Atmospheric Chemistry and Air Pollution

DOE PAGES

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

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...

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.

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.

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.

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.

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.

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.

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.

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.

Atmospheric chemistry: Description of the area of performance and a working plan

NASA Astrophysics Data System (ADS)

Kirchhoff, Volker W. J. H.

1986-11-01

INPE's program in Atmospheric Chemistry Research is described. Research in this area is concerned with atmospheric gases and their chemical reactions, production and loss rates, and their interactions with the biosphere. Atmospheric chemistry includes concepts in Physics, Chemistry, Meteorology, and Biology, which gives it a strong interdisciplinary character. The interaction of some of the atmospheric gases with the biosphere, such as ozone, is very strong and direct. Studying atmospheric chemistry is, therefore, of direct interest to man and the quality of life. Details are described to define the objectives of study, in particular those of our research program at INPE. A working plan is proposed in order to reach the defined goals. Owing to the large anthropogenic interference in the balance of the natural atmosphere it is anticipated that a better understanding of Atmospheric Chemistry will be the great scientific challenge of the next decade.

Collaborative Research: Atmospheric Pressure Microplasma Chemistry-Photon Synergies Final Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graves, David

Combining the effects of low temperature, atmospheric pressure microplasmas and microplasma photon sources shows greatly expanded range of applications of each of them. The plasma sources create active chemical species and these can be activated further by addition of photons and associated photochemistry. There are many ways to combine the effects of plasma chemistry and photochemistry, especially if there are multiple phases present. The project combines construction of appropriate test experimental systems, various spectroscopic diagnostics and mathematical modeling.

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.;

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lamarque, Jean-Francois; Dentener, Frank; McConnell, J.R.

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 Unitedmore » 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.« less

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.

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.

Exoplanetary Atmospheres-Chemistry, Formation Conditions, and Habitability.

PubMed

Madhusudhan, Nikku; Agúndez, Marcelino; Moses, Julianne I; Hu, Yongyun

2016-12-01

Characterizing the atmospheres of extrasolar planets is the new frontier in exoplanetary science. The last two decades of exoplanet discoveries have revealed that exoplanets are very common and extremely diverse in their orbital and bulk properties. We now enter a new era as we begin to investigate the chemical diversity of exoplanets, their atmospheric and interior processes, and their formation conditions. Recent developments in the field have led to unprecedented advancements in our understanding of atmospheric chemistry of exoplanets and the implications for their formation conditions. We review these developments in the present work. We review in detail the theory of atmospheric chemistry in all classes of exoplanets discovered to date, from highly irradiated gas giants, ice giants, and super-Earths, to directly imaged giant planets at large orbital separations. We then review the observational detections of chemical species in exoplanetary atmospheres of these various types using different methods, including transit spectroscopy, Doppler spectroscopy, and direct imaging. In addition to chemical detections, we discuss the advances in determining chemical abundances in these atmospheres and how such abundances are being used to constrain exoplanetary formation conditions and migration mechanisms. Finally, we review recent theoretical work on the atmospheres of habitable exoplanets, followed by a discussion of future outlook of the field.

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.;

Updated operational protocols for the U.S. Geological Survey Precipitation Chemistry Quality Assurance Project in support of the National Atmospheric Deposition Program

USGS Publications Warehouse

Wetherbee, Gregory A.; Martin, RoseAnn

2017-02-06

The U.S. Geological Survey Branch of Quality Systems operates the Precipitation Chemistry Quality Assurance Project (PCQA) for the National Atmospheric Deposition Program/National Trends Network (NADP/NTN) and National Atmospheric Deposition Program/Mercury Deposition Network (NADP/MDN). Since 1978, various programs have been implemented by the PCQA to estimate data variability and bias contributed by changing protocols, equipment, and sample submission schemes within NADP networks. These programs independently measure the field and laboratory components which contribute to the overall variability of NADP wet-deposition chemistry and precipitation depth measurements. The PCQA evaluates the quality of analyte-specific chemical analyses from the two, currently (2016) contracted NADP laboratories, Central Analytical Laboratory and Mercury Analytical Laboratory, by comparing laboratory performance among participating national and international laboratories. Sample contamination and stability are evaluated for NTN and MDN by using externally field-processed blank samples provided by the Branch of Quality Systems. A colocated sampler program evaluates the overall variability of NTN measurements and bias between dissimilar precipitation gages and sample collectors.This report documents historical PCQA operations and general procedures for each of the external quality-assurance programs from 2007 to 2016.

The Essential Role for Laboratory Studies in Atmospheric Chemistry.

PubMed

Burkholder, James B; Abbatt, Jonathan P D; Barnes, Ian; Roberts, James M; Melamed, Megan L; Ammann, Markus; Bertram, Allan K; Cappa, Christopher D; Carlton, Annmarie G; Carpenter, Lucy J; Crowley, John N; Dubowski, Yael; George, Christian; Heard, Dwayne E; Herrmann, Hartmut; Keutsch, Frank N; Kroll, Jesse H; McNeill, V Faye; Ng, Nga Lee; Nizkorodov, Sergey A; Orlando, John J; Percival, Carl J; Picquet-Varrault, Bénédicte; Rudich, Yinon; Seakins, Paul W; Surratt, Jason D; Tanimoto, Hiroshi; Thornton, Joel A; Tong, Zhu; Tyndall, Geoffrey S; Wahner, Andreas; Weschler, Charles J; Wilson, Kevin R; Ziemann, Paul J

2017-03-07

Laboratory studies of atmospheric chemistry characterize the nature of atmospherically relevant processes down to the molecular level, providing fundamental information used to assess how human activities drive environmental phenomena such as climate change, urban air pollution, ecosystem health, indoor air quality, and stratospheric ozone depletion. Laboratory studies have a central role in addressing the incomplete fundamental knowledge of atmospheric chemistry. This article highlights the evolving science needs for this community and emphasizes how our knowledge is far from complete, hindering our ability to predict the future state of our atmosphere and to respond to emerging global environmental change issues. Laboratory studies provide rich opportunities to expand our understanding of the atmosphere via collaborative research with the modeling and field measurement communities, and with neighboring disciplines.

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

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.

Chemistry and spectroscopy of the Jovian atmosphere

NASA Technical Reports Server (NTRS)

Prinn, R. G.; Owen, T.

1976-01-01

A comprehensive review is given of the chemistry and spectroscopic studies of the Jovian atmosphere. Thermochemical equilibrium models for determining atmospheric composition are considered along with possible disequilibrating processes, and studies of the photochemistry of H2, CH4, NH3, H2S, and PH3 using the modeling methods are summarized. It is shown that photodissociation and advection are the major disequilibrating processes in Jupiter's atmosphere, that lightning and charged-particle bombardment are relatively minor factors in the planet's bulk chemistry, and that the existence of living organisms on the planet is highly improbable. Spectroscopic investigations of Jupiter are discussed, emphasizing recent observations of absorption bands due to CH4, NH3, H2, He, and D. Spectroscopic abundance determinations are examined for H2, HD, CH4, CH3D, NH3, C2H6, C2H2, and PH3. Upper limits are given for the abundances of several unobserved gases in the visible atmosphere, including H2S, HCl, SiH4, benzene, purines, pyrimidines, and their derivatives.

The Essential Role for Laboratory Studies in Atmospheric Chemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burkholder, James B.; Abbatt, Jonathan P. D.; Barnes, Ian

Laboratory studies of atmospheric chemistry characterize the nature of atmospherically relevant processes down to the molecular level, providing fundamental information used to assess how human activities drive environmental phenomena such as climate change, urban air pollution, ecosystem health, indoor air quality, and stratospheric ozone depletion. Laboratory studies have a central role in addressing the incomplete fundamental knowledge of atmospheric chemistry. This paper highlights the evolving science needs for this community and emphasizes how our knowledge is far from complete, hindering our ability to predict the future state of our atmosphere and to respond to emerging global environmental change issues. Finally,more » laboratory studies provide rich opportunities to expand our understanding of the atmosphere via collaborative research with the modeling and field measurement communities, and with neighboring disciplines.« less

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...

Chemistry of the atmosphere: Its impact on global change

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 themore » 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.« less

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.

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.

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...

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.

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.

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

Variational methods for direct/inverse problems of atmospheric dynamics and chemistry

NASA Astrophysics Data System (ADS)

Penenko, Vladimir; Penenko, Alexey; Tsvetova, Elena

2013-04-01

monotone and stable discrete-analytical numerical schemes [1]-[3] conserving the positivity of the chemical substance concentrations and possessing the properties of energy and mass balance that are postulated in the general variational principle for integrated models. All algorithms for solution of transport, diffusion and transformation problems are direct (without iterations). The work is partially supported by the Programs No 4 of Presidium RAS and No 3 of Mathematical Department of RAS, by RFBR project 11-01-00187 and Integrating projects of SD RAS No 8 and 35. Our studies are in the line with the goals of COST Action ES1004. References Penenko V., Tsvetova E. Discrete-analytical methods for the implementation of variational principles in environmental applications// Journal of computational and applied mathematics, 2009, v. 226, 319-330. Penenko A.V. Discrete-analytic schemes for solving an inverse coefficient heat conduction problem in a layered medium with gradient methods// Numerical Analysis and Applications, 2012, V. 5, pp 326-341. V. Penenko, E. Tsvetova. Variational methods for constructing the monotone approximations for atmospheric chemistry models //Numerical Analysis and Applications, 2013 (in press).

Product Quality of ESA's Atmospheric-Chemistry Missions

NASA Astrophysics Data System (ADS)

Dehn, Angelika; Bojkov, Bojan; Fehr, Thorsten

2012-11-01

ESA's Atmospheric Chemistry Mission is providing fundamental information for the understanding of atmospheric chemistry processes. The global datasets are supporting climate research, air quality assessments, stratospheric ozone monitoring and many other science areas and operational services.ENVISAT with GOMOS, MIPAS and SCIAMACHY has contributed to a unique data set over a period of 10 years, before its major anomaly in April 2012, leading to the end of the operational part of the mission. GOME, on board ERS-2 has been acquiring data for 16 years, before it's de-commissioning in July 2011.The quality of the corresponding data sets is continuously being improved, also beyond the termination of the satellite's operational phases. This is realised with the support of numerous teams of science experts, evolving the algorithm and calibration baseline and validation teams assessing the resulting upgraded data sets.

Collaborative Research. Atmospheric Pressure Microplasma Chemistry-Photon Synergies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Sung-Jin; Eden, James Gary

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 completedmore » 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/cm 2 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.« less

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.

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…

Particle precipitation: How the spectrum fit impacts atmospheric chemistry

NASA Astrophysics Data System (ADS)

Wissing, J. M.; Nieder, H.; Yakovchouk, O. S.; Sinnhuber, M.

2016-11-01

Particle precipitation causes atmospheric ionization. Modeled ionization rates are widely used in atmospheric chemistry/climate simulations of the upper atmosphere. As ionization rates are based on particle measurements some assumptions concerning the energy spectrum are required. While detectors measure particles binned into certain energy ranges only, the calculation of a ionization profile needs a fit for the whole energy spectrum. Therefore the following assumptions are needed: (a) fit function (e.g. power-law or Maxwellian), (b) energy range, (c) amount of segments in the spectral fit, (d) fixed or variable positions of intersections between these segments. The aim of this paper is to quantify the impact of different assumptions on ionization rates as well as their consequences for atmospheric chemistry modeling. As the assumptions about the particle spectrum are independent from the ionization model itself the results of this paper are not restricted to a single ionization model, even though the Atmospheric Ionization Module OSnabrück (AIMOS, Wissing and Kallenrode, 2009) is used here. We include protons only as this allows us to trace changes in the chemistry model directly back to the different assumptions without the need to interpret superposed ionization profiles. However, since every particle species requires a particle spectrum fit with the mentioned assumptions the results are generally applicable to all precipitating particles. The reader may argue that the selection of assumptions of the particle fit is of minor interest, but we would like to emphasize on this topic as it is a major, if not the main, source of discrepancies between different ionization models (and reality). Depending on the assumptions single ionization profiles may vary by a factor of 5, long-term calculations may show systematic over- or underestimation in specific altitudes and even for ideal setups the definition of the energy-range involves an intrinsic 25% uncertainty for the

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.

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.

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.

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.

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.

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.

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.

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.

The effects of atmospheric chemistry on radiation budget in the Community Earth Systems Model

NASA Astrophysics Data System (ADS)

Choi, Y.; Czader, B.; Diao, L.; Rodriguez, J.; Jeong, G.

2013-12-01

The Community Earth Systems Model (CESM)-Whole Atmosphere Community Climate Model (WACCM) simulations were performed to study the impact of atmospheric chemistry on the radiation budget over the surface within a weather prediction time scale. The secondary goal is to get a simplified and optimized chemistry module for the short time period. Three different chemistry modules were utilized to represent tropospheric and stratospheric chemistry, which differ in how their reactions and species are represented: (1) simplified tropospheric and stratospheric chemistry (approximately 30 species), (2) simplified tropospheric chemistry and comprehensive stratospheric chemistry from the Model of Ozone and Related Chemical Tracers, version 3 (MOZART-3, approximately 60 species), and (3) comprehensive tropospheric and stratospheric chemistry (MOZART-4, approximately 120 species). Our results indicate the different details in chemistry treatment from these model components affect the surface temperature and impact the radiation budget.

An Overview of Atmospheric Chemistry and Air Quality Modeling

NASA Technical Reports Server (NTRS)

Johnson, Matthew S.

2017-01-01

This presentation will include my personal research experience and an overview of atmospheric chemistry and air quality modeling to the participants of the NASA Student Airborne Research Program (SARP 2017). The presentation will also provide examples on ways to apply airborne observations for chemical transport (CTM) and air quality (AQ) model evaluation. CTM and AQ models are important tools in understanding tropospheric-stratospheric composition, atmospheric chemistry processes, meteorology, and air quality. This presentation will focus on how NASA scientist currently apply CTM and AQ models to better understand these topics. Finally, the importance of airborne observation in evaluating these topics and how in situ and remote sensing observations can be used to evaluate and improve CTM and AQ model predictions will be highlighted.

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.

Organic chemistry in a CO2 rich early Earth atmosphere

NASA Astrophysics Data System (ADS)

Fleury, Benjamin; Carrasco, Nathalie; Millan, Maëva; Vettier, Ludovic; Szopa, Cyril

2017-12-01

The emergence of life on the Earth has required a prior organic chemistry leading to the formation of prebiotic molecules. The origin and the evolution of the organic matter on the early Earth is not yet firmly understood. Several hypothesis, possibly complementary, are considered. They can be divided in two categories: endogenous and exogenous sources. In this work we investigate the contribution of a specific endogenous source: the organic chemistry occurring in the ionosphere of the early Earth where the significant VUV contribution of the young Sun involved an efficient formation of reactive species. We address the issue whether this chemistry can lead to the formation of complex organic compounds with CO2 as only source of carbon in an early atmosphere made of N2, CO2 and H2, by mimicking experimentally this type of chemistry using a low pressure plasma reactor. By analyzing the gaseous phase composition, we strictly identified the formation of H2O, NH3, N2O and C2N2. The formation of a solid organic phase is also observed, confirming the possibility to trigger organic chemistry in the upper atmosphere of the early Earth. The identification of Nitrogen-bearing chemical functions in the solid highlights the possibility for an efficient ionospheric chemistry to provide prebiotic material on the early Earth.

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

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

Do airborne microbes matter for atmospheric chemistry and cloud formation?

PubMed

Konstantinidis, Konstantinos T

2014-06-01

The role of airborne microbial cells in the chemistry of the atmosphere and cloud formation remains essentially speculative. Recent studies have indicated that microbes might be more important than previously anticipated for atmospheric processes. However, more work and direct communication between microbiologists and atmospheric scientists and modellers are necessary to better understand and model bioaerosol-cloud-precipitation-climate interactions. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

Aerosols in atmospheric chemistry and biogeochemical cycles of nutrients

NASA Astrophysics Data System (ADS)

Kanakidou, Maria; Myriokefalitakis, Stelios; Tsigaridis, Kostas

2018-06-01

Atmospheric aerosols have complex and variable compositions and properties. While scientific interest is centered on the health and climatic effects of atmospheric aerosols, insufficient attention is given to their involvement in multiphase chemistry that alters their contribution as carriers of nutrients in ecosystems. However, there is experimental proof that the nutrient equilibria of both land and marine ecosystems have been disturbed during the Anthropocene period. This review study first summarizes our current understanding of aerosol chemical processing in the atmosphere as relevant to biogeochemical cycles. Then it binds together results of recent modeling studies based on laboratory and field experiments, focusing on the organic and dust components of aerosols that account for multiphase chemistry, aerosol ageing in the atmosphere, nutrient (N, P, Fe) emissions, atmospheric transport, transformation and deposition. The human-driven contribution to atmospheric deposition of these nutrients, derived by global simulations using past and future anthropogenic emissions of pollutants, is put into perspective with regard to potential changes in nutrient limitations and biodiversity. Atmospheric deposition of nutrients has been suggested to result in human-induced ecosystem limitations with regard to specific nutrients. Such modifications favor the development of certain species against others and affect the overall functioning of ecosystems. Organic forms of nutrients are found to contribute to the atmospheric deposition of the nutrients N, P and Fe by 20%–40%, 35%–45% and 7%–18%, respectively. These have the potential to be key components of the biogeochemical cycles since there is initial proof of their bioavailability to ecosystems. Bioaerosols have been found to make a significant contribution to atmospheric sources of N and P, indicating potentially significant interactions between terrestrial and marine ecosystems. These results deserve further

Validation of the ENVISAT atmospheric chemistry instruments

NASA Astrophysics Data System (ADS)

Snoeij, P.; Koopman, R.; Attema, E.; Zehner, C.; Wursteisen, P.; Dehn, A.; de Laurentius, M.; Frerick, J.; Mantovani, R.; Saavedra de Miguel, L.

Three atmospheric-chemistry sensors form part of the ENVISAT payload that has been placed into orbit in March 2002. This paper presents the ENVISAT mission status and data policy, and reviews the end-to-end performance of the GOMOS, MIPAS and SCIAMACHY observation systems and will discuss the validation aspects of these instruments. In particular, for each instrument, the review addresses mission planning, in-orbit performance, calibration, data processor algorithms and configuration, reprocessing strategy, and product quality control assessment. An important part of the quality assessment is the Geophysical Validation. At the ACVT Validation workshop held in Frascati, Italy, from 3-7 May 2004, scientists and engineers presented analyses of the exhaustive series of tests that have been run on each of ENVISAT atmospheric chemistry sensors since the spacecraft was launched in March 2002. On the basis of workshop results it was decided that most of the data products provided by the ENVISAT atmospheric chemistry instruments are ready for operational delivery. Although the main validation phase for the atmospheric instruments of ENVISAT will be completed soon, ongoing validation products will continue throughout the lifetime of the ENVISAT mission. The long-term validation phase will: Provide assurance of data quality and accuracy for applications such as climate change research Investigate the fully representative range of geophysical conditions Investigate the fully representative range of seasonal cycles Perform long term monitoring for instrumental drifts and other artefacts Validate new products. This paper will also discuss the general status of the validation activities for GOMOS, MIPAS and SCIAMACHY. The main and long-term geophysical validation programme will be presented. The flight and ground-segment planning, configuration and performance characterization will be discussed. The evolution of each of the observation systems has been distinct during the mission

Machine learning of atmospheric chemistry. Applications to a global chemistry transport model.

NASA Astrophysics Data System (ADS)

Evans, M. J.; Keller, C. A.

2017-12-01

Atmospheric chemistry is central to many environmental issues such as air pollution, climate change, and stratospheric ozone loss. Chemistry Transport Models (CTM) are a central tool for understanding these issues, whether for research or for forecasting. These models split the atmosphere in a large number of grid-boxes and consider the emission of compounds into these boxes and their subsequent transport, deposition, and chemical processing. The chemistry is represented through a series of simultaneous ordinary differential equations, one for each compound. Given the difference in life-times between the chemical compounds (mili-seconds for O(1D) to years for CH4) these equations are numerically stiff and solving them consists of a significant fraction of the computational burden of a CTM.We have investigated a machine learning approach to solving the differential equations instead of solving them numerically. From an annual simulation of the GEOS-Chem model we have produced a training dataset consisting of the concentration of compounds before and after the differential equations are solved, together with some key physical parameters for every grid-box and time-step. From this dataset we have trained a machine learning algorithm (random regression forest) to be able to predict the concentration of the compounds after the integration step based on the concentrations and physical state at the beginning of the time step. We have then included this algorithm back into the GEOS-Chem model, bypassing the need to integrate the chemistry.This machine learning approach shows many of the characteristics of the full simulation and has the potential to be substantially faster. There are a wide range of application for such an approach - generating boundary conditions, for use in air quality forecasts, chemical data assimilation systems, centennial scale climate simulations etc. We discuss our approches' speed and accuracy, and highlight some potential future directions for

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,…

Diagnosis of middle atmosphere chemistry-dynamics interactions

NASA Astrophysics Data System (ADS)

Zhu, X.; Swartz, W. H.; Garcia, R. R.; Chartier, A.; Yee, J. H.; Yue, J.

2017-12-01

We apply the recently developed middle atmosphere climate feedback-response analysis method (MCFRAM) to diagnosing the temperature variations associated with chemistry-dynamics interactions in the middle atmosphere. By using output fields from the Whole Atmosphere Community Climate Model (WACCM) coupled with the measurements, we identify and isolate the distinctive characteristics of different components in the observed temperature variations. Both the temperature trends associated with the anthropogenic forcing and temperature changes associated with natural and internal feedback processes are quantified based on MCFRAM defined partial temperature changes corresponding to localized radiative heating, non-localized chemical heating, eddy transport, and transport by the mean meridional circulation of energy and chemical species. In addition, the temperature responses to variations of CO2, O3, and solar flux have distinctly different spatial structures that can be systematically categorized by the eigenmodes of the generalized damping matrix derived from MCFRAM.

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.

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…

Nighttime atmospheric chemistry of iodine

NASA Astrophysics Data System (ADS)

Saiz-Lopez, Alfonso; Plane, John M. C.; Cuevas, Carlos A.; Mahajan, Anoop S.; Lamarque, Jean-François; Kinnison, Douglas E.

2016-12-01

Little attention has so far been paid to the nighttime atmospheric chemistry of iodine species. Current atmospheric models predict a buildup of HOI and I2 during the night that leads to a spike of IO at sunrise, which is not observed by measurements. In this work, electronic structure calculations are used to survey possible reactions that HOI and I2 could undergo at night in the lower troposphere, and hence reduce their nighttime accumulation. The new reaction NO3+ HOI → IO + HNO3 is proposed, with a rate coefficient calculated from statistical rate theory over the temperature range 260-300 K and at a pressure of 1000 hPa to be k(T) = 2.7 × 10-12 (300 K/T)2.66 cm3 molecule-1 s-1. This reaction is included in two atmospheric models, along with the known reaction between I2 and NO3, to explore a new nocturnal iodine radical activation mechanism. The results show that this iodine scheme leads to a considerable reduction of nighttime HOI and I2, which results in the enhancement of more than 25 % of nighttime ocean emissions of HOI + I2 and the removal of the anomalous spike of IO at sunrise. We suggest that active nighttime iodine can also have a considerable, so far unrecognized, impact on the reduction of the NO3 radical levels in the marine boundary layer (MBL) and hence upon the nocturnal oxidizing capacity of the marine atmosphere. The effect of this is exemplified by the indirect effect on dimethyl sulfide (DMS) oxidation.

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.

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

Reconciling Scientific Curiosity and Policy Needs in Atmospheric Chemistry Research

NASA Astrophysics Data System (ADS)

Jacob, D. J.

2002-05-01

Young people generally choose a career in atmospheric chemistry because they care about the environment and want to make a difference. However, in the course of graduate training this initial motivation often becomes replaced by the more standard motivation of academic scientists: to understand the world (and get credit for it). We are taught during our Ph.D. that the more fundamental the research the better to earn the respect of our peers. And yet, in environmental research where funding is dominated by societal and policy demands, most of us have no choice but to follow this funding trail. This is not simple venality. Fortunately, most atmospheric chemists want to be societally relevant, we thrive on the spotlight thrown by society on atmospheric chemistry issues, and we are thankful that societal concerns are allowing our science to grow at a fast pace. It appears that the atmospheric chemistry community resolves its conflict between policy-driven vs. fundamental research by posting policy relevance as the canon for successful research, as the endpoint of useful work. The greatest glory then comes from picking up some fundamental knowledge along the way that provides bridges to other problems, and from uncovering new environmental problems that will require attention from policymakers. Sometimes we are frustrated, as when policymakers decide that research on our favorite problem is not needed anymore because there is now policy to address it. But of course we have to remember what got our research funded in the first place, lobby as we can, and move on. I will present, rather pretentiously, a few examples from my own research.

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.

The coupled atmosphere-chemistry-ocean model SOCOL-MPIOM

NASA Astrophysics Data System (ADS)

Muthers, S.; Anet, J. G.; Stenke, A.; Raible, C. C.; Rozanov, E.; Brönnimann, S.; Peter, T.; Arfeuille, F. X.; Shapiro, A. I.; Beer, J.; Steinhilber, F.; Brugnara, Y.; Schmutz, W.

2014-05-01

The newly developed atmosphere-ocean-chemistry-climate model SOCOL-MPIOM is presented by demonstrating the influence of the interactive chemistry module on the climate state and the variability. Therefore, we compare pre-industrial control simulations with (CHEM) and without (NOCHEM) interactive chemistry. In general, the influence of the chemistry on the mean state and the variability is small and mainly restricted to the stratosphere and mesosphere. The largest differences are found for the atmospheric dynamics in the polar regions, with slightly stronger northern and southern winter polar vortices in CHEM. The strengthening of the vortex is related to larger stratospheric temperature gradients, which are attributed to a parametrization of the absorption of ozone and oxygen in the Lyman-alpha, Schumann-Runge, Hartley, and Higgins bands. This effect is parametrized in the version with interactive chemistry only. A second reason for the temperature differences between CHEM and NOCHEM is related to diurnal variations in the ozone concentrations in the higher atmosphere, which are missing in NOCHEM. Furthermore, stratospheric water vapour concentrations differ substantially between the two experiments, but their effect on the temperatures is small. In both setups, the simulated intensity and variability of the northern polar vortex is inside the range of present day observations. Sudden stratospheric warming events are well reproduced in terms of their frequency, but the distribution amongst the winter months is too uniform. Additionally, the performance of SOCOL-MPIOM under changing external forcings is assessed for the period 1600-2000 using an ensemble of simulations driven by a spectral solar forcing reconstruction. The amplitude of the reconstruction is large in comparison to other state-of-the-art reconstructions, providing an upper limit for the importance of the solar signal. In the pre-industrial period (1600-1850) the simulated surface temperature trends

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.

Nighttime atmospheric chemistry of iodine

DOE PAGES

Saiz-Lopez, Alfonso; Plane, John M. C.; Cuevas, Carlos A.; ...

2016-12-19

Little attention has so far been paid to the nighttime atmospheric chemistry of iodine species. Current atmospheric models predict a buildup of HOI and I 2 during the night that leads to a spike of IO at sunrise, which is not observed by measurements. In this work, electronic structure calculations are used to survey possible reactions that HOI and I 2 could undergo at night in the lower troposphere, and hence reduce their nighttime accumulation. The new reaction NO 3+ HOI → IO + HNO 3 is proposed, with a rate coefficient calculated from statistical rate theory over the temperaturemore » range 260–300 K and at a pressure of 1000 hPa to be k( T) = 2.7 × 10 -12 (300 K/ T) 2.66 cm 3 molecule -1 s -1. This reaction is included in two atmospheric models, along with the known reaction between I 2 and NO 3, to explore a new nocturnal iodine radical activation mechanism. The results show that this iodine scheme leads to a considerable reduction of nighttime HOI and I 2, which results in the enhancement of more than 25 % of nighttime ocean emissions of HOI + I 2 and the removal of the anomalous spike of IO at sunrise. We suggest that active nighttime iodine can also have a considerable, so far unrecognized, impact on the reduction of the NO 3 radical levels in the marine boundary layer (MBL) and hence upon the nocturnal oxidizing capacity of the marine atmosphere. In conclusion, the effect of this is exemplified by the indirect effect on dimethyl sulfide (DMS) oxidation.« less

Nighttime atmospheric chemistry of iodine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saiz-Lopez, Alfonso; Plane, John M. C.; Cuevas, Carlos A.

Little attention has so far been paid to the nighttime atmospheric chemistry of iodine species. Current atmospheric models predict a buildup of HOI and I 2 during the night that leads to a spike of IO at sunrise, which is not observed by measurements. In this work, electronic structure calculations are used to survey possible reactions that HOI and I 2 could undergo at night in the lower troposphere, and hence reduce their nighttime accumulation. The new reaction NO 3+ HOI → IO + HNO 3 is proposed, with a rate coefficient calculated from statistical rate theory over the temperaturemore » range 260–300 K and at a pressure of 1000 hPa to be k( T) = 2.7 × 10 -12 (300 K/ T) 2.66 cm 3 molecule -1 s -1. This reaction is included in two atmospheric models, along with the known reaction between I 2 and NO 3, to explore a new nocturnal iodine radical activation mechanism. The results show that this iodine scheme leads to a considerable reduction of nighttime HOI and I 2, which results in the enhancement of more than 25 % of nighttime ocean emissions of HOI + I 2 and the removal of the anomalous spike of IO at sunrise. We suggest that active nighttime iodine can also have a considerable, so far unrecognized, impact on the reduction of the NO 3 radical levels in the marine boundary layer (MBL) and hence upon the nocturnal oxidizing capacity of the marine atmosphere. In conclusion, the effect of this is exemplified by the indirect effect on dimethyl sulfide (DMS) oxidation.« less

Systematic evaluation of atmospheric chemistry-transport model CHIMERE

NASA Astrophysics Data System (ADS)

Khvorostyanov, Dmitry; Menut, Laurent; Mailler, Sylvain; Siour, Guillaume; Couvidat, Florian; Bessagnet, Bertrand; Turquety, Solene

2017-04-01

Regional-scale atmospheric chemistry-transport models (CTM) are used to develop air quality regulatory measures, to support environmentally sensitive decisions in the industry, and to address variety of scientific questions involving the atmospheric composition. Model performance evaluation with measurement data is critical to understand their limits and the degree of confidence in model results. CHIMERE CTM (http://www.lmd.polytechnique.fr/chimere/) is a French national tool for operational forecast and decision support and is widely used in the international research community in various areas of atmospheric chemistry and physics, climate, and environment (http://www.lmd.polytechnique.fr/chimere/CW-articles.php). This work presents the model evaluation framework applied systematically to the new CHIMERE CTM versions in the course of the continuous model development. The framework uses three of the four CTM evaluation types identified by the Environmental Protection Agency (EPA) and the American Meteorological Society (AMS): operational, diagnostic, and dynamic. It allows to compare the overall model performance in subsequent model versions (operational evaluation), identify specific processes and/or model inputs that could be improved (diagnostic evaluation), and test the model sensitivity to the changes in air quality, such as emission reductions and meteorological events (dynamic evaluation). The observation datasets currently used for the evaluation are: EMEP (surface concentrations), AERONET (optical depths), and WOUDC (ozone sounding profiles). The framework is implemented as an automated processing chain and allows interactive exploration of the results via a web interface.

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.

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).

Chemistry of the surface and lower atmosphere of Venus

NASA Technical Reports Server (NTRS)

Fegley, B., Jr.; Treiman, A.

1992-01-01

A comprehensive overview of the chemical interactions between the atmosphere and surface of Venus is presented. Earth-based, earth-orbital, and spacecraft data on the composition of the atmosphere and surface of Venus are presented and applied to quantitative evaluations of the chemical interactions between carbon, hydrogen, sulfur, chlorine, fluorine, and nitrogen-containing gases and possible minerals on the Venus surface. The calculation results are used to predict stable minerals and mineral assemblages on the Venus surface to determine which, if any, atmospheric gases are buffered by mineral assemblages on the surface, and to critically review and assess prior work on atmosphere-surface chemistry on Venus. It is concluded that the CO2 pressure on Venus is comparable to the CO2 equilibrium partial pressure developed by the calcite + wollastonite + quartz assemblage at the mean Venus surface temperature of 740 K.

The THS Experiment: Simulating Titans Atmospheric Chemistry at Low Temperature (200K)

NASA Technical Reports Server (NTRS)

Sciamma-O'Brien, Ella; Upton, Kathleen; Beauchamp, Jack L.; Salama, Farid; Contreras, Cesar Sanchez; Bejaoui, Salma; Foing, Bernard; Pascale, Ehrenfreund

2015-01-01

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 ( approximately 150K) before inducing the chemistry by plasma, and remains at low temperature in the plasma discharge (approximately 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[1] 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 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

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.

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.

"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.

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

Soil Moisture-Atmosphere Feedbacks on Atmospheric Tracers: The Effects of Soil Moisture on Precipitation and Near-Surface Chemistry

NASA Astrophysics Data System (ADS)

Tawfik, Ahmed B.

The atmospheric component is described by rapid fluctuations in typical state variables, such as temperature and water vapor, on timescales of hours to days and the land component evolves on daily to yearly timescales. This dissertation examines the connection between soil moisture and atmospheric tracers under varying degrees of soil moisture-atmosphere coupling. Land-atmosphere coupling is defined over the United States using a regional climate model. A newly examined soil moisture-precipitation feedback is identified for winter months extending the previous summer feedback to colder temperature climates. This feedback is driven by the freezing and thawing of soil moisture, leading to coupled land-atmosphere conditions near the freezing line. Soil moisture can also affect the composition of the troposphere through modifying biogenic emissions of isoprene (C5H8). A novel first-order Taylor series decomposition indicates that isoprene emissions are jointly driven by temperature and soil moisture in models. These compounds are important precursors for ozone formation, an air pollutant and a short-lived forcing agent for climate. A mechanistic description of commonly observed relationships between ground-level ozone and meteorology is presented using the concept of soil moisture-temperature coupling regimes. The extent of surface drying was found to be a better predictor of ozone concentrations than temperature or humidity for the Eastern U.S. This relationship is evaluated in a coupled regional chemistry-climate model under several land-atmosphere coupling and isoprene emissions cases. The coupled chemistry-climate model can reproduce the observed soil moisture-temperature coupling pattern, yet modeled ozone is insensitive to changes in meteorology due to the balance between isoprene and the primary atmospheric oxidant, the hydroxyl radical (OH). Overall, this work highlights the importance of soil moisture-atmosphere coupling for previously neglected cold climate

Photochemical Formation of Aerosol in Planetary Atmospheres: Photon and Water Mediated Chemistry of SO_2

NASA Astrophysics Data System (ADS)

Kroll, Jay A.; Donaldson, D. J.; Vaida, Veronica

2016-06-01

Sulfur compounds have been observed in a number of planetary atmospheres throughout our solar system. Our current understanding of sulfur chemistry explains much of what we observe in Earth's atmosphere. However, several discrepancies between modeling and observations of the Venusian atmosphere show there are still problems in our fundamental understanding of sulfur chemistry. This is of particular concern due to the important role sulfur compounds play in the formation of aerosols, which have a direct impact on planetary climates, including Earth's. We investigate the role of water complexes in the hydration of sulfur oxides and dehydration of sulfur acids and will present spectroscopic studies to document such effects. I will present recent work investigating mixtures of SO_2 and water that generate large quantities of aerosol when irradiated with solar UV light, even in the absence of traditional OH chemistry. I will discuss a proposed mechanism for the formation of sulfurous acid (H_2SO_3) and present recent experimental work that supports this proposed mechanism. Additionally, the implications that photon-induced hydration of SO_2 has for aerosol formation in the atmosphere of earth as well as other planetary atmospheres will be discussed.

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

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

Using high-frequency sampling to detect effects of atmospheric pollutants on stream chemistry

Treesearch

Stephen D. Sebestyen; James B. Shanley; Elizabeth W. Boyer

2009-01-01

We combined information from long-term (weekly over many years) and short-term (high-frequency during rainfall and snowmelt events) stream water sampling efforts to understand how atmospheric deposition affects stream chemistry. Water samples were collected at the Sleepers River Research Watershed, VT, a temperate upland forest site that receives elevated atmospheric...

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

Computer Series, 101: Accurate Equations of State in Computational Chemistry Projects.

ERIC Educational Resources Information Center

Albee, David; Jones, Edward

1989-01-01

Discusses the use of computers in chemistry courses at the United States Military Academy. Provides two examples of computer projects: (1) equations of state, and (2) solving for molar volume. Presents BASIC and PASCAL listings for the second project. Lists 10 applications for physical chemistry. (MVL)

Central role of carbonyl compounds in atmospheric chemistry

NASA Astrophysics Data System (ADS)

Lary, D. J.; Shallcross, D. E.

2000-08-01

With the exception of acetone it is not generally recognized how important atmospheric carbonyls and alkyl radicals are in the lower stratosphere and upper troposphere. Carbonyl compounds are the crucial intermediate species for the autocatalytic production of OH. For example, in the upper troposphere and lower stratosphere it is calculated based on data assimilation analysis of Atmospheric Trace Molecule Spectroscopy Experiment (ATMOS) data that CH3 production due to the degradation of carbonyls contributes around 40% to the overall production of CH3, a key initiation step for HOx production, with the contribution due to the photolysis of CH3CHO being comparable to that of acetone. So correctly modeling the alkyl radical concentrations is of central importance and has not be given the attention it deserves to date. The reactions of carbonyls with Br and Cl are also major sources of HBr and HCl. In short, carbonyl compounds play a central role in atmospheric chemistry close to the tropopause, and this is directly relevant to issues such as the assessment of the impact of air traffic, and ozone depletion.

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"); (c) the emerging instrumentation revolution and some of the challenges that it brings; (d) the structural issues of insufficient support for the analysis of field campaigns; and (e) some important areas that were missing from this Faraday Discussion and that should receive an increasing focus in the future.

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.

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…

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.

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

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

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.;

2011 Arctic ozone depletion as seen by ESA-ENVISAT Atmospheric-Chemistry sensors

NASA Astrophysics Data System (ADS)

Brizzi, G.; Niro, F.; Saavedra de Miguel, L.; Dehn, A.; Scarpino, G.; Fehr, T.; von Kuhlmann, R.

2011-12-01

Three Atmospheric-Chemistry sensors on-board the ENVISAT satellite (GOMOS, MIPAS, and SCIAMACHY) sound the Earth's atmosphere since about nine years and provide to the science community three separated, but complementary data sets of the most interesting atmospheric trace gases. These extended and coherent data sets, generated with ESA operational processors, give a historical overview over seasonal and long-term trends of geophysical parameters and allow investigating major atmospheric phenomena and natural events. During March 2011, ESA's satellite ENVISAT detected the severe ozone depletion above the Euro-Atlantic sector of the Northern Hemisphere. This record-breaking loss for the ozone layer over the North Pole was mainly caused by unusual polar vortex conditions characterized by very low temperatures in the Arctic stratosphere. This paper presents the chemical ozone depletion over the Arctic regions as detected by SCIAMACHY, MIPAS and GOMOS during spring of 2011. Global maps of total ozone column and vertical ozone profiles along the mission's lifetime clearly show the unprecedented Arctic ozone loss for 2011 with the subsequent migration of ozone depleted air masses towards lower latitudes. ENVISAT's atmospheric measurements reveal changes in the composition of the ozone-related chemical species and permit to point out the chemical correlations of the ozone distribution with nitrogen and chlorine compounds and with the evolution of stratospheric temperatures. The synergistic use of ESA operational data sets from the three instruments allows to closely monitor the occurrence and extension of seasonal ozone depletion events, and to draw a comprehensive picture of all chemistry processes involved in the full atmospheric range.

Middle Atmosphere Program. Handbook for MAP, volume 11

NASA Technical Reports Server (NTRS)

Sechrist, C. F., Jr. (Editor)

1984-01-01

An overview is presented of the research activities and objectives of the middle atmosphere program (MAP). Status reports are presented of projects underway in the area of middle atmosphere climatology and atmospheric chemistry condensed minutes of MAP steering committee meetings are contained in this volume. Research recommendations for increased U.S. participation in the middle atmosphere program are given.

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

Chemistry of Atmospheric Aerosols at Pacifichem 2015 Congress

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nizkorodov, Sergey

This grant was used to provide participant support for a symposium entitled “Chemistry of Atmospheric Aerosols” at the 2015 International Chemical Congress of Pacific Basin Societies (Pacifichem) that took place in Honolulu, Hawaii, USA, on December 15-20, 2015. The objective was to help attract both distinguished scientists as well as more junior researchers, including graduate students, to this international symposium by reducing the financial barrier for its attendance. It was the second time a symposium devoted to Atmospheric Aerosols was part of the Pacifichem program. This symposium provided a unique opportunity for the scientists from different countries to gather inmore » one place and discuss the cutting edge advances in the cross-disciplinary areas of aerosol research. To achieve the highest possible impact, the PI and the symposium co-organizers actively advertised the symposium by e-mail and by announcements at other conferences. A number of people responded, and the end result was a very busy program with about 100 oral and poster presentation described in the attached PDF file. Presentations by invited speakers occupied approximately 30% of time in each of the sessions. In addition to the invited speakers, each session also had contributed presentations, including those by graduate students and postdoctoral researchers. This symposium gathered established aerosol chemists from a number of countries including United States, Canada, China, Japan, Korea, Australia, Brazil, Hongkong, Switzerland, France, and Germany. There were plenty of time for the attendees to discuss new ideas and potential collaborations both during the oral sessions and at the poster sessions of the symposium. The symposium was very beneficial to graduate student researchers, postdoctoral fellows, and junior researchers whose prior exposure to international aerosol chemistry science had been limited. The symposium provided junior researchers with a much broader perspective of

"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…

From biota to chemistry and climate: towards a comprehensive description of trace gas exchange between the biosphere and atmosphere

NASA Astrophysics Data System (ADS)

Arneth, A.; Sitch, S.; Bondeau, A.; Butterbach-Bahl, K.; Foster, P.; Gedney, N.; de Noblet-Ducoudré, N.; Prentice, I. C.; Sanderson, M.; Thonicke, K.; Wania, R.; Zaehle, S.

2010-01-01

Exchange of non-CO2 trace gases between the land surface and the atmosphere plays an important role in atmospheric chemistry and climate. Recent studies have highlighted its importance for interpretation of glacial-interglacial ice-core records, the simulation of the pre-industrial and present atmosphere, and the potential for large climate-chemistry and climate-aerosol feedbacks in the coming century. However, spatial and temporal variations in trace gas emissions and the magnitude of future feedbacks are a major source of uncertainty in atmospheric chemistry, air quality and climate science. To reduce such uncertainties Dynamic Global Vegetation Models (DGVMs) are currently being expanded to mechanistically represent processes relevant to non-CO2 trace gas exchange between land biota and the atmosphere. In this paper we present a review of important non-CO2 trace gas emissions, the state-of-the-art in DGVM modelling of processes regulating these emissions, identify key uncertainties for global scale model applications, and discuss a methodology for model integration and evaluation.

From biota to chemistry and climate: towards a comprehensive description of trace gas exchange between the biosphere and atmosphere

NASA Astrophysics Data System (ADS)

Arneth, A.; Sitch, S.; Bondeau, A.; Butterbach-Bahl, K.; Foster, P.; Gedney, N.; de Noblet-Ducoudré, N.; Prentice, I. C.; Sanderson, M.; Thonicke, K.; Wania, R.; Zaehle, S.

2009-07-01

Exchange of non-CO2 trace gases between the land surface and the atmosphere plays an important role in atmospheric chemistry and climate. Recent studies have highlighted its importance for interpretation of glacial-interglacial ice-core records, the simulation of the pre-industrial and present atmosphere, and the potential for large climate-chemistry and climate-aerosol feedbacks in the coming century. However, spatial and temporal variations in trace gas emissions and the magnitude of future feedbacks are a major source of uncertainty in atmospheric chemistry, air quality and climate science. To reduce such uncertainties Dynamic Global Vegetation Models (DGVMs) are currently being expanded to mechanistically represent processes relevant to non-CO2 trace gas exchange between land biota and the atmosphere. In this paper we present a review of important non-CO2 trace gas emissions, the state-of-the-art in DGVM modelling of processes regulating these emissions, identify key uncertainties for global scale model applications, and discuss a methodology for model integration and evaluation.

Atmospheric Research 2016 Technical Highlights

NASA Technical Reports Server (NTRS)

Platnick, Steven

2017-01-01

Atmospheric research in the Earth Sciences Division (610) consists of research and technology development programs dedicated to advancing knowledge and understanding of the atmosphere and its interaction with the climate of Earth. The Divisions goals are to improve understanding of the dynamics and physical properties of precipitation, clouds, and aerosols; atmospheric chemistry, including the role of natural and anthropogenic trace species on the ozone balance in the stratosphere and the troposphere; and radiative properties of Earth's atmosphere and the influence of solar variability on the Earth's climate. Major research activities are carried out in the Mesoscale Atmospheric Processes Laboratory, the Climate and Radiation Laboratory, the Atmospheric Chemistry and Dynamics Laboratory, and the Wallops Field Support Office. The overall scope of the research covers an end-to-end process, starting with the identification of scientific problems, leading to observation requirements for remote-sensing platforms, technology and retrieval algorithm development; followed by flight projects and satellite missions; and eventually, resulting in data processing, analyses of measurements, and dissemination from flight projects and missions. Instrument scientists conceive, design, develop, and implement ultraviolet, infrared, optical, radar, laser, and lidar technology to remotely sense the atmosphere. Members of the various laboratories conduct field measurements for satellite sensor calibration and data validation, and carry out numerous modeling activities. These modeling activities include climate model simulations, modeling the chemistry and transport of trace species on regional-to-global scales, cloud resolving models, and developing the next-generation Earth system models. Satellite missions, field campaigns, peer-reviewed publications, and successful proposals are essential at every stage of the research process to meeting our goals and maintaining leadership of the

Laboratory Investigations of Stratospheric Halogen Chemistry

NASA Technical Reports Server (NTRS)

Wine, Paul H.; Nicovich, J. Michael; Stickel, Robert E.; Hynes, Anthony J.

1997-01-01

A final report for the NASA-supported project on laboratory investigations of stratospheric halogen chemistry is presented. In recent years, this project has focused on three areas of research: (1) kinetic, mechanistic, and thermochemical studies of reactions which produce weakly bound chemical species of atmospheric interest; (2) development of flash photolysis schemes for studying radical-radical reactions of stratospheric interest; and (3) photochemistry studies of interest for understanding stratospheric chemistry. The first section of this paper contains a discussion of work which has not yet been published. All subsequent chapters contain reprints of published papers that acknowledge support from this grant.

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.

Atmospheric Photooxidation Products and Chemistry of Current-use Pesticides

NASA Astrophysics Data System (ADS)

Murschell, T.; Farmer, D.

2017-12-01

Pesticides are widely used in agricultural, commercial, and residential applications across the United States. Pesticides can volatilize off targets and travel long distances, with atmospheric lifetimes determined by both physical and chemical loss processes. In particular, oxidation by the hydroxyl radical (OH) can reduce the lifetime and thus atmospheric transport of pesticides, though the rates and oxidation products of atmospheric pesticide oxidation are poorly understood. Here, we investigate reactions of current-use pesticides with OH. MCPA, triclopyr, and fluroxypyr are herbicides that are often formulated together to target broadleaf weeds. We detect these species in the gas-phase using real-time high resolution chemical ionization mass spectrometry (CIMS) with both acetate and iodide reagent ions. We used an Oxidative Flow Reactor to explore OH radical oxidation and photolysis of these compounds, simulating up to 5 equivalent days of atmospheric aging by OH. Use of two ionization schemes allowed for the more complete representation of the OH radical oxidation of the three pesticides. The high resolution mass spectra allows us to deduce structures of the oxidation products and identify multi-generational chemistry. In addition, we observe nitrogen oxides, as well as isocyanic acid (HNCO), from some nitrogen-containing pesticides. We present yields of species of atmospheric importance, including NOx and halogen species and consider their impact on air quality following pesticide application.

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.

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.

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

Novel and Improved Nanomaterials, Chemistries and Apparatus for Nanobiotechnology: the NACBO project.

PubMed

Bruce, Ian James

2011-02-01

This article outlines the nature and activities of the recently completed EU Framework Programme 6 Integrated Project, Novel and Improved Nanomaterials, Chemistries and Apparatus for Nanobiotechnology (NACBO). This project was designed to yield new nanomaterials, surface activation and synthetic nucleic acid chemistries, procedures and hardware for applications in forensics and diagnostics. It provides details on the project's structure and partnership along with its principal objectives and successes in terms of publications and commercial exploitation.

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

Non-OH Chemistry in Oxidation Flow Reactors for the Study of Atmospheric Chemistry Systematically Examined by Modeling

NASA Technical Reports Server (NTRS)

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.

2016-01-01

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 by

Atmospheric chemistry, sources and sinks of carbon suboxide, C3O2

NASA Astrophysics Data System (ADS)

Keßel, Stephan; Cabrera-Perez, David; Horowitz, Abraham; Veres, Patrick R.; Sander, Rolf; Taraborrelli, Domenico; Tucceri, Maria; Crowley, John N.; Pozzer, Andrea; Stönner, Christof; Vereecken, Luc; Lelieveld, Jos; Williams, Jonathan

2017-07-01

Carbon suboxide, O = C = C = C = O, has been detected in ambient air samples and has the potential to be a noxious pollutant and oxidant precursor; however, its lifetime and fate in the atmosphere are largely unknown. In this work, we collect an extensive set of studies on the atmospheric chemistry of C3O2. Rate coefficients for the reactions of C3O2 with OH radicals and ozone were determined as kOH = (2.6 ± 0.5) × 10-12 cm3 molecule-1 s-1 at 295 K (independent of pressure between ˜ 25 and 1000 mbar) and kO3 < 1.5 × 10-21 cm3 molecule-1 s-1 at 295 K. A theoretical study on the mechanisms of these reactions indicates that the sole products are CO and CO2, as observed experimentally. The UV absorption spectrum and the interaction of C3O2 with water (Henry's law solubility and hydrolysis rate constant) were also investigated, enabling its photodissociation lifetime and hydrolysis rates, respectively, to be assessed. The role of C3O2 in the atmosphere was examined using in situ measurements, an analysis of the atmospheric sources and sinks and simulation with the EMAC atmospheric chemistry-general circulation model. The results indicate sub-pptv levels at the Earth's surface, up to about 10 pptv in regions with relatively strong sources, e.g. influenced by biomass burning, and a mean lifetime of ˜ 3.2 days. These predictions carry considerable uncertainty, as more measurement data are needed to determine ambient concentrations and constrain the source strengths.

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…

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…

Global and regional environmental atmospheric chemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Newman, L.; Wang, Wenxing; Kiang, C.S.

1990-08-01

More than two hundred fifty scientists from eighteen different countries attended the first International Conference on Global and Regional Environmental Atmospheric Chemistry in the Science Hall of Friendship Hotel at Beijing, May 3--10, 1989. This volume documents the proceedings of this historical event. Following the meeting, some 173 papers were submitted for this publication. When follow up papers were not submitted the original abstract is presented. Also included are abstracts of the posters presented by the Chinese participants who could not be accommodated during the more formal sessions. We might add that this more informal session was particularly useful formore » the exchange of ideas and information between east and west. Indeed, the conference overall certainly provided an enthusiastic platform for interactions among scientists from around the world. It is our hope that these proceedings will serve as a vehicle to further enhance collaboration for joint studies of the changes in the global environment.« less

The Atmospheric Chemistry Experiment (ACE): Mission Overview

NASA Astrophysics Data System (ADS)

Bernath, P. F.; Boone, C.; Walker, K.; McLeod, S.; Nassar, R.

2003-12-01

The ACE mission goals are: (1) to measure and to understand the chemical and dynamical processes that control the distribution of ozone in the upper troposphere and stratosphere, with a particular emphasis on the Arctic region; (2) to explore the relationship between atmospheric chemistry and climate change; (3) to study the effects of biomass burning in the free troposphere; (4) to measure aerosol number density, size distribution and composition in order to reduce the uncertainties in their effects on the global energy balance. ACE will make a comprehensive set of simultaneous measurements of trace gases, thin clouds, aerosols, and temperature by solar occultation from a satellite in low earth orbit. A high inclination (74 degrees) low earth orbit (650 km) gives ACE coverage of tropical, mid-latitudes and polar regions. The solar occultation advantages are high sensitivity and self-calibration. A high-resolution (0.02 cm-1) infrared Fourier Transform Spectrometer (FTS) operating from 2 to 13 microns (750-4100 cm-1) will measure the vertical distribution of trace gases, and the meteorological variables of temperature and pressure. The ACE concept is derived from the now-retired ATMOS FTS instrument, which flew on the Space Shuttle in 1985, 1992, 1993, 1994. Climate-chemistry coupling may lead to the formation of an Arctic ozone hole. ACE will provide high quality data to confront these model predictions and will monitor polar chemistry as chlorine levels decline. The ACE-FTS can measure water vapor and HDO in the tropical tropopause region to study dehydration and strat-trop exchange. The molecular signatures of massive forest fires will evident in the ACE infrared spectra. The CO2 in our spectra can be used to either retrieve atmospheric pressure or (if the instrument pointing knowledge proves to be satisfactory) for an independent retrieval of a CO2 profile for carbon cycle science. Aerosols and clouds will be monitored using the extinction of solar radiation at

The Atmospheric Chemistry Experiment (ACE): Mission Overview

NASA Astrophysics Data System (ADS)

Bernath, P.

2003-04-01

The ACE mission goals are: (1) to measure and to understand the chemical and dynamical processes that control the distribution of ozone in the upper troposphere and stratosphere, with a particular emphasis on the Arctic region; (2) to explore the relationship between atmospheric chemistry and climate change; (3) to study the effects of biomass burning in the free troposphere; (4) to measure aerosol number density, size distribution and composition in order to reduce the uncertainties in their effects on the global energy balance. ACE will make a comprehensive set of simultaneous measurements of trace gases, thin clouds, aerosols, and temperature by solar occultation from a satellite in low earth orbit. A high inclination (74 degrees) low earth orbit (650 km) will give ACE coverage of tropical, mid-latitudes and polar regions. The solar occultation advantages are high sensitivity and self-calibration. A high-resolution (0.02 cm-1) infrared Fourier Transform Spectrometer (FTS) operating from 2 to 13 microns (750-4100 cm-1) will measure the vertical distribution of trace gases, and the meteorological variables of temperature and pressure. The ACE concept is derived from the now-retired ATMOS FTS instrument, which flew on the Space Shuttle in 1985, 1992, 1993, 1994. Climate-chemistry coupling may lead to the formation of an Arctic ozone hole. ACE will provide high quality data to confront these model predictions and will monitor polar chemistry as chlorine levels decline. The ACE-FTS can measure water vapor and HDO in the tropical tropopause region to study dehydration and strat-trop exchange. The molecular signatures of massive forest fires will evident in the ACE infrared spectra. The CO_2 in our spectra can be used to either retrieve atmospheric pressure or (if the instrument pointing knowledge proves to be satisfactory) for an independent retrieval of a CO_2 profile for carbon cycle science. Aerosols and clouds will be monitored using the extinction of solar

Do Chemistry-Climate Models Project the Same Greenhouse Gas Chemistry if Initialized with Observations of the Trace Gases: A Pre-ATom Test

NASA Astrophysics Data System (ADS)

Flynn, C. M.; Prather, M. J.; Zhu, X.; Strode, S. A.; Steenrod, S. D.; Strahan, S. E.; Lamarque, J. F.; Fiore, A. M.; Horowitz, L. W.; Mao, J.; Murray, L. T.; Shindell, D. T.

2016-12-01

Experience with climate and chemistry model intercomparison projects (MIPs) has demonstrated a diversity in model projections for the chemical greenhouse gases CH4 and O3, even when forced by the same emissions. In general, the MIPs show that models diverge in the distribution of the many key trace species that control the reactivity of the troposphere (defined here as the loss of CH4 and the production and loss of O3). Two possible sources of model differences are the chemistry-transport coupling that creates the pattern of the essential precursor species, and the calculation of reactivity. Suppose that observations, such as those planned by NASA's Atmospheric Tomography (ATom) mission, provide us with enough of a chemical climatology to constrain the modeled distribution of the essential chemical species for the current epoch. Would the models calculate the same reactivity? ATom uses the DC-8 to make in situ measurements slicing through the middle of the Pacific and Atlantic Ocean basins each season and measuring the essential trace species. Unfortunately, ATom measurements will not be available until mid-2017. Here we take the baseline chemistry from one model version (as pseudo-observations) and use it to initialize 6 other global chemistry models. In this pre-ATom MIP, we take the full chemical composition for meridional slices centered on the Dateline (UC Irvine Chemistry-Transport Model, 0.6 deg resolution, 30 layers in the troposphere). We use grid cells between 0.5 and 12 km from 60 S to 60 N to initialize grid cells in the other six models (GEOS-Chem, GFDL-AM3, GISS ModelE2, GSFC GMI, NCAR, UCI CTM). The models are then integrated for 1 day and the key chemical rates (CH4, O3) are saved. These simulations assume that the initialized parcels remain unmixed over the 24 hours, and, hence, model-to-model variations will be due to differences in photochemistry, including clouds. In addition, we assess the relative importance of the precursor species by running

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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.more » 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

ALMA observations of Titan's atmospheric chemistry and seasonal variation

NASA Astrophysics Data System (ADS)

Cordiner, Martin

2017-04-01

Titan is the largest moon of Saturn, with a thick (1.45 bar) atmosphere composed primarily of molecular nitrogen and methane. Photochemistry in Titan's upper atmosphere results in the production of a wide range of organic molecules, including hydrocarbons, nitriles and aromatics, some of which could be of pre-biotic relevance. Thus, we obtain insights into the possible molecular inventories of primitive (reducing) planetary atmospheres. Titan's atmosphere also provides a unique laboratory for testing our understanding of fundamental processes involving the chemistry and spectroscopy of complex organic molecules. In this talk, results will be presented from our studies using the Atacama Large Millimeter/submillimeter Array (ALMA) during the period 2012-2015, focussing in particular on the detection and mapping of emission from various nitrile species. By combining data from multiple ALMA observations, our spectra have reached an unprecedented sensitivity level, enabling the first spectroscopic detection and mapping of C2H3CN (vinyl cyanide) on Titan. Liquid-phase simulations of Titan's seas indicate that vinyl cyanide molecules could combine to form vesicle membranes (similar to the cells of terrestrial biology), and the astrobiological implications of this discovery will be discussed. Furthermore, ALMA observations provide instantaneous snapshot mapping of Titan's entire Earth-facing hemisphere, for gases inaccessible to previous instruments. Combined with complementary data obtained from the Cassini Saturn orbiter, as well as theoretical models and laboratory studies, our observed, seasonally variable, spatially resolved abundance patterns are capable of providing new insights into photochemical production and transport in primitive planetary atmospheres in the Solar System and beyond.

Global two dimensional chemistry model and simulation of atmospheric chemical composition

NASA Astrophysics Data System (ADS)

Zhang, Renjian; Wang, Mingxing; Zeng, Qingcun

2000-03-01

A global two-dimensional zonally averaged chemistry model is developed to study the chemi-cal composition of atmosphere. The region of the model is from 90°S to 90°N and from the ground to the altitude of 20 km with a resolution of 5° x 1 km. The wind field is residual circulation calcu-lated from diabatic rate. 34 species and 104 chemical and photochemical reactions are considered in the model. The sources of CH4, CO and NOx, which are divided into seasonal sources and non-seasonal sources, are parameterized as a function of latitude and time. The chemical composi-tion of atmosphere was simulated with emission level of CH4, CO and NOx in 1990. The results are compared with observations and other model results, showing that the model is successful to simu-late the atmospheric chemical composition and distribution of CH4.

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…

Perchlorate Formation on Mars Through Surface Radiolysis-Initiated Atmospheric Chemistry: A Potential Mechanism

NASA Technical Reports Server (NTRS)

Wilson, Eric H.; Atreya, Sushil K.; Kaiser, Ralf I.; Mahaffy, Paul R.

2016-01-01

Recent observations of the Martian surface by the Phoenix lander and the Sample Analysis at Mars indicate the presence of perchlorate (ClO4). The abundance and isotopic composition of these perchlorates suggest that the mechanisms responsible for their formation in the Martian environment may be unique in our solar system. With this in mind, we propose a potential mechanism for the production of Martian perchlorate: the radiolysis of the Martian surface by galactic cosmic rays, followed by the sublimation of chlorine oxides into the atmosphere and their subsequent synthesis to form perchloric acid (HClO4) in the atmosphere, and the surface deposition and subsequent mineralization of HClO4 in the regolith to form surface perchlorates. To evaluate the viability of this mechanism, we employ a one-dimensional chemical model, examining chlorine chemistry in the context of Martian atmospheric chemistry. Considering the chlorine oxide, OClO, we find that an OClO flux as low as 3.2 x 10(exp 7) molecules/sq cm/s sublimated into the atmosphere from the surface could produce sufficient HClO4 to explain the perchlorate concentration on Mars, assuming an accumulation depth of 30 cm and integrated over the Amazonian period. Radiolysis provides an efficient pathway for the oxidation of chlorine, bypassing the efficient Cl/HCl recycling mechanism that characterizes HClO4 formation mechanisms proposed for the Earth but not Mars.

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

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.

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

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

PubMed

Mazurek, Monica A

2002-12-01

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.

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…

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...

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…

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

PubMed

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

2012-10-07

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.

Atmospheric Circulation, Chemistry, and Infrared Spectra of Titan-like Exoplanets around Different Stellar Types

NASA Astrophysics Data System (ADS)

Lora, Juan M.; Kataria, Tiffany; Gao, Peter

2018-01-01

With the discovery of ever smaller and colder exoplanets, terrestrial worlds with hazy atmospheres must be increasingly considered. Our solar system’s Titan is a prototypical hazy planet, whose atmosphere may be representative of a large number of planets in our Galaxy. As a step toward characterizing such worlds, we present simulations of exoplanets that resemble Titan but orbit three different stellar hosts: G, K, and M dwarf stars. We use general circulation and photochemistry models to explore the circulation and chemistry of these Titan-like planets under varying stellar spectra, in all cases assuming a Titan-like insolation. Due to the strong absorption of visible light by atmospheric haze, the redder radiation accompanying later stellar types produces more isothermal stratospheres, stronger meridional temperature gradients at mbar pressures, and deeper and stronger zonal winds. In all cases, the planets’ atmospheres are strongly superrotating, but meridional circulation cells are weaker aloft under redder starlight. The photochemistry of hydrocarbon and nitrile species varies with stellar spectra, with variations in the FUV/NUV flux ratio playing an important role. Our results tentatively suggest that column haze production rates could be similar under all three hosts, implying that planets around many different stars could have similar characteristics to Titan’s atmosphere. Lastly, we present theoretical emission spectra. Overall, our study indicates that, despite important and subtle differences, the circulation and chemistry of Titan-like exoplanets are relatively insensitive to differences in the host star. These findings may be further probed with future space-based facilities, like WFIRST, LUVOIR, HabEx, and OST.

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.

Atmospheric Constraints on the Surface UV Environment of Mars at 3.9 Ga Relevant to Prebiotic Chemistry.

PubMed

Ranjan, Sukrit; Wordsworth, Robin; Sasselov, Dimitar D

2017-08-01

Recent findings suggest that Mars may have been a clement environment for the emergence of life and may even have compared favorably to Earth in this regard. These findings have revived interest in the hypothesis that prebiotically important molecules or even nascent life may have formed on Mars and been transferred to Earth. UV light plays a key role in prebiotic chemistry. Characterizing the early martian surface UV environment is key to understanding how Mars compares to Earth as a venue for prebiotic chemistry. Here, we present two-stream, multilayer calculations of the UV surface radiance on Mars at 3.9 Ga to constrain the surface UV environment as a function of atmospheric state. We explore a wide range of atmospheric pressures, temperatures, and compositions that correspond to the diversity of martian atmospheric states consistent with available constraints. We include the effects of clouds and dust. We calculate dose rates to quantify the effect of different atmospheric states on UV-sensitive prebiotic chemistry. We find that, for normative clear-sky CO 2 -H 2 O atmospheres, the UV environment on young Mars is comparable to young Earth. This similarity is robust to moderate cloud cover; thick clouds (τ cloud  ≥ 100) are required to significantly affect the martian UV environment, because cloud absorption is degenerate with atmospheric CO 2 . On the other hand, absorption from SO 2 , H 2 S, and dust is nondegenerate with CO 2 , meaning that, if these constituents build up to significant levels, surface UV fluence can be suppressed. These absorbers have spectrally variable absorption, meaning that their presence affects prebiotic pathways in different ways. In particular, high SO 2 environments may admit UV fluence that favors pathways conducive to abiogenesis over pathways unfavorable to it. However, better measurements of the spectral quantum yields of these pathways are required to evaluate this hypothesis definitively. Key Words: Radiative

Atmospheric Constraints on the Surface UV Environment of Mars at 3.9 Ga Relevant to Prebiotic Chemistry

NASA Astrophysics Data System (ADS)

Ranjan, Sukrit; Wordsworth, Robin; Sasselov, Dimitar D.

2017-08-01

Recent findings suggest that Mars may have been a clement environment for the emergence of life and may even have compared favorably to Earth in this regard. These findings have revived interest in the hypothesis that prebiotically important molecules or even nascent life may have formed on Mars and been transferred to Earth. UV light plays a key role in prebiotic chemistry. Characterizing the early martian surface UV environment is key to understanding how Mars compares to Earth as a venue for prebiotic chemistry. Here, we present two-stream, multilayer calculations of the UV surface radiance on Mars at 3.9 Ga to constrain the surface UV environment as a function of atmospheric state. We explore a wide range of atmospheric pressures, temperatures, and compositions that correspond to the diversity of martian atmospheric states consistent with available constraints. We include the effects of clouds and dust. We calculate dose rates to quantify the effect of different atmospheric states on UV-sensitive prebiotic chemistry. We find that, for normative clear-sky CO2-H2O atmospheres, the UV environment on young Mars is comparable to young Earth. This similarity is robust to moderate cloud cover; thick clouds (τcloud ≥ 100) are required to significantly affect the martian UV environment, because cloud absorption is degenerate with atmospheric CO2. On the other hand, absorption from SO2, H2S, and dust is nondegenerate with CO2, meaning that, if these constituents build up to significant levels, surface UV fluence can be suppressed. These absorbers have spectrally variable absorption, meaning that their presence affects prebiotic pathways in different ways. In particular, high SO2 environments may admit UV fluence that favors pathways conducive to abiogenesis over pathways unfavorable to it. However, better measurements of the spectral quantum yields of these pathways are required to evaluate this hypothesis definitively.

The Chemistry of Meteoric Metals in the Upper Atmosphere

NASA Astrophysics Data System (ADS)

Balasubramanian, Rajasekhar

The metals Na, Li, K, Ca and Fe have been observed around 90 km in the earth's upper atmosphere. Meteoric ablation is believed to be the source of these metals. The mesospheric chemistry of these metals and their impact on the general chemistry of the atmosphere are poorly understood. Therefore, a detailed investigation of processes affecting the gas -phase chemistry of these metals was undertaken. Both kinetic and photochemical studies were carried out using the techniques of pulsed photolysis of a suitable metal precursor and laser induced fluorescence of the resulting metal atoms. Ab initio calculations were also carried out to study the geometries of the metallic species and calculate their thermochemical properties. Kinetic investigations on the recombination reactions of the alkali metals with O_2 were performed over an extended temperature range (230-1100 K) in an attempt to understand their different seasonal behavior. The three reactions have very similar temperature dependences over the experimental temperature range. Use of the Troe formalism indicates that this dependency will continue into the mesospheric temperature range (140-240 K). The similarity suggests that differences in the temperature dependence of these reactions are not responsible for the different seasonal behavior of the alkali metals. The lower limits for the bond energies of the alkali superoxides were estimated from the kinetic decays obtained at 1100 K, and then combined with ab initio calculations to yield recommended bond energies. These values are of use in the Troe formalism and the mesospheric models. To assess the effectiveness of NaO_2 as a daytime sink, the absolute cross-section for photodissociation of NaO_2 was measured at 230 K. The photolysis rate of NaO_2 was derived above 70 km. The results indicate that above 85 km the reaction between NaO_2 and O is a more important loss term for NaO _2 than daytime photolysis and that between 80 and 65 km the photolysis of NaO_2 is

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 relativemore » 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.« less

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…

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaiser, Ralf I.; Maksyutenko, Pavlo; Ennis, Courtney

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 themore » 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.« less

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.

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.

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

ASIS v1.0: an adaptive solver for the simulation of atmospheric chemistry

NASA Astrophysics Data System (ADS)

Cariolle, Daniel; Moinat, Philippe; Teyssèdre, Hubert; Giraud, Luc; Josse, Béatrice; Lefèvre, Franck

2017-04-01

This article reports on the development and tests of the adaptive semi-implicit scheme (ASIS) solver for the simulation of atmospheric chemistry. To solve the ordinary differential equation systems associated with the time evolution of the species concentrations, ASIS adopts a one-step linearized implicit scheme with specific treatments of the Jacobian of the chemical fluxes. It conserves mass and has a time-stepping module to control the accuracy of the numerical solution. In idealized box-model simulations, ASIS gives results similar to the higher-order implicit schemes derived from the Rosenbrock's and Gear's methods and requires less computation and run time at the moderate precision required for atmospheric applications. When implemented in the MOCAGE chemical transport model and the Laboratoire de Météorologie Dynamique Mars general circulation model, the ASIS solver performs well and reveals weaknesses and limitations of the original semi-implicit solvers used by these two models. ASIS can be easily adapted to various chemical schemes and further developments are foreseen to increase its computational efficiency, and to include the computation of the concentrations of the species in aqueous-phase in addition to gas-phase chemistry.

Emission Data For Climate-Chemistry Interactions

NASA Astrophysics Data System (ADS)

Smith, S. J.

2012-12-01

Data on anthropogenic and natural emissions of reactive species are a critical input for studies of atmospheric chemistry and climate. The availability and characteristics of anthropogenic emissions data that can be used for such studies are reviewed and pathways for future work discuss Global and regional datasets for historical and future emissions are available, but their characteristics and applicability for specific studies differ. For the first time, a coordinated set of historical emissions (Lamarque et al 2010) and the future projections (van Vuurren et al. 2011) have been developed for use in the CMIP5 and ACCMIP long-term simulation comparison projects. These data have decadal resolution and were designed for long-term, global simulations. These data, however, lack finer-scale spatial and temporal detail that might be needed for some studies. Robust and timely updates of emissions data is generally lacking, although recent updates will be presented. While historical emission data is often treated as known, emissions are uncertain, even though this uncertainty is rarely quantified. Uncertainty varies by species and location. Inverse modeling is starting to indicate where emission data may be uncertain, which opens the way to improving these data overall. Further interaction between the chemistry modeling and inventory development communities are needed. Future projections are intrinsically uncertain, and while institutions and processes are in place to develop and review long-term century-scale scenarios, a need has remained for a wider range in shorter-term (e.g., several decade) projections. Emissions and scenario development communities have been working to fill this need. Communication across disciplines of the assumptions embedded in emissions projections remains a challenge. Atmospheric chemistry models are a central tool needed for studying chemistry-climate interactions. Simpler models, however, are also needed in order to examine interactions

Aqueous organic chemistry in the atmosphere: sources and chemical processing of organic aerosols.

PubMed

McNeill, V Faye

2015-02-03

Over the past decade, it has become clear that aqueous chemical processes occurring in cloud droplets and wet atmospheric particles are an important source of organic atmospheric particulate matter. Reactions of water-soluble volatile (or semivolatile) organic gases (VOCs or SVOCs) in these aqueous media lead to the formation of highly oxidized organic particulate matter (secondary organic aerosol; SOA) and key tracer species, such as organosulfates. These processes are often driven by a combination of anthropogenic and biogenic emissions, and therefore their accurate representation in models is important for effective air quality management. Despite considerable progress, mechanistic understanding of some key aqueous processes is still lacking, and these pathways are incompletely represented in 3D atmospheric chemistry and air quality models. In this article, the concepts, historical context, and current state of the science of aqueous pathways of SOA formation are discussed.

Carbon-rich Giant Planets: Atmospheric Chemistry, Thermal Inversions, Spectra, and Formation Conditions

NASA Astrophysics Data System (ADS)

Madhusudhan, Nikku; Mousis, Olivier; Johnson, Torrence V.; Lunine, Jonathan I.

2011-12-01

The recent inference of a carbon-rich atmosphere, with C/O >= 1, in the hot Jupiter WASP-12b motivates the exotic new class of carbon-rich planets (CRPs). We report a detailed study of the atmospheric chemistry and spectroscopic signatures of carbon-rich giant (CRG) planets, the possibility of thermal inversions in their atmospheres, the compositions of icy planetesimals required for their formation via core accretion, and the apportionment of ices, rock, and volatiles in their envelopes. Our results show that CRG atmospheres probe a unique region in composition space, especially at high temperature (T). For atmospheres with C/O >= 1, and T >~ 1400 K in the observable atmosphere, most of the oxygen is bound up in CO, while H2O is depleted and CH4 is enhanced by up to two or three orders of magnitude each, compared to equilibrium compositions with solar abundances (C/O = 0.54). These differences in the spectroscopically dominant species for the different C/O ratios cause equally distinct observable signatures in the spectra. As such, highly irradiated transiting giant exoplanets form ideal candidates to estimate atmospheric C/O ratios and to search for CRPs. We also find that the C/O ratio strongly affects the abundances of TiO and VO, which have been suggested to cause thermal inversions in highly irradiated hot Jupiter atmospheres. A C/O = 1 yields TiO and VO abundances of ~100 times lower than those obtained with equilibrium chemistry assuming solar abundances, at P ~ 1 bar. Such a depletion is adequate to rule out thermal inversions due to TiO/VO even in the most highly irradiated hot Jupiters, such as WASP-12b. We estimate the compositions of the protoplanetary disk, the planetesimals, and the envelope of WASP-12b, and the mass of ices dissolved in the envelope, based on the observed atmospheric abundances. Adopting stellar abundances (C/O = 0.44) for the primordial disk composition and low-temperature formation conditions (T <~ 30 K) for WASP-12b lead to a C

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.

Whole Atmosphere Community Climate Model With Lower Ionospheric Chemistry: Improved Modeling of Nitric Acid and Active Chlorine During Energetic Particle Precipitation

NASA Astrophysics Data System (ADS)

Verronen, P. T.; Andersson, M. E.; Marsh, D. R.; Kovacs, T.; Plane, J. M. C.; Päivärinta, S. M.

2016-12-01

Energetic particle precipitation (EPP) and ion chemistry affect the neutral composition of the polar middle atmosphere. For example, production of odd nitrogen and odd hydrogen during EPP events can decrease ozone by tens of percent. However, the standard ion chemistry parameterizations used in atmospheric models neglect the effects on some important species, such as nitric acid. We present WACCM-D, a variant of the Whole Atmosphere Community Climate Model, which includes a set of lower ionosphere (D-region) chemistry: 307 reactions of 20 positive ions and 21 negative ions. Compared to the Sodankylä Ion and Neutral Chemistry (SIC), a state-of-the-art 1-D model of the D-region chemistry, WACCM-D represents the lower ionosphere well. Comparison of ion concentrations between the models shows that the WACCM-D bias is typically within ±10% or less below 70 km. At 70-90 km, when strong altitude gradients in ionization rates and/or ion concentrations exist, the bias can be larger for some ions but is still within tens of percent. We also compare WACCM-D results for the January 2005 solar proton event (SPE) to those from the standard WACCM and observations from the Aura/MLS and SCISAT/ACE-FTS instruments. The results indicate that WACCM-D improves the modeling of {HNO3}, {HCl}, {ClO}, {OH}, and {NOx} during the SPE. For example, Northern Hemispheric {HNO3} from WACCM-D shows an increase by two orders of magnitude at 40-70 km compared to WACCM, reaching 2.6 ppbv, in agreement with the observations. Based on our results, WACCM-D provides a state-of-the-art global representation of D-region ion chemistry and improves modeling of EPP atmospheric effects considerably.

Impact of ozone observations on the structure of a tropical cyclone using coupled atmosphere-chemistry data assimilation

NASA Astrophysics Data System (ADS)

Lim, S.; Park, S. K.; Zupanski, M.

2015-04-01

Since the air quality forecast is related to both chemistry and meteorology, the coupled atmosphere-chemistry data assimilation (DA) system is essential to air quality forecasting. Ozone (O3) plays an important role in chemical reactions and is usually assimilated in chemical DA. In tropical cyclones (TCs), O3 usually shows a lower concentration inside the eyewall and an elevated concentration around the eye, impacting atmospheric as well as chemical variables. To identify the impact of O3 observations on TC structure, including atmospheric and chemical information, we employed the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) with an ensemble-based DA algorithm - the maximum likelihood ensemble filter (MLEF). For a TC case that occurred over the East Asia, our results indicate that the ensemble forecast is reasonable, accompanied with larger background state uncertainty over the TC, and also over eastern China. Similarly, the assimilation of O3 observations impacts atmospheric and chemical variables near the TC and over eastern China. The strongest impact on air quality in the lower troposphere was over China, likely due to the pollution advection. In the vicinity of the TC, however, the strongest impact on chemical variables adjustment was at higher levels. The impact on atmospheric variables was similar in both over China and near the TC. The analysis results are validated using several measures that include the cost function, root-mean-squared error with respect to observations, and degrees of freedom for signal (DFS). All measures indicate a positive impact of DA on the analysis - the cost function and root mean square error have decreased by 16.9 and 8.87%, respectively. In particular, the DFS indicates a strong positive impact of observations in the TC area, with a weaker maximum over northeast China.

Atmospheric Chemistry of the Carbon Capture Solvent Monoethanolamine (MEA): A Theoretical Study

NASA Astrophysics Data System (ADS)

da Silva, G.

2012-12-01

The development of amine solvent technology for carbon capture and storage has the potential to create large new sources of amines to the atmosphere. The atmospheric chemistry of amines generally, and carbon capture solvents in particular, is not well understood. We have used quantum chemistry and master equation modelling to investigate the OH radical initiated oxidation of monoethanolamine (NH2CH2CH2OH), or MEA, the archetypal carbon capture solvent. The OH radical can abstract H atoms from either carbon atom in MEA, with negative reaction barriers. Treating these reactions with a two transition state model can reliably reproduce experimental rate constants and their temperature dependence. The products of the MEA + OH reaction, the NH2CHCH2OH and NH2CH2CHOH radicals, undergo subsequent reaction with O2, which has also been studied. In both cases chemically activated reactions that bypass peroxyl radical intermediates dominate, producing 2-iminoethanol + HO2 (from NH2CHCH2OH) or aminoacetaldehyde + HO2 (from NH2CH2CHOH), making the process HOx-neutral. The operation of chemically activated reaction mechanisms has implications for the ozone forming potential of MEA. The products of MEA photo-oxidation are proposed as important species in the formation of both organic and inorganic secondary aerosols, particularly through uptake of the imine 2-iminoethanol and subsequent hydrolysis to ammonia and glycolaldehyde.

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.

Development of a Grid-Independent Geos-Chem Chemical Transport Model (v9-02) as an Atmospheric Chemistry Module for Earth System Models

NASA Technical Reports Server (NTRS)

Long, M. S.; Yantosca, R.; Nielsen, J. E; Keller, C. A.; Da Silva, A.; Sulprizio, M. P.; Pawson, S.; Jacob, D. J.

2015-01-01

The GEOS-Chem global chemical transport model (CTM), used by a large atmospheric chemistry research community, has been re-engineered to also serve as an atmospheric chemistry module for Earth system models (ESMs). This was done using an Earth System Modeling Framework (ESMF) interface that operates independently of the GEOSChem scientific code, permitting the exact same GEOSChem code to be used as an ESM module or as a standalone CTM. In this manner, the continual stream of updates contributed by the CTM user community is automatically passed on to the ESM module, which remains state of science and referenced to the latest version of the standard GEOS-Chem CTM. A major step in this re-engineering was to make GEOS-Chem grid independent, i.e., capable of using any geophysical grid specified at run time. GEOS-Chem data sockets were also created for communication between modules and with external ESM code. The grid-independent, ESMF-compatible GEOS-Chem is now the standard version of the GEOS-Chem CTM. It has been implemented as an atmospheric chemistry module into the NASA GEOS- 5 ESM. The coupled GEOS-5-GEOS-Chem system was tested for scalability and performance with a tropospheric oxidant-aerosol simulation (120 coupled species, 66 transported tracers) using 48-240 cores and message-passing interface (MPI) distributed-memory parallelization. Numerical experiments demonstrate that the GEOS-Chem chemistry module scales efficiently for the number of cores tested, with no degradation as the number of cores increases. Although inclusion of atmospheric chemistry in ESMs is computationally expensive, the excellent scalability of the chemistry module means that the relative cost goes down with increasing number of cores in a massively parallel environment.

Organics in the atmosphere: From air pollution to biogeochemical cycles and climate (Vilhelm Bjerknes Medal)

NASA Astrophysics Data System (ADS)

Kanakidou, Maria

2016-04-01

Organics are key players in the biosphere-atmosphere-climate interactions. They have also a significant anthropogenic component due to primary emissions or interactions with pollution. The organic pool in the atmosphere is a complex mixture of compounds of variable reactivity and properties, variable content in C, H, O, N and other elements depending on their origin and their history in the atmosphere. Multiphase atmospheric chemistry is known to produce organic acids with high oxygen content, like oxalic acid. This water soluble organic bi-acid is used as indicator for cloud processing and can form complexes with atmospheric Iron, affecting Iron solubility. Organics are also carriers of other nutrients like nitrogen and phosphorus. They also interact with solar radiation and with atmospheric water impacting on climate. In line with this vision for the role of organics in the atmosphere, we present results from a global 3-dimensional chemistry-transport model on the role of gaseous and particulate organics in atmospheric chemistry, accounting for multiphase chemistry and aerosol ageing in the atmosphere as well as nutrients emissions, atmospheric transport and deposition. Historical simulations and projections highlight the human impact on air quality and atmospheric deposition to the oceans. The results are put in the context of climate change. Uncertainties and implications of our findings for biogeochemical and climate modeling are discussed.

Photochemistry, Ion Chemistry, and Haze Formation in Pluto’s Atmosphere

NASA Astrophysics Data System (ADS)

Summers, Michael E.; Stern, S. A.; Gladstone, G. Randal; Young, Leslie A.; Olkin, C. B.; Weaver, H. A.; Cheng, A. F.; Strobel, D. F.; Ennico, K. A.; Kammer, J. A.; Parker, A. H.; Retherford, K. D.; Schindhelm, E.; Singer, K. N.; Steffl, A. J.; Tsang, C. C.; Versteeg, M. H.; Greathouse, T. K.; Linscott, I. R.; Tyler, L. G.; Woods, W. W.; Hinson, D. P.; Parker, J. W.; Renaud, J. P.; Ewell, M.; Lisse, Cary M.

2015-11-01

The detection of ethylene (C2H4) and acetylene (C2H2) in Pluto’s atmosphere provides important ground-truth observations for validating photochemical models of Pluto’s atmosphere. Their detection also confirms the production of precursor chemical compounds involved in the formation of tholins, which are thought to give Pluto’s surface its reddish color. Photochemical models predict many other hydrocarbon and nitrile products, currently undetected, which may also be participants in tholin production on Pluto’s surface or on atmospheric haze particles. The observed atmospheric haze layer extending to altitudes of ~140 km above Pluto’s surface, suggests a global and very robust process of atmospheric particle nucleation, growth, and sedimentation onto Pluto’s surface. The high altitude extent of the haze layer suggests that the nucleation process begins above the expected altitude range where hydrocarbons become supersaturated (below ~30 km altitude). This situation may be analogous to that in Titan’s atmosphere, wherein nucleation and aerosol growth is directly related to large negative ion production. In the case of Pluto, this means that nucleation may occur at altitudes as high as 1200 km altitude where ionization in Pluto’s atmosphere peaks. In this paper we discuss these processes and their implications for haze formation in Pluto’s atmosphere and its deposition onto Pluto’s surface. This work was supported by NASA's New Horizons project.

Building Bridges between Science Courses Using Honors Organic Chemistry Projects

ERIC Educational Resources Information Center

Hickey, Timothy; Pontrello, Jason

2016-01-01

Introductory undergraduate science courses are traditionally offered as distinct units without formalized student interaction between classes. To bridge science courses, the authors used three Honors Organic Chemistry projects paired with other science courses. The honors students delivered presentations to mainstream organic course students and…

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)

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. © 2015 The International Union of Biochemistry and Molecular Biology.

Southeast Atmosphere Studies: learning from model-observation syntheses

NASA Astrophysics Data System (ADS)

Mao, Jingqiu; Carlton, Annmarie; Cohen, Ronald C.; Brune, William H.; Brown, Steven S.; Wolfe, Glenn M.; Jimenez, Jose L.; Pye, Havala O. T.; Ng, Nga Lee; Xu, Lu; McNeill, V. Faye; Tsigaridis, Kostas; McDonald, Brian C.; Warneke, Carsten; Guenther, Alex; Alvarado, Matthew J.; de Gouw, Joost; Mickley, Loretta J.; Leibensperger, Eric M.; Mathur, Rohit; Nolte, Christopher G.; Portmann, Robert W.; Unger, Nadine; Tosca, Mika; Horowitz, Larry W.

2018-02-01

Concentrations of atmospheric trace species in the United States have changed dramatically over the past several decades in response to pollution control strategies, shifts in domestic energy policy and economics, and economic development (and resulting emission changes) elsewhere in the world. Reliable projections of the future atmosphere require models to not only accurately describe current atmospheric concentrations, but to do so by representing chemical, physical and biological processes with conceptual and quantitative fidelity. Only through incorporation of the processes controlling emissions and chemical mechanisms that represent the key transformations among reactive molecules can models reliably project the impacts of future policy, energy and climate scenarios. Efforts to properly identify and implement the fundamental and controlling mechanisms in atmospheric models benefit from intensive observation periods, during which collocated measurements of diverse, speciated chemicals in both the gas and condensed phases are obtained. The Southeast Atmosphere Studies (SAS, including SENEX, SOAS, NOMADSS and SEAC4RS) conducted during the summer of 2013 provided an unprecedented opportunity for the atmospheric modeling community to come together to evaluate, diagnose and improve the representation of fundamental climate and air quality processes in models of varying temporal and spatial scales.This paper is aimed at discussing progress in evaluating, diagnosing and improving air quality and climate modeling using comparisons to SAS observations as a guide to thinking about improvements to mechanisms and parameterizations in models. The effort focused primarily on model representation of fundamental atmospheric processes that are essential to the formation of ozone, secondary organic aerosol (SOA) and other trace species in the troposphere, with the ultimate goal of understanding the radiative impacts of these species in the southeast and elsewhere. Here we

Southeast Atmosphere Studies: learning from model-observation syntheses

PubMed Central

Mao, Jingqiu; Carlton, Annmarie; Cohen, Ronald C.; Brune, William H.; Brown, Steven S.; Wolfe, Glenn M.; Jimenez, Jose L.; Pye, Havala O. T.; Ng, Nga Lee; Xu, Lu; McNeill, V. Faye; Tsigaridis, Kostas; McDonald, Brian C.; Warneke, Carsten; Guenther, Alex; Alvarado, Matthew J.; de Gouw, Joost; Mickley, Loretta J.; Leibensperger, Eric M.; Mathur, Rohit; Nolte, Christopher G.; Portmann, Robert W.; Unger, Nadine; Tosca, Mika; Horowitz, Larry W.

2018-01-01

Concentrations of atmospheric trace species in the United States have changed dramatically over the past several decades in response to pollution control strategies, shifts in domestic energy policy and economics, and economic development (and resulting emission changes) elsewhere in the world. Reliable projections of the future atmosphere require models to not only accurately describe current atmospheric concentrations, but to do so by representing chemical, physical and biological processes with conceptual and quantitative fidelity. Only through incorporation of the processes controlling emissions and chemical mechanisms that represent the key transformations among reactive molecules can models reliably project the impacts of future policy, energy and climate scenarios. Efforts to properly identify and implement the fundamental and controlling mechanisms in atmospheric models benefit from intensive observation periods, during which collocated measurements of diverse, speciated chemicals in both the gas and condensed phases are obtained. The Southeast Atmosphere Studies (SAS, including SENEX, SOAS, NOMADSS and SEAC4RS) conducted during the summer of 2013 provided an unprecedented opportunity for the atmospheric modeling community to come together to evaluate, diagnose and improve the representation of fundamental climate and air quality processes in models of varying temporal and spatial scales. This paper is aimed at discussing progress in evaluating, diagnosing and improving air quality and climate modeling using comparisons to SAS observations as a guide to thinking about improvements to mechanisms and parameterizations in models. The effort focused primarily on model representation of fundamental atmospheric processes that are essential to the formation of ozone, secondary organic aerosol (SOA) and other trace species in the troposphere, with the ultimate goal of understanding the radiative impacts of these species in the southeast and elsewhere. Here we

Southeast Atmosphere Studies: Learning from Model-Observation Syntheses

NASA Technical Reports Server (NTRS)

Mao, Jingqiu; Carlton, Annmarie; Cohen, Ronald C.; Brune, William H.; Brown, Steven S.; Wolfe, Glenn M.; Jimenez, Jose L.; Pye, Havala O. T.; Ng, Nga Lee; Xu, Lu;

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.

Prebiotic Chemistry and Atmospheric Warming of Early Earth by an Active Young Sun

NASA Technical Reports Server (NTRS)

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

2016-01-01

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, C02 and CH, 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.

Atmospheric Research 2014 Technical Highlights

NASA Technical Reports Server (NTRS)

Platnick, Steven

2015-01-01

Atmospheric research in the Earth Sciences Division (610) consists of research and technology development programs dedicated to advancing knowledge and understanding of the atmosphere and its interaction with the climate of Earth. The Division's goals are to improve understanding of the dynamics and physical properties of precipitation, clouds, and aerosols; atmospheric chemistry, including the role of natural and anthropogenic trace species on the ozone balance in the stratosphere and the troposphere; and radiative properties of Earth's atmosphere and the influence of solar variability on the Earth's climate. Major research activities are carried out in the Mesoscale Atmospheric Processes Laboratory, the Climate and Radiation Laboratory, the Atmospheric Chemistry and Dynamics Laboratory, and the Wallops Field Support Office. The overall scope of the research covers an end-to-end process, starting with the identification of scientific problems, leading to observation requirements for remote-sensing platforms, technology and retrieval algorithm development; followed by flight projects and satellite missions; and eventually, resulting in data processing, analyses of measurements, and dissemination from flight projects and missions. Instrument scientists conceive, design, develop, and implement ultraviolet, infrared, optical, radar, laser, and lidar technology to remotely sense the atmosphere. Members of the various Laboratories conduct field measurements for satellite sensor calibration and data validation, and carry out numerous modeling activities. These modeling activities include climate model simulations, modeling the chemistry and transport of trace species on regional-to-global scales, cloud resolving models, and developing the next-generation Earth system models. Satellite missions, field campaigns, peer-reviewed publications, and successful proposals are essential at every stage of the research process to meeting our goals and maintaining leadership of the

AerChemMIP: Quantifying the effects of chemistry and aerosols in CMIP6

DOE PAGES

Collins, William J.; Lamarque, Jean -François; Schulz, Michael; ...

2017-02-09

The Aerosol Chemistry Model Intercomparison Project (AerChemMIP) is endorsed by the Coupled-Model Intercomparison Project 6 (CMIP6) and is designed to quantify the climate and air quality impacts of aerosols and chemically reactive gases. These are specifically near-term climate forcers (NTCFs: methane, tropospheric ozone and aerosols, and their precursors), nitrous oxide and ozone-depleting halocarbons. The aim of AerChemMIP is to answer four scientific questions. 1. How have anthropogenic emissions contributed to global radiative forcing and affected regional climate over the historical period? 2. How might future policies (on climate, air quality and land use) affect the abundances of NTCFs and theirmore » climate impacts? 3.How do uncertainties in historical NTCF emissions affect radiative forcing estimates? 4. How important are climate feedbacks to natural NTCF emissions, atmospheric composition, and radiative effects? These questions will be addressed through targeted simulations with CMIP6 climate models that include an interactive representation of tropospheric aerosols and atmospheric chemistry. These simulations build on the CMIP6 Diagnostic, Evaluation and Characterization of Klima (DECK) experiments, the CMIP6 historical simulations, and future projections performed elsewhere in CMIP6, allowing the contributions from aerosols and/or chemistry to be quantified. As a result, specific diagnostics are requested as part of the CMIP6 data request to highlight the chemical composition of the atmosphere, to evaluate the performance of the models, and to understand differences in behaviour between them.« less

AerChemMIP: Quantifying the effects of chemistry and aerosols in CMIP6

DOE Office of Scientific and Technical Information (OSTI.GOV)

Collins, William J.; Lamarque, Jean -François; Schulz, Michael

The Aerosol Chemistry Model Intercomparison Project (AerChemMIP) is endorsed by the Coupled-Model Intercomparison Project 6 (CMIP6) and is designed to quantify the climate and air quality impacts of aerosols and chemically reactive gases. These are specifically near-term climate forcers (NTCFs: methane, tropospheric ozone and aerosols, and their precursors), nitrous oxide and ozone-depleting halocarbons. The aim of AerChemMIP is to answer four scientific questions. 1. How have anthropogenic emissions contributed to global radiative forcing and affected regional climate over the historical period? 2. How might future policies (on climate, air quality and land use) affect the abundances of NTCFs and theirmore » climate impacts? 3.How do uncertainties in historical NTCF emissions affect radiative forcing estimates? 4. How important are climate feedbacks to natural NTCF emissions, atmospheric composition, and radiative effects? These questions will be addressed through targeted simulations with CMIP6 climate models that include an interactive representation of tropospheric aerosols and atmospheric chemistry. These simulations build on the CMIP6 Diagnostic, Evaluation and Characterization of Klima (DECK) experiments, the CMIP6 historical simulations, and future projections performed elsewhere in CMIP6, allowing the contributions from aerosols and/or chemistry to be quantified. As a result, specific diagnostics are requested as part of the CMIP6 data request to highlight the chemical composition of the atmosphere, to evaluate the performance of the models, and to understand differences in behaviour between them.« less

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.

Atmospheric Science Program. Summaries of research in FY 1994

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1995-06-01

This report provides descriptions for all projects funded by ESD under annual contracts in FY 1994. Each description contains the project`s title; three-year funding history (in thousands of dollars); the contract period over which the funding applies; the name(s) of the principal investigator(s); the institution(s) conducting the projects; and the project`s objectives, products, approach, and results to date (for most projects older than one year). Project descriptions are categorized within the report according to program areas: atmospheric chemistry, atmospheric dynamics, and support operations. Within these categories, the descriptions are ordered alphabetically by principal investigator. Each program area is preceded bymore » a brief text that defines the program area, states it goals and objectives, lists principal research questions, and identifies program managers. Appendixes provide the addresses and telephone numbers of the principal investigators and define the acronyms used.« less

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

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.

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.

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.

Project Cassini: a Saturn Orbiter/titan Probe Mission Proposal

NASA Astrophysics Data System (ADS)

Gautier, D.; Ip, W. H.

1984-12-01

Titan is the only moon in the solar system with a substantial atmosphere. The organic chemistry of its N2-CH4 atmosphere may resemble that of the earth's primitive atmosphere before life arose. The investigation of the synthesis of prebiotic molecules in Titan's atmosphere and the atmospheric and surface environments of this planet-sized moon will be the focal point of the Cassini Project proposed to the European Space Agency for an international Saturn Orbiter/Titan Probe mission.

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.

The DACCIWA project: Dynamics-aerosol-chemistry-cloud interactions in West Africa

NASA Astrophysics Data System (ADS)

Knippertz, Peter

2017-04-01

This contribution provides an overview of the EU-funded DACCIWA (Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa) project. DACCIWA consists of 16 European and African research organisations and has strong links to universities, weather services and government organisations across West Africa. The project runs from 2010 to 2018 and is built around a major international field campaign in 2016. A key motivation for DACCIWA is the expected tripling of anthropogenic emissions in southern West Africa (SWA) between 2000 and 2030, whose impacts on human health, ecosystems, food security and the regional climate are largely unknown. An integrated assessment of this problem, which is mostly due to massive economic and population growth and urbanization, is challenging due to (a) a superposition of regional effects with global climate change, (b) a strong dependence on the variable West African monsoon, (c) incomplete scientific understanding of interactions between emissions, clouds, radiation, precipitation and regional circulations, and (d) a lack of observations. DACCIWA combines measurements in the field in SWA with extensive modelling activities and work on satellite data. In particular during the main DACCIWA field campaign in June-July 2016 high-quality observations of emissions, atmospheric composition and meteorological parameters were sampled. The campaign involved three research aircraft, three ground-based supersites, enhanced radiosonde launches, and intensive measurements at urban sites in Abidjan and Cotonou. These data have already been quality-controlled and will be freely available to the research community through a database at http://baobab.sedoo.fr/DACCIWA/ after the end of the project. The resulting benchmark dataset is currently combined with a wide range of modelling and satellite-based research activities that will ultimately allow (a) an assessment of the roles of relevant physical, chemical and biological processes, (b) an improvement

The atmospheric chemistry of isoprene- and other multifunctional-nitrates

NASA Astrophysics Data System (ADS)

Perring, Anne Elizabeth

Formation of alkyl and multifunctional nitrates significantly reduces ozone production rates in their source regions, their transport and subsequent chemistry can impact secondary organic aerosol formation and NOy removal rates and they may lead to the re-release of NOx in regions far-removed from the original source. In this dissertation, the atmospheric chemistry of alkyl and multifunctional nitrates is investigated through a combination of laboratory and field measurements. In contrast to many previous studies that have focused on observations of specific individual nitrate compounds, the work described here uses a technique (Thermal Dissociation-Laser Induced Fluorescence or TD-LIF) that allows for measurements of the sum of all alkyl and multifunctional nitrates. These observations show that alkyl and multifunctional nitrates are a significant fraction of NOy in a number of different chemical regimes representing diverse hydrocarbon mixtures. In what follows, I show that their formation impacts both ozone 1 formation and NOy transport in ways that are not accounted for by currently accepted chemical mechanisms. Aircraft measurements are used to constrain nitrate yields following isoprene oxidation by OH, the atmospheric lifetimes of these nitrates, and the retention rate of the nitrate functional group upon oxidation of the initial isoprene nitrates. It is found that nitrate functionality is maintained upon further oxidation at least 75% of the time indicating that the lifetime of isoprene nitrates as a pool of compounds is considerably longer than the lifetime of the individual isoprene nitrates with respect to reaction with OH. We examine the products of NO3-initiated oxidation of isoprene in a smog-chamber, propose a detailed reaction scheme, and find that nitrates are produced with a yield of 65+/-12%, the majority of which are carbonyl nitrates. We investigate the role of alkyl and multifunctional nitrates in the Mexico City plume where they are observed

Observed variations of methane on Mars unexplained by known atmospheric chemistry and physics.

PubMed

Lefèvre, Franck; Forget, François

2009-08-06

The detection of methane on Mars has revived the possibility of past or extant life on this planet, despite the fact that an abiogenic origin is thought to be equally plausible. An intriguing aspect of the recent observations of methane on Mars is that methane concentrations appear to be locally enhanced and change with the seasons. However, methane has a photochemical lifetime of several centuries, and is therefore expected to have a spatially uniform distribution on the planet. Here we use a global climate model of Mars with coupled chemistry to examine the implications of the recently observed variations of Martian methane for our understanding of the chemistry of methane. We find that photochemistry as currently understood does not produce measurable variations in methane concentrations, even in the case of a current, local and episodic methane release. In contrast, we find that the condensation-sublimation cycle of Mars' carbon dioxide atmosphere can generate large-scale methane variations differing from those observed. In order to reproduce local methane enhancements similar to those recently reported, we show that an atmospheric lifetime of less than 200 days is necessary, even if a local source of methane is only active around the time of the observation itself. This implies an unidentified methane loss process that is 600 times faster than predicted by standard photochemistry. The existence of such a fast loss in the Martian atmosphere is difficult to reconcile with the observed distribution of other trace gas species. In the case of a destruction mechanism only active at the surface of Mars, destruction of methane must occur with an even shorter timescale of the order of approximately 1 hour to explain the observations. If recent observations of spatial and temporal variations of methane are confirmed, this would suggest an extraordinarily harsh environment for the survival of organics on the planet.

Exploring lag times between monthly atmospheric deposition and stream chemistry in Appalachian forests using cross-correlation

NASA Astrophysics Data System (ADS)

DeWalle, David R.; Boyer, Elizabeth W.; Buda, Anthony R.

2016-12-01

Forecasts of ecosystem changes due to variations in atmospheric emissions policies require a fundamental understanding of lag times between changes in chemical inputs and watershed response. Impacts of changes in atmospheric deposition in the United States have been documented using national and regional long-term environmental monitoring programs beginning several decades ago. Consequently, time series of weekly NADP atmospheric wet deposition and monthly EPA-Long Term Monitoring stream chemistry now exist for much of the Northeast which may provide insights into lag times. In this study of Appalachian forest basins, we estimated lag times for S, N and Cl by cross-correlating monthly data from four pairs of stream and deposition monitoring sites during the period from 1978 to 2012. A systems or impulse response function approach to cross-correlation was used to estimate lag times where the input deposition time series was pre-whitened using regression modeling and the stream response time series was filtered using the deposition regression model prior to cross-correlation. Cross-correlations for S were greatest at annual intervals over a relatively well-defined range of lags with the maximum correlations occurring at mean lags of 48 months. Chloride results were similar but more erratic with a mean lag of 57 months. Few high-correlation lags for N were indicated. Given the growing availability of atmospheric deposition and surface water chemistry monitoring data and our results for four Appalachian basins, further testing of cross-correlation as a method of estimating lag times on other basins appears justified.

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…

Parameterization of dust emissions in the global atmospheric chemistry-climate model EMAC: impact of nudging and soil properties

NASA Astrophysics Data System (ADS)

Astitha, M.; Lelieveld, J.; Abdel Kader, M.; Pozzer, A.; de Meij, A.

2012-11-01

Airborne desert dust influences radiative transfer, atmospheric chemistry and dynamics, as well as nutrient transport and deposition. It directly and indirectly affects climate on regional and global scales. Two versions of a parameterization scheme to compute desert dust emissions are incorporated into the atmospheric chemistry general circulation model EMAC (ECHAM5/MESSy2.41 Atmospheric Chemistry). One uses a globally uniform soil particle size distribution, whereas the other explicitly accounts for different soil textures worldwide. We have tested these two versions and investigated the sensitivity to input parameters, using remote sensing data from the Aerosol Robotic Network (AERONET) and dust concentrations and deposition measurements from the AeroCom dust benchmark database (and others). The two versions are shown to produce similar atmospheric dust loads in the N-African region, while they deviate in the Asian, Middle Eastern and S-American regions. The dust outflow from Africa over the Atlantic Ocean is accurately simulated by both schemes, in magnitude, location and seasonality. Approximately 70% of the modelled annual deposition data and 70-75% of the modelled monthly aerosol optical depth (AOD) in the Atlantic Ocean stations lay in the range 0.5 to 2 times the observations for all simulations. The two versions have similar performance, even though the total annual source differs by ~50%, which underscores the importance of transport and deposition processes (being the same for both versions). Even though the explicit soil particle size distribution is considered more realistic, the simpler scheme appears to perform better in several locations. This paper discusses the differences between the two versions of the dust emission scheme, focusing on their limitations and strengths in describing the global dust cycle and suggests possible future improvements.

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.

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.

Poster 6: Influence of traces elements in the organic chemistry of upper atmosphere of Titan

NASA Astrophysics Data System (ADS)

Mathe, Christophe; Carrasco, Nathalie; Trainer, Melissa G.; Gautier, Thomas; Gavilan, Lisseth; Dubois, David; Li, Xiang

2016-06-01

In the upper atmosphere of Titan, complex chemistry leads to the formation of organic aerosols. Since the work of Khare et al. in 1984, several experiments investigated the formation of Titan aerosols, so called tholins, in the laboratory. It has been suggested that nitrogen-containing compounds may contribute significantly to the aerosols formation process. In this study, we focused on the influence of pyridine, the simplest nitrogenous aromatic hydrocarbon, on the chemistry of Titan's atmosphere and on aerosol formation. To assess the effect of pyridine on aerosol formation chemistry, we used two different experimental setups : a capacitively coupled radio-frequency (electronic impact), and a VUV Deuterium lamp (photochemistry) in a collaboration between LATMOS (Guyancourt) and NASA-GSFC (Greenbelt), respectively. Aerosols produced with both setups were first analyzed using a FTIR-ATR (Fourier Transform Infrared spectroscopy - Attenuated Total Reflection) with a spectral range of 4000-800 cm-1 to characterize their optical properties. Next the samples were analysed using a Bruker Autoflex Speed MALDI mass spectrometer with a m/z range up to 2000 Da in order to infer their composition. Infrared spectroscopy analysis showed that tholins produced with a nitrogen-methane gas mixture (95:5) and nitrogenpyridine gas mixture (99:250ppm) present very similar spectra features. Tholins produced with a mixture of nitrogenmethane-pyridine (99:1:250ppm) do not present aliphatic CH2 or CH3 vibrational signatures. This could indicate a cyclic polymerization by a pyridine skeleton. Mass spectrometry is still in progress to confirm this.

Halogen Chemistry in the CMAQ Model

EPA Science Inventory

Halogens (iodine and bromine) emitted from oceans alter atmospheric chemistry and influence atmospheric ozone mixing ratio. We previously incorporated a representation of detailed halogen chemistry and emissions of organic and inorganic halogen species into the hemispheric Commun...

Chemical kinetics and modeling of planetary atmospheres

NASA Technical Reports Server (NTRS)

Yung, Yuk L.

1990-01-01

A unified overview is presented for chemical kinetics and chemical modeling in planetary atmospheres. The recent major advances in the understanding of the chemistry of the terrestrial atmosphere make the study of planets more interesting and relevant. A deeper understanding suggests that the important chemical cycles have a universal character that connects the different planets and ultimately link together the origin and evolution of the solar system. The completeness (or incompleteness) of the data base for chemical kinetics in planetary atmospheres will always be judged by comparison with that for the terrestrial atmosphere. In the latter case, the chemistry of H, O, N, and Cl species is well understood. S chemistry is poorly understood. In the atmospheres of Jovian planets and Titan, the C-H chemistry of simple species (containing 2 or less C atoms) is fairly well understood. The chemistry of higher hydrocarbons and the C-N, P-N chemistry is much less understood. In the atmosphere of Venus, the dominant chemistry is that of chlorine and sulfur, and very little is known about C1-S coupled chemistry. A new frontier for chemical kinetics both in the Earth and planetary atmospheres is the study of heterogeneous reactions. The formation of the ozone hole on Earth, the ubiquitous photochemical haze on Venus and in the Jovian planets and Titan all testify to the importance of heterogeneous reactions. It remains a challenge to connect the gas phase chemistry to the production of aerosols.

Research on atmospheric volcanic emissions - An overview

NASA Technical Reports Server (NTRS)

Friend, J. P.; Bandy, A. R.; Moyers, J. L.; Zoller, W. H.; Stoiber, R. E.; Torres, A. L.; Rose, W. I., Jr.; Mccormick, M. P.; Woods, D. C.

1982-01-01

Atmospheric abundances and the geochemical cycle of certain volatile compounds and elements may be largely influenced or entirely controlled by magmatic sources. However, better estimates of the magnitude and variability of volcanic emissions are required if the importance of this natural source of atmospheric constituents and the resulting effect on atmospheric chemistry are to be elucidated. The project 'Research on Atmospheric Volcanic Emissions' (RAVE) is concerned with the improvement of knowledge of both geological and chemical phenomena attending these emissions by means of comprehensive instrumentation on board a research aircraft making simultaneous measurements of plume constituents. A description is presented of the equipment and the procedures used in the RAVE field study of Mt. St. Helens' plume. An overview of the results is also provided.

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

DOE PAGES

Tilmes, S.; Mills, Mike; Niemeier, Ulrike; ...

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

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…

Insights Into Atmospheric Aqueous Organic Chemistry Through Controlled Experiments with Cloud Water Surrogates

NASA Astrophysics Data System (ADS)

Turpin, B. J.; Ramos, A.; Kirkland, J. R.; Lim, Y. B.; Seitzinger, S.

2011-12-01

There is considerable laboratory and field-based evidence that chemical processing in clouds and wet aerosols alters organic composition and contributes to the formation of secondary organic aerosol (SOA). Single-compound laboratory experiments have played an important role in developing aqueous-phase chemical mechanisms that aid prediction of SOA formation through multiphase chemistry. In this work we conduct similar experiments with cloud/fog water surrogates, to 1) evaluate to what extent the previously studied chemistry is observed in these more realistic atmospheric waters, and 2) to identify additional atmospherically-relevant precursors and products that require further study. We used filtered Camden and Pinelands, NJ rainwater as a surrogate for cloud water. OH radical (~10-12 M) was formed by photolysis of hydrogen peroxide and samples were analyzed in real-time by electrospray ionization mass spectroscopy (ESI-MS). Discrete samples were also analyzed by ion chromatography (IC) and ESI-MS after IC separation. All experiments were performed in duplicate. Standards of glyoxal, methylglyoxal and glycolaldehyde and their major aqueous oxidation products were also analyzed, and control experiments performed. Decreases in the ion abundance of many positive mode compounds and increases in the ion abundance of many negative mode compounds (e.g., organic acids) suggest that precursors are predominantly aldehydes, organic peroxides and/or alcohols. Real-time ESI mass spectra were consistent with the expected loss of methylglyoxal and subsequent formation of pyruvate, glyoxylate, and oxalate. New insights regarding other potential precursors and products will be provided.

Simulation of comprehensive chemistry and atmospheric methane lifetime in the LGM with EMAC

NASA Astrophysics Data System (ADS)

Gromov, Sergey; Steil, Benedikt

2017-04-01

Past records of atmospheric methane (CH4) abundance/isotope composition may provide a substantial insight on C exchanges in the Earth System (ES). When simulated in the climate models, CH4 helps to identify climate parameters transitions via triggering of its different (natural) sources, with a proviso that its sinks are adequately represented in the model. The latter are still a matter of large uncertainty in the studies focussing on the interpretation of CH4 evolution throughout Last Glacial Maximum (LGM), judging the conferred span of tropospheric CH4 lifetime (λ) of 3-16 yr [1-4]. In this study, we attempt to: (i) deliver the most adequate estimate of the LGM atmospheric sink of CH4 in the EMAC AC-GCM [5] equipped with the comprehensive representation of atmospheric chemistry [6], (ii) reveal the ES and CH4 emission parameters that are most influential for λ and (iii) based on these findings, suggest a parameterisation for λ that may be consistently used in climate models. In pursuing (i) we have tuned the EMAC model for simulating LGM atmospheric chemistry state, including careful revisiting of the trace gases emissions from the biosphere, biomass burning/lightning source, etc. The latter affect the key simulated component bound with λ, viz. the abundance and distribution of the hydroxyl radicals (OH) which, upon reacting with CH4, constitute its main tropospheric sink. Our preliminary findings suggest that OH is buffered in the atmosphere in a similar fashion to preindustrial climate, which in line with the recent studies employing comprehensive chemistry mechanisms (e.g., [3]). The analysis in (ii) suggests that tropospheric λ values may be qualitatively described as a convolution of values typical for zonal domain with high and low photolytic recycling rates (i.e. tropics and extra-tropics), as in the latter a dependence of the zonal average λ value on the CH4 emission strength exists. We further use the extensive diagnostic in EMAC to infer the

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…

Implementation of the chemistry module MECCA (v2.5) in the modal aerosol version of the Community Atmosphere Model component (v3.6.33) of the Community Earth System Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Long, M. S.; Keene, W. C.; Easter, Richard C.

2013-02-22

A coupled atmospheric chemistry and climate system model was developed using the modal aerosol version of the National Center for Atmospheric Research Community Atmosphere Model (modal-CAM; v3.6.33) and the Max Planck Institute for Chemistry’s Module Efficiently Calculating the Chemistry of the Atmosphere (MECCA; v2.5) to provide enhanced resolution of multiphase processes, particularly those involving inorganic halogens, and associated impacts on atmospheric composition and climate. Three Rosenbrock solvers (Ros-2, Ros-3, RODAS-3) were tested in conjunction with the basic load-balancing options available to modal-CAM (1) to establish an optimal configuration of the implicitly-solved multiphase chemistry module that maximizes both computational speed andmore » repeatability of Ros- 2 and RODAS-3 results versus Ros-3, and (2) to identify potential implementation strategies for future versions of this and similar coupled systems. RODAS-3 was faster than Ros-2 and Ros-3 with good reproduction of Ros-3 results, while Ros-2 was both slower and substantially less reproducible relative to Ros-3 results. Modal-CAM with MECCA chemistry was a factor of 15 slower than modal-CAM using standard chemistry. MECCA chemistry integration times demonstrated a systematic frequency distribution for all three solvers, and revealed that the change in run-time performance was due to a change in the frequency distribution of chemical integration times; the peak frequency was similar for all solvers. This suggests that efficient chemistry-focused load-balancing schemes can be developed that rely on the parameters of this frequency distribution.« less

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.

Projections of atmospheric mercury levels and their effect on air quality in the United States

NASA Astrophysics Data System (ADS)

Lei, H.; Wuebbles, D. J.; Liang, X.-Z.; Tao, Z.; Olsen, S.; Artz, R.; Ren, X.; Cohen, M.

2013-08-01

The individual and combined effects of global climate change and emissions changes from 2000 to 2050 on atmospheric mercury levels in the US are investigated by using the global climate-chemistry model, CAM-chem, coupled with a mercury chemistry-physics mechanism (CAM-Chem/Hg). Three future pathways from the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) are considered, with the A1FI, A1B and B1 scenarios representing the upper, middle and lower bounds of potential climate warming, respectively. The anthropogenic and biomass burning emissions of mercury are projected from the energy use assumptions in the IPCC SRES report. Natural emissions from both land and ocean sources are projected using dynamic schemes. The zonal mean surface total gaseous mercury (TGM) concentrations in the tropics and mid-latitudes of the Southern Hemisphere are projected to increase by 0.5-1.2 ng m-3 in 2050. TGM concentration increases are greater in the low latitudes than they are in the high latitudes, indicative of a larger meridional gradient than in the present day. In the A1FI scenario, TGM concentrations in 2050 are projected to increase by 2.1-4.0 ng m-3 for the eastern US and 1.4-3.0 ng m-3 for the western US. This pattern corresponds to potential increases in wet deposition of 10-14 μg m-2 for the eastern US and 2-4 μg m-2 for the western US. The increase in Hg(II) emissions tends to enhance wet deposition and hence increase the risk of higher mercury entering the hydrological cycle and ecosystems. In the B1 scenario, mercury concentrations in 2050 are similar to present level concentrations; this indicates that the domestic reduction in mercury emissions is essentially counteracted by the effects of climate warming and emissions increases in other regions. The sensitivity analyses presented show that anthropogenic emissions changes contribute 32-53% of projected mercury air concentration changes, while the independent

Model projections of atmospheric steering of Sandy-like superstorms

PubMed Central

Barnes, Elizabeth A.; Polvani, Lorenzo M.; Sobel, Adam H.

2013-01-01

Superstorm Sandy ravaged the eastern seaboard of the United States, costing a great number of lives and billions of dollars in damage. Whether events like Sandy will become more frequent as anthropogenic greenhouse gases continue to increase remains an open and complex question. Here we consider whether the persistent large-scale atmospheric patterns that steered Sandy onto the coast will become more frequent in the coming decades. Using the Coupled Model Intercomparison Project, phase 5 multimodel ensemble, we demonstrate that climate models consistently project a decrease in the frequency and persistence of the westward flow that led to Sandy’s unprecedented track, implying that future atmospheric conditions are less likely than at present to propel storms westward into the coast. PMID:24003129

Snohomish RARE project update for Tulalip Tribes | Science ...

EPA Pesticide Factsheets

Rising atmospheric CO2 due to anthropogenic emissions alters local atmospheric gas exchange rates in estuaries, causing alterations of the seawater carbonate system and reductions in pH broadly described as coastal acidification. These changes in marine chemistry have been demonstrated to negatively affect a variety of coastal and estuarine organisms. The naturally dynamic carbonate chemistry of estuaries driven by biological activity, hydrodynamic processes, and intensive biogeochemical cycling has led to uncertainty regarding the role of rising atmospheric CO2 as a driver in these systems, and the suggestion that altered atmospheric exchange may be relatively unimportant to estuarine biogeochemistry. In this presentation, we illustrate how rising atmospheric CO2 from 1765 through 2100 interacts with the observed local carbonate chemistry dynamics of a seagrass bed, and calculated how pHT, pCO2, and Ωaragonite respond. This presentation is part of an informal meeting with the Tulalip Tribes of Tulalip, WA to update them on the progress of the ORD/Region 10 RARE project in the Snohomish estuary to study drivers of coastal acidification. Multiple processes, including primary production and respiration, river runoff, cultural eutrophication, oceanic upwelling, and atmospheric exchange contribute to the characteristically dynamic carbonate conditions in these habitats, with potential interactions amongst these processes leading to coastal acidification. As a

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

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…

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…

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.

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.…

Chemistry and dynamics of the Arctic winter 2015/2016: Simulations with the Chemistry-Climate Model EMAC

NASA Astrophysics Data System (ADS)

Khosrawi, Farahnaz; Kirner, Ole; Sinnhuber, Bjoern-Martin; Ruhnke, Roland; Hoepfner, Michael; Woiwode, Wolfgang; Oelhaf, Hermann; Santee, Michelle L.; Manney, Gloria L.; Froidevaux, Lucien; Murtagh, Donal; Braesicke, Peter

2016-04-01

Model simulations of the Arctic winter 2015/2016 were performed with the atmospheric chemistry-climate model ECHAM5/MESSy Atmospheric Chemistry (EMAC) for the POLSTRACC (Polar Stratosphere in a Changing Climate) project. The POLSTRACC project is a HALO mission (High Altitude and LOng Range Research Aircraft) that aims to investigate the structure, composition and evolution of the Arctic Upper Troposphere Lower Stratosphere (UTLS) in a changing climate. Especially, the chemical and physical processes involved in Arctic stratospheric ozone depletion, transport and mixing processes in the UTLS at high latitudes, polar stratospheric clouds as well as cirrus clouds are investigated. The model simulations were performed with a resolution of T42L90, corresponding to a quadratic Gaussian grid of approximately 2.8°× 2.8° degrees in latitude and longitude, and 90 vertical layers from the surface up to 0.01 hPa (approx. 80 km). A Newtonian relaxation technique of the prognostic variables temperature, vorticity, divergence and surface pressure towards ECMWF data was applied above the boundary layer and below 10 hPa, in order to nudge the model dynamics towards the observed meteorology. During the Arctic winter 2015/2016 a stable vortex formed in early December, with a cold pool where temperatures reached below the Nitric Acid Trihydrate (NAT) existence temperature of 195 K, thus allowing Polar Stratospheric Clouds (PSCs) to form. The early winter has been exceptionally cold and satellite observations indicate that sedimenting PSC particles have lead to denitrification as well as dehydration of stratospheric layers. In this presentation an overview of the chemistry and dynamics of the Arctic winter 2015/2016 as simulated with EMAC will be given and comparisons to satellite observations such as e.g. Aura/MLS and Odin/SMR will be shown.

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.

Modeling emissions for three-dimensional atmospheric chemistry transport models.

PubMed

Matthias, Volker; Arndt, Jan A; Aulinger, Armin; Bieser, Johannes; Denier Van Der Gon, Hugo; Kranenburg, Richard; Kuenen, Jeroen; Neumann, Daniel; Pouliot, George; Quante, Markus

2018-01-24

Poor air quality is still a threat for human health in many parts of the world. In order to assess measures for emission reductions and improved air quality, three-dimensional atmospheric chemistry transport modeling systems are used in numerous research institutions and public authorities. These models need accurate emission data in appropriate spatial and temporal resolution as input. This paper reviews the most widely used emission inventories on global and regional scale and looks into the methods used to make the inventory data model ready. Shortcomings of using standard temporal profiles for each emission sector are discussed and new methods to improve the spatio-temporal distribution of the emissions are presented. These methods are often neither top-down nor bottom-up approaches but can be seen as hybrid methods that use detailed information about the emission process to derive spatially varying temporal emission profiles. These profiles are subsequently used to distribute bulk emissions like national totals on appropriate grids. The wide area of natural emissions is also summarized and the calculation methods are described. Almost all types of natural emissions depend on meteorological information, which is why they are highly variable in time and space and frequently calculated within the chemistry transport models themselves. The paper closes with an outlook for new ways to improve model ready emission data, for example by using external databases about road traffic flow or satellite data to determine actual land use or leaf area. In a world where emission patterns change rapidly, it seems appropriate to use new types of statistical and observational data to create detailed emission data sets and keep emission inventories up-to-date. Emission data is probably the most important input for chemistry transport model (CTM) systems. It needs to be provided in high temporal and spatial resolution and on a grid that is in agreement with the CTM grid. Simple

Nitrogen Fixation by Photochemistry in the Atmosphere of Titan and Implications for Prebiotic Chemistry

NASA Astrophysics Data System (ADS)

Balucani, Nadia

The observation of N-containing organic molecules and the composition of the haze aerosols, as determined by the Aerosol Collector and Pyrolyser (ACP) on-board Huygens, are clear indications that some chemistry involving nitrogen active forms and hydrocarbons is operative in the upper atmosphere of Titan. Neutral-neutral reactions involving the first electronically excited state of atomic nitrogen, N(2D), and small hydrocarbons have the right prerequisites to be among the most significant pathways to formation of nitriles, imines and other simple N-containing organic molecules. The closed-shell products methanimine, ethanimine, ketenimine, 2H-azirine and the radical products CH3N, HCCN and CH2NCH can be the intermediate molecular species that, via addition reactions, polymerization and copolymerization form the N-rich organic aerosols of Titan as well as tholins in bulk reactors simulating Titan's atmosphere.

Organic chemistry in Titan's upper atmosphere and its astrobiological consequences: I. Views towards Cassini plasma spectrometer (CAPS) and ion neutral mass spectrometer (INMS) experiments in space

NASA Astrophysics Data System (ADS)

Ali, A.; Sittler, E. C.; Chornay, D.; Rowe, B. R.; Puzzarini, C.

2015-05-01

The discovery of carbocations and carbanions by Ion Neutral Mass Spectrometer (INMS) and the Cassini Plasma Spectrometer (CAPS) instruments onboard the Cassini spacecraft in Titan's upper atmosphere is truly amazing for astrochemists and astrobiologists. In this paper we identify the reaction mechanisms for the growth of the complex macromolecules observed by the CAPS Ion Beam Spectrometer (IBS) and Electron Spectrometer (ELS). This identification is based on a recently published paper (Ali et al., 2013. Planet. Space Sci. 87, 96) which emphasizes the role of Olah's nonclassical carbonium ion chemistry in the synthesis of the organic molecules observed in Titan's thermosphere and ionosphere by INMS. The main conclusion of that work was the demonstration of the presence of the cyclopropenyl cation - the simplest Huckel's aromatic molecule - and its cyclic methyl derivatives in Titan's atmosphere at high altitudes. In this study, we present the transition from simple aromatic molecules to the complex ortho-bridged bi- and tri-cyclic hydrocarbons, e.g., CH2+ mono-substituted naphthalene and phenanthrene, as well as the ortho- and peri-bridged tri-cyclic aromatic ring, e.g., perinaphthenyl cation. These rings could further grow into tetra-cyclic and the higher order ring polymers in Titan's upper atmosphere. Contrary to the pre-Cassini observations, the nitrogen chemistry of Titan's upper atmosphere is found to be extremely rich. A variety of N-containing hydrocarbons including the N-heterocycles where a CH group in the polycyclic rings mentioned above is replaced by an N atom, e.g., CH2+ substituted derivative of quinoline (benzopyridine), are found to be dominant in Titan's upper atmosphere. The mechanisms for the formation of complex molecular anions are discussed as well. It is proposed that many closed-shell complex carbocations after their formation first, in Titan's upper atmosphere, undergo the kinetics of electron recombination to form open-shell neutral

Enabling drug discovery project decisions with integrated computational chemistry and informatics

NASA Astrophysics Data System (ADS)

Tsui, Vickie; Ortwine, Daniel F.; Blaney, Jeffrey M.

2017-03-01

Computational chemistry/informatics scientists and software engineers in Genentech Small Molecule Drug Discovery collaborate with experimental scientists in a therapeutic project-centric environment. Our mission is to enable and improve pre-clinical drug discovery design and decisions. Our goal is to deliver timely data, analysis, and modeling to our therapeutic project teams using best-in-class software tools. We describe our strategy, the organization of our group, and our approaches to reach this goal. We conclude with a summary of the interdisciplinary skills required for computational scientists and recommendations for their training.

Dynamics of the middle atmosphere as observed by the ARISE project

NASA Astrophysics Data System (ADS)

Blanc, Elisabeth

2015-04-01

The atmosphere is a complex system submitted to disturbances in a wide range of scales, including high frequency sources as volcanoes, thunderstorms, tornadoes and at larger scales, gravity waves from deep convection or wind over mountains, atmospheric tides and planetary waves. These waves affect the different atmospheric layers submitted to different temperature and wind systems which strongly control the general atmospheric circulation. The full description of gravity and planetary waves constitutes a challenge for the development of future models of atmosphere and climate. The objective of this paper is to present a review of recent advances obtained in this topic, especially in the framework of the ARISE (Atmospheric dynamics Research InfraStructure in Europe) project

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

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

Evaluation of the new EMAC-SWIFT chemistry climate model

NASA Astrophysics Data System (ADS)

Scheffler, Janice; Langematz, Ulrike; Wohltmann, Ingo; Rex, Markus

2016-04-01

It is well known that the representation of atmospheric ozone chemistry in weather and climate models is essential for a realistic simulation of the atmospheric state. Including atmospheric ozone chemistry into climate simulations is usually done by prescribing a climatological ozone field, by including a fast linear ozone scheme into the model or by using a climate model with complex interactive chemistry. While prescribed climatological ozone fields are often not aligned with the modelled dynamics, a linear ozone scheme may not be applicable for a wide range of climatological conditions. Although interactive chemistry provides a realistic representation of atmospheric chemistry such model simulations are computationally very expensive and hence not suitable for ensemble simulations or simulations with multiple climate change scenarios. A new approach to represent atmospheric chemistry in climate models which can cope with non-linearities in ozone chemistry and is applicable to a wide range of climatic states is the Semi-empirical Weighted Iterative Fit Technique (SWIFT) that is driven by reanalysis data and has been validated against observational satellite data and runs of a full Chemistry and Transport Model. SWIFT has recently been implemented into the ECHAM/MESSy (EMAC) chemistry climate model that uses a modular approach to climate modelling where individual model components can be switched on and off. Here, we show first results of EMAC-SWIFT simulations and validate these against EMAC simulations using the complex interactive chemistry scheme MECCA, and against observations.

Project ABLE: (Atmospheric Balloonborne Lidar Experiment)

NASA Astrophysics Data System (ADS)

Shepherd, O.; Aurilio, G.; Bucknam, R. D.; Hurd, A. G.; Sheehan, W. H.

1985-03-01

Project ABLE (Atmospheric Balloonborne Lidar Experiment) is part of the A.F. Geophysics Laboratory's continuing interest in developing techniques for making remote measurements of atmospheric quantities such as density, pressure, temperatures, and wind motions. The system consists of a balloonborne lidar payload designed to measure neutral molecular density as a function of altitude from ground level to 70 km. The lidar provides backscatter data at the doubled and tripled frequencies of a Nd:YAG laser, which will assist in the separation of the molecular and aerosol contributions and subsequent determination of molecular and aerosol contributions and subsequent determination of molecular density vs altitude. The object of this contract was to fabricate and operate in a field test a balloonborne lidar experiment capable of performing nighttime atmospheric density measurements up to 70 km altitude with a resolution of 150 meters. The payload included a frequency-doubled and -tripled Nd:YAG laser with outputs at 355 and 532 nm; a telescoped receiver with PMT detectors; a command-controlled optical pointing system; and support system, including thermal control, telmetry, command, and power. Successful backscatter measurements were made during field operations which included a balloon launch from Roswell, NM and a flight over the White Sands Missile Range.

Global biomass burning - Atmospheric, climatic, and biospheric implications

NASA Technical Reports Server (NTRS)

Levine, Joel S. (Editor)

1991-01-01

The present volume discusses the biomass burning (BMB) studies of the International Global Atmospheric Chemistry project, GEO satellite estimation of Amazonian BMB, remote sensing of BMB in West Africa with NOAA-AVHRR, an orbital view of the great Chinese fire of 1987, BMB's role in tropical rainforest reduction, CO and O3 measurements of BMB in the Amazon, effects of vegetation burning on the atmospheric chemistry of the Venezuelan savanna, an assessment of annually-burned biomass in Africa, and light hydrocarbon emissions from African savanna burnings. Also discussed are BMB in India, trace gas and particulate emissions from BMB in temperate ecosystems, ammonia and nitric acid emissions from wetlands and boreal forest fires, combustion emissions and satellite imagery of BMB, BMB in the perspective of the global carbon cycle, modeling trace-gas emissions from BMB, NO(x) emissions from BMB, and cloud-condensation nuclei from BMB.

Chemistry in the Troposphere.

ERIC Educational Resources Information Center

Chameides, William L.; Davis, Douglas D.

1982-01-01

Topics addressed in this review of chemistry in the troposphere (layer of atmosphere extending from earth's surface to altitude of 10-16km) include: solar radiation/winds; earth/atmosphere interface; kinetic studies of atmospheric reactions; tropospheric free-radical photochemistry; instruments for nitric oxide detection; sampling…

A study of the dissociative recombination of CaO+ with electrons: Implications for Ca chemistry in the upper atmosphere.

PubMed

Bones, D L; Gerding, M; Höffner, J; Martín, Juan Carlos Gómez; Plane, J M C

2016-12-28

The dissociative recombination of CaO + ions with electrons has been studied in a flowing afterglow reactor. CaO + was generated by the pulsed laser ablation of a Ca target, followed by entrainment in an Ar + ion/electron plasma. A kinetic model describing the gas-phase chemistry and diffusion to the reactor walls was fitted to the experimental data, yielding a rate coefficient of (3.0 ± 1.0) × 10 -7  cm 3  molecule -1  s -1 at 295 K. This result has two atmospheric implications. First, the surprising observation that the Ca + /Fe + ratio is ~8 times larger than Ca/Fe between 90 and 100 km in the atmosphere can now be explained quantitatively by the known ion-molecule chemistry of these two metals. Second, the rate of neutralization of Ca + ions in a descending sporadic E layer is fast enough to explain the often explosive growth of sporadic neutral Ca layers.

Robust impact of coupled stratospheric ozone chemistry on the response of the Austral circulation to increased greenhouse gases

NASA Astrophysics Data System (ADS)

Chiodo, G.; Polvani, L. M.

2016-12-01

Due to computational constraints, interactive stratospheric chemistry is commonly neglected in most GCMs participating in inter-comparison projects. The impact of this simplification on the modeled response to external forcings remains largely unexplored. In this work, we examine the impact of the stratospheric chemistry coupling on the SH circulation response to an abrupt quadrupling of CO2. We accomplish this with a version of the Whole Atmosphere Community Climate (WACCM) model, which allows coupling and de-coupling stratospheric chemistry, without altering any other physical parameterization. We find that the chemistry coupling in WACCM significantly reduces (by about 20%) the response of both eddy-driven mid-latitude jet and the Hadley Cell strength, without altering the surface temperature response. This behavior is linked to the representation of stratospheric ozone, and its effects on the meridional temperature gradient at the extratropical tropopause. Our results imply that neglecting stratospheric ozone chemistry results in a potential overestimation of the circulation response to GHGs. Hence, stratospheric ozone chemistry produces a substantial negative feedback on the response of the atmospheric circulation to increased greenhouse gases.

The Jovian Atmospheres

NASA Technical Reports Server (NTRS)

Allison, Michael (Editor); Travis, Larry D. (Editor)

1986-01-01

A conference on the atmosphere of Jupiter produced papers in the areas of thermal and ortho-para hydrogen structure, clouds and chemistry, atmospheric structure, global dynamics, synoptic features and processes, atmospheric dynamics, and future spaceflight opportunities. A session on the atmospheres of Uranus and Neptune was included, and the atmosphere of Saturn was discussed in several papers.

Aromatic, Alphatic, Enigmatic: The Chemistry of Titan

NASA Astrophysics Data System (ADS)

Horst, Sarah

2017-10-01

The extraordinary complexity of Titan’s atmospheric chemistry far surpasses that of any other solar system atmosphere. With its thick N2 atmosphere and stable bodies of liquid on its surface, Titan also possesses many physical processes that are similar to those that occur on Earth. The connection between Titan’s surface and atmosphere is unique in our solar system; atmospheric chemistry produces materials that are deposited on the surface and subsequently altered by surface-atmosphere interactions such as aeolian and fluvial processes resulting in the formation of extensive dune fields and expansive lakes and seas. Titan’s atmosphere is favorable for organic haze formation, which combined with the presence of some oxygen-bearing molecules indicates that Titan’s atmosphere may produce molecules of prebiotic interest. The combination of organics and liquid, in the form of water in a subsurface ocean and methane/ethane in the surface lakes and seas, means that Titan may be the ideal place in the solar system to test ideas about habitability, prebiotic chemistry, and the ubiquity and diversity of life in the universe. I will review our current understanding of chemistry on Titan forged from the powerful combination of Earth-based observations, remote sensing and in situ spacecraft measurements, laboratory experiments, and models. I will conclude with some of the questions that remain after Cassini-Huygens.

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.

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)

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.

Titan: a laboratory for prebiological organic chemistry

NASA Technical Reports Server (NTRS)

Sagan, C.; Thompson, W. R.; Khare, B. N.

1992-01-01

When we examine the atmospheres of the Jovian planets (Jupiter, Saturn, Uranus, and Neptune), the satellites in the outer solar system, comets, and even--through microwave and infrared spectroscopy--the cold dilute gas and grains between the stars, we find a rich organic chemistry, presumably abiological, not only in most of the solar system but throughout the Milky Way galaxy. In part because the composition and surface pressure of the Earth's atmosphere 4 x 10(9) years ago are unknown, laboratory experiments on prebiological organic chemistry are at best suggestive; but we can test our understanding by looking more closely at the observed extraterrestrial organic chemistry. The present Account is restricted to atmospheric organic chemistry, primarily on the large moon of Saturn. Titan is a test of our understanding of the organic chemistry of planetary atmospheres. Its atmospheric bulk composition (N2/CH4) is intermediate between the highly reducing (H2/He/CH4/NH3/H2O) atmospheres of the Jovian planets and the more oxidized (N2/CO2/H2O) atmospheres of the terrestrial planets Mars and Venus. It has long been recognized that Titan's organic chemistry may have some relevance to the events that led to the origin of life on Earth. But with Titan surface temperatures approximately equal to 94 K and pressures approximately equal to 1.6 bar, the oceans of the early Earth have no ready analogue on Titan. Nevertheless, tectonic events in the water ice-rich interior or impact melting and slow re-freezing may lead to an episodic availability of liquid water. Indeed, the latter process is the equivalent of a approximately 10(3)-year-duration shallow aqueous sea over the entire surface of Titan.

Effects of synoptic patterns on atmospheric chemistry and aerosols during the Arctic Ocean Expedition 1996

NASA Astrophysics Data System (ADS)

Nilsson, E. Douglas; Barr, Sumner

2001-12-01

The atmospheric program on the Arctic Ocean Expedition of July through September 1996 (AOE-96) was focused on aerosol climate feedback. The expedition took place close to the saddle point between a semipersistent anticyclonic ridge from near Scandinavia to the Arctic coast of eastern Siberia and a trough from the Canadian archipelago across the pole to north central Siberia. The weather varied from anticyclonic clear-sky conditions to cyclonic cloudy conditions, and 13 identifiable migratory features (frontal bands, wave disturbances) clearly influenced local weather, clouds, atmospheric transport, and chemistry. This includes an explosive polar cyclone, born at the lateral heat gradient between Greenland and the pack ice rather than between open sea and the pack ice. The synoptic scale weather systems caused the strongest variability in trace gases (O3 in particular) and aerosols, and also strong variability in the cloud cover. The formation of air masses over the pack ice primarily depends on if there is cyclonic (convergent) or anticyclonic (divergent) flow. Cyclonic flow resulted in a modified marine air mass loaded with vapor, but with low aerosol number concentrations owing to frequent clouds and fogs and efficient cloud scavenging of the aerosol. Anticyclonic flow resulted in almost continental air masses with clear sky, long residence time over the pack ice and subsidence slowly replacing the boundary layer with free tropospheric air, low vapor concentrations, but large aerosol number in lack of efficient cloud scavenging. The synoptic variability and advection from south of the ice edge were weaker than during the predecessor International Arctic Ocean Expedition in 1991 (IAOE-91), when on average the sampled air spent 55 hours over the pack ice compared to more than 120 hours during AOE-96, owing to exceptionally high cyclone activity in 1991. This caused a large difference in atmospheric transport, chemistry, and aerosols between the two expeditions.

First Measurements of the HCFC-142b Trend from Atmospheric Chemistry Experiment (ACE) Solar Occultation Spectra

NASA Technical Reports Server (NTRS)

Rinsland, Curtis P.; Chiou, Linda; Boone,Chris; Bernath, Peter; Mahieu, Emmanuel

2009-01-01

The first measurement of the HCFC-142b (CH3CClF2) trend near the tropopause has been derived from volume mixing ratio (VMR) measurements at northern and southern hemisphere mid-latitudes for the 2004-2008 time period from spaceborne solar occultation observations recorded at 0.02/cm resolution with the ACE (atmospheric chemistry experiment) Fourier transform spectrometer. The HCFC-142b molecule is currently the third most abundant HCFC (hydrochlorofluorocarbon) in the atmosphere and ACE measurements over this time span show a continuous rise in its volume mixing ratio. Monthly average measurements at northern and southern hemisphere midlatitudes have similar increase rates that are consistent with surface trend measurements for a similar time span. A mean northern hemisphere profile for the time span shows a near constant VMR at 8-20km altitude range, consistent on average for the same time span with in situ results. The nearly constant vertical VMR profile also agrees with model predictions of a long lifetime in the lower atmosphere.

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.

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,…

Development of Atmospheric Chemistry-Aerosol Transport Model for Bioavailable Iron From Dust and Combustion Source

NASA Astrophysics Data System (ADS)

Ito, A.; Feng, Y.

2009-12-01

An accurate prediction of bioavailable iron fraction for ocean biota is hampered by uncertainties in modeling soluble iron fractions in atmospheric aerosols. It has been proposed that atmospheric processing of mineral aerosols by anthropogenic pollutants may be a key pathway to transform insoluble iron into soluble forms. The dissolution of dust minerals strongly depends on solution pH, which is sensitive to the heterogeneous uptake of soluble gases by the dust particle. Due to the complexity, previous model assessments generally use a common assumption in thermodynamical equilibrium between gas and aerosol phases. Here, we compiled an emission inventory of iron from combustion and dust source, and incorporated a dust iron dissolution scheme in a global chemistry-aerosol transport model (IMPACT). We will examine and discuss the uncertainties in estimation of dissolved iron as well as comparisons of the model results with available observations.

The weathering of organic carbon and pyrite sulfur in Earth's crust and its importance for regulating atmospheric composition, seawater chemistry, and stable isotope records

NASA Astrophysics Data System (ADS)

Reinhard, C. T.; Planavsky, N.; Bolton, E. W.

2016-12-01

Earth's crust stores extremely large reservoirs of organic carbon and pyrite sulfur, and transient or secular changes in the sizes of these reservoirs have the capacity to dramatically alter atmospheric composition, climate, seawater acid-base chemistry, and the propagation of isotopic signals into the geologic record. This talk will present and discuss new quantitative approaches toward better understanding the factors that control organic carbon and pyrite sulfur weathering under a wide range of Earth surface conditions, as well as their downstream effects on seawater chemistry, stability of atmospheric pO2, and conventional interpretations of stable carbon isotope mass balance during pivotal events in Earth's biogeochemical evolution. In particular, we will focus on (1) development of a weathering-driven scaling between atmospheric pO2 and geologic carbon isotope signals that explains the relative stability of marine δ13C through time and provides a mechanism for protracted negative δ13C excursions during transient increases in atmospheric pO2; (2) experimental and theoretical approaches aimed at better understanding the role of pyrite sulfur weathering in stabilizing atmospheric pO2; and (3) the importance of redox balance in the sedimentary rock cycle for controlling the marine carbonate system and atmospheric pCO2.

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.

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'…

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.…

#IHeartChemistryNCSU: Free Choice, Content, and Elements of Science Communication as the Framework for an Introductory Organic Chemistry Project

ERIC Educational Resources Information Center

Frohock, Bram H.; Winterrowd, Samantha T.; Gallardo-Williams, Maria T.

2018-01-01

Students in a large introductory organic chemistry class were given the freedom to choose an organic compound of interest and were challenged to develop an educational object (physical or digital) designed to be shared with the broader public via social media. Analysis of the project results shows that most students appreciated the open nature of…

Chemistry of the outer planets

NASA Technical Reports Server (NTRS)

Scattergood, Thomas W.

1992-01-01

Various aspects were studied of past or present chemistry in the atmospheres of the outer planets and their satellites using lab simulations. Three areas were studied: (1) organic chemistry induced by kinetically hot hydrogen atoms in the region of Jupiter's atmosphere containing the ammonia cirrus clouds; (2) the conversion of NH3 into N2 by plasmas associated with entry of meteors and other objects into the atmosphere of early Titan; and (3) the synthesis of simple hydrocarbons and HCN by lightning in mixtures containing N2, CH4, and NH3 representing the atmospheres of Titan and the outer planets. The results showed that: (1) hot H2 atoms formed from the photodissociation of NH3 in Jupiter's atmosphere could account for some of the atmospheric chemistry in the ammonia cirrus cloud region; (2) the thermalization of hot H2 atoms in atmospheres predominated by molecular H is not as rapid as predicted by elastic collision theory; (3) the net quantum loss of NH3 in the presence of a 200 fold excess of H2 is 0.02, much higher than was expected from the amount of H2 present; (4) the conversion of NH3 into N2 in plasmas associated with infalling meteors is very efficient and rapid, and could account for most of the N2 present on Titan; (5) the yields of C2H2 and HCN from lightning induced chemistry in mixtures of CH4 and N2 is consistent with quenched thermodynamic models of the discharge core; and (6) photolysis induced by the UV light emitted by the gases in the hot plasmas may account for some, if not most, of the excess production of C2H6 and the more complex hydrocarbons.

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…

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…

Comparisons of Three-Dimensional Variational Data Assimilation and Model Output Statistics in Improving Atmospheric Chemistry Forecasts

NASA Astrophysics Data System (ADS)

Ma, Chaoqun; Wang, Tijian; Zang, Zengliang; Li, Zhijin

2018-07-01

Atmospheric chemistry models usually perform badly in forecasting wintertime air pollution because of their uncertainties. Generally, such uncertainties can be decreased effectively by techniques such as data assimilation (DA) and model output statistics (MOS). However, the relative importance and combined effects of the two techniques have not been clarified. Here, a one-month air quality forecast with the Weather Research and Forecasting-Chemistry (WRF-Chem) model was carried out in a virtually operational setup focusing on Hebei Province, China. Meanwhile, three-dimensional variational (3DVar) DA and MOS based on one-dimensional Kalman filtering were implemented separately and simultaneously to investigate their performance in improving the model forecast. Comparison with observations shows that the chemistry forecast with MOS outperforms that with 3DVar DA, which could be seen in all the species tested over the whole 72 forecast hours. Combined use of both techniques does not guarantee a better forecast than MOS only, with the improvements and degradations being small and appearing rather randomly. Results indicate that the implementation of MOS is more suitable than 3DVar DA in improving the operational forecasting ability of WRF-Chem.

Atmospheric Effects of Aviation: First Report of the Subsonic Assessment Project

NASA Technical Reports Server (NTRS)

Thompson, Anne M. (Editor); Friedl, Randall R. (Editor); Wesoky, Howard L. (Editor)

1996-01-01

This document is the first report from the Office of Aeronautics Advanced Subsonic Technology (AST) Program's Subsonic Assessment (SASS) Project. This effort, initiated in late 1993, has as its objective the assessment of the atmospheric effects of the current and predicted future aviation fleet. The two areas of impact are ozone (stratospheric and tropospheric) and radiative forcing. These are driven, respectively, by possible perturbations from aircraft emissions of NOX and soot and/or sulfur-containing particles. The report presents the major questions to which project assessments will be directed (Introduction) and the status of six programmatic elements: Emissions Scenarios, Exhaust Characterization, Near-Field Interactions, Kinetics and Laboratory Studies, Global Modeling, and Atmospheric Observations (field studies).

Tropospheric chemistry in the integrated forecasting system of ECMWF

NASA Astrophysics Data System (ADS)

Flemming, J.; Huijnen, V.; Arteta, J.; Bechtold, P.; Beljaars, A.; Blechschmidt, A.-M.; Josse, B.; Diamantakis, M.; Engelen, R. J.; Gaudel, A.; Inness, A.; Jones, L.; Katragkou, E.; Marecal, V.; Peuch, V.-H.; Richter, A.; Schultz, M. G.; Stein, O.; Tsikerdekis, A.

2014-11-01

A representation of atmospheric chemistry has been included in the Integrated Forecasting System (IFS) of the European Centre for Medium-range Weather Forecasts (ECMWF). The new chemistry modules complement the aerosol modules of the IFS for atmospheric composition, which is named C-IFS. C-IFS for chemistry supersedes a coupled system, in which the Chemical Transport Model (CTM) Model for OZone and Related chemical Tracers 3 was two-way coupled to the IFS (IFS-MOZART). This paper contains a description of the new on-line implementation, an evaluation with observations and a comparison of the performance of C-IFS with MOZART and with a re-analysis of atmospheric composition produced by IFS-MOZART within the Monitoring Atmospheric Composition and Climate (MACC) project. The chemical mechanism of C-IFS is an extended version of the Carbon Bond 2005 (CB05) chemical mechanism as implemented in the CTM Transport Model 5 (TM5). CB05 describes tropospheric chemistry with 54 species and 126 reactions. Wet deposition and lightning nitrogen monoxide (NO) emissions are modelled in C-IFS using the detailed input of the IFS physics package. A one-year simulation by C-IFS, MOZART and the MACC re-analysis is evaluated against ozonesondes, carbon monoxide (CO) aircraft profiles, European surface observations of ozone (O3), CO, sulphur dioxide (SO2) and nitrogen dioxide (NO2) as well as satellite retrievals of CO, tropospheric NO2 and formaldehyde. Anthropogenic emissions from the MACC/CityZen (MACCity) inventory and biomass burning emissions from the Global Fire Assimilation System (GFAS) data set were used in the simulations by both C-IFS and MOZART. C-IFS (CB05) showed an improved performance with respect to MOZART for CO, upper tropospheric O3, winter time SO2 and was of a similar accuracy for other evaluated species. C-IFS (CB05) is about ten times more computationally efficient than IFS-MOZART.

Tropospheric chemistry in the Integrated Forecasting System of ECMWF

NASA Astrophysics Data System (ADS)

Flemming, J.; Huijnen, V.; Arteta, J.; Bechtold, P.; Beljaars, A.; Blechschmidt, A.-M.; Diamantakis, M.; Engelen, R. J.; Gaudel, A.; Inness, A.; Jones, L.; Josse, B.; Katragkou, E.; Marecal, V.; Peuch, V.-H.; Richter, A.; Schultz, M. G.; Stein, O.; Tsikerdekis, A.

2015-04-01

A representation of atmospheric chemistry has been included in the Integrated Forecasting System (IFS) of the European Centre for Medium-Range Weather Forecasts (ECMWF). The new chemistry modules complement the aerosol modules of the IFS for atmospheric composition, which is named C-IFS. C-IFS for chemistry supersedes a coupled system in which chemical transport model (CTM) Model for OZone and Related chemical Tracers 3 was two-way coupled to the IFS (IFS-MOZART). This paper contains a description of the new on-line implementation, an evaluation with observations and a comparison of the performance of C-IFS with MOZART and with a re-analysis of atmospheric composition produced by IFS-MOZART within the Monitoring Atmospheric Composition and Climate (MACC) project. The chemical mechanism of C-IFS is an extended version of the Carbon Bond 2005 (CB05) chemical mechanism as implemented in CTM Transport Model 5 (TM5). CB05 describes tropospheric chemistry with 54 species and 126 reactions. Wet deposition and lightning nitrogen monoxide (NO) emissions are modelled in C-IFS using the detailed input of the IFS physics package. A 1 year simulation by C-IFS, MOZART and the MACC re-analysis is evaluated against ozonesondes, carbon monoxide (CO) aircraft profiles, European surface observations of ozone (O3), CO, sulfur dioxide (SO2) and nitrogen dioxide (NO2) as well as satellite retrievals of CO, tropospheric NO2 and formaldehyde. Anthropogenic emissions from the MACC/CityZen (MACCity) inventory and biomass burning emissions from the Global Fire Assimilation System (GFAS) data set were used in the simulations by both C-IFS and MOZART. C-IFS (CB05) showed an improved performance with respect to MOZART for CO, upper tropospheric O3, and wintertime SO2, and was of a similar accuracy for other evaluated species. C-IFS (CB05) is about 10 times more computationally efficient than IFS-MOZART.

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

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)

Titan's atmosphere and climate

NASA Astrophysics Data System (ADS)

Hörst, S. M.

2017-03-01

Titan is the only moon with a substantial atmosphere, the only other thick N2 atmosphere besides Earth's, the site of extraordinarily complex atmospheric chemistry that far surpasses any other solar system atmosphere, and the only other solar system body with stable liquid currently on its surface. The connection between Titan's surface and atmosphere is also unique in our solar system; atmospheric chemistry produces materials that are deposited on the surface and subsequently altered by surface-atmosphere interactions such as aeolian and fluvial processes resulting in the formation of extensive dune fields and expansive lakes and seas. Titan's atmosphere is favorable for organic haze formation, which combined with the presence of some oxygen-bearing molecules indicates that Titan's atmosphere may produce molecules of prebiotic interest. The combination of organics and liquid, in the form of water in a subsurface ocean and methane/ethane in the surface lakes and seas, means that Titan may be the ideal place in the solar system to test ideas about habitability, prebiotic chemistry, and the ubiquity and diversity of life in the universe. The Cassini-Huygens mission to the Saturn system has provided a wealth of new information allowing for study of Titan as a complex system. Here I review our current understanding of Titan's atmosphere and climate forged from the powerful combination of Earth-based observations, remote sensing and in situ spacecraft measurements, laboratory experiments, and models. I conclude with some of our remaining unanswered questions as the incredible era of exploration with Cassini-Huygens comes to an end.

Electrodynamic balance-mass spectrometry of single particles as a new platform for atmospheric chemistry research

NASA Astrophysics Data System (ADS)

Birdsall, Adam W.; Krieger, Ulrich K.; Keutsch, Frank N.

2018-01-01

New analytical techniques are needed to improve our understanding of the intertwined physical and chemical processes that affect the composition of aerosol particles in the Earth's atmosphere, such as gas-particle partitioning and homogenous or heterogeneous chemistry, and their ultimate relation to air quality and climate. We describe a new laboratory setup that couples an electrodynamic balance (EDB) to a mass spectrometer (MS). The EDB stores a single laboratory-generated particle in an electric field under atmospheric conditions for an arbitrarily long length of time. The particle is then transferred via gas flow to an ionization region that vaporizes and ionizes the analyte molecules before MS measurement. We demonstrate the feasibility of the technique by tracking evaporation of polyethylene glycol molecules and finding agreement with a kinetic model. Fitting data to the kinetic model also allows determination of vapor pressures to within a factor of 2. This EDB-MS system can be used to study fundamental chemical and physical processes involving particles that are difficult to isolate and study with other techniques. The results of such measurements can be used to improve our understanding of atmospheric particles.

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…

Advanced Modeling Techniques to Study Anthropogenic Influences on Atmospheric Chemical Budgets

NASA Technical Reports Server (NTRS)

Mathur, Rohit

1997-01-01

This research work is a collaborative effort between research groups at MCNC and the University of North Carolina at Chapel Hill. The overall objective of this research is to improve the level of understanding of the processes that determine the budgets of chemically and radiatively active compounds in the atmosphere through development and application of advanced methods for calculating the chemical change in atmospheric models. The research performed during the second year of this project focused on four major aspects: (1) The continued development and refinement of multiscale modeling techniques to address the issue of the disparate scales of the physico-chemical processes that govern the fate of atmospheric pollutants; (2) Development and application of analysis methods utilizing process and mass balance techniques to increase the interpretive powers of atmospheric models and to aid in complementary analysis of model predictions and observations; (3) Development of meteorological and emission inputs for initial application of the chemistry/transport model over the north Atlantic region; and, (4) The continued development and implementation of a totally new adaptive chemistry representation that changes the details of what is represented as the underlying conditions change.

Stream water chemistry in watersheds receiving different atmospheric inputs of H+, NH4+, NO3-, and SO42-1

USGS Publications Warehouse

Stottlemyer, R.

1997-01-01

Weekly precipitation and stream water samples were collected from small watersheds in Denali National Park, Alaska, the Fraser Experimental Forest, Colorado, Isle Royale National Park, Michigan, and the Calumet watershed on the south shore of Lake Superior, Michigan. The objective was to determine if stream water chemistry at the mouth and upstream stations reflected precipitation chemistry across a range of atmospheric inputs of H+, NH4+, NO3-, and SO42-. Volume-weighted precipitation H+, NH4+, NO3-, and SO42- concentrations varied 4 to 8 fold with concentrations highest at Calumet and lowest in Denali. Stream water chemistry varied among sites, but did not reflect precipitation chemistry. The Denali watershed, Rock Creek, had the lowest precipitation NO3- and SO42- concentrations, but the highest stream water NO3and SO42- concentrations. Among sites, the ratio of mean monthly upstream NO3- concentration to precipitation NO3- concentration declined (p 90 percent inputs) across inputs ranging from 0.12 to > 6 kg N ha-1 y-1. Factors possibly accounting for the weak or non-existent signal between stream water and precipitation ion concentrations include rapid modification of meltwater and precipitation chemistry by soil processes, and the presence of unfrozen soils which permits winter mineralization and nitrification to occur.

BOREAS (Boreal Ecosystem-Atmosphere Study): Global change and biosphere-atmosphere interactions in the boreal forest

NASA Technical Reports Server (NTRS)

Sellers, Piers J.

1991-01-01

The Boreal Ecosystems Atmosphere Study (BOREAS) is a cooperative field and analysis project involving elements of land surface climatology, tropospheric chemistry, and terrestrial ecology. The goal of the study is to understand the interactions between the boreal forest biome and the atmosphere in order to clarify their roles in global change. The study will be centered on two 20 by 20 km sites within the North American boreal forest region, located near the northern and southern limits of the biome. Studies based at these sites will be used to explore the roles of various environmental factors in controlling the extent and character of the biome. The sites will be the subject of surface, airborne, and satellite based observations which aim to improve understanding of the biological and physical processes and states which govern the exchanges of energy, water, carbon, and trace gases between boreal forest ecosystems and the atmosphere. Particular reference will be made to those processes and states that may be sensitive to global change. The study also aims to develop the use of remote sensing techniques to transfer understanding of the above process from local scales out to regional scales. The BOREAS project is being planned for 1992-1996, with a major field effort in 1994.

Prebiotic-like chemistry on Titan.

PubMed

Raulin, François; Brassé, Coralie; Poch, Olivier; Coll, Patrice

2012-08-21

Titan, the largest satellite of Saturn, is the only one in the solar system with a dense atmosphere. Mainly composed of dinitrogen with several % of methane, this atmosphere experiences complex organic processes, both in the gas and aerosol phases, which are of prebiotic interest and within an environment of astrobiological interest. This tutorial review presents the different approaches which can be followed to study such an exotic place and its chemistry: observation, theoretical modeling and experimental simulation. It describes the Cassini-Huygens mission, as an example of observational tools, and gives the new astrobiologically oriented vision of Titan which is now available by coupling the three approaches. This includes the many analogies between Titan and the Earth, in spite of the much lower temperature in the Saturn system, the complex organic chemistry in the atmosphere, from the gas to the aerosol phases, but also the potential organic chemistry on Titan's surface, and in its possible internal water ocean.

Volcanism and the atmosphere: the potential role of the atmosphere in unlocking the reactivity of volcanic emissions.

PubMed

Mather, Tamsin A

2008-12-28

Recent measurements of reactive trace gas species in volcanic plumes have offered intriguing hints at the chemistry occurring in the hot environment at volcanic vents. This has led to the recognition that volcanic vents should be regarded not only as passive sources of volcanic gases to the atmosphere, but also as 'reaction vessels' that unlock otherwise inert volcanic and atmospheric gas species. The atypical conditions created by the mixing of ambient atmosphere with the hot gases emitted from magma give rise to elevated concentrations of otherwise unexpected chemical compounds. Rapid cooling of this mixture allows these species to persist into the environment, with important consequences for gas plume chemistry and impacts. This paper discusses some examples of the implications of these high-temperature interactions in terms of nitrogen, halogen and sulphur chemistry, and their consequences in terms of the global fixed nitrogen budget, volcanically induced ozone destruction and particle fluxes to the atmosphere. Volcanically initiated atmospheric chemistry was likely to have been particularly important before biological (and latterly anthropogenic) processes started to dominate many geochemical cycles, with important consequences in terms of the evolution of the nitrogen cycle and the role of particles in modulating the Earth's climate.

Mars Atmospheric In Situ Resource Utilization Projects at the Kennedy Space Center

NASA Technical Reports Server (NTRS)

Muscatello, A. C.; Hintze, P. E.; Caraccio, A. J.; Bayliss, J. A.; Karr, L. J.; Paley, M. S.; Marone, M. J.; Gibson, T. L.; Surma, J. M.; Mansell, J. M.;

Mars Atmospheric In Situ Resource Utilization Projects at the Kennedy Space Center

NASA Technical Reports Server (NTRS)

Muscatello, Anthony; Hintze, Paul; Meier, Anne; Bayliss, Jon; Karr, Laurel; Paley, Steve; Marone, Matt; Gibson, Tracy; Surma, Jan; Mansell, Matt;

Sensitivity of Ocean Chemistry and Oxygen Change to the Uncertainty in Climate Change

NASA Astrophysics Data System (ADS)

Cao, L.; Wang, S.; Zheng, M.; Zhang, H.

2014-12-01

With increasing atmospheric CO2 and climate change, global ocean is undergoing substantial physical and biogeochemical changes. In particular, changes in ocean oxygen and carbonate chemistry have great implication for marine biota. There is considerable uncertainty in the projections of future climate change, and it is unclear how the uncertainty in climate change would affect the projection of ocean oxygen and carbonate chemistry. To examine the effect of climate change on ocean oxygen and carbonate chemistry, we used an Earth system model of intermediate complexity to perform simulations that are driven by atmospheric CO2 concentration pathway of RCP 8.5 with climate sensitivity varying from 0.0°C to 4.5 °C. Climate change affects carbonate chemistry and oxygen mainly through its impact on ocean temperature, ocean ventilation, and concentration of dissolved inorganic carbon and alkalinity. Our simulations show that climate change mitigates the decrease of carbonate ions at the ocean surface but has negligible effect on surface ocean pH. Averaged over the whole ocean, climate change acts to decrease oxygen concentration but mitigates the CO2-induced reduction of carbonate ion and pH. In our simulations, by year 2500, every degree increase of climate sensitivity warms the ocean by 0.8 °C and reduces ocean-mean dissolved oxygen concentration by 5.0%. Meanwhile, every degree increase of climate sensitivity buffers CO2-induced reduction in ocean-mean carbonate ion concentration and pH by 3.4% and 0.02 units, respectively. Our study demonstrates different sensitivities of ocean temperature, carbonate chemistry, and oxygen, in terms of both the sign and magnitude, to the amount of climate change, which have great implications for understanding the response of ocean biota to climate change.

Atmospheric Ionizing Radiation (AIR) Project Review

NASA Technical Reports Server (NTRS)

Singleterry, R. C., Jr.; Wilson, J. W.; Whitehead, A. H.; Goldhagen, P. E.

1999-01-01

The National Council on Radiation Protection and Measurement (NCRP) and the National Academy of Science (NAS) established that the uncertainty in the data and models associated with the high-altitude radiation environment could and should be reduced. In response, the National Aeronautics and Space Administration (NASA) and the U.S. Department of Energy Environmental Measurements Laboratory (EML) created the Atmospheric Ionizing Radiation (AIR) Project under the auspices of the High Speed Research (HSR) Program Office at the Langley Research Center. NASA's HSR Program was developed to address the potential of a second-generation supersonic transport. A critical element focussed on the environmental issues, including the threat to crew and passengers posed by atmospheric radiation. Various international investigators were solicited to contribute instruments to fly on an ER-2 aircraft at altitudes similar to those proposed for the High Speed Civil Transport (HSCT). A list of participating investigators, their institutions, and instruments with quantities measured is presented. The flight series took place at solar minimum (radiation maximum) with northern, southern, and east/west flights. The investigators analyzed their data and presented preliminary results at the AIR Workshop in March, 1998. A review of these results are included.

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.;

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…

General chemistry: expanding the learning outcomes and promoting interdisciplinary connections through the use of a semester-long project.

PubMed

Wenzel, Thomas J

2006-01-01

The laboratory component of a first-semester general chemistry course for science majors is described. The laboratory involves a semester-long project undertaken in a small-group format. Students are asked to examine whether plants grown in soil contaminated with lead take up more lead than those grown in uncontaminated soil. They are also asked to examine whether the acidity of the rainwater affects the amount of lead taken up by the plants. Groups are then given considerable independence in the design and implementation of the experiment. Once the seeds are planted, which takes about 4 wk into the term, several shorter experiments are integrated in before it is time to harvest and analyze the plants. The use of a project and small working groups allows for the development of a broader range of learning outcomes than occurs in a "traditional" general chemistry laboratory. The nature of these outcomes and some of the student responses to the laboratory experience are described. This particular project also works well at demonstrating the connections among chemistry, biology, geology, and environmental studies.

General Chemistry: Expanding the Learning Outcomes and Promoting Interdisciplinary Connections through the Use of a Semester-long Project

PubMed Central

Wenzel, Thomas J.

2006-01-01

The laboratory component of a first-semester general chemistry course for science majors is described. The laboratory involves a semester-long project undertaken in a small-group format. Students are asked to examine whether plants grown in soil contaminated with lead take up more lead than those grown in uncontaminated soil. They are also asked to examine whether the acidity of the rainwater affects the amount of lead taken up by the plants. Groups are then given considerable independence in the design and implementation of the experiment. Once the seeds are planted, which takes about 4 wk into the term, several shorter experiments are integrated in before it is time to harvest and analyze the plants. The use of a project and small working groups allows for the development of a broader range of learning outcomes than occurs in a “traditional” general chemistry laboratory. The nature of these outcomes and some of the student responses to the laboratory experience are described. This particular project also works well at demonstrating the connections among chemistry, biology, geology, and environmental studies. PMID:17012193

Reactions at surfaces in the atmosphere: integration of experiments and theory as necessary (but not necessarily sufficient) for predicting the physical chemistry of aerosols.

PubMed

Finlayson-Pitts, Barbara J

2009-09-28

While particles have significant deleterious impacts on human health, visibility and climate, quantitative understanding of their formation, composition and fates remains problematic. Indeed, in many cases, even qualitative understanding is lacking. One area of particular uncertainty is the nature of particle surfaces and how this determines interactions with gases in the atmosphere, including water, which is important for cloud formation and properties. The focus in this Perspective article is on some chemistry relevant to airborne particles and especially to reactions occurring on their surfaces. The intent is not to provide a comprehensive review, but rather to highlight a few selected examples of interface chemistry involving inorganic and organic species that may be important in the lower atmosphere. This includes sea salt chemistry, nitrate and nitrite ion photochemistry, organics on surfaces and heterogeneous reactions of oxides of nitrogen on proxies for airborne mineral dust and boundary layer surfaces. Emphasis is on the molecular level understanding that can only be gained by fully integrating experiment and theory to elucidate these complex systems.

Atmospheric Dynamics and Disequilibrium CO/CH4 Chemistry in the Atmosphere of the Transiting Planet HD 209458b

NASA Astrophysics Data System (ADS)

Cooper, C. S.; Showman, A. P.

2005-08-01

Chemical equilibrium considerations predict that carbon will be present in the atmosphere of HD 209458b as either CO or CH4. Assuming a solar abundance distribution of elements, the concentrations of these species are controlled by temperature and pressure only. In cooler regions, however, vigorous mass transport can occur on time scales shorter than the time scale for interconversion between CO and CH4. This results in excess [CO]/[CH4] relative to the concentrations attained in chemical equilibrium. In this work, we adapt the model of HD 209458b's meteorology used in Cooper & Showman (2005) to treat the disequilibrium chemistry of carbon. Cooper & Showman (2005) show that high-speed winds ( ˜ 4 km s-1) and large temperature contrasts ( ˜ 500 K) are plausible near the photosphere. We model CO and CH4 as passive tracers; i.e., they follow but do not disturb the fluid dynamics of the system. Our simulations will yield maps of the distribution of CO and CH4 to help guide efforts to detect the presence of carbon on this planet. Though CO was not detected on HD 209458b (Deming et al. 2005) by transmission spectroscopy, its presence in the atmosphere cannot be ruled out. For example, CO could be present over much of the dayside hemisphere but depleted near the limbs. The distribution of CO in the atmosphere is diagnostic of temperature at the pressure levels probed by various CO absorption features (Bézard & Lellouch 2002). A positive CO detection would also rule out the hypothesis that the ratio C/O > 1 on this extrasolar planet (e.g., Fortney et al. 2005). This research is supported by NSF grant AST-0307664 and NASA GSRP NGT5-50462.

DIAS Project: The establishment of a European digital upper atmosphere server

NASA Astrophysics Data System (ADS)

Belehaki, A.; Cander, Lj.; Zolesi, B.; Bremer, J.; Juren, C.; Stanislawska, I.; Dialetis, D.; Hatzopoulos, M.

2005-08-01

The main objective of DIAS (European Digital Upper Atmosphere Server) project is to develop a pan-European digital data collection on the state of the upper atmosphere, based on real-time information and historical data collections provided by most operating ionospheric stations in Europe. A DIAS system will distribute information required by various groups of users for the specification of upper atmospheric conditions over Europe suitable for nowcasting and forecasting purposes. The successful operation of the DIAS system will lead to the development of new European added-value products and services, to the effective use of observational data in operational applications and consequently to the expansion of the relevant European market.

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.

Project-Based Learning in Undergraduate Environmental Chemistry Laboratory: Using EPA Methods to Guide Student Method Development for Pesticide Quantitation

ERIC Educational Resources Information Center

Davis, Eric J.; Pauls, Steve; Dick, Jonathan

2017-01-01

Presented is a project-based learning (PBL) laboratory approach for an upper-division environmental chemistry or quantitative analysis course. In this work, a combined laboratory class of 11 environmental chemistry students developed a method based on published EPA methods for the extraction of dichlorodiphenyltrichloroethane (DDT) and its…

An Introduction to Atmospheric Physics

NASA Astrophysics Data System (ADS)

Andrews, David G.

2000-09-01

This advanced undergraduate textbook clearly details how physics can be used to understand many important aspects of atmospheric behavior. Coverage presents a broad overview of atmospheric physics, including atmospheric thermodynamics, radiative transfer, atmospheric fluid dynamics and elementary atmospheric chemistry. Armed with an understanding of these topics, the interested student will be able to grasp the essential physics behind issues of current concern, such as the enhanced greenhouse effect and associated questions of climate change, the Antarctic ozone hole and global ozone depletion, as well as more familiar processes such as the formation of raindrops and the development of weather systems. This introductory textbook is ideal for advanced undergraduates studying atmospheric physics as part of physics, meteorology or environmental science courses. It will also be useful for graduate students studying atmospheric physics for the first time and for students of applied mathematics, physical chemistry and engineering who have an interest in the atmosphere.

Students' Perceptions of a Project-Based Organic Chemistry Laboratory Environment: A Phenomenographic Approach

ERIC Educational Resources Information Center

Burrows, Nikita L.; Nowak, Montana K.; Mooring, Suazette R.

2017-01-01

Students can perceive the laboratory environment in a variety of ways that can affect what they take away from the laboratory course. This qualitative study characterizes undergraduate students' perspectives of a project-based Organic Chemistry laboratory using the theoretical framework of phenomenography. Eighteen participants were interviewed in…

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peng, Zhe; Day, Douglas A.; Ortega, Amber M.

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 O 3. 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 conditionsmore » via box modeling. The relative importance of non-OH species is less sensitive to UV light intensity than to water vapor mixing ratio (H 2O) and external OH reactivity (OHR ext), 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 O 3 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 H 2O (< 0.1%) or high OHR ext (≥ 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

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

DOE PAGES

Peng, Zhe; Day, Douglas A.; Ortega, Amber M.; ...

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 O 3. 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 conditionsmore » via box modeling. The relative importance of non-OH species is less sensitive to UV light intensity than to water vapor mixing ratio (H 2O) and external OH reactivity (OHR ext), 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 O 3 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 H 2O (< 0.1%) or high OHR ext (≥ 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

Coupled-Circulation-Chemistry Studies with the Finite-Volume CCM: Trace Gas Transport in the Tropopause Region

NASA Technical Reports Server (NTRS)

Pawson, Steven; Lin, Shian-Jiann; Rood, Richard B.; Nebuda, Sharon; Nielsen, J. Eric; Douglass, Anne R.

2000-01-01

A joint project between the Data Assimilation Office at NASA GSFC and NCAR involves linking the physical packages from the Community Climate Model (CCM) with the flux-form semi-Lagrangian dynamical core developed by Lin and Rood in the DAO. A further development of this model includes the implementation of a chemical package developed by Douglass and colleagues in the Atmospheric Chemistry and Dynamics Branch at NASA GSFC. Results from this coupled dynamics-radiation-chemistry model will be presented, focussing on trace gas transport in the tropopause region.

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),…

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,…

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…

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…

Brazil-USA Collaborative Research: Modifications by Anthropogenic Pollution of the Natural Atmospheric Chemistry and Particle Microphysics of the Tropical Rain Forest During the GoAmazon Intensive Operating Periods (IOPs)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Saewung

Manaus, a city of nearly two million people, represents an isolated urban area having a distinct urban pollution plume within the otherwise pristine Amazon Basin. The plume has high concentrations of oxides of nitrogen and sulfur, carbon monoxide, particle concentrations, and soot, among other pollutants. Critically, the distinct plume in the setting of the surrounding tropical rain forest serves as a natural laboratory to allow direct comparisons between periods of pollution influence to those of pristine conditions. The funded activity of this report is related to the Brazil-USA collaborative project during the two Intensive Operating Periods (wet season, 1 Febmore » - 31 Mar 2014; dry season, 15 Aug - 15 Oct 2014) of GoAmazon2014/5. The project addresses key science questions regarding the modification of the natural atmospheric chemistry and particle microphysics of the forest by present and future anthropogenic pollution.« less

Development of atmospheric N2O isotopomers model based on a chemistry-coupled atmospheric general circulation model

NASA Astrophysics Data System (ADS)

Ishijima, K.; Toyoda, S.; Sudo, K.; Yoshikawa, C.; Nanbu, S.; Aoki, S.; Nakazawa, T.; Yoshida, N.

2009-12-01

It is well known that isotopic information is useful to qualitatively understand cycles and constrain sources of some atmospheric species, but so far there has been no study to model N2O isotopomers throughout the atmosphere from the troposphere to the stratosphere, including realistic surface N2O isotopomers emissions. We have started to develop a model to simulate spatiotemporal variations of the atmospheric N2O isotopomers in both the troposphere and the stratosphere, based on a chemistry-coupled atmospheric general circulation model, in order to obtain more accurate quantitative understanding of the global N2O cycle. For surface emissions of the isotopomers, combination of EDGAR-based anthropogenic and soil fluxes and monthly varying GEIA oceanic fluxes are factored, using isotopic values of global total sources estimated from firn-air analyses based long-term trend of the atmospheric N2O isotopomers. Isotopic fractionations in chemical reactions are considered for photolysis and photo-oxidation of N2O in the stratosphere. The isotopic fractionation coefficients have been employed from studies based on laboratory experiments, but we also will test the coefficients determined by theoretical calculations. In terms of the global N2O isotopomer budgets, precise quantification of the sources is quite challenging, because even the spatiotemporal variabilities of N2O sources have never been adequately estimated. Therefore, we have firstly started validation of simulated isotopomer results in the stratosphere, by using the isotopomer profiles obtained by balloon observations. N2O concentration profiles are mostly well reproduced, partly because of realistic reproduction of dynamical processes by nudging with reanalysis meteorological data. However, the concentration in the polar vortex tends to be overestimated, probably due to relatively coarse wave-length resolution in photolysis calculation. Such model features also appear in the isotopomers results, which are

Stratospheric chemistry and transport

NASA Technical Reports Server (NTRS)

Prather, Michael; Garcia, Maria M.

1990-01-01

A Chemical Tracer Model (CTM) that can use wind field data generated by the General Circulation Model (GCM) is developed to implement chemistry in the three dimensional GCM of the middle atmosphere. Initially, chemical tracers with simple first order losses such as N2O are used. Successive models are to incorporate more complex ozone chemistry.

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.

Chemistry and Art.

ERIC Educational Resources Information Center

Berry, Martyn

1999-01-01

Describes a Chemistry and Art project developed for secondary students and teachers sponsored by the National Gallery and The Royal Society of Chemistry in the United Kingdom. Discusses aspects of the techniques used in creating five paintings as well as the chemistry involved in their making, deterioration, conservation, and restoration.…

Multi-model study of mercury dispersion in the atmosphere: atmospheric processes and model evaluation

NASA Astrophysics Data System (ADS)

Travnikov, Oleg; Angot, Hélène; Artaxo, Paulo; Bencardino, Mariantonia; Bieser, Johannes; D'Amore, Francesco; Dastoor, Ashu; De Simone, Francesco; Diéguez, María del Carmen; Dommergue, Aurélien; Ebinghaus, Ralf; Feng, Xin Bin; Gencarelli, Christian N.; Hedgecock, Ian M.; Magand, Olivier; Martin, Lynwill; Matthias, Volker; Mashyanov, Nikolay; Pirrone, Nicola; Ramachandran, Ramesh; Read, Katie Alana; Ryjkov, Andrei; Selin, Noelle E.; Sena, Fabrizio; Song, Shaojie; Sprovieri, Francesca; Wip, Dennis; Wängberg, Ingvar; Yang, Xin

2017-04-01

Current understanding of mercury (Hg) behavior in the atmosphere contains significant gaps. Some key characteristics of Hg processes, including anthropogenic and geogenic emissions, atmospheric chemistry, and air-surface exchange, are still poorly known. This study provides a complex analysis of processes governing Hg fate in the atmosphere involving both measured data from ground-based sites and simulation results from chemical transport models. A variety of long-term measurements of gaseous elemental Hg (GEM) and reactive Hg (RM) concentration as well as Hg wet deposition flux have been compiled from different global and regional monitoring networks. Four contemporary global-scale transport models for Hg were used, both in their state-of-the-art configurations and for a number of numerical experiments to evaluate particular processes. Results of the model simulations were evaluated against measurements. As follows from the analysis, the interhemispheric GEM gradient is largely formed by the prevailing spatial distribution of anthropogenic emissions in the Northern Hemisphere. The contributions of natural and secondary emissions enhance the south-to-north gradient, but their effect is less significant. Atmospheric chemistry has a limited effect on the spatial distribution and temporal variation of GEM concentration in surface air. In contrast, RM air concentration and wet deposition are largely defined by oxidation chemistry. The Br oxidation mechanism can reproduce successfully the observed seasonal variation of the RM / GEM ratio in the near-surface layer, but it predicts a wet deposition maximum in spring instead of in summer as observed at monitoring sites in North America and Europe. Model runs with OH chemistry correctly simulate both the periods of maximum and minimum values and the amplitude of observed seasonal variation but shift the maximum RM / GEM ratios from spring to summer. O3 chemistry does not predict significant seasonal variation of Hg

Tropospheric Halogen Chemistry

NASA Astrophysics Data System (ADS)

von Glasow, R.; Crutzen, P. J.

2003-12-01

Halogens are very reactive chemicals that are known to play an important role in anthropogenic stratospheric ozone depletion chemistry, first recognized by Molina and Rowland (1974). However, they also affect the chemistry of the troposphere. They are of special interest because they are involved in many reaction cycles that can affect the oxidation power of the atmosphere indirectly by influencing the main oxidants O3 and its photolysis product OH and directly, e.g., by reactions of the Cl radical with hydrocarbons (e.g., CH4).Already by the middle of the nineteenth century, Marchand (1852) reported the presence of bromine and iodine in rain and other natural waters. He also mentions the benefits of iodine in drinking water through the prevention of goitres and cretinism. In a prophetic monograph "Air and Rain: The Beginnings of a Chemical Climatology," Smith (1872) describes measurements of chloride in rain water, which he states to originate partly from the oceans by a process that he compares with the bursting of "soap bubbles" which produces "small vehicles" that transfer small spray droplets of seawater to the air. From deviations of the sulfate-to-chloride ratio in coastal rain compared to seawater, Smith concluded that chemical processes occur once the particles are airborne.For almost a century thereafter, however, atmospheric halogens received little attention. One exception was the work by Cauer (1939), who reported that iodine pollution has been significant in Western and Central Europe due to the inefficient burning of seaweed, causing mean gas phase atmospheric concentrations as high as or greater than 0.5 μg m-3. In his classical textbook Air Chemistry and Radioactivity, Junge (1963) devoted less than three pages to halogen gas phase chemistry, discussing chlorine and iodine. As reviewed by Eriksson (1959a, b), the main atmospheric source of halogens is sea salt, derived from the bursting of bubbles of air which are produced by ocean waves and other

Assessment of two physical parameterization schemes for desert dust emissions in an atmospheric chemistry general circulation model

NASA Astrophysics Data System (ADS)

Astitha, M.; Abdel Kader, M.; Pozzer, A.; Lelieveld, J.

2012-04-01

Atmospheric particulate matter and more specific desert dust has been the topic of numerous research studies in the past due to the wide range of impacts in the environment and climate and the uncertainty of characterizing and quantifying these impacts in a global scale. In this work we present two physical parameterizations of the desert dust production that have been incorporated in the atmospheric chemistry general circulation model EMAC (ECHAM5/MESSy2.41 Atmospheric Chemistry). The scope of this work is to assess the impact of the two physical parameterizations in the global distribution of desert dust and highlight the advantages and disadvantages of using either technique. The dust concentration and deposition has been evaluated using the AEROCOM dust dataset for the year 2000 and data from the MODIS and MISR satellites as well as sun-photometer data from the AERONET network was used to compare the modelled aerosol optical depth with observations. The implementation of the two parameterizations and the simulations using relatively high spatial resolution (T106~1.1deg) has highlighted the large spatial heterogeneity of the dust emission sources as well as the importance of the input parameters (soil size and texture, vegetation, surface wind speed). Also, sensitivity simulations with the nudging option using reanalysis data from ECMWF and without nudging have showed remarkable differences for some areas. Both parameterizations have revealed the difficulty of simulating all arid regions with the same assumptions and mechanisms. Depending on the arid region, each emission scheme performs more or less satisfactorily which leads to the necessity of treating each desert differently. Even though this is a quite different task to accomplish in a global model, some recommendations are given and ideas for future improvements.

Impact of two chemistry mechanisms fully coupled with mesoscale model on the atmospheric pollutants distribution

NASA Astrophysics Data System (ADS)

Arteta, J.; Cautenet, S.; Taghavi, M.; Audiffren, N.

Air quality models (AQM) consist of many modules (meteorology, emission, chemistry, deposition), and in some conditions such as: vicinity of clouds or aerosols plumes, complex local circulations (mountains, sea breezes), fully coupled models (online method) are necessary. In order to study the impact of lumped chemical mechanisms in AQM simulations, we examine the ability of both different chemical mechanisms: (i) simplified: Condensed Version of the MOdèle de Chimie Atmosphérique 2.2 (CV-MOCA2.2), and (ii) reference: Regional Atmospheric Chemistry Model (RACM), which are coupled online with the Regional Atmospheric Modeling Systems (RAMS) model, on the distribution of pollutants. During the ESCOMPTE experiment (Expérience sur Site pour COntraindre les Modèles de Pollution et de Transport d'Emissions) conducted over Southern France (including urban and industrial zones), Intensive observation periods (IOP) characterized by various meteorological and mixed chemical conditions are simulated. For both configurations of modeling, numerical results are compared with surface measurements (75 stations) for primary (NO x) and secondary (O 3) species. We point out the impact of the two different chemical mechanisms on the production of species involved in the oxidizing capacity such as ozone and radicals within urban and industrial areas. We highlight that both chemical mechanisms produce very similar results for the main pollutants (NO x and O 3) in three-dimensional (3D) distribution, despite large discrepancies in 0D modeling. For ozone concentration, we found sometimes small differences (5-10 ppb) between the mechanisms under study according to the cases (polluted or not). The relative difference between the two mechanisms over the whole domain is only -7% for ozone from CV-MOCA 2.2 versus RACM. When the order of magnitude is needed rather than an accurate estimate, a reduced mechanism is satisfactory. It has the advantage of running faster (four times less than CPU

Modeling atmospheric mineral aerosol chemistry to predict heterogeneous photooxidation of SO2

NASA Astrophysics Data System (ADS)

Yu, Zechen; Jang, Myoseon; Park, Jiyeon

2017-08-01

The photocatalytic ability of airborne mineral dust particles is known to heterogeneously promote SO2 oxidation, but prediction of this phenomenon is not fully taken into account by current models. In this study, the Atmospheric Mineral Aerosol Reaction (AMAR) model was developed to capture the influence of air-suspended mineral dust particles on sulfate formation in various environments. In the model, SO2 oxidation proceeds in three phases including the gas phase, the inorganic-salted aqueous phase (non-dust phase), and the dust phase. Dust chemistry is described as the absorption-desorption kinetics of SO2 and NOx (partitioning between the gas phase and the multilayer coated dust). The reaction of absorbed SO2 on dust particles occurs via two major paths: autoxidation of SO2 in open air and photocatalytic mechanisms under UV light. The kinetic mechanism of autoxidation was first leveraged using controlled indoor chamber data in the presence of Arizona Test Dust (ATD) particles without UV light, and then extended to photochemistry. With UV light, SO2 photooxidation was promoted by surface oxidants (OH radicals) that are generated via the photocatalysis of semiconducting metal oxides (electron-hole theory) of ATD particles. This photocatalytic rate constant was derived from the integration of the combinational product of the dust absorbance spectrum and wave-dependent actinic flux for the full range of wavelengths of the light source. The predicted concentrations of sulfate and nitrate using the AMAR model agreed well with outdoor chamber data that were produced under natural sunlight. For seven consecutive hours of photooxidation of SO2 in an outdoor chamber, dust chemistry at the low NOx level was attributed to 55 % of total sulfate (56 ppb SO2, 290 µg m-3 ATD, and NOx less than 5 ppb). At high NOx ( > 50 ppb of NOx with low hydrocarbons), sulfate formation was also greatly promoted by dust chemistry, but it was suppressed by the competition between NO2 and SO2

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…

Fundamental remote sensing science research program: The Scene Radiation and Atmospheric Effects Characterization Project

NASA Technical Reports Server (NTRS)

Deering, D. W.

1985-01-01

The Scene Radiation and Atmospheric Effects Characterization (SRAEC) Project was established within the NASA Fundamental Remote Sensing Science Research Program to improve our understanding of the fundamental relationships of energy interactions between the sensor and the surface target, including the effect of the atmosphere. The current studies are generalized into the following five subject areas: optical scene modeling, Earth-space radiative transfer, electromagnetic properties of surface materials, microwave scene modeling, and scatterometry studies. This report has been prepared to provide a brief overview of the SRAEC Project history and objectives and to report on the scientific findings and project accomplishments made by the nineteen principal investigators since the project's initiation just over three years ago. This annual summary report derives from the most recent annual principal investigators meeting held January 29 to 31, 1985.

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…

Impacts of changing atmospheric deposition chemistry on nitrogen and phosphorus loading to Ganga River (India).

PubMed

Pandey, Jitendra; Singh, Anand V; Singh, Ashima; Singh, Rachna

2013-08-01

Investigations on atmospheric deposition (AD) and water chemistry along a 35 km stretch of Ganga River indicated that although N:P stoichiometry of AD did not change, there were over 1.4-2.0 fold increase in AD-NO₃⁻, AD-NH₄⁺ and AD-PO₄³⁻ overtime. Concentration of dissolved inorganic-N (DIN) in river showed significant positive correlations with AD-NO₃⁻ and runoff DIN. Similarly, dissolved reactive-P (DRP) in river showed significant positive correlation with AD-PO₄³⁻ and runoff DRP. The study shows that AD has become an important source of N and P input to Ganga River.

The Atmosphere of Venus

NASA Technical Reports Server (NTRS)

Hansen, J. E. (Editor)

1975-01-01

Topics considered at the conference included the dynamics, structure, chemistry, and evolution of the Venus atmosphere, as well as cloud physics and motion. Infrared, ultraviolet, and radio occultation methods of analysis are discussed, and atmospheric models are described.

Loch Vale Watershed Project quality assurance report, 1995-1998

USGS Publications Warehouse

Allstott, E.J.; Bashkin, Michael A.; Baron, Jill S.

1999-01-01

The Loch Vale Watershed (LVWS) project was initiated in 1980 by the National Park Service with funding from the Aquatic Effects Research Program of the National Acid Precipitation Assessment Program. Initial research objectives were to understand the processes that would either mitigate or accelerate the effects of pollution on soil and surface water chemistry, and to build a record in which long-term trends could be identified and examined.It is important for all data collected in Loch Vale to meet the high standards of quality set forth in previous LVWS QA/QC reports and LVWS Methods Manuals. Given the ever-widening usage of data collected in Loch Vale, it is equally important to provide users of that data with a report assuring that all data are sound. Parameters covered in this report are the quality of meteorological measurements, hydrological measurements, surface water chemistry, and similarities in catch efficiency of two raingage types in Loch Vale for the period of 1995-1998.Routine sampling of weather conditions, precipitation chemistry, and stream/lake water chemistry began in 1982. Since then, all samples and data have been analyzed according to widely accepted and published methods. Weather data have been collected, analyzed, and stored by LVWS project personnel. Methods for the handling of meteorological data are well documented (Denning 1988, Edwards 1991, Newkirk 1995,and Allstott 1995). Precipitation chemistry has always been collected according to National Atmospheric Deposition Program protocol (Bigelow 1988), and analyzed at the Central Analytical Laboratory of the Illinois State Water Survey in Champaign, IL. QA/QC procedures of the National Atmospheric Deposition Program are well documented (Aubertin 1990). Protocols for sampling surface waters are also well documented (Newkirk 1995). Analysis of surface water chemistry has been performed using standard EPA protocol at the US Forest Service's Rocky Mt. Station Biogeochemistry Laboratory since

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…

Work on Planetary Atmospheres and Planetary Atmosphere Probes

NASA Technical Reports Server (NTRS)

Lester, Peter

1999-01-01

terms of motion not needed on Venus. When the Galileo Probe encountered Jupiter, analysis and interpretation of data commenced. The early contributions of the experiment were to define (1) the basic structure of the deep atmosphere, (2) the stability of the atmosphere, (3) the upper atmospheric profiles of density, pressure, and temperature. The next major task in the Galileo Probe project was to refine, verify and extend the analysis of the data. It was the verified, and corrected data, which indicated a dry abiabatic atmosphere within measurement accuracy. Temperature in the thermosphere was measured at 900 K. Participation in the Mars atmospheric research included: (1) work as a team member of the Mars Atmosphere Working Group, (2) contribution to the Mars Exobiology Instrument workshop, (3) asssistance in planning the Mars global network and (4) assitance in planning the Soviet-French Mars mission in 1994. This included a return to the Viking Lander parachute data to refine and improve the definition of winds between 1.5 and 4 kilometer altitude at the two entry sites. The variability of the structure of Mars atmosphere was addressed, which is known to vary with season, latitude, hemisphere and dust loading of the atmosphere. This led to work on the Pathfinder project. The probe had a deployable meteorology mast that had three temperature sensors, and a wind sensor at the tip of the mast. Work on the Titan atmospheric probe was also accomplished. This included developing an experiment proposal to the European Space Agency (ESA), which was not selected. However, as an advisor in the design and preparation of the selected experiment the researcher interacted with scientist on the Huygens Probe Atmosphere Structure Experiment. The researcher also participated in the planning for the Venus Chemical Probe. The science objectives of the probe were to resolve unanswered questions concerning the minor species chemistry of Venus' atmosphere that control cloud formation

Laser beam projection with adaptive array of fiber collimators. II. Analysis of atmospheric compensation efficiency.

PubMed

Lachinova, Svetlana L; Vorontsov, Mikhail A

2008-08-01

We analyze the potential efficiency of laser beam projection onto a remote object in atmosphere with incoherent and coherent phase-locked conformal-beam director systems composed of an adaptive array of fiber collimators. Adaptive optics compensation of turbulence-induced phase aberrations in these systems is performed at each fiber collimator. Our analysis is based on a derived expression for the atmospheric-averaged value of the mean square residual phase error as well as direct numerical simulations. Operation of both conformal-beam projection systems is compared for various adaptive system configurations characterized by the number of fiber collimators, the adaptive compensation resolution, and atmospheric turbulence conditions.

The MEarth Project: Finding the Best Targets for Atmospheric Characterization with JWST

NASA Astrophysics Data System (ADS)

Berta-Thompson, Z.

2014-04-01

If we want to directly observe the radius, orbit, mass, and atmosphere of a small, cool, habitable exoplanet, our best opportunity is to find such a planet transiting a small, cool, nearby M dwarf star. The MEarth Project is an ongoing all-sky survey for Earth-like planets transiting the closest, smallest M dwarfs in the Galaxy. MEarth aims to find good targets for atmospheric characterization with JWST and the next generation of enormous ground-based telescopes. This poster provides a status update on the MEarth Project, including the progress we've made over the past five years with 8 telescopes in the Northern hemisphere and promising early results from our new installation of 8 more telescopes in the Southern hemisphere.

Composition and chemistry of Titan's thermosphere and ionosphere.

PubMed

Vuitton, V; Yelle, R V; Lavvas, P

2009-02-28

Titan has long been known to harbour the richest atmospheric chemistry in the Solar System. Until recently, it had been believed that complex hydrocarbons and nitriles were produced through neutral chemistry that would eventually lead to the formation of micrometre sized organic aerosols. However, recent measurements by the Cassini spacecraft are drastically changing our understanding of Titan's chemistry. The Ion and Neutral Mass Spectrometer (INMS) and the Cassini Plasma Spectrometer (CAPS) revealed an extraordinary complex ionospheric composition. INMS detected roughly 50 positive ions with m/z<100 and a density higher than 0.1cm-3. CAPS provided evidence for heavy (up to 350amu) positively and negatively charged (up to 4000amu) ions. These observations all indicate that Titan's ionospheric chemistry is incredibly complex and that molecular growth starts in the upper atmosphere rather than at lower altitude. Here, we review the recent progress made on ionospheric chemistry. The presence of heavy neutrals in the upper atmosphere has been inferred as a direct consequence of the presence of complex positive ions. Benzene (C6H6) is created by ion chemistry at high altitudes and its main photolysis product, the phenyl radical (C6H5), is at the origin of the formation of aromatic species at lower altitude.

Lessons Learned from the Development and Implementation of the Atmosphere Resource Recovery and Environmental Monitoring Project

NASA Technical Reports Server (NTRS)

Roman, Monsi C.; Perry, Jay L.; Howard, David F.

2014-01-01

The Advanced Exploration Systems (AES) Program's Atmosphere Resource Recovery and Environmental Monitoring (ARREM) Project have been developing atmosphere revitalization and environmental monitoring subsystem architectures suitable for enabling sustained crewed exploration missions beyond low Earth orbit (LEO). Using the International Space Station state-of-the-art (SOA) as the technical basis, the ARREM Project has contributed to technical advances that improve affordability, reliability, and functional efficiency while reducing dependence on a ground-based logistics resupply model. Functional demonstrations have merged new process technologies and concepts with existing ISS developmental hardware and operate them in a controlled environment simulating various crew metabolic loads. The ARREM Project's strengths include access to a full complement of existing developmental hardware that perform all the core atmosphere revitalization functions, unique testing facilities to evaluate subsystem performance, and a coordinated partnering effort among six NASA field centers and industry partners to provide the innovative expertise necessary to succeed. A project overview is provided and the project management strategies that have enabled a multidiscipinary engineering team to work efficiently across project, NASA field center, and industry boundaries to achieve the project's technical goals are discussed. Lessons learned and best practices relating to the project are presented and discussed.

Meteoric Material: An Important Component of Planetary Atmospheres

NASA Technical Reports Server (NTRS)

Grebowsky, Joseph M.; Moses, Julianne I.; Pesnell, W. Dean; Vondrak, Richard R. (Technical Monitor)

2001-01-01

Interplanetary dust particles (IDPs) interact with all planetary atmospheres and leave their imprint as perturbations of the background atmospheric chemistry and structure. They lead to layers of metal ions that can become the dominant positively charged species in lower ionospheric regions. Theoretical models and radio occultation measurements provide compelling evidence that such layers exist in all planetary atmospheres. In addition IDP ablation products can affect neutral atmospheric chemistry, particularly at the outer planets where the IDPs supply oxygen compounds like water and carbon dioxide to the upper atmospheres. Aerosol or smoke particles from incomplete ablation or recondensation of ablated IDP vapors may also have a significant impact on atmospheric properties.

Direct variational data assimilation algorithm for atmospheric chemistry data with transport and transformation model

NASA Astrophysics Data System (ADS)

Penenko, Alexey; Penenko, Vladimir; Nuterman, Roman; Baklanov, Alexander; Mahura, Alexander

2015-11-01

Atmospheric chemistry dynamics is studied with convection-diffusion-reaction model. The numerical Data Assimilation algorithm presented is based on the additive-averaged splitting schemes. It carries out ''fine-grained'' variational data assimilation on the separate splitting stages with respect to spatial dimensions and processes i.e. the same measurement data is assimilated to different parts of the split model. This design has efficient implementation due to the direct data assimilation algorithms of the transport process along coordinate lines. Results of numerical experiments with chemical data assimilation algorithm of in situ concentration measurements on real data scenario have been presented. In order to construct the scenario, meteorological data has been taken from EnviroHIRLAM model output, initial conditions from MOZART model output and measurements from Airbase database.

Project-focused activity and knowledge tracker: a unified data analysis, collaboration, and workflow tool for medicinal chemistry project teams.

PubMed

Brodney, Marian D; Brosius, Arthur D; Gregory, Tracy; Heck, Steven D; Klug-McLeod, Jacquelyn L; Poss, Christopher S

2009-12-01

Advances in the field of drug discovery have brought an explosion in the quantity of data available to medicinal chemists and other project team members. New strategies and systems are needed to help these scientists to efficiently gather, organize, analyze, annotate, and share data about potential new drug molecules of interest to their project teams. Herein we describe a suite of integrated services and end-user applications that facilitate these activities throughout the medicinal chemistry design cycle. The Automated Data Presentation (ADP) and Virtual Compound Profiler (VCP) processes automate the gathering, organization, and storage of real and virtual molecules, respectively, and associated data. The Project-Focused Activity and Knowledge Tracker (PFAKT) provides a unified data analysis and collaboration environment, enhancing decision-making, improving team communication, and increasing efficiency.

Dimethylsulfide Chemistry: Annual, Seasonal, and Spatial Impacts on Sulfate

EPA Science Inventory

We incorporated oceanic emissions and atmospheric chemistry of dimethylsulfide (DMS) into the hemispheric Community Multiscale Air Quality model and performed annual model simulations without and with DMS chemistry. The model without DMS chemistry predicts higher concentrations o...

CHEMISTRY OF SILICATE ATMOSPHERES OF EVAPORATING SUPER-EARTHS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schaefer, Laura; Fegley, Bruce, E-mail: laura_s@levee.wustl.ed, 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 suchmore » 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.« less

Enviro-HIRLAM/ HARMONIE Studies in ECMWF HPC EnviroAerosols Project

NASA Astrophysics Data System (ADS)

Hansen Sass, Bent; Mahura, Alexander; Nuterman, Roman; Baklanov, Alexander; Palamarchuk, Julia; Ivanov, Serguei; Pagh Nielsen, Kristian; Penenko, Alexey; Edvardsson, Nellie; Stysiak, Aleksander Andrzej; Bostanbekov, Kairat; Amstrup, Bjarne; Yang, Xiaohua; Ruban, Igor; Bergen Jensen, Marina; Penenko, Vladimir; Nurseitov, Daniyar; Zakarin, Edige

2017-04-01

The EnviroAerosols on ECMWF HPC project (2015-2017) "Enviro-HIRLAM/ HARMONIE model research and development for online integrated meteorology-chemistry-aerosols feedbacks and interactions in weather and atmospheric composition forecasting" is aimed at analysis of importance of the meteorology-chemistry/aerosols interactions and to provide a way for development of efficient techniques for on-line coupling of numerical weather prediction and atmospheric chemical transport via process-oriented parameterizations and feedback algorithms, which will improve both the numerical weather prediction and atmospheric composition forecasts. Two main application areas of the on-line integrated modelling are considered: (i) improved numerical weather prediction with short-term feedbacks of aerosols and chemistry on formation and development of meteorological variables, and (ii) improved atmospheric composition forecasting with on-line integrated meteorological forecast and two-way feedbacks between aerosols/chemistry and meteorology. During 2015-2016 several research projects were realized. At first, the study on "On-line Meteorology-Chemistry/Aerosols Modelling and Integration for Risk Assessment: Case Studies" focused on assessment of scenarios with accidental and continuous emissions of sulphur dioxide for case studies for Atyrau (Kazakhstan) near the northern part of the Caspian Sea and metallurgical enterprises on the Kola Peninsula (Russia), with GIS integration of modelling results into the RANDOM (Risk Assessment of Nature Detriment due to Oil spill Migration) system. At second, the studies on "The sensitivity of precipitation simulations to the soot aerosol presence" & "The precipitation forecast sensitivity to data assimilation on a very high resolution domain" focused on sensitivity and changes in precipitation life-cycle under black carbon polluted conditions over Scandinavia. At third, studies on "Aerosol effects over China investigated with a high resolution

The Maryland power plant research program internet resource for precipitation chemistry data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Corio, L.A.; Jones, W.B.; Sherwell, J.

1999-07-01

The Maryland Department of Natural Resources Power Plant Research Program (PPRP) initiated a project in 1998 to make available on the World Wide Web (WWW), precipitation chemistry data from monitoring sites located in the Chesapeake Bay watershed. To that end, PPRP obtained, from various organizations, background information on atmospheric deposition monitoring programs (some of which are still on-going), as well as special studies. For those programs and studies with available precipitation chemistry data of known quality (data were not available for all programs and studies), PPRP obtained, processed, and uploaded the data to its WWW site (www.versar.com/pprp/features/aciddep/aciddep.htm). These data canmore » either be viewed on the web site or downloaded as a zipped file in either comma-delimited or Excel spreadsheet format. PPRP also provides descriptions of the monitoring programs/studies, including information on measurement methods and quality assurance procedures, where available. For the few monitoring programs (e.g., NADP) with existing web sites that allow on-line access to data, PPRP provides links to these sites. PPRP currently is working with the National Oceanic and Atmospheric Administration (NOAA) Air Resources Laboratory (ARL) in a cooperative effort to make more precipitation chemistry data easily available to the scientific community.« less

Biomass burning in the tropics: Impact on atmospheric chemistry and biogeochemical cycles

DOE Office of Scientific and Technical Information (OSTI.GOV)

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{sup 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 burningmore » 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% of the nitrogen in the biomass fuel can be released as molecular nitrogen. This pyrodenitrification process causes a sizable loss of fixed nitrogen in tropical ecosystems, in the range of 10 to 20 teragrams per year (1 teragram = 10{sup 12} grams).« less

Implementation of an Online Chemistry Model to a Large Eddy Simulation Model (PALM-4U0

NASA Astrophysics Data System (ADS)

Mauder, M.; Khan, B.; Forkel, R.; Banzhaf, S.; Russo, E. E.; Sühring, M.; Kanani-Sühring, F.; Raasch, S.; Ketelsen, K.

2017-12-01

Large Eddy Simulation (LES) models permit to resolve relevant scales of turbulent motion, so that these models can capture the inherent unsteadiness of atmospheric turbulence. However, LES models are so far hardly applied for urban air quality studies, in particular chemical transformation of pollutants. In this context, BMBF (Bundesministerium für Bildung und Forschung) funded a joint project, MOSAIK (Modellbasierte Stadtplanung und Anwendung im Klimawandel / Model-based city planning and application in climate change) with the main goal to develop a new highly efficient urban climate model (UCM) that also includes atmospheric chemical processes. The state-of-the-art LES model PALM; Maronga et al, 2015, Geosci. Model Dev., 8, doi:10.5194/gmd-8-2515-2015), has been used as a core model for the new UCM named as PALM-4U. For the gas phase chemistry, a fully coupled 'online' chemistry model has been implemented into PALM. The latest version of the Kinetic PreProcessor (KPP) Version 2.3, has been utilized for the numerical integration of chemical species. Due to the high computational demands of the LES model, compromises in the description of chemical processes are required. Therefore, a reduced chemistry mechanism, which includes only major pollutants namely O3, NO, NO2, CO, a highly simplified VOC chemistry and a small number of products have been implemented. This work shows preliminary results of the advection, and chemical transformation of atmospheric pollutants. Non-cyclic boundaries have been used for inflow and outflow in east-west directions while periodic boundary conditions have been implemented to the south-north lateral boundaries. For practical applications, our approach is to go beyond the simulation of single street canyons to chemical transformation, advection and deposition of air pollutants in the larger urban canopy. Tests of chemistry schemes and initial studies of chemistry-turbulence, transport and transformations are presented.

From Freshman Student to Upper-Secondary School Teacher in Chemistry: A New Approach with Projects and Group Work.

ERIC Educational Resources Information Center

Josephsen, Jens

1985-01-01

A special five and one-half year program for training upper secondary school chemistry teachers has been developed and tested over the past decade at Roskilde University near Copenhagen. The program (which emphasizes project work) and a student project on epoxy glue are described. Program graduates are generally problem-oriented and…

Investigating expanded chemistry in CMAQ clouds

EPA Science Inventory

Clouds and fogs significantly impact the amount, composition, and spatial distribution of gas and particulate atmospheric species, not least of which through the chemistry that occurs in cloud droplets.ﾠ Atmospheric sulfate is an important component of fine aerosol mass an...

Modeling the Explicit Chemistry of Anthropogenic and Biogenic Organic Aerosols

DOE Office of Scientific and Technical Information (OSTI.GOV)

Madronich, Sasha

2015-12-09

The atmospheric burden of Secondary Organic Aerosols (SOA) remains one of the most important yet uncertain aspects of the radiative forcing of climate. This grant focused on improving our quantitative understanding of SOA formation and evolution, by developing, applying, and improving a highly detailed model of atmospheric organic chemistry, the Generation of Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A) model. Eleven (11) publications have resulted from this grant.

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

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.

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…

Parameterization of plume chemistry into large-scale atmospheric models: Application to aircraft NOx emissions

NASA Astrophysics Data System (ADS)

Cariolle, D.; Caro, D.; Paoli, R.; Hauglustaine, D. A.; CuéNot, B.; Cozic, A.; Paugam, R.

2009-10-01

A method is presented to parameterize the impact of the nonlinear chemical reactions occurring in the plume generated by concentrated NOx sources into large-scale models. The resulting plume parameterization is implemented into global models and used to evaluate the impact of aircraft emissions on the atmospheric chemistry. Compared to previous approaches that rely on corrected emissions or corrective factors to account for the nonlinear chemical effects, the present parameterization is based on the representation of the plume effects via a fuel tracer and a characteristic lifetime during which the nonlinear interactions between species are important and operate via rates of conversion for the NOx species and an effective reaction rates for O3. The implementation of this parameterization insures mass conservation and allows the transport of emissions at high concentrations in plume form by the model dynamics. Results from the model simulations of the impact on atmospheric ozone of aircraft NOx emissions are in rather good agreement with previous work. It is found that ozone production is decreased by 10 to 25% in the Northern Hemisphere with the largest effects in the north Atlantic flight corridor when the plume effects on the global-scale chemistry are taken into account. These figures are consistent with evaluations made with corrected emissions, but regional differences are noticeable owing to the possibility offered by this parameterization to transport emitted species in plume form prior to their dilution at large scale. This method could be further improved to make the parameters used by the parameterization function of the local temperature, humidity and turbulence properties diagnosed by the large-scale model. Further extensions of the method can also be considered to account for multistep dilution regimes during the plume dissipation. Furthermore, the present parameterization can be adapted to other types of point-source NOx emissions that have to be

The Viking project. [summary

NASA Technical Reports Server (NTRS)

Soffen, G. A.

1977-01-01

The Viking project launched two unmanned spacecraft to Mars in 1975 for scientific exploration with special emphasis on the search for life. Each spacecraft consisted of an orbiter and a lander. The landing sites were finally selected after the spacecraft were in orbit. Thirteen investigations were performed: three mapping experiments from the orbiter, one atmospheric investigation during the lander entry phase, eight experiments on the surface of the planet, and one using the spacecraft radio and radar systems. The experiments on the surface dealt principally with biology, chemistry, geology, and meteorology. Seventy-eight scientists have participated in the 13 teams performing these experiments. This paper is a summary of the project and an introduction to the articles that follow.

Molecular Chemistry of Atmospheric Brown Carbon Inferred from a Nationwide Biomass Burning Event

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Peng; Bluvshtein, Nir; Rudich, Yinon

Lag Ba'Omer, a nationwide bonfire festival in Israel, was chosen as a case study to investigate the influence of a major biomass burning event on the light absorption properties of atmospheric brown carbon (BrC). The chemical composition and optical properties of BrC chromophores were investigated using a high performance liquid chromatography (HPLC) platform coupled to photo diode array (PDA) and high resolution mass spectrometry (HRMS) detectors. Substantial increase of BrC light absorption coefficient was observed during the night-long biomass burning event. Most chromophores observed during the event were attributed to nitroaromatic compounds, comprising 28 elemental formulas of at least 63more » structural isomers. The NAC, in combination, accounted for 50-80% of the total visible light absorption (> 400 nm) by solvent extractable BrC. The results highlight that NAC, particular nitrophenols, are important light absorption contributors of biomass burning organic aerosol (BBOA), suggesting that night time chemistry of ·NO 3 and N 2O 5 with particles may play a significant role in atmospheric transformations of BrC. Nitrophenols and related compounds were especially important chromophores of BBOA. The absorption spectra of the BrC chromophores are influenced by the extraction solvent and solution pH, implying that the aerosol acidity is an important factor controlling the light absorption properties of BrC.« less

Molecular Chemistry of Atmospheric Brown Carbon Inferred from a Nationwide Biomass Burning Event

DOE PAGES

Lin, Peng; Bluvshtein, Nir; Rudich, Yinon; ...

2017-08-26

Lag Ba'Omer, a nationwide bonfire festival in Israel, was chosen as a case study to investigate the influence of a major biomass burning event on the light absorption properties of atmospheric brown carbon (BrC). The chemical composition and optical properties of BrC chromophores were investigated using a high performance liquid chromatography (HPLC) platform coupled to photo diode array (PDA) and high resolution mass spectrometry (HRMS) detectors. Substantial increase of BrC light absorption coefficient was observed during the night-long biomass burning event. Most chromophores observed during the event were attributed to nitroaromatic compounds, comprising 28 elemental formulas of at least 63more » structural isomers. The NAC, in combination, accounted for 50-80% of the total visible light absorption (> 400 nm) by solvent extractable BrC. The results highlight that NAC, particular nitrophenols, are important light absorption contributors of biomass burning organic aerosol (BBOA), suggesting that night time chemistry of ·NO 3 and N 2O 5 with particles may play a significant role in atmospheric transformations of BrC. Nitrophenols and related compounds were especially important chromophores of BBOA. The absorption spectra of the BrC chromophores are influenced by the extraction solvent and solution pH, implying that the aerosol acidity is an important factor controlling the light absorption properties of BrC.« less

Containment Sodium Chemistry Models in MELCOR.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Louie, David; Humphries, Larry L.; Denman, Matthew R

To meet regulatory needs for sodium fast reactors’ future development, including licensing requirements, Sandia National Laboratories is modernizing MELCOR, a severe accident analysis computer code developed for the U.S. Nuclear Regulatory Commission (NRC). Specifically, Sandia is modernizing MELCOR to include the capability to model sodium reactors. However, Sandia’s modernization effort primarily focuses on the containment response aspects of the sodium reactor accidents. Sandia began modernizing MELCOR in 2013 to allow a sodium coolant, rather than water, for conventional light water reactors. In the past three years, Sandia has been implementing the sodium chemistry containment models in CONTAIN-LMR, a legacy NRCmore » code, into MELCOR. These chemistry models include spray fire, pool fire and atmosphere chemistry models. Only the first two chemistry models have been implemented though it is intended to implement all these models into MELCOR. A new package called “NAC” has been created to manage the sodium chemistry model more efficiently. In 2017 Sandia began validating the implemented models in MELCOR by simulating available experiments. The CONTAIN-LMR sodium models include sodium atmosphere chemistry and sodium-concrete interaction models. This paper presents sodium property models, the implemented models, implementation issues, and a path towards validation against existing experimental data.« less

Global volcanic emissions: budgets, plume chemistry and impacts

NASA Astrophysics Data System (ADS)

Mather, T. A.

2012-12-01

Over the past few decades our understanding of global volcanic degassing budgets, plume chemistry and the impacts of volcanic emissions on our atmosphere and environment has been revolutionized. Global volcanic emissions budgets are needed if we are to make effective use of regional and global atmospheric models in order to understand the consequences of volcanic degassing on global environmental evolution. Traditionally volcanic SO2 budgets have been the best constrained but recent efforts have seen improvements in the quantification of the budgets of other environmentally important chemical species such as CO2, the halogens (including Br and I) and trace metals (including measurements relevant to trace metal atmospheric lifetimes and bioavailability). Recent measurements of reactive trace gas species in volcanic plumes have offered intriguing hints at the chemistry occurring in the hot environment at volcanic vents and during electrical discharges in ash-rich volcanic plumes. These reactive trace species have important consequences for gas plume chemistry and impacts, for example, in terms of the global fixed nitrogen budget, volcanically induced ozone destruction and particle fluxes to the atmosphere. Volcanically initiated atmospheric chemistry was likely to have been particularly important before biological (and latterly anthropogenic) processes started to dominate many geochemical cycles, with important consequences in terms of the evolution of the nitrogen cycle and the role of particles in modulating the Earth's climate. There are still many challenges and open questions to be addressed in this fascinating area of science.

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.

Final Technical Report for earmark project "Atmospheric Science Program at the University of Louisville"

DOE Office of Scientific and Technical Information (OSTI.GOV)

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.

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

PubMed

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

2016-11-01

This work extends our previous experimental studies of the chemistry of Titan's atmosphere by atmospheric glow discharge. The Titan's atmosphere seems to be similarly to early Earth atmospheric composition. The exploration of Titan atmosphere was initiated by the exciting results of the Cassini-Huygens mission and obtained results increased the interest about prebiotic atmospheres. Present work is devoted to the role of CO 2 in the prebiotic atmosphere chemistry. Most of the laboratory studies of such atmosphere were focused on the chemistry of N 2  + CH 4 mixtures. The present work is devoted to the study of the oxygenated volatile species in prebiotic atmosphere, specifically CO 2 reactivity. CO 2 was introduced to the standard N 2  + CH 4 mixture at different mixing ratio up to 5 % CH 4 and 3 % CO 2 . The reaction products were characterized by FTIR spectroscopy. This work shows that CO 2 modifies the composition of the gas phase with the detection of oxygenated compounds: CO and others oxides. There is a strong influence of CO 2 on increasing concentration other products as cyanide (HCN) and ammonia (NH 3 ).

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…

Chemistry from Issues.

ERIC Educational Resources Information Center

Harding, Jan; Donaldson, Jim

1986-01-01

Describes the "Chemistry from Issues" project at Chelsea College. Provides the background information, rationale, and overall structure of a proposed course about the importance of chemistry to common culture. Outlines one module about the British steel industry that has been taught at King's College. (TW)

Distributions and Seasonal Variations of Tropospheric Ethene (C2H4) from Atmospheric Chemistry Experiment (ACE-FTS) Solar Occultation Spectra

NASA Technical Reports Server (NTRS)

Herbin, H.; Hurtmans, D.; Clarisse, L.; Turquety, S.; Clerbaux, C.; Rinsland, Curtis P.; Boone, C.; Bernath, P. F.; Coheur, P.-F.

2009-01-01

This work reports the first measurements of ethene (C2H4) distributions in the upper troposphere. These are obtained by retrieving vertical profiles from 5 to 20 km from infrared solar occultation spectra recorded in 2005 and 2006 by the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS). Background volume mixin^ ratios (vmrs) ranging from a few to about 50 pptv (10(exp -1) are measured at the different altitudes, while for certain occultations, vmrs as high as 200 pptv are observed. Zonal distributions and vertically resolved latitudinal distributions are derived for the two year period analyzed, highlighting spatial - including a North-South gradient - as well as seasonal variations. We show the latter to be more pronounced at the highest latitudes, presumably as a result of less active photochemistry during winter. The observation of C2H4 enhancements in remote Arctic regions at high latitudes is consistent with the occurrence of fast transport processes of gaseous pollution from the continents leading to Arctic haze. Citation: Herbin, H., D. Hurtmans, L. Clarisse, S. Turquety, C. Clerbaux, C. P. Rinsland, C. Boone, P. F. Bernath, and P.-F. Colieur (2009), Distributions and seasonal variations of tropospheric ethene (C2H4) from Atmospheric Chemistry Experiment (ACE-FTS) solar occultation spectra,

Refining multi-model projections of temperature extremes by evaluation against land-atmosphere coupling diagnostics

NASA Astrophysics Data System (ADS)

Sippel, Sebastian; Zscheischler, Jakob; Mahecha, Miguel D.; Orth, Rene; Reichstein, Markus; Vogel, Martha; Seneviratne, Sonia I.

2017-05-01

The Earth's land surface and the atmosphere are strongly interlinked through the exchange of energy and matter. This coupled behaviour causes various land-atmosphere feedbacks, and an insufficient understanding of these feedbacks contributes to uncertain global climate model projections. For example, a crucial role of the land surface in exacerbating summer heat waves in midlatitude regions has been identified empirically for high-impact heat waves, but individual climate models differ widely in their respective representation of land-atmosphere coupling. Here, we compile an ensemble of 54 combinations of observations-based temperature (T) and evapotranspiration (ET) benchmarking datasets and investigate coincidences of T anomalies with ET anomalies as a proxy for land-atmosphere interactions during periods of anomalously warm temperatures. First, we demonstrate that a large fraction of state-of-the-art climate models from the Coupled Model Intercomparison Project (CMIP5) archive produces systematically too frequent coincidences of high T anomalies with negative ET anomalies in midlatitude regions during the warm season and in several tropical regions year-round. These coincidences (high T, low ET) are closely related to the representation of temperature variability and extremes across the multi-model ensemble. Second, we derive a land-coupling constraint based on the spread of the T-ET datasets and consequently retain only a subset of CMIP5 models that produce a land-coupling behaviour that is compatible with these benchmark estimates. The constrained multi-model simulations exhibit more realistic temperature extremes of reduced magnitude in present climate in regions where models show substantial spread in T-ET coupling, i.e. biases in the model ensemble are consistently reduced. Also the multi-model simulations for the coming decades display decreased absolute temperature extremes in the constrained ensemble. On the other hand, the differences between projected

A model of CO-CH4 global transport/chemistry. I - Chemistry model

NASA Technical Reports Server (NTRS)

Peters, L. K.; Kitada, T.

1980-01-01

A simplified chemistry model was developed to incorporate the CO-CH4 chemistry into the global transport model of these compounds. CO is important because of its effects on atmospheric chemistry and is partly responsible for controlling the hydroxyl radical (OH) concentration in the troposphere. The model includes the photodissociation rate coefficients expressed as functions of solar zenith angle and altitude, and it was applied to determine the sensitivity of the OH concentration to trace gaseous species, such as NOx, O3, and H2O. Also, the concentrations and diurnal variations of OH and HO2, and the contribution of individual reactions to OH generation and consumption were calculated.

Development of a chlorine chemistry module for the Master Chemical Mechanism

NASA Astrophysics Data System (ADS)

Xue, L. K.; Saunders, S. M.; Wang, T.; Gao, R.; Wang, X. F.; Zhang, Q. Z.; Wang, W. X.

2015-06-01

The chlorine atom (Cl·) has a high potential to perturb atmospheric photochemistry by oxidizing volatile organic compounds (VOCs), but the exact role it plays in the polluted troposphere remains unclear. The Master Chemical Mechanism (MCM) is a near explicit mechanism that has been widely applied in the atmospheric chemistry research. While it addresses comprehensively the chemistry initiated by the OH, O3 and NO3 radicals, its representation of the Cl· chemistry is incomplete as it only considers the reactions for alkanes. In this paper, we develop a more comprehensive Cl· chemistry module that can be directly incorporated within the MCM framework. A suite of 199 chemical reactions describes the Cl·-initiated degradation of alkenes, aromatics, aldehydes, ketones, alcohols, and some organic acids and nitrates, along with the inorganic chemistry involving Cl· and its precursors. To demonstrate the potential influence of the new chemistry module, it was incorporated into a MCM box model to evaluate the impacts of nitryl chloride (ClNO2), a product of nocturnal halogen activation by nitrogen oxides (NOx), on the following-day's atmospheric photochemistry. With constraints of recent observations collected at a coastal site in Hong Kong, southern China, the modeling analyses suggest that the Cl· produced from ClNO2 photolysis may substantially enhance the atmospheric oxidative capacity, VOC oxidation, and O3 formation, particularly in the early morning period. The results demonstrate the critical need for photochemical models to include more fully chlorine chemistry in order to better understand the atmospheric photochemistry in polluted environments subject to intense emissions of NOx, VOCs and chlorine-containing constituents.

Development of a chlorine chemistry module for the Master Chemical Mechanism

NASA Astrophysics Data System (ADS)

Xue, L. K.; Saunders, S. M.; Wang, T.; Gao, R.; Wang, X. F.; Zhang, Q. Z.; Wang, W. X.

2015-10-01

The chlorine atom (Cl·) has a high potential to perturb atmospheric photochemistry by oxidizing volatile organic compounds (VOCs), but the exact role it plays in the polluted troposphere remains unclear. The Master Chemical Mechanism (MCM) is a near-explicit mechanism that has been widely applied in the atmospheric chemistry research. While it addresses comprehensively the chemistry initiated by the OH, O3 and NO3 radicals, its representation of the Cl· chemistry is incomplete as it only considers the reactions for alkanes. In this paper, we develop a more comprehensive Cl· chemistry module that can be directly incorporated within the MCM framework. A suite of 205 chemical reactions describes the Cl·-initiated degradation of alkenes, aromatics, alkynes, aldehydes, ketones, alcohols, and some organic acids and nitrates, along with the inorganic chemistry involving Cl· and its precursors. To demonstrate the potential influence of the new chemistry module, it was incorporated into a MCM box model to evaluate the impacts of nitryl chloride (ClNO2), a product of nocturnal halogen activation by nitrogen oxides (NOX), on the following day's atmospheric photochemistry. With constraints of recent observations collected at a coastal site in Hong Kong, southern China, the modeling analyses suggest that the Cl· produced from ClNO2 photolysis may substantially enhance the atmospheric oxidative capacity, VOC oxidation and O3 formation, particularly in the early morning period. The results demonstrate the critical need for photochemical models to include more detailed chlorine chemistry in order to better understand the atmospheric photochemistry in polluted environments subject to intense emissions of NOX, VOCs and chlorine-containing constituents.

Global Analysis of Climate Change Projection Effects on Atmospheric Rivers

NASA Astrophysics Data System (ADS)

Espinoza, Vicky; Waliser, Duane E.; Guan, Bin; Lavers, David A.; Ralph, F. Martin

2018-05-01

A uniform, global approach is used to quantify how atmospheric rivers (ARs) change between Coupled Model Intercomparison Project Phase 5 historical simulations and future projections under the Representative Concentration Pathway (RCP) 4.5 and RCP8.5 warming scenarios. The projections indicate that while there will be 10% fewer ARs in the future, the ARs will be 25% longer, 25% wider, and exhibit stronger integrated water vapor transports (IVTs) under RCP8.5. These changes result in pronounced increases in the frequency (IVT strength) of AR conditions under RCP8.5: 50% (25%) globally, 50% (20%) in the northern midlatitudes, and 60% (20%) in the southern midlatitudes. The models exhibit systematic low biases across the midlatitudes in replicating historical AR frequency ( 10%), zonal IVT ( 15%), and meridional IVT ( 25%), with sizable intermodel differences. A more detailed examination of six regions strongly impacted by ARs suggests that the western United States, northwestern Europe, and southwestern South America exhibit considerable intermodel differences in projected changes in ARs.

Aerosol Variations in Boundary Atmospheres: Review and Prospect

NASA Astrophysics Data System (ADS)

Chen, Bin; Shi, Guangyu

Atmospheric aerosols play important roles in climate and atmospheric chemistry: They scatter sunlight, provide condensation nuclei for cloud droplets, and participate in heterogeneous chemical reactions. To enable better understanding of the vertical physical, chemical and optical feathers of the aerosols in East Asia, using some atmospheric and aerosol measurement instruments on board a kind of tethered-balloon system, a series of measurements were operated in some typical areas of East Asia, including Dunhuang, which is located in the source origin district of Asian dust and Beijing, which is the representative of large inland city during the years of 2002-2011. Mineral compositions carried by the airborne particles were analyzed as well as the microbial components, meanwhile the Lidar data were compared to the direct measurements in order to get the correlation between the optical properties of the particles and their physical and chemical variations in the boundary atmosphere. Moreover, the simultaneous observations over the districts of China, Japan and Korea, and even Pakistan supported by an international cooperative project are highly expected, in order to know the changes of the chemical, physical and even optical and radiation properties of the atmospheric aerosols during their long-range transport.

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

Building "My First NMRviewer": A Project Incorporating Coding and Programming Tasks in the Undergraduate Chemistry Curricula

ERIC Educational Resources Information Center

Arrabal-Campos, Francisco M.; Cortés-Villena, Alejandro; Fernández, Ignacio

2017-01-01

This paper presents a programming project named NMRviewer that allows students to visualize transformed and processed 1 H NMR data in an accessible, interactive format while allowing instructors to incorporate programming content into the chemistry curricula. Using the MATLAB graphical user interface development environment (GUIDE), students can…

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.

Chemistry in protoplanetary disks

NASA Astrophysics Data System (ADS)

Semenov, D. A.

2012-01-01

In this lecture I discuss recent progress in the understanding of the chemical evolution of protoplanetary disks that resemble our Solar system during the first ten million years. At the verge of planet formation, strong variations of temperature, density, and radiation intensities in these disks lead to a layered chemical structure. In hot, dilute and heavily irradiated atmosphere only simple radicals, atoms, and atomic ions can survive, formed and destroyed by gas-phase processes. Beneath the atmosphere a partly UV-shielded, warm molecular layer is located, where high-energy radiation drives rich chemistry, both in the gas phase and on dust surfaces. In a cold, dense, dark disk midplane many molecules are frozen out, forming thick icy mantles where surface chemistry is active and where complex (organic) species are synthesized.

Global Atmospheric Aerosol Modeling

NASA Technical Reports Server (NTRS)

Hendricks, Johannes; Aquila, Valentina; Righi, Mattia

2012-01-01

Global aerosol models are used to study the distribution and properties of atmospheric aerosol particles as well as their effects on clouds, atmospheric chemistry, radiation, and climate. The present article provides an overview of the basic concepts of global atmospheric aerosol modeling and shows some examples from a global aerosol simulation. Particular emphasis is placed on the simulation of aerosol particles and their effects within global climate models.

Atmospheric measurements using the LAMP lidar during the LADIMAS campaign

NASA Technical Reports Server (NTRS)

Philbrick, C. R.; Lysak, D. B.; Stevens, T. D.; Haris, P. A. T.; Rau, Y.-C.

1992-01-01

The results of the LAtitudinal DIstribution of Middle Atmosphere Structure (LADIMAS) experiment have provided a unique data set to improve our understanding of the middle atmosphere. The project included shipboard and rocket range coordinated measurements between 70 deg N to 65 deg S to study the structure, dynamics, and chemistry of the atmosphere. Results on important dynamical processes, such as gravity waves, tidal components, as well as the formation of the layers of meteoric ion and neutral species, were obtained with lidar, digisonde, microwave radiometer, and spectrometers. The cooperative study of the atmosphere was undertaken by researchers from several laboratories, including Penn State University (PSU), University Bonn, University Wuppertal, Lowell University, and others. Several of the parameters studied have never been measured before over such a wide range of latitudes. Instruments were assembled aboard the German research vessel RV POLARSTERN while this vessel was sailing from the Arctic to the Antarctic seas between 8 Oct. 1991 - 2 Jan. 1992. This paper presents an introduction to the data gathered by the PSU investigation with the Lidar Atmospheric Measurements Program (LAMP) lidar.

FORest canopy atmosphere transfer (FORCAsT) 1.0: a 1-D model of biosphere-atmosphere chemical exchange

NASA Astrophysics Data System (ADS)

Ashworth, K.; Chung, S. H.; Griffin, R. J.; Chen, J.; Forkel, R.; Bryan, A. M.; Steiner, A. L.

2015-07-01

Biosphere-atmosphere interactions play a critical role in governing atmospheric composition, mediating the concentration of key species such as ozone and aerosol, thereby influencing air quality and climate. The exchange of reactive trace gases and their oxidation products (both gas and particle phase) is of particular importance in this process. The FORCAsT (FORest Canopy AtmoSphere Transfer) one-dimensional model is developed to study the emission, deposition, chemistry and transport of volatile organic compounds (VOCs) and their oxidation products in the atmosphere within and above the forest canopy. We include an equilibrium partitioning scheme, making FORCAsT one of the few canopy models currently capable of simulating the formation of secondary organic aerosols (SOA) from VOC oxidation in a forest environment. We evaluate the capability of FORCAsT to reproduce observed concentrations of key gas-phase species and report modeled SOA concentrations within and above a mixed forest at the University of Michigan Biological Station (UMBS) during the Community Atmosphere-Biosphere Interactions Experiment (CABINEX) field campaign in summer 2009. We examine the impact of two different gas-phase chemical mechanisms on modelled concentrations of short-lived primary emissions, such as isoprene and monoterpenes, and their oxidation products. While the two chemistry schemes perform similarly under high-NOx conditions, they diverge at the low levels of NOx at UMBS. We identify peroxy radical and alkyl nitrate chemistry as the key causes of the differences, highlighting the importance of this chemistry in understanding the fate of biogenic VOCs (bVOCs) for both the modelling and measurement communities.

FORest Canopy Atmosphere Transfer (FORCAsT) 1.0: a 1-D model of biosphere-atmosphere chemical exchange

NASA Astrophysics Data System (ADS)

Ashworth, K.; Chung, S. H.; Griffin, R. J.; Chen, J.; Forkel, R.; Bryan, A. M.; Steiner, A. L.

2015-11-01

Biosphere-atmosphere interactions play a critical role in governing atmospheric composition, mediating the concentrations of key species such as ozone and aerosol, thereby influencing air quality and climate. The exchange of reactive trace gases and their oxidation products (both gas and particle phase) is of particular importance in this process. The FORCAsT (FORest Canopy Atmosphere Transfer) 1-D model is developed to study the emission, deposition, chemistry and transport of volatile organic compounds (VOCs) and their oxidation products in the atmosphere within and above the forest canopy. We include an equilibrium partitioning scheme, making FORCAsT one of the few canopy models currently capable of simulating the formation of secondary organic aerosols (SOAs) from VOC oxidation in a forest environment. We evaluate the capability of FORCAsT to reproduce observed concentrations of key gas-phase species and report modeled SOA concentrations within and above a mixed forest at the University of Michigan Biological Station (UMBS) during the Community Atmosphere-Biosphere Interactions Experiment (CABINEX) field campaign in the summer of 2009. We examine the impact of two different gas-phase chemical mechanisms on modelled concentrations of short-lived primary emissions, such as isoprene and monoterpenes, and their oxidation products. While the two chemistry schemes perform similarly under high-NOx conditions, they diverge at the low levels of NOx at UMBS. We identify peroxy radical and alkyl nitrate chemistry as the key causes of the differences, highlighting the importance of this chemistry in understanding the fate of biogenic VOCs (bVOCs) for both the modelling and measurement communities.

Epoxying Isoprene Chemistry

EPA Science Inventory

It seems that every few months we read about another missing aspect of atmospheric chemistry: missing products, missing reactivity, missing sources, missing understanding. Thus, it is with some relief that we read in this issue the paper of Paulot et al. The paper provides more...

Observations of biogenic isoprene emissions and atmospheric chemistry components at the Savé super site in Benin, West Africa, during the DACCIWA field campaign.

NASA Astrophysics Data System (ADS)

Jambert, Corinne; Pacifico, Federica; Delon, Claire; Lohou, Fabienne; Reinares Martinez, Irene; Brilouet, Pierre-Etienne; Derrien, Solene; Dione, Cheikh; Brosse, Fabien; Gabella, Omar; Pedruzzo Bagazgoitia, Xavier; Durand, Pierre

2017-04-01

Tropospheric oxidation of VOCs (Volatile Organic Compounds), including isoprene, in the presence of NOx and sunlight leads to the formation of O3 and Secondary Organic Aerosols (SOA). Changes in NO or VOCs sources will consequently modify their atmospheric concentrations and thus, the rate of O3 production and SOA formation. NOx have also an impact on the abundance of the hydroxyl radical (OH) which determines the lifetime of some pollutants and greenhouse gases. Anthropogenic emissions of pollutants from mega cities located on the Guinean coast in South West Africa are likely to increase in the next decades due to a strong anthropogenic pressure and to land use changes at the regional or continental scale. The consequences on regional air quality and on pollutant deposition onto surfaces may have some harmful effects on human and ecosystem health. Furthermore, the regional climate and water cycle are affected by changes in atmospheric chemistry. When transported northward on the African continent, polluted air masses meet biogenic emissions from rural areas which contributes to increase ozone and SOA production, in high temperature and solar radiation conditions, highly favourable to enhanced photochemistry. During the Dynamics-aerosol-chemistry-cloud interactions in West Africa (DACCIWA) field campaign, we measured the atmospheric chemical composition and the exchanges of trace components in a hinterland area of Benin, at the Savé super-site (8°02'03" N, 2°29'11″ E). The observations, monitored in June and July 2016, in a rural mixed agricultural area, include near surface concentrations of ozone (O3), carbon monoxide (CO), nitrogen oxides (NOx) and isoprene, isoprene fluxes and meteorological parameters. We observed hourly average concentrations of O3 up to 50 ppb, low NOx concentrations (ca. 1 ppb and CO concentrations between 75 and 300 ppb. An 8 m tower was equipped with a Fast Isoprene Sensor and sonic anemometer to measure isoprene concentrations and

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.

Sulfur mass loading of the atmosphere from volcanic eruptions: Calibration of the ice core record on basis of sulfate aerosol deposition in polar regions from the 1982 El Chichon eruption

NASA Technical Reports Server (NTRS)

Sigurdsson, Haraldur; Laj, Paolo

1990-01-01

Major volcanic eruptions disperse large quantities of sulfur compound throughout the Earth's atmosphere. The sulfuric acid aerosols resulting from such eruptions are scavenged by snow within the polar regions and appear in polar ice cores as elevated acidity layers. Glacio-chemical studies of ice cores can, thus, provide a record of past volcanism, as well as the means for understanding the fate of volcanic sulfur in the atmosphere. The primary objectives of this project are to study the chemistry and physical properties of volcanic fallout in a Greenland Ice Core in order to evaluate the impact of the volcanic gases on the atmospheric chemistry and the total atmospheric mass of volcanic aerosols emitted by major volcanic eruptions. We propose to compare the ice core record to other atmospheric records performed during the last 10 years to investigate transport and deposition of volcanic materials.

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.

Two High-Resolution, Quantitative, Infrared Spectral Libraries for Atmospheric Chemistry

NASA Astrophysics Data System (ADS)

Johnson, T. J.; Sharpe, S. W.; Sams, R. L.; Chu, P. M.

2001-12-01

The Pacific Northwest National Laboratory (PNNL) and the National Institute of Standards and Technology (NIST) are independently creating quantitative, 0.10 cm-1 resolution, infrared spectral libraries of vapor phase compounds. Both libraries contain many species of use to the gas-phase spectroscopist, including for atmospheric chemistry. The NIST library will consist of approximately 100 vapor phase spectra primarily associated with volatile hazardous air pollutants (HAPs) and suspected greenhouse gases, whereas the PNNL library will consist of approximately 400 vapor phase spectra associated with DOE's remediation mission. Data are being recorded from 600 to 6500 cm-1 to cover not only the classical fingerprint region, but much of the near-infrared as well. The wavelength axis is calibrated against published standards. To prepare the samples, the two laboratories use significantly different sample preparation and handling techniques: NIST uses gravimetric dilution and a continuous flowing sample while PNNL uses partial pressure dilution and a static sample. The data are validated against one another and agreement on the ordinate axis is generally found to be within the statistical uncertainties (2σ ) of the Beer's law fit and less than 3 % of the total integrated band areas for the 4 chemicals used in this comparison. The nature of the two databases and the rigorous nature used to acquire the data will be briefly discussed.

ECHMERIT: A new on-line global mercury-chemistry model

NASA Astrophysics Data System (ADS)

Jung, G.; Hedgecock, I. M.; Pirrone, N.

2009-04-01

Mercury is a volatile metal, that is of concern because when deposited and transformed to methylmercury accumulates within the food-web. Due to the long lifetime of elemental mercury, which is the dominant fraction of mercury species in the atmosphere, mercury is prone to long-range transport and therefore distributed over the globe, transported and hence deposited even in regions far from anthropogenic emission sources. Mercury is released to the atmosphere from a variety of natural and anthropogenic sources, in elementary and oxidised forms, and as particulate mercury. It is then transported, but also transformed chemically in the gaseous phase, as well as in aqueous phase within cloud and rain droplets. Mercury (particularly its oxidised forms) is removed from the atmosphere though wet and dry deposition processes, a large fraction of deposited mercury is, after chemical or biological reduction, re-emitted to the atmosphere as elementary mercury. To investigate mercury chemistry and transport processes on the global scale, the new, global model ECHMERIT has been developed. ECHMERIT simulates meteorology, transport, deposition, photolysis and chemistry on-line. The general circulation model on which ECHMERIT is based is ECHAM5. Sophisticated chemical modules have been implemented, including gas phase chemistry based on the CBM-Z chemistry mechanism, as well as aqueous phase chemistry, both of which have been adapted to include Hg chemistry and Hg species gas-droplet mass transfer. ECHMERIT uses the fast-J photolysis routine. State-of-the-art procedures simulating wet and dry deposition and emissions were adapted and included in the model as well. An overview of the model structure, development, validation and sensitivity studies is presented.

Laboratory for Atmospheres 2008 Technical Highlights

NASA Technical Reports Server (NTRS)

Cote, Charles E.

2009-01-01

The 2008 Technical Highlights describes the efforts of all members of the Laboratory for Atmospheres. Their dedication to advancing Earth Science through conducting research, developing and running models, designing instruments, managing projects, running field campaigns, and numerous other activities, is highlighted in this report. The Laboratory for Atmospheres (Code 613) is part of the Earth Sciences Division (Code 610), formerly the Earth Sun Exploration Division, under the Sciences and Exploration Directorate (Code 600) based at NASA s Goddard Space Flight Center in Greenbelt, Maryland. In line with NASA s Exploration Initiative, the Laboratory executes a comprehensive research and technology development program dedicated to advancing knowledge and understanding of the atmospheres of Earth and other planets. The research program is aimed at understanding the influence of solar variability on the Earth s climate; predicting the weather and climate of Earth; understanding the structure, dynamics, and radiative properties of precipitation, clouds, and aerosols; understanding atmospheric chemistry, especially the role of natural and anthropogenic trace species on the ozone balance in the stratosphere and the troposphere; and advancing our understanding of physical properties of Earth s atmosphere. The research program identifies problems and requirements for atmospheric observations via satellite missions. Laboratory scientists conceive, design, develop, and implement ultraviolet, infrared, optical, radar, laser, and lidar technology for remote sensing of the atmosphere. Laboratory members conduct field measurements for satellite data calibration and validation, and carry out numerous modeling activities. These modeling activities include climate model simulations, modeling the chemistry and transport of trace species on regional-to-global scales, cloud-resolving models, and development of next-generation Earth system models. Interdisciplinary research is carried

Dimethylsulfide chemistry: annual, seasonal, and spatial impacts on SO_4^(2-)

EPA Science Inventory

We incorporated oceanic emissions and atmospheric chemistry of dimethylsulfide (DMS) into the hemispheric Community Multiscale Air Quality model and performed annual model simulations without and with DMS chemistry. The model without DMS chemistry predicts higher concentrations o...

Simulation of a dust episode over Eastern Mediterranean using a high-resolution atmospheric chemistry general circulation model

NASA Astrophysics Data System (ADS)

Abdel Kader, Mohamed; Zittis, Georgios; Astitha, Marina; Lelieveld, Jos; Tymvios, Fillipos

2013-04-01

An extended episode of low visibility took place over the Eastern Mediterranean in late September 2011, caused by a strong increase in dust concentrations, analyzed from observations of PM10 (Particulate Matter with <10μm in diameter). A high-resolution version of the atmospheric chemistry general circulation model EMAC (ECHAM5/Messy2.41 Atmospheric Chemistry) was used to simulate the emissions, transport and deposition of airborne desert dust. The model configuration involves the spectral resolution of T255 (0.5°, ~50Km) and 31 vertical levels in the troposphere and lower stratosphere. The model was nudged towards ERA40 reanalysis data to represent the actual meteorological conditions. The dust emissions were calculated online at each model time step and the aerosol microphysics using the GMXe submodel (Global Modal-aerosol eXtension). The model includes a sulphur chemistry mechanism to simulate the transformation of the dust particles from the insoluble (at emission) to soluble modes, which promotes dust removal by precipitation. The model successfully reproduces the dust distribution according to observations by the MODIS satellite instruments and ground-based AERONET stations. The PM10 concentration is also compared with in-situ measurements over Cyprus, resulting in good agreement. The model results show two subsequent dust events originating from the Negev and Sahara deserts. The first dust event resulted from the transport of dust from the Sahara on the 21st of September and lasted only briefly (hours) as the dust particles were efficiently removed by precipitation simulated by the model and observed by the TRMM (Tropical Rainfall Measuring Mission) satellites. The second event resulted from dust transport from the Negev desert to the Eastern Mediterranean during the period 26th - 30th September with a peak concentration at 2500m elevation. This event lasted for four days and diminished due to dry deposition. The observed reduced visibility over Cyprus

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…

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.

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.…

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.

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.

Medicinal Chemistry Projects Requiring Imaginative Structure-Based Drug Design Methods.

PubMed

Moitessier, Nicolas; Pottel, Joshua; Therrien, Eric; Englebienne, Pablo; Liu, Zhaomin; Tomberg, Anna; Corbeil, Christopher R

2016-09-20

Computational methods for docking small molecules to proteins are prominent in drug discovery. There are hundreds, if not thousands, of documented examples-and several pertinent cases within our research program. Fifteen years ago, our first docking-guided drug design project yielded nanomolar metalloproteinase inhibitors and illustrated the potential of structure-based drug design. Subsequent applications of docking programs to the design of integrin antagonists, BACE-1 inhibitors, and aminoglycosides binding to bacterial RNA demonstrated that available docking programs needed significant improvement. At that time, docking programs primarily considered flexible ligands and rigid proteins. We demonstrated that accounting for protein flexibility, employing displaceable water molecules, and using ligand-based pharmacophores improved the docking accuracy of existing methods-enabling the design of bioactive molecules. The success prompted the development of our own program, Fitted, implementing all of these aspects. The primary motivation has always been to respond to the needs of drug design studies; the majority of the concepts behind the evolution of Fitted are rooted in medicinal chemistry projects and collaborations. Several examples follow: (1) Searching for HDAC inhibitors led us to develop methods considering drug-zinc coordination and its effect on the pKa of surrounding residues. (2) Targeting covalent prolyl oligopeptidase (POP) inhibitors prompted an update to Fitted to identify reactive groups and form bonds with a given residue (e.g., a catalytic residue) when the geometry allows it. Fitted-the first fully automated covalent docking program-was successfully applied to the discovery of four new classes of covalent POP inhibitors. As a result, efficient stereoselective syntheses of a few screening hits were prioritized rather than synthesizing large chemical libraries-yielding nanomolar inhibitors. (3) In order to study the metabolism of POP inhibitors by

FAST TRACK COMMUNICATION: Contrasting characteristics of sub-microsecond pulsed atmospheric air and atmospheric pressure helium-oxygen glow discharges

NASA Astrophysics Data System (ADS)

Walsh, J. L.; Liu, D. X.; Iza, F.; Rong, M. Z.; Kong, M. G.

2010-01-01

Glow discharges in air are often considered to be the ultimate low-temperature atmospheric pressure plasmas for numerous chamber-free applications. This is due to the ubiquitous presence of air and the perceived abundance of reactive oxygen and nitrogen species in air plasmas. In this paper, sub-microsecond pulsed atmospheric air plasmas are shown to produce a low concentration of excited oxygen atoms but an abundance of excited nitrogen species, UV photons and ozone molecules. This contrasts sharply with the efficient production of excited oxygen atoms in comparable helium-oxygen discharges. Relevant reaction chemistry analysed with a global model suggests that collisional excitation of O2 by helium metastables is significantly more efficient than electron dissociative excitation of O2, electron excitation of O and ion-ion recombination. These results suggest different practical uses of the two oxygen-containing atmospheric discharges, with air plasmas being well suited for nitrogen and UV based chemistry and He-O2 plasmas for excited atomic oxygen based chemistry.

Atmospheric River Tracking Method Intercomparison Project (ARTMIP): Science Goals and Preliminary Analysis

NASA Astrophysics Data System (ADS)

Shields, C. A.; Rutz, J. J.; Wehner, M. F.; Ralph, F. M.; Leung, L. R.

2017-12-01

The Atmospheric River Tracking Method Intercomparison Project (ARTMIP) is a community effort whose purpose is to quantify uncertainties in atmospheric river (AR) research solely due to different identification and tracking techniques. Atmospheric rivers transport significant amounts of moisture in long, narrow filamentary bands, typically travelling from the subtropics to the mid-latitudes. They are an important source of regional precipitation impacting local hydroclimate, and in extreme cases, cause severe flooding and infrastructure damage in local communities. Our understanding of ARs, from forecast skill to future climate projections, all hinge on how we define ARs. By comparing a diverse set of detection algorithms, the uncertainty in our definition of ARs, (including statistics and climatology), and the implications of those uncertainties, can be analyzed and quantified. ARTMIP is divided into two broad phases that aim to answer science questions impacted by choice of detection algorithm. How robust are AR metrics such as climatology, storm duration, and relationship to extreme precipitation? How are the AR metrics in future climate projections impacted by choice of algorithm? Some algorithms rely on threshold values for water vapor. In a warmer world, the background state, by definition, is moister due to the Clausius-Clapeyron relationship, and could potentially skew results. Can uncertainty bounds be accurately placed on each metric? Tier 1 participants will apply their algorithms to a high resolution common dataset (MERRA2) and provide the greater group AR metrics (frequency, location, duration, etc). Tier 2 research will encompass sensitivity studies regarding resolution, reanalysis choice, and future climate change scenarios. ARTMIP is currently in the Tier 1 Phase and will begin Tier 2 in 2018. Preliminary metrics and analysis from Tier 1 will be presented.

Ozone, Climate, and Global Atmospheric Change

NASA Technical Reports Server (NTRS)

Levine, Joel S.

1992-01-01

The delicate balance of the gases that make up our atmosphere allows life to exist on Earth. Ozone depletion and global warming are related to changes in the concentrations of these gases. To solve global atmospheric problems, we need to understand the composition and chemistry of the Earth's atmosphere and the impact of human activities on them.

A three-dimensional model of the atmospheric chemistry of E and Z-CF3CH=CHCl (HCFO-1233(zd) (E/Z))

NASA Astrophysics Data System (ADS)

Sulbaek Andersen, Mads P.; Schmidt, Johan A.; Volkova, Aleksandra; Wuebbles, Donald J.

2018-04-01

Using a 3-dimensional global atmospheric chemistry and transport model we investigated the atmospheric degradation of HCFO-1233zd(E), E-CF3CH=CHCl, a commercially important, new hydrofluorocarbon replacement compound. Atmospheric degradation of E-CF3CH=CHCl is initiated by reaction with OH radicals, which leads to several chemical oxidation products. Dissemination of these oxidation products to the environment is of concern due to the possible formation of trifluoroacetic acid (TFA) as a degradation product. The model indicates that the average global yield of TFA from atmospheric processing of E-CF3CH=CHCl is approximately 2%. The annually averaged atmospheric lifetime of E-CF3CH=CHCl was found to be approximately 36 days (12 days for Z-CF3CH=CHCl). As E-CF3CH=CHCl is short lived, by far the majority of its Cl atoms will be released and deposited in the lower atmosphere, and the impact on stratospheric ozone is insignificant. An Ozone Depletion Potential of 0.00030 was determined. The Photochemical Ozone Creation Potential was evaluated and a value of 3.6 determined. Finally, we derive a Global Warming Potential for E-CF3CH=CHCl for a 100 year time horizon of <5. For comparison, data for the stereoismeric analogue, Z-CF3CH=CHCl, was also obtained from the model.

Exoplanetary Atmospheres—Chemistry, Formation Conditions, and Habitability

PubMed Central

Agúndez, Marcelino; Moses, Julianne I; Hu, Yongyun

2016-01-01

Characterizing the atmospheres of extrasolar planets is the new frontier in exoplanetary science. The last two decades of exoplanet discoveries have revealed that exoplanets are very common and extremely diverse in their orbital and bulk properties. We now enter a new era as we begin to investigate the chemical diversity of exoplanets, their atmospheric and interior processes, and their formation conditions. Recent developments in the field have led to unprecedented advancements in our understanding of atmospheric chemistry of exoplanets and the implications for their formation conditions. We review these developments in the present work. We review in detail the theory of atmospheric chemistry in all classes of exoplanets discovered to date, from highly irradiated gas giants, ice giants, and super-Earths, to directly imaged giant planets at large orbital separations. We then review the observational detections of chemical species in exoplanetary atmospheres of these various types using different methods, including transit spectroscopy, Doppler spectroscopy, and direct imaging. In addition to chemical detections, we discuss the advances in determining chemical abundances in these atmospheres and how such abundances are being used to constrain exoplanetary formation conditions and migration mechanisms. Finally, we review recent theoretical work on the atmospheres of habitable exoplanets, followed by a discussion of future outlook of the field. PMID:28057962

Exoplanetary Atmospheres—Chemistry, Formation Conditions, and Habitability

NASA Astrophysics Data System (ADS)

Madhusudhan, Nikku; Agúndez, Marcelino; Moses, Julianne I.; Hu, Yongyun

2016-12-01

Characterizing the atmospheres of extrasolar planets is the new frontier in exoplanetary science. The last two decades of exoplanet discoveries have revealed that exoplanets are very common and extremely diverse in their orbital and bulk properties. We now enter a new era as we begin to investigate the chemical diversity of exoplanets, their atmospheric and interior processes, and their formation conditions. Recent developments in the field have led to unprecedented advancements in our understanding of atmospheric chemistry of exoplanets and the implications for their formation conditions. We review these developments in the present work. We review in detail the theory of atmospheric chemistry in all classes of exoplanets discovered to date, from highly irradiated gas giants, ice giants, and super-Earths, to directly imaged giant planets at large orbital separations. We then review the observational detections of chemical species in exoplanetary atmospheres of these various types using different methods, including transit spectroscopy, Doppler spectroscopy, and direct imaging. In addition to chemical detections, we discuss the advances in determining chemical abundances in these atmospheres and how such abundances are being used to constrain exoplanetary formation conditions and migration mechanisms. Finally, we review recent theoretical work on the atmospheres of habitable exoplanets, followed by a discussion of future outlook of the field.

Space Shuttle Projects

NASA Image and Video Library

1992-09-12

This STS-48 onboard photo is of the Upper Atmosphere Research Satellite (UARS) in the grasp of the RMS (Remote Manipulator System) during deployment, September 1991. UARS gathers data related to the chemistry, dynamics, and energy of the ozone layer. UARS data is used to study energy input, stratospheric photo chemistry, and upper atmospheric circulation. UARS helps us understand and predict how the nitrogen and chlorine cycles, and the nitrous oxides and halo carbons which maintain them, relate to the ozone balance. It also observes diurnal variations in short-lived stratospheric chemical species important to ozone destruction. Data from UARS enables scientists to study ozone depletion in the upper atmosphere.

Space Shuttle Projects

NASA Image and Video Library

1991-09-12

This STS-48 onboard photo is of the Upper Atmosphere Research Satellite (UARS) in the grasp of the RMS (Remote Manipulator System) during deployment, September 1991. UARS gathers data related to the chemistry, dynamics, and energy of the ozone layer. UARS data is used to study energy input, stratospheric photo chemistry, and upper atmospheric circulation. UARS helps us understand and predict how the nitrogen and chlorine cycles, and the nitrous oxides and halo carbons which maintain them, relate to the ozone balance. It also observes diurnal variations in short-lived stratospheric chemical species important to ozone destruction. Data from UARS enables scientists to study ozone depletion in the upper atmosphere.

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.

Global Ozone and Reactive Nitrogen : Composition, Chemistry and Sources

NASA Technical Reports Server (NTRS)

Sing, Hanwant B.; Bradshaw, J.; Davis, D.; Gregory, G.; Talbot, R.

1994-01-01

Ozone plays a central role in the chemistry of the atmosphere both as an ultraviolet shield and as a source of hydroxyl radicals (OH), a potent initiator of atmospheric chemistry. There is evidence to suggest that the ozone abundance in the troposphere (0-10 km) has doubled since the industrial revolution and continues to increase to date. The principle reason for this increase is thought to be the increasing emissions of nitrogen oxides (NO(x)) from anthropogenic activities. Although NO(x) is highly reactive and its products such as HN03 are easily removed by deposition, it now appears that its chemistry is quite complex and it can be transported over long distances via its conversion to a variety of nitrates and penetrates. The sources of atmospheric NO(x) include free tropospheric sources such as lightning and subsonic aircraft, as well as surface emissions which are transported to the free troposphere via convective processes. Recent experimental and theoretical studies have tried to unravel the chemistry of reactive nitrogen species, its sources, and their role in ozone formation. In this presentation we shall describe the results from these studies.

Fine-Structure Measurements of Oxygen A Band Absorbance for Estimating the Thermodynamic Average Temperature of the Earth's Atmosphere: An Experiment in Physical and Environmental Chemistry

ERIC Educational Resources Information Center

Myrick, M. L.; Greer, A. E.; Nieuwland, A.; Priore, R. J.; Scaffidi, J.; Andreatta, Daniele; Colavita, Paula

2006-01-01

The experiment describe the measures of the A band transitions of atmospheric oxygen, a rich series of rotation-electronic absorption lines falling in the deep red portion of the optical spectrum and clearly visible owing to attenuation of solar radiation. It combines pure physical chemistry with analytical and environmental science and provides a…

Mass Spectrometry of Single Particles Levitated in an Electrodynamic Balance: Applications to Laboratory Atmospheric Chemistry Research

NASA Astrophysics Data System (ADS)

Birdsall, A.; Krieger, U. K.; Keutsch, F. N.

2017-12-01

Dynamic changes to atmospheric aerosol particle composition (e.g., originating from evaporation/condensation, oxidative aging, or aqueous-phase chemical reactions) impact particle properties with importance for understanding particle effects on climate and human health. These changes can take place over the entire lifetime of an atmospheric particle, which can extend over multiple days. Previous laboratory studies of such processes have included analyzing single particles suspended in a levitation device, such as an electrodynamic balance (EDB), an optical levitator, or an acoustic trap, using optical detection techniques. However, studying chemically complex systems can require an analytical method, such as mass spectrometry, that provides more molecular specificity. Existing work coupling particle levitation with mass spectrometry is more limited and largely has consisted of acoustic levitation of millimeter-sized droplets.In this work an EDB has been coupled with a custom-built ionization source and commercial time-of-flight mass spectrometer (MS) as a platform for laboratory atmospheric chemistry research. Single charged particles (radius 10 μm) have been injected into an EDB, levitated for an arbitrarily long period of time, and then transferred to a vaporization-corona discharge ionization region for MS analysis. By analyzing a series of particles of identical composition, residing in the controlled environment of the EDB for varying times, we can trace the chemical evolution of a particle over hours or days, appropriate timescales for understanding transformations of atmospheric particles.To prove the concept of our EDB-MS system, we have studied the evaporation of particles consisting of polyethylene glycol (PEG) molecules of mixed chain lengths, used as a benchmark system. Our system can quantify the composition of single particles (see Figure for sample spectrum of a single PEG-200 particle: PEG parent ions labeled with m/z, known PEG fragment ions

Summary of the Atmospheric Test Data (Film Scanning and Re-Analysis) Project at LLNL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murray, S. D.

2017-03-21

The goal of the Atmospheric Test Data (ATD) Project is to preserve and make better use of scientific-quality films that were taken during the era of above ground nuclear testing. The project is being done in collaboration with Los Alamos National Laboratory, which is the custodian of the films. Our primary points of contact at LANL have been Alan Carr, Carla Breiner, and Randy Drake.

Toward an Improved Representation of Middle Atmospheric Dynamics Thanks to the ARISE Project

NASA Astrophysics Data System (ADS)

Blanc, E.; Ceranna, L.; Hauchecorne, A.; Charlton-Perez, A.; Marchetti, E.; Evers, L. G.; Kvaerna, T.; Lastovicka, J.; Eliasson, L.; Crosby, N. B.; Blanc-Benon, P.; Le Pichon, A.; Brachet, N.; Pilger, C.; Keckhut, P.; Assink, J. D.; Smets, P. S. M.; Lee, C. F.; Kero, J.; Sindelarova, T.; Kämpfer, N.; Rüfenacht, R.; Farges, T.; Millet, C.; Näsholm, S. P.; Gibbons, S. J.; Espy, P. J.; Hibbins, R. E.; Heinrich, P.; Ripepe, M.; Khaykin, S.; Mze, N.; Chum, J.

2018-03-01

This paper reviews recent progress toward understanding the dynamics of the middle atmosphere in the framework of the Atmospheric Dynamics Research InfraStructure in Europe (ARISE) initiative. The middle atmosphere, integrating the stratosphere and mesosphere, is a crucial region which influences tropospheric weather and climate. Enhancing the understanding of middle atmosphere dynamics requires improved measurement of the propagation and breaking of planetary and gravity waves originating in the lowest levels of the atmosphere. Inter-comparison studies have shown large discrepancies between observations and models, especially during unresolved disturbances such as sudden stratospheric warmings for which model accuracy is poorer due to a lack of observational constraints. Correctly predicting the variability of the middle atmosphere can lead to improvements in tropospheric weather forecasts on timescales of weeks to season. The ARISE project integrates different station networks providing observations from ground to the lower thermosphere, including the infrasound system developed for the Comprehensive Nuclear-Test-Ban Treaty verification, the Lidar Network for the Detection of Atmospheric Composition Change, complementary meteor radars, wind radiometers, ionospheric sounders and satellites. This paper presents several examples which show how multi-instrument observations can provide a better description of the vertical dynamics structure of the middle atmosphere, especially during large disturbances such as gravity waves activity and stratospheric warming events. The paper then demonstrates the interest of ARISE data in data assimilation for weather forecasting and re-analyzes the determination of dynamics evolution with climate change and the monitoring of atmospheric extreme events which have an atmospheric signature, such as thunderstorms or volcanic eruptions.

Integrated Meteorology and Chemistry Modeling: Evaluation and Research Needs

EPA Science Inventory

Over the past decade several online integrated atmospheric chemical-transport and meteorology modeling systems with varying levels of interactions among different atmospheric processes have been developed. A variety of approaches to meteorology-chemistry integration with differe...

Ground-based Observations and Atmospheric Modelling of Energetic Electron Precipitation Effects on Antarctic Mesospheric Chemistry

NASA Astrophysics Data System (ADS)

Newnham, D.; Clilverd, M. A.; Horne, R. B.; Rodger, C. J.; Seppälä, A.; Verronen, P. T.; Andersson, M. E.; Marsh, D. R.; Hendrickx, K.; Megner, L. S.; Kovacs, T.; Feng, W.; Plane, J. M. C.

2016-12-01

The effect of energetic electron precipitation (EEP) on the seasonal and diurnal abundances of nitric oxide (NO) and ozone in the Antarctic middle atmosphere during March 2013 to July 2014 is investigated. Geomagnetic storm activity during this period, close to solar maximum, was driven primarily by impulsive coronal mass ejections. Near-continuous ground-based atmospheric measurements have been made by a passive millimetre-wave radiometer deployed at Halley station (75°37'S, 26°14'W, L = 4.6), Antarctica. This location is directly under the region of radiation-belt EEP, at the extremity of magnetospheric substorm-driven EEP, and deep within the polar vortex during Austral winter. Superposed epoch analyses of the ground based data, together with NO observations made by the Solar Occultation For Ice Experiment (SOFIE) onboard the Aeronomy of Ice in the Mesosphere (AIM) satellite, show enhanced mesospheric NO following moderate geomagnetic storms (Dst ≤ -50 nT). Measurements by co-located 30 MHz riometers indicate simultaneous increases in ionisation at 75-90 km directly above Halley when Kp index ≥ 4. Direct NO production by EEP in the upper mesosphere, versus downward transport of NO from the lower thermosphere, is evaluated using a new version of the Whole Atmosphere Community Climate Model incorporating the full Sodankylä Ion Neutral Chemistry Model (WACCM SIC). Model ionization rates are derived from the Polar orbiting Operational Environmental Satellites (POES) second generation Space Environment Monitor (SEM 2) Medium Energy Proton and Electron Detector instrument (MEPED). The model data are compared with observations to quantify the impact of EEP on stratospheric and mesospheric odd nitrogen (NOx), odd hydrogen (HOx), and ozone.

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.

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.

National Chemistry Week 2000: JCE Resources in Food Chemistry

NASA Astrophysics Data System (ADS)

Jacobsen, Erica K.

2000-10-01

November brings another National Chemistry Week, and this year's theme is food chemistry. I was asked to collect and evaluate JCE resources for use with this theme, a project that took me deep into past issues of JCE and yielded many treasures. Here we present the results of searches for food chemistry information and activities. While the selected articles are mainly at the high school and college levels, there are some excellent ones for the elementary school level and some that can be adapted for younger students. The focus of all articles is on the chemistry of food itself. Activities that only use food to demonstrate a principle other than food chemistry are not included. Articles that cover household products such as cleansers and pharmaceuticals are also not included. Each article has been characterized as a demonstration, experiment, calculation, activity, or informational item; several fit more than one classification. Also included are keywords and an evaluation as to which levels the article may serve.

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

Atmosphere aerosol satellite project Aerosol-UA

NASA Astrophysics Data System (ADS)

Milinevsky, Gennadi; Yatskiv, Yaroslav; Syniavskyi, Ivan; Bovchaliuk, Andrii; Degtyaryov, Oleksandr; Sosonkin, Mikhail; Mishchenko, Michael; Danylevsky, Vassyl; Ivanov, Yury; Oberemok, Yevgeny; Masley, Volodymyr; Rosenbush, Vera; Moskalev, Sergii

2017-04-01

The experiment Aerosol-UA is Ukrainian space mission aimed to the terrestrial atmospheric aerosol spatial distribution and microphysics investigations. The experiment concept is based on idea of Glory/APS mission of precise orbital measurements of polarization and intensity of the sunlight scattered by the atmosphere, aerosol and the surface the multichannel Scanning Polarimeter (ScanPol) with narrow field-of-view. ScanPol measurements will be accompanied by the wide-angle MultiSpectral Imager-Polarimeter (MSIP). The ScanPol is designed to measure Stokes parameters I, Q, U within the spectral range from the UV to the SWIR in a wide range of phase angles along satellite ground path. Expected ScanPol polarimetric accuracy is 0.15%. A high accuracy measurement of the degree of linear polarization is provided by on-board calibration of the ScanPol polarimeter. On-board calibration is performed for each scan of the mirror scanning system. A set of calibrators is viewed during the part of the scan range when the ScanPol polarimeter looks in the direction opposite to the Earth's surface. These reference assemblies provide calibration of the zero of the polarimetric scale (unpolarized reference assembly) and the scale factor for the polarimetric scale (polarized reference assembly). The zero of the radiometric scale is provided by the dark reference assembly.The spectral channels of the ScanPol are used to estimate the tropospheric aerosol absorption, the aerosol over the ocean and the land surface, the signals from cirrus clouds, stratospheric aerosols caused by major volcanic eruptions, and the contribution of the Earth's surface. The imager-polarimeter MSIP will collect 60°x60° field-of-view images on the state of the atmosphere and surface in the area, where the ScanPol polarimeter will measure, to retrieve aerosol optical depth and polarization properties of aerosol by registration of three Stokes parameters simultaneously in three spectral channels. The two more

Titan's Complex Chemistry: Insights from the Lab

NASA Astrophysics Data System (ADS)

Horst, Sarah

2018-06-01

The Cassini-Huygens mission revealed Titan to be a complex world with physical processes reminiscent of other terrestrial planets, but chemistry that is unlike anywhere else in the Solar System. Titan's complex atmospheric chemistry converts N2 and CH4 into numerous, abundant organic molecules ranging from relatively simple hydrocarbons to ions with mass to charge ratios up to 10,000 amu/q. The molecules eventually settle to the surface where they can participate in and be modified by geological processes such as aeolian and fluvial erosion or undergo subsequent chemistry in Titan's lakes and seas or impact craters and potential cryovolcanic flows. From the processes leading to massive ion formation in the atmosphere to the behavior of saltating organic sands on the surface, laboratory experiments are playing a pivotal role in understanding Titan and expanding our understanding of planetary processes into new, exciting phase space.

Tropospheric jet response to Antarctic ozone depletion: An update with Chemistry-Climate Model Initiative (CCMI) models

NASA Astrophysics Data System (ADS)

Son, Seok-Woo; Han, Bo-Reum; Garfinkel, Chaim I.; Kim, Seo-Yeon; Park, Rokjin; Abraham, N. Luke; Akiyoshi, Hideharu; Archibald, Alexander T.; Butchart, N.; Chipperfield, Martyn P.; Dameris, Martin; Deushi, Makoto; Dhomse, Sandip S.; Hardiman, Steven C.; Jöckel, Patrick; Kinnison, Douglas; Michou, Martine; Morgenstern, Olaf; O’Connor, Fiona M.; Oman, Luke D.; Plummer, David A.; Pozzer, Andrea; Revell, Laura E.; Rozanov, Eugene; Stenke, Andrea; Stone, Kane; Tilmes, Simone; Yamashita, Yousuke; Zeng, Guang

2018-05-01

The Southern Hemisphere (SH) zonal-mean circulation change in response to Antarctic ozone depletion is re-visited by examining a set of the latest model simulations archived for the Chemistry-Climate Model Initiative (CCMI) project. All models reasonably well reproduce Antarctic ozone depletion in the late 20th century. The related SH-summer circulation changes, such as a poleward intensification of westerly jet and a poleward expansion of the Hadley cell, are also well captured. All experiments exhibit quantitatively the same multi-model mean trend, irrespective of whether the ocean is coupled or prescribed. Results are also quantitatively similar to those derived from the Coupled Model Intercomparison Project phase 5 (CMIP5) high-top model simulations in which the stratospheric ozone is mostly prescribed with monthly- and zonally-averaged values. These results suggest that the ozone-hole-induced SH-summer circulation changes are robust across the models irrespective of the specific chemistry-atmosphere-ocean coupling.

Aviation Trends Related to Atmospheric Environment Safety Technologies Project Technical Challenges

NASA Technical Reports Server (NTRS)

Reveley, Mary S.; Withrow, Colleen A.; Barr, Lawrence C.; Evans, Joni K.; Leone, Karen M.; Jones, Sharon M.

2014-01-01

Current and future aviation safety trends related to the National Aeronautics and Space Administration's Atmospheric Environment Safety Technologies Project's three technical challenges (engine icing characterization and simulation capability; airframe icing simulation and engineering tool capability; and atmospheric hazard sensing and mitigation technology capability) were assessed by examining the National Transportation Safety Board (NTSB) accident database (1989 to 2008), incidents from the Federal Aviation Administration (FAA) accident/incident database (1989 to 2006), and literature from various industry and government sources. The accident and incident data were examined for events involving fixed-wing airplanes operating under Federal Aviation Regulation (FAR) Parts 121, 135, and 91 for atmospheric conditions related to airframe icing, ice-crystal engine icing, turbulence, clear air turbulence, wake vortex, lightning, and low visibility (fog, low ceiling, clouds, precipitation, and low lighting). Five future aviation safety risk areas associated with the three AEST technical challenges were identified after an exhaustive survey of a variety of sources and include: approach and landing accident reduction, icing/ice detection, loss of control in flight, super density operations, and runway safety.

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.

D-region ion-neutral coupled chemistry (Sodankylä Ion Chemistry, SIC) within the Whole Atmosphere Community Climate Model (WACCM 4) - WACCM-SIC and WACCM-rSIC

NASA Astrophysics Data System (ADS)

Kovács, Tamás; Plane, John M. C.; Feng, Wuhu; Nagy, Tibor; Chipperfield, Martyn P.; Verronen, Pekka T.; Andersson, Monika E.; Newnham, David A.; Clilverd, Mark A.; Marsh, Daniel R.

2016-09-01

This study presents a new ion-neutral chemical model coupled into the Whole Atmosphere Community Climate Model (WACCM). The ionospheric D-region (altitudes ˜ 50-90 km) chemistry is based on the Sodankylä Ion Chemistry (SIC) model, a one-dimensional model containing 307 ion-neutral and ion recombination, 16 photodissociation and 7 photoionization reactions of neutral species, positive and negative ions, and electrons. The SIC mechanism was reduced using the simulation error minimization connectivity method (SEM-CM) to produce a reaction scheme of 181 ion-molecule reactions of 181 ion-molecule reactions of 27 positive and 18 negative ions. This scheme describes the concentration profiles at altitudes between 20 km and 120 km of a set of major neutral species (HNO3, O3, H2O2, NO, NO2, HO2, OH, N2O5) and ions (O2+, O4+, NO+, NO+(H2O), O2+(H2O), H+(H2O), H+(H2O)2, H+(H2O)3, H+(H2O)4, O3-, NO2-, O-, O2, OH-, O2-(H2O), O2-(H2O)2, O4-, CO3-, CO3-(H2O), CO4-, HCO3-, NO2-, NO3-, NO3-(H2O), NO3-(H2O)2, NO3-(HNO3), NO3-(HNO3)2, Cl-, ClO-), which agree with the full SIC mechanism within a 5 % tolerance. Four 3-D model simulations were then performed, using the impact of the January 2005 solar proton event (SPE) on D-region HOx and NOx chemistry as a test case of four different model versions: the standard WACCM (no negative ions and a very limited set of positive ions); WACCM-SIC (standard WACCM with the full SIC chemistry of positive and negative ions); WACCM-D (standard WACCM with a heuristic reduction of the SIC chemistry, recently used to examine HNO3 formation following an SPE); and WACCM-rSIC (standard WACCM with a reduction of SIC chemistry using the SEM-CM method). The standard WACCM misses the HNO3 enhancement during the SPE, while the full and reduced model versions predict significant NOx, HOx and HNO3 enhancements in the mesosphere during solar proton events. The SEM-CM reduction also identifies the important ion-molecule reactions that affect the partitioning of

A survey of bimolecular ion-molecule reactions for use in modeling the chemistry of planetary atmospheres, cometary comae, and interstellar clouds

NASA Technical Reports Server (NTRS)

Anicich, V. G.; Huntress, W. T., Jr.

1986-01-01

All bimolecular positive ion-molecule reactions reported from 1965 to 1985 for temperatures below 1000 K are included in the present survey of those ion-molecule reactions pertinent to the chemistries of planetary atmospheres, cometary comae, and interstellar clouds. This survey is intended as an update of the first, by Huntress (1977). The tabular presentation is organized according to reactant ion, with cross-references for both the ionic and the neutral reactants as well as the ionic and neutral products.

Towards a Comprehensive Dynamic-chemistry Assimilation for Eos-Chem: Plans and Status in NASA's Data Assimilation Office

NASA Technical Reports Server (NTRS)

Pawson, Steven; Lin, Shian-Jiann; Rood, Richard B.; Stajner, Ivanka; Nebuda, Sharon; Nielsen, J. Eric; Douglass, Anne R.

2000-01-01

In order to support the EOS-Chem project, a comprehensive assimilation package for the coupled chemical-dynamical system is being developed by the Data Assimilation Office at NASA GSFC. This involves development of a coupled chemistry/meteorology model and of data assimilation techniques for trace species and meteorology. The model is being developed using the flux-form semi-Lagrangian dynamical core of Lin and Rood, the physical parameterizations from the NCAR Community Climate Model, and atmospheric chemistry modules from the Atmospheric Chemistry and Dynamics branch at NASA GSFC. To date the following results have been obtained: (i) multi-annual simulations with the dynamics-radiation model show the credibility of the package for atmospheric simulations; (ii) initial simulations including a limited number of middle atmospheric trace gases reveal the realistic nature of transport mechanisms, although there is still a need for some improvements. Samples of these results will be shown. A meteorological assimilation system is currently being constructed using the model; this will form the basis for the proposed meteorological/chemical assimilation package. The latter part of the presentation will focus on areas targeted for development in the near and far terms, with the objective of Providing a comprehensive assimilation package for the EOS-Chem science experiment. The first stage will target ozone assimilation. The plans also encompass a reanalysis (ReSTS) for the 1991-1995 period, which includes the Mt. Pinatubo eruption and the time when a large number of UARS observations were available. One of the most challenging aspects of future developments will be to couple theoretical advances in tracer assimilation with the practical considerations of a real environment and eventually a near-real-time assimilation system.

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

Virtually going green: The role of quantum computational chemistry in reducing pollution and toxicity in chemistry

NASA Astrophysics Data System (ADS)

Stevens, Jonathan

2017-07-01

Continuing advances in computational chemistry has permitted quantum mechanical calculation to assist in research in green chemistry and to contribute to the greening of chemical practice. Presented here are recent examples illustrating the contribution of computational quantum chemistry to green chemistry, including the possibility of using computation as a green alternative to experiments, but also illustrating contributions to greener catalysis and the search for greener solvents. Examples of applications of computation to ambitious projects for green synthetic chemistry using carbon dioxide are also presented.

NEW DIRECTIONS: VOCS AND BIOSPHERE-ATMOSPHERE FEEDBACKS

EPA Science Inventory

Shallcross and Monks [New Directions: a Role For Isoprene in Biosphere-Climate-Chemistry Feedbacks, Atmospheric Environment, Vol. 34 (2000) pp. 1659-1660] recently summarized the importance of biogenic isoprene in a biosphere-atmosphere system under constant change. In this art...

Indoor chemistry: research opportunities and challenges.

PubMed

Nazaroff, W W; Goldstein, A H

2015-08-01

In this editorial, we have highlighted key research opportunities and challenges in four topical themes for indoor chemistry: human occupants as agents influencing indoor chemistry; oxidative chemistry; surface phenomena; and semivolatile organic compounds. In each case, enough prior work has been done to demonstrate the importance of the theme and to create a foundation for future studies. Extensive achievements and ongoing progress in (outdoor) atmospheric chemistry—both in the analytical methods developed and in the scientific knowledge created—also contribute to a strong foundation from which to achieve rapid research progress in this exciting new domain.

Chemical Composition of the Atmosphere

NASA Astrophysics Data System (ADS)

Schlager, Hans; Grewe, Volker; Roiger, Anke

Atmospheric trace gases have an important impact on Earth's radiative budget, the oxidative or cleansing ability of the atmosphere, the formation, growth and properties of aerosols, air quality, and human health. During recent years, the coupling between atmospheric chemistry and climate has received particular attention. Therefore, research is now focused on the composition and processes in the upper troposphere and lower stratosphere, a key region in this respect. In this chapter the chemical composition of the atmosphere is addressed and selected examples of significant advances in this field are presented.

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

NASA Technical Reports Server (NTRS)

Hirasawa, T.

1982-01-01

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

Organic chemistry on Titan

NASA Technical Reports Server (NTRS)

Chang, S.; Scattergood, T.; Aronowitz, S.; Flores, J.

1979-01-01

Features taken from various models of Titan's atmosphere are combined in a working composite model that provides environmental constraints within which different pathways for organic chemical synthesis are determined. Experimental results and theoretical modeling suggest that the organic chemistry of the satellite is dominated by two processes: photochemistry and energetic particle bombardment. Photochemical reactions of CH4 in the upper atmosphere can account for the presence of C2 hydrocarbons. Reactions initiated at various levels of the atmosphere by cosmic rays, Saturn 'wind', and solar wind particle bombardment of a CH4-N2 atmospheric mixture can account for the UV-visible absorbing stratospheric haze, the reddish appearance of the satellite, and some of the C2 hydrocarbons. In the lower atmosphere photochemical processes will be important if surface temperatures are sufficiently high for gaseous NH3 to exist. It is concluded that the surface of Titan may contain ancient or recent organic matter (or both) produced in the atmosphere.

Effects of different representations of transport in the new EMAC-SWIFT chemistry climate model

NASA Astrophysics Data System (ADS)

Scheffler, Janice; Langematz, Ulrike; Wohltmann, Ingo; Kreyling, Daniel; Rex, Markus

2017-04-01

It is well known that the representation of atmospheric ozone chemistry in weather and climate models is essential for a realistic simulation of the atmospheric state. Interactively coupled chemistry climate models (CCMs) provide a means to realistically simulate the interaction between atmospheric chemistry and dynamics. The calculation of chemistry in CCMs, however, is computationally expensive which renders the use of complex chemistry models not suitable for ensemble simulations or simulations with multiple climate change scenarios. In these simulations ozone is therefore usually prescribed as a climatological field or included by incorporating a fast linear ozone scheme into the model. While prescribed climatological ozone fields are often not aligned with the modelled dynamics, a linear ozone scheme may not be applicable for a wide range of climatological conditions. An alternative approach to represent atmospheric chemistry in climate models which can cope with non-linearities in ozone chemistry and is applicable to a wide range of climatic states is the Semi-empirical Weighted Iterative Fit Technique (SWIFT) that is driven by reanalysis data and has been validated against observational satellite data and runs of a full Chemistry and Transport Model. SWIFT has been implemented into the ECHAM/MESSy (EMAC) chemistry climate model that uses a modular approach to climate modelling where individual model components can be switched on and off. When using SWIFT in EMAC, there are several possibilities to represent the effect of transport inside the polar vortex: the semi-Lagrangian transport scheme of EMAC and a transport parameterisation that can be useful when using SWIFT in models not having transport of their own. Here, we present results of equivalent simulations with different handling of transport, compare with EMAC simulations with full interactive chemistry and evaluate the results with observations.

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.

Chemistry in the Two-Year College. Proceedings from Two-Year College Chemistry Conference and Papers of Special Interest to the Two-Year College Chemistry Teacher. 1971 No. 1.

ERIC Educational Resources Information Center

Chapman, Kenneth, Ed.

In this publication, issued twice per year, four major topics are discussed: (1) chemistry course content, including chemistry for nonscience students and nurses; (2) using media in chemistry, such as behavioral objectives and audio-tutorial aids; (3) chemical technology, with emphasis on the Chemical Technology Curriculum Project (Chem TeC); and…

Satellite Observations of Tropospheric Chemistry

NASA Technical Reports Server (NTRS)

Singh, Hanwant B.; Jacob, Daniel J.; Hipskind, R. Stephen (Technical Monitor)

2001-01-01

The troposphere is an essential component of the earth's life support system as well as the gateway for the exchange of chemicals between different geochemical reservoirs of the earth. The chemistry of the troposphere is sensitive to perturbation from a wide range of natural phenomena and human activities. The societal concern has been greatly enhanced in recent decades due to ever increasing pressures of population growth and industrialization. Chemical changes within the troposphere control a vast array of processes that impact human health, the biosphere, and climate. A main goal of tropospheric chemistry research is to measure and understand the response of atmospheric composition to natural and anthropogenic perturbations, and to develop the capability to predict future change. Atmospheric chemistry measurements are extremely challenging due to the low concentrations of critical species and the vast scales over which the observations must be made. Available tropospheric data are mainly from surface sites and aircraft missions. Because of the limited temporal extent of aircraft observations, we have very limited information on tropospheric composition above the surface. This situation can be contrasted to the stratosphere, where satellites have provided critical and detailed chemical data on the global distribution of key trace gases.

SIOUX project: a simultaneous multiband camera for exoplanet atmospheres studies

NASA Astrophysics Data System (ADS)

Christille, Jean Marc; Bonomo, Aldo Stefano; Borsa, Francesco; Busonero, Deborah; Calcidese, Paolo; Claudi, Riccardo; Damasso, Mario; Giacobbe, Paolo; Molinari, Emilio; Pace, Emanuele; Riva, Alberto; Sozzetti, Alesandro; Toso, Giorgio; Tresoldi, Daniela

2016-08-01

The exoplanet revolution is well underway. The last decade has seen order-of-magnitude increases in the number of known planets beyond the Solar system. Detailed characterization of exoplanetary atmospheres provide the best means for distinguishing the makeup of their outer layers, and the only hope for understanding the interplay between initial composition chemistry, temperature-pressure atmospheric profiles, dynamics and circulation. While pioneering work on the observational side has produced the first important detections of atmospheric molecules for the class of transiting exoplanets, important limitations are still present due to the lack of systematic, repeated measurements with optimized instrumentation at both visible (VIS) and near-infrared (NIR) wavelengths. It is thus of fundamental importance to explore quantitatively possible avenues for improvements. In this paper we report initial results of a feasibility study for the prototype of a versatile multi-band imaging system for very high-precision differential photometry that exploits the choice of specifically selected narrow-band filters and novel ideas for the execution of simultaneous VIS and NIR measurements. Starting from the fundamental system requirements driven by the science case at hand, we describe a set of three opto-mechanical solutions for the instrument prototype: 1) a radial distribution of the optical flux using dichroic filters for the wavelength separation and narrow-band filters or liquid crystal filters for the observations; 2) a tree distribution of the optical flux (implying 2 separate foci), with the same technique used for the beam separation and filtering; 3) an 'exotic' solution consisting of the study of a complete optical system (i.e. a brand new telescope) that exploits the chromatic errors of a reflecting surface for directing the different wavelengths at different foci. In this paper we present the first results of the study phase for the three solutions, as well as the

Bioorganic and bioinorganic chemistry.

PubMed

Constable, Edwin C; Housecroft, Catherine E; Creus, Marc; Gademann, Karl; Giese, Bernd; Ward, Thomas R; Woggon, Wolf D; Chougnet, Antoinette

2010-01-01

The interdisciplinary projects in bioinorganic and bioorganic chemistry of the Department of Chemistry, University of Basel led to the preparation of new systems that mimic biologically important processes and to the discovery of compounds from natural sources which are very promising with respect to medical applications. The advances in these areas are reported here.

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

Kinetic and spectroscopic studies of peroxy radical reactions related to tropospheric photo-oxidation chemistry

NASA Astrophysics Data System (ADS)

Jenkin, Michael Edwin

Over the past 30 years, man has become increasingly aware that the presence of relatively small quantities of pollutants in the atmosphere as a result of his activities, can have a profound impact on both its chemistry, and its meteorology. Photochemistry in the atmosphere is not restricted to the behavior of pollutants; indeed, certain photochemical phenomena necessarily occur naturally in a 'pollution free' atmosphere. It is the interaction of the photochemistry of trace pollutants with the naturally established chemistry, either inhibiting or exaggerating natural processes, which has given rise to the environment threatening consequences. The chemistry that leads to the phenomena mentioned above is complex, involving many hundreds of chemical reactions of reactive atomic and radical species. Over the years, a great deal of chemical kinetic data for elementary atmospheric reactions has accumulated, and the fundamental gas phase chemistry is well established. Computer models provide a useful means of assembling these data, and describing the likely behavior and interconversion of various atmospheric pollutants, thereby enabling policy decision. For these models to be truly predictive, however, they must be based, first on reliable field measurements of primary trace pollutants and, secondly, on accurate kinetic and mechanistic data for key reactions of atmospheric importance. The work presented in this dissertation is concerned with the kinetics and mechanisms of reactions of the hydroperoxy radial (HO2), and various organic peroxy radicals (RO2), which are formed as intermediates in the atmospheric oxidation of volatile organic compounds. In the sections that follow, our current understanding of the chemistry in general of the lower atmosphere (0-50 km) will be discussed in some detail, but with particular reference to the role played by HO2 and RO2 radicals.

Kinetic and Spectroscopic Studies of Peroxy Radical Reactions Related to Tropospheric Photo-Oxidation Chemistry

NASA Astrophysics Data System (ADS)

Jenkin, Michael Edwin

1991-05-01

Available from UMI in association with The British Library. Over the past 30 years, man has become increasingly aware that the presence of relatively small quantities of pollutants in the atmosphere as a result of his activities, can have a profound impact on both its chemistry, and its meteorology. Photochemistry in the atmosphere is not restricted to the behaviour of pollutants; indeed, certain photochemical phenomena necessarily occur naturally in a "pollution free" atmosphere. It is the interaction of the photochemistry of trace pollutants with the naturally established chemistry, either inhibiting or exaggerating natural processes, which has given rise to the environment-threatening consequences. The chemistry that leads to the phenomena mentioned above is complex, involving many hundreds of chemical reactions of reactive atomic and radical species. Over the years, a great deal of chemical kinetic data for elementary atmospheric reactions has accumulated^{(5,6)} , and the fundamental gas phase chemistry is well established. Computer models provide a useful means of assembling these data, and describing the likely behaviour and interconversion of various atmospheric pollutants, thereby enabling policy decision. For these models to be truly predictive, however, they must be based, first on reliable field measurements of primary trace pollutants and, secondly, on accurate kinetic and mechanistic data for key reactions of atmospheric importance. The work presented in this dissertation is concerned with the kinetics and mechanisms of reactions of the hydroperoxy radical (HO_2), and various organic peroxy radicals (RO_2) which are formed as intermediates in the atmospheric oxidation of volatile organic compounds. In the sections that follow, our current understanding of the chemistry in general of the lower atmosphere (0-50 km) will be discussed in some detail, but with particular reference to the role played by HO_2 and RO_2 radicals. (Abstract shortened by UMI.).

Mercury in the global atmosphere: Chemistry, deposition, and land-atmosphere interactions

NASA Astrophysics Data System (ADS)

Selin, Noelle Eckley

This thesis uses a global 3-D chemical transport model (GEOS-Chem), in conjunction with worldwide atmospheric observations, to better understand and quantify biogeochemical cycling and deposition of mercury. GEOS-Chem includes gaseous elemental (Hg(0)), divalent (Hg(II)), and particulate (Hg(P)) mercury in the atmosphere, and includes coupling with the ocean, developed at University of Washington, and with land, developed in this work. Observed concentrations and seasonal variation of total gaseous mercury (TGM) are consistent with photochemical oxidation for Hg(0) partly balanced by in-cloud photochemical reduction of Hg(II). High TGM concentrations from ship cruises in the Northern Hemisphere are not reproduced, implying a problem either in measurements or our understanding of sources. Model results, supported by observations, suggest Hg(II) to be dominant at higher altitudes. Diurnal variability observed at marine sites suggests uptake by sea salt aerosols is a major deposition mechanism. Global biogeochemical cycles of mercury are constructed for pre-industrial and present-day using the first fully-coupled, global 3-D land-atmosphere-ocean mercury model. Atmosphere-surface cycling increases the effective mercury lifetime more than threefold against transfer to long-lived soil and ocean reservoirs. It is estimated that 68% of deposition to the U.S. is anthropogenic, including 16% from the legacy of anthropogenic mercury accumulated in soils and the deep ocean. Observed seasonal variations in U.S. wet deposition are used to constrain redox and deposition processes influencing the fate of North American and international emissions. The model reproduces the seasonal variation and latitudinal gradient of wet deposition flux measured in the eastern U.S., with a maximum in the Southeast and higher fluxes in summer and at lower latitudes. Seasonal variation is attributed to variations in oxidation and wet deposition rates at northern latitudes, and to seasonal

Chemistry Modeling for Aerothermodynamics and TPS

NASA Technical Reports Server (NTRS)

Wang, Dunyou; Stallcop, James R.; Dateo, Christopher e.; Schwenke, David W.; Halicioglu, Timur; Huo, winifred M.

2005-01-01

Recent advances in supercomputers and highly scalable quantum chemistry software render computational chemistry methods a viable means of providing chemistry data for aerothermal analysis at a specific level of confidence. Four examples of first principles quantum chemistry calculations will be presented. Study of the highly nonequilibrium rotational distribution of a nitrogen molecule from the exchange reaction N + N2 illustrates how chemical reactions can influence rotational distribution. The reaction C2H + H2 is one example of a radical reaction that occurs during hypersonic entry into an atmosphere containing methane. A study of the etching of a Si surface illustrates our approach to surface reactions. A recently developed web accessible database and software tool (DDD) that provides the radiation profile of diatomic molecules is also described.

Chemistry Modeling for Aerothermodynamics and TPS

NASA Technical Reports Server (NTRS)

Wang, Dun-You; Stallcop, James R.; Dateo, Christopher E.; Schwenke, David W.; Haliciogiu, Timur; Huo, Winifred

2004-01-01

Recent advances in supercomputers and highly scalable quantum chemistry software render computational chemistry methods a viable means of providing chemistry data for aerothermal analysis at a specific level of confidence. Four examples of first principles quantum chemistry calculations will be presented. The study of the highly nonequilibrium rotational distribution of nitrogen molecule from the exchange reaction N + N2 illustrates how chemical reactions can influence the rotational distribution. The reaction C2H + H2 is one example of a radical reaction that occurs during hypersonic entry into a methane containing atmosphere. A study of the etching of Si surface illustrates our approach to surface reactions. A recently developed web accessible database and software tool (DDD) that provides the radiation profile of diatomic molecules is also described.

Urban impact on air quality in RegCM/CAMx couple for MEGAPOLI project - high resolution sensitivity study

NASA Astrophysics Data System (ADS)

Halenka, T.; Huszar, P.; Belda, M.

2010-09-01

Recent studies show considerable effect of atmospheric chemistry and aerosols on climate on regional and local scale. For the purpose of qualifying and quantifying the magnitude of climate forcing due to atmospheric chemistry/aerosols on regional scale, the development of coupling of regional climate model and chemistry/aerosol model was started on the Department of Meteorology and Environmental Protection, Charles University, Prague, for the EC FP6 Project QUANTIFY and EC FP6 Project CECILIA. For this coupling, existing regional climate model and chemistry transport model have been used at very high resolution of 10km grid. Climate is calculated using RegCM while chemistry is solved by CAMx. The experiments with the couple have been prepared for EC FP7 project MEGAPOLI assessing the impact of the megacities and industrialized areas on climate. Meteorological fields generated by RCM drive CAMx transport, chemistry and a dry/wet deposition. A preprocessor utility was developed for transforming RegCM provided fields to CAMx input fields and format. New domain have been settled for MEGAPOLI purpose in 10km resolution including all the European "megacities" regions, i.e. London metropolitan area, Paris region, industrialized Ruhr area, Po valley etc. There is critical issue of the emission inventories available for 10km resolution including the urban hot-spots, TNO emissions are adopted for this sensitivity study in 10km resolution for comparison of the results with the simulation based on merged TNO emissions, i.e. basically original EMEP emissions at 50 km grid. The sensitivity test to switch on/off Paris area emissions is analysed as well. Preliminary results for year 2005 are presented and discussed to reveal whether the concept of effective emission indices could help to parameterize the urban plume effects in lower resolution models. Interactive coupling is compared to study the potential of possible impact of urban air-pollution to the urban area climate.

Model Atmospheres and Transit Spectra for Hot Rocky Planets

NASA Astrophysics Data System (ADS)

Lupu, Roxana

hot Jupiters in similar transit configurations. For example, Na has been the first species to be detected in an exoplanet atmosphere, by observing the evaporating hotJupiter HD209458b. Understanding the interplay between the magma outgassing and volatile loss will be an important part of this project. Our team has the expertise in the chemistry, radiative transfer, and atmospheric escape modeling at these exotic temperatures. Our recent work has analyzed the emerging atmospheres of terrestrial planets after giant impacts, using a well-established radiativeconvective atmospheric structure code, with an extensive opacity database for all relevant molecules, and the chemistry self-consistently calculated for continental crust and bulk silicate earth compositions. We will expand on this work by considering a wider range of chemical compositions, assessing the importance of clouds and generating cloudy models, and developing dis-equilibrium models by taking into account vertical mixing and photochemistry. Photo-evaporation will be considered in the energy balance between heating, cooling and mass loss. We also have in-house codes to generate high-resolution eclipse spectra and predict transit depths and observable signatures. The development of the atmospheric code, the molecular opacity updates, the atmospheric structure calculations and the high resolution eclipse spectra will be performed by R. Lupu, M. Marley, and R. Freedman at NASA Ames. The atmospheric chemistry grids will be provided by B. Fegley and K. Lodders at Washington University. The transit spectra and observational features will be computed by J. Fortney at UCSC, and the atmospheric escape calculations will be performed by K. Zahnle at NASA Ames. This proposal addresses the following goals of the Exoplanet Research program: explain observations of exoplanetary systems, and understand the chemical and physical processes of exoplanets. Our results will also inform future JWST observations.

A model to calculate consistent atmospheric emission projections and its application to Spain

NASA Astrophysics Data System (ADS)

Lumbreras, Julio; Borge, Rafael; de Andrés, Juan Manuel; Rodríguez, Encarnación

Global warming and air quality are headline environmental issues of our time and policy must preempt negative international effects with forward-looking strategies. As part of the revision of the European National Emission Ceilings Directive, atmospheric emission projections for European Union countries are being calculated. These projections are useful to drive European air quality analyses and to support wide-scale decision-making. However, when evaluating specific policies and measures at sectoral level, a more detailed approach is needed. This paper presents an original methodology to evaluate emission projections. Emission projections are calculated for each emitting activity that has emissions under three scenarios: without measures (business as usual), with measures (baseline) and with additional measures (target). The methodology developed allows the estimation of highly disaggregated multi-pollutant, consistent emissions for a whole country or region. In order to assure consistency with past emissions included in atmospheric emission inventories and coherence among the individual activities, the consistent emission projection (CEP) model incorporates harmonization and integration criteria as well as quality assurance/quality check (QA/QC) procedures. This study includes a sensitivity analysis as a first approach to uncertainty evaluation. The aim of the model presented in this contribution is to support decision-making process through the assessment of future emission scenarios taking into account the effect of different detailed technical and non-technical measures and it may also constitute the basis for air quality modelling. The system is designed to produce the information and formats related to international reporting requirements and it allows performing a comparison of national results with lower resolution models such as RAINS/GAINS. The methodology has been successfully applied and tested to evaluate Spanish emission projections up to 2020 for 26

Atmospheric Chemistry of Neonicotinoids Used in Urban Areas

NASA Astrophysics Data System (ADS)

Finlayson-Pitts, B. J.; Aregahegn, K.; Shemesh, D.; Gerber, R. B.

2016-12-01

Neonicotinoid (NN) pesticides are used extensively in both urban and agricultural settings to control sucking pests such as aphids, as well as for flea control for domestic pets. As a result, they are commonly found on surfaces that are exposed to the atmosphere. Imidacloprid (IMD) is one of the major NNs in pest control formulations. While there have been a number of studies of IMD reactions in solution, there are relatively few surface reactions that are relevant to atmospheric exposures. We report here laboratory studies of the photochemistry of IMD on surfaces in which quantum yields are measured and combined with absorption cross sections to estimate tropospheric lifetimes with respect to photolysis. Products identified using a combination of ATR-FTIR, DART-MS and ESI-MS include the desnitro and urea derivatives in the solid, and N2O in the gas phase. Quantum chemical calculations suggest a mechanism for the photolysis and production of these products. The implications for altering toxicity through atmospheric reactions will be discussed.

Evaluation of a Mineral Dust Simulation in the Atmospheric-Chemistry General Circulation Model-EMAC

NASA Astrophysics Data System (ADS)

Abdel Kader, M.; Astitha, M.; Lelieveld, J.

2012-04-01

This study presents an evaluation of the atmospheric mineral dust cycle in the Atmospheric Chemistry General Circulation Model (AC-GCM) using new developed dust emissions scheme. The dust cycle, as an integral part of the Earth System, plays an important role in the Earth's energy balance by both direct and indirect ways. As an aerosol, it significantly impacts the absorption and scattering of radiation in the atmosphere and can modify the optical properties of clouds and snow/ice surfaces. In addition, dust contributes to a range of physical, chemical and bio-geological processes that interact with the cycles of carbon and water. While our knowledge of the dust cycle, its impacts and interactions with the other global-scale bio-geochemical cycles has greatly advanced in the last decades, large uncertainties and knowledge gaps still exist. Improving the dust simulation in global models is essential to minimize the uncertainties in the model results related to dust. In this study, the results are based on the ECHAM5 Modular Earth Submodel System (MESSy) AC-GCM simulations using T106L31 spectral resolution (about 120km ) with 31 vertical levels. The GMXe aerosol submodel is used to simulate the phase changes of the dust particles between soluble and insoluble modes. Dust emission, transport and deposition (wet and dry) are calculated on-line along with the meteorological parameters in every model time step. The preliminary evaluation of the dust concentration and deposition are presented based on ground observations from various campaigns as well as the evaluation of the optical properties of dust using AERONET and satellite (MODIS and MISR) observations. Preliminarily results show good agreement with observations for dust deposition and optical properties. In addition, the global dust emissions, load, deposition and lifetime is in good agreement with the published results. Also, the uncertainties in the dust cycle that contribute to the overall model performance

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.

Regional Air Quality Model Application of the Aqueous-Phase Photo Reduction of Atmospheric Oxidized Mercury by Dicarboxylic Acids

EPA Science Inventory

In most ecosystems, atmospheric deposition is the primary input of mercury. The total wet deposition of mercury in atmospheric chemistry models is sensitive to parameterization of the aqueous-phase reduction of divalent oxidized mercury (Hg2+). However, most atmospheric chemistry...

Observations of Inland Snowpack-driven Bromine Chemistry near the Brooks Range, Alaska

NASA Astrophysics Data System (ADS)

Peterson, P.; Pöhler, D.; Sihler, H.; Zielcke, J.; S., General; Friess, U.; Platt, U.; Simpson, W. R.; Nghiem, S. V.; Shepson, P. B.; Stirm, B. H.; Pratt, K.

2017-12-01

The snowpack produces high amounts of reactive bromine in the polar regions during spring. The resulting atmospheric bromine chemistry depletes boundary layer ozone to near-zero levels and alters oxidation of atmospheric pollutants, particularly elemental mercury. To improve our understanding of the spatial extent of this bromine chemistry in Arctic coastal regions, the Purdue Airborne Laboratory for Atmospheric Research (ALAR), equipped with the Heidelberg Imaging differential optical absorption spectroscopy (DOAS) instrument, measured the spatial distribution of BrO, an indicator of active bromine chemistry, over northern Alaska during the March 2012 BRomine Ozone Mercury Experiment (BROMEX). Here we show that this bromine chemistry, commonly associated with snow-covered sea ice regions in the Arctic Ocean, is active 200 km inland in the foothills of the Brooks Range. Profiles retrieved from limb-viewing measurements show this event was located near the snowpack surface, with measured BrO mole ratios of 20 pmol mol-1 in a 500 m thick layer. This observed bromine chemistry is likely enabled by deposition of transported sea salt aerosol or gas phase bromine species from prior activation events to the snowpack. These observations of halogen activation hundreds of km from the coast suggest the impacts of this springtime bromine chemistry are not restricted to sea ice regions and directly adjacent coastal regions.

Chemistry Simulations using the MERRA-2 Reanalysis with the GMI CTM and Replay in Support of the Atmospheric Composition Community

NASA Technical Reports Server (NTRS)

Oman, Luke D.; Strahan, Susan E.

2017-01-01

Simulations using reanalysis meteorological fields have long been used to understand the causes of atmospheric composition change in the recent past. Using the new MERRA-2 reanalysis, we are conducting chemistry simulations to create products covering 1980-2016 for the atmospheric composition community. These simulations use the Global Modeling Initiative (GMI) chemical mechanism in two different models: the GMI Chemical Transport Model (CTM) and the GEOS-5 model in Replay mode. Replay mode means an integration of the GEOS-5 general circulation model that is incrementally adjusted each time step toward the MERRA-2 reanalysis. The GMI CTM is a 1 deg x 1.25 deg simulation and the MERRA-2 GMI Replay simulation uses the native MERRA-2 grid of approximately 1/2 deg horizontal resolution on the cubed sphere. A specialized set of transport diagnostics is included in both runs to better understand trace gas transport and its variability in the recent past.

Incorporation of Medicinal Chemistry into the Organic Chemistry Curriculum