WorldWideScience

Sample records for atmospheric composition change

  1. Atmospheric composition change: Ecosystems-Atmosphere interactions

    NARCIS (Netherlands)

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

    2009-01-01

    Ecosystems and the atmosphere: This review describes the state of understanding the processes involved in the exchange of trace gases and aerosols between the earth's surface and the atmosphere. The gases covered include NO, NO2, HONO, HNO3, NH3, SO2, DMS, Biogenic VOC, O-3, CH4, N2O and particles i

  2. Atmospheric composition change: Ecosystems–Atmosphere interactions

    DEFF Research Database (Denmark)

    Fowler, D.; Pilegaard, Kim; Sutton, M.A.

    2009-01-01

    and techniques in micrometeorology. For some of the compounds there have been paradigm shifts in approach and application of both techniques and assessment. These include flux measurements over marine surfaces and urban areas using micrometeorological methods and the up-scaling of flux measurements using...... in the size range 1 nm–10 μm including organic and inorganic chemical species. The main focus of the review is on the exchange between terrestrial ecosystems, both managed and natural and the atmosphere, although some new developments in ocean–atmosphere exchange are included. The material presented is biased...... towards the last decade, but includes earlier work, where more recent developments are limited or absent. New methodologies and instrumentation have enabled, if not driven technical advances in measurement. These developments have advanced the process understanding and upscaling of fluxes, especially...

  3. Atmospheric Composition Change: Climate-Chemistry Interactions

    Science.gov (United States)

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

    2011-01-01

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

  4. Atmospheric composition

    Science.gov (United States)

    Daniels, G. E.

    1973-01-01

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

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

    Science.gov (United States)

    Schuepbach, E.

    2010-09-01

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

  6. Saturn's Seasonally Changing Atmosphere: Thermal Structure, Composition and Aerosols

    CERN Document Server

    Fletcher, Leigh N; Moses, Julianne I; Guerlet, Sandrine; West, Robert A

    2015-01-01

    The longevity of Cassini's exploration of Saturn's atmosphere (a third of a Saturnian year) means that we have been able to track the seasonal evolution of atmospheric temperatures, chemistry and cloud opacity over almost every season, from solstice to solstice and from perihelion to aphelion. Cassini has built upon the decades-long ground-based record to observe seasonal shifts in atmospheric temperature, finding a thermal response that lags behind the seasonal insolation with a lag time that increases with depth into the atmosphere, in agreement with radiative climate models. Seasonal hemispheric contrasts are perturbed at smaller scales by atmospheric circulation, such as belt/zone dynamics, the equatorial oscillations and the polar vortices. Temperature asymmetries are largest in the middle stratosphere and become insignificant near the radiative-convective boundary. Cassini has also measured southern-summertime asymmetries in atmospheric composition, including ammonia (the key species for the topmost clo...

  7. Future changes of the atmospheric composition and the impact of climate change

    Energy Technology Data Exchange (ETDEWEB)

    Grewe, V.; Dameris, M.; Hein, R.; Sausen, R. [DLR Deutsches Zentrum fuer Luft- und Raumfahrt e.V., Wessling (Germany). Inst. fuer Physik der Atmosphaere; Steil, B. [Max-Planck-Institut fuer Chemie (Otto-Hahn-Institut), Mainz (Germany). Abt. Chemie der Atmosphaere

    1999-05-01

    The development of the future atmospheric chemical composition, with respect of NO{sub y} and O{sub 3} is investigated by means of the off-line coupled dynamic-chemical general circulation model ECHAM3/CHEM. Two time slice experiments have been performed for the years 1992 and 2015, which include changes in sea surface temperatures, greenhouse gas concentrations, emissions of CFCs, NO{sub x} and other species, i.e., the 2015 simulation accounts for changes in chemically relevant emissions and for a climate change and its impact on air chemistry. The 2015 simulation clearly shows a global increase in ozone except for large areas of the lower stratosphere, where no significant changes or even decreases in the ozone concentration are found. For a better understanding of the importance of (A) emissions like NO{sub x} and CFCs, (B) future changes of air temperature and water vapour concentration, and (C) other dynamic parameters, like precipitation and changes in the circulation, i.e. wind speed, diabatic circulation, stratosphere-troposphere-exchange, the simulation of the future atmosphere has been performed stepwise. This method requires a climate-chemistry model without interactive coupling of chemical species. Model results show that the direct effect of emissions (A) plays a major role for the composition of the future atmosphere, but they also clearly show that climate change has a significant impact and strongly reduces the NO{sub y} and ozone concentration in the lower stratosphere. (orig.)

  8. Atmospheric composition change research: Time to go post-normal?

    DEFF Research Database (Denmark)

    Guimaraes Pereira, Angela; Raes, Frank; De Sousa Pedrosa, Tiago

    2009-01-01

    Formore than two decades a number of frameworks for scientific knowledge production are being proposed by science and technology researchers. They all advocate an extended involvement of non-specialists, in particularwhen it comes to knowledge production applicable to practical societal problems.......We look towhat extent these new frameworks have taken ground within a particular research community: the ACCENT Network of Excellence which coordinates European atmospheric chemistry and physics research applicable to air pollution and climate change.We did so by stimulating a debate through a ‘‘blog......’’, a survey and in-depth interviews with ACCENT scientists about the interaction between science, policy making and civil society, to which a great deal of ACCENTmember contributed inwriting or verbally.Most of themhad interactions with policy makers and/or the general public, and they generally believe...

  9. Mirador - Atmospheric Composition

    Data.gov (United States)

    National Aeronautics and Space Administration — Earth Science data access made simple. Atmospheric Composition is focused on the composition of Earth's atmosphere in relation to climate prediction, solar effects,...

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

    Science.gov (United States)

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

    2016-07-01

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

  11. Response of the global climate to changes in atmospheric chemical composition due to fossil fuel burning

    Science.gov (United States)

    Hameed, S.; Cess, R. D.; Hogan, J. S.

    1980-01-01

    Recent modeling of atmospheric chemical processes (Logan et al, 1978; Hameed et al, 1979) suggests that tropospheric ozone and methane might significantly increase in the future as the result of increasing anthropogenic emissions of CO, NO(x), and CH4 due to fossil fuel burning. Since O3 and CH4 are both greenhouse gases, increases in their concentrations could augment global warming due to larger future amounts of atmospheric CO2. To test the possible climatic impact of changes in tropospheric chemical composition, a zonal energy-balance climate model has been combined with a vertically averaged tropospheric chemical model. The latter model includes all relevant chemical reactions which affect species derived from H2O, O2, CH4, and NO(x). The climate model correspondingly incorporates changes in the infrared heating of the surface-troposphere system resulting from chemically induced changes in tropospheric ozone and methane. This coupled climate-chemical model indicates that global climate is sensitive to changes in emissions of CO, NO(x) and CH4, and that future increases in these emissions could augment global warming due to increasing atmospheric CO2.

  12. Recent and predicted changes in atmospheric composition over the United States from climate, emissions, and pine beetles

    Science.gov (United States)

    Heald, C. L.; Berg, A.; Val Martin, M.; Meddens, A. J.; Hicke, J. A.; Huff Hartz, K. E.; Lamarque, J.; Tilmes, S.; Emmons, L. K.

    2012-12-01

    Changes in emissions, climate and land use all play a key role in modulating the composition of the troposphere. In this talk I will cover two topics related to this theme. First, to examine the relative impacts of these effects, I will discuss predicted changes in air quality (PM and ozone) by 2050 over the United States following the latest RCP scenarios in the Community Earth System Model. Second, as an example of climate-biosphere-atmosphere interactions, I will discuss the impact of the recent mountain pine beetle outbreak on VOC emissions and organic aerosol concentrations in Western North America over the last decade.

  13. Electron spectroscopic analysis of the human lipid skin barrier: cold atmospheric plasma-induced changes in lipid composition.

    Science.gov (United States)

    Marschewski, Marcel; Hirschberg, Joanna; Omairi, Tarek; Höfft, Oliver; Viöl, Wolfgang; Emmert, Steffen; Maus-Friedrichs, Wolfgang

    2012-12-01

    The lipids of the stratum corneum comprise the most important components of the skin barrier. In patients with ichthyoses or atopic dermatitis, the composition of the skin barrier lipids is disturbed resulting in dry, scaly, itching erythematous skin. Using the latest X-Ray Photoelectron Spectroscopy (XPS) technology, we investigated the physiological skin lipid composition of human skin and the effects of cold atmospheric plasma treatment on the lipid composition. Skin lipids were stripped off forearms of six healthy volunteers using the cyanoacrylate glue technique, plasma treated or not and then subjected to detailed XPS analysis. We found that the human lipid skin barrier consisted of 84.4% carbon (+1.3 SEM%), 10.8% oxygen (+1.0 SEM%) and 4.8% nitrogen (+0.3 SEM%). The composition of physiological skin lipids was not different in males and females. Plasma treatment resulted in significant changes in skin barrier lipid stoichiometry. The total carbon amount was reduced to 76.7%, and the oxygen amount increased to 16.5%. There was also a slight increase in nitrogen to 6.8%. These changes could be attributed to reduced C-C bonds and increased C-O, C=O, C-N and N-C-O bonds. The moderate increase in nitrogen was caused by an increase in C-N and N-C-O bonds. Our results show for the first time that plasma treatment leads to considerable changes in the human skin lipid barrier. Our proof of principle investigations established the technical means to analyse, if plasma-induced skin lipid barrier changes may be beneficial in the treatment of ichthyotic or eczematous skin.

  14. Changes in atmospheric composition during the 2014 APEC conference in Beijing

    Science.gov (United States)

    Wang, Zhanshan; Li, Yunting; Chen, Tian; Li, Lingjun; Liu, Baoxian; Zhang, Dawei; Sun, Feng; Wei, Qiang; Jiang, Lei; Pan, Libo

    2015-12-01

    Five sites were selected to investigate the impact of regional-scale air pollutant control strategies during the Asia-Pacific Economic Cooperation (APEC) conference (1-12 November 2014) in and around Beijing. Concentrations of most of the air pollutants in the APEC period were significantly lower than those in the adjacent time period, especially when the enhanced reduction measures were implemented. Compared with the same time period in the previous 5 years (PM2.5 was compared with the last year), average concentrations of SO2, NO2, PM10, and PM2.5 in the five sites during the APEC period decreased by 62%, 41%, 36%, and 47% respectively, whereas average concentration of O3 increased by 102%. A possible cause of the increase of O3 concentrations is the stricter reduction measure on NOx compared to that applied to volatile organic compounds. Compared with the non-APEC period in autumn 2014, concentrations of most of the chemical compositions of PM2.5 decreased significantly in the APEC period, especially SO42-, NO3-, and NH4+ (sulfate, nitrate, and ammonium). The aerosol optical depth and the columnar NO2 in the area of 39.5°-40.5°N, 116°-117°E showed a changing pattern similar to the typical gas pattern. The net effectiveness of the emission reduction measures was calculated through a comparison of concentrations of air pollutants under similar meteorological conditions. Through the reduction measures imposed during the APEC period, concentrations of CO, SO2, NO, NO2, PM10, and PM2.5 decreased by 54%, 74%, 64%, 48%, 67%, and 65%, respectively, whereas concentrations of O3 increased by 189%.

  15. Modeling the Changing Chemical Composition of the Atmosphere: Impacts from the Stratosphere, Transport Modes and Climate Variability

    Science.gov (United States)

    Grewe, V.; Obermaier, K.; Ponater, M.; Matthes, S.

    2008-12-01

    The chemical composition of the atmosphere is permanently changing, driven by changes in emissions (natural and anthropogenic) as well as natural climate variability (e.g. El Nino, stratospheric variability). Here, an ensemble climate chemistry simulation for the period 1960 to 2020 is presented in which stratospheric and tropospheric chemistry are regarded consistently (Dameris et al., 2005; Grewe, 2007). Changes in chemistry and radiative forcing are analysed in detail. The results show: a reduced tropospheric ozone increase in the 90s caused by a decrease of stratospheric ozone influxes due to stratospheric ozone depletion. a reduced tropospheric ozone column in the equatorial pacific region due to El Nino (in agreement with observations), however an increase in lightning and related tropospheric ozone. a peak in ozone production efficiency due to NOx emission in around 1990 decrease in lightning NOx emissions over the whole period due to less (though stronger) convective events. differences between the radiative efficiency of tropospheric ozone changes contributed by individual sources changes of the radiative efficiency of the same source throughout the 60-yr period Grewe, V., Impact of climate variability on tropospheric ozone, Science of The Total Environment, 374, 167- 181, 2007. Dameris, M., Grewe, V., Ponater, M., "., Long-term changes and variability in a transient simulation with a chemistry-climate model employing realistic forcing, ACP 5, 2121-2145, 2005.

  16. A global model study of the impact of land-use change in Borneo on atmospheric composition

    Directory of Open Access Journals (Sweden)

    N. J. Warwick

    2013-09-01

    Full Text Available In this study, a high resolution version of the Cambridge p-TOMCAT chemical transport model is used, along with measurement data from the 2008 NERC-funded Oxidant and Particle Photochemical Processes (OP3 project, to examine the potential impact of the expansion of oil palm in Borneo on atmospheric composition. Several model emission scenarios are run for the OP3 measurement period, incorporating emissions from both global datasets and local flux measurements. Using the OP3 observed isoprene fluxes and OH recycling chemistry in p-TOMCAT substantially improves the comparison between modelled and observed isoprene and OH concentrations relative to using MEGAN isoprene emissions without OH recycling. However, a similar improvement was also achieved without using HOx recycling, by fixing boundary layer isoprene concentrations over Borneo to follow the OP3 observations. An extreme hypothetical future scenario, in which all of Borneo is converted to oil palm plantation, assessed the sensitivity of the model to changes in isoprene and NOx emissions associated with land-use change. This scenario suggested a 70% upper limit on surface ozone increases resulting from land-use change on Borneo, excluding the impact of future changes in emissions elsewhere. Although the largest changes in this scenario occurred directly over Borneo, the model also calculated notable regional changes of O3, OH and other species downwind of Borneo and in the free troposphere.

  17. A study of the impact of land-use change in Borneo on atmospheric composition using a global model

    Directory of Open Access Journals (Sweden)

    N. J. Warwick

    2013-03-01

    Full Text Available In this study, we use a high resolution version of the Cambridge p-TOMCAT model, along with data collected during the 2008 NERC-funded Oxidant and Particle Photochemical Processes (OP3 project, to examine the potential impact of the expansion of oil palm in Borneo on air quality and atmospheric composition. Several model emission scenarios are run for the OP3 measurement period, incorporating emissions from both global datasets and local flux measurements. Isoprene fluxes observed at a forest site during OP3 were considerably less than fluxes calculated using the MEGAN model. Incorporating the observed isoprene fluxes into p-TOMCAT substantially improved the comparison between modelled and observed isoprene surface mixing ratios and OH concentrations relative to using the MEGAN emissions. If both observed isoprene fluxes and HOx recycling chemistry were included, the ability of the model to capture diurnal variations in isoprene and OH was further improved. However, a similar improvement was also achieved using a~standard chemical mechanism without HOx recycling, by fixing boundary layer isoprene concentrations over Borneo to follow the OP3 observations. Further model simulations, considering an extreme scenario with all of Borneo converted to oil palm plantation, were run to determine the maximum atmospheric impact of land use change in Borneo. In these simulations, the level of nitrogen oxides was found to be critical. If only isoprene emissions from oil palm are considered, then large scale conversion to oil palm produced a decrease in monthly mean surface ozone of up to ~20%. However, if related changes in NOx emissions from fertilisation, industrial processing and transport are also included then ozone increases of up to ~70% were calculated. Although the largest changes occurred locally, the model also calculated significant regional changes of O3, OH and other species downwind of Borneo and in the free troposphere.

  18. Changes in fungal community composition in response to elevated atmospheric CO2 and nitrogen fertilization varies with soil horizon

    Directory of Open Access Journals (Sweden)

    Carolyn F Weber

    2013-04-01

    Full Text Available Increasing levels of atmospheric carbon dioxide (CO2 and rates of nitrogen (N-deposition to forest ecosystems are predicted to alter the structure and function of soil fungal communities, but the spatially heterogeneous distribution of soil fungi has hampered investigations aimed at understanding such impacts. We hypothesized that soil physical and chemical properties and fungal community composition would be differentially impacted by elevated atmospheric CO2 (eCO2 and N-fertilization in spatially separated field samples, in the forest floor, 0-2 cm, 2-5 cm and 5-10 cm depth intervals in a loblolly pine Free-Air-Carbon Dioxide Enrichment (FACE experiment. In all soils, quantitative PCR-based estimates of fungal biomass were highest in the forest floor. Fungal richness, based on pyrosequencing of the fungal ribosomal large subunit gene, increased in response to N-fertilization in 0-2 cm and forest floor intervals. Composition shifted in forest floor, 0-2 cm and 2-5 cm intervals in response to N-fertilization, but the shift was most distinct in the 0-2 cm interval, in which the largest number of statistically significant changes in soil chemical parameters (i.e phosphorus, organic matter, calcium, pH was also observed. In the 0-2 cm interval, increased recovery of sequences from the Thelephoraceae, Tricholomataceae, Hypocreaceae, Clavicipitaceae, and Herpotrichiellaceae families and decreased recovery of sequences from the Amanitaceae correlated with N-fertilization. In this same depth interval, Amanitaceae, Tricholomataceae and Herpotriciellaceae sequences were recovered less frequently from soils exposed to eCO2 relative to ambient conditions. These results demonstrated that vertical stratification should be taken into consideration in future efforts to elucidate environmental impacts on fungal communities and their feedbacks on ecosystem processes.

  19. SOME RESULTS OF UPPER ATMOSPHERIC COMPOSITION MEASUREMENTS BY A MASS-SPECTROMETER ON BOARD "SZ-2":CHANGE OF COMPOSITIONS DURING SOLAR AND GEOMAGNETIC DISTURBANCES

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Upper atmosphere composition data were obtained for the last half year with a quadruple mass spectrometer on board spacecraft "SZ-2" launched on 10 Jan uary 2001. Based on the analysis of these data, the variations of atmospheric compositions in solar and geomagnetic quiet conditions are reported first, then a detailed discussion on the atmospheric composition variations under the so lar and geomagnetic disturbed conditions is given. The results show that near the altitude of 400 km the variations of main atmospheric compositions corre sponding to solar disturbances are more remarkable in the sunlit area than in the shade area. On the contrary, in geomagnetic disturbance events the corre sponding variations are more obvious in the shade area, an evident increase of N2 density at relatively higher latitudes was observed.

  20. Multi-element composition of historical lichen collections and bark samples, indicators of changing atmospheric conditions

    Science.gov (United States)

    Purvis, O. W.; Chimonides, P. D. J.; Jeffries, T. E.; Jones, G. C.; Rusu, A.-M.; Read, H.

    Thirty six element signatures were compared in historical Parmelia sulcata samples from the Natural History Museum herbarium collected over the period 1797-1967 with those recorded in the same species and tree bark sampled in 2000 from Burnham Beeches, lying 40 km west of London. Nineteen elements reached highest concentrations in herbarium samples, consistent with a pollution legacy and dust contamination in the herbarium. Healthy Parmelia sampled east and down-wind of London at a farm during peak SO 2 emissions in 1967 contained highest V, Ni, Zn, Cd, Se, Ge contents, supporting derivation from fuel combustion; the same sample was previously determined as having a low δ34S and high S and N contents. Lowest V, Co, Ni, Cu, Zn, Sn, Ba, Pb, Mo, Sb, Li, B, Cs, U, Th, Ga contents were recorded in a sample with a high δ34S and low S content collected in 1887 from a remote region from Ross-shire, Scotland. Se and Cd enrichment, never-the-less suggest a transboundary pollution influence. Lichen Pb concentrations from Burnham Beeches were amongst the lowest recorded in spite of lichens being collected close to roads. Herbarium samples help interpret changes in element deposition where few data exist, in spite of dust contamination.

  1. The Influence of 21st Century Climate Change on the Isotopic Composition of Atmospheric Moisture and How it Relates to Past Hydrological Changes

    Science.gov (United States)

    Buenning, N. H.; Stott, L. D.; Yoshimura, K.

    2014-12-01

    Increases in greenhouse gas concentrations through the 21st century are projected to increase global temperatures and change circulation and precipitation patterns globally. However, there remain many uncertainties in how the general circulation of the atmosphere will change and how it will impact regional hydroclimates. In the low and middle latitudes the isotopic composition (δ) of atmospheric moisture could potentially be useful at tracing these changes in precipitation and wind patterns. In this study sea surface temperatures and sea ice conditions from 21st century climate projections (RCP8.5 scenario) were used to force the isotope-enabled Global Spectral Model (IsoGSM). This ensemble of IsoGSM simulations provides insight as to how and where water isotopologues will change globally as a result of 21st century climate change. In general, δ values increase in the subtropics and middle latitudes and decrease in the southern tropics. Changes to horizontal winds suggest that the isotopic changes are likely due to changes in the strength of the Hadley Cell, rather than the poleward expansion of the descending branch of the cells. Regionally, the simulations project consistent increases in δ values through the 21st century over central and southern Africa, the Tibetan Plateau, and the eastern Australia. Decreasing δ values were found over the eastern tropical Pacific and the western margins of South America. A comparison with a present-day IsoGSM simulation reveals similar regional changes in δ values over the last 60 years. The similarities between recent changes and 21st century projections of δ values suggest that certain hydrological aspects of 21st century climate change are already taking place in some regions. Central Africa stands out as a region where IsoGSM simulates robust rises in precipitation and vapor δ values for both the 21st century and the late 20th century. The recent rise in δ values over central Africa is validated against

  2. Introduction to the European Monitoring and Evaluation Programme (EMEP and observed atmospheric composition change during 1972–2009

    Directory of Open Access Journals (Sweden)

    K. E. Yttri

    2012-01-01

    Full Text Available European scale harmonized monitoring of atmospheric composition was initiated in the early 1970ies, and the activity has generated a comprehensive dataset which allows to evaluate regional and spatial trends of air pollution during a period of nearly 40 yr. Results from the monitoring made within EMEP, the European Monitoring and Evaluation Programme, show large reductions in ambient concentrations and deposition of sulphur species during the last decades. Reductions are in the order of 70–90% since the year 1980, and correspond well with reported emission changes. Also reduction in emissions of nitrogen oxides (NOx are reflected in the measurements, with an average decrease of nitrogen dioxide and nitrate in precipitation by about 23% and 25% respectively since 1990. Only minor reductions are however seen since the late 1990ies. The concentrations of total nitrate in air have decreased on average only by 8% since 1990, and fewer sites show a significant trend. A majority of the EMEP sites show a decreasing trend in reduced nitrogen both in air and precipitation on the order of 25%. Deposition of base cations has decreased during the past 30 yr, and the pH in precipitation has increased across Europe. Large interannual variations in the particulate matter mass concentrations reflect meteorological variability, but still there is a relatively clear overall decrease at several sites during the last decade. With few observations going back to the 1990ies, the observed chemical composition is applied to document a change in particulate matter (PM mass even since 1980. These data indicate an overall reduction of about 5 μg m−3 from sulphate alone. Long-term ozone trends at EMEP sites show a mixed pattern. The year-to-year variability in ozone due to varying meteorology is substantial, making it hard to separate the trends caused by reduced emissions from other effects. For the Nordic countries the data indicate a slight reduction in the number

  3. Carbon balance in conterminous U.S. forests based on historic changes in climate, atmospheric composition, and disturbances

    Science.gov (United States)

    Zhang, F.; Chen, J.; Ju, W.; Shen, S.; Pan, Y.; Birdsey, R.; He, L.

    2010-12-01

    Forest ecosystems are the dominant contributors to the carbon sink in terrestrial ecosystems. Although many studies have already explored the effects of non-disturbance factors such as climate and atmospheric composition on the terrestrial carbon cycle, few studies have systematically considered the impact of disturbance on the forest carbon cycle at regional scale, mostly because of the lack of spatially and temporally explicit disturbance data. In this study, we show, for the first time, the spatio-temporal distribution of the carbon sink in conterminous U.S. forests from 1901 to 2006 modeled with the consideration of both disturbance and non-disturbance effects using the Integrated Terrestrial Ecosystem Carbon Model (InTEC). The application of this model is possible owing to the recently available national forest age data in 2000. Our results show that the annual net primary productivity of conterminous U.S. forests increased from 1476 Tg C yr-1 in the early 20th century to 1892 Tg C yr-1 in the early 21st century, whereas the net biome productivity increased from -32.9 Tg C yr-1 to 422.5 Tg C yr-1 in the same period. The overall results indicate that forest sink extended from North regions to South and Southeast regions and the maximum sink occurred in the Kentucky and Tennesee states after 1990. Fig. 1. (a-c) Carbon (C) dynamics of the conterminous U.S. forests over last 106 years from 1901 to 2006 (a-c); (d-f) Spatial distribution of carbon sources/sinks in the forest ecosystems of the conterminous U.S. in the 1980s, 1990s and 2000s. Table 1 Changes of carbon storages of forest ecosystem in different regions of the conterminous U.S. over last 106 years from 1901 to 2006 (Unit: Tg C yr-1). (1) Northeast (NE); (2) Northern Lake (NL); (3) North Plain (NP); (4) Pacific Northwest (PN); (5) Pacific Southwest (PS); (6) Rocky Mountain North (RMN); (7) Rocky Mountain South (RMS); (8) South Central (SC); (9) Southeast (SE).

  4. Atmospheric Chemistry in a Changing World

    Science.gov (United States)

    Brune, William H.

    The world is changing,and the atmosphere's composition is changing with it. Human activity is responsible for much of this. Global population growth and migration to urban centers, extensive biomass burning, the spread of fertilizer-intensive agribusiness, globalization of business and industry, rising standards of living in the developing world, and increased energy use fuels atmospheric change. If current practices continue, atmospheric increases are likely for the greenhouse gases carbon dioxide, methane, nitrous oxide; and for the chemically active gases nitric oxide, sulfur dioxide,and ammonia. Increases in global tropospheric ozone and aerosols are a distinct possibility.

  5. Global atmospheric changes.

    OpenAIRE

    Piver, W T

    1991-01-01

    Increasing concentrations of CO2 and other greenhouse gases in the atmosphere can be directly related to global warming. In terms of human health, because a major cause of increasing atmospheric concentrations of CO2 is the increased combustion of fossil fuels, global warming also may result in increases in air pollutants, acid deposition, and exposure to ultraviolet (UV) radiation. To understand better the impacts of global warming phenomena on human health, this review emphasizes the proces...

  6. Temperature response of the troposphere and stratosphere to changes in gas and aerosol composition of the atmosphere

    Science.gov (United States)

    Dyominov, I. G.; Zadorozhny, A. M.; Elansky, N. F.

    2003-04-01

    A numerical 2-D zonally averaged interactive model of the troposphere and stratosphere including aerosol physics is used for investigation of temperature changes caused by discharges to the atmosphere of sulphate species during the Pinatubo eruption and by anthropogenic pollution of the atmosphere by CO_2, CH_4, N_2O, CFCs, HCFCs, HFCs, CH_3CCl_3 and CCl_4. The model calculates self-consistently diabatic circulation, temperature, distributions of 45 minor gas constituents, and condensed particles of sulphuric acid hydrate with radii 6.4 nm discharges of sulphate species to the atmosphere during the Pinatubo eruption led to significant changes of sulfate aerosol layer, ozone, and temperature regime of the troposphere and stratosphere. For example, we have in tropics (20oS-20oN) a temperature increase of bout 2.5-3.5 K at altitudes of 22-24 km and decrease of about 0.8-1.0 K at altitudes of 5-8 km. Discharges of sulphate species from the Pinatubo eruption significantly increased also the aerosol optical thickness of the stratosphere, which led to an about 0.3 K decrease in monthly mean global temperature at the Earth's surface by the end of 1992. The calculations of the long-term temperature variations due to anthropogenic emission show that the greatest temperature changes are observed in the Southern Hemisphere in winter/spring periods. For example, the temperature changes at a height of 40 km at 45oS in December 2050 are about -4.85 K, 0.89 K, -2.21 K, and -4.32 K respectively for anthropogenic discharges of CO_2, CH_4, N_2O, and chlorine species. The changes in the Northern Hemisphere are smaller. They are equal to about -4.5 K, 0.68 K, -1.46 K, and -3.17 K at 45oN. The temperature changes in the stratosphere are caused by the corresponding ozone variations and temperature feedbacks. In the troposphere, the temperature changes are determined by the greenhouse effect caused by optically active pollutants. For example, temperature increases near the Earth's surface

  7. Changes in elemental composition and mass of atmospheric aerosol pollution between 1996 and 2002 in a Central European city

    Energy Technology Data Exchange (ETDEWEB)

    Salma, Imre [Environmental Chemistry, Eoetvoes University, P.O. Box 32, H-1518 Budapest (Hungary)]. E-mail: salma@para.chem.elte.hu; Maenhaut, Willy [Institute for Nuclear Sciences, Ghent University, Proeftuinstraat 86, B-9000 Ghent (Belgium)

    2006-10-15

    Median atmospheric concentrations of Pb, Br, S, As, Se, and particulate matter (PM) decreased, and median concentrations of Sb, Cu, Zn, Fe, Ca, Cr and Ba increased in urban aerosol in downtown Budapest between 1996 and 2002. The changes in Pb and Br concentrations were unambiguously attributed to the phasing out of leaded gasoline. The increments were mainly related to and explained by non-exhaust vehicular emissions. The mechanical wear of asbestos-free brake linings of road vehicles contributed to the concentration of Cu and Sb on average by 69% and 66%, respectively in the PM10 size fraction. Tire rubber abrasion was a major source for atmospheric Zn; on average, non-crustal sources accounted for 67% of Zn in the PM10 size fraction. Contribution of the tire wear component to the PM10 mass was estimated to be 6% at most, while its contribution to organic aerosol was of the order of 15%. - Non-exhaust traffic emission particles and coarse-mode particles are increasing in Budapest, Hungary.

  8. Impacts of Ozone-vegetation Interactions and Biogeochemical Feedbacks on Atmospheric Composition and Air Quality Under Climate Change

    Science.gov (United States)

    Sadeke, M.; Tai, A. P. K.; Lombardozzi, D.; Val Martin, M.

    2015-12-01

    Surface ozone pollution is one of the major environmental concerns due to its damaging effects on human and vegetation. One of the largest uncertainties of future surface ozone prediction comes from its interaction with vegetation under a changing climate. Ozone can be modulated by vegetation through, e.g., biogenic emissions, dry deposition and transpiration. These processes are in turn affected by chronic exposure to ozone via lowered photosynthesis rate and stomatal conductance. Both ozone and vegetation growth are expected to be altered by climate change. To better understand these climate-ozone-vegetation interactions and possible feedbacks on ozone itself via vegetation, we implement an online ozone-vegetation scheme [Lombardozzi et al., 2015] into the Community Earth System Model (CESM) with active atmospheric chemistry, climate and land surface components. Previous overestimation of surface ozone in eastern US, Canada and Europe is shown to be reduced by >8 ppb, reflecting improved model-observation comparison. Simulated surface ozone is lower by 3.7 ppb on average globally. Such reductions (and improvements) in simulated ozone are caused mainly by lower isoprene emission arising from reduced leaf area index in response to chronic ozone exposure. Effects via transpiration are also potentially significant but require better characterization. Such findings suggest that ozone-vegetation interaction may substantially alter future ozone simulations, especially under changing climate and ambient CO2 levels, which would further modulate ozone-vegetation interactions. Inclusion of such interactions in Earth system models is thus necessary to give more realistic estimation and prediction of surface ozone. This is crucial for better policy formulation regarding air quality, land use and climate change mitigation. Reference list: Lombardozzi, D., et al. "The Influence of Chronic Ozone Exposure on Global Carbon and Water Cycles." Journal of Climate 28.1 (2015): 292-305.

  9. Detection of Atmospheric Composition Based on Lidar

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Jinye; Tong Yala; Yang Xiaoling; Gong Jiaoli [School of science, Hubei University of Technology, Wuhan 430068 (China); Gong Wei, E-mail: yezi.zh@163.com [State Key Laboratory for Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430079 (China)

    2011-02-01

    A summary overview about the types of lidar and their own applications on atmosphere detection is presented. Measurement of atmospheric aerosols by Mie lidar and Raman lidar is focused. The vertical profiles of aerosols in the atmosphere are retrieved. And at the same time, through analyzing aerosol vertical content distribution, the atmosphere boundary layer and the cloud are also observed. All the results show that the lidar has good performance on detecting the atmospheric composition.

  10. Atmospheric composition forecasting in Europe

    Directory of Open Access Journals (Sweden)

    L. Menut

    2010-01-01

    Full Text Available The atmospheric composition is a societal issue and, following new European directives, its forecast is now recommended to quantify the air quality. It concerns both gaseous and particles species, identified as potential problems for health. In Europe, numerical systems providing daily air quality forecasts are numerous and, mostly, operated by universities. Following recent European research projects (GEMS, PROMOTE, an organization of the air quality forecast is currently under development. But for the moment, many platforms exist, each of them with strengths and weaknesses. This overview paper presents all existing systems in Europe and try to identify the main remaining gaps in the air quality forecast knowledge. As modeling systems are now able to reasonably forecast gaseous species, and in a lesser extent aerosols, the future directions would concern the use of these systems with ensemble approaches and satellite data assimilation. If numerous improvements were recently done on emissions and chemistry knowledge, improvements are still needed especially concerning meteorology, which remains a weak point of forecast systems. Future directions will also concern the use of these forecast tools to better understand and quantify the air pollution impact on health.

  11. Atmospheric changes from solar eclipses.

    Science.gov (United States)

    Aplin, K L; Scott, C J; Gray, S L

    2016-09-28

    This article reviews atmospheric changes associated with 44 solar eclipses, beginning with the first quantitative results available, from 1834 (earlier qualitative accounts also exist). Eclipse meteorology attracted relatively few publications until the total solar eclipse of 16 February 1980, with the 11 August 1999 eclipse producing the most papers. Eclipses passing over populated areas such as Europe, China and India now regularly attract scientific attention, whereas atmospheric measurements of eclipses at remote locations remain rare. Many measurements and models have been used to exploit the uniquely predictable solar forcing provided by an eclipse. In this paper, we compile the available publications and review a subset of them chosen on the basis of importance and novelty. Beyond the obvious reduction in incoming solar radiation, atmospheric cooling from eclipses can induce dynamical changes. Observations and meteorological modelling provide evidence for the generation of a local eclipse circulation that may be the origin of the 'eclipse wind'. Gravity waves set up by the eclipse can, in principle, be detected as atmospheric pressure fluctuations, though theoretical predictions are limited, and many of the data are inconclusive. Eclipse events providing important early insights into the ionization of the upper atmosphere are also briefly reviewed.This article is part of the themed issue 'Atmospheric effects of solar eclipses stimulated by the 2015 UK eclipse'.

  12. Composition changes after the "Halloween" solar proton event: the High Energy Particle Precipitation in the Atmosphere (HEPPA model versus MIPAS data intercomparison study

    Directory of Open Access Journals (Sweden)

    B. Funke

    2011-09-01

    Full Text Available We have compared composition changes of NO, NO2, H2O2, O3, N2O, HNO3, N2O5, HNO4, ClO, HOCl, and ClONO2 as observed by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS on Envisat in the aftermath of the "Halloween" solar proton event (SPE in late October 2003 at 25–0.01 hPa in the Northern Hemisphere (40–90° N and simulations performed by the following atmospheric models: the Bremen 2-D model (B2dM and Bremen 3-D Chemical Transport Model (B3dCTM, the Central Aerological Observatory (CAO model, FinROSE, the Hamburg Model of the Neutral and Ionized Atmosphere (HAMMONIA, the Karlsruhe Simulation Model of the Middle Atmosphere (KASIMA, the ECHAM5/MESSy Atmospheric Chemistry (EMAC model, the modeling tool for SOlar Climate Ozone Links studies (SOCOL and SOCOLi, and the Whole Atmosphere Community Climate Model (WACCM4. The large number of participating models allowed for an evaluation of the overall ability of atmospheric models to reproduce observed atmospheric perturbations generated by SPEs, particularly with respect to NOy and ozone changes. We have further assessed the meteorological conditions and their implications for the chemical response to the SPE in both the models and observations by comparing temperature and tracer (CH4 and CO fields.

    Simulated SPE-induced ozone losses agree on average within 5 % with the observations. Simulated NOy enhancements around 1 hPa, however, are typically 30 % higher than indicated by the observations which are likely to be related to deficiencies in the used ionization rates, though other error sources related to the models' atmospheric background state and/or transport schemes cannot be excluded. The analysis of the observed and modeled NOy partitioning in the aftermath of the SPE has demonstrated the need to implement

  13. Atmospheric changes from solar eclipses

    CERN Document Server

    Aplin, Karen; Gray, Suzanne

    2016-01-01

    This article reviews atmospheric changes associated with 44 solar eclipses, beginning with the first quantitative results available, from 1834 (earlier qualitative, accounts also exist). Eclipse meteorology attracted relatively few publications until the total solar eclipse of 16 February 1980, with the 11 August 1999 eclipse producing the most papers. Eclipses passing over populated areas such as Europe, China and India now regularly attract scientific attention, whereas atmospheric measurements of eclipses at remote locations remain rare. Many measurements and models have been used to exploit the uniquely predictable solar forcing provided by an eclipse. In this paper we compile the available publications and review a sub-set of them chosen on the basis of importance and novelty. Beyond the obvious reduction in incoming solar radiation, atmospheric cooling from eclipses can induce dynamical changes. Observations and meteorological modelling provide evidence for the generation of a local eclipse circulation ...

  14. Composition changes after the "Halloween" solar proton event: the High-Energy Particle Precipitation in the Atmosphere (HEPPA model versus MIPAS data intercomparison study

    Directory of Open Access Journals (Sweden)

    B. Funke

    2011-03-01

    Full Text Available We have compared composition changes of NO, NO2, H2O2, O3, N2O, HNO3, N2O5, HNO4, ClO, HOCl, and ClONO2 as observed by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS on Envisat in the aftermath of the "Halloween" solar proton event (SPE in October/November 2003 at 25–0.01 hPa in the Northern Hemisphere (40–90° N and simulations performed by the following atmospheric models: the Bremen 2d Model (B2dM and Bremen 3d Chemical Transport Model (B3dCTM, the Central Aerological Observatory (CAO model, FinROSE, the Hamburg Model of the Neutral and Ionized Atmosphere (HAMMONIA, the Karlsruhe Simulation Model of the Middle Atmosphere (KASIMA, the ECHAM5/MESSy Atmospheric Chemistry (EMAC model, the modeling tool for SOlar Climate Ozone Links studies (SOCOL and SOCOLi, and the Whole Atmosphere Community Climate Model (WACCM4. The large number of participating models allowed for an evaluation of the overall ability of atmospheric models to reproduce observed atmospheric perturbations generated by SPEs, particularly with respect to NOy and ozone changes. We have further assessed the meteorological conditions and their implications on the chemical response to the SPE in both the models and observations by comparing temperature and tracer (CH4 and CO fields.

    Simulated SPE-induced ozone losses agree on average within 5% with the observations. Simulated oy enhancements around 1 hPa, however, are typically 30% higher than indicated by the observations which can be partly attributed to an overestimation of simulated electron-induced ionization. The analysis of the observed and modeled NOy partitioning in the aftermath of the SPE has demonstrated the need to implement additional ion chemistry (HNO3 formation via ion-ion recombination and water cluster ions into the chemical

  15. Atmospheric nitrogen compounds: Occurrence, composition and deposition

    DEFF Research Database (Denmark)

    Nielsen, T.; Pilegaard, K.; Egeløv, A.H.;

    1996-01-01

    Traffic in cities and on highways is an important contributor to NOy atmospheric pollution in open areas. In this situation both the concentration and composition of NOy compounds show a wide variation and are dependent on meteorological and atmospheric chemical conditions. The proportion of NOz...

  16. Changes in concentration, composition and source contribution of atmospheric organic aerosols by shifting coal to natural gas in Urumqi

    Science.gov (United States)

    Ren, Yanqin; Wang, Gehui; Wu, Can; Wang, Jiayuan; Li, Jianjun; Zhang, Lu; Han, Yanni; Liu, Lang; Cao, Cong; Cao, Junji; He, Qing; Liu, Xinchun

    2017-01-01

    Size-segregated aerosols were collected in Urumqi, a megacity in northwest China, during two heating seasons, i.e., before (heating season І: January-March 2012) and after (heating season II: January-March 2014) the project "shifting coal to natural gas", and determined for n-alkanes, PAHs and oxygenated PAHs to investigate the impact of replacement of coal by natural gas on organic aerosols in the urban atmosphere. Our results showed that compared to those in heating season I concentrations of n-alkanes, PAHs and OPAHs decreased by 74%, 74% and 82% in heating season II, respectively. Source apportionment analysis suggested that coal combustion, traffic emission and biomass burning are the major sources of the determined organics during the heating seasons in Urumqi. Traffic emission is the main source for n-alkanes in the city. Coal combustion is the dominant source of PAHs and OPAHs in heating season І, but traffic emission becomes their major source in heating season ІI. Relative contributions of coal combustion to n-alkanes, PAHs and OPAHs in Urumqi decreased from 21 to 75% in heating season I to 4.0-21% in heating season II due to the replacement of coal with natural gas for house heating. Health risk assessment further indicated that compared with that in heating season I the number of lung cancer related to PAHs exposure in Urumqi decreased by 73% during heating season II due to the project implementation. Our results suggest that replacing coal by clean energy sources for house heating will significantly mitigate air pollution and improve human health in China.

  17. Long-term temperature variations in the stratosphere and troposphere caused by changes in gas and aerosol composition of the atmosphere

    Science.gov (United States)

    Dyominov, I.; Zadorozhny, A.

    A numerical 2-D zonally averaged interactive dynamical radiative-photochemical model of the troposphere and stratosphere including aerosol physics is used for investigation of long-term temperature changes caused by anthropogenic pollution of the atmosphere by CO2 , CH4, N2O, CFCs, HCFCs, HFCs, CH 3CCl 3 and CCl4 as well as by discharges to the atmosphere of sulphate species during the Pinatubo eruption. The model allows calculating self-consistently diabatic circulation, temperature, gaseous composition of the troposphere and stratosphere at latitudes from the South to North Poles, as well as distribution of sulphate aerosol particles and polar stratospheric clouds (PSCs) of types I and II. The scenarios of expected changes of the anthropogenic pollutants for the period from 1990 through 2050 are taken from Climate Change 1995. The calculations of the long-term temperature variations due to anthropogenic emission s show that the greatest temperature changes are observed in the Southern Hemisphere in winter/spring periods. For example, the temperature changes at a height of 40 km at 45°S in December 2050 are about -4.85 K, 0.89 K, -2.21 K, and -4.32 K respectively for anthropogenic discharges of CO2, CH4, N2O, and chlorine species. The changes in the Northern Hemisphere are smaller. They are equal to about -4.5 K, 0.68 K, -1.46 K, and -3.17 K at 45°N. The temperature changes in the stratosphere are caused by the corresponding ozone variations and temperature feedbacks. In the troposphere, the temperature changes are determined by the greenhouse effect caused by optically active pollutants. For example, temperature increases near the Earth's surface at 45 °N in December of 2050 due to anthropogenic discharges of CO2, CH4, N2O, and chlorine species are about 0.87 K, 0.19 K, 0.14 K, and 0.32 K, respectively. The calculations show that short -term megaton discharges of sulphate species to the atmosphere during the Pinatubo eruption led to significant long

  18. Mass Independent Fractionation of Sulphur Isotopes in Precambrian Sedimentary Rocks: Indicator for Changes in Atmospheric Composition and the Operation of the Global Sulphur Cycle

    Science.gov (United States)

    Peters, M.; Farquhar, J.; Strauss, H.

    2005-12-01

    Large mass independent fractionation (MIF) of sulphur isotopes in sedimentary rocks older than 2.3 Ga and the absence of this isotopic anomaly in younger rocks seem to be the consequence of a change in Earth's atmospheric composition from essentially oxygen-free or to oxygen-rich conditions. MIF is produced by photochemical reactions of volcanogenic sulphur dioxide with UV radiation in the absence of an ozone shield. The products of such processes are elemental sulphur with positive and sulphate with negative Δ33S values. Here we present isotope data (32S, 33S, 34S) for sedimentary pyrites from Archaean and Palaeoproterozoic rocks of the Kaapvaal Craton (South Africa), the Pilbara Craton (Australia) and the Greenland Shield (Isua Supercrustal Belt). Their ages range from 3.85 to 2.47 Ga. Large positive Δ33S values up to +9.13 ‰ in several Archaean units from the Kapvaal and Pilbara Cratons are attributed to low atmospheric oxygen at that time. Interestingly, very low Δ33S values between -0.28 and +0.57 ‰ appear to characterize the Witwatersrand succession of South Africa (3.0 Ga). This rather small MIF signature was previously detected in rocks of the same age in Western Australia (OHMOTO et al., 2005). The signature is interpreted as a global signal, which could be the consequence of a shielding effect induced by one or more atmospheric components. The most probable chemical compounds for this process are methane and carbon dioxide. Rocks of the Kameeldoorns Fm. (2.71 Ga), Kaapvaal Craton, display also low values between -0.46 and +0.33 ‰, which are consistent with the small (absent) MIF signal in rocks of the Hardey Fm. (2.76 Ga) of Western Australia (OHMOTO et al., 2005). Very low carbon isotope values between -51 and -40 ‰ in late Archaean kerogens (2.6 - 2.8 Ga) indicate a high concentration of methane in the atmosphere (PAVLOV et al., 2001). This high methane level could produce an organic haze, which absorbed most of the UV radiation and prevented

  19. Improved instrumental line shape monitoring for the ground-based, high-resolution FTIR spectrometers of the Network for the Detection of Atmospheric Composition Change

    Directory of Open Access Journals (Sweden)

    F. Hase

    2012-03-01

    Full Text Available We propose an improved monitoring scheme for the instrumental line shape (ILS of high-resolution, ground-based FTIR (Fourier Transform InfraRed spectrometers used for chemical monitoring of the atmosphere by the Network for Detection of Atmospheric Composition Change (NDACC. Good ILS knowledge is required for the analysis of the recorded mid-infrared spectra. The new method applies a sequence of measurements using different gas cells instead of a single calibration cell. Three cells are used: cell C1 is a refillable cell offering 200 mm path length and equipped with a pressure gauge (filled with 100 Pa N2O, cells C2 and C3 are sealed cells offering 75 mm path length. C2 is filled with 5 Pa of pure N2O. Cell C3 is filled with 16 Pa N2O in 200 hPa technical air, so provides pressure-broadened N2O lines. We demonstrate that an ILS retrieval using C1 improves significantly the sensitivity of the ILS retrieval over the current calibration cells used in the network, because this cell provides narrow fully saturated N2O lines. The N2O columns derived from C2 and C3 allow the performance of a highly valuable closure experiment: adopting the ILS retrieved from C1, the N2O columns of C2 and C3 are derived. Because N2O is an inert gas, both columns should be constant on long timescales. Apparent changes in the columns would immediately attract attention and indicate either inconsistent ILS results or instrumental problems of other origin. Two different cells are applied for the closure experiment, because the NDACC spectrometers observe both stratospheric and tropospheric gases: C2 mimics signatures of stratospheric gases, whereas C3 mimics signatures of tropospheric gases.

  20. Atmospheric Data Package for the Composite Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Napier, Bruce A.; Ramsdell, James V.

    2005-09-01

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

  1. Modeling the effects of atmospheric emissions on groundwater composition

    Energy Technology Data Exchange (ETDEWEB)

    Brown, T.J.

    1994-12-31

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

  2. First intercalibration of column-averaged methane from the Total Carbon Column Observing Network and the Network for the Detection of Atmospheric Composition Change

    Directory of Open Access Journals (Sweden)

    R. Sussmann

    2013-02-01

    Full Text Available We present the first intercalibration of dry-air column-averaged mole fractions of methane (XCH4 retrieved from solar Fourier transform infrared (FTIR measurements of the Network for the Detection of Atmospheric Composition Change (NDACC in the mid-infrared (MIR versus near-infrared (NIR soundings from the Total Carbon Column Observing Network (TCCON. The study uses multi-annual quasi-coincident MIR and NIR measurements from the stations Garmisch, Germany (47.48° N, 11.06° E, 743 m a.s.l., and Wollongong, Australia (34.41° S, 150.88° E, 30 m a.s.l..

    Direct comparison of the retrieved MIR and NIR XCH4 time series for Garmisch shows a quasi-periodic seasonal bias leading to a standard deviation (stdv of the difference time series (NIR–MIR of 7.2 ppb. After reducing time-dependent a priori impact by using realistic site- and time-dependent ACTM-simulated profiles as a common prior, the seasonal bias is reduced (stdv = 5.2 ppb. A linear fit to the MIR/NIR scatter plot of monthly means based on same-day coincidences does not show a y-intercept that is statistically different from zero, and the MIR/NIR intercalibration factor is found to be close to ideal within 2-σ uncertainty, i.e. 0.9996(8. The difference time series (NIR–MIR do not show a significant trend. The same basic findings hold for Wollongong. In particular an overall MIR/NIR intercalibration factor close to the ideal 1 is found within 2-σ uncertainty. At Wollongong the seasonal cycle of methane is less pronounced and corresponding smoothing errors are not as significant, enabling standard MIR and NIR retrievals to be used directly, without correction to a common a priori.

    Our results suggest that it is possible to set up a harmonized NDACC and TCCON XCH4 data set which can be exploited for joint trend studies, satellite validation, or the inverse modeling of sources and sinks.

  3. First intercalibration of column-averaged methane from the Total Carbon Column Observing Network and the Network for the Detection of Atmospheric Composition Change

    Directory of Open Access Journals (Sweden)

    F. Forster

    2012-02-01

    Full Text Available We present the intercalibration of dry-air column-averaged mole fractions of methane (XCH4 retrieved from solar FTIR measurements of the Network for the Detection of Atmospheric Composition Change (NDACC in the mid-infrared (MIR versus near-infrared (NIR soundings from the Total Carbon Column Observing Network (TCCON. The study uses multi-annual quasi-coincident MIR and NIR measurements from the stations Garmisch, Germany (47.48° N, 11.06° E, 743 m a.s.l. and Wollongong, Australia (34.41° S, 150.88° E, 30 m a.s.l..

    Direct comparison of the retrieved MIR and NIR time series shows a phase shift in XCH4 seasonality, i.e. a significant time-dependent bias leading to a standard deviation (stdv of the difference time series (NIR-MIR of 8.4 ppb. After eliminating differences in a prioris by using ACTM-simulated profiles as a common prior, the seasonalities of the (corrected MIR and NIR time series agree within the noise (stdv = 5.2 ppb for the difference time series. The difference time series (NIR-MIR do not show a significant trend. Therefore it is possible to use a simple scaling factor for the intercalibration without a time-dependent linear or seasonal component. Using the Garmisch and Wollongong data together, we obtain an overall calibration factor MIR/NIR = 0.9926(18. The individual calibration factors per station are 0.9940(14 for Garmisch and 0.9893(40 for Wollongong. They agree within their error bars with the overall calibration factor which can therefore be used for both stations.

    Our results suggest that after applying the proposed intercalibration concept to all stations performing both NIR and MIR measurements, it should be possible to obtain one refined overall intercalibration factor for the two networks. This would allow to set up a harmonized NDACC and TCCON XCH4 data set which can be exploited for joint trend studies, satellite validation, or the inverse modeling of sources and

  4. Measurement of Atmospheric Composition from Geostationary Platforms

    Science.gov (United States)

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

    2008-01-01

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

  5. Effects of eustatic sea-level change, ocean dynamics, and iron fertilization on atmospheric pCO2 and seawater composition over the last 130 000 years

    Science.gov (United States)

    Wallmann, K.; Schneider, B.; Sarnthein, M.

    2015-06-01

    We developed and employed an earth system model to explore the forcings of atmospheric pCO2 change and the chemical and isotopic evolution of seawater over the last glacial cycle. Concentrations of dissolved phosphorus, reactive nitrogen, molecular oxygen, dissolved inorganic carbon (DIC), total alkalinity (TA), 13C-DIC and 14C-DIC were calculated for 24 ocean boxes. The bi-directional water fluxes between these model boxes were derived from a 3-D circulation field of the modern ocean (Opa 8.2, NEMO) and tuned such that tracer distributions calculated by the box model were consistent with observational data from the modern ocean. To model the last 130 kyr, we employed records of past changes in sea-level, ocean circulation, and dust deposition. According to the model, about half of the glacial pCO2 drawdown may be attributed to marine regressions. The glacial sea-level low-stands implied steepened ocean margins, a reduced burial of particulate organic carbon, phosphorus, and neritic carbonate at the margin seafloor, a decline in benthic denitrification, and enhanced weathering of emerged shelf sediments. In turn, they led to a distinct rise in the standing stocks of DIC, TA, and nutrients in the global ocean, promoted the glacial sequestration of atmospheric CO2 in the ocean, and added 13C- and 14C-depleted DIC to the ocean as recorded in benthic foraminifera signals. The other half of the glacial drop in pCO2 was linked to reduced deep ocean dynamics, a shoaling of Atlantic meridional overturning circulation, and a rise in iron fertilization. The increased transit time of deep waters in the glacial ocean led to significant 14C depletions with respect to the atmosphere. The deglacial rapid and stepwise rise in atmospheric pCO2 was induced by upwelling both in the Southern Ocean and subarctic North Pacific and promoted by a drop in dust-borne iron discharge to the Southern Ocean. The deglacial sea-level rise led to a gradual decline in nutrient, DIC, and TA stocks

  6. ESA's atmospheric composition and dynamics mission

    Science.gov (United States)

    Fehr, Thorsten; Laur, Henri; Hoersch, Bianca; Ingmann, Paul; Wehr, Tobias; Langen, Joerg; Veihelmann, Ben

    For almost 15 years, ESA is providing atmospheric chemistry and composition information to the user community. In 1995, this commitment started with the GOME instrument on-board ERS-2. This mission was continued and extended with the GOMOS, MIPAS and SCIAMACHY instruments on-board of ENVISAT launched in 2002. ESA is prepared to continue Envisat through 2013 in the frame of the mission extension. To respond to GMES requirements, ESA develops the Sentinel 5 Precursor mission to be launched in 2014, to continue and improve the European measurement capabilities initiated with GOME and SCIAMACHY, and continued with EUMETSAT's GOME-2 and the Dutch OMI instrument on the NASA Aura platform. In addition the Sentinel 4 and 5 missions are prepared, further improving the monitoring capabilities with geostationary observation capabilities and continuing the Low Earth Orbit Sentinel 5 Precursor well beyond 2025. At the same time, ESA is preparing two atmospheric Earth Explorer Missions. With ADM-Aeolus, a novel lidar system for the retrieval of wind speed vectors from space is being developed and planned to be launched in 2012. EarthCARE will investigate the Clouds-Aerosol-radiation-interaction with a lidar, cloud radar (provided by JAXA), multi-spectral imager and broad band radiometric instruments collocated on one platform. A major goal is the development of synergistic retrievals exploiting information from different sensors in one algorithm. The mission is planned to start in 2014. In parallel the Phase A studies for the ESA Earth Explorer 7 are ongoing. One of the three candidate missions is PREMIER, an infrared limb-imaging spectrometer and millimetre-wave limb-sounder planned to be launched in 2016. In addition the call of ideas for the Earth Explorer 8 has been published and the corresponding Letters of Intend have been received, including a number of proposals for mission in the atmospheric composition and dynamics domain. At the same time, the access to ESA Third

  7. The Agia Marina Xyliatou Observatory: A remote supersite in Cyprus to monitor changes in the atmospheric composition of the Eastern Mediterranean and the Middle East

    Science.gov (United States)

    Sciare, Jean

    2016-04-01

    The Eastern Mediterranean and Middle East (EMME) region has been identified as one of the hot spot region in the world strongly influenced by climate changes impacts. This region is characterized by rapidly growing population with contrasting economic development, strong environmental gradients and climate extremes. However, long-term observations of the atmospheric constituents (gaseous and particulate) of the atmosphere at a remote site representative of EMME is still missing making difficult to assess current and future impacts on air quality, water resources and climate. In collaboration with the Department of Labour Inspection and in the frame of French research programs (ChArMEx and ENVI-Med "CyAr") and the EU H2020 "ACTRIS-2" (2015-2019) project, CyI and CNRS are putting unprecedented efforts to implement at a rural site of Cyprus (Agia Marina Xyliatou) a unique infrastructure to monitor key atmospheric species relevant to air quality and climate. A large set of real-time instrumentations is currently deployed to characterize reactive gases (incl. O3, CO, NOx, SO2, VOC), in-situ aerosol properties (mass, size distribution, light scatt./absorption/extinction coef. and chemistry) and as well as integrated optical properties (sunphotomer, solar flux). Through Transnational access (H2020 ACTRIS2), this station is offering to (non-)EU partners (Research, SMEs) a new atmospheric facility to monitor long range transported clean/polluted air masses from 3 different continents (Europe, Africa, Middle East) and investigate aerosol-cloud interactions through the use of UAV and a mountain site (Troodos, 1900m asl). We will present here an overview of this new research infrastructure and provide a first glance of key features observed from gas/aerosol measurements obtained in 2015

  8. Seasonal changes in Titan's middle-atmosphere chemistry and dynamics

    Science.gov (United States)

    Teanby, N. A.; Irwin, P. G. J.; Nixon, C. A.; de Kok, R.; Vinatier, S.; Coustenis, A.; Sefton-Nash, E.; Calcutt, S. B.; Flasar, F. M.

    2013-09-01

    Titan is the largest satellite of Saturn and is the only moon in our solar system with a significant atmo- sphere. Titan's middle-atmosphere (stratosphere and mesosphere) circulation usually comprises a single hemisphere to hemisphere meridional circulation cell, with upwelling air in the summer hemisphere and sub- siding air at the winter pole with an associated winter polar vortex. Titan has an axial tilt (obliquity) of 26.7°, so during its 29.5 Earth year annual cycle pronounced seasonal effects are encountered as the relative solar insolation in each hemisphere changes. The most dramatic of these changes is the reversal in global meridional circulation as the peak solar heating switches hemispheres after an equinox. Titan's northern spring equinox occurred in August 2009, and since then many middle-atmosphere changes have been observed by Cassini that were previously impossible to study (1,2,3,4). Here we present a detailed analysis of the post equinox changes in middle-atmosphere temperature and composition measured with Cassini's Composite InfraRed Spectrometer (CIRS), use these to infer changes in atmospheric circulation, and explore implications for atmospheric photochemical and dynamical processes. Our results show that the meridional circulation has now reversed (1).

  9. Atmospheric oxygenation caused by a change in volcanic degassing pressure.

    Science.gov (United States)

    Gaillard, Fabrice; Scaillet, Bruno; Arndt, Nicholas T

    2011-10-12

    The Precambrian history of our planet is marked by two major events: a pulse of continental crust formation at the end of the Archaean eon and a weak oxygenation of the atmosphere (the Great Oxidation Event) that followed, at 2.45 billion years ago. This oxygenation has been linked to the emergence of oxygenic cyanobacteria and to changes in the compositions of volcanic gases, but not to the composition of erupting lavas--geochemical constraints indicate that the oxidation state of basalts and their mantle sources has remained constant since 3.5 billion years ago. Here we propose that a decrease in the average pressure of volcanic degassing changed the oxidation state of sulphur in volcanic gases, initiating the modern biogeochemical sulphur cycle and triggering atmospheric oxygenation. Using thermodynamic calculations simulating gas-melt equilibria in erupting magmas, we suggest that mostly submarine Archaean volcanoes produced gases with SO(2)/H(2)S atmosphere.

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

    Science.gov (United States)

    Yu, Hang

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

  11. Change in global aerosol composition since preindustrial times

    NARCIS (Netherlands)

    Tsigaridis, K.; Krol, M.C.; Dentener, F.; Balkanski, Y.; Lathiere, J.; Metzger, S.; Hauglustaine, D.; Kanakidou, M.

    2006-01-01

    To elucidate human induced changes of aerosol load and composition in the atmosphere, a coupled aerosol and gas-phase chemistry transport model of the troposphere and lower stratosphere has been used. The present 3-D modeling study focuses on aerosol chemical composition change since preindustrial t

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

    Science.gov (United States)

    Slowik, Jay G.

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

  13. Tropospheric Composition Change observed from Space (Invited)

    Science.gov (United States)

    Richter, A.; Hilboll, A.; Leitao, J.; Vrekoussis, M.; Wittrock, F.; Burrows, J. P.

    2010-12-01

    The composition of the troposphere is largely influenced by surface emissions of both natural and anthropogenic origins. These emissions change over time as result of human activities and natural variability, leading to varying atmospheric levels of primary and secondary pollutants. Satellite observations of sun light scattered back by the surface and the atmosphere can be used to retrieve information on atmospheric trace gases by application of optical absorption spectroscopy. In the UV and visible part of the spectrum, these measurements have good sensitivity to the lower troposphere providing information on relevant species such as O3, NO2, SO2, HCHO or glyoxal. Here, we report on recent results on tropospheric composition changes obtained from the GOME, SCIAMACHY and GOME-2 instruments which have a combined data record of nearly 15 years. The focus is on NO2 which shows an increasing trend over Asia and many large cities in countries with growing economies. At the same time, significant reductions are observed over the US and Europe, probably as result of changes in environmental legislation. SO2 signals have been decreasing over the US since 1996 while a strong upward trend was evident over China until recently when desulphurisation of power plant emissions came into effect. There also is evidence for increases in VOC levels over China which could be either of anthropogenic origin or from biogenic emissions.

  14. Atmospheric oxygenation caused by a change in volcanic degassing pressure

    OpenAIRE

    Gaillard, Fabrice; Scaillet, Bruno; Arndt, Nicholas T.

    2011-01-01

    International audience; The Precambrian history of our planet is marked by two major events: a pulse of continental crust formation at the end of the Archaean eon and a weak oxygenation of the atmosphere (the Great Oxidation Event) that followed, at 2.45 billion years ago. This oxygenation has been linked to the emergence of oxygenic cyanobacteria1,2 and to changes in the compositions of volcanic gases3,4, but not to the composition of erupting lavas--geochemical constraints indicate that the...

  15. Lunar atmospheric composition results from Apollo 17

    Science.gov (United States)

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

    1973-01-01

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

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

    OpenAIRE

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

    2007-01-01

    The isotopic composition of long-lived trace molecules provides a window into atmospheric transport and chemistry. Carbon dioxide is a particularly powerful tracer, because its abundance remains >100 parts per million by volume (ppmv) in the mesosphere. Here, we successfully reproduce the isotopic composition of CO2 in the middle atmosphere, which has not been previously reported. The mass-independent fractionation of oxygen in CO2 can be satisfactorily explained by the exchange reaction with...

  17. Postpartum changes in body composition.

    Science.gov (United States)

    Cho, Geum Joon; Yoon, Hyo Jin; Kim, Eung-Ju; Oh, Min-Jeong; Seo, Hong-Seog; Kim, Hai-Joong

    2011-12-01

    Parity is associated with weight retention and has long-lasting and detrimental effects on the health of women. Previous studies have shown that increasing parity was independently associated with an increased prevalence of metabolic syndrome. Postpartum weight is made up of several components including uterine and mammary tissues, body water (intracellular (ICW) and extracellular water (ECW)), and fat. These components change in variable amounts postpartum, thereby distinctly affecting the interpretation of individual weight retention; however, it is unclear which components contribute to weight retention. The aims of this longitudinal study were to evaluate changes in body composition during the postpartum period and to investigate their effects on weight retention. This prospective study examined 41 healthy, pregnant women who gave birth at Korea University Guro Hospital. We measured body composition at 2 days, 2 weeks, and 6 weeks postpartum using bioelectrical impedance analysis. Weight decreased during this postpartum period (P < 0.001); the postpartum weight retention from prepregnancy to 6 weeks postpartum was 4.43 ± 4.0 kg. Among various body composition components, ECW, ICW, total body water, and fat-free mass (FFM) decreased postpartum. However, fat mass (FM) and visceral fat area, the components that experienced the greatest changes, increased postpartum. Our results demonstrate that the postpartum period is associated with a preferential accumulation of adipose tissue in the visceral compartment, even though overall body weight is decreased. Further studies are needed to evaluate the changes in body composition over longer time periods and their long-term effects on health.

  18. Atmospheric Aerosols in a Changing World

    Science.gov (United States)

    Heald, C. L.

    2015-12-01

    Aerosols in the atmosphere impact human and environmental health, visibility, and climate. Exposure to air pollution is the leading environmental cause of premature mortality world-wide. The role of aerosols on the Earth's climate represents the single largest source of uncertainty in our understanding of global radiative forcing. Tremendous strides have been made to clean up the air in recent decades, and yet poor air quality continues to plague many regions of the world, and our understanding of how global change will feedback on to aerosol sources, formation, and impacts is limited. In this talk, I will use recent results from my research group to highlight some of the key uncertainties and research topics in global aerosol lifecycle.

  19. A Community-oriented CEOS Atmospheric Composition Portal (ACP)

    Science.gov (United States)

    Bernonville, S.; Goussev, O.; Falke, S.; Lindsay, F.; Lynnes, C. S.; Yang, W.; Zhao, P.; Johnson, J.

    2012-04-01

    The Atmospheric Composition Constellation (ACC) and the Workgroup for Information Systems and Services (WGISS) within the Committee on Earth Observation Satellites (CEOS) is developing a portal to support interoperability among the atmospheric composition research and applications communities. The CEOS Atmospheric Composition Portal (ACP) is defining approaches for providing data access, tools and contextual guidance for an international suite of remote sensing datasets. An initial prototype provides access to data services and analysis tools hosted by the World Data Center for Remote Sensing of the Atmosphere (WDC-RSAT), NASA's Goddard Earth Sciences Data and Information Services Center (GES DISC) and DataFed. Distributed access to data is implemented via interoperability standards, including the Open Geospatial Consortium's (OGC) Web Map Service (WMS) and Web Coverage Service (WCS). A fundamental aspect to the design, implementation and evolution of the ACP is community collaboration. The portal is intended as a community resource that is created through collaboration across remotely sensed atmospheric composition data organizations and used by a variety of groups across the climate, air quality, and stratospheric ozone domains. The implementation of interoperability standards in the ACP has involved coordination on identifying the most applicable standards and the definition of community-specific conventions to ensure consistent adoption of standards. This presentation includes an overview of the ACP, its community oriented approach, and use of community-conventions in achieving standards-based interoperability.

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

    Science.gov (United States)

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

    2016-04-01

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

  1. Mechanisms affecting the composition of Hot Jupiters atmospheres

    Directory of Open Access Journals (Sweden)

    Showman Adam P.

    2013-04-01

    Full Text Available Opacities and thus local chemical composition play a key role when characterizing exoplanet atmospheres from observations. When the gas is in chemical equilibrium the chemical abundances depend strongly on the temperature profile. Grey models tend to overestimate the temperatures in the upper atmosphere. We present a new analytical model with a more realistic description of the radiative cooling in the infrared. Mechanisms like quenching and cold traps can drive the upper atmosphere far from its chemical equilibrium. The efficiency of these mechanisms depends on the strength of the vertical mixing. Using 3D global circulation models of HD209458b including passive tracers, we show that, although Hot Jupiter atmospheres are stably stratified, they are strongly mixed by planetary scale circulation patterns. We provide a rough estimate of the effective vertical mixing coefficient in Hot Jupiter atmosphere which can be used in 1D models.

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

    Science.gov (United States)

    Kempler, S.

    2005-01-01

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

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

    Science.gov (United States)

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

    1970-01-01

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

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

    Science.gov (United States)

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

    2015-12-01

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

  5. Atmospheric General Circulation Changes under Global Warming

    Science.gov (United States)

    Palipane, Erool

    The work in this thesis is mainly two-fold. First we study the internal variability of the general circulation and focus our study on the annular modes and how important it is to simulate the subsynoptic scales in the circulation. In the next major section we will try to understand the mechanisms of the forced response and the mechanisms leading towards the jet shift from transient evolution in Atmospheric general circulation models. In the first part, in an attempt to assess the benefit of resolving the sub-synoptic to mesoscale processes, the spatial and temporal characteristics of the Annular Modes (AMs), in particular those related to the troposphere-stratosphere interaction, are evaluated for moderate- and high-horizontal resolution simulations with a global atmospheric general circulation model (AGCM), in comparison with the ERA40 re- analysis. Relative to the CMIP-type climate models, the IFS AGCM demonstrates notable improvement in capturing the key characteristics of the AMs. Notably, the performance with the high horizontal resolution version of the model is systematically superior to the moderate resolution on all metrics examined, including the variance of the AMs at different seasons of the year, the intrinsic e-folding time scales of the AMs, and the downward influence from the stratosphere to troposphere in the AMs. Moreover, the high-resolution simulation with a greater persistence in the intrinsic variability of the SAM projects an appreciably larger shift of the surface westerly wind during the Southern Hemisphere summer under climate change. In the second part, the response of the atmospheric circulation to greenhouse gas-induced SST warming is investigated using large ensemble experiments with two AGCMs, with a focus on the robust feature of the poleward shift of the eddy driven jet. In these experiments, large ensembles of simulations are conducted by abruptly switching the SST forcing on from January 1st to focus on the wintertime circulation

  6. Regional atmospheric composition modeling with CHIMERE

    Science.gov (United States)

    Menut, L.; Bessagnet, B.; Khvorostyanov, D.; Beekmann, M.; Colette, A.; Coll, I.; Curci, G.; Foret, G.; Hodzic, A.; Mailler, S.; Meleux, F.; Monge, J.-L.; Pison, I.; Turquety, S.; Valari, M.; Vautard, R.; Vivanco, M. G.

    2013-01-01

    Tropospheric trace gas and aerosol pollutants have adverse effects on health, environment and climate. In order to quantify and mitigate such effects, a wide range of processes leading to the formation and transport of pollutants must be considered, understood and represented in numerical models. Regional scale pollution episodes result from the combination of several factors: high emissions (from anthropogenic or natural sources), stagnant meteorological conditions, velocity and efficiency of the chemistry and the deposition. All these processes are highly variable in time and space, and their relative importance to the pollutants budgets can be quantified within a chemistry-transport models (CTM). The offline CTM CHIMERE model uses meteorological model fields and emissions fluxes and calculates deterministically their behavior in the troposphere. The calculated three-dimensional fields of chemical concentrations can be compared to measurements to analyze past periods or used to make air quality forecasts and CHIMERE has enabled a fine understanding of pollutants transport during numerous measurements campaigns. It is a part of the PREVAIR french national forecast platform, delivering pollutant concentrations up to three days in advance. The model also allows scenario studies and long term simulations for pollution trends. The modelling of photochemical air pollution has reached a good level of maturity, and the latest projects involving CHIMERE now aim at increasing our understanding of pollution impact on health at the urban scale or at the other end of the spectrum for long term air quality and climate change interlinkage studies, quantifying the emissions and transport of pollen, but also, at a larger scale, analyzing the transport of pollutants plumes emitted by volcanic eruptions and forest fires.

  7. Regional atmospheric composition modeling with CHIMERE

    Directory of Open Access Journals (Sweden)

    L. Menut

    2013-01-01

    Full Text Available Tropospheric trace gas and aerosol pollutants have adverse effects on health, environment and climate. In order to quantify and mitigate such effects, a wide range of processes leading to the formation and transport of pollutants must be considered, understood and represented in numerical models. Regional scale pollution episodes result from the combination of several factors: high emissions (from anthropogenic or natural sources, stagnant meteorological conditions, velocity and efficiency of the chemistry and the deposition. All these processes are highly variable in time and space, and their relative importance to the pollutants budgets can be quantified within a chemistry-transport models (CTM. The offline CTM CHIMERE model uses meteorological model fields and emissions fluxes and calculates deterministically their behavior in the troposphere. The calculated three-dimensional fields of chemical concentrations can be compared to measurements to analyze past periods or used to make air quality forecasts and CHIMERE has enabled a fine understanding of pollutants transport during numerous measurements campaigns. It is a part of the PREVAIR french national forecast platform, delivering pollutant concentrations up to three days in advance. The model also allows scenario studies and long term simulations for pollution trends. The modelling of photochemical air pollution has reached a good level of maturity, and the latest projects involving CHIMERE now aim at increasing our understanding of pollution impact on health at the urban scale or at the other end of the spectrum for long term air quality and climate change interlinkage studies, quantifying the emissions and transport of pollen, but also, at a larger scale, analyzing the transport of pollutants plumes emitted by volcanic eruptions and forest fires.

  8. Atmospheric pressure plasma assisted calcination of composite submicron fibers

    Science.gov (United States)

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

    2016-08-01

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

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

    Science.gov (United States)

    Voulgarakis, Apostolos; Field, Robert D.

    2015-01-01

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

  10. Oxygen Isotopic Composition of Carbon Dioxide in the Middle Atmosphere

    Science.gov (United States)

    Liang, M.; Blake, G. A.; Lewis, B. R.; Yung, Y. L.

    2005-12-01

    The isotopic composition of long-lived trace gases provides a window into atmospheric transport and chemistry. Carbon dioxide is a particularly powerful tracer, because its abundance remains >100 ppmv in the mesosphere. Current models consider O3 as the main source of O(1D) in the mesosphere, but we note that the photolysis of 16O17O and 16O18O by solar Lyman-α radiation yields O(1D) 10-100 times more enriched in 17O and 18O than that from ozone photodissociation. We therefore incorporate both photochemical sources into stratospheric and mesospheric chemical transport models that quantitatively predict the unusual enhancement of 17O in CO2 from the middle atmosphere. New laboratory and atmospheric measurements are proposed to test our model and validate the use of CO2 isotopic fractionation as a tracer of atmospheric chemical and dynamical processes. Once fully understood the `anomalous' oxygen signature in CO2 can be used in turn to study biogeochemical cycles, in particular to constrain the gross carbon fluxes between the atmosphere and terrestrial biosphere.

  11. Interdecadal change of atmospheric stationary waves and North China drought

    Institute of Scientific and Technical Information of China (English)

    Dai Xin-Gang; Fu Cong-Bin; Wang Ping

    2005-01-01

    The inderdecadal change of atmospheric stationary waves (ATW) has been investigated for the two periods 1956-77 and 1978-99. The trough of ATW in the middle and low layer of the troposphere over the Asian continent has experienced a significant weakening during the past two decades, which exerts a great influence on the North China climate. The ATW in 200 hPa has also exhibited some changes since 1977, as a stationary ridge appeared over the northwestern China while a stationary trough appeared above North China. This leads to an increasing of the upward motion above northwestern China and a decreasing above North China. A west-east section of the stationary waves at 40°N shows that the ATW above North China tilted westward for the period 1956-77, but was almost upright during 1978-99. The composite analysis confirms that the climate mean ATW pattern after 1977 is similar to the dry pattern for North China, while the rainy pattern is similar to that before 1977. In consequence, the North China drought is partly due to the interdecadal change of the ATW over boreal Asia in the recent two decades.

  12. Stable isotope composition of atmospheric carbon monoxide. A modelling study

    Energy Technology Data Exchange (ETDEWEB)

    Gromov, Sergey S.

    2014-11-01

    when explicitly simulated. The inaccurate surface emissions, likely underestimated over East Asia, are responsible for roughly half of the discrepancies between the simulated and observed {sup 13}CO in the northern hemisphere (NH), whereas the remote southern hemisphere (SH) compositions suggest an underestimated fractionation during the oxidation of CO by the hydroxyl radical (OH). A reanalysis of the kinetic isotope effect (KIE) in this reaction contrasts the conventional assumption of a mere pressure dependence, and instead suggests an additional temperature dependence of the {sup 13}C KIE, which is driven by changes in the partitioning of the reaction exit channels. This result is yet to be confirmed in the laboratory. Apart from {sup 13}CO, for the first time the atmospheric distribution of the oxygen mass-independent fractionation (MIF) in CO, Δ{sup 17}O, has been consistently simulated on the global scale with EMAC. The applicability of Δ{sup 17}O(CO) observations to unravelling changes in the tropospheric CH{sub 4}-CO-OH system has been scrutinised, as well as the implications of the ozone (O{sub 3}) input to the CO isotope oxygen budget. The Δ{sup 17}O(CO) is confirmed to be the principal signal for the CO photochemical age, thus providing a measure for the OH chiefly involved in the sink of CO. The highly mass-independently fractionated O{sub 3} oxygen is estimated to comprise around 2% of the overall tropospheric CO source, which has implications for the δ{sup 18}O, but less likely for the Δ{sup 17}O CO budgets. Finally, additional sensitivity simulations with EMAC corroborate the nearly equal net effects of the present-day CH{sub 4} and CO burdens in removing tropospheric OH, as well as the large turnover and stability of the abundance of the latter. The simulated CO isotopologues nonetheless hint at a likely insufficient OH regeneration in the NH high latitudes and the upper troposphere / lower stratosphere (UTLS).

  13. Effects of eustatic sea-level change, ocean dynamics, and nutrient utilization on atmospheric pCO2 and seawater composition over the last 130 000 years: a model study

    Science.gov (United States)

    Wallmann, K.; Schneider, B.; Sarnthein, M.

    2016-02-01

    We have developed and employed an Earth system model to explore the forcings of atmospheric pCO2 change and the chemical and isotopic evolution of seawater over the last glacial cycle. Concentrations of dissolved phosphorus (DP), reactive nitrogen, molecular oxygen, dissolved inorganic carbon (DIC), total alkalinity (TA), 13C-DIC, and 14C-DIC were calculated for 24 ocean boxes. The bi-directional water fluxes between these model boxes were derived from a 3-D circulation field of the modern ocean (Opa 8.2, NEMO) and tuned such that tracer distributions calculated by the box model were consistent with observational data from the modern ocean. To model the last 130 kyr, we employed records of past changes in sea-level, ocean circulation, and dust deposition. According to the model, about half of the glacial pCO2 drawdown may be attributed to marine regressions. The glacial sea-level low-stands implied steepened ocean margins, a reduced burial of particulate organic carbon, phosphorus, and neritic carbonate at the margin seafloor, a decline in benthic denitrification, and enhanced weathering of emerged shelf sediments. In turn, low-stands led to a distinct rise in the standing stocks of DIC, TA, and nutrients in the global ocean, promoted the glacial sequestration of atmospheric CO2 in the ocean, and added 13C- and 14C-depleted DIC to the ocean as recorded in benthic foraminifera signals. The other half of the glacial drop in pCO2 was linked to inferred shoaling of Atlantic meridional overturning circulation and more efficient utilization of nutrients in the Southern Ocean. The diminished ventilation of deep water in the glacial Atlantic and Southern Ocean led to significant 14C depletions with respect to the atmosphere. According to our model, the deglacial rapid and stepwise rise in atmospheric pCO2 was induced by upwelling both in the Southern Ocean and subarctic North Pacific and promoted by a drop in nutrient utilization in the Southern Ocean. The deglacial sea

  14. Atmospheric pressure changes and unexplained variability in INR measurements.

    Science.gov (United States)

    Ernst, Michael E; Shaw, Robert F; Ernst, Erika J; Alexander, Bruce; Kaboli, Peter J

    2009-06-01

    Changes in atmospheric pressure may influence hepatic blood flow and drug metabolism. Anecdotal experience suggests international normalized ratio (INR) variability may be temporally related to significant atmospheric pressure changes. We investigated this potential association in a large sample of patients with multiple INRs. This is a retrospective review of outpatient anticoagulation records from the Iowa City Veteran's Affairs Medical Center and affiliated outpatient clinics from October 1999 to July 2007. All patients, receiving at least one prescription for warfarin and INR at least 30 days or more from the date of the first warfarin prescription, were identified. INRs during periods of hospitalization and vitamin K use were excluded. Proximity analysis using geocoding of ZIP codes of identified patients to the nearest National Oceanic and Atmospheric Administration station was performed to assign atmospheric pressure with INR. Spearman's Rho and Pearson's correlation were used to evaluate atmospheric pressure and INR. Unique patients (1441) with 45 187 INRs were analyzed. When limited to nontherapeutic INRs following a previously therapeutic INR (1121 unique patients/5256 INRs), a small but clinically insignificant association between delta INR and delta atmospheric pressure was observed (r = -0.025; P = 0.038), but not for actual INR and atmospheric pressure (P = 0.06). Delta atmospheric pressure demonstrated greater variation during fall/winter months compared with spring/summer (0.23 vs. 0.15 inHg; P atmospheric pressure changes and INR variability. These findings refute the anecdotal experience seen in our anticoagulation clinic.

  15. Towards an exploitation of IAGOS atmospheric composition measurements

    Science.gov (United States)

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

    2015-04-01

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

  16. Nanostructured Sulfide Composite Coating Prepared by Atmospheric Plasma Spraying

    Institute of Scientific and Technical Information of China (English)

    关耀辉

    2006-01-01

    Nanostructured FeS-SiC coating was deposited by atmospheric plasma spraying (APS). The microstructure and phase composition of the coating were characterized with SEM and XRD, respectively. In addition, the size distribution of the reconstituted powders and the porosity of the coating have been measured. It was found that the reconstitiuted powers with sizes in the range of 20 to 80 μm had excellent flowability and were suitable for plasma spraying process. The assprayed FeS-SiC composite coating exhibited a bimodal distribution with small grains (30~80nm) and large grains (100~200nm). The coating was mainly composed of FeS and SiC, a small quantity of Fe1-x S and oxide were also found. The porosity of the coating was approximately 19 %.

  17. Atmospheric dynamics: Arctic winds of change

    Science.gov (United States)

    Notz, Dirk

    2016-09-01

    The Earth's climate evolves in response to both externally forced changes and internal variability. Now research suggests that both drivers combine to set the pace of Arctic warming caused by large-scale sea-ice loss.

  18. Computer simulations of the atmospheric composition climate of Bulgaria

    Energy Technology Data Exchange (ETDEWEB)

    Gadzhev, G.; Ganev, K.; Syrakov, D.; Prodanova, M.; Georgieva, I.; Georgiev, G.

    2015-07-01

    Some extensive numerical simulations of the atmospheric composition fields in Bulgaria have been recently performed. The US EPA Model-3 system was chosen as a modelling tool. As the NCEP Global Analysis Data with 1 degree resolution was used as meteorological background, the MM5 and CMAQ nesting capabilities were applied for downscaling the simulations to a 3 km resolution over Bulgaria. The TNO emission inventory was used as emission input. Special pre-processing procedures are created for introducing temporal profiles and speciation of the emissions. The biogenic emissions of VOC are estimated by the model SMOKE. The simulations were carried out for years 2000-2007. The numerical experiments have been carried out for different emission scenarios, which makes it possible the contribution of emissions from different source categories to be evaluated. The Models-3 Integrated Process Rate Analysis option is applied to discriminate the role of different dynamic and chemical processes for the air pollution formation. The obtained ensemble of numerical simulation results is extensive enough to allow statistical treatment calculating not only the mean concentrations and different source categories contribution mean fields, but also standard deviations, skewness, etc. with their dominant temporal modes (seasonal and/or diurnal variations). Thus some basic facts about the atmospheric composition climate of Bulgaria can be retrieved from the simulation ensemble. (Author)

  19. On Modeling the Upper Atmosphere and Ionosphere Response to Global Change

    Science.gov (United States)

    Roble, R. G.; Solomon, S. C.

    2005-05-01

    Ice core records indicate that the temperature and composition of the atmosphere can change significantly over geologic times. These changes occur naturally, however, recently the releases of trace gases from human activity have been recognized to have a potential for causing a significant change in the climate of the Earth. Most of the effort in investigating the global response to these trace gases has been directed toward the troposphere and stratosphere. Studies have shown that the troposphere will warm and the stratosphere will cool as trace gas concentrations increase in the 21st century. Studies have also been made that suggest that the mesosphere and thermosphere could also cool and affect the compositional structure of the upper atmosphere and ionosphere. We first review previous studies of the upper atmosphere and ionosphere response to trace gas increases. We then use both a global average model and the NCAR Thermosphere - Ionosphere - Mesosphere - Electrodynamics General Circulation Model (TIME-GCM) to investigate the atmospheric response to various scenarios of trace gas increases and compare the modeling results to the present day upper atmosphere and ionosphere structure. We will also discuss the key aeronomic processes that control the structure of the upper atmosphere as well as the extent to which these processes are known.

  20. Global Change in Earth's Atmosphere: Natural and Anthropogenic Factors

    Science.gov (United States)

    Lean, J.

    2013-12-01

    To what extent is human activity, such as the emission of carbon dioxide and other 'greenhouse' gases, influencing Earth's atmosphere, compared with natural variations driven by, for example, the Sun or volcanoes? Why has Earth's surface warmed barely, if at all, in the last decade? Why is the atmosphere at just 20 km above the surface cooling instead of warming? When - and will - the ozone layer recover from its two-decade decline due to chlorofluorocarbon depletion? Natural and anthropogenic factors are changing Earth's atmosphere, each with distinct temporal, geographical and altitudinal signatures. Increasing greenhouse gases, for example, warm the surface but cool the stratosphere and upper atmosphere. Aerosols injected into the stratosphere during a volcanic eruption warm the stratosphere but cool the surface. Increases in the Sun's brightness warm Earth's atmosphere, throughout. This talk will quantify and compare a variety of natural and human influences on the Earth's atmosphere, extracted statistically from multiple datasets with the goal of understanding how and why Earth's atmosphere is changing. The extent to which responses to natural influences are presently masking or exacerbating ongoing responses to human activity is examined. Scenarios for future levels of anthropogenic gases and solar activity are then used to speculate how Earth's atmosphere might evolve in future decades, according to both statistical models of the databases and physical general circulation models.

  1. Atmospheric chemistry and physics from air pollution to climate change

    CERN Document Server

    Seinfeld, John H

    2016-01-01

    Expanded and updated with new findings and new features Since the second edition of Seinfeld and Pandis’ classic textbook, significant progress has taken place in the field of atmospheric chemistry and physics, particularly in the areas of tropospheric chemistry, aerosols, and the science of climate change. A new edition of this comprehensive work has been developed by the renowned author team. Atmospheric Chemistry and Physics, 3rd Edition, as the previous two editions have done, provides a rigorous and comprehensive treatment of the chemistry and physics of the atmosphere – including the chemistry of the stratosphere and troposphere, aerosol physics and chemistry, atmospheric new particle formation, physical meteorology, cloud physics, global climate, statistical analysis of data, and mathematical chemical/transport models of the atmosphere. Each of these topics is covered in detail and in each area the central results are developed from first principles. In this way the reader gains a significant un...

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

    Science.gov (United States)

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

    2016-12-01

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

  3. Early action on HFCs mitigates future atmospheric change

    Science.gov (United States)

    Hurwitz, Margaret M.; Fleming, Eric L.; Newman, Paul A.; Li, Feng; Liang, Qing

    2016-11-01

    As countries take action to mitigate global warming, both by ratifying the UNFCCC Paris Agreement and enacting the Kigali Amendment to the Montreal Protocol to manage hydrofluorocarbons (HFCs), it is important to consider the relative importance of the pertinent greenhouse gases and the distinct structure of their atmospheric impacts, and how the timing of potential greenhouse gas regulations would affect future changes in atmospheric temperature and ozone. HFCs should be explicitly considered in upcoming climate and ozone assessments, since chemistry-climate model simulations demonstrate that HFCs could contribute substantially to anthropogenic climate change by the mid-21st century, particularly in the upper troposphere and lower stratosphere i.e., global average warming up to 0.19 K at 80 hPa. The HFC mitigation scenarios described in this study demonstrate the benefits of taking early action in avoiding future atmospheric change: more than 90% of the climate change impacts of HFCs can be avoided if emissions stop by 2030.

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

    Science.gov (United States)

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

    2016-08-01

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

  5. A study on major inorganic ion composition of atmospheric aerosols.

    Science.gov (United States)

    Salve, P R; Krupadam, R J; Wate, S R

    2007-04-01

    Atmospheric aerosol samples were collected from Akola and Buldana region covering around 40 sqkm area during October-November 2002 and were analyzed for ten major inorganic ions namely F-, Cl-, NO3-, SO4(2-), PO4(2-), Na+, K+, Ca2+, Mg2+ and NH4+ using ion chromatographic technique. The average mass of aerosols was found to be 225.81 microg/m3 with standard deviation of 31.29 and average total water soluble load of total cations and anions was found to be 4.32 microg/m3. The concentration of ions in samples showed a general pattern as SO4(2-) > NO3- > Cl- > PO4(2-) > F- for anions and Na+ > Ca2+ > NH4+ > Mg2+ > K+ for cations. The overall composition of the aerosols was taken into account to identify the sources. The trend showed higher concentration of sodium followed by calcium, sulfate, nitrate, phosphate and ammoinum and found to be influenced by terrestrial sources. The presence of SO4(2-) and NO3- in aerosols may be due to re-suspension of soil particles. Ca2+, Mg2+ and Cl- are to be derived from soil materials. The presence of NH4+ may be attributed to the reaction of NH3 vapors with acidic gases may react or condense on an acidic particle surface of anthropogenic origin. The atmospheric aerosol is slightly acidic due to neutralization of basicity by SO2 and NO(x).

  6. Ocean biogeochemistry and atmospheric composition: Significance of the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.; Jayakumar, D.A.

    character of CO 2 , respiration and photo synthesis cause a decrease and an increase of sea water pH, respectively. The relatively high pH of oceanic surface waters keeps pCO 2 at moderately low levels (Figure 3). This is largely responsible for Figure 1... productivity and hence in the rate at which CO 2 is removed from the atmosphere; this in turn can force climate changes 12 . How the balance is achieved on geological time scales is an important problem that is currently attracting the attention...

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

    Science.gov (United States)

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

    2005-01-01

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

  8. Monitoring of atmospheric composition using the thermal infrared IASI/MetOp sounder

    Directory of Open Access Journals (Sweden)

    C. Clerbaux

    2009-08-01

    Full Text Available Atmospheric remote sounding from satellites is an essential component of the observational strategy deployed to monitor atmospheric pollution and changing composition. The IASI nadir looking thermal infrared sounder onboard MetOp will provide 15 years of global scale observations for a series of key atmospheric species, with unprecedented spatial sampling and coverage. This paper gives an overview of the instrument's capability for measuring atmospheric composition in the perspective of chemistry and air quality. The assessment is made in terms of species, accuracy and vertical information. Global distributions are presented for CO, CH4, O3 (total and tropospheric, HNO3, NH3, and volcanic SO2. Local distributions of organic species measured during fire events, such as C2H4, CH3OH, HCOOH, and PAN are also shown. For each species or process, the link is made to specialized papers in this issue.

  9. Simulation of cold atmospheric plasma component composition and particle densities in air

    Science.gov (United States)

    Kirsanov, Gennady; Chirtsov, Alexander; Kudryavtsev, Anatoliy

    2015-11-01

    Recently discharges in air at atmospheric pressure were the subject of numerous studies. Of particular interest are the cold streams of air plasma, which contains large amounts of chemically active species. It is their action can be decisive in the interaction with living tissues. Therefore, in addition to its physical properties, it is important to know the component composition and particle densities. The goal was to develop a numerical model of atmospheric pressure glow microdischarge in air with the definition of the component composition of plasma. To achieve this goal the task was divided into two sub-tasks, in the first simulated microdischarge atmospheric pressure in air using a simplified set of plasma chemical reactions in order to obtain the basic characteristics of the discharge, which are the initial approximations in the problem of the calculation of the densities with detailed plasma chemistry, including 53 spices and over 600 chemical reactions. As a result of the model was created, which can be adapted for calculating the component composition of plasma of various sources. Calculate the density of particles in the glow microdischarges and dynamics of their change in time.

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

    Science.gov (United States)

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

    2015-12-01

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

  11. A transition in the cloud composition of hot Jupiters atmospheres

    Science.gov (United States)

    Parmentier, Vivien; Fortney, Jonathan J.; Showman, Adam P.; Morley, Caroline; Marley, Mark S.

    2016-01-01

    Over a large range of equilibrium temperatures clouds seem to dominate the transmission spectrum of Hot Jupiters atmospheres and no trend allowing the classification of these objects have yet emerged. Recently observations of the light reflected by Hot Jupiters atmospheres shed a new light on the cloud distribution on the dayside of these planets : for a handful of planets clouds are more abundant on the western than on the eastern side of the dayside hemisphere and, more importantly, this asymmetry depends on the equilibrium temperature of the planet.Here we use a grid of 3D global circulation models to show that a single cloud species is unable to explain the recent Kepler observations. The cloud asymmetry on the dayside is a strong function of the condensation temperature of the cloud species which allow us to determine the composition of the clouds present in these planets. We show that a transition between silicate clouds and sulfide clouds appear at equilibrium temperatures of 1600K. A mechanism such as the presence of a deep cold trap is necessary to explain this transi- tion. Furthermore, we show that the western limb temperature is always cold, independently of the equilibrium temperature of the planet, allowing cloud particles to form even in the most irradiated planets as seen in the observations.Our results provide the first evidence for a transition in the cloud species of hot Jupiters similar to the L/T Brown Dwarf transition. We further show that inhomogeneous dayside and limbs cloud coverage are expected what should affect the retrieved molecular abundances from emission and transmission spectra of these planets.

  12. Body Composition Changes Associated With Methadone Treatment

    Directory of Open Access Journals (Sweden)

    Sadek

    2016-02-01

    Full Text Available Background Methadone is associated with a statistically significant increase in BMI in the first 2 years of treatment. Objectives To evaluate the changes of body composition (bone mass, % fat, % muscle mass, % water, and basal metabolic rate related to this increase. Patients and Methods Changes in body composition were monitored, via bioelectrical impedance, in 29 patients in methadone treatment for opiate dependency (age 18 to 44, mean = 29.3, SD = 7.0, 13 men, 16 women. Results Within one year from admission to treatment, a statistically significant (t-tests, P < 0.05 increase was noted in their body mass index (BMI, % of body fat, average body mass, and average basal metabolic rate, and relative decrease in their % of muscle mass and % of bone mass. Neither absolute bone mass nor muscle mass changed significantly. Conclusions Physicians involved in care of methadone patients should recommend dietary and lifestyle changes to improve their overall health.

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

    Science.gov (United States)

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

    2013-04-01

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

  14. Climate change and CO2 removal from the atmosphere

    NARCIS (Netherlands)

    Schuiling, R.D.

    2014-01-01

    Several methods have been proposed in recent years to counteract climate change and ocean acidification by removing CO2 from the atmosphere (Carbon Dioxide Removal). The most versatile and widely applicable of these methods is enhanced weathering of olivine, which is capable of removing billions of

  15. Modification of Composite Material Fillers by Atmospheric Plasma Discharge

    Directory of Open Access Journals (Sweden)

    David Tichy

    2013-01-01

    Full Text Available This work is focused on the observation of the influence of cold atmospheric dielectric barrier discharge (DBD on a modification of textile samples. The main objective of the experiment is to research wettability change of textiles modified by different exposure times and also the observation of the influence of a modification ageing effect. An ambient air was used as a working gas for DBD plasma. The wettability evaluation was carried out by a drop method, in which an imprint of the dropwas observed on the textile surface during various time intervals. An ageing effect of the modification was monitored within an interval of 28 days. Considerable increase of wettability of all modified samples has been proved. A fibre surface analysis was carried out by means of SEM.

  16. Effect of sintering atmosphere on composition and properties of NiFe2O4 ceramic

    Institute of Scientific and Technical Information of China (English)

    田忠良; 张腾; 刘恺; 赖延清; 李劼

    2015-01-01

    NiFe2O4 ceramics were prepared in different sintering atmospheres. The phase compositions, microstructures and mechanical properties were studied. The results show that the stoichiometric compound NiFe2O4 cannot be obtained in vacuum or atmospheres with oxygen contents of 2×10−5, 2×10−4 and 2×10−3, respectively. All the samples sintered in above-mentioned atmospheres contain phases of NiFe2O4 and NiO. With increasing oxygen content, NiFe2O4 content in the ceramic increases, while NiO content appears a contrary trend. In vacuum, NiFe2O4 ceramic has average grain size of 3.94μm, and bending strength of 85.12 MPa. The changes of the phase composition and mechanical properties of NiFe2O4 based cermets are mainly caused by the alteration of their properties of NiFe2O4 ceramic.

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

    Science.gov (United States)

    Stuart, F. M.; Mark, D.

    2012-04-01

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

  18. Periodic changes of the activity of processes in Jupiter's atmosphere

    Science.gov (United States)

    Vidmachenko, A. P.

    2016-10-01

    Variations of the Earth jovimagnetic latitude on Jupiter are preferred in solar-driven changes of reflective properties of clouds and haze on Jupiter. Because of the orbit eccentricity (e=0,048450) the northern hemisphere receives 21% greater solar energy flow to the atmosphere, because Jupiter is in the perihelia near the time of the summer solstice. Results of our studies showed that the ratio of the brightness of the northern and southern tropical and temperate regions is evident factor of the photometric activity of the Jupiter's atmospheric processes. The obtained from the analysis of observational data for the period from 1962 to 2015 existence of variations of activity factor of the planet hemispheres with a period of 11.86 years has allowed us to talk about an existence of the seasonal reconstruction of the physical parameters of Jupiter's atmosphere.

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

    Science.gov (United States)

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

    2016-09-01

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

  20. The atmospheres of the earth and the other planets: Origin, evolution and composition

    Science.gov (United States)

    Levine, Joel S.

    1988-01-01

    The current understanding of the composition, chemistry, and structure of the atmospheres of the other planets and the origin, early history, and evolution of the earth's atmosphere is reviewed. The information on the atmospheres of the other planets is based on the successful Mariner, Viking, Pioneer, and Voyager missions to these planets. The information on the origin, early history, and evolution of the atmosphere, which is somewhat speculative, is largely based on numerical studies with geochemical and photochemical models.

  1. Composition of Early Planetary Atmospheres I: Connecting Disk Astrochemistry to the Formation of Planetary Atmospheres

    CERN Document Server

    Cridland, Alex J; Alessi, Matthew

    2016-01-01

    We present a model of early planetary atmospheres which represents the cumulative gaseous chemical species that are accreted onto planets forming by core accretion from an evolving protoplanetary disk. The astrochemistry of the host disk is computed using ionization driven, non-equilibrium chemistry networks within viscously evolving disk models. We accrete gas giant planets whose evolution is controlled by planet traps using the standard core accretion model and track the chemical composition of the material that is accreted onto the protoplanet. We choose a fiducial disk model and evolve planets in 3 traps - water ice line, dead zone and heat transition. For a disk with a lifetime of $4.1$ Myr we produce two Hot Jupiters (M $= 1.43, 2.67$ M$_{\\rm Jupiter}$, r $= 0.15, 0.11$ AU) in the heat transition and ice line trap and one failed core (M $= 0.003$ M$_{\\rm Jupiter}$, r $=3.7$ AU) in the dead zone. These planets are found with mixing ratios for CO and H$_2$O of $1.99\\times 10^{-4}$, $5.0\\times 10^{-4}$ res...

  2. Neutral atmosphere composition from SOIR measurements on board Venus Express

    Science.gov (United States)

    Mahieux, A.; Drummond, R.; Wilquet, V.; Vandaele, A. C.; Federova, A.; Belyaev, D.; Korablev, O.; Villard, E.; Montmessin, F.; Bertaux, J.-L.

    2009-04-01

    The SOIR instrument performs solar occultation measurements in the IR region (2.2 - 4.3 m) at a resolution of 0.12 cm-1, the highest on board Venus Express. It combines an echelle spectrometer and an AOTF (Acousto-Optical Tunable Filter) for the order selection [1,2]. The wavelength range probed by SOIR allows a detailed chemical inventory of the Venus atmosphere above the cloud layer with an emphasis on vertical distribution of the gases. Measurements of HDO, H2O, HCl, HF, CO and CO2 vertical profiles have been routinely performed, as well as those of their isotopologues [3,4]. We will discuss the improvements introduced in the analysis algorithm of the SOIR spectra. This discussion will be illustrated by presenting new results of retrievals of minor constituents of the Venus mesosphere, in terms of vertical profiles and geographical distribution. CO2 is the major constituent of the Venus atmosphere and was therefore observed in many solar occultations, leading to a good geographical coverage, although limited by the geometry of the orbit. Depending on the abundance of the absorbing isotopologue and on the intensity of the band measured, we will show that the SOIR instrument is able to furnish CO2 vertical profiles ranging typically from 65 to 150 km, reaching in some conditions 185 km altitude. This information is important in the frame of compiling, in collaboration with other teams, a new Venus Atmosphere Model. 1. A. Mahieux, S. Berkenbosch, R. Clairquin, D. Fussen, N. Mateshvili, E. Neefs, D. Nevejans, B. Ristic, A. C. Vandaele, V. Wilquet, D. Belyaev, A. Fedorova, O. Korablev, E. Villard, F. Montmessin and J.-L. Bertaux, "In-Flight performance and calibration of SPICAV SOIR on board Venus Express", Applied Optics 47 (13), 2252-65 (2008). 2. D. Nevejans, E. Neefs, E. Van Ransbeeck, S. Berkenbosch, R. Clairquin, L. De Vos, W. Moelans, S. Glorieux, A. Baeke, O. Korablev, I. Vinogradov, Y. Kalinnikov, B. Bach, J.-P. Dubois and E. Villard, "Compact high

  3. COMPOSITION CHANGES IN REFRIGERANT BLENDS FOR AUTOMOTIVE AIR CONDITIONING

    Science.gov (United States)

    Three refrigerant blends used to replace CFC-12 in automotive air conditioners were evaluated for composition changes due to typical servicing and leakage. When recommended service procedures were followed, changes in blend compositions were relatively small. Small changes in b...

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

    Science.gov (United States)

    Edwards, D. P.

    2015-12-01

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

  5. Changes in calcification of coccoliths under stable atmospheric CO2

    DEFF Research Database (Denmark)

    Berger, C.; Meier, K. J. S.; Kinkel, H.;

    2014-01-01

    The response of coccolithophore calcification to ocean acidification has been studied in culture experiments as well as in present and past oceans. The response, however, is different between species and strains, and for the relatively small carbonate chemistry changes observed in natural...... North Atlantic Ocean. The pre-industrial Holocene, with its predominantly stable atmospheric CO2, provides the conditions for such a comprehensive analysis. For an analysis on changes in major components of Holocene coccolithophores under natural conditions, the family Noelaerhabdaceae was selected...

  6. Predictions of the Atmospheric Composition of GJ 1132b

    Science.gov (United States)

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

    2016-10-01

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

  7. Long-term change in the biogeochemical cycling of atmospheric selenium: Deposition to plants and soil

    Science.gov (United States)

    Haygarth, P. M.; Cooke, A. I.; Jones, K. C.; Harrison, A. F.; Johnston, A. E.

    1993-01-01

    Retrospective analysis of archived soil and herbage samples from Rothamsted Experimental Station, southeast England, has determined the long-term changes in selenium deposition over the last century. Three out of four soils (those under permanent grassland, or growing wheat and barley) accumulated Se at a rate of circa 0.15% yr-1 (rate based on Se concentration, normalized to the earliest date circa 100 years earlier), with a net flux in the order 60-90 μg m-2 yr-1. The increase in soil growing root crops was smaller, with an increase of only 0.07% yr-1, possibly reflecting larger volatilization losses from this soil. Herbage samples were sensitive to changes in air composition. In the earlier half of the twentieth century there was an increase in the selenium content of herbage, probably from increased atmospheric deposition following increased use of fossil fuels. However, following the Clean Air Act (1956) the atmospheric loading of Se at this UK site appears to have declined, with contemporary Se concentrations in herbage considerably lower than they were in the 1970s, probably reflecting a change in fossil fuel usage from coal to oil and gas. The atmosphere has been a significant source of Se to plants and therefore grazing livestock. If the decline in the atmospheric input of selenium to herbage continues, selenium deficiency in livestock may become more prevalent in areas where soil concentrations are marginal.

  8. Atmospheric river landfall-latitude changes in future climate simulations

    Science.gov (United States)

    Shields, Christine A.; Kiehl, Jeffrey T.

    2016-08-01

    The latitude of landfall for atmospheric rivers (ARs) is examined in the fully coupled half-degree version of the Community Climate System Model, version 4 (CCSM4) for warm future climate simulations. Two regions are examined: U.S. West Coast/North Pacific ARs and United Kingdom/North Atlantic ARs. Changes in AR landfall-latitude reflect changes in the atmospheric steering flow. West Coast U.S. ARs are projected to push equatorward in response to the subtropical jet climate change. UK AR response is dominated by eddy-driven jets and is seasonally dependent. UK simulated AR response is modest in the winter with the largest relative changes occurring in the seasonal transition months. Precipitation associated with ARs is also projected to increase in intensity under global warming. CCSM4 projects a marked shift to higher rainfall rates for Southern California. Small to modest rainfall rates may increase for all UK latitudes, for the Pacific Northwest, and central and northern California.

  9. Predictions of the atmospheric composition of GJ 1132b

    CERN Document Server

    Schaefer, Laura; Berta-Thompson, Zachory; Sasselov, Dimitar

    2016-01-01

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

  10. Atmospheric Ozone and Methane in a Changing Climate

    Directory of Open Access Journals (Sweden)

    Ivar S. A. Isaksen

    2014-07-01

    Full Text Available Ozone and methane are chemically active climate-forcing agents affected by climate–chemistry interactions in the atmosphere. Key chemical reactions and processes affecting ozone and methane are presented. It is shown that climate-chemistry interactions have a significant impact on the two compounds. Ozone, which is a secondary compound in the atmosphere, produced and broken down mainly in the troposphere and stratosphre through chemical reactions involving atomic oxygen (O, NOx compounds (NO, NO2, CO, hydrogen radicals (OH, HO2, volatile organic compounds (VOC and chlorine (Cl, ClO and bromine (Br, BrO. Ozone is broken down through changes in the atmospheric distribution of the afore mentioned compounds. Methane is a primary compound emitted from different sources (wetlands, rice production, livestock, mining, oil and gas production and landfills.Methane is broken down by the hydroxyl radical (OH. OH is significantly affected by methane emissions, defined by the feedback factor, currently estimated to be in the range 1.3 to 1.5, and increasing with increasing methane emission. Ozone and methane changes are affected by NOx emissions. While ozone in general increase with increases in NOx emission, methane is reduced, due to increases in OH. Several processes where current and future changes have implications for climate-chemistry interactions are identified. It is also shown that climatic changes through dynamic processes could have significant impact on the atmospheric chemical distribution of ozone and methane, as we can see through the impact of Quasi Biennial Oscillation (QBO. Modeling studies indicate that increases in ozone could be more pronounced toward the end of this century. Thawing permafrost could lead to important positive feedbacks in the climate system. Large amounts of organic material are stored in the upper layers of the permafrost in the yedoma deposits in Siberia, where 2 to 5% of the deposits could be organic material

  11. The increased atmospheric greenhouse effect and regional climate change

    Energy Technology Data Exchange (ETDEWEB)

    Groenaas, S. [Bergen Univ. (Norway)

    1996-03-01

    This paper was read at the workshop ``The Norwegian Climate and Ozone Research Programme`` held on 11-12 March 1996. The main information for predicting future climate changes comes from integrating coupled climate models of the atmosphere, ocean and cryosphere. Regional climate change may be studied from the global integrations, however, resolution is coarse because of insufficient computer power. Attempts are being made to get more regional details out of the global integrations by ``downscaling`` the latter. This can be done in two ways. Firstly, limited area models with high resolution are applied, driven by the global results as boundary values. Secondly, statistical relationships have been found between observed meteorological parameters, like temperature and precipitation, and analyzed large scale gridded fields. The derived relations are then used on similar data from climate runs to give local interpretations. A review is given of literature on recent observations of climate variations and on predicted regional climate change. 18 refs., 4 figs.

  12. Diffusion Dynamics with Changing Network Composition

    CERN Document Server

    Baños, Raquel A; Wang, Ning; Moreno, Yamir; González-Bailón, Sandra

    2013-01-01

    We analyze information diffusion using empirical data that tracks online communication around two instances of mass political mobilization, including the year that lapsed in-between the protests. We compare the global properties of the topological and dynamic networks through which communication took place as well as local changes in network composition. We show that changes in network structure underlie aggregated differences on how information diffused: an increase in network hierarchy is accompanied by a reduction in the average size of cascades. The increasing hierarchy affects not only the underlying communication topology but also the more dynamic structure of information exchange; the increase is especially noticeable amongst certain categories of nodes (or users). This suggests that the relationship between the structure of networks and their function in diffusing information is not as straightforward as some theoretical models of diffusion in networks imply.

  13. Oceans-land-atmosphere interactions and global change

    Digital Repository Service at National Institute of Oceanography (India)

    DileepKumar, M.

    Content-Type text/plain; charset=UTF-8 94 Oceans-Land-Atmosphere interactions and Global Change M. Dileep Kumar National Institute of Oceanography, Dona Paula, Goa-403 004. dileep@nio.org We live on land, feel the breeze and enjoy... the global climate under pressure. This has become a cause for concern internationally, but should be more to us since our monsoons could be threatened. In order to appreciate the interactions among the Earth’s surface reservoirs in relation to climate...

  14. Impacts of near-future cultivation of biofuel feedstocks on atmospheric composition and local air quality

    Science.gov (United States)

    Ashworth, K.; Folberth, G.; Hewitt, C. N.; Wild, O.

    2012-01-01

    Large-scale production of feedstock crops for biofuels will lead to land use changes. We quantify the effects of realistic land use change scenarios for biofuel feedstock production on isoprene emissions and hence atmospheric composition and chemistry using the HadGEM2 model. Two feedstocks are considered: oil palm for biodiesel in the tropics and short rotation coppice (SRC) in the mid-latitudes. In total, 69 Mha of oil palm and 9 Mha of SRC are planted, each sufficient to replace just over 1% of projected global fossil fuel demand in 2020. Both planting scenarios result in increases in total global annual isoprene emissions of about 1%. In each case, changes in surface concentrations of ozone and biogenic secondary organic aerosol (bSOA) are substantial at the regional scale, with implications for air quality standards. However, the changes in tropospheric burden of ozone and the OH radical, and hence effects on global climate, are negligible. Over SE Asia, one region of oil palm planting, increases in annual mean surface ozone and bSOA concentrations reach over 3 ppbv (+11%) and 0.4 μg m-3 (+10%) respectively for parts of Borneo, with monthly mean increases of up to 6.5 ppbv (+25%) and 0.5 μg m-3 (+12%). Under the SRC scenario, Europe experiences monthly mean changes of over 0.6 ppbv (+1%) and 0.1 μg m-3 (+5%) in June and July, with peak increases of over 2 ppbv (+3%) and 0.5 μg m-3 (+8 %). That appreciable regional atmospheric impacts result from low level planting scenarios demonstrates the need to include changes in emissions of reactive trace gases such as isoprene in life cycle assessments performed on potential biofuel feedstocks.

  15. A critique of Phanerozoic climatic models involving changes in the CO 2 content of the atmosphere

    Science.gov (United States)

    Boucot, A. J.; Gray, Jane

    2001-12-01

    Critical consideration of varied Phanerozoic climatic models, and comparison of them against Phanerozoic global climatic gradients revealed by a compilation of Cambrian through Miocene climatically sensitive sediments (evaporites, coals, tillites, lateritic soils, bauxites, calcretes, etc.) suggests that the previously postulated climatic models do not satisfactorily account for the geological information. Nor do many climatic conclusions based on botanical data stand up very well when examined critically. Although this account does not deal directly with global biogeographic information, another powerful source of climatic information, we have tried to incorporate such data into our thinking wherever possible, particularly in the earlier Paleozoic. In view of the excellent correlation between CO 2 present in Antarctic ice cores, going back some hundreds of thousands of years, and global climatic gradient, one wonders whether or not the commonly postulated Phanerozoic connection between atmospheric CO 2 and global climatic gradient is more coincidence than cause and effect. Many models have been proposed that attempt to determine atmospheric composition and global temperature through geological time, particularly for the Phanerozoic or significant portions of it. Many models assume a positive correlation between atmospheric CO 2 and surface temperature, thus viewing changes in atmospheric CO 2 as playing the critical role in regulating climate/temperature, but none agree on the levels of atmospheric CO 2 through time. Prior to the relatively recent interval of time in which atmospheric CO 2 is directly measurable, a variety of biological and geological proxies have been proposed to correlate with atmospheric CO 2 level or with pCO 2/temperature. Atmospheric models may be constructed for the Pre-Cenozoic but the difficulties of assessing variables in their construction are many and complex. None of the modelers have gathered enough biological and geological data to

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-01-10

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

  17. Southeast Pacific atmospheric composition and variability sampled along 20° S during VOCALS-REx

    Directory of Open Access Journals (Sweden)

    P. I. Williams

    2011-01-01

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

  18. Atmospheric pressure plasma treatment of glass fibre composite for adhesion improvement

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Mortensen, H.; Stenum, Bjarne

    2007-01-01

    Glass-fibre-reinforced polyester composite plates were treated with an atmospheric pressure dielectric barrier discharge. Synthetic air was used as the treatment gas. The water contact angle dropped markedly from 84 to 22° after a 2-s treatment, and decreased to 0° when the composite plates were...

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

    Science.gov (United States)

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

    2010-10-06

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

  20. Responses of northern forest plants to atmospheric changes

    Energy Technology Data Exchange (ETDEWEB)

    Laine, K.; Huttunen, S.; Kauppi, M.; Ohtonen, R.; Laehdesmaeki, P. [Oulu Univ. (Finland). Dept. of Biology

    1996-12-31

    This research programme has been under way since 1990 to study the long-term synergistic effects of air pollutants and changing climatic conditions on the northern forest ecosystem and to increase the knowledge of climatic change and its consequences for the fragile northern nature. Ecological, physiological, morphological and biochemical methods have been used to study the responses of forest trees, dwarf shrubs, lichens and soil biology to environmental changes. The research programme is divided into four subprojects concentrating on different ecosystem levels. The subprojects are: (1) life, growth and survival strategies of northern dwarf shrubs under the pressure of a changing environment, (2) forest trees under the impact of air pollutants, increasing CO{sub 2} and UV-B, (3) susceptibility of lichens to air pollution and climatic change and (4) impact of elevated atmospheric CO{sub 2} and O{sub 3} on soil biology with special reference to carbon allocation and N fixation in symbiotic systems. This report summarizes the results of short-term experiments which showed many ecological and physiological changes in almost all elements of the northern boreal forests. These species-level measurements focused on the key species of the northern boreal forest, which have been thought to be useful in large-scale ecosystem experiments and modelling. The results will also facilitate the further studies on the patterns of plant species distribution and northern ecosystem function with respect to the environmental parameters that are expected to change along with global change (e.g. temperature, airchemistry, UV-B, snow condition)

  1. Multi-scale Model of Residual Strength of 2D Plain Weave C/SiC Composites in Oxidation Atmosphere

    Science.gov (United States)

    Chen, Xihui; Sun, Zhigang; Sun, Jianfen; Song, Yingdong

    2016-06-01

    Multi-scale models play an important role in capturing the nonlinear response of woven carbon fiber reinforced ceramic matrix composites. In plain weave carbon fiber/silicon carbon (C/SiC) composites, the carbon fibers and interphases will be oxidized at elevated temperature and the strength of the composite will be degraded when oxygen enters micro-cracks formed in the as-produced parts due to the mismatch in thermal properties between constituents. As a result of the oxidation on fiber surface, fiber shows a notch-like morphology. In this paper, the change rule of fiber notch depth is fitted by circular function. And a multi-scale model based upon the change rule of fiber notch depth is developed to simulate the residual strength and post-oxidation stress-strain curves of the composite. The multi-scale model is able to accurately predict the residual strength and post-oxidation stress-strain curves of the composite. Besides, the simulated residual strength and post-oxidation stress-strain curves of 2D plain weave C/SiC composites in oxidation atmosphere show good agreements with experimental results. Furthermore, the oxidation time and temperature of the composite are investigated to show their influences upon the residual strength and post-oxidation stress-strain curves of plain weave C/SiC composites.

  2. Earth's changing global atmospheric energy cycle in response to climate change.

    Science.gov (United States)

    Pan, Yefeng; Li, Liming; Jiang, Xun; Li, Gan; Zhang, Wentao; Wang, Xinyue; Ingersoll, Andrew P

    2017-01-24

    The Lorenz energy cycle is widely used to investigate atmospheres and climates on planets. However, the long-term temporal variations of such an energy cycle have not yet been explored. Here we use three independent meteorological data sets from the modern satellite era, to examine the temporal characteristics of the Lorenz energy cycle of Earth's global atmosphere in response to climate change. The total mechanical energy of the global atmosphere basically remains constant with time, but the global-average eddy energies show significant positive trends. The spatial investigations suggest that these positive trends are concentrated in the Southern Hemisphere. Significant positive trends are also found in the conversion, generation and dissipation rates of energies. The positive trends in the dissipation rates of kinetic energies suggest that the efficiency of the global atmosphere as a heat engine increased during the modern satellite era.

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

    Science.gov (United States)

    Bacon, Karen; Haworth, Matthew; McElwain, Jennifer

    2016-04-01

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

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

    Science.gov (United States)

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

    1997-02-01

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

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

    CERN Document Server

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

    1997-01-01

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

  6. A thirty year record of the isotopic composition of atmospheric methane from North America

    Science.gov (United States)

    Rice, A. L.; Teama, D. G.; Roeger, F. H.; Butenhoff, C. L.; Khalil, A. K.

    2012-12-01

    Methane (CH4) is one of the most important greenhouse gases after water vapor and carbon dioxide. Its atmospheric concentration increased from 650 ppb during the preindustrial era to nearly 1800 ppb in the present day due to human activities such as rice cultivation, animal husbandry, biomass burning, and fossil fuel production and use. Since the 1980s, the long-term growth rate of atmospheric CH4 slowed dramatically consistent with a leveling off of CH4 sources with significant interannual variability over this period. One powerful tool to constrain changes in sources and sinks is the use of stable isotopes of atmospheric CH4 because of the distinct values of carbon isotope (δ13C) and hydrogen isotope (δD) ratios in CH4 sources and characteristic isotopic fractionation effects in sinks. Measurements of the long-term trend of the isotopic composition of CH4 can improve the constraint of changes to the CH4 budget from microbial sources (e.g., wetlands, ruminants, and rice agriculture, δ13C ~-60 ‰, δD ~-300‰), fossil sources (e.g. natural gas and coal mining, δ13C ~-40‰, δD ~-200‰), and biomass burning (δ13C ~-25‰, δD ~-100‰). In this work, we present measurements of δ13C and δD of atmospheric CH4 from a unique archive of more than 200 air samples collected at Cape Meares, Oregon (45.5°N, 124°W) from 1978 to 1998. The measurements from this archive indicate enrichments in both isotope tracers over this period which average 0.017 (±0.002) ‰yr-1 for δ13C and 0.68 (±0.04) ‰yr-1 for δD. Seasonal cycles in δ13C and δD are also evident with amplitudes of ~ 0.3 ‰ and ~ 4 ‰, respectively; maximum values are found May-July and minimum values September-December, consistent with previous results from the mid-latitude northern hemisphere. Combining our results with more recent timeseries since 1988 from Olympic Peninsula (WA, 48°N), Montana de Oro (CA, 35°N), and Niwot Ridge (CO, 40°N) provides a composite record of the isotopic

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

    Energy Technology Data Exchange (ETDEWEB)

    Moses, J. I. [Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301 (United States); Line, M. R. [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Visscher, C. [Southwest Research Institute, Boulder, CO 80302 (United States); Richardson, M. R. [Rice University, Houston, TX 77005-1892 (United States); Nettelmann, N.; Fortney, J. J. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Barman, T. S. [Lowell Observatory, Flagstaff, AZ 86001 (United States); Stevenson, K. B. [Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States); Madhusudhan, N., E-mail: jmoses@spacescience.org [Department of Physics and Department of Astronomy, Yale University, New Haven, CT 06520-8101 (United States)

    2013-11-01

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

  8. Changes in calcification of coccoliths under stable atmospheric CO2

    Science.gov (United States)

    Berger, C.; Meier, K. J. S.; Kinkel, H.; Baumann, K.-H.

    2014-02-01

    The response of coccolithophore calcification to ocean acidification has been studied in culture experiments as well as in present and past oceans. The response, however, is different between species and strains, and for the relatively small carbonate chemistry changes observed in natural environments, a uniform response of the entire coccolithophore community has not been documented so far. Moreover, previous palaeo-studies basically focus on changes in coccolith weight due to increasing CO2 and the resulting changes in the carbonate system, and only few studies focus on the influence of other environmental factors. In order to untangle changes in coccolithophore calcification due to environmental factors such as temperature and/or productivity from changes caused by increasing pCO2 and decreasing carbonate ion concentration, we here present a study on coccolith calcification from the Holocene North Atlantic Ocean. The pre-industrial Holocene, with its predominantly stable atmospheric CO2, provides the conditions for such a comprehensive analysis. For an analysis on changes in major components of Holocene coccolithophores under natural conditions, the family Noelaerhabdaceae was selected, which constitutes the main part of the assemblage in the North Atlantic. Records of average coccolith weights from three Holocene sediment cores along a north-south transect in the North Atlantic were analysed. During the Holocene, mean weight (and therefore calcification) of Noelaerhabdaceae (Emiliania huxleyi and Gephyrocapsa) coccoliths decreased at the Azores (Geofar KF 16) from around 7 to 6 pg, but increased at the Rockall Plateau (ODP site 980) from around 6 to 8 pg, and at the Vøring Plateau (MD08-3192) from 7 to 10 pg. The amplitude of average weight variability is within the range of glacial-interglacial changes that were interpreted to be an effect of decreasing carbonate ion concentration. By comparison with SEM assemblage counts, we show that weight changes are not

  9. Carbon isotopes characterize rapid changes in atmospheric carbon dioxide during the last deglaciation

    Science.gov (United States)

    Bauska, Thomas K.; Baggenstos, Daniel; Brook, Edward J.; Mix, Alan C.; Marcott, Shaun A.; Petrenko, Vasilii V.; Schaefer, Hinrich; Lee, James E.

    2016-01-01

    An understanding of the mechanisms that control CO2 change during glacial–interglacial cycles remains elusive. Here we help to constrain changing sources with a high-precision, high-resolution deglacial record of the stable isotopic composition of carbon in CO2 (δ13C-CO2) in air extracted from ice samples from Taylor Glacier, Antarctica. During the initial rise in atmospheric CO2 from 17.6 to 15.5 ka, these data demarcate a decrease in δ13C-CO2, likely due to a weakened oceanic biological pump. From 15.5 to 11.5 ka, the continued atmospheric CO2 rise of 40 ppm is associated with small changes in δ13C-CO2, consistent with a nearly equal contribution from a further weakening of the biological pump and rising ocean temperature. These two trends, related to marine sources, are punctuated at 16.3 and 12.9 ka with abrupt, century-scale perturbations in δ13C-CO2 that suggest rapid oxidation of organic land carbon or enhanced air–sea gas exchange in the Southern Ocean. Additional century-scale increases in atmospheric CO2 coincident with increases in atmospheric CH4 and Northern Hemisphere temperature at the onset of the Bølling (14.6–14.3 ka) and Holocene (11.6–11.4 ka) intervals are associated with small changes in δ13C-CO2, suggesting a combination of sources that included rising surface ocean temperature. PMID:26976561

  10. Further signatures of long-term changes in atmospheric electrical parameters observed in Europe

    Directory of Open Access Journals (Sweden)

    F. Märcz

    2005-09-01

    Full Text Available Long-term decreases found recently in both the atmospheric electrical potential gradient (PG and the air-Earth current density (Jz, using observation series from the UK and Hungary, have motivated studies of other European data. Two surface data series somewhat longer than a decade were available: PG data obtained at Serra do Pilar (Portugal, and PG, Jz and positive air conductivity measurements at Athens (Greece. Selecting data to minimise local effects, the 1960–1971 Serra do Pilar PG values decrease at dawn and in the evening. Dawn data obtained at Athens (1967–1977 indicate a reduction in Jz, while the simultaneous PG values there increase (coincident air conductivity values decrease for the periods investigated. The Athens PG increase is attributed to local aerosol influences, typical of urban environments. Despite the urban influence, the Athens Jz shows similarities with soundings of the ionospheric potential. The decline in Jz at Athens occurs simultaneously with a decrease reported previously in Jz at Kew (UK, indicating that, at least, a regional decrease in the global atmospheric electrical circuit occurred during part of the twentieth century. Similar surface changes occur in European atmospheric electrical parameters, with a decrease of about 0.5% to 0.7% per year between 1920 and 1970 (possibly extending back to 1898, an annual decrease of between 2.7 and 3.4%, between 1959 and 1971 and a continued decrease of about ~1% per year between 1967 and 1984, possibly still continuing.

    Keywords. Meteorology and atmospheric dynamics (Atmospheric electricity – Geomagnetism and paleomagnetism (Time variations, secular and long term – Atmospheric composition and structure (Aerosols and particles

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

    Science.gov (United States)

    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.

  12. South East Pacific atmospheric composition and variability sampled along 20° S during VOCALS-REx

    Directory of Open Access Journals (Sweden)

    G. Allen

    2011-06-01

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

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

    OpenAIRE

    Atri, Dimitra; Melott, Adrian L.; Thomas, Brian C

    2008-01-01

    A variety of events such as gamma-ray bursts and supernovae may expose the Earth to an increased flux of high-energy cosmic rays, with potentially important effects on the biosphere. Existing atmospheric chemistry software does not have the capability of incorporating the effects of substantial cosmic ray flux above 10 GeV . An atmospheric code, the NASA-Goddard Space Flight Center two-dimensional (latitude, altitude) time-dependent atmospheric model (NGSFC), is used to study atmospheric chem...

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

    Science.gov (United States)

    Widory, David; Javoy, Marc

    2003-10-01

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

  15. Changes in DOC treatability: Indications of compositional changes in DOC trends

    Science.gov (United States)

    Worrall, F.; Burt, T. P.

    2009-03-01

    SummaryThis study considers long-term records of the nature of water colour and coincident water quality and quantity in order to test hypotheses about increases in release of dissolved organic carbon from peat soils across the northern hemisphere. The study focuses upon the treatment ratio, i.e. the ratio of the amount of coagulant dose required to the water colour of the incoming water, and compares this ratio to possible explanatory variables: pH, conductivity, water temperature, river flow and alkalinity. The study shows that: The annual average increase in treatment ratio is just less than 6.5% over a six year period. There is a long-term increase in the treatment ratio that is independent of changes in riverflow, pH, conductivity, water temperature and alkalinity and so a real change in DOC composition is occurring. There is a seasonal cycle in treatment ratio that is also independent of the available water and climate variables. The upward trend in treatment ratio is declining with time over the study period. The observed trends in DOC composition are consistent with an explanation of increasing DOC concentration and flux based upon changes in flow and temperature but is not consistent with present explanations based upon changes in atmospheric deposition or upon drought unless the effect of the drought are short-lived (1-2 years).

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

    CERN Document Server

    Kataria, Tiffany; Fortney, Jonathan J; Marley, Mark S; Freedman, Richard S

    2014-01-01

    We present three-dimensional atmospheric circulation models of GJ 1214b, a 2.7 Earth-radius, 6.5 Earth-mass super Earth detected by the MEarth survey. Here we explore the planet's circulation as a function of atmospheric metallicity and atmospheric composition, modeling atmospheres with a low mean-molecular weight (i.e., H2-dominated) and a high mean-molecular weight (i.e. water- and CO2-dominated). We find that atmospheres with a low mean-molecular weight have strong day-night temperature variations at pressures above the infrared photosphere that lead to equatorial superrotation. For these atmospheres, the enhancement of atmospheric opacities with increasing metallicity lead to shallower atmospheric heating, larger day-night temperature variations and hence stronger superrotation. In comparison, atmospheres with a high mean-molecular weight have larger day-night and equator-to-pole temperature variations than low mean-molecular weight atmospheres, but differences in opacity structure and energy budget lead ...

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

    Science.gov (United States)

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

    2014-09-02

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

  18. Atmospheric control on isotopic composition and d-excess in water vapor over ocean surface

    Science.gov (United States)

    Fan, Naixin

    For decades, stable isotopes of water have been used as proxies to infer the variation of the hydrological cycle. However, it is still not clear how various atmospheric processes quantitatively control kinetic fractionation during evaporation over the ocean. Understanding kinetic fractionation is important in that the interpretation of the isotopic composition record preserved in ice cores and precipitation relies in part on the isotopic information at the moisture source. In addition, the isotopic composition of vapor contains information about variation of atmospheric processes such as turbulence and change in moisture source region which is useful for studying meteorological processes and climate change. In this study the isotopic composition of water vapor in the marine boundary layer (MBL) over the ocean was investigated using a combination of a newly developed marine boundary layer (MBL) model and observational data. The new model has a more realistic MBL structure than previous models and includes new features such as vertical advection of air and diffusion coefficients that vary continuously in the vertical direction. A robust linear relationship between deltaD and delta18O was found in observational oceanic water vapor data and the model can well capture the characteristics of this relationship. The individual role of atmospheric processes or variables on deltaD, delta18O and d-excess was quantitatively investigated and an overview of the combined effect of all the meteorological processes is provided. In particular, we emphasize that the properties of subsiding air (such as its mixing ratio and isotopic values) are crucial to the isotopic composition of surface water vapor. Relative humidity has been used to represent the moisture deficit that drives evaporative isotopic fluxes, however, we argue that it has serious limitations in explaining d-excess variation as latitude varies. We introduce a new quantity Gd=SST-Td, the difference between the sea

  19. Process-induced compositional changes of flaxseed.

    Science.gov (United States)

    Wanasundara, P K; Shahidi, F

    1998-01-01

    Flaxseed has been used as an edible grain in different parts of the world since ancient times. However, use of flaxseed oil has been limited due to its high content of polyunsaturated fatty acids. Nonetheless, alpha-linolenic acid, dietary fiber and lignans of flaxseed have regained attention. New varieties of flaxseed containing low levels of alpha-linolenic acid are available for edible oil extraction. Use of whole flaxseed in foods provides a means to utilise all of its nutrients and require minimum processing steps. However, the presence of cyanogenic glucosides and diglucosides in the seeds is a concern as they may release cyanide upon hydrolysis. In addition, the polyunsaturated fatty acids may undergo thermal or autooxidation when exposed to air or high temperatures that are used in food preparation. Studies todate on oxidation products of intact flaxseed lipids have not shown any harmful effects when flaxseed is included, up to 28%, in the baked products. Furthermore, cyanide levels produced as a result of autolysis are below the harmful limits to humans. However, the meals left after oil extraction require detoxification but, by solvent extraction, to reduce the harmful effects of cyanide when used in animal rations. Flaxseed meal is a good source of proteins; these could be isolated by complexation with sodium hexametaphosphate without changing their nutritional value or composition. In addition, the effect of germination on proteins, lipids, cyanogenic glycosides, and other minor constituents of flaxseed is discussed.

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

    Science.gov (United States)

    Berner, Robert A

    2003-11-20

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

  1. The influence of vegetation fires on the chemical composition of the atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Helas, H.; Pienaar, J.J. [Max Planck Institute of Chemistry, Mainz (Germany). Biogeochemistry Dept.

    1996-03-01

    The authors discuss the influence of vegetation fires on the chemical composition of the atmosphere and compare the contribution of these fires to atmospheric pollution with other natural and anthropogenic sources. In the case of South Africa, the comparison shows that for CO{sub 2}, NO{sub x} and SO{sub 2}, industrial coal use is the largest contributor whereas for CO and CH{sub 4}, vegetation fires contribute the most. As a source of atmospheric NO{sub x} motor vehicles are more important than emissions from veld fires.

  2. Compositional diversity in the atmospheres of hot Neptunes, with application to GJ 436b

    CERN Document Server

    Moses, Julianne I; Visscher, Channon; Richardson, Molly R; Nettelmann, Nadine; Fortney, Jonathan J; Stevenson, Kevin B; Madhusudhan, Nikku

    2013-01-01

    Neptune-sized extrasolar planets that orbit relatively close to their host stars -- often called "hot Neptunes" -- are common within the known population of exoplanets and planetary candidates. Similar to our own Uranus and Neptune, inefficient accretion of nebular gas is expected produce hot Neptunes whose masses are dominated by elements heavier than hydrogen and helium. At high atmospheric metallicities of 10-10,000x solar, hot Neptunes will exhibit an interesting continuum of atmospheric compositions, ranging from more Neptune-like, H2-dominated atmospheres to more Venus-like, CO2-dominated atmospheres. We explore the predicted equilibrium and disequilibrium chemistry of generic hot Neptunes and find that the atmospheric composition varies strongly as a function of temperature and bulk atmospheric properties such as metallicity and the C/O ratio. Relatively exotic H2O, CO, CO2, and even O2-dominated atmospheres are possible for hot Neptunes. We apply our models to the case of GJ 436b, where we find that a...

  3. CHIMERE 2013: a model for regional atmospheric composition modelling

    Directory of Open Access Journals (Sweden)

    L. Menut

    2013-07-01

    Full Text Available Tropospheric trace gas and aerosol pollutants have adverse effects on health, environment and climate. In order to quantify and mitigate such effects, a wide range of processes leading to the formation and transport of pollutants must be considered, understood and represented in numerical models. Regional scale pollution episodes result from the combination of several factors: high emissions (from anthropogenic or natural sources, stagnant meteorological conditions, kinetics and efficiency of the chemistry and the deposition. All these processes are highly variable in time and space, and their relative contribution to the pollutants budgets can be quantified with chemistry-transport models. The CHIMERE chemistry-transport model is dedicated to regional atmospheric pollution event studies. Since it has now reached a certain level a maturity, the new stable version, CHIMERE 2013, is described to provide a reference model paper. The successive developments of the model are reviewed on the basis of published investigations that are referenced in order to discuss the scientific choices and to provide an overview of the main results.

  4. Sensitivity of biomarkers to changes in chemical emissions in the Earth’s Proterozoic atmosphere

    Science.gov (United States)

    Grenfell, J. L.; Gebauer, S.; von Paris, P.; Godolt, M.; Hedelt, P.; Patzer, A. B. C.; Stracke, B.; Rauer, H.

    2011-01-01

    The search for life beyond the Solar System is a major activity in exoplanet science. However, even if an Earth-like planet were to be found, it is unlikely to be at a similar stage of evolution as the modern Earth. It is therefore of interest to investigate the sensitivity of biomarker signals for life as we know it for an Earth-like planet but at earlier stages of evolution. Here, we assess biomarkers, i.e. species almost exclusively associated with life, in present-day and in 10% present atmospheric level oxygen atmospheres corresponding to the Earth's Proterozoic period. We investigate the impact of proposed enhanced microbial emissions of the biomarker nitrous oxide, which photolyses to form nitrogen oxides which can destroy the biomarker ozone. A major result of our work is regardless of the microbial activity producing nitrous oxide in the early anoxic ocean, a certain minimum ozone column can be expected to persist in Proterozoic-type atmospheres due to a stabilising feedback loop between ozone, nitrous oxide and the ultraviolet radiation field. Atmospheric nitrous oxide columns were enhanced by a factor of 51 for the Proterozoic "Canfield ocean" scenario with 100 times increased nitrous oxide surface emissions. In such a scenario nitrous oxide displays prominent spectral features, so may be more important as a biomarker than previously considered in such cases. The run with "Canfield ocean" nitrous oxide emissions enhanced by a factor of 100 also featured additional surface warming of 3.5 K. Our results suggest that the Proterozoic ozone layer mostly survives the changes in composition which implies that it is indeed a good atmospheric biomarker.

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

    Science.gov (United States)

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

    2010-08-01

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

  6. Color change of composite resins subjected to accelerated artificial aging

    Directory of Open Access Journals (Sweden)

    Denise Cremonezzi Tornavoi

    2013-01-01

    Conclusions: All composite resins presented unacceptable color changes after 382 h of aging and different composite resins with same hue, presented different colors before being subjected to the aging process (B2 and C2 and after (B2. It was also observed color difference within a group of the same composite resin and same hue.

  7. Achilles tendinosis: Changes in biochemical composition and collagen turnover rate

    NARCIS (Netherlands)

    Mos, M. de; El, B. van; Groot, J. de; Jahr, H.; Schie, H.T.M. van; Arkel, E.R. van; Tol, H.; Heijboer, R.; Osch, G.J.V.M. van; Verhaar, J.A.N.

    2007-01-01

    Background: Understanding biochemical and structural changes of the extracellular matrix in Achilles tendinosis might be important for developing mechanism-based therapies. Hypothesis: In Achilles tendinosis, changes occur in biochemical composition and collagen turnover rate. Study Design: Descript

  8. Achilles tendinosis - Changes in biochemical composition and collagen turnover rate

    NARCIS (Netherlands)

    de Mos, Marieke; van El, Benno; DeGroot, Jeroen; Jahr, Holger; van Schie, Hans T. M.; van Arkel, Ewoud R.; Tol, Hans; Heijboer, Rien; van Osch, Gerjo J. V. M.; Verhaar, Jan A. N.

    2007-01-01

    Background: Understanding biochemical and structural changes of the extracellular matrix in Achilles tendinosis might be important for developing mechanism-based therapies. Hypothesis: In Achilles tendinosis, changes occur in biochemical composition and collagen turnover rate. Study Design: Descript

  9. Effects of photorespiration, the cytochrome pathway, and the alternative pathway on the triple isotopic composition of atmospheric O2

    Science.gov (United States)

    Angert, Alon; Rachmilevitch, Shimon; Barkan, Eugeni; Luz, Boaz

    2003-03-01

    The triple isotopic composition of atmospheric O2 is a new tracer used to estimate changes in global productivity. To estimate such changes, knowledge of the relationship between the discrimination against 17O and the discrimination against 18O is needed. This relationship is presented as θ = ln(17α)/ln(18α). Here, the value of theta was evaluated for the most important processes that affect the isotopic composition of oxygen. Similar values were found for dark respiration through the cytochrome pathway (0.516 ± 0.001) and the alternative pathway (0.514 ± 0.001), and slightly higher value was found for diffusion in air (0.521 ± 0.001). The combined effect of diffusion and respiration on the atmosphere was shown to be close to that of dark respiration. The value we found for photorespiration (0.506 ± 0.005) is considerably lower than that of dark respiration. Our results clearly show that the triple isotopic composition of the atmosphere is affected by the relative rates of photorespiration and dark respiration. Also, we show that closing the current global isotopic balance will enable the estimation of the current global rate of photorespiration. Using the Last Glacial Maximum as a case study, we show that variations in global rate of photorespiration affected the triple isotopic composition in the past. Strong fractionations measured in illuminated plants indicated that the alternative pathway is activated in the same conditions that favor high rate of photorespiration. This activation suggests that the global rate of the alternative pathway is higher than believed thus far, and may help to close the gap between the calculated and measured Dole Effect.

  10. Chemical composition of atmospheric aerosols between Moscow and Vladivostok

    Directory of Open Access Journals (Sweden)

    S. Kuokka

    2007-05-01

    Full Text Available The TROICA-9 expedition (Trans-Siberian Observations Into the Chemistry of the Atmosphere was carried out at the Trans-Siberian railway between Moscow and Vladivostok in October 2005. Measurements of aerosol physical and chemical properties were made from an observatory carriage connected to a passenger train. Black carbon (BC concentrations in fine particles (PM2.5, aerodynamic diameter <2.5 μm were measured with an aethalometer using a five-minute time resolution. Concentrations of inorganic ions and some organic compounds (Cl, NO3, SO42−, Na+, NH4+, K+, Ca2+, Mg2+, oxalate and methane sulphonate were measured continuously by using an on-line system with a 15-min time resolution. In addition, particle volume size distributions were determined for particles in the diameter range 3–850 nm using a 10-min. time resolution. The continuous measurements were completed with 24-h. PM2.5 filter samples which were stored in a refrigerator and later analyzed in chemical laboratory. The analyses included mass concentrations of PM2.5, ions, monosaccharide anhydrides (levoglucosan, galactosan and mannosan and trace elements (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sb, V and Zn. The mass concentrations of PM2.5 varied in the range of 4.3–34.8 μg m−3 with an average of 21.6 μg m−3. Fine particle mass consisted mainly of BC (average 27.6%, SO42− (13.0%, NH4+ (4.1%, and NO3 (1.4%. One of the major constituents was obviously also organic carbon which was not determined. The contribution of BC was high compared with other studies made in Europe and Asia. High concentrations of ions, BC and particle volume were observed between Moscow and roughly 4000 km east of it, as well as close to

  11. A comparison of atmospheric composition using the Carbon Bond and Regional Atmospheric Chemistry Mechanisms

    Directory of Open Access Journals (Sweden)

    G. Sarwar

    2013-03-01

    Full Text Available 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, RACM2 enhances the domain-wide monthly mean hydroxyl radical concentrations by 46% and nitric acid by 26%. However, it reduces hydrogen peroxide by 2%, peroxyacetic acid by 94%, methyl hydrogen peroxide by 19%, peroxyacetyl nitrate by 40%, and organic nitrate by 41%. RACM2 predictions generally agree better with the observed data than the CB05TU predictions. RACM2 enhances ozone for all ambient levels leading to higher bias at low (70 ppbv concentrations. The RACM2 ozone predictions are also supported by increased ozone production efficiency that agrees better with observations. Compared to CB05TU, RACM2 enhances the domain-wide monthly mean sulfate by 10%, nitrate by 6%, ammonium by 10%, anthropogenic secondary organic aerosols by 42%, biogenic secondary organic aerosols by 5%, and in-cloud secondary organic aerosols by 7%. Increased inorganic and organic aerosols with RACM2 agree better with observed data. While RACM2 enhances ozone and secondary aerosols by relatively large margins, control strategies developed for ozone or fine particles using the two mechanisms do not differ appreciably.

  12. A comparison of atmospheric composition using the Carbon Bond and Regional Atmospheric Chemistry Mechanisms

    Directory of Open Access Journals (Sweden)

    G. Sarwar

    2013-10-01

    Full Text Available 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, RACM2 enhances the domain-wide monthly mean hydroxyl radical concentrations by 46% and nitric acid by 26%. However, it reduces hydrogen peroxide by 2%, peroxyacetic acid by 94%, methyl hydrogen peroxide by 19%, peroxyacetyl nitrate by 40%, and organic nitrate by 41%. RACM2 enhances ozone compared to CB05TU at all ambient levels. Although it exhibited greater overestimates at lower observed concentrations, it displayed an improved performance at higher observed concentrations. The RACM2 ozone predictions are also supported by increased ozone production efficiency that agrees better with observations. Compared to CB05TU, RACM2 enhances the domain-wide monthly mean sulfate by 10%, nitrate by 6%, ammonium by 10%, anthropogenic secondary organic aerosols by 42%, biogenic secondary organic aerosols by 5%, and in-cloud secondary organic aerosols by 7%. Increased inorganic and organic aerosols with RACM2 agree better with observed data. Any air pollution control strategies developed using the two mechanisms do not differ appreciably.

  13. Spectral analysis of atmospheric composition: application to surface ozone model-measurement comparisons

    Science.gov (United States)

    Bowdalo, Dene R.; Evans, Mathew J.; Sofen, Eric D.

    2016-07-01

    Models of atmospheric composition play an essential role in our scientific understanding of atmospheric processes and in providing policy strategies to deal with societally relevant problems such as climate change, air quality, and ecosystem degradation. The fidelity of these models needs to be assessed against observations to ensure that errors in model formulations are found and that model limitations are understood. A range of approaches are necessary for these comparisons. Here, we apply a spectral analysis methodology for this comparison. We use the Lomb-Scargle periodogram, a method similar to a Fourier transform, but better suited to deal with the gapped data sets typical of observational data. We apply this methodology to long-term hourly ozone observations and the equivalent model (GEOS-Chem) output. We show that the spectrally transformed observational data show a distinct power spectrum with regimes indicative of meteorological processes (weather, macroweather) and specific peaks observed at the daily and annual timescales together with corresponding harmonic peaks at one-half, one-third, etc., of these frequencies. Model output shows corresponding features. A comparison between the amplitude and phase of these peaks introduces a new comparison methodology between model and measurements. We focus on the amplitude and phase of diurnal and seasonal cycles and present observational/model comparisons and discuss model performance. We find large biases notably for the seasonal cycle in the mid-latitude Northern Hemisphere where the amplitudes are generally overestimated by up to 16 ppbv, and phases are too late on the order of 1-5 months. This spectral methodology can be applied to a range of model-measurement applications and is highly suitable for Multimodel Intercomparison Projects (MIPs).

  14. Chemical composition of aerosol in the atmospheric surface layer of the East Antarctica coastal zone

    Directory of Open Access Journals (Sweden)

    L. P. Golobokova

    2016-01-01

    Full Text Available Chemical composition of aerosol in the ground layer of the coastal zone in East Antarctica is analyzed in the article. The aerosol samples were taken in 2006–2015 during seasonal works of the Russian Antarctic Expeditions (RAE, namely, these were 52nd–53rd, 55th, and 58th–60th expeditions. Samples were taken in the 200‑km band of the sea-shore zone along routes of the research vessels (REV «Akademik Fedorov» and «Akademik Treshnikov» as well as on territories of the Russian stations Molodezhnaya and Mirny. Although the results obtained did show the wide range of the aerosol concentrations and a certain variability of their chemical composition, some common features of the variability were revealed. Thus, during the period from 2006 to 2014 a decrease of average values of the sums were noted. Spatially, a tendency of decreasing of the ion concentrations was found in the direction from the station Novolazarevskaya to the Molodezhnaya one, but the concentrations increased from the Molodezhnaya to the station Mirny. The sum of ions of the aerosol in the above mentioned coastal zone was, on the average, equal to 2.44 μg/m3, and it was larger than that on the territory of the Antarctic stations Molodezhnaya (0,29 μg/m3 and Mirny (0,50 ág / m3. The main part to the sum of the aerosol ions on the Antarctic stations was contributed by Na+, Ca2+, Cl−, SO4 2−. The main ions in aerosol composition in the coastal zone are ions Na+ and Cl−. The dominant contribution of the sea salt and SO4 2− can be traced in not only the composition of atmospheric aerosols, but also in the chemical composition of the fresh snow in the coastal areas of East Antarctica: at the Indian station Maitri, on the Larsemann Hills, and in a boring located in 55.3 km from the station Progress (K = 1.4÷6.1. It was noted that values of the coefficient of enrichment K of these ions decreases as someone moves from a shore to inland. Estimation of

  15. Global change induced trends in ion composition of the troposphere to the lower thermosphere

    Directory of Open Access Journals (Sweden)

    G. Beig

    2008-05-01

    Full Text Available In this paper a brief overview of the changes in atmospheric ion compositions driven by the human-induced changes in related neutral species, and temperature from the troposphere to lower thermosphere has been made. It is found that ionic compositions undergo significant variations. The variations calculated for the double-CO2 scenario are both long-term and permanent in nature. Major neutrals which take part in the lower and middle atmospheric ion chemical schemes and undergo significant changes due to anthropogenic activities are: O, O2, H2O, NO, acetonitrile, pyridinated compounds, acetone and aerosol. The concentration of positive ion/electron density does not change appreciably in the middle atmosphere but indicates a marginal decrease above about 75 km until about 85 km, above which the magnitude of negative trend decreases and becomes negligible at 93 km. Acetonitrile cluster ions in the upper stratosphere are likely to increase, whereas NO+ and NO+(H2O in the mesosphere and lower thermosphere (MLT region are expected to decrease for the double CO2 scenario. It is also found that the atmospheric density of pyridinated cluster ions is fast rising in the troposphere.

  16. Sulfur isotopic composition and source identification of atmospheric environment in central Zhejiang,China

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Sulfur dioxide and sulfate aerosols in the atmosphere are significant factors leading to acidification of the atmospheric environment and worsening the pollution of acid deposition. Because of the "fingerprint" characteristics of the stable sulfur isotopic composition, sulfur isotope has been widely adopted in environmental researches concerning sulfur cycle and source identification. In this study, the atmospheric environment of Jinhua City, central Zhejiang Province, was continuously monitored, and the sulfur isotopic composition of SO2 and sulfate aerosols in the atmosphere was analyzed. The results indicate that the variation of δ34S values for SO2 ranges from 1.0‰ to 7.5‰, and annual average is 4.7‰±2.3‰, whereas that of sulfate aerosols ranges from 6.4‰ to 9.8‰,and annual average is 8.1‰±1.0‰. The δ 34S values for SO2 have significant seasonal variations, which are 7.0‰ in winter and 3.3‰ in summer. These variations cannot be attributed to a single factor, and we suggest a temperature-dependent isotope equilibrium fractionation and elevated biogenic sulfur emissions of isotopically light S in summer may be the main controlling mechanisms. Furthermore, we also discuss the δ 34S model of atmospheric SO2 oxidation to form sulfate, and suggest that heterogeneous oxidation dominates in the oxidation reactions of atmospheric SO2 in the central Zhejiang Province. We further suggest that the relative humidity in the atmosphere plays an important role in the oxidation mechanism of atmospheric SO2.

  17. Land-Atmosphere Interactions in Cold Environments (LATICE): The role of Atmosphere - Biosphere - Cryosphere - Hydrosphere interactions in a changing climate

    Science.gov (United States)

    Burkhart, J. F.; Tallaksen, L. M.; Stordal, F.; Berntsen, T.; Westermann, S.; Kristjansson, J. E.; Etzelmuller, B.; Hagen, J. O.; Schuler, T.; Hamran, S. E.; Lande, T. S.; Bryn, A.

    2015-12-01

    Climate change is impacting the high latitudes more rapidly and significantly than any other region of the Earth because of feedback processes between the atmosphere and the underlying surface. A warmer climate has already led to thawing of permafrost, reducing snow cover and a longer growing season; changes, which in turn influence the atmospheric circulation and the hydrological cycle. Still, many studies rely on one-way coupling between the atmosphere and the land surface, thereby neglecting important interactions and feedbacks. The observation, understanding and prediction of such processes from local to regional and global scales, represent a major scientific challenge that requires multidisciplinary scientific effort. The successful integration of earth observations (remote and in-situ data) and model development requires a harmonized research effort between earth system scientists, modelers and the developers of technologies and sensors. LATICE, which is recognized as a priority research area by the Faculty of Mathematics and Natural Sciences at the University of Oslo, aims to advance the knowledge base concerning land atmosphere interactions and their role in controlling climate variability and climate change at high northern latitudes. The consortium consists of an interdisciplinary team of experts from the atmospheric and terrestrial (hydrosphere, cryosphere and biosphere) research groups, together with key expertise on earth observations and novel sensor technologies. LATICE addresses critical knowledge gaps in the current climate assessment capacity through: Improving parameterizations of processes in earth system models controlling the interactions and feedbacks between the land (snow, ice, permafrost, soil and vegetation) and the atmosphere at high latitudes, including the boreal, alpine and artic zone. Assessing the influence of climate and land cover changes on water and energy fluxes. Integrating remote earth observations with in-situ data and

  18. Phanerozoic atmospheric CO 2 change: evaluating geochemical and paleobiological approaches

    Science.gov (United States)

    Royer, Dana L.; Berner, Robert A.; Beerling, David J.

    2001-08-01

    The theory and use of geochemical modeling of the long-term carbon cycle and four paleo-PCO 2 proxies are reviewed and discussed in order to discern the best applications for each method. Geochemical models provide PCO 2 predictions for the entire Phanerozoic, but most existing models present 5-10 m.y. means, and so often do not resolve short-term excursions. Error estimates based on sensitivity analyses range from ±75-200 ppmV for the Tertiary to as much as ±3000 ppmV during the early Paleozoic. The δ13C of pedogenic carbonates provide the best proxy-based PCO 2 estimates for the pre-Tertiary, with error estimates ranging from ±500-1000 ppmV. Pre-Devonian estimates should be treated cautiously. Error estimates for Tertiary reconstructions via this proxy are higher than other proxies and models (±400-500 ppmV), and should not be solely relied upon. We also show the importance of measuring the δ13C of coexisting organic matter instead of inferring its value from marine carbonates. The δ13C of the organic remains of phytoplankton from sediment cores provide high temporal resolution (up to 10 3-10 4 year), high precision (±25-100 ppmV for the Tertiary to ±150-200 ppmV for the Cretaceous) PCO 2 estimates that can be near continuous for most of the Tertiary. Its high temporal resolution and availability of continuous sequences is advantageous for studies aiming to discern short-term excursions. This method, however, must correct for changes in growth rate and oxygen level. At elevated PCO 2 (˜750-1250 ppmV), this proxy loses its sensitivity and is not useful. The stomatal density and stomatal index of land plants also provide high temporal resolution (level of PCO 2 above 350 ppmV (which, currently, is largely undetermined). Our analysis of the recently developed δ11B technique shows that it currently is not yet well constrained. Most importantly, it requires the assumption that the boron isotopic composition of the ocean remains nearly constant through time

  19. Recent laboratory and field observations of the chemical composition of atmospheric nanoparticles

    Science.gov (United States)

    Smith, J. N.; Winkler, P.; Hildebrandt Ruiz, L.; Lawler, M. J.; Ortega, J.; Fry, J.; Barsanti, K. C.; McMurry, P. H.; Johnston, M. V.

    2012-12-01

    This presentation will focus on understanding the species and mechanisms that are responsible for the formation and growth of atmospheric nanoparticles. We report 10 - 40 nm diameter nanoparticle chemical composition measurements performed in two coastal sites (Mace Head, Ireland, and Lewes, Delaware USA) and two forested sites (Hyytiälä, Finland, and Manitou Forest, Colorado USA) with the recently-developed High Resolution Time-of-Flight Thermal Desorption Chemical Ionization Mass Spectrometer (HTOF-TDCIMS). These field measurements are supplemented by laboratory experiments of particle formation and growth performed at NCAR using a flow tube apparatus and a Teflon bag reaction chamber, and by thermodynamic modeling. Together, our field and laboratory observations point to crucial roles played in nanoparticle growth by two compounds: organic acids and organonitrates. The first, organic acids, are major contributors to the organic fraction in sub-20 nm diameter biogenic nanoparticles but appear to be less abundant in the organic fraction of larger particles, the latter of which are dominated by multifunctional carbonyl- and alcohol-containing compounds. The observed changes in chemical composition of the organic fraction as a function of particle size are supported by thermodynamic modeling results. The second, organonitrates, are commonly found in ambient nanoparticles as small as 10 nm in diameter. However unlike organic acids, organonitrates become increasingly more important in nanoparticle growth as particle size increases. Laboratory experiments suggest that organonitrates formed from the nitrate radical oxidation of biogenic organic compounds, a subset of total organonitrates, exhibit particularly low volatility and can thus partition into the smallest nanoparticles. This is confirmed by HTOF-TDCIMS measurements of 10 - 20 nm diameter particles, which show that particulate phase organonitrates peak in the morning, shortly following the period where

  20. Composition and effects of inhalable size fractions of atmospheric aerosols in the polluted atmosphere: part I. PAHs, PCBs and OCPs and the matrix chemical composition.

    Science.gov (United States)

    Landlová, Linda; Cupr, Pavel; Franců, Juraj; Klánová, Jana; Lammel, Gerhard

    2014-05-01

    Atmospheric particulate matter (PM) abundance, mass size distribution (MSD) and chemical composition are parameters relevant for human health effects. The MSD and phase state of semivolatile organic pollutants were determined at various polluted sites in addition to the PM composition and MSD. The distribution pattern of pollutants varied from side to side in correspondence to main particle sources and PM composition. Levels of particle-associated polycyclic aromatic hydrocarbons (PAHs) were 1-30 ng m(-3) (corresponding to 15-35 % of the total, i.e., gas and particulate phase concentrations), of polychlorinated biphenyls (PCBs) were 2-11 pg m(-3) (4-26 % of the total) and of DDT compounds were 2-12 pg m(-3) (4-23 % of the total). The PM associated amounts of other organochlorine pesticides were too low for quantification. The organics were preferentially found associated with particles matrix composition, amount of contaminants and toxicological effects occur. Legislative regulation based on gravimetric determination of PM mass can clearly be insufficient for assessment.

  1. THE INFLUENCE OF THE EXTREME ULTRAVIOLET SPECTRAL ENERGY DISTRIBUTION ON THE STRUCTURE AND COMPOSITION OF THE UPPER ATMOSPHERE OF EXOPLANETS

    Energy Technology Data Exchange (ETDEWEB)

    Guo, J. H. [Yunnan Observatories, Chinese Academy of Sciences, P.O. Box 110, Kunming 650011 (China); Ben-Jaffel, Lotfi, E-mail: guojh@ynao.ac.cn, E-mail: bjaffel@iap.fr [Sorbonne Universités, UPMC Univ. Paris 6 et CNRS, UMR 7095, Institut Astrophysique de Paris, F-75014 Paris (France)

    2016-02-20

    By varying the profiles of stellar extreme ultraviolet (EUV) spectral energy distributions (SEDs), we tested the influences of stellar EUV SEDs on the physical and chemical properties of an escaping atmosphere. We apply our model to study four exoplanets: HD 189733b, HD 209458b, GJ 436b, and Kepler-11b. We find that the total mass loss rates of an exoplanet, which are determined mainly by the integrated fluxes, are moderately affected by the profiles of the EUV SED, but the composition and species distributions in the atmosphere can be dramatically modified by the different profiles of the EUV SED. For exoplanets with a high hydrodynamic escape parameter (λ), the amount of atomic hydrogen produced by photoionization at different altitudes can vary by one to two orders of magnitude with the variation of stellar EUV SEDs. The effect of photoionization of H is prominent when the EUV SED is dominated by the low-energy spectral region (400–900 Å), which pushes the transition of H/H{sup +} to low altitudes. In contrast, the transition of H/H{sup +} moves to higher altitudes when most photons are concentrated in the high-energy spectral region (50–400 Å). For exoplanets with a low λ, the lower temperatures of the atmosphere make many chemical reactions so important that photoionization alone can no longer determine the composition of the escaping atmosphere. For HD 189733b, it is possible to explain the time variability of Lyα between 2010 and 2011 by a change in the EUV SED of the host K-type star, yet invoking only thermal H i in the atmosphere.

  2. Effects of Bulk Composition on The Atmospheric Dynamics on Close-in Exoplanets

    CERN Document Server

    Zhang, Xi

    2016-01-01

    Super Earths and mini Neptunes likely have a wide range of atmospheric compositions, such as H2, H2O, N2, and CO2. Here, we systematically investigate the effects of atmospheric bulk compositions on temperature and wind distributions for tidally locked sub-Jupiter-sized planets, using an idealized three-dimensional general circulation model (GCM). The bulk composition effects are characterized in the framework of two independent variables: molecular weight and molar heat capacity. The effect of molecular weight dominates. As the molecular weight increases, the atmosphere tends to have a larger day-night temperature contrast, a smaller eastward phase shift in the thermal phase curve and a smaller zonal wind speed. The width of the equatorial super-rotating jet also becomes narrower and the "jet core" region, where the zonal-mean jet speed maximizes, moves to a greater pressure level. The zonal-mean zonal wind is more prone to exhibit a latitudinally alternating pattern in a higher-molecular weight atmosphere. ...

  3. Attaining the Steady State of the Nitriding Potential after a Change of NH3 Atmosphere Flow Rate during the Gas Nitriding Process

    Institute of Scientific and Technical Information of China (English)

    Jerzy Michalski; Jan Tacikowski; Piotr Wach; Tomasz Babul; Nabil Tarfa

    2004-01-01

    In single and multi-stage nitriding processes, each stage is characterized by the following parameters:temperature and time, type and composition of incoming atmosphere, as well as the set value of the nitriding potential. In the case of an atmosphere composed of raw ammonia and dissociated ammonia (NH3- NH3diss), the set value of the nitriding potential can be achieved by a change of the incoming atmosphere make-up, while in the case of atmospheres comprising NH3 and NH3 - N2 - by a change of the atmosphere flow rate. The time needed to reach a stabilized state, after the initiation of a change in the atmosphere gas mix can be assessed relatively easily. The problem is much more complex if we want to predict the time of reaching a new stabilized state following a change in atmosphere flow rate. The time of reaching stabilized state is, in this case, a complex function of the flow rate of the atmosphere which forces the potential change, and of temperature. This problem, in the case of the NH3 type atmosphere, is the subject of investigation in this work. Factors are discussed, affecting the rate at which stabilized state is reached by the system after the introduction of a disturbance, necessary to attain the required nitriding potential.

  4. Abundance and Isotopic Composition of Gases in the Martian Atmosphere: First Results from the Mars Curiosity Rover

    Science.gov (United States)

    Mahaffy, Paul; Webster, Chris R.; Atreya, Sushil K.; Franz, Heather; Wong, Michael; Conrad, Pamela G.; Harpold, Dan; Jones, John J.; Leshin, Laurie, A.; Manning, Heidi; Owen, Tobias; Pepin, Robert O.; Squyres, Steven; Trainer, Melissa

    2013-01-01

    Repeated measurements of the composition of the Mars atmosphere from Curiosity Rover yield a (40)Ar/N2 ratio 1.7 times greater and the (40)Ar/(36)Ar ratio 1.6 times smaller than the Viking Lander values in 1976. The unexpected change in (40)Ar/N2 ratio probably results from different instrument characteristics although we cannot yet rule out some unknown atmospheric process. The new (40)Ar/(36)Ar ratio is more aligned with Martian meteoritic values. Besides Ar and N2 the Sample Analysis at Mars instrument suite on the Curiosity Rover has measured the other principal components of the atmosphere and the isotopes. The resulting volume mixing ratios are: CO2 0.960(+/- 0.007); (40)Ar 0.0193(+/- 0.0001); N2 0.0189(+/- 0.0003); O2 1.45(+/- 0.09) x 10(exp -3); and CO 5.45(+/- 3.62) x 10(exp 4); and the isotopes (40)Ar/(36)Ar 1.9(+/- 0.3) x 10(exp 3), and delta (13)C and delta (18)O from CO2 that are both several tens of per mil more positive than the terrestrial averages. Heavy isotope enrichments support the hypothesis of large atmospheric loss. Moreover, the data are consistent with values measured in Martian meteorites, providing additional strong support for a Martian origin for these rocks.

  5. The response of atmospheric CO sub 2 to changes in land use

    Energy Technology Data Exchange (ETDEWEB)

    King, A.W.; Emanuel, W.R.; Post, W.M.

    1990-01-01

    The burning of biomass that often accompanies deforestation and other changes in land use is believed to be a major contributor to documented increases in the concentration of atmospheric CO{sub 2}. Using three models of carbon turnover in the atmosphere and ocean, we simulate changes in atmospheric CO{sub 2} that result from the addition of CO{sub 2} from industrial sources and terrestrial ecosystems disturbed by changes in land use. We simulate atmospheric response to different histories of terrestrial biospheric CO{sub 2} release, and we compare these simulations with the history of atmospheric CO{sub 2} obtained from ice core measurements and atmospheric monitoring stations. 63 refs., 12 figs., 1 tab.

  6. Response of global soil consumption of atmospheric methane to changes in atmospheric climate and nitrogen deposition

    Science.gov (United States)

    Zhuang, Qianlai; Chen, Min; Xu, Kai; Tang, Jinyun; Saikawa, Eri; Lu, Yanyu; Melillo, Jerry M.; Prinn, Ronald G.; McGuire, A. David

    2013-01-01

    Soil consumption of atmospheric methane plays an important secondary role in regulating the atmospheric CH4 budget, next to the dominant loss mechanism involving reaction with the hydroxyl radical (OH). Here we used a process-based biogeochemistry model to quantify soil consumption during the 20th and 21st centuries. We estimated that global soils consumed 32–36 Tg CH4 yr−1 during the 1990s. Natural ecosystems accounted for 84% of the total consumption, and agricultural ecosystems only consumed 5 Tg CH4 yr−1 in our estimations. During the twentieth century, the consumption rates increased at 0.03–0.20 Tg CH4 yr−2 with seasonal amplitudes increasing from 1.44 to 3.13 Tg CH4 month−1. Deserts, shrublands, and xeric woodlands were the largest sinks. Atmospheric CH4 concentrations and soil moisture exerted significant effects on the soil consumption while nitrogen deposition had a moderate effect. During the 21st century, the consumption is predicted to increase at 0.05-1.0 Tg CH4 yr−2, and total consumption will reach 45–140 Tg CH4 yr−1 at the end of the 2090s, varying under different future climate scenarios. Dry areas will persist as sinks, boreal ecosystems will become stronger sinks, mainly due to increasing soil temperatures. Nitrogen deposition will modestly reduce the future sink strength at the global scale. When we incorporated the estimated global soil consumption into our chemical transport model simulations, we found that nitrogen deposition suppressed the total methane sink by 26 Tg during the period 1998–2004, resulting in 6.6 ppb higher atmospheric CH4 mixing ratios compared to without considering nitrogen deposition effects. On average, a cumulative increase of every 1 Tg soil CH4 consumption decreased atmospheric CH4 mixing ratios by 0.26 ppb during the period 1998–2004.

  7. The Triple Isotopic Composition of Atmospheric O2 as a Tracer of the Rate of Global Photorespiration

    Science.gov (United States)

    Angert, A.; Luz, B.; Barkan, E.; Rachmilevitch, S.

    2001-12-01

    The triple isotopic composition of atmospheric O2 is controlled by different signatures of biological and stratospheric processes. Ultraviolet induced interactions in the stratosphere cause an equal depletion of 17O and 18O of atmospheric O2 (mass-independent fractionation). This equal lowering is in contrast to biological processes, and most terrestrial processes, in which the discrimination against 17O is about half of the discrimination against 18O relative to 16O (mass-dependent fractionation). Thus, O2 that was produced by photosynthesis and was affected only by biological consumption will have excess 17O relatively to atmospheric O2 with the same delta 18O. In previous interpretations of changes in the triple isotopic composition, it was assumed that the ratio of discrimination against 17O to the discrimination against 18O is identical for all biological processes. In the present study, we evaluated this ratio, for the first time, for some of the most important oxygen consumption processes: The cytochrome and alternative pathways of dark respiration, and photorespiration. The value for the dark respiration processes was evaluated in dark incubation experiments, and inhibitors were used to separate the two pathways. The value for photorespiration was evaluated from experiments in airtight terrarium containing soil, plant and water. We have found similar discrimination ratio for the cytochrome and alternative pathways, but considerably lower ratio for photorespiration. One important conclusion derived from this finding is that much of the change in the atmospheric 17O depletion during the LGM can be related to an increase in the global rate of photorespiration. The increased rate of photorespiration during the LGM was the result of lower atmospheric CO2 concentrations. Previous interpretations of the 17O depletion change in the LGM attributed it only to changes in global productivity, and in stratospheric processes. Another important conclusion is that the

  8. INMS-derived composition of Titan's upper atmosphere: Analysis methods and model comparison

    Science.gov (United States)

    Magee, Brian A.; Waite, J. Hunter; Mandt, Kathleen E.; Westlake, Joseph; Bell, Jared; Gell, David A.

    2009-12-01

    The Cassini Ion and Neutral Mass Spectrometer (INMS) has recorded full altitude profile data from 20 low-altitude Titan encounters during the nominal mission (July 2004-2008). These encounters were TA, T5, T16, T18, T19, T21, T23, T25, T26, T28, T29, T30, T32, T36, T37, T39, T40, T41, T42, and T43. In this work we present an analysis of the data observed by INMS during these encounters to derive the neutral composition of Titan's upper atmosphere between 1000 and 1100 km. Analysis methods are described for the determination and correction of instrument effects as well as the composition derivation processes. Results are compared to independent INMS analysis efforts and a selected survey of photochemical models of Titan's upper atmosphere.

  9. Thermal structure, composition, atmospheric dynamics and long-term evolution of irradiated exoplanets

    Science.gov (United States)

    Parmentier, Vivien

    2014-06-01

    More than a thousand exoplanets have been discovered over the last decade. Perhaps more excitingly, probing their atmospheres has become possible. We now have spectra of hot Jupiters like HD 189733b and HD 209458b, of Neptune-like planets like GJ1214b and even smaller planets are within reach. Most exoplanet atmospheric observations are averaged spatially, often over a hemi- sphere (during secondary eclipse) or over the limb of the planet (during transit). For favorable targets, longitudinal and latitudinal resolution can also be obtained with phase curve and secondary eclipse mapping techniques respectively. The closer the planet orbits to its star, the easier it is to observe. These hot planets strongly differ from the examples we have in our solar-system. Proper models of their atmospheres are challenging yet necessary to understand current and future observations. In this thesis, I use a hierarchy of atmospheric models to understand the interactions between the thermal structure, the composition, the atmospheric circulation and the long-term evolution of irradiated planets. In these planets, the large stellar irradiation dominates the energy budget of the atmosphere. It powers a strong atmospheric circulation that transports heat and material around the planet, driving the atmosphere out of thermal and chemical equilibrium and affecting its long-term evolution. Future instruments (Gaia, SPIRou, CHEOPS, TESS, PLATO etc) will discover many more planets that the next generation of telescopes (GMT, TMT, E-ELT or JWST) will characterize with an unprecedented accuracy. Models will be tested on a large sample of planets, extending the study of climates to exoplanets.

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

    Science.gov (United States)

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

    2016-04-01

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

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

    Science.gov (United States)

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

    2016-11-01

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

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

    Science.gov (United States)

    Oman, Luke D.; Strahan, Susan E.

    2016-01-01

    Simulations using reanalyzed meteorological conditions have been long used to understand causes of atmospheric composition change over the recent past. Using the new Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA-2) meteorology, chemistry simulations are being conducted 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 developed 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 analysis. The GMI CTM is a 1 x 1.25 simulation and the MERRA-2 GMI Replay simulation uses the native MERRA-2 approximately horizontal resolution on the cubed sphere. The Replay simulations is driven by the online use of key MERRA-2 meteorological variables (i.e. U, V, T, and surface pressure) with all other variables calculated in response to those variables. A specialized set of transport diagnostics is included in both runs to better understand trace gas transport and changes over the recent past.

  13. Effect of incubation atmosphere on the production and composition of staphylococcal biofilms.

    Science.gov (United States)

    Asai, Kentaro; Yamada, Keiko; Yagi, Tetsuya; Baba, Hisashi; Kawamura, Ichiro; Ohta, Michio

    2015-01-01

    Staphylococcus aureus and Staphylococcus epidermidis are pathogenic bacteria that often cause invasive infections in humans. In this study, we characterized the composition and growth characteristics of staphylococcal biofilms under various incubation atmospheres. We assessed the effect of incubation atmosphere (aerobic, 5% CO2, anaerobic, and microaerobic) on the biofilm production capabilities of S. aureus strains isolated from healthy volunteers and from patients with catheter-related bloodstream infection. In addition, the composition of S. aureus and S. epidermidis biofilms was determined by assessment of biofilm degradation after treatment with DNase I, proteinase K, and dispersin B. The strains obtained from healthy volunteers and patients showed similar biofilm formation capabilities. Biofilms of S. aureus were rich in proteins when developed under ambient atmospheric conditions, 5% CO2, and microaerobic condition, whereas S. epidermidis biofilms contained large amounts of poly-β (1, 6)-N-acetyl-D-glucosamine when developed under ambient atmospheric conditions and microaerobic condition. The biofilm-producing capability of S. epidermidis was considerably higher than that of S. aureus under aerobic condition. Staphylococcal isolates obtained from healthy individuals and patients with catheter-related infections have similar biofilm-forming capabilities. Under microaerobic conditions, S. aureus and S. epidermidis form protein-rich and poly-β (1, 6)-N-acetyl-D-glucosamine-rich biofilms, respectively. These components may play an important role in the development of biofilms inside the body and may be the target molecules to prevent catheter-related infections caused by these organisms.

  14. Flavor Changing Neutral Currents in a Realistic Composite Technicolor Model

    CERN Document Server

    Carone, C D; Carone, Christopher D.; Hamilton, Rowan T.

    1993-01-01

    We consider the phenomenology of a composite technicolor model proposed recently by Georgi. Composite technicolor interactions produce four-quark operators in the low energy theory that contribute to flavor changing neutral current processes. While we expect operators of this type to be induced at the compositeness scale by the flavor-symmetry breaking effects of the preon mass matrices, the Georgi model also includes operators from higher scales that are not GIM-suppressed. Since these operators are potentially large, we study their impact on flavor changing neutral currents and CP violation in the neutral $B$, $D$, and $K$ meson systems.

  15. ORACLE: a module for the description of ORganic Aerosol Composition and Evolution in the atmosphere

    Directory of Open Access Journals (Sweden)

    A. P. Tsimpidi

    2014-08-01

    Full Text Available A computationally efficient module for the description of organic aerosol (OA partitioning and chemical aging has been developed and implemented into the EMAC atmospheric chemistry-climate model. The model simulates the formation of secondary organic aerosol (SOA from semi-volatile (SVOCs, intermediate-volatility (IVOCs and volatile organic compounds (VOCs. The model distinguishes SVOCs from biomass burning and all other combustion sources using two surrogate species for each source category with an effective saturation concentration at 298 K of C* = 0.1 and 10 μg m−3. Two additional surrogate species with C* = 103 and 105 μg m−3 are used for the IVOCs emitted by the above two source categories. Gas-phase photochemical reactions that change the volatility of the organics are taken into account. The oxidation products (SOA-sv, SOA-iv, and SOA-v of each group of precursors (SVOCs, IVOCs, and VOCs are simulated separately in the module to keep track of their origin. ORACLE efficiently describes the OA composition and evolution in the atmosphere and can be used to (i estimate the relative contributions of SOA and primary organic aerosol (POA to total OA, (ii determine how SOA concentrations are affected by biogenic and anthropogenic emissions, and (iii evaluate the effects of photochemical aging and long-range transport on the OA budget. Here we estimate that the predicted domain-average global surface OA concentration is 1.5 μg m−3 and consists of 7% POA from fuel combustion, 11% POA from biomass burning, 2% SOA-sv from fuel combustion, 3% SOA-sv from biomass burning, 15% SOA-iv from fuel combustion, 28% SOA-iv from biomass burning, 19% biogenic SOA-v, and 15% anthropogenic SOA-v. The tropospheric burden of OA components is predicted to be 0.23 Tg POA, 0.16 Tg SOA-sv, 1.41 Tg SOA-iv, and 1.2 Tg SOA-v.

  16. Changing Amazon biomass and the role of atmospheric CO2 concentration, climate, and land use

    Science.gov (United States)

    Almeida Castanho, Andrea D.; Galbraith, David; Zhang, Ke; Coe, Michael T.; Costa, Marcos H.; Moorcroft, Paul

    2016-01-01

    The Amazon tropical evergreen forest is an important component of the global carbon budget. Its forest floristic composition, structure, and function are sensitive to changes in climate, atmospheric composition, and land use. In this study biomass and productivity simulated by three dynamic global vegetation models (Integrated Biosphere Simulator, Ecosystem Demography Biosphere Model, and Joint UK Land Environment Simulator) for the period 1970-2008 are compared with observations from forest plots (Rede Amazónica de Inventarios Forestales). The spatial variability in biomass and productivity simulated by the DGVMs is low in comparison to the field observations in part because of poor representation of the heterogeneity of vegetation traits within the models. We find that over the last four decades the CO2 fertilization effect dominates a long-term increase in simulated biomass in undisturbed Amazonian forests, while land use change in the south and southeastern Amazonia dominates a reduction in Amazon aboveground biomass, of similar magnitude to the CO2 biomass gain. Climate extremes exert a strong effect on the observed biomass on short time scales, but the models are incapable of reproducing the observed impacts of extreme drought on forest biomass. We find that future improvements in the accuracy of DGVM predictions will require improved representation of four key elements: (1) spatially variable plant traits, (2) soil and nutrients mediated processes, (3) extreme event mortality, and (4) sensitivity to climatic variability. Finally, continued long-term observations and ecosystem-scale experiments (e.g. Free-Air CO2 Enrichment experiments) are essential for a better understanding of the changing dynamics of tropical forests.

  17. Changes in atmospheric CO2 levels recorded by the isotopic signature of n-alkanes from plants

    Science.gov (United States)

    Machado, Karina Scurupa; Froehner, Sandro

    2017-01-01

    The isotopic signature of sedimentary organic matter acts as a tracer for past changes in the terrestrial and aquatic carbon cycles. The temporal variation in δ13C values of n-alkanes from plants was assigned as resulting from changes in atmospheric composition in the study area, due to both global and local influences. Two rises in atmospheric CO2 concentration were assigned from the variation in n-alkane δ13C values for the periods between 1600 and 1880 and from 1930 to the present. In the first period, the sources of excess CO2 were predominantly natural, mainly volcanism, while in the second period local anthropogenic emissions were the major reason.

  18. Impacts of changes in land use and land cover on atmospheric chemistry and air quality over the 21st century

    Directory of Open Access Journals (Sweden)

    S. Wu

    2011-05-01

    Full Text Available The effects of future land use and land cover change on the chemical composition of the atmosphere and air quality are largely unknown. To investigate the potential effects associated with future changes in vegetation driven by atmospheric CO2 concentrations, climate, and anthropogenic land use over the 21st century, we performed a series of model experiments combining a general circulation model with a dynamic global vegetation model and an atmospheric chemical-transport model. Our results indicate that climate- and CO2-induced changes in vegetation composition and density could lead to decreases in summer afternoon surface ozone of up to 10 ppb over large areas of the northern mid-latitudes. This is largely driven by the substantial increases in ozone dry deposition associated with changes in the composition of temperate and boreal forests where conifer forests are replaced by those dominated by broadleaf tree types, as well as a CO2-driven increase in vegetation density. Climate-driven vegetation changes over the period 2000–2100 lead to general increases in isoprene emissions, globally by 15 % in 2050 and 36 % in 2100. These increases in isoprene emissions result in decreases in surface ozone concentrations where the NOx levels are low, such as in remote tropical rainforests. However, over polluted regions, such as the northeastern United States, ozone concentrations are calculated to increase with higher isoprene emissions in the future. Increases in biogenic emissions also lead to higher concentrations of secondary organic aerosols, which increase globally by 10 % in 2050 and 20 % in 2100. Surface concentrations of secondary organic aerosols are calculated to increase by up to 1 μg m−3 for large areas in Eurasia. When we use a scenario of future anthropogenic land use change, we find less increase in global isoprene emissions due to replacement of higher-emitting forests by lower

  19. Comparison of W–TiC composite coatings fabricated by atmospheric plasma spraying and supersonic atmospheric plasma spraying

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Qing Yu, E-mail: qingyuhou@hotmail.com [School of Material Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009 (China); Anhui Key Laboratory of Metal Materials and Processing, Maanshan, Anhui 243002 (China); Luo, Lai Ma [School of Material Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009 (China); Huang, Zhen Yi; Wang, Ping; Ding, Ting Ting [Anhui Key Laboratory of Metal Materials and Processing, Maanshan, Anhui 243002 (China); Wu, Yu Cheng, E-mail: ycwu@hfut.edu.cn [School of Material Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009 (China)

    2016-04-15

    Highlights: • W–TiC composite coatings were fabricated by APS and SAPS technologies. • TiC had filling effect on pores and coating/fixing effect on un-melted particles. • Porosity and oxygen content in SAPS coating were lower than that in APS coating. • Thermal conductivity of SAPS coating was higher than that of APS coating. • SAPS coating has better ability to resist to elastic fracture than APS coating does. - Abstract: Tungsten coatings with 1.5 wt.% TiC (W/TiC) were fabricated by atmospheric plasma spraying (APS) and supersonic atmospheric plasma spraying (SAPS) techniques, respectively. The results showed that the typical lamellar structure of plasma spraying and columnar crystalline grains formed in the coatings. Pores located mainly at lamellar gaps in association with oxidation were also observed. TiC phase, distributed at lamellar gaps filled the gaps; and that distributed around un-melted tungsten particles and splashed debris coated the particles or debris that were linked with the TiC at lamellar gaps. The coating and linking of the retained TiC phase prevented the tungsten particles to come off from the coatings. The porosity and the oxygen content of the SAPS-W/TiC were lower than those of the APS-W/TiC coating. The mechanical response of the coatings was strongly dependent on the H/E* ratio (H and E* are the hardness and effective Young’s modulus, respectively). The SAPS-W/TiC coating with a higher H/E* ratio had a better ability to resist to elastic fracture and better fracture toughness as compared with the APS-W/TiC coating with a smaller H/E* ratio. The thermal conductivity of the SAPS-W/TiC coating was greater than that of the APS-W/TiC coating.

  20. Cold-atmospheric pressure plasma polymerization of acetylene on wood flour for improved wood plastics composites

    Science.gov (United States)

    Lekobou, William; Pedrow, Patrick; Englund, Karl; Laborie, Marie-Pierre

    2009-10-01

    Plastic composites have become a large class of construction material for exterior applications. One of the main disadvantages of wood plastic composites resides in the weak adhesion between the polar and hydrophilic surface of wood and the non-polar and hydrophobic polyolefin matrix, hindering the dispersion of the flour in the polymer matrix. To improve interfacial compatibility wood flour can be pretreated with environmentally friendly methods such as cold-atmospheric pressure plasma. The objective of this work is therefore to evaluate the potential of plasma polymerization of acetylene on wood flour to improve the compatibility with polyolefins. This presentation will describe the reactor design used to modify wood flour using acetylene plasma polymerization. The optimum conditions for plasma polymerization on wood particles will also be presented. Finally preliminary results on the wood flour surface properties and use in wood plastic composites will be discussed.

  1. Emerging pattern of global change in the upper atmosphere and ionosphere

    Directory of Open Access Journals (Sweden)

    J. Laštovička

    2008-05-01

    Full Text Available In the upper atmosphere, greenhouse gases produce a cooling effect, instead of a warming effect. Increases in greenhouse gas concentrations are expected to induce substantial changes in the mesosphere, thermosphere, and ionosphere, including a thermal contraction of these layers. In this article we construct for the first time a pattern of the observed long-term global change in the upper atmosphere, based on trend studies of various parameters. The picture we obtain is qualitative, and contains several gaps and a few discrepancies, but the overall pattern of observed long-term changes throughout the upper atmosphere is consistent with model predictions of the effect of greenhouse gas increases. Together with the large body of lower atmospheric trend research, our synthesis indicates that anthropogenic emissions of greenhouse gases are affecting the atmosphere at nearly all altitudes between ground and space.

  2. Atmospheric pCO2 control on speleothem stable carbon isotope compositions

    Science.gov (United States)

    Breecker, Daniel O.

    2017-01-01

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

  3. A high-resolution mass spectrometer to measure atmospheric ion composition

    Directory of Open Access Journals (Sweden)

    H. Junninen

    2010-02-01

    Full Text Available In this paper we present recent achievements on developing and testing a tool to detect the composition of ambient ions in the mass/charge range up to 2000 Th. The instrument is an Atmospheric Pressure Interface Time-of-Flight Mass Spectrometer (APi-TOF, Tofwerk AG. Its mass accuracy is better than 0.002%, and the mass resolving power is 3000 Th/Th. In the data analysis, a new efficient Matlab based set of programs (tofTools were developed, tested and used. The APi-TOF was tested both in laboratory conditions and applied to outdoor air sampling in Helsinki at the SMEAR III station. Transmission efficiency calibrations showed a throughput of 0.1–0.5% in the range 100–1300 Th for positive ions, and linearity over 3 orders of magnitude in concentration was determined. In the laboratory tests the APi-TOF detected sulphuric acid-ammonia clusters in high concentration from a nebulised sample illustrating the potential of the instrument in revealing the role of sulphuric acid clusters in atmospheric new particle formation. The APi-TOF features a high enough accuracy, resolution and sensitivity for the determination of the composition of atmospheric small ions although the total concentration of those ions is typically only 400–2000 cm-3. The atmospheric ions were identified based on their exact masses, utilizing Kendrick analysis and correlograms as well as narrowing down the potential candidates based on their proton affinities as well isotopic patterns. In Helsinki during day-time the main negative ambient small ions were inorganic acids and their clusters. The positive ions were more complex, the main compounds were (polyalkyl pyridines and – amines. The APi-TOF provides a near universal interface for atmospheric pressure sampling, and this key feature will be utilized in future laboratory and field studies.

  4. Sensitivity of Oxygen Isotopes of Sulfate in Ice Cores to Past Changes in Atmospheric Oxidant Concentrations

    Science.gov (United States)

    Sofen, E. D.; Alexander, B.; Kunasek, S. A.; Mickley, L.; Murray, L. T.; Kaplan, J. O.

    2009-12-01

    The oxygen isotopic composition (Δ17O) of sulfate from ice cores allows for a quantitative assessment of the past oxidative capacity of the atmosphere, which has implications for the lifetime of pollutants (e.g. CO) and greenhouse gases (e.g. CH4), and changes in the sulfur budget on various timescales. Using Δ17O of sulfate measurements from the WAIS-Divide, Antarctica and Site-A, Greenland ice cores as constraints, we use the GEOS-Chem global three-dimensional chemical transport model to study changes in the concentrations of OH, O3, and H2O2 and their impact on sulfate Δ17O between the preindustrial and present-day. The Greenland ice core sulfate oxygen isotope observations are insensitive to changes in oxidant concentrations on the preindustrial-industrial timescale due to the rising importance of metal catalyzed S(IV) oxidation in mid- to high-northern latitudes resulting from anthropogenic metal emissions. The small change in Antarctic ice core sulfate Δ17O observations on this timescale is consistent with simultaneous increases in boundary layer O3 (32%) and H2O2 (49%) concentrations in the Southern Hemisphere, which have opposing effects on the sulfate O-isotope anomaly. Sulfate Δ17O is insensitive to the relatively small (-12%) decrease in Southern Hemisphere OH concentrations on this timescale due to the dominance of in-cloud versus gas-phase formation of sulfate in the mid-to-high southern latitudes. We find that the fraction of sulfate formed globally through gas-phase oxidation has not changed substantially between preindustrial and present times, however the total amount of sulfate formed in the gas-phase has nearly quadrupled due to rising anthropogenic emissions of sulfur dioxide. Measurements over a glacial-interglacial cycle from the Vostok core indicate dramatic changes in the Δ17O of sulfate on this timescale, which provide a strong constraint for glacial-era atmospheric chemistry modeling efforts. We will present preliminary results of

  5. Structural changes during pitch-based carbon granular composites carbonisation

    Energy Technology Data Exchange (ETDEWEB)

    Mendez, A.; Santamaria, R.; Granda, M.; Menendez, R. [CSIC, Oviedo (Spain)

    2008-02-15

    This article deals with the study of carbon composites behavior during their carbonization. Composites were prepared using four granular carbons (graphite, anthracite, green petroleum coke, and foundry coke) and four pitches (a commercial impregnating coal-tar pitch, an air-blown and two thermally treated pitches). The evolution of the optical microstructure, porosity, volume, and weight of carbon composites was monitored at different intermediate carbonization temperatures (350, 500, 700, and finally 1000{sup o}C). The porosity of composites increases with carbonization due to volume changes and weight loss of pitches. Weight loss of carbon composites during their carbonization mainly depends on the pitch characteristics and it was slightly influenced by the presence of granular carbon. On the other hand, carbon composites with the commercial coal-tar pitch and foundry coke, anthracite, or graphite deform in the initial stages of carbonization (<350{sup o}C) probably due to the lower porosity of the green pellets and the high amount of low-molecular weight compounds of the pitch. Carbon composites with green petroleum coke underwent important dimensional changes during their carbonization, expanding initially and then shrinking at temperatures above 700{sup o}C. The type of granular carbon strongly influenced the microstructure of the final carbon composite, as a result of its effect on the development of mesophase. Graphite, anthracite and foundry coke delays mesophase development, whereas green petroleum coke accelerates mesophase formation.

  6. A Decade of Field Changing Atmospheric Aerosol Research: Outcomes of EPA’s STAR Program

    Science.gov (United States)

    Conference: Gordon Research Conference in Atmospheric Chemistry, July 28 – August 2, 2013, VermontPresentation Type: PosterTitle: An Analysis of EPA’s STAR Program and a Decade of Field Changing Research in Atmospheric AerosolsAuthors: Kristina M. Wagstrom1,2, Sherri ...

  7. Simulated atmospheric N deposition alters fungal community composition and suppresses ligninolytic gene expression in a northern hardwood forest.

    Directory of Open Access Journals (Sweden)

    Ivan P Edwards

    Full Text Available High levels of atmospheric nitrogen (N deposition may result in greater terrestrial carbon (C storage. In a northern hardwood ecosystem, exposure to over a decade of simulated N deposition increased C storage in soil by slowing litter decay rates, rather than increasing detrital inputs. To understand the mechanisms underlying this response, we focused on the saprotrophic fungal community residing in the forest floor and employed molecular genetic approaches to determine if the slower decomposition rates resulted from down-regulation of the transcription of key lignocellulolytic genes, by a change in fungal community composition, or by a combination of the two mechanisms. Our results indicate that across four Acer-dominated forest stands spanning a 500-km transect, community-scale expression of the cellulolytic gene cbhI under elevated N deposition did not differ significantly from that under ambient levels of N deposition. In contrast, expression of the ligninolytic gene lcc was significantly down-regulated by a factor of 2-4 fold relative to its expression under ambient N deposition. Fungal community composition was examined at the most southerly of the four sites, in which consistently lower levels of cbhI and lcc gene expression were observed over a two-year period. We recovered 19 basidiomycete and 28 ascomycete rDNA 28S operational taxonomic units; Athelia, Sistotrema, Ceratobasidium and Ceratosebacina taxa dominated the basidiomycete assemblage, and Leotiomycetes dominated the ascomycetes. Simulated N deposition increased the proportion of basidiomycete sequences recovered from forest floor, whereas the proportion of ascomycetes in the community was significantly lower under elevated N deposition. Our results suggest that chronic atmospheric N deposition may lower decomposition rates through a combination of reduced expression of ligninolytic genes such as lcc, and compositional changes in the fungal community.

  8. Effect of Ingested Liquids on Color Change of Composite Resins

    Directory of Open Access Journals (Sweden)

    Beheshteh Malek Afzali

    2016-04-01

    Full Text Available Objectives: Color change of composite restorations is well known to dentists. However, the effect of commonly consumed drinks on discoloration of composite resins has yet to be determined. This study sought to assess the color change of a nanofilled (Premise and a flowable composite resin (Premise flowable following simulated consumption of tea, cola, iron drops and multivitamin syrup.Materials and Methods: Forty disk-shaped specimens (7 mm in diameter and 2 mm thick were fabricated from each composite resin. The baseline color values were measured according to the CIE L*a*b* system using digital imaging. The specimens of each restorative material were randomly divided into five groups (eight each according to the storage media namely tea, cola, iron drops, multivitamin syrup or distilled water (control. The specimens were immersed in staining solutions for three hours daily over a 40-day test period. Following this, the color change values (ΔE* were calculated. For statistical analyses, the color differences were analyzed using two-way ANOVA and Tukey’s test (P< 0.05.Results: There was no significant difference in ΔE* values between the two types of composite resins (P>0.05. In both composite materials, the difference among the solutions was not significant (P>0.05. Conclusion: Under the tested experimental conditions, both restorative materials were susceptible to discoloration by all four staining solutions. The color change values were not related to the solution or the type of material used.

  9. Changes in tropospheric composition and air quality due to stratospheric ozone depletion.

    Science.gov (United States)

    Solomon, Keith R; Tang, Xiaoyan; Wilson, Stephen R; Zanis, Prodromos; Bais, Alkiviadis F

    2003-01-01

    Increased UV-B through stratospheric ozone depletion leads to an increased chemical activity in the lower atmosphere (the troposphere). The effect of stratospheric ozone depletion on tropospheric ozone is small (though significant) compared to the ozone generated anthropogenically in areas already experiencing air pollution. Modeling and experimental studies suggest that the impacts of stratospheric ozone depletion on tropospheric ozone are different at different altitudes and for different chemical regimes. As a result the increase in ozone due to stratospheric ozone depletion may be greater in polluted regions. Attributable effects on concentrations are expected only in regions where local emissions make minor contributions. The vertical distribution of NOx (NO + NO2), the emission of volatile organic compounds and the abundance of water vapor, are important influencing factors. The long-term nature of stratospheric ozone depletion means that even a small increase in tropospheric ozone concentration can have a significant impact on human health and the environment. Trifluoroacetic acid (TFA) and chlorodifluoroacetic acid (CDFA) are produced by the atmospheric degradation of hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs). TFA has been measured in rain, rivers, lakes, and oceans, the ultimate sink for these and related compounds. Significant anthropogenic sources of TFA other than degradation HCFCs and HFCs have been identified. Toxicity tests under field conditions indicate that the concentrations of TFA and CDFA currently produced by the atmospheric degradation of HFCs and HCFCs do not present a risk to human health and the environment. The impact of the interaction between ozone depletion and future climate change is complex and a significant area of current research. For air quality and tropospheric composition, a range of physical parameters such as temperature, cloudiness and atmospheric transport will modify the impact of UV-B. Changes in the

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

    Science.gov (United States)

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

    2016-09-01

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

  11. Significant Atmospheric Boundary Layer Change Observed above an Agulhas Current Warm Cored Eddy

    Directory of Open Access Journals (Sweden)

    C. Messager

    2016-01-01

    Full Text Available The air-sea impact of a warm cored eddy ejected from the Agulhas Retroflection region south of Africa was assessed through both ocean and atmospheric profiling measurements during the austral summer. The presence of the eddy causes dramatic atmospheric boundary layer deepening, exceeding what was measured previously over such a feature in the region. This deepening seems mainly due to the turbulent heat flux anomaly above the warm eddy inducing extensive deep and persistent changes in the atmospheric boundary layer thermodynamics. The loss of heat by turbulent processes suggests that this kind of oceanic feature is an important and persistent source of heat for the atmosphere.

  12. New Views of Lunar Compositions and Rock Types Revealed by Spectroscopic Data from Chang'e-1 and Chang'e-3 Missions

    Science.gov (United States)

    Ling, Z. C.; Jolliff, B. L.

    2016-05-01

    Global hyperspectral imaging datasets of Chang'e-1 IIM have brought new science returns of lunar surface compositions and rock types. The in-situ spectroscopic measurements by Yutu yielded compositional constraints of a new type of basaltic rock.

  13. Impact of oceanic circulation changes on atmospheric δ13CO2

    Science.gov (United States)

    Menviel, L.; Mouchet, A.; Meissner, K. J.; Joos, F.; England, M. H.

    2015-12-01

    δ13CO2 measured in Antarctic ice cores provides constraints on oceanic and terrestrial carbon cycle processes linked with millennial-scale and glacial/interglacial changes in atmospheric CO2. However, the interpretation of δ13CO2 is not straightforward. Using two Earth system models of intermediate complexity we perform a set of sensitivity experiments in which the formation rates of North Atlantic Deep Water (NADW), North Pacific Deep Water (NPDW), Antarctic Bottom Water (AABW) and Antarctic Intermediate Water (AAIW) are varied. We study the impact of these circulation changes on atmospheric δ13CO2 as well as on the oceanic δ13C distribution. In general, we find that the formation rates of AABW, NADW, NPDW and AAIW are negatively correlated with changes in δ13CO2: namely strong oceanic ventilation decreases atmospheric δ13CO2. However, since large scale ocean circulation reorganizations also impact nutrient utilization and the Earth's climate the relationship between atmospheric δ13CO2 levels and ocean ventilation rate is not unequivocal. In both models atmospheric δ13CO2 is very sensitive to changes in AABW formation rates: increased AABW formation enhances the upwelling of low δ13C waters to the surface and decreases atmospheric δ13CO2. By contrast, the impact of NADW changes on atmospheric δ13CO2 is less robust and might be model dependent.

  14. Thermal Stress Effect on Density Changes of Hemp Hurds Composites

    Science.gov (United States)

    Schwarzova, Ivana; Cigasova, Julia; Stevulova, Nadezda

    2016-12-01

    The aim of this article is to study the behavior of prepared biocomposites based on hemp hurds as a filling agent in composite system. In addition to the filler and water, an alternative binder, called MgO-cement was used. For this objective were prepared three types of samples; samples based on untreated hemp hurds as a referential material and samples based on chemically (with NaOH solution) and physically (by ultrasonic procedure) treated hemp hurds. The thermal stress effect on bulk density changes of hemp hurds composites was monitored. Gradual increase in temperature led to composites density reduction of 30-40 %. This process is connected with mass loss of the adsorbed moisture and physically bound water and also with degradation of organic compounds present in hemp hurds aggregates such as pectin, hemicelluloses and cellulose. Therefore the changes in the chemical composition of treated hemp hurds in comparison to original sample and its thermal decomposition were also studied.

  15. Keratinocytes at the uppermost layer of epidermis might act as sensors of atmospheric pressure change.

    Science.gov (United States)

    Denda, Mitsuhiro

    2016-01-01

    It has long been suggested that climate, especially atmospheric pressure change, can cause health problems ranging from migraine to myocardial infarction. Here, I hypothesize that the sensory system of epidermal keratinocytes mediates the influence of atmospheric pressure change on the human physiological condition. We previously demonstrated that even subtle changes of atmospheric pressure (5-20 hPa) induce elevation of intracellular calcium level in cultured human keratinocytes (excitation of keratinocytes). It is also established that communication occurs between epidermal keratinocytes and peripheral nerve systems. Moreover, various neurotransmitters and hormones that influence multiple systems (nervous, cardiovascular, endocrine, and immune systems) are generated and released from epidermal keratinocytes in response to various external stimuli. Thus, I suggest that pathophysiological phenomena induced by atmospheric pressure changes might be triggered by epidermal keratinocytes.

  16. Chemical composition of atmospheric precipitation on the south of Ukraine (Crimea)

    Science.gov (United States)

    Klymenko, O.; Klymenko, M.

    The data of long monitoring of volume and chemical content of atmospheric precipitation in steppe Crimea near to the large plantations of fruit orchards are given The purpose of researches was detection of acid deposits establishment of connection them dI with chemical structure for the operative tracking behind a condition of air It was established that the sum of precipitations for year was increased basically at the summer deposits The annual volume-weighted logarithmic range of dI values were 4 83-5 73 in precipitation There were more less values in a cold season than in warm one The absolute minimum was equal 3 82 For the researched period mean dI values of atmospheric precipitation in a cold season gradually raised and in warm - was reduced and has reached the minimum in 2000-2001 years It resulted in damages of fruit plants during long term rains in vegetation period The dominant anion in atmospheric precipitation was SO 4 2- which content basically determined of them acidification The important role in this process also belongs to ions NO 3 - and Cl - Mean seasons concentrations of these ions tend to increase It probably may be connected both to distant distribution of emission and with local anthropogenic activity In connection with an establishment of atmospheric precipitation acidification and also incidental and casual phenomenon there is a necessity of their composition monitoring for agricultural areas near to the large fruit plantations for big number years during whole year

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

    Science.gov (United States)

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

    2017-01-01

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

  18. CLIMATE CHANGE. Long-term climate forcing by atmospheric oxygen concentrations.

    Science.gov (United States)

    Poulsen, Christopher J; Tabor, Clay; White, Joseph D

    2015-06-12

    The percentage of oxygen in Earth's atmosphere varied between 10% and 35% throughout the Phanerozoic. These changes have been linked to the evolution, radiation, and size of animals but have not been considered to affect climate. We conducted simulations showing that modulation of the partial pressure of oxygen (pO2), as a result of its contribution to atmospheric mass and density, influences the optical depth of the atmosphere. Under low pO2 and a reduced-density atmosphere, shortwave scattering by air molecules and clouds is less frequent, leading to a substantial increase in surface shortwave forcing. Through feedbacks involving latent heat fluxes to the atmosphere and marine stratus clouds, surface shortwave forcing drives increases in atmospheric water vapor and global precipitation, enhances greenhouse forcing, and raises global surface temperature. Our results implicate pO2 as an important factor in climate forcing throughout geologic time.

  19. Plasma penetration depth and mechanical properties of atmospheric plasma-treated 3D aramid woven composites

    Energy Technology Data Exchange (ETDEWEB)

    Chen, X.; Yao, L.; Xue, J.; Zhao, D.; Lan, Y.; Qian, X. [Key Laboratory of Textile Science and Technology, Donghua University, Ministry of Education (China); Department of Textile Materials Science and Product Design, College of Textiles, Donghua University, Shanghai 201620 (China); Wang, C.X. [Key Laboratory of Textile Science and Technology, Donghua University, Ministry of Education (China); Department of Textile Materials Science and Product Design, College of Textiles, Donghua University, Shanghai 201620 (China); College of Textiles and Clothing, Yancheng Institute of Technology, Jiangsu 224003 (China); Qiu, Y. [Key Laboratory of Textile Science and Technology, Donghua University, Ministry of Education (China); Department of Textile Materials Science and Product Design, College of Textiles, Donghua University, Shanghai 201620 (China)], E-mail: ypqiu@dhu.edu.cn

    2008-12-30

    Three-dimensional aramid woven fabrics were treated with atmospheric pressure plasmas, on one side or both sides to determine the plasma penetration depth in the 3D fabrics and the influences on final composite mechanical properties. The properties of the fibers from different layers of the single side treated fabrics, including surface morphology, chemical composition, wettability and adhesion properties were investigated using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), contact angle measurement and microbond tests. Meanwhile, flexural properties of the composites reinforced with the fabrics untreated and treated on both sides were compared using three-point bending tests. The results showed that the fibers from the outer most surface layer of the fabric had a significant improvement in their surface roughness, chemical bonding, wettability and adhesion properties after plasma treatment; the treatment effect gradually diminished for the fibers in the inner layers. In the third layer, the fiber properties remained approximately the same to those of the control. In addition, three-point bending tests indicated that the 3D aramid composite had an increase of 11% in flexural strength and 12% in flexural modulus after the plasma treatment. These results indicate that composite mechanical properties can be improved by the direct fabric treatment instead of fiber treatment with plasmas if the fabric is less than four layers thick.

  20. Deforestation changes land-atmosphere interactions across South American biomes

    Science.gov (United States)

    Salazar, Alvaro; Katzfey, Jack; Thatcher, Marcus; Syktus, Jozef; Wong, Kenneth; McAlpine, Clive

    2016-04-01

    South American biomes are increasingly affected by land use/land cover change. However, the climatic impacts of this phenomenon are still not well understood. In this paper, we model vegetation-climate interactions with a focus on four main biomes distributed in four key regions: The Atlantic Forest, the Cerrado, the Dry Chaco, and the Chilean Matorral ecosystems. We applied a three member ensemble climate model simulation for the period 1981-2010 (30 years) at 25 km resolution over the focus regions to quantify the changes in the regional climate resulting from historical deforestation. The results of computed modelling experiments show significant changes in surface fluxes, temperature and moisture in all regions. For instance, simulated temperature changes were stronger in the Cerrado and the Chilean Matorral with an increase of between 0.7 and 1.4 °C. Changes in the hydrological cycle revealed high regional variability. The results showed consistent significant decreases in relative humidity and soil moisture, and increases in potential evapotranspiration across biomes, yet without conclusive changes in precipitation. These impacts were more significant during the dry season, which resulted to be drier and warmer after deforestation.

  1. Effects of atmospheric and climate change at the timberline of the Central European Alps

    OpenAIRE

    2009-01-01

    This review considers potential effects of atmospheric change and climate warming within the timberline ecotone of the Central European Alps. After focusing on the impacts of ozone (O3) and rising atmospheric CO2 concentration, effects of climate warming on the carbon and water balance of timberline trees and forests will be outlined towards conclusions about changes in tree growth and treeline dynamics.Presently, ambient ground-level O3 concentrations do not exert crucial stress on adult con...

  2. Changes in thickness of magnetized composites due to current flow

    Science.gov (United States)

    Bednarek, S.

    1998-02-01

    The pinch magnitude in monolithic metal conductors and ferromagnetics was estimated in this paper. The conditions for the material were formulated so that the pinch which occurs in it could reach the magnitude useful for applications. The way of production of a special composite with a laminar structure was described. The composite consists of sheets of copper foil separating the layers of the elastic ferromagnet which was made by the dispersion of hard magnetic particles in silicon. Using a measuring system containing a Michelson interferometer, measurements of changes were made in the thickness of the produced composite samples during the electric current flow. The obtained results were discussed.

  3. Changes in coccolith calcification under stable atmospheric CO2

    Directory of Open Access Journals (Sweden)

    C. Bauke

    2013-06-01

    Full Text Available Coccolith calcification is known to respond to ocean acidification in culture experiments as well as in present and past oceans. Previous studies basically focus on changes in coccolith weight due to increasing CO2 and the resulting changes in the carbonate system but pay little attention to the influence of other environmental factors. In order to untangle changes in coccolithophore calcification due to environmental factors such as temperature and/or productivity from changes caused by increasing pCO2 and carbonate ion concentration we here present a study on coccolith calcification from the Holocene North Atlantic Ocean. The pre-industrial Holocene with its predominantly stable carbonate system provides the conditions for such a comprehensive analysis. For a realistic analysis on changes in major components of Holocene coccolithophores, the family Noelaerhabdaceae was selected, which constitutes the main part of the assemblage in the North Atlantic. Records of average coccolith weights from three Holocene sediment cores along a North–South transect in the North Atlantic were analysed. During the Holocene mean weight (and therefore calcification of Noelaerhabdaceae (E. huxleyi and Gephyrocapsa coccoliths decreases at the Azores (Geofar KF 16 from around 7 to 5.5 pg, but increases at the Rockall Plateau (ODP Site 980 from around 6 to 8 pg and at the Vøring Plateau (MD08-3192 from 7 to 10.5 pg. This amplitude of average weight variability is within the range of glacial/interglacial changes that were interpreted to be an effect of decreasing carbonate ion concentration. By comparison with SEM assemblage counts, we show that weight changes are partly due to variations in the coccolithophore assemblage, but also an effect of a change in calcification and/or morphotype variability within single species. Our results indicate that there is no single key factor responsible for the observed changes in coccolith weight. A major increase in coccolith

  4. Changes in coccolith calcification under stable atmospheric CO2

    Science.gov (United States)

    Bauke, C.; Meier, K. J. S.; Kinkel, H.; Baumann, K.-H.

    2013-06-01

    Coccolith calcification is known to respond to ocean acidification in culture experiments as well as in present and past oceans. Previous studies basically focus on changes in coccolith weight due to increasing CO2 and the resulting changes in the carbonate system but pay little attention to the influence of other environmental factors. In order to untangle changes in coccolithophore calcification due to environmental factors such as temperature and/or productivity from changes caused by increasing pCO2 and carbonate ion concentration we here present a study on coccolith calcification from the Holocene North Atlantic Ocean. The pre-industrial Holocene with its predominantly stable carbonate system provides the conditions for such a comprehensive analysis. For a realistic analysis on changes in major components of Holocene coccolithophores, the family Noelaerhabdaceae was selected, which constitutes the main part of the assemblage in the North Atlantic. Records of average coccolith weights from three Holocene sediment cores along a North-South transect in the North Atlantic were analysed. During the Holocene mean weight (and therefore calcification) of Noelaerhabdaceae (E. huxleyi and Gephyrocapsa) coccoliths decreases at the Azores (Geofar KF 16) from around 7 to 5.5 pg, but increases at the Rockall Plateau (ODP Site 980) from around 6 to 8 pg and at the Vøring Plateau (MD08-3192) from 7 to 10.5 pg. This amplitude of average weight variability is within the range of glacial/interglacial changes that were interpreted to be an effect of decreasing carbonate ion concentration. By comparison with SEM assemblage counts, we show that weight changes are partly due to variations in the coccolithophore assemblage, but also an effect of a change in calcification and/or morphotype variability within single species. Our results indicate that there is no single key factor responsible for the observed changes in coccolith weight. A major increase in coccolith weight occurs

  5. Tight coupling of particle size, number and composition in atmospheric cloud droplet activation

    Directory of Open Access Journals (Sweden)

    D. O. Topping

    2012-04-01

    Full Text Available The substantial uncertainty in the indirect effect of aerosol particles on radiative forcing in large part arises from the influences of atmospheric aerosol particles on (i the brightness of clouds, exerting significant shortwave cooling with no appreciable compensation in the long wave, and on (ii their ability to precipitate, with implications for cloud cover and lifetime.

    Predicting the ambient conditions at which aerosol particles may become cloud droplets is largely reliant on an equilibrium relationship derived by Köhler (1936. However, the theoretical basis of the relationship restricts its application to particles solely comprising involatile compounds and water, whereas a substantial fraction of particles in the real atmosphere will contain potentially thousands of semi-volatile organic compounds in addition to containing semi-volatile inorganic components such as ammonium nitrate.

    We show that equilibration of atmospherically reasonable concentrations of organic compounds with a growing particle as the ambient humidity increases has potentially larger implications on cloud droplet formation than any other equilibrium compositional dependence, owing to inextricable linkage between the aerosol composition, a particles size and concentration under ambient conditions.

    Whilst previous attempts to account for co-condensation of gases other than water vapour have been restricted to one inorganic condensate, our method demonstrates that accounting for the co-condensation of any number of organic compounds substantially decreases the saturation ratio of water vapour required for droplet activation. This effect is far greater than any other compositional dependence; more so even than the unphysical effect of surface tension reduction in aqueous organic mixtures, ignoring differences in bulk and surface surfactant concentrations.

  6. Using Enthalpy as a Prognostic Variable in Atmospheric Modelling with Variable Composition

    Science.gov (United States)

    2016-04-14

    tories, and the equation of state p = ∑ i pi = ∑ i ρiRiT = ρRT . (4) Here Ri = kB/mi are individual gas constants for each species and kB is the...relation between the mass, pressure, and temperature fields via the equation of state (4). The use of virtual temperature in Equation (11) implies that...internal energy equation as a convenient prognostic thermodynamic variable for atmospheric modelling with variable composition, including models of

  7. Water security, global change and land-atmosphere feedbacks.

    Science.gov (United States)

    Dadson, Simon; Acreman, Michael; Harding, Richard

    2013-11-13

    Understanding the competing pressures on water resources requires a detailed knowledge of the future water balance under uncertain environmental change. The need for a robust, scientifically rigorous evidence base for effective policy planning and practice has never been greater. Environmental change includes, but is not limited to, climate change; it also includes land-use and land-cover change, including deforestation for agriculture, and occurs alongside changes in anthropogenic interventions that are used in natural resource management such as the regulation of river flows using dams, which can have impacts that frequently exceed those arising in the natural system. In this paper, we examine the role that land surface models can play in providing a robust scientific basis for making resource management decisions against a background of environmental change. We provide some perspectives on recent developments in modelling in land surface hydrology. Among the range of current land surface and hydrology models, there is a large range of variability, which indicates that the specification and parametrization of several basic processes in the models can be improved. Key areas that require improvement in order to address hydrological applications include (i) the representation of groundwater in models, particularly at the scales relevant to land surface modelling, (ii) the representation of human interventions such as dams and irrigation in the hydrological system, (iii) the quantification and communication of uncertainty, and (iv) improved understanding of the impact on water resources availability of multiple use through treatment, recycling and return flows (and the balance of consumptive and conservative uses). Through a series of examples, we demonstrate that changes in water use could have important reciprocal impacts on climate over a wide area. The effects of water management decisions on climate feedbacks are only beginning to be investigated-they are

  8. Changes to the chemical composition of soot from heterogeneous oxidation reactions.

    Science.gov (United States)

    Browne, Eleanor C; Franklin, Jonathan P; Canagaratna, Manjula R; Massoli, Paola; Kirchstetter, Thomas W; Worsnop, Douglas R; Wilson, Kevin R; Kroll, Jesse H

    2015-02-19

    The atmospheric aging of soot particles, in which various atmospheric processes alter the particles' chemical and physical properties, is poorly understood and consequently is not well-represented in models. In this work, soot aging via heterogeneous oxidation by OH and ozone is investigated using an aerosol flow reactor coupled to a new high-resolution aerosol mass spectrometric technique that utilizes infrared vaporization and single-photon vacuum ultraviolet ionization. This analytical technique simultaneously measures the elemental and organic carbon components of soot, allowing for the composition of both fractions to be monitored. At oxidant exposures relevant to the particles' atmospheric lifetimes (the equivalent of several days of oxidation), the elemental carbon portion of the soot, which makes up the majority of the particle mass, undergoes no discernible changes in mass or composition. In contrast, the organic carbon (which in the case of methane flame soot is dominated by aliphatic species) is highly reactive, undergoing first the addition of oxygen-containing functional groups and ultimately the loss of organic carbon mass from fragmentation reactions that form volatile products. These changes occur on time scales comparable to those of other nonoxidative aging processes such as condensation, suggesting that further research into the combined effects of heterogeneous and condensational aging is needed to improve our ability to accurately predict the climate and health impacts of soot particles.

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

    Science.gov (United States)

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

    1991-01-01

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

  10. Changes in the Earth's Spin Rotation due to the Atmospheric Effects and Reduction in Glaciers

    Science.gov (United States)

    Na, Sung-Ho; Cho, Jungho; Kim, Tu-Hwan; Seo, Kiweon; Youm, Kookhyoun; Yoo, Sung-Moon; Choi, Byungkyu; Yoon, Hasu

    2016-12-01

    The atmosphere strongly affects the Earth's spin rotation in wide range of timescale from daily to annual. Its dominant role in the seasonal perturbations of both the pole position and spinning rate of the Earth is once again confirmed by a comparison of two recent data sets; i) the Earth orientation parameter and ii) the global atmospheric state. The atmospheric semi-diurnal tide has been known to be a source of the Earth's spin acceleration, and its magnitude is re-estimated by using an enhanced formulation and an up-dated empirical atmospheric S2 tide model. During the last twenty years, an unusual eastward drift of the Earth's pole has been observed. The change in the Earth's inertia tensor due to glacier mass redistribution is directly assessed, and the recent eastward movement of the pole is ascribed to this change. Furthermore, the associated changes in the length of day and UT1 are estimated.

  11. Modeled subalpine plant community response to climate change and atmospheric nitrogen deposition in Rocky Mountain National Park, USA.

    Science.gov (United States)

    McDonnell, T C; Belyazid, S; Sullivan, T J; Sverdrup, H; Bowman, W D; Porter, E M

    2014-04-01

    To evaluate potential long-term effects of climate change and atmospheric nitrogen (N) deposition on subalpine ecosystems, the coupled biogeochemical and vegetation community competition model ForSAFE-Veg was applied to a site at the Loch Vale watershed of Rocky Mountain National Park, Colorado. Changes in climate and N deposition since 1900 resulted in pronounced changes in simulated plant species cover as compared with ambient and estimated future community composition. The estimated critical load (CL) of N deposition to protect against an average future (2010-2100) change in biodiversity of 10% was between 1.9 and 3.5 kg N ha(-1) yr(-1). Results suggest that the CL has been exceeded and vegetation at the study site has already undergone a change of more than 10% as a result of N deposition. Future increases in air temperature are forecast to cause further changes in plant community composition, exacerbating changes in response to N deposition alone.

  12. Mars Atmospheric Composition, Isotope Ratios and Seasonal Variations: Overview and Updates of the SAM Measurements at Gale Crater

    Science.gov (United States)

    Webster, C. R.; Mahaffy, P. R.; Atreya, S. K.; Conrad, P. G.; Franz, H.; Trainer, M. G.; Wong, M. H.; Mischna, M. A.; Flesch, G.; Farley, K. A.; Owen, T. C.; Niles, P. B.; Jones, J. H.; Christensen, L. E.; Martín-Torres, J.; Zorzano, M. P.

    2014-12-01

    We will summarize the in situ measurements of atmospheric composition and the isotopic ratios of D/H in water, 13C/12C, 18O/16O, 17O/16O, and 13C18O/12C16O in carbon dioxide, 38Ar/36Ar, xKr/84Kr, and 15N/14N made in the martian atmosphere at Gale Crater from the Curiosity Rover using the Sample Analysis at Mars (SAM)'s Quadrupole Mass Spectrometer (QMS) and Tunable Laser Spectrometer (TLS). With data over 700 sols since the Curiosity landing, we will discuss evidence and implications for changes on seasonal and other timescales. We will also present results for continued methane and methane enrichment experiments over this time period. Comparison between our measurements in the modern atmosphere and those of martian meteorites like ALH 84001 implies that the martian reservoirs of CO2 and H2O were largely established ~4 billion years ago, but that atmospheric loss or surface interaction may be still ongoing. References:[1] Mahaffy P. R. et al., Science, 341, 263-266, 2013, doi:10.1126/science.1237966. [2] Webster C. R. et al. (2013), Science, 341, 260-263, doi:10.1126/science.1237961. [3] Wong, M. H. et al. (2013), Geophys. Res. Lett., doi:10.1002/2013GL057840. [4] Atreya S. K. et al (2013), Geophys. Res. Lett., 40, 1-5, doi:10.1002/2013GL057763. The research described here was supported by the National Aeronautics and Space Administration (NASA).

  13. Ten years of elemental atmospheric metal fallout and Pb isotopic composition monitoring using lichens in north-eastern France

    Science.gov (United States)

    Cloquet, Christophe; Estrade, Nicolas

    2016-04-01

    We report on the chemical and Pb isotopic compositions of epiphytic lichens collected from small tree branches in the urban area of the city of Metz (NE France). Lichens were collected in five different years between 2001 and 2009. The data are first compared year to year in order to document any temporal changes and trends in metal atmospheric fallout. The area studied was then subdivided into different zones on the basis of land-use (urban, suburban, rural and industrial) in order to determine potential spatial gradients. The median concentrations and enrichment factors (EF, normalized to Al) of Pb and other metals (Cu, Zn, Cd, Ni, Cr, Hg, Fe) in lichens from the urban, suburban, and rural zones show no systematic variation between 2001 and 2008. However, the metal EFs show spatial variation and are generally highest in the urban area and lowest in the rural area. Lichens within the industrial zone (collected in 2009), which is dominated by steel industries, are richest in Al, Fe, Cr, Pb, and Zn. Although the Al concentration is high in these lichens, the EFs for the cited metals are several times higher than those measured in lichens from the other three zones. No significant differences were noted for Hg, Cd, Cu and or Ni. Lead isotopic compositions measured in lichens may be highly variable from year to year and from zone to zone. The variation is primarily interpreted to result from mixing between: (i) Pb added to gasoline (and recycled through re-emission of road dust in the atmosphere); (ii) regional industrial Pb from long-range transportation and/or mixed with urban Pb; and (iii) local industrial Pb. The median isotopic compositions of individual zones are distinct, suggesting variable mixing of these three sources. The annual variations show that 2001 was most affected by gasoline Pb, whereas 2003 and 2006 were more affected by the local steel industry.

  14. Ten years of elemental atmospheric metal fallout and Pb isotopic composition monitoring using lichens in northeastern France

    Science.gov (United States)

    Cloquet, Christophe; Estrade, Nicolas; Carignan, Jean

    2015-09-01

    We report on the chemical and Pb isotopic compositions of epiphytic lichens collected from small tree branches in the urban area of the city of Metz (NE France). Lichens were collected in five different years between 2001 and 2009. The data are first compared year to year in order to document any temporal change and trend in metal atmospheric fallout. The area studied was then subdivided into different zones on the basis of land use (urban, suburban, rural and industrial) in order to determine potential spatial gradients. The median concentrations and enrichment factors (EF, normalized to Al) of Pb and other metals (Cu, Zn, Cd, Ni, Cr, Hg, Fe) in lichens from the urban, suburban, and rural zones show no systematic variation between 2001 and 2008. However, the metal EFs show spatial variation and are generally highest in the urban area and lowest in the rural area. Lichens within the industrial zone (collected in 2009), which is dominated by steel industries, are richest in Al, Fe, Cr, Pb, and Zn. Although the Al concentration is high in these lichens, the EFs for the cited metals are several times higher than those measured in lichens from the other three zones. No significant differences were noted for Hg, Cd, Cu and or Ni. Pb isotopic compositions measured in lichens may be highly variable from year to year and from zone to zone. The variation is primarily interpreted to result from mixing between: (i) Pb added to gasoline (and recycled through re-emission of road dust in the atmosphere); (ii) regional industrial Pb from long-range transportation and/or mixed with urban Pb; and (iii) local industrial Pb. The median isotopic compositions of individual zones are distinct, suggesting variable mixing of these three sources. The annual variations show that 2001 was most affected by gasoline Pb, whereas 2003 and 2006 were more affected by the local steel industry.

  15. Glacial-Interglacial Atmospheric CO2 Change--The Glacial Burial Hypothesis

    Institute of Scientific and Technical Information of China (English)

    Ning ZENG

    2003-01-01

    Organic carbon buried under the great ice sheets of the Northern Hemisphere is suggested to bethe missing link in the atmospheric CO2 change over the glacial-interglacial cycles. At glaciation, theadvancement of continental ice sheets buries vegetation and soil carbon accumulated during warmer pe-riods. At deglaciation, this burial carbon is released back into the atmosphere. In a simulation over twoglacial-interglacial cycles using a synchronously coupled atmosphere-land-ocean carbon model forced byreconstructed climate change, it is found that there is a 547-Gt terrestrial carbon release from glacialmaximum to interglacial, resulting in a 60-Gt (about 30-ppmv) increase in the atmospheric CO2, with theremainder absorbed by the ocean in a scenario in which ocean acts as a passive buffer. This is in contrastto previous estimates of a land uptake at deglaciation. This carbon source originates from glacial burial,continental shelf, and other land areas in response to changes in ice cover, sea level, and climate. The inputof light isotope enriched terrestrial carbon causes atmospheric 513C to drop by about 0.3% at deglaciation,followed by a rapid rise towards a high interglacial value in response to oceanic warming and regrowthon land. Together with other ocean based mechanisms such as change in ocean temperature, the glacialburial hypothesis may offer a full explanation of the observed 80 100-ppmv atmospheric CO2 change.

  16. Mycorrhizal mediation of plant response to atmospheric change: Air quality concepts and research considerations.

    Science.gov (United States)

    Shafer, S R; Schoeneberger, M M

    1991-01-01

    The term 'global climate change' encompasses many physical and chemical changes in the atmosphere that have been induced by anthropogenic pollutants. Increases in concentrations of CO2 and CH4 enhance the 'greenhouse effect' of the atmosphere and may contribute to changes in temperature and precipitation patterns at the earth's surface. Nitrogen oxides and SO2 are phytotoxic and also react with other pollutants to produce other phytotoxins in the troposphere such as O3 and acidic substances. However, release of chlorofluorocarbons into the atmosphere may cause depletion of stratospheric O3, increasing the transmittance of ultraviolet-B (UV-B) radiation to the earth's surface. Increased intensities of UV-B could affect plants and enhance photochemical reactions that generate some phytotoxic pollutants. The role of mycorrhizae in plant responses to such stresses has received little attention. Although plans for several research programs have acknowledged the importance of drought tolerance and soil fertility in plant responses to atmospheric stresses, mycorrhizae are rarely targeted to receive specific investigation. Most vascular land plants form mycorrhizae, so the role of mycorrhizae in mediating plant responses to atmospheric change may be an important consideration in predicting effects of atmospheric changes on plants in managed and natural ecosystems.

  17. Comparison of ZrB2-MoSi2 Composite Coatings Fabricated by Atmospheric and Vacuum Plasma Spray Processes

    Science.gov (United States)

    Niu, Yaran; Wang, Zhong; Zhao, Jun; Zheng, Xuebin; Zeng, Yi; Ding, Chuanxian

    2016-12-01

    In this work, ZrB2-20 vol.% MoSi2 (denoted as ZM) composite coatings were fabricated by atmospheric plasma spray (APS) and vacuum plasma spray (VPS) techniques, respectively. Phase composition and microstructure of the composite coatings were characterized. Their oxidation behaviors and microstructure changes at 1500 °C were comparatively investigated. The results showed that VPS-ZM coating was composed of hexagonal ZrB2, tetragonal and hexagonal MoSi2, while certain amount of ZrO2 existed in APS-ZM coating. The oxide content, surface roughness and porosity of VPS-ZM coating were apparently lower than those of APS-ZM coating. The mass gain of APS-ZM coating was maximum at the beginning (1500 °C, 0 h) and then decreased with the oxidation time extending, while the mass of VPS-ZM coating gradually increased with increasing the oxidation time. The possible reasons for the different oxidation behaviors of the two kinds of coatings were analyzed.

  18. Effects of resolution on the relative importance of numerical and physical horizontal diffusion in atmospheric composition modelling

    Directory of Open Access Journals (Sweden)

    M. D'Isidoro

    2010-03-01

    Full Text Available Numerical diffusion induced by advection has a large influence on concentration of substances in atmospheric composition models. At coarse resolution numerical effects dominate, whereas at increasing model resolution a description of physical diffusion is needed. A method to investigate the effects of changing resolution and Courant number is defined here and is applied to the WAF advection scheme (used in BOLCHEM, evidencing a sub-diffusive process. The spread rate from an instantaneous source caused by numerical diffusion is compared to that produced by the physical diffusion necessary to simulate unresolved turbulent motions. The time at which the physical diffusion process overpowers the numerical spread is estimated, and it is shown to reduce as the resolution increases, and to increase with wind velocity.

  19. Impact of sea ice cover changes on the Northern Hemisphere atmospheric winter circulation

    Directory of Open Access Journals (Sweden)

    D. Handorf

    2012-01-01

    Full Text Available The response of the Arctic atmosphere to low and high sea ice concentration phases based on European Center for Medium-Range Weather Forecast (ECMWF Re-Analysis Interim (ERA-Interim atmospheric data and Hadley Centre's sea ice dataset (HadISST1 from 1989 until 2010 has been studied. Time slices of winter atmospheric circulation with high (1990–2000 and low (2001–2010 sea ice concentration in the preceding August/September have been analysed with respect to tropospheric interactions between planetary and baroclinic waves. It is shown that a changed sea ice concentration over the Arctic Ocean impacts differently the development of synoptic and planetary atmospheric circulation systems. During the low ice phase, stronger heat release to the atmosphere over the Arctic Ocean reduces the atmospheric vertical static stability. This leads to an earlier onset of baroclinic instability that further modulates the non-linear interactions between baroclinic wave energy fluxes on time scales of 2.5–6 d and planetary scales of 10–90 d. Our analysis suggests that Arctic sea ice concentration changes exert a remote impact on the large-scale atmospheric circulation during winter, exhibiting a barotropic structure with similar patterns of pressure anomalies at the surface and in the mid-troposphere. These are connected to pronounced planetary wave train changes notably over the North Pacific.

  20. An approximate atmospheric guidance law for aeroassisted plane change maneuvers

    Science.gov (United States)

    Speyer, Jason L.; Crues, Edwin Z.

    1988-01-01

    An approximate optimal guidance law for the aeroassisted plane change problem is presented which is based upon an expansion of the Hamilton-Jacobi-Bellman equation with respect to the small parameter of Breakwell et al. (1985). The present law maximizes the final velocity of the reentry vehicle while meeting terminal constraints on altitude, flight path angle, and heading angle. The integrable zeroth-order solution found when the small parameter is set to zero corresponds to a solution of the problem where the aerodynamic forces dominate the inertial forces. Higher order solutions in the expansion are obtained from the solution of linear partial differential equations requiring only quadrature integration.

  1. Flavor changing neutral currents in a realistic composite technicolor model

    Science.gov (United States)

    Carone, Christopher D.; Hamilton, Rowan T.

    1993-03-01

    We consider the phenomenology of a composite technicolor model proposed recently by Georgi. Composite technicolor interactions produce four-quark operators in the low energy theory that contribute to flavor changing neutral current processes. While we expect operators of this type to be induced at the compositeness scale by the flavor-symmetry breaking effects of the preon mass matrices, the Georgi model also includes operators from higher scales that are not GIM-suppressed. Since these operators are potentially large, we study their impact on flavor changing neutral currents and CP violation in the neutral K, B, and D meson systems. Notably, we find that this model gives rise to a typical value for {ɛ‧}/{ɛ} that is much smaller than most standard model estimates.

  2. Changes in atmospheric nitrate deposition in Germany--an isotopic perspective.

    Science.gov (United States)

    Beyn, Fabian; Matthias, Volker; Dähnke, Kirstin

    2014-11-01

    We investigated the isotopic composition of atmospheric NO3(-) deposition at a moderately polluted site in Western Europe over an annual cycle from December 2011 to November 2012. On average, we measured load-weighted δ(15)N values of +0.1 and +3.0‰ in wet and dry deposition, respectively. A comparison to source-specific N emission trends and to isotope data from the 1980s reveals distinct changes in δ(15)N-NO3(-) values: In contrast to the increasing relative importance of isotopically depleted natural NOx sources, we find an increase of isotope values in comparison to historical data. We explore the role of land-based N sources, because backward trajectories reveal a correlation of higher δ(15)N to air mass origin from industrialized areas. Nowadays isotopically enriched NOx of coal-fired power plants using selective catalytic converters and land-based vehicle emissions, which use same technology, are apparently the main driver of rising δ(15)N values in nitrate deposition.

  3. Deciphering the Atmospheric Composition of WASP-12b: A Comprehensive Analysis of its Dayside Emission

    CERN Document Server

    Stevenson, Kevin B; Madhusudhan, Nikku; Harrington, Joseph

    2014-01-01

    WASP-12b was the first planet reported to have a carbon-to-oxygen ratio (C/O) greater than one in its dayside atmosphere. However, recent work to further characterize its atmosphere and confirm its composition has led to incompatible measurements and divergent conclusions. Additionally, the recent discovery of stellar binary companions ~1" from WASP-12 further complicates the analyses and subsequent interpretations. We present a uniform analysis of all available Hubble and Spitzer Space Telescope secondary-eclipse data, including previously-unpublished Spitzer measurements at 3.6 and 4.5 microns. The primary controversy in the literature has centered on the value and interpretation of the eclipse depth at 4.5 microns. Our new measurements and analyses confirm the shallow eclipse depth in this channel, as first reported by Campo and collaborators and used by Madhusudhan and collaborators to infer a carbon-rich composition. To explain WASP-12b's observed dayside emission spectrum, we implemented several recent ...

  4. Feedbacks of Composition and Neutral Density Changes on the Structure of the Cusp Density Anomaly

    Science.gov (United States)

    Brinkman, D. G.; Walterscheid, R. L.; Clemmons, J. H.

    2015-12-01

    The Earth's magnetospheric cusp provides direct access of energetic particles to the thermosphere. These particles produce ionization and kinetic (particle) heating of the atmosphere. The increased ionization coupled with enhanced electric fields in the cusp produces increased Joule heating and ion drag forcing. These energy inputs cause large wind and temperature changes in the cusp region. Measurements by the CHAMP satellite (460-390- km altitude) have shown strongly enhanced density in the cusp region. The Streak mission (325-123 km), on the other hand, showed a relative depletion. The atmospheric response in the cusp can be sensitive to composition and neutral density changes. In response to heating in the cusp, air of heavier mean molecular weight is brought up from lower altitudes significantly affecting pressure gradients. This opposes the effects of temperature change due to heating and in-turn affects the density and winds produced in the cusp. Also changes in neutral density change the interaction between precipitating particles and the atmosphere and thus change heating rates and ionization in the region affected by cusp precipitation. In this study we assess the sensitivity of the wind and neutral density structure in the cusp region to changes in the mean molecular weight induced by neutral dynamics, and the changes in particle heating rates and ionization which result from changes in neutral density. We use a high resolution two-dimensional time-dependent nonhydrostatic nonlinear dynamical model where inputs can be systematically altered. The resolution of the model allows us to examine the complete range of cusp widths. We compare the current simulations to observations by CHAMP and Streak. Acknowledgements: This research was supported by The Aerospace Corporation's Technical Investment program

  5. The carbon isotopic compositions of Non-methane Hydrocarbons in atmosphere

    Institute of Scientific and Technical Information of China (English)

    PENG Lin; ZHANG HuiMin; REN ZhaoFang; MU Ling; SHI RuiLiang; CHANG LiPing; LI Fan

    2009-01-01

    Carbon isotopic compositions of atmospheric Non-methane Hydrocarbons (NMHCs) in the urban areas of Taiyuan and Lanzhou in summer were reported and the sources of NMHCs are discussed.Carbon isotopic ratios (δ13C) of vehicle exhaust,coal-combustion exhaust,fuel volatiles and cooking exhaust were also measured with thermal desorption-gas chromatography-isotope ratio-mass spectrometry (TD-GC-IR-MS).δ13C values of NMHCs in the urban areas of Lanzhou and Taiyuan range from -32.3‰ to -22.3‰ and from -32.8‰ to -18.1‰.δ13C values of vehicle exhaust,coal-combustion exhaust,fuel volatiles and cooking exhaust are -32.5‰--21.7‰,-24.5‰--22.3‰,-32.5%--27.4‰ and -31.6‰--24.5‰,respectively.The data indicate that vehicle exhaust and cooking exhaust make a significant contribution to the atmospheric NMHCs.Therefore,to reduce emissions of vehicle exhaust and cook-ing exhaust is critical for controlling atmospheric NMHCs pollution in summer.

  6. Compositional variability of the Venusian atmosphere above the clouds: sulphur dioxide and carbon monoxide

    Science.gov (United States)

    Marcq, Emmanuel; Belyaev, Denis; Lellouch, Emmanuel; Encrenaz, Therese; Montmessin, Franck; Bertaux, Jean-Loup

    The layers of the Venusian atmosphere located at cloud top level is a complex transitional region where intense solar radiation interacts with a fairly dense gaseous medium and particulate matter - ultimately, the cloud particles themselves are a by-product of this interaction. In a stark contrast with the lowermost troposphere, spatial and temporal variations in temperature and composition are easily noticeable. In this talk we will focus on two gaseous species, carbon monoxide (CO) and sulphur dioxide (SO _{2}), whose sources and sinks are reversed: whereas carbon monoxide is produced by photo-dissociation of the main atmospheric constituent CO _{2} and oxidised below the clouds, SO _{2} is destroyed by UV solar radiation above the clouds and replenished from the lower atmosphere. Yet, these two species exhibit very different variation patterns. SO _{2} temporal variations range from very rapid (within a few hours) and large (by a relative factor exceeding 10) variations to secular phases of increases and decreases spanning decades. Its average latitudinal distribution ranges from a decrease with increasing latitude during SO _{2}-rich phases and a possible reversal during SO _{2}-poor phases. In contrast, CO does not exhibit significant secular, nor short-term variability, but clear horizontal trends have been measured, both with respect to latitude and local solar time.

  7. EFFECTS OF ATMOSPHERIC H2S ON THIOL COMPOSITION OF CROP PLANTS

    NARCIS (Netherlands)

    BUWALDA, F; DE KOK, LJ; Stulen, I.

    1993-01-01

    Exposure of crop plants to H2S resulted in an increase in thiol level and a change in the composition of the thiol pool. Non-leguminous species accumulated cysteine and glutathione in the light, whereas in the dark, substantial amounts of gamma-glutamyl-cysteine were also detected. In leguminous spe

  8. Isotopic composition for source identification of mercury in atmospheric fine particles

    Science.gov (United States)

    Huang, Qiang; Chen, Jiubin; Huang, Weilin; Fu, Pingqing; Guinot, Benjamin; Feng, Xinbin; Shang, Lihai; Wang, Zhuhong; Wang, Zhongwei; Yuan, Shengliu; Cai, Hongming; Wei, Lianfang; Yu, Ben

    2016-09-01

    The usefulness of mercury (Hg) isotopes for tracing the sources and pathways of Hg (and its vectors) in atmospheric fine particles (PM2.5) is uncertain. Here, we measured Hg isotopic compositions in 30 potential source materials and 23 PM2.5 samples collected in four seasons from the megacity Beijing (China) and combined the seasonal variation in both mass-dependent fractionation (represented by the ratio 202Hg / 198Hg, δ202Hg) and mass-independent fractionation of isotopes with odd and even mass numbers (represented by Δ199Hg and Δ200Hg, respectively) with geochemical parameters and meteorological data to identify the sources of PM2.5-Hg and possible atmospheric particulate Hg transformation. All PM2.5 samples were highly enriched in Hg and other heavy metals and displayed wide ranges of both δ202Hg (-2.18 to 0.51 ‰) and Δ199Hg (-0.53 to 0.57 ‰), as well as small positive Δ200Hg (0.02 to 0.17 ‰). The results indicated that the seasonal variation in Hg isotopic composition (and elemental concentrations) was likely derived from variable contributions from anthropogenic sources, with continuous input due to industrial activities (e.g., smelting, cement production and coal combustion) in all seasons, whereas coal combustion dominated in winter and biomass burning mainly found in autumn. The more positive Δ199Hg of PM2.5-Hg in spring and early summer was likely derived from long-range-transported Hg that had undergone extensive photochemical reduction. The study demonstrated that Hg isotopes may be potentially used for tracing the sources of particulate Hg and its vectors in the atmosphere.

  9. Effects of Climate Change and Shifts in Forest Composition on Forest Net Primary Production

    Institute of Scientific and Technical Information of China (English)

    Jyh-Min Chiang; Louts R. Iverson; Anantha Prasad; Kim J. Brown

    2008-01-01

    Forests are dynamic in both structure and species composition, and these dynamics are strongly Influenced by climate.However, the net effects of future tree species composition on net primary production (NPP) are not well understood. The objective of this work was to model the potential range shifts of tree species (DISTRIB Model) and predict their impacts on NPP (PnET-Ⅱ Model) that will be associated with alterations in species composition. We selected four 200 × 200 km areas In Wisconsin, Maine, Arkansas, and the Ohio-West Virginia area, representing focal areas of potential species range shifts. PnET-Ⅱ model simulations were carried out assuming that all forests achieved steady state, of which the species compositions were predicted by DISTRIB model with no migration limitation. The total NPP under the current climate ranged from 552 to 908 g C/m2 per year. The effects of potential species redistributions on NPP were moderate (-12% to +8%) compared with the influence of future climatic changes (-60% to +25%). The direction and magnitude of climate change effects on NPP were largely dependent on the degree of warming and water balance. Thus, the magnitude of future climate change can affect the feedback system between the atmosphere and biosphere.

  10. Effects of climate change on plant population growth rate and community composition change.

    Science.gov (United States)

    Chang, Xiao-Yu; Chen, Bao-Ming; Liu, Gang; Zhou, Ting; Jia, Xiao-Rong; Peng, Shao-Lin

    2015-01-01

    The impacts of climate change on forest community composition are still not well known. Although directional trends in climate change and community composition change were reported in recent years, further quantitative analyses are urgently needed. Previous studies focused on measuring population growth rates in a single time period, neglecting the development of the populations. Here we aimed to compose a method for calculating the community composition change, and to testify the impacts of climate change on community composition change within a relatively short period (several decades) based on long-term monitoring data from two plots-Dinghushan Biosphere Reserve, China (DBR) and Barro Colorado Island, Panama (BCI)-that are located in tropical and subtropical regions. We proposed a relatively more concise index, Slnλ, which refers to an overall population growth rate based on the dominant species in a community. The results indicated that the population growth rate of a majority of populations has decreased over the past few decades. This decrease was mainly caused by population development. The increasing temperature had a positive effect on population growth rates and community change rates. Our results promote understanding and explaining variations in population growth rates and community composition rates, and are helpful to predict population dynamics and population responses to climate change.

  11. Effects of climate change on plant population growth rate and community composition change.

    Directory of Open Access Journals (Sweden)

    Xiao-Yu Chang

    Full Text Available The impacts of climate change on forest community composition are still not well known. Although directional trends in climate change and community composition change were reported in recent years, further quantitative analyses are urgently needed. Previous studies focused on measuring population growth rates in a single time period, neglecting the development of the populations. Here we aimed to compose a method for calculating the community composition change, and to testify the impacts of climate change on community composition change within a relatively short period (several decades based on long-term monitoring data from two plots-Dinghushan Biosphere Reserve, China (DBR and Barro Colorado Island, Panama (BCI-that are located in tropical and subtropical regions. We proposed a relatively more concise index, Slnλ, which refers to an overall population growth rate based on the dominant species in a community. The results indicated that the population growth rate of a majority of populations has decreased over the past few decades. This decrease was mainly caused by population development. The increasing temperature had a positive effect on population growth rates and community change rates. Our results promote understanding and explaining variations in population growth rates and community composition rates, and are helpful to predict population dynamics and population responses to climate change.

  12. Structuro-functional changes in the placenta as a result of exposure to atmospheric pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Bonashevskaia, T.I.; Lamentova, T.G.; Shmakov, G.S.; Nikolaeva, E.G.; Suslova, V.M.

    1985-02-01

    Under the influence of atmospheric pollutions certain structural-functional changes take place in placenta: terminal villi per stipulated square unite, villi with desquamated epithelium, with dilated vessels, with deposition of fibrinoid masses, with plasmodial buds increase in number; section area occupied by epithelial layer decreases; RNA concentration and histoenzymatic activity change in the latter.

  13. Seasonal variations of triple oxygen isotopic compositions of atmospheric sulfate, nitrate, and ozone at Dumont d'Urville, coastal Antarctica

    Science.gov (United States)

    Ishino, Sakiko; Hattori, Shohei; Savarino, Joel; Jourdain, Bruno; Preunkert, Susanne; Legrand, Michel; Caillon, Nicolas; Barbero, Albane; Kuribayashi, Kota; Yoshida, Naohiro

    2017-03-01

    Triple oxygen isotopic compositions (Δ17O = δ17O - 0.52 × δ18O) of atmospheric sulfate (SO42-) and nitrate (NO3-) in the atmosphere reflect the relative contribution of oxidation pathways involved in their formation processes, which potentially provides information to reveal missing reactions in atmospheric chemistry models. However, there remain many theoretical assumptions for the controlling factors of Δ17O(SO42-) and Δ17O(NO3-) values in those model estimations. To test one of those assumption that Δ17O values of ozone (O3) have a flat value and do not influence the seasonality of Δ17O(SO42-) and Δ17O(NO3-) values, we performed the first simultaneous measurement of Δ17O values of atmospheric sulfate, nitrate, and ozone collected at Dumont d'Urville (DDU) Station (66°40' S, 140°01' E) throughout 2011. Δ17O values of sulfate and nitrate exhibited seasonal variation characterized by minima in the austral summer and maxima in winter, within the ranges of 0.9-3.4 and 23.0-41.9 ‰, respectively. In contrast, Δ17O values of ozone showed no significant seasonal variation, with values of 26 ± 1 ‰ throughout the year. These contrasting seasonal trends suggest that seasonality in Δ17O(SO42-) and Δ17O(NO3-) values is not the result of changes in Δ17O(O3), but of the changes in oxidation chemistry. The trends with summer minima and winter maxima for Δ17O(SO42-) and Δ17O(NO3-) values are caused by sunlight-driven changes in the relative contribution of O3 oxidation to the oxidation by HOx, ROx, and H2O2. In addition to that general trend, by comparing Δ17O(SO42-) and Δ17O(NO3-) values to ozone mixing ratios, we found that Δ17O(SO42-) values observed in spring (September to November) were lower than in fall (March to May), while there was no significant spring and fall difference in Δ17O(NO3-) values. The relatively lower sensitivity of Δ17O(SO42-) values to the ozone mixing ratio in spring compared to fall is possibly explained by (i) the

  14. Dynamic responses of atmospheric carbon dioxide concentration to global temperature changes between 1850 and 2010

    Science.gov (United States)

    Wang, Weile; Nemani, Ramakrishna

    2016-02-01

    Changes in Earth's temperature have significant impacts on the global carbon cycle that vary at different time scales, yet to quantify such impacts with a simple scheme is traditionally deemed difficult. Here, we show that, by incorporating a temperature sensitivity parameter (1.64 ppm yr-1 °C-1) into a simple linear carbon-cycle model, we can accurately characterize the dynamic responses of atmospheric carbon dioxide (CO2) concentration to anthropogenic carbon emissions and global temperature changes between 1850 and 2010 ( r 2 > 0.96 and the root-mean-square error reservoir (~12 year) approximates the long-term temperature sensitivity of global atmospheric CO2 concentration (~15 ppm °C-1), generally consistent with previous estimates based on reconstructed CO2 and climate records over the Little Ice Age. Our results suggest that recent increases in global surface temperatures, which accelerate the release of carbon from the surface reservoirs into the atmosphere, have partially offset surface carbon uptakes enhanced by the elevated atmospheric CO2 concentration and slowed the net rate of atmospheric CO2 sequestration by global land and oceans by ~30% since the 1960s. The linear modeling framework outlined in this paper thus provides a useful tool to diagnose the observed atmospheric CO2 dynamics and monitor their future changes.

  15. Dynamics of Soil Organic Carbon Under Uncertain Climate Change and Elevated Atmospheric CO2

    Institute of Scientific and Technical Information of China (English)

    LIN Zhong-Bing; ZHANG Ren-Duo

    2012-01-01

    Climate change and elevated atmospheric CO2 should affect the dynamics of soil organic carbon (SOC).SOC dynamics under uncertain patterns of climate warming and elevated atmospheric CO2 as well as with different soil erosion extents at Nelson Farm during 1998-2100 were simulated using stochastic modelling.Results based on numerous simulations showed that SOC decreased with elevated atmospheric temperature but increased with atmospheric CO2 concentration.Therefore,there was a counteract effect on SOC dynamics between climate warming and elevated CO2.For different soil erosion extents,warming 1 ℃ and elevated atmospheric CO2 resulted in SOC increase at least 15%,while warming 5 ℃ and elevated CO2 resulted in SOC decrease more than 29%.SOCpredictions with uncertainty assessment were conducted for different scenarios of soil erosion,climate change,and elevated CO2.Statistically,SOC decreased linearly with the probability.SOC also decreased with time and the degree of soil erosion.For example,in 2100 with a probability of 50%,SOC was 1617,1 167,and 892 g m-2,respectively,for no,minimum,and maximum soil erosion.Under climate warming 5 ℃ and elevated CO2,the soil carbon pools became a carbon source to the atmosphere (P > 95%).The results suggested that stochastic modelling could be a useful tool to predict future SOC dynamics under uncertain climate change and elevated CO2.

  16. The impact of enhanced atmospheric carbon dioxide on yield, proximate composition, elemental concentration, fatty acid and vitamin C contents of tomato (Lycopersicon esculentum).

    Science.gov (United States)

    Khan, Ikhtiar; Azam, Andaleeb; Mahmood, Abid

    2013-01-01

    The global average temperature has witnessed a steady increase during the second half of the twentieth century and the trend is continuing. Carbon dioxide, a major green house gas is piling up in the atmosphere and besides causing global warming, is expected to alter the physico-chemical composition of plants. The objective of this work was to evaluate the hypothesis that increased CO(2) in the air is causing undesirable changes in the nutritional composition of tomato fruits. Two varieties of tomato (Lycopersicon esculentum) were grown in ambient (400 μmol mol(-1)) and elevated (1,000 μmol mol(-1)) concentration of CO(2) under controlled conditions. The fruits were harvested at premature and fully matured stages and analyzed for yield, proximate composition, elemental concentration, fatty acid, and vitamin C contents. The amount of carbohydrates increased significantly under the enhanced CO(2) conditions. The amount of crude protein and vitamin C, two important nutritional parameters, decreased substantially. Fatty acid content showed a mild decrease with a slight increase in crude fiber. Understandably, the effect of enhanced atmospheric CO(2) was more pronounced at the fully matured stage. Mineral contents of the fruit samples changed in an irregular fashion. Tomato fruit has been traditionally a source of vitamin C, under the experimental conditions, a negative impact of enhanced CO(2) on this source of vitamin C was observed. The nutritional quality of both varieties of tomato has altered under the CO(2) enriched atmosphere.

  17. Stress-induced changes in wheat grain composition and quality.

    Science.gov (United States)

    Ashraf, M

    2014-01-01

    Abiotic stresses such as drought, salinity, waterlogging, and high temperature cause a myriad of changes in the metabolism of plants, and there is a lot of overlap in these changes in plants in response to different stresses such as drought and salinity. These stress-induced metabolic changes cause impaired crop growth thereby resulting in poor yield. The metabolic changes taking place in several plant species due to a particular abiotic stress have been revealed from the whole plant to the molecular level by researchers, but most studies have focused on organs such as leaf, stem, and root. Information on such stress-induced changes in seed or grains is infrequent in the literature. From the information that is available, it is now evident that abiotic stress can induce considerable changes in the composition and quality of cereal grains including those of wheat, the premier staple food crop in the world. Thus, the present review discusses how far different types of stresses, mainly salinity, drought, high temperature, and waterlogging, can alter the wheat grain composition and quality. By fully uncovering the stress-induced changes in the nutritional values of wheat grains it would be possible to establish whether balanced supplies of essential nutrients are available to the human population from the wheat crop grown on stress-affected areas.

  18. The effect of atmosphere composition in plasma nitrogenation of Sm2Fe17

    Science.gov (United States)

    Ardisson, J. D.; Araujo, R. C.; Macedo, W. A. A.; Persiano, A. I. C.; Gama, S.

    2004-05-01

    The change on the structural and magnetic properties of the Sm2Fe17 compound as the ratio of H2/N2 forming the mixture of the atmosphere in a plasma chamber used to nitride this compound varied, was investigated by Mössbauer spectroscopy and X-ray diffraction. Our results show that the increase of the hydrogen concentration in the mixed H2/N2 atmosphere reduces the formation of the nitrogen-rich phases, Sm2Fe17N8 and Sm2Fe17N11 and increases the formation of the Sm2Fe17N3 phase, whose maximum values are obtained for 70% H2 in the gas mixture.

  19. Chemical Composition of Atmospheric Aerosols Above a Pristine South East Asian Rainforest

    Science.gov (United States)

    Robinson, N. H.; Allan, J. D.; Williams, P. I.; Coe, H.; Hamilton, J.; Chen, Q.; Martin, S.; Trembath, J.

    2009-04-01

    The tropics emit a huge amount of volatile organic compounds (VOCs) into the Earth's atmosphere. The processes by which these gases are oxidised to form secondary organic aerosol (SOA) are currently not well understood or quantified. Intensive field measurements were carried out as part of the Oxidant and Particle Photochemical Processes (OP3) and the Aerosol Coupling in the Earth System (ACES) projects around pristine rainforest in Malaysian Borneo. This is the first campaign of its type in a South East Asian rainforest. We present detailed organic aerosol composition measurements made using an Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS) at Bukit Atur, a Global Atmosphere Watch site located in the Danum Valley Conservation Area. This is a state-of-the-art field deployable instrument that can provide real time composition, mass loading and aerodynamic particle sizing information. In addition, the mass spectral resolution is sufficient to perform an analysis of the elemental composition of the organic species present. Other tools such as positive matrix factorisation (PMF) have been used to help assess the relative source contributions to the organic aerosol. A suite of supporting aerosol and gas phase measurements were made, including size resolved number concentration measurements with Differential Mobility Particle Sizer (DMPS), as well as absorption measurements made with a Multi-Angle Absorption Photometer (MAAP). The ground site data are compared with Aerodyne Compact Time of Flight Aerosol Mass Spectrometer (C-ToF-AMS) measurements made on the UK Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 research aircraft. Airborne measurements were made above pristine rainforest surrounding the Danum Valley site, as well as nearby oil palm agricultural sites and palm oil rendering plants. Airborne hygroscopicity was measured using a Droplet Measurement Technology Cloud Condensation Nuclei counter (DMT CCN counter) in

  20. Stable carbon isotopes of C3 plant resins and ambers record changes in atmospheric oxygen since the Triassic

    Science.gov (United States)

    Tappert, Ralf; McKellar, Ryan C.; Wolfe, Alexander P.; Tappert, Michelle C.; Ortega-Blanco, Jaime; Muehlenbachs, Karlis

    2013-11-01

    Estimating the partial pressure of atmospheric oxygen (pO2) in the geological past has been challenging because of the lack of reliable proxies. Here we develop a technique to estimate paleo-pO2 using the stable carbon isotope composition (δ13C) of plant resins-including amber, copal, and resinite-from a wide range of localities and ages (Triassic to modern). Plant resins are particularly suitable as proxies because their highly cross-linked terpenoid structures allow the preservation of pristine δ13C signatures over geological timescales. The distribution of δ13C values of modern resins (n = 126) indicates that (a) resin-producing plant families generally have a similar fractionation behavior during resin biosynthesis, and (b) the fractionation observed in resins is similar to that of bulk plant matter. Resins exhibit a natural variability in δ13C of around 8‰ (δ13C range: -31‰ to -23‰, mean: -27‰), which is caused by local environmental and ecological factors (e.g., water availability, water composition, light exposure, temperature, nutrient availability). To minimize the effects of local conditions and to determine long-term changes in the δ13C of resins, we used mean δ13C values (δ13Cmeanresin) for each geological resin deposit. Fossil resins (n = 412) are generally enriched in 13C compared to their modern counterparts, with shifts in δ13Cmeanresin of up to 6‰. These isotopic shifts follow distinctive trends through time, which are unrelated to post-depositional processes including polymerization and diagenesis. The most enriched fossil resin samples, with a δ13Cmeanresin between -22‰ and -21‰, formed during the Triassic, the mid-Cretaceous, and the early Eocene. Experimental evidence and theoretical considerations suggest that neither change in pCO2 nor in the δ13C of atmospheric CO2 can account for the observed shifts in δ13Cmeanresin. The fractionation of 13C in resin-producing plants (Δ13C), instead, is primarily influenced by

  1. Effect of staining agents on color change of composites

    Directory of Open Access Journals (Sweden)

    Mateus Rodrigues Tonetto

    2012-09-01

    Full Text Available Introduction: Composite resins are materials that can present color changing when exposed to pigments. Objective: The aim of this study was to evaluate, in vitro, the color changing of composites after immersion in different substances for different periods. Material and methods: Two microhybrid composite resins: Charisma (Heraeus – Kulzer and Opallis (FGM were used. Red wine and acai pulp were also used as immersion medium. For this study, 32 specimens with 10 mm of diameter and 2 mm of thickness were used, divided into 4 groups: Group 1 – Opallis composite immersed in red wine solution; Group 2 – Opallis composite immersed in acai berry pulp solution; Group 3 – Charisma composite immersed in red wine solution; Group 4 – Charisma composite immersed in acai berry pulp solution. The specimens were evaluated in the following time periods: T0 – baseline, T1 – 24 hours, T2 – 48 hours, T3 – 72 hours and T4 – 96 hours. For the assessment of staining, a spectrophotometer for colorimetry was used (Color Guide 45 / 0, PCB 6807 BYK-Gardner Gerestsried GmBH, Germany, and the values obtained were transferred to a computer and recorded according to CIELAB system. Results: The data were evaluated using Kruskal- Wallis non-parametric tests with the following �E mean values for the immersion periods of 24, 48, 72 and 96 hours, respectively: G1 – 7.35, 7.84, 9.04,10.48; G2 – 2.92, 4.15, 4.30, 4.64; G3 – 3.14, 7.35, 8.13, 8.43, G4 – 4.49, 5.99, 6.92, 6.76. Conclusion: Red wine showed a higher tendency toward altering the composite color than acai berry pulp. In addition, no significant difference was found concerning to the behavior of the two composite resins. Concerning to the immersion time periods, significant differences were only observed among the groups in the 24 hour time period.

  2. Improvement of Strength Characteristics of Aerospace Fiber Reinforced Composite Materials using Atmospheric Pressure Plasma-Graft Polymerization Treatment

    Science.gov (United States)

    Aoi, Tatsuji; Kuroki, Tomoyuki; Tahara, Mitsuru; Okubo, Masaaki

    The atmospheric pressure nonthermal plasma-graft polymerization treatment is applied for the surface modification of the organic fibers in order to enhance the strength of the aerospace structural composite material consisting of the laminated textiles. The influence of the treatment on the composite materials' strength properties is examined. As a result, the plasma-graft polymerization surface treatment is effective for the compression and bend of the composite materials. Because the interfacial bonding between each fiber and matrix resin is strengthened by the treatment, the strengths of the composite materials are increased.

  3. Thermal Stress Effect on Density Changes of Hemp Hurds Composites

    Directory of Open Access Journals (Sweden)

    Schwarzova Ivana

    2016-12-01

    Full Text Available The aim of this article is to study the behavior of prepared biocomposites based on hemp hurds as a filling agent in composite system. In addition to the filler and water, an alternative binder, called MgO-cement was used. For this objective were prepared three types of samples; samples based on untreated hemp hurds as a referential material and samples based on chemically (with NaOH solution and physically (by ultrasonic procedure treated hemp hurds. The thermal stress effect on bulk density changes of hemp hurds composites was monitored. Gradual increase in temperature led to composites density reduction of 30-40 %. This process is connected with mass loss of the adsorbed moisture and physically bound water and also with degradation of organic compounds present in hemp hurds aggregates such as pectin, hemicelluloses and cellulose. Therefore the changes in the chemical composition of treated hemp hurds in comparison to original sample and its thermal decomposition were also studied.

  4. Nitrogen metastable (N2(A3 Σu + )) in a cold argon atmospheric pressure plasma jet: Shielding and gas composition

    Science.gov (United States)

    Iseni, Sylvain; Bruggeman, Peter J.; Weltmann, Klaus-Dieter; Reuter, Stephan

    2016-05-01

    N 2 ( A 3 Σu + ) metastable species are detected and measured in a non-equilibrium atmospheric pressure plasma jet by laser induced fluorescence. A shielding device is used to change the ambient conditions additionally to the feeding gas composition. Varying the amount of N2 and air admixed to the feeding gas as well as changing the shielding gas from N2 to air reveals that the highest N 2 ( A 3 Σu + ) is achieved in the case of air admixtures in spite of the enhanced collisional quenching due to the presence of O2. The reasons for these observations are discussed in detail.

  5. Advances on the Responses of Root Dynamics to Increased Atmospheric CO2 and Global Climate Change

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Plant roots dynamics responses to elevated atmospheric CO2 concentration, increased temperature and changed precipitation can be a key link between plant growth and long-term changes in soil organic matter and ecosystem carbon balance. This paper reviews some experiments and hypotheses developed in this area, which mainly include plant fine roots growth, root turnover, root respiration and other root dynamics responses to elevated CO2 and global climate change. Some recent new methods of studying root systems were also discussed and summarized. It holds herein that the assemblage of information about root turnover patterns, root respiration and other dynamic responses to elevated atmospheric CO2 and global climatic change can help to better understand and explore some new research areas. In this paper, some research challenges in the plant root responses to the elevated CO2 and other environmental factors during global climate change were also demonstrated.

  6. Composition of thermodestruction products of biologically active compounds polluting the atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Dmitriyev, M.T.; Rastyannikov, Y.G.; Sotnikov, Y.Y.; Volkov, S.A.

    1981-01-01

    The most promising method of removal of biologically active compounds such as microorganisms, antibiotics, food and other household waste from industrial waste gases is to destroy them by thermal destruction including burning. In this case, products of thermodestruction enter into the atmosphere along with carbon dioxide and steam and can unfavorably affect the population. Thus, mass spectrometric analyses have determined in the waste gases of antibiotics production aldehydes and ketones (croton- and adipalaldehydes, acetone), alcohols (propanol and butanol), amines, unsaturated and aromatic hydrocarbons. The composition of thermodestruction products of biologically active compounds was identified by their pyrolysis at 700/sup 0/C for 2 min. in the presence of air. The main components were proteins and amino acids. The products of pyrolysis were analyzed by chromato-mass-spectrometric and gas-chromatographic methods by means of a two-flame thermionic detector. No significant difference between the thermodestruction products of proteins and amino acids was found. Many of detected substances can be not only toxic but also emit strong unpleasant odors. The studies revealed toxic substances that pollute the atmospheric air during removal of biologically-active compounds from waste gases.

  7. Ground-based simulation of the Earth's upper atmosphere oxygen impact on polymer composites with nanosized fillers

    Science.gov (United States)

    Novikov, Lev; Chernik, Vladimir; Voronina, Ekaterina; Chechenin, Nikolay; Samokhina, Maria S.; Bondarenko, Gennady G.; Gaidar, Anna I.; Vorobyeva, Ekaterina A.; Petrov, Dmitrii V.; Chirskaya, Natalia P.

    The improvement of durability of polymer composites to the space environment impact is a very important task because these materials are considered currently as very promising type of materials for aerospace engineering. By embedding various nanosized fillers into a polymer matrix it is possible to obtain composites with required mechanical, thermal, electrical and optic properties. However, while developing such materials for operation in low Earth orbits (LEO), it is necessary to study thoroughly their durability to the impact of atomic oxygen (AO) of the Earth’s upper atmosphere, because AO is the main factor that causes erosion and damage of spacecraft surface materials in LEO. Ground-based simulation of AO impact on polymer composites was performed on a magnetoplasmadynamic accelerator developed at Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University. Polymer composite samples which were prepared as films of 30-50 mum thickness with different amount (3-20 wt%) of various inorganic and organic nanofillers including nanoparticles of metal oxides and carbides as well as polyethoxysiloxanes and carbon nanotubes (CNTs), were exposed to hyperthermal AO flow, and mass losses of samples were estimated. Changes in the structure of composite surface and in material optical properties were studied. The experiments demonstrated that embedding nanosized fillers into a polymer matrix can significantly reduced mass losses, and the good dispersion of fillers improves AO durability in comparison with initial polymers [1]. The computer simulation within the developed 2D Monte-Carlo model demonstrated a good agreement with the experimental data [2]. Special attention was given to the study of AO impact on aligned multiwalled CNTs and CNT-based composites [3]. Some results of computer simulation of hyperthermal oxygen atom interaction with CNT and graphene as well as with polymers are presented to discuss elementary processes which occur in nanostructures

  8. Microencapsulated Phase Change Composite Materials for Energy Efficient Buildings

    Science.gov (United States)

    Thiele, Alexander

    This study aims to elucidate how phase change material (PCM)-composite materials can be leveraged to reduce the energy consumption of buildings and to provide cost savings to ratepayers. Phase change materials (PCMs) can store thermal energy in the form of latent heat when subjected to temperatures exceeding their melting point by undergoing a phase transition from solid to liquid state. Reversibly, PCMs can release this thermal energy when the system temperature falls below their solidification point. The goal in implementing composite PCM walls is to significantly reduce and time-shift the maximum thermal load on the building in order to reduce and smooth out the electricity demand for heating and cooling. This Ph.D. thesis aims to develop a set of thermal design methods and tools for exploring the use of PCM-composite building envelopes and for providing design rules for their practical implementation. First, detailed numerical simulations were used to show that the effective thermal conductivity of core-shell-matrix composites depended only on the volume fraction and thermal conductivity of the constituent materials. The effective medium approximation reported by Felske (2004) was in very good agreement with numerical predictions of the effective thermal conductivity. Second, a carefully validated transient thermal model was used to simulate microencapsulated PCM-composite walls subjected to diurnal or annual outdoor temperature and solar radiation flux. It was established that adding microencapsulated PCM to concrete walls both substantially reduced and delayed the thermal load on the building. Several design rules were established, most notably, (i) increasing the volume fraction of microencapsulated PCM within the wall increases the energy savings but at the potential expense of mechanical properties [1], (ii) the phase change temperature leading to the maximum energy and cost savings should equal the desired indoor temperature regardless of the climate

  9. Atmospheric aerosols in Amazonia and land use change: from natural biogenic to biomass burning conditions.

    Science.gov (United States)

    Artaxo, Paulo; Rizzo, Luciana V; Brito, Joel F; Barbosa, Henrique M J; Arana, Andrea; Sena, Elisa T; Cirino, Glauber G; Bastos, Wanderlei; Martin, Scot T; Andreae, Meinrat O

    2013-01-01

    In the wet season, a large portion of the Amazon region constitutes one of the most pristine continental areas, with very low concentrations of atmospheric trace gases and aerosol particles. However, land use change modifies the biosphere-atmosphere interactions in such a way that key processes that maintain the functioning of Amazonia are substantially altered. This study presents a comparison between aerosol properties observed at a preserved forest site in Central Amazonia (TT34 North of Manaus) and at a heavily biomass burning impacted site in south-western Amazonia (PVH, close to Porto Velho). Amazonian aerosols were characterized in detail, including aerosol size distributions, aerosol light absorption and scattering, optical depth and aerosol inorganic and organic composition, among other properties. The central Amazonia site (TT34) showed low aerosol concentrations (PM2.5 of 1.3 +/- 0.7 microg m(-3) and 3.4 +/- 2.0 microg m(-3) in the wet and dry seasons, respectively), with a median particle number concentration of 220 cm(-3) in the wet season and 2200 cm(-3) in the dry season. At the impacted site (PVH), aerosol loadings were one order of magnitude higher (PM2.5 of 10.2 +/- 9.0 microg m(-3) and 33.0 +/- 36.0 microg m(-3) in the wet and dry seasons, respectively). The aerosol number concentration at the impacted site ranged from 680 cm(-3) in the wet season up to 20 000 cm(-3) in the dry season. An aerosol chemical speciation monitor (ACSM) was deployed in 2013 at both sites, and it shows that organic aerosol account to 81% to the non-refractory PM1 aerosol loading at TT34, while biomass burning aerosols at PVH shows a 93% content of organic particles. Three years of filter-based elemental composition measurements shows that sulphate at the impacted site decreases, on average, from 12% of PM2.5 mass during the wet season to 5% in the dry season. This result corroborates the ACSM finding that the biomass burning contributed overwhelmingly to the organic

  10. 10-year record of atmospheric composition in the high Himalayas: source, transport and impact

    Science.gov (United States)

    Bonasoni, Paolo; Laj, Paolo; Marinoni, Angela; Cristofanelli, Paolo; Maione, Michela; Putero, Davide; Calzolari, Francescopiero; Decesari, Stefano; Facchini, Maria Cristina; Fuzzi, Sandro; Gobbi, Gianpaolo; Sellegri, Karine; Verza, Gianpietro; Vuillermoz, Elisa; Arduini, Jgor

    2016-04-01

    occurrence of pollution transport and high rate of new particle formation events in this region. Here we provide an overview of the main scientific results obtained during these ten years of research. In particular, we will discuss the impact of atmospheric transport and monsoon variability on atmospheric composition by disentangling the role played by mountain breeze system and synoptic-scale transport. We will provide specific information about the role of stratospheric intrusions, long-range mineral dust transport and open biomass burning emissions in determining the variability of ozone, aerosol and equivalent black carbon concentrations. The effect of particle nucleation processes on aerosol number concentrations will be shown. Finally, we discuss the climatic impact of aerosols observed at NCO-P both in terms of direct atmospheric radiative forcing and black carbon deposition on Himalayan snow.

  11. Building oceanographic and atmospheric observation networks by composition: unmanned vehicles, communication networks, and planning and execution control frameworks

    Science.gov (United States)

    Sousa, J. T.; Pinto, J.; Martins, R.; Costa, M.; Ferreira, F.; Gomes, R.

    2014-12-01

    The problem of developing mobile oceanographic and atmospheric observation networks (MOAO) with coordinated air and ocean vehicles is discussed in the framework of the communications and control software tool chain developed at Underwater Systems and Technologies Laboratory (LSTS) from Porto University. This is done with reference to field experiments to illustrate key capabilities and to assess future MOAO operations. First, the motivation for building MOAO by "composition" of air and ocean vehicles, communication networks, and planning and execution control frameworks is discussed - in networked vehicle systems information and commands are exchanged among multiple vehicles and operators, and the roles, relative positions, and dependencies of these vehicles and operators change during operations. Second, the planning and execution control framework developed at LSTS for multi-vehicle systems is discussed with reference to key concepts such as autonomy, mixed-initiative interactions, and layered organization. Third, the LSTS tool software tool chain is presented to show how to develop MOAO by composition. The tool chain comprises the Neptus command and control framework for mixed initiative interactions, the underlying IMC messaging protocol, and the DUNE on-board software. Fourth, selected LSTS operational deployments illustrate MOAO capability building. In 2012 we demonstrated the use of UAS to "ferry" data from UUVs located beyond line of sight (BLOS). In 2013 we demonstrated coordinated observations of coastal fronts with small UAS and UUVs, "bent" BLOS through the use of UAS as communication relays, and UAS tracking of juvenile hammer-head sharks. In 2014 we demonstrated UUV adaptive sampling with the closed loop controller of the UUV residing on a UAS; this was done with the help of a Wave Glider ASV with a communications gateway. The results from these experiments provide a background for assessing potential future UAS operations in a compositional MOAO.

  12. Impacts of changes in climate, land use and land cover on atmospheric mercury

    Science.gov (United States)

    Zhang, H.; Holmes, C. D.; Wu, S.

    2016-09-01

    Mercury is an important pollutant that can be transported globally due to its long lifetime in the atmosphere. Atmosphere-surface exchange is a major process affecting the cycling of mercury in the global environment and its impacts on food webs. We investigate the sensitivities of the air-surface exchange, atmospheric transport, and budget of mercury to projected 2000-2050 changes in climate and land use/land cover with a global chemical transport model (GEOS-Chem). We find that annual mean Hg(0) dry deposition flux over land could increase by up to 20% in northern mid-latitudes by 2050 due to increased vegetation and foliage density. Climate change can significantly affect both the wet deposition and atmospheric chemistry of mercury. In response to the projected climate change, the annual mean wet deposition flux increases over most continental regions and decreases over most of the mid-latitude and tropical oceans. The annual mean mercury wet deposition flux over northern and southern high latitudes increases by 7% and 8% respectively, largely driven by increases in precipitation there. Surface Hg(0) is predicted to increase generally, because high temperatures decrease Hg(0) oxidation by bromine and high moisture increases aqueous Hg(II) photo reduction. The combined effects of projected changes in climate, land use and land cover increase mercury deposition to the continental biosphere and decrease mercury deposition to the marine biosphere.

  13. The impact on atmospheric CO2 of iron fertilization induced changes in the ocean's biological pump

    Directory of Open Access Journals (Sweden)

    J. C. McWilliams

    2007-10-01

    Full Text Available Using numerical simulations, we quantify the impact of changes in the ocean's biological pump on the air-sea balance of CO2 by fertilizing a small surface patch in the high-nutrient, low-chlorophyll region of the eastern tropical Pacific with iron. Decade-long fertilization experiments are conducted in a basin-scale, eddy-permitting coupled physical biogeochemical ecological model. In contrast to previous studies, we find that most of the dissolved inorganic carbon (DIC removed from the euphotic zone by the enhanced biological export is replaced by uptake of CO2 from the atmosphere. Atmospheric uptake efficiencies, the ratio of the perturbation in air-sea CO2 flux to the perturbation in export flux across 100 m, are 0.75 to 0.93 in our patch size-scale experiments. The atmospheric uptake efficiency is insensitive to the duration of the experiment. The primary factor controlling the atmospheric uptake efficiency is the vertical distribution of the enhanced biological production. Iron fertilization at the surface tends to induce production anomalies primarily near the surface, leading to high efficiencies. In contrast, mechanisms that induce deep production anomalies (e.g. altered light availability tend to have a low uptake efficiency, since most of the removed DIC is replaced by lateral and vertical transport and mixing. Despite high atmospheric uptake efficiencies, patch-scale iron fertilization of the ocean's biological pump tends to remove little CO2 from the atmosphere over the decadal timescale considered here.

  14. Atmospheric depression-mediated water temperature changes affect the vertical movement of chum salmon Oncorhynchus keta.

    Science.gov (United States)

    Kitagawa, Takashi; Hyodo, Susumu; Sato, Katsufumi

    2016-08-01

    The Sanriku coastal area, Japan, is one of the southern-most natural spawning regions of chum salmon Oncorhynchus keta. Here, we report their behavioral response to changes in ambient temperature after the passage of an atmospheric depression during the early spawning season. Before the passage, all electrically tagged fish moved vertically for several hours to depths below the shallow thermocline at >100 m. However, during the atmospheric depression, the salmon shortened the duration of their vertical movements and spent most time at the surface. The water column was homogenous at energy cost during migration.

  15. Changes in atmospheric aerosol loading retrieved from space based measurements during the past decade

    Science.gov (United States)

    Yoon, J.; Burrows, J. P.; Vountas, M.; von Hoyningen-Huene, W.; Chang, D. Y.; Richter, A.; Hilboll, A.

    2013-10-01

    Atmospheric aerosol, generated from natural and anthropogenic sources, plays a key role in regulating visibility, air quality, and acid deposition. It is directly linked to and impacts on human health. It also reflects and absorbs incoming solar radiation and thereby influences the climate change. The cooling by aerosols is now recognized to have partly masked the atmospheric warming from fossil fuel combustion emissions. The role and potential management of short-lived climate pollutants such as aerosol are currently a topic of much scientific and public debate. Our limited knowledge of atmospheric aerosol and its influence on the Earth's radiation balance has a significant impact on the accuracy and error of current predictions of the future global climate change. In the past decades, environmental legislation in industrialized countries has begun to limit the release of anthropogenic pollutants. In contrast, in Asia as a result of the recent rapid economic development, emissions from industry and traffic have increased dramatically. In this study, the temporal changes/trends of atmospheric aerosols, derived from the satellite instruments MODIS (on board Terra and Aqua), MISR (Terra), and SeaWiFS (OrbView-2) during the past decade, are investigated. Whilst the aerosol optical thickness, AOT, over Western Europe decreases (i.e. by up to about -40% from 2003 to 2008) and parts of North America, a statistically significant increase (about +34% in the same period) over East China is observed and attributed to both the increase in industrial output and the Asian desert dust.

  16. Effects of atmospheric and climate change at the timberline of the Central European Alps.

    Science.gov (United States)

    Wieser, Gerhard; Matyssek, Rainer; Luzian, Roland; Zwerger, Peter; Pindur, Peter; Oberhuber, Walter; Gruber, Andreas

    2009-06-01

    This review considers potential effects of atmospheric change and climate warming within the timberline ecotone of the Central European Alps. After focusing on the impacts of ozone (O(3)) and rising atmospheric CO(2) concentration, effects of climate warming on the carbon and water balance of timberline trees and forests will be outlined towards conclusions about changes in tree growth and treeline dynamics.Presently, ambient ground-level O(3) concentrations do not exert crucial stress on adult conifers at the timberline of the Central European Alps. In response to elevated atmospheric CO(2)Larix decidua showed growth increase, whereas no such response was found in Pinus uncinata. Overall climate warming appears as the factor responsible for the observed growth stimulation of timberline trees.Increased seedling re-establishment in the Central European Alps however, resulted from invasion into potential habitats rather than upward migration due to climate change, although seedlings will only reach tree size upon successful coupling with the atmosphere and thus loosing the beneficial microclimate of low stature vegetation.In conclusion, future climate extremes are more likely than the gradual temperature increase to control treeline dynamics in the Central European Alps.

  17. Changes in the microbiota of lamb packaged in a vacuum and in modified atmospheres during chilled storage analysed by high-throughput sequencing.

    Science.gov (United States)

    Wang, Taojun; Zhao, Liang; Sun, Yanan; Ren, Fazheng; Chen, Shanbin; Zhang, Hao; Guo, Huiyuan

    2016-11-01

    Changes in the microbiota of lamb were investigated under vacuum packaging (VP) and under 20% CO2/80% N2 (LC), 60% CO2/40% N2 (MC), and 100% CO2 (HC) modified atmosphere packaging (MAP) during chilled storage. Viable counts were monitored, and the total microbial communities were assessed by high-throughput sequencing. The starting community had the highest microbial diversity, after which Lactococcus and Carnobacterium spp. outcompeted during the 28-day storage. The relative abundances of Brochothrix spp. in the LC atmosphere were much higher than those of the other groups on days 7 and 28. The bacterial inhibiting effect of the MAP environments on microbial growth was positively correlated with the CO2 concentration. The HC atmosphere inhibited microbial growth and delayed changes in the microbial community composition, extending the lamb's shelf life by approximately 7days compared with the VP atmosphere. Lamb packaged in the VP atmosphere had a more desirable colour but a higher weight loss than lamb packaged in the MAP atmospheres.

  18. Cassini results on Titan's atmospheric and surface properties changes since the northern equinox

    Science.gov (United States)

    Coustenis, Athena; Drossart, Pierre; Flasar, F. Michael; Achterberg, Richard K.; Rodriguez, Sebastien; Nixon, Conor; Bampasidis, Georgios; Solomonidou, Anezina; Jennings, Donald; Lavvas, Panayiotis

    2016-07-01

    -term variations both in the atmosphere and the surface and the two environments are connected. Deposits from the atmosphere can be found on the ground and the tropospheric processes (clouds, rain) affect the appearance of the surface. Thus, we analyse spectro-imaging data (0.8-5.2 µm) from Cassini/VIMS to study Titan's surface multivariable geological terrain and its interactions with the lower atmosphere. The Cassini's Visual and Infrared Mapping Spectrometer (VIMS) and other instruments have provided a better understanding of the dynamic and complex surface expressions of this Saturnian moon, suggesting exogenic and endogenic processes [3;4;5].We apply a Radiative transfer code to analyse different regions and to monitor their spectral behavior with time [6;7,8]. We have already shown that temporal variations of surface albedo (in chemical composition and/or morphology) exist for some areas, but that their origin may differ from one region to the other. Tui Regio and Sotra Patera for instance change with time becoming darker and brighter respectively in terms of surface albedo while the undifferentiated plains and the suggested evaporitic areas in the equatorial regions do not present any significant change [8]. We will infer information on the haze content that we will compare with findings from the stratosphere by CIRS and we will compare with cloud monitoring over specific regions [9]. It remains to identify the role the atmosphere plays in the surface changes. References: [1] Coustenis, et al., Icarus 207, 461, 2010 ; Astrophys. J. 799, 177, 9p ; Icarus, in press, 2015 ; [2] Jennings et al., ApJ 804, L34, 5, 2015; [3] Lopes, R.M.C., et al.: JGR, 118, 416-435, 2013 ; [4] Solomonidou, A., et al.: PSS, 70, 77-104, 2013 ; [5] Moore, J.M., and Howard, A.D.: GRL, 37, L22205, 2010; [6] Hirtzig, M., et al.: Icarus, 226, 470-486, 2013 ; [7] Solomonidou, A., et al.: JGR, 119, 1729-1747, 2014; [8] Solomonidou, A., et al.: Icarus, in press, 2015; [9] Rodriguez et al., Icarus 216, 89

  19. Lichens as biomonitor of atmospheric aerosol composition in the Northwest European Russia

    Science.gov (United States)

    Shevchenko, Vladimir P.; Pokrovsky, Oleg S.; Zamber, Natalia S.; Konov, Konstantin G.; Starodymova, Dina P.

    2010-05-01

    Numerous studies have shown that aerosols are of importance for atmospheric chemistry and climate of the Arctic. At the coasts of Arctic seas and in their catchment areas delivery of chemical elements and compounds are registered in natural archives, for example in lichens. Lichens absorb substances, including trace elements, through dry and wet deposition, and have been widely used as biomonitors. We studied multi-element composition of terricolous (mostly of genera Cladonia and Cetraria) and fruticose epiphytic (mostly of genera Alectoria, Usnea and Bryoria) lichens collected in 2004-2009 in Kola Peninsula, Karelia, Arkhangelsk Region and Komi Republic of NW Russia, mostly in the frame of International Polar Year activity. About 110 samples were analyzed. The unwashed lichen samples were air dried and homogenised to a fine powder in an agate crusher. Samples were treated in a four-step chemical digestion procedure (full dissolution via acid attack) and element concentrations were determined by inductively coupled plasma-mass spectrometry (ICP-MS). Parts of dry samples were analyzed by instrumental neutron activation analysis (INAA). An enrichment factor (EF) was calculated for each element (X) relative to the composition of earth's crust: EF = ((X/Al) in lichen) / ((X/Al) in the earth's crust). Al was used as a crustal indicator. In most samples contents of Ti, V, Cr, Mn, Fe, Co, rare earth elements (REEs), Th, U are at the background level and their EFs are less than 10. These low EF values indicated that, relative to average values for crustal rocks, there was no enrichment of these elements in the lichen concerned. For some elements (Se, Cd, Zn, Sb, Pb, As, Ni, Cu) consistently higher EF values were obtained. These higher values were interpreted in terms of sources of both anthropogenic and natural sources other than crustal rock and (or) soil. These elements could be derived by long-range atmospheric transport. Highest concentrations of Cu, Ni, Pb in lichens

  20. Long-term increase in snow depth leads to compositional changes in arctic ectomycorrhizal fungal communities.

    Science.gov (United States)

    Morgado, Luis N; Semenova, Tatiana A; Welker, Jeffrey M; Walker, Marilyn D; Smets, Erik; Geml, József

    2016-09-01

    Many arctic ecological processes are regulated by soil temperature that is tightly interconnected with snow cover distribution and persistence. Recently, various climate-induced changes have been observed in arctic tundra ecosystems, e.g. shrub expansion, resulting in reduction in albedo and greater C fixation in aboveground vegetation as well as increased rates of soil C mobilization by microbes. Importantly, the net effects of these shifts are unknown, in part because our understanding of belowground processes is limited. Here, we focus on the effects of increased snow depth, and as a consequence, increased winter soil temperature on ectomycorrhizal (ECM) fungal communities in dry and moist tundra. We analyzed deep DNA sequence data from soil samples taken at a long-term snow fence experiment in Northern Alaska. Our results indicate that, in contrast with previously observed responses of plants to increased snow depth at the same experimental site, the ECM fungal community of the dry tundra was more affected by deeper snow than the moist tundra community. In the dry tundra, both community richness and composition were significantly altered while in the moist tundra, only community composition changed significantly while richness did not. We observed a decrease in richness of Tomentella, Inocybe and other taxa adapted to scavenge the soil for labile N forms. On the other hand, richness of Cortinarius, and species with the ability to scavenge the soil for recalcitrant N forms, did not change. We further link ECM fungal traits with C soil pools. If future warmer atmospheric conditions lead to greater winter snow fall, changes in the ECM fungal community will likely influence C emissions and C fixation through altering N plant availability, fungal biomass and soil-plant C-N dynamics, ultimately determining important future interactions between the tundra biosphere and atmosphere.

  1. Variations in atmospheric concentrations and isotopic compositions of gaseous and particulate boron in Shizuoka City, Japan

    Science.gov (United States)

    Sakata, Masahiro; Phan, Hang Giang; Mitsunobu, Satoshi

    2017-01-01

    To clarify the partitioning and isotopic fractionation of boron (B) into the gas and particle phases in the atmosphere, the concentrations and isotopic compositions of gaseous and particulate B were measured concurrently for more than one year at a site in Shizuoka City, Japan. This area has few anthropogenic sources of B, such as coal combustion facilities. Gaseous B concentration showed clearly a seasonal variation, increasing during summer and decreasing during winter. Conversely, particulate B concentration tended to decrease during the warm season and increase during winter. The increase in gaseous B concentration during summer is attributable to the enhanced emissions of B from sea-salt degassing owing to higher temperatures and the predominance of winds from the Pacific Ocean. Moreover, the decrease in gaseous B concentration and the increase in particulate B concentration during winter is probably due to the enhanced condensation of gaseous B on atmospheric particles. The δ11B values of gaseous and particulate B varied largely, and did not indicate a distinctive seasonal variation. A positive correlation was observed between the δ11B values of gaseous and particulate B (R2 = 0.518, P < 0.001). Moreover, the δ11B values of particulate B were approximately 0-20‰ lower than those of gaseous B. There is an isotopic fractionation (ΔB(OH)4- -B(OH)3) of about -20‰ between B(OH)3 and B(OH)4- species in solution (Kakihana et al., 1977). This tends to support the hypotheses that gaseous B is transformed to particulate B through the reaction of condensed B(OH)3 with chemical constituents on particles to precipitate borates, and that the condensed B(OH)3 remaining on particles is unstable and evaporates.

  2. Compositional waves and variations in the atmospheric abundances of magnetic stars

    CERN Document Server

    Urpin, Vadim

    2016-01-01

    The stars of the middle main sequence often have relatively quiescent outer layers and spot-like chemical structures may develope in their atmospheres. Recent observations show that abundance peculiarities can change as stars evolve on the main sequence and the timescale of these changes lies in a wide range from million years to months. These observations imply that, perhaps, our understanding of diffusion processes at work in magnetic stars is incomplete and a more detailed analysis of these processes is required. In the present paper, we consider diffusion caused by a combined influence of the electric current and the Hall effect.Such diffusion has a number of very particular properties and, generally, can change the surface chemistry of stars in combination with other diffusion processes. For instance, current-driven diffusion is accompanied by a propagation of the special type of waves in which only the impurity number density oscillates. Propagation of such waves changes the shape and size of spots as w...

  3. Changing atmospheric CO2 concentration was the primary driver of early Cenozoic climate.

    Science.gov (United States)

    Anagnostou, Eleni; John, Eleanor H; Edgar, Kirsty M; Foster, Gavin L; Ridgwell, Andy; Inglis, Gordon N; Pancost, Richard D; Lunt, Daniel J; Pearson, Paul N

    2016-05-19

    The Early Eocene Climate Optimum (EECO, which occurred about 51 to 53 million years ago), was the warmest interval of the past 65 million years, with mean annual surface air temperature over ten degrees Celsius warmer than during the pre-industrial period. Subsequent global cooling in the middle and late Eocene epoch, especially at high latitudes, eventually led to continental ice sheet development in Antarctica in the early Oligocene epoch (about 33.6 million years ago). However, existing estimates place atmospheric carbon dioxide (CO2) levels during the Eocene at 500-3,000 parts per million, and in the absence of tighter constraints carbon-climate interactions over this interval remain uncertain. Here we use recent analytical and methodological developments to generate a new high-fidelity record of CO2 concentrations using the boron isotope (δ(11)B) composition of well preserved planktonic foraminifera from the Tanzania Drilling Project, revising previous estimates. Although species-level uncertainties make absolute values difficult to constrain, CO2 concentrations during the EECO were around 1,400 parts per million. The relative decline in CO2 concentration through the Eocene is more robustly constrained at about fifty per cent, with a further decline into the Oligocene. Provided the latitudinal dependency of sea surface temperature change for a given climate forcing in the Eocene was similar to that of the late Quaternary period, this CO2 decline was sufficient to drive the well documented high- and low-latitude cooling that occurred through the Eocene. Once the change in global temperature between the pre-industrial period and the Eocene caused by the action of all known slow feedbacks (apart from those associated with the carbon cycle) is removed, both the EECO and the late Eocene exhibit an equilibrium climate sensitivity relative to the pre-industrial period of 2.1 to 4.6 degrees Celsius per CO2 doubling (66 per cent confidence), which is similar to the

  4. Changing atmospheric CO2 concentration was the primary driver of early Cenozoic climate

    Science.gov (United States)

    Anagnostou, Eleni; John, Eleanor H.; Edgar, Kirsty M.; Foster, Gavin L.; Ridgwell, Andy; Inglis, Gordon N.; Pancost, Richard D.; Lunt, Daniel J.; Pearson, Paul N.

    2016-05-01

    The Early Eocene Climate Optimum (EECO, which occurred about 51 to 53 million years ago), was the warmest interval of the past 65 million years, with mean annual surface air temperature over ten degrees Celsius warmer than during the pre-industrial period. Subsequent global cooling in the middle and late Eocene epoch, especially at high latitudes, eventually led to continental ice sheet development in Antarctica in the early Oligocene epoch (about 33.6 million years ago). However, existing estimates place atmospheric carbon dioxide (CO2) levels during the Eocene at 500-3,000 parts per million, and in the absence of tighter constraints carbon-climate interactions over this interval remain uncertain. Here we use recent analytical and methodological developments to generate a new high-fidelity record of CO2 concentrations using the boron isotope (δ11B) composition of well preserved planktonic foraminifera from the Tanzania Drilling Project, revising previous estimates. Although species-level uncertainties make absolute values difficult to constrain, CO2 concentrations during the EECO were around 1,400 parts per million. The relative decline in CO2 concentration through the Eocene is more robustly constrained at about fifty per cent, with a further decline into the Oligocene. Provided the latitudinal dependency of sea surface temperature change for a given climate forcing in the Eocene was similar to that of the late Quaternary period, this CO2 decline was sufficient to drive the well documented high- and low-latitude cooling that occurred through the Eocene. Once the change in global temperature between the pre-industrial period and the Eocene caused by the action of all known slow feedbacks (apart from those associated with the carbon cycle) is removed, both the EECO and the late Eocene exhibit an equilibrium climate sensitivity relative to the pre-industrial period of 2.1 to 4.6 degrees Celsius per CO2 doubling (66 per cent confidence), which is similar to the

  5. The MACC reanalysis: an 8-yr data set of atmospheric composition

    Directory of Open Access Journals (Sweden)

    A. Inness

    2012-12-01

    Full Text Available An eight-year long reanalysis of atmospheric composition data covering the period 2003–2010 was constructed as part of the FP7 funded Monitoring Atmospheric Composition and Climate project by assimilating satellite data into a global model and data assimilation system. This reanalysis provides fields of chemically reactive gases, namely carbon monoxide, ozone, nitrogen oxides, and formaldehyde, as well as aerosols and greenhouse gases globally at a resolution of about 80 km for both the troposphere and the stratosphere. This paper describes the assimilation system for the reactive gases and presents validation results for the reactive gases analysis fields to document the dataset and to give a first indication of its quality.

    Tropospheric CO values from the MACC reanalysis are on average 10–20% lower than routine observations from commercial aircrafts over airports through most of the troposphere, and have larger negative biases in the boundary layer at urban sites affected by air pollution, possibly due to an underestimation of CO or precursor emissions.

    Stratospheric ozone fields from the MACC reanalysis agree with ozone sondes and ACE-FTS data to within ±10% in most situations. In the troposphere the reanalysis shows biases of −5% to +10% with respect to ozone sondes and aircraft data in the extratropics, but has larger negative biases in the tropics. Area averaged total column ozone agrees with ozone fields from a multi sensor reanalysis data set to within a few percent.

    NO2 fields from the reanalysis show the right seasonality over polluted urban areas of the NH and over tropical biomass burning areas, but underestimate wintertime NO2 maxima over anthropogenic pollution regions and overestimate NO2 in Northern and Southern Africa during the tropical biomass burning seasons.

    Tropospheric HCHO is well simulated in the MACC reanalysis even though no satellite data are

  6. The MACC reanalysis: an 8 yr data set of atmospheric composition

    Directory of Open Access Journals (Sweden)

    A. Inness

    2013-04-01

    Full Text Available An eight-year long reanalysis of atmospheric composition data covering the period 2003–2010 was constructed as part of the FP7-funded Monitoring Atmospheric Composition and Climate project by assimilating satellite data into a global model and data assimilation system. This reanalysis provides fields of chemically reactive gases, namely carbon monoxide, ozone, nitrogen oxides, and formaldehyde, as well as aerosols and greenhouse gases globally at a horizontal resolution of about 80 km for both the troposphere and the stratosphere. This paper describes the assimilation system for the reactive gases and presents validation results for the reactive gas analysis fields to document the data set and to give a first indication of its quality. Tropospheric CO values from the MACC reanalysis are on average 10–20% lower than routine observations from commercial aircrafts over airports through most of the troposphere, and have larger negative biases in the boundary layer at urban sites affected by air pollution, possibly due to an underestimation of CO or precursor emissions. Stratospheric ozone fields from the MACC reanalysis agree with ozonesondes and ACE-FTS data to within ±10% in most seasons and regions. In the troposphere the reanalysis shows biases of −5% to +10% with respect to ozonesondes and aircraft data in the extratropics, but has larger negative biases in the tropics. Area-averaged total column ozone agrees with ozone fields from a multi-sensor reanalysis data set to within a few percent. NO2 fields from the reanalysis show the right seasonality over polluted urban areas of the NH and over tropical biomass burning areas, but underestimate wintertime NO2 maxima over anthropogenic pollution regions and overestimate NO2 in northern and southern Africa during the tropical biomass burning seasons. Tropospheric HCHO is well simulated in the MACC reanalysis even though no satellite data are assimilated. It shows good agreement with

  7. Projected land photosynthesis constrained by changes in the seasonal cycle of atmospheric CO2

    Science.gov (United States)

    Wenzel, Sabrina; Cox, Peter M.; Eyring, Veronika; Friedlingstein, Pierre

    2016-10-01

    Uncertainties in the response of vegetation to rising atmospheric CO2 concentrations contribute to the large spread in projections of future climate change. Climate-carbon cycle models generally agree that elevated atmospheric CO2 concentrations will enhance terrestrial gross primary productivity (GPP). However, the magnitude of this CO2 fertilization effect varies from a 20 per cent to a 60 per cent increase in GPP for a doubling of atmospheric CO2 concentrations in model studies. Here we demonstrate emergent constraints on large-scale CO2 fertilization using observed changes in the amplitude of the atmospheric CO2 seasonal cycle that are thought to be the result of increasing terrestrial GPP. Our comparison of atmospheric CO2 measurements from Point Barrow in Alaska and Cape Kumukahi in Hawaii with historical simulations of the latest climate-carbon cycle models demonstrates that the increase in the amplitude of the CO2 seasonal cycle at both measurement sites is consistent with increasing annual mean GPP, driven in part by climate warming, but with differences in CO2 fertilization controlling the spread among the model trends. As a result, the relationship between the amplitude of the CO2 seasonal cycle and the magnitude of CO2 fertilization of GPP is almost linear across the entire ensemble of models. When combined with the observed trends in the seasonal CO2 amplitude, these relationships lead to consistent emergent constraints on the CO2 fertilization of GPP. Overall, we estimate a GPP increase of 37 ± 9 per cent for high-latitude ecosystems and 32 ± 9 per cent for extratropical ecosystems under a doubling of atmospheric CO2 concentrations on the basis of the Point Barrow and Cape Kumukahi records, respectively.

  8. Silica-based composite and mixed-oxide nanoparticles from atmospheric pressure flame synthesis

    Science.gov (United States)

    Akurati, Kranthi K.; Dittmann, Rainer; Vital, Andri; Klotz, Ulrich; Hug, Paul; Graule, Thomas; Winterer, Markus

    2006-08-01

    Binary TiO2/SiO2 and SnO2/SiO2 nanoparticles have been synthesized by feeding evaporated precursor mixtures into an atmospheric pressure diffusion flame. Particles with controlled Si:Ti and Si:Sn ratios were produced at various flow rates of oxygen and the resulting powders were characterized by BET (Brunauer-Emmett-Teller) surface area analysis, XRD, TEM and Raman spectroscopy. In the Si-O-Ti system, mixed oxide composite particles exhibiting anatase segregation formed when the Si:Ti ratio exceeded 9.8:1, while at lower concentrations only mixed oxide single phase particles were found. Arrangement of the species and phases within the particles correspond to an intermediate equilibrium state at elevated temperature. This can be explained by rapid quenching of the particles in the flame and is in accordance with liquid phase solubility data of Ti in SiO2. In contrast, only composite particles formed in the Sn-O-Si system, with SnO2 nanoparticles predominantly found adhering to the surface of SiO2 substrate nanoparticles. Differences in the arrangement of phases and constituents within the particles were observed at constant precursor mixture concentration and the size of the resultant segregated phase was influenced by varying the flow rate of the oxidant. The above effect is due to the variation of the residence time and quenching rate experienced by the binary oxide nanoparticles when varying the oxygen flow rate and shows the flexibility of diffusion flame aerosol reactors.

  9. Changes in atmospheric circulation between solar maximum and minimum conditions in winter and summer

    Science.gov (United States)

    Lee, Jae Nyung

    2008-10-01

    Statistically significant climate responses to the solar variability are found in Northern Annular Mode (NAM) and in the tropical circulation. This study is based on the statistical analysis of numerical simulations with ModelE version of the chemistry coupled Goddard Institute for Space Studies (GISS) general circulation model (GCM) and National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis. The low frequency large scale variability of the winter and summer circulation is described by the NAM, the leading Empirical Orthogonal Function (EOF) of geopotential heights. The newly defined seasonal annular modes and its dynamical significance in the stratosphere and troposphere in the GISS ModelE is shown and compared with those in the NCEP/NCAR reanalysis. In the stratosphere, the summer NAM obtained from NCEP/NCAR reanalysis as well as from the ModelE simulations has the same sign throughout the northern hemisphere, but shows greater variability at low latitudes. The patterns in both analyses are consistent with the interpretation that low NAM conditions represent an enhancement of the seasonal difference between the summer and the annual averages of geopotential height, temperature and velocity distributions, while the reverse holds for high NAM conditions. Composite analysis of high and low NAM cases in both the model and observation suggests that the summer stratosphere is more "summer-like" when the solar activity is near a maximum. This means that the zonal easterly wind flow is stronger and the temperature is higher than normal. Thus increased irradiance favors a low summer NAM. A quantitative comparison of the anti-correlation between the NAM and the solar forcing is presented in the model and in the observation, both of which show lower/higher NAM index in solar maximum/minimum conditions. The summer NAM in the troposphere obtained from NCEP/NCAR reanalysis has a dipolar zonal structure with maximum

  10. Photoinduced refractive index change and absorption bleaching in poly(methylphenylsilane) under varied atmospheres.

    Energy Technology Data Exchange (ETDEWEB)

    Potter, Barrett George, Jr. (University of Arizona, Tucson, AZ); Simmons-Potter, Kelly (University of Arizona, Tucson, AZ); Chandra, Haripin (University of Arizona, Tucson, AZ); Thomes, William Joseph, Jr.; Jamison, Gregory Marks

    2005-06-01

    Polysilane materials exhibit large photo-induced refractive index changes under low incident optical fluences, making them attractive candidates for applications in which rapid patterning of photonic device structures is desired immediately prior to their use. This agile fabrication strategy for integrated photonics inherently requires that optical exposure, and associated material response, occurs in nonlaboratory environments, motivating the study of environmental conditions on the photoinduced response of the material. The present work examines the impact of atmosphere on the photosensitive response of poly(methylphenylsilane) (PMPS) thin films in terms of both photoinduced absorption change and refractive index modification. Material was subjected to UV light exposure resonant with the lowest energy optical transition associated with the conjugated Si-Si backbone. Exposures were performed in both aerobic and anaerobic atmospheres (oxygen, air, nitrogen, and 5% H{sub 2}/95% N{sub 2}). The results clearly demonstrate that the photosensitive response of this model polysilane material was dramatically affected by local environment, exhibiting a photoinduced refractive index change, when exposed under an oxygen containing atmosphere, that was twice that observed under anaerobic conditions. This effect is discussed in terms of photo-oxidation processes within the polysilane structure and in the context of the need for predictable photosensitive refractive index change in varied photoimprinting environments.

  11. Trends in the composition of wet deposition: effects of the atmospheric rehabilitation in East-Germany

    Science.gov (United States)

    Marquardt, Wolfgang; Brüggemann, Erika; Ihle, Peter

    1996-07-01

    The chemical components in precipitation largely depend on type and quantity of emissions on the course of the air masses at the sampling site. Beginning in 1982, the concentrations of major ions in precipitation at initially 3 sites are described in total as well as arrival sectors. For regions with specific geographical or emission features, 5 to 7 sectors for every sampling site are established, e.g., Scandinavia, or the centres of brown coal combustion in the former GDR. Particulary from the sectors of the former GDR, the precipitation was over-averaged contaminated anthropogenically in the years before the political change. Some components were significantly raised in comparison to other sectors. However, acidity remained on the level of the other sectors in the 80s. In the early 90s, anthropogenic emissions were systematically reduced partly by substitution of brown coal of inferior quality, better flue gas cleaning and partly by closing down industries. The effect of such steps on the wet deposition is being studied in a national German SANA research project (SANA: scientific program of rehabilitation of the atmosphere). In this project, the sampling sites were extended to 7 while maintaining the sampling procedure and the recording of relevant meteorological input-data. As a result, there now exists a homogeneous long-term data base allowing us to study the effects of emissions on wet deposition by the rehabilitation of the atmosphere in the former GDR. The paper focusses on changes in sulphate, nitrate, calcium, acidity, chloride and potassium concentrations in precipitation at the 3 so-called long-term sites. There are conspicuous decreases of some ions on one hand, but there is also an increase of nitrate and acidity, especially in recent years.

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

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ying [College of Material and Textile Engineering, Jiaxing University, Jiaxing 314033 (China); Center for Plasma-Aided Manufacturing, Madison, WI 53706 (United States); School of Human Ecology, University of Wisconsin-Madison, Madison, WI 53706 (United States); Manolache, Sorin [Center for Plasma-Aided Manufacturing, Madison, WI 53706 (United States); US Forest Products Laboratory, Madison, WI 53726 (United States); Qiu, Yiping, E-mail: ypqiu@dhu.edu.cn [College of Textiles, Donghua University, Shanghai 201620 (China); Sarmadi, Majid, E-mail: majidsar@wisc.edu [Center for Plasma-Aided Manufacturing, Madison, WI 53706 (United States); School of Human Ecology, University of Wisconsin-Madison, Madison, WI 53706 (United States); Materials Science Program, University of Wisconsin-Madison, Madison, WI 53706 (United States)

    2016-02-28

    Graphical abstract: - Highlights: • The continuous ethanol flow technique can successfully modify ramie fiber surface with an increase in IFSS value up to 50%. • Response surface methodology was applied to design the plasma treatment parameters for ramie fiber modification. • The ethanol flow rate was the most influential treatment parameter in plasma modification process. - Abstract: In order to improve the interfacial adhesion between hydrophilic ramie fibers and hydrophobic polypropylene (PP) matrices, ramie fibers are modified by atmospheric pressure dielectric barrier discharge (DBD) plasma with our continuous ethanol flow technique in helium environment. A central composite design of experiments with different plasma processing parameter combinations (treatment current, treatment time and ethanol flow rate) is applied to find the most influential parameter and to obtain the best modification effect. Field emission scanning electron microscope (SEM) shows the roughened surfaces of ramie fibers from the treated groups due to plasma etching effect. Dynamic contact angle analysis (DCAA) demonstrates that the wettability of the treated fibers drastically decreases. Microbond pullout test shows that the interfacial shear strength (IFSS) between treated ramie fibers and PP matrices increases significantly. Residual gas analysis (RGA) confirms the creation of ethyl groups during plasma treatment. This study shows that our continuous ethanol flow technique is effective in the plasma modification process, during which the ethanol flow rate is the most influential parameter but all parameters have simultaneous influence on plasma modification effect of ramie fibers.

  13. Design of atmospheric composition monitor based on ultraviolet optical absorption technology

    Institute of Scientific and Technical Information of China (English)

    LI Wen-jun

    2011-01-01

    An open path atmospheric composition monitor is designed based on ultraviolet differential absorption technology.Dark current correction and diode response correction are used to improve the detection limit and Savitzky-Golay filter is used to improve the measurement accuracy.The experimental results show that the designed system has the ability to measure NO and NO2 in real time with reasonable accuracy.The detection limit of the system is about 0.25 ppm for NO and 0.28 ppm for NOr When the concentration level of the target gases is below 100 ppm,the system has good linearity and high measurement accuracy,i.e.,the measurement accuracy is about 2% for NO and about 4% for NO2.The detection limit of dark current can be improved by about 5 to 10 ppb,and the correction of diode response can improve the detection limit by around 30 ppb.Moving window average can improve the detection limit at low concentration levels but will generate more errors at higher concentration leveis.Generally,the designed system meets the requirement of measuring multi-species air pollutants in real time and accurately.

  14. Atmospheric pressure cold plasma treatment of cellulose based fillers for wood plastic composites

    Science.gov (United States)

    Lekobou, William; Englund, Karl; Pedrow, Patrick; Scudiero, Louis

    2011-10-01

    The main challenge of wood plastic composites (WPC) resides in the low interfacial adhesion due to incompatibility between the cellulose based filler that has a polar surface and most common matrixes, polyolefins which are non-polar. Plasma treatment is a promising technique for surface modification and its implementation into the processing of WPC would provide this industry with a versatile and nearly environmentally benign manufacturing tool. Our investigation aims at designing a cold atmospheric pressure plasma reactor for coating fillers with a hydrophobic material prior to compounding with the matrix. Deposition was achieved with our reactor that includes an array of high voltage needles, a grounded metal mesh, Ar as carrier gas and C2H2 as the precursor molecule. Parameters studied have included gas feed rates and applied voltage; FTIR, ESCA, AFM and SEM imaging were used for film diagnostics. We will also report on deposition rate and its dependence on radial and axial position as well as the effects of plasma-polymerized acetylene on the surface free energy of cellulose based substrates.

  15. Changes in the milk composition of nonpuerperal women.

    Science.gov (United States)

    Kulski, J K; Hartmann, P E; Saint, W J; Giles, P F; Gutteridge, D H

    1981-03-01

    Studies were undertaken to determine the effect of expressing small volumes of breast fluid (less than 3.0 ml) on the progressive changes in concentrations of lactose, proteins, and electrolytes in the mammary secretions of four nonpuerperal women with galactorrhea and two nonpuerperal women who artificially induced lactation by breast hyperstimulation. The changes in the concentration of the milk constituents in the mammary secretion of these women are compared to the levels in colostrum, transitional and mature milk obtained from normal lactationg women. In one woman galactorrhea was associated with hypothyroidism and abnormally elevated blood levels of prolactin and thyroid-stimulating hormone. The breast secretion contained lactose, protein, and alpha-lactalbumin at colostrum-like levels over the entire 53 days of sampling. In two women with galactorrhea and amenorrhea associated with a pituitary tumor and hyperprolactinemia, a colostrum-like secretion was expressed on the first day of sampling but with daily sampling during a period of a month the composition approached that of normal milk. Similar results were obtained in another woman with galactorrhea, which appeared to be induced by a psychotropic drug (haloperidol), when she expressed breast fluid at 2-day intervals over a period of a month. In a second series of samples collected from this woman at intervals of 5 days or more over a period of a month, the concentration of lactose and proteins remained at colostrum levels. The composition of the breast secretion produced by two women who induced lactation artificially by breast hyperstimulation was close to the composition obtained for women during established lactation following normal pregnancy. These findings are discussed in relation to breast function and endocrine disorders.

  16. Impacts of aerosol-cloud interactions on past and future changes in tropospheric composition

    Energy Technology Data Exchange (ETDEWEB)

    Unger, N.; Menon, S.; Shindell, D. T.; Koch, D. M.

    2009-02-02

    The development of effective emissions control policies that are beneficial to both climate and air quality requires a detailed understanding of all the feedbacks in the atmospheric composition and climate system. We perform sensitivity studies with a global atmospheric composition-climate model to assess the impact of aerosols on tropospheric chemistry through their modification on clouds, aerosol-cloud interactions (ACI). The model includes coupling between both tropospheric gas-phase and aerosol chemistry and aerosols and liquid-phase clouds. We investigate past impacts from preindustrial (PI) to present day (PD) and future impacts from PD to 2050 (for the moderate IPCC A1B scenario) that embrace a wide spectrum of precursor emission changes and consequential ACI. The aerosol indirect effect (AIE) is estimated to be -2.0 Wm{sup -2} for PD-PI and -0.6 Wm{sup -2} for 2050-PD, at the high end of current estimates. Inclusion of ACI substantially impacts changes in global mean methane lifetime across both time periods, enhancing the past and future increases by 10% and 30%, respectively. In regions where pollution emissions increase, inclusion of ACI leads to 20% enhancements in in-cloud sulfate production and {approx}10% enhancements in sulfate wet deposition that is displaced away from the immediate source regions. The enhanced in-cloud sulfate formation leads to larger increases in surface sulfate across polluted regions ({approx}10-30%). Nitric acid wet deposition is dampened by 15-20% across the industrialized regions due to ACI allowing additional re-release of reactive nitrogen that contributes to 1-2 ppbv increases in surface ozone in outflow regions. Our model findings indicate that ACI must be considered in studies of methane trends and projections of future changes to particulate matter air quality.

  17. A Revival of Waste: Atmospheric Pressure Nitrogen Plasma Jet Enhanced Jumbo Silicon/Silicon Carbide Composite in Lithium Ion Batteries.

    Science.gov (United States)

    Chen, Bing-Hong; Chuang, Shang-I; Liu, Wei-Ren; Duh, Jenq-Gong

    2015-12-30

    In this study, a jumbo silicon/silicon carbide (Si/SiC) composite (JSC), a novel anode material source, was extracted from solar power industry cutting waste and used as a material for lithium-ion batteries (LIBs), instead of manufacturing the nanolized-Si. Unlike previous methods used for preventing volume expansion and solid electrolyte interphase (SEI), the approach proposed here simply entails applying surface modification to JSC-based electrodes by using nitrogen-atmospheric pressure plasma jet (N-APPJ) treatment process. Surface organic bonds were rearranged and N-doped compounds were formed on the electrodes through applying different plasma treatment durations, and the qualitative examinations of before/after plasma treatment were identified by X-ray photoelectron spectroscopy (XPS) and electron probe microanalyzer (EPMA). The surface modification resulted in the enhancement of electrochemical performance with stable capacity retention and high Coulombic efficiency. In addition, depth profile and scanning electron microscope (SEM) images were executed to determine the existence of Li-N matrix and how the nitrogen compounds change the surface conditions of the electrodes. The N-APPJ-induced rapid surface modification is a major breakthrough for processing recycled waste that can serve as anode materials for next-generation high-performance LIBs.

  18. Rare earths and trace elements contents in leaves: A new indicator of the composition of atmospheric dust.

    Science.gov (United States)

    Censi, P; Cibella, F; Falcone, E E; Cuttitta, G; Saiano, F; Inguaggiato, C; Latteo, V

    2017-02-01

    The relationship between the trace element distribution in atmospheric particles and leaves of some exposed plants in the environment was recently demonstrated. This indication would suggest that the trace element analysis of leaves in these plants could provide information about the composition, nature and origin of the atmospheric dust dispersed in the environment. In order to corroborate this hypothesis, the distribution of trace elements and Rare Earths were studied in leaves of some endemic plants, in the atmospheric fallout and in soils of rural, urban and industrial ecosystems in Sicily. These elements have been chosen to discriminate the source and nature of different source on atmospheric dust and the larger capability of the composition of the latter materials to influence the metal ion distribution in leaves of studied plants rather than the soil composition. These evidences are related to the recognition both of positive La anomaly and trace element enrichments in studied leaves and to their particular V/Th and Co/Ni signature. On the other hand, some particular normalised REE features recognised in leaves suggest that a limited contribution to the REE budget in studied leaves is provided by the REE migration from roots.

  19. Remote Sensing of lower thermospheric temperature and composition based on observations of O2 Atmospheric band emission.

    Science.gov (United States)

    Christensen, A. B.; Yee, J.; Budzien, S. A.; Bishop, R. L.; Hecht, J. H.; Stephan, A. W.; Crowley, G.

    2011-12-01

    The properties of the O2 Atmospheric bands emitted in the lower thermosphere are examined through the use of a photochemical model and compared with measurements from the RAIDS near-infrared spectrometer on the International Space Station. An updated model (Yee, 2011) has been used to establish the sensitivity of the line-of-sight (LOS) brightness of the (0,0), (1,1) and (0,1) bands to changes in neutral composition and some reaction rate and branching ratios. We found that the most sensitive region to O2 variability is near 120 km where the brightness is ~ [O2]^2. Calculations based on the MSIS-90E neutral atmospheric model corresponding to the geographical locations of the brightness measurements at 120 and 125 km for several days of observations indicate greater variability in the model results than observed by RAIDS based on our current understanding of the pointing errors. Up to about 200 km the (0,0) band lifetime is sufficiently long to allow thermalization of the upper state through collisions with the background gasses making the rotational distribution representative of the local temperature. The analysis of rocket data by Heller et al. (1991) and more recently Sheese et al. (2010) using OSIRIS observations up to an altitude of ~ 110 km illustrates the approach. Using the same measurement concept, the RAIDS data extend the range of altitudes an additional two scale heights to approximately 130 km. Comparing RAIDS and TIMED/SABER LOS measurements we have been able to validate temperatures in the region around 100 km. During moderate geomagnetic activity (Kp ~ 4) localized but greatly enhanced temperatures have been observed. J. W. Heller, A. B. Christensen, J. H. Yee and W. E. Sharp, Mesospheric temperature inferred from daytime observation of the O2 atmospheric (0,0) band system, J. Geophys. Res., 96,19,499-19,505,1991. P. E. Sheese, E. J. Llewellyn, R. L. Gattinger, A. E. Bourassa, D. A. Degenstein, N. D. Lloyd, and I. C. McDade, Temperatures in the

  20. The impact on atmospheric CO2 of iron fertilization induced changes in the ocean's biological pump

    Directory of Open Access Journals (Sweden)

    J. C. McWilliams

    2008-03-01

    Full Text Available Using numerical simulations, we quantify the impact of changes in the ocean's biological pump on the air-sea balance of CO2 by fertilizing a small surface patch in the high-nutrient, low-chlorophyll region of the eastern tropical Pacific with iron. Decade-long fertilization experiments are conducted in a basin-scale, eddy-permitting coupled physical/biogeochemical/ecological model. In contrast to previous studies, we find that most of the dissolved inorganic carbon (DIC removed from the euphotic zone by the enhanced biological export is replaced by uptake of CO2 from the atmosphere. Atmospheric uptake efficiencies, the ratio of the perturbation in air-sea CO2 flux to the perturbation in export flux across 100 m, integrated over 10 years, are 0.75 to 0.93 in our patch size-scale experiments. The atmospheric uptake efficiency is insensitive to the duration of the experiment. The primary factor controlling the atmospheric uptake efficiency is the vertical distribution of the enhanced biological production and export. Iron fertilization at the surface tends to induce production anomalies primarily near the surface, leading to high efficiencies. In contrast, mechanisms that induce deep production anomalies (e.g. altered light availability tend to have a low uptake efficiency, since most of the removed DIC is replaced by lateral and vertical transport and mixing. Despite high atmospheric uptake efficiencies, patch-scale iron fertilization of the ocean's biological pump tends to remove little CO2 from the atmosphere over the decadal timescale considered here.

  1. Nitrogen isotopes in ice core nitrate linked to anthropogenic atmospheric acidity change

    Science.gov (United States)

    Geng, Lei; Alexander, Becky; Cole-Dai, Jihong; Steig, Eric J.; Savarino, Joël; Sofen, Eric D.; Schauer, Andrew J.

    2014-01-01

    Nitrogen stable isotope ratio (δ15N) in Greenland snow nitrate and in North American remote lake sediments has decreased gradually beginning as early as ∼1850 Christian Era. This decrease was attributed to increasing atmospheric deposition of anthropogenic nitrate, reflecting an anthropogenic impact on the global nitrogen cycle, and the impact was thought to be amplified ∼1970. However, our subannually resolved ice core records of δ15N and major ions (e.g., , ) over the last ∼200 y show that the decrease in δ15N is not always associated with increasing concentrations, and the decreasing trend actually leveled off ∼1970. Correlation of δ15N with H+, , and HNO3 concentrations, combined with nitrogen isotope fractionation models, suggests that the δ15N decrease from ∼1850–1970 was mainly caused by an anthropogenic-driven increase in atmospheric acidity through alteration of the gas−particle partitioning of atmospheric nitrate. The concentrations of and also leveled off ∼1970, reflecting the effect of air pollution mitigation strategies in North America on anthropogenic NOx and SO2 emissions. The consequent atmospheric acidity change, as reflected in the ice core record of H+ concentrations, is likely responsible for the leveling off of δ15N ∼1970, which, together with the leveling off of concentrations, suggests a regional mitigation of anthropogenic impact on the nitrogen cycle. Our results highlight the importance of atmospheric processes in controlling δ15N of nitrate and should be considered when using δ15N as a source indicator to study atmospheric flux of nitrate to land surface/ecosystems. PMID:24711383

  2. Changes of quality of Pleurotus ssp. carpophores in modified atmosphere packaging

    Directory of Open Access Journals (Sweden)

    Maria Sapata

    2009-03-01

    Full Text Available There is a general trend towards a continuous increase in fresh market sales of mushrooms and many methods have been researched to improve quality and shelf life during storage and marketing. As it is known, mushrooms are a very perishable commodity, with very high respiration rate and rapid quality deterioration, when kept at ambient temperature. In order to study the effect of modified atmosphere packaging (MAP on the quality of three species of oyster mushrooms, P. ostreatus, P. sajor-caju and P. eryngii, whole mushrooms were packaged with two polymeric low density polyethylene films – Vileda Freshmate (A and PE 52 LV Amcor (B, with passive modified atmosphere and stored at 4ºC. The quality and stability of MA packaged mushrooms were assessed, during storage, by package atmosphere composition (O2, CO2, soluble solid contents, weight loss, texture, surface colour and exudates measurements. It was verified that on the seventh day the P. ostreatus and P. sajor-caju carpophores presented identical quality, when packaged with the two films types, thereafter some decay was observed. Carpophores of P. eryngii had the same quality in the two film types at the end of the established storage.

  3. African land degradation in a world of global atmospheric change: fertilization conceals degradation?

    Science.gov (United States)

    Le, Lulseged Tamene, Paul L. G. Vlek, Quang Bao

    2009-04-01

    Land degradation is one of the most widespread environmental problems worldwide. The sub-Saharan Africa (SSA) is one of the most seriously affected regions with huge implications on food security and economic development. To plan plausible management measures, understanding the magnitude of the problem and identification of hotspot areas are necessary. Analysis of remote sensing and climate data observed from space for the period 1982 - 2003 showed significant improvement in vegetation productivity across 30% of SSA with decline on 5% of the subcontinent. Global change in atmospheric chemistry is likely responsible for the observed increasing trend in vegetation productivity. Such widespread greening observed from space could mask anthropogenic land degradation processes such as land conversion, selective logging, and soil nutrient mining. To assess this possible masking effect, a re-analysis of the vegetation productivity dynamics, taking into account atmospheric fertilization, was conducted. This was performed by analyzing the long-term trend in vegetation productivity of pristine lands (areas with minimum human- and climate- related impacts) identified across different biomes in SSA. The baseline slope values of biomass accrual calculated for those pristine lands were estimated and used to re-calculate the long-term trend of green biomass with and without the impact of atmospheric fertilization. This ultimately enabled to delineate the areas that would have experienced significant loss in vegetation productivity had the atmospheric chemistry not changed. The result suggests that seven times more than the area of actual productivity decline in SSA is affected by land degradation processes that are concealed by atmospheric fertilization. With this rate of surreptitious loss of vital land attributes and with the current rate of population growth (3%), the SSA subcontinent may soon lack the land resources necessary to foster economic development. Spatially

  4. Glacial interglacial rain ratio changes: Implications for atmospheric CO2 and ocean sediment interaction

    Science.gov (United States)

    Munhoven, Guy

    2007-03-01

    A reduction of the carbonate-carbon to organic-carbon export rain ratio during glacial times has been advanced to explain the glacial-interglacial atmospheric CO2 variations. This hypothesis is tested and implications for the dynamics of sedimentary carbonate preservation and dissolution are explored with a multi-box model ( MBM) of the ocean carbon cycle, fully coupled to a new transient early diagenesis model (called MEDUSA). A peak reduction of the rain ratio by 40% at the Last Glacial Maximum (LGM) was found to produce a net atmospheric pCO2 reduction of about 40 ppm. Changing shelf carbonate accumulation rates and continental weathering inputs produced a 55-60 ppm reduction. The combination of the two mechanisms generates a pCO2 change of 90-95 ppm, which compares well with the observed data. However, the resulting model sedimentary record does not conform to actual sedimentary records. The changes related to continental shelf processes and variable weathering flux depress the calcite saturation horizon (CSH) by about 1 km at the LGM; if rain ratio variations are also considered, that depression increases by another km. In addition to this large amplitude for the CSH, possibly due to the adopted box-model approach, the changing rain ratio also leads to transition zone changes in the model sedimentary record that are opposite in phase with data-based reconstructions. Realistic changes in the aragonite fraction of the carbonate rain were found to have only a minimal impact on atmospheric pCO2. Finally, chemical erosion of deep-sea sediment was shown to reduce the amplitude of variation of the sedimentary CCD by about 10-20%. It may provide a mechanism to improve the model-data agreement.

  5. Vehicular fuel composition and atmospheric emissions in South China: Hong Kong, Macau, Guangzhou, and Zhuhai

    Directory of Open Access Journals (Sweden)

    W. Y. Tsai

    2006-05-01

    Full Text Available Vehicular emission is an important source of air pollutants in urban cities in the Pearl River Delta (PRD region of South China. In order to study the impact of vehicular fuel on air quality, several commonly used fuel samples were collected in four main cities in the PRD region – Hong Kong, Guangzhou, Macau and Zhuhai, and analyzed for their volatile organic compounds (VOCs composition. Source profiles of the vehicular fuels used in these cities were constructed and are believed to be the first reported for the PRD region. The C8–C10 hydrocarbons were the main constituents of diesel. Different from diesel, gasoline used in the PRD region was mainly comprised of lighter C4–C7 hydrocarbons, with toluene and i-pentane being the two most abundant species. The benzene content in the Guangzhou and Zhuhai gasoline samples were higher than that in Hong Kong and Macau and exceeded the maximum benzene levels for Mainland China unleaded gasoline. Liquefied Petroleum Gas (LPG samples were collected only in Hong Kong and were comprised mainly of n-butane, propane and i-butane. Traffic samples indicated that evaporative loss and vehicular combustion were the primary contributors to elevated VOC levels in roadside atmospheres. Significant i-pentane and toluene concentrations were observed in roadside atmospheres in all four cities. Ratio of i-pentane in gasoline samples to that in roadside samples were calculated and this showed that the degree of evaporative loss was higher in Guangzhou and Zhuhai than that in Hong Kong and Macau. We suggest the difference is due to the better maintenance and more new cars in Hong Kong and Macau. From tunnel samples collected in Hong Kong in two different years, we found that the relative amount of propane, i-butane, and n-butane increased between 2001 to 2003, consistent with the 40% increase in LPG fueled vehicles. Propane to butanes ratios were calculated for LPG and

  6. Vehicular fuel composition and atmospheric emissions in South China: Hong Kong, Macau, Guangzhou, and Zhuhai

    Directory of Open Access Journals (Sweden)

    W. Y. Tsai

    2006-01-01

    Full Text Available Vehicular emission is an important source of air pollutants in urban cities in the Pearl River Delta (PRD region of South China. In order to study the impact of evaporative loss of vehicular fuel on air quality, several commonly used fuel samples were collected in four main cities in the PRD region – Hong Kong, Guangzhou, Macau and Zhuhai, and analyzed for their volatile organic compounds (VOCs composition. Source profiles of vapors of the vehicular fuels used in these cities were constructed and are believed to be the first reported for the PRD region. The C8-C10 hydrocarbons were the main constituents of diesel. Different from diesel, gasoline used in the PRD region was mainly comprised of lighter C4-C7 hydrocarbons, with toluene and i-pentane being the two most abundant species. The toluene content in the Hong Kong and Macau gasoline samples were higher than that in Guangzhou and Zhuhai, while the reverse was true for the benzene content. The benzene levels in Guangzhou and Zhuhai exceeded the maximum allowable benzene levels for Mainland China unleaded gasoline. Liquefied Petroleum Gas (LPG samples were collected only in Hong Kong and were comprised mainly of n-butane, propane and i-butane. Traffic samples indicated that evaporative loss and vehicular combustion were the primary contributors to elevated VOC levels in roadside atmospheres. Significant i-pentane and toluene concentrations were observed in roadside atmospheres in all four cities. Ratio of i-pentane in gasoline vapors to that in roadside samples were calculated and this showed that the degree of evaporative loss were higher in Guangzhou and Zhuhai than that in Hong Kong and Macau. We suggest the difference is due to the better maintenance and more new cars in Hong Kong and Macau. From tunnel samples collected in Hong Kong in two different years, we found that the relative amount of propane, i-butane, and n-butane increased between 2001 to 2003, consistent with the 40% increase

  7. Vehicular fuel composition and atmospheric emissions in South China: Hong Kong, Macau, Guangzhou, and Zhuhai

    Science.gov (United States)

    Tsai, W. Y.; Chan, L. Y.; Blake, D. R.; Chu, K. W.

    2006-08-01

    Vehicular emission is an important source of air pollutants in urban cities in the Pearl River Delta (PRD) region of South China. In order to study the impact of evaporative loss of vehicular fuel on air quality, several commonly used fuel samples were collected in four main cities in the PRD region - Hong Kong, Guangzhou, Macau and Zhuhai, and analyzed for their volatile organic compounds (VOCs) composition. Source profiles of vapors of the vehicular fuels used in these cities were constructed and are believed to be the first reported for the PRD region. The C8-C10 hydrocarbons were the main constituents of diesel. Different from diesel, gasoline used in the PRD region was mainly comprised of lighter C4-C7 hydrocarbons, with toluene and i-pentane being the two most abundant species. The toluene content in the Hong Kong and Macau gasoline samples were higher than that in Guangzhou and Zhuhai, while the reverse was true for the benzene content. The benzene levels in Guangzhou and Zhuhai exceeded the maximum allowable benzene levels for Mainland China unleaded gasoline. Liquefied Petroleum Gas (LPG) samples were collected only in Hong Kong and were comprised mainly of n-butane, propane and i-butane. Traffic samples indicated that evaporative loss and vehicular combustion were the primary contributors to elevated VOC levels in roadside atmospheres. Significant i-pentane and toluene concentrations were observed in roadside atmospheres in all four cities. Ratio of i-pentane in gasoline vapors to that in roadside samples were calculated and this showed that the degree of evaporative loss were higher in Guangzhou and Zhuhai than that in Hong Kong and Macau. We suggest the difference is due to the better maintenance and more new cars in Hong Kong and Macau. From tunnel samples collected in Hong Kong in two different years, we found that the relative amount of propane, i-butane, and n-butane increased between 2001 to 2003, consistent with the 40% increase in LPG fueled

  8. Southwestern Tropical Atlantic coral growth response to atmospheric circulation changes induced by ozone depletion in Antarctica

    Directory of Open Access Journals (Sweden)

    H. Evangelista

    2015-08-01

    Full Text Available Climate changes induced by stratospheric ozone depletion over Antarctica have been recognized as an important consequence of the recently observed Southern Hemisphere atmospheric circulation. Here we present evidences that the Brazilian coast (Southwestern Atlantic may have been impacted from both winds and sea surface temperature changes derived from this process. Skeleton analysis of massive coral species living in shallow waters off Brazil are very sensitive to air–sea interactions, and seem to record this impact. Growth rates of Brazilian corals show a trend reversal that fits the ozone depletion evolution, confirming that ozone impacts are far reaching and potentially affect coastal ecosystems in tropical environments.

  9. The Changing Cold Regions Network: Atmospheric, Cryospheric, Ecological and Hydrological Change in the Saskatchewan and Mackenzie River Basins, Canada (Invited)

    Science.gov (United States)

    Wheater, H. S.; DeBeer, C.

    2013-12-01

    The cold interior of Northwestern Canada has one of the world's most extreme and varied climates and, as with other regions across the Arctic, is experiencing rapid environmental change. The Changing Cold Regions Network (CCRN) is a new Canadian research network devoted to addressing key challenges and globally-important issues facing the Arctic by improving the understanding of past and ongoing changes in climate, land, vegetation, and water, and predicting their future integrated responses, with a geographic focus on the Saskatchewan and Mackenzie River Basins. The network is funded for 5 years (2013-18) by the Natural Sciences and Engineering Research Council of Canada, and combines the unique expertise of 36 Canadian scientists representing 8 universities and 4 Federal government agencies, as well as 15 international researchers from the United States, China, Australia, the UK, France, and Germany. The network will also involve the World Climate Research Programme, NASA, the Canadian Space Agency, and the National Center for Atmospheric Research. CCRN will integrate existing and new experimental data with modelling and remote sensing products to understand, diagnose and predict changing land, water and climate, and their interactions and feedbacks, for Northwestern Canada's cold interior. It will use a network of world class observatories to study the detailed connections among changing climate, ecosystems and water in the permafrost regions of the Sub-arctic, the Boreal Forest, the Western Cordillera, and the Prairies. Specifically, the network will: 1. Document and evaluate observed Earth system change, including hydrological, ecological, cryospheric and atmospheric components over a range of scales from local observatories to biome and regional scales; 2. Improve understanding and diagnosis of local-scale change by developing new and integrative knowledge of Earth system processes, incorporating these processes into a suite of process-based integrative

  10. Sensitivity of direct climate forcing by atmospheric aerosols to aerosol size and composition

    Science.gov (United States)

    Pilinis, Christodoulos; Pandis, Spyros N.; Seinfeld, John H.

    1995-09-01

    We evaluate, using a box model, the sensitivity of direct climate forcing by atmospheric aerosols for a "global mean" aerosol that consists of fine and coarse modes to aerosol composition, aerosol size distribution, relative humidity (RH), aerosol mixing state (internal versus external mixture), deliquescence/crystallization hysteresis, and solar zenith angle. We also examine the dependence of aerosol upscatter fraction on aerosol size, solar zenith angle, and wavelength and the dependence of single scatter albedo on wavelength and aerosol composition. The single most important parameter in determining direct aerosol forcing is relative humidity, and the most important process is the increase of the aerosol mass as a result of water uptake. An increase of the relative humidity from 40 to 80% is estimated for the global mean aerosol considered to result in an increase of the radiative forcing by a factor of 2.1. Forcing is relatively insensitive to the fine mode diameter increase due to hygroscopic growth, as long as this mode remains inside the efficient scattering size region. The hysteresis/deliquescence region introduces additional uncertainty but, in general, errors less than 20% result by the use of the average of the two curves to predict forcing. For fine aerosol mode mean diameters in the 0.2-0.5 μm range direct aerosol forcing is relatively insensitive (errors less than 20%) to variations of the mean diameter. Estimation of the coarse mode diameter within a factor of 2 is generally sufficient for the estimation of the total aerosol radiative forcing within 20%. Moreover, the coarse mode, which represents the nonanthropogenic fraction of the aerosol, is estimated to contribute less than 10% of the total radiative forcing for all RHs of interest. Aerosol chemical composition is important to direct radiative forcing as it determines (1) water uptake with RH, and (2) optical properties. The effect of absorption by aerosol components on forcing is found to be

  11. Weather forecasting by insects: modified sexual behaviour in response to atmospheric pressure changes.

    Science.gov (United States)

    Pellegrino, Ana Cristina; Peñaflor, Maria Fernanda Gomes Villalba; Nardi, Cristiane; Bezner-Kerr, Wayne; Guglielmo, Christopher G; Bento, José Maurício Simões; McNeil, Jeremy N

    2013-01-01

    Prevailing abiotic conditions may positively or negatively impact insects at both the individual and population levels. For example while moderate rainfall and wind velocity may provide conditions that favour development, as well as movement within and between habitats, high winds and heavy rains can significantly decrease life expectancy. There is some evidence that insects adjust their behaviours associated with flight, mating and foraging in response to changes in barometric pressure. We studied changes in different mating behaviours of three taxonomically unrelated insects, the curcurbit beetle, Diabrotica speciosa (Coleoptera), the true armyworm moth, Pseudaletia unipuncta (Lepidoptera) and the potato aphid, Macrosiphum euphorbiae (Hemiptera), when subjected to natural or experimentally manipulated changes in atmospheric pressure. In response to decreasing barometric pressure, male beetles exhibited decreased locomotory activity in a Y-tube olfactometer with female pheromone extracts. However, when placed in close proximity to females, they exhibited reduced courtship sequences and the precopulatory period. Under the same situations, females of the true armyworm and the potato aphid exhibited significantly reduced calling behaviour. Neither the movement of male beetles nor the calling of armyworm females differed between stable and increasing atmospheric pressure conditions. However, in the case of the armyworm there was a significant decrease in the incidence of mating under rising atmospheric conditions, suggesting an effect on male behaviour. When atmospheric pressure rose, very few M. euphorbiae oviparae called. This was similar to the situation observed under decreasing conditions, and consequently very little mating was observed in this species except under stable conditions. All species exhibited behavioural modifications, but there were interspecific differences related to size-related flight ability and the diel periodicity of mating activity. We

  12. Changes in atmospheric aerosol loading retrieved from space based measurements during the past decade

    Directory of Open Access Journals (Sweden)

    J. Yoon

    2013-10-01

    Full Text Available Atmospheric aerosol, generated from natural and anthropogenic sources, plays a key role in regulating visibility, air quality, and acid deposition. It is directly linked to and impacts on human health. It also reflects and absorbs incoming solar radiation and thereby influences the climate change. The cooling by aerosols is now recognized to have partly masked the atmospheric warming from fossil fuel combustion emissions. The role and potential management of short-lived climate pollutants such as aerosol are currently a topic of much scientific and public debate. Our limited knowledge of atmospheric aerosol and its influence on the Earth's radiation balance has a significant impact on the accuracy and error of current predictions of the future global climate change. In the past decades, environmental legislation in industrialized countries has begun to limit the release of anthropogenic pollutants. In contrast, in Asia as a result of the recent rapid economic development, emissions from industry and traffic have increased dramatically. In this study, the temporal changes/trends of atmospheric aerosols, derived from the satellite instruments MODIS (on board Terra and Aqua, MISR (Terra, and SeaWiFS (OrbView-2 during the past decade, are investigated. Whilst the aerosol optical thickness, AOT, over Western Europe decreases (i.e. by up to about −40% from 2003 to 2008 and parts of North America, a statistically significant increase (about +34% in the same period over East China is observed and attributed to both the increase in industrial output and the Asian desert dust.

  13. Projected changes in atmospheric river events in Arizona as simulated by global and regional climate models

    Science.gov (United States)

    Rivera, Erick R.; Dominguez, Francina

    2016-09-01

    Inland-penetrating atmospheric rivers (ARs) affect the United States Southwest and significantly contribute to cool season precipitation. In this study, we examine the results from an ensemble of dynamically downscaled simulations from the North American Regional Climate Change Assessment Program (NARCCAP) and their driving general circulation models (GCMs) in order to determine statistically significant changes in the intensity of the cool season ARs impacting Arizona and the associated precipitation. Future greenhouse gas emissions follow the A2 emission scenario from the Intergovernmental Panel on Climate Change Fourth Assessment Report simulations. We find that there is a consistent and clear intensification of the AR-related water vapor transport in both the global and regional simulations which reflects the increase in water vapor content due to warmer atmospheric temperatures, according to the Clausius-Clapeyron relationship. However, the response of AR-related precipitation intensity to increased moisture flux and column-integrated water vapor is weak and no significant changes are projected either by the GCMs or the NARCCAP models. This lack of robust precipitation variations can be explained in part by the absence of meaningful changes in both the large-scale water vapor flux convergence and the maximum positive relative vorticity in the GCMs. Additionally, some global models show a robust decrease in relative humidity which may also be responsible for the projected precipitation patterns.

  14. Postnatal changes in fatty acids composition of brown adipose tissue

    Science.gov (United States)

    Ohno, T.; Ogawa, K.; Kuroshima, A.

    1992-03-01

    It has been demonstrated that thermogenic activity of brown adipose tissue (BAT) is higher during the early postnatal period, decreasing towards a low adult level. The present study examined postnatal changes in the lipid composition of BAT. BAT from pre-weaning rats at 4 and 14 days old showed the following differences in lipid composition compared to that from adults of 12 weeks old. (i) Relative weight of interscapular BAT to body weight was markedly greater. (ii) BAT-triglyceride (TG) level was lower, while BAT-phospholipid (PL)level was higher. (iii) In TG fatty acids (FA) polyunsaturated fatty acids (PU; mol %), arachidonate index (AI), unsaturation index (UI) and PU/saturated FA (SA) were higher; rare FA such as eicosadienoate, bishomo- γ-linolenic acid and lignoceric acid in mol % were also higher. (iv) In PL-FA monounsaturated FA (MU) in mol % was lower; PU mol %, AI and UI were higher. These features in BAT of pre-weaning rats resembled those in the cold-acclimated adults, suggesting a close relationship of the PL-FA profile to high activity of BAT.

  15. Atmospheric aerosol compositions and sources at two national background sites in northern and southern China

    Science.gov (United States)

    Zhu, Qiao; He, Ling-Yan; Huang, Xiao-Feng; Cao, Li-Ming; Gong, Zhao-Heng; Wang, Chuan; Zhuang, Xin; Hu, Min

    2016-08-01

    Although China's severe air pollution has become a focus in the field of atmospheric chemistry and the mechanisms of urban air pollution there have been researched extensively, few field sampling campaigns have been conducted at remote background sites in China, where air pollution characteristics on a larger scale are highlighted. In this study, an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), together with an Aethalometer, was deployed at two of China's national background sites in northern (Lake Hongze site; 33.23° N, 118.33° E; altitude 21 m) and southern (Mount Wuzhi site; 18.84° N, 109.49° E; altitude 958 m) China in the spring seasons in 2011 and 2015, respectively, in order to characterize submicron aerosol composition and sources. The campaign-average PM1 concentration was 36.8 ± 19.8 µg m-3 at the northern China background (NCB) site, which was far higher than that at the southern China background (SCB) site (10.9 ± 7.8 µg m-3). Organic aerosol (OA) (27.2 %), nitrate (26.7 %), and sulfate (22.0 %) contributed the most to the PM1 mass at NCB, while OA (43.5 %) and sulfate (30.5 %) were the most abundant components of the PM1 mass at SCB, where nitrate only constituted a small fraction (4.7 %) and might have contained a significant amount of organic nitrates (5-11 %). The aerosol size distributions and organic aerosol elemental compositions all indicated very aged aerosol particles at both sites. The OA at SCB was more oxidized with a higher average oxygen to carbon (O / C) ratio (0.98) than that at NCB (0.67). Positive matrix factorization (PMF) analysis was used to classify OA into three components, including a hydrocarbon-like component (HOA, attributed to fossil fuel combustion) and two oxygenated components (OOA1 and OOA2, attributed to secondary organic aerosols from different source areas) at NCB. PMF analysis at SCB identified a semi-volatile oxygenated component (SV-OOA) and a low-volatility oxygenated

  16. Characteristics and Composition of Atmospheric Aerosols in Phimai, Central Thailand During BASE-ASIA

    Science.gov (United States)

    Li, Can; Tsay, Si-Chee; Hsu, N. Christina; Kim, Jin Young; Howell, Steven G.; Huebert, Barry J.; Ji, Qiang; Jeong, Myeong-Jae; Wang, Sheng-Hsiang; Hansell, Richard A.; Bell, Shaun W.

    2012-01-01

    Popular summary: Atmospheric aerosols play an important role in the Earth's climate system, and can also have adverse effects on air quality and human health. The environmental impacts of aerosols, on the other hand, are highly regional, since their temporal/spatial distribution is inhomogeneous and highly depends on the regional emission sources. To better understand the effects of aerosols, intensive field experiments are necessary to characterize the chemical and physical properties on a region-by-region basis. From late February to early May in 2006, NASA/GSFC's SMARTLabs facility was deployed at a rural site in central Thailand, Southeast Asia, to conduct a field experiment dubbed BASE-ASIA (Biomass-burning Aerosols in South East-Asia: Smoke Impact Assessment). The group was joined by scientists from the University of Hawaii and other regional institutes. Comprehensive measurements were made during the experiment, including aerosol chemical composition, optical and microphysical properties, as well as surface energetics and local . meteorology. This study analyzes part of the data from the BASE-ASIA experiment. It was found that, even for the relatively remote rural site, the aerosol loading was still substantial. Besides agricultural burning in the area, industrial pollution near the Bangkok metropolitan area, about 200 km southeast of the site, and even long-range transport from China, also contribute to the area's aerosol loading. The results indicate that aerosol pollution has developed into a regional problem for northern Indochina, and may become more severe as the region's population and economy continue to grow. Abstract: Comprehensive measurements of atmospheric aerosols were made in Phimai, central Thailand (15.l83 N, 102.565 E, elevation: 206 m) during the BASE-ASIA field experiment from late February to early May in 2006. The observed aerosol loading was sizable for this rural site (mean aerosol scattering: 108 +/- 64 Mm(exp -1); absorption: 15

  17. The summer 2012 Greenland heat wave: monitoring water vapour isotopic composition along an atmospheric river event

    Science.gov (United States)

    Bonne, Jean-Louis; Steen-Larsen, Hans Christian; Masson-Delmotte, Valérie; Sodemann, Harald; Lacour, Jean-Lionel; Risi, Camille; Werner, Martin; Clerbaux, Cathy; Fettweis, Xavier

    2014-05-01

    In July 2012, an extreme warm event occurred in Greenland, leading to surface melt over almost all the ice sheet. This event was recorded in the isotopic composition of water vapour measured by the IASI satellite along the transport pathway and at two sites where continuous in situ surface vapour isotopic measurements were conducted, situated at a coastal station of South Greenland (Ivittuut) and further North on top of the ice sheet (NEEM, NW Greenland). These observations allowed us to monitor the isotopic composition of the air mass at different stages of its advection towards Greenland, which can inform on processes along this trajectory, such as cloud properties and moisture sources. In addition, two simulations of this event, using the atmospheric general circulation models LMDZiso and ECHAM5wiso equipped with water stable isotopes and nudged towards large scale wind fields, are investigated. Furthermore, a regional high-resolution model was used to study the moisture transport to Greenland during this event using tagged water tracers of the North Atlantic ocean and coastal land evaporation. Using moisture source diagnostic based on the Lagrangian particle dispersion model Flexpart, we show that this 2012 heat wave event corresponds to moisture sources located over the subtropical Atlantic Ocean, where intense evaporation was caused by dry air masses associated with the US intense summer drought. This moisture was then advected northward along a narrow band, due to a very stationary surface cyclone southwest of Greenland, reached southern Greenland and Ivittuut coastal station on July 9th, travelled along the west coast of Greenland, continued eastwards above the ice sheet and arrived above the NEEM deep drilling camp on July 11th. Surface isotopic observations during the event show larger variations at NEEM than in Ivittuut, strongly reducing the isotopic and deuterium excess latitudinal gradient usually observed between South and North Greenland. This

  18. Composition change and capacitance properties of ruthenium oxide thin film

    Institute of Scientific and Technical Information of China (English)

    刘泓; 甘卫平; 刘仲武; 郑峰

    2015-01-01

    RuO2·nH2O film was deposited on tantalum foils by electrodeposition and heat treatment using RuCl3·3H2O as precursor. Surface morphology, composition change and cyclic voltammetry from precursor to amorphous and crystalline RuO2·nH2O films were studied by X-ray diffractometer, Fourier transformation infrared spectrometer, differential thermal analyzer, scanning electron microscope and electrochemical analyzer, respectively. The results show that the precursor was transformed gradually from amorphous to crystalline phase with temperature. When heat treated at 300 °C for 2 h, RuO2·nH2O electrode surface gains mass of 2.5 mg/cm2 with specific capacitance of 782 F/g. Besides, it is found that the specific capacitance of the film decreased by roughly 20%with voltage scan rate increasing from 5 to 250 mV/s.

  19. Changes in the Composition of Aromatherapeutic Citrus Oils during Evaporation

    Directory of Open Access Journals (Sweden)

    George W. Francis

    2015-01-01

    Full Text Available The composition of some commercial Citrus oils, lemon, sweet orange, and tangerine, designated for aromatherapy, was examined before and after partial evaporation in a stream of nitrogen. The intact oils contained the expected mixtures of mono- and sesquiterpenes, with hydrocarbons dominating and lesser amounts of oxygenated analogues making up the remainder. Gas chromatography-mass spectrometry was used to follow alterations in the relative amounts of the various components present as evaporation proceeded. Changes were marked, and in particular more volatile components present in the intact oils rapidly disappeared. Thus the balance of content was shifted away from monoterpene hydrocarbons towards the analogous alcohols and carbonyl compounds. The results of this differential evaporation are discussed and possible consequences for aromatherapy use are noted. The case of lemon oil was especially interesting as the relative amount of citral, a known sensitizer, remaining as time elapsed represented an increasing percentage of the total oil.

  20. Decadal changes in North Atlantic atmospheric circulation patterns recorded by sand spits since 1800 CE

    Science.gov (United States)

    Poirier, Clément; Tessier, Bernadette; Chaumillon, Éric; Bertin, Xavier; Fruergaard, Mikkel; Mouazé, Dominique; Noël, Suzanne; Weill, Pierre; Wöppelmann, Guy

    2017-03-01

    Present-day coastal barriers represent around 15% of the world's oceanic shorelines, and play an important role as early warning indicators of environmental change. Among them, wave-dominated barriers are dynamic landforms that tend to migrate landward in response to storms and sea-level change. High rates of sediment supply can locally offset the global retrogradation trend, providing valuable records of past environmental change occurring on transgressive coasts. However, geochronological control limits the temporal resolution of such records to millennial or centennial timescales, and the decadal or even faster response of wave-built barriers to historical climate changes is therefore poorly understood. In this study, we show that shoreline dynamics of sand spits reconstructed from old cartographic documents has been synchronous on both margins of the North Atlantic Ocean since about 1800 CE. Spit growth accelerated drastically during three periods lasting about 15 years, characterised by positive North Atlantic Oscillation (NAO) and negative East Atlantic-West Russia (EA-WR) atmospheric circulation patterns. These changes are in phase with periods of increased volcanic activity. We use a high-resolution wave hindcast (1948-2014 CE) in a reference area to confirm the association between NAO and EA-WR as a proxy for offshore and nearshore wave height and for associated longshore sediment transport (LST) involved in spit growth. A 24-month lagged correlation between sediment transport and volcanic aerosol optical thickness (concentration of ashes in the atmosphere) is observed, suggesting that spit shoreline dynamics at the decadal timescale is partially forced by external climate drivers via cascading effects on atmospheric circulation patterns and wave climate. Our results imply that NAO variability alone is not sufficient to understand the evolution of wave-built coastal environments. The associated sediment record can be used to reconstruct multi

  1. Analysis on Infrared Spectrometer System Specification for Atmospheric Composition Detecting%大气成分探测红外光谱仪系统指标分析

    Institute of Scientific and Technical Information of China (English)

    齐卫红; 尉昊赟; 阴丽娜

    2013-01-01

    由温室气体引起的全球气候变化和环境污染已经受到全世界的广泛关注。进行大气成分探测,对于更好地了解温室效应产生的细节、大气分子的光化学性质对臭氧层的影响以及大气污染机制都具有重要意义。由于大气成分种类较多,其红外吸收光谱密集且复杂,因此大气成分探测仪器需要有较高的光谱分辨能力和信噪比。文章进行了大气成分探测的总体指标需求分析,并据此确定了大气成分探测红外光谱仪的主要技术指标。为了满足指标要求,该光谱仪采用傅里叶变换红外光谱仪的总体方案。通过仪器性能影响因素分析和系统优化,使得该仪器的最终设计结果满足指标要求。%Global climate change and environmental pollution caused by greenhouse gases has received ex-tensive attention all over the world. Detecting atmospheric composition is especial important for a better under-standing of the detail of the green house effect, the influences on the ozonosphere of atmospheric photochemistry, as well as the mechanism of the air pollution. Because the kinds of atmospheric composition and their infrared absorption spectral lines are very dense and complex, atmospheric composition instruments need to have high spectral resolution and high signal-to-noise ratio (SNR). This report briefly introduced the specification require-ment analysis for space atmospheric detecting, and the main specifications of the instrument for space atmospher-ic detecting are defined. For realizing the main specifications, the overall scheme of the instrument adopts Fourier Transform Infrared Spectrometer (FTIRS). The final design of the instrument meets the specifications through influence factor analysis and system optimization. Finally, the measurement result was given.

  2. Changes in tropospheric composition and air quality due to stratospheric ozone depletion and climate change.

    Science.gov (United States)

    Wilson, S R; Solomon, K R; Tang, X

    2007-03-01

    It is well-understood that reductions in air quality play a significant role in both environmental and human health. Interactions between ozone depletion and global climate change will significantly alter atmospheric chemistry which, in turn, will cause changes in concentrations of natural and human-made gases and aerosols. Models predict that tropospheric ozone near the surface will increase globally by up to 10 to 30 ppbv (33 to 100% increase) during the period 2000 to 2100. With the increase in the amount of the stratospheric ozone, increased transport from the stratosphere to the troposphere will result in different responses in polluted and unpolluted areas. In contrast, global changes in tropospheric hydroxyl radical (OH) are not predicted to be large, except where influenced by the presence of oxidizable organic matter, such as from large-scale forest fires. Recent measurements in a relatively clean location over 5 years showed that OH concentrations can be predicted by the intensity of solar ultraviolet radiation. If this relationship is confirmed by further observations, this approach could be used to simplify assessments of air quality. Analysis of surface-level ozone observations in Antarctica suggests that there has been a significant change in the chemistry of the boundary layer of the atmosphere in this region as a result of stratospheric ozone depletion. The oxidation potential of the Antarctic boundary layer is estimated to be greater now than before the development of the ozone hole. Recent modeling studies have suggested that iodine and iodine-containing substances from natural sources, such as the ocean, may increase stratospheric ozone depletion significantly in polar regions during spring. Given the uncertainty of the fate of iodine in the stratosphere, the results may also be relevant for stratospheric ozone depletion and measurements of the influence of these substances on ozone depletion should be considered in the future. In agreement with

  3. Constraining the Atmospheric Composition of the Day-Night Terminators of HD 189733b : Atmospheric Retrieval with Condensates

    CERN Document Server

    Lee, Jae-Min; Leigh,; Fletcher, N; Heng, Kevin; Barstow, Joanna K

    2013-01-01

    Rayleigh scattering by condensates characterises the transmission spectrum of HD 189733b at wavelengths shortward of 1 $\\mu$m. We retrieve a range of condensate distributions consistent with transmission spectroscopy between 0.3-24 $\\mu$m that were recently re-analyzed by Pont et al.(2013). We suggest that a vertically-confined condensate layer with a monodisperse particle size of about 0.06 $\\mu$m and an optical depth of about 0.6 at wavelength 1 $\\mu$m provides the best atmospheric scenario for the terminator regions of HD 189733b. Generally, we find that both vertically-confined and uniform condensate layers suggest plausible fits to the data if the optical depth is 0.1-3 and the particle size is smaller than 0.1 $\\mu$m. Strong constraints on the condensate properties are provided by spectra at wavelengths shortward of 1 $\\mu$m as well as longward of 8 $\\mu$m. We show that these are the optimal wavelengths for quantifying the effects of condensates, which may guide the design of future space observations. ...

  4. Exo-Transmit: An Open-Source Code for Calculating Transmission Spectra for Exoplanet Atmospheres of Varied Composition

    Science.gov (United States)

    Kempton, Eliza M.-R.; Lupu, Roxana; Owusu-Asare, Albert; Slough, Patrick; Cale, Bryson

    2017-04-01

    We present Exo-Transmit, a software package to calculate exoplanet transmission spectra for planets of varied composition. The code is designed to generate spectra of planets with a wide range of atmospheric composition, temperature, surface gravity, and size, and is therefore applicable to exoplanets ranging in mass and size from hot Jupiters down to rocky super-Earths. Spectra can be generated with or without clouds or hazes with options to (1) include an optically thick cloud deck at a user-specified atmospheric pressure or (2) to augment the nominal Rayleigh scattering by a user-specified factor. The Exo-Transmit code is written in C and is extremely easy to use. Typically the user will only need to edit parameters in a single user input file in order to run the code for a planet of their choosing. Exo-Transmit is available publicly on Github with open-source licensing at https://github.com/elizakempton/Exo_Transmit.

  5. Exo-Transmit: An Open-Source Code for Calculating Transmission Spectra for Exoplanet Atmospheres of Varied Composition

    CERN Document Server

    Kempton, Eliza M -R; Owusu-Asare, Albert; Slough, Patrick; Cale, Bryson

    2016-01-01

    We present Exo-Transmit, a software package to calculate exoplanet transmission spectra for planets of varied composition. The code is designed to generate spectra of planets with a wide range of atmospheric composition, temperature, surface gravity, and size, and is therefore applicable to exoplanets ranging in mass and size from hot Jupiters down to rocky super-Earths. Spectra can be generated with or without clouds or hazes with options to (1) include an optically thick cloud deck at a user-specified atmospheric pressure or (2) to augment the nominal Rayleigh scattering by a user-specified factor. The Exo-Transmit code is written in C and is extremely easy to use. Typically the user will only need to edit parameters in a single user input file in order to run the code for a planet of their choosing. Exo-Transmit is available publicly on Github with open-source licensing at https://github.com/elizakempton/Exo_Transmit .

  6. Erosion behaviour of composite Al-Cr cathodes in cathodic arc plasmas in inert and reactive atmospheres

    CERN Document Server

    Franz, Robert; Hawranek, Gerhard; Polcik, Peter

    2015-01-01

    Al$_{x}$Cr$_{1-x}$ composite cathodes with Al contents of x = 0.75, 0.5 and 0.25 were exposed to cathodic arc plasmas in Ar, N$_2$ and O$_2$ atmospheres and their erosion behaviour was studied. Cross-sectional analysis of the elemental distribution of the near-surface zone in the cathodes by scanning electron microscopy revealed the formation of a modified layer for all cathodes and atmospheres. Due to intermixing of Al and Cr in the heat-affected zone, intermetallic Al-Cr phases formed as evidenced by X-ray diffraction analysis. Cathode poisoning effects in the reactive N$_2$ and O$_2$ atmospheres were non-uniform as a result of the applied magnetic field configuration. With the exception of oxide islands on Al-rich cathodes, reactive layers were absent in the circular erosion zone, while nitrides and oxides formed in the less eroded centre region of the cathodes.

  7. Comparison between methods for the determination of the primary cosmic ray mass composition from the longitudinal profile of atmospheric cascades

    CERN Document Server

    Ambrosio, M; Donalek, C; D'Urso, D; Erlykin, A D; Guarino, F; Insoiia, A; Longo, G

    2005-01-01

    The determination of the primary cosmic ray mass composition from the longitudinal development of atmospheric cascades is still a debated issue. In this work we discuss several data analysis methods and show that if the entire information contained in the longitudinal profile is exploited, reliable results may be obtained. Among the proposed methods FCC ('Fit of the Cascade Curve'), MTA ('Multiparametric Topological Analysis') and NNA ('Neural Net Analysis') with conjugate gradient optimization algorithm give the best accuracy.

  8. Future changes in atmospheric circulation types and related precipitation extremes in Central Europe

    Science.gov (United States)

    Homann, Markus; Jacobeit, Jucundus; Beck, Christoph; Philipp, Andreas

    2016-04-01

    The statistical evaluation of the relationships between atmospheric circulation types and areal precipitation events took place in the context of an international project called WETRAX (Weather patterns, storm tracks and related precipitation extremes). The aim of the project was to estimate the regional flooding potential in Central Europe under enhanced climate change conditions. For parts of southern Central Europe, a gridded daily precipitation set with 6km horizontal resolution has been generated for the period 1951-2006 by the Austrian Zentralanstalt für Meteorologie und Geodynamik (ZAMG). To determine regions with similar precipitation variability, a S-mode principal component analysis has been applied. Extreme precipitation events are defined by the 95% percentile, based on regional arithmetic means of daily precipitation. Large-scale atmospheric circulation types have been derived by different statistical methods and variables using the COST733 classification software and gridded daily NCEP1 reanalysis data. To evaluate the performance of a particular circulation type classification with respect to regional precipitation extremes, multiple regression models have been derived between the circulation type frequencies as predictor variables and monthly frequencies of extreme precipitation as well as monthly rainfall amounts from these events. To estimate the regional flooding potential in Central Europe under enhanced climate change conditions, multiple regression models are applied to different projected GCM predictor data. Thus, future changes in circulation type occurrence frequencies are transferred into assessments of future changes in precipitation extremes on a regional scale.

  9. Composition of semi-volatile organic compounds in the urban atmosphere of Singapore: influence of biomass burning

    Directory of Open Access Journals (Sweden)

    J. He

    2010-04-01

    Full Text Available An intensive field study was conducted in the urban atmosphere of Singapore to investigate the composition of organic compounds in both gaseous and particulate phases during the period of August to early November 2006. 17 atmospheric samples were collected. These samples were subjected to accelerated solvent extraction with a mixture of dichloromethane and acetone and separated into functional group fractions for analyses by GC/MS. Over 180 organic compounds belonging to three major fractions (n-alkanes, polycyclic aromatic hydrocarbons (PAHs, and polar organic compounds (POCs were identified and quantified. The characteristics and abundance of the n-alkanes, PAHs, mono and dicarboxylic acids, methoxylated phenols and other POCs were determined. The composition of these organic compounds fluctuated temporally with most of them being relatively higher in October than those in other months of the sampling period. 3-D backward air mass trajectory analyses together with the carbon preference index (CPI, molecular diagnostic ratios and molecular markers were used to investigate the origin of organic species measured in this study. Based on these diagnostic tools, the increased abundance of atmospheric organic species during October could be attributed to the occurrence of regional smoke haze episodes due to biomass burning in Indonesia. Among the POCs investigated, phthalic acid and cis-pinonic acid showed a strong linear relationship with maximum daily ozone concentration, indicating secondary organic aerosols (SOA to be an important contributor to ambient atmospheric organics over Singapore.

  10. Pyrosequencing reveals the influence of elevated atmospheric CO2 on the composition of archaeal communities in the rhizosphere of C3 and C4 crops

    Science.gov (United States)

    Nelson, D. M.; Cann, I. K.; Mackie, R. I.

    2008-12-01

    The projected increase in atmospheric CO2 concentrations throughout the 21st century is likely to increase aboveground and belowground plant productivity and cause changes in the quantity and quality of plant root exudates, although plants using C4 photosynthesis are likely to be only affected during times of drought (Leakey et al., 2006, Plant Physiology, 140, 779). Evidence is emerging from molecular tools that these changes may influence the abundance and composition of soil microbial communities that regulate key soil processes, such as nitrogen cycling (Lesaulnier et al., 2008, Environmental Microbiology, 10, 926). However, most molecular tools are not well-suited for comparing multiple samples at great sequencing depth, which is critical when considering soil microbial communities of high diversity. To overcome these limitations we used pyrosequencing and quantitative PCR (qPCR) of two genes (the V3 region of 16S rDNA and the amoA gene) to examine intra- and inter-treatment variability in the abundance and composition of microbial communities in the rhizosphere of soybean (C3) and maize (C4) grown in field conditions under ambient (~380 ppm) and elevated (~550 ppm) CO2 using FACE (free-air concentration enrichment) technology during the 2006 growing season in central Illinois. We specifically focused on archaeal communities because of their key role in nitrification (Leininger et al., 2006, Nature, 442, 806). The majority (>97%) of recovered sequences were from members of the phylum Crenarchaeota. Principle component analysis of sequence results from the V3 and amoA genes indicated significant (p<0.05) differences in the composition of rhizosphere archaeal communities between ambient and elevated CO2 beneath soybean, but not maize. qPCR suggested no significant difference in the abundance of archaea between treatments for soybean and maize. The lack of response of archaeal community composition beneath maize to elevated CO2 is consistent with relatively high

  11. Contributions of the Atmospheric Radiation Measurement (ARM) Program and the ARM Climate Research Facility to the U.S. Climate Change Science Program

    Energy Technology Data Exchange (ETDEWEB)

    SA Edgerton; LR Roeder

    2008-09-30

    The Earth’s surface temperature is determined by the balance between incoming solar radiation and thermal (or infrared) radiation emitted by the Earth back to space. Changes in atmospheric composition, including greenhouse gases, clouds, and aerosols can alter this balance and produce significant climate change. Global climate models (GCMs) are the primary tool for quantifying future climate change; however, there remain significant uncertainties in the GCM treatment of clouds, aerosol, and their effects on the Earth’s energy balance. The 2007 assessment (AR4) by the Intergovernmental Panel on Climate Change (IPCC) reports a substantial range among GCMs in climate sensitivity to greenhouse gas emissions. The largest contributor to this range lies in how different models handle changes in the way clouds absorb or reflect radiative energy in a changing climate (Solomon et al. 2007). In 1989, the U.S. Department of Energy (DOE) Office of Science created the Atmospheric Radiation Measurement (ARM) Program within the Office of Biological and Environmental Research (BER) to address scientific uncertainties related to global climate change, with a specific focus on the crucial role of clouds and their influence on the transfer of radiation in the atmosphere. To address this problem, BER has adopted a unique two-pronged approach: * The ARM Climate Research Facility (ACRF), a scientific user facility for obtaining long-term measurements of radiative fluxes, cloud and aerosol properties, and related atmospheric characteristics in diverse climate regimes. * The ARM Science Program, focused on the analysis of ACRF data to address climate science issues associated with clouds, aerosols, and radiation, and to improve GCMs. This report describes accomplishments of the BER ARM Program toward addressing the primary uncertainties related to climate change prediction as identified by the IPCC.

  12. Atmospheric Correction Performance of Hyperspectral Airborne Imagery over a Small Eutrophic Lake under Changing Cloud Cover

    Directory of Open Access Journals (Sweden)

    Lauri Markelin

    2016-12-01

    Full Text Available Atmospheric correction of remotely sensed imagery of inland water bodies is essential to interpret water-leaving radiance signals and for the accurate retrieval of water quality variables. Atmospheric correction is particularly challenging over inhomogeneous water bodies surrounded by comparatively bright land surface. We present results of AisaFENIX airborne hyperspectral imagery collected over a small inland water body under changing cloud cover, presenting challenging but common conditions for atmospheric correction. This is the first evaluation of the performance of the FENIX sensor over water bodies. ATCOR4, which is not specifically designed for atmospheric correction over water and does not make any assumptions on water type, was used to obtain atmospherically corrected reflectance values, which were compared to in situ water-leaving reflectance collected at six stations. Three different atmospheric correction strategies in ATCOR4 was tested. The strategy using fully image-derived and spatially varying atmospheric parameters produced a reflectance accuracy of ±0.002, i.e., a difference of less than 15% compared to the in situ reference reflectance. Amplitude and shape of the remotely sensed reflectance spectra were in general accordance with the in situ data. The spectral angle was better than 4.1° for the best cases, in the spectral range of 450–750 nm. The retrieval of chlorophyll-a (Chl-a concentration using a popular semi-analytical band ratio algorithm for turbid inland waters gave an accuracy of ~16% or 4.4 mg/m3 compared to retrieval of Chl-a from reflectance measured in situ. Using fixed ATCOR4 processing parameters for whole images improved Chl-a retrieval results from ~6 mg/m3 difference to reference to approximately 2 mg/m3. We conclude that the AisaFENIX sensor, in combination with ATCOR4 in image-driven parametrization, can be successfully used for inland water quality observations. This implies that the need for in situ

  13. Quantifying atmospheric nitrate formation pathways based on a global model of the oxygen isotopic composition (Δ17O of atmospheric nitrate

    Directory of Open Access Journals (Sweden)

    J. A. Thornton

    2009-05-01

    Full Text Available The oxygen isotopic composition (Δ17O of atmospheric nitrate is a function of the relative abundance of atmospheric oxidants (O3, HOx=OH +HO2+RO2 and the formation pathway of nitrate from its precursor NOx (=NO+NO2. Coupled observations and modeling of nitrate Δ17O can be used to quantify the relative importance of chemical formation pathways leading to nitrate formation and reduce uncertainties in the budget of reactive nitrogen chemistry in the atmosphere. We present the first global model of atmospheric nitrate Δ17O and compare with available observations. The model shows the best agreement with a global compilation of observations when assuming a Δ17O value of tropospheric ozone equal to 35‰ and preferential oxidation of NOx by the terminal oxygen atoms of ozone. Calculated values of annual-mean nitrate Δ17O in the lowest model layer (0–200 m above the surface vary from 6‰ in the tropics to 41‰ in the polar-regions. On the global scale, O3 is the dominant oxidant (81% annual-mean during NOx cycling reactions. The global, annual-mean tropospheric inorganic nitrate burden is dominated by nitrate formation via NO2+OH (76%, followed by N2O5 hydrolysis (18% and NO3+DMS/HC (4%. Model discrepancies are largest in the polar spring and summer, most likely due to the lack of reactive halogen chemistry in the model. The influence of organic nitrates on observations of nitrate Δ17O needs to be determined, especially for observations in summertime and tropical forested regions where organic nitrates can contribute up to 80% of the total NOy (organic plus inorganic nitrate budget.

  14. Occultation observations of atmosphere and climate change from space: a backbone for the GCOS

    Science.gov (United States)

    Kirchengast, G.

    2003-04-01

    Since the early use of the occultation measurement principle for sounding planetary atmospheres, its exploitation has seen tremendous advances. A particular boost was felt since the late eighties when a variety of intriguing opportunities for application to the atmosphere of our home planet Earth were increasingly recognized, such as utilizing new signal sources like Global Navigation Satellite System (GNSS) signals. Today we use and plan occultation sensors on Low Earth Orbit (LEO) satellites, which exploit solar, lunar, stellar, GNSS, and LEO-crosslink signals. The sensors, together, smartly utilize the whole electromagnetic spectrum from EUV/UV via VIS/IR and MW to Radio and exploit all kinds of atmosphere-radiation interaction such as absorption and scattering, both by molecules and aerosols, as well as refraction. The parameters obtained, from the Earth's surface up through the entire atmosphere, extend from the fundamental mass field variables temperature, pressure, and geopotential height via the fundamental variable trace gases water vapor and ozone (and many further important trace species) to key particulate species such as aerosols and cloud liquid water. All these measurements rest on one and the same occultation principle with its unique properties of providing self-calibration, high accuracy and vertical resolution, global coverage, and (if using radio signals) all-weather capability. Occultation data thus bear enormous utility for applications in climate monitoring and research but also in other fields such as numerical weather prediction and atmospheric physics and chemistry. The self-calibration property is particularly crucial for climate change monitoring, as it enables unique long-term stability in climate datasets. The latter can be built from occultation data of different satellites and times without inter-calibration efforts. In fact, a controversy such as the recent one on the tropospheric temperature record over the last two decades

  15. Bioenergy from forestry and changes in atmospheric CO2: reconciling single stand and landscape level approaches.

    Science.gov (United States)

    Cherubini, Francesco; Guest, Geoffrey; Strømman, Anders H

    2013-11-15

    Analyses of global warming impacts from forest bioenergy systems are usually conducted either at a single stand level or at a landscape level, yielding findings that are sometimes interpreted as contrasting. In this paper, we investigate and reconcile the scales at which environmental impact analyses of forest bioenergy systems are undertaken. Focusing on the changes caused in atmospheric CO2 concentration of forest bioenergy systems characterized by different initial states of the forest, we show the features of the analyses at different scales and depict the connections between them. Impacts on atmospheric CO2 concentration at a single stand level are computed through impulse response functions (IRF). Results at a landscape level are elaborated through direct application of IRFs to the emission profile, so to account for the fluxes from all the stands across time and space. Impacts from fossil CO2 emissions are used as a benchmark. At a landscape level, forest bioenergy causes an increase in atmospheric CO2 concentration for the first decades that is similar to the impact from fossil CO2, but then the dynamics clearly diverge because while the impact from fossil CO2 continues to rise that from bioenergy stabilizes at a certain level. These results perfectly align with those obtained at a single stand for which characterization factors have been developed. In the hypothetical case of a sudden cessation of emissions, the change caused in atmospheric CO2 concentration from biogenic CO2 emissions reverses within a couple of decades, while that caused by fossil CO2 emissions remains considerably higher for centuries. When counterfactual aspects like the additional sequestration that would have occurred in the forest if not harvested and the theoretical displacement of fossil CO2 are included in the analysis, results can widely differ, as the CO2 debt at a landscape level ranges from a few years to several centuries (depending on the underlying assumptions considered).

  16. Productivity changes in the Mediterranean Sea for the 21st century in response to changes in the regional atmospheric forcing

    Directory of Open Access Journals (Sweden)

    Diego M Macias

    2015-10-01

    Full Text Available The Mediterranean Sea is considered as a hotspot for climate change because of its location in the temperate region and because it is a semi-enclosed basin surrounded by highly populated and developed countries. Some expected changes include an increase in air temperature and changes in the periodicity and spatial distribution of rainfall. Alongside, demographic and politics changes will alter freshwater quantity and quality. All these changes will have an impact on the ecological status of marine ecosystems in the basin. We use a 3D hydrodynamic-biogeochemical coupled model of the entire Mediterranean Sea to explore potential changes in primary productivity (mean values and spatial distribution under two emission scenarios (rcp4.5 and rcp8.5.To isolate the effects of changes in atmospheric conditions alone, in this ensemble of simulations rivers conditions (water flow and nutrient concentrations are kept unchanged and equal to its climatological values for the last 10 years. Despite the significant warming trend, the mean integrated primary production rate in the entire basin remains almost unchanged. However characteristic spatial differences are consistently found in the different simulations. The western basin becomes more oligotrophic associated to a surface density decrease (increase stratification because of the influence of the Atlantic waters which prevents surface salinity to increase. In the eastern basin, on the contrary, all model runs simulates an increase in surface production linked to a density increase (less stratification because of the increasing evaporation rate. The simulations presented here demonstrate the basic response patterns of the Mediterranean Sea ecosystem to changing climatological conditions. Although unlikely, they could be considered as a ‘baseline’ of expected consequences of climatic changes on marine conditions in the Mediterranean.

  17. Projected changes in atmospheric heating due to changes in fire disturbance and the snow season in the western Arctic, 2003–2100

    Science.gov (United States)

    Euskirchen, E.S.; McGuire, Anthony; Rupp, T.S.; Chapin, F. S.; Walsh, J.E.

    2009-01-01

    In high latitudes, changes in climate impact fire regimes and snow cover duration, altering the surface albedo and the heating of the regional atmosphere. In the western Arctic, under four scenarios of future climate change and future fire regimes (2003–2100), we examined changes in surface albedo and the related changes in regional atmospheric heating due to: (1) vegetation changes following a changing fire regime, and (2) changes in snow cover duration. We used a spatially explicit dynamic vegetation model (Alaskan Frame-based Ecosystem Code) to simulate changes in successional dynamics associated with fire under the future climate scenarios, and the Terrestrial Ecosystem Model to simulate changes in snow cover. Changes in summer heating due to the changes in the forest stand age distributions under future fire regimes showed a slight cooling effect due to increases in summer albedo (mean across climates of −0.9 W m−2 decade−1). Over this same time period, decreases in snow cover (mean reduction in the snow season of 4.5 d decade−1) caused a reduction in albedo, and a heating effect (mean across climates of 4.3 W m−2 decade−1). Adding both the summer negative change in atmospheric heating due to changes in fire regimes to the positive changes in atmospheric heating due to changes in the length of the snow season resulted in a 3.4 W m−2 decade−1 increase in atmospheric heating. These findings highlight the importance of gaining a better understanding of the influences of changes in surface albedo on atmospheric heating due to both changes in the fire regime and changes in snow cover duration.

  18. Effect of cold atmospheric pressure He-plasma jet on DNA change and mutation

    Science.gov (United States)

    Yaopromsiri, C.; Yu, L. D.; Sarapirom, S.; Thopan, P.; Boonyawan, D.

    2015-12-01

    Cold atmospheric pressure plasma jet (CAPPJ) effect on DNA change was studied for assessment of its safety. The experiment utilized a home-developed CAPPJ using 100% helium to directly treat naked DNA plasmid pGFP (plasmid green fluorescent protein). A traversal electric field was applied to separate the plasma components and both dry and wet sample conditions were adopted to investigate various factor roles in changing DNA. Plasma species were measured by using optical emission spectroscopy. DNA topological form change was analyzed by gel electrophoresis. The plasma jet treated DNA was transferred into bacterial Escherichia coli cells for observing mutation. The results show that the He-CAPPJ could break DNA strands due to actions from charge, radicals and neutrals and potentially cause genetic modification of living cells.

  19. Effect of cold atmospheric pressure He-plasma jet on DNA change and mutation

    Energy Technology Data Exchange (ETDEWEB)

    Yaopromsiri, C. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Yu, L.D., E-mail: yuld@thep-center.org [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Sarapirom, S. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Faculty of Science, Maejo University, Bang Khen, Chiang Mai 50290 (Thailand); Thopan, P.; Boonyawan, D. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2015-12-15

    Cold atmospheric pressure plasma jet (CAPPJ) effect on DNA change was studied for assessment of its safety. The experiment utilized a home-developed CAPPJ using 100% helium to directly treat naked DNA plasmid pGFP (plasmid green fluorescent protein). A traversal electric field was applied to separate the plasma components and both dry and wet sample conditions were adopted to investigate various factor roles in changing DNA. Plasma species were measured by using optical emission spectroscopy. DNA topological form change was analyzed by gel electrophoresis. The plasma jet treated DNA was transferred into bacterial Escherichia coli cells for observing mutation. The results show that the He-CAPPJ could break DNA strands due to actions from charge, radicals and neutrals and potentially cause genetic modification of living cells.

  20. Does the trigger for abrupt climate change reside in the ocean or in the atmosphere?

    Science.gov (United States)

    Broecker, W S

    2003-06-06

    Two hypotheses have been put forward to explain the large and abrupt climate changes that punctuated glacial time. One attributes such changes to reorganizations of the ocean's thermohaline circulation and the other to changes in tropical atmosphere-ocean dynamics. In an attempt to distinguish between these hypotheses, two lines of evidence are examined. The first involves the timing of the freshwater injections to the northern Atlantic that have been suggested as triggers for the global impacts associated with the Younger Dryas and Heinrich events. The second has to do with evidence for precursory events associated with the Heinrich ice-rafted debris layers in the northern Atlantic and with the abrupt Dansgaard-Oeschger warmings recorded in the Santa Barbara Basin.

  1. Sintering behavior of Cr in diff erent atmospheres and its eff ect on the microstructure and properties of copper-based composite materials

    Institute of Scientific and Technical Information of China (English)

    Ye Wang; Qing-zhi Yan; Fei-fei Zhang; Chang-chun Ge; Xiao-lu Zhang; Hai-qin Zhao

    2013-01-01

    Copper matrix composites consisting of chromium (Cr) or ferrochrome (Cr-Fe) as strengthening elements and molybdenum disulfide as a lubricant had been sintered in nitrogen and hydrogen atmosphere, respectively. Their morphology and energy-dispersive X-ray spectrometry (EDS) analysis showed that serious interaction occurred between MoS2 and Cr (or Cr-Fe) particles when the samples were sintered in hydrogen atmosphere. Chromium sulfide compound (CrxSy) was formed as a reaction product, which decreased the density and strength of the composites remarkably. This interaction was inhibited when the samples were sintered in nitrogen atmosphere; thus, the mechanical properties of the composites were improved.

  2. The impact of global aviation NOx emissions on tropospheric composition changes from 2005 to 2011

    Science.gov (United States)

    Wasiuk, D. K.; Khan, M. A. H.; Shallcross, D. E.; Lowenberg, M. H.

    2016-09-01

    The impact of aviation NOx emissions from 2005 to 2011 on the chemical composition of the atmosphere has been investigated on the basis of integrations of the 3-D global chemical and transport model, STOCHEM-CRI with the novel CRIv2-R5 chemistry scheme. A base case simulation without aircraft NOx emissions and integrations with NOx emissions from aircraft are inter-compared. The sensitivity of the global atmosphere to varying the quantity and the geographical distribution of the global annual aviation NOx emissions is assessed by performing, for the first time, a series of integrations based on changing the total mass and distribution of aircraft NOx emissions derived from air traffic movements recorded between 2005 and 2011. The emissions of NOx from the global fleet based on actual records of air traffic movements between 2005 and 2011 increased the global tropospheric annual mean burden of O3 by 1.0 Tg and decreased the global tropospheric annual mean burden of CH4 by 2.5 Tg. The net NOy and O3 production increases by 0.5% and 1%, respectively between 2005 and 2011 in total. At cruise altitude, the absolute increase in the modelled O3 mixing ratios is found to be up to 0.7 ppb between 2005 and 2011 at 25°N-50°N.

  3. Australian atmospheric lead deposition reconstructed using lead concentrations and isotopic compositions of archival lichen and fungi.

    Science.gov (United States)

    Wu, Liqin; Taylor, Mark Patrick; Handley, Heather K; Wu, Michael

    2016-01-01

    Lead concentrations and their isotopic compositions were measured in lichen genera Cladonia and Usnea and fungi genus Trametes from the Greater Sydney region (New South Wales, Australia) that had been collected and archived over the past 120 years. The median lead contents were elevated in lichens and fungi prior to the introduction of leaded petrol (Cladonia 12.5 mg/kg; Usnea 15.6 mg/kg; Trametes 1.85 mg/kg) corresponding to early industrial development. During the use of leaded petrol for automobiles in Australia from 1932 to 2002, total median lead concentrations rose: Cladonia 18.8 mg/kg; Usnea 21.5 mg/kg; Trametes 4.3 mg/kg. Following the cessation of leaded petrol use, median total lead concentrations decreased sharply in the 2000s: Cladonia 4.8 mg/kg; Usnea 1.7 mg/kg. The lichen and fungi isotopic compositions reveal a significant decrease in (206)Pb/(207)Pb values from the end of 19th century to the 1970s. The following decades were characterised by lower allowable levels of lead additive in fuel and the introduction of unleaded petrol in 1985. The environmental response to these regulatory changes was that lichen and fungi (206)Pb/(207)Pb values increased, particularly from 1995 onwards. Although the lead isotope ratios of lichens continued to increase in the 2000s they do not return to pre-leaded petrol values. This demonstrates that historic leaded petrol emissions, inter alia other sources, remain a persistent source of anthropogenic contamination in the Greater Sydney region.

  4. Changes occurring in vegetable oils composition due to microwave heating

    Directory of Open Access Journals (Sweden)

    Hassan El-Mallah, M.

    2003-12-01

    Full Text Available The effect of microwave heating on three vegetable oils having different lipid compositions was studied. Sunflower, soybean and peanut oils in comparison with oil admixture of soybean and peanut oil (1:1, w/w, were selected for this study. Each oil was heated for 2, 4, 6, 8, 10, 12, 15 and 18 minutes in microwave oven. Peroxide value, free acidity and colour absorbance (at 420 nm were proportionally increasing with the increase of heating period. Colour absorption threw light on the formation of browning products arising from phospholipids during microwave heating. Total tocopherol contents were determined by preparative thin layer chromatography, whereas the fatty acid compositions and formed epoxy acid were analyzed by capillary gas liquid chromatography. The formed conjugated dienes and trienes were determined by UV spectrophotometry. It was found that the total tocopherols of the microwave heated oils, decreased depending on the type of the predominating tocopherols. Also a relation of peroxide formation, during microwave heating, with changes in total tocopherol composition was discussed. It was found that polyunsaturated fatty acids generally decreased by increasing the heating period. The results obtained from the heated oil admixture helped interpret the results obtained from other heated individual oils.Se estudia el efecto del calentamiento en horno de microondas sobre aceites de diferente composición en ácidos grasos. Aceites de girasol, soja, cacahuete y una mezcla de soja y cacahuete al 50%, se calentaron durante 2, 4, 6, 8 10, 12, 15 y 18 minutos. Los valores de índice de peróxidos, acidez libre y absorbancia a 420 nm fueron proporcionales al tiempo de calentamiento. Otras determinaciones incluyeron el contenido total en tocoferoles mediante cromatografía en capa fina, la composición en ácidos grasos y en epoxiácidos mediante cromatografía gas líquido, y la formación de dienos y trienos conjugados mediante

  5. Changes in precipitation extremes projected by a 20-km mesh global atmospheric model

    Directory of Open Access Journals (Sweden)

    Akio Kitoh

    2016-03-01

    Full Text Available High-resolution modeling is necessary to project weather and climate extremes and their future changes under global warming. A global high-resolution atmospheric general circulation model with grid size about 20 km is able to reproduce climate fields as well as regional-scale phenomena such as monsoonal rainfall, tropical and extratropical cyclones, and heavy precipitation. This 20-km mesh model is applied to project future changes in weather and climate extremes at the end of the 21st century with four different spatial patterns in sea surface temperature (SST changes: one with the mean SST changes by the 28 models of the Coupled Model Intercomparison Project Phase 5 (CMIP5 under the Representative Concentration Pathways (RCP-8.5 scenario, and the other three obtained from a cluster analysis, in which tropical SST anomalies derived from the 28 CMIP5 models were grouped. Here we focus on future changes in regional precipitation and its extremes. Various precipitation indices averaged over the Twenty-two regional land domains are calculated. Heavy precipitation indices (maximum 5-day precipitation total and maximum 1-day precipitation total increase in all regional domains, even where mean precipitation decrease (Southern Africa, South Europe/Mediterranean, Central America. South Asia is the domain of the largest extreme precipitation increase. In some domains, different SST patterns result in large precipitation changes, possibly related to changes in large-scale circulations in the tropical Pacific.

  6. Non-thermal Atmospheric Plasma Treatment for Deactivation of Oral Bacteria and Improvement of Dental Composite Restoration

    Science.gov (United States)

    Yu, Qing Song; Li, H.; Ritts, A. C.; Yang, B.; Chen, M.; Hong, L.; Xu, C.; Yao, X.; Wang, Y.

    This paper reviews our recent research results of using non-thermal ­atmospheric plasmas for oral bacterial deactivation and for composite restoration improvement. Oral bacteria of Streptococcus mutans (S. mutans) and Lactobacillus acidophilus (L. acidophilus) with an initial bacterial population density between 1.0 × 108 and 5.0 × 108 cfu/ml were seeded on various media and their survivability with plasma exposure was examined. The plasma exposure time for a 99.9999% cell reduction was less than 15 s for S. mutans and within 5 min for L. acidophilus. To evaluate the dentin/composite interfacial bonding, extracted unerupted human third molars were used by removing the crowns and etching the exposed dentin surfaces with 35% phosphoric acid gel. After dental composite application and light curing, the teeth were then sectioned into micro-bars as the specimens for microtensile test. Student Newman Keuls (SNK) tests showed that the bonding strength of the composite restoration to peripheral dentin was significantly increased (by 64%) after 30 s plasma treatment of the dentin surfaces. These findings indicated that non-thermal atmospheric plasma technology is very promising for dental clinical applications.

  7. Warming-Induced Changes to the Molecular Composition of Soil Organic Matter

    Science.gov (United States)

    Feng, X.; Simpson, M. J.; Simpson, A. J.; Wilson, K. P.; Williams, D.

    2007-12-01

    Soil organic matter (SOM) contains two times more carbon than the atmosphere and the potential changes to SOM quantity and quality with global warming are a major concern. It is commonly believed that global warming will accelerate the decomposition of labile SOM compounds while refractory SOM constituents will remain stable. However, experimental evidence of molecular-level changes to SOM composition with global warming is currently lacking. Here we employ SOM biomarkers and nuclear magnetic resonance (NMR) spectroscopy to study SOM composition and degradation in a soil warming experiment in southern Ontario, Canada. The soil warming experiment consisted of a control and a treatment plot in a mixed forest that had a temperature difference of about 5 degrees C for 14 months. Before soil warming the control and treatment plots had the same organic carbon (OC) content and SOM composition. Soil warming significantly increased soil OC content and the abundance of cutin-derived carbon originating from leaf tissues and decreased carbohydrates that are regarded as easily degradable. Lignin components, which are believed to be part of the stable and slowly-cycling SOM, were observed to be in an advanced stage of degradation. This observation is corroborated by increases in fungal biomass in the warmed soil because fungi are considered the primary decomposer of lignin in the soil environment. An NMR study of SOM in the warmed and control plots indicates that alkyl carbon, mainly originating from plant cuticles in the soil, increased in the warmed soil while O-alkyl carbon, primarily occurring in carbohydrates, decreased. Aromatic and phenolic carbon regions, which include the main structures found in lignin, decreased in the warmed soil. These data collectively suggest that there is a great potential for lignin degradation with soil warming, and that the refractory (aromatic) soil carbon storage may be reduced as a result of increased fungal growth in a warmer climate.

  8. Glacial-interglacial water cycle, global monsoon and atmospheric methane changes

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Zhengtang; Wu, Haibin [Chinese Academy of Sciences, Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Beijing (China); Zhou, Xin [Chinese Academy of Sciences, Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Beijing (China); University of Science and Technology of China, School of Earth and Space Sciences and Institute of Polar Environment, Hefei (China)

    2012-09-15

    The causes of atmospheric methane (CH{sub 4}) changes are still a major contention, in particular with regards to the relative contributions of glacial-interglacial cycles, monsoons in both hemispheres and the late Holocene human intervention. Here, we explore the CH{sub 4} signals in the Antarctic EPICA Dome C and Vostok ice records using the methods of timeseries analyses and correlate them with insolation and geological records to address these issues. The results parse out three distinct groups of CH{sub 4} signals attributable to different drivers. The first group ({proportional_to}80% variance), well tracking the marine {delta}{sup 18}O record, is attributable to glacial-interglacial modulation on the global water cycle with the effects shared by wetlands at all latitudes, from monsoonal and non-monsoonal regions in both hemispheres. The second group ({proportional_to}15% variance), centered at the {proportional_to}10-kyr semi-precession frequency, is linkable with insolation-driven tropical monsoon changes in both hemispheres. The third group ({proportional_to}5% variance), marked by millennial frequencies, is seemingly related with the combined effect of ice-volume and bi-hemispheric insolation changes at the precession bands. These results indicate that bi-hemispheric monsoon changes have been a constant driver of atmospheric CH{sub 4}. This mechanism also partially explains the Holocene CH{sub 4} reversal since {proportional_to}5 kyr BP besides the human intervention. In the light of these results, we propose that global monsoon can be regarded as a system consisting of two main integrated components, one primarily driven by the oscillations of Inter-Tropical Convergence Zone (ITCZ) in response to the low-latitude summer insolation changes, anti-phase between the two hemispheres (i.e. the ITCZ monsoon component); and another modulated by the glacial-interglacial cycles, mostly synchronous at the global scale (i.e. the glacial-interglacial monsoon

  9. Regional climate extremes in Northern Eurasia associated with atmospheric blockings: Interannual variations and tendencies of change

    Science.gov (United States)

    Mokhov, I.; Akperov, M.; Lupo, A. R.; Chernokulsky, A. V.; Timazhev, A.

    2011-12-01

    Large regional climate anomalies associated with atmospheric blockings have been noted during last years in Northern Eurasia. Impact of blockings is exhibited in such extremes as heat and cold waves, droughts, and forest fires. In order to detect changes in the blocking activity characteristics an analysis of different data for the Northern Hemisphere with the use of various methods for blockings detection was carried out. In particular, the data for 500 hPa geopotential from the NCEP/NCAR Reanalysis 1 (1948-2010) and NOAA-CIRES 20th Century Reanalysis v2 (1871-2008) have been used as well as climate model simulations for the 20th and 21st centuries with anthropogenic forcing. Special attention is paid to the analysis of extreme dry conditions in the Northern Eurasia regions and to the 2010 Russian heat wave associated to atmospheric blockings with the use observational data (1891-2010) for surface air temperature, precipitation and different indices for the drought conditions. Tendencies of change and interannual variations are analyzed with an assessment of effects of El-Nino/La-Nina phenomena. Possibility of intensification of blocking-associated climate impacts under global warming is discussed. Changes of blocking characteristics and associated regional climate anomalies in the 21st century based on model simulations with anthropogenic scenarios are analyzed.

  10. Atmospheric winter response to Arctic sea ice changes in reanalysis data and model simulations

    Science.gov (United States)

    Jaiser, Ralf; Nakamura, Tetsu; Handorf, Dörthe; Dethloff, Klaus; Ukita, Jinro; Yamazaki, Koji

    2016-07-01

    The changes of atmospheric flow patterns related to Arctic Amplification have impacts well beyond the Arctic regional weather and climate system. Here we examine modulations of vertically propagating planetary waves, a major feature of the climate response to Arctic sea ice reduction by comparing the corresponding results of an atmospheric general circulation model with reanalysis data for periods of high and low sea ice conditions. Under low sea ice condition we find enhanced coupling between troposphere and stratosphere starting in November with preferred polar stratospheric vortex breakdowns in February, which then feeds back to the troposphere. The model experiment and ERA-Interim reanalysis data agree well with respect to temporal and spatial characteristics associated with vertical planetary wave propagation including its precursors. The upward propagating planetary wave anomalies resemble a wave number 1 and 2 pattern depending on region and timing. Since our experimental design only allows influences from sea ice changes and there is a high degree of resemblance between model results and observations, we conclude that sea ice is a main driver of observed winter circulation changes.

  11. Changes in proximate composition and oil characteristics during flaxseed development

    Directory of Open Access Journals (Sweden)

    Herchi, W.

    2014-06-01

    Full Text Available Atmospheric Pressure Photoionization-Mass Spectrometry (APPI-MS and High Performance Liquid Chromatography (HPLC are the two analytical methods that were used to characterize Triacylglycerols (TAGs during flaxseed development. The HPLC method of the oils showed the presence of 15 TAG species. In contrast to the HPLC chromatograms, the APPI-MS showed 17 peaks of TAG. APPI-MS is more rapid than the HPLC method (11 min. The iodine value of the oils showed a gradual increase, while the oil stability continuously decreased. Proximate composition during flaxseed development revealed that flaxseed is potentially a good source of dietary energy and protein. At full maturity, flaxseed contained 37% oil and 24% protein on a dry-weight basis; albumin was the major storage protein (53% of total storage proteins followed by globulin (33% and glutelin fractions (11%. Prolamins had the lowest percentage with 3%. α-amylase activity was higher in the mature seeds than the young ones.Fotoionización a presión atmosférica-Espectrometría de masas (APPI-MS y cromatografía líquida de alta resolución (HPLC son dos métodos de análisis que se utilizaron para caracterizar triglicéridos (TAGs durante el desarrollo de semillas de linaza. El método HPLC mostró la presencia de 15 especies de TAG, en contraste, los cromatogramas de APPI-MS mostraron 17 picos de TAG siendo el método APPI-MS más rápido que el de HPLC (11 min. El índice de yodo de los aceites mostró un aumento gradual, mientras que la estabilidad disminuyó continuamente. El estudio de la composición proximal de la linaza durante su desarrollo, mostró que esta semilla es una fuente potencialmente buena de energía y de proteína para la dieta. Al final de la maduración, la linaza contenía 37 % de aceite y 24 % de proteína sobre peso seco; albúmina fue la principal proteína de almacenamiento (53% sobre el total de las proteínas de almacenamiento seguido de la globulina (33 % y glutelina

  12. The chemical composition and fluxes of atmospheric wet deposition at four sites in South Africa

    Science.gov (United States)

    Conradie, E. H.; Van Zyl, P. G.; Pienaar, J. J.; Beukes, J. P.; Galy-Lacaux, C.; Venter, A. D.; Mkhatshwa, G. V.

    2016-12-01

    South Africa is the economic hub of southern Africa and is regarded as an important source region of atmospheric pollutants. A nitrogen dioxide (NO2) hotspot is clearly visible from space over the South African Mpumalanga Highveld, while South Africa is also regarded as the 9th largest anthropogenic sulphur (S) emitting country. Notwithstanding the importance of South Africa with regard to nitrogen (N) and S emissions, very limited data has been published on the chemical composition of wet deposition for this region. This paper presents the concentrations of sodium (Na+), ammonium (NH4+), potassium (K+), calcium (Ca2+), magnesium (Mg2+), nitrate (NO3-), chloride (Cl-), sulphate (SO42-) and water-soluble organic acids (OA) in the wet deposition samples collected between 2009 and 2014 at four South African IDAF (IGAC DEBITS Africa) sites, which are regarded as regional representatives of the north-eastern interior. Also, wet deposition fluxes of the ten ions are calculated and presented in this paper. The results show that the total ionic concentrations and fluxes of wet deposition were much higher at the two sites closer to anthropogenic emissions, while the pH of wet deposition at these two sites were lower compared to that of the two sites that were less impacted by anthropogenic emissions. . The major sources of the ten ions included marine, terrigenous (crust), fossil fuel combustion, agriculture and biomass burning. Significant contributions from fossil fuel combustion were determined for the two sites in close proximity to anthropogenic source regions. The results of back trajectory analysis, however, did indicate that the two remote sites are also affected by air masses passing over the source region through anti-cyclonic recirculation. The largest contributions at the two sites distant from the anthropogenic source regions were marine sources, while the impact of biomass burning was also more significant at the remote sites. Comparison to previous wet

  13. Titan's atmosphere from ISO observations: Temperature, composition and detection of water vapor

    Science.gov (United States)

    Coustenis, A.; Salama, A.; Lellouch, E.; Encrenaz, Th.; de Graauw, Th.; Bjoraker, G. L.; Samuelson, R. E.; Gautier, D.; Feuchtgruber, H.; Kessler, M. F.; Orton, G. S.

    1998-09-01

    Observations of Titan in the thermal infrared (2.36-45.2 mu m) were performed by ISO, in Jan. and Dec. 1997, with resolving powers between 1500 and 3000 in the Grating mode and up to 30000 in the Fabry-Perot mode. Two pure rotational water lines were observed using the ISO/SWS/Grating (R=2000) at 39.4 and 43.9 mu m, with fluxes of about 2 Jy over a continuum of 60 Jy [1], with S/N ~ 8. The flux observed can be reproduced with a constant abundance of ~ 4 x 10(-10) , or with a recent photochemical profile [2] multiplied by a factor of 0.4. This yields a H_2O vapor mole fraction of about 10(-8) at the 400 km altitude level (column density of 2.5 x 10(14) mol cm(-2) ). The inferred water influx at Titan at 700 km of altitude is : (0.8-2.8) x 10(6) mol cm(-2) s(-1) , compatible with the CO2 observed abundance and similar to that found at Saturn [3]. This suggests that infalling material from Saturn rings may not be the dominant source of Saturn's water. The analysis of the 233-1500 cm(-1) spectrum of ISO/SWS has provided the thermal and compositional structure of Titan on a disk-average [4]. In particular, observations of the CH_3D band at 1150 cm(-1) significantly improved the determination of the D/H ratio in Titan's stratosphere. The new value of 7.5 x 10(-5) , is four times lower than in comets and suggests that Titan's atmosphere is not of cometary origin, but rather formed by outgassing from the interior. We have also tested available vertical profiles and inferred upper limits for a few likely candidates in Titan's stratosphere (such as benzene and allene) [4]. References [1] COUSTENIS, A., et al. 1998a. Astron. Astrophys. 336, L85. [2] LARA, L. M., et al. 1996. J. Geophys. Res.-Planets 101, 23261-23283. [3] FEUCHTGRUBER, H., et al. 1997. Nature 389, 159-162. [4] COUSTENIS, A., et al. 1998b. Submitted for publication.

  14. Fog composition at Baengnyeong Island in the Eastern Yellow Sea: detecting markers of aqueous atmospheric oxidations

    Directory of Open Access Journals (Sweden)

    A. J. Boris

    2015-09-01

    Full Text Available Samples of fog water were collected at Baengnyeong Island (BYI in the Yellow Sea during the summer of 2014. The most abundant chemical species in the fog water were NH4+ (mean of 2220 μM, NO3− (1260 μM, SO4−2 (730 μM, and Na+ (551 μM, with substantial contributions from other ions consistent with marine and biomass burning influence on some dates. The pH of the samples ranged between 3.48 and 5.00, with a mean of 3.94, intermediate within pH values of fog/cloud water reported previously in Southeast Asia. Back trajectories (72 h showed that high relative humidity (> 80 % was encountered upwind of the sampling site by all but one of the sampled air masses, and that the fog composition at BYI can be impacted by several different source regions, including the Sea of Japan, Northeastern China, and the East China Sea. Sulfur in the collected fog was highly oxidized: low S(IV concentrations were measured (mean of 2.36 μM in contrast to SO4−2 and in contrast to fog/cloud S(IV concentrations from pollutant source regions; organosulfate species were also observed and were most likely formed through aging of mainly biogenic volatile organic compounds. Low molecular mass organic acids were major contributors to total organic carbon (TOC; 36–69 %, comprising a fraction of TOC at the upper end of that seen in fogs and clouds in other polluted environments. Large contributions were observed from not only acetic and formic acids, but also oxalic, succinic, maleic, and other organic acids that can be produced in aqueous atmospheric organic processing (AAOP reactions. These samples of East Asian fog water containing highly oxidized components represent fog downwind of pollutant sources and can provide new insight into the fate of regional emissions. In particular, these samples demonstrate the result of extensive photochemical aging during multiday transport, including oxidation within wet aerosols and fogs.

  15. Characteristics and composition of atmospheric aerosols in Phimai, central Thailand during BASE-ASIA

    Science.gov (United States)

    Li, Can; Tsay, Si-Chee; Hsu, N. Christina; Kim, Jin Young; Howell, Steven G.; Huebert, Barry J.; Ji, Qiang; Jeong, Myeong-Jae; Wang, Sheng-Hsiang; Hansell, Richard A.; Bell, Shaun W.

    2013-10-01

    Comprehensive measurements of atmospheric aerosols were made in Phimai, central Thailand (15.183°N, 102.565°E, elevation: 206 m) during the BASE-ASIA field experiment from late February to early May in 2006. The observed aerosol loading was sizable for this rural site (mean aerosol scattering: 108 ± 64 Mm-1; absorption: 15 ± 8 Mm-1; PM10 concentration: 33 ± 17 μg m-3), and dominated by submicron particles. Major aerosol compounds included carbonaceous (OC: 9.5 ± 3.6 μg m-3; EC: 2.0 ± 2.3 μg m-3) and secondary species (SO42-: 6.4 ± 3.7 μg m-3, NH4+: 2.2 ± 1.3 μg m-3). While the site was seldom under the direct influence of large forest fires to its north, agricultural fires were ubiquitous during the experiment, as suggested by the substantial concentration of K+ (0.56 ± 0.33 μg m-3). Besides biomass burning, aerosols in Phimai during the experiment were also strongly influenced by industrial and vehicular emissions from the Bangkok metropolitan region and long-range transport from southern China. High humidity played an important role in determining the aerosol composition and properties in the region. Sulfate was primarily formed via aqueous phase reactions, and hygroscopic growth could enhance the aerosol light scattering by up to 60%, at the typical morning RH level of 85%. The aerosol single scattering albedo demonstrated distinct diurnal variation, ranging from 0.86 ± 0.04 in the evening to 0.92 ± 0.02 in the morning. This experiment marks the first time such comprehensive characterization of aerosols was made for rural central Thailand. Our results indicate that aerosol pollution has developed into a regional problem for northern Indochina, and may become more severe as the region's population and economy continue to grow.

  16. Stable hydrogen isotope composition of n-alkanes in urban atmospheric aerosols in Taiyuan, China

    Science.gov (United States)

    Bai, Huiling; Li, Yinghui; Peng, Lin; Liu, Xiangkai; Liu, Xiaofeng; Song, Chongfang; Mu, Ling

    2017-03-01

    The hydrogen isotope compositions (δD) of n-alkanes associated with particulate matter with a diameter of ≤10 μm from Taiyuan, China, during heating and non-heating periods were measured via gas chromatography-isotope ratio mass spectrometry to reveal the spatial and temporal characteristics of five functional zones and to provide another constraint on atmospheric pollutants. The δD values of n-C16 to n-C31 during the heating and non-heating periods ranged from -235.9‰ to -119.8‰ and from -231.3‰ to -129.2‰, respectively, but these similar spans had different distribution features. During the heating period, the δD distributions between non-central heating and commercial districts were consistent, as were those between residential and industrial districts; the n-alkanes came from two or more types of emission sources. Coal soot might be the primary local emission source, but not the only source. During the non-heating period, the n-alkanes of n-C16 to n-C20 were more depleted in D with the increasing carbon number in all functional zones, but there was no rule for n-C21 to n-C31. Specifically, coal soot and vehicle exhaust might be the primary sources of n-alkanes for non-central heating districts in the heating and non-heating periods, respectively, according to the δD distribution of n-C18 to n-C22; gasoline vehicle exhaust might be an n-alkane source, and the hydrogen isotope fractionation effect during the condensation process should be a pollution mechanism for the commercial district during the heating period; the δD distribution difference of n-C16 to n-C18 between the two periods in the residential and industrial districts was consistent, which indicates a similar source of fossil fuel combustion and a similar isotope fractionation effect during the non-heating period.

  17. Atmospheric changes caused by galactic cosmic rays over the period 1960-2010

    Science.gov (United States)

    Jackman, Charles H.; Marsh, Daniel R.; Kinnison, Douglas E.; Mertens, Christopher J.; Fleming, Eric L.

    2016-05-01

    The Specified Dynamics version of the Whole Atmosphere Community Climate Model (SD-WACCM) and the Goddard Space Flight Center two-dimensional (GSFC 2-D) models are used to investigate the effect of galactic cosmic rays (GCRs) on the atmosphere over the 1960-2010 time period. The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) computation of the GCR-caused ionization rates are used in these simulations. GCR-caused maximum NOx increases of 4-15 % are computed in the Southern polar troposphere with associated ozone increases of 1-2 %. NOx increases of ˜ 1-6 % are calculated for the lower stratosphere with associated ozone decreases of 0.2-1 %. The primary impact of GCRs on ozone was due to their production of NOx. The impact of GCRs varies with the atmospheric chlorine loading, sulfate aerosol loading, and solar cycle variation. Because of the interference between the NOx and ClOx ozone loss cycles (e.g., the ClO + NO2+ M → ClONO2+ M reaction) and the change in the importance of ClOx in the ozone budget, GCRs cause larger atmospheric impacts with less chlorine loading. GCRs also cause larger atmospheric impacts with less sulfate aerosol loading and for years closer to solar minimum. GCR-caused decreases of annual average global total ozone (AAGTO) were computed to be 0.2 % or less with GCR-caused column ozone increases between 1000 and 100 hPa of 0.08 % or less and GCR-caused column ozone decreases between 100 and 1 hPa of 0.23 % or less. Although these computed ozone impacts are small, GCRs provide a natural influence on ozone and need to be quantified over long time periods. This result serves as a lower limit because of the use of the ionization model NAIRAS/HZETRN which underestimates the ion production by neglecting electromagnetic and muon branches of the cosmic ray induced cascade. This will be corrected in future works.

  18. Mean ocean temperature change over the last glacial transition based on atmospheric changes in heavy noble mixing ratios

    Science.gov (United States)

    Bereiter, Bernhard; Severinghaus, Jeff; Shackleton, Sarah; Baggenstos, Daniel; Kawamura, Kenji

    2016-04-01

    On paleo-climatic timescales heavy noble gases (Krypton and Xenon) are passively cycled through the atmosphere-ocean system without seeing any significant sink or source. Since the solubility in water of each gas species is characterized by a specific temperature dependency, mixing ratios in the atmosphere change with changing ocean temperatures. In this study, we use this fact to reconstruct mean global ocean temperatures (MOT) over the course of the last glacial transition based on measurements of trapped air in the WAIS Divide ice core. We analyzed 70 ice samples with a recently developed method which determines the isotopic ratios of N2, Ar, Kr (and in some cases also of Xe, though with less precision) and the elemental ratios of Kr/N2, Xe/N2 and Xe/Kr. We use the isotope ratios to correct the elemental ratios for gravitational enrichment in the firn column. The corrected elemental ratios are then used in a simple box model to reconstruct MOT. The three elemental ratio pairs are first interpreted as independent measures of MOT and then combined to a single "best-estimate" MOT record with an average uncertainty of 0.27°C. We find a clear link to Antarctic temperatures and a LGM-Holocene change in MOT of 2.4°C. This value is in good agreement with results from marine sediment cores (which, however, have an uncertainty of 1°C). Our record provides an unprecedented constrain on ocean heat uptake over the last glacial transition and therefore gives new insights in the mechanisms underlying long term ocean heat fluxes. To our knowledge, this is the first time that MOT has been reconstructed in such great detail.

  19. P53 Mutations Change Phosphatidylinositol Acyl Chain Composition

    Directory of Open Access Journals (Sweden)

    Adam Naguib

    2015-01-01

    Full Text Available Phosphatidylinositol phosphate (PIP second messengers relay extracellular growth cues through the phosphorylation status of the inositol sugar, a signal transduction system that is deregulated in cancer. In stark contrast to PIP inositol head-group phosphorylation, changes in phosphatidylinositol (PI lipid acyl chains in cancer have remained ill-defined. Here, we apply a mass-spectrometry-based method capable of unbiased high-throughput identification and quantification of cellular PI acyl chain composition. Using this approach, we find that PI lipid chains represent a cell-specific fingerprint and are unperturbed by serum-mediated signaling in contrast to the inositol head group. We find that mutation of Trp53 results in PIs containing reduced-length fatty acid moieties. Our results suggest that the anchoring tails of lipid second messengers form an additional layer of PIP signaling in cancer that operates independently of PTEN/PI3-kinase activity but is instead linked to p53.

  20. Controllable thermal rectification realized in binary phase change composites.

    Science.gov (United States)

    Chen, Renjie; Cui, Yalong; Tian, He; Yao, Ruimin; Liu, Zhenpu; Shu, Yi; Li, Cheng; Yang, Yi; Ren, Tianling; Zhang, Gang; Zou, Ruqiang

    2015-03-09

    Phase transition is a natural phenomenon happened around our daily life, represented by the process from ice to water. While melting and solidifying at a certain temperature, a high heat of fusion is accompanied, classified as the latent heat. Phase change material (PCM) has been widely applied to store and release large amount of energy attributed to the distinctive thermal behavior. Here, with the help of nanoporous materials, we introduce a general strategy to achieve the binary eicosane/PEG4000 stuffed reduced graphene oxide aerogels, which has two ends with different melting points. It's successfully demonstrated this binary PCM composites exhibits thermal rectification characteristic. Partial phase transitions within porous networks instantaneously result in one end of the thermal conductivity saltation at a critical temperature, and therefore switch on or off the thermal rectification with the coefficient up to 1.23. This value can be further raised by adjusting the loading content of PCM. The uniqueness of this device lies in its performance as a normal thermal conductor at low temperature, only exhibiting rectification phenomenon when temperature is higher than a critical value. The stated technology has broad applications for thermal energy control in macroscopic scale such as energy-efficiency building or nanodevice thermal management.

  1. Atmospheric Change in Antarctica since the 1957--1958 International Geophysical Year

    Science.gov (United States)

    Nicolas, Julien Pierre

    The Antarctic Ice Sheet holds a volume of ice and snow equivalent to 55 meters of sea level. The melting of only a relatively small fraction of this volume could have dramatic consequences for populations around the world. With this in mind, the research presented here focuses on two atmospheric variables that are key controls of the state of the ice sheet: its surface mass balance (or net snowfall) and its near-surface air temperature. The analysis aims to understand how these two parameters have changed (if at all) since the 1957-1958 International Geophysical Year (IGY), the start of the instrumental era in Antarctica. Particular attention is given to the part of the continent known as West Antarctica, the most vulnerable to atmospheric and oceanic warming, and the one where rapid glacial change is currently taking place. The research is divided into three parts. The first part uses a set of seven global reanalyses to investigate the changes in Antarctic surface mass balance and Southern Ocean precipitation since 1979 (start of the reanalyses). This investigation is also intended to shed light on the reliability of these reanalyses, which often contained artifacts caused by changes in the observing system, particularly in high southern latitudes. Spurious changes in precipitation are found to various degrees in all data sets but with varying characteristics and origins. According to the two reanalyses deemed most reliable, neither Antarctic surface mass balance nor Southern Ocean precipitation have changed significantly over the past three decades. The second part consists of a multifaceted investigation of the near-surface temperature record from Byrd Station, in central West Antarctica. As the only meteorological record in this region to extend back to the IGY, it is a critical data set, but also one with a complicated history and substantial data gaps. A comprehensive revision of the record is undertaken and a novel approach is used to estimate the missing

  2. Study of the Role of Terrestrial Processes in the Carbon Cycle Based on Measurements of the Abundance and Isotopic Composition of Atmospheric CO2

    Energy Technology Data Exchange (ETDEWEB)

    Piper, Stephen C; Keeling, Ralph F

    2012-01-03

    The main objective of this project was to continue research to develop carbon cycle relationships related to the land biosphere based on remote measurements of atmospheric CO2 concentration and its isotopic ratios 13C/12C, 18O/16O, and 14C/12C. The project continued time-series observations of atmospheric carbon dioxide and isotopic composition begun by Charles D. Keeling at remote sites, including Mauna Loa, the South Pole, and eight other sites. Using models of varying complexity, the concentration and isotopic measurements were used to study long-term change in the interhemispheric gradients in CO2 and 13C/12C to assess the magnitude and evolution of the northern terrestrial carbon sink, to study the increase in amplitude of the seasonal cycle of CO2, to use isotopic data to refine constraints on large scale changes in isotopic fractionation which may be related to changes in stomatal conductance, and to motivate improvements in terrestrial carbon cycle models. The original proposal called for a continuation of the new time series of 14C measurements but subsequent descoping to meet budgetary constraints required termination of measurements in 2007.

  3. Exploring Io's atmospheric composition with APEX: first measurement of 34SO2 and tentative detection of KCl

    CERN Document Server

    Moullet, A; Moreno, R; Gurwell, M; Black, J; Butler, B

    2013-01-01

    The composition of Io's tenuous atmosphere is poorly constrained. Only the major species SO2 and a handful of minor species have been positively identified, but a variety of other molecular species should be present, based on thermochemical equilibrium models of volcanic gas chemistry and the composition of Io's environment. This paper focuses on the spectral search for expected yet undetected molecular species (KCl, SiO, S2O) and isotopes (34SO2). We analyze a disk-averaged spectrum of a potentially line-rich spectral window around 345 GHz, obtained in 2010 at the APEX-12m antenna (Atacama Pathfinder EXperiment). Using different models assuming either extended atmospheric distributions or a purely volcanically-sustained atmosphere, we tentatively measure the KCl relative abundance with respect to SO2 and derive a range of 4x10^{-4}-8x10^{-3}. We do not detect SiO or S2O and present new upper limits on their abundances. We also present the first measurement of the 34S/32S isotopic ratio in gas phase on Io, wh...

  4. Grassland/atmosphere response to changing climate: Coupling regional and local scales. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Coughenour, M.B.; Kittel, T.G.F.; Pielke, R.A.; Eastman, J.

    1993-10-01

    The objectives of the study were: to evaluate the response of grassland ecosystems to atmospheric change at regional and site scales, and to develop multiscaled modeling systems to relate ecological and atmospheric models with different spatial and temporal resolutions. A menu-driven shell was developed to facilitate use of models at different temporal scales and to facilitate exchange information between models at different temporal scales. A detailed ecosystem model predicted that C{sub 3} temperate grasslands wig respond more strongly to elevated CO{sub 2} than temperate C{sub 4} grasslands in the short-term while a large positive N-PP response was predicted for a C{sub 4} Kenyan grassland. Long-term climate change scenarios produced either decreases or increases in Colorado plant productivity (NPP) depending on rainfall, but uniform increases in N-PP were predicted in Kenya. Elevated CO{sub 2} is likely to have little effect on ecosystem carbon storage in Colorado while it will increase carbon storage in Kenya. A synoptic climate classification processor (SCP) was developed to evaluate results of GCM climate sensitivity experiments. Roughly 80% agreement was achieved with manual classifications. Comparison of lx and 2xCO{sub 2} GCM Simulations revealed relatively small differences.

  5. Recent changes in winter Arctic clouds and their relationships with sea ice and atmospheric conditions

    Directory of Open Access Journals (Sweden)

    Sang-Yoon Jun

    2016-03-01

    Full Text Available Changes in Arctic clouds during boreal winter (December through February and their relationship with sea ice and atmospheric conditions in recent decades have been examined using satellite and reanalysis data, and they are compared with output data from atmospheric general circulation model (AGCM experiments. All the datasets used in this study consistently show that cloud amount over the Arctic Ocean (north of 67°N decreased until the late 1990s but rapidly increased thereafter. Cloud increase in recent decade was a salient feature in the lower troposphere over a large part of the Arctic Sea, in association with obvious increase of lower tropospheric temperature and moisture. The comparison between the two periods before and after 1997 indicates that interannual covariability of Arctic clouds and lower tropospheric temperature and moisture was significantly enhanced after the late 1990s. Large reduction of sea ice cover during boreal winter decreased lower tropospheric static stability and deepened the planetary boundary layer. These changes led to an enhanced upward moisture transport and cloud formation, which led to considerable longwave radiative forcing and, as a result, strengthened the cloud–moisture–temperature relationship in the lower troposphere. AGCM experiments under reduced sea ice conditions support those results obtained by satellite and reanalysis datasets reproducing the increases in cloud amount and lower tropospheric temperature and their enhanced covariability.

  6. Projected changes in atmospheric rivers affecting Europe in CMIP5 models

    Science.gov (United States)

    Ramos, Alexandre M.; Tomé, Ricardo; Trigo, Ricardo M.; Liberato, Margarida L. R.; Pinto, Joaquim G.

    2016-09-01

    Atmospheric Rivers (ARs) are elongated bands of high water vapor concentration extending to the midlatitudes, which can be associated with intense precipitation and floods over continental areas. We analyze ARs reaching Europe in simulations from six Coupled Model Intercomparison Project Phase 5 (CMIP5) global climate models (GCMs) to quantify possible changes during the current century, with emphasis in five western European prone coastal areas. ARs are represented reasonably well in GCMs for recent climate conditions (1980-2005). Increased vertically integrated horizontal water transport is found for 2074-2099 (RCP4.5 and RCP8.5) compared to 1980-2005, while the number of ARs is projected to double on average for the same period. These changes are robust between models and are associated with higher air temperatures and thus enhanced atmospheric moisture content, together with higher precipitation associated with extratropical cyclones. This suggests an increased risk of intense precipitation and floods along the Atlantic European Coasts from the Iberian Peninsula to Scandinavia.

  7. Large Scale Atmospheric Dynamics: a Major Paradigm Change, with a Solar Spinoff

    Science.gov (United States)

    McIntyre, M. E.

    2011-12-01

    Over the past century, there has been a gradual but profound paradigm change in the way we think about global-scale atmospheric circulations and the eddy transport processes involved, especially those responsible for the global-scale eddy transport of angular momentum. In the first half of the 20th century, it was usual to think of the eddy momentum transport as "turbulent", because of the enormous Reynolds numbers involved. The new paradigm recognizes that wave-induced momentum transport -- "radiation stress" in the language of physics -- is dominant. This easily solves what used to be regarded as three great atmospheric-dynamics enigmas of the mid-twentieth century: first Starr's "negative viscosity", second the cause of the quasi-biennial oscillation, and third the extreme coldness of the summer mesopause. The same paradigm change has recently led, moreover, to a breakthrough in understanding the Sun's internal differential rotation. Some of the historical twists and turns well illustrate the "Michelson-Morley principle" that negative results in science can have far-reaching importance.

  8. Changes in Atlantic Thermohaline Circulation under Different Atmospheric CO2 Scenarios in a Climate Model

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The changes in the thermohaline circulation (THC) because of the increased CO2 in the atmosphere play an important role in future climate regimes.In this article, a new climate model developed at the Max-Planck Institute for Meteorology is used to study the variation in THC strength, the changes of North Atlantic deep-water (NADW) formation, and the regional responses of the THC in the North Atlantic to increasing atmospheric CO2.From 2000 to 2100, under increased CO2 scenarios (B1, A1B, and A2), the strength of THC decreases by 4 Sv (106 m3/s), 5.1 Sv, and 5.2 Sv, respectively, equivalent to a reduction of 20%, 25%, and 25.1% of the present THC strength.The analyses show that the oceanic deep convective activity significantly strengthens in the Greenland-Iceland-Norway(GIN) Seas owing to saltier (denser) upper oceans, whereas weakens in the Labrador Sea and in the south of the Denmark Strait region (SDSR) because of surface warming and freshening due to global warming.The saltiness of the GIN Seas is mainly caused by the increase of the saline North Atlantic inflow through the Faro-Bank (FB) Channel.Under the scenario A1B, the deep-water formation rate in the North Atlantic decreases from 16.2 Sv to 12.9 Sv with increasing CO2.

  9. Climate change on the Tibetan Plateau in response to shifting atmospheric circulation since the LGM

    Science.gov (United States)

    Zhu, Liping; Lü, Xinmiao; Wang, Junbo; Peng, Ping; Kasper, Thomas; Daut, Gerhard; Haberzettl, Torsten; Frenzel, Peter; Li, Quan; Yang, Ruimin; Schwalb, Antje; Mäusbacher, Roland

    2015-01-01

    The Tibetan Plateau (TP) is primarily influenced by the northern hemispheric middle latitude Westerlies and the Indian summer monsoon (ISM). The extent, long-distance effects and potential long-term changes of these two atmospheric circulations are not yet fully understood. Here, we analyse modern airborne pollen in a transition zone of seasonally alternating dominance of the Westerlies and the ISM to develop a pollen discrimination index (PDI) that allows us to distinguish between the intensities of the two circulation systems. This index is applied to interpret a continuous lacustrine sedimentary record from Lake Nam Co covering the past 24 cal kyr BP to investigate long-term variations in the atmospheric circulation systems. Climatic variations on the central TP widely correspond to those of the North Atlantic (NA) realm, but are controlled through different mechanisms resulting from the changing climatic conditions since the Last Glacial Maximum (LGM). During the LGM, until 16.5 cal kyr BP, the TP was dominated by the Westerlies. After 16.5 cal kyr BP, the climatic conditions were mainly controlled by the ISM. From 11.6 to 9 cal kyr BP, the TP was exposed to enhanced solar radiation at the low latitudes, resulting in greater water availability. PMID:26294226

  10. IR and UV laser-induced morphological changes in silicon surface under oxygen atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez-Jarquin, J.; Fernandez-Guasti, M.; Haro-Poniatowski, E.; Hernandez-Pozos, J.L. [Laboratorio de Optica Cuantica, Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco No. 186, Col. Vicentina, C.P. 09340, Mexico D.F. (Mexico)

    2005-08-01

    We irradiated silicon (100) wafers with IR (1064 nm) and UV (355 nm) nanosecond laser pulses with energy densities within the ablation regime and used scanning electron microscopy to analyze the morphological changes induced on the Si surface. The changes in the wafer morphology depend both on the incident radiation wavelength and the environmental atmosphere. We have patterned Si surfaces with a single focused laser spot and, in doing the experiments with IR or UV this reveals significant differences in the initial surface cracking and pattern formation, however if the experiment is carried out in O{sub 2} the final result is an array of microcones. We also employed a random scanning technique to irradiate the silicon wafer over large areas, in this case the microstructure patterns consist of a ''semi-ordered'' array of micron-sized cones. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Exploration of GOMOS, OSIRIS, OMI and MIPAS Measurements for Studying the Change in the Middle Atmosphere (EGOMO)

    Science.gov (United States)

    Kyrola, Erkki; Sofieva, Viktoria; Kalakoski, Niilo; Liu, Yi; Liu, Chuanxi; Cai, Zhaonan; Lu, Chunhui

    2013-01-01

    investigated using measurements from GOMOS and MLS on EOS-Aura. Significant changes in the chemical composition of the middle atmosphere were found. These changes are not restricted to stratosphere but they extend to mesosphere and lower thermosphere and they are influenced by chemical and dynamical processes. The experimental spatio-temporal distributions have been compared with the ones calculated by the FinROSE chemistry-transport model and generally a good agreement was found for stratospheric changes. Other research activities within the project include studies of gravity wave activity and breaking during sudden stratospheric warmings (using the GOMOS scintillation measurements), analyses of small-scale variability of ozone field (using GOMOS and ozone sonde data), the formation of a record ozone minihole over the Tibetan Plateau in December 2003 (using GOMOS and MIPAS on ENVISAT data), and studies related to spring-time ozone asymmetry over Antarctica caused by planetary wave activity (using OMI on EOS-Aura, GOMOS and MLS measurements).

  12. Changes in the Composition of the Fram Strait Freshwater Outflow

    Science.gov (United States)

    Dodd, Paul; Granskog, Mats; Fransson, Agneta; Chierici, Melissa; Stedmon, Colin

    2016-04-01

    Fram Strait is the largest gateway and only deep connection between the Arctic Ocean and the subpolar oceans. Monitoring the exchanges through Fram Strait allows us to detect and understand current changes occurring in the Arctic Ocean and to predict the effects of those changes on the Arctic and Subarctic climate and ecosystems. Polar water, recirculating Atlantic Water and deeper water masses exported from the Arctic Ocean through western Fram Strait are monitored year-round by an array of moored instruments along 78°50'N, continuously maintained by the Norwegian Polar Institute since the 1990s. Complimentary annual hydrographic sections have been repeated along the same latitude every September. This presentation will focus on biogeochemical tracer measurements collected along repeated sections from 1997-2015, which can be used to identify freshwater from different sources and reveal the causes of variations in total volume of freshwater exported e. g.: pulses of freshwater from the Pacific. Repeated tracer sections across Fram Strait reveal significant changes in the composition of the outflow in recent years, with recent sections showing positive fractions of sea ice meltwater at the surface near the core of the EGC, suggesting that more sea ice melts back into the surface than previously. The 1997-2015 time series of measurements reveals a strong anti-correlation between run-off and net sea ice meltwater inventories, suggesting that run-off and brine may be delivered to Fram Strait together from a common source. While the freshwater outflow at Fram Strait typically exhibits a similar run-off to net sea ice meltwater ratio to the central Arctic Ocean and Siberian shelves, we find that the ratio of run-off to sea ice meltwater at Fram Strait is decreasing with time, suggesting an increased surface input of sea ice meltwater in recent years. In 2014 and 2015 measurements of salinity, δ18O and total alkalinity were collected from sea ice cores as well as the

  13. Two centuries of observed atmospheric variability and change over the North Sea region

    Science.gov (United States)

    Stendel, Martin; van den Besselaar, Else; Hannachi, Abdel; Kent, Elizabeth; Lefebvre, Christiana; Rosenhagen, Gudrun; Schenk, Frederik; van der Schrier, Gerard; Woollings, Tim

    2016-04-01

    In the upcoming North Sea Region Climate Change Assessment (NOSCCA), we present a synthesis of current knowledge about past, present and possible future climate change in the North Sea region. A climate change assessment from published scientific work has been conducted as a kind of regional IPCC report, and a book has been produced that will be published by Springer in 2016. In the framework of the NOSCCA project, we examine past and present studies of variability and changes in atmospheric variables within the North Sea region over the instrumental period, roughly the past 200 years, based on observations and reanalyses. The variables addressed in this presentation are large-scale circulation, pressure and wind, surface air temperature, precipitation and radiative properties (clouds, solar radiation, and sunshine duration). While air temperature over land, not unexpectedly, has increased everywhere in the North Sea region, with strongest trends in spring and in the north of the region, a precipitation increase has been observed in the north and a decrease in the south of the region. This pattern goes along with a north-eastward shift of storm tracks and is in agreement with climate model projections under enhanced greenhouse gas concentrations. For other variables, it is not obvious which part of the observed changes may be due to anthropogenic activities and which is internally forced. It remains also unclear to what extent atmospheric circulation over the North Sea region is influenced by distant factors, in particular Arctic sea-ice decline in recent decades. There are indications of an increase in the number of deep cyclones (but not in the total number of cyclones), while storminess since the late 19th century shows no robust trends. The persistence of circulation types appears to have increased over the last century, and consequently, there is an indication for 'more extreme' extreme events. However, changes in extreme weather events are difficult to assess

  14. Were ancient granitoid compositions influenced by contemporaneous atmospheric and hydrosphere oxidation states?Were ancient granitoid compositions influenced by contemporaneous atmospheric and hydrosphere oxidation states?

    Science.gov (United States)

    Jagoutz, Oliver

    2014-05-01

    A fundamental shift in the nature of granitoids occurs at approximately the Archean-Proterozoic boundary. Archean crust is dominated Na-rich tonalite-trondhjemite-granodiorites (TTGs), whereas post-Archean granitoids are characterized by K-rich granodiorite-granite (GG). Due to the HREE depletion commonly found in TTGs indicating the presence of residual garnet, many researchers have proposed that the difference in Na/K is related to the deeper melting depth of the TTG parental liquids. Here I present a compilation of the relevant experimental data, documenting that no correlation exists between the Na/K of derivative felsic liquids and the pressure of partial melting/fractional crystallization. Instead, the Na/K ratio of the felsic liquid best correlates with the Na/K ratio of the source. This implies that in Archean time the source material of TTG rocks must have been Na/K enriched relative to the modern. Modern granitoids are dominantly formed in a supra subduction zone environment, where a feedback loop exists between subducted materials (oceanic crust and sediments) and arc magmatism. Sea-floor weathering and the Na/K of the altered oceanic crust strongly depends on f(O2) conditions during alteration, which likely changed with earth history. During alteration under oxidized condition K2O is fixated due to the formation of celadonite (K-Mica), wheres during anoxic condition saponite (Na-Smectite) is the stable alteration mineral. I propose that the rise of oxygen at 2600-2400 Ma triggered associated changes in f(O2) seafloor alteration conditions. The change in the dominant seafloor alteration mineral from reduced to oxidized causes a change in the nature of the arc magma source and provides a possible explanation for the observed transition from TTGrocks in the Archean to the GG-granitoids in post-Archean times.

  15. Atmospheric and Oceanic Excitations to LOD Change on Quasi-biennial Time Scales

    Institute of Scientific and Technical Information of China (English)

    Li-Hua Ma; De-Chun Liao; Yan-Ben Han

    2006-01-01

    We use wavelet transform to study the time series of the Earth's rotation rate (length-of-day, LOD), the axial components of atmospheric angular momentum (AAM) and oceanic angular momentum (OAM) in the period 1962-2005, and discuss the quasi-biennial oscillations (QBO) of LOD change. The results show that the QBO of LOD change varies remarkably in amplitude and phase. It was weak before 1978, then became much stronger and reached maximum values during the strong El Nino events in around 1983 and 1997. Results from analyzing the axial AAM indicate that the QBO signals in axial AAM are extremely consistent with the QBOs of LOD change. During 1963-2003, the QBO variance in the axial AAM can explain about 99.0% of that of the LOD, in other words, all QBO signals of LOD change are almost excited by the axial AAM, while the weak QBO signals of the axial OAM are quite different from those of the LOD and the axial AAM in both time-dependent characteristics and magnitudes. The combined effects of the axial AAM and OAM can explain about 99.1% of the variance of QBO in LOD change during this period.

  16. Heterogeneous Oxidation of Atmospheric Organic Aerosol: Kinetics of Changes to the Amount and Oxidation State of Particle-Phase Organic Carbon.

    Science.gov (United States)

    Kroll, Jesse H; Lim, Christopher Y; Kessler, Sean H; Wilson, Kevin R

    2015-11-01

    Atmospheric oxidation reactions are known to affect the chemical composition of organic aerosol (OA) particles over timescales of several days, but the details of such oxidative aging reactions are poorly understood. In this study we examine the rates and products of a key class of aging reaction, the heterogeneous oxidation of particle-phase organic species by the gas-phase hydroxyl radical (OH). We compile and reanalyze a number of previous studies from our laboratories involving the oxidation of single-component organic particles. All kinetic and product data are described on a common basis, enabling a straightforward comparison among different chemical systems and experimental conditions. Oxidation chemistry is described in terms of changes to key ensemble properties of the OA, rather than to its detailed molecular composition, focusing on two quantities in particular, the amount and the oxidation state of the particle-phase carbon. Heterogeneous oxidation increases the oxidation state of particulate carbon, with the rate of increase determined by the detailed chemical mechanism. At the same time, the amount of particle-phase carbon decreases with oxidation, due to fragmentation (C-C scission) reactions that form small, volatile products that escape to the gas phase. In contrast to the oxidation state increase, the rate of carbon loss is nearly uniform among most systems studied. Extrapolation of these results to atmospheric conditions indicates that heterogeneous oxidation can have a substantial effect on the amount and composition of atmospheric OA over timescales of several days, a prediction that is broadly in line with available measurements of OA evolution over such long timescales. In particular, 3-13% of particle-phase carbon is lost to the gas phase after one week of heterogeneous oxidation. Our results indicate that oxidative aging represents an important sink for particulate organic carbon, and more generally that fragmentation reactions play a major

  17. Temperature induced changes in the heterocyst glycolipid composition of N

    NARCIS (Netherlands)

    Bauersachs, T.; Stal, L.J.; Grego, M.; Schwark, L.; Schwark, L.

    2014-01-01

    We investigated the effect of temperature on the heterocyst glycolipid (HG) composition of the diazotrophic heterocystous cyanobacteria Anabaena sp. strain CCY9613 and Nostoc sp. strain CCY9926 grown at 9, 12, 16, 20 and 24 degrees C. Both strains contained an overall similar composition of heterocy

  18. Correlations in the chemical composition of rural background atmospheric aerosol in the UK determined in real time using time-of-flight mass spectrometry.

    Science.gov (United States)

    Beddows, David C S; Donovan, Robert J; Harrison, Roy M; Heal, Mathew R; Kinnersley, Robert P; King, Martin D; Nicholson, David H; Thompson, Katherine C

    2004-02-01

    An aerosol time-of-flight mass spectrometer (ATOFMS) was used to determine, in real time, the size and chemical composition of individual particles in the atmosphere at the remote inland site of Eskdalemuir, Scotland. A total of 51,980 particles, in the size range 0.3-7.4 microm, were detected between the 25th and 30th June 2001. Rapid changes in the number density, size and chemical composition of the atmospheric aerosol were observed. These changes are attributed to two distinct types of air mass; a polluted air mass that had passed over the British mainland before reaching Eskdalemuir, interposed between two cleaner air masses that had arrived directly from the sea. Such changes in the background aerosol could clearly be very important to studies of urban aerosols and attempts at source apportionment. The results of an objective method of data analysis are presented. Correlations were sought between the occurrence of: lithium, potassium, rubidium, caesium, beryllium, strontium, barium, ammonium, amines, nitrate, nitrite, boron, mercury, sulfate, phosphate, fluorine, chlorine, bromine, iodine and carbon (both elemental and organic hydrocarbon) in both fine (d 2.5 microm) particle fractions. Several previously unreported correlations were observed, for instance between the elements lithium, beryllium and boron. The results suggest that about 2 in 3 of all fine particles (by number rather than by mass), and 1 in 2 of all coarse particles containing carbon, consisted of elemental carbon rather than organic hydrocarbon (although a bias in the sensitivity of the ATOFMS could have affected these numbers). The ratio of the number of coarse particles containing nitrate anions to the number of particles containing chloride anions exceeded unity when the air mass had travelled over the British mainland. The analysis also illustrates that an air mass of marine origin that had travelled slowly over agricultural land can accumulate amines and ammonium.

  19. Changes in nutrient and antinutrient composition of Vigna racemosa flour in open and controlled fermentation

    OpenAIRE

    Difo, V. H.; Onyike, E.; D.A. Ameh; Njoku, G. C.; Ndidi, U. S.

    2014-01-01

    This study was conducted to investigate the effect of open and controlled fermentation on the proximate composition, mineral elements, antinutritional factors and flatulence-causing oligosaccharides in Vigna racemosa. The open fermentation was carried out using the microorganisms present in the atmosphere while the controlled fermentation was carried out using Aspergillus niger as a starter. The proximate composition of the Vigna racemosa, some anti-nutrients and the mineral elements were ana...

  20. Combining projected changes in species richness and composition reveals climate change impacts on coastal Mediterranean fish assemblages

    DEFF Research Database (Denmark)

    Albouy, Camille; Guilhaumon, François; Bastos Araujo, Miguel;

    2012-01-01

    Species Temporal Turnover (STT) is one of the most familiar metrics to assess changes in assemblage composition as a consequence of climate change. However, STT mixes two components in one metric, changes in assemblage composition caused by a process of species loss or gain (i.e. the nestedness...... component) and changes in assemblage composition caused by a process of species replacement (i.e. the species replacement component). Drawing on previous studies investigating spatial patterns of beta diversity, we propose measures of STT that allow analysing each component (species replacement vs....... nestedness), separately. We also present a mapping strategy to simultaneously visualize changes in species richness and assemblage composition. To illustrate our approach, we used the Mediterranean coastal fish fauna as a case study. Using Bioclimatic Envelope Models (BEMs) we first projected the potential...

  1. Effect of Pollution Controls on Atmospheric PM2.5 Composition during Universiade in Shenzhen, China

    Directory of Open Access Journals (Sweden)

    Nitika Dewan

    2016-04-01

    Full Text Available The 16th Universiade, an international multi-sport event, was hosted in Shenzhen, China from 12 to 23 August 2011. During this time, officials instituted the Pearl River Delta action plan in order to enhance the air quality of Shenzhen. To determine the effect of these controls, the current study examined the trace elements, water-soluble ions, and stable lead isotopic ratios in atmospheric particulate matter (PM collected during the controlled (when the restrictions were in place and uncontrolled periods. Fine particles (PM2.5 were collected at two sampling sites in Shenzhen: “LG”—a residential building in the Longgang District, with significant point sources around it and “PU”—Peking University Shenzhen Graduate School in the Nanshan District, with no significant point sources. Results from this study showed a significant increase in the concentrations of elements during the uncontrolled periods. For instance, samples at the LG site showed (controlled to uncontrolled periods concentrations (in ng·m−3 of: Fe (152 to 290, As (3.65 to 8.38, Pb (9.52 to 70.8, and Zn (98.6 to 286. Similarly, samples at the PU site showed elemental concentrations (in ng·m−3 of: Fe (114 to 301, As (0.634 to 8.36, Pb (4.86 to 58.1, and Zn (29.5 to 259. Soluble Fe ranged from 7%–15% for the total measured Fe, indicating an urban source of Fe. Ambient PM2.5 collected at the PU site has an average 206Pb/204Pb ratio of 18.257 and 18.260 during controlled and uncontrolled periods, respectively. The LG site has an average 206Pb/204Pb ratio of 18.183 and 18.030 during controlled and uncontrolled periods, respectively. The 206Pb/204Pb ratios at the PU and the LG sites during the controlled and uncontrolled periods were similar, indicating a common Pb source. To characterize the sources of trace elements, principal component analysis was applied to the elements and ions. Although the relative importance of each component varied, the major sources for both

  2. Atmospheric Rivers in the Southwestern US: Climatology and Possible Future Changes

    Science.gov (United States)

    Dominguez, F.; Rivera-fernandez, E. R.

    2014-12-01

    Atmospheric rivers (ARs) are important contributors to cool season precipitation in the Southwestern US, and in some cases can lead to extreme hydrometeorological events in the region. We performed a climatological analysis and identified two predominant types of ARs that affect the Southwest: Type 1 ARs originate in the tropics near Hawaii (central Pacific) and enhance their moisture in the midlatitudes, with maximum moisture transport over the ocean at low-levels of the troposphere. On the other hand, moisture in Type 2 ARs has a more direct tropical origin and meridional orientation with maximum moisture transfer at mid-levels. We then analyze future projections of Southwest ARs in a suite of global and regional climate models (from NARCCAP), to evaluate projected future changes in the frequency and intensity of ARs under warmer global climate conditions. We find a consistent and clear intensification of the water vapor transport associated with the ARs that impinge upon Arizona and adjacent regions, however, the response of AR-related precipitation intensity to increased moisture flux and column-integrated water vapor is weak and no robust variations are projected either by the GCMs or the NARCCAP models. To evaluate the effect of horizontal resolution and improve our physical understanding of these results, we numerically simulated a historical AR event using the Weather Research and Forecasting (WRF) model at a 3km resolution. We then performed a pseudo-global warming experiment by modifying the lateral and lower boundary conditions to reflect possible changes in future ARs (as projected by the ensemble of GCM simulations used for NARCCAP). Interestingly we find that despite higher specific humidity, some regions still receive less rainfall in the warming climate experiments - partially due to changes in thermodynamics, but primarily due to AR dynamics. Therefore, we conclude from this analysis that overall future increase in atmospheric temperature and water

  3. Anthropogenic non-methane volatile hydrocarbons at Mt. Cimone (2165 m a.s.l., Italy): Impact of sources and transport on atmospheric composition

    Science.gov (United States)

    Lo Vullo, Eleonora; Furlani, Francesco; Arduini, Jgor; Giostra, Umberto; Graziosi, Francesco; Cristofanelli, Paolo; Williams, Martin L.; Maione, Michela

    2016-09-01

    To advance our understanding of the factors that affect pollution in mountainous areas, long-term, high frequency measurements of thirteen Non Methane Volatile Organic Compounds (NMVOCs) have been carried out at the atmospheric observatory on the top of Mt. Cimone (2165 m a.s.l.), whose location is ideal for sampling both aged air masses representing the regional background and polluted air masses coming from nearby sources of anthropogenic pollution. An analysis of the NMVOC time series available at Mt. Cimone during 2010-2014 was used to examine the influence of transport processes on NMVOC atmospheric composition and to derive information on the emission sources. We performed a multifactor principal component analysis whose results allowed us to identify the source categories emitting the NMVOCs measured at Mt. Cimone as well as to assess transport ranges in winter and summer. Aged air masses, due to long-range transport and related to vehicular traffic exhaust emissions accounted for 78% of the NMVOC variability in winter and 62% in summer, whereas evaporative emissions, likely to be associated with fresh emissions from nearby sources, accounted for 12% of the NMVOC variability and 24% in winter and summer, respectively. Such results have been confirmed by a further analysis in which the NMVOC variability as a function of their atmospheric lifetimes has been evaluated. The ratios of alkane isomers potentially provides a metric to investigate seasonal changes in NMVOCs composition and in the emission fields of butanes and pentanes, suggesting that during the summer the butanes are originating mainly from the European domain and that for pentanes non-anthropogenic sources may be contributing to the measured concentrations.

  4. Heavy metals and trace elements in atmospheric fall-out: Their relationship with topsoil and wheat element composition

    Energy Technology Data Exchange (ETDEWEB)

    Bermudez, Gonzalo M.A., E-mail: gbermudez@com.uncor.edu [Instituto Multidisciplinario de Biologia Vegetal (IMBIV), CONICET (Argentina); Catedra de Quimica General, FCEFyN, Universidad Nacional de Cordoba, Avda. Velez Sarsfield 1611, Ciudad Universitaria (X5016 GCA), Cordoba (Argentina); Jasan, Raquel; Pla, Rita [Tecnicas Analiticas Nucleares, Comision Nacional de Energia Atomica (CAE), Presbitero Gonzalez y Aragon N Degree-Sign 15 (B1802AYA), Ezeiza (Argentina); Pignata, Maria L. [Instituto Multidisciplinario de Biologia Vegetal (IMBIV), CONICET (Argentina); Catedra de Quimica General, FCEFyN, Universidad Nacional de Cordoba, Avda. Velez Sarsfield 1611, Ciudad Universitaria (X5016 GCA), Cordoba (Argentina)

    2012-04-30

    Highlights: Black-Right-Pointing-Pointer Metal and trace element deposition rates and concentrations in bulk samples. Black-Right-Pointing-Pointer Anthropogenic vs. natural sources were identified using enrichment factors and PCA. Black-Right-Pointing-Pointer Anthropogenic sources for Ca, Cd, Cu, Fe, Mn, Ni, Pb, Sb, U, Zn and lanthanides. Black-Right-Pointing-Pointer Main sources were a cement plant, chemical-mechanical industries, cities and mining. Black-Right-Pointing-Pointer Metals in wheat grain were predicted by soil and bulk deposition composition. - Abstract: The objectives of this study were to determine the average concentrations and deposition rates of 28 elements in atmospheric bulk deposition and to elucidate associations among topsoil, bulk deposition and wheat element composition. The fluxes of arsenic (As), copper (Cu), lead (Pb) and zinc (Zn) deposition in Cordoba were higher than in other agro-ecosystems, which reflects both natural (geochemistry and topsoil removal) and anthropogenic sources. High lanthanide, uranium (U) and thorium (Th) concentrations revealed the impact of an open cast uranium mine. The highest enrichment factors (EF) were those of Cu, Pb, Zn and nickel (Ni), with calcium (Ca) being the most prominent in the surroundings of a cement plant. Industries and the transport of airborne urban pollutants were the main anthropogenic sources for Ca, Cu, Ni, Pb, Zn, cadmium (Cd), iron (Fe), manganese (Mn) and antimony (Sb). The concentrations of metals in wheat grain were predicted using the topsoil and atmospheric fall-out composition with R{sup 2} = 0.90, with the latter being the best explanatory variable. The present study highlights the potential health hazards of wheat consumption (Environmental Protection Agency) by the assessment of heavy metals in bulk atmospheric deposition.

  5. Atmospheric response to Indian Ocean Dipole forcing: changes of Southeast China winter precipitation under global warming

    Science.gov (United States)

    Zhang, Ling; Sielmann, Frank; Fraedrich, Klaus; Zhi, Xiefei

    2017-03-01

    To investigate the relationship between autumn Indian Ocean Dipole (IOD) events and the subsequent winter precipitation in Southeast China (SEC), observed fields of monthly precipitation, sea surface temperature (SST) and atmospheric circulation are subjected to a running and a maximum correlation analysis. The results show a significant change of the relevance of IOD for the early modulation of SEC winter precipitation in the 1980s. After 1980, positive correlations suggest prolonged atmospheric responses to IOD forcing, which are linked to an abnormal moisture supply initiated in autumn and extended into the subsequent winter. Under global warming two modulating factors are relevant: (1) an increase of the static stability has been observed suppressing vertical heat and momentum transports; (2) a positive (mid-level) cloud-radiation feedback jointly with the associated latent heating (apparent moisture sink Q2) explains the prolongation of positive as well as negative SST anomalies by conserving the heating (apparent heat source Q1) in the coupled atmosphere-ocean system. During the positive IOD events in fall (after 1980) the dipole heating anomalies in the middle and lower troposphere over the tropical Indian Ocean are prolonged to winter by a positive mid-level cloud-radiative feedback with latent heat release. Subsequently, thermal adaptation leads to an anticyclonic anomaly over Eastern India overlying the anomalous cooling SST of the tropical Eastern Indian Ocean enhancing the moisture flow from the tropical Indian Ocean through the Bay of Bengal into South China, following the northwestern boundary of the anticyclonic circulation anomaly over east India, thereby favoring abundant precipitation in SEC.

  6. Resilience of the Asian atmospheric circulation to paleogeographic and climatic changes

    Science.gov (United States)

    Licht, Alexis; Dupont-Nivet, Guillaume; Pullen, Alex; Kapp, Paul; Abels, Hemmo; Abell, Jordan; Giesler, Dominique

    2016-04-01

    At the southwestern margin of the Chinese Loess Plateau in the Xining Basin, Eocene-Oligocene red mudstones have been interpreted as isolated remnants of dust deposits based on grain-size distribution and quartz grain morphology. These deposits have not received the focus that the Plio-Quaternary Loess Plateau strata have received though they could provide an opportunity to document late Paleogene regional atmospheric circulation and the early mechanisms of central Asian aridification. Here, we used single-grain U-Pb dating of multiple detrital zircons to constrain their provenance. Red mudstone strata yield statistically different age distributions when compared to coeval fluvial sandstones from the Xining Basin, thus corroborating distal aeolian transport. Comparison with Paleogene regional age distributions indicates that provenance of the red mudstones is well-explained by a combination of surface westerly, dust-generating winds blowing along the northern margin of the Tibetan Plateau and recycling of locally-sourced fluvial sediment. We thus propose that dust accumulation in central China has been occurring during most of the Cenozoic but that Paleogene deposits are rare because of long-term deflation and recycling into younger terrestrial loess deposits and into the Northern Pacific Ocean. The inferred Paleogene arid surface conditions along the northern margin of the Tibetan Plateau, despite the presence of an extended seaway in central Asia -the Tarim Sea, suggest the presence of a strong subtropical high in central China. Evidence of orbitally-controlled lacustrine phases inter-fingered within the red mudstones indicates regular weakening or shifting of this subtropical high and mirrors the Plio-Quaternary monsoonal atmospheric circulation dynamics in central Asia. These findings thus indicate that synoptic-level atmospheric circulation over central Asia has changed little since middle Eocene time and suggest that the retreat of the Tarim Sea and the

  7. CAPRICE98: A balloon borne magnetic spectrometer to study cosmic ray antimatter and composition at different atmospheric depths

    Energy Technology Data Exchange (ETDEWEB)

    Ambriola, M.L.; Barbiellini, G.; Bartalucci, S.; Basini, G.; Bellotti, R.; Bergstroem, D.; Bocciolini, M.; Boezio, M.; Bravar, U.; Cafagna, F.; Carlson, P.; Casolino, M.; Castellano, M.; Ciacio, F.; Circella, M.; De Marzo, C.; De Pascale, M.P.; Finetti, N.; Francke, T.; Hof, M.; Kremer, J.; Menn, W.; Mitchell, J.W.; Morselli, A.; Ormes, J.F.; Papini, P.; Perego, A.; Piccardi, S.; Picozza, P.; Ricci, M.; Schiavon, P.; Simon, M.; Sparvoli, R.; Spillantini, P.; Stephens, S.A.; Stochaj, S.J.; Streitmatter, R.E.; Suffert, M.; Vacchi, A.; Weber, N.; Zampa, N

    1999-08-01

    CAPRICE98 is a superconducting magnetic spectrometer built by the WiZard collaboration. It was launched from Ft. Sumner, NM, USA on the 28th of May 1998. For the first time a gas RICH detector has been flown together with a silicon electromagnetic calorimeter. The instrument configuration included a time of flight detector and a drift chamber stack, which were placed in the region of a magnet field, for rigidity measurement. Science objectives for this experiment include the study of antimatter in cosmic rays and that of cosmic ray composition in the atmosphere with special focus on muons.

  8. 黑鳍生食金枪鱼解冻后不同气体比例气调包装的新鲜度变化%Freshness Changes of Thawed Bluefin Tuna Used for Raw Consumption during Storage in Modified Atmospheres with Different Gas Compositions

    Institute of Scientific and Technical Information of China (English)

    贡慧; 杨震; 史智佳; 刘梦; 李少鹏; 陈文华

    2016-01-01

    In this paper, we examined the effect of modified atmosphere packaging on theK value, pH value and sensory quality of thawed bluefin tuna meat during storage at 4℃. The results showed that when the modified atmosphere was CO2:N2= 60:40 (V/V), the freshness of tuna meat was preserved for the longest period of time (96 h), with no obvious acidification. Under refrigeration conditions, theK value can reflect the sensory quality of blackfin tuna meat with respect to taste and flavor.%以黑鳍金枪鱼为对象,研究4℃条件下气调包装对其K值、pH值与感官品质的影响。结果表明:当气调包装的气体比例为CO2∶N2=60∶40(V/V)时,黑鳍金枪鱼保鲜时间最久,可达到96 h,且不会发生明显酸化;在冷藏条件下,K值可以从滋味、气味的角度很好地反映黑鳍金枪鱼的感官品质。

  9. Tree growth acceleration and expansion of alpine forests: The synergistic effect of atmospheric and edaphic change.

    Science.gov (United States)

    Silva, Lucas C R; Sun, Geng; Zhu-Barker, Xia; Liang, Qianlong; Wu, Ning; Horwath, William R

    2016-08-01

    Many forest ecosystems have experienced recent declines in productivity; however, in some alpine regions, tree growth and forest expansion are increasing at marked rates. Dendrochronological analyses at the upper limit of alpine forests in the Tibetan Plateau show a steady increase in tree growth since the early 1900s, which intensified during the 1930s and 1960s, and have reached unprecedented levels since 1760. This recent growth acceleration was observed in small/young and large/old trees and coincided with the establishment of trees outside the forest range, reflecting a connection between the physiological performance of dominant species and shifts in forest distribution. Measurements of stable isotopes (carbon, oxygen, and nitrogen) in tree rings indicate that tree growth has been stimulated by the synergistic effect of rising atmospheric CO2 and a warming-induced increase in water and nutrient availability from thawing permafrost. These findings illustrate the importance of considering soil-plant-atmosphere interactions to understand current and anticipate future changes in productivity and distribution of forest ecosystems.

  10. Carbon allocation changes: an adaptive response to variations in atmospheric CO2

    Science.gov (United States)

    Harrison, Sandy; Li, Guangqi; Prentice, Iain Colin

    2016-04-01

    Given the ubiquity of nutrient constraints on primary production, an optimal carbon allocation strategy is expected to increase total below-ground allocation (fine root production and turnover, allocation to mycorrhizae and carbon exudation to the rhizophere) as atmospheric CO2 concentration increases. Conversely, below-ground allocation should be reduced when atmospheric CO2 concentrations were low, as occurred during glacial times. Using a coupled generic primary production and tree-growth model, we quantify the changes in carbon allocation that are required to explain the apparent homoeostasis of tree radial growth during recent decades and between glacial and interglacial conditions. These results suggest a resolution of the apparent paradox of continuing terrestrial CO2 uptake (a consequence of CO2 fertilization) and the widespread lack of observed enhancement of stem growth in trees. Adaptive shifts in carbon allocation are thus a key feature that should to be accounted for in models to predict tree growth and future timber harvests, as well as in large-scale ecosystem and carbon cycle models.

  11. Responses of Metabolites in Soybean Shoot Apices to Changing Atmospheric Carbon Dioxide Concentrations

    Directory of Open Access Journals (Sweden)

    Richard Sicher

    2012-01-01

    Full Text Available Soybean seedlings were grown in controlled environment chambers with CO2 partial pressures of 38 (ambient and 72 (elevated Pa. Five or six shoot apices were harvested from individual 21- to 24-day-old plants. Metabolites were analyzed by gas chromatography and, out of 21 compounds, only sucrose and fructose increased in response to CO2 enrichment. One unidentified metabolite, Unk-21.03 decreased up to 80% in soybean apices in response to elevated CO2. Levels of Unk-21.03 decreased progressively when atmospheric CO2 partial pressures were increased from 26 to 100 Pa. Reciprocal transfer experiments showed that Unk-21.03, and sucrose in soybean apices were altered slowly over several days to changes in atmospheric CO2 partial pressures. The mass spectrum of Unk-21.03 indicated that this compound likely contained both an amino and carboxyl group and was structurally related to serine and aspartate. Our findings suggested that CO2 enrichment altered a small number of specific metabolites in soybean apices. This could be an important step in understanding how plant growth and development are affected by carbon dioxide enrichment.

  12. Implications of high amplitude atmospheric CO2 fluctuations on past millennium climate change

    Science.gov (United States)

    van Hoof, Thomas; Kouwenberg, Lenny; Wagner-Cremer, Friederike; Visscher, Henk

    2010-05-01

    Stomatal frequency analysis of leaves of land plants preserved in peat and lake deposits can provide a proxy record of pre-industrial atmospheric CO2 concentration complementary to measurements in Antarctic ice cores. Stomatal frequency based CO2 trends from the USA and NW European support the presence of significant CO2 variability during the first half of the last millennium (Kouwenberg et al., 2005; Wagner et al., 2004; van Hoof et al., 2008). The timing of the most significant perturbation in the stomata records (1200 AD) is in agreement with an observed CO2 fluctuation in the D47 Antarctic ice-core record (Barnola et al., 1995; van Hoof et al., 2005). The amplitude of the stomatal frequency based CO2 changes (> 34ppmv) exceeds the maximum amplitude of CO2 variability in the D47 ice core (Proceedings of the National Academy of Sciences of the USA, v. 105, no. 41, pp. 15815-15818 Wagner F., L.L.R. Kouwenberg, T.B. van Hoof and H. Visscher 2004. Reproducibility of Holocene atmospheric CO2 records based on stomatal frequency. Quartenary Science Reviews. V. 23, pp. 1947-1954

  13. Tree growth acceleration and expansion of alpine forests: The synergistic effect of atmospheric and edaphic change

    Science.gov (United States)

    Silva, Lucas C. R.; Sun, Geng; Zhu-Barker, Xia; Liang, Qianlong; Wu, Ning; Horwath, William R.

    2016-01-01

    Many forest ecosystems have experienced recent declines in productivity; however, in some alpine regions, tree growth and forest expansion are increasing at marked rates. Dendrochronological analyses at the upper limit of alpine forests in the Tibetan Plateau show a steady increase in tree growth since the early 1900s, which intensified during the 1930s and 1960s, and have reached unprecedented levels since 1760. This recent growth acceleration was observed in small/young and large/old trees and coincided with the establishment of trees outside the forest range, reflecting a connection between the physiological performance of dominant species and shifts in forest distribution. Measurements of stable isotopes (carbon, oxygen, and nitrogen) in tree rings indicate that tree growth has been stimulated by the synergistic effect of rising atmospheric CO2 and a warming-induced increase in water and nutrient availability from thawing permafrost. These findings illustrate the importance of considering soil-plant-atmosphere interactions to understand current and anticipate future changes in productivity and distribution of forest ecosystems. PMID:27652334

  14. Land use changes and its impacts on air quality and atmospheric patterns

    Science.gov (United States)

    Freitas, E. D.; Mazzoli, C. R.; Martins, L. D.; Martins, J. A.; Carvalho, V.; Andrade, M.

    2013-05-01

    Possible modifications on atmospheric patterns and air quality caused by land use changes are discussed in this work. With the increasing interest in alternative energy sources, mainly due to the replacement of fossil fuels, large part of the Brazilian territory is being used for sugar cane cultivation. The resultant modifications in land use and some activities associated to this crop are studied with some detail through numerical modeling of the atmosphere. The same tool was applied to study the effect of surface type and emission sources over urban areas in the neighborhoods of the cultivated areas, in particular those located in the Metropolitan Area of Campinas, inside the state of São Paulo, Brazil. The main focus of this work was to identify some relationship between these two types of land use modification and its influence on the regional atmospheric circulation patterns and air quality over agricultural and urban areas affected by biomass burning and the traditional sources of pollutants, such as industries and vehicles. First, the effect of urban areas was analyzed and it was possible to identify typical patterns associated with urban heat islands, especially over the city of Campinas. In this region, air temperature differences up to 3 K were detected during night time. During the day, due to the atmospheric conditions of the studied period, this effect was not significant. Afterwards, the effect of sugar cane cultivated regions was discussed. The results show that the regions of sugar cane grow can significantly modify the surface energy fluxes, with direct consequences to the standards of local temperature and humidity and over nearby regions. Sensitivity tests were carried out during part of September, 2007, through the substitution of the sugar cane by a generic crop in the model, and show that during the day the cultivated areas can present temperatures up to 0,65 k higher than those in the case of the generic one. Throughout the dispersion module

  15. A kinetic chemistry tagging technique and its application to modelling the stable isotopic composition of atmospheric trace gases

    Directory of Open Access Journals (Sweden)

    S. Gromov

    2010-02-01

    Full Text Available Isotope composition, in many cases, holds unique information on sources, chemical modification and sinks of atmospheric trace gases. Vital to the interpretation and use of an increasing number of isotope analyses is appropriate modelling. However, the exact implementation of isotopic information is a challenge, and often studies use simplifications which limit their applicability. Here we confer a thorough isotopic extension to MECCA, a comprehensive kinetic chemistry sub-model. To this end, we devise a generic tagging technique for the kinetic chemistry mechanisms implemented as the sub-submodel MECCA-TAG. The technique constitutes a diagnostic tool that can benefit the investigation of various aspects of kinetic chemistry schemes; at the same time, the designed numerical optimisation reduces the computational effort while keeping important details unaffected. We further focus specifically on the modelling of stable isotopic composition, including the required extensions of the approach. The results of MECCA-TAG are evaluated against the reference sub-submodel MECCA-DBL, which is implicitly full-detailed, but necessarily is sub-optimal in practical applications due to its high computational demands. Furthermore, we evaluate the elaborate carbon and oxygen isotopic mechanism by simulating the multi-isotope composition of CO and other trace gases in the CAABA/MECCA box-model. The mechanism realistically simulates the oxygen isotope composition of key species resulting from the interchange with ozone and main atmospheric reservoirs, as well as the carbon isotope signature transfer. The model adequately reproduces the isotope chemistry features for CO under the limitation of the modelling domain. In particular, the mass-independently fractionated (MIF composition of CO due to reactions of ozone with unsaturated hydrocarbons (a source effect versus its intrinsic MIF enrichment induced in the removal reaction via oxidation by OH is assessed. As for

  16. Two Simulated-Smog Atmospheres with Different Chemical Compositions Produce Contrasting Mutagenicity in Salmonella.

    Science.gov (United States)

    Ozone (O3), particulate matter (PM), and nitrogen dioxide (NO2) are criteria pollutants used to evaluate air quality. Using a 14.3-m3 Teflon-lined smog chamber with 120 UV bulbs to simulate solar radiation, we generated 2 simulated-smog atmospheres (SSA-1 & SSA-2) with differ...

  17. Two Simulated-Smog Atmospheres with Different Chemical Compositions Produce Contrasting Mutagenicity in Salmonella**

    Science.gov (United States)

    Ozone (O3), particulate matter (PM), and nitrogen dioxide (NO2) are criteria pollutants used to evaluate air quality. Using EPA’s Mobile Reaction Chamber (MRC), we generated 2 simulated-smog atmospheres (SSA-1 & SSA-2) with different concentrations of these criteria pol...

  18. ISOTOPIC (14C) AND CHEMICAL COMPOSITION OF ATMOSPHERIC VOLATILE ORGANIC COMPOUND FRACTIONS - PRECURSORS TO OZONE FORMATION

    Science.gov (United States)

    Atmospheric volatile organic compounds (VOCs) are an important factor in the production of ozone near ground level [3]. Many hydrocarbons originate from auto exhaust. However, a number of VOCs, e.g., isoprene, are known to be natural in origin. To develop reliable models for un...

  19. Pacific Northwest ecosystem responses to atmospheric changes in the 21st century

    Science.gov (United States)

    De La Cruz Tello, G.; Bonan, G. B.; Lombardozzi, D.; Levis, S.

    2013-12-01

    The terrestrial carbon cycle regulates carbon pools and fluxes throughout the Earth system. Currently, the Pacific Northwest is a carbon sink; it is gaining more carbon than it is releasing into the atmosphere. Investigating changes to this carbon sink is critical for understanding ecosystem responses to future environmental change. The Community Land Model version 4 (CLM4CN) was run with eight simulations for varying atmospheric changes. Half of the simulations ran using Qian climate data for 1948-2004, and half ran with climate data for 2075-2100 from the Representative Concentration Pathways 8.5 scenario (RCP8.5). One run from each group was forced with an increased carbon dioxide (CO2) concentration of 937.87 parts per million (ppm), another was forced with an increased tropospheric ozone (O3) concentration, the third included a combination of increased O3 and CO2 concentrations, and the fourth was a control. Carbon pools decreased with the RCP8.5 scenario in all simulations. An increased CO2 concentration grew carbon pools in both climates. An increased O3 concentration had the opposite effect. A combination of O3 and CO2 showed that carbon pools increased, and the increase was smaller than with CO2 alone. Net primary production (NPP) and net ecosystem production (NEP) mirrored the carbon pool changes. Net ecosystem exchange (NEE) showed that an increased CO2 concentration increased the carbon sink in both climates. The region became a source of carbon with increased O3. The carbon sink increased with a combination of O3 and CO2, with the increase being smaller than the CO2 alone. The figure shows the changes in the ecosystem carbon pool resulting from increasing gas concentrations in various simulations. The x axis represents the future climate scenario control. The black box represents the difference between the carbon pool with increased carbon dioxide (CO2) and the control simulation. The grey box is the difference in the carbon pool between the simulation

  20. Change of the dynamics of heavy metals concentration in atmospheric precipitation in chatkal nature reservation of the republic of uzbekistan as anthropogenic index of the atmospheric pollution

    Science.gov (United States)

    Smirnova, T.; Tolkacheva, G.

    2003-04-01

    At present the investigation of the chemical composition of precipitation is a very actual task in the monitoring of environmental pollution. It is known that heavy metals can be the indices of the anthropogenic atmospheric pollution. The emissions from the mining enterprises, of non-ferrous metallurgy, of chemical industry, from heat-and-power production plants, from transport vehicles fare the sources of the heavy metals ingress into the atmosphere. Their emissions in atmosphere form fine-disperse aerosol fractions and afterwards they fall down together with precipitation onto the underlying surface. Heavy metals have the property of accumulation in environmental objects, which disturbs its ecological balance. One of the problems of the study of the influence of heavy metals pollution on the environment is their travel with the air masses of different origin on large distance. In this concern it is interesting to study the content of the heavy metals in atmospheric aerosols and precipitation in the background zones. Chatkal nature reservation on the territory of Tashkent province presents such background point. For the estimation of the level of atmospheric pollution by heavy metals and evaluation of the possible impact on the background level of air pollution of Chatkal nature reservation by anthropogenic sources (industrial cities of the capital province of Uzbekistan) the data analysis was carried out by the Administration of Environment Pollution Monitoring (AEPM) of hydrometeorological service of the Republic of Uzbekistan. It is necessary to mention that Chatkal biospheric nature reservation is situated in 100 km from Tashkent (the capital of the Republic of Uzbekistan) and in 60 km from Almalyk (the biggest centre of mining-metallurgical and chemical industry of the republic). The station of the complex background monitoring of atmospheric pollution (SCBM) is situated on the territory of this nature reservation. This area is characterized by a typical

  1. Climate change and atmospheric chemistry: how will the stratospheric ozone layer develop?

    Science.gov (United States)

    Dameris, Martin

    2010-10-25

    The discovery of the ozone hole over Antarctica in 1985 was a surprise for science. For a few years the reasons of the ozone hole was speculated about. Soon it was obvious that predominant meteorological conditions led to a specific situation developing in this part of the atmosphere: Very low temperatures initiate chemical processes that at the end cause extreme ozone depletion at altitudes of between about 15 and 30 km. So-called polar stratospheric clouds play a key role. Such clouds develop at temperatures below about 195 K. Heterogeneous chemical reactions on cloud particles initiate the destruction of ozone molecules. The future evolution of the ozone layer will not only depend on the further development of concentrations of ozone-depleting substances, but also significantly on climate change.

  2. Decadal change in the troposphere and atmospheric boundary layer over the South Pole

    Energy Technology Data Exchange (ETDEWEB)

    Neff, W.D. [National Oceanic and Atmospheric Administration/Environmental Technology Lab., Boulder, CO (United States)

    1994-12-31

    During the austral winter of 1993, the Environmental Technology Laboratory carried out a detailed field study of the atmospheric boundary layer at Amundsen-Scott South Pole Station to determine the effect of transitory synoptic disturbances on the surface-energy budget. This study used newly developed 915-megahertz radar wind-profiling technology for the first time in the Antarctic in combination with conventional boundary layer instrumentation that included a short tower, sonic anemometer, microbarograph array, and doppler sodar. Recent discussions, however, of interdecadal variability in the circumpolar circulation around Antarctica and of decadal changes in summer cloudiness at the South Pole, motivated our study of the long-term variability in boundary layer characteristics, cloudiness, and tropospheric flow behavior to provide a climatological context for our single year`s observations. 7 refs., 3 figs.

  3. A reconstruction of atmospheric carbon dioxide and its stable carbon isotopic composition from the penultimate glacial maximum to the last glacial inception

    Directory of Open Access Journals (Sweden)

    R. Schneider

    2013-11-01

    δ13Catm level in the Penultimate (~ 140 000 yr BP and Last Glacial Maximum (~ 22 000 yr BP, which can be explained by either (i changes in the isotopic composition or (ii intensity of the carbon input fluxes to the combined ocean/atmosphere carbon reservoir or (iii by long-term peat buildup. Our isotopic data suggest that the carbon cycle evolution along Termination II and the subsequent interglacial was controlled by essentially the same processes as during the last 24 000 yr, but with different phasing and magnitudes. Furthermore, a 5000 yr lag in the CO2 decline relative to EDC temperatures is confirmed during the glacial inception at the end of MIS5.5 (120 000 yr BP. Based on our isotopic data this lag can be explained by terrestrial carbon release and carbonate compensation.

  4. Climate change scenarios of extreme temperatures and atmospheric humidity for Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Tejeda-Martinez, A. [Departamento de Ciencias Atmosfericas, Universidad Veracruzana, Xalapa, Veracruz (Mexico)]. E-mail: atejeda@uv.mx; Conde-Alvarez, C. [Centro de Ciencias de la Atmosfera, Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico); Valencia-Treviso, L.E. [Departamento de Ciencias Atmosfericas, Universidad Veracruzana, Xalapa, Veracruz (Mexico)

    2008-10-15

    The following study explores climatic change scenarios of extreme temperature and atmospheric humidity for the 2020 and 2050 decades. They were created for Mexico through the GFDLR30, ECHAM4 and HadCM2 general circulation models. Base scenario conditions were associated with the normal climatological conditions for the period 1961-1990, with a database of 50 surface observatories. It was necessary to empirically estimate the missing data in approximately half of the pressure measurements. For the period 1961-1990, statistical models of the monthly means of maximum and minimum temperatures and atmospheric humidity (relative and specific) were obtained from the observed data of temperature, solar radiation and precipitation. Based on the simulations of the GFDLR30, ECHAM4 and HADCM2 models, a future scenario of monthly means of maximum and minimum temperatures and humidity in climatic change conditions was created. The results shown are for the representative months of winter (January) and summer (July). [Spanish] En este articulo se presentan escenarios de cambio climatico referidos a temperaturas extremas y humedad atmosferica para las decadas de 2020 y 2050. Fueron generados para Mexico a partir de los modelos de circulacion general GFDLR30, ECHAM4 y HADCM2. El escenario base corresponde a las normales climatologicas del periodo 1961-1990 para 50 observatorios de superficie. Para la mitad de ellos fue necesario estimar empiricamente la presion atmosferica a partir de la altitud y para la totalidad se obtuvieron modelos estadisticos de los promedios mensuales de temperaturas maxima y minima asi como de humedad atmosferica (relativa y especifica). Esos modelos estadisticos, combinados con las salidas de los modelos de circulacion general mencionados, produjeron escenarios futuros de medias mensuales de temperaturas extremas y de humedad bajo condiciones de cambio climatico. Se mostraran los resultados para un mes representativo del invierno (enero) y otro del verano

  5. Multidecadal changes in the relationship between extreme temperature events in Uruguay and the general atmospheric circulation

    Energy Technology Data Exchange (ETDEWEB)

    Renom, Madeleine; Barreiro, Marcelo [Universidad de la Republica, Unidad de Ciencias de la Atmosfera, Instituto de Fisica, Facultad de Ciencias, Montevideo (Uruguay); Rusticucci, Matilde [Universidad de Buenos Aires, Departamento de Ciencias de la Atmosfera y los Oceanos, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina)

    2011-12-15

    We analyze changes in the relationship between extreme temperature events and the large scale atmospheric circulation before and after the 1976 climate shift. To do so we first constructed a set of two temperature indices that describe the occurrence of warm nights (TN90) and cold nights (TN10) based on a long daily observed minimum temperature database that spans the period 1946-2005, and then divided the period into two subperiods of 30 years each (1946-1975 and 1976-2005). We focus on summer (TN10) and winter (TN90) seasons. During austral summer before 1976 the interannual variability of cold nights was characterized by a negative phase of the Southern Annular Mode (SAM) with a cyclonic anomaly centered off Uruguay that favoured the entrance of cold air from the south. After 1976 cold nights are associated not with the SAM, but with an isolated vortex at upper levels over South Eastern South America. During austral winter before 1976, the El Nino phenomenon dominated the interannual variability of warm nights through an increase in the northerly warm flow into Uruguay. However, after 1976 the El Nino connection weakened and the variability of warm nights is dominated by a barotropic anticyclonic anomaly located in the South Atlantic and a low pressure center over South America. This configuration also strengthens the northward flow of warm air into Uruguay. Our results suggest that changes in El Nino evolution after 1976 may have played a role in altering the relationship between temperature extreme events in Uruguay and the atmospheric circulation. (orig.)

  6. Using Atmospheric Circulation Patterns to Detect and Attribute Changes in the Risk of Extreme Climate Events

    Science.gov (United States)

    Diffenbaugh, N. S.; Horton, D. E.; Singh, D.; Swain, D. L.; Touma, D. E.; Mankin, J. S.

    2015-12-01

    Because of the high cost of extreme events and the growing evidence that global warming is likely to alter the statistical distribution of climate variables, detection and attribution of changes in the probability of extreme climate events has become a pressing topic for the scientific community, elected officials, and the public. While most of the emphasis has thus far focused on analyzing the climate variable of interest (most often temperature or precipitation, but also flooding and drought), there is an emerging emphasis on applying detection and attribution analysis techniques to the underlying physical causes of individual extreme events. This approach is promising in part because the underlying physical causes (such as atmospheric circulation patterns) can in some cases be more accurately represented in climate models than the more proximal climate variable (such as precipitation). In addition, and more scientifically critical, is the fact that the most extreme events result from a rare combination of interacting causes, often referred to as "ingredients". Rare events will therefore always have a strong influence of "natural" variability. Analyzing the underlying physical mechanisms can therefore help to test whether there have been changes in the probability of the constituent conditions of an individual event, or whether the co-occurrence of causal conditions cannot be distinguished from random chance. This presentation will review approaches to applying detection/attribution analysis to the underlying physical causes of extreme events (including both "thermodynamic" and "dynamic" causes), and provide a number of case studies, including the role of frequency of atmospheric circulation patterns in the probability of hot, cold, wet and dry events.

  7. Effects of non-thermal atmospheric pressure pulsed plasma on the adhesion and durability of resin composite to dentin.

    Science.gov (United States)

    Han, Geum-Jun; Kim, Jae-Hoon; Chung, Sung-No; Chun, Bae-Hyeock; Kim, Chang-Keun; Seo, Deog-Gyu; Son, Ho-Hyun; Cho, Byeong-Hoon

    2014-12-01

    This study investigated the effect of low-power, non-thermal atmospheric pressure plasma (NT-APP) treatments, in pulsed and conventional modes, on the adhesion of resin composite to dentin and on the durability of the bond between resin composite and dentin. A pencil-type NT-APP jet was applied in pulsed and conventional modes to acid-etched dentin. The microtensile bond strength (MTBS) of resin composite to dentin was evaluated at 24 h and after thermocycling in one control group (no plasma) and in two experimental groups (pulsed plasma and conventional plasma groups) using the Scotchbond Multi-Purpose Plus Adhesive System. Data were analyzed using two-factor repeated-measures anova and Weibull statistics. Fractured surfaces and the bonded interfaces were evaluated using a field-emission scanning electron microscope. Although there were no significant differences between the plasma treatment groups, the plasma treatment improved the MTBS compared with the control group. After thermocycling, the MTBS did not decrease in the control or conventional plasma group but increased in the pulsed plasma group. Thermocycling increased the Weibull moduli of plasma-treated groups. In conclusion, plasma treatment using NT-APP improved the adhesion of resin composite to dentin. Using a pulsed energy source, the energy delivered to the dentin was effectively reduced without any reduction in bond strength or durability.

  8. Preparation of ZrC nano-particles reinforced amorphous carbon composite coating by atmospheric pressure chemical vapor deposition

    Science.gov (United States)

    Sun, W.; Xiong, X.; Huang, B. Y.; Li, G. D.; Zhang, H. B.; Xiao, P.; Chen, Z. K.; Zheng, X. L.

    2009-05-01

    To eliminate cracks caused by thermal expansion mismatch between ZrC coating and carbon-carbon composites, a kind of ZrC/C composite coating was designed as an interlayer. The atmospheric pressure chemical vapor deposition was used as a method to achieve co-deposition of ZrC and C from ZrCl 4-C 3H 6-H 2-Ar source. Zirconium tetrachloride (ZrCl 4) powder carrier was especially made to control accurately the flow rate. The microstructure of ZrC/C composite coating was studied using analytical techniques. ZrC/C coating shows same morphology as pyrolytic carbon. Transmission electron microscopy (TEM) shows ZrC grains with size of 10-50 nm embed in turbostratic carbon. The formation mechanism is that the growth of ZrC crystals was inhibited by surrounding pyrolytic carbon and kept as nano-particles. Fracture morphologies imply good combination between coating and substrate. The ZrC crystals have stoichiometric proportion near 1, with good crystalline but no clear preferred orientation while pyrolytic carbon is amorphous. The heating-up oxidation of ZrC/C coating shows 11.58 wt.% loss. It can be calculated that the coating consists of 74.04 wt.% ZrC and 25.96 wt.% pyrolytic carbon. The average density of the composite coating is 5.892 g/cm 3 by Archimedes' principle.

  9. Changes in household composition as determinant of changes in functional ability among old men and women

    DEFF Research Database (Denmark)

    Avlund, Kirsten; Due, Pernille; Holstein, Bjørn Evald

    2002-01-01

    /21% deteriorated, 3/6% improved, and 14/14% had sustained poor function. Among the women in need of help at age 75, those who lived alone/became alone had a higher risk of sustained need for help from age 75 to 80 compared to women who lived with others [adjusted OR=4.0 (1.3-12.2/4.4 (0.7-26.9)]. This was not seen...... in functional ability are described as 1) sustained good, 2) decreased, 3) improved, and 4) sustained poor, and changes in household composition as 1) sustained living alone, 2) from living with others to living alone, and 3) sustained living with others. Number of chronic diseases and home help were included...

  10. Atmospheric teleconnections between the tropics and high southern latitudes during millennial climate change

    Science.gov (United States)

    Markle, Bradley; Steig, Eric; Schoenemann, Spruce; Buizert, Christo; Pedro, Joel; Bitz, Cecilia; Ding, Qinghua; Jones, Tyler; Fudge, Tyler

    2015-04-01

    Rapid climate changes, known as Dansgaard-Oeschger (DO) events, are ubiquitous over the last glacial period. DO climate anomalies are propagated globally through climatic teleconnections that are incompletely understood and insufficiently constrained by paleoclimatic data. Here we use a high-resolution deuterium excess record from West Antarctica to show that changes in the moisture sources for Antarctic precipitation occurred in-phase with the DO shifts in Northern Hemisphere (NH) climate and tropical hydrology. These results support the hypothesis that the Southern Hemisphere (SH) storm tracks migrate northwards during NH warm periods, in parallel with the well-established northward migration of the intertropical convergence zone. Variability in the deuterium excess record also suggests that Southern Ocean sea surface temperatures (SST) followed the pattern of Antarctic surface temperatures -- out of phase with NH climate, as expected from conceptual and numerical models of the ocean bipolar "seesaw" mechanism. Furthermore, using a physically-based definition of the deuterium excess parameter, we show East Antarctic records are highly coherent with the WAIS Divide record, indicating that the SST changes are zonally uniform. Our data demonstrate that both atmospheric and oceanic teleconnections couple climate variations between the NH and SH high latitudes, and constrain the timescales on which they operate.

  11. Stability of Atmospheric-Pressure Plasma Induced Changes on Polycarbonate Surfaces

    Science.gov (United States)

    Sharma, Rajesh; Holcomb, Edward; Trigwell, Steve

    2006-01-01

    Polycarbonate films are subjected to plasma treatment in a number of applications such as improving adhesion between polycarbonate and silicon alloy in protective and optical coatings. The changes in surface chemistry due to plasma treatment have tendency to revert back. Thus stability of the plasma induced changes on polymer surfaces over desired time period is very important. The objective of this study was to examine the effect of ageing on atmospheric pressure helium-plasma treated polycarbonate (PC) sample as a function of treatment time. The ageing effects were studied over a period of 10 days. The samples were plasma treated for 0.5, 2, 5 and 10 minutes. Contact angle measurements were made to study surface energy changes. Modification of surface chemical structure was examined using, X-ray Photoelectron Spectroscopy (XPS). Contact angle measurements on untreated and plasma treated surfaces were made immediately, 24, 48, 72 and 96 hrs after treatment. Contact angle decreased from 93 deg for untreated sample to 30 deg for sample plasma treated for 10 minutes. After 10 days the contact angles for the 10 minute plasma treated sample increased to 67 deg, but it never reverted back to that of untreated surface. Similarly the O/C ratio increased from 0.136 for untreated sample to 0.321 for 10 minute plasma treated sample indication increase in surface energy.

  12. Effect of small glass composition changes on flue gas emissions of glass furnaces

    NARCIS (Netherlands)

    Limpt, J.A.C. van; Beerkens, R.G.C.; Kersbergen, M.J. van

    2008-01-01

    Relatively small changes in glass composition might have drastic consequences on the evaporation rates of volatile glass components in glass melting furnaces. Transpiration evaporation tests have been applied to measure the impact of minor glass composition changes on the evaporation rates of volati

  13. Atmospheric Chemistry and Greenhouse Gases

    Energy Technology Data Exchange (ETDEWEB)

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

    2001-10-01

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

  14. Changes in scattering and absorption during curing of denta-resin composites: silorane and nanocomposite

    Science.gov (United States)

    del Mar Pérez, Maria; Ghinea, Razvan; Ionescu, Ana-Maria; de la Cruz Cardona, Juan

    2011-05-01

    Photocured polymers are widely used in dental applications. The optical properties of the dental composites change during curing; the appearance of the composites also changes. Recently, a new silorane-based composite resin and dental nanocomposite have been introduced. However, research regarding the effect of the silorane monomers or the size filler on appearance after curing of the resin composite is limited. This work aims to examine the optical properties of silorane-based composite and nanocomposite, in terms of scattering and absorption during curing. Six dimethacrylate-based dental resin composite (five universal and one nanocomposite) and one silorane-based dental resin composite (all shades A2 and T) were studied. The curing irradiance was 1100mW/cm2. The spectral reflectance of 1mm thick composite samples against white and black backgrounds were measured both before and after curing, and were converted to scattering and absorption coefficients using the Kubelka-Munk Theory. Both for pre and post-curing dental resin composites, the Albedo coefficient (K/S) shows that absorption prevails over the scattering for short wavelengths while for medium and large wavelengths, the scattering becomes more important, except for the T shade of the nanocomposite. After curing, the scattering and absorption values decreased for both types of materials. Changes in the absorption coefficient values should be caused by changes in the camphorquinone (CQ) absorption, whereas the scattering changes found should be directly attributable to index of refraction changes of the resin during curing.

  15. Origins and composition of fine atmospheric carbonaceous aerosol in the Sierra Nevada Mountains, California

    Directory of Open Access Journals (Sweden)

    D. R. Worton

    2011-10-01

    Full Text Available In this paper we report chemically resolved measurements of organic aerosol (OA and related tracers during the Biosphere Effects on Aerosols and Photochemistry Experiment (BEARPEX at the Blodgett Forest Research Station, California from 15 August–10 October 2007. OA contributed the majority of the mass to the fine atmospheric particles and was predominately oxygenated (OOA. The highest concentrations of OA were during sporadic wildfire influence when aged plumes were impacting the site. In situ measurements of particle phase molecular markers were dominated by secondary compounds and along with gas phase compounds could be categorized into six factors or sources: (1 aged biomass burning emissions and oxidized urban emissions, (2 oxidized urban emissions (3 oxidation products of monoterpene emissions, (4 monoterpene emissions, (5 anthropogenic emissions and (6 local methyl chavicol emissions and oxidation products. There were multiple biogenic components that contributed to OA at this site whose contributions varied diurnally, seasonally and in response to changing meteorological conditions, e.g. temperature and precipitation events. Concentrations of isoprene oxidation products were larger when temperatures were higher during the first half of the campaign (15 August–12 September due to more substantial emissions of isoprene and enhanced photochemistry. The oxidation of methyl chavicol, an oxygenated terpene emitted by ponderosa pine trees, contributed similarly to OA throughout the campaign. In contrast, the abundances of monoterpene oxidation products in the particle phase were greater during the cooler conditions in the latter half of the campaign (13 September–10 October, even though emissions of the precursors were lower, although the mechanism is not known. OA was correlated with the anthropogenic tracers 2-propyl nitrate and carbon monoxide (CO, consistent with previous observations, while being comprised of mostly non-fossil carbon

  16. Quantitative estimates of past changes in ITCZ position and cross-equatorial atmospheric heat transport

    Science.gov (United States)

    McGee, D.; Donohoe, A.; Marshall, J.; Ferreira, D.

    2012-12-01

    The mean position and seasonal migration of the Intertropical Convergence Zone (ITCZ) govern the intensity, spatial distribution and seasonality of precipitation throughout the tropics as well as the magnitude and direction of interhemispheric atmospheric heat transport (AHT). As a result of these links to global tropical precipitation and hemispheric heat budgets, paleoclimate studies have commonly sought to use reconstructions of local precipitation and surface winds to identify past shifts in the ITCZ's mean position or seasonal extent. Records indicate close ties between ITCZ position and interhemispheric surface temperature gradients in past climates, with the ITCZ shifting toward the warmer hemisphere. This shift would increase AHT into the cooler hemisphere to at least partially compensate for cooling there. Despite widespread qualitative evidence consistent with ITCZ shifts, few proxy records offer quantitative estimates of the distance of these shifts or of the associated changes in AHT. Here we present a strategy for placing quantitative limits on past changes in mean annual ITCZ position and interhemispheric AHT based on explorations of the modern seasonal cycle and models of present and past climates. We use reconstructions of tropical sea surface temperature gradients to place bounds on globally averaged ITCZ position and interhemispheric AHT during the Last Glacial Maximum, Heinrich Stadial 1, and the Mid-Holocene (6 ka). Though limited by the small number of SST records available, our results suggest that past shifts in the global mean ITCZ were small, typically less than 1 degree of latitude. Past changes in interhemispheric AHT may have been substantial, with anomalies approximately equal to the magnitude of modern interhemispheric AHT. Using constraints on the invariance of the total (ocean+atmosphere) heat transport we suggest possible bounds on fluctuations of the OHT and AMOC during Heinrich Stadial 1. We also explore ITCZ shifts in models and

  17. Sensitivity of the Reaction Mechanism of the Ozone Depletion Events during the Arctic Spring on the Initial Atmospheric Composition of the Troposphere

    Directory of Open Access Journals (Sweden)

    Le Cao

    2016-09-01

    Full Text Available Ozone depletion events (ODEs during the Arctic spring have been investigated since the 1980s. It was found that the depletion of ozone is highly associated with the release of halogens, especially bromine containing compounds. These compounds originate from various substrates such as the ice/snow-covered surfaces in Arctic. In the present study, the dependence of the mixing ratios of ozone and principal bromine species during ODEs on the initial composition of the Arctic atmospheric boundary layer was investigated by using a concentration sensitivity analysis. This analysis was performed by implementing a reaction mechanism representing the ozone depletion and halogen release in the box model KINAL (KInetic aNALysis of reaction mechanics. The ratios between the relative change of the mixing ratios of particular species such as ozone and the variation in the initial concentration of each atmospheric component were calculated, which indicate the relative importance of each initial species in the chemical kinetic system. The results of the computations show that the impact of various chemical species is different for ozone and bromine containing compounds during the depletion of ozone. It was found that CH3CHO critically controls the time scale of the complete removal of ozone. However, the rate of the ozone loss and the maximum values of bromine species are only slightly influenced by the initial value of CH3CHO. In addition, according to the concentration sensitivity analysis, the reduction of initial Br2 was found to cause a significant retardant of the ODE while the initial mixing ratio of HBr exerts minor influence on both ozone and bromine species. In addition, it is also interesting to note that the increase of C2H2 would significantly raise the amount of HOBr and Br in the atmosphere while the ozone depletion is hardly changed.

  18. Atmospheric Environment Fabrication of Composite Films by Ethanol Catalytic Combustion and Its Use as Counter Electrodes for Dye-Sensitized Soar Cells

    Directory of Open Access Journals (Sweden)

    Xiaoping Zou

    2014-01-01

    Full Text Available The composite films which consist of amorphous carbon, carbon nanotube, and iron nanoparticles were prepared by ethanol catalytic combustion in atmospheric environment. The as-prepared composite films have good electrocatalytic activity and high conductivity which is due to their particular structure. The efficiency of the composite films based dye-sensitized soar cells (DSSCs is closed to that of the Pt based one. Most importantly, the DSSC employing the composite films presents a higher FF than those of Pt based solar cell. In addition, it is a simple method for mass production of composite films counter electrode (CE which is expected to reduce the cost of fabricating DSSCs.

  19. Atmospheric composition and micro-climate in the Alhambra monument, Granada (Spain), in the context of preventive conservation

    Science.gov (United States)

    Horemans, B.; Schalm, O.; De Wael, K.; Cardell, C.; Van Grieken, R.

    2012-07-01

    The world famous Alhambra monument in Granada, Southern Spain, listed as UNESCO world cultural heritage since 1984, represents probably the most beautiful example of Islamic art and architecture from the Middle Ages in Europe. It is visited by ca. 2 million people annually. Granada is situated in a natural basin, surrounded by mountains with altitudes up to 3500 m. Due to this topography and the prevailing low wind speeds, pollution-derived and especially traffic-derived particulate matter often accumulates in the urban air. In order to evaluate the potential conservation risks from the surrounding air, the atmospheric composition in the Alhambra monument was evaluated. Indoor temperature and relative humidity fluctuations were evaluated for their potential degenerative effects. Furthermore, the atmospheric composition in the Alhambra was analyzed in terms of inorganic gases (NO2, SO2, O3, and NH3) and black carbon. It was found that the open architecture protected the indoor environments from developing a potentially harmful microclimate, such as the build-up of humidity resulting from the huge number of daily tourists. On the downside, the strong ventilation made the indoor air hardly different from outdoor air, as characterized by strong diurnal temperature and relative humidity gradients and high traffic-derived pollutant levels.

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

    Science.gov (United States)

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

    2012-12-01

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

  1. Erosion behavior of composite Al-Cr cathodes in cathodic arc plasmas in inert and reactive atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Franz, Robert, E-mail: robert.franz@unileoben.ac.at; Mendez Martin, Francisca; Hawranek, Gerhard [Montanuniversität Leoben, Franz-Josef-Strasse 18, 8700 Leoben (Austria); Polcik, Peter [Plansee Composite Materials GmbH, Siebenbürgerstrasse 23, 86983 Lechbruck am See (Germany)

    2016-03-15

    Al{sub x}Cr{sub 1−x} composite cathodes with Al contents of x = 0.75, 0.5, and 0.25 were exposed to cathodic arc plasmas in Ar, N{sub 2}, and O{sub 2} atmospheres and their erosion behavior was studied. Cross-sectional analysis of the elemental distribution of the near-surface zone in the cathodes by scanning electron microscopy revealed the formation of a modified layer for all cathodes and atmospheres. Due to intermixing of Al and Cr in the heat-affected zone, intermetallic Al-Cr phases formed as evidenced by x-ray diffraction analysis. Cathode poisoning effects in the reactive N{sub 2} and O{sub 2} atmospheres were nonuniform as a result of the applied magnetic field configuration. With the exception of oxide islands on Al-rich cathodes, reactive layers were absent in the circular erosion zone, while nitrides and oxides formed in the less eroded center region of the cathodes.

  2. Organic Aerosol Volatility Parameterizations and Their Impact on Atmospheric Composition and Climate

    Science.gov (United States)

    Tsigaridis, Konsta; Bauer, Susanne E.

    2015-01-01

    Despite their importance and ubiquity in the atmosphere, organic aerosols are still very poorly parameterized in global models. This can be explained by two reasons: first, a very large number of unconstrained parameters are involved in accurate parameterizations, and second, a detailed description of semi-volatile organics is computationally very expensive. Even organic aerosol properties that are known to play a major role in the atmosphere, namely volatility and aging, are poorly resolved in global models, if at all. Studies with different models and different parameterizations have not been conclusive on whether the additional complexity improves model simulations, but the added diversity of the different host models used adds an unnecessary degree of variability in the evaluation of results that obscures solid conclusions.

  3. Abundance and isotopic composition of gases in the martian atmosphere from the Curiosity rover

    NARCIS (Netherlands)

    Mahaffy, P.R.; Webster, C.R.; Atreya, S.K.; Franz, H.; Wong, M.; Conrad, P.G.; Harpold, D.; Jones, J.J.; Leshin, L.A.; Manning, H.; Owen, T.; Pepin, R.O.; Squyres, S.; Trainer, M.; MSL Science Team, the

    2013-01-01

    Volume mixing and isotope ratios secured with repeated atmospheric measurements taken with the Sample Analysis at Mars instrument suite on the Curiosity rover are: carbon dioxide (CO2), 0.960(±0.007); argon-40 (40Ar), 0.0193(±0.0001); nitrogen (N2), 0.0189(±0.0003); oxygen, 1.45(±0.09) × 10−3; carbo

  4. Aerosol Observability and Data Assimilation Investigations in Support of Atmospheric Composition Forecasts

    Science.gov (United States)

    2012-09-30

    aerosol model demands for such applications as joint surface-atmosphere retrievals, directed energy (DE), and intelligence, surveillance, and...C. Schmidt, J. I Miettinen, L. Giglio, (2012), Different views of fire activity over Indonesia and Malaysia from polar and geostationary...Greece, 25-29 June, 2012. Hyer, E. J., J. S. Reid, E. M. Prins, J. Hoffman, C. C. Schmidt, L. Giglio, D. A. Peterson (2011) Biomass burning observations

  5. Composition of semi-volatile organic compounds in the urban atmosphere of Singapore: influence of biomass burning

    Science.gov (United States)

    He, J.; Zielinska, B.; Balasubramanian, R.

    2010-12-01

    An intensive field study was conducted in the urban atmosphere of Singapore to investigate the composition of organic compounds in both gaseous and particulate phases during the period of August to early November 2006. 17 atmospheric samples were collected. These samples were subjected to accelerated solvent extraction with a mixture of dichloromethane and acetone and separated into functional group fractions for analyses by GC/MS. Over 180 organic compounds belonging to three major fractions (n-alkanes, polycyclic aromatic hydrocarbons - PAHs, and polar organic compounds - POCs) were identified and quantified. The characteristics and abundance of the n-alkanes, PAHs, mono and dicarboxylic acids, methoxylated phenols and other POCs were determined. The composition of these organic compounds fluctuated temporally with most of them being relatively higher in October than those in other months of the sampling period. 3-D backward air mass trajectory analyses together with the carbon preference index (CPI), molecular diagnostic ratios and molecular markers were used to investigate the origin of organic species measured in this study. Based on these diagnostic tools, the increased abundance of atmospheric organic species during October could be attributed to the occurrence of regional smoke haze episodes due to biomass burning in Indonesia. Among the POCs investigated, phthalic acid and cis-pinonic acid were abundant during October 2006. These two acids showed strong linear relationships with maximum daily ozone concentrations throughout the entire sampling period. This correlation with ozone suggested that the secondary aerosol constituents such as phthalic and cis-pinonic acids were probably formed through O3-induced photochemical transformation.

  6. Plutonium isotopes in the atmosphere of Central Europe: Isotopic composition and time evolution vs. circulation factors.

    Science.gov (United States)

    Kierepko, Renata; Mietelski, Jerzy W; Ustrnul, Zbigniew; Anczkiewicz, Robert; Wershofen, Herbert; Holgye, Zoltan; Kapała, Jacek; Isajenko, Krzysztof

    2016-11-01

    This paper reports evidence of Pu isotopes in the lower part of the troposphere of Central Europe. The data were obtained based on atmospheric aerosol fraction samples collected from four places in three countries (participating in the informal European network known as the Ring of Five (Ro5)) forming a cell with a surface area of about 200,000km(2). We compared our original data sets from Krakow (Poland, 1990-2007) and Bialystok (Poland, 1991-2007) with the results from two other locations, Prague (Czech Republic; 1997-2004) and Braunschweig (Germany; 1990-2003) to find time evolution of the Pu isotopes. The levels of the activity concentration for (238)Pu and for ((239+240))Pu were estimated to be a few and some tens of nBqm(-3), respectively. However, we also noted some results were much higher (even about 70 times higher) than the average concentration of (238)Pu in the atmosphere. The achieved complex data sets were used to test a new approach to the problem of solving mixing isotopic traces from various sources (here up to three) in one sample. Results of our model, supported by mesoscale atmospheric circulation parameters, suggest that Pu from nuclear weapon accidents or tests and nuclear burnt-up fuel are present in the air.

  7. Saturn's Titan: Surface change, ammonia, and implications for atmospheric and tectonic activity

    Science.gov (United States)

    Nelson, R. M.; Kamp, L. W.; Matson, D. L.; Irwin, P. G. J.; Baines, K. H.; Boryta, M. D.; Leader, F. E.; Jaumann, R.; Smythe, W. D.; Sotin, C.; Clark, R. N.; Cruikshank, D. P.; Drossart, P.; Pearl, J. C.; Hapke, B. W.; Lunine, J.; Combes, M.; Bellucci, G.; Bibring, J.-P.; Capaccioni, F.; Cerroni, P.; Coradini, A.; Formisano, V.; Filacchione, G.; Langevin, R. Y.; McCord, T. B.; Mennella, V.; Nicholson, P. D.; Sicardy, B.

    2009-02-01

    Titan is known to have a young surface. Here we present evidence from the Cassini Visual and Infrared Mapping Spectrometer that it is currently geologically active. We report that changes in the near-infrared reflectance of a 73,000 km 2 area on Titan (latitude 26° S, longitude 78° W) occurred between July 2004 and March of 2006. The reflectance of the area increased by a factor of two between July 2004 and March-April 2005; it then returned to the July 2004 level by November 2005. By late December 2005 the reflectance had surged upward again, establishing a new maximum. Thereafter, it trended downward for the next three months. Detailed spectrophotometric analyses suggest these changes happen at or very near the surface. The spectral differences between the region and its surroundings rule out changes in the distribution of the ices of reasonably expected materials such as H 2O, CO 2, and CH 4 as possible causes. Remarkably, the change is spectrally consistent with the deposition and removal of NH 3 frost over a water ice substrate. NH 3 has been proposed as a constituent of Titan's interior and has never been reported on the surface. The detection of NH 3 frost on the surface might possibly be explained by episodic effusive events occur which bring juvenile ammonia from the interior to the surface. If so, its decomposition would feed nitrogen to the atmosphere now and in the future. The lateral extent of the region exceeds that of active areas on the Earth (Hawaii) or Io (Loki).

  8. Recent changes and drivers of the atmospheric evaporative demand in the Canary Islands

    Science.gov (United States)

    Vicente-Serrano, Sergio M.; Azorin-Molina, Cesar; Sanchez-Lorenzo, Arturo; El Kenawy, Ahmed; Martín-Hernández, Natalia; Peña-Gallardo, Marina; Beguería, Santiago; Tomas-Burguera, Miquel

    2016-08-01

    We analysed recent evolution and meteorological drivers of the atmospheric evaporative demand (AED) in the Canary Islands for the period 1961-2013. We employed long and high-quality time series of meteorological variables to analyse current AED changes in this region and found that AED has increased during the investigated period. Overall, the annual ETo, which was estimated by means of the FAO-56 Penman-Monteith equation, increased significantly by 18.2 mm decade-1 on average, with a stronger trend in summer (6.7 mm decade-1). In this study we analysed the contribution of (i) the aerodynamic (related to the water vapour that a parcel of air can store) and (ii) radiative (related to the available energy to evaporate a quantity of water) components to the decadal variability and trends of ETo. More than 90 % of the observed ETo variability at the seasonal and annual scales can be associated with the variability in the aerodynamic component. The variable that recorded more significant changes in the Canary Islands was relative humidity, and among the different meteorological factors used to calculate ETo, relative humidity was the main driver of the observed ETo trends. The observed trend could have negative consequences in a number of water-depending sectors if it continues in the future.

  9. German Shepherd Dog Milk Composition and Its Changes During Lactation

    Directory of Open Access Journals (Sweden)

    Dokoupilová A.

    2016-03-01

    Full Text Available Milk composition of nine lactating German Shepherd nursing females was studied. The experiment took place at the breeding facility of Police of the Czech Republic (breeding centre for service dogs in Domažlice in days 2−30 of the females’ lactation. Females were given a commercial granulated feeding mixture (starter category. Canine milk samples were analyzed using an infra-red instrument MilkoScan FT 120. Calculated mean values for colostrum (day 2 postpartum and normal milk (days 4−29 postpartum were: 23.86 and 24.63% for total solids, 8.14 and 7.22% for protein, 6.04 and 5.76% for casein, 10.22 and 11.32% for fat, 3.40 and 4.48% for lactose. German Shepherd milk showed almost no variation in composition after day 4 of lactation. Differences observed between colostrum and normal milk composition were statistically insignificant but not for lactose. No significant differences in density and other composition parameters between colostrum and normal milk were identified.

  10. Tipping points? Ethnic composition change in Dutch big city neighbourhoods

    NARCIS (Netherlands)

    Ong, C.

    2014-01-01

    Micro-level studies using individual and household data have shown that residential location choices are influenced by neighbourhood ethnic composition. Using three conurbation samples in the Netherlands - Amsterdam metropolitan area, Rotterdam-The Hague metropolitan area, and the country's largest

  11. Watershed-scale changes in terrestrial nitrogen cycling during a period of decreased atmospheric nitrate and sulfur deposition

    Science.gov (United States)

    Sabo, Robert D.; Scanga, Sara E.; Lawrence, Gregory B.; Nelson, David M.; Eshleman, Keith N.; Zabala, Gabriel A.; Alinea, Alexandria A.; Schirmer, Charles D.

    2016-12-01

    Recent reports suggest that decreases in atmospheric nitrogen (N) deposition throughout Europe and North America may have resulted in declining nitrate export in surface waters in recent decades, yet it is unknown if and how terrestrial N cycling was affected. During a period of decreased atmospheric N deposition, we assessed changes in forest N cycling by evaluating trends in tree-ring δ15N values (between 1980 and 2010; n = 20 trees per watershed), stream nitrate yields (between 2000 and 2011), and retention of atmospherically-deposited N (between 2000 and 2011) in the North and South Tributaries (North and South, respectively) of Buck Creek in the Adirondack Mountains, USA. We hypothesized that tree-ring δ15N values would decline following decreases in atmospheric N deposition (after approximately 1995), and that trends in stream nitrate export and retention of atmospherically deposited N would mirror changes in tree-ring δ15N values. Three of the six sampled tree species and the majority of individual trees showed declining linear trends in δ15N for the period 1980-2010; only two individual trees showed increasing trends in δ15N values. From 1980 to 2010, trees in the watersheds of both tributaries displayed long-term declines in tree-ring δ15N values at the watershed scale (R = -0.35 and p = 0.001 in the North and R = -0.37 and p declining stream nitrate concentrations (-0.009 mg N L-1 yr-1, p = 0.02), but no change in the retention of atmospherically deposited N was observed. In contrast, nitrate yields in the South did not exhibit a trend, and the watershed became less retentive of atmospherically deposited N (-7.3% yr-1, p declines in terrestrial N availability inferred from tree-ring δ15N values do not always correspond with decreased stream nitrate export or increased retention of atmospherically deposited N.

  12. Future changes in atmospheric condition for the baiu under RCP scenarios

    Science.gov (United States)

    Okada, Y.; Takemi, T.; Ishikawa, H.

    2015-12-01

    This study focuses on atmospheric circulation fields during the baiu in Japan with global warming projection experimental data conducted using a 20-km mesh global atmospheric model (MRI-AGCM3.2) under Representative Concentration Pathways (RCP) scenarios. This model also used 4 different sea surface temperature (SST) initial conditions. Support of this dataset is provided by the Meteorological Research Institute (MRI). The baiu front indicated by the north-south gradient of moist static energy moves northward in present-day climate, whereas this northward shift in future climate simulations is very slow during May and June. In future late baiu season, the baiu front stays in the northern part of Japan even in August. As a result, the rich water vapor is transported around western Japan and the daily precipitation amount will increase in August. This northward shift of baiu front is associated with the westward expansion of the enhanced the North Pacific subtropical high (NPSH) into Japan region. However, the convective activity around northwest Pacific Ocean is inactive and is unlikely to occur convective jump (CJ). These models show that the weak trough exists in upper troposphere around Japan. Therefore, the cold advection stays in the northern part of Japan during June. In July, the front due to the strengthening of the NPSH moves northward, and then it stays until August. This feature is often found between the clustered SSTs, Cluster 2 and 3. The mean field of future August also show the inflow of rich water vapor content to Japan islands. In this model, the extreme rainfall suggested tends to almost increase over the Japan islands during future summer. This work was conducted under the Program for Risk Information on Climate Change supported by the Ministry of Education, Culture, Sports, Science, and Technology-Japan (MEXT).

  13. Response of the nitrogen isotopic composition of tree-rings following tree-clearing and land-use change.

    Science.gov (United States)

    Bukata, Andrew R; Kyser, T Kurtis

    2005-10-15

    Clear-cutting of forests affects the nitrogen cycle and the nitrogen isotopic composition of bioavailable ammonium and nitrate in the soil. Here, we have used nitrogen isotopic variations of tree-rings in red oak (Quercus rubra) and white oak (Quercus alba) as indicators of changes in the nitrogen cycle on a local scale. The delta15N values of late-wood from trees at two remnant forest stands in Ontario, Canada, that underwent large-scale tree-clearing and permanent land-use change at different times were measured. Trees from the perimeter of each stand record a marked 1.5-2.5 per thousand increase in the delta15N values of their tree-rings relative to the values in trees from the center of the stand, with the shift synchronous with the tree-clearing and land-use change. This shift was most likely due to increased rates of nitrification and nitrate leaching in the soil as a result of tree-clearing combined with permanent changes in hydrology and probable fertilizer use accompanying the change in land-use. Nitrogen concentration in tree-rings was not affected bytree-clearing and the associated change in land-use. These results indicate that changes in nitrogen cycling in forest ecosystems, whether due to climate change, land-use change, or other environmental changes (increased O3, other atmospheric pollutants, insects, etc.), can be faithfully monitored with nitrogen isotopic compositions of tree-rings and that dendrogeochemical analysis can be incorporated into studies of the effects of long-term anthropogenic effects on forest ecosystems.

  14. The atmosphere during the younger dryas.

    Science.gov (United States)

    Mayewski, P A; Meeker, L D; Whitlow, S; Twickler, M S; Morrison, M C; Alley, R B; Bloomfield, P; Taylor, K

    1993-07-09

    One of the most dramatic climate change events observed in marine and ice core records is the Younger Dryas, a return to near-glacial conditions that punctuated the last deglaciation. High-resolution, continuous glaciochemical records, newly retrieved from central Greenland, record the chemical composition of the arctic atmosphere at this time. This record shows that both the onset and the termination of the Younger Dryas occurred within 10 to 20 years and that massive, frequent, and short-term (decadal or less) changes in atmospheric composition occurred throughout this event. Changes in atmospheric composition are attributable to changes in the size of the polar atmospheric cell and resultant changes in source regions and to the growth and decay of continental biogenic source regions.

  15. A kinetic chemistry tagging technique and its application to modelling the stable isotopic composition of atmospheric trace gases

    Directory of Open Access Journals (Sweden)

    S. Gromov

    2010-08-01

    Full Text Available Isotope composition, in many cases, holds unique information on the sources, chemical modification and sinks of atmospheric trace gases. Vital to the interpretation and use of an increasing number of isotope analyses is appropriate modelling. However, the exact implementation of isotopic information in chemistry-climate models is a challenge, and often studies use simplifications which limit their applicability. Here we implement a thorough isotopic extension in MECCA, a comprehensive kinetic chemistry sub-model. To this end, we devise a generic tagging technique for the kinetic chemistry mechanisms implemented as the sub-submodel MECCA-TAG. The technique is diagnostic and numerically efficient and supports the investigation of various aspects of kinetic chemistry schemes. We focus specifically on the application to the modelling of stable isotopic composition. The results of MECCA-TAG are evaluated against the reference sub-submodel MECCA-DBL, which is implicitly full-detailed, but computationally expensive and thus sub-optimal in practical applications. Furthermore, we evaluate the elaborate carbon and oxygen isotopic mechanism by simulating the multi-isotope composition of CO and other trace gases in the CAABA/MECCA box-model. The mechanism realistically simulates the oxygen isotope composition of key species, as well as the carbon isotope signature transfer. The model adequately reproduces the isotope chemistry features for CO, taking into account the limits of the modelling domain. In particular, the mass-independently fractionated (MIF composition of CO due to reactions of ozone with unsaturated hydrocarbons (a source effect versus its intrinsic MIF enrichment induced in the removal reaction via oxidation by OH is assessed. The simulated ozone source effect was up to +1‰ in Δ17O(CO. The versatile modelling framework we employ (the Modular Earth Submodel System, MESSy opens the way for implementation of the novel detailed

  16. Modelling the impact of climate change and atmospheric N deposition on French forests biodiversity.

    Science.gov (United States)

    Rizzetto, Simon; Belyazid, Salim; Gégout, Jean-Claude; Nicolas, Manuel; Alard, Didier; Corcket, Emmanuel; Gaudio, Noémie; Sverdrup, Harald; Probst, Anne

    2016-06-01

    A dynamic coupled biogeochemical-ecological model was used to simulate the effects of nitrogen deposition and climate change on plant communities at three forest sites in France. The three sites had different forest covers (sessile oak, Norway spruce and silver fir), three nitrogen loads ranging from relatively low to high, different climatic regions and different soil types. Both the availability of vegetation time series and the environmental niches of the understory species allowed to evaluate the model for predicting the composition of the three plant communities. The calibration of the environmental niches was successful, with a model performance consistently reasonably high throughout the three sites. The model simulations of two climatic and two deposition scenarios showed that climate change may entirely compromise the eventual recovery from eutrophication of the simulated plant communities in response to the reductions in nitrogen deposition. The interplay between climate and deposition was strongly governed by site characteristics and histories in the long term, while forest management remained the main driver of change in the short term.

  17. Mechanical Properties of Double-Layer and Graded Composite Coatings of YSZ Obtained by Atmospheric Plasma Spraying

    Science.gov (United States)

    Carpio, Pablo; Rayón, Emilio; Salvador, María Dolores; Lusvarghi, Luca; Sánchez, Enrique

    2016-04-01

    Double-layer and graded composite coatings of yttria-stabilized zirconia were sprayed on metallic substrates by atmospheric plasma spray. The coating architecture was built up by combining two different feedstocks: one micro- and one nanostructured. Microstructural features and mechanical properties (hardness and elastic modulus) of the coatings were determined by FE-SEM microscopy and nanoindentation technique, respectively. Additional adherence and scratch tests were carried out in order to assess the failure mechanisms occurring between the layers comprising the composites. Microstructural inspection of the coatings confirms the two-zone microstructure. This bimodal microstructure which is exclusive of the layer obtained from the nanostructured feedstock negatively affects the mechanical properties of the whole composite. Nanoindentation tests suitably reproduce the evolution of mechanical properties through coatings thickness on the basis of the position and/or amount of nanostructured feedstock used in the depositing layer. Adhesion and scratch tests show the negative effect on the coating adhesion of layer obtained from the nanostructured feedstock when this layer is deposited on the bond coat. Thus, the poor integrity of this layer results in lower normal stresses required to delaminate the coating in the adhesion test as well as minor critical load registered by using the scratch test.

  18. A high resolution record of atmospheric carbon dioxide and its stable carbon isotopic composition from the penultimate glacial maximum to the glacial inception

    Directory of Open Access Journals (Sweden)

    R. Schneider

    2013-04-01

    Full Text Available The reconstruction of the stable carbon isotope evolution in atmospheric CO2 (δ13Catm, as archived in Antarctic ice cores, bears the potential to disentangle the contributions of the different carbon cycle fluxes causing past CO2 variations. Here we present a highly resolved record of δ13Catm before, during and after the Marine Isotope Stage 5.5 (155 000 to 105 000 yr BP. The record was derived with a well established sublimation method using ice from the EPICA Dome C (EDC and the Talos Dome ice cores in East Antarctica. We find an 0.4‰ offset between the mean δ13Catm level in the Penultimate (~140 000 yr BP and Last Glacial Maximum (~22 000 yr BP, which can be explained by either (i changes in the isotopic composition or (ii intensity of the carbon input fluxes to the combined ocean/atmosphere carbon reservoir or (iii by long-term peat buildup. Our isotopic data suggest that the carbon cycle evolution along Termination II and the subsequent interglacial was controlled by essentially the same processes as during the last 24 000 yr, but with different phasing and magnitudes. Furthermore, a 5000 yr lag in the CO2 decline relative to EDC temperatures is confirmed during the glacial inception at the end of MIS 5.5 (120 000 yr BP. Based on our isotopic data this lag can be explained by terrestrial carbon release and carbonate compensation.

  19. Atmospheric-Pressure Cold Plasma Induces Transcriptional Changes in Ex Vivo Human Corneas.

    Directory of Open Access Journals (Sweden)

    Umberto Rosani

    Full Text Available Atmospheric pressure cold plasma (APCP might be considered a novel tool for tissue disinfection in medicine since the active chemical species produced by low plasma doses, generated by ionizing helium gas in air, induces reactive oxygen species (ROS that kill microorganisms without substantially affecting human cells.In this study, we evaluated morphological and functional changes in human corneas exposed for 2 minutes (min to APCP and tested if the antioxidant n-acetyl l-cysteine (NAC was able to inhibit or prevent damage and cell death.Immunohistochemistry and western blotting analyses of corneal tissues collected at 6 hours (h post-APCP treatment demonstrated no morphological tissue changes, but a transient increased expression of OGG1 glycosylase that returned to control levels in 24 h. Transcriptome sequencing and quantitative real time PCR performed on different corneas revealed in the treated corneas many differentially expressed genes: namely, 256 and 304 genes showing expression changes greater than ± 2 folds in the absence and presence of NAC, respectively. At 6 h post-treatment, the most over-expressed gene categories suggested an active or enhanced cell functioning, with only a minority of genes specifically concerning oxidative DNA damage and repair showing slight over-expression values (<2 folds. Moreover, time-related expression analysis of eight genes up-regulated in the APCP-treated corneas overall demonstrated the return to control expression levels after 24 h.These findings of transient oxidative stress accompanied by wide-range transcriptome adjustments support the further development of APCP as an ocular disinfectant.

  20. Uncertainties in Projecting Future Changes in Atmospheric Rivers and Their Impacts on Heavy Precipitation over Europe

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Yang; Lu, Jian; Leung, L. Ruby

    2016-09-01

    This study investigates the North Atlantic atmospheric rivers (ARs) making landfall over western Europe in the present and future climate from the multi-model ensemble of the Coupled Model Intercomparison Project Phase 5 (CMIP5). Overall, CMIP5 captures the seasonal and spatial variations of historical landfalling AR days, with the large inter-model variability strongly correlated with the inter-model spread of historical jet position. Under RCP 8.5, AR frequency is projected to increase a few times by the end of this century. While thermodynamics plays a dominate role in the future increase of ARs, wind changes associated with the midlatitude jet shifts also significantly contribute to AR changes, resulting in dipole change patterns in all seasons. In the North Atlantic, the model projected jet shifts are strongly correlated with the simulated historical jet position. As models exhibit predominantly equatorward biases in the historical jet position, the large poleward jet shifts reduce AR days south of the historical mean jet position through the dynamical connections between the jet positions and AR days. Using the observed historical jet position as an emergent constraint, dynamical effects further increase AR days in the future above the large increases due to thermodynamical effects. In the future, both total and extreme precipitation induced by AR contribute more to the seasonal mean and extreme precipitation compared to present primarily because of the increase in AR frequency. While AR precipitation intensity generally increases more relative to the increase in integrated vapor transport, AR extreme precipitation intensity increases much less.

  1. Exploring the Interactions among Beetle-induced Changes in Catchment-scale Ecohydrology, Land Surface Fluxes and the Lower Atmosphere with a Coupled Hydrology-Atmospheric Model.

    Science.gov (United States)

    Forrester, M. M.; Maxwell, R. M.; Bearup, L. A.; Gochis, D.; Porter, A.

    2015-12-01

    The mountain pine beetle has dramatically altered ecohydrologic processes of lodgepole pine forests in western North America, having caused one of the largest insect-driven tree mortalities in recorded history. Documented and modeled responses to forest mortality include cessation of overstory transpiration, local increases in soil moisture, changes in snow accumulation and ablation, differences in groundwater and runoff contributions to streamflow, changes in sensible and latent heat partitioning, and higher surface temperatures and ground evaporation. However, the scale-sensitivity, spatial variability and interdependence of these responses, and the simultaneous process of forest recovery, mean that watershed response to infestation is often inconsistent and damped at large scales, making it difficult to capture individual hydrologic and energy components of disturbance. This study resolves complicated feedbacks from disturbance at the land surface to responses in the atmosphere with the use of the physically-based, integrated hydrologic model ParFlow, coupled to the Weather Research and Forecasting (WRF) atmospheric model. The model domain, constructed at 1-km resolution, encompasses a 25,200 square kilometer region over a Rocky Mountain headwaters catchment in Colorado. Land use and vegetation parameters within WRF were adjusted in a detailed ensemble approach to reflect beetle-induced reductions in stomatal conductivity and LAI. Results show spatially variable but generally increased soil moisture and water yield with infestation. Subsequent disturbance of the sensible and latent heat balance propagates into the atmosphere, influencing atmospheric moisture, stability and even precipitation. This work presents the applicability of a deterministic, integrated climate-hydrologic model to identify complicated physical interactions occurring with forest disturbance, which may not be discernable with simpler models or observations.

  2. Vegetation change impacts on soil organic carbon chemical composition in subtropical forests

    Science.gov (United States)

    Guo, Xiaoping; Meng, Miaojing; Zhang, Jinchi; Chen, Han Y. H.

    2016-07-01

    Changes in the chemical composition of soil organic carbon (SOC) might strongly affect the global carbon cycle as it controls the SOC decomposition rate. Vegetation change associated with long-term land use changes is known to strongly impact the chemical composition of SOC; however, data on the impacts of vegetation change following disturbance events of short durations and succession that occur frequently in forest ecosystems via diverse management objectives on SOC chemical composition are negligible. Here we examined the impacts of vegetation changes on the chemical composition of SOC by sampling soils of native broad-leaved forests, planted mixed broad-leaved and coniferous forests, and tea gardens in eastern China. We used nuclear magnetic resonance spectroscopy to quantify SOC chemical composition. We found that among all components of SOC chemical composition, alkyl carbon (C) and aryl C were more liable to change with vegetation than other SOC components. Soil pH was negatively correlated to the relative abundances of alkyl C and N-alkyl C, and Shannon’s index of overstory plant species was positively correlated to the relative abundances of phenolic C and aromaticity. Our results suggest that vegetation changes following short disturbance events and succession may strongly alter SOC chemical composition in forest ecosystems.

  3. Changes in the subgingival biofilm composition after coronally positioned flap

    Directory of Open Access Journals (Sweden)

    Jadson Almeida Lima

    2011-02-01

    Full Text Available OBJECTIVES: This study evaluated the effects of coronally positioned flap (CPF on the subgingival biofilm composition. MATERIAL AND METHODS: Twenty-two subjects with gingival recessions were treated with CPF. Clinical parameters were assessed before and at 6 months after surgery. Subgingival biofilms were analyzed by checkerboard DNA-DNA hybridization technique for 40 bacterial species. RESULTS: Recession height, clinical attachment level and bleeding on probing improved significantly (p<0.05 at 6 months post-CPF. The proportions of 10 periodontal pathogens and the proportions of red and orange complexes decreased at 6 months. CONCLUSION: In conclusion, CPF can induce beneficial effects on the composition of the subgingival microbiota after 6 months.

  4. The effect of atmosphere composition in plasma nitrogenation of Sm{sub 2}Fe{sub 17}

    Energy Technology Data Exchange (ETDEWEB)

    Ardisson, J.D. E-mail: jdr@cdtn.br; Araujo, R.C.; Macedo, W.A.A.; Persiano, A.I.C.; Gama, S

    2004-05-01

    The change on the structural and magnetic properties of the Sm{sub 2}Fe{sub 17} compound as the ratio of H{sub 2}/N{sub 2} forming the mixture of the atmosphere in a plasma chamber used to nitride this compound varied, was investigated by Moessbauer spectroscopy and X-ray diffraction. Our results show that the increase of the hydrogen concentration in the mixed H{sub 2}/N{sub 2} atmosphere reduces the formation of the nitrogen-rich phases, Sm{sub 2}Fe{sub 17}N{sub 8} and Sm{sub 2}Fe{sub 17}N{sub 11} and increases the formation of the Sm{sub 2}Fe{sub 17}N{sub 3} phase, whose maximum values are obtained for 70% H{sub 2} in the gas mixture.

  5. Porous MgO material with ultrahigh surface area as the matrix for phase change composite

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Yonggan; Shao, Xiankun; Liu, Tongxuan [School of Materials Science and Engineering, Anhui University of Science and Technology, Huainan, Anhui 232001 (China); Li, Benxia, E-mail: libx@mail.ustc.edu.cn [School of Materials Science and Engineering, Anhui University of Science and Technology, Huainan, Anhui 232001 (China); Nie, Shibin, E-mail: nsb@mail.ustc.edu.cn [School of Energy Resources and Safety, Anhui University of Science and Technology, Huainan, Anhui 232001 (China)

    2015-03-20

    Highlights: • Porous MgO material with ultrahigh surface area was synthesized. • A composite PCM was prepared from PEG-1000 and the porous MgO. • The phase change temperatures and enthalpy of the composite were measured. • The composite PCM performed good shape-stabilized property. - Abstract: Mesoporous magnesium oxide (MgO) material was synthesized using an integration of the evaporation-induced surfactant assembly and magnesium nitrate pyrolysis. The as-prepared MgO material is well crystalline, and possesses three-dimensional interconnected mesopores and a surface area as high as 596 m{sup 2}/g. Using the porous MgO as a matrix and polyethylene glycol (PEG-1000) as the functional phase for heat energy storage, a shape-stabilized phase change composite of PEG/MgO was fabricated by an easy impregnation method. In the composite, mesoporous MgO material provides structural strength and prevents the leakage of the molten PEG during the phase change process. The compositions and microstructures of the PEG/MgO composite were determined by Fourier transformation infrared spectroscope (FT-IR), X-ray diffractometer (XRD), scanning electronic microscope (SEM) and thermogravimetric analyzer (TGA), respectively. The phase change properties of the PEG/MgO composite were determined by differential scanning calorimeter (DSC). The high heat-energy storage capability and good thermal stability of the composite enable it extensive applications in the future.

  6. On the role of atmosphere-ocean interactions in the expected long-term changes of the Earth's ozone layer caused by greenhouse gases

    Science.gov (United States)

    Zadorozhny, Alexander; Dyominov, Igor

    It is well known that anthropogenic emissions of greenhouse gases into the atmosphere produce a global warming of the troposphere and a global cooling of the stratosphere. The expected stratospheric cooling essentially influences the ozone layer via increased polar stratospheric cloud formation and via temperature dependences of the gas phase reaction rates. One more mechanism of how greenhouse gases influences the ozone layer is enhanced water evaporation from the oceans into the atmosphere because of increasing temperatures of the ocean surface due to greenhouse effect. The subject of this paper is a study of the influence of anthropogenic pollution of the atmosphere by the greenhouse gases CO2, CH4, N2O and ozone-depleting chlorine and bromine compounds on the expected long-term changes of the ozone layer with taking into account an increase of water vapour content in the atmosphere due to greenhouse effect. The study based on 2-D zonally averaged interactive dynamical radiative-photochemical model of the troposphere and stratosphere. The model allows to self-consistently calculating diabatic circulation, temperature, gaseous composition of the troposphere and stratosphere at latitudes from the South to North Poles, as well as distribution of sulphate aerosol particles and polar stratospheric clouds of two types. It was supposed in the model that an increase of the ocean surface temperature caused by greenhouse effect is similar to calculated increase of atmospheric surface temperature. Evaporation rate from the ocean surface was computed in dependence of latitude. The model time-dependent runs were made for the period from 1975 to 2100 using two IPCC scenarios depicting maximum and average expected increases of greenhouse gases in the atmosphere. The model calculations show that anthropogenic increasing of water vapour abundance in the atmosphere due to heating of the ocean surface caused by greenhouse effect gives a sensible contribution to the expected ozone

  7. Hydrogen Isotopic Composition of Water in the Martian Atmosphere and Released from Rocknest Fines

    Science.gov (United States)

    Leshin, L. A.; Webster, C. R.; Mahaffy, P. R.; Flesh, G. J.; Christensen, L. E.; Stern, J. C.; Franz, H. B.; McAdam, A. C.; Niles, P. B.; Archer, P. B., Jr.; Sutter, B.; Jones, J. H.; Ming, D. W.; Atreya, S. K.; Owen, T. C.; Conrad, P.

    2013-01-01

    The Mars Science Laboratory Curiosity rover sampled the aeolian bedform called Rocknest as its first solid samples to be analyzed by the analytical instruments CheMin and SAM. The instruments ingested aliquots from a sieved sample of less than 150 micrometer grains. As discussed in other reports at this conference [e.g., 1], CheMin discovered many crystalline phases, almost all of which are igneous minerals, plus some 10s of percent of x-ray amorphous material. The SAM instrument is focused on understanding volatiles and possible organics in the fines, performing evolved gas analysis (EGA) with the SAM quadrapole mass spectrometer (QMS), isotope measurements using both the QMS and the tunable laser spectrometer (TLS), which is sensitive to CO2, water and methane, and organics with the gas chromatograph mass spectrometer (GCMS). As discussed in the abstract by Franz et al. [2] and others, EGA of Rocknest fines revealed the presence of significant amounts of H2O as well as O-, C- and S-bearing materials. SAM has also tasted the martian atmosphere several times, analyzing the volatiles in both the TLS and QMS [e.g., 3,4]. This abstract will focus on presentation of initial hydrogen isotopic data from the TLS for Rocknest soils and the atmosphere, and their interpretation. Data for CO2 isotopes and O isotopes in water are still being reduced, but should be available by at the conference.

  8. Optical phase curves as diagnostics for aerosol composition in exoplanetary atmospheres

    CERN Document Server

    Oreshenko, Maria; Demory, Brice-Olivier

    2016-01-01

    Optical phase curves have become one of the common probes of exoplanetary atmospheres, but the information they encode has not been fully elucidated. Building on a diverse body of work, we upgrade the Flexible Modeling System (FMS) to include scattering in the two-stream, dual-band approximation and generate plausible, three-dimensional structures of irradiated atmospheres to study the radiative effects of aerosols or condensates. In the optical, we treat the scattering of starlight using a generalisation of Beer's law that allows for a finite Bond albedo to be prescribed. In the infrared, we implement the two-stream solutions and include scattering via an infrared scattering parameter. We present a suite of four-parameter general circulation models for Kepler-7b and demonstrate that its climatology is expected to be robust to variations in optical and infrared scattering. The westward and eastward shifts of the optical and infrared phase curves, respectively, are shown to be robust outcomes of the simulation...

  9. Small- and medium-scale effects of high-flying aircraft exhausts on the atmospheric composition

    Directory of Open Access Journals (Sweden)

    Y. E. Ozolin

    Full Text Available Following numerous model studies of the global impacts of sub- and supersonic aircraft on the atmosphere, this paper assesses the separate aircraft engine exhaust effects of the 45°N cruise flight and at the 10- and 18-km levels of the July atmosphere. A box diffusion photochemical model in the cross-section plane of the flight trajectory is used to compute the effects of gas-phase and heterogeneous reactions on the condensation trail particles in the troposphere, and on the sulphate aerosols in the stratosphere. The enhanced horizontal dispersion of the exhaust plume is considered in the model. A significant but short term depletion of ozone is predicted, which is 99% restored in about 1 h in the wide plume with enhanced horizontal dispersion, but requires more than 24 h in the narrow plume without it. The oxidation rate of NO and NO2 into the HNO3 depends on the OH content in the exhausts and varies in all the cases. The heterogeneous photochemistry has only a small influence on the initial evolution of N2O5 and HO2 in the plume.

  10. Response of Atmospheric Energy to Historical Climate Change in CMIP5

    Institute of Scientific and Technical Information of China (English)

    韩博; 吕世华; 高艳红; 奥银焕; 李瑞青

    2015-01-01

    Three forms of atmospheric energy, i.e., internal, potential, and latent, are analyzed based on the histor-ical simulations of 32 Coupled Model Intercomparison Project Phase 5 (CMIP5) models and two reanalysis datasets (NCEP/NCAR and ERA-40). The spatial pattern of climatological mean atmospheric energy is well reproduced by all CMIP5 models. The variation of globally averaged atmospheric energy is similar to that of surface air temperature (SAT) for most models. The atmospheric energy from both simulation and reanalysis decreases following the volcanic eruption in low-latitude zones. Generally, the climatological mean of simulated atmospheric energy from most models is close to that obtained from NCEP/NCAR, while the simulated atmospheric energy trend is close to that obtained from ERA-40. Under a certain variation of SAT, the simulated global latent energy has the largest increase ratio, and the increase ratio of potential energy is the smallest.

  11. Long-term changes in atmospheric electrical parameters observed at Nagycenk (Hungary and the UK observatories at Eskdalemuir and Kew

    Directory of Open Access Journals (Sweden)

    F. Märcz

    Full Text Available The Nagycenk Geophysical Observatory in Hungary (47° 38 ' N, 16° 43 ' E has made continuous measurements of the vertical atmospheric electric Potential Gradient (PG since 1962. Global signals have previously been identified in the Nagycenk PG data. A long-term (1920–1981 decrease has been discovered in the PG measured at the Eskdalemuir Observatory, Scotland (55° 19 ' N, 3° 12 ' W, suggesting that this represents a global change in the atmospheric electricity related to a decline in cosmic rays. A 40% decline in PG is shown here to have occurred at Nagycenk between 1962 and 2001, also consistent with changes in the air-Earth current measured at Kew (51° 28 ' N, 0° 19 ' W, London, 1966–1978. Comparison of the long-term PG measurements at both Eskdalemuir and Nagycenk gives further evidence to support the hypothesis of a global atmospheric electrical decline from the early twentieth century to the present time, as it is shown that local effects at Nagycenk are unlikely to have dominated the changes there.

    Key words. Meteorology and atmospheric dynamics (atmospheric electricity

  12. Following changes in total number of mesophilic bacteria and torry meter readings in samples of fresh trout packaged in modified atmosphere and vacuum

    Directory of Open Access Journals (Sweden)

    Milijašević Milan

    2011-01-01

    Full Text Available Today, food must be healthy, subjected to minimal processing, and attractively packaged, as the expectations of consumers are ever higher. Consumers are highly sensitive to the use of additives in the food industry. There is a constant demand for fresh food that does not contain any unnecessarily added chemicals. In order to prevent spoilage of food items, an efficient and intelligent concept for preserving freshness has been developed - packaging in a modified atmosphere. Changes in a certain composition of the atmosphere within the packaging have resulted in a longer shelf life and a satisfactory quality of the food articles. Modified atmosphere packaging (MAP is well-known and has been applied in practice in the food processing industry for more than one century. The objective of these investigations was to determine the growth of the total number of mesophilic bacteria in the meat of trout packaged in a vacuum and a modified atmosphere and torry meter reading results due to changes in the dielectric characteristics of the skin that take place during the period of storage of the fresh fish. California trout (Oncorhynchus mykiss with an average weight of 293 g was used for the experimental part of the investigations. Four groups of fish samples were set up for the research. The first three groups of samples were packaged in a modified atmosphere with a different ratio of gases: Group I - 60%CO2+40%N2; Group II - 40%CO2+60%N2; Group III - 90%CO2+10%N2. Group IV comprised samples packaged in a vacuum. Investigations were carried out on days 0, 7, 14, and 21 of storage. The total number of mesophilic bacteria in the examined samples was determined according to the method ISO 4833. Measurements of changes in the dielectric characteristics of the fish skin were performed using a torry meter apparatus (The Torry Fish Freshness Meter. The results have shown that packaging of fresh trout in a modified atmosphere (60% CO2 + 40% N2 and 40% CO2 + 60% N2

  13. Effects of the annealing temperature and atmosphere on the microstructures and dielectric properties of ZnO/Al{sub 2}O{sub 3} composite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Ping, E-mail: pingwei0202@126.com; Zhu, Dongmei; Huang, Shanshan; Zhou, Wancheng; Luo, Fa

    2013-11-15

    ZnO/Al{sub 2}O{sub 3} composite coatings were fabricated by atmospheric plasma spraying technology (APS). The effects of annealing temperature and atmospheres (in air or vacuum) on the microstructure and phase transformation of the sprayed coatings were studied by scanning electron microscope (SEM) and X-ray diffraction spectroscopy (XRD). The microwave dielectric properties of these coatings after annealing treatment were also discussed in the frequency range of 8.2–12.4 GHz. Both the real part and the imaginary part of the permittivity decreased significantly with increased annealing temperature when the annealing process is carried out in air atmosphere, while the complex permittivity of the coating annealed in vacuum atmosphere was obviously increased compared to the initial sprayed coating. The mechanism for the variation of dielectric properties of sprayed ZnO/Al{sub 2}O{sub 3} composite coating caused by annealing treatment was discussed in this study.

  14. Preparation and Properties of Paraffin/TiO2/Active-carbon Composite Phase Change Materials

    Directory of Open Access Journals (Sweden)

    HAO Yong-gan

    2016-11-01

    Full Text Available A novel composite phase change materials (PCMs of paraffin/TiO2/active-carbon was prepared by a microemulsion method, where paraffin acted as a PCM and titanium dioxide (TiO2 as matrix material, and a small amount of active carbon was added to improve the thermal conductivity. The compositions, morphology and thermal properties of the paraffin/TiO2/active-carbon composite PCMs were characterized by XRD, SEM, TGA and DSC respectively. The shape stability during phase change process of this composite was also tested. The results show that paraffin is well encapsulated by TiO2 matrix, and thus exhibiting excellent shape-stabilized phase change feature. Besides, this composite PCM also presents superhydrophobic property. Therefore, these multifunctional features will endow PCMs with important application potential in energy efficient buildings.

  15. Carbon Flux to the Atmosphere from Land-Use Changes: 1850 to 1990

    Energy Technology Data Exchange (ETDEWEB)

    Houghton, R.A.

    2001-02-22

    The database documented in this numeric data package, a revision to a database originally published by the Carbon Dioxide Information Analysis Center (CDIAC) in 1995, consists of annual estimates, from 1850 through 1990, of the net flux of carbon between terrestrial ecosystems and the atmosphere resulting from deliberate changes in land cover and land use, especially forest clearing for agriculture and the harvest of wood for wood products or energy. The data are provided on a year-by-year basis for nine regions (North America, South and Central America, Europe, North Africa and the Middle East, Tropical Africa, the Former Soviet Union, China, South and Southeast Asia, and the Pacific Developed Region) and the globe. Some data begin earlier than 1850 (e.g., for six regions, areas of different ecosystems are provided for the year 1700) or extend beyond 1990 (e.g., fuelwood harvest in South and Southeast Asia, by forest type, is provided through 1995). The global net flux during the period 1850 to 1990 was 124 Pg of carbon (1 petagram = 10{sup 15} grams). During this period, the greatest regional flux was from South and Southeast Asia (39 Pg of carbon), while the smallest regional flux was from North Africa and the Middle East (3 Pg of carbon). For the year 1990, the global total net flux was estimated to be 2.1 Pg of carbon.

  16. Effects of surface modification by atmospheric oxygen dielectric barrier discharge plasma on PBO fibers and its composites

    Science.gov (United States)

    Liu, Zhe; Chen, Ping; Zhang, Xiaoliang; Yu, Qi; Ma, Keming; Ding, Zhenfeng

    2013-10-01

    In this paper, oxygen dielectric barrier discharge (oxy-DBD) plasma was employed to modify PBO fibers and enhance the interfacial adhesion of PBO fiber/bismaleimide composites. The interlaminar shear strength (ILSS) of the composites was improved greatly to 62.0 MPa with an increment of 41.2% at 30 W/cm3, 24 s. The SEM images of fracture morphology indicated that the failure place shifted from the interface to the matrix, and the water absorption decreased from 1.96 to 1.53%, the two results demonstrated the improved adhesive strength in other ways. In addition, the ILSS retention ratio of PBO/BMI composites after boiling in water were about 90%, confirming good humid resistance of the composites. The results obtained from XPS and AFM revealed that some polar groups were introduced onto PBO fibers and the surface morphology of PBO fibers was roughened. As a result, the wettability, reactivity and roughness of PBO fibers were all improved, they contributed to the improvement of the ILSS of the composites. The comparisons with air-DBD plasma showed that the chemical changes of PBO fibers were not alike because of different plasma gases.

  17. Studies of Emissions and Atmospheric Composition, Clouds, and Climate Coupling by Regional Surveys (SEAC4RS) Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Schmid, B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Flynn, C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-03-01

    Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS), a National Aeronautics and Space Administration (NASA) field campaign, was based out of Ellington Field in Houston, Texas, during August and September 2013. The study focused on pollution emissions and the evolution of gases and aerosols in deep convective outflow, and the influences and feedbacks of aerosol particles from anthropogenic pollution and biomass burning on meteorology, clouds, and climate. The project required three aircraft to accomplish these goals. The NASA DC-8 provided observations from near the surface to 12 km, while the NASA ER-2 provided high-altitude observations reaching into the lower stratosphere as well as important remote-sensing observations connecting satellites with observations from lower-flying aircraft and surface sites. The SPEC, Inc. Learjet obtained aerosol and cloud microphysical measurement in convective clouds and convective outflow.

  18. Physical changes associated with gamma doses on Wood/ Polypropylene Composites

    Science.gov (United States)

    Ndiaye, Diène; Tidjani, Adams

    2014-08-01

    The effect of gamma- radiation on the morphology, thermal behavior and mechanical properties of wood polypropylene composites has been investigated. Simultaneous thermo gravimetric analysis (TGA) and differential scanning calorimetry (DSC) have been performed on WPC samples of (9.5 ± 0.1) mg. These samples were exposed to different gamma-dose in the range 10 to 100kGy. The results indicated that gamma radiation improves the mechanical properties while the thermal stability is decreased. With gamma radiation, the scanning electron microscopy (SEM) of the micrographs became smoother and we can notice an improvement of interaction between polymer and wood fibers.

  19. Carbon-13 isotope composition of the mean CO2 source in the urban atmosphere of Krakow, southern Poland

    Science.gov (United States)

    Zimnoch, Miroslaw; Jasek, Alina; Rozanski, Kazimierz

    2014-05-01

    Quantification of carbon emissions in urbanized areas constitutes an important part of the current research on the global carbon cycle. As the carbon isotopic composition of atmospheric carbon dioxide can serve as a fingerprint of its origin, systematic observations of δ13CO2 and/or Δ14CO2, combined with atmospheric CO2mixing ratio measurements can be used to better constrain the urban sources of this gas. Nowadays, high precision optical analysers based on absorption of laser radiation in the cavity allow a real-time monitoring of atmospheric CO2 concentration and its 13CO2/12CO2 ratio, thus enabling better quantification of the contribution of different anthropogenic and natural sources of this gas to the local atmospheric CO2load. Here we present results of a 2-year study aimed at quantifying carbon isotopic signature of the mean CO2 source and its seasonal variability in the urban atmosphere of Krakow, southern Poland. The Picarro G2101-i CRDS isotopic analyser system for CO2and 13CO2/12CO2 mixing ratio measurements has been installed at the AGH University of Science and Technology campus in July 2011. Air inlet was located at the top of a 20m tower mounted on the roof of the faculty building (ca. 42m a.g.l.), close to the city centre. While temporal resolution of the analyser is equal 1s, a 2-minute moving average was used for calculations of δ13CO2 and CO2 mixing ratio to reduce measurement uncertainty. The measurements were calibrated against 2 NOAA (National Oceanic and Atmospheric Administration) primary standard tanks for CO2 mixing ratio and 1 JRAC (Jena Reference Air Cylinder) isotope primary standard for δ13C. A Keeling approach based on two-component mass and isotope balance was used to derive daily mean isotopic signatures of local CO2 from individual measurements of δ13CO2 and CO2 mixing ratios. The record covers a 2-year period, from July 2011 to July 2013. It shows a clear seasonal pattern, with less negative and less variable δ13CO2 values

  20. Analysis of High Frequency Site-Specific Nitrogen and Oxygen Isotopic Composition of Atmospheric Nitrous Oxide at Mace Head, Ireland

    Science.gov (United States)

    McClellan, M. J.; Harris, E. J.; Olszewski, W.; Ono, S.; Prinn, R. G.

    2014-12-01

    Atmospheric nitrous oxide (N2O) significantly impacts Earth's climate due to its dual role as an inert potent greenhouse gas in the troposphere and as a reactive source of ozone-destroying nitrogen oxides in the stratosphere. However, there remain significant uncertainties in the global budget of this gas. The marked spatial divide in its reactivity means that all stages in the N2O life cycle—emission, transport, and destruction—must be examined to understand the overall effect of N2O on climate. Source and sink processes of N2O lead to varying concentrations of N2O isotopologues (14N14N16O, 14N15N16O, 15N14N16O, and 14N14N18O being measured) due to preferential isotopic production and elimination in different environments. Estimation of source and sink fluxes can be improved by combining isotopically resolved N2O observations with simulations using a chemical transport model with reanalysis meteorology and treatments of isotopic signatures of specific surface sources and stratospheric intrusions. We present the first few months of site-specific nitrogen and oxygen isotopic composition data from the Stheno-TILDAS instrument (Harris et al, 2013) at Mace Head, Ireland and compare these to results from MOZART-4 (Model for Ozone and Related Chemical Tracers, version 4) chemical transport model runs including N2O isotopic fractionation processes and reanalysis meterological fields (NCEP/NCAR, MERRA, and GEOS-5). This study forms the basis for future inverse modeling experiments that will improve the accuracy of isotopically differentiated N2O emission and loss estimates. Ref: Harris, E., D. Nelson, W. Olszewski, M. Zahniser, K. Potter, B. McManus, A. Whitehill, R. Prinn, and S. Ono, Development of a spectroscopic technique for continuous online monitoring of oxygen and site-specific nitrogen isotopic composition of atmospheric nitrous oxide, Analytical Chemistry, 2013; DOI: 10.1021/ac403606u.

  1. Study of atmospheric pressure weakly ionized plasma as surface compatibilization technique for improved plastic composites loaded with cellulose based fillers

    Science.gov (United States)

    Lekobou, William Pimakouon

    Atmospheric pressure plasmas have gained considerable interest from researchers recently for their unique prospective of engineering surfaces with plasma without the need of vacuum systems. They offer the advantage of low energy consumption, minimal capital cost and their simplicity as compared to conventional low pressure plasmas make them easy to upscale from laboratory to industry size. The present dissertation summarizes results of our attempt at applying atmospheric pressure weakly ionized plasma (APWIP) to the engineering of plastic composites filled with cellulose based substrates. An APWIP reactor was designed and built based on a multipoint-to-grounded ring and screen configurations. The carrier gas was argon and acetylene serves as the precursor molecule. The APWIP reactors showed capability of depositing plasma polymerized coating rich in carbon on substrates positioned within the electrode gap as well as downstream of the plasma discharge into the afterglow region. Our findings show that films grow by forming islands which for prolonged deposition time grow into thin films showing nodules, aggregates of nodules and microspheres. They also show chemical structure similar to films deposited from hydrocarbons with other conventional plasma techniques. The plasma polymerized deposits were used on substrates to modify their surface properties. Results show the surface of wood veneer and wood flour can be finely tuned from hydrophilic to hydrophobic. It was achieved by altering the topography of the surfaces along with their chemical composition. The wettability of wood veneer was investigated with contact angle measurements on capacitive drops and the capillary effect was utilized to assess surface properties of wood flour exposed to the discharges.

  2. The influence of the Extreme Ultraviolet spectral energy distribution on the structure and composition of the upper atmosphere of exoplanets

    CERN Document Server

    Guo, J H

    2015-01-01

    By varying the profiles of stellar extreme ultraviolet (EUV) spectral energy distribution (SED), we tested the influences of stellar EUV SEDs on the physical and chemical properties of the escaping atmosphere. We apply our model to study four exoplanets, HD\\,189733b, HD\\,209458b, GJ \\,436b, and Kepler-11b. We found that the total mass loss rates of an exoplanet, which are determined mainly by the integrated fluxes, are moderately affected by the profiles of the EUV SED, but the composition and species distributions in the atmosphere can be dramatically modified by the different profiles of the EUV SED. For exoplanets with a high hydrodynamic escape parameter ($\\lambda$), the amount of atomic hydrogen produced by photoionization at different altitudes can vary by one to two orders of magnitude with the variation of stellar EUV SEDs. The effect of photoionization of H is prominent when the EUV SED is dominated by the low-energy spectral region (400-900${\\AA}$), which pushes the transition of H/H$^{+}$ to low al...

  3. Total and regional body-composition changes in early postmenopausal women

    DEFF Research Database (Denmark)

    Wang, Q; Hassager, C; Ravn, Pernil