Science.gov

Sample records for atmospheric chemistry project

  1. Integrated Global Observation Strategy - Ozone and Atmospheric Chemistry Project

    NASA Technical Reports Server (NTRS)

    Hilsenrath, Ernest; Readings, C. J.; Kaye, J.; Mohnen, V.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    The "Long Term Continuity of Stratospheric Ozone Measurements and Atmospheric Chemistry" project was one of six established by the Committee on Earth Observing Satellites (CEOS) in response to the Integrated Global Observing Strategy (IGOS) initiative. IGOS links satellite and ground based systems for global environmental observations. The strategy of this project is to develop a consensus of user requirements including the scientific (SPARC, IGAC, WCRP) and the applications community (WMO, UNEP) and to develop a long-term international plan for ozone and atmospheric chemistry measurements. The major components of the observing system include operational and research (meeting certain criteria) satellite platforms planned by the space faring nations which are integrated with a well supported and sustained ground, aircraft, and balloon measurements program for directed observations as well satellite validation. Highly integrated and continuous measurements of ozone, validation, and reanalysis efforts are essential to meet the international scientific and applications goals. In order to understand ozone trends, climate change, and air quality, it is essential to conduct long term measurements of certain other atmospheric species. These species include key source, radical, and reservoir constituents.

  2. Summary of completed project: 1991 Atmospheric Chemistry Gordon Research Conference

    SciTech Connect

    1995-04-01

    The focus of the Gordon Conference on Atmospheric Chemistry was to address and discuss several timely issues involving regional, continental and global scale chemical processes in both the troposphere and the stratosphere. These issues included photochemical pollution, tropospheric oxidative capacity, acid formation and deposition, greenhouse gas build-up, cloud and aerosol effects on chemical and radiation, biogeochemical cycling of trace atmospheric species and stratospheric ozone depletion. The technical sessions were organized along the topical lines used to define the US Global Tropospheric Chemistry Program with an added Policy and Perspective topic.

  3. Atmospheric chemistry

    SciTech Connect

    Sloane, C.S. ); Tesche, T.W. )

    1991-01-01

    This book covers the predictive strength of atmospheric models. The book covers all of the major important atmospheric areas, including large scale models for ozone depletion and global warming, regional scale models for urban smog (ozone and visibility impairment) and acid rain, as well as accompanying models of cloud processes and biofeedbacks.

  4. Compilation and analyses of emissions inventories for the NOAA atmospheric chemistry project. Progress report, August 1997

    SciTech Connect

    Benkovitz, C.M.

    1997-09-01

    Global inventories of anthropogenic emissions of oxides of nitrogen for circa 1985 and 1990 and non-methane volatile organic compounds (NMVOCs) for circa 1990 have been compiled by this project. Work on the inventories has been carried out under the umbrella of the Global Emissions Inventory Activity of the International Global Atmospheric Chemistry program. Global emissions of NOx for 1985 are estimated to be 21 Tg N/yr, with approximately 84% originating in the Northern Hemisphere. The global emissions for 1990 are 31 Tg N/yr for NOx and 173 Gg NMVOC/yr. Ongoing research activities for this project continue to address emissions of both NOx and NMVOCs. Future tasks include: evaluation of more detailed regional emissions estimates and update of the default 1990 inventories with the appropriate estimates; derivation of quantitative uncertainty estimates for the emission values; and development of emissions estimates for 1995.

  5. Atmospheric Chemistry and Greenhouse Gases

    SciTech Connect

    Ehhalt, D.; Prather, M.; Dentener, F.; Derwent, R.; Dlugokencky, Edward J.; Holland, E.; Isaksen, I.; Katima, J.; Kirchhoff, V.; Matson, P.; Midgley, P.; Wang, M.; Berntsen, T.; Bey, I.; Brasseur, G.; Buja, L.; Collins, W. J.; Daniel, J. S.; DeMore, W. B.; Derek, N.; Dickerson, R.; Etheridge, D.; Feichter, J.; Fraser, P.; Friedl, R.; Fuglestvedt, J.; Gauss, M.; Grenfell, L.; Grubler, Arnulf; Harris, N.; Hauglustaine, D.; Horowitz, L.; Jackman, C.; Jacob, D.; Jaegle, L.; Jain, Atul K.; Kanakidou, M.; Karlsdottir, S.; Ko, M.; Kurylo, M.; Lawrence, M.; Logan, J. A.; Manning, M.; Mauzerall, D.; McConnell, J.; Mickley, L. J.; Montzka, S.; Muller, J. F.; Olivier, J.; Pickering, K.; Pitari, G.; Roelofs, G.-J.; Rogers, H.; Rognerud, B.; Smith, Steven J.; Solomon, S.; Staehelin, J.; Steele, P.; Stevenson, D. S.; Sundet, J.; Thompson, A.; van Weele, M.; von Kuhlmann, R.; Wang, Y.; Weisenstein, D. K.; Wigley, T. M.; Wild, O.; Wuebbles, D.J.; Yantosca, R.; Joos, Fortunat; McFarland, M.

    2001-10-01

    Chapter 4 of the IPCC Third Assessment Report Climate Change 2001: The Scientific Basis. Sections include: Executive Summary 2414.1 Introduction 2434.2 Trace Gases: Current Observations, Trends and Budgets 2484.3 Projections of Future Emissions 2664.4 Projections of Atmospheric Composition for the 21st Century 2674.5 Open Questions 2774.6 Overall Impact of Global Atmospheric Chemistry Change 279

  6. Biomass burning studies and the International Global Atmospheric Chemistry (IGAC) project

    NASA Technical Reports Server (NTRS)

    Prinn, Ronald G.

    1991-01-01

    IGAC is an ambitious, decade-long and global research initiative concerned with major research challenges in the field of atmospheric chemistry; its chemists and ecosystem biologists are addressing the problems associated with global biomass burning (BMB). Among IGAC's goals is the achievement of a fundamental understanding of the natural and anthropogenic processes determining changes in atmospheric composition and chemistry, in order to allow century-long predictions. IGAC's studies have been organized into 'foci', encompassing the marine, tropical, polar, boreal, and midlatitude areas, as well as their global composite interactions. Attention is to be given to the effects of BMB on biogeochemical cycles.

  7. Introduction to Atmospheric Chemistry

    NASA Astrophysics Data System (ADS)

    Thompson, Anne M.

    In thirty years of university teaching, Peter Hobbs of the Atmospheric Sciences Department at the University of Washington, has seen atmospheric chemistry grow from a relatively small branch of geosciences into one with which every student of atmospheric sciences needs familiarity Some students are captivated in their first course and make atmospheric chemistry a field of further study or a lifelong career. At the same time, courses of “global change” and emerging curricula in scientific policy require students from diverse backgrounds to develop sufficient knowledge to become well-informed policy-makers. A number of practicing atmospheric chemists are retrained on the job from other scientific backgrounds and need selfeducation in the basics of the field.

  8. (Chemistry of the global atmosphere)

    SciTech Connect

    Marland, G.

    1990-09-27

    The traveler attended the conference The Chemistry of the Global Atmosphere,'' and presented a paper on the anthropogenic emission of carbon dioxide (CO{sub 2}) to the atmosphere. The conference included meetings of the International Global Atmospheric Chemistry (IGAC) programme, a core project of the International Geosphere/Biosphere Programme (IGBP) and the traveler participated in meetings on the IGAC project Development of Global Emissions Inventories'' and agreed to coordinate the working group on CO{sub 2}. Papers presented at the conference focused on the latest developments in analytical methods, modeling and understanding of atmospheric CO{sub 2}, CO, CH{sub 4}, N{sub 2}O, SO{sub 2}, NO{sub x}, NMHCs, CFCs, and aerosols.

  9. Heterogeneous atmospheric chemistry

    NASA Technical Reports Server (NTRS)

    Schryer, D. R.

    1982-01-01

    The present conference on heterogeneous atmospheric chemistry considers such topics concerning clusters, particles and microparticles as common problems in nucleation and growth, chemical kinetics, and catalysis, chemical reactions with aerosols, electron beam studies of natural and anthropogenic microparticles, and structural studies employing molecular beam techniques, as well as such gas-solid interaction topics as photoassisted reactions, catalyzed photolysis, and heterogeneous catalysis. Also discussed are sulfur dioxide absorption, oxidation, and oxidation inhibition in falling drops, sulfur dioxide/water equilibria, the evidence for heterogeneous catalysis in the atmosphere, the importance of heterogeneous processes to tropospheric chemistry, soot-catalyzed atmospheric reactions, and the concentrations and mechanisms of formation of sulfate in the atmospheric boundary layer.

  10. Atmospheric Chemistry Data Products

    NASA Technical Reports Server (NTRS)

    2003-01-01

    This presentation poster covers data products from the Distributed Active Archive Center (DAAC) of the Goddard Earth Sciences (GES) Data and Information Services Center (DISC). Total Ozone Mapping Spectrometer products (TOMS) introduced in the presentation include TOMS Version 8 as well as Aura, which provides 25 years of TOMS and Upper Atmosphere Research Satellite (UARS) data. The presentation lists a number of atmospheric chemistry and dynamics data sets at DAAC.

  11. Atmospheric chemistry research

    SciTech Connect

    Saylor, R.D. )

    1990-01-01

    Global environmental changes are occurring all around us, and the energy industry is a major player in the changes that are taking place. Wise energy policy can only be generated from a position of informed enlightenment and understanding about the environmental consequences of energy production and utilization. The atmospheric chemistry research being conducted at the University of Kentucky's Center for Applied Energy Research is geared toward providing the knowledge necessary to allow industrial and legislative officials to make responsible energy decisions in the 1990's and beyond. Three programs are described: the Kentucky Acid Deposition Program Precipitation chemistry network; modeling of regional and urban photochemistry and acid deposition; and modeling of global tropospheric chemistry.

  12. COMPILATION AND ANALYSES OF EMISSIONS INVENTORIES FOR THE NOAA ATMOSPHERIC CHEMISTRY PROJECT. PROGRESS REPORT, AUGUST 1997.

    SciTech Connect

    BENKOVITZ,C.M.

    1997-09-01

    Global inventories of anthropogenic emissions of oxides of nitrogen (NO{sub x}) for circa 1985 and 1990 and Non-Methane Volatile Organic Compounds (NMVOCs) for circa 1990 have been compiled by this project. Work on the inventories has been carried out under the umbrella of the Global Emissions Inventory Activity (GEIA) of the International Global Atmospheric Chemistry (IGAC) Program. The 1985 NO{sub x} inventory was compiled using default data sets of global emissions that were refined via the use of more detailed regional data sets; this inventory is being distributed to the scientific community at large as the GEIA Version 1A inventory. Global emissions of NO{sub x} for 1985 are estimated to be 21 Tg N y{sup -1}, with approximately 84% originating in the Northern Hemisphere. The 1990 inventories of NO{sub x} and NMVOCs were compiled using unified methodologies and data sets in collaboration with the Netherlands National Institute of Public Health and Environmental Protection (Rijksinstituut Voor Volksgezondheid en Milieuhygiene, RIVM) and the Division of Technology for Society of the Netherlands Organization for Applied Scientific Research, (IMW-TNO); these emissions will be used as the default estimates to be updated with more accurate regional data. The NMVOC inventory was gridded and speciated into 23 chemical categories. The resulting global emissions for 1990 are 31 Tg N yr{sup -1} for NO{sub x} and 173 Gg NMVOC yr{sup -1}. Emissions of NO{sub x} are highest in the populated and industrialized areas of eastern North America and across Europe, and in biomass burning areas of South America, Africa, and Asia. Emissions of NMVOCs are highest in biomass burning areas of South America, Africa, and Asia. The 1990 NO{sub x} emissions were gridded to 1{sup o} resolution using surrogate data, and were given seasonal, two-vertical-level resolution and speciated into NO and NO{sub 2} based on proportions derived from the 1985 GEIA Version 1B inventory. Global NMVOC

  13. Atmospheric Pseudohalogen Chemistry

    NASA Technical Reports Server (NTRS)

    Lary, David John

    2004-01-01

    Hydrogen cyanide is not usually considered in atmospheric chemical models. The paper presents three reasons why hydrogen cyanide is likely to be significant for atmospheric chemistry. Firstly, HCN is a product and marker of biomass burning. Secondly, it is also likely that lightning is producing HCN, and as HCN is sparingly soluble it could be a useful long-lived "smoking gun" marker of lightning activity. Thirdly, the chemical decomposition of HCN leads to the production of small amounts of the cyanide (CN) and NCO radicals. The NCO radical can be photolyzed in the visible portion of the spectrum yielding nitrogen atoms (N). The production of nitrogen atoms is significant as it leads to the titration of total nitrogen from the atmosphere via N+N->N2, where N2 is molecular nitrogen.

  14. Venus Middle Atmosphere Chemistry

    NASA Astrophysics Data System (ADS)

    Mills, F. P.; Sundaram, M.; Slanger, T. G.; Allen, M.; Yung, Y. L.

    2005-08-01

    Venus is the most similar planet to Earth, and years of research have sought to understand their similarities and differences. Yet, it is still not clear what chemical processes maintain the long-term stability of Venus' primarily CO2 atmosphere. CO2 dissociates into CO and O after absorbing photons at wavelengths < 210 nm. These O atoms should combine to form O2, and observations of intense airglow confirm rapid production of O2 on both day and night sides. CO and O2 are sufficiently stable that an initially pure CO2 atmosphere would rapidly evolve to have 7-8% CO and 3.5-4% O2 [1]. The observed upper limit on O2 (0.3 ppm [2]), however, indicates catalytic mechanisms [3], rapidly convert CO and oxygen into CO2. The current understanding of Venus middle atmosphere chemistry, the state of lab data, and prospects for advances based on Venus Express will be reviewed. Recent work evaluating newly proposed mechanisms for producing CO2, which could be important depending on the rates of poorly constrained reactions, will be described. This research was supported by funding from NASA's Planetary Atmospheres program and the Australian Research Council. Part of this work was carried out by the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. [1] Nair, et al., Icarus 111, 124 (1994), [2] Trauger and Lunine, Icarus 55, 272 (1983), [3] Pernice, et al., PNAS 101, 14007 (2004)

  15. Partial support for the International Global Atmospheric Chemistry Core Project Office

    SciTech Connect

    Prinn, Ronald G.

    2001-05-04

    IGAC provides an international framework for the planning, coordination, and execution of atmospheric--biospheric research with emphasis on projects which require resources beyond the capabilities of any single nation. The development of chemical emission inventories by IGAC scientists, the development and intercomparison under IGAC leadership of existing chemical transport models, the analysis of data gathered during IGAC-sponsored field campaigns, etc., has provided new scientific information essential to the development of the discipline.

  16. The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP): Overview and Description of Models, Simulations and Climate Diagnostics

    SciTech Connect

    Lamarque, J.-F.; Shindell, Drew; Josse, B.; Young, P. J.; Cionni, I.; Eyring, Veronika; Bergmann, D.; Cameron-Smith, Philip; Collins, W. J.; Doherty, R.; Dalsoren, S.; Faluvegi, G.; Folberth, G.; Ghan, Steven J.; Horowitz, L.; Lee, Y. H.; MacKenzie, I. A.; Nagashima, T.; Naik, Vaishali; Plummer, David; Righi, M.; Rumbold, S.; Schulz, M.; Skeie, R. B.; Stevenson, D. S.; Strode, S.; Sudo, K.; Szopa, S.; Voulgarakis, A.; Zeng, G.

    2013-02-07

    The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) consists of a series of timeslice experiments targeting the long-term changes in atmospheric composition between 1850 and 2100, with the goal of documenting radiative forcing and the associated composition changes. Here we introduce the various simulations performed under ACCMIP and the associated model output. The ACCMIP models have a wide range of horizontal and vertical resolutions, vertical extent, chemistry schemes and interaction with radiation and clouds. While anthropogenic and biomass burning emissions were specified for all time slices in the ACCMIP protocol, it is found that the natural emissions lead to a significant range in emissions, mostly for ozone precursors. The analysis of selected present-day climate diagnostics (precipitation, temperature, specific humidity and zonal wind) reveals biases consistent with state-of-the-art climate models. The model-to-model comparison of changes in temperature, specific humidity and zonal wind between 1850 and 2000 and between 2000 and 2100 indicates mostly consistent results, but with outliers different enough to possibly affect their representation of climate impact on chemistry.

  17. The chemistry of planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Huntress, W. T., Jr.

    1976-01-01

    Present knowledge concerning the chemistry of planetary atmospheres is reviewed along with the theories which attempt to explain observational data. The known gross atmospheric compositions of the terrestrial and giant planets are listed, differences between the atmospheres of earth and Venus are discussed, and the atmospheres of the giant planets are described. The origin and evolution of the atmospheres of earth, Venus, Mars, Jupiter, Saturn, and Uranus are outlined, and chemical processes in the atmospheres are examined, particularly cloud formation. The question of organic synthesis and evolution in the reducing atmospheres of the giant planets is considered. It is noted that laboratory work on the individual chemical processes and reactions involved in the evolution of organic compounds in planetary atmospheres, comets, and interstellar space points to the inevitability of organic-compound synthesis in all these situations and to the pervasiveness of organic chemistry throughout the universe.

  18. Evaluation of Present-day Aerosols over China Simulated from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

    NASA Astrophysics Data System (ADS)

    Liao, H.; Chang, W.

    2014-12-01

    High concentrations of aerosols over China lead to strong radiative forcing that is important for both regional and global climate. To understand the representation of aerosols in China in current global climate models, we evaluate extensively the simulated present-day aerosol concentrations and aerosol optical depth (AOD) over China from the 12 models that participated in Atmospheric Chemistry & Climate Model Intercomparison Project (ACCMIP), by using ground-based measurements and satellite remote sensing. Ground-based measurements of aerosol concentrations used in this work include those from the China Meteorological Administration (CMA) Atmosphere Watch Network (CAWNET) and the observed fine-mode aerosol concentrations collected from the literature. The ground-based measurements of AOD in China are taken from the AErosol RObotic NETwork (AERONET), the sites with CIMEL sun photometer operated by Institute of Atmospheric Physics, Chinese Academy of Sciences, and from Chinese Sun Hazemeter Network (CSHNET). We find that the ACCMIP models generally underestimate concentrations of all major aerosol species in China. On an annual mean basis, the multi-model mean concentrations of sulfate, nitrate, ammonium, black carbon, and organic carbon are underestimated by 63%, 73%, 54%, 53%, and 59%, respectively. The multi-model mean AOD values show low biases of 20-40% at studied sites in China. The ACCMIP models can reproduce seasonal variation of nitrate but cannot capture well the seasonal variations of other aerosol species. Our analyses indicate that current global models generally underestimate the role of aerosols in China in climate simulations.

  19. Study of the atmospheric chemistry of radon progeny in laboratory and real indoor atmospheres. Final project report

    SciTech Connect

    Hopke, P.K.

    1996-09-01

    This report completes Clarkson University`s study of the chemical and physical behavior of the {sup 218}Po atom immediately following its formation by the alpha decay of radon. Because small changes in size for activity in the sub-10 nm size range result in large changes in the delivered dose per unit exposure, this behavior must be understood if the exposure to radon progeny and it dose to the cells in the respiratory tract are to be fully assessed. In order to pursue this general goal, two areas of radon progeny behavior are being pursued; laboratory studies under controlled conditions to better understand the fundamental physical and chemical processes that affect the progeny`s atmospheric behavior and studies in actual indoor environments to develop a better assessment of the exposure of the occupants of that space to the size and concentration of the indoor radioactive aerosol. Thus, two sets of specific goals have been established for this project. The specific tasks of the controlled laboratory studies are (1) Determine the formation rates of {circ}OH radicals formed by the radiolysis of air following radon decay; (2) Examine the formation of particles by the radiolytic oxidation of substances like SO{sub 2}, ethylene, and H{sub 2}S to lower vapor pressure compounds and determine the role of gas phase additives such as H{sub 2}O and NH{sub 3} in determining the particle size; (3) Measure the rate of ion-induced nucleation using a thermal diffusion cloud chamber, and (4) Measure the neutralization rate of {sup 218}PoO{sub x}{sup +} in O{sub 2} at low radon concentrations.

  20. Tropospheric ozone changes, radiative forcing and attribution to emissions in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

    NASA Astrophysics Data System (ADS)

    Stevenson, D. S.; Young, P. J.; Naik, V.; Lamarque, J.-F.; Shindell, D. T.; Voulgarakis, A.; Skeie, R. B.; Dalsoren, S. B.; Myhre, G.; Berntsen, T. K.; Folberth, G. A.; Rumbold, S. T.; Collins, W. J.; MacKenzie, I. A.; Doherty, R. M.; Zeng, G.; van Noije, T. P. C.; Strunk, A.; Bergmann, D.; Cameron-Smith, P.; Plummer, D. A.; Strode, S. A.; Horowitz, L.; Lee, Y. H.; Szopa, S.; Sudo, K.; Nagashima, T.; Josse, B.; Cionni, I.; Righi, M.; Eyring, V.; Conley, A.; Bowman, K. W.; Wild, O.; Archibald, A.

    2013-03-01

    Ozone (O3) from 17 atmospheric chemistry models taking part in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) has been used to calculate tropospheric ozone radiative forcings (RFs). All models applied a common set of anthropogenic emissions, which are better constrained for the present-day than the past. Future anthropogenic emissions follow the four Representative Concentration Pathway (RCP) scenarios, which define a relatively narrow range of possible air pollution emissions. We calculate a value for the pre-industrial (1750) to present-day (2010) tropospheric ozone RF of 410 mW m-2. The model range of pre-industrial to present-day changes in O3 produces a spread (±1 standard deviation) in RFs of ±17%. Three different radiation schemes were used - we find differences in RFs between schemes (for the same ozone fields) of ±10%. Applying two different tropopause definitions gives differences in RFs of ±3%. Given additional (unquantified) uncertainties associated with emissions, climate-chemistry interactions and land-use change, we estimate an overall uncertainty of ±30% for the tropospheric ozone RF. Experiments carried out by a subset of six models attribute tropospheric ozone RF to increased emissions of methane (44±12%), nitrogen oxides (31 ± 9%), carbon monoxide (15 ± 3%) and non-methane volatile organic compounds (9 ± 2%); earlier studies attributed more of the tropospheric ozone RF to methane and less to nitrogen oxides. Normalising RFs to changes in tropospheric column ozone, we find a global mean normalised RF of 42 mW m-2 DU-1, a value similar to previous work. Using normalised RFs and future tropospheric column ozone projections we calculate future tropospheric ozone RFs (mW m-2; relative to 1750) for the four future scenarios (RCP2.6, RCP4.5, RCP6.0 and RCP8.5) of 350, 420, 370 and 460 (in 2030), and 200, 300, 280 and 600 (in 2100). Models show some coherent responses of ozone to climate change: decreases in the

  1. Tropospheric Ozone Changes, Radiative Forcing and Attribution to Emissions in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

    NASA Technical Reports Server (NTRS)

    Stevenson, D.S.; Young, P.J.; Naik, V.; Lamarque, J.-F.; Shindell, D. T.; Voulgarakis, A.; Skeie, R. B.; Dalsoren, S. B.; Myhre, G.; Berntsen, T. K.; Folberth, G. A.; Rumbold, S. T.; Collins, W. J.; MacKenzie, I. A.; Doherty, R. M.; Zeng, G.; vanNoije, T. P. C.; Strunk, A.; Bergmann, D.; Cameron-Smith, P.; Plummer, D. A.; Strode, S. A.; Horowitz, L.; Lee, Y. H.; Szopa, S.; Sudo, K.; Nagashima, T.; Josse, B.; Cionni, I.; Righi, M.; Eyring, V.; Conley, A.; Bowman, K. W.; Wild, O.; Archibald, A.

    2013-01-01

    Ozone (O3) from 17 atmospheric chemistry models taking part in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) has been used to calculate tropospheric ozone radiative forcings (RFs). All models applied a common set of anthropogenic emissions, which are better constrained for the present-day than the past. Future anthropogenic emissions follow the four Representative Concentration Pathway (RCP) scenarios, which define a relatively narrow range of possible air pollution emissions. We calculate a value for the pre-industrial (1750) to present-day (2010) tropospheric ozone RF of 410 mW m-2. The model range of pre-industrial to present-day changes in O3 produces a spread (+/-1 standard deviation) in RFs of +/-17%. Three different radiation schemes were used - we find differences in RFs between schemes (for the same ozone fields) of +/-10 percent. Applying two different tropopause definitions gives differences in RFs of +/-3 percent. Given additional (unquantified) uncertainties associated with emissions, climate-chemistry interactions and land-use change, we estimate an overall uncertainty of +/-30 percent for the tropospheric ozone RF. Experiments carried out by a subset of six models attribute tropospheric ozone RF to increased emissions of methane (44+/-12 percent), nitrogen oxides (31 +/- 9 percent), carbon monoxide (15 +/- 3 percent) and non-methane volatile organic compounds (9 +/- 2 percent); earlier studies attributed more of the tropospheric ozone RF to methane and less to nitrogen oxides. Normalising RFs to changes in tropospheric column ozone, we find a global mean normalised RF of 42 mW m(-2) DU(-1), a value similar to previous work. Using normalised RFs and future tropospheric column ozone projections we calculate future tropospheric ozone RFs (mW m(-2); relative to 1750) for the four future scenarios (RCP2.6, RCP4.5, RCP6.0 and RCP8.5) of 350, 420, 370 and 460 (in 2030), and 200, 300, 280 and 600 (in 2100). Models show some

  2. Organic chemistry in Titan's atmosphere

    NASA Technical Reports Server (NTRS)

    Scattergood, T.

    1982-01-01

    Laboratory photochemical simulations and other types of chemical simulations are discussed. The chemistry of methane, which is the major known constituent of Titan's atmosphere was examined with stress on what can be learned from photochemistry and particle irradiation. The composition of dust that comprises the haze layer was determined. Isotope fractionation in planetary atmospheres is also discussed.

  3. Heterogeneous Atmospheric Chemistry

    NASA Astrophysics Data System (ADS)

    Schryer, David R.

    In the past few years it has become increasingly clear that heterogeneous, or multiphase, processes play an important role in the atmosphere. Unfortunately the literature on the subject, although now fairly extensive, is still rather dispersed. Furthermore, much of the expertise regarding heterogeneous processes lies in fields not directly related to atmospheric science. Therefore, it seemed desirable to bring together for an exchange of ideas, information, and methodologies the various atmospheric scientists who are actively studying heterogeneous processes as well as other researchers studying similar processes in the context of other fields.

  4. Chemistry Of Atmospheric Brown Carbon

    SciTech Connect

    Laskin, Alexander; Laskin, Julia; Nizkorodov, Sergey

    2015-05-27

    Organic carbon (OC) accounts for a large fraction of atmospheric aerosol and has profound effects on air quality, atmospheric chemistry and climate forcing. Molecular composition of the OC and its evolution during common processes of atmospheric aging have been a subject of extensive research over the last decade (see reviews of Ervens et al.,1 Hallquist et al.,2 Herckes et al.,3 Carlton et al.,4 Kroll and Seinfeld,5 Rudich et al.,6 and Kanakidou et al.7). Even though many fundamental advances have been reported in these studies, our understanding of the climate-related properties of atmospheric OC is still incomplete and the specific ways in which OC impacts atmospheric environment and climate forcing are just beginning to be understood. This review covers one topic of particular interest in this area –environmental chemistry of light-absorbing aerosol OC and its impact on radiative forcing.

  5. Dynamical climatology of the NASA Langley Research Center Interactive Modeling Project for Atmospheric Chemistry and Transport (IMPACT) model

    NASA Astrophysics Data System (ADS)

    Pierce, R. Bradley; Al-Saadi, Jassim A.; Eckman, Richard S.; Fairlie, T. Duncan; Grose, William L.; Kleb, Mary M.; Natarajan, Murali; Olson, Jennifer R.

    2000-12-01

    A comparison of the NASA Langley Research Center (LaRC) Interactive Modeling Project for Atmospheric Chemistry and Transport (IMPACT) model's dynamical characteristics with assimilated data sets and observations is presented to demonstrate the ability of the model to represent the dynamical characteristics of Earth's troposphere and stratosphere. The LaRC IMPACT model is a coupled chemical/dynamical general circulation model (GCM) of the Earth's atmosphere extending from the surface to the lower mesosphere. It has been developed as a tool for assessing the effects of chemical, dynamical, and radiative coupling in the stratosphere on the Earth's climate. The LaRC IMPACT model winds and temperatures are found to be in fairly good agreement with Upper Atmospheric Research Satellite (UARS) United Kingdom Meteorological Office (UKMO) assimilated winds and temperatures in the lower stratosphere. The model upper stratospheric zonal mean temperatures are also in good agreement with the UARS-UKMO climatology except for a cold winter pole which results from the upward extension of the cold vortex temperatures and an elevated winter stratopause in the model. The cold pole bias is consistent with the overprediction of the winter stratospheric jet strength, and is characteristic of stratospheric GCMs in general. The model northern and southern hemisphere stratospheric eddy heat and momentum fluxes are within the expected interannual variability of the UARS-UKMO climatology. The combined effects of water vapor transport, radiative, convective, and planetary boundary layer parameterizations are shown to produce tropospheric winds and circulation statistics that are in good agreement with the UARS-UKMO climatology, although the model tropopause and upper tropospheric temperatures are generally cold relative to the UARS-UKMO temperatures. Comparisons between the model and UARS-UKMO climatology indicate that the model does a reasonable job in reproducing the frequency of observed

  6. Land cover change impacts on atmospheric chemistry: simulating projected large-scale tree mortality in the United States

    NASA Astrophysics Data System (ADS)

    Geddes, Jeffrey A.; Heald, Colette L.; Silva, Sam J.; Martin, Randall V.

    2016-02-01

    Land use and land cover changes impact climate and air quality by altering the exchange of trace gases between the Earth's surface and atmosphere. Large-scale tree mortality that is projected to occur across the United States as a result of insect and disease may therefore have unexplored consequences for tropospheric chemistry. We develop a land use module for the GEOS-Chem global chemical transport model to facilitate simulations involving changes to the land surface, and to improve consistency across land-atmosphere exchange processes. The model is used to test the impact of projected national-scale tree mortality risk through 2027 estimated by the 2012 USDA Forest Service National Insect and Disease Risk Assessment. Changes in biogenic emissions alone decrease monthly mean O3 by up to 0.4 ppb, but reductions in deposition velocity compensate or exceed the effects of emissions yielding a net increase in O3 of more than 1 ppb in some areas. The O3 response to the projected change in emissions is affected by the ratio of baseline NOx : VOC concentrations, suggesting that in addition to the degree of land cover change, tree mortality impacts depend on whether a region is NOx-limited or NOx-saturated. Consequently, air quality (as diagnosed by the number of days that 8 h average O3 exceeds 70 ppb) improves in polluted environments where changes in emissions are more important than changes to dry deposition, but worsens in clean environments where changes to dry deposition are the more important term. The influence of changes in dry deposition demonstrated here underscores the need to evaluate treatments of this physical process in models. Biogenic secondary organic aerosol loadings are significantly affected across the US, decreasing by 5-10 % across many regions, and by more than 25 % locally. Tree mortality could therefore impact background aerosol loadings by between 0.5 and 2 µg m-3. Changes to reactive nitrogen oxide abundance and partitioning are also locally

  7. Atmospheric chemistry over southern Africa

    NASA Astrophysics Data System (ADS)

    Gatebe, Charles K.; Levy, Robert C.; Thompson, Anne M.

    2012-03-01

    Changing Chemistry in a Changing Climate: Human and Natural Impacts Over Southern Africa (C4-SAR); Midrand, South Africa, 31 May to 3 June 2011 During the southern African dry season, regional haze from mixed industrial pollution, biomass burning aerosol and gases from domestic and grassland fires, and biogenic sources from plants and soils is worsened by a semipermanent atmospheric gyre over the subcontinent. These factors were a driver of several major international field campaigns in the 1990s and early 2000s and attracted many scientists to the region. Some researchers were interested in understanding fundamental processes governing chemistry of the atmosphere and interaction with climate change. Others found favorable conditions for evaluating satellite- derived measurements of atmospheric properties and a changing land surface. With that background in mind a workshop on atmospheric chemistry was held in South Africa. Sponsored by the International Commission on Atmospheric Chemistry and Global Pollution (ICACGP; http://www.icacgp.org/), the workshop received generous support from Eskom, the South African power utility; and the Climatology Research Group of the University of the Witwatersrand, Johannesburg, South Africa.

  8. Land cover change impacts on atmospheric chemistry: simulating projected large-scale tree mortality in the United States

    NASA Astrophysics Data System (ADS)

    Geddes, J. A.; Heald, C. L.; Silva, S. J.; Martin, R. V.

    2015-10-01

    Land use and land cover changes impact climate and air quality by altering the exchange of trace gases between the Earth's surface and atmosphere. Large-scale tree mortality that is projected to occur across the United States as a result of insect and disease may therefore have unexplored consequences for tropospheric chemistry. We develop a land use module for the GEOS-Chem global chemical transport model to facilitate simulations involving changes to the land surface, and to improve consistency across land-atmosphere exchange processes. The model is used to test the impact of projected national-scale tree mortality risk through 2027 estimated by the 2012 USDA Forest Service National Insect and Disease Risk Assessment. Changes in biogenic emissions alone decrease monthly mean O3 by up to 0.4 ppb, but reductions in deposition velocity compensate or exceed the effects of emissions yielding a net increase in O3 of more than 1 ppb in some areas. The O3 response to emissions is controlled by the ratio of baseline NOx : VOC concentrations, suggesting that in addition to the degree of land cover change, tree mortality impacts depend on whether a region is NOx-limited or NOx-saturated. Consequently, air quality (as diagnosed by the number of days that average 8 h O3 exceeds 65 ppb) improves in polluted environments where changes in emissions are more important than changes to dry deposition, but worsens in clean environments where changes to dry deposition are the more important term. Biogenic secondary organic aerosol loadings are significantly affected across the US, decreasing by 5-10 % across many regions, and by more than 25 % locally. Tree mortality could therefore impact background aerosol loadings by between 0.5 to 2 μg m-3. Changes to reactive nitrogen oxide abundance and partitioning are also locally important. These simulations suggest that changes in biosphere-atmosphere exchange must be considered when predicting future air quality and climate. We point to

  9. Compilation and analyses of emissions inventories for NOAA`s atmospheric chemistry project. Progress report, August 1997

    SciTech Connect

    Benkovitz, C.M.; Mubaraki, M.A.

    1997-09-01

    Global inventories of anthropogenic emissions of oxides of nitrogen (NO{sub x}) for circa 1985 and 1990 and Non-Methane Volatile Organic Compounds (NMVOCs) for circa 1990 have been compiled by this project. Work on the inventories has been carried out under the umbrella of the Global Emissions Inventory Activity (GEIA) of the International Global Atmospheric Chemistry (IGAC) Program. The 1985 NO{sub x} inventory was compiled using default data sets of global emissions that were refined via the use of more detailed regional data sets; this inventory is being distributed to the scientific community at large as the GEIA Version 1A inventory. Global emissions of NO{sub x} for 1985 are estimated to be 21 Tg N y{sup -1}, with approximately 84% originating in the Northern Hemisphere. The 1990 inventories of NO{sub x} and NMVOCs were compiled using unified methodologies and data sets in collaboration with the Netherlands National Institute of Public Health and Environmental Protection (Rijksinstituut Voor Volksgezondheid en Milieuhygiene, RIVM) and the Division of Technology for Society of the Netherlands Organization for Applied Scientific Research, (IMW-TNO); these emissions will be used as the default estimates to be updated with more accurate regional data. The NMVOC inventory was gridded and speciated into 23 chemical categories.

  10. Computational solution of atmospheric chemistry problems

    NASA Technical Reports Server (NTRS)

    Jafri, J.; Ake, R. L.

    1986-01-01

    Extensive studies were performed on problems of interest in atmospheric chemistry. In addition to several minor projects, four major projects were performed and described (theoretical studies of ground and low-lying excited states of ClO2; ground and excited state potential energy surfaces of the methyl peroxy radical; electronic states ot the FO radical; and theoretical studies S02 (H2O) (sub n)).

  11. Atmospheric Chemistry Over Southern Africa

    NASA Technical Reports Server (NTRS)

    Gatebe, Charles K.; Levy, Robert C.; Thompson, Anne M.

    2011-01-01

    During the southern African dry season, regional haze from mixed industrial pollution, biomass burning aerosol and gases from domestic and grassland fires, and biogenic sources from plants and soils is worsened by a semi-permanent atmosphere gyre over the subcontinent. These factors were a driver of several major international field campaigns in the 1990s and early 2000s, and attracted many scientists to the region. Some researchers were interested in understanding fundamental processes governing chemistry of the atmosphere and interaction with climate change. Others found favorable conditions for evaluating satellite-derived measurements of atmospheric properties and a changing land surface. With that background in mind a workshop on atmospheric chemistry was held in South Africa. Sponsored by the International Commission for Atmospheric Chemistry and Global Pollution (ICACGP; http://www.icacgp.org/), the workshop received generous support from the South African power utility, Eskom, and the Climatology Research Group of the University of the Witwatersrand, Johannesburg, South Africa. The purpose of the workshop was to review some earlier findings as well as more recent findings on southern African climate vulnerability, chemical changes due to urbanization, land-use modification, and how these factors interact. Originally proposed by John Burrows, president of ICACGP, the workshop was the first ICACGP regional workshop to study the interaction of air pollution with global chemical and climate change. Organized locally by the University of the Witwatersrand, the workshop attracted more than 60 delegates from South Africa, Mozambique, Botswana, Zimbabwe, France, Germany, Canada, and the United States. More than 30 presentations were given, exploring both retrospective and prospective aspects of the science. In several talks, attention was focused on southern African chemistry, atmospheric pollution monitoring, and climate processes as they were studied in the field

  12. Atmospheric Chemistry and Air Pollution

    DOE PAGESBeta

    Gaffney, Jeffrey S.; Marley, Nancy A.

    2003-01-01

    Atmospheric chemistry is an important discipline for understanding air pollution and its impacts. This mini-review gives a brief history of air pollution and presents an overview of some of the basic photochemistry involved in the production of ozone and other oxidants in the atmosphere. Urban air quality issues are reviewed with a specific focus on ozone and other oxidants, primary and secondary aerosols, alternative fuels, and the potential for chlorine releases to amplify oxidant chemistry in industrial areas. Regional air pollution issues such as acid rain, long-range transport of aerosols and visibility loss, and the connections of aerosols to ozonemore » and peroxyacetyl nitrate chemistry are examined. Finally, the potential impacts of air pollutants on the global-scale radiative balances of gases and aerosols are discussed briefly.« less

  13. Multi-model Mean Nitrogen and Sulfur Deposition from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP): Evaluation Historical and Projected Changes

    NASA Technical Reports Server (NTRS)

    Lamarque, J.-F.; Dentener, F.; McConnell, J.; Ro, C.-U.; Shaw, M.; Vet, R.; Bergmann, D.; Cameron-Smith, P.; Doherty, R.; Faluvegi, G.; Ghan, S. J.; Josse, B.; Lee, Y. H.; MacKenzie, I. A.; Plummer, D.; Shindell, D. T.; Stevenson, D. S.; Strode, S.; Zeng, G.

    2013-01-01

    We present multi-model global datasets of nitrogen and sulfate deposition covering time periods from 1850 to 2100, calculated within the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP). The computed deposition fluxes are compared to surface wet deposition and ice-core measurements. We use a new dataset of wet deposition for 2000-2002 based on critical assessment of the quality of existing regional network data. We show that for present-day (year 2000 ACCMIP time-slice), the ACCMIP results perform similarly to previously published multi-model assessments. For this time slice, we find a multi-model mean deposition of 50 Tg(N) yr1 from nitrogen oxide emissions, 60 Tg(N) yr1 from ammonia emissions, and 83 Tg(S) yr1 from sulfur emissions. The analysis of changes between 1980 and 2000 indicates significant differences between model and measurements over the United States but less so over Europe. This difference points towards misrepresentation of 1980 NH3 emissions over North America. Based on ice-core records, the 1850 deposition fluxes agree well with Greenland ice cores but the change between 1850 and 2000 seems to be overestimated in the Northern Hemisphere for both nitrogen and sulfur species. Using the Representative Concentration Pathways to define the projected climate and atmospheric chemistry related emissions and concentrations, we find large regional nitrogen deposition increases in 2100 in Latin America, Africa and parts of Asia under some of the scenarios considered. Increases in South Asia are especially large, and are seen in all scenarios, with 2100 values more than double 2000 in some scenarios and reaching 1300 mg(N) m2 yr1 averaged over regional to continental scale regions in RCP 2.6 and 8.5, 3050 larger than the values in any region currently (2000). The new ACCMIP deposition dataset provides novel, consistent and evaluated global gridded deposition fields for use in a wide range of climate and ecological studies.

  14. Multi-model Mean Nitrogen and Sulfur Deposition from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP): Evaluation of Historical and Projected Future Changes

    SciTech Connect

    Lamarque, Jean-Francois; Dentener, Frank; McConnell, J.R.; Ro, C-U; Shaw, Mark; Vet, Robert; Bergmann, D.; Cameron-Smith, Philip; Dalsoren, S.; Doherty, R.; Faluvegi, G.; Ghan, Steven J.; Josse, B.; Lee, Y. H.; MacKenzie, I. A.; Plummer, David; Shindell, Drew; Skeie, R. B.; Stevenson, D. S.; Strode, S.; Zeng, G.; Curran, M.; Dahl-Jensen, D.; Das, S.; Fritzsche, D.; Nolan, M.

    2013-08-20

    We present multi-model global datasets of nitrogen and sulfate deposition covering time periods from 1850 to 2100, calculated within the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP). The computed deposition fluxes are compared to surface wet deposition and ice-core measurements. We use a new dataset of wet deposition for 2000-2002 based on critical assessment of the quality of existing regional network data. We show that for present-day (year 2000 ACCMIP time-slice), the ACCMIP results perform similarly to previously published multi-model assessments. The analysis of changes between 1980 and 2000 indicates significant differences between model and measurements over the United States, but less so over Europe. This difference points towards misrepresentation of 1980 NH3 emissions over North America. Based on ice-core records, the 1850 deposition fluxes agree well with Greenland ice cores but the change between 1850 and 2000 seems to be overestimated in the Northern Hemisphere for both nitrogen and sulfur species. Using the Representative Concentration Pathways to define the projected climate and atmospheric chemistry related emissions and concentrations, we find large regional nitrogen deposition increases in 2100 in Latin America, Africa and parts of Asia under some of the scenarios considered. Increases in South Asia are especially large, and are seen in all scenarios, with 2100 values more than double 2000 in some scenarios and reaching >1300 mgN/m2/yr averaged over regional to continental scale regions in RCP 2.6 and 8.5, ~30-50% larger than the values in any region currently (2000). Despite known issues, the new ACCMIP deposition dataset provides novel, consistent and evaluated global gridded deposition fields for use in a wide range of climate and ecological studies.

  15. Atmospheric chemistry in volcanic plumes.

    PubMed

    von Glasow, Roland

    2010-04-13

    Recent field observations have shown that the atmospheric plumes of quiescently degassing volcanoes are chemically very active, pointing to the role of chemical cycles involving halogen species and heterogeneous reactions on aerosol particles that have previously been unexplored for this type of volcanic plumes. Key features of these measurements can be reproduced by numerical models such as the one employed in this study. The model shows sustained high levels of reactive bromine in the plume, leading to extensive ozone destruction, that, depending on plume dispersal, can be maintained for several days. The very high concentrations of sulfur dioxide in the volcanic plume reduces the lifetime of the OH radical drastically, so that it is virtually absent in the volcanic plume. This would imply an increased lifetime of methane in volcanic plumes, unless reactive chlorine chemistry in the plume is strong enough to offset the lack of OH chemistry. A further effect of bromine chemistry in addition to ozone destruction shown by the model studies presented here, is the oxidation of mercury. This relates to mercury that has been coemitted with bromine from the volcano but also to background atmospheric mercury. The rapid oxidation of mercury implies a drastically reduced atmospheric lifetime of mercury so that the contribution of volcanic mercury to the atmospheric background might be less than previously thought. However, the implications, especially health and environmental effects due to deposition, might be substantial and warrant further studies, especially field measurements to test this hypothesis. PMID:20368458

  16. Atmospheric chemistry in volcanic plumes

    PubMed Central

    von Glasow, Roland

    2010-01-01

    Recent field observations have shown that the atmospheric plumes of quiescently degassing volcanoes are chemically very active, pointing to the role of chemical cycles involving halogen species and heterogeneous reactions on aerosol particles that have previously been unexplored for this type of volcanic plumes. Key features of these measurements can be reproduced by numerical models such as the one employed in this study. The model shows sustained high levels of reactive bromine in the plume, leading to extensive ozone destruction, that, depending on plume dispersal, can be maintained for several days. The very high concentrations of sulfur dioxide in the volcanic plume reduces the lifetime of the OH radical drastically, so that it is virtually absent in the volcanic plume. This would imply an increased lifetime of methane in volcanic plumes, unless reactive chlorine chemistry in the plume is strong enough to offset the lack of OH chemistry. A further effect of bromine chemistry in addition to ozone destruction shown by the model studies presented here, is the oxidation of mercury. This relates to mercury that has been coemitted with bromine from the volcano but also to background atmospheric mercury. The rapid oxidation of mercury implies a drastically reduced atmospheric lifetime of mercury so that the contribution of volcanic mercury to the atmospheric background might be less than previously thought. However, the implications, especially health and environmental effects due to deposition, might be substantial and warrant further studies, especially field measurements to test this hypothesis. PMID:20368458

  17. Coupling Processes between Atmospheric Chemistry and Climate

    NASA Technical Reports Server (NTRS)

    Ko, M. K. W.; Weisenstein, Debra; Shia, Run-Lie; Sze, N. D.

    1998-01-01

    This is the third semi-annual report for NAS5-97039, covering January through June 1998. The overall objective of this project is to improve the understanding of coupling processes between atmospheric chemistry and climate. Model predictions of the future distributions of trace gases in the atmosphere constitute an important component of the input necessary for quantitative assessments of global change. We will concentrate on the changes in ozone and stratospheric sulfate aerosol, with emphasis on how ozone in the lower stratosphere would respond to natural or anthropogenic changes. The key modeling for this work are the AER 2-dimensional chemistry-transport model, the AER 2-dimensional stratospheric sulfate model, and the AER three-wave interactive model with full chemistry. We will continue developing our three-wave model so that we can help NASA determine the strengths and weaknesses of the next generation assessment models.

  18. Coupling Processes Between Atmospheric Chemistry and Climate

    NASA Technical Reports Server (NTRS)

    Ko, Malcolm K. W.; Weisenstein, Debra; Shia, Run-Lie; Sze, N. D.

    1998-01-01

    The overall objective of this project is to improve the understanding of coupling processes between atmospheric chemistry and climate. Model predictions of the future distributions of trace gases in the atmosphere constitute an important component of the input necessary for quantitative assessments of global change. We will concentrate on the changes in ozone and stratospheric sulfate aerosol, with emphasis on how ozone in the lower stratosphere would respond to natural or anthropogenic changes. The key modeling tools for this work are the AER 2-dimensional chemistry-transport model, the AER 2-dimensional stratospheric sulfate model, and the AER three-wave interactive model with full chemistry. We will continue developing our three-wave model so that we can help NASA determine the strength and weakness of the next generation assessment models.

  19. Coupling Processes Between Atmospheric Chemistry and Climate

    NASA Technical Reports Server (NTRS)

    Ko, M. K. W.; Weisenstein, Debra; Shia, Run-Lie; Sze, N. D.

    1998-01-01

    The overall objective of this project is to improve the understanding of coupling processes between atmospheric chemistry and climate. Model predictions of the future distributions of trace gases in the atmosphere constitute an important component of the input necessary for quantitative assessments of global change. We will concentrate on the changes in ozone and stratospheric sulfate aerosol, with emphasis on how ozone in the lower stratosphere would respond to natural or anthropogenic changes. The key modeling tools for this work are the AER two-dimensional chemistry-transport model, the AER two-dimensional stratospheric sulfate model, and the AER three-wave interactive model with full chemistry. We will continue developing our three-wave model so that we can help NASA determine the strength and weakness of the next generation assessment models.

  20. 1997 Atmospheric Chemistry Colloquium for Emerging Senior Scientists

    SciTech Connect

    Paul H. Wine

    1998-11-23

    DOE's Atmospheric Chemistry Program is providing partial funding for the Atmospheric Chemistry Colloquium for Emerging Senior Scientists (ACCESS) and FY 1997 Gordon Research Conference in Atmospheric Chemistry

  1. Coupling Processes Between Atmospheric Chemistry and Climate

    NASA Technical Reports Server (NTRS)

    Ko, M. K. W.; Weisenstein, Debra; Shia, Run-Li; Sze, N. D.

    1997-01-01

    This is the first semi-annual report for NAS5-97039 summarizing work performed for January 1997 through June 1997. Work in this project is related to NAS1-20666, also funded by NASA ACMAP. The work funded in this project also benefits from work at AER associated with the AER three-dimensional isentropic transport model funded by NASA AEAP and the AER two-dimensional climate-chemistry model (co-funded by Department of Energy). The overall objective of this project is to improve the understanding of coupling processes between atmospheric chemistry and climate. Model predictions of the future distributions of trace gases in the atmosphere constitute an important component of the input necessary for quantitative assessments of global change. We will concentrate on the changes in ozone and stratospheric sulfate aerosol, with emphasis on how ozone in the lower stratosphere would respond to natural or anthropogenic changes. The key modeling tools for this work are the AER two-dimensional chemistry-transport model, the AER two-dimensional stratospheric sulfate model, and the AER three-wave interactive model with full chemistry.

  2. Global changes to atmospheric chemistry

    SciTech Connect

    Brasseur, G.P.; Holland, E.A.

    1995-06-01

    Changes in atmospheric concentrations of trace gases provided early evidence of widespread changes within the biosphere. Trace gas production by plants and in soils increased in response to human pressures. Long lived trace gases like nitrous oxide and methane are greenhouse gases and play an important role in stratospheric chemistry. Photochemically active compounds, isoprene, nitric oxide, and carbon monoxide, are determinants of tropospheric ozone concentrations and thus regulate the oxidizing capacity of the troposphere. Inclusion of isoprene produced by plants in 3-D chemical transport models increases atmospheric concentrations of ozone and carbon monoxide substantially. In return, terrestrial ecosystems are sensitive to atmospheric composition, responding to increased N deposition with increased C uptake, and soil acidification, and responding to increased ozone concentrations and UV-B with decreased plant production.

  3. Coupling Processes between Atmospheric Chemistry and Climate

    NASA Technical Reports Server (NTRS)

    Ko, Malcolm K. W.; Weisenstein, Debra K.; Shia, Run-Lie; Scott, Courtney J.; Sze, Nien Dak

    1998-01-01

    This is the fourth semi-annual report for NAS5-97039, covering the time period July through December 1998. The overall objective of this project is to improve the understanding of coupling processes between atmospheric chemistry and climate. Model predictions of the future distributions of trace gases in the atmosphere constitute an important component of the input necessary for quantitative assessments of global change. We will concentrate on the changes in ozone and stratospheric sulfate aerosol, with emphasis on how ozone in the lower stratosphere would respond to natural or anthropogenic changes. The key modeling tools for this work are the Atmospheric and Environmental Research (AER) two-dimensional chemistry-transport model, the AER two-dimensional stratospheric sulfate model, and the AER three-wave interactive model with full chemistry. For this six month period, we report on a modeling study of new rate constant which modify the NOx/NOy ratio in the lower stratosphere; sensitivity to changes in stratospheric water vapor in the future atmosphere; a study of N2O and CH4 observations which has allowed us to adjust diffusion in the 2-D CTM in order to obtain appropriate polar vortex isolation; a study of SF6 and age of air with comparisons of models and measurements; and a report on the Models and Measurements II effort.

  4. The chemistry of Venus' atmosphere

    NASA Technical Reports Server (NTRS)

    Sze, N. D.; Smith, W. H.

    1978-01-01

    A model for the Venus atmosphere involving photochemistry of oxygen, hydrogen, chlorine and sulfur species is presented. Sulfur reaction schemes and hydrogen and chlorine reaction schemes were included. The impact of sulfur on the oxygen budget and the subsequent production of H2SO4 molecules for the Venus cloud deck were explored. A major new reaction scheme for production of H2SO4 molecules involving sulfur and oxygen chemistry was established shown to dominate over the odd hydrogen scheme proposed earlier. The efficiency of the scheme in formation of H2SO4 is only about 50%, with the remaining sulfur residing in SO2 molecules. The calculated downward flux of H2SO4 may be sufficient to maintain a steady state sulfuric acid cloud if the resident time of H2SO4 droplets in the cloud is as long as a few years. If however, the resident time is half a year or shorter, additional chemistry capable of more efficient conversion of SO2 to SO3 is required.

  5. Frontiers in Atmospheric Chemistry Modelling

    NASA Astrophysics Data System (ADS)

    Colette, Augustin; Bessagnet, Bertrand; Meleux, Frederik; Rouïl, Laurence

    2013-04-01

    The first pan-European kilometre-scale atmospheric chemistry simulation is introduced. The continental-scale air pollution episode of January 2009 is modelled with the CHIMERE offline chemistry-transport model with a massive grid of 2 million horizontal points, performed on 2000 CPU of a high performance computing system hosted by the Research and Technology Computing Center at the French Alternative Energies and Atomic Energy Commission (CCRT/CEA). Besides the technical challenge, which demonstrated the robustness of the selected air quality model, we discuss the added value in terms of air pollution modelling and decision support. The comparison with in-situ observations shows that model biases are significantly improved despite some spurious added spatial variability attributed to shortcomings in the emission downscaling process and coarse resolution of the meteorological fields. The increased spatial resolution is clearly beneficial for the detection of exceedances and exposure modelling. We reveal small scale air pollution patterns that highlight the contribution of city plumes to background air pollution levels. Up to a factor 5 underestimation of the fraction of population exposed to detrimental levels of pollution can be obtained with a coarse simulation if subgrid scale correction such as urban increments are ignored. This experiment opens new perspectives for environmental decision making. After two decades of efforts to reduce air pollutant emissions across Europe, the challenge is now to find the optimal trade-off between national and local air quality management strategies. While the first approach is based on sectoral strategies and energy policies, the later builds upon new alternatives such as urban development. The strategies, the decision pathways and the involvement of individual citizen differ, and a compromise based on cost and efficiency must be found. We illustrated how high performance computing in atmospheric science can contribute to this

  6. 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

  7. Mars Atmospheric Chemistry and Astrobiology Workshop Summary

    NASA Astrophysics Data System (ADS)

    Allen, M.; Wennberg, P.

    2002-09-01

    The Mars Atmospheric Chemistry and Astrobiology (MACA) Workshop was held on the California Institute of Technology campus December 17-18, 2001. The prime objective of the workshop was to consider whether extant life beneath the surface, if it exists, would be in contact with the atmosphere and introduce a detectable signature in the atmosphere. To answer this question, the workshop also explored how well we understood the abiotic chemistry of the current atmosphere and other drivers of atmospheric composition (volcanoes, surface-atmosphere interactions, escape). The conclusions from this workshop will be presented.

  8. Pre-industrial to End 21st Century Projections of Tropospheric Ozone from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

    NASA Technical Reports Server (NTRS)

    Young, P. J.; Archibald, A. T.; Bowman, K. W.; Lamarque, J.-F.; Naik, V.; Stevenson, D. S.; Tilmes, S.; Voulgarakis, A.; Wild, O.; Bergmann, D.; Cameron-Smith, P.; Cionni, I.; Collins, W. J.; Dalsoren, S. B.; Doherty, R. M.; Eyring, V.; Faluvegi, G.; Horowitz, L. W.; Josse, B.; Lee, Y. H.; MacKenzie, I. A.; Nagashima, T.; Plummer, D. A.; Righi, M.; Strode, S. A.

    2013-01-01

    Present day tropospheric ozone and its changes between 1850 and 2100 are considered, analysing 15 global models that participated in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP). The ensemble mean compares well against present day observations. The seasonal cycle correlates well, except for some locations in the tropical upper troposphere. Most (75 %) of the models are encompassed with a range of global mean tropospheric ozone column estimates from satellite data, but there is a suggestion of a high bias in the Northern Hemisphere and a low bias in the Southern Hemisphere, which could indicate deficiencies with the ozone precursor emissions. Compared to the present day ensemble mean tropospheric ozone burden of 337+/-23 Tg, the ensemble mean burden for 1850 time slice is approx. 30% lower. Future changes were modelled using emissions and climate projections from four Representative Concentration Pathways (RCPs). Compared to 2000, the relative changes in the ensemble mean tropospheric ozone burden in 2030 (2100) for the different RCPs are: -4% (-16 %) for RCP2.6, 2% (-7%) for RCP4.5, 1% (-9%) for RCP6.0, and 7% (18 %) for RCP8.5. Model agreement on the magnitude of the change is greatest for larger changes. Reductions in most precursor emissions are common across the RCPs and drive ozone decreases in all but RCP8.5, where doubled methane and a 40-150% greater stratospheric influx (estimated from a subset of models) increase ozone. While models with a high ozone burden for the present day also have high ozone burdens for the other time slices, no model consistently predicts large or small ozone changes; i.e. the magnitudes of the burdens and burden changes do not appear to be related simply, and the models are sensitive to emissions and climate changes in different ways. Spatial patterns of ozone changes are well correlated across most models, but are notably different for models without time evolving stratospheric ozone concentrations

  9. Coupling Processes Between Atmospheric Chemistry and Climate

    NASA Technical Reports Server (NTRS)

    Ko, Malcolm K. W.; Weisenstein, Debra; Rodriguez, Jose; Danilin, Michael; Scott, Courtney; Shia, Run-Lie; Eluszkiewicz, Junusz; Sze, Nien-Dak

    1999-01-01

    This is the final report. The overall objective of this project is to improve the understanding of coupling processes among atmospheric chemistry, aerosol and climate, all important for quantitative assessments of global change. Among our priority are changes in ozone and stratospheric sulfate aerosol, with emphasis on how ozone in the lower stratosphere would respond to natural or anthropogenic changes. The work emphasizes two important aspects: (1) AER's continued participation in preparation of, and providing scientific input for, various scientific reports connected with assessment of stratospheric ozone and climate. These include participation in various model intercomparison exercises as well as preparation of national and international reports. and (2) Continued development of the AER three-wave interactive model to address how the transport circulation will change as ozone and the thermal properties of the atmosphere change, and assess how these new findings will affect our confidence in the ozone assessment results.

  10. Atmospheric Aerosol Chemistry Analyzer: Demonstration of feasibility

    SciTech Connect

    Mroz, E.J.; Olivares, J.; Kok, G.

    1996-04-01

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project objective was to demonstrate the technical feasibility of an Atmospheric Aerosol Chemistry Analyzer (AACA) that will provide a continuous, real-time analysis of the elemental (major, minor and trace) composition of atmospheric aerosols. The AACA concept is based on sampling the atmospheric aerosol through a wet cyclone scrubber that produces an aqueous suspension of the particles. This suspension can then be analyzed for elemental composition by ICP/MS or collected for subsequent analysis by other methods. The key technical challenge was to develop a wet cyclone aerosol sampler suitable for respirable particles found in ambient aerosols. We adapted an ultrasonic nebulizer to a conventional, commercially available, cyclone aerosol sampler and completed collection efficiency tests for the unit, which was shown to efficiently collect particles as small as 0.2 microns. We have completed the necessary basic research and have demonstrated the feasibility of the AACA concept.

  11. Collaborative Physical Chemistry Projects Involving Computational Chemistry

    NASA Astrophysics Data System (ADS)

    Whisnant, David M.; Howe, Jerry J.; Lever, Lisa S.

    2000-02-01

    The physical chemistry classes from three colleges have collaborated on two computational chemistry projects using Quantum CAChe 3.0 and Gaussian 94W running on Pentium II PCs. Online communication by email and the World Wide Web was an important part of the collaboration. In the first project, students used molecular modeling to predict benzene derivatives that might be possible hair dyes. They used PM3 and ZINDO calculations to predict the electronic spectra of the molecules and tested the predicted spectra by comparing some with experimental measurements. They also did literature searches for real hair dyes and possible health effects. In the final phase of the project they proposed a synthetic pathway for one compound. In the second project the students were asked to predict which isomer of a small carbon cluster (C3, C4, or C5) was responsible for a series of IR lines observed in the spectrum of a carbon star. After preliminary PM3 calculations, they used ab initio calculations at the HF/6-31G(d) and MP2/6-31G(d) level to model the molecules and predict their vibrational frequencies and rotational constants. A comparison of the predictions with the experimental spectra suggested that the linear isomer of the C5 molecule was responsible for the lines.

  12. Modeling the atmospheric chemistry of TICs

    NASA Astrophysics Data System (ADS)

    Henley, Michael V.; Burns, Douglas S.; Chynwat, Veeradej; Moore, William; Plitz, Angela; Rottmann, Shawn; Hearn, John

    2009-05-01

    An atmospheric chemistry model that describes the behavior and disposition of environmentally hazardous compounds discharged into the atmosphere was coupled with the transport and diffusion model, SCIPUFF. The atmospheric chemistry model was developed by reducing a detailed atmospheric chemistry mechanism to a simple empirical effective degradation rate term (keff) that is a function of important meteorological parameters such as solar flux, temperature, and cloud cover. Empirically derived keff functions that describe the degradation of target toxic industrial chemicals (TICs) were derived by statistically analyzing data generated from the detailed chemistry mechanism run over a wide range of (typical) atmospheric conditions. To assess and identify areas to improve the developed atmospheric chemistry model, sensitivity and uncertainty analyses were performed to (1) quantify the sensitivity of the model output (TIC concentrations) with respect to changes in the input parameters and (2) improve, where necessary, the quality of the input data based on sensitivity results. The model predictions were evaluated against experimental data. Chamber data were used to remove the complexities of dispersion in the atmosphere.

  13. Energy, atmospheric chemistry, and global climate

    NASA Technical Reports Server (NTRS)

    Levine, Joel S.

    1991-01-01

    Global atmospheric changes due to ozone destruction and the greenhouse effect are discussed. The work of the Intergovernmental Panel on Climate Change is reviewed, including its judgements regarding global warming and its recommendations for improving predictive capability. The chemistry of ozone destruction and the global atmospheric budget of nitrous oxide are reviewed, and the global sources of nitrous oxide are described.

  14. Tropospheric ozone changes, radiative forcing and attribution to emissions in the Atmospheric Chemistry and Climate Model Inter-comparison Project (ACCMIP)

    NASA Astrophysics Data System (ADS)

    Stevenson, D. S.; Young, P. J.; Naik, V.; Lamarque, J.-F.; Shindell, D. T.; Voulgarakis, A.; Skeie, R. B.; Dalsoren, S. B.; Myhre, G.; Berntsen, T. K.; Folberth, G. A.; Rumbold, S. T.; Collins, W. J.; MacKenzie, I. A.; Doherty, R. M.; Zeng, G.; van Noije, T. P. C.; Strunk, A.; Bergmann, D.; Cameron-Smith, P.; Plummer, D. A.; Strode, S. A.; Horowitz, L.; Lee, Y. H.; Szopa, S.; Sudo, K.; Nagashima, T.; Josse, B.; Cionni, I.; Righi, M.; Eyring, V.; Conley, A.; Bowman, K. W.; Wild, O.

    2012-10-01

    Ozone (O3) from 17 atmospheric chemistry models taking part in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) has been used to calculate tropospheric ozone radiative forcings (RFs). We calculate a~value for the pre-industrial (1750) to present-day (2010) tropospheric ozone RF of 0.40 W m-2. The model range of pre-industrial to present-day changes in O3 produces a spread (±1 standard deviation) in RFs of ±17%. Three different radiation schemes were used - we find differences in RFs between schemes (for the same ozone fields) of ±10%. Applying two different tropopause definitions gives differences in RFs of ±3%. Given additional (unquantified) uncertainties associated with emissions, climate-chemistry interactions and land-use change, we estimate an overall uncertainty of ±30% for the tropospheric ozone RF. Experiments carried out by a subset of six models attribute tropospheric ozone RF to increased emissions of methane (47%), nitrogen oxides (29%), carbon monoxide (15%) and non-methane volatile organic compounds (9%); earlier studies attributed more of the tropospheric ozone RF to methane and less to nitrogen oxides. Normalising RFs to changes in tropospheric column ozone, we find a global mean normalised RF of 0.042 W m-2 DU-1, a value similar to previous work. Using normalised RFs and future tropospheric column ozone projections we calculate future tropospheric ozone RFs (W m-2; relative to 1850 - add 0.04 W m-2 to make relative to 1750) for the Representative Concentration Pathways in 2030 (2100) of: RCP2.6: 0.31 (0.16); RCP4.5: 0.38 (0.26); RCP6.0: 0.33 (0.24); and RCP8.5: 0.42 (0.56). Models show some coherent responses of ozone to climate change: decreases in the tropical lower troposphere, associated with increases in water vapour; and increases in the sub-tropical to mid-latitude upper troposphere, associated with increases in lightning and stratosphere-to-troposphere transport.

  15. Information-computational system: atmospheric chemistry

    NASA Astrophysics Data System (ADS)

    Adamov, Dmitri P.; Akhlyostin, Alexey Y.; Fazliev, Alexandre Z.; Gordov, Eugeni P.; Karyakin, Alexey S.; Mikhailov, Sergey A.; Rodimova, Olga B.

    1999-11-01

    The atmospheric chemistry information-computational system (ICS) with Internet access is presented. The ICS is aimed summarizing fundamental data on atmospheric processes, determining the dynamics of complex chemical systems and providing educational information. The system consist of three functional blocks: data preparation, computation and information blocks, within which a user may choose the chemical reactions and atmospheric models, drive relevant kinetic equations and conservation laws, solve the kinetic equations, visualize the results of calculations and get access to related information.

  16. Atmospheric Chemistry: Nature's plasticized aerosols

    NASA Astrophysics Data System (ADS)

    Ziemann, Paul J.

    2016-01-01

    The structure of atmospheric aerosol particles affects their reactivity and growth rates. Measurements of aerosol properties over the Amazon rainforest indicate that organic particles above tropical rainforests are simple liquid drops.

  17. Coupling Processes Between Atmospheric Chemistry and Climate

    NASA Technical Reports Server (NTRS)

    Ko, Malcolm; Weisenstein, Debra; Rodriquez, Jose; Danilin, Michael; Scott, Courtney; Shia, Run-Lie; Eluszkiewicz, Janusz; Sze, Nien-Dak; Stewart, Richard W. (Technical Monitor)

    1999-01-01

    This is the final report for NAS5-97039 for work performed between December 1996 and November 1999. The overall objective of this project is to improve the understanding of coupling processes among atmospheric chemistry, aerosol and climate, all important for quantitative assessments of global change. Among our priority are changes in ozone and stratospheric sulfate aerosol, with emphasis on how ozone in the lower stratosphere would respond to natural or anthropogenic changes. The work emphasizes two important aspects: (1) AER's continued participation in preparation of, and providing scientific input for, various scientific reports connected with assessment of stratospheric ozone and climate. These include participation in various model intercomparison exercises as well as preparation of national and international reports. (2) Continued development of the AER three-wave interactive model to address how the transport circulation will change as ozone and the thermal properties of the atmosphere change, and assess how these new findings will affect our confidence in the ozone assessment results.

  18. Nitrogen Chemistry in Titan's Upper Atmosphere

    NASA Technical Reports Server (NTRS)

    McKay, Christopher P.; Cuzzi, Jeffrey (Technical Monitor)

    1996-01-01

    In Titan's upper atmosphere N2 is dissociated to N by solar UV and high energy electrons. This flux of N provides for interesting organic chemistry in the lower atmosphere of Titan. Previously the main pathway for the loss of this N was thought to be the formation of HCN, followed by diffusion of this HCN to lower altitudes leading ultimately to condensation. However, recent laboratory simulations of organic chemistry in Titan's atmosphere suggest that formation of the organic haze may be an important sink for atmospheric N. Because estimates of the eddy diffusion profile on Titan have been based on the HCN profile, inclusion of this additional sink for N will affect estimates for all transport processes in Titan's atmosphere. This and other implications of this sink for the N balance on Titan are considered.

  19. CAPACITY: Operational Atmospheric Chemistry Monitoring Missions

    NASA Astrophysics Data System (ADS)

    Kelder, H.; Goede, A.; van Weele, M.

    The ESA project CAPACITY refers to future Operational Atmospheric Chemistry Monitoring Missions. Here operational is meant in the sense that a reliable service of specified information products can be established that satisfies user needs. Monitoring is meant in the sense that long-term continuity and consistency in the quality of the information products can be achieved. The objectives of the project are: To consult with user communities to develop high level information requirements and the form of the information products. To identify and prioritise mission objectives. To derive mission data requirements from the high level user information requirements and iterate these with the users. To set these requirements against observation systems available or approved for the future. To identify missing information products or information products of insufficient quality. To define a global observation system that would satisfy user requirements. The time frame of this operational system is projected to cover the period 2010 to 2020 concurrent with the operational satellites MetOp and NPOESS. In order to address these objectives a large European consortium has been formed consisting of approximately 30 partners from 9 ESA countries (F, D, UK, I, SW, N, DK, B, NL). The project is led by the Royal Netherlands Meteorological Institute (KNMI) and the core team includes the Rutherford Appleton Laboratory, Univ Leicester, Univ Bremen and industry. Four application areas are identified: Protocol Monitoring (Montreal and Kyoto) and Policy Support Air Quality Monitoring and Policy Support (CLRTAP) Long Term Science Issues and Climate Monitoring Forecast Capacity In the derivation of data level 2/3 requirements from high level user requirements the consortium relies on a large group of modellers using satellite data, and of space research institutes with expertise in retrieval and calibration/validation of satellite data as well as Industry with experience in building space

  20. Perspective: Water cluster mediated atmospheric chemistry

    SciTech Connect

    Vaida, Veronica

    2011-07-14

    The importance of water in atmospheric and environmental chemistry initiated recent studies with results documenting catalysis, suppression and anti-catalysis of thermal and photochemical reactions due to hydrogen bonding of reagents with water. Water, even one water molecule in binary complexes, has been shown by quantum chemistry to stabilize the transition state and lower its energy. However, new results underscore the need to evaluate the relative competing rates between reaction and dissipation to elucidate the role of water in chemistry. Water clusters have been used successfully as models for reactions in gas-phase, in aqueous condensed phases and at aqueous surfaces. Opportunities for experimental and theoretical chemical physics to make fundamental new discoveries abound. Work in this field is timely given the importance of water in atmospheric and environmental chemistry.

  1. Parallel computing in atmospheric chemistry models

    SciTech Connect

    Rotman, D.

    1996-02-01

    Studies of atmospheric chemistry are of high scientific interest, involve computations that are complex and intense, and require enormous amounts of I/O. Current supercomputer computational capabilities are limiting the studies of stratospheric and tropospheric chemistry and will certainly not be able to handle the upcoming coupled chemistry/climate models. To enable such calculations, the authors have developed a computing framework that allows computations on a wide range of computational platforms, including massively parallel machines. Because of the fast paced changes in this field, the modeling framework and scientific modules have been developed to be highly portable and efficient. Here, the authors present the important features of the framework and focus on the atmospheric chemistry module, named IMPACT, and its capabilities. Applications of IMPACT to aircraft studies will be presented.

  2. ATMOSPHERIC ACIDIFICATION CHEMISTRY: A REVIEW

    EPA Science Inventory

    Atmospheric acidification is the result of the oxidation of sulfur, nitrogen, and organic compounds to form their corresponding acids. The gas and aqueous-phase pathways depend on the production of oxidizing free radicals (HO, CH3O2) that react directly with these compounds or pr...

  3. PNNL's 'PEGASUS' Advances Atmospheric Chemistry

    SciTech Connect

    Berkowitz, Carl M.; Eades, Robert A.

    2001-04-16

    Presented an overview of software design to maximize computational efficiency on a massively parallel computing system. Also gave highlights of scientific results from this code, focusing primarily on how we can distinguish between stratospheric ozone in remote atmospheres and ozone generated from NOx/VOC chemical mechanisms.

  4. Chemistry of Planetary Atmospheres: Insights and Prospects

    NASA Astrophysics Data System (ADS)

    Yung, Yuk

    2015-11-01

    Using observations from the Mariners, Pioneers, Vikings, Voyagers, Pioneer Venus, Galileo, Venus Express, Curiosity, Cassini, New Horizons, and numerous observatories both in orbit of Earth and on the ground, I will give a survey of the major chemical processes that control the composition of planetary atmospheres. For the first time since the beginning of the space age, we understand the chemistry of planetary atmospheres ranging from the primitive atmospheres of the giant planets to the highly evolved atmospheres of terrestrial planets and small bodies. Our understanding can be distilled into three important ideas: (1) The stability of planetary atmospheres against escape of their constituents to space, (2) the role of equilibrium chemistry in determining the partitioning of chemical species, and (3) the role of disequilibrium chemistry, which produces drastic departures from equilibrium chemistry. To these three ideas we must also add a fourth: the role of biochemistry at Earth's surface, which makes its atmospheric chemistry unique in the cosmochemical environment. Only in the Earth's atmosphere do strong reducing and oxidizing species coexist to such a degree. For example, nitrogen species in the Earth's atmosphere span eight oxidation states from ammonia to nitric acid. Much of the Earth's atmospheric chemistry consists of reactions initiated by the degradation of biologically produced molecules. Life uses solar energy to drive chemical reactions that would otherwise not occur; it represents a kind of photochemistry that is special to Earth, at least within the Solar System. It remains to be seen how many worlds like Earth there are beyond the Solar System, especially as we are now exploring the exoplanets using Kepler, TESS, HST, Spitzer, soon to be launched missions such as JWST and WFIRST, and ground-based telescopes. The atmospheres of the Solar System provide a benchmark for studying exoplanets, which in turn serve to test and extend our current

  5. Organic chemistry in the atmosphere. [laboratory modeling of Titan atmosphere

    NASA Technical Reports Server (NTRS)

    Sagan, C.

    1974-01-01

    The existence of an at least moderately complex organic chemistry on Titan is stipulated based on clear evidence of methane, and at least presumptive evidence of hydrogen in its atmosphere. The ratio of methane to hydrogen is the highest of any atmosphere in the solar system. Irradiation of hydrogen/methane mixtures produces aromatic and aliphatic hydrocarbons. A very reasonable hypothesis assumes that the red cloud cover of Titan is made of organic chemicals. Two-carbon hydrocarbons experimentally produced from irradiated mixtures of methane, ammonia, water, and hydrogen bear out the possible organic chemistry of the Titanian environment.

  6. 1999 Gordon Research Conference on Atmospheric Chemistry

    SciTech Connect

    Storm, C.

    2000-08-01

    The Gordon Research Conference (GRC) on Atmospheric Chemistry was held at Salve Regina University in Newport, Rhode Island, June 13-18, 1999. The conference was well attended with 151 participants. The attendees represented the spectrum of endeavor in this field coming from academia, industry, and government laboratories, both US and foreign scientists, senior researchers, young investigators, and students.

  7. 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.

  8. The PHOCUS Project: Atmospheric Composition

    NASA Astrophysics Data System (ADS)

    Hedin, J.; Gumbel, J.; Khaplanov, M.

    2012-12-01

    On the morning of July 21, 2011, the PHOCUS sounding rocket was launched from Esrange, Sweden, into strong noctilucent clouds (NLC) and polar mesosphere summer echoes (PMSE). The aim of the PHOCUS project (Particles, Hydrogen and Oxygen Chemistry in the Upper Summer mesosphere) is to study mesospheric particles (ice and meteoric smoke) and their interaction with their neutral and charged environment. Interactions of interest comprise the charging and nucleation of particles, the relationship between meteoric smoke and ice, and the influence of these particles on gas-phase chemistry. Here we will describe the optical measurements of the atmospheric composition and present first results including comparison to the other simultaneous measurements. The atmospheric composition was probed by a set of optical instruments from Stockholm University. The idea behind the instrument setup was to combine the advantages of the sensitive resonance fluorescence with well-calibrated airglow photometry. The set of instruments consisted of two resonance fluorescence probes (each containing a lamp and a detector), one for atomic oxygen and one for atomic hydrogen, and two IR photometers for O2 and OH dayglow emissions in the near IR. The O2 IR Atmospheric system at 1.27 μm is related to the photolysis of O3, which during the day is in steady state with O and a retrieval of O is possible. The OH Meinel emission is produced by the reaction between mesospheric O3 and H, and H concentrations can be deduced by combining information from both photometers. Unfortunately, some of these measurements were corrupted by instrument problems or payload glow. O3 and O profiles will be presented and compared to the simultaneous measurements of ice and meteoric smoke particles, water vapour and the state of the background neutral and charged atmosphere.

  9. New insights into martian atmospheric chemistry

    NASA Astrophysics Data System (ADS)

    Boxe, C. S.; Francisco, J. S.; Shia, R.-L.; Yung, Y. L.; Nair, H.; Liang, M.-C.; Saiz-Lopez, A.

    2014-11-01

    HOx radicals are produced in the martian atmosphere by the photolysis of water vapor and subsequently participate in catalytic cycles that recycle carbon dioxide (CO2) from its photolysis product carbon monoxide (CO), providing a qualitative explanation for the stability of its atmosphere. Balancing CO2 production and loss based on our current understanding of martian gas-phase chemistry has, however, proven to be difficult. The photolysis of O3 produces O(1D), while oxidation of CO produces HOCO radicals, a new member of the HOx family. The O(1D) quantum yield has recently been updated, which quantifies nonzero quantum yields in the Huggins bands. In Earth's atmosphere HOCO is considered to be unimportant since it is quickly removed by abundant oxygen molecules. The smaller amount of O2 in the Mars' atmosphere causes HOCO's lifetime to be longer in Mars' atmosphere than Earth's (3 × 10-5 s to 1.2 days from Mars's surface to 240 km, respectively). Limited kinetic data on reactions involving HOCO prevented consideration of its reactions directly in atmospheric models. Therefore, the impact of HOCO reactions on martian chemistry is currently unknown. Here, we incorporate new literature rate constants for HOCO chemistry and an updated representation of the O(1D) quantum yield in the Caltech/JPL 1-D photochemical model for Mars' atmosphere. Our simulations exemplify perturbations to NOy, HOx, and COx species, ranging from 5% to 50%. The modified O(1D) quantum yield and new HOCO chemistry cause a 10% decrease and a 50% increase in OH and H2O2 total column abundances, respectively. At low altitudes, HOCO production contributes 5% towards CO2 production. Given recent experimentally-obtained branching ratios for the oxidation of CO, HOCO may contribute up to 70% toward the production of NOy, where HOx and NOy species are enhanced up to a factor 3, which has implications for rethinking the fundamental understanding of NOy, HOx, and CO/CO2 cycling on Mars. Two new reaction

  10. Evaluation of Preindustrial to Present-day Black Carbon and its Albedo Forcing from Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

    SciTech Connect

    Lee, Y. H.; Lamarque, J.-F.; Flanner, M. G.; Jiao, C.; Shindell, Drew; Berntsen, T.; Bisiauxs, M.; Cao, J.; Collins, W. J.; Curran, M.; Edwards, R.; Faluvegi, G.; Ghan, Steven J.; Horowitz, L.; McConnell, J.R.; Ming, J.; Myhre, G.; Nagashima, T.; Naik, Vaishali; Rumbold, S.; Skeie, R. B.; Sudo, K.; Takemura, T.; Thevenon, F.; Xu, B.; Yoon, Jin-Ho

    2013-03-05

    As a part of the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), we evaluate the historical black carbon (BC) aerosols simulated by 8 ACCMIP models against the observations including 12 ice core records, a long-term surface mass concentrations and recent Arctic BC snowpack measurements. We also estimate BC albedo forcing by performing additional simulations using the NCAR Community Land and Sea-Ice model 4 with prescribed meteorology from 1996-2000, which includes the SNICAR BC-snow model. We evaluated the vertical profile of BC snow concentrations from these offline simulations to using recent BC snowpack measurements. Despite using the same BC emissions, global BC burden differs by approximately a factor of 3 among models due to the differences in aerosol removal parameterizations and simulated meteorology among models; 34 Gg to 103 Gg in 1850 and 82 Gg to 315 Gg in 2000. However,models agree well on 2.5~3 times increase in the global BC burden from preindustrial to present-day, which matches with the 2.5 times increase in BC emissions. We find a large model diversity at both NH and SH high latitude regions for BC burden and at SH high latitude regions for deposition fluxes. The ACCMIP simulations match the observed BC mass concentrations well in Europe and North America except at Jungfrauch and Ispra. However, the models fail to capture the Arctic BC seasonality due tosevere underestimations during winter and spring. Compared to recent snowpack measurements, the simulated vertically resolved BC snow concentrations are, on average, within a factor of 2-3 of observations except for Greenland and Arctic Ocean. However, model and observation differ widely due to missing interannual variations in emissions and possibly due to the choice of the prescribed meteorology period (i.e., 1996-2000).

  11. Is microbiolgy an alternative route to photochemistry in atmospheric chemistry?

    NASA Astrophysics Data System (ADS)

    Vaitilingom, M.; Parazols, M.; Sancelme, M.; Deguillaume, L.; Mailhot, G.; Delort, A.-M.

    2009-04-01

    Until very recently scientists from atmospheric sciences focussed their studies on physical and chemical phenomena taking place in cloud water phase neglecting the presence of active microorganisms in this medium. For instance, considering atmospheric chemistry, solar light is considered as the predominant catalyser for chemical reactions occurring in the atmosphere. However recent studies show that living and active microorganisms, including bacteria, yeasts and fungi, are present in the atmospheric water phase and could play an active role in chemistry of clouds. Indeed living microorganisms are clearly biocatalysts which could transform organic compounds as an alternative route to photochemistry. The objective of our project is to bring answers to this new scientific question by a multidisciplinary approach involving atmospheric physicists, photochemists and microbiologists. Microorganisms have been isolated and identified in cloud water sampled at the puy de Dôme summit which is an atmospheric observatory and a European referenced site. Laboratory experiments were carried out to evaluate the potential of organic species (carboxylic acids) degradation by the photochemical or microbiological ways. The project was centred on few carboxylic acids among them succinic, acetic, formic and oxalic acids (the most important organic acids in cloud water sampled at Puy de Dôme). Degradation rates were measured during biodegradation alone (Pseudomonas syringae), photochemistry alone (hydrogen peroxide + light) and combing both processed using artificial reconstituted cloud water. Our first results show that the obtained degradation rates are in the range of order.

  12. Chemistry and evolution of Titan's atmosphere

    NASA Technical Reports Server (NTRS)

    Strobel, D. F.

    1982-01-01

    The chemistry and evolution of Titan's atmosphere are reviewed, in light of the scientific findings from the Voyager mission. It is argued that the present N2 atmosphere may be Titan's initial atmosphere, rather than one photochemically derived from an original NH3 atmosphere. The escape rate of hydrogen from Titan is controlled by photochemical production from hydrocarbons. CH4 is irreversibly converted to less hydrogen-rich hydrocarbons, which over geologic time accumulate on the surface to a layer thickness of about 0.5 km. Magnetospheric electrons interacting with Titan's exosphere may dissociate enough N2 into hot, escaping N atoms to remove about 0.2 of Titan's present atmosphere over geologic time. The energy dissipation of magnetospheric electrons exceeds solar EUV energy deposition in Titan's atmosphere by an order of magnitude, and is the principal driver of nitrogen photochemistry. The environmental conditions in Titan's upper atmosphere are favorable to building up complex molecules, particularly in the north polar cap region.

  13. DATA USER'S GUIDE TO THE MOUNTAIN CLOUD CHEMISTRY PROJECT

    EPA Science Inventory

    Atmospheric pollution is deposited on the forests of the eastern United States in a variety of forms. oncern has been raised that the exposure to and deposition of these atmospheric pollutants may play a role in the decline of these forests. he Mountain Cloud Chemistry Project (M...

  14. Atmospheric Prebiotic Chemistry and Organic Hazes.

    PubMed

    Trainer, Melissa G

    2013-08-01

    Earth's atmospheric composition at the time of the origin of life is not known, but it has often been suggested that chemical transformation of reactive species in the atmosphere was a significant source of prebiotic organic molecules. Experimental and theoretical studies over the past half century have shown that atmospheric synthesis can yield molecules such as amino acids and nucleobases, but these processes are very sensitive to gas composition and energy source. Abiotic synthesis of organic molecules is more productive in reduced atmospheres, yet the primitive Earth may not have been as reducing as earlier workers assumed, and recent research has reflected this shift in thinking. This work provides a survey of the range of chemical products that can be produced given a set of atmospheric conditions, with a particular focus on recent reports. Intertwined with the discussion of atmospheric synthesis is the consideration of an organic haze layer, which has been suggested as a possible ultraviolet shield on the anoxic early Earth. Since such a haze layer - if formed - would serve as a reservoir for organic molecules, the chemical composition of the aerosol should be closely examined. The results highlighted here show that a variety of products can be formed in mildly reducing or even neutral atmospheres, demonstrating that contributions of atmospheric synthesis to the organic inventory on early Earth should not be discounted. This review intends to bridge current knowledge of the range of possible atmospheric conditions in the prebiotic environment and pathways for synthesis under such conditions by examining the possible products of organic chemistry in the early atmosphere. PMID:24143126

  15. Atmospheric Prebiotic Chemistry and Organic Hazes

    NASA Technical Reports Server (NTRS)

    Trainer, Melissa G.

    2012-01-01

    Earth's atmospheric composition at the time of the origin of life is not known, but it has often been suggested that chemical transformation of reactive species in the atmosphere was a significant source of pre biotic organic molecules. Experimental and theoretical studies over the past half century have shown that atmospheric synthesis can yield molecules such as amino acids and nucleobases, but these processes are very sensitive to gas composition and energy source. Abiotic synthesis of organic molecules is more productive in reduced atmospheres, yet the primitive Earth may not have been as reducing as earlier workers assumed, and recent research has reflected this shift in thinking. This work provides a survey of the range of chemical products that can be produced given a set of atmospheric conditions, with a particular focus on recent reports. Intertwined with the discussion of atmospheric synthesis is the consideration of an organic haze layer, which has been suggested as a possible ultraviolet shield on the anoxic early Earth. Since such a haze layer - if formed - would serve as a reservoir for organic molecules, the chemical composition of the aerosol should be closely examined. The results highlighted here show that a variety of products can be formed in mildly reducing or even neutral atmospheres, demonstrating that contributions of atmospheric synthesis to the organic inventory on early Earth should not be discounted. This review intends to bridge current knowledge of the range of possible atmospheric conditions in the prebiotic environment and pathways for synthesis under such conditions by examining the possible products of organic chemistry in the early atmosphere.

  16. Atmospheric Prebiotic Chemistry and Organic Hazes

    PubMed Central

    Trainer, Melissa G.

    2013-01-01

    Earth’s atmospheric composition at the time of the origin of life is not known, but it has often been suggested that chemical transformation of reactive species in the atmosphere was a significant source of prebiotic organic molecules. Experimental and theoretical studies over the past half century have shown that atmospheric synthesis can yield molecules such as amino acids and nucleobases, but these processes are very sensitive to gas composition and energy source. Abiotic synthesis of organic molecules is more productive in reduced atmospheres, yet the primitive Earth may not have been as reducing as earlier workers assumed, and recent research has reflected this shift in thinking. This work provides a survey of the range of chemical products that can be produced given a set of atmospheric conditions, with a particular focus on recent reports. Intertwined with the discussion of atmospheric synthesis is the consideration of an organic haze layer, which has been suggested as a possible ultraviolet shield on the anoxic early Earth. Since such a haze layer – if formed – would serve as a reservoir for organic molecules, the chemical composition of the aerosol should be closely examined. The results highlighted here show that a variety of products can be formed in mildly reducing or even neutral atmospheres, demonstrating that contributions of atmospheric synthesis to the organic inventory on early Earth should not be discounted. This review intends to bridge current knowledge of the range of possible atmospheric conditions in the prebiotic environment and pathways for synthesis under such conditions by examining the possible products of organic chemistry in the early atmosphere. PMID:24143126

  17. Submillimeter Planetary Atmospheric Chemistry Exploration Sounder

    NASA Technical Reports Server (NTRS)

    Schlecht, Erich T.; Allen, Mark A.; Gill, John J.; Choonsup, Lee; Lin, Robert H.; Sin, Seth; Mehdi, Imran; Siegel, Peter H.; Maestrini, Alain

    2013-01-01

    Planetary Atmospheric Chemistry Exploration Sounder (SPACES), a high-sensitivity laboratory breadboard for a spectrometer targeted at orbital planetary atmospheric analysis. The frequency range is 520 to 590 GHz, with a target noise temperature sensitivity of 2,500 K for detecting water, sulfur compounds, carbon compounds, and other atmospheric constituents. SPACES is a prototype for a powerful tool for the exploration of the chemistry and dynamics of any planetary atmosphere. It is fundamentally a single-pixel receiver for spectral signals emitted by the relevant constituents, intended to be fed by a fixed or movable telescope/antenna. Its front-end sensor translates the received signal down to the 100-MHz range where it can be digitized and the data transferred to a spectrum analyzer for processing, spectrum generation, and accumulation. The individual microwave and submillimeter wave components (mixers, LO high-powered amplifiers, and multipliers) of SPACES were developed in cooperation with other programs, although with this type of instrument in mind. Compared to previous planetary and Earth science instruments, its broad bandwidth (approx. =.13%) and rapid tunability (approx. =.10 ms) are new developments only made possible recently by the advancement in submillimeter circuit design and processing at JPL.

  18. Atmospheric Chemistry of Micrometeoritic Organic Compounds

    NASA Technical Reports Server (NTRS)

    Kress, M. E.; Belle, C. L.; Pevyhouse, A. R.; Iraci, L. T.

    2011-01-01

    Micrometeorites approx.100 m in diameter deliver most of the Earth s annual accumulation of extraterrestrial material. These small particles are so strongly heated upon atmospheric entry that most of their volatile content is vaporized. Here we present preliminary results from two sets of experiments to investigate the fate of the organic fraction of micrometeorites. In the first set of experiments, 300 m particles of a CM carbonaceous chondrite were subject to flash pyrolysis, simulating atmospheric entry. In addition to CO and CO2, many organic compounds were released, including functionalized benzenes, hydrocarbons, and small polycyclic aromatic hydrocarbons. In the second set of experiments, we subjected two of these compounds to conditions that simulate the heterogeneous chemistry of Earth s upper atmosphere. We find evidence that meteor-derived compounds can follow reaction pathways leading to the formation of more complex organic compounds.

  19. On the chemistry of Jupiter's upper atmosphere

    USGS Publications Warehouse

    Saslaw, W.C.; Wildey, R.L.

    1967-01-01

    We conduct a first investigation into the ion-molecule chemistry of the upper Jovian atmosphere. Experimental results show that intense ultraviolet radiation reacts with the constituents of the Jovian atmosphere to produce C2H4, C2H6, C3H8, and higher polymers. The general procedure for calculating both equilibrium and nonequilibrium abundances of these products is formulated and applied to the case of the surface passage of a satellite shadow. A specific example is made of ethylene, for which an analytical approximation gives 1010 molecules in an atmospheric column of 1 cm2 cross section after a very rapid rise to equilibrium. Such a concentration of ethylene does not substantially affect the infrared radiation in the shadow. ?? 1967.

  20. Chemistry of Earth's Putative Steam Atmosphere

    NASA Astrophysics Data System (ADS)

    Fegley, B.; Schaefer, L.

    2007-12-01

    The concept of a steam atmosphere generated by impact devolatilization of planetesimals accreted during Earth's formation is over 20 years old (Matsui and Abe, 1986; Lange and Ahrens, 1982). Surprisingly, with the possible exception of a few qualitative remarks, no one has critically assessed this scenario. We use thermochemical equilibrium and, where relevant, thermochemical kinetic calculations to model the chemistry of the "steam" atmosphere produced by impact volatilization of different types of accreting material. We present results for our nominal conditions (1500 K, total P = 100 bar). We also studied the effects of variable temperature and total pressure. The composition of the accreting material is modeled using average compositions of the Orgueil CI chondrite, the Murchison CM2 chondrite, the Allende CV3 chondrite, average ordinary (H, L, LL) chondrites, and average enstatite (EH, EL) chondrites. The major gases released from CI and CM chondritic material are H2O, CO2, H2, H2S, CO, CH4, and SO2 in decreasing order of abundance. About 10% of the atmosphere is CO2. The major gases released from CV chondritic material are CO2, H2O, CO, H2, and SO2 in decreasing order of abundance. About 20% of the total atmosphere is steam. The major gases released from average ordinary chondritic material are H2, CO, H2O, CO2, CH4, H2S, and N2 in decreasing order of abundance. The "steam" atmosphere is predominantly H2 + CO with steam being about 10% of the total atmosphere. The major gases released from EH chondritic material are H2, CO, H2O, CO2, N2, and CH4 in decreasing order of abundance. The "steam" atmosphere is predominantly H2 + CO with about 10% of the total atmosphere as steam. This work was supported by the NASA Astrobiology and Origins Programs.

  1. Trace Element Chemistry in Urban Atmospheric Aerosols

    NASA Astrophysics Data System (ADS)

    Farhana, B.; Husain, L.

    2006-12-01

    Unlike in the United States, the concentration of trace elements in urban air is still high enough in South Asian cities to study the impact of trace elements on climate and human health. Hence, continuous sampling of PM2.5 (particulate matter of <2.5 μm aerodynamic diameter)was carried out using low volume sampler in winter (2005-2006) in Lahore, the second largest city of Pakistan, which is highly impacted by urban and agricultural emissions and has remained unexplored in terms of atmospheric chemistry. Aerosols collected on this campaign are likely to carry the signatures of emissions from Afghanistan, North and Central Pakistan, North India in addition to the local pollution sources. During sampling from December 2005 to January 2006, it was possible to collect several samples during brief fog episodes. Samples were analyzed for 25 elements (Be, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, As, Se, Sr, Mo, Ag, Cd, Sn, Sb, Ba, Tl and Pb) using inductively coupled plasma mass spectrometry. High pollutant concentrations were observed throughout the study, for instance, Cr concentrations up to 1.4 μgm-3, As, 135 ngm-3, Cd, 93 ngm-3, Sn, 988 ngm-3 and Sb, 157 ngm-3. Pb and Zn concentrations respectively up to 12 and 48 μgm-3 were observed. Calculation of enrichment factor and crustal correction illustrate the attribution of Cr, Co, Ni, Zn, As, Se, Mo, Ag Cd, Sn, Sb, Tl and Pb to non-crustal sources. Air parcel back trajectories, interelemental relationships and meteorological observations have been used to explain the sources and the impacts of fog chemistry and mixing heights on atmospheric processing of trace elements in PM2.5. Atmospheric stagnation appeared to be one of factors causing episodic high concentrations. Crustal correction and interelemental relationships apparently suggest the emissions from coal and oil combustion, industrial processes, building construction sites and biomass burning as the prime role players in the atmospheric pollution in

  2. Preindustrial to Present-Day Changes in Tropospheric Hydroxyl Radical and Methane Lifetime from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

    NASA Technical Reports Server (NTRS)

    Naik, V.; Voulgarakis, A.; Fiore, A. M.; Horowitz, L. W.; Lamarque, J.-F.; Lin, M.; Prather, M. J.; Young, P. J.; Bergmann, D.; Cameron-Smith, P. J.; Cionni, I.; Collins, W. J.; Dalsoren, S. B.; Doherty, R.; Eyring, V.; Faluvegi, G.; Folberth, G. A.; Josse, B.; Lee, Y. H.; MacKenzie, I. A.; Nagashima, T.; vanNoije, T. P. C.; Plummer, D. A.; Righi, M.; Rumbold, S. T.; Skeie, R.; Shindell, D. T.; Stevenson, D. S.; Strode, S.; Sudo, K.; Szopa, S.; Zeng, G.

    2013-01-01

    We have analysed time-slice simulations from 17 global models, participating in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), to explore changes in present-day (2000) hydroxyl radical (OH) concentration and methane (CH4) lifetime relative to preindustrial times (1850) and to 1980. A comparison of modeled and observation-derived methane and methyl chloroform lifetimes suggests that the present-day global multi-model mean OH concentration is overestimated by 5 to 10% but is within the range of uncertainties. The models consistently simulate higher OH concentrations in the Northern Hemisphere (NH) compared with the Southern Hemisphere (SH) for the present-day (2000; inter-hemispheric ratios of 1.13 to 1.42), in contrast to observation-based approaches which generally indicate higher OH in the SH although uncertainties are large. Evaluation of simulated carbon monoxide (CO) concentrations, the primary sink for OH, against ground-based and satellite observations suggests low biases in the NH that may contribute to the high north–south OH asymmetry in the models. The models vary widely in their regional distribution of present-day OH concentrations (up to 34%). Despite large regional changes, the multi-model global mean (mass-weighted) OH concentration changes little over the past 150 yr, due to concurrent increases in factors that enhance OH (humidity, tropospheric ozone, nitrogen oxide (NOx) emissions, and UV radiation due to decreases in stratospheric ozone), compensated by increases in OH sinks (methane abundance, carbon monoxide and non-methane volatile organic carbon (NMVOC) emissions). The large inter-model diversity in the sign and magnitude of preindustrial to present-day OH changes (ranging from a decrease of 12.7% to an increase of 14.6%) indicate that uncertainty remains in our understanding of the long-term trends in OH and methane lifetime. We show that this diversity is largely explained by the different ratio of the

  3. Atmospheric chemistry - Response to human influence

    NASA Technical Reports Server (NTRS)

    Logan, J. A.; Prather, M. J.; Wofsy, S. G.; Mcelroy, M. B.

    1978-01-01

    Global atmospheric chemistry is surveyed, and the agreement of models with observed distribution of gases is considered. The influence of human perturbations due to combustion, agriculture, and chloro-carbon releases is examined with emphasis on ozone. Effects of combustion-related releases of CO on the abundances of other gases as well as possible effects of CO on tropospheric ozone are discussed. Other topics include the contribution of the chlorocarbon industry to stratospheric chloride and the recombination of nitrogen fixed by agriculture and combustion.

  4. Ion Chemistry in Atmospheric and Astrophysical Plasmas

    NASA Technical Reports Server (NTRS)

    Dalgarno, A.; Fox, J. L.

    1994-01-01

    There are many differences and also remarkable similarities between the ion chemistry and physics of planetary ionospheres and the ion chemistry and physics of astronomical environments beyond the solar system. In the early Universe, an expanded cooling gas of hydrogen and helium was embedded in the cosmic background radiation field and ionized by it. As the Universe cooled by adiabatic expansion, recombination occurred and molecular formation was driven by catalytic reactions involving the relict electrons and protons. Similar chemical processes are effective in the ionized zones of gaseous and planetary nebulae and in stellar winds where the ionization is due to radiation from the central stars, in the envelopes of supernovae where the ionization is initiated by the deposition of gamma-rays, in dissociative shocks where the ionization arises from electron impacts in a hot gas and in quasar broad-line region clouds where the quasar is responsible for the ionization. At high altitudes in the atmospheres of the Jovian planets, the main constituents are hydrogen and helium and the ion chemistry and physics is determined by the same processes, the source of the ionization being solar ultraviolet radiation and cosmic rays. After the collapse of the first distinct astronomical entities to emerge from the uniform flow, heavy elements were created by nuclear burning in the cores of the collapsed objects and distributed throughout the Universe by winds and explosions. The chemistry and physics became more complicated. Over 90 distinct molecular species have been identified in interstellar clouds where they are ionized globally by cosmic ray impacts and locally by radiation and shocks associated with star formation and evolution. Complex molecules have also been found in circumstellar shells of evolved stars. At intermediate and low altitudes in the Jovian atmospheres, the ion chemistry is complicated by the increasing abundance of heavy elements such as carbon, and an

  5. THE ADVANCED CHEMISTRY BASINS PROJECT

    SciTech Connect

    William Goddard; Peter Meulbroek; Yongchun Tang; Lawrence Cathles III

    2004-04-05

    In the next decades, oil exploration by majors and independents will increasingly be in remote, inaccessible areas, or in areas where there has been extensive shallow exploration but deeper exploration potential may remain; areas where the collection of data is expensive, difficult, or even impossible, and where the most efficient use of existing data can drive the economics of the target. The ability to read hydrocarbon chemistry in terms of subsurface migration processes by relating it to the evolution of the basin and fluid migration is perhaps the single technological capability that could most improve our ability to explore effectively because it would allow us to use a vast store of existing or easily collected chemical data to determine the major migration pathways in a basin and to determine if there is deep exploration potential. To this end a the DOE funded a joint effort between California Institute of Technology, Cornell University, and GeoGroup Inc. to assemble a representative set of maturity and maturation kinetic models and develop an advanced basin model able to predict the chemistry of hydrocarbons in a basin from this input data. The four year project is now completed and has produced set of public domain maturity indicator and maturation kinetic data set, an oil chemistry and flash calculation tool operable under Excel, and a user friendly, graphically intuitive basin model that uses this data and flash tool, operates on a PC, and simulates hydrocarbon generation and migration and the chemical changes that can occur during migration (such as phase separation and gas washing). The DOE Advanced Chemistry Basin Model includes a number of new methods that represent advances over current technology. The model is built around the concept of handling arbitrarily detailed chemical composition of fluids in a robust finite-element 2-D grid. There are three themes on which the model focuses: chemical kinetic and equilibrium reaction parameters, chemical

  6. Evaluation of preindustrial to present-day black carbon and its albedo forcing from Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

    NASA Technical Reports Server (NTRS)

    Lee, Y. H.; Lamarque, J.-F.; Flanner, M. G.; Jiao, C.; Shindell, D. T.; Bernsten, T.; Bisiaux, M. M.; Cao, J.; Collins, W. J.; Curran, M.; Edwards, R.; Faluvegi, G.; Ghan, S.; Horowitz, L. W.; McConnell, J. R.; Ming, J.; Myhre, G.; Nagashima, T.; Naik, V.; Rumbold, S. T.; Skeie, R. B.; Sudo, K.; Takemura, T.; Thevenon, F.; Xu, B.; Yoon, J.-H.

    2013-01-01

    As part of the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), we evaluate the historical black carbon (BC) aerosols simulated by 8 ACCMIP models against observations including 12 ice core records, long-term surface mass concentrations, and recent Arctic BC snowpack measurements. We also estimate BC albedo forcing by performing additional simulations using offline models with prescribed meteorology from 1996-2000. We evaluate the vertical profile of BC snow concentrations from these offline simulations using the recent BC snowpack measurements. Despite using the same BC emissions, the global BC burden differs by approximately a factor of 3 among models due to differences in aerosol removal parameterizations and simulated meteorology: 34 Gg to 103 Gg in 1850 and 82 Gg to 315 Gg in 2000. However, the global BC burden from preindustrial to present-day increases by 2.5-3 times with little variation among models, roughly matching the 2.5-fold increase in total BC emissions during the same period.We find a large divergence among models at both Northern Hemisphere (NH) and Southern Hemisphere (SH) high latitude regions for BC burden and at SH high latitude regions for deposition fluxes. The ACCMIP simulations match the observed BC surface mass concentrations well in Europe and North America except at Ispra. However, the models fail to predict the Arctic BC seasonality due to severe underestimations during winter and spring. The simulated vertically resolved BC snow concentrations are, on average, within a factor of 2-3 of the BC snowpack measurements except for Greenland and the Arctic Ocean. For the ice core evaluation, models tend to adequately capture both the observed temporal trends and the magnitudes at Greenland sites. However, models fail to predict the decreasing trend of BC depositions/ice core concentrations from the 1950s to the 1970s in most Tibetan Plateau ice cores. The distinct temporal trend at the Tibetan Plateau ice cores

  7. The atmospheric chemistry of iodine monoxide

    SciTech Connect

    Laszlo, B.; Huie, R.E.

    1995-12-01

    The possible role of iodine on tropospheric ozone arid, more recently, stratospheric ozone has been of considerable interest. There have been, however relatively few experimental determination of the chemistry of the important radical, IO. Laser flash photolysis with two-wavelength transient absorption experiments were performed on N{sub 2}O/I{sub 2}+X{sub 2}/N{sub 2} mixtures (X{sub 2} = halogen) at room temperature and total pressure between 8 and 80 kPa. An extended IO absorption spectrum, experimental rate coefficients of IO+IO, IO+O({sup 3}P), IO+BrO, BrO+I and IO+ClO reactions will be presented. Preliminary results show the atmospheric importance of reaction between alkylperoxy radicals and iodine atoms or iodine monoxide radicals. These reactions seem to be important tropospheric iodine sinks.

  8. Jupiter: Aerosol Chemistry in the Polar Atmosphere.

    PubMed

    Wong; Lee; Yung; Ajello

    2000-05-10

    Aromatic compounds have been considered a likely candidate for enhanced aerosol formation in the polar region of Jupiter. We develop a new chemical model for aromatic compounds in the Jovian auroral thermosphere/ionosphere. The model is based on a previous model for hydrocarbon chemistry in the Jovian atmosphere and is constrained by observations from Voyager, Galileo, and the Infrared Space Observatory. Precipitation of energetic electrons provides the major energy source for the production of benzene and other heavier aromatic hydrocarbons. The maximum mixing ratio of benzene in the polar model is 2x10-9, a value that can be compared with the observed value of 2+2-1x10-9 in the north polar auroral region. Sufficient quantities of the higher ring species are produced so that their saturated vapor pressures are exceeded. Condensation of these molecules is expected to lead to aerosol formation. PMID:10813686

  9. Atmospheric Chemistry Experiment (ACE) Measurements of Tropospheric and Stratospheric Chemistry and Long-Term Trends

    NASA Technical Reports Server (NTRS)

    Rinsland, Curtis P.; Bernath, Peter; Boone, Chris; Nassar, Ray

    2007-01-01

    We highlight chemistry and trend measurement results from the Atmospheric Chemistry Experiment (ACE) which is providing precise middle troposphere to the lower thermosphere measurements with a 0.02/cm resolution Fourier transform spectrometer covering 750-4400/cm

  10. Tampa Bay Regional Atmospheric Chemistry Experiment: Overview

    NASA Astrophysics Data System (ADS)

    Atkeson, T. D.

    2003-12-01

    The Tampa Bay Estuary Program (TBEP) was formed in 1991 to assist in developing a comprehensive plan to restore and protect Tampa Bay in Florida, USA. An ecological indicator of the health of the Bay is the coverage of seagrasses, historically in decline, which are important to the aquatic habitat and food web of the bay. Seagrass decline is linked to excess of plant-stimulating forms of nitrogen to the bay, promoting algae growth, which shades out light needed to sustain seagrasses. One element of the TBEP is a private-local-state, multi-agency Nitrogen Management Consortium that seeks to limit nitrogen loading to the Bay to the 1992-1994 average. Present estimates suggest atmospheric deposition comprises ~ 30% of the nitrogen budget of the Bay. This estimate was based, however, on limited ambient monitoring data and simple models, typical of such national estuary program efforts nationwide. In the Bay Regional Atmospheric Chemistry Experiment Florida DEP joined with TBEP to increase the intensity, sophistication and spatial scope of monitoring and modeling and provide better information on air quality in the Tampa Bay area. The result will be improved estimates of the effects of local and regional emissions of oxides of nitrogen (NOx) on the Bay and the benefits to be gained from implementation of emissions reduction strategies.

  11. Technique for atmospheric rate chemistry calculations. [of SST exhaust

    NASA Technical Reports Server (NTRS)

    Matloff, G. L.

    1976-01-01

    The possibility that predictions of atmospheric photochemistry/transport models are sensitive to uncertainties in reaction rates and other inputs stresses the need for rapid numerical integration schemes in rate photochemistry problems. Reducing the computational burden has a major merit in facilitating sensitivity studies to assess the effect of uncertainties on predicted ozone diminutions from NOx (NO + NO2) in the exhaust plume of SST engines. The paper discusses the validity of an algorithmic approach to integration of rate chemistry problems in combustion, developed by Rubel and Baronti for an approximate calculation of the production rate of the i-th chemical species involved. An analysis of two projected SST engines confirms the validity of the proposed algorithm. Because of the relative arithmetical simplicity, it may be easier to treat diffusion rate chemistry calculations using the Rubel and Baronti approximation than would be possible by other approaches.

  12. Atmospheric Chemistry of Acenaphthalene and Acenaphthylene

    NASA Astrophysics Data System (ADS)

    Zhou, S.; Wenger, J. C.

    2009-04-01

    Polycyclic aromatic hydrocarbons (PAHs) are released into the atmosphere as a by-product of combustion processes and have been detected in ambient air at urban locations around the world. In the atmosphere, PAHs containing two and three rings are found predominantly in the gas-phase, whilst those containing six or more rings principally adsorb to particles. PAHs with four or five rings are found in both phases. The gas-phase PAHs can be chemically transformed in the lower troposphere via reaction with hydroxyl (OH) and nitrate (NO3) radicals and ozone. These reactions lead to the formation of a range of oxidation products including phenols, nitro-PAHs and carbonyls, in addition to other pollutants such as ozone and secondary organic aerosol (SOA). Despite their importance, relatively little is known about the atmospheric chemistry of the PAHs, mainly because of the difficulty of working with these compounds and also the variety and complexity of the reaction products formed. Up to now only one kinetic study on the reaction of acenaphthalene and acenaphthylene with OH, NO3 and ozone has been reported in the peer-reviewed literature. In this study, we have determined rate coefficients for the gas-phase reactions of acenaphthalene and acenaphthylene with OH, NO3 and ozone using the relative rate method. The results are compared with previous measurements and used to provide estimates of the tropospheric lifetimes of these compounds. A recently developed denuder-filter sampling technique was used to investigate the gas and particle phase products arising from the photooxidation of the PAHs. Chemical analysis was performed using gas chromatography - mass spectrometry using O-(2,3,4,5,6- pentafluorobenzyl)-hydroxylamine (PFBHA) and pentafluorobenzyl bromide (PFBBr) as derivatizing agents for carbonyls and phenols respectively. The results provide new data on the gas-particle partitioning behavior of the oxidation products and useful information on the products likely to

  13. Measurement and Chemistry of Atmospheric Organic Nitrates

    NASA Astrophysics Data System (ADS)

    Buhr, Martin Patrick

    1990-01-01

    Organic nitrates are important reservoir species for NO_{rm x} (NO + NO_2) in the atmosphere. Typically formed in and around urban areas, the organic nitrates sequester NO_{rm x} and allow it to be transported to rural and remote regions, wherein it may be released into the atmosphere and participate in catalytic cycles leading to the formation of ozone. The research described in this work focusses on two problems related to our understanding of the atmospheric chemistry of the organic nitrates, (1) measuring the organic nitrates contributions to total reactive nitrogen (NO_ {rm y}) in the atmosphere, and (2) determining the conditions under which the organic nitrates release NO_{rm x} into the atmosphere and thereby participate in ozone formation. The work performed included development of measurement methods for the organic nitrates, ambient measurements of several organic nitrates made under a variety of conditions, and data interpretation using a combination of bivariate and multivariate analysis. The instrument development that was performed centered around incorporation of capillary column technology in a gas chromatographic method. Use of a capillary column resulted in improved chromatographic resolution and instrument sensitivity. In addition to the work on the chromatographic separation of the organic nitrates, some work was done regarding the sensitivity of the electron capture detector (ECD) as a function of electrical mode of operation. Ambient measurements of several of the organic nitrates were made during three field experiments in conjunction with NOAA's Aeronomy laboratory, including PAN rm CH_3C(O)O_2NO_2), PPN rm (C_2H_5C(O)O_2NO _2), and the C_1-C _5 alkyl nitrates (RONO_2 ). The measurements were made in conjunction with a wide variety of other chemical and physical parameters. Data interpretation was performed using bivariate analysis in order to understand the diurnal variation of the concentrations of the organic nitrates and their

  14. The Atmospheric Chemistry of Methyl Chavicol (Estragole)

    NASA Astrophysics Data System (ADS)

    Bloss, W. J.; Alam, M. S.; Rickard, A. R.; Hamilton, J. F.; Pereira, K. F.; Camredon, M.; Munoz, A.; Vazquez, M.; Alacreu, P.; Rodenas, M.; Vera, T.

    2012-12-01

    The oxidation of volatile organic compounds (VOCs) leads to formation of ozone and secondary organic aerosols (SOA), with consequences for health, air quality, crop yields, atmospheric chemistry and radiative transfer. It is estimated that ca. 90 % of VOC emissions to the atmosphere originate from biogenic sources (BVOC); such emissions may increase under future climates. Recent field observations have identified Methyl Chavicol ("MC" hereafter, also known as Estragole; 1-allyl-4-methoxybenzene, C10H12O) as a major BVOC above pine forests in the USA [Bouvier-Brown et al., 2009], and within an oil palm plantation in Malaysian Borneo, where it was found that MC could represent the highest single floral contribution of reactive carbon to the atmosphere [Misztal et al., 2010]. Palm oil cultivation, and hence emissions of MC, may be expected to increase with societal food and biofuel demand. We present the results of a series of simulation chamber experiments to assess the atmospheric fate of MC. Experiments were performed in the EUPHORE (European Photoreactor) facility in Valencia, Spain (200 m3 outdoor smog chamber), investigating the degradation of MC by reaction with OH, O3 and NO3. An extensive range of measurement instrumentation was used to monitor precursor and product formation, including stable species (FTIR, PTR-MS, GC-FID and GC-MS), radical intermediates (LIF), inorganic components (NOx, O3, HONO (LOPAP and aerosol production (SMPS) and composition (PILS and filters; analysed offline by LC-MS and FTICR-MS). Experiments were conducted at a range of NOx:VOC ratios, and in the presence and absence of radical (OH) scavenger compounds. This chamber dataset is used to determine the rate constants for reaction of MC with OH, O3 and NO3, the ozonolysis radical yields, and identify the primary degradation products for each initiation route, alongside the aerosol mass yields. Aerosol composition measurements are analysed to identify markers for MC contributions to

  15. A Cooperative Chemistry Project: Chemsource.

    ERIC Educational Resources Information Center

    Giles, Catherine Y.

    1994-01-01

    Chemsource is a set of instructional materials designed as a resource for high school chemistry teachers, particularly those not trained in the discipline. Materials consist of a videotape demonstrating both generic and science-specific teaching skills and a textbook on varied chemistry topics, including suggested teaching techniques and…

  16. Parametric Analyses of Potential Effects on Stratospheric and Tropospheric Ozone Chemistry by a Fleet of Supersonic Business Jets Projected in a 2020 Atmosphere

    NASA Technical Reports Server (NTRS)

    Wey, Chowen (Technical Monitor); Dutta, M.; Patten, K.; Wuebbles, D.

    2004-01-01

    A class of new supersonic aircraft for business purposes is currently under consideration for use starting around 2015 to 2020. These aircraft, which can accommodate about 12 to 13 passengers, will fly at a speed of Mach 1.6 to 2 and are commonly termed as Supersonic Business Jets (SSBJs). A critical issue that needs to be addressed during the conception phase of such aircraft is the potential impact of emissions from such aircraft on the atmosphere especially on stratospheric ozone. Although these SSBJs will be much smaller in size and will have smaller engines than the hypothetical fleets of commercial passenger High Speed Civil Transport (HSCT) aircraft that we have studied previously, they will still emit nitrogen oxides (NOx = NO + NO2), carbon dioxide (CO2), water vapor (H2O) and sulfur, the latter if it is still in the fuel. Thus, it is important to design these SSBJs in a manner so that a projected fleet of these aircraft will not have a significant effect on ozone or on climate. This report analyzes the potential impact of a fleet of SSBJs in a set of parametric analyses that examine the envelope of potential effects on ozone over a range of total fuel burns, emission indices of nitrogen oxides (E.I.(NOx)), and cruise altitudes, using the current version of the UIUC zonally-averaged two-dimensional model of the global atmosphere.

  17. National Chemistry Week 2003: Earth's Atmosphere and Beyond. JCE Resources for Chemistry and the Atmosphere

    NASA Astrophysics Data System (ADS)

    Jacobsen, Erica K.

    2003-10-01

    This annotated bibliography collects the best that past issues of the Journal of Chemical Education have to offer for use with this year's National Chemistry Week theme: Earth's Atmosphere and Beyond. Each article has been characterized as a demonstration, experiment, activity, informational, or software/video item; several fit in more than one classification. The most recent articles are listed first. Also included is an evaluation as to which levels the article may serve. Articles that appeared adaptable to other levels, but are not designed explicitly for those levels, are labeled "poss. h.s." "poss. elem.", and so forth.

  18. [Global Atmospheric Chemistry/Transport Modeling and Data-Analysis

    NASA Technical Reports Server (NTRS)

    Prinn, Ronald G.

    1999-01-01

    This grant supported a global atmospheric chemistry/transport modeling and data- analysis project devoted to: (a) development, testing, and refining of inverse methods for determining regional and global transient source and sink strengths for trace gases; (b) utilization of these inverse methods which use either the Model for Atmospheric Chemistry and Transport (MATCH) which is based on analyzed observed winds or back- trajectories calculated from these same winds for determining regional and global source and sink strengths for long-lived trace gases important in ozone depletion and the greenhouse effect; (c) determination of global (and perhaps regional) average hydroxyl radical concentrations using inverse methods with multiple "titrating" gases; and (d) computation of the lifetimes and spatially resolved destruction rates of trace gases using 3D models. Important ultimate goals included determination of regional source strengths of important biogenic/anthropogenic trace gases and also of halocarbons restricted by the Montreal Protocol and its follow-on agreements, and hydrohalocarbons now used as alternatives to the above restricted halocarbons.

  19. Gridded global surface ozone metrics for atmospheric chemistry model evaluation

    NASA Astrophysics Data System (ADS)

    Sofen, E. D.; Bowdalo, D.; Evans, M. J.; Apadula, F.; Bonasoni, P.; Cupeiro, M.; Ellul, R.; Galbally, I. E.; Girgzdiene, R.; Luppo, S.; Mimouni, M.; Nahas, A. C.; Saliba, M.; Tørseth, K.

    2016-02-01

    The concentration of ozone at the Earth's surface is measured at many locations across the globe for the purposes of air quality monitoring and atmospheric chemistry research. We have brought together all publicly available surface ozone observations from online databases from the modern era to build a consistent data set for the evaluation of chemical transport and chemistry-climate (Earth System) models for projects such as the Chemistry-Climate Model Initiative and Aer-Chem-MIP. From a total data set of approximately 6600 sites and 500 million hourly observations from 1971-2015, approximately 2200 sites and 200 million hourly observations pass screening as high-quality sites in regionally representative locations that are appropriate for use in global model evaluation. There is generally good data volume since the start of air quality monitoring networks in 1990 through 2013. Ozone observations are biased heavily toward North America and Europe with sparse coverage over the rest of the globe. This data set is made available for the purposes of model evaluation as a set of gridded metrics intended to describe the distribution of ozone concentrations on monthly and annual timescales. Metrics include the moments of the distribution, percentiles, maximum daily 8-hour average (MDA8), sum of means over 35 ppb (daily maximum 8-h; SOMO35), accumulated ozone exposure above a threshold of 40 ppbv (AOT40), and metrics related to air quality regulatory thresholds. Gridded data sets are stored as netCDF-4 files and are available to download from the British Atmospheric Data Centre (doi: 10.5285/08fbe63d-fa6d-4a7a-b952-5932e3ab0452). We provide recommendations to the ozone measurement community regarding improving metadata reporting to simplify ongoing and future efforts in working with ozone data from disparate networks in a consistent manner.

  20. Gridded global surface ozone metrics for atmospheric chemistry model evaluation

    NASA Astrophysics Data System (ADS)

    Sofen, E. D.; Bowdalo, D.; Evans, M. J.; Apadula, F.; Bonasoni, P.; Cupeiro, M.; Ellul, R.; Galbally, I. E.; Girgzdiene, R.; Luppo, S.; Mimouni, M.; Nahas, A. C.; Saliba, M.; Tørseth, K.; Wmo Gaw, Epa Aqs, Epa Castnet, Capmon, Naps, Airbase, Emep, Eanet Ozone Datasets, All Other Contributors To

    2015-07-01

    The concentration of ozone at the Earth's surface is measured at many locations across the globe for the purposes of air quality monitoring and atmospheric chemistry research. We have brought together all publicly available surface ozone observations from online databases from the modern era to build a consistent dataset for the evaluation of chemical transport and chemistry-climate (Earth System) models for projects such as the Chemistry-Climate Model Initiative and Aer-Chem-MIP. From a total dataset of approximately 6600 sites and 500 million hourly observations from 1971-2015, approximately 2200 sites and 200 million hourly observations pass screening as high-quality sites in regional background locations that are appropriate for use in global model evaluation. There is generally good data volume since the start of air quality monitoring networks in 1990 through 2013. Ozone observations are biased heavily toward North America and Europe with sparse coverage over the rest of the globe. This dataset is made available for the purposes of model evaluation as a set of gridded metrics intended to describe the distribution of ozone concentrations on monthly and annual timescales. Metrics include the moments of the distribution, percentiles, maximum daily eight-hour average (MDA8), SOMO35, AOT40, and metrics related to air quality regulatory thresholds. Gridded datasets are stored as netCDF-4 files and are available to download from the British Atmospheric Data Centre (doi:10.5285/08fbe63d-fa6d-4a7a-b952-5932e3ab0452). We provide recommendations to the ozone measurement community regarding improving metadata reporting to simplify ongoing and future efforts in working with ozone data from disparate networks in a consistent manner.

  1. Session on coupled atmospheric/chemistry coupled models

    NASA Technical Reports Server (NTRS)

    Thompson, Anne

    1993-01-01

    The session on coupled atmospheric/chemistry coupled models is reviewed. Current model limitations, current issues and critical unknowns, and modeling activity are addressed. Specific recommendations and experimental strategies on the following are given: multiscale surface layer - planetary boundary layer - chemical flux measurements; Eulerian budget study; and Langrangian experiment. Nonprecipitating cloud studies, organized convective systems, and aerosols - heterogenous chemistry are also discussed.

  2. Collaborative Research. Atmospheric Pressure Microplasma Chemistry-Photon Synergies

    SciTech Connect

    Park, Sung-Jin; Eden, James Gary

    2015-12-01

    Combining the effects of low temperature, atmospheric pressure microplasmas and microplasma photon sources offers the promise of greatly expanding the range of applications for each of them. The plasma sources create active chemical species and these can be activated further by the addition of photons and the associated photochemistry. There are many ways to combine the effects of plasma chemistry and photochemistry, especially if there are multiple phases present. This project combined the construction of appropriate test experimental systems, various spectroscopic diagnostics and mathematical modeling. Through a continuous discussion and co-design process with the UC-Berkeley Team, we have successfully completed the fabrication and testing of all components for a microplasma array-assisted system designed for photon-activated plasma chemistry research. Microcavity plasma lamps capable of generating more than 20 mW/cm2 at 172 nm (Xe dimer) were fabricated with a custom form factor to mate to the plasma chemistry setup, and a lamp was current being installed by the Berkeley team so as to investigate plasma chemistry-photon synergies at a higher photon energy (~7.2 eV) as compared to the UVA treatment that is afforded by UV LEDs operating at 365 nm. In particular, motivated by the promising results from the Berkeley team with UVA treatment, we also produced the first generation of lamps that can generate photons in the 300-370 nm wavelength range. Another set of experiments, conducted under the auspices of this grant, involved the use of plasma microjet arrays. The combination of the photons and excited radicals produced by the plasma column resulted in broad area deactivation of bacteria.

  3. LABORATORY AND COMPUTATIONAL CHEMISTRY INVESTIGATIONS OF THE GAS PHASE ATMOSPHERIC CHEMISTRY OF AIR TOXIC COMPOUNDS

    EPA Science Inventory

    A full assessment of the impact of the release of air toxic compounds into the atmospheric requires a detailed understanding of their atmospheres lifetimes and fates. To address this issue a detailed review of the atmospheric chemistry of each of these classes was carried out t...

  4. Sulfur Chemistry in the Early and Present Atmosphere of Mars

    NASA Technical Reports Server (NTRS)

    Levine, Joel S.; Summers, M. E.

    2011-01-01

    Atmospheric sulfur species resulting from volcanic emissions impact the composition and chemistry of the atmosphere, impact the climate, and hence, the habitability of Mars and impact the mineralogy and composition of the surface of Mars. The geochemical/ photochemical cycling of sulfur species between the interior (via volcanism), the atmosphere (atmospheric photochemical and chemical processes) and the deposition of sulfuric acid on the surface of Mars is an important, but as yet poorly understood geochemical/ photochemical cycle on Mars. There is no observational evidence to indicate that Mars is volcanically active at the present time, however, there is strong evidence that volcanism was an important and widespread process on early Mars. The chemistry and photochemistry of sulfur species in the early and present atmosphere of Mars will be assessed using a one-dimensional photochemical model. Since it is generally assumed that the atmosphere of early Mars was significantly denser than the present 6-millibar atmosphere, photochemical calculations were performed for the present atmosphere and for the atmosphere of early Mars with assumed surface pressures of 60 and 350-millibars, where higher surface pressure resulted from enhanced atmospheric concentrations of carbon dioxide (CO2). The following sections include the results of earlier modeling studies, a summary of the one-dimensional photochemical model used in this study, a summary of the photochemistry and chemistry of sulfur species in the atmosphere of Mars and some of the results of the calculations.

  5. 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...

  6. Concluding remarks: Faraday Discussion on chemistry in the urban atmosphere.

    PubMed

    Jimenez, Jose L

    2016-07-18

    This article summarises the Concluding remarks from the Faraday Discussion on Chemistry in the Urban Atmosphere. The following themes are addressed: (a) new results that inform our understanding of the evolving sources and composition of the urban atmosphere ("News"); (b) results that identify gaps in our understanding that necessitate further work ("Gaps"); PMID:27363779

  7. COMPUTATIONAL CHEMISTRY: AN EMERGING TECHNOLOGY FOR SOLVING PROBLEMS IN ATMOSPHERIC CHEMISTRY

    EPA Science Inventory

    Over the past three decades, atmospheric chemistry has served as an important component in developing strategies for reducing ambient concentrations of air pollutants. Laboratory studies are carried out to investigate the key chemical reactions that determine the fates and lif...

  8. Hydrogen chemistry - Perspective on experiment and theory. [atmospheric chemistry

    NASA Technical Reports Server (NTRS)

    Kaufman, F.

    1975-01-01

    A review is presented of the advantages and limitations of various experimental methods for the investigation of the kinetics of hydrogen chemistry, including classic thermal and photochemical methods and the crossed molecular beam method. Special attention is given to the flash photolysis-resonance fluorescence apparatus developed by Braun et al, in which repetitive vacuum UV flashes result in the photolytic generation of the desired species, and to the discharge-flow technique. The use of various theoretical methods for the selection or elimination of kinetic data is considered in a brief discussion of the rate theory of two-body encounters and recombination-dissociation processes in neutral reactions. Recent kinetic studies of a series of OH reactions and of a major loss process for odd H in the stratosphere are summarized.

  9. Air-snow interactions and atmospheric chemistry.

    PubMed

    Dominé, Florent; Shepson, Paul B

    2002-08-30

    The presence of snow greatly perturbs the composition of near-surface polar air, and the higher concentrations of hydroxyl radicals (OH) observed result in a greater oxidative capacity of the lower atmosphere. Emissions of nitrogen oxides, nitrous acid, light aldehydes, acetone, and molecular halogens have also been detected. Photolysis of nitrate ions contained in the snow appears to play an important role in creating these perturbations. OH formed in the snowpack can oxidize organic matter and halide ions in the snow, producing carbonyl compounds and halogens that are released to the atmosphere or incorporated into snow crystals. These reactions modify the composition of the snow, of the interstitial air, and of the overlying atmosphere. Reconstructing the composition of past atmospheres from ice-core analyses may therefore require complex corrections and modeling for reactive species. PMID:12202818

  10. Atmospheric chemistry: The return of ethane

    NASA Astrophysics Data System (ADS)

    Hakola, Hannele; Hellén, Heidi

    2016-07-01

    Ethane emissions can lead to ozone pollution. Measurements at 49 sites show that long-declining atmospheric ethane concentrations started rising in 2010 in the Northern Hemisphere, largely due to greater oil and gas production in the USA.

  11. Air-Snow Interactions and Atmospheric Chemistry

    NASA Astrophysics Data System (ADS)

    Dominé, Florent; Shepson, Paul B.

    2002-08-01

    The presence of snow greatly perturbs the composition of near-surface polar air, and the higher concentrations of hydroxyl radicals (OH) observed result in a greater oxidative capacity of the lower atmosphere. Emissions of nitrogen oxides, nitrous acid, light aldehydes, acetone, and molecular halogens have also been detected. Photolysis of nitrate ions contained in the snow appears to play an important role in creating these perturbations. OH formed in the snowpack can oxidize organic matter and halide ions in the snow, producing carbonyl compounds and halogens that are released to the atmosphere or incorporated into snow crystals. These reactions modify the composition of the snow, of the interstitial air, and of the overlying atmosphere. Reconstructing the composition of past atmospheres from ice-core analyses may therefore require complex corrections and modeling for reactive species.

  12. Chemistry [Sahuarita High School Career Curriculum Project].

    ERIC Educational Resources Information Center

    Lane, Robert

    This course entitled "Chemistry" is one of a series of instructional guides prepared by teachers for the Sahuarita High School (Arizona) Career Curriculum Project. It consists of three packages, the first dealing with solids, liquids and solutions, the second with acids, bases and anions, and the third with cation analysis. These packages are…

  13. Chemistry and Writing: A Collaborative Writing Project.

    ERIC Educational Resources Information Center

    Hamilton, Todd M.

    2000-01-01

    Describes a collaborative writing project at Adrian College in Michigan. Students in a general chemistry class collaborated with those from a freshman writing course; the intention was to have students combine their talents to improve their ability to express scientific ideas in a clear and accurate manner. Discusses student reactions and…

  14. Multiple oscillations in Neoarchaean atmospheric chemistry

    NASA Astrophysics Data System (ADS)

    Izon, Gareth; Zerkle, Aubrey L.; Zhelezinskaia, Iadviga; Farquhar, James; Newton, Robert J.; Poulton, Simon W.; Eigenbrode, Jennifer L.; Claire, Mark W.

    2015-12-01

    The Great Oxidation Event (GOE) represents a crucial juncture in Earth history, signifying the rise in atmospheric oxygen from parts per million to percent levels at ∼2.45-2.32 billion-years-ago (Ga). Although planetary oxygenation undoubtedly led to the inception of the contemporary Earth system, the trigger(s) and mechanism(s) controlling this chemical reorganisation remain elusive. Quantitative estimates of the atmosphere's composition in the prelude to the GOE are central to understanding this oxygenation event. Previous analyses of 2.65-2.5 Ga sediments from the Griqualand Basin (South Africa) invoke a tantalising picture of an unusual Earth environment, alluding to an atmosphere periodically dominated by a layer of organic particles ("haze") formed from methane photolysis. However, as yet this hypothesis has remained untested. Here we present four new coupled carbon and quadruple sulphur isotope records from distal, time equivalent (2.7-2.5 Ga), sedimentary successions from South Africa and Western Australia. These extended records reveal similar chemostratigraphic trends, supporting a dynamic terminal-Neoarchaean atmosphere, oscillating between a hazy state at elevated methane concentrations, and a haze-free anoxic background state. We suggest these atmospheric aberrations were related to heightened biogenic methane fluxes fuelled by enhanced nutrient delivery from climatically or weathering induced feedbacks. These data question the canonical view of a simple, unidirectional planetary oxygenation and signify that the overture to the GOE was governed by complex feedbacks within the Earth-biosphere system.

  15. Lookup tables to compute high energy cosmic ray induced atmospheric ionization and changes in atmospheric chemistry

    SciTech Connect

    Atri, Dimitra; Melott, Adrian L.; Thomas, Brian C. E-mail: melott@ku.edu

    2010-05-01

    A variety of events such as gamma-ray bursts and supernovae may expose the Earth to an increased flux of high-energy cosmic rays, with potentially important effects on the biosphere. Existing atmospheric chemistry software does not have the capability of incorporating the effects of substantial cosmic ray flux above 10 GeV. An atmospheric code, the NASA-Goddard Space Flight Center two-dimensional (latitude, altitude) time-dependent atmospheric model (NGSFC), is used to study atmospheric chemistry changes. Using CORSIKA, we have created tables that can be used to compute high energy cosmic ray (10 GeV–1 PeV) induced atmospheric ionization and also, with the use of the NGSFC code, can be used to simulate the resulting atmospheric chemistry changes. We discuss the tables, their uses, weaknesses, and strengths.

  16. NESTED GRID MESOSCALE ATMOSPHERIC CHEMISTRY MODEL

    EPA Science Inventory

    A nested grid version of the Regional Acid Deposition Model (RADM) has been developed. he horizontal grid interval size of the nested model is 3 times smaller than that of RADM (80/3 km 26.7 km). herefore the nested model is better able to simulate mesoscale atmospheric processes...

  17. Real-time atmospheric chemistry field instrumentation.

    PubMed

    Farmer, Delphine K; Jimenez, Jose L

    2010-10-01

    Quantifying the concentrations of trace atmospheric species in complex, reactive, and constantly changing gas and particle mixtures is challenging. This article provides a broad overview of recent advances in instrumentation used for analyzing ambient gases and particles continuously and with fast time resolution during field campaigns. PMID:20722374

  18. Multiphase Chemistry of Pyruvic Acid Under Atmospherically Relevant Conditions

    NASA Astrophysics Data System (ADS)

    Vaida, V.; Monod, A.; Doussin, J. F.; Reed Harris, A. E.; Griffith, E. C.; Kroll, J. A.; Rapf, R.

    2014-12-01

    Chemistry in the natural environment proceeds in multiple phases and is subject to effects from atmospheric constituents and conditions. This presentation will use pyruvic acid as a case study to demonstrate the complexity of atmospheric multiphase chemistry. The photophysics and photochemistry of pyruvic acid proceeds on different potential energy surfaces with different reaction mechanisms, rates, and products in gas versus the aqueous phase. While the gas phase reaction generally decreases the complexity of products, the aqueous chemistry creates higher molecular weight, surface-active compounds. The studies presented involve a combination of laboratory studies that focus on the photochemistry of pyruvic acid in both the gas and aqueous phases. Further, experiments in an environmental simulation chamber (CESAM) that follow the photochemistry chemistry of pyruvic acid under atmospherically relevant conditions will be presented to highlight the effect of pressure, oxygen, relative humidity, and phase on the photochemistry of pyruvic acid. The results provide new input for atmospheric chemistry models that is required to better describe the behavior of α-keto acids in the environment.

  19. Atmospherically relevant ion chemistry of ozone and its cation.

    PubMed

    de Petris, Giulia

    2003-01-01

    The importance of ionic processes that occur in terrestrial, planetary, and stellar atmospheres is receiving increasing recognition. Actually, ions play important, often crucial, roles in a variety of atmospheric processes throughout the universe, and a strong link with the neutral chemistry is also apparent. In the terrestrial atmosphere, the ionic reactions are most relevant in those transient and fleeting events, e.g., lightning, coronas (in thunderstorm clouds and along power lines), where the local ion density is much higher than in unperturbed air, and the chemical systems are typically far from equilibrium. In such cases, ozone, a key molecule for the terrestrial atmosphere, is also present in high local concentrations; it is formed from O(2) by the same transient event. Accordingly, this review provides a survey of the positive ion chemistry of ozone with several of the most important "atmospheric" species: the reactions, the products, and the importance of the examined processes are discussed also in the light of the local thermodynamic disequilibrium (LTD) approach to the chemistry of transient atmospheric events. In all such studies, mass spectrometry is traditionally, and remains today, the experimental technique of choice. The novel application of mass spectrometry to the study of neutral species (NRMS), highly successful for the preparation and positive detection of long-sought, otherwise inaccessible, short-lived neutrals, makes mass spectrometry the most powerful tool now available for the study of the species and processes that are relevant to atmospheric chemistry. Selected examples of the interlink between the neutral and the ionic chemistry are also illustrated. PMID:12884389

  20. ATMOSPHERIC CHEMISTRY OF SELECTED HYDROXYCARBONYLS. (R825252)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  1. Response of lightning NOx emissions and ozone production to climate change: Insights from the Atmospheric Chemistry and Climate Model Intercomparison Project

    NASA Astrophysics Data System (ADS)

    Finney, D. L.; Doherty, R. M.; Wild, O.; Young, P. J.; Butler, A.

    2016-05-01

    Results from an ensemble of models are used to investigate the response of lightning nitrogen oxide emissions to climate change and the consequent impacts on ozone production. Most models generate lightning using a parameterization based on cloud top height. With this approach and a present-day global emission of 5 TgN, we estimate a linear response with respect to changes in global surface temperature of +0.44 ± 0.05 TgN K-1. However, two models using alternative approaches give +0.14 and -0.55 TgN K-1 suggesting that the simulated response is highly dependent on lightning parameterization. Lightning NOx is found to have an ozone production efficiency of 6.5 ± 4.7 times that of surface NOx sources. This wide range of efficiencies across models is partly due to the assumed vertical distribution of the lightning source and partly to the treatment of nonmethane volatile organic compound (NMVOC) chemistry. Careful consideration of the vertical distribution of emissions is needed, given its large influence on ozone production.

  2. Parallel processing of atmospheric chemistry calculations: Preliminary considerations

    SciTech Connect

    Elliott, S.; Jones, P.

    1995-01-01

    Global climate calculations are already saturating the class modern vector supercomputers with only a few central processing units. Increased resolution and inclusion of routines to deal with biogeochemical portions of the terrestrial climate system will soon demand massively parallel approaches. The atmospheric photochemistry ensemble is intimately linked to climate through the trace greenhouse gases ozone and methane and modules for representing it are being attached to global three dimensional transport and GCM frameworks. Atmospheric kinetics involve dozens of highly interactive tracers and so will accentuate the need for parallel processing of earth system simulations. In the present text we lay some of the groundwork for addition of atmospheric kinetics packages to GCM and global scale atmospheric models on multiply parallel computers. The discussion is tailored for consumption by the photochemical modelling community. After a review of numerical atmospheric chemistry methods, we examine how kinetics can be implemented on a parallel computer. We concentrate especially on data layout and flexibility and how these can be implemented in various programming models. We conclude that chemistry can be implemented rather easily within existing frameworks of several parallel atmospheric models. However, memory limitations may preclude high resolution studies of global chemistry.

  3. Equilibrium and Disequilibrium Chemistry in Evolved Exoplanet Atmospheres

    NASA Astrophysics Data System (ADS)

    Hu, Renyu

    2015-11-01

    It has been found that sub-Neptune-sized planets, although not existing in our Solar System, are ubiquitous in our interstellar neighborhood. This revelation is profound because, due to their special sizes and proximity to their host stars, Neptune- and sub-Neptune-sized exoplanets may have highly evolved atmospheres. I will discuss helium-dominated atmospheres as one of the outcomes of extensive atmospheric evolution on warm Neptune- and sub-Neptune-sized exoplanets. Due to depleted hydrogen abundance, the dominant carbon and oxygen species may not be methane or water on these evolved planets. Equilibrium and disequilibrium chemistry models are used to compute the molecular compositions of the atmospheres and their spectral features. Applications to GJ 436 b and other Neptune- and sub-Neptune-sized exoplanets will be discussed. As the observations to obtain the spectra of these planets continue to flourish, we will have the opportunity to study unconventional atmospheric chemical processes and test atmosphere evolution theories

  4. Equilibrium and Disequilibrium Chemistry in Evolved Exoplanet Atmospheres

    NASA Astrophysics Data System (ADS)

    Hu, Renyu

    2015-12-01

    It has been found that sub-Neptune-sized planets, although not existing in our Solar System, are ubiquitous in our interstellar neighborhood. This revelation is profound because, due to their special sizes and proximity to their host stars, Neptune- and sub-Neptune-sized exoplanets may have highly evolved atmospheres. I will discuss helium-dominated atmospheres as one of the outcomes of extensive atmospheric evolution on warm Neptune- and sub-Neptune-sized exoplanets. Due to depleted hydrogen abundance, the dominant carbon and oxygen species may not be methane or water on these evolved planets. Equilibrium and disequilibrium chemistry models are used to compute the molecular compositions of the atmospheres and their spectral features. Applications to GJ 436 b and other Neptune- and sub-Neptune-sized exoplanets will be discussed. As the observations to obtain the spectra of these planets continue to flourish, we will have the opportunity to study unconventional atmospheric chemical processes and test atmosphere evolution theories

  5. Effects of Deep Convection on Atmospheric Chemistry

    NASA Technical Reports Server (NTRS)

    Pickering, Kenneth E.

    2007-01-01

    This presentation will trace the important research developments of the last 20+ years in defining the roles of deep convection in tropospheric chemistry. The role of deep convection in vertically redistributing trace gases was first verified through field experiments conducted in 1985. The consequences of deep convection have been noted in many other field programs conducted in subsequent years. Modeling efforts predicted that deep convection occurring over polluted continental regions would cause downstream enhancements in photochemical ozone production in the middle and upper troposphere due to the vertical redistribution of ozone precursors. Particularly large post-convective enhancements of ozone production were estimated for convection occurring over regions of pollution from biomass burning and urban areas. These estimates were verified by measurements taken downstream of biomass burning regions of South America. Models also indicate that convective transport of pristine marine boundary layer air causes decreases in ozone production rates in the upper troposphere and that convective downdrafts bring ozone into the boundary layer where it can be destroyed more rapidly. Additional consequences of deep convection are perturbation of photolysis rates, effective wet scavenging of soluble species, nucleation of new particles in convective outflow, and the potential fix stratosphere-troposphere exchange in thunderstorm anvils. The remainder of the talk will focus on production of NO by lightning, its subsequent transport within convective clouds . and its effects on downwind ozone production. Recent applications of cloud/chemistry model simulations combined with anvil NO and lightning flash observations in estimating NO Introduction per flash will be described. These cloud-resolving case-study simulations of convective transport and lightning NO production in different environments have yielded results which are directly applicable to the design of lightning

  6. Ozone Depletion, UVB and Atmospheric Chemistry

    NASA Technical Reports Server (NTRS)

    Stolarski, Richard S.

    1999-01-01

    The primary constituents of the Earth's atmosphere are molecular nitrogen and molecular oxygen. Ozone is created when ultraviolet light from the sun photodissociates molecular oxygen into two oxygen atoms. The oxygen atoms undergo many collisions but eventually combine with a molecular oxygen to form ozone (O3). The ozone molecules absorb ultraviolet solar radiation, primarily in the wavelength region between 200 and 300 nanometers, resulting in the dissociation of ozone back into atomic oxygen and molecular oxygen. The oxygen atom reattaches to an O2 molecule, reforming ozone which can then absorb another ultraviolet photon. This sequence goes back and forth between atomic oxygen and ozone, each time absorbing a uv photon, until the oxygen atom collides with and ozone molecule to reform two oxygen molecules.

  7. Laboratory Studies of Atmospheric Heterogeneous Chemistry

    NASA Technical Reports Server (NTRS)

    Keyser, L. F.; Leu, M-T.

    1993-01-01

    In the laboratory, ice films formed by freezing from the liquid or more frequently by deposition from the vapor phase have been used to simulate stratospheric cloud surfaces for measurements of reaction and uptake rates. To obtain intrinsic surface reaction probabilities that can be used in atmospheric models, the area of the film surface that actually takes part in the reaction must be known. It is important to know not only the total surface area but also the film morphology in order to determine where and how the surface is situated and, thus, what fraction of it is available for reaction. Information on the structure of these ice films has been obtained by using several experimental methods. In the sections that follow, these methods will be discussed, then the results will be used to construct a working model of the ice films, and finally the model will be applied to an experimental study of HC1 uptake by H_2O ice.

  8. Atmospheric chemistry of i-butanol.

    PubMed

    Andersen, V F; Wallington, T J; Nielsen, O J

    2010-12-01

    Smog chamber/FTIR techniques were used to determine rate constants of k(Cl + i-butanol) = (2.06 ± 0.40) × 10(-10), k(Cl + i-butyraldehyde) = (1.37 ± 0.08) × 10(-10), and k(OH + i-butanol) = (1.14 ± 0.17) × 10(-11) cm(3) molecule(-1) s(-1) in 700 Torr of N(2)/O(2) diluent at 296 ± 2K. The UV irradiation of i-butanol/Cl(2)/N(2) mixtures gave i-butyraldehyde in a molar yield of 53 ± 3%. The chlorine atom initiated oxidation of i-butanol in the absence of NO gave i-butyraldehyde in a molar yield of 48 ± 3%. The chlorine atom initiated oxidation of i-butanol in the presence of NO gave (molar yields): i-butyraldehyde (46 ± 3%), acetone (35 ± 3%), and formaldehyde (49 ± 3%). The OH radical initiated oxidation of i-butanol in the presence of NO gave acetone in a yield of 61 ± 4%. The reaction of chlorine atoms with i-butanol proceeds 51 ± 5% via attack on the α-position to give an α-hydroxy alkyl radical that reacts with O(2) to give i-butyraldehyde. The atmospheric fate of (CH(3))(2)C(O)CH(2)OH alkoxy radicals is decomposition to acetone and CH(2)OH radicals. The atmospheric fate of OCH(2)(CH(3))CHCH(2)OH alkoxy radicals is decomposition to formaldehyde and CH(3)CHCH(2)OH radicals. The results are consistent with, and serve to validate, the mechanism that has been assumed in the estimation of the photochemical ozone creation potential of i-butanol. PMID:21049965

  9. Chemistry in the near-surface atmosphere at Ganymede

    NASA Astrophysics Data System (ADS)

    Shematovich, V. I.

    2013-09-01

    Theoretical predictions of the composition and chemical evolution of near-surface atmospheres of the icy satellites in the Jovian and Kronian systems are of great importance for assessing the biological potential of these satellites. Depending on the satellite mass the formation of the rarefied exosphere with the relatively dense near-surface layer is possible as, for example, in the case of the relatively heavy Galilean satellites Europa and Ganymede in the Jovian system [1-3]. Ganymede is of special interest, because observations indicate that Ganymede has a significant O2 near - surface atmosphere, probably subsurface ocean, and is the only satellite with its own magnetosphere. Processes of formation of the rarefied gaseous envelope of Ganymede and chemical exchange between atmosphere and icy surface will be considered. The water vapour is usually the domin ant parent species in such gaseous envelope because of the ejection from the satellite icy surface due to the thermal outgassing, non-thermal photolysis and radiolysis and other active processes at work on the surface. The photochemis try of water vapour in the near - surface atmospheric layer [4] and the radiolysis of icy regolith [5] result in the supplement of the atmosphere by an admixture of H2, O2, OH and O. Returning molecules have species-dependent behaviour on contact with icy surface of the satellite and non-thermal energy distributions for the chemical radicals. The H2 and O2 molecules stick with very low efficiency and are immediately desorbed thermally, but returning H2O, OH, H and O stick to the grains in the icy regolith with unit efficiency. The suprathermal radicals OH, H, and O entering the regolith can drive the surface chemistry. The numerical kinetic model to investigate on the molecular level the chemistry of the atmosphere - surface interface of the rarefied Н2О-dominant gaseous envelope at Ganymede was developed. Such numerical model simulates the gas-phase and diffusive surface

  10. Multiple steady states in atmospheric chemistry

    NASA Technical Reports Server (NTRS)

    Stewart, Richard W.

    1993-01-01

    The equations describing the distributions and concentrations of trace species are nonlinear and may thus possess more than one solution. This paper develops methods for searching for multiple physical solutions to chemical continuity equations and applies these to subsets of equations describing tropospheric chemistry. The calculations are carried out with a box model and use two basic strategies. The first strategy is a 'search' method. This involves fixing model parameters at specified values, choosing a wide range of initial guesses at a solution, and using a Newton-Raphson technique to determine if different initial points converge to different solutions. The second strategy involves a set of techniques known as homotopy methods. These do not require an initial guess, are globally convergent, and are guaranteed, in principle, to find all solutions of the continuity equations. The first method is efficient but essentially 'hit or miss' in the sense that it cannot guarantee that all solutions which may exist will be found. The second method is computationally burdensome but can, in principle, determine all the solutions of a photochemical system. Multiple solutions have been found for models that contain a basic complement of photochemical reactions involving O(x), HO(x), NO(x), and CH4. In the present calculations, transitions occur between stable branches of a multiple solution set as a control parameter is varied. These transitions are manifestations of hysteresis phenomena in the photochemical system and may be triggered by increasing the NO flux or decreasing the CH4 flux from current mean tropospheric levels.

  11. Future impact of transport emissions on the global atmospheric chemistry

    NASA Astrophysics Data System (ADS)

    Koffi, B.; Szopa, S.; Cozic, A.

    2009-04-01

    Emissions of air pollutants by road, air traffic and international shipping affect air quality and climate. Besides their effect on the ozone concentration and its related radiative forcing, they also affect the OH-concentration, i.e. the oxidizing capacity of the atmosphere. The pollutants are emitted by the three transport sectors into highly different environments. The O3 and OH potential productions induced by each of these sectors thus differ strongly. These transport emissions are expected to show drastic quantitative and geographic changes in the next decades, because of new emission regulations, increasing mobility, as well as demographic and economic growths. In addition to changes in emissions, significant changes in climate parameters such as H2O, temperature, and dynamics are expected to occur in the future global atmosphere. They will affect the oxidation processes and thereby the changes in the atmospheric concentrations induced by transport emissions. Within the EU-project QUANTIFY (Quantifying the Climate Impact of Global and European Transport Systems) the LMDz-INCA climate-chemistry model was used to estimate the effect of transport emissions on the global atmospheric chemical composition. In a first step, up-to-date emission datasets were used for the transport and non-transport anthropogenic emissions for present (2000) and future (2050, SRES A1b and B1 scenarios) using 2003 nudged meteorology. A strong reduction of the road emissions and a moderate (B1) to high (A1b) increase of the ship and aircraft emissions are expected by the year 2050. As a consequence, the impact of road emissions on ozone is shown to decrease drastically, whereas aviation would become the major transport sources of tropospheric ozone perturbation at global scale. According to the most likely scenario (A1b), the contribution of all transport modes to the ozone column would increase everywhere, reaching up to 13% in some areas such as Asia. In a second step of the study

  12. Atmospheric chemistry of gas-phase polycyclic aromatic hydrocarbons: formation of atmospheric mutagens.

    PubMed Central

    Atkinson, R; Arey, J

    1994-01-01

    The atmospheric chemistry of the 2- to 4-ring polycyclic aromatic hydrocarbons (PAH), which exist mainly in the gas phase in the atmosphere, is discussed. The dominant loss process for the gas-phase PAH is by reaction with the hydroxyl radical, resulting in calculated lifetimes in the atmosphere of generally less than one day. The hydroxyl (OH) radical-initiated reactions and nitrate (NO3) radical-initiated reactions often lead to the formation of mutagenic nitro-PAH and other nitropolycyclic aromatic compounds, including nitrodibenzopyranones. These atmospheric reactions have a significant effect on ambient mutagenic activity, indicating that health risk assessments of combustion emissions should include atmospheric transformation products. PMID:7821285

  13. Understanding atmospheric peroxyformic acid chemistry: observation, modeling and implication

    NASA Astrophysics Data System (ADS)

    Liang, H.; Chen, Z. M.; Huang, D.; Wu, Q. Q.; Huang, L. B.

    2015-01-01

    The existence and importance of peroxyformic acid (PFA) in the atmosphere has been under controversy. We present here, for the first time, the observation data for PFA from four field measurements carried out in China. These data provided powerful evidence that PFA can stay in the atmosphere, typically in dozens of pptv level. The relationship between PFA and other detected peroxides was examined. The results showed that PFA had a strong positive correlation with its homolog, peroxyacetic acid, due to their similar sources and sinks. Through an evaluation of PFA production and removal rates, we proposed that the reactions between peroxyformyl radical (HC(O)O2) and formaldehyde or the hydroperoxyl radical (HO2) were likely to be the major source and degradation into formic acid (FA) was likely to be the major sink for PFA. Based on a box model evaluation, we proposed that the HC(O)O2 and PFA chemistry was a major source for FA under low NOx conditions. Furthermore, it is found that the impact of the HC(O)O2 and PFA chemistry on radical cycling was dependent on the yield of HC(O)O2 radical from HC(O) + O2 reaction. When this yield exceeded 50%, the HC(O)O2 and PFA chemistry should not be neglected for calculating the radical budget. To make clear the exact importance of HC(O)O2 and PFA chemistry in the atmosphere, further kinetic, field and modeling studies are required.

  14. Chemistry of the atmosphere: Its impact on global change

    SciTech Connect

    Birks, J.W.; Calvert, J.G.; Sievers, R.E.

    1993-12-31

    This book is a summary of the plenary lectures of the CHEMRAWN VII Conference held in Baltimore, Maryland, 2-7 December 1991. The book draws together some interesting perspectives relating to global change from the atmospheric chemistry community from more of a chemist`s point of view than a meteorologist`s. In fact, Chemical Research Applied to World Needs (CHEMRAWN) illustrates how the international atmospheric chemistry community (the meeting was cosponsored by the International Union of Pure and Applied Chemistry and the American Chemical Society) has traditionally put forth a considerable effort to understand the global environmental impact of dumping chemicals into the atmosphere. The primary benefit of this book is the concise summary of the research issues confronting the atmospheric science community regarding global change. Being a summary of plenary lectures, the technical depth of the papers is not great. Therefore the book offers a good presentation of material to the nonspecialist who seeks to understand the issues around which the global change research community has focused.

  15. Research for the advancement of green chemistry practice: Studies in atmospheric and educational chemistry

    NASA Astrophysics Data System (ADS)

    Cullipher, Steven Gene

    Green chemistry is a philosophy of chemistry that emphasizes a decreasing dependence on limited non-renewable resources and an increasing focus on preventing pollution byproducts of the chemical industry. In short, it is the discipline of chemistry practiced through the lens of environmental stewardship. In an effort to advance the practice of green chemistry, three studies will be described that have ramifications for the practice. The first study examines the atmospheric oxidation of a hydrofluorinated ether, a third-generation CFC replacement compound with primarily unknown atmospheric degradation products. Determination of these products has the potential to impact decisions on refrigerant usage in the future. The second study examines chemistry students' development of understanding benefits-costs-risks analysis when presented with two real-world scenarios: refrigerant choice and fuel choice. By studying how benefits-costs-risks thinking develops, curricular materials and instructional approaches can be designed to better foster the development of an ability that is both necessary for green chemists and important in daily decision-making for non-chemists. The final study uses eye tracking technology to examine students' abilities to interpret molecular properties from structural information in the context of global warming. Such abilities are fundamental if chemists are to appropriately assess risks and hazards of chemistry practice.

  16. Studies of Arctic Middle Atmosphere Chemistry using Infrared Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Lindenmaier, Rodica

    The objective of this Ph.D. project is to investigate Arctic middle atmosphere chemistry using solar infrared absorption spectroscopy. These measurements were made at the Polar Environment Atmospheric Research Laboratory (PEARL) at Eureka, Nunavut, which is operated by the Canadian Network for the Detection of Atmospheric Change (CANDAC). This research is part of the CANDAC/PEARL Arctic Middle Atmosphere Chemistry theme and aims to improve our understanding of the processes controlling the stratospheric ozone budget using measurements of the concentrations of stratospheric constituents. The instrument, a Bruker IFS 125HR Fourier transform infrared (FTIR) spectrometer, has been specifically designed for high-resolution measurements over a broad spectral range and has been used to measure reactive species, source gases, reservoirs, and dynamical tracers at PEARL since August 2006. The first part of this research focuses on the optimization of ozone retrievals, for which 22 microwindows were studied and compared. The spectral region from 1000 to 1005 cm-1 was found to be the most sensitive in both the stratosphere and troposphere, giving the highest number of independent pieces of information and the smallest total error for retrievals at Eureka. Similar studies were performed in coordination with the Network for the Detection of Atmospheric Composition Change for nine other species, with the goal of improving and harmonizing the retrieval parameters among all Infrared Working Group sites. Previous satellite validation exercises have identified the highly variable polar conditions of the spring period to be a challenge. In this work, comparisons between the 125HR and ACE-FTS (Atmospheric Chemistry Experiment-Fourier transform spectrometer) from 2007 to 2010 have been used to develop strict criteria that allow the ground and satellite-based instruments to be confidently compared. After applying these criteria, the differences between the two instruments were generally

  17. What makes urban atmospheric chemistry different and special?

    NASA Astrophysics Data System (ADS)

    Harrison, Roy M.

    2016-04-01

    There has been a tendency in the atmospheric chemistry community to regard urban atmospheric chemistry as no different to global processes and to differentiate only in terms of the emissions density in models. Such an approach may be suitable for assessing the impact of urban emissions upon regional and global processes but is unsuited to generating a clear understanding of processes within the urban atmosphere itself. The urban atmosphere differentiates itself from the global atmosphere in terms of its density of emissions and relatively short timescales for chemical reaction processes, a consequence of which is that the key processes in the urban atmosphere are often different from those in the regional and remote atmosphere. This lecture will give relevant examples. One of the key aspects of both urban and rural/remote atmospheres is the oxidation of primary pollutants and the formation of secondary species. Such processes may differ markedly between urban and non-urban environments as there are major differences in the behaviour of key oxidants such as ozone, hydroxyl and NO3 radical. In the remote atmosphere the key production process for hydroxyl is through the photolysis of ozone to form excited state oxygen atoms which react with water vapour to form OH. In the urban atmosphere, concentrations of ozone are typically depressed relative to the rural atmosphere and hence this source of OH is less favourable. There are likely to be much higher concentrations of both nitrous acid and formaldehyde in the urban atmosphere whose photolysis is probably the major source of OH. Additionally, there is far more possibility for nocturnal formation of OH in the urban atmosphere from reactions of Criegee intermediates resulting from the oxidation of alkenes. As a consequence, it has been shown that winter to summer ratios of hydroxyl radical concentrations are much higher in the urban atmosphere than is typical of rural atmospheres in northern mid-latitudes. In rural

  18. NASA's Upper Atmosphere Research Program (UARP) and Atmospheric Chemistry Modeling and Analysis Program (ACMAP): Research Summaries 1997-1999

    NASA Technical Reports Server (NTRS)

    Kurylo, M. J.; DeCola, P. L.; Kaye, J. A.

    2000-01-01

    Under the mandate contained in the FY 1976 NASA Authorization Act, the National Aeronautics and Space Administration (NASA) has developed and is implementing a comprehensive program of research, technology development, and monitoring of the Earth's upper atmosphere, with emphasis on the upper troposphere and stratosphere. This program aims at expanding our chemical and physical understanding to permit both the quantitative analysis of current perturbations as well as the assessment of possible future changes in this important region of our environment. It is carried out jointly by the Upper Atmosphere Research Program (UARP) and the Atmospheric Chemistry Modeling and Analysis Program (ACMAP), both managed within the Research Division in the Office of Earth Science at NASA. Significant contributions to this effort have also been provided by the Atmospheric Effects of Aviation Project (AEAP) of NASA's Office of Aero-Space Technology. The long-term objectives of the present program are to perform research to: understand the physics, chemistry, and transport processes of the upper troposphere and the stratosphere and their control on the distribution of atmospheric chemical species such as ozone; assess possible perturbations to the composition of the atmosphere caused by human activities and natural phenomena (with a specific emphasis on trace gas geographical distributions, sources, and sinks and the role of trace gases in defining the chemical composition of the upper atmosphere); understand the processes affecting the distributions of radiatively active species in the atmosphere, and the importance of chemical-radiative-dynamical feedbacks on the meteorology and climatology of the stratosphere and troposphere; and understand ozone production, loss, and recovery in an atmosphere with increasing abundances of greenhouse gases. The current report is composed of two parts. Part 1 summarizes the objectives, status, and accomplishments of the research tasks supported

  19. Middle atmospheric ion chemistry during energetic particle events, and impacts on the neutral chemistry

    NASA Astrophysics Data System (ADS)

    Sinnhuber, M.; Winkler, H.; Wieters, N.; Kazeminejad, S.; Wissing, J. M.; Kallenrode, M.-B.; Stiller, G. P.; von Clarmann, T.

    2009-04-01

    It is well established that solar proton events (SPEs) are sources of distinct chemical disturbances in the Earth's polar atmosphere. While the observed SPE caused production of NOx, and the subsequent destruction of ozone can be reproduces quite well by atmospheric models using basic parametrizations for NOx and HOx release as a function of the particle impact ionisation rate, there are significant differences between measurements and model predictions concerning several other chemical compounds. For instance, during the October 2003 SPE, measurements of a number of species were obtained from the MIPAS instrument on-board the ENVISAT satellite. These measurements show significant enhancements of HNO3 and N2O5 as well as an increase of several chlorine species, i.e., ClO, HOCl and ClONO2. Atmospheric models cannot reproduce these chemical effects if only production of NOx and HOx is considered. The impact of positive and negative ion chemistry on the neutral composition of the middle atmosphere is investigated combining model results from the University of Bremen Ion Chemistry model UBIC with different neutral stratosphere-mesosphere models, particularly the new Bremen three-dimensional Chemistry and Transport model of the middle atmosphere. Focus of the investigation will be the impact of negative ion chemistry on the activation of chlorine radicals, and on the partitioning of NOy species. Model results will be compared to measurement data of different satellite instruments (HALOE, MIPAS, MLS) for several large SPEs (e.g., the July 2000, Oct/Nov 2003, and January 2005 events) to show that the observed chlorine activation and the increase of HNO3 can be reproduced much better if full negative ion chemistry is considered additionally to the NOx and HOx production.

  20. Evaluated kinetic and photochemical data for atmospheric chemistry

    NASA Technical Reports Server (NTRS)

    Baulch, D. L.; Cox, R. A.; Hampson, R. F., Jr.; Kerr, J. A.; Troe, J.; Watson, R. T.

    1980-01-01

    This paper contains a critical evaluation of the kinetics and photochemistry of gas phase chemical reactions of neutral species involved in middle atmosphere chemistry (10-55 km altitude). Data sheets have been prepared for 148 thermal and photochemical reactions, containing summaries of the available experimental data with notes giving details of the experimental procedures. For each reaction a preferred value of the rate coefficient at 298 K is given together with a temperature dependency where possible. The selection of the preferred value is discussed, and estimates of the accuracies of the rate coefficients and temperature coefficients have been made for each reaction. The data sheets are intended to provide the basic physical chemical data needed as input for calculations which model atmospheric chemistry. A table summarizing the preferred rate data is provided, together with an appendix listing the available data on enthalpies of formation of the reactant and product species.

  1. Recent Discoveries and Future Challenges in Atmospheric Organic Chemistry.

    PubMed

    Glasius, Marianne; Goldstein, Allen H

    2016-03-15

    Earth's atmosphere contains a multitude of organic compounds, which differ by orders of magnitude regarding fundamental properties such as volatility, reactivity, and propensity to form cloud droplets, affecting their impact on global climate and human health. Despite recent major research efforts and advances, there are still substantial gaps in understanding of atmospheric organic chemistry, hampering efforts to understand, model, and mitigate environmental problems such as aerosol formation in both polluted urban and more pristine regions. The analytical toolbox available for chemists to study atmospheric organic components has expanded considerably during the past decade, opening new windows into speciation, time resolution and detection of reactive and semivolatile compounds at low concentrations. This has provided unprecedented opportunities, but also unveiled new scientific challenges. Specific groundbreaking examples include the role of epoxides in aerosol formation especially from isoprene, the importance of highly oxidized, reactive organics in air-surface processes (whether atmosphere-biosphere exchange or aerosols), as well as the extent of interactions of anthropogenic and biogenic emissions and the resulting impact on atmospheric organic chemistry. PMID:26862779

  2. Equilibrium Chemistry Calculations for Model Hot-Jupiter Atmospheres

    NASA Astrophysics Data System (ADS)

    Blumenthal, Sarah; Harrington, Joseph; Bowman, M. Oliver; Blecic, Jasmina

    2014-11-01

    Every planet in our solar system has different elemental abundances from our sun's. It is thus necessary to explore a variety of elemental abundances when investigating exoplanet atmospheres. Composition is key to unraveling a planet's formation history and determines the radiative behavior of an atmosphere, including its spectrum (Moses et al. 2013). We consider here two commonly discussed situations: [C]/[O] > 1 and 10x and 100x heavy-element enrichment. For planets above 1200 K, equilibrium chemistry is a valid starting point in atmospheric analysis. For HD 209458b, this assumption was verified by comparing the results of a robust kinetics code (non-ideal behavior) to the results of an equilibrium chemistry code (ideal behavior). Both codes output similar results for the dayside of the planet (Agundez et al. 2012). Using NASA's open-source Chemical Equilibrium Abundances code (McBride and Gordon 1996), we calculate the molecular abundances of species of interest across the dayside of model planets with a range of: elemental abundance profiles, degree of redistribution, relevant substellar temperatures, and pressures. We then explore the compositional gradient of each model planet atmosphere layer using synthetic abundance images of target spectroscopic species (water, methane, carbon monoxide). This work was supported by the NASA Planetary Atmospheres grant NNX12AI69G and NASA Astrophysics Data Analysis Program NNX13AF38G.

  3. A new mechanism for regional atmospheric chemistry modeling

    NASA Astrophysics Data System (ADS)

    Stockwell, William R.; Kirchner, Frank; Kuhn, Michael; Seefeld, Stephan

    1997-11-01

    A new gas-phase chemical mechanism for the modeling of regional atmospheric chemistry, the "Regional Atmospheric Chemistry Mechanism" (RACM) is presented. The mechanism is intended to be valid for remote to polluted conditions and from the Earth's surface through the upper troposphere. The RACM mechanism is based upon the earlier Regional Acid Deposition Model, version 2 (RADM2) mechanism [Stockwell et al., 1990] and the more detailed Euro-RADM mechanism [Stockwell and Kley, 1994]. The RACM mechanism includes rate constants and product yields from the most recent laboratory measurements, and it has been tested against environmental chamber data. A new condensed reaction mechanism is included for biogenic compounds: isoprene, α-pinene, and d-limonene. The branching ratios for alkane decay were reevaluated, and in the revised mechanism the aldehyde to ketone ratios were significantly reduced. The relatively large amounts of nitrates resulting from the reactions of unbranched alkenes with NO3 are now included, and the production of HO from the ozonolysis of alkenes has a much greater yield. The aromatic chemistry has been revised through the use of new laboratory data. The yield of cresol production from aromatics was reduced, while the reactions of HO, NO3, and O3 with unsaturated dicarbonyl species and unsaturated peroxynitrate are now included in the RACM mechanism. The peroxyacetyl nitrate chemistry and the organic peroxy radical-peroxy radical reactions were revised, and organic peroxy radical +NO3 reactions were added.

  4. Chemistry of the atmospheres of Mars and Venus

    NASA Astrophysics Data System (ADS)

    Krasnopolsky, Vladimir

    Photochemistry of the Martian lower and middle atmosphere involves CO2 and its products (CO, O, O _{2}, O _{3}, O _{2}( (1) Delta _{g})) and H _{2}O and its products (H, OH, HO _{2}, H _{2}O _{2}, H _{2}). This photochemistry is comparatively simple and well studied in the laboratory. However, all global-mean models predict CO abundances that are significantly smaller than the observed values. Heterogeneous loss of odd hydrogen on water ice aerosol cannot solve the problem. Another possibility is a significant decrease in photolysis of H _{2}O near 190 nm at low temperatures. Combination of the significant obliquity with the elliptic orbit results in strong seasonal, latitudinal, and local time variations in the comparatively thin atmosphere of Mars. These variations are challenging in both observation and modeling. While some aspects of these variations were simulated by 1D models, the best tool for their study is photochemical general circulation models. The LMD GCM (Lefevre and Forget 2009 and references therein) accounts for the martian photochemistry in full and reproduces with reasonable accuracy the observed variations of the main photochemical tracers (O _{3}, O _{2}( (1) Delta _{g}), and H _{2}O _{2}). Ground-based observations of methane after 2006 gave only upper limits and generally do not contradict the TLS/Curiosity non-detection. However, significant variations of methane are not supported by photochemistry. Chemistry of Venus’ atmosphere involves seven elements (O, C, S, H, Cl, N, F) and the very dense and hot lower atmosphere. Formation of the sulfuric acid clouds is the main feature of photochemistry of the middle atmosphere. This process greatly reduces the abundances of H _{2}O and SO _{2} above 70 km that become very sensitive to small variations of eddy diffusion and the H _{2}O/SO _{2} ratio in the cloud layer. The observed an order of magnitude variations are therefore readily explained and do not require exotic volcanoes. Chlorine

  5. The Department of Energy's Atmospheric Chemistry Program: A critical review

    SciTech Connect

    Not Available

    1991-01-01

    In response to a request from the Department of Energy's (DOE) Office of Health and Environmental Research (OHER), the Committee on Atmospheric Chemistry has reviewed OHER's Atmospheric Chemistry Program (ACP). This report contains the committee's evaluation and critique arising from that review. The review process included a two-day symposium held at the National Academy of Sciences on September 25 and 26, 1990, that focused on presenting the ACP's current components, recent scientific accomplishments, and scientific plans. Following the symposium, committee members met in a one-day executive session to formulate and outline this report. In undertaking this review, OHER and ACP management requested that the committee attempt to answer several specific questions involving the program's technical capability and productivity, its leadership and organization, and its future direction. These questions are given in the Appendix. This report represents the committee's response to the questions posed in the Appendix. Chapter I explores the committee's view of the role that atmospheric chemistry could and should assume within the DOE and its prospective National Energy Strategy. Chapter 2 assesses the current ACP, Chapter 3 presents recommendations for revising and strengthening it, and Chapter 4 restates the committee's conclusions and recommendations.

  6. Role of Double Hydrogen Atom Transfer Reactions in Atmospheric Chemistry.

    PubMed

    Kumar, Manoj; Sinha, Amitabha; Francisco, Joseph S

    2016-05-17

    Hydrogen atom transfer (HAT) reactions are ubiquitous and play a crucial role in chemistries occurring in the atmosphere, biology, and industry. In the atmosphere, the most common and traditional HAT reaction is that associated with the OH radical abstracting a hydrogen atom from the plethora of organic molecules in the troposphere via R-H + OH → R + H2O. This reaction motif involves a single hydrogen transfer. More recently, in the literature, there is an emerging framework for a new class of HAT reactions that involves double hydrogen transfers. These reactions are broadly classified into four categories: (i) addition, (ii) elimination, (iii) substitution, and (iv) rearrangement. Hydration and dehydration are classic examples of addition and elimination reactions, respectively whereas tautomerization or isomerization belongs to a class of rearrangement reactions. Atmospheric acids and water typically mediate these reactions. Organic and inorganic acids are present in appreciable levels in the atmosphere and are capable of facilitating two-point hydrogen bonding interactions with oxygenates possessing an hydroxyl and/or carbonyl-type functionality. As a result, acids influence the reactivity of oxygenates and, thus, the energetics and kinetics of their HAT-based chemistries. The steric and electronic effects of acids play an important role in determining the efficacy of acid catalysis. Acids that reduce the steric strain of 1:1 substrate···acid complex are generally better catalysts. Among a family of monocarboxylic acids, the electronic effects become important; barrier to the catalyzed reaction correlates strongly with the pKa of the acid. Under acid catalysis, the hydration of carbonyl compounds leads to the barrierless formation of diols, which can serve as seed particles for atmospheric aerosol growth. The hydration of sulfur trioxide, which is the principle mechanism for atmospheric sulfuric acid formation, also becomes barrierless under acid catalysis

  7. Cassini atmospheric chemistry mapper. Volume 1. Investigation and technical plan

    NASA Technical Reports Server (NTRS)

    Smith, William Hayden; Baines, Kevin Hays; Drossart, Pierre; Fegley, Bruce; Orton, Glenn; Noll, Keith; Reitsema, Harold; Bjoraker, Gordon L.

    1990-01-01

    The Cassini Atmospheric Chemistry Mapper (ACM) enables a broad range of atmospheric science investigations for Saturn and Titan by providing high spectral and spatial resolution mapping and occultation capabilities at 3 and 5 microns. ACM can directly address the major atmospheric science objectives for Saturn and for Titan, as defined by the Announcement of Opportunity, with pivotal diagnostic measurements not accessible to any other proposed Cassini instrument. ACM determines mixing ratios for atmospheric molecules from spectral line profiles for an important and extensive volume of the atmosphere of Saturn (and Jupiter). Spatial and vertical profiles of disequilibrium species abundances define Saturn's deep atmosphere, its chemistry, and its vertical transport phenomena. ACM spectral maps provide a unique means to interpret atmospheric conditions in the deep (approximately 1000 bar) atmosphere of Saturn. Deep chemistry and vertical transport is inferred from the vertical and horizontal distribution of a series of disequilibrium species. Solar occultations provide a method to bridge the altitude range in Saturn's (and Titan's) atmosphere that is not accessible to radio science, thermal infrared, and UV spectroscopy with temperature measurements to plus or minus 2K from the analysis of molecular line ratios and to attain an high sensitivity for low-abundance chemical species in the very large column densities that may be achieved during occultations for Saturn. For Titan, ACM solar occultations yield very well resolved (1/6 scale height) vertical mixing ratios column abundances for atmospheric molecular constituents. Occultations also provide for detecting abundant species very high in the upper atmosphere, while at greater depths, detecting the isotopes of C and O, constraining the production mechanisms, and/or sources for the above species. ACM measures the vertical and horizontal distribution of aerosols via their opacity at 3 microns and, particularly, at 5

  8. The DaVinci Project: Multimedia in Art and Chemistry.

    ERIC Educational Resources Information Center

    Simonson, Michael; Schlosser, Charles

    1998-01-01

    Provides an overview of the DaVinci Project, a collaboration of students, teachers, and researchers in chemistry and art to develop multimedia materials for grades 3-12 visualizing basic concepts in chemistry and visual art. Topics addressed include standards in art and science; the conceptual framework for the project; and project goals,…

  9. Equilibrium and Disequilibrium Chemistry in Evolved Exoplanet Atmospheres

    NASA Astrophysics Data System (ADS)

    Hu, Renyu

    2015-08-01

    It has been found that sub-Neptune-sized planets, although not existing in our Solar System, are ubiquitous in our interstellar neighborhood. This revelation is profound because, due to their special sizes and proximity to their host stars, Neptune- and sub-Neptune-sized exoplanets may have highly evolved atmospheres. I will discuss helium-dominated atmospheres as one of the outcomes of extensive atmospheric evolution on warm Neptune- and sub-Neptune-sized exoplanets. Due to depleted hydrogen abundance, the dominant carbon and oxygen species may not be methane or water on these evolved planets. Equilibrium and disequilibrium chemistry models are used to compute the molecular compositions of the atmospheres and their spectral features. Applications to GJ 436 b, HD 97658 b, and other Neptune- and sub-Neptune-sized exoplanets will be discussed. As the observations to obtain the spectra of these planets continue to flourish, we will have the opportunity to study unconventional atmospheric chemical processes and test atmosphere evolution theories.

  10. The Workshop Chemistry Project: Peer-Led Team Learning.

    ERIC Educational Resources Information Center

    Gosser, David K., Jr.; Roth, Vicki

    1998-01-01

    Describes the Workshop Chemistry project, a coalition of faculty, students, and learning specialists, and the development of a peer-led team-learning model for teaching and learning chemistry. The model includes freedom to discuss and debate chemistry in a challenging yet supportive environment, connection to mentors, and the power of working as…

  11. Spectroscopy and chemistry of the atmosphere of Uranus

    NASA Technical Reports Server (NTRS)

    Fegley, Bruce, Jr.; Gautier, Daniel; Owen, Tobias; Prinn, Ronald G.

    1991-01-01

    A comprehensive review of the chemistry and spectroscopy of the Uranian atmosphere is presented by means of earth-based, earth-orbital, and Voyager 2 observations covering the UV, visible, infrared, and radio wavelength regions. It is inferred from these observations, in concert with the average density of about 1.3 g/cu cm, that the Uranian atmosphere is enriched in heavy elements relative to solar composition. Pre-Voyager earth-based observations of CH4 bands in the visible region and Voyager radio occultation data imply a CH4/H2 volume mixing ratio of about 2 percent corresponding to an enrichment of approximately 24 times the solar value of 0.000835. In contrast to CH4, microwave observations indicate an apparent depletion of NH3 in the 155-to-200-K region of the atmosphere by 100 to 200 times relative to the solar NH3/H2 mixing ratio of -0.000174. It is suggested that the temporal and latitudinal variations deduced for the NH3/H2 mixing ratio in this region of the Uranian atmosphere are due to atmospheric circulation effects.

  12. Geospatial visualization of atmospheric chemistry satellite data using Google Earth

    NASA Astrophysics Data System (ADS)

    Burke, John

    2008-08-01

    Earth observation satellites employ various types of remote-sensing instruments to peer into the secrets of the atmosphere. Many of these instruments collect two-dimensional data stored as raster images which can be easily georeferenced and overlaid onto a virtual globe, with stunning results. However, certain instruments collect threedimensional science data which can pose a significant challenge for visualization efforts. The Tropospheric Emission Spectrometer (TES) is such an instrument which collects scientific data about atmospheric chemistry and stores the outputs in an Oracle database. With some imaginative programming, the data is transformed into interesting and information-packed visualizations using shell scripts, SQL scripts and Oracle stored procedures to yield Google Earthformatted files. This Google Earth content is hosted on the TES external web site for use by the public.

  13. Putting a Human Face on Chemistry: A Project for Liberal Arts Chemistry.

    ERIC Educational Resources Information Center

    Kriz, George; Popejoy, Kate

    A collaborative project in liberal arts chemistry, involving faculty in chemistry and science education, is described. The project includes various components: an introductory test (DAST) to examine students' perceptions of scientists, a group library research exercise, oral and written presentation of the results of the library research, a…

  14. EDITORIAL: Ice in the environment: connections to atmospheric chemistry Ice in the environment: connections to atmospheric chemistry

    NASA Astrophysics Data System (ADS)

    McNeill, V. Faye; Hastings, Meredith G.

    2008-12-01

    Ice in the environment, whether in the form of ice particles in clouds or sea ice and snow at the Earth's surface, has a profound influence on atmospheric composition and climate. The interaction of trace atmospheric gases with snow and sea ice surfaces largely controls atmospheric composition in polar regions. The heterogeneous chemistry of ice particles in clouds also plays critical roles in polar stratospheric ozone depletion and in tropospheric chemistry. A quantitative physical understanding of the interactions of snow and ice with trace gases is critical for predicting the effects of climate change on atmospheric composition, for the interpretation of ice core chemical records, and for modeling atmospheric chemistry. The motivation behind this focus issue of Environmental Research Letters (ERL), and the special session at the Fall 2007 meeting of the American Geophysical Union that generated it, was to enhance communication and interactions among field and laboratory scientists and modelers working in this area. Members of these three groups are each working toward a mutual goal of understanding and quantifying the connections between the chemistry of snow and ice in the environment and atmospheric composition, and communication and collaboration across these traditional disciplinary boundaries pose a challenge for the community. We are pleased to present new work from several current leaders in the field and laboratory communities in this focus issue. Topics include the interaction of organics and mercury with snow and ice surfaces, halogen activation from halide ice, and the emissions of reactive nitrogen oxides from snow. Novel experimental techniques are presented that make progress towards overcoming the experimental challenges of quantifying the chemistry of realistic snow samples and ice chemistry at temperatures relevant to the polar boundary layer. Several of the papers in this issue also touch on one of the significant gaps in our current

  15. The global change research center atmospheric chemistry model

    SciTech Connect

    Moraes, F.P. Jr.

    1995-01-01

    This work outlines the development of a new model of the chemistry of the natural atmosphere. The model is 2.5-dimensional, having spatial coordinates height, latitude, and, the half-dimension, land and ocean. The model spans both the troposphere and stratosphere, although the troposphere is emphasized and the stratosphere is simple and incomplete. The chemistry in the model includes the O{sub x}, HO{sub x}, NO{sub x}, and methane cycles in a highly modular fashion which allows model users great flexibility in selecting simulation parameters. A detailed modeled sensitivity analysis is also presented. A key aspect of the model is its inclusion of clouds. The model uses current understanding of the distribution and optical thickness of clouds to determine the true radiation distribution in the atmosphere. As a result, detailed studies of the radiative effects of clouds on the distribution of both oxidant concentrations and trace gas removal are possible. This work presents a beginning of this study with model results and discussion of cloud effects on the hydroxyl radical.

  16. The nitrate radical: Physics, chemistry, and the atmosphere

    NASA Astrophysics Data System (ADS)

    Wayne, R. P.; Barnes, I.; Biggs, P.; Burrows, J. P.; Canosa-Mas, C. E.; Hjorth, J.; Le Bras, G.; Moortgat, G. K.; Perner, D.; Poulet, G.; Restelli, G.; Sidebottom, H.

    This review surveys the present state of knowledge of the nitrate (NO 3 radical. Laboratory data on the physics and chemistry of the radical and atmospheric determination of the concentrations of the radical are both considered. One aim of the review is to highlight the relationship between the laboratory and the atmospheric studies. Although the emphasis of the review is on gas-phase processes, relevant studies conducted in condensed phases are mentioned because of their potential importance in the interpretation of cloud and aerosol chemistry. The spectroscopy, structure, and photochemistry of the radical are examined. Here, the object is to establich the spectroscopic basis for detection of the radical and measurement of its concentration in the laboratory and in the atmosphere. Infrared, visible, and paramagnetic resonance spectra are considered. An important quantity discussed is the absorption cross section in the visible region, which is required for quantitative measurements. Interpretation of the spectroscopic features requires an understanding of the geometrical and electronic structure of the radical in its ground and excited states; there is still some controversy about the groundstate geometry, but the most recent experimental evidence 9eg from laser induced fluorescence) and theoretical calculations suggest that the radical has D3h symmetry. Photodissociation of the radical is important in the atmosphere, and the product channels, quantum yields, and dissociation dynamics are discussed. A short examination of the thermodynamics (heat and entropy of formation) of the radical is presented. The main exposition of laboratory studies of the chemistry of the nitrate radical is preceded by a consideration of the techniques used for kinetic and mechanistic studies. Methods for the generation and detection of the radical and the kinetic tools employed are all presented. The exact nature of the technique used in individual studies has some relevance to the way

  17. Portsmouth Atmospheric Science School (PASS) Project

    NASA Technical Reports Server (NTRS)

    Coleman, Clarence D.; Hathaway, Roger (Technical Monitor)

    2002-01-01

    The Portsmouth Atmospheric Science School Project (PASS) Project was granted a one-year no cost extension for 2001-2002. In year three of the project, objectives and strategies were modified based on the previous year-end evaluation. The recommendations were incorporated and the program was replicated within most of the remaining elementary schools in Portsmouth, Virginia and continued in the four middle schools. The Portsmouth Atmospheric Science School Project is a partnership, which includes Norfolk State University, Cooperating Hampton Roads Organizations for Minorities in Engineering (CHROME), NASA Langley Research Center, and the City of Portsmouth, Virginia Public Schools. The project seeks to strengthen the knowledge of Portsmouth Public Schools students in the field of atmospheric sciences and enhance teacher awareness of hands on activities in the atmospheric sciences. The project specifically seeks to: 1) increase the interest and participation of elementary and middle school students in science and mathematics; 2) strengthen existing science programs; and 3) facilitate greater achievement in core subjects, which are necessary for math, science, and technical careers. Emphasis was placed on providing training activities, materials and resources for elementary students (grades 3 - 5) and middle school students (grades 6 - 8), and teachers through a CHROME club structure. The first year of the project focused on introducing elementary students to concepts and activities in atmospheric science. Year two of the project built on the first year's activities and utilizes advanced topics and activities appropriate for middle school students. During the third year of the project, in addition to the approaches used in years one and two, emphasis was placed on activities that enhanced the Virginia Standards of Learning (SOL).

  18. STREAMWATER ACID-BASED CHEMISTRY AND CRITICAL LOADS OF ATMOSPHERIC SULFUR DEPOSITION IN SHENANDOAH NATIONAL PARK, VIRGINIA

    EPA Science Inventory

    A modeling study was conducted to evaluate the acid-base chemistry of streams within Shenandoah National Park, Virginia and to project future responses to sulfur (S) and nitrogen (N) atmospheric emissions controls. Many of the major stream systems in the Park have acid neutraliz...

  19. Modeling of Large Methane Releases and their affect on the Chemistry of the Atmosphere

    NASA Astrophysics Data System (ADS)

    Bergmann, D. J.; Cameron-Smith, P. J.; Elliot, S.; Reagan, M. T.; Maltrud, M. E.

    2009-12-01

    A vast quantity of methane is locked in solid phase as methane clathrates in ocean sediments (as much carbon as all other fossil fuels combined). Rapid destabilization of the clathrates due to climate warming would significantly increase methane emissions from the ocean. This would result in a number of affects including strong greenhouse heating, increased surface ozone, reduced stratospheric ozone, and intensification of the ozone hole. Many of the affects in the chemistry of the atmosphere are non-linear and difficult to estimate without a detailed model. As part of the DOE IMPACTS project on abrupt climate change we have used our 3D global atmospheric chemistry model (IMPACT) to take a first look at some of these affects. This model includes detailed chemistry of the troposphere (including isoprene and other hydrocarbons) and the stratosphere (including the important chlorine and bromine compounds). We ran the model at 4x5 degree resolution with methane simply scaled to present day emissions. We show results for 1x, 2x, 10x, 100x, and 1000x emission scenarios. We analyzed the results after the simulations have reached steady state (many years of simulation) and show the affect of these large releases on tropospheric air quality, the “health” of the stratosphere, and greenhouse heating. Substantial increases were seen in atmospheric methane lifetime, a positive feedback, due to the increased methane reducing the OH concentration. In the future we will couple our atmospheric chemistry to a complete Earth system model (based on CCSM) for methane including ocean ecosystem, ocean sediment and boreal land models to give more accurate estimates of the emission term and to look at the full system response.

  20. Pilot Project for Chemistry Teaching in Asia.

    ERIC Educational Resources Information Center

    United Nations Educational, Scientific, and Cultural Organization, Bangkok (Thailand).

    The major portion of this publication is devoted to the presentation of 20 chemistry experiments dealing with corrosion of metals. The experiments are intended for high school level students or for chemistry teachers for demonstration purposes. Diagrams and illustrations accompany the written directions. Also included in this publication are…

  1. Nitrate chemistry in the snow and atmosphere at Summit, Greenland

    NASA Astrophysics Data System (ADS)

    Fibiger, D. L.; Hastings, M. G.; Dibb, J. E.; Nenes, A.; Chen, D.

    2013-12-01

    Atmospheric nitrate deposition to snow surfaces results from reactions of NOx (NO + NO2) with oxidants to produce HNO3. There has been enormous interest in using the isotopic composition of nitrate in ice cores to trace past NOx chemistry and sources. With the rapid cycling of NO and NO2, the oxygen isotopic signal reflects the oxidants that NOx reacts with to form nitrate, while the nitrogen isotopes could contain information about the NOx sources. In two spring/summer field seasons at Summit, Greenland (May-June 2010 and 2011), surface snow was collected at high time resolution and was measured for the complete N and O isotopic composition of nitrate. The oxygen isotopes (δ18O and Δ17O = δ17O - 0.52*δ18O) display the same very strong linear relationship (Δ17O = 0.46 * δ18O - 6.9, R2 = 0.9) in both seasons. This relationship indicates that there is very little photolysis of the nitrate at Summit and an unaltered nitrate signal is preserved in the snowpack. In addition, a suite of atmospheric measurements was made at Summit and none of the constituents measured show any correlation with concentration or isotopes of nitrate in the snow. This indicates that local chemistry is not contributing significantly to the nitrate in the snow. The combination of nitrogen and oxygen isotopes provides a richer picture of the data. There are three nitrate signatures that contribute to total nitrate deposition to Summit in both seasons. These sources can be described by the following isotopic compositions: δ15N, Δ17O, δ18O (per mil vs. air N2 or VSMOW): (1) -8, 27, 74 (2) 6, 40, 100 and (3) 16, 0, 23. While the same three nitrate sources are contributing in the two years, there is a very different balance of importance in 2010 compared to 2011. With limited source δ15N data it is difficult to assign each point to a specific NOx source, however the complete isotopic composition, atmospheric measurements and differences between the two seasons allow for tentative source

  2. An Atmospheric Instrument Development Outreach Project

    NASA Astrophysics Data System (ADS)

    Guerra, David; Cordella, Nick; Bracy, Sue

    2002-04-01

    In an effort to cultivate the interest in atmospheric science of middle school students, we have established a long-term outreach program in which students become active participants in an instrument development study. This project was motivated by the low cost, $20.00, hand-held haze detector (HHHD) developed by Forrest Mims III and the capabilities of the instruments located 5 miles away as part of the Saint Anselm Atmospheric Sensing Experiment (SAASE). The focus of the project, for the past two academic years, has been the development and data collected with two different HHHDs, operated by eighth graders from Mountain View Middle School (MVMS). This data is then compared to the solar irradiance measurements made with SAASE's automated multifilter shadow band radiometer (MFSBR). This type of outreach project not only teaches students about the atmosphere but also the process of instrument development and the creative aspects of science.

  3. Hydrogen atom initiated chemistry. [chemical evolution in planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Hong, J. H.; Becker, R. S.

    1979-01-01

    H Atoms have been created by the photolysis of H2S. These then initiated reactions in mixtures involving acetylene-ammonia-water and ethylene-ammonia-water. In the case of the acetylene system, the products consisted of two amino acids, ethylene and a group of primarily cyclic thio-compounds, but no free sulfur. In the case of the ethylene systems, seven amino acids, including an aromatic one, ethane, free sulfur, and a group of solely linear thio-compounds were produced. Total quantum yields for the production of amino acids were about 3 x 10 to the -5th and about 2 x 10 to the -4th with ethylene and acetylene respectively as carbon substrates. Consideration is given of the mechanism for the formation of some of the products and implications regarding planetary atmosphere chemistry, particularly that of Jupiter, are explored.

  4. TROPOLITE, on the path of atmospheric chemistry made simple

    NASA Astrophysics Data System (ADS)

    Maresi, Luca; Van Der Meulen, Wencke; Vink, Rob

    2014-10-01

    Accurate, reliable and stable long term measurements of Earth's Atmospheric Chemistry from Space are currently done by complex instruments, whose mass is in excess of 100 Kg. TROPOMI is the more recent instrument being developed jointly by ESA and NSO and due for launch in 2015. TROPOMI, consisting of four spectrometers ranging from UV to SWIR, is paving the way to the development of high performance spectrometers that will compose the backbone of the European Copernicus system. The objective of TROPOMI is to measure trace gases with an accuracy one order of magnitude better of what is currently done from Space. While teams of engineers are still busy finalizing TROPOMI, ESA, NSO, and TNO have launched an initiative along a different development axis: to explore the possibility of a lighter version of TROPOMI, to address a market valuing a cost effective instrument for Atmospheric Chemistry. TROPOLITE, as it is dubbed, leverages on all the technology developments and the lessons learnt from TROPOMI, but with the clear objective of a design to cost solution. Furthermore, mass and power of the instrument shall be within the envelope of a payload of a small satellite, namely 20kg and 30W and possibly within a volume of 20 x 20 x 40 cm3. The scope of TROPOLITE is to address a larger user base that is interested in an affordable instrument to perform from a small satellite some specific tasks relevant to Air Quality and/or Climate. The paper, after a short overview of the TROPOMI design and current status, presents the design philosophy of TROPOLITE, and shows what are the technologies and processes stemming from the experience gained with TROPOMI that make possible a simplified, but still very performing, version of TROPOMI. A comparison in terms of performance and functionalities of the two instruments is discussed. Finally, the development plan from the current development status of TROPOLITE up to Qualification Model is presented.

  5. The Unsolved Mysteries of Atmospheric Chemistry for High School Students and Teachers

    NASA Astrophysics Data System (ADS)

    Simonich, S. L.

    2011-12-01

    The grant "CAREER: New Molecular Markers of Asian Air Emissions - Anthropogenic Semi-Volatile Organic Compounds" (ATM-0239823) was funded by NSF from 2003-2008. The CAREER proposal described the integration of research and outreach education activities in the field of atmospheric chemistry, specifically atmospheric measurements and atmospheric transport. The primary objective of the research was to identify anthropogenic semi-volatile organic compounds (SOCs) that could be used as molecular markers for Asian air emissions and trans-Pacific atmospheric transport. The outreach education activity was integrated with the research by developing curriculum to introduce underrepresented minority high school students, and their teachers, to atmospheric chemistry and atmospheric measurements through Oregon State University's National Institute of Environmental Health Sciences funded Hydroville Curriculum Project (http://www.hydroville.org/iaq_resources). A curriculum was developed to allow students to assume the role of "Air Quality Scientist" and measure air temperature, air flow, relative humidity, CO, CO2, O3, and volatile organic compounds in out-door and in-door air. The students gained an understanding of atmospheric transport and compared measured concentrations to recommended guidelines. In addition, the outreach education activities included the development of the "Unsolved Mysteries of Human Health" website (http://www.unsolvedmysteries.oregonstate.edu/), including a specific module on the research conducted under the CAREER grant (http://www.unsolvedmysteries.oregonstate.edu /Gas-Chromatography-Mass-Spectrometry-Overview). The PI of the CAREER proposal, Dr. Staci Massey Simonich, is now a full professor at Oregon State University. To date, she has published over 50 peer-review journal articles, as well as mentored 9 undergraduate students, 20 graduate students, 3 post-doctoral scholars, and 3 international visiting scientists in her laboratory.

  6. Laboratory studies of low temperature rate coefficients: The atmospheric chemistry of the outer planets

    NASA Technical Reports Server (NTRS)

    Leone, Stephen R.

    1992-01-01

    The purpose of the project is to perform laboratory measurements of reaction rate coefficients at low temperature. The reactions and temperatures of interest are those that are important in the chemistry of the hydrocarbon rich atmospheres of the outer planets and their satellites. In this stage of the study we are investigating reactions of ethynyl radicals, C2H, with acetylene (C2H2), methane (CH4), and hydrogen (H2). In the previous status report from 24 Jan. 1992, we reported on the development of the experimental apparatus and the first, preliminary data for the C2H + C2H2 reaction.

  7. "The Chemicals Project": Connecting General Chemistry to Students' Lives

    NASA Astrophysics Data System (ADS)

    Stout, Roland

    2000-10-01

    "The Chemicals Project" described here strives to bring freshman chemistry alive for students by emphasizing its connection to the real world and to their own lives and experiences. Its major assignments deal with chemical phobias, recognizing the chemicals found in everyday life and chemical hazards (using Material Data Safety Sheets). The project is described in a cooperative learning format, employs portfolio grading, and includes a significant writing component. Ways of linking this project with the course lecture and student evaluations of the project are described. The bottom line: pre- and post-testing shows that it works. The Chemicals Project brings chemistry alive for students.

  8. A Chemistry Laboratory Project to Develop Thinking and Writing Skills.

    ERIC Educational Resources Information Center

    Goodman, W. Daniel; Bean, John C.

    1983-01-01

    Describes a method for conducting a sophomore organic chemistry laboratory which included integrating projects with a writing task involving peer group interaction. Also includes background/theory, chemistry tasks, writing tasks, and evaluation. Included in appendices are an analytic worksheet and grading scale. (JN)

  9. Solar Energy Project, Activities: Chemistry & Physics.

    ERIC Educational Resources Information Center

    Tullock, Bruce, Ed.; And Others

    This guide contains lesson plans and outlines of science activities which present concepts of solar energy in the context of chemistry and physics experiments. Each unit presents an introduction to the unit; objectives; required skills and knowledge; materials; method; questions; recommendations for further work; and a teacher information sheet.…

  10. Ion Chemistry and Dust Aerosols in the Martian Lower Atmosphere

    NASA Astrophysics Data System (ADS)

    Sheel, Varun; Haider, Syed A.

    2012-07-01

    Models of the daytime upper ionosphere and nighttime models have been able to explain some of the observations of the Martian atmosphere. However, not much attention has been paid to the ionosphere below 100 km. We have developed a detailed chemistry model of 35 ions and 12 neutral species with galactic cosmic rays as the primary source of ionization to calculate the densities of ions in the daytime lower atmosphere of Mars (Haider et al., 2008). The chemical model couples various processes through 101 chemical reactions. We do a quantitative comparison between various production and loss processes, in order to tag each of them with their relative importance in determining the ion densities. Impact of galactic cosmic rays initially produces CO_{2}^{+} and O_{2}^{+} ions, but the ion chemistry eventually leads to the dominance of hydrated positive and negative ions with maximum densities of about 10^{3} cm^{-3}. It is found that out of all the processes included in the model, the most important process is the ion-neutral collisions wherein the reaction of H_{3}O^{+}(H_{2}O)_{2,3} with water and air molecules having the highest rates of ˜10^5 cm^{-3} s^{-1} (Sheel et al., PSS, in press). These ions can charge dust aerosols in the lower ionosphere of Mars. Periodical massive dust storms with high surface winds disturb surface sediments and lift large amounts of dust into the atmosphere. We have extended the ion model to study the effect of dust on ions in the troposphere of Mars. The dust vertical profile, used as an input to our model, is calculated using the Conrath parametrisation and constrained with dust opacities observed by THEMIS onboard the Mars Odyssey. We observe that the major positive and negative hydrated ions decrease by upto two orders of magnitude in the presence of dust (Haider at al, 2010). These results will be presented and dust variability observed by MGS and Mars Odyssey will also be discussed in the talk. Our calculations provide an initial

  11. Microwave Studies of Chemistry of the Middle Atmosphere

    NASA Astrophysics Data System (ADS)

    Sandor, Brad J.

    The purpose of this study has been to investigate O_3 chemistry in Earth's middle atmosphere. The NRAO 12-meter radio telescope at Kitt Peak, AZ was used to observe lambda = 1 mm emission spectra of trace species at altitudes 50 -70 km. Brightness of the emission lines was used to determine abundance of the emitting species, and shapes of the pressure broadened lines were used to obtain altitude resolution of these abundances. Observations of ^{18}O^{16}O, CO, and O_3 were used to establish a calibration appropriate for atmospheric observations with a telescope primarily used for astronomical work. Diurnal variation of O_2(^1 Delta_{g}) was observed and compared with photochemical model results. Observed O_2(^1Delta_ {g}) abundances were 20% higher than model abundances, and model results can be brought into agreement with observations by reducing the rate coefficient for O_2(^1Delta_ {g}) quenching by 20% below the accepted value. The behavior of O_2(^1Delta _{g}) through the afternoon and evening was observed to agree with model calculations. Symmetric and asymmetric isotopomers of ^{50}O_3 were observed. Previous workers have found large, highly variable, and unexplained enhancements of ^{50}O _3 in the stratosphere. We extend the range of observations to the mesosphere. Significant variability in the abundance of the asymmetric isotopomer was observed. Diurnal variations of HO_2 were observed in conjunction with H_2O and O_3. Comparisons were made with photochemical model results. At mid-day HO _2 abundances were observed to be ~40% higher than model predictions. Model results for this time period can be brought into agreement with observations by reducing the rate coefficient for rm HO_2 + O--> OH + O _2 by 40%. Observed HO_2 altitude profiles in the early morning, late afternoon, and early evening are very different from model predictions.

  12. Projections of atmospheric radiocarbon content to 2100

    NASA Astrophysics Data System (ADS)

    Graven, Heather

    2014-05-01

    The radiocarbon content of atmospheric CO2 has undergone dramatic changes over the past century. Radiocarbon in CO2 has been diluted by the combustion of 14C-free fossil fuels since the industrial revolution, causing a slow decline in the relative abundance of 14C to total carbon (Δ14C) in the early 1900s. This decline was interrupted by nuclear weapons testing in the 1950s and 60s, which nearly doubled the atmospheric inventory of 14C. Following the extraordinary rise in radiocarbon content, a quasi-exponential decrease was observed as excess radiocarbon was assimilated by carbon reservoirs in the ocean and on land. Recently, fossil fuel emissions have once again become the dominant influence on the long-term trend in Δ14C of CO2. This presentation will investigate the trajectory of atmospheric Δ14C to 2100 in relation to the Representative Concentration Pathways (RCPs) using a simple carbon cycle model. In all scenarios, Δ14C of CO2 is projected to drop below the zero per mil level in the next decade. Simulated atmospheric Δ14C is lower than -200 per mil in 2100 in the scenario with the largest growth in fossil fuel emissions, while the most ambitious emission reductions are projected to sustain Δ14C near zero per mil. The presentation will discuss the implications of these changes in atmospheric composition on isotopic disequilibria and net fluxes of radiocarbon between different reservoirs, including the sensitivity of atmospheric Δ14C to fossil fuel emissions on global and regional scales.

  13. Urban Climate Effects on Air Pollution and Atmospheric Chemistry

    NASA Astrophysics Data System (ADS)

    Rasoul, Tara; Bloss, William; Pope, Francis

    2016-04-01

    Tropospheric ozone, adversely affects the environment and human health. The presence of chlorine nitrate (ClNO2) in the troposphere can enhance ozone (O3) formation as it undergoes photolysis, releasing chlorine reactive atoms (Cl) and nitrogen dioxide (NO2), both of which enhance tropospheric ozone formation. The importance of new sources of tropospheric ClNO2 via heterogeneous processes has recently been highlighted. This study employed a box model, using the Master Chemical Mechanism (MCM version 3.2) to assess the effect of ClNO2 on air quality in urban areas within the UK. The model updated to include ClNO2 production, photolysis, a comprehensive parameterisation of dinitrogen pentoxide (N2O5) uptake, and ClNO2 production calculated from bulk aerosol composition. The model simulation revealed the presence of ClNO2 enhances the formation of NO2, organic peroxy radical (CH3O2), O3, and hydroxyl radicals (OH) when compared with simulations excluding ClNO2. In addition, the study examined the effect of temperature variation upon ClNO2 formation. The response of ClNO2 to temperature was analysed to identify the underlying drivers, of particular importance when assessing the response of atmospheric chemistry processes under potential future climates.

  14. Implementing a Student-Designed Green Chemistry Laboratory Project in Organic Chemistry

    ERIC Educational Resources Information Center

    Graham, Kate J.; Jones, T. Nicholas; Schaller, Chris P.; McIntee, Edward J.

    2014-01-01

    A multiweek organic chemistry laboratory project is described that emphasizes sustainable practices in experimental design. An emphasis on student-driven development of the project is meant to mirror the independent nature of research. Students propose environmentally friendly modifications of several reactions. With instructor feedback, students…

  15. Incorporating Student-Designed Research Projects in the Chemistry Curriculum

    ERIC Educational Resources Information Center

    Iimoto, Devin S.; Frederick, Kimberley A.

    2011-01-01

    Although many chemistry students at small liberal arts colleges participate in undergraduate research projects with faculty members, they do not get much experience framing their own research questions and designing their own projects, which is an important part of science. We have implemented a developmental process to help students design and…

  16. A new model for magnesium chemistry in the upper atmosphere.

    PubMed

    Plane, John M C; Whalley, Charlotte L

    2012-06-21

    This paper describes the kinetic study of a number of gas-phase reactions involving neutral Mg-containing species, which are important for the chemistry of meteor-ablated magnesium in the upper mesosphere/lower thermosphere region. The study is motivated by the very recent observation of the global atomic Mg layer around 90 km, using satellite-born UV-visible spectroscopy. In the laboratory, Mg atoms were produced thermally in the upstream section of a fast flow tube and then converted to the molecular species MgO, MgO(2), OMgO(2), and MgCO(3) by the addition of appropriate reagents. Atomic O was added further downstream, and Mg was detected at the downstream end of the flow tube by laser-induced fluorescence. The following rate coefficients were determined at 300 K: k(MgO + O → Mg + O(2)) = (6.2 ± 1.1) × 10(-10); k(MgO(2) + O → MgO + O(2)) = (8.4 ± 2.8) × 10(-11); k(MgCO(3) + O → MgO(2) + CO(2)) ≥ 4.9 × 10(-12); and k(MgO + CO → Mg + CO(2)) = (1.1 ± 0.3) × 10(-11) cm(3) molecule(-1) s(-1). Electronic structure calculations of the relevant potential energy surfaces combined with RRKM theory were performed to interpret the experimental results and also to explore the likely reaction pathways that convert MgCO(3) and OMgO(2) into long-lived reservoir species such as Mg(OH)(2). Although no reaction was observed in the laboratory between OMgO(2) and O, this is most likely due to the rapid recombination of O(2) with the product MgO(2) to form the relatively stable O(2)MgO(2). Indeed, one significant finding is the role of O(2) in the mesosphere, where it initiates holding cycles by recombining with radical species such as MgO(2) and MgOH. A new atmospheric model was then constructed which combines these results together with recent work on magnesium ion-molecule chemistry. The model is able to reproduce satisfactorily some of the key features of the Mg and Mg(+) layers, including the heights of the layers, the seasonal variations of their column

  17. Molecular identification of organic compounds in atmospheric complex mixtures and relationship to atmospheric chemistry and sources.

    PubMed Central

    Mazurek, Monica A

    2002-01-01

    This article describes a chemical characterization approach for complex organic compound mixtures associated with fine atmospheric particles of diameters less than 2.5 m (PM2.5). It relates molecular- and bulk-level chemical characteristics of the complex mixture to atmospheric chemistry and to emission sources. Overall, the analytical approach describes the organic complex mixtures in terms of a chemical mass balance (CMB). Here, the complex mixture is related to a bulk elemental measurement (total carbon) and is broken down systematically into functional groups and molecular compositions. The CMB and molecular-level information can be used to understand the sources of the atmospheric fine particles through conversion of chromatographic data and by incorporation into receptor-based CMB models. Once described and quantified within a mass balance framework, the chemical profiles for aerosol organic matter can be applied to existing air quality issues. Examples include understanding health effects of PM2.5 and defining and controlling key sources of anthropogenic fine particles. Overall, the organic aerosol compositional data provide chemical information needed for effective PM2.5 management. PMID:12634131

  18. Some Tests For Adaptative Observations In Atmospheric Chemistry

    NASA Astrophysics Data System (ADS)

    Quélo, D.; Michelangeli, P.-A.; Sportisse, B.

    Air pollution forecast requires the coupling of models with data through data assimi- lation. A key question is related to the choice of observations (apart from technical require- ments). One wants to choose in a judicious way the species to observe, in which loca- tions and at which moments. The appropriate strategies are related to the techniques of "targeting" and "adaptative observations". We will investigate these techniques on a simplified model. The first part reports the influence of the slow-fast behaviour of atmospheric chem- istry. The second part presents the use of singular vectors and second-order adjoint techniques in order to determine the "optimal" choice of observations. This project is led in the framework of the INRIA Cooperative Research Action CO- MODE (COupling MOdels and Data in Environment).

  19. Stereoscopic Projection in the Chemistry Classroom

    ERIC Educational Resources Information Center

    McGrew, LeRoy A.

    1972-01-01

    Describes the development of a three-dimensional projection system used to present structural principles by means of slides. Polarization of images from two planar projectors and viewing through polarized lenses gives stereo results. Techniques used in producing the slides and constructing the equipment are given. (TS)

  20. GEOLOGIC AND ATMOSPHERIC INPUT FACTORS AFFECTING WATERSHED CHEMISTRY IN UPPER MICHIGAN

    EPA Science Inventory

    The relationships between watershed variables and lakewater chemistry were examined for 53 lakes in the Upper Peninsula of Michigan to identify factors influencing lake sensitivity to atmospheric inputs. The lakes lie in three distinct geologic/geomorphic regions. Acid neutraliza...

  1. An Integrated Biology-Chemistry Freshman Laboratory Project in Biotechnology.

    ERIC Educational Resources Information Center

    Schendel, Marilyn Shimizu

    1999-01-01

    Describes a freshman biology laboratory project that uses the polymerase chain reaction to introduce students to the interrelationship between biology and chemistry. Students must develop their own experimental protocol, perform calculations introduced in freshman classes, and evaluate group dynamics. (Author/WRM)

  2. Chemistry-Materials Laboratory Project Book, 1979-80.

    ERIC Educational Resources Information Center

    Connecticut State Dept. of Education, Hartford. Bureau of Vocational-Technical Schools.

    This Chemistry-Materials Laboratory Project Book, assembled through a survey of science instructors in vocational-technical schools in Connecticut, is intended to meet a variety of needs. It can serve as an idea book, with the instructor taking from it as needed and adding or substituting material related to class interests; as a guide book for…

  3. Final-Year Education Projects for Undergraduate Chemistry Students

    ERIC Educational Resources Information Center

    Page, Elizabeth

    2011-01-01

    The Undergraduate Ambassadors Scheme provides an opportunity for students in their final year of the chemistry degree course at the University of Reading to choose an educational project as an alternative to practical research. The undergraduates work in schools where they can be regarded as role models and offer one way of inspiring pupils to…

  4. Simulating the impacts of large scale insect- and disease-driven tree mortality on atmospheric chemistry

    NASA Astrophysics Data System (ADS)

    Geddes, J.; Heald, C. L.; Silva, S. J.; Martin, R.

    2015-12-01

    Land-use and land-cover change (LUC) is an important driver of global change through the alteration of local energy, moisture, and carbon exchanges. LUC can also directly impact the emission and deposition of important reactive trace gases, altering the oxidative chemistry of the atmosphere and subsequently air quality and climate. Large-scale tree mortality as a result of insects and disease may therefore have unexplored feedbacks on atmospheric chemistry. Between 2013 and 2027, over 80 million acres of treed land in the United States is predicted to experience basal area mortality rates exceeding 25%. We harmonized the description of land cover across the relevant surface-atmosphere exchange processes in the GEOS-Chem chemical transport model to facilitate LUC simulations, and used this adapted model to test the impact of projected tree mortality according to the 2012 USDA National Insect and Disease Risk Assessment. Nation-wide biogenic VOC emissions were reduced by 5%, with local impacts approaching 50% in some regions. By themselves, these emission reductions resulted in lower surface-level O3 mixing ratios, but this was counteracted by decreases in the O3 deposition velocity (by up to 10%) due to the reduction in vegetation density. Organic aerosol mass concentrations were also significantly affected across the United States, decreasing by 5-10% across the eastern U.S. and the northwest, with local impacts exceeding 25% in some regions. We discuss the general impacts on air quality in clean and polluted regions of the US, and point to developments needed for a more robust understanding of land cover change feedbacks.

  5. he Impact of Primary Marine Aerosol on Atmospheric Chemistry, Radiation and Climate: A CCSM Model Development Study

    SciTech Connect

    Keene, William C.; Long, Michael S.

    2013-05-20

    This project examined the potential large-scale influence of marine aerosol cycling on atmospheric chemistry, physics and radiative transfer. Measurements indicate that the size-dependent generation of marine aerosols by wind waves at the ocean surface and the subsequent production and cycling of halogen-radicals are important but poorly constrained processes that influence climate regionally and globally. A reliable capacity to examine the role of marine aerosol in the global-scale atmospheric system requires that the important size-resolved chemical processes be treated explicitly. But the treatment of multiphase chemistry across the breadth of chemical scenarios encountered throughout the atmosphere is sensitive to the initial conditions and the precision of the solution method. This study examined this sensitivity, constrained it using high-resolution laboratory and field measurements, and deployed it in a coupled chemical-microphysical 3-D atmosphere model. First, laboratory measurements of fresh, unreacted marine aerosol were used to formulate a sea-state based marine aerosol source parameterization that captured the initial organic, inorganic, and physical conditions of the aerosol population. Second, a multiphase chemical mechanism, solved using the Max Planck Institute for Chemistry's MECCA (Module Efficiently Calculating the Chemistry of the Atmosphere) system, was benchmarked across a broad set of observed chemical and physical conditions in the marine atmosphere. Using these results, the mechanism was systematically reduced to maximize computational speed. Finally, the mechanism was coupled to the 3-mode modal aerosol version of the NCAR Community Atmosphere Model (CAM v3.6.33). Decadal-scale simulations with CAM v.3.6.33, were run both with and without reactive-halogen chemistry and with and without explicit treatment of particulate organic carbon in the marine aerosol source function. Simulated results were interpreted (1) to evaluate influences of

  6. Alternative Solvents through Green Chemistry Project

    NASA Technical Reports Server (NTRS)

    Hintze, Paul E.; Quinn, Jacqueline

    2014-01-01

    Components in the aerospace industry must perform with accuracy and precision under extreme conditions, and surface contamination can be detrimental to the desired performance, especially in cases when the components come into contact with strong oxidizers such as liquid oxygen. Therefore, precision cleaning is an important part of a components preparation prior to utilization in aerospace applications. Current cleaning technologies employ a variety of cleaning agents, many of which are halogenated solvents that are either toxic or cause environmental damage. Thus, this project seeks to identify alternative precision cleaning solvents and technologies, including use of less harmful cleaning solvents, ultrasonic and megasonic agitation, low-pressure plasma cleaning techniques, and supercritical carbon dioxide extraction. Please review all data content found in the Public Data tab located at: https:techport.nasa.govview11697public

  7. NASA's Upper Atmosphere Research Program UARP and Atmospheric Chemistry Modeling and Analysis Program (ACMAP): Research Summaries 1994 - 1996. Report to Congress and the Environmental Protection Agency

    NASA Technical Reports Server (NTRS)

    Kendall, Rose (Compiler); Wolfe, Kathy (Compiler)

    1997-01-01

    Under the mandate contained in the FY 1976 NASA Authorization Act, the National Aeronautics and Space Administration (NASA) has developed and is implementing a comprehensive program of research, technology, and monitoring of the Earth's upper atmosphere, with emphasis on the stratosphere. This program aims at expanding our understanding to permit both the quantitative analysis of current perturbations as well as the assessment of possible future changes in this important region of our environment. It is carried out jointly by the Upper Atmosphere Research Program (UARP) and the Atmospheric Chemistry Modeling and Analysis Program (ACMAP), both managed within the Science Division in the Office of Mission to Planet Earth at NASA. Significant contributions to this effort are also provided by the Atmospheric Effects of Aviation Project (AEAP) of NASA's Office of Aeronautics. The long-term objectives of the present program are to perform research to: understand the physics, chemistry, and transport processes of the upper atmosphere and their effect on the distribution of chemical species in the stratosphere, such as ozone; understand the relationship of the trace constituent composition of the lower stratosphere and the lower troposphere to the radiative balance and temperature distribution of the Earth's atmosphere; and accurately assess possible perturbations of the upper atmosphere caused by human activities as well as by natural phenomena. In compliance with the Clean Air Act Amendments of 1990, Public Law 101-549, NASA has prepared a report on the state of our knowledge of the Earth's upper atmosphere, particularly the stratosphere, and on the progress of UARP and ACMAP. The report for the year 1996 is composed of two parts. Part 1 summarizes the objectives, status, and accomplishments of the research tasks supported under NASA UARP and ACMAP in a document entitled, Research Summary 1994-1996. Part 2 is entitled Present State of Knowledge of the Upper Atmosphere

  8. CHEMISTRY OF SILICATE ATMOSPHERES OF EVAPORATING SUPER-EARTHS

    SciTech Connect

    Schaefer, Laura; Fegley, Bruce E-mail: bfegley@levee.wustl.ed

    2009-10-01

    We model the formation of silicate atmospheres on hot volatile-free super-Earths. Our calculations assume that all volatile elements such as H, C, N, S, and Cl have been lost from the planet. We find that the atmospheres are composed primarily of Na, O{sub 2}, O, and SiO gas, in order of decreasing abundance. The atmospheric composition may be altered by fractional vaporization, cloud condensation, photoionization, and reaction with any residual volatile elements remaining in the atmosphere. Cloud condensation reduces the abundance of all elements in the atmosphere except Na and K. We speculate that large Na and K clouds such as those observed around Mercury and Io may surround hot super-Earths. These clouds would occult much larger fractions of the parent star than a closely bound atmosphere, and may be observable through currently available methods.

  9. Advanced Placement Chemistry: Project Advance and the Advanced Placement Program: A Comparison of Students' Performance on the AP Chemistry Examination.

    ERIC Educational Resources Information Center

    Mercurio, Joseph; And Others

    1984-01-01

    Compared performance of Syracuse University Project Advance (PA) chemistry students (N=35) with advanced placement (AP) candidates on the AP chemistry examination. PA students scored slightly above the national average on the examination, and students who performed well (B or better) in AP chemistry also did well on the examination. (JN)

  10. Atmospheric chemistry and environmental impact of the use of amines in carbon capture and storage (CCS).

    PubMed

    Nielsen, Claus J; Herrmann, Hartmut; Weller, Christian

    2012-10-01

    This critical review addresses the atmospheric gas phase and aqueous phase amine chemistry that is relevant to potential emissions from amine-based carbon capture and storage (CCS). The focus is on amine, nitrosamine and nitramine degradation, and nitrosamine and nitramine formation processes. A comparison between the relative importance of the various atmospheric sinks for amines, nitrosamines and nitramines is presented. PMID:22729147

  11. Nucla circulating atmospheric fluidized bed demonstration project

    SciTech Connect

    Keith, Raymond E.

    1991-10-01

    Colorado-Ute Electric Association began a study to evaluate options for upgrading and extending the life of its Nucla power station in 1982. Located in southwestern Colorado near the town of Nucla, this station was commissioned in 1959 with a local bituminous coal as its design fuel for three identical stoker-fired units, each rated at 12.6 MW(e). Poor station efficiency, high fuel costs, and spiraling boiler maintenance costs forced the Nucla Station into low priority in the CUEA dispatch order as early as 1981. Among the options CUEA considered was to serve as a host utility to demonstrate Atmospheric Fluidized Bed Combustion (AFBC) technology. The anticipated environmental benefits and apparent attractive economics of a circulating AFBC led to Colorado-Ute's decision to proceed with the design and construction of a demonstration project in 1984 at the Nucla facility.

  12. NASA's Atmospheric Effects of Aviation Project

    NASA Technical Reports Server (NTRS)

    Cofer, W. Randy, III; Anderson, Bruce E.; Connors, V. S.; Wey, C. C.; Sanders, T.; Winstead, E. L.; Pui, C.; Chen, Da-ren; Hagen, D. E.; Whitefield, P.

    2001-01-01

    During August 1-14, 1999, NASA's Atmospheric Effects of Aviation Project (AEAP) convened a workshop at the NASA Langley Research Center to try to determine why such a wide variation in aerosol emissions indices and chemical and physical properties has been reported by various independent AEAP-supported research teams trying to characterize the exhaust emissions of subsonic commercial aircraft. This workshop was divided into two phases, a laboratory phase and a field phase. The laboratory phase consisted of supplying known particle number densities (concentrations) and particle size distributions to a common manifold for the participating research teams to sample and analyze. The field phase was conducted on an aircraft run-up pad. Participating teams actually sampled aircraft exhaust generated by a Langley T-38 Talon aircraft at 1 and 9 m behind the engine at engine powers ranging from 48 to 100 percent. Results from the laboratory phase of this intercomparison workshop are reported in this paper.

  13. Atmospheric model intercomparison project: Monsoon simulations

    SciTech Connect

    Sperber, K.R.; Palmer, T.N.

    1994-06-01

    The simulation of monsoons, in particular the Indian summer monsoon, has proven to be a critical test of a general circulation model`s ability to simulate tropical climate and variability. The Monsoon Numerical Experimentation Group has begun to address questions regarding the predictability of monsoon extremes, in particular conditions associated with El Nino and La Nina conditions that tend to be associated with drought and flood conditions over the Indian subcontinent, through a series of seasonal integrations using analyzed initial conditions from successive days in 1987 and 1988. In this paper the authors present an analysis of simulations associated with the Atmospheric Model Intercomparison Project (AMIP), a coordinated effort to simulate the 1979--1988 decade using standardized boundary conditions with approximately 30 atmospheric general circulation models. The 13 models analyzed to date are listed. Using monthly mean data from these simulations they have calculated indices of precipitation and wind shear in an effort to access the performance of the models over the course of the AMIP decade.

  14. Investigating Titan's Atmospheric Chemistry at Low Temperature in Support of the NASA Cassini Mission

    NASA Technical Reports Server (NTRS)

    Sciamma-O'Brien, Ella; Salama, Farid

    2013-01-01

    Titan's atmosphere, composed mainly of N2 and CH4, is the siege of a complex chemistry induced by solar UV radiation and electron bombardment from Saturn's magnetosphere. This organic chemistry occurs at temperatures lower than 200 K and leads to the production of heavy molecules and subsequently solid aerosols that form the orange haze surrounding Titan. The Titan Haze Simulation (THS) experiment has been developed on the COSMIC simulation chamber at NASA Ames in order to study the different steps of Titan's atmospheric chemistry at low temperature and to provide laboratory data in support for Cassini data analysis. The chemistry is simulated by plasma in the stream of a supersonic expansion. With this unique design, the gas mixture is adiabatically cooled to Titan-like temperature (approx. 150 K) before inducing the chemistry by plasma discharge. Different gas mixtures containing N2, CH4, and the first products of the N2,-CH4 chemistry (C2H2, C2H4, C6H6...) but also heavier molecules such as PAHs or nitrogen containing PAHs can be injected. Both the gas phase and solid phase products resulting from the plasma-induced chemistry can be monitored and analyzed. Here we present the results of recent gas phase and solid phase studies that highlight the chemical growth evolution when injecting heavier hydrocarbon trace elements in the initial N2-CH4 mixture. Due to the short residence time of the gas in the plasma discharge, only the first steps of the chemistry have time to occur in a N2-CH4 discharge. However by adding acetylene and benzene to the initial N2-CH4 mixture, we can study the intermediate steps of Titan's atmospheric chemistry as well as specific chemical pathways. These results show the uniqueness of the THS experiment to help understand the first and intermediate steps of Titan fs atmospheric chemistry as well as specific chemical pathways leading to Titan fs haze formation.

  15. On the physics, chemistry and toxicology of ultrafine anthropogenic, atmospheric aerosols (UAAA): new advances.

    PubMed

    Spurny, K R

    1998-08-01

    The existing data about the epidemiology, toxicology, physics and chemistry of atmospheric particulate pollutants were recently essentially completed and extended. They do support the hypothesis that the fine and very fine dispersed fraction of the atmospheric anthropogenic aerosols (UAAA) are responsible for the aggravation of the health risk potential of the polluted atmosphere during the last decade. The recently published data dealing primarily with the physics, chemistry, sampling and analysis of these highly dispersed particulate air pollutants are reviewed, summarized and critically evaluated. PMID:9820675

  16. A lookup table to compute high energy cosmic ray effects on terrestrial atmospheric chemistry

    NASA Astrophysics Data System (ADS)

    Atri, Dimitra

    A variety of events such as gamma-ray bursts and supernovae may expose the Earth to an increased flux of high-energy cosmic rays, with potentially important effects on the biosphere. Existing atmospheric chemistry software does not have the capability of incorporating the effects of substantial cosmic ray flux above 10 GeV . An atmospheric code, the NASA-Goddard Space Flight Center two-dimensional (latitude, altitude) time-dependent atmospheric model (NGSFC), is used to study atmospheric chemistry changes. We have created a table that, with the use of the NGSFC code, can be used to simulate the effects of high energy cosmic rays (10 GeV - 1 PeV ) ionizing the atmosphere. By interpolation, the table can be used to generate values for other uses which depend upon atmospheric energy deposition by ensembles of high-energy cosmic rays. We discuss the table, its use, weaknesses, and strengths.

  17. Remote sensing of atmospheric chemistry; Proceedings of the Meeting, Orlando, FL, Apr. 1-3, 1991

    NASA Technical Reports Server (NTRS)

    Mcelroy, James L. (Editor); Mcneal, Robert J. (Editor)

    1991-01-01

    The present volume on remote sensing of atmospheric chemistry discusses special remote sensing space observations and field experiments to study chemical change in the atmosphere, network monitoring for detection of stratospheric chemical change, stratospheric chemistry studies, and the combining of model, in situ, and remote sensing in atmospheric chemistry. Attention is given to the measurement of tropospheric carbon monoxide using gas filter radiometers, long-path differential absorption measurements of tropospheric molecules, air quality monitoring with the differential optical absorption spectrometer, and a characterization of tropospheric methane through space-based remote sensing. Topics addressed include microwave limb sounder experiments for UARS and EOS, an overview of the spectroscopy of the atmosphere using an FIR emission experiment, the detection of stratospheric ozone trends by ground-based microwave observations, and a FIR Fabry-Perot spectrometer for OH measurements.

  18. Experimental and Theoretical Studies of Atmosphereic Inorganic Chlorine Chemistry

    NASA Technical Reports Server (NTRS)

    Sander, Stanley P.; Friedl, Randall R.

    1993-01-01

    Over the last five years substantial progress has been made in defining the realm of new chlorine chemistry in the polar stratosphere. Application of existing experimental techniques to potentially important chlorine-containing compounds has yielded quantitative kinetic and spectroscopic data as well as qualitative mechanistic insights into the relevant reactions.

  19. Atmospheric OCS measurements on Project Gametag

    NASA Astrophysics Data System (ADS)

    Torres, A. L.; Maroulis, P. J.; Goldberg, A. B.; Bandy, A. R.

    1980-12-01

    In the spring of 1978, carbonyl sulfide measurements were made at Drexel University in Philadelphia, Pennsylvania, and on Project Gametag (Global Atmospheric Measurements Experiment of Tropospheric Aerosols and Gases). At Drexel University, measurements were made on 7 days in mid-March, using a dual-channel sampling system. These data had a mean concentration and standard deviation of 544±27 pptv on channel 1 and 522±27 pptv on channel 2. In project Gametag, 346 measurements of the tropospheric concentration of OCS were made over a latitude range 57°S to 70°N. Samples were obtained over the central and southern Pacific Ocean and the western sections of the United States and Canada. Overall OCS levels averaged 512 pptv with a standard deviation of 65 pptv and a standard error of the mean of 4 pptv. Carbonyl sulfide levels were statistically the same in the free troposphere and the boundary layer and over continental and marine areas. The apparent north-south gradient seen in the Gametag data set was attributed to a change in the calibration system as a function of time during the experiment.

  20. 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.

  1. Atmospheric Chemistry from Space: Present Status and Future Plans

    NASA Technical Reports Server (NTRS)

    Schoeberl, Mark R.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    One of the unqualified successes of the earth observation program is NASA's continuing monitoring of the ozone layer from space. This activity began in the early 70's with research instruments and continues to this day with the TOMS instrument series and the Upper Atmosphere Research Satellite. In the near future, NASA will be launching the EOS Aura spacecraft (launch mid-2003) which will continue our study of the chemical processes that produce stratospheric ozone depletion. In addition, Aura will begin the first global study of lower atmospheric air pollution including urban ozone, aerosols, nitrogen oxides and carbon monoxide. Atmospheric air pollution measurements from earth orbit involve the development of very high precision spectrometer technologies that have never been flown in space. Farther into the future, lower atmospheric ozone and aerosols may be monitored by space based lidars in low earth orbit, by sensors in geostationary orbit and by continuous limb observations instrument from the Lagrange point L2.

  2. Project-based learning in the secondary chemistry classroom

    NASA Astrophysics Data System (ADS)

    Crane, Elizabeth L.

    This study investigated the use of project-based learning (PBL) in a high school chemistry classroom. PBL encourages the use of projects, which promote continual learning, rather than a summative project at the end of a unit after the learning has already been done. Along with implementing PBL, the study also incorporated many of the strategies included in the broader strategy known as Assessment for Learning (AfL), which stresses developing assessments that are part of the learning process rather than simply a measurement of the amount of learning that has occurred upon completion of a unit. The hypothesis of this research was that PBL would increase student comprehension and motivation as measured through pre and post-test data and a student survey. The new project-based unit required students to research and present the properties and structures of elements and how we use them. The expectation was that this approach would engage students with the material, the computer modeling would allow for more concrete visualization of structures and the project-based format would allow students to become more invested in their own learning. This study provided evidence to support the hypothesis that the implementation of project-based learning, supported by formative assessment and other assessment for learning strategies, will improve student comprehension and motivation in the secondary chemistry classroom.

  3. The Skylab concentrated atmospheric radiation project

    NASA Technical Reports Server (NTRS)

    Kuhn, P. M.; Marlatt, W. E.; Whitehead, V. S. (Principal Investigator)

    1975-01-01

    The author has identified the following significant results. Comparison of several existing infrared radiative transfer models under somewhat controlled conditions and with atmospheric observations of Skylab's S191 and S192 radiometers illustrated that the models tend to over-compute atmospheric attenuation in the window region of the atmospheric infrared spectra.

  4. Chemistry of atmosphere-surface interactions on Venus and Mars

    NASA Technical Reports Server (NTRS)

    Fegley, Bruce, Jr.; Treiman, Allan H.

    1992-01-01

    Earth-based, earth-orbital, and spacecraft observational data are used in the present evaluation of Venus atmosphere-surface interactions to quantitatively characterize the reactions between C, H, S, Cl, F, and N gases and plausible surface minerals. Calculation results are used to predict stable minerals and mineral assemblages on the Venus surface, in order to ascertain which (if any) of the atmospheric gases are buffeted by mineral assemblages. Chemical equilibrium calculations using extant thermodynamic data on scapolite minerals predict that carbonate-bearing scapolite and sulfate meionite are unstable on the surface of Venus, while chloride-bearing scapolite is stable.

  5. Size resolved fog water chemistry and its atmospheric implications

    NASA Astrophysics Data System (ADS)

    Chakraborty, Abhishek; Gupta, Tarun; Tripathi, Sachchida; Ervens, Barbara; Bhattu, Deepika

    2015-04-01

    Fog is a natural meteorological phenomenon that occurs throughout the world. It usually contains substantial quantity of liquid water and results in severe visibility reduction leading to disruption of normal life. Fog is generally seen as a natural cleansing agent but it also has the potential to form Secondary Organic Aerosol (SOA) via aqueous processing of ambient aerosols. Size- resolved fog water chemistry for inorganics were reported in previous studies but processing of organics inside the fog water and quantification of aqSOA remained a challenge. To assess the organics processing via fog aqueous processing, size resolved fog water samples were collected in two consecutive winter seasons (2012-13, 2013-14) at Kanpur, a heavily polluted urban area of India. Caltech 3 stage fog collector was used to collect the fog droplets in 3 size fraction; coarse (droplet diameter > 22 µm), medium (22> droplet diameter >16 µm) and fine (16> droplet diameter >4 µm). Collected samples were atomized into various instruments such as Aerosol Mass Spectrometer (AMS), Cloud Condensation Nucleus Counter (CCNc), Total Organic Carbon (TOC) and a thermo denuder (TD) for the physico-chemical characterization of soluble constituents. Fine droplets are found to be more enriched with different aerosol species and interestingly contain more aged and less volatile organics compared to other coarser sizes. Organics inside fine droplets have an average O/C = 0.87 compared to O/C of 0.67 and 0.74 of coarse and medium droplets. Metal chemistry and higher residence time of fine droplets are seemed to be the two most likely reasons for this outcome from as the results of a comprehensive modeling carried out on the observed data indicate. CCN activities of the aerosols from fine droplets are also much higher than that of coarse or medium droplets. Fine droplets also contain light absorbing material as was obvious from their 'yellowish' solution. Source apportionment of fog water organics via

  6. Seasonal variations in atmospheric chemistry in the Adirondacks

    SciTech Connect

    Kelly, T.J.; Tanner, R.L.; McLaren, S.E.; DuBois, M.V.

    1985-03-01

    The results of continuous real-time measurements of aerosol composition, HNO/sub 3/, and SO/sub 2/, performed at the summit of Whiteface Mountain, New York, during 1984 are reported. The purpose was to shed light on the seasonal variation in atmospheric acidity in this ecologically sensitive area. 13 refs., 5 figs. (ACR)

  7. Inorganic chemistry of O2 in a dense primitive atmosphere

    PubMed

    Rosenqvist, J; Chassefière, E

    1995-01-01

    A simple steady-state photochemical model is developed in order to determine typical molecular oxygen concentrations for a comprehensive range of primitive abiotic atmospheres. Carbon dioxide is assumed to be the dominant constituent in these atmospheres since CO2 photodissociation may potentially result in the enhancement of the O2 partial pressure. The respective effects of the H2O content, temperature, eddy diffusion coefficient and UV flux on the results are investigated. It is shown that for any pressure at the surface, the partial pressure of molecular oxygen does not exceed 10 mbar. The peculiar case of a runaway greenhouse which has possibly taken place on Venus is qualitatively envisaged. Although O2 is basically absent in the present Venus atmosphere, a transient presence in a primitive stage cannot be ruled out. Possible mechanisms for O2 removal in such an atmosphere are reviewed. At the present stage, we think that the detection of large O2 amounts would be at least a good clue for the presence of life on an extrasolar planet. PMID:11538435

  8. Electrostatic activation of prebiotic chemistry in substellar atmospheres

    NASA Astrophysics Data System (ADS)

    Stark, C. R.; Helling, Ch.; Diver, D. A.; Rimmer, P. B.

    2014-04-01

    Charged dust grains in the atmospheres of exoplanets may play a key role in the formation of prebiotic molecules, necessary to the origin of life. Dust grains submerged in an atmospheric plasma become negatively charged and attract a flux of ions that are accelerated from the plasma. The energy of the ions upon reaching the grain surface may be sufficient to overcome the activation energy of particular chemical reactions that would be unattainable via ion and neutral bombardment from classical, thermal excitation. As a result, prebiotic molecules or their precursors could be synthesized on the surface of dust grains that form clouds in exoplanetary atmospheres. This paper investigates the energization of the plasma ions, and the dependence on the plasma electron temperature, in the atmospheres of substellar objects such as gas giant planets. Calculations show that modest electron temperatures of ~1 eV (~104 K) are enough to accelerate ions to sufficient energies that exceed the activation energies required for the formation of formaldehyde, ammonia, hydrogen cyanide and the amino acid glycine.

  9. Advances in atmospheric chemistry modeling: the LLNL impact tropospheric/stratospheric chemistry model

    SciTech Connect

    Rotman, D A; Atherton, C

    1999-10-07

    We present a unique modeling capability to understand the global distribution of trace gases and aerosols throughout both the troposphere and stratosphere. It includes the ability to simulate tropospheric chemistry that occurs both in the gas phase as well as on the surfaces of solid particles. We have used this capability to analyze observations from particular flight campaigns as well as averaged observed data. Results show the model to accurately simulate the complex chemistry occurring near the tropopause and throughout the troposphere and stratosphere.

  10. Potential changes in atmospheric chemistry in the decades ahead: Climate and biosphere interactions and feedbacks

    SciTech Connect

    Gaffney, J.S.; Marley, N.A.

    1991-10-01

    Atmospheric chemistry is a challenging area of research where much knowledge is needed if we are to continue to survive as a species. This paper outlines research needs in the decades ahead in this key area of scientific endeavor. Highlighted are areas of research that are likely to lead to climatic and biospheric impacts and have been given little attention in the past. In particular, the possible organic transformation chemistries that may lead to chemical and physical changes in tropospheric cloud chemistries are highlighted and emphasized as an area where research is needed in the future. 22 refs.

  11. Non-Equilibrium Thermodynamic Chemistry and the Composition of the Atmosphere of Mars

    NASA Technical Reports Server (NTRS)

    Levine, J. S.; Summers, M. E.

    2003-01-01

    A high priority objective of the Mars Exploration Program is to Determine if life exists today (MEPAG Goal I, Objective A). The measurement of gases of biogenic origin may be an approach to detect the presence of microbial life on the surface or subsurface of Mars. Chemical thermodynamic calculations indicate that on both Earth and Mars, certain gases should exist in extremely low concentrations, if at all. Microbial metabolic activity is an important non-equilibrium chemistry process on Earth, and if microbial life exists on Mars, may be an important nonequilibrium chemistry process on Mars. The non-equilibrium chemistry of the atmosphere of Mars is discussed in this paper.

  12. Strong atmospheric chemistry feedback to climate warming from Arctic methane emissions

    USGS Publications Warehouse

    Isaksen, Ivar S.A.; Gauss, Michael; Myhre, Gunnar; Walter Anthony, Katey M.; Ruppel, Carolyn

    2011-01-01

    The magnitude and feedbacks of future methane release from the Arctic region are unknown. Despite limited documentation of potential future releases associated with thawing permafrost and degassing methane hydrates, the large potential for future methane releases calls for improved understanding of the interaction of a changing climate with processes in the Arctic and chemical feedbacks in the atmosphere. Here we apply a “state of the art” atmospheric chemistry transport model to show that large emissions of CH4 would likely have an unexpectedly large impact on the chemical composition of the atmosphere and on radiative forcing (RF). The indirect contribution to RF of additional methane emission is particularly important. It is shown that if global methane emissions were to increase by factors of 2.5 and 5.2 above current emissions, the indirect contributions to RF would be about 250% and 400%, respectively, of the RF that can be attributed to directly emitted methane alone. Assuming several hypothetical scenarios of CH4 release associated with permafrost thaw, shallow marine hydrate degassing, and submarine landslides, we find a strong positive feedback on RF through atmospheric chemistry. In particular, the impact of CH4 is enhanced through increase of its lifetime, and of atmospheric abundances of ozone, stratospheric water vapor, and CO2 as a result of atmospheric chemical processes. Despite uncertainties in emission scenarios, our results provide a better understanding of the feedbacks in the atmospheric chemistry that would amplify climate warming.

  13. The role of computational chemistry in the science and measurements of the atmosphere

    NASA Technical Reports Server (NTRS)

    Phillips, D. H.

    1978-01-01

    The role of computational chemistry in determining the stability, photochemistry, spectroscopic parameters, and parameters for estimating reaction rates of atmospheric constituents is discussed. Examples dealing with the photolysis cross sections of HOCl and (1 Delta g) O2 and with the stability of gaseous NH4Cl and asymmetric ClO3 are presented. It is concluded that computational chemistry can play an important role in the study of atmospheric constituents, particularly reactive and short-lived species which are difficult to investigate experimentally.

  14. Atmospheric chemistry of hydrogen halides: Reactions on ice and in strong acids

    SciTech Connect

    Ravishankara, A.R.

    1995-12-31

    Reactions of hydrogen halides, HCl, HBr, and HI, in sulfuric acid droplets, ice, and liquid water play important roles in the chemistry of Earth`s atmosphere. The hydrogen halides react with other species such as HOCl, ClONO{sub 2}, BrONO{sub 2}, and HOBr to liberate active halogens, the form that can destroy ozone. The impact of these reactions on the chemistry of the ozone in the atmosphere will be described. Also, a brief discussion of the mechanisms of these reactions will be given. Possible experimental and theoretical investigations that can shed light on these reactions will be pointed out.

  15. Investigations of Global Chemistry-Climate Interactions and Organic Aerosol Using Atmospheric Modeling

    NASA Astrophysics Data System (ADS)

    Pye, Havala Olson Taylor

    Aerosol, or particulate matter (PM), is an important component of the atmosphere responsible for negative health impacts, environmental degradation, reductions in visibility, and climate change. In this work, the global chemical transport model, GEOS-Chem, is used as a tool to examine chemistry-climate interactions and organic aerosols. GEOS-Chem is used to simulate present-day (year 2000) and future (year 2050) sulfate, nitrate, and ammonium aerosols and investigate the potential effects of changes in climate and emissions on global budgets and U.S. air quality. Changes in a number of meteorological parameters, such as temperature and precipitation, are potentially important for aerosols and could lead to increases or decreases in PM concentrations. Although projected changes in sulfate and nitrate precursor emissions favor lower PM concentrations over the U.S., projected increases in ammonia emissions could result in higher nitrate concentrations. The organic aerosol simulation in GEOS-Chem is updated to include aerosol from primary semivolatile organic compounds (SVOCS), intermediate volatility compounds (IVOCs), NOx dependent terpene aerosol, and aerosol from isoprene + NO3 reaction. SVOCs are identified as the largest global source of organic aerosol even though their atmospheric transformation is highly uncertain and emissions are probably underestimated. As a result of significant nighttime terpene emissions, fast reaction of monoterpenes with the nitrate radical, and high aerosol yields from NO3 oxidation, biogenic hydrocarbons reacting with the nitrate radical are expected to be a major contributor to surface level aerosol concentrations in anthropogenically influenced areas such as the United States. Globally, 69 to 88 Tg/yr of aerosol is predicted to be produced annually, approximately 22 to 24 Tg/yr of which is from biogenic hydrocarbons.

  16. Martian atmospheric chemistry during the time of low water abundance

    NASA Technical Reports Server (NTRS)

    Nair, Hari; Allen, Mark; Yung, Yuk L.; Clancy, R. Todd

    1992-01-01

    The importance of odd hydrogen (or HO(x)) radicals in the catalytic recombination of carbon monoxide and oxygen in the Martian atmosphere is a well known fact. The inclusion of recent chemical kinetics data, specifically temperature-dependent CO2 absorption cross sections, into our one dimensional photochemical model shows that HO(x) is too efficient in this regard. The absorption cross sections of CO2 are smaller than previously assumed; this leads to a reduction in the photolysis rate of CO2 while the photolysis rate of H2O has increased. As a consequence the predicted mixing ratio of CO in our models is substantially less than the observed value of 6.5(10)(exp -4). Simultaneous measurements of water, ozone, and carbon monoxide were obtained in the Martian atmosphere in early Dec. 1990 (L(sub s) for Mars was 344 deg.).

  17. Atmospheric oxidation chemistry and ozone production: Results from SHARP 2009 in Houston, Texas

    NASA Astrophysics Data System (ADS)

    Ren, Xinrong; Duin, Diana; Cazorla, Maria; Chen, Shuang; Mao, Jingqiu; Zhang, Li; Brune, William H.; Flynn, James H.; Grossberg, Nicole; Lefer, Barry L.; Rappenglück, Bernhard; Wong, Kam W.; Tsai, Catalina; Stutz, Jochen; Dibb, Jack E.; Thomas Jobson, B.; Luke, Winston T.; Kelley, Paul

    2013-06-01

    Ozone (O3) and secondary fine particles come from the atmospheric oxidation chemistry that involves the hydroxyl radical (OH) and hydroperoxyl radical (HO2), which are together called HOx. Radical precursors such as nitrous acid (HONO) and formaldehyde (HCHO) significantly affect the HOx budget in urban environments. These chemical processes connect surface anthropogenic and natural emissions to local and regional air pollution. Using the data collected during the Study of Houston Atmospheric Radical Precursors (SHARP) in spring 2009, we examine atmospheric oxidation chemistry and O3 production in this polluted urban environment. A numerical box model with five different chemical mechanisms was used to simulate the oxidation processes and thus OH and HO2 in this study. In general, the model reproduced the measured OH and HO2 with all five chemical mechanisms producing similar levels of OH and HO2, although midday OH was overpredicted and nighttime OH and HO2 were underpredicted. The calculated HOx production was dominated by HONO photolysis in the early morning and by the photolysis of O3 and oxygenated volatile organic compounds (OVOCs) in the midday. On average, the daily HOx production rate was 24.6 ppbv d-1, of which 30% was from O3 photolysis, 22% from HONO photolysis, 15% from the photolysis of OVOCs (other than HCHO), 14% from HCHO photolysis, and 13% from O3 reactions with alkenes. The O3 production was sensitive to volatile organic compounds (VOCs) in the early morning but was sensitive to NOx for most of afternoon. This is similar to the behavior observed in two previous summertime studies in Houston: the Texas Air Quality Study in 2000 (TexAQS 2000) and the TexAQS II Radical and Aerosol Measurement Project in 2006 (TRAMP 2006). Ozone production in SHARP exhibits a longer NOx-sensitive period than TexAQS 2000 and TRAMP 2006, indicating that NOx control may be an efficient approach for the O3 control in springtime for Houston. Results from this study

  18. Precipitation chemistry - Atmospheric loadings to the surface waters of the Indian River lagoon basin by rainfall

    NASA Technical Reports Server (NTRS)

    Dreschel, Thomas W.; Madsen, Brooks C.; Maull, Lee A.; Hinkle, C. R.; Knott, William M., III

    1990-01-01

    Rain volume and chemistry monitoring as part of the Kennedy Space Center Long Term Environmental Monitoring Program included the years 1984-1987 as part of the National Atmospheric Deposition Program. Atmospheric deposition in rainfall consisted primarily of sea salt and hydrogen ion, sulfate, nitrate, and ammonium ions. The deposition of nitrogen (a principal plant nutrient) was on the order of 200-300 metric tons per year to the surface waters.

  19. The Exchange of Soil Nitrite and Atmospheric HONO: a Missing Process in the Nitrogen Cycle and Atmospheric Chemistry

    NASA Astrophysics Data System (ADS)

    Cheng, Yafang; Su, Hang; Oswald, Robert; Behrendt, Thomas; Trebs, Ivonne; Meixner, Franz X.; Andreae, Meinrat O.; Pöschl, Ulrich

    2013-04-01

    Hydroxyl radicals (OH) are a key species in atmospheric photochemistry. In the lower atmosphere, up to ~30% of the primary OH radical production is attributed to the photolysis of nitrous acid (HONO), and field observations suggest a large missing source of HONO. The dominant sources of N(III) in soil, however, are biological nitrification and denitrification processes, which produce nitrite ions from ammonium (by nitrifying microbes) as well as from nitrate (by denitrifying microbes). We show that soil nitrite can release HONO and explain the reported strength and diurnal variation of the missing source. We also show that the soil-atmosphere exchange of N(III), though not considered in the N cycle, might result in significant amount of reactive nitrogen emission (comparable to soil NO emissions). Fertilized soils with low pH appear to be particularly strong sources of HONO and OH. Thus, agricultural activities and land-use changes may strongly influence the oxidizing capacity of the atmosphere. Because of the widespread occurrence of nitrite-producing microbes and increasing N and acid deposition, the release of HONO from soil may also be important in natural environments, including forests and boreal regions. In view of the potentially large impact on atmospheric chemistry and global environmental change, we recommend further studies of HONO release from soil nitrite and related processes in the biogeochemical cycling of N in both agricultural and natural environments. Reference: Su, H., Cheng, Y., et al., Soil Nitrite as a Source of Atmospheric HONO and OH Radicals, Science, 333, 1616-1618, 10.1126/science.1207687, 2011. Su, H., et al., The Exchange of Soil Nitrite and Atmospheric HONO: A Missing Process in the Nitrogen Cycle and Atmospheric Chemistry, NATO Science for Peace and Security Series C: Environmental Security, Springer Netherlands, 93-99, 2013.

  20. Optical methods in atmospheric chemistry; Proceedings of the Meeting, Berlin, Germany, June 22-24, 1992

    NASA Astrophysics Data System (ADS)

    Schiff, Harold I.; Platt, Ulrich

    Various papers on atmospheric chemistry are presented. Individual topics addressed include: molecular modulation spectroscopy studies involving peroxy radical reactions, spectroscopic studies of model polar stratospheric cloud films, rates of hydroxyl radical reactions with some HFCs, heterogeneous processes of nitrogen dioxide on liquid surfaces, temperature-dependence absorption cross sections for HNO3 and H2O5, tunable-diode-laser-based monitoring of atmospheric gases, compact tunable diode laser spectrometer for environmental monitoring, improved open-path multireflection cell for the measurement of NO2 and NO3, problems in global atmospheric chemistry, scattered sky observations of stratospheric OClO at McMurdo Station, star-pointing UV-visible spectrometer for remote sensing of the stratosphere. Also discussed are: sensitivity limits of laser intracavity spectroscopy, novel ranging UV-visible spectrometer for remote sensing of the troposphere, balloon-borne measurements of the actinic flux in the UV spectral region, balloon-borne submillimeter-wave stratospheric measurements, FIR Fabry-Perot spectrometer for OH measurements, ESA's contribution to atmospheric chemistry, the ATLAS-1 mission atmospheric trace molecular spectroscopy experiment, thermal sounding of the atmosphere under non-LTE conditions, GOME instrument simulation, global ozone monitoring experiment on board ERS 2.

  1. Atmospheric chemistry of CF3CF2OCH3

    NASA Astrophysics Data System (ADS)

    Østerstrøm, Freja F.; Nielsen, Ole John; Wallington, Timothy J.

    2016-06-01

    Smog chamber Fourier transform infrared techniques were used to investigate the kinetics of the reaction of CF3CF2OCH3 with Cl atoms and OH radicals: k(Cl + CF3CF2OCH3) = (1.09 ± 0.16) × 10-13 and k(OH + CF3CF2OCH3) = (1.28 ± 0.19) × 10-14 cm3 molecule-1 s-1 in 700 Torr total pressure of N2/O2 at 296 ± 2 K. The Cl-initiated oxidation of CF3CF2OCH3 gives CF3CF2OCHO in a yield indistinguishable from 100%. An estimate of k(Cl + CF3CF2OCHO) = (1.18 ± 0.34) × 10-14 cm3 molecule-1 s-1 is provided. Based on the OH reaction rate, the atmospheric lifetime of CF3CF2OCH3 is estimated to be 5.0 years. The 100-year time horizon global warming potential of CF3CF2OCH3 is estimated to be 585. The atmospheric impact of CF3CF2OCH3 is discussed.

  2. On the numerical treatment of problems in atmospheric chemistry

    SciTech Connect

    Aro, C.J.

    1995-09-01

    Atmospheric chemical-radiative-transport (CRT) models are vital in performing research on atmospheric chemical change. Even with the enormous computing capability delivered by massively parallel systems, extended three dimensional CRT simulations are still not computationally feasible. The major obstacle in a CRT model is the nonlinear ODE system describing the chemical kinetics in the model. These ODE systems are usually very stiff and account for anywhere from 75% to 90% of the CPU time required to run a CRT model. In this study, a simple explicit class of time stepping method is developed and demonstrated to be useful in treating chemical ODE systems without the use of a Jacobian matrix. These methods, called preconditioned time differencing methods, are tested on small mathematically idealized problems, box model problems, and full 2-D and 3-D CRT models. The methods are found to be both fast and memory efficient. Studies are performed on both vector and parallel systems. The preconditioned time differencing methods are established as a viable alternative to the more common backward differentiation formulas in terms of CPU speed across architectural platforms.

  3. A photochemical reactor for studies of atmospheric chemistry

    NASA Astrophysics Data System (ADS)

    Nilsson, E. J. K.; Eskebjerg, C.; Johnson, M. S.

    A photochemical reactor for studies of atmospheric kinetics and spectroscopy has been built at the Copenhagen Center for Atmospheric Research. The reactor consists of a vacuum FTIR spectrometer coupled to a 100 L quartz cylinder by multipass optics mounted on electropolished stainless steel end flanges, surrounded by UV-A, UV-C and broadband sun lamps in a temperature-controlled housing. The combination of a quartz vessel and UV-C lamps allows higher concentrations of O( 1D) and OH than can be generated by similar chambers. The reactor is able to produce radical concentrations of ca. 8 × 10 11 cm -3 for OH, 3 × 10 6 cm -3 for O( 1D), 3.3 × 10 10 cm -3 for O( 3P) and 1.6 × 10 12 cm -3 for Cl. The reactor can be operated at pressures from 10 -3 to 10 3 mbar and temperatures from 240 to 330 K. As a test of the system we have studied the reaction CHCl 3 + Cl using the relative rate technique and find k CHCl3+Cl/k CH4+Cl = 1.03 ± 0.11, in good agreement with the accepted value.

  4. Laboratory studies of heterogeneous chemistry relevant to the polar atmosphere

    SciTech Connect

    Sodeau, J.R.

    1996-10-01

    The heterogeneous interactions of the stratospheric reservoir species HCl, ClONO{sub 2} and N{sub 2}O{sub 5} with water-rich, polar stratospheric particle mimics represent key, initial steps in the chemistry associated with Antarctic ozone depletion. Using both FTIR spectroscopic and mass spectrometric techniques, we have demonstrated the crucial role of solvated ionic species in the process and shown that the mechanisms can procede by an S{sub N}2-type nucleophilic attack of the oxygen atom from the surface water molecule upon the most accessible electrophilic site of the adsorbing reactant. In contrast to the ozone {open_quotes}hole{close_quotes}, the detailed chemical mechanisms of other polar phenomena, such as {open_quotes}sudden{close_quotes} tropospheric ozone loss over the Arctic and the OH radical {open_quotes}morning burst{close_quotes} measured in the lower Antarctic stratosphere, are little understood. However, cold, condensed matter from a variety of origins is known to exist in both regions. Therefore we shall also report our recent photochemical results pertinent to low-temperature heterogeneous aspects of both issues.

  5. "Holes" in Student Understanding: Addressing Prevalent Misconceptions regarding Atmospheric Environmental Chemistry

    ERIC Educational Resources Information Center

    Kerr, Sara C.; Walz, Kenneth A.

    2007-01-01

    There is a misconception among undergraduate students that global warming is caused by holes in the ozone layer. In this study, we evaluated the presence of this and other misconceptions surrounding atmospheric chemistry that are responsible for the entanglement of the greenhouse effect and the ozone hole in students' conceptual frameworks. We…

  6. ATMOSPHERIC CHEMISTRY OF POTENTIAL EMISSIONS FROM FUEL CONVERSION FACILITIES. A SMOG CHAMBER STUDY

    EPA Science Inventory

    The atmospheric chemistry of chemical species that may be emitted from fuel conversion facilities were studied in smog chambers. Of 17 compounds assessed for ozone-forming potential, 6 compounds were selected along with a control species, propylene, for testing in the presence of...

  7. SPATIAL AND TEMPORAL TRENDS IN THE CHEMISTRY OF ATMOSPHERIC DEPOSITION IN NEW ENGLAND

    EPA Science Inventory

    The authors have evaluated atmospheric deposition related geochemical changes in New England and Quebec by means of (1) transect studies of soil chemistry parallel to pH and metal deposition gradients: and (2) chemical analysis of lake sediments with the following results: (a) Mn...

  8. Theory of planetary atmospheres: an introduction to their physics and chemistry /2nd revised and enlarged edition/

    NASA Astrophysics Data System (ADS)

    Chamberlain, Joseph W.; Hunten, Donald M.

    Theoretical models of planetary atmospheres are characterized in an introductory text intended for graduate physics students and practicing scientists. Chapters are devoted to the vertical structure of an atmosphere; atmospheric hydrodynamics; the chemistry and dynamics of the earth stratosphere; planetary astronomy; ionospheres; airglows, auroras, and aeronomy; and the stability of planetary atmospheres. Extensive graphs, diagrams, and tables of numerical data are provided.

  9. Theory of planetary atmospheres: an introduction to their physics and chemistry /2nd revised and enlarged edition/

    SciTech Connect

    Chamberlain, J.W.; Hunten, D.M.

    1987-01-01

    Theoretical models of planetary atmospheres are characterized in an introductory text intended for graduate physics students and practicing scientists. Chapters are devoted to the vertical structure of an atmosphere; atmospheric hydrodynamics; the chemistry and dynamics of the earth stratosphere; planetary astronomy; ionospheres; airglows, auroras, and aeronomy; and the stability of planetary atmospheres. Extensive graphs, diagrams, and tables of numerical data are provided.

  10. The chemistry of atmospheric bromine. [catalyst for ozone destruction

    NASA Technical Reports Server (NTRS)

    Wofsy, S. C.; Mcelroy, M. B.; Yung, Y. L.

    1975-01-01

    Bromine may act as a catalyst for recombination of ozone and could be more efficient than either nitric oxide or chlorine. The lower atmosphere contains small concentrations of gaseous bromine produced in part by marine activity and volatilization of particulate material released during the combustion of leaded gasoline, with an additional contribution due to the use of methyl bromide as an agricultural fumigant. Observations by Lazrus et al., (1975) indicate small concentrations of bromine, about 10 to the -11th power (v/v), in the contemporary stratosphere and appear to imply a reduction of approximately 0.3% in the global budget of O3. Estimates are given for future reductions in O3 which might occur if the use of CH3Br as an agricultural fumigant were to continue to grow at present rates.

  11. Atmospheric chemistry: Laboratory studies of kinetics of important reactions

    NASA Astrophysics Data System (ADS)

    Smith, S. J.

    Experiments to measure the rate constants for some reactions of the atmospherically important nitrate radical (NO3) are described using the discharge-flow technique. The nitrate radical was monitored by optical absorption at lambda = 662 nm. The reactions of NO3 with some stable organic and inorganic substrates are reported. The temperature dependences of some of the rate constants were also determined (298 less than T less than 523 K). In most cases, computer simulation was used to extract the rate constant for the primary process because the time-dependent behavior of (NO3) was affected by secondary reactions of NO3 with products of the primary interaction. The Arrhenius parameter for the reactions of NO3 with CH3CH3, CH2CH2, CH3OH, CHCl3, and HCl were determined. The activation energies for the reactions studied between NO3 and some alkynes are presented along with the corresponding pre-exponential factors. Some reactions were studied at room temperature (298 plus or minus 2 K) only and the rate constants found (in units of cubic cm/molecule sec) are: buta-1,3-diene (1.8 x 10 (exp -13), isobutene (2.8 x 10 (exp -13), HBr (1.3 x 10 (exp -15) and hex-2-yne (3.0 x 10 (exp -14). Non-Arrhenius behavior was found in the reactions of NO3 with n-butane, isobutane and propene. The empirical variation of these rate constants with temperature is presented. The curvature of the Arrhenius plots is discussed in terms of (1) a temperature-dependent pre-exponential factor, and (2) the possibility that two competing channels, possessing differing activation energies, exist for each reaction. The atmospheric implications of these reactions are discussed with reference to the nighttime production of nitric acid and the importance of the these reactions as loss processes for NO3.

  12. 1D Chemical Modeling of coupled snow-atmosphere chemistry at Dome C Antarctica

    NASA Astrophysics Data System (ADS)

    Gil, Jaime E.; Thomas, Jennie; von Glasgow, Roland; Bekki, Slimane; Kukui, Alexandre; Frey, Markus; Jourdain, Bruno; Kerbrat, Michel; Genthon, Christophe; Preuknert, Susanne; Legrand, Michel

    2013-04-01

    High levels of nitrogen oxides NOx (NOx=NO+NO2) generated by the photolysis of nitrate present in surface snow profoundly impact atmospheric composition and oxidizing capacity in the Antarctic boundary layer. In particular, NOx emissions from sunlit snow increase OH values by effectively recycling HO2 to OH. In order to better characterize this chemistry the OPALE campaign was conducted in December 2011/January 2012 at Dome C, Antarctica (altitude of 3,233 meters, 75 ° S, 123 ° E). The campaign included boundary layer profiling, measurements of the physical properties of snow, as well as a comprehensive suite of atmospheric chemistry measurements (including NOx, HONO, OH and RO2, H2O2, CH2O, O3). We present results using the 1-D coupled snow-boundary layer model MISTRA-SNOW in combination with observations made during the measurement campaign to understand this chemistry. The model includes both chemistry at the surface of snow grains (aqueous chemistry), in firn air (gas phase chemistry), and gas/aerosol chemistry in the boundary layer. Model predictions of NOx mixing ratios using a model sensitivity analysis approach are presented. The model was initialized using measured snow properties, including temperature, density, and snow grain size. In addition, the model dynamics are driven using the measured surface temperature at Dome C. To calculate the rate of snowpack ventilation, measured wind speeds during the campaign were used. The model was run varying the amount of nitrate and bromide available for reaction at the surface of snow grains and results are compared to measurements made in the atmospheric boundary from 2-4 January 2012. We test the hypothesis that very low concentrations of bromine may alter the ratio of NO/NO2. We also investigate the influence of NOx emissions from snow, and bromine (if present), on OH concentrations in the boundary layer on the Antarctic plateau.

  13. Plant surface reactions: an ozone defence mechanism impacting atmospheric chemistry

    NASA Astrophysics Data System (ADS)

    Jud, W.; Fischer, L.; Canaval, E.; Wohlfahrt, G.; Tissier, A.; Hansel, A.

    2015-07-01

    Elevated tropospheric ozone concentrations are considered a toxic threat to plants, responsible for global crop losses with associated economic costs of several billion dollars per year. Plant injuries have been linked to the uptake of ozone through stomatal pores and oxidative damage of the internal leaf tissue. But a striking question remains: how much ozone effectively enters the plant through open stomata and how much is lost by chemical reactions at the plant surface? In this laboratory study we could show that semi-volatile organic compounds exuded by the glandular trichomes of different Nicotiana tabacum varieties are an efficient ozone sink at the plant surface. In our experiments, different diterpenoid compounds were responsible for a strongly variety dependent ozone uptake of plants under dark conditions, when stomatal pores are almost closed. Surface reactions of ozone were accompanied by prompt release of oxygenated volatile organic compounds, which could be linked to the corresponding precursor compounds: ozonolysis of cis-abienol (C20H34O) - a diterpenoid with two exocyclic double bonds - caused emissions of formaldehyde (HCHO) and methyl vinyl ketone (C4H6O). The ring-structured cembratrien-diols (C20H34O2) with three endocyclic double bonds need at least two ozonolysis steps to form volatile carbonyls such as 4-oxopentanal (C5H8O2), which we could observe in the gas phase, too. Fluid dynamic calculations were used to model ozone distribution in the diffusion limited leaf boundary layer under daylight conditions. In the case of an ozone-reactive leaf surface, ozone gradients in the vicinity of stomatal pores are changed in such a way, that ozone flux through the open stomata is strongly reduced. Our results show that unsaturated semi-volatile compounds at the plant surface should be considered as a source of oxygenated volatile organic compounds, impacting gas phase chemistry, as well as efficient ozone sink improving the ozone tolerance of plants.

  14. Atmospheric chemistry of carboxylic acids: microbial implication versus photochemistry

    NASA Astrophysics Data System (ADS)

    Vaïtilingom, M.; Charbouillot, T.; Deguillaume, L.; Maisonobe, R.; Parazols, M.; Amato, P.; Sancelme, M.; Delort, A.-M.

    2011-08-01

    The objective of this work was to compare experimentally the contribution of photochemistry vs. microbial activity to the degradation of carboxylic acids present in cloud water. For this, we selected 17 strains representative of the microflora existing in real clouds and worked on two distinct artificial cloud media that reproduce marine and continental cloud chemical composition. Photodegradation experiments with hydrogen peroxide (H2O2) as a source of hydroxyl radicals were performed under the same microcosm conditions using two irradiation systems. Biodegradation and photodegradation rates of acetate, formate, oxalate and succinate were measured on both media at 5 °C and 17 °C and were shown to be on the same order of magnitude (around 10-10-10-11 M s-1). The chemical composition (marine or continental origin) had little influence on photodegradation and biodegradation rates while the temperature shift from 17 °C to 5 °C decreased biodegradation rates of a factor 2 to 5. In order to test other photochemical scenarios, theoretical photodegradation rates were calculated considering hydroxyl (OH) radical concentration values in cloud water estimated by cloud chemistry modelling studies and available reaction rate constants of carboxylic compounds with both hydroxyl and nitrate radicals. Considering high OH concentration ([OH] = 1 × 10-12 M) led to no significant contribution of microbial activity in the destruction of carboxylic acids. On the contrary, for lower OH concentration (at noon, [OH] = 1 × 10-14 M), microorganisms could efficiently compete with photochemistry and in similar contributions than the ones estimated by our experimental approach. Combining these two approaches (experimental and theoretical), our results led to the following conclusions: oxalate was only photodegraded; the photodegradation of formate was usually more efficient than its biodegradation; the biodegradation of acetate and succinate seemed to exceed their photodegradation.

  15. Projects in the Physcial Chemistry Laboratory: Letting the Students Choose

    NASA Astrophysics Data System (ADS)

    Buckley, Paul D.; Jolley, Kenneth W.; Watson, Ian D.

    1997-05-01

    In a twelve week Physical Chemistry laboratory course half the time is spent on a standard set of rotation experiments and half on a project of the students own choosing. The students are told that they must only use equipment available within the department and chemicals that are either in the department or which can be ordered on a strictly limited budget. These restriction provide valuable experience in planning research work using limited resources. Initially the projects are based on an article in the literature or on an experiment in a Laboratory Manual and only after successfully repeating the published procedure is the project extended into new areas. Each student gives a short talk outlining the planned experiments before the experimental work begins and/or one presenting the results at the end. A positive attitude to problem solving is encouraged. Successful problem solving is identified through regular review by the class of progress in each project. Students report finding the project a rewarding and challenging experience. The laboratory course is now a more satisfying experience for both staff and students.

  16. Spiers Memorial Lecture. Introductory lecture: chemistry in the urban atmosphere.

    PubMed

    Baltensperger, Urs

    2016-07-18

    The urban atmosphere is characterised by a multitude of complex processes. Gaseous and particulate components are continuously emitted into the atmosphere from many different sources. These components are then dispersed in the urban atmosphere via turbulent mixing. Numerous chemical reactions modify the gas phase chemistry on multiple time scales, producing secondary pollutants. Through partitioning, the chemical and physical properties of the aerosol particles are also constantly changing as a consequence of dispersion and gas phase chemistry. This review presents an overview of the involved processes, focusing on the contributions presented at this conference and putting them into a broader context. Advanced methods for aerosol source apportionment are presented as well, followed by some aspects of health effects related to air pollution. PMID:27247983

  17. Variations in school playground and classroom atmospheric particulate chemistry

    NASA Astrophysics Data System (ADS)

    Moreno, Teresa; Rivas, Ioar; Bouso, Laura; Viana, Mar; Jones, Tim; Àlvarez-Pedrerol, Mar; Alastuey, Andrés; Sunyer, Jordi; Querol, Xavier

    2014-07-01

    The chemical analysis of 553 school playground and classroom PM2.5 filters collected during the BREATHE sampling campaign in Barcelona, Spain, reveals a remarkable degree of spatial and temporal variability in ambient PM composition. Classroom air quality shows average PM2.5 concentrations of 37 μg m-3 (28% higher than outdoors), with much of this mass comprising carbon (including abundant cotton fibres), blackboard chalk particles and silicates. Where sandy playgrounds are present these exert a major influence on inhalable PM2.5 concentrations both indoors and outdoors. Throughout the city there is widespread contamination by metalliferous traffic particles, especially at schools located close to major urban highways where outdoor EC levels can be an order of magnitude higher than in peripheral, green belt schools. Penetration into the classroom of outdoor EC, ammonium sulphate and anthropogenic metals such as Cu, Sn, Sb, Zn and V is pervasive, especially during warmer months. In contrast, levels of nitrate and ammonium are much higher outdoors than in the classroom, especially during winter. During their work and play, schoolchildren across the city respire in a diversity of chemically differing atmospheric microenvironments.

  18. Mars Atmospheric Chemistry in Electrified Dust Devils and Storms

    NASA Technical Reports Server (NTRS)

    Farrell, W. M.; Delory, G. T.; Atreya, S. K.; Wong, A.-S.; Renno, N. O.; Sentmann, D. D.; Marshall, J. G.; Cummer, S. A.; Rafkin, S.; Catling, D.

    2005-01-01

    Laboratory studies, simulations and desert field tests all indicate that aeolian mixing dust can generate electricity via contact electrification or "triboelectricity". In convective structures like dust devils or storms, grain stratification (or charge separation) occurs giving rise to an overall electric dipole moment to the aeolian feature, similar in nature to the dipolar electric field generated in terrestrial thunderstorms. Previous simulation studies [1] indicate that this storm electric field on Mars can approach atmospheric breakdown field strength of 20 kV/m. In terrestrial dust devils, coherent dipolar electric fields exceeding 20 kV/m have been measured directly via electric field instrumentation. Given the expected electrostatic fields in Martian dust devils and storms, electrons in the low pressure CO2 gas can be energized via the electric field to values exceeding the electron dissociative attachment energy of both CO2 and H2O, resulting in the formation of new chemical products CO and O- and OH and H- within the storm. Using a collisional plasma physics model we present a calculation of the CO/O- and OH/H- reaction and production rates. We demonstrate that these rates vary geometrically with ambient electric field, with substantial production of dissociative products when fields approach breakdown levels of 20-30 kV/m.

  19. Atmospheric Chemistry: Laboratory Studies of Kinetics of Important Reactions.

    NASA Astrophysics Data System (ADS)

    Smith, S. J.

    Available from UMI in association with The British Library. Requires signed TDF. This thesis describes the experiments to measure the rate constants for some reactions of the atmospherically important nitrate radical (NO_3) using the discharge-flow technique. The nitrate radical was monitored by optical absorption at lambda = 662 nm. The reactions of NO_3 with some stable organic and inorganic substrates are reported. The temperature dependences of some of the rate constants have also been determined (298 < T < 523 K). In most cases, computer simulation was used to extract the rate constant for the primary process because the time-dependent behaviour of (NO_3) was affected by secondary reactions of NO_3 with products of the primary interaction. The Arrhenius parameter in parentheses (E _{rm a}/kJ mol^ {-1}, A/cm^3 molecule ^{-1}s^ {-1} respectively) for the following reactions have been determined: ethane (37, 6.7 times 10^{-12}), ethylene (25.8, 6.3 times 10^ {-12}), CH_3OH (21.3, 1.2 times 10^ {-12}), CHCiota_3 (23.4, 8.6 times 10 ^{-13}) and HCl (27.7, 4 times 10^{-12}). The activation energies for the reactions studied between NO_3 and some alkynes are represented well by the value 25 +/- 3 kJ mol^{-1} and the corresponding pre-exponential factors (expressed as ln(10 ^{13}A/cm^3 molecule^{-1}s ^{-1}) are as follows: C_2H_2 (1.6 +/- 1.4), C_3H _4 (5.0 +/- 1.4), 1-C_4H_6 (5.8 +/- 1.0), 1-C_5 H_8 (5.7 +/- 0.6) and 1-C_6H _{10} (4.5 +/- 0.4). Some reactions were studied at room temperature _3(298 +/- 2 K) only and the rate constants found (in units of cm ^3 molecule^{ -1}s^{-1}) are: buta-1,3-diene (1.8 times 10 ^{-13}), isobutene (2.8 times 10^{-13 }), HBr (1.3 times 10 ^{-15}) and hex-2-yne (3.0 times 10^{-14 }). Non-Arrhenius behaviour was found in the reactions of NO_3 with n-butane, isobutane and propene. The empirical variation of these rate constants with temperature is well represented by the three parameter expressions:. k(T) = 1.2 times 10 ^{-46}T^{11

  20. Non-OH chemistry in oxidation flow reactors for the study of atmospheric chemistry systematically examined by modeling

    NASA Astrophysics Data System (ADS)

    Peng, Z.; Day, D. A.; Ortega, A. M.; Palm, B. B.; Hu, W. W.; Stark, H.; Li, R.; Tsigaridis, K.; Brune, W. H.; Jimenez, J. L.

    2015-09-01

    Oxidation flow reactors (OFRs) using low-pressure Hg lamp emission at 185 and 254 nm produce OH radicals efficiently and are widely used in atmospheric chemistry and other fields. However, knowledge of detailed OFR chemistry is limited, allowing speculation in the literature about whether some non-OH reactants, including several not relevant for tropospheric chemistry, may play an important role in these OFRs. These non-OH reactants are UV radiation, O(1D), O(3P), and O3. In this study, we investigate the relative importance of other reactants to OH for the fate of reactant species in OFR under a wide range of conditions via box modeling. The relative importance of non-OH species is less sensitive to UV light intensity than to relative humidity (RH) and external OH reactivity (OHRext), as both non-OH reactants and OH scale roughly proportional to UV intensity. We show that for field studies in forested regions and also the urban area of Los Angeles, reactants of atmospheric interest are predominantly consumed by OH. We find that O(1D), O(3P), and O3 have relative contributions to VOC consumption that are similar or lower than in the troposphere. The impact of O atoms can be neglected under most conditions in both OFR and troposphere. Under "pathological OFR conditions" of low RH and/or high OHRext, the importance of non-OH reactants is enhanced because OH is suppressed. Some biogenics can have substantial destructions by O3, and photolysis at non-tropospheric wavelengths (185 and 254 nm) may also play a significant role in the degradation of some aromatics under pathological conditions. Working under low O2 with the OFR185 mode allows OH to completely dominate over O3 reactions even for the biogenic species most reactive with O3. Non-tropospheric VOC photolysis may have been a problem in some laboratory and source studies, but can be avoided or lessened in future studies by diluting source emissions and working at lower precursor concentrations in lab studies, and

  1. 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.

  2. Atmospheric chemistry of carboxylic acids: microbial implication versus photochemistry

    NASA Astrophysics Data System (ADS)

    Vaïtilingom, M.; Charbouillot, T.; Deguillaume, L.; Maisonobe, R.; Parazols, M.; Amato, P.; Sancelme, M.; Delort, A.-M.

    2011-02-01

    Clouds are multiphasic atmospheric systems in which the dissolved organic compounds, dominated by carboxylic acids, are subject to multiple chemical transformations in the aqueous phase. Among them, solar radiation, by generating hydroxyl radicals (•OH), is considered as the main catalyzer of the reactivity of organic species in clouds. We investigated to which extent the active biomass existing in cloud water represents an alternative route to the chemical reactivity of carboxylic acids. Pure cultures of seventeen bacterial strains (Arthrobacter, Bacillus, Clavibacter, Frigoribacterium, Pseudomonas, Sphingomonas and Rhodococcus), previously isolated from cloud water and representative of the viable community of clouds were first individually incubated in two artificial bulk cloud water solutions at 17 °C and 5 °C. These solutions mimicked the chemical composition of cloud water from "marine" and "continental" air masses, and contained the major carboxylic acids existing in the cloud water (i.e. acetate, formate, succinate and oxalate). The concentrations of these carboxylic compounds were monitored over time and biodegradation rates were determined. In average, they ranged from 2 ×10-19 for succinate to 1 × 10-18 mol cell-1 s-1 for formate at 17 °C and from 4 × 10-20 for succinate to 6 × 10-19 mol cell-1 s-1 for formate at 5 °C, with no significant difference between "marine" and "continental" media. In parallel, irradiation experiments were also conducted in these two artificial media to compare biodegradation and photodegradation of carboxylic compounds. To complete this comparison, the photodegradation rates of carboxylic acids by •OH radicals were calculated from literature data. Inferred estimations suggested a significant participation of microbes to the transformation of carboxylic acids in cloud water, particularly for acetate and succinate (up to 90%). Furthermore, a natural cloud water sample was incubated (including its indigenous microflora

  3. The ENVISAT Atmospheric Chemistry mission (GOMOS, MIPAS and SCIAMACHY) -Processing status and data availability

    NASA Astrophysics Data System (ADS)

    Dehn, Angelika; Brizzi, G.; Barrot, G.; Bovensmann, H.; Canela, M.; Fehr, T.; Laur, H.; Lichtenberg, G.; Niro, F.; Perron, G.; Raspollini, P.; Saavedra de Miguel, L.; Scarpino, G.; Vogel, P.

    The atmospheric chemistry instruments on board the ENVISAT platform (GOMOS, MIPAS and SCIAMACHY) provide a unique dataset of geophysical parameters (e.g.: trace gases, clouds, and aerosol) that allows a comprehensive characterization of the atmosphere's chemical and climatological processes [1]. These instruments started to provide significant science data shortly after the launch of the ENVISAT satellite (March 2002). At the time of writing this paper, these instruments and the whole payload modules are fully working and are well beyond the expected lifetime of 5 years. In addition the orbit control strategy of the platform will be modified starting from 2010, in order to extend the mission lifetime up to 2013 [2]. This means that if no instrument problems will appear, the ENVISAT atmospheric sensors will provide at the end of their life, three separated, but complementary datasets of the most important atmospheric state parameters, spanning a time interval of about 11 years. This represents an extraordinary source of information for the scientific user community, both for the completeness and quality of the data and for the extent of the dataset. The aim of this paper is to present the actual status of the ESA operational atmospheric chemistry dataset provided by the three ENVISAT atmospheric chemistry instruments and the future evolution. The processing and reprocessing status will be described in details for each instrument. The outcomes of the geophysical validation and the planned validation activities will be discussed. Finally the data availability and the source of information will be specified. [1] H. Nett, J. Frerick, T. Paulsen, and G. Levrini, "The atmospheric instruments and their applications: GOMOS, MIPAS and SCIAMACHY", ESA Bulletin (ISSN 0376-4265), No. 106, p. 77 -87 (2001) [2] J. Frerick, B. Duesmann, and M. Canela, "2010 and beyond -The ENVISAT mission extension", Proc. `Envisat Symposium 2007', Montreux, Switzerland, 23-27 April 2007 (ESA SP

  4. The ENVISAT Atmospheric Chemistry mission (GOMOS, MIPAS and SCIAMACHY) - Processing status and data availability

    NASA Astrophysics Data System (ADS)

    Niro, F.

    2009-04-01

    The atmospheric chemistry instruments on board the ENVISAT platform (GOMOS, MIPAS and SCIAMACHY) provide a unique dataset of geophysical parameters (e.g.: trace gases, clouds, and aerosol) that allows a comprehensive characterization of the atmosphere's chemical and climatological processes [1]. These instruments started to provide significant science data shortly after the launch of the ENVISAT satellite (March 2002). At the time of writing this paper, these instruments and the whole payload modules are fully working and are well beyond the expected lifetime of 5 years. In addition the orbit control strategy of the platform will be modified starting from 2010, in order to extend the mission lifetime up to 2013 [2]. This means that if no instrument problems will appear, the ENVISAT atmospheric sensors will provide at the end of their life, three separated, but complementary datasets of the most important atmospheric state parameters, spanning a time interval of about 11 years. This represents an extraordinary source of information for the scientific user community, both for the completeness and quality of the data and for the extent of the dataset. The aim of this paper is to present the actual status of the ESA operational atmospheric chemistry dataset provided by the three ENVISAT atmospheric chemistry instruments and the future evolution. The processing and reprocessing status will be described in details for each instrument. The outcomes of the geophysical validation and the planned validation activities will be discussed. Finally the data availability and the source of information will be specified. [1] H. Nett, J. Frerick, T. Paulsen, and G. Levrini, "The atmospheric instruments and their applications: GOMOS, MIPAS and SCIAMACHY", ESA Bulletin (ISSN 0376-4265), No. 106, p. 77 - 87 (2001) [2] J. Frerick, B. Duesmann, and M. Canela, "2010 and beyond - The ENVISAT mission extension", Proc. ‘Envisat Symposium 2007', Montreux, Switzerland, 23-27 April 2007 (ESA

  5. Influence of ab initio chemistry models on simulations of the Ionian atmosphere

    NASA Astrophysics Data System (ADS)

    Parsons, Neal; Levin, Deborah A.; Walker, Andrew C.; Moore, Chris H.; Goldstein, David B.; Varghese, Philip L.; Trafton, Laurence

    2014-09-01

    There is significant scientific interest in simulating the unique atmospheric conditions on the Jovian moon Io that range from cold surface temperatures to hyperthermal interactions which possibly supply the Jovian plasma torus. The Direct Simulation Monte Carlo (DSMC) method is well suited to model the rarefied, predominantly SO2, Ionian atmosphere. High speed collisions between SO2 and the hypervelocity O atoms and ions that compose the plasma torus are a significant mechanism in determining the composition of the atmosphere; therefore, high-fidelity modeling of their interactions is crucial to the accuracy of such simulations. Typically, the Total Collision Energy (TCE) model is used to determine molecular dissociation probabilities and the Variable Hard Sphere (VHS) model is used to determine collision cross sections. However, the parameters for each of these baseline models are based on low-temperature experimental data and thus have unknown reliability for the hyperthermal conditions in the Ionian atmosphere. Recently, Molecular Dynamics/Quasi-Classical Trajectory (MD/QCT) studies have been conducted to generate accurate collision and chemistry models for the SO2-O collision pair in order to replace the baseline models. However, the influence of MD/QCT models on Ionian simulations compared to the previously used models is not well understood. In this work, 1D simulations are conducted using both the MD/QCT-based and baseline models in order to determine the effect of MD/QCT models on Ionian simulations. It is found that atmospheric structure predictions are highly sensitive to the chemistry and collision models. Specifically, the MD/QCT model predicts approximately half the SO2 atmospheric dissociation due to O and O+ bombardment compared to TCE models, and also predicts a temperature rise due to plasma heating further from the Ionian surface than the existing baseline methodologies. These findings indicate that the accurate MD/QCT chemistry and collision

  6. Science Project Ideas about Kitchen Chemistry. Revised Edition.

    ERIC Educational Resources Information Center

    Gardner, Robert

    This book presents science experiments that can be conducted in the kitchen. Contents include: (1) "Safety First"; (2) "Chemistry in and Near the Kitchen Sink"; (3) "Chemistry in the Refrigerator"; (4) "Chemistry on the Stove"; (5) "Chemistry on the Kitchen Counter"; and (6) "Further Reading and Internet Addresses." (YDS)

  7. Variational fine-grained data assimilation schemes for atmospheric chemistry transport and transformation models

    NASA Astrophysics Data System (ADS)

    Penenko, Alexey; Penenko, Vladimir; Tsvetova, Elena

    2015-04-01

    The paper concerns data assimilation problem for an atmospheric chemistry transport and transformation models. Data assimilation is carried out within variation approach on a single time step of the approximated model. A control function is introduced into the model source term (emission rate) to provide flexibility to adjust to data. This function is evaluated as the minimum of the target functional combining control function norm to a misfit between measured and model-simulated analog of data. This provides a flow-dependent and physically-plausible structure of the resulting analysis and reduces the need to calculate model error covariance matrices that are sought within conventional approach to data assimilation. Extension of the atmospheric transport model with a chemical transformations module influences data assimilation algorithms performance. This influence is investigated with numerical experiments for different meteorological conditions altering convection-diffusion processes characteristics, namely strong, medium and low wind conditions. To study the impact of transformation and data assimilation, we compare results for a convection-diffusion model (without data assimilation), convection-diffusion with assimilation, convection-diffusion-reaction (without data assimilation) and convection-diffusion-reaction-assimilation models. Both high dimensionalities of the atmospheric chemistry models and a real-time mode of operation demand for computational efficiency of the algorithms. Computational issues with complicated models can be solved by using a splitting technique. As the result a model is presented as a set of relatively independent simple models equipped with a kind of coupling procedure. With regard to data assimilation two approaches can be identified. In a fine-grained approach data assimilation is carried out on the separate splitting stages [1,2] independently on shared measurement data. The same situation arises when constructing a hybrid model

  8. Interconnection of reactive oxygen species chemistry across the interfaces of atmospheric, environmental, and biological processes.

    PubMed

    Anglada, Josep M; Martins-Costa, Marilia; Francisco, Joseph S; Ruiz-López, Manuel F

    2015-03-17

    Oxidation reactions are ubiquitous and play key roles in the chemistry of the atmosphere, in water treatment processes, and in aerobic organisms. Ozone (O3), hydrogen peroxide (H2O2), hydrogen polyoxides (H2Ox, x > 2), associated hydroxyl and hydroperoxyl radicals (HOx = OH and HO2), and superoxide and ozonide anions (O2(-) and O3(-), respectively) are the primary oxidants in these systems. They are commonly classified as reactive oxygen species (ROS). Atmospheric chemistry is driven by a complex system of chain reactions of species, including nitrogen oxides, hydroxyl and hydroperoxide radicals, alkoxy and peroxy radicals, and ozone. HOx radicals contribute to keeping air clean, but in polluted areas, the ozone concentration increases and creates a negative impact on plants and animals. Indeed, ozone concentration is used to assess air quality worldwide. Clouds have a direct effect on the chemical composition of the atmosphere. On one hand, cloud droplets absorb many trace atmospheric gases, which can be scavenged by rain and fog. On the other hand, ionic species can form in this medium, which makes the chemistry of the atmosphere richer and more complex. Furthermore, recent studies have suggested that air-cloud interfaces might have a significant impact on the overall chemistry of the troposphere. Despite the large differences in molecular composition, concentration, and thermodynamic conditions among atmospheric, environmental, and biological systems, the underlying chemistry involving ROS has many similarities. In this Account, we examine ROS and discuss the chemical characteristics common to all of these systems. In water treatment, ROS are key components of an important subset of advanced oxidation processes. Ozonation, peroxone chemistry, and Fenton reactions play important roles in generating sufficient amounts of hydroxyl radicals to purify wastewater. Biochemical processes within living organisms also involve ROS. These species can come from pollutants in

  9. Ammonia in the atmosphere: a review on emission sources, atmospheric chemistry and deposition on terrestrial bodies.

    PubMed

    Behera, Sailesh N; Sharma, Mukesh; Aneja, Viney P; Balasubramanian, Rajasekhar

    2013-11-01

    Gaseous ammonia (NH3) is the most abundant alkaline gas in the atmosphere. In addition, it is a major component of total reactive nitrogen. The largest source of NH3 emissions is agriculture, including animal husbandry and NH3-based fertilizer applications. Other sources of NH3 include industrial processes, vehicular emissions and volatilization from soils and oceans. Recent studies have indicated that NH3 emissions have been increasing over the last few decades on a global scale. This is a concern because NH3 plays a significant role in the formation of atmospheric particulate matter, visibility degradation and atmospheric deposition of nitrogen to sensitive ecosystems. Thus, the increase in NH3 emissions negatively influences environmental and public health as well as climate change. For these reasons, it is important to have a clear understanding of the sources, deposition and atmospheric behaviour of NH3. Over the last two decades, a number of research papers have addressed pertinent issues related to NH3 emissions into the atmosphere at global, regional and local scales. This review article integrates the knowledge available on atmospheric NH3 from the literature in a systematic manner, describes the environmental implications of unabated NH3 emissions and provides a scientific basis for developing effective control strategies for NH3. PMID:23982822

  10. Atmospheric Infrared Sounder (AIRS) Project Status

    NASA Technical Reports Server (NTRS)

    Pagano, Thomas S.

    2006-01-01

    This viewgraph presentation reviews the status of the Atmospheric Infrared Sounder (AIRS) and the Advanced Microwave Sounding Unit (AMSU). These instruments are on board the EOS Aqua Spacecraft that was launched May 4, 2002. The instruments are working normally. The objectives of the mission were to improve weather forecasting, assist in climate studies, and provide information as to the composition of Earth's atmosphere. The Aqua spacecraft is operating normally, the the primary life-limiting resource is fuel for maneuvers. The presentation also contains charts indicating who are using the data. There is information on the type of data available, and the propsal process. Also there is a few views of some of the planned instruments that were made possible in part due to the success of AIRS.

  11. Where is the equator? A definition based on the atmosphere and its implications for atmospheric chemistry and climate

    NASA Astrophysics Data System (ADS)

    Holmes, C. D.; Prather, M. J.

    2014-12-01

    The concentration of hydroxyl (OH)—the main sink for the greenhouse gases methane and hydrofluorocarbons—in Earth's northern and southern hemispheres is an important longstanding puzzle in atmospheric chemistry. Observations of methylchloroform imply that there is about 10% more OH-loss in the southern hemisphere. In contrast, global 3-D atmospheric models (CTMs and GCMs) simulate 28 ± 10 % greater OH concentrations and methane loss in the northern hemisphere, according to a recent survey. This apparent shortcoming of many models derives in large part from an inconsistent definition of the hemispheres. For model results, OH concentrations and methane/methylchloroform loss are commonly averaged over the geographic hemispheres, with the geographic equator as the dividing line. For the observations, however, the hemispheres are separated by the atmosphere's circulatory mixing barrier, which rarely coincides with the geographic equator. Instead the barrier to interhemispheric mixing corresponds to the rising branch of the Hadley circulation and follows the seasonal migration of the sun. We use artificial tracers in a CTM to define the atmospheric (as opposed to geographic) hemispheres. We show that the tracer definition corresponds with the Intertropical Convergence Zone (ITCZ) where it is well defined and robust against several different tracer definitions. The atmospheric equator lies at 3°N on average (10°N in boreal summer) and extends as far as 30°N during the South Asian summer monsoon (Figure 1). When methane/methylchloroform loss rates are calculated for the dynamic and time-varying hemispheres, the CTM has just 5% greater loss in the northern hemisphere (Figure 1). Thus, using a definition of atmospheric hemispheres that is consistent with atmospheric circulations reveals that OH distributions in CTMs, while still slightly overestimating northern hemisphere OH, are much closer to observational constraints than has been implied by past work. We also

  12. Ionization chemistry in the H2O-dominant atmospheres of the icy moons

    NASA Astrophysics Data System (ADS)

    Shematovich, V. I.; Johnson, R. E.

    2007-08-01

    The main pathways of the ionization chemistry for pure H2O- and mixed H2O+O2+CO2+NH3+CH4 atmospheres which are representative for neutral and ionized atmospheres of the icy bodies in the Jovian and Saturnian systems are discussed. The gaseous envelopes of the icy moons of the giant planets are formed usually due to the surface radiolysis by the solar UV radiation and energetic magnetospheric plasma (Johnson, 1990). The standard astrochemical UMIST2005 (UDFA05) network is used to infer the main chemical pathways of ionization chemistry in the pure or with admixtures of other volatile molecules water vapor atmospheres. In case of the H2O- dominant atmosphere the parent H2O molecules are easily dissociated and ionized by the solar UVradiation and the energetic magnetospheric electrons. These impact processes result in the formation of the secondary neutral and ionized products - chemically active radicals O and OH, and H+, H2+, O+, OH+, and H2O+ ions. Secondary ions have admixture abundances in the H2O-dominant atmospheres, because they are efficiently transformed to H3O+ hydroxonium ions in the fast ion-molecular reactions. The major H3O+ hydroxonium ion does not chemically interact with other neutrals, and is destroyed in the dissociative recombination with thermal electrons mainly reproducing the chemically simple H, H2, O, and OH species. In case of the mixed H2O+O2-dominant atmosphere corresponding to the near-surface atmospheres of icy moons (Shematovich et al., 2005), the ionization chemistry results in the formation of the second major ion O2+ - because ion of molecular oxygen has the lower ionization potential comparing with other parent species -H2, H2O, CO2. The H+, O+, OH+, and H2O+ ions can be easily converted to O2+ ions through the ion-molecular reactions. In case of significant admixture of molecular hydrogen it is possible to transfer the O2+ ions to the O2H+ ions through the fast reaction with H2 and further to the H3O+ ions through the ion

  13. NASA atmospheric effects of aviation projects: Status and plans

    NASA Technical Reports Server (NTRS)

    Wesoky, Howard L.; Thompson, Anne M.; Stolarski, Richard S.

    1994-01-01

    NASA's Atmospheric Effects of Aviation Project is developing a scientific basis for assessment of the atmospheric impact of subsonic and supersonic aviation. Issues addressed include predicted ozone changes and climatic impact, and related uncertainties. A primary goal is to assist assessments of United Nations scientific organizations and, hence, consideration of emission standards by the International Civil Aviation Organization. Project focus is on simulation of atmospheric processes by computer models, but studies of aircraft operations, laboratory studies, and remote and in situ observations of chemical, dynamic, and radiative processes are also included.

  14. Understanding Differences in Chemistry Climate Model Projections of Stratospheric Ozone

    NASA Technical Reports Server (NTRS)

    Douglass, A. R.; Strahan, S. E.; Oman, L. D.; Stolarski, R. S.

    2014-01-01

    Chemistry climate models (CCMs) are used to project future evolution of stratospheric ozone as concentrations of ozone-depleting substances (ODSs) decrease and greenhouse gases increase, cooling the stratosphere. CCM projections exhibit not only many common features but also a broad range of values for quantities such as year of ozone return to 1980 and global ozone level at the end of the 21st century. Multiple linear regression is applied to each of 14 CCMs to separate ozone response to ODS concentration change from that due to climate change. We show that the sensitivity of lower stratospheric ozone to chlorine change Delta Ozone/Delta inorganic chlorine is a near-linear function of partitioning of total inorganic chlorine into its reservoirs; both inorganic chlorine and its partitioning are largely controlled by lower stratospheric transport. CCMs with best performance on transport diagnostics agree with observations for chlorine reservoirs and produce similar ozone responses to chlorine change. After 2035, differences in Delta Ozone/Delta inorganic chlorine contribute little to the spread in CCM projections as the anthropogenic contribution to inorganic chlorine becomes unimportant. Differences among upper stratospheric ozone increases due to temperature decreases are explained by differences in ozone sensitivity to temperature change Delta Ozone/Delta T due to different contributions from various ozone loss processes, each with its own temperature dependence. Ozone decrease in the tropical lower stratosphere caused by a projected speedup in the Brewer-Dobson circulation may or may not be balanced by ozone increases in the middle- and high-latitude lower stratosphere and upper troposphere. This balance, or lack thereof, contributes most to the spread in late 21st century projections.

  15. Complexes and clusters of water relevant to atmospheric chemistry: H2O complexes with oxidants.

    PubMed

    Sennikov, Petr G; Ignatov, Stanislav K; Schrems, Otto

    2005-03-01

    Experimental observations and data from quantum chemical calculations on complexes between water molecules and small, oxygen-containing inorganic species that play an important role as oxidants in the atmosphere (O(1D), O(3P), O2(X3sigmag), O2(b1sigmag+), O3, HO, HOO, HOOO, and H2O2) are reviewed, with emphasis on their structure, hydrogen bonding, interaction energies, thermodynamic parameters, and infrared spectra. In recent years, weakly bound complexes containing water have increasingly attracted scientific attention. Water in all its phases is a major player in the absorption of solar and terrestrial radiation. Thus, complexes between water and other atmospheric species may have a perceivable influence on the radiative balance and contribute to the greenhouse effect, even though their concentrations are low. In addition, they can play an important role in the chemistry of the Earth's atmosphere, particularly in the oxidation of trace gases. Apart from gas-phase complexes, the interactions of oxidants with ice surfaces have also received considerable advertency lately due to their importance in the chemistry of snow, ice clouds, and ice surfaces (e.g., ice shields in polar regions). In paleoclimate--respectively paleoenvironmental--studies, it is essential to understand the transfer processes from the atmosphere to the ice surface. Consequently, special attention is being paid here to the intercomparison of the properties of binary complexes and the complexes and clusters of more complicated compositions, including oxidants adsorbed on ice surfaces, where ice is considered a kind of large water cluster. Various facts concerning the chemistry of the Earth's atmosphere (concentration profiles and possible influence on radical reactions in the atmosphere) are discussed. PMID:15799459

  16. MIR station atmospheric chemistry investigations: numerical simulation of the future space experiments

    NASA Astrophysics Data System (ADS)

    Timofeyev, Yuriy M.

    1995-12-01

    Regular, long-term, g1obalscale measurements of atmospheric minor gaseous and aerosol composition (MGAC) by means ofdifferent instruments (PHOENIX, OZONE-MIR, ISTOK-1, DOPI) are planned on board the SPECTR and PRIRODA modules of the Space Station MIR during 1995-1998. The main characteristics of these devices are given. The principal goals of the space experiments are: investigations of the spatial and temporal MGAC variations, comparisons of different space-borne atmospheric chemistry sensors and their intercalibration, validation of the space MGAC measurements using different ground-based station and aircraft data, and studies of the molecular absorption in the atmosphere aimed to enhance an accuracy of radiative transfer atmospheric models. Special attention is . devoted to radiative transfer model (line-mixing, line-shift, line-narrowing, Non-LTE effects). The numerical estimations of the errors of the MGAC vertical profile retrievals using different device data are carried out.

  17. Investigating Titan's Atmospheric Chemistry at Low Temperature with the Titan Haze Simulation Experiment

    NASA Astrophysics Data System (ADS)

    Sciamma-O'Brien, E. M.; Salama, F.

    2012-12-01

    Titan, Saturn's largest satellite, possesses a dense atmosphere (1.5 bar at the surface) composed mainly of N2 and CH4. The solar radiation and electron bombardment from Saturn's magnetosphere induces a complex organic chemistry between these two constituents leading to the production of more complex molecules and subsequently to solid aerosols. These aerosols in suspension in the atmosphere form the haze layers giving Titan its characteristic orange color. Since 2004, the instruments onboard the Cassini orbiter have produced large amounts of observational data, unraveling a chemistry much more complex than what was first expected, particularly in Titan's upper atmosphere. Neutral, positively and negatively charged heavy molecules have been detected in the ionosphere of Titan, including benzene (C6H6) and toluene (C6H5CH3). The presence of these critical precursors of polycyclic aromatic hydrocarbon (PAH) compounds suggests that PAHs might play a role in the production of Titan's aerosols. The aim of the Titan Haze Simulation (THS) experiment, developed at the NASA Ames COSmIC facility, is to study the chemical pathways that link the simple molecules resulting from the first steps of the N2-CH4 chemistry to benzene, and to PAHs and nitrogen-containing PAHs (PANHs) as precursors to the production of solid aerosols. In the THS experiment, Titan's atmospheric chemistry is simulated by plasma in the stream of a supersonic expansion. With this unique design, the gas mixture is cooled to Titan-like temperature (~150K) before inducing the chemistry by plasma discharge. Due to the short residence time of the gas in the plasma discharge, the THS experiment can be used to probe the first and intermediate steps of Titan's chemistry by injecting different gas mixtures in the plasma. The products of the chemistry are detected and studied using two complementary techniques: Cavity Ring Down Spectroscopy and Time-Of-Flight Mass Spectrometry. Thin tholin deposits are also produced

  18. History of Seawater Carbonate Chemistry, Atmospheric CO2, and Ocean Acidification

    NASA Astrophysics Data System (ADS)

    Zeebe, Richard E.

    2012-05-01

    Humans are continuing to add vast amounts of carbon dioxide (CO2) to the atmosphere through fossil fuel burning and other activities. A large fraction of the CO2 is taken up by the oceans in a process that lowers ocean pH and carbonate mineral saturation state. This effect has potentially serious consequences for marine life, which are, however, difficult to predict. One approach to address the issue is to study the geologic record, which may provide clues about what the future holds for ocean chemistry and marine organisms. This article reviews basic controls on ocean carbonate chemistry on different timescales and examines past ocean chemistry changes and ocean acidification events during various geologic eras. The results allow evaluation of the current anthropogenic perturbation in the context of Earth's history. It appears that the ocean acidification event that humans are expected to cause is unprecedented in the geologic past, for which sufficiently well-preserved records are available.

  19. Making a Natural Product Chemistry Course Meaningful with a Mini Project Laboratory

    ERIC Educational Resources Information Center

    Hakim, Aliefman; Liliasari; Kadarohman, Asep; Syah, Yana Maolana

    2016-01-01

    This paper discusses laboratory activities that can improve the meaningfulness of natural product chemistry course. These laboratory activities can be useful for students from many different disciplines including chemistry, pharmacy, and medicine. Students at the third-year undergraduate level of chemistry education undertake the project to…

  20. The ChemViz Project: Using a Supercomputer To Illustrate Abstract Concepts in Chemistry.

    ERIC Educational Resources Information Center

    Beckwith, E. Kenneth; Nelson, Christopher

    1998-01-01

    Describes the Chemistry Visualization (ChemViz) Project, a Web venture maintained by the University of Illinois National Center for Supercomputing Applications (NCSA) that enables high school students to use computational chemistry as a technique for understanding abstract concepts. Discusses the evolution of computational chemistry and provides a…

  1. The THS: Simulating Titan’s atmospheric chemistry at low temperature

    NASA Astrophysics Data System (ADS)

    Sciamma-O'Brien, Ella; Upton, Kathleen T.; Beauchamp, Jack L.; Salama, Farid

    2015-08-01

    In Titan’s atmosphere, composed mainly of N2 (95-98%) and CH4 (2-5%), a complex chemistry occurs at low temperature, and leads to the production of heavy organic molecules and subsequently solid aerosols. Here, we used the Titan Haze Simulation (THS) experiment, an experimental setup developed at the NASA Ames COSmIC simulation facility to study Titan’s atmospheric chemistry at low temperature. In the THS, the chemistry is simulated by plasma in the stream of a supersonic expansion. With this unique design, the gas is cooled to Titan-like temperature (~150K) before inducing the chemistry by plasma, and remains at low temperature in the plasma discharge (~200K). Different N2-CH4-based gas mixtures can be injected in the plasma, with or without the addition of heavier precursors present as trace elements on Titan, in order to monitor the evolution of the chemical growth. Both the gas- and solid phase products resulting from the plasma-induced chemistry can be monitored and analyzed using a combination of complementary in situ and ex situ diagnostics.A recent mass spectrometry study of the gas phase has demonstrated that the THS is a unique tool to probe the first and intermediate steps of Titan’s atmospheric chemistry at Titan-like temperature. In particular, the mass spectra obtained in a N2-CH4-C2H2-C6H6 mixture are relevant for comparison to Cassini’s CAPS-IBS instrument. The results of a complementary study of the solid phase are consistent with the chemical growth evolution observed in the gas phase. Grains and aggregates form in the gas phase and can be jet deposited on various substrates for ex situ analysis. Scanning Electron Microscopy images show that more complex mixtures produce larger aggregates. A DART mass spectrometry analysis of the solid phase has detected the presence of aminoacetonitrile, a precursor of glycine, in the THS aerosols. X-ray Absorption Near Edge Structure (XANES) measurements also show the presence of imine and nitrile

  2. Chemistry-turbulence interactions and mesoscale variability influence the cleansing efficiency of the atmosphere

    NASA Astrophysics Data System (ADS)

    Kaser, L.; Karl, T.; Yuan, B.; Mauldin, R. L.; Cantrell, C. A.; Guenther, A. B.; Patton, E. G.; Weinheimer, A. J.; Knote, C.; Orlando, J.; Emmons, L.; Apel, E.; Hornbrook, R.; Shertz, S.; Ullmann, K.; Hall, S.; Graus, M.; Gouw, J.; Zhou, X.; Ye, C.

    2015-12-01

    The hydroxyl radical (OH) is the most important oxidant in the atmosphere and the primary sink for isoprene, the dominant volatile organic compound emitted by vegetation. Recent research on the atmospheric oxidation capacity in isoprene-dominated environments has suggested missing radical sources leading to significant overestimation of the lifetime of isoprene. Here we report, for the first time, a comprehensive experimental budget of isoprene in the planetary boundary layer based on airborne flux measurements along with in situ OH observations in the Southeast and Central U.S. Our findings show that surface heterogeneity of isoprene emissions lead to a physical separation of isoprene and OH resulting in an effective slowdown in the chemistry. Depending on surface heterogeneity, the intensity of segregation (Is) could locally slow down isoprene chemistry up to 30%. The effect of segregated reactants in the planetary boundary layer on average has an influence on modeled OH radicals that is comparable to that of recently proposed radical recycling mechanisms.

  3. An Extended View of Ozone and Chemistry in the Atmosphere of Mars

    NASA Technical Reports Server (NTRS)

    Smith, Ramsey L.; Fast, Kelly E.; Kostiuk, T.; Lefevre, Frank; Hewagama, Tilak; Livengood, Timothy A.

    2011-01-01

    We present an ongoing effort to characterize chemistry in Mars' atmosphere in multiple seasons on timescales longer than spaceflight missions through coordinated efforts by GSFC's HIPWAC spectrometer and Mars Express SPICAM, archival measurements, and tests/application of photochemical models. The trace species ozone (03) is an effective probe of Mars' atmospheric chemistry because it is destroyed by odd-hydrogen species (HOx, from water vapor photolysis). Observed ozone is a critical test for specific predictions by 3-D photochemical models (spatial, diurnal, seasonal). Coordinated measurements by HIPWAC and SPICAM quantitatively linked mission data to the 23-year GSFC ozone data record and also revealed unanticipated inter-decadal variability of same-season ozone abundances, a possible indicator of changing cloud activity (heterogeneous sink for HOx). A detailed study of long-term conditions is critical to characterizing the predictability of Mars' seasonal chemical behavior, particularly in light of the implications of and the lack of explanation for reported methane behavior.

  4. Global tropospheric experiment at the Hong Kong Atmosphere Chemistry Measurement Station

    NASA Technical Reports Server (NTRS)

    Carroll, Mary Ann; Wang, Tao

    1995-01-01

    The major activities of the Global Tropospheric Experiment at the Hong Kong Atmospheric Chemistry Measurement Station are presented for the period 1 January - 31 December 1995. Activities included data analysis, reduction, and archiving of atmospheric measurements and sampling. Sampling included O3, CO, SO2, NO, TSP, RSP, and ozone column density. A data archive was created for the surface meteorological data. Exploratory data analysis was performed, including examination of time series, frequency distributions, diurnal variations and correlation. The major results have been or will be published in scientific journals as well as presented at conferences/workshops. Abstracts are attached.

  5. Impact of electron chemistry on the structure and composition of Io's atmosphere

    NASA Astrophysics Data System (ADS)

    Smyth, William H.; Wong, M. C.

    2004-09-01

    Two-dimensional model calculations (altitude and solar zenith angle) are performed to investigate the impact of electron chemistry on the composition and structure of Io's atmosphere. The calculations are based upon the model of Wong and Smyth (2000, Icarus 146, 60-74) for Io's SO 2 sublimation atmosphere with the addition of new electron chemistry, where the interactions of the electrons and neutrals are treated in a simple fashion. The model calculations are presented for Io's atmosphere at western elongation (dusk ansa) for both a low-density case (subsolar temperature of 113 K) and a high-density case (subsolar temperature of 120 K). The impact of electron-neutral chemistry on the composition and structure of Io's atmosphere is confined primarily to an interaction layer. The penetration depth of the interaction layer is limited to high altitudes in the thicker dayside atmosphere but reaches the surface in the thinner dayside and/or nightside atmosphere at larger solar zenith angles. Within most of the thicker dayside atmosphere, the column density of SO 2 is not significantly altered by electrons, but in the interaction layer all number densities are significantly altered: SO 2 is reduced, O, SO, S, and O 2 are greatly enhanced, and O, SO, and S become comparable to SO 2 at high altitudes. For the thinner nightside atmosphere, the species number densities are dramatically altered: SO 2 is drastically reduced to the least abundant species of the SO 2 family, SO and O 2 are significantly reduced at all altitudes, and O and S are dramatically enhanced and become the dominant species at all altitudes except near the surface. The interaction layer also defines the location of the emission layer for neutrals excited by electron impact and hence determines the fraction of the total neutral column density that is visible in remote observation. Electron chemistry may also impact the ratio of the equatorial to polar SO 2 column density deduced from Lyman- α images and

  6. Development of an aerosol-chemistry transport model coupled to non-hydrostatic icosahedral atmospheric model (NICAM) through applying a stretched grid system to regional simulations around Japan

    NASA Astrophysics Data System (ADS)

    Goto, D.; Nakajima, T.; Masaki, S.

    2014-12-01

    Air pollution has a great impact on both climate change and human health. One effective way to tackle with these issues is a use of atmospheric aerosol-chemistry models with high-resolution in a global scale. For this purpose, we have developed an aerosol-chemistry model based on a global cloud-resolving model (GCRM), Nonhydrostatic Icosahedral Atmospheric Model (NICAM; Tomita and Satoh, Fluid. Dyn. Res. 2004; Satoh et al., J. Comput. Phys. 2008, PEPS, 2014) under MEXT/RECCA/SALSA project. In the present study, we have simulated aerosols and tropospheric ozone over Japan by our aerosol-chemistry model "NICAM-Chem" with a stretched-grid system of approximately 10 km resolution, for saving the computer resources. The aerosol and chemistry modules are based on Spectral Radiation-Transport Model for Aerosol Species (SPRINTARS; Takemura et al., J. Geophys. Res., 2005) and Chemical AGCM for Study of Atmospheric Environment and Radiative Forcing (CHASER; Sudo et al., J. Geophys. Res., 2002). We found that our model can generally reproduce both aerosols and ozone, in terms of temporal variations (daily variations of aerosols and diurnal variations of ozone). Under MEXT/RECCA/SALSA project, we also have used these results obtained by NICAM-Chem for the assessment of their impact on human health.

  7. Kinetic and photochemical data for atmospheric chemistry reactions of the nitrogen oxides

    NASA Technical Reports Server (NTRS)

    Hampson, R. F., Jr.

    1980-01-01

    Data sheets for thermal and photochemical reactions of importance in the atmospheric chemistry of the nitrogen oxides are presented. For each reaction the available experimental data are summarized and critically evaluated, and a preferred value of the rate coefficient is given. The selection of the preferred value is discussed and an estimate of its accuracy is given. For the photochemical process, the data are summarized, and preferred for the photoabsorption cross section and primary quantum yields are given.

  8. Atmospheric chemistry measurements from the 1992 ASTEX/MAGE Cruise, May 30, 1992 through July 21, 1992, Cruise Number 91-126. Data report

    SciTech Connect

    Carsey, T.P.; Farmer, M.L.; Fischer, C.J.; Mendez, A.; Pszenny, A.A.

    1994-10-01

    The report describes the results of the 1992 ASTEX/MAGE cruise aboard the NOAA R/V MALCOLM BALDRIGE. The cruise was designed to support research sponsored by the NOAA Climate and Global Change Program under: (1) the Marine Sulfur and Climate (MS&C) component of the Atmosphere and Land-Surface Processes Core Project, and (2) the Radiatively Important Trace Species (RITS) component of the Atmospheric Chemistry Core Project. Chemical and meteorological measurements obtained on the cruise include reduced sulfur gases, ozone, carbon monoxide, nitrogen oxides and peroxyacetyl nitrate, rawinsondes, aerosol chemistry, microwave radiometry, vertical wind profiles, heat and water momentum flux, non-methane hydrocarbons, trace metals, aerosol size distributions, aerosol physical properties, and surface water chlorophyll. The report contains a brief description of the experimental apparatus and procedures employed, plus graphic and tabular presentations of the data sets, for most of the data from AOML/OCD investigators.

  9. The Department of Energy`s Atmospheric Chemistry Program: A critical review

    SciTech Connect

    Not Available

    1991-12-31

    In response to a request from the Department of Energy`s (DOE) Office of Health and Environmental Research (OHER), the Committee on Atmospheric Chemistry has reviewed OHER`s Atmospheric Chemistry Program (ACP). This report contains the committee`s evaluation and critique arising from that review. The review process included a two-day symposium held at the National Academy of Sciences on September 25 and 26, 1990, that focused on presenting the ACP`s current components, recent scientific accomplishments, and scientific plans. Following the symposium, committee members met in a one-day executive session to formulate and outline this report. In undertaking this review, OHER and ACP management requested that the committee attempt to answer several specific questions involving the program`s technical capability and productivity, its leadership and organization, and its future direction. These questions are given in the Appendix. This report represents the committee`s response to the questions posed in the Appendix. Chapter I explores the committee`s view of the role that atmospheric chemistry could and should assume within the DOE and its prospective National Energy Strategy. Chapter 2 assesses the current ACP, Chapter 3 presents recommendations for revising and strengthening it, and Chapter 4 restates the committee`s conclusions and recommendations.

  10. Studies in photochemical smog chemistry. 1. Atmospheric chemistry of toulene. 2. Analysis of chemical reaction mechanisms for photochemical smog

    SciTech Connect

    Leone, J.A.

    1985-01-01

    This study focuses on two related topics in the gas phase organic chemistry of importance in urban air pollution. An experimental effort aimed at developing a new explicit reaction mechanism for the atmospheric photooxidation of toluene is described. This mechanism is tested using experimental data from both indoor and outdoor smog chamber facilities. The predictions of the new reaction mechanism are found to be in good agreement with both sets of experimental data. Additional simulations performed with the new mechanism are used to investigate various mechanistic paths. A theoretical analysis of lumped chemical reaction mechanisms for photochemical smog is presented. Included is a description of a new counter species analysis technique which can be used to analyze any complex chemical reaction mechanism. When applied to mechanisms for photochemical smog, this analysis is shown capable of providing answers to previously inaccessible questions such as the relative contributions of individual organics to photochemical ozone formation.

  11. On the relationship between total ozone and atmospheric dynamics and chemistry at mid-latitudes - Part 1: Statistical models and spatial fingerprints of atmospheric dynamics and chemistry

    NASA Astrophysics Data System (ADS)

    Frossard, L.; Rieder, H. E.; Ribatet, M.; Staehelin, J.; Maeder, J. A.; Di Rocco, S.; Davison, A. C.; Peter, T.

    2012-05-01

    We use models for mean and extreme values of total column ozone on spatial scales to analyze "fingerprints" of atmospheric dynamics and chemistry on long-term ozone changes at northern and southern mid-latitudes. The r-largest order statistics method is used for pointwise analysis of extreme events in low and high total ozone (termed ELOs and EHOs, respectively). For the corresponding mean value analysis a pointwise autoregressive moving average model (ARMA) is used. The statistical models include important atmospheric covariates to describe the dynamical and chemical state of the atmosphere: the solar cycle, the Quasi-Biennial Oscillation (QBO), ozone depleting substances (ODS) in terms of equivalent effective stratospheric chlorine (EESC), the North Atlantic Oscillation (NAO), the Antarctic Oscillation (AAO), the El~Niño/Southern Oscillation (ENSO), and aerosol load after the volcanic eruptions of El Chichón and Mt. Pinatubo. The influence of the individual covariates on mean and extreme levels in total column ozone is derived on a grid cell basis. The results show that "fingerprints", i.e., significant influence, of dynamical and chemical features are captured in both the "bulk" and the tails of the ozone distribution, respectively described by means and EHOs/ELOs. While results for the solar cycle, QBO and EESC are in good agreement with findings of earlier studies, unprecedented spatial fingerprints are retrieved for the dynamical covariates.

  12. Variational data assimilation schemes for transport and transformation models of atmospheric chemistry

    NASA Astrophysics Data System (ADS)

    Penenko, Alexey; Penenko, Vladimir; Tsvetova, Elena; Antokhin, Pavel

    2016-04-01

    The work is devoted to data assimilation algorithm for atmospheric chemistry transport and transformation models. In the work a control function is introduced into the model source term (emission rate) to provide flexibility to adjust to data. This function is evaluated as the constrained minimum of the target functional combining a control function norm with a norm of the misfit between measured data and its model-simulated analog. Transport and transformation processes model is acting as a constraint. The constrained minimization problem is solved with Euler-Lagrange variational principle [1] which allows reducing it to a system of direct, adjoint and control function estimate relations. This provides a physically-plausible structure of the resulting analysis without model error covariance matrices that are sought within conventional approaches to data assimilation. High dimensionality of the atmospheric chemistry models and a real-time mode of operation demand for computational efficiency of the data assimilation algorithms. Computational issues with complicated models can be solved by using a splitting technique. Within this approach a complex model is split to a set of relatively independent simpler models equipped with a coupling procedure. In a fine-grained approach data assimilation is carried out quasi-independently on the separate splitting stages with shared measurement data [2]. In integrated schemes data assimilation is carried out with respect to the split model as a whole. We compare the two approaches both theoretically and numerically. Data assimilation on the transport stage is carried out with a direct algorithm without iterations. Different algorithms to assimilate data on nonlinear transformation stage are compared. In the work we compare data assimilation results for both artificial and real measurement data. With these data we study the impact of transformation processes and data assimilation to the performance of the modeling system [3]. The

  13. Atmospheric cloud physics laboratory project study

    NASA Technical Reports Server (NTRS)

    Schultz, W. E.; Stephen, L. A.; Usher, L. H.

    1976-01-01

    Engineering studies were performed for the Zero-G Cloud Physics Experiment liquid cooling and air pressure control systems. A total of four concepts for the liquid cooling system was evaluated, two of which were found to closely approach the systems requirements. Thermal insulation requirements, system hardware, and control sensor locations were established. The reservoir sizes and initial temperatures were defined as well as system power requirements. In the study of the pressure control system, fluid analyses by the Atmospheric Cloud Physics Laboratory were performed to determine flow characteristics of various orifice sizes, vacuum pump adequacy, and control systems performance. System parameters predicted in these analyses as a function of time include the following for various orifice sizes: (1) chamber and vacuum pump mass flow rates, (2) the number of valve openings or closures, (3) the maximum cloud chamber pressure deviation from the allowable, and (4) cloud chamber and accumulator pressure.

  14. NUCLA Circulating Atmospheric Fluidized Bed Demonstration Project

    SciTech Connect

    Not Available

    1992-02-01

    The objective of this DOE Cooperative Agreement is to conduct a cost-shared clean coal technology project to demonstrate the feasibility of circulating fluidized bed combustion technology and to evaluate economic, environmental, and operational benefits of CFB steam generators on a utility scale. At the conclusion of the Phase 2 program, testing related to satisfying these objectives was completed. Data analysis and reporting are scheduled for completion by October 1991. (VC)

  15. Global stratospheric measurements of the isotopologues of methane from the Atmospheric Chemistry Experiment Fourier transform spectrometer

    NASA Astrophysics Data System (ADS)

    Buzan, Eric M.; Beale, Chris A.; Boone, Chris D.; Bernath, Peter F.

    2016-03-01

    This paper presents an analysis of observations of methane and its two major isotopologues, CH3D and 13CH4, from the Atmospheric Chemistry Experiment (ACE) satellite between 2004 and 2013. Additionally, atmospheric methane chemistry is modeled using the Whole Atmospheric Community Climate Model (WACCM). ACE retrievals of methane extend from 6 km for all isotopologues to 75 km for 12CH4, 35 km for CH3D, and 50 km for 13CH4. While total methane concentrations retrieved from ACE agree well with the model, values of δD-CH4 and δ13C-CH4 show a bias toward higher δ compared to the model and balloon-based measurements. Errors in spectroscopic constants used during the retrieval process are the primary source of this disagreement. Calibrating δD and δ13C from ACE using WACCM in the troposphere gives improved agreement in δD in the stratosphere with the balloon measurements, but values of δ13C still disagree. A model analysis of methane's atmospheric sinks is also performed.

  16. Global stratospheric measurements of the isotopologues of methane from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer

    NASA Astrophysics Data System (ADS)

    Buzan, E. M.; Beale, C. A.; Boone, C. D.; Bernath, P. F.

    2015-10-01

    This paper presents an analysis of observations of methane and its two major isotopologues, CH3D and 13CH4 from the Atmospheric Chemistry Experiment (ACE) satellite between 2004 and 2013. Additionally, atmospheric methane chemistry is modeled using the Whole Atmospheric Community Climate Model (WACCM). ACE retrievals of methane extend from 6 km for all isotopologues to 75 km for 12CH4, 35 km for CH3D, and 50 km for 13CH4. While total methane concentrations retrieved from ACE agree well with the model, values of δD-CH4 and δ13C-CH4 show a bias toward higher δ compared to the model and balloon-based measurements. Calibrating δD and δ13C from ACE using WACCM in the troposphere gives improved agreement in δD in the stratosphere with the balloon measurements, but values of δ13C still disagree. A model analysis of methane's atmospheric sinks is also performed.

  17. A comprehensive NMR structural study of Titan aerosol analogs: Implications for Titan's atmospheric chemistry

    NASA Astrophysics Data System (ADS)

    He, Chao; Smith, Mark A.

    2014-11-01

    Titan has a thick atmosphere composed primarily of nitrogen and methane. Complex organic chemistry induced by solar ultraviolet radiation and energetic particles, takes place in Titan's upper atmosphere, producing an optically thick reddish brown carbon based haze encircling this moon. The chemistry in Titan's atmosphere and its resulting chemical structures are still not fully understood in spite of a great many efforts being made. In our previous work, we have investigated the structure of the 13C and 15N labeled, simulated Titan haze aerosols (tholin) by NMR and identified several dominant small molecules in the tholin. Here we report our expanded structural investigation of the bulk of the tholin by more comprehensive NMR study. The NMR results show that the tholin materials are dominated by heavily nitrogenated compounds, in which the macromolecular structures are highly branched polymeric or oligomeric compounds terminated in methyl, amine, and nitrile groups. The structural characteristic suggest that the tholin materials are formed via different copolymerization or incorporation mechanisms of small precursors, such as HCN, CH2dbnd NH, NH3 and C2H2. This study helps to understand the formation process of nitrogenated organic aerosols in Titan's atmosphere and their prebiotic implications.

  18. A New Project-Based Lab for Undergraduate Environmental and Analytical Chemistry

    ERIC Educational Resources Information Center

    Adami, Gianpiero

    2006-01-01

    A new project-based lab was developed for third year undergraduate chemistry students based on real world applications. The experience suggests that the total analytical procedure (TAP) project offers a stimulating alternative for delivering science skills and developing a greater interest for analytical chemistry and environmental sciences and…

  19. The Effect of Web-Based Project Applications on Students' Attitudes towards Chemistry

    ERIC Educational Resources Information Center

    Morgil, Inci; Gungor Seyhan, Hatice; Ural Alsan, Evrim; Temel, Senar

    2008-01-01

    Students perform intensive web-based applications during their education. One of these is project-based application. In this study, the effect of web based project applications on students' attitudes towards chemistry has been investigated. 42 students attending Hacettepe University, Faculty of Education, and Department of Chemistry Education have…

  20. The "Chemistry Is in the News" Project: Can a Workshop Induce a Pedagogical Change?

    ERIC Educational Resources Information Center

    Barak, Miri; Carson, Kathleen M.; Zoller, Uri

    2007-01-01

    Chemistry Is in the News (CIITN) is an innovative project aimed at enhancing higher-order cognitive skills (HOCS) via connecting university-level chemistry to everyday life and real-world issues. The CIITN project and its related Web tools were presented in a workshop to illustrate their conceptual framework, educational potential, and…

  1. The NOx dependence of bromine chemistry in the Arctic atmospheric boundary layer

    NASA Astrophysics Data System (ADS)

    Custard, K. D.; Thompson, C. R.; Pratt, K. A.; Shepson, P. B.; Liao, J.; Huey, L. G.; Orlando, J. J.; Weinheimer, A. J.; Apel, E.; Hall, S. R.; Flocke, F.; Mauldin, L.; Hornbrook, R. S.; Pöhler, D.; General, S.; Zielcke, J.; Simpson, W. R.; Platt, U.; Fried, A.; Weibring, P.; Sive, B. C.; Ullmann, K.; Cantrell, C.; Knapp, D. J.; Montzka, D. D.

    2015-03-01

    Arctic boundary layer nitrogen oxides (NOx = NO2 + NO) are naturally produced in and released from the sunlit snowpack and range between 10 to 100 pptv in the remote background surface layer air. These nitrogen oxides have significant effects on the partitioning and cycling of reactive radicals such as halogens and HOx (OH + HO2). However, little is known about the impacts of local anthropogenic NOx emission sources on gas-phase halogen chemistry in the Arctic, and this is important because these emissions can induce large variability in ambient NOx and thus local chemistry. In this study, a zero-dimensional photochemical kinetics model was used to investigate the influence of NOx on the unique springtime halogen and HOx chemistry in the Arctic. Trace gas measurements obtained during the 2009 OASIS (Ocean-Atmosphere-Sea Ice-Snowpack) field campaign at Barrow, AK were used to constrain many model inputs. We find that elevated NOx significantly impedes gas-phase radical chemistry, through the production of a variety of reservoir species, including HNO3, HO2NO2, peroxyacetyl nitrate (PAN), BrNO2, ClNO2 and reductions in BrO and HOBr, with a concomitant, decreased net O3 loss rate. The effective removal of BrO by anthropogenic NOx was directly observed from measurements conducted near Prudhoe Bay, AK during the 2012 Bromine, Ozone, and Mercury Experiment (BROMEX). Thus, while changes in snow-covered sea ice attributable to climate change may alter the availability of molecular halogens for ozone and Hg depletion, predicting the impact of climate change on polar atmospheric chemistry is complex and must take into account the simultaneous impact of changes in the distribution and intensity of anthropogenic combustion sources. This is especially true for the Arctic, where NOx emissions are expected to increase because of increasing oil and gas extraction and shipping activities.

  2. Heterogeneous chemistry and reaction dynamics of the atmospheric oxidants, O3, NO3, and OH, on organic surfaces.

    PubMed

    Chapleski, Robert C; Zhang, Yafen; Troya, Diego; Morris, John R

    2016-07-01

    Heterogeneous chemistry of the most important atmospheric oxidants, O3, NO3, and OH, plays a central role in regulating atmospheric gas concentrations, processing aerosols, and aging materials. Recent experimental and computational studies have begun to reveal the detailed reaction mechanisms and kinetics for gas-phase O3, NO3, and OH when they impinge on organic surfaces. Through new research approaches that merge the fields of traditional surface science with atmospheric chemistry, researchers are developing an understanding for how surface structure and functionality affect interfacial chemistry with this class of highly oxidizing pollutants. Together with future research initiatives, these studies will provide a more complete description of atmospheric chemistry and help others more accurately predict the properties of aerosols, the environmental impact of interfacial oxidation, and the concentrations of tropospheric gases. PMID:26555710

  3. Effects of numerical tolerance levels on an atmospheric chemistry model for mercury

    SciTech Connect

    Ferris, D.C.; Burns, D.S.; Shuford, J.

    1996-12-31

    A Box Model was developed to investigate the atmospheric oxidation processes of mercury in the environment. Previous results indicated the most important influences on the atmospheric concentration of HgO(g) are (i) the flux of HgO(g) volatilization, which is related to the surface medium, extent of contamination, and temperature, and (ii) the presence of Cl{sub 2} in the atmosphere. The numerical solver which has been incorporated into the ORganic CHemistry Integrated Dispersion (ORCHID) model uses the Livermore Solver of Ordinary Differential Equations (LSODE). In the solution of the ODE`s, LSODE uses numerical tolerances. The tolerances effect computer run time, the relative accuracy of ODE calculated species concentrations and whether or not LSODE converges to a solution using this system of equations. The effects of varying these tolerances on the solution of the box model and the ORCHID model will be discussed.

  4. A synthesis of atmospheric mercury depletion event chemistry linking atmosphere, snow and water

    NASA Astrophysics Data System (ADS)

    Steffen, A.; Douglas, T.; Amyot, M.; Ariya, P.; Aspmo, K.; Berg, T.; Bottenheim, J.; Brooks, S.; Cobbett, F.; Dastoor, A.; Dommergue, A.; Ebinghaus, R.; Ferrari, C.; Gardfeldt, K.; Goodsite, M. E.; Lean, D.; Poulain, A.; Scherz, C.; Skov, H.; Sommar, J.; Temme, C.

    2007-07-01

    It was discovered in 1995 that, during the spring time, unexpectedly low concentrations of gaseous elemental mercury (GEM) occurred in the Arctic air. This was surprising for a pollutant known to have a long residence time in the atmosphere; however conditions appeared to exist in the Arctic that promoted this depletion of mercury (Hg). This phenomenon is termed atmospheric mercury depletion events (AMDEs) and its discovery has revolutionized our understanding of the cycling of Hg in Polar Regions while stimulating a significant amount of research to understand its impact to this fragile ecosystem. Shortly after the discovery was made in Canada, AMDEs were confirmed to occur throughout the Arctic, sub-Artic and Antarctic coasts. It is now known that, through a series of photochemically initiated reactions involving halogens, GEM is converted to a more reactive species and is subsequently associated to particles in the air and/or deposited to the polar environment. AMDEs are a means by which Hg is transferred from the atmosphere to the environment that was previously unknown. In this article we review the history of Hg in Polar Regions, the methods used to collect Hg in different environmental media, research results of the current understanding of AMDEs from field, laboratory and modeling work, how Hg cycles around the environment after AMDEs, gaps in our current knowledge and the future impacts that AMDEs may have on polar environments. The research presented has shown that while considerable improvements in methodology to measure Hg have been made the main limitation remains knowing the speciation of Hg in the various media. The processes that drive AMDEs and how they occur are discussed. As well, the roles that the snow pack, oceans, fresh water and the sea ice play in the cycling of Hg are presented. It has been found that deposition of Hg from AMDEs occurs at marine coasts and not far inland and that a fraction of the deposited Hg does not remain in the same

  5. Development of Atmospheric Chemistry Suite (ACS) for ExoMars: Three IR Spectrometers to Characterize the Atmosphere and Climate

    NASA Astrophysics Data System (ADS)

    Korablev, Oleg; Ignatiev, Nikolay; Fedorova, Anna; Trokhimovskiy, Alexander; Montmessin, Franck; Grigoriev, Alexei; Shakun, Alexey

    The Atmospheric Chemistry Suite (ACS) package is being built for the ExoMars Trace Gas Orbiter (TGO). The experiment is dedicated to study the Martian atmosphere, through sensitive measurements of minor species in solar occultations, and the monitoring of the atmospheric state in nadir. The instrument covers the spectral range from near-infrared (0.7 mum) to thermal infrared (17 mum). ACS includes three separate infrared spectrometers. The near-infrared (NIR) channel for the spectral range of 0.7-1.6 mum with resolving power of 20,000 employs the principle of an echelle spectrometer combined with an AOTF (Acousto-Optical Tuneable Filter) for order selection. The main scientific targets of NIR are the measurements of water vapor, aerosols, and dayside or nightside atmospheric emissions. The mid-infrared (MIR) channel is a high-resolution echelle instrument dedicated to solar occultation measurements in the range of 2.2-4.4 mum targeting the resolving power of 50,000. The order separation is done by means of a steerable grating cross-disperser, allowing instantaneous coverage of up to 300-nm range of the spectrum. MIR is dedicated to sensitive measurements of trace gases. The thermal-infrared channel (TIRVIM) is a 2-inch Fourier-transform spectrometer for the spectral range of 1.7-17 mum with resolution from 0.2 to 1.6 cm (-1) . TIRVIM is dedicated to monitoring of atmospheric state in nadir, and will contribute to detection/reducing of upper limits of minor species absorbing beyond 4 mum, complementing MIR. It also targets the mapping of gaseous composition in nadir. The concept of the instrument, its heritage, science objectives, and the status of development will be presented.

  6. On the use of plant emitted volatile organic compounds for atmospheric chemistry simulation experiments

    NASA Astrophysics Data System (ADS)

    Kiendler-Scharr, A.; Hohaus, T.; Yu, Z.; Tillmann, R.; Kuhn, U.; Andres, S.; Kaminski, M.; Wegener, R.; Novelli, A.; Fuchs, H.; Wahner, A.

    2015-12-01

    Biogenic volatile organic compounds (BVOC) contribute to about 90% of the emitted VOC globally with isoprene being one of the most abundant BVOC (Guenther 2002). Intensive efforts in studying and understanding the impact of BVOC on atmospheric chemistry were undertaken in the recent years. However many uncertainties remain, e.g. field studies have shown that in wooded areas measured OH reactivity can often not be explained by measured BVOC and their oxidation products (e.g. Noelscher et al. 2012). This discrepancy may be explained by either a lack of understanding of BVOC sources or insufficient understanding of BVOC oxidation mechanisms. Plants emit a complex VOC mixture containing likely many compounds which have not yet been measured or identified (Goldstein and Galbally 2007). A lack of understanding BVOC sources limits bottom-up estimates of secondary products of BVOC oxidation such as SOA. Similarly, the widespread oversimplification of atmospheric chemistry in simulation experiments, using single compound or simple BVOC mixtures to study atmospheric chemistry processes limit our ability to assess air quality and climate impacts of BVOC. We will present applications of the new extension PLUS (PLant chamber Unit for Simulation) to our atmosphere simulation chamber SAPHIR. PLUS is used to produce representative BVOC mixtures from direct plant emissions. We will report on the performance and characterization of the newly developed chamber. As an exemplary application, trees typical of a Boreal forest environment were used to compare OH reactivity as directly measured by LIF to the OH reactivity calculated from BVOC measured by GC-MS and PTRMS. The comparison was performed for both, primary emissions of trees without any influence of oxidizing agents and using different oxidation schemes. For the monoterpene emitters investigated here, we show that discrepancies between measured and calculated total OH reactivity increase with increasing degree of oxidation

  7. A synthesis of atmospheric mercury depletion event chemistry in the atmosphere and snow

    NASA Astrophysics Data System (ADS)

    Steffen, A.; Douglas, T.; Amyot, M.; Ariya, P.; Aspmo, K.; Berg, T.; Bottenheim, J.; Brooks, S.; Cobbett, F.; Dastoor, A.; Dommergue, A.; Ebinghaus, R.; Ferrari, C.; Gardfeldt, K.; Goodsite, M. E.; Lean, D.; Poulain, A. J.; Scherz, C.; Skov, H.; Sommar, J.; Temme, C.

    2008-03-01

    It was discovered in 1995 that, during the spring time, unexpectedly low concentrations of gaseous elemental mercury (GEM) occurred in the Arctic air. This was surprising for a pollutant known to have a long residence time in the atmosphere; however conditions appeared to exist in the Arctic that promoted this depletion of mercury (Hg). This phenomenon is termed atmospheric mercury depletion events (AMDEs) and its discovery has revolutionized our understanding of the cycling of Hg in Polar Regions while stimulating a significant amount of research to understand its impact to this fragile ecosystem. Shortly after the discovery was made in Canada, AMDEs were confirmed to occur throughout the Arctic, sub-Artic and Antarctic coasts. It is now known that, through a series of photochemically initiated reactions involving halogens, GEM is converted to a more reactive species and is subsequently associated to particles in the air and/or deposited to the polar environment. AMDEs are a means by which Hg is transferred from the atmosphere to the environment that was previously unknown. In this article we review Hg research taken place in Polar Regions pertaining to AMDEs, the methods used to collect Hg in different environmental media, research results of the current understanding of AMDEs from field, laboratory and modeling work, how Hg cycles around the environment after AMDEs, gaps in our current knowledge and the future impacts that AMDEs may have on polar environments. The research presented has shown that while considerable improvements in methodology to measure Hg have been made but the main limitation remains knowing the speciation of Hg in the various media. The processes that drive AMDEs and how they occur are discussed. As well, the role that the snow pack and the sea ice play in the cycling of Hg is presented. It has been found that deposition of Hg from AMDEs occurs at marine coasts and not far inland and that a fraction of the deposited Hg does not remain in the

  8. Carbon dioxide in the atmosphere. [and other research projects

    NASA Technical Reports Server (NTRS)

    Johnson, F. S.

    1974-01-01

    Research projects for the period ending September 15, 1973 are reported as follows: (1) the abundances of carbon dioxide in the atmosphere, and the processes by which it is released from carbonate deposits in the earth and then transferred to organic material by photosynthesis; the pathways for movement of carbon and oxygen through the atmosphere; (2) space science computation assistance by PDP computer; the performance characteristics and user instances; (3) OGO-6 data analysis studies of the variations of nighttime ion temperature in the upper atmosphere.

  9. Seasonal Atmospheric Chemistry at Summit, Greenland Based on N and O Isotopes of Nitrate

    NASA Astrophysics Data System (ADS)

    Hastings, M. G.; Steig, E. J.; Sigman, D. M.; Jarvis, J.

    2003-12-01

    Nitric acid (HNO3), or nitrate (NO3-) is the major sink for reactive nitrogen oxides (NOx) in the atmosphere. Ice core records of NO3- could provide information about past reactive nitrogen chemistry and oxidative capacity of the atmosphere. However, processes that take place in the surface snow (e.g., evaporation, photolysis) can affect the final NO3- concentrations that are archived in the ice cores, making it difficult to interpret past changes in atmospheric chemistry or climate. The isotopic composition of NO3- in surface snow provides an additional constraint on the effect of post-depositional processing in the upper meter of snowpack on the NO3- content measured in glacial ice cores. Furthermore, the isotopes of NO3- in ice cores have the potential to allow for reconstruction of sources of NOx and aspects of atmospheric chemistry in the past. Snow pit samples (sampled every 3 cm to 1 m) collected at Summit, Greenland during August 2001 show seasonal variation in N and O isotopes of NO3-. δ 15N of NO3- in the upper meter of snow ranges from -15 to +16 per mil (vs. atmospheric N2), with higher values found in summertime snow. The δ 15N of snowpack NO3- falls in the range reported for NO3- in precipitation from other parts of the world. δ 18O of NO3- in the snowpack ranges from 65 to 80 per mil (vs. VSMOW), similar to high values observed for rainwater and aerosol NO3-. In contrast to the δ 15N, the δ 18O of NO3- is lower in summertime snow than in wintertime. Preliminary analyses also show diurnal variation in the isotopes of NO3- during summer, with depletion of 15N and 18O at "night" followed by enrichment during the "day." The similar behavior of the N and O isotopes is suggestive of a simple physical mechanism for the diurnal change, such as photolysis or evaporation. The seasonal δ 15N and δ 18O, however, vary in opposite directions suggesting that these processes are not the dominant mechanism determining the seasonal signals. Our hypothesis is

  10. Study of the atmospheric chemistry of radon progeny in laboratory and real indoor atmospheres

    SciTech Connect

    Hopke, P.K.

    1992-07-01

    This report covers the second year of the 28 month grant current grant to Clarkson University to study the chemical and physical behavior of the polonium 218 atom immediately following its formation by the alpha decay of radon. Because small changes in size for activity result in large changes in the delivered dose per unit exposure, this behavior must be understood if the exposure to radon progeny and it dose to the cells in the respiratory tract are to be fully assessed. Two areas of radon progeny behavior are being pursued; laboratory studies under controlled conditions to better understand the fundamental physical and chemical process that affect the progeny's atmospheric behavior and studies in actual indoor environments to develop a better assessment of the exposure of the occupants of that space to the size and concentration of the indoor radioactive aerosol. This report describes the progress toward achieving these objectives.

  11. Energetic electron precipitation impacts on the middle atmosphere: From satellite observations to chemistry-climate modeling

    NASA Astrophysics Data System (ADS)

    Sinnhuber, Miriam; Bender, Stefan; Burrows, John P.; Funke, Bernd; Fytterer, Tilo; Nieder, Holger; Reddmann, Thomas; Stiller, Gabriele; Versick, Stefan; von Clarmann, Thomas; Maik Wissing, Jan

    2016-04-01

    Precipitation of energetic particles - mainly protons from solar coronal mass ejections or electrons accelerated in auroral or geomagnetic storms - directly affects the mesosphere and lower thermosphere. Nitric oxides (N, NO, NO2) and hydrogen radicals (H, OH) are formed by particle impact dissociation and ionization and subsequent ion chemistry reactions. However, the stratosphere and possibly even tropospheric weather systems can be affected indirectly by downward transport of particle-induced nitric oxides from their source regions into the stratosphere during polar winter, subsequent ozone depletion, and dynamical feedbacks with radiative (ozone) heating and cooling. This so-called "EPP indirect effect" forms one aspect of solar-climate interactions which will be recommended to include in chemistry-climate models, e.g., in the upcoming CMIP-6 experiment. We will present recent observations of mesospheric nitric oxide formation due to particle precipitation, as well as downwelling of particle induced NOy. Observations are compared to results from three 3-dimensional global chemistry-climate and chemistry-transport models of the middle atmosphere, and the subsequent ozone depletion is assessed using CCM / CTM model results.

  12. Oxidation of a new Biogenic VOC: Chamber Studies of the Atmospheric Chemistry of Methyl Chavicol

    NASA Astrophysics Data System (ADS)

    Bloss, William; Alam, Mohammed; Adbul Raheem, Modinah; Rickard, Andrew; Hamilton, Jacqui; Pereira, Kelly; Camredon, Marie; Munoz, Amalia; Vazquez, Monica; Vera, Teresa; Rodenas, Mila

    2013-04-01

    The oxidation of volatile organic compounds (VOCs) leads to formation of ozone and SOA, with consequences for air quality, health, crop yields, atmospheric chemistry and radiative transfer. Recent observations have identified Methyl Chavicol ("MC": Estragole; 1-allyl-4-methoxybenzene, C10H12O) as a major BVOC above pine forests in the USA, and oil palm plantations in Malaysian Borneo. Palm oil cultivation, and hence MC emissions, may be expected to increase with societal food and bio fuel demand. We present the results of a series of simulation chamber experiments to assess the atmospheric fate of MC. Experiments were performed in the EUPHORE facility, monitoring stable product species, radical intermediates, and aerosol production and composition. We determine rate constants for reaction of MC with OH and O3, and ozonolysis radical yields. Stable product measurements (FTIR, PTRMS, GC-SPME) are used to determine the yields of stable products formed from OH- and O3- initiated oxidation, and to develop an understanding of the initial stages of the MC degradation chemistry. A surrogate mechanism approach is used to simulate MC degradation within the MCM, evaluated in terms of ozone production measured in the chamber experiments, and applied to quantify the role of MC in the real atmosphere.

  13. CAM-chem: description and evaluation of interactive atmospheric chemistry in the Community Earth System Model

    SciTech Connect

    Lamarque, J.-F.; Emmons, L.; Hess, Peter; Kinnison, Douglas E.; Tilmes, S.; Vitt, Francis; Heald, C. L.; Holland, Elisabeth A.; Lauritzen, P. H.; Neu, J.; Orlando, J. J.; Rasch, Philip J.; Tyndall, G. S.

    2012-03-27

    We discuss and evaluate the representation of atmospheric chemistry in the global Community Atmosphere Model (CAM) version 4, the atmospheric component of the Community Earth System Model (CESM). We present a variety of configurations for the representation of tropospheric and stratospheric chemistry, wet removal, and online and offline meteorology. Results from simulations illustrating these configurations are compared with surface, aircraft and satellite observations. Major biases include a negative bias in the high-latitude CO distribution, a positive bias in upper-tropospheric/lower-stratospheric ozone, and a positive bias in summertime surface ozone (over the United States and Europe). The tropospheric net chemical ozone production varies significantly between configurations, partly related to variations in stratosphere-troposphere exchange. Aerosol optical depth tends to be underestimated over most regions, while comparison with aerosol surface measurements over the United States indicate reasonable results for sulfate, especially in the online simulation. Other aerosol species exhibit significant biases. Overall, the model-data comparison indicates that the offline simulation driven by GEOS5 meteorological analyses provides the best simulation, possibly due in part to the increased vertical resolution (52 levels instead of 26 for online dynamics). The CAM-chem code as described in this paper, along with all the necessary datasets needed to perform the simulations described here, are available for download at www.cesm.ucar.edu.

  14. A numerical method for parameterization of atmospheric chemistry - Computation of tropospheric OH

    NASA Technical Reports Server (NTRS)

    Spivakovsky, C. M.; Wofsy, S. C.; Prather, M. J.

    1990-01-01

    An efficient and stable computational scheme for parameterization of atmospheric chemistry is described. The 24-hour-average concentration of OH is represented as a set of high-order polynomials in variables such as temperature, densities of H2O, CO, O3, and NO(t) (defined as NO + NO2 + NO3 + 2N2O5 + HNO2 + HNO4) as well as variables determining solar irradiance: cloud cover, density of the overhead ozone column, surface albedo, latitude, and solar declination. This parameterization of OH chemistry was used in the three-dimensional study of global distribution of CH3CCl3. The proposed computational scheme can be used for parameterization of rates of chemical production and loss or of any other output of a full chemical model.

  15. Untangling the Chemical Evolution of Titan's Atmosphere and Surface -- From Homogeneous to Heterogeneous Chemistry

    SciTech Connect

    Kaiser, Ralf I.; Maksyutenko, Pavlo; Ennis, Courtney; Zhang, Fangtong; Gu, Xibin; Krishtal, Sergey P.; Mebel, Alexander M.; Kostko, Oleg; Ahmed, Musahid

    2010-03-16

    The arrival of the Cassini-Huygens probe at Saturn's moon Titan - the only Solar System body besides Earth and Venus with a solid surface and a thick atmosphere with a pressure of 1.4 atm at surface level - in 2004 opened up a new chapter in the history of Solar System exploration. The mission revealed Titan as a world with striking Earth-like landscapes involving hydrocarbon lakes and seas as well as sand dunes and lava-like features interspersed with craters and icy mountains of hitherto unknown chemical composition. The discovery of a dynamic atmosphere and active weather system illustrates further the similarities between Titan and Earth. The aerosol-based haze layers, which give Titan its orange-brownish color, are not only Titan's most prominent optically visible features, but also play a crucial role in determining Titan's thermal structure and chemistry. These smog-like haze layers are thought to be very similar to those that were present in Earth's atmosphere before life developed more than 3.8 billion years ago, absorbing the destructive ultraviolet radiation from the Sun, thus acting as 'prebiotic ozone' to preserve astrobiologically important molecules on Titan. Compared to Earth, Titan's low surface temperature of 94 K and the absence of liquid water preclude the evolution of biological chemistry as we know it. Exactly because of these low temperatures, Titan provides us with a unique prebiotic 'atmospheric laboratory' yielding vital clues - at the frozen stage - on the likely chemical composition of the atmosphere of the primitive Earth. However, the underlying chemical processes, which initiate the haze formation from simple molecules, have been not understood well to date.

  16. Addition of a Project-Based Component to a Conventional Expository Physical Chemistry Laboratory

    ERIC Educational Resources Information Center

    Tsaparlis, Georgios; Gorezi, Marianna

    2007-01-01

    Students should enjoy their laboratory classes and for this purpose a project-based activity is added to a conventional physical chemistry laboratory. Students were given project work instead of conventional experiment and then they had to make progress in the project according to instructions and then carry out experiments related to the project.

  17. The NOx dependence of bromine chemistry in the Arctic atmospheric boundary layer

    NASA Astrophysics Data System (ADS)

    Custard, K. D.; Thompson, C. R.; Pratt, K. A.; Shepson, P. B.; Liao, J.; Huey, L. G.; Orlando, J. J.; Weinheimer, A. J.; Apel, E.; Hall, S. R.; Flocke, F.; Mauldin, L.; Hornbrook, R. S.; Pöhler, D.; S., General; Zielcke, J.; Simpson, W. R.; Platt, U.; Fried, A.; Weibring, P.; Sive, B. C.; Ullmann, K.; Cantrell, C.; Knapp, D. J.; Montzka, D. D.

    2015-09-01

    Arctic boundary layer nitrogen oxides (NOx = NO2 + NO) are naturally produced in and released from the sunlit snowpack and range between 10 to 100 pptv in the remote background surface layer air. These nitrogen oxides have significant effects on the partitioning and cycling of reactive radicals such as halogens and HOx (OH + HO2). However, little is known about the impacts of local anthropogenic NOx emission sources on gas-phase halogen chemistry in the Arctic, and this is important because these emissions can induce large variability in ambient NOx and thus local chemistry. In this study, a zero-dimensional photochemical kinetics model was used to investigate the influence of NOx on the unique springtime halogen and HOx chemistry in the Arctic. Trace gas measurements obtained during the 2009 OASIS (Ocean - Atmosphere - Sea Ice - Snowpack) field campaign at Barrow, AK were used to constrain many model inputs. We find that elevated NOx significantly impedes gas-phase halogen radical-based depletion of ozone, through the production of a variety of reservoir species, including HNO3, HO2NO2, peroxyacetyl nitrate (PAN), BrNO2, ClNO2 and reductions in BrO and HOBr. The effective removal of BrO by anthropogenic NOx was directly observed from measurements conducted near Prudhoe Bay, AK during the 2012 Bromine, Ozone, and Mercury Experiment (BROMEX). Thus, while changes in snow-covered sea ice attributable to climate change may alter the availability of molecular halogens for ozone and Hg depletion, predicting the impact of climate change on polar atmospheric chemistry is complex and must take into account the simultaneous impact of changes in the distribution and intensity of anthropogenic combustion sources. This is especially true for the Arctic, where NOx emissions are expected to increase because of increasing oil and gas extraction and shipping activities.

  18. 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.

  19. Prebiotic chemistry and atmospheric warming of early Earth by an active young Sun

    NASA Astrophysics Data System (ADS)

    Airapetian, V. S.; Glocer, A.; Gronoff, G.; Hébrard, E.; Danchi, W.

    2016-06-01

    Nitrogen is a critical ingredient of complex biological molecules. Molecular nitrogen, however, which was outgassed into the Earth’s early atmosphere, is relatively chemically inert and nitrogen fixation into more chemically reactive compounds requires high temperatures. Possible mechanisms of nitrogen fixation include lightning, atmospheric shock heating by meteorites, and solar ultraviolet radiation. Here we show that nitrogen fixation in the early terrestrial atmosphere can be explained by frequent and powerful coronal mass ejection events from the young Sun--so-called superflares. Using magnetohydrodynamic simulations constrained by Kepler Space Telescope observations, we find that successive superflare ejections produce shocks that accelerate energetic particles, which would have compressed the early Earth’s magnetosphere. The resulting extended polar cap openings provide pathways for energetic particles to penetrate into the atmosphere and, according to our atmospheric chemistry simulations, initiate reactions converting molecular nitrogen, carbon dioxide and methane to the potent greenhouse gas nitrous oxide as well as hydrogen cyanide, an essential compound for life. Furthermore, the destruction of N2, CO2 and CH4 suggests that these greenhouse gases cannot explain the stability of liquid water on the early Earth. Instead, we propose that the efficient formation of nitrous oxide could explain a warm early Earth.

  20. A Collaborative, Wiki-Based Organic Chemistry Project Incorporating Free Chemistry Software on the Web

    ERIC Educational Resources Information Center

    Evans, Michael J.; Moore, Jeffrey S.

    2011-01-01

    In recent years, postsecondary instructors have recognized the potential of wikis to transform the way students learn in a collaborative environment. However, few instructors have embraced in-depth student use of chemistry software for the creation of interactive chemistry content on the Web. Using currently available software, students are able…

  1. Management of the Atmosphere Resource Recovery and Environmental Monitoring Project

    NASA Technical Reports Server (NTRS)

    Roman, Monsi; Perry, Jay; Howard, David

    2013-01-01

    The Advanced Exploration Systems Program's Atmosphere Resource Recovery and Environmental Monitoring (ARREM) project is working to further optimize atmosphere revitalization and environmental monitoring system architectures. This paper discusses project management strategies that tap into skill sets across multiple engineering disciplines, projects, field centers, and industry to achieve the project success. It is the project's objective to contribute to system advances that will enable sustained exploration missions beyond Lower Earth Orbit (LEO) and improve affordability by focusing on the primary goals of achieving high reliability, improving efficiency, and reducing dependence on ground-based logistics resupply. Technology demonstrations are achieved by infusing new technologies and concepts with existing developmental hardware and operating in a controlled environment simulating various crewed habitat scenarios. The ARREM project's strengths include access to a vast array of existing developmental hardware that perform all the vital atmosphere revitalization functions, exceptional test facilities to fully evaluate system performance, and a well-coordinated partnering effort among the NASA field centers and industry partners to provide the innovative expertise necessary to succeed.

  2. Final Report for LDRD Project 05-ERD-050: "Developing a Reactive Chemistry Capability for the NARAC Operational Model (LODI)"

    SciTech Connect

    Cameron-Smith, P; Grant, K; Connell, P

    2008-02-11

    In support of the National Security efforts of LLNL, this project addressed the existing imbalance between dispersion and chemical capabilities of LODI (Lagrangian Operational Dispersion Integrator--the NARAC operational dispersion model). We have demonstrated potentially large effects of atmospheric chemistry on the impact of chemical releases (e.g., industrial chemicals and nerve agents). Prior to our work, LODI could only handle chains of first-order losses (exponential decays) that were independent of time and space, limiting NARAC's capability to respond when reactive chemistry is important. We significantly upgraded the chemistry and aerosol capability of LODI to handle (1) arbitrary networks of chemical reactions, (2) mixing and reactions with ambient species, (3) evaporation and condensation of aerosols, and (4) heat liberated from chemical reactions and aerosol condensation (which can cause a cold and dense plume hugging the ground to rise into the atmosphere, then descend to the ground again as droplets). When this is made operational, it will significantly improve NARAC's ability to respond to terrorist attacks and industrial accidents that involve reactive chemistry, including many chemical agents and toxic industrial chemicals (TICS). As a dual-use, the resulting model also has the potential to be a state-of-the-art air-quality model. Chemical releases are the most common type of airborne hazardous release and many operational applications involve such scenarios. The new capability we developed is therefore relevant to the needs of the Department of Energy (DOE), Department of Homeland Security (DHS) and Department of Defense (DoD).

  3. Lessons Learned from the Bay Region Atmospheric Chemistry Experiment (BRACE) and Implications for Nitrogen Management of Tampa Bay

    EPA Science Inventory

    Results from air quality modeling and field measurements made as part of the Bay Region Atmospheric Chemistry Experiment (BRACE) along with related scientific literature were reviewed to provide an improved estimate of atmospheric reactive nitrogen (N) deposition to Tampa Bay, to...

  4. A new Geoengineering Model Intercomparison Project (GeoMIP) experiment designed for climate and chemistry models

    NASA Astrophysics Data System (ADS)

    Tilmes, S.; Mills, M. J.; Niemeier, U.; Schmidt, H.; Robock, A.; Kravitz, B.; Lamarque, J.-F.; Pitari, G.; English, J. M.

    2015-01-01

    A new Geoengineering Model Intercomparison Project (GeoMIP) experiment "G4 specified stratospheric aerosols" (short name: G4SSA) is proposed to investigate the impact of stratospheric aerosol geoengineering on atmosphere, chemistry, dynamics, climate, and the environment. In contrast to the earlier G4 GeoMIP experiment, which requires an emission of sulfur dioxide (SO2) into the model, a prescribed aerosol forcing file is provided to the community, to be consistently applied to future model experiments between 2020 and 2100. This stratospheric aerosol distribution, with a total burden of about 2 Tg S has been derived using the ECHAM5-HAM microphysical model, based on a continuous annual tropical emission of 8 Tg SO2 yr-1. A ramp-up of geoengineering in 2020 and a ramp-down in 2070 over a period of 2 years are included in the distribution, while a background aerosol burden should be used for the last 3 decades of the experiment. The performance of this experiment using climate and chemistry models in a multi-model comparison framework will allow us to better understand the impact of geoengineering and its abrupt termination after 50 years in a changing environment. The zonal and monthly mean stratospheric aerosol input data set is available at https://www2.acd.ucar.edu/gcm/geomip-g4-specified-stratospheric-aerosol-data-set.

  5. A new Geoengineering Model Intercomparison Project (GeoMIP) experiment designed for climate and chemistry models

    DOE PAGESBeta

    Tilmes, S.; Mills, Mike; Niemeier, Ulrike; Schmidt, Hauke; Robock, Alan; Kravitz, Benjamin S.; Lamarque, J. F.; Pitari, G.; English, J. M.

    2015-01-15

    A new Geoengineering Model Intercomparison Project (GeoMIP) experiment "G4 specified stratospheric aerosols" (short name: G4SSA) is proposed to investigate the impact of stratospheric aerosol geoengineering on atmosphere, chemistry, dynamics, climate, and the environment. In contrast to the earlier G4 GeoMIP experiment, which requires an emission of sulfur dioxide (SO₂) into the model, a prescribed aerosol forcing file is provided to the community, to be consistently applied to future model experiments between 2020 and 2100. This stratospheric aerosol distribution, with a total burden of about 2 Tg S has been derived using the ECHAM5-HAM microphysical model, based on a continuous annualmore » tropical emission of 8 Tg SO₂ yr⁻¹. A ramp-up of geoengineering in 2020 and a ramp-down in 2070 over a period of 2 years are included in the distribution, while a background aerosol burden should be used for the last 3 decades of the experiment. The performance of this experiment using climate and chemistry models in a multi-model comparison framework will allow us to better understand the impact of geoengineering and its abrupt termination after 50 years in a changing environment. The zonal and monthly mean stratospheric aerosol input data set is available at https://www2.acd.ucar.edu/gcm/geomip-g4-specified-stratospheric-aerosol-data-set.« less

  6. A new Geoengineering Model Intercomparison Project (GeoMIP) experiment designed for climate and chemistry models

    SciTech Connect

    Tilmes, S.; Mills, Mike; Niemeier, Ulrike; Schmidt, Hauke; Robock, Alan; Kravitz, Benjamin S.; Lamarque, J. F.; Pitari, G.; English, J. M.

    2015-01-15

    A new Geoengineering Model Intercomparison Project (GeoMIP) experiment "G4 specified stratospheric aerosols" (short name: G4SSA) is proposed to investigate the impact of stratospheric aerosol geoengineering on atmosphere, chemistry, dynamics, climate, and the environment. In contrast to the earlier G4 GeoMIP experiment, which requires an emission of sulfur dioxide (SO₂) into the model, a prescribed aerosol forcing file is provided to the community, to be consistently applied to future model experiments between 2020 and 2100. This stratospheric aerosol distribution, with a total burden of about 2 Tg S has been derived using the ECHAM5-HAM microphysical model, based on a continuous annual tropical emission of 8 Tg SO₂ yr⁻¹. A ramp-up of geoengineering in 2020 and a ramp-down in 2070 over a period of 2 years are included in the distribution, while a background aerosol burden should be used for the last 3 decades of the experiment. The performance of this experiment using climate and chemistry models in a multi-model comparison framework will allow us to better understand the impact of geoengineering and its abrupt termination after 50 years in a changing environment. The zonal and monthly mean stratospheric aerosol input data set is available at https://www2.acd.ucar.edu/gcm/geomip-g4-specified-stratospheric-aerosol-data-set.

  7. The Skylab concentrated atmospheric radiation project. [Arizona and New Mexico

    NASA Technical Reports Server (NTRS)

    Kuhn, P. M.; Whitehead, V. S.; Marlatt, W. E.

    1975-01-01

    The Skylab field phase in June, August and September of 1973 for the Skylab concentrated atmospheric radiation project provided an opportunity to conduct infrared and solar observations and subsequent calculations beneath the orbiting space vehicle during EREP overpasses. Infrared and solar transmission and absorption properties observed within the atmosphere were compared with EREP experiments, notably the S-191 and S-192. These same observations were later employed in the development and comparison of various atmospheric infrared and solar radiative transfer approximations. Solar radiation observations and calculations in the scattering atmosphere included the 0.4 to 1.1 microns spectral range while infrared observations and calculations covered the spectral band and portions thereof within the 5.0 to 40.0 microns region. Principal conclusions drawn from the solar radiation research and the infrared radiation research are discussed.

  8. On the relationship between total ozone and atmospheric dynamics and chemistry at mid-latitudes - Part 1: Statistical models and spatial fingerprints of atmospheric dynamics and chemistry

    NASA Astrophysics Data System (ADS)

    Frossard, L.; Rieder, H. E.; Ribatet, M.; Staehelin, J.; Maeder, J. A.; Di Rocco, S.; Davison, A. C.; Peter, T.

    2013-01-01

    We use statistical models for mean and extreme values of total column ozone to analyze "fingerprints" of atmospheric dynamics and chemistry on long-term ozone changes at northern and southern mid-latitudes on grid cell basis. At each grid cell, the r-largest order statistics method is used for the analysis of extreme events in low and high total ozone (termed ELOs and EHOs, respectively), and an autoregressive moving average (ARMA) model is used for the corresponding mean value analysis. In order to describe the dynamical and chemical state of the atmosphere, the statistical models include important atmospheric covariates: the solar cycle, the Quasi-Biennial Oscillation (QBO), ozone depleting substances (ODS) in terms of equivalent effective stratospheric chlorine (EESC), the North Atlantic Oscillation (NAO), the Antarctic Oscillation (AAO), the El Niño/Southern Oscillation (ENSO), and aerosol load after the volcanic eruptions of El Chichón and Mt. Pinatubo. The influence of the individual covariates on mean and extreme levels in total column ozone is derived on a grid cell basis. The results show that "fingerprints", i.e., significant influence, of dynamical and chemical features are captured in both the "bulk" and the tails of the statistical distribution of ozone, respectively described by mean values and EHOs/ELOs. While results for the solar cycle, QBO, and EESC are in good agreement with findings of earlier studies, unprecedented spatial fingerprints are retrieved for the dynamical covariates. Column ozone is enhanced over Labrador/Greenland, the North Atlantic sector and over the Norwegian Sea, but is reduced over Europe, Russia and the Eastern United States during the positive NAO phase, and vice-versa during the negative phase. The NAO's southern counterpart, the AAO, strongly influences column ozone at lower southern mid-latitudes, including the southern parts of South America and the Antarctic Peninsula, and the central southern mid-latitudes. Results

  9. Studies in photochemical smog chemistry. I. Atmospheric chemistry of toluene. II. Analysis of chemical reaction mechanisms for photochemical smog

    SciTech Connect

    Leone, J.A.

    1985-01-01

    This study focuses on two related topics in the gas phase organic chemistry of importance in urban air pollution. Part I describes an experimental and modeling effort aimed at developing a new explicit reaction mechanism for the atmospheric photooxidation of toluene. This mechanism is tested using experimental data from both indoor and outdoor smog chamber facilities. The predictions of the new reaction mechanism are found to be in good agreement with both sets of experimental data. Additional simulations performed with the new mechanism are used to investigate various mechanistic paths, and to gain insight into areas where the understanding is not complete. The outdoor experimental facility, which was built to provide the second set of experimental data, consists of a 65 cubic meter teflon smog chamber together with full instrumentation capable of measuring ozone, nitrogen dioxide, nitric oxide, peroxyacetyl nitrate (PAN), carbon monoxide, relative humidity, temperature, aerosol size distributions, and of course toluene and its photooxidation products. In Part II, a theoretical analysis of lumped chemical reaction mechanisms for photochemical smog is presented. Included is a description of a new counter species analysis technique which can be used to analyze any complex chemical reaction mechanism. Finally, a new lumped mechanism for photochemical smog is developed and tested against experimental data from two smog chamber facilities. Advantages of this mechanism relative to the existing lumped mechanisms are discussed.

  10. Non-OH chemistry in oxidation flow reactors for the study of atmospheric chemistry systematically examined by modeling

    DOE PAGESBeta

    Peng, Zhe; Day, Douglas A.; Ortega, Amber M.; Palm, Brett B.; Hu, Weiwei; Stark, Harald; Li, Rui; Tsigaridis, Kostas; Brune, William H.; Jimenez, Jose L.

    2016-04-06

    Oxidation flow reactors (OFRs) using low-pressure Hg lamp emission at 185 and 254 nm produce OH radicals efficiently and are widely used in atmospheric chemistry and other fields. However, knowledge of detailed OFR chemistry is limited, allowing speculation in the literature about whether some non-OH reactants, including several not relevant for tropospheric chemistry, may play an important role in these OFRs. These non-OH reactants are UV radiation, O(1D), O(3P), and O3. In this study, we investigate the relative importance of other reactants to OH for the fate of reactant species in OFR under a wide range of conditions via box modeling.more » The relative importance of non-OH species is less sensitive to UV light intensity than to water vapor mixing ratio (H2O) and external OH reactivity (OHRext), as both non-OH reactants and OH scale roughly proportionally to UV intensity. We show that for field studies in forested regions and also the urban area of Los Angeles, reactants of atmospheric interest are predominantly consumed by OH. We find that O(1D), O(3P), and O3 have relative contributions to volatile organic compound (VOC) consumption that are similar or lower than in the troposphere. The impact of O atoms can be neglected under most conditions in both OFR and troposphere. We define “riskier OFR conditions” as those with either low H2O (< 0.1 %) or high OHRext ( ≥  100 s−1 in OFR185 and > 200 s−1 in OFR254). We strongly suggest avoiding such conditions as the importance of non-OH reactants can be substantial for the most sensitive species, although OH may still dominate under some riskier conditions, depending on the species present. Photolysis at non-tropospheric wavelengths (185 and 254 nm) may play a significant (> 20 %) role in the degradation of some aromatics, as well as some oxidation intermediates, under riskier reactor conditions, if the quantum yields are high. Under riskier conditions, some biogenics can have

  11. Non-OH chemistry in oxidation flow reactors for the study of atmospheric chemistry systematically examined by modeling

    DOE PAGESBeta

    Peng, Zhe; Day, Douglas A.; Ortega, Amber M.; Palm, Brett B.; Hu, Weiwei; Stark, Harald; Li, Rui; Tsigaridis, Kostas; Brune, William H.; Jimenez, Jose L.

    2016-04-06

    Oxidation flow reactors (OFRs) using low-pressure Hg lamp emission at 185 and 254 nm produce OH radicals efficiently and are widely used in atmospheric chemistry and other fields. However, knowledge of detailed OFR chemistry is limited, allowing speculation in the literature about whether some non-OH reactants, including several not relevant for tropospheric chemistry, may play an important role in these OFRs. These non-OH reactants are UV radiation, O(1D), O(3P), and O3. In this study, we investigate the relative importance of other reactants to OH for the fate of reactant species in OFR under a wide range of conditions via box modeling.more » The relative importance of non-OH species is less sensitive to UV light intensity than to water vapor mixing ratio (H2O) and external OH reactivity (OHRext), as both non-OH reactants and OH scale roughly proportionally to UV intensity. We show that for field studies in forested regions and also the urban area of Los Angeles, reactants of atmospheric interest are predominantly consumed by OH. We find that O(1D), O(3P), and O3 have relative contributions to volatile organic compound (VOC) consumption that are similar or lower than in the troposphere. The impact of O atoms can be neglected under most conditions in both OFR and troposphere. We define “riskier OFR conditions” as those with either low H2O (< 0.1%) or high OHRext (≥ 100s–1 in OFR185 and > 200s–1 in OFR254). We strongly suggest avoiding such conditions as the importance of non-OH reactants can be substantial for the most sensitive species, although OH may still dominate under some riskier conditions, depending on the species present. Photolysis at non-tropospheric wavelengths (185 and 254 nm) may play a significant (> 20%) role in the degradation of some aromatics, as well as some oxidation intermediates, under riskier reactor conditions, if the quantum yields are high. Under riskier conditions, some biogenics can have substantial destructions by O3

  12. Non-OH chemistry in oxidation flow reactors for the study of atmospheric chemistry systematically examined by modeling

    NASA Astrophysics Data System (ADS)

    Peng, Zhe; Day, Douglas A.; Ortega, Amber M.; Palm, Brett B.; Hu, Weiwei; Stark, Harald; Li, Rui; Tsigaridis, Kostas; Brune, William H.; Jimenez, Jose L.

    2016-04-01

    Oxidation flow reactors (OFRs) using low-pressure Hg lamp emission at 185 and 254 nm produce OH radicals efficiently and are widely used in atmospheric chemistry and other fields. However, knowledge of detailed OFR chemistry is limited, allowing speculation in the literature about whether some non-OH reactants, including several not relevant for tropospheric chemistry, may play an important role in these OFRs. These non-OH reactants are UV radiation, O(1D), O(3P), and O3. In this study, we investigate the relative importance of other reactants to OH for the fate of reactant species in OFR under a wide range of conditions via box modeling. The relative importance of non-OH species is less sensitive to UV light intensity than to water vapor mixing ratio (H2O) and external OH reactivity (OHRext), as both non-OH reactants and OH scale roughly proportionally to UV intensity. We show that for field studies in forested regions and also the urban area of Los Angeles, reactants of atmospheric interest are predominantly consumed by OH. We find that O(1D), O(3P), and O3 have relative contributions to volatile organic compound (VOC) consumption that are similar or lower than in the troposphere. The impact of O atoms can be neglected under most conditions in both OFR and troposphere. We define "riskier OFR conditions" as those with either low H2O (< 0.1 %) or high OHRext ( ≥ 100 s-1 in OFR185 and > 200 s-1 in OFR254). We strongly suggest avoiding such conditions as the importance of non-OH reactants can be substantial for the most sensitive species, although OH may still dominate under some riskier conditions, depending on the species present. Photolysis at non-tropospheric wavelengths (185 and 254 nm) may play a significant (> 20 %) role in the degradation of some aromatics, as well as some oxidation intermediates, under riskier reactor conditions, if the quantum yields are high. Under riskier conditions, some biogenics can have substantial destructions by O3, similarly to

  13. 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.

  14. Diphosphine is an intermediate in the photolysis of phosphine to phosphorus and hydrogen. [Jupiter atmospheric chemistry

    NASA Technical Reports Server (NTRS)

    Ferris, J. P.; Benson, R.

    1980-01-01

    The photolysis of phosphine to red phosphorus (P4) and hydrogen is investigated in light of the potential significance of the reaction in the atmospheric chemistry of Jupiter. It is reported that the photolysis of PH3 at room temperature by a 206.2-nm light source gave rise to a product identified by its UV and IR spectra and gas chromatographic retention time as P2H4, the yield of which is found to increase to a maximum and then decrease to 20% of the maximum value with illumination time. A mechanism for phosphine photolysis including diphosphine formation as an intermediate step is proposed, and it is concluded that P2H4 is a likely constituent of the atmospheres of the Jovian planets.

  15. Development and application of the High resolution VOC Atmospheric Chemistry in Canopies (Hi-VACC) model

    NASA Astrophysics Data System (ADS)

    Kenny, W.; Bohrer, G.; Chatziefstratiou, E.

    2013-12-01

    We have been working to develop a new post-processing model - High resolution VOC Atmospheric Chemistry in Canopies (Hi-VACC) - which will be able to resolve the dispersion and chemistry of reacting chemical species given their emission rates from the vegetation and soil, driven by high resolution meteorological forcing and wind fields from various high resolution atmospheric regional and large-eddy simulations. Hi-VACC reads in fields of pressure, temperature, humidity, air density, short-wave radiation, wind (3-D u, v and w components) and sub-grid-scale turbulence that were simulated by a high resolution atmospheric model. This meteorological forcing data is provided as snapshots of 3-D fields. Presently, the advection-diffusion portion of the model is fully developed, and we have tested it using a number of RAMS-based Forest Large Eddy Simulation (RAFLES) runs. Here, we present results from utilizing Hi-VACC in a few different contexts where it performs smoke and particle dispersion well. These include simulations of smoke dispersion from a theoretical forest fire in a domain in The Pine Barrens in New Jersey, as well as simulations to test the effects of heat flux on a scalar plume dispersing over a vegetative windbreak in an agricultural setting. Additional, we show initial results from testing the coupled chemistry component of Hi-VACC. One of the primary benefits of Hi-VACC is that users of other models can utilize this tool with only minimal work on their part -- processing their output fields into the appropriate HI-VACC input format. We have developed our model such that for whatever atmospheric model is being used with it, a MATLAB function must be written to extract the necessary information from the output files of that model and shape it into the proper format. This is the only model-specific work required. As such, this sort of smoke dispersion modeling performed by Hi-VACC - as well as its other capabilities - can be easily performed in other

  16. Elevated atmospheric carbon dioxide and leaf litter chemistry: Influences on microbial respiration and net nitrogen mineralization

    SciTech Connect

    Randlett, D.L.; Zak, D.R.; Pregitzer, K.S.; Curtis, P.S.

    1996-09-01

    Elevated atmospheric CO{sub 2} has the potential to influence rates of C and N cycling in terrestrial ecosystems by altering plant litter chemistry and slowing rates of organic matter decomposition. We tested the hypothesis that the chemistry of leaf litter produced at elevated CO{sub 2} would slow C and N transformations in soil. Soils were amended with Populus leaf produced under two levels of atmospheric CO{sub 2} (ambient and twice-ambient) and soil N availability (low and high). Kinetic parameters for microbial respiration and net N mineralization were determined on soil with and without litter during a 32-wk lab incubation. Product accumulation curves for CO{sub 2}-C and inorganic N were fit to a first order rate equation [y=A(1-e{sup -kt})] using nonlinear regression analyses. Although CO{sub 2} treatment affected soluble sugar concentration in leaf litter (ambient =120 g kg{sup -1}, elevated =130 g kg{sup -1}), it did not affect starch concentration or C/N ratio. Microbial respiration, microbial biomass, and leaf litter C/N ratio were affected by soil N availability but not by atmospheric CO{sub 2}. Net N mineralization was a linear function of time and was not significantly different for leaves grown at ambient (50 mg N kg{sup -1}) and elevated CO{sub 2} (35 mg N kg{sup -1}). Consequently, we found no evidence for the hypothesis that leaf litter produced at elevated atmospheric CO{sub 2} will dampen the rates of C and N cycling in soil. 35 refs., 1 fig., 4 tabs.

  17. Analysis of atmospheric methane from Siberian tower observation using chemistry transport model

    NASA Astrophysics Data System (ADS)

    Ishijima, K.; Sasakawa, M.; Machida, T.; Patra, P. K.; Ito, A.; Ghosh, A.; Morimoto, S.; Aoki, S.; Nakazawa, T.

    2014-12-01

    Atmospheric methane (CH4) is the second greenhouse gas, which is originally a natural atmospheric component, but the amount in the atmosphere has been dramatically increased due to addition of various anthropogenic sources especially after industrialization triggered in 18th century. Such coexistence of both natural and anthropogenic sources at the present make it difficult to quantitatively understand CH4 cycles on the globe. For example, CH4 concentration was increasing in 1990s, became stable in 2000s, and began to increase again from 2007, but discussions on what caused such intriguing long-term variations remain inconclusive. On the other hand, it is well known that wetlands is the largest natural source of CH4. Of them, wetlands in Arctic regions have been recently receiving remarkable attention, because high-latitude regions are more sensitive to global warming than low-latitudes, possibly enhancing CH4 emissions there. In West Siberia, there are large wetland areas significantly contributing to the global CH4 budget. In order to monitor atmospheric CH4 variability, which strongly reflects CH4 emissions from surrounding wetlands, continuous measurements of CH4 concentration from an expanding network of towers (JR-STATION: Japan-Russia Siberian Tall Tower Inland Observation Network) have been conducted mainly in West Siberia since 2004. A previous study on the measurements has revealed that CH4 concentration has large diurnal and seasonal variability, which are driven by seasonally varying wetland and fossil fuel emissions as well as by significant diurnal and seasonal variations of planetary boundary layer height (PBLH). While chemistry transport model can be a useful tool to understand atmospheric CH4 variations in many cases, model simulation for the JR-STATION seems to be slightly challenging, since it is well known that present transport models' capability to reproduce PBLH is not enough. In this study, we validate model transport of the CCSR

  18. The atmospheric chemistry of methyl salicylate—reactions with atomic chlorine and with ozone

    NASA Astrophysics Data System (ADS)

    Canosa-Mas, Carlos E.; Duffy, Justin M.; King, Martin D.; Thompson, Katherine C.; Wayne, Richard P.

    Methyl salicylate is one of a number of semiochemicals, signal molecules, emitted by herbivore-infested plants. These signal molecules attract predators of the herbivore, and the chemicals thus act indirectly as part of the defence mechanism of the plant. Previous studies have shown that ozone damage to plants can also elicit the emission of signal molecules. The fate of these signal molecules in the atmosphere is not known. Preliminary studies have been undertaken to examine the atmospheric chemistry of methyl salicylate for the first time. Rate coefficients for the reaction of methyl salicylate with atomic chlorine and with ozone have been determined; the values are (2.8±0.3)×10 -12 and ˜4×10 -21 cm 3 molecule -1 s -1. These results suggest that neither reaction with atomic chlorine nor reaction with ozone will provide important loss routes for methyl salicylate in the atmosphere. The possible importance of photolysis of methyl salicylate in the atmosphere is considered.

  19. Isotopic links between atmospheric chemistry and the deep sulphur cycle on Mars.

    PubMed

    Franz, Heather B; Kim, Sang-Tae; Farquhar, James; Day, James M D; Economos, Rita C; McKeegan, Kevin D; Schmitt, Axel K; Irving, Anthony J; Hoek, Joost; Dottin, James

    2014-04-17

    The geochemistry of Martian meteorites provides a wealth of information about the solid planet and the surface and atmospheric processes that occurred on Mars. The degree to which Martian magmas may have assimilated crustal material, thus altering the geochemical signatures acquired from their mantle sources, is unclear. This issue features prominently in efforts to understand whether the source of light rare-earth elements in enriched shergottites lies in crustal material incorporated into melts or in mixing between enriched and depleted mantle reservoirs. Sulphur isotope systematics offer insight into some aspects of crustal assimilation. The presence of igneous sulphides in Martian meteorites with sulphur isotope signatures indicative of mass-independent fractionation suggests the assimilation of sulphur both during passage of magmas through the crust of Mars and at sites of emplacement. Here we report isotopic analyses of 40 Martian meteorites that represent more than half of the distinct known Martian meteorites, including 30 shergottites (28 plus 2 pairs, where pairs are separate fragments of a single meteorite), 8 nakhlites (5 plus 3 pairs), Allan Hills 84001 and Chassigny. Our data provide strong evidence that assimilation of sulphur into Martian magmas was a common occurrence throughout much of the planet's history. The signature of mass-independent fractionation observed also indicates that the atmospheric imprint of photochemical processing preserved in Martian meteoritic sulphide and sulphate is distinct from that observed in terrestrial analogues, suggesting fundamental differences between the dominant sulphur chemistry in the atmosphere of Mars and that in the atmosphere of Earth. PMID:24740066

  20. Maillard Chemistry in Clouds and Aqueous Aerosol As a Source of Atmospheric Humic-Like Substances.

    PubMed

    Hawkins, Lelia N; Lemire, Amanda N; Galloway, Melissa M; Corrigan, Ashley L; Turley, Jacob J; Espelien, Brenna M; De Haan, David O

    2016-07-19

    The reported optical, physical, and chemical properties of aqueous Maillard reaction mixtures of small aldehydes (glyoxal, methylglyoxal, and glycolaldehyde) with ammonium sulfate and amines are compared with those of aqueous extracts of ambient aerosol (water-soluble organic carbon, WSOC) and the humic-like substances (HULIS) fraction of WSOC. Using a combination of new and previously published measurements, we examine fluorescence, X-ray absorbance, UV/vis, and IR spectra, complex refractive indices, (1)H and (13)C NMR spectra, thermograms, aerosol and electrospray ionization mass spectra, surface activity, and hygroscopicity. Atmospheric WSOC and HULIS encompass a range of properties, but in almost every case aqueous aldehyde-amine reaction mixtures are squarely within this range. Notable exceptions are the higher UV/visible absorbance wavelength dependence (Angström coefficients) observed for methylglyoxal reaction mixtures, the lack of surface activity of glyoxal reaction mixtures, and the higher N/C ratios of aldehyde-amine reaction products relative to atmospheric WSOC and HULIS extracts. The overall optical, physical, and chemical similarities are consistent with, but not demonstrative of, Maillard chemistry being a significant secondary source of atmospheric HULIS. However, the higher N/C ratios of aldehyde-amine reaction products limits the source strength to ≤50% of atmospheric HULIS, assuming that other sources of HULIS incorporate only negligible quantities of nitrogen. PMID:27227348

  1. Heterogeneous chemistry of atmospheric mineral dust particles and their resulting cloud-nucleation properties

    NASA Astrophysics Data System (ADS)

    Sullivan, Ryan Christopher

    Mineral dust particles are a major component of tropospheric aerosol mass and affect regional and global atmospheric chemistry and climate. Dust particles experience heterogeneous reactions with atmospheric gases that alter the gas and particle-phase chemistry. These in turn influence the warm and cold cloud nucleation ability and optical properties of the dust particles. This dissertation investigates the atmospheric chemistry of mineral dust particles and their role in warm cloud nucleation through a combination of synergistic field measurements, laboratory experiments, and theoretical modeling. In-situ measurements made with a single-particle mass spectrometer during the ACE-Asia field campaign in 2001 provide the motivation for this work. The observed mixing state of the individual ambient particles with secondary organic and inorganic components is described in Chapter 2. A large Asian dust storm occurred during the campaign and produced dramatic changes in the aerosol's composition and mixing state. The effect of particle size and mineralogy on the atmospheric processing of individual dust particles is explored in Chapters 3 & 4. Sulfate was found to accumulate preferentially in submicron iron and aluminosilicate-rich dust particles, while nitrate and chloride were enriched in supermicron calcite-rich dust. The mineral dust (and sea salt particles) were also enriched in oxalic acid, the dominant component of water soluble organic carbon. Chapter 5 explores the roles of gas-phase photochemistry and partitioning of the diacids to the alkaline particles in producing this unique behavior. The effect of the dust's mixing state with secondary organic and inorganic components on the dust particles' solubility, hygroscopicity, and thus warm cloud nucleation properties is explored experimentally and theoretically in Chapter 6. Cloud condensation nucleation (CCN) activation curves revealed that while calcium nitrate and calcium chloride particles were very hygroscopic

  2. Investigating the Chemical Pathways to PAH- and PANH-Based Aerosols in Titan's Atmospheric chemistry

    NASA Technical Reports Server (NTRS)

    Sciamma-O'Brien, Ella Marion; Contreras, Cesar; Ricketts, Claire Louise; Salama, Farid

    2011-01-01

    A complex organic chemistry between Titan's two main constituents, N2 and CH4, leads to the production of more complex molecules and subsequently to solid organic aerosols. These aerosols are at the origin of the haze layers giving Titan its characteristic orange color. In situ measurements by the Ion Neutral Mass Spectrometer (INMS) and Cassini Plasma Spectrometer (CAPS) instruments onboard Cassini have revealed the presence of large amounts of neutral, positively and negatively charged heavy molecules in the ionosphere of Titan. In particular, benzene (C6H6) and toluene (C6H5CH3), which are critical precursors of polycyclic aromatic hydrocarbon (PAH) compounds, have been detected, suggesting that PAHs might play a role in the production of Titan s aerosols. Moreover, results from numerical models as well as laboratory simulations of Titan s atmospheric chemistry are also suggesting chemical pathways that link the simple precursor molecules resulting from the first steps of the N2-CH4 chemistry (C2H2, C2H4, HCN ...) to benzene, and to PAHs and nitrogen-containing PAHs (or PANHs) as precursors to the production of solid aerosols.

  3. Specification of Biogenic VOC Emission Data in the Coupled System of Regional Climate and Atmospheric Chemistry/Aerosols Model

    NASA Astrophysics Data System (ADS)

    Zemankova, K.; Huszar, P.

    2009-12-01

    Coupling of regional climate model RegCM (Pal et al., 2007) and atmospheric chemistry/aerosols model CAMx (Environ, 2006) is being developed at our department under the CECILIA project (EC 6th FP) with the aim to study climate forcing due to atmospheric chemistry/aerosols on regional scale. Regional climate model RegCM with the resolution of 10 km drives transport, chemistry and dry/wet deposition of the CAMx model being operated on the Central and Eastern European domain and consequently the radiative active agents from the CAMx model enter the radiative transfer schemes for the calculation of heating rate changes in the regional climate model. In order to increase the accuracy of land cover data in this model system, a new input dataset has been prepared and used for the calculation of emissions of volatile organic compounds (VOCs) from natural sources. This dataset is mainly based on the single tree species database from the european project of JRC in Ispra - Agriculture, Forestry, and Other Land Uses in Europe (AFOLU) which covers most of the model domain. For the locations where AFOLU data were not available, i.e. basically non-EU areas, the USGS Eurasia land cover database has been used. Both databases are available in 1 km resolution. Emission factors for new land cover categories were obtained either from the laboratory measurements or from the literature. The Guenther et al. (1995) model algorithm has been used for the calculation of biogenic VOC (BVOC) emission fluxes. Effects of new land cover and BVOC emission data on the CAMx model simulations of low level ozone in the year 2000 have been studied. Improvement of model results when compared with the measured data may be seen, especially in the simulation of extreme values such as ozone summer maxima. References: - ENVIRON Corp., 2006. CAMx User’s Guide, version 4.40 - Guenther A., Hewitt N., Erickson D., Fall R., Geron Ch., Graedel T., Harley P., Klinger L., Lerdau M., McKay W. A., Pierce T., Scholes

  4. Comparative Experimental Investigation of Titan's Atmospheric Chemistry Driven by Solar EUV Radiation and Energetic Electron Precipitation

    NASA Astrophysics Data System (ADS)

    Imanaka, Hiroshi; Lavvas, P.; Yelle, R. V.; Smith, M. A.

    2010-10-01

    The observations by the Cassini Ion Neutral Mass Spectrometer (INMS) and the Cassini Plasma Spectrometer (CAPS) clearly demonstrate the importance of complex organic chemistry in the upper atmosphere of Titan; a complex coupling of neutral and ion chemistry for organic aerosol generation induced by EUV photons and Saturn's magnetospheric charged particles. To understand the dominant energy source for aerosol formation and its formation chemistry, we comparatively investigate the chemical mechanism in N2/CH4 gas mixtures resulting from EUV-VUV synchrotron radiation (50-150 nm) and tunable mono-energetic electron beam irradiation (5 eV - 2000 eV). These excitation energy sources cover the dominant energy source available in Titan's upper atmosphere. Our previous study of the EUV-VUV photolysis of N2/CH4 gas mixtures revealed the unique role of nitrogen photoionization in the catalytic formation of complex hydrocarbons and in the major nitrogen fixation process in Titan's upper atmosphere (Imanaka and Smith, 2007, 2009, 2010). However, relative roles of ion-molecule reactions and radical/neutral reactions in such complex chemistry remain to be determined. We characterized the electron energy distribution by conducting the Langmuir probe measurements. Degradation of the primary photoelectron from N2 photoionization at 20.6 eV photons is clearly observed, and the electron density rapidly decreases down to 109-10 cm-3, which suggests the complex coupling of ion-molecular reactions and dissociative ion-electron recombination reactions for the observed development of complex organic molecules. The electron beam irradiation experiments at energy larger than 200 eV shows distinct gaseous product distribution with nitrogenated gaseous species from those with EUV irradiation products. The generation of secondary electrons and multiple inelastic collisions of fast electrons might increases the nitrogen fixation efficiency. The much less stringent spin selection rules could

  5. Constraining the Sources and Sinks of Atmospheric Methane Using Stable Isotope Observations and Chemistry Climate Modeling

    NASA Astrophysics Data System (ADS)

    Feinberg, A.; Coulon, A.; Stenke, A.; Peter, T.

    2015-12-01

    Methane acts as both a greenhouse gas and a driver of atmospheric chemistry. There is a lack of consensus for the explanation behind the atmospheric methane trend in recent years (1980-2010). High uncertainties are associated with the magnitudes of individual methane source and sink processes. Methane isotopes have the potential to distinguish between the different methane fluxes, as each flux is characterized by an isotopic signature. Methane emissions from each source category are expressed explicitly in a chemistry climate model SOCOL, including wetlands, rice paddies, biomass burning, industry, etc. The model includes 48 methane tracers based on source type and geographical origin in order to track methane after it has been emitted. SOCOL simulations for the years 1980-2010 are performed in "nudged mode", so that model dynamics reflect observed meteorology. Available database estimates of the various surface emission fluxes are inputted into SOCOL. The model diagnostic methane tracers are compared to methane isotope observations from measurement networks. Inconsistencies between the model results and observations point to deficiencies in the available emission estimates or model sink processes. Because of their dependence on the OH sink, deuterated methane observations and methyl chloroform tracers are used to investigate the variability of OH mixing ratios in the model and the real world. The analysis examines the validity of the methane source and sink category estimates over the last 30 years.

  6. Contrail: A Module from Physical Chemistry On-Line Project

    ERIC Educational Resources Information Center

    Chen, Franklin; Zielinski, Theresa Julia; Long, George

    2007-01-01

    The impact of contrails on Earth's climate is researched to understand the active area. It is suggested that the process of contrail formation involves combustion, cooling and ice formation, which are good comprehensive learning exercise for physical chemistry students.

  7. Independent Learning Project for Advanced Chemistry (ILPAC). Teachers' and Technicians' Notes for First Year Units.

    ERIC Educational Resources Information Center

    Inner London Education Authority (England).

    The Independent Learning Project for Advanced Chemistry (ILPAC) has produced units of study for students in A-level chemistry. Students completing ILPAC units assume a greater responsibility for their own learning and can work, to some extent, at their own pace. By providing guidance, and detailed solutions to exercises in the units, supported by…

  8. On the one-dimensional chemistry-diffusion model in planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Zhang, Xi; Showman, Adam

    Most of the current atmospheric chemistry models for planets (e.g., Krasnopolsky & Parshev 1981; Yung et al., 1984; Lavvas et al., 2008) and exo-planets (e.g., Moses et al., 2011; Line et al., 2011; Hu et al., 2012) adopt a one-dimensional (1D) chemistry-diffusion approach in the vertical coordinate such as pressure or altitude. Although only a crude approximation, these 1D models have succeeded in explaining the global-averaged vertical profiles of many chemical species in observations. One of the important assumptions of these models is that, all chemical species are transported via the same eddy diffusion profile. Here we show that, as also noticed in the Earth community (e.g., Holton 1986), in the presence of horizontal transport driven by eddies in the middle atmospheres such as the stratospheres on Earth and Titan, this “homogenous eddy diffusion” assumption generally breaks down. Instead, the eddy diffusion should depend both on the horizontal eddy mixing and the chemical lifetime of the species. It implies that the long-lived species and short-lived species could have significantly different eddy diffusion profiles. We show analytically why this new approach is more physically based. We also show numerically why the old approach fails compared with the globally averaged results from a more realistic two-dimensional (2D) simulation using the state-of-art Caltech/JPL 2D chemistry-diffusion-advection model (Zhang et al., 2013), and discuss the possible consequences. This research was supported by the Bisgrove Scholar Program in the University of Arizona.

  9. The Right Chemistry. Lawn Care Project Brings Science down to Earth.

    ERIC Educational Resources Information Center

    Dollar, David

    1992-01-01

    At Southwest High School in Fort Worth, Texas, an applied learning project enables chemistry students to determine the most effective, economical, and environmentally safe fertilizer for the lawns of schools in the district. (SK)

  10. National Atmospheric Deposition Program (NADP) Networks: Data on the chemistry of precipitation

    DOE Data Explorer

    The National Atmospheric Deposition Program/National Trends Network (NADP/NTN) is a nationwide network of sites collecting data on the chemistry of precipitation for monitoring of geographical and temporal long-term trends. The precipitation at each station is collected weekly according to strict clean-handling procedures. It is then sent to the Central Analytical Laboratory where it is analyzed for hydrogen (acidity as pH), sulfate, nitrate, ammonium, chloride, and base cations (such as calcium, magnesium, potassium and sodium). The network is a cooperative effort between many different groups, including the State Agricultural Experiment Stations, U.S. Geological Survey, U.S. Department of Agriculture, and numerous other governmental and private entities. DOE is one of these cooperating agencies, though it plays a smaller funding role than some of the other federal sources. Since 1978, the NADP/NTN has grown from 22 stations to over 250 sites spanning the continental United States, Alaska, and Puerto Rico, and the Virgin Islands. The National Atmospheric Deposition Program has also expanded its sampling to two additional networks: 1) the Mercury Deposition Network (MDN), currently with over 90 sites, was formed in 1995 to collect weekly samples of precipitation which are analyzed by Frontier Geosciences for total mercury, and 2) the Atmospheric Integrated Research Monitoring Network (AIRMoN), formed for the purpose of studying precipitation chemistry trends with greater temporal resolution than the NTN. [taken from the NADP History and Overview page at http://nadp.sws.uiuc.edu/nadpoverview.asp] Data from these networks are freely available in via customized search interfaces linked to interactive maps of the stations in the three networks. Animated Isopleth maps in Flash and PowerPoint are also available to display concentrations and depositions various substances such as sulfate, nitrate, etc. (Specialized Interface)

  11. Fire risk, atmospheric chemistry and radiative forcing assessment of wildfires in eastern Mediterranean

    NASA Astrophysics Data System (ADS)

    Athanasopoulou, E.; Rieger, D.; Walter, C.; Vogel, H.; Karali, A.; Hatzaki, M.; Gerasopoulos, E.; Vogel, B.; Giannakopoulos, C.; Gratsea, M.; Roussos, A.

    2014-10-01

    The current research study aims at investigating the atmospheric implications of a major fire event in the Mediterranean area. For this purpose, a regional aerosol model coupled online with meteorology (COSMO-ART) is applied over Greece during late summer 2007. Fire risk model results proved to be adequate in reproducing the highly destructive event, which supports further applications for national meteorological forecasts and early warning systems for fire prevention. Columnar aerosol loading field predictions are consistent with satellite maps, which further allows for the correlation of this wildfire event to the atmospheric chemistry and the radiative forcing. Gaseous chemistry resembles that in urban environments and led to nitrogen dioxide and ozone exceedances in several cities in proximity to and downwind the fire spots, respectively. Influence in Athens is found significant from the Euboean plume (45% of total surface PM10) and small (5%) from the fires in Peloponnese. Fire events are indicated by sharp increases in organic to elemental carbon (6), together with sharp decreases in secondary to total organic components (0.1), in comparison to their values during the pre- and post-fire period over Athens (1 and 0.6, respectively). The change in the radiative budget induced by the fire plume is found negative (3-day-average value up to -10 W m-2). Direct heat input is found negligible, thus the net temperature effect is also negative over land (-0.5 K). Nevertheless, positive temperature changes are found overseas (hourly value up to +2 K), due to the amplified radiation absorption by aged soot, coupled to the intense stabilization of the atmosphere above the sea surface.

  12. The Titan Haze Simulation experiment: laboratory simulation of Titan's atmospheric chemistry at low temperature

    NASA Astrophysics Data System (ADS)

    Sciamma-O'Brien, E.; Contreras, C. S.; Ricketts, C. L.; Salama, F.

    2012-04-01

    In Titan’s atmosphere, a complex organic chemistry between its two main constituents, N2 and CH4, leads to the production of heavy molecules and subsequently to solid organic aerosols. Several instruments onboard Cassini have detected neutral, positively and negatively charged particles and heavy molecules in the ionosphere of Titan[1,2]. In particular, the presence of benzene (C6H6) and toluene (C6H5CH3)[3], which are critical precursors of polycyclic aromatic hydrocarbon (PAH) compounds, suggests that PAHs might play a role in the production of Titan’s aerosols. The Titan Haze Simulation (THS) experiment has been developed at NASA Ames’ Cosmic Simulation facility (COSmIC) to study the chemical pathways that link the simple precursor molecules resulting from the first steps of the N2-CH4 chemistry (C2H2, C2H4, HCN…) to benzene, and to PAHs and nitrogen-containing PAHs (or PANHs) as precursors to the production of solid aerosols. In the THS experiment, Titan’s atmospheric chemistry is simulated by plasma in the stream of a supersonic jet expansion. With this unique design, the gas mixture is cooled to Titan-like temperature (~150K) before inducing the chemistry by plasma discharge. Different gas mixtures containing the first products of Titan’s N2-CH4 chemistry but also much heavier molecules like PAHs or PANHs can be injected to study specific chemical reactions. The products of the chemistry are detected and studied using two complementary techniques: Cavity Ring Down Spectroscopy[4] and Time-Of-Flight Mass Spectrometry[5]. Thin tholin deposits are also produced in the THS experiment and can be analyzed by Gas Chromatography-Mass Spectrometry (GC-MS) and Scanning Electron Microscopy (SEM). We will present the results of ongoing mass spectrometry studies on the THS experiment using different gas mixtures: N2-CH4, N2-C2H2, N2-C2H4, N2-C2H6, N2-C6H6, and similar mixtures with an N2-CH4 (90:10) mixture instead of pure N2, to study specific pathways

  13. The ENVISAT Atmospheric Chemistry mission (GOMOS, MIPAS and SCIAMACHY) -Instrument status and mission evolution

    NASA Astrophysics Data System (ADS)

    Dehn, Angelika

    The ENVISAT ESA's satellite was launched on a polar orbit on March 2002. It carries on-board three atmospheric chemistry instruments: GOMOS, MIPAS and SCIAMACHY [1]. At the present time, although the mission expected lifetime of 5 years has been already exceeded, all the payload modules are in good to excellent status. The only limiting factor is the available fuel that is used for orbit control manoeuvre. A new strategy was proposed [2] that will allow to save fuel and to extend the mission up to 2013. Following this strategy, the altitude of the orbit will be lowered by 17 km starting from end of 2010 and the inclination will be allowed to drift. The new orbit scenario will result in a new repeating cycle with a variation of the Mean Local Solar Time (MLST). This will have an impact on both the in-flight operations, on the science data and on the mission. The simulations carried out for the atmospheric chemistry instruments show that the new orbit strategy will neither have a significant impact in the instrument operations nor on the quality of the science data. Therefore we expect that the atmospheric mission will continue nominally until the end of the platform life time, providing to the scientist a unique dataset of the most important geophysical parameters (e.g., trace gases, clouds, and aerosol) spanning a time interval of about 11 years. The aim of this paper is to review the overall ENVISAT atmospheric mission status for the past, present and future. The evolution of the instrument performances since launch will be analyzed with focus on the life-limited items monitoring. The tuning of the instrument in-flight operations decided to cope with instrument degradation or scientific needs will be described. The lessons learned on how to operate and monitor the instruments will be highlighted. Finally the expected evolution of the instrument performances until the ENVISAT end-of-life will be discussed. [1] H. Nett, J. Frerick, T. Paulsen, and G. Levrini, "The

  14. The ENVISAT Atmospheric Chemistry mission (GOMOS, MIPAS and SCIAMACHY) - Instrument status and mission evolution

    NASA Astrophysics Data System (ADS)

    Niro, F.

    2009-04-01

    The ENVISAT ESA's satellite was launched on a polar orbit on March 2002. It carries on-board three atmospheric chemistry instruments: GOMOS, MIPAS and SCIAMACHY [1]. At the present time, although the mission expected lifetime of 5 years has been already exceeded, all the payload modules are in good to excellent status. The only limiting factor is the available fuel that is used for orbit control manoeuvre. Recently a new strategy was proposed [2] that will allow to save fuel and to extend the mission up to 2013. Following this strategy, the altitude of the orbit will be lowered by 17 km starting from end of 2010 and the inclination will be allowed to drift. The new orbit scenario will result in a new repeating cycle with a variation of the Mean Local Solar Time (MLST). This will have an impact on both the in-flight operations, on the science data and on the mission. The simulations carried out for the atmospheric chemistry instruments show that the new orbit strategy will neither have a significant impact in the instrument operations nor on the quality of the science data. Therefore we expect that the atmospheric mission will continue nominally until the end of the platform life time, providing to the scientist a unique dataset of the most important geophysical parameters (e.g., trace gases, clouds, and aerosol) spanning a time interval of about 11 years. The aim of this paper is to review the overall ENVISAT atmospheric mission status for the past, present and future. The evolution of the instrument performances since launch will be analyzed with focus on the life-limited items monitoring. The tuning of the instrument in-flight operations decided to cope with instrument degradation or scientific needs will be described. The lessons learned on how to operate and monitor the instruments will be highlighted. Finally the expected evolution of the instrument performances until the ENVISAT end-of-life will be discussed. [1] H. Nett, J. Frerick, T. Paulsen, and G

  15. Cometary airbursts and atmospheric chemistry: Tunguska and a candidate Younger Dryas event

    NASA Astrophysics Data System (ADS)

    Melott, A.

    2009-12-01

    We estimate atmospheric chemistry changes from ionization at the 1908 Tunguska airburst event, finding agreement with nitrate enhancement in GISP2H and GISP2 ice cores and noting an unexplained accompanying ammonium spike. We then consider the candidate Younger Dryas comet impact. The estimated NOx production and O3 depletion are large, beyond accurate extrapolation. A modest nitrate deposition signal exists in ice core data. The predicted very large impulsive deposition might be visible in higher resolution data. Ammonium has been attributed to biomass burning, and found coincident with nitrate spikes at YD onset in both the GRIP and GISP2 ice cores. A similar result is well-resolved in Tunguska ice core data, but the Tunguska forest fire was far too small to account for this. Direct input of ammonia from a comet into the atmosphere is consistent with the spike for the candidate YD object, but also inadequate for Tunguska. An analog of the Haber process with hydrogen contributed by the cometary or surface water, atmospheric nitrogen, high temperatures, pressures, and the possible presence of catalytic iron from a comet could in principle divert a variable fraction of the reaction products to ammonia, accounting for ice core data in both events.

  16. The Role of Nitrogen in Titan’s Upper Atmospheric Hydrocarbon Chemistry Over the Solar Cycle

    NASA Astrophysics Data System (ADS)

    Luspay-Kuti, A.; Mandt, K. E.; Westlake, J. H.; Plessis, S.; Greathouse, T. K.

    2016-06-01

    Titan’s thermospheric photochemistry is primarily driven by solar radiation. Similarly to other planetary atmospheres, such as Mars’, Titan’s atmospheric structure is also directly affected by variations in the solar extreme-UV/UV output in response to the 11-year-long solar cycle. Here, we investigate the influence of nitrogen on the vertical production, loss, and abundance profiles of hydrocarbons as a function of the solar cycle. Our results show that changes in the atmospheric nitrogen atomic density (primarily in its ground state N(4S)) as a result of photon flux variations have important implications for the production of several minor hydrocarbons. The solar minimum enhancement of CH3, C2H6, and C3H8, despite the lower CH4 photodissociation rates compared with solar maximum conditions, is explained by the role of N(4S). N(4S) indirectly controls the altitude of termolecular versus bimolecular chemical regimes through its relationship with CH3. When in higher abundance during solar maximum at lower altitudes, N(4S) increases the importance of bimolecular CH3 + N(4S) reactions producing HCN and H2CN. The subsequent remarkable CH3 loss and decrease in the CH3 abundance at lower altitudes during solar maximum affects the overall hydrocarbon chemistry.

  17. ATMOSPHERIC CHEMISTRY IN GIANT PLANETS, BROWN DWARFS, AND LOW-MASS DWARF STARS. III. IRON, MAGNESIUM, AND SILICON

    SciTech Connect

    Visscher, Channon; Lodders, Katharina; Fegley, Bruce E-mail: lodders@wustl.ed

    2010-06-20

    We use thermochemical equilibrium calculations to model iron, magnesium, and silicon chemistry in the atmospheres of giant planets, brown dwarfs, extrasolar giant planets (EGPs), and low-mass stars. The behavior of individual Fe-, Mg-, and Si-bearing gases and condensates is determined as a function of temperature, pressure, and metallicity. Our equilibrium results are thus independent of any particular model atmosphere. The condensation of Fe metal strongly affects iron chemistry by efficiently removing Fe-bearing species from the gas phase. Monatomic Fe is the most abundant Fe-bearing gas throughout the atmospheres of EGPs and L dwarfs, and in the deep atmospheres of giant planets and T dwarfs. Mg- and Si-bearing gases are effectively removed from the atmosphere by forsterite (Mg{sub 2}SiO{sub 4}) and enstatite (MgSiO{sub 3}) cloud formation. Monatomic Mg is the dominant magnesium gas throughout the atmospheres of EGPs and L dwarfs and in the deep atmospheres of giant planets and T dwarfs. Silicon monoxide (SiO) is the most abundant Si-bearing gas in the deep atmospheres of brown dwarfs and EGPs, whereas SiH{sub 4} is dominant in the deep atmosphere of Jupiter and other gas giant planets. Several other Fe-, Mg-, and Si-bearing gases become increasingly important with decreasing effective temperature. In principle, a number of Fe, Mg, and Si gases are potential tracers of weather or diagnostic of temperature in substellar atmospheres.

  18. Simulating Titan’s atmospheric chemistry at low temperature (200K)

    NASA Astrophysics Data System (ADS)

    Sciamma-O'Brien, Ella; Upton, Kathleen T.; Beauchamp, Jesse L.; Salama, Farid

    2016-06-01

    We present our latest results on the Titan Haze Simulation (THS) experiment developed on the COSmIC simulation chamber at NASA Ames Research Center. In Titan’s atmosphere, a complex organic chemistry induced by UV radiation and electron bombardment occurs between N2 and CH4 and leads to the production of larger molecules and solid aerosols. In the THS, the chemistry is simulated by pulsed plasma in the stream of a supersonic expansion, at Titan-like temperature (150 K). The residence time of the gas in the pulsed plasma discharge is on the order of 3 µs, hence the chemistry is truncated allowing us to probe the first and intermediate steps of the chemistry by adding heavier precursors into the initial N2-CH4 gas mixture.Two complementary studies of the gas phase and solid phase products have been performed in 4 different gas mixtures: N2-CH4, N2-CH4-C2H2, N2-CH4-C6H6 and N2-CH4-C2H2-C6H6 using a combination of in situ and ex situ diagnostics. The mass spectrometry analysis of the gas phase was the first to demonstrate that the THS is a unique tool to monitor the different steps of the N2-CH4 chemistry (Sciamma-O’Brien et al. 2014). The results of the solid phase study are consistent with the chemical growth evolution observed in the gas phase. Grains and aggregates that form in the gas phase were jet deposited on various substrates then collected for ex situ analysis. Scanning Electron Microscopy images have shown that more complex mixtures produce larger aggregates (100-500 nm in N2-CH4, up to 5 µm in N2-CH4-C2H2-C6H6). Moreover, the morphology of the grains seems to depend on the precursors, which could have a large impact for Titan’s models. We will present the latest results of the X-ray Absorption Near Edge Structure measurements, that show the different functional groups present in our samples and give the C/N ratio; as well as the Direct Analysis in Real Time Mass Spectrometry coupled with Collision Induced Dissociation analyses that have been

  19. A review of uncertainties in atmospheric modeling of mercury chemistry I. Uncertainties in existing kinetic parameters - Fundamental limitations and the importance of heterogeneous chemistry

    NASA Astrophysics Data System (ADS)

    Subir, Mahamud; Ariya, Parisa A.; Dastoor, Ashu P.

    2011-10-01

    Mercury and its related compounds are widely recognized as global pollutants. The accurate atmospheric modeling of its transport and fate has been the subject of much research throughout the last decade. Atmospheric gas, aqueous and heterogeneous chemistry are expected to occur for Hg-containing species and accurate implementation of their chemical parameters is essential for realistic modeling of mercury cycling. Although significant progress has been made, the current state of knowledge of mercury chemistry exhibits numerous uncertainties. The objective of this two-part review is to explore the sources of uncertainty from the viewpoint of mercury chemistry. In this first part, we assess the discrepancy that exists in the currently available mercury kinetic parameters for the gas and aqueous phases. Theoretical and experimental approaches of rate constant determination exhibit various levels of limitation and accuracy. We present an overview of the available techniques and the assumptions and shortcomings associated with these methods in order to assist the atmospheric modellers. We review specific mercury oxidation and reduction reactions that have been investigated and are commonly implemented in mercury models with respect to the uncertainties associated with them. We reveal that for most of these mercury reactions our current state of knowledge reflects a lack of proper understanding of their mechanisms. Atmospheric heterogeneity is a topic of great importance and we elaborate upon it in part II of this review.

  20. Volatile organic compounds in the New England troposphere: Atmospheric chemistry and measurement techniques

    NASA Astrophysics Data System (ADS)

    Ambrose, Jesse L.

    Atmospheric measurements made at Appledore Island, Maine were used to investigate nighttime nitrate radical (NO3) chemistry and its significance for the nitrogen oxides (NOx = NO + NO2) budget in the Gulf of Maine region during the summer of 2004 International Consortium for Atmospheric Research on Transport and Transformation field campaign. Removal of NOx was strongly dependent on reactions of NO3 with biogenic volatile organic compounds and the fate of dinitrogen pentoxide (N 2O5). For three case studies, temporal profiles of NO 3 were calculated from measured parameters. Comparisons between measured and calculated NO3 mixing ratios highlighted significant uncertainties in the kinetic parameters governing gas-phase and heterogeneous N2O 5 hydrolysis. Removal of NOx was estimated to be ˜11 ppbv day-1, with nighttime chemical pathways contributing ˜50%. Atmospheric measurements made at the AIRMAP atmospheric monitoring station Thompson Farm (THF) during summer, 2004 were used to test the specificity of a proton transfer reaction-mass spectrometer (PTA-MS) for atmospheric toluene measurements under conditions often dominated by biogenic emissions. Quantitative estimates were made of potential interferences in the PTR-MS toluene measurements related to sampling and analysis of monoterpenes, including fragmentation of the monoterpenes and some of their primary carbonyl oxidation products in the PTR-MS drift tube. The analysis supported only minor interferences from the investigated fragmentation sources, suggesting that toluene can be reliably quantified by PTR-MS with the operating parameters used, under the ambient compositions probed. This work extends the range of field conditions under which PTR-MS validation studies have been conducted. A GC instrument was developed for measurement of hydrogen cyanide (HCN) in the lower atmosphere. Its major features include a cold temperature analyte enrichment system, a robust porous polymer stationary phase capillary

  1. UNESCO Chemistry Teaching Project in Asia: Experiments on Nuclear Science.

    ERIC Educational Resources Information Center

    Dhabanandana, Salag

    This teacher's guide on nuclear science is divided into two parts. The first part is a discussion of some of the concepts in nuclear chemistry including radioactivity, types of disintegration, radioactive decay and growth, and tracer techniques. The relevant experiments involving the use of radioisotopes are presented in the second part. The…

  2. Science and adventure with British Exploring in Arctic Norway: Atmospheric Chemistry research with Young people

    NASA Astrophysics Data System (ADS)

    Fleming, Zoe

    2013-04-01

    British Exploring (formerly known as British Schools Exploring Society) has been running expeditions for young people since 1932 and presently runs as many as seven expeditions a year on several continents to remote locations. Some highlights from the Arctic Norway expedition of summer 2012 are presented here, in particular following the Atmospheric Chemistry group that carried out a survey of the pollution in the local environment. The group travelled from fjord to mountain top and spent a few days exploring the Øksfjordjøkelen ice cap. The mobile nature of the expedition meant that the science had to become back-pack science, carried from one remote camp-site to another but this still allowed some cutting-edge science to be carried out that was linked with academic research.

  3. Gas-to-Particle Conversion in Surface Discharge Nonthermal Plasmas and Its Implications for Atmospheric Chemistry

    PubMed Central

    Kim, Hyun-Ha; Ogata, Atsushi

    2011-01-01

    This paper presents some experimental data on gas-to-particle conversion of benzene using nonthermal plasma (NTP) technology and discusses the possibility of its technical application in atmospheric chemistry. Aerosol measurement using a differential mobility analyzer (DMA) revealed that the parts of benzene molecules were converted into a nanometer-sized aerosol. Aerosol formation was found to be highly related with the missing part in carbon balance. Scanning electron microscopy analysis showed that the aerosols formed in synthetic humid air are the collection of nanoparticles. The carbonyl band (C=O) was found to be an important chemical constituent in the aerosol. The potential of the NTP as an accelerated test tool in studying secondary organic aerosol (SOA) formation from VOCs will be also addressed. PMID:22163781

  4. Two-dimensional atmospheric transport and chemistry model - Numerical experiments with a new advection algorithm

    NASA Technical Reports Server (NTRS)

    Shia, Run-Lie; Ha, Yuk Lung; Wen, Jun-Shan; Yung, Yuk L.

    1990-01-01

    Extensive testing of the advective scheme proposed by Prather (1986) has been carried out in support of the California Institute of Technology-Jet Propulsion Laboratory two-dimensional model of the middle atmosphere. The original scheme is generalized to include higher-order moments. In addition, it is shown how well the scheme works in the presence of chemistry as well as eddy diffusion. Six types of numerical experiments including simple clock motion and pure advection in two dimensions have been investigated in detail. By comparison with analytic solutions, it is shown that the new algorithm can faithfully preserve concentration profiles, has essentially no numerical diffusion, and is superior to a typical fourth-order finite difference scheme.

  5. Partial Overhaul and Initial Parallel Optimization of KINETICS, a Coupled Dynamics and Chemistry Atmosphere Model

    NASA Technical Reports Server (NTRS)

    Nguyen, Howard; Willacy, Karen; Allen, Mark

    2012-01-01

    KINETICS is a coupled dynamics and chemistry atmosphere model that is data intensive and computationally demanding. The potential performance gain from using a supercomputer motivates the adaptation from a serial version to a parallelized one. Although the initial parallelization had been done, bottlenecks caused by an abundance of communication calls between processors led to an unfavorable drop in performance. Before starting on the parallel optimization process, a partial overhaul was required because a large emphasis was placed on streamlining the code for user convenience and revising the program to accommodate the new supercomputers at Caltech and JPL. After the first round of optimizations, the partial runtime was reduced by a factor of 23; however, performance gains are dependent on the size of the data, the number of processors requested, and the computer used.

  6. Atmospheric chemistry of enols: a theoretical study of the vinyl alcohol + OH + O(2) reaction mechanism.

    PubMed

    So, Sui; Wille, Uta; da Silva, Gabriel

    2014-06-17

    Enols are emerging as trace atmospheric components that may play a significant role in the formation of organic acids in the atmosphere. We have investigated the hydroxyl radical ((•)OH) initiated oxidation chemistry of the simplest enol, vinyl alcohol (ethenol, CH2═CHOH), using quantum chemical calculations and energy-grained master equation simulations. A lifetime of around 4 h was determined for vinyl alcohol in the presence of tropospheric levels of (•)OH. The reaction proceeds by (•)OH addition at both the α (66%) and β (33%) carbons of the π-system, yielding the C-centered radicals (•)CH2CH(OH)2, and HOCH2C(•)HOH, respectively. Subsequent trapping by O2 leads to the respective peroxyl radicals. About 90% of the chemically activated population of the major peroxyl radical adduct (•)O2CH2CH(OH)2 is predicted to undergo fragmentation to produce formic acid and formaldehyde, with regeneration of (•)OH. The minor peroxyl radical HOCH2C(OO(•))HOH is even less stable and undergoes almost exclusive HO2(•) elimination to form glycolaldehyde (HOCH2CHO). Formation of the latter has not been proposed before in the oxidation of vinyl alcohol. A kinetic mechanism for use in atmospheric modeling is provided, featuring phenomenological rate coefficients for formation of the three main product channels ((•)O2CH2CH(OH)2 [8%]; HC(O)OH + HCHO + (•)OH [56%]; HOCH2CHO + HO2(•) [37%]). Our study supports previous findings that vinyl alcohol should be rapidly removed from the atmosphere by reaction with (•)OH and O2 with glycolaldehyde being identified as a previously unconsidered product. Most importantly, it is shown that direct chemically activated reactions can lead to (•)OH and HO2(•) (HOx) recycling. PMID:24844308

  7. Springtime Arctic Trace Gas Measurements and Comparisons With the Atmospheric Chemistry Experiment on SCISAT

    NASA Astrophysics Data System (ADS)

    Lindenmaier, R.; Batchelor, R.; Strong, K.; Walker, K.; Manney, G.; Daffer, W.

    2009-05-01

    The process of rapid stratospheric ozone loss in the polar regions begins during the polar winter, when dynamical and chemical conditions lead to the formation of reactive chlorine and bromine radicals. Arctic ozone loss varies significantly from year to year because of changing dynamical conditions. Therefore, long-term data sets of Arctic chemical composition measurements are needed to better understand the process of ozone loss, the links between ozone depletion and climate change, and the future evolution of ozone. Solar absorption spectra have been recorded at Eureka, Nunavut in the sunlit part of each year since July 2006, when a Bruker 125HR high-resolution Fourier transform infrared spectrometer was installed at the Polar Environment Atmospheric Research Laboratory (PEARL). Applying the optimal estimation technique, total columns and some vertical profile information are retrieved for a suite of trace gases that are involved in stratospheric ozone depletion. Total columns of O3, HCl, ClONO2, HNO3, and HF will be presented, with a focus on three Canadian Arctic ACE Validation spring campaigns that took place in 2007, 2008, and 2009. Very different dynamical situations were observed over Eureka during these three spring periods: the impact of these conditions on the trace gas measurements will be shown. SCISAT, also known as the Atmospheric Chemistry Experiment (ACE), is a Canadian satellite mission for remote sounding of the Earth's atmosphere and was launched on August 12, 2003. Its primary instrument is a high spectral resolution Fourier Transform Spectrometer (FTS) measuring sequences of atmospheric absorption spectra in solar occultation. From these spectra the vertical distribution of trace gases can be determined. Results of the Bruker 125HR comparisons with the ACE-FTS, made with the purpose of validating the satellite measurements, will be also shown.

  8. Theoretical and modeling studies of the atmospheric chemistry of sulfur oxide and hydroxyl radical systems

    NASA Astrophysics Data System (ADS)

    El-Zanan, Hazem S.

    Models are the tools that integrate our understanding of the atmospheric processes. Box models are utilized frequently and used to simulate the fates and transformation of atmospheric pollutants. The results from models are usually used to produce one integrated system and further help the policy makers to develop control strategies. We have investigated the atmospheric chemistry of the SOx and HOx systems. The results of 15 laboratory experiments that involved the studies of the HO-SO2, reaction have been analyzed. Mixtures of HONO, NO, NO2, H2O, SO2 and CO were photolyzed in synthetic air or in nitrogen containing approximately 50 ppm oxygen. Upon analyzing the data we have found that a very large amount of the observed SO2 oxidation (70.0 +/- 9.1%) can not be explained through the gas phase reaction of HO + SO2 reaction alone. The Regional Atmospheric Chemistry Mechanism, Version 2 (RACM2) was used to investigate additional chemical pathways for the oxidation of SO2. The results indicate that a mechanism(s) involving photochemical heterogeneous reactions could account for the observed additional sulfur dioxide oxidation not accounted for by gas phase oxidation alone. We have also investigated the distribution of the hydroxyl radical in different urban and rural areas. Photolysis of ozone and its reactions with nitrogen oxides and organic compounds, including both anthropogenic and biogenic volatile organic compounds (VOCs), control the mixing ratios of the hydroxyl radical (HO). Measurements of ozone, nitrogen oxides and volatile hydrocarbons from a deciduous forest in July 1999 and six sites located in the San Joaquin Valley obtained during the Central California Ozone Study (CCOS) measured in July 2000 and September 2000 were used to estimate the hydroxyl radical concentrations. Two methods were employed to determine the concentrations: (1) box model simulations and (2) steady state approximation of the species concentrations (Production-Loss Method). The

  9. Streamwater acid-base chemistry and critical loads of atmospheric sulfur deposition in Shenandoah National Park, Virginia.

    PubMed

    Sullivan, T J; Cosby, B J; Webb, J R; Dennis, R L; Bulger, A J; Deviney, F A

    2008-02-01

    A modeling study was conducted to evaluate the acid-base chemistry of streams within Shenandoah National Park, Virginia and to project future responses to sulfur (S) and nitrogen (N) atmospheric emissions controls. Many of the major stream systems in the park have acid neutralizing capacity (ANC) less than 20 microeq/L, levels at which chronic and/or episodic adverse impacts on native brook trout are possible. Model hindcasts suggested that none of these streams had ANC less than 50 microeq/L in 1900. Model projections, based on atmospheric emissions controls representative of laws already enacted as of 2003, suggested that the ANC of those streams simulated to have experienced the largest historical decreases in ANC will increase in the future. The levels of S deposition that were simulated to cause streamwater ANC to increase or decrease to three specified critical levels (0, 20, and 50 microeq/L) ranged from less than zero (ANC level not attainable) to several hundred kg/ha/year, depending on the selected site and its inherent acid-sensitivity, selected ANC endpoint criterion, and evaluation year for which the critical load was calculated. Several of the modeled streams situated on siliciclastic geology exhibited critical loads <0 kg/ha/year to achieve ANC >50 microeq/L in the year 2040, probably due at least in part to base cation losses from watershed soil. The median modeled siliciclastic stream had a calculated critical load to achieve ANC >50 microeq/L in 2100 that was about 3 kg/ha/year, or 77% lower than deposition in 1990, representing the time of model calibration. PMID:17492359

  10. Atmospheric Chemistry of CF3CF=CH2: Reactions With Cl Atoms, OH Radicals and Ozone

    NASA Astrophysics Data System (ADS)

    Sulbaek Andersen, M. P.; Javadi, M. S.; Nielsen, O. J.; Hurley, M. D.; Wallington, T. J.; Singh, R.

    2006-12-01

    The detrimental effects of chlorine chemistry on stratospheric ozone levels are well established. Consequently, there has been a concerted international effort to find replacements for chlorofluorocarbons (CFCs) used previously as electronic equipment cleaners, heat transfer agents, refrigerants, and carrier fluids for lubricant deposition. The replacements for CFCs, hydrofluorocarbons (HFCs) and hydrofluorochlorocarbons (HCFCs), have found widespread industrial use over the past decade. Unsaturated fluorinated hydrocarbons are a new class of compounds which have been developed to replace CFCs and HFCs in air condition units. Prior to any large-scale industrial use an assessment of the atmospheric chemistry, and hence environmental impact, of these compounds is needed. To address this need the atmospheric chemistry of CF3CF=CH2 was investigated. Smog chamber/FTIR techniques were used to determine the following properties for this compound: (i) kinetics of reactions with chlorine atoms (ii) kinetics of reactions with hydroxyl radicals (iii) kinetics of reactions with ozone, (iv) atmospheric lifetimes, (v) atmospheric degradation mechanism, and (vi) global warming potentials. The results are discussed with regard to the environmental impact of CF3CF=CH2 and the atmospheric chemistry of unsaturated fluorinated hydrocarbons.

  11. Three-dimensional behavior of mixing-limited chemistry in the atmosphere

    NASA Astrophysics Data System (ADS)

    Karamchandani, Prakash; Peters, Leonard K.

    The effect of turbulent concentration fluctuations in the near-source region on fast, second-order atmospheric reactions of the type A + B → C is investigated. The correlation term overlineC' AC' B is related to the concentration variance of emitted species A, overlineC' A2. The specific reactions studied are those pertaining to NO-O 3-NO 2 chemistry. A locally one-dimensional finite element method (LOD-FEM) is used to solve the three-dimensional transport/chemistry equations. By evaluating the differences in the photostationary-stale parameter (λ = k 3overlineC NOC O 3/k 1C NO 2) , the effect of the fluctuation term, overlineC NO'C' O 3, is shown to be substantial in the near-source region. The effect initially increases with downwind distance, and then decreases as diffusion and dissipation become dominant. Within the plume itself, the effects are smallest at the core of the plume and are most pronounced at the plume edges. The important dynamical parameters are the eddy diffusivity used for closure of the turbulent species transport equation and the dissipation of turbulent energy that controls the small-scale fluctuations. From a diurnal standpoint, the maximum effect is observed at around noontime, with minimal effects being observed in the early morning and late evening.

  12. New Mass Spectrometry Techniques for Studying Physical Chemistry of Atmospheric Heterogeneous Processes

    SciTech Connect

    Laskin, Julia; Laskin, Alexander; Nizkorodov, Sergey

    2013-03-01

    Ambient particles and droplets have a significant effect on climate, visibility, and human health. Once formed, they undergo continuous transformations through condensation and evaporation of water, uptake of low-volatility organic molecules, and photochemical reactions involving various gaseous and condensed-phase species in the atmosphere. These transformations determine the physical and chemical properties of airborne particles, such as their ability to absorb and scatter solar radiation and nucleate cloud droplets. The complexity, heterogeneity, and size of ambient particles make it challenging to understand the kinetics and mechanisms of their formation and chemical transformations. Mass spectrometry (MS) is a powerful analytical technique that enables detailed chemical characterization of both small and large molecules in complex matrices. We present an overview of new and emerging experimental MS-based approaches for understanding physical chemistry of environmental particles, droplets, and surfaces. In addition, we emphasize the role of fundamental physical chemistry studies in the development of new methods for chemical analysis of ambient particles and droplets.

  13. Natural versus anthropogenic inhalable aerosol chemistry of transboundary East Asian atmospheric outflows into western Japan.

    PubMed

    Moreno, Teresa; Kojima, Tomoko; Querol, Xavier; Alastuey, Andrés; Amato, Fulvio; Gibbons, Wes

    2012-05-01

    The eastward transport of aerosols exported from mainland Asia strongly influences air quality in the Japanese archipelago. The bulk of the inhalable particulate matter (PM(10)) in these intrusions comprises either natural, desert-derived minerals (mostly supermicron silicates) or anthropogenic pollutants (mostly submicron sulphates), in various states of mixing. We analyse PM(10) collected in Kumamoto, SW Japan, during three contrasting types of aerosol intrusions, the first being dominated by desert PM which became increasingly mixed with anthropogenic components as time progressed, the second being a relatively minor event mixing fine, distal desert PM with anthropogenic materials, and the third being dominated by anthropogenic pollutants. Whereas the chemistry of the natural mineral component is characterised by "crustal" elements (Si, Al, Fe, Mg, K, Li, P, Sc, V, Rb, Sr, Zr, Th, lanthanoids), the anthropogenic component is rich in secondary inorganic compounds and more toxic metallic elements (NH(4)(+), SO(4)(2-), As, Pb, Cd, Cu, Zn, Sn, Bi, Sb, and Ge). Some desert-dust (Kosa) intrusions are more calcareous than others, implicating geologically different source areas, and contain enhanced levels of NO(3)(-), probably as supermicron Ca(NO(3))(2) particles produced by chemical reaction between NOx pollutants (mostly from industry and traffic) and carbonate during atmospheric transport. The overall trace element chemistry of aerosol intrusions into Kumamoto shows low V/Rb, low NO(3)(-)/SO(4)(2-), enhanced As levels, and unfractionated La/Ce values, which are all consistent with anthropogenic sources including coal emissions rather than those derived from the refining and combustion of oil fractionates. Geographically dispersed, residual sulphatic plumes of this nature mix with local traffic (revealed by OC and EC concentrations) and industrial emissions and dissipate only slowly, due to the dominance of submicron accumulation mode PM which is atmospherically

  14. Parallelization and load balancing of a comprehensive atmospheric chemistry transport model

    NASA Astrophysics Data System (ADS)

    Elbern, Hendrik

    Chemistry transport models are generally claimed to be well suited for massively parallel processing on distributed memory architectures since the arithmetic-to-communication ratio is usually high. However, this observation proves insufficient to account for an efficient parallel performance with increasing complexity of the model. The modeling of the local state of the atmosphere ensues very different branches of the modules' code and greater differences in the computational work load and, consequently, runtime of individual processors occur to a much larger extent during a time step than reported for meteorological models. Variable emissions, changes in actinic fluxes, and all processes associated with cloud modeling are highly variable in time and space and are identified to induce large load imbalances which severely affect the parallel efficiency. This is more so, when the model domain encompasses more heterogeneous meteorological or regional regimes, which impinge dissimilarly on simulations of atmospheric chemistry processes. These conditions hold for the EURAD model applied in this study, which covers the European continental scale as integration domain. Based on a master-worker configuration with a horizontal grid partitioning approach, a method is proposed where the integration domain of the individual processors is locally adjusted to accommodate for load imbalances. This ensures a minimal communication volume and data exchange only with the next neighbors. The interior boundary adjustments of the processors are combined with routine boundary exchange which is required each time step anyway. Two dynamic load balancing schemes were implemented and compared against a conventional equal area partition and a static load balancing scheme. The methods are devised for massively parallel distributed memory computers of both, Single and Multiple Instruction stream Multiple Data stream (SIMD, MIMD) types. A midsummer episode of highly elevated ozone concentrations

  15. Climatic implications of background acidity and other chemistry derived from electrical studies of the Greenland Ice Core Project ice core

    NASA Astrophysics Data System (ADS)

    Wolff, Eric W.; Moore, John C.; Clausen, Henrik B.; Hammer, Claus U.

    1997-11-01

    High-resolution continuous profiles were obtained on the Greenland Ice Core Project (GRIP) ice core using two different electrical methods. After correction for temperature and density, the electrical conductivity method (ECM) technique responds only to acidity, while dielectric profiling (DEP) responds to acid, ammonium, and chloride. Detailed chemistry on a section of glacial-age ice allows us to confirm the calibration factor for chloride in DEP. Acidity dominates the DEP variability in the Holocene, Allerod/Bolling, and larger interstadials; ammonium dominates in the Younger Dry as, while chloride is the major contributor in cold periods including smaller interstadials. From the electrical signals plotted on a linear timescale we can deduce the background (nonvolcanic) acidity of the ice, varying from always acidic in the Holocene to always alkaline in the cold periods. In the interstadials, the ice is close to neutral, with most of it acidic in larger interstadials, most of it alkaline in smaller ones, and rapid alternations within interstadials. It is not clear whether neutralization of individual acidic particles occurred in the atmosphere or whether acid and alkaline particles coexisted until deposition in the snowpack. The changes in acidity observed at GRIP apply at least to all of Greenland and probably to much of North America. There would have been ecological effects and important changes in the uptake of some chemicals onto ice. If acidic sulfate particles were neutralized and removed from the atmosphere, which remains uncertain, then there are atmospheric chemistry and radiative effects that require further investigation.

  16. Relationships Between Long-term Atmospheric Wet Deposition and Stream Chemistry in Mid-Appalachian Forest Catchments

    NASA Astrophysics Data System (ADS)

    DeWalle, D. R.; Boyer, E. W.; Buda, A. R.

    2014-12-01

    Improved understanding of the link between atmospheric deposition and surface water quality is critical to assessing the degree to which forested watersheds have recovered from acidification. This presentation draws upon long-term (1982-2013) atmospheric wet deposition and stream chemistry time series to study how changes in atmospheric chemical inputs have been propagated to stream waters. We used autocorrelation and lagged cross-correlation techniques to analyze monthly time series describing variations of chloride, sulfate and inorganic nitrogen concentrations for four pairs of stream/deposition monitoring sites. Autocorrelation analysis revealed that individual atmospheric input time series of sulfate and inorganic nitrogen were strongly seasonal, while chloride inputs exhibited little seasonality. Stream chemistry time series exhibited gradually declining autocorrelation trends with increasing lag times suggesting that atmospheric input signals were variably damped by the forest ecosystems . Lagged cross-correlation between raw atmospheric and stream chemistry time series indicated gradual decreases in correlation within superimposed regular annual cycles of correlation over 10- 15 years of lag time. Pre-whitening of each atmospheric and stream time series using regression or ARIMA models removed the influence of long-term trends, seasonal cycles and other factors and revealed occurrence of relatively few and highly variable lag times with significant correlations. While lagged cross-correlation of raw time series data provided some useful insights into the long-term trend and seasonal nature of the linkages between atmospheric deposition and stream chemistry, cross-correlation of shorter-term residual variations after prewhitening did not produce a consistent pattern of lag times with significant correlations in our monthly time series data.

  17. Equilibrium Chemistry of the Atmospheres of Hot Earth-like Exoplanets

    NASA Astrophysics Data System (ADS)

    Schaefer, Laura; Lodders, K.; Fegley, B.

    2010-10-01

    The Kepler and COROT missions and Earth-based observations have discovered putative rocky exoplanets and at least some of these are very hot because they orbit their stars at close distance, e.g., CoRot-7b. Here we discuss atmospheric chemistry for an Earth-like planet hot enough to vaporize its crust. We computed the chemical equilibrium composition of a system with elemental abundances of the terrestrial continental crust from 500 - 4000 K as a function of pressure from 10-6 to 10+2.5 bars. Calculations were done with a Gibbs energy minimization code. We will present results for the major volatile elements H, C, N, O, and S, and the lithophile elements Na, K, Fe, Si, Mg, Al, Ca, and Ti at a nominal pressure of 100 bars as a function of temperature. The major gases are H2O and CO2 at low temperatures, and SiO, O, H, and O2 at high temperatures. We also present condensation temperatures for major compounds as a function of pressure, which will be useful in determining cloud composition. These results should be useful in planning spectroscopic studies of the atmospheres of hot Earth-like exoplanets. This work was supported by the NSF Astronomy Program and the NASA Astrobiology Program.

  18. A ground support electronic interface for the ionospheric spectroscopy and atmospheric chemistry (ISAAC) ultraviolet spectrograph

    NASA Astrophysics Data System (ADS)

    Macquarrie, Jeffrey A.

    1994-12-01

    This thesis details the design and development of an electronic Ground Support Equipment (GSE) interface for the Naval Postgraduate School's (NPS) Ionospheric Spectroscopy and Atmospheric Chemistry (ISAAC) spectrograph. The ISAAC spectrograph, which was designed at NPS and built by Research Support Instruments, Inc., is intended to observe atmospheric airglow and auroral emissions in the ultraviolet (1800A to 3300A) wavelength region. It is to be included as one of several sensors flown onboard the Advanced Research and Global Observation Satellite (ARGOS), which is scheduled for an early 1996 launch. The GSE was developed in order to allow ground testing and calibration of the instrument prior to and during integration with the satellite bus. The GSE includes hardware to provide the connections between various components of the spectrograph and a Macintosh computer with an installed I/O card. The GSE also includes a user-friendly software interface written with LabVIEW 2.2 that provides the ability to view spectra obtained from the instrument and to remotely control mechanical functions of the spectrograph. An initial wavelength calibration of the spectrograph has been performed using the completed GSE.

  19. A black carbon emission data base for atmospheric chemistry and climate studies

    SciTech Connect

    Dignon, J.; Eddleman, H.E.; Penner, J.E.

    1994-10-01

    A global data base of black carbon emissions to the atmosphere from fossil fuel combustion has been compiled for the use in atmospheric chemistry and climate studies. The resolution provided is at 1{degree} latitude by 1{degree} longitude based on previous work by Matthews, Lemer et al., and Dignon. A more extensive description of the assumptions made and emission factors used in this data base can be found in Penner et al. The original work of Penner et al. provides the emissions inventory data on a 5{degree} by 5{degree} resolution. The units of emission for this updated version of the inventory yield a global total of 12.6 TgC/y and are given as the mass in metric tons of carbon for each 1{degree} x 1{degree} grid. It is important to note that this is not equivalent to a flux, in that the area of the grid boxes vary latitudinally. The emissions are expected to represent the emissions for a typical mid-1980s year. The distribution of emission is based on national totals and then mapped on to the 1{degree} x 1{degree} grid according to the updated population mapping of Logan. A description of this mapping procedure can be found in Dignon.

  20. Three infrared spectrometers, an atmospheric chemistry suite for the ExoMars 2016 trace gas orbiter

    NASA Astrophysics Data System (ADS)

    Korablev, Oleg; Trokhimovsky, Alexander; Grigoriev, Alexei V.; Shakun, Alexei; Ivanov, Yuriy S.; Moshkin, Boris; Anufreychik, Konstantin; Timonin, Denis; Dziuban, Ilia; Kalinnikov, Yurii K.; Montmessin, Franck

    2014-01-01

    The atmospheric chemistry suite (ACS) package is a part of the Russian contribution to the ExoMars ESA-Roscosmos mission. ACS consists of three separate infrared spectrometers, sharing common mechanical, electrical, and thermal interfaces. The near-infrared (NIR) channel is a versatile spectrometer for the spectral range of 0.7-1.6 μm with a resolving power of ˜20,000. The instrument employs the principle of an echelle spectrometer with an acousto-optical tunable filter (AOTF) as a preselector. NIR will be operated in nadir, in solar occultations, and possibly on the limb. Scientific targets of NIR are the measurements of water vapor, aerosols, and dayside or nightside airglows. The mid-infrared (MIR) channel is a cross-dispersion echelle instrument dedicated to solar occultation measurements in the range of 2.2-4.4 μm targeting the resolving power of 50,000. MIR is dedicated to sensitive measurements of trace gases. The thermal infrared channel (TIRVIM) is a 2-inch double pendulum Fourier-transform spectrometer for the spectral range of 1.7-17 μm with apodized resolution varying from 0.2 to 1.6 cm-1. TIRVIM is primarily dedicated to the monitoring of atmospheric temperatures and aerosol states in nadir. The present paper describes the concept of the instrument, and in more detail, the optical design and the expected parameters of its three parts channel by channel.

  1. Photon and Water Mediated Sulfur Oxide and Acid Chemistry in the Atmosphere of Venus

    NASA Astrophysics Data System (ADS)

    Kroll, Jay A.; Vaida, Veronica

    2014-06-01

    Sulfur compounds have been observed in the atmospheres of a number of planetary bodies in our solar system including Venus, Earth, Mars, Io, Europa, and Callisto. The global cloud cover on Venus located at an altitude between 50 and 80 kilometers is composed primarily of sulfuric acid (H_2SO_4) and water. Planetary photochemical models have attempted to explain observations of sulfuric acid and sulfur oxides with significant discrepancies remaining between models and observation. In particular, high SO_2 mixing ratios are observed above 90 km which exceed model predictions by orders of magnitude. Work recently done in the Vaida lab has shown red light can drive photochemistry through overtone pumping for acids like H_2SO_4 and has been successful in explaining much of the sulfur chemistry in Earth's atmosphere. Water can have a number of interesting effects such as catalysis, suppression, and anti-catalysis of thermal and photochemical processes. We investigate the role of water complexes in the hydration of sulfur oxides and dehydration of sulfur acids and present spectroscopic studies to document such effects. We investigate these reactions using FTIR and UV/Vis spectroscopy and will report on our findings.

  2. Vibrational Spectroscopy of Sodium Halide and Hydrogen Halide Aqueous Solutions: Application to Atmospheric Aerosol Chemistry

    NASA Astrophysics Data System (ADS)

    Levering, L. M.; Liu, D.; Allen, H. C.

    2003-12-01

    Heterogeneous reactions on the surfaces of atmospheric aerosols play an important role in atmospheric chemistry. These reactions are capable of converting alkyl and hydrogen halides (common constituents of marine boundary aerosols) into active halogen compounds. Fundamental questions still remain concerning surface species and reaction mechanisms pertaining to marine boundary aerosols. The first step in beginning to understand these heterogeneous reactions is to determine how ions in solution affect the structure of water at the interface. Vibrational sum frequency generation spectroscopy is used to examine the air-liquid interface of sodium halide and hydrogen halide (i.e. strong acid) solutions. In addition, comparison of the bulk water structure to that of the interface is accomplished using Raman spectroscopy. The hydrogen-bonding environment at the surface of NaCl is found to be similar to that of the air-water interface. In contrast, the interfacial water structure of NaBr, HCl, and HBr solutions is significantly altered from that of neat water. In the bulk, NaCl, NaBr, HCl, and HBr solutions disturb the hydrogen-bonding network of neat water. A comparison between the corresponding salts and acids show that the salts produce greater disorder (i.e. less coupling of the water symmetric stretching modes) in the bulk water structure.

  3. Biomass burning in the tropics: impact on atmospheric chemistry and biogeochemical cycles.

    PubMed

    Crutzen, P J; Andreae, M O

    1990-12-21

    Biomass burning is widespread, especially in the tropics. It serves to clear land for shifting cultivation, to convert forests to agricultural and pastoral lands, and to remove dry vegetation in order to promote agricultural productivity and the growth of higher yield grasses. Furthermore, much agricultural waste and fuel wood is being combusted, particularly in developing countries. Biomass containing 2 to 5 petagrams of carbon is burned annually (1 petagram = 10(15) grams), producing large amounts of trace gases and aerosol particles that play important roles in atmospheric chemistry and climate. Emissions of carbon monoxide and methane by biomass burning affect the oxidation efficiency of the atmosphere by reacting with hydroxyl radicals, and emissions of nitric oxide and hydrocarbons lead to high ozone concentrations in the tropics during the dry season. Large quantities of smoke particles are produced as well, and these can serve as cloud condensation nuclei. These particles may thus substantially influence cloud microphysical and optical properties, an effect that could have repercussions for the radiation budget and the hydrological cycle in the tropics. Widespread burning may also disturb biogeochemical cycles, especially that of nitrogen. About 50 percent of the nitrogen in the biomass fuel can be released as molecular nitrogen. This pyrdenitrification process causes a sizable loss of fixed nitrogen in tropical ecosystems, in the range of 10 to 20 teragrams per year (1 teragram = 10(12) grams). PMID:17734705

  4. Geochemical cycles of atmospheric gases

    NASA Technical Reports Server (NTRS)

    Walker, J. C. G.; Drever, J. I.

    1988-01-01

    The processes that control the atmosphere and atmospheric changes are reviewed. The geochemical cycles of water vapor, nitrogen, carbon dioxide, oxygen, and minor atmospheric constituents are examined. Changes in atmospheric chemistry with time are discussed using evidence from the rock record and analysis of the present atmosphere. The role of biological evolution in the history of the atmosphere and projected changes in the future atmosphere are considered.

  5. Upper Atmosphere Sounding Rocket Projects at Esrange Space Center

    NASA Astrophysics Data System (ADS)

    Lockowandt, Christian; Kemi, Stig; Sjolander, Krister; Abrahamsson, Mattias

    Swedish Space Corporation, SSC has a long tradition of developing and launching scientific sounding rockets from Esrange Space Center with the aim to study the different layers of the atmosphere and near space. Now a new era has started with an initiative from the Swedish National Space Board, SNSB. The sounding rocket and atmospheric balloon activities will be vitalised with a national program offering the scientific community yearly rocket launches and balloon flights. The three upcoming sounding rocket missions that have recently started are: O-STATES O STATES (Oxygen transformation in the thermosphere) is a research project at the Meteorological Institute of Stockholm University with Prof. Jörg Gumbel, as responsible researcher. The payload comprises two instrument modules with totally 7 instruments for studying oxygen in its various forms. The payload will be launched twice on two sounding rockets at the same launch campaign, in different atmospheric conditions. This provides a cost-effective mission with a large research exchange. The launches from Esrange Space Center are preliminary scheduled to take place in August 2014 with an apogee of approximately 250 km. SPIDER SPIDER (Small Payloads for Investigation of Disturbances in Electrojet by Rockets) is a research project at Space and Plasma Physics, Royal Institute of Technology, Stockholm with Nicholay Ivchenko as responsible researcher. The mission includes up to 10 subsidiary payloads ejected from the main payload to measure the structure of the electrostatic turbulence in the ionosphere. The measurements take place entirely in the subsidiary payloads, which are completely autonomous and recovered individually after the flight. The launch from Esrange Space Center is preliminary scheduled to take place in March 2015 with a desired apogee of approximately 140 km. LEEWAVES LEEWAVES (Local Excitation and Effects of Waves on Atmospheric Vertical Structure) is a research project at the Meteorological

  6. Clouds and Chemistry in the Atmosphere of Extrasolar Planet HR8799b

    SciTech Connect

    Barman, T S; Macintosh, B A; Konopacky, Q M; Marois, C

    2011-03-21

    Using the integral field spectrograph OSIRIS, on the Keck II telescope, broad near-infrared H and K-band spectra of the young exoplanet HR8799b have been obtained. In addition, six new narrow-band photometric measurements have been taken across the H and K bands. These data are combined with previously published photometry for an analysis of the planet's atmospheric properties. Thick photospheric dust cloud opacity is invoked to explain the planet's red near-IR colors and relatively smooth near-IR spectrum. Strong water absorption is detected, indicating a Hydrogen-rich atmosphere. Only weak CH{sub 4} absorption is detected at K band, indicating efficient vertical mixing and a disequilibrium CO/CH{sub 4} ratio at photospheric depths. The H-band spectrum has a distinct triangular shape consistent with low surface gravity. New giant planet atmosphere models are compared to these data with best fitting bulk parameters, T{sub eff} = 1100K {+-} 100 and log(g) = 3.5 {+-} 0.5 (for solar composition). Given the observed luminosity (log L{sub obs}/L{sub {circle_dot}} {approx} -5.1), these values correspond to a radius of 0.75 R{sub Jup{sub 0.12}{sup +0.17}} and mass {approx} 0.72 M{sub Jup{sub -0.6}{sup +2.6}} - strikingly inconsistent with interior/evolution models. Enhanced metallicity (up to {approx} 10 x that of the Sun) along with thick clouds and non-equilibrium chemistry are likely required to reproduce the complete ensemble of spectroscopic and photometric data and the low effective temperatures (< 1000K) required by the evolution models.

  7. Implementation of a convective atmospheric boundary layer scheme in a tropospheric chemistry transport model

    NASA Astrophysics Data System (ADS)

    Wang, K.-Y.; Pyle, J. A.; Sanderson, M. G.; Bridgeman, C.

    1999-10-01

    A convective atmospheric boundary layer (ABL) scheme for the transport of trace gases in the lower troposphere has been implemented from the Community Climate Model, Version 2 [Hack et al., 1993] into a tropospheric chemistry transport model [Wang, 1998]. The atmospheric boundary layer scheme includes the calculation of atmospheric radiative transfer, surface energy balance, and land surface temperature and has a specified annual variation of sea surface temperature. The calculated diurnal variation of the height of the boundary layer is similar to the results of Troen and Mahrt [1986] and is in a good agreement with Holtslag and Boville [1993]. The modeled height of the boundary layer shows a seasonal shift between land and sea in the Northern Hemisphere. In summer (June-July-August), the height of the boundary layer is deeper over land (850-2250 m) and shallower over sea (50-850 m); while in winter (December-January-February), it is shallower over land (50-850 m) and deeper over sea (850-2850 m). The coupled ABL-chemical transport model is verified against measurements of radon 222 and methane. Comparison of the coupled model with a non-ABL model indicates significant differences between these model simulations and a better agreement between the coupled model and measurements. There is a significant effect on the trace gas distribution when the ABL model is compared with the non-ABL schemes. For example, the ABL scheme shows more O3 transported from the middle troposphere down to the surface, while more CO is pumped up from the surface into the middle troposphere. The seasonal cycle of modeled CH4 is significantly improved with the inclusion of the new ABL scheme, especially in regions which are not remote from methane sources.

  8. A Simplified Model to Predict the Effect of Increasing Atmospheric CO[subscript 2] on Carbonate Chemistry in the Ocean

    ERIC Educational Resources Information Center

    Bozlee, Brian J.; Janebo, Maria; Jahn, Ginger

    2008-01-01

    The chemistry of dissolved inorganic carbon in seawater is reviewed and used to predict the potential effect of rising levels of carbon dioxide in the atmosphere. In agreement with more detailed treatments, we find that calcium carbonate (aragonite) may become unsaturated in cold surface seawater by the year 2100 C.E., resulting in the destruction…

  9. Project of the URAN array for registration of atmospheric neutrons

    NASA Astrophysics Data System (ADS)

    Gromushkin, D. M.; Barbashina, N. S.; Bogdanov, F. A.; Kokoulin, R. P.; Ovchinnikov, V. V.; Petrukhin, A. A.; Stenkin, Yu V.; Khokhlov, S. S.; Shulzhenko, I. A.; Yashin, I. I.

    2016-02-01

    The project of a new setup is directed at the registration of atmospheric neutrons (URAN) generated by hadronic component of extensive air showers (EAS). The setup includes 72 en-detector which simultaneously register two major EAS components: electromagnetic by the group passage of charged particles and hadron component by the thermal neutrons. The neutrons and charged particles are detected using a specialized scintillation composition made of granulated alloy of crystals based on the ZnS(Ag) powder with an admixture of B2O3.

  10. Programmatic mission capabilities - chemistry and metallurgy research replacement (CMRR) project

    SciTech Connect

    Gunderson, L Nguyen; Kornreich, Drew E; Wong, Amy S

    2011-01-04

    CMRR will have analysis capabilities that support all the nuclear-material programs and national security needs. CMRR will replace the aging CMR Building and provide a key component responsive infrastructure necessary to sustain all nuclear programs and the nuclear-weapons complex. Material characterization capabilities - evaluate the microstructures and properties of nuclear materials and provide experimental data to validate process and performance models. Analytical chemistry capabilities - provide expertise in chemical and radiochemical analysis of materials where actinide elements make up a significant portion of the sample.

  11. A new Geoengineering Model Intercomparison Project (GeoMIP) experiment designed for climate and chemistry models

    NASA Astrophysics Data System (ADS)

    Tilmes, S.; Mills, M. J.; Niemeier, U.; Schmidt, H.; Robock, A.; Kravitz, B.; Lamarque, J.-F.; Pitari, G.; English, J. M.

    2014-08-01

    A new Geoengineering Model Intercomparison Project (GeoMIP) experiment "G4 specified stratospheric aerosols" (short name: G4SSA) is proposed to investigate the impact of stratospheric aerosol geoengineering on atmospheric composition, climate, and the environment. In contrast to the earlier G4 GeoMIP experiment, which requires an emission of sulphur dioxide (SO2) into the model, a prescribed aerosol forcing file is provided to the community, to be consistently applied to future model experiments between 2020 and 2100. This stratospheric aerosol distribution, with a total burden of about 2 Tg S has been derived using the ECHAM5-HAM microphysical model, based on a continuous annual tropical emission of 8 Tg SO2 year-1. A ramp-up of geoengineering in 2020 and a ramp-down in 2070 over a period of two years are included in the distribution, while a background aerosol burden should be used for the last 3 decades of the experiment. The performance of this experiment using climate and chemistry models in a multi-model comparison framework will allow us to better understand the significance of the impact of geoengineering and the abrupt termination after 50 years on climate and composition of the atmosphere in a changing environment. The zonal and monthly mean stratospheric aerosol input dataset is available at https://www2.acd.ucar.edu/gcm/geomip-g4-specified-stratospheric-aerosol-data-set.

  12. Troposphere-Stratosphere Coupled Chemistry-Climate Interactions: From Global Warming Projections to Air Quality

    NASA Astrophysics Data System (ADS)

    Nowack, P. J.; Abraham, N. L.; Maycock, A. C.; Braesicke, P.; Pyle, J. A.

    2015-12-01

    Changes in stratospheric composition can affect tropospheric composition and vice versa. Of particular interest are trace gas concentrations at the interface between these two atmospheric layers in the tropical upper troposphere and lower stratosphere (UTLS). This is due to the crucial importance of composition changes in the UTLS for the global energy budget. In a recent study (Nowack et al., 2015), we provided further evidence that composition changes in the tropical UTLS can significantly affect global warming projections. Using a state-of-the-art atmosphere-ocean chemistry-climate model, we found a ~20% smaller global warming in response to an abrupt 4xCO2 forcing if composition feedbacks were included in the calculations as compared to simulations in which composition feedbacks were not considered. We attributed this large difference in surface warming mainly to circulation-driven decreases in tropical UTLS ozone and related changes in stratospheric water vapor, partly counteracted by simultaneous changes in ice clouds. Here, we explain why this result is expected to differ between models and how, inter alia, tropospheric chemical mechanisms can contribute to this uncertainty. We highlight that improving our understanding of processes in the tropical UTLS and their representation in Earth system models remains a key challenge in climate research.Finally, taking geoengineering as a new example, we show that changes in the stratosphere can have an impact on air quality in the troposphere. In particular, we explain for a simple solar radiation management scenario how changes in surface ozone can be linked to changes in meteorology and composition in the troposphere and stratosphere. In conclusion, we highlight the importance of considering air quality impacts when evaluating a variety of geoengineering scenarios. Reference: Nowack, P.J., Abraham, N.L., Maycock, A.C., Braesicke, P., Gregory, J.M., Joshi, M.M., Osprey, A., and Pyle, J.A. Nature Climate Change 5, 41

  13. MOUNTAIN CLOUD CHEMISTRY PROJECT WET, DRY ANDCLOUD WATER DEPOSITION

    EPA Science Inventory

    This report is the second in a series of annual summaries of research on the deposition of airborne chemicals to forest canopies and the forest floor in eastern North America. The report is based on observations and model estimates of atmospheric deposition at high elevation site...

  14. The Southern Tropical Atlantic Region Experiment (STARE): Transport and Atmospheric Chemistry near the Equator-Atlantic (TRACE A) and Southern African Fire-Atmosphere Research Initiative (SAFARI): An introduction

    NASA Astrophysics Data System (ADS)

    Andreae, Meinrat O.; Fishman, Jack; Lindesay, Janette

    1996-10-01

    In November 1988 some 50 atmospheric scientists met at Dookie College, a small campus in the agricultural lands of Victoria, Australia, to map out the scientific goals of the International Global Atmospheric Chemistry (IGAC) Program, which was to become one of the first operational Core Projects of the International Geosphere-Biosphere Program (IGBP). They identified the tropical regions as one of the priority areas for future international, coordinated research in atmospheric chemistry because of the vast biological activity in the tropics, with a correspondingly large potential for biogenic emissions, and the rapidly growing human populations and resulting land use change in these regions. In view of the prominent role that biomass burning plays in the tropics as a source of atmospheric pollutants and of the important ecological functions of vegetation fires in the tropics, the scientists at Dookie created the Biomass Burning Experiment (BIBEX) with the goals of characterizing the fluxes of gases and aerosols from biomass burning to the global atmosphere and assessing the consequences of pyrogenic emissions on chemical and physical climate. The southern tropical Atlantic region, defined here as the region containing the Amazon basin, the tropical South Atlantic, and southern Africa, was the obvious first focus of research for this project. Large tropical forest and savanna fires had been known to occur here every year. In addition, observations from satellites and from the space shuttle had shown high levels of tropospheric ozone and carbon monoxide to be present over this region every year in the August-to-October period. Results from previous campaigns (ABLE 2A, CITE 3, DECAFE 88) also suggested a widespread impact of vegetation fires on both continents on the trace gas and aerosol content of the troposphere in this region.

  15. Update of the Black Dog atmospheric fluidized bed combustion project

    SciTech Connect

    Osthus, D.; Larva, J.; Rens, D. )

    1988-01-01

    Northern States Power Co. converted its Black Dog Unit 2, a pulverized coal-fired 100 MW unit that was built in 1954, to an atmospheric fluidized bed (bubbling bed) configuration, in order to commercially demonstrate AFBC technology as a cost-effective way to reduce SO2 emissions. As part of the AFBC conversion, the unit was upgraded to 130 MW capacity. Unit 2 burns Western coal, is equipped with electrostatic precipitators, and cycles on and off line daily. The innovative nature of this project contributed to a protracted encountered. These problems are discussed. Many of the problems have been solved, and the unit is now meeting most of the goals set for the project.

  16. Russian contribution to ExoMars Trace Gas Orbiter: Atmospheric Chemistry Suite (ACS)

    NASA Astrophysics Data System (ADS)

    Shakun, Alexey; Korablev, Oleg; Trokhimovskiy, Alexander; Grigoriev, Alexey; Anufreychik, Konstantin; Fedorova, Anna; Ignatiev, Nikolay; Ivanov, Yuriy; Moshkin, Boris; Kalinnikov, Yuriy; Montmessin, Franck

    2016-04-01

    Atmospheric Chemistry Suite (ACS) is a part of science payload of Trace Gas Orbiter (TGO), ExoMars mission. This project developed by European Space Agency (ESA) in collaboration with Russian Space Agency (Roscosmos). Russian contribution to ExoMars TGO is the Proton rocket and two science instruments ACS (three infrared spectrometers) and FREND (neutron detector). ACS consists of three infrared spectrometers (ACS/NIR, ACS/MIR and ACS/TIRVIM) capable to take spectral measurements from near to thermal infrared range simultaneously or separately. Spectrometric channels of ACS share common mechanical, electrical, and thermal interfaces. Electronic box (ACS/BE) provides to spectrometric channels power and data transfer interfaces. SpaceWire link is used for science data transfer and MIL-1553 link - for commanding and housekeeping data transfer. The NIR channel is an echelle spectrometer with acousto-optic tunable filter (AOTF) for the selection of diffraction orders. ACS NIR is capable to perform nadir and occultation observations. NIR covers the spectral range of 0.7-1.7 μm with resolving power of ~25000. NIR will perform unique for TGO instruments nightglow science (searching for O2, OH, NO nightglow emissions on Mars). From the 1.38 μm band NIR will do water vapour mapping in nadir and H2O vertical profiling in solar occultations. High resolution NIR measurements of 1.27 μm O2(a1Δg) dayglow will supply indirect ozone observations on the dayside on nadir. In solar occultation mode, the O2 vertical profiles will be measured from the surface (in case of low dust activity) to the 40 km altitude based on 0.76 μm absorption band. Together with MIR channel in solar occultation NIR will support the measurements of CO2 density profiles (based on 1.43 μm band) and aerosols characterization from 0.7 to 4 μm. The wide spectral range will allow not just determine aerosol particle sizes and density at different altitudes, but also distinguish between dust and ice particles

  17. Investigation of Atmospheric Chemistry in the Tropical UTLS with NASA's Global Hawk UAS during ATTREX

    NASA Astrophysics Data System (ADS)

    Stutz, J.; Atlas, E. L.; Cheung, R.; Chipperfield, M.; Colosimo, S. F.; Deutschmann, T.; Daube, B. C.; Gao, R. S.; Elkins, J. W.; Fahey, D. W.; Feng, W.; Hossaini, R.; Navarro, M. A.; Pittman, J. V.; Raecke, R.; Scalone, L.; Spolaor, M.; Tricoli, U.; Thornberry, T. D.; Tsai, J. Y.; Werner, B.; Wofsy, S. C.; Pfeilsticker, K.

    2015-12-01

    Bromine species play an important role in ozone chemistry in the tropical upper troposphere / lower stratosphere (UTLS). The tropical UTLS also serves as a gate to the stratosphere, and the vertical transport of organic and inorganic bromine species is an important source of halogens that impact stratospheric ozone chemistry. An accurate quantification of the sources, sinks, and chemical transformation of bromine species is thus crucial to the understanding of the bromine and ozone budget in the UTLS and the stratosphere. However, the investigation of the composition of the tropical UTLS is challenging, as the altitude of this region of 15 - 20 km requires high-altitude aircraft, or balloons. In recent years a new aircraft has become available to penetrate into this region: NASA's Global Hawk (GH) Unmanned Aircraft System (UAS). The GH has a ceiling altitude of 20 km and a 24h endurance with a full complement of scientific experiments. The GH provides a new and exciting platform that allows unique insights into atmospheric processes in the UTLS. Here we present observations of CH4, BrO, NO2, and ozone made on-board the GH during the 2011, 2013, and 2014 Airborne Tropical TRopopause EXperiment (ATTREX) in the pacific tropical UTLS. We will discuss the details of UV-vis remote sensing measurements of BrO and NO2 by the UCLA/HD limb scanning Differential Optical Absorption Spectroscopy instrument. We also present observations of organic bromine species from the University of Miami's Whole Air Sampler, in-situ ozone measurement by NOAA, and CH4 measurements by the Harvard Picarro instrument and the NOAA UCATS gas chromatograph. Methods to determine vertical trace gas profiles through aircraft maneuvers and by scanning the mini-DOAS telescope in viewing elevation will be discussed. The combination of the observations with calculations using the TOMCAT/SLIMCAT 3-D model allows quantification and interpretation of the bromine and ozone budget in the UTLS.

  18. Global atmospheric sulfur budget under volcanically quiescent conditions: Aerosol-chemistry-climate model predictions and validation

    NASA Astrophysics Data System (ADS)

    Sheng, Jian-Xiong; Weisenstein, Debra K.; Luo, Bei-Ping; Rozanov, Eugene; Stenke, Andrea; Anet, Julien; Bingemer, Heinz; Peter, Thomas

    2015-01-01

    The global atmospheric sulfur budget and its emission dependence have been investigated using the coupled aerosol-chemistry-climate model SOCOL-AER. The aerosol module comprises gaseous and aqueous sulfur chemistry and comprehensive microphysics. The particle distribution is resolved by 40 size bins spanning radii from 0.39 nm to 3.2 μm, including size-dependent particle composition. Aerosol radiative properties required by the climate model are calculated online from the aerosol module. The model successfully reproduces main features of stratospheric aerosols under nonvolcanic conditions, including aerosol extinctions compared to Stratospheric Aerosol and Gas Experiment II (SAGE II) and Halogen Occultation Experiment, and size distributions compared to in situ measurements. The calculated stratospheric aerosol burden is 109 Gg of sulfur, matching the SAGE II-based estimate (112 Gg). In terms of fluxes through the tropopause, the stratospheric aerosol layer is due to about 43% primary tropospheric aerosol, 28% SO2, 23% carbonyl sulfide (OCS), 4% H2S, and 2% dimethyl sulfide (DMS). Turning off emissions of the short-lived species SO2, H2S, and DMS shows that OCS alone still establishes about 56% of the original stratospheric aerosol burden. Further sensitivity simulations reveal that anticipated increases in anthropogenic SO2 emissions in China and India have a larger influence on stratospheric aerosols than the same increase in Western Europe or the U.S., due to deep convection in the western Pacific region. However, even a doubling of Chinese and Indian emissions is predicted to increase the stratospheric background aerosol burden only by 9%. In contrast, small to moderate volcanic eruptions, such as that of Nabro in 2011, may easily double the stratospheric aerosol loading.

  19. A review of the sources of uncertainties in atmospheric mercury modeling II. Mercury surface and heterogeneous chemistry - A missing link

    NASA Astrophysics Data System (ADS)

    Subir, Mahamud; Ariya, Parisa A.; Dastoor, Ashu P.

    2012-01-01

    Despite direct and indirect evidence suggesting that heterogeneous surfaces potentially play a key role in mercury chemistry, there is little known about mercury reactions and equilibrium processes that take place at atmospherically relevant surfaces. The lack of knowledge of mercury surface chemistry is a major gap for adequate modeling of mercury cycling. In part I of this review, we assessed the sources of uncertainty associated with existing kinetic parameters. In this part, we present evidence that supports surface-mercury interactions in the ecosystem elucidating the importance of heterogeneous and interfacial chemistry from a fundamental viewpoint. Consequently, we draw attention to the chemical processes that are missing and/or are inadequately incorporated in the atmospheric mercury models and highlight some of the recent advances in this field. We reveal that adsorption equilibrium of mercury species, most of which are not well characterized, to natural surfaces such as atmospheric particles and air/water interface are not known. Gas-liquid partitioning of mercury and its compounds are not adequately implemented. Equilibrium constants for aqueous phase complex formation with dissolved organic matters and formation of possible solid mercury clusters and nanoparticles are not considered in the global models. Potential heterogeneous mercury reduction reactions that can be important in mercury cycling require further evaluation which includes characterizing the influence of surfaces on mercury chemistry. The implementation of chemical processes for which information is available but not currently included in the models bears the potential of greatly reducing the uncertainties that are currently present in the models.

  20. Current Status of the Validation of the Atmospheric Chemistry Instruments on Envisat

    NASA Astrophysics Data System (ADS)

    Lecomte, P.; Koopman, R.; Zehner, C.; Laur, H.; Attema, E.; Wursteisen, P.; Snoeij, P.

    2003-04-01

    Envisat is ESA's advanced Earth observing satellite launched in March 2002 and is designed to provide measurements of the atmosphere, ocean, land and ice over a five-year period. After the launch and the switch-on period, a six-month commissioning phase has taken place for instrument calibration and geophysical validation, concluded with the Envisat Calibration Review held in September 2002. In addition to ESA and its industrial partners in the Envisat consortium, many other companies and research institutes have contributed to the calibration and validation programme under ESA contract as expert support laboratories (ESLs). A major contribution has also been made by the Principal Investigators of approved proposals submitted to ESA in response to a worldwide "Announcement of Opportunity for the Exploitation of the Envisat Data Products" in 1998. Working teams have been formed in which the different participants worked side by side to achieve the objectives of the calibration and validation programme. Validation is a comparison of Envisat level-2 data products and estimates of the different geophysical variables obtained by independent means, the validation instruments. Validation is closely linked to calibration because inconsistencies discovered in the comparison of Envisat Level 2 data products to well-known external instruments can have many different sources, including inaccuracies of the Envisat instrument calibration and the data calibration algorithms. Therefore, initial validation of the geophysical variables has provided feedback to calibration, de-bugging and algorithm improvement. The initial validation phase ended in December 2002 with the Envisat Validation Workshop at which, for a number of products, a final quality statement was given. Full validation of all data products available from the Atmospheric Chemistry Instruments on Envisat (MIPAS, GOMOS and SCIAMACHY) is quite a challenge and therefore it has been decided to adopt a step-wise approach

  1. Simulation of a Forensic Chemistry Problem: A Multidisciplinary Project for Secondary School Chemistry Students.

    ERIC Educational Resources Information Center

    Long, G. A.

    1995-01-01

    Describes a project that uses a multidisciplinary approach to problem solving in analyzing a crime scene and suspect evidence. Requires each student to work effectively in a team, communicate in both written and oral forms, perform hands-on laboratory manipulations, and realize that the entire class was depending on their individual contributions…

  2. Net throughfall chemistry and atmospheric deposition at two forests of different elevations

    SciTech Connect

    Schaefer, D.A.; Lindberg, S.E.

    1987-07-01

    We are measuring atmospheric deposition and throughfall chemistry at two coniferous sites. The higher (1800m) site is a red spruce (Picea rubens) forest; the lower (300m) is a loblolly pine (Pinus taeda) forest. Summed net chemical fluxes in throughfall (calculated as throughfall depth X concentrations minus rain depth X concentrations) are compared for April through July. Net fluxes of SO/sub 4//sup 2-/, NO/sub 3//sup -/, Na/sup +/, and Cl/sup -/, in throughfall are greater at the spruce site. Net fluxes of K/sup +/ and NH/sub 4//sup +/ in throughfall are greater at the pine site. Net fluxes of Ca/sub 2//sup +/ and Mg/sub 2//sup +4/ are nearly equal. Air concentrations and surrogate surface fluxes are quite similar between sites, except for higher NO/sub 3//sup -/ particle flux at the spruce site. Greater net throughfall fluxes at the spruce site reflect both greater canopy surface area, and cloud deposition to this site. Greater net K/sup +/ flux at the pine site reflects canopy losses. Negative NH/sub 4//sup +/ flux indicates spruce canopy uptake.

  3. Evaluation of NO+ reagent ion chemistry for online measurements of atmospheric volatile organic compounds

    NASA Astrophysics Data System (ADS)

    Koss, Abigail R.; Warneke, Carsten; Yuan, Bin; Coggon, Matthew M.; Veres, Patrick R.; de Gouw, Joost A.

    2016-07-01

    NO+ chemical ionization mass spectrometry (NO+ CIMS) can achieve fast (1 Hz and faster) online measurement of trace atmospheric volatile organic compounds (VOCs) that cannot be ionized with H3O+ ions (e.g., in a PTR-MS or H3O+ CIMS instrument). Here we describe the adaptation of a high-resolution time-of-flight H3O+ CIMS instrument to use NO+ primary ion chemistry. We evaluate the NO+ technique with respect to compound specificity, sensitivity, and VOC species measured compared to H3O+. The evaluation is established by a series of experiments including laboratory investigation using a gas-chromatography (GC) interface, in situ measurement of urban air using a GC interface, and direct in situ measurement of urban air. The main findings are that (1) NO+ is useful for isomerically resolved measurements of carbonyl species; (2) NO+ can achieve sensitive detection of small (C4-C8) branched alkanes but is not unambiguous for most; and (3) compound-specific measurement of some alkanes, especially isopentane, methylpentane, and high-mass (C12-C15) n-alkanes, is possible with NO+. We also demonstrate fast in situ chemically specific measurements of C12 to C15 alkanes in ambient air.

  4. Laser flash photolysis studies of atmospheric free radical chemistry using optical diagnostic techniques

    NASA Technical Reports Server (NTRS)

    Wine, Paul H.; Nicovich, J. M.; Hynes, Anthony J.; Stickel, Robert E.; Thorn, R. P.; Chin, Mian; Cronkhite, Jeffrey A.; Shackelford, Christie J.; Zhao, Zhizhong; Daykin, Edward P.

    1993-01-01

    Some recent studies carried out in our laboratory are described where laser flash photolytic production of reactant free radicals has been combined with reactant and/or product detection using time-resolved optical techniques to investigate the kinetics and mechanisms of important atmospheric chemical reactions. Discussed are (1) a study of the radical-radical reaction O + BrO yields Br + O2 where two photolysis lasers are employed to prepare the reaction mixture and where the reactants O and BrO are monitored simultaneously using atomic resonance fluorescence to detect O and multipass UV absorption to detect BrO; (2) a study of the reaction of atomic chlorine with dimethylsulfide (CH3SCH3) where atomic resonance fluorescence detection of Cl is employed to elucidate the kinetics and tunable diode laser absorption spectroscopy is employed to investigate the HCl product yield; and (3) a study of the aqueous phase chemistry of Cl2(-) radicals where longpath UV absorption spectroscopy is employed to investigate the kinetics of the Cl2(-) + H2O reaction.

  5. Numerical Simulations and Diagnostic Studies Relating Meteorology To Atmospheric Chemistry during TRACE-P

    NASA Technical Reports Server (NTRS)

    Fuelberg, Henry E.

    2003-01-01

    The Florida State University (FSU) team participated extensively in the pre-mission planning for TRACE-P through meetings, telephone calls, and e-mails. During Spring 2001, Prof. Fuelberg served as DC-8 Mission Meteorologist during the field campaign. He prepared meteorological guidance for each flight of the DC-8 and flew on each mission. After the field phase, FSU prepared various meteorological products, included backward air trajectories, for each flight of the DC-8 and P-3B. These were posted on the FSU and NASA-GTE web sites for use by all the Science Team. During the two-year post mission period, FSU conducted research relating meteorology to atmospheric chemistry during TRACE-P. This led to three journal articles in the Journal of Geophysical Research. FSU personnel were the lead authors on each of these articles. Abstracts of these articles are attached. In addition, the FSU team collaborated with other members of the TRACE-P Science Team to incorporate meteorological factors into their research. A list of publications resulting from these interactions is included.

  6. Laboratory studies of low temperature rate coefficients: The atmospheric chemistry of the outer planets

    NASA Technical Reports Server (NTRS)

    Leone, Stephen R.

    1995-01-01

    The objectives of the research are to measure low temperature laboratory rate coefficients for key reactions relevant to the atmospheres of Titan and Saturn. These reactions are, for example, C2H + H2, CH4, C2H2, and other hydrocarbons which need to be measured at low temperatures, down to approximately 150 K. The results of this work are provided to NASA specialists who study modeling of the hydrocarbon chemistry of the outer planets. The apparatus for this work consists of a pulsed laser photolysis system and a tunable F-center probe laser to monitor the disappearance of C2H. A low temperature cell with a cryogenic circulating fluid in the outer jacket provides the gas handling system for this work. These elements have been described in detail in previous reports. Several new results are completed and the publications are just being prepared. The reaction of C2H with C2H2 has been measured with an improved apparatus down to 154 K. An Arrhenius plot indicates a clear increase in the rate coefficient at the lowest temperatures, most likely because of the long-lived (C4H3) intermediate. The capability to achieve the lowest temperatures in this work was made possible by construction of a new cell and addition of a multipass arrangement for the probe laser, as well as improvements to the laser system.

  7. Impact of continental outflow on chemistry of atmospheric aerosols over tropical Bay of Bengal

    NASA Astrophysics Data System (ADS)

    Srinivas, B.; Kumar, A.; Sarin, M. M.; Sudheer, A. K.

    2011-07-01

    The continental outflow from Indo-Gangetic Plain and south-east Asia dominates the widespread dispersal of pollutants over tropical Bay of Bengal (BoB) during the late NE-monsoon (January-March). It is thus pertinent to assess the impact on marine atmospheric boundary layer of BoB. The chemical data, based on analyses of size-segregated (PM2.5 and PM10) aerosols, suggest the dominance of nss-SO42- (range: 1.3 to 28 μg m-3) in PM2.5. Almost all SO42- is of anthropogenic origin and accounts for as much as 65 % of the water-soluble inorganic constituents. The impact of anthropogenic sources is further evident from the widespread depletion of chloride (range: 40 to 100 %) compared to sea-salt composition. The carbonaceous species (EC and OC) contribute nearly 25 % to PM2.5; and significant linear relationship with K+ suggests biomass burning as their dominant source (biofuels and agricultural waste). The enhancement in the fractional solubility of aerosol Fe, as assessed in PM2.5, re-emphasizes the impact of combustion sources (biomass and fossil-fuel) and chemical processing (of dust) during the long-range transport. The high enrichment factors of heavy metals (Pb and Cd) further demonstrate the influence of pollution sources on the chemistry of MABL. The downwind transport of pollutants and exchange across air-sea interface can, thus, have profound impact on the ocean surface biogeochemistry.

  8. A short overview of the microbial population in clouds: Potential roles in atmospheric chemistry and nucleation processes

    NASA Astrophysics Data System (ADS)

    Delort, Anne-Marie; Vaïtilingom, Mickael; Amato, Pierre; Sancelme, Martine; Parazols, Marius; Mailhot, Gilles; Laj, Paolo; Deguillaume, Laurent

    2010-11-01

    Recent studies showed that living microorganisms, including bacteria, fungi and yeasts, are present in the atmospheric water phase (fog and clouds) and their role in chemical processes may have been underestimated. At the interface between atmospheric science and microbiology, information about this field of science suffers from the fact that not all recent findings are efficiently conveyed to both scientific communities. The purpose of this paper is therefore to provide a short overview of recent work linked to living organisms in the atmospheric water phase, from their activation to cloud droplets and ice crystal, to their potential impact on atmospheric chemical processes. This paper is focused on the microorganisms present in clouds and on the role they could play in atmospheric chemistry and nucleation processes. First, the life cycle of microorganisms via the atmosphere is examined, including their aerosolization from sources, their integration into clouds and their wet deposition on the ground. Second, special attention is paid to the possible impacts of microorganisms on liquid and ice nucleation processes. Third, a short description of the microorganisms that have been found in clouds and their variability in numbers and diversity is presented, emphasizing some specific characteristics that could favour their occurrence in cloud droplets. In the last section, the potential role of microbial activity as an alternative route to photochemical reaction pathways in cloud chemistry is discussed.

  9. Connecting biology and organic chemistry introductory laboratory courses through a collaborative research project.

    PubMed

    Boltax, Ariana L; Armanious, Stephanie; Kosinski-Collins, Melissa S; Pontrello, Jason K

    2015-01-01

    Modern research often requires collaboration of experts in fields, such as math, chemistry, biology, physics, and computer science to develop unique solutions to common problems. Traditional introductory undergraduate laboratory curricula in the sciences often do not emphasize connections possible between the various disciplines. We designed an interdisciplinary, medically relevant, project intended to help students see connections between chemistry and biology. Second term organic chemistry laboratory students designed and synthesized potential polymer inhibitors or inducers of polyglutamine protein aggregation. The use of novel target compounds added the uncertainty of scientific research to the project. Biology laboratory students then tested the novel potential pharmaceuticals in Huntington's disease model assays, using in vitro polyglutamine peptide aggregation and in vivo lethality studies in Drosophila. Students read articles from the primary literature describing the system from both chemical and biological perspectives. Assessment revealed that students emerged from both courses with a deeper understanding of the interdisciplinary nature of biology and chemistry and a heightened interest in basic research. The design of this collaborative project for introductory biology and organic chemistry labs demonstrated how the local interests and expertise at a university can be drawn from to create an effective way to integrate these introductory courses. Rather than simply presenting a series of experiments to be replicated, we hope that our efforts will inspire other scientists to think about how some aspect of authentic work can be brought into their own courses, and we also welcome additional collaborations to extend the scope of the scientific exploration. PMID:26148149

  10. Physics and chemistry of non-equilibrium, atmospheric pressure plasmas containing fluorine

    NASA Astrophysics Data System (ADS)

    Yang, Xiawan

    The physics and chemistry of low temperature, atmospheric pressure plasmas containing fluorine have been investigated with current, voltage, and power measurements, infrared absorption spectroscopy, and optical emission spectroscopy. The plasma source consisted of two closely spaced metal electrodes, supplied with radio-frequency power at 13.56 MHz. The fluorine atom concentration was measured in the downstream region of a carbon tetrafluoride and helium plasma using infrared spectroscopy. The gas discharge generated 1.2 x 10 15 cm-3 of F atoms, which is ˜100 times higher than that found in low-pressure plasmas. A numerical model of the plasma indicated that most of the F atoms were generated by the reaction of CF4 with metastable helium atoms. It was discovered that the atmospheric pressure, radio-frequency plasma could be made to undergo sheath breakdown with conversion from an alpha- to a gamma-mode discharge. With 0.4 vol% nitrogen in helium, this transition was accompanied by a 40% drop in voltage, a 12% decrease in current, and a surge in power density from 25 to 2083 W/cm3. The shift in intense plasma emission from the bulk gas to the surface of the electrodes was documented by optical techniques. When the plasma was operated in the alpha and gamma modes, 5.2% and 15.2% of the N2 was dissociated into atoms, respectively. In the latter case, the low dissociation efficiency was ascribed to the nonuniform structure of the plasma across the gap. In plasmas containing 1.0 vol% carbon tetrafluoride and sulfur hexafluoride, the alpha to gamma transition occurred smoothly with no discharge contraction. The electron density in these plasmas equaled 6.0 x 1011 cm-3, compared to 1.9 x 1013 cm -3 in pure helium. The drop in plasma density was due to fast electron attachment processes caused by the electronegative molecules, which also resulted in a high density of negative ions, up to 1013 cm-3. In addition, the non-equilibrium, atmospheric pressure plasma was used to

  11. Nucla circulating atmospheric fluidized bed demonstration project. Final report

    SciTech Connect

    Not Available

    1991-10-01

    Colorado-Ute Electric Association began a study to evaluate options for upgrading and extending the life of its Nucla power station in 1982. Located in southwestern Colorado near the town of Nucla, this station was commissioned in 1959 with a local bituminous coal as its design fuel for three identical stoker-fired units, each rated at 12.6 MW(e). Poor station efficiency, high fuel costs, and spiraling boiler maintenance costs forced the Nucla Station into low priority in the CUEA dispatch order as early as 1981. Among the options CUEA considered was to serve as a host utility to demonstrate Atmospheric Fluidized Bed Combustion (AFBC) technology. The anticipated environmental benefits and apparent attractive economics of a circulating AFBC led to Colorado-Ute`s decision to proceed with the design and construction of a demonstration project in 1984 at the Nucla facility.

  12. Independent Research Projects in General Chemistry Classes as an Introduction to Peer-Reviewed Literature

    ERIC Educational Resources Information Center

    Tribe, Lorena; Cooper, Evan L.

    2008-01-01

    A well-structured independent literature research project with a poster session was used to introduce students to peer-reviewed literature in a general chemistry course. Overall, students reported an enhanced appreciation of the course due to performing research at some level, using peer-reviewed literature, and presenting their results in a…

  13. s-Block Elements. Independent Learning Project for Advanced Chemistry (ILPAC). Unit I1.

    ERIC Educational Resources Information Center

    Inner London Education Authority (England).

    This unit is one of 10 first year units produced by the Independent Learning Project for Advanced Chemistry (ILPAC). The unit, which consists of two sections and an appendix, focuses on the elements and compounds of Groups I and II (the s-block) of the periodic table. The groups are treated concurrently to note comparisons between groups and to…

  14. Hydrocarbons. Independent Learning Project for Advanced Chemistry (ILPAC). Unit O1.

    ERIC Educational Resources Information Center

    Inner London Education Authority (England).

    This unit on hydrocarbons is one of 10 first year units produced by the Independent Learning Project for Advanced Chemistry (ILPAC). The unit is divided into sections dealing with alkanes, alkenes, alkynes, arenes, and several aspects of the petroleum industry. Two experiments, exercises (with answers), and pre- and post-tests are included.…

  15. Exploration of SO[subscript 2] Scrubbers: An Environmental Chemistry Project

    ERIC Educational Resources Information Center

    Schilling, Amber L.; Leber, Phyllis A.; Yoder, Claude H.

    2009-01-01

    The remediation of acid rain by SO[subscript 2] scrubbing is integrated into a laboratory project appropriate for first-year chemistry students. By burning a small amount of sulfur and bubbling the gas produced through distilled water, the student first observes one of the reactions that produces acid rain. The student then tests four different…

  16. Equilibrium I: Principles. Independent Learning Project for Advanced Chemistry (ILPAC). Unit P2.

    ERIC Educational Resources Information Center

    Inner London Education Authority (England).

    This unit on the principles of equilibrium is one of 10 first year units produced by the Independent Learning Project for Advanced Chemistry (ILPAC). The unit consists of two levels. After a treatment of non-mathematical aspects in level one (the idea of a reversible reaction, characteristics of an equilibrium state, the Le Chatelier's principle),…

  17. A Service-Learning Project in Chemistry: Environmental Monitoring of a Nature Preserve

    ERIC Educational Resources Information Center

    Kammler, David C.; Truong, Triet M.; VanNess, Garrett; McGowin, Audrey E.

    2012-01-01

    A collaborative environmental service-learning project was implemented between upper-level undergraduate science majors and graduate chemistry students at a large state school and first-year students at a small private liberal arts college. Students analyzed the water quality in a nature preserve by determining the quantities of 12 trace metals,…

  18. Undergraduate Introductory Quantitative Chemistry Laboratory Course: Interdisciplinary Group Projects in Phytoremediation

    ERIC Educational Resources Information Center

    Van Engelen, Debra L.; Suljak, Steven W.; Hall, J. Patrick; Holmes, Bert E.

    2007-01-01

    The laboratory course around the phytoremediation is designed to develop both individual skills and promote cooperative learning while starting students work on projects in a specific area of environmental chemistry and analysis. Many research-active undergraduate institutions have developed courses, which are interdisciplinary in nature that…

  19. Chemistry Laboratory--A Self-Paced Project Approach with Traditional Experiments.

    ERIC Educational Resources Information Center

    Faber, Gary C.; Martin, Elizabeth M.

    1983-01-01

    Citing problems with a traditional introductory chemistry laboratory program, discusses a two-semester, project-oriented laboratory program using traditional experiments. A series of slide/tape programs discussing/illustrating potentially difficult concepts and techniques is used to facilitate instruction. Includes list of topics covered in the…

  20. A Wiki-Based Group Project in an Inorganic Chemistry Foundation Course

    ERIC Educational Resources Information Center

    Kristian, Kathleen E.

    2015-01-01

    A semester-long group project that utilizes wiki sites to enhance collaboration was developed for a foundation course in inorganic chemistry. Through structured assignments, student groups use metal-based or metal-combating therapeutic agents as a model for applying and understanding course concepts; they also gain proficiency with scientific- and…

  1. Enhancing Undergraduate Students' Chemistry Understanding through Project-Based Learning in an IT Environment

    ERIC Educational Resources Information Center

    Barak, Miri; Dori, Yehudit Judy

    2005-01-01

    Project-based learning (PBL), which is increasingly supported by information technologies (IT), contributes to fostering student-directed scientific inquiry of problems in a real-world setting. This study investigated the integration of PBL in an IT environment into three undergraduate chemistry courses, each including both experimental and…

  2. Integrating Project-Based Service-Learning into an Advanced Environmental Chemistry Course

    ERIC Educational Resources Information Center

    Draper, Alison J.

    2004-01-01

    An active service-learning research work is conducted in the field of advanced environmental chemistry. Multiple projects are assigned to students, which promote individual learning skills, self-confidence as scientists, and a deep understanding of the environmental chemist's profession.

  3. The Halogens. Independent Learning Project for Advanced Chemistry (ILPAC). Unit I2.

    ERIC Educational Resources Information Center

    Inner London Education Authority (England).

    This unit is one of 10 first year units produced by the Independent Learning Project for Advanced Chemistry (ILPAC). The unit, which consists of two levels, focuses on the elements and compounds of Group IV (halogens) of the periodic table. Level one deals with the physical and chemical properties of the individual elements. Level two considers…

  4. Atomic Structure. Independent Learning Project for Advanced Chemistry (ILPAC). Unit S2.

    ERIC Educational Resources Information Center

    Inner London Education Authority (England).

    This unit on atomic structure is one of 10 first year units produced by the Independent Learning Project for Advanced Chemistry (ILPAC). The unit consists of two levels. Level one focuses on the atomic nucleus. Level two focuses on the arrangement of extranuclear electrons, approaching atomic orbitals through both electron bombardment and spectra.…

  5. The Mole. Independent Learning Project for Advanced Chemistry (ILPAC). Unit S1.

    ERIC Educational Resources Information Center

    Inner London Education Authority (England).

    This unit on the mole is one of 10 first year units produced by the Independent Learning Project for Advanced Chemistry (ILPAC). The unit, designed to help students consolidate some of the ideas about the mole learned in previous courses, consists of two levels. The first level focuses on: (1) relative mass; (2) the concept of the mole as the unit…

  6. Chemical Energetics. Independent Learning Project for Advanced Chemistry (ILPAC). Unit S3.

    ERIC Educational Resources Information Center

    Inner London Education Authority (England).

    This unit on chemical energetics is one of 10 first year units produced by the Independent Learning Project for Advanced Chemistry (ILPAC). The unit, which consists of two levels, provides a clear yet detailed and thorough introduction to the topic. Level one extends ideas from previous courses, introduces and emphasizes the importance of Hess'…

  7. The Gaseous State. Independent Learning Project for Advanced Chemistry (ILPAC). Unit P1.

    ERIC Educational Resources Information Center

    Inner London Education Authority (England).

    This unit on the gaseous state is one of 10 first year units produced by the Independent Learning Project for Advanced Chemistry (ILPAC). The unit consists of two levels. Level one deals with the distinctive characteristics of gases, then considers the gas laws, in particular the ideal gas equation and its applications. Level two concentrates on…

  8. Projects that Assist with Content in a Traditional Organic Chemistry Course

    ERIC Educational Resources Information Center

    Esteb, John J.; Magers, John R.; McNulty, LuAnne; Wilson, Anne M.

    2006-01-01

    Two projects, the reaction notebook and the end-of-semester synthesis activity are described which could help students to adopt a discovery-based learning and engage students in practical applications of chemistry. Students have provided positive feedback on this classroom assignment and have felt that it has helped them crystallize their thought…

  9. Bonding and Structure. Independent Learning Project for Advanced Chemistry (ILPAC). Unit S4.

    ERIC Educational Resources Information Center

    Inner London Education Authority (England).

    This unit on chemical bonding is one of 10 first year units produced by the Independent Learning Project for Advanced Chemistry (ILPAC). The unit, which consists of two levels, provides an introduction to the main types of chemical bonding and important aspects of structure. The main emphasis is placed on such topics as ionic and covalent bonding,…

  10. Equilibrium II: Acids and Bases. Independent Learning Project for Advanced Chemistry (ILPAC). Unit P3.

    ERIC Educational Resources Information Center

    Inner London Education Authority (England).

    This unit on equilibrium is one of 10 first year units produced by the Independent Learning Project for Advanced Chemistry (ILPAC). The unit, which consists of two levels, focuses on the application of equilibrium principles to equilibria involving weak acids and bases, including buffer solutions and indicators. Level one uses Le Chatelier's…

  11. A Transition from a Traditional to a Project-Like Physical Chemistry Laboratory via a Heterogeneous Catalysis Study.

    ERIC Educational Resources Information Center

    Goldwasser, M. R.; Leal, O.

    1979-01-01

    Outlines an approach for instruction in a physical chemistry laboratory which combines traditional and project-like experiments. An outline of laboratory experiments and examples of project-like experiments are included. (BT)

  12. Mathematical Modeling of Complex Reaction Systems for Computer-Aided Control and its Illustration on Atmospheric Chemistry

    NASA Astrophysics Data System (ADS)

    Amiryan, A.

    2015-12-01

    Modeling of sequential process has its own importance in Atmospheric Chemistry. Numerical calculations which allow to predict separate stages and components of chemical reaction make possible the reaction management, such is the new and perspective direction in chemical researches. Chemical processes basically pass multiple simple stages where various atoms and radicals participate. The complex chain of chemical reactionary systems complicates their research and the research is impossible without new methods of mathematical simulation and high technologies which allow not only to explain results of experiments but also to predict dynamics of processes. A new program package is suggested for solving research problems of chemical kinetics. The program is tested on different illustrative examples on Atmospheric Chemistry and installed in various scientific and educational institutions.

  13. Impact of Improvements in Volcanic Implementation on Atmospheric Chemistry and Climate in the GISS-E2 Model

    NASA Technical Reports Server (NTRS)

    Tsigaridis, Kostas; LeGrande, Allegra; Bauer, Susanne

    2015-01-01

    The representation of volcanic eruptions in climate models introduces some of the largest errors when evaluating historical simulations, partly due to the crude model parameterizations. We will show preliminary results from the Goddard Institute for Space Studies (GISS)-E2 model comparing traditional highly parameterized volcanic implementation (specified Aerosol Optical Depth, Effective Radius) to deploying the full aerosol microphysics module MATRIX and directly emitting SO2 allowing us the prognosically determine the chemistry and climate impact. We show a reasonable match in aerosol optical depth, effective radius, and forcing between the full aerosol implementation and reconstructions/observations of the Mt. Pinatubo 1991 eruption, with a few areas as targets for future improvement. This allows us to investigate not only the climate impact of the injection of volcanic aerosols, but also influences on regional water vapor, O3, and OH distributions. With the skill of the MATRIX volcano implementation established, we explore (1) how the height of the injection column of SO2 influence atmospheric chemistry and climate response, (2) how the initial condition of the atmosphere influences the climate and chemistry impact of the eruption with a particular focus on how ENSO and QBO and (3) how the coupled chemistry could mitigate the climate signal for much larger eruptions (i.e. the 1258 eruption, reconstructed to be approximately 10x Pinatubo). During each sensitivity experiment we assess the impact on profiles of water vapor, O3, and OH, and assess how the eruption impacts the budget of each.

  14. Impact of improvements in volcanic implementation on atmospheric chemistry and climate in the GISS-E2 Model

    NASA Astrophysics Data System (ADS)

    Tsigaridis, Kostas; LeGrande, Allegra; Bauer, Susanne

    2015-04-01

    The representation of volcanic eruptions in climate models introduces some of the largest errors when evaluating historical simulations, partly due to the crude model parameterizations. We will show preliminary results from the Goddard Institute for Space Studies (GISS)-E2 model comparing traditional highly parameterized volcanic implementation (specified Aerosol Optical Depth, Effective Radius) to deploying the full aerosol microphysics module MATRIX and directly emitting SO2 allowing us the prognosically determine the chemistry and climate impact. We show a reasonable match in aerosol optical depth, effective radius, and forcing between the full aerosol implementation and reconstructions/observations of the Mt. Pinatubo 1991 eruption, with a few areas as targets for future improvement. This allows us to investigate not only the climate impact of the injection of volcanic aerosols, but also influences on regional water vapor, O3, and OH distributions. With the skill of the MATRIX volcano implementation established, we explore (1) how the height of the injection column of SO2 influence atmospheric chemistry and climate response, (2) how the initial condition of the atmosphere influences the climate and chemistry impact of the eruption with a particular focus on how ENSO and QBO and (3) how the coupled chemistry could mitigate the climate signal for much larger eruptions (i.e., the 1258 eruption, reconstructed to be ~10x Pinatubo). During each sensitivity experiment we assess the impact on profiles of water vapor, O3, and OH, and assess how the eruption impacts the budget of each.

  15. Impact of improvements in volcanic implementation on atmospheric chemistry and climate in the GISS-E2 Model

    NASA Astrophysics Data System (ADS)

    LeGrande, A. N.; Tsigaridis, K.

    2014-12-01

    The representation of volcanic eruptions in climate models introduces some of the largest errors when evaluating historical simulations, partly due to the crude model parameterizations. We will show preliminary results from the Goddard Institute for Space Studies (GISS)-E2 model comparing traditional highly parameterized volcanic implementation (specified Aerosol Optical Depth, Effective Radius) to deploying the full aerosol modules (MATRIX) and directly emitting SO2 allowing us the prognosically determine the climate and chemistry impact. We show a reasonable match in aerosol optical depth, effective radius, and forcing between the full aerosol implementation and reconstructions/observations of the Mt. Pinatubo 1991 eruption, with a few areas as targets for future improvement. This allows us to investigate not only the climate impact of the injection of volcanic aerosols, but also influences on regional water vapor, O3, and OH distributions. With the skill of the MATRIX volcano implementation established, we explore (1) how the height of the injection column of SO2 influence atmospheric chemistry and climate response, (2) how the initial condition of the atmosphere influences the climate and chemistry impact of the eruption with a particular focus on how ENSO and QBO and (3) how the coupled chemistry could mitigate the climate signal for much larger eruptions (i.e., the 1258 eruption, reconstructed to be ~10x Pinatubo). During each sensitivity experiment we assess the impact on profiles of water vapor, O3, and OH, and assess how the eruption impacts the budget of each.

  16. Carbon Dioxide (CO2) Retrievals from Atmospheric Chemistry Experiment (ACE) Solar Occultation Measurements

    NASA Technical Reports Server (NTRS)

    Rinsland, Curtis P.; Chiou, Linda; Boone, Chris; Bernath, Peter

    2010-01-01

    The Atmospheric Chemistry Experiment ACE satellite (SCISAT-1) was launched into an inclined orbit on 12 August 2003 and is now recording high signal-to-noise 0.02 per centimeter resolution solar absorption spectra covering 750-4400 per centimeter (2.3-13 micrometers). A procedure has been developed for retrieving average dry air CO2 mole fractions (X(sub CO2)) in the altitude range 7-10 kilometers from the SCISAT-1 spectra. Using the N2 continuum absorption in a window region near 2500 per centimeter, altitude shifts are applied to the tangent heights retrieved in version 2.2 SCISAT-1 processing, while cloudy or aerosol-impacted measurements are eliminated. Monthly-mean XCO2 covering 60 S to 60 N latitude for February 2004 to March 2008 has been analyzed with consistent trends inferred in both hemispheres. The ACE XCO2 time series have been compared with previously-reported surface network measurements, predictions based on upper tropospheric aircraft measurements, and space-based measurements. The retrieved X(sub CO2) from the ACE-FTS spectra are higher on average by a factor of 1.07 plus or minus 0.025 in the northern hemisphere and by a factor of 1.09 plus or minus 0.019 on average in the southern hemisphere compared to surface station measurements covering the same time span. The ACE derived trend is approximately 0.2% per year higher than measured at surface stations during the same observation period.

  17. Afterglow chemistry of atmospheric-pressure helium-oxygen plasmas with humid air impurity

    NASA Astrophysics Data System (ADS)

    Murakami, Tomoyuki; Niemi, Kari; Gans, Timo; O'Connell, Deborah; Graham, William G.

    2014-04-01

    The formation of reactive species in the afterglow of a radio-frequency-driven atmospheric-pressure plasma in a fixed helium-oxygen feed gas mixture (He+0.5%O2) with humid air impurity (a few hundred ppm) is investigated by means of an extensive global plasma chemical kinetics model. As an original objective, we explore the effects of humid air impurity on the biologically relevant reactive species in an oxygen-dependent system. After a few milliseconds in the afterglow environment, the densities of atomic oxygen (O) decreases from 1015 to 1013 cm-3 and singlet delta molecular oxygen (O2(1D)) of the order of 1015 cm-3 decreases by a factor of two, while the ozone (O3) density increases from 1014 to 1015 cm-3. Electrons and oxygen ionic species, initially of the order of 1011 cm-3, recombine much faster on the time scale of some microseconds. The formation of atomic hydrogen (H), hydroxyl radical (OH), hydroperoxyl (HO2), hydrogen peroxide (H2O2), nitric oxide (NO) and nitric acid (HNO3) resulting from the humid air impurity as well as the influence on the afterglow chemistry is clarified with particular emphasis on the formation of dominant reactive oxygen species (ROS). The model suggests that the reactive species predominantly formed in the afterglow are major ROS O2(1D) and O3 (of the order of 1015 cm-3) and rather minor hydrogen- and nitrogen-based reactive species OH, H2O2, HNO3 and NO2/NO3, of which densities are comparable to the O-atom density (of the order of 1013 cm-3). Furthermore, the model quantitatively reproduces the experimental results of independent O and O3 density measurements.

  18. Response of an aerosol mass spectrometer to organonitrates and organosulfates and implications for atmospheric chemistry.

    PubMed

    Farmer, D K; Matsunaga, A; Docherty, K S; Surratt, J D; Seinfeld, J H; Ziemann, P J; Jimenez, J L

    2010-04-13

    Organonitrates (ON) are important products of gas-phase oxidation of volatile organic compounds in the troposphere; some models predict, and laboratory studies show, the formation of large, multifunctional ON with vapor pressures low enough to partition to the particle phase. Organosulfates (OS) have also been recently detected in secondary organic aerosol. Despite their potential importance, ON and OS remain a nearly unexplored aspect of atmospheric chemistry because few studies have quantified particulate ON or OS in ambient air. We report the response of a high-resolution time-of-flight aerosol mass spectrometer (AMS) to aerosol ON and OS standards and mixtures. We quantify the potentially substantial underestimation of organic aerosol O/C, commonly used as a metric for aging, and N/C. Most of the ON-nitrogen appears as NO(x)+ ions in the AMS, which are typically dominated by inorganic nitrate. Minor organonitrogen ions are observed although their identity and intensity vary between standards. We evaluate the potential for using NO(x)+ fragment ratios, organonitrogen ions, HNO(3)+ ions, the ammonium balance of the nominally inorganic ions, and comparison to ion-chromatography instruments to constrain the concentrations of ON for ambient datasets, and apply these techniques to a field study in Riverside, CA. OS manifests as separate organic and sulfate components in the AMS with minimal organosulfur fragments and little difference in fragmentation from inorganic sulfate. The low thermal stability of ON and OS likely causes similar detection difficulties for other aerosol mass spectrometers using vaporization and/or ionization techniques with similar or larger energy, which has likely led to an underappreciation of these species. PMID:20194777

  19. Research in Physical Chemistry and Chemical Education: Part A--Water Mediated Chemistry of Oxidized Atmospheric Compounds Part B--The Development of Surveying Tools to Determine How Effective Laboratory Experiments Contribute to Student Conceptual Understanding

    ERIC Educational Resources Information Center

    Maron, Marta Katarzyna

    2011-01-01

    This dissertation is a combination of two research areas, experimental physical chemistry, Chapters I to V, and chemical education, Chapters VI to VII. Chapters I to V describe research on the water-mediated chemistry of oxidized atmospheric molecules and the impact that water has on the spectra of these environmental systems. The role of water…

  20. Using "Household Chemistry Projects" To Develop Research Skills and To Teach Scientific Writing

    NASA Astrophysics Data System (ADS)

    Schmidt, Michael H.

    1997-04-01

    Students in a junior-level Chemistry library resources and scientific writing course were assigned semester-long "Household Chemistry Projects." Students were asked to independently develop written proposals for research they could do at their homes using ordinary household supplies. Upon approval of their proposals, students performed the research and wrote up in their results in standard journal format. The final drafts were subjected to peer review, and published in a class journal. Through feedback and rewriting, students not only improved their scientific writing skills, but also learned about designing, conducting, and criticizing research.

  1. A theoretical framework for volcanic degassing chemistry in a comparative planetology perspective and implications for planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Gaillard, Fabrice; Scaillet, Bruno

    2014-10-01

    Magmatic degassing is ubiquitous and enduring, yet its impact on both planetary surficial chemistry and how it may have varied among planetary systems remains imprecise. A large number of factors are likely to be involved in the control of magmatic gas compositions, leading roles being given to the redox state and volatile abundances in planetary interiors, and the fate of the latter during mantle melting. We however show that the pressure at which degassing occurs, that is the atmospheric pressure in most sensible cases, has a prime influence on the composition of subaerial volcanic gases on planets: high surface pressure produces N2- and CO2-rich and dry volcanic gases, while low pressure promotes sulfur-rich gases. In-between, atmospheric pressures close to 1 bar trigger volcanic gases dominated by H2O. This simple pattern broadly mirrors the atmospheres of Venus-Earth-Mars-Io planetary suite and constitutes benchmarks for the prediction and interpretation of atmospheric features of extra-solar planets. Volatile abundances within the planetary body interiors also matter but they play a secondary role. Furthermore, our analysis shows that any difference in redox conditions prevailing during partial melting tends to disappear with the degassing process itself, converging toward a unique - planetary oxygen fugacity - at the venting pressure. A feedback relationship between volcanic gas compositions and atmospheric pressure implies a runaway drying during atmospheric growth; that is volcanic gases must become CO2 richer as the atmospheric mass increases. This may explain some features of the Venusian atmosphere. On Earth, impact ejection of the atmosphere and CO2-sink mechanisms, such as carbonate precipitation and plate tectonics, must have decreased atmospheric pressure allowing the reestablishment of water-rich volcanic gases.

  2. Satellite Observations of Blowing Snow in and Around Antarctica: Implications for Ice Sheet Mass Balance and Atmospheric Chemistry

    NASA Astrophysics Data System (ADS)

    Palm, S. P.; Yang, Y.; Marshak, A.

    2014-12-01

    Blowing snow in the polar regions is known to be important for a variety of reasons including ice sheet mass balance, atmospheric water vapor transport, interpretation of paleoclimate records and atmospheric chemistry. Over Antarctica, persistent katabatic winds produce extreme blowing snow events often covering 100,000 square kilometers or more and reaching heights of 300-400 meters. New techniques of blowing snow detection using active and passive satellite data are providing a new understanding of the frequency, magnitude and spatial coverage of blowing snow over and around the Antarctic continent. Current research is utilizing these methods to obtain a nearly 10 year climatology of blowing snow events over Antarctica and estimate the amount of mass being blown off the continent and sublimated into the atmosphere on an annual basis. In addition, recent research indicates that blowing snow over sea ice may be important in the process of transporting seal salt aerosol into the atmosphere where it is implicated in the production of bromine compounds that strongly influence many aspects of tropospheric chemistry.

  3. Atmospheric chemistry of some concepts for engineered intervention into large-scale pollution problems

    SciTech Connect

    Elliott, S.; Prueitt, M.

    1994-12-31

    As the era of global change approaches, serious debate has begun on the merits of regional and global-scale atmospheric engineering enterprises to repair pollution damage. Post hoc mitigation schemes often prove to be inordinately expensive, and are sometimes dangerous. Here, chemical ramifications are discussed for three engineering concepts the authors are involved in assessing. Two of their projects regard global ozone depletion. It has been proposed that additions of small quantities of the light alkanes to the ozone hole could suppress massive springtime losses over Antarctica by scavenging chlorine atoms. A newly discovered heterogeneous reaction, however, implies that hydrogen atoms released during organic oxidation will activate the scavenged chlorine and more. Alkane injections could thus deepen the hole instead of plugging it. Ground based infrared laser multiple-photon dissociation has been suggested as a means for removing chlorofluorocarbons from the atmosphere before they can reach the ozone layer and cause depletions. The process would release chlorine atoms into the tropospheric system, and might lead to localized ozone production and smog-like plumes downwind of the laser assemblages. The third engineering proposal the authors are evaluating focuses on urban pollution. Reverse convection towers can generate electricity by channeling the cooling from evaporation of water droplets into controlled downdrafts. It has been noted that if the towers were constructed in cities, the falling drops within them would sweep out visibility-degrading particles. However, alterations in NO{sub x} could increase the intensity of midday ozone episodes. Their overall experience indicates that the direction and magnitude of potential chemical side effects of post hoc environmental engineering will be difficult to predict. 99 refs.

  4. The impact of temperature dependent CO2 cross section measurements: A role for heterogeneous chemistry in the atmosphere of Mars?

    NASA Technical Reports Server (NTRS)

    Anbar, A. D.; Allen, M.; Nair, H.; Leu, M-T.; Yung, Y. L.

    1992-01-01

    Carbon dioxide comprises over 95 percent of the Mars atmosphere, despite continuous photolysis of CO2 by solar ultraviolet (UV) radiation. Since the direct recombination of CO and O is spinforbidden, the chemical stability of CO2 in the Martian atmosphere is thought to be the result of a HO(x)-catalyzed recombination scheme. Thus the rate of CO oxidation is sensitive to the abundance and altitude distribution of OH, H, and HO2. Most Martian atmospheric models assume that HO(x) abundances are governed purely by gas phase chemistry. However, it is well established that reactive HO(x) radical are adsorbed by a wide variety of surfaces. The authors have combined laboratory studies of H, OH, and HO2 adsorption on inorganic surfaces, observational data of aerosol distributions, and an updated photochemical model to demonstrate that adsorption on either dust or ice aerosols is capable of reducing HO(x) abundances significantly, thereby retarding the rate of CO oxidation.

  5. Enhancing undergraduate students' chemistry understanding through project-based learning in an IT environment

    NASA Astrophysics Data System (ADS)

    Barak, Miri; Dori, Yehudit Judy

    2005-01-01

    Project-based learning (PBL), which is increasingly supported by information technologies (IT), contributes to fostering student-directed scientific inquiry of problems in a real-world setting. This study investigated the integration of PBL in an IT environment into three undergraduate chemistry courses, each including both experimental and control students. Students in the experimental group volunteered to carry out an individual IT-based project, whereas the control students solved only traditional problems. The project included constructing computerized molecular models, seeking information on scientific phenomena, and inquiring about chemistry theories. The effect of the PBL was examined both quantitatively and qualitatively. The quantitative analysis was based on a pretest, a posttest, and a final examination, which served for comparing the learning gains of the two research groups. For the qualitative analysis, we looked into the experimental students' performance, as reflected by the projects they had submitted. In addition, think alou interviews and observations helped us gain insight into the students' conceptual understanding of molecular structures. Students who participated in the IT-enhanced PBL performed significantly better than their control classmates not only on their posttest but also on their course final examination. Analyzing the qualitative findings, we concluded that the construction of computerized models and Web-based inquiry activities helped promote students' ability of mentally traversing the four levels of chemistry understanding: symbolic, macroscopic, microscopic, and process. More generally, our results indicated that incorporating IT-rich PBL into freshmen courses can enhance students' understanding of chemical concepts, theories, and molecular structures.

  6. The Impacts of Marine Organic Emissions on Atmospheric Chemistry and Climate (Invited)

    NASA Astrophysics Data System (ADS)

    Meskhidze, N.; Gantt, B.

    2013-12-01

    Using laboratory studies and global/regional climate model results, this talk will contribute to two main research questions: 1) what can be learned about the carbon emission inducing stress factors for marine algae, and 2) what is a potential impact of marine biogenic volatile organic compound (VOC) emissions on global atmospheric chemistry and climate. Marine photosynthetic organisms emit VOCs which can form secondary organic aerosols (SOA). Currently large uncertainty exists in the magnitude of the marine biogenic sources, their spatiotemporal distribution, controlling factors, and contributions to natural background of organic aerosols. Here laboratory results for the production of isoprene and four monoterpene (α-pinene, β-pinene, camphene and d-limonene) compounds as a function of variable light and temperature regimes for 6 different phytoplankton species will be discussed. The experiment was designed to simulate the regions where phytoplankton is subjected to changeable light/temperature conditions. The samples were grown and maintained at a climate controlled room. VOCs accumulated in the water and headspace above the water were measured by passing the sample through a gas chromatography/mass system equipped with a sample pre-concentrator allowing detection of low ppt levels of hydrocarbons. The VOC production rates were distinctly different for light/temperature stressed (the first 12 hour cycle at light/temperature levels higher than what the cultures were acclimated to in a climate controlled room) and photo/temperature-acclimated (the second 12 hour light/temperature cycle) states. In general, all phytoplankton species showed a rapid increase in isoprene and monoterpene production at higher light levels (between 150 to 420 μE m-2 s-1) until a constant production rate was reached. Isoprene and α-pinene, production rates also increased with temperature until a certain level, after which the rates declined as temperature increased further. Two

  7. Atmospheric Chemistry in Giant Planets, Brown Dwarfs, and Low-Mass Dwarf Stars. II. Sulfur and Phosphorus

    NASA Astrophysics Data System (ADS)

    Visscher, Channon; Lodders, Katharina; Fegley, Bruce, Jr.

    2006-09-01

    Thermochemical equilibrium and kinetic calculations are used to model sulfur and phosphorus chemistry in giant planets, brown dwarfs, and extrasolar giant planets (EGPs). The chemical behavior of individual S- and P-bearing gases and condensates is determined as a function of pressure, temperature, and metallicity. The results are independent of particular model atmospheres, and in principle, the equilibrium composition along the pressure-temperature profile of any object can be determined. Hydrogen sulfide (H2S) is the dominant S-bearing gas throughout substellar atmospheres and approximately represents the atmospheric sulfur inventory. Silicon sulfide (SiS) is a potential tracer of weather in substellar atmospheres. Disequilibrium abundances of phosphine (PH3) approximately representative of the total atmospheric phosphorus inventory are expected to be mixed upward into the observable atmospheres of giant planets and T dwarfs. In hotter objects, several P-bearing gases (e.g., P2, PH3, PH 2, PH, and HCP) become increasingly important at high temperatures.

  8. Chemistry Outreach Project to High Schools Using a Mobile Chemistry Laboratory, ChemKits, and Teacher Workshops

    ERIC Educational Resources Information Center

    Long, Gary L.; Bailey, Carol A.; Bunn, Barbara B.; Slebodnick, Carla; Johnson, Michael R.; Derozier, Shad

    2012-01-01

    The Chemistry Outreach Program (ChOP) of Virginia Tech was a university-based outreach program that addressed the needs of high school chemistry classes in underfunded rural and inner-city school districts. The primary features of ChOP were a mobile chemistry laboratory (MCL), a shipping-based outreach program (ChemKits), and teacher workshops.…

  9. On the plasma chemistry of a cold atmospheric argon plasma jet with shielding gas device

    NASA Astrophysics Data System (ADS)

    Schmidt-Bleker, Ansgar; Winter, Jörn; Bösel, André; Reuter, Stephan; Weltmann, Klaus-Dieter

    2016-02-01

    A novel approach combining experimental and numerical methods for the study of reaction mechanisms in a cold atmospheric \\text{Ar} plasma jet is introduced. The jet is operated with a shielding gas device that produces a gas curtain of defined composition around the plasma plume. The shielding gas composition is varied from pure {{\\text{N}}2} to pure {{\\text{O}}2} . The density of metastable argon \\text{Ar}≤ft(4\\text{s}{{,}3}{{\\text{P}}2}\\right) in the plasma plume was quantified using laser atom absorption spectroscopy. The density of long-living reactive oxygen and nitrogen species (RONS), namely {{\\text{O}}3} , \\text{N}{{\\text{O}}2} , \\text{NO} , {{\\text{N}}2}\\text{O} , {{\\text{N}}2}{{\\text{O}}5} and {{\\text{H}}2}{{\\text{O}}2} , was quantified in the downstream region of the jet in a multipass cell using Fourier-transform infrared spectroscopy (FTIR). The jet produces a turbulent flow field and features guided streamers propagating at several \\text{km}~{{\\text{s}}-1} that follow the chaotic argon flow pattern, yielding a plasma plume with steep spatial gradients and a time dependence on the \\text{ns} scale while the downstream chemistry unfolds within several seconds. The fast and highly localized electron impact reactions in the guided streamer head and the slower gas phase reactions of neutrals occurring in the plasma plume and experimental apparatus are therefore represented in two separate kinetic models. The first electron impact reaction kinetics model is correlated to the LAAS measurements and shows that in the guided streamer head primary reactive oxygen and nitrogen species are dominantly generated from \\text{Ar}≤ft(4\\text{s}{{,}3}{{\\text{P}}2}\\right) . The second neutral species plug-flow model hence uses an \\text{Ar}≤ft(4\\text{s}{{,}3}{{\\text{P}}2}\\right) source term as sole energy input and yields good agreement with the RONS measured by FTIR spectroscopy.

  10. Exploring Atmospheric Aqueous Chemistry (and Secondary Organic Aerosol Formation) through OH Radical Oxidation Experiments, Droplet Evaporation and Chemical Modeling

    NASA Astrophysics Data System (ADS)

    Turpin, B. J.; Kirkland, J. R.; Lim, Y. B.; Ortiz-Montalvo, D. L.; Sullivan, A.; Häkkinen, S.; Schwier, A. N.; Tan, Y.; McNeill, V. F.; Collett, J. L.; Skog, K.; Keutsch, F. N.; Sareen, N.; Carlton, A. G.; Decesari, S.; Facchini, C.

    2013-12-01

    Gas phase photochemistry fragments and oxidizes organic emissions, making water-soluble organics ubiquitous in the atmosphere. My group and others have found that several water-soluble compounds react further in the aqueous phase forming low volatility products under atmospherically-relevant conditions (i.e., in clouds, fogs and wet aerosols). Thus, secondary organic aerosol can form as a result of gas followed by aqueous chemistry (aqSOA). We have used aqueous OH radical oxidation experiments coupled with product analysis and chemical modeling to validate and refine the aqueous chemistry of glyoxal, methylglyoxal, glycolaldehyde, and acetic acid. The resulting chemical model has provided insights into the differences between oxidation chemistry in clouds and in wet aerosols. Further, we conducted droplet evaporation experiments to characterize the volatility of the products. Most recently, we have conducted aqueous OH radical oxidation experiments with ambient mixtures of water-soluble gases to identify additional atmospherically-important precursors and products. Specifically, we scrubbed water-soluble gases from the ambient air in the Po Valley, Italy using four mist chambers in parallel, operating at 25-30 L min-1. Aqueous OH radical oxidation experiments and control experiments were conducted with these mixtures (total organic carbon ≈ 100 μM-C). OH radicals (3.5E-2 μM [OH] s-1) were generated by photolyzing H2O2. Precursors and products were characterized using electrospray ionization mass spectrometry (ESI-MS), ion chromatography (IC), IC-ESI-MS, and ultra high resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Chemical modeling suggests that organic acids (e.g., oxalate, pyruvate, glycolate) are major products of OH radical oxidation at cloud-relevant concentrations, whereas organic radical - radical reactions result in the formation of oligomers in wet aerosols. Products of cloud chemistry and droplet evaporation have

  11. Photochemistry of Saturn's Atmosphere. 1; Hydrocarbon Chemistry and Comparisons with ISO Observations

    NASA Technical Reports Server (NTRS)

    Moses, Julianne I.; Bezard, Bruno; Lellouch, Emmanuel; Gladstone, G. Randall; Feuchtgruber, Helmut; Allen, Mark

    2000-01-01

    To investigate the details of hydrocarbon photochemistry on Saturn, we have developed a one-dimensional diurnally averaged model that couples hydrocarbon and oxygen photochemistry, molecular and eddy diffusion, radiative transfer, and condensation. The model results are compared with observations from the Infrared Space Observatory (ISO) to place tighter constraints on molecular abundances, to better define Saturn's eddy diffusion coefficient profile, and to identify important chemical schemes that control the abundances of the observable hydrocarbons in Saturn's upper atmosphere. From the ISO observations, we determine that the column 12 densities of CH3, CH3C2H, and C4H2 above 10 mbar are 4 (sup +2) (sub -1.5) x 10 (exp 13) cm (sup -2), (1.1 plus or minus 0.3) x 10 (exp 15) cm (exp -2), and (1.2 plus or minus 0.3) x 10 (exp 14) cm (sup -2), respectively. The observed ISO emission features also indicate C2H2 mixing ratios of 1.2 (sup +0.9) (sub -0.6) x 10 (exp -6) at 0.3 mbar and (2.7 plus or minus 0.8) x 10 (exp -7) at 1.4 mbar, and a C2H6 mixing ratio of (9 plus or minus 2.5) x 10 (exp -6) at 0.5 mbar. Upper limits are provided for C2H4, CH2CCH2, C3H8, and C6H2 sensitivity of the model results to variations in the eddy diffusion coefficient profile, the solar flux, the CH4 photolysis branching ratios, the atomic hydrogen influx, and key reaction rates are discussed in detail. We find that C4H2 and CH3C2H are particularly good tracers of important chemical processes and physical conditions in Saturn's upper atmosphere, and C2H6 is a good tracer of the eddy diffusion coefficient in Saturn's lower stratosphere. The eddy diffusion coefficient must be smaller than approximately 3 x 10 (exp 4) sq cm s (sup -1) at pressures greater than 1 mbar in order to reproduce the C2H6 abundance inferred from ISO observations. The eddy diffusion coefficients in the upper stratosphere could be constrained by observations of CH3 radicals if the low-temperature chemistry of CH3 were

  12. Project Longhorn: A Pilot Project in the Use of Batch Computing in High School Chemistry Teaching.

    ERIC Educational Resources Information Center

    Busboom, Sally Young

    1997-01-01

    Describes the use of batch-oriented computing as the basis for reintroducing homework problems as a teaching tool in beginning chemistry instruction. Stems from and expands upon a system used in a university setting that produces, delivers, grades, and keeps records for homework problems. (DDR)

  13. Downward transport of ozone rich air and implications for atmospheric chemistry in the Amazon rainforest

    NASA Astrophysics Data System (ADS)

    Gerken, Tobias; Wei, Dandan; Chase, Randy J.; Fuentes, Jose D.; Schumacher, Courtney; Machado, Luiz A. T.; Andreoli, Rita V.; Chamecki, Marcelo; Ferreira de Souza, Rodrigo A.; Freire, Livia S.; Jardine, Angela B.; Manzi, Antonio O.; Nascimento dos Santos, Rosa M.; von Randow, Celso; dos Santos Costa, Patrícia; Stoy, Paul C.; Tóta, Julio; Trowbridge, Amy M.

    2016-01-01

    From April 2014 to January 2015, ozone (O3) dynamics were investigated as part of GoAmazon 2014/5 project in the central Amazon rainforest of Brazil. Just above the forest canopy, maximum hourly O3 mixing ratios averaged 20 ppbv (parts per billion on a volume basis) during the June-September dry months and 15 ppbv during the wet months. Ozone levels occasionally exceeded 75 ppbv in response to influences from biomass burning and regional air pollution. Individual convective storms transported O3-rich air parcels from the mid-troposphere to the surface and abruptly enhanced the regional atmospheric boundary layer by as much as 25 ppbv. In contrast to the individual storms, days with multiple convective systems produced successive, cumulative ground-level O3 increases. The magnitude of O3 enhancements depended on the vertical distribution of O3 within storm downdrafts and origin of downdrafts in the troposphere. Ozone mixing ratios remained enhanced for > 2 h following the passage of storms, which enhanced chemical processing of rainforest-emitted isoprene and monoterpenes. Reactions of isoprene and monoterpenes with O3 are modeled to generate maximum hydroxyl radical formation rates of 6 × 106 radicals cm-3s-1. Therefore, one key conclusion of the present study is that downdrafts of convective storms are estimated to transport enough O3 to the surface to initiate a series of reactions that reduce the lifetimes of rainforest-emitted hydrocarbons.

  14. PREP-CHEM-SRC - 1.0: a preprocessor of trace gas and aerosol emission fields for regional and global atmospheric chemistry models

    NASA Astrophysics Data System (ADS)

    Freitas, S. R.; Longo, K. M.; Alonso, M. F.; Pirre, M.; Marecal, V.; Grell, G.; Stockler, R.; Mello, R. F.; Sánchez Gácita, M.

    2011-05-01

    The preprocessor PREP-CHEM-SRC presented in the paper is a comprehensive tool aiming at preparing emission fields of trace gases and aerosols for use in atmospheric-chemistry transport models. The considered emissions are from the most recent databases of urban/industrial, biogenic, biomass burning, volcanic, biofuel use and burning from agricultural waste sources. For biomass burning, emissions can be also estimated directly from satellite fire detections using a fire emission model included in the tool. The preprocessor provides emission fields interpolated onto the transport model grid. Several map projections can be chosen. The inclusion of these emissions in transport models is also presented. The preprocessor is coded using Fortran90 and C and is driven by a namelist allowing the user to choose the type of emissions and the databases.

  15. LABORATORY AND COMPUTATIONAL INVESTIGATIONS OF THE ATMOSPHERIC CHEMISTRY OF KEY OXIDATION PRODUCTS CONTROLLING TROPOSPHERIC OZONE FORMATION

    EPA Science Inventory

    Major uncertainties remain in our ability to identify the key reactions and primary oxidation products of volatile hydrocarbons that contribute to ozone formation in the troposphere. To reduce these uncertainties, computational chemistry, mechanistic and process analysis techniqu...

  16. Finite-rate chemistry effects upon convective and radiative heating of an atmospheric entry vehicle. [reentry aerothermochemistry

    NASA Technical Reports Server (NTRS)

    Guillermo, P.

    1975-01-01

    A mathematical model of the aerothermochemical environment along the stagnation line of a planetary return spacecraft using an ablative thermal protection system was developed and solved for conditions typical of atmospheric entry from planetary missions. The model, implemented as a FORTRAN 4 computer program, was designed to predict viscous, reactive and radiative coupled shock layer structure and the resulting body heating rates. The analysis includes flow field coupling with the ablator surface, binary diffusion, coupled line and continuum radiative and equilibrium or finite rate chemistry effects. The gas model used includes thermodynamic, transport, kinetic and radiative properties of air and ablation product species, including 19 chemical species and 16 chemical reactions. Specifically, the impact of nonequilibrium chemistry effects upon stagnation line shock layer structure and body heating rates was investigated.

  17. A two-dimensional atmospheric chemistry modeling investigation of Earth's Phanerozoic O3 and near-surface ultraviolet radiation history

    NASA Astrophysics Data System (ADS)

    Harfoot, Michael B. J.; Beerling, David J.; Lomax, Barry H.; Pyle, John A.

    2007-04-01

    We use the Cambridge two-dimensional (2-D) chemistry-radiation transport model to investigate the implications for column O3 and near-surface ultraviolet radiation (UV), of variations in atmospheric O2 content over the Phanerozoic (last 540 Myr). Model results confirm some earlier 1-D model investigations showing that global annual mean O3 column increases monotonically with atmospheric O2. Sensitivity studies indicate that changes in temperature and N2O exert a minor influence on O3 relative to O2. We reconstructed Earth's O3 history by interpolating the modeled relationship between O3 and O2 onto two Phanerozoic O2 histories. Our results indicate that the largest variation in Phanerozoic column O3 occurred between 400 and 200 Myr ago, corresponding to a rise in atmospheric O2 to ˜1.5 times the present atmospheric level (PAL) and subsequent fall to ˜0.5 PAL. The O3 response to this O2 decline shows latitudinal differences, thinning most at high latitudes (30-40 Dobson units (1 DU = 0.001 atm cm) at 66°N) and least at low latitudes (5-10 DU at 9°N) where a "self-healing" effect is evident. This O3 depletion coincides with significant increases in the near-surface biologically active UV radiation at high latitudes, +28% as weighted by the Thimijan spectral weighting function. O3 and UV changes were exacerbated when we incorporated a direct feedback of the terrestrial biosphere on atmospheric chemistry, through enhanced N2O production as the climate switched from an icehouse to a greenhouse mode. On the basis of a summary of field and laboratory experimental evidence, we suggest that these UV radiation increases may have exerted subtle rather than catastrophic effects on ecosystem processes.

  18. Interfacial Atmospheric Chemistry: Quantum Chemical Calculations on the Mechanism of Protonation and Oligomerization of Isoprene on Aqueous Surfaces

    NASA Astrophysics Data System (ADS)

    Mishra, H.; Colussi, A. J.; Enami, S.; Nielsen, R. J.; Hoffmann, M. R.; Goddard, W. A.

    2012-12-01

    It has become increasingly apparent that atmospheric chemistry involves more than gas-phase reactions. Key processes, such as the decay of NO2 in urban plumes and the associated daytime formation of HONO, and the rapid chemistries observed in and over forest canopies at nighttime defy explanation by conventional atmospheric chemistry mechanisms. We have recently reported experimental results on several gas-liquid reactions of atmospheric interest, such as the facile protonation of gaseous isoprene on mildly acidic (pH < 4) water. Although interfacial proton transfers, such as the one involved in the protonation of gaseous isoprene, also participate in cloud and ocean acidification, bioenergetics coupling, 'on-water' catalysis, self-assembly and molecular recognition, little is known about the molecular mechanisms of such reactions. Herein we apply quantum mechanics to investigate how biogenic or anthropogenic olefins may get protonated and undergo oligomerization at the air-water interface by performing model calculations on small water clusters carrying an excess proton as surrogates for the surface of mildly acidic water as sensed by gaseous isoprene (ISO). We find that ISO binds weakly to the surface of water and accepts a proton from H+(H2O)3, leading to ISOH+ via a proton transfer hindered by a ΔG1‡ = 5.6 kcal mol-1 kinetic barrier. Subsequently, another ISO attaches loosely to this ensemble, before being attacked by the ISOH+. This process, which represents the first step of the cationic polymerization of ISO, is hindered by a similar ΔG2‡ = 5.7 kcal mol-1 barrier. Our theoretical results are consistent with experimental (~ 10-4) uptake coefficients for ISO measured on acidic water.

  19. Simulating atmospheric composition over a South-East Asian tropical rainforest: performance of a chemistry box model

    NASA Astrophysics Data System (ADS)

    Pugh, T. A. M.; MacKenzie, A. R.; Hewitt, C. N.; Langford, B.; Edwards, P. M.; Furneaux, K. L.; Heard, D. E.; Hopkins, J. R.; Jones, C. E.; Karunaharan, A.; Lee, J.; Mills, G.; Misztal, P.; Moller, S.; Monks, P. S.; Whalley, L. K.

    2010-01-01

    Atmospheric composition and chemistry above tropical rainforests is currently not well established, particularly for south-east Asia. In order to examine our understanding of chemical processes in this region, the performance of a box model of atmospheric boundary layer chemistry is tested against measurements made at the top of the rainforest canopy near Danum Valley, Malaysian Borneo. Multi-variate optimisation against ambient concentration measurements was used to estimate average canopy-scale emissions for isoprene, total monoterpenes and nitric oxide. The excellent agreement between estimated values and measured fluxes of isoprene and total monoterpenes provides confidence in the overall modelling strategy, and suggests that this method may be applied where measured fluxes are not available, assuming that the local chemistry and mixing are adequately understood. The largest contributors to the optimisation cost function at the point of best-fit are OH (29%), NO (22%) and total peroxy radicals (27%). Several factors affect the modelled VOC chemistry. In particular concentrations of methacrolein (MACR) and methyl-vinyl ketone (MVK) are substantially overestimated, and the hydroxyl radical (OH) concentration is substantially underestimated; as has been seen before in tropical rainforest studies. It is shown that inclusion of dry deposition of MACR and MVK and wet deposition of species with high Henry's Law values substantially improves the fit of these oxidised species, whilst also substantially decreasing the OH sink. Increasing OH production arbitrarily, through a simple OH recycling mechanism , adversely affects the model fit for volatile organic compounds (VOCs). Given the constraints on isoprene flux provided by measurements, a substantial decrease in the rate of reaction of VOCs with OH is the only remaining option to explain the measurement/model discrepancy for OH. A reduction in the isoprene+OH rate constant of 50%, in conjunction with increased

  20. Probing Heterogeneous Chemistry of Individual Atmospheric Particles Using Scanning Electron Microscopy and Energy-Dispersive X-ray Analysis

    SciTech Connect

    Krueger, Brenda J.; Grassian, Vicki H.; Iedema, Martin J.; Cowin, James P.; Laskin, Alexander

    2003-10-01

    In this paper, we demonstrate the utility of single-particle analysis to investigate the chemistry of isolated, individual particles of atmospheric relevance such as NaCl, sea salt, CaCO3, and SiO2. A variety of state-of-th-art scanning electron microscopy techniques, including environmental scanning electon microscopy and computer-controlled scanning electron microscopy/energy-dispersive X-ray analysis, were utilized for monitoring and quantifying phase transitions of individual particles, morphology, and compositional changes of individual particles as they react with nitric acid.

  1. Cooperative and Context-Based Learning on Eletrochemical Cells in Lower Secondary Chemistry: A Project of Participatory Action Research

    ERIC Educational Resources Information Center

    Markic, Silvija; Eilks, Ingo

    2006-01-01

    This paper discusses a project of Participatory Action Research (PAR) on lower secondary chemistry education. In this ongoing project, practicing teachers and university researchers in chemical education jointly carry out projects for developing and evaluating new lesson plans. The focus of the PAR group is to develop teaching/learning activities…

  2. Integrating Project-Based Service-Learning into an Advanced Environmental Chemistry Course

    NASA Astrophysics Data System (ADS)

    Draper, Alison J.

    2004-02-01

    In an advanced environmental chemistry course, the inclusion of semester-long scientific service projects successfully integrated the research process with course content. Each project involved a unique community-based environmental analysis in which students assessed an aspect of environmental health. The projects were due in small pieces at even intervals, and students worked independently or in pairs. Initially, students wrote a project proposal in which they chose and justified a project. Following a literature review of their topic, they drafted sampling and analysis plans using methods in the literature. Samples were collected and analyzed, and all students assembled scientific posters describing the results of their study. In the last week of the semester, the class traveled to a regional professional meeting to present the posters. In all, students found the experience valuable. They learned to be professional environmental chemists and learned the value of the discipline to community health. Students not only learned about their own project in depth, but they were inspired to learn textbook material, not for an exam, but because it helped them understand their own project. Finally, having a community to answer to at the end of the project motivated students to do careful work.

  3. Triple Isotopic Composition of Atmospheric Carbonates: A Novel Technique to Identify Heterogeneous Chemistry on Aerosol Surfaces in Polluted Environment

    NASA Astrophysics Data System (ADS)

    Shaheen, R.; Horn, J.; Dominguez, G.; Masterson, A.; Ivanov, A. V.; Thiemens, M. H.

    2009-12-01

    In the ambient atmosphere, the physical and chemical properties of aerosol vary greatly between location and time due to various heterogeneous and photochemical reactions in the atmosphere. In polluted urban environments, the aerosol and gaseous mixtures interact to produce new compounds and particulates; consequently humans are exposed to many as yet undetected species. Studies of actual chemically-active, airborne particulates can better address the interaction of complex particulate and gaseous pollutant mixtures, however, it is notoriously difficult to measure chemical transformations of aerosols. Here we describe a new technique that can be used to understand the chemical transformation occurring on the surface of aerosols and thus to quantify the interaction of gaseous species and aerosol in the atmosphere. Fine and coarse aerosol samples were collected on filter papers in La Jolla, CA, USA for one week. The aerosol samples were digested with phosphoric acid and CO2 released was purified chromatographically and analyzed for 13 C. To obtain independent measurements of oxygen isotopes, the CO2 was fluorinated and oxygen gas obtained was analyzed using Mat253 Isotope Ratio Mass Spectrometer. The data indicated an excess 17O (0.6 to 4‰) in atmospheric carbonates. The oxygen isotope anomaly in atmospheric carbonates has been observed for the first time and it showed a highly significant correlation (r2 = 0.90) with urban index; an indirect measure of ozone chemistry. The δ13C in atmospheric carbonates was found to vary from -18 to -40‰. Controlled laboratory experiments to understand the origin and variation in the C and O isotopic composition of atmospheric carbonates were conducted using various mineral surfaces. Isotopic measurements of in-situ formed carbonated on CaOH, CaO, MgO, SiO2,Cu, CuO, Ni and Fe2O3 due to chemisorbed CO2 in the presence of thin water films were performed and we found that the δ13C in these carbonates ranged from -12 to -24

  4. Simulating atmospheric composition over a South-East Asian tropical rainforest: Performance of a chemistry box model

    NASA Astrophysics Data System (ADS)

    Pugh, T. A. M.; MacKenzie, A. R.; Hewitt, C. N.; Langford, B.; Edwards, P. M.; Furneaux, K. L.; Heard, D. E.; Hopkins, J. R.; Jones, C. E.; Karunaharan, A.; Lee, J.; Mills, G.; Misztal, P.; Moller, S.; Monks, P. S.; Whalley, L. K.

    2009-09-01

    Atmospheric composition and chemistry above tropical rainforests is currently not well established, particularly for south-east Asia. In order to examine our understanding of chemical processes in this region, the performance of a box model of atmospheric boundary layer chemistry is tested against measurements made at the top of the rainforest canopy near Danum Valley, Malaysian Borneo. Multi-variate optimisation against ambient concentration measurements was used to estimate average canopy-scale emissions for isoprene, total monoterpenes and nitric oxide. The excellent agreement between estimated values and measured fluxes of isoprene and total monoterpenes provides confidence in the overall modelling strategy, and suggests that this method may be applied where measured fluxes are not available. The largest contributors to the optimisation cost function at the point of best-fit are OH (41%), NO (18%) and total monoterpenes (16%). Several factors affect the modelled VOC chemistry. In particular concentrations of methacrolein (MACR) and methyl-vinyl ketone (MVK) are substantially overestimated, and the hydroxyl radical [OH] concentration is substantially underestimated; as has been seen before in tropical rainforest studies. It is shown that inclusion of dry deposition of MACR and MVK and wet deposition of species with high Henry's Law values substantially improves the fit of these oxidised species, whilst also substantially decreasing the OH sink. Increasing [OH] production arbitrarily, through a simple OH recycling mechanism, adversely affects the model fit for volatile organic compounds (VOCs). Given the constraints on isoprene flux provided by measurements, a substantial decrease in the rate of reaction of VOCs with OH is the only remaining option to explain the measurement/model discrepancy for OH. A reduction in the isoprene + OH rate constant of 50-70% is able to produce both isoprene and OH concentrations within error of those measured. Whilst we cannot rule

  5. DISEQUILIBRIUM CARBON, OXYGEN, AND NITROGEN CHEMISTRY IN THE ATMOSPHERES OF HD 189733b AND HD 209458b

    SciTech Connect

    Moses, Julianne I.; Visscher, C.; Fortney, J. J.; Showman, A. P.; Lewis, N. K.; Griffith, C. A.; Klippenstein, S. J.; Shabram, M.; Friedson, A. J.; Marley, M. S.; Freedman, R. S.

    2011-08-10

    We have developed a one-dimensional photochemical and thermochemical kinetics and diffusion model to study the effects of disequilibrium chemistry on the atmospheric composition of 'hot-Jupiter' exoplanets. Here we investigate the coupled chemistry of neutral carbon, hydrogen, oxygen, and nitrogen species on HD 189733b and HD 209458b and we compare the model results with existing transit and eclipse observations. We find that the vertical profiles of molecular constituents are significantly affected by transport-induced quenching and photochemistry, particularly on the cooler HD 189733b; however, the warmer stratospheric temperatures on HD 209458b help maintain thermochemical equilibrium and reduce the effects of disequilibrium chemistry. For both planets, the methane and ammonia mole fractions are found to be enhanced over their equilibrium values at pressures of a few bar to less than an mbar due to transport-induced quenching, but CH{sub 4} and NH{sub 3} are photochemically removed at higher altitudes. Disequilibrium chemistry also enhances atomic species, unsaturated hydrocarbons (particularly C{sub 2}H{sub 2}), some nitriles (particularly HCN), and radicals like OH, CH{sub 3}, and NH{sub 2}. In contrast, CO, H{sub 2}O, N{sub 2}, and CO{sub 2} more closely follow their equilibrium profiles, except at pressures {approx}<1 {mu}bar, where CO, H{sub 2}O, and N{sub 2} are photochemically destroyed and CO{sub 2} is produced before its eventual high-altitude destruction. The enhanced abundances of CH{sub 4}, NH{sub 3}, and HCN are expected to affect the spectral signatures and thermal profiles of HD 189733b and other relatively cool, transiting exoplanets. We examine the sensitivity of our results to the assumed temperature structure and eddy diffusion coefficients and discuss further observational consequences of these models.

  6. Aviation Safety Program Atmospheric Environment Safety Technologies (AEST) Project

    NASA Technical Reports Server (NTRS)

    Colantonio, Ron

    2011-01-01

    Engine Icing: Characterization and Simulation Capability: Develop knowledge bases, analysis methods, and simulation tools needed to address the problem of engine icing; in particular, ice-crystal icing Airframe Icing Simulation and Engineering Tool Capability: Develop and demonstrate 3-D capability to simulate and model airframe ice accretion and related aerodynamic performance degradation for current and future aircraft configurations in an expanded icing environment that includes freezing drizzle/rain Atmospheric Hazard Sensing and Mitigation Technology Capability: Improve and expand remote sensing and mitigation of hazardous atmospheric environments and phenomena

  7. Long Term Monitoring Trends In The Southeastern U.S.: Changes In Atmospheric Chemistry?

    NASA Astrophysics Data System (ADS)

    Blanchard, C. L.; Hidy, G. M.

    2013-12-01

    The SOS/SEARCH network has measured air pollutant concentrations in the southeastern U.S. since 1992, providing context for the 2013 Southeastern Organic Aerosol Study (SOAS). Ambient concentrations and species ratios indicate evolution in atmospheric chemistry. Since 1999, ~50 percent decreases in anthropogenic SOx, NOx, CO, and VOC emissions reduced gas and fine particle concentrations at all SEARCH sites. Primary but not secondary pollutant concentration decreases were approximately proportional to emission declines. Mean annual ambient SO2 mixing ratios at rural SEARCH sites decreased in proportion to annual SO2 emissions, whereas mean annual PM2.5 sulfate (SO4) concentrations decreased until 2009 but then showed minimal change despite continuing SO2 emission reductions. This difference suggests a change in oxidant-SO2 relationships. Between 1999 and 2012, the mean ratios of SO2/SOx (SOx = SO2 + SO4, molar basis) decreased from 0.68 × 0.04 to 0.57 × 0.05 and from 0.73 × 0.05 to 0.59 × 0.05 at two rural sites, indicating changes in SO4 production. Mean annual mixing ratios of oxidized nitrogen species (NOy) at rural sites decreased from 5.8 × 1.9 ppbv in 1992 to 4.8 × 1.4 ppbv in 2002 and 2.4 × 0.5 ppbv in 2012, proportional to NOx emission changes. Mean annual afternoon (noon through 4 p.m.) ratios of NOz/NOy (NOz = NOy - NOx) at rural sites varied between 0.36 and 0.63 from 1997 to 2011, without showing trends. Mean afternoon O3/NOy ratios increased at both urban and non-urban sites, e.g., from 8.3 × 0.4 in 1992 to 11.5 × 0.5 in 1999 and 19.9 × 0.9 in 2011 in rural Alabama, and from 2.0 × 0.1 in 1999 to 4.9 × 0.3 in 2011 in Atlanta, suggesting increased oxidation rates. Regression of daily peak 8-hour O3 against afternoon NOz yielded slopes ranging from urban 4.02 × 0.15 to rural 11.32 × 0.42, reflecting higher O3 production efficiency (OPE) at rural compared to urban sites. The OPE exhibited year-to-year variability with increasing trends at

  8. The atmospheric chemistry general circulation model ECHAM5/MESSy1: consistent simulation of ozone from the surface to the mesosphere

    NASA Astrophysics Data System (ADS)

    Jöckel, P.; Tost, H.; Pozzer, A.; Brühl, C.; Buchholz, J.; Ganzeveld, L.; Hoor, P.; Kerkweg, A.; Lawrence, M. G.; Sander, R.; Steil, B.; Stiller, G.; Tanarhte, M.; Taraborrelli, D.; van Aardenne, J.; Lelieveld, J.

    2006-07-01

    The new Modular Earth Submodel System (MESSy) describes atmospheric chemistry and meteorological processes in a modular framework, following strict coding standards. It has been coupled to the ECHAM5 general circulation model, which has been slightly modified for this purpose. A 90-layer model version up to 0.01 hPa was used at T42 resolution (~2.8 latitude and longitude) to simulate the lower and middle atmosphere. The model meteorology has been tested to check the influence of the changes to ECHAM5 and the radiation interactions with the new representation of atmospheric composition. A Newtonian relaxation technique was applied in the tropospheric part of the domain to weakly nudge the model towards the analysed meteorology during the period 1998-2005. It is shown that the tropospheric wave forcing of the stratosphere in the model suffices to reproduce the Quasi-Biennial Oscillation and major stratospheric warming events leading e.g. to the vortex split over Antarctica in 2002. Characteristic features such as dehydration and denitrification caused by the sedimentation of polar stratospheric cloud particles and ozone depletion during winter and spring are simulated accurately, although ozone loss in the lower polar stratosphere is slightly underestimated. The model realistically simulates stratosphere-troposphere exchange processes as indicated by comparisons with satellite and in situ measurements. The evaluation of tropospheric chemistry presented here focuses on the distributions of ozone, hydroxyl radicals, carbon monoxide and reactive nitrogen compounds. In spite of minor shortcomings, mostly related to the relatively coarse T42 resolution and the neglect of interannual changes in biomass burning emissions, the main characteristics of the trace gas distributions are generally reproduced well. The MESSy submodels and the ECHAM5/MESSy1 model output are available through the internet on request.

  9. The atmospheric chemistry general circulation model ECHAM5/MESSy1: consistent simulation of ozone from the surface to the mesosphere

    NASA Astrophysics Data System (ADS)

    Jöckel, P.; Tost, H.; Pozzer, A.; Brühl, C.; Buchholz, J.; Ganzeveld, L.; Hoor, P.; Kerkweg, A.; Lawrence, M. G.; Sander, R.; Steil, B.; Stiller, G.; Tanarhte, M.; Taraborrelli, D.; van Aardenne, J.; Lelieveld, J.

    2006-11-01

    The new Modular Earth Submodel System (MESSy) describes atmospheric chemistry and meteorological processes in a modular framework, following strict coding standards. It has been coupled to the ECHAM5 general circulation model, which has been slightly modified for this purpose. A 90-layer model setup up to 0.01 hPa was used at spectral T42 resolution to simulate the lower and middle atmosphere. With the high vertical resolution the model simulates the Quasi-Biennial Oscillation. The model meteorology has been tested to check the influence of the changes to ECHAM5 and the radiation interactions with the new representation of atmospheric composition. In the simulations presented here a Newtonian relaxation technique was applied in the tropospheric part of the domain to weakly nudge the model towards the analysed meteorology during the period 1998-2005. This allows an efficient and direct evaluation with satellite and in-situ data. It is shown that the tropospheric wave forcing of the stratosphere in the model suffices to reproduce major stratospheric warming events leading e.g. to the vortex split over Antarctica in 2002. Characteristic features such as dehydration and denitrification caused by the sedimentation of polar stratospheric cloud particles and ozone depletion during winter and spring are simulated well, although ozone loss in the lower polar stratosphere is slightly underestimated. The model realistically simulates stratosphere-troposphere exchange processes as indicated by comparisons with satellite and in situ measurements. The evaluation of tropospheric chemistry presented here focuses on the distributions of ozone, hydroxyl radicals, carbon monoxide and reactive nitrogen compounds. In spite of minor shortcomings, mostly related to the relatively coarse T42 resolution and the neglect of inter-annual changes in biomass burning emissions, the main characteristics of the trace gas distributions are generally reproduced well. The MESSy submodels and the

  10. Role of Atmospheric Chemistry in the Climate Impacts of Stratospheric Volcanic Injections

    NASA Technical Reports Server (NTRS)

    Legrande, Allegra N.; Tsigaridis, Kostas; Bauer, Susanne E.

    2016-01-01

    The climate impact of a volcanic eruption is known to be dependent on the size, location and timing of the eruption. However, the chemistry and composition of the volcanic plume also control its impact on climate. It is not just sulfur dioxide gas, but also the coincident emissions of water, halogens and ash that influence the radiative and climate forcing of an eruption. Improvements in the capability of models to capture aerosol microphysics, and the inclusion of chemistry and aerosol microphysics modules in Earth system models, allow us to evaluate the interaction of composition and chemistry within volcanic plumes in a new way. These modeling efforts also illustrate the role of water vapor in controlling the chemical evolution, and hence climate impacts, of the plume. A growing realization of the importance of the chemical composition of volcanic plumes is leading to a more sophisticated and realistic representation of volcanic forcing in climate simulations, which in turn aids in reconciling simulations and proxy reconstructions of the climate impacts of past volcanic eruptions. More sophisticated simulations are expected to help, eventually, with predictions of the impact on the Earth system of any future large volcanic eruptions.

  11. A high-resolution Sulphur Isotope Record of Neoarchean Atmospheric Chemistry: Deciphering the Driver of Atmospheric Bi-stability in the Prelude to the GOE.

    NASA Astrophysics Data System (ADS)

    Izon, G. J.; Zerkle, A.; Newton, R.; Poulton, S.; Eigenbrode, J.; Farquhar, J.; Claire, M.

    2014-12-01

    Quantitative estimates of the composition of the Late Archean atmosphere are integral to deciphering the drivers of planetary oxygenation in the early Paleoproterozoic. However, the majority of geochemical proxies from marine sediments only inform on planetary redox via inference, making direct constraints on the ancient atmosphere difficult to place. Fortunately, the quadruple S-isotope (QSI) record (δ34S, Δ33S, and Δ36S) is implicitly tied to the composition of the ancient atmosphere. We have generated coupled QSI and δ13COrg records from two cores through the Transvaal basin in South Africa (GKF01 and BH1-Sacha) and from three time-equivalent cores through the Hammersley basin in Western Australia. These records reveal similar, apparently synchronous, co-variation between deviations from "typical" Neoarchean Δ36S/Δ33S values and negative δ13COrg values (C-S anomalies). We have interpreted these trends to reflect increased incorporation of 13C-depleted substrates (methane) into sedimentary matter following apparently episodically enhanced methanogenesis in the prelude to the GOE. These records suggest the terminal Neoarchean atmosphere operated in a bi-stable fashion, oscillating between a clear skies and organic-rich hazy state (Zerkle et al., 2010; Izon et al., in review). We speculate that these C-S anomalies reflect enhanced nutrient availability, facilitating the proliferation of an oxygenic photosynthetic/methanogenic biosphere, concomitantly amplifying biogenic CH4 and O2 fluxes and altering atmospheric chemistry. Here we present a new S- and C-isotope data set, derived at unprecedented resolution, encompassing the youngest C-S anomaly identified in core GKF01. These analyses will be combined with Fe-speciation and trace-metal data to elucidate whether atmospheric methane levels were regulated by climatically driven changes in nutrient fluxes to the marine biosphere. Taken together, our research serves as an initial foray to determine how, and why

  12. Solar cosmic ray effects in atmospheric chemistry evidenced from ground- based measurements

    NASA Astrophysics Data System (ADS)

    Shumilov, O.; Kasatkina, E.; Turyansky, V.

    Solar protons with a relatively soft energy spectrum (E<100 MeV) deposit most of their energy in the middle atmosphere above 20 km. Their influence on the atmospheric ozone and odd nitrogen has been studied in details. However, high-energy solar proton events (E>450 MeV) of Ground Level Event (GLE) type can penetrate below 30 km and cause neutron flow enhancement detected by ground-based neutron monitors. Atmospheric effects of such high-energy particles seem to be more pronounced and appeared variations of total content of some atmospheric parameters that can be detected by ground-based devices. It was shown earlier that some GLEs cause considerable ozone total content decreases (up to 25%), or so-called ozone "miniholes" at high latitudes. This work presents ground-based measurements of nitrogen dioxide (NO2) total content made at Murmansk, Kola Peninsula (corrected geomagnetic latitude: 64.8) during and after GLE of 2 May 1998. Nitrogen dioxide was measured by zenith viewing spectrophotometer in wavelength region between 435-450 nm. An increase (about of 20%) in total column of NO2 has been recorded after 2 May 1998 GLE by this facility. Model calculations based on gas phase photochemical theory quantitatively agree with observations. In addition to satellite measurements the information obtained by ground-based devices will be helpful to study atmospheric effects of cosmic ray events. This work was supported by the RFBR grants 01-05-64850 and 01-05-26226).

  13. Probing Titan's Complex Atmospheric Chemistry Using the Atacama Large Millimeter/Submillimeter Array

    NASA Technical Reports Server (NTRS)

    Cordiner, Martin A.; Nixon, Conor; Charnley, Steven B.; Teanby, Nick; Irwin, Pat; Serigano, Joseph; Palmer, Maureen; Kisiel, Zbigniew

    2015-01-01

    Titan is Saturn's largest moon, with a thick (1.45 bar) atmosphere composed primarily of molecular nitrogen and methane. Atmospheric photochemistry results in the production of a wide range of complex organic molecules, including hydrocarbons, nitriles, aromatics and other species of possible pre-biotic relevance. Titan's carbon-rich atmosphere may be analogous to that of primitive terrestrial planets throughout the universe, yet its origin, evolution and complete chemical inventory are not well understood. Here we present spatially-resolved maps of emission from C2H5CN, HNC, HC3N, CH3CN and CH3CCH in Titan's atmosphere, observed using the Atacama Large Millimeter/submillimeter Array (ALMA) in 2012-2013. These data show previously-undetected spatial structures for the observed species and provide the first spectroscopic detection of C2H5CN on Titan. Our maps show spatially resolved peaks in Titan's northern and southern hemispheres, consistent with photochemical production and transport in the upper atmosphere followed by subsidence over the poles. The HNC emission peaks are offset from the polar axis, indicating that Titan's mesosphere may be more longitudinally variable than previously thought.

  14. Probing Titan's Complex Atmospheric Chemistry Using the Atacama Large Millimeter/submillimeter Array

    NASA Astrophysics Data System (ADS)

    Cordiner, Martin A.; Nixon, Conor; Charnley, Steven B.; Teanby, Nick; Irwin, Pat; Serigano, Joseph; Mumma, Michael J.; Palmer, Maureen; Kisiel, Zbigniew; Kuan, Yi-Jehng; Chuang, Yo-Ling

    2015-08-01

    Titan is Saturn's largest moon, with a thick (1.45 bar) atmosphere composed primarily of molecular nitrogen and methane. Atmospheric photochemistry results in the production of a wide range of complex organic molecules, including hydrocarbons, nitriles, aromatics and other species of possible pre-biotic relevance. Titan's carbon-rich atmosphere may be analogous to that of primitive terrestrial planets throughout the universe, yet its origin, evolution and complete chemical inventory are not well understood. Here we present spatially-resolved maps of emission from C2H5CN, HNC, HC3N, CH3CN and CH3CCH in Titan's atmosphere, observed using the Atacama Large Millimeter/submillimeter Array (ALMA) in 2012-2013. These data show previously-undetected spatial structures for the observed species and provide the first spectroscopic detection of C2H5CN on Titan. Our maps show spatially-resolved peaks in Titan's northern and southern hemispheres, consistent with photochemical production and transport in the upper atmosphere followed by subsidence over the poles. The HNC emission peaks are offset from the polar axis, indicating that Titan's mesosphere may be more longitudinally variable than previously thought.

  15. Soil HONO Emissions and Its Potential Impact on the Atmospheric Chemistry and Nitrogen Cycle

    NASA Astrophysics Data System (ADS)

    Su, H.; Chen, C.; Zhang, Q.; Poeschl, U.; Cheng, Y.

    2014-12-01

    Hydroxyl radicals (OH) are a key species in atmospheric photochemistry. In the lower atmosphere, up to ~30% of the primary OH radical production is attributed to the photolysis of nitrous acid (HONO), and field observations suggest a large missing source of HONO. The dominant sources of N(III) in soil, however, are biological nitrification and denitrification processes, which produce nitrite ions from ammonium (by nitrifying microbes) as well as from nitrate (by denitrifying microbes). We show that soil nitrite can release HONO and explain the reported strength and diurnal variation of the missing source. The HONO emissions rates are estimated to be comparable to that of nitric oxide (NO) and could be an important source of atmospheric reactive nitrogen. Fertilized soils appear to be particularly strong sources of HONO. Thus, agricultural activities and land-use changes may strongly influence the oxidizing capacity of the atmosphere. A new HONO-DNDC model was developed to simulate the evolution of HONO emissions in agriculture ecosystems. Because of the widespread occurrence of nitrite-producing microbes and increasing N and acid deposition, the release of HONO from soil may also be important in natural environments, including forests and boreal regions. Reference: Su, H. et al., Soil Nitrite as a Source of Atmospheric HONO and OH Radicals, Science, 333, 1616-1618, 10.1126/science.1207687, 2011.

  16. Establishment of a European digital upper atmosphere server - DIAS project

    NASA Astrophysics Data System (ADS)

    Belehaki, A.; Cander, L.; Zolesi, B.; Bremer, J.; Jurén, C.; Stanislawska, I.; Dialetis, D.; Hatzopoulos, M.

    The goal of DIAS (European digital upper atmosphere server) is to develop a pan-European digital data collection on the state of the upper atmosphere, based on the existing five different historical data collections and on the real-time information provided by all five operating European digital ionospheric stations (digisondes). The operation of such a distributed information server will improve access to digital information on the state of the upper atmosphere over all of Europe, facilitating its use through the development of new value-added products and services such as radio propagation characteristics for the European region, ionospheric maps, alerts and warnings for ionospheric disturbances, useful for large number of users such as HF communication users and navigation systems. Currently, all existing European digisondes operate independently, failing to address the increased demands for comprehensive upper-atmosphere nowcast and forecast services for Europe. DIAS will overcome this problem by operating a server similar to those that exist already for the US. Furthermore, it will contribute to the formation of a network of public research institutes and private sector users that will work to bring out the full potential of this type of information.

  17. Final Technical Report for earmark project "Atmospheric Science Program at the University of Louisville"

    SciTech Connect

    Dowling, Timothy Edward

    2014-02-11

    We have completed a 3-year project to enhance the atmospheric science program at the University of Louisville, KY (est. 2008). The goals were to complete an undergraduate atmospheric science laboratory (Year 1) and to hire and support an assistant professor (Years 2 and 3). Both these goals were met on schedule, and slightly under budget.

  18. Response of lake chemistry to atmospheric deposition and climate in selected Class I wilderness areas in the western United States, 1993-2009

    USGS Publications Warehouse

    Mast, M. Alisa

    2011-01-01

    The U.S. Geological Survey, in cooperation with the U.S. Department of Agriculture Forest Service, Air Resource Management, conducted a study to evaluate long-term trends in lake-water chemistry for 64 high-elevation lakes in selected Class I wilderness areas in Colorado, Idaho, Utah, and Wyoming during 1993 to 2009. Understanding how and why lake chemistry is changing in mountain areas is essential for effectively managing and protecting high-elevation aquatic ecosystems. Trends in emissions, atmospheric deposition, and climate variables (air temperature and precipitation amount) were evaluated over a similar period of record. A main objective of the study was to determine if changes in atmospheric deposition of contaminants in the Rocky Mountain region have resulted in measurable changes in the chemistry of high-elevation lakes. A second objective was to investigate linkages between lake chemistry and air temperature and precipitation to improve understanding of the sensitivity of mountain lakes to climate variability.

  19. Final Report. "Collaborative Project. Contributions of organic compounds to the growth of freshly nucleated atmospheric nanoparticles"

    SciTech Connect

    Smith, James N

    2015-12-23

    This is the final technical report for the portion of the project that took place at the National Center for Atmospheric Research, which covers approximately the first year of the three-year project. During this time we focused primarily on analysis and modeling of DOE-funded observations as well as preparation for laboratory studies of individual processes that contribute to atmospheric new particle formation.

  20. Evaluated kinetic and photochemical data for atmospheric chemistry: Volume VI - heterogeneous reactions with liquid substrates

    NASA Astrophysics Data System (ADS)

    Ammann, M.; Cox, R. A.; Crowley, J. N.; Jenkin, M. E.; Mellouki, A.; Rossi, M. J.; Troe, J.; Wallington, T. J.

    2012-12-01

    This article, the sixth in the ACP journal series, presents data evaluated by the IUPAC Task Group on Atmospheric Chemical Kinetic Data Evaluation. It covers the heterogeneous processes involving liquid particles present in the atmosphere, for which uptake coefficients and adsorption parameters have been presented on the IUPAC website since 2009. The article consists of an introduction and guide to the evaluation, giving a unifying framework for parameterisation of atmospheric heterogeneous processes. We provide summary sheets containing the recommended uptake parameters for the evaluated processes. The experimental data on which the recommendations are based are provided in data sheets in separate appendices for the four surfaces considered: liquid water, deliquesced halide salts, other aqueous electrolytes and sulfuric acid.

  1. Evaluated kinetic and photochemical data for atmospheric chemistry: Volume VI - heterogeneous reactions with liquid substrates

    NASA Astrophysics Data System (ADS)

    Ammann, M.; Cox, R. A.; Crowley, J. N.; Jenkin, M. E.; Mellouki, A.; Rossi, M. J.; Troe, J.; Wallington, T. J.

    2013-08-01

    This article, the sixth in the ACP journal series, presents data evaluated by the IUPAC Task Group on Atmospheric Chemical Kinetic Data Evaluation. It covers the heterogeneous processes involving liquid particles present in the atmosphere with an emphasis on those relevant for the upper troposphere/lower stratosphere and the marine boundary layer, for which uptake coefficients and adsorption parameters have been presented on the IUPAC website since 2009. The article consists of an introduction and guide to the evaluation, giving a unifying framework for parameterisation of atmospheric heterogeneous processes. We provide summary sheets containing the recommended uptake parameters for the evaluated processes. The experimental data on which the recommendations are based are provided in data sheets in separate appendices for the four surfaces considered: liquid water, deliquesced halide salts, other aqueous electrolytes and sulfuric acid.

  2. O3-N2O correlations from the Atmospheric Chemistry Experiment: Revisiting a diagnostic of transport and chemistry in the stratosphere

    NASA Astrophysics Data System (ADS)

    Hegglin, Michaela I.; Shepherd, Theodore G.

    2007-10-01

    Our knowledge of stratospheric O3-N2O correlations is extended, and their potential for model-measurement comparison assessed, using data from the Atmospheric Chemistry Experiment (ACE) satellite and the Canadian Middle Atmosphere Model (CMAM). ACE provides the first comprehensive data set for the investigation of interhemispheric, interseasonal, and height-resolved differences of the O3-N2O correlation structure. By subsampling the CMAM data, the representativeness of the ACE data is evaluated. In the middle stratosphere, where the correlations are not compact and therefore mainly reflect the data sampling, joint probability density functions provide a detailed picture of key aspects of transport and mixing, but also trace polar ozone loss. CMAM captures these important features, but exhibits a displacement of the tropical pipe into the Southern Hemisphere (SH). Below about 21 km, the ACE data generally confirm the compactness of the correlations, although chemical ozone loss tends to destroy the compactness during late winter/spring, especially in the SH. This allows a quantitative comparison of the correlation slopes in the lower and lowermost stratosphere (LMS), which exhibit distinct seasonal cycles that reveal the different balances between diabatic descent and horizontal mixing in these two regions in the Northern Hemisphere (NH), reconciling differences found in aircraft measurements, and the strong role of chemical ozone loss in the SH. The seasonal cycles are qualitatively well reproduced by CMAM, although their amplitude is too weak in the NH LMS. The correlation slopes allow a "chemical" definition of the LMS, which is found to vary substantially in vertical extent with season.

  3. A fast, parameterized model of upper atmospheric ionization rates, chemistry, and conductivity

    NASA Astrophysics Data System (ADS)

    McGranaghan, Ryan; Knipp, Delores J.; Solomon, Stanley C.; Fang, Xiaohua

    2015-06-01

    Rapid specification of ionization rates and ion densities in the upper atmosphere is essential when many evaluations of the atmospheric state must be performed, as in global studies or analyses of on-orbit satellite data. Though many models of the upper atmosphere perform the necessary specification, none provide the flexibility of computational efficiency, high accuracy, and complete specification. We introduce a parameterized, updated, and extended version of the GLobal AirglOW (GLOW) model, called GLOWfast, that significantly reduces computation time and provides comparable accuracy in upper atmospheric ionization, densities, and conductivity. We extend GLOW capabilities by (1) implementing the nitric oxide empirical model, (2) providing a new model component to calculate height-dependent conductivity profiles from first principles for the 80-200 km region, and (3) reducing computation time. The computational improvement is achieved by replacing the full, two-stream electron transport algorithm with two parameterizations: (1) photoionization (QRJ from Solomon and Qian and (2) electron impact ionization (F0810 from Fang et al.). We find that GLOWfast accurately reproduces ionization rates, ion and electron densities, and Pedersen and Hall conductivities independent of the background atmospheric state and input solar and auroral activity. Our results suggest that GLOWfast may be even more appropriate for low characteristic energy auroral conditions. We demonstrate in a suite of 3028 case studies that GLOWfast can be used to rapidly calculate the ionization of the upper atmosphere with few limitations on background and input conditions. We support these results through comparisons with electron density profiles from COSMIC.

  4. HOCl chemistry in the Antarctic stratospheric vortex 2002, as observed with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS)

    NASA Astrophysics Data System (ADS)

    von Clarmann, T.; Glatthor, N.; Ruhnke, R.; Stiller, G. P.; Kirner, O.; Reddmann, T.; Höpfner, M.; Kellmann, S.; Kouker, W.; Linden, A.; Funke, B.

    2008-11-01

    In the 2002 Antarctic polar vortex enhanced HOCl mixing ratios were detected by the Michelson Interferometer for Passive Atmospheric Sounding both at altitudes of around 35 km, where HOCl abundances are ruled by gas phase chemistry and at around 24 km, which belongs to the altitude domain where heterogeneous chlorine chemistry is relevant. At altitudes of 33 to 40 km, where in midlatitudinal and tropical atmospheres peak HOCl mixing ratios significantly above 0.2 ppbv (in terms of daily mean values) are observed, polar vortex HOCl mixing ratios were found to be around 0.14 ppbv as long as the polar vortex was intact, centered at the pole, and thus received relatively little sunlight. After deformation and displacement of the polar vortex in the course of a major warming, ClO rich vortex air was more exposed to sunlight, where enhanced HOx abundances led to largely increased HOCl mixing ratios (up to 0.3 ppbv), exceeding typical midlatitudinal and tropical amounts significantly. The HOCl increase was preceded by an increase of ClO. Model runs could reproduce these measurements only when the Stimpfle et al. (1979) rate constant for the reaction ClO+HO2→HOCl+O2 was used but not with the current JPL recommendation. At an altitude of 24 km, HOCl mixing ratios of up to 0.15 ppbv were detected. This HOCl enhancement, which is already visible in 18 September data, is attributed to heterogeneous chemistry, which is in agreement with observations of polar stratospheric clouds. Comparison with a model run where no polar stratospheric clouds appeared during the observation period suggests that a significant part of HOCl was generated from ClO rather than directly via heterogeneous reaction. Excess ClO and HOCl in the measurements is attributed to ongoing heterogeneous chemistry which is not reproduced by the model. In the following days, a decay of HOCl abundances was observed and on 11 October, polar vortex mean daytime mixing ratios were only 0.03 ppbv.

  5. HOCl chemistry in the Antarctic Stratospheric Vortex 2002, as observed with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS)

    NASA Astrophysics Data System (ADS)

    von Clarmann, T.; Glatthor, N.; Ruhnke, R.; Stiller, G. P.; Kirner, O.; Reddmann, T.; Höpfner, M.; Kellmann, S.; Kouker, W.; Linden, A.; Funke, B.

    2009-03-01

    In the 2002 Antarctic polar vortex enhanced HOCl mixing ratios were detected by the Michelson Interferometer for Passive Atmospheric Sounding both at altitudes of around 35 km (1000 K potential temperature), where HOCl abundances are ruled by gas phase chemistry and at around 18-24 km (475-625 K), which belongs to the altitude domain where heterogeneous chlorine chemistry is relevant. At altitudes of 33 to 40 km polar vortex HOCl mixing ratios were found to be around 0.14 ppbv as long as the polar vortex was intact, centered at the pole, and thus received relatively little sunlight. This is the altitude region where in midlatitudinal and tropic atmospheres peak HOCl mixing ratios significantly above 0.2 ppbv (in terms of daily mean values) are observed. After deformation and displacement of the polar vortex in the course of a major warming, ClO-rich vortex air was more exposed to sunlight, where enhanced HOx abundances led to largely increased HOCl mixing ratios (up to 0.3 ppbv), exceeding typical midlatitudinal and tropical amounts significantly. The HOCl increase was preceded by an increase of ClO. Model runs could reproduce these measurements only when the Stimpfle et al. (1979) rate constant for the reaction ClO+HO2→HOCl+O2 was used but not with the current JPL recommendation. At an altitude of 24 km, HOCl mixing ratios of up to 0.15 ppbv were detected. This HOCl enhancement, which is already visible in 18 September data, is attributed to heterogeneous chemistry, which is in agreement with observations of polar stratospheric clouds. The measurements were compared to a model run where no polar stratospheric clouds appeared during the observation period. The fact that HOCl still was produced in the model run suggests that a significant part of HOCl was generated from ClO rather than directly via heterogeneous reaction. Excess ClO, lower ClONO2 and earlier loss of HOCl in the measurements are attributed to ongoing heterogeneous chemistry which is not reproduced

  6. Response of lake chemistry to changes in atmospheric deposition and climate in three high-elevation wilderness areas of Colorado

    USGS Publications Warehouse

    Mast, M.A.; Turk, J.T.; Clow, D.W.; Campbell, D.H.

    2011-01-01

    Trends in precipitation chemistry and hydrologic and climatic data were examined as drivers of long-term changes in the chemical composition of high-elevation lakes in three wilderness areas in Colorado during 1985-2008. Sulfate concentrations in precipitation decreased at a rate of -0.15 to -0.55 ??eq/l/year at 10 high-elevation National Atmospheric Deposition Program stations in the state during 1987-2008 reflecting regional reductions in SO2 emissions. In lakes where sulfate is primarily derived from atmospheric inputs, sulfate concentrations also decreased although the rates generally were less, ranging from -0.12 to -0.27 ??eq/l/year. The similarity in timing and sulfur isotopic data support the hypothesis that decreases in atmospheric deposition are driving the response of high-elevation lakes in some areas of the state. By contrast, in lakes where sulfate is derived primarily from watershed weathering sources, sulfate concentrations showed sharp increases during 1985-2008. Analysis of long-term climate records indicates that annual air temperatures have increased between 0.45 and 0.93??C per decade throughout most mountainous areas of Colorado, suggesting climate as a factor. Isotopic data reveal that sulfate in these lakes is largely derived from pyrite, which may indicate climate warming is preferentially affecting the rate of pyrite weathering. ?? 2010 US Government.

  7. Response of lake chemistry to changes in atmospheric deposition and climate in three high-elevation wilderness areas of Colorado

    USGS Publications Warehouse

    Mast, M. Alisa; Turk, John T.; Clow, David W.; Campbell, Donald D.

    2011-01-01

    Trends in precipitation chemistry and hydrologic and climatic data were examined as drivers of long-term changes in the chemical composition of high-elevation lakes in three wilderness areas in Colorado during 1985-2008. Sulfate concentrations in precipitation decreased at a rate of -0.15 to -0.55 μeq/l/year at 10 high-elevation National Atmospheric Deposition Program stations in the state during 1987-2008 reflecting regional reductions in SO2 emissions. In lakes where sulfate is primarily derived from atmospheric inputs, sulfate concentrations also decreased although the rates generally were less, ranging from -0.12 to -0.27 μeq/l/year. The similarity in timing and sulfur isotopic data support the hypothesis that decreases in atmospheric deposition are driving the response of high-elevation lakes in some areas of the state. By contrast, in lakes where sulfate is derived primarily from watershed weathering sources, sulfate concentrations showed sharp increases during 1985-2008. Analysis of long-term climate records indicates that annual air temperatures have increased between 0.45 and 0.93°C per decade throughout most mountainous areas of Colorado, suggesting climate as a factor. Isotopic data reveal that sulfate in these lakes is largely derived from pyrite, which may indicate climate warming is preferentially affecting the rate of pyrite weathering.

  8. The Atmospheric Circulation of a Nine-hot-Jupiter Sample: Probing Circulation and Chemistry over a Wide Phase Space

    NASA Astrophysics Data System (ADS)

    Kataria, Tiffany; Sing, David K.; Lewis, Nikole K.; Visscher, Channon; Showman, Adam P.; Fortney, Jonathan J.; Marley, Mark S.

    2016-04-01

    We present results from an atmospheric circulation study of nine hot Jupiters that compose a large transmission spectral survey using the Hubble and Spitzer Space Telescopes. These observations exhibit a range of spectral behavior over optical and infrared wavelengths, suggesting diverse cloud and haze properties in their atmospheres. By utilizing the specific system parameters for each planet, we naturally probe a wide phase space in planet radius, gravity, orbital period, and equilibrium temperature. First, we show that our model “grid” recovers trends shown in traditional parametric studies of hot Jupiters, particularly equatorial superrotation and increased day–night temperature contrast with increasing equilibrium temperature. We show how spatial temperature variations, particularly between the dayside and nightside and west and east terminators, can vary by hundreds of kelvin, which could imply large variations in Na, K, CO and {{{CH}}}4 abundances in those regions. These chemical variations can be large enough to be observed in transmission with high-resolution spectrographs, such as ESPRESSO on VLT, METIS on the E-ELT, or MIRI and NIRSpec aboard JWST. We also compare theoretical emission spectra generated from our models to available Spitzer eclipse depths for each planet and find that the outputs from our solar-metallicity, cloud-free models generally provide a good match to many of the data sets, even without additional model tuning. Although these models are cloud-free, we can use their results to understand the chemistry and dynamics that drive cloud formation in their atmospheres.

  9. Studies of the chemistry of vibrationally and electronically excited species in planetary upper atmospheres

    NASA Technical Reports Server (NTRS)

    Fox, J. L.

    1984-01-01

    The vibrational distribution of O2(+) in the atmospheres of Venus and Mars was investigated to compare with analogous values in the Earth's atmosphere. The dipole moment of the Z(2) Pi sub u - X(2) Pi sub g transition of O2(+) is calculated as a function of internuclear distance. The band absorption oscillator strengths and band transition probabilities of the second negative system are derived. The vibrational distribution of O2(+) in the ionosphere of Venus is calculated for a model based on data from the Pioneer Venus neutral mass spectrometer.

  10. Atmospheric chemistry suite (ACS): a set of infrared spectrometers for atmospheric measurements on board ExoMars trace gas orbiter

    NASA Astrophysics Data System (ADS)

    Korablev, Oleg; Grigoriev, Alexei V.; Trokhimovsky, Alexander; Ivanov, Yurii S.; Moshkin, Boris; Shakun, Alexei; Dziuban, Ilia; Kalinnikov, Yurii K.; Montmessin, Franck

    2013-09-01

    The ACS package for ExoMars Trace Gas Orbiter is a part of Russian contribution to ExoMars ESA-Roscosmos mission. On the Orbiter it complements NOMAD investigation and is intended to recover in much extent the science lost with the cancellation of NASA MATMOS and EMCS infrared sounders. ACS includes three separate spectrometers, sharing common mechanical, electrical, and thermal interfaces. NIR is a versatile spectrometer for the spectral range of 0.7-1.6 μm with resolving power of ~20000. It is conceived on the principle of RUSALKA/ISS or SOIR/Venus Express experiments combining an echelle spectrometer and an AOTF (Acousto-Optical Tuneable Filter) for order selection. Up to 8 diffraction orders, each 10-20 nm wide can be measured in one sequence record. NIR will be operated principally in nadir, but also in solar occultations, and possibly on the limb. MIR is a high-resolution echelle instrument exclusively dedicated to solar occultation measurements in the range of 2.2-4.4 μm targeting the resolving power of 50000. The order separation is done by means of a steerable grating cross-disperser, allowing instantaneous coverage of up to 300-nm range of the spectrum for one or two records per second. MIR is dedicated to sensitive measurements of trace gases, approaching MATMOS detection thresholds for many species. TIRVIM is a 2- inch double pendulum Fourier-transform spectrometer for the spectral range of 1.7-17 μm with apodized resolution varying from 0.2 to 1.6 cm-1. TIRVIM is primarily dedicated to monitoring of atmospheric temperature and aerosol state in nadir, and would contribute in solar occultation to detection/reducing of upper limits of some components absorbing beyond 4 μm, complementing MIR and NOMAD. Additionally, TIRVIM targets the methane mapping in nadir, using separate detector optimized for 3.3-μm range. The concept of the instrument and in more detail the optical design and the expected parameters of its three parts, channel by channel are

  11. Observations of peroxyacetyl nitrate (PAN) in the upper troposphere by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS)

    NASA Astrophysics Data System (ADS)

    Tereszchuk, K. A.; Moore, D. P.; Harrison, J. J.; Boone, C. D.; Park, M.; Remedios, J. J.; Randel, W. J.; Bernath, P. F.

    2013-01-01

    Peroxyacetyl nitrate (CH3CO·O2NO2, abbreviated as PAN) is a trace molecular species present in the troposphere and lower stratosphere due primarily to pollution from fuel combustion and the pyrogenic outflows from biomass burning. In the lower troposphere, PAN has a relatively short life-time and is principally destroyed within a few hours through thermolysis, but it can act as a reservoir and carrier of NOx in the colder temperatures of the upper troposphere where UV photolysis becomes the dominant loss mechanism. Pyroconvective updrafts from large biomass burning events can inject PAN into the upper troposphere and lower stratosphere (UTLS), providing a means for the long-range transport of NOx. Given the extended lifetimes at these higher altitudes, PAN is readily detectable via satellite remote sensing. A new PAN data product is now available for the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) Version 3.0 data set. We report measurements of PAN in Boreal biomass burning plumes recorded during the Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites (BORTAS) campaign. The retrieval method employed and errors analysis are described in full detail. The retrieved volume mixing ratio (VMR) profiles are compared to coincident measurements made by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instrument on the European Space Agency (ESA) ENVIronmental SATellite (ENVISAT). Three ACE-FTS occultations containing measurements of Boreal biomass burning outflows, recorded during BORTAS, were identified as having coincident measurements with MIPAS. In each case, the MIPAS measurements demonstrated good agreement with the ACE-FTS VMR profiles for PAN. The ACE-FTS PAN data set is used to obtain zonal mean distributions of seasonal averages from ~5 to 20 km. A strong seasonality is clearly observed for PAN concentrations in the global UTLS. Since the

  12. Toward Solutions: The Work of the Chemistry Action-Research Group. Learning in Science Project. Working Paper No. 35.

    ERIC Educational Resources Information Center

    Osborne, Roger; And Others

    In the action-research phase of the Learning in Science Project, four groups of people worked on problems identified in the project's second (in-depth) phase. The Chemistry Action-Research Group considered problems related to the teaching and learning of ideas associated with particles and physical/chemical changes. Based on findings during the…

  13. Sol-Gel Application for Consolidating Stone: An Example of Project-Based Learning in a Physical Chemistry Lab

    ERIC Educational Resources Information Center

    de los Santos, Desiree´ M.; Montes, Antonio; Sa´nchez-Coronilla, Antonio; Navas, Javier

    2014-01-01

    A Project Based Learning (PBL) methodology was used in the practical laboratories of the Advanced Physical Chemistry department. The project type proposed simulates "real research" focusing on sol-gel synthesis and the application of the obtained sol as a stone consolidant. Students were divided into small groups (2 to 3 students) to…

  14. Indication of drier periods on Mars from the chemistry and mineralogy of atmospheric dust.

    PubMed

    Goetz, Walter; Bertelsen, Preben; Binau, Charlotte S; Gunnlaugsson, Haraldur P; Hviid, Stubbe F; Kinch, Kjartan M; Madsen, Daniel E; Madsen, Morten B; Olsen, Malte; Gellert, Ralf; Klingelhöfer, Göstar; Ming, Douglas W; Morris, Richard V; Rieder, Rudolf; Rodionov, Daniel S; de Souza, Paulo A; Schröder, Christian; Squyres, Steve W; Wdowiak, Tom; Yen, Albert

    2005-07-01

    The ubiquitous atmospheric dust on Mars is well mixed by periodic global dust storms, and such dust carries information about the environment in which it once formed and hence about the history of water on Mars. The Mars Exploration Rovers have permanent magnets to collect atmospheric dust for investigation by instruments on the rovers. Here we report results from Mössbauer spectroscopy and X-ray fluorescence of dust particles captured from the martian atmosphere by the magnets. The dust on the magnets contains magnetite and olivine; this indicates a basaltic origin of the dust and shows that magnetite, not maghemite, is the mineral mainly responsible for the magnetic properties of the dust. Furthermore, the dust on the magnets contains some ferric oxides, probably including nanocrystalline phases, so some alteration or oxidation of the basaltic dust seems to have occurred. The presence of olivine indicates that liquid water did not play a dominant role in the processes that formed the atmospheric dust. PMID:16001062

  15. ASSESSMENT OF CROP LOSS FROM AIR POLLUTANTS: METEOROLOGY-ATMOSPHERIC CHEMISTRY AND LONG RANGE TRANSPORT

    EPA Science Inventory

    Ozone is a secondary pollutant with many distinctive characteristics in respect to its sources and modes of formation within regions of the troposphere and in the stratosphere. The scales of intermediate and longer range transport influencing the atmospheric distribution of O3 wi...

  16. Mars Atmospheric Oxidant Sensor (MAOS): An In-Situ Heterogeneous Chemistry Analysis

    NASA Technical Reports Server (NTRS)

    Zent, A. P.; Quinn, R. C.; Grunthaner, F. J.; Hecht, M. H.; Buehler, M. G.; McKay, C. P.; Ricco, A. J.

    2002-01-01

    We describe a chemometric array sensor, the Mars Atmospheric Oxidant Sensor (MAOS) that is designed to measure the oxidation rate of thin films on the martian surface. MAOS will discriminate among leading hypotheses for oxidant production. Additional information is contained in the original extended abstract.

  17. Analysis of nitrate in the snow and atmosphere at Summit, Greenland: Chemistry and transport

    NASA Astrophysics Data System (ADS)

    Fibiger, Dorothy L.; Dibb, Jack E.; Chen, Dexian; Thomas, Jennie L.; Burkhart, John F.; Huey, L. Gregory; Hastings, Meredith G.

    2016-05-01

    As a major sink of atmospheric nitrogen oxides (NOx = NO + NO2), nitrate (NO3-) in polar snow can reflect the long-range transport of NOx and related species (e.g., peroxyacetyl nitrate). On the other hand, because NO3- in snow can be photolyzed, potentially producing gas phase NOx locally, NO3- in snow (and thus, ice) may reflect local processes. Here we investigate the relationship between local atmospheric composition at Summit, Greenland (72°35'N, 38°25'W) and the isotopic composition of NO3- to determine the degree to which local processes influence atmospheric and snow NO3-. Based on snow and atmospheric observations during May-June 2010 and 2011, we find no connection between the local atmospheric concentrations of a suite of gases (BrO, NO, NOy, HNO3, and nitrite (NO2-)) and the NO3- isotopic composition or concentration in snow. This suggests that (1) the snow NO3- at Summit is primarily derived from long-range transport and (2) this NO3- is largely preserved in the snow. Additionally, three isotopically distinct NO3- sources were found to be contributing to the NO3- in the snow at Summit during both 2010 and 2011. Through the complete isotopic composition of NO3-, we suggest that these sources are local anthropogenic particulate NO3- from station activities (δ15N = 16‰, Δ17O = 4‰, and δ18O = 23‰), NO3- formed from midlatitude NOx (δ15N = -10‰, Δ17O = 29‰, δ18O = 78‰) and a NO3- source that is possibly influenced by or derived from stratospheric ozone NO3- (δ15N = 5‰, Δ17O = 39‰, δ18O = 100‰).

  18. 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.

  19. A modelling study of the atmospheric chemistry of DMS using the global model, STOCHEM-CRI

    NASA Astrophysics Data System (ADS)

    Khan, M. A. H.; Gillespie, S. M. P.; Razis, B.; Xiao, P.; Davies-Coleman, M. T.; Percival, C. J.; Derwent, R. G.; Dyke, J. M.; Ghosh, M. V.; Lee, E. P. F.; Shallcross, D. E.

    2016-02-01

    The tropospheric chemistry of dimethylsulfide (DMS) is investigated using a global three-dimensional chemical transport model, STOCHEM with the CRIv2-R5 chemistry scheme. The tropospheric distribution of DMS and its removal at the surface by OH abstraction, OH addition, NO3 oxidation, and BrO oxidation is modelled. The study shows that the lifetime and global burden of DMS is ca. 1.2 days and 98 Gg S, respectively. Inclusion of BrO oxidation resulted in a reduction of the lifetime (1.0 day) and global burden (83 Gg S) of DMS showing that this reaction is important in the DMS budget. The percentage contribution of BrO oxidation to the total removal of DMS is found to be only 7.9% that is considered a lower limit because the study does not include an inorganic source of bromine from sea-salt. BrO oxidation contributed significantly in the high latitudes of the southern hemisphere (SH). Inclusion of DMS removal by Cl2 showed that potentially a large amount of DMS is removed via this reaction specifically in the remote SH oceans, depending on the flux of Cl2 from the Southern Ocean. Model DMS levels are evaluated against measurement data from six different sites around the globe. The model predicted the correct seasonal cycle for DMS at all locations and correlated well with measurement data for most of the periods.

  20. Large uncertainties in projected European summer warming and drying due to ocean-atmosphere and land-atmosphere interactions

    NASA Astrophysics Data System (ADS)

    Selten, Frank M.; Bintanja, Richard; Vautard, Robert; van den Hurk, Bart; Haarsma, Rein

    2016-04-01

    Europe is among the regions with the highest summer warming rates and largest spread in the projected warming in the latest CMIP5 climate model projections. The end-of-this-century summer warming under the RCP8.5 scenario ranges from about 3 to 9 degrees. Why do models disagree so much on the response of the summer climate in Europe to an increase in greenhouse gas concentrations? The origin of these uncertainties is traced through a combination of statistical analyses, theoretical arguments and additional model simulations to both the uncertain response of the ocean circulation to the warming and land-atmosphere interactions in continental Europe.

  1. Development of ground support equipment for the NPS ionospheric spectroscopy and atmospheric chemistry (ISAAC) ultraviolet spectrograph. Master`s thesis

    SciTech Connect

    Fragiskos, L.

    1995-06-01

    This thesis details the design of Ground Support Equipment (GSE) for the Naval Postgraduate School`s Ionospheric Spectroscopy and Atmospheric Chemistry (ISAAC) Ultraviolet Spectrograph. ISAAC is one of the several experiments to be flown on the Advanced Research and Global Observation Satellite (ARGOS) in 1996. The GSE consists of several software programs written in LabVIEW. These programs simulate the timing signals that ISAAC will receive from the satellite bus. In addition, the programs acquire serial data from ISAAC, perform a serial to parallel conversion and display the resulting spectra. The GSE will allow testing of the spectrograph prior to the interface with the satellite bus. Although the complete flight instrument is not yet available for testing, this thesis describes how the GSE-to-ISAAC interface will be made and how it should be operated. Finally, some hardware/software incompatibilities are identified.

  2. NCAR (National Center for Atmospheric Research) master mechanism of the gas phase chemistry, version 2.0

    NASA Astrophysics Data System (ADS)

    Madronich, Sasha; Calvert, Jack G.

    1989-05-01

    The NCAR Master Mechanism of the Gas Phase Chemistry is an explicit, highly detailed mechanism describing the gas phase chemical transformations that may occur in the atmosphere. The initial version (Version 1.0) was developed in 1984. Since that time, the number of chemical reactions considered has increased from 1964 to 4930. Most of the new reactions concern the photooxidation of hydrocarbons. Directly measured kinetic and mechanistic data were updated. For many reactions no direct kinetic or mechanistic measurements exist. For such reactions, similarity and analogy to known processes were used tio derive both product identity and the rate constants. One major departure from the Version 1.0 is the inclusion of the permutation reactions of organic peroxy radicals. These reactions are handled using an exact counter method described by Madronich and Calvert (1989).

  3. Heterogeneous Atmospheric Chemistry of Lead Oxide Particles with Nitrogen Dioxide Increases Lead Solubility: Environmental and Health Implications

    PubMed Central

    Baltrusaitis, Jonas; Chen, Haihan; Rubasinghege, Gayan

    2012-01-01

    Heterogeneous chemistry of nitrogen dioxide with lead-containing particles is investigated to better understand lead metal mobilization in the environment. In particular, PbO particles, a model lead-containing compound due to its wide spread presence as a component of lead paint and as naturally occurring minerals, massicot and litharge, are exposed to nitrogen dioxide at different relative humidity. X-ray photoelectron spectroscopy (XPS) shows that upon exposure to nitrogen dioxide the surface of PbO particles react to form adsorbed nitrates and lead nitrate thin films with the extent of formation of nitrate relative humidity dependent. Surface adsorbed nitrate increases the amount of dissolved lead. These reacted particles are found to have an increase in the amount of lead that dissolves in aqueous suspensions at circumneutral pH compared to unreacted particles. These results point to the potential importance and impact that heterogeneous chemistry with trace atmospheric gases can have on increasing solubility and therefore the mobilization of heavy metals, such as lead, in the environment. This study also show that surface intermediates, such as adsorbed nitrates, that form can yield higher concentrations of lead in water systems. In the environment, these water systems can include drinking water, ground water, estuaries and lakes. PMID:23057678

  4. Reactions of substituted benzene anions with N and O atoms: Chemistry in Titan's upper atmosphere and the interstellar medium

    NASA Astrophysics Data System (ADS)

    Wang, Zhe-Chen; Bierbaum, Veronica M.

    2016-06-01

    The likely existence of aromatic anions in many important extraterrestrial environments, from the atmosphere of Titan to the interstellar medium (ISM), is attracting increasing attention. Nitrogen and oxygen atoms are also widely observed in the ISM and in the ionospheres of planets and moons. In the current work, we extend previous studies to explore the reactivity of prototypical aromatic anions (deprotonated toluene, aniline, and phenol) with N and O atoms both experimentally and computationally. The benzyl and anilinide anions both exhibit slow associative electron detachment (AED) processes with N atom, and moderate reactivity with O atom in which AED dominates but ionic products are also formed. The reactivity of phenoxide is dramatically different; there is no measurable reaction with N atom, and the moderate reactivity with O atom produces almost exclusively ionic products. The reaction mechanisms are studied theoretically by employing density functional theory calculations, and spin conversion is found to be critical for understanding some product distributions. This work provides insight into the rich gas-phase chemistry of aromatic ion-atom reactions and their relevance to ionospheric and interstellar chemistry.

  5. Reactions of substituted benzene anions with N and O atoms: Chemistry in Titan's upper atmosphere and the interstellar medium.

    PubMed

    Wang, Zhe-Chen; Bierbaum, Veronica M

    2016-06-01

    The likely existence of aromatic anions in many important extraterrestrial environments, from the atmosphere of Titan to the interstellar medium (ISM), is attracting increasing attention. Nitrogen and oxygen atoms are also widely observed in the ISM and in the ionospheres of planets and moons. In the current work, we extend previous studies to explore the reactivity of prototypical aromatic anions (deprotonated toluene, aniline, and phenol) with N and O atoms both experimentally and computationally. The benzyl and anilinide anions both exhibit slow associative electron detachment (AED) processes with N atom, and moderate reactivity with O atom in which AED dominates but ionic products are also formed. The reactivity of phenoxide is dramatically different; there is no measurable reaction with N atom, and the moderate reactivity with O atom produces almost exclusively ionic products. The reaction mechanisms are studied theoretically by employing density functional theory calculations, and spin conversion is found to be critical for understanding some product distributions. This work provides insight into the rich gas-phase chemistry of aromatic ion-atom reactions and their relevance to ionospheric and interstellar chemistry. PMID:27276954

  6. Impacts of aerosols on the chemistry of atmospheric trace gases: a case study of peroxides and HO2 radicals

    NASA Astrophysics Data System (ADS)

    Liang, H.; Chen, Z. M.; Huang, D.; Zhao, Y.; Li, Z. Y.

    2013-06-01

    Field measurements of atmospheric peroxides were obtained during the summer on two consecutive years over urban Beijing, and focused on the impacts of aerosols on the chemistry of peroxide compounds and hydroperoxyl radicals (HO2). The major peroxides were determined to be hydrogen peroxide (H2O2), methyl hydroperoxide (MHP), and peroxyacetic acid (PAA). A negative correlation was found between H2O2 and PAA in rainwater, providing evidence for a conversion between H2O2 and PAA in the aqueous phase. A standard gas phase chemistry model based on the NCAR Master Mechanism provided a good reproduction of the observed H2O2 profile on non-haze days but greatly overpredicted the H2O2 level on haze days. We attribute this overprediction to the reactive uptake of HO2 by the aerosols, since there was greatly enhanced aerosol loading and aerosol liquid water content on haze days. The discrepancy between the observed and modeled H2O2 can be diminished by adding to the model a newly proposed transition metal ion catalytic mechanism of HO2 in aqueous aerosols. This confirms the importance of the aerosol uptake of HO2 and the subsequent aqueous phase reactions in the reduction of H2O2. The closure of HO2 and H2O2 between the gas and aerosol phases suggests that the aerosols do not have a net reactive uptake of H2O2, because the conversion of HO2 to H2O2 on aerosols compensates for the H2O2 loss. Laboratory studies for the aerosol uptake of H2O2 in the presence of HO2 are urgently required to better understand the aerosol uptake of H2O2 in the real atmosphere.

  7. Impacts of aerosols on the chemistry of atmospheric trace gases: a case study of peroxides and HO2 radicals

    NASA Astrophysics Data System (ADS)

    Liang, H.; Chen, Z. M.; Huang, D.; Zhao, Y.; Li, Z. Y.

    2013-11-01

    Field measurements of atmospheric peroxides were obtained during the summer on two consecutive years over urban Beijing, which highlighted the impacts of aerosols on the chemistry of peroxide compounds and hydroperoxyl radicals (HO2). The major peroxides were determined to be hydrogen peroxide (H2O2), methyl hydroperoxide (MHP), and peroxyacetic acid (PAA). A negative correlation was found between H2O2 and PAA in rainwater, providing evidence for a conversion between H2O2 and PAA in the aqueous phase. A standard gas phase chemistry model based on the NCAR Master Mechanism provided a good reproduction of the observed H2O2 profile on non-haze days but greatly overpredicted the H2O2 level on haze days. We attribute this overprediction to the reactive uptake of HO2 by the aerosols, since there was greatly enhanced aerosol loading and aerosol liquid water content on haze days. The discrepancy between the observed and modeled H2O2 can be diminished by adding to the model a newly proposed transition metal ion catalytic mechanism of HO2 in aqueous aerosols. This confirms the importance of the aerosol uptake of HO2 and the subsequent aqueous phase reactions in the reduction of H2O2. The closure of HO2 and H2O2 between the gas and aerosol phases suggests that the aerosols do not have a net reactive uptake of H2O2, because the conversion of HO2 to H2O2 on aerosols compensates for the H2O2 loss. Laboratory studies for the aerosol uptake of H2O2 in the presence of HO2 are urgently required to better understand the aerosol uptake of H2O2 in the real atmosphere.

  8. Reactions of Azine Anions with Nitrogen and Oxygen Atoms: Implications for Titan's Upper Atmosphere and Interstellar Chemistry.

    PubMed

    Wang, Zhe-Chen; Cole, Callie A; Demarais, Nicholas J; Snow, Theodore P; Bierbaum, Veronica M

    2015-08-26

    Azines are important in many extraterrestrial environments, from the atmosphere of Titan to the interstellar medium. They have been implicated as possible carriers of the diffuse interstellar bands in astronomy, indicating their persistence in interstellar space. Most importantly, they constitute the basic building blocks of DNA and RNA, so their chemical reactivity in these environments has significant astrobiological implications. In addition, N and O atoms are widely observed in the ISM and in the ionospheres of planets and moons. However, the chemical reactions of molecular anions with abundant interstellar and atmospheric atomic species are largely unexplored. In this paper, gas-phase reactions of deprotonated anions of benzene, pyridine, pyridazine, pyrimidine, pyrazine, and s-triazine with N and O atoms are studied both experimentally and computationally. In all cases, the major reaction channel is associative electron detachment; these reactions are particularly important since they control the balance between negative ions and free electron densities. The reactions of the azine anions with N atoms exhibit larger rate constants than reactions of corresponding chain anions. The reactions of azine anions with O atoms are even more rapid, with complex product patterns for different reactants. The mechanisms are studied theoretically by employing density functional theory; spin conversion is found to be important in determining some product distributions. The rich gas-phase chemistry observed in this work provides a better understanding of ion-atom reactions and their contributions to ionospheric chemistry as well as the chemical processing that occurs in the boundary layers between diffuse and dense interstellar clouds. PMID:26281019

  9. Atmospheric deposition and corresponding variability of stemflow chemistry across temporal scales in a mid-Atlantic broadleaved deciduous forest

    NASA Astrophysics Data System (ADS)

    Levia, Delphis F.; Van Stan, John T.; Siegert, Courtney M.; Inamdar, Shreeram P.; Mitchell, Myron J.; Mage, Susanna M.; McHale, Patrick J.

    2011-06-01

    Despite the fact that atmospheric deposition is widely accepted to be an important process in the biogeochemical cycling of wooded ecosystems, no single study is known that has examined stemflow chemistry in relation to atmospheric deposition across time scales, from within discrete events to season, to chronicle alterations in temporal patterns of stemflow chemistry. This research partitioned stemflow solute fluxes (K +, Na +, Mg 2+, Ca 2+, Cl -, NO 3-, and SO 42-) from two tree species of differing canopy form and bark morphology into their leaching and dry deposition washoff components using a modified Kazda (1990) integration model at the intra-storm scale to examine differences within and among discrete rain events. Median annual stemflow concentrations in yellow poplar ( Liriodendron tulipifera L.) stemflow were higher than American beech ( Fagus grandifolia Ehrh.) stemflow for all ions except NO 3-. Beech median enrichment ratios were larger for all monitored ions than yellow poplar. All intra-storm stemflow ionic fluxes were initially high, exponentially decaying to a steady input, typically dominated by leaching contributions. With the exception of yellow poplar stemflow Cl - and NO 3- fluxes and beech Na + flux, all intra-storm mean ionic fluxes began with higher dry deposition percentages and transitioned to primarily leaching. Observations in the field implicate increased magnitude and rainfall intensity in the initiation of new stemflow flowpaths, evidenced by increased variability in the timing of stemflow ionic deposition and fluctuations in the proportion of washoff and leaching during some events. Beech stemflow fluxes were larger than yellow poplar for all ions during the leafed, leafless, and annual periods. Our results demonstrate: (1) the critical role of the initiation of new flowpaths and expansion and maturation of developed flowpaths on a tree's surface to solute enrichment and transport to the forest floor as a canopy wets-up; and (2) the

  10. Venusian atmospheric equilibrium chemistry at the Pioneer Venus anomalous event altitude

    NASA Technical Reports Server (NTRS)

    Craig, Roger A.

    1994-01-01

    No convincing explanation for the anomalous behavior of the Atmospheric Structure Experiment temperature sensors at approximately 13 km altitude has been found. It occurred on all of the widely-spaced probes, in a similar fashion. A preliminary effort has been made to determine atmospheric chemical species which might be present at 13 km. The purpose of this effort is to initiate suggestions of possible chemical interactions and to explore the effects of the presence of possible metal reactants including condensation. Equilibrium fractions of chemical species were calculated at a variety of conditions. Baseline calculations were made for the altitudes near 13 km. For comparison calculations were also made at 13 km but with the introduction of plausible metal atoms.

  11. Atmospheric chemistry. Direct kinetic measurement of the reaction of the simplest Criegee intermediate with water vapor.

    PubMed

    Chao, Wen; Hsieh, Jun-Ting; Chang, Chun-Hung; Lin, Jim Jr-Min

    2015-02-13

    Carbonyl oxides, or Criegee intermediates, are important transient species formed in the reactions of unsaturated hydrocarbons with ozone. Although direct detection of Criegee intermediates has recently been realized, the main atmospheric sink of Criegee intermediates remains unclear. We report ultraviolet absorption spectroscopic measurements of the lifetime of the simplest Criegee intermediate, CH2OO, at various relative humidity levels up to 85% at 298 kelvin. An extremely fast decay rate of CH2OO was observed at high humidity. The observed quadratic dependence of the decay rate on water concentration implied a predominant reaction with water dimer. On the basis of the water dimer equilibrium constant, the effective rate coefficient of the CH2OO + (H2O)2 reaction was determined to be 6.5 (±0.8) × 10(-12) cubic centimeters per second. This work would help modelers to better constrain the atmospheric concentrations of CH2OO. PMID:25569112

  12. Solar cosmic ray effects in atmospheric chemistry evidenced from ground-based measurements

    NASA Astrophysics Data System (ADS)

    Shumilov, O. I.; Kasatkina, E. A.; Turyansky, V. A.; Kyro, E.; Kivi, R.

    2003-05-01

    Ground-based measurements of nitrogen dioxide (N02) total content and photochemical modeling have been used to investigate the response of high-latitude atmosphere to solar proton events of Ground Level Event (GLE) type. Measurements of NO 2 were made at Murmansk, Kola Peninsula (corrected geomagnetic latitude: 64.8°) during and after GLE of 2 May 1998. Nitrogen dioxide was measured by zenith viewing spectrophotometer in wavelength range between 435 and 450 nm. An increase (about of 20%) in total column of N02 has been detected after 2 May 1998 GLE by this facility. Model calculations based on gas phase photochemical theory quantitatively agree with observations. These results demonstrate that information obtained from ground-based measurements is usable to study the atmospheric effects of high-energy solar protons in addition to satellite data.

  13. Carbon oxidation state as a metric for describing the chemistry of atmospheric organic aerosol

    SciTech Connect

    Massachusetts Institute of Technology; Kroll, Jesse H.; Donahue, Neil M.; Jimenez, Jose L.; Kessler, Sean H.; Canagaratna, Manjula R.; Wilson, Kevin R.; Altieri, Katye E.; Mazzoleni, Lynn R.; Wozniak, Andrew S.; Bluhm, Hendrik; Mysak, Erin R.; Smith, Jared D.; Kolb, Charles E.; Worsnop, Douglas R.

    2010-11-05

    A detailed understanding of the sources, transformations, and fates of organic species in the environment is crucial because of the central roles that organics play in human health, biogeochemical cycles, and Earth's climate. However, such an understanding is hindered by the immense chemical complexity of environmental mixtures of organics; for example, atmospheric organic aerosol consists of at least thousands of individual compounds, all of which likely evolve chemically over their atmospheric lifetimes. Here we demonstrate the utility of describing organic aerosol (and other complex organic mixtures) in terms of average carbon oxidation state (OSC), a quantity that always increases with oxidation, and is readily measured using state-of-the-art analytical techniques. Field and laboratory measurements of OSC , using several such techniques, constrain the chemical properties of the organics and demonstrate that the formation and evolution of organic aerosol involves simultaneous changes to both carbon oxidation state and carbon number (nC).

  14. Atmospheric chemistry of toxic contaminants 4. Saturated halogenated aliphatics: Methyl bromide, epichlorhydrin, phosgene

    SciTech Connect

    Grosjean, D. )

    1991-01-01

    Mechanisms are outlined for the reactions that contribute to in-situ formation and atmospheric removal of the saturated halogenated aliphatic contaminants methyl bromide, epichlorhydrin, and phosgene. In-situ formation is important only for phosgene and involves the reaction of OH with chloroethenes and other chlorinated hydrocarbons. A ranking of these phosgene precursors is given using data for precursor ambient concentrations and chemical reactivity. The three toxic compounds studied are long-lived in the atmosphere, where removal of phosgene and methyl bromide by chemical reactions is negligibly slow. Epichlorhydrin is removed slowly by reaction with OH, leading to formaldehyde, chloroacetaldehyde, and the chlorinated peroxyacyl nitrate CH{sub 2}ClC(O)OONO{sub 2}.

  15. Cosmogenic 35S: A unique tracer to Antarctic atmospheric chemistry and the polar vortex

    NASA Astrophysics Data System (ADS)

    Priyadarshi, Antra; Dominguez, Gerardo; Savarino, Joel; Thiemens, Mark

    2011-07-01

    The cosmogenic radionuclide 35S (half life ˜87 d) exists in both 35SO2 gas and 35SO42- aerosol phase in the atmosphere. Cosmogenic 35S fulfils a unique niche in that it has an ideal half-life for use as a tracer of atmospheric processes, possesses a gas phase precursor and undergoes gas to particle conversion, providing a chronometer that complements other measurements of radiogenic isotopes of different half lives and chemical properties. Based on radiogenic 35S measurements and concomitant model calculations, we demonstrate that 35S is a unique tracer to understand stratospheric-tropospheric air mass transport dynamics and the atmospheric oxidation capacity on a short time scale. Reported are the first measurements of 35S contained in SO42- aerosols (bulk and size aggregated) at Antarctica. 35SO42- concentrations at Dome C and Dumont D'Urville exhibit summer maxima and winter minima with a secondary winter peak. Higher oxidative capacity of the atmosphere and long range transport of mid latitude air increases 35SO42- activity in summer whereas a lack of air mass mixing coupled with low oxidant concentration in winter significantly decreases 35SO42- activity. A 3% contribution from stratospheric 35SO42- into the free troposphere during stratosphere-troposphere air mass mixing accounts for the secondary winter 35SO42- peak. In the future, this work will be extended to 35S activity measurements of both gas and aerosol phases to further understand gas to particle conversion, vortex dynamics and trace polar stratospheric cloud sedimentation frequency.

  16. Extrasolar Storms: The Physics and Chemistry of Evolving Cloud Structures in Brown Dwarf Atmospheres

    NASA Astrophysics Data System (ADS)

    Apai, Daniel

    2012-10-01

    Condensate clouds pose the most significant challenge to the understanding of ultracool atmospheres of brown dwarfs and giant exoplanets. In three ongoing Spitzer programs we have taken advantage of Spitzer's ability to obtain high-cadence uninterrupted observations to pioneer a new technique, rotational phase mapping, and successfully explored the properties of cloud covers in ~50 brown dwarfs. Among other exciting results we found that most brown dwarfs possess heterogeneous cloud cover, often with complex surface structures. Perhaps the most perplexing behavior seen in our surveys is light curve evolution on timescales as short as 5 hours and as long as a year. This unexpected behavior offers a unique opportunity to explore the dynamics of cloud layers, but requires multi-epoch data sets. We propose here to follow up a representative set of varying brown dwarfs via multi-epoch Spitzer and HST phase mapping to carry out the first quantitative exploration of cloud cover evolution. The proposed study will establish the first time-resolved multi-wavelength light curve library for brown dwarfs. Spitzer uniquely offers precise 3-5 micron photometry and continuous coverage that allow us to detect cloud structures a fraction of the size of the Great Red Spot on Jupiter in our targets. Combined with HST grism spectroscopy during a subset of the Spitzer observations, the Spitzer phase maps will allow us to disentangle the effects of cloud formation, differential rotation, large-scale rainout and dispersal of clouds. As different wavelengths probe different pressures and different rotational phases probe different latitudes we will be able to explore the two or even three-dimensional structure of the atmospheres. We will also constrain the dynamical and radiative timescales for brown dwarfs and compare these to theoretical predictions to identify the underlying atmospheric dynamics. This program will leave a unique legacy that will propel studies of ultracool atmosphere

  17. Extrasolar Storms: The Physics and Chemistry of Evolving Cloud Structures in Brown Dwarf Atmospheres

    NASA Astrophysics Data System (ADS)

    Apai, Daniel; Buenzli, Esther; Flateau, Davin; Metchev, Stanimir; Marley, Mark; Radigan, Jacqueline; Lowrance, Patrick; Showman, Adam; Artigau, Etienne; Heinze, Aren; Burgasser, Adam; Mohanty, Subhanjoy

    2012-09-01

    Condensate clouds pose the most significant challenge to the understanding of ultracool atmospheres of brown dwarfs and giant?exoplanets. In three ongoing Spitzer programs we have?taken advantage of Spitzer's ability to obtain high-cadence uninterrupted observations to pioneer a new technique, rotational phase mapping, and successfully explored the properties of cloud covers in ~50 brown?dwarfs. Among other exciting results we found that most brown dwarfs possess heterogeneous cloud cover, often with complex surface structures. Perhaps the most perplexing behavior seen in our surveys is light curve evolution on timescales as short as 5 hours and as long as a year. This unexpected behavior offers a unique opportunity to explore the dynamics of cloud layers, but requires multi-epoch data sets. We propose here to follow up a representative set of varying brown dwarfs via multi-epoch Spitzer and HST phase mapping to carry out the first quantitative exploration of cloud cover evolution. The proposed study will establish the first time-resolved multi-wavelength light curve library for brown dwarfs. Spitzer uniquely offers precise 3-5 micron photometry and continuous coverage that allow us to detect cloud structures a fraction of the size of the Great Red Spot on Jupiter in our targets. Combined with HST grism spectroscopy during a subset of the Spitzer observations, the Spitzer phase maps will allow us to disentangle the effects of cloud formation, differential rotation, large-scale rainout and dispersal of clouds. As different wavelengths probe different pressures and different rotational phases probe different latitudes we will be able to explore the two or even three-dimensional structure of the atmospheres. We will also constrain the dynamical and radiative timescales for brown dwarfs and compare these to theoretical predictions to identify the underlying atmospheric dynamics. This program will leave a unique legacy that will propel studies of ultracool atmosphere