama, V. I.; Carle, G. C.; Woeller, F.; Pollack, J. B.

    1979-01-01

    The first gas chromatographic analysis of the lower atmosphere of Venus is reported. Three atmospheric samples were analyzed. The third of these samples showed carbon dioxide (96.4 percent), molecular nitrogen (3.41 percent), water vapor (0.135 percent), molecular oxygen (69.3 ppm), argon (18.6 ppm), neon (4.31 ppm), and sulfur dioxide (186 ppm). The amounts of water vapor and sulfur dioxide detected are roughly compatible with the requirements of greenhouse models of the high surface temperature of Venus. The large positive gradient of sulfur dioxide, molecular oxygen, and water vapor from the cloud tops to their bottoms, as implied by Earth-based observations and these results, gives added support for the presence of major quantities of aqueous sulfuric acid in the clouds. A comparison of the inventory of inert gases found in the atmospheres of Venus, Earth, and Mars suggests that these components are due to outgassing from the planetary interiors.

  12. The atmosphere of Jupiter

    NASA Technical Reports Server (NTRS)

    Ingersoll, A. P.

    1976-01-01

    Current information on the neutral atmosphere of Jupiter is reviewed, with approximately equal emphasis on composition and thermal structure on one hand, and markings and dynamics on the other. Studies based on Pioneer 10 and 11 data are used to refine the atmospheric model. Data on the interior are reviewed for the information they provide on the deep atmosphere. The markings and dynamics are discussed with emphasis on qualitative relationships and analogies with phenomena in earth's atmosphere.

  13. Dynamics of the middle atmosphere as observed by the ARISE project

    NASA Astrophysics Data System (ADS)

    Blanc, E.

    2015-12-01

    It has been strongly demonstrated that variations in the circulation of the middle atmosphere influence weather and climate all the way to the Earth's surface. A key part of this coupling occurs through the propagation and breaking of planetary and gravity waves. However, limited observations prevent to faithfully reproduce the dynamics of the middle atmosphere in numerical weather prediction and climate models. The main challenge of the ARISE (Atmospheric dynamics InfraStructure in Europe) project is to combine existing national and international observation networks including: the International infrasound monitoring system developed for the CTBT (Comprehensive nuclear-Test-Ban Treaty) verification, the NDACC (Network for the Detection of Atmospheric Composition Changes) lidar network, European observation infrastructures at mid latitudes (OHP observatory), tropics (Maïdo observatory), high latitudes (ALOMAR and EISCAT), infrasound stations which form a dense European network and satellites. The ARISE network is unique by its coverage (polar to equatorial regions in the European longitude sector), its altitude range (from troposphere to mesosphere and ionosphere) and the involved scales both in time (from seconds to tens of years) and space (from tens of meters to thousands of kilometers). Advanced data products are produced with the scope to assimilate data in the Weather Prediction models to improve future forecasts over weeks and seasonal time scales. ARISE observations are especially relevant for the monitoring of extreme events such as thunderstorms, volcanoes, meteors and at larger scales, deep convection and stratospheric warming events for physical processes description and study of long term evolution with climate change. Among the applications, ARISE fosters integration of innovative methods for remote detection of non-instrumented volcanoes including distant eruption characterization to provide notifications with reliable confidence indices to the

  14. Topographic Influence and Atmospheric Dynamics in the Indian Wells Valley

    NASA Astrophysics Data System (ADS)

    Uher, Erich J.

    Indian Wells Valley (IWV) is home to the China Lake Naval Air Weapons Station (NAWS) whose operations necessitate regional forecasting and weather analysis relevant to aviation and plume release scenarios. In order to better understand the terrain influenced mesoscale circulations in the varied complex terrain of Indian Wells Valley surrounding Ridgecrest, four seasonal WRF simulations were analyzed using linear shallow water theory and nonlinear theory for flows over two-dimensional mountains. The goal is to better understand the relationships between atmospheric dynamical processes and the wind/thermal structure of the mesoscale at Indian Wells Valley. This will involve exploring relationships linking theoretical meteorology in complex terrain and advanced high resolution atmospheric modeling in this region. The WRF simulation results show several distinct circulations which rely on the interaction between complex terrain and the background weather conditions: 1) In calm synoptic conditions, diurnal processes guide the evolution of boundary layer stability and slope flows. 2) In periods of greatest seasonal surface heating (i.e. summer), the pressure gradient across the Sierra Nevada drives near surface westerlies across IWV. 3) In conditions with strong synoptic scale increase in stability and meridional winds across the Sierra Nevada, a downslope windstorm can develop in IWV. The downslope winds and compensatory gravity wave activity over IWV will conclude once there is a significant change in conditions aloft, or an increase in convective instability at the surface of IWV which prevents air aloft from sinking towards the surface. These results provide a better understanding of the mesoscale meteorology in this region and improve forecast and analysis for plume transport and aviation needs while also laying the groundwork for future projects managing environmental concerns in this region.

  15. Vesicle dynamics during the atmospheric entry heating of cosmic spherules

    NASA Astrophysics Data System (ADS)

    Genge, M. J.

    2017-03-01

    Cosmic spherules are unique igneous objects that form by melting due to gas drag heating during atmospheric entry heating. Vesicles are an important component of many cosmic spherules since they suggest their precursors had finite volatile contents. Vesicle abundances in spherules decrease through the series porphyritic, glassy, barred, to cryptocrystalline spherules. Anomalous hollow spherules, with large off-center vesicles occur in both porphyritic and glassy spheres. Numerical simulation of the dynamic behavior of vesicles during atmospheric flight is presented that indicates vesicles rapidly migrate due to deceleration and separate from nonporphyritic particles. Modest rotation rates of tens of radians s-1 are, however, sufficient to impede loss of vesicles and may explain the presence of small solitary vesicles in barred, cryptocrystalline and glassy spherules. Rapid rotation at spin rates of several thousand radians s-1 are required to concentrate vesicles at the rotational axis and leads to rapid growth by coalescence and either separation or retention depending on the orientation of the rotational axis. Complex rapid rotations that concentrate vesicles in the core of particles are proposed as a mechanism for the formation of hollow spherules. High vesicle contents in porphyritic spherules suggest volatile-rich precursors; however, calculation of volatile retention indicates these have lost >99.9% of volatiles to degassing prior to melting. The formation of hollow spherules, by rapid spin, necessarily implies preatmospheric rotations of several thousand radians s-1. These particles are suggested to represent immature dust, recently released from parent bodies, in which rotations have not been slowed by magnetic damping.

  16. Microbiome of the upper troposphere: species composition and prevalence, effects of tropical storms, and atmospheric implications.

    PubMed

    DeLeon-Rodriguez, Natasha; Lathem, Terry L; Rodriguez-R, Luis M; Barazesh, James M; Anderson, Bruce E; Beyersdorf, Andreas J; Ziemba, Luke D; Bergin, Michael; Nenes, Athanasios; Konstantinidis, Konstantinos T

    2013-02-12

    The composition and prevalence of microorganisms in the middle-to-upper troposphere (8-15 km altitude) and their role in aerosol-cloud-precipitation interactions represent important, unresolved questions for biological and atmospheric science. In particular, airborne microorganisms above the oceans remain essentially uncharacterized, as most work to date is restricted to samples taken near the Earth's surface. Here we report on the microbiome of low- and high-altitude air masses sampled onboard the National Aeronautics and Space Administration DC-8 platform during the 2010 Genesis and Rapid Intensification Processes campaign in the Caribbean Sea. The samples were collected in cloudy and cloud-free air masses before, during, and after two major tropical hurricanes, Earl and Karl. Quantitative PCR and microscopy revealed that viable bacterial cells represented on average around 20% of the total particles in the 0.25- to 1-μm diameter range and were at least an order of magnitude more abundant than fungal cells, suggesting that bacteria represent an important and underestimated fraction of micrometer-sized atmospheric aerosols. The samples from the two hurricanes were characterized by significantly different bacterial communities, revealing that hurricanes aerosolize a large amount of new cells. Nonetheless, 17 bacterial taxa, including taxa that are known to use C1-C4 carbon compounds present in the atmosphere, were found in all samples, indicating that these organisms possess traits that allow survival in the troposphere. The findings presented here suggest that the microbiome is a dynamic and underappreciated aspect of the upper troposphere with potentially important impacts on the hydrological cycle, clouds, and climate.

  17. Dynamic oxygenation of the early atmosphere and oceans

    NASA Astrophysics Data System (ADS)

    Lyons, Timothy W.; Planavsky, Noah J.; Reinhard, Christopher T.

    2014-05-01

    The traditional view of the oxygenation of the early atmosphere and oceans depicts irreversibly rising abundances in two large steps: one at the Great Oxidation Event (GOE) ca. 2.3-2.4 billion years ago (Ga) and another near the end of the Neoproterozoic. This talk will explore how the latest data challenge this paradigm. Recent results reveal a far more dynamic history of early oxygenation, one with both rising and falling levels, long periods of sustained low concentrations even after the GOE, complex feedback relationships that likely coupled nutrients and ocean redox, and dramatic changes tied through still-emerging cause-and-effect relationships to first-order tectonic, climatic, and evolutionary events. In the face of increasing doubt about the robustness of organic biomarker records from the Archean, researchers are increasingly reliant on inorganic geochemical proxies for the earliest records of oxygenic photosynthesis. Proxy data now suggest oxygenesis at ca. 3.0 Ga with a likelihood of local oxygen build up in the surface ocean long before the GOE, as well as low (and perhaps transient) accumulation in the atmosphere against a backdrop of mostly less than ca. 0.001% of the present atmospheric concentration. By the GOE, the balance between oxygen sources and sinks shifted in favor of persistent accumulation, although sedimentary recycling of non-mass-dependent sulfur isotope signatures allows for the possibility of rising and falling atmospheric oxygen before the GOE as traditionally defined by the sulfur isotope record. Recycling may also hinder our ability to precisely date the transition to permanent oxygen accumulation beyond trace levels. Diverse data point to a dramatic increase in biospheric oxygen following the GOE, coincident with the largest positive carbon isotope excursion in Earth history, followed by an equally dramatic drop. This decline in Earth surface redox potential ushered in more than a billion years of dominantly low oxygen levels in

  18. Optimization of the sintering atmosphere for high-density hydroxyapatite-carbon nanotube composites.

    PubMed

    White, Ashley A; Kinloch, Ian A; Windle, Alan H; Best, Serena M

    2010-10-06

    Hydroxyapatite-carbon nanotube (HA-CNT) composites have the potential for improved mechanical properties over HA for use in bone graft applications. Finding an appropriate sintering atmosphere for this composite presents a dilemma, as HA requires water in the sintering atmosphere to remain phase pure and well hydroxylated, yet CNTs oxidize at the high temperatures required for sintering. The purpose of this study was to optimize the atmosphere for sintering these composites. While the reaction between carbon and water to form carbon monoxide and hydrogen at high temperatures (known as the 'water-gas reaction') would seem to present a problem for sintering these composites, Le Chatelier's principle suggests this reaction can be suppressed by increasing the concentration of carbon monoxide and hydrogen relative to the concentration of carbon and water, so as to retain the CNTs and keep the HA's structure intact. Eight sintering atmospheres were investigated, including standard atmospheres (such as air and wet Ar), as well as atmospheres based on the water-gas reaction. It was found that sintering in an atmosphere of carbon monoxide and hydrogen, with a small amount of water added, resulted in an optimal combination of phase purity, hydroxylation, CNT retention and density.

  19. Effects of Chemical Abundances on the Structure and Dynamics of the Solar Atmosphere

    NASA Astrophysics Data System (ADS)

    Demarque, Pierre; Basu, S.; Robinson, F.; Hunter, C.; Kallinger, T.

    2008-05-01

    This paper presents a comparison between two three-dimensional radiative hydrodynamical (3D RHD) simulations of the solar outer layers using the Grevesse & Sauval (1998; GS98) and the Asplund, Grevesse & Sauval (2005; AGS05) mixtures, respectively. The AGS05 mixture is a revision of the solar abundance mixture using a model atmosphere based on the stratification and dynamics of a solar 3D RHD simulation performed with the GS98 mixture, using the code of Stein & Nordlund (1989, 1998). Our simulations use the same code, and physically realistic treatment of radiative opacities and equation of state as Robinson et al. (2003). A comparison between our GS98 and AGS05 3D simulations shows differences both in the mean vertical temperature gradient and in the turbulent velocity field in the line forming region of the solar atmosphere. The whole superadiabatic layer (SAL) in the AGS05 simulation, including its peak, is shifted outward with respect to the GS98 SAL. Turbulent velocities, critical for absorption line profile calculations, are larger in the AGS05 simulation by about 10%. Since opacities for the AGS05 mixture are lower than those for the GS98 mixture, the T-τ relations derived from the two simulations are different. At 5000K, τ obtained from the GS98 simulation is about 30% larger than that obtained from the AGS05 simulation. These results show the importance of preserving self consistency in the chemical abundances between the model atmosphere and the 3D HRD simulation. When deriving the solar abundances, one must iterate the chemical composition in the model atmosphere, and hence in the 3D simulation on which the atmosphere is based. This research was supported in part by NASA/ATP grant NAG5-13299 (PD and FR) and NSF grant ATM 0348837 to SB.

  20. Atmospheric-Pressure Processed Silver Nanowire (Ag-NW)/ZnO Composite Transparent Conducting Contacts

    SciTech Connect

    Perkins, John D.; Aggarwal, Shruti; van Hest, Maikel F. A. M.; Ginley, David S.

    2015-06-14

    Composite transparent contacts (TCs) based on metal nanowires and metal oxide matrix materials hold great promise for high performance transparent contacts for photovoltaics and opto-electronic technologies with the potential of all-atmospheric pressure processing. The metal nanowire mesh can provide both electrical conductivity and mechanical robustness against bending while the matrix material can both control the electrical interface and protect the metal nanowires. Here, we demonstrate all atmospheric pressure processed Ag-NW/ZnO composite TCs that are 90% transparent in the visible with sheet resistance Rs ~= 10 Ohms/sq. In addition, the composite TCs have higher infrared transmission than conventional TCO films with the same sheet resistance.

  1. Atmospheric composition as a potential taphonomic filter for the fossil leaf record

    NASA Astrophysics Data System (ADS)

    Bacon, Karen; Haworth, Matthew; McElwain, Jennifer

    2016-04-01

    Controlled environment chambers provide a unique opportunity to investigate plant responses to simulated palaeoatmospheric compositions that reflect previous periods of Earth history. One potentially important role of atmospheric composition that has not been considered in detail, is how it may affect plant preservation in the fossil record. Previous work has shown that plants, particularly angiosperms, have a tendency to increase leaf mass per area (LMA) when grown in above-ambient CO2. We tested the response of six nearest living equivalent taxa for Mesozoic floras to a range of simulated Mesozoic palaeoatmospheric treatments in controlled environment chambers. Exposure to high CO2 (~1,500 ppm) led to a statistically significant (p < 0.001) increase in LMA in four out of 6 species and exposure to high CO2 and low O2 (~13%) led to a statistically significant (p < 0.001) increase in LMA in all six species. These findings suggest that atmospheric composition has a highly significant impact on LMA. If this is also the case in fossil floras, then this suggests that atmospheric composition may influence leaf preservation potential in the fossil record. Based on these results, we put forward the hypothesis that atmospheric composition is an important taphonomic filter of the fossil leaf record. Further research is now required to test the significance of atmospheric composition versus other well-known taphonomic filters.

  2. Charge dynamics in ionic polymer metal composites

    NASA Astrophysics Data System (ADS)

    Porfiri, Maurizio

    2008-11-01

    In this paper, we study the charge dynamics in ionic polymer metal composites (IPMCs) in response to a voltage difference applied across their electrodes. We use the Poisson-Nernst-Planck equations to model the time evolution of the electric potential and the concentration of mobile counterions. We present an analytical solution of the nonlinear initial-boundary value problem by using matched asymptotic expansions. We determine the charge and electric potential distributions as functions of time in the whole IPMC region. We show that in the bulk polymer region the IPMC is approximately electroneutral; in contrast, charge distribution boundary layers arise at the polymer-electrode interfaces. Prominent charge depletion and enrichment at the polymer-electrode interface are present even at moderately low input-voltage levels. We use the proposed analytical solution to derive a physics-based circuit model of IPMCs. The equivalent circuit comprises a linear resistor in series connection with a nonlinear capacitor. We derive closed-form expressions for the resistance and the capacitance by conducting a qualitative phase-plane analysis of the inner approximation of the asymptotic expansion. The circuit conductivity is independent of the IPMC dielectric constant and is proportional to the ion diffusivity; whereas, the capacitance is proportional to the square root of the dielectric constant and is independent of the diffusivity. The conductivity depends on the polymer thickness, while the capacitance is independent of it. The capacitance nonlinearity is extremely pronounced, and dramatic capacitance reduction is observed for moderately low voltage levels. We validate the proposed analytical solution along with the derived circuit model through extensive comparisons with finite element results available in the technical literature.

  3. Martian atmospheric photochemistry and composition during periods of low obliquity

    NASA Astrophysics Data System (ADS)

    Lindner, B. L.; Jakosky, B. M.

    1985-04-01

    During periods of low obliquity, previous work has shown that martian CO2 partial pressures decreased to 0.1 mbar; CO2 partial pressure decreased to 0.02 mbar prior to the formation of the Tharsis bulge. The permanent polar caps act as a cold trap and projected global average water vapor abundances drop to possibly as low as 10-5 precipitable μm. As a result, the odd hydrogen catalytic cycle would not be effective at recombining CO and O back into CO2, and as much as 0.12 mbar of CO and 0.06 mbar of O2 could exist. These increased abundances would radically affect surface oxidation, change the lower atmospheric thermal structure, and completely alter the upper atmosphere.

  4. Martian atmospheric photochemistry and composition during periods of low obliquity

    NASA Technical Reports Server (NTRS)

    Lindner, B. L.; Jakosky, B. M.

    1985-01-01

    During periods of low obliquity, previous work has shown that martian CO2 partial pressures decreased to 0.1 mbar; CO2 partial pressures decreased to 0.02 mbar prior to the formation of the Tharsis bulge. The permanent polar caps act as a cold trap and projected global average water vapor abundances drop to possibly as low as 0.00001 precipitable micron. As a result, the odd hydrogen catalytic cycle would not be effective at recombining CO and O back into CO2, and as much as 0.12 mbar of CO and 0.06 mbar of O2 could exist. These increased abundances would radically affect surface oxidation, change the lower atmospheric thermal structure, and completely alter the upper atmosphere.

  5. Measurement of the atmospheric neutrino flavour composition in Soudan 2

    NASA Astrophysics Data System (ADS)

    Allison, W. W. M.; Alner, G. J.; Ayres, D. S.; Barrett, W. L.; Bode, C.; Border, P. M.; Brooks, C. B.; Cobb, J. H.; Cockerill, D. J. A.; Cotton, R. J.; Courant, H.; Demuth, D. M.; Fields, T. H.; Gallagher, H. R.; Garcia-Garcia, C.; Goodman, M. C.; Gray, R. N.; Johns, K.; Kafka, T.; Kasahara, S. M. S.; Leeson, W.; Litchfield, P. J.; Longley, N. P.; Lowe, M. J.; Mann, W. A.; Marshak, M. L.; May, E. N.; Milburn, R. H.; Miller, W. H.; Mualem, L.; Napier, A.; Oliver, W.; Pearce, G. F.; Perkins, D. H.; Peterson, E. A.; Petyt, D. A.; Price, L. E.; Roback, D. M.; Ruddick, K.; Schmid, D. J.; Schneps, J.; Schub, M. H.; Seidlein, R. V.; Shupe, M. A.; Stassinakis, A.; Sundaralingam, N.; Thomas, J.; Thron, J. L.; Vassiliev, V.; Villaume, G.; Wakely, S. P.; Wall, D.; Werkema, S. J.; West, N.; Wielgosz, U. M.

    1997-02-01

    The atmospheric neutrino flavour ratio measured using a 1.52 kton-year exposure of Soudan 2 is found to be 0.72 +/- 0.19+0.05-0.07 relative to the expected value from a Monte Carlo calculation. The possible background of interactions of neutrons and photons produced in muon interactions in the rock surrounding the detector has been investigated and is shown not to produce low values of the ratio.

  6. Dynamical characteristics of atmospheric aerosols over IG region

    NASA Astrophysics Data System (ADS)

    Sharma, Manish; Singh, Ramesh P.; Kumar, Rajesh

    2016-05-01

    The dynamical characteristics of atmospheric aerosols over the Indo-Gangetic (IG) region are primarily dependent on the geographical settings and meteorological conditions. Detailed analysis of multi satellite data and ground observations have been carried out over three different cities i.e. Kanpur, Greater Noida and Amritsar during 2010-2013. Level-3 Moderate Resolution Imaging Spectroradiometer (MODIS) terra daily global grid product with spatial resolution of 1° × 1° shows the mean AOD at 500 nm wavelength value of 0.73, 0.70 and 0.67 with the standard deviation of 0.43, 0.39 and 0.36 respectively over Amritsar, Greater Noida and Kanpur. Our detailed analysis shows characteristic behavior of aerosols from west to east in the IG region depending upon the proximity of desert regions of Arabia. We have observed large influx of dusts from the Thar desert and Arabia peninsula during pre-monsoon season (April-June), highly affecting Amritsar which is close to the desert region.

  7. COMPOSITIONAL DIVERSITY IN THE ATMOSPHERES OF HOT NEPTUNES, WITH APPLICATION TO GJ 436b

    SciTech Connect

    Moses, J. I.; Line, M. R.; Visscher, C.; Richardson, M. R.; Nettelmann, N.; Fortney, J. J.; Barman, T. S.; Stevenson, K. B.; Madhusudhan, N.

    2013-11-01

    Neptune-sized extrasolar planets that orbit relatively close to their host stars—often called {sup h}ot Neptunes{sup —}are common within the known population of exoplanets and planetary candidates. Similar to our own Uranus and Neptune, inefficient accretion of nebular gas is expected produce hot Neptunes whose masses are dominated by elements heavier than hydrogen and helium. At high atmospheric metallicities of 10-10,000 times solar, hot Neptunes will exhibit an interesting continuum of atmospheric compositions, ranging from more Neptune-like, H{sub 2}-dominated atmospheres to more Venus-like, CO{sub 2}-dominated atmospheres. We explore the predicted equilibrium and disequilibrium chemistry of generic hot Neptunes and find that the atmospheric composition varies strongly as a function of temperature and bulk atmospheric properties such as metallicity and the C/O ratio. Relatively exotic H{sub 2}O, CO, CO{sub 2}, and even O{sub 2}-dominated atmospheres are possible for hot Neptunes. We apply our models to the case of GJ 436b, where we find that a CO-rich, CH{sub 4}-poor atmosphere can be a natural consequence of a very high atmospheric metallicity. From comparisons of our results with Spitzer eclipse data for GJ 436b, we conclude that although the spectral fit from the high-metallicity forward models is not quite as good as the best fit obtained from pure retrieval methods, the atmospheric composition predicted by these forward models is more physically and chemically plausible in terms of the relative abundance of major constituents. High-metallicity atmospheres (orders of magnitude in excess of solar) should therefore be considered as a possibility for GJ 436b and other hot Neptunes.

  8. Dynamics and Predictability of Deep Propagating Atmospheric Gravity Waves

    NASA Astrophysics Data System (ADS)

    Doyle, J.; Fritts, D. C.; Smith, R.; Eckermann, S. D.

    2012-12-01

    An overview will be provided of the first field campaign that attempts to follow deeply propagating gravity waves (GWs) from their tropospheric sources to their mesospheric breakdown. The DEEP propagating gravity WAVE experiment over New Zealand (DEEPWAVE-NZ) is a comprehensive, airborne and ground-based measurement and modeling program focused on providing a new understanding of GW dynamics and impacts from the troposphere through the mesosphere and lower thermosphere (MLT). This program will employ the new NSF/NCAR GV (NGV) research aircraft from a base in New Zealand in a 6-week field measurement campaign in June-July 2014. The NGV will be equipped with new lidar and airglow instruments for the DEEPWAVE measurement program, providing temperatures and vertical winds spanning altitudes from immediately above the NGV flight altitude (~13 km) to ~100 km. The region near New Zealand is chosen since all the relevant GW sources occur strongly here, and upper-level winds in austral winter permit GWs to propagate to very high altitudes. Given large-amplitude GWs that propagate routinely into the MLT, the New Zealand region offers an ideal natural laboratory for studying these important GW dynamics and effects impacting weather and climate over a much deeper atmospheric layer than previous campaigns have attempted (0-100 km altitude). The logistics of making measurements in the vicinity of New Zealand are potentially easier than from the Andes and Drake Passage region. A suite of GW-focused modeling and predictability tools will be used to guide NGV flight planning to GW events of greatest scientific significance. These models will also drive scientific interpretation of the GW measurements, together providing answers to the key science questions posed by DEEPWAVE about GW dynamics, morphology, predictability and impacts from 0-100 km. Preliminary results will be presented from high-resolution and adjoint models applied over areas featuring deep wave propagation. The high

  9. Nonlinear Dynamic Properties of Layered Composite Materials

    SciTech Connect

    Andrianov, Igor V.; Topol, Heiko; Weichert, Dieter; Danishevs'kyy, Vladyslav V.

    2010-09-30

    We present an application of the asymptotic homogenization method to study wave propagation in a one-dimensional composite material consisting of a matrix material and coated inclusions. Physical nonlinearity is taken into account by considering the composite's components as a Murnaghan material, structural nonlinearity is caused by the bonding condition between the components.

  10. The carbon isotope composition of atmospheric CO 2 in Paris

    NASA Astrophysics Data System (ADS)

    Widory, David; Javoy, Marc

    2003-10-01

    One characteristic of air pollution in the urban environment is high CO 2 concentrations resulting from human activities. Determining the relative contributions of the different CO 2 sources can be addressed simply and elegantly by combining isotope and concentration measurements. Using this approach on atmospheric CO 2 samples collected in Paris, its suburbs and the open country provides fairly accurate conclusions. Our results show that air pollution within the first few metres above ground results basically from binary mixtures among which road traffic is the main contributor and, in particular, vehicles using unleaded gasoline (˜90% of the total). Heating sources, which account for 50% of the CO 2 input below the atmospheric inversion level, and vehicles using diesel contribute very little. Human respiration has a recognisable signature at street level under certain circumstances. The combined isotope and concentration analysis provides a sensitive tracer of local variations, even detecting the occasional prevalence of human respiration and the onset of actions in which natural gas is burnt. It also detects surprising inlets of 'clean air' (CO 2-wise) in the very centre of the city.

  11. The dynamic atmospheres of red giant stars. Spectral synthesis in high resolution

    NASA Astrophysics Data System (ADS)

    Nowotny, W.

    2005-11-01

    Light is the only source of information we have to study distant stars. Our knowledge about the state of the matter inside stars has been gathered by analysing star light (photometry, spectroscopy, interferometry, polarimetry, etc.). Of central importance in this context are stellar atmospheres, which are the transition regions from the optically thick stellar interiors where the electromagnetic radiation is generated to the optically thin outer layers from where the photons can leave the star. However, the atmosphere of a star is not only the region where most of the observable radiation is emitted or in other words the layers which are "visible from outside". The atmosphere also leaves an imprint on the stellar spectrum as the radiation passes through, most of the line spectrum is formed there. Thus, the light serves as a probe for the physical processes within stellar atmospheres, especially spectroscopy is one of the major tools in stellar astrophysics. Applying the underlying physical principles in numerical simulations (model atmospheres, synthetic spectra) is the second -- complementary and necessary -- step towards a deeper understanding of stellar atmospheres and for deriving stellar parameters (e.g. T_eff, L, log g, chemical composition) of observed objects. This thesis is dedicated to the outer layers of Asymptotic Giant Branch (AGB) stars, which have rather remarkable properties compared to atmospheres of most other types of stars. AGB stars represent low- to intermediate mass stars at a late stage of their evolution. Forming a sub-group among all red giants, they exhibit large extensions, low effective temperatures and high luminosities. The evolutionary phase of the AGB -- complex but decisive for stellar evolution -- is characterised by several important phenomena as for example nucleo-synthesis in explosively burning shells (thermal pulses), convective processes (dredge up), large-amplitude pulsations with long periods or a pronounced mass loss. Red

  12. Isothermal evaporation of ethanol in a dynamic gas atmosphere.

    PubMed

    Milev, Adriyan S; Wilson, Michael A; Kannangara, G S Kamali; Feng, Hai; Newman, Phillip A

    2012-01-12

    Optimization of evaporation and pyrolysis conditions for ethanol are important in carbon nanotube (CNT) synthesis. The activation enthalpy (ΔH(‡)), the activation entropy (ΔS(‡)), and the free energy barrier (ΔG(‡)) to evaporation have been determined by measuring the molar coefficient of evaporation, k(evap), at nine different temperatures (30-70 °C) and four gas flow rates (25-200 mL/min) using nitrogen and argon as carrier gases. At 70 °C in argon, the effect of the gas flow rate on k(evap) and ΔG(‡) is small. However, this is not true at temperatures as low as 30 °C, where the increase of the gas flow rate from 25 to 200 mL/min results in a nearly 6 times increase of k(evap) and decrease of ΔG(‡) by ~5 kJ/mol. Therefore, at 30 °C, the effect of the gas flow rate on the ethanol evaporation rate is attributed to interactions of ethanol with argon molecules. This is supported by simultaneous infrared spectroscopic analysis of the evolved vapors, which demonstrates the presence of different amounts of linear and cyclic hydrogen bonded ethanol aggregates. While the amount of these aggregates at 30 °C depends upon the gas flow rate, no such dependence was observed during evaporation at 70 °C. When the evaporation was carried out in nitrogen, ΔG(‡) was almost independent of the evaporation temperature (30-70 °C) and the gas flow rate (25-200 mL/min). Thus the evaporation of ethanol in a dynamic gas atmosphere at different temperatures may go via different mechanisms depending on the nature of the carrier gas.

  13. Transport composite fuselage technology: Impact dynamics and acoustic transmission

    NASA Technical Reports Server (NTRS)

    Jackson, A. C.; Balena, F. J.; Labarge, W. L.; Pei, G.; Pitman, W. A.; Wittlin, G.

    1986-01-01

    A program was performed to develop and demonstrate the impact dynamics and acoustic transmission technology for a composite fuselage which meets the design requirements of a 1990 large transport aircraft without substantial weight and cost penalties. The program developed the analytical methodology for the prediction of acoustic transmission behavior of advanced composite stiffened shell structures. The methodology predicted that the interior noise level in a composite fuselage due to turbulent boundary layer will be less than in a comparable aluminum fuselage. The verification of these analyses will be performed by NASA Langley Research Center using a composite fuselage shell fabricated by filament winding. The program also developed analytical methodology for the prediction of the impact dynamics behavior of lower fuselage structure constructed with composite materials. Development tests were performed to demonstrate that the composite structure designed to the same operating load requirement can have at least the same energy absorption capability as aluminum structure.

  14. Radiolytic Model for Chemical Composition of Europa's Atmosphere and Surface

    NASA Technical Reports Server (NTRS)

    Cooper, John F.

    2004-01-01

    The overall objective of the present effort is to produce models for major and selected minor components of Europa s neutral atmosphere in 1-D versus altitude and in 2-D versus altitude and longitude or latitude. A 3-D model versus all three coordinates (alt, long, lat) will be studied but development on this is at present limited by computing facilities available to the investigation team. In this first year we have focused on 1-D modeling with Co-I Valery Shematovich s Direct Simulation Monte Carlo (DSMC) code for water group species (H2O, O2, O, OH) and on 2-D with Co-I Mau Wong's version of a similar code for O2, O, CO, CO2, and Na. Surface source rates of H2O and O2 from sputtering and radiolysis are used in the 1-D model, while observations for CO2 at the Europa surface and Na detected in a neutral cloud ejected from Europa are used, along with the O2 sputtering rate, to constrain source rates in the 2-D version. With these separate approaches we are investigating a range of processes important to eventual implementation of a comprehensive 3-D atmospheric model which could be used to understand present observations and develop science requirements for future observations, e.g. from Earth and in Europa orbit. Within the second year we expect to merge the full water group calculations into the 2-D version of the DSMC code which can then be extended to 3-D, pending availability of computing resources. Another important goal in the second year would be the inclusion of sulk and its more volatile oxides (SO, SO2).

  15. The long-term carbon cycle, fossil fuels and atmospheric composition.

    PubMed

    Berner, Robert A

    2003-11-20

    The long-term carbon cycle operates over millions of years and involves the exchange of carbon between rocks and the Earth's surface. There are many complex feedback pathways between carbon burial, nutrient cycling, atmospheric carbon dioxide and oxygen, and climate. New calculations of carbon fluxes during the Phanerozoic eon (the past 550 million years) illustrate how the long-term carbon cycle has affected the burial of organic matter and fossil-fuel formation, as well as the evolution of atmospheric composition.

  16. Dynamic Loading Characteristics in Metals and Composites

    DTIC Science & Technology

    2009-12-01

    and appreciated. While the static strengths of composite materials , for example, have been considerably explored and documented, fewer studies have...yield of the woven laminates varied linearly with the strain rate. As noted by Taniguchi et al. [13], most composite materials displayed strain rate...EXPERIMENTAL SETUP AND PROCEDURES The material of the specimens tested is aluminum alloy AA3003-H14. The dimensions of the specimens are given in

  17. Subarctic atmospheric aerosol composition: 1. Ambient aerosol characterization

    SciTech Connect

    Friedman, Beth; Herich, Hanna; Kammermann, Lukas; Gross, Deborah S.; Ameth, Almut; Holst, Thomas; Lohmann, U.; Cziczo, Daniel J.

    2009-07-10

    Sub-Arctic aerosol was sampled during July 2007 at the Abisko Research Station Stordalen field site operated by the Royal Swedish Academy of Sciences. Located in northern Sweden at 68º latitude and 385 meters above sea level (msl), this site is classified as a semi-continuous permafrost mire. Number density, size distribution, cloud condensation nucleus properties, and chemical composition of the ambient aerosol were determined. Backtrajectories showed that three distinct airmasses were present over Stordalen during the sampling period. Aerosol properties changed and correlated with airmass origin to the south, northeast, or west. We observe that Arctic aerosol is not compositionally unlike that found in the free troposphere at mid-latitudes. Internal mixtures of sulfates and organics, many on insoluble biomass burning and/or elemental carbon cores, dominate the number density of particles from ~200 to 2000 nm aerodynamic diameter. Mineral dust which had taken up gas phase species was observed in all airmasses. Sea salt, and the extent to which it had lost volatile components, was the aerosol type that most varied with airmass.

  18. Investigation of the small-scale structure and dynamics of Uranus' atmosphere

    NASA Technical Reports Server (NTRS)

    Eshleman, Von R.; Hinson, David P.

    1991-01-01

    This document constitutes the final technical report of the Uranus Analysis Program. Papers and/or abstracts resulting from this research are presented. The following topics are covered: (1) past and future of radio occultation studies of planetary atmospheres; (2) equatorial waves in the stratosphere of Uranus; (3) the atmosphere of Uranus- results of radio occultation measurements with Voyager 2; (4) Uranus' atmospheric dynamics and circulation; (5) small-scale structure and dynamics in the atmosphere of Uranus; (6) evidence for inertia-gravity waves in the stratosphere of Uranus derived from Voyager 2 radio occultation data; and (7) planetary waves in the equatorial stratosphere of Uranus.

  19. Introduction to the dynamics of the ocean and the atmosphere

    NASA Astrophysics Data System (ADS)

    Berroir, Andre

    1987-09-01

    The general characteristics of the atmospheric and oceanic circulation are described including stratification, geostrophy, zone distribution, Walker circulation, ocean stratification, ocean geostrophic circulation, surface circulation, Eckman pumping, and deep circulation. The energetic balance of the atmosphere-ocean system is discussed, and the Earth radiation budget is described.

  20. Dynamics of atmospheric-methane oxidation in glacier-forefield soils

    NASA Astrophysics Data System (ADS)

    Chiri, Eleonora; Nauer, Philipp A.; Rainer, Edda-Marie; Henneberger, Ruth; Zeyer, Josef; Schroth, Martin H.

    2015-04-01

    Mature upland soils are currently considered the sole terrestrial sink for atmospheric methane (CH4). But little is known about CH4 dynamics in young, developing soil ecosystems such as glacier forefields formed by progressive glacial retreat. Glacier forefields are situated on diverse bedrock types, exhibit a continuum of soil age (chronosequence), and are comprised of various geomorphological landforms, which may differ in physicochemical properties. These features may affect activity and community structure of aerobic methane-oxidizing bacteria (MOB) catalyzing atmospheric CH4 oxidation. Moreover, MOB activity and community structure may be affected by environmental parameters subject to seasonal variability such as soil temperature, water content, and nutrient availability. The aim of this study was to assess spatial and seasonal variability in atmospheric CH4 oxidation in glacier-forefield soils derived from siliceous and calcareous bedrock. Specifically, we quantified soil-atmosphere CH4 flux and CH4 oxidation activity using the soil-gas-profile method and static flux chambers in soils of different age and belonging to different landforms. In these soils MOB abundance and variation in community structure were assessed by targeting the functional gene pmoA using quantitative PCR, TRFLP-based cluster analysis, and high-throughput DNA-sequencing technology. Seasonal variability in atmospheric CH4 oxidation was assessed based on the same attributes measured with high temporal resolution throughout one snow-free season. Most glacier-forefield soils acted as a sink for atmospheric CH4 regardless of bedrock type, and CH4 flux (-0.082 to -2.2 mg CH4 m-2 d-1) and MOB abundance (2.4×103 to 5.5×105 pmoA genecopies (g soil w.w.)-1) increased significantly with soil age. Cluster analysis revealed variations in MOB community composition related to bedrock type rather than soil age, suggesting that distinct MOB communities provided a similar ecosystem service in soils on

  1. Effect of atmospheric pressure plasma treatment condition on adhesion of ramie fibers to polypropylene for composite

    NASA Astrophysics Data System (ADS)

    Li, Ying; Manolache, Sorin; Qiu, Yiping; Sarmadi, Majid

    2016-02-01

    In order to improve the interfacial adhesion between hydrophilic ramie fibers and hydrophobic polypropylene (PP) matrices, ramie fibers are modified by atmospheric pressure dielectric barrier discharge (DBD) plasma with our continuous ethanol flow technique in helium environment. A central composite design of experiments with different plasma processing parameter combinations (treatment current, treatment time and ethanol flow rate) is applied to find the most influential parameter and to obtain the best modification effect. Field emission scanning electron microscope (SEM) shows the roughened surfaces of ramie fibers from the treated groups due to plasma etching effect. Dynamic contact angle analysis (DCAA) demonstrates that the wettability of the treated fibers drastically decreases. Microbond pullout test shows that the interfacial shear strength (IFSS) between treated ramie fibers and PP matrices increases significantly. Residual gas analysis (RGA) confirms the creation of ethyl groups during plasma treatment. This study shows that our continuous ethanol flow technique is effective in the plasma modification process, during which the ethanol flow rate is the most influential parameter but all parameters have simultaneous influence on plasma modification effect of ramie fibers.

  2. The effect of protein composition on hydration dynamics.

    PubMed

    Rahaman, O; Melchionna, S; Laage, D; Sterpone, F

    2013-03-14

    Water dynamics at the surface of two homologous proteins with different thermal resistances is found to be unaffected by the different underlying amino-acid compositions, and when proteins are folded it responds similarly to temperature variations. Upon unfolding the water dynamics slowdown with respect to bulk decreases by a factor of two. Our findings are explained by the dominant topological perturbation induced by the protein on the water hydrogen bond dynamics.

  3. Exact Dynamic Stiffness Matrix for Composite Timoshenko Beams with Applications

    NASA Astrophysics Data System (ADS)

    Bannerjee, J. R.; Williams, F. W.

    1996-07-01

    In this paper, an exact dynamic stiffness matrix is presented for a composite beam. It includes the effects of shear deformation and rotatory inertia: i.e., it is for a composite Timoshenko beam. The theory accounts for the (material) coupling between the bending and torsional deformations which usually occurs for such beams due to the anisotropic nature of fibrous composites. An explicit analytical expression for each of the elements of the dynamic stiffness matrix is derived by rigorous use of the symbolic computing package REDUCE. It is proved that the use of such expressions leads to substantial savings in computer time when compared with the matrix inversion method. The use of this dynamic stiffness matrix to investigate the free vibration characteristics of composite beams (with or without the effects of shear deformation and/or rotatory inertia included) is demonstrated by applying the Wittrick-Williams algorithm. Numerical results for which comparative results are available in the literature are discussed.

  4. Dynamic Deformation Properties of Energetic Composite Materials

    DTIC Science & Technology

    2002-12-01

    the dynamic mechanical properties and detonation of energetic materials. It also included some preliminary data on the effect of particle size on the...study of the dynamic mechanical properties and detonation of energetic materials. It also included some preliminary data on the effect of particle size...qualitative only. 33 5. DEFLAGRATION-TO- DETONATION (DDT) STUDIES As part of an on-going programme to investigate the properties of ultrafine energetic

  5. Sequential composition of dynamically dexterous robot behaviors

    SciTech Connect

    Burridge, R.R.; Rizzi, A.A.; Koditschek, D.E.

    1999-06-01

    The authors report on efforts to develop a sequential robot controller-composition technique in the context of dexterous batting maneuvers. A robot with a flat paddle is required to strike repeatedly at a thrown ball until the ball is brought to rest on the paddle at a specified location. The robot`s reachable workspace is blocked by an obstacle that disconnects the free space formed when the ball and paddle remain in contact, forcing the machine to let go for a time to bring the ball to the desired state. The controller compositions the authors create guarantee that a ball introduced in the safe workspace remains there and is ultimately brought to the goal. They report on experimental results from an implementation of these formal composition methods, and present descriptive statistics characterizing the experiments.

  6. The Network for the Detection of Atmospheric Composition Change (NDACC): Satellite Validation Activities

    NASA Astrophysics Data System (ADS)

    Kurylo, Michael

    The international Network for the Detection of Atmospheric Composition Change, formerly the Network for the Detection of Stratospheric Change (NDSC) was formed to provide a consistent standardized set of long-term measurements of atmospheric trace gases, particles, and physical parameters via a suite of globally distributed research stations. Since its inception in the late 1980's and onset of official operations in 1991, the NDACC objectives have grown considerably. While the NDACC remains committed to its initial objective of monitoring changes in the stratosphere, with an emphasis on the long-term evolution of the ozone layer (its decay, likely stabilization and expected recovery), it's measurement and analysis priorities have broadened to encompass both the stratosphere and free troposphere as well as to explore the interface between changing atmospheric composition and climate. These can be summarized as • detecting trends in overall atmospheric composition and understanding their impacts on the stratosphere and troposphere, • establishing links between climate change and atmospheric composition, • calibrating and validating space-based measurements of the atmosphere, • supporting process-focused scientific field campaigns, and • testing and improving theoretical models of the atmosphere. Remote sensing measurements at the NDACC primary and complementary stations have successfully addressed each of the above objectives through participation in numerous international projects. While highlighting the network's dual goal of long-term global measurement and understanding, this talk will focus on recent satellite validation and science activities. Additional examples of NDACC measurement and analysis accomplishments as well as details about the network (its implementation, structure and operation, data archiving, and related protocols and publications) can be found at the NDACC web site - www.NDACC.org.

  7. Simulation of the impact of thunderstorm activity on atmospheric gas composition

    NASA Astrophysics Data System (ADS)

    Smyshlyaev, S. P.; Mareev, E. A.; Galin, V. Ya.

    2010-08-01

    A chemistry-climate model of the lower and middle atmosphere has been used to estimate the sensitivity of the atmospheric gas composition to the rate of thunderstorm production of nitrogen oxides at upper tropospheric and lower stratospheric altitudes. The impact that nitrogen oxides produced by lightning have on the atmospheric gas composition is treated as a subgrid-scale process and included in the model parametrically. The natural uncertainty in the global production rate of nitrogen oxides in lightning flashes was specified within limits from 2 to 20 Tg N/year. Results of the model experiments have shown that, due to the variability of thunderstorm-produced nitrogen oxides, their concentration in the upper troposphere and lower stratosphere can vary by a factor of 2 or 3, which, given the influence of nitrogen oxides on ozone and other gases, creates the potential for a strong perturbation of the atmospheric gas composition and thermal regime. Model calculations have shown the strong sensitivity of ozone and the OH hydroxyl to the amount of lightning nitrogen oxides at different atmospheric altitudes. These calculations demonstrate the importance of nitrogen oxides of thunderstorm origin for the balance of atmospheric odd ozone and gases linked to it, such as ozone and hydroxyl radicals. Our results demonstrate that one important task is to raise the accuracy of estimates of the rate of nitrogen oxide production by lightning discharges and to use physical parametrizations that take into account the local lightning effects and feedbacks arising in this case rather than climatological data in models of the gas composition and general circulation of the atmosphere.

  8. Energy balance and plume dynamics in Triton's lower atmosphere

    SciTech Connect

    Yelle, R.V.; Lunine, J.I.; Hunten, D.M. )

    1991-02-01

    The present study of the thermal balance-affecting relationships among Triton lower atmosphere thermal conduction, eddy mixing, condensation, and radiative heating indicates that, while the temperature gradient is negative in the lower atmosphere, it becomes positive at higher altitudes due to the downward conduction of ionospheric heat. This temperature profile is essentially consistent with radio-occultation experiment data; the geyser-like plumes observed by Voyager suggest that the Trioton atmosphere's convective and conductive regions join near 10-km altitude, and that the values inferred for the eddy diffusion and heat-transport coefficients indicate a profile reminiscent of the earth's. 28 refs.

  9. A comparison of the atmospheres of Jupiter and Saturn: deep atmospheric composition, cloud structure, vertical mixing, and origin.

    PubMed

    Atreya, S K; Wong, M H; Owen, T C; Mahaffy, P R; Niemann, H B; de Pater, I; Drossart, P; Encrenaz, T h

    1999-01-01

    We present our current understanding of the composition, vertical mixing, cloud structure and the origin of the atmospheres of Jupiter and Saturn. Available observations point to a much more vigorous vertical mixing in Saturn's middle-upper atmosphere than in Jupiter's. The nearly cloud-free nature of the Galileo probe entry site, a 5-micron hotspot, is consistent with the depletion of condensable volatiles to great depths, which is attributed to local meteorology. Somewhat similar depletion of water may be present in the 5-micron bright regions of Saturn also. The supersolar abundances of heavy elements, particularly C and S in Jupiter's atmosphere and C in Saturn's, as well as the progressive increase of C from Jupiter to Saturn and beyond, tend to support the icy planetesimal model of the formation of the giant planets and their atmospheres. However, much work remains to be done, especially in the area of laboratory studies, including identification of possible new microwave absorbers, and modelling, in order to resolve the controversy surrounding the large discrepancy between Jupiter's global ammonia abundance, hence the nitrogen elemental ratio, derived from the earth-based microwave observations and that inferred from the analysis of the Galileo probe-orbiter radio attenuation data for the hotspot. We look forward to the observations from Cassini-Huygens spacecraft which are expected to result not only in a rich harvest of information for Saturn, but a better understanding of the formation of the giant planets and their atmospheres when these data are combined with those that exist for Jupiter.

  10. Crossed molecular beam studies of atmospheric chemical reaction dynamics

    SciTech Connect

    Zhang, Jingsong

    1993-04-01

    The dynamics of several elementary chemical reactions that are important in atmospheric chemistry are investigated. The reactive scattering of ground state chlorine or bromine atoms with ozone molecules and ground state chlorine atoms with nitrogen dioxide molecules is studied using a crossed molecular beams apparatus with a rotatable mass spectrometer detector. The Cl + O3 → ClO + O2 reaction has been studied at four collision energies ranging from 6 kcal/mole to 32 kcal/mole. The derived product center-of-mass angular and translational energy distributions show that the reaction has a direct reaction mechanism and that there is a strong repulsion on the exit channel. The ClO product is sideways and forward scattered with respect to the Cl atom, and the translational energy release is large. The Cl atom is most likely to attack the terminal oxygen atom of the ozone molecule. The Br + O3 → ClO + O2 reaction has been studied at five collision energies ranging from 5 kcal/mole to 26 kcal/mole. The derived product center-of-mass angular and translational energy distributions are quite similar to those in the Cl + O3 reaction. The Br + O3 reaction has a direct reaction mechanism similar to that of the Cl + O3 reaction. The electronic structure of the ozone molecule seems to play the central role in determining the reaction mechanism in atomic radical reactions with the ozone molecule. The Cl + NO2 → ClO + NO reaction has been studied at three collision energies ranging from 10.6 kcal/mole to 22.4 kcal/mole. The center-of-mass angular distribution has some forward-backward symmetry, and the product translational energy release is quite large. The reaction proceeds through a short-lived complex whose lifetime is less than one rotational period. The experimental results seem to show that the Cl atom mainly attacks the oxygen atom instead of the nitrogen atom of the NO2

  11. Dynamics of elastic nonlinear rotating composite beams with embedded actuators

    NASA Astrophysics Data System (ADS)

    Ghorashi, Mehrdaad

    2009-08-01

    A comprehensive study of the nonlinear dynamics of composite beams is presented. The study consists of static and dynamic solutions with and without active elements. The static solution provides the initial conditions for the dynamic analysis. The dynamic problems considered include the analyses of clamped (hingeless) and articulated (hinged) accelerating rotating beams. Numerical solutions for the steady state and transient responses have been obtained. It is shown that the transient solution of the nonlinear formulation of accelerating rotating beam converges to the steady state solution obtained by the shooting method. The effect of perturbing the steady state solution has also been calculated and the results are shown to be compatible with those of the accelerating beam analysis. Next, the coupled flap-lag rigid body dynamics of a rotating articulated beam with hinge offset and subjected to aerodynamic forces is formulated. The solution to this rigid-body problem is then used, together with the finite difference method, in order to produce the nonlinear elasto-dynamic solution of an accelerating articulated beam. Next, the static and dynamic responses of nonlinear composite beams with embedded Anisotropic Piezo-composite Actuators (APA) are presented. The effect of activating actuators at various directions on the steady state force and moments generated in a rotating composite beam has been presented. With similar results for the transient response, this analysis can be used in controlling the response of adaptive rotating beams.

  12. Effect of Solar Radiation on the Optical Properties and Molecular Composition of Laboratory Proxies of Atmospheric Brown Carbon

    SciTech Connect

    Lee, Hyun Ji; Aiona, Paige K.; Laskin, Alexander; Laskin, Julia; Nizkorodov, Sergey

    2014-09-02

    Sources, optical properties, and chemical composition of atmospheric brown carbon (BrC) aerosol are uncertain, making it challenging to estimate its contribution to radiative forcing. Furthermore, optical properties of BrC may change significantly during its atmospheric aging. We examined the effect of solar photolysis on the molecular composition, mass absorption coefficient, and fluorescence of secondary organic aerosol prepared by high-NOx photooxidation of naphthalene (NAP SOA). The aqueous solutions of NAP SOA was observed to photobleach with an effective half-time of ~15 hours (with sun in its zenith) for the loss of the near-UV (300 -400 nm) absorbance. The molecular composition of NAP SOA was significantly modified by photolysis, with the average SOA formula changing from C14.1H14.5O5.1N0.08 to C11.8H14.9O4.5N0.02 after 4 hours of irradiation. The average O/C ratio did not change significantly, however, suggesting that it is not a good metric for assessing the extent of photolysis-driven aging in NAP SOA (and in BrC in general). In contrast to NAP SOA, the photolysis of BrC material produced by aqueous reaction of limonene+O3 SOA (LIM/O3 SOA) with ammonium sulfate was much faster, but it did not result in a significant change in the molecular level composition. The characteristic absorbance of the aged LIM/O3 SOA in the 450-600 nm range decayed with an effective half-time of <0.5 hour. This result emphasizes the highly variable and dynamic nature of different types of atmospheric BrC.

  13. Effect of solar radiation on the optical properties and molecular composition of laboratory proxies of atmospheric brown carbon.

    PubMed

    Lee, Hyun Ji Julie; Aiona, Paige Kuuipo; Laskin, Alexander; Laskin, Julia; Nizkorodov, Sergey A

    2014-09-02

    Sources, optical properties, and chemical composition of atmospheric brown carbon (BrC) aerosol are uncertain, making it challenging to estimate its contribution to radiative forcing. Furthermore, optical properties of BrC may change significantly during its atmospheric aging. We examined the effect of photolysis on the molecular composition, mass absorption coefficient, and fluorescence of secondary organic aerosol (SOA) prepared by high-NOx photooxidation of naphthalene (NAP SOA). Our experiments were designed to model photolysis processes of NAP SOA compounds dissolved in cloud or fog droplets. Aqueous solutions of NAP SOA were observed to photobleach (i.e., lose their ability to absorb visible radiation) with an effective half-life of ∼15 h (with sun in its zenith) for the loss of near-UV (300-400 nm) absorbance. The molecular composition of NAP SOA was significantly modified by photolysis, with the average SOA formula changing from C14.1H14.5O5.1N0.085 to C11.8H14.9O4.5N0.023 after 4 h of irradiation. However, the average O/C ratio did not change significantly, suggesting that it is not a good metric for assessing the extent of photolysis-driven aging in NAP SOA (and in BrC in general). In contrast to NAP SOA, the photobleaching of BrC material produced by the reaction of limonene + ozone SOA with ammonia vapor (aged LIM/O3 SOA) was much faster, but it did not result in a significant change in average molecular composition. The characteristic absorbance of the aged LIM/O3 SOA in the 450-600 nm range decayed with an effective half-life of <0.5 h. These results emphasize the highly variable and dynamic nature of different types of atmospheric BrC.

  14. Subarctic atmospheric aerosol composition: 2. Hygroscopic growth properties

    SciTech Connect

    Herich, Hanna; Kammermann, Lukas; Friedman, Beth; Gross, Deborah S.; Weingartner, E.; Lohmann, U.; Spichtinger, Peter; Gysel, Martin; Baltensperger, Urs; Cziczo, Daniel J.

    2009-07-10

    Sub-arctic aerosols were sampled during July 2007 at the Abisko Scientific Research Station Stordalen site in northern Sweden with an instrument setup consisting of a custom-built Hygroscopicity Tandem Differential Mobility Analyzer (HTDMA) connected in series to a single particle mass spectrometer. Aerosol chemical composition in the form of bipolar single particle mass spectra was determined as a function of hygroscopic growth both in situ and in real time. The HTDMA was deployed at a relative humidity of 82% and particles with a dry mobility diameter of 260 nm were selected. Aerosols from two distinct airmasses were analyzed during the sampling period. Sea salt aerosols were found to be the dominant particle group with the highest hygroscopicity. High intensities of sodium and related peaks in the mass spectra were identified as exclusive markers for large hygroscopic growth. Particles from biomass combustion were found to be the least hygroscopic aerosol category. Species normally considered soluble (e.g., sulfates and nitrates) were found in particles ranging from high to low hygroscopicity. Furthermore, the signal intensities of the peaks related to these species did not correlate with hygroscopicity.

  15. ANALYTICAL MODELS OF EXOPLANETARY ATMOSPHERES. I. ATMOSPHERIC DYNAMICS VIA THE SHALLOW WATER SYSTEM

    SciTech Connect

    Heng, Kevin; Workman, Jared E-mail: jworkman@coloradomesa.edu

    2014-08-01

    Within the context of exoplanetary atmospheres, we present a comprehensive linear analysis of forced, damped, magnetized shallow water systems, exploring the effects of dimensionality, geometry (Cartesian, pseudo-spherical, and spherical), rotation, magnetic tension, and hydrodynamic and magnetic sources of friction. Across a broad range of conditions, we find that the key governing equation for atmospheres and quantum harmonic oscillators are identical, even when forcing (stellar irradiation), sources of friction (molecular viscosity, Rayleigh drag, and magnetic drag), and magnetic tension are included. The global atmospheric structure is largely controlled by a single key parameter that involves the Rossby and Prandtl numbers. This near-universality breaks down when either molecular viscosity or magnetic drag acts non-uniformly across latitude or a poloidal magnetic field is present, suggesting that these effects will introduce qualitative changes to the familiar chevron-shaped feature witnessed in simulations of atmospheric circulation. We also find that hydrodynamic and magnetic sources of friction have dissimilar phase signatures and affect the flow in fundamentally different ways, implying that using Rayleigh drag to mimic magnetic drag is inaccurate. We exhaustively lay down the theoretical formalism (dispersion relations, governing equations, and time-dependent wave solutions) for a broad suite of models. In all situations, we derive the steady state of an atmosphere, which is relevant to interpreting infrared phase and eclipse maps of exoplanetary atmospheres. We elucidate a pinching effect that confines the atmospheric structure to be near the equator. Our suite of analytical models may be used to develop decisively physical intuition and as a reference point for three-dimensional magnetohydrodynamic simulations of atmospheric circulation.

  16. Atmospheric Dynamics of Sub-Tropical Dust Storms

    NASA Astrophysics Data System (ADS)

    Pokharel, Ashok Kumar

    Meso-alpha/beta scale observational and meso-beta/gamma scale numerical model analyses were performed to study the atmospheric dynamics responsible for generating Harmattan, Saudi Arabian, and Bodele Depression dust storms. For each dust storm case study, MERRA reanalysis datasets, WRF simulated very high resolution datasets, MODIS/Aqua and Terra images, EUMETSAT images, NAAPS aerosol modelling plots, CALIPSO images, surface observations, and rawinsonde soundings were analyzed. The analysis of each dust storm carried out separately and an in-depth comparison of the events shows some similarities among the three case studies: (1) the presence of a well-organized baroclinic synoptic scale system, (2) small scale dust emission events which occurred prior to the formation of the primary large-scale dust storms, (3) cross mountain flows which produced a strong leeside inversion layer prior to the large scale dust storm, (4) the presence of thermal wind imbalance in the exit region of the mid-tropospheric jet streak in the lee of the mountains shortly after the time of the inversion formation, (5) major dust storm formation was accompanied by large magnitude ageostrophic isallobaric low-level winds as part of the meso-beta scale adjustment process, (6) substantial low-level turbulence kinetic energy (TKE), (7) formation in the lee of nearby mountains, and (8) the emission of the dust occurred initially in narrow meso-beta scale zones parallel to the mountains, and later reached the meso-alpha scale when suspended dust was transported away from the mountains. In addition to this there were additional meso-beta scale and meso-gamma scale adjustment processes resulting in Kelvin waves in the Harmattan and the Bodele Depression cases and the thermally-forced MPS circulation in all of these three cases. The Kelvin wave preceded a cold pool accompanying the air behind the large scale cold front instrumental in the major dust storm. The Kelvin wave organized the major dust

  17. Martian Chronology and Atmospheric Composition: In Situ Measurements versus Sample Return

    NASA Technical Reports Server (NTRS)

    Bogard, Donald D.

    2008-01-01

    I examine two significant issues of martian science from the point of view of in situ measurements by robotic spacecraft versus sample return and analysis in terrestrial labs. (1) To define martian history, ages of geological processes and surface features are required. Estimated ages from surface crater densities have limitations, and the ages measured for martian meteorites cannot be associated with specific martian locales. Whereas returned martian rocks could be accurately dated, some have suggested sending a robotic spacecraft to Mars to measure rock ages using the classical K- Ar-40 technique, considered the easiest to implement. (2) To understand the evolution of the martian atmosphere and its interactions with the surface, requires precise measurements of atmospheric composition. A significant amount of information has derived from measurements by Viking and of martian meteorites. Instrumentation on the Mars Science Lander (MSL) spacecraft to be launched in the near future promises to determine atmospheric composition even more precisely. If MSL is successful, which questions about atmospheric composition will remain and thus will require atmospheric sample return to answer?

  18. Dynamic tests of composite panels of an aircraft wing

    NASA Astrophysics Data System (ADS)

    Splichal, Jan; Pistek, Antonin; Hlinka, Jiri

    2015-10-01

    The paper describes the analysis of aerospace composite structures under dynamic loading. Today, it is common to use design procedures based on assumption of static loading only, and dynamic loading is rarely assumed and applied in design and certification of aerospace structures. The paper describes the application of dynamic loading for the design of aircraft structures, and the validation of the procedure on a selected structure. The goal is to verify the possibility of reducing the weight through improved design/modelling processes using dynamic loading instead of static loading. The research activity focuses on the modelling and testing of a composite panel representing a local segment of an aircraft wing section, investigating in particular the buckling behavior under dynamic loading. Finite Elements simulation tools are discussed, as well as the advantages of using a digital optical measurement system for the evaluation of the tests. The comparison of the finite element simulations with the results of the tests is presented.

  19. Atmospheric aerosols: A literature summary of their physical characteristics and chemical composition

    NASA Technical Reports Server (NTRS)

    Harris, F. S., Jr.

    1976-01-01

    This report contains a summary of 199 recent references on the characterization of atmospheric aerosols with respect to their composition, sources, size distribution, and time changes, and with particular reference to the chemical elements measured by modern techniques, especially activation analysis.

  20. Global climate modeling of Saturn's atmosphere: exploration of seasonal variability and stratospheric dynamics

    NASA Astrophysics Data System (ADS)

    Spiga, A.; Guerlet, S.; Millour, E.; Sylvestre, M.; Fouchet, T.; Wordsworth, R.; Leconte, J.; Forget, F.; Hourdin, F.

    2013-12-01

    A leap forward on our knowledge of Saturn's stratosphere has resulted from the combination of orbital observations on board the Cassini spacecraft and state-of-the-art ground-based observations. Maps of temperature and hydrocarbons in Saturn's stratosphere revealed puzzling anomalies: equatorial oscillations with a period of about half a Saturn year, meridional circulations affecting the hydrocarbons' distribution, including possible effects of rings shadowing, "beacons" associated with the powerful 2010 Great White Spot. Those signatures, reminiscent of fundamental wave-driven phenomena in the Earth's middle atmosphere (e.g., Quasi-Biennal Oscillation, Brewer-Dobson circulation), cannot be reproduced by 1D photochemical and radiative models. This motivated us to develop a complete 3D General Circulation Model (GCM) for Saturn, based on the LMDz hydrodynamical core, to explore the circulation, seasonal variability, and wave activity in Saturn's atmosphere. In order to closely reproduce Saturn's radiative forcing, a particular emphasis was put in obtaining fast and accurate radiative transfer calculations. Our radiative model uses correlated-k distributions and spectral discretization tailored for Saturn's atmospheric composition (methane, ethane, acetylene). In addition to this, we include CIA absorption (hydrogen and helium), internal heat flux, ring shadowing, and aerosols. A systematic study is carried out on the sensitivity of the model to spectral discretization, spectroscopic databases, and aerosol scenarios (varying particle sizes, opacities and vertical structures). Temperature fields obtained with this new radiative equilibrium model are compared to that inferred from Cassini/CIRS observations. In the troposphere, our model reproduces the observed temperature knee caused by heating at the top of the tropospheric aerosol layer. In the lower stratosphere, the overall meridional gradient between the summer and the winter hemispheres agrees with observations

  1. Tailoring the electron dynamics and chemical kinetics in radio-frequency driven atmospheric pressure plasmas

    NASA Astrophysics Data System (ADS)

    Gans, Timo

    2015-09-01

    Radio-frequency atmospheric pressure plasmas are versatile and efficient sources for reactive species at ambient room temperature. The non-equilibrium chemical kinetics is initiated and determined by the electron dynamics. Due to the strongly collisional environment and associated short electron energy relaxation times the electron dynamics can be tailored using multi-frequency power coupling techniques, enabling separate control of key parameters like electron density and electron mean energy. Details of the chemical kinetics depend on the feedgas composition and desired application. Measurements and predictive simulations of key reactive species are equally challenging due to the strongly collisional environment and their multi-scale nature in space and time. The most promising approach is the exploitation of complementary advantages in direct measurements combined with specifically designed numerical simulations. The employed diagnostic techniques include picosecond laser spectroscopy, synchrotron VUV spectroscopy, IR absorption spectroscopy and nanosecond optical imaging spectroscopy. The presentation will focus on examples of He-O2-N2 mixtures for bio-medical applications and He/Ar-CO2 mixtures for CO2 conversion into value-added chemicals. This work has been supported by the UK EPSRC (EP/K018388/1 & EP/H003797/1).

  2. Improved ambiguity resolution for URTK with dynamic atmosphere constraints

    NASA Astrophysics Data System (ADS)

    Tang, Weiming; Liu, Wenjian; Zou, Xuan; Li, Zongnan; Chen, Liang; Deng, Chenlong; Shi, Chuang

    2016-12-01

    Raw observation processing method with prior knowledge of ionospheric delay could strengthen the ambiguity resolution (AR), but it does not make full use of the relatively longer wavelength of wide-lane (WL) observation. Furthermore, the accuracy of calculated atmospheric delays from the regional augmentation information has quite different in quality, while the atmospheric constraint used in the current methods is usually set to an empirical value. A proper constraint, which matches the accuracy of calculated atmospheric delays, can most effectively compensate the residual systematic biases caused by large inter-station distances. Therefore, the standard deviation of the residual atmospheric parameters should be fine-tuned. This paper presents an atmosphere-constrained AR method for undifferenced network RTK (URTK) rover, whose ambiguities are sequentially fixed according to their wavelengths. Furthermore, this research systematically analyzes the residual atmospheric error and finds that it mainly varies along the positional relationship between the rover and the chosen reference stations. More importantly, its ionospheric part of certain location will also be cyclically influenced every day. Therefore, the standard deviation of residual ionospheric error can be modeled by a daily repeated cosine or other functions with the help of data one day before, and applied by rovers as pseudo-observation. With the data collected at 29 stations from a continuously operating reference station network in Guangdong Province (GDCORS) in China, the efficiency of the proposed approach is confirmed by improving the success and error rates of AR for 10-20 % compared to that of the WL-L1-IF one, as well as making much better positioning accuracy.

  3. Dynamics and Aeroelasticity of Composite Structures.

    DTIC Science & Technology

    1987-04-22

    UNCLASSIFIED/UNLIMITEO SAME AS aPT Z OTIC USERS C3UNCLASSIFIED 22a. NAME OF RESPONSIBLE INDIVIDUAL 22b. TELEPHONE NUMBER 22c. OFFICE SYMBOL flncliads A’Wa...support related dynamic instability which could be eliminated by 3roper adjustment of the sutnport stiffness. Good agreement with linear thoery was found...Aeroelastic analysis 38 2.3 Wind Tunnel Support Stability Analysis 40 Chapter 3 Experiment 50 3.1 Wind Tunnel Model, Support System, and 50

  4. Comparison of Fully-Compressible Equation Sets for Atmospheric Dynamics

    NASA Technical Reports Server (NTRS)

    Ahmad, Nashat N.

    2016-01-01

    Traditionally, the equation for the conservation of energy used in atmospheric models is based on potential temperature and is used in place of the total energy conservation. This paper compares the application of the two equations sets for both the Euler and the Navier-Stokes solutions using several benchmark test cases. A high-resolution wave-propagation method which accurately takes into account the source term due to gravity is used for computing the non-hydrostatic atmospheric flows. It is demonstrated that there is little to no difference between the results obtained using the two different equation sets for Euler as well as Navier-Stokes solutions.

  5. Testing our Understanding of Biogenic Emissions and their Impacts on Atmospheric Composition above the Amazon Rainforest

    NASA Astrophysics Data System (ADS)

    Levine, J. G.; MacKenzie, A. R.; Squire, O. J.; Archibald, A. T.; Griffiths, P. T.; Oram, D.; Forster, G.; Lee, J. D.; Hopkins, J. R.; Bauguitte, S.; Demarco, C. F.; Artaxo, P.

    2014-12-01

    Biogenic volatile organic compounds (BVOCs) have a profound effect on atmospheric chemistry and composition, and thereby affect global air quality and climate. The Amazon rainforest constitutes an intense source of BVOCs and is thus a key location in which to probe these effects. Notable uncertainties remain regarding the amount of BVOCs emitted from the rainforest (a function of plant type, environmental conditions and physiological factors) and the quantitative influence they have on atmospheric oxidants, such as OH and O3 (a function of physical conditions and ambient atmospheric composition, not least the concentration of nitrogen oxides; NOx=NO+NO2). The effect that isoprene oxidation at low NOx concentrations has on the concentrations of OH and O3 proves a particular challenge to reproduce in atmospheric chemistry-transport models. We present here the results of a series of experiments aimed at testing our understanding of BVOC emissions from the Brazilian Amazon and the atmospheric chemistry stemming from these. We attempt to reproduce aircraft measurements of BVOCs, NOx and O3 from the South American Biomass Burning Analysis (SAMBBA) campaign in 2012, including those made close to the site of recent BVOC emission measurements, just north of Manaus, in the Cooperative LBA Atmospheric Regional Experiment (CLAIRE-UK). We compare the abilities of a variety of atmospheric chemistry mechanisms to capture the measurements in both a global atmospheric chemistry-transport model and a trajectory model of chemistry and transport. The exploration in both Eulerian and Lagrangian frameworks, with their contrasting treatments of mixing, is pertinent in view of: the sensitivity that the chemistry stemming from BVOCs shows to ambient NOx concentrations; and the episodic influence of anthropogenic emissions in this environment, for example from Manaus.

  6. Ion composition and dynamics at comet Halley

    NASA Technical Reports Server (NTRS)

    Balsiger, H.; Altwegg, K.; Buehler, F.; Geiss, J.; Ghielmetti, A. G.; Goldstein, B. E.; Goldstein, R.; Huntress, W. T.

    1986-01-01

    The Giotto space probe's ion mass spectrometer has obtained data on the composition and velocity distributions of cometary ions at distances of between 7.5 million and 1300 km from the comet Halley nucleus. Solar wind He(2+) was found throughout the coma, as close as 5000 km, with the He(+) produced by charge exchange being within about 200,000 km. A pile-up of heavy cometary ions was found at about 10,000 km from the nucleus. Inside the contact surface, which was found at about 4600 km, ion temperatures as low as about 340 K and outflow velocities of about 1 km/sec were found.

  7. Composite Higgs Dynamics on the Lattice

    NASA Astrophysics Data System (ADS)

    Pica, Claudio; Drach, Vincent; Hansen, Martin; Sannino, Francesco

    2017-03-01

    We investigate the spectrum of the SU(2) gauge theory with Nf = 2 flavors of fermions in the fundamental representation, in the continuum, using lattice simulations. This model provides a minimal template which has been used for different strongly coupled extensions of the Standard Model ranging from composite (Goldstone) Higgs models to intriguing types of dark matter candidates, such as the SIMPs. Here we will focus on the composite Goldstone Higgs paradigm, for which this model provides a minimal UV complete realization in terms of a new strong sector with fermionic matter. After introducing the relevant Lattice methods used in our simulations, we will discuss our numerical results. We show that this model features a SU(4)/Sp(4) SO(6)/SO(5) flavor symmetry breaking pattern, and estimate the value of its chiral condensate. Finally, we present our results for the mass spectrum of the lightest spin one and zero resonances, analogue to the QCD ρ, a1, σ η', a0, resonances, which are relevant for searches of new, exotic resonances at the LHC.

  8. Progressive failure of large deformation composites under dynamic tensile loading

    NASA Astrophysics Data System (ADS)

    Xing, Liqun

    The applications of polymer based composite materials in structural components under dynamic loading have increased dramatically. The accurate understanding and modeling of the material mechanical behavior is the basis for the composite structure design and analysis. This research was designed to investigate the progressive failure nature of woven polymer-based composites under dynamic tensile loading conditions. A plain-woven E-glass/vinyl ester composite was selected and a generalized anisotropic material characterization procedure was developed. Off-axial tensile dynamic loading experiments with different strain rates and temperature was conducted. A nonlinear and rate dependent constitutive model used for the polymer-based composites under tensile dynamic tensile loading was constructed. The comparison shows a good match with testing data and a good prediction of stress to failure values. A hybrid method that combined the classical laminate theory with material microstructure analysis was presented to model the large strain to failure phenomenon. A single material parameter failure criteria based on Monkman-Grant concept was built to represent the materials anisotropic and rate dependency natural for tensile loading. And the strength concept based on the material constitution relationship and failure criteria was established to for structure analyses.

  9. Dynamic evolution of coherent vortex dipole in atmospheric turbulence

    NASA Astrophysics Data System (ADS)

    Li, Jinhong; Zeng, Jun

    2017-01-01

    The analytical expression for the cross-spectral density function of Gaussian Schell-model (GSM) beams with coherent vortex dipole (CVD) propagating through atmospheric turbulence is derived, which enables us to study the evolution process of CVD propagating through atmospheric turbulence, where the influences of the beams parameters and atmospheric turbulence parameters on the ratio of critical off-axis distance to the waist width are stressed. It shows that the evolution process of the CVD depends on the off-axis distance. The larger the off-axis distance is, the more the number of CVD is. When the off-axis distance is zero, the position of coherent vortices with positive and negative topological charge of CVD propagating through atmospheric turbulence is always symmetry. When the off-axis distance is big enough, compared with the situation at source plane, the orientation of the positive coherent vortex of inherent CVD and negative coherent vortex of that rotates 180° in the far field. The larger the structure constant and the waist width are, as well as the smaller the spatial correlation length and the inner scale are, the smaller the ratio ac/w0 is. Besides, the ratio ac/w0 will no longer change when the spatial correlation length or the inner scale increases to a certain value, whereas the outer scale has no effect on the ratio.

  10. The Dynamics and Structure of Titan's Middle Atmosphere

    NASA Technical Reports Server (NTRS)

    Flasar, F. Michael

    2009-01-01

    Titan, after Venus, is the second example in the solar system of an atmosphere with a global cyclostrophic circulation. The origin and maintenance of these superrotating atmospheres is not well understood, but Titan has a strong seasonal modulation in the middle atmosphere, and the seasonal changes in the winds may offer clues. The pole in winter and early spring is characterized by temperatures 20-30 K cooler at 100-170 km than those at low latitudes, and strong circumpolar winds as high as 190 m/s at 200-250 km. At these levels the polar region is characterized by enhanced concentrations of several organic gases, and also detectable condensates. All this suggests that the polar vortex provides a mixing barrier between winter polar and lower-latitude air masses, analogous to the winter polar vortices on Earth. Because the concentrations of organic gases increase with altitude in the middle atmosphere, the observed enhancements suggest subsidence over the winter pole. Consistent with this are the observed temperatures approx.200 K at the winter-polar stratopause (280 km), making it the warmest part of the atmosphere. The warm stratopause likely results from adiabatic heating associated with the subsidence. Recent observations in late northern winter and early spring indicate that the warm anomaly at the winter-polar stratopause is weakening, and the strong zonal winds are weakening. Curiously, the stratospheric zonal winds and temperatures in both hemispheres are symmetric about a pole that is offset from the surface pole by 4 degrees. The cause of this is not well understood, but it may reflect the response of a cyclostrophic circulation to the offset between the equator, where the distance to the rotation axis is greatest, and the seasonally varying subsolar latitude.

  11. Dynamics, transport and photochemistry in the middle atmosphere of the southern hemisphere. Proceedings.

    NASA Astrophysics Data System (ADS)

    O'Neill, A.

    The workshop was the third one held as part of the Middle Atmosphere in the Southern Hemisphere (MASH) project, an international effort to learn more about dynamics, transport and photochemistry in the middle atmosphere of the southern hemisphere. Before the discovery that, during recent years, a dramatic thinning of the ozone layer takes place over Antarctica in spring - the "ozone hole" - the middle atmosphere of the southern hemisphere had received much less attention than that of the northern hemisphere from meteorologists and atmospheric chemists. The MASH project was instituted to remedy this comparative lack of interest.

  12. [Quantitative estimation source of urban atmospheric CO2 by carbon isotope composition].

    PubMed

    Liu, Wei; Wei, Nan-Nan; Wang, Guang-Hua; Yao, Jian; Zeng, You-Shi; Fan, Xue-Bo; Geng, Yan-Hong; Li, Yan

    2012-04-01

    To effectively reduce urban carbon emissions and verify the effectiveness of currently project for urban carbon emission reduction, quantitative estimation sources of urban atmospheric CO2 correctly is necessary. Since little fractionation of carbon isotope exists in the transportation from pollution sources to the receptor, the carbon isotope composition can be used for source apportionment. In the present study, a method was established to quantitatively estimate the source of urban atmospheric CO2 by the carbon isotope composition. Both diurnal and height variations of concentrations of CO2 derived from biomass, vehicle exhaust and coal burning were further determined for atmospheric CO2 in Jiading district of Shanghai. Biomass-derived CO2 accounts for the largest portion of atmospheric CO2. The concentrations of CO2 derived from the coal burning are larger in the night-time (00:00, 04:00 and 20:00) than in the daytime (08:00, 12:00 and 16:00), and increase with the increase of height. Those derived from the vehicle exhaust decrease with the height increase. The diurnal and height variations of sources reflect the emission and transport characteristics of atmospheric CO2 in Jiading district of Shanghai.

  13. Advances in geophysics. Volume 28 - issues in atmospheric and oceanic modeling. Part A - climate dynamics

    SciTech Connect

    Manabe, S.

    1985-01-01

    Papers are presented on large-scale eddies and the general circulation of the troposphere; the role of barotropic energy conversions in the general circulation; balance conditions in the earth's climate system, climate sensitivity; CO2 and hydrology; modeling of paleoclimates; and the southern oscillation and El Nino. Topics treated include the stratospheric dynamics of the middle atmosphere, wave-mean-flow interaction in the middle atmosphere, radiative-dynamical interactions in the middle atmosphere, and a mechanistic interpretation of stratospheric tracer transport. Consideration is given to the general circulation of Venus, and Jovian and comparative atmospheric modeling. Also discussed are the modeling of ocean circulation, tropical oceanography, the simulation of mesoscale ocean variability in midlatitude gyres, modeling circulation and mixing in estuaries and coastal oceans, and the modeling of sea-ice dynamics.

  14. SIMULATION OF SUMMER-TIME DIURNAL BACTERIAL DYNAMICS IN THE ATMOSPHERIC SURFACE LAYER

    EPA Science Inventory

    A model was prepared to simulate the observed concentration dynamics of culturable bacteria in the diurnal summer atmosphere at a Willamette River Valley, Oregon location. The meteorological and bacterial mechanisms included in a dynamic null-dimensional model with one-second tim...

  15. Extracting Compositional Variation from THEMIS Data for Features with Large Topography on Mars Via Atmospheric Equalization

    NASA Technical Reports Server (NTRS)

    Anderson, F. S.; Drake, J. S.; Hamilton, V. E.

    2005-01-01

    We have developed a means of equalizing the atmospheric signature in Mars Odyssey Thermal Emission Imaging System (THEMIS) infrared data over regions with large topography such as the Valles Marineris (VM). This equalization allows for the analysis of compositional variations in regions that previously have been difficult to study because of the large differences in atmospheric path length that result from large changes in surface elevation. Specifically, our motivation for this study is to examine deposits that are small at the scales observable by the Thermal Emission Spectrometer (TES) onboard Mars Global Surveyor, but which are more readily resolved with THEMIS.

  16. Dynamic initiation and propagation of cracks in unidirectional composite plates

    NASA Astrophysics Data System (ADS)

    Coker, Demirkan

    Dynamic crack growth along weak planes is a significant mode of failure in composites and other layered/sandwiched structures and is also the principal mechanism of shallow crustal earthquakes. In order to shed light on this phenomenon dynamic crack initiation and propagation characteristics of a model fiber-reinforced unidirectional graphite/epoxy composite plate was investigated experimentally. Dynamic fracture experiments were conducted by subjecting the composite plates to in-plane, symmetric and asymmetric, impact loading. The lateral shearing interferometric technique of coherent gradient sensing (CGS) in conjunction with high-speed photography was used to visualize the failure process in real time. It was found that mode-I cracks propagated subsonically with crack speeds increasing to the neighborhood of the Rayleigh wave speed of the composite. Also in mode-I, the dependence of the dynamic initiation fracture toughness on the loading rate was determined and was found to be constant for low loading rates and to increase rapidly above K˙dI>10 5 . The dynamic crack propagation toughness, KID, was observed to decrease with crack tip speed up to the Rayleigh wave speed of the composite. For asymmetric, mode-II, types of loading the results revealed highly unstable and intersonic shear-dominated crack growth along the fibers. These cracks propagated with unprecedented speeds reaching 7400 m/s which is the dilatational wave speed of the composite along the fibers. For intersonic crack growth, the interferograms, featured a shock wave structure typical of disturbances traveling with speeds higher than one of the characteristic wave speeds in the solid. In addition high speed thermographic measurements are conducted that show concentrated hot spots behind the crack tip indicating non-uniform crack face frictional contact. In addition, shear dominated dynamic crack growth is investigated along composite/Homalite interfaces subjected to impact loading. The crack

  17. Plasma dynamics and energetics in the solar atmosphere

    NASA Technical Reports Server (NTRS)

    Vanhoven, Gerard

    1992-01-01

    Prominence condensation and support, the dynamics of coronal loops, and streamer structure and disconnection are briefly discussed. Prominence condensation and magnetic levitation in a coronal loop and simulations of coronal disconnection events are discussed.

  18. Exploration of the link between Emiliania huxleyi bloom dynamics and aerosol fluxes to the lower Atmosphere

    NASA Astrophysics Data System (ADS)

    Trainic, M.

    2013-12-01

    shells are emitted as aerosols, but also that aerosol type and therefore chemical composition, microphysical and optical properties depend on the stage of the bloom growth. Unraveling the atmospheric signature of algal bloom dynamics in the ocean will provide novel insights into its ecological and climatic roles.

  19. Atmospheric Dynamics on Uranus in the millimeter and sub-millimeter

    NASA Astrophysics Data System (ADS)

    Schonwald, Anna; Hofstadter, Mark; Butler, Bryan J.; Gurwell, Mark A.; Moullet, Arielle

    2016-10-01

    Characterizing the atmospheric dynamics of Uranus is important to understand its structure, evolution, and energetics. In addition, most of the exoplanets discovered to date are roughly the same size and mass as our solar system's ice giants, therefore a fuller understanding of Uranus will aid in the study of exoplanets. Most observations of Uranus's atmospheric dynamics are derived from infrared observations, but these observations probe to a depth of only a few bars. In contrast, radio wavelength observations can probe up to tens of bars. Early cm-wavelength observations in the 1980's and 1990's from the Very Large Array (VLA) showed enhanced brightness temperatures at the South Pole [1], inferred to be due to a deep Hadley cell circulation [2]. Observations with the Submillimeter Array (SMA) hinted at similar structure, but the signal-to-noise ratio was limiting [3]. The vertical extent of this Hadley cell is an important parameter and can help our understanding of the the circulation itself and the chemical species involved in that circulation; mm-wavelength observations similar to those from the VLA would help determine this. Using the Atacama Large Millimeter Array (ALMA), a sensitive array for mm and submm-wavelength observations, the vertical extent of this circulation can be constrained. We utilized publicly available calibration data at wavelengths of 0.8 and 1.3 mm from October 2011 to December 2012 and combined them to make the most sensitive images of Uranus to date at these wavelengths. Due to the sensitivity of these wavelengths at the 1-5 bar depth on Uranus, and the ability to express variations of brightness temperature latitudinally, we see clear brightness temperature enhancements at the North Pole at both wavelengths and hints of similar enhancements at far southern latitudes. This indicates that the circulation penetrates at least as high as 1 bar. We will discuss the observed features' implications for the composition and temperature

  20. Ionospheric manifestations of earthquakes and tsunamis in a dynamic atmosphere

    NASA Astrophysics Data System (ADS)

    Godin, Oleg A.; Zabotin, Nikolay A.; Zabotina, Liudmila

    2015-04-01

    Observations of the ionosphere provide a new, promising modality for characterizing large-scale physical processes that occur on land and in the ocean. There is a large and rapidly growing body of evidence that a number of natural hazards, including large earthquakes, strong tsunamis, and powerful tornadoes, have pronounced ionospheric manifestations, which are reliably detected by ground-based and satellite-borne instruments. As the focus shifts from detecting the ionospheric features associated with the natural hazards to characterizing the hazards for the purposes of improving early warning systems and contributing to disaster recovery, it becomes imperative to relate quantitatively characteristics of the observed ionospheric disturbances and the underlying natural hazard. The relation between perturbations at the ground level and their ionospheric manifestations is strongly affected by parameters of the intervening atmosphere. In this paper, we employ the ray theory to model propagation of acoustic-gravity waves in three-dimensionally inhomogeneous atmosphere. Huygens' wavefront-tracing and Hamiltonian ray-tracing algorithms are used to simulate propagation of body waves from an earthquake hypocenter through the earth's crust and ocean to the upper atmosphere. We quantify the influence of temperature stratification and winds, including their seasonal variability, and air viscosity and thermal conductivity on the geometry and amplitude of ionospheric disturbances that are generated by seismic surface waves and tsunamis. Modeling results are verified by comparing observations of the velocity fluctuations at altitudes of 150-160 km by a coastal Dynasonde HF radar system with theoretical predictions of ionospheric manifestations of background infragravity waves in the ocean. Dynasonde radar systems are shown to be a promising means for monitoring acoustic-gravity wave activity and observing ionospheric perturbations due to earthquakes and tsunamis. We will discuss

  1. CANOES II; Dynamics of Atmospheric Infrared Thermochemical Excitation. Volume 2

    DTIC Science & Technology

    1989-03-01

    4 8 which carried at least 6.5 eV internal energy, in their studies on the excitation of mercuric halides by N2 (A). The energy of the companion...as auroral precursors of infrared radiation ., 20. DISTRIBUTION /AVAILABILITY OF ABSTRACT 21 ABSTRACT SECURITY CLASSIFICATION MUNCLASSIFIED/tINLIMITED...investigate chemiluminescent reactions of atmospherically important radiators which could significantly contribute to emissions in several important

  2. Impact ejecta dynamics in an atmosphere - Experimental results and extrapolations

    NASA Technical Reports Server (NTRS)

    Schultz, P. H.; Gault, D. E.

    1982-01-01

    It is noted that the impacts of 0.635-cm aluminum projectiles at 6 km/sec into fine pumice dust, at 1 atm, generate a ball of ionized gas behind an expanding curtain of upward moving ejecta. The gas ball forms a toroid which dissolves as it is driven along the interior of the ejecta curtain, by contrast to near-surface explosions in which a fireball envelops early-time crater growth. High frame rate Schlieren photographs show that the atmosphere at the base of the ejecta curtain is initially turbulent, but later forms a vortex. These experiments suggest that although small size ejecta may be decelerated by air drag, they are not simply lofted and suspended but become incorporated in an ejecta cloud that is controlled by air flow which is produced by the response of the atmosphere to the impact. The extrapolation of these results to large body impacts on the earth suggests such contrasts with laboratory experiments as a large quantity of impact-generated vapor, the supersonic advance of the ejecta curtain, the lessened effect of air drag due to the tenuous upper atmosphere, and the role of secondary cratering.

  3. Ablation Resistance of C/C Composites with Atmospheric Plasma-Sprayed W Coating

    NASA Astrophysics Data System (ADS)

    Zhou, Zhe; Wang, Yuan; Gong, Jieming; Ge, Yicheng; Peng, Ke; Ran, Liping; Yi, Maozhong

    2016-12-01

    To improve the ablation resistance of carbon/carbon (C/C) composites, tungsten (W) coating with thickness of 1.2 mm was applied by atmospheric plasma spraying. The antiablation property of the coated composites was evaluated by oxyacetylene flame ablation experiments. The phase composition of the coating was investigated by a combination of x-ray diffraction analysis and scanning electron microscopy with energy-dispersive x-ray spectroscopy analysis. The ablation resistance of the coated C/C substrates was compared with that of uncoated C/C composites and C/C-CuZr composites after ablation for 30 s. The properties of the coated C/C composites after ablation time of 10, 30, 60, 90, 120, and 180 s were further studied. The results indicated that the mass and linear ablation rates of the W-coated C/C composites were lower than those of uncoated C/C or C/C-CuZr composites after ablation for 30 s. The coating exhibited heat stability after 120 s of ablation, with mass loss and linear ablation rates of 7.39 × 10-3 g/s and 3.50 × 10-3 mm/s, respectively. However, the W coating became ineffective and failed after ablation for 180 s. Three ablation regions could be identified, in which the ablation mechanism of the coating changed from thermochemical to thermophysical erosion to mechanical scouring with increasing ablation time.

  4. Dynamic gold nanoparticle, polymer-based composites

    NASA Astrophysics Data System (ADS)

    Firestone, Millicent; Junghans, Ann; Hayden, Steven; Majeski, Jaroslaw; CINT, Lujan Team

    2014-03-01

    Artificial polymer-based biomembranes may serve as a foundational architecture for the integration and spatial organization of metal nanoparticles forming functional nanocomposites. Nonionic triblock copolymer (PEO-PPO-PEO), lipid-based gels, containing Au nanoparticles (NPs) can be prepared by either external doping of the preformed nanoparticles or by in-situ reduction of Au 3+. Neutron reflectivity on quartz supported thin films of the Au NP -doped polymer-based biomembranes was used to determine the location of the Au. The nanoparticles were found to preferentially reside within the ethylene oxide chains located at the interface of the bulk water channels and the amphiphile bilayers. The embedded Au nanoparticles can act as localized heat sinks, inducing changes in the polymer conformation. The collective, thermally-triggered expansion and contraction of the EO chains modulate the mesophase structure of the gels. Synchrotron X-ray scattering (SAXS) was used to monitor mesophase structure as a function of both temperature and photo-irradiation. These studies represent a first step towards designingexternally-responsive polymer-nanoparticle composites.

  5. The microbiome of the upper troposphere: species composition and prevalence, effects of tropical storms, and atmospheric implications

    NASA Astrophysics Data System (ADS)

    Nenes, A.; DeLeon-Rodriguez, N.; Lathem, T. L.; Rodriguez-Rojas, L. M.; Barazesh, J.; Anderson, B. E.; Beyersdorf, A.; Ziemba, L. D.; Bergin, M. H.; Konstantinidis, K.

    2012-12-01

    The composition and prevalence of microorganisms in the middle to upper troposphere (8-15 km altitude) and their role in aerosol-cloud-precipitation interactions represent important, unresolved questions for biological and atmospheric science. Here we report on the microbiome of low and high altitude air masses sampled onboard the NASA DC-8 platform during the 2010 Genesis and Rapid Intensification Processes (GRIP) campaign in the Caribbean Sea. The samples were collected in cloudy and cloud-free air masses, before, during, and after two major tropical hurricanes, Earl and Karl. Quantitative PCR and microscopy revealed that viable bacterial cells represented on average around 20% of the total particles in the 0.25-1μm diameter range and were at least an order of magnitude more abundant compared to fungal cells, suggesting that bacteria represent an important and underestimated fraction of micron-sized atmospheric aerosols. The samples from the two hurricanes were characterized by significantly different bacterial communities, revealing that hurricanes aerosolize a large amount of new cells. Nonetheless, 17 bacterial taxa, including taxa that are known to utilize C1-C4 carbon compounds present in the atmosphere, were found in all samples, indicating that these organisms have developed adaptations to survive in the troposphere. The findings presented here suggest that the microbiome is a dynamic and underappreciated aspect of the upper troposphere with potentially profound impacts on the water cycle, clouds, and climate.

  6. Chemical Composition and Dynamics of the Upper Troposphere and the Lower Stratosphere: Overview of the Project

    NASA Astrophysics Data System (ADS)

    Sofieva, V. F.; Liu, C.; Huang, F.; Kyrola, E.; Liu, Y.; Ialongo, I.; Hakkarainen, J.; Zhang, Y.

    2016-08-01

    The DRAGON-3 cooperation study on the upper troposphere and the lower stratosphere (UTLS) is based on new satellite data and modern atmospheric models. The objectives of the project are: (i) assessment of satellite data on chemical composition in UTLS, (ii) dynamical and chemical structures of the UTLS and its variability, (iii) multi-scale variability of stratospheric ozone, (iv) climatology of the stratospheric aerosol layer and its variability, and (v) updated ozone climatology and its relation to tropopause/multiple tropopauses.In this paper, we present the main results of the project.

  7. Trends in Mesospheric Dynamics and Chemistry: Simulations With a Model of the Entire Atmosphere

    NASA Astrophysics Data System (ADS)

    Brasseur, G. P.

    2005-05-01

    The cooling resulting from infrared CO2 radiative transfer is a major contribution to the energy budget of the middle atmosphere and thermosphere. The rapid increase of the atmospheric CO2 concentration resulting from anthropogenic emissions is therefore expected to lead, in general, to a substantial cooling in this height range. This can potentially be counteracted by heating due to absorption of near infrared radiation by CO2. Changes in ozone as a consequence of increasing methane and water vapor may also have an impact on the energy budget as dynamical changes caused by increased tropospheric temperatures. By means of numerical simulations with a general circulation and chemistry model of the entire atmosphere we will address the following questions: 1.) Can state-of-the-art atmospheric modeling explain the mesospheric temperature trends observed during the last decades? 2.)Which part of the temperature changes resulting from an increase of atmospheric CO2 is caused by local changes in the radiative budget and which part is influenced by remote dynamical effects? The model used is the newly developed Hamburg Model of the Neutral and Ionized Atmosphere (HAMMONIA) that resolves the atmosphere from the Earth's surface up to about 250 km altitude, and is based on the 3-D dynamics from the ECHAM5 general circulation model and the chemistry scheme from MOZART-3. Results from different time slice experiment representative of years 1970 and 2000, and for a doubling of CO2 will be presented.

  8. Venus: chemical weathering of igneous rocks and buffering of atmospheric composition.

    PubMed

    Nozette, S; Lewis, J S

    1982-04-09

    Data from the Pioneer Venus radar mapper, combined with measurements of wind velocity and atmospheric composition, suggest that surface erosion on Venus varies with altitude. Calcium- and magnesium-rich weathering products are produced at high altitudes by gas-solid reactions with igneous minerals, then removed into the hotter lowlands by surface winds. These fine-grained weathering products may then rereact with the lower atmosphere and buffer the composition of the observed gases carbon dioxide, water vapor, sulfur dioxide, and hydrogen fluoride in some regions of the surface. This process is a plausible mechanism for the establishment in the lowlands of a calcium-rich mineral assemblage, which had previously been found necessary for the buffering of these species.

  9. Venus - Chemical weathering of igneous rocks and buffering of atmospheric composition

    NASA Technical Reports Server (NTRS)

    Nozette, S.; Lewis, J. S.

    1982-01-01

    Data from the Pioneer Venus radar mapper, combined with measurements of wind velocity and atmospheric composition, suggest that surface erosion on Venus varies with altitude. Calcium- and magnesium-rich weathering products are produced at high altitudes by gas-solid reactions with igneous minerals, then removed into the hotter lowlands by surface winds. These fine-grained weathering products may then rereact with the lower atmosphere and buffer the composition of the observed gases carbon dioxide, water vapor, sulfur dioxide, and hydrogen fluoride in some regions of the surface. This process is a plausible mechanism for the establishment in the lowlands of a calcium-rich mineral assemblage, which had previously been found necessary for the buffering of these species.

  10. Effect of rising atmospheric carbon dioxide concentration on the protein composition of cereal grain.

    PubMed

    Wroblewitz, Stefanie; Hüther, Liane; Manderscheid, Remy; Weigel, Hans-Joachim; Wätzig, Hermann; Dänicke, Sven

    2014-07-16

    The present study investigates effects of rising atmospheric CO2 concentration on protein composition of maize, wheat, and barley grain, especially on the fractions prolamins and glutelins. Cereals were grown at different atmospheric CO2 concentrations to simulate future climate conditions. Influences of two nitrogen fertilization levels were studied for wheat and barley. Enriched CO2 caused an increase of globulin and B-hordein of barley. In maize, the content of globulin, α-zein, and LMW polymers decreased, whereas total glutelin, zein, δ-zein, and HMW polymers rose. Different N supplies resulted in variations of barley subfractions and wheat globulin. Other environmental influences showed effects on the content of nearly all fractions and subfractions. Variations in starch-protein bodies caused by different CO2 treatments could be visualized by scanning electron microscopy. In conclusion, climate change would have impacts on structural composition of proteins and, consequently, on the nutritional value of cereals.

  11. The Structure and Dynamics of Titan's Middle Atmosphere and Troposphere

    NASA Technical Reports Server (NTRS)

    Flasar, F.M.; Achterberg, R.K.; Schinder, P.J.

    2009-01-01

    Titan, after Venus, is the second example in the solar system of an atmosphere with a global cyclostrophic circulation. The origin and maintenance of these superrotating atmospheres is not well understood, but Titan has a strong seasonal modulation in the middle atmosphere, and the seasonal changes in the winds may offer clues. The pole in winter and early spring is characterized by temperatures 20-30 K cooler at 140-170 km than those at low latitudes, and strong circumpolar winds as high as 190 m/s at 200- 250 km. At these levels the polar region is characterized by enhanced concentrations of several organic gases, and also detectable condensates. All this suggests that the polar vortex provides a mixing barrier between winter polar and lower-latitude air masses, analogous to the polar ozone holes on Earth. Because the concentrations of organic gases increase with altitude in the middle atmosphere, the observed enhancements suggest subsidence over the winter pole. Consistent with this are the observed temperatures approximately 200 K at the winter-polar stratopause (280 km), making it the warmest part of the atmosphere. The warm stratopause likely results from adiabatic heating associated with the subsidence. Recent observations in late northern winter and early spring indicate that the warm anomaly at the winter-polar stratopause is weakening;. In contrast to the middle atmosphere, latitude contrasts in tropospheric temperatures are muted. During the northern winter season, they were approximately 5 K at the tropopause and 3 K or less near the surface, being coldest at high northern latitudes. This is understandable in terms of the long radiative relaxation times in the troposphere, compared to times that are much shorter than a season in the upper stratosphere and higher. Curiously, the transition between the small meridional contrast (and presumably seasonal variations) in temperatures observed in the troposphere and the large variations observed at higher

  12. Mission Objectives Of The Atmospheric Composition Related Sentinels S5p, S4, And S5

    NASA Astrophysics Data System (ADS)

    Ingmann, Paul; Veihelmann, Ben; Langen, Jorg; Meijer, Yasjka

    2013-12-01

    Atmospheric chemistry observations from space have been made for over 30 years, in the beginning mainly by US missions. These missions have always been motivated by the concern about a number of environmental issues. At present European instruments like GOME-2 on MetOp/EPS-A and -B and OMI on NASA's Aura are in space and, despite being designed for research purposes, perform routine observations. The space instruments have helped improving our understanding of processes that govern stratospheric ozone depletion, climate change and the transport of pollutants. However, long-term continuous time series of atmospheric trace gas data have been limited to stratospheric ozone and a few related species. According to current planning, meteorological satellites will maintain these observations over the next decade. They will also add some measurements of tropospheric trace gases critical for climate forcing. However, as their measurements have been motivated by meteorology, vertical sensitivities and accuracies are marginal for atmospheric chemistry applications. With the exception of stratospheric ozone, reliable long-term space-based monitoring of atmospheric constituents with quality attributes sufficient to serve atmospheric chemistry applications still need to be established. The need for a GMES atmospheric service (GAS), its scope and high level requirements were laid down in an orientation papers organised by the European Commission and then updated by an Implementation Group (IG) [1], backed by four working groups, advising the Commission on scope, architecture, in situ and space requirements. The goal of GAS is to provide coherent information on atmospheric variables in support of European policies and for the benefit of European citizens. Services cover air quality, climate change/forcing, stratospheric ozone and solar radiation. To meet the needs of the user community atmospheric composition mission concepts for GEO and LEO have been defined usually referred to

  13. Dynamic Data-Driven Event Reconstruction for Atmospheric Releases

    SciTech Connect

    Mirin, A; Serban, R; Kosovic, B

    2005-03-14

    This is a collaborative LDRD Exploratory Research project involving four directorates--Energy & Environment, Engineering, NAI and Computation. The project seeks to answer the following critical questions regarding atmospheric releases--''How much material was released? When? Where? and What are the potential consequences?'' Inaccurate estimation of the source term can lead to gross errors, time delays during a crisis, and even fatalities. We are developing a capability that seamlessly integrates observational data streams with predictive models in order to provide the best possible estimates of unknown source term parameters, as well as optimal and timely situation analyses consistent with both models and data. Our approach utilizes Bayesian inference and stochastic sampling methods (Markov Chain and Sequential Monte Carlo) to reformulate the inverse problem into a solution based on efficient sampling of an ensemble of predictive simulations, guided by statistical comparisons with data. We are developing a flexible and adaptable data-driven event-reconstruction capability for atmospheric releases that provides (1) quantitative probabilistic estimates of the principal source-term parameters (e.g., the time-varying release rate and location); (2) predictions of increasing fidelity as an event progresses and additional data become available; and (3) analysis tools for sensor network design and uncertainty studies. Our computational framework incorporates multiple stochastic algorithms, operates with a range and variety of atmospheric models, and runs on multiple computer platforms, from workstations to large-scale computing resources. Our final goal is a multi-resolution capability for both real-time operational response and high fidelity multi-scale applications.

  14. The Influence of CO2 Admixtures on the Product Composition in a Nitrogen-Methane Atmospheric Glow Discharge Used as a Prebiotic Atmosphere Mimic.

    PubMed

    Mazankova, V; Torokova, L; Krcma, F; Mason, N J; Matejcik, S

    2016-11-01

    This work extends our previous experimental studies of the chemistry of Titan's atmosphere by atmospheric glow discharge. The Titan's atmosphere seems to be similarly to early Earth atmospheric composition. The exploration of Titan atmosphere was initiated by the exciting results of the Cassini-Huygens mission and obtained results increased the interest about prebiotic atmospheres. Present work is devoted to the role of CO2 in the prebiotic atmosphere chemistry. Most of the laboratory studies of such atmosphere were focused on the chemistry of N2 + CH4 mixtures. The present work is devoted to the study of the oxygenated volatile species in prebiotic atmosphere, specifically CO2 reactivity. CO2 was introduced to the standard N2 + CH4 mixture at different mixing ratio up to 5 % CH4 and 3 % CO2. The reaction products were characterized by FTIR spectroscopy. This work shows that CO2 modifies the composition of the gas phase with the detection of oxygenated compounds: CO and others oxides. There is a strong influence of CO2 on increasing concentration other products as cyanide (HCN) and ammonia (NH3).

  15. The Influence of CO2 Admixtures on the Product Composition in a Nitrogen-Methane Atmospheric Glow Discharge Used as a Prebiotic Atmosphere Mimic

    NASA Astrophysics Data System (ADS)

    Mazankova, V.; Torokova, L.; Krcma, F.; Mason, N. J.; Matejcik, S.

    2016-11-01

    This work extends our previous experimental studies of the chemistry of Titan's atmosphere by atmospheric glow discharge. The Titan's atmosphere seems to be similarly to early Earth atmospheric composition. The exploration of Titan atmosphere was initiated by the exciting results of the Cassini-Huygens mission and obtained results increased the interest about prebiotic atmospheres. Present work is devoted to the role of CO2 in the prebiotic atmosphere chemistry. Most of the laboratory studies of such atmosphere were focused on the chemistry of N2 + CH4 mixtures. The present work is devoted to the study of the oxygenated volatile species in prebiotic atmosphere, specifically CO2 reactivity. CO2 was introduced to the standard N2 + CH4 mixture at different mixing ratio up to 5 % CH4 and 3 % CO2. The reaction products were characterized by FTIR spectroscopy. This work shows that CO2 modifies the composition of the gas phase with the detection of oxygenated compounds: CO and others oxides. There is a strong influence of CO2 on increasing concentration other products as cyanide (HCN) and ammonia (NH3).

  16. Production, Isotopic Composition, and Atmospheric Fate of Biologically Produced Nitrous Oxide

    NASA Astrophysics Data System (ADS)

    Stein, Lisa Y.

    The anthropogenic production of greenhouse gases and their consequent effects on global climate have garnered international attention for years. A remaining challenge facing scientists is to unambiguously quantify both sources and sinks of targeted gases. Microbiological metabolism accounts for the largest source of nitrous oxide (N2O), mostly due to global conversion of land for agriculture and massive usage of nitrogen-based fertilizers. A most powerful method for characterizing the sources of N2O lies in its multi-isotope signature. This review summarizes mechanisms that lead to biological N2O production and how discriminate placement of 15N into molecules of N2O occurs. Through direct measurements and atmospheric modeling, we can now place a constraint on the isotopic composition of biological sources of N2O and trace its fate in the atmosphere. This powerful interdisciplinary combination of biology and atmospheric chemistry is rapidly advancing the closure of the global N2O budget.

  17. Influence of atmospheric processes on the solubility and composition of iron in Saharan dust

    SciTech Connect

    Longo, Amelia F.; Feng, Yan; Lai, Barry; Landing, William M.; Shelley, Rachel U.; Nenes, Athanasios; Mihalopoulos, Nikolaos; Violaki, Kalliopi; Ingall, Ellery D.

    2016-06-10

    Aerosol iron was examined in Saharan dust plumes using a combination of iron near-edge X-ray absorption spectroscopy and wet-chemical techniques. Aerosol samples were collected at three sites located in the Mediterranean, the Atlantic, and Bermuda to characterize iron at different atmospheric transport lengths and time scales. Iron(III) oxides were a component of aerosols at all sampling sites and dominated the aerosol iron in Mediterranean samples. In Atlantic samples, iron(II and III) sulfate, iron(III) phosphate, and iron(II) silicates were also contributors to aerosol composition. With increased atmospheric transport time, iron(II) sulfates are found to become more abundant, aerosol iron oxidation state became more reduced, and aerosol acidity increased. As a result, atmospheric processing including acidic reactions and photoreduction likely influence the form of iron minerals and oxidation state in Saharan dust aerosols and contribute to increases in aerosol-iron solubility.

  18. Influence of atmospheric processes on the solubility and composition of iron in Saharan dust

    DOE PAGES

    Longo, Amelia F.; Feng, Yan; Lai, Barry; ...

    2016-06-10

    Aerosol iron was examined in Saharan dust plumes using a combination of iron near-edge X-ray absorption spectroscopy and wet-chemical techniques. Aerosol samples were collected at three sites located in the Mediterranean, the Atlantic, and Bermuda to characterize iron at different atmospheric transport lengths and time scales. Iron(III) oxides were a component of aerosols at all sampling sites and dominated the aerosol iron in Mediterranean samples. In Atlantic samples, iron(II and III) sulfate, iron(III) phosphate, and iron(II) silicates were also contributors to aerosol composition. With increased atmospheric transport time, iron(II) sulfates are found to become more abundant, aerosol iron oxidation statemore » became more reduced, and aerosol acidity increased. As a result, atmospheric processing including acidic reactions and photoreduction likely influence the form of iron minerals and oxidation state in Saharan dust aerosols and contribute to increases in aerosol-iron solubility.« less

  19. On the role of internal atmospheric variability in ENSO dynamics

    NASA Astrophysics Data System (ADS)

    Zhang, Li

    In the first part of this dissertation we use an Intermediate Coupled Model to develop a quantitative test to validate the null hypothesis that low-frequency variation of ENSO predictability may be caused by stochastic processes. Three "perfect model scenario" prediction experiments are carried out, where the model is forced either solely by stochastic forcing or additionally by decadal-varying backgrounds with different amplitudes. These experiments indicate that one can not simply reject the null hypothesis unless the decadal-varying backgrounds are unrealistically strong. The second part of this dissertation investigates the extent to which internal atmospheric variability (IAV) can influence ENSO variation, and examines the underlying physical mechanisms linking IAV to ENSO variability with the aid of a newly developed coupled model consisting of an atmospheric general circulation model and a Zebiak-Cane type of reduced gravity ocean model. A novel noise filter algorithm is developed to suppress IAV in the coupled model. A long control coupled simulation, where the filter is not employed, demonstrates that the coupled model captures many statistical properties of the observed ENSO behavior. It further shows that the development of El Nino is linked to a boreal spring phenomenon referred to as the Pacific Meridional Model (MM). The MM, characterized by an anomalous north-south SST gradient and anomalous surface circulation in the northeasterly trade regime with maximum variance in boreal spring, is inherent to thermodynamic ocean-atmosphere coupling in the Intertropical Convergence Zone latitude. The Northern Pacific Oscillation provides one source of external forcing to excite it. This result supports the hypothesis that the MM works as a conduit for extratropical atmospheric influence on ENSO. A set of coupled simulations, where the filter is used to suppress IAV, indicate that reducing IAV in both wind stress and heat flux substantially weakens ENSO variance

  20. Phase stability and dynamics of entangled polymer-nanoparticle composites

    SciTech Connect

    Mangal, Rahul; Srivastava, Samanvaya; Archer, Lynden A.

    2015-06-10

    Nanoparticle–polymer composites, or polymer–nanoparticle composites (PNCs), exhibit unusual mechanical and dynamical features when the particle size approaches the random coil dimensions of the host polymer. Here, we harness favourable enthalpic interactions between particle-tethered and free, host polymer chains to create model PNCs, in which spherical nanoparticles are uniformly dispersed in high molecular weight entangled polymers. Investigation of the mechanical properties of these model PNCs reveals that the nanoparticles have profound effects on the host polymer motions on all timescales. On short timescales, nanoparticles slow-down local dynamics of the host polymer segments and lower the glass transition temperature. On intermediate timescales, where polymer chain motion is typically constrained by entanglements with surrounding molecules, nanoparticles provide additional constraints, which lead to an early onset of entangled polymer dynamics. Finally, on long timescales, nanoparticles produce an apparent speeding up of relaxation of their polymer host.

  1. Phase stability and dynamics of entangled polymer–nanoparticle composites

    PubMed Central

    Mangal, Rahul; Srivastava, Samanvaya; Archer, Lynden A.

    2015-01-01

    Nanoparticle–polymer composites, or polymer–nanoparticle composites (PNCs), exhibit unusual mechanical and dynamical features when the particle size approaches the random coil dimensions of the host polymer. Here, we harness favourable enthalpic interactions between particle-tethered and free, host polymer chains to create model PNCs, in which spherical nanoparticles are uniformly dispersed in high molecular weight entangled polymers. Investigation of the mechanical properties of these model PNCs reveals that the nanoparticles have profound effects on the host polymer motions on all timescales. On short timescales, nanoparticles slow-down local dynamics of the host polymer segments and lower the glass transition temperature. On intermediate timescales, where polymer chain motion is typically constrained by entanglements with surrounding molecules, nanoparticles provide additional constraints, which lead to an early onset of entangled polymer dynamics. Finally, on long timescales, nanoparticles produce an apparent speeding up of relaxation of their polymer host. PMID:26044723

  2. Molecular composition of atmospheric aerosols from Halley Bay, Antarctica, using ultra-high resolution mass spectrometry

    NASA Astrophysics Data System (ADS)

    Kourtchev, Ivan; Brough, Neil; Rincon, Angela; Jones, Anna; Kalberer, Markus

    2016-04-01

    Antarctica is one of the few pristine places to study natural processes of atmospheric aerosols and anthropogenic impacts on the clean remote atmosphere. Although stratospheric aerosol in Antarctica has now been explored in some detail because of the ozone depletion phenomenon, tropospheric aerosol particles in Antarctica remain very little studied. The main goal of this work is to identify in detail the organic chemical composition of aerosol from Halley Bay station, which is located on the Brunt Ice Shelf floating on the Weddell Sea in Antarctica. In this study we characterise the molecular composition of aerosols from three seasons (summer, autumn and winter in 2012) using ultra-high resolution mass spectrometry (UHRMS). The technique provides high accuracy and high mass resolving power that allows determining unambiguous number of organic compounds present in complex organic mixtures (Noziere et al., 2015). The molecular composition interpretation was facilitated using visualisation methods (e.g. double bond equivalent, Van Krevelen diagrams, Kendrick mass analysis, and carbon oxidation state), which allowed to identify patterns, such as differences between sampling times and atmospheric processes. The majority of the identified compounds were attributed to nitrogen and sulphur containing species which exhibited very strong seasonal trends. Relatively large fraction (up to 30% of the total number of molecules) of these species contained very low hydrogen to carbon ratios (below 1) indicating that the site is impacted by anthropogenic emissions. Influences of the meteorological parameters and air mass trajectories on the molecular composition are discussed. Nozière et al., The Molecular Identification of Organic Compounds in the Atmosphere: State of the Art and Challenges, Chem. Rev., 115, 3920-3983, 2015.

  3. An Exact Solvable Model of Rocket Dynamics in Atmosphere

    ERIC Educational Resources Information Center

    Rodrigues, H.; Pinho, M. O.; Portes, D., Jr.; Santiago, A.

    2009-01-01

    In basic physics courses at undergraduate level, the dynamics of self-propelled bodies is presented as an example of momentum conservation law applied to systems with time-varying mass. However, is often studied the simple situation of free motion or the motion under the action of a constant gravitational field. In this work, we investigate the…

  4. The Structure and Dynamics of Titan's Middle Atmosphere

    NASA Technical Reports Server (NTRS)

    Flasar, F. M.; Achterberg, R. K.

    2008-01-01

    Titan's middle atmosphere is characterized by cyclostrophic winds and strong seasonal modulation. Cassini CIRS observations, obtained in northern winter, indicate that the stratosphere near l mbar is warmest at low latitudes, with the South Pole a few degrees colder and the North Pole approximately 20 K colder. Associated with the cold northern temperatures are strong circumpolar winds with speeds as high as 190 m/s. Within this vortex, the mixing ratios of several organic gases are enhanced relative to those at low latitudes. Comparison with Voyager thermal infrared measurements, obtained 25 years ago in northern spring, suggests that the enhancement currently observed will increase as the winter progresses. The stratopause height, increases from 0.1 mbar near the equator to 0.01 mbar near the North Pole, where it is the warmest part of the atmosphere, greater than 200 K. This implies subsidence at the pole, which is consistent with the enhanced organics observed. Condensate features, several still not identified, are also apparent in the infrared spectra at high northern latitudes. In many ways, the winter vortex observed on Titan, with cyclostrophic winds, resembles the polar winter vortices on the Earth, where the mean winds are geostrophic.

  5. The Atmospheric Dynamics of Jupiter, Saturn, and Titan

    NASA Technical Reports Server (NTRS)

    Flasar, F. M.

    2009-01-01

    Comparative studies of Jupiter and Saturn often emphasize their similarities, but recent observations have highlighted important differences. The stratospheres of both planets exhibit an equatorial oscillation reminiscent of that in Earth's middle atmosphere. Jupiter's oscillation has a 4-5 year period, not linked to its season, and it has been modeled as an analog to the terrestrial quasi-biennial oscillation, driven by the stresses associated with vertically propagating waves. Saturn's equatorial oscillation is nearly semiannual, but wave activity may still be a driver. Jupiter's internal rotation rate is inferred from its steady modulated radio emission. Saturn's internal rotation is more enigmatic. It has been inferred from the modulation of the body's kilometric radio emission, but this period has varied by 1% over the last 25 years. Saturn's equatorial winds are also puzzling, as those inferred from cloud tracking by Cassini and more recent HST observations are weaker than those from Voyager. Whether this is attributable to a difference in altitudes of the tracked clouds in winds with vertical shear or a real temporal change in the winds is not known. Both winter and summer poles of Saturn exhibit very compact circumpolar vortices with warm cores, indicating subsidence. Titan's middle atmosphere is characterized by global cyclostrophic winds, particularly the strong circumpolar vortex in the winter hemisphere. In many ways, the spatial distribution of temperature, gaseous constituents, and condensates is reminiscent of conditions in terrestrial winter vortices, albeit with different chemistry. The meridional contrast in Titan's tropospheric temperatures is small, only a few kelvins.

  6. The structure and dynamics of Titan's middle atmosphere.

    PubMed

    Flasar, F M; Achterberg, R K

    2009-02-28

    Titan's middle atmosphere is characterized by cyclostrophic winds and strong seasonal modulation. Cassini CIRS observations, obtained in northern winter, indicate that the stratosphere near 1mbar is warmest at low latitudes, with the South Pole a few degrees colder and the North Pole approximately 20K colder. Associated with the cold northern temperatures are strong circumpolar winds with speeds as high as 190ms-1. Within this vortex, the mixing ratios of several organic gases are enhanced relative to those at low latitudes. Comparison with Voyager thermal infrared measurements, obtained 25 years ago in northern spring, suggests that the enhancement currently observed will increase as the winter progresses. The stratopause height increases from 0.1mbar near the equator to 0.01mbar near the North Pole, where it is the warmest part of the atmosphere, greater than 200K. This implies subsidence at the pole, which is consistent with the enhanced organics observed. Condensate features, several still not identified, are also apparent in the infrared spectra at high northern latitudes. In many ways, the winter vortex observed on Titan, with cyclostrophic winds, resembles the polar winter vortices on the Earth, where the mean winds are geostrophic.

  7. Tracing changes in atmospheric sources of lead contamination using lead isotopic compositions in Australian red wine.

    PubMed

    Kristensen, Louise Jane; Taylor, Mark Patrick; Evans, Andrew James

    2016-07-01

    Air quality data detailing changes to atmospheric composition from Australia's leaded petrol consumption is spatially and temporally limited. In order to address this data gap, wine was investigated as a potential proxy for atmospheric lead conditions. Wine spanning sixty years was collected from two wine regions proximal to the South Australian capital city, Adelaide, and analysed for lead concentration and lead and strontium isotopic composition for source apportionment. Maximum wine lead concentrations (328 μg/L) occur prior to the lead-in-air monitoring in South Australia in the later 1970s. Wine lead concentrations mirror available lead-in-air measurements and show a declining trend reflecting parallel reductions in leaded petrol emissions. Lead from petrol dominated the lead in wine ((206)Pb/(207)Pb: 1.086; (208)Pb/(207)Pb: 2.360) until the introduction of unleaded petrol, which resulted in a shift in the wine lead isotopic composition closer to vineyard soil ((206)Pb/(207)Pb: 1.137; (208)Pb/(207)Pb: 2.421). Current mining activities or vinification processes appear to have no impact with recent wine samples containing less than 4 μg/L of lead. This study demonstrates wine can be used to chronicle changes in environmental lead emissions and is an effective proxy for atmospherically sourced depositions of lead in the absence of air quality data.

  8. Dynamics of the solar atmosphere. VI. Resonant oscillations of an atmospheric cavity: observations.

    NASA Astrophysics Data System (ADS)

    Deubner, F.-L.; Waldschik, T.; Steffens, S.

    1996-03-01

    We have evaluated new, spatially one- and two-dimensional time series of photospheric and chromospheric Fraunhofer lines at a large number of positions in the line profile, with the 'lambdameter' method. As a result we have obtained the velocity and brightness fluctuations corresponding to many closely staggered height levels in the atmosphere, and their respective phase spectra as a diagnostic of the wave fields involved. This material has not only served to define more accurately and specifically the character of the 180deg phase jump observed before in V-I spectra of the NaD_2_ line in internetwork regions, and to reveal the narrow height interval that gives rise to this discontinuity in the phase spectra. We have also discovered another discontinuity in V-V spectra of the same Fraunhofer line at nearly the same frequency (7.0mHz). Since neither running nor standing waves alone can explain the observed solitary phase discontinuities, our results provide strong evidence in favour of an atmosphere that supports (at least, and probably more than) one eigenmode as a component of the wave field.

  9. Structure and dynamics of decadal anomalies in the wintertime midlatitude North Pacific ocean-atmosphere system

    NASA Astrophysics Data System (ADS)

    Fang, Jiabei; Yang, Xiu-Qun

    2016-09-01

    The structure and dynamics of decadal anomalies in the wintertime midlatitude North Pacific ocean-atmosphere system are examined in this study, using the NCEP/NCAR atmospheric reanalysis, HadISST SST and Simple Ocean Data Assimilation data for 1960-2010. The midlatitude decadal anomalies associated with the Pacific Decadal Oscillation are identified, being characterized by an equivalent barotropic atmospheric low (high) pressure over a cold (warm) oceanic surface. Such a unique configuration of decadal anomalies can be maintained by an unstable ocean-atmosphere interaction mechanism in the midlatitudes, which is hypothesized as follows. Associated with a warm PDO phase, an initial midlatitude surface westerly anomaly accompanied with intensified Aleutian low tends to force a negative SST anomaly by increasing upward surface heat fluxes and driving southward Ekman current anomaly. The SST cooling tends to increase the meridional SST gradient, thus enhancing the subtropical oceanic front. As an adjustment of the atmospheric boundary layer to the enhanced oceanic front, the low-level atmospheric meridional temperature gradient and thus the low-level atmospheric baroclinicity tend to be strengthened, inducing more active transient eddy activities that increase transient eddy vorticity forcing. The vorticity forcing that dominates the total atmospheric forcing tends to produce an equivalent barotropic atmospheric low pressure north of the initial westerly anomaly, intensifying the initial anomalies of the midlatitude surface westerly and Aleutian low. Therefore, it is suggested that the midlatitude ocean-atmosphere interaction can provide a positive feedback mechanism for the development of initial anomaly, in which the oceanic front and the atmospheric transient eddy are the indispensable ingredients. Such a positive ocean-atmosphere feedback mechanism is fundamentally responsible for the observed decadal anomalies in the midlatitude North Pacific ocean-atmosphere

  10. The spectral element dynamical core in the Community Atmosphere Model

    NASA Astrophysics Data System (ADS)

    Taylor, Mark

    2013-11-01

    I will describe our work developing CAM-SE, a highly scalable version of the Community Atmosphere Model (CAM). CAM-SE solves the hydrostatic equations with a spectral element horizontal descritization and the hybrid coordinate Simmons & Burridge (1981) vertical discretization. It uses a mimetic formulation of spectral elements which preserves the adjoint and annihilator properties of the divergence, gradient and curl operations. These mimetic properties result in local conservation (to machine precision) of mass, tracer mass and (2D) potential vorticity, and semi-discrete conservation (exact with exact time-discretization) of total energy. Hyper-viscsoity is used for all numerical dissipation. The spectral element method naturally supports unstructured/variable resolution grids. We are using this capability to perform simulations with 1/8 degree resolution over the central U.S., transitioning to 1 degree over most of the globe. This is a numerically efficient way to study the resolution sensitivity of CAM's many subgrid parameterizations.

  11. Effective dynamic moduli and density of fiber-reinforced composites

    NASA Astrophysics Data System (ADS)

    Caleap, Mihai; Drinkwater, Bruce W.; Wilcox, Paul D.

    2013-01-01

    A multiple scattering theory is developed to predict the effective dynamic material properties of elastic composites in two dimensions. The system consists of circular fibers distributed randomly in an elastic solid. The coherent wave propagation in the elastic composite is analyzed under the quasi-crystalline approximation. The effective medium equivalent to the original composite material is a medium with space and time dispersion, and hence, its parameters are functions of frequency of the incident field. Although the effective medium is homogeneous and isotropic, its effective dynamic moduli and density depend on the type of propagating wave, e.g., they are different for longitudinal and transverse incident waves. However, they coincide in the long-wave region as expected on physical grounds. Furthermore, the effective material properties are found to be complexvalued, in addition to their dynamic nature. For in-plane waves and in the long-wave limit the effective bulk modulus, mass density and shear modulus are independently determined by a set of monopolar, dipolar and quadrupolar scattering coefficients of the embedded fibers alone, respectively. Likewise, for anti-plane waves, the effective mass density and the shear modulus are specified, respectively, in terms of the monopolar and dipolar scattering coefficients of the corresponding fiberscattering problem. The emerging possibility of designing composite materials to form elastic metamaterials is discussed.

  12. Fundamental composite electroweak dynamics: Status at the LHC

    NASA Astrophysics Data System (ADS)

    Arbey, Alexandre; Cacciapaglia, Giacomo; Cai, Haiying; Deandrea, Aldo; Le Corre, Solène; Sannino, Francesco

    2017-01-01

    Using the recent joint results from the ATLAS and CMS collaborations on the Higgs boson, we determine the current status of composite electroweak dynamics models based on the expected scalar sector. Our analysis can be used as a minimal template for a wider class of models between the two limiting cases of composite Goldstone Higgs and Technicolor-like ones. This is possible due to the existence of a unified description, both at the effective and fundamental Lagrangian levels, of models of composite Higgs dynamics where the Higgs boson itself can emerge, depending on the way the electroweak symmetry is embedded, either as a pseudo-Goldstone boson or as a massive excitation of the condensate. In our template, a mass term for the fermions in the fundamental theory acts as a stabilizer of the Higgs potential, without the need for partners of the top quark. We constrain the available parameter space at the effective Lagrangian level. We show that a wide class of models of fundamental composite electroweak dynamics are still compatible with the present constraints. The results are relevant for the ongoing and future searches at the Large Hadron Collider.

  13. Intraoperative Analysis of Flow Dynamics in Arteriovenous Composite Y Grafts

    PubMed Central

    Lobo Filho, Heraldo Guedis; Lobo Filho, José Glauco; Pimentel, Matheus Duarte; Silva, Bruno Gadelha Bezerra; de Souza, Camylla Santos; Montenegro, Marília Leitão; Leitão, Maria Cláudia de Azevedo; Jamacuru, Francisco Vagnaldo Fechine

    2016-01-01

    Objective Composite graft of left internal thoracic artery and great saphenous vein in revascularization of the left coronary system is a technique well described in literature. The aim of this study is to analyze blood flow dynamics in this configuration of composite graft especially in what concerns left internal thoracic artery's adaptability and influence of great saphenous vein segment on left internal thoracic artery's flow. Methods Revascularization of left coronary system with composite graft, with left internal thoracic artery revascularizing the anterior interventricular artery and a great saphenous vein segment, anastomosed to the left internal thoracic artery, revascularizing another branch of the left coronary system, was performed in 23 patients. Blood flow was evaluated by transit time flowmetry in all segments of the composite graft (left internal thoracic artery proximal segment, left internal thoracic artery distal segment and great saphenous vein segment). Measures were performed in baseline condition and after dobutamine-induced stress, without and with non-traumatic temporary clamping of the distal segments of the composite graft. Results Pharmacological stress resulted in increase of blood flow values in the analyzed segments (P<0.05). Non-traumatic temporary clamping of great saphenous vein segment did not result in statistically significant changes in the flow of left internal thoracic artery distal segment, both in baseline condition and under pharmacological stress. Similarly, non-traumatic temporary clamping of left internal thoracic artery distal segment did not result in statistically significant changes in great saphenous vein segment flow. Conclusion Composite grafts with left internal thoracic artery and great saphenous vein for revascularization of left coronary system, resulted in blood flow dynamics with physiological adaptability, both at rest and after pharmacological stress, according to demand. Presence of great saphenous vein

  14. Unraveling the Dynamics of Aminopolymer/Silica Composites

    SciTech Connect

    Carrillo, Jan-Michael Y.; Sakwa-Novak, Miles A.; Holewinski, Adam; Potter, Matthew E.; Rother, Gernot; Jones, Christopher W.; Sumpter, Bobby G.

    2016-02-25

    Branched poly(ethylenimine) (PEI) encapsulated within mesoporous silica (SBA-15), has proven to be an eective sorbent for developing carbon capture technologies. However, the structure-property correlations which govern their adsorptive properties is not well understood. By combining coarse-grained molecular dynamics simulations and neutron scattering experiments we are able to construct, and validate, a detailed model of the dynamics and morphology of the conned polymer within the mesoporous support. By varying the simulation properties we are able to probe, for the rst time, the direct relationship between the structure of the polymer and the non-monotonic dynamics of the polymer as a function of monomer concentration within an adsorbing cylindrical pore. Overall the simulation results are in good agreement with quasi-elastic neutron scattering (QENS) studies, suggesting an approach that can be a useful guide for understanding how to tune porous polymer composites for enhancing desired dynamical and structural behavior targeting enhanced carbon dioxide adsorption.

  15. The atmospheric structure and dynamical properties of Neptune derived from ground-based and IUE spectrophotometry

    NASA Technical Reports Server (NTRS)

    Baines, Kevin H.; Smith, Wm. Hayden

    1990-01-01

    A wide range of recent full-disk spectral observations is used to constrain the atmospheric structure and dynamical properties of Neptune; analytical determinations are made of the abundances of such spectrally active gas species as the deep-atmosphere CH4 molar fraction and the mean ortho/para hydrogen ratio in the visible atmosphere, as well as stratospheric and tropospheric aerosol properties. Compared to Uranus, the greater abundance and shorter lifetimes of Neptunian particulates in the stratospheric region irradiated by the solar UV flux indicate that such radiation is the darkening agent of stratospheric aerosols on both planets.

  16. The atmospheric structure and dynamical properties of Neptune derived from ground-based and IUE spectrophotometry

    NASA Astrophysics Data System (ADS)

    Baines, K. H.; Smith, H. Wm.

    1990-05-01

    A wide range of recent full-disk spectral observations is used to constrain the atmospheric structure and dynamical properties of Neptune; analytical determinations are made of the abundances of such spectrally active gas species as the deep-atmosphere CH4 molar fraction and the mean ortho/para hydrogen ratio in the visible atmosphere, as well as stratospheric and tropospheric aerosol properties. Compared to Uranus, the greater abundance and shorter lifetimes of Neptunian particulates in the stratospheric region irradiated by the solar UV flux indicate that such radiation is the darkening agent of stratospheric aerosols on both planets.

  17. Lunar atmosphere. How surface composition and meteoroid impacts mediate sodium and potassium in the lunar exosphere.

    PubMed

    Colaprete, A; Sarantos, M; Wooden, D H; Stubbs, T J; Cook, A M; Shirley, M

    2016-01-15

    Despite being trace constituents of the lunar exosphere, sodium and potassium are the most readily observed species due to their bright line emission. Measurements of these species by the Ultraviolet and Visible Spectrometer (UVS) on the Lunar Atmosphere and Dust Environment Explorer (LADEE) have revealed unambiguous temporal and spatial variations indicative of a strong role for meteoroid bombardment and surface composition in determining the composition and local time dependence of the Moon's exosphere. Observations show distinct lunar day (monthly) cycles for both species as well as an annual cycle for sodium. The first continuous measurements for potassium show a more repeatable variation across lunations and an enhancement over KREEP (Potassium Rare Earth Elements and Phosphorus) surface regions, revealing a strong dependence on surface composition.

  18. Constraints on Earth degassing history from the argon isotope composition of Devonian atmosphere

    NASA Astrophysics Data System (ADS)

    Stuart, F. M.; Mark, D.

    2012-04-01

    The primordial and radiogenic isotopes of the noble gases combine to make them a powerful tool for determining the time and tempo of the outgassing of the Earth's interior. The outgassing history of the Earth is largely constrained from measurements of the isotopic composition of He, Ne, Ar and Xe in samples of modern mantle, crust and atmosphere. There have been few unequivocal measurement of the isotopic composition of noble gases in ancient atmosphere. We have re-visited whether ancient Ar is trapped in the ~400 Ma Rhynie chert [1]. We have analysed samples of pristine Rhynie chert using the ARGUS multi-collector mass spectrometer calibrated against the new determination of atmospheric Ar isotope ratios [2]. 40Ar/36Ar ratios are low, with many lower than the modern air value (298.8). Importantly these are accompanied by atmospheric 38Ar/36Ar ratios indicating that the low 40Ar/36Ar are not due to mass fractionation. We conclude that the Rhynie chert has captured Devonian atmosphere-derived Ar. The data indicate that the Devonian atmosphere 40Ar/36Ar was at least 3 % lower than the modern air value. Thus the Earth's atmosphere has accumulated at least 5 ± 0.2 x 1016 moles of 40Ar in the last 400 million years, at an average rate of 1.24 ± 0.06 x 108 mol 40Ar/year. This overlaps the rate determined from ice cores for the last 800,000 years [3] and implies that there has been no resolvable temporal change in Earth outgassing rate since mid-Palaeozoic times. The new data require the Earth outgassed early, and suggests that pristine samples of Archaean and Proterozoic chert may prove useful as palaeo-atmosphere tracers. [1] G. Turner, J. Geol. Soc. London 146, 147-154 (1989) [2] D. Mark, F.M. Stuart, M. de Podesta, Geochim. Cosmochim. Acta 75, 7494-7501 [3] M. Bender et al., Proc. Nat. Acad. Sci. 105, 8232-8237 (2008)

  19. Atmospheric dynamics in Laboratory Biosphere with wheat and sweet potato crops

    NASA Astrophysics Data System (ADS)

    Dempster, W. F.; Allen, J. P.; Alling, A.; Nelson, M.; Silvertone, S.; van Thillo, M.

    Laboratory Biosphere is a 40 m3 closed life system equipped with 12000 watts of high pressure sodium lamps over planting beds with 5.37 m2 of soil. Atmospheric composition changes due to photosynthetic fixation of carbon dioxide and corresponding production of oxygen or the reverse, respiration, are observed in short timeframes, eg. hourly. To focus on inherent characteristics of the crop as distinct from its area or the volume of the chamber, we report fixation and respiration rates in millimoles per hour per square meter of planted area. An 85 day crop of USU Apogee wheat under a 16 hour lighted / 8 hour dark regime peaked in fixation rate at about 100 mmol h-1 m-2 approximately 24 days after planting. Light intensity was about 840 mol m-2 s-1. Dark respiration peaked at about 31 mmol h-1 m-2 at the same time. Thereafter, both fixation and respiration declined toward zero as harvest time approached. A residual soil respiration rate of about 1.9 mmol h-1 m-2 was observed in the dark closed chamber for 100 days after the harvest. A 126 day crop of Tuskegee TU-82-155 sweet potato behaved quite differently. Under a 680 mol m-2 s-1, 18 hour lighted / 6 hour dark regime, fixation during lighted hours rose to a plateau ranging from about 27 to 48 mmol h-1 m-2 after 42 days and respiration settled into a range of 12 to 23 mmol h-1 m-2. These rates continued unabated until the harvest at 126 days, suggesting that tuber biomass production might have continued at about the same rate for some time beyond the harvest time that was exercised in this experiment. In both experiments CO2 levels were allowed to range widely from a few hundred ppm to about 3000 ppm, which permitted observation of fixation rates both at varying CO2 concentrations and at each number of days after planting. This enables plotting the fixation rate as a function of both variables. Understanding the atmospheric dynamics of individual crops will be essential for design and atmospheric management of more

  20. Atmospheric dynamics in the “Laboratory Biosphere” with wheat and sweet potato crops

    NASA Astrophysics Data System (ADS)

    Dempster, William F.; Allen, J. P.; Alling, A.; Silverstone, S.; Van Thillo, M.

    Laboratory Biosphere is a 40-m 3 closed life system equipped with 12,000 W of high pressure sodium lamps over planting beds with 5.37 m 2 of soil. Atmospheric composition changes due to photosynthetic fixation of carbon dioxide and corresponding production of oxygen or the reverse, respiration, are observed in short timeframes, e.g., hourly. To focus on inherent characteristics of the crop as distinct from its area or the volume of the chamber, we report fixation and respiration rates in mmol h -1 m -2 of planted area. An 85-day crop of USU Apogee wheat under a 16-h lighted/8-h dark regime peaked in fixation rate at about 100 mmol h -1 m -2 approximately 24 days after planting. Light intensity was about 840 μmol m -2 s -1. Dark respiration peaked at about 31 mmol h -1 m -2 at the same time. Thereafter, both fixation and respiration declined toward zero as harvest time approached. A residual soil respiration rate of about 1.9 mmol h -1 m -2 was observed in the dark closed chamber for 100 days after the harvest. A 126-day crop of Tuskegee TU-82-155 sweet potato behaved quite differently. Under a 680 μmol m -2 s -1, 18-h lighted/6-h dark regime, fixation during lighted hours rose to a plateau ranging from about 27 to 48 mmol h -1 m -2 after 42 days and dark respiration settled into a range of 12-23 mmol h -1 m -2. These rates continued unabated until the harvest at 126 days, suggesting that tuber biomass production might have continued at about the same rate for some time beyond the harvest time that was exercised in this experiment. In both experiments CO 2 levels were allowed to range widely from a few hundred to about 3000 ppm, which permitted observation of fixation rates both at varying CO 2 concentrations and at each number of days after planting. This enables plotting the fixation rate as a function of both variables. Understanding the atmospheric dynamics of individual crops will be essential for design and atmospheric management of more complex CELSS which

  1. Atmospheric pCO2 control on speleothem stable carbon isotope compositions

    NASA Astrophysics Data System (ADS)

    Breecker, Daniel O.

    2017-01-01

    The stable carbon isotope compositions of C3 plants are controlled by the carbon isotope composition of atmospheric CO2 (δ13Ca) and by the stomatal response to water stress. These relationships permit the reconstruction of ancient environments and assessment of the water use efficiency of forests. It is currently debated whether the δ13C values of C3 plants are also controlled by atmospheric pCO2. Here I show that globally-averaged speleothem δ13C values closely track atmospheric pCO2 over the past 90 kyr. After accounting for other possible effects, this coupling is best explained by a C3 plant δ13C sensitivity of - 1.6 ± 0.3 ‰ / 100 ppmV CO2 during the Quaternary. This is consistent with 20th century European forest tree ring δ13C records, providing confidence in the result and suggesting that the modest pCO2-driven increase in water use efficiency determined for those ecosystems and simulated by land surface models accurately approximates the global average response. The δ13C signal from C3 plants is transferred to speleothems relatively rapidly. Thus, the effect of atmospheric pCO2 should be subtracted from new and existing speleothem δ13C records so that residual δ13C shifts can be interpreted in light of the other factors known to control spleleothem δ13C values. Furthermore, global average speleothem δ13C shifts may be used to develop a continuous radiometric chronology for Pleistocene atmospheric pCO2 fluctuations and, by correlation, ice core climate records.

  2. Capillary and micropacked columns for in situ analysis of Titan's atmospheric composition

    NASA Astrophysics Data System (ADS)

    Sternberg, R.; Szopa, C.; Coscia, D.; Raulin, F.; Vidal-Madjar, C.; Niemann, H.

    Since the beginning of the space exploration, most of the many probes which have been sent to explore other planetary atmospheres and surfaces carried instruments to determine their elemental, isotopic and molecular -inorganic as well as organic- compositions. As Mass Spectrometry (MS) and Gas Chromatography (GC) are powerful analytical techniques which fulfil the severe constraints of space instrumentation (mass, size, mechanical strength, automation and energy consumption), they have been the techniques the most frequently used for in situ chemical analysis of extraterrestrial environments, essentially Mars and Venus in the 70s and 80s. After 20 years and the investigation of Venus atmosphere by the Vega probe, they will be used again next year to investigate the atmosphere of a fascinating world : Titan Because of its composition (rich in organics) and density (similar to the Earth's one), the study of the atmosphere of Titan is of primary interest for understanding a reducing chemistry at the scale of a planet, which could have played a role in the prebiotic chemistry of the primitive Earth. The Gas Chromatograph Mass Spectrometer (GCMS) experiment is one of the main instruments of the Huygens probe of the Cassini-Huygens mission to Saturn, and it will aim at analysing the atmospheric composition. This original gas chromatography based experiment will use for the first time capillary chromatographic columns in space. Indeed the GC subsystem includes three columns which operate in parallel, each one targeting a specific series of compounds : i) a carbon molecular sieve micropacked column used for the separation of CO, N2 and other permanent gases ; ii) a capillary column to separate the light hydrocarbons containing up to 3 carbon atoms ; iii) a second capillary column with cyanopropyl dimethyl polysiloxane stationary phase to analyze the heavier hydrocarbons, aromatics, and the low molecular weight nitriles, containing up to 4 carbon atoms. These heavier

  3. Constraining the atmospheric composition of the day-night terminators of HD 189733b: Atmospheric retrieval with aerosols

    SciTech Connect

    Lee, Jae-Min; Irwin, Patrick G. J.; Fletcher, Leigh N.; Barstow, Joanna K.; Heng, Kevin

    2014-07-01

    A number of observations have shown that Rayleigh scattering by aerosols dominates the transmission spectrum of HD 189733b at wavelengths shortward of 1 μm. In this study, we retrieve a range of aerosol distributions consistent with transmission spectroscopy between 0.3-24 μm that were recently re-analyzed by Pont et al. To constrain the particle size and the optical depth of the aerosol layer, we investigate the degeneracies between aerosol composition, temperature, planetary radius, and molecular abundances that prevent unique solutions for transit spectroscopy. Assuming that the aerosol is composed of MgSiO{sub 3}, we suggest that a vertically uniform aerosol layer over all pressures with a monodisperse particle size smaller than about 0.1 μm and an optical depth in the range 0.002-0.02 at 1 μm provides statistically meaningful solutions for the day/night terminator regions of HD 189733b. Generally, we find that a uniform aerosol layer provide adequate fits to the data if the optical depth is less than 0.1 and the particle size is smaller than 0.1 μm, irrespective of the atmospheric temperature, planetary radius, aerosol composition, and gaseous molecules. Strong constraints on the aerosol properties are provided by spectra at wavelengths shortward of 1 μm as well as longward of 8 μm, if the aerosol material has absorption features in this region. We show that these are the optimal wavelengths for quantifying the effects of aerosols, which may guide the design of future space observations. The present investigation indicates that the current data offer sufficient information to constrain some of the aerosol properties of HD189733b, but the chemistry in the terminator regions remains uncertain.

  4. Fluid Dynamics of Urban Atmospheres in Complex Terrain

    NASA Astrophysics Data System (ADS)

    Fernando, H. J. S.

    2010-01-01

    A majority of the world's urban centers are located in complex terrain, in which local airflow patterns are driven by pressure gradients and thermal forcing, while being strongly influenced by topographic effects and human (anthropogenic) activities. A paradigm in this context is a city located in a valley surrounded by mountains, slopes, and escarpments, in which the airflow is determined by terrain-induced perturbations to synoptic (background) flow, mesoscale thermal circulation (valley/slope flows) generated by local heating or cooling, and by their interaction with factitious (e.g., buildings and roads) and natural (e.g., vegetation and terrain) elements. The dynamics of airflows intrinsic to urban areas in complex terrain is reviewed here by employing idealized flow configurations to illustrate fundamental processes. Urban flows span a wide range of space and time scales and the emphasis here is on mesoscales (1-100 km). Basic fluid dynamics plays a central role in explaining observations of urban flow and in developing subgrid parameterizations for predictive models.

  5. Dynamics of apokamp-type atmospheric pressure plasma jets

    NASA Astrophysics Data System (ADS)

    Sosnin, Eduard A.; Panarin, Victor A.; Skakun, Victor S.; Baksht, Evgeny Kh.; Tarasenko, Victor F.

    2017-02-01

    The paper describes a new discharge source of atmospheric pressure plasma jets (APPJs) in air with no gas supply through the discharge region. In this discharge mode, plasma jets develop from the bending point of a bright current channel between two electrodes and are therefore termed an apokamp (from Greek `off' and `bend'). The apokamp can represent single plasma jets of length up 6 cm or several jets, and the temperature of such jets can range from more than 1000 °C at their base to 100-250 °C at their tip. Apokamps are formed at maximum applied voltage of positive polarity, provided that the second electrode is capacitively decoupled with ground. According to high-speed photography with time resolution from several nanoseconds to several tens of nanoseconds, the apokamp consists of a set of plasma bullets moving with a velocity of 100-220 km/s, which excludes the convective mechanism of plasma decay. Estimates on a 100-ns scale show that the near-electrode zones and the zones from which apokamps develop are close in temperature.

  6. Mass conservative, positive definite integrator for atmospheric chemical dynamics

    NASA Astrophysics Data System (ADS)

    Nguyen, Khoi; Caboussat, Alexandre; Dabdub, Donald

    2009-12-01

    Air quality models compute the transformation of species in the atmosphere undergoing chemical and physical changes. The numerical algorithms used to predict these transformations should obey mass conservation and positive definiteness properties. Among all physical phenomena, the chemical kinetics solver provides the greatest challenge to attain these two properties. In general, most chemical kinetics solvers are mass conservative but not positive definite. In this article, a new numerical algorithm for the computation of chemical kinetics is presented. The integrator is called Split Single Reaction Integrator (SSRI). It is both mass conservative and positive definite. It solves each chemical reaction exactly and uses operator splitting techniques (symmetric split) to combine them into the entire system. The method can be used within a host integrator to fix the negative concentrations while preserving the mass, or it can be used as a standalone integrator that guarantees positive definiteness and mass conservation. Numerical results show that the new integrator, used as a standalone integrator, is second order accurate and stable under large fixed time steps when other conventional integrators are unstable.

  7. Three-dimensional dynamical and chemical modelling of the upper atmosphere

    NASA Technical Reports Server (NTRS)

    Prinn, R. G.; Alyea, F. N.; Cunnold, D. M.

    1976-01-01

    Progress in coding a 3-D upper atmospheric model and in modeling the ozone perturbation resulting from the shuttle booster exhaust is reported. A time-dependent version of a 2-D model was studied and the sulfur cycle in the stratosphere was investigated. The role of meteorology in influencing stratospheric composition measurements was also studied.

  8. The Atmospheric Dynamics Mission on the International Space Station--A new technique for observing winds in the atmosphere

    SciTech Connect

    Ingmann, P.; Readings, C. J.; Knott, K.

    1999-01-22

    For the post-2000 time-frame two general classes of Earth Observation missions have been identified to address user requirements (see e.g. ESA, 1995), namely Earth Watch and Earth Explorer missions. One of the candidate Earth Explorer Missions selected for Phase A study is the Atmospheric Dynamics Mission which is intended to exploit a Doppler wind lidar, ALADIN, to measure winds in clear air (ESA, 1995 and ESA, 1996). It is being studied as a candidate for flight on the International Space Station (ISS) as an externally attached payload. The primary, long-term objective of the Atmospheric Dynamics Mission is to provide observations of wind profiles (e.g. radial wind component). Such data would be assimilated into numerical forecasting models leading to an improvement in objective analyses and hence in Numerical Weather Prediction. The mission would also provide data needed to address some of the key concerns of the World Climate Research Programme (WCRP) i.e. quantification of climate variability, validation and improvement of numerical models and process studies relevant to climate change. The newly acquired data would also help realize some of the objectives of the Global Climate Observing System (GCOS)

  9. The Sturgeon Falls paleosol and the composition of the atmosphere 1.1 Ga BP

    NASA Technical Reports Server (NTRS)

    Zbinden, E. A.; Holland, H. D.; Feakes, C. R.

    1988-01-01

    A paleosol is exposed along the north bank of the Sturgeon River, some 25 km SW of Baraga, Michigan. The paleosol was developed on hydrothermally altered Keweenawan basalt and is overlain by the Jacobsville sandstone. Textures, mineralogy, and chemical composition change gradually upwards from unweathered metabasalt, through the paleosol, to the contact of the paleosol with the Jacobsville sandstone. Many of these changes are similar to those in modern soils developed on basaltic rocks. However, K has clearly been added to the paleosol, probably by solutions which had equilibrated with K-feldspar in the Jacobsville sandstone. The Keweenawan basalt was oxidized quite extensively during its conversion to greenstone. During weathering, the remaining Fe2+ was oxidized to Fe3+ and was retained in the paleosol. The composition of the parent greenstone and its change during weathering can be used to define an approximate lower limit to the ratio of the O2 pressure to the CO2 pressure in the atmosphere during the formation of the paleosol [formula: see text]. Free O2 must have been present in the atmosphere 1.1 Ga ago, but its partial pressure could have been 10(3) times lower than in the atmosphere today.

  10. Laboratory analogues simulating Titan's atmospheric aerosols: Compared chemical compositions of grains and thin films

    NASA Astrophysics Data System (ADS)

    Carrasco, Nathalie; Jomard, François; Vigneron, Jackie; Etcheberry, Arnaud; Cernogora, Guy

    2016-09-01

    Two sorts of solid organic samples can be produced in laboratory experiments simulating Titan's atmospheric reactivity: grains in the volume and thin films on the reactor walls. We expect that grains are more representative of Titan's atmospheric aerosols, but films are used to provide optical indices for radiative models of Titan's atmosphere. The aim of the present study is to address if these two sorts of analogues are chemically equivalent or not, when produced in the same N2-CH4 plasma discharge. The chemical compositions of both these materials are measured by using elemental analysis, XPS analysis and Secondary Ion Mass Spectrometry. The main parameter probed is the CH4/N2 ratio to explore various possible chemical regimes. We find that films are homogeneous but significantly less rich in nitrogen and hydrogen than grains produced in the same experimental conditions. This surprising difference in their chemical compositions could be explained by the efficient etching occurring on the films, which stay in the discharge during the whole plasma duration, whereas the grains are ejected after a few minutes. The higher nitrogen content in the grains possibly involves a higher optical absorption than the one measured on the films, with a possible impact on Titan's radiative models.

  11. Towards an energy-conserving quasi-hydrostatic deep-atmosphere dynamical core

    NASA Astrophysics Data System (ADS)

    Tort, Marine; Dubos, Thomas

    2014-05-01

    Towards an energy-conserving quasi-hydrostatic deep-atmosphere dynamical core Marine Tort1 & Thomas Dubos1 1 Laboratoire Météorologique Dynamique, Ecole Polytechnique, Palaiseau, FRANCE Atmosphere dynamics of our planet is quite well described by traditional primitive equations based on the so-called shallow-atmosphere approximation. Thus, the model is dynamically consistent (in the sense that it possesses conservation principles for mass, energy, potential vorticity and angular momentum) when certain metric terms and the cosφ Coriolis terms are neglected (Phillips, 1966). Nevertheless, to simulate planetary atmospheres, the shallow-atmosphere approximation should be relaxed because of the low planet radius (such as Titan) or the depth of their atmospheres (such as Jupiter or Saturne). Non-traditional terms have some dynamical effects (Gerkema and al., 2008) but they are little-known and rarely integrated into general circulation dynamical cores (Wood and Staniforth, 2002). As an example, the french GCM of the Laboratoire Météorologique Dynamique (LMD-Z) integrates the traditional primitive equations discretized from their curl (vector-invariant) form based on a finite different scheme whose conserves exactly potential vorticity (Sadourny, 1975a,b). We considered an orthogonal curvilinear system and we first derived a curl form of global, deep-atmosphere quasi-hydrostatic model in which prognostic variable is absolute axial momentum instead of relative velocity vector. Given the close relationship between the curl form and Hamiltonian formulation of the previous equations, we generalized Sadourny's energy-conserving formulation by discretizing the Poisson bracket and the energy themselves (Salmon, 1983; Gassmann, 2013). The substantial computing infrastructure of the dynamical core is the same but the modification of the hydrostatic balance requires a mass-based vertical coordinate (Wood and Staniforth, 2003). The new discretization has been implemented into

  12. Dynamic Response and Simulations of Nanoparticle-Enhanced Composites

    DTIC Science & Technology

    2007-11-15

    34Experimental and finite element analysis of pultruded glass-graphite/ epoxy hybrids in axial and flexural modes of vibration". Journal of Composite... flexural /extensional dynamic modulus, damping, low-velocity impact and high-strain (Hopkinson bar) response of nylon 6,6 thermoplastic reinforced with multi...enhanced face sheets; forming structures that offer optimal flexural rigidity, vibration damping and impact energy absorption along with reduced weight

  13. Impact of atmospheric circulation fluctuations on the zoobenthos dynamics in the Sea of Azov

    NASA Astrophysics Data System (ADS)

    Matishov, G. G.; Gargopa, Yu. M.; Sarvilina, S. V.

    2010-02-01

    The impact of atmospheric circulation fluctuations (Vangengeim’s classification) on the zoobenthos dynamics in the Sea of Azov was studied. The “western” circulation processes lead to zoobenthos biomass decrease, and the opposite pattern was observed when “eastern” circulation processes prevail. A quasiperiodicity with 3-7 to 10-15 year cycles is revealed for the zoobenthos biomass dynamics. These changes are closely connected with the climatically induced increase of the zoobenthos biomass in the Sea of Azov.

  14. Dynamic microbuckling model for compressive strength of polymeric composites

    NASA Astrophysics Data System (ADS)

    Tsai, Jia-Lin

    Dynamic compressive strength of off-axis fiber composites in the form of fiber microbuckling was studied. Both fiber misalignments and material nonlinearity were taken into account in this study. A fiber microbuckling model derived using micromechanics based on the nonlinear behavior of the matrix was extended to include the strain rate effect. The critical microbuckling stress was found to be the same as that in Rosen's bifurcation analysis except that elastic shear modulus was replaced by the tangent shear modulus of composites. The tangent shear modulus was rate dependent and described using an elastic/viscoplastic constitutive model. The viscoplasticity model was verified to provide stress-strain relations at high strain rates. S2/8552 glass/epoxy unidirectional composites with small off-axis angles were tested to failure at various strain rates. For strain rates below 1/sec, the compression tests were conducted on an MTS machine, while higher strain rate tests were carried out using a Split Hopkinson Pressure Bar. Comparison with experimental data indicated that the dynamic microbuckling model was suitable for prediction of compressive strengths at different strain rates. The compressive strength of multi-directional laminates was characterized. Laminate plate theory and finite element analysis with material nonlinearity were employed for laminar stress analysis. The critical failure stress in the 0° ply was estimated using the microbuckling model. Based on that, the compressive strength of composite laminates was predicted. The model predictions were compared with experimental data and good agreements were revealed.

  15. Chemical composition measurements of the atmosphere of Jupiter with the Galileo Probe mass spectrometer

    NASA Technical Reports Server (NTRS)

    Niemann, H. B.; Atreya, S. K.; Carignan, G. R.; Donahue, T. M.; Haberman, J. A.; Harpold, D. N.; Hartle, R. E.; Hunten, D. M.; Kasprzak, W. T.; Mahaffy, P. R.; Owen, T. C.; Spencer, N. W.

    1998-01-01

    The Galileo Probe entered the atmosphere of Jupiter on December 7, 1995. Measurements of the chemical and isotopic composition of the Jovian atmosphere were obtained by the mass spectrometer during the descent over the 0.5 to 21 bar pressure region over a time period of approximately 1 hour. The sampling was either of atmospheric gases directly introduced into the ion source of the mass spectrometer through capillary leaks or of gas, which had been chemically processed to enhance the sensitivity of the measurement to trace species or noble gases. The analysis of this data set continues to be refined based on supporting laboratory studies on an engineering unit. The mixing ratios of the major constituents of the atmosphere hydrogen and helium have been determined as well as mixing ratios or upper limits for several less abundant species including: methane, water, ammonia, ethane, ethylene, propane, hydrogen sulfide, neon, argon, krypton, and xenon. Analysis also suggests the presence of trace levels of other 3 and 4 carbon hydrocarbons, or carbon and nitrogen containing species, phosphine, hydrogen chloride, and of benzene. The data set also allows upper limits to be set for many species of interest which were not detected. Isotope ratios were measured for 3He/4He, D/H, 13C/12C, 20Ne/22Ne, 38Ar/36Ar and for isotopes of both Kr and Xe.

  16. Aerosol composition and microstructure in the smoky atmosphere of Moscow during the August 2010 extreme wildfires

    NASA Astrophysics Data System (ADS)

    Popovicheva, O. B.; Kistler, M.; Kireeva, E. D.; Persiantseva, N. M.; Timofeev, M. A.; Shoniya, N. K.; Kopeikin, V. M.

    2017-01-01

    This is a comprehensive study of the physicochemical characterization of multicomponent aerosols in the smoky atmosphere of Moscow during the extreme wildfires of August 2010 and against the background atmosphere of August 2011. Thermal-optical analysis, liquid and ion chromatography, IR spectroscopy, and electron microscopy were used to determine the organic content (OC) and elemental content (EC) of carbon, organic/inorganic and ionic compounds, and biomass burning markers (anhydrosaccharides and the potassium ion) and study the morphology and elemental composition of individual particles. It has been shown that the fires are characterized by an increased OC/EC ratio and high concentrations of ammonium, potassium, and sulfate ions in correlation with an increased content of levoglucosan as a marker of biomass burning. The organic compounds containing carbonyl groups point to the process of photochemical aging and the formation of secondary organic aerosols in the urban atmosphere when aerosols are emitted from forest fires. A cluster analysis of individual particles has indicated that when the smokiest atmosphere is characterized by prevailing soot/tar ball particles, which are smoke-emission micromarkers.

  17. The modern atmospheric background dust load: Recognition in Central Asian snowpack, and compositional constraints

    USGS Publications Warehouse

    Hinkley, T.; Pertsiger, F.; Zavjalova, L.

    1997-01-01

    Dusts in strata of snowpack in the Alai-Pamir range, Kirghizstan, Central Asia, have chemical compositions that are in the same restricted range as those of the dusts found in snowpacks at three other locations: central south Greenland, the St. Elias range (Alaska), and coastal Antarctica, where special-type local dust sources certainly cannot dominate. This similarity at the four widely separated sites appears to indicate that there is a modern atmospheric background dust that is the same on a regional, hemispheric, or global scale. The common compositional range is that of average crustal rock, or of moderately ferromagnesian volcanic rock. It is not that of carbonate, nor highly siliciceous rocks. Previously, the existence of an atmospheric background dust has been postulated only on the basis of its particle size distribution, and only from observations in polar regions. The present study partially determines the chemical composition of the background dust, and confirms its existence in snowpack at four localities worldwide, including the center of the earth's largest continent where dusts of local source have considerable influence. U.S. copyright. Published in 1997 by the American Geophysical Union.

  18. Day-of-week trends in carbonaceous aerosol composition in the urban atmosphere

    NASA Astrophysics Data System (ADS)

    Lough, G. C.; Schauer, J. J.; Lawson, D. R.

    The chemical composition of atmospheric particulate matter was measured at two sites near Los Angeles, California, over 3 weeks in July 2001, as part of the Gasoline/Diesel PM Split Study. Samples were composited for organic speciation analysis by day of week at each site to investigate weekly trends in chemical composition of the carbonaceous fraction of particulate matter. Observed weekly trends in elemental carbon (EC), hopanes, steranes, and polynuclear aromatic hydrocarbons (PAHs) indicate increased impacts of motor vehicle traffic on carbonaceous particulate matter concentrations on weekdays relative to weekends. Ambient average EC was approximately 4 times higher in the Friday samples than in Sunday samples at each site. Levoglucosan, a tracer species for biomass burning, and cholesterol, monopalmitin, and monostearin, tracers for food cooking operations, were all highest on Friday and lowest on Sunday. Late-week increases in aliphatic and aromatic diacids present in the particulate phase were also observed. Diacids in particulate matter have been seen to be indicators of secondary organic aerosol formation, and the day-of-week trend observed may be due to weekday increases in volatile precursor species present in the atmosphere.

  19. The dynamic response of carbon fiber-filled polymer composites

    NASA Astrophysics Data System (ADS)

    Dattelbaum, D. M.; Gustavsen, R. L.; Sheffield, S. A.; Stahl, D. B.; Scharff, R. J.; Rigg, P. A.; Furmanski, J.; Orler, E. B.; Patterson, B.; Coe, J. D.

    2012-08-01

    The dynamic (shock) responses of two carbon fiber-filled polymer composites have been quantified using gas gun-driven plate impact experimentation. The first composite is a filament-wound, highly unidirectional carbon fiber-filled epoxy with a high degree of porosity. The second composite is a chopped carbon fiber- and graphite-filled phenolic resin with little-to-no porosity. Hugoniot data are presented for the carbon fiber-epoxy (CE) composite to 18.6 GPa in the through-thickness direction, in which the shock propagates normal to the fibers. The data are best represented by a linear Rankine-Hugoniot fit: Us = 2.87 + 1.17 ×up(ρ0 = 1.536g/cm3). The shock wave structures were found to be highly heterogeneous, both due to the anisotropic nature of the fiber-epoxy microstructure, and the high degree of void volume. Plate impact experiments were also performed on a carbon fiber-filled phenolic (CP) composite to much higher shock input pressures, exceeding the reactants-to-products transition common to polymers. The CP was found to be stiffer than the filament-wound CE in the unreacted Hugoniot regime, and transformed to products near the shock-driven reaction threshold on the principal Hugoniot previously shown for the phenolic binder itself. [19] On-going research is focused on interrogating the direction-dependent dyanamic response and dynamic failure strength (spall) for the CE composite in the TT and 0∘ (fiber) directions.

  20. High-Order Shock-Capturing Methods for Modeling Dynamics of the Solar Atmosphere

    NASA Technical Reports Server (NTRS)

    Bryson, Steve; Kosovichev, Alexander; Levy, Doron

    2004-01-01

    We use one-dimensional high-order central shock capturing numerical methods to study the response of various model solar atmospheres to forcing at the solar surface. The dynamics of the atmosphere is modeled with the Euler equations in a variable-sized flux tube in the presence of gravity. We study dynamics of the atmosphere suggestive of spicule formation and coronal oscillations. These studies are performed on observationally-derived model atmospheres above the quiet sun and above sunspots. To perform these simulations, we provide a new extension of existing second- and third- order shock-capturing methods to irregular grids. We also solve the problem of numerically maintaining initial hydrostatic balance via the introduction of new variables in the model equations and a careful initialization mechanism. We find several striking results: all model atmospheres respond to a single impulsive perturbation with several strong shock waves consistent with the rebound-shock model. These shock waves lift material and the transition region well into the initial corona, and the sensitivity of this lift to the initial impulse depends non-linearly on the details of the atmosphere model. We also reproduce an observed 3-minute coronal oscillation above sunspots compared to 5-minute oscillations above the quiet sun.

  1. Study of atmospheric dynamics and pollution in the coastal area of English Channel using clustering technique

    NASA Astrophysics Data System (ADS)

    Sokolov, Anton; Dmitriev, Egor; Delbarre, Hervé; Augustin, Patrick; Gengembre, Cyril; Fourmenten, Marc

    2016-04-01

    The problem of atmospheric contamination by principal air pollutants was considered in the industrialized coastal region of English Channel in Dunkirk influenced by north European metropolitan areas. MESO-NH nested models were used for the simulation of the local atmospheric dynamics and the online calculation of Lagrangian backward trajectories with 15-minute temporal resolution and the horizontal resolution down to 500 m. The one-month mesoscale numerical simulation was coupled with local pollution measurements of volatile organic components, particulate matter, ozone, sulphur dioxide and nitrogen oxides. Principal atmospheric pathways were determined by clustering technique applied to backward trajectories simulated. Six clusters were obtained which describe local atmospheric dynamics, four winds blowing through the English Channel, one coming from the south, and the biggest cluster with small wind speeds. This last cluster includes mostly sea breeze events. The analysis of meteorological data and pollution measurements allows relating the principal atmospheric pathways with local air contamination events. It was shown that contamination events are mostly connected with a channelling of pollution from local sources and low-turbulent states of the local atmosphere.

  2. Measurement of atmospheric composition by the ATMOS instrument from Table Mountain Observatory

    NASA Technical Reports Server (NTRS)

    Gunson, Michael R.; Irion, Fredrick W.

    1991-01-01

    Following its first flight on board the Space Shuttle 'Challenger' as part of the Spacelab 3 payload, the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument has been operated at the Jet Propulsion Laboratory's Table Mountain Observatory (TMO; 34.4 deg N, 117.7 deg W, 2.23 km altitude) in the San Gabriel Mountains of Southern California. With the delay in the resumption of regular Shuttle flights, ATMOS has acquired a large number of high-quality, high-resolution infrared solar absorption spectra, spanning a period between late-1985 and mid-1990. These spectra are being analyzed to derive the column abundances of several atmospheric species including O3, HCl, HF, and HNO3. Although limited in temporal coverage, the preliminary results for these gases are discussed here in the context of the requirement and contribution to be made by similar instruments in detecting long term changes in stratospheric composition.

  3. The composition of the primitive atmosphere and the synthesis of organic compounds on the early Earth

    NASA Astrophysics Data System (ADS)

    Bada, J. L.; Miller, S. L.

    The generally accepted theory for the origin of life on the Earth requires that a large variety of organic compounds be present to form the first living organisms and to provide the energy sources for primitive life either directly or through various fermentation reactions. This can provide a strong constraint on discussions of the formation of the Earth and on the composition of the primitive atmosphere. In order for substantial amounts of organic compounds to have been present on the prebiological Earth, certain conditions must have existed. There is a large body of literature on the prebiotic synthesis of organic compounds in various postulated atmospheres. In this mixture of abiotically synthesized organic compounds, the amino acids are of special interest since they are utilized by modern organisms to synthesize structural materials and a large array of catalytic peptides.

  4. The composition of the primitive atmosphere and the synthesis of organic compounds on the early Earth

    NASA Technical Reports Server (NTRS)

    Bada, J. L.; Miller, S. L.

    1985-01-01

    The generally accepted theory for the origin of life on the Earth requires that a large variety of organic compounds be present to form the first living organisms and to provide the energy sources for primitive life either directly or through various fermentation reactions. This can provide a strong constraint on discussions of the formation of the Earth and on the composition of the primitive atmosphere. In order for substantial amounts of organic compounds to have been present on the prebiological Earth, certain conditions must have existed. There is a large body of literature on the prebiotic synthesis of organic compounds in various postulated atmospheres. In this mixture of abiotically synthesized organic compounds, the amino acids are of special interest since they are utilized by modern organisms to synthesize structural materials and a large array of catalytic peptides.

  5. Future possibilities in objective analysis and data assimilation for atmospheric dynamics

    NASA Technical Reports Server (NTRS)

    Ghil, M.

    1985-01-01

    The role that dynamics plays in estimating the state of the atmosphere from incomplete and noisy data is reviewed. Objective analysis represents an attempt at relying mostly on the data and minimizing the role of dynamics in the estimation. Data assimilation tries to balance properly the roles of dynamical and observational information. Sequential estimation is presented as the proper framework for understanding this balance, and the Kalman filter as the ideal, optimal procedure for data assimilation. The optimal filter computes forecast error covariances of a given atmospheric model exactly, and hence data assimilation should be closely connected with predictability studies. This connection is described, and consequences drawn for currently active areas of the atmospheric and related sciences, namely, mesoscale meteorology, long range forecasting, and upper ocean dynamics. Possibilities offered by judicious data assimilation in understanding barotropic adjustment, a phenomenon that appears to play a crucial role in atmospheric behavior on the scale of weeks to months, and hence in long range forecasting are addressed.

  6. The Stratospheric Wind Ingrared Limb Sounder: Investigation of atmospheric dynamics and transport from Eos

    NASA Technical Reports Server (NTRS)

    Mccleese, D. J.

    1992-01-01

    The Stratospheric Wind Infrared Limb Sounder (SWIRLS) is one of the instruments in the atmospheric sounder package to be flown by NASA on the Earth Observing System (EOS) B platform in the late 1990's. SWIRLS is designed to measure the horizontal vector wind field, atmospheric temperature, and the abundances and distributions of ozone and nitrous oxide in the middle atmosphere. These measurements will constitute a dynamical climatology of the stratosphere covering time scales ranging from diurnal to interannual. In addition, the SWIRLS investigation will quantify the physical mechanisms responsible for the structure and variations of stratospheric circulation and temperature fields, including the transport of species, particularly ozone, heat and momentum. Existing data sets lack the combination of accuracy, global and temporal coverage, spatial resoultion and simultaneity required to distinguish unambiguosly between the roles of dynamical and chemical processes in determining the current distribution of ozone and its evolution in the future. The measurement objectives, measurement approach, and instrumentation of SWIRLS is described.

  7. Carbon Observations from Geostationary Earth Orbit as Part of an Integrated Observing System for Atmospheric Composition

    NASA Astrophysics Data System (ADS)

    Edwards, D. P.

    2015-12-01

    This presentation describes proposed satellite carbon measurements from the CHRONOS mission. The primary goal of this experiment is to measure the atmospheric pollutants carbon monoxide (CO) and methane (CH4) from geostationary orbit, with hourly observations of North America at high spatial resolution. CHRONOS observations would provide measurements not currently available or planned as part of a surface, suborbital and satellite integrated observing system for atmospheric composition over North America. Carbon monoxide is produced by combustion processes such as urban activity and wildfires, and serves as a proxy for other combustion pollutants that are not easily measured. Methane has diverse anthropogenic sources ranging from fossil fuel production, animal husbandry, agriculture and waste management. The impact of gas exploration in the Western States of the USA and oil extraction from the Canadian tar sands will be particular foci of the mission, as will the poorly-quantified natural CH4 emissions from wetlands and thawing permafrost. In addition to characterizing pollutant sources, improved understanding of the domestic CH4 budget is a priority for policy decisions related to short-lived climate forcers. A primary motivation for targeting CO is its value as a tracer of atmospheric pollution, and CHRONOS measurements will provide insight into local and long-range transport across the North American continent, as well as the processes governing the entrainment and venting of pollution in and out of the planetary boundary layer. As a result of significantly improved characterization of diurnal changes in atmospheric composition, CHRONOS observations will find direct societal applications for air quality regulation and forecasting. We present a quantification of this expected improvement in the prediction of near-surface concentrations when CHRONOS measurements are used in Observation System Simulation Experiments (OSSEs). If CHRONOS and the planned NASA Earth

  8. Deciphering the atmospheric composition of WASP-12b: A comprehensive analysis of its dayside emission

    SciTech Connect

    Stevenson, Kevin B.; Bean, Jacob L.; Madhusudhan, Nikku; Harrington, Joseph

    2014-08-10

    WASP-12b was the first planet reported to have a carbon-to-oxygen ratio (C/O) greater than one in its dayside atmosphere. However, recent work to further characterize its atmosphere and confirm its composition has led to incompatible measurements and divergent conclusions. Additionally, the recent discovery of stellar binary companions ∼1'' from WASP-12 further complicates the analyses and subsequent interpretations. We present a uniform analysis of all available Hubble and Spitzer Space Telescope secondary-eclipse data, including previously unpublished Spitzer measurements at 3.6 and 4.5 μm. The primary controversy in the literature has centered on the value and interpretation of the eclipse depth at 4.5 μm. Our new measurements and analyses confirm the shallow eclipse depth in this channel, as first reported by Campo and collaborators and used by Madhusudhan and collaborators to infer a carbon-rich composition. To explain WASP-12b's observed dayside emission spectrum, we implemented several recent retrieval approaches. We find that when we exclude absorption due to C{sub 2}H{sub 2} and HCN, which are not universally considered in the literature, our models require implausibly large atmospheric CO{sub 2} abundances, regardless of the C/O. By including C{sub 2}H{sub 2} and HCN in our models, we find that a physically plausible carbon-rich solution achieves the best fit to the available photometric and spectroscopic data. In comparison, the best-fit oxygen-rich models have abundances that are inconsistent with the chemical equilibrium expectations for hydrogen-dominated atmospheres and are 670 times less probable. Our best-fit solution is also 7.3 × 10{sup 6} times more probable than an isothermal blackbody model.

  9. Tropical Pacific internal atmospheric dynamics and resolution in a coupled GCM

    NASA Astrophysics Data System (ADS)

    Lopez, Hosmay; Kirtman, Ben P.

    2015-01-01

    A noise reduction technique, namely the interactive ensemble (IE) approach is adopted to reduce noise at the air-sea interface due to internal atmospheric dynamics in a state-of-the-art coupled general circulation model (CGCM). The IE technique uses multiple realization of atmospheric general circulation models coupled to a single ocean general circulation model. The ensembles mean fluxes from the atmospheric simulations are communicated to the ocean component. Each atmospheric simulation receives the same SST coming from the ocean component. The only difference among the atmospheric simulations comes from perturbed initial conditions, thus the atmospheric states are, in principle synoptically independent. The IE technique can be used to better understand the importance of weather noise forcing of natural variability such as El Niño Southern Oscillation (ENSO). To study the impact of weather noise and resolution in the context of a CGCM, two IE experiments are performed at different resolutions. Atmospheric resolution is an important issue since the noise statistics will depend on the spatial scales resolved. A simple formulation to extract atmospheric internal variability is presented. The results are compared to their respective control cases where internal atmospheric variability is left unchanged. The noise reduction has a major impact on the coupled simulation and the magnitude of this effect strongly depends on the horizontal resolution of the atmospheric component model. Specifically, applying the noise reduction technique reduces the overall climate variability more effectively at higher resolution. This suggests that "weather noise" is more important in sustaining climate variability as resolution increases. ENSO statistics, dynamics, and phase asymmetry are all modified by the noise reduction, in particular ENSO becomes more regular with less phase asymmetry when noise is reduced. All these effects are more marked for the higher resolution case. In

  10. The stable isotope compositions of mercury in atmospheric particles (PM10) from Paris (France) and vicinity

    NASA Astrophysics Data System (ADS)

    Widory, D.; Petelet-Giraud, E.; Johnson, T.; Quétel, C.; Snell, J.; van Bocxstaele, M.; Bullen, T. D.

    2010-12-01

    Solid mercury (Hg) in atmospheric particles in the environment can be derived from a variety of primary sources and cycled through numerous secondary processes, complicating identification of its origin. Using the PM10 fraction of aerosols from Paris and vicinity, we investigated the possibility that Hg stable isotope compositions could help identify the origins of atmospheric Hg and processes affecting the atmospheric Hg budget. Characterization of Hg isotope compositions of emissions from the different potential sources (e.g. waste incinerators, coal-fired power plants, metal refining plants, road traffic, heating sources and volcanic gases) shows that those containing Hg are clearly discriminated by specific Hg isotope signatures. PM10 were sampled in three different locations: A) downtown Paris, characterized by diffuse pollution, B) nearby suburb of the city, close to suspected Hg emitters, and C) in distant suburb of the city, having only a few industrial activities in the area. Results indicate that Hg in most of the PM10 samples is explained by binary mixings. The mixing end-members include at least two distinct sources at low Hg concentrations in the aerosols, compatible with industrial activity. At high Hg concentration in the aerosols, the isotopes may likewise indicate two distinct sources with δ202Hg compositions of -4.1 and -11.4 ‰. This range is significantly less than that measured on the potential sources of Hg pollution, and may indicate secondary processes, such as gas to solid phase transfers. The occurrence of post-emission processes is reinforced by the strong correlations existing between these low δ202Hg and MIF Δ201Hg values.

  11. STABILITY AND DYNAMICS OF A FLUX ROPE FORMED VIA FLUX EMERGENCE INTO THE SOLAR ATMOSPHERE

    SciTech Connect

    An, J. M.; Magara, T. E-mail: magara@khu.ac.kr

    2013-08-10

    We study the stability and dynamics of a flux rope formed through the emergence of a twisted magnetic flux tube into the solar atmosphere. A three-dimensional magnetohydrodynamic simulation has been performed to investigate several key factors affecting the dynamics of the flux rope. The stability of the flux rope is examined by deriving the decay index of the coronal magnetic field surrounding the flux rope. We investigate a transition between the quasi-static and dynamic states of the flux rope through an analysis of the curvature and scale height of emerging magnetic field. A practical application of this analysis for global eruptions is also considered.

  12. A moist aquaplanet variant of the Held-Suarez test for atmospheric model dynamical cores

    NASA Astrophysics Data System (ADS)

    Thatcher, Diana R.; Jablonowski, Christiane

    2016-04-01

    A moist idealized test case (MITC) for atmospheric model dynamical cores is presented. The MITC is based on the Held-Suarez (HS) test that was developed for dry simulations on "a flat Earth" and replaces the full physical parameterization package with a Newtonian temperature relaxation and Rayleigh damping of the low-level winds. This new variant of the HS test includes moisture and thereby sheds light on the nonlinear dynamics-physics moisture feedbacks without the complexity of full-physics parameterization packages. In particular, it adds simplified moist processes to the HS forcing to model large-scale condensation, boundary-layer mixing, and the exchange of latent and sensible heat between the atmospheric surface and an ocean-covered planet. Using a variety of dynamical cores of the National Center for Atmospheric Research (NCAR)'s Community Atmosphere Model (CAM), this paper demonstrates that the inclusion of the moist idealized physics package leads to climatic states that closely resemble aquaplanet simulations with complex physical parameterizations. This establishes that the MITC approach generates reasonable atmospheric circulations and can be used for a broad range of scientific investigations. This paper provides examples of two application areas. First, the test case reveals the characteristics of the physics-dynamics coupling technique and reproduces coupling issues seen in full-physics simulations. In particular, it is shown that sudden adjustments of the prognostic fields due to moist physics tendencies can trigger undesirable large-scale gravity waves, which can be remedied by a more gradual application of the physical forcing. Second, the moist idealized test case can be used to intercompare dynamical cores. These examples demonstrate the versatility of the MITC approach and suggestions are made for further application areas. The new moist variant of the HS test can be considered a test case of intermediate complexity.

  13. Determination of the isotopic composition of atmospheric methane and its application in the Antarctic

    NASA Technical Reports Server (NTRS)

    Lowe, David C.; Brenninkmeijer, Carl A. M.; Tyler, Stanley C.; Dlugkencky, Edward J.

    1991-01-01

    A procedure for establishing the C-13/C-12 ratio and the C-14 abundance in the atmospheric methane is discussed. The method involves air sample collection, measurement of the methane mixing ratio by gas chromotography followed by quantitative conversion of the methane in the air samples to CO2 and H2O, and analysis of the resulting CO2 for the C-13/C-12 ratio by stable isotope ratio mass spectrometry and measurement of C-14 content by accelerator mass spectrometry. The carbon isotropic composition of methane in air collected at Baring Head, New Zealand, and in air collected on aircraft flights between New Zealand and Antarctica is determined by the method, and no gradient in the composition between Baring Head and the South Pole station is found. As the technique is refined, and more data is gathered, small seasonal and long-term variations in C-13 are expected to be resolved.

  14. The puzzling chemical composition of GJ 436B'S atmosphere: Influence of tidal heating on the chemistry

    SciTech Connect

    Agúndez, Marcelino; Selsis, Franck; Venot, Olivia; Iro, Nicolas

    2014-02-01

    The dissipation of the tidal energy deposited on eccentric planets may induce a heating of the planet that affects its atmospheric thermal structure. Here we study the influence of tidal heating on the atmospheric composition of the eccentric (e = 0.16) 'hot Neptune' GJ 436b, for which inconclusive chemical abundances are retrieved from multiwavelength photometric observations carried out during primary transit and secondary eclipse. We build up a one-dimensional model of GJ 436b's atmosphere in the vertical direction and compute the pressure-temperature and molecular abundances profiles for various plausible internal temperatures of the planet (up to 560 K) and metallicities (from solar to 100 times solar), using a radiative-convective model and a chemical model which includes thermochemical kinetics, vertical mixing, and photochemistry. We find that the CO/CH{sub 4} abundance ratio increases with metallicity and tidal heating, and ranges from 1/20 to 1000 within the ranges of metallicity and internal temperature explored. Water vapor locks most of the oxygen and reaches a very high abundance, whatever the metallicity and internal temperature of the planet. The CO{sub 2}/H{sub 2}O abundance ratio increases dramatically with metallicity, and takes values between 10{sup –5}-10{sup –4} with solar elemental abundances and ∼0.1 for a metallicity 100 times solar. None of the atmospheric models based on solid physical and chemical grounds provide a fully satisfactory agreement with available observational data, although the comparison of calculated spectra and observations seems to point to models with a high metallicity and efficient tidal heating, in which high CO/CH{sub 4} abundance ratios and warm temperatures in the dayside atmosphere are favored.

  15. Reduction Dynamics of Doped Ceria, Nickel Oxide, and Cermet Composites Probed Using In Situ Raman Spectroscopy

    PubMed Central

    Shearing, Paul R.; Brightman, Edward; Brett, Dan J. L.; Brandon, Nigel P.; Cohen, Lesley F.

    2016-01-01

    The redox properties of gadolinium doped ceria (CGO) and nickel oxide (NiO) composite cermets underpin the operation of solid oxide electrochemical cells. Although these systems have been widely studied, a full comprehension of the reaction dynamics at the interface of these materials is lacking. Here, in situ Raman spectroscopic monitoring of the redox cycle is used to investigate the interplay between the dynamic and competing processes of hydrogen spillover and water dissociation on the doped ceria surface. In order to elucidate these mechanisms, the redox process in pure CGO and NiO is studied when exposed to wet and dry hydrogen and is compared to the cermet behavior. In dry hydrogen, CGO reduces relatively rapidly via a series of intermediate phases, while NiO reduces via a single‐step process. In wet reducing atmospheres, however, the oxidation state of pure CGO is initially stabilized due to the dissociation of water by reduced Ce(III) and subsequent incorporation of oxygen into the structure. In the reduction process involving the composite cermet, the close proximity of the NiO improves the efficiency and speed of the composite reduction process. Although NiO is already incorporated into working cells, these observations suggest direct routes to further improve cell performance. PMID:27595058

  16. Reduction Dynamics of Doped Ceria, Nickel Oxide, and Cermet Composites Probed Using In Situ Raman Spectroscopy.

    PubMed

    Maher, Robert C; Shearing, Paul R; Brightman, Edward; Brett, Dan J L; Brandon, Nigel P; Cohen, Lesley F

    2016-01-01

    The redox properties of gadolinium doped ceria (CGO) and nickel oxide (NiO) composite cermets underpin the operation of solid oxide electrochemical cells. Although these systems have been widely studied, a full comprehension of the reaction dynamics at the interface of these materials is lacking. Here, in situ Raman spectroscopic monitoring of the redox cycle is used to investigate the interplay between the dynamic and competing processes of hydrogen spillover and water dissociation on the doped ceria surface. In order to elucidate these mechanisms, the redox process in pure CGO and NiO is studied when exposed to wet and dry hydrogen and is compared to the cermet behavior. In dry hydrogen, CGO reduces relatively rapidly via a series of intermediate phases, while NiO reduces via a single-step process. In wet reducing atmospheres, however, the oxidation state of pure CGO is initially stabilized due to the dissociation of water by reduced Ce(III) and subsequent incorporation of oxygen into the structure. In the reduction process involving the composite cermet, the close proximity of the NiO improves the efficiency and speed of the composite reduction process. Although NiO is already incorporated into working cells, these observations suggest direct routes to further improve cell performance.

  17. Semi-volatile inorganic species: importance for atmospheric chemical composition on diurnal and seasonal timescales

    NASA Astrophysics Data System (ADS)

    Pearce, Hana; Mann, Graham; Arnold, Stephen; O'Connor, Fiona; Benduhn, Francois; Rumbold, Steven; Pringle, Kirsty

    2016-04-01

    Nitrate aerosol has become an important driver of reduced European air quality and climate forcing, following reductions in sulphate precursor emissions since the 1980s, and is expected to be more influential in future decades. Measurements from the European Integrated Project on Aerosol and Cloud Climate Air Quality Interactions (EUCAARI) field campaign have shown that semi-volatile aerosol species such as ammonium nitrate can comprise a major component of the sub-micron particulate matter, particularly in high pollution episodes. This presentation will assess the contribution of semi-volatile inorganic aerosol to diurnal and seasonal cycles in atmospheric chemical composition over Europe. We use the UM-UKCA composition-climate model, including the GLOMAP interactive aerosol microphysics module and a recently developed 'hybrid' dissolution solver (HyDis) to accurately represent size-resolved partitioning of ammonia and nitric acid to the particle phase. In particular, we evaluate simulated size-resolved composition variations over Europe through the diurnal cycle, comparing hourly model output to Aerosol Mass Spectrometer observations at several sites during 2008. We will present the results of this composition analysis, in addition to model evaluation from comparisons with European Monitoring for Environmental Protection (EMEP) network and EUCAARI field campaign observations.

  18. Strength and dynamic characteristics analyses of wound composite axial impeller

    NASA Astrophysics Data System (ADS)

    Wang, Jifeng; Olortegui-Yume, Jorge; Müller, Norbert

    2012-03-01

    A low cost, light weight, high performance composite material turbomachinery impeller with a uniquely designed blade patterns is analyzed. Such impellers can economically enable refrigeration plants to use water as a refrigerant (R718). A strength and dynamic characteristics analyses procedure is developed to assess the maximum stresses and natural frequencies of these wound composite axial impellers under operating loading conditions. Numerical simulation using FEM for two-dimensional and three-dimensional impellers was investigated. A commercially available software ANSYS is used for the finite element calculations. Analysis is done for different blade geometries and then suggestions are made for optimum design parameters. In order to avoid operating at resonance, which can make impellers suffer a significant reduction in the design life, the designer must calculate the natural frequency and modal shape of the impeller to analyze the dynamic characteristics. The results show that using composite Kevlar fiber/epoxy matrix enables the impeller to run at high tip speed and withstand the stresses, no critical speed will be matched during start-up and shut-down, and that mass imbalances of the impeller shall not pose a critical problem.

  19. Dynamic Mechanical Behavior of Nickel-Aluminum Reinforced Epoxy Composites

    NASA Astrophysics Data System (ADS)

    Martin, Morgana; Hanagud, Sathyanaraya; Thadhani, Naresh

    2005-07-01

    Epoxy-based composites reinforced with a mixture of micron-sized Ni and micron or nano-sized Al powders were fabricated as bulk materials by cast/curing. The structural/mechanical behavior of these materials was evaluated using elastic and plastic property measurements via static and dynamic compression tests performed on rod shaped samples. Reverse Taylor anvil-on-rod impact tests combined with velocity interferometry gave qualitative and quantitative information about the transient deformation and failure response of the composites. The material containing 20wt% epoxy and nano-sized Al powder showed the most superior mechanical properties in terms of elastic modulus, and static and dynamic compressive strength, and strain before fracture, as compared to the other reinforced cast materials. The results illustrate that nano-sized Al particles provide significant enhancement to strength of epoxy composites by dispersing in the epoxy and generating a nano-Al containing epoxy matrix with embedded Ni particles. Funding for this research was provided by AFOSR/MURI Grant No. F49620-02-1-0382.

  20. Multi-Scale Compositionality: Identifying the Compositional Structures of Social Dynamics Using Deep Learning

    PubMed Central

    Peng, Huan-Kai; Marculescu, Radu

    2015-01-01

    Objective Social media exhibit rich yet distinct temporal dynamics which cover a wide range of different scales. In order to study this complex dynamics, two fundamental questions revolve around (1) the signatures of social dynamics at different time scales, and (2) the way in which these signatures interact and form higher-level meanings. Method In this paper, we propose the Recursive Convolutional Bayesian Model (RCBM) to address both of these fundamental questions. The key idea behind our approach consists of constructing a deep-learning framework using specialized convolution operators that are designed to exploit the inherent heterogeneity of social dynamics. RCBM’s runtime and convergence properties are guaranteed by formal analyses. Results Experimental results show that the proposed method outperforms the state-of-the-art approaches both in terms of solution quality and computational efficiency. Indeed, by applying the proposed method on two social network datasets, Twitter and Yelp, we are able to identify the compositional structures that can accurately characterize the complex social dynamics from these two social media. We further show that identifying these patterns can enable new applications such as anomaly detection and improved social dynamics forecasting. Finally, our analysis offers new insights on understanding and engineering social media dynamics, with direct applications to opinion spreading and online content promotion. PMID:25830775

  1. Dynamic fracture of functionally graded magnetoelectroelastic composite materials

    NASA Astrophysics Data System (ADS)

    Stoynov, Y.; Dineva, P.

    2014-11-01

    The stress, magnetic and electric field analysis of multifunctional composites, weakened by impermeable cracks, is of fundamental importance for their structural integrity and reliable service performance. The aim is to study dynamic behavior of a plane of functionally graded magnetoelectroelastic composite with more than one crack. The coupled material properties vary exponentially in an arbitrary direction. The plane is subjected to anti-plane mechanical and in-plane electric and magnetic load. The boundary value problem described by the partial differential equations with variable coefficients is reduced to a non-hypersingular traction boundary integral equation based on the appropriate functional transform and frequency-dependent fundamental solution derived in a closed form by Radon transform. Software code based on the boundary integral equation method (BIEM) is developed, validated and inserted in numerical simulations. The obtained results show the sensitivity of the dynamic stress, magnetic and electric field concentration in the cracked plane to the type and characteristics of the dynamic load, to the location and cracks disposition, to the wave-crack-crack interactions and to the magnitude and direction of the material gradient.

  2. Dynamic fracture of functionally graded magnetoelectroelastic composite materials

    SciTech Connect

    Stoynov, Y.; Dineva, P.

    2014-11-12

    The stress, magnetic and electric field analysis of multifunctional composites, weakened by impermeable cracks, is of fundamental importance for their structural integrity and reliable service performance. The aim is to study dynamic behavior of a plane of functionally graded magnetoelectroelastic composite with more than one crack. The coupled material properties vary exponentially in an arbitrary direction. The plane is subjected to anti-plane mechanical and in-plane electric and magnetic load. The boundary value problem described by the partial differential equations with variable coefficients is reduced to a non-hypersingular traction boundary integral equation based on the appropriate functional transform and frequency-dependent fundamental solution derived in a closed form by Radon transform. Software code based on the boundary integral equation method (BIEM) is developed, validated and inserted in numerical simulations. The obtained results show the sensitivity of the dynamic stress, magnetic and electric field concentration in the cracked plane to the type and characteristics of the dynamic load, to the location and cracks disposition, to the wave-crack-crack interactions and to the magnitude and direction of the material gradient.

  3. Realistic Modeling of Multi-Scale MHD Dynamics of the Solar Atmosphere

    NASA Technical Reports Server (NTRS)

    Kitiashvili, Irina; Mansour, Nagi N.; Wray, Alan; Couvidat, Sebastian; Yoon, Seokkwan; Kosovichev, Alexander

    2014-01-01

    Realistic 3D radiative MHD simulations open new perspectives for understanding the turbulent dynamics of the solar surface, its coupling to the atmosphere, and the physical mechanisms of generation and transport of non-thermal energy. Traditionally, plasma eruptions and wave phenomena in the solar atmosphere are modeled by prescribing artificial driving mechanisms using magnetic or gas pressure forces that might arise from magnetic field emergence or reconnection instabilities. In contrast, our 'ab initio' simulations provide a realistic description of solar dynamics naturally driven by solar energy flow. By simulating the upper convection zone and the solar atmosphere, we can investigate in detail the physical processes of turbulent magnetoconvection, generation and amplification of magnetic fields, excitation of MHD waves, and plasma eruptions. We present recent simulation results of the multi-scale dynamics of quiet-Sun regions, and energetic effects in the atmosphere and compare with observations. For the comparisons we calculate synthetic spectro-polarimetric data to model observational data of SDO, Hinode, and New Solar Telescope.

  4. Effective low-order models for atmospheric dynamics and time series analysis.

    PubMed

    Gluhovsky, Alexander; Grady, Kevin

    2016-02-01

    The paper focuses on two interrelated problems: developing physically sound low-order models (LOMs) for atmospheric dynamics and employing them as novel time-series models to overcome deficiencies in current atmospheric time series analysis. The first problem is warranted since arbitrary truncations in the Galerkin method (commonly used to derive LOMs) may result in LOMs that violate fundamental conservation properties of the original equations, causing unphysical behaviors such as unbounded solutions. In contrast, the LOMs we offer (G-models) are energy conserving, and some retain the Hamiltonian structure of the original equations. This work examines LOMs from recent publications to show that all of them that are physically sound can be converted to G-models, while those that cannot lack energy conservation. Further, motivated by recent progress in statistical properties of dynamical systems, we explore G-models for a new role of atmospheric time series models as their data generating mechanisms are well in line with atmospheric dynamics. Currently used time series models, however, do not specifically utilize the physics of the governing equations and involve strong statistical assumptions rarely met in real data.

  5. The Dynamic Atmospheres of Carbon Rich Giants: Constraining Models Via Interferometry

    NASA Astrophysics Data System (ADS)

    Rau, Gioia; Hron, Josef; Paladini, Claudia; Aringer, Bernard; Eriksson, Kjell; Marigo, Paola

    2016-07-01

    Dynamic models for the atmospheres of C-rich Asymptotic Giant Branch stars are quite advanced and have been overall successful in reproducing spectroscopic and photometric observations. Interferometry provides independent information and is thus an important technique to study the atmospheric stratification and to further constrain the dynamic models. We observed a sample of six C-rich AGBs with the mid infrared interferometer VLTI/MIDI. These observations, combined with photometric and spectroscopic data from the literature, are compared with synthetic observables derived from dynamic model atmospheres (DMA, Eriksson et al. 2014). The SEDs can be reasonably well modelled and the interferometry supports the extended and multi-component structure of the atmospheres, but some differences remain. We discuss the possible reasons for these differences and we compare the stellar parameters derived from this comparison with stellar evolution models. Finally, we point out the high potential of MATISSE, the second generation VLTI instrument allowing interferometric imaging in the L, M, and N bands, for further progress in this field.

  6. Impact of rocket exhaust plumes on atmospheric composition and climate ― an overview

    NASA Astrophysics Data System (ADS)

    Voigt, Ch.; Schumann, U.; Graf, K.; Gottschaldt, K.-D.

    2013-03-01

    Rockets are the only direct anthropogenic emission sources into the upper atmosphere. Gaseous rocket emissions include CO, N2, H2, H2O, and CO2, while solid rocket motors (SRM) additionally inject significant amounts of aluminum oxide (Al2O3) particles and gaseous chlorine species into the atmosphere. These emissions strongly perturb local atmospheric trace gas and aerosol distributions. Here, previous aircraft measurements in various rocket exhaust plumes including several large space shuttle launch vehicles are compiled. The observed changes of the lower stratospheric composition in the near field are summarized. The injection of chlorine species and particles into the stratosphere can lead to ozone loss in rocket exhaust plumes. Local observations are compared with global model simulations of the effects of rocket emissions on stratospheric ozone concentrations. Large uncertainties remain concerning individual ozone loss reaction rates and the impact of small-scale plume effects on global chemistry. Further, remote sensing data from satellite indicate that rocket exhaust plumes regionally increase iron and water vapor concentrations in the mesosphere potentially leading to the formation of mesospheric clouds at 80- to 90-kilometer altitude. These satellite observations are summarized and the rocket emission inventory is compared with other natural and anthropogenic sources to the stratosphere such as volcanism, meteoritic material, and aviation.

  7. Atmospheric precipitation and chemical composition of an urban site, Guaíba hydrographic basin, Brazil

    NASA Astrophysics Data System (ADS)

    Migliavacca, D.; Teixeira, E. C.; Wiegand, F.; Machado, A. C. M.; Sanchez, J.

    The purpose of the present work was to study the chemical composition of bulk and wet atmospheric precipitation in the Guaíba Hydrographic Basin, in South Brazil. The samples were analyzed from January to December 2002 at three different stations, i.e., 8° Distrito and CEASA stations in the city of Porto Alegre, and Charqueadas station, located in the city of same name. The bulk and wet precipitation were analyzed for conductivity, pH, Cl -, NO 3-, F -, SO 42-, Na +, K +, Mg 2+, NH 4+, Ca 2+, Cu, Zn, Mn, Fe and Al. The pH values in the samples of atmospheric precipitation ranged between 4.75 and 7.45. The analysis of linear regression applied to the set of studied variables showed that neutralization occurred in samples of bulk and wet precipitation. It was found that the Cl present in samples of atmospheric precipitation originated from sea salts and anthropogenic sources. The principal components analysis (PCA) identified the main anthropogenic sources within the Guaíba Hydrographic Basin (GHB). Cluster analysis grouped the events identified for each station in the PCA in association with the meteorological data.

  8. Response of the global climate to changes in atmospheric chemical composition due to fossil fuel burning

    NASA Technical Reports Server (NTRS)

    Hameed, S.; Cess, R. D.; Hogan, J. S.

    1980-01-01

    Recent modeling of atmospheric chemical processes (Logan et al, 1978; Hameed et al, 1979) suggests that tropospheric ozone and methane might significantly increase in the future as the result of increasing anthropogenic emissions of CO, NO(x), and CH4 due to fossil fuel burning. Since O3 and CH4 are both greenhouse gases, increases in their concentrations could augment global warming due to larger future amounts of atmospheric CO2. To test the possible climatic impact of changes in tropospheric chemical composition, a zonal energy-balance climate model has been combined with a vertically averaged tropospheric chemical model. The latter model includes all relevant chemical reactions which affect species derived from H2O, O2, CH4, and NO(x). The climate model correspondingly incorporates changes in the infrared heating of the surface-troposphere system resulting from chemically induced changes in tropospheric ozone and methane. This coupled climate-chemical model indicates that global climate is sensitive to changes in emissions of CO, NO(x) and CH4, and that future increases in these emissions could augment global warming due to increasing atmospheric CO2.

  9. Atmospheric composition 1 million years ago from blue ice in the Allan Hills, Antarctica.

    PubMed

    Higgins, John A; Kurbatov, Andrei V; Spaulding, Nicole E; Brook, Ed; Introne, Douglas S; Chimiak, Laura M; Yan, Yuzhen; Mayewski, Paul A; Bender, Michael L

    2015-06-02

    Here, we present direct measurements of atmospheric composition and Antarctic climate from the mid-Pleistocene (∼1 Ma) from ice cores drilled in the Allan Hills blue ice area, Antarctica. The 1-Ma ice is dated from the deficit in (40)Ar relative to the modern atmosphere and is present as a stratigraphically disturbed 12-m section at the base of a 126-m ice core. The 1-Ma ice appears to represent most of the amplitude of contemporaneous climate cycles and CO2 and CH4 concentrations in the ice range from 221 to 277 ppm and 411 to 569 parts per billion (ppb), respectively. These concentrations, together with measured δD of the ice, are at the warm end of the field for glacial-interglacial cycles of the last 800 ky and span only about one-half of the range. The highest CO2 values in the 1-Ma ice fall within the range of interglacial values of the last 400 ka but are up to 7 ppm higher than any interglacial values between 450 and 800 ka. The lowest CO2 values are 30 ppm higher than during any glacial period between 450 and 800 ka. This study shows that the coupling of Antarctic temperature and atmospheric CO2 extended into the mid-Pleistocene and demonstrates the feasibility of discontinuously extending the current ice core record beyond 800 ka by shallow coring in Antarctic blue ice areas.

  10. Atmospheric composition 1 million years ago from blue ice in the Allan Hills, Antarctica

    PubMed Central

    Higgins, John A.; Kurbatov, Andrei V.; Spaulding, Nicole E.; Brook, Ed; Introne, Douglas S.; Chimiak, Laura M.; Yan, Yuzhen; Mayewski, Paul A.; Bender, Michael L.

    2015-01-01

    Here, we present direct measurements of atmospheric composition and Antarctic climate from the mid-Pleistocene (∼1 Ma) from ice cores drilled in the Allan Hills blue ice area, Antarctica. The 1-Ma ice is dated from the deficit in 40Ar relative to the modern atmosphere and is present as a stratigraphically disturbed 12-m section at the base of a 126-m ice core. The 1-Ma ice appears to represent most of the amplitude of contemporaneous climate cycles and CO2 and CH4 concentrations in the ice range from 221 to 277 ppm and 411 to 569 parts per billion (ppb), respectively. These concentrations, together with measured δD of the ice, are at the warm end of the field for glacial–interglacial cycles of the last 800 ky and span only about one-half of the range. The highest CO2 values in the 1-Ma ice fall within the range of interglacial values of the last 400 ka but are up to 7 ppm higher than any interglacial values between 450 and 800 ka. The lowest CO2 values are 30 ppm higher than during any glacial period between 450 and 800 ka. This study shows that the coupling of Antarctic temperature and atmospheric CO2 extended into the mid-Pleistocene and demonstrates the feasibility of discontinuously extending the current ice core record beyond 800 ka by shallow coring in Antarctic blue ice areas. PMID:25964367

  11. A moist aquaplanet variant of the Held–Suarez test for atmospheric model dynamical cores

    DOE PAGES

    Thatcher, Diana R.; Jablonowski, Christiane

    2016-04-04

    A moist idealized test case (MITC) for atmospheric model dynamical cores is presented. The MITC is based on the Held–Suarez (HS) test that was developed for dry simulations on “a flat Earth” and replaces the full physical parameterization package with a Newtonian temperature relaxation and Rayleigh damping of the low-level winds. This new variant of the HS test includes moisture and thereby sheds light on the nonlinear dynamics–physics moisture feedbacks without the complexity of full-physics parameterization packages. In particular, it adds simplified moist processes to the HS forcing to model large-scale condensation, boundary-layer mixing, and the exchange of latent and sensible heat betweenmore » the atmospheric surface and an ocean-covered planet. Using a variety of dynamical cores of the National Center for Atmospheric Research (NCAR)'s Community Atmosphere Model (CAM), this paper demonstrates that the inclusion of the moist idealized physics package leads to climatic states that closely resemble aquaplanet simulations with complex physical parameterizations. This establishes that the MITC approach generates reasonable atmospheric circulations and can be used for a broad range of scientific investigations. This paper provides examples of two application areas. First, the test case reveals the characteristics of the physics–dynamics coupling technique and reproduces coupling issues seen in full-physics simulations. In particular, it is shown that sudden adjustments of the prognostic fields due to moist physics tendencies can trigger undesirable large-scale gravity waves, which can be remedied by a more gradual application of the physical forcing. Second, the moist idealized test case can be used to intercompare dynamical cores. These examples demonstrate the versatility of the MITC approach and suggestions are made for further application areas. The new moist variant of the HS test can be considered a test case of intermediate complexity.« less

  12. Titan's surface composition and atmospheric transmission with solar occultation measurements by Cassini VIMS

    NASA Astrophysics Data System (ADS)

    Hayne, Paul O.; McCord, Thomas B.; Sotin, Christophe

    2014-11-01

    Solar occultation measurements by the Cassini Visual and Infrared Mapping Spectrometer (VIMS) reveal the near-infrared transmission of Titan's atmosphere down to an altitude of ∼40 km. By combining these observations with VIMS reflectance measurements of Titan's surface and knowledge of haze and gas opacity profiles from the Huygens probe, we constrain a simple model for the transfer of radiation in Titan's atmosphere in order to derive surface reflectance in the methane windows used for compositional analysis. The advantages of this model are twofold: (1) it is accurate enough to yield useful results, yet simple enough to be implemented in just a few lines of code, and (2) the model parameters are directly constrained by the VIMS occultation and on-planet measurements. We focus on the 2.0, 2.7, 2.8 and 5.0 μm windows, where haze opacity is minimized, and diagnostic vibrational bands exist for water ice and other candidate surface species. A particularly important result is the strong atmospheric attenuation at 2.7 μm compared to 2.8 μm, resulting in a reversal of apparent spectral slope in a compositionally diagnostic wavelength range. These results show that Titan's surface reflectance is much "bluer" and more closely matched by water ice than the uncorrected spectra would indicate, although the majority of Titan's surface has a spectrum consistent with mixtures (either intimate or areal) of water ice and haze particles precipitated from the atmosphere. Compositions of geologic units can be accurately modeled as mixtures ranging from predominantly water ice (Sinlap crater ejecta and margins of dark equatorial terrain) to predominantly organic-rich (Tui Regio and Hotei Regio), with particles in the size range ∼10-20 μm. In distinguishing between hypothesized formation mechanisms for Tui and Hotei Regio, their organic-rich composition favors a process that concentrates precipitated haze particles, such as playa lake evaporite deposition (Barnes, J.W., Bow

  13. Improving Throughput of the ACME Climate Model by Parallel Splitting Atmospheric Physics and Dynamics

    NASA Astrophysics Data System (ADS)

    Caldwell, P.; Taylor, M.

    2015-12-01

    If fluid dynamics and atmospheric physics parameterizations were computed in parallel, they could be calculated simultaneously on separate cores of a supercomputer. This would greatly increase model throughput for high-resolution simulations. Additionally, because atmospheric physics is embarrassingly parallel, more sophisticated physics parameterizations could be used without slowing simulations down by simply increasing the number of cores used. The downside to this approach is that it increases time-truncation error. In this presentation, we demonstrate that parallel splitting the ACME model and using a smaller timestep for physics results in faster, more accurate solutions.

  14. The Vega balloons - A tool for studying atmosphere dynamics on Venus

    NASA Technical Reports Server (NTRS)

    Kremnev, R. S.; Selivanov, A. S.; Linkin, V. M.; Lipatov, A. N.; Tarnoruder, I. IA.; Puchkov, V. I.; Kustodiev, V. D.; Shurupov, A. A.; Ragent, B.; Preston, R. A.

    1986-01-01

    The Vega balloon experiment, designed to measure the dynamics of the Venus atmosphere, comprised the balloons themselves, their gondolas with on-board sensors and radio transmitters, and the radio telescope network on the earth. The structures and the physical parameters of the balloon probe are described, together with the instruments on the gondola, designed for the measurements of the atmospheric pressure, temperature, and vertical wind flows, and illumination, as well as possible flashes of lightning. Consideration is also given to the formatting of the information flow for the individual parameters measured.

  15. Accelerated Testing of Polymeric Composites Using the Dynamic Mechanical Analyzer

    NASA Technical Reports Server (NTRS)

    Abdel-Magid, Becky M.; Gates, Thomas S.

    2000-01-01

    Creep properties of IM7/K3B composite material were obtained using three accelerated test methods at elevated temperatures. Results of flexural creep tests using the dynamic mechanical analyzer (DMA) were compared with results of conventional tensile and compression creep tests. The procedures of the three test methods are described and the results are presented. Despite minor differences in the time shift factor of the creep compliance curves, the DMA results compared favorably with the results from the tensile and compressive creep tests. Some insight is given into establishing correlations between creep compliance in flexure and creep compliance in tension and compression. It is shown that with careful consideration of the limitations of flexure creep, a viable and reliable accelerated test procedure can be developed using the DMA to obtain the viscoelastic properties of composites in extreme environments.

  16. SMA Hybrid Composites for Dynamic Response Abatement Applications

    NASA Technical Reports Server (NTRS)

    Turner, Travis L.

    2000-01-01

    A recently developed constitutive model and a finite element formulation for predicting the thermomechanical response of Shape Memory Alloy (SMA) hybrid composite (SMAHC) structures is briefly described. Attention is focused on constrained recovery behavior in this study, but the constitutive formulation is also capable of modeling restrained or free recovery. Numerical results are shown for glass/epoxy panel specimens with embedded Nitinol actuators subjected to thermal and acoustic loads. Control of thermal buckling, random response, sonic fatigue, and transmission loss are demonstrated and compared to conventional approaches including addition of conventional composite layers and a constrained layer damping treatment. Embedded SMA actuators are shown to be significantly more effective in dynamic response abatement applications than the conventional approaches and are attractive for combination with other passive and/or active approaches.

  17. Dynamic effects of interaction of composite projectiles with targets

    NASA Astrophysics Data System (ADS)

    Zakharov, V. M.

    2016-01-01

    The process of high-speed impact of projectiles against targets of finite thickness is experimentally investigated. Medium-hard steel plates are used as targets. The objective of this research is to carry out a comparative analysis of dynamic effects of interaction of various types of projectiles with targets, such as characteristics of destruction of the target, the state of the projectile behind the target, and particularities of the after-penetration stream of fragments after the target has been pierced. The projectiles are made of composites on the basis of tungsten carbide obtained by caking and the SHS-technology. To compare effectiveness of composite projectiles steel projectiles are used. Their effectiveness was estimated in terms of the ballistic limit. High density projectiles obtained by means of the SHS-technology are shown to produce results comparable in terms of the ballistic limit with high-strength projectiles that contain tungsten received by caking.

  18. Dynamic effects of interaction of composite projectiles with targets

    SciTech Connect

    Zakharov, V. M.

    2016-01-15

    The process of high-speed impact of projectiles against targets of finite thickness is experimentally investigated. Medium-hard steel plates are used as targets. The objective of this research is to carry out a comparative analysis of dynamic effects of interaction of various types of projectiles with targets, such as characteristics of destruction of the target, the state of the projectile behind the target, and particularities of the after-penetration stream of fragments after the target has been pierced. The projectiles are made of composites on the basis of tungsten carbide obtained by caking and the SHS-technology. To compare effectiveness of composite projectiles steel projectiles are used. Their effectiveness was estimated in terms of the ballistic limit. High density projectiles obtained by means of the SHS-technology are shown to produce results comparable in terms of the ballistic limit with high-strength projectiles that contain tungsten received by caking.

  19. Mixing ratio and carbon isotopic composition investigation of atmospheric CO2 in Beijing, China.

    PubMed

    Pang, Jiaping; Wen, Xuefa; Sun, Xiaomin

    2016-01-01

    The stable isotope composition of atmospheric CO2 can be used as a tracer in the study of urban carbon cycles, which are affected by anthropogenic and biogenic CO2 components. Continuous measurements of the mixing ratio and δ(13)C of atmospheric CO2 were conducted in Beijing from Nov. 15, 2012 to Mar. 8, 2014 including two heating seasons and a vegetative season. Both δ(13)C and the isotopic composition of source CO2 (δ(13)CS) were depleted in the heating seasons and enriched in the vegetative season. The diurnal variations in the CO2 mixing ratio and δ(13)C contained two peaks in the heating season, which are due to the effects of morning rush hour traffic. Seasonal and diurnal patterns of the CO2 mixing ratio and δ(13)C were affected by anthropogenic emissions and biogenic activity. Assuming that the primary CO2 sources at night (22:00-04:00) were coal and natural gas combustion during heating seasons I and II, an isotopic mass balance analysis indicated that coal combustion had average contributions of 83.83±14.11% and 86.84±12.27% and that natural gas had average contributions of 16.17±14.11% and 13.16±12.27%, respectively. The δ(13)C of background CO2 in air was the main error source in the isotopic mass balance model. Both the mixing ratio and δ(13)C of atmospheric CO2 had significant linear relationships with the air quality index (AQI) and can be used to indicate local air pollution conditions. Energy structure optimization, for example, reducing coal consumption, will improve the local air conditions in Beijing.

  20. Isotopic composition for source identification of mercury in atmospheric fine particles

    NASA Astrophysics Data System (ADS)

    Huang, Qiang; Chen, Jiubin; Huang, Weilin; Fu, Pingqing; Guinot, Benjamin; Feng, Xinbin; Shang, Lihai; Wang, Zhuhong; Wang, Zhongwei; Yuan, Shengliu; Cai, Hongming; Wei, Lianfang; Yu, Ben

    2016-09-01

    The usefulness of mercury (Hg) isotopes for tracing the sources and pathways of Hg (and its vectors) in atmospheric fine particles (PM2.5) is uncertain. Here, we measured Hg isotopic compositions in 30 potential source materials and 23 PM2.5 samples collected in four seasons from the megacity Beijing (China) and combined the seasonal variation in both mass-dependent fractionation (represented by the ratio 202Hg / 198Hg, δ202Hg) and mass-independent fractionation of isotopes with odd and even mass numbers (represented by Δ199Hg and Δ200Hg, respectively) with geochemical parameters and meteorological data to identify the sources of PM2.5-Hg and possible atmospheric particulate Hg transformation. All PM2.5 samples were highly enriched in Hg and other heavy metals and displayed wide ranges of both δ202Hg (-2.18 to 0.51 ‰) and Δ199Hg (-0.53 to 0.57 ‰), as well as small positive Δ200Hg (0.02 to 0.17 ‰). The results indicated that the seasonal variation in Hg isotopic composition (and elemental concentrations) was likely derived from variable contributions from anthropogenic sources, with continuous input due to industrial activities (e.g., smelting, cement production and coal combustion) in all seasons, whereas coal combustion dominated in winter and biomass burning mainly found in autumn. The more positive Δ199Hg of PM2.5-Hg in spring and early summer was likely derived from long-range-transported Hg that had undergone extensive photochemical reduction. The study demonstrated that Hg isotopes may be potentially used for tracing the sources of particulate Hg and its vectors in the atmosphere.

  1. Dynamics and predictability of a low-order wind-driven ocean-atmosphere coupled model

    NASA Astrophysics Data System (ADS)

    Vannitsem, Stéphane

    2014-04-01

    The dynamics of a low-order coupled wind-driven ocean-atmosphere system is investigated with emphasis on its predictability properties. The low-order coupled deterministic system is composed of a baroclinic atmosphere for which 12 dominant dynamical modes are only retained (Charney and Straus in J Atmos Sci 37:1157-1176, 1980) and a wind-driven, quasi-geostrophic and reduced-gravity shallow ocean whose field is truncated to four dominant modes able to reproduce the large scale oceanic gyres (Pierini in J Phys Oceanogr 41:1585-1604, 2011). The two models are coupled through mechanical forcings only. The analysis of its dynamics reveals first that under aperiodic atmospheric forcings only dominant single gyres (clockwise or counterclockwise) appear, while for periodic atmospheric solutions the double gyres emerge. In the present model domain setting context, this feature is related to the level of truncation of the atmospheric fields, as indicated by a preliminary analysis of the impact of higher wavenumber ("synoptic" scale) modes on the development of oceanic gyres. In the latter case, double gyres appear in the presence of a chaotic atmosphere. Second the dynamical quantities characterizing the short-term predictability (Lyapunov exponents, Lyapunov dimension, Kolmogorov-Sinaï (KS) entropy) displays a complex dependence as a function of the key parameters of the system, namely the coupling strength and the external thermal forcing. In particular, the KS-entropy is increasing as a function of the coupling in most of the experiments, implying an increase of the rate of loss of information about the localization of the system on its attractor. Finally the dynamics of the error is explored and indicates, in particular, a rich variety of short term behaviors of the error in the atmosphere depending on the (relative) amplitude of the initial error affecting the ocean, from polynomial ( at 2 + bt 3 + ct 4) up to exponential-like evolutions. These features are explained

  2. MEP and planetary climates: insights from a two-box climate model containing atmospheric dynamics.

    PubMed

    Jupp, Tim E; Cox, Peter M

    2010-05-12

    A two-box model for equator-to-pole planetary heat transport is extended to include simple atmospheric dynamics. The surface drag coefficient CD is treated as a free parameter and solutions are calculated analytically in terms of the dimensionless planetary parameters eta (atmospheric thickness), omega (rotation rate) and xi (advective capability). Solutions corresponding to maximum entropy production (MEP) are compared with solutions previously obtained from dynamically unconstrained two-box models. As long as the advective capability xi is sufficiently large, dynamically constrained MEP solutions are identical to dynamically unconstrained MEP solutions. Consequently, the addition of a dynamical constraint does not alter the previously obtained MEP results for Earth, Mars and Titan, and an analogous result is presented here for Venus. The rate of entropy production in an MEP state is shown to be independent of rotation rate if the advective capability xi is sufficiently large (as for the four examples in the solar system), or if the rotation rate omega is sufficiently small. The model indicates, however, that the dynamical constraint does influence the MEP state when xi is small, which might be the case for some extrasolar planets. Finally, results from the model developed here are compared with previous numerical simulations in which the effect of varying surface drag coefficient on entropy production was calculated.

  3. Carbon Cycle and Vegetation Dynamics in the GFDL-Princeton University Coupled Atmosphere-Biosphere Model

    NASA Astrophysics Data System (ADS)

    Shevliakova, E.; Pacala, S. W.; Malyshev, S.; Hurtt, G. C.; Caspersen, J. P.

    2003-12-01

    Modeling global interactions between the atmosphere, hydrosphere and biosphere continues to pose a significant challenge, because of the tight and complex coupling of flows of water, energy, greenhouse gases, and ecosystem dynamics. We developed a comprehensive dynamic land surface model (LM3) able to simulate carbon and vegetation dynamics on time scales from minutes to centuries, as well as the exchange of water and energy among the land, LM3 predicts carbon dynamics in vegetation and soil in response to environmental conditions (weather, climate and soil type), ambient concentration of CO2, natural disturbances (e.g. fire), and anthropogenic land use changes (e.g. deforestation, agricultural cropland abandonment and forest management). A suite of the historical 300 years land cover change scenarios (developed at University of New Hampshire) is used to represent direct anthropogenic forcing on the terrestrial carbon system. Here we analyze the behavior of LM3 forced with observed atmospheric data and coupled with GFDL atmospheric circulation model AM2. The series of experiments indicates that our model adequately simulates climatic gradients of net primary productivity (NPP), leaf area index (LAI), biomass accumulation, evapotranspiration, and runoff. Additionally, analysis of the simulations suggests that anthropogenic land use has been a major forcing on the terrestrial carbon cycle, with large sources of CO2 caused primarily by deforestation and timber harvesting in the current tropics and past north temperate zone, and large current north temperate sinks caused primarily by secondary forest growth.

  4. Study of the diurnal variability of atmospheric chemistry with respect to boundary layer dynamics during DOMINO

    NASA Astrophysics Data System (ADS)

    van Stratum, B. J. H.; Vilà-Guerau de Arellano, J.; Ouwersloot, H. G.; van den Dries, K.; van Laar, T. W.; Martinez, M.; Lelieveld, J.; Diesch, J.-M.; Drewnick, F.; Fischer, H.; Hosaynali Beygi, Z.; Harder, H.; Regelin, E.; Sinha, V.; Adame, J. A.; Sörgel, M.; Sander, R.; Bozem, H.; Song, W.; Williams, J.; Yassaa, N.

    2012-03-01

    We study the interactions between atmospheric boundary layer (ABL) dynamics and atmospheric chemistry using a mixed-layer model (MXLCH) coupled to chemical reaction schemes. Guided by both atmospheric and chemical measurements obtained during the DOMINO campaign (2008), numerical experiments are performed to study the role of ABL dynamics and the accuracy of chemical schemes with different complexity: MOZART-4 and a reduced mechanism of this chemical system. Both schemes produce satisfactory results, indicating that the reduced scheme is capable of reproducing the O3-NOx-VOC-HOx diurnal cycle during conditions characterised by a low NOx regime and small O3 tendencies (less than 1 ppb per hour). By focussing on the budget equations of chemical species in the mixed-layer model, we show that for species like O3, NO and NO2, the influence of entrainment and boundary layer growth is of the same order as chemical production/loss. This indicates that an accurate representation of ABL processes is crucial in understanding the daily cycle of chemical species. By comparing the time scales of chemical reactive species with the mixing time scale of turbulence, we propose a classification based on the Damköhler number to further determine the importance of dynamics on chemistry during field campaigns. Our findings advocate an integrated approach, simultaneously solving the ABL dynamics and chemical reactions, in order to obtain a better understanding of chemical pathways and processes and the interpretation of the results obtained during measurement campaigns.

  5. Noble gas isotopic composition as a key reference parameter in a planetary atmospheric evolution model

    NASA Astrophysics Data System (ADS)

    Ozima, M.

    2010-12-01

    The isotopic composition of noble gases is a key reference parameter in discussing the evolution of planetary atmospheres. Currently, two widely occurring noble gas components are identified in the early solar system, one is the Solar Wind noble gas (SW-noble gas, hereafter) and another is the Q-noble gas in unaltered meteorites: both noble gases are characterized by their ubiquitous occurrence and high isotopic homogeneity. Since the SW-noble gas is directly ejected from the Sun, it has been assumed to be a good proxy of the average noble gas isotopic composition in the Sun, namely the solar noble gas. The systematic enrichment of the heavier isotopes in the Q-noble gas relative to the SW-noble gas is then commonly attributed to its isotopic fractionation from the SW-noble gas. However, the isotopic compositions of the SW-noble gas either implanted on lunar soils or trapped by artificial targets show considerable isotopic variation depending on the velocity of the Solar Wind. Therefore, it is important to examine how closely the SW-noble gas represents the indigenous solar noble gas component or the mean isotopic composition of noble gases of the Sun. Here we show that the isotopic composition of the SW-noble gas is substantially fractionated relative to the solar value, and therefore should not be used as a reference parameter. We further suggest that the post D-burning Q-noble gas (see below) is the better proxy of the solar noble gas, and this should be used as a reference of the Solar noble gas isotopic composition in discussing the planetary atmospheric evolution. The most distinct difference between the Q- and the SW-noble gas is apparent in a 3He/4He isotopic ratio: 4.64e-4 in Q-He [1], but 1.23e-4 in SW-He[2]. The difference is attributed to the conversion of deuteron (D) to 3He in the Sun, namely the D-burning [3], due to high temperature during the pre-main sequence stage of the Sun. With the use of recent data on D/H ratios from helio-seismology [4] and

  6. Dynamics Explorer 1: Energetic Ion Composition Spectrometer (EICS)

    NASA Technical Reports Server (NTRS)

    Shelley, E. G.; Peterson, W. K.; Collin, H. L.

    1994-01-01

    The Energetic Ion Composition Spectrometer (EICS) experiment was selected as part of the Dynamics Explorer (DE) Program. One of the primary goals of the DE program was to investigate in detail the plasma physics processes responsible for energizing thermal (approximately 1 eV) ionospheric ions and transporting them to the earth's plasma sheet and distant polar cap. The results of the EICS data analysis (including support of other investigators) and of the archiving efforts supported by this contract are summarized in this document. Also reported are some aspects of our operational support activities.

  7. Ensemble Simulations with Coupled Atmospheric Dynamic and Dispersion Models: Illustrating Uncertainties in Dosage Simulations.

    NASA Astrophysics Data System (ADS)

    Warner, Thomas T.; Sheu, Rong-Shyang; Bowers, James F.; Sykes, R. Ian; Dodd, Gregory C.; Henn, Douglas S.

    2002-05-01

    Ensemble simulations made using a coupled atmospheric dynamic model and a probabilistic Lagrangian puff dispersion model were employed in a forensic analysis of the transport and dispersion of a toxic gas that may have been released near Al Muthanna, Iraq, during the Gulf War. The ensemble study had two objectives, the first of which was to determine the sensitivity of the calculated dosage fields to the choices that must be made about the configuration of the atmospheric dynamic model. In this test, various choices were used for model physics representations and for the large-scale analyses that were used to construct the model initial and boundary conditions. The second study objective was to examine the dispersion model's ability to use ensemble inputs to predict dosage probability distributions. Here, the dispersion model was used with the ensemble mean fields from the individual atmospheric dynamic model runs, including the variability in the individual wind fields, to generate dosage probabilities. These are compared with the explicit dosage probabilities derived from the individual runs of the coupled modeling system. The results demonstrate that the specific choices made about the dynamic-model configuration and the large-scale analyses can have a large impact on the simulated dosages. For example, the area near the source that is exposed to a selected dosage threshold varies by up to a factor of 4 among members of the ensemble. The agreement between the explicit and ensemble dosage probabilities is relatively good for both low and high dosage levels. Although only one ensemble was considered in this study, the encouraging results suggest that a probabilistic dispersion model may be of value in quantifying the effects of uncertainties in a dynamic-model ensemble on dispersion model predictions of atmospheric transport and dispersion.

  8. Composition and decomposition of soybean and sorghum tissues grown under elevated atmospheric carbon dioxide

    SciTech Connect

    Henning, F.P.; Wood, C.W.; Rogers, H.H.; Runion, G.B.; Prior, S.A.

    1996-07-01

    It has been hypothesized that changes in both quantity and quality of plant residue inputs to soils as atmospheric carbon dioxide (CO{sub 2}) concentration increases may alter carbon (C) and nitrogen (N) turnover rates and pool sizes. We determined the effect of elevated atmospheric CO{sub 2} on plant tissue quality, and how modifications in tissue quality affect C and N mineralization. Soybean and sorghum were grown under elevated (704.96 {plus_minus} 0.33 {mu}mol CO{sub 2} mol{sup {minus}1}) and ambient (357.44 {plus_minus} 0.12 {mu}mol CO{sub 2} mol{sup {minus}1}) atmospheric CO{sub 2} in open-top chambers. Leaf and stem tissues were separated form harvested plants and analyzed for C,N, lignin, and cellulose. Tissues were applied to Norfolk loamy sand (fine-loamy, siliceous, thermic Typic Kandiudult) and aerobically incubated for 70-d to determine C and N mineralization, C turnover, relative N mineralization, and C/N mineralized. Elevated CO{sub 2} had no effect on plant residue C concentration, but N concentration of soybean leaves and stems and sorghum stems was reduced; however, CO{sub 2} enrichment increased C/N ratio and lignin concentration for only sorghum stems and soybean leaves, respectively. Source of plant residue (i.e., produced under either elevated or ambient CO{sub 2}) had no impact on soil C turnover, relative N mineralization, cumulative C and N mineralization, and C/N mineralized. These data suggest that increasing atmospheric CO{sub 2} will have little effect on composition or decomposition of field crop residues. Thus, since CO{sub 2} enrichment results in increased photosynthetic C fixation, the possibility exists for increased soil C storage under field crops in an elevated CO{sub 2} world. 29 refs., 4 figs., 4 tabs.

  9. Solar Cycle Variability in Mean Thermospheric Composition and Temperature Induced by Atmospheric Tides

    NASA Astrophysics Data System (ADS)

    Jones, M., Jr.; Forbes, J. M.; Hagan, M. E.

    2015-12-01

    Vertically-propagating atmospheric thermal tides whose origins lie in Earth's lower atmosphere are now widely recognized as one of the dominant "meteorological" drivers of space weather. Many prior research efforts have focused on documenting and understanding the role that dissipating tides play in determining the longitudinal and seasonal variability associated with lower thermospheric winds, temperature, and constituent densities. However, considerably less attention has focused on understanding the potential solar cycle variability in the mean thermospheric state induced by the tides. In this paper we utilize the National Center for Atmospheric Research Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM), forced with observationally-based tides at the model lower boundary from the Climatological Tidal Model of the Thermosphere (CTMT, from Oberheide et al. [2011]), to elucidate how the dissipating tides induce variations of up to 30 K in the zonal-mean thermosphere temperature between solar minimum and maximum. Numerical experiments are performed for the month of September and for solar minimum, medium, and maximum conditions in order to quantify the solar cycle variability associated with the different terms in the thermodynamic energy, major and minor neutral constituent continuity equations. Our analysis indicates that solar cycle variability in neutral temperatures results from a combination of net eddy heat transport effects and tidal modulation of net nitric oxide (NO) cooling. The chemical and dynamical pathways through which dissipating tides affect mean NO cooling differently at solar minimum and maximum are diagnosed.

  10. Particle sizes and composition of Mars atmospheric dust based upon Viking and Mariner 9 observations

    NASA Technical Reports Server (NTRS)

    Clancy, R. T.; Lee, S. W.; Gladstone, G. R.

    1993-01-01

    Mars atmospheric dust can play an important role in the thermal structure of the Mars atmosphere during periods of high dust loading. However, the radiative properties of Mars atmospheric dust remain uncertain due to uncertain definitions of the dust composition and size distribution. The analysis by Toon et al., of Mariner 9 IRIS spectra during the 1971-1972 global dust storm indicated a reasonable match between the modeled 9-micron absorption of montmorillinite and the observed 9-micron absorption. Toon et al. also determined that an effective (cross-section weighted) mean radius of 2.5 microns (R(sub mode) = 0.4 microns) provided a consistent fit of montmorillinite to the IRIS dust spectra at 9 microns. Pollack et al. analyzed Viking lander observations of atmospheric extinction and scattering at visible-near IR wavelengths (0.5-1.0 microns), and obtained consistency with the Toon et al. dust size distribution when the effects of nonspherical particle shapes were included. An additional, minor (1 percent) component of visible-ultraviolet absorbing material was required to model the derived visible (0.86) and ultraviolet (0.4-0.6) single-scattering albedos of the dust, since montmorillinite does not absorb sufficiently in this wavelength region. A combined analysis of the Viking IRTM and Mariner 9 observations was conducted to reassess the model of Mars atmospheric ultraviolet-to-infrared measurements of dust absorption and scattering. The optical constants for palagonite are incorporated in a doubling-adding radiative transfer model of the Mars atmosphere to simulate Mariner 9 IRIS spectra as well as the Viking IRTM IR band observations. Visible and ultraviolet single-scattering albedos based on the Hansen and Travis Mie scattering code were also derived. A tentative conclusion is that smaller dust particles (R(sub mode) = 0.15 microns, cross-section weighted mean R = 1.2 microns) composed of palagonite provide a much improved fit to the Mariner 9 IRIS spectra

  11. Unraveling the Dynamics of Aminopolymer/Silica Composites

    DOE PAGES

    Carrillo, Jan-Michael Y.; Sakwa-Novak, Miles A.; Holewinski, Adam; ...

    2016-02-25

    Branched poly(ethylenimine) (PEI) encapsulated within mesoporous silica (SBA-15), has proven to be an eective sorbent for developing carbon capture technologies. However, the structure-property correlations which govern their adsorptive properties is not well understood. By combining coarse-grained molecular dynamics simulations and neutron scattering experiments we are able to construct, and validate, a detailed model of the dynamics and morphology of the conned polymer within the mesoporous support. By varying the simulation properties we are able to probe, for the rst time, the direct relationship between the structure of the polymer and the non-monotonic dynamics of the polymer as a function ofmore » monomer concentration within an adsorbing cylindrical pore. Overall the simulation results are in good agreement with quasi-elastic neutron scattering (QENS) studies, suggesting an approach that can be a useful guide for understanding how to tune porous polymer composites for enhancing desired dynamical and structural behavior targeting enhanced carbon dioxide adsorption.« less

  12. Dynamic fiber debonding and push-out in model composites

    NASA Astrophysics Data System (ADS)

    Bi, Xiaopeng

    2003-10-01

    When a crack propagates in a fiber-reinforced composite material, a substantial part of energy is dissipated in the debonding and sliding of the bridging fibers located behind the advancing crack front. Because of the important effect they have on the fracture toughness of a composite, these processes have been the subject of extensive experimental, analytical and numerical work. However, the vast majority of existing work on this topic has been limited to quasi-static loading situations. The few investigations performed on various composite systems involving higher loading rates seem to indicate that the fiber sliding process presents some unusual and sometimes contradictory rate-dependent characteristics. To enhance the current understanding of dynamic fiber debonding and push-out in model fiber-reinforced composites, a combined experimental and numerical investigation was carried out. A modified split Hopkinson pressure bar was used to perform high-rate fiber push-out experiments on an aluminum/epoxy model composite system. An axisymmetric cohesive/volumetric finite element scheme was developed to simulate the push-out process. Effects of several important parameters such as interfacial strength, interfacial fracture toughness and fiber/matrix friction coefficient were investigated. Interface cohesive properties were extracted by comparison between experimental and numerical results. The comparison between numerics and experiments was made as close as possible by (a) simulating the entire experimental apparatus; (b) using loading directly measured in the experiments as input to the finite element analysis (FEA) code; (c) using measured material properties in the FEA simulations; and (d) accounting for effects such as large deformations, residual stresses (through a quasi-static pre-loading scheme), spontaneous crack formation (through a cohesive failure formulation) and dynamic frictional sliding. Details of the physical process were discussed by numerically

  13. Dynamic viscoelasticities for short fiber-thermoplastic elastomer composites

    SciTech Connect

    Guo, Wuyun; Ashida, Michio . Graduate School of Science and Technology)

    1993-11-20

    Dynamic moduli, E[prime] and E[double prime], and loss tangent tan [delta] were investigated for thermoplastic elastomers (TPEs), styrene-isoprene-styrene copolymers (SISs), styrene-butadiene-styrene copolymer (SBS), and Hytrel and composites reinforced by poly(ethylene terephthalate) (PET) short fibers. The styrenic TPEs have a typical rubbery behavior and the Hytrel TPE has medial characteristics between rubber and plastic. Both E[prime] and E[double prime] of the composites depended on the matrix as well as the fiber loading and fiber length. Based on the viewpoint of different extensibility between the fiber and the matrix elastomer, a triblock model was considered for estimating the storage modulus of the short fiber-TPE composites as follows: E[sub c] = [alpha] V[sub f]E[sub f] + [beta](1 [minus] V[sub f])E[sub m], where [alpha] and [beta] are the effective deformation coefficients for the fiber and the matrix elastomer, respectively. They can be quantitatively represented by modulus ratio M (= E[sub m]/E[sub f]) and fiber length L: [alpha] = (L[sup n] + k)M/(L[sup n]M + k), [beta] = (1 [minus] [alpha]V[sub f])/(1 [minus] V[sub f]), where the constants n and k are obtained experimentally. When k = 0.0222 and n = 0.45, E[sub c] of the TPE composites agreed well with the prediction of the proposed model. The relaxation spectrum of the composites showed a distinct main peak ascribed to the matrix elastomer, but no peak to the PET fiber.

  14. Characterization of Atmospheric Nitrate Dynamics in a Sub-Alpine Watershed Using Δ17O and δ15N

    NASA Astrophysics Data System (ADS)

    Bourgeois, I.; Savarino, J. P.; Clement, J. C.

    2015-12-01

    Remote subalpine ecosystems are usually characterized by nutrient-poor soils (Körner, 2004; Seastedt et al., 2004), making them particularly susceptible to undergo changes due to increased atmospheric N deposition (Vitousek et al., 1997; Preunkert et al., 2003). Using Δ17O, a conserved tracer of atmospheric nitrate (NO3 atm) (Michalski et al., 2004; Tsunogai et al., 2010), and δ15N, indicator of NO3 biological sources (Kendall, 1998; Casciotti et al., 2009), we measured the seasonal variations of NO3 atm stable isotopic composition and concentration in several streams and soils originating from two sub-alpine watersheds in the French Alps. Our objective was to investigate whether or not NO3 atm impacts the soil N biogeochemical cycle by increasing nutrients availability for plants and bacteria. We coupled streams and soils measurements with snow-pits sampling and aerosols collection at the Lautaret Pass, to better emphasize the correlation between atmospheric deposition, soil retention and watersheds effluents response. Our results reveal that different temporal dynamics govern our study site: stream measurements show that in spring, snowmelt results in a NO3 atm impulse, accounting for ca. 31 % of the total stream NO3 budget; on the opposite in autumn, NO3 atm accounts only for ca. 3 % of the total stream NO3 budget, highlighting the presence of a NO3 bacterial pool (nitrification). We also inferred from the observed Δ17O variations two distinct phenomena in the spring/summer season: a fast snow run-off and a slower snow-water percolation. The later is believed to affect most the soil N cycle as it directly increases available NO3. Measured soil leachates and extracts confirm this hypothesis and point out the potential importance of anthropogenic N deposition as on average 7 to 10 % of the soil solutions NO3 derives directly from the atmosphere.

  15. Experimental Studies of the Distribution of Minor Constituents and Dynamic Processes in the Atmosphere

    NASA Technical Reports Server (NTRS)

    Goodman, Jindra

    1999-01-01

    Minor constituents play an important role in atmospheric chemistry and serve as tracers in transport and mixing studies in tropospheric-stratospheric exchange processes. Measurements of trace gases are essential to an understanding of the mechanisms by which minor constituents originating in the troposphere, both naturally occurring and anthropogenic, reach the stratosphere. Many of these gases are sources of species directly involved in the chemistry of ozone depletion in the stratosphere and ozone generation in the troposphere. Some contribute to the warming of the atmosphere. Data on tracer distributions are important in the development of models for predicting photochemical effects in the stratosphere and troposphere. Data on atmospheric dynamics are important for the development of models for predicting the transport of photochemical species and for characterizing the nature of stratospheric motions.

  16. A Petascale Non-Hydrostatic Atmospheric Dynamical Core in the HOMME Framework

    SciTech Connect

    Tufo, Henry

    2015-09-15

    The High-Order Method Modeling Environment (HOMME) is a framework for building scalable, conserva- tive atmospheric models for climate simulation and general atmospheric-modeling applications. Its spatial discretizations are based on Spectral-Element (SE) and Discontinuous Galerkin (DG) methods. These are local methods employing high-order accurate spectral basis-functions that have been shown to perform well on massively parallel supercomputers at any resolution and scale particularly well at high resolutions. HOMME provides the framework upon which the CAM-SE community atmosphere model dynamical-core is constructed. In its current incarnation, CAM-SE employs the hydrostatic primitive-equations (PE) of motion, which limits its resolution to simulations coarser than 0.1 per grid cell. The primary objective of this project is to remove this resolution limitation by providing HOMME with the capabilities needed to build nonhydrostatic models that solve the compressible Euler/Navier-Stokes equations.

  17. Dynamical Models of Mira Atmospheres: Shocks, Limb Functions, and MG II Emission

    NASA Astrophysics Data System (ADS)

    Beach, Thomas Eugene

    1990-01-01

    Dynamic atmosphere models of Mira-type stars, prepared using a code developed by G. H. Bowen, were analyzed to determine observational implications of the models and suggest improvements to the code and model parameters. Three specific areas were addressed: Shock morphology, limb functions, and Mg II emission. The long-period, fundamental-mode models used in this study exhibit an unexpected shock morphology. In addition to the "main" shock, which forms as the radially pulsating surface of the Mira moves outward and is observed to travel out through atmosphere, a "preliminary" shock structure forms as rebounding layers of the atmosphere fall back onto lower layers. The preliminary shock remains deep in the atmosphere until overrun by the outward-moving main shock. The energy dissipated by the preliminary shock usually exceeds that dissipated by the main shock, and has important effects on the light curve. The dynamic atmosphere models exhibit radial extension of the atmosphere and post-shock emission that alter the limb function (limb darkening/brightening) of the models. The effects on stellar angular diameters measured by lunar occultation technique are calculated. The results show that the usual procedure of fitting occultation observations assuming a uniform brightness disk and then correcting the resulting diameter for limb darkening can give erroneous results. The dynamic effects cause Miras to appear larger and cooler than they actually are. A post-shock relaxation zone code developed by J. N. Pierce was modified and interfaced with the Bowen code to follow the ionization state and cooling radiation emitted by Hydrogen, Helium, and 23 metals in the models. Mg II emission data were used to prepare a light curve that is compared with Mg II light curves observed with the IUE satellite. The relaxation models show that the periodic passage of shocks through the atmosphere results in much lower concentrations of molecular hydrogen and higher ionization fractions

  18. COLLABORATIVE RESEARCH: CONTINUOUS DYNAMIC GRID ADAPTATION IN A GLOBAL ATMOSPHERIC MODEL: APPLICATION AND REFINEMENT

    SciTech Connect

    Prusa, Joseph

    2012-05-08

    This project had goals of advancing the performance capabilities of the numerical general circulation model EULAG and using it to produce a fully operational atmospheric global climate model (AGCM) that can employ either static or dynamic grid stretching for targeted phenomena. The resulting AGCM combined EULAG's advanced dynamics core with the physics of the NCAR Community Atmospheric Model (CAM). Effort discussed below shows how we improved model performance and tested both EULAG and the coupled CAM-EULAG in several ways to demonstrate the grid stretching and ability to simulate very well a wide range of scales, that is, multi-scale capability. We leveraged our effort through interaction with an international EULAG community that has collectively developed new features and applications of EULAG, which we exploited for our own work summarized here. Overall, the work contributed to over 40 peer- reviewed publications and over 70 conference/workshop/seminar presentations, many of them invited.

  19. Dynamic model constraints on oxygen-17 depletion in atmospheric O2 after a snowball Earth.

    PubMed

    Cao, Xiaobin; Bao, Huiming

    2013-09-03

    A large perturbation in atmospheric CO2 and O2 or bioproductivity will result in a drastic pulse of (17)O change in atmospheric O2, as seen in the Marinoan Oxygen-17 Depletion (MOSD) event in the immediate aftermath of a global deglaciation 635 Mya. The exact nature of the perturbation, however, is debated. Here we constructed a coupled, four-box, and quick-response biosphere-atmosphere model to examine both the steady state and dynamics of the MOSD event. Our model shows that the ultra-high CO2 concentrations proposed by the "snowball' Earth hypothesis produce a typical MOSD duration of less than 10(6) y and a magnitude of (17)O depletion reaching approximately -35‰. Both numbers are in remarkable agreement with geological constraints from South China and Svalbard. Moderate CO2 and low O2 concentration (e.g., 3,200 parts per million by volume and 0.01 bar, respectively) could produce distinct sulfate (17)O depletion only if postglacial marine bioproductivity was impossibly low. Our dynamic model also suggests that a snowball in which the ocean is isolated from the atmosphere by a continuous ice cover may be distinguished from one in which cracks in the ice permit ocean-atmosphere exchange only if partial pressure of atmospheric O2 is larger than 0.02 bar during the snowball period and records of weathering-derived sulfate are available for the very first few tens of thousands of years after the onset of the meltdown. In any case, a snowball Earth is a precondition for the observed MOSD event.

  20. Dynamic model constraints on oxygen-17 depletion in atmospheric O2 after a snowball Earth

    PubMed Central

    Cao, Xiaobin; Bao, Huiming

    2013-01-01

    A large perturbation in atmospheric CO2 and O2 or bioproductivity will result in a drastic pulse of 17O change in atmospheric O2, as seen in the Marinoan Oxygen-17 Depletion (MOSD) event in the immediate aftermath of a global deglaciation 635 Mya. The exact nature of the perturbation, however, is debated. Here we constructed a coupled, four-box, and quick-response biosphere–atmosphere model to examine both the steady state and dynamics of the MOSD event. Our model shows that the ultra-high CO2 concentrations proposed by the “snowball’ Earth hypothesis produce a typical MOSD duration of less than 106 y and a magnitude of 17O depletion reaching approximately −35‰. Both numbers are in remarkable agreement with geological constraints from South China and Svalbard. Moderate CO2 and low O2 concentration (e.g., 3,200 parts per million by volume and 0.01 bar, respectively) could produce distinct sulfate 17O depletion only if postglacial marine bioproductivity was impossibly low. Our dynamic model also suggests that a snowball in which the ocean is isolated from the atmosphere by a continuous ice cover may be distinguished from one in which cracks in the ice permit ocean–atmosphere exchange only if partial pressure of atmospheric O2 is larger than 0.02 bar during the snowball period and records of weathering-derived sulfate are available for the very first few tens of thousands of years after the onset of the meltdown. In any case, a snowball Earth is a precondition for the observed MOSD event. PMID:23898167

  1. Dynamic thermo-mechanical properties of various flowable resin composites

    PubMed Central

    Balthazard, Rémy; Vincent, Marin; Dahoun, Abdessellam; Mortier, Eric

    2016-01-01

    Background This study compared the storage modulus (E’), the loss modulus (E’’) and the loss tangent (tan δ) of various flowable resin composites. Material and Methods Grandio Flow (GRF), GrandioSo Heavy Flow (GHF), Filtek Supreme XTE (XTE) and Filtek Bulk Fill (BUL) flowable resins and Clinpro Sealant (CLI) ultra-flowable pit and fissure sealant resin were used. 25 samples were tested using a dynamical mechanical thermal analysis system in bending mode. Measurements were taken within a temperature range of 10 to 55°C. The results were statistically analyzed using mixed-effect and repeated-measure analysis of variance followed by paired multiple comparisons. Results For all the materials, the E’ values decrease with temperature, whereas the tan δ values increase. Irrespective of the temperature, GHF and GRF present E’ and E’’ values significantly higher than all the other materials and CLI presents values significantly lower than all the other materials. Observation of the values for all the materials reveals a linear progression of the tan δ values with temperature. Conclusions A variation in temperature within a physiological range generates modifications in mechanical properties without damaging the material, however. Filler content in volume terms appears to be the crucial parameter in the mechanical behavior of tested materials. Key words:Dynamic mechanical thermal analysis, elastic modulus, filler content, flowable resin composites, loss modulus, loss tangent. PMID:27957266

  2. Chemical Composition of Atmospheric Aerosols Above a Pristine South East Asian Rainforest

    NASA Astrophysics Data System (ADS)

    Robinson, N. H.; Allan, J. D.; Williams, P. I.; Coe, H.; Hamilton, J.; Chen, Q.; Martin, S.; Trembath, J.

    2009-04-01

    The tropics emit a huge amount of volatile organic compounds (VOCs) into the Earth's atmosphere. The processes by which these gases are oxidised to form secondary organic aerosol (SOA) are currently not well understood or quantified. Intensive field measurements were carried out as part of the Oxidant and Particle Photochemical Processes (OP3) and the Aerosol Coupling in the Earth System (ACES) projects around pristine rainforest in Malaysian Borneo. This is the first campaign of its type in a South East Asian rainforest. We present detailed organic aerosol composition measurements made using an Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS) at Bukit Atur, a Global Atmosphere Watch site located in the Danum Valley Conservation Area. This is a state-of-the-art field deployable instrument that can provide real time composition, mass loading and aerodynamic particle sizing information. In addition, the mass spectral resolution is sufficient to perform an analysis of the elemental composition of the organic species present. Other tools such as positive matrix factorisation (PMF) have been used to help assess the relative source contributions to the organic aerosol. A suite of supporting aerosol and gas phase measurements were made, including size resolved number concentration measurements with Differential Mobility Particle Sizer (DMPS), as well as absorption measurements made with a Multi-Angle Absorption Photometer (MAAP). The ground site data are compared with Aerodyne Compact Time of Flight Aerosol Mass Spectrometer (C-ToF-AMS) measurements made on the UK Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 research aircraft. Airborne measurements were made above pristine rainforest surrounding the Danum Valley site, as well as nearby oil palm agricultural sites and palm oil rendering plants. Airborne hygroscopicity was measured using a Droplet Measurement Technology Cloud Condensation Nuclei counter (DMT CCN counter) in

  3. Dynamic Mesh CFD Simulations of Orion Parachute Pendulum Motion During Atmospheric Entry

    NASA Technical Reports Server (NTRS)

    Halstrom, Logan D.; Schwing, Alan M.; Robinson, Stephen K.

    2016-01-01

    This paper demonstrates the usage of computational fluid dynamics to study the effects of pendulum motion dynamics of the NASAs Orion Multi-Purpose Crew Vehicle parachute system on the stability of the vehicles atmospheric entry and decent. Significant computational fluid dynamics testing has already been performed at NASAs Johnson Space Center, but this study sought to investigate the effect of bulk motion of the parachute, such as pitching, on the induced aerodynamic forces. Simulations were performed with a moving grid geometry oscillating according to the parameters observed in flight tests. As with the previous simulations, OVERFLOW computational fluid dynamics tool is used with the assumption of rigid, non-permeable geometry. Comparison to parachute wind tunnel tests is included for a preliminary validation of the dynamic mesh model. Results show qualitative differences in the flow fields of the static and dynamic simulations and quantitative differences in the induced aerodynamic forces, suggesting that dynamic mesh modeling of the parachute pendulum motion may uncover additional dynamic effects.

  4. Middle Atmosphere Temperature and Dynamics as Revealed from D-region Observations

    NASA Technical Reports Server (NTRS)

    Danilov, A. D.

    1984-01-01

    The concept of so-called meteorological control of the ionospheric D-region is presently undergoing development. According to this concept the electron concentration in this region is governed not only by solar and geomagnetic parameters but strongly depends on the temperature and dynamical regime of the mesosphere and stratosphere. How this connection between D-region and meteorological parameters can be used to obtain some information about middle atmosphere temperature and dynamics is examined. The essential points of the meteorological control concept are reviewed and the influence of turbulence on nitric oxide distribution and thus the ion production rate is discussed.

  5. Human population and atmospheric carbon dioxide growth dynamics: Diagnostics for the future

    NASA Astrophysics Data System (ADS)

    Hüsler, A. D.; Sornette, D.

    2014-10-01

    We analyze the growth rates of human population and of atmospheric carbon dioxide by comparing the relative merits of two benchmark models, the exponential law and the finite-time-singular (FTS) power law. The later results from positive feedbacks, either direct or mediated by other dynamical variables, as shown in our presentation of a simple endogenous macroeconomic dynamical growth model describing the growth dynamics of coupled processes involving human population (labor in economic terms), capital and technology (proxies by CO2 emissions). Human population in the context of our energy intensive economies constitutes arguably the most important underlying driving variable of the content of carbon dioxide in the atmosphere. Using some of the best databases available, we perform empirical analyses confirming that the human population on Earth has been growing super-exponentially until the mid-1960s, followed by a decelerated sub-exponential growth, with a tendency to plateau at just an exponential growth in the last decade with an average growth rate of 1.0% per year. In contrast, we find that the content of carbon dioxide in the atmosphere has continued to accelerate super-exponentially until 1990, with a transition to a progressive deceleration since then, with an average growth rate of approximately 2% per year in the last decade. To go back to CO2 atmosphere contents equal to or smaller than the level of 1990 as has been the broadly advertised goals of international treaties since 1990 requires herculean changes: from a dynamical point of view, the approximately exponential growth must not only turn to negative acceleration but also negative velocity to reverse the trend.

  6. A method for the analysis of nonlinearities in aircraft dynamic response to atmospheric turbulence

    NASA Technical Reports Server (NTRS)

    Sidwell, K.

    1976-01-01

    An analytical method is developed which combines the equivalent linearization technique for the analysis of the response of nonlinear dynamic systems with the amplitude modulated random process (Press model) for atmospheric turbulence. The method is initially applied to a bilinear spring system. The analysis of the response shows good agreement with exact results obtained by the Fokker-Planck equation. The method is then applied to an example of control-surface displacement limiting in an aircraft with a pitch-hold autopilot.

  7. Modulating Exciton Dynamics in Composite Nanocrystals for Excitonic Solar Cells.

    PubMed

    Concina, Isabella; Manzoni, Cristian; Grancini, Giulia; Celikin, Mert; Soudi, Afsoon; Rosei, Federico; Zavelani-Rossi, Margherita; Cerullo, Giulio; Vomiero, Alberto

    2015-07-02

    Quantum dots (QDs) represent one of the most promising materials for third-generation solar cells due to their potential to boost the photoconversion efficiency beyond the Shockley-Queisser limit. Composite nanocrystals can challenge the current scenario by combining broad spectral response and tailored energy levels to favor charge extraction and reduce energy and charge recombination. We synthesized PbS/CdS QDs with different compositions at the surface of TiO2 nanoparticles assembled in a mesoporous film. The ultrafast photoinduced dynamics and the charge injection processes were investigated by pump-probe spectroscopy. We demonstrated good injection of photogenerated electrons from QDs to TiO2 in the PbS/CdS blend and used the QDs to fabricate solar cells. The fine-tuning of chemical composition and size of lead and cadmium chalcogenide QDs led to highly efficient PV devices (3% maximum photoconversion efficiency). This combined study paves the way to the full exploitation of QDs in next-generation photovoltaic (PV) devices.

  8. Comparison of Dynamic Characteristics for an Inflatable Solar Concentrator in Atmospheric and Thermal Vacuum Conditions

    NASA Technical Reports Server (NTRS)

    Slade, Kara N.; Tinker, Michael L.; Lassiter, John O.; Engberg, Robert

    2000-01-01

    Dynamic testing of an inflatable solar concentrator structure in a thermal vacuum chamber as well as in ambient laboratory conditions is described in detail. Unique aspects of modal testing for the extremely lightweight inflatable are identified, including the use of a noncontacting laser vibrometer measurement system. For the thermal vacuum environment, mode shapes and frequency response functions are compared for three different test article inflation pressures at room temperature. Modes that persist through all the inflation pressure regimes are identified, as well as modes that are unique for each pressure. In atmospheric pressure and room temperature conditions, dynamic measurements were obtained for the expected operational inflation pressure of 0.5 psig. Experimental mode shapes and frequency response functions for ambient conditions are described and compared to the 0.5 psig results from the thermal vacuum tests. Only a few mode shapes were identified that occurred in both vacuum and atmospheric environments. This somewhat surprising result is discussed in detail, and attributed at least partly to 1.) large differences in modal damping, and 2.) significant differences in the mass of air contained by the structure, in the two environments. Results of this investigation point out the necessity of testing inflatable space structures in vacuum conditions before they can be launched. Ground testing in atmospheric pressure is not sufficient for predicting on-orbit dynamics of non-rigidized inflatable systems.

  9. An Evaluation of Using Dynamical Downscaling to Reconstruct Historical Atmospheric Data

    NASA Astrophysics Data System (ADS)

    Mann, Hilary M.

    The purpose of this project is to determine whether climate data reconstruction by dynamical downscaling of NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research) historical global reanalysis atmospheric data can provide an accurate input for hydrological models to be used in watersheds with limited ground observations. To do this, historical global reanalysis atmospheric data were dynamically downscaled to a 3km resolution over the Upper Feather, Yuba, and American River watersheds using the Fifth-Generation NCAR / Penn State Mesoscale Model (MM5). To validate the reconstructed precipitation, historical data from California Data Exchange Center (CDEC) stations were first used. However, the data that can be obtained from them are coarse throughout the watersheds, so historical data from PRISM (parameter-elevation regressions on independent slopes model) were also used. The observation data from CDEC stations were compared to the model-simulated (reconstructed) hourly, 72-hour, and monthly averaged precipitation data. These comparisons all had fairly accurate results, allowing the temporal accuracy of the model to be validated. PRISM observation data were used to compare the simulated monthly basin-average precipitation and its spatial distribution over each watershed. These comparisons showed very good results for timing and peak values. Consequently, it was determined that the current MM5 Mesoscale Model can produce the accurate precipitation field data by dynamical downscaling for use in practice.

  10. The role of atmospheric internal variability on the tropical instability wave dynamics

    NASA Astrophysics Data System (ADS)

    Narapusetty, Balachandrudu; Stan, Cristiana; Kirtman, Ben P.; Schopf, Paul S.; Marx, Lawrence; Kinter, James L., III

    2012-11-01

    The impact of atmospheric internal variability on tropical instability wave (TIW) activity in the eastern equatorial Pacific is examined. To diagnose the atmospheric internal variability, two simulations were performed with a state-of-the-art coupled general circulation model that uses an eddy permitting ocean component model. Standard coupling procedures are implemented in the control simulation. In the experimental simulation, the so-called interactive ensemble coupling is used, which systematically reduces the contribution of internal atmospheric dynamics to the air-sea fluxes of heat, momentum and fresh water. In the eastern equatorial Pacific, the reduction of the atmospheric internal variability leads to an enhancement of the available potential energy and higher exchanges from mean to eddy potential energy. The perturbations in the available potential energy and the eddy potential energy contribute to the enhancement in the TIW activity through the increased eddy kinetic energy. Due to the negative correlation between the atmospheric internal variability and TIW activity, the covariance between the momentum flux at the air-sea interface and the ocean surface currents as well as heat flux at the air-sea interface and the sea surface temperatures were nearly conserved west of 120°W between the control and the experimental simulations.

  11. Modeling Io's Sublimation-Driven Atmosphere: Gas Dynamics and Radiation Emission

    SciTech Connect

    Walker, Andrew C.; Goldstein, David B.; Varghese, Philip L.; Trafton, Laurence M.; Moore, Chris H.; Stewart, Benedicte; Gratiy, Sergey L.; Levin, Deborah A.

    2008-12-31

    Io's sublimation-driven atmosphere is modeled using the direct simulation Monte Carlo method. These rarefied gas dynamics simulations improve upon earlier models by using a three-dimensional domain encompassing the entire planet computed in parallel. The effects of plasma impact heating, planetary rotation, and inhomogeneous surface frost are investigated. Circumplanetary flow is predicted to develop from the warm subsolar region toward the colder night-side. The non-equilibrium thermal structure of the atmosphere, including vibrational and rotational temperatures, is also presented. Io's rotation leads to an asymmetric surface temperature distribution which is found to strengthen circumplanetary flow near the dusk terminator. Plasma heating is found to significantly inflate the atmosphere on both day- and night-sides. The plasma energy flux also causes high temperatures at high altitudes but permits relatively cooler temperatures at low altitudes near the dense subsolar point due to plasma energy depletion. To validate the atmospheric model, a radiative transfer model was developed utilizing the backward Monte Carlo method. The model allows the calculation of the atmospheric radiation from emitting/absorbing and scattering gas using an arbitrary scattering law and an arbitrary surface reflectivity. The model calculates the spectra in the {nu}{sub 2} vibrational band of SO{sub 2} which are then compared to the observational data.

  12. Morphology and Chemical composition of Atmospheric Particles over Semi-Arid region (Jaipur, Rajasthan) of India

    NASA Astrophysics Data System (ADS)

    Mishra, S. K.; Agnihotri, R.; Yadav, P.; Singh, S.; Tawale, J. S.; Rashmi, R.; Prasad, M.; Arya, B. C.; Mishra, N.

    2012-12-01

    Uncertainties associated with the radiative forcing of atmospheric dust particles is highest, owing to lack of region-specific dust morphology (particle shape, size) and mineralogy (chemical composition) database, needed for modeling their optical properties (Mishra and Tripathi, 2008). To fill this gap for the Indian region, we collected atmospheric particles (with aerodynamic size <5um, PM5 and a few bulk particles; TSP) from seven sites of Jaipur and nearby locales (semi-arid region, in the vicinity of Thar Desert of Rajasthan) at varying altitude, during late winters of ca. 2012. PM5 particles were collected on Teflon filters (for bulk chemical analyses), while pure Tin substrates (~1×1 mm2) were used for investigating individual particle morphology. Using Scanning Electron Microscope equipped with Energy Dispersive X ray (SEM-EDX) facility at NPL, images of individual particles were recorded and the morphological parameters (e.g. Aspect ratio; AR, Circulatory parameter; CIR.) were retrieved following Okada et al. (2001), whereas chemical compositions of individual particles were determined by EDX and bulk samples by X ray fluorescence (XRF). The geometrical size distributions of atmospheric particles were generated for each site. Based on NIST (National Institute of Standard and Technology, USA) morphology database, the site-specific individual particle shapes reveal predominance of "Layered" (calcite and quartz rich), "Angular" structures (quartz rich) and "Flattened" particles over all the sites. Particles were found to be highly non-spherical with irregular shapes (CIR varying from 1 to 0.22 with median value ~0.76; AR varying from 1 to 5.4 with median value ~1.64). Noteworthy to mention, that unit values of AR and CIR represent spherical particles. Chemical analyses of PM5 particles revealed dominance of crustal elements e.g. Si, Al, Fe, Ca, Mg, in general. Particles over Kukas Hill (27.027° N, 75.919° E; ~800 MAGL) showed highest Fe mass fractions (~43

  13. Improvement of Strength Characteristics of Aerospace Fiber Reinforced Composite Materials using Atmospheric Pressure Plasma-Graft Polymerization Treatment

    NASA Astrophysics Data System (ADS)

    Aoi, Tatsuji; Kuroki, Tomoyuki; Tahara, Mitsuru; Okubo, Masaaki

    The atmospheric pressure nonthermal plasma-graft polymerization treatment is applied for the surface modification of the organic fibers in order to enhance the strength of the aerospace structural composite material consisting of the laminated textiles. The influence of the treatment on the composite materials' strength properties is examined. As a result, the plasma-graft polymerization surface treatment is effective for the compression and bend of the composite materials. Because the interfacial bonding between each fiber and matrix resin is strengthened by the treatment, the strengths of the composite materials are increased.

  14. Water cycle dynamic increases resilience of vegetation under higher atmospheric carbon dioxide concentration

    NASA Astrophysics Data System (ADS)

    Lemordant, L. A.; Gentine, P.; Stéfanon, M.; Drobinski, P. J.; Fatichi, S.

    2015-12-01

    Plant stomata couple the energy, water and carbon cycles. Photosynthesis requires stomata to open to take up carbon dioxide. In the process water vapor is released as transpiration. As atmospheric CO2 concentration rises, for the same amount of CO2 uptake, less water vapor is transpired, translating into higher water use efficiency. Reduced water vapor losses will increase soil water storage if the leaf area coverage remains similar. This will in turn alter the surface energy partitioning: more heat will be dissipated as sensible heat flux, resulting in possibly higher surface temperatures. In contrast with this common hypothesis, our study shows that the water saved during the growing season by increased WUE can be mobilized by the vegetation and help reduce the maximum temperature of mid-latitude heat waves. The large scale meteorological conditions of 2003 are the basis of four regional model simulations coupling an atmospheric model to a surface model. We performed two simulations with respectively 2003 (CTL) and 2100 (FUT) atmospheric CO2 applied to both the atmospheric and surface models. A third (RAD) and a fourth (FER) simulations are run with 2100 CO2 concentration applied to respectively the atmospheric model only and the surface model only. RAD investigates the impact of the radiative forcing, and FER the response to vegetation CO2 fertilization. Our results show that the water saved through higher water use efficiency during the growing season enabled by higher atmospheric carbon dioxide concentrations helps the vegetation to cope during severe heat and dryness conditions in the summer of mid-latitude climate. These results demonstrate that consideration of the vegetation carbon cycle is essential to model the seasonal water cycle dynamic and land-atmosphere interactions, and enhance the accuracy of the model outputs especially for extreme events. They also have important implications for the future of agriculture, water resources management, ecosystems

  15. Satellite Observations of Arctic and Antarctic Polar Stratospheric Clouds and Atmospheric Composition

    NASA Astrophysics Data System (ADS)

    Lambert, A.; Santee, M. L.; Wu, D. L.

    2012-12-01

    We present an overview of polar stratospheric clouds (PSCs) and atmospheric composition during the 2008-2012 Arctic and Antarctic seasons using A-Train measurements of lidar backscatter and gas phase concentrations of HNO3, H2O, HCl and ClO. The processes of denitrification, dehydration and chlorine activation are investigated. PSC types are classified using the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite which measures vertical profiles of aerosol and cloud backscatter at 532 nm (total and perpendicular polarization) and 1064 nm. Ambient temperature/pressure profiles and constituent gases are obtained from the Aura Microwave Limb Sounder (MLS). Since April 2008 these two instruments have flown in close formation in the A-Train, maintaining colocation across track to less than 10 km and with temporal sampling differences less than 30 seconds.

  16. Improving adhesion of powder coating on PEEK composite: Influence of atmospheric plasma parameters

    NASA Astrophysics Data System (ADS)

    Dupuis, Aurélie; Ho, Thu Huong; Fahs, Ahmad; Lafabrier, Aurore; Louarn, Guy; Bacharouche, Jalal; Airoudj, Aissam; Aragon, Emmanuel; Chailan, Jean-François

    2015-12-01

    In aeronautic industries, powder coatings are increasingly used because of environmental considerations. During the deposition of such a coating on a substrate piece, the main objective is to obtain a good coating/substrate adhesion. In this study, the targeted substrate is a Poly-(Ether EtherKetone)-(PEEK) based composite material. Due to the poor surface energy of PEEK, a surface treatment is necessary in order to enhance its adhesion with the coating. In this purpose, atmospheric plasma treatment has been chosen and the influence of plasma parameters has been studied. Four scan speed nozzles and three gases (Air, N2 and Argon) plasma has been tested. The increase of adhesion with increasing wettability, polarity and nanoroughness has been evidenced. A particular study of the type of grafted polar functionalities according to gas nature allowed to better understand the plasma mechanism and the cross-impact of polarity and nanoroughness in adhesion enhancement.

  17. Surface Modification of PBO Fibers for Composites by Coaxial Atmospheric Dielectric Barrier Discharge (PLA-PLA)

    NASA Astrophysics Data System (ADS)

    Hu, Qianqian; Xu, Jinzhou; Zhou, Zhenxing; Zhang, Jing

    2013-05-01

    In this work, the surface modification of poly (1, 4-phenylene-cis-benzobisoxazole) (PBO) fibers by O2/Ar coaxial atmospheric dielectric barrier discharge was investigated, as well as the interfacial adhesion properties of modified PBO fibers/epoxy composites. The results indicated that the contact angle decreased remarkably from 84.7° to 63.5° after 3 min O2/Ar plasma treatment. SEM and AFM images showed that the surface of the treated PBO fibers became rather rough. In addition, XPS results suggested that the polar functional group (O=C—O) was introduced on the surface of the treated PBO fiber. The interfacial adhesion test showed that the interfacial shear strength (IFSS) and the interlaminar shear strength (ILSS) increased significantly by 63.54% and 130%, respectively. Moreover, the excellent tensile property of the PBO fibres was well preserved.

  18. The CEOS Atmospheric Composition Constellation: Enhancing the Value of Space-Based Observations

    NASA Technical Reports Server (NTRS)

    Eckman, Richard; Zehner, Claus; Al-Saadi, Jay

    2015-01-01

    The Committee on Earth Observation Satellites (CEOS) coordinates civil space-borne observations of the Earth. Participating agencies strive to enhance international coordination and data exchange and to optimize societal benefit. In recent years, CEOS has collaborated closely with the Group on Earth Observations (GEO) in implementing the Global Earth Observing System of Systems (GEOSS) space-based objectives. The goal of the CEOS Atmospheric Composition Constellation (ACC) is to collect and deliver data to improve monitoring, assessment and predictive capabilities for changes in the ozone layer, air quality and climate forcing associated with changes in the environment through coordination of existing and future international space assets. A project to coordinate and enhance the science value of a future constellation of geostationary sensors measuring parameters relevant to air quality supports the forthcoming European Sentinel-4, Korean GEMS, and US TEMPO missions. Recommendations have been developed for harmonization to mutually improve data quality and facilitate widespread use of the data products.

  19. An Overview of Atmospheric Composition OSSE Activities at NASA's Global Modeling and Assimilation Office

    NASA Technical Reports Server (NTRS)

    daSilva, Arlinda

    2012-01-01

    A model-based Observing System Simulation Experiment (OSSE) is a framework for numerical experimentation in which observables are simulated from fields generated by an earth system model, including a parameterized description of observational error characteristics. Simulated observations can be used for sampling studies, quantifying errors in analysis or retrieval algorithms, and ultimately being a planning tool for designing new observing missions. While this framework has traditionally been used to assess the impact of observations on numerical weather prediction, it has a much broader applicability, in particular to aerosols and chemical constituents. In this talk we will give a general overview of Observing System Simulation Experiments (OSSE) activities at NASA's Global Modeling and Assimilation Office, with focus on its emerging atmospheric composition component.

  20. Structure and composition of the neutral upper atmosphere of Mars from the MAVEN NGIMS investigation

    PubMed Central

    Benna, M.; Elrod, M.; Yelle, R. V.; Bougher, S. W.; Stone, S. W.; Jakosky, B. M.

    2015-01-01

    Abstract The Mars Atmosphere and Volatile EvolutioN (MAVEN) Neutral Gas and Ion Mass Spectrometer (NGIMS) provides sensitive detections of neutral gas and ambient ion composition. NGIMS measurements of nine atomic and molecular neutral species, and their variation with altitude, latitude, and solar zenith angle are reported over several months of operation of the MAVEN mission. Sampling NGIMS signals from multiple neutral species every several seconds reveals persistent and unexpectedly large amplitude density structures. The scale height temperatures are mapped over the course of the first few months of the mission from high down to midlatitudes. NGIMS measurements near the homopause of 40Ar/N2 ratios agree with those reported by the Sample Analysis at Mars investigation and allow the altitude of the homopause for the most abundant gases to be established. PMID:27667873

  1. A thirty year record of the isotopic composition of atmospheric methane from North America

    NASA Astrophysics Data System (ADS)

    Rice, A. L.; Teama, D. G.; Roeger, F. H.; Butenhoff, C. L.; Khalil, A. K.

    2012-12-01

    Methane (CH4) is one of the most important greenhouse gases after water vapor and carbon dioxide. Its atmospheric concentration increased from 650 ppb during the preindustrial era to nearly 1800 ppb in the present day due to human activities such as rice cultivation, animal husbandry, biomass burning, and fossil fuel production and use. Since the 1980s, the long-term growth rate of atmospheric CH4 slowed dramatically consistent with a leveling off of CH4 sources with significant interannual variability over this period. One powerful tool to constrain changes in sources and sinks is the use of stable isotopes of atmospheric CH4 because of the distinct values of carbon isotope (δ13C) and hydrogen isotope (δD) ratios in CH4 sources and characteristic isotopic fractionation effects in sinks. Measurements of the long-term trend of the isotopic composition of CH4 can improve the constraint of changes to the CH4 budget from microbial sources (e.g., wetlands, ruminants, and rice agriculture, δ13C ~-60 ‰, δD ~-300‰), fossil sources (e.g. natural gas and coal mining, δ13C ~-40‰, δD ~-200‰), and biomass burning (δ13C ~-25‰, δD ~-100‰). In this work, we present measurements of δ13C and δD of atmospheric CH4 from a unique archive of more than 200 air samples collected at Cape Meares, Oregon (45.5°N, 124°W) from 1978 to 1998. The measurements from this archive indicate enrichments in both isotope tracers over this period which average 0.017 (±0.002) ‰yr-1 for δ13C and 0.68 (±0.04) ‰yr-1 for δD. Seasonal cycles in δ13C and δD are also evident with amplitudes of ~ 0.3 ‰ and ~ 4 ‰, respectively; maximum values are found May-July and minimum values September-December, consistent with previous results from the mid-latitude northern hemisphere. Combining our results with more recent timeseries since 1988 from Olympic Peninsula (WA, 48°N), Montana de Oro (CA, 35°N), and Niwot Ridge (CO, 40°N) provides a composite record of the isotopic

  2. Dissipative Particle Dynamics modeling of nanorod-polymer composites

    NASA Astrophysics Data System (ADS)

    Khani, Shaghayegh; Maia, Joao

    2014-11-01

    Recent years have seen a plethora of experimental methods for fabricating nanorod-polymer composites with enhanced physical and mechanical properties. The macroscopic properties of the composites are directly related to the dispersion and organization of the nanoparticles in the matrix. For instance, a significant improvement in the properties of the nanorod-polymer composites is observed upon formation of a percolating network. Thus, controlling the structure of the nanoparticles in the matrix will advance the technology in the field. One way of doing this is by adjusting the chemical interactions which is done through grafting polymer chains on the surface of the rods. Although the enthalpic interactions play the major role in such systems other entropic variables such as the dimension of the rods, density of grafting and etc. may influence the final morphology of the system. The recent developments in the computational techniques have paved the road for further understanding of the controlled assembly of nanorods in polymer matrices. In this study, Dissipative Particle Dynamics (DPD) is employed in order to investigate the effect of enthalpic and entopic variables on the phase behavior of the nanorod-polymer composites. DPD is a coarse-grained mesoscale method which has been found very promising in simulating multi component systems. The interaction parameter between the components of the systems can be mapped onto the Flory-Huggins χ-parameter via well-known Groot-Warren expression. The main goal of this work is to provide a phase diagram that can be used to guide the experiments in designing new materials.

  3. Optical properties, morphology and elemental composition of atmospheric particles at T1 supersite on MILAGRO campaign

    NASA Astrophysics Data System (ADS)

    Carabali, G.; Mamani-Paco, R.; Castro, T.; Peralta, O.; Herrera, E.; Trujillo, B.

    2012-03-01

    Atmospheric particles were sampled at T1 supersite during MILAGRO campaign, in March 2006. T1 was located at the north of Mexico City (MC). Aerosol sampling was done by placing copper grids for Transmission Electron Microscope (TEM) on the last five of an 8-stage MOUDI cascade impactor. Samples were obtained at different periods to observe possible variations on morphology. Absorption and scattering coefficients, as well as particle concentrations (0.01-3 μm aerodynamic diameter) were measured simultaneously using a PSAP absorption photometer, a portable integrating nephelometer, and a CPC particle counter. Particle images were acquired at different magnifications using a CM 200 Phillips TEM-EDAX system, and then calculated the border-based fractal dimension. Also, Energy Dispersive X-Ray Spectroscopy (EDS) was used to determine the elemental composition of particles. The morphology of atmospheric particles for two aerodynamic diameters (0.18 and 1.8 μm) was compared using border-based fractal dimension to relate it to the other particle properties, because T1-generated particles have optical, morphological and chemical properties different from those transported by the MC plume. Particles sampled under MC pollution influence showed not much variability, suggesting that more spherical particles (border-based fractal dimension close to 1.0) are more common in larger sizes (d50 = 1.8 μm), which may be attributed to aerosol aging and secondary aerosol formation. Between 06:00 and 09:00 a.m., smaller particles (d50 = 0.18 μm) had more irregular shapes resulting in higher border-based fractal dimensions (1.2-1.3) for samples with more local influence. EDS analysis in d50 = 0.18 μm particles showed high contents of carbonaceous material, Si, Fe, K, and Co. Perhaps, this indicates an impact from industrial and vehicle emissions on atmospheric particles at T1.

  4. Optical phase curves as diagnostics for aerosol composition in exoplanetary atmospheres

    NASA Astrophysics Data System (ADS)

    Oreshenko, Maria; Heng, Kevin; Demory, Brice-Olivier

    2016-04-01

    Optical phase curves have become one of the common probes of exoplanetary atmospheres, but the information they encode has not been fully elucidated. Building on a diverse body of work, we upgrade the Flexible Modelling System to include scattering in the two-stream, dual-band approximation and generate plausible, three-dimensional structures of irradiated atmospheres to study the radiative effects of aerosols or condensates. In the optical, we treat the scattering of starlight using a generalization of Beer's law that allows for a finite Bond albedo to be prescribed. In the infrared, we implement the two-stream solutions and include scattering via an infrared scattering parameter. We present a suite of four-parameter general circulation models for Kepler-7b and demonstrate that its climatology is expected to be robust to variations in optical and infrared scattering. The westward and eastward shifts of the optical and infrared phase curves, respectively, are shown to be robust outcomes of the simulations. Assuming micron-sized particles and a simplified treatment of local brightness, we further show that the peak offset of the optical phase curve is sensitive to the composition of the aerosols or condensates. However, to within the measurement uncertainties, we cannot distinguish between aerosols made of silicates (enstatite or forsterite), iron, corundum or titanium oxide, based on a comparison to the measured peak offset (41° ± 12°) of the optical phase curve of Kepler-7b. Measuring high-precision optical phase curves will provide important constraints on the atmospheres of cloudy exoplanets and reduce degeneracies in interpreting their infrared spectra.

  5. Atmospheric Composition of Weak G Band Stars: CNO and Li Abundances

    NASA Astrophysics Data System (ADS)

    Adamczak, Jens; Lambert, David L.

    2013-03-01

    We determined the chemical composition of a large sample of weak G band stars—a rare class of G and K giants of intermediate mass with unusual abundances of C, N, and Li. We have observed 24 weak G band stars with the 2.7 m Harlan J. Smith Telescope at the McDonald Observatory and derived spectroscopic abundances for C, N, O, and Li, as well as for selected elements from Na-Eu. The results show that the atmospheres of weak G band stars are highly contaminated with CN-cycle products. The C underabundance is about a factor of 20 larger than for normal giants and the 12C/13C ratio approaches the CN-cycle equilibrium value. In addition to the striking CN-cycle signature the strong N overabundance may indicate the presence of partially ON-cycled material in the atmospheres of the weak G band stars. The exact mechanism responsible for the transport of the elements to the surface has yet to be identified but could be induced by rapid rotation of the main sequence progenitors of the stars. The unusually high Li abundances in some of the stars are an indicator for Li production by the Cameron-Fowler mechanism. A quantitative prediction of a weak G band star's Li abundance is complicated by the strong temperature sensitivity of the mechanism and its participants. In addition to the unusual abundances of CN-cycle elements and Li, we find an overabundance of Na that is in accordance with the NeNa chain running in parallel with the CN cycle. Apart from these peculiarities, the element abundances in a weak G band star's atmosphere are consistent with those of normal giants.

  6. ATMOSPHERIC COMPOSITION OF WEAK G BAND STARS: CNO AND Li ABUNDANCES

    SciTech Connect

    Adamczak, Jens; Lambert, David L.

    2013-03-10

    We determined the chemical composition of a large sample of weak G band stars-a rare class of G and K giants of intermediate mass with unusual abundances of C, N, and Li. We have observed 24 weak G band stars with the 2.7 m Harlan J. Smith Telescope at the McDonald Observatory and derived spectroscopic abundances for C, N, O, and Li, as well as for selected elements from Na-Eu. The results show that the atmospheres of weak G band stars are highly contaminated with CN-cycle products. The C underabundance is about a factor of 20 larger than for normal giants and the {sup 12}C/{sup 13}C ratio approaches the CN-cycle equilibrium value. In addition to the striking CN-cycle signature the strong N overabundance may indicate the presence of partially ON-cycled material in the atmospheres of the weak G band stars. The exact mechanism responsible for the transport of the elements to the surface has yet to be identified but could be induced by rapid rotation of the main sequence progenitors of the stars. The unusually high Li abundances in some of the stars are an indicator for Li production by the Cameron-Fowler mechanism. A quantitative prediction of a weak G band star's Li abundance is complicated by the strong temperature sensitivity of the mechanism and its participants. In addition to the unusual abundances of CN-cycle elements and Li, we find an overabundance of Na that is in accordance with the NeNa chain running in parallel with the CN cycle. Apart from these peculiarities, the element abundances in a weak G band star's atmosphere are consistent with those of normal giants.

  7. Ground-based spectroscopic measurements of atmospheric gas composition near Saint Petersburg (Russia)

    NASA Astrophysics Data System (ADS)

    Timofeyev, Yury; Virolainen, Yana; Makarova, Maria; Poberovsky, Anatoly; Polyakov, Alexander; Ionov, Dmitry; Osipov, Sergey; Imhasin, Hamud

    2016-05-01

    Since early 2009, high-resolution solar absorption spectra have been recorded at the Peterhof station (59.88°N, 29.82°E) of Saint Petersburg State University located in the suburbs of St. Petersburg. Measurements are made with the Fourier Transform Infrared (FTIR) system, which consists of Bruker IFS 125HR instrument (with maximum spectral resolution of 0.005 cm-1) and self-designed solar tracker. We derived total column (TC) of a dozen of atmospheric gases from recorded spectra and performed the error analysis of these retrievals. Furthermore, we analysed the temporal variability of the important climatically active gases, such as H2O, CH4, O3, CO, and NO2 near St. Petersburg and compared our retrievals with independent ground-based and satellite data, as well as with the results of EMAC model numerical simulations. Currently, the results of our measurements and the measuring system are under validation for entering the international Network for the Detection of Atmospheric Composition Change (NDACC).

  8. Sources or sinks? The responses of tropical forests to current and future climate and atmospheric composition.

    PubMed Central

    Clark, Deborah A

    2004-01-01

    How tropical rainforests are responding to the ongoing global changes in atmospheric composition and climate is little studied and poorly understood. Although rising atmospheric carbon dioxide (CO2) could enhance forest productivity, increased temperatures and drought are likely to diminish it. The limited field data have produced conflicting views of the net impacts of these changes so far. One set of studies has seemed to point to enhanced carbon uptake; however, questions have arisen about these findings, and recent experiments with tropical forest trees indicate carbon saturation of canopy leaves and no biomass increase under enhanced CO2. Other field observations indicate decreased forest productivity and increased tree mortality in recent years of peak temperatures and drought (strong El Niño episodes). To determine current climatic responses of forests around the world tropics will require careful annual monitoring of ecosystem performance in representative forests. To develop the necessary process-level understanding of these responses will require intensified experimentation at the whole-tree and stand levels. Finally, a more complete understanding of tropical rainforest carbon cycling is needed for determining whether these ecosystems are carbon sinks or sources now, and how this status might change during the next century. PMID:15212097

  9. Atmospheric control on isotopic composition and d-excess in water vapor over ocean surface

    NASA Astrophysics Data System (ADS)

    Fan, Naixin

    For decades, stable isotopes of water have been used as proxies to infer the variation of the hydrological cycle. However, it is still not clear how various atmospheric processes quantitatively control kinetic fractionation during evaporation over the ocean. Understanding kinetic fractionation is important in that the interpretation of the isotopic composition record preserved in ice cores and precipitation relies in part on the isotopic information at the moisture source. In addition, the isotopic composition of vapor contains information about variation of atmospheric processes such as turbulence and change in moisture source region which is useful for studying meteorological processes and climate change. In this study the isotopic composition of water vapor in the marine boundary layer (MBL) over the ocean was investigated using a combination of a newly developed marine boundary layer (MBL) model and observational data. The new model has a more realistic MBL structure than previous models and includes new features such as vertical advection of air and diffusion coefficients that vary continuously in the vertical direction. A robust linear relationship between deltaD and delta18O was found in observational oceanic water vapor data and the model can well capture the characteristics of this relationship. The individual role of atmospheric processes or variables on deltaD, delta18O and d-excess was quantitatively investigated and an overview of the combined effect of all the meteorological processes is provided. In particular, we emphasize that the properties of subsiding air (such as its mixing ratio and isotopic values) are crucial to the isotopic composition of surface water vapor. Relative humidity has been used to represent the moisture deficit that drives evaporative isotopic fluxes, however, we argue that it has serious limitations in explaining d-excess variation as latitude varies. We introduce a new quantity Gd=SST-Td, the difference between the sea

  10. The switching between zonal and blocked mid-latitude atmospheric circulation: a dynamical system perspective

    NASA Astrophysics Data System (ADS)

    Faranda, Davide; Masato, Giacomo; Moloney, Nicholas; Sato, Yuzuru; Daviaud, Francois; Dubrulle, Bérengère; Yiou, Pascal

    2016-09-01

    Atmospheric mid-latitude circulation is dominated by a zonal, westerly flow. Such a flow is generally symmetric, but it can be occasionally broken up by blocking anticyclones. The subsequent asymmetric flow can persist for several days. In this paper, we apply new mathematical tools based on the computation of an extremal index in order to reexamine the dynamical mechanisms responsible for the transitions between zonal and blocked flows. We discard the claim that mid-latitude circulation features two distinct stable equilibria or chaotic regimes, in favor of a simpler mechanism that is well understood in dynamical systems theory: we identify the blocked flow as an unstable fixed point (or saddle point) of a single basin chaotic attractor, dominated by the westerlies regime. We also analyze the North Atlantic Oscillation and the Arctic Oscillation atmospheric indices, whose behavior is often associated with the transition between the two circulation regimes, and investigate analogies and differences with the bidimensional blocking indices. We find that the Arctic Oscillation index, which can be thought as a proxy for a hemispheric average of the Tibaldi-Molteni blocking index, tracks unstable fixed points. On the other hand, the North Atlantic Oscillation, representative only for local properties of the North Atlantic blocking dynamics, does not show any trace of the presence of unstable fixed points of the dynamics.

  11. 10-year record of atmospheric composition in the high Himalayas: source, transport and impact

    NASA Astrophysics Data System (ADS)

    Bonasoni, Paolo; Laj, Paolo; Marinoni, Angela; Cristofanelli, Paolo; Maione, Michela; Putero, Davide; Calzolari, Francescopiero; Decesari, Stefano; Facchini, Maria Cristina; Fuzzi, Sandro; Gobbi, Gianpaolo; Sellegri, Karine; Verza, Gianpietro; Vuillermoz, Elisa; Arduini, Jgor

    2016-04-01

    occurrence of pollution transport and high rate of new particle formation events in this region. Here we provide an overview of the main scientific results obtained during these ten years of research. In particular, we will discuss the impact of atmospheric transport and monsoon variability on atmospheric composition by disentangling the role played by mountain breeze system and synoptic-scale transport. We will provide specific information about the role of stratospheric intrusions, long-range mineral dust transport and open biomass burning emissions in determining the variability of ozone, aerosol and equivalent black carbon concentrations. The effect of particle nucleation processes on aerosol number concentrations will be shown. Finally, we discuss the climatic impact of aerosols observed at NCO-P both in terms of direct atmospheric radiative forcing and black carbon deposition on Himalayan snow.

  12. Impact of Dynamical Downscaling on Model Representation of Land-Atmosphere Coupling Strength

    NASA Astrophysics Data System (ADS)

    Santanello, J. A., Jr.; Roundy, J. K.; Ferguson, C. R.

    2015-12-01

    Extremes in the water cycle, such as drought and flood, threaten the sustainability of water resources and cause significant impacts on society that will likely increase due to growing populations and a changing climate. Reducing the impact of extreme events requires preparations enabled by reliable and relevant predictions of the climate. Climate predictions are made using Global Climate Models (GCMs) that typically have spatial resolutions that are too course for application at the local level where the prediction is needed to ensure a society resilient to extremes. Therefore, a common practice is to dynamically downscale results from GCM's using a regional model that can provide predictions at scales consistent with the application. Downscaled predictions are dependent on model physics and model setup (e.g. boundary conditions, nudging) and as a result the overall validity of dynamically downscaling has not been fully demonstrated to date. NASA has recently sponsored an intra-agency downscaling project to better understand the validity of dynamical downscaling. As part of this project, several 10-year simulations of the NASA Unified Weather Research and Forecast (NU-WRF) model that vary in resolution and large scale nudging were used to downscale MERRA-2 reanalyses over the continental U.S. This work leverages these model runs in order to understand the impact of model resolution and nudging on the representation of land-atmosphere coupling strength and its impact on downscaled predictions of the water cycle. The representation of land-atmosphere coupling strength is analyzed through a suite of local land-atmosphere coupling (LoCo) metrics that are compared across downscaling runs as well as coarse scale predictions from GEOS-5 and MERRA-2. The impact of downscaling approaches and resolution on the representation of land-atmosphere coupling is presented and the implications for future downscaling applications are discussed.

  13. Understanding the historical trend in atmospheric methane using its carbon isotopic composition 1978 to 1998

    NASA Astrophysics Data System (ADS)

    Teama, D. G.; Rice, A. L.

    2010-12-01

    Methane (CH4) is one of the most important greenhouse gases with a global warming potential of 25 based on a 100 year time horizon. Its concentration has more than doubled since dawn of the industrial era, primarily due to anthropogenic practices such as fossil fuel production, rice cultivation, biomass burning and waste management. The rate of increase, however, is not constant and fluctuates on short and long timescales due to the dynamical interaction of CH4 sources and sinks. One powerful tool to identify changes in sources and sinks of atmospheric CH4 is the use of stable isotopes. By comparing trends in the 13C/12C (δ13C) and D/H (δD) content of atmospheric CH4 in time series to the isotopic signatures of sources, we can potentially disentangle trends in methane sources and sinks. In this work we focus on the period 1978-1998, a period that experienced a dramatic slow-down in the growth rate of atmospheric CH4. We present measurements of δ13C of CH4 from a unique archive of nearly 200 air samples collected at Cape Meares, Oregon (45.5oN, 124oW). The measurements indicate enrichment in δ13C of 0.017 (±.003) ‰ yr-1 over the whole time period. Deeper analysis, however, show that δ13C enrichment from 1978 through the end of 1988 has smaller rate of change (0.01 ‰ yr-1) than from 1988 to 1998 (0.02 ‰ yr-1). As it is integral to our work, sample stability of the archive is also investigated by comparing modern measurements of CH4 mixing ratio to the original determinations of archive samples. Finally, we discuss implications for CH4 sources over this time period and compare our results to findings in prior work.

  14. A review of dynamic mechanical characterization of high temperature PMR polyimides and composites

    NASA Technical Reports Server (NTRS)

    Pater, Ruth H.

    1988-01-01

    This paper reviews the applications of dynamic mechanical characterization for high-temperature PMR polyimides and their graphite-fiber-reinforced composites. This characterization technique provides insights into the processability, performance, and structure property relationships of the polyimides and composites. The dynamic mechanical properties of various molding powders, commercially obtained prepregs, neat resins, and as-fabricated as well as aged composites are presented. Some applied aspects of the dynamic mechanical data are discussed.

  15. Dynamics and predictability of a low-order wind-driven ocean - atmosphere model

    NASA Astrophysics Data System (ADS)

    Vannitsem, Stéphane

    2013-04-01

    The dynamics of a low order coupled wind-driven Ocean-Atmosphere (OA) system is investigated with emphasis on its predictability properties. The low-order coupled deterministic system is composed of a baroclinic atmosphere for which 12 dominant dynamical modes are only retained (Charney and Straus, 1980) and a wind-driven, quasi-geostrophic and reduced-gravity shallow ocean whose field is truncated to four dominant modes able to reproduce the large scale oceanic gyres (Pierini, 2011). The two models are coupled through mechanical forcings only. The analysis of its dynamics reveals first that under aperiodic atmospheric forcings only dominant single gyres (clockwise or counterclockwise) appear. This feature is expected to be related with the specific domain choice over which the coupled system is defined. Second the dynamical quantities characterizing the short-term predictability (Lyapunov exponents, Lyapunov dimension, Kolmogorov-Sinaï (KS) entropy) displays a complex dependence as a function of the key parameters of the system, namely the coupling strength and the external thermal forcing. In particular, the KS-entropy is increasing as a function of the coupling in most of the experiments, implying an increase of the rate of loss of information about the localization of the system on his attractor. Finally the dynamics of the error is explored and indicates, in particular, a rich variety of short term behaviors of the error in the atmosphere depending on the (relative) amplitude of the initial error affecting the ocean, from polynomial (at2 + bt3 + ct4) up to purely exponential evolutions. These features are explained and analyzed in the light of the recent findings on error growth (Nicolis et al, 2009). References Charney J G, Straus DM (1980) Form-Drag Instability, Multiple Equilibria and Propagating Planetary Waves in Baroclinic, Orographically Forced, Planetary Wave Systems. J Atmos Sci 37: 1157-1176. Nicolis C, Perdigao RAP, Vannitsem S (2009) Dynamics of

  16. Mantle dynamics and the atmospheres of Mars and Venus: implications for surface conditions and interactions.

    NASA Astrophysics Data System (ADS)

    Gillmann, C.; Tackley, P.

    2012-04-01

    We propose to investigate the interaction between the mantle and the atmosphere of terrestrial planets, in order to study whereas such coupling could be the cause of the divergent evolution of planets in our solar system. Therefore, we build a coupled model taking into account mantle dynamics, volatile exchanges and atmospheric processes. We focus on Mars and Venus and consider the evolution of CO2 and H2O in the atmosphere. The first main mechanism we consider is the volcanic source of volatiles. Therefore we need to model the mantle dynamics by adapting the highly advanced StagYY code (developed by P. Tackley, 2008) for Mars and Venus. When possible, we compare those results to published modeling (Breuer and Spohn, 2006; Grott et al., 2011) and observation. Atmospheric escape is considered as the main volatile loss flux. Early loss is thermal, caused by hydrodynamic escape. After the first few hundred million years, the main atmospheric escape flux is caused by non-thermal mechanisms. We model their evolution by comparing recent numerical study and ASPERA (Analyzer of Space Plasma and EneRgetic Atoms) measurements. We combine these models to calculate the state of the atmosphere of Venus and Mars. This lets us estimate the surface temperature of those planets either from a Mars Global Circulation Model (e.g. Forget at al., 1999), or with a gray radiative-convective atmosphere model, for Venus. In the case of Mars, we show that the present-day atmosphere of Mars is likely to be constituted by a large part (more than 50%) of volcanic gases emitted since 4 billion years ago, which corresponds to a mean age of 1.9 to 2.3 Gyr. The variations of CO2 pressure over this period seem relatively low (50 mbar at most). This seems in line with the assumption that the heavy loss of volatiles occurred before 500 Myr. Surface temperature variations are likely to be small (several Kelvin) and would not be responsible for periods of flowing liquid surface water by themselves

  17. Dynamic fracture behaviour in fibre-reinforced cementitious composites

    NASA Astrophysics Data System (ADS)

    Yu, Rena C.; Cifuentes, Héctor; Rivero, Ignacio; Ruiz, Gonzalo; Zhang, Xiaoxin

    2016-08-01

    The object of this work is to simulate the dynamic fracture propagation in fibre-reinforced cementitious composites, in particular, in steel fibre reinforced concrete (SFRC). Beams loaded in a three-point bend configuration through a drop-weight impact device are considered. A single cohesive crack is assumed to propagate at the middle section; the opening of this crack is governed by a rate-dependent cohesive law; the fibres around the fracture plane are explicitly represented through truss elements. The fibre pull-out behaviour is depicted by an equivalent constitutive law, which is obtained from an analytical load-slip curve. The obtained load-displacement curves and crack propagation velocities are compared with their experimental counterparts. The good agreement with experimental data testifies to the feasibility of the proposed methodology and paves the way to its application in a multi-scale framework.

  18. Display life of sheep meats retail packaged under atmospheres of various volumes and compositions.

    PubMed

    Kennedy, C; Buckley, D J; Kerry, J P

    2004-12-01

    Longissmus dorsi loins were removed from Suffolk cross-breed lambs (4-9 months) and hoggets (15-20 months). The effect of package gas composition was investigated by packaging loins with gas mixtures containing 80:20:0, 60:20:20 and 60:40:0/O(2):CO(2):N(2) with a 2:1 headspace to meat volume ratio. The most effective gas mixture for prolonging shelf-life was used to study the effect of different headspace to meat volume ratios. Loins were packaged with a headspace to meat volume ratio of 2:1, 1.5:1 or 1:1. All modified atmosphere (MA) packs were held under refrigerated display conditions (4 °C, 616 lx) for 12 days. Loins were assessed for microbial, oxidative and colour stability and headspace composition every 3 days. The 80:20:0/O(2):CO(2):N(2) gas composition and the 2:1 headspace to meat volume ratio was the most effective packaging combination at maintaining and prolonging the attractive red colour of MA packaged lamb and hogget meat. 80:20:0/O(2):CO(2):N(2) resulted in significantly (p<0.01) higher Hunter a values in lamb. The 2:1 ratio gave higher visual assessment values in lamb and higher Hunter `a' values for hogget meat throughout the trial. The 2:1 ratio was the most effective at decreasing Pseudomonas and increasing the numbers of lactic acid bacteria in the total microbial load in both lamb and hogget meat. Lipid oxidation in lamb and hogget meat occurred at a slower comparative rate than discolouration or microbial growth and was not the major determinant of shelf-life. The 2:1 headspace to meat volume ratio was most effective at maintaining the initial gas mix in both lamb and hogget MA packs.

  19. Coupling the atmosphere with interior dynamics: Implications for the resurfacing of Venus

    NASA Astrophysics Data System (ADS)

    Noack, L.; Breuer, D.; Spohn, T.

    2012-02-01

    We calculated 2D and 3D mantle convection models for Venus using digitized atmosphere temperatures from the model of Bullock and Grinspoon (Bullock, M.A., Grinspoon, D.H. [2001]. Icarus 150, 19-37) to study the interaction between interior dynamics and atmosphere thermal evolution. The coupling between atmosphere and interior occurs through mantle degassing and the effect of varying concentrations of the greenhouse gas H 2O on the surface temperature. Exospheric loss of hydrogen to space is accounted for as a H 2O sink. The surface temperature enters the mantle convection model as a boundary condition. Our results suggest a self-consistent feedback mechanism between the interior and the atmosphere resulting in spatial-temporal surface renewal. Greenhouse warming of the atmosphere results in an increase in the surface temperature. Whenever the surface temperature reaches a critical value, the viscosity difference across the lithosphere becomes smaller than about 10 5 and the surface becomes locally mobile. The critical surface temperature depends on the activation energy for mantle creep, the stress exponent in the non-Newtonian mantle rheology law, and the mantle temperature. Surface renewal together with surface lava flow may explain why the surface of Venus is young on average, i.e. not older than a few hundred million years. The mobilization of the near-surface lithosphere increases the rate of heat removal from the mantle and thereby the interior cooling rate. The enhanced cooling results in a reduction of the water outgassing rates. As a consequence of decreasing water concentrations in the atmosphere, the surface temperature decreases. Our model calculations suggest that Venus should have been geologically active until recently. This is in agreement with several lines of observational evidence from thermal emissivity measurements and crater distribution analyses.

  20. Dynamics of the Venus upper atmosphere: Outstanding problems and new constraints expected from Venus Express

    NASA Astrophysics Data System (ADS)

    Bougher, S. W.; Rafkin, S.; Drossart, P.

    2006-11-01

    A consistent picture of the dynamics of the Venus upper atmosphere from ˜90 to 200 km has begun to emerge [e.g., Bougher, S.W., Alexander, M.J., Mayr, H.G., 1997. Upper Atmosphere Dynamics: Global Circulation and Gravity Waves. Venus II, CH. 2.4. University of Arizona Press, Tucson, pp. 259-292; Lellouch, E., Clancy, T., Crisp, D., Kliore, A., Titov, D., Bougher, S.W., 1997. Monitoring of Mesospheric Structure and Dynamics. Venus II, CH. 3.1. University of Arizona Press, Tucson, pp. 295-324]. The large-scale circulation of the Venus upper atmosphere (upper mesosphere and thermosphere) can be decomposed into two distinct flow patterns: (1) a relatively stable subsolar-to-antisolar (SS-AS) circulation cell driven by solar heating, and (2) a highly variable retrograde superrotating zonal (RSZ) flow. Wave-like perturbations have also been observed. However, the processes responsible for maintaining (and driving variations in) these SS-AS and RSZ winds are not well understood. Variations in winds are thought to result from gravity wave breaking and subsequent momentum and energy deposition in the upper atmosphere [Alexander, M.J., 1992. A mechanism for the Venus thermospheric superrotation. Geophys. Res. Lett. 19, 2207-2210; Zhang, S., Bougher, S.W., Alexander, M.J., 1996. The impact of gravity waves on the Venus thermosphere and O2 IR nightglow. J. Geophys. Res. 101, 23195-23205]. However, existing data sets are limited in their spatial and temporal coverage, thereby restricting our understanding of these changing circulation patterns. One of the major goals of the Venus Express (VEX) mission is focused upon increasing our understanding of the circulation and dynamical processes of the Venus atmosphere up to the exobase [Titov, D.V., Lellouch, E., Taylor, F.W., 2001. Venus Express: Response to ESA's call for ideas for the re-use of the Mars Express platform. Proposal to European Space Agency, 1-74]. Several VEX instruments are slated to obtain remote measurements

  1. Resolution and Dynamical Core Dependence of Atmospheric River Frequency in Global Model Simulations

    SciTech Connect

    Hagos, Samson M.; Leung, Lai-Yung R.; Yang, Qing; Zhao, Chun; Lu, Jian

    2015-04-01

    This study examines the sensitivity of atmospheric river (AR) frequency simulated by a global model with different grid resolutions and dynamical cores. Analysis is performed on aquaplanet simulations using version 4 of Community Atmosphere Model (CAM4) at 240, 120, 60 and 30 km model resolutions each with the Model for Prediction Across Scales (MPAS) and High-Order Methods Modeling Environment (HOMME) dynamical cores. The frequency of AR events decreases with model resolution and the HOMME dynamical core produces more AR events than MPAS. Comparing the frequencies determined using absolute and percentile thresholds of large-scale conditions used to define an AR, model sensitivity is found to be related to the overall sensitivity of sub-tropical westerlies, atmospheric precipitable water content and profile and to a lesser extent on extra-tropical Rossby wave activity to model resolution and dynamical core. Real world simulations using MPAS at 120 km and 30 km grid resolutions also exhibit a decrease of AR frequency with increasing resolution over southern East Pacific, but there difference is smaller over northern East Pacific. This inter-hemispheric difference is related to the enhancement of convection in over the tropics with increased resolution. This anomalous convection sets off Rossby wave patterns that weaken the subtropical westerlies over southern East Pacific but have relatively little effect on those over northern East Pacific. In comparison to NCEP2 reanalysis, MPAS real world simulations are found to underestimate AR frequencies at both resolutions likely because of their climatologically drier sub-tropics and poleward shifted jets. This study highlights the important links between model climatology of large-scale conditions and extremes.

  2. Dynamic characteristics of atmospheric planetary waves during stratospheric warmings in winter 2008

    NASA Astrophysics Data System (ADS)

    Chernigovskaya, Marina; Medvedev, Andrey; Tolstikov, Maxim; Medvedeva, Irina; Ratovsky, Konstantin

    2010-05-01

    The wave mechanism of energy transfer is quite significant in transferring energy in the Earth's atmosphere. Atmospheric internal waves of different spatial and temporal scales (including 1-30-day planetary waves) transfer a great deal of kinetic energy from the troposphere and stratosphere to higher atmospheric layers. As deduced from experimental data, systems of strong zonal stratospheric winds prevent penetration of planetary waves from the troposphere to the upper atmosphere (mesosphere and thermosphere), but the part of their energy reaches the upper atmosphere. Planetary waves are in many respects associated with such interesting phenomena in the Earth's stratosphere as sudden winter stratospheric warmings (SSW), observed almost every winter and characterized by geographical nonuniformity. High concentration of stratospheric warming centers is typical of the Asian region of Russia. We examined dynamic characteristics of atmospheric planetary waves observed in the Asian region of Russia in the longitudinal sector of ~80-125°E during stratospheric warmings in winter 2008. Satellite data on vertical temperature distribution obtained by the Microwave Limb Sounder (MLS) aboard the spacecraft EOS Aura and Irkutsk digisonde DPS-4 data were used. It has been established that pronounced wave-like temperature disturbances with characteristic periods of 10-14 days were observed in the Asian region of Russia in the sector of ~80-125°E and 40-64°N over a height range of 20-90 km during development of the SSW in January-February 2008. Revealed here is a high correlation between temperature disturbances and the minimum frequency of reflection in the Irkutsk digisonde DPS-4 ionograms. This paper offers a method for investigating characteristics of propagation of long-term temperature disturbances by a cross-correlation analysis. This method consists in determining delays between disturbances observed at different points and in deriving a system of linear equations for

  3. Model Study of IGW Hotspot Implications for the Middle Atmospheric Dynamics and Transport

    NASA Astrophysics Data System (ADS)

    Pisoft, P.; Šácha, P.; Jacobi, C.; Lilienthal, F.

    2015-12-01

    Internal gravity waves are widely recognized to contribute significantly to the energy and angular momentum transport. They play a significant role in affecting many of the middle atmospheric phenomena (like the QBO or Brewer-Dobson circulation). Using GPS RO density profiles, we have discovered a localized area of enhanced IGW activity and breaking in the lower stratosphere of Eastern Asia/North-western Pacific region. With a 3D primitive equation model of the middle atmosphere we studied the effects of such a localized breaking region on large-scale dynamics and transport. Enhancing artificially a gravity wave drag in the lover stratosphere of the EA/NP region we show that such a localized IGW forcing creates planetary waves propagating both equatorward and poleward and upward along the edge of the polar vortex. Possible consequences for the polar vortex stability and stratosphere-troposphere exchange in the tropical region are discussed. Finally, applying 3D wave activity flux and 3D residual circulation diagnostics, we investigated the possible role of this area in the longitudinal variability of the Brewer- Dobson circulation with a hypothesis of its enhanced downwelling branch in this region. In the process, model results were compared with the ozone and tracer distribution data from GOME, GOMOS, MIPAS and SCIAMACHY further confirming an importance of the Eastern Asia/North-western Pacific region for the middle atmospheric dynamics.

  4. Characterization of atmosphere-water exchange processes of CO 2 in estuaries using dynamic simulation

    NASA Astrophysics Data System (ADS)

    García-Luque, E.; Forja, J. M.; Gómez-Parra, A.

    2005-12-01

    CO 2 is one of the so-called "greenhouse effect" gases; therefore, its rates of water-atmosphere exchange are very relevant for studies of climate change. Coastal zones (which include estuarine systems) are of special interest in relation to the global carbon cycle. Thus, an estuary simulator, which operates in a dynamic mixing regime, is specifically applied in an initial study of the estuarine dynamic of inorganic carbon, focusing basically on the influence of salinity and pH on the water-atmosphere fluxes of CO 2 in these zones. The simulation has been performed under two assumptions: (i) considering that the system is subjected to a stationary gradient of salinity and (ii) taking into account the effect of the tides, owing to the daily oscillations introduced by this phenomenon in the process of CO 2 transfer between the water and the atmosphere. After analysing the results, it has been observed that a potential source of error exists when choosing the coefficients of gas exchange ( k) for CO 2 studies. Nevertheless, the evolution of CO 2 fluxes along the salinity and pH gradients achieved shows the same trends with those observed in a wide variety of real estuaries described in the related literature.

  5. Cluster Analysis of Atmospheric Dynamics and Pollution Transport in a Coastal Area

    NASA Astrophysics Data System (ADS)

    Sokolov, Anton; Dmitriev, Egor; Maksimovich, Elena; Delbarre, Hervé; Augustin, Patrick; Gengembre, Cyril; Fourmentin, Marc; Locoge, Nadine

    2016-11-01

    Summertime atmospheric dynamics in the coastal zone of the industrialized Dunkerque agglomeration in northern France was characterized by a cluster analysis of back trajectories in the context of pollution transport. The MESO-NH atmospheric model was used to simulate the local dynamics at multiple scales with horizontal resolution down to 500 m, and for the online calculation of the Lagrangian backward trajectories with 30-min temporal resolution. Airmass transport was performed along six principal pathways obtained by the weighted k-means clustering technique. Four of these centroids corresponded to a range of wind speeds over the English Channel: two for wind directions from the north-east and two from the south-west. Another pathway corresponded to a south-westerly continental transport. The backward trajectories of the largest and most dispersed sixth cluster contained low wind speeds, including sea-breeze circulations. Based on analyses of meteorological data and pollution measurements, the principal atmospheric pathways were related to local air-contamination events. Continuous air quality and meteorological data were collected during the Benzene-Toluene-Ethylbenzene-Xylene 2006 campaign. The sites of the pollution measurements served as the endpoints for the backward trajectories. Pollutant transport pathways corresponding to the highest air contamination were defined.

  6. A comparison of atmospheric composition using the Carbon Bond and Regional Atmospheric Chemistry MechanismsChemistry Mechanisms

    EPA Science Inventory

    We incorporate the recently developed Regional Atmospheric Chemistry Mechanism (version 2, RACM2) into the Community Multiscale Air Quality modeling system for comparison with the existing 2005 Carbon Bond mechanism with updated toluene chemistry (CB05TU). Compared to CB05TU, RAC...

  7. Ion Dynamics in Organic-Inorganic Composite Superionic Conductor Glasses

    SciTech Connect

    Asayama, Ryo; Kuwata, Naoaki; Kawamura, Junichi

    2006-05-05

    Ionic conductivity of organic-inorganic composite superionic conductor glasses composed of AgI and alkylammoniumiodides is measured as a function of frequency, temperature and composition. A clear transition from insulator to superionic conductor is confirmed at the volume fraction {phi} of AgI is about 35 %. The dc component of the conductivity is fitted to the {sigma}{approx}({phi}-{phi}c){mu} with {phi}c=0.36, {mu}=2.5 for the present data. Near the percolation threshold, a power-law type frequency dependence of {omega}n (n{approx}0.67) is seen in mid frequency and {omega}1.0 at higher frequency corresponding to the constant loss region power-law is observed. The activation energies and preexponential factors derived from the temperature dependence increase from 0.3 to 0.7 eV approaching to the threshold. From these results, the ion dynamics in these glasses can be explained by the static site percolation theory at first approximation, but require the consideration on the chemical bond variation between the Ag and I modified by the organic ions.

  8. Simulation of Degraded Properties of 2D plain Woven C/SiC Composites under Preloading Oxidation Atmosphere

    NASA Astrophysics Data System (ADS)

    Chen, Xihui; Sun, Zhigang; Sun, Jianfen; Song, Yingdong

    2017-02-01

    In this paper, a numerical model which incorporates the oxidation damage model and the finite element model of 2D plain woven composites is presented for simulation of the oxidation behaviors of 2D plain woven C/SiC composite under preloading oxidation atmosphere. The equal proportional reduction method is firstly proposed to calculate the residual moduli and strength of unidirectional C/SiC composite. The multi-scale method is developed to simulate the residual elastic moduli and strength of 2D plain woven C/SiC composite. The multi-scale method is able to accurately predict the residual elastic modulus and strength of the composite. Besides, the simulated residual elastic moduli and strength of 2D plain woven C/SiC composites under preloading oxidation atmosphere show good agreements with experimental results. Furthermore, the preload, oxidation time, temperature and fiber volume fractions of the composite are investigated to show their influences upon the residual elastic modulus and strength of 2D plain woven C/SiC composites.

  9. Atmospheric Dynamics on Venus, Jupiter, and Saturn: An Observational and Analytical Study

    NASA Technical Reports Server (NTRS)

    Bridger, Alison; Magalhaes, Julio A.; Young, Richard E.

    2000-01-01

    Determining the static stability of Jupiter's atmosphere below the visible cloud levels is important for understanding the dynamical modes by which energy and momentum are transported through Jupiter's deep troposphere. The Galileo Probe Atmospheric Structure Investigation (ASI) employed pressure and temperature sensors to directly measure these state variables during the parachute-descent phase, which started at a pressure (p) of 0.4 bars and ended at p= 22 bars. The internal temperature of the probe underwent large temperature fluctuations which significantly exceeded design specifications. Corrections for these anomalous interior temperatures have been evaluated based on laboratory data acquired after the mission using the flight spare hardware. The corrections to the pressure sensor readings was particularly large and the uncertainties in the atmospheric pressures derived from the p sensor measurements may still be significant. We have sought to estimate the formal uncertainties in the static stability derived from the p and T sensor measurements directly and to devise means of assessing the static stability of Jupiter's atmosphere which do not rely on the p sensor data.

  10. Impact of preindustrial to present-day changes in short-lived pollutant emissions on atmospheric composition and climate forcing

    NASA Astrophysics Data System (ADS)

    Naik, Vaishali; Horowitz, Larry W.; Fiore, Arlene M.; Ginoux, Paul; Mao, Jingqiu; Aghedo, Adetutu M.; Levy, Hiram

    2013-07-01

    We describe and evaluate atmospheric chemistry in the newly developed Geophysical Fluid Dynamics Laboratory chemistry-climate model (GFDL AM3) and apply it to investigate the net impact of preindustrial (PI) to present (PD) changes in short-lived pollutant emissions (ozone precursors, sulfur dioxide, and carbonaceous aerosols) and methane concentration on atmospheric composition and climate forcing. The inclusion of online troposphere-stratosphere interactions, gas-aerosol chemistry, and aerosol-cloud interactions (including direct and indirect aerosol radiative effects) in AM3 enables a more complete representation of interactions among short-lived species, and thus their net climate impact, than was considered in previous climate assessments. The base AM3 simulation, driven with observed sea surface temperature (SST) and sea ice cover (SIC) over the period 1981-2007, generally reproduces the observed mean magnitude, spatial distribution, and seasonal cycle of tropospheric ozone and carbon monoxide. The global mean aerosol optical depth in our base simulation is within 5% of satellite measurements over the 1982-2006 time period. We conduct a pair of simulations in which only the short-lived pollutant emissions and methane concentrations are changed from PI (1860) to PD (2000) levels (i.e., SST, SIC, greenhouse gases, and ozone-depleting substances are held at PD levels). From the PI to PD, we find that changes in short-lived pollutant emissions and methane have caused the tropospheric ozone burden to increase by 39% and the global burdens of sulfate, black carbon, and organic carbon to increase by factors of 3, 2.4, and 1.4, respectively. Tropospheric hydroxyl concentration decreases by 7%, showing that increases in OH sinks (methane, carbon monoxide, nonmethane volatile organic compounds, and sulfur dioxide) dominate over sources (ozone and nitrogen oxides) in the model. Combined changes in tropospheric ozone and aerosols cause a net negative top-of-the-atmosphere

  11. Dynamic composition, shaping and organization of plastid nucleoids

    PubMed Central

    Powikrowska, Marta; Oetke, Svenja; Jensen, Poul E.; Krupinska, Karin

    2014-01-01

    In this article recent progress on the elucidation of the dynamic composition and structure of plastid nucleoids is reviewed from a structural perspective. Plastid nucleoids are compact structures of multiple copies of different forms of ptDNA, RNA, enzymes for replication and gene expression as well as DNA binding proteins. Although early electron microscopy suggested that plastid DNA is almost free of proteins, it is now well established that the DNA in nucleoids similarly as in the nuclear chromatin is associated with basic proteins playing key roles in organization of the DNA architecture and in regulation of DNA associated enzymatic activities involved in transcription, replication, and recombination. This group of DNA binding proteins has been named plastid nucleoid associated proteins (ptNAPs). Plastid nucleoids are unique with respect to their variable number, genome copy content and dynamic distribution within different types of plastids. The mechanisms underlying the shaping and reorganization of plastid nucleoids during chloroplast development and in response to environmental conditions involve posttranslational modifications of ptNAPs, similarly to those changes known for histones in the eukaryotic chromatin, as well as changes in the repertoire of ptNAPs, as known for nucleoids of bacteria. Attachment of plastid nucleoids to membranes is proposed to be important not only for regulation of DNA availability for replication and transcription, but also for the coordination of photosynthesis and plastid gene expression. PMID:25237313

  12. A stochastic-dynamic model for global atmospheric mass field statistics

    NASA Technical Reports Server (NTRS)

    Ghil, M.; Balgovind, R.; Kalnay-Rivas, E.

    1981-01-01

    A model that yields the spatial correlation structure of atmospheric mass field forecast errors was developed. The model is governed by the potential vorticity equation forced by random noise. Expansion in spherical harmonics and correlation function was computed analytically using the expansion coefficients. The finite difference equivalent was solved using a fast Poisson solver and the correlation function was computed using stratified sampling of the individual realization of F(omega) and hence of phi(omega). A higher order equation for gamma was derived and solved directly in finite differences by two successive applications of the fast Poisson solver. The methods were compared for accuracy and efficiency and the third method was chosen as clearly superior. The results agree well with the latitude dependence of observed atmospheric correlation data. The value of the parameter c sub o which gives the best fit to the data is close to the value expected from dynamical considerations.

  13. Dynamic controlled atmosphere and ultralow oxygen storage on 'Gala' mutants quality maintenance.

    PubMed

    Thewes, Fabio Rodrigo; Both, Vanderlei; Brackmann, Auri; Weber, Anderson; de Oliveira Anese, Rogerio

    2015-12-01

    The aim of the present work was to compare the effect of ultralow oxygen (ULO) with dynamic controlled atmosphere (DCA) and controlled atmosphere (CA) on the post storage quality of 'Royal Gala' and 'Galaxy' apples after long-term storage. Two experiments were carried out with 'Royal Gala' and 'Galaxy' apples, in the years 2012 and 2013, respectively. A higher internal ethylene concentration was observed in fruits stored under CA; intermediate concentration in fruits under ULO; and the lowest by fruits stored under DCA-CF (DCA based on chlorophyll fluorescence). Flesh firmness was higher in fruits stored under DCA-CF and ULO differing from CA, in the year 2012, but in 2013 fruits stored under ULO showed the highest flesh firmness, differing from CA fruits. DCA-CF is efficient in quality maintenance of 'Royal Gala' and 'Galaxy' apples. Both 'Gala' mutants stored under ULO show a similar quality maintenance to those stored under DCA-CF.

  14. Rarefied gas dynamic effects on mass spectrometric studies of upper planetary atmospheres

    NASA Technical Reports Server (NTRS)

    French, J. B.; Reid, N. M.; Nier, A. O.; Hayden, J. L.

    1975-01-01

    Results are presented of measurements obtained with an open-source mass spectrometer both in earth orbit and in a laboratory molecular beam facility. The mass spectrometer/ion source combination was developed in the laboratory to be operable in either of two modes by altering ion extraction potential on ground command, i.e., as a stagnation cavity or to respond only to the incoming molecules of the unperturbed atmosphere. Results indicate that the use of this open-source configuration and dual-mode capability, allied with both standard static calibration and dynamic calibration using high-speed molecular beam techniques in the laboratory, allows collection of useful data on aeronomy of the upper atmosphere of planets and comet tails.

  15. Dynamical and thermodynamical modulations of future changes in landfalling atmospheric rivers over North America

    SciTech Connect

    Gao, Yang; Lu, Jian; Leung, Lai-Yung R.; Yang, Qing; Hagos, Samson M.; Qian, Yun

    2015-09-12

    This study examines the changes of landfalling atmospheric rivers (ARs) over the west coast of North America in response to future warming using model outputs from the Coupled Model Intercomparison Project phase 5 (CMIP5). The result reveals a strikingly large magnitude of increase of AR days by the end of the 21st century in the RCP8.5 climate change scenario, with fractional increases ranging between ~50% and 600%, depending on the seasons and the landfall locations. These increases are predominantly controlled by the super-Clausius-Clapeyron rate of increase of atmospheric water vapor with warming, while changes of winds that transport moisture in the ARs, or dynamical effect, mostly counter the thermodynamical effect of increasing water vapor, limiting the increase of AR events in the future. The consistent negative effect of wind changes on AR days during spring and fall can be further linked to the robust poleward shift of the subtropical jet in the North Pacific basin.

  16. Middle Atmosphere Dynamics with Gravity Wave Interactions in the Numerical Spectral Model: Tides and Planetary Waves

    NASA Technical Reports Server (NTRS)

    Mayr, Hans G.; Mengel, J. G.; Chan, K. L.; Huang, F. T.

    2010-01-01

    As Lindzen (1981) had shown, small-scale gravity waves (GW) produce the observed reversals of the zonal-mean circulation and temperature variations in the upper mesosphere. The waves also play a major role in modulating and amplifying the diurnal tides (DT) (e.g., Waltersheid, 1981; Fritts and Vincent, 1987; Fritts, 1995a). We summarize here the modeling studies with the mechanistic numerical spectral model (NSM) with Doppler spread parameterization for GW (Hines, 1997a, b), which describes in the middle atmosphere: (a) migrating and non-migrating DT, (b) planetary waves (PW), and (c) global-scale inertio gravity waves. Numerical experiments are discussed that illuminate the influence of GW filtering and nonlinear interactions between DT, PW, and zonal mean variations. Keywords: Theoretical modeling, Middle atmosphere dynamics, Gravity wave interactions, Migrating and non-migrating tides, Planetary waves, Global-scale inertio gravity waves.

  17. Radiative transfer in the dynamic atmospheres of long period variable stars

    NASA Technical Reports Server (NTRS)

    Luttermoser, Donald G.; Bowen, George H.

    1990-01-01

    An iterative procedure is presented for determining the thermal structure and dynamics of Mira-type stellar atmospheres, where the non-LTE radiative transfer code PANDORA is used in conjunction with the Bowen hydrodynamics code of Iowa State University. Preliminary results are reported for an atmospheric model of a pulsating AGB star of 1 solar mass, 240 solar radii, Teff = 3000 K, and a period of 320 days. At the present time, H, H(-), Mg I, and Mg II radiative transfer calculations have been completed and synthetic spectra are shown for H-alpha. The radiative transfer calculations demonstrate that cooling in the innermost shock of the original Bowen model is underestimated due to the omission of various hydrogen transitions. These initial results suggest that the main shock of the Bowen models are too hot and/or too deep.

  18. Radiation and dynamics in Titan's atmosphere: Investigations of Titan's present and past climate

    NASA Astrophysics Data System (ADS)

    Lora, Juan Manuel

    This dissertation explores the coupling between radiative and three-dimensional dynamical processes in the atmosphere of Titan, and their impact on the seasonal climate and recent paleoclimate. First, a simple calculation is used to demonstrate the atmospheric attenuation on the distribution of insolation. The maximum diurnal-mean surface insolation does not reach the polar regions in summertime, and this impacts both surface temperatures and their destabilizing effect on the atmosphere. Second, a detailed two-stream, fully non-gray radiative transfer model, written specifically for Titan but with high flexibility, is used to calculate radiative fluxes and the associated heating rates. This model reproduces Titan's temperature structure from the surface through the stratopause, over nearly six decades of pressure. Additionally, a physics parameterizations package is developed for Titan, in part based on similar methods from Earth atmospheric models, for use in a Titan general circulation model (GCM). Simulations with this model, including Titan's methane cycle, reproduce two important observational constraints---Titan's temperature profile and atmospheric superrotation---that have proven difficult to satisfy simultaneously for previous models. Simulations with the observed distribution of seas are used to examine the resulting distribution of cloud activity, atmospheric humidity, and temperatures, and show that these are consistent with dry mid- and low-latitudes, while the observed polar temperatures are reproduced as a consequence of evaporative cooling. Analysis of the surface energy budget shows that turbulent fluxes react to the surface insolation, confirming the importance of its distribution. Finally, the GCM is used to simulate Titan's climate during snapshots over the past 42 kyr that capture the amplitude range of variations in eccentricity and longitude of perihelion. The results show that the atmosphere is largely insensitive to orbital forcing, and

  19. Impacts of herbaceous bioenergy crops on atmospheric volatile organic composition and potential consequences for global climate change

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The introduction of new crops to agroecosystems can change the chemical composition of the atmosphere by altering the bouquet of plant-derived biogenic volatile organic compounds (BVOCs). BVOCs are low molecular weight secondary metabolites that are generally used by plants for defense, pollination ...

  20. Rising atmospheric CO2 effects on productivity and plant composition differs among soils in southern plains tallgrass prairie

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rising atmospheric CO2 concentrations are expected to alter grassland ecosystem structure and function, and may have contributed to the current level of woody encroachment. But critical questions remain regarding 1) how much change in productivity or species composition may occur with near-future i...

  1. Studies of the airglow, the aurora, the ion and neutral composition, and the chemistry of the terrestrial atmosphere

    NASA Technical Reports Server (NTRS)

    Zipf, E. C., Jr.

    1974-01-01

    Results obtained by rocket-borne optical spectrometry are presented. Composition measurements and auroral studies are reported. The production of N (D-2) atoms by photo-absorption processes, and by electron impact excitation of N2 are discussed along with vibrationally excited CO2(+) ions in planetary atmospheres.

  2. Impacts of elevated atmospheric CO2 and O3 on forests: phytochemistry, trophic interactions, and ecosystem dynamics.

    PubMed

    Lindroth, Richard L

    2010-01-01

    Prominent among the many factors now affecting the sustainability of forest ecosystems are anthropogenically-generated carbon dioxide (CO2) and ozone (O3). CO2 is the substrate for photosynthesis and thus can accelerate tree growth, whereas O3 is a highly reactive oxygen species and interferes with basic physiological functions. This review summarizes the impacts of CO2 and O3 on tree chemical composition and highlights the consequences thereof for trophic interactions and ecosystem dynamics. CO2 and O3 influence phytochemical composition by altering substrate availability and biochemical/physiological processes such as photosynthesis and defense signaling pathways. Growth of trees under enriched CO2 generally leads to an increase in the C/N ratio, due to a decline in foliar nitrogen and concomitant increases in carbohydrates and phenolics. Terpenoid levels generally are not affected by atmospheric CO2 concentration. O3 triggers up-regulation of antioxidant defense pathways, leading to the production of simple phenolics and flavonoids (more so in angiosperms than gymnosperms). Tannins levels generally are unaffected, while terpenoids exhibit variable responses. In combination, CO2 and O3 exert both additive and interactive effects on tree chemical composition. CO2-and O3-mediated changes in plant chemistry influence host selection, individual performance (development, growth, reproduction), and population densities of herbivores (primarily phytophagous insects) and soil invertebrates. These changes can effect shifts in the amount and temporal pattern of forest canopy damage and organic substrate deposition. Decomposition rates of leaf litter produced under elevated CO2 and O3 may or may not be altered, and can respond to both the independent and interactive effects of the pollutants. Overall, however, CO2 and O3 effects on decomposition will be influenced more by their impacts on the quantity, rather than quality, of litter produced. A prominent theme to emerge

  3. Lichens as biomonitor of atmospheric aerosol composition in the Northwest European Russia

    NASA Astrophysics Data System (ADS)

    Shevchenko, Vladimir P.; Pokrovsky, Oleg S.; Zamber, Natalia S.; Konov, Konstantin G.; Starodymova, Dina P.

    2010-05-01

    Numerous studies have shown that aerosols are of importance for atmospheric chemistry and climate of the Arctic. At the coasts of Arctic seas and in their catchment areas delivery of chemical elements and compounds are registered in natural archives, for example in lichens. Lichens absorb substances, including trace elements, through dry and wet deposition, and have been widely used as biomonitors. We studied multi-element composition of terricolous (mostly of genera Cladonia and Cetraria) and fruticose epiphytic (mostly of genera Alectoria, Usnea and Bryoria) lichens collected in 2004-2009 in Kola Peninsula, Karelia, Arkhangelsk Region and Komi Republic of NW Russia, mostly in the frame of International Polar Year activity. About 110 samples were analyzed. The unwashed lichen samples were air dried and homogenised to a fine powder in an agate crusher. Samples were treated in a four-step chemical digestion procedure (full dissolution via acid attack) and element concentrations were determined by inductively coupled plasma-mass spectrometry (ICP-MS). Parts of dry samples were analyzed by instrumental neutron activation analysis (INAA). An enrichment factor (EF) was calculated for each element (X) relative to the composition of earth's crust: EF = ((X/Al) in lichen) / ((X/Al) in the earth's crust). Al was used as a crustal indicator. In most samples contents of Ti, V, Cr, Mn, Fe, Co, rare earth elements (REEs), Th, U are at the background level and their EFs are less than 10. These low EF values indicated that, relative to average values for crustal rocks, there was no enrichment of these elements in the lichen concerned. For some elements (Se, Cd, Zn, Sb, Pb, As, Ni, Cu) consistently higher EF values were obtained. These higher values were interpreted in terms of sources of both anthropogenic and natural sources other than crustal rock and (or) soil. These elements could be derived by long-range atmospheric transport. Highest concentrations of Cu, Ni, Pb in lichens

  4. The origin of particulate organic carbon in the marine atmosphere as indicated by its stable carbon isotopic composition

    NASA Astrophysics Data System (ADS)

    Chesselet, R.; Fontugne, M.; Buat-Ménard, P.; Ezat, U.; Lambert, C. E.

    1981-04-01

    Organic carbon concentration and isotopic composition were determined in samples of atmospheric particulate matter collected in 1979 at remote marine locations (Enewetak atoll, Sargasso Sea) during the SEAREX (Sea-Air Exchange) program field experiments. Atmospheric Particulate Organic Carbon (POC) concentrations were found to be in the range of 0.3 to 1.2µg.m-3, in agreement with previous literature data. The major mass of POC was found on the smallest particles (r<0.5µm). The 13C/12C of the small particles is close to the one expected (δ13C = 26 ± 2‰) for atmospheric POC of continental origin. For all the samples analysed so far, it appears that more than 80% of atmospheric POC over remote marine areas is of continental origin. This can be explained either by long-range transport of small sized continental organic aerosols or