Sample records for influence regional atmospheric

  1. Utility of soil linear alkylbenzenes to assess regional anthropogenic influences with special reference to atmospheric transport.

    PubMed

    Wei, Gao-Ling; Bao, Lian-Jun; Guo, Ling-Chuan; He, Zai-Cheng; Wu, Feng-Chang; Zeng, Eddy Y

    2014-07-15

    Tracing regional anthropogenic influences is important for assessing the magnitude of human interferences with the environment. In the present study, the utility of soil linear alkylbenzenes (LABs) as indicators of anthropogenic influences was examined, with the emphasis on the role of atmospheric transport in dissipating LABs from input sources to remote areas. The Pearl River Delta, South China, which has experienced rapid economic growth and urbanization, was selected as the study region. The concentrations of LABs (mean: 8.6 ng/g and median: 5.7 ng/g, with an outlier of 2,020 ng/g excluded) suggested that sewage contamination throughout the entire study region was generally light. The spatial variation of sewage pollution was significantly positively correlated with population density and per capita gross domestic product, with hot spots concentrated in the central PRD. Atmospheric deposition was hypothesized as an important input route for soil LABs in forestry and drinking water source areas with little impact of irrigation or direct wastewater discharge. This proposition could explain the opposite spatial patterns of LAB concentrations and values of a biodegradation index (5-C12+5-C13)/(5-C11+5-C10), where i-Cn defines a specific LAB congener with i and n indicating the position of the phenyl group and the number of carbon atoms on the alkyl chain, respectively. These findings somewhat validated LABs as tracers of regional anthropogenically derived contamination, with atmospheric transport of LABs as a viable dissipating mechanism. PMID:24813768

  2. Predicting Regional Transpiration at Elevated Atmospheric CO2: Influence of the PBL-Vegetation Interaction.

    NASA Astrophysics Data System (ADS)

    Jacobs, Cor M. J.; de Bruin, Henk A. R.

    1997-12-01

    A coupled planetary boundary layer (PBL)-vegetation model is used to study the influence of the PBL-vegetation interaction and the ambient CO2 concentration on surface resistance rs and regional transpiration E. Vegetation is described using the big-leaf model in which rs is modeled by means of a coupled photosynthesis-resistance model. The PBL part is a one-dimensional, first-order closure model. Nonlocal turbulent transport is accounted for by means of a countergradient correction. The PBL model also describes CO2 fluxes and concentrations, which are driven by photosynthesis of the canopy. A number of sensitivity analyses are presented in which the behavior of rs and E at an atmospheric CO2 concentration representative for the present-day situation is compared to their behavior under an approximately doubled CO2 concentration. The results reveal a positive atmospheric feedback on rs, by which an initial increase of rs, due to changes in ambient CO2 concentration, is magnified. The stomatal humidity response appears to be the key factor here: if rs increases, the air within the canopy dries out, which causes the stomata to close further. The PBL enlarges the effect of this positive feedback loop. The model suggests plants with a C4 photosynthetic pathway to be less sensitive to the humidity-mediated positive feedback than plants with a C3 photosynthetic pathway. Another important aspect of biosphere-atmosphere interaction is the negative feedback of the PBL on transpiration. It is concluded that the interaction between PBL and the vegetation has to be taken into account if transpiration and its changes, due to changing surface characteristics, are to be predicted at the regional scale. This conclusion applies to modeling studies as well as to extrapolation of results from plant physiological research or from small-scale field plots to the regional scale.

  3. Processes for identifying regional influences of and responses to increasing atmospheric CO sub 2 and climate change -- the MINK Project

    SciTech Connect

    Crosson, P.R.; Katz, L.A.; Wingard, J. (Resources for the Future, Inc., Washington, DC (United States))

    1991-08-01

    The second report of a series contributing to the study Processes for Identifying Regional Influences of and Responses to Increasing Atmospheric CO{sub 2} and Climate Change -- The MINK Project is composed of two parts. This Report (2A) treats agriculture in MINK in terms of state and region-wide production and resource use for the main crops and animals in the baseline periods of 1984/87 and 2030. The effects of the analog climate on the industry at this level of aggregation are considered in both baseline periods. 72 refs., 12 figs., 26 tabs.

  4. Processes for identifying regional influences of and responses to increasing atmospheric CO sub 2 and climate change: The MINK project

    SciTech Connect

    Darmstadter, J.

    1991-08-01

    This is the fifth of a series of reports of research contributing to the study Processes for Identifying Regional Influences of and Responses to Increasing Atmospheric CO{sub 2} and Climate Change -- The MINK Project. This report is directed to an analysis of the possible impacts of climatic change on energy in the Missouri-Iowa- Nebraska-Kansas (MINK) region. It follows a uniform methodological strategy that is applied to the four resource sectors most likely to be impacted by climate change, i.e. agriculture, forestry, water resources and energy. The methodological strategy is fully explained in Report 1 of this series. 43 refs., 1 fig. 12 tabs.

  5. Processes for identifying regional influences of and responses to increasing atmospheric CO sub 2 and climate change: The MINK project

    SciTech Connect

    Bowes, M.D.; Crosson, P.R.

    1991-08-01

    This is the sixth of a series of reports of research contributing to the study Processes for Identifying Regional Influences of and Responses to Increasing Atmospheric CO{sub 2} and Climate Change -- The MINK Project. This report is directed to providing an integrated analysis of the possible economic impacts of climatic change on resources in the Missouri-Iowa-Nebraska-Kansas (MINK) region. It is based on a uniform methodological strategy that was applied to the four resource sectors most likely to be impacted by climate change, i.e., agriculture, forestry, water resources and energy. The methodological strategy is fully explained in Report 1 of this series. 19 refs., 9 tabs.

  6. Processes for identifying regional influences of and responses to increasing atmospheric CO sub 2 and climate change: The MINK Project

    SciTech Connect

    Frederick, K.D.

    1991-08-01

    This is the fourth of a series of reports of research contributing to the study Processes for Identifying Regional Influences of and Responses to Increasing Atmospheric CO{sub 2} and Climate Change -- The MINK Project. This report is directed to an analysis of the possible impacts of climatic change on water resources in the Missouri -- Iowa -- Nebraska -- Kansas (MINK) region. It follows a uniform methodological strategy that is applied to the four resource sectors most likely to be impacted by climate change, i.e. agriculture, forestry, water resources and energy. The methodological strategy is fully explained in Report 1 of this series. 50 refs., 19 figs., 33 tabs.

  7. Processes for identifying regional influences of and responses to increasing atmospheric CO sub 2 and climate change --- the MINK Project

    SciTech Connect

    Not Available

    1991-08-01

    This is the first of a series of reports of research contributing to the study Processes for Identifying Regional Influences of and Responses to Increasing Atmospheric CO{sub 2} and Climate Change --MINK Project. This Report is intended to provide background information on project organization and methodology. In Sections 2 and 3 the region chosen for study and the scenario of climate change applied to it are described. The remainder of the paper provides information on the current functioning of the region -- its demography and macroeconomic characteristics, its major natural resource sectors, and way these sectors interlink among themselves and with other industries and the region's economic base. In the final section projections are made of the demographics and macroeconomic characteristics of the region 20 and 40 years into the future. 54 refs., 15 figs., 23 tabs.

  8. Processes for Identifying Regional Influences of and Responses to Increasing Atmospheric CO sub 2 and Climate Change --- The MINK Project

    SciTech Connect

    Easterling, W.E. III; McKenney, M.S.; Rosenberg, N.J.; Lemon, K.M.

    1991-08-01

    The second report of a series Processes for Identifying Regional Influences of and Responses to Increasing Atmospheric CO{sub 2} and Climate Change -- The MINK Project is composed of two parts. This Report (IIB) deals with agriculture at the level of farms and Major Land Resource Areas (MLRAs). The Erosion Productivity Impact Calculator (EPIC), a crop growth simulation model developed by scientists at the US Department of Agriculture, is used to study the impacts of the analog climate on yields of main crops in both the 1984/87 and the 2030 baselines. The results of this work with EPIC are the basis for the analysis of the climate change impacts on agriculture at the region-wide level undertaken in this report. Report IIA treats agriculture in MINK in terms of state and region-wide production and resource use for the main crops and animals in the baseline periods of 1984/87 and 2030. The effects of the analog climate on the industry at this level of aggregation are considered in both baseline periods. 41 refs., 40 figs., 46 tabs.

  9. Processes for identifying regional influences of and responses to increasing atmospheric CO sub 2 and climate change: The MINK project

    SciTech Connect

    Rosenberg, N.J.; Crosson, P.R.

    1991-08-01

    This overview report explains the rationale for and the methodology used in conduct of the study Processes for Identifying Regional Influences of and Responses to Increasing Atmospheric CO{sub 2} and Climate Change -- The MINK Project'' commissioned by the US Department of Energy. The MINK project includes four states -- Missouri, Iowa, Nebraska and Kansas. The major findings of the study are also presented in this overview, which accompanies a series of reports in which the requisite technical details on methodology, sectoral analyses and integrated analysis of climate change impacts and responses are provided in detail. The report topics in this analysis series of potential greenhouse effects are: (1) background and baseline; (2) agricultural production and resource use in the MINK region without and with climate change; (3) a farm-level simulation of the effects of climate change on crop productivity in the MINK region; (4) forest resources; (5) water resources; (6) energy; (7) consequences of climate change for the MINK economy: impacts and responses.

  10. The effect of regional-scale soil-moisture deficits on mesoscale atmospheric dynamics that influence fire severity

    SciTech Connect

    Fast, J.D.

    1994-09-30

    This study employs a three-dimensional, nonhydrostatic mesoscale model to evaluate the effects of horizontally heterogeneous soil moisture and vegetation type on the atmosphere during two periods in which wildland fires occurred. Numerical sensitivity simulations demonstrate that evapotranspiration significantly affects the boundary-layer structure embedded in the synoptic-scale circulations. In regions with sufficiently moist soils, evapotranspiration increases the humidity and modifies the diurnally varying temperature near the surface. Occasionally, changes in the humidity and temperature fields can also be seen a significant distance downwind of the moist soil regions. The perturbations in the temperature fields ultimately affect the wind speed and direction over or at the boundaries of the moist-soil regions, but only at certain times during the simulation period. The higher humidity also increases the cloudiness and changes the precipitation amounts, indicating that soil moisture and vegetation may play an important role in modifying the spatial distribution and intensity of precipitation. A lower atmospheric stability index, that is an indicator of the potential for wildland fire, is also calculated from the model results. This index is also sensitive to the horizontal distribution of soil moisture and vegetation, especially in regions with relatively moist soils. While only two periods are examined in this study, the impact of surface inhomogeneities in soil moisture and vegetation type on the atmosphere is expected to be highly dependent on the particular synoptic conditions and upon the distribution of soil moisture.

  11. The use of an atmospheric dispersion model to determine influence regions in the Prince George, B.C. airshed from the burning of open wood waste piles.

    PubMed

    Ainslie, B; Jackson, P L

    2009-06-01

    A means of determining air emission source regions adversely influencing the city of Prince George, British Columbia, Canada from potential burning of isolated piles of mountain pine beetle-killed lodge pole pine is presented. The analysis uses the CALPUFF atmospheric dispersion model to identify safe burning regions based on atmospheric stability and wind direction. Model results show that the location and extent of influence regions is sensitive to wind speed, wind direction, atmospheric stability and a threshold used to quantify excessive concentrations. A concentration threshold based on the Canada Wide PM(2.5) Standard is used to delineate the influence regions while Environment Canada's (EC) daily ventilation index (VI) is used to quantify local atmospheric stability. Results from the analysis, to be used by air quality meteorologists in assessing daily requests for burning permits, are presented as a series of maps delineating acceptable burning locations for sources placed at various distances from the city center and under different ventilation conditions. The results show that no burning should be allowed within 10 km of the city center; under poor ventilation conditions, no burning should be allowed within 20 km of the city center; under good ventilation conditions, burning can be allowed within 10-15 km of the city center; under good to fair ventilation conditions, burning can be allowed beyond 15 km of the city center; and if the wind direction can be reliably forecast, burning can be allowed between 5 and 10 km downwind of the city center under good ventilation conditions. PMID:19303193

  12. How the Atmosphere Influences Aridity

    NSDL National Science Digital Library

    This site, produced by the U.S. Geological Survey, describes the circulation pattern of Earth's atmosphere, which is influenced by differential heating and the Coriolis Effect. This circulation causes the formation of warm, dry areas on the Earth's surface which are where deserts are likely to exist. The site features text, a photograph, and a scientific illustration showing the atmospheric circulation pattern.

  13. Processes for identifying regional influences of and responses to increasing atmospheric CO sub 2 and climate change---The MINK Project

    SciTech Connect

    Bowes, M.D.; Sedjo, R.A.

    1991-08-01

    This is the third of a series of reports of research contributing to the study Processes for Identifying Regional Influences of an Responses to Increasing Atmospheric CO{sub 2} and Climate Change --The MINK Project. This report is an analysis of the possible impacts of climatic change on forest resources in the Missouri-Iowa-Nebraska-Kansas (MINK) region. It follows a uniform methodological strategy that is applied to the four resource sectors most likely to be impacted by climate change, i.e. agriculture, forestry, water resources and energy. What makes the forests of this region interesting is their great vulnerability to climate warming. With their position on the fringe of the eastern hardwood forest, bordering the grasslands of the midwest, it might be expected that these forests would be among the first to be affected by a changing climate. The state of the current forest resource are examined as well as, using simulation models, the likely sensitivity of the Missouri forests to a climate warming. The future development of forestry and forest technology in the region is considered. It is concluded that the low productivity of these forests rules out active adaptation to climate change, such as might expected in the region's agricultural sector or in the more productive forest regions of the US southeast or northwest. The forest sector is most likely to begin gradual and passive decline under a climate warming. 47 refs., 27 figs., 7 tabs.

  14. Regional Ecosystem-Atmosphere CO2 Exchange Via Atmospheric Budgets

    SciTech Connect

    Davis, K.J.; Richardson, S.J.; Miles, N.L.

    2007-03-07

    Inversions of atmospheric CO2 mixing ratio measurements to determine CO2 sources and sinks are typically limited to coarse spatial and temporal resolution. This limits our ability to evaluate efforts to upscale chamber- and stand-level CO2 flux measurements to regional scales, where coherent climate and ecosystem mechanisms govern the carbon cycle. As a step towards the goal of implementing atmospheric budget or inversion methodology on a regional scale, a network of five relatively inexpensive CO2 mixing ratio measurement systems was deployed on towers in northern Wisconsin. Four systems were distributed on a circle of roughly 150-km radius, surrounding one centrally located system at the WLEF tower near Park Falls, WI. All measurements were taken at a height of 76 m AGL. The systems used single-cell infrared CO2 analyzers (Licor, model LI-820) rather than the siginificantly more costly two-cell models, and were calibrated every two hours using four samples known to within ± 0.2 ppm CO2. Tests prior to deployment in which the systems sampled the same air indicate the precision of the systems to be better than ± 0.3 ppm and the accuracy, based on the difference between the daily mean of one system and a co-located NOAA-ESRL system, is consistently better than ± 0.3 ppm. We demonstrate the utility of the network in two ways. We interpret regional CO2 differences using a Lagrangian parcel approach. The difference in the CO2 mixing ratios across the network is at least 2?3 ppm, which is large compared to the accuracy and precision of the systems. Fluxes estimated assuming Lagrangian parcel transport are of the same sign and magnitude as eddy-covariance flux measurements at the centrally-located WLEF tower. These results indicate that the network will be useful in a full inversion model. Second, we present a case study involving a frontal passage through the region. The progression of a front across the network is evident; changes as large as four ppm in one minute are captured. Influence functions, derived using a Lagrangian Particle Dispersion model driven by the CSU Regional Atmospheric Modeling System and nudged to NCEP reanalysis meteorological fields, are used to determine source regions for the towers. The influence functions are combined with satellite vegetation observations to interpret the observed trends in CO2 concentration. Full inversions will combine these elements in a more formal analytic framework.

  15. Influence of aerosol source regions and transport pathway on ?D of terrestrial biomarkers in atmospheric aerosols from the East China Sea

    NASA Astrophysics Data System (ADS)

    Yamamoto, Shinya; Kawamura, Kimitaka; Seki, Osamu; Kariya, Tadashi; Lee, Meehye

    2013-04-01

    We measured stable hydrogen isotope ratios (?D) of terrestrial biomarkers (n-alkanes and n-fatty acids) in atmospheric total suspended particles collected at Jeju Island in the East China Sea, from April 2001 to March 2002, to better understand the influence of long-range atmospheric transport on their seasonal variations. The ?D values of the C27, C29 and C31n-alkanes (?DALK) show a significant negative correlation with the CPI values of n-alkanes (r2 = 0.26, p < 0.01), suggesting that the ?DALK variations are partly attributed to a superimposed contribution from fossil fuel hydrocarbons. Seasonal variations in the concentrations of the C22-C28 even-carbon numbered n-fatty acids revealed relatively high concentrations in spring, autumn and winter seasons, in which the air masses are transported from northeast Asia. In contrast, the concentrations are low in summer when the air masses are transported from Southeast Asia and the Pacific. Relatively high C26/FA and low C24/FA ratios in spring, autumn and winter samples suggest that the C26n-fatty acids are more abundantly transported from the Asian continent during these seasons. Seasonal variations in the ?D of the C22-C26 even-carbon numbered n-fatty acids exhibit significant enrichment with D (by ˜40‰) in May and June to August samples, whereas the ?D of the C28n-fatty acids gradually decrease during summer. The magnitude of the ?D offsets (˜45‰) between the C28n-fatty acid and the other homologues are much larger than those observed in East Asia spanning 18°N-50°N latitude (ca. 30‰), suggesting that the decoupling is likely attributed to the mixing of distinct source vegetation with different ?D ratios. Comparison of the weighted-mean ?D values of n-fatty acids (?DFA) between air mass source categories revealed relatively low values (˜-170‰) in samples with trajectories from the northeastern part of the Asian continent, supporting that the ?D analyses may be a powerful tool in deciphering the source regions of terrestrial biomarkers in atmospheric aerosols from the Asian continent. The results of this study provides important implications for paleoclimate studies that the ?D variations of long-range transported terrestrial biomarkers in remote ocean sediments may have recorded past changes in source strengths of the biomarkers and therefore have a potential to reconstruct paleo-wind patterns and transport of terrestrial carbon over the Pacific.

  16. Metal contamination and health risk from consumption of organically grown vegetables influenced by atmospheric deposition in a seasonally dry tropical region of India.

    PubMed

    Singh, Ashima; Pandey, Jitendra

    2012-08-01

    Pot-culture experiments showed that organically grown Vicia faba, influenced by atmospheric deposition, accumulated (?g g(-1)) 0.088-3.246 Cadmium, 0.19-42.48 Chromium, 0.0124-30.43 Copper, 0.075-4.28 Lead and 0.63-67.68 Zinc. Similar trends appeared for Abelmoschus esculentus. At high deposition sites, Cadmium, Lead and Zinc exceeded the safe limits of Prevention of Food Adulteration standards. Health risk index for Cadmium, Copper and Lead exceeded the safe limits of United States Environmental Protection Agency. The study suggests that atmospheric deposition could substantially elevate metal levels in organically grown vegetables in 2011. PMID:22653308

  17. Coarse-Resolution Daily Inundation Dynamics over the Alaska-Yukon Region: Comparison with High-Resolution Inundation Products and Influences from Atmospheric Drivers

    NASA Astrophysics Data System (ADS)

    Schroeder, R.; McDonald, K. C.; Rawlins, M. A.; Podest, E.; Whitcomb, J.; Mogahddam, M.; Zimmermann, R.

    2009-12-01

    Natural wetland complexes are a major source of atmospheric methane which is an important greenhouse gas. Wetland surface water variations and associated methane production are tightly linked and highly dependent on both climate and available plant material. Hence, characterizing the extent and distribution of wetlands is crucial in understanding the effect of climate change on wetlands dynamics, carbon and hydrological cycles, weather and biodiversity. This study presents a remote sensing technique for determining daily surface water fractions based on multiple satellite remote sensing data sets. The focus is on the Alaska-Yukon region and daily inundation dynamics for the period from 2002 until 2008. Our inundation detection approach employs passive microwave data from AMSR-E on NASA’s Earth Observing System (EOS) Aqua satellite and Leaf Area Index (LAI) from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the EOS Terra satellite. Radar backscatter from SeaWinds-on-QuikSCAT (QSCAT) is used to maximize the sensitivity to the presence of vegetation biomass in inundated areas. A comparison with high-resolution maps of open water and wetlands vegetation, derived from JERS SAR, and open water area, derived from LANDSAT, suggests that this mapping approach shows great potential for accurate mapping of inundation dynamics across this region. Variations in open water area as seen by LANDSAT and SAR imagery are detected, as well as the sensitivity to variations in inundated vegetation. We note reasonable agreement between surface inundation fraction, river discharge, and simulated river runoff simulated by a hydrological model, with pronounced interannual variations that could be explained by year-to-year changes in large-scale atmospheric circulation over Alaska. This work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration (NASA).

  18. Processes for identifying regional influences of and responses to increasing atmospheric CO{sub 2} and climate change - the MINK project: An overview

    SciTech Connect

    Rosenberg, N.J.; Crosson, P.R. [Resources for the Future, Washington, DC (United States)

    1991-08-01

    Scientists believe that a serious change in the climate of the earth could occur in the course of the next two to five decades as a result of warming caused by the rapid accumulation of radiatively active trace gases in the atmosphere. There is concern that not only the amount of warming but the rate at which it occurs could be unprecedented, at least since the current interglacial period began. Scientific uncertainties remain in our understanding of the climatic changes that may follow from greenhouse warming. Nevertheless, large and rapid changes in regional climate are conceivable. General circulation models (GCMs) predict changes for the central U.S. as large as an 8{degrees}C increase in mean summertime temperature accompanied by a 1 mm/day decrease in mean precipitation. Most predictions are less extreme but, so long as the direction of change is credible, efforts are warranted to identify just what kinds of impacts to expect if society chooses to allow climate to change or cannot stop it from changing, and just what might be done to adjust to those impacts.

  19. The regional atmospheric chemistry mechanism, version 2

    NASA Astrophysics Data System (ADS)

    Goliff, Wendy S.; Stockwell, William R.; Lawson, Charlene V.

    2013-04-01

    The Regional Atmospheric Chemistry Mechanism (RACM) is a gas-phase chemical mechanism that is widely used for the modeling of regional atmospheric chemistry. Much new data has been published since the original RACM was completed (Stockwell et al., 1997). The RACM mechanism was updated to create the Regional Atmospheric Chemistry Mechanism, version 2 (RACM2). Like the RACM1 mechanism, the RACM2 mechanism is designed to simulate remote to polluted conditions from the Earth's surface through the upper troposphere. The RACM2 mechanism includes updated reaction schemes, rate constants and product yields. It has been tested against environmental chamber data and compared with previous RACM scenario simulations. The aromatic chemistry was expanded to include a greater number of species with highly revised reaction schemes. The reaction mechanism for isoprene was expanded to include a more explicit treatment of methyl vinyl ketone. Alcohols were speciated to more accurately reflect peroxy-peroxy reactions in the remote atmosphere. Acetone was speciated due to its importance in the upper troposphere.

  20. Possible Solar Influence On Atmospheric Electric Field

    E-print Network

    Poonam Sikka; A. Mary Selvam; A. S. Ramachandra Murty; Bh. V. Ramana Murty

    1998-06-12

    A cell dynamical system model for the troposphere - ionosphere coupling is proposed . Vertical mass exchange in the troposphere-ionosphere-magnetosphere takes place through a chain of eddy systems. Any perturbation in the troposphere would be transmitted to ionosphere and vice versa. A global perturbation in ionosphere, as the one caused by solar variability, is transmitted to troposphere influencing weather systems/geomagnetic/atmospheric electrification processes.

  1. Influence of CO on Titan atmospheric reactivity

    NASA Astrophysics Data System (ADS)

    Fleury, B.; Carrasco, N.; Gautier, T.; Mahjoub, A.; He, J.; Szopa, C.; Buch, A.; Cernogora, G.

    2013-12-01

    The atmosphere of Titan is mainly composed of N2 and CH4, and photochemical volatiles products CxHyNz. Most of the laboratory studies simulating Titan's atmospheric reactivity focus on the highly complex carbon and nitrogen organic chemistry leading to a production of laboratory analogues of Titan's aerosols, called Tholins [Alcouffe et al., 2010]. However, the atmosphere of Titan also contains traces of oxygen compounds. The most abudant one detected is carbon monoxyde CO with a 47 ppmv concentration measured in high stratosphere [de Kok et al., 2007]. In this work we investigate the influence of CO on the N2-CH4 reactivity. We simulate the whole reaction chains with a laboratory Radio Frequency Capacitively Coupled plasma discharge (RF CCP) gas mixture of nitrogen, methane and carbon monoxyde. In order to detect unambiguously the possible effects, CO is introduced with amounts of 0 - 1 - 2.25 - 4.5 %, larger than in Titan's atmosphere. The kinetics of the methane is monitored by mass spectrometry and the compositions of the gas phase and tholins are monitored by GC-MS and elemental analysis respectively. We find that CO modifies the composition of the gas phase with the detection of oxygenated compounds. CO decreases drastically the production efficiency of tholins, involving also a perturbation on the methane kinetics. The oxygen incorporation in tholins is found to be efficient . As a conclusion, we show that carbon monoxyde is effectively coupled with N2-CH4 chemistry and that it impacts even the solid organic aerosols. References: Alcouffe, G., et al (2010), Capacitively coupled plasma used to simulate Titan's atmospheric chemistry, Plasma Sources Science and Technology, 19(1), 015008. de Kok, R., et al. (2007), Oxygen compounds in Titan's stratosphere as observed by Cassini CIRS, Icarus, 186(2), 354-363.

  2. Influence of CO on Titan atmospheric reactivity

    NASA Astrophysics Data System (ADS)

    Fleury, B.; Carrasco, N.; Gautier, T.; Mahjoub, A.; He, J.; Szopa, C.; Hadamcik, E.; Buch, A.; Cernogora, G.

    2014-08-01

    The atmosphere of Titan is mainly composed of N2 and CH4 which are the source of various CxHyNz photochemical volatiles products. Laboratory simulations of the Titan’s atmospheric reactivity were mainly interested in the study of the complex organic chemistry which leads to the formation of analogues of Titan’s aerosols, called tholins. These studies were mainly interested in the reactivity of the N2/CH4 gaseous mixture and with the primary products of reactions without oxygen. However, the atmosphere of Titan also contains oxygenated volatile species. The most abundant one to have been detected is CO with a concentration about 50 ppmv. The work presented here is an experimental simulation devoted to estimate the influence of CO on the Titan’s atmospheric reactivity. With this aim, CO is introduced in a standard N2/CH4 mixture at different mixing ratio up to 4.5%. The kinetics of the methane consumption is monitored with in situ mass spectrometry and the compositions of the gaseous phase and tholins produced in the reactor are characterized ex situ with GC-MS and elemental analysis. This work shows that CO modifies the composition of the gas phase with the detection of oxygenated compounds: CO2 and N2O. The presence of CO also drastically decreases the production rate of tholins, involving also a perturbation on the methane kinetics. Tholins are produced in lower global amounts, but their sizes are found to be significantly larger than without CO. The oxygen incorporation in tholins is found to be efficient, with an oxygen content of the same order of magnitude as the amount of CO in the initial gas mixture.

  3. Atmospheric influence on volcano-acoustic signals

    Microsoft Academic Search

    Robin Matoza; Catherine de Groot-Hedlin; Michael Hedlin; David Fee; Milton Garcés; Alexis Le Pichon

    2010-01-01

    Volcanoes are natural sources of infrasound, useful for studying infrasonic propagation in the atmosphere. Large, explosive volcanic eruptions typically produce signals that can be recorded at ranges of hundreds of kilometers propagating in atmospheric waveguides. In addition, sustained volcanic eruptions can produce smaller-amplitude repetitive signals recordable at >10 km range. These include repetitive impulsive signals and continuous tremor signals. The

  4. INFLUENCE OF AGRICULTURAL PRACTICES ON MICROMETEOROLOGICAL SPATIAL VARIATIONS AT THE LOCAL AND REGIONAL SCALES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil - vegetation - atmosphere transfers significantly influence interactions and feedbacks between vegetation and boundary layer, in relation with plant phenology and water status. The current study focused on linking micrometeorological conditions to cultural practices at the local and regional sc...

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

    NASA Astrophysics Data System (ADS)

    Uher, Erich J.

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

  6. ORIGINAL PAPER The influence of plants on atmospheric methane

    E-print Network

    Minnesota, University of

    ORIGINAL PAPER The influence of plants on atmospheric methane in an agriculture-dominated landscape waste sites (Le Mer and Roger 2001; Mosher et al. 1999; Shurpali et al. 1993; Shurpali and Verma 1998

  7. Atmospheric Turbulence and its Influence on Adaptive Optics

    E-print Network

    Tittley, Eric

    Atmospheric Turbulence and its Influence on Adaptive Optics Mike Campbell 23rd Summary 10 ii #12;1 Introduction Adaptive Optics (AO) is still a relatively young branch of astronomical of adaptive optics is to remove the distortions created by the atmosphere. To apply a change which flattens

  8. The influence of atmospheric stratification on scatterometer data

    NASA Technical Reports Server (NTRS)

    Louis, Jean-Francois; Hoffman, Ross N.

    1989-01-01

    The effects of atmospheric stratification and the stability of the atmospheric stratification on the scatterometer data measuring surface winds over the ocean were investigated using the boundary layer model developed by Louis (1979). A variational analysis method is proposed, which allows direct assimilation of scatterometer data. It is shown that the effect of the stability of atmospheric stratification on the wind increment is relatively small. However, it is a systematic effect, and neglecting it would consistently underestimate the winds in stable regions.

  9. Influence of the African Great Lakes on the regional climate

    NASA Astrophysics Data System (ADS)

    Thiery, Wim; Davin, Edouard; Panitz, Hans-Jürgen; Demuzere, Matthias; Lhermitte, Stef; van Lipzig, Nicole

    2015-04-01

    Although the African Great Lakes are important regulators for the East-African climate, their influence on atmospheric dynamics and the regional hydrological cycle remains poorly understood. We aim to assess this impact by conducting a regional climate model simulation which resolves individual lakes and explicitly computes lake temperatures. The regional climate model COSMO-CLM, coupled to a state-of-the-art lake parameterization scheme and land surface model, is used to dynamically downscale the COSMO-CLM CORDEX-Africa evaluation simulation to 7 km grid spacing for the period 1999-2008. Evaluation of the model reveals good performance compared to both in-situ and satellite observations, especially for spatio-temporal variability of lake surface temperatures and precipitation. Model integrations indicate that the four major African Great Lakes almost double precipitation amounts over their surface relative to a simulation without lakes, but hardly exert any influence on precipitation beyond their shores. The largest lakes also cool their near-surface air, this time with pronounced downwind influence. The lake-induced cooling happens during daytime, when the lakes absorb incoming solar radiation and inhibit upward turbulent heat transport. At night, when this heat is released, the lakes warm the near-surface air. Furthermore, Lake Victoria has profound influence on atmospheric dynamics and stability as it induces cellular motion with over-lake convective inhibition during daytime, and the reversed pattern at night. Overall, this study shows the added value of resolving individual lakes and realistically representing lake surface temperatures for climate studies in this region. Thiery, W., Davin, E., Panitz, H.-J., Demuzere, M., Lhermitte, S., van Lipzig, N.P.M., The impact of the African Great Lakes on the regional climate, J. Climate (in review).

  10. Atmospheric influence on volcano-acoustic signals

    NASA Astrophysics Data System (ADS)

    Matoza, Robin; de Groot-Hedlin, Catherine; Hedlin, Michael; Fee, David; Garcés, Milton; Le Pichon, Alexis

    2010-05-01

    Volcanoes are natural sources of infrasound, useful for studying infrasonic propagation in the atmosphere. Large, explosive volcanic eruptions typically produce signals that can be recorded at ranges of hundreds of kilometers propagating in atmospheric waveguides. In addition, sustained volcanic eruptions can produce smaller-amplitude repetitive signals recordable at >10 km range. These include repetitive impulsive signals and continuous tremor signals. The source functions of these signals can remain relatively invariant over timescales of weeks to months. Observed signal fluctuations from such persistent sources at an infrasound recording station may therefore be attributed to dynamic atmospheric propagation effects. We present examples of repetitive and sustained volcano infrasound sources at Mount St. Helens, Washington and Kilauea Volcano, Hawaii, USA. The data recorded at >10 km range show evidence of propagation effects induced by tropospheric variability at the mesoscale and microscale. Ray tracing and finite-difference simulations of the infrasound propagation produce qualitatively consistent results. However, the finite-difference simulations indicate that low-frequency effects such as diffraction, and scattering from topography may be important factors for infrasonic propagation at this scale.

  11. Generation of Regional Climate Ensembles Using Atmospheric Forcing Shifting

    NASA Astrophysics Data System (ADS)

    Sasse, R.; Schädler, G.; Feldmann, H.; Kottmeier, Ch.

    2012-04-01

    One of the main challenges in climate change research is improving knowledge about how regional climates may change in the next decades. Reliable information about changes of the mean climate state and extreme events such as heavy precipitation and dry spells are required for the water and risk management as well as for the development of adaptation and mitigation strategies. High-resolution ensembles are used to perform studies on the variability and change of regional climate and to assess the uncertainty of regional climate model (RCM) projections. In this study, we present Atmospheric Forcing Shifting (AFS) as an innovative ensemble generation technique and address the question how AFS affects the results of the regional climate simulations. Furthermore, the influence of synoptic conditions on the effect of AFS and the benefit of AFS for the generation of RCM ensembles are discussed. AFS is realised by introducing small shifts to the atmospheric fields derived from global data (here: ERA40 reanalyses) to each direction by 25 and 50 km, respectively. The shifted fields drive COSMO-CLM simulations for Europe with a horizontal resolution of 50 km. Besides the reference simulation, eight shifting scenarios are included into the RCM ensemble. The effect of AFS on 2m temperature and precipitation is studied for Central Europe and the period from 1980 to 1984. This includes the quantification and validation of the ensemble spread in comparison to the E-OBS dataset and COSMO-CLM simulations driven by different global climate models (GCMs). The investigation of the mean annual cycle and spatial distribution indicates that the effect of AFS on precipitation is larger and more heterogeneous than on 2m temperature. In summer, the ensemble variability is larger than in winter which is likely to be related to the frequency of synoptic conditions. Furthermore, AFS affects the probability distribution of 2m temperature and precipitation, including their extremes. Consequently, AFS may provide a suitable method to improve the statistics of extreme events. The next step is to generate an RCM ensemble with a resolution of 7 km for past (1971-2000) and future (2011-2040) decades using AFS and different GCMs. Based on the results, change signals of the mean climate state as well as of the likelihood and variability of extreme events will be determined.

  12. NAO influence on sea ice extent in the Eurasian coastal region Claes Rooth,2

    E-print Network

    Hu, Aixue

    NAO influence on sea ice extent in the Eurasian coastal region Aixue Hu,1 Claes Rooth,2 Rainer; published 20 November 2002. [1] Influence of winter pre-conditioning of Arctic sea ice due to atmospheric forcing associated with the North Atlantic Oscillation (NAO) on the reduction in summer sea ice extent

  13. Influence of regional scale information on the global circulation: A two-way nesting climate simulation

    Microsoft Academic Search

    Philip Lorenz; Daniela Jacob

    2005-01-01

    The influence of regional scale information on the global circulation has been investigated through the development and application of the so-called “two-way nesting” technique. The two-way nesting climate model system consists of a spectral atmospheric general circulation model and a grid point regional atmospheric model. Two simulations of 10 years each have been carried out with and without the feedback

  14. Influence of regional scale information on the global circulation: A two-way nesting climate simulation

    Microsoft Academic Search

    Philip Lorenz; Daniela Jacob

    2005-01-01

    The influence of regional scale information on the global circulation has been investigated through the development and application of the so-called ``two-way nesting'' technique. The two-way nesting climate model system consists of a spectral atmospheric general circulation model and a grid point regional atmospheric model. Two simulations of 10 years each have been carried out with and without the feedback

  15. Influence of the solar wind energy on the atmospheric processes

    Microsoft Academic Search

    M. Radovanovic; M. Stevancevic; D. Strbac

    2003-01-01

    After getting the first results from the satellite electromagnetic measures of parameters of the solar wind, it is noticed that under a certain conditions, the solar wind could have a very important influence on the atmospheric processes that is to say on the air masses moving. Satellite visual and infrared observations, as well as electromagnetic measures showed that the movements

  16. Influence of atmospheric circulation variations on the ozone layer

    Microsoft Academic Search

    E. A. Jadin; K. Y. A. Kondratyev; V. I. Bekoryukov; P. N. Vargin

    2005-01-01

    This paper reviews results related to the influence of long?term changes of the atmospheric wave activity and circulation on the ozone layer, in particular on the Antarctic ozone hole in 2002. These results provide evidence that an important role is played by natural factors in the ozone layer changes, together with the known anthropogenic impacts. Specifically, these factors are connected

  17. Identifying human influences on atmospheric temperature

    PubMed Central

    Santer, Benjamin D.; Painter, Jeffrey F.; Mears, Carl A.; Doutriaux, Charles; Caldwell, Peter; Arblaster, Julie M.; Cameron-Smith, Philip J.; Gillett, Nathan P.; Gleckler, Peter J.; Lanzante, John; Perlwitz, Judith; Solomon, Susan; Stott, Peter A.; Taylor, Karl E.; Terray, Laurent; Thorne, Peter W.; Wehner, Michael F.; Wentz, Frank J.; Wigley, Tom M. L.; Wilcox, Laura J.; Zou, Cheng-Zhi

    2013-01-01

    We perform a multimodel detection and attribution study with climate model simulation output and satellite-based measurements of tropospheric and stratospheric temperature change. We use simulation output from 20 climate models participating in phase 5 of the Coupled Model Intercomparison Project. This multimodel archive provides estimates of the signal pattern in response to combined anthropogenic and natural external forcing (the fingerprint) and the noise of internally generated variability. Using these estimates, we calculate signal-to-noise (S/N) ratios to quantify the strength of the fingerprint in the observations relative to fingerprint strength in natural climate noise. For changes in lower stratospheric temperature between 1979 and 2011, S/N ratios vary from 26 to 36, depending on the choice of observational dataset. In the lower troposphere, the fingerprint strength in observations is smaller, but S/N ratios are still significant at the 1% level or better, and range from three to eight. We find no evidence that these ratios are spuriously inflated by model variability errors. After removing all global mean signals, model fingerprints remain identifiable in 70% of the tests involving tropospheric temperature changes. Despite such agreement in the large-scale features of model and observed geographical patterns of atmospheric temperature change, most models do not replicate the size of the observed changes. On average, the models analyzed underestimate the observed cooling of the lower stratosphere and overestimate the warming of the troposphere. Although the precise causes of such differences are unclear, model biases in lower stratospheric temperature trends are likely to be reduced by more realistic treatment of stratospheric ozone depletion and volcanic aerosol forcing. PMID:23197824

  18. Regional modeling of surface-atmosphere interactions and their impact on Great Lakes hydroclimate

    NASA Astrophysics Data System (ADS)

    Steiner, A. L.; Bryan, A. M.; Posselt, D. J.

    2014-12-01

    Land and water surfaces play a critical role in hydroclimate by supplying moisture to the atmosphere, yet the ability of climate models to capture their feedbacks with the atmosphere relative to large-scale transport is uncertain. To assess these land-lake-atmosphere feedbacks, we compare the controls on atmospheric moisture simulated by a Regional Climate Model (RegCM) with observations and reanalysis products for the Great Lakes region. Three 23-year simulations with different boundary conditions are performed to capture the hydroclimatic variability with synoptic conditions. RegCM simulates wetter winters and drier summers than observed by up to 31 and 21%, respectively. Moisture advection exhibits similar biases, suggesting the contribution of external sources, yet land surface fluxes account for nearly one third of summer precipitation. RegCM underestimates reanalysis evapotranspiration by nearly 50%; however, the reanalyses overestimate measurements at three flux towers by up to a factor of two. Neither RegCM nor the reanalyses capture the spatial variability in observed land evaporation, indicating a source of model uncertainty. In addition, RegCM underestimates the observed evaporation response to its atmospheric drivers such as vapor pressure deficit and temperature. Over the lakes, one model member overestimates convective precipitation caused by enhanced evaporation under warm lake surface temperatures, highlighting the need for accurate representation of lake temperature in the surface boundary condition. We conclude that climate models, including those driving reanalyses, underestimate the observed surface-atmosphere feedbacks and their influence on regional hydroclimate.

  19. Surface roughness variations control the regional atmospheric response to contemporary scale deforestation in Rondônia, Brazil

    NASA Astrophysics Data System (ADS)

    Khanna, Jaya; Medvigy, David

    2015-04-01

    The atmospheric response to deforestation is closely tied to the scale of the land cover change. In the Amazon, deforestation at small scale (˜1 km) has been observed to give rise to an increase in cloudiness and rain, triggered by horizontal thermal variations between forest and bare land. Large scale (hundreds of kms) Amazonian deforestation, on the other hand, has been predicted to cause warming and drying. Noticeably, our knowledge of the net atmospheric response to intermediate scale (tens of kms) deforestation in the Amazon is incomplete and so the scale dependence of the regional atmospheric response is not well understood. This mesoresolution case study of contemporary deforestation in Rondônia, Brazil aims at investigating the coupled dynamical and thermodynamical regional atmospheric response to intermediate scale deforestation. Our numerical simulations, conducted using the variable resolution Ocean-Land-Atmosphere-Model, show that the regional atmospheric response to intermediate scales of deforestation is dominated by surface roughness variations between forests and clearings. These variations trigger a mesoscale circulation which makes the atmosphere conducive to convection in the downwind side and suppresses convection in the upwind side of the deforested domain. Unlike the thermally generated mesoscale circulations, which occur only during the dry season, this dynamically generated circulation is present year round. Moreover, the atmospheric response is found to be strongest during the wet season marked by an ˜8% increase (compared to the control case) in the relative humidity in and around the upwelling branch of the circulation. Overall the study shows that the atmospheric response to contemporary intermediate scale deforestation in Rondônia is likely to be more influenced by differences in surface roughness between forest and forest clearings than by the differences in the surface energy partitioning.

  20. Arctic atmospheric circulation patterns responsible for dry and cold air inflows to the Baltic Sea region

    NASA Astrophysics Data System (ADS)

    Post, Piia; Sepp, Mait

    2015-04-01

    Essential changes have taken place in atmospheric circulation over the Northern Atlantic in winter and spring during the second half of the 20th century. The winter temperature rise in Europe is frequently attributed to the intensification of zonal flow on the Northern Atlantic region and the same is valid for the Baltic Sea region. Intensification of zonal circulation and its expression through NAO and AO indices have been thoroughly studied, but less is known about mechanisms causing declination from the zonality of flow. Extremely cold weather in winter and spring in Baltic Sea region is related to the radiative cooling or advection of cold air masses. In both cases, the typical western flow is blocked and the region is directly influenced by atmospheric circulation conditions in the Arctic through the cold air advection events. Our aim is to study which large scale atmospheric circulation patterns are responsible for this kind of cold air advection to the Baltic Sea region in winter and spring (from December to May). The second task is to identify if this kind of circulation has become less frequent in the region under research beginning from the last half of the 20th century till now. Describing the atmospheric circulation patterns we use several classifications of atmospheric circulation on daily level. The domain of the classifications covers Atlantic-European sector of the Arctic, including area between Greenland and Novaya Zemlya archipelago. Manual classifications by Vangengeim-Girs and Dzerdzejevski are used, but also several newly calculated ones, that apply different classification methods from cost733class software. For the latter ones geopotential height fields at 500 hPa level from NCEP-NCAR reanalysis are classified for the period 1948-2013. The cold air advection events are determined by daily temperature drops by at least 3°C during 24 hours. The circulation types that bring advection of cold Arctic air to the Baltic Sea region are analysed in detail.

  1. Improving SLCF Science in the Himalayan Region: ICIMOD's Atmosphere Initiative

    NASA Astrophysics Data System (ADS)

    Panday, A. K.; Pradhan, B. B.; Surapipith, V.

    2013-12-01

    What fraction of the black carbon arriving on Yala Glacier in Langtang, Nepal, is from cooking fires in the houses in the valley below? What fraction is from elsewhere in rural Nepal? What fraction is from industrial and transport sources in Kathmandu? What fraction is from northern India and beyond? What fraction is from the high altitude forest fires that take place during March or April? Effectively mitigating the impacts of black carbon and other short-lived climate forcers requires detailed understanding not just of emissions and impacts, but also of the atmospheric transport pathways that connect the two. In mountainous areas of the Hindu-Kush Himalaya detailed quantitative knowledge about emissions, atmospheric processes, and impacts is still largely missing. The International Centre for Integrated Mountain Development (ICIMOD) is an intergovernmental organization covering Afghanistan, Pakistan, India, Nepal, China, Bhutan, Bangladesh, and Myanmar. ICIMOD's recently established Atmosphere Initiative not only assesses mitigation options and contributes to policy and capacity building in the region, but also works actively to promote collaboration among researchers in the region, while building up an in-house team whose research will address key questions about SLCF. In Spring 2013 ICIMOD's Atmosphere Initiative, in collaboration with the Institute for Advanced Sustainability Studies (IASS) in Potsdam, Germany, carried out the largest field campaign to date in Nepal, hosting instruments belonging to dozens of institutions around the world, at nine field site within and upwind of the Kathmandu Valley, Nepal. The dataset that has been collected gives unprecedented insights into the emissions and atmospheric processes taking place downwind of and within the largest urban agglomeration in the Himalaya region. Meanwhile, in collaboration with national partner institutions, ICIMOD is in the process of setting up one atmospheric observatory each in Bhutan and in Nepal. Each will be on a mountain peak overlooking the Indo-Gangetic Plains. A building will house laboratories and visitor space, and will have a small tower. Each site will be equipped with a Picarro G2401 analyzer for CO, CO¬2, methane and water vapor, aerosol filter samplers, as well as instruments to measure black carbon, ozone, aerosol size distribution, aerosol scattering, cloud condensation nuclei, solar radiation, aerosol optical depth, and meteorology. Together with output from ICIMOD's new atmospheric modeling centre, the data from the sites will allow quantifying the flux of pollutants from the Indo-Gangetic Plains towards the high Himalaya, and to estimate emissions of SLCFs within the Himalayan foothills region. The infrastructure at both observatory sites is designed to accommodate training and future expansion as well as to host visiting instruments.

  2. Relative Influence of Initial Surface and Atmospheric Conditions on Seasonal Water and Energy Balances

    NASA Technical Reports Server (NTRS)

    Oglesby, Robert J.; Marshall, Susan; Roads, John O.; Robertson, Franklin R.; Goodman, H. Michael (Technical Monitor)

    2001-01-01

    We constructed and analyzed wet and dry soil moisture composites for the mid-latitude GCIP region of the central US using long climate model simulations made with the NCAR CCM3 and reanalysis products from NCEP. Using the diagnostic composites as a guide, we have completed a series of predictability experiments in which we imposed soil water initial conditions in CCM3 for the GCIP region for June 1 from anomalously wet and dry years, with atmospheric initial conditions taken from June 1 of a year with 'near-normal' soil water, and initial soil water from the near-normal year and atmospheric initial conditions from the wet and dry years. Preliminary results indicate that the initial state of the atmosphere is more important than the initial state of soil water determining the subsequent late spring and summer evolution of sod water over the GCIP region. Surprisingly, neither the composites or the predictability experiments yielded a strong influence of soil moisture on the atmosphere. To explore this further, we have made runs with extreme dry soil moisture initial anomalies imposed over the GCIP region (the soil close to being completely dry). These runs did yield a very strong effect on the atmosphere that persisted for at least three months. We conclude that the magnitude of the initial soil moisture anomaly is crucial, at least in CCM3, and are currently investigating whether a threshold exists, below which little impact is seen. In a complementary study, we compared the impact of the initial condition of snow cover versus the initial atmospheric state over the western US (corresponding to the westward extension of the GAPP program follow-on to GCIP). In this case, the initial prescription of snow cover is far more important than the initial atmospheric state in determining the subsequent evolution of snow cover. We are currently working to understand the very different soil water and snow cover results.

  3. Regional differences in worldwide emissions of mercury to the atmosphere

    Microsoft Academic Search

    Nicola Pirrone; Gerald J. Keeler; Jerome O. Nriagu

    1996-01-01

    Annual emissions of anthropogenic Hg to the atmosphere in different regions of the world during the last decade show an interesting dichotomy: the emissions in the developed countries increased at the rate of about 4.5–5.5% yr?1 up to 1989 and have since remained nearly constant, while in developing countries the emissions continue to rise steadily at the rate of 2.7–4.5%

  4. Atmospheric attenuation studies in the 183-325 GHz region

    Microsoft Academic Search

    F. Ulaby; A. Straiton

    1969-01-01

    The absorption characteristics of the earth's atmosphere in the 183-325 GHz frequency region of the electromagnetic spectrum are investigated. Instrumentation problems associated with coherent radiometric detection dictated the use of a wide-band Germanium bolometer detector. Upon helium cooling the Germanium element to4.2degK the bolometer was observed to have a noise equivalent power of10^{-9}watts for a 1-Hz bandwidth. Using the sun

  5. Arctic Storms in a Regionally Refined Atmospheric General Circulation Model

    NASA Astrophysics Data System (ADS)

    Roesler, E. L.; Taylor, M.; Boslough, M.; Sullivan, S.

    2014-12-01

    Regional refinement in an atmospheric general circulation model is a new tool in atmospheric modeling. A regional high-resolution solution can be obtained without the computational cost of running a global high-resolution simulation as global climate models have increasing ability to resolve smaller spatial scales. Previous work has shown high-resolution simulations, i.e. 1/8 degree, and variable resolution utilities have resolved more fine-scale structure and mesoscale storms in the atmosphere than their low-resolution counterparts. We will describe an experiment designed to identify and study Arctic storms at two model resolutions. We used the Community Atmosphere Model, version 5, with the Spectral Element dynamical core at 1/8-degree and 1 degree horizontal resolutions to simulate the climatological year of 1850. Storms were detected using a low-pressure minima and vorticity maxima - finding algorithm. It was found the high-resolution 1/8-degree simulation had more storms in the Northern Hemisphere than the low-resolution 1-degree simulation. A variable resolution simulation with a global low resolution of 1-degree and a high-resolution refined region of 1/8 degree over a region in the Arctic is planned. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. SAND NO. 2014-16460A

  6. Automated Detection of Oscillating Regions in the Solar Atmosphere

    NASA Technical Reports Server (NTRS)

    Ireland, J.; Marsh, M. S.; Kucera, T. A.; Young, C. A.

    2010-01-01

    Recently observed oscillations in the solar atmosphere have been interpreted and modeled as magnetohydrodynamic wave modes. This has allowed for the estimation of parameters that are otherwise hard to derive, such as the coronal magnetic-field strength. This work crucially relies on the initial detection of the oscillations, which is commonly done manually. The volume of Solar Dynamics Observatory (SDO) data will make manual detection inefficient for detecting all of the oscillating regions. An algorithm is presented that automates the detection of areas of the solar atmosphere that support spatially extended oscillations. The algorithm identifies areas in the solar atmosphere whose oscillation content is described by a single, dominant oscillation within a user-defined frequency range. The method is based on Bayesian spectral analysis of time series and image filtering. A Bayesian approach sidesteps the need for an a-priori noise estimate to calculate rejection criteria for the observed signal, and it also provides estimates of oscillation frequency, amplitude, and noise, and the error in all of these quantities, in a self-consistent way. The algorithm also introduces the notion of quality measures to those regions for which a positive detection is claimed, allowing for simple post-detection discrimination by the user. The algorithm is demonstrated on two Transition Region and Coronal Explorer (TRACE) datasets, and comments regarding its suitability for oscillation detection in SDO are made.

  7. Critical review of studies on atmospheric dispersion in coastal regions

    SciTech Connect

    Shearer, D.L.; Kaleel, R.J.

    1982-09-01

    This study effort was required as a preliminary step prior to initiation of field measurements of atmospheric dispersion in coastal regions. The Nuclear Regulatory Commission (NRC) is in the process of planning an extensive field measurement program to generate data which will serve as improved data bases for licensing decisions, confirmation of regulations, standards, and guides, and for site characterizations. The study being reported here is an effort directed to obtaining as much information as is possible from existing studies that is relevant toward NRC's objectives. For this study, reports covering research and meteorological measurements conducted for industrial purposes, utility needs, military objectives, and academic studies were obtained and critically reviewed in light of NRC's current data needs. This report provides an interpretation of the extent of existing usable information, an indication of the potential for tailoring existing research toward current NRC information needs, and recommendations for several follow-on studies which could provide valuable additional information through reanalysis of the data. Recommendations are also offered regarding new measurement programs. Emphasis is placed on the identification and acquisition of data from atmospheric tracer studies conducted in coastal regions. A total of 225 references were identified which deal with the coastal atmosphere, including meteorological and tracer measurement programs, theoretical descriptions of the relevant processes, and dispersion models.

  8. Regional modeling of surface-atmosphere interactions and their impact on Great Lakes hydroclimate

    NASA Astrophysics Data System (ADS)

    Bryan, A. M.; Steiner, A. L.; Posselt, D. J.

    2015-02-01

    Land and water surfaces play a critical role in hydroclimate by supplying moisture to the atmosphere, yet the ability of climate models to capture their feedbacks with the atmosphere relative to large-scale transport is uncertain. To assess these land-lake-atmosphere feedbacks, we compare the controls on atmospheric moisture simulated by a regional climate model (RegCM) with observations and reanalysis products for the Great Lakes region. Three 23 year simulations, driven by one reanalysis product and two general circulation models, are performed. RegCM simulates wetter winters and drier summers than observed by up to 31 and 21%, respectively. Moisture advection exhibits similar biases, suggesting the contribution of external sources. Land surface fluxes account for nearly one third of summer precipitation according to two reanalysis products. RegCM underestimates reanalysis evapotranspiration by nearly 50%; however, the reanalyses overestimate measurements at three FLUXNET sites by up to a factor of 2, which may explain the model-reanalysis differences. Neither RegCM nor the reanalyses capture the spatial variability in land evapotranspiration observed across the three FLUXNET sites, indicating a source of model uncertainty. In addition, RegCM underestimates the observed evapotranspiration response to its atmospheric drivers such as vapor pressure deficit and temperature. Over the lakes, one model member overestimates convective precipitation caused by enhanced evaporation under warm lake surface temperatures, highlighting the need for accurate representation of lake temperature in the surface boundary condition. We conclude that climate models, including those driving reanalyses, underestimate the observed surface-atmosphere feedbacks and their influence on regional hydroclimate.

  9. Surface Roughness Variations control the Regional Atmospheric Response to Contemporary Deforestation in Rondônia, Brazil

    NASA Astrophysics Data System (ADS)

    Khanna, J.; Medvigy, D.

    2014-12-01

    The net atmospheric response to deforestation is known to be a combination of individual atmospheric processes and their interactions triggered by changes in various land surface characteristics. These individual responses also vary with the scale of deforestation. Previous studies of atmospheric impacts of Amazonian deforestation have focused on very small (~1 km) and very large (hundreds of km) scales of deforestation and have showed that different land surface properties can dominate the atmospheric response at different scales. However, analysis of the net atmospheric impact of intermediate-scale deforestation (tens of km) has received less attention, despite it being a better representative of the contemporary landscape in some parts of the Amazon. This study looks at the effects of contemporary intermediate-scale deforestation in Rondônia, Brazil, with an emphasis on the role of changes in surface roughness, using a variable-resolution GCM, the Ocean-Land-Atmosphere Model. It is found that reductions in surface roughness give rise to a mesoscale circulation that is capable of convective triggering but that weakens the turbulent energy fluxes between land and atmosphere. Overall, this mesoscale circulation causes distinct impacts on the hydroclimates of the western and eastern halves of Rondônia, increasing convection in the former while suppressing it in the latter. These results show that the regional atmospheric response to contemporary intermediate-scale deforestation in Rondônia is likely to be more influenced by differences in surface roughness between forest and forest clearings than by the differences in the surface energy partitioning which is the dominant factor at small scales of deforestation.

  10. The Regional Environmental Impacts of Atmospheric Aerosols over Egypt

    NASA Astrophysics Data System (ADS)

    Zakey, Ashraf; Ibrahim, Alaa

    2015-04-01

    Identifying the origin (natural versus anthropogenic) and the dynamics of aerosols over Egypt at varying temporal and spatial scales provide valuable knowledge on the regional climate impacts of aerosols and their ultimate connections to the Earth's regional climate system at the MENA region. At regional scale, Egypt is exposed to air pollution with levels exceeding typical air-quality standards. This is particularly true for the Nile Delta region, being at the crossroads of different aerosol species originating from local urban-industrial and biomass-burning activities, regional dust sources, and European pollution from the north. The Environmental Climate Model (EnvClimA) is used to investigate both of the biogenic and anthropogenic aerosols over Egypt. The dominant natural aerosols over Egypt are due to the sand and dust storms, which frequently occur during the transitional seasons (spring and autumn). In winter, the maximum frequency reaches 2 to 3 per day in the north, which decreases gradually southward with a frequency of 0.5-1 per day. Monitoring one of the most basic aerosol parameters, the aerosol optical depth (AOD), is a main experimental and modeling task in aerosol studies. We used the aerosol optical depth to quantify the amount and variability of aerosol loading in the atmospheric column over a certain areas. The aerosols optical depth from the model is higher in spring season due to the impacts of dust activity over Egypt as results of the westerly wind, which carries more dust particles from the Libyan Desert. The model result shows that the mass load of fine aerosols has a longer life-time than the coarse aerosols. In autumn season, the modelled aerosol optical depth tends to increase due to the biomass burning in the delta of Egypt. Natural aerosol from the model tends to scatter the solar radiation while most of the anthropogenic aerosols tend to absorb the longwave solar radiation. The overall results indicate that the AOD is lowest in winter due to airborne particles washed out by rain events. Conversely, the AOD increases in summer because particle accumulation is favored by the absence of precipitation during this season. Moreover, in summer, photochemical processes in the atmosphere lead to slight increases in the values of aerosol optical characteristics, despite lower wind speeds [hence less wind-blown dust] relative to other seasons. This study has been conducted under the PEER 2-239 research project titled "the Impact of Biogenic and Anthropogenic Atmospheric Aerosols to Climate in Egypt". Project website: CleanAirEgypt.org

  11. Simulation of fog influence on laser beam distribution in atmosphere

    NASA Astrophysics Data System (ADS)

    Vasinek, Vladimir; Latal, Jan; Koudelka, Petr; Vitasek, Jan; Witas, Karel; Hejduk, Stanislav

    2012-10-01

    Optical fibreless data networks P2P offer fast data transmissions with big transmittance from 1- 10 Gbps on a distance of 1- 6 km. Perfections of such networks are especially flexibility, rapid creation of communications. Sensitivity to atmospheric influences, necessity of light on sight belongs to disadvantages. Transmission through atmosphere be characterized by non-stationarity, inhomogeneity, the influences have random character. It means immediately that it is possible only with difficulty to project conclusions concerning to the measurement on one line upon fiberless line in another position. Contribution tackles a question of forming of the artificial hazy atmospheres, finding the statistical parameters of artificially created foggy atmospheres that could be reproduced to real environment. This work describes created laboratory apparatus powered with fog generator, heat source and ventilating fans, which allow in a controlled way to change the optical transmission inside the bounded space. Laser diode radiation at wavelength of 850 nm is transmitted into created space like this which is scanned with optical power meter after passing of artificially created turbulent vaporous environment. Changes in intensity of the passed lights are captured; the mean value and maximum deviation from the mean value are computed. In this way it is possible to change the reached specific attenuation in dB/km. Owing to turbulences it happens to deviations from the mean value, these abnormalities are characterized by the distribution function that describes the size of turbulences in time. By the help of ergodic theorem then it is possible to deduce that the distribution function of the foggy turbulences gained at continuous time evaluation has same history like the distribution function gained behind the same conditions in the setup in other times. It holds as well that these distribution functions are the same for variety of points in experimental space, provided there are well - kept the same conditions of turbulence creations. Contribution shows the experimental values, shapes of distribution functions, their influence on attenuation of fiberless communication lines and on achieved the transmission BER. At the present time the verification of conclusions is performed from the experimental model on outdoor connecting link working upon the distance of 1,3 km at the transmission rate of 1,25 Gbps.

  12. PUBLISHED ONLINE: 13 JANUARY 2013 | DOI: 10.1038/NGEO1687 Atmospheric iodine levels influenced by sea

    E-print Network

    Jacob, Daniel J.

    LETTERS PUBLISHED ONLINE: 13 JANUARY 2013 | DOI: 10.1038/NGEO1687 Atmospheric iodine levels influenced by sea surface emissions of inorganic iodine Lucy J. Carpenter1 *, Samantha M. MacDonald2 , Marvin. Plane2 * Naturally occurring bromine- and iodine-containing compounds substantially reduce regional

  13. Extensive regional atmospheric hydrocarbon pollution in the southwestern United States.

    PubMed

    Katzenstein, Aaron S; Doezema, Lambert A; Simpson, Isobel J; Blake, Donald R; Rowland, F Sherwood

    2003-10-14

    Light alkane hydrocarbons are present in major quantities in the near-surface atmosphere of Texas, Oklahoma, and Kansas during both autumn and spring seasons. In spring 2002, maximum mixing ratios of ethane [34 parts per 109 by volume (ppbv)], propane (20 ppbv), and n-butane (13 ppbv) were observed in north-central Texas. The elevated alkane mixing ratios are attributed to emissions from the oil and natural gas industry. Measured alkyl nitrate mixing ratios were comparable to urban smog values, indicating active photochemistry in the presence of nitrogen oxides, and therefore with abundant formation of tropospheric ozone. We estimate that 4-6 teragrams of methane are released annually within the region and represents a significant fraction of the estimated total U.S. emissions. This result suggests that total U.S. natural gas emissions may have been underestimated. Annual ethane emissions from the study region are estimated to be 0.3-0.5 teragrams. PMID:14530403

  14. Extensive regional atmospheric hydrocarbon pollution in the southwestern United States

    PubMed Central

    Katzenstein, Aaron S.; Doezema, Lambert A.; Simpson, Isobel J.; Blake, Donald R.; Rowland, F. Sherwood

    2003-01-01

    Light alkane hydrocarbons are present in major quantities in the near-surface atmosphere of Texas, Oklahoma, and Kansas during both autumn and spring seasons. In spring 2002, maximum mixing ratios of ethane [34 parts per 109 by volume (ppbv)], propane (20 ppbv), and n-butane (13 ppbv) were observed in north-central Texas. The elevated alkane mixing ratios are attributed to emissions from the oil and natural gas industry. Measured alkyl nitrate mixing ratios were comparable to urban smog values, indicating active photochemistry in the presence of nitrogen oxides, and therefore with abundant formation of tropospheric ozone. We estimate that 4–6 teragrams of methane are released annually within the region and represents a significant fraction of the estimated total U.S. emissions. This result suggests that total U.S. natural gas emissions may have been underestimated. Annual ethane emissions from the study region are estimated to be 0.3–0.5 teragrams. PMID:14530403

  15. Middle Atmosphere Program. Handbook for MAP. Volume 16: Atmospheric Structure and Its Variation in the Region 20 to 120 Km. Draft of a New Reference Middle Atmosphere

    NASA Technical Reports Server (NTRS)

    Labitzke, K. (editor); Barnett, J. J. (editor); Edwards, B. (editor)

    1985-01-01

    A draft of a new reference atmosphere for the region between 20 and 80 km which depends largely on recent satellite experiments covering the globe from 80 deg S to 80 deg N is given. A separate international tropical reference atmosphere is given, as well as reference ozone models for the middle atmosphere.

  16. Influence of local and regional sources on the observed spatial and temporal variability of size resolved atmospheric aerosol mass concentrations and water-soluble species in the Athens metropolitan area

    NASA Astrophysics Data System (ADS)

    Eleftheriadis, Konstantinos; Ochsenkuhn, Klaus M.; Lymperopoulou, Theopisti; Karanasiou, Angeliki; Razos, Panayiotis; Ochsenkuhn-Petropoulou, Maria

    2014-11-01

    The variability of common aerosol species in large Metropolitan urban areas is a major air quality issue with strong health impacts of large populations. PM10 and PM2.5 particulate matter samples were obtained at three sites characteristic of industrial, urban traffic and sub-urban residential areas in the Athens basin. Samples were analysed for anions (Cl-, NO3-, SO42-) and cations (K+, Na+, Ca2+, Mg2+, NH4+) using ion chromatography. The spatial and temporal variability for the particulate matter (PM) concentration mass and water-soluble ionic species concentrations for the investigated sites were studied. Mean PM fine concentration levels were 20% higher at the industrial and the central urban areas compared to those in the suburban area (24.2 ?g/m3). The mean values for the coarse fraction at those two sites were two to three times higher compared to those at the suburban site (12.4 ?g/m3). Comparable concentration levels of most species were observed in all areas, while SO42- and NO3- differ at a significant level. Furthermore, the average size distributions of the mass and individual ions at the suburban site (NCSR Demokritos) showed a bimodal size distribution. SO42- and NH4+ have their main peak in the fine fraction while NO3- showed equal distribution on the fine and coarse mode.. Good correlation was found for SO42- and NO3- with Ca2+ and Na+ with Cl- for the coarse fraction in the industrial area. NH4+ was closely correlated with SO42- in the fine particles and in all areas. For the urban site the best correlations in coarse particulates were reported between Na+/Mg2+-Cl-, Ca2+/Mg2+-SO42-, explained by neutralization of acidic aerosol by soil dust and sea salt in the coarse fraction. Moreover, time weighted concentrations roses at the industrial and urban sites, showed no significant directional dependence, indicating either uniform generation of mainly the coarse species within the metropolitan area or major influence of the regional background for the fine aerosol species.

  17. Influence of Atmospheric Pressure and Composition on LIBS

    SciTech Connect

    Jeremy J. Hatch [Pacific Univ., Forest Grove, OR (United States). Dept. of Chemistry; Jill R. Scott [Idaho National Laboratory (INL), Idaho Falls, ID (United States). Chemical and Radiation Measurement; Effenberger, A. J. Jr. [Univ. of California, San Diego, CA (United States). Center for Energy Research

    2014-03-01

    Most LIBS experiments are conducted at standard atmospheric pressure in air. However, there are LIBS studies that vary the pressure and composition of the gas. These studies have provided insights into fundamentals of the mechanisms that lead to the emission and methods for improving the quality of LIBS spectra. These atmospheric studies are difficult because the effects of pressure and gas composition and interconnected, making interpretation of the results difficult. The influence of pressures below and above 760 Torr have been explored. Performing LIBS on a surface at reduced pressures (<760 Torr) can result in enhanced spectra due to higher resolution, increased intensity, improved signal-to-noise (S/N), and increased ablation. Lower pressures produce increased resolution because the line width in LIBS spectra is predominantly due to Stark and Doppler broadening. Stark broadening is primarily caused from collisions between electrons and atoms, while Doppler broadening is proportional to the plasma temperature. Close examination using a high resolution spectrometer reveals that spectra show significant peak broadening and self-absorption as pressures increase, especially for pressures >760 Torr. During LIBS plasma expansion, energy is lost to the surrounding atmosphere, which reduces the lifetime of the laser plasma. Therefore, reducing the pressure increases the lifetime of the plasma, allowing more light from the laser plasma to be collected; thus, increasing the observed signal intensity. However, if pressures are too low (<10 Torr), then there is a steep drop in LIBS spectral intensity. This loss in intensity is mostly due to a disordered plasma that results from the lack of sufficient atmosphere to provide adequate confinement. At reduced pressures, the plasma expands into a less dense atmosphere, which results in a less dense shock wave. The reduced density in the shock wave results in reduced plasma shielding, allowing more photons to reach the sample. Increasing the number of photons interacting with the sample surface results in increased ablation, which can lead to increased intensity. The composition of the background gas has been shown to greatly influence the observed LIBS spectra by altering the plasma temperature, electron density, mass removal, and plasma shielding that impact the emission intensity and peak resolution. It has been reported that atmospheric Ar results in the highest plasma temperature and electron density, while a He atmosphere results in the lowest plasma temperatures and electron density. Studying temporal data, it was also found that Ar had the slowest decay of both electron density and plasma temperature, while He had the fastest decay in both parameters. The higher plasma temperature and electron density results in an increase in line broadenin, or poor resolution, for Ar compared to He. A rapidly developing LIBS plasma with a sufficient amount of electrons can absorb a significant portion of the laser pulse through inverse Bremsstahlung. Ar (15.8 eV ) is more easily ionized than He (24.4 eV). The breakdown threshold for He at 760 Torr is approximately 3 times greater than Ar and approximately 5 times greater at 100 Torr. The lower breakdown threshold in Ar, compared to He, creates an environment favorable for plasma shielding, which reduces sample vaporization and leads to a weaker LIBS signal.

  18. The Anthropogenic Influence on Atmospheric Carbonyl Sulfide: Implications for Inverse Analysis of Process-Level Carbon Cycle Fluxes

    NASA Astrophysics Data System (ADS)

    Zumkehr, A. L.; Hilton, T. W.; Whelan, M.; Smith, S. J.; Campbell, J. E.

    2014-12-01

    Carbonyl sulfide (COS) is the most abundant sulfur containing gas in the troposphere and a significant precursor to stratospheric aerosol. Recent insights on the plant uptake of atmospheric COS suggest that plant uptake is the largest component of the global COS budget and that COS may provide a powerful new tool for partitioning sources and sinks of atmospheric CO2 at regional to global scales. However, alternative sources and sinks of COS must also be accounted for to minimize the uncertainty of this carbon cycle tracer approach. Here we focus on direct and indirect sources of atmospheric COS from anthropogenic activities. We construct bottom-up gridded inventories of anthropogenic COS sources and compare these to previous estimates that were based on relatively sparse emissions data. Furthermore, we simulate COS concentrations with an regional atmospheric chemistry model to show the influence of these alternative source estimates in relation to plant uptake at a range of surface and airborne monitoring sites.

  19. Atmospheric Impact of Large Methane Emission in the Arctic Region

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, S.; Cameron-Smith, P. J.; Bergmann, D.; Reagan, M. T.; Collins, W.; Elliott, S. M.; Maltrud, M. E.

    2011-12-01

    A highly potent greenhouse gas, methane, is locked in the solid phase as ice-like deposits containing a mixture of water and gas (mostly methane) called clathrates, in ocean sediments and underneath permafrost regions. Clathrates are stable under high pressure and low temperatures. Recent estimates suggest that about 1600 - 2000GtC of clathrates are present in oceans and 400GtC in Arctic permafrost (Archer et al.2009) which is about 4000 times that of current annual emissions. In a warming climate, increase in ocean temperatures could alter the geothermal gradient, which in turn could lead to dissociation of the clathrates and release of methane into the ocean and subsequently into the atmosphere as well. This could be of particular importance in the shallow part of the Arctic Ocean where the clathrates are found in depths of only 300m. In this presentation, we shall show results from our ongoing simulation of a scenario of large scale methane outgassing from clathrate dissociation due to warming ocean temperatures in the Arctic based on ocean sediment modeling. To that end we use the CESM (Community Earth System Model) version 1 with fully active coupled atmosphere-ocean-land model together with fast atmospheric chemistry module to simulate the response to increasing methane emissions in the Barents Sea, Canadian Archipelago and the Sea of Okhotsk. The simulation shows the effect these methane emissions could have on global surface methane, surface ozone, surface air temperature and other related indices. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-491764

  20. Influence of wind direction on pollen concentration in the atmosphere

    NASA Astrophysics Data System (ADS)

    Silva Palacios, I.; Tormo Molina, R.; Muñoz Rodríguez, A. F.

    The daily pollen concentration in the atmosphere of Badajoz (SW Spain) was analysed over a 6-year period (1993-1998) using a volumetric aerobiological trap. The results for the main pollination period are compared with the number of hours of wind each day in the four quadrants: 1 (NE), 2 (SE), 3 (SW) and 4 (NW). The pollen source distribution allowed 16 pollen types to be analysed as a function of their distribution in the four quadrants with respect to the location of the trap. Four of them correspond to species growing in an irrigated farmland environment (Amaranthaceae-Chenopodiaceae, Plantago, Scirpus, and Typha), five to riparian and woodland species (Salix, Fraxinus, Alnus, Populus, and Eucalyptus), four to urban ornamentals (Ulmus, Arecaceae, Cupressaceae, and Casuarina), and three which include the most frequent pollen grains of widely distributed species (Poaceae, Quercus, and Olea). The results show that the distribution of the sources and the wind direction play a very major role in determining the pollen concentration in the atmosphere when these sources are located in certain quadrants, and that the widely distributed pollen sources show no relationship with wind direction. In some years the values of the correlations were not maintained, which leads one to presume that, in order to draw significant conclusions and establish clear patterns of the influence of wind direction, a continuous and more prolonged study will be required.

  1. The Long-term Middle Atmospheric Influence of Very Large Solar Proton Events

    NASA Technical Reports Server (NTRS)

    Jackman, Charles H.; Marsh, Daniel R.; Vitt, Francis M.; Garcia, Rolando R.; Randall, Cora E.; Fleming, Eric L.; Frith, Stacey M.

    2008-01-01

    Long-term variations in ozone have been caused by both natural and humankind related processes. The humankind or anthropogenic influence on ozone originates from the chlorofluorocarbons and halons (chlorine and bromine) and has led to international regulations greatly limiting the release of these substances. Certain natural ozone influences are also important in polar regions and are caused by the impact of solar charged particles on the atmosphere. Such natural variations have been studied in order to better quantify the human influence on polar ozone. Large-scale explosions on the Sun near solar maximum lead to emissions of charged particles (mainly protons and electrons), some of which enter the Earth's magnetosphere and rain down on the polar regions. "Solar proton events" have been used to describe these phenomena since the protons associated with these solar events sometimes create a significant atmospheric disturbance. We have used the National Center for Atmospheric Research (NCAR) Whole Atmosphere Community Climate Model (WACCM) to study the long-term (> few months) influences of solar proton events from 1963 through 2004 on stratospheric ozone and temperature. There were extremely large solar proton events in 1972, 1989,2000,2001, and 2003. These events caused very distinctive polar changes in layers of the Earth's atmosphere known as the stratosphere (12-50 km; -7-30 miles) and mesosphere (50-90 km; 30-55 miles). The solar protons connected with these events created hydrogen- and nitrogen-containing compounds, which led to the polar ozone destruction. The nitrogen-containing compounds, called odd nitrogen, lasted much longer than the hydrogen-containing compounds and led to long-lived stratospheric impacts. An extremely active period for these events occurred in the five-year period, 2000- 2004, and caused increases in odd nitrogen which lasted for several months after individual events. Associated stratospheric ozone decreases of >lo% were calculated to last for up to five months past the largest events. However, the computed total column ozone and stratospheric temperature changes connected with the solar events were not found to be statistically significant. Thus, solar proton events do not likely contribute significantly to measured total column ozone fluctuations and stratospheric temperature changes.

  2. Soil occupation and atmospheric variations over Sobradinho Lake area. Part two: a regional modeling study

    NASA Astrophysics Data System (ADS)

    Correia, M. F.; da Silva Dias, M. A. F.; da Silva Aragão, M. R.

    2006-11-01

    The impact of the changes on soil cover and land use brought about by the construction of the Sobradinho Dam in the semi-arid region of the São Francisco River Hydrographic Basin is analyzed by means of a numerical model RAMS. Disregarding the influence of a large scale flow, a set of factors were responsible for the creation of a rather complex circulation system that includes mountain-valley winds, lake breeze (LB) and non-conventional circulation all induced by the surface non-homogeneous aspect. Results have demonstrated that the implementation of works of such magnitude brings about environmental changes in an area that stretches far beyond the surroundings of the reservoir. The soil cover alterations due to the ever increasing development of the area with the presence of irrigated crops in a sparsely vegetated region ( caatinga) does affect land surface characteristics, occasioning for that matter the splitting of the available energy into latent and sensible heat fluxes. LB behavior varies in accordance with atmospheric conditions and also in view of the type of vegetation found in the lake surrounding areas. Hydro availability in root zones, even under adverse atmospheric conditions (high temperature and low air humidity) brings up the high rates of evaporation and plant transpiration that contribute towards the increase of humidity and the fall of temperature in lower atmospheric layers.

  3. Regional High-resolution Coupled Atmosphere Ocean Modelling in the North Sea Region

    NASA Astrophysics Data System (ADS)

    Dumenil-Gates, Lydia; Bülow, Katharina; Ganske, Anette; Heinrich, Hartmut; Klein, Birgit; Klein, Holger; Möller, Jens; Rosenhagen, Gudrun; Schade, Nils; Hüttl-Kabus, Sabine; Tinz, Birger

    2015-04-01

    The analysis of climate projections in the North Sea area is one of the research tasks of the research programme KLIWAS of the German Federal Ministry of Transport and Digital Infrastructure. A multi-model ensemble of three coupled regional atmosphere-ocean models was set up comprising very high resolution simulations for the German coastal regions of the North Sea and the Baltic to represent the complex land-sea-atmosphere conditions in the region. The ensemble consists of simulations made in cooperation with the Swedish Meteorological and Hydrological Institute, the Climate Service Centre and the Max-Planck-Institute for the period of 1950 to 2100. The KLIWAS project thereby adds coupled models to the band-width of possible future climate conditions in the atmosphere as given by the ENSEMBLES project, which were also analyzed. The coupled results are evaluated for present-day climate using a North Sea climatology of maritime conditions at a matching high resolution. In the future climate, while air and water temperatures will rise to the year 2100, the mean wind speed does not show a significant trend, but large decadal variability. The frequency of occurrence of westerly wind directions increases in the majority of simulations and results in an increase of significant wave height in the eastern parts of the North Sea. In an interdisciplinary approach, these results are used to provide regional to local information for the development of adaptation strategies for the estuary, and climate-proofing of infrastructure in the wider context of the project.

  4. Rare earth element components in atmospheric particulates in the Bayan Obo mine region.

    PubMed

    Wang, Lingqing; Liang, Tao; Zhang, Qian; Li, Kexin

    2014-05-01

    The Bayan Obo mine, located in Inner Mongolia, China, is the largest light rare earth body ever found in the world. The research for rare earth elements (REEs) enrichment in atmospheric particulates caused by mining and ore processing is fairly limited so far. In this paper, atmospheric particulates including total suspended particulate (TSP) matter and particles with an equivalent aerodynamic diameter less than 10 ?m (PM10) were collected around the Bayan Obo mine region, in August 2012 and March 2013, to analyze the levels and distributions of REEs in particles. The total concentrations of REEs for TSP were 149.8 and 239.6 ng/m(3), and those for PM10 were 42.8 and 68.9 ng/m(3), in August 2012 and March 2013, respectively. Enrichment factor was calculated for all 14 REEs in the TSP and PM10 and the results indicated that REEs enrichment in atmosphere particulates was caused by anthropogenic sources and influenced by the strong wind in springtime. The spatial distribution of REEs in TSP showed a strong gradient concentration in the prevailing wind direction. REE chondrite normalized patterns of TSP and PM10 were similar and the normalized curves inclined to the right side, showing the conspicuous fractionation between the light REEs and heavy REE, which supported by the chondrite normalized concentration ratios calculated for selected elements (La(N)/Yb(N), La(N)/Sm(N), Gd(N)/Yb(N)). PMID:24657942

  5. Influence of atmospheric circulation on turbulent air-sea heat fluxes over the Mediterranean Sea during winter

    NASA Astrophysics Data System (ADS)

    Papadopoulos, Vassilis P.; Kontoyiannis, Harilaos; Ruiz, Simón; Zarokanellos, Nikolaos

    2012-03-01

    The influence of the winter atmospheric circulation on the turbulent variables of the air-sea boundary layer in the Mediterranean Sea is investigated. We examine the effects of several climatic indices and the corresponding large scale atmospheric patterns on the above variables by using a correlation analysis. The spatial characteristics and the behavior of the turbulent variables are also examined based on standard deviation and EOF analysis. Two main types of response to the index-specified atmospheric patterns have been identified: (1) A relatively uniform response of the entire basin associated with the influence of the East Atlantic pattern and (2) opposite responses in the western and eastern sub-basins linked mainly to the intrabasin SLP. The latter is a combined effect of the first four modes of atmospheric variability in the North Atlantic/Eurasia region, the North Atlantic Oscillation (NAO), the East Atlantic Pattern (EA), the Scandinavian Pattern (SCAND), and the East Atlantic-West Russia Pattern (EAWR). The two identified responses of the Mediterranean Sea to the atmospheric forcing are also in accordance with the primary modes of variability of the turbulent variables that result in the EOF analysis. All of the statistically independent indices (NAO, EA, SCAND, EAWR) have to be considered in order to fully account for the modulation of the turbulent variables in the Mediterranean Sea. As an example we refer to the mechanism through which, independent modes of atmospheric variability contributed to the Eastern Mediterranean Transient event between 1987 and 1995.

  6. East African food security as influenced by future climate change and land use change at local to regional scales

    Microsoft Academic Search

    Nathan Moore; Gopal Alagarswamy; Bryan Pijanowski; Philip Thornton; Brent Lofgren; Jennifer Olson; Jeffrey Andresen; Pius Yanda; Jiaguo Qi

    2012-01-01

    Climate change impacts food production systems, particularly in locations with large, vulnerable populations. Elevated greenhouse\\u000a gases (GHG), as well as land cover\\/land use change (LCLUC), can influence regional climate dynamics. Biophysical factors such\\u000a as topography, soil type, and seasonal rainfall can strongly affect crop yields. We used a regional climate model derived\\u000a from the Regional Atmospheric Modeling System (RAMS) to

  7. Isolating mesoscale coupled ocean-atmosphere interactions in the Kuroshio Extension region

    NASA Astrophysics Data System (ADS)

    Putrasahan, Dian A.; Miller, Arthur J.; Seo, Hyodae

    2013-09-01

    The Kuroshio Extension region is characterized by energetic oceanic mesoscale and frontal variability that alters the air-sea fluxes that can influence large-scale climate variability in the North Pacific. We investigate this mesoscale air-sea coupling using a regional eddy-resolving coupled ocean-atmosphere (OA) model that downscales the observed large-scale climate variability from 2001 to 2007. The model simulates many aspects of the observed seasonal cycle of OA coupling strength for both momentum and turbulent heat fluxes. We introduce a new modeling approach to study the scale-dependence of two well-known mechanisms for the surface wind response to mesoscale sea surface temperatures (SSTs), namely, the 'vertical mixing mechanism' (VMM) and the 'pressure adjustment mechanism' (PAM). We compare the fully coupled model to the same model with an online, 2-D spatial smoother applied to remove the mesoscale SST field felt by the atmosphere. Both VMM and PAM are found to be active during the strong wintertime peak seen in the coupling strength in both the model and observations. For VMM, large-scale SST gradients surprisingly generate coupling between downwind SST gradient and wind stress divergence that is often stronger than the coupling on the mesoscale, indicating their joint importance in OA interaction in this region. In contrast, VMM coupling between crosswind SST gradient and wind stress curl occurs only on the mesoscale, and not over large-scale SST gradients, indicating the essential role of the ocean mesocale. For PAM, the model results indicate that coupling between the Laplacian of sea level pressure and surface wind convergence occurs for both mesoscale and large-scale processes, but inclusion of the mesoscale roughly doubles the coupling strength. Coupling between latent heat flux and SST is found to be significant throughout the entire seasonal cycle in both fully coupled mode and large-scale coupled mode, with peak coupling during winter months. The atmospheric response to the oceanic mesoscale SST is also studied by comparing the fully coupled run to an uncoupled atmospheric model forced with smoothed SST prescribed from the coupled run. Precipitation anomalies are found to be forced by surface wind convergence patterns that are driven by mesoscale SST gradients, indicating the importance of the ocean forcing the atmosphere at this scale.

  8. Atmospheric Variability And Its Influence On Winter Hydroclimate In Upstate New York

    NASA Astrophysics Data System (ADS)

    Millar, S. W.

    2008-12-01

    Hydroclimatic trends are frequently used to assess regional impacts of global climate change, requiring that the combined effects of linear trends and non-linear quasi-periodic fluctuations associated with hemispheric- scale teleconnections be identified. Separating these effects is especially problematic outside the statistical nodes of influence, such as in the Great Lakes drainage area of Upstate New York (UNY). Daily mean temperature, precipitation and snowfall data, and streamflow were analyzed from 1950 to 2007, to determine relationships between regional hydroclimate and atmospheric teleconnections. Non-parameteric testing was used: the Mann-Kendall trend test to assess linear changes; and the Kruskal-Wallis and multiple comparison tests to observe differences due to the NAO, ENSO, PNA, and PDO teleconnections. The results highlight five key findings: the importance of the NAO on regional temperatures in December; the significance of the PNA and PDO on January hydroclimate; the role of ENSO in March snowfall; a strong linear trend in October of increasing precipitation, decreasing temperature and increasing streamflow; and a strong linear increase in snowfall in the lake snow-affected regions. Teleconnection linkages generally parallel relationships observed in neighboring regions; however, effects in UNY follow an intra-seasonal variation in Atlantic and Pacific influences. For winter forecasting these results suggest an affinity with New England in December, Ohio River Valley in January, and the Great Lakes in March. Aside from the NAO, the lack of regional coherence suggests, that although subhemispheric-scale linkages exist, they are not the dominant signal; the increasing January snowfall is a long-term linear change.

  9. Two centuries of observed atmospheric variability and change over the North Sea region

    NASA Astrophysics Data System (ADS)

    Stendel, Martin; van den Besselaar, Else; Hannachi, Abdel; Kent, Elizabeth; Lefebvre, Christiana; van Oldenborgh, Geert Jan; Rosenhagen, Gudrun; Schenk, Frederik; van der Schrier, Gerard

    2015-04-01

    Situated in northwestern Europe, the North Sea region is under influence of air masses from subtropical to arctic origin, and thus exhibits significant natural climate variability. As the land areas surrounding the North Sea are densely populated, climate change is an important issue in terms of e.g. coastal protection, fishery and trade. This study is part of the NOSCCA initiative (North Sea Region Climate Change Assessment) and presents observed variability and changes in atmospheric parameters during the last roughly 200 years. Circulation patterns show considerable decadal variability. In recent decades, a northward shift of storm tracks and increased cyclonic activity has been observed. There is also an indication of increased persistence of weather types. The wind climate is dominated by large multidecadal variability, and no robust long-term trends can be identified in the available datasets. There is a clear positive trend in near-surface temperatures, in particular during spring and winter. Over the region as a whole, no clear long-term precipitation trends are visible, although regional indications exist for an increased risk of extreme precipitation events.

  10. Rare earth element components in atmospheric particulates in the Bayan Obo mine region

    SciTech Connect

    Wang, Lingqing, E-mail: wanglq@igsnrr.ac.cn; Liang, Tao, E-mail: liangt@igsnrr.ac.cn; Zhang, Qian; Li, Kexin

    2014-05-01

    The Bayan Obo mine, located in Inner Mongolia, China, is the largest light rare earth body ever found in the world. The research for rare earth elements (REEs) enrichment in atmospheric particulates caused by mining and ore processing is fairly limited so far. In this paper, atmospheric particulates including total suspended particulate (TSP) matter and particles with an equivalent aerodynamic diameter less than 10 ?m (PM{sub 10}) were collected around the Bayan Obo mine region, in August 2012 and March 2013, to analyze the levels and distributions of REEs in particles. The total concentrations of REEs for TSP were 149.8 and 239.6 ng/m{sup 3}, and those for PM{sub 10} were 42.8 and 68.9 ng/m{sup 3}, in August 2012 and March 2013, respectively. Enrichment factor was calculated for all 14 REEs in the TSP and PM{sub 10} and the results indicated that REEs enrichment in atmosphere particulates was caused by anthropogenic sources and influenced by the strong wind in springtime. The spatial distribution of REEs in TSP showed a strong gradient concentration in the prevailing wind direction. REE chondrite normalized patterns of TSP and PM{sub 10} were similar and the normalized curves inclined to the right side, showing the conspicuous fractionation between the light REEs and heavy REE, which supported by the chondrite normalized concentration ratios calculated for selected elements (La{sub N}/Yb{sub N}, La{sub N}/Sm{sub N}, Gd{sub N}/Yb{sub N}). - Highlights: • TSP and PM{sub 10} samples were collected to analyze the levels and distributions of REE. • Enrichment factors indicated that REE enrichment was caused by anthropogenic sources. • The distribution of REEs showed a strong gradient in the prevailing wind direction. • Obvious fractionation between LREEs and HREEs is observed in atmospheric particulates.

  11. Can we distinguish fluxes from transport in regional-scale atmospheric inversions?

    NASA Astrophysics Data System (ADS)

    Davis, K. J.; Normile, C. P.; Diaz Isaac, L. I.; Lauvaux, T.; Berry, J. A.; Browell, E. V.; Denning, S.

    2013-12-01

    Atmospheric inversions to determine land-atmosphere exchange of CO2 or other trace gases rely heavily upon accurate representation of atmospheric transport. Limited knowledge of land-atmosphere fluxes and atmospheric transport make it difficult to use existing atmospheric observations to determine land-atmosphere fluxes with accuracy. Restated, it is very difficult to determine whether model-data differences in atmospheric CO2 are due to flaws in modeled transport or fluxes. For regional models, limited information about CO2 lateral boundary conditions further complicate this situation. Flux, boundary conditions and transport errors, however, may have characteristic signatures in atmospheric properties, including CO2 mole fractions, associated trace gases and atmospheric state variables that enable these errors to be distinguished unambiguously. This paper presents a preliminary comparative investigation of the nature of flux vs. transport vs. boundary errors, focusing on the continental scale. We attempt to identify observational approaches that could capitalize on these characteristic differences to provide independent constraints of flux, boundary and transport errors, thus potentially improving substantially the accuracy of atmospheric inverse estimates of land-atmosphere fluxes. Potential observations that will be considered include column CO2 from satellites, trace gases such as CO, atmospheric properties including winds and potential temperature, aircraft profile and ground-based column CO2 measurements, and spatially extensive airborne observations. Our results will be translated into recommendations for future atmospheric observational efforts.

  12. Influence of Atmospheric CO2 Variation on Strom Track Behavior

    NASA Astrophysics Data System (ADS)

    Martynova, Yuliya; Krupchatnikov, Vladimir

    2015-04-01

    The storm tracks are the regions of strong baroclinicity where surface cyclones occur. The effect of increase with following decrease of anthropogenic load on storm tracks activity in the Northern Hemisphere was studied. The global climate system model of intermediate complexity ('Planet Simulator', Fraedrich K. et al., 2005) was used in this study. Anthropogenic forcing was set according to climatic scenario RCP8.5 continued till 4000 AD with fixed CO2 concentration till 3000 AD and linear decrease of anthropogenic load to preindustrial value at two different rates: for 100 and 1000 years. Modeling data analysis showed meridional shift of storm tracks due to atmospheric CO2 concentration variation. When CO2 concentration increases storm tracks demonstrate poleward shifting. When CO2 concentration decreases to preindustrial value storm tracks demonstrate a tendency to equator-ward shifting. Storm tracks, however, don't recover their original activity and location to the full. This manifests itself particularly for 'fast' CO2 concentration decrease. Heat and moisture fluxes demonstrate the same behavior. In addition, analysis of eddy length scale (Kidston J. Et al., 2011) showed their increase at mid-latitudes and decrease at tropic latitudes due to intensive CO2 concentration increase. This might cause poleward shift of mid-latitude jets. Acknowledgements. This work is partially supported by SB RAS project VIII.80.2.1, RFBR grant 13-05-12034, 13-05-00480, 14-05-00502 and grant of the President of the Russian Federation. Fraedrich K., Jansen H., Kirk E., Luksch U., and Lunkeit F. The Planet Simulator: Towards a user friendly model // Meteorol. Zeitschrift. 2005, 14, 299-304. Kidston J., Vallis G.K., Dean S.M., Renwick J.A. Can the increase in the eddy length scale ander global warming cause the poleward shift of the jet streams? // J. Climate. 2011, V.24. P. 3764-3780.

  13. Atmospheric profiles of CO? as integrators of regional scale exchange 

    E-print Network

    Smallman, Thomas Luke

    2014-06-30

    The global climate is changing due to the accumulation of greenhouse gases (GHGs) in the atmosphere, primarily due to anthropogenic activity. The dominant GHG is CO? which originates from combustion of fossil fuels, land use change and management...

  14. Atmospheric Rivers Induced Heavy Precipitation and Flooding in the Western U.S. Simulated by the WRF Regional Climate Model

    SciTech Connect

    Leung, Lai R.; Qian, Yun

    2009-02-12

    Twenty years of regional climate simulated by the Weather Research and Forecasting model for North America has been analyzed to study the influence of the atmospheric rivers and the role of the land surface on heavy precipitation and flooding in the western U.S. Compared to observations, the simulation realistically captured the 95th percentile extreme precipitation, mean precipitation intensity, as well as the mean precipitation and temperature anomalies of all the atmospheric river events between 1980-1999. Contrasting the 1986 President Day and 1997 New Year Day atmospheric river events, differences in atmospheric stability are found to have an influence on the spatial distribution of precipitation in the Coastal Range of northern California. Although both cases yield similar amounts of heavy precipitation, the 1997 case was found to produce more runoff compared to the 1986 case. Antecedent soil moisture, the ratio of snowfall to total precipitation (which depends on temperature), and existing snowpack all seem to play a role, leading to a higher runoff to precipitation ratio simulated for the 1997 case. This study underscores the importance of characterizing or simulating atmospheric rivers and the land surface conditions for predicting floods, and for assessing the potential impacts of climate change on heavy precipitation and flooding in the western U.S.

  15. Theoretical investigation of the influence of a quasi-2-day wave on nonlinear photochemical oscillations in the mesopause region

    Microsoft Academic Search

    M. Y. Kulikov

    2007-01-01

    The influence of a quasi-2-day atmospheric wave of given amplitude on the 2-day photochemical oscillations occurring in the mesopause region (heights of 80 to 90 km) in the regime of subharmonic nonlinear response to diurnal variations of solar radiation is investigated. It is revealed that the most significant mechanism is periodic transport of minor gas constituents by the vertical wind

  16. Effect of East Asia summer blocking on the atmospheric circulation over the region

    NASA Astrophysics Data System (ADS)

    Ahn, Joong-Bae; Park, Yong-Jun

    2015-04-01

    The influence of the boreal summer blocking on atmospheric circulation in East Asia was examined. The summer blocking occurred mostly in North Europe, Ural region, Sea of Okhotsk (OK), and northeastern Pacific. The summer blocking was the major mode in these four regions according to principal component analysis using 500 hPa geopotential heights. Among the four blocking regions, OK blocking frequencies (OK BFs) showed negative and positive correlations with summer temperature and precipitation of Northeast Asia centered around the East Sea/Sea of Japan, respectively. In particular, the OK BF had a statistically significant correlation coefficient of -0.54 with summer temperatures in the Korean Peninsula. This indicates that the summer temperature and precipitation in this region were closely related to the OK blocking. According to the composite analysis for the years of higher-than-average BF (positive BF years), the OK High became stronger and expanded, while the North Pacific High was weakened over the Korean Peninsula and Japan and an anomalously deep trough was developed in the upper layer (200 hPa). As the cool OK High expanded, the temperature decreased over Northeast Asia centered around the East Sea/Sea of Japan and the lower level (850 hPa) air converged cyclonically, resulting in the increased precipitation, which induced the divergence in the upper layer and thereby strengthened the jet stream. Thus, the boreal summer OK blocking systematically influencing the area as the most dominant mode. Acknowledgements This work was carried out with the support of Rural Development Administration Cooperative Research Program for Agriculture Science and Technology Development under grant project PJ009353 and Korea Meteorological Administration Research and Development Program under grant CATER 2012-3100, Republic of Korea.

  17. Regional atmospheric circulation shifts induced by a grand solar minimum

    NASA Astrophysics Data System (ADS)

    Martin-Puertas, Celia; Matthes, Katja; Brauer, Achim; Muscheler, Raimund; Hansen, Felicitas; Petrick, Christof; Aldahan, Ala; Possnert, Göran; van Geel, Bas

    2012-06-01

    Large changes in solar ultraviolet radiation can indirectly affect climate by inducing atmospheric changes. Specifically, it has been suggested that centennial-scale climate variability during the Holocene epoch was controlled by the Sun. However, the amplitude of solar forcing is small when compared with the climatic effects and, without reliable data sets, it is unclear which feedback mechanisms could have amplified the forcing. Here we analyse annually laminated sediments of Lake Meerfelder Maar, Germany, to derive variations in wind strength and the rate of 10Be accumulation, a proxy for solar activity, from 3,300 to 2,000 years before present. We find a sharp increase in windiness and cosmogenic 10Be deposition 2,759 +/- 39 varve years before present and a reduction in both entities 199 +/- 9 annual layers later. We infer that the atmospheric circulation reacted abruptly and in phase with the solar minimum. A shift in atmospheric circulation in response to changes in solar activity is broadly consistent with atmospheric circulation patterns in long-term climate model simulations, and in reanalysis data that assimilate observations from recent solar minima into a climate model. We conclude that changes in atmospheric circulation amplified the solar signal and caused abrupt climate change about 2,800 years ago, coincident with a grand solar minimum.

  18. Influence of atmospheric pollution on nutrient limitation in the ocean

    Microsoft Academic Search

    Kent A. Fanning

    1989-01-01

    IN the midst of the debate over the ocean being phosphorus- or nitrogen-limited1,2, the 'acid rain' controversy prompted studies related to the atmospheric transport and delivery of pollutant nitrogen compounds over the ocean3-9. Some of those investigations concluded that atmospheric nitrogen had only minimal effects on euphotic-zone productivity7,8 or on nitrate at the Atlantic thermocline9, thus suggesting a negligible oceanic

  19. Influence of Atmospheric Nuclear Explosions on Climate Change

    Microsoft Academic Search

    Yoshiaki Fujii

    This article suggests that the 0.5K stagnation in the global-mean surface temperature (GST) between 1945 and 1976 would be due to the atmospheric nuclear explosions, namely, Gadget, Little Boy, Fat Man and the succeeding at least 422 times nuclear weapons testing between 1946 and 1980. Estimation on GST drop due to the atmospheric nuclear explosions based on the published numerical

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

    EPA Science Inventory

    We incorporate the recently developed Regional Atmospheric Chemistry Mechanism (version 2, RACM2) into the Community Multiscale Air Quality modeling system for comparison with the existing 2005 Carbon Bond mechanism with updated toluene chemistry (CB05TU). Compared to CB05TU, RAC...

  1. Precipitation, sublimation, and snow drift in the Antarctic Peninsula region from a regional atmospheric model

    NASA Astrophysics Data System (ADS)

    van Lipzig, N. P. M.; King, J. C.; Lachlan-Cope, T. A.; van den Broeke, M. R.

    2004-12-01

    A regional atmospheric model, with a horizontal grid spacing (?x) of 14 km, is used to study the surface mass balance components (precipitation, sublimation, and snow drift) in the region of the Antarctic Peninsula (AP). An integration is performed for the 7-year period 1987-1993, using a realistic forcing at the lateral model boundaries and at the sea surface. Output from this integration indicates that the precipitation reaches its maximum value on the northwestern slope of the AP, where the upward motion in the atmosphere is largest. Uplift occurs upstream of the barrier, affecting the precipitation distribution over sea. The effect of the barrier on the precipitation distribution over the Bellingshausen Sea might have important implications for the ocean circulation in this region. The mean precipitation over the grounded ice of the AP (1.20 m water eq yr-1) is 6 times larger than the mean value over all the grounded ice of Antarctica. Our estimates for the surface sublimation and wind transport of snow over the grounding line toward the sea are 9% and 6 ± 1% of the precipitation, respectively. In situ data of the wind distribution at three coastal sites located on the northern, eastern, and western sides of the AP are used to evaluate the modeled wind field, which is important for the snow drift calculations. For two of the three sites considered, the prevailing wind direction and bimodal wind distribution are correctly represented by the model. The calculated distribution of accumulation and ablation due to snow drift shows a complex pattern. The wind removes snow from the spine of the AP, where the near-surface flow field diverges, whereas deposition occurs mainly on the eastern slopes, where the near-surface flow field converges. An intercomparison between two 7-year integrations at different horizontal resolution (?x = 14 km and ?x = 55 km) shows that the precipitation on the northwestern slope is very sensitive to the model resolution: In the ?x = 14 km integration, precipitation on the northwestern slope is higher than in ?x = 55 km because of higher vertical velocities, resulting in a 35% increase in average precipitation over the grounded ice of the AP.

  2. REGIONAL MODELING OF THE ATMOSPHERIC TRANSPORT AND DEPOSITION OF ATRAZINE

    EPA Science Inventory

    A version of the Community Multiscale Air Quality (CMAQ) model has been developed by the U.S. EPA that is capable of addressing the atmospheric fate, transport and deposition of some common trace toxics. An initial, 36-km rectangular grid-cell application for atrazine has been...

  3. Atmospheric winter conditions 2007/08 over the Arctic Ocean based on NP-35 data and regional model simulations

    NASA Astrophysics Data System (ADS)

    Mielke, M.; Zinoviev, N. S.; Dethloff, K.; Rinke, A.; Kustov, V. J.; Makshtas, A. P.; Sokolov, V. T.; Neuber, R.; Maturilli, M.; Klaus, D.; Handorf, D.; Graeser, J.

    2014-05-01

    Atmospheric measurements on the drifting Arctic sea ice station "North Pole-35" crossing the Eastern part of the Arctic Ocean during winter 2007/2008 have been compared with regional atmospheric HIRHAM model simulations. The observed near-surface temperature, mean sea level pressure and the vertical temperature, wind and humidity profiles are satisfactorily reproduced by the model. The strongest temperature differences between observations and the simulations occur near the surface due to an overestimated vertical mixing of heat in the stable Arctic boundary layer (ABL). The observations show very strong temperature inversions near the surface, whereas the simulated inversions occur frequently between the surface and 415 m at too high levels. The simulations are not able to reproduce the observed inversion strength. The regional model underestimates the wind speeds and the sharp vertical wind gradients. The strength of internal atmospheric dynamics on the temporal development of atmospheric surface variables and vertical profiles of temperature, wind and relative humidity has been examined. Although the HIRHAM model systematically overestimates relative humidity and produces too high long-wave downward radiation during winter, two different atmospheric circulation states, which are connected to higher or lower pressure systems over the Eastern part of the Arctic Ocean, are simulated in agreement with the NP-35 observations. Sensitivity studies with reduced vertical mixing of heat in the stable ABL have been carried out. A slower increase in the stability functions with decreasing Richardson number under stable stratification has an impact on the horizontal and vertical atmospheric structure. Changes in synoptical cyclones on time scales from 1-3 days over the North Atlantic cyclone path are generated, which influences the atmospheric baroclinic and planetary waves on time scales up to 20 days over the Arctic Ocean basin. The use of increased vertical stability in the model simulation leads to diminished planetary-scale variability over the Arctic Ocean.

  4. Contrasting Regional Responses to Increasing Leaf-Level Atmospheric Carbon Dioxide over Australia

    E-print Network

    Evans, Jason

    Contrasting Regional Responses to Increasing Leaf-Level Atmospheric Carbon Dioxide over Australia, New South Wales, Australia JOHN L. MCGREGOR Centre for Australian Weather and Climate Research, and CSIRO Marine and Atmospheric Research, Aspendale, Victoria, Australia JASON P. EVANS Climate Change

  5. Regional hydrologic consequences of increases in atmospheric CO2 and other trace gases

    Microsoft Academic Search

    Peter H. Gleick

    1987-01-01

    Concern over changes in global climate caused by growing atmospheric concentrations of carbon dioxide and other trace gases has increased in recent years as our understanding of atmospheric dynamics and global climate systems has improved. Yet despite a growing understanding of climatic processes, many of the effects of human-induced climatic changes are still poorly understood. Major alterations in regional hydrologic

  6. Influence of a sample surface on single electrode atmospheric plasma jet parameters

    NASA Astrophysics Data System (ADS)

    Zaplotnik, Rok; Biš?an, Marijan; Kregar, Zlatko; Cvelbar, Uroš; Mozeti?, Miran; Miloševi?, Slobodan

    2015-01-01

    The article reports on reciprocal influence between the sample surface and atmospheric plasma jet. This correlation is important since it changes plasma parameters and plasma itself, depending on the sample-material surface, presence of liquid or treatment distance. However, in experiments and treatments of surfaces with atmospheric plasma jets, this relationship is usually disregarded. In order to investigate reciprocal influence, we implemented electromagnetic and optical emission spectroscopy characterization of atmospheric plasma needle jet. Characterization was performed during treatment of various samples. We have shown that sample material and its distance from the tip of the electrode have a pronounced influence on atmospheric pressure plasma jet electromagnetic and optical characteristics, such as jet length, shape, color, voltage, current, power, electromagnetic field and concentrations of plasma species. It was shown that for a given flow there is a critical distance (? 15 mm) between the tip of the wire and the sample surface for which jet emission intensity, especially ionic, is at maximum.

  7. Solar activity influences on atmospheric electricity and on some structures in the middle atmosphere

    NASA Technical Reports Server (NTRS)

    Reiter, Reinhold

    1989-01-01

    Only processes in the troposphere and the lower stratosphere are reviewed. General aspects of global atmospheric electricity are summarized in Chapter 3 of NCR (1986); Volland (1984) has outlined the overall problems of atmospheric electrodynamics; and Roble and Hays (1982) published a summary of solar effects on the global circuit. The solar variability and its atmospheric effects (overview by Donelly et al, 1987) and the solar-planetary relationships (survey by James et al. 1983) are so extremely complex that only particular results and selected papers of direct relevance or historical importance are compiled herein.

  8. TELEMEDICINE TO ASSIST PATIENT UNDERSTANDING OF ATMOSPHERIC INFLUENCE ON LUNG FUNCTION AND IMPROVE

    E-print Network

    McSharry, Patrick E.

    TELEMEDICINE TO ASSIST PATIENT UNDERSTANDING OF ATMOSPHERIC INFLUENCE ON LUNG FUNCTION AND IMPROVE-time generic telemedicine system is presented. It is discussed in the context of self- management for people as influencing lung function, we have used data collected during a feasibility study of the telemedicine system

  9. Influence of Mesoscale Ocean Wind Variability on Tropical Atmospheric Convection

    NASA Astrophysics Data System (ADS)

    Choi, S.; Nesbitt, S. W.; Lang, T. J.; Chronis, T.

    2014-12-01

    The atmosphere and ocean are tightly coupled elements of the climate system, yet many of their interactions remain poorly understood. In particular, our knowledge of the relationship between precipitation and synoptic/mesoscale sea surface wind patterns suffers due to the lack of observations over the ocean. Satellite-based scatterometer wind retrievals, with their ability to observe surface winds near rainfall, coupled with atmospheric reanalysis enable the investigation of the relationships between flows and surface atmosphere exchanges of water and energy near precipitation. In this study, we examine the interactions between surface wind features and the oceanic state, and the kinematic and thermodynamic environment surrounding heavy rain producing oceanic tropical convective systems (excluding tropical cyclones). Three-hourly rainfall data from the TRMM product 3B42 are used to identify extreme precipitation events, and composites of surrounding meteorological fields are examined to understand the forcing and maintenance of these systems. Atmosphere-ocean surface heat and moisture fluxes are analyzed with corresponding meteorological fields provided by MERRA reanalyses, as well as bulk aerodynamic formulae using scatterometer data. In addition, QuikSCAT, ASCAT, and RapidSCAT are used to represent surface wind data surrounding the precipitation systems in question, and differences between MERRA and scatterometer near surface winds are investigated. The goal of this research is to understand the co-evolution of surface wind kinematic features and heavy precipitation, and their water and energy budgets in intense oceanic tropical rainfall.

  10. Regional earth-atmosphere energy balance estimates based on assimilations with a GCM

    NASA Technical Reports Server (NTRS)

    Alexander, Michael A.; Schubert, Siegfried D.

    1990-01-01

    The Oort and Vonder Haar (1976) column-budget technique is presently used to evaluate the physical consistency and accuracy of regional earth-atmosphere energy balance estimates for (1) atmospheric budget terms, (2) net radiation at the top of the atmosphere, and (3) time tendency and flux divergence of energy, for Special Observing Periods of the FGGE year. It is found that, during winter, the midlatitude oceans supply large quantities of energy to the overlying atmosphere, which then transports the energy to the continental heat-sinks; the energy flows in the opposite direction during summer.

  11. Predictability of convective precipitation for West Africa: Does the land surface influence ensemble variability as much as the atmosphere?

    NASA Astrophysics Data System (ADS)

    Maurer, Vera; Kalthoff, Norbert; Gantner, Leonhard

    2015-04-01

    In recent studies, the importance of the influence of the land surface and especially of soil-moisture heterogeneities on convective systems and convection initiation in the Sahel was established. This investigation aims at comparing the land-surface part of the influence on convection with that of the atmosphere. For this reason, realistic land-surface perturbations were generated to set up an ensemble of convection-permitting simulations that contains atmospheric as well as land-surface perturbations. The simulation of precipitation by the ensemble proved to be sufficiently realistic. By comparing precipitation forecasts of individual members, it was found that the effectiveness of soil perturbations in generating ensemble variability is as large as the effectiveness of the atmosphere. This means that the representation of the land surface, reflected by parameters such as the soil-type distribution and absolute soil moisture as well as its heterogeneities, is as important for the predictability of convective precipitation in the Sahel region as atmospheric conditions. However, soil perturbations do not determine the day on which larger convective systems occur. This rather depends on larger-scale factors such as African easterly waves, the strength of the monsoon flow as well as the location and intensity of the heat low. In each case, it is a combination of different processes determining the occurrence of convection and convective precipitation.

  12. Influence of Atmospheric Pressure Torch Plasma Irradiation on Plant Growth

    NASA Astrophysics Data System (ADS)

    Akiyoshi, Yusuke; Hayashi, Nobuya; Kitazaki, Satoshi; Koga, Kazunori; Shiratani, Masaharu

    2011-10-01

    Growth stimulation characteristics of plants seeds are investigated by an atmospheric discharge irradiation into plasma seeds. Atmospheric pressure plasma torch is consisted of alumina ceramics tube and the steel mesh electrodes wind inside and outside of the tube. When AC high voltage (8 kHz) is applied to the electrode gap, the barrier discharge plasma is produced inside the alumina ceramics tube. The barrier discharge plasma is blown outside with the gas flow in ceramics tube. Radish sprouts seeds locate at 1 cm from the torch edge. The growth stimulation was observed in the length of a stem and a root after the plasma irradiation. The stem length increases approximately 2.8 times at the cultivation time of 24 h. And the growth stimulation effect is found to be maintained for 40 h, after sowing seeds. The mechanism of the growth stimulation would be the redox reaction inside plant cells induced by oxygen radicals.

  13. Regional model studies of the atmospheric dispersion of fine volcanic ash after the eruption of Eyjafjallajoekull

    NASA Astrophysics Data System (ADS)

    Langmann, B.; Hort, M. K.

    2010-12-01

    During the eruption of Eyjafjallajoekull on Iceland in April/May 2010 air traffic over Europe was repeatedly interrupted because of volcanic ash in the atmosphere. This completely unusual situation in Europe leads to the demand of improved crisis management, e.g. European wide regulations of volcanic ash thresholds and improved forecasts of theses thresholds. However, the quality of the forecast of fine volcanic ash concentrations in the atmosphere depends to a great extent on a realistic description of the erupted mass flux of fine ash particles, which is rather uncertain. Numerous aerosol measurements (ground based and satellite remote sensing, and in situ measurements) all over Europe have tracked the volcanic ash clouds during the eruption of Eyjafjallajoekull offering the possibility for an interdisciplinary effort between volcanologists and aerosol researchers to analyse the release and dispersion of fine volcanic ash in order to better understand the needs for realistic volcanic ash forecasts. This contribution describes the uncertainties related to the amount of fine volcanic ash released from Eyjafjallajoekull and its influence on the dispersion of volcanic ash over Europe by numerical modeling. We use the three-dimensional Eulerian atmosphere-chemistry/aerosol model REMOTE (Langmann et al., 2008) to simulate the distribution of volcanic ash as well as its deposition after the eruptions of Eyjafjallajoekull during April and May 2010. The model has been used before to simulate the fate of the volcanic ash after the volcanic eruptions of Kasatochi in 2008 (Langmann et al., 2010) and Mt. Pinatubo in 1991. Comparing our model results with available measurements for the Eyjafjallajoekull eruption we find a quite good agreement with available ash concentrations data measured over Europe as well as with the results from other models. Langmann, B., K. Zakšek and M. Hort, Atmospheric distribution and removal of volcanic ash after the eruption of Kasatochi volcano: A regional model study, J. Geophys. Res., 115, D00L06, doi:10.1029/2009JD013298, 2010. Langmann, B., S. Varghese, E. Marmer, E. Vignati, J. Wilson, P. Stier and C. O’Dowd, Aerosol distribution over Europe: A model evaluation study with detailed aerosol microphysics, Atmos. Chem. Phys. 8, 1591-1607, 2008.

  14. Processes influencing rainfall features in the Amazonian region

    NASA Astrophysics Data System (ADS)

    Gerken, T.; Chamecki, M.; Fuentes, J. D.; Katul, G. G.; Fitzjarrald, D. R.; Manzi, A. O.; Nascimento dos Santos, R. M.; von Randow, C.; Stoy, P. C.; Tota, J.; Trowbridge, A.; Schumacher, C.; Machado, L.

    2014-12-01

    The Amazon is globally unique as it experiences the deepest atmospheric convection with important teleconnections to other parts of the Earth's climate system. In the Amazon Basin a large fraction of the local evapotranspiration is recycled through the formation of deep convective precipitating storms. Deep convection occurs due to moist thermodynamic conditions associated with elevated amounts of convective available potential energy. Aerosols invigorate the formation of convective storms in the Amazon via their unique concentrations, physical size, and chemical composition to activate into cloud condensation nuclei (CCN), but important aspects of aerosol/precipitation feedbacks remain unresolved. During the wet season, low atmospheric aerosol concentrations prevail in the pristine tropical air masses. These conditions have led to the Green Ocean hypothesis, which compares the clean tropical air to maritime air-masses and emphasizes biosphere-atmosphere feedbacks, to explain the features of the convective-type rainfall events in the Amazon. Field studies have been designed to investigate these relationships and the development of mesoscale convective systems through the Green Ocean Amazon project and the GOAmazon Boundary Layer Experiment. From March to October 2014 a field experiment was conducted at the Cuieiras Biological Reserve (2°51' S, 54°58' W), 80 km north of the city of Manaus, Brazil. This investigation spans the biological, chemical, and physical conditions influencing emissions and reactions of precursors (biogenic and anthropogenic volatile organic compounds, VOCs), formation of aerosols and CCNs and transport out of the ABL, and their role in cloud formation and precipitation triggers. In this presentation we will show results on the magnitude turbulent fluxes of latent and sensible heat, CCN concentrations, and rain droplet size distribution for both the wet and dry season. Such influencing factors on precipitation, will be contrasted with the vertical contoured frequency-by-altitude diagrams (CFADs) for representative mesoscale convective systems for dry and wet seasons. Rainfall yields from mesoscale convective storms will be linked to the antecedent thermodynamic conditions derived from analyses of upper air soundings.

  15. The solar atmosphere and the structure of active regions

    NASA Technical Reports Server (NTRS)

    Sturrock, P. A.

    1974-01-01

    The existence of 'holes' in the corona is reported characterized by abnormally low densities and temperatures. It was found that such coronal holes appear to be the source of high-velocity, enhanced-density streams in the solar wind as observed at the earth's orbit. It was further noted that coronal holes appear to be associated with regions of diverging magnetic fields in the corona. Models were developed to accomplish the objective for the principal energy flows in the transition region and corona.

  16. Climatic parameters of wind-field variability in the Black Sea region: Numerical reanalysis of regional atmospheric circulation

    Microsoft Academic Search

    V. V. Efimov; A. E. Anisimov

    2011-01-01

    A reanalysis of atmospheric circulation in the Black Sea region is performed with a high spatial resolution of 25 × 25 km\\u000a for the period from 1958 to 2001. Climatic wind speed fields are estimated, as are their spatial structure and seasonal variability.\\u000a Mesoscale regions of cyclonic and anticyclonic speed vorticity, which are connected with edge effects and orography, are

  17. Comparative influences of airborne pollutants and meteorological parameters on atmospheric visibility and turbidity

    NASA Astrophysics Data System (ADS)

    Wen, Chih-Chung; Yeh, Hui-Hsuan

    2010-06-01

    The purpose of this paper was to investigate how atmospheric air pollutants and meteorological conditions affect atmospheric visibility and turbidity. Meteorological parameter and anthropogenic air pollutant values were recorded during 2004 and 2005 at the Wuchi weather station and the Sha-lu environmental quality database station at the Taichung Harbor near the Taiwan Strait. Local weather conditions (temperature, relative humidity and solar radiation) and airborne pollutant (PM 10, SO 2, NO 2, CO and O 3) concentrations were used to analyze the relative effects of atmospheric air pollutants and meteorological conditions on atmospheric visibility and turbidity. Based on the analytic results, air pollutant concentrations significantly influence visibility and atmospheric turbidity. Wind speed is an important meteorological parameter that affects atmospheric turbidity parameters at the same atmospheric air pollutant concentrations throughout the periods of observation. At wind speeds of greater than 7 m/s, the turbidity factor ? Vis is below 0.3 and visibility is greater than 6.5 km. Under very turbid conditions, ? Vis > 0.4, the wind velocity is below 5 m/s, regardless of the atmospheric pollutant concentration. When visibility is ? 11 km, the PM 10 concentration is predicted to be below 150 ?g/m 3 and the atmosphere is regarded as clear. Under very turbid conditions, the PM 10 concentration exceeds 250 ?g/m 3.

  18. MODELING REGIONAL-SCALE ATMOSPHERIC MERCURY USING RELMAP

    EPA Science Inventory

    The Regional Lagrangian Model of Air Pollution (RELMAP) is used to simulate the emission, transport and diffusion, chemical transformation, and wet and dry deposition of elemental mercury gas, divalent mercury gas and particulate mercury. ased on recent modeling advances in Europ...

  19. Influence of modified atmosphere packaging on 'Star Ruby' grapefruit phytochemicals.

    PubMed

    Chaudhary, Priyanka R; Jayaprakasha, G K; Porat, Ron; Patil, Bhimanagouda S

    2015-01-28

    Modified atmosphere packaging (MAP) can extend the shelf life of salads, vegetables, and fruits by generating a storage environment with low O2, high CO2, and high humidity. The current study investigates the effect of modified atmosphere and humidity generated by two plastic films, microperforated bags (MIPBs) and macroperforated bags (MAPBs), on the levels of phytochemicals present in 'Star Ruby' grapefruits (Citrus paradisi, Macf.) stored for 16 weeks at 10 °C. Control fruits were stored without any packaging film. Juice samples were analyzed every 4 weeks for ascorbic acid, carotenoids, limonoids, flavonoids, and furocoumarins and assessed for quality parameters. MAP significantly reduced weight loss compared to control grapefruits. Control fruits had more ?-carotene, lycopene, and furocoumarin compared with the fruits in MAP. Flavonoid content was highest in fruits stored in MAPB (P < 0.05), while fruits stored in MIPB showed no significant difference in flavonoid content compared to control (P > 0.05). The MAP treatments did not significantly affect ascorbic acid, limonoids, or fruit quality parameters, including total soluble solids, acidity, ripening ratio, decay and disorders, fruit taste, and off-flavors after 16 weeks of storage. These results suggest that MAP can be used to maintain the quality of 'Star Ruby' grapefruit with no detrimental effect on health-promoting phytochemicals. PMID:25547121

  20. Influence of atmospheric pollution on the lead content of wines.

    PubMed

    Médina, B; Augagneur, S; Barbaste, M; Grousset, F E; Buat-Ménard, P

    2000-06-01

    Over the last century, the atmospheric fallout of anthropogenic lead has evolved with time, as a function of the chronological variability of transient lead inputs from both industrial and gasoline origins. This variability has been mostly documented over North America and northern Europe. In this study we used ICP-MS for the determination of lead isotope ratios and showed that a series of French wines followed the evolution of the environmental lead record over the last century. We observe the same three-step chronological evolution of the lead isotopic composition, which reflects a western European signal. In the post 1950 vintages, the lead isotope composition reflects a dominant atmospheric fallout. Since approximately 1950, Pb concentrations have been much lower than before, decreasing consistently from approximately 0.25 mg l-1 around the early 1950s, down to less than approximately 0.1 mg l-1 nowadays. Reflecting the airborne pollution, the lead isotopic signature is also specific of the continental origin of the wines and lead isotope ratios determination in wines appears to be a promising tool for certifying wine authenticity. PMID:10932786

  1. Land conversion in Amazonia and Northern South America : influences on regional hydrology and ecosystem response

    E-print Network

    Knox, Ryan Gary

    2013-01-01

    A numerical model of the terrestrial biosphere (Ecosystem Demography Model) is compbined with an atmospheric model (Brazilian Regional Atmospheric Modeling System) to investigate how land conversion in the Amazon and ...

  2. Sensitivity of Boreal-Summer Circulation and Precipitation to Atmospheric Aerosols in Selected Regions. Part 2; The Americas

    NASA Technical Reports Server (NTRS)

    Wilcox, E. M.; Sud, Y. C.; Walker, G.

    2009-01-01

    Aerosol perturbations over selected land regions are imposed in Version-4 of the Goddard Earth Observing System (GEOS-4) general circulation model (GCM) to assess the influence of increasing aerosol concentrations on regional circulation patterns and precipitation in four selected regions: India, Africa, and North and South America. Part 1 of this paper addresses the responses to aerosol perturbations in India and Africa. This paper presents the same for aerosol perturbations over the Americas. GEOS-4 is forced with prescribed aerosols based on climatological data, which interact with clouds using a prognostic scheme for cloud microphysics including aerosol nucleation of water and ice cloud hydrometeors. In clear-sky conditions the aerosols interact with radiation. Thus the model includes comprehensive physics describing the aerosol direct and indirect effects on climate (hereafter ADE and AIE respectively). Each simulation is started from analyzed initial conditions for 1 May and was integrated through June-July-August of each of the six years: 1982 1987 to provide a 6-ensemble set. Results are presented for the difference between simulations with double the climatological aerosol concentration and one-half the climatological aerosol concentration for three experiments: two where the ADE and AIE are applied separately and one in which both the ADE and AIE are applied. The ADE and AIE both yield reductions in net radiation at the top of the atmosphere and surface while the direct absorption of shortwave radiation contributes a net radiative heating in the atmosphere. A large net heating of the atmosphere is also apparent over the subtropical North Atlantic Ocean that is attributable to the large aerosol perturbation imposed over Africa. This atmospheric warming and the depression of the surface pressure over North America contribute to a northward shift of the inter-Tropical Convergence Zone over northern America, an increase in precipitation over Central America and the Caribbean, and an enhancement of convergence in the North American monsoon region.

  3. Mapping Distant Continental Influences in the Remote Pacific Atmosphere; Simulations of CO Relevant to the Photochemistry of Oxidants

    NASA Technical Reports Server (NTRS)

    Chatfield Robert B.; Guo, Z.; Sachse, G.; Singh, H.; Hipskind, R. Stephen (Technical Monitor)

    2000-01-01

    An animated sequence of maps of simulated carbon monoxide concentrations graphically portrays the extent of residual continental influence upon the tropical Pacific Ocean as studied by NASA aircraft during the PEM-Tropics B intensive sampling campaign. We used the MM5 at a 90 km resolution in a globally wrapped grid to simulate the meteorology of transport, and our GRACES model to follow the basic chemistry. The CO we simulate derives from different sources, and so we distinguish anthropogenic, natural terpenoid oxidation, biomass burning, and pervasive CH4-oxidation influences. "Influence" is always judged with an implicit timescale, and these maps describe influence on the 15-45 day timescale appropriate for CO oxidation. In consequence, the maps are useful in assessing the origins of slowly reacting compounds like acetone, methanol, and the lightest hydrocarbons. At 8 km altitude, The Eastern South Pacific to ca. 130 W (eastern Polynesia) was frequently affected by continental influences but NASA's DC-8's flight path did not happen to take it into these regions very often. Near the surface, continentally influenced air crossed into t he Western South Pacific, in the region northwest of the Southern Pacific Convergence Zone but south of the Intertropical Convergence Zone. This air originated from the NE Pacific, and partly from North America. Comparisons are made to CO and other compounds measured aboard the DC-8 and the P-3 aircraft. We will also use tracers to describe the influence of marine convection in the upper troposphere. As time allows, we will discuss the "age" of ozone within the very cleanest region sampled in portions of the near-equatorial Western South Pacific, using a simple chemical mechanism for ozone levels. These simulations describe the chemistry of an atmosphere with very low ozone.

  4. Direct impact of atmospheric CO2 enrichment on regional transpiration

    Microsoft Academic Search

    C. M. J. Jacobs

    1994-01-01

    Plant physiological research has revealed that stomatal aperture of many plant species is reduced by CO 2<\\/sub> . Therefore, the question has been raised as to how transpiration will be affected if the ambient C0 2<\\/sub> concentration increases. This study focuses on the prediction of changes in transpiration at the regional scale (10-100 km horizontal, 1-5 km vertical). A rather

  5. The influence of atmospheric stratification on scatterometer winds

    NASA Technical Reports Server (NTRS)

    Hoffman, Ross N.; Louis, Jean-Francois

    1990-01-01

    Scatterometers measure surface roughness which is empirically related either to surface stress or to the equivalent neutral stability wind. The importance of atmospheric stability effects for the analysis of these data is studied. For low wind speeds and neutral to slightly stable conditions, neutral stability wind is quite sensitive to stability. A variational analysis procedure for the scatterometer data, which adjusts both the near-surface velocity and temperature, is developed. In simulation tests, temperature analysis increments are found to be small. Also, the differences in the wind analyses due to differences in the temperature background field are small. However, if stability effects are not accounted for, there will be small systematic errors in the wind analysis.

  6. Atmospheric Extreme Events in the North Atlantic Region

    NASA Astrophysics Data System (ADS)

    Franzke, C.

    2012-04-01

    An important part of European weather and climate are storms. European winter storms cause economic damage and insurance losses on the order of billions of Euro per year. European winter storms rank as the second highest cause of global natural catastrophe insurance loss. Many of these hazard events are not independent; for instance, severe storms can occur in trains of storms. Recent examples of such subsequently occurring storms include January 2008 (Paula and Resi) and March 2008 (Emma, Johanna and Kirsten). Each of these trains of storms caused damages on the order of ~€1bn. Extreme value statistics are based on the premise that extreme events are iid but this is rarely the case in natural systems where extreme events tend to cluster. Thus, no account is taken of memory and correlation that characterise many natural time series; this fundamentally limits our ability to forecast and to estimate return periods of extreme events. In my presentation I will discuss two possible causes of this clustering: (i) The propensity of extreme events to depend on large-scale circulation regimes and (ii) the long-range correlation properties of surface windspeeds enhances the likelihood of extreme events to cluster. These two characteristics affect the return periods of atmospheric extreme events and thus insurance pricing.

  7. Spatial extent of the North American Monsoon: Increased cross-regional linkages via atmospheric pathways

    NASA Astrophysics Data System (ADS)

    Dominguez, Francina; Villegas, Juan Camilo; Breshears, David D.

    2009-04-01

    The North American monsoon is a key feature affecting summer climate over Southwestern North America. During the monsoon, evapotranspiration from the Southwest promotes transference of water to the atmosphere which is subsequently distributed across the continent - linking the SW to other regions via atmospheric hydrologic connectivity. However, the degree to which atmospheric connectivity redistributes monsoonal terrestrial moisture throughout the continent and its sensitivity to climate disturbances such as drought is uncertain. We tracked the trajectory of moisture evapotranspired within the semiarid Southwest during the monsoon season using a Lagrangian analytical model. Southwest moisture was advected north-east accounting for ˜15% of precipitation in adjacent Great Plains regions. During recent drought (2000-2003), this amount decreased by 45%. Our results illustrate that the spatial extent of the North American monsoon is larger than normally considered when accounting for hydrologic connectivity via soil moisture redistribution through atmospheric pathways.

  8. Regional Atmospheric Transport Code for Hanford Emission Tracking, Version 2(RATCHET2)

    SciTech Connect

    Ramsdell, James V.; Rishel, Jeremy P.

    2006-07-01

    This manual describes the atmospheric model and computer code for the Atmospheric Transport Module within SAC. The Atmospheric Transport Module, called RATCHET2, calculates the time-integrated air concentration and surface deposition of airborne contaminants to the soil. The RATCHET2 code is an adaptation of the Regional Atmospheric Transport Code for Hanford Emissions Tracking (RATCHET). The original RATCHET code was developed to perform the atmospheric transport for the Hanford Environmental Dose Reconstruction Project. Fundamentally, the two sets of codes are identical; no capabilities have been deleted from the original version of RATCHET. Most modifications are generally limited to revision of the run-specification file to streamline the simulation process for SAC.

  9. Permafrost Thaw and Redistribution of Carbon from Lands and Oceans to the Atmosphere: the East Siberian Region

    NASA Astrophysics Data System (ADS)

    Semiletov, I. P.; Shakhova, N. E.; Pipko, I.; Dudarev, O.; Charkin, A.

    2014-12-01

    Unlike other oceans, the Arctic Ocean is completely surrounded by permafrost, which is being degraded at an increasing rate under warming conditions most pronounced in East Siberian region and Alaska. The thaw and release of organic carbon (OC) from Arctic permafrost is postulated to be one of the most powerful mechanisms causing the net redistribution of carbon from lands and oceans to the atmosphere. The East Siberian Arctic shelf (ESAS) is the world's largest continental shelf, containing more than 80 % of the world oceans' subsea permafrost and the largest hydrocarbon reservoir on the planet, while the stability of this sequestered carbon, which exists primarily as CH4, is highly uncertain. This area is heavily influenced by subsea permafrost thaw, and CH4 seeps from subsea permafrost reservoirs under warming conditions. Various other phenomena influence the area, including coastal erosion, mostly caused by onshore permafrost/coastal ice complex thaw; the input of dissolved and particulate OC through the Lena, Indigirka, and Kolyma rivers. The ESAS is also of particular interest for its carbon-climate couplings because thawing of onshore and offshore permafrost leads to the CH4 and CO2 emission to the atmosphere. The overall goal of the current research is to provide a quantitative, observation-based assessment of the dynamics of different ESAS carbon cycle components with emphasize on the emission of CO2 and CH4 to the atmosphere under changing climatic and environmental conditions.

  10. Assessment of regional seasonal rainfall predictability using the CPTEC\\/COLA atmospheric GCM

    Microsoft Academic Search

    J. A. Marengo; I. F. A. Cavalcanti; P. Satyamurty; I. Trosnikov; C. A. Nobre; J. P. Bonatti; H. Camargo; G. Sampaio; M. B. Sanches; A. O. Manzi; C. A. C. Castro; C. D'Almeida; L. P. Pezzi; L. Candido

    2003-01-01

    This is a study of the annual and interannual variability of regional rainfall produced by the Center for Weather Forecasts and Climate Studies\\/Center for Ocean, Land and Atmospheric Studies (CPTEC\\/COLA) atmospheric global climate model. An evaluation is made of a 9-member ensemble run of the model forced by observed global sea surface temperature (SST) anomalies for the 10-year period 1982–1991.

  11. Influence of ocean surface conditions on atmospheric vertical thermodynamic structure and deep convection

    SciTech Connect

    Fu, Rong (California Institute of Technology, Pasadena, CA (United States)); Del Genio, A.D.; Rossow, W.B. (NASA/Goddard Space Flight Center, New York, NY (United States))

    1994-07-01

    The influence of sea surface temperature (SST) and surface wind divergence on atmospheric thermodynamic structure is analysed along with the resulting effects on the occurrence of deep convection using National Meterological Center radiosonde data and International Satellite Cloud Climatology Program data for July 1983-July 1985. The onset of deep convection requires not only the existence of positive convective available potential energy (CAPE), but also unstable planetary boundary layer (PBL). A stable PBL is observed to suppress deep convection even when CAPE is positive. Variations of SSt have a major effect on CAPE, but surface wind divergence can also affect deep convection by changing the lapse rate in the lower troposphere and humidity in the PBL. In warm SST regions, CAPE > 0 regardless of assumptions about condensate loading. When SST <27[degrees]C, CAPE layer and moisten the PBL enough to make the atmosphere neutrally stable in the mean. As a result, deep convection is generally enhanced either when SST [>=] 28[degrees]C in the absence of strong surface wind divergence or when strong surface wind convergence occurs even if SST < 27[degrees]. The anomalous suppression wind divergence or when strong surface wind convergence occurs even if SST < 27[degrees]C. The anomalous suppression of deep convection in the warm area of the equatorial west Pacific lying between the ITCZ and SPCZ is probably caused by dryness in the PBL and an inversion in that area. The seasonal cycles of deep convection and surface wind divergence are in phase with the maximum solar radiation and lead SST for one to three months in the central Pacific. The change of PBL relative humidity plays a critical role in the changeover to convective instability in this case. The seasonal change of deep convection and associated clouds seems not to have important effects on the seasonal change of local SST in the central Pacific. 37 refs., 11 figs., 1 tab.

  12. Influence of solar magnetic sector structure on terrestrial atmosphere vorticity

    NASA Technical Reports Server (NTRS)

    Wilcox, J. M.; Scherrer, P. H.; Svalgaard, L.; Roberts, W. O.; Olson, R. H.; Jenne, R. L.

    1973-01-01

    The solar magnetic sector structure has a sizable and reproducible influence on tropospheric and lower stratospheric vorticity. The average vorticity during winter in the Northhern Hemisphere north of 20 deg N latitude reaches a minimum approximately one day after the passing of a sector boundary, and then increases during the following two or three days. The effect is found at all heights within the troposphere, but is not prominent in the stratosphere, except at the lower levels. No single longitudinal interval appears to dominate the effect.

  13. Influence of solar magnetic sector structure on terrestrial atmospheric vorticity

    NASA Technical Reports Server (NTRS)

    Wilcox, J. M.; Scherrer, P. H.; Svalgaard, L.; Roberts, W. O.; Olson, R. H.; Jenne, R. L.

    1974-01-01

    The solar magnetic sector structure has a sizable and reproducible influence on tropospheric and lower stratospheric vorticity. The average vorticity during winter in the Northern Hemisphere north of 20N latitude reaches a minimum approximately one day after the passing of a sector boundary, and then increases during the following two or three days. The effect is found at all heights within the troposphere, but is not prominent in the stratosphere, except at the lower levels. No single longitudinal interval appears to dominate the effect.

  14. Flood regionalization: A hybrid geographic and predictor-variable region-of-influence regression method

    USGS Publications Warehouse

    Eng, K.; Milly, P.C.D.; Tasker, Gary D.

    2007-01-01

    To facilitate estimation of streamflow characteristics at an ungauged site, hydrologists often define a region of influence containing gauged sites hydrologically similar to the estimation site. This region can be defined either in geographic space or in the space of the variables that are used to predict streamflow (predictor variables). These approaches are complementary, and a combination of the two may be superior to either. Here we propose a hybrid region-of-influence (HRoI) regression method that combines the two approaches. The new method was applied with streamflow records from 1,091 gauges in the southeastern United States to estimate the 50-year peak flow (Q50). The HRoI approach yielded lower root-mean-square estimation errors and produced fewer extreme errors than either the predictor-variable or geographic region-of-influence approaches. It is concluded, for Q50 in the study region, that similarity with respect to the basin characteristics considered (area, slope, and annual precipitation) is important, but incomplete, and that the consideration of geographic proximity of stations provides a useful surrogate for characteristics that are not included in the analysis. ?? 2007 ASCE.

  15. Influence of atmospheric boundary layer on turbulence in wind turbine wake

    NASA Astrophysics Data System (ADS)

    Debnath, Mithu Chandra

    Full-scale wind turbines (WT) operate in the atmospheric boundary layer. The atmospheric boundary layer structure significantly influences the turbulence generated in the wake of the WT. As Atmospheric boundary layer structure is dictated by the stratification of the atmosphere, hence stratifications effects are critical in accurate representation of the turbine wake physics. Due to the dependency of several factors, such as turbulence scales, buoyancy flux, momentum flux, the atmospheric boundary layer turbulence capturing is really challenging. Large Eddy Simulation (LES) has been used as a tool to understand the effects of atmospheric stability on turbine wake turbulence. The differences between the stable and unstable atmosphere on wake of 5-MW turbine has been explored. Differences in tip and root vortex interactions, wake expansion and recovery have been analyzed. The study has revealed for stable ABL low level jets play an important role in wake dynamics and increasing stability delays the wake recovery. Tip vortex is unconditionally unstable in all stability conditions due to mutual inductance mode of stability leading to vortex merging. The study is one of the first studies that accounts for realistic atmospheric boundary turbulence on wake development.

  16. Modeling evaporation from porous media influenced by atmospheric processes

    NASA Astrophysics Data System (ADS)

    Mosthaf, K.; Baber, K.; Flemisch, B.; Helmig, R.

    2012-04-01

    Modeling evaporation processes from partially saturated soils into the ambient air is a challenging task. It involves usually a variety of interacting processes and depends on the multitude of properties of the fluids and of the porous medium. Often, the ambient free-flow and the porous-medium compartments are modeled separately with a specification of the evaporation rate as boundary condition. We have developed a coupling concept, which allows the combined modeling of a free-flow and a porous-medium system under non-isothermal conditions with the evaporative fluxes across the soil-atmosphere interface as model output. It is based on flux continuity and local thermodynamic equilibrium at the interface. Darcy's law for multiple phases is used in the porous medium, whereas the ambient air flow is modeled as a compositional single-phase Stokes system. The concept has been implemented in the numerical simulator DuMux. A comparison of simulated and measured data from wind tunnel experiments performed in the group of D. Or (ETH Zürich) will be shown. Furthermore, the impact of several parameters, such as a varying wind velocity, temperature or different soil properties on the evaporation process has been analyzed in a numerical parameter study. The results will be presented and discussed.

  17. The local and regional atmospheric oxidants at Athens (Greece).

    PubMed

    Varotsos, C A; Ondov, J M; Efstathiou, M N; Cracknell, A P

    2014-03-01

    In the present study, the investigation of the levels of the local and regional oxidants concentration at Athens, Greece, is attempted by analyzing the observations obtained at an urban and a rural station, during 2001-2011 and 2007-2011, respectively. A progressive increase of the daytime and nighttime average of [NO2]/[Ox] versus [NOx] is observed showing a larger proportion of Ox in the form of NO2 when the level of NOx increases. Similar results are observed when studying the variation of mean values of [NO2]/[NOx] versus [NOx]. The results obtained when compared with those that have earlier detected elsewhere, revealed similarities and discrepancies that are discussed in detail. The parameterized curves that are presented for the first time in this paper may be used by the air quality planners to track the trends in other cities also, and to understand what is or was driving them. PMID:24327116

  18. Fruit Maturity and Storage Temperature Influence Response of Strawberries to Controlled Atmospheres

    Microsoft Academic Search

    M. C. N. Nunes; A. M. M. B. Morais; J. K. Brecht; S. A. Sargent

    2002-01-01

    Chandler' strawberries (Fragaria ×ananassa Duch.) harvested three-quarter colored or fully red were stored in air or a controlled atmosphere (CA) of 5% O2 + 15% CO2 at 4 or 10 °C to evaluate the influence of fruit maturity and storage temperature on the response to CA. Quality evaluations were made after 1 and 2 weeks in air or CA, and

  19. ea surface temperature (SST) influences the atmosphere through its effects on sensible and

    E-print Network

    Kurapov, Alexander

    #12;#12;S ea surface temperature (SST) influences the atmosphere through its effects on sensible) models. On large scales, SST is negatively correlated with surface winds, which has been inter- preted and Ekman advection of the mean SST gradi- ents (e.g., Mantua et al. 1997; Okumura et al. 2001; Tomita et al

  20. Influence of Elevated Atmospheric Carbon Dioxide on Transcriptional Responses of Bradyrhizobium japonicum in the Soybean Rhizoplane

    PubMed Central

    Sugawara, Masayuki; Sadowsky, Michael J.

    2013-01-01

    Elevated atmospheric CO2 can influence the structure and function of rhizoplane and rhizosphere microorganisms by altering root growth and the quality and quantity of compounds released into the rhizoplane and rhizosphere via root exudation. In these studies we investigated the transcriptional responses of Bradyrhizobium japonicum cells growing in the rhizoplane of soybean plants exposed to elevated atmospheric CO2. The results of microarray analyses indicated that elevated atmospheric CO2 concentration indirectly influenced the expression of a large number of genes in Bradyrhizobium attached to soybean roots. In addition, relative to plants and bacteria grown under ambient CO2 growth conditions, genes involved in C1 metabolism, denitrification and FixK2-associated genes, including those involved in nitrogen fixation, microaerobic respiration, respiratory nitrite reductase, and heme biosynthesis, were significantly up-regulated under conditions of elevated CO2 in the rhizosphere. The expression profile of genes involved in lipochitooligosaccharide Nod factor biosynthesis and negative transcriptional regulators of nodulation genes, nolA and nodD2, were also influenced by plant growth under conditions of elevated CO2. Taken together, the results of these studies indicate that the growth of soybeans under conditions of elevated atmospheric CO2 influences gene expressions in B. japonicum in the soybean rhizoplane, resulting in changes to carbon/nitrogen metabolism, respiration, and nodulation efficiency. PMID:23666536

  1. Do organic surface films on sea salt aerosols influence atmospheric chemistry? - a model study

    Microsoft Academic Search

    L. Smoydzin; R. von Glasow

    2007-01-01

    Organic material from the ocean's surface can be incorporated into sea salt aerosol particles often producing a surface film on the aerosol. Such an organic coating can reduce the mass transfer between the gas phase and the aerosol phase influencing sea salt chemistry in the marine atmosphere. To investigate these effects and their importance for the marine boundary layer (MBL)

  2. Influence of Ocean Surface Conditions on Atmospheric Vertical Thermodynamic Structure and Deep Convection

    Microsoft Academic Search

    Rong Fu; Anthony D. del Genio; William B. Rossow

    1994-01-01

    The authors analyze the influence of sea surface temperature (SST) and surface wind divergence on atmospheric thermodynamic structure and the resulting effects on the occurrence of deep convection using National Meteorological Center radiosonde data and International Satellite Cloud Climatology Program data for July 1983-July 1985. The onset of deep convection requires not only the existence of positive convective available potential

  3. Influence of ocean surface conditions on atmospheric vertical thermodynamic structure and deep convection

    Microsoft Academic Search

    Rong Fu; Anthony D. Del Genio; William B. Rossow

    1994-01-01

    The influence of sea surface temperature (SST) and surface wind divergence on atmospheric thermodynamic structure is analysed along with the resulting effects on the occurrence of deep convection using National Meterological Center radiosonde data and International Satellite Cloud Climatology Program data for July 1983-July 1985. The onset of deep convection requires not only the existence of positive convective available potential

  4. Author's personal copy Pollution influences on atmospheric composition and chemistry at high

    E-print Network

    Jimenez, Jose-Luis

    were quantified and found to be broadly comparable. Greenhouse gas emission estimates derived fromAuthor's personal copy Pollution influences on atmospheric composition and chemistry at high northern latitudes: Boreal and California forest fire emissions H.B. Singh a,*, B.E. Anderson b , W

  5. Influence of atmospheric deposition on Okefenokee National Wildlife Refuge

    SciTech Connect

    Winger, P.V.; Lasier, P.J. [National Biological Service, Athens, GA (United States); Jackson, B.P. [Univ. of Georgia, Athens, GA (United States)

    1995-12-31

    Designation of Okefenokee National Wildlife Refuge (Georgia) as a Class 1 Air Quality Area affords mandatory protection of the airshed through permit-review processes for planned developments. Rainfall is the major source of water to the swamp, and potential impacts from developments in the airshed are high. To meet management needs for baseline information, chemical contributions from atmospheric deposition and partitioning of anions and cations in various matrices of the swamp, with emphasis on mercury and lead, were determined during this study. Chemistry of rainfall was measured on an event basis from one site and quarterly on surface water, pore water, floc, and sediment from four locations. A sediment core collected from the Refuge concentrations of 9 ng/L and 0.1 ng/L, respectively. Surface waters were acidic (pH 4.7--4.9), with average total and methyl mercury highly organic (dissolved organic carbon 35--50 mg/L). Total mercury was 1--3.5 ng/L in surface and pore water, and methyl mercury was 0.02--0.20 ng/L. Total mercury in sediments and floc was 100--200 ng/g dry weight, and methyl mercury was 4--16ng/g. Lead was 0--1.7 {micro}g/L in rainfall, not detectable in surface water, 3.4--5.4 {micro}g/L in pore water, and 3.9--4.9 mg/kg in floc and sediment. Historical patterns of mercury deposition showed an increase in total mercury from pre-1800 concentrations of 250 ng/g to 500 ng/g in 1950, with concentrations declining thereafter to present.

  6. Simulation of Arctic Climate with the Regional Arctic System Model (RASM): Sensitivity to Atmospheric Processes

    NASA Astrophysics Data System (ADS)

    Cassano, J. J.; Duvivier, A.; Hughes, M.; Roberts, A.; Brunke, M.; Craig, A.; Fisel, B. J.; Gutowski, W. J., Jr.; Maslowski, W.; Nijssen, B.; Osinski, R.; Zeng, X.

    2014-12-01

    A new regional Earth system model of the Arctic, the Regional Arctic System Model (RASM), has recently been developed. The initial version of this model includes atmosphere (WRF), ocean (POP), sea ice (CICE), and land (VIC) component models coupled with the NCAR CESM CPL7 coupler. The model is configured to run on a large pan-Arctic domain that includes all sea ice covered waters in the Northern Hemisphere and all Arctic Ocean draining land areas. Results from multi-decadal (1979 to present) simulations with RASM will be presented and will focus on the model climate's sensitivity to atmospheric processes and a comparison of the fully coupled model and atmosphere-only simulations. The modeled radiation budget, and sea ice cover, was found to be sensitive to the details of the cloud and radiation parameterizations in the atmospheric component (WRF) of RASM, including details of cloud droplet size. Another model sensitivity was found in relation to atmosphere-land processes. Care is needed to ensure that decoupling between the atmosphere and land do not occur under strongly stable conditions over land areas in winter. Comparison of RASM near surface climate with that simulated with stand-alone WRF show areas of both improved and degraded results. Improvement in the coupled model climate are related to more physically realistic representation of coupled processes such as energy transfer from the ocean to the atmosphere through leads in the sea ice during winter. Degraded results come from feedbacks in model component biases, such as atmospheric circulation biases resulting in incorrect local sea ice cover that then result in large local atmospheric temperature biases.

  7. Influence of stochastic sea ice parametrization on climate and the role of atmosphere–sea ice–ocean interaction

    PubMed Central

    Juricke, Stephan; Jung, Thomas

    2014-01-01

    The influence of a stochastic sea ice strength parametrization on the mean climate is investigated in a coupled atmosphere–sea ice–ocean model. The results are compared with an uncoupled simulation with a prescribed atmosphere. It is found that the stochastic sea ice parametrization causes an effective weakening of the sea ice. In the uncoupled model this leads to an Arctic sea ice volume increase of about 10–20% after an accumulation period of approximately 20–30 years. In the coupled model, no such increase is found. Rather, the stochastic perturbations lead to a spatial redistribution of the Arctic sea ice thickness field. A mechanism involving a slightly negative atmospheric feedback is proposed that can explain the different responses in the coupled and uncoupled system. Changes in integrated Antarctic sea ice quantities caused by the stochastic parametrization are generally small, as memory is lost during the melting season because of an almost complete loss of sea ice. However, stochastic sea ice perturbations affect regional sea ice characteristics in the Southern Hemisphere, both in the uncoupled and coupled model. Remote impacts of the stochastic sea ice parametrization on the mean climate of non-polar regions were found to be small. PMID:24842027

  8. Influence of stochastic sea ice parametrization on climate and the role of atmosphere-sea ice-ocean interaction.

    PubMed

    Juricke, Stephan; Jung, Thomas

    2014-06-28

    The influence of a stochastic sea ice strength parametrization on the mean climate is investigated in a coupled atmosphere-sea ice-ocean model. The results are compared with an uncoupled simulation with a prescribed atmosphere. It is found that the stochastic sea ice parametrization causes an effective weakening of the sea ice. In the uncoupled model this leads to an Arctic sea ice volume increase of about 10-20% after an accumulation period of approximately 20-30 years. In the coupled model, no such increase is found. Rather, the stochastic perturbations lead to a spatial redistribution of the Arctic sea ice thickness field. A mechanism involving a slightly negative atmospheric feedback is proposed that can explain the different responses in the coupled and uncoupled system. Changes in integrated Antarctic sea ice quantities caused by the stochastic parametrization are generally small, as memory is lost during the melting season because of an almost complete loss of sea ice. However, stochastic sea ice perturbations affect regional sea ice characteristics in the Southern Hemisphere, both in the uncoupled and coupled model. Remote impacts of the stochastic sea ice parametrization on the mean climate of non-polar regions were found to be small. PMID:24842027

  9. Influence of Penning effect on the plasma features in a non-equilibrium atmospheric pressure plasma jet

    E-print Network

    Zexian, Cao

    Influence of Penning effect on the plasma features in a non-equilibrium atmospheric pressure plasma March 2014) Non-equilibrium atmospheric pressure plasma jet (APPJ) is a cold plasma source that promises possibilities of plasma sources under investigation, the non-equilibrium atmospheric pressure plasma jet (APPJ

  10. Use of a regional atmospheric model to simulate lake-atmosphere feedbacks associated with Pleistocene Lakes Lahontan and Bonneville

    USGS Publications Warehouse

    Hostetler, S.W.; Giorgi, F.

    1992-01-01

    A regional model of the atmosphere (version 4 of the NCAR mesoscale model, MM4) was used to assess whether lake-effect precipitation was a significant component of the late-Pleistocene hydrologic budgets of Lakes Lahontan and Bonneville. Control simulations for January and July of 1979 were made using MM4, and the Pleistocene highstand surface areas of the lakes were added to the model and the simulations repeated. In the January simulations, 18% of the moisture added to the modeled atmosphere by Lake Lahontan returned to the Lahontan basin as precipitation, while 32% of the water evaporated from Lake Bonneville fell as precipitation over the Bonneville basin. In the July simulations, 7% of the moisture added to the modeled atmosphere by Lake Lahontan returned to the Lahontan basin as precipitation, and 4% of the water evaporated from Lake Bonneville fell as precipitation over the Bonneville basin. An additonal January simulation was made with the lake surface areas set at onehalf their highstand extents (the average surface area 20 to 15 ka BP). Results from this simulation were similar to the simulation with the highstand lakes, indicating lake-effect precipitation could have been a significant component of the hyrologic budgets of the lakes before and during the highstand period. ?? 1992 Springer-Verlag.

  11. Atmospheric trace elements over source regions for Chinese dust: concentrations, sources and atmospheric deposition on the Loess plateau

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoye; Arimoto, Richard; An, Zhisheng; Chen, Tuo; Zhang, Guangyu; Zhu, Guanghua; Wang, Xinfu

    The mass-particle size distributions of up to 17 trace elements in aerosol particle samples from dust storm and non-dust storm periods were determined for three sites in or near the source regions of Chinese dust. The mass of particulate material in the atmosphere at the sites is dominated by mineral aerosol particles. An absolute principal component analysis of the non-dust storm elemental data for the loess region allows the estimation of the mass contributions from two coarse-particle classes (soil dust and dust associated with pollutants), and two fine-particle classes (soil dust and anomalously enriched). For most elements (Al, Si, Ca, Fe, Ti, K, S and As), the mass-particle size distributions (MSDs) were approximately log-normal. The mass-median diameters (MMDs) of the soil-derived elements tended to decrease with distance from the desert region and when the dust storms subsided. Total dry deposition velocities were calculated by fitting a log-normal distribution to the aerosol data and calculating deposition rates for 100 particle-size intervals using a two-layer deposition model. The mean dry-deposition rates and fluxes were highest during dust storms over desert regions. In thloess region, the calculated dry deposition velocities of soil derived elements (Al, Si, Ca, Fe and Ti) during non-dust storm periods were from 3.1 to 3.7 cm s -1. From the estimated mass-particles size distributions, the coarser and finer mineral particles were found to benriched with Ca, Fe, Ti and K relative to Al or Si. On a yearly basis, the dry atmospheric input to the Loess Plateau was mainly attributable to normal transport processes, i.e. non-dust storm conditions. Wet deposition fluxes estimated from scavenging ratios indicate that dry deposition dominated the total atmospheric deposition of mineral aerosol. The deposition of aerosol particles associated with coal burning or other anthropogenic sources also was considerable on the Loess Plateau.

  12. The importance of source configuration in quantifying footprints of regional atmospheric sulphur deposition

    E-print Network

    impacts for future emissions scenarios; they can be used to attribute pollutant emissions sourcesThe importance of source configuration in quantifying footprints of regional atmospheric sulphur, as well as for a 2010 emissions scenario. The 2010 emissions scenario has been chosen to simulate

  13. Numerical experiment on the effects of regional atmospheric pollution on global climate

    Microsoft Academic Search

    L. Randall Koenig

    1975-01-01

    The 1973 Rand version of the Mintz-Arakawa model of the general circulation of the atmosphere was used to study the consequences of high concentrations of hygroscopic aerosols in a limited geographic region. The experiment was designed to investigate effects of the activity of the aerosol as condenstion nuclei and the consequent abnormal production of cloudiness and alteration of precipitation were

  14. A Numerical Experiment on the Effects of Regional Atmospheric Pollution on Global Climate

    Microsoft Academic Search

    L. Randall Koenig

    1975-01-01

    The 1973 Rand version of the Mintz-Arakawa model of the general circulation of the atmosphere was used to study the consequences of high concentrations of hygroscopic aerosols in a limited geographic region. The experiment was designed to investigate effects of the activity of the aerosol as condensation nuclei and the consequent abnormal production of cloudiness and alteration of precipitation were

  15. Longitudinal variation of the E-region electric fields caused by atmospheric tides

    Microsoft Academic Search

    S. L. England; S. Maus; T. J. Immel; S. B. Mende

    2006-01-01

    demonstrated that this could be explained by a longitudinal variation in the diurnal amplitude of atmospheric tides in the E-region ionosphere. An increase in the observed separation of the airglow arcs and a coincident strong increase in the peak ion density in the arcs is indicative of an effect that takes place while ion production is still occurring, such as

  16. The influence of atmospheric turbulence on 3D flash lidar range imagery

    NASA Astrophysics Data System (ADS)

    Zhao, Yan; Han, Shaokun; Zhao, Wen; Wang, Ping; Xia, Wenze

    2013-12-01

    Three dimensional flash imaging lidar technology is widely used in the field of military and national economic construction. The preliminary simulation research is an indispensable aspect in the design of the new lidar. In order to establish a simulation model most close to the real scene, the spatial effect of the simulation system during the laser roundtrip transmission process must be considered. This paper describes the physical mechanism of the formation of atmospheric turbulence, the power spectral density function of the distribution of atmospheric refractive index and the phase distortion due to atmospheric disturbances during light propagation in space. Then the phase-screen distribution of atmospheric turbulence is derived using power spectrum retrieval and time-dependent wavefront tilt parameter. In addition, numerical simulation is conducted using statistical methods. A three dimensional target range imaging simulation model containing laser characteristics, target characteristics, receiver characteristics and laser speckle is established. And the phase screen is introduced into the calculation model to simulate the results in turbulent atmosphere. The major contribution of this paper is transforming the influence of beam spreading and drifting caused by laser propagation in turbulent flow to the influence of target range imaging, which better reveals the diffusion and position drift of imaging on detection surface caused by turbulence. Results show that larger values of refractive index structure parameters and lidar target distance produce blurry and drifting imagery.

  17. The solar wind and its influence on the atmospheres of moon, Mercury and Venus

    NASA Technical Reports Server (NTRS)

    Hartle, R. E.

    1976-01-01

    The solar wind is expected to have an important influence on the atmospheres of the moon, Mercury and Venus and therefore a brief outline of solar wind theory is presented along with the predicted properties of the wind at the orbits of these planets. Since the atmospheres of the moon and possibly Mercury are formed primarily by solar wind accretion, we present the latest accretion models for these bodies. The expected role the solar wind plays on both the ionization and termination of the ionosphere of Venus is discussed.

  18. The influence of several changes in atmospheric states over semi-arid areas on the incidence of mental health disorders

    NASA Astrophysics Data System (ADS)

    Yackerson, Naomy S.; Zilberman, Arkadi; Todder, Doron; Kaplan, Zeev

    2011-05-01

    The incidence of suicide attempts [Deliberate Self Harm (DSH); ICD-10: X60-X84] and psychotic attacks (PsA; ICD-10, F20-F29) in association with atmospheric states, typical for areas close to big deserts, was analyzed. A retrospective study is based on the 4,325 cases of DSH and PsA registered in the Mental Health Center (MHC) of Ben-Gurion University (Be'er-Sheva, Israel) during 2001-2003. Pearson and Spearman test correlations were used; the statistical significance was tested at p < 0.1. The influence of temperature and humidity on suicide attempts ( N SU ) and psychotic attacks ( N PS ) was weakly pronounced ( p > 0.1). Correlation coefficients between N SU and N PS and speed WS of westerly wind reaches 0.3 ( p < 0.05), while their dependence on easterly WS was weaker ( p > 0.09). Variations in easterly wind direction WD influence N SU and N PS values ( p < 0.04), but no corresponding correlation with westerly winds was found ( p > 0.3). Obviously ,in transition areas located between different regions ,the main role of air streams in meteorological-biological impact can scarcely be exaggerated. An unstable balance in the internal state of a weather-sensitive person is disturbed when the atmospheric state is changed by specific desert winds, which can provoke significant perturbations in meteorological parameters. Results indicate the importance of wind direction, defining mainly the atmospheric situation in semi-arid areas: changes in direction of the easterly wind influence N SU and N PS , while changes in WS are important for mental health under westerly air streams. Obviously, N SU and N PS are more affected by the disturbance of weather from its normal state, for a given season, to which the local population is accustomed, than by absolute values of meteorological parameters.

  19. Influence of flowing helium gas on plasma plume formation in atmospheric pressure plasma

    NASA Astrophysics Data System (ADS)

    Yambe, Kiyoyuki; Konda, Kohmei; Ogura, Kazuo

    2015-05-01

    We have studied atmospheric pressure plasma generated using a quartz tube, helium gas, and a foil electrode by applying RF high voltage. The atmospheric pressure plasma in the form of a bullet is released as a plume into the atmosphere. The helium gas flowing out of quartz tube mixes with air, and the flow channel is composed of the regions of flowing helium gas and air. The plasma plume length is equivalent to the reachable distance of flowing helium gas. Although the amount of helium gas on the flow channel increases by increasing the inner diameter of quartz tube at the same gas flow velocity, the plasma plume length peaks at around 8 m/s of gas flow velocity, which is the result that a flow of helium gas is balanced with the amount of gas. The plasma plume is formed at the boundary region where the flow of helium gas is kept to the wall of the air.

  20. Evaluating Observation Influence on Regional Water Budgets in Reanalyses

    NASA Technical Reports Server (NTRS)

    Bosilovich, Michael G.; Chern, Jiun-Dar; Mocko, David; Robertson, Franklin R.; daSilva, Arlindo M.

    2014-01-01

    The assimilation of observations in reanalyses incurs the potential for the physical terms of budgets to be balanced by a term relating the fit of the observations relative to a forecast first guess analysis. This may indicate a limitation in the physical processes of the background model, or perhaps inconsistencies in the observing system and its assimilation. In the MERRA reanalysis, an area of long term moisture flux divergence over land has been identified over the Central United States. Here, we evaluate the water vapor budget in this region, taking advantage of two unique features of the MERRA diagnostic output; 1) a closed water budget that includes the analysis increment and 2) a gridded diagnostic output data set of the assimilated observations and their innovations (e.g. forecast departures). In the Central United States, an anomaly occurs where the analysis adds water to the region, while precipitation decreases and moisture flux divergence increases. This is related more to a change in the observing system than to a deficiency in the model physical processes. MERRAs Gridded Innovations and Observations (GIO) data narrow the observations that influence this feature to the ATOVS and Aqua satellites during the 06Z and 18Z analysis cycles. Observing system experiments further narrow the instruments that affect the anomalous feature to AMSUA (mainly window channels) and AIRS. This effort also shows the complexities of the observing system, and the reactions of the regional water budgets in reanalyses to the assimilated observations.

  1. Distinct atmospheric patterns and associations with acute heat-induced mortality in five regions of England

    NASA Astrophysics Data System (ADS)

    Petrou, Ilias; Dimitriou, Konstantinos; Kassomenos, Pavlos

    2015-01-01

    The main objective of this paper was to identify possible acute heat-induced summer mortality in five regions of England namely the Yorkshire and the Humber, West Midlands, North East, North West and South East regions and reveal associations with specific air flows. For this purpose, backward air mass trajectories corresponding to daily episodes of increased temperatures were produced and divided to clusters, in order to define atmospheric pathways associated with warm air mass intrusions. A statistically significant at 95 % confidence interval increase in daily total mortality (DTMORT) was observed during the selected episodes at all five regions and thus, heat-induced mortality was indicated. The calculated raise was more intense in the West Midlands, North West and South East regions, whereas the results in the North East and Yorkshire and the Humber regions were less evident. Large fractions of thermal episodes, elevated average temperature values and higher average DTMORT levels were primarily associated with the short-medium range South West (SW) and/or East-South East (E-SE) trajectory clusters, suggesting relations among heat-induced mortality and specific atmospheric circulations. Short-medium length of SW and E-SE airflows, calculated by an application of Haversine formula along the centroid trajectory of each cluster, implies the arrival of slow moving air masses. Atmospheric stagnation could enhance human thermal stress due to low wind speed.

  2. Influence of equatorial diatom processes on Si deposition and atmospheric CO2 cycles at glacial/interglacial timescales

    NASA Astrophysics Data System (ADS)

    Dugdale, R. C.; Lyle, M.; Wilkerson, F. P.; Chai, F.; Barber, R. T.; Peng, T.-H.

    2004-09-01

    The causes of the glacial cycle remain unknown, although the primary driver is changes in atmospheric CO2, likely controlled by the biological pump and biogeochemical cycles. The two most important regions of the ocean for exchange of CO2 with the atmosphere are the equatorial Pacific and the Southern Ocean (SO), the former a net source and the latter a net sink under present conditions. The equatorial Pacific has been shown to be a Si(OH)4-limited ecosystem, a consequence of the low source Si(OH)4 concentrations in upwelled water that has its origin in the SO. This teleconnection for nutrients between the two regions suggests an oscillatory relationship that may influence or control glacial cycles. Opal mass accumulation rate (MAR) data and ?15N measurements in equatorial cores are interpreted with predictions from a one-dimensional Si(OH)4-limited ecosystem model (CoSINE) for the equatorial Pacific. The results suggest that equatorial Pacific surface CO2 processes are in opposite phase to that of the global atmosphere, providing a negative feedback to the glacial cycle. This negative feedback is implemented through the effect of the SO on the equatorial Si(OH)4 supply. An alternative hypothesis, that the whole ocean becomes Si(OH)4 poor during cooling periods, is suggested by low opal MAR in cores from both equatorial and Antarctic regions, perhaps as a result of low river input. terminations in this scenario would result from blooms of coccolithophorids triggered by low Si(OH)4 concentrations.

  3. Significance of atmospheric inputs of calcium over the southwestern Mediterranean region: High mountain lakes as tools for detection

    Microsoft Academic Search

    Elvira Pulido-Villena; Isabel Reche; Rafael Morales-Baquero

    2006-01-01

    We quantified dry and wet atmospheric deposition of calcium over the southwest Mediterranean region and we assessed its impact on calcium dynamics of two high mountain lakes differing in morphometry and catchment characteristics. Atmospheric deposition of Ca averaged 40 mmol m?2 yr?1, and it showed a seasonal pattern similar to that reported for Saharan dust export to the Mediterranean region,

  4. Significance of atmospheric inputs of calcium over the southwestern Mediterranean region: High mountain lakes as tools for detection

    Microsoft Academic Search

    Elvira Pulido-Villena; Isabel Reche; Rafael Morales-Baquero

    2006-01-01

    We quantified dry and wet atmospheric deposition of calcium over the southwest Mediterranean region and we assessed its impact on calcium dynamics of two high mountain lakes differing in morphometry and catchment characteristics. Atmospheric deposition of Ca averaged 40 mmol m-2 yr-1, and it showed a seasonal pattern similar to that reported for Saharan dust export to the Mediterranean region,

  5. The calculated influence of atmospheric conditions on solar cell ISC under direct and global solar irradiances

    NASA Technical Reports Server (NTRS)

    Mueller, Robert L.

    1987-01-01

    Calculations of the influence of atmospheric conditions on solar cell short-circuit current (Isc) are made using a recently developed computer model for solar spectral irradiance distribution. The results isolate the dependence of Isc on changes in the spectral irradiance distribution without the direct influence of the total irradiance level. The calculated direct normal irradiance and percent diffuse irradiance are given as a reference to indicate the expected irradiance levels. This method can be applied to the calibration of photovoltaic reference cells. Graphic examples are provided for amorphous silicon and monocrystalline silicon solar cells under direct normal and global normal solar irradiances.

  6. Influence of impurities on the uniform atmospheric-pressure discharge in helium

    SciTech Connect

    Wang Yanhui; Wang Dezhen [State Key Laboratory of Materials Modification by Laser, Electron, and Ion Beams, Department of Physics, Dalian University of Technology, Dalian 116024 (China)

    2005-02-01

    The influence of small nitrogen impurities on the uniform barrier discharge at atmospheric pressure in helium is investigated by numerical simulation with a one-dimensional fluid model. The simulation results show that in different discharge modes the influence of impurities is completely different. For glow discharge, small impurities result in the breakdown voltage dropping and thus cause the decrease in charged particle densities and discharge current density. In the case of Townsend discharge, nitrogen impurities can lead to the increase of charged particle densities and discharge current density, and even the change of discharge mode, but do not have a distinct impact on the breakdown voltage.

  7. The calculated influence of atmospheric conditions on solar cell ISC under direct and global solar irradiances

    NASA Astrophysics Data System (ADS)

    Mueller, Robert L.

    Calculations of the influence of atmospheric conditions on solar cell short-circuit current (Isc) are made using a recently developed computer model for solar spectral irradiance distribution. The results isolate the dependence of Isc on changes in the spectral irradiance distribution without the direct influence of the total irradiance level. The calculated direct normal irradiance and percent diffuse irradiance are given as a reference to indicate the expected irradiance levels. This method can be applied to the calibration of photovoltaic reference cells. Graphic examples are provided for amorphous silicon and monocrystalline silicon solar cells under direct normal and global normal solar irradiances.

  8. Atmosphere

    NSDL National Science Digital Library

    University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

    2003-01-01

    What is this atmosphere that surrounds the Earth? This instructional tutorial, part of an interactive laboratory series for grades 8-12, introduces students to the structure, effects, and components of the atmosphere. Here students investigate the composition of the atmosphere; effects of temperature, pressure, and ozone; the greenhouse effect; and how Earth compares with other planets. Interactive activities present students with opportunities to explore ideas and answer questions about the atmosphere, including its structure, the making of ozone, rocket launching, and measuring the atmosphere. Pop-up boxes provide additional information on topics such as dust, rain, and atmospheric composition. Students complete a final written review of six questions about the atmosphere. Copyright 2005 Eisenhower National Clearinghouse

  9. Human and natural influences on the changing thermal structure of the atmosphere

    PubMed Central

    Santer, Benjamin D.; Painter, Jeffrey F.; Bonfils, Céline; Mears, Carl A.; Solomon, Susan; Wigley, Tom M. L.; Gleckler, Peter J.; Schmidt, Gavin A.; Doutriaux, Charles; Gillett, Nathan P.; Taylor, Karl E.; Thorne, Peter W.; Wentz, Frank J.

    2013-01-01

    Since the late 1970s, satellite-based instruments have monitored global changes in atmospheric temperature. These measurements reveal multidecadal tropospheric warming and stratospheric cooling, punctuated by short-term volcanic signals of reverse sign. Similar long- and short-term temperature signals occur in model simulations driven by human-caused changes in atmospheric composition and natural variations in volcanic aerosols. Most previous comparisons of modeled and observed atmospheric temperature changes have used results from individual models and individual observational records. In contrast, we rely on a large multimodel archive and multiple observational datasets. We show that a human-caused latitude/altitude pattern of atmospheric temperature change can be identified with high statistical confidence in satellite data. Results are robust to current uncertainties in models and observations. Virtually all previous research in this area has attempted to discriminate an anthropogenic signal from internal variability. Here, we present evidence that a human-caused signal can also be identified relative to the larger “total” natural variability arising from sources internal to the climate system, solar irradiance changes, and volcanic forcing. Consistent signal identification occurs because both internal and total natural variability (as simulated by state-of-the-art models) cannot produce sustained global-scale tropospheric warming and stratospheric cooling. Our results provide clear evidence for a discernible human influence on the thermal structure of the atmosphere. PMID:24043789

  10. Coupled ocean-atmosphere surface variability and its climate impacts in the tropical Atlantic region

    Microsoft Academic Search

    B. Fontaine; Serge Janicot; P. Roucou

    1999-01-01

    This study examines time evolution and statistical relationships involving the two leading ocean-atmosphere coupled modes\\u000a of variability in the tropical Atlantic and some climate anomalies over the tropical 120?°W–60?°W region using selected historical\\u000a files (75-y near global SSTs and precipitation over land), more recent observed data (30-y SST and pseudo wind stress in the\\u000a tropical Atlantic) and reanalyses from the

  11. Harvard Forest regional-scale air mass composition by Patterns in Atmospheric Transport History (PATH)

    Microsoft Academic Search

    J. L. Moody; J. W. Munger; A. H. Goldstein; D. J. Jacob; S. C. Wofsy

    1998-01-01

    We calculated 4 years (1990-1993) of back trajectories arriving at Harvard Forest and used them to define patterns in atmospheric transport history. This information was used to assess the degree to which regional-scale transport modulates the chemical composition of air masses sampled at Harvard Forest. Different seasonal signals in trace-gas concentration are derived for different flow patterns. Throughout the year,

  12. Earth’s Interaction Region: Plasma-Neutral Interactions in the Weakly Ionized gas of Earth’s High Latitude Upper Atmosphere

    NASA Astrophysics Data System (ADS)

    Thayer, Jeffrey; Hsu, Vicki

    2015-04-01

    The high-latitude regions of Earth’s upper atmosphere are strongly influenced by plasma-neutral interactions. These interactions couple electrodynamic processes of the ionosphere with hydrodynamic processes of the more abundant thermosphere neutral gas, consequently connecting the high-latitude upper atmosphere to distant regions of the geoplasma environment. This produces a complex spatial and temporal interplay of competing processes that results in a myriad of physical and chemical responses and a rich array of neutral and plasma morphologies that constitute the high-latitude thermosphere and ionosphere. The altitude extent from the lower thermosphere to the upper ionosphere (90km – 1000km) can be considered Earth’s space-atmosphere interaction region - likened to the solar chromosphere’s interaction region where radiative processes and hydrodynamic waves from the dense lower atmosphere produce a cold lower boundary that quickly transitions over a few 100 kilometers to neutral and plasma temperatures that are five times hotter. A thousand or more kilometers further in altitude, Earth's upper atmosphere becomes a hot, collisionless, geomagnetically controlled protonosphere whose neutral and plasma population originates from the thermosphere and ionosphere. A grand challenge in the study of Earth’s interaction region is how the collision-dominated thermosphere/ionosphere system exchanges energy, mass and momentum with the collisionless magnetosphere. This talk will focus primarily on collision-dominated processes of the high-latitude ionosphere and the electromagnetic energy transfer processes that lead to frictional heating of ions and neutrals, and plasma instability phenomenon that leads to extreme electron heating. Observations of the ionosphere response to these processes will be illustrated using incoherent scatter radar measurements. Relevance to the solar chromosphere will be identified where appropriate and outstanding issues in Earth’s interaction region will be discussed.

  13. Using regional-scale atmospheric ?13C of CO2 as an indicator of ecosystem health and function

    NASA Astrophysics Data System (ADS)

    Alden, C. B.; Miller, J. B.; White, J. W.; Yadav, V.; Michalak, A. M.

    2012-12-01

    Year to year terrestrial CO2 uptake and release is highly variable and is a result of, among other factors, weather and climate variability. One of the key ecosystem parameters that links surface-atmosphere fluxes of energy, water and carbon is stomatal conductance. By measuring and analyzing atmospheric patterns of CO2 and its 13C content over North America, we can begin to identify regional scale changes in stomatal conductance, because conductance is closely related to plant isotopic discrimination. Furthermore, 13C is a useful tracer of the differential responses of C3 and C4 plants to climate and weather anomalies, because C3 and C4 plants have very different isotopic discrimination. Both aspects of the terrestrial carbon cycle are of great interest to those seeking to understand the potential effects of global climate change on cropland and forest productivity, natural CO2 sinks, continental runoff, and continental water and energy exchange with the atmosphere. Our findings may be particularly important for parameterization of process-based models, in light of recent results suggesting that stomatal conductance models driven by vapor pressure deficit (Leuning Model) better predict atmospheric ?13C than do models driven by relative humidity (Ball-Berry Model). For the first time, spatial and temporal density of ?13C of CO2 atmospheric observations may be high enough to allow for regional inversions of ?13CO2 to optimize prior estimates of plant discrimination (and disequilibrium flux -- an isoflux resulting from the combination of a finite residence time of carbon in terrestrial biosphere pools and a changing atmospheric signature due to human burning of fossil fuels with a plant-derived ?13C signature). We perform a Bayesian synthesis inversion for 1) CO2 fluxes and 2) ?13CO2 isofluxes, over the North American region: 145-25°W longitude and 10-80°N latitude. Inversion resolution, in order to avoid aggregation errors, is 1°x1° and 3-hourly, but optimized fluxes are interpreted at monthly and regional (~106 km2) scales. Influence functions (footprints) are generated with FLEXPART, driven by National Centers for Environmental Prediction Global Forecast System meteorology. Prior information is from CarbonTracker 2011 and SiB, and background CO2 and ?13C values are from NOAA/ESRL marine boundary layer and aircraft data. Quasi-daily atmospheric observations are from NOAA/ESRL Global Monitoring Division tall towers in Park Falls, Wisconsin; Argyle, Maine; Moody, Texas; West Branch, Iowa; and Beech Island, South Carolina. Weekly observations are from Environment Canada tall towers in Estevan Point, British Columbia; Sable Island, Nova Scotia; Fraserdale, Ontario; Churchill, Manitoba; and East Trout Lake, Saskatchewan. We will present optimized, monthly spatial fields of 13C plant discrimination for North America. By comparing these posterior results to the SiB prior, we will begin to evaluate potential shortcomings in SiB with regard to both C3/C4 distribution and conductance.

  14. Regional and global impacts of Criegee intermediates on atmospheric sulphuric acid concentrations and first steps of aerosol formation.

    PubMed

    Percival, Carl J; Welz, Oliver; Eskola, Arkke J; Savee, John D; Osborn, David L; Topping, David O; Lowe, Douglas; Utembe, Steven R; Bacak, Asan; McFiggans, Gordon; Cooke, Michael C; Xiao, Ping; Archibald, Alexander T; Jenkin, Michael E; Derwent, Richard G; Riipinen, Ilona; Mok, Daniel W K; Lee, Edmond P F; Dyke, John M; Taatjes, Craig A; Shallcross, Dudley E

    2013-01-01

    Carbonyl oxides ("Criegee intermediates"), formed in the ozonolysis of alkenes, are key species in tropospheric oxidation of organic molecules and their decomposition provides a non-photolytic source of OH in the atmosphere (Johnson and Marston, Chem. Soc. Rev., 2008, 37, 699, Harrison et al, Sci, Total Environ., 2006, 360, 5, Gäb et al., Nature, 1985, 316, 535, ref. 1-3). Recently it was shown that small Criegee intermediates, C.I.'s, react far more rapidly with SO2 than typically represented in tropospheric models, (Welz, Science, 2012, 335, 204, ref. 4) which suggested that carbonyl oxides could have a substantial influence on the atmospheric oxidation of SO2. Oxidation of 502 is the main atmospheric source of sulphuric acid (H2SO4), which is a critical contributor to aerosol formation, although questions remain about the fundamental nucleation mechanism (Sipilä et al., Science, 2010, 327, 1243, Metzger et al., Proc. Natl. Acad. Sci. U. S. A., 2010 107, 6646, Kirkby et al., Nature, 2011, 476, 429, ref. 5-7). Non-absorbing atmospheric aerosols, by scattering incoming solar radiation and acting as cloud condensation nuclei, have a cooling effect on climate (Intergovernmental Panel on Climate Change (IPCC), Climate Change 2007: The Physical Science Basis, Cambridge University Press, 2007, ref. 8). Here we explore the effect of the Criegees on atmospheric chemistry, and demonstrate that ozonolysis of alkenes via the reaction of Criegee intermediates potentially has a large impact on atmospheric sulphuric acid concentrations and consequently the first steps in aerosol production. Reactions of Criegee intermediates with SO2 will compete with and in places dominate over the reaction of OH with SO2 (the only other known gas-phase source of H2SO4) in many areas of the Earth's surface. In the case that the products of Criegee intermediate reactions predominantly result in H2SO4 formation, modelled particle nucleation rates can be substantially increased by the improved experimentally obtained estimates of the rate coefficients of Criegee intermediate reactions. Using both regional and global scale modelling, we show that this enhancement is likely to be highly variable spatially with local hot-spots in e.g. urban outflows. This conclusion is however contingent on a number of remaining uncertainties in Criegee intermediate chemistry. PMID:24600996

  15. Influence of equatorial diatom processes on Si deposition and atmospheric CO2 cycles at glacial//interglacial timescales

    E-print Network

    Maine, University of

    Influence of equatorial diatom processes on Si deposition and atmospheric CO2 cycles at glacial diatom processes on Si deposition and atmospheric CO2 cycles at glacial/interglacial timescales, Paleoceanography, 19, PA3011, doi:10.1029/2003PA000929. 1. Introduction [2] CO2 increased before the melting

  16. Background levels of atmospheric mercury in Kagoshima City, and influence of mercury emission from Sakurajima Volcano, Southern Kyushu, Japan

    Microsoft Academic Search

    Takashi Tomiyasu; Ayako Nagano; Hayao Sakamoto; Norinobu Yonehara

    2000-01-01

    Vapor phase mercury concentration was determined daily for 1 year (Jan. 1996–Jan. 1997) in order to present the levels of atmospheric mercury in Kagoshima City and to estimate the influence of mercury emission from Sakurajima Volcano, southern Kyushu, Japan. The atmospheric mercury was collected on a porous gold collector at Kagoshima University and was determined by cold vapor atomic absorption

  17. The Atmospheric Bridge: The Influence of ENSO Teleconnections on Air-Sea Interaction over the Global Oceans

    Microsoft Academic Search

    Michael A. Alexander; Ileana Bladé; Matthew Newman; John R. Lanzante; Ngar-Cheung Lau; James D. Scott

    2002-01-01

    During El Niño-Southern Oscillation (ENSO) events, the atmospheric response to sea surface temperature (SST) anomalies in the equatorial Pacific influences ocean conditions over the remainder of the globe. This connection between ocean basins via the `atmospheric bridge' is reviewed through an examination of previous work augmented by analyses of 50 years of data from the National Centers for Environmental Prediction-National

  18. Influence of Benzene on Aerosol- and Gas-Phase Chemistry in Haze Analog Atmospheres

    NASA Astrophysics Data System (ADS)

    Yoon, Y. H.; Horst, S. M.; Li, R.; Barth, E. L.; Trainer, M. G.; De Gouw, J. A.; Tolbert, M. A.

    2012-12-01

    Benzene (C6H6) has been observed in the haze atmospheres of Saturn and Jupiter by the Infrared Space Observatory [1] and in the atmosphere of Titan, most recently during the Cassini mission by the Ion and Neutral Mass Spectrometer [2,3] and the Composite Infrared Spectrometer [4]. Photochemical reactions involving benzene may influence polycyclic aromatic hydrocarbon formation, aerosol formation, and the radiative balance of planetary atmospheres. We measure the influence of benzene on a model system, Titan analog particles, in the laboratory by photolyzing CH4/N2 gas mixtures infused with ppm-levels of C6H6 using a deuterium lamp (115-400 nm). We measure the chemical composition of the aerosol-phase products and gas-phase products using aerosol mass spectrometry and proton-transfer ion-trap mass spectrometry, respectively. We measure the optical properties of the aerosol-phase products at 532 nm using cavity ring-down aerosol extinction spectroscopy. These studies are compared to previous studies [5,6] of Titan analog particles formed by methane photolysis. [1] Bezard B. et al. (2001) Icarus, 154, 492-500. [2] Waite, J. H. et al. (2007) Science, 316, 870-875. [3] Vuitton, V. et al. (2008) JGR, 113, E05007. [4] Coustenis, A. et al. (2007) Icarus, 189, 35-62. [5] Hasenkopf, C.A. et al. (2010) Icarus, 207, 903-913. [6] Trainer, M. G. et al. (2012) Astrobiology, 12, 315-326.

  19. Regional and Local Carbon Flux Information from a Continuous Atmospheric CO2 Network in the Rocky Mountains

    NASA Astrophysics Data System (ADS)

    Heck, S. L.; Stephens, B.; Watt, A.

    2007-12-01

    We will present preliminary carbon flux estimates from the Regional Atmospheric Continuous CO2 Network in the Rocky Mountains (Rocky RACCOON). In order to improve our understanding of regional carbon fluxes in the Rocky Mountain West, we have developed and deployed autonomous, inexpensive, and robust CO2 analyzers (AIRCOA) at five sites throughout Colorado and Utah, and plan additional deployments on the Navajo Reservation, Arizona in September 2007 and atop Mount Kenya, Africa in November 2007. We have used a one- dimensional CO2 budget equation, following Bakwin et al. (2004), to estimate regional monthly-mean fluxes from our continuous CO2 concentrations. These comparisons between our measurements and estimates of free- tropospheric background concentrations reveal regional-scale CO2 flux signals that are generally consistent with one another across the Rocky RACCOON sites. We will compare the timing and magnitude of these estimates with expectations from local-scale eddy-correlation flux measurements and bottom-up ecosystem models. We will also interpret the differences in monthly-mean flux signals between our sites in terms of their varying upwind areas of influence and inferred regional variations in CO2 fluxes. Our measurements will be included in future CarbonTracker assimilation runs and other planned model-data fusion efforts. However, questions still exist concerning the ability of these models to accurately represent the various influences on CO2 concentrations in continental boundary layers, and at mountaintop sites in particular. We will present an analysis of the diurnal cycles in CO2 concentration and CO2 variability at our sites, and compare these to various model estimates. Several of our sites near major population centers reflect the influence of industrial CO2 sources in afternoon upslope flows, with CO2 concentration increasing and variable in the mid to late afternoon. Other more remote sites show more consistent and decreasing CO2 concentrations throughout the afternoon. These measurements provide insight as to when and under what conditions mountaintop CO2 signals are regionally representative, as well as first-order constraints on boundary-layer heights and flux rates for use in evaluating model fidelity. Because of coarse representation of topography and boundary-layer mixing biases, forward model CO2 diurnal cycles can be 180 degrees out of phase with respect to assimilated mountaintop CO2 observations if care is not taken in the choice of model level used.

  20. Atmospheric constraints on Plant Water Use Efficiency - drivers and regional patterns of change since 1900

    NASA Astrophysics Data System (ADS)

    Groenendijk, M.; Cox, P.; Lambert, F. H.; Booth, B.; Huntingford, C.

    2013-12-01

    Water Use Efficiency (WUE) defines the relationship between land-atmosphere water and carbon fluxes. With this simple mechanism, hydrological and carbon-cycle responses of vegetation to climate change can be more easily quantified. WUE increases with atmospheric carbon dioxide (CO2) concentration but also depends on changes in humidity and temperature. A positive CO2 fertilization effect can be locally constrained by humidity and temperature. By combining observed trends of these three climate variables over the 20th century regional trends in WUE can be calculated. The ecosystem WUEe is defined as a ratio of gross primary production and transpiration fluxes. On the leaf scale this is equal to the atmospheric WUEa, which is a function of the ambient and internal CO2 concentration, the saturated specific humidity (a function of temperature) and relative humidity. Using Fluxnet and CRU TS3.2 observations, and the JULES and HadCM3 models we explore the temporal and spatial variation of WUEe and WUEa, and how they respond to climate change. Leaf level definitions are valid at site level, where WUEe and WUEa simulated with JULES are equal and linearly increasing with atmospheric CO2 concentration for a range of sites. For drier sites lower values of both were simulated. The simulated values are within the same range as values derived from eddy covariance observations. Having shown the near equivalence between WUEe and WUEa for specific sites, we can use the formula for WUEa to estimate the change in global plant WUE over the 20th century, using observed climatological data and CO2 concentrations. The global average WUE increased by 25% since 1900, closely following the atmospheric CO2 concentration. But we identify large regional variation, with regions where WUE increased, but some significant regions where WUE has actually decreased during the last century. Here the CO2 fertilization effect is overtaken by an increasing offsetting temperature and related saturated specific humidity effect. In the future these drier regions will not only have to cope with a decreasing water availability but also with the related decrease in WUE, amplifying a decreasing plant carbon uptake, and if occurring in areas of agriculture, then reducing crop yield.

  1. Titan's atmospheric and surface properties of the Ontario Lacus region from Cassini/VIMS remote sensing

    NASA Astrophysics Data System (ADS)

    Negrão, A.; Adriani, A.; Moriconi, M.; Coradini, A.; D'Aversa, E.; Filacchione, G.; Lunine, J.

    2009-04-01

    The existence of oceans or lakes of liquid hydrocarbons on Titan's surface was predicted more than 20 years ago. These would serve as a source of atmospheric methane and would also contain the end products of the photochemical reactions occurring high in the atmosphere. Although no oceans were ever found, lake-like features poleward of 70°N were first detected by the radar instrument onboard Cassini on July 2006. Before that, Cassini Imaging Science Subsystem (ISS) images of the south pole from June 2005 revealed an intriguing lake-like dark feature named Ontario Lacus. Recently an interesting and important result has been published about the identification of liquid ethane contained within Ontario Lacus (Brown et al. 2008). The authors analysed a near-infrared Visual and Infrared Mapping Spectrometer (VIMS) observation of the Ontario Lacus performed the 2007 December 4, during the T38 flyby. Their result needs nevertheless to be confirmed and improved using a more detailed methodology. Here we report on the analysis of this observation using a radiative transfer model (the libRadtran package) to simulate the atmospheric contribution. LibRadtran is a library of tools developed for radiative transfer calculations in the Earth's atmosphere, but adapted here to Titan's atmospheric conditions. Extinction sources were calculated for atmospheric methane and aerosols as a function of altitude and wavelength. Using the DISORT solver we were able to invert the surface spectrum of the lake interior and of an adjacent, non-lake region, in the near-infrared methane windows. The surface spectra were then compared with spectra of different ices and liquid hydrocarbons, yielding constraints on the possible constituents of Titan's lakes and their adjacent areas. Reference: Brown, R. et al. 2008. The identification of liquid ethane in Titan's Ontario Lacus, Nature 454, 607-610.

  2. NO Detection by Pulsed Polarization of Lambda Probes–Influence of the Reference Atmosphere

    PubMed Central

    Fischer, Sabine; Schönauer-Kamin, Daniela; Pohle, Roland; Fleischer, Maximilian; Moos, Ralf

    2013-01-01

    The pulsed polarization measurement technique using conventional thimble type lambda probes is suitable for low ppm NOx detection in exhaust gas applications. To evaluate the underlying sensor mechanism, the unknown influence of the reference atmosphere on the NO sensing behavior is investigated in this study. Besides answering questions with respect to the underlying principle, this investigation can resolve the main question of whether a simplified sensor element without reference may be also suitable for NO sensing using the pulsed polarization measurement technique. With an adequate sensor setup, the reference atmosphere of the thimble type lambda probe is changed completely after a certain diffusion time. Thus, the sensor response regarding NO is compared with and without different gas atmospheres on both electrodes. It is shown that there is still a very good NO sensitivity even without reference air, although the NO response is reduced due to non-existing overlying mixed potential type voltage, which is otherwise caused by different atmospheres on both electrodes. Considering these results, we see an opportunity to simplify the standard NOx sensor design by omitting the reference electrode.

  3. THE INFLUENCE OF ATMOSPHERIC SCATTERING AND ABSORPTION ON OHMIC DISSIPATION IN HOT JUPITERS

    SciTech Connect

    Heng, Kevin [ETH Zuerich, Institute for Astronomy, Wolfgang-Pauli-Strasse 27, CH-8093 Zuerich (Switzerland)

    2012-03-20

    Using semi-analytical, one-dimensional models, we elucidate the influence of scattering and absorption on the degree of Ohmic dissipation in hot Jovian atmospheres. With the assumption of Saha equilibrium, the variation in temperature is the main driver of the variations in the electrical conductivity, induced current, and Ohmic power dissipated. Atmospheres possessing temperature inversions tend to dissipate most of the Ohmic power superficially, at high altitudes, whereas those without temperature inversions are capable of greater dissipation deeper down. Scattering in the optical range of wavelengths tends to cool the lower atmosphere, thus reducing the degree of dissipation at depth. Purely absorbing cloud decks (in the infrared), of a finite extent in height, allow for localized reductions in dissipation and may reverse a temperature inversion if they are dense and thick enough, thus greatly enhancing the dissipation at depth. If Ohmic dissipation is the mechanism for inflating hot Jupiters, then variations in the atmospheric opacity (which may be interpreted as arising from variations in metallicity and cloud/haze properties) and magnetic field strength naturally produce a scatter in the measured radii at a given strength of irradiation. Future work will determine if these effects are dominant over evolutionary effects, which also contribute a scatter to the measured radii.

  4. Multiyear measurements of the oceanic and atmospheric boundary layers at the Brazil-Malvinas confluence region

    NASA Astrophysics Data System (ADS)

    Pezzi, Luciano Ponzi; de Souza, Ronald Buss; Acevedo, OtáVio; Wainer, Ilana; Mata, Mauricio M.; Garcia, Carlos A. E.; de Camargo, Ricardo

    2009-10-01

    This study analyzes and discusses data taken from oceanic and atmospheric measurements performed simultaneously at the Brazil-Malvinas Confluence (BMC) region in the southwestern Atlantic Ocean. This area is one of the most dynamical frontal regions of the world ocean. Data were collected during four research cruises in the region once a year in consecutive years between 2004 and 2007. Very few studies have addressed the importance of studying the air-sea coupling at the BMC region. Lateral temperature gradients at the study region were as high as 0.3°C km-1 at the surface and subsurface. In the oceanic boundary layer, the vertical temperature gradient reached 0.08°C m-1 at 500 m depth. Our results show that the marine atmospheric boundary layer (MABL) at the BMC region is modulated by the strong sea surface temperature (SST) gradients present at the sea surface. The mean MABL structure is thicker over the warmside of the BMC where Brazil Current (BC) waters predominate. The opposite occurs over the coldside of the confluence where waters from the Malvinas (Falkland) Current (MC) are found. The warmside of the confluence presented systematically higher MABL top height compared to the coldside. This type of modulation at the synoptic scale is consistent to what happens in other frontal regions of the world ocean, where the MABL adjusts itself to modifications along the SST gradients. Over warm waters at the BMC region, the MABL static instability and turbulence were increased while winds at the lower portion of the MABL were strong. Over the coldside of the BC/MC front an opposite behavior is found: the MABL is thinner and more stable. Our results suggest that the sea-level pressure (SLP) was also modulated locally, together with static stability vertical mixing mechanism, by the surface condition during all cruises. SST gradients at the BMC region modulate the synoptic atmospheric pressure gradient. Postfrontal and prefrontal conditions produce opposite thermal advections in the MABL that lead to different pressure intensification patterns across the confluence.

  5. Regional Sea Level Variations from GRACE, InSAR and a Regional Atmospheric Climate Model Output Products

    NASA Astrophysics Data System (ADS)

    Hsu, C. W.; Velicogna, I.; Rignot, E. J.; Wahr, J. M.

    2014-12-01

    We generate static regional sea level variations (sea level fingerprints, SLF) from ice sheets, glaciers and land hydrology using 10 years of monthly NASA/DLR GRACE satellite data and 40 years of ice sheet mass balance from the mass budget method (surface mass balance from a regional atmospheric climate model minus ice discharge along the periphery). We evaluate the impact of the spatial distribution in ice sheet mass balance on the inferred regional sea level pattern. Based on the results, we derive requirements on the spatial scale of mass loss needed to resolve the regional pattern of sea level change. In the calculation of the water and ice mass changes over land, we also need to restore the amplitude of the GRACE signal before calculating the regional sea level pattern. Here, we describe an improved scaling factor method that comprises both a seasonal and a long-term component. We discuss the impact of these components on the retrieved regional sea level pattern. Using the SLF, we identify the sources of observed sea level variations. We show that the cumulative SLF describe a large portion of the trend and annual amplitude of the observed sea level variations at both the global and basin scales. When comparing the cumulative SLF with observations of sea level change from steric corrected altimetry, we find an excellent agreement at the global and basin scales. We discuss differences in sea level pattern between the last decade and the prior 40 years. This work was conducted at the University of California Irvine and at Caltech's Jet Propulsion Laboratory under a contract with the National Aeronautics and Space Administration.

  6. Complex topography influences atmospheric nitrate deposition in a neotropical mountain rainforest

    NASA Astrophysics Data System (ADS)

    Makowski Giannoni, Sandro; Rollenbeck, Rütger; Fabian, Peter; Bendix, Jörg

    2013-11-01

    Future increase of atmospheric nitrogen deposition in tropical regions is expected to have negative impacts on forests ecosystems and related biogeochemical processes. In tropical mountain forests topography causes complex streamflow and rainfall patterns, governing the atmospheric transport of pollutants and the intensity and spatial variability of deposition. The main goal of the current study is to link spatio-temporal patterns of upwind nitrogen emissions and nitrate deposition in the San Francisco Valley (eastern Andes of southern Ecuador) at different altitudinal levels. The work is based on Scanning Imaging Absorption SpectroMeter for Atmospheric CHartographY (SCIAMACHY) retrieved-NO2 concentrations, NOx biomass burning emissions from the Global Fire Emissions Database (GFEDv3), and regional vehicle emissions inventory (SA-INV) for urban emissions in South America. The emission data is used as input for lagrangian atmospheric backward trajectory modeling (FLEXTRA) to model the transport to the study area. The results show that NO concentrations in occult precipitation samples are significantly correlated to long-range atmospheric secondary nitrogen transport at the highest meteorological stations (MSs) only, whereas for NO concentrations in rain samples this correlation is more pronounced at the lower MSs. We conclude that ion concentrations in occult precipitation at the uppermost MSs are mainly linked to distant emission sources via the synoptic circulation impinging the more exposed higher sites. Lower correlations close to the valley bottom are due to a lower occult precipitation frequency and point to a contamination of the samples by local pollution sources not captured by the used emission data sources.

  7. Atmospheric Profiling using GPS Radio Occultation over the Australian and Antarctic regions

    NASA Astrophysics Data System (ADS)

    Norman, R.; Le Marshall, J.; Carter, B. A.; Kirchengast, G.; Alexander, S.; Wang, C. S.; Zhang, K.

    2014-12-01

    The space-based Global Positioning System (GPS) Radio Occultation (RO) technique is ideal for sounding the Earth's atmosphere. The GPS RO technique uses GPS receiver's on-board Low Earth Orbit (LEO) satellites to measure the received radio signals from GPS satellites. Atmospheric parameter profiles of electron density, temperature, pressure and water vapor can then be obtained using well defined and robust retrieval processes. In this study atmospheric parameter profiles were retrieved from Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) GPS RO measurements for the years 2007 to 2013 over Australia, Antarctica and their surrounding oceans. The yearly and bi-monthly tropopause height and temperature and climatic trends are investigated and co-located GPS RO and radiosonde atmospheric profiles are compared. Forecast skill scores with and without GPS RO data over the Australian and Antarctic regions are also assessed. Finally, a 3-D ray tracing technique was developed to investigate and improve the GPS RO technique. Simulated results from a tropospheric storm event on GPS RO signal propagation are investigated.

  8. Influence of Atmospheric Oxygen on Heavy Metal Mobility in Sediment and Soil (7 pp)

    Microsoft Academic Search

    Katharina Zehl; Jürgen W. Einax

    2005-01-01

    Thuringia (Germany). The cadmium contamination is estimated in the plant region by using geostatistical methods, in this case kriging estimation. In consideration of the overestimation of Cd mobility and implementation of a mobility correction fac- tor, the real Cd mobility is calculated for this area. The polluted area decreases down to 49% compared to the original one. Outlook. The influence

  9. The importance of atmospheric ammonia in the Rocky Mountain region of the western U.S

    NASA Astrophysics Data System (ADS)

    Collett, J. L.; Benedict, K. B.; Chen, D.; Day, D.; Prenni, A. J.; Li, Y.; Kreidenweis, S. M.; Schichtel, B. A.; McDade, C.; Malm, W. C.

    2013-12-01

    Although it is not a regulated pollutant, ammonia is an important contributor to several air quality problems. Included among these are the formation of fine particles that contribute to visibility degradation and adverse health effects as well as contributions to excess nitrogen deposition to sensitive ecosystems. Because it is not regulated, gaseous ammonia and fine particle ammonium have traditionally not been routinely measured in many air quality monitoring networks. Measurements of ammonium wet deposition by the National Atmospheric Deposition Program, however, clearly indicate an increasing contribution to reactive nitrogen deposition. Here we report observations of several recent research efforts to characterize atmospheric ammonia and ammonium in the Rocky Mountain region of the western United States. These include measurements made as part of the Rocky Mountain Atmospheric Nitrogen and Sulfur (RoMANS) deposition study (2006-10), the Grand Teton Reactive Nitrogen Deposition Study (GrandTReNDS) (2011), and through pilot-scale operation of an NHx (NHx = gaseous NH3 plus fine particle NH4+) monitoring effort at 9 sites within the Interagency Monitoring of PROtected Visual Environments (IMPROVE) program (2011-12). Measurements during RoMANS clearly reveal the importance of agricultural source emission contributions to both dry and wet reactive nitrogen deposition in Rocky Mountain National Park. The importance of ammonia and ammonium deposition is even greater at Grand Teton National Park, which often sits downwind of extensive agricultural operations in central Idaho and northern Utah. Over a year of measurements in the IMPROVE NHx pilot network reveals strong spatial gradients in reduced nitrogen concentrations across the Rocky Mountain region, with higher concentrations in regions closer to agricultural sources and at locations and times strongly impacted by wildfires. These observations, along with additional observations from other related studies in the region, will be discussed.

  10. The influence of land-atmosphere interactions on variability of the North American Monsoon

    NASA Technical Reports Server (NTRS)

    Small, Eric; Lakshmi, Venkat

    2005-01-01

    Our project focused on the influence of land-atmosphere interactions on variability of North American Monsoon System (NAMS) precipitation is summarized in seven published manuscripts (listed below). Three of these manuscripts (Matsui et al. 2003; Matsui et al. 2005; Small and Kurc 2003) were completed solely with support from this NASA project. The remaining four were completed with additional support from NOAA. Our primary results are summarized: 1) Test of Rocky Mountains snowcover-NAMS rainfall hypothesis. Testing radiation and convective precipitation parameterization in MM5. Analysis of soil moisture-radiation feedbacks in semiarid environments from field observations and modeling.

  11. An overview of the regional experiments for land-atmosphere exchanges 2012 (REFLEX 2012) campaign

    NASA Astrophysics Data System (ADS)

    Timmermans, Wim; Van der Tol, Christiaan; Timmermans, Joris; Ucer, Murat; Chen, Xuelong; Alonso, Luis; Moreno, Jose; Carrara, Arnaud; Lopez, Ramon; de la Cruz Tercero, Fernando; Corcoles, Horacio L.; de Miguel, Eduardo; Sanchez, Jose A. G.; Pérez, Irene; Franch, Belen; Munoz, Juan-Carlos J.; Skokovic, Drazen; Sobrino, Jose; Soria, Guillem; MacArthur, Alasdair; Vescovo, Loris; Reusen, Ils; Andreu, Ana; Burkart, Andreas; Cilia, Chiara; Contreras, Sergio; Corbari, Chiara; Calleja, Javier F.; Guzinski, Radoslaw; Hellmann, Christine; Herrmann, Ittai; Kerr, Gregoire; Lazar, Adina-Laura; Leutner, Benjamin; Mendiguren, Gorka; Nasilowska, Sylwia; Nieto, Hector; Pachego-Labrador, Javier; Pulanekar, Survana; Raj, Rahul; Schikling, Anke; Siegmann, Bastian; von Bueren, Stefanie; Su, Zhongbo (Bob)

    2014-12-01

    The REFLEX 2012 campaign was initiated as part of a training course on the organization of an airborne campaign to support advancement of the understanding of land-atmosphere interaction processes. This article describes the campaign, its objectives and observations, remote as well as in situ. The observations took place at the experimental Las Tiesas farm in an agricultural area in the south of Spain. During the period of ten days, measurements were made to capture the main processes controlling the local and regional land-atmosphere exchanges. Apart from multi-temporal, multi-directional and multi-spatial space-borne and airborne observations, measurements of the local meteorology, energy fluxes, soil temperature profiles, soil moisture profiles, surface temperature, canopy structure as well as leaf-level measurements were carried out. Additional thermo-dynamical monitoring took place at selected sites. After presenting the different types of measurements, some examples are given to illustrate the potential of the observations made.

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

    SciTech Connect

    Agúndez, Marcelino; Selsis, Franck [Univ. Bordeaux, LAB, UMR 5804, F-33270 Floirac (France); Venot, Olivia [Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Iro, Nicolas, E-mail: Marcelino.Agundez@obs.u-bordeaux1.fr [Theoretical Meteorology group, Klimacampus, University of Hamburg, Grindelberg 5, D-20144 Hamburg (Germany)

    2014-02-01

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

  13. Large-scale atmospheric influence on the physical and biogeochemical properties of the Benguela upwelling system

    NASA Astrophysics Data System (ADS)

    Tim, Nele; Zorita, Eduardo; Hünicke, Birgit

    2014-05-01

    The Namibian upwelling region is one of the four Eastern Boundary Upwelling Ecosystems and among the most productive areas in the World Ocean. Here, upwelling indices have been defined in three ways. First, by performing EOF analyses of Sea Surface Temperature (SST) observations HadlSST1 and high resolution ocean model simulations (MPI-OM (STORM) and MOM4), driven by meteorological reanalysis. Second, water vertical velocity of STORM and MOM4. Third, the area between the 13°C isotherm and the coastline was used to indicate the intensity of the upwelling. Correlations with observed atmospheric variables (NCEP reanalysis) over the whole southern Atlantic show which conditions favour upwelling: higher than normal South Atlantic anticyclone, strong and southerly wind/wind stress and pressure and air temperature contrast between ocean and land. Separating the coastal area off southern Africa at Lüderitz (28°S) depicts the differences between the northern and southern Benguela upwelling region. Northern Benguela is characterised by a negative trend in upwelling over the last 60 year, Southern Benguela by a positive one. Furthermore, Northern Benguela upwelling seems to be influenced strongly by the conditions described above while the wind field correlated with the upwelling south of 28°S do not show stronger southerly winds. Additionally, the southern upwelling index of MOM4 is not reflected properly in the corresponding SST field. A reason for this could be an overlaying signal, possibly the advection of warm air from the Indian or the central Atlantic Ocean. The sea level pressure (SLP) gradient between land and ocean of NCEP reanalysis provide a opposite trend to the one postulated by Bakun (¹). We did not find an indication for a stronger pressure contrast between land and ocean. Correlations with indices of El Niño Southern Oscillation (ENSO), the Antarctic Oscillation (AAO) and an index of the tropical Atlantic SST variability. None of these correlations is strong enough to claim a detection of a main driver of upwelling. However, a significant relationship between the summer upwelling and ENSO can be found. The SST-based index is also significantly correlated with the tropical Atlantic. In contrast, the upwelling indices of the vertical velocities show significant correlations with the AAO. Spectral analysis of the vertical velocity index (STORM) shows especially in summer a clear peak at timescales of 5 years. The longer series of HadlSST1 additionally displays decadal variability. The oxygen minimum zone in the Benguela region has an important impact on the ecosystem and local fisheries. The content of South Atlantic Central Water (SACW) on the shelf drives the intensity and extension of the oxygen minimum zone. Therefore, the water masses with the STORM and MOM4 simulations have been analysed. The STORM simulation does not contain biogeochemistry and the MOM4 simulation is too short. Thus, the analysis of the water masses, their origin and pathways through the South Atlantic will be analysed with a longer MOM simulation and the MPI run of the Climate Model Intercomparison project 5. (¹) Bakun, A. (1990). Global climate change and intensification of coastal ocean upwelling. Science, 247:198-201.

  14. Greenhouse gas emissions derived from regional measurement networks and atmospheric inversions: Results from the MCI and INFLUX experiments

    Microsoft Academic Search

    K. J. Davis; A. E. Andrews; M. Cambaliza; A. Denning; K. R. Gurney; T. Lauvaux; N. L. Miles; S. M. Ogle; A. Possolo; S. Richardson; A. E. Schuh; P. B. Shepson; C. Sweeney; J. C. Turnbull; T. O. West; J. R. Whetstone

    2010-01-01

    Atmospheric evaluation of emissions inventories is increasingly envisioned as a critical element of greenhouse gas emissions regulation. Atmospheric inversions utilizing dense regional networks of greenhouse gas measurements, however, are scarce. Discussions of the measurements and methods required to infer fluxes at spatial and temporal resolutions sufficient to meet the needs of policy makers, therefore, remain largely hypothetical. We present results

  15. The influence of Indian Ocean atmospheric circulation on Warm Pool hydroclimate during the Holocene epoch

    NASA Astrophysics Data System (ADS)

    Tierney, J. E.; Oppo, D. W.; Legrande, A. N.; Huang, Y.; Rosenthal, Y.; Linsley, B. K.

    2012-10-01

    Existing paleoclimate data suggest a complex evolution of hydroclimate within the Indo-Pacific Warm Pool (IPWP) during the Holocene epoch. Here we introduce a new leaf wax isotope record from Sulawesi, Indonesia and compare proxy water isotope data with ocean-atmosphere general circulation model (OAGCM) simulations to identify mechanisms influencing Holocene IPWP hydroclimate. Modeling simulations suggest that orbital forcing causes heterogenous changes in precipitation across the IPWP on a seasonal basis that may account for the differences in time-evolution of the proxy data at respective sites. Both the proxies and simulations suggest that precipitation variability during the September-November (SON) season is important for hydroclimate in Borneo. The preëminence of the SON season suggests that a seasonally lagged relationship between the Indian monsoon and Indian Ocean Walker circulation influences IPWP hydroclimatic variability during the Holocene.

  16. Influence of the Spray Angle on the Characteristics of Atmospheric Plasma Sprayed Hard Material Based Coatings

    NASA Astrophysics Data System (ADS)

    Tillmann, Wolfgang; Vogli, Evelina; Krebs, Benjamin

    2008-12-01

    This paper presents an investigation of the influence of the spray angle on thermally sprayed coatings. Spray beads were manufactured with different spray angles between 90 and 20° by means of atmospheric plasma spraying (APS) on heat-treated mild steel (1.0503). WC-12Co and Cr3C2-10(Ni20Cr) powders were employed as feedstock materials. Every spray bead was characterized by a Gaussian fit. This opens the opportunity to analyze the influence of the spray angle on coating properties. Furthermore, metallographic studies of the surface roughness, porosity, hardness, and morphology were carried out and the deposition efficiency as well as the tensile strength was measured. The thermally sprayed coatings show a clear dependence on the spray angle. A decrease in spray angle changes the thickness, width, and form of the spray beads. The coatings become rougher and their quality decreases.

  17. Surface pretreatment of plastics with an atmospheric pressure plasma jet - Influence of generator power and kinematics

    SciTech Connect

    Moritzer, E., E-mail: elmar.moritzer@ktp.upb.de; Leister, C., E-mail: elmar.moritzer@ktp.upb.de [Kunststofftechnik Paderborn (KTP), University of Paderborn, Warburger Strasse 100, D-33098 Paderborn (Germany)

    2014-05-15

    The industrial use of atmospheric pressure plasmas in the plastics processing industry has increased significantly in recent years. Users of this treatment process have the possibility to influence the target values (e.g. bond strength or surface energy) with the help of kinematic and electrical parameters. Until now, systematic procedures have been used with which the parameters can be adapted to the process or product requirements but only by very time-consuming methods. For this reason, the relationship between influencing values and target values will be examined based on the example of a pretreatment in the bonding process with the help of statistical experimental design. Because of the large number of parameters involved, the analysis is restricted to the kinematic and electrical parameters. In the experimental tests, the following factors are taken as parameters: gap between nozzle and substrate, treatment velocity (kinematic data), voltage and duty cycle (electrical data). The statistical evaluation shows significant relationships between the parameters and surface energy in the case of polypropylene. An increase in the voltage and duty cycle increases the polar proportion of the surface energy, while a larger gap and higher velocity leads to lower energy levels. The bond strength of the overlapping bond is also significantly influenced by the voltage, velocity and gap. The direction of their effects is identical with those of the surface energy. In addition to the kinematic influences of the motion of an atmospheric pressure plasma jet, it is therefore especially important that the parameters for the plasma production are taken into account when designing the pretreatment processes.

  18. An ARPS-CMAQ Modeling Approach for Assessing the Atmospheric Assimilative Capacity of the Beijing Metropolitan Region

    Microsoft Academic Search

    Shuiyuan Cheng; Dongsheng Chen; Jianbing Li; Xiurui Guo; Haiyan Wang

    2007-01-01

    A coupled ARPS–CMAQ modeling system was applied to investigate the atmospheric assimilative capacity (AAC) of PM10 in the Beijing metropolitan region of China. The AAC was defined as the maximum allowable pollutant emission that can be\\u000a discharged to the atmosphere without violating the desired air quality objective in the planning region. The coupled modeling\\u000a system was firstly evaluated through comparing

  19. Titan's atmosphere from Voyager infrared observations. I - The gas composition of Titan's equatorial region

    NASA Astrophysics Data System (ADS)

    Coustenis, A.; Bezard, B.; Gautier, D.

    1989-07-01

    After inferring minor atmospheric-constituent abundances in Titan's equatorial region from Voyager 1 IR spectra, a stratospheric temperature profile is derived. An analysis of three different sections has yielded stratospheric mole fractions for C2H2, C2H4, C2H6, C3H4, C3H8, C4H2, HCN, and CO2; an altitude-dependent CO2 profile has been tested against observations, but no conclusive data on vertical distribution could be extracted. Emission-line formation for all minor components originates from the 1-20 mbar, or 75-200 km, pressure levels.

  20. Influence of the Laurentian Great Lakes on Regional Climate1 Michael Notaro, Kathleen Holman8

    E-print Network

    Wisconsin at Madison, University of

    1 Influence of the Laurentian Great Lakes on Regional Climate1 2 3 4 5 6 7 Michael Notaro, Kathleen #12;2 Abstract47 48 The influence of the Laurentian Great Lakes on climate is assessed by comparing of the diurnal cycle and annual cycle of air temperature. The53 impacts of the Great Lakes on the regional

  1. Influence of ethylene glycol pretreatment on effectiveness of atmospheric pressure plasma treatment of polyethylene fibers

    NASA Astrophysics Data System (ADS)

    Wen, Ying; Li, Ranxing; Cai, Fang; Fu, Kun; Peng, Shujing; Jiang, Qiuran; Yao, Lan; Qiu, Yiping

    2010-03-01

    For atmospheric pressure plasma treatments, the results of plasma treatments may be influenced by liquids adsorbed into the substrate. This paper studies the influence of ethylene glycol (EG) pretreatment on the effectiveness of atmospheric plasma jet (APPJ) treatment of ultrahigh molecular weight polyethylene (UHMWPE) fibers with 0.31% and 0.42% weight gain after soaked in EG/water solution with concentration of 0.15 and 0.3 mol/l for 24 h, respectively. Scanning electron microscopy (SEM) shows that the surface of fibers pretreated with EG/water solution does not have observable difference from that of the control group. The X-ray photoelectron spectroscopy (XPS) results show that the oxygen concentration on the surface of EG-pretreated fibers is increased less than the plasma directly treated fibers. The interfacial shear strength (IFSS) of plasma directly treated fibers to epoxy is increased almost 3 times compared with the control group while that of EG-pretreated fibers to epoxy does not change except for the fibers pretreated with lower EG concentration and longer plasma treatment time. EG pretreatment reduces the water contact angle of UHMWPE fibers. In conclusion, EG pretreatment can hamper the effect of plasma treatment of UHMWPE fibers and therefore longer plasma treatment duration is required for fibers pretreated with EG.

  2. Elemental Compositions of the Martian Surface and Atmosphere and Their Influence on Future Mars Science

    NASA Astrophysics Data System (ADS)

    Boynton, W. V.; Taylor, J.; McLennan, S. M.; Sprague, A. L.; Newsom, H. E.

    2009-12-01

    Landing site selection for future missions, including sample return missions, requires a complete understanding both of the detailed local geology and the regional geological, geophysical, and geochemical context. Orbital imaging and spectroscopic instruments provide essential data about physical properties, local geology, and mineralogy, but only the Mars Odyssey Gamma-Ray Spectrometer (GRS) provides geochemical context by mapping the composition of the Martian near-surface environment. The GRS has provided elemental concentration maps of Mars from approximately 52? south to 52? north. Elements for which maps are available are K, Th, Si, Fe, Ca, Cl, and H, with S and Al in preparation. This is an excellent mix of incompatible elements (K, Th), major elements (Si, Fe, Ca, Al), and elements affected by aqueous processes (H, Cl, S). These data provide information on Martian bulk composition, crust formation and evolution, the composition of the dominant types of igneous rocks, and the intensity of aqueous alteration events. The data show that the surface composition is not uniform even in areas that are heavily mantled in surficial materials, thus arguing against surficial mantling materials originating from a globally homogenized dust component. The implication of this result is that the surficial materials are locally derived and represent the chemical characteristics of the surface rocks. The global K/Th ratio is consistent with previous estimates of Martian bulk composition, a critical component in testing models for planetary accretion. Its relatively narrow range (95% of the surface has K/Th between 4000 and 7000) indicates that aqueous alteration of the surface occurred in short duration events that did not fractionate K from Th. Basalts and sediments derived from basalts make up most of the Martian crust. These observations contribute to addressing fundamental problems in planetary and specifically Martian science, including the evolution of the Martian crust and mantle, planetary accretion, and the role of water on the Martian surface, and emphasize the need for continued direct chemical measurements of the surface, perhaps using orbital elemental measurements as guides for site selection. The GRS gamma-ray data have had a significant and unexpected impact on Mars atmospheric science and general circulation models used to predict Mars’ atmospheric dynamics. We found that Ar is enriched over the winter poles due to the transport of atmosphere into the polar region to replenish the CO2 condensed out of the atmosphere to form the seasonal cap. In the case of the south pole, the enrichment is a factor of six, but surprisingly around LS = 90?, even as the cap is continuing to grow, the Ar diffuses out of the polar region. These data show the value of long-term atmospheric monitoring from orbit.

  3. Influence of meteorological input and wet deposition schemes on atmospheric transport simulations of radionuclides from the Fukushima accident

    NASA Astrophysics Data System (ADS)

    Arnold, Delia; Wotawa, Gerhard; Maurer, Christian; Seibert, Petra

    2013-04-01

    Meteorological data used as input to atmospheric transport models are of decisive importance for the resulting transport and deposition patterns. Dispersion calculations for Cs-137 and Xe-133 released by the Fukushima reactor accidents have been carried out with different global and local meteorological information, and results compared. The different meteorological input data sets are global model output from ECMWF with different horizontal resolutions, down to approximately 0.1 degrees, and GFS with 0.5 deg resolution. They were used to drive the Lagrangian particle dispersion model FLEXPART. A new fix for the wet deposition scheme in FLEXPART was tested in these simulations as well. The dispersion calculations have been compared to gridded Cs-137 deposition data and the few available ambient nuclide concentrations measurements within Japan. For the global-scale transport results, CTBTO IMS radionuclide measurements provided the required evaluation data. The influence of nested higher resolution meteorological data from the near-source region on the long range transport and wet scavenging influence was also studied.

  4. REGIONAL APPLICATION OF A BIOGEOCHEMICAL MODEL (PNET-BGC) TO THE ADIRONDACK REGION OF NEW YORK: RESPONES TO CURRENT AND FUTURE CHANGES IN ATMOSPHERIC DEPOSITION

    EPA Science Inventory

    Understanding the response of soil and surface waters to changes in atmospheric deposition is critical for guiding future legislation on air pollutants. In this study, the regional response of soil and surface waters in 37 lake watersheds in the Adirondack region of New York to c...

  5. Deuterium excess in atmospheric water vapor of a Mediterranean coastal wetland: regional versus local signatures

    NASA Astrophysics Data System (ADS)

    Delattre, H.; Vallet-Coulomb, C.; Sonzogni, C.

    2015-01-01

    Stable isotopes of the water vapor represent a powerful tool for tracing atmospheric vapor origin and mixing processes. Laser spectrometry recently allowed high time resolution measurements, but despite an increasing number of experimental studies, there is still a need for a better understanding of the main drivers of isotopic signal variability at different time scales. We present results of in situ measurements of ?18O and ?D during 36 consecutive days in summer 2011 in atmospheric vapor of a Mediterranean coastal wetland exposed to high evapotranspiration (Camargue, Rhône River delta, France). A calibration protocol was tested and instrument stability was analysed over the period. The mean composition of atmospheric vapor during the campaign is ?18O = -14.66‰ and ?D = -95.4‰, with ?v data plotting clearly above the local meteoric water line, and an average deuterium excess (dv) of 21.9‰. At daily time step, we show a clear separation of isotopic characteristics with respect to the air mass back trajectories, with the Northern air masses providing depleted compositions (?18O = -15.83‰, ?D = -103.5‰) compared to Mediterranean air masses (?18O = -13.13‰, ?D = -86.5‰). There is also a clear separation between dv corresponding to these different air mass origins, but not in the same direction as was previously evidenced from regional rainfall data, with higher dv found for Northern air masses (23.2‰) than for Mediterranean air masses (18.6‰). Based on twenty-four average hourly data, we propose a depiction of typical daily evolution of water vapor isotopic composition. High diurnal variations in dv is attributed to a dominant control of evapotranspiration, over entrainment of free atmosphere. Daily cycles in dv are more pronounced for Mediterranean than for North Atlantic air mass origin and are discussed in terms of local evapotranspiration versus regional signatures. We calculate the composition of the vapor source that produces the day-time increase in dv for the different air mass origins, and propose an atmospheric water and isotopic mass balance.

  6. Retrieving the atmospheric aerosol properties over Beijing region by combining rotational Raman - Mie lidar and CALIPSO

    NASA Astrophysics Data System (ADS)

    Zhang, Yinchao; Li, Dan; Chen, Binglong; Chen, Siying; Chen, He; Guo, Pan

    2013-05-01

    Typically, we use Klett-Fernald method for retrieving aerosol optical properties. However, the results from these methods critically depend on the lidar ratio, thus affecting the accuracy of the inversion results. In this paper, we adopted a new method to retrieve the vertical distribution profiles of aerosol backscatter coefficient, aerosol extinction coefficient and lidar ratio over Beijing region by combining rotational Raman - Mie lidar and CALIPSO(Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations). The results were compared with the results determined by the conventional method, which shows a good agreement. Compared with the conventional method, the results from this new method are more reliable and less noisy, which provide richer information for researching the atmospheric aerosol properties over Beijing region.

  7. Photometric properties of the surface of Io and their influence on line formation in the atmosphere

    NASA Technical Reports Server (NTRS)

    Yung, Y. L.; Goody, R. M.

    1975-01-01

    A quantitative theory is given for line formation in an atmosphere above a surface with backscattering properties. Sufficiently high spatial and spectral resolution spectra of resonance lines in Io region A can yield data on the surface scattering properties as well as the number density of scattering molecules. Macroscopically homogeneous models of scattering from the surface of Io are discussed and it was concluded that multiple reflection from crystal facets is the most likely cause for the observed phase variations of the geometric albedo.

  8. Spatial Variation of Soil Type and Soil Moisture in the Regional Atmospheric Modeling System

    SciTech Connect

    Buckley, R.

    2001-06-27

    Soil characteristics (texture and moisture) are typically assumed to be initially constant when performing simulations with the Regional Atmospheric Modeling System (RAMS). Soil texture is spatially homogeneous and time-independent, while soil moisture is often spatially homogeneous initially, but time-dependent. This report discusses the conversion of a global data set of Food and Agriculture Organization (FAO) soil types to RAMS soil texture and the subsequent modifications required in RAMS to ingest this information. Spatial variations in initial soil moisture obtained from the National Center for Environmental Predictions (NCEP) large-scale models are also introduced. Comparisons involving simulations over the southeastern United States for two different time periods, one during warmer, more humid summer conditions, and one during cooler, dryer winter conditions, reveals differences in surface conditions related to increases or decreases in near-surface atmospheric moisture con tent as a result of different soil properties. Three separate simulation types were considered. The base case assumed spatially homogeneous soil texture and initial soil moisture. The second case assumed variable soil texture and constant initial soil moisture, while the third case allowed for both variable soil texture and initial soil moisture. The simulation domain was further divided into four geographically distinct regions. It is concluded there is a more dramatic impact on thermodynamic variables (surface temperature and dewpoint) than on surface winds, and a more pronounced variability in results during the summer period. While no obvious trends in surface winds or dewpoint temperature were found relative to observations covering all regions and times, improvement in surface temperatures in most regions and time periods was generally seen with the incorporation of variable soil texture and initial soil moisture.

  9. Regional frequency analysis conditioned on large-scale atmospheric or oceanic fields

    NASA Astrophysics Data System (ADS)

    Renard, Benjamin; Lall, Upmanu

    2015-04-01

    Many studies report that hydrologic regimes are modulated by large-scale modes of climate variability such as the El Niño Southern Oscillation (ENSO) or the North Atlantic Oscillation (NAO). Climate-informed frequency analysis models have therefore been proposed to condition the distribution of hydrologic variables on climate indices. However, standard climate indices may be poor predictors in some regions. This paper therefore describes a regional frequency analysis framework that conditions the distribution of hydrologic variables directly on atmospheric or oceanic fields, as opposed to predefined climate indices. This framework is based on a 2-level probabilistic model describing both climate and hydrologic data. The climate dataset (predictor) is typically a time series of atmospheric of oceanic fields defined on a grid over some area, while the hydrologic dataset (predictand) is typically a regional dataset of station data (e.g. annual peak flow at several gauging stations). A Bayesian estimation framework is used, so that a natural quantification of uncertainties affecting hydrologic predictions is available. A case study aimed at predicting the number of autumn flood events in 16 catchments located in Mediterranean France using geopotential heights at 500 hPa over the North-Atlantic region is presented. The temporal variability of hydrologic data is shown to be associated with a particular spatial pattern in the geopotential heights. A cross-validation experiment indicates that the resulting probabilistic climate-informed predictions are skillful: their reliability is acceptable and they are much sharper than predictions based on standard climate indices and baseline predictions that ignore climate information.

  10. Increasing Mississippi river discharge throughout the twenty-first century influenced by changes in climate, land use and atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Tao, B.; Tian, H.; Ren, W.; Yang, J.; Yang, Q.; He, R.; Cai, W. J.; Lohrenz, S. E.

    2014-12-01

    Previous studies have demonstrated that changes in temperature and precipitation (hereafter climate change) would influence river discharge, but the relative importance of climate change, land use, and elevated atmospheric CO2 have not yet been fully investigated. Here we examined how river discharge in the Mississippi River basin in the 21st century might be influenced by these factors using the Dynamic Land Ecosystem Model driven by atmospheric CO2, downscaled GCMs climate and land use scenarios. Our results suggest that river discharge would be substantially enhanced (10.7-59.8%) by the 2090s compared to the recent decade (2000s), though large discrepancies exist among different climate, atmospheric CO2, and land use change scenarios. Our factorial analyses further indicate that the combined effects of land use change and human-induced atmospheric CO2 elevation on river discharge would outweigh climate change effect under the high emission scenario (A2) of Intergovernmental Panel for Climate Change. Our study offers the first attempt to project potential changes in river discharge in response to multiple future environmental changes. It demonstrates the importance of land use change and atmospheric CO2 concentrations in projecting future changes in hydrologic processes. The projected increase river discharge implies that riverine fluxes of carbon, nutrients and pesticide from the MRB to the coastal regions would increase in the future, and thus may influence the states of ocean acidification and hypoxia and deteriorate ocean water quality. Further efforts will also be needed to account for additional environmental factors (such as nitrogen deposition, tropospheric ozone pollution, dam construction, etc.) in projecting changes in the hydrological cycle.

  11. Regional Atmospheric Transport Code for Hanford Emission Tracking (RATCHET). Hanford Environmental Dose Reconstruction Project

    SciTech Connect

    Ramsdell, J.V. Jr.; Simonen, C.A.; Burk, K.W.

    1994-02-01

    The purpose of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate radiation doses that individuals may have received from operations at the Hanford Site since 1944. This report deals specifically with the atmospheric transport model, Regional Atmospheric Transport Code for Hanford Emission Tracking (RATCHET). RATCHET is a major rework of the MESOILT2 model used in the first phase of the HEDR Project; only the bookkeeping framework escaped major changes. Changes to the code include (1) significant changes in the representation of atmospheric processes and (2) incorporation of Monte Carlo methods for representing uncertainty in input data, model parameters, and coefficients. To a large extent, the revisions to the model are based on recommendations of a peer working group that met in March 1991. Technical bases for other portions of the atmospheric transport model are addressed in two other documents. This report has three major sections: a description of the model, a user`s guide, and a programmer`s guide. These sections discuss RATCHET from three different perspectives. The first provides a technical description of the code with emphasis on details such as the representation of the model domain, the data required by the model, and the equations used to make the model calculations. The technical description is followed by a user`s guide to the model with emphasis on running the code. The user`s guide contains information about the model input and output. The third section is a programmer`s guide to the code. It discusses the hardware and software required to run the code. The programmer`s guide also discusses program structure and each of the program elements.

  12. Evidence that local land use practices influence regional climate, vegetation, and stream flow patterns in adjacent natural areas

    USGS Publications Warehouse

    Stohlgren, T.J.; Chase, T.N.; Pielke, R.A., Sr.; Kittel, T.G.F.; Baron, J.S.

    1998-01-01

    We present evidence that land use practices in the plains of Colorado influence regional climate and vegetation in adjacent natural areas in the Rocky Mountains in predictable ways. Mesoscale climate model simulations using the Colorado State University Regional Atmospheric Modelling System (RAMS) projected that modifications to natural vegetation in the plains, primarily due to agriculture and urbanization, could produce lower summer temperatures in the mountains. We corroborate the RAMS simulations with three independent sets of data: (i) climate records from 16 weather stations, which showed significant trends of decreasing July temperatures in recent decades; (ii) the distribution of seedlings of five dominant conifer species in Rocky Mountain National Park, Colorado, which suggested that cooler, wetter conditions occurred over roughly the same time period; and (iii) increased stream flow, normalized for changes in precipitation, during the summer months in four river basins, which also indicates cooler summer temperatures and lower transpiration at landscape scales. Combined, the mesoscale atmospheric/land-surface model, short-term in regional temperatures, forest distribution changes, and hydrology data indicate that the effects of land use practices on regional climate may overshadow larger-scale temperature changes commonly associated with observed increases in CO2 and other greenhouse gases.

  13. Atmospheric correction using near-infrared bands for satellite ocean color data processing in the turbid western Pacific region.

    PubMed

    Wang, Menghua; Shi, Wei; Jiang, Lide

    2012-01-16

    A regional near-infrared (NIR) ocean normalized water-leaving radiance (nL(w)(?)) model is proposed for atmospheric correction for ocean color data processing in the western Pacific region, including the Bohai Sea, Yellow Sea, and East China Sea. Our motivation for this work is to derive ocean color products in the highly turbid western Pacific region using the Geostationary Ocean Color Imager (GOCI) onboard South Korean Communication, Ocean, and Meteorological Satellite (COMS). GOCI has eight spectral bands from 412 to 865 nm but does not have shortwave infrared (SWIR) bands that are needed for satellite ocean color remote sensing in the turbid ocean region. Based on a regional empirical relationship between the NIR nL(w)(?) and diffuse attenuation coefficient at 490 nm (K(d)(490)), which is derived from the long-term measurements with the Moderate-resolution Imaging Spectroradiometer (MODIS) on the Aqua satellite, an iterative scheme with the NIR-based atmospheric correction algorithm has been developed. Results from MODIS-Aqua measurements show that ocean color products in the region derived from the new proposed NIR-corrected atmospheric correction algorithm match well with those from the SWIR atmospheric correction algorithm. Thus, the proposed new atmospheric correction method provides an alternative for ocean color data processing for GOCI (and other ocean color satellite sensors without SWIR bands) in the turbid ocean regions of the Bohai Sea, Yellow Sea, and East China Sea, although the SWIR-based atmospheric correction approach is still much preferred. The proposed atmospheric correction methodology can also be applied to other turbid coastal regions. PMID:22274419

  14. Influences of impedance matching network on pulse-modulated radio frequency atmospheric pressure glow discharges

    NASA Astrophysics Data System (ADS)

    Huo, W. G.; Xu, K.; Sun, B.; Ding, Z. F.

    2012-08-01

    Pulse-modulated RF atmospheric pressure glow discharges (APDGs) were investigated in recent years to reduce the thermal accumulation and extend the operation region of the stable alpha glow mode. Different pulse-modulated voltage and current waveforms were acquired in previous experiments, but no attention was paid to the interpretation. We investigated this issue and associated phenomenon via positive and negative feedback effects derived from varying the series capacitor in the inversely L-shaped matching network used in our pulse-modulated RF APGD source. The evolutions of pulse-modulated RF waveforms were found to be associated with the feedback region and the pulsed plasma absorbed RF power. In the positive feedback region, pulse-modulated RF APGDs are relatively stable. In the negative feedback region, wide spikes as well as undershoots occur in RF voltage and current waveforms and the plasma absorbed RF power. In case of a high RF power discharge with a low modulation frequency, the pulse-modulated RF APGD is extinguished and re-ignited due to the enhanced undershoot during the initial pulse phase. The pulse-modulated RF APGD can transit from positive to negative feedback region in a range of series capacitance. Experimental results are discussed by the aid of equivalent circuit, negative and positive feedback effects.

  15. Influences of impedance matching network on pulse-modulated radio frequency atmospheric pressure glow discharges

    SciTech Connect

    Huo, W. G. [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116023 (China); School of Physics and Electronic Technology, Liaoning Normal University, Dalian 116029 (China); Xu, K.; Sun, B.; Ding, Z. F. [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116023 (China)

    2012-08-15

    Pulse-modulated RF atmospheric pressure glow discharges (APDGs) were investigated in recent years to reduce the thermal accumulation and extend the operation region of the stable alpha glow mode. Different pulse-modulated voltage and current waveforms were acquired in previous experiments, but no attention was paid to the interpretation. We investigated this issue and associated phenomenon via positive and negative feedback effects derived from varying the series capacitor in the inversely L-shaped matching network used in our pulse-modulated RF APGD source. The evolutions of pulse-modulated RF waveforms were found to be associated with the feedback region and the pulsed plasma absorbed RF power. In the positive feedback region, pulse-modulated RF APGDs are relatively stable. In the negative feedback region, wide spikes as well as undershoots occur in RF voltage and current waveforms and the plasma absorbed RF power. In case of a high RF power discharge with a low modulation frequency, the pulse-modulated RF APGD is extinguished and re-ignited due to the enhanced undershoot during the initial pulse phase. The pulse-modulated RF APGD can transit from positive to negative feedback region in a range of series capacitance. Experimental results are discussed by the aid of equivalent circuit, negative and positive feedback effects.

  16. Numerical modeling of solar wind influences on the dynamics of the high-latitude upper atmosphere

    NASA Astrophysics Data System (ADS)

    Förster, M.; Prokhorov, B. E.; Namgaladze, A. A.; Holschneider, M.

    2012-09-01

    Neutral thermospheric wind patterns at high latitudes obtained from cross-track acceleration measurements of the CHAMP satellite above both polar regions are used to deduce statistical neutral wind vorticity distributions and were analyzed in their dependence on the Interplanetary Magnetic Field (IMF). The average pattern confirms the large duskside anticyclonic vortex seen in the average wind pattern and reveals a positive (cyclonic) vorticity on the dawnside, which is almost equal in magnitude to the duskside negative one. The IMF dependence of the vorticity pattern resembles the characteristic field-aligned current (FAC) and ionospheric plasma drift pattern known from various statistical studies obtained under the same sorting conditions as, e.g., the EDI Cluster statistical drift pattern. There is evidence for hemispheric differences in the average magnitudes of the statistical patterns both for plasma drift and even more for the neutral wind vorticity. The paper aims at a better understanding of the globally interconnected complex plasma physical and electrodynamic processes of Earth's upper atmosphere by means of first-principle numerical modeling using the Upper Atmosphere Model (UAM). The simulations of, e.g., thermospheric neutral wind and mass density at high latitudes are compared with CHAMP observations for varying IMF conditions. They show an immediate response of the upper atmosphere and its high sensitivity to IMF changes in strength and orientation.

  17. Influence of annealing atmosphere on the behavior of titanium implanted sapphire

    NASA Astrophysics Data System (ADS)

    Marques, C.; Alves, E.; McHargue, C.; Ononye, L. C.; Monteiro, T.; Soares, J.; Allard, L. F.

    2002-05-01

    Sapphire single crystals with (0 0 0 1) and (0 2 2¯ 1) orientations were implanted at room temperature with several fluences of Ti at 150 keV. For low fluences (up to 1×10 15 Ti +/cm 2) the Ti ions are fully incorporated in Al sites of the lattice and remain stable up to temperatures of the order of 1000 °C as revealed by detailed channeling angular scans. The amorphous state is reached after implantation of 5×10 16 Ti +/cm 2. Annealing in oxidizing atmosphere leads to complete recovery of the amorphous region and the segregation of Ti to the surface. The RBS and TEM pictures show that Ti oxides concentrate at the surface after annealing at 1000 °C. The same annealing in a reducing atmosphere produces a buried layer of Ti precipitates centered at the range of the implanted ions. The damage recovery is hindered by the presence of this layer as shown by the <0 0 0 1> aligned RBS spectrum. The surface layer becomes polycrystalline as the TEM micrographs reveal. Optical absorption measurements show the presence of a broad band centered at 350 nm for the samples annealed in air. This band is absent in the samples annealed in a reducing atmosphere but the background absorption is much higher compared with the samples annealed on air. Photoluminescence (PL) measurements reveal the presence of an emission band centered around 800 nm.

  18. The dynamical influence of the stratospheric polar vortex on the atmospheric global circulation

    NASA Astrophysics Data System (ADS)

    Villarin, Jose Tizon

    The stratospheric vortex is far more than an ordinary circumpolar current that reacts passively to forcing from the troposphere. It is a vigorously active circulation whose dynamics dominates the winter stratosphere and extends all the way down to the troposphere. Transient distortions and off-polar displacements of this vortex structure lead to planetary scale potential vorticity (PV) anomalies in the polar stratosphere. These PV perturbations in turn generate globally extensive circulation anomalies whose scale and magnitude can be determined by the method of PV inversion. Results of PV inversion show that the anomalous circulations induced by these stratospheric PV anomalies are vertically and laterally extensive enough to influence the tropopause and the subtropical stratosphere. The vertical impact is of a planetary scale and is strongest directly below the vortex edge at high latitudes, extending substantially down into the midlatitude tropopause. Contour advection (CA) calculations also indicate a significant stratospheric influence on the horizontal transport of middle and high latitude tropopause air. Only those vortex PV anomalies from the lower to middle stratosphere are found to be important for tropopause dynamics. The lateral impact of these vortex perturbations is likewise extensive, tunneling through the midlatitude surf zone into the subtropical stratosphere. Combined PV inversion and CA calculations demonstrate the sheer dominance of the vortex in bringing about the poleward entrainment of subtropical tongues of air during wave events in the polar stratosphere. This vortex influence is clearly non- local, so that even wave distortion events that leave the vortex well confined within the middle latitudes are observed to excite subtropical waves. The poleward migration of these planetary scale tongues of subtropical air also generates anomalous circulations that influence their own movement. This extensive dynamical impact of the stratospheric vortex has important implications for our current understanding of the atmospheric global circulation. Aside from affecting a central climate regulation mechanism such as the meridional mixing of radiatively important tracers, this stratospheric influence may also be crucial to the dynamics of planetary waves and how these waves modulate the large scale circulation of our atmosphere.

  19. Influence of radioactivity on surface charging and aggregation kinetics of particles in the atmosphere.

    PubMed

    Kim, Yong-Ha; Yiacoumi, Sotira; Lee, Ida; McFarlane, Joanna; Tsouris, Costas

    2014-01-01

    Radioactivity can influence surface interactions, but its effects on particle aggregation kinetics have not been included in transport modeling of radioactive particles. In this research, experimental and theoretical studies have been performed to investigate the influence of radioactivity on surface charging and aggregation kinetics of radioactive particles in the atmosphere. Radioactivity-induced charging mechanisms have been investigated at the microscopic level, and heterogeneous surface potential caused by radioactivity is reported. The radioactivity-induced surface charging is highly influenced by several parameters, such as rate and type of radioactive decay. A population balance model, including interparticle forces, has been employed to study the effects of radioactivity on particle aggregation kinetics in air. It has been found that radioactivity can hinder aggregation of particles because of similar surface charging caused by the decay process. Experimental and theoretical studies provide useful insights into the understanding of transport characteristics of radioactive particles emitted from severe nuclear events, such as the recent accident of Fukushima or deliberate explosions of radiological devices. PMID:24308778

  20. Sensitivity of regional meteorology and atmospheric composition during the DISCOVER-AQ period to subgrid-scale cloud-radiation interactions

    NASA Astrophysics Data System (ADS)

    Huang, X.; Allen, D. J.; Herwehe, J. A.; Alapaty, K. V.; Loughner, C.; Pickering, K. E.

    2014-12-01

    Subgrid-scale cloudiness directly influences global and regional atmospheric radiation budgets by attenuating shortwave radiation, leading to suppressed convection, decreased surface precipitation as well as other meteorological parameter changes. We use the latest version of WRF (v3.6, Apr 2014), which incorporates the Kain-Fritsch (KF) convective parameterization to provide subgrid-scale cloud fraction and condensate feedback to the rapid radiative transfer model-global (RRTMG) shortwave and longwave radiation schemes. We apply the KF scheme to simulate the DISCOVER-AQ Maryland field campaign (July 2011), and compare the sensitivity of meteorological parameters to the control run that does not include subgrid cloudiness. Furthermore, we will examine the chemical impact from subgrid cloudiness using a regional chemical transport model (CMAQ). There are several meteorological parameters influenced by subgrid cumulus clouds that are very important to air quality modeling, including changes in surface temperature that impact biogenic emission rates; changes in PBL depth that affect pollutant concentrations; and changes in surface humidity levels that impact peroxide-related reactions. Additionally, subgrid cumulus clouds directly impact air pollutant concentrations by modulating photochemistry and vertical mixing. Finally, we will compare with DISCOVER-AQ flight observation data and evaluate how well this off-line CMAQ simulation driven by WRF with the KF scheme simulates the effects of regional convection on atmospheric composition.

  1. R and D -- Seismic report on the influence of the source region on regional seismic waveforms as inferred from modeling

    SciTech Connect

    App, F.N.; Jones, E.M.; Bos, R.J.

    1997-11-01

    The identification of an underground nuclear test from its seismic signal recorded by seismometers at regional distances is one of the fundamental scientific goals of the Comprehensive Test Ban Treaty R and D Program. The work being reported here addresses the issue of event discrimination through the use of computer models that use realistic simulations of nuclear explosions in various settings for the generation of near-regional and regional synthetic seismograms. The study exercises some unique, recently developed computer modeling capabilities that heretofore have not been available for discrimination studies. A variety of source conditions and regional paths are investigated. Under the assumptions of the study, conclusions are: (1) spall, non-linear deformation, and depth-of-burial do not substantially influence the near-regional signal and (2) effects due to basins along the regional path very much dominate over source region geology in influencing the signal at regional distances. These conclusions, however, are relevant only for the frequencies addressed, which span the range from 0.1 to 1 Hz for the regional calculations and 0.1 to 3 Hz for the near-regional calculations. They also are relevant only for the crudely ``China-like`` basin, crust, and mantle properties used in the study. If it is determined that further investigations are required, researchers may use this study as a template for such work.

  2. Morphology and Chemical composition of Atmospheric Particles over Semi-Arid region (Jaipur, Rajasthan) of India

    NASA Astrophysics Data System (ADS)

    Mishra, S. K.; Agnihotri, R.; Yadav, P.; Singh, S.; Tawale, J. S.; Rashmi, R.; Prasad, M.; Arya, B. C.; Mishra, N.

    2012-12-01

    Uncertainties associated with the radiative forcing of atmospheric dust particles is highest, owing to lack of region-specific dust morphology (particle shape, size) and mineralogy (chemical composition) database, needed for modeling their optical properties (Mishra and Tripathi, 2008). To fill this gap for the Indian region, we collected atmospheric particles (with aerodynamic size <5um, PM5 and a few bulk particles; TSP) from seven sites of Jaipur and nearby locales (semi-arid region, in the vicinity of Thar Desert of Rajasthan) at varying altitude, during late winters of ca. 2012. PM5 particles were collected on Teflon filters (for bulk chemical analyses), while pure Tin substrates (~1×1 mm2) were used for investigating individual particle morphology. Using Scanning Electron Microscope equipped with Energy Dispersive X ray (SEM-EDX) facility at NPL, images of individual particles were recorded and the morphological parameters (e.g. Aspect ratio; AR, Circulatory parameter; CIR.) were retrieved following Okada et al. (2001), whereas chemical compositions of individual particles were determined by EDX and bulk samples by X ray fluorescence (XRF). The geometrical size distributions of atmospheric particles were generated for each site. Based on NIST (National Institute of Standard and Technology, USA) morphology database, the site-specific individual particle shapes reveal predominance of "Layered" (calcite and quartz rich), "Angular" structures (quartz rich) and "Flattened" particles over all the sites. Particles were found to be highly non-spherical with irregular shapes (CIR varying from 1 to 0.22 with median value ~0.76; AR varying from 1 to 5.4 with median value ~1.64). Noteworthy to mention, that unit values of AR and CIR represent spherical particles. Chemical analyses of PM5 particles revealed dominance of crustal elements e.g. Si, Al, Fe, Ca, Mg, in general. Particles over Kukas Hill (27.027° N, 75.919° E; ~800 MAGL) showed highest Fe mass fractions (~43%), i.e. a key element (in form of hematite; Fe2O3) for solar (visible) energy absorption and thus heating the atmosphere. The retrieved morphological parameters help to construct particle shape and number size distribution that are highly useful to reduce the uncertainty in radiative forcing of dust particles appreciably when combined with particle chemical composition as suggested by Kalashnikova and Sokolik (2004). References : Mishra, S. K., and S. N. Tripathi (2008), Modeling optical properties of mineral dust over the Indian Desert, J. Geophys. Res., 113, D23201, 19 PP., doi:10.1029/2008JD010048. Okada, K., J. Heintzenberg, K. Kai, and Y. Qin (2001), Shape of atmospheric mineral particles collected in three Chinese arid-regions, Geophys. Res. Lett., 28, 3123-3126 Kalashnikova OV, Sokolik IN. (2004) Modeling the radiative properties of nonspherical soil-derived mineral aerosols, J Quant Spectrosc Radiat Transfer, 87, 137-66.

  3. Atmospheric discharge and dispersion of radionuclides during the Fukushima Dai-ichi Nuclear Power Plant accident. Part II: verification of the source term and analysis of regional-scale atmospheric dispersion.

    PubMed

    Terada, Hiroaki; Katata, Genki; Chino, Masamichi; Nagai, Haruyasu

    2012-10-01

    Regional-scale atmospheric dispersion simulations were carried out to verify the source term of (131)I and (137)Cs estimated in our previous studies, and to analyze the atmospheric dispersion and surface deposition during the Fukushima Dai-ichi Nuclear Power Plant accident. The accuracy of the source term was evaluated by comparing the simulation results with measurements of daily and monthly surface depositions (fallout) over land in eastern Japan from March 12 to April 30, 2011. The source term was refined using observed air concentrations of radionuclides for periods when there were significant discrepancies between the calculated and measured daily surface deposition, and when environmental monitoring data, which had not been used in our previous studies, were now available. The daily surface deposition using the refined source term was predicted mostly to within a factor of 10, and without any apparent bias. Considering the errors in the model prediction, the estimated source term is reasonably accurate during the period when the plume flowed over land in Japan. The analysis of regional-scale atmospheric dispersion and deposition suggests that the present distribution of a large amount of (137)Cs deposition in eastern Japan was produced primarily by four events that occurred on March 12, 15-16, 20, and 21-23. The ratio of wet deposition to the total varied widely depending on the influence by the particular event. PMID:22721917

  4. Analysis of seasonality and annual mean distribution of atmospheric potential oxygen (APO) in the Pacific region

    NASA Astrophysics Data System (ADS)

    Tohjima, Yasunori; Minejima, Chika; Mukai, Hitoshi; Machida, Toshinobu; Yamagishi, Hiroaki; Nojiri, Yukihiro

    2012-12-01

    We present a data set of atmospheric potential oxygen (APO = O2 + 1.1 × CO2) based on the atmospheric O2/N2 and CO2 measurements of flask samples collected at two monitoring stations in Japan and on commercial cargo ships sailing between Japan and U.S./Canada and Australia/New Zealand. Since APO is invariant with respect to the terrestrial biotic exchange, its variation mainly reflects the spatiotemporal distribution in the air-to-sea gas exchange. From the observed APO for the years 2002-2008, we find: (1) elevated annual mean values near the equator, (2) elevated annual mean values and large seasonal amplitudes in the northwestern North Pacific, and (3) a deep trough of low annual mean values at latitudes 20-40°N in the Western Pacific. In addition, latitudinal distributions in the timing of the observed seasonal maximum and minimum show asymmetric patterns across the equator. Comparing these observations with a series of simulated APO generated in the NIES99 atmospheric transport model driven by a set of climatological oceanic O2 and CO2 flux fields, we find a good agreement except for the observed deep trough at the midlatitude. Simulations with different transport mechanisms and fluxes reveal that the seasonal covariation between oceanic O2 flux and atmospheric transport contribute significantly to the observed APO variations in the northern North Pacific; also the seasonal variation in the meridional transport affects the latitudinal difference in the seasonal cycle. The observed latitudinal gradient of the annual mean APO in the Southern Hemisphere is better reproduced by the model based on the recently revised ocean CO2 flux distribution than that based on the previous CO2 flux distribution. The observed APO trough at 36°N in the Western Pacific is about 10 per meg lower than the simulation with the more recent pCO2 data, suggesting the existence of additional APO sinks in that latitudinal region. Indeed, a model simulation performed with an additional ocean O2 sink flux of about 30 Tmol yr-1 within the region (30-50°N, 120-180°E) reproduces considerably well the observed APO trough.

  5. Robust influences of superparameterized rainfall variability and intensity on land-atmosphere energetics including soil moisture, surface fluxes, and temperature

    NASA Astrophysics Data System (ADS)

    Kooperman, Gabriel; Pritchard, Michael

    2015-04-01

    Land-atmosphere coupling energetics can play critical roles in mediating local weather and climate. Interactions at this hydrologic interface impact the availability of freshwater, droughts, floods, and temperature extremes. Predicting how the hydrological cycle will respond to climate change requires a realistic representation of these complex energy exchange mechanisms in global climate models (GCMs). Conventional GCMs suggest that regions of strong coupling (i.e. where local rainfall and soil moisture fluctuations are correlated) will be most sensitive to climate change. However, these models do not capture some forms of organized convection and are known to distort the diurnal character of rainfall over land. Second-order characteristics of rainfall (variability, frequency, timing, and intensity), in addition to time-integrated climatology, can have a significant impact on the hydrologic cycle. They determine whether rainwater infiltrates the soil or runs off the surface and how much water collected on the vegetation canopy is available for re-evaporation. Here we investigate land-atmosphere interactions in a GCM that explicitly resolves convection, captures organized storms, and improves the diurnal cycle and intensity distribution of rain. In this multi-scale modeling approach called super-parameterization (SP), simplified cloud resolving models are embedded in each grid column of the NCAR Community Atmosphere Model (CAM) to replace conventional parameterizations. SP-CAM captures the broad rainfall intensity distribution and extreme events that are missing in conventional CAM, especially during the mid-latitude summer and in the tropics, exerting a strong influence during the growing season. More intense rainfall reduces canopy interception (and the re-evaporation of rainwater that is often exaggerated in GCMs), increases the rate of rainfall reaching the ground and thus running off the surface, and generally increases the demand on transpiration. As a result, SP-CAM amplifies the Bowen ratio relative to conventional CAM, which is enhanced further with climate change. This amplified Bowen ratio appears to be a robust effect of SP. It is consistent across many regions and model versions with different resolution, cloud microphysics, and land-surface processes, broadening the temperature distribution to include more extreme heat events in SP-CAM.

  6. Passive margin uplifts and their influence on climatic change and weathering patterns of tropical shield regions

    Microsoft Academic Search

    Yanni Gunnell

    1998-01-01

    Large scale plateau uplift influences long-term atmospheric circulation patterns. Recent speculation on the role of passive margin mountains in initiating late Cenozoic glaciation around the North Atlantic adds to the debate on the connections between tectonics and climate patterns, and calls for broadening the scope of examining causes of climate change to include other existing passive margins. Three examples from

  7. Influence of scattering, atmospheric refraction, and ground effect on sound propagation through a pine forest.

    PubMed

    Swearingen, Michelle E; White, Michael J

    2007-07-01

    Sound propagation through a forest is affected by the microclimate in the canopy, scattering by trunks and stems, and ground reflection. Each of these effects is such a strong contributor to the attenuation of sound that mutual interactions between the phenomena could become important. A sound propagation model for use in a forest has been developed that incorporates scattering from trunks and branches and atmospheric refraction by modifying the effective wave number in the Green's function parabolic equation model. The ground effect for a hard-backed pine straw layer is approximated as a local reaction impedance condition. Comparisons to experimental data are made for frequencies up to 4,200 Hz. Cumulative influences of the separate phenomena are examined. The method developed in this paper is compared to previously published methods. The overall comparison with spectral transmission data is good, suggesting that the model captures the necessary details. PMID:17614470

  8. Magnetic resonance investigation of Zn1-xFexO properties influenced by annealing atmosphere

    NASA Astrophysics Data System (ADS)

    Raita, O.; Popa, A.; Toloman, D.; Stan, M.; Giurgiu, L. M.

    2013-11-01

    ZnO is an attractive system for a wide variety of practical applications, being a chemically stable oxide semiconductor. It has been shown that Fe doping produces ferromagnetic semiconductor at room temperature. This material, therefore, has the potential for use in spintronic devices such as spin transistors, spin light emitting diodes, very high density nonvolatile semiconductor memory and optical emitters. It is believed that oxygen vacancies and substitutional incorporation are important to produce ferromagnetism in semiconductor oxide doped with transition metal ions. The present paper reports detailed electron paramagnetic resonance investigations (EPR) of the samples in order to investigate how annealing atmosphere (Air and Argon) influenced the magnetic behavior of the samples. X-band electron paramagnetic resonance (EPR) studies of Fe3+ ions in Zn1-xFexO powders with x = 1%, 3% is reported. These samples are interesting to investigate as Fe doping produce ferromagnetism in ZnO, making a promising ferromagnetic semiconductor at room temperature.

  9. Influence of processing gases on the properties of cold atmospheric plasma SiOxCy coatings

    NASA Astrophysics Data System (ADS)

    Hamze, H.; Jimenez, M.; Deresmes, D.; Beaurain, A.; Nuns, N.; Traisnel, M.

    2014-10-01

    Thin layers of SiOxCy (y = 4-x and 3 ? x ? 4) were applied using a cold atmospheric plasma torch on glass substrates. The aim was to investigate using Atomic Force Microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (Tof-Sims) the influence of the gases used on the morphology and composition of the deposits. A hexamethyldisilane (HMDS) precursor was injected in post-discharge in an air or nitrogen plasma using a carrier gas (air or nitrogen) and was applied on the substrate previously pre-treated by an air or nitrogen plasma. The carrier gas and plasma gas flows and the distance between the substrate and the plasma torch, the scanning speed, and the precursor flows were kept constant during the study. The gas used during activation pre-treatment showed no particular influence on the characteristics of the deposit. When air is used both as plasma and carrier gas, the coating layer is thicker (96 nm) than when nitrogen is used (64 nm). It was also evidenced that the gas carrying the precursor has little influence on the hydrophobicity of the coating, contrary to the plasma gas. The latter significantly influences the surface characteristics of the coatings. When air is used as plasma gas, a compact coating layer is obtained and the surface has a water contact angle (WCA) of 82°. When nitrogen is used, the deposit is more hydrophobic (WCA of 100°) and the deposit morphology is different. This increase in hydrophobicity could be correlated to the increase of Sisbnd Osbnd C bonds in the upper surface layers evidenced by XPS analyzes. This observation was then confirmed by Tof-Sims analyzes carried out on these thin layers. A uniform distribution of Carbons in the siloxane coating could also be observed using Tof-Sims 2D reconstruction images of cross sections of the deposited layers.

  10. Influence of the solar activity on the green atmospheric airglow emission

    NASA Astrophysics Data System (ADS)

    Stoeva, P.; Mikhalev, A.; Benev, B.; Medvedeva, I.; Mishin, V.

    Middle latitude airglow emissions are sensitive to thermal and helio-geophysical conditions including atmospheric gravity waves vertical perturbations and conductivity seismic activity etc The investigation of their variability presents an effective method of studying physical and physico-chemical properties of the middle and upper Earth s atmosphere The nighttime airglow emissions from the upper mesosphere and lower thermosphere are dominantly produced through reactions driven by the recombination of atomic oxygen to its molecular form Intensities of the O 1 S 5577 AA emission has been observed at Stara Zagora Bulgaria by zenith tilting photometer during the period of July 2001 -- May 2002 23 rd Solar Cycle maximum Measurements from 143 nights have been used to analyse the nocturnal day to day and seasonal variations of the oxygen green emission line In order to avoid the dynamical influence of tides on the daily variations monthly mean values have been derived from averaged night intensities taken in 2 hour time interval 21-23UT The same analysis has been conducted using data measured at Irkutsk Russia at 50 r latitude and 70 r difference in geographic longitude in the same time period Semiannual oscillations have been well outlined in the two emissions showing equinoctial maxima The large green line intensity observed at Irkutsk in December and partly in January is associated with the stratospheric warming Correlation between green line intensities relative sunspot number and F10 7 radio emission

  11. Variability of atmospheric greenhouse gases as a biogeochemical processing signal at regional scale in a karstic ecosystem

    NASA Astrophysics Data System (ADS)

    Borràs, Sílvia; Vazquez, Eusebi; Morguí, Josep-Anton; Àgueda, Alba; Batet, Oscar; Cañas, Lídia; Curcoll, Roger; Grossi, Claudia; Nofuentes, Manel; Occhipinti, Paola; Rodó, Xavier

    2015-04-01

    The South-eastern area of the Iberian Peninsula is an area where climatic conditions reach extreme climatic conditions during the year, and is also heavily affected by the ENSO and NAO. The Natural Park of Cazorla, Segura de la Sierra and Las Villas is located in this region, and it is the largest protected natural area in Spain (209920 Ha). This area is characterized by important climatic and hydrologic contrasts: although the mean annual precipitation is 770 nm, the karstic soils are the main cause for water scarcity during the summer months, while on the other hand it is in this area where the two main rivers of Southern Spain, the Segura and the Guadalquivir, are born. The protected area comprises many forested landscapes, karstic areas and reservoirs like Tranco de Beas. The temperatures during summer are high, with over 40°C heatwaves occurring each year. But during the winter months, the land surface can be covered by snow for periods of time up until 30 days. The ENSO and NAO influences cause also an important inter annual climatic variability in this area. Under the ENSO, autumnal periods are more humid while the following spring is drier. In this area vegetal Mediterranean communities are dominant. But there are also a high number of endemic species and derelict species typical of temperate climate. Therefore it is a protected area with high specific diversity. Additionally, there is an important agricultural activity in the fringe areas of the Natural Park, mainly for olive production, while inside the Park this activity is focused on mountain wheat production. Therefore the diverse vegetal communities and landscapes can easily be under extreme climatic pressures, affecting in turn the biogeochemical processes at the regional scale. The constant, high-frequency monitoring of greenhouse gases (GHG) (CO2 and CH4) integrates the biogeochemical signal of changes in this area related to the carbon cycle at the regional scale, capturing the high diversity of landscapes and climatic variability. The monitoring is carried out in one of the stations of the ClimaDat network, which consists of eight GHG monitoring stations in highly preserved ecosystems which are very sensitive to climate change in Spain. This constant monitoring will allow relating changes in terrestrial ecosystems, hydrological processes and atmospheric transport of GHG. The goal of the presentation is to show the results obtained since September 2013 through continuous monitoring, focusing on the seasonal changes in precipitation, temperature, and CO2 and CH4 changes in atmospheric concentrations.

  12. Atmospheric conditions associated with extreme fire activity in the Western Mediterranean region.

    PubMed

    Amraoui, Malik; Pereira, Mário G; DaCamara, Carlos C; Calado, Teresa J

    2015-08-15

    Active fire information provided by TERRA and AQUA instruments on-board sun-synchronous polar MODIS platform is used to describe fire activity in the Western Mediterranean and to identify and characterize the synoptic patterns of several meteorological fields associated with the occurrence of extreme fire activity episodes (EEs). The spatial distribution of the fire pixels during the period of 2003-2012 leads to the identification of two most affected sub-regions, namely the Northern and Western parts of the Iberian Peninsula (NWIP) and Northern Africa (NAFR). The temporal distribution of the fire pixels in these two sub-regions is characterized by: (i) high and non-concurrent inter- and intra-annual variability with maximum values during the summer of 2003 and 2005 in NWIP and 2007 and 2012 in NAFR; and, (ii) high intra-annual variability dominated by a prominent annual cycle with a main peak centred in August in both sub-regions and a less pronounced secondary peak in March only evident in NWIP region. The 34 EEs identified were grouped according to the location, period of occurrence and spatial configuration of the associated synoptic patterns into 3 clusters (NWIP-summer, NWIP-winter and NAFR-summer). Results from the composite analysis reveal similar fire weather conditions (statistically significant positive anomalies of air temperature and negative anomalies of air relative humidity) but associated with different circulation patterns at lower and mid-levels of the atmosphere associated with the occurrence of EEs in each cluster of the Western Mediterranean region. PMID:25889542

  13. The National Science Foundation's Coupling, Energetics and Dynamics of Atmospheric Regions (CEDAR) Student Community

    NASA Astrophysics Data System (ADS)

    Sox, L.; Duly, T.; Emery, B.

    2014-12-01

    The National Science Foundation sponsors Coupling, Energetics, and Dynamics of Atmospheric Regions (CEDAR) Workshops, which have been held every summer, for the past 29 years. CEDAR Workshops are on the order of a week long and at various locations with the goal of being close to university campuses where CEDAR type scientific research is done. Although there is no formal student group within the CEDAR community, the workshops are very student-focused. Roughly half the Workshop participants are students. There are two Student Representatives on the CEDAR Science Steering Committee (CSSC), the group of scientists who organize the CEDAR Workshops. Each Student Representative is nominated by his or her peers, chosen by the CSSC and then serves a two year term. Each year, one of the Student Representatives is responsible for organizing and moderating a day-long session targeted for students, made up of tutorial talks, which aim to prepare both undergraduate and graduate students for the topics that will be discussed in the main CEDAR Workshop. The theme of this session changes every year. Past themes have included: upper atmospheric instrumentation, numerical modeling, atmospheric waves and tides, magnetosphere-ionosphere coupling, equatorial aeronomy and many others. Frequently, the Student Workshop has ended with a panel of post-docs, researchers and professors who discuss pressing questions from the students about the next steps they will take in their careers. As the present and past CSSC Student Representatives, we will recount a brief history of the CEDAR Workshops, our experiences serving on the CSSC and organizing the Student Workshop, a summary of the feedback we collected about the Student Workshops and what it's like to be student in the CEDAR community.

  14. Grassland/atmosphere response to changing climate: Coupling regional and local scales. Final report

    SciTech Connect

    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.

  15. Atmospheric sulfur hexafluoride in-situ measurements at the Shangdianzi regional background station in China.

    PubMed

    Yao, Bo; Zhou, Lingxi; Xia, Lingjun; Zhang, Gen; Guo, Lifeng; Liu, Zhao; Fang, Shuangxi

    2014-12-01

    We present in-situ measurements of atmospheric sulfur hexafluoride (SF6) conducted by an automated gas chromatograph-electron capture detector system and a gas chromatography/mass spectrometry system at a regional background site, Shangdianzi, in China, from June 2009 to May 2011, using the System for Observation of Greenhouse gases in Europe and Asia and Advanced Global Atmospheric Gases Experiment (AGAGE) techniques. The mean background and polluted mixing ratios for SF6 during the study period were 7.22 × 10?¹² (mol/mol, hereinafter) and 8.66 × 10?¹², respectively. The averaged SF6 background mixing ratios at Shangdianzi were consistent with those obtained at other AGAGE stations located at similar latitudes (Trinidad Head and Mace Head), but larger than AGAGE stations in the Southern Hemisphere (Cape Grim and Cape Matatula). SF6 background mixing ratios increased rapidly during our study period, with a positive growth rate at 0.30 × 10?¹² year?¹. The peak to peak amplitude of the seasonal cycle for SF6 background conditions was 0.07 × 10?¹², while the seasonal fluctuation of polluted conditions was 2.16 × 10?¹². During the study period, peak values of SF6 mixing ratios occurred in autumn when local surface horizontal winds originated from W/WSW/SW/SWS/S sectors, while lower levels of SF6 mixing ratios appeared as winds originated from N/NNE/NE/ENE/E sectors. PMID:25499493

  16. Winter-spring cyclonic variability in the Mediterranean-Black Sea region associated with global processes in the ocean-atmosphere system

    NASA Astrophysics Data System (ADS)

    Voskresenskaya, E. N.; Maslova, V. N.

    2011-08-01

    Using global NCEP/NCAR reanalysis data set on 1000 hPa geopotential height (1948-2006), cyclones in the Mediterranean and Black Sea regions were detected and their main characteristics (frequency, depth, integrated area) were calculated. Analysis of their interannual-multidecadal variability in January-March associated with global processes in the ocean-atmosphere system was done. It was shown that North Atlantic Oscillation (NAO) manifests in the Black Sea region mainly in the variability of frequency of cyclones while in the Mediterranean - in the interannual anomalies of cyclones' depth and area. Joint NAO and El Nino - Southern Oscillation (ENSO) influence is responsible for about 20-45% of cyclones' frequency variance in the Black Sea region, and in the Mediterranean region for up to 10-25 and 20-30% of the depth and area variance, accordingly. As a result of using a new approach to study ENSO manifestations based on El Nino classification, correlation coefficients between characteristics of cyclones and Southern Oscillation index (SOI) increase at least twice. The influence of the Pacific Decadal and Atlantic Multidecadal Oscillations on variability of cyclonic activity in the Mediterranean-Black Sea region manifests in considerable differences of cyclones' characteristics and their typical location.

  17. Dynamic coupling of regional atmosphere to biosphere in the new generation regional climate system model REMO-iMOVE

    NASA Astrophysics Data System (ADS)

    Wilhelm, C.; Rechid, D.; Jacob, D.

    2013-05-01

    The main objective of this study is the coupling of the regional climate model REMO to a 3rd generation land surface scheme and the evaluation of the new model version of REMO, called REMO with interactive MOsaic-based VEgetation: REMO-iMOVE. Attention is paid to the documentation of the technical aspects of the new model constituents and the coupling mechanism. We compare simulation results of REMO-iMOVE and of the reference version REMO2009, to investigate the sensitivity of the regional model to the new land surface scheme. An 11 yr climate model run (1995-2005), forced with ECMWF ERA-Interim lateral boundary conditions, over Europe in 0.44° resolution of both model versions was carried out, to represent present day European climate. The result of these experiments are compared to multiple temperature, precipitation, heat flux and leaf area index observation data, to determine the differences in the model versions. The new model version has further the ability to model net primary productivity for the given plant functional types. This new feature is thoroughly evaluated by literature values of net primary productivity of different plant species in European climatic regions. The new model version REMO-iMOVE is able to model the European climate in the same quality as the parent model version REMO2009 does. The differences in the results of the two model versions stem from the differences in the dynamics of vegetation cover and density and can be distinct in some regions, due to the influences of these parameters to the surface heat and moisture fluxes. The modeled inter-annual variability in the phenology as well as the net primary productivity lays in the range of observations and literature values for most European regions. This study also reveals the need for a more sophisticated soil moisture representation in the newly developed model version REMO-iMOVE to be able to treat the differences in plant functional types. This gets especially important if the model will be used in dynamic vegetation studies.

  18. Impact of soil moisture–atmosphere coupling on European climate extremes and trends in a regional climate model

    Microsoft Academic Search

    E. B. Jaeger; S. I. Seneviratne

    2011-01-01

    Processes acting at the interface between the land surface and the atmosphere have a strong impact on the European summer\\u000a climate, particularly during extreme years. These processes are to a large extent associated with soil moisture (SM). This\\u000a study investigates the role of soil moisture–atmosphere coupling for the European summer climate over the period 1959–2006\\u000a using simulations with a regional

  19. Ambient concentrations of atmospheric ammonia, nitrogen dioxide and nitric acid in an intensive agricultural region

    NASA Astrophysics Data System (ADS)

    Zbieranowski, Antoni L.; Aherne, Julian

    2013-05-01

    The spatial and temporal distribution of ambient atmospheric gaseous reactive nitrogen (Nr) species concentrations (ammonia [NH3], nitrogen dioxide [NO2] and nitric acid [HNO3]) were measured at the field scale in an intensive agricultural region in southern Ontario, Canada. Atmospheric concentrations were measured with the Willems badge diffusive passive sampler (18 sites for NH3, 9 sites for NO2 and HNO3) for one year (April 2010-March 2011; under a two week measurement frequency) within a 15 km × 15 km area. Dry deposition was calculated using the inferential method and estimated across the entire study area. The spatial distribution of emission sources associated with agricultural activity resulted in high spatial variability in annual average ambient NH3 concentrations (<3->8 ?g m-3 within a 2 km distance, coefficient of variation ˜50%) and estimated dry deposition (4-13 kg N ha-1 yr-1) between sample sites. In contrast, ambient concentrations and deposition of both NO2 (˜5.2->6.5 ?g m-3; 1.0-1.5 kg N ha-1 yr-1) and HNO3 (0.6-0.7 ?g m-3; 0.5-1 kg N ha-1 yr-1) had low variability (coefficient of variation <10%). The observed NH3 concentrations accounted for ˜70% of gaseous Nr dry deposition. High NH3 concentrations suggest that reduced nitrogen species (NHx) will continue to make up an increasing fraction of Nr deposition within intensive agricultural regions in southern Ontario under legislated nitrogen oxide emission reductions. Further, estimated total inorganic Nr deposition (15-28 kg N ha-1 yr-1) may lead to potential changes in soil processes, nutrient imbalance and altered composition of mycorrhiza and ground vegetation within adjacent semi-natural ecosystems (estimated at ˜10% of the study area).

  20. Influence of daily versus monthly fire emissions on atmospheric model applications in the tropics

    NASA Astrophysics Data System (ADS)

    Marlier, M. E.; Voulgarakis, A.; Faluvegi, G.; Shindell, D. T.; DeFries, R. S.

    2012-12-01

    Fires are widely used throughout the tropics to create and maintain areas for agriculture, but are also significant contributors to atmospheric trace gas and aerosol concentrations. However, the timing and magnitude of fire activity can vary strongly by year and ecosystem type. For example, frequent, low intensity fires dominate in African savannas whereas Southeast Asian peatland forests are susceptible to huge pulses of emissions during regional El Niño droughts. Despite the potential implications for modeling interactions with atmospheric chemistry and transport, fire emissions have commonly been input into global models at a monthly resolution. Recognizing the uncertainty that this can introduce, several datasets have parsed fire emissions to daily and sub-daily scales with satellite active fire detections. In this study, we explore differences between utilizing the monthly and daily Global Fire Emissions Database version 3 (GFED3) products as inputs into the NASA GISS-E2 composition climate model. We aim to understand how the choice of the temporal resolution of fire emissions affects uncertainty with respect to several common applications of global models: atmospheric chemistry, air quality, and climate. Focusing our analysis on tropical ozone, carbon monoxide, and aerosols, we compare modeled concentrations with available ground and satellite observations. We find that increasing the temporal frequency of fire emissions from monthly to daily can improve correlations with observations, predominately in areas or during seasons more heavily affected by fires. Differences between the two datasets are more evident with public health applications: daily resolution fire emissions increases the number of days exceeding World Health Organization air quality targets.

  1. On transient events in the upper atmosphere generated away of thunderstorm regions

    NASA Astrophysics Data System (ADS)

    Morozenko, V.; Garipov, G.; Khrenov, B.; Klimov, P.; Panasyuk, M.; Sharakin, S.; Zotov, M.

    2011-12-01

    Experimental data on transient events in UV and Red-IR ranges obtained in the MSU missions "Unversitetsky-Tatiana" (wavelengths 300-400 nm) and "Unversitetsky-Tatiana-2" (wavelengths 300-400 nm and 600-800 nm), published by Garipov et al, in 2010 at COSPAR session http://www.cospar2010.org, at TEPA conference http://www.aragats.am/Conferences/tepa2010 and in 2011 by Sadovnichy et al, Solar System Research, 45, #1, 3-29 (2011); Vedenkin et al, JETP, v. 140, issue 3(9), 1-11 (2011) demonstrated existence of transients at large distances (up to thousands km) away of cloud thunderstorm regions. Those "remote" transients are short (1-5 msec) and are less luminous than the transients above thunderstorm regions. The ratio of Red-IR to UV photon numbers in those transients indicates high altitude of their origin (~70 km). Important observation facts are also: 1. a change of the exponent in transient distribution on luminosity Q ("-1" for photon numbers Q=1020 -1023 to "-2" for Q>1023), 2. a change of global distribution of transient with their luminosity (transients with Q>1023 are concentrated in equatorial range above continents, while transients with low luminosity are distributed more uniformly), 3. a phenomenon of transient sequences in one satellite orbit which is close to geomagnetic meridian. In the present paper phenomenological features of transients are explained in assumption that the observed transients have to be divided in two classes: 1. transients related to local, lower in the atmosphere, lightning at distance not more than hundreds km from satellite detector field of view in the atmosphere and 2. transients generated by far away lightning. Local transients are luminous and presumably are events called "transient luminous events" (TLE). In distribution on luminosity those events have some threshold Q~1023 and their differential luminosity distribution is approximated by power law exponent "-2". Remote transients have to be considered separately. Their origin may be related to electromagnetic pulses (EMP) or waves (whistler, EMW) generated by lightning. The EMP-EMW is transmitted in the ionosphere- ground channel to large distances R with low absorption. The part of EMP-EMW "visible" in the detector aperture diminishes with distance as R-1 due to observation geometry. The EMP-EMW triggers the electric discharge in the upper atmosphere (lower ionosphere, ~70 km). Estimates of resulting transients luminosity and their correlation with geomagnetic field are in progress.

  2. An Investigation on the role of Planetary Boundary Layer Parameterization scheme on the performance of a hydrostatic atmospheric model over a Coastal Region

    NASA Astrophysics Data System (ADS)

    Anurose, J. T.; Subrahamanyam, Bala D.

    2012-07-01

    As part of the ocean/land-atmosphere interaction, more than half of the total kinetic energy is lost within the lowest part of atmosphere, often referred to as the planetary boundary layer (PBL). A comprehensive understanding of the energetics of this layer and turbulent processes responsible for dissipation of kinetic energy within the PBL require accurate estimation of sensible and latent heat flux and momentum flux. In numerical weather prediction (NWP) models, these quantities are estimated through different surface-layer and PBL parameterization schemes. This research article investigates different factors influencing the accuracy of a surface-layer parameterization scheme used in a hydrostatic high-resolution regional model (HRM) in the estimation of surface-layer turbulent fluxes of heat, moisture and momentum over the coastal regions of the Indian sub-continent. Results obtained from this sensitivity study of a parameterization scheme in HRM revealed the role of surface roughness length (z_{0}) in conjunction with the temperature difference between the underlying ground surface and atmosphere above (?T = T_{G} - T_{A}) in the estimated values of fluxes. For grid points over the land surface where z_{0} is treated as a constant throughout the model integration time, ?T showed relative dominance in the estimation of sensible heat flux. In contrast to this, estimation of sensible and latent heat flux over ocean were found to be equally sensitive on the method adopted for assigning the values of z_{0} and also on the magnitudes of ?T.

  3. Socioeconomic Influences on Benzodiazepine Consumption in an Irish Region

    Microsoft Academic Search

    P. Quigley; C. Usher; K. Bennett; J. Feely

    2006-01-01

    Misuse of prescription sedatives is a significant problem for addiction treatment services. The aim of this study was to examine the prescribing of diazepam in disadvantaged Irish communities, and to identify factors which may predict diazepam consumption in that population. We examined prescribing trends for those aged 16–69 years in 2002 in a region of the state-funded General Medical Services

  4. Influence of projected snow and sea-ice changes on future climate in heavy snowfall region

    NASA Astrophysics Data System (ADS)

    Matsumura, S.; Sato, T.

    2011-12-01

    Snow/ice albedo and cloud feedbacks are critical for climate change projection in cryosphere regions. However, future snow and sea-ice distributions are significantly different in each GCM. Thus, surface albedo in cryosphere regions is one of the causes of the uncertainty for climate change projection. Northern Japan is one of the heaviest snowfall regions in the world. In particular, Hokkaido is bounded on the north by the Okhotsk Sea, where is the southernmost ocean in the Northern Hemisphere that is covered with sea ice during winter. Wintertime climate around Hokkaido is highly sensitive to fluctuations in snow and sea-ice. The purpose of this study is to evaluate the influence of global warming on future climate around Hokkaido, using the Pseudo-Global-Warming method (PGW) by a regional climate model. The boundary conditions of the PGW run were obtained by adding the difference between the future (2090s) and past (1990s) climates simulated by coupled general circulation model (MIROC3.2 medres), which is from the CMIP3 multi-model dataset, into the 6-hourly NCEP reanalysis (R-2) and daily OISST data in the past climate (CTL) run. The PGW experiments show that snow depth significantly decreases over mountainous areas and snow cover mainly decreases over plain areas, contributing to higher surface warming due to the decreased snow albedo. Despite the snow reductions, precipitation mainly increases over the mountainous areas because of enhanced water vapor content. However, precipitation decreases over the Japan Sea and the coastal areas, indicating the weakening of a convergent cloud band, which is formed by convergence between cold northwesteries from the Eurasian continent and anticyclonic circulation over the Okhotsk Sea. These results suggest that Okhotsk sea-ice decline may change the atmospheric circulation and the resulting effect on cloud formation, resulting in changes in winter snow or precipitation. We will also examine another CMIP3 model (MRI-CGCM2.3.2), which sensitivity of surface albedo to surface air temperature is the lowest in the CMIP3 models.

  5. Magnetosphere-Ionosphere Coupling in the Region of Electron Diffuse Aurora: The Role of Multiple Atmospheric Reflections

    NASA Astrophysics Data System (ADS)

    Himwich, E. W.; Khazanov, G. V.

    2014-12-01

    In the diffuse aurora, precipitating electrons initially injected from the plasmasheet via wave-particle interaction processes degrade in the atmosphere toward lower energies and produce secondary electrons via impact ionization of the neutral atmosphere. These precipitating electrons can be additionally reflected back into the magnetosphere by the conjugate atmospheres, leading to a series of multiple reflections that can greatly influence precipitating flux at the upper ionospheric boundary (700-800 km) and the resultant secondary electron population. We present the solution of the Boltzmann-Landau kinetic equation that uniformly describes the entire electron distribution function in the diffuse aurora, including the affiliated production of secondary electrons (E < 600 eV). This solution takes into account, for the first time, the role of multiple atmospheric reflections of the precipitated electrons that initially were moved into the loss cone via wave-particle interaction processes in the Earth's plasmasheet.

  6. About the Influence of the initial Atmosphere on the Earth's Temperature Distribution during it's Accumulation

    NASA Astrophysics Data System (ADS)

    Khachay, Y.; Anfilogov, V.; Antipin, A.

    2012-04-01

    We suggested a new model for accumulation of planets of the Earth's group [1], which is based on the contemporary results of geochemical analyses, which allow to obtain the concentrations of short living radioactive isotopes of 26Al in the matter of the pre planet cloud [2]. With use of that data new estimations of temperature distribution into the growing planetary pre planetary bodies into the Earth's nebular zone had been obtained. For the further Earth's temperature evolution, as it had been showed by the results of numerical modeling, the main role belongs to the temperature distribution in the forming Earth's core and the existence of a dense and transparent atmosphere. The shadow influence of the initial atmosphere had been researched in the paper [3]. We shall give the main consideration to these problems in that paper. It had been shown in [1], that on the earliest accumulation stage the heat release by the decay of 26Al it is sufficient for forming a central melted area and solid relatively thin mainly silicate upper envelope in the pre planetary body, with dimensions, larger than (50-100) km. The impact velocities on that stage are yet not large, therefore by the bodies impact with these or near dimensions liquid and mainly iron their parts merge, but the masses of the pre planetary bodies are not sufficient to gravitational keeping of silicate parts of the cold solid envelope. On that stage they remain into the nebular zone of the proto planet and the mechanism of matter differentiation for the future core and mantle reservoirs realizes. The process takes place yet in small bodies and is in time to finish during less than 10 million years. The next forming of the core and mantle structure continues according to all known estimations about 100 million years. Because of the merging of inner liquid parts of impacting bodies occur due to inelastic impact, the main part of potential energy transforms into heat. That continues up to that time when the iron core mass increases to the main part of the contemporary mass. The silicate particles of different dimensions remain in the proto planet cloud and in the initial atmosphere, reducing it's transparency and release of the heat radiation. On the finishing stage of the core growing the mass of the pre planetary body is sufficient for keeping of the rising part of the silicate envelope of falling bodies. The matter of the growing planet enriches more and more with a touch of silicates. The impact process of accumulated bodies gradually converts to the mechanism of elastic impact, by which only a small part of kinetic energy transforms into the merging by the pre planet body heat. The atmosphere losses the silicate particles and it's transparency exceeds. It is forming either a non melted mantle, or a mantle with a rising melted layer. That results show that the existence of a dense, nontransparent atmosphere leads to temperature growing in the inner areas of the planet during it's accumulation process. 1.Anfilogov V.N., Khachay Yu.V. A possible variant of matter differentiation on the initial stage of Earth's forming. // DAN. 2005, V. 403, N. 6, 803-806. 2.Merk R.,Breuer D., Spohn T., 2002. Numerical modeling of 26Al - Induced radioactive melting of asteroids concerning accretion, Icarus, 159, 183-191. 3.Hayashi C., Nakazawa K., Mizuno H. Earth's melting due to the blanketing effect of primordial dense atmosphere. // Earth and Plenetary Science Letters. (1979). v. 43, 22-28

  7. Influence of sedimentation, local and regional hydrothermal circulation, and thermal rebound on measurements

    E-print Network

    Fisher, Andrew

    Influence of sedimentation, local and regional hydrothermal circulation, and thermal rebound seepage through sediments each influence seafloor heat flux by 2­8%. Conductive thermal rebound following several to several tens of million years. The new models indicate that thermal rebound takes much longer

  8. The solar wind interaction with Mars: Recent progress and future directions The Sun has a powerful influence on planetary atmospheres.

    E-print Network

    California at Berkeley, University of

    Editorial The solar wind interaction with Mars: Recent progress and future directions The Sun has a powerful influence on planetary atmospheres. This is especially true for planets lacking a global magnetic field, because the solar wind can interact directly with the upper atmo- sphere. Neutral particles

  9. Northern Hemisphere atmospheric influence of the solar proton events and ground level enhancement in January 2005

    NASA Astrophysics Data System (ADS)

    Jackman, C. H.; Marsh, D. R.; Vitt, F. M.; Roble, R. G.; Randall, C. E.; Bernath, P. F.; Funke, B.; López-Puertas, M.; Versick, S.; Stiller, G. P.; Tylka, A. J.; Fleming, E. L.

    2011-03-01

    Solar eruptions in early 2005 led to a substantial barrage of charged particles on the Earth's atmosphere during the 16-21 January period. Proton fluxes were greatly increased during these several days and led to the production of HOx (H, OH, HO2) and NOx (N, NO, NO2), which then caused the destruction of ozone. We focus on the Northern polar region, where satellite measurements and simulations with the Whole Atmosphere Community Climate Model (WACCM3) showed large enhancements in mesospheric HOx and NOx constituents, and associated ozone reductions, due to these solar proton events (SPEs). The WACCM3 simulations show enhanced short-lived OH throughout the mesosphere in the 60-82.5° N latitude band due to the SPEs for most days in the 16-21 January 2005 period, in reasonable agreement with the Aura Microwave Limb Sounder (MLS) measurements. Mesospheric HO2 is also predicted to be increased by the SPEs, however, the modeled HO2 results are somewhat larger than the MLS measurements. These HOx enhancements led to huge predicted and MLS-measured ozone decreases of greater than 40% throughout most of the northern polar mesosphere during the SPE period. Envisat Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) measurements of hydrogen peroxide (H2O2) show increases throughout the stratosphere with highest enhancements of about 60 pptv in the lowermost mesosphere over the 16-18 January 2005 period due to the solar protons. WACCM3 predictions indicate H2O2 enhancements over the same time period of more than twice that amount. Measurements of nitric acid (HNO3) by both MLS and MIPAS show an increase of about 1 ppbv above background levels in the upper stratosphere during 16-29 January 2005. WACCM3 simulations show only minuscule HNO3 changes in the upper stratosphere during this time period. Polar mesospheric enhancements of NOx are computed to be greater than 50 ppbv during the SPE period due to the small loss rates during winter. Computed NOx increases, which were statistically significant at the 95% level, lasted about a month past the SPEs. The SCISAT-1 Atmospheric Chemistry Experiment Fourier Transform Spectrometer NOx measurements and MIPAS NO2 measurements for the polar Northern Hemisphere are in reasonable agreement with these predictions. An extremely large ground level enhancement (GLE) occurred during the SPE period on 20 January 2005. We find that protons of energies 300 to 20 000 MeV, not normally included in our computations, led to enhanced lower stratospheric odd nitrogen concentrations of less than 0.1% as a result of this GLE.

  10. Northern Hemisphere atmospheric influence of the solar proton events and ground level enhancement in January 2005

    NASA Astrophysics Data System (ADS)

    Jackman, C. H.; Marsh, D. R.; Vitt, F. M.; Roble, R. G.; Randall, C. E.; Bernath, P. F.; Funke, B.; López-Puertas, M.; Versick, S.; Stiller, G. P.; Tylka, A. J.; Fleming, E. L.

    2011-07-01

    Solar eruptions in early 2005 led to a substantial barrage of charged particles on the Earth's atmosphere during the 16-21 January period. Proton fluxes were greatly increased during these several days and led to the production of HOx (H, OH, HO2) and NOx (N, NO, NO2), which then caused the destruction of ozone. We focus on the Northern polar region, where satellite measurements and simulations with the Whole Atmosphere Community Climate Model (WACCM3) showed large enhancements in mesospheric HOx and NOx constituents, and associated ozone reductions, due to these solar proton events (SPEs). The WACCM3 simulations show enhanced short-lived OH and HO2 concentrations throughout the mesosphere in the 60-82.5° N latitude band due to the SPEs for most days in the 16-21 January 2005 period, somewhat higher in abundance than those observed by the Aura Microwave Limb Sounder (MLS). These HOx enhancements led to huge predicted and MLS-measured ozone decreases of greater than 40 % throughout most of the northern polar mesosphere during the SPE period. Envisat Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) measurements of hydrogen peroxide (H2O2) show increases throughout the stratosphere with highest enhancements of about 60 pptv in the lowermost mesosphere over the 16-18 January 2005 period due to the solar protons. WACCM3 predictions indicate H2O2 enhancements over the same time period of about three times that amount. Measurements of nitric acid (HNO3) by both MLS and MIPAS show an increase of about 1 ppbv above background levels in the upper stratosphere during 16-29 January 2005. WACCM3 simulations show only minuscule HNO3 increases (<0.05 ppbv) in the upper stratosphere during this time period. Polar mesospheric enhancements of NOx are computed to be greater than 50 ppbv during the SPE period due to the small loss rates during winter. Computed NOx increases, which were statistically significant at the 95 % level, lasted about a month past the SPEs. The SCISAT-1 Atmospheric Chemistry Experiment Fourier Transform Spectrometer NOx measurements and MIPAS NO2 measurements for the polar Northern Hemisphere are in reasonable agreement with these predictions. An extremely large ground level enhancement (GLE) occurred during the SPE period on 20 January 2005. We find that protons of energies 300 to 20 000 MeV, associated with this GLE, led to very small enhanced lower stratospheric odd nitrogen concentrations of less than 0.1 % and ozone decreases of less than 0.01 %.

  11. Shape of atmospheric mineral particles collected in three Chinese arid-regions

    NASA Astrophysics Data System (ADS)

    Okada, Kikuo; Heintzenberg, Jost; Kai, Kenji; Qin, Yu

    The shape of atmospheric mineral particles of 0.1-6 µm radius was studied by electron microscopy applied to the samples collected in three arid regions in China (Qira in the Taklamakan Desert, Zhangye near the southern border of the Badain-Jaran Desert and Hohhot in northern China). In all three regions, the mineral particles showed irregular shapes with a median aspect ratio b/a (ratio of the longest dimension b to the orthogonal width a) of 1.4. Although the aspect ratio exhibited no clear size dependence, the circularity factor (4?S/l² S is surface area and l is periphery length) tended to decrease with increasing radius, suggesting the presence of aggregated mineral particles at larger sizes. The ratio of particle height-to-width h/a was also evaluated by measuring the shadow length. The median ratio h/a was 0.49 in Hohhot, 0.29 in Zhangye and 0.23 in Qira. Analytical functions were fitted to the grand total of the frequency distributions of aspect ratios, height-to-width ratios and circularity factors allowing parametric calculations of radiative effects and calculations of optical and sedimentation behavior of mineral particles.

  12. Development and validation of a regional coupled atmosphere lake model for the Caspian Sea Basin

    NASA Astrophysics Data System (ADS)

    Turuncoglu, Ufuk Utku; Elguindi, Nellie; Giorgi, Filippo; Fournier, Nicolas; Giuliani, Graziano

    2013-10-01

    We present a validation analysis of a regional climate model coupled to a distributed one dimensional (1D) lake model for the Caspian Sea Basin. Two model grid spacings are tested, 50 and 20 km, the simulation period is 1989-2008 and the lateral boundary conditions are from the ERA-Interim reanalysis of observations. The model is validated against atmospheric as well as lake variables. The model performance in reproducing precipitation and temperature mean seasonal climatology, seasonal cycles and interannual variability is generally good, with the model results being mostly within the observational uncertainty range. The model appears to overestimate cloudiness and underestimate surface radiation, although a large observational uncertainty is found in these variables. The 1D distributed lake model (run at each grid point of the lake area) reproduces the observed lake-average sea surface temperature (SST), although differences compared to observations are found in the spatial structure of the SST, most likely as a result of the absence of 3 dimensional lake water circulations. The evolution of lake ice cover and near surface wind over the lake area is also reproduced by the model reasonably well. Improvements resulting from the increase of resolution from 50 to 20 km are most significant in the lake model. Overall the performance of the coupled regional climate—1D lake model system appears to be of sufficient quality for application to climate change scenario simulations over the Caspian Sea Basin.

  13. Regional and large-scale influences on seasonal to interdecadal variability in Caribbean surface air temperature in CMIP5 simulations

    NASA Astrophysics Data System (ADS)

    Ryu, Jung-Hee; Hayhoe, Katharine

    2015-07-01

    We evaluate the ability of global climate models participating in phase 5 of the Coupled Model Intercomparison Project (CMIP5) to reproduce observed seasonality and interannual variability of temperature over the Caribbean, and compare these with simulations from atmosphere-only (AMIP5) and previous-generation CMIP3 models. Compared to station and gridded observations, nearly every CMIP5, CMIP3 and AMIP5 simulation tends to reproduce the primary inter-regional features of the Caribbean annual temperature cycle. In most coupled model simulations, however, boreal summer temperature lags observations by about 1 month, with a similar lag in the simulated annual cycle of sea surface temperature (SST), and a systematic cold bias in both climatological annual mean air temperature and SST. There is some improvement from CMIP3 to CMIP5 but the bias is still marked compared to AMIP5 and observations, implying that biases in the annual temperature cycle may originate in the ocean component of the coupled models. This also suggests a tendency for models to over-emphasize the influence of SSTs on near-surface temperature, a bias that may be exacerbated by model tendency to over-estimate ocean mixed layer depth as well. In contrast, we find that both coupled and atmosphere-only models tend to reasonably simulate the response of observed temperature to global temperature, to regional and large-scale variability across the Caribbean region and the Gulf of Mexico, and even to more remote Atlantic and Pacific influences. These findings contribute to building confidence in the ability of coupled models to simulate the effect of global-scale change on the Caribbean.

  14. Atmospheric effects and societal consequences of regional scale nuclear conflicts and acts of individual nuclear terrorism

    NASA Astrophysics Data System (ADS)

    Toon, O. B.; Turco, R. P.; Robock, A.; Bardeen, C.; Oman, L.; Stenchikov, G. L.

    2006-11-01

    We assess the potential damage and smoke production associated with the detonation of small nuclear weapons in modern megacities. While the number of nuclear warheads in the world has fallen by about a factor of three since its peak in 1986, the number of nuclear weapons states is increasing and the potential exists for numerous regional nuclear arms races. Eight countries are known to have nuclear weapons, 2 are constructing them, and an additional 32 nations already have the fissile material needed to build substantial arsenals of low-yield (Hiroshima-sized) explosives. Population and economic activity worldwide are congregated to an increasing extent in megacities, which might be targeted in a nuclear conflict. Our analysis shows that, per kiloton of yield, low yield weapons can produce 100 times as many fatalities and 100 times as much smoke from fires as high-yield weapons, if they are targeted at city centers. A single "small'' nuclear detonation in an urban center could lead to more fatalities, in some cases by orders of magnitude, than have occurred in the major historical conflicts of many countries. We analyze the likely outcome of a regional nuclear exchange involving 100 15-kt explosions (less than 0.1% of the explosive yield of the current global nuclear arsenal). We find that such an exchange could produce direct fatalities comparable to all of those worldwide in World War II, or to those once estimated for a "counterforce'' nuclear war between the superpowers. Megacities exposed to atmospheric fallout of long-lived radionuclides would likely be abandoned indefinitely, with severe national and international implications. Our analysis shows that smoke from urban firestorms in a regional war would rise into the upper troposphere due to pyro-convection. Robock et al. (2006) show that the smoke would subsequently rise deep into the stratosphere due to atmospheric heating, and then might induce significant climatic anomalies on global scales.We also anticipate substantial perturbations of global ozone. While there are many uncertainties in the predictions we make here, the principal unknowns are the type and scale of conflict that might occur. The scope and severity of the hazards identified pose a significant threat to the global community. They deserve careful analysis by governments worldwide advised by a broad section of the world scientific community, as well as widespread public debate.

  15. Atmospheres

    NASA Astrophysics Data System (ADS)

    Bott, June; Yin, Hongbin; Sridhar, Seetharaman

    2014-12-01

    When high Al containing Fe alloys such as TRIP steels are exposed to atmospheres that contain N2 during re-heating, sub-surface nitrides form and these can be detrimental to mechanical properties. Nitride precipitation can be controlled by minimizing the access of the gaseous atmosphere to the metal surface, which can be achieved by a rapid growth of a continuous and adherent surface scale. This investigation utilizes a Au-image furnace attached to a confocal scanning microscope to simulate the annealing temperature vs time while Fe-Al alloys (with Al contents varying from 1 to 8 wt pct) are exposed to a O2-N2 atm with 10-6 atm O2. The heating times of 1, 10, and 100 minutes to the isothermal temperature of 1558 K (1285 °C) were used. It was found that fewer sub-surface nitride precipitates formed when the heating time was lowered and when Al content in the samples was increased. In the 8 wt pct samples, no internal nitride precipitates were present regardless of heating time. In the 3 and 5 wt pct samples, internal nitride precipitates were nearly more or less absent at heating times less than 10 minutes. The decrease in internal precipitates was governed by the evolving structure of the external oxide-scale. At low heating rates and/or low Al contents, significant Fe-oxide patches formed and these appeared to allow for ingress of gaseous N2. For the slow heating rates, ingress could have happened during the longer time spent in lower temperatures where non-protective alumina was present. As Al content in the alloy was increased, the external scale was Al2O3 and/or FeAl2O4 and more continuous and consequently hindered the N2 from accessing the metal surface. Increasing the Al content in the alloy had the effect of promoting the outward diffusion of Al in the alloy and thereby assisting the formation of the continuous external layer of Al2O3 and/or FeAl2O4.

  16. Multivariate weather prediction with atmospheric analogs: predictors and probabilistic prediction skill for different European regions

    NASA Astrophysics Data System (ADS)

    Raynaud, Damien; Hingray, Benoit; Chardon, Jeremy; Anquetin, Sandrine; Favre, Anne-Catherine; François, Baptiste; Vautard, Robert; Tobin, Isabelle

    2015-04-01

    Among the usual methodologies of dynamical or statistical downscaling of climate model, the Analog method appears to be one of the simplest regarding its conceptual nature and its computational costs (Lorentz, 1969). It assumes strong relationships between large scale meteorological variables (predictors) and local weather variables (predictants) so that for two similar large scale situations, the regional consequences on local weather are supposed to be identical. Despite its simplicity, its skill for local scale and/or regional scale prediction is often reported to be very satisfactory. The Analog method has been widely used in Europe to produce precipitation and temperature predictions. For an increasing number of impact studies (e.g. hydrological ones), weather scenarios have to be multivariate and must include additional variables such as wind or radiation. The development of relevant multivariate weather series is however challenging. Weather scenarios have especially to be physically consistent between all weather variables. This issue, which may be critical when relevant hydrological scenarios have to be produced, was to our knowledge fairly not explored. The Analog method has the ability to easily tackle this problem selecting the same analog date for all the weather predictants and thus insuring automatically the physical consistency. However, the best analogs of a given simulation day are likely to depend on the predictant considered. Achieving physical consistency between variables, which implies optimizing the method in a multivariate approach, therefore a priori requires finding a compromise between the different predictors which would be the best for the different predictant taken separately. For the present study, we use a stepwise Analog method for the probabilistic prediction of regional precipitation, temperature, wind and solar radiation. We explore for 12 regions across Europe the variability and diversity of the most skillful parameterisation of the method in terms of predictors (variable, atmospheric level, shape and size of the geographical domain used for the analogs identification). Predictors are extracted from ERA-Interim reanalyses. Predictants are obtained from the European Climate Assessment and Dataset for precipitation and temperature and derived from high resolution Weather Research and Forecasting model simulations (Tobin et al., 2014) for wind and solar radiation pseudo-observations. We evaluate the method's ability to correctly reproduce the recent past climate of the regions and we discuss how the results vary depending on the target region. We also discuss for each predictant the loss of prediction performances due to the multivariate approach compared to the usual univariate one. Lorenz, E. N., (1969) Atmospheric predictability as revealed by naturally occurring analogues. J. Atmos. Sci., 26, 636-646. Tobin, I., Vautard, R., Balog, I., Bréon, F. M., Jerez, S., Ruti, P. M., ... & Yiou, P. (2014). Assessing climate change impacts on European wind energy from ENSEMBLES high-resolution climate projections. Climatic Change, 1-14.

  17. Autofluorescence of atmospheric bioaerosols - Biological standard particles and the influence of environmental conditions

    NASA Astrophysics Data System (ADS)

    Pöhlker, Christopher; Huffman, J. Alex; Förster, Jan-David; Pöschl, Ulrich

    2013-04-01

    Primary biological aerosol particles (PBAP) such as pollen, fungal spores, bacteria, biogenic polymers and debris from larger organisms are known to influence atmospheric chemistry and physics, the biosphere and public health. PBAP can account for up to ~30% of fine and up to ~70% of coarse particulate matter in urban, rural and pristine environment and are released with estimated emission rates of up to ~1000 Tg/a [1]. Continuous measurements of the abundance, variability and diversity of PBAP have been difficult until recently, however. The application of on-line instruments able to detect autofluorescence from biological particles in real-time has been a promising development for the measurement of PBAP concentrations and fluxes in different environments [2,3]. The detected fluorescent biological aerosol particles (FBAP) can be regarded as a subset of PBAP, although the exact relationship between PBAP and FBAP is still being investigated. Autofluorescence of FBAP is usually a superposition of fluorescence from a mixture of individual fluorescent molecules (fluorophores). Numerous biogenic fluorophores such as amino acids (e.g., tryptophan, tyrosine), coenzymes (e.g., NAD(P)H, riboflavin) and biopolymers (e.g., cellulose) emit fluorescent light due to heterocyclic aromatic rings or conjugated double bonds within their molecular structures. The tryptophan emission peak is a common feature of most bioparticles because the amino acid is a constituent of many proteins and peptides. The influence of the coenzymes NAD(P)H and riboflavin on the autofluorescence of bacteria can be regarded as an indicator for bacterial metabolism and has been utilized to discriminate between viable and non-viable organisms [4]. However, very little information is available about other essential biofluorophores in fungal spores and pollen. In order to better understand the autofluorescence behavior of FBAP, we have used fluorescence spectroscopy and fluorescence microscopy to analyze standard bioparticles (pollen, fungal spores, and bacteria) as well as atmospherically relevant chemical substances. We addressed the sensitivity and selectivity of autofluorescence based online techniques. Moreover, we investigated the influence of environmental conditions, such as relative humidity and oxidizing agents in the atmosphere, on the autofluorescence signature of standard bioparticles. Our results will support the molecular understanding and quantitative interpretation of data obtained by real-time FBAP instrumentation [5,6]. [1] Elbert, W., Taylor, P. E., Andreae, M. O., & Pöschl, U. (2007). Atmos. Chem. Phys., 7, 4569-4588. [2] Huffman, J. A., Treutlein, B., & Pöschl, U. (2010). Atmos. Chem. Phys., 10, 3215-3233. [3] Pöschl, U., et al. (2010). Science, 329, 1513-1516. [4] Lakowicz, J., Principles of fluorescence spectroscopy, Plenum publishers, New York, 1999. [5] Pöhlker, C., Huffman, J. A., & Pöschl, U., (2012). Atmos. Meas. Tech., 5, 37-71. [6] Pöhlker, C., Huffman, J. A., Förster J.-D., & Pöschl, U., (2012) in preparation.

  18. Recent surface mass balance from Syowa Station to Dome F, East Antarctica: comparison of field observations, atmospheric reanalyses, and a regional atmospheric climate model

    NASA Astrophysics Data System (ADS)

    Wang, Yetang; Hou, Shugui; Sun, Weijun; Lenaerts, Jan T. M.; van den Broeke, Michiel R.; van Wessem, J. M.

    2015-02-01

    Stake measurements at 2 km intervals are used to determine the spatial and temporal surface mass balance (SMB) in recent decades along the Japanese Antarctic Research Expedition traverse route from Syowa Station to Dome F. To determine SMB variability at regional scales, this traverse route is divided into four regions, i.e., coastal, lower katabatic, upper katabatic and inland plateau. We also perform a regional evaluation of large scale SMB simulated by the regional atmospheric climate model versions 2.1 and 2.3 (RACMO2.1 and RACMO2.3), and the four more recent global reanalyses. Large-scale spatial variability in the multi-year averaged SMB reveals robust relationships with continentality and surface elevation. In the katabatic regions, SMB variability is also highly associated with surface slope, which in turn is affected by bedrock topography. Stake observation records show large inter-annual variability in SMB, but did not indicate any significant trends over both the last 40 years for the coastal and lower katabatic regions, and the last 20 years record for the upper katabatic and inland plateau regions. The four reanalyses and the regional climate model reproduce the macro-scale spatial pattern well for the multi-year averaged SMB, but fail to capture the mesoscale SMB increase at the distance interval ~300 to ~400 km from Syowa station. Thanks to the updated scheme in the cloud microphysics, RACMO2.3 shows the best spatial agreement with stake measurements over the inland plateau region. ERA-interim, JRA-55 and MERRA exhibit high agreement with the inter-annual variability of observed SMB in the coastal, upper katabatic and inland plateau regions, and moderate agreement in the lower katabatic region, while NCEP2 and RACMO2.1 inter-annual variability shows no significant correlation with the observations for the inland plateau region.

  19. Influence of atmospheric vapour pressure deficit on ozone responses of snap bean (Phaseolus vulgaris L.) genotypes

    PubMed Central

    Fiscus, Edwin L.; Booker, Fitzgerald L.; Sadok, Walid; Burkey, Kent O.

    2012-01-01

    Environmental conditions influence plant responses to ozone (O3), but few studies have evaluated individual factors directly. In this study, the effect of O3 at high and low atmospheric vapour pressure deficit (VPD) was evaluated in two genotypes of snap bean (Phaseolus vulgaris L.) (R123 and S156) used as O3 bioindicator plants. Plants were grown in outdoor controlled-environment chambers in charcoal-filtered air containing 0 or 60 nl l?1 O3 (12 h average) at two VPDs (1.26 and 1.96 kPa) and sampled for biomass, leaf area, daily water loss, and seed yield. VPD clearly influenced O3 effects. At low VPD, O3 reduced biomass, leaf area, and seed yield substantially in both genotypes, while at high VPD, O3 had no significant effect on these components. In clean air, high VPD reduced biomass and yield by similar fractions in both genotypes compared with low VPD. Data suggest that a stomatal response to VPD per se may be lacking in both genotypes and it is hypothesized that the high VPD resulted in unsustainable transpiration and water deficits that resulted in reduced growth and yield. High VPD- and water-stress-induced stomatal responses may have reduced the O3 flux into the leaves, which contributed to a higher yield compared to the low VPD treatment in both genotypes. At low VPD, transpiration increased in the O3 treatment relative to the clean air treatment, suggesting that whole-plant conductance was increased by O3 exposure. Ozone-related biomass reductions at low VPD were proportionally higher in S156 than in R123, indicating that differential O3 sensitivity of these bioindicator plants remained evident when environmental conditions were conducive for O3 effects. Assessments of potential O3 impacts on vegetation should incorporate interacting factors such as VPD. PMID:22268148

  20. Pollution characterization and diurnal variation of PBDEs in the atmosphere of an E-waste dismantling region

    Microsoft Academic Search

    Duohong Chen; Xinhui Bi; Jinping Zhao; Laiguo Chen; Jihua Tan; Bixian Mai; Guoying Sheng; Jiamo Fu; Minghung Wong

    2009-01-01

    Diurnal air samples were collected from the E-waste dismantling region Guiyu and the underwear industry region Chendian. This was the first report to present the diurnal variation of PBDEs in the atmosphere. The average concentrations of 11 PBDE congeners were 11,742pgm?3 in the daytime, and 4830pgm?3 at night in Guiyu, while the concentrations were lower in Chendian with 376pgm?3 in

  1. Does wet precipitation represent local and regional atmospheric transportation by perfluorinated alkyl substances?

    PubMed

    Taniyasu, Sachi; Yamashita, Nobuyoshi; Moon, Hyo-Bang; Kwok, Karen Y; Lam, Paul K S; Horii, Yuichi; Petrick, Gert; Kannan, Kurunthachalam

    2013-05-01

    Perfluorinated alkyl substances (PFASs) have been found widely in the environment including remote marine locations. The mode of transport of PFASs to remote marine locations is a subject of considerable scientific interest. Assessment of distribution of PFASs in wet precipitation samples (i.e., rainfall and snow) collected over an area covering continental, coastal, and open ocean will enable an understanding of not only the global transport but also the regional transport of PFASs. Nevertheless, it is imperative to examine the representativeness and suitability of wet precipitation matrixes to allow for drawing conclusions on the transport PFASs. In this study, we collected wet precipitation samples including rainfall, surface snow, and snow core from several locations in Japan to elucidate the suitability of these matrixes for describing local and regional transport of PFASs. Rain water collected at various time intervals within a single rainfall event showed high fluxes of PFASs in the first 1-mm deposition. The scavenging rate of PFASs by wet deposition varied depending on the fluorocarbon chain length of PFAS. The depositional fluxes of PFASs measured for continental (Tsukuba, Japan) and open ocean (Pacific Ocean, 1000km off Japanese coast) locations were similar, on the order of a few nanograms per square meter. The PFAS profiles in "freshly" deposited and "aged" (deposited on the ground for a few days) snow samples taken from the same location varied considerably. The freshly deposited snow represents current atmospheric profiles of PFASs, whereas the aged snow sample reflects sequestration of local sources of PFASs from the atmosphere. Post-depositional modifications in PFAS profiles were evident, suggesting reactions of PFASs on snow/ice surface. Transformation of precursor chemicals such as fluorotelomer alcohols into perfluoroalkylcarboxylates is evident on snow surface. Snow cores have been used to evaluate time trends of PFAS contamination in remote environments. Snow collected at various depths from a core of up to 7.7m deep, at Mt. Tateyama (2450m), Japan, showed the highest concentrations of PFASs in the surface layer and the concentrations decreased with increasing depth for most PFASs, except for perfluorobutanesulfonate (PFBS). Downward movement of highly water soluble PFASs such as PFBS, following melting and freezing cycles of snow, was evident from the analysis of snow core. PMID:23506970

  2. Bioclimatic regions influence genetic structure of four Jordanian Stipa species.

    PubMed

    Hamasha, H R; Schmidt-Lebuhn, A N; Durka, W; Schleuning, M; Hensen, I

    2013-09-01

    Strong environmental gradients can affect the genetic structure of plant populations, but little is known as to whether closely related species respond similarly or idiosyncratically to ecogeographic variation. We analysed the extent to which gradients in temperature and rainfall shape the genetic structure of four Stipa species in four bioclimatic regions in Jordan. Genetic diversity, differentiation and structure of Stipa species were investigated using amplified fragment length polymorphism (AFLP) molecular markers. For each of the four study species, we sampled 120 individuals from ten populations situated in distinct bioclimatic regions and assessed the degree of genetic diversity and genetic differentiation within and among populations. The widespread ruderals Stipa capensis and S. parviflora had higher genetic diversity than the geographically restricted semi-desert species S. arabica and S. lagascae. In three of the four species, genetic diversity strongly decreased with precipitation, while genetic diversity increased with temperature in S. capensis. Most genetic diversity resided among populations in the semi-desert species (?(ST) = 0.572/0.595 in S. arabica/lagascae) but within populations in the ruderal species (?(ST) = 0.355/0.387 S. capensis/parviflora). Principal coordinate analysis (PCoA) and STRUCTURE analysis showed that Stipa populations of all species clustered ecogeographically. A genome scan revealed that divergent selection at particular AFLP loci contributed to genetic differentiation. Irrespective of their different life histories, Stipa species responded similarly to the bioclimatic gradient in Jordan. We conclude that, in addition to predominant random processes, steep climatic gradients might shape the genetic structure of plant populations. PMID:23369254

  3. Influence of aerosol chemical composition on N2O5 uptake: airborne regional measurements in northwestern Europe

    NASA Astrophysics Data System (ADS)

    Morgan, W. T.; Ouyang, B.; Allan, J. D.; Aruffo, E.; Di Carlo, P.; Kennedy, O. J.; Lowe, D.; Flynn, M. J.; Rosenberg, P. D.; Williams, P. I.; Jones, R.; McFiggans, G. B.; Coe, H.

    2015-01-01

    Aerosol chemical composition was found to influence nighttime atmospheric chemistry during a series of airborne measurements in northwestern Europe in summer conditions, which has implications for regional air quality and climate. The uptake of dinitrogen pentoxide, ? (N2O5), to particle surfaces was found to be modulated by the amount of water content and ammonium nitrate present in the aerosol. The conditions prevalent in this study suggest that the net uptake rate of N2O5 to atmospheric aerosols was relatively efficient compared to previous studies, with ? (N2O5) values in the range 0.01-0.03. This is likely a consequence of the elevated relative humidity in the region, which promotes greater aerosol water content. Increased nitrate concentrations relative to particulate water were found to suppress N2O5 uptake. The results presented here contrast with previous ambient studies of N2O5 uptake, which have generally taken place in low-nitrate environments in the USA. Comparison of the N2O5 uptake derived from the measurements with a parameterised scheme that is based on the ratio of particulate water to nitrate yielded reasonably good agreement in terms of the magnitude and variation in uptake, provided the effect of chloride was neglected. An additional suppression of the parameterised uptake is likely required to fully capture the variation in N2O5 uptake, which could be achieved via the known suppression by organic aerosol. However, existing parameterisations representing the suppression by organic aerosol were unable to fully represent the variation in N2O5 uptake. These results provide important ambient measurement constraint on our ability to predict N2O5 uptake in regional and global aerosol models. N2O5 uptake is a potentially important source of nitrate aerosol and a sink of the nitrate radical, which is the main nocturnal oxidant in the atmosphere. The results further highlight the importance of ammonium nitrate in northwestern Europe as a key component of atmospheric composition in the region.

  4. Assessing Predictability of Cotton Yields in the Southeastern United States Based on Regional Atmospheric Circulation and Surface Temperatures

    Microsoft Academic Search

    Guillermo A. Baigorria; James W. Hansen; Neil Ward; James W. Jones; James J. O’Brien

    2008-01-01

    The potential to predict cotton yields up to one month before planting in the southeastern United States is assessed in this research. To do this, regional atmospheric variables that are related to historic summer rainfall and cotton yields were identified. The use of simulations of those variables from a global circulation model (GCM) for estimating cotton yields was evaluated. The

  5. Journal of Atmospheric and Solar-Terrestrial Physics 68 (2006) 10611074 Seasonal variation of mesopause region wind shears,

    E-print Network

    2006-01-01

    Journal of Atmospheric and Solar-Terrestrial Physics 68 (2006) 1061­1074 Seasonal variation of mesopause region wind shears, convective and dynamic instabilities above Fort Collins, CO: A statistical) temperature and horizontal wind, observed by Colorado State University sodium lidar over Fort Collins, CO (411

  6. Atmospheric inputs of phosphorus and nitrogen to the southwest Mediterranean region: Biogeochemical responses of high mountain lakes

    Microsoft Academic Search

    Rafael Morales-Baquero; Elvira Pulido-Villena; Isabel Reche

    2006-01-01

    We quantified dry and wet deposition of dust, nitrogen, and phosphorus over the southwest Mediterranean region (Sierra Nevada, Spain) and assessed its effects on the nutrient status and the chlorophyll a (Chl a) concentration in two high mountain lakes. Atmospheric deposition of particulate matter (PM) and total phosphorus (TP) were mainly associated with dryfall and showed a seasonal pattern similar

  7. A regional scale modeling study of atmospheric transport and transformation of mercury. II. Simulation results for the northeast United States

    Microsoft Academic Search

    Xiaohong Xu; Xiusheng Yang; David R Miller; Joseph J Helble; Robert J Carley

    2000-01-01

    This paper presents the results of a simulation study of the transport, transformation, and deposition of atmospheric mercury (Hg) in the northeastern United States for 5 consecutive days in summer 1997, using the newly developed regional scale air quality model described in part I. Hourly ambient concentrations, in-cloud transformations, and deposition fluxes were predicted for each of the three mercury

  8. The influence of plants on atmospheric methane in an agriculture-dominated landscape.

    PubMed

    Zhang, Xin; Lee, Xuhui; Griffis, Timothy J; Baker, John M; Erickson, Matt D; Hu, Ning; Xiao, Wei

    2014-07-01

    The primary objective of this study was to clarify the influence of crop plants on atmospheric methane (CH4) in an agriculture-dominated landscape in the Upper Midwest of the United States. Measurements were carried out at two contrasting scales. At the plant scale, CH4 fluxes from soybean and corn plants were measured with a laser-based plant chamber system. At the landscape scale, the land surface flux was estimated with a modified Bowen ratio technique using measurements made on a tall tower. The chamber data revealed a diurnal pattern for the plant CH4 flux: it was positive (an emission rate of 0.4±0.1 nmol m(-2) s(-1), average of soybean and corn, in reference to the unit ground area) during the day, and negative (an uptake rate of -0.8±0.8 nmol m(-2) s(-1)) during the night. At the landscape scale, the flux was estimated to be 14.8 nmol m(-2) s(-1) at night and highly uncertain during the day, but the available references and the flux estimates from the equilibrium methods suggested that the CH4 flux during the entire observation period was similar to the estimated nighttime flux. Thus, soybean and corn plants have a negligible role in the landscape-scale CH4 budget. PMID:23612798

  9. Influence of outgassing on plasma kinetics during wood treatment in dielectric barrier discharges at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Gangwar, R.; Levasseur, O.; Stafford, L.; Naude, N.; Gherardi, N.; Univ. de Montreal Team

    2013-09-01

    We have recently extended the range of applications of dielectric barrier discharges (DBD) at atmospheric pressure to the functionalization of wood surfaces with the objective of improving its durability following natural weathering. Having highly complex chemical composition and microstructure, it can release significant amount of impurities, which can play a crucial role on the plasma kinetics, and therefore on the process dynamics. The influence of wood outgassing on the physics driving DBD operated in nominally pure He was investigated using a combination of time-resolved optical emission spectroscopy (OES) and collisional-radiative (CR) modeling. For completely outgassed samples, the He I 588 nm-to-707 nm and 668 nm-to-728 nm line intensity ratios were relatively high early in the discharge cycle, decreased abruptly and then remained stable as the current increased and the discharge eventually extinguished. These results were correlated to a decrease of the electron temperature from about 1 eV early in the cycle to about 0.2 eV in the main discharge lifetime. As wood outgassing evolve, study revealed that the release of products (essentially air) from the wood substrate yields to an increase of the cycle-averaged electron temperature as well as to a significant quenching of He metastable atoms. Selected experiments in presence of trace amounts of N2, O2 and dry-air were also performed to better understand their respective roles.

  10. Study on the Microsecond Pulse Homogeneous Dielectric Barrier Discharges in Atmospheric Air and Its Influencing Factors

    NASA Astrophysics Data System (ADS)

    Fang, Zhi; Lei, Xiao; Cai, Lingling; Qiu, Yuchang; Edmund, Kuffel

    2011-12-01

    The homogeneous dielectric barrier discharge (DBD) in atmospheric air between two symmetric-columnar copper electrodes with epoxy plates as the dielectric barriers is generated using a ?s pulse high voltage power supply. The discharge characteristics are studied by measurement of its electrical discharge parameters and observation of its light emission phenomena, and the main discharge parameters of the homogenous DBD, such as discharge current and average discharge power, are calculated. Results show that the discharge generated is a homogeneous one with one larger single current pulse of about 2 ?s duration appearing in each voltage pulse, and its light emission is radially homogeneous and covers the entire surface of the two electrodes. The influences of applied voltage amplitude, air gap distance and barrier thickness on the transition of discharge modes are studied. With the increase of air gap distance, the discharge will transit from homogeneous mode to filamentary mode. The higher the thickness of dielectric barriers, the larger the air gap distance for generating the homogeneous discharge mode. The average discharge power increases non-linearly with increasing applied voltage amplitude, and decreases non-linearly with the increase of air gap distance and barrier thickness. In order to generate stable and homogeneous DBD with high discharge power, thin barriers distance should be used, and higher applied voltage amplitude should be applied to small air gap.

  11. Atmospheric influences on water quality: a simulation of nutrient loading for the Pearl River Basin, USA.

    PubMed

    Joyner, Timothy Andrew; Rohli, Robert V

    2013-04-01

    Knowledge of water quality conditions is essential in assessing the health of riverine ecosystems. The goal of this study is to determine the degree to which water quality variables are related to precipitation and air temperature conditions for a segment of the Pearl River Basin near Bogalusa, LA, USA. The AQUATOX ecological fate simulation model is used to estimate daily total nitrogen, total phosphorus, and dissolved oxygen concentrations over a 2-year period. Daily modeled output for each variable was calibrated against reliably measured data to assess the accuracy. Observed data were plotted against simulated data for controlled and perturbed models for validation, and stepwise multiple regression analysis was used to quantify the relationships between the water quality and meteorological variables. Results suggest that daily dissolved oxygen is significantly negatively correlated to concurrent daily mean air temperature with a total explained variance of 0.679 (p < 0.01), and monthly dissolved oxygen is significantly negatively correlated to monthly mean air temperature with a total explained variance of 0.567 (p < 0.01). Total mean monthly phosphorus concentration is significantly positively related to the previous month's precipitation with a total explained variance of 0.302 (p < 0.01). These relationships suggest that atmospheric conditions have a strong influence on water quality in the Pearl Basin. Therefore, environmental planners should expect that future climatic changes are likely to alter water quality. PMID:22972315

  12. Influence of dissociative recombination on the LTE of argon high-frequency plasmas at atmospheric pressure

    E-print Network

    Boyer, Edmond

    at atmospheric pressure A. Sáinz1 , J. Margot2 , M. C. García1 , M. D. Calzada1 1 Grupo de Espectroscopía de+ ) are also expected to play an important role in the discharge kinetics. At atmospheric pressure obeys the Saha-Boltzmann distribution. However, at atmospheric pressure, molecular recombination

  13. Influence of atmospheric CO2 enrichment on methane consumption in a temperate forest soil

    Microsoft Academic Search

    REBECCA L. P HILLIPS; STEPHEN C. W HALEN; WILLIAM H. S CHLESINGER

    2001-01-01

    Rates of atmospheric CH4 consumption of soils in temperate forest were com- pared in plots continuously enriched with CO2 at 200 m LL -1 above ambient and in control plots exposed to the ambient atmosphere of 360 m LC O 2 L -1 . The pur- pose was to determine if ecosystem atmospheric CO2 enrichment would alter soil microbial CH4

  14. Influence of aerosol multiple scattering of ultraviolet radiation on martian atmospheric sensing

    Microsoft Academic Search

    M.-P. Zorzano; C. Córdoba-Jabonero

    2007-01-01

    The ultraviolet (UV) radiative transfer problem in the martian atmosphere is dominated by multiple scattering of photons with the micron-sized aerosols that are suspended in the thin atmosphere. By implementing a multiple stream, vertical fine layering description of the radiative transfer equation that is able to cope with the strong vertical variations of the atmospheric properties, we estimate the resulting

  15. Influence of reaction atmosphere on the liquefaction and depolymerization of wood in an ionic liquid, 1-ethyl-3-methylimidazolium chloride

    Microsoft Academic Search

    Atsushi Nakamura; Hisashi Miyafuji; Shiro Saka

    2010-01-01

    The influence of reaction atmosphere on the liquefaction and depolymerization of wood in an ionic liquid, 1-ethyl-3-methylimidazolium\\u000a chloride ([C2mim][Cl]), has been systematically studied. The wood samples were treated with [C2mim][Cl] at 120°C under various\\u000a atmospheres such as oxygen, nitrogen, and carbon dioxide, both dried and humidified. The percentage of residue after the treatment\\u000a shows that oxygen considerably accelerates the liquefaction

  16. Primary and secondary sources of formaldehyde in urban atmospheres: Houston Texas region

    NASA Astrophysics Data System (ADS)

    Parrish, D. D.; Ryerson, T. B.; Mellqvist, J.; Johansson, J.; Fried, A.; Richter, D.; Walega, J. G.; Washenfelder, R. A.; de Gouw, J. A.; Peischl, J.; Aikin, K. C.; McKeen, S. A.; Frost, G. J.; Fehsenfeld, F. C.; Herndon, S. C.

    2011-12-01

    We evaluate the rates of secondary production and primary emission of formaldehyde (CH2O) from petrochemical industrial facilities and on-road vehicles in the Houston Texas region. This evaluation is based upon ambient measurements collected during field studies in 2000, 2006 and 2009. The predominant CH2O source (92 ± 4% of total) is secondary production formed during the atmospheric oxidation of highly reactive volatile organic compounds (HRVOCs) emitted from the petrochemical facilities. Smaller contributions are primary emissions from these facilities (4 ± 2%), and secondary production (~3%) and primary emissions (~1%) from vehicles. The primary emissions from both sectors are well quantified by current emission inventories. Since secondary production dominates, control efforts directed at primary CH2O emissions cannot address the large majority of CH2O sources in the Houston area, although there may still be a role for such efforts. Ongoing efforts to control alkene emissions from the petrochemical facilities, as well as volatile organic compound emissions from the motor vehicle fleet, will effectively reduce the CH2O concentrations in the Houston region. We have not addressed other emission sectors, such as off-road mobile sources or secondary formation from biogenic hydrocarbons. Previous analyses based on correlations between ambient concentrations of CH2O and various marker species have suggested much larger primary emissions of CH2O, but those results neglect confounding effects of dilution and loss processes, and do not demonstrate the causes of the observed correlations. Similar problems must be suspected in any source apportionment analysis of secondary species based upon correlations of ambient concentrations of pollutants.

  17. Primary and secondary sources of formaldehyde in urban atmospheres: Houston Texas region

    NASA Astrophysics Data System (ADS)

    Parrish, D. D.; Ryerson, T. B.; Mellqvist, J.; Johansson, J.; Fried, A.; Richter, D.; Walega, J. G.; Washenfelder, R. A.; de Gouw, J. A.; Peischl, J.; Aikin, K. C.; McKeen, S. A.; Frost, G. J.; Fehsenfeld, F. C.; Herndon, S. C.

    2012-04-01

    We evaluate the rates of secondary production and primary emission of formaldehyde (CH2O) from petrochemical industrial facilities and on-road vehicles in the Houston Texas region. This evaluation is based upon ambient measurements collected during field studies in 2000, 2006 and 2009. The predominant CH2O source (92 ± 4% of total) is secondary production formed during the atmospheric oxidation of highly reactive volatile organic compounds (HRVOCs) emitted from the petrochemical facilities. Smaller contributions are primary emissions from these facilities (4 ± 2%), and secondary production (~3%) and primary emissions (~1%) from vehicles. The primary emissions from both sectors are well quantified by current emission inventories. Since secondary production dominates, control efforts directed at primary CH2O emissions cannot address the large majority of CH2O sources in the Houston area, although there may still be a role for such efforts. Ongoing efforts to control alkene emissions from the petrochemical facilities, as well as volatile organic compound emissions from the motor vehicle fleet, will effectively reduce the CH2O concentrations in the Houston region. We do not address other emission sectors, such as off-road mobile sources or secondary formation from biogenic hydrocarbons. Previous analyses based on correlations between ambient concentrations of CH2O and various marker species have suggested much larger primary emissions of CH2O, but those results neglect confounding effects of dilution and loss processes, and do not demonstrate the causes of the observed correlations. Similar problems must be suspected in any source apportionment analysis of secondary species based upon correlations of ambient concentrations of pollutants.

  18. Socioeconomic influences on benzodiazepine consumption in an Irish Region.

    PubMed

    Quigley, P; Usher, C; Bennett, K; Feely, J

    2006-01-01

    Misuse of prescription sedatives is a significant problem for addiction treatment services. The aim of this study was to examine the prescribing of diazepam in disadvantaged Irish communities, and to identify factors which may predict diazepam consumption in that population. We examined prescribing trends for those aged 16-69 years in 2002 in a region of the state-funded General Medical Services Scheme. Material deprivation was based on the 2002 Small Area Health Research Unit (SAHRU) deprivation index. The average defined daily dose (DDD) was calculated and logistic regression analysis was used to predict diazepam use by age, gender and deprivation index. Results showed that patients living in the most-deprived areas were more likely to receive diazepam than patients living in the least-deprived areas (OR = 1.21, 95% CI 1.15-1.27). Female patients living in the most-deprived areas were also more likely to receive diazepam than those living in the least-deprived areas (OR = 1.36, 95% CI 1.18-1.57). It is concluded that there is a pattern of higher diazepam prescribing in areas of greatest deprivation, where prescription sedatives play a complex role within troubled families. PMID:16778435

  19. The influence of the upper-atmosphere neutral particle density on the occurrence of equatorial spread-F

    Microsoft Academic Search

    G. G. Bowman

    1993-01-01

    Over extended periods of time spread-F occurrence is considered in equatorial latitudes at stations located in the region between the geomagnetic equator and the equatorial anomaly crest region. Distinct differences are observed in the annual and sunspot-cycle distributions for spread-F occurrence before midnight and after midnight. The paper proposes that before midnight the low upper-atmosphere neutral-particle densities (NPDs) at elevated

  20. Overview of the Atmospheric Brown Cloud East Asian Regional Experiment 2005 and a study of the aerosol direct radiative forcing in east Asia

    Microsoft Academic Search

    Teruyuki Nakajima; Soon-Chang Yoon; Veerabhadran Ramanathan; Guang-Yu Shi; Toshihiko Takemura; Akiko Higurashi; Tamio Takamura; Kazuma Aoki; Byung-Ju Sohn; Sang-Woo Kim; Haruo Tsuruta; Nobuo Sugimoto; Atsushi Shimizu; Hiroshi Tanimoto; Yousuke Sawa; Neng-Huei Lin; Chung-Te Lee; Daisuke Goto; Nick Schutgens

    2007-01-01

    This article introduces an international regional experiment, East Asian Regional Experiment 2005 (EAREX 2005), carried out in March–April 2005 in the east Asian region, as one of the first phase regional experiments under the UNEP Atmospheric Brown Cloud (ABC) project, and discusses some outstanding features of aerosol characteristics and its direct radiative forcing in the east Asian region, with some

  1. Local and regional factors affecting atmospheric mercury speciation at a remote location

    USGS Publications Warehouse

    Manolopoulos, H.; Schauer, J.J.; Purcell, M.D.; Rudolph, T.M.; Olson, M.L.; Rodger, B.; Krabbenhoft, D.P.

    2007-01-01

    Atmospheric concentrations of elemental (Hg0), reactive gaseous (RGM), and particulate (PHg) mercury were measured at two remote sites in the midwestern United States. Concurrent measurements of Hg0, PHg, and RGM obtained at Devil's Lake and Mt. Horeb, located approximately 65 km apart, showed that Hg0 and PHg concentrations were affected by regional, as well as local sources, while RGM was mainly impacted by local sources. Plumes reaching the Devil's Lake site from a nearby coal-fired power plant significantly impacted SO2 and RGM concentrations at Devil's Lake, but had little impact on Hg0. Our findings suggest that traditional modeling approaches to assess sources of mercury deposited that utilize source emissions and large-scale grids may not be sufficient to predict mercury deposition at sensitive locations due to the importance of small-scale sources and processes. We suggest the use of a receptor-based monitoring to better understand mercury source-receptor relationships. ?? 2007 NRC Canada.

  2. A Regional Atmospheric Continuous CO2 Network In The Rocky Mountains (Rocky RACCOON)

    NASA Astrophysics Data System (ADS)

    Stephens, B.; de Wekker, S.; Watt, A.; Schimel, D.

    2005-12-01

    We have established a continuous CO2 observing network in the Rocky Mountains, building on technological and modeling advances made during the Carbon in the Mountains Experiment (CME), to improve our understanding of regional carbon fluxes and to fill key gaps in the North American Carbon Program (NACP). We will present a description of the Rocky RACCOON network and early results from the first three sites. There are strong scientific and societal motivations for determining CO2 exchanges on regional scales. NACP aims to address these concerns through a dramatic expansion in observations and modeling capabilities over North America. Mountain forests in particular represent a significant potential net CO2 sink in the U.S. and are highly sensitive to land-use practices and climate change. However, plans for new continuous CO2 observing sites have omitted the mountain west. This resulted from expensive instrumentation in the face of limited resources, and a perception that current atmospheric transport models are not sophisticated enough to interpret CO2 measurements made in complex terrain. Through our efforts in CME, we have a new autonomous, inexpensive, and robust CO2 analysis system and are developing mountain CO2 modeling tools that will help us to overcome these obstacles. Preliminary observational and modeling results give us confidence that continuous CO2 observations from mountain top observatories will provide useful constraints on regional carbon cycling and will be valuable in the continental inverse modeling efforts planned for NACP. We began at three Colorado sites in August 2005 and hope to add three to six sites in other western states in subsequent years, utilizing existing observatories to the maximum extent possible. The first three sites are at Niwot Ridge, allowing us to have an ongoing intercomparison with flask measurements made by NOAA CMDL; at Storm Peak Laboratory near Steamboat Springs, allowing us to investigate comparisons between these two relatively nearby sites; and at Fraser Experimental Forest, allowing us to investigate nocturnal respiration rates across a large intermountain valley. Our data are available to the public on the internet in near real time to support quality control, local science, and larger scale synthesis efforts.

  3. F2-region atmospheric gravity waves due to high-power HF heating and subauroral polarization streams

    NASA Astrophysics Data System (ADS)

    Mishin, E.; Sutton, E.; Milikh, G.; Galkin, I.; Roth, C.; Förster, M.

    2012-06-01

    We report the first evidence of atmospheric gravity waves (AGWs) generated in the F2 region by high-power HF heating and subauroral polarization streams. Data come from the CHAMP and GRACE spacecraft overflying the High-frequency Active Auroral Research Program (HAARP) heating facility. These observations facilitate a new method of studying the ionosphere-thermosphere coupling in a controlled fashion by using various HF-heating regimes. They also reveal the subauroral F2 region to be a significant source of substorm AGWs, in addition to the well-known auroral E region.

  4. Do aerosols influence the diurnal variation of H2O2 in the atmosphere?

    NASA Astrophysics Data System (ADS)

    Liang, H.; Chen, Z.; Wu, Q.; Huang, D.; Zhao, Y.

    2013-12-01

    Hydrogen peroxide (H2O2) and organic peroxides are crucial reactive species that are involved in the cycling of HOx (OH and HO2) radicals and the formation of secondary inorganic and organic aerosols in the atmosphere. Despite the importance of peroxides, their formation and removal mechanisms with the coexistence of aerosols are as yet less well known. From June 10 to July 15 2013, summertime surface measurements for atmospheric peroxides were simultaneously obtained in urban Beijing (UB) and Gucheng (GC). The UB site is located in the northern downtown of Beijing city, while the GC site is a rural site located in the North China Plain and ~100 km southwest of Beijing. In both sites, the major peroxides were determined to be H2O2, methyl hydroperoxide (MHP), peroxyformic acid (PFA) and peroxyacetic acid (PAA). By comparing the concentrations of PFA and PAA in the gas phase and rainwater, for the first time, we estimated the Henry's law constant for PFA as ~210 M atm-1 at 298 K, a quarter of that for PAA. Interestingly, we observed different H2O2 profiles in the two sites as follows: (i) the average concentration of H2O2 in UB was 50% higher than that in GC; (ii) H2O2 in GC reached its peak concentration at around 15:30, whereas the peak concentration in UB appeared at as late as 21:00; and (iii) the daily variation of H2O2 in GC generally kept consistent with that of O3 and organic peroxides while it was not always the case in UB. These differences indicate a hitherto unrecognized storage-release mechanism for H2O2 in UB, that is, an extra sink in the noontime and an extra source in the early evening. The extra source of H2O2 would enhance the aerosol phase OH radical in the early evening by the Fenton reaction. A box model analysis shows that the impacts of aerosols were majorly responsible to this unrecognized mechanism, although NOx, regional transport and planet boundary layer height also contributed a minor part. Aerosols participated in the storage-release mechanism in two potential ways. The first is the catalytic reaction of aerosol-phase soluble transition metal ions (ATMIs). ATMIs could convert HO2 to either H2O or H2O2, depending on their abundance and composition. In UB, the high ATMIs are presumed to convert most HO2 to H2O in the noontime and to H2O2 in the early evening, resulting in a different diurnal profile of H2O2. The second is the formation and hydrolysis of H2O2-related complex. In the noontime, H2O2 could be taken up onto the aerosols and then combine with organic matters to form complexes such as hydroxyalkyl hydroperoxides and secondary organic aerosols. In the early evening, however, these complexes could hydrolyze to generate H2O2 and release into the gas phase. The impacts of aerosols on H2O2, and probably on HO2 radicals over the polluted regions should be taken into consideration in the atmospheric model.

  5. Wildfire and the atmosphere: Modelling the chemical and dynamic interactions at the regional scale

    NASA Astrophysics Data System (ADS)

    Strada, S.; Mari, C.; Filippi, J.-B.; Bosseur, F.

    2012-05-01

    Forest fires release significant amounts of trace gases and aerosols into the atmosphere. Depending on meteorological conditions, fire emissions can efficiently reduce air quality and visibility, even far away from emission sources. In 2005, an arson forest fire burned nearly 700 ha near Lançon-de-Provence, southeast France. This paper explores the impact of this Mediterranean fire on the atmospheric dynamics and chemistry downwind of the burning region. The fire smoke plume was observed by the MODIS-AQUA instrument several kilometres downwind of the burning area out of the Mediterranean coast. Signatures of the fire plume on air pollutants were measured at surface stations in southeastern France by the air quality network AtmoPACA. Ground-based measurements revealed unusually high concentrations of aerosols and a well marked depletion of ozone concentrations on the day of the fire. The Lançon-de-Provence fire propagation was successfully simulated by the semi-physical fire spread model ForeFire. ForeFire provided the burnt area at high temporal and spatial resolutions. The burnt areas were scaled to compute the fire heat and water vapour fluxes in the three-dimensional meso-scale non-hydrostatic meteorological model MesoNH. The simulated fire plume kept confined in the boundary layer with high values of turbulent kinetic energy. The plume was advected several kilometres downwind of the ignition area by the Mistral winds in accordance with the MODIS and AtmoPACA observations. The vertical plume development was found to be more sensitive to the sensible heat flux than to the fire released moisture. The burnt area information is also used to compute emissions of a fire aerosol-like tracer and gaseous pollutants, using emission factors for Mediterranean vegetation. The coupled model simulated high concentrations of the fire aerosol-like tracer downwind of the burning zone at the right timing compared to ground-based measurements. A chemical reaction mechanism was coupled on-line to the MesoNH model to account for gaseous chemistry evolution in the fire plume. High levels of ozone precursors (NOx, CO) were simulated in the smoke plume which led to the depletion of ozone levels above and downwind of the burning zone. This depletion of ozone was indeed observed at ground-based stations but with a higher impact than simulated. The difference may be explained by the simplified design of the model with no anthropogenic sources and no interaction of the smoke aerosols with the photolysis rates. Ozone production was modelled tens of kilometres downwind of the ignition zone out of the coast.

  6. Anthropogenic Aerosol Radiative Forcing in Asia Derived From Regional Models With Atmospheric and Aerosol Data Assimilation

    SciTech Connect

    Chung, Chul Eddy; Ramanathan, V.; Carmichael, Gregory; Kulkarni, S.; Tang, Youhua; Adhikary, Bhupesh; Leung, Lai-Yung R.; Qian, Yun

    2010-07-05

    A high-resolution estimate of monthly 3D aerosol solar heating rates and surface solar fluxes in Asia from 2001 to 2004 is described here. This product stems from an Asian aerosol assimilation project, in which a) the PNNL regional model bounded by the NCEP reanalyses was used to provide meteorology, b) MODIS and AERONET data were integrated for aerosol observations, c) the Iowa aerosol/chemistry model STEM-2K1 used the PNNL meteorology and assimilated aerosol observations, and d) 3D (X-Y-Z) aerosol simulations from the STEM-2K1 were used in the Scripps Monte-Carlo Aerosol Cloud Radiation (MACR) model to produce total and anthropogenic aerosol direct solar forcing for average cloudy skies. The MACR model and STEM both used the PNNL model resolution of 0.45º×0.4º in the horizontal and of 23 layers in the troposphere. The 2001–2004 averaged anthropogenic all-sky aerosol forcing is ?1.3 Wm-2 (TOA), +7.3 Wm-2 (atmosphere) and ?8.6 Wm-2 (surface) averaged in Asia (60?138°E & Eq. ?45°N). In the absence of AERONET SSA assimilation, absorbing aerosol concentration (especially BC aerosol) is much smaller, giving ?2.3 Wm-2 (TOA), +4.5 Wm-2 (atmosphere) and ?6.8 Wm-2 (surface), averaged in Asia. In the vertical, monthly forcing is mainly concentrated below 600hPa with maxima around 800hPa. Seasonally, low-level forcing is far larger in dry season than in wet season in South Asia, whereas the wet season forcing exceeds the dry season forcing in East Asia. The anthropogenic forcing in the present study is similar to that in Chung et al.’s [2005] in overall magnitude but the former offers fine-scale features and simulated vertical profiles. The interannual variability of the computed anthropogenic forcing is significant and extremely large over major emission outflow areas. In view of this, the present study’s estimate is within the implicated range of the 1999 INDOEX result. However, NCAR/CCSM3’s anthropogenic aerosol forcing is much smaller than the present study’s estimate at the surface, and is outside of what the INDOEX findings can support.

  7. Influence of climate change on the water resources in an alpine region.

    PubMed

    De Toffol, S; Engelhard, C; Rauch, W

    2008-01-01

    It is widely accepted that the global warming will impact on water resources. This study investigates the possible influence of climate change on the water resources in an alpine region. A description of the actual situation with emphasis on the water resources from the one side and on the water consuming factors, here called stressors, is given. The probable effects of climate change in the region and their influence on its water resources are then described. The main outcome is that in the analysed region the climate change will rather have positive influence on the water balance by inducing higher precipitations during the rivers' natural low flow period (winter). This outcome contradicts many common predictions, however, this due to the specifics induced by the alpine nature of the catchment. PMID:18776619

  8. Towards Fully Coupled Atmosphere-Hydrology Model Systems: Recent Developments and Performance Evaluation For Different Climate Regions

    NASA Astrophysics Data System (ADS)

    Kunstmann, Harald; Fersch, Benjamin; Rummler, Thomas; Wagner, Sven; Arnault, Joel; Senatore, Alfonso; Gochis, David

    2015-04-01

    Limitations in the adequate representation of terrestrial hydrologic processes controlling the land-atmosphere coupling are assumed to be a significant factor currently limiting prediction skills of regional atmospheric models. The necessity for more comprehensive process descriptions accounting for the interdependencies between water- and energy fluxes at the compartmental interfaces are driving recent developments in hydrometeorological modeling towards more sophisticated treatment of terrestrial hydrologic processes. It is particularly the lateral surface and subsurface water fluxes that are neglected in standard regional atmospheric models. Current developments in enhanced lateral hydrological process descriptions in the WRF model system will be presented. Based on WRF and WRF-Hydro, new modules and concepts for integrating the saturated zone by a 2-dim groundwater scheme and coupling approaches to the unsaturated zone will be presented. The fully coupled model system allows to model the complete regional water cycle, from the top of the atmosphere, via the boundary layer, the land surface, the unsaturated zone and the saturated zone till the flow in the river beds. With this increasing complexity, that also allows to describe the complex interaction of the regional water cycle on different spatial and temporal scales, the reliability and predictability of model simulations can only be shown, if performance is tested for a variety of hydrological variables for different climatological environments. We will show results of fully coupled simulations for the regions of sempiternal humid Southern Bavaria/Germany (rivers Isar and Ammer) and semiarid to subhumid Westafrica (river Sissilli). In both regions, in addition to streamflow measurements, also the validation of heat fluxes is possible via Eddy-Covariance stations within hydrometeorological testbeds. In the German Isar/Ammer region, e.g., we apply the extended WRF-Hydro modeling system in 3km atmospheric- grid resolution and 300m subsurface-grid resolution for the terrestrial hydrological processes. Our simulations comprise the period May 2004 till September 2005 with a special focus on the August 2005 century flooding event. For streamflow at selected gauges we achieve Nash-Sutcliff efficiencies of 0.86 in uncoupled mode (using observed meteorological driving) and of 0.49 in fully coupled mode of WRF-Hydro. In the West African Sissilli catchment our focus is on the year 2003. We apply WRF-Hydro in 2km atmospheric- and 500m subsurface horizontal resolutions and achieve Nash-Sutcliff efficiencies of 0.4. Finally, a further validation of energy balance components obtained from EC-stations is shown and the sensitivity and differences of the fully coupled model system to corresponding uncoupled and one-way coupled mode results are discussed.

  9. Response of atmosphere circulation on global and regional scales to the two El Niño flavors

    NASA Astrophysics Data System (ADS)

    Zheleznova, Irina; Gushchina, Daria

    2015-04-01

    El Niño - Southern Oscillation (ENSO) is one of the most striking anomalies in the climate system of our planet. Recently it has been established [Ashok et al., 2007; Kug et al., 2009] that El Niño appears in two different flavors: the canonical El Niño, which is characterized by the maximum SST anomalies in the eastern Pacific, and El Niño Modoki with maximum anomalies localized in the center of the Pacific Ocean, near the date line. Recent studies demonstrated [Ashok et al., 2007; Weng et al., 2009; Mo, 2010 et al.] that the remote response to the two types of El Niño is drastically different, being opposite in some areas. Based on the regression analysis the air temperature and precipitation anomalies observed during canonical and Modoki El Niño were defined. However, the structure and mechanisms of this response are fairly understood. A comprehensive analysis of the atmospheric circulation anomalies resulted from two types of El Niño may emerge the causes of different remote response associated to the two types of El Niño. The large-scale zonal atmospheric circulation response to El Niño is characterized by the poleward propagation of the signal from the equatorial and tropical latitudes. El Niño is associated with the intensification of western currents in mid latitudes and equatorial belt in the low troposphere and decreasing of the easterlies in tropics. The global circulation response is more intensive during El Niño Modoki as compare to the canonical El Niño. However, the spatial structure of the response is similar for the both types of El Niño. El Niño induces drastic anomalies in vertical circulation. It is shown that Hadley and Walker circulation anomalies associated to the Canonical and Modoki El Niño have different space localization and timing. Canonical El Niño is characterized by anomalous ascending motion in central and eastern Pacific localized near the equator and in the equatorial regions of the Southern Hemisphere. Over Indonesia, south to the equator prevails air descent. During El Niño Modoki anomalous air rising occurs over the central equatorial Pacific, while descending motion develop to the east (mainly in the equatorial regions of the Southern Hemisphere) and to the west (in the Northern Hemisphere). The structure of the anomalies of vertical cells outside the Pacific region differ over the Western Indian Ocean and East Africa, South America and the Caribbean. The analysis of regional circulation response to the El Niño revealed that in the Northern Hemisphere the intensity of the response is comparable for two types of El Niño, while in the Southern Hemisphere the circulation anomalies are more pronounced during the El Niño Modoki. All atmosphere centers of actions under investigation were divided into four groups according to the character of circulation response to the two types of El Niño: 1 - centers of action with similar response to both types of El Niño; 2 - centers of action with different response to canonical and Modoki El Niño; 3 - centers of action, having significant correlations with only one type of El Niño; 4 - centers of action with no significant relationships with two types of El Niño. It is suggested that the difference in weather anomalies observed during the two types of El Niño are mostly associated to the circulation anomalies in the centers of action and in the vertical cells which differs between canonical and Modoki El Niño. References: 1. Ashok K., Behera S. K., Rao S. A., Weng H., Yamagata, T. El Nino Modoki and its possible teleconnection. J. Geophys. Res. 2007, 112, C11007, doi:10.1029/2006JC003798. 2. Kug, J.S., Jin F.F. and An S.I. Two types of El Niño events:Cold tongue El Niño and warm pool El Niño. // J. Clim., 2009, vol. 22, pp. 1499-1515. 3. Mo, K. C., Interdecadal modulation of the impact of ENSO on precipitation and temperature over the United States, J. Clim., 2010, 23, 3639-3656, doi:10.1175/2010JCLI3553.1. 4. Weng H., Behera S. K. and Yamagata T. Anomalous winter climate conditions in the Pacific Rim during recent El N

  10. Influence of Atmospheric Modes of Variability on Mediterranean Sea Surface Heat Exchange from a 12km Dynamically Downscaled Reanalysis

    NASA Astrophysics Data System (ADS)

    Josey, Simon; Somot, Samuel

    2014-05-01

    Earlier research on the impacts of the first four modes of atmospheric variability in the North Atlantic / Europe region on air-sea heat exchange in the Mediterranean Sea will be extended to higher spatial resolution using the ALADIN 12 km dynamical downscaling of the ERA-Interim reanalysis. Observation based indices of the modes from the NOAA Climate Prediction Centre (CPC) are used together with the 12 km ALADIN surface flux fields for the period 1979-2012 to determine the sensitivity of the mean heat budget of the full Mediterranean basin and the eastern and western sub-basins to surface forcing at higher resolutions than previously considered. The four modes are the North Atlantic Oscillation (NAO), East Atlantic pattern (EA), Scandinavian pattern (SCAN) and East Atlantic / West Russian pattern (EA/WR). Results at coarser resolution using the NCEP/NCAR and 50 km resolution ARPERA reanalysis will also be reviewed. These indicate that winter anomalies dominate the annual mean heat budget and the leading mode, the NAO, has a surprisingly small impact on the full basin winter mean heat budget, < 5 Wm-2. In contrast, the EA mode has a major effect, of order 25 Wm-2, with similar impacts on both the eastern and western Mediterranean. The SCAN mode has the weakest influence of those considered. The EA/WR mode plays a significant role but, in contrast to the EA mode, it generates a dipole in the heat exchange with an approximately equal and opposite signal of about 15 Wm-2 on the eastern and western sub-basins. New results will be presented which reveal the extent to which these earlier conclusions still hold at the higher 12km resolution now possible using ALADIN.

  11. Strong control of surface roughness variations on the simulated dry season regional atmospheric response to contemporary deforestation in Rondônia, Brazil

    NASA Astrophysics Data System (ADS)

    Khanna, Jaya; Medvigy, David

    2014-12-01

    The atmospheric effects of Amazon deforestation have frequently been studied in the context of small scales (?1 km) and very large scales (hundreds of kilometers). However, analysis of intermediate-scale deforestation (tens of kilometers) has received less attention, despite the fact that it better represents the contemporary landscape in some parts of the Amazon. In this study, the dynamic and thermodynamic effects of contemporary intermediate-scale deforestation in Rondônia, Brazil are investigated through variable resolution Global Circulation Model (GCM) simulations carried out with the Ocean-Land-Atmosphere Model. In particular, the atmospheric response to surface roughness changes brought about by deforestation is emphasized. This study shows that reductions in surface roughness associated with intermediate-scale deforestation give rise to a mesoscale circulation. This circulation is capable of convective triggering, but it also weakens the turbulent exchange of energy between land and atmosphere. Furthermore, this mesoscale circulation has distinct impacts on the hydroclimates of the western and eastern halves of Rondônia, increasing shallow cloudiness in the former while suppressing it in the latter. These results show that the atmospheric response to contemporary intermediate-scale deforestation in Rondônia is likely to be more influenced by differences in surface roughness between forest and forest clearings than by the differences in the surface energy partitioning.

  12. Influence of Vegetation and Seasonal Forcing on Carbon Dioxide Fluxes Across the Upper Midwest, USA: Implications for Regional Scaling

    SciTech Connect

    Desai, Ankur R.; Noormets, Asko; Bolstad, Paul V.; Chen, Jiquan; Cook, Bruce D.; Davis, Kenneth J.; Euskirchen, Eugenie S.; Gough, Christopher; Martin, Jonathan G.; Ricciuto, Daniel M.; Schmid, Hans P.; Tang, Jianwu; Wang, Weiguo

    2008-02-13

    Carbon dioxide fluxes were examined over the growing seasons of 2002 and 2003 from 14 different sites in the Upper Midwest (USA) to assess spatial variability of ecosystem–atmosphere CO2 exchange. These sites were exposed to similar temperature/precipitation regimes and spanned a range of vegetation types typical of the region (northern hardwood, mixed forest, red pine, jack pine, pine barrens, and shrub wetland). The hardwood and red pine sites also spanned a range of stand ages (young, intermediate, mature). While seasonal changes in net ecosystem exchange (NEE) and photosynthetic parameters were coherent across the 2 years at most sites, changes in ecosystem respiration (ER) and gross ecosystem production (GEP) were not. Canopy height and vegetation type were important variables for explaining spatial variability of CO2 fluxes across the region. Light-use efficiency (LUE) was not as strongly correlated to GEP as maximum assimilation capacity (Amax). A bottom-up multi-tower land cover aggregated scaling of CO2 flux to a 2000 km2 regional flux estimate found June to August 2003 NEE, ER, and GEP to be ?290 ± 89, 408 ± 48, and 698 ± 73 gC m?2, respectively. Aggregated NEE, ER, and GEP were 280% larger, 32% smaller and 3% larger, respectively, than that observed from a regionally integrating 447 m tall flux tower. However, when the tall tower fluxes were decomposed using a footprint-weighted influence function and then re-aggregated to a regional estimate, the resulting NEE, ER, and GEP were within 11% of the multi-tower aggregation. Excluding wetland and young stand age sites from the aggregation worsened the comparison to observed fluxes. These results provide insight on the range of spatial sampling, replication, measurement error, and land cover accuracy needed for multi-tiered bottom-up scaling of CO2 fluxes in heterogeneous regions such as the Upper Midwest, USA.

  13. Influence of vegetation and seasonal forcing on carbon dioxide fluxes across the Upper Midwest, USA: Implications for regional scaling

    SciTech Connect

    Desai, Desai Ankur R. [University of Wisconsin, Madison; Noormets, Asko [North Carolina State University; Bolstad, Paul V [University of Minnesota; Chen, Jiquan [University of Toledo, Toledo, OH; Cook, Bruce D [University of Minnesota, St Paul; Davis, Kenneth [Pennsylvania State University; Euskirchen, Eugenie S [University of Alaska; Gough, Christopher M [Ohio State University; Martin, Jonathan G [Oregon State University, Corvallis; Ricciuto, Daniel M [ORNL; Schmid, Hans Peter [Indiana University; Tang, Jianwu [Chicago Botanical Garden, Glencoe, Illiinois; Wang, Weiguo [Pacific Northwest National Laboratory (PNNL)

    2008-01-01

    Carbon dioxide fluxes were examined over the growing seasons of 2002 and 2003 from 14 different sites in Upper Midwest (USA) to assess spatial variability of ecosystem atmosphere CO2 exchange. These sites were exposed to similar temperature/precipitation regimes and spanned a range of vegetation types typical of the region (northern hardwood, mixed forest, red pine, jack pine, pine barrens and shrub wetland). The hardwood and red pine sites also spanned a range of stand ages (young, intermediate, mature). While seasonal changes in net ecosystem exchange (NEE) and photosynthetic parameters were coherent across the 2 years at most sites, changes in ecosystem respiration (ER) and gross ecosystem production (GEP) were not. Canopy height and vegetation type were important variables for explaining spatial variability of CO2 fluxes across the region. Light-use efficiency (LUE) was not as strongly correlated to GEP as maximum assimilation capacity (Amax). A bottom-up multi-tower land cover aggregated scaling of CO2 flux to a 2000 km2 regional flux estimate found June to August 2003 NEE, ER and GEP to be 290 89, 408, 48, and 698, 73 gC m-2, respectively. Aggregated NEE, ER and GEP were 280% larger, 32% smaller and 3% larger, respectively, than that observed from a regionally integrating 447m tall flux tower. However, when the tall tower fluxes were decomposed using a footprint-weighted influence function and then reaggregated to a regional estimate, the resulting NEE, ER and GEP were within 11% of the multi-tower aggregation. Excluding wetland and young stand age sites from the aggregation worsened the comparison to observed fluxes. These results provide insight on the range of spatial sampling, replication, measurement error and land cover accuracy needed for multi-tiered bottom-up scaling of CO2 fluxes in heterogeneous regions such as the Upper Midwest, USA.

  14. Acoustic-gravity waves in the nonisothermal atmosphere and its influence on the magnetospheric quasi-periodic vlf emissions

    NASA Astrophysics Data System (ADS)

    Savina, Olga; Bespalov, Peter; Misonova, Vera; Petrov, Kiril

    2014-05-01

    We examine two mutually complementing tasks related to the theoretical analysis of acoustic-gravity disturbances in the Earth's atmosphere and its influence on magnetosphere processes. Our research is based on modern atmospherical models. We study waves propagation, absorption, and filtration. The atmospheric nonisothermicity is taken into account, for example, by introduction of a two-layered atmosphere temperature model. For a study of more delicate effects, a piecewise-linear model, for which the analytical solution is written by the hypergeometric functions, is employed. Also we consider an influence of acoustic-gravity waves on VLF electromagnetic wave excitation in the magnetosphere. This influence occurs as a result of the following processes: a modulation of the plasma density by acoustic-gravity waves in the ionosphere, a modulation of reflection from the ionosphere for VLF waves, and a modification of the magnetospheric resonator Q-factor for VLF waves. Variation of the magnetospheric resonator Q-factor has an influence on the operation of the plasma magnetospheric maser, where the active substances are radiation belts particles and the working modes are electromagnetic VLF waves (whistler-type waves). The plasma magnetospheric maser can be responsible for an excitation of self-oscillations. These self-oscillations are frequently characterized by alternating stages of accumulation and precipitation of energetic particles into the ionosphere during a pulse of whistler emissions. Numerical and analytical investigations of the response of self-oscillations to harmonic oscillations of the whistler reflection coefficient shows that even a small modulation rate can significantly changes the magnetospheric VLF emissions. Our results can explain the causes of the modulation of energetic electron fluxes and whistler wave intensity with a time scale from 10 to 150 seconds in the day-side magnetosphere. Such quasi-periodic VLF emissions are often observed in the sub-auroral and auroral magnetosphere and have a noticeable effect on the formation of the space weather phenomena.

  15. Sporadic E layer at mid-latitudes: average properties and influence of atmospheric tides

    NASA Astrophysics Data System (ADS)

    Pignalberi, A.; Pezzopane, M.; Zuccheretti, E.

    2014-11-01

    This paper describes a study of the daily variability shown by the main characteristics of the sporadic E (Es) layer, that is the top frequency (ftEs) and the lowest virtual height (h'Es). The study is based on ionograms recorded by the Advanced Ionospheric Sounder by the Istituto Nazionale di Geofisica e Vulcanologia (AIS-INGV) ionosondes installed in the ionospheric stations at Rome (41.8° N, 12.5° E) and Gibilmanna (37.9° N, 14.0° E), Italy, during the summer (June, July, August and September) of 2013, a year falling in the ascending phase of solar cycle 24. The ftEs presents a diurnal variation characterized by two maxima, the first around noon is very well defined and the second in the evening/night is much less defined; the amplitude of both maxima decreases from June to September accompanied by a general decrease of the ftEs values which is more pronounced in the daytime than in the nighttime. h'Es also presents a diurnal variation characterized by two maxima but, unlike ftEs, these present the same amplitude which is independent from the considered month. Assuming that both ftEs and h'Es trends are influenced by the atmospheric tides, the height-time-intensity (HTI) technique was applied to deeply investigate how these waves control the Es dynamics. The HTI study, along with a fast Fourier transform analysis, show that a well-defined semidiurnal periodicity characterizes the Es layer dynamics most accurately in June and July, while in August and September the daytime semidiurnal periodicity becomes weaker and the role of the diurnal periodicity is consequently highlighted.

  16. Influence of Gas Flow on Plasma Length in Atmospheric Pressure Plasma Jet

    NASA Astrophysics Data System (ADS)

    Yambe, Kiyoyuki; Furuichi, Tsubasa; Ogura, Kazuo

    We have studied atmospheric pressure plasma generated using a quartz tube, helium gas and foil electrode by applying RF high voltage. The atmospheric pressure plasma in the form of bullet is released like as a plume into the atmosphere. The travel length of plasma increases by increasing the gas flow rate in the laminar flow. The tip of plasma jet is disturbed by the turbulent flow which develops due to the decrease of helium gas ratio on the cross-section.

  17. Cloud and rain processes in a biosphere-atmosphere interaction context in the Amazon Region

    Microsoft Academic Search

    M. A. F. Silva Dias; S. Rutledge; P. Kabat; P. L. Silva Dias; C. Nobre; G. Fisch; A. J. Dolman; E. Zipser; M. Garstang; A. O. Manzi; J. D. Fuentes; H. R. Rocha; J. Marengo; A. Plana-Fattori; L. D. A. Sa ´; R. C. S. Alvala; M. O. Andreae; P. Artaxo; R. Gielow; L. Gatti

    2002-01-01

    This paper presents an overview of the results from the first major mesoscale atmospheric campaign of the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) Program. The campaign, collocated with a Tropical Rainfall Measuring Mission (TRMM) satellite validation campaigns, was conducted in southwest Rondônia in January and February 1999 during the wet season. Highlights on the interaction between clouds, rain, and the

  18. Regional climate change in Portugal: precipitation variability associated with large-scale atmospheric circulation

    NASA Astrophysics Data System (ADS)

    Corte-Real, João; Qian, Budong; Xu, Hong

    1998-05-01

    Four major circulation patterns, associated with daily precipitation in Portugal, are classified from daily sea level pressure fields over the northeastern Atlantic and western Europe, based on the K-means clustering algorithm coupled with principal component analysis. A rainy pattern is clearly identified with a probability of rain of 74.6%, as well as two distinct dry patterns, one prevailing in summer and the other occurring frequently in winter; a blocking-like pattern with a probability of rain of 36.8% has also been identified. These patterns are quasi-stationary, normally persisting for 1 week and sometimes even for 1 month, especially the dry ones; they represent the principal weather regimes associated with precipitation in Portugal.Interannual variations in monthly precipitation associated with the circulation patterns are also investigated; results show that these variations match fluctuations in the frequencies of occurrence of both the rainy and the dry patterns. The decreasing trend of March monthly rainfall in southern Portugal is closely related to corresponding trends in the frequencies of both the rainy pattern and the summer dry pattern. Long term trends are not significant either in other monthly rainfall sequences or in the frequencies of different circulation patterns. Interannual variations seem, in most months, to be quasi-periodic. Singular spectrum analysis (SSA) is performed on these sequences to detect quasi-periodic oscillations. Relationships between oscillations in rainfall and in frequencies of occurrence of circulation patterns are studied. Results show that four weather circulation patterns or weather regimes are important for investigating regional climate change in Portugal and its relationship with variability of large-scale atmospheric circulation.

  19. EVIDENCE FOR WIDESPREAD COOLING IN AN ACTIVE REGION OBSERVED WITH THE SDO ATMOSPHERIC IMAGING ASSEMBLY

    SciTech Connect

    Viall, Nicholeen M.; Klimchuk, James A. [NASA Goddard Space Flight Center, Solar Physics Laboratory, Greenbelt, MD 20706 (United States)

    2012-07-01

    A well-known behavior of EUV light curves of discrete coronal loops is that the peak intensities of cooler channels or spectral lines are reached at progressively later times than hotter channels. This time lag is understood to be the result of hot coronal loop plasma cooling through these lower respective temperatures. However, loops typically comprise only a minority of the total emission in active regions (ARs). Is this cooling pattern a common property of AR coronal plasma, or does it only occur in unique circumstances, locations, and times? The new Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA) data provide a wonderful opportunity to answer this question systematically for an entire AR. We measure the time lag between pairs of SDO/AIA EUV channels using 24 hr of images of AR 11082 observed on 2010 June 19. We find that there is a time-lag signal consistent with cooling plasma, just as is usually found for loops, throughout the AR including the diffuse emission between loops for the entire 24 hr duration. The pattern persists consistently for all channel pairs and choice of window length within the 24 hr time period, giving us confidence that the plasma is cooling from temperatures of greater than 3 MK, and sometimes exceeding 7 MK, down to temperatures lower than {approx}0.8 MK. This suggests that the bulk of the emitting coronal plasma in this AR is not steady; rather, it is dynamic and constantly evolving. These measurements provide crucial constraints on any model which seeks to describe coronal heating.

  20. Trend and interannual variability of summer precipitation and the atmospheric water vapor convergence in the Arctic circumpolar region

    NASA Astrophysics Data System (ADS)

    Hiyama, T.; Fujinami, H.; Oshima, K.

    2014-12-01

    This study investigated trend and interannual variability of summer (June, July and August) precipitation and the atmospheric water vapor convergence in the Arctic circumpolar region, with an emphasis on recent increase of those around the Lena river basin in eastern Siberia. Data used in this study are an archived precipitation data (PREC/L) and atmospheric re-analysis data (JRA-25, JRA-55). Previous studies have revealed a negative correlation in the summer atmospheric circulation pattern between the Lena and Ob river basins. However little is known about the atmospheric water cycles in the Arctic circumpolar region, including the Mackenzie river basin. Hence we compared the trend and interannual variability of summer precipitation and the atmospheric water vapor convergence in three large North Eurasian river (Lena, Yenisei, and Ob) basins together with the Mackenzie basin. The analyzed results are as follows. 1) In the highest five-year summer precipitation in the Lena river basin during the period 1958 to 2012, the center of the cyclonic circulation shifted to the east, from the Kara and Barents Seas over the region across the Yenisei and Lena. In the years, significant cyclonic deviation was present. The deviation distribution of the height field and the atmospheric water vapor flux from the west to the Lena river basin were significantly increased, so as to form a positive deviation of summer precipitation. 2) Significant increases (positive trend) in the summer precipitation were detected from 1984 to 2011 in the Lena, Yenisei, and the Mackenzie river basins. However, summer precipitation showed significant decreases (negative trend) over Mongolia and Europe/Russia. This was because anticyclones dominated in these regions. 3) A significant enhancement of cyclonic circulation was detected from 2005 to 2008 on the Eurasian side of the Arctic Ocean. However, anticyclones appeared over Mongolia. These probably increased the atmospheric water vapor convergence over the Lena river basin in this period. 4) A significant positive correlation in the summer precipitation appeared from around 1995 to 2005 between the Lena and Yenisei river basins. On the contrary, the negative correlation between the Lena and Ob river basins became unclear from 1993.

  1. Atmospheric response in aurora experiment: Observations of E and F region neutral winds in a region of postmidnight diffuse aurora

    NASA Technical Reports Server (NTRS)

    Larsen, M. F.; Marshall, T. R.; Mikkelsen, I. S.; Emery, B. A.; Christensen, A.; Kayser, D.; Hecht, J.; Lyons, L.; Walterscheid, R.

    1995-01-01

    The goal of the Atmospheric Response in Aurora (ARIA) experiment carried out at Poker Flat, Alaska, on March 3, 1992, was to determine the response of the neutral atmosphere to the long-lived, large-scale forcing that is characteristic of the diffuse aurora in the post midnight sector. A combination of chemical release rocket wind measurements, instrumented rocket composition measurements, and ground-based optical measurements were used to characterize the response of the neutral atmosphere. The rocket measurements were made at the end of a 90-min period of strong Joule heating. We focus on the neutral wind measurements made with the rocket. The forcing was determined by running the assimilated mapping of ionospheric electrodynamics (AMIE) analysis procedure developed at the National Center for Atmospheric Research. The winds expected at the latitude and longitude of the experiment were calculated using the spectral thermospheric general circulation model developed at the Danish Meteorological Institute. Comparisons of the observations and the model suggest that the neutral winds responded strongly in two height ranges. An eastward wind perturbation of approximately 100 m/s developed between 140 and 200 km altitude with a peak near 160 km. A southwestward wind with peak magnitude of approximately 150 m/s developed near 115 km altitude. The large amplitude winds at the lower altitude are particularly surprising. They appear to be associated with the upward propagating semidiurnal tide. However, the amplitude is much larger than predicted by any of the tidal models, and the shear found just below the peak in the winds was nominally unstable with a Richardson number of approximately 0.08.

  2. Influence of elevated atmospheric CO2 and tillage practice on rainfall simulation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    No work has investigated whether increasing atmospheric CO2 concentration will impact sediment loss in agricultural systems. Rainfall simulation was conducted following a 10-year study investigating the effects of atmospheric CO2 level (ambient and twice ambient) in two cropping systems (conventiona...

  3. Regional and historical variation in the nitrogen content of Racomitrium lanuginosum in Britain in relation to atmospheric nitrogen deposition.

    PubMed

    Baddeley, J A; Thompson, D B; Lee, J A

    1994-01-01

    The moss Racomitrium lanuginosum (Hedw.) Brid. is an important component of the drier parts of ombrotrophic mires and montane heaths in north-western Britain. The extent and quality of the montane heaths dominated by R. lanuginosum has declined in recent decades, perhaps in part due to the effects of acidic deposition at high elevations. This paper examines the effect of atmospheric nitrogen deposition, which has increased during this century, on the nitrogen content of R. lanuginosum in Britain. The nitrogen content of the moss reflects the magnitude of the atmospheric supply being least in north-western Scotland and greatest (as much as six-fold greater) near to urban centres in northern England. This regional difference was less marked (only approx. two-fold) during the 19th century (as revealed from the analysis of herbarium specimens) when nitrogen concentrations were appreciably lower. Transplant studies both between regions and between sites within a mountain system demonstrated the importance of atmospheric deposition in determining the tissue nitrogen concentration of the moss. The results are discussed in relation to the potential importance of the enhanced atmospheric nitrogen supply to the normally nitrogen-impoverished montane heaths, and to the growth and persistence of the moss. PMID:15091715

  4. An analysis of region-of-influence methods for flood regionalization in the Gulf-Atlantic Rolling Plains

    USGS Publications Warehouse

    Eng, K.; Tasker, Gary D.; Milly, P.C.D.

    2005-01-01

    Region-of-influence (RoI) approaches for estimating streamflow characteristics at ungaged sites were applied and evaluated in a case study of the 50-year peak discharge in the Gulf-Atlantic Rolling Plains of the southeastern United States. Linear regression against basin characteristics was performed for each ungaged site considered based on data from a region of influence containing the n closest gages in predictor variable (PRoI) or geographic (GRoI) space. Augmentation of this count based cutoff by a distance based cutoff also was considered. Prediction errors were evaluated for an independent (split-sampled) dataset. For the dataset and metrics considered here: (1) for either PRoI or GRoI, optimal results were found when the simpler count based cutoff, rather than the distance augmented cutoff, was used; (2) GRoI produced lower error than PRoI when applied indiscriminately over the entire study region; (3) PRoI performance improved considerably when RoI was restricted to predefined geographic subregions.

  5. Do atmospheric teleconnection patterns influence rainfall erosivity? A study of NAO, MO and WeMO in NE Spain, 1955-2006

    NASA Astrophysics Data System (ADS)

    Angulo-Martínez, Marta; Beguería, Santiago

    2012-07-01

    SummaryRainfall erosivity is the ability of precipitation to erode soil. Raindrops impact on the surface—rainsplash—represents an important mechanism of soil particles detachment. If the soil is not perfectly flat rainsplash will also produce the movement of soil particles down the slope due to diffusion. But even in the case of flat soils the detached particles will be available for transport by other erosion agents such as surface runoff. Despite its importance as fundamental erosion process very few studies have addressed the climatology of rainfall erosivity. It is known fact rainfall erosivity in long term (e.g., cumulative annual values) is determined by a few number of heavy events. This study analyses the interannual variability of daily rainfall erosivity in NE Spain during the period 1955-2006, and its connection with atmospheric circulation patterns influencing rainfall in the region, namely the North Atlantic Oscillation (NAO), the Mediterranean Oscillation (MO) and the Western Mediterranean Oscillation (WeMO). It is found that the erosive power of rainfall is stronger during negative phases of the three atmospheric circulation indices, and weaker during positive conditions. Daily rainfall erosivity series were adjusted to a Generalized Pareto probability distribution for positive and negative days of the atmospheric circulation indices, for assessing their effects on rainfall erosivity extreme events. Results showed higher values expected for a given return period in most of the area under negative conditions of all indices, especially at the Mediterranean coast. Overall, MO and WeMO showed the strongest influence on daily rainfall erosivity extremes. These findings would be useful in the implementation of soil conservation strategies.

  6. Localized Internal Gravity Waves Breaking Region and its Implications for Middle Atmospheric Circulation and Stratosphere-Troposphere Exchange

    NASA Astrophysics Data System (ADS)

    Šácha, Petr; Pišoft, Petr; Kucha?, Aleš; Lilienthal, Friederike; Jacobi, Christoph

    2015-04-01

    Internal gravity waves are widely recognized to contribute significantly to the energy and angular momentum transport. They play significant role in affecting many of the middle atmospheric phenomena (like QBO or Brewer-Dobson circulation). Using the GPS RO density profiles, we have discovered a localized area of enhanced IGW activity and breaking in the lower stratosphere of Eastern Asia/North-western Pacific region. Using a mechanistic model for the middle atmosphere, 3D EP flux and residual circulation diagnostics, we investigate longitudinal variability of the Brewer-Dobson circulation and a hypothesis of its enhanced branch in this region. Further, we study possible formation and propagation directions of planetary waves caused by such a localized forcing and discuss the consequences for the stratosphere-troposphere exchange and polar vortex stability.

  7. Global, Regional and Local Influences on Adult Literacy Policy in England

    ERIC Educational Resources Information Center

    Hamilton, Mary

    2014-01-01

    This paper explores the relationship between global, regional and local influences on adult literacy policy and practice in the UK through a discourse analysis of policy-related texts. The analysis is framed by theoretical perspectives from literacy studies and socio-material theory. The paper identifies a number of specific features in the UK…

  8. NAO influence on net sea ice production and exchanges in the Arctic region: a numerical study

    E-print Network

    Hu, Aixue

    NAO influence on net sea ice production and exchanges in the Arctic region: a numerical study Aixue The variability of net sea ice production and sea ice exchange between the Arctic and its adjacent seas are studied, using a coupled sea ice-ocean general circulation model. The wind driven divergence (or ice flux

  9. INFLUENCE OF BED-REGION STOICHIOMETRY ON NITRIC OXIDE FORMATION IN FIXED-BED COAL COMBUSTION

    EPA Science Inventory

    The article describes the use of a 15.3 x 25.4 cm thick bed reactor with refractory walls to investigate the influence of bed-region (first-stage) stoichiometry on fuel nitrogen evolution and reaction in coal-fired mass-burning stokers. The combustor operated in a batch mode prov...

  10. Simulating summertime rainfall variability in the North American monsoon region: The influence of convection and radiation

    E-print Network

    Small, Eric

    Simulating summertime rainfall variability in the North American monsoon region: The influence) and rainfall (CPC and CMAP). Differences in simulated rainfall produced by the various combinations of schema and magnitudes of rainfall, including intraseasonal variations and the differences between the wet and dry year

  11. Regional Variation of Climatic Influences on West Nile Virus Outbreaks in the United States

    PubMed Central

    Wimberly, Michael C.; Lamsal, Aashis; Giacomo, Paolla; Chuang, Ting-Wu

    2014-01-01

    The national resurgence of human West Nile virus (WNV) disease in 2012 raised questions about the factors responsible for WNV outbreaks. Interannual climatic variations may influence WNV amplification and transmission to humans through multiple pathways, including mosquito breeding habitats, gonotrophic cycles, extrinsic incubation, avian communities, and human behavior. We examined the influences of temperature and precipitation anomalies on interannual variation in human WNV cases in three regions of the United States. There were consistent positive influences of winter temperatures, weaker and more variable positive effects of spring and summer temperatures, and highly variable precipitation effects that ranged from positive to negative. The overwintering period may be a particularly important climatic constraint on the dynamics of WNV in cold-temperate regions of North America. Geographic differences in the seasonal timing and relative importance of climatic drivers of WNV risk likely reflect underlying variability in key ecological and social characteristics. PMID:25092814

  12. Regional variation of climatic influences on West Nile virus outbreaks in the United States.

    PubMed

    Wimberly, Michael C; Lamsal, Aashis; Giacomo, Paolla; Chuang, Ting-Wu

    2014-10-01

    The national resurgence of human West Nile virus (WNV) disease in 2012 raised questions about the factors responsible for WNV outbreaks. Interannual climatic variations may influence WNV amplification and transmission to humans through multiple pathways, including mosquito breeding habitats, gonotrophic cycles, extrinsic incubation, avian communities, and human behavior. We examined the influences of temperature and precipitation anomalies on interannual variation in human WNV cases in three regions of the United States. There were consistent positive influences of winter temperatures, weaker and more variable positive effects of spring and summer temperatures, and highly variable precipitation effects that ranged from positive to negative. The overwintering period may be a particularly important climatic constraint on the dynamics of WNV in cold-temperate regions of North America. Geographic differences in the seasonal timing and relative importance of climatic drivers of WNV risk likely reflect underlying variability in key ecological and social characteristics. PMID:25092814

  13. 41Name ________________________________ The Plasmasphere is a region of Earth's atmosphere above the ionosphere, and

    E-print Network

    the ionosphere, and extending over 15,000 kilometers into space. The Space Shuttle and the International Space's atmosphere above the ionosphere, and extending over 15,000 kilometers into space. The Space Shuttle

  14. Lagrangian methods for climatological analysis of regional atmospheric transport with an emphasis on Texas ozone exceedances 

    E-print Network

    Dexheimer, Darielle Nicole

    2004-11-15

    A quantitative climatology of atmospheric transport in Texas is developed using previously described Lagrangian trajectory methods (Rogers and Bowman, 2001; Bowman and Carrie, 2002). The trajectories are computed using ...

  15. Anthropogenic Influence on Secondary Aerosol Formation and Total Water-Soluble Carbon on Atmospheric Particles

    NASA Astrophysics Data System (ADS)

    Gioda, Adriana; Mateus, Vinicius; Monteiro, Isabela; Taira, Fabio; Esteves, Veronica; Saint'Pierre, Tatiana

    2013-04-01

    On a global scale, the atmosphere is an important source of nutrients, as well as pollutants, because of its interfaces with soil and water. Important compounds in the gaseous phase are in both organic and inorganic forms, such as organic acids, nitrogen, sulfur and chloride. In spite of the species in gas form, a huge number of process, anthropogenic and natural, are able to form aerosols, which may be transported over long distances. Sulfates e nitrates are responsible for rain acidity; they may also increase the solubility of organic compounds and metals making them more bioavailable, and also can act as cloud condensation nuclei (CCN). Aerosol samples (PM2.5) were collected in a rural and industrial area in Rio de Janeiro, Brazil, in order to quantify chemical species and evaluate anthropogenic influences in secondary aerosol formation and organic compounds. Samples were collected during 24 h every six days using a high-volume sampler from August 2010 to July 2011. The aerosol mass was determined by Gravimetry. The water-soluble ionic composition (WSIC) was obtained by Ion Chromatography in order to determine the major anions (NO3-, SO4= and Cl-); total water-soluble carbon (TWSC) was determined by a TOC analyzer. The average aerosol (PM2.5) concentrations ranged from 1 to 43 ug/m3 in the industrial site and from 4 to 35 ug/m3 in the rural area. Regarding anions, the highest concentrations were measured for SO42- (10.6 ?g/m3-12.6 ?g/m3); where the lowest value was found in the rural site and the highest in the industrial. The concentrations for NO3- and Cl- ranged from 4.2 ?g/m3 to 9.3 ?g/m3 and 3.1 ?g/m3 to 6.4 ?g /m3, respectively. Sulfate was the major species and, like nitrate, it is related to photooxidation in the atmosphere. Interestingly sulfate concentrations were higher during the dry period and could be related to photochemistry activity. The correlations between nitrate and non-sea-salt sulfate were weak, suggesting different sources for these species. The secondary aerosol represented an important fraction of total compounds in PM2.5 ranged from 16 to 18% for (NH4)2SO4 and 6 to 8% for NH4NO3. The values for TWSC ranged from 0.28 to 6.35 ?g/m3 in the industrial area and 0.12 to 7.49 ?g/m3 for rural area. The similarity between the areas regarding secondary aerosols formation and water-soluble carbon compounds is probably due to the particle size.

  16. Large-scale atmospheric processes in the Arctic region reproduced by Sl-AV model and reanalysis data

    NASA Astrophysics Data System (ADS)

    Kulikova, Irina; Kruglova, Ekaterina; Khan, Valentina; Kiktev, Dmitry; Tischenko, Vladimir

    2015-04-01

    The variability of large-scale atmospheric processes in the Arctic region was analyzed on the base of the NCEP/DOE reanalysis data and seasonal hindcasts from global semi-Lagrangian model (SL-AV), developed in collaboration of Hydrometeorological Centre of Russia with Institute of Numerical Mathematics. Using the factor analysis it was shown that the model reproduces well the first major variability modes to explain 85-90% of the accumulated dispersion. Teleconnection indices as the quantitative characteristics of low-frequency variability are used to identify zonal and meridional flow regimes. Composite maps indicating the spatial distribution of anomalies of the main meteorological variables (500 hPa geopotential height, the sea level atmospheric pressure, the temperature at 850 hPa, 2m air temperature, precipitation, zonal and meridional wind component) for positive and negative phases of each index of atmospheric circulation are created. Average values of composite maps are accompanied with their statistical significance assessed using the "bootstrap" technique. Main characteristics of field configuration in Arctic region of cited above meteorological parameters corresponding to positive and negative phases of circulation indices are analyzed and discussed. Ability of SL-AV model to reproduce these characteristics at monthly and seasonal time scale is discussed as well. Results of this study are aimed to improve the quality of long-range forecasts and increase the "limit of predictability" and can be useful in the practice to develop monthly and seasonal weather forecasts for the Arctic region.

  17. A spatially explicit multi-isotope approach to map influence regions of plant-plant interactions after exotic plant invasion

    NASA Astrophysics Data System (ADS)

    Hellmann, Christine; Oldeland, Jens; Werner, Christiane

    2015-04-01

    Exotic plant invasions impose profound alterations to native ecosystems, including changes of water, carbon and nutrient cycles. However, explicitly quantifying these impacts remains a challenge. Stable isotopes, by providing natural tracers of biogeochemical processes, can help to identify and measure such alterations in space and time. Recently, ?15N isoscapes, i.e. spatially continuous representations of isotopic values, derived from native plant foliage, enabled to accurately trace nitrogen introduced by the N2-fixing invasive Acacia longifolia into a native Portuguese dune system. It could be shown that the area of the system which was altered by the invasive species exceeded the area which was covered by the invader by far. But still, definition of clear regions of influence is to some extent ambiguous. Here, we present an approach using multiple isoscapes derived from measured foliar ?13C and ?15N values of a native, non-fixing species, Corema album. By clustering isotopic information, we obtained an objective classification of the study area. Properties and spatial position of clusters could be interpreted to distinguish areas that were or were not influenced by A. longifolia. Spatial clusters at locations where A. longifolia was present had ?15N values that were enriched, i.e. close to the atmospheric signal of 0 o compared to the depleted values of the uninvaded system (ca. -11 o). Furthermore, C. album individuals in these clusters were characterized by higher foliar N content and enriched ?13C. These results indicate that the N2-fixing A. longifolia added nitrogen to the system which originated from the atmosphere and was used by the native C. album, inducing functional changes, i.e. an increase in WUE. Additionally, clusters were identified that were presumably determined by inherent properties of the native system. Thus, combining isotope ecology with geostatistical methods is a promising approach for mapping regions of influence in multi-isotope isoscapes which may be relevant not only to detect ecological boundaries within the context of exotic plant invasion but for plant-plant-interactions and small-scale variability of biotic and abiotic conditions in general.

  18. Influence of small-scale North Atlantic sea surface temperature patterns on the marine boundary layer and free troposphere: a study using the atmospheric ARPEGE model

    NASA Astrophysics Data System (ADS)

    Piazza, Marie; Terray, Laurent; Boé, Julien; Maisonnave, Eric; Sanchez-Gomez, Emilia

    2015-06-01

    A high-resolution global atmospheric model is used to investigate the influence of the representation of small-scale North Atlantic sea surface temperature (SST) patterns on the atmosphere during boreal winter. Two ensembles of forced simulations are performed and compared. In the first ensemble (HRES), the full spatial resolution of the SST is maintained while small-scale features are smoothed out in the Gulf Stream region for the second ensemble (SMTH). The model shows a reasonable climatology in term of large-scale circulation and air-sea interaction coefficient when compared to reanalyses and satellite observations, respectively. The impact of small-scale SST patterns as depicted by differences between HRES and SMTH shows a strong meso-scale local mean response in terms of surface heat fluxes, convective precipitation, and to a lesser extent cloudiness. The main mechanism behind these statistical differences is that of a simple hydrostatic pressure adjustment related to increased SST and marine atmospheric boundary layer temperature gradient along the North Atlantic SST front. The model response to small-scale SST patterns also includes remote large-scale effects: upper tropospheric winds show a decrease downstream of the eddy-driven jet maxima over the central North Atlantic, while the subtropical jet exhibits a significant northward shift in particular over the eastern Mediterranean region. Significant changes are simulated in regard to the North Atlantic storm track, such as a southward shift of the storm density off the coast of North America towards the maximum SST gradient. A storm density decrease is also depicted over Greenland and the Nordic seas while a significant increase is seen over the northern part of the Mediterranean basin. Changes in Rossby wave breaking frequencies and weather regimes spatial patterns are shown to be associated to the jets and storm track changes.

  19. Coupled ocean-atmosphere surface variability and its climate impacts in the tropical Atlantic region

    NASA Astrophysics Data System (ADS)

    Fontaine, B.; Janicot, Serge; Roucou, P.

    This study examines time evolution and statistical relationships involving the two leading ocean-atmosphere coupled modes of variability in the tropical Atlantic and some climate anomalies over the tropical 120°W-60°W region using selected historical files (75-y near global SSTs and precipitation over land), more recent observed data (30-y SST and pseudo wind stress in the tropical Atlantic) and reanalyses from the US National Centers for Environmental Prediction (NCEP/NCAR) reanalysis System on the period 1968-1997: surface air temperature, sea level pressure, moist static energy content at 850 hPa, precipitable water and precipitation. The first coupled mode detected through singular value decomposition of the SST and pseudo wind-stress data over the tropical Atlantic (30°N-20°S) expresses a modulation in the thermal transequatorial gradient of SST anomalies conducted by one month leading wind-stress anomalies mainly in the tropical north Atlantic during northern winter and fall. It features a slight dipole structure in the meridional plane. Its time variability is dominated by a quasi-decadal signal well observed in the last 20-30 ys and, when projected over longer-term SST data, in the 1920s and 1930s but with shorter periods. The second coupled mode is more confined to the south-equatorial tropical Atlantic in the northern summer and explains considerably less wind-stress/SST cross-covariance. Its time series features an interannual variability dominated by shorter frequencies with increased variance in the 1960s and 1970s before 1977. Correlations between these modes and the ENSO-like Nino3 index lead to decreasing amplitude of thermal anomalies in the tropical Atlantic during warm episodes in the Pacific. This could explain the nonstationarity of meridional anomaly gradients on seasonal and interannual time scales. Overall the relationships between the oceanic component of the coupled modes and the climate anomaly patterns denote thermodynamical processes at the ocean/atmosphere interface that create anomaly gradients in the meridional plane in a way which tends to alter the north-south movement of the seasonal cycle. This appears to be consistent with the intrinsic non-dipole character of the tropical Atlantic surface variability at the interannual time step and over the recent period, but produces abnormal amplitude and/or delayed excursions of the intertropical convergence zone (ITCZ). Connections with continental rainfall are approached through three (NCEP/NCAR and observed) rainfall indexes over the Nordeste region in Brazil, and the Guinea and Sahel zones in West Africa. These indices appear to be significantly linked to the SST component of the coupled modes only when the two Atlantic modes+the ENSO-like Nino3 index are taken into account in the regressions. This suggests that thermal forcing of continental rainfall is particularly sensitive to the linear combinations of some basic SST patterns, in particular to those that create meridional thermal gradients. The first mode in the Atlantic is associated with transequatorial pressure, moist static energy and precipitable water anomaly patterns which can explain abnormal location of the ITCZ particularly in northern winter, and hence rainfall variations in Nordeste. The second mode is more associated with in-phase variations of the same variables near the southern edge of the ITCZ, particularly in the Gulf of Guinea during the northern spring and winter. It is primarily linked to the amplitude and annual phase of the ITCZ excursions and thus to rainfall variations in Guinea. Connections with Sahel rainfall are less clear due to the difficulty for the model to correctly capture interannual variability over that region but the second Atlantic mode and the ENSO-like Pacific variability are clearly involved in the Sahel climate interannual fluctuations: anomalous dry (wet) situations tend to occur when warmer (cooler) waters are present in the eastern Pacific and the gulf of Guinea in northern summer which contribute to create a northward (southward) transequ

  20. On the local and regional influence on ground-level ozone concentrations in Hong Kong.

    PubMed

    So, K L; Wang, T

    2003-01-01

    Hong Kong is a densely populated city situated in the fast developing Pearl River Delta of southern China. In this study, the recent data on ozone (O3) and related air pollutants obtained at three sites in Hong Kong are analyzed to show the variations of O3 in urban, sub-urban and rural areas and the possible regional influences. Highest monthly averaged O3 was found at a northeastern rural site and lowest O3 level was observed at an urban site. The levels of NOx, CO, SO2 and PM10 showed a different spatial pattern with the highest level in the urban site and lowest at the rural site. Analysis of chemical species ratios such as SO2/NOx and CO/NOx indicated that the sites were under the influences of local and regional emissions to varying extents reflecting the characteristics of emission sources surround the respective sites. Seasonal pattern of O3 is examined. Low O3 level was found in summer and elevated levels occurred in autumn and spring. The latter appears different from the previous result obtained in 1996 indicating a single maximum occurring in autumn. Principal component analysis was used to further elucidate the relationships of air pollutants at each site. As expected, the O3 variation in the northeastern rural area was largely determined by regional chemical and transport processes, while the O3 variability at the southwestern suburban and urban sites were more influenced by local emissions. Despite the large difference in O3 levels across the sites, total potential ozone (O3+NO2) showed little variability. Cases of high O3 episodes were presented and elevated O3 levels were formed under the influence of tropical cyclone bringing in conditions of intense sunlight, high temperature and light winds. Elevated O3 levels were also found to correlate with enhanced ratio of SO2 to NOx, suggesting influence of regional emissions from the adjacent Pearl River Delta region. PMID:12628210

  1. Mutual interaction of soil moisture state and atmospheric processes

    Microsoft Academic Search

    Dara Entekhabi; Ignacio Rodriguez-Iturbe; Fabio Castelli

    1996-01-01

    The purpose of this paper is to outline the pathways through which soil moisture and meteorological phenomena mutually influence one another at local, regional and global scales. This constitutes two-way land-atmosphere interaction, as meteorological phenomena both act as the forcing and react to the forcing by the soil moisture state. Land surface modification of the atmospheric environment and the atmospheric

  2. [Influence of elevated atmospheric CO2 on rhizosphere microbes and arbuscular mycorrhizae].

    PubMed

    Chen, Jing; Chen, Xin; Tang, Jianjun

    2004-12-01

    The changes of microbial communities in rhizosphere and the formation of mycorrhizae play an important role in affecting the dynamics of plant communities and terrestrial ecosystems. This paper summarized and discussed the effects of elevated atmospheric CO2 on them. Under elevated atmospheric CO2, the carbohydrates accumulated in root systems increased, and the rhizospheric environment and its microbial communities as well as the formation of mycorrhizae changed. It is suggested that the researches in the future should be focused on the effects of rhizosphere microbes and arbuscular mycorrhizae on regulating the carbon dynamics of plant communities and terrestrial ecosystems under elevated atmospheric CO2. PMID:15825462

  3. The influence of the growth of the Dallas/Fort Worth (DFW) Metroplex on regional precipitation patterns 

    E-print Network

    Nordfelt, Anna Marie

    2009-05-15

    regions. Previous research has shown that cities can influence regional precipitation patterns. This is a result of many factors such as: increased heating and lifting caused by the urban heat island effect (UHI), increased pollution and aerosols...

  4. The Influence of Hepatitis C Virus Genetic Region on Phylogenetic Clustering Analysis

    PubMed Central

    Lamoury, François M. J.; Jacka, Brendan; Bartlett, Sofia; Bull, Rowena A.; Wong, Arthur; Amin, Janaki; Schinkel, Janke; Poon, Art F.; Matthews, Gail V.; Grebely, Jason; Dore, Gregory J.; Applegate, Tanya L.

    2015-01-01

    Sequencing is important for understanding the molecular epidemiology and viral evolution of hepatitis C virus (HCV) infection. To date, there is little standardisation among sequencing protocols, in-part due to the high genetic diversity that is observed within HCV. This study aimed to develop a novel, practical sequencing protocol that covered both conserved and variable regions of the viral genome and assess the influence of each subregion, sequence concatenation and unrelated reference sequences on phylogenetic clustering analysis. The Core to the hypervariable region 1 (HVR1) of envelope-2 (E2) and non-structural-5B (NS5B) regions of the HCV genome were amplified and sequenced from participants from the Australian Trial in Acute Hepatitis C (ATAHC), a prospective study of the natural history and treatment of recent HCV infection. Phylogenetic trees were constructed using a general time-reversible substitution model and sensitivity analyses were completed for every subregion. Pairwise distance, genetic distance and bootstrap support were computed to assess the impact of HCV region on clustering results as measured by the identification and percentage of participants falling within all clusters, cluster size, average patristic distance, and bootstrap value. The Robinson-Foulds metrics was also used to compare phylogenetic trees among the different HCV regions. Our results demonstrated that the genomic region of HCV analysed influenced phylogenetic tree topology and clustering results. The HCV Core region alone was not suitable for clustering analysis; NS5B concatenation, the inclusion of reference sequences and removal of HVR1 all influenced clustering outcome. The Core-E2 region, which represented the highest genetic diversity and longest sequence length in this study, provides an ideal method for clustering analysis to address a range of molecular epidemiological questions. PMID:26192190

  5. Coupling of a regional atmospheric model (RegCM3) and a regional oceanic model (FVCOM) over the maritime continent

    E-print Network

    Wei, Jun

    Climatological high resolution coupled climate model simulations for the maritime continent have been carried out using the regional climate model (RegCM) version 3 and the finite volume coastal ocean model (FVCOM) ...

  6. Utilization by the growing-finishing pig of wet wheat stored under inter gas atmosphere: Influence of moisture content and grinding fineness

    E-print Network

    Paris-Sud XI, Université de

    Utilization by the growing-finishing pig of wet wheat stored under inter gas atmosphere: Influence to study the utilization by growing- finishing pigs (between 25 and 103 kg) of ground wheat stored in bunker silo under inert gas atmosphere. In each trial, 4 diets were compared : moist wheat (20 p. 100

  7. CO 2 line mixing in MIPAS limb emission spectra and its influence on retrieval of atmospheric parameters

    Microsoft Academic Search

    B. Funke; G. P. Stiller; T. Von Clarmann; G. Echle; H. Fischer

    1998-01-01

    Aboard the European ENVISAT polar platform, the MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) i.r. spectrometer will scan across the limb in order to record high resolution emission spectra. In the course of the definition of micro-windows for retrieval of line of sight, temperature and trace constituents, the spectral and altitudinal regions where CO2 Q-branch line mixing has to be

  8. Non-linear Ice Sheet influence during deglaciation and its impact on the evolution of atmospheric teleconnection patterns

    NASA Astrophysics Data System (ADS)

    Dietrich, Stephan; Wassenburg, Jasper; Wei, Wei; Lohmann, Gerrit; Jens, Fohlmeister; Adrian, Immenhauser

    2013-04-01

    During present conditions atmospheric teleconnections such as the Arctic Oscillation/North Atlantic Oscillation (AO/NAO) have a major impact on Northern Hemispheric climate. However, the Early Holocene is characterized by the presence and melting of the Laurentide Ice Sheet (LIS) leading to a different background climate in comparison to today. Here we investigate the climate evolution during the early (9 ka BP, including LIS and melt water), mid (6 ka BP) and late Holocene (pre-industrial conditions) focussing on the mechanisms and feedbacks during deglaciation by applying the state-of-the-art earth system model COSMOS. A special interest is set on the evolution of atmospheric teleconnection patterns such as the AO/NAO and the Atlantic Multidecadal Oscillation (AMO) that have a major influence on North Atlantic/European climate. The evolution and relative importance of these oscillations throughout the Holocene, however, is still largely unknown. We demonstrate that North Atlantic/European climate is affected by a shift from a more ocean-ice-dominated climate during approx. 9 ka towards a more atmosphere-dominated one during the mid to late Holocene. To isolate the contributions of the presence of the LIS and the melt water we run four different model simulations for the early Holocene sensitivity study (a standard configuration only forced with green house gases and orbital parameters, one with the additional LIS topography, one with a melt water flux of 0.09 Sv, and a fourth that combines all the external forcings). The model results show that the influence of the LIS and its melt water contribution lead to a strong non-linear cooling of surface air temperatures during deglaciation. This synergetic influence of the Laurentide Ice Sheet strengthens the effect of melting on ocean circulation during the early Holocene. The severe colder background climate during deglaciation leads to a more vulnerable ocean circulation in terms of the Atlantic Meridional Overturning Circulation. Changes of this circulation are known to affect the atmosphere as well via mechanisms like the AMO. The corresponding sea level pressure pattern is an atmospheric response to oceanic thermal forcing, which results from variations of the thermohaline circulation. The AMO has a potential to influence the shape of the subtropical high and to shift AO/NAO pressure centres towards easterly and north-easterly directions during the early Holocene. This non-stationary behaviour of the AO/NAO due to deglaciation processes is also demonstrated by a novel set of North Atlantic/European speleothem records that show an active AO/NAO all over the Holocene.

  9. Increasing Mississippi river discharge throughout the 21st century influenced by changes in climate, land use, and atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Tao, Bo; Tian, Hanqin; Ren, Wei; Yang, Jia; Yang, Qichun; He, Ruoying; Cai, Weijun; Lohrenz, Steven

    2014-07-01

    Previous studies have demonstrated that changes in temperature and precipitation (hereafter climate change) would influence river discharge, but the relative importance of climate change, land use, and elevated atmospheric CO2 have not yet been fully investigated. A process-based projection for the Mississippi River basin suggests that river discharge would be substantially enhanced (10.7-59.8%) by the 2090s compared to the recent decade (2000s), although large discrepancies exist among different climate, atmospheric CO2, and land use change scenarios. Our factorial analyses further indicate that the combined effects of land use change and human-induced atmospheric CO2 elevation on river discharge would outweigh climate change effect under the high-emission scenario (A2) of the Intergovernmental Panel for Climate Change, while climate change would still play the dominant role under the low-emission scenario (B1). This study highlights the important role of anthropogenic factors in influencing future hydrological processes and water resources.

  10. Atmospheric forcing intensifies the effects of regional ocean warming on reef-scale temperature anomalies during a coral bleaching event

    NASA Astrophysics Data System (ADS)

    Zhang, Zhenlin; Falter, James; Lowe, Ryan; Ivey, Greg; McCulloch, Malcolm

    2013-09-01

    We investigate how local atmospheric conditions and hydrodynamic forcing contributed to local variations in water temperature within a fringing coral reef-lagoon system during the peak of a marine heat wave in 2010-2011 that caused mass coral bleaching across Western Australia. A three-dimensional circulation model Regional Ocean Modeling System (ROMS) with a built-in air-sea heat flux exchange module Coupled Ocean Atmosphere Experiment (COARE) was coupled with a spectral wave model Simulating Waves Nearshore (SWAN) to resolve the surface heat exchange and wave-driven reef circulation in Coral Bay, Ningaloo Reef. Using realistic oceanic and atmospheric forcing, the model predictions were in good agreement with measured time series of water temperature at various locations in the coral reef system during the bleaching event. Through a series of sensitivity analyses, we found that the difference in temperature between the reef and surrounding offshore waters (?T) was predominantly a function of both the daily mean net heat flux (Qnet>¯) and residence time, whereas diurnal variations in reef water temperature were dependent on the diurnal fluctuation in the net heat flux. We found that reef temperatures were substantially higher than offshore in the inner lagoon under normal weather conditions and over the entire reef domain under more extreme weather conditions (0.7°C-1.5°C). Although these temperature elevations were still less than that caused by the regional ocean warming (2°C-3°C), the arrival of peak seasonal temperatures in the summer of 2010-2011 (when net atmospheric heat fluxes were positive and abnormally high) caused substantially higher thermal stresses than would have otherwise occurred if offshore temperatures had reached their normal seasonal maxima in autumn (when net atmospheric heat fluxes were negative or cooling). Therefore, the degree heating weeks calculated based on offshore temperature substantially underestimated the thermal stresses experienced by the reef in the period leading up to the observed bleaching event (3 versus 11°C-weeks).

  11. Influence of Modified Atmosphere Storage on Aflatoxin Production in High Moisture Corn

    PubMed Central

    Wilson, David M.; Jay, Edward

    1975-01-01

    Samples of freshly harvested corn and remoistened corn were inoculated with Aspergillus flavus and stored for 4 weeks at about 27 C in air and three modified atmospheres. Aflatoxins and fat acidity were determined weekly. Corn stored in the modified atmospheres did not accumulate over 15 ?g of aflatoxin B1 per kg and 20 ?g of total aflatoxins per kg. Corn from the high CO2 treatment (61.7% CO2, 8.7% O2, and 29.6% N2) was visibly molded at 4 weeks and had a higher fat acidity than the other treatments. In the N2 (99.7% N2 and 0.3% O2) and controlled atmosphere (13.5% CO2, 0.5% O2, 84.8% N2) treatments, a fermentation-like odor was detected. When the corn was removed from the modified atmospheres it deteriorated rapidly and was soon contaminated with aflatoxins. PMID:803817

  12. Identification of potential regional sources of atmospheric total gaseous mercury in Windsor, Ontario, Canada using hybrid receptor modeling

    NASA Astrophysics Data System (ADS)

    Xu, X.; Akhtar, U. S.

    2010-08-01

    Windsor (Ontario, Canada) experiences trans-boundary air pollution as it is located on the border immediately downwind of industrialized regions of the United States of America. A study was conducted in 2007 to identify the potential regional sources of total gaseous mercury (TGM) and investigate the effects of regional sources and other factors on seasonal variability of TGM concentrations in Windsor. TGM concentration was measured at the University of Windsor campus using a Tekran® 2537A Hg vapour analyzer. An annual mean of 2.02±1.63 ng/m3 was observed in 2007. The average TGM concentration was high in the summer (2.48±2.68 ng/m3) and winter (2.17±2.01 ng/m3), compared to spring (1.88±0.78 ng/m3) and fall (1.76±0.58 ng/m3). Hybrid receptor modeling potential source contribution function (PSCF) was used by incorporating 72-h backward trajectories and measurements of TGM in Windsor. The results of PSCF were analyzed in conjunction with the Hg emissions inventory of North America (by state/province) to identify regions affecting Windsor. In addition to annual modeling, seasonal PSCF modeling was also conducted. The potential source region was identified between 24-61° N and 51-143° W. Annual PSCF modeling identified major sources southwest of Windsor, stretching from Ohio to Texas. The emissions inventory also supported the findings, as Hg emissions were high in those regions. Results of seasonal PSCF modeling were analyzed to find the combined effects of regional sources, meteorological conditions, and surface re-emissions, on seasonal variability of Hg concentrations. It was found that the summer and winter highs of atmospheric Hg can be attributed to areas where large numbers of coal fired power plants are located in the USA. Weak atmospheric dispersion due to low winds and high re-emission from surfaces due to higher temperatures also contributed to high concentrations in the summer. In the winter, the atmospheric removal of Hg was slow, but strong winds led to more dispersion, resulting in lower concentrations than the summer. Future studies could use smaller grid sizes and refined emission inventories, for more accurate analysis of source-receptor relationship of atmospheric Hg.

  13. Lower ionosphere monitoring by the South America VLF Network (SAVNET): C region occurrence and atmospheric temperature variability

    NASA Astrophysics Data System (ADS)

    Bertoni, Fernando Celso Perin; Raulin, Jean-Pierre; Gavilán, Hernán. Rivero; Kaufmann, Pierre; Rodriguez, Rodolfo; Clilverd, Mark; Cardenas, Jorge Samanes; Fernandez, Germán.

    2013-10-01

    profiles of phase measurements as observed on fixed VLF paths generally show a transient phase advance, followed by a phase delay, for about 90 min after sunrise hours. This is indicative of a reflecting ionospheric C region developing along the terminator line at an altitude below the normal D region. The suggested occurrence of a C region is consistent with rocket measurements made in the 1960s, showing a maximum of the electron density between 64 and 68 km, and by radio sounding in the 1980s. In order to correctly describe the properties of the phase effect associated with the presence of a C region, it is important to understand the subionospheric propagation characteristics of the VLF paths. In this paper, we analyze the variations presented by the temporal properties of the VLF narrowband phase effect and determined a parameter associated with the appearance of the C region at sunrise hours observed by receivers from the South America VLF Network. Periodic patterns emerge from the parameter curves. Two distinct temporal behavior regimes can be identified: one exhibiting slow variations between March and October, and another one exhibiting faster variations between October and March. Solar illumination conditions and the geometrical configuration of the VLF paths relative to the sunrise terminator partly explain the slow variation regime. During periods of faster variations, we have observed good association with atmospheric temperature variability found in the measurements of the Thermosphere Ionosphere Mesosphere Energetics and Dynamics and Sounding of the Atmosphere using Broadband Emission Radiometry satellite instrument, which we assume to be related to the winter anomaly atmospheric phenomenon. However, when comparing the parameter time series with temperature curves, no direct one-to-one correspondence was found for transient events.

  14. Influence of environmental moisture on atmospheric pressure plasma jet treatment of ultrahigh-modulus polyethylene fibers

    Microsoft Academic Search

    Y. Liu; H. Xu; L. Ge; C. Wang; L. Han; H. Yu; Y. Qiu

    2007-01-01

    One of the main differences between low-pressure and atmospheric-pressure plasma treatments is that there is little moisture involved in the low-pressure plasma treatment, although moisture could exist at the wall of the vacuum chamber or react with the substrate after plasma treatment, while in the atmospheric-pressure plasma treatment moisture exists not only in the environment but also in any hygroscopic

  15. The Influence of Shale Rock Fracturing Equipment Operation on Atmospheric Air Quality

    NASA Astrophysics Data System (ADS)

    Bogacki, Marek; Macuda, Jan

    2014-12-01

    The hydraulic fracturing jobs performed on shale rocks are connected with atmospheric emissions of dusts and exhaust gases from high-power motors supplying pump aggregates used for fracturing operations and from other technological devices. The total power of motors driving technological systems depends on the specific character of deposit and well and may range between a dozen to tens of thousands kW. An exemplary set of technological systems used for frac jobs is presented in figure 1. The following substances are emitted to the atmosphere during engine operation, e.g. nitrogen oxides (NOx), sulfur dioxide (SO2), carbon oxide (CO), dust PM10, ammonia, benzo(a)pyrene (B(a)P), benzene, toluene, xylene, formaldehyde, acetaldehyde, acrolein. As a consequence admissible concentrations of these substances in air can be exceeded. The influence of dust and gaseous emissions accompanying shale rock fracturing jobs is addressed in this paper. Model analyses were performed. An exemplary model of a process used for simulating propagation of atmospheric emissions in a specified calculation area (1,150 m × 1,150 m) were based on the analysis of hydraulic fracturing jobs performed in wells in Poland and abroad. For making calculations more actual, the model was located in the Gda?sk area and was ascribed its typical meteorological and orographic parameters. In the center of this area a rig site 150 m x 150 m was distinguished. The emission field was generated by 12 high-power engines supplying pump aggregates, 1680 kW each. The time of work of particular engines was established for 52 hrs (13 frac jobs, each lasting 4 hrs). It was assumed that all engines will operate simultaneously and using 100% of their power. Attention was paid to the correct modelling of the real emission field. Technical parameters of motors and the applied fuels were characterized. Emission indices were worked out by, e.g. U.S. Environmental Protection Agency or European Environment Agency. The calculations of air pollutions from analyzed motors were performed with a mathematical modelling method using Gaussian plum. The results of calculations could be used for evaluating spatial distribution of maximum 1 hour concentrations (S1), incidence of exceeding admissible 1 hour concentration values (P(D1)), percentile 99.8 or 99.726 from 1 hour concentrations and average concentrations (Sa) for selected most important for the air quality contaminants, i.e. NOx (as NO2), SO2, CO, PM10, benzo(a)pyrene, benzene, toluene, xylene, formaldehyde, acetaldehyde and acrolein. The results of calculated air concentrations of selected substances on the rig border are listed in table 9, whereas spatial distributions of NOx and PM10 concentrations in figures 3 to 8. The analysis of the obtained results did not reveal cases of exceeding Polish emission standards. However, nitrogen oxide (NOx) or dust PM10 can be expected to exceed these values, e.g. in a situation when the total power installed in motors driving technological systems in the course of hydraulic fracking will be higher than assumed in the analyses. The results of calculations show to a significant impact of nitrogen oxides (NOx) and dust PM10 emissions on air quality. The risk that emission standards are exceeded beyond the rig area is conditioned both by technological factors (total power of operating motors, parameters of combusted fuel, reduced emission technologies applied to engines, duration of frac jobs, etc.) and a number of external factors, e.g. meteorological and orographic factors or high level of emitted substances in air within the rig area. Proces hydraulicznego szczelinowania ska? ?upkowych wi??e si? z emisj? do powietrza zanieczyszcze? py?owo-gazowych z silników wysokopr??nych du?ej mocy nap?dzaj?cych agregaty pompowe do szczelinowania ska? oraz inne urz?dzenia technologiczne. ??czna moc silników nap?dzaj?cych urz?dzenia technologiczne uzale?niona jest od specyfiki z?o?a oraz specyfiki odwiertu i waha si? od kilkunastu do kilkudziesi?ciu tysi?cy kW. Przyk?adowy zestaw u

  16. Atmospheric numerical simulation of the aerosol microphysics and radiative effects in a regional biomass burning smoke plume in South America

    NASA Astrophysics Data System (ADS)

    Longo, K.; Freitas, S.; Silva Dias, M.; Silva Dias, P.; Chatfield, R.

    2003-04-01

    A study about the atmospheric transport of biomass burning emissions in the Amazon and the central of Brazil including its radiative effects is presented. The sources are spatially and temporally distributed and daily assimilated, according to the biomass burning spots defined by GOES-8 ABBA fire products. A fire smoke particles source parameterization, including aerosol particle concentration and optical properties, was used to build the initial smoke plumes associated with biomass burning in tropical forest and savanna. This study is carried out through a numerical simulation of the atmospheric motions using the atmospheric model RAMS "Regional Atmospheric Modeling System" and the coupled microphysics aerosol model CARMA "Community Aerosol &Radiation Model for Atmospheres". In this method the mass conservation equation and aerosol particle process, like nucleation, coagulation, condensation and dry deposition, are resolved for the biomass burning aerosol particles. The advection, in a resolved scale, and turbulent transport, in a sub-grid scale, are resolved using RAMS model parameterizations. A transport sub-grid parameterization, associated to deep and shallow cumulus convection, not explicitly resolved by the model due its low spatial resolution, is introduced. Also, a wet deposition term, coupled to the cumulus parameterization, is taken into account. The methodology is applied to a case study on August 2002 and the responses of the model to the presence of the aerosol particles in the atmosphere are explored. Also the comparison of the simulated smoke haze layer with MODIS products pointed out the usefulness of the sources emissions parameterization and the suitability of the aerosol process description presented here.

  17. Asteroid and comet impacts on Mars and their influence on atmospheric mass evolution and habitability.

    NASA Astrophysics Data System (ADS)

    Karatekin, Özgür

    2015-04-01

    Impacts by asteroids and comets could have significant affects on the habitability and atmospheric evolution of terrestrial planets by removing part of its atmosphere, by delivering into it material and volatiles. Large impacts could have repeatedly destroyed the existing biosphere, but in the mean time new subsurface habitats have likely formed from impact induced hydrothermal systems. Early in its history, Mars could have a much denser atmosphere and higher surface temperatures to sustain the presence of stable liquid water or saline solution at the surface, as suggested by several studies. The environmental effects of a period of impact bombardment on terrestrial planets remain poorly constrained. In this study we revisit the atmospheric loss and delivery of volatiles on Mars between the end of the Noachian and present using numerical models. Following an impact, the quantity of escaped atmosphere, as well as impactor and target materials can be estimated using numerical simulations. Studies on the atmospheric loss and delivery due to impacts differ sometimes by orders of magnitude, mainly due to different equation of state and dynamical models used. The hydrocode simulations designed to simulate a single impact are not suitable to study the cumulative effect of impact erosion and delivery in the long term due to their extremely high computation costs. Instead, empirical approximations based on hydrocode simulations have been used to estimate atmospheric evolution. Comparison between different hydrocode results and atmospheric mass evolution upon impacts based on empirical models will be presented using revised model parameters. In addition, different delivery and lost mechanisms including volcanic outgassing and non-thermal escape, can be taken into account to study various atmospheric evolution scenarios. Our results suggest that impacts alone can hardly remove a significant amount of atmospheric mass over this period. Contribution of additional factors such as outgassing and non- thermal escape processes can not explain neither the presence of surface pressure larger than few hundreds of mbars 3.9 Gyr ago. Based on extreme case scenarios, maximum surface pressures at the end of the Noachian, could be as much as 0.25 bar or 1.9 bar, with and without CO2 storage into carbonate reservoirs, respectively.

  18. An improved algorithm for extracting atmospheric motion vectors in cloud-free region from FY-2E thermal infrared imagery

    NASA Astrophysics Data System (ADS)

    Wang, Zhenhui; Zhang, Qing; Tang, Min; Zhao, Hang; Yang, Lu; Zhan, Yizhe

    2014-10-01

    Atmospheric motion vectors (AMV) in cloud-free region can not be obtained with current operational cloud-motion tracking and water-vapor channel algorithms. The motivation of this study is to introduce a supplementary algorithm in order to work out the low-level AMVs in the clear area with FY-2E long wave, window (10.3~11.5, 11.6~12.8 ?m) channel imagery. It has been shown that the weak signals indicating water vapor in "cloud-free region" can be extracted from FY-2E long wave infrared imagery and may be used as tracers for atmospheric motion vectors. The algorithm, named as Second Order difference method, has been raised in order to weaken the surface temperature interference to the weak signals of water vapor in "cloud-free region" by means of split window and temporal difference calculations. The results from theory analysis and cases study show that this method can make up for the wind data in regions lack of cloud but rich of water vapor and comparison between the wind vectors from this method and the NCEP reanalysis data shows a good consistency.

  19. Lake-river-atmosphere Interactions as Simulated by the Canadian Regional Climate Model (CRCM5) over North-east Canada

    NASA Astrophysics Data System (ADS)

    Huziy, O.; Sushama, L.; Laprise, R.

    2014-12-01

    Lakes are important components of the climate system and can affect regional climate by modulating surface albedo, surface energy and moisture budgets, especially for the lake rich regions such as Canada. From the regional hydrology perspective, interactions between lakes and rivers are important as streamflow patterns can be significantly modified by lake storage, while lake levels can be modified by streamflows. In this study, using a suite of experiments performed with the fifth generation of the Canadian Regional Climate Model (CRCM5), we try to assess the interactions between lakes and rivers and their impact on the atmosphere, over north-east Canada; in these simulations lakes are represented by the Hostetler model, while rivers are modelled using the modified WATROUTE scheme, including interflow. Comparison of CRCM5 simulations with and without lakes suggests big differences in winter/summer precipitation and winter temperature. CRCM5 simulations performed with and without lake-river interactions suggest improved representation of streamflows when lake storage is taken into account. Introduction of interflow shows some streamflow increases during summer and fall seasons, for majority of the rivers, and some impacts on the land atmosphere interactions via modified soil moisture.

  20. The Structure of the Upper Atmosphere of Venus - New Measurements and Models of the Northern Polar Region

    NASA Astrophysics Data System (ADS)

    Svedhem, H.; Mueller-Wodarg, I. C.; Rosenblatt, P.

    2011-12-01

    Until recently the only information on the structure of the polar upper atmosphere of Venus available has been based on the reference atmosphere models such as the VTS3 or VIRA models. These models extrapolate the values from low latitudes to high latitudes by using equivalent solar zenith angles. New measurements by Venus Express show that such extrapolations not always give correct results and that there is a general overestimate of the density at high latitudes. These new results have been reached by using two different but related techniques, both using an atmospheric drag effect on the spacecraft. By reducing the pericentre altitude the total mass density in the altitude range 150-200km can be measured in situ by monitoring the orbital decay caused by the drag on the spacecraft by the atmosphere via direct tracking of the Doppler signal on the telecommunication link. Such measurements have been performed with Venus Express several times during the last years as part of the Venus Express Atmospheric Drag Experiment (VExADE). The results indicate a large variability within only a few days and have led to questions if these variations are real or within the uncertainty of the measurements. A completely different and independent measurement is given by monitoring the torque asserted by the atmosphere on the spacecraft. This is done by monitoring the momentum accumulated in the reaction wheels during the pericentre pass and at the same time considering all other perturbing forces. This requires the spacecraft to fly in an asymmetric attitude with respect to the centre of gravity, centre of drag and the velocity vector. This technique has proven very sensitive, in particular if the geometric asymmetry is large, and offers an additional method of measuring atmospheric densities in-situ that previously had not been explored with the Venus Express spacecraft. Similar measurements have been done in the past by Magellan at Venus and by Cassini at Titan. Between 2009 and 2011 several campaigns, with altitudes going as low as 165 km, were held. The highest density measured was 7.7 10-12kg/m3 which is significantly less than earlier models predict. The results largely confirm the density measurements by the VExADE drag measurements and add to the confidence in the results from these measurements. By using these drag and torque results and assuming a hydrostatic diffusive equilibrium atmosphere a new model has been constructed. The model is fitted to the Venus Express remote sensing measurements in the upper mesosphere (VeRa radio occultation data) and lower thermosphere (SpicaV/SOIR data) to give a continuous transition across the different regions.

  1. Variability of solar/stellar activity and magnetic field and its influence on planetary atmosphere evolution

    NASA Astrophysics Data System (ADS)

    Lammer, Helmut; Güdel, Manuel; Kulikov, Yuri; Ribas, Ignasi; Zaqarashvili, Teimuraz V.; Khodachenko, Maxim L.; Kislyakova, Kristina G.; Gröller, Hannes; Odert, Petra; Leitzinger, Martin; Fichtinger, Bibiana; Krauss, Sandro; Hausleitner, Walter; Holmström, Mats; Sanz-Forcada, Jorge; Lichtenegger, Herbert I. M.; Hanslmeier, Arnold; Shematovich, Valery I.; Bisikalo, Dmitry; Rauer, Heike; Fridlund, Malcolm

    2012-02-01

    It is shown that the evolution of planetary atmospheres can only be understood if one recognizes the fact that the radiation and particle environment of the Sun or a planet's host star were not always on the same level as at present. New insights and the latest observations and research regarding the evolution of the solar radiation, plasma environment and solar/stellar magnetic field derived from the observations of solar proxies with different ages will be given. We show that the extreme radiation and plasma environments of the young Sun/stars have important implications for the evolution of planetary atmospheres and may be responsible for the fact that planets with low gravity like early Mars most likely never build up a dense atmosphere during the first few 100 Myr after their origin. Finally we present an innovative new idea on how hydrogen clouds and energetic neutral atom (ENA) observations around transiting Earth-like exoplanets by space observatories such as the WSO-UV, can be used for validating the addressed atmospheric evolution studies. Such observations would enhance our understanding on the impact on the activity of the young Sun on the early atmospheres of Venus, Earth, Mars and other Solar System bodies as well as exoplanets.

  2. Innovative optical spectrometers for ice core sciences and atmospheric monitoring at polar regions

    NASA Astrophysics Data System (ADS)

    Grilli, Roberto; Alemany, Olivier; Chappellaz, Jérôme; Desbois, Thibault; Faïn, Xavier; Kassi, Samir; Kerstel, Erik; Legrand, Michel; Marrocco, Nicola; Méjean, Guillaume; Preunkert, Suzanne; Romanini, Daniele; Triest, Jack; Ventrillard, Irene

    2015-04-01

    In this talk recent developments accomplished from a collaboration between the Laboratoire Interdisciplinaire de Physique (LIPhy) and the Laboratoire de Glaciologie et Géophysique de l'Environnement (LGGE) both in Grenoble (France), are discussed, covering atmospheric chemistry of high reactive species in polar regions and employing optical spectrometers for both in situ and laboratory measurements of glacial archives. In the framework of an ANR project, a transportable spectrometer based on the injection of a broadband frequency comb laser into a high-finesse optical cavity for the detection of IO, BrO, NO2 and H2CO has been realized.[1] The robust spectrometer provides shot-noise limited measurements for as long as 10 minutes, reaching detection limits of 0.04, 2, 10 and 200 ppt (2?) for the four species, respectively. During the austral summer of 2011/12 the instrument has been used for monitoring, for the first time, NO2, IO and BrO at Dumont d'Urville Station at East of Antarctica. The measurements highlighted a different chemistry between East and West coast, with the halogen chemistry being promoted to the West and the OH and NOx chemistry on the East.[2] In the framework of a SUBGLACIOR project, an innovative drilling probe has been realized. The instrument is capable of retrieving in situ real-time vertical profiles of CH4 and ?D of H2O trapped inside the ice sheet down to more than 3 km of depth within a single Antarctic season. The drilling probe containing an embedded OFCEAS (optical-feedback cavity-enhanced absorption spectroscopy) spectrometer will be extremely useful for (i) identify potential sites for investigating the oldest ice (aiming 1.5 Myrs BP records for resolving a major climate reorganization called the Mid-Pleistocene transition occurred around 1 Myrs ago) and (ii) providing direct access to past temperatures and climate cycles thanks to the vertical distribution of two key climatic signatures.[3] The spectrometer provides detection limit of 0.2 ppbv for CH4 and a precision of 0.2o on the ?D of H2O within ~1 min of integration time. The spectrometer and the home-made gas sampling has been tested during an oceanographic campaign last summer in the Mediterranean Sea, measuring the vertical distribution of CH4 dissolved in seawater. The project is now moving forward its final goal which consists of employing the probe for a first test season at Concordia station during the Austral summer of 2016/17, and then for the 'oldest ice challenge' drilling season scheduled in the Austral summer of 2017/18. Finally, preliminary results on the isotope ratio measurements of CO18O,13CO2 and 13CO18O will be presented. A novel spectrometer, based on OFCAES technique employing a Quantum Cascade Laser around 4.4 ?m wavelength, offers a precision below 0.05 o for the three isotopic anomalies, for 200 ppmv of CO2 samples. The optical device will be employed for laboratory experiments coupling it with a continuous ice-crushing extraction system for analyzing trapped bubbles of gas in Antarctica ice cores. [1] R. Grilli, G. Méjean, S. Kassi, I. Ventrillard, C. Abd-Alrahman, and D. Romanini, 'Frequency Comb Based Spectrometer for in Situ and Real Time Measurements of IO, BrO, NO2, and H2CO at pptv and ppqv Levels.,' Environ. Sci. Technol., vol. 46, no. 19, pp. 10704-10, Oct. 2012. [2] R. Grilli, M. Legrand, A. Kukui, G. Méjean, S. Preunkert, and D. Romanini, 'First investigations of IO, BrO, and NO2 summer atmospheric levels at a coastal East Antarctic site using mode-locked cavity enhanced absorption spectroscopy,' Geophys. Res. Lett., vol. 40, pp. 1-6, Feb. 2013. [3] R. Grilli, N. Marrocco, T. Desbois, C. Guillerm, J. Triest, E. Kerstel, and D. Romanini, 'Invited Article: SUBGLACIOR: An optical analyzer embedded in an Antarctic ice probe for exploring the past climate,' Rev. Sci. Instrum., vol. 85, no. 111301, pp. 1-7, 2014.

  3. Interglacial Surface Ocean Temperatures Reveal Strong Ocean-Atmosphere Linkages Between the Subtropical and Subpolar Regions

    Microsoft Academic Search

    E. Kandiano; H. A. Bauch; K. Fahl; J. Helmke; U. Roehl

    2008-01-01

    Investigating ocean-atmospheric processes of past interglaciations may provide a better understanding of the climatic development of the present warm period. Here we present a detailed reconstruction of the meridional sea surface temperature (SST) across MIS 11 using three sites: ODP 958 (off NW Africa), ODP 975 (western Mediterranean Sea) and M23414 (subpolar NE Atlantic). Sea surface temperatures (SST) were derived

  4. Satellite estimates of shortwave surface radiation and atmospheric meteorology for the BOREAS experiment region

    NASA Technical Reports Server (NTRS)

    Moats, C. D.; Whitlock, C. H.; Lecroy, S. R.; Dipasquale, R. C.

    1994-01-01

    This report provides background data for the Boreal Ecosystem Atmosphere Study (BOREAS) sites, including daily, seasonal, interannual, and spatial variability of shortwave (SW) radiation at the Earth's surface. This background data, from the Version 1.1 SW data set, was provided by the Surface Radiation Budget (SRB) Climatology Project established by the World Climate Research Program (WCRP).

  5. Influence of marine denitrification on atmospheric N2O variability during the Holocene

    NASA Astrophysics Data System (ADS)

    Agnihotri, Rajesh; Altabet, Mark A.; Herbert, T. D.

    2006-07-01

    Oceanic denitrification centers are thought to be important marine sources for atmospheric N2O. To consider Holocene variability in this source, we reconstruct the Holocene paleo-denitrification history of the Peru margin, a major marine denitrification center, using high-resolution sedimentary ?15N data. This record along with a contemporaneous one from the western Arabian Sea (Altabet et al., 2002) shows similarities with the recently available high-resolution atmospheric N2O record (Flückiger et al., 2002). While the role of terrestrial processes in the observed N2O changes remains uncertain, these results suggest that variability in marine denitrification in major upwelling centers such as the Peru margin and the Arabian Sea contributed significantly to atmospheric N2O evolution during the Holocene.

  6. Influences of atmospheric conditions and air mass on the ratio of ultraviolet to total solar radiation

    SciTech Connect

    Riordan, C.J.; Hulstrom, R.L.; Myers, D.R.

    1990-08-01

    The technology to detoxify hazardous wastes using ultraviolet (UV) solar radiation is being investigated by the DOE/SERI Solar Thermal Technology Program. One of the elements of the technology evaluation is the assessment and characterization of UV solar radiation resources available for detoxification processes. This report describes the major atmospheric variables that determine the amount of UV solar radiation at the earth's surface, and how the ratio of UV-to-total solar radiation varies with atmospheric conditions. These ratios are calculated from broadband and spectral solar radiation measurements acquired at SERI, and obtained from the literature on modeled and measured UV solar radiation. The following sections discuss the atmospheric effects on UV solar radiation and provide UV-to-total solar radiation ratios from published studies, as well as measured values from SERI's data. A summary and conclusions are also given.

  7. Influence of sub-grid scale parameterizations on atmospheric variability over a heterogeneous agricultural area

    NASA Astrophysics Data System (ADS)

    Timmermans, Wim; Andreu, Ana; Porté-Agel, Fernando; Albertson, John

    2015-04-01

    Virtually all remote sensing based Soil-Vegetation-Atmosphere Transfer (SVAT) Schemes assume homogeneous, or decoupled atmospheric variables over their modeling domain. This assumption can lead to erroneous flux estimation since landscapes are inherently heterogeneous with variability in land surface state variables inducing spatial variability in the near surface air properties, which in turn affect the fluxes. A Large Eddy Simulation (LES) model is coupled to a remote sensing based SVAT that accounts for soil and vegetation (dual source) contributions to mass and energy exchanges in order to study the feedback effects between spatially variable land cover and spatial variability in fluxes, through the induction of spatial variability in the lower atmosphere. Previous studies demonstrated that an increase in the correlation between surface and lower boundary layer states with increasing surface state contrast modulated relative increases in the spatial variance in the sensible heat flux. A multi-scale analysis of the land - atmosphere feedback, using a simple wavelet decomposition technique, showed the most significant correlation at scales from 500 to 1000 m. These feedback effects act to limit the spatial variability in the flux, implying that ignoring atmospheric feedback from land surface turbulent exchange rates will cause the largest errors at the extremes. To improve the modelling of spatially distributed fluxes a better understanding of how the surface heterogeneities are transported into the lower atmospheric boundary layer is needed. Near the surface the momentum and scalar (temperature and moisture) transport is dominated by the smallest size eddies. Therefore, typically the performance of Large Eddy Simulation models near the surface depends largely on the performance of the so-called Sub-Grid-Scale (SGS) parameterizations of momentum and scalar fluxes. The effect of recently developed scale-invariant and scale-dependent dynamic SGS models for viscosity and diffusivity is discussed using airborne and ground-based observations from a campaign (REFLEX-2012) over a heterogeneous agricultural area in the southern part of Spain.

  8. Detection of deep atmospheric disintegration of a large meteoroid over the northern Adriatic region by a seismic network on July 25, 2007

    Microsoft Academic Search

    J. Atanackov; J. Kac; G. Kladnik

    2009-01-01

    An atmospheric disintegration of a large meteoroid over the northern Adriatic region was observed by numerous witnesses and detected by seismographs of the Environmental Agency of Slovenia on July 25, 2007. Analysis of seismic records produced an approximate atmospheric trajectory of the body, its fragmentation sequence and an estimate of the energy released during individual fragmentation events. Seismographs show evidence

  9. Modification of SeaDAS SWIR atmospheric correction scheme for accurate retrieval of NIR remote sensing reflectance in the river delta regions of the world

    Microsoft Academic Search

    James E. Davies; Colleen B. Mouw; Chris C. Moeller

    2010-01-01

    Coastal waters in the vicinity of the river delta regions of the world are characterized by significant concentrations of suspended sediments. To estimate the water sediment load from satellite observations, an important step is to accurately remove the optical effects of the intervening atmosphere. The NASA SeaDAS code has been shown to accurately correct MODIS satellite data for atmospheric effects

  10. Understanding of the atmospheric methane evolution and change over the last 30 years with focus on the Arctic region

    NASA Astrophysics Data System (ADS)

    Platt, Stephen; Myhre, Cathrine Lund; Dalsoren, Stig; Hermansen, Ove; Myhre, Gunnar

    2015-04-01

    The methane (CH4) concentration is increasing in the atmosphere, both globally and in the Arctic region since ~2005. The explanation to this is currently not well understood. There are huge reservoirs of CH4 in the Arctic; both methane hydrates in seabed sediments, and organic material in land- and marine-based permafrost which can be partly converted to CH4 after permafrost thaw. Both are vulnerable to destabilization in a warming climate. The Arctic Ocean surface waters may also represent a potentially important source of CH4, which may be sensitive to changes in sea-ice cover. Previous studies show strong atmospheric chemistry feedback to climate warming from Arctic methane emissions. Final results from the GAME project (Causes and effects of Global and Arctic changes in the MEthane budget), and first results from the MOCA project (Methane Emissions from the Arctic OCean to the Atmosphere: Present and Future Climate Effects: http://moca.nilu.no) will be presented. One goal of these studies is to improve the understanding on how emissions in different regions, transport and chemical processes contribute to observed changes in atmospheric methane distribution the last 40 years, with particular focus on the Arctic, including CH4 emissions from the ocean like the East Siberian Arctic Shelf. The work is an integrated study combining new measurements at Zeppelin Observatory, Svalbard, analysis of existing and ongoing methane observations and other relevant species, and Chemical Transport Modelling (CTM). The Oslo CTM3 model is used to calculate distribution and changes over the last 40 years. The study include evaluation of different methane sources and source regions, and chemical processes affecting OH distribution and changes, including changes in anthropogenic and natural emissions from different sources. The Norwegian Research council through the project GAME (Causes and effects of Global and Arctic changes in the MEthane budget), and MOCA (Methane Emissions from the Arctic OCean to the Atmosphere:Present and Future Climate Effects: http://moca.nilu.no) is highly acknowledged for the support and funding of this activity.

  11. A direct human influence on atmospheric CO2 seasonality from increased cropland productivity

    NASA Astrophysics Data System (ADS)

    Gray, J. M.; Frolking, S. E.; Kort, E. A.; Ray, D. K.; Kucharik, C. J.; Ramankutty, N.; Friedl, M. A.

    2014-12-01

    Ground- and aircraft-based measurements show that the seasonal amplitude of Northern Hemisphere atmospheric carbon dioxide (CO2) concentrations has increased by as much as 50% over the last 50 years. This increase has been linked to changes in Temperate, Boreal and Arctic ecosystem properties and processes such as enhanced photosynthesis, increased heterotrophic respiration, and expansion of woody vegetation. However, the precise causal mechanisms behind observed changes in atmospheric CO2 seasonality remain unclear. Here we show that increases in agricultural productivity, which have been largely overlooked in previous investigations, explain as much as 25% of observed changes in atmospheric CO2 seasonality, and perhaps more. Specifically, Northern Hemisphere extratropical maize, wheat, rice, and soybean production grew by 240% between 1961-2008, thereby increasing the amount of net carbon uptake by croplands during the Northern Hemisphere growing season by 0.33 Pg. Maize alone accounts for two-thirds of this change, owing mostly to agricultural intensification within concentrated production zones in the Midwestern United States and Northern China. Since a substantial portion of seasonality enhancement results from a process that is roughly neutral in terms of its impact on the terrestrial carbon sink, our results show that care must be taken when making inferences regarding the linkages between CO2 seasonality and terrestrial carbon sink dynamics. More generally, these results demonstrate how intensive management of agricultural ecosystems over the last five decades have imparted a substantial and direct fingerprint of anthropogenic activities on seasonal patterns of Northern Hemisphere atmospheric CO2.

  12. The nitrogen phosphorus relationship in mountain lakes: Influence of atmospheric input, watershed, and pH

    Microsoft Academic Search

    JIRI KOPACEK; Lidmila Prochdzkovci; EVZEN STUCHLÍK; PAVEL BLAZKA

    1995-01-01

    The impact of high N input on the trophic status of small mountain lakes as modified by the type of watershed and stage of acidification in two central European mountain ranges (the High Tatra Mts. and the Sumava Mts.) is reported. Atmospheric N deposition enhanced nitrate concentrations of lake water, but the type of watershed determined both the share of

  13. Changes in atmospheric CO2 - Influence of the marine biota at high latitude

    Microsoft Academic Search

    Fanny Knox; M. B. McElroy

    1984-01-01

    Approximately half of the nitrogen and phosphorus entering deep waters of the contemporary ocean are transported from the surface in inorganic form as preformed nutrients. A simple model for ocean chemistry is presented and shown to account for the present level of atmospheric CO2. Fluctuations in preformed nutrients, modulated by changes in insolation and circulation at high latitudes, can result

  14. Influence of Room-Temperature Atmospheric Reaction Products on the Ductility of Sodium Chloride Single Crystals

    Microsoft Academic Search

    Dumas A. Otterson

    1963-01-01

    Bend tests were made using sodium chloride single crystals which had previously been exposed to one of several atmospheres at room temperature. Crystals exposed to moist carbon dioxide showed the most consistent brittle behavior while those aged in moist air containing hydrogen chloride showed more ductile behavior. Evidence is given which indicates that hydroxide ion is needed for carbon dioxide

  15. Variable influence of the atmospheric flux on the trace metal chemistry of oceanic suspended matter

    Microsoft Academic Search

    P. Buat-Menard; R. Chesselet

    1979-01-01

    The particulate concentrations of 17 trace metals, Al, Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Se, Ag, Sb, Au, Hg, Pb and Th have been measured in the marine atmosphere (58 samples) and in the deep waters (35 samples) of the Tropical North Atlantic. For oceanic suspended matter, our results are similar to those in samples from the

  16. The influence of atmospheric thermal tides on diurnal variations in chemical constituents in the mesosphere

    Microsoft Academic Search

    Gudmundur Gisli Bjarnason

    1987-01-01

    Numerous observations have shown large diurnal changes of chemical species such as ozone and OH in the upper earth atmosphere. Many of these changes cannot be explained by photochemistry alone, so other physical processes must play an important role. To investigate the possible interaction of dynamics and photochemistry, a one-dimensional photochemical model was developed which includes a time varying vertical

  17. Differential Influence of Components Resulting from Atmospheric-Pressure Plasma on Integrin Expression of Human HaCaT Keratinocytes

    PubMed Central

    Haertel, Beate; Straßenburg, Susanne; Wende, Kristian; von Woedtke, Thomas

    2013-01-01

    Adequate chronic wound healing is a major problem in medicine. A new solution might be non-thermal atmospheric-pressure plasma effectively inactivating microorganisms and influencing cells in wound healing. Plasma components as, for example, radicals can affect cells differently. HaCaT keratinocytes were treated with Dielectric Barrier Discharge plasma (DBD/air, DBD/argon), ozone or hydrogen peroxide to find the components responsible for changes in integrin expression, intracellular ROS formation or apoptosis induction. Dependent on plasma treatment time reduction of recovered cells was observed with no increase of apoptotic cells, but breakdown of mitochondrial membrane potential. DBD/air plasma increased integrins and intracellular ROS. DBD/argon caused minor changes. About 100?ppm ozone did not influence integrins. Hydrogen peroxide caused similar effects compared to DBD/air plasma. In conclusion, effects depended on working gas and exposure time to plasma. Short treatment cycles did neither change integrins nor induce apoptosis or ROS. Longer treatments changed integrins as important for influencing wound healing. Plasma effects on integrins are rather attributed to induction of other ROS than to generation of ozone. Changes of integrins by plasma may provide new solutions of improving wound healing, however, conditions are needed which allow initiating the relevant influence on integrins without being cytotoxic to cells. PMID:23936843

  18. Influence of stratification in near-surface water layer on intensity of gas exchange between atmosphere and water

    NASA Astrophysics Data System (ADS)

    Brekhovskikh, V. F.; Bratkov, V. I.

    1986-07-01

    Little is known concerning the influence of the temperature field in the near-water layer on gas exchange between the atmosphere and water. During periods of calm the transfer of oxygen from the air to water is sometimes impeded and large numbers of fish may die. A laboratory experiment was carried out in glass thermostated containers, in each of which the temperature was maintained with great accuracy. One was heated to 39 to 40 C; another was cooled to 12 to 13 C; a third was kept at ambient temperature. In each case the aeration coefficient and rate of mass transfer were computed. Air and water temperatures were varied to determine temperature gradients in the near-water and near-surface layers. A copper constantan thermocouple was used in measuring temperatures above and below the interface. The influence of petroleum films on the rate of mass transfer was also determined. The rate of evaporation at different temperatures was ascertained. The greatest influence was observed in experiments with cooled air. It was found that temperature stratification in the near-surface water layer exerts a considerable influence on water-air gas exchange. In certain cases a petroleum film increases the temperature gradient and causes an even greater decrease in mass transfer rate.

  19. Influence of Atmospheric Variations on Photovoltaic Performance and Modeling Their Effects for Days with Clear Skies: Preprint

    SciTech Connect

    Marion, B.

    2012-06-01

    Although variation in photovoltaic (PV) performance is predominantly influenced by clouds, performance variations also exist for days with clear skies with different amounts of atmospheric constituents that absorb and reflect different amounts of radiation as it passes through the earth's atmosphere. The extent of the attenuation is determined by the mass of air and the amounts of water vapor, aerosols, and ozone that constitute the atmosphere for a particular day and location. Because these constituents selectively absorb radiation of particular wavelengths, their impact on PV performance is sensitive to the spectral response of the PV device. The impact may be assessed by calculating the spectral mismatch correction. This approach was validated using PV module performance data at the National Renewable Energy Laboratory (NREL) for summer, fall, and winter days with clear skies. The standard deviation of daily efficiencies for single-crystal Si, a-Si/a-Si/a-Si:Ge, CdTe, and CIGS PV modules were reduced to 0.4% to 1.0% (relative) by correcting for spectral mismatch, temperature, and angle-of-incidence effects.

  20. Using Dynamically Coupled Turbine/Wind Simulations to Investigate the Influence of Atmospheric Turbulence in Turbine Wake Recovery

    NASA Astrophysics Data System (ADS)

    Linn, R.; Koo, E.; Kelley, N. D.; Jonkman, B.; Lundquist, J. K.; Canfield, J.

    2010-12-01

    In order to increase our efficiency of energy capture in wind farms, optimize turbine arrangements, and adapt wind-turbine technology to optimal performance in common atmospheric conditions such as low level jets (LLJ), it is critical to understand the dynamic interactions between turbulence and multiple wind turbines. Ambient atmospheric turbulence interacts with spinning turbines producing the critical mechanism for the recovery of the wind field behind a wind turbine. This turbine-influenced turbulent wind field creates the environment surrounding downstream turbines in a wind farm, thus controlling the amount of wind energy available for harvesting as well as the nature of the wear and tear that downwind turbines endure. The strength of the turbulent structures and their length-scales evolve downstream. Thus, the conditions to which downstream turbines are exposed, their productivity, and potentially their lifespan is a function of their position within the turbulent wake of upstream turbines. A numerical technique, WindBlade, has been developed for characterizing the interaction of spinning wind turbines and unsteady/heterogeneous atmospheric boundary layers at length scales ranging from blade-chord-scale (meters) to turbine-array-scale (multiple kilometers). This implementation of this technique combines an R&D100 winning numerical tool, HIGRAD/FIRETEC, a fully-compressible atmospheric hydrodynamics model with novel techniques to capture forces exchanged between the atmosphere and turbine as it rotates. The blade-induced forces on the wind field over the along the span of spinning turbine blades interacts with any oncoming atmospheric turbulence or shear, thus producing turbine wakes which are functions of turbine blade geometry and pitch, rotation speed, topographic and vegetation influences, and of course ambient wind speed, direction, shear, and turbulence. TurbSim, which creates vertical planes of three-dimensional turbulent wind fields based on empirical data from various sites, is used to initialize the turbulence in the domain initially and then the produce dynamically evolving turbulent wind inflow conditions. WindBlade simulations have been performed to study the integrated impact of blade chord-scale force exchange between atmosphere and turbines on downstream wakes in conditions ranging from idealized laminar winds to empirically-based TurbSim turbulent LLJ conditions. This series of simulations reveal that the dynamic interaction between turbines and ambient turbulence has drastic effects on the wake structure and recovery. Functional relationships between downstream-turbine conditions and separation distance are strongly influenced by the ambient turbulence. These simulations explicitly illustrate evolution of length scales in the turbine wake and suggest optimal separation distance for turbines in a wind farm is likely a balance between available wind energy for harvesting and optimizing the nature of the turbulence that the turbine must continuously endure.

  1. REGIONAL ATMOSPHERIC CIRCULATION AND SURFACE TEMPERATURES PREDICTING COTTON YIELDS IN THE SOUTHEASTERN USA

    Microsoft Academic Search

    Guillermo A. Baigorria; James W. Hansen; Neil Ward; James W. Jones; James J. O'Brien

    Research has shown strong relationship s between ENSO phase and climate in the southeastern USA during the boreal winter. Crop yields in this region are significantly affected by ENSO phase due to predictable patterns of climate during this time of the year. However, both climate during the boreal summer months and cotton yields in this region show little or no

  2. Influence of climate change on atmospheric transport of persistent organic pollutants to the Arctic

    NASA Astrophysics Data System (ADS)

    Hansen, Kaj M.; Chrsitensen, Jesper H.; Brandt, Jørgen

    2014-05-01

    We have applied the Danish Eulerian Hemispheric Model (DEHM) to study the impact of climate change on atmospheric transport of Persistent Organic Pollutants (POPs) to the Arctic as well as investigating the major source areas for the transport to the Arctic. The study represents a sensitivity analysis in order to investigate the response of the model system due to climate change. DEHM is a 3-D atmospheric chemistry-transport model modelling the atmospheric transport of four chemical groups: a group with SOx-NOx-VOC-ozone chemistry, a group with primary particulates group, a mercury chemistry group, and finally a group with Persistent Organic Pollutants (two HCH isomers and 11 PCB congeners). The model domain covers the Northern Hemisphere and thus includes all important source areas for the Arctic. The spatial horizontal resolution of the model system in this work is 150km x 150km and the model includes 20 vertical levels up to approximately 15km above the surface. The model system was run with meteorology obtain from ECHAM5/MPI-OM (SRES A1B scenario) for two decades: 1990-1999 and 2090-2099. In this climate scenario the global mean temperature is predicted to increase by 3ºC by the end of 2100 relative to the period 1971-2000. The same emissions where applied for the two simulations. It is thus possible to investigate the response of DEHM to a changed climate on e.g. the atmospheric transport of POPs to the Arctic. Higher temperature leads to a shift of POPs from the surface media to air. Higher temperatures also lead to larger degradation in air as well as in the surface media. This results in lower modelled masses for the 2090s than for the 1990s within the entire model domain for all modelled species. The higher atmospheric concentrations also result in larger atmospheric transport to the Arctic. For the least chlorinated PCB congeners the increased transport is counteracted by the increased degradation and the result is thus approximately 10% less mass within the Arctic in the 2090s compared to the 1990s. The mass of the more chlorinated PCB congeners with a larger affinity to aerosols (and thus less degradation) is up to 20% higher in the 2090s than in the 1990s. The mass of the HCH isomers within the Arctic is up to 30% higher in the 2090s than in the 1990s due to a larger ice free ocean and increased wet deposition.

  3. Inferences on the thermodynamic characteristics of a star from the observed distinctive radial sequences of the distinctive atmospheric regions comprising that stellar atmosphere

    SciTech Connect

    Not Available

    1983-01-01

    The implications of observational findings on atmospheric and subatmospheric taxonomy, diagnostics, and modeling are explored. The correlations between distinctive radial sequences in stellar atmospheres and the thermodynamic properties of the stars in which they appear are discussed.

  4. Near-surface climate of the Antarctic Peninsula as simulated by a high-resolution regional atmospheric climate model

    NASA Astrophysics Data System (ADS)

    van Wessem, M.; Reijmer, C.; van den Broeke, M. R.

    2014-12-01

    The latest polar version of the regional atmospheric climate model RACMO2 (RACMO2.3) has been applied to the Antarctic Peninsula. Recently, the model physics have been updated, which resulted in a significant improvement in its performance, at 27 km resolution, over East and West Antarctica, in terms of surface energy fluxes and surface mass budget. Here we present results from a climatological run at 5.5 km over the AP for the period 1979-2013, in which RACMO2.3 is forced by ERA-Interim atmospheric and ocean surface fields and includes an AP surface topography based on state of the art digital elevation models. RACMO2.3 resolves the extremely large gradients over the Antarctic Peninsula mountain spine, in terms of surface and 2 meter temperature, which are caused by the persistent atmospheric westerly winds. We evaluate the model results by comparing them to temperature series from manned and automatic weather stations, vertical profiles from balloon soundings and surface energy balance measurements from three automatic weather stations. Results show that RACMO2.3 performs well in terms of surface and 2 m temperatures, 10 m wind speed/direction, but we also identify some significant biases in the downwelling fluxes of shortwave- and longwave radiation, related to clouds. These biases largely compensate each other, however, so that melt energy fluxes are resolved with reasonable accuracy.

  5. Structures and characteristics of the windy atmospheric boundary layer in the South China Sea region during cold surges

    NASA Astrophysics Data System (ADS)

    Cheng, Xue-Ling; Huang, Jian; Wu, Lin; Zeng, Qing-Cun

    2015-06-01

    An observational analysis of the structures and characteristics of a windy atmospheric boundary layer during a cold air outbreak in the South China Sea region is reported in this paper. It is found that the main structures and characteristics are the same as during strong wind episodes with cold air outbreaks on land. The high frequency turbulent fluctuations (period <1 min) are nearly random and isotropic with weak coherency, but the gusty wind disturbances (1 minatmospheric boundary layer at sea, compared with that over land, there are some pronounced differences: (1) the average horizontal speed is almost independent of height, and the vertical velocity is positive in the lower marine atmospheric boundary layer; (2) the vertical flux of horizontal momentum is nearly independent of height in the low layer indicating the existence of a constant flux layer, unlike during strong wind over the land surface; (3) the kinetic energy and friction velocity of turbulent fluctuations are larger than those of gusty disturbances; (4) due to the independence of horizontal speed to height, the horizontal speed itself (not its vertical gradient used over the land surface) can be used as the key parameter to parameterize the turbulent and gusty characteristics with high accuracy.

  6. The influence of the North Atlantic Oscillation on the regional temperature variability in Sweden: spatial and temporal variations

    Microsoft Academic Search

    Deliang Chen; Cecilia Hellström

    1999-01-01

    A statistical analysis of the seasonal and interannual variations in the regional temperature anomalies of Sweden during 1861 1994 is performed. The study uses homogenized monthly temperatures averaged over 6 regions to minimize the non climatic and local-scale climatic effects. It is found that the temperature variability shows a clear regional and seasonal dependency. The topography, the influence of the

  7. Background levels of atmospheric mercury in Kagoshima City, and influence of mercury emission from Sakurajima Volcano, Southern Kyushu, Japan

    PubMed

    Tomiyasu; Nagano; Sakamoto; Yonehara

    2000-10-01

    Vapor phase mercury concentration was determined daily for 1 year (Jan. 1996-Jan. 1997) in order to present the levels of atmospheric mercury in Kagoshima City and to estimate the influence of mercury emission from Sakurajima Volcano, southern Kyushu, Japan. The atmospheric mercury was collected on a porous gold collector at Kagoshima University and was determined by cold vapor atomic absorption spectrometry; Kagoshima University of Kagoshima City is located approximately 11 km west of Sakurajima Volcano. The mercury concentration obtained was in the range 1.2-52.5 ng m(-3) (mean 10.8 ng m(-3), n = 169). The atmospheric concentration varied from season to season; the concentration was high in summer and lower in winter. A linear relation was obtained by plotting ln[Hg/ng m(-3)] vs. 1/T for the north, south and west winds with correlation coefficients of -0.76, -0.79 and -0.83, respectively, but no such dependency was found for the east wind (r = -0.035). When the wind is blowing from the east, Kagoshima City is on the leeward side of the volcano. The impact of the fumarolic activity of the volcano on ambient air in the city was evident in the disappearance of temperature dependency with the appearance of the east wind. Atmospheric mercury concentration except for the east wind was considered to be background levels of Kagoshima City. As background levels, 8.1 +/- 5.3 ng m(-3), 14.8 +/- 7.9 ng m(-3), 13.9 +/- 11.7 ng m(-3) and 4.4 +/- 1.6 ng m(-3) (mean +/- S.D.) were obtained for spring, summer, autumn and winter, respectively. PMID:11032152

  8. Plasma Flows in the Chromosphere-Corona Transition Region of the Solar Atmosphere

    NASA Astrophysics Data System (ADS)

    Ptitsyna, Olga; Somov, Boris

    For various plasma flux velocities specified on the lower boundary of the chromosphere-corona transition region, we find temperature dependencies of plasma concentration, velocity and pressure along magnetic tube with one end immersed in the chromosphere and the other end located in the corona. We also obtain stationary temperature distributions along magnetic tube. At each point of the distribution, there is a balance between the heating by the classical heat flux, the energy losses through the radiation of optically thin plasma and the energy transport associated with plasma flow. We then determine: the range of velocities at the lower boundary of the chromosphere-corona transition region for which generation of shock waves in the transition region is possible; the range of velocities at the lower boundary of the chromosphere-corona transition region, for which transition region can be cousidered in the classical collisional approximation, and the range of velocities at the lower boundary of the chromosphere-corona transition region, for which the heating regime is close to p = const and computed radiation values are consistent with the results of satellite observations of extreme ultraviolet (EUV) radiation from the transition region.

  9. Pasquill`s influence: on the evaporation from various liquids into the atmosphere

    Microsoft Academic Search

    1995-01-01

    Pasquill`s development of an evaporation model as well as his experimental work on the subject are important in view of the recent emphasis on toxic chemical releases to the environment. Pasquill`s contributions to the field of atmospheric diffusion are enormous and well-known. The Pasquill stability classification enables us to apply the Gaussian diffusion model in our daily life. The Gaussian

  10. Influence of packaging atmospheres on the durability of high-temperature SAW sensors

    Microsoft Academic Search

    Jochen Bardong; Gudrun Bruckner; Martin Kraft; R. Fachberger

    2009-01-01

    Surface acoustic wave (SAW) devices are a technology of choice for passive, radio-interrogable sensor applications operating under extreme conditions. Suitably designed SAW devices can withstand e.g. temperatures exceeding 400°C. At high temperatures (HT), thermal energies reach values corresponding to the activation energies of reactions between gas components and the crystal's substrate elements and\\/or the metallisation elements, respectively. Thus, the atmosphere

  11. Influence of strong electric field on MDA and SOD of rice under atmosphere pressure

    NASA Astrophysics Data System (ADS)

    Xiong, Jianping; Hu, Shengyong; Li, Jikai; He, Songqing; Feng, Lixin

    2013-03-01

    The content of MDA is measured by TBA method in the experiment. The results show that the MDA content of rice seedlings after being radiated in a strong electric field under atmosphere pressure decreases compared to that of those not being radiated while the SOD activity decreases. It indicates that radiated seeds' resistance against oxidative stress can be greatly enhanced. The mechanism and relation between them are analyzed in this paper.

  12. Daily simulation using a three-dimensional atmosphere-ocean regional coupled model, CReSS-NHOES over the CINDY/DYNAMO observation region

    NASA Astrophysics Data System (ADS)

    Shinoda, T.; Yoshioka, M. K.; Aiki, H.; Kato, M.; Masunaga, H.; Smedstad, L. F.; Katsumata, M.; Yoneyama, K.; Higuchi, A.; Tsuboki, K.; Uyeda, H.

    2012-12-01

    We develop a three-dimensional atmosphere-ocean regional coupled-model with cloud-permitting scale; the atmosphere part is Cloud Resolving Storm Simulator (CReSS) and the ocean one is Non Hydrostatic Ocean model for the Earth Simulator (NHOES). This study shows results of daily simulation over the CINDY/DYNAMO observation region using CReSS-NHOES. Three types of sensitivity experiment are carried out to clarify the effect of the two-way coupled simulation and horizontal grid resolutions. One is the CReSS-NHOES two-way coupled simulation with horizontal grid spacing of 0.045 degree (approximately 4.8 km). Another two simulations are the CReSS simulations without coupling NHOES with horizontal grid spacing of 0.045 and 0.0225 degrees (approximately 2.4 km). The Global Spectral Model (GSM: Horizontal grid resolution is approximately 50 km) data provided by Japan Meteorological Agency (JMA) are used as the initial and boundary conditions of the atmosphere in CReSS and CReSS-NHOES. Three-dimensional Navy Coastal Ocean Model (NCOM) data provided by Naval Research Laboratory are used as the initial and boundary conditions of the ocean in CReSS-NHOES. The daily simulation is carried out for 36 hours from 12 UTC from October 1, 2011 to January 31, 2012 almost every day. We reproduce approximately 30-day surface pressure perturbation that should be related to the Madden-Julian Oscillation, half-day surface pressure perturbation that is related to the atmospheric tide, and the existence of low equivalent potential temperature airmass in the middle troposphere at a fixed observation point of the R/V Mirai (80.5E, 8S). However, the sharp vertical gradient of temperature and salinity at the bottom of the ocean mixed layer at the same point cannot be reproduced. The sensitivity of the coupling of the ocean model is not critical, because the difference of area-averaged sea surface temperature, sensible and latent heat fluxes from the sea surface is quite small. This should be attributed to the short-time scale (36 hours) simulation over the tropical ocean. In addition, the simulated frequency of upper (middle/low) clouds calculated using Satellite Data Simulator Unit (SDSU) is greater (lesser) than the observed one obtained by the METEOSAT.

  13. Direct human influence on atmospheric CO2 seasonality from increased cropland productivity

    NASA Astrophysics Data System (ADS)

    Gray, Josh M.; Frolking, Steve; Kort, Eric A.; Ray, Deepak K.; Kucharik, Christopher J.; Ramankutty, Navin; Friedl, Mark A.

    2014-11-01

    Ground- and aircraft-based measurements show that the seasonal amplitude of Northern Hemisphere atmospheric carbon dioxide (CO2) concentrations has increased by as much as 50 per cent over the past 50 years. This increase has been linked to changes in temperate, boreal and arctic ecosystem properties and processes such as enhanced photosynthesis, increased heterotrophic respiration, and expansion of woody vegetation. However, the precise causal mechanisms behind the observed changes in atmospheric CO2 seasonality remain unclear. Here we use production statistics and a carbon accounting model to show that increases in agricultural productivity, which have been largely overlooked in previous investigations, explain as much as a quarter of the observed changes in atmospheric CO2 seasonality. Specifically, Northern Hemisphere extratropical maize, wheat, rice, and soybean production grew by 240 per cent between 1961 and 2008, thereby increasing the amount of net carbon uptake by croplands during the Northern Hemisphere growing season by 0.33 petagrams. Maize alone accounts for two-thirds of this change, owing mostly to agricultural intensification within concentrated production zones in the midwestern United States and northern China. Maize, wheat, rice, and soybeans account for about 68 per cent of extratropical dry biomass production, so it is likely that the total impact of increased agricultural production exceeds the amount quantified here.

  14. Direct human influence on atmospheric CO2 seasonality from increased cropland productivity.

    PubMed

    Gray, Josh M; Frolking, Steve; Kort, Eric A; Ray, Deepak K; Kucharik, Christopher J; Ramankutty, Navin; Friedl, Mark A

    2014-11-20

    Ground- and aircraft-based measurements show that the seasonal amplitude of Northern Hemisphere atmospheric carbon dioxide (CO2) concentrations has increased by as much as 50 per cent over the past 50 years. This increase has been linked to changes in temperate, boreal and arctic ecosystem properties and processes such as enhanced photosynthesis, increased heterotrophic respiration, and expansion of woody vegetation. However, the precise causal mechanisms behind the observed changes in atmospheric CO2 seasonality remain unclear. Here we use production statistics and a carbon accounting model to show that increases in agricultural productivity, which have been largely overlooked in previous investigations, explain as much as a quarter of the observed changes in atmospheric CO2 seasonality. Specifically, Northern Hemisphere extratropical maize, wheat, rice, and soybean production grew by 240 per cent between 1961 and 2008, thereby increasing the amount of net carbon uptake by croplands during the Northern Hemisphere growing season by 0.33 petagrams. Maize alone accounts for two-thirds of this change, owing mostly to agricultural intensification within concentrated production zones in the midwestern United States and northern China. Maize, wheat, rice, and soybeans account for about 68 per cent of extratropical dry biomass production, so it is likely that the total impact of increased agricultural production exceeds the amount quantified here. PMID:25409830

  15. Regional behaviour of atmospheric aerosols over Indo-Gangetic Basin during pre-monsoon

    NASA Astrophysics Data System (ADS)

    Tiwari, S.; Singh, A. K.

    2013-05-01

    Atmospherics aerosols play a vital role in the field of study of Earth's radiation budget and their impact on climate change. The present study was carried out for the study of variation of aerosol characteristics during pre-monsoon season 2011 at different locations, (a) Jaipur (26.900 N, 75.900E), (b) Kanpur (26.40 N, 80.40 E) and (c) Gandhi College, Ballia (25.8° N, 84.2°E) over Indo Gangetic Basin (IGB) using AERONET level 1.5 data. Various interesting results are discussed in present paper in terms of aerosol optical and radiative properties.

  16. Land-Atmosphere Interaction in a Semiarid Region: The Bunny Fence Experiment.

    NASA Astrophysics Data System (ADS)

    Lyons, T. J.; Schwerdtfeger, P.; Hacker, J. M.; Foster, I. J.; Smith, R. C. G.; Xinmei, Huang

    1993-07-01

    Southwestern Australia, with a semiarid Mediterranean climate, has been extensively cleared of native vegetation for winter-growing agricultural species The resultant reduction in evapotranspiration has increased land salinisation. Through detailed meteorological and vegetation measurements over both agricultural and native vegetation, the bunny fence experiment is addressing the impact on the climate of replacing native perennial vegetation with winter-growing annual species. Such measurements will give a better understanding of the interaction between the land surface and the atmosphere and are important for improved parameterization of the boundary layer in climate models.

  17. A simple algorithm to estimate the effective regional atmospheric parameters for thermal-inertia mapping

    USGS Publications Warehouse

    Watson, K.; Hummer-Miller, S.

    1981-01-01

    A method based solely on remote sensing data has been developed to estimate those meteorological effects which are required for thermal-inertia mapping. It assumes that the atmospheric fluxes are spatially invariant and that the solar, sky, and sensible heat fluxes can be approximated by a simple mathematical form. Coefficients are determined from least-squares method by fitting observational data to our thermal model. A comparison between field measurements and the model-derived flux shows the type of agreement which can be achieved. An analysis of the limitations of the method is also provided. ?? 1981.

  18. Climate responses to a doubling of atmospheric carbon dioxide for a climatically vulnerable region

    E-print Network

    Snyder, Mark A.

    temperature increasing everywhere in the region annually (up to 3.8°C), and in every month, with the greatest monthly surface warming at high elevations. Snow accumulation decreased everywhere, and precipitation) [Cal. Dept. of Water Resources, 199

  19. Atmospheric input of nitrogen to the coastal region of southeastern Texas 

    E-print Network

    Shon, Zang-Ho

    1994-01-01

    and this enhanced nitrogen affected the concentration of nitrogen species in College Station rain when the air mass came from the southern direction. In the coastal region (Galveston), concentrations of DIN and DON were significantly affected by marine sources...

  20. The effect of meso-scale flows on regional and long-range atmospheric transport in the western Mediterranean area

    NASA Astrophysics Data System (ADS)

    Millán, M. M.; Artíñano, B.; Alonso, L.; Navazo, M.; Castro, M.

    Experimental evidence accumulated over the years indicates that the formation of the Iberian thermal low on summer days is intimately associated with complex dispersion behavior of atmospheric pollutants emitted within the whole of Spain and in particular for those emitted in the coastal areas. The project "Mesometeorological Cycles of Air Pollution in the Iberian Peninsula", sponsored by the CEC, is intended to study the origin and evolution of the atmospheric circulations responsible for the observed behaviour, and document their importance in Spain and in the Mediterranean basin as a whole. To characterize the processes involved, tall stack plumes from four sites in Spain have been tracked with COSPEC remote sensors and used as tracers of opportunity of the flow at their level. This information is being combined with available historical meteorological data to compose a mosaic of atmospheric circulation patterns for the whole of the Iberian peninsula and surrounding regions. The analysis performed to date confirms that: (a) the formation of the thermal low on summer days forces an inward flow of the coastal emissions towards the central plateau, (b) this convergence occurs at the peninsular level, (c) the inflow is mostly ageostrophic and strongly channelled along natural mountain passes, and (d) the marine airmass pulled inland along the Spanish east coast is highly enriched with O 3. The latter, (d), appears to indicate that a compensatory flow to the thermal low is provided by subsidence over the colder waters of the Gulf of Lyon and northwestern Mediterranean area. In turn, this favors the formation of northeasterly winds along the Spanish east coast during the night, and may explain the O 3 levels as a result of regional transport of precursors from source regins in this general area.

  1. The VAMOS Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx): Goals, platforms, and field operations

    SciTech Connect

    Wood, R.; Springston, S.; Mechoso, C. R.; Bretherton, C. S.; A.Weller, R.; Huebert, B.; Straneo, F.; Albrecht, B. A.; Coe, H.; Allen, G.; Vaughan, G.; Daum, P.; Fairall, C.; Chand, D.; Klenner, L. G.; Garreaud, R.; Grados, C.; Covert, D. S.; Bates, T. S.; Krejci, R.; Russell, L. M.; Szoeke, S. d.; Brewer, A.; Yuter, S. E.; Chaigneau, A.; Toniazzo, T.; Minnis, P.; Palikonda, R.; Abel, S. J.; Brown, W. O. J.; Williams, S.; Fochesatto, J.; Brioude, J.; Bower, K. N

    2011-01-21

    The VAMOS Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx) was an international field program designed to make observations of poorly understood but critical components of the coupled climate system of the southeast Pacific. This region is characterized by strong coastal upwelling, the coolest SSTs in the tropical belt, and is home to the largest subtropical stratocumulus deck on Earth. The field intensive phase of VOCALS-REx took place during October and November 2008 and constitutes a critical part of a broader CLIVAR program (VOCALS) designed to develop and promote scientific activities leading to improved understanding, model simulations, and predictions of the southeastern Pacific (SEP) coupled ocean-atmosphere-land system, on diurnal to interannual timescales. The other major components of VOCALS are a modeling program with a model hierarchy ranging from the local to global scales, and a suite of extended observations from regular research cruises, instrumented moorings, and satellites. The two central themes of VOCALS-REx focus upon (a) links between aerosols, clouds and precipitation and their impacts on marine stratocumulus radiative properties, and (b) physical and chemical couplings between the upper ocean and the lower atmosphere, including the role that mesoscale ocean eddies play. A set of hypotheses designed to be tested with the combined field, monitoring and modeling work in VOCALS is presented here. A further goal of VOCALS-REx is to provide datasets for the evaluation and improvement of large-scale numerical models. VOCALS-REx involved five research aircraft, two ships and two surface sites in northern Chile. We describe the instrument payloads and key mission strategies for these platforms and give a summary of the missions conducted.

  2. Sensitivity of Boreal-Summer Circulation and Precipitation to Atmospheric Aerosols in Selected Regions: Part I Africa and India

    SciTech Connect

    Sud, Yogesh C.; Wilcox, Eric; Lau, William K.; Walker, Greg K.; Liu, Xiaohong; Nenes, Athanasios; Lee , Dongmin; Kim, K. - M.; Zhou, Yaping; Bhattacharjee, P. S.

    2009-10-23

    Version-4 of the Goddard Earth Observing System (GEOS-4) General Circulation Model (GCM) was employed to assess the influence of potential changes in aerosols on the regional circulation, ambient temperatures, and precipitation in four selected regions: India and Africa (current paper), as well as North and South America (companion paper). Ensemble-simulations were carried out with the GCM to assess the aerosol direct and indirect effects, hereafter ADE and AIE. Each simulation was started from the NCEP-analyzed initial conditions for May 1 and was integrated through May-June-July-August of each year: 1982-1987 to provide an ensemble set of six simulations. In the first set, called the baseline experiment (#1), climatological aerosols were prescribed. The next two experiments (#2 and #3) had two sets of simulations each: one with 2X and another with 1/2X the climatological aerosols over each of the four selected regions. In experiment#2, the anomaly regions were advectively restricted (AR), i.e., the large-scale prognostic fields outside the aerosol anomaly regions were prescribed while in experiment#3, the anomaly regions were advectively Interactive (AI) as is the case in a normal GCM integrations, but with the same aerosols anomalies as in experiment #2. Intercomparisons of circulation, diabatic heating, and precipitation difference fields showed large disparities among the AR and AI simulations, which raised serious questions about the AR assumption, commonly invoked in regional climate simulation studies. Consequently AI simulation mode was chosen for the subsequent studies. Two more experiments (#4 and #5) were performed in the AI mode in which ADE and AIE were activated one at a time. The results showed that ADE and AIE work in concert to make the joint influences larger than sum of each acting alone. Moreover, the ADE and AIE influences were vastly different for the Indian and Africa regions, which suggest an imperative need to include them rationally in climate models. We also found that the aerosol induced increase of tropical cirrus clouds would potentially offset any cirrus thinning that may occur due to global warming in response to CO2 increase.

  3. Separating the influence of temperature, drought, and fire on interannual variability in atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Keppel-Aleks, Gretchen; Wolf, Aaron S.; Mu, Mingquan; Doney, Scott C.; Morton, Douglas C.; Kasibhatla, Prasad S.; Miller, John B.; Dlugokencky, Edward J.; Randerson, James T.

    2014-11-01

    The response of the carbon cycle in prognostic Earth system models (ESMs) contributes significant uncertainty to projections of global climate change. Quantifying contributions of known drivers of interannual variability in the growth rate of atmospheric carbon dioxide (CO2) is important for improving the representation of terrestrial ecosystem processes in these ESMs. Several recent studies have identified the temperature dependence of tropical net ecosystem exchange (NEE) as a primary driver of this variability by analyzing a single, globally averaged time series of CO2 anomalies. Here we examined how the temporal evolution of CO2 in different latitude bands may be used to separate contributions from temperature stress, drought stress, and fire emissions to CO2 variability. We developed atmospheric CO2 patterns from each of these mechanisms during 1997-2011 using an atmospheric transport model. NEE responses to temperature, NEE responses to drought, and fire emissions all contributed significantly to CO2 variability in each latitude band, suggesting that no single mechanism was the dominant driver. We found that the sum of drought and fire contributions to CO2 variability exceeded direct NEE responses to temperature in both the Northern and Southern Hemispheres. Additional sensitivity tests revealed that these contributions are masked by temporal and spatial smoothing of CO2 observations. Accounting for fires, the sensitivity of tropical NEE to temperature stress decreased by 25% to 2.9 ± 0.4 Pg C yr-1 K-1. These results underscore the need for accurate attribution of the drivers of CO2 variability prior to using contemporary observations to constrain long-term ESM responses.

  4. Separating the influence of temperature, drought, and fire on interannual variability in atmospheric CO2

    PubMed Central

    Keppel-Aleks, Gretchen; Wolf, Aaron S; Mu, Mingquan; Doney, Scott C; Morton, Douglas C; Kasibhatla, Prasad S; Miller, John B; Dlugokencky, Edward J; Randerson, James T

    2014-01-01

    The response of the carbon cycle in prognostic Earth system models (ESMs) contributes significant uncertainty to projections of global climate change. Quantifying contributions of known drivers of interannual variability in the growth rate of atmospheric carbon dioxide (CO2) is important for improving the representation of terrestrial ecosystem processes in these ESMs. Several recent studies have identified the temperature dependence of tropical net ecosystem exchange (NEE) as a primary driver of this variability by analyzing a single, globally averaged time series of CO2 anomalies. Here we examined how the temporal evolution of CO2 in different latitude bands may be used to separate contributions from temperature stress, drought stress, and fire emissions to CO2 variability. We developed atmospheric CO2 patterns from each of these mechanisms during 1997–2011 using an atmospheric transport model. NEE responses to temperature, NEE responses to drought, and fire emissions all contributed significantly to CO2 variability in each latitude band, suggesting that no single mechanism was the dominant driver. We found that the sum of drought and fire contributions to CO2 variability exceeded direct NEE responses to temperature in both the Northern and Southern Hemispheres. Additional sensitivity tests revealed that these contributions are masked by temporal and spatial smoothing of CO2 observations. Accounting for fires, the sensitivity of tropical NEE to temperature stress decreased by 25% to 2.9?±?0.4 Pg C yr?1?K?1. These results underscore the need for accurate attribution of the drivers of CO2 variability prior to using contemporary observations to constrain long-term ESM responses.

  5. Evaluation of the Impact of Atmospheric Infrared Sounder (AIRS) Radiance and Profile Data Assimilation in Partly Cloudy Regions

    NASA Technical Reports Server (NTRS)

    Zavodsky, Bradley; Srikishen, Jayanthi; Jedlovec, Gary

    2013-01-01

    Improvements to global and regional numerical weather prediction have been demonstrated through assimilation of data from NASA s Atmospheric Infrared Sounder (AIRS). Current operational data assimilation systems use AIRS radiances, but impact on regional forecasts has been much smaller than for global forecasts. Retrieved profiles from AIRS contain much of the information that is contained in the radiances and may be able to reveal reasons for this reduced impact. Assimilating AIRS retrieved profiles in an identical analysis configuration to the radiances, tracking the quantity and quality of the assimilated data in each technique, and examining analysis increments and forecast impact from each data type can yield clues as to the reasons for the reduced impact. By doing this with regional scale models individual synoptic features (and the impact of AIRS on these features) can be more easily tracked. This project examines the assimilation of hyperspectral sounder data used in operational numerical weather prediction by comparing operational techniques used for AIRS radiances and research techniques used for AIRS retrieved profiles. Parallel versions of a configuration of the Weather Research and Forecasting (WRF) model with Gridpoint Statistical Interpolation (GSI) are run to examine the impact AIRS radiances and retrieved profiles. Statistical evaluation of 6 weeks of forecast runs will be compared along with preliminary results of in-depth investigations for select case comparing the analysis increments in partly cloudy regions and short-term forecast impacts.

  6. On the influence of the atmospheric dust on the zodiacal light polarization

    NASA Technical Reports Server (NTRS)

    Divari, N. B.; Krylova, S. N.

    1973-01-01

    Three color observations of the nightglow brightness and polarization were made to determine the brightness of zodiacal light at the ecliptic pole. On the assumption that the degree of polarization of zodiacal light is 0.20 at the ecliptic pole, the corresponding brightnesses are found to be 68, 70, and 96 G2 stars of the 10th magnitude per square deg. at 0.37, 0.53, and 0.58 micron. The large diurnal variations in observed intensity and direction of polarization are attributed to the effects of dust in the earth's atmosphere.

  7. Changes in atmospheric CO2 - Influence of the marine biota at high latitude

    NASA Technical Reports Server (NTRS)

    Knox, F.; Mcelroy, M. B.

    1984-01-01

    Approximately half of the nitrogen and phosphorus entering deep waters of the contemporary ocean are transported from the surface in inorganic form as preformed nutrients. A simple model for ocean chemistry is presented and shown to account for the present level of atmospheric CO2. Fluctuations in preformed nutrients, modulated by changes in insolation and circulation at high latitudes, can result in significant variations in CO2. It is suggested that these changes may account for the apparent control on climate exercised by secular variations in the orbital parameters of the earth.

  8. Influence of clouds and diffuse radiation on ecosystem-atmosphere CO2 and CO18

    E-print Network

    Noone, David

    of transpiration on canopy relative humidity and leaf water. Photosynthesis and isofluxes were both reduced radiation, photosynthesis, and relative humidity. Citation: Still, C. J., et al. (2009), Influence of clouds CO2 to flux, humidity, and isotope hydrol- ogy changes, manuscript in preparation, 2009], fundamental

  9. Influence of elevated atmospheric CO2 concentration on common weeds in Scandinavian agriculture

    Microsoft Academic Search

    Arne Saebø; Leiv M. Mortensen

    1998-01-01

    This study investigated the influence of elevated CO2 on three perennial weed species (Achillea millefolium, Leontodon autumnalis and Rumex acetosa) and seven annual species (Chenopodium album, Matricaria matricarioides, Poa annua, Polygoniini persicaria, Senecio vulgaris, Spergula arvensis and Stellaria media). The study was carried out during the period 3 May to 5 August in ten field chamber units of 9 m

  10. Factors and sources influencing ionic composition of atmospheric condensate during winter season in lower troposphere over Delhi, India.

    PubMed

    Kumar, Pawan; Yadav, Sudesh

    2013-03-01

    Atmospheric condensate (AC) and rainwater samples were collected during 2010-2011 winter season from Delhi and characterized for major cations and anions. The observed order of abundance of cations and anions in AC samples was NH (4) (+) ?>?Ca(2+)?>?Na(+)?>?K(+)?>?Mg(2+) and HCO (3) (-) ?>?SO (4) (2-) ?>?Cl(-)?>?NO (2) (-) ?>?NO (3) (-) ?>?F(-), respectively. All samples were alkaline in nature and ? (cation)/? (anion) ratio was found to be close to one. NH (4) (+) emissions followed by Ca(2+) and Mg(2+) were largely responsible for neutralization of acidity caused by high NO( x ) and SO(2) emissions from vehicles and thermal power plants in the region. Interestingly, AC samples show low nitrate content compared with its precursor nitrite, which is commonly reversed in case of rainwater. It could be due to (1) slow light-mediated oxidation of HONO; (2) larger emission of NO(2) and temperature inversion conditions entrapping them; and (3) formation and dissociation of ammonium nitrite, which seems to be possible as both carry close correlation in our data set. Principal component analysis indicated three factors (marine mixed with biomass burning, anthropogenic and terrestrial, and carbonates) for all ionic species. Significantly higher sulfate/nitrate ratio indicates greater anthropogenic contributions in AC samples compared with rainwater. Compared with rainwater, AC samples show higher abundance of all ionic species except SO(4), NO(3), and Ca suggesting inclusion of these ions by wash out process during rain events. Ionic composition and related variations in AC and rainwater samples indicate that two represent different processes in time and space coordinates. AC represents the near-surface interaction whereas rainwater chemistry is indicative of regional patterns. AC could be a suitable way to understand atmospheric water interactions with gas and solid particle species in the lower atmosphere. PMID:22740157

  11. Meteor matter interaction with the Earth's atmosphere and the ionospheric E-region structure

    NASA Technical Reports Server (NTRS)

    Alimov, O.

    1987-01-01

    The exploration of the ionospheric E region is a pressing problem, both in the applied and fundamental studies. Results are presented of an investigation: (1) to estimate the meteor ionization contribution to the night time E layer and influx; (2) to study the phenomenon of intensive sporadic layer formation following cessation of meteor stream activity; and (3) to access the role of metallic ions of meteor origin in the diurnal and seasonal variations in the occurrence probabilities of midlatitude E sub s. The contribution was evaluated of meteor matter, Lyman radiation and corpuscular particles to the electron concentration of the night E region. Results are discussed.

  12. Reliability of moss ( Hylocomium splendens and Pleurozium schreberi) as a bioindicator of atmospheric chemistry in the Barents region: Interspecies and field duplicate variability

    Microsoft Academic Search

    J. H Halleraker; C Reimann; P de Caritat; T. E Finne; G Kashulina; H Niskaavaara; I Bogatyrev

    1998-01-01

    As part of a collaborative ecogeochemical mapping project in the European Arctic, the terrestrial mosses Hylocomium splendens (Hs) and Pleurozium schreberi (Pl) have been used to document atmospheric chemistry. The regional importance of the variability of interspecies and field duplicate samples on the element distribution in the central Barents region has been calculated. Of the 36 elements studied, 17 have

  13. Atmospheric submicron aerosol composition and particulate organic nitrate formation in a boreal forestland-urban mixed region

    NASA Astrophysics Data System (ADS)

    Hao, L. Q.; Kortelainen, A.; Romakkaniemi, S.; Portin, H.; Jaatinen, A.; Leskinen, A.; Komppula, M.; Miettinen, P.; Sueper, D.; Pajunoja, A.; Smith, J. N.; Lehtinen, K. E. J.; Worsnop, D. R.; Laaksonen, A.; Virtanen, A.

    2014-12-01

    The Puijo aerosol-cloud observation station is a unique measurement site for its location in the mixed region between the boreal forestland and the municipality of Kuopio, Finland. A measurement campaign was carried out at the station during fall 2010. An Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-Tof-AMS) was deployed to characterize the atmospheric submicron aerosols. Positive matrix factorization (PMF) was applied to the unified high-resolution mass spectra organic species with NO+ and NO2+ ions to discover the intrinsic relationships between the organic and inorganic species and their daily cycles. On average, the submicron aerosols in this study were dominated by organic and sulfate species, composing 48.2 and 28.7% of total observed aerosol mass, respectively, with smaller contributions from ammonium (9.3%), nitrate (4.9%), chloride (0.8%) and BC (8.1%). The sources of these species included the primary emissions originating from the city area, secondary formation from both natural and anthropogenic emissions and regional transport. The PMF analysis succeeded in separating the mixed organic and inorganic spectra into three distinct organic and one inorganic factors. For organic factors, the semi-volatile oxygenated organic aerosol (SVOOA) and low-volatility oxygenated OA (LVOOA) accounted for 54.8 and 36.3% of total organic masses, respectively, while the hydrocarbon-like organic aerosol (HOA) accounted for 8.9% of total organics, with its main source from urban emissions. The inorganic factor is identified as NH4NO3, comprising 6.9% of the fitted aerosol mass by PMF. Based on the PMF results, the nitrate species were separated into organic and inorganic components, with the organic nitrates contributing one-third of the total nitrate mass. The results highlight both anthropogenic and biogenic emissions as important atmospheric aerosol sources in a forest-urban mixed region.

  14. Assessing the influence of local sources on POPs in atmospheric depositions and sediments near Trento (Italy)

    NASA Astrophysics Data System (ADS)

    Argiriadis, E.; Rada, E. C.; Vecchiato, M.; Zambon, S.; Ionescu, G.; Schiavon, M.; Ragazzi, M.; Gambaro, A.

    2014-12-01

    The content of five classes of Persistent Organic Pollutants (POPs) in the atmospheric depositions and sediments of an area interested by a steelmaking plant, a state highway and urban settlements were investigated. Samples were collected through a wet and dry sampler onto the roof of a primary school or core drilled from the sediments of a nearby pond and analyzed for PCDD/Fs, PCBs, PAHs, PBDEs and PCNs in order to assess the role of different sources on direct emissions in atmosphere and transfer to other environmental compartments. The method was tested with reference materials, laboratory and field blanks. The results show higher fluxes of POPs in winter depositions, with PAH levels up to 6500 ng m-2 d-1. Patterns and diagnostic ratios suggest that the main sources are fuel and wood combustion. PCDD/Fs are present at background level, with maximum total fluxes of 17 pg m-2 d-1 in depositions and concentrations of 7 pg g-1 in sediments. All concentrations peak at mid-level in the sediment core and then decrease towards surface, as an effect of regulatory limitations and update to modern industrial technologies.

  15. Accretion influences cooling of neutron star atmospheres during type-I X-ray bursts

    NASA Astrophysics Data System (ADS)

    Kajava, J.; N"attil"a, J.; Latvala, O.; Pursiainen, M.; Poutanen, J.; Suleimanov, V.; Revnivtsev, M.; Kuulkers, E.; Galloway, D.

    2014-07-01

    Observations of type-I X-ray bursts provide a way of measuring neutron star (NS) masses and radii. The derived mass-radius values depend on the colour-correction factor of the NS photosphere, the photospheric chemical composition and the distance. We have studied 11 bursting low-mass X-ray binaries (LMXB) with RXTE/PCA. We find a correlation between the time evolution of the apparent NS radii during the early cooling phases of X-ray bursts and the spectral properties of the persistent emission before the bursts. NS atmosphere models predict that the colour-correction factor decreases in the early cooling phases when the emitted luminosity drops from the Eddington value. Therefore, the apparent NS radii should be variable during this phase as it depends on this factor. We find that the model predictions agree with the data only when X-ray bursts occur during the hard (island) state of LMXBs. We take this as evidence that the accretion flow - that surrounds the NS - changes the photospheric colour-correction factor during the soft (banana) states, where the atmosphere model predictions never agree with the data. This finding is important as even slight variations in the colour-correction factors cause large errors in the derived neutron star radii.

  16. The influence of atmospheric circulation on the occurrence of hail in the North German Lowlands

    NASA Astrophysics Data System (ADS)

    Katarzyna, Suwa?a

    2013-05-01

    The atmospheric circulation and thermal conditions in the troposphere were analysed to identify the situations which are conductive to hail development in the North German Lowlands. They were established on the basis of the data obtained from the US National Center for Environmental Prediction/US National Center for Atmospheric Research Reanalysis database, and they included sea level pressure, 500 hPa geopotential height, the temperature at 850 and 500 hPa and HYSPLIT backward trajectories model. Daily information about hail occurrence in 16 selected stations was received from Deutscher Wetterdienst database and it covered the years 1951-2010. It was found that hail in the studied area was connected with large negative anomalies of the sea level pressure over Scandinavia and, consequently, the northwestern direction of air mass influx. In some cases, hail was associated with the northern influx, with strong negative anomalies of the temperature, and with positive anomalies of the temperature during the southern influx of air masses.

  17. A simple method for estimating the influence of eroding soil profiles on atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Billings, S. A.; Buddemeier, R. W.; Richter, D. deB.; Van Oost, K.; Bohling, G.

    2010-06-01

    Although soil erosion has often been considered a net source of atmospheric carbon (C), several recent studies suggest that erosion serves as a net C sink. We have developed a spreadsheet-based model of soil organic C dynamics within an eroding profile (Soil Organic Carbon, Erosion, Replacement, and Oxidation (SOrCERO)) that calculates effects of soil organic carbon (SOC) erosion and altered SOC oxidation and production on the net exchange of C between the eroding profile and atmosphere. SOrCERO suggests that erosion can induce a net C sink or source, depending on management practices, the extent to which SOC oxidation and production characteristics change with erosion, and the fate of eroded SOC. Varying these parameters generated a wide range of C source and sink estimates (maximum net source and sink of 1.1/3.1 Pg C yr-1 respectively, applying results globally), highlighting research needs to constrain model estimates. We invite others to download SOrCERO (http://www.kbs.ku.edu/people/staff_www/billings/index.html) to test conceptual models and eroding soil profiles of interest in a consistent, comparable fashion.

  18. Increases in atmospheric CO2 have little influence on transpiration of a temperate forest canopy.

    PubMed

    Tor-ngern, Pantana; Oren, Ram; Ward, Eric J; Palmroth, Sari; McCarthy, Heather R; Domec, Jean-Christophe

    2015-01-01

    Models of forest energy, water and carbon cycles assume decreased stomatal conductance with elevated atmospheric CO2 concentration ([CO2]) based on leaf-scale measurements, a response not directly translatable to canopies. Where canopy-atmosphere are well-coupled, [CO2 ]-induced structural changes, such as increasing leaf-area index (LD), may cause, or compensate for, reduced mean canopy stomatal conductance (GS), keeping transpiration (EC) and, hence, runoff unaltered. We investigated GS responses to increasing [CO2] of conifer and broadleaved trees in a temperate forest subjected to 17-yr free-air CO2 enrichment (FACE; + 200 ?mol mol(-1)). During the final phase of the experiment, we employed step changes of [CO2] in four elevated-[CO2 ] plots, separating direct response to changing [CO2] in the leaf-internal air-space from indirect effects of slow changes via leaf hydraulic adjustments and canopy development. Short-term manipulations caused no direct response up to 1.8 × ambient [CO2], suggesting that the observed long-term 21% reduction of GS was an indirect effect of decreased leaf hydraulic conductance and increased leaf shading. Thus, EC was unaffected by [CO2] because 19% higher canopy LD nullified the effect of leaf hydraulic acclimation on GS . We advocate long-term experiments of duration sufficient for slow responses to manifest, and modifying models predicting forest water, energy and carbon cycles accordingly. PMID:25346045

  19. A REGIONAL ATMOSPHERIC FATE AND TRANSPORT MODEL FOR ATRAZINE, PART I: DEVELOPMENT AND IMPLEMENTATION

    EPA Science Inventory

    The Community Multiscale Air Quality (CMAQ) modeling system is adapted to simulate the regional transport and fate of atrazine, one of the most widely used herbicides in the United States. Model chemistry and deposition are modified, and a gas-to-particle partitioning algorithm...

  20. Sodium density and atmospheric temperature in the mesopause region in polar summer

    Microsoft Academic Search

    H. Kurzawa; U. von Zahn

    1990-01-01

    Sodium lidar measurements have been performed during three summer seasons at a polar latitude (69 deg N), yielding profiles of sodium number density and temperature of the 85-100 km altitude region. Density measurements were performed during the months of June-August; temperature measurements only were made in August. The sodium layer was found to be both significantly weaker and more variable

  1. Atmospheric effects and societal consequences of regional scale nuclear conflicts and acts of individual nuclear terrorism

    Microsoft Academic Search

    O. B. Toon; R. P. Turco; A. Robock; C. Bardeen; L. Oman; G. L. Stenchikov

    2007-01-01

    We assess the potential damage and smoke production associated with the detonation of small nuclear weapons in modern megacities. While the number of nuclear warheads in the world has fallen by about a factor of three since its peak in 1986, the number of nuclear weapons states is increasing and the potential exists for numerous regional nuclear arms races. Eight

  2. Atmospheric effects and societal consequences of regional scale nuclear conflicts and acts of individual nuclear terrorism

    Microsoft Academic Search

    O. B. Toon; R. P. Turco; A. Robock; C. Bardeen; L. Oman; G. L. Stenchikov

    2006-01-01

    We assess the potential damage and smoke production associated with the detonation of small nuclear weapons in modern megacities. While the number of nuclear warheads in the world has fallen by about a factor of three since its peak in 1986, the number of nuclear weapons states is increasing and the potential exists for numerous regional nuclear arms races. Eight

  3. The role of atmospheric planetary-scale waves in the D region winter anomaly

    Microsoft Academic Search

    Y. Muraoka; K. Petzoldt; K. Labitzke

    1986-01-01

    Characteristics of the D region winter anomaly are examined, by using ionospheric data along a meridian chain of stations near Japan. The data were obtained by means of long-distance VLF radio wave propagation and HF radio wave vertical sounding. Interesting features are the equatorward extension of the anomaly and the variability of its duration. These features are further discussed in

  4. Modeling the influence of land surface flux on the regional climate of the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Ma, Weiqiang; Ma, Yaoming

    2015-05-01

    Land surface heat fluxes over the heterogeneous landscape of the Tibetan Plateau can serve as boundary conditions for modeling the regional climate and the Asian monsoon system. The Weather Research and Forecasting (WRF) atmospheric modeling system has enabled us to model the land surface heat flux through sensitivity experiments that utilize in situ observation data and the regional land-atmosphere exchanges of water and heat fluxes that are foundational to understanding the water and energy cycles present during the Asian monsoon period. A series of sensitivity experiments based on the WRF model and field observations has been proposed and tested for deriving the land surface heat fluxes (surface net radiation flux, soil heat flux, sensible heat flux, and latent heat flux) over a heterogeneous land surface. The sensitivity experiments were simulated over the field area of the Coordinated Enhanced Observing Period Asia-Australia Monsoon Project on the Tibetan Plateau (CEOP-CAMP/Tibet), located on the northern Tibetan Plateau of China. A WRF modeling period from July to August 2007 was selected for the summer monsoon conditions. To validate the modeling results, the ground-measured or calculated variables (e.g., net radiation flux, soil heat flux, sensible heat flux, and latent heat flux) were compared to the simulated values. The modeling results show that the derived model land surface heat fluxes are in agreement with the land surface observations over the study area in summer. Therefore, the WRF model sensitivity experiments were successful in simulating the land surface heat fluxes over the study area.

  5. Region of influence regression for estimating the 50-year flood at ungaged sites

    USGS Publications Warehouse

    Tasker, Gary D.; Hodge, S.A.; Barks, C.S.

    1996-01-01

    Five methods of developing regional regression models to estimate flood characteristics at ungaged sites in Arkansas are examined. The methods differ in the manner in which the State is divided into subrogions. Each successive method (A to E) is computationally more complex than the previous method. Method A makes no subdivision. Methods B and C define two and four geographic subrogions, respectively. Method D uses cluster/discriminant analysis to define subrogions on the basis of similarities in watershed characteristics. Method E, the new region of influence method, defines a unique subregion for each ungaged site. Split-sample results indicate that, in terms of root-mean-square error, method E (38 percent error) is best. Methods C and D (42 and 41 percent error) were in a virtual tie for second, and methods B (44 percent error) and A (49 percent error) were fourth and fifth best.

  6. Using Dynamically Coupled Turbine/Wind Simulations to Investigate the Influence of Atmospheric Turbulence in Turbine Wake Recovery

    NASA Astrophysics Data System (ADS)

    Koo, E.; Linn, R.; Bossert, J. A.; Kelley, N. D.; Lundquist, J. K.

    2011-12-01

    Ambient atmospheric turbulence interacts with spinning turbines, which modify the intensity and spectra of the turbulence. This turbine-influenced turbulent wind field creates the environment surrounding downstream turbines in a wind farm, thus controlling the amount of wind energy available for harvesting as well as the nature of aerodynamic loads on the blades which cause wear-and-tear of the wind turbines. The conditions to which downstream turbines are exposed, their productivity, and potentially their lifespan is a function of their position within the turbulent wake of upstream turbines. In order to increase our efficiency of energy capture in wind farms and optimize turbine arrangements for both off-shore and terrestrial settings where the wind conditions can be very different, it is essential to understand the influences that various environmental conditions have on the turbulence within wind farms. It is important to find ways of studying the evolution of turbulence as it interacts with turbines and as it advects downstream. It is also important to connect properties of the turbulence with the dynamic and heterogeneous nature of the loads that are applied to turbine blades. Unfortunately, full-scale wind turbine experiments are costly and it is extremely difficult to analyze the dynamic evolution of the full three-dimensional flow field upwind and downwind of wind turbines for a broad set of operating conditions. Numerical simulation tools can be used to perform preliminary investigation of turbine wake flow fields, thus guiding and helping interpret measurement schemes for the limited number of experiments that will be performed. By using numerical models to study the influence of different ambient conditions for different turbine spacing it is possible to develop a better understanding of how terrestrial experiments might relate to off-shore conditions where experiments are more difficult. A numerical technique, WindBlade, has been developed for characterizing the interaction of spinning wind turbines and unsteady/heterogeneous atmospheric boundary layers at length scales ranging from blade-chord scale (meters) to turbine-array scale (multiple kilometers). With this range of resolution WindBlade has been used to investigate the evolution of turbulent flow patterns within multi-turbine arrays. Turbulent kinetic energy, elements of the Reynolds Stress matrix, and the turbulent spectra illustrate the nature of the anisotropic turbulence that occurs due to interaction of turbines and planetary boundary layer wind shear. Comparisons of these data as well as blade loads and power output illustrate the influence of the ambient turbulent scales and the strength of ambient shear upstream of a multi turbine array and rate at which turbine induced turbulence over shadows ambient conditions.

  7. Atmospheric dust

    NSDL National Science Digital Library

    University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

    2003-01-01

    What is the purpose of dust in the atmosphere? On this activity page, part of an interactive laboratory series for grades 8-12, students read about the need for dust in the atmosphere as an agent for condensation. The addition of dust particles to the atmosphere by airplanes introduces students to the concept of cloud seeding and influencing the chance of rain in an area. Copyright 2005 Eisenhower National Clearinghouse

  8. A Possible Influence of Solar System Dynamics on the Circulation of the Mars Atmosphere

    NASA Astrophysics Data System (ADS)

    Shirley, J. H.

    2014-12-01

    The inter-annual variability of the Mars atmosphere is dominated by the occasional occurrence of global-scale dust storms (GDS) in the southern summer season. The intermittent occurrence of such storms represents a major unsolved problem of atmospheric physics. To aid in studying these events, we have compiled a catalog of Mars years including such storms (n=9) and Mars years without global-scale storms (n=11) through the year 2013. We use these samples to explore the question of a possible relationship linking GDS occurrence with the variability of the orbital angular momentum of Mars with respect to the solar system barycenter (LMars). We find that a remarkably simple and direct relationship links the occurrence and non-occurrence of GDS on Mars with the variability of this dynamical quantity. All of the GDS became planet encircling during periods when LMars was increasing or near maxima. Statistical significance is obtained for the clustering tendencies of LMars waveform phases for key subsets of the catalog, including the mid-season storms (as defined below) and the years without storms. A systematic progression is found in the phasing of the LMars waveforms with respect to the annual cycle of solar irradiance for the following three GDS categories: The early season GDS (1977 and 2001, initiating near Ls=204° and Ls=185° respectively), the mid-season storms (1956, 1971, 1982, 1994, and 2007; Ls=208° through Ls=262°), and the late season GDS (1924 and 1973, Ls=310° and Ls=300°). Rising values of LMars immediately prior to and during the Mars dust storm season appear to be a necessary (but not sufficient) condition for the initiation of GDS events. Factors internal to the Mars climate system, including the spatial redistribution of dust from year to year, also appear to play an important role in determining whether a GDS may occur in any particular Mars year. A testable physical hypothesis has recently been formulated, and an effort is now underway to more fully quantify and characterize the response of the Mars atmosphere to this aspect of solar system dynamical variability [Mischna et al., this meeting]. This work was performed at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. Copyright 2014, all rights reserved.

  9. Explaining the temporal clustering of UK flooding: large-scale atmospheric influences

    NASA Astrophysics Data System (ADS)

    Waterhouse, E. K.; Vitolo, R.; Lane, S. N.; Stephenson, D. B.

    2009-04-01

    Natural catastrophes are particularly threatening for the insurance industry when they occur in temporal clusters, that is groups of events within a short time period. We present work combining knowledge and techniques from two distinct disciplines, hydrology and meteorology, to explore the role of large-scale atmospheric flow patterns in the temporal clustering of floods in the UK. The UK floods that occurred in the summer of 2007 provide the context for this research. These floods were due to three distinct high-intensity rainfall events in June and July 2007, during a wet summer that affected much of the country. Together, the North of England floods in June and the Central England floods in July resulted in the largest flood-related insured losses in the UK (est. £3 billion). The summer floods were deemed unusual due to their wide spatial extent and rapid succession. However, devastating flooding in the UK has been common in recent years (e.g. autumn 2000 in Northern England; July 2002 in Glasgow, January 2005 in Carlisle; and recently, during the 2008 summer in the North East of England). Examination of the longest historical flow records in the UK, dating back to the 1800s, reveals that this flood-rich period follows a relatively dry, flood-poor period from the 1960s until the late 1990s. To understand and predict the probability of flood clustering and flood-rich periods, we study the effect of low-frequency atmospheric and climatic factors in driving high river flows and flood events. Previous work shows that temporal variations in large-scale atmospheric patterns explain winter storm clustering through changes in the tracks of North Atlantic extratropical cyclones towards and over Europe. We use the following teleconnection indices as predictors in a Poisson regression model for threshold exceedances: the North Atlantic Oscillation and the East Atlantic Pattern (obtained by Principal Component Analysis of the geopotential field) and the Atlantic Multidecadal Oscillation. The long-term goal of this research is to achieve improved understanding of flood clustering, for use in CAT models for more comprehensive, multi-hazard hydro-meteorological risk assessment. Here, we present results from the initial stages of this project.

  10. Experimental Research on the Influence of Wind Turbine Blade Rotation on the Characteristics of Atmospheric Discharges

    Microsoft Academic Search

    Branko M. Radi?evi?; Milan S. Savi?

    2011-01-01

    The experimental research, whose most important segments are described in this paper, is one of the first attempts to determine the influence of wind turbine blade rotation on like- lihood of getting struck by lightning. The tests were conducted in the high-voltage laboratory, applying the up-and-down method for determination of the 50% flashover standard switching voltage. The impulse voltage waves

  11. Estimating the fractal dimension of the atmosphere and the predictability via Lyapunov exponents for the Caribbean region

    NASA Astrophysics Data System (ADS)

    Chadee, X. T.

    2007-05-01

    The fractal dimension, Lyapunov-exponent spectrum, and predictability are analyzed for chaotic attractors in the atmosphere by analyzing the time series of daily wind speeds over the Caribbean region. It can be shown that this dimension is greater than 8. However, the number of data points may be too small to obtain a reliable estimate of the Grassberger-Procaccia (1983a) correlation dimension because of the limitations discussed by Ruelle (1990). These results lead us to claim that there probably exist no low-dimensional strange attractors in the atmosphere. Because the fractal dimension has not yet been saturated, the Kolmogorov entropy and the error-doubling time obtained by the method of Grassberger and Procaccia (1983b) are sensitive to the selection of the time delay and are thus unreliable. A practical and more reliable method for estimating the Kolmogorov entropy and error-doubling time involves the computation of the Lyapunov-exponent spectrum using the algorithm of Zeng et al. (1991). Using this method, it is found that the error-doubling time is 2-3 days for time series over the Caribbean region. This is comparable to the predictability time found by Waelbrock (1995) for a single station in Mexico. The predictability time over land is slightly less than that over ocean which tends to have higher climatic signal-to-noise ratio. This analysis impacts on the selection of prediction tools (deterministic chaotic linear and non-linear maps or linear stochastic modeling) for wind speeds in the short term for wind energy farm resource planning and management. We conclude that short term wind predictions in the Caribbean region, for a few days ahead, may be best done with a stochastic model instead of a deterministic chaotic model. References Grassberger, P., and I. Procaccia. 1983a. Measuring the strangeness of attractors. Physica D 9: 189-208. Grassberger, P., and I. Procaccia. 1983b. Estimating the Kolmogorov entropy from a chaotic signal. Phys. Rev. A. 28: 2591-2593. Ruelle, D. 1990. Deterministic chaos: the science and the fiction. Proc. Royal Soc. Lond. A 427: 241-248. Waelbrock, H. 1995. Deterministic chaos in tropical atmospheric dynamics. J. Atmos. Sci. 52: 2404-2415. Zeng, X., R. Eykholt, and R. A. Pielke. 1991. Estimating the Lyapunov-exponent spectrum from short time series of low precision. Phys. Rev. Lett. 66: 3229-3232.

  12. Influence of Global Atmospheric Change on the Feeding Behavior and Growth Performance of a Mammalian Herbivore, Microtus ochrogaster

    PubMed Central

    Habeck, Christopher W.; Lindroth, Richard L.

    2013-01-01

    Global atmospheric change is influencing the quality of plants as a resource for herbivores. We investigated the impacts of elevated carbon dioxide (CO2) and ozone (O3) on the phytochemistry of two forbs, Solidago canadensis and Taraxacum officinale, and the subsequent feeding behavior and growth performance of weanling prairie voles (Microtus ochrogaster) feeding on those plants. Plants for the chemical analyses and feeding trials were harvested from the understory of control (ambient air), elevated CO2 (560 µl CO2 l?1), and elevated O3 (ambient × 1.5) rings at the Aspen FACE (Free Air CO2 Enrichment) site near Rhinelander, Wisconsin. We assigned individual voles to receive plants from only one FACE ring and recorded plant consumption and weanling body mass for seven days. Elevated CO2 and O3 altered the foliar chemistry of both forbs, but only female weanling voles on the O3 diet showed negative responses to these changes. Elevated CO2 increased the fiber fractions of both plant species, whereas O3 fumigation elicited strong responses among many phytochemical components, most notably increasing the carbon-to-nitrogen ratio by 40% and decreasing N by 26%. Consumption did not differ between plant species or among fumigation treatments. Male voles were unaffected by the fumigation treatments, whereas female voles grew 36% less than controls when fed O3-grown plants. These results demonstrate that global atmospheric change has the potential to affect the performance of a mammalian herbivore through changes in plant chemistry. PMID:23977345

  13. Passive landfill gas emission - Influence of atmospheric pressure and implications for the operation of methane-oxidising biofilters.

    PubMed

    Gebert, Julia; Groengroeft, Alexander

    2006-01-01

    A passively vented landfill site in Northern Germany was monitored for gas emission dynamics through high resolution measurements of landfill gas pressure, flow rate and composition as well as atmospheric pressure and temperature. Landfill gas emission could be directly related to atmospheric pressure changes on all scales as induced by the autooscillation of air, diurnal variations and the passage of pressure highs and lows. Gas flux reversed every 20 h on average, with 50% of emission phases lasting only 10h or less. During gas emission phases, methane loads fed to a connected methane oxidising biofiltration unit varied between near zero and 247 g CH4 h(-1)m(-3) filter material. Emission dynamics not only influenced the amount of methane fed to the biofilter but also the establishment of gas composition profiles within the biofilter, thus being of high relevance for biofilter operation. The duration of the gas emission phase emerged as most significant variable for the distribution of landfill gas components within the biofilter. PMID:16387238

  14. Regional estimation of soil C stocks and CO2 emissions as influenced by cropping systems and soil type

    NASA Astrophysics Data System (ADS)

    Farina, Roberta; Marchetti, Alessandro; Di Bene, Claudia

    2015-04-01

    Soil organic matter (SOM) is of crucial importance for agricultural soil quality and fertility. At global level soil contains about three times the carbon stored in the vegetation and about twice that present in the atmosphere. Soil could act as source and sink of carbon, influencing the balance of CO2 concentration and consequently the global climate. The sink/source ratio depends on many factors that encompass climate, soil characteristics and different land management practices. Thus, the relatively large gross exchange of GHGs between atmosphere and soils and the significant stocks of carbon in soils, may have significant impact on climate and on soil quality. To quantify the dynamics of C induced by land cover change and the spatial and temporal dynamics of C sources and sinks at regional and, potentially, at national and global scales, we propose a methodology, based on a bio-physical model combined with a spatial explicit database to estimate C stock changes and emissions/removals. The study has been conducted in a pilot region in Italy (Apulia, Foggia province), considering the typical cropping systems of the area, namely rainfed cereals, tomato, vineyard and olives. For this purpose, the model RothC10N (Farina et al., 2013), that simulates soil C dynamics, has been modified to work directly in batch using data of climate, soil (over 290 georeferenced soil profiles), annual agriculture land use (1200 observations) The C inputs from crops have been estimated using statistics and data from literature. The model was run to equilibrium for each point of soil, in order to make all the data homogeneous in terms of time. The obtained data were interpolate with geostatisical procedures, obtaining a set of 30x30 km grid with the initial soil C. The new layer produced, together with soil and land use layers, were used for a long-term run (12 years). Results showed that olive groves and vineyards were able to stock a considerable amount of C (from 0.4 to 1.5 t ha-1 y-1). The continuous wheat lead to a reduction of C stock, ranging from 0.1 to 0.2 t ha-1 y-1, in sandy and clayey soils respectively. When the cereal rotation included irrigated tomato the C stock decline was about 0.4 t ha-1 y-1. In terms of emissions of CO2 the release to atmosphere was in average 6.5, 4.4, 3.6 and 3.3 t ha-1 y-1 for wheat-irrigated tomato rotation, continuous wheat, vineyards and olive groves respectively. The method proposed to estimate at regional level the C stocks and emissions has proved to be efficient and could be used to supply key information for climate and agricultural policies.

  15. Influence of SSTs over Nino-3.4 Region on the Indian Summer Monsoon Rainfall

    NASA Astrophysics Data System (ADS)

    Wilson, S. S.; Gleixner, S.; K, M.

    2014-12-01

    Indian Summer Monsoon Rainfall (ISMR) is sensitive to SST variations in the Pacific Ocean. In this study, the correlation coefficients between the SST in the Nino-3.4 region of season (June-August) and ISMR are evaluated using the datasets ERSST v3b and ISMR data (www.tropmet.res.in). An analysis of the mean monthly data of 64 years (1955-2013) reveals that the relationship between the SST in the Nino-3.4 region in June-August and the ISMR is changed after 1983. Seven drought years were reported between 1955 and 1983 and the warmest SST is in the equatorial eastern Pacific. After 1983, the warmest SST is shifted towards the central Pacific region during drought years. The coldest region in the central Pacific during wet years is shifted towards the eastern Pacific after 1983. The position of the sensitive area in the Pacific Ocean thus influences the drought/wet which is found to be changed in the recent epoch.

  16. The Single Scattering Albedo of Martian Atmospheric Dust in the 290-500 nm Region

    NASA Astrophysics Data System (ADS)

    Wolff, M. J.; Bell, J. F.; Sohl-Dickstein, J.

    2002-12-01

    Despite multiple previous investigations, the detailed wavelength-dependence of Martian atmospheric dust absorption at ultraviolet (UV) and near-UV wavelengths is not particularly well-known. Several efforts have made some progress (e.g., Pang and Ajello, Icarus, 30, 63, 1977; Clancy et al., JGR, 100, 5251, 1995; Wolff et al., JGR, 104, 9027, 1999), but observational or instrumental constraints have severely limited the amount of detail retrievable. Ideally, one would observe an isolated dust signature with moderate spectral resolution and adequate spectral coverage. In essence, one would like to obtain data of a large-scale, optically-thick dust storm with a well-calibrated spacecraft-based spectrometer. Such a set of data has very recently been obtained, albeit somewhat fortuitously. Using the Hubble Space Telescope and the Space Telescope Imaging Spectrograph (STIS) instrument to perform high resolution imaging spectroscopy of Mars during the 2001 opposition, the combination of an electronics failure and an unusually early onset of a global dust storm, we have observations of Martian atmospheric dust with a minimal-to-undetectable surface contribution. Our 2001 observations utilized the G430L grating to cover 289 to 590 nm at 0.27 nm/channel. The STIS 0.2 arcec slit was pushbroom-scanned across the 13-16 arcsec diameter planet in ~70 adjacent steps, yielding a 3-dimensional image cube in 1024 wavelengths and at ~20x80 km spatial resolution per spectrum. This was done during four visits on 2001 August 9, 10, 14, and September 4 (LS=211°\\ to 227°). We will present the derived dust absorption spectra (i.e., single scattering albedo) which has resulted from our multiple-scattering, radiative transfer analyses of the STIS data. Our results will be compared to analogous efforts of Goguen et al. (personal communication, 2002) using nearly-contemporaneous observations in the 230-300 nm range (STIS/G230L). In addition, in order to better constrain the dust properties (e.g., size, shape) and subsequently isolate the single scattering albedo, our work includes retrievals from Mars Global Surveyor Thermal Emission Spectrometer observations (both the thermal infrared and solar-band channel).

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

    NASA Astrophysics Data System (ADS)

    Zemankova, K.; Huszar, P.

    2009-12-01

    Coupling of regional climate model RegCM (Pal et al., 2007) and atmospheric chemistry/aerosols model CAMx (Environ, 2006) is being developed at our department under the CECILIA project (EC 6th FP) with the aim to study climate forcing due to atmospheric chemistry/aerosols on regional scale. Regional climate model RegCM with the resolution of 10 km drives transport, chemistry and dry/wet deposition of the CAMx model being operated on the Central and Eastern European domain and consequently the radiative active agents from the CAMx model enter the radiative transfer schemes for the calculation of heating rate changes in the regional climate model. In order to increase the accuracy of land cover data in this model system, a new input dataset has been prepared and used for the calculation of emissions of volatile organic compounds (VOCs) from natural sources. This dataset is mainly based on the single tree species database from the european project of JRC in Ispra - Agriculture, Forestry, and Other Land Uses in Europe (AFOLU) which covers most of the model domain. For the locations where AFOLU data were not available, i.e. basically non-EU areas, the USGS Eurasia land cover database has been used. Both databases are available in 1 km resolution. Emission factors for new land cover categories were obtained either from the laboratory measurements or from the literature. The Guenther et al. (1995) model algorithm has been used for the calculation of biogenic VOC (BVOC) emission fluxes. Effects of new land cover and BVOC emission data on the CAMx model simulations of low level ozone in the year 2000 have been studied. Improvement of model results when compared with the measured data may be seen, especially in the simulation of extreme values such as ozone summer maxima. References: - ENVIRON Corp., 2006. CAMx User’s Guide, version 4.40 - Guenther A., Hewitt N., Erickson D., Fall R., Geron Ch., Graedel T., Harley P., Klinger L., Lerdau M., McKay W. A., Pierce T., Scholes B., Steinbrecher R., Tallamraju R., Taylor J., Zimmerman P., 1995. Global model of natural organic compound emissions. J. Geophys. Res. 100, 8873-8892. - Pal, J. S., Giorgi, F., Bi, X., Elguindi, N., Solomon, F., Gao, X., Rauscher, S. A., Francisco, R., Zakey, A., Winter, J., Ashfaq, M., Syed, F. S., Bell, J. L., Diffenbaugh, N. S., Karmacharya, J., Konare, A., Martinez, D., da Rocha, R. P., Sloan, L. C., and Steiner, A. L., 2007. Regional climate modeling for the developing world: The ICTP RegCM3 and RegCNET, B. Am. Meteor. Soc., 88, 1395-1409.

  18. Influence of reaction atmosphere and solvent on biochar yield and characteristics.

    PubMed

    Marx, S; Chiyanzu, I; Piyo, N

    2014-07-01

    Sunflower husks were converted to biochar via thermochemical liquefaction in different solvents and reaction atmospheres. Highest biochar yields obtained was 574 g kg(-1) husks. Surface area of the produced chars and evolution of aromatic compounds in the biochar structure increased with an increase in temperature. Volatile matter and N-content decreased and S-content decreased significantly with an increase in temperature which is favourable should the biochars be used for combustion. The HHV of the biochars were significantly higher than that of the feedstock as was also indicated by the energy densification ratio. The biochars compared favourable with coal on a Van Krevelen diagram, showing the possibility of the biochars for application in co-gasification. CO2 performed better in retaining the energy of the feedstock in the biochar (up to 58%). It was shown that sunflower husks are a viable feedstock for the production of biochars for application in co-gasification or combustion. PMID:24859208

  19. Influence of natural extracts on the shelf life of modified atmosphere-packaged pork patties.

    PubMed

    Lorenzo, José M; Sineiro, Jorge; Amado, Isabel R; Franco, Daniel

    2014-01-01

    In this study four natural extracts from tea (TEA), grape (GRA), chestnut (CHE) and seaweed (SEA) with potential antioxidant activity were evaluated in pork patties. During 20 days of storage in modified atmosphere packs at 2°C, pH, colour, lipid oxidation and microbial spoilage parameters of raw minced porcine patties were examined and compared with a synthetic antioxidant (BHT) and control (CON) batch. Due to their higher polyphenol content, GRA and TEA extracts were the most effective antioxidants against lipid oxidation, also limiting colour deterioration. In addition, both natural extracts led to a decrease of total viable counts (TVC), lactic acid bacteria (LAB), Pseudomonas and psychotropic aerobic bacteria compared to the control. Among the four natural compounds tested, tea and grape extracts showed the most potential as alternatives to commercial antioxidants, for increasing the quality and extending the shelf-life of porcine patties. PMID:24008060

  20. The influence of water table depth and the free atmospheric state on convective rainfall predisposition

    NASA Astrophysics Data System (ADS)

    Bonetti, Sara; Manoli, Gabriele; Domec, Jean-Christophe; Putti, Mario; Marani, Marco; Katul, Gabriel G.

    2015-04-01

    A mechanistic model for the soil-plant system is coupled to a conventional slab representation of the atmospheric boundary layer (ABL) to explore the role of groundwater table (WT) variations and free atmospheric (FA) states on convective rainfall predisposition (CRP) at a Loblolly pine plantation site situated in the lower coastal plain of North Carolina. Predisposition is quantified using the crossing between modeled lifting condensation level (LCL) and convectively grown ABL depth. The LCL-ABL depth crossing is necessary for air saturation but not sufficient for cloud formation and subsequent convective rainfall occurrence. However, such crossing forms the main template for which all subsequent dynamical processes regulating the formation (or suppression) of convective rainfall operate on. If the feedback between surface fluxes and FA conditions is neglected, a reduction in latent heat flux associated with reduced WT levels is shown to enhance the ABL-LCL crossing probability. When the soil-plant system is fully coupled with ABL dynamics thereby allowing feedback with ABL temperature and humidity, FA states remain the leading control on CRP. However, vegetation water stress plays a role in controlling ABL-LCL crossing when the humidity supply by the FA is within an intermediate range of values. When FA humidity supply is low, cloud formation is suppressed independent of surface latent heat flux. Similarly, when FA moisture supply is high, cloud formation can occur independent of surface latent heat flux. In an intermediate regime of FA moisture supply, the surface latent heat flux controlled by soil water availability can supplement (or suppress) the necessary water vapor leading to reduced LCL and subsequent ABL-LCL crossing. It is shown that this intermediate state corresponds to FA values around the mode in observed humidity lapse rates ?w (between -2.5 × 10-6 and -1.5 × 10-6 kg kg-1m-1), suggesting that vegetation water uptake may be controlling CRP at the study site.

  1. Observations of an atmospheric chemical equator and its implications for the tropical warm pool region

    NASA Astrophysics Data System (ADS)

    Hamilton, Jacqueline F.; Allen, Grant; Watson, Nicola M.; Lee, James D.; Saxton, Julie E.; Lewis, Alastair C.; Vaughan, Geraint; Bower, Keith N.; Flynn, Michael J.; Crosier, Jonathan; Carver, Glenn D.; Harris, Neil R. P.; Parker, Robert J.; Remedios, John J.; Richards, Nigel A. D.

    2008-10-01

    This paper reports observations of a tropospheric chemical equator in the Western Pacific region during the Austral monsoon season, separating the polluted Northern Hemisphere from the cleaner Southern Hemisphere. Measurements of carbon monoxide, ozone, aerosol size/composition, and non-methane hydrocarbons were made from aircraft, flying north from Darwin, Australia as part of the Aerosol and Chemical Transport In tropical conVEction (ACTIVE) campaign. A chemical equator, defined as a sharp gradient in the chemical background, was found not to be coincident with the Intertropical Convergence Zone during this period. A pronounced interfacial region was identified between 8.5 and 10°S, where tracer mixing ratios increased rapidly within the boundary layer, e.g. CO from 40 ppbv to 160 ppbv within 0.5° latitude (50 km), with inhibited inter-hemispheric mixing. These measurements are discussed in context using a combination of meteorological and Earth-observing satellite imagery, back trajectory analysis and chemical model data with the conclusion that air flowing into and subsequently uplifted by the active convection of the Tropical Warm Pool (TWP) region in the Western Pacific is likely to be highly polluted, and will perturb the composition of the Tropical Tropopause Layer. The main source of CO and other pollutants within the TWP region is expected to be biomass burning, with extensive fires in North Sumatra and Thailand during this period. The sharp gradient in composition at the chemical equator seen here results from extensive burning to the north, contrasting with pristine maritime air advected from the Southern Indian Ocean by a strong land-based cyclone over the Northern Territory of Australia.

  2. Modeling and Analysis of Global and Regional Climate Change in Relation to Atmospheric Hydrologic Processes

    NASA Technical Reports Server (NTRS)

    Johnson, Donald R.

    2001-01-01

    This research was directed to the development and application of global isentropic modeling and analysis capabilities to describe hydrologic processes and energy exchange in the climate system, and discern regional climate change. An additional objective was to investigate the accuracy and theoretical limits of global climate predictability which are imposed by the inherent limitations of simulating trace constituent transport and the hydrologic processes of condensation, precipitation and cloud life cycles.

  3. Observed Scaling in Clouds and Precipitation and Scale Incognizance in Regional to Global Atmospheric Models

    SciTech Connect

    O'Brien, Travis A.; Li, Fuyu; Collins, William D.; Rauscher, Sara; Ringler, Todd; Taylor, Mark; Hagos, Samson M.; Leung, Lai-Yung R.

    2013-12-01

    We use observations of robust scaling behavior in clouds and precipitation to derive constraints on how partitioning of precipitation should change with model resolution. Our analysis indicates that 90-99% of stratiform precipitation should occur in clouds that are resolvable by contemporary climate models (e.g., with 200 km or finer grid spacing). Furthermore, this resolved fraction of stratiform precipitation should increase sharply with resolution, such that effectively all stratiform precipitation should be resolvable above scales of ~50 km. We show that the Community Atmosphere Model (CAM) and the Weather Research and Forecasting (WRF) model also exhibit the robust cloud and precipitation scaling behavior that is present in observations, yet the resolved fraction of stratiform precipitation actually decreases with increasing model resolution. A suite of experiments with multiple dynamical cores provides strong evidence that this `scale-incognizant' behavior originates in one of the CAM4 parameterizations. An additional set of sensitivity experiments rules out both convection parameterizations, and by a process of elimination these results implicate the stratiform cloud and precipitation parameterization. Tests with the CAM5 physics package show improvements in the resolution-dependence of resolved cloud fraction and resolved stratiform precipitation fraction.

  4. A statistical study of F region ion temperatures at high latitudes based on Atmosphere Explorer C data

    NASA Technical Reports Server (NTRS)

    St.-Maurice, J.-P.; Hanson, W. B.

    1984-01-01

    The ion-energy balance in the high-latitude F region was studied using 40,000 simultaneous ion-temperature and drift measurements on Atmosphere Explorer C. The large number of measurements revealed how the mean ion temperature, and the average deviation from that mean, change as a function of ion drift speed during solar-minimum conditions. It was found that, in spite of an apparent large scatter in the data, the measurements could always be reasonably explained in terms of fluctuations in the neutral dynamical properties, to which the ion energy is coupled. The results also provide evidence for increased neutral drifts as the ion E x B drift increases. Evidence for systematic ion-drag effects can also be found, on the average, for dc electric fields stronger than 60 mV/m.

  5. The Influence of Photolysis Rate Constants in Ozone Production for the Paso del Norte Region

    NASA Astrophysics Data System (ADS)

    Becerra, Fernando; Fitzgerald, Rosa

    2012-03-01

    In this research work we are focusing on understanding the relationship between photolysis rates and the photochemical ozone changes observed in the Paso del Norte region. The city of El Paso, Texas together with Ciudad Juarez, Mexico, forms the largest contiguous bi-national metropolitan area. This region suffers year-round ozone pollution events, and a better understanding is needed to mitigate them. Previous studies have found that ambient ozone concentrations tend to be higher on weekends rather than on weekdays, this phenomenon being referred to, as the ``weekend effect.'' If the ozone standard is exceeded more frequently on weekends, then this phenomenon must be considered in the design of ozone control strategies. In this work we investigate some of the most representative weekend ozone episodes at El Paso, TX, during the years 2009, 2010 and 2011 using the ozone photolysis rates. In this research the TUV radiative-transfer model is used to calculate the local photolysis rates and a UV MFRSR instrument is used to obtain experimental parameters. Seasonal variations and the weekday-weekend effect is studied. The results of this research will help to understand the underlying behavior of the photolysis rate constants when different atmospheric conditions are present.

  6. Polycyclic aromatic hydrocarbons study in atmospheric fine and coarse particles using diagnostic ratios and receptor model in urban/industrial region.

    PubMed

    Teixeira, Elba Calesso; Mattiuzi, Camila Dalla Porta; Agudelo-Castañeda, Dayana Milena; Garcia, Karine de Oliveira; Wiegand, Flavio

    2013-11-01

    Atmospheric fine and coarse particles were collected in Teflon filters in three cities of the region of the Lower Sinos River Basin of Rio Grande do Sul in the year 2010. The filters were Soxhlet extracted, and 14 priority PAHs were analyzed using a gas chromatograph coupled to a mass spectrometer (GC/MS). The principal emission sources of these compounds were assessed by using diagnostic ratios and receptor model: positive matrix factorization (PMF 3.0) of the US Environmental Protection Agency. The results of PAHs concentration for the studied year showed significant levels of high molecular weight (HMW) PAH, Ind, and BghiP, in PM2.5 in the winter season, showing the influence of mobile sources. The application of receptor model PMF 3.0 revealed that the main sources of PAHs were vehicle fleet (both diesel and gasoline), followed by coal combustion, wood combustion, and resuspension of dust. The results of the receptor modeling are in agreement with the data obtained by the ratio diagnostic. PMID:23824515

  7. Ultraviolet source for rocket measurements of nitric oxide in the upper atmosphere. [D region

    NASA Technical Reports Server (NTRS)

    Siddiqui, J. M. H.

    1974-01-01

    An ultraviolet source suitable for balloon and rocket payloads for measurements of nitric oxide in the lower D-region of the ionosphere was developed. The source primarily emits 1236 A and 1165 A photons obtained from an R.F.-excited krypton discharge in a resonator of coaxial geometry. Ultraviolet flux output greater than 10 to the 14th power photons/sec can be obtained from this source. A systematic design philosophy is developed which enables the photon output to be optimized with respect to photon wavelength, gas pressure, R.F., resonator geometry, and gas to be used. Critical factors in the design are discussed in detail.

  8. Atmospheric deposition of polybromodiphenyl ethers in remote mountain regions of Europe

    NASA Astrophysics Data System (ADS)

    Arellano, L.; Fernández, P.; López, J. F.; Rose, N. L.; Nickus, U.; Thies, H.; Stuchlik, E.; Camarero, L.; Catalan, J.; Grimalt, J. O.

    2013-08-01

    Polybromodiphenyl ethers (PBDEs) were analyzed in bulk atmospheric deposition collected in four European remote mountain areas over a period of two years (2004-2006): Lake Redon (Pyrenees), Gossenköllesee (Alps), Lochnagar (Grampian Mountains) and Skalnate (Tatras). In all sites, the PBDE distributions were dominated by BDE209. BDE47 and BDE99 were the major low-brominated congeners, followed by BDE100 and BDE183. This composition is consistent with predominant inputs from the commercial mixtures decaBDE and pentaBDE. The total congener site-averaged fluxes ranged between 100 ng m-2 mo-1 (Alps) and 190 ng m-2 mo-1 (Tatras). Significant correlations between PBDE deposition and percent of North Atlantic backwards air mass trajectories in the collected samples of the westernmost sites, Lochnagar and Redon, suggested an impact of transcontinental transfer of these pollutants from North American sources into Europe. Skalnate and, to a lower extent Redon, recorded another main PBDE source from central Europe corresponding to secondary emissions of the penta BDE commercial mixture. The fluxes of these secondary emissions were temperature dependent and correlated to total particle deposition and rainfall. Higher PBDE fluxes were observed at increasing temperature, particle deposition and precipitation. Another specific PBDE source was observed in United Kingdom and recorded in Lochnagar. Photolytic degradation during transport decreased the relative abundance of BDE209 and modified the emitted pentaBDE technical mixtures by depletion of the relative composition of BDE99 and, to a lower extent, BDE47. The transformations were more intense in the sites located above 2000 m, Redon and Gossenköllesee, and, particularly, during the warm periods.

  9. Atmospheric deposition of polybromodiphenyl ethers in remote mountain regions of Europe

    NASA Astrophysics Data System (ADS)

    Arellano, L.; Fernández, P.; López, J. F.; Rose, N. L.; Nickus, U.; Thies, H.; Stuchlik, E.; Camarero, L.; Catalan, J.; Grimalt, J. O.

    2014-05-01

    Polybromodiphenyl ethers (PBDEs) were analyzed in bulk atmospheric deposition collected in four European remote mountain areas over a period of two years (2004-2006): Lake Redon (Pyrenees, Catalonia, Spain), Gossenköllesee (Alps, Austria), Lochnagar (Grampian Mountains, Scotland) and Skalnate (Tatras, Slovakia). In all sites, the PBDE distributions were dominated by BDE209. BDE47 and BDE99 were the major low-brominated congeners, followed by BDE100 and BDE183. This composition is consistent with predominant inputs from the commercial mixtures decaBDE and pentaBDE. The total congener site-averaged fluxes ranged between 100 ng m-2 mo-1 (Alps) and 190 ng m-2 mo-1 (Tatras). Significant correlations between PBDE deposition and percent of North Atlantic backwards air mass trajectories in the collected samples of the westernmost sites, Lochnagar and Redon, suggested an impact of transcontinental transfer of these pollutants from North American sources into Europe. Skalnate, and to a lower extent Redon, recorded another main PBDE source from central Europe corresponding to secondary emissions of the pentaBDE commercial mixture. The fluxes of these secondary emissions were temperature dependent and correlated to total particle deposition and rainfall. Higher PBDE fluxes were observed at increasing temperature, particle deposition and precipitation. Another specific PBDE source was observed in United Kingdom and recorded in Lochnagar. Photolytic degradation during transport decreased the relative abundance of BDE209 and modified the emitted pentaBDE technical mixtures by depletion of the relative composition of BDE99 and, to a lower extent, BDE47. The transformations were more intense in the sites located above 2000 m (Redon and Gossenköllesee) and, particularly, during the warm periods.

  10. Influence of the amount of N2 admixture on the dynamics of atmospheric pressure helium discharges in capillary tubes

    NASA Astrophysics Data System (ADS)

    Bourdon, Anne; Pechereau, Francois; Viegas, Pedro

    2014-10-01

    Since a few years, atmospheric pressure helium microplasma jets ignited in thin dielectric tubes have received considerable interest due to their potential for biomedical applications. In particular, the propagation of discharges in long capillary tubes is studied for the development of medical devices for endoscopic applications. In, experiments have been carried out to study the influence of various amounts of N2 admixture on the characteristics of a helium discharge in long capillary tubes. In this work, we study with a 2D fluid model the discharge characteristics in conditions close to those used in experiments. Simulation results show that the discharge dynamics and structure depend on the amount of N2 admixture and the applied voltage. In particular, as the amount of N2 admixture increases, the propagation velocity of the discharge in the tube first increases and then decreases, as observed in experiments. To explain these results, a detailed analysis of the kinetic scheme of He-N2 mixtures with various amounts of N2 is presented. The influence of other parameters as the initial preionization level, the tube material and the shape of the applied voltage are also discussed.

  11. The influence of water vapor content on electrical and spectral properties of an atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Nikiforov, A. Yu; Sarani, A.; Leys, Ch

    2011-02-01

    An atmospheric pressure plasma jet generated in Ar with water vapor is investigated. It is shown that an increase in the water content results in a decrease in the input power and asymmetry of the current waveform on positive and negative half-periods of the applied voltage. Space-resolved spectroscopy with a resolution of 1 mm and an imaging technique are applied for the characterization of the afterglow and investigation of the influence of water content on plasma properties. The rotational temperature of the jet is determined by simulation of the OH radical emission spectrum, transition A 2?+(v = 0) ? X 2?(v = 0). It is revealed that the temperature of the discharge increases from 450 K (Ar) up to 850 K with an increase in the water content up to 7600 ppm. Generation of the discharge in mixtures of argon with water vapor at a concentration of 350 ppm results in a maximal yield of OH radicals that can be useful in plasma jet applications. Preliminary tests of polypropylene surface modification are carried out in order to estimate the influence of water content on the results of treatment.

  12. Syngas production from tar reforming by microwave plasma jet at atmospheric pressure: power supplied influence

    NASA Astrophysics Data System (ADS)

    de Souza Medeiros, Henrique; Justiniano, Lucas S.; Gomes, Marcelo P.; Soares da Silva Sobrinho, Argemiro; Petraconi Filho, Gilberto

    2013-09-01

    Now a day, scientific community is searching for new fuels able to replace fossil fuels with economic and environment gains and biofuel play a relevant rule, mainly for the transport sector. A major process to obtaining such type of renewable resource is biomass gasification. This process has as product a gas mixture containing CO, CH4, and H2 which is named synthesis gas (syngas). However, an undesirable high molecular organic species denominated tar are also produced in this process which must be removed. In this work, results of syngas production via tar reforming in the atmospheric pressure microwave discharge having as parameter the power supply. Argon, (argon + ethanol), and (argon + tar solution) plasma jet were produced by different values of power supplied (from 0.5 KW to 1.5 KW). The plasma compounds were investigated by optical spectroscopy to each power and gas composition. The main species observed in the spectrum are Ar, CN, OII, OIV, OH, H2, H(beta), CO2, CO, and SIII. This last one came from tar. The best value of the power applied to syngas production from tar reforming was verified between 1.0 KW and 1.2 KW. Now a day, scientific community is searching for new fuels able to replace fossil fuels with economic and environment gains and biofuel play a relevant rule, mainly for the transport sector. A major process to obtaining such type of renewable resource is biomass gasification. This process has as product a gas mixture containing CO, CH4, and H2 which is named synthesis gas (syngas). However, an undesirable high molecular organic species denominated tar are also produced in this process which must be removed. In this work, results of syngas production via tar reforming in the atmospheric pressure microwave discharge having as parameter the power supply. Argon, (argon + ethanol), and (argon + tar solution) plasma jet were produced by different values of power supplied (from 0.5 KW to 1.5 KW). The plasma compounds were investigated by optical spectroscopy to each power and gas composition. The main species observed in the spectrum are Ar, CN, OII, OIV, OH, H2, H(beta), CO2, CO, and SIII. This last one came from tar. The best value of the power applied to syngas production from tar reforming was verified between 1.0 KW and 1.2 KW. We thank the following institutions for financial support: CNPq, CAPES, and FAPESP.

  13. The influence of water vapor on atmospheric exchange measurements with an ICOS* based Laser absorption analyzer

    NASA Astrophysics Data System (ADS)

    Bunk, Rüdiger; Quan, Zhi; Wandel, Matthias; Yi, Zhigang; Bozem, Heiko; Kesselmeier, Jürgen

    2014-05-01

    Carbonyl sulfide and carbon monoxide are both atmospheric trace gases of high interest. Recent advances in the field of spectroscopy have enabled instruments that measure the concentration of the above and other trace gases very fast and with good precision. Increasing the effective path length by reflecting the light between two mirrors in a cavity, these instruments reach impressive sensitivities. Often it is possible to measure the concentration of more than one trace gas at the same time. The OCS/CO2 Analyzer by LGR (Los Gatos Research, Inc.) measures the concentration of water vapor [H2O], carbonyl sulfide [COS], carbon dioxide [CO2] and carbon monoxide [CO] simultaneously. For that the cavity is saturated with light, than the attenuation of light is measured as in standard absorption spectroscopy. The instrument proved to be very fast with good precision and to be able to detect even very low concentrations, especially for COS (as low as 30ppt in the case of COS). However, we observed a rather strong cross sensitivity to water vapor. Altering the water vapor content of the sampled air with two different methods led to a change in the perceived concentration of COS, CO and CO2. This proved especially problematic for enclosure (cuvette) measurements, where the concentrations of one of the above species in an empty cuvette are compared to the concentration of another cuvette containing a plant whose exchange of trace gases with the atmosphere is of interest. There, the plants transpiration leads to a large difference in water vapor content between the cuvettes and that in turn produces artifacts in the concentration differences between the cuvettes for the other above mentioned trace gases. For CO, simultaneous measurement with a UV-Emission Analyzer (AL 5002, Aerolaser) and the COS/CO Analyzer showed good agreement of perceived concentrations as long as the sample gas was dry and an increasing difference in perceived concentration when the sample gas was humidified. The difference in perceived CO concentration showed a clear correlation to the water vapor content in the sample air. For COS we could show that changes in water vapor also impacted on the perceived COS concentrations; the raise of the water vapor concentration would lead to an increasing underestimation of the COS concentration. Drying the air using a Nafion Dryer before entering the COS/CO Analyzer eliminated any water vapor induced artifacts and showed no adverse effects on the quality of the conducted measurements. *Integrated cavity output spectroscopy

  14. The Influence of Atmospheric CO2 Concentration and Climate Variability on Amazon Tropical Forest

    NASA Astrophysics Data System (ADS)

    Castanho, A. D. D. A.; Galbraith, D.; Zhang, K.; Coe, M. T.; Costa, M. H.; Moorcroft, P. R.

    2014-12-01

    Tropical forests are important regulators of atmospheric CO2 concentration and any change in tropical forest C balance will directly affect global climate. Long term studies from undisturbed old-growth forest monitoring sites distributed across Amazonia have presented an overall increase in aboveground biomass in the last decades, and the increase in atmospheric CO2 concentrations is considered the main driver for this observed carbon sink. The main goal of this work was to use simulations from dynamic global vegetation models (DGVM) to explore how much of the observed historical (1970-2008) increase in biomass in undisturbed tropical forest in Amazonia could be attributed to the CO2 fertilization effect or associated to climate change. We compared simulated biomass and productivity from three DGVMs (IBIS, ED2 and JULES) with observations from forest plots (RAINFOR). The analyses helped clarify the variability of historical and potential future simulations.The analyses showed that models shared similar results and deficiencies. The three models represented the two major model types: conventional dynamic global vegetation models that simulate community dynamics and competition between plant functional types (PFTs) using an aggregated 'big-leaf' representation (IBIS and Jules), and a size-and-age structured terrestrial ecosystem model that captures individual scale dynamics and competition (ED2). In general, the ED2 model results were more sensitive to climate, but all models greatly underestimate the impact of extreme climatic events (e.g. drought) compared to field data.All the DGVM's studied tend to simulate the average biomass well and to overestimate productivity of vegetation under current conditions. All the models presented very low spatial variability compared to field observation. The lack of spatial variability of biomass and productivity is attributed to the lack of nutrient and residence time spatial heterogeneity. All of the DGVMs results suggest that forests have gained AGB in the last decades, consistent with the observations. The CO2 fertilization effect is the strongest factor contributing to the increase in biomass followed by climate. However, models failed to simulate observed biomass dynamics at individual sites when compared to individual field sites.

  15. The effect of store name, brand name and store atmosphere on customers' perceived quality-value and store preference in the Udon Thani region of Thailand

    Microsoft Academic Search

    Subchat Untachai

    2007-01-01

    The current study was designed to provide a quantitative measure of the influence of store name, brand name, and store atmospherics on retail preference in a study of the retailing industry in Udon Thani province, Thailand. The objectives of this study are twofold, (I) to examine the extent to which perceived store value is related to store preference, and (2)

  16. Influence of variable rates of neritic carbonate deposition on atmospheric carbon dioxide and pelagic sediments

    NASA Technical Reports Server (NTRS)

    Walker, J. C.; Opdyke, B. C.

    1995-01-01

    Short-term imbalances in the global cycle of shallow water calcium carbonate deposition and dissolution may be responsible for much of the observed Pleistocene change in atmospheric carbon dioxide content. However, any proposed changes in the alkalinity balance of the ocean must be reconciled with the sedimentary record of deep-sea carbonates. The possible magnitude of the effect of shallow water carbonate deposition on the dissolution of pelagic carbonate can be tested using numerical simulations of the global carbon cycle. Boundary conditions can be defined by using extant shallow water carbonate accumulation data and pelagic carbonate deposition/dissolution data. On timescales of thousands of years carbonate deposition versus dissolution is rarely out of equilibrium by more than 1.5 x 10(13) mole yr-1. Results indicate that the carbonate chemistry of the ocean is rarely at equilibrium on timescales less than 10 ka. This disequilibrium is probably due to sea level-induced changes in shallow water calcium carbonate deposition/dissolution, an interpretation that does not conflict with pelagic sedimentary data from the central Pacific.

  17. The possible influence of volcanic emissions on atmospheric aerosols in the city of Colima, Mexico.

    PubMed

    Miranda, Javier; Zepeda, Francisco; Galindo, Ignacio

    2004-01-01

    An elemental composition study of atmospheric aerosols from the City of Colima, in the Western Coast of Mexico, is presented. Samples of PM(15)-PM(2.5) and PM(2.5) were collected with Stacked Filter Units (SFU) of the Davis design, in urban and rural sites, the latter located between the City of Colima and the Volcán de Colima, an active volcano. Elemental analyses were carried out using Particle Induced X-ray Emission (PIXE). The gravimetric mass concentrations for the fine fraction were slightly higher in the urban site, while the mean concentrations in the coarse fraction were equal within the uncertainties. High Cl contents were determined in the coarse fraction, a fact also observed in emissions from the Volcán de Colima by other authors. In addition to average elemental concentrations, cluster analysis based on elemental contents was performed, with wind speed and direction data, showing that there is an industrial contributor to aerosols North of the urban area. Moreover, a contribution from the volcanic emissions was identified from the grouping of S, Cl, Cu, and Zn, elements associated to particles emitted by the Volcán de Colima. PMID:14568726

  18. Cenozoic climate evolution in Asian region and its influence on isotopic composition of precipitation

    NASA Astrophysics Data System (ADS)

    Botsyun, Svetlana; Donnadieu, Yannick; Sepulchre, Pierre; Risi, Camille; Fluteau, Frédéric

    2015-04-01

    The evolution of Asian climate during the Cenozoic as well as the onset of monsoon systems in this area is highly debated. Factors that control climate include the geographical position of continents, the land-sea distribution and altitude of orogens. In tern, several climatic parameters such as air temperature, precipitation amount and isotopic fractionation through mass-dependent processes impact precipitation ?18O lapse rate. Stable oxygen paleoaltimetry is considered to be a very efficient and widely applied technique, but the link between stable oxygen composition of precipitation and climate is not well established. To quantify the influence of paleogeography changes on climate and precipitation ?18O over Asia, the atmospheric general circulation model LMDZ-iso, with embedded stable oxygen isotopes, was used. For more realistic experiments, sea surface temperatures were calculated with the fully coupled model FOAM. Various scenarios of TP growth have been applied together with Paleocene, Eocene, Oligocene and Miocene boundary conditions. The results of our numerical modelling show a significant influence of paleogeography changes on the Asian climate. The retreat of the Paratethys ocean, the changes in latitudinal position of India, and the height of the Tibetan Plateau most likely control precipitation patterns over Asia and cause spatial and temporal isotopic variations linked with the amount effect. Indian Ocean currents restructuring during the Eocene induces a substantial warming over Asian continent. The adiabatic and non-adiabatic temperature effects explain some of ?18O signal variations. We highlight the importance of these multiple factor on paleoelevations estimates derived using oxygen stable isotopes.

  19. Inferring atmospheric variability from the North Atlantic and the Mediterranean region using tree rings and historical archives from the Iberian Peninsula

    NASA Astrophysics Data System (ADS)

    Andreu-Hayles, L.; Ummenhofer, C.; Barriendos, M.; Helle, G.; Schleser, G.; Leuenberger, M.; Gutiérrez, E.; Cook, E. R.

    2013-12-01

    Tree rings are natural archives that can record distinct types of past climate variability depending on the parameters measured providing the same annual resolution (absolute calendar years) than instrumental data and historical archives. Here, we seek to validate different approaches to inferring atmospheric variability combining the information recorded by both natural and historical archives. Our particular study provides a unique opportunity to explore the footprint of Mediterranean and Atlantic influences on several sites across the Iberian Peninsula, and different modes of climate variability for past centuries. We assessed the climatic signal recorded by the tree-ring proxies, the ring-width and stable isotope ratios, and found that measuring stable carbon (?13C) and oxygen (?18O) isotope ratios, that is more expensive and time-consuming than measuring the classical ring-width parameter, provides an added value by better capturing large-scale climatic features than ring-width (see Figure), which is often more dependent on local conditions. These spatial correlations between tree rings and gridded meteorological data also demonstrated that the isotope signatures in the targeted Iberian pine forests are very sensitive to moisture variations during the summer period, and thus can be good indicators of drought variability in this region. Accordingly, composite anomalies during years with extreme high (low) stable isotopic values in the tree-ring records revealed coherent large-scale atmospheric circulation patterns with reduced (enhanced) moisture flux for the different sites. Finally, we explored how extreme events recorded in historical archives and point-by-point regression techniques to reconstruct past climate variability based on tree-rings can extend the study of the North Atlantic and the Mediterranean atmospheric variability to the last 400 years. Spatial correlations between gridded June-July (JJ) GPCC precipitation and tree-ring chronologies from a Pinus uncinata forest in the northeast of the Iberian Peninsula. (a) No significant correlations were found with the tree-ring width chronology. (b) Significant negative correlations over a large area were found with the ?13C tree-ring chronology. This indicates that low precipitation, i.e. drier conditions, would enhance closure of stomata decreasing the intercellular CO2 concentration. This lower CO2 availability in the stomata chambers is consistent with less discrimination against the heavier isotope 13C, and thus leads to high ?13C ratios.

  20. Regional and Local Carbon Flux Information from a Continuous Atmospheric CO2 Network in the Rocky Mountains

    NASA Astrophysics Data System (ADS)

    Heck, S.; Stephens, B.; Watt, A.; Schimel, D.; Aulenbach, S.

    2006-12-01

    We have established a Regional Atmospheric Continuous CO2 Network in the Rocky Mountains (Rocky RACCOON) to improve our understanding of regional carbon fluxes and to fill key gaps in the North American Carbon Program (NACP). There are strong scientific and societal motivations for determining CO2 exchanges on regional scales. Mountain forests in particular represent a significant potential net CO2 sink in the U.S. and are highly sensitive to land-use practices and climate change. We have developed a new autonomous, inexpensive, and robust CO2 analysis system (AIRCOA) and have deployed these systems at 4 sites: Niwot Ridge (NWR), near Ward, Colorado (August, 2005); Storm Peak Laboratory (SPL) near Steamboat Springs, Colorado (September, 2005); Fraser Experimental Forest (FEF), near Fraser Colorado (August, 2005); and Hidden Peak (HDP), near Snowbird, Utah (April, 2006). We will deploy a fifth site in Northeastern Arizona in September 2006. Measurements of surveillance gas cylinders, and an ongoing intercomparison with flask measurements made by NOAA GMD at Niwot Ridge, show measurement biases of 0.2 ppm or better. Preliminary analysis of CO2 variability at our sites provides valuable information on the usefulness of mountaintop observations in data-assimilation and inverse modeling. Comparisons between our sites and to background sites can give direct regional-scale flux estimates, and analysis of the nocturnal CO2 build-ups at FEF provides unique insights into valley-scale respiration rates. We will present results of these preliminary analyses and plans for future integration with the NACP effort.

  1. Taking a different perspective: mindset influences neural regions that represent value and choice.

    PubMed

    Bhanji, Jamil P; Beer, Jennifer S

    2012-10-01

    Most choices are complex and can be considered from a number of different perspectives. For example, someone choosing a snack may have taste, health, cost or any number of factors at the forefront of their mind. Although previous research has examined neural systems related to value and choice, very little is known about how mindset influences these systems. In the current study, participants were primed with Health or Taste while they made decisions about snack foods. Some neural regions showed consistent associations with value and choice across Health or Taste mindsets. Regardless of mindset, medial orbitofrontal cortex (MOFC) tracked value in terms of taste, regions in left lateral prefrontal cortex (LPFC) tracked value in terms of health, and MOFC and dorsal anterior cingulate were associated with choice. However, activity in other neural regions was modulated by the mindset manipulation. When primed with Taste, rostral anterior cingulate tracked value in terms of taste whereas left amygdala and left putamen were associated with choice. When primed with Health, right LPFC and posterior MOFC tracked value in terms of health. The findings contribute to the neural research on decision-making by demonstrating that changing perspectives can modulate value- and choice-related neural activity. PMID:21972426

  2. Understanding perception and factors influencing private voluntary health insurance policy subscription in the Lucknow region

    PubMed Central

    Mathur, Tanuj; Paul, Ujjwal Kanti; Prasad, Himanshu Narayan; Das, Subodh Chandra

    2015-01-01

    Background: Health insurance has been acknowledged by researchers as a valuable tool in health financing. In spite of its significance, a subscription paralysis has been observed in India for this product. People who can afford health insurance are also found to be either ignorant or aversive towards it. This study is designed to investigate into the socio-economic factors, individuals’ health insurance product perception and individuals’ personality traits for unbundling the paradox which inhibits people from subscribing to health insurance plans. Methods: This survey was conducted in the region of Lucknow. An online questionnaire was sent to sampled respondents. Response evinced by 263 respondents was formed as a part of study for the further data analysis. For assessing the relationships between variables T-test and F-test were applied as a part of quantitative measuring tool. Finally, logistic regression technique was used to estimate the factors that influence respondents’ decision to purchase health insurance. Results: Age, dependent family members, medical expenditure, health status and individual’s product perception were found to be significantly associated with health insurance subscription in the region. Personality traits have also showed a positive relationship with respondent’s insurance status. Conclusion: We found in our study that socio-economic factors, individuals’ product perception and personality traits induces health insurance policy subscription in the region. PMID:25674567

  3. Influence of the atmospheric blocking on the hydrometeorological variables from the Danube basin and possible response to the solar/geomagnetic activity

    NASA Astrophysics Data System (ADS)

    Mares, Ileana; Dobrica, Venera; Demetrescu, Crisan; Mares, Constantin

    2015-04-01

    In order to test the large-scale atmospheric circulation influence on the hydrometeorological variables from the Danube basin, four blocking indices were considered for the regions: Greenland (GBI), Atlantic-European (AEBI), Atlantic (ABI) and Europe (EBI). In addition, an index for Greenland-Balkan Oscillation (GBOI) was introduced. For the Danube basin were analyzed: precipitation and temperatures at 15 stations and the Danube discharge at Orsova. Also, for each station were calculated four indices of Palmer type and a simple drought index (TPPI). Solar activity was represented by Wolf numbers and 10.7cm solar flux and the geomagnetic activity by the aa index. The time series of temperatures and precipitation were represented by the first principal component (PC1) of the development in empirical orthogonal functions (EOFs) and the four Palmer indices were analyzed by the PC1 of the development in multivariate EOFs (MEOFs). Cross correlations, power spectra and filters were performed. The analyses were achieved for two periods, 1901-2000 and 1948-2000, separately for each season. Concerning the simultaneous connections, for spring, the most significant results with a high confidence level (99%) were obtained for GBOI and EBI, which influence the discharge and the other hydrometeorological variables. Signals of solar or geomagnetic activity have been found only in EBI at level of 95%. For the summertime, the results are weaker. It is noted however, the significant influence of GBOI on the variables in the Danube basin, mainly on precipitation, and of EBI signal on temperatures. Solar signal is statistical significant (90% - 95%) in the GBI. Autumn, GBI, GBOI and EBI have a clear influence on all hydrometeorological fields. Signals statistically significant of aa index and 10.7 cm flux, were found in ABI and AEBI respectively. Winter, atmospheric circulation, quantified by GBI, EBI and GBOI, has an impact simultaneous on temperatures, precipitation and on the Orsova discharge. Also, significant signals of the aa index have been found in the GBI and GBOI. An analysis of the relationship between large-scale fields in the wintertime and the variables at regional / local scale during spring was achieved. This analysis revealed that the GB, GBO indices and especially EBI in wintertime are good predictors for the spring discharge. Also, the aa index in winter has a statistically significant signal (99%) in hydrometeorological variables with the highest correlation with precipitation. Also, the 10.7 cm solar flux in winter shows a statistically significant signal (at a level of 95%) in the Palmer indices as well as in temperatures and in precipitation during springtime. From the cross-correlation analysis with a lag of 5-years, between the hydroatmospheric variables and the geomagnetic or solar activity, were obtained very different results, depending on the season and variables analyzed. The most significant values have been found in summer for the 10.7 cm flux signal in variables from the Danube basin, with the 2-3 years before and after a maximum or minimum solar.

  4. The influence of low atmospheric pressure on carbon monoxide of n-heptane pool fires.

    PubMed

    Jun, Fang; Yu, Chun-Yu; Ran, Tu; Qiao, Li-Feng; Zhang, Yong-Ming; Wang, Jin-Jun

    2008-06-15

    Qualitative theoretical analysis about air pressure influence upon the gas concentration of a fire plume was given, different scale n-heptane pool fires were conducted in a small and a standard compartment room in Lhasa and Hefei, respectively. The experimental results show that, in Lhasa, the average mass burning rates in the small room and the standard room both decrease, burning time increases at about 53% in small room and 45% in standard room more than in Hefei. Whereas for maximum changes of CO concentration, in the small room, in Lhasa, CO concentrations reach about twice bigger peak values at larger increase rates than in Hefei. While in the standard room, in Lhasa and Hefei, there are no significant changes for CO concentration, which agrees well with the theoretical analysis results. PMID:18054157

  5. Regional atmospheric deposition patterns of Ag, As, Bi, Cd, Hg, Mo, Sb and Tl in a 188,000 km 2 area in the European arctic as displayed by terrestrial moss samples-long-range atmospheric transport vs local impact

    Microsoft Academic Search

    Clemens Reimann; Patrice De Caritat; Jo H. Halleraker; Tor Erik Finne; Rognvald Boyd; Øystein Jæger; Tore Volden; Galina Kashulina; Igor Bogatyrev; Viktor Chekushin; Vladimir Pavlov; Matti Äyräs; Marja Liisa Räisänen; Heikki Niskavaara

    1997-01-01

    The regional atmospheric deposition patterns of Ag, As, Bi, Cd, Hg, Mo, Sb and Tl have been mapped in a 188,000 km2 area of the European Arctic (N Finland, N Norway, NW Russia) using the moss technique. The Russian nickel mining and smelting industry (Nikel and Zapoljarnij (Pechenganikel) and Monchegorsk (Severonikel)) in the eastern part of the survey area represents

  6. Atmospheric aerosol light scattering and surface wetness influence the diurnal pattern of net ecosystem exchange in a semi-arid ponderosa pine plantation

    Microsoft Academic Search

    The diurnal variation of net ecosystem exchange (NEE) showed an unusual pattern at the Blodgett Forest Ameriflux site, with late afternoon NEE lower than early morning (indicating more uptake), while air temperature and atmospheric vapor pressure deficit were much higher. To investigate processes influencing this pattern, NEE was compared to several environmental variables during summer 2002. Unusual variations of NEE

  7. Influence of Particle Phase Morphology on the Hygroscopic Behavior of Atmospheric Aerosols

    NASA Astrophysics Data System (ADS)

    Hodas, N.; Zuend, A.; Flagan, R. C.; Seinfeld, J.

    2014-12-01

    While current models generally treat organic and mixed organic-inorganic aerosol particles as well-mixed liquids, these particles can exist in multiple phase states depending on their chemical composition and on ambient conditions such as relative humidity (RH). For example, multi-component particles can undergo phase separations in which an inorganic-electrolyte-rich phase and an organic-rich phase coexist within one particle. Organic aerosols have been shown to exist in an amorphous, highly viscous semi-solid state under atmospherically relevant conditions. Hygroscopic growth factors (GFs) of ten laboratory-generated, organic-inorganic aerosol systems with phase morphologies ranging from well-mixed liquids, to phase-separated particles, to viscous semi-solids were measured with the Differential Aerosol Sizing and Hygroscopicity Spectrometer Probe at RH values ranging from 30 - 90%. Measured GFs were compared to water-uptake calculations in which it was assumed that particles could be represented as thermodynamically ideal, well-mixed liquids, as well as those predicted by the Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model. Both ideal and AIOMFAC-predicted GFs were in good agreement with experimental GFs for aerosol systems that exist as well-mixed liquids across the range of RHs tested; however, substantial disagreement between experimental and ideal GFs was observed for phase-separated particles. This disagreement was greatest at low to moderate RHs, whereas experimental GFs approached the ideal curve at high RH as phase-separated particles merged to a single phase with increased water content. AIOMFAC, which offers the ability to predict liquid-liquid and liquid-solid phase separations within a thermodynamic equilibrium computation, was within 10% of experimental GFs at all RHs for all aerosol systems. The assumption that water uptake is driven by ideal, equilibrium partitioning leads to errors in calculated particle size and refractive index and has implications for predicted aerosol scattering efficiencies and radiative properties.

  8. Air quality resolution for health impact assessment: influence of regional characteristics

    NASA Astrophysics Data System (ADS)

    Thompson, T. M.; Saari, R. K.; Selin, N. E.

    2014-01-01

    We evaluate how regional characteristics of population and background pollution might impact the selection of optimal air quality model resolution when calculating the human health impacts of changes to air quality. Using an approach consistent with air quality policy evaluation, we use a regional chemical transport model (CAMx) and a health benefit mapping program (BenMAP) to calculate the human health impacts associated with changes in ozone and fine particulate matter resulting from an emission reduction scenario. We evaluate this same scenario at 36, 12 and 4 km resolution for nine regions in the eastern US representing varied characteristics. We find that the human health benefits associated with changes in ozone concentrations are sensitive to resolution. This finding is especially strong in urban areas where we estimate that benefits calculated using coarse resolution results are on average two times greater than benefits calculated using finer scale results. In three urban areas we analyzed, results calculated using 36 km resolution modeling fell outside the uncertainty range of results calculated using finer scale modeling. In rural areas the influence of resolution is less pronounced with only an 8% increase in the estimated health impacts when using 36 km resolution over finer scales. In contrast, health benefits associated with changes in PM2.5 concentrations were not sensitive to resolution and did not follow a pattern based on any regional characteristics evaluated. The largest difference between the health impacts estimated using 36 km modeling results and either 12 or 4 km results was at most ±10% in any region. Several regions showed increases in estimated benefits as resolution increased (opposite the impact seen with ozone modeling), while some regions showed decreases in estimated benefits as resolution increased. In both cases, the dominant contribution was from secondary PM. Additionally, we found that the health impacts calculated using several individual concentration-response functions varied by a larger amount than the impacts calculated using results modeled at different resolutions. Given that changes in PM2.5 dominate the human health impacts, and given the uncertainty associated with human health response to changes in air pollution, we conclude that, when estimating the human health benefits associated with decreases in ozone and PM2.5 together, the benefits calculated at 36 km resolution agree, within errors, with the benefits calculated using fine (12 km or finer) resolution modeling when using the current methodology for assessing policy decisions.

  9. Development of a passive doas system to retrieve atmospheric pollution columns in the 200 to 355 nm region.

    PubMed

    Mejía, Rubén Galicia; Vázquez, Josémanueldelarosa; Isakina, Suren Stolik; García, Edgard Moreno; Iglesias, Gustavo Sosa

    2013-01-01

    In recent years several techniques have been developed to measure and monitor the pollution of the air. Among these techniques, remote sensing using optical methods stands out due to several advantages for air quality control applications. A Passive Differential Optical Absorption Spectroscopy system that uses the ultraviolet region from 200 to 355 nm of the solar radiation is presented. The developed system is portable; therefore it is practical for real time and in situ measurements. The enhanced wavelength range of the system is intended to detect the ultraviolet light penetration in the Mexican Valley considering the solar zenith angle and the altitude. The system was applied to retrieve atmospheric SO2 columns emitted either by anthropogenic (power plant) or natural sources (volcano), reaching a detection limit of about 1 ppm. The measurement of the penetrating solar radiation on the earth surface at the UVC range is presented and the possibility to measure pollution traces of some contaminants as O3, NO2 and aromatic compounds in real time and in situ in the ultraviolet region is discussed. PMID:23369629

  10. Detection of deep atmospheric disintegration of a large meteoroid over the northern Adriatic region by a seismic network on July 25, 2007

    NASA Astrophysics Data System (ADS)

    Atanackov, J.; Kac, J.; Kladnik, G.

    2009-04-01

    An atmospheric disintegration of a large meteoroid over the northern Adriatic region was observed by numerous witnesses and detected by seismographs of the Environmental Agency of Slovenia on July 25, 2007. Analysis of seismic records produced an approximate atmospheric trajectory of the body, its fragmentation sequence and an estimate of the energy released during individual fragmentation events. Seismographs show evidence of two major fragmentation events, confirmed also by eyewitness reports and dust train morphology. Ray tracing analysis of sound wave propagation on an atmosphere model based on regional sounding data show the acoustic signature to be composed of a sequence of point source signatures corresponding to individual fragmentation events, rather than a line source produced by ballistic passage of the meteoroid through the atmosphere. The two major fragmentation events occurred in the vicinity of Jablan village in northwestern Croatia at altitudes of 22 and 30 km. Several minor fragmentation events were also identified as well as a continuous background signal, which suggests near-continuous fragmentation of the meteoroid during its atmospheric passage starting at 38 km and possibly as high as 49 km. Using empiric relationships for determination of explosive blast yield for ground-coupled atmospheric shockwaves derived from surface and near-surface high-explosive blasts, adapted for high altitude detonations, the released energy by the meteoroid was estimated at 3 x 1012 J, equivalent to ~0.7 kt TNT. While seismic records inherently produce estimates accurate only to within an order of magnitude, this is in good agreement with the upper limit constrained using acoustic detections of the detonations by the most distant eyewitnesses. The deep atmospheric penetration implies a strong rocky, rather than a cometary meteoroid, on the order of several meters across. The derived atmospheric trajectory permits determination of the meteor's radiant. Assuming origin in the main asteroid belt, the pre-atmospheric orbit was determined as an Apollo-type orbit with perihelion distance q>0.81 a.u. and aphelion

  11. How Processing Atmosphere Influences the Evolution of GeO[subscript 2]-Embedded Germanium Nanocrystals Obtained from the Thermolysis of Phenyl Trichlorogermane-Derived Polymers

    SciTech Connect

    Henderson, Eric J.; Hessel, Colin M.; Cavell, Ronald G.; Veinot, Jonathan G.C. (Alberta)

    2010-06-22

    We report the influence of processing atmosphere on the evolution of oxide-embedded germanium nanocrystals (Ge-NCs) formed by the thermal processing of (C{sub 6}H{sub 5}GeO{sub 1.5}){sub n} sol-gel polymers. In an inert processing atmosphere (100% Ar), the generation of elemental Ge from thermally induced disproportionation of the germanium rich oxide (GRO) leads to GeO{sub 2}-embedded Ge-NCs whose size is independent of peak processing temperature and time. Processing in a slightly reducing atmosphere (5% H{sub 2}/95% Ar) activates a second Ge-NC formation and growth pathway, involving the reduction of Ge oxide species. Here, we report that the processing atmosphere governs the distribution of Ge species. By modifying the contributions from redistribution and reduction reactions within the GRO, diffusion of Ge atoms throughout the oxide matrix and formation and growth of Ge-NCs are impacted.

  12. Long-term changes and trends in total ozone over the northern mid-latitudes: Influence of atmospheric dynamics and chemistry and contribution from extreme events

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    Downward trends in global stratospheric ozone during recent decades have been shown to be directly linked to increasing surface UV-radiation. In the past, long-term ozone trends were determined from homogenized data series by fitting with multiple linear regression models, in which suitable independent variables (so-called explanatory variables) were used to represent atmospheric variability, such as the Quasi-Biennial Oscillation (QBO), the 11-year solar cycle, and a linear trend attributed to anthropogenic ozone depletion. Previous studies have identified a number of other processes influencing total ozone at mid-latitudes, such as synoptic-scale meteorological variability, decadal or long-term climate variability, described e.g. by the Northern Atlantic Oscillation (NAO), the Arctic Oscillation (AO), atmospheric circulation indices ENSO, temperature at the 470-K isentrope level, and volcanic eruptions. Due to the successful implementation of the Montreal Protocol the discussion about a recovery or possible “super recovery” started within the scientific community. Here we address long-term changes and trends in a different framework. As statistical analysis showed that previously used concepts assuming a Gaussian distribution of total ozone data do not address the internal data structure concerning extremes adequately methods from extreme value theory are applied on local (various long-term ground based total ozone records) and regional (high resolution homogenized satellite data) scale. Within the extreme value theory framework days with extreme low (ELOs) and high (EHOs) total ozone are analyzed and their frequency is linked to changes in atmospheric chemistry and dynamics. The results show: (i) an increase in ELOs and (ii) a decrease in EHOs during the last decades and (iii) that the overall trend during the 1970s and 1980s in total ozone is strongly dominated by changes in these extreme events. After removing the extremes, the different time series show a strongly reduced trend (reduction by about a factor of 2 (or more)). Excursions in the frequency of extreme events reveal “fingerprints” of dynamical factors such as ENSO or NAO, and chemical factors, such as cold Arctic vortex ozone losses, as well as major volcanic eruptions of the 20th century (Gunung Agung, El Chichón, Mt. Pinatubo). Furthermore, atmospheric loading of ozone depleting substances leads to a continuous modification of column ozone in the northern hemisphere also with respect to extreme values (partly again in connection with polar vortex contributions). The results reveal that application of extreme value theory allows the identification of many more such “fingerprints” than conventional time series analysis of annual and seasonal mean values. Overall the approach to extremal modelling provides new information on time series properties, variability, trends and the influence of dynamics and chemistry, complementing earlier analyses focusing only on monthly (or annual) mean values.

  13. Influence of modified atmosphere and varying time in storage on the irradiation sensitivity of Salmonella on sliced roma tomatoes

    NASA Astrophysics Data System (ADS)

    Niemira, Brendan A.; Boyd, Glenn

    2013-09-01

    Salmonella contamination of tomatoes is a recurrent food safety concern. Irradiation inactivates pathogens on fresh and fresh cut produce. However, the interaction of time in refrigerated storage and modified atmosphere packaging (MAP) may influence the response of pathogens to irradiation. Roma tomatoes were sliced and inoculated with a cocktail of outbreak strains of Salmonella. The inoculated tomatoes were packaged under one of four atmospheres: air, 10/90 O2/N2, 5/95 O2/N2 or 100% N2. The packages were kept in refrigerated storage (10 °C) for various times after inoculation, to simulate the potential time delay between packaging and irradiation treatment. Tomatoes were irradiated immediately (0 h), or after 24 or 48 h in storage. The surviving populations were recovered and enumerated. Irradiation effectively reduced Salmonella at all times. Estimated D10 value (the dose necessary for 1 log reduction) varied significantly among the combinations of time and MAP, ranging from 0.165-0.335 kGy. Tomatoes packaged in air, irradiated at 0 h, had a D10 of 0.165 kGy; all other combinations showed significantly higher D10. Reduced oxygen generally resulted in higher D10 values, with the highest D10 of 0.335 kGy obtained for 100% N2, 0 h. Time in storage pre-irradiation tended to increase D10 for air and 5/95 O2/N2, but not for 10/90 O2/N2 or 100% N2. These results suggest that time required for refrigerated holding of processed Roma tomatoes or shipment to an off-site irradiation service provider may alter the efficacy of irradiation if reduced oxygen MAP is used.

  14. Atmospheric pressure plasma jet treatment evokes transient oxidative stress in HaCaT keratinocytes and influences cell physiology.

    PubMed

    Wende, Kristian; Straßenburg, Susanne; Haertel, Beate; Harms, Manuela; Holtz, Sarah; Barton, Annemarie; Masur, Kai; von Woedtke, Thomas; Lindequist, Ulrike

    2014-04-01

    Modern non-thermal atmospheric pressure plasma sources enable controllable interaction with biological systems. Their future applications - e.g. wound management - are based on their unique mixture of reactive components sparking both stimulatory as well as inhibitory processes. To gain detailed understanding of plasma-cell interaction and with respect to risk awareness, key mechanisms need to be identified. This study focuses on the impact of an argon non-thermal atmospheric pressure plasma jet (kINPen 09) on human HaCaT keratinocytes. With increasing duration, cell viability decreased. In accordance, cells accumulated in G2/M phase within the following 24?h. DNA single-strand breaks were detected immediately after treatment and receded in the aftermath, returning to control levels after 24?h. No directly plasma-related DNA double-strand breaks were detected over the same time. Concurrently, DNA synthesis decreased. Coincident with treatment time, an increase in intracellular 2',7'-dichlorodihydrofluorescein diacetate (H(2)DCFDA) conversion increased reactive oxygen species (ROS) levels. The radical scavenging activity of culture medium crucially influenced these effects. Thus, ROS changed DNA integrity, and the effectiveness of cellular defence mechanisms characterises the interaction of non-thermal plasma and eukaryotic cells. Effects were time-dependent, indicating an active response of the eukaryotic cells. Hence, a stimulation of eukaryotic cells using short-term non-thermal plasma treatment seems possible, eg in the context of chronic wound care. Long-term plasma treatments stopped in cell proliferation and apoptosis, which might be relevant in controlling neoplastic conditions. PMID:24155089

  15. Influence of air-jet vortex generator diameter on separation region

    NASA Astrophysics Data System (ADS)

    Szwaba, Ryszard

    2013-08-01

    Control of shock wave and boundary layer interaction continues to attract a lot of attention. In recent decades several methods of interaction control have been investigated. The research has mostly concerned solid (vane type) vortex generators and transpiration methods of suction and blowing. This investigation concerns interaction control using air-jets to generate streamwise vortices. The effectiveness of air-jet vortex generators in controlling separation has been proved in a previous research. The present paper focuses on the influence of the vortex generator diameter on the separation region. It presents the results of experimental investigations and provides new guidelines for the design of air-jet vortex generators to obtain more effective separation control.

  16. Atmosphere influence on in situ ion beam analysis of thin film growth

    SciTech Connect

    Lin, Yuping [Argonne National Lab., IL (United States)]|[Northwestern Univ., Evanston, IL (United States); Krauss, A.R.; Gruen, D.M. [Argonne National Lab., IL (United States); Chang, R.P.H. [Northwestern Univ., Evanston, IL (United States); Auciello, O.H. [MCNC, Research Triangle Park, NC (United States); Schultz, J.A. [Ionwerks, Inc., Houston, TX (United States)

    1994-10-01

    In situ, nondestructive surface characterization of thin-film growth processes in an environment of chemically active gas at pressures of several mTorr is required both for the understanding of growth processes in multicomponent films and layered heterostructures and for the improvement of process reproducibility and device reliability. The authors have developed a differentially pumped pulsed ion beam surface analysis system that includes ion scattering spectroscopy (ISS) and direct recoil spectroscopy (DRS), coupled to an automated ion beam sputter-deposition system (IBSD), to study film growth processes in an environment of chemically active gas, such as required for the growth of oxide, nitride, or diamond thin films. The influence of gas-phase scattering and gas-surface interactions on the ISS and DRS signal intensity and peak shape have been studied. From the intensity variation as a function of ambient gas pressure, the authors have calculated the mean free path and the scattering cross-section for a given combination of primary ion species and ambient gas. Depending on the system geometry and the combination of primary beam and background, it is shown that surface-specific data can be obtained during thin-film growth at pressures ranging from a few mtorr to approximately 1 Torr. Detailed information such as surface composition, structure, and film growth mechanism may be obtained in real-time, making ion beam analysis an ideal nondestructive, in situ probe of thin-film growth processes.

  17. CO2 flux estimation accuracy evaluation of Global and Regional atmospheric CO2 mission concepts

    NASA Astrophysics Data System (ADS)

    Lee, M.; Miller, C.; Weidner, R. J.; Duren, R. M.; Sander, S.; Eldering, A.

    2012-12-01

    We developed an observing system simulation experiment (OSSE) framework to evaluate mission-science-return quantitatively as a function of instrument payload, observation frequency, orbit, and sampling strategy for space-based remote sensing. The OSSE framework integrates GEOSChem and its adjoint system to perform forward/inverse modeling of the simulated measurements. During 2011-2012, we extended the OSSE framework to evaluate CO2 mission concepts in collaboration with the NASA's carbon monitoring system (CMS) flux pilot project team. In this paper, we employ the OSSE framework to analyze the science impact of multiple, simultaneous space-based column CO2 observations from simulated combinations of GOSAT, OCO-2, OCO-3, and a geo-stationary mission concept (GEOFTS). The OSSE process involved generating a CO2 concentration forecast, sampling the CO2 field at the appropriate time and location for each satellite sensor, incorporating realistic cloud climatologies to generate accurate clear-sky viewing statistics, retrieving CO2 profile simulaton in the presence of measurement noise, and finally assimilating the simulated column CO2 retrievals to estimate CO2 fluxes and flux uncertainty reductions. The OSSE process was applied over one-year-long mission period (2009/Jan - 2009/Dec) and the CO2 flux estimation error was analyzed to compute the probability density function (PDF) of CO2 flux estimation-error-reduction. The global OSSEs were performed in 2deg x 2.5 deg spatial resolution with the monthly-average CO2 flux estimation-error-reduction as the science-impact metric. Regional OSSEs were performed in 0.5 deg by 0.666 deg over N. America and the weekly average of the CO2 flux estimation-error-reduction was employed as the science-impact metric. We discuss the results and the projected performance of planned and potential space-based CO2 observing systems.

  18. Pluto's atmosphere

    Microsoft Academic Search

    J. L. Elliot; E. W. Dunham; A. S. Bosh; S. M. Slivan; L. A. Young

    1989-01-01

    Airborne CCD photometer observations of Pluto's June 9, 1988 stellar occultation have yielded an occultation lightcurve, probing two regions on the sunrise limb 2000 km apart, which reveals an upper atmosphere overlying an extinction layer with an abrupt upper boundary. The extinction layer may surround the entire planet. Attention is given to a model atmosphere whose occultation lightcurve closely duplicates

  19. The Barcelona Dust Forecast Center: The first WMO regional meteorological center specialized on atmospheric sand and dust forecast

    NASA Astrophysics Data System (ADS)

    Basart, Sara; Terradellas, Enric; Cuevas, Emilio; Jorba, Oriol; Benincasa, Francesco; Baldasano, Jose M.

    2015-04-01

    The World Meteorological Organization's Sand and Dust Storm Warning Advisory and Assessment System (WMO SDS-WAS, http://sds-was.aemet.es/) project has the mission to enhance the ability of countries to deliver timely and quality sand and dust storm forecasts, observations, information and knowledge to users through an international partnership of research and operational communities. The good results obtained by the SDS-WAS Northern Africa, Middle East and Europe (NAMEE) Regional Center and the demand of many national meteorological services led to the deployment of operational dust forecast services. On June 2014, the first WMO Regional Meteorological Center Specialized on Atmospheric Sand and Dust Forecast, the Barcelona Dust Forecast Center (BDFC; http://dust.aemet.es/), was publicly presented. The Center operationally generates and distributes predictions for the NAMEE region. The dust forecasts are based on the NMMB/BSC-Dust model developed at the Barcelona Supercomputing Center (BSC-CNS). The present contribution will describe the main objectives and capabilities of BDFC. One of the activities performed by the BDFC is to establish a protocol to routinely exchange products from dust forecast models as dust load, dust optical depth (AOD), surface concentration, surface extinction and deposition. An important step in dust forecasting is the evaluation of the results that have been generated. This process consists of the comparison of the model results with multiple kinds of observations (i.e. AERONET and MODIS) and is aimed to facilitate the understanding of the model capabilities, limitations, and appropriateness for the purpose for which it was designed. The aim of this work is to present different evaluation approaches and to test the use of different observational products in the evaluation system.

  20. In situ measurements of speciated atmospheric mercury and the identification of source regions in the Mexico City Metropolitan Area

    E-print Network

    Rutter, A. P.

    In order to expand the currently limited understanding of atmospheric mercury source-receptor relationships in the Mexico City Metropolitan Area, real time measurements of atmospheric mercury were made at a downtown urban ...

  1. The influence of solar wind on extratropical cyclones - Part 2: A link mediated by auroral atmospheric gravity waves?

    NASA Astrophysics Data System (ADS)

    Prikryl, P.; Muldrew, D. B.; Sofko, G. J.

    2009-01-01

    Cases of mesoscale cloud bands in extratropical cyclones are observed a few hours after atmospheric gravity waves (AGWs) are launched from the auroral ionosphere. It is suggested that the solar-wind-generated auroral AGWs contribute to processes that release instabilities and initiate slantwise convection thus leading to cloud bands and growth of extratropical cyclones. Also, if the AGWs are ducted to low latitudes, they could influence the development of tropical cyclones. The gravity-wave-induced vertical lift may modulate the slantwise convection by releasing the moist symmetric instability at near-threshold conditions in the warm frontal zone of extratropical cyclones. Latent heat release associated with the mesoscale slantwise convection has been linked to explosive cyclogenesis and severe weather. The circumstantial and statistical evidence of the solar wind influence on extratropical cyclones is further supported by a statistical analysis of high-level clouds (<440 mb) extracted from the International Satellite Cloud Climatology Project (ISCCP) D1 dataset. A statistically significant response of the high-level cloud area index (HCAI) to fast solar wind from coronal holes is found in mid-to-high latitudes during autumn-winter and in low latitudes during spring-summer. In the extratropics, this response of the HCAI to solar wind forcing is consistent with the effect on tropospheric vorticity found by Wilcox et al. (1974) and verified by Prikryl et al. (2009). In the tropics, the observed HCAI response, namely a decrease in HCAI at the arrival of solar wind stream followed by an increase a few days later, is similar to that in the northern and southern mid-to-high latitudes. The amplitude of the response nearly doubles for stream interfaces associated with the interplanetary magnetic field BZ component shifting southward. When the IMF BZ after the stream interface shifts northward, the autumn-winter effect weakens or shifts to lower (mid) latitudes and no statistically significant response is found at low latitudes in spring-summer. The observed effect persists through years of low and high volcanic aerosol loading. The similarity of the response in mid-to-high and low latitudes, the lack of dependence upon aerosol loading, and the enhanced amplitude of the effect when IMF BZ component shifts southward, favor the proposed AGW link over the atmospheric electric circuit (AEC) mechanism (Tinsley et al., 1994). The latter requires the presence of stratospheric aerosols for a significant effect and should produce negative and positive cloud anomalies in mid-to-high and low latitudes, respectively. However, if the requirement of aerosols for the AEC mechanism can be relaxed, the AGW and AEC mechanisms should work in synergy at least in mid-to-high latitudes.

  2. LIDAR vertical profiles over the Oil Sands Region: an important tool in understanding atmospheric particulate matter transport, mixing and transformation

    NASA Astrophysics Data System (ADS)

    Strawbridge, K. B.

    2013-12-01

    LIDAR technology is an excellent tool to probe the complex vertical structure of the atmosphere at high spatial and temporal resolution. This provides the critical vertical context for the interpretation of ground-based chemistry measurements, airborne measurements and model verification and validation. In recent years, Environment Canada has designed an autonomous aerosol LIDAR system that can be deployed to remote areas such as the oil sands. Currently two autonomous LIDAR systems are making measurements in the oil sands region, one since December, 2012 and the other since July, 2013. The LIDAR transmitter emits two wavelengths (1064nm and 532nm) and the detector assembly collects four channels (1064nm backscatter, 532nm backscatter and 532nm depolarization, 607 nm nitrogen channel). Aerosol profiles from near ground to 20 km are collected every 10-60 s providing sufficient resolution to probe atmospheric dynamics, mixing and transport. The depolarization channel provides key information in identifying and discriminating the various aerosol layers aloft such as dust, forest fire plumes, industrial plume sources or ice crystals. The vertical resolution of the LIDAR can determine whether industrial plumes remain aloft or mix down to the surface and also provide estimates as to the concentration of the particulate at various altitudes. It operates 24 hours a day, seven days a week except during precipitation events. The system is operated remotely and the data are updated every hour to a website to allow near real-time capability. An intensive measurement campaign will be carried out in August and September of 2013 and will provide coincident airborne and ground-based measurements for the two LIDAR systems. The first results from this field study will be presented as well as some statistics on the frequency and evolution of plume events that were detected by the LIDARs.

  3. Does regional compared to local anaesthesia influence outcome after arteriovenous fistula creation?

    PubMed Central

    2013-01-01

    Background An arteriovenous fistula is the optimal form of vascular access in patients with end-stage renal failure requiring haemodialysis. Unfortunately, approximately one-third of fistulae fail at an early stage. Different anaesthetic techniques can influence factors associated with fistula success, such as intraoperative blood flow and venous diameter. A regional anaesthetic brachial plexus block results in vasodilatation and improved short- and long-term fistula flow compared to the infiltration of local anaesthetic alone. This, however, has not yet been shown in a large trial to influence long-term fistula patency, the ultimate clinical measure of success. The aim of this study is to compare whether a regional anaesthetic block, compared to local anaesthetic infiltration, can improve long-term fistula patency. Methods This study is an observer-blinded, randomised controlled trial. Patients scheduled to undergo creation of either brachial or radial arteriovenous fistulae will receive a study information sheet, and consent will be obtained in keeping with the Declaration of Helsinki. Patients will be randomised to receive either: (i) an ultrasound guided brachial plexus block using lignocaine with adrenaline and levobupivicaine, or (ii) local anaesthetic infiltration with lignocaine and levobupivicaine. A total of 126 patients will be recruited. The primary outcome is fistula primary patency at three months. Secondary outcomes include primary patency at 1 and 12 months, secondary patency and fistula flow at 1, 3 and 12 months, flow on first haemodialysis, procedural pain, patient satisfaction, change in cephalic vein diameter pre- and post-anaesthetic, change in radial or brachial artery flow pre- and post-anaesthetic, alteration of the surgical plan after anaesthesia as guided by vascular mapping with ultrasound, and fistula infection requiring antibiotics. Conclusions No large randomised controlled trial has examined the influence of brachial plexus block compared with local anaesthetic infiltration on the long-term patency of arteriovenous fistulae. If the performance of brachial plexus block increases fistulae patency, this will have significant clinical and financial benefits as the number of patients able to commence haemodialysis when planned should increase, and the number of “redo” or revision procedures should be reduced. Trial registration This study has been approved by the West of Scotland Research Ethics Committee 5 (reference no. 12/WS/0199) and is registered with the ClinicalTrials.gov database (reference no. NCT01706354). PMID:23958289

  4. The length of a lantibiotic hinge region has profound influence on antimicrobial activity and host specificity

    PubMed Central

    Zhou, Liang; van Heel, Auke J.; Kuipers, Oscar P.

    2015-01-01

    Lantibiotics are ribosomally synthesized (methyl)lanthionine containing peptides which can efficiently inhibit the growth of Gram-positive bacteria. As lantibiotics kill bacteria efficiently and resistance to them is difficult to be obtained, they have the potential to be used in many applications, e.g., in pharmaceutical industry or food industry. Nisin can inhibit the growth of Gram-positive bacteria by binding to lipid II and by making pores in their membrane. The C-terminal part of nisin is known to play an important role during translocation over the membrane and forming pore complexes. However, as the thickness of bacterial membranes varies between different species and environmental conditions, this property could have an influence on the pore forming activity of nisin. To investigate this, the so-called “hinge region” of nisin (residues NMK) was engineered to vary from one to six amino acid residues and specific activity against different indicators was compared. Antimicrobial activity in liquid culture assays showed that wild type nisin is most active, while truncation of the hinge region dramatically reduced the activity of the peptide. However, one or two amino acids extensions showed only slightly reduced activity against most indicator strains. Notably, some variants (+2, +1, ?1, ?2) exhibited higher antimicrobial activity than nisin in agar well diffusion assays against Lactococcus lactis MG1363, Listeria monocytogenes, Enterococcus faecalis VE14089, Bacillus sporothermodurans IC4 and Bacillus cereus 4153 at certain temperatures. PMID:25688235

  5. The correction of infrasound signals for upper atmospheric winds

    SciTech Connect

    Mutschlecner, J.P.; Whitaker, R.W.

    1990-01-01

    Infrasound waves propagate in the atmosphere by a well known mechanism produced by refraction of the waves, return to earth, and reflection at the surface into the atmosphere for subsequent bounces. In this instance three rays are returned to earth from a region centered at about 50 kilometers in altitude and two from a region near 110 kilometers in altitude. The control of the wave refraction is largely dominated by the temperature-height profile and inversions; however, a major influence is also produced by the atmospheric wind profile. It obviously can be expected that infrasonic signal amplitudes will be greatly influenced by the winds in the atmosphere. The seasonal variation of the high altitude atmospheric winds is well documented. The very strong seasonal variation has the ability to exert a major seasonal influence on infrasonic signals. It is our purpose to obtain a method for the correction of this effect.

  6. The influence of ozone on atmospheric emissions of gaseous elemental mercury and reactive gaseous mercury from substrates

    USGS Publications Warehouse

    Engle, M.A.; Sexauer, Gustin M.; Lindberg, S.E.; Gertler, A.W.; Ariya, P.A.

    2005-01-01

    Experiments were performed to investigate the effect of ozone (O 3) on mercury (Hg) emission from a variety of Hg-bearing substrates. Substrates with Hg(II) as the dominant Hg phase exhibited a 1.7 to 51-fold increase in elemental Hg (Hgo) flux and a 1.3 to 8.6-fold increase in reactive gaseous mercury (RGM) flux in the presence of O3-enriched clean (50 ppb O3; 8 substrates) and ambient air (up to ???70 ppb O3; 6 substrates), relative to clean air (oxidant and Hg free air). In contrast, Hgo fluxes from two artificially Hgo-amended substrates decreased by more than 75% during exposure to O3-enriched clean air relative to clean air. Reactive gaseous mercury emissions from Hg o-amended substrates increased immediately after exposure to O 3 but then decreased rapidly. These experimental results demonstrate that O3 is very important in controlling Hg emissions from substrates. The chemical mechanisms that produced these trends are not known but potentially involve heterogenous reactions between O3, the substrate, and Hg. Our experiments suggest they are not homogenous gas-phase reactions. Comparison of the influence of O3 versus light on increasing Hgo emissions from dry Hg(II)-bearing substrates demonstrated that they have a similar amount of influence although O3 appeared to be slightly more dominant. Experiments using water-saturated substrates showed that the presence of high-substrate moisture content minimizes reactions between atmospheric O3 and substrate-bound Hg. Using conservative calculations developed in this paper, we conclude that because O3 concentrations have roughly doubled in the last 100 years, this could have increased Hgo emissions from terrestrial substrates by 65-72%. ?? 2005 Elsevier Ltd. All rights reserved.

  7. Contrasting Indian Ocean SST Variability With and Without ENSO Influence: A Coupled Atmosphere-Ocean GCM Study

    NASA Technical Reports Server (NTRS)

    Yu, Jin-Yi; Lau, K. M.

    2004-01-01

    In this study, we perform experiments with a coupled atmosphere-ocean general circulation model (CGCM) to examine ENSO's influence on the interannual sea surface temperature (SST) variability of the tropical Indian Ocean. The control experiment includes both the Indian and Pacific Oceans in the ocean model component of the CGCM (the Indo-Pacific Run). The anomaly experiment excludes ENSOs influence by including only the Indian Ocean while prescribing monthly-varying climatological SSTs for the Pacific Ocean (the Indian-Ocean Run). In the Indo-Pacific Run, an oscillatory mode of the Indian Ocean SST variability is identified by a multi-channel singular spectral analysis (MSSA). The oscillatory mode comprises two patterns that can be identified with the Indian Ocean Zonal Mode (IOZM) and a basin-wide warming/cooling mode respectively. In the model, the IOZM peaks about 3-5 months after ENSO reaches its maximum intensity. The basin mode peaks 8 months after the IOZM. The timing and associated SST patterns suggests that the IOZM is related to ENSO, and the basin- wide warming/cooling develops as a result of the decay of the IOZM spreading SST anomalies from western Indian Ocean to the eastern Indian Ocean. In contrast, in the Indian-Ocean Run, no oscillatory modes can be identified by the MSSA, even though the Indian Ocean SST variability is characterized by east-west SST contrast patterns similar to the IOZM. In both control and anomaly runs, IOZM-like SST variability appears to be associated with forcings from fluctuations of the Indian monsoon. Our modeling results suggest that the oscillatory feature of the IOZM is primarily forced by ENSO.

  8. The influence of the atmospheric boundary layer on nocturnal layers of noctuids and other moths migrating over southern Britain

    NASA Astrophysics Data System (ADS)

    Wood, Curtis R.; Chapman, Jason W.; Reynolds, Donald R.; Barlow, Janet F.; Smith, Alan D.; Woiwod, Ian P.

    2006-03-01

    Insects migrating at high altitude over southern Britain have been continuously monitored by automatically operating, vertical-looking radars over a period of several years. During some occasions in the summer months, the migrants were observed to form well-defined layer concentrations, typically at heights of 200-400 m, in the stable night-time atmosphere. Under these conditions, insects are likely to have control over their vertical movements and are selecting flight heights that are favourable for long-range migration. We therefore investigated the factors influencing the formation of these insect layers by comparing radar measurements of the vertical distribution of insect density with meteorological profiles generated by the UK Meteorological Office’s (UKMO) Unified Model (UM). Radar-derived measurements of mass and displacement speed, along with data from Rothamsted Insect Survey light traps, provided information on the identity of the migrants. We present here three case studies where noctuid and pyralid moths contributed substantially to the observed layers. The major meteorological factors influencing the layer concentrations appeared to be: (a) the altitude of the warmest air, (b) heights corresponding to temperature preferences or thresholds for sustained migration and, (c) on nights when air temperatures are relatively high, wind-speed maxima associated with the nocturnal jet. Back-trajectories indicated that layer duration may have been determined by the distance to the coast. Overall, the unique combination of meteorological data from the UM and insect data from entomological radar described here show considerable promise for systematic studies of high-altitude insect layering.

  9. A comparison between shell-based ?13C values from an extratropical setting (Gulf of Maine, USA) and atmospheric ?13C values for intervals of the last millennium: insights on regional hydrography and carbon dynamics

    NASA Astrophysics Data System (ADS)

    Wanamaker, A. D.; Kreutz, K. J.; Introne, D.; Beirne, E. C.

    2010-12-01

    To explore past changes in carbon dynamics in the Gulf of Maine, and to further evaluate the utility of stable carbon isotope ratios (?13C) derived from the aragonitic shells of the marine bivalve Arctica islandica in global change studies, we compared annual shell ?13C values (N = 4; total of 333 years) with published atmospheric ?13C data (derived from ice cores [AD 1006 to AD 1978; N = 58 measurements] and instrumental series (AD 1981 to AD 2008; total of 28 years]) for intervals of the last millennium. Both datasets were modeled using an exponential function to highlight the low frequency trends in the data and to facilitate a relevant comparison. From AD 1000 to AD 1800, the modeled atmospheric ?13C series increased by 0.20 ‰ (change = 0.00025 ‰ per year), while modeled shell ?13C series decreased by 0.24 ‰ (change = -0.00030 ‰ per year). From AD 1800 to present, both modeled ?13C datasets decreased substantially due to the admixture of isotopically negative carbon derived from increased fossil fuel emissions. The magnitude of the change during this interval in the atmospheric pool was 2.0 ‰ (rate = - 0.0095 ‰ per year), whereas the change in the shell-based values was 1.1 ‰ (rate = - 0.0052 ‰ per year), approximately half of the change noted in the atmosphere. Remarkably, the rate of change in shell ?13C values during the last 200 years was 17 times faster than the previous 800 years. Although the long-term offset (range 8.9 - 8.5 ‰) between atmospheric and shell ?13C data was not constant from AD 1000 to AD 1800, the converging nature of the modeled data suggest that regional hydrographic conditions within the Gulf of Maine during the last millennium have also influenced the ?13C signature in the shells. We will explore some possible hydrographic mechanisms that might explain the divergence between atmospheric and shell-based ?13C values. Despite the noted difference in the atmospheric and shell-based ?13C records, it appears that the ?13C signal derived from A. islandica may be a suitable proxy to investigate carbon dynamics at the regional scale. However, additional work (i.e., robust calibrations) is required before this proxy can be used to quantitatively reconstruct past marine dissolved inorganic carbon (?13CDIC).

  10. Influence of SST from Pacific and Atlantic Ocean and atmospheric circulation in the precipitation regime of basin from Brazilian SIN

    NASA Astrophysics Data System (ADS)

    Custodio, M. D.; Ramos, C. G.; Madeira, P.; de Macedo, A. L.

    2013-12-01

    The South American climate presents tropical, subtropical and extratropical features because of its territorial extension, being influenced by a variety of dynamical systems with different spatial and temporal scales which result in different climatic regimes in their subregions. Furthermore, the precipitation regime in South America is influenced by low-frequency phenomena as El Niño-Southern Oscillation (ENSO), the Atlantic dipole and the Madden Julian Oscilation (MJO), in other words, is directly influenced by variations of the Sea Surface Temperature (SST). Due to the importance of the precipitation for many sectors including the planning of productive activities, such as agriculture, livestock and hydropower energy, many studies about climate variations in Brazil have tried to determine and explain the mechanisms that affect the precipitation regime. However, because of complexity of the climate system, and consequently of their impacts on the global precipitation regime, its interactions are not totally understood and therefore misrepresented in numerical models used to forecast climate. The precipitation pattern over hydrographic basin which form the Brasilian National Interconnected System (Sistema Interligado Nacional-SIN) are not yet known and therefore the climate forecast of these regions still presents considerable failure that need to be corrected due to its economic importance. In this context, the purpose here is to determine the precipitation patterns on the Brazilian SIN, based on SST and circulation observed data. In a second phase a forecast climate model for these regions will be produced. In this first moment 30 years (1983 to 2012) of SST over Pacific and Atlantic Ocean were analyzed, along with wind in 850 and 200 hPa and precipitation observed data. The precipitation patterns were analyzed through statistical analyses for interannual (ENSO) and intraseasonal (MJO) anomalies for these variables over the SIN basin. Subsequently, these precipitation patterns will be used for the development of a statistical model for climate prediction for each of these regions, with which it is expected an improvement of up to 20% of climate prediction in these basins. In this first stage was evident a high correlation between precipitation in the basins of SIN and SST Pacific anomalies over the region of Niños, as well as on the coast of Chile and Peru. The effect of SST anomalies in the Niños region on precipitation in the South America is already known, however its quantification was not yet well understood. The coast of Chile determines the positioning and movement of cold fronts directly affecting rainfall in southern and southeastern of Brazil, then the correlation and rain pattern indicate the parameters for the climate prediction model. The anomalies over the Atlantic ocean present high correlation with the precipitation in North and Northeast of Brazil, as well as its connection with the Pacific anomalies. This quantification generated climatic parameters for predictions for these regions. The relationship between the canonical ENSO events and precipitation regime on the basins were also quantified which represents a high degree of assertiveness in predicting climate of these regions.

  11. Volatile organic compound distributions during the NACHTT campaign at the Boulder Atmospheric Observatory: Influence of urban and natural gas sources

    NASA Astrophysics Data System (ADS)

    Swarthout, Robert F.; Russo, Rachel S.; Zhou, Yong; Hart, Andrew H.; Sive, Barkley C.

    2013-09-01

    comprehensive suite of volatile organic compounds (VOCs) was measured at the semirural Boulder Atmospheric Observatory (BAO) in northeast Colorado during the Nitrogen, Aerosol Composition, and Halogens on a Tall Tower (NACHTT) campaign during the winter of 2011. A signature of elevated nonmethane hydrocarbon (NMHC) mixing ratios was observed throughout the campaign. The C2-C5 alkane mixing ratios were an order of magnitude greater than the regional background. Light alkane mixing ratios were similar to those at urban sites impacted by petrochemical industry emissions with ethane and propane reaching maximums of over 100 ppbv. The mean (± standard deviation) calculated total OH reactivity (7.0 ± 5.0 s-1) was also similar to urban sites. Analysis of VOC wind direction dependence, emission ratios with tracer compounds, and vertical profiles up to 250 m implicated regional natural gas production activities as the source of the elevated VOCs to the northeast of BAO and urban combustion emissions as the major VOC source to the south of BAO. Elevated acetonitrile and dimethyl sulfide mixing ratios were also associated with natural gas emissions. Fluxes of natural gas associated NMHCs were determined to estimate regional emission rates which ranged from 40 ± 14 Gg yr-1 for propane to 0.03 ± 0.01 Gg yr-1 for n-nonane. These emissions have the potential to impact downwind air quality as natural gas associated NMHCs comprised ?24% of the calculated OH reactivity. The measurements described here provide a baseline for determining the efficacy of future policies designed to control emissions from natural gas production activities.

  12. Mass Motions Under the Influence of the Magnetic Field in Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Georgakilas, A. A.

    1992-03-01

    We have studied the development of active region arch structures in H? and mass motions associated with them. Our emphasis was on the spatial structure and the temporal evolution of the velocity. We reconstructed the velocity vector along the arch filaments and computed models for the material flow. A large developing active region (Mc Math No 16315) was observed for six days from September 25 to September 30 1979. The observations were obtained with a Halle H? filter (0.5 Passband) mounted on the 50 cm "Tourelle" refractor of the Pic-du-Midi Observatory. On the first day of our observations the active region consisted of only two well developed spots, while on the sixth day it had many large spots and its structure was quite complex. We also used observations of an arch filament system (AFS) in NOAA region 4819 made on June 22, 1987 covering a time interval of 15 m 27 sec. These observations were obtained with the Multichannel Double Pass Spectograph (MSDP) mounted on the 50 cm "Tourelle" refractor of the Pic-du-Midi observatory. The MSDP provides 10 simultaneous intensity images of the same region, 0.256 Angstrem apart in the H? line. We developed a method for the computation of the line-of-sight velocity from photographs at H?+- 0.5 Angstrem, under the assumption of Becker's cloud model and resonable assumptions about the Doppler width and optical depth of the arches. For the MSDP data we reconstructed line profiles and monochromatic images and we measured Doppler velocities. Furthemore, using Becker's cloud model, we derived physical parameters and in particular the line of sight velocity. from the line of sight component of the velocity we computed the horizontal and the vertical components along the arch filaments. For this purpose we reconstructed the three dimensional shape of the loops, assuming that they were symmetric with respect to the apex. Finally we have studied the motion of an inviscid isothermal plasma under the influence of gravity in an translational symmetric magnetic field. We considered a time varying flow along a steady loop. The solutions of the MHD eauations were compared with the observations of the material flow in the arch filaments.

  13. Practical Atmospheric Correction Algorithms for a Multi-Spectral Sensor From the Visible Through the Thermal Spectral Regions

    SciTech Connect

    Borel, C.C.; Villeneuve, P.V.; Clodium, W.B.; Szymenski, J.J.; Davis, A.B.

    1999-04-04

    Deriving information about the Earth's surface requires atmospheric corrections of the measured top-of-the-atmosphere radiances. One possible path is to use atmospheric radiative transfer codes to predict how the radiance leaving the ground is affected by the scattering and attenuation. In practice the atmosphere is usually not well known and thus it is necessary to use more practical methods. The authors will describe how to find dark surfaces, estimate the atmospheric optical depth, estimate path radiance and identify thick clouds using thresholds on reflectance and NDVI and columnar water vapor. The authors describe a simple method to correct a visible channel contaminated by a thin cirrus clouds.

  14. Influence of reduced carbon emissions and oxidation on the distribution of atmospheric CO2: Implications for inversion analyses

    Microsoft Academic Search

    Parvadha Suntharalingam; James T. Randerson; Nir Krakauer; Jennifer A. Logan; Daniel J. Jacob

    2005-01-01

    Recent inverse analyses constraining carbon fluxes using atmospheric CO2 observations have assumed that the CO2 source from atmospheric oxidation of reduced carbon is released at the surface rather than distributed globally in the atmosphere. This produces a bias in the estimates of surface fluxes. We used a three-dimensional (3D) atmospheric chemistry model (GEOS-CHEM) to evaluate the magnitude of this effect

  15. Post-doctoral position at LMD Palaiseau "Regional modelling of atmospheric composition over the Euro-Mediterranean area: focus on the sea-

    E-print Network

    Menut, Laurent

    Post-doctoral position at LMD Palaiseau "Regional modelling of atmospheric composition over as possible. Period of 18 months. Salary will be according to experience, within the CNRS band for post-doctoral researchers (1800-2200 Euros per month, after taxes). Applications are invited from post-doctoral researchers

  16. COMPARISON OF AIRCRAFT-AND TOWER-MEASURED FLUXES ACQUIRED DURING SMACEX WITH PREDICTIONS FROM A REGIONAL ATMOSPHERE-LAND EXCHANGE MODEL

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Soil Moisture - Atmosphere Coupling Experiment (SMACEX) was conducted 15 June -13 July 2002 in the Walnut Creek Watershed near Ames, Iowa - an agricultural region dominated by corn and soybean production. A primary goal in SMACEX was to study the role of heterogeneity in soil moisture and veget...

  17. Comparison of atmospheric transmittance measurements in the 3- to 5- and 8- to 12-um spectral regions with MODTRAN: considerations for long near-horizontal path geometries

    Microsoft Academic Search

    Anthony J. Ratkowski; Gail P. Anderson; Adam D. Devir

    1999-01-01

    Radiance measurements conducted from a high-altitude platform to retrieve surface properties will potentially involve long, near-horizontal viewing geometries. The computer code MODTRAN is widely used for the prediction of the propagation of infrared radiation through the lower atmosphere. Consequently, we have undertaken to test the predictions of MODTRAN for the 3 - 5 and 8 - 12 micron spectral regions

  18. The influence of forest shelterbelts on 137Cs fallout in Chernobyl affected areas (Tula region, Russia).

    NASA Astrophysics Data System (ADS)

    Ivanov, Maxim; Shamshurina, Eugeniya; Tatyana, Paramonova; Vladimir, Belyaev; Angelina, Gavruchenkova; Nikolai, Lugovoy; Konstantinov, Pavel

    2015-04-01

    The radioactive fallout after Chernobyl accident caused serious contamination by 137Cs along extensive area of East-European plain.Cs137 fall down on earth surface in two ways: gravitational - "dry" and rainfall - "wet" way. "Dry" fallout is a result of direct deposition of radionuclides from atmosphere with average speed of about 0.1-1 mm/sec. The fate of "dry fall"is far less than rainfall mechanism. Erupted water steam of reactor zone full of radioactive material enriched precipitation with 137Cs. Therefore, the derived spatial structure of contamination was under control of rainfall pattern in May-June 1986. On the areas affected by rainfall fallout was the Southern part of Tula region in Middle Russia. It got name as "Plava hot spot" by the town in the center of this area. Tula is a traditional rural region, the vast areas covered by chernozem soils are cultivated for centuries. During cultivation forest cover was reduced that urged growth of wind erosion and loss of soil fertility. Hence, in the middle of 20 the century large arrangements for creation of forest shelterbelts were conducted. High efficiency of shelterbelts made them a widely provided part of new human-transformed landscape. Usually shelterbelts are set as a regular network across main direction of winds in particular region. Such organization help to reduce speed of air steam in the lowest 20-30 m layer of atmosphere. In addition, shelterbelts are very good collectors of snow in winter time which increase total moisture of soil and its fertility. Represented investigation is conducted to find out any correlation between shelterbelts and fallout of radionuclides. If such correlation is significant, it has to be taken into account for further environmental surveys. Two shelterbelts on the interfluve positions were chosen for detailed examination. Both selected objects emerged before 1986 but have different width, floristic composition, orientation and type of construction. One of shelterbelts is consist of two perpendicular lines forming right angle. Sample of soil were collected inside the and within rectangular network on the sides from the shelterbelt. The distance between sampling points included into network is 15 m for the closest to the shelterbelt point and 70 m for other point in adjacent field. Each sample contains upper 30-cm layer of soil. Inside shelterbelts samples were subdivided into three parts for layer of 0-10, 10-20, 20-30 cm deep. In group of points sampling was undertaken with description of soil sections. All samples were dried, sieved and examined with ?-spectrometer. After statistical analysis of obtained data we calculated spatial variability of 137Cs inventories and correlation between distance before shelterbelt and inventory was assessed. According to obtained results map of spatial distribution of 137Cs within observed areas were created.

  19. Influence of CO2 line profiles on radiative and radiative-convective equilibrium states of the Venus lower atmosphere

    NASA Astrophysics Data System (ADS)

    Takagi, M.; Suzuki, K.; Sagawa, H.; Baron, P.; Mendrok, J.; Kasai, Y.; Matsuda, Y.

    2010-06-01

    Influence of CO2 line profiles on vertical temperature distributions in the radiative and radiative-convective equilibria is examined in the Venus atmosphere. The CO2 opacity obtained by the Voigt (Lorentz) profile without the line cutoff is shown to be excessive since this opacity gives surface temperatures of about 860-1020 K in the radiative-convective equilibrium. On the other hand, the opacity obtained by the extremely sub-Lorentzian profiles of Pollack et al. (1993) and Tonkov et al. (1996) are underestimated; the surface temperature obtained with this opacity remains 600 K even in the radiative equilibrium. In this case, convection does not take place below the cloud layer because of the cloud opacity. It is also shown that Fukabori et al.'s (1986) and Meadows and Crisp's (1996) profiles, both of which have intermediate absorption coefficients, give temperature distributions close to the observed one in the radiative-convective equilibrium. In these cases, the convection layer extends from the surface to 30-50 km altitudes. Then, the temperature distribution below the cloud layer is determined by a dry adiabatic lapse rate and the temperature near the cloud bottom. The surface temperature in the radiative-convective equilibrium is strongly affected by the temperature near the cloud bottom in this situation. The detailed structure of the H2SO4 cloud must be taken into account to construct a realistic radiative transfer model.

  20. Quantifying the Influence of Random Errors in Turbulence Measurements on Scalar Similarity in the Atmospheric Surface Layer

    NASA Astrophysics Data System (ADS)

    Sun, Kang; Li, Dan; Tao, Lei; Zhao, Zhongkuo; Zondlo, Mark A.

    2015-06-01

    The influence of random errors in turbulence measurements on scalar similarity for temperature, water vapour, {CO}2 , and {NH}3 is investigated using two eddy-covariance datasets collected over a lake and a cattle feedlot. Three measures of scalar similarity, namely, the similarity constant in the flux-variance relationship, the correlation coefficient between two scalars and the relative transport efficiency, are examined. The uncertainty in the similarity constant Cs in the flux-variance relationship resulting from random errors in turbulence measurements is quantified based on error propagation analyses and a Monte-Carlo sampling method, which yields a distribution instead of a single value for Cs . For different scalars, the distributions of Cs are found to significantly overlap, implying that scalars are transported similarly under strongly unstable conditions. The random errors in the correlation coefficients between scalars and the relative transport efficiencies are also quantified through error propagation analyses, and they increase as the atmosphere departs from neutral conditions. Furthermore, the correlation coefficients between three scalars (water vapour, {CO}2 , and {NH}3 ) are statistically different from unity while the relative transport efficiencies are not, which highlights the difference between these two measures of scalar similarity. The results suggest that uncertainties in these measures of scalar similarity need to be quantified when using them to diagnose the existence of dissimilarity among different scalars.

  1. Magnetic resonance investigation of Zn{sub 1?x}Fe{sub x}O properties influenced by annealing atmosphere

    SciTech Connect

    Raita, O.; Popa, A.; Toloman, D.; Stan, M.; Giurgiu, L. M. [National Institute for Research and Development of Isotopic and Molecular Technologies Donath 65-103, 400293, Cluj-Napoca (Romania)] [National Institute for Research and Development of Isotopic and Molecular Technologies Donath 65-103, 400293, Cluj-Napoca (Romania)

    2013-11-13

    ZnO is an attractive system for a wide variety of practical applications, being a chemically stable oxide semiconductor. It has been shown that Fe doping produces ferromagnetic semiconductor at room temperature. This material, therefore, has the potential for use in spintronic devices such as spin transistors, spin light emitting diodes, very high density nonvolatile semiconductor memory and optical emitters. It is believed that oxygen vacancies and substitutional incorporation are important to produce ferromagnetism in semiconductor oxide doped with transition metal ions. The present paper reports detailed electron paramagnetic resonance investigations (EPR) of the samples in order to investigate how annealing atmosphere (Air and Argon) influenced the magnetic behavior of the samples. X-band electron paramagnetic resonance (EPR) studies of Fe{sup 3+} ions in Zn{sub 1?x}Fe{sub x}O powders with x = 1%, 3% is reported. These samples are interesting to investigate as Fe doping produce ferromagnetism in ZnO, making a promising ferromagnetic semi