WorldWideScience

Sample records for atmospheric dispersion modeling

  1. Stochastic models for atmospheric dispersion

    DEFF Research Database (Denmark)

    Ditlevsen, Ove Dalager

    2003-01-01

    Simple stochastic differential equation models have been applied by several researchers to describe the dispersion of tracer particles in the planetary atmospheric boundary layer and to form the basis for computer simulations of particle paths. To obtain the drift coefficient, empirical vertical...... velocity distributions that depend on height above the ground both with respect to standard deviation and skewness are substituted into the stationary Fokker/Planck equation. The particle position distribution is taken to be uniform *the well/mixed condition( and also a given dispersion coefficient...... variation by height is adopted. A particular problem for simulation studies with finite time steps is the construction of a reflection rule different from the rule of perfect reflection at the boundaries such that the rule complies with the imposed skewness of the velocity distribution for particle...

  2. Accident consequence assessments with different atmospheric dispersion models

    International Nuclear Information System (INIS)

    An essential aim of the improvements of the new program system UFOMOD for Accident Consequence Assessments (ACAs) was to substitute the straight-line Gaussian plume model conventionally used in ACA models by more realistic atmospheric dispersion models. To identify improved models which can be applied in ACA codes and to quantify the implications of different dispersion models on the results of an ACA, probabilistic comparative calculations with different atmospheric dispersion models have been performed. The study showed that there are trajectory models available which can be applied in ACAs and that they provide more realistic results of ACAs than straight-line Gaussian models. This led to a completely novel concept of atmospheric dispersion modelling in which two different distance ranges of validity are distinguished: the near range of some ten kilometres distance and the adjacent far range which are assigned to respective trajectory models. (orig.)

  3. Atmospheric Dispersion Model Validation in Low Wind Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Sawyer, Patrick

    2007-11-01

    Atmospheric plume dispersion models are used for a variety of purposes including emergency planning and response to hazardous material releases, determining force protection actions in the event of a Weapons of Mass Destruction (WMD) attack and for locating sources of pollution. This study provides a review of previous studies that examine the accuracy of atmospheric plume dispersion models for chemical releases. It considers the principles used to derive air dispersion plume models and looks at three specific models currently in use: Aerial Location of Hazardous Atmospheres (ALOHA), Emergency Prediction Information Code (EPIcode) and Second Order Closure Integrated Puff (SCIPUFF). Results from this study indicate over-prediction bias by the EPIcode and SCIPUFF models and under-prediction bias by the ALOHA model. The experiment parameters were for near field dispersion (less than 100 meters) in low wind speed conditions (less than 2 meters per second).

  4. Analysis of software for modeling atmospheric dispersion

    International Nuclear Information System (INIS)

    During last few years, a number software packages for microcomputes have appeared with the aim to simulate diffusion of atmospheric pollutants. These codes, simplifying the models used for safety analyses of industrial plants are becoming more useful, and are even used for post-accidental conditions. The report presents for the first time in a critical manner, principal models available up to this date. The problem arises in adapting the models to the demanded post-accidental interventions. In parallel to this action an analysis of performance was performed. It means, identifying the need of forecasting the most appropriate actions to be performed having in mind short available time and lack of information. Because of these difficulties, it is possible to simplify the software, which will not include all the options but could deal with a specific situation. This would enable minimisation of data to be collected on the site

  5. Atmospheric dispersion models for application in relation to radionuclide releases

    International Nuclear Information System (INIS)

    In this document, a state-of-art review of dispersion models relevant to local, regional and global scales and applicable to radionuclide discharges of a continuous and discontinuous nature is presented. The theoretical basis of the models is described in chapter 2, while the uncertainty inherent in model predictions is considered in chapter 6. Chapters 3 to 5 of this report describe a number of models for calculating atmospheric dispersion on local, regional and global scales respectively

  6. Atmospheric dispersion modeling near a roadway under calm meteorological conditions

    OpenAIRE

    Fallah Shorshani, Masoud; Seigneur, Christian; POLO REHN, Lucie; CHANUT, Hervé; PELLAN, Yann; Jaffrezo, Jean-Luc; CHARRON, Aurélie; Andre, Michel

    2015-01-01

    Atmospheric pollutant dispersion near sources is typically simulated by Gaussian models because of their efficient compromise between reasonable accuracy and manageable com- putational time. However, the standard Gaussian dispersion formula applies downwind of a source under advective conditions with a well-defined wind direction and cannot calculate air pollutant concentrations under calm conditions with fluctuating wind direction and/or upwind of the emission source. Attempts have been made...

  7. Meteorological Uncertainty of atmospheric Dispersion model results (MUD)

    DEFF Research Database (Denmark)

    Havskov Sørensen, Jens; Amstrup, Bjarne; Feddersen, Henrik;

    dispersion scenario. However, recent developments in numerical weather prediction (NWP) include probabilistic forecasting techniques, which can be utilised also for long-range atmospheric dispersion models. The ensemble statistical methods developed and applied to NWP models aim at describing the inherent...... uncertainties of the meteorological model results. These uncertainties stem from e.g. limits in meteorological observations used to initialise meteorological forecast series. By perturbing e.g. the initial state of an NWP model run in agreement with the available observational data, an ensemble...... of meteorological forecasts is produced from which uncertainties in the various meteorological parameters are estimated, e.g. probabilities for rain. Corresponding ensembles of atmospheric dispersion can now be computed from which uncertainties of predicted radionuclide concentration and deposition patterns can...

  8. Complex source rate estimation for atmospheric transport and dispersion models

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, L.L.

    1993-09-13

    The accuracy associated with assessing the environmental consequences of an accidental atmospheric release of radioactivity is highly dependent on our knowledge of the source release rate which is generally poorly known. This paper reports on a technique that integrates the radiological measurements with atmospheric dispersion modeling for more accurate source term estimation. We construct a minimum least squares methodology for solving the inverse problem with no a priori information about the source rate.

  9. A Atmospheric Dispersion Model for the Sudbury, Ontario, Area.

    Science.gov (United States)

    Huhn, Frank Jones

    1982-03-01

    A mathematical model was developed and tested to predict the relationship between sulphur oxide and trace metal emissions from smelters in the Sudbury, Ontario area, and atmospheric, precipitation, lake water and sediment chemistry. The model consists of atmospheric and lake chemistry portions. The atmospheric model is a Gaussian crosswind concentration distribution modification to a box model with a uniform vertical concentration gradient limited by a mixing height. In the near-field Briggs' plume rise and vertical dispersion terms are utilized. Oxidation, wet and dry deposition mechanisms are included to account for the gas, liquid and solid phases separately. Important improvements over existing models include (1) near- and far-field conditions treated in a single model; (2) direct linkage of crosswind dispersion to hourly meteorological observations; (3) utilization of maximum to minimum range of input parameters to realistically model the range of outputs; (4) direct linkage of the atmospheric model to a lake model. Precipitation chemistry as calculated by the atmospheric model is related to lake water and sediment chemistry utilizing a mass balance approach and assuming a continuously stirred reactor (CSTR) model to describe lake circulation. All inputs are atmospheric, modified by hydrology, soil chemistry and sedimentation. Model results were tested by comparison with existing atmospheric and precipitation chemistry measurements, supplemented with analyses of lake water and sediment chemistry collected in a field program. Eight pollutant species were selected for modeling: sulphur dioxide, sulphate ion, hydrogen ion, copper, nickel, lead, zinc, and iron. The model effectively predicts precipitation chemistry within 150 km of Sudbury, with an average prediction to measurement ratio of 90 percent. Atmospheric concentrations are effectively predicted within 80 km, with an average prediction to measurement ratio of 81 percent. Lake chemistry predictions are

  10. Comparative calculations and validation studies with atmospheric dispersion models

    International Nuclear Information System (INIS)

    This report presents the results of an intercomparison of different mesoscale dispersion models and measured data of tracer experiments. The types of models taking part in the intercomparison are Gaussian-type, numerical Eulerian, and Lagrangian dispersion models. They are suited for the calculation of the atmospherical transport of radionuclides released from a nuclear installation. For the model intercomparison artificial meteorological situations were defined and corresponding arithmetical problems were formulated. For the purpose of model validation real dispersion situations of tracer experiments were used as input data for model calculations; in these cases calculated and measured time-integrated concentrations close to the ground are compared. Finally a valuation of the models concerning their efficiency in solving the problems is carried out by the aid of objective methods. (orig./HP)

  11. Meteorological Uncertainty of atmospheric Dispersion model results (MUD)

    DEFF Research Database (Denmark)

    Havskov Sørensen, Jens; Amstrup, Bjarne; Feddersen, Henrik;

    . However, recent developments in numerical weather prediction (NWP) include probabilistic forecasting techniques, which can be utilised also for atmospheric dispersion models. The ensemble statistical methods developed and applied to NWP models aim at describing the inherent uncertainties...... of the meteorological model results. These uncertainties stem from e.g. limits in meteorological obser-vations used to initialise meteorological forecast series. By perturbing the initial state of an NWP model run in agreement with the available observa-tional data, an ensemble of meteorological forecasts is produced...

  12. Atmospheric dispersion modeling: Challenges of the Fukushima Daiichi response

    Energy Technology Data Exchange (ETDEWEB)

    Sugiyama, Gayle [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Nasstrom, John [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Pobanz, Brenda [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Foster, Kevin [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Simpson, Matthew [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Vogt, Phil [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Aluzzi, Fernando [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Homann, Steve [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2012-05-01

    In this research, the U.S. Department of Energy’s (DOE) National Atmospheric Release Advisory Center (NARAC) provided a wide range of predictions and analyses as part of the response to the Fukushima Daiichi Nuclear Power Plant accident including: daily Japanese weather forecasts and atmospheric transport predictions to inform planning for field monitoring operations and to provide U.S. government agencies with ongoing situational awareness of meteorological conditions; estimates of possible dose in Japan based on hypothetical U.S. Nuclear Regulatory Commission scenarios of potential radionuclide releases to support protective action planning for U.S. citizens; predictions of possible plume arrival times and dose levels at U.S. locations; and source estimation and plume model refinement based on atmospheric dispersion modeling and available monitoring data.

  13. The Atmospheric Radionuclide Transport Model (ARTM) - Validation of a long-term atmospheric dispersion model

    Science.gov (United States)

    Hettrich, Sebastian; Wildermuth, Hans; Strobl, Christopher; Wenig, Mark

    2016-04-01

    In the last couple of years, the Atmospheric Radionuclide Transport Model (ARTM) has been developed by the German Federal Office for Radiation Protection (BfS) and the Society for Plant and Reactor Security (GRS). ARTM is an atmospheric dispersion model for continuous long-term releases of radionuclides into the atmosphere, based on the Lagrangian particle model. This model, developed in the first place as a more realistic replacement for the out-dated Gaussian plume models, is currently being optimised for further scientific purposes to study atmospheric dispersion in short-range scenarios. It includes a diagnostic wind field model, allows for the application of building structures and multiple sources (including linear, 2-and 3-dimensional source geometries), and considers orography and surface roughness. As an output it calculates the activity concentration, dry and wet deposition and can model also the radioactive decay of Rn-222. As such, ARTM requires to undergo an intense validation process. While for short-term and short-range models, which were mainly developed for examining nuclear accidents or explosions, a few measurement data-sets are available for validation, data-sets for validating long-term models are very sparse and the existing ones mostly prove to be not applicable for validation. Here we present a strategy for the validation of long-term Lagrangian particle models based on the work with ARTM. In our validation study, the first part we present is a comprehensive analysis of the model sensitivities on different parameters like e.g. (simulation grid size resolution, starting random number, amount of simulation particles, etc.). This study provides a good estimation for the uncertainties of the simulation results and consequently can be used to generate model outputs comparable to the available measurements data at various distances from the emission source. This comparison between measurement data from selected scenarios and simulation results

  14. Atmospheric dispersion modelling over complex terrain at small scale

    Science.gov (United States)

    Nosek, S.; Janour, Z.; Kukacka, L.; Jurcakova, K.; Kellnerova, R.; Gulikova, E.

    2014-03-01

    Previous study concerned of qualitative modelling neutrally stratified flow over open-cut coal mine and important surrounding topography at meso-scale (1:9000) revealed an important area for quantitative modelling of atmospheric dispersion at small-scale (1:3300). The selected area includes a necessary part of the coal mine topography with respect to its future expansion and surrounding populated areas. At this small-scale simultaneous measurement of velocity components and concentrations in specified points of vertical and horizontal planes were performed by two-dimensional Laser Doppler Anemometry (LDA) and Fast-Response Flame Ionization Detector (FFID), respectively. The impact of the complex terrain on passive pollutant dispersion with respect to the prevailing wind direction was observed and the prediction of the air quality at populated areas is discussed. The measured data will be used for comparison with another model taking into account the future coal mine transformation. Thus, the impact of coal mine transformation on pollutant dispersion can be observed.

  15. Atmospheric mercury dispersion modelling from two nearest hypothetical point sources

    Directory of Open Access Journals (Sweden)

    Khandakar Md Habib Al Razi, Moritomi Hiroshi, Kambara Shinji

    2012-01-01

    Full Text Available The Japan coastal areas are still environmentally friendly, though there are multiple air emission sources originating as a consequence of several developmental activities such as automobile industries, operation of thermal power plants, and mobile-source pollution. Mercury is known to be a potential air pollutant in the region apart from SOX, NOX, CO and Ozone. Mercury contamination in water bodies and other ecosystems due to deposition of atmospheric mercury is considered a serious environmental concern. Identification of sources contributing to the high atmospheric mercury levels will be useful for formulating pollution control and mitigation strategies in the region. In Japan, mercury and its compounds were categorized as hazardous air pollutants in 1996 and are on the list of "Substances Requiring Priority Action" published by the Central Environmental Council of Japan. The Air Quality Management Division of the Environmental Bureau, Ministry of the Environment, Japan, selected the current annual mean environmental air quality standard for mercury and its compounds of 0.04 μg/m3. Long-term exposure to mercury and its compounds can have a carcinogenic effect, inducing eg, Minamata disease. This study evaluates the impact of mercury emissions on air quality in the coastal area of Japan. Average yearly emission of mercury from an elevated point source in this area with background concentration and one-year meteorological data were used to predict the ground level concentration of mercury. To estimate the concentration of mercury and its compounds in air of the local area, two different simulation models have been used. The first is the National Institute of Advanced Science and Technology Atmospheric Dispersion Model for Exposure and Risk Assessment (AIST-ADMER that estimates regional atmospheric concentration and distribution. The second is the Hybrid Single Particle Lagrangian Integrated trajectory Model (HYSPLIT that estimates the

  16. Atmospheric dispersion models help to improve air quality; Los modelos de dispersion atmosferica ayudan a mejorar la calidad del aire

    Energy Technology Data Exchange (ETDEWEB)

    Martin, F.

    2013-07-01

    One of the main challenges of the atmospheric sciences is to reproduce as well as possible the phenomena and processes of pollutants in the atmosphere. To do it, mathematical models based in this case on fluid dynamics and mass and energy conservation equations, equations that govern the atmospheric chemistry, etc., adapted to the spatial scales to be simulated, are developed. The dispersion models simulate the processes of transport, dispersion, chemical transformation and elimination by deposition that air pollutants undergo once they are emitted. Atmospheric dispersion models with their multiple applications have become essential tools for the air quality management. (Author)

  17. Global atmospheric dispersion modelling after the Fukushima accident

    Energy Technology Data Exchange (ETDEWEB)

    Suh, K.S.; Youm, M.K.; Lee, B.G.; Min, B.I. [Korea Atomic Energy Research Institute (Korea, Republic of); Raul, P. [Universidad de Sevilla (Spain)

    2014-07-01

    A large amount of radioactive material was released to the atmosphere due to the Fukushima nuclear accident in March 2011. The radioactive materials released into the atmosphere were mostly transported to the Pacific Ocean, but some of them were fallen on the surface due to dry and wet depositions in the northwest area from the Fukushima nuclear site. Therefore, northwest part of the nuclear site was seriously contaminated and it was designated with the restricted zone within a radius of 20 ∼ 30 km around the Fukushima nuclear site. In the early phase of the accident from 11 March to 30 March, the radioactive materials were dispersed to an area of the inland and offshore of the nuclear site by the variations of the wind. After the Fukushima accident, the radionuclides were detected through the air monitoring in the many places over the world. The radioactive plume was transported to the east part off the site by the westerly jet stream. It had detected in the North America during March 17-21, in European countries during March 23-24, and in Asia during from March 24 to April 6, 2011. The radioactive materials were overall detected across the northern hemisphere passed by 15 ∼ 20 days after the accident. Three dimensional numerical model was applied to evaluate the dispersion characteristics of the radionuclides released into the air. Simulated results were compared with measurements in many places over the world. Comparative results had good agreements in some places, but they had a little differences in some locations. The difference between the calculations and measurements are due to the meteorological data and relatively coarse resolutions in the model. Some radioactive materials were measured in Philippines, Taiwan, Hon Kong and South Korea during from March 23-28. It inferred that it was directly transported from the Fukushima by the northeastern monsoon winds. This event was well represented in the numerical model. Generally, the simulations had a good

  18. A model for long range atmospheric dispersion of radionuclides released over a short period

    International Nuclear Information System (INIS)

    This report is the fourth in a series which gives practical guidance on the estimation of the dispersion of radioactive material released to the atmosphere. It represents the conclusions of a Working Group established to review recent developments in atmospheric dispersion modelling and to propose models for use within the UK. This report describes a model considered suitable for calculating dispersion at long range from releases of short duration. (author)

  19. Modelling of pollution dispersion in atmosphere; Modelowanie procesow propagacji skazen w atmosferze

    Energy Technology Data Exchange (ETDEWEB)

    Borysiewicz, M.; Stankiewicz, R.

    1994-12-31

    The paper contains the review of the mathematical foundation of atmospheric dispersion models. The atmospheric phenomena relevant to atmospheric dispersion model are discussed. In particular the parametrization of processes with time and space scales smaller than numerical grid size, limited by available computer power, is presented. The special attention was devoted to similarity theory and parametrization of boundary layer. The numerical methods are analysed and the drawbacks of the method are presented. (author). 99 refs, 15 figs, 3 tabs.

  20. Simplified Atmospheric Dispersion Model andModel Based Real Field Estimation System ofAir Pollution

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    The atmospheric dispersion model has been well developed and applied in pollution emergency and prediction. Based on thesophisticated air diffusion model, this paper proposes a simplified model and some optimization about meteorological andgeological conditions. The model is suitable for what is proposed as Real Field Monitor and Estimation system. The principle ofsimplified diffusion model and its optimization is studied. The design of Real Field Monitor system based on this model and itsfundamental implementations are introduced.

  1. A comparison of Gaussian and diffusivity models of atmospheric dispersion

    International Nuclear Information System (INIS)

    The Gaussian plume diffusion model of Smith and a diffusivity model by Maul are compared over the full range of atmospheric stability. The models' predictions for ground level concentration are found to agree well a) for ground level releases of materials, and b) for elevated releases of material at distances comparable to or greater than the distance of maximum ground level concentration. Surface layer, ground roughness, and dry deposition effects are examined and a simple ground deposition model used in the Gaussian plume model is found to be adequate over most of the stability range. Uncertainties due to the models themselves and the meteorological input data are estimated and the advantages and limitations of both types of model are discussed. It is concluded that the models are suitable for a variety of applications and that they are fast and inexpensive to run as computer models. (author)

  2. National Atmospheric Release Advisory Center Dispersion Modeling of the Full-scale Radiological Dispersal Device (FSRDD) Field Trials.

    Science.gov (United States)

    Neuscamman, Stephanie; Yu, Kristen

    2016-05-01

    The results of the National Atmospheric Release Advisory Center (NARAC) model simulations are compared to measured data from the Full-Scale Radiological Dispersal Device (FSRDD) field trials. The series of explosive radiological dispersal device (RDD) experiments was conducted in 2012 by Defence Research and Development Canada (DRDC) and collaborating organizations. During the trials, a wealth of data was collected, including a variety of deposition and air concentration measurements. The experiments were conducted with one of the stated goals being to provide measurements to atmospheric dispersion modelers. These measurements can be used to facilitate important model validation studies. For this study, meteorological observations recorded during the tests are input to the diagnostic meteorological model, ADAPT, which provides 3-D, time-varying mean wind and turbulence fields to the LODI dispersion model. LODI concentration and deposition results are compared to the measured data, and the sensitivity of the model results to changes in input conditions (such as the particle activity size distribution of the source) and model physics (such as the rise of the buoyant cloud of explosive products) is explored. The NARAC simulations predicted the experimentally measured deposition results reasonably well considering the complexity of the release. Changes to the activity size distribution of the modeled particles can improve the agreement of the model results to measurement.

  3. Atmospheric aerosol dispersion models and their applications to environmental risk assessment

    Directory of Open Access Journals (Sweden)

    Andrzej Mazur

    2014-03-01

    Full Text Available Introduction. Numerical models of dispersion of atmospheric pollutants are widely used to forecast the spread of contaminants in the air and to analyze the effects of this phenomenon. The aim of the study is to investigate the possibilities and the quality of diagnosis and prediction of atmospheric transport of aerosols in the air using the dispersion model of atmospheric pollutants, developed at the Institute of Meteorology and Water Management (IMWM in Warsaw. Material and methods. A model of the dispersion of atmospheric pollutants, linked with meteorological models in a diagnostic mode, was used to simulate the transport of the cloud of aerosols released during the crash near the town of Ożydiw (Ukraine and of volcanic ash – during the volcanic eruption of Eyjafjallajökull in Iceland. Results. Possible directions of dispersion of pollutants in the air and its concentration in the atmosphere and deposition to the soil were assessed. The analysis of temporal variability of concentrations of aerosols in the atmosphere confirmed that the model developed at IMWM is an effective tool for diagnosis of air quality in the area of Poland as well as for determination of exposure duration to the aerosol clouds for different weather scenarios. Conclusions. The results are a confirmation of the thesis, that because in the environmental risk assessment, an important element is not only current information on the level of pollution concentrations, but also the time of exposure to pollution and forecast of these elements, and consequently the predicted effects on man or the environment in general; so it is necessary to use forecasting tools, similar to presented application. The dispersion model described in the paper is an operational tool for description, analysis and forecasting of emergency situations in case of emissions of hazardous substances.

  4. Atmospheric Dispersion Simulation for Level 3 PSA at Ulchin Nuclear Site using a PUFF model

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung Jun; Han, Seok-Jung; Jeong, Hyojoon; Jang, Seung-Cheol [KAERI, Daejeon (Korea, Republic of)

    2015-05-15

    Air dispersion prediction is a key in the level 3 PSA to predict radiation releases into the environment for preparing an effective strategy for an evacuation as a basis of the emergency preparedness. To predict the atmospheric dispersion accurately, the specific conditions of the radiation release location should be considered. There are various level 3 PSA tools and MACSS2 is one of the widely used level 3 PSA tools in many countries including Korea. Due to the characteristics of environmental conditions in Korea, it should be demonstrated that environmental conditions of Korea nuclear sites can be appropriately illustrated by the tool. In Korea, because all nuclear power plants are located on coasts, sea and land breezes might be a significant factor. The objectives of this work is to simulate the atmospheric dispersion for Ulchin nuclear site in Korea using a PUFF model and to generate the data which can be used for the comparison with that of PLUME model. A nuclear site has own atmospheric dispersion characteristics. Especially in Korea, nuclear sites are located at coasts and it is expected that see and land breeze effects are relatively high. In this work, the atmospheric dispersion at Ulchin nuclear site was simulated to evaluate the effect of see and land breezes in four seasons. In the simulation results, it was observed that the wind direction change with time has a large effect on atmospheric dispersion. If the result of a PLUME model is more conservative than most severe case of a PUFF model, then the PLUME model could be used for Korea nuclear sites in terms of safety assessment.

  5. Atmospheric Dispersion Simulation for Level 3 PSA at Ulchin Nuclear Site using a PUFF model

    International Nuclear Information System (INIS)

    Air dispersion prediction is a key in the level 3 PSA to predict radiation releases into the environment for preparing an effective strategy for an evacuation as a basis of the emergency preparedness. To predict the atmospheric dispersion accurately, the specific conditions of the radiation release location should be considered. There are various level 3 PSA tools and MACSS2 is one of the widely used level 3 PSA tools in many countries including Korea. Due to the characteristics of environmental conditions in Korea, it should be demonstrated that environmental conditions of Korea nuclear sites can be appropriately illustrated by the tool. In Korea, because all nuclear power plants are located on coasts, sea and land breezes might be a significant factor. The objectives of this work is to simulate the atmospheric dispersion for Ulchin nuclear site in Korea using a PUFF model and to generate the data which can be used for the comparison with that of PLUME model. A nuclear site has own atmospheric dispersion characteristics. Especially in Korea, nuclear sites are located at coasts and it is expected that see and land breeze effects are relatively high. In this work, the atmospheric dispersion at Ulchin nuclear site was simulated to evaluate the effect of see and land breezes in four seasons. In the simulation results, it was observed that the wind direction change with time has a large effect on atmospheric dispersion. If the result of a PLUME model is more conservative than most severe case of a PUFF model, then the PLUME model could be used for Korea nuclear sites in terms of safety assessment

  6. Objectives for next generation of practical short-range atmospheric dispersion models

    International Nuclear Information System (INIS)

    The proceedings contains papers from the workshop ''Objectives for Next Generation of Practical Short-Range Atmospheric Dispersion Models''. They deal with two types of models, namely models for regulatory purposes and models for real-time applications. The workshop was the result of an action started in 1991 for increased cooperation and harmonization within atmospheric dispersion modelling. The focus of the workshop was on the management of model development and the definition of model objectives, rather than on detailed model contents. It was the intention to identify actions that can be taken in order to improve the development and use of atmospheric dispersion models. The papers in the proceedings deal with various topics within the broad spectrum of matters related to up-to-date practical models, such as their scientific basis, requirements for model input and output, meteorological preprocessing, standardisation within modelling, electronic information exchange as a potentially useful tool, model evaluation and data bases for model evaluation. In addition to the papers, the proceedings contain summaries of the discussions at the workshop. These summaries point to a number of recommended actions which can be taken in order to improve ''modelling culture''. (AB)

  7. A new formulation of the probability density function in random walk models for atmospheric dispersion

    DEFF Research Database (Denmark)

    Falk, Anne Katrine Vinther; Gryning, Sven-Erik

    1997-01-01

    In this model for atmospheric dispersion particles are simulated by the Langevin Equation, which is a stochastic differential equation. It uses the probability density function (PDF) of the vertical velocity fluctuations as input. The PDF is constructed as an expansion after Hermite polynomials...

  8. Using meteorological ensembles for atmospheric dispersion modelling of the Fukushima nuclear accident

    Science.gov (United States)

    Périllat, Raphaël; Korsakissok, Irène; Mallet, Vivien; Mathieu, Anne; Sekiyama, Thomas; Didier, Damien; Kajino, Mizuo; Igarashi, Yasuhito; Adachi, Kouji

    2016-04-01

    Dispersion models are used in response to an accidental release of radionuclides of the atmosphere, to infer mitigation actions, and complement field measurements for the assessment of short and long term environmental and sanitary impacts. However, the predictions of these models are subject to important uncertainties, especially due to input data, such as meteorological fields or source term. This is still the case more than four years after the Fukushima disaster (Korsakissok et al., 2012, Girard et al., 2014). In the framework of the SAKURA project, an MRI-IRSN collaboration, a meteorological ensemble of 20 members designed by MRI (Sekiyama et al. 2013) was used with IRSN's atmospheric dispersion models. Another ensemble, retrieved from ECMWF and comprising 50 members, was also used for comparison. The MRI ensemble is 3-hour assimilated, with a 3-kilometers resolution, designed to reduce the meteorological uncertainty in the Fukushima case. The ECMWF is a 24-hour forecast with a coarser grid, representative of the uncertainty of the data available in a crisis context. First, it was necessary to assess the quality of the ensembles for our purpose, to ensure that their spread was representative of the uncertainty of meteorological fields. Using meteorological observations allowed characterizing the ensembles' spread, with tools such as Talagrand diagrams. Then, the uncertainty was propagated through atmospheric dispersion models. The underlying question is whether the output spread is larger than the input spread, that is, whether small uncertainties in meteorological fields can produce large differences in atmospheric dispersion results. Here again, the use of field observations was crucial, in order to characterize the spread of the ensemble of atmospheric dispersion simulations. In the case of the Fukushima accident, gamma dose rates, air activities and deposition data were available. Based on these data, selection criteria for the ensemble members were

  9. Some puff modelling principles relevant for dispersion calculations in the atmosphere

    International Nuclear Information System (INIS)

    Some basic principles for a computational puff-model for prediction and simulation of atmospheric dispersion are discussed. The constraints imposed by use of a single point measurement of the windfield for advection of puffs are examined. A simple scheme for simulation of a more realistic windfield is proposed. One example of the use of a puff-model is shown and comparison is made with an ordinary Gaussian plume model. (author)

  10. Atmospheric transport and dispersion modeling for the Hanford Environmental Dose Reconstruction Project

    International Nuclear Information System (INIS)

    Radiation doses that may have resulted from operations at the Hanford Site are being estimated in the Hanford Environmental Dose Reconstruction (HEDR) Project. One of the project subtasks, atmospheric transport, is responsible for estimating the transport, diffusion and deposition of radionuclides released to the atmosphere. This report discusses modeling transport and diffusion in the atmospheric pathway. It is divided into three major sections. The first section of the report presents the atmospheric modeling approach selected following discussion with the Technical Steering Panel that directs the HEDR Project. In addition, the section discusses the selection of the MESOI/MESORAD suite of atmospheric dispersion models that form the basis for initial calculations and future model development. The second section of the report describes alternative modeling approaches that were considered. Emphasis is placed on the family of plume and puff models that are based on Gaussian solution to the diffusion equations. The final portion of the section describes the performance of various models. The third section of the report discusses factors that bear on the selection of an atmospheric transport modeling approach for HEDR. These factors, which include the physical setting of the Hanford Site and the available meteorological data, serve as constraints on model selection. Five appendices are included in the report. 39 refs., 4 figs., 2 tabs

  11. Description and validation of ERAD: An atmospheric dispersion model for high explosive detonations

    Energy Technology Data Exchange (ETDEWEB)

    Boughton, B.A.; DeLaurentis, J.M.

    1992-10-01

    The Explosive Release Atmospheric Dispersion (ERAD) model is a three-dimensional numerical simulation of turbulent atmospheric transport and diffusion. An integral plume rise technique is used to provide a description of the physical and thermodynamic properties of the cloud of warm gases formed when the explosive detonates. Particle dispersion is treated as a stochastic process which is simulated using a discrete time Lagrangian Monte Carlo method. The stochastic process approach permits a more fundamental treatment of buoyancy effects, calm winds and spatial variations in meteorological conditions. Computational requirements of the three-dimensional simulation are substantially reduced by using a conceptualization in which each Monte Carlo particle represents a small puff that spreads according to a Gaussian law in the horizontal directions. ERAD was evaluated against dosage and deposition measurements obtained during Operation Roller Coaster. The predicted contour areas average within about 50% of the observations. The validation results confirm the model`s representation of the physical processes.

  12. A model for short and medium range dispersion of radionuclides released to the atmosphere

    International Nuclear Information System (INIS)

    A Working Group was established to give practical guidance on the estimation of the dispersion of radioactive releases to the atmosphere. The dispersion is estimated in the short and medium range, that is from about 100 m to a few tens of kilometres from the source, and is based upon a Gaussian plume model. A scheme is presented for categorising atmospheric conditions and values of the associated dispersion parameters are given. Typical results are presented for releases in specific meteorological conditions and a scheme is included to allow for durations of release of up to 24 hours. Consideration has also been given to predicting longer term average concentrations, typically annual averages, and results are presented which facilitate site specific calculations. The results of the models are extended to 100 km from the source, but the increasing uncertainty with which results may be predicted beyond a few tens of kilometres from the source is emphasised. Three technical appendices provide some of the rationale behind the decisions made in adopting the various models in the proposed dispersion scheme. (author)

  13. ATMES: An evaluation of long range atmospheric dispersion models using radioactivity data from the Chernobyl accident

    International Nuclear Information System (INIS)

    ATMES was organized in 1989 by CEC, WMO and IAEA with the main purpose of reviewing and calibrating long range atmospheric dispersion models, to identify the more successful approaches. This document provides some findings of the study which employed 21 models from various institutions of 14 countries. They had to produce the model results without knowing in advance the measurements to which their results had to be compared. Many out of the participating models were able to predict the arrival times at the two selected sites using the analysed windfields within a few hours

  14. Numerical modelling of pollution dispersion in 3D atmospheric boundary layer

    Energy Technology Data Exchange (ETDEWEB)

    Benes, L.; Bodnar, T.; Kozel, K. [Czech Technical Univ. of Prague (Czech Republic). Dept. of Technical Mathematics; Fraunie, Ph. [Univ. de Toulon et du Var, La Garde (France). Lab. de Sondages Electromagnetiques et Environnemental Terrestre

    2002-07-01

    The main goal of this work is to present the applicable models and numerical methods for solution of flow and pollution dispersion in 3D atmospheric boundary layer (ABL). Mathematical models are based on the system of Reynolds averaged Navier-Stokes equations and its simplifications. The sets of governing equations are completed by the transport equations for passive impurities and potential temperature. A simple algebraic turbulent closure model is used. The thermal stability phenomenon is taken into account. For each mathematical model a numerical scheme based on finite-difference or finite-volume discretization is proposed and discussed. Some results of numerical tests are presented for pollution dispersion from point sources and flows over simple geometries. (orig.)

  15. The use of atmospheric dispersion models in risk assessment decision support systems for pesticides

    NARCIS (Netherlands)

    Leeuw, de F.A.A.M.; Pul, van W.A.J.; Berg, van den F.; Gilbert, A.J.

    2000-01-01

    In the evaluation of potentially adverse effects of organic chemicals such as pesticides on the environment the atmosphere may play an important role. After its release to the atmosphere the chemical will be transported/dispersed in the atmosphere andfinally it will be removed either by atmospheric-

  16. Impact of atmospheric release in stable night meteorological conditions; can emergency models predict dispersion

    International Nuclear Information System (INIS)

    Atmospheric dispersion of pollutant or radionuclides in stratified meteorological condition, i.e. especially when weather conditions are very stable, mainly at night, is still poorly understood and not well apprehended by the operational atmospheric dispersion models. However, correctly predicting the dispersion of a radioactive plume, and estimating the radiological consequences for the population, following an unplanned atmospheric release of radionuclides are crucial steps in an emergency response. To better understand dispersion in these special weather conditions, IRSN performed a series of 22 air sampling campaigns between 2010 and 2013 in the vicinity of the La Hague nuclear reprocessing plant (AREVA - NC, France), at distances between 200 m and 3000 m from the facility. Krypton-85 (85Kr), a b-and g-emitting radionuclide, released during the reprocessing of spent nuclear fuel was used as a non-reactive tracer of radioactive plumes. Experimental campaigns were realized in stability class stable or very stable (E or F according to Pasquill classification) 18 times, and in neutral conditions (D according to Pasquill classification) 4 times. During each campaign, Krypton-85 real time measurement were made to find the plume around the plant, and then integrated samples (30 min) were collected in bag perpendicularly to the assumed wind direction axis. After measurement by gamma spectrometry, we have, when it was possible, estimate the point of impact and the width of the plume. The objective was to estimate the horizontal dispersion (width) of the plume at ground level in function of the distance and be able to calculate atmospheric transfer coefficients. In a second step, objective was to conclude on the use of common model and on their uncertainties. The results will be presented in terms of impact on the near-field. They will be compared with data obtained in previous years in neutral atmospheric conditions, and finally the results will be confronted with those

  17. Impact of atmospheric release in stable night meteorological conditions; can emergency models predict dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Connan, O.; Hebert, D.; Solier, L.; Voiseux, C.; Lamotte, M.; Laguionie, P.; Maro, D.; Thomas, L. [IRSN/PRP-ENV/SERIS/LRC (France)

    2014-07-01

    Atmospheric dispersion of pollutant or radionuclides in stratified meteorological condition, i.e. especially when weather conditions are very stable, mainly at night, is still poorly understood and not well apprehended by the operational atmospheric dispersion models. However, correctly predicting the dispersion of a radioactive plume, and estimating the radiological consequences for the population, following an unplanned atmospheric release of radionuclides are crucial steps in an emergency response. To better understand dispersion in these special weather conditions, IRSN performed a series of 22 air sampling campaigns between 2010 and 2013 in the vicinity of the La Hague nuclear reprocessing plant (AREVA - NC, France), at distances between 200 m and 3000 m from the facility. Krypton-85 ({sup 85}Kr), a b-and g-emitting radionuclide, released during the reprocessing of spent nuclear fuel was used as a non-reactive tracer of radioactive plumes. Experimental campaigns were realized in stability class stable or very stable (E or F according to Pasquill classification) 18 times, and in neutral conditions (D according to Pasquill classification) 4 times. During each campaign, Krypton-85 real time measurement were made to find the plume around the plant, and then integrated samples (30 min) were collected in bag perpendicularly to the assumed wind direction axis. After measurement by gamma spectrometry, we have, when it was possible, estimate the point of impact and the width of the plume. The objective was to estimate the horizontal dispersion (width) of the plume at ground level in function of the distance and be able to calculate atmospheric transfer coefficients. In a second step, objective was to conclude on the use of common model and on their uncertainties. The results will be presented in terms of impact on the near-field. They will be compared with data obtained in previous years in neutral atmospheric conditions, and finally the results will be confronted with

  18. Uncertainty modelling of atmospheric dispersion by stochastic response surface method under aleatory and epistemic uncertainties

    Indian Academy of Sciences (India)

    Rituparna Chutia; Supahi Mahanta; D Datta

    2014-04-01

    The parameters associated to a environmental dispersion model may include different kinds of variability, imprecision and uncertainty. More often, it is seen that available information is interpreted in probabilistic sense. Probability theory is a well-established theory to measure such kind of variability. However, not all available information, data or model parameters affected by variability, imprecision and uncertainty, can be handled by traditional probability theory. Uncertainty or imprecision may occur due to incomplete information or data, measurement error or data obtained from expert judgement or subjective interpretation of available data or information. Thus for model parameters, data may be affected by subjective uncertainty. Traditional probability theory is inappropriate to represent subjective uncertainty. Possibility theory is used as a tool to describe parameters with insufficient knowledge. Based on the polynomial chaos expansion, stochastic response surface method has been utilized in this article for the uncertainty propagation of atmospheric dispersion model under consideration of both probabilistic and possibility information. The proposed method has been demonstrated through a hypothetical case study of atmospheric dispersion.

  19. Estimation of tritium dispersion from the spent nuclear fuel reprocessing plant in Rokkasho using an atmospheric dispersion model

    Energy Technology Data Exchange (ETDEWEB)

    Abe, Koichi; Kakiuchi, Hideki; Iyogi, Takashi; Hisamatsu, Shun' ichi [Institute for Environmental Sciences, Rokkasho, Aomori 039-3212 (Japan); Akata, Naofumi [Institute for Environmental Sciences, Rokkasho, Aomori 039-3212 (Japan); National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Chiang, Jing-Hsien; Suwa, Hiroji [Japan NUS Co., Ltd., Tokyo 160-0023 (Japan)

    2014-07-01

    Japan's first large-scale commercial plant for reprocessing spent nuclear fuel was constructed in Rokkasho, Japan, by Japan Nuclear Fuel Limited (JNFL). Final tests of plant operation carried out with spent fuels since 31 March 2006 have indicated that small amounts of radionuclides (mainly {sup 3}H, {sup 14}C, {sup 85}Kr, and {sup 129}I) are discharged into the atmosphere from the main stack of the plant. To estimate the atmospheric dispersion of {sup 3}H discharged from the plant, we used a combination of the Fifth-Generation Penn State/NCAR Mesoscale Model (MM5) and the CG-MATHEW/ADPIC models, Version 5.0 (ARAC-2). Simulation results were validated with atmospheric {sup 3}H concentrations and wet deposition rates measured at the Institute for Environmental Sciences (IES), located 2.6 km east from the stack. Biweekly atmospheric HTO, HT, and CH3T samples and monthly precipitation samples were collected at IES from April 2006 to February 2009 (the test period). Concentrations of {sup 3}H in the samples were measured with a low-background liquid scintillation counter (LSC-LB5, Hitachi Aloka Medical, Ltd., Tokyo, Japan). To simulate the dispersion of {sup 3}H from the stack, a meteorological field was calculated by MM5 and used as input to ARAC-2, which consists of a mass-consistent wind model and a particle-tracing-type dispersion model. The simulation areas were 315 km x 315 km for MM5 and 50 km x 50 km for ARAC-2. The following meteorological data were input to MM5: grid point data derived from the Mesoscale Model of the Japan Meteorological Agency (JMA), data from JMA's Automated Meteorological Data Acquisition System (AMeDAS), and wind speed and direction at IES and JNFL measured every 10 min. The weekly discharge rates of {sup 3}H disclosed by JNFL were used as the source term for ARAC-2. The concentrations of {sup 3}H in atmospheric moisture and precipitation samples increased from their background values during the test period. As an index of

  20. Simulation of CO2 dispersion in the atmospheric boundary layer using a mesoscale model

    Science.gov (United States)

    Granvold, P. W.; Chow, F. K.; Oldenburg, C. M.

    2007-12-01

    The consequences of unexpected releases of CO2 from underground carbon sequestration sites must be understood before large-scale carbon capture and storage projects are implemented. Carbon dioxide gas can migrate through faults, fractures, or abandoned wells that penetrate the subsurface storage site and provide a pathway to the ground surface. Though such leakage is typically slow and in small amounts, CO2 can accumulate at the ground surface because it is denser than the surrounding atmosphere. Such accumulation presents health risks for humans and animals in the vicinity, and can cause damage to crops, trees, and other vegetation. Because atmospheric dispersion of CO2 is driven by gravity and ambient wind conditions, the danger from CO2 is greatest in regions with topographic depressions where the dense gas can pool, or under stably- stratified background atmospheric conditions which further inhibit mixing and dilution of the gas. We are developing a simulation tool for predictions of CO2 releases from underground storage sites in a mesoscale atmospheric model. The model solves the compressible fluid flow equations, and has been modified to account for transport of dense gases. Example simulations from sources of different release strengths over various topography and background atmospheric conditions illustrate the behavior of the model and its utility for risk assessment and certification of carbon sequestration sites.

  1. Modeling of High-altitude Atmospheric Dispersion Using Climate and Meteorological Forecast Data

    Energy Technology Data Exchange (ETDEWEB)

    Glascoe, L G; Chin, H S

    2005-03-30

    The overall objective of this study is to provide a demonstration of capability for importing both high altitude meteorological forecast and climatological datasets from NRL into the NARAC modeling system to simulate high altitude atmospheric droplet release and dispersion. The altitude of release for the proposed study is between 60 and 100km altitude. As either standard climatological data (over a period of 40 years) or daily meteorological forecasts can drive the particle dispersion model, we did a limited comparison of simulations with meteorological data and simulations with climatological data. The modeling tools used to address this problem are the National Atmospheric Release Advisory Center (NARAC) modeling system at LLNL which are operationally employed to assist DOE/DHS/DOD emergency response to an atmospheric release of chemical, biological, and radiological contaminants. The interrelation of the various data feeds and codes at NARAC are illustrated in Figure 1. The NARAC scientific models are all verified to both analytic solutions and other codes; the models are validated to field data such as the Prairie Grass study (Barad, 1958). NARAC has multiple real-time meteorological data feeds from the National Weather Service, from the European Center for Medium range Weather Forecasting, from the US Navy, and from the US Air Force. NARAC also keeps a historical archive of meteorological data partially for research purposes. The codes used in this effort were the Atmospheric Data Assimilation and Parameterization Techniques (ADAPT) model (Sugiyama and Chan, 1998) and a development version of the Langrangian Operational Dispersion Integrator (LODI) model (Nasstrom et al., 2000). The use of the NASA GEOS-4 dataset required the use of a development version of the Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS) model (Hodur, 1997; Chin and Glascoe, 2004). The specific goals of this study are the following: (1) Confirm data compatibility of NRL

  2. EVALUATION OF URBAN ATMOSPHERIC TRANSPORT AND DISPERSION MODELS USING DATA FROM THE JOINT URBAN 2003 FIELD EXPERIMENT

    OpenAIRE

    T. Urban, Jeffry; Warner, Steve; Platt, Nathan; F. Heagy, James

    2008-01-01

    Abstract: We have evaluated the performance of several urban atmospheric transport and dispersion models by comparing model predictions to tracer gas concentrations measured during the Joint Urban 2003 field experiment in Oklahoma City, USA. These models include the Urban Canopy, Urban Dispersion Model (UDM), and Micro-SWIFT/SPRAY (MSS) modes within the HPAC modelling suite, QUIC-URB/QUIC-PLUME models, and the MESO/RUSTIC models. We discuss some of the results of these comparisons...

  3. Modeling the fallout from stabilized nuclear clouds using the HYSPLIT atmospheric dispersion model

    International Nuclear Information System (INIS)

    The Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model, developed by the National Oceanic and Atmospheric Administration's Air Resources Laboratory, has been configured to simulate the dispersion and deposition of nuclear materials from a surface-based nuclear detonation using publicly available information on nuclear explosions. Much of the information was obtained from “The Effects of Nuclear Weapons” by Glasstone and Dolan (1977). The model was evaluated against the measurements of nuclear fallout from six nuclear tests conducted between 1951 and 1957 at the Nevada Test Site using the global NCEP/NCAR Reanalysis Project (NNRP) and the Weather Research and Forecasting (WRF) meteorological data as input. The model was able to reproduce the general direction and deposition patterns using the coarse NNRP data with Figure of Merit in Space (FMS – the percent overlap between predicted and measured deposition patterns) scores in excess of 50% for four of six simulations for the smallest dose rate contour, with FMS scores declining for higher dose rate contours. When WRF meteorological data were used the FMS scores were 5–20% higher in five of the six simulations, especially at the higher dose rate contours. The one WRF simulation where the scores declined slightly (10–30%) was also the best scoring simulation when using the NNRP data. When compared with measurements of dose rate and time of arrival from the Town Data Base (Thompson et al., 1994), similar results were found with the WRF simulations providing better results for four of six simulations. The overall result was that the different plume simulations using WRF data had more consistent performance than the plume simulations using NNRP data fields. - Highlights: • Modeled the fallout from six Nevada nuclear tests between 1951 and 1957 using HYSPLIT. • Modeled dose rate patterns compared favorably to measurements. • Plume overlap was best for the smallest dose rate

  4. Detailed source term estimation of the atmospheric release for the Fukushima Daiichi Nuclear Power Station accident by coupling simulations of atmospheric dispersion model with improved deposition scheme and oceanic dispersion model

    OpenAIRE

    G. Katata; Chino, M; T. Kobayashi; Terada, H.; Ota, M; Nagai, H.; M. Kajino; Draxler, R; M. C. Hort; Malo, A.; Torii, T.; Y. Sanada

    2014-01-01

    Temporal variations in the amount of radionuclides released into the atmosphere during the Fukushima Dai-ichi Nuclear Power Station (FNPS1) accident and their atmospheric and marine dispersion are essential to evaluate the environmental impacts and resultant radiological doses to the public. In this paper, we estimate a detailed time trend of atmospheric releases during the accident by combining environmental monitoring data with atmospheric model simulations from WSP...

  5. Evaluation of the Regional Atmospheric Modeling System in the Eastern Range Dispersion Assessment System

    Science.gov (United States)

    Case, Jonathan

    2000-01-01

    The Applied Meteorology Unit is conducting an evaluation of the Regional Atmospheric Modeling System (RAMS) contained within the Eastern Range Dispersion Assessment System (ERDAS). ERDAS provides emergency response guidance for operations at the Cape Canaveral Air Force Station and the Kennedy Space Center in the event of an accidental hazardous material release or aborted vehicle launch. The prognostic data from RAMS is available to ERDAS for display and is used to initialize the 45th Range Safety (45 SW/SE) dispersion model. Thus, the accuracy of the 45 SW/SE dispersion model is dependent upon the accuracy of RAMS forecasts. The RAMS evaluation task consists of an objective and subjective component for the Florida warm and cool seasons of 1999-2000. The objective evaluation includes gridded and point error statistics at surface and upper-level observational sites, a comparison of the model errors to a coarser grid configuration of RAMS, and a benchmark of RAMS against the widely accepted Eta model. The warm-season subjective evaluation involves a verification of the onset and movement of the Florida east coast sea breeze and RAMS forecast precipitation. This interim report provides a summary of the RAMS objective and subjective evaluation for the 1999 Florida warm season only.

  6. The Evaluation of the Regional Atmospheric Modeling System in the Eastern Range Dispersion Assessment System

    Science.gov (United States)

    Case, Jonathan

    2001-01-01

    The Applied Meteorology Unit (AMU) evaluated the Regional Atmospheric Modeling System (RAMS) contained within the Eastern Range Dispersion Assessment System (ERDAS). ERDAS provides emergency response guidance for Cape Canaveral Air Force Station and Kennedy Space Center operations in the event of an accidental hazardous material release or aborted vehicle launch. The RAMS prognostic data are available to ERDAS for display and are used to initialize the 45th Space Wing/Range Safety dispersion model. Thus, the accuracy of the dispersion predictions is dependent upon the accuracy of RAMS forecasts. The RAMS evaluation consisted of an objective and subjective component for the 1999 and 2000 Florida warm seasons, and the 1999-2000 cool season. In the objective evaluation, the AMU generated model error statistics at surface and upper-level observational sites, compared RAMS errors to a coarser RAMS grid configuration, and benchmarked RAMS against the nationally-used Eta model. In the subjective evaluation, the AMU compared forecast cold fronts, low-level temperature inversions, and precipitation to observations during the 1999-2000 cool season, verified the development of the RAMS forecast east coast sea breeze during both warm seasons, and examined the RAMS daily thunderstorm initiation and precipitation patterns during the 2000 warm season. This report summarizes the objective and subjective verification for all three seasons.

  7. Testing the atmospheric dispersion model of CSA N288.1 with site-specific data

    CERN Document Server

    Chouhan, S L

    2001-01-01

    The atmospheric dispersion component of CSA Standard N288. 1, which provides guidelines for calculating derived release limits, has been tested. Long-term average concentrations of tritium in air were predicted using site-specific release rates and meteorological data and compared with measured concentrations at 43 monitoring sites at all CANDU stations in Canada. The predictions correlate well with the observations but were found to be conservative, overestimating by about 50% on average. The model overpredicted 84% of the time, with the highest prediction lying a factor of 5.5 above the corresponding observation. The model underpredicted the remaining 16% of the time, with the lowest prediction about one-half of the corresponding measurement. Possible explanations for this bias are discussed but no single reason appears capable of accounting for the discrepancy. Rather, the tendency to overprediction seems to result from the cumulative effects of a number of small conservatisms in the model. The model predi...

  8. Development of NEXRAD Wind Retrievals as Input to Atmospheric Dispersion Models

    Energy Technology Data Exchange (ETDEWEB)

    Fast, Jerome D.; Newsom, Rob K.; Allwine, K Jerry; Xu, Qin; Zhang, Pengfei; Copeland, Jeffrey H.; Sun, Jenny

    2007-03-06

    The objective of this study is to determine the feasibility that routinely collected data from the Doppler radars can appropriately be used in Atmospheric Dispersion Models (ADMs) for emergency response. We have evaluated the computational efficiency and accuracy of two variational mathematical techniques that derive the u- and v-components of the wind from radial velocities obtained from Doppler radars. A review of the scientific literature indicated that the techniques employ significantly different approaches in applying the variational techniques: 2-D Variational (2DVar), developed by NOAA¹s (National Oceanic and Atmospheric Administration's) National Severe Storms Laboratory (NSSL) and Variational Doppler Radar Analysis System (VDRAS), developed by the National Center for Atmospheric Research (NCAR). We designed a series of numerical experiments in which both models employed the same horizontal domain and resolution encompassing Oklahoma City for a two-week period during the summer of 2003 so that the computed wind retrievals could be fairly compared. Both models ran faster than real-time on a typical single dual-processor computer, indicating that they could be used to generate wind retrievals in near real-time. 2DVar executed ~2.5 times faster than VDRAS because of its simpler approach.

  9. Atmospheric Dispersion Modeling of the February 2014 Waste Isolation Pilot Plant Release

    Energy Technology Data Exchange (ETDEWEB)

    Nasstrom, John [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Piggott, Tom [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Simpson, Matthew [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Lobaugh, Megan [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Tai, Lydia [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Pobanz, Brenda [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Yu, Kristen [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-07-22

    This report presents the results of a simulation of the atmospheric dispersion and deposition of radioactivity released from the Waste Isolation Pilot Plant (WIPP) site in New Mexico in February 2014. These simulations were made by the National Atmospheric Release Advisory Center (NARAC) at Lawrence Livermore National Laboratory (LLNL), and supersede NARAC simulation results published in a previous WIPP report (WIPP, 2014). The results presented in this report use additional, more detailed data from WIPP on the specific radionuclides released, radioactivity release amounts and release times. Compared to the previous NARAC simulations, the new simulation results in this report are based on more detailed modeling of the winds, turbulence, and particle dry deposition. In addition, the initial plume rise from the exhaust vent was considered in the new simulations, but not in the previous NARAC simulations. The new model results show some small differences compared to previous results, but do not change the conclusions in the WIPP (2014) report. Presented are the data and assumptions used in these model simulations, as well as the model-predicted dose and deposition on and near the WIPP site. A comparison of predicted and measured radionuclide-specific air concentrations is also presented.

  10. Testing the atmospheric dispersion model of CSA N288.1 with site-specific data

    Energy Technology Data Exchange (ETDEWEB)

    Chouhan, S.L.; Davis, P.A

    2001-01-01

    The atmospheric dispersion component of CSA Standard N288. 1, which provides guidelines for calculating derived release limits, has been tested. Long-term average concentrations of tritium in air were predicted using site-specific release rates and meteorological data and compared with measured concentrations at 43 monitoring sites at all CANDU stations in Canada. The predictions correlate well with the observations but were found to be conservative, overestimating by about 50% on average. The model overpredicted 84% of the time, with the highest prediction lying a factor of 5.5 above the corresponding observation. The model underpredicted the remaining 16% of the time, with the lowest prediction about one-half of the corresponding measurement. Possible explanations for this bias are discussed but no single reason appears capable of accounting for the discrepancy. Rather, the tendency to overprediction seems to result from the cumulative effects of a number of small conservatisms in the model. The model predictions were slightly better when site-specific meteorological data were used in the calculations in place of the default data of N288.1. Some large discrepancies between predictions and observations at specific monitoring sites suggest that it is the measurements rather than the model that are at fault. The testing has therefore provided a check on the observations as well as on the model. Recommendations on model use and data collection are made to improve the level of agreement between predictions and observations in the future. (author)

  11. Accidental benzene release risk assessment in an urban area using an atmospheric dispersion model

    Science.gov (United States)

    Truong, Son C. H.; Lee, Myong-In; Kim, Ganghan; Kim, Dongmin; Park, Jong-Hwa; Choi, Sung-Deuk; Cho, Gi-Hyoug

    2016-11-01

    This study applied the American Meteorological Society and Environmental Protection Agency Regulatory Model (AERMOD) to assess the risk caused by an accidental release and dispersion of the toxic chemical benzene in the vicinity of a highly populated urban area. The modeling domain encompasses the Korean megacity of Ulsan, which includes two national industrial complexes and is characterized by a complex coastal terrain. Multiple AERMOD simulations were conducted for an assumed emission scenario using background wind data from August between 2009 and 2013. The series of experiments produced the spatial accident probability patterns for different concentration levels during daytime and nighttime scenarios based on the corresponding dominant wind patterns. This study further quantifies the potential accident risk based on the number of affected individuals by combining the accident probability with the indoor and outdoor population estimates. The chemical gas dispersion characteristics depend on various local meteorological conditions, such as the land-sea breeze direction, which alternates between daytime and nighttime, and the atmospheric stability. The results reveal that benzene dispersion affects a much larger area during the nighttime owing to the presence of a nocturnal stable boundary layer with significant temperature stratification. The affected area is smaller during the daytime owing to decreased stability and enhanced vertical mixing in the boundary layer. The results include a high degree of uncertainty during the nighttime owing to weak wind speeds and the lack of a prevailing wind direction, which impact the vulnerable area. However, vulnerable areas are more effectively identified during the daytime, when more consistent meteorological conditions exist. However, the potential risk becomes much lower during the nighttime owing to a substantial reduction of the outdoor population.

  12. Emulation and Sobol' sensitivity analysis of an atmospheric dispersion model applied to the Fukushima nuclear accident

    Science.gov (United States)

    Girard, Sylvain; Mallet, Vivien; Korsakissok, Irène; Mathieu, Anne

    2016-04-01

    Simulations of the atmospheric dispersion of radionuclides involve large uncertainties originating from the limited knowledge of meteorological input data, composition, amount and timing of emissions, and some model parameters. The estimation of these uncertainties is an essential complement to modeling for decision making in case of an accidental release. We have studied the relative influence of a set of uncertain inputs on several outputs from the Eulerian model Polyphemus/Polair3D on the Fukushima case. We chose to use the variance-based sensitivity analysis method of Sobol'. This method requires a large number of model evaluations which was not achievable directly due to the high computational cost of Polyphemus/Polair3D. To circumvent this issue, we built a mathematical approximation of the model using Gaussian process emulation. We observed that aggregated outputs are mainly driven by the amount of emitted radionuclides, while local outputs are mostly sensitive to wind perturbations. The release height is notably influential, but only in the vicinity of the source. Finally, averaging either spatially or temporally tends to cancel out interactions between uncertain inputs.

  13. Methodology for risk analysis based on atmospheric dispersion modelling from nuclear risk sites

    Science.gov (United States)

    Baklanov, A.; Mahura, A.; Sørensen, J. H.; Rigina, O.

    2003-04-01

    The main purpose of this multidisciplinary study is to develop a methodology for complex nuclear risk and vulnerability assessment, and to test it on example of estimation of nuclear risk to the population in the Nordic countries in case of a severe accident at a nuclear risk site (NRS). The main focus of the paper is the methodology for the evaluation of the atmospheric transport and deposition of radioactive pollutants from NRSs. The method developed for this evaluation is derived from a probabilistic point of view. The main question we are trying to answer is: What is the probability for radionuclide atmospheric transport and impact to different neighbouring regions and countries in case of an accident at an NPP? To answer this question we applied a number of different tools: (i) Trajectory Modelling - to calculate multiyear forward trajectories originating over the locations of selected risk sites; (ii) Dispersion Modelling - for long-term simulation and case studies of radionuclide transport from hypothetical accidental releases at NRSs; (iii) Cluster Analysis - to identify atmospheric transport pathways from NRSs; (iv) Probability Fields Analysis - to construct annual, monthly, and seasonal NRS impact indicators to identify the most impacted geographical regions; (v) Specific Case Studies - to estimate consequences for the environment and the populations after a hypothetical accident; (vi) Vulnerability Evaluation to Radioactive Deposition - to describe its persistence in the ecosystems with a focus to the transfer of certain radionuclides into the food chains of key importance for the intake and exposure for a whole population and for certain population groups; (vii) Risk Evaluation and Mapping - to analyse socio-economical consequences for different geographical areas and various population groups taking into account social-geophysical factors and probabilities, and using demographic databases based on GIS analysis.

  14. The model SIRANE for atmospheric urban pollutant dispersion; part I, presentation of the model

    Science.gov (United States)

    Soulhac, Lionel; Salizzoni, Pietro; Cierco, F.-X.; Perkins, Richard

    2011-12-01

    In order to control and manage urban air quality, public authorities require an integrated approach that incorporates direct measurements and modelling of mean pollutant concentrations. These have to be performed by means of operational modelling tools, that simulate the transport of pollutants within and above the urban canopy over a large number of streets. The operational models must be able to assess rapidly a large variety of situations and with limited computing resources. SIRANE is an operational urban dispersion model based on a simplified description of the urban geometry that adopts parametric relations for the pollutant transfer phenomena within and out of the urban canopy. The streets in a city district are modelled as a network of connected street segments. The flow within each street is driven by the component of the external wind parallel to the street, and the pollutant is assumed to be uniformly mixed within the street. The model contains three main mechanisms for transport in and out of a street: advection along the street axis, diffusion across the interface between the street and the overlying air flow and exchanges with other streets at street intersections. The dispersion of pollutants advected or diffused out of the streets is taken into account using a Gaussian plume model, with the standard deviations σ y and σ z parameterised by the similarity theory. The input data for the final model are the urban geometry, the meteorological parameters, the background concentration of pollutants advected into the model domain by the wind and the emissions within each street in the network.

  15. Ammonia emissions from an anaerobic digestion plant estimated using atmospheric measurements and dispersion modelling.

    Science.gov (United States)

    Bell, Michael W; Tang, Y Sim; Dragosits, Ulrike; Flechard, Chris R; Ward, Paul; Braban, Christine F

    2016-10-01

    Anaerobic digestion (AD) is becoming increasingly implemented within organic waste treatment operations. The storage and processing of large volumes of organic wastes through AD has been identified as a significant source of ammonia (NH3) emissions, however the totality of ammonia emissions from an AD plant have not been previously quantified. The emissions from an AD plant processing food waste were estimated through integrating ambient NH3 concentration measurements, atmospheric dispersion modelling, and comparison with published emission factors (EFs). Two dispersion models (ADMS and a backwards Lagrangian stochastic (bLS) model) were applied to calculate emission estimates. The bLS model (WindTrax) was used to back-calculate a total (top-down) emission rate for the AD plant from a point of continuous NH3 measurement downwind from the plant. The back-calculated emission rates were then input to the ADMS forward dispersion model to make predictions of air NH3 concentrations around the site, and evaluated against weekly passive sampler NH3 measurements. As an alternative approach emission rates from individual sources within the plant were initially estimated by applying literature EFs to the available site parameters concerning the chemical composition of waste materials, room air concentrations, ventilation rates, etc. The individual emission rates were input to ADMS and later tuned by fitting the simulated ambient concentrations to the observed (passive sampler) concentration field, which gave an excellent match to measurements after an iterative process. The total emission from the AD plant thus estimated by a bottom-up approach was 16.8±1.8mgs(-1), which was significantly higher than the back-calculated top-down estimate (7.4±0.78mgs(-1)). The bottom-up approach offered a more realistic treatment of the source distribution within the plant area, while the complexity of the site was not ideally suited to the bLS method, thus the bottom-up method is believed

  16. Analysis of uncertainties caused by the atmospheric dispersion model in accident consequence assessments with UFOMOD

    International Nuclear Information System (INIS)

    Various techniques available for uncertainty analysis of large computer models are applied, described and selected as most appropriate for analyzing the uncertainty in the predictions of accident consequence assessments. The investigation refers to the atmospheric dispersion and deposition submodel (straight-line Gaussian plume model) of UFOMOD, whose most important input variables and parameters are linked with probability distributions derived from expert judgement. Uncertainty bands show how much variability exists, sensitivity measures determine what causes this variability in consequences. Results are presented as confidence bounds of complementary cumulative frequency distributions (CCFDs) of activity concentrations, organ doses and health effects, partially as a function of distance from the site. In addition the ranked influence of the uncertain parameters on the different consequence types is shown. For the estimation of confidence bounds it was sufficient to choose a model parameter sample size of n (n=59) equal to 1.5 times the number of uncertain model parameters. Different samples or an increase of sample size did not change the 5%-95% - confidence bands. To get statistically stable results of the sensitivity analysis, larger sample sizes are needed (n=100, 200). Random or Latin-hypercube sampling schemes as tools for uncertainty and sensitivity analyses led to comparable results. (orig.)

  17. Dutch distribution zones of stable iodine tablets based on atmospheric dispersion modelling of accidental releases from nuclear power plants.

    NARCIS (Netherlands)

    Kok-Palma, Y.S.; Leenders, M.; Meulenbelt, J.

    2010-01-01

    Rapid administration of stable iodine is essential for the saturation and subsequent protection of the thyroid gland against the potential harm caused by radioiodines. This paper proposes the Dutch risk analysis that uses an atmospheric dispersion model to calculate the size of the zones around nucl

  18. Detailed source term estimation of the atmospheric release for the Fukushima Daiichi Nuclear Power Station accident by coupling simulations of an atmospheric dispersion model with an improved deposition scheme and oceanic dispersion model

    Science.gov (United States)

    Katata, G.; Chino, M.; Kobayashi, T.; Terada, H.; Ota, M.; Nagai, H.; Kajino, M.; Draxler, R.; Hort, M. C.; Malo, A.; Torii, T.; Sanada, Y.

    2015-01-01

    Temporal variations in the amount of radionuclides released into the atmosphere during the Fukushima Daiichi Nuclear Power Station (FNPS1) accident and their atmospheric and marine dispersion are essential to evaluate the environmental impacts and resultant radiological doses to the public. In this paper, we estimate the detailed atmospheric releases during the accident using a reverse estimation method which calculates the release rates of radionuclides by comparing measurements of air concentration of a radionuclide or its dose rate in the environment with the ones calculated by atmospheric and oceanic transport, dispersion and deposition models. The atmospheric and oceanic models used are WSPEEDI-II (Worldwide version of System for Prediction of Environmental Emergency Dose Information) and SEA-GEARN-FDM (Finite difference oceanic dispersion model), both developed by the authors. A sophisticated deposition scheme, which deals with dry and fog-water depositions, cloud condensation nuclei (CCN) activation, and subsequent wet scavenging due to mixed-phase cloud microphysics (in-cloud scavenging) for radioactive iodine gas (I2 and CH3I) and other particles (CsI, Cs, and Te), was incorporated into WSPEEDI-II to improve the surface deposition calculations. The results revealed that the major releases of radionuclides due to the FNPS1 accident occurred in the following periods during March 2011: the afternoon of 12 March due to the wet venting and hydrogen explosion at Unit 1, midnight of 14 March when the SRV (safety relief valve) was opened three times at Unit 2, the morning and night of 15 March, and the morning of 16 March. According to the simulation results, the highest radioactive contamination areas around FNPS1 were created from 15 to 16 March by complicated interactions among rainfall, plume movements, and the temporal variation of release rates. The simulation by WSPEEDI-II using the new source term reproduced the local and regional patterns of cumulative

  19. Development of local-scale high-resolution atmospheric dispersion model using large-eddy simulation. Part 4. Turbulent flows and plume dispersion in an actual urban area

    International Nuclear Information System (INIS)

    We have developed a local-scale high-resolution atmospheric dispersion model using large-eddy simulation (LOHDIM-LES) to assess the safety at nuclear facilities and to respond to emergency situations resulting from accidental or deliberate releases of radioactive materials (e.g., a terrorist attack in an urban area). In Part 1, the unsteady behavior of a plume dispersing over a flat terrain was successfully simulated. In Parts 2 and 3, LESs of turbulent flows and plume dispersion around an isolated building and in building arrays with different obstacle densities were performed, which showed the basic performance comparable to wind tunnel experimental technique. In this study, we apply the LES model to turbulent flows and plume dispersion in an actual urban area. Although some of the turbulence and dispersion characteristics are quantitatively different from the wind tunnel experimental data, the distribution patterns are generally similar to those of the experiments. It is concluded that our LES model simulates reasonably the unsteady behavior of turbulent flows and plume dispersion even for complex heterogeneous urban areas. (author)

  20. krX system: multi-scale modelling of atmospheric dispersion and consequences assessments for radiological emergencies

    International Nuclear Information System (INIS)

    Full text: In case of a nuclear emergency, the krX system simulates the plume behaviour and assesses consequences of these releases. The krX system consists of a suite of meteorological and atmospheric dispersion models coupled with a consequences model. The meteorological module is essentially the atmospheric model, MM5. For the local scale, the atmospheric dispersion modelling is using the multi-module pX model. PX will provide 3 dispersion models: a pure Gaussian Puff, a Lagrangian model and a mixed Eulerian-Lagrangian one. For the regional to continental scale, the krX system uses a special adaptation of the POLAIR3D/POLYPHEMUS model. POLAIR3D is a chemistry-transport model flexible enough to handle a wide range of applications from passive tracers to complex chemical mechanisms. POLYPHEMUS is a full modelling system for air quality. It is designed to yield up-to-date simulations in a reliable framework: aerosols, data assimilation, ensemble forecast and daily forecasts. We will present the krX system and some comparisons with experimental study. Finally, future developments will be discussed. (author)

  1. Accuracy of Gaussian plume dispersion model predictions as a function of three atmospheric stability classification calculations

    International Nuclear Information System (INIS)

    Air concentration measurements made at Hanford, WA, for short-term surface-level release of flourescein particles are compared with predicted values derived from curves in Turner's Workbook of Atmospheric Dispersion Estimates. Predictions were determined from these curves based on three different sets of criteria to classify atmospheric stability: namely two different sets of vertical temperature gradient measurements, deltaT/deltaZ, and the standard deviation of the wind direction, σsub(theta), at a height of 1.5m. Results indicate that predictions based on the σsub(theta) method of determining atmospheric stability are more accurate than those based on either set of deltaT/deltaZ measurements considered. However, there was a tendency for all three methods to overpredict tracer concentrations in air. These results have direct application to activities concerned with assessing the impact of radionuclides released to the environment. (author)

  2. Applicability of a high-resolution meso-scale meteorological model to a near-field-scale atmospheric dispersion problem

    International Nuclear Information System (INIS)

    This study examines the feasibility of numerical simulations using a meso-scale meteorological model (NuWFAS: Numerical Weather Forecasting and Analysis System) for a near-field-scale atmospheric dispersion problem. A series of observation data from a field tracer experiment was used for the validation of the model. In the experiments, the tracer was released from a tower at a height of 95 m. The receptors were located on the arc lines with distances from the source of 400, 750, 1500, and 3000 m. The numerical simulations were implemented with two different minimum spatial resolutions of 100 m and 300 m. The meteorological fields were reproduced with a reasonable accuracy, showing the less dependency on the mesh sizes of the simulation. The dispersion fields were also less dependent on the spatial resolutions except for the stable atmospheric conditions. In stable conditions, the smaller spatial resolution leads to the higher surface concentrations due to the larger turbulent diffusions. In most cases, the predicted surface concentrations agreed with the observation within the factor of ten. However, the simulation tends to underestimate the surface concentrations in stable conditions, whereas it overestimates in unstable conditions. Our study revealed that the limitation of the model in estimating the turbulent diffusion coefficients for thermally stratified conditions is the one cause of these trends. The current model underestimates the influences of atmospheric stability, which is one of the most important factors for the near-field-scale atmospheric dispersion. (author)

  3. UFOMOD - atmospheric dispersion and deposition

    International Nuclear Information System (INIS)

    The report gives an introduction into the modelling of atmospheric dispersion and deposition which has been implemented in the new program system UFOMOD for assessing the consequences after nuclear accidents. According to the new structure of UFOMOD, different trajectory models with ranges of validity near to the site and at far distances are applied. Emphasis is laid on the description of the segmented plume model MUSEMET and its affilated submodels, being the removal of activity from the cloud by dry and wet deposition, and special effects like plume rise and the behaviour of plumes released into building wakes. In addition, the evaluation of γ-dose correction factors to take account of the finite extent of the radioactive plume in the near range (up to about 20 km) are described. Only brief introductions are given into the principles of the other models available: the puff model RIMPUFF, the long-range puff model MESOS, and the special straight-line Gaussian model ISOLA which are used if low-level long-duration releases are considered. To define starting times of weather sequences and the probabilities of occurrence of these sequences, it is convenient to perform stratified sampling. Therefore, the preprocessing program package METSAM has been developed to perform for generic ACAs a random sampling of weather sequences out off a population of classified weather conditions. The sampling procedure and a detailed input/output (I/O) description is presented and an additional appendix, respectively. A general overview on the I/O structure of MUSEMET as well as a brief user guide to run the KfK version of the MESOS code are also given in the appendix. (orig.)

  4. An analytical model for dispersion of material in the atmospheric planetary boundary layer in presence of precipitation

    International Nuclear Information System (INIS)

    An analytical model for the dispersion of particulates and finely divided material released into the atmosphere near the ground is presented. The possible precipitation when the particles are dense enough and large enough to have deposition velocity, is taken into consideration. The model is derived analytically in the mixing layer or Ekman boundary layer where the mixing process is a direct consequence of turbulent and convective motions generated in the boundary layer. (author)

  5. ATMOSPHERIC DISPERSION OF RADIOACTIVE DEBRIS RELEASED IN CASE OF NUCLEAR EXPLOSION USING THE NORWEGIAN SNAP MODEL

    OpenAIRE

    Bartnicki, Jerzy; Saltbones, Jørgen

    2008-01-01

    Abstract: Severe Nuclear Accident Program (SNAP) has been developed at the Norwegian Meteorological Institute (met.no) for modelling dispersion of radioactive debris in case of nuclear accidents. The model has been tested based on the data available from the Chernobyl accident as well as from the ETEX experiments. The main user of model results is the Norwegian Radiation Protection Authority (NRPA) which is responsible for calculating doses in case of a real accident. The model is fu...

  6. Improved Meteorological Input for Atmospheric Release Decision support Systems and an Integrated LES Modeling System for Atmospheric Dispersion of Toxic Agents: Homeland Security Applications

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, E; Simpson, M; Larsen, S; Gash, J; Aluzzi, F; Lundquist, J; Sugiyama, G

    2010-04-26

    When hazardous material is accidently or intentionally released into the atmosphere, emergency response organizations look to decision support systems (DSSs) to translate contaminant information provided by atmospheric models into effective decisions to protect the public and emergency responders and to mitigate subsequent consequences. The Department of Homeland Security (DHS)-led Interagency Modeling and Atmospheric Assessment Center (IMAAC) is one of the primary DSSs utilized by emergency management organizations. IMAAC is responsible for providing 'a single piont for the coordination and dissemination of Federal dispersion modeling and hazard prediction products that represent the Federal position' during actual or potential incidents under the National Response Plan. The Department of Energy's (DOE) National Atmospheric Release Advisory Center (NARAC), locatec at the Lawrence Livermore National Laboratory (LLNL), serves as the primary operations center of the IMAAC. A key component of atmospheric release decision support systems is meteorological information - models and data of winds, turbulence, and other atmospheric boundary-layer parameters. The accuracy of contaminant predictions is strongly dependent on the quality of this information. Therefore, the effectiveness of DSSs can be enhanced by improving the meteorological options available to drive atmospheric transport and fate models. The overall goal of this project was to develop and evaluate new meteorological modeling capabilities for DSSs based on the use of NASA Earth-science data sets in order to enhance the atmospheric-hazard information provided to emergency managers and responders. The final report describes the LLNL contributions to this multi-institutional effort. LLNL developed an approach to utilize NCAR meteorological predictions using NASA MODIS data for the New York City (NYC) region and demonstrated the potential impact of the use of different data sources and data

  7. Atmospheric Chemistry in Existing Air Atmospheric Dispersion Models and Their Applications: Trends, Advances and Future in Urban Areas in Ontario, Canada and in Other Areas of the World

    Directory of Open Access Journals (Sweden)

    Barbara Laskarzewska

    2009-03-01

    Full Text Available Air quality is a major concern for the public. Therefore, the reliability in modeling and predicting the air quality accurately is of a major interest. This study reviews existing atmospheric dispersion models, specifically, the Gaussian Plume models and their capabilities to handle the atmospheric chemistry of nitrogen oxides (NOx and sulfur dioxides (SO2. It also includes a review of wet deposition in the form of in-cloud, below cloud, and snow scavenging. Existing dispersion models are investigated to assess their capability of handling atmospheric chemistry, specifically in the context of NOx and SO2 substances and their applications to urban areas. A number of previous studies have been conducted where Gaussian dispersion model was applied to major cities around the world such as London, Helsinki, Kanto, and Prague, to predict ground level concentrations of NOx and SO2. These studies demonstrated a good agreement between the modeled and observed ground level concentrations of NOx and SO2. Toronto, Ontario, Canada is also a heavily populated urban area where a dispersion model could be applied to evaluate ground level concentrations of various contaminants to better understand the air quality. This paper also includes a preliminary study of road emissions for a segment of the city of Toronto and its busy streets during morning and afternoon rush hours. The results of the modeling are compared to the observed data. The small scale test of dispersion of NO2 in the city of Toronto was utilized for the local hourly meteorological data and traffic emissions. The predicted ground level concentrations were compared to Air Quality Index (AQI data and showed a good agreement. Another improvement addressed here is a discussion on various wet deposition such as in cloud, below cloud, and snow.

  8. SPRAYTRAN USER'S GUIDE: A GIS-BASED ATMOSPHERIC SPRAY DROPLET DISPERSION MODELING SYSTEM

    Science.gov (United States)

    The offsite drift of pesticide from spray operations is an ongoing source of concern. The SPRAY TRANsport (SPRAYTRAN) system, documented in this report, incorporates the near-field spray application model, AGDISP, into a meso-scale atmospheric transport model. The AGDISP model ...

  9. Application of data assimilation to improve the forecasting capability of an atmospheric dispersion model for a radioactive plume

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, H.J. [Nuclear Environment Safety Research Center, Korea Atomic Energy Research Institute, 150, Dukjin-dong, Yuseong-gu, Daejeon 305-353 (Korea, Republic of)], E-mail: jeong1208@kaeri.re.kr; Han, M.H.; Hwang, W.T.; Kim, E.H. [Nuclear Environment Safety Research Center, Korea Atomic Energy Research Institute, 150, Dukjin-dong, Yuseong-gu, Daejeon 305-353 (Korea, Republic of)

    2008-05-15

    Modeling an atmospheric dispersion of a radioactive plume plays an influential role in assessing the environmental impacts caused by nuclear accidents. The performance of data assimilation techniques combined with Gaussian model outputs and measurements to improve forecasting abilities are investigated in this study. Tracer dispersion experiments are performed to produce field data by assuming a radiological emergency. Adaptive neuro-fuzzy inference system (ANFIS) and linear regression filter are considered to assimilate the Gaussian model outputs with measurements. ANFIS is trained so that the model outputs are likely to be more accurate for the experimental data. Linear regression filter is designed to assimilate measurements similar to the ANFIS. It is confirmed that ANFIS could be an appropriate method for an improvement of the forecasting capability of an atmospheric dispersion model in the case of a radiological emergency, judging from the higher correlation coefficients between the measured and the assimilated ones rather than a linear regression filter. This kind of data assimilation method could support a decision-making system when deciding on the best available countermeasures for public health from among emergency preparedness alternatives.

  10. Atmospheric and dispersion modeling in areas of highly complex terrain employing a four-dimensional data assimilation technique

    Energy Technology Data Exchange (ETDEWEB)

    Fast, J.D.; O`Steen, B.L.

    1994-12-31

    The results of this study indicate that the current data assimilation technique can have a positive impact on the mesoscale flow fields; however, care must be taken in its application to grids of relatively fine horizontal resolution. Continuous FDDA is a useful tool in producing high-resolution mesoscale analysis fields that can be used to (1) create a better initial conditions for mesoscale atmospheric models and (2) drive transport models for dispersion studies. While RAMS is capable of predicting the qualitative flow during this evening, additional experiments need to be performed to improve the prognostic forecasts made by RAMS and refine the FDDA procedure so that the overall errors are reduced even further. Despite the fact that a great deal of computational time is necessary in executing RAMS and LPDM in the configuration employed in this study, recent advances in workstations is making applications such as this more practical. As the speed of these machines increase in the next few years, it will become feasible to employ prognostic, three-dimensional mesoscale/transport models to routinely predict atmospheric dispersion of pollutants, even to highly complex terrain. For example, the version of RAMS in this study could be run in a ``nowcasting`` model that would continually assimilate local and regional observations as soon as they become available. The atmospheric physics in the model would be used to determine the wind field where no observations are available. The three-dimensional flow fields could be used as dynamic initial conditions for a model forecast. The output from this type of modeling system will have to be compared to existing diagnostic, mass-consistent models to determine whether the wind field and dispersion forecasts are significantly improved.

  11. Atmospheric dispersion modeling and radiological safety analysis for a hypothetical accident of Ghana Research Reactor-1 (GHARR-1)

    International Nuclear Information System (INIS)

    Highlights: • An atmospheric dispersion model for a hypothetical accident of Ghana Research Reactor-1 (GHARR-1) was developed. • Radiological safety analysis after the postulated accident was also carried out. • The MCNPX and HotSpot codes were used to achieve the objectives of our study. • All the values of effective dose obtained following the accident were far below the regulatory limits. - Abstract: Atmospheric dispersion modeling and radiological safety analysis were performed for a postulated accident scenario of the generic Low-Enriched Uranium (LEU) Ghana Research Reactor-1 (GHARR-1) core. The source term was generated from an inventory of peak radioisotope activities released by using the isotope generation code MCNPX. The health physics code, HotSpot, was used to perform the atmospheric transport modeling which was then applied to calculate the total effective dose and how it would be distributed to human organs as a function of distance downwind. All accident scenarios were selected from the GHARR-1 Safety Analysis Report (SAR), assuming that the activities were released to the atmosphere after a design basis accident. The adopted methodology was the use of predominant site-specific meteorological data and dispersion modeling theories to analyze the incident of a hypothetical release to the environment of some selected radionuclides from the site and evaluate to what extent such a release may have radiological effects on the public. The results indicate that all the values of Effective dose obtained, with the maximum of 2.62 × 10−2 mSv at 110 m from the reactor, were far below the regulatory limits, making the use of the reactor safe, even in the event of severe accident scenario

  12. Distributed emergency response system to model dispersion and deposition of atmospheric releases

    International Nuclear Information System (INIS)

    Aging hardware and software and increasing commitments by the Departments of Energy and Defense have led us to develop a new, expanded system to replace the existing Atmospheric Release Advisory Capability (ARAC) system. This distributed, computer-based, emergency response system is used by state and federal agencies to assess the environmental health hazards resulting from an accidental release of radioactive material into the atmosphere. Like its predecessor, the expanded system uses local meteorology (e.g., wind speed and wind direction), as well as terrain information, to simulate the transport and dispersion of the airborne material. The system also calculates deposition and dose and displays them graphically over base maps of the local geography for use by on-site authorities. This paper discusses the limitations of the existing ARAC system. It also discusses the components and functionality of the new system, the technical difficulties encountered and resolved in its design and implementation, and the software methodologies and tools employed in its development

  13. A study on atmospheric dispersion around Kalpakkam coastal site using a non-hydrostatic model and comparison with field data

    International Nuclear Information System (INIS)

    Study of the sea breeze characteristics and Thermal Internal Boundary Layer (TIBL) is very important to understand the dispersion characteristics of air pollutants near coastal area. In the present paper, dispersion characteristics near Kalpakkam coastal area are studied and discussed by simulating sea breeze characteristics and TIBL using a non-hydrostatic mesoscale model in its two dimensional form. The model is run with surface physics, simplified radiation physics and turbulent kinetic energy (TKE) closure scheme for diffusion. A joint meteorological field experiment was carried out by IITM-Pune at Kalpakkam by deploying state of art sensors and tether balloon systems for observing the height profiles of meteorological parameters. The data taken from the field experiment is used here to compare the simulations. Results shows that the onset of sea breeze is one hour before as observed from the field experiment. Slight difference is also seen in wind speed and temperature. Spatial variation of the dispersion pattern could be understood from the simulated TKE profile. From the study, it is shown that the model gives only a over all picture of the real scenario and successful simulations require the inclusion of more atmospheric dynamics such as microphysics, cumulus parameterization and atmospheric radiation. (author)

  14. A computer programmed model for calculation of fall and dispersion of particles in the atmosphere

    International Nuclear Information System (INIS)

    An atmospheric model has been designed and developed to provide estimates of air concentrations or ground deposit densities of particles released in the atmosphere up to 90-km altitude. Particle density and diameter may range from 1 to 10 g/cm3 and about 3 to 300μ, respectively, for given instantaneous point or line sources. The particle cloud is allowed to move horizontally in accordance with analytically simulated winds and to fall at terminal velocity plus vertical air velocity. Small-scale cloud growth rate is specified empirically at values based on past instantaneous tracer experiments while large-scale growth results from trajectory subdivision and divergence of new particle trajectories. Some specific computer runs at Sandia were done to assess hazards resulting from possible rocket abort situations and atmospheric re-entry from improper orbits of isotopic or reactor power supplies. The results have been compared with other modes of estimation derived from simpler models of world-wide contaminant spread. While existing data are insufficient for full verification, it is felt that the present model is one of the most comprehensive and realistic available. (author)

  15. Some Observational and Modeling Studies of the Atmospheric Boundary Layer at Mississippi Gulf Coast for Air Pollution Dispersion Assessment

    Directory of Open Access Journals (Sweden)

    Anjaneyulu Yerramilli

    2008-12-01

    Full Text Available Coastal atmospheric conditions widely vary from those over inland due to the land-sea interface, temperature contrast and the consequent development of local circulations. In this study a field meteorological experiment was conducted to measure vertical structure of boundary layer during the period 25-29 June, 2007 at three locations Seabee base, Harrison and Wiggins sites in the Mississippi coast. A GPS Sonde along with slow ascent helium balloon and automated weather stations equipped with slow and fast response sensors were used in the experiment. GPS sonde were launched at three specific times (0700 LT, 1300 LT and 1800 LT during the experiment days. The observations indicate shallow boundary layer near the coast which gradually develops inland. The weather research and forecasting (WRF meso-scale atmospheric model and a Lagrangian particle dispersion model (HYSPLIT are used to simulate the lower atmospheric flow and dispersion in a range of 100 km from the coast for 28-30 June, 2007. The simulated meteorological parameters were compared with the experimental observations. The meso-scale model results show significant temporal and spatial variations in the meteorological fields as a result of development of sea breeze flow, its coupling with the large scale flow field and the ensuing alteration in the mixing depth across the coast. Simulated ground-level concentrations of SO2 from four elevated point sources located along the coast indicate diurnal variation and impact of the local sea-land breeze on the direction of the plume. Model concentration levels were highest during the stable morning condition and during the sea-breeze time in the afternoon. The highest concentrations were found up to 40 km inland during sea breeze time. The study illustrates the application of field meteorological observations for the validation of WRF which is coupled to HYSPLIT for dispersion assessment in the coastal region.

  16. VALDRIFT 1.0: A valley atmospheric dispersion model with deposition

    Energy Technology Data Exchange (ETDEWEB)

    Allwine, K.J.; Bian, X.; Whiteman, C.D.

    1995-05-01

    VALDRIFT version 1.0 is an atmospheric transport and diffusion model for use in well-defined mountain valleys. It is designed to determine the extent of ddft from aedal pesticide spraying activities, but can also be applied to estimate the transport and diffusion of various air pollutants in valleys. The model is phenomenological -- that is, the dominant meteorological processes goveming the behavior of the valley atmosphere are formulated explicitly in the model, albeit in a highly parameterized fashion. The key meteorological processes treated are: (1) nonsteady and nonhomogeneous along-valley winds and turbulent diffusivities, (2) convective boundary layer growth, (3) inversion descent, (4) noctumal temperature inversion breakup, and (5) subsidence. The model is applicable under relatively cloud-free, undisturbed synoptic conditions and is configured to operate through one diumal cycle for a single valley. The inputs required are the valley topographical characteristics, pesticide release rate as a function of time and space, along-valley wind speed as a function of time and space, temperature inversion characteristics at sunrise, and sensible heat flux as a function of time following sunrise. Default values are provided for certain inputs in the absence of detailed observations. The outputs are three-dimensional air concentration and ground-level deposition fields as a function of time.

  17. Atmospheric Transport Modeling with 3D Lagrangian Dispersion Codes Compared with SF6 Tracer Experiments at Regional Scale

    International Nuclear Information System (INIS)

    The results of four gas tracer experiments of atmospheric dispersion on a regional scale are used for the benchmarking of two atmospheric dispersion modeling codes, MINERVE-SPRAY (CEA), and NOSTRADAMUS (IBRAE). The main topic of this comparison is to estimate the Lagrangian code capability to predict the radionuclide atmospheric transfer on a large field, in the case of risk assessment of nuclear power plant for example. For the four experiments, the results of calculations show a rather good agreement between the two codes, and the order of magnitude of the concentrations measured on the soil is predicted. Simulation is best for sampling points located ten kilometers from the source, while we note a divergence for more distant points results (difference in concentrations by a factor 2 to 5). This divergence may be explained by the fact that, for these four experiments, only one weather station (near the point source) was used on a field of 10000 km2, generating the simulation of a uniform wind field throughout the calculation domain.

  18. Atmospheric Transport Modeling with 3D Lagrangian Dispersion Codes Compared with SF6 Tracer Experiments at Regional Scale

    Directory of Open Access Journals (Sweden)

    François Van Dorpe

    2007-01-01

    Full Text Available The results of four gas tracer experiments of atmospheric dispersion on a regional scale are used for the benchmarking of two atmospheric dispersion modeling codes, MINERVE-SPRAY (CEA, and NOSTRADAMUS (IBRAE. The main topic of this comparison is to estimate the Lagrangian code capability to predict the radionuclide atmospheric transfer on a large field, in the case of risk assessment of nuclear power plant for example. For the four experiments, the results of calculations show a rather good agreement between the two codes, and the order of magnitude of the concentrations measured on the soil is predicted. Simulation is best for sampling points located ten kilometers from the source, while we note a divergence for more distant points results (difference in concentrations by a factor 2 to 5. This divergence may be explained by the fact that, for these four experiments, only one weather station (near the point source was used on a field of 10 000 km2, generating the simulation of a uniform wind field throughout the calculation domain.

  19. Atmospheric dispersion modeling and radiological safety analysis for a hypothetical accident of Ghana Research Reactor -1 (GHARR-1)

    International Nuclear Information System (INIS)

    This work presents the environmental impact analysis of some selected radionuclides released from the Ghana Research Reactor- 1 (GHARR-1) after a hypothetical postulated accidents scenario. The source term was identified and generated from an inventory of radioisotopes released during the accident. Atmospheric transport model was then applied to calculate the total effective dose and how it would be distributed to different organs of the human body as a function of distance downwind. All accident scenarios were selected from GHARR-1 Safety Analysis Report. After the source term was identified the MCNPX code was used to perform the core burnup/depletion analysis. The assumption was made that the activities were released to the atmosphere under a horse design basis accident scenario. The gaussian dose calculation method was applied, coded in Hotspot, a Healthy Physics computer code. This served as the computational tool to perform the atmospheric dispersion modeling and was used to calculate radionuclide concentration at downwind location. Based upon predominant meteorological conditions at the site, the adopted strategy was to use site-specific meteorological data and dispersion modeling to analyze the hypothetical release to the environment of radionuclides and evaluate to what extent such a release may have radiological effects on the public. Final data were processed and presented as Total Effective Dose Equivalent as a function of time and distance of deposition. The results indicate that all the values of Effective dose obtained are far below the regulatory limits, making the use of the reactor safe, even in the case of worst accident scenario where all the fission products were released into the atmosphere. (au)

  20. Assessment of wind characteristics and atmospheric dispersion modeling of {sup 137}Cs on the Barakah NPP area in the USA

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong Kuk; Lee, Kun Jai; Yun, Jong IL [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Kim, Jae Chul; Belorid, Miloslav [Institute of Environmental Research, Chuncheon (Korea, Republic of); Beeley, Philip A. [Khalifa University of Science, Technology and Research, Dubai (Antigua and Barbuda)

    2014-08-15

    This paper presents the results of an analysis of wind characteristics and atmosphere dispersion modeling that are based on computational simulation and part of a preliminary study evaluating environmental radiation monitoring system (ERMS) positions within the Barakah nuclear power plant (BNPP). The return period of extreme wind speed was estimated using the Weibull distribution over the life time of the BNPP. In the annual meteorological modeling, the winds from the north and west accounted for more than 90 % of the wind directions. Seasonal effects were not represented. However, a discrepancy in the tendency between daytime and nighttime was observed. Six variations of cesium-137 ({sup 137}Cs) dispersion test were simulated under severe accident condition. The {sup 137}Cs dispersion was strongly influenced by the direction and speed of the main wind. A virtual receptor was set and calculated for observation of the {sup 137}Cs movement and accumulation. The results of the surface roughness effect demonstrated that the deposition of {sup 137}Cs was affected by surface condition. The results of these studies offer useful information for developing environmental radiation monitoring systems (ERMSs) for the BNPP and can be used to assess the environmental effects of new nuclear power plant.

  1. Detailed source term estimation of the atmospheric release for the Fukushima Daiichi Nuclear Power Station accident by coupling simulations of an atmospheric dispersion model with an improved deposition scheme and oceanic dispersion model

    OpenAIRE

    G. Katata; Chino, M; T. Kobayashi; Terada, H.; Ota, M; Nagai, H.; M. Kajino; Draxler, R; M. C. Hort; Malo, A.; Torii, T.; Y. Sanada

    2015-01-01

    Temporal variations in the amount of radionuclides released into the atmosphere during the Fukushima Daiichi Nuclear Power Station (FNPS1) accident and their atmospheric and marine dispersion are essential to evaluate the environmental impacts and resultant radiological doses to the public. In this paper, we estimate the detailed atmospheric releases during the accident using a reverse estimation method which calculates the release rates of radionuclides by comparing measure...

  2. A RECOMMENDED PASQUILL-GIFFORD STABILITY CLASSIFICATION METHOD FOR SAFETY BASIS ATMOSPHERIC DISPERSION MODELING AT SRS

    Energy Technology Data Exchange (ETDEWEB)

    Hunter, C.

    2012-03-28

    Several of the most common methods for estimating Pasquill-Gifford (PG) stability (turbulence) class were evaluated for use in modeling the radiological consequences of SRS accidental releases using the MELCOR Accident Consequence Code System, Ver. 2 (MACCS2). Evaluation criteria included: (1) the ability of the method to represent diffusion characteristics above a predominantly forested landscape at SRS, (2) suitability of the method to provide data consistent with the formulation of the MACCS2 model, and (3) the availability of onsite meteorological data to support implementation of the method The evaluation resulted in a recommendation that PG stability classification for regulatory applications at SRS should be based on measurements of the standard deviation of the vertical component of wind direction fluctuations, {sigma}{sub e}, collected from the 61-m level of the SRS meteorological towers, and processed in full accordance with EPA-454/R-99-005 (EPA, 2000). This approach provides a direct measurement that is fundamental to diffusion and captures explicitly the turbulence generated by both mechanical and buoyant forces over the characteristic surface (forested) of SRS. Furthermore, due to the potentially significant enhancement of horizontal fluctuations in wind direction from the occurrence of meander at night, the use of {sigma}{sub e} will ensure a reasonably conservative estimate of PG stability class for use in dispersion models that base diffusion calculations on a single value of PG stability class. Furthermore, meteorological data bases used as input for MACCS2 calculations should contain hourly data for five consecutive annual periods from the most recent 10 years.

  3. Dispersion of effluents in the atmosphere; Dispersion des effluents dans l`atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-12-31

    This conference day was organized by the `convection` section of the French association of thermal engineers with the support of the environment and energy mastery agency (ADEME). This book of proceedings contains 10 papers entitled: `physical modeling of atmospheric dispersion in wind tunnels. Some industrial examples`; `modeling of the noxious effects of a fire on the environment of an industrial site: importance of thermal engineering related hypotheses`; `atmospheric diffusion of a noxious cloud: fast evaluation method of safety areas around refrigerating installations that use ammonia`; `modeling of atmospheric flows in urban areas in order to study the dispersion of pollutants`; `use of a dispersion parameter to characterize the evolution of a diffusion process downstream of a linear source of passive contaminant placed inside a turbulent boundary layer`; `elements of reflexion around the development of an analytical methodology applied to the elaboration of measurement strategies of air quality in ambient and outdoor atmospheres around industrial sites`; `state-of-the-art about treatment techniques for VOC-rich gaseous effluents`; `characteristics of the time variation of the atmospheric pollution in the Paris region and visualization of its space distribution`; `mass-spectrometry for the measurement of atmospheric pollutants`; `volume variations in natural convection turbulence`. (J.S.)

  4. International comparison of computer codes for modelling the dispersion and transfer of tritium released to the atmosphere

    International Nuclear Information System (INIS)

    Computer codes for modelling the dispersion and transfer of tritium released to the atmosphere were compared. The codes originated from Canada, the United States, Sweden and Japan. The comparisons include acute and chronic emissions of tritiated water vapour or elemental tritium from a hypothetical nuclear facility. Individual and collective doses to the population within 100 km of the site were calculated. The discrepancies among the code predictions were about one order of magnitude for the HTO emissions but were significantly more varied for the HT emissions. Codes that did not account for HT to HTO conversion and cycling of tritium in the environment predicted doses that were several orders of magnitude less than codes that incorporate this feature into the model

  5. Detailed source term estimation of the atmospheric release for the Fukushima Daiichi Nuclear Power Station accident by coupling simulations of atmospheric dispersion model with improved deposition scheme and oceanic dispersion model

    Directory of Open Access Journals (Sweden)

    G. Katata

    2014-06-01

    Full Text Available Temporal variations in the amount of radionuclides released into the atmosphere during the Fukushima Dai-ichi Nuclear Power Station (FNPS1 accident and their atmospheric and marine dispersion are essential to evaluate the environmental impacts and resultant radiological doses to the public. In this paper, we estimate a detailed time trend of atmospheric releases during the accident by combining environmental monitoring data with atmospheric model simulations from WSPEEDI-II (Worldwide version of System for Prediction of Environmental Emergency Dose Information, and simulations from the oceanic dispersion model SEA-GEARN-FDM, both developed by the authors. A sophisticated deposition scheme, which deals with dry and fogwater depositions, cloud condensation nuclei (CCN activation and subsequent wet scavenging due to mixed-phase cloud microphysics (in-cloud scavenging for radioactive iodine gas (I2 and CH3I and other particles (CsI, Cs, and Te, was incorporated into WSPEEDI-II to improve the surface deposition calculations. The fallout to the ocean surface calculated by WSPEEDI-II was used as input data for the SEA-GEARN-FDM calculations. Reverse and inverse source-term estimation methods based on coupling the simulations from both models was adopted using air dose rates and concentrations, and sea surface concentrations. The results revealed that the major releases of radionuclides due to FNPS1 accident occurred in the following periods during March 2011: the afternoon of 12 March due to the wet venting and hydrogen explosion at Unit 1, the morning of 13 March after the venting event at Unit 3, midnight of 14 March when the SRV (Safely Relief Valve at Unit 2 was opened three times, the morning and night of 15 March, and the morning of 16 March. According to the simulation results, the highest radioactive contamination areas around FNPS1 were created from 15 to 16 March by complicated interactions among rainfall, plume movements, and the temporal

  6. Detailed source term estimation of the atmospheric release for the Fukushima Daiichi Nuclear Power Station accident by coupling simulations of atmospheric dispersion model with improved deposition scheme and oceanic dispersion model

    Science.gov (United States)

    Katata, G.; Chino, M.; Kobayashi, T.; Terada, H.; Ota, M.; Nagai, H.; Kajino, M.; Draxler, R.; Hort, M. C.; Malo, A.; Torii, T.; Sanada, Y.

    2014-06-01

    Temporal variations in the amount of radionuclides released into the atmosphere during the Fukushima Dai-ichi Nuclear Power Station (FNPS1) accident and their atmospheric and marine dispersion are essential to evaluate the environmental impacts and resultant radiological doses to the public. In this paper, we estimate a detailed time trend of atmospheric releases during the accident by combining environmental monitoring data with atmospheric model simulations from WSPEEDI-II (Worldwide version of System for Prediction of Environmental Emergency Dose Information), and simulations from the oceanic dispersion model SEA-GEARN-FDM, both developed by the authors. A sophisticated deposition scheme, which deals with dry and fogwater depositions, cloud condensation nuclei (CCN) activation and subsequent wet scavenging due to mixed-phase cloud microphysics (in-cloud scavenging) for radioactive iodine gas (I2 and CH3I) and other particles (CsI, Cs, and Te), was incorporated into WSPEEDI-II to improve the surface deposition calculations. The fallout to the ocean surface calculated by WSPEEDI-II was used as input data for the SEA-GEARN-FDM calculations. Reverse and inverse source-term estimation methods based on coupling the simulations from both models was adopted using air dose rates and concentrations, and sea surface concentrations. The results revealed that the major releases of radionuclides due to FNPS1 accident occurred in the following periods during March 2011: the afternoon of 12 March due to the wet venting and hydrogen explosion at Unit 1, the morning of 13 March after the venting event at Unit 3, midnight of 14 March when the SRV (Safely Relief Valve) at Unit 2 was opened three times, the morning and night of 15 March, and the morning of 16 March. According to the simulation results, the highest radioactive contamination areas around FNPS1 were created from 15 to 16 March by complicated interactions among rainfall, plume movements, and the temporal variation of

  7. Atmospheric Dispersion Modeling of 137Cs generated from Nuclear Spent Fuel under Hypothetic Accidental Condition in the BNPP Area

    Science.gov (United States)

    Lee, Jongkuk; Lee, Kwan-Hee; Yook, Daesik; Kim, Sung Il; Lee, Byung Soo

    2016-04-01

    This study presents the results of atmosphere dispersion modeling using CALPUFF code that are based on computational simulation to evaluate the environmental characteristics of the Barakah nuclear power plant (BNPP) in west area of UAE. According to meteorological data analysis (2012~2013), the winds from the north(7.68%) and west(9.05%) including NNW(41.63%), NW(28.55%), and WNW(6.31%) winds accounted for more than 90% of the wind directions. East(0.2%) and south(0.6%) direction wind, including ESE(0.31%), SE(0.38%), and SSE(0.38%) were rarely distributed during the simulation period. Seasonal effects were not showed. However, a discrepancy in the tendency between daytime and night-time was observed. Approximately 87% of the wind speed was distributed below 5.4m/s (17%, 47% and 23% between the speeds of 0.5-1.8m/s 1.8-3.3m/s and 3.3-5.4m/s, respectively) during the annual period. Seasonal wind speed distribution results presented very similar pattern of annual distribution. Wind speed distribution of day and night, on the other hand, had a discrepancy with annual modeling results than seasonal distribution in some sections. The results for high wind speed (more than 10.8m/s) showed that this wind blew from the west. This high wind speed is known locally as the 'Shamal', which occurs rarely, lasting one or two days with the strongest winds experienced in association with gust fronts and thunderstorms. Six variations of cesium-137 (137Cs) dispersion test were simulated under hypothetic severe accidental condition. The 137Cs dispersion was strongly influenced by the direction and speed of the main wind. From the test cases, east-south area of the BNPP site was mainly influenced by 137Cs dispersion. A virtual receptor was set and calculated for observation of the 137Cs movement and accumulation. Surface roughness tests were performed for the analysis of topographic conditions. According to the surface condition, there are various surface roughness length. Four types

  8. Implementation of a model of atmospheric dispersion and dose calculation in the release of radioactive effluents in the Nuclear Centre

    International Nuclear Information System (INIS)

    In the present thesis, the software DERA (Dispersion of Radioactive Effluents into the Atmosphere) was developed in order to calculate the equivalent dose, external and internal, associated with the release of radioactive effluents into the atmosphere from a nuclear facility. The software describes such emissions in normal operation, and not considering the exceptional situations such as accidents. Several tools were integrated for describing the dispersion of radioactive effluents using site meteorological information (average speed and wind direction and the stability profile). Starting with the calculation of the concentration of the effluent as a function of position, DERA estimates equivalent doses using a set of EPA s and ICRP s coefficients. The software contains a module that integrates a database with these coefficients for a set of 825 different radioisotopes and uses the Gaussian method to calculate the effluents dispersion. This work analyzes how adequate is the Gaussian model to describe emissions type -puff-. Chapter 4 concludes, on the basis of a comparison of the recommended correlations of emissions type -puff-, that under certain conditions (in particular with intermittent emissions) it is possible to perform an adequate description using the Gaussian model. The dispersion coefficients (σy and σz), that using the Gaussian model, were obtained from different correlations given in the literature. Also in Chapter 5 is presented the construction of a particular correlation using Lagrange polynomials, which takes information from the Pasquill-Gifford-Turner curves (PGT). This work also contains a state of the art about the coefficients that relate the concentration with the equivalent dose. This topic is discussed in Chapter 6, including a brief description of the biological-compartmental models developed by the ICRP. The software s development was performed using the programming language Python 2.7, for the Windows operating system (the XP version

  9. Detailed source term estimation of atmospheric release during the Fukushima Dai-ichi nuclear power plant accident by coupling atmospheric and oceanic dispersion models

    Science.gov (United States)

    Katata, Genki; Chino, Masamichi; Terada, Hiroaki; Kobayashi, Takuya; Ota, Masakazu; Nagai, Haruyasu; Kajino, Mizuo

    2014-05-01

    Temporal variations of release amounts of radionuclides during the Fukushima Dai-ichi Nuclear Power Plant (FNPP1) accident and their dispersion process are essential to evaluate the environmental impacts and resultant radiological doses to the public. Here, we estimated a detailed time trend of atmospheric releases during the accident by combining environmental monitoring data and coupling atmospheric and oceanic dispersion simulations by WSPEEDI-II (Worldwide version of System for Prediction of Environmental Emergency Dose Information) and SEA-GEARN developed by the authors. New schemes for wet, dry, and fog depositions of radioactive iodine gas (I2 and CH3I) and other particles (I-131, Te-132, Cs-137, and Cs-134) were incorporated into WSPEEDI-II. The deposition calculated by WSPEEDI-II was used as input data of ocean dispersion calculations by SEA-GEARN. The reverse estimation method based on the simulation by both models assuming unit release rate (1 Bq h-1) was adopted to estimate the source term at the FNPP1 using air dose rate, and air sea surface concentrations. The results suggested that the major release of radionuclides from the FNPP1 occurred in the following periods during March 2011: afternoon on the 12th when the venting and hydrogen explosion occurred at Unit 1, morning on the 13th after the venting event at Unit 3, midnight on the 14th when several openings of SRV (steam relief valve) were conducted at Unit 2, morning and night on the 15th, and morning on the 16th. The modified WSPEEDI-II using the newly estimated source term well reproduced local and regional patterns of air dose rate and surface deposition of I-131 and Cs-137 obtained by airborne observations. Our dispersion simulations also revealed that the highest radioactive contamination areas around FNPP1 were created from 15th to 16th March by complicated interactions among rainfall (wet deposition), plume movements, and phase properties (gas or particle) of I-131 and release rates

  10. Atmospheric dispersion of argon-41 from anuclear research reactor: measurement and modeling of plume geometry and gamma radiation field

    DEFF Research Database (Denmark)

    Lauritzen, Bent; Astrup, Poul; Drews, Martin;

    2003-01-01

    An atmospheric dispersion experiment was conducted using a visible tracer along with the routine release of argon-41 from the BR1 research reactor in Mol, Belgium. Simultaneous measurements of plume geometry and radiation fields for argon-41 decay were performed as well as measurements of the argon...

  11. Nuclear risk from atmospheric dispersion in Northern Europe - Summary Report

    OpenAIRE

    Lauritzen, Bent

    2011-01-01

    The objective of the NordRisk II project has been to derive practical means for assessing the risks from long-range atmospheric dispersion of radioac-tive materials. An atlas over different atmospheric dispersion and deposi-tion scenarios has been developed using historical numerical weather pre-diction (NWP) model data. The NWP model data covers three years span-ning the climate variability associated with the North Atlantic Oscillation, and the atlas considers radioactive releases from 16 r...

  12. A source term estimation method for a nuclear accident using atmospheric dispersion models

    DEFF Research Database (Denmark)

    Kim, Minsik; Ohba, Ryohji; Oura, Masamichi;

    2015-01-01

    models and short-range observational data around the nuclear power plants.The accuracy of this method is validated with data from a wind tunnel study that involved a tracer gas release from a scaled model experiment at Tokai Daini nuclear power station in Japan. We then use the methodology developed...

  13. Modelling the atmospheric dispersion of foot-and-mouth disease virus for emergency preparedness

    DEFF Research Database (Denmark)

    Sørensen, J.H.; Jensen, C.O.; Mikkelsen, T.;

    2001-01-01

    using as input data from the numerical weather prediction model DMI-HIRLAM. The model system is a part of a real-time decision-support system intended for use by veterinary authorities in case of outbreaks of FMD. Results are presented corresponding to historical outbreaks of the disease. (C) 2000...... Elsevier Science Ltd. All rights reserved....

  14. Contaminant dispersion prediction and source estimation with integrated Gaussian-machine learning network model for point source emission in atmosphere.

    Science.gov (United States)

    Ma, Denglong; Zhang, Zaoxiao

    2016-07-01

    Gas dispersion model is important for predicting the gas concentrations when contaminant gas leakage occurs. Intelligent network models such as radial basis function (RBF), back propagation (BP) neural network and support vector machine (SVM) model can be used for gas dispersion prediction. However, the prediction results from these network models with too many inputs based on original monitoring parameters are not in good agreement with the experimental data. Then, a new series of machine learning algorithms (MLA) models combined classic Gaussian model with MLA algorithm has been presented. The prediction results from new models are improved greatly. Among these models, Gaussian-SVM model performs best and its computation time is close to that of classic Gaussian dispersion model. Finally, Gaussian-MLA models were applied to identifying the emission source parameters with the particle swarm optimization (PSO) method. The estimation performance of PSO with Gaussian-MLA is better than that with Gaussian, Lagrangian stochastic (LS) dispersion model and network models based on original monitoring parameters. Hence, the new prediction model based on Gaussian-MLA is potentially a good method to predict contaminant gas dispersion as well as a good forward model in emission source parameters identification problem. PMID:27035273

  15. Data assimilation on atmospheric dispersion of radioactive materials

    DEFF Research Database (Denmark)

    Drews, Martin

    2006-01-01

    During a nuclear accident in which radionuclides are released to the atmosphere, off-site dose assessment using atmospheric dispersion models play an important role in facilitating optimized interventions, i.e. for mitigating the radiological consequences. By using data assimilation methods......, radiological observations, e.g. dose rate measurements, can be used to improve these model predictions and to obtain real-time estimates of the atmospheric dispersion parameters. This thesis examines data assimilation in the context of atmospheric dispersion of radioactive materials. In particular, it presents...... a new method for on-line estimation of the radionuclide source term, i.e. the amount and composition of the released radionuclides, and the main dispersion parameters, based on radiation monitoring data obtained in the vicinity of the release. The method is based on the extended Kalman filter (EKF...

  16. Assessing the Accuracy of the Tracer Dilution Method with Atmospheric Dispersion Modeling

    Science.gov (United States)

    Taylor, D.; Delkash, M.; Chow, F. K.; Imhoff, P. T.

    2015-12-01

    Landfill methane emissions are difficult to estimate due to limited observations and data uncertainty. The mobile tracer dilution method is a widely used and cost-effective approach for predicting landfill methane emissions. The method uses a tracer gas released on the surface of the landfill and measures the concentrations of both methane and the tracer gas downwind. Mobile measurements are conducted with a gas analyzer mounted on a vehicle to capture transects of both gas plumes. The idea behind the method is that if the measurements are performed far enough downwind, the methane plume from the large area source of the landfill and the tracer plume from a small number of point sources will be sufficiently well-mixed to behave similarly, and the ratio between the concentrations will be a good estimate of the ratio between the two emissions rates. The mobile tracer dilution method is sensitive to different factors of the setup such as placement of the tracer release locations and distance from the landfill to the downwind measurements, which have not been thoroughly examined. In this study, numerical modeling is used as an alternative to field measurements to study the sensitivity of the tracer dilution method and provide estimates of measurement accuracy. Using topography and wind conditions for an actual landfill, a landfill emissions rate is prescribed in the model and compared against the emissions rate predicted by application of the tracer dilution method. Two different methane emissions scenarios are simulated: homogeneous emissions over the entire surface of the landfill, and heterogeneous emissions with a hot spot containing 80% of the total emissions where the daily cover area is located. Numerical modeling of the tracer dilution method is a useful tool for evaluating the method without having the expense and labor commitment of multiple field campaigns. Factors tested include number of tracers, distance between tracers, distance from landfill to transect

  17. Dispersion, deposition and resuspension of atmospheric contaminants

    International Nuclear Information System (INIS)

    The following topics are discussed: dry deposition, oil shale fugitive air emissions, particle resuspension and translocation, theoretical studies and applications, and processing of emissions by clouds and precipitation. The concentration of contaminant species in air is governed by the rate of input from sources, the rate of dilution or dispersion as a result of air turbulence, and the rate of removal to the surface by wet and dry deposition processes. Once on the surface, contaminants also may be resuspended, depending on meteorological and surface conditions. An understanding of these processes is necessary for accurate prediction of exposures of hazardous or harmful contaminants to humans, animals, and crops. In the field, plume dispersion and plume depletion by dry deposition were studied by the use of tracers. Dry deposition was investigated for particles of both respiration and inhalation interest. Complementary dry deposition studies of particles to rock canopies were conducted under controlled conditions in a wind tunnel. Because of increasing concern about hazardous, organic gases in the atmosphere some limited investigations of the dry deposition of nitrobenzene to a lichen mat were conducted in a stirred chamber. Resuspension was also studied using tracers and contaminated surfaces and in the wind tunnel. The objective of the resuspension studies was to develop and verify models for predicting the airborne concentrations of contaminants over areas with surface contamination, develop resuspension rate predictors for downwind transport, and develop predictors for resuspension input to the food chain. These models will be of particular relevance to the evaluation of deposition and resuspension of both radionuclides and chemical contaminants

  18. The radiological consequences of notional accidental releases of radioactivity from fast breeder reactors: sensitivity to the choice of atmospheric dispersion model

    International Nuclear Information System (INIS)

    The radiological consequences of a wide range of notional accidental releases from a 1300 MW(e) LMFBR were assessed in a study published in 1977 (NRPB - R53). In that study representative values were in general adopted for each of the important parameters while recognising that in reality they could vary considerably. The present study is concerned with the sensitivity of the predicted consequences to the choice of atmospheric dispersion models. A comparison is made of the air concentrations predicted by a number of atmospheric models (which have found broad application) for releases of activity in selected meteorological conditions. The implications, in terms of the radiological consequences of particular releases, of differences in the air concentrations predicted by the respective models are assessed semi-quantitatively. In general the radiological consequences are shown to be relatively insensitive to the choice of atmospheric dispersion model. This is particularly so for the incidence of late biological effects; for early biological effects the sensitivity is more pronounced although of the models considered, that adopted in the initial study would yield results at the upper end of the predicted range. (author)

  19. Use of MODIS Satellite Images and an Atmospheric Dust Transport Model To Evaluate Juniperus spp. Pollen Phenology and Dispersal

    Science.gov (United States)

    Luvall, J. C.; Sprigg, W. A.; Levetin, Estelle; Huete, Alfredo; Nickovic, S.; Pejanovic, G. A.; Vukovic, A.; VandeWater, P. K.; Myers, O. B.; Budge, A. M.; Zelicoff, A. P.; Bunderson, L.; Crimmins, T. M.

    2011-01-01

    Pollen can be transported great distances. Van de Water et. al., 2003 reported Juniperus spp. pollen was transported 200-600 km. Hence local observations of plant phenology may not be consistent with the timing and source of pollen collected by pollen sampling instruments. The DREAM (Dust REgional Atmospheric Model, Nickovic et al. 2001) is a verified model for atmospheric dust transport modeling using MODIS data products to identify source regions and quantities of dust. We are modifying the DREAM model to incorporate pollen transport. Pollen release will be estimated based on MODIS derived phenology of Juniperus spp. communities. Ground based observational records of pollen release timing and quantities will be used as verification. This information will be used to support the Centers for Disease Control and Prevention's National Environmental Public Health Tracking Program and the State of New Mexico environmental public health decision support for asthma and allergies alerts.

  20. Comparison of RIMPUFF, HYSPLIT, ADMS atmospheric dispersion model outputs, using emergency response procedures, with (85)Kr measurements made in the vicinity of nuclear reprocessing plant.

    Science.gov (United States)

    Connan, Olivier; Smith, Kilian; Organo, Catherine; Solier, Luc; Maro, Denis; Hébert, Didier

    2013-10-01

    The Institut de Radioprotection et de Sureté Nucléaire (IRSN) performed a series of (85)Kr air sampling campaigns at mesoscale distances (18-50 km) from the AREVA NC La Hague nuclear reprocessing plant (North West France) between 2007 and 2009. The samples were collected in order to test and optimise a technique to measure low krypton-85 ((85)Kr) air concentrations and to investigate the performance of three atmospheric dispersion models (RIMPUFF, HYSPLIT, and ADMS), This paper presents the (85)Kr air concentrations measured at three sampling locations which varied from 2 to 8000 Bq m(-3), along with the (85)Kr air concentrations output by the dispersion models. The dispersion models made reasonable estimates of the mean concentrations of (85)Kr field measurements during steady wind conditions. In contrast, the models failed to accurately predict peaks in (85)Kr air concentration during periods of rapid and large changes in wind speed and/or wind direction. At distances where we made the comparisons (18-50 km), in all cases, the models underestimated the air concentration activities.

  1. Some aspects of atmospheric dispersion in the stratified atmospheric boundary layer over homogeneous terrain

    DEFF Research Database (Denmark)

    Gryning, Sven-Erik

    1999-01-01

    the Gaussian plume model concept with the spread parameters described in terms of the Pasquill stability classification or Monin-Obukhov similarity relationships are used. Other model types are Lagrangian particle models which also are parameterized in terms of Monin-Obukhov similarity relationships....... The applied models describe adequately the dispersion process in a weakly stable atmosphere, but fail during very stable atmospheric conditions. This suggests that Monin-Obukhov similarity theory is an adequate tool for the parameterization of the input parameters to atmospheric dispersion models...... during weakly stable conditions, but that more detailed parameterisations including other physical processes than those covered by the Monin-Obukhov theory should be developed for the very stable atmosphere....

  2. Delayed shear enhancement in mesoscale atmospheric dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Moran, M.D. [Atmospheric Environment Service, Ontario (Canada); Pielke, R.A. [Colorado State Univ., Fort Collins, CO (United States)

    1994-12-31

    Mesoscale atmospheric dispersion (MAD) is more complicated than smaller-scale dispersion because the mean wind field can no longer be considered steady or horizontally homogeneous over mesoscale time and space scales. Wind shear also plays a much more important role on the mesoscale: horizontal dispersion can be enhanced and often dominated by vertical wind shear on these scales through the interaction of horizontal differential advection and vertical mixing. Just over 30 years ago, Pasquill suggested that this interaction need not be simultaneous and that the combination of differential horizontal advection with delayed or subsequent vertical mixing could maintain effective horizontal diffusion in spite of temporal or spatial reductions in boundary-layer turbulence intensity. This two-step mechanism has not received much attention since then, but a recent analysis of observations from and numerical simulations of two mesoscale tracer experiments suggests that delayed shear enhancement can play an important role in MAD. This paper presents an overview of this analysis, with particular emphasis on the influence of resolvable vertical shear on MAD in these two case studies and the contributions made by delayed shear enhancement.

  3. Short-range atmospheric dispersion of carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Cortis, A.; Oldenburg, C.M.

    2009-11-01

    We present a numerical study aimed at quantifying the effects of concentration-dependent density on the spread of a seeping plume of CO{sub 2} into the atmosphere such as could arise from a leaking geologic carbon sequestration site. Results of numerical models can be used to supplement field monitoring estimates of CO{sub 2} seepage flux by modelling transport and dispersion between the source emission and concentration-measurement points. We focus on modelling CO{sub 2} seepage dispersion over relatively short distances where density effects are likely to be important. We model dense gas dispersion using the steady-state Reynolds-averaged Navier-Stokes equations with density dependence in the gravity term. Results for a two-dimensional system show that a density dependence emerges at higher fluxes than prior estimates. A universal scaling relation is derived that allows estimation of the flux from concentrations measured downwind and vice versa.

  4. MET-RODOS: A comprehensive atmospheric dispersion module

    DEFF Research Database (Denmark)

    Mikkelsen, T.; Thykier-Nielsen, S.; Astrup, P.;

    1997-01-01

    A comprehensive meteorological dispersion module called MET-RODOS is being developed to serve the real-time RODOS(1-3) decision support system with an integrated prediction capability for airborne radioactive spread, deposition and gamma radiation exposure on all scales. Deposition, ground level...... air concentrations, and ground level gamma dose rates from up to 15 simultaneous released nuclides are calculated using a nested system of local and long range atmospheric dispersion models, driven by real-time available on-line meteorological information. The MET-PODOS module uses concurrently...

  5. Atmospheric Dispersion Analysis using MACCS2

    Energy Technology Data Exchange (ETDEWEB)

    Glaser, R; Yang, J M

    2004-02-02

    The Nuclear Regulatory Commission (NRC) Regulatory Guide 1.145 requires an evaluation of the offsite atmospheric dispersion coefficient, {Chi}/Q, as a part of the acceptance criteria in the accident analysis. In it, it requires in sequence computations of (1) the overall site 95th percentile {Chi}/Q, (2) the maximum of the sixteen sector 99.5th percentile {Chi}/Q, and (3) comparison and selection of the worst of the two values for reporting in the safety analysis report (SAR). In all cases, the site-specific meteorology and sector-specific site boundary distances are employed in the evaluation. There are sixteen 22.5-sectors, the nearest site boundary of which is determined within the 45-arc centered on each of the sixteen compass directions.

  6. A computational model for the rise and dispersion of wind-blown, buoyancy-driven plumes—II. Linearly stratified atmosphere

    Science.gov (United States)

    Zhang, Xiaoming; Ghoniem, Ahmed F.

    A multi-dimensional computational model of wind-blown, buoyancy-driven flows is applied to study the effect of atmospheric stratification on the rise and dispersion of plumes. The model utilizes Lagrangian transport elements, distributed in the plane of the plume cross section normal to the wind direction, to caoture the evolution of the vorticity and density field, and another set of elements to model the dynamics in the atmosphere surrounding the plume. Solutions are obtained for a case in which atmospheric density changes linearly with height. Computational results show that, similar to the case of a neutrally stratified atmosphere, the plume acquires a kidney-shaped cross section which persists for a long distance downstream the source and may bifurcate into separate and distinct lumps. Baroclinic vortivity generated both along the plume boundary and in the surroundings is used to explain the origin of the distortion experienced by the plume and the inhibiting effect of a stratified atmosphere, respectively. The vorticity within the plume cross section forms two large-scale coherent eddies which are responsible for the plume motion and the entrainment. Prior to reaching the equilibrium height, the computed plume trajectory is found to follow the two-thirds law, when extended to include the initial plume size, reasonably well. Entrainment and added mass coefficients equal to 0.49 and 0.7 respectively, are obtained from the numerical results over a wide range of the buoyancy ratio, defined as the ratio between the plume buoyancy and the degree of background stratification. In the case of strong stratification, the plume trajectory shows weak, fast decaying oscillations around the equilibrium height.

  7. Estimation of NH3 emissions from a naturally ventilated livestock farm using local-scale atmospheric dispersion modelling

    Directory of Open Access Journals (Sweden)

    P. Cellier

    2009-01-01

    Full Text Available Agricultural livestock represents the main source of ammonia (NH3 in Europe. In recent years, reduction policies have been applied to reduce NH3 emissions. In order to estimate the impacts of these policies, robust estimates of the emissions from the main sources, i.e. livestock farms are needed. In this paper, the NH3 emissions were estimated from a naturally ventilated livestock farm in Braunschweig, Germany during a joint field experiment of the GRAMINAE European project. An inference method was used with a Gaussian-3-D plume model and a local-scale dispersion and deposition model (FIDES-2-D. NH3 concentrations downwind of the source were used together with micrometeorological data to estimate the source strength over time. Mobile NH3 concentration measurements provided information on the spatial distribution of source strength. The estimated emission strength ranged between 6.0±0.17 kg NH3 d−1 (FIDES-2-D model and 9.2±0.7 kg NH3 d−1 (Gaussian model. These estimates were 94% and 63% of what was obtained using emission factors from the German national inventory (9.6 kg d−1 NH3. However, the FIDES-2-D approach was shown to be very sensitive to the source size, the roughness height and to whether deposition was taken into account downwind of the source. Accounting for deposition in FIDES-2-D gives a potential emission estimate of 11.7 kg NH3 d−1, showing that deposition can explain the observed difference. The daily pattern of the source was correlated with net radiation and with the temperature inside the animal houses. The daily pattern resulted from a combination of a temperature effect on the source concentration together with an effect of variations in free and forced convection of the building ventilation rate. Further development of the plume technique is especially relevant for naturally ventilated farms, since the variable ventilation rate makes other emission measurements difficult.

  8. Investigation of the interaction between sources and sinks of atmospheric ammonia in an upland landscape using a simplified dispersion-exchange model

    Science.gov (United States)

    Loubet, Benjamin; Milford, Celia; Sutton, Mark A.; Cellier, Pierre

    2001-10-01

    Exchange of atmospheric ammonia (NH3) with vegetation is characterized by the juxtaposition of sources and sinks at a landscape level. Such situations lead to a large fraction of the landscape being exposed to local advection effects that if not accounted for, introduce errors in standard micrometeorological measurements of NH3 exchange with the surface. In this study, a simplified dispersion - exchange model for NH3 (Flux Interpretation by Dispersion and Exchange over Short Range, FIDES) is evaluated and used to assess the advection fluxes at 260 m downwind of an isolated pasture, grazed with sheep, using the measurements of a classical three-point NH3 gradient system located on adjacent moorland. The method consists of fitting the measured and modeled concentration profile by adjusting at the same time the emission strength of the local source and the exchange rate of NH3 to the moorland area downwind. A local dispersion and surface exchange model such as FIDES has proved to be a valuable tool to estimate advection corrections, given sound estimates of background NH3 concentrations, source location, and standard meteorological parameters. According to the model results the advection fluxes at the moorland measurement site, at 1.0 m height and 260 m downwind of the grazed pasture, were positive. For 80% of the situations they ranged between 30% and 60% of the vertical flaxes. In stable conditions the advection fluxes were large and more sensitive to the surface exchange parameters. These results demonstrate that if not accounted for, advection fluxes may lead to a severe underestimate of the NH3 deposition to seminatural ecosystems, such as moorland, in the vicinity of ground level agricultural sources.

  9. Atmospheric dispersion modeling of hazardous air pollutant emissions from USDOE Oak Ridge Reservation Facilities. Volume 1, Independent Assessment conducted from April 1994 to December 1994

    International Nuclear Information System (INIS)

    Title 3 of the 1990 Clean Air Act (CAA) Amendments addresses the emissions of 189 hazardous air pollutants (HAPs) and mandates that EPA develop technology-based [Maximum Achievable Control Technology (MACT)] standards for the control of these pollutants from approximately 174 source categories. After implementation of technology-based standards, EPA is required to further evaluate ''residual risk'' from HAP emissions, and, if required, develop more stringent standards to protect human health and the environment with an ''adequate margin of safety''. Recognizing that EPA will be issuing risk-based regulations after MACT standards have been implemented, the US Department of Energy (DOE), Oak Ridge Operations Office (ORO) has conducted an evaluation of ambient air impacts of HAP emissions from its installations located on the Oak Ridge Reservation (ORR) near Oak Ridge, Tennessee. This report provides results of atmospheric dispersion modeling conducted to determine ambient air impacts of HAP emissions from facilities located on the ORR

  10. Dense gas dispersion in the atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, Morten

    1998-09-01

    Dense gas dispersion is characterized by buoyancy induced gravity currents and reduction of the vertical mixing. Liquefied gas releases from industrial accidents are cold because of the heat of evaporation which determines the density for a given concentration and physical properties. The temperature deficit is moderated by the heat flux from the ground, and this convection is an additional source of turbulence which affects the mixing. A simple model as the soil heat flux is used to estimate the ability of the ground to sustain the heat flux during release. The initial enthalpy, release rate, initial entrainment and momentum are discussed for generic source types and the interaction with obstacles is considered. In the MTH project BA experiments source with and without momentum were applied. The continuously released propane gas passed a two-dimensional removable obstacle perpendicular to the wind direction. Ground-level gas concentrations and vertical profiles of concentration, temperature, wind speed and turbulence were measured in front of and behind the obstacle. Ultrasonic anemometers providing fast velocity and concentration signals were mounted at three levels on the masts. The observed turbulence was influenced by the stability and the initial momentum of the jet releases. Additional information were taken from the `Dessert tortoise` ammonia jet releases, from the `Fladis` experiment with transition from dense to passive dispersion, and from the `Thorney Island` continuous releases of isothermal freon mixtures. The heat flux was found to moderate the negative buoyancy in both the propane and ammonia experiments. The heat flux measurements are compared to an estimate by analogy with surface layer theory. (au) 41 tabs., 146 ills., 189 refs.

  11. Simulation of atmospheric dispersion of radioactivity from the Chernobyl accident

    International Nuclear Information System (INIS)

    Measurements of airborne radioactivity over Europe, Japan, and the United States indicated that the release from the Chernobyl reactor accident in the Soviet Union on April 26, 1986 contained a wide spectrum of fission up to heights of 7 km or more within a few days after the initial explosion. This high-altitude presence of radioactivity would in part be attributable to atmospheric dynamics factors other than the thermal energy released in the initial explosion. Indications were that two types of releases had taken place -- an initial powerful explosion followed by days of a less energetic reactor fire. The Atmospheric Release Advisory Capability (ARAC) at the Lawrence Livermore National Laboratory (LLNL) utilized three-dimensional atmospheric dispersion models to determine the characteristics of the source term (release) and the evolution of the spatial distributions of the airborne radioactivity as it was transported over Europe and subsequently over the northern hemisphere. This paper describes the ARAC involvement and the results of the hemispheric model calculations which graphically depict the extensive dispersal of radioactivity. 1 fig

  12. Atmospheric dispersion of pollutants in an industrial area of Cuba

    International Nuclear Information System (INIS)

    Air pollution by different chemicals; take a great connotation in the world, given the adverse effects on ecosystems and particularly human health. The urban development, the modification of the land surface and the climate change, phenomena derived from a world population explosion, are altering the composition of the air. The atmosphere deposits pollutants in the water courses and in land, which harms not only the persons, but also to the animals and the plants of the ecosystem. To know as these pollutants are dispersed in the atmosphere it is very important in the establishment of better urban, regional and world predictions of the air quality. The present study aims to assess the local spread of sulphur dioxide, nitrogen oxides and particulate matter from an industrial zone. The study was done using the pollutant Gaussian Dispersion Models AERMOD. For the evaluation of contaminants were considered two modeling scenarios: urban and rural. The SO2 concentrations (μg/m3) were obtained for 1 h, 24 h and all period (1 year), exceeding the permissible limits (500, 50 y 20 μg/m3). It was also recorded for each period the number of times SO2 concentrations exceeded the reference values in each of the scenarios discussed (urban: 39, 61 y 39; rural: 99, 75 y 25). At the end of modeling in the urban setting, 39 recipients exceeded the reference value, occupying an area of 9.75 km2 and 25 receivers in the case of the rural setting, for an area of 6.25 km2. For NOx and particulate matter concentrations estimated values were always below the reference values. The obtained results in this case show the potentiality of AERMOD system for the evaluation of atmospheric dispersion of pollutants

  13. Atmospheric dispersion calculations in a low mountain area

    International Nuclear Information System (INIS)

    The applicability of the Gaussian model for assessing the short-range environmental exposure from an emission source in a topographically inhomogeneous terrain is tested. An atmospheric dispersion model of general applicability is used, which is based on results of hydrodynamic flow models. Approaches for turbulence and radiation parameterization are tested by means of a vertically one-dimensional flow model. In order to introduce the effects of the topography in the boundary-layer simulations, the three-dimensional mesoscale model (Ulrich) is applied. The two models are verified by way of episode simulation using wind profile measurements. The differences in the models' results are to show the topographic influence. The calculated flow fields serve as input to a randomwalk model applied for calculating ground-level concentration fields in the vicinity of an emission source. The Gaussian model underestimates the pollution under stable conditions. Convectivity conditions may change the effective source hight through vertical effects caused by orography which, depending on the direction of free flow, leads to an increase or decrease of pollutant concentration at ground level. Applying the more complex dispersion model, the concentration maxima under stable conditions are closer to the source by a factor five, and under unstable conditions about one and a half times more remote. (orig./HP)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  15. Evaluation of ensemble atmospheric simulations in oil dispersion models at Itaguai Port region; Avaliacao do uso de resultados numericos de previsao atmosferica por conjunto na modelagem da dispersao de oleo na regiao do Porto de Itaguai

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Renato Goncalves dos; Silva, Mariana P.R.; Silva, Ricardo Marcelo da; Torres Junior, Audalio R. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Lab. de Modelagem de Processos Marinhos e Atmosfericos (LAMMA); Landau, Luiz [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Lab. de Metodos Computacinais em Engenharia (LAMCE); Sa, Reginaldo Ventura de; Hochleitner, Fabio; Correa, Eduardo Barbosa [AQUAMET Meteorologia e Projeto de Sistemas, Rio de Janeiro, RJ (Brazil)

    2008-07-01

    This work discusses the use of numerical prediction using ensemble as boundary condition in pollutants dispersion models, applied in a hypothetical case of an oil spill occurrence in Itaguai Port. The Princeton Ocean Model (POM) has been used to simulate hydrodynamics and NICOIL Eulerian model to forecast oil spill dispersion, and ensemble wind forecast from Global Forecast System (GFS), aiming to assess the importance of this parameter variability in oil dispersion at sea. The wind scenarios using ensemble members has showed significant dispersion when compared to control simulation, demonstrating that the uncertainty in the atmospheric modeling can generate considerable variations in the placement of the final spot of oil. The region of interest was the Sepetiba Bay, located on the southern coast of the Rio de Janeiro state; because of port operations carried out around the Port of Itaguai where they can, eventually, oil leaks occur. (author)

  16. Operational mesoscale atmospheric dispersion prediction using a parallel computing cluster

    Indian Academy of Sciences (India)

    C V Srinivas; R Venkatesan; N V Muralidharan; Someshwar Das; Hari Dass; P Eswara Kumar

    2006-06-01

    An operational atmospheric dispersion prediction system is implemented on a cluster supercomputer for Online Emergency Response at the Kalpakkam nuclear site.This numerical system constitutes a parallel version of a nested grid meso-scale meteorological model MM5 coupled to a random walk particle dispersion model FLEXPART.The system provides 48-hour forecast of the local weather and radioactive plume dispersion due to hypothetical airborne releases in a range of 100 km around the site.The parallel code was implemented on different cluster con figurations like distributed and shared memory systems.A 16-node dual Xeon distributed memory gigabit ethernet cluster has been found sufficient for operational applications.The runtime of a triple nested domain MM5 is about 4 h for a 24 h forecast.The system had been operated continuously for a few months and results were ported on the IMSc home page. Initial and periodic boundary condition data for MM5 are provided by NCMRWF,New Delhi. An alternative source is found to be NCEP,USA.These two sources provide the input data to the operational models at different spatial and temporal resolutions using different assimilation methods.A comparative study on the results of forecast is presented using these two data sources for present operational use.Improvement is noticed in rainfall forecasts that used NCEP data, probably because of its high spatial and temporal resolution.

  17. Atmospheric dispersion in complex terrain: Angra-1 nuclear power plant

    International Nuclear Information System (INIS)

    The Angra 1 plant is located in a very complex terrain, what makes the environmental impact assessment very difficult, regarding to the atmospheric transport problem as well as to the diffusion problem. Three main characteristics are responsible for that situation: the location at the shoreline, the complex topography and the high roughness of the terrain. Those characteristics generate specific phenomena and utilization of parameters from other sites are not convenient. Considering financial and technical viabilities, we must look for the local parameters, disregarding the easy, although risky, attitude of applying parameters and models incovenient to the Angra site. Some of those aspects are more important, and among them we will discuss the Plume Rise, the Critical Height, the Drainage Flow and the Atmospheric Dispersion Coefficients. (Author)

  18. Estimation of NH3 emissions from a naturally ventilated livestock farm using local-scale atmospheric dispersion modelling

    Science.gov (United States)

    Hensen, A.; Loubet, B.; Mosquera, J.; van den Bulk, W. C. M.; Erisman, J. W.; Dämmgen, U.; Milford, C.; Löpmeier, F. J.; Cellier, P.; Mikuška, P.; Sutton, M. A.

    2009-12-01

    Agricultural livestock represents the main source of ammonia (NH3) in Europe. In recent years, reduction policies have been applied to reduce NH3 emissions. In order to estimate the impacts of these policies, robust estimates of the emissions from the main sources, i.e. livestock farms are needed. In this paper, the NH3 emissions were estimated from a naturally ventilated livestock farm in Braunschweig, Germany during a joint field experiment of the GRAMINAE European project. An inference method was used with a Gaussian-3D plume model and with the Huang 3-D model. NH3 concentrations downwind of the source were used together with micrometeorological data to estimate the source strength over time. Mobile NH3 concentration measurements provided information on the spatial distribution of source strength. The estimated emission strength ranged between 6.4±0.18 kg NH3 d-1 (Huang 3-D model) and 9.2±0.7 kg NH3 d-1 (Gaussian-3D model). These estimates were 94% and 63% of what was obtained using emission factors from the German national inventory (9.6 kg d-1 NH3). The effect of deposition was evaluated with the FIDES-2D model. This increased the emission estimate to 11.7 kg NH3 d-1, showing that deposition can explain the observed difference. The daily pattern of the source was correlated with net radiation and with the temperature inside the animal houses. The daily pattern resulted from a combination of a temperature effect on the source concentration together with an effect of variations in free and forced convection of the building ventilation rate. Further development of the plume technique is especially relevant for naturally ventilated farms, since the variable ventilation rate makes other emission measurements difficult.

  19. Estimation of NH3 emissions from a naturally ventilated livestock farm using local-scale atmospheric dispersion modelling

    Directory of Open Access Journals (Sweden)

    P. Cellier

    2009-12-01

    Full Text Available Agricultural livestock represents the main source of ammonia (NH3 in Europe. In recent years, reduction policies have been applied to reduce NH3 emissions. In order to estimate the impacts of these policies, robust estimates of the emissions from the main sources, i.e. livestock farms are needed. In this paper, the NH3 emissions were estimated from a naturally ventilated livestock farm in Braunschweig, Germany during a joint field experiment of the GRAMINAE European project. An inference method was used with a Gaussian-3D plume model and with the Huang 3-D model. NH3 concentrations downwind of the source were used together with micrometeorological data to estimate the source strength over time. Mobile NH3 concentration measurements provided information on the spatial distribution of source strength. The estimated emission strength ranged between 6.4±0.18 kg NH3 d−1 (Huang 3-D model and 9.2±0.7 kg NH3 d−1 (Gaussian-3D model. These estimates were 94% and 63% of what was obtained using emission factors from the German national inventory (9.6 kg d−1 NH3. The effect of deposition was evaluated with the FIDES-2D model. This increased the emission estimate to 11.7 kg NH3 d−1, showing that deposition can explain the observed difference. The daily pattern of the source was correlated with net radiation and with the temperature inside the animal houses. The daily pattern resulted from a combination of a temperature effect on the source concentration together with an effect of variations in free and forced convection of the building ventilation rate. Further development of the plume technique is especially relevant for naturally ventilated farms, since the variable ventilation rate makes other emission measurements difficult.

  20. CFD Simulations of Joint Urban Atmospheric Dispersion Field Study

    Energy Technology Data Exchange (ETDEWEB)

    Lee, R; Humphreys III, T; Chan, S

    2004-06-17

    The application of Computational Fluid Dynamics (CFD) to the understanding of urban wind flow and dispersion processes has gained increasing attention over recent years. While many of the simpler dispersion models are based on a set of prescribed meteorology to calculate dispersion, the CFD approach has the ability of coupling the wind field to dispersion processes. This has distinct advantages when very detailed results are required, such as for the case where the releases occur around buildings and within urban areas. CFD also has great flexibility as a testbed for turbulence models, which has important implications for atmospheric dispersion problems. In the spring of 2003, a series of dispersion field experiments (Joint Urban 2003) were conducted at Oklahoma City (Allwine, et. al, 2004). These experiments were complimentary to the URBAN 2000 field studies at Salt Lake City (Shinn, et. al, 2000) in that they will provide a second set of comprehensive field data for evaluation of CFD as well as for other dispersion models. In contrast to the URBAN 2000 experiments that were conducted entirely at night, these new field studies took place during both daytime and nighttime thus including the possibility of convective as well as stable atmospheric conditions. Initially several CFD modeling studies were performed to provide guidance for the experimental team in the selection of release sites and in the deployment of wind and concentration sensors. Also, while meteorological and concentration measurements were taken over the greater Oklahoma City urban area, our CFD calculations were focused on the near field of the release point. The proximity of the source to a large commercial building and to the neighboring buildings several of which have multistories, present a significant challenge even for CFD calculations involving grid resolutions as fine as 1 meter. A total of 10 Intensive Observations Periods (IOP's) were conducted within the 2003 field experiments. SF6

  1. Numerical modeling of atmospheric flow and dispersion around a mountain%大气绕山体的运动及其输移特性的研究

    Institute of Scientific and Technical Information of China (English)

    李玲; 木村繁男

    2007-01-01

    对分层大气山体绕流的流动模式及扩散输移特性进行了数值模拟.采用隐式时间离散方法在贴体网格系统下求解雷诺平均的N-S方程,计算结果描述出大气流动的特征,证实了分层(以Froude数为特征参数,定义为F=U/NH,U为来流风速,N为Brunt-Vaisala频率,H为山体高度)变化对山体绕流流态的影响.数值结果表明:当Froude数大于4.0时,山体绕流的流动不再依赖于大气分层的变化.当Froude数介于4.0和1.0之间时,流场中出现了Lee波,并随着Froude数的进一步减小,流动分离发生及Lee波破碎现象.同时模型也预测了在各种流动模式下大气中夹杂着的污染物绕山体的传输特性,表明大气的分层现象对污染物的分布有着非常重要的影响.%A series of numerical experiments had been conducted to investigate the flow patterns and dispersion characteristics around a mountain under stably stratified flow. The two-dimensional model equations, based on the time-dependent Reynolds averaged Navier-Stokes equations, were solved numerically using an implicit time integration in body-fitted grid arrangement. The behavior of the flow is clarified to ascertain the effects of changes in the stratification, which is characterized by the Froude number F = U/NH (Where U is speed of the approaching wind, N is the Brunt-Vaisala frequency, and H is the mountain height). The numerical results suggest that the flow structure is independent of stratification when F>4.0. The model predicts lee wave generation as the Froude number is decreased from 4 to 1, then flow splitting, wave breaking phenomena happen as F is further decreased to less than 1.0. Further, the model-predicted concentration fields when the contaminant is coming with the approaching wind show that the stratification of atmospheric flow has significant effects on the dispersion pattern.

  2. High performance dispersion model PHYSIC

    Energy Technology Data Exchange (ETDEWEB)

    Yamazawa, Hiromi (Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment)

    1992-07-01

    The description and usage of the dispersion calculation model PHYSIC were summarized. The model was developed in the study of developing high performance SPEEDI with the purpose of introducing meteorological forecast function into the environmental emergency response system. PHYSIC consists of two parts, the three-dimensional meteorological model and the dispersion model. The former comprises primitive equations with Boussinesq approximation, which are solved by a finite difference method. The latter employs a particle dispersion method. PHYSIC can be used to evaluate the meteorological condition as well as the dispersion from a point source located in a complex terrain. The spatial and temporal scales of the model are 10 to 1000 km horizontally, 1 to 10 km vertically and 1 hour to 1 day, respectively. (author).

  3. Large-eddy simulation and Lagrangian stochastic modelling of solid particle and droplet dispersion and mixing. Application to atmospheric pollution; Dispersion et melange turbulents de particules solides et de gouttelettes par une simulation des grandes echelles et une modelisation stochastique lagrangienne. Application a la pollution de l'atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Vinkovic, I.

    2005-07-15

    In order to study atmospheric pollution and the dispersion of industrial stack emissions, a large eddy simulation with the dynamic Smagorinsky-Germano sub-grid-scale model is coupled with Lagrangian tracking of fluid particles containing scalar, solid particles and droplets. The movement of fluid particles at a sub-grid level is given by a three-dimensional Langevin model. The stochastic model is written in terms of sub-grid-scale statistics at a mesh level. By introducing a diffusion model, the coupling between the large-eddy simulation and the modified three-dimensional Langevin model is applied to passive scalar dispersion. The results are validated by comparison with the wind-tunnel experiments of Fackrell and Robins (1982). The equation of motion of a small rigid sphere in a turbulent flow is introduced. Solid particles and droplets are tracked in a Lagrangian way. The velocity of solid particles and droplets is considered to have a large scale component (directly computed by the large-eddy simulation) and a sub-grid scale part. Because of inertia and gravity effects, solid particles and droplets, deviate from the trajectories of the surrounding fluid particles. Therefore, a modified Lagrangian correlation timescale is introduced into the Langevin model previously developed for the sub-grid velocity of fluid particles. Two-way coupling and collisions are taken into account. The results of the large-eddy simulation with solid particles are compared with the wind-tunnel experiments of Nalpanis et al. (1993) and of Taniere et al. (1997) on sand particles in saltation and in modified saltation, respectively. A model for droplet coalescence and breakup is implemented which allows to predict droplet interactions under turbulent flow conditions in the frame of the Euler/Lagrange approach. Coalescence and breakup are considered as a stochastic process with simple scaling symmetry assumption for the droplet radius, initially proposed by Kolmogorov (1941). At high

  4. Method for the instant approximation of atmospheric dispersion

    International Nuclear Information System (INIS)

    Mathematical evaluations of the radiologic impact of the transfer to man of radionuclides liberated into the environment are made with complex chains of models in which an early and essential link is always that of dispersion in air or water where the basic evaluations involve concentrations. In practice it often happens that the link of the concentration in the physical environment is overdeveloped in comparison to the other links and that the corresponding models are unnecessarily complicated. It appeared useful to develop a very simple basic primary model with few disagreements compatible with all of the existing models that it does not presume to replace. Naturally this model implies a certain number of stringent simplifying hypotheses, but at each point of space or time it only has a single parameter, the mixture thickness, real or equivalent, to characterize turbulent diffusion. A basic formula covering the short- and long-term situations, as well as transfers both within the atmosphere and to the ground (deposits) is supplied in the form of a single summary table. 4 references, 1 figure, 1 table

  5. Modeling volcanic ash dispersal

    CERN Document Server

    CERN. Geneva

    2010-01-01

    The assessment of volcanic fallout hazard is an important scientific, economic, and political issue, especially in densely populated areas. From a scientific point of view, considerable progress has been made during the last two decades through the use of increasingly powerful computational models and capabilities. Nowadays, models are used to quantify hazard...

  6. Nonisothermal Pluto atmosphere models

    International Nuclear Information System (INIS)

    The present thermal profile calculation for a Pluto atmosphere model characterized by a high number fraction of CH4 molecules encompasses atmospheric heating by solar UV flux absorption and conductive transport cooling to the surface of Pluto. The stellar occultation curve predicted for an atmosphere of several-microbar surface pressures (which entail the existence of a substantial temperature gradient close to the surface) agrees with observations and implies that the normal and tangential optical depth of the atmosphere is almost negligible. The minimum period for atmospheric methane depletion is calculated to be 30 years. 29 refs

  7. Atmospheric dispersion and the implications for phase calibration

    CERN Document Server

    Curtis, Emily I; Richer, John S; Pardo, Juan R

    2009-01-01

    The success of any ALMA phase-calibration strategy, which incorporates phase transfer, depends on a good understanding of how the atmospheric path delay changes with frequency (e.g. Holdaway & Pardo 2001). We explore how the wet dispersive path delay varies for realistic atmospheric conditions at the ALMA site using the ATM transmission code. We find the wet dispersive path delay becomes a significant fraction (>5 per cent) of the non-dispersive delay for the high-frequency ALMA bands (>160 GHz, Bands 5 to 10). Additionally, the variation in dispersive path delay across ALMA's 4-GHz contiguous bandwidth is not significant except in Bands 9 and 10. The ratio of dispersive path delay to total column of water vapour does not vary significantly for typical amounts of water vapour, water vapour scale heights and ground pressures above Chajnantor. However, the temperature profile and particularly the ground-level temperature are more important. Given the likely constraints from ALMA's ancillary calibration devi...

  8. Footprints and footprint analysis for atmospheric dispersion problems

    CERN Document Server

    Brännström, Niklas

    2014-01-01

    Footprint analysis, also known as the study of Influence areas, is a first order method for solving inverse atmospheric dispersion problems. We revisit the concept of footprints giving a rigorous definition of the concept (denoted posterior footprints and posterior zero footprints) in terms of spatio-temporal domains. The notion of footprints is then augmented the to the forward dispersion problem by defining prior footprints and prior zero footprints. We then study how posterior footprints and posterior zero footprints can be combined to reveal more information about the source, and how prior footprints and prior footprints can be combined to yield more information about the measurements.

  9. Numerical modelling and parametric study of the atmospheric dispersion after radionuclide releases: the Chernobyl accident and the Algeciras incident. Comparison with observation data

    International Nuclear Information System (INIS)

    Full text: The attempts of modelling the release following upon the Chernobyl accident and the Algeciras incident are reported. Computing power and observation database are used for sensitivity and parametric studies. The meteorological mesoscale model MM5 is nudged with the ERA-40 reanalysis to simulate the meteorological conditions used by the dispersion model, POLAIR3D. In case of the Chernobyl accident the points of interest are many: the representativity of the meteorological simulations is evaluated using observations with a special focus on precipitation events. The radionuclide dispersion, the dry deposition and scavenging simulated by POLAIR3D are compared with European measurements of activities and depositions. Results of the sensitivity studies are done to evaluate the impact of the deposition parameterizations and source-term characteristics (height of release, quantities). The time dynamic of the contaminated cloud is also investigated with regard to the arrival time on different countries. Similarly, for the Algeciras release, sensitivity to the meteorological fields, source term and depletion processes are analyzed. For the available activity concentrations in the air, data-model comparisons are performed. (author)

  10. An atmospheric dispersion model for linear sources in calm wind, stable conditions; Un modello di dispersione atmosferica per sorgenti lineari in condizioni di vento debole

    Energy Technology Data Exchange (ETDEWEB)

    Cirillo, M. C. [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dipt. Ambiente; Buratti, D. [Rome Univ. La Sapienza, Rome (Italy). Facolta' di Scienze Statistiche; Metallo, M. C.; Poli, A.A. [ESA s.a.s., Bracciano, RM (Italy)

    1999-07-01

    In this report a dispersion model is proposed that provides an estimate of concentration of gaseous pollutants emitted by an highway, or in general by a line source, in presence of low wind speed. This aim was pursued because available models have not a satisfactory behaviour in such conditions, which is critical for dispersion of gaseous pollutants. This lack is due to difficulty of simulating dispersion turbulent component which is determined by fluctuation of wind speed and wind direction, and in presence of calm conditions it assumes values comparable with transport component. The proposed model overcomes this difficulty, as it is shown by sensitivity analysis and comparison with experimental data. The capability of simulating dispersion eve in critical conditions, like the presence of low level inversion, and the absence of source geometrical approximations make the model a tool that, properly used, may contribute to the efficient planning and management of environmental resources. [Italian] In questo rapporto viene proposto un modello per la stima delle concentrazioni di inquinanti aeriformi emessi da un'arteria stradale, o in generale da una sorgente lineare, in presenza di vento debole. Questo scopo e' stato perseguito in quanto in questa condizione, nonostante la dispersione degli inquinanti risulti fortemente problematica, i modelli disponibili in letteratura non hanno un comportamento soddisfacente. Questa mancanca e' attribuibile alla difficolta' di simulare la componente turbolenta della dispersione, dovuta alla fluttuazione della direzione e della velocita' del vento che, in presenza di vento debole, assume valori confrontabili alla componente di trasporto. Il modello qui di seguito proposto supera questa difficolta', come dimostrano l'analisi di sensibilita' e il confronto con un caso reale; la capacita' di simulare la dispersione anche in condizioni fisicamente critiche quali la presenza di inversione a

  11. Coupling constant in dispersive model

    Indian Academy of Sciences (India)

    R Saleh-Moghaddam; M E Zomorrodian

    2013-11-01

    The average of the moments for event shapes in + - → hadrons within the context of next-to-leading order (NLO) perturbative QCD prediction in dispersive model is studied. Moments used in this article are $\\langle 1 - T \\rangle, \\langle ρ \\rangle, \\langle B_{T} \\rangle$ and $\\langle B_{W} \\rangle$. We extract , the coupling constant in perturbative theory and α0 in the non-perturbative theory using the dispersive model. By fitting the experimental data, the values of $(M_{Z^{°}})$ = 0.1171 ± 0.00229 and 0 ($_{I} = 2{\\text{GeV}}$) = 0.5068 ± 0.0440 are found. Our results are consistent with the above model. Our results are also consistent with those obtained from other experiments at different energies. All these features are explained in this paper.

  12. The brasimone study (brastud) an investigation of atmospheric dispersion over complex terrain

    International Nuclear Information System (INIS)

    An investigation of atmospheric dispersion over complex terrain was carried out in September 1984 and in June 1985 at the Brasimone Energy Research Centre (B.E.R.C.). This place, where an experimental nuclear reactor is under construction, is located in the Tuscan-Emilian Appennine range approximately 50 km south of Bologna. The measuring campaigns, based on survey of wind and temperature parameters, tracer (SF6) experiments and tracking of tetroons by radar, were performed with the purpose of assessing the atmospheric dispersion of pollutants under nocturnal drainage flow conditions. The three-dimensional MATHEW/ADPIC model was evaluated with the Brasimone data set and the results obtained are satisfactory

  13. Solar Atmosphere Models

    Science.gov (United States)

    Rutten, R. J.

    2002-12-01

    This contribution honoring Kees de Jager's 80th birthday is a review of "one-dimensional" solar atmosphere modeling that followed on the initial "Utrecht Reference Photosphere" of Heintze, Hubenet & de Jager (1964). My starting point is the Bilderberg conference, convened by de Jager in 1967 at the time when NLTE radiative transfer theory became mature. The resulting Bilderberg model was quickly superseded by the HSRA and later by the VAL-FAL sequence of increasingly sophisticated NLTE continuum-fitting models from Harvard. They became the "standard models" of solar atmosphere physics, but Holweger's relatively simple LTE line-fitting model still persists as a favorite of solar abundance determiners. After a brief model inventory I discuss subsequent work on the major modeling issues (coherency, NLTE, dynamics) listed as to-do items by de Jager in 1968. The present conclusion is that one-dimensional modeling recovers Schwarzschild's (1906) finding that the lower solar atmosphere is grosso modo in radiative equilibrium. This is a boon for applications regarding the solar atmosphere as one-dimensional stellar example - but the real sun, including all the intricate phenomena that now constitute the mainstay of solar physics, is vastly more interesting.

  14. Lagrangian modeling of atmospheric dispersion of radionuclides and geographical information systems as tools to support emergency planning in area of influence of nuclear complex of Angra dos Reis, RJ, Brazil

    International Nuclear Information System (INIS)

    Industrial accidents generally endanger structures and the set of environmental influence area where the enterprises are located, especially when affected by atmospheric dispersion of their pollutants, whose concern with the evacuation of the population is the main goal in emergency situations. Considering the nuclear complex Angra dos Reis - RJ, based on computer modeling analysis of the mechanisms of pollutant dispersion in conjunction with geographic information systems were developed. Thus, information about the dispersion of radionuclides - from simulations performed on the HYSPLIT; meteorological data (direction, intensity and calm on the wind regime and analysis of the wind field in the region using WRF), occurrence of landslides and data on the environmental study area were integrated into a GIS database using ArcGIS platform. Aiming at the identification and definition of escape routes in case of evacuation from accidental events in CNAAA, the results point solutions for long-term planning, based on weather and landslides, and short-term, supported by simulations of the dispersion radionuclides, in order to support actions that assist local emergency planning. (author)

  15. Review of specific effects in atmospheric dispersion calculations

    International Nuclear Information System (INIS)

    This report consists of a series of 7 individual review chapters -written between 1980 and 1983- together with a summary document linking and overviewing the work. The topics covered are as follows: ''atmospheric dispersion in urban environments''; ''topographical effects in nuclear safety studies''; coastal effects and transport over water''; ''time-varying meteorology in consequence assessment''; ''building effects in nuclear safety studies''; effect of variations in mixing height on atmospheric dispersion''; ''the effect of turning of the wind with height on lateral dispersion''. Although the reviews are, on the whole, general in approach, emphasis has been given where appropriate to the impact of various phenomena on the assessment of reactor accident consequences. In general the work focuses on the 0-100 km range of distance downwind of the source. The reviews fulfil several functions: they serve as introductions to the subject areas; they outline theoretical and experimental developments; they act as reference documents providing a copious source of references for more detailed investigation of particular points; they raise unresolved technical issues and attempt to indicate principal uncertainties; they point to areas requiring further development

  16. CFD SIMULATIONS OF JOINT URBAN ATMOSPHERE DISPERSION FIELD STUDY 2003

    Energy Technology Data Exchange (ETDEWEB)

    Lee, R L; Humphreys, T D; Chan, S T

    2004-03-31

    In the Spring of 2003, a series of dispersion field experiments (Joint Urban 2003) were conducted at Oklahoma City. These experiments were complimentary to the URBAN 2000 field studies at Salt Lake City (Allwine, et. al, 2002) in that they will provide a second set of comprehensive field data for evaluation of CFD as well as for other dispersion models. In contrast to the URBAN 2000 experiments that were conducted entirely at night, these new field studies took place during both daytime and nighttime thus including the possibility of convective as well as stable atmospheric conditions. Initially several CFD modeling studies were performed to provide guidance for the experimental team in the selection of release sites and in the deployment of wind and concentration sensors. Also, while meteorological and concentration measurements were taken over the greater Oklahoma City urban area, our CFD calculations were focused on the near field of the release point. The proximity of the source to a large commercial building and to the neighboring buildings several of which have multi-stories, present a significant challenge even for CFD calculations involving grid resolutions as fine as 1 meter. A total of 10 Intensive Observations Periods (IOP's) were conducted within the 2003 field experiments. SF{sub 6} releases in the form of puffs or continuous sources were disseminated over 6 daytime and 4 nighttime episodes. Many wind and concentration sensors were used to provide wind and SF{sub 6} data over both long and short time-averaging periods. In addition to the usual near surface measurements, data depicting vertical profiles of wind and concentrations adjacent to the outside walls several building were also taken. Also of interest were observations of the trajectory of balloons that were released closed to the tracer release area. Many of the balloons released exhibit extremely quick ascents up from ground level to the top of buildings, thus implying highly convective

  17. Lateral Dispersion of Pollutants in a Very Stable Atmosphere - The Effect of Meandering

    DEFF Research Database (Denmark)

    Kristensen, Leif; Jensen, Niels Otto; Lundtang Petersen, Erik

    1981-01-01

    A model based on single particle diffusion is introduced to account for the effect of “meandering” on lateral plume dispersion in a very stable atmosphere. It is assumed that small scale atmospheric turbulence is absent, so that only large horizontal eddies are effective. A formula for the lateral....... Meteorological data from Risø and the small island Sprogø have been analysed in order to identify all situations in which the atmosphere is so stable that small scale turbulence cannot exist. The purpose is to see in how many of these situations meandering is also absent. The results show that, as a rule...

  18. Modified ensemble Kalman filter for nuclear accident atmospheric dispersion: prediction improved and source estimated.

    Science.gov (United States)

    Zhang, X L; Su, G F; Yuan, H Y; Chen, J G; Huang, Q Y

    2014-09-15

    Atmospheric dispersion models play an important role in nuclear power plant accident management. A reliable estimation of radioactive material distribution in short range (about 50 km) is in urgent need for population sheltering and evacuation planning. However, the meteorological data and the source term which greatly influence the accuracy of the atmospheric dispersion models are usually poorly known at the early phase of the emergency. In this study, a modified ensemble Kalman filter data assimilation method in conjunction with a Lagrangian puff-model is proposed to simultaneously improve the model prediction and reconstruct the source terms for short range atmospheric dispersion using the off-site environmental monitoring data. Four main uncertainty parameters are considered: source release rate, plume rise height, wind speed and wind direction. Twin experiments show that the method effectively improves the predicted concentration distribution, and the temporal profiles of source release rate and plume rise height are also successfully reconstructed. Moreover, the time lag in the response of ensemble Kalman filter is shortened. The method proposed here can be a useful tool not only in the nuclear power plant accident emergency management but also in other similar situation where hazardous material is released into the atmosphere.

  19. Modified ensemble Kalman filter for nuclear accident atmospheric dispersion: Prediction improved and source estimated

    International Nuclear Information System (INIS)

    Highlights: • A modified ensemble Kalmen filter data assimilation method is proposed. • The method can consider four main uncertain parameters in the puff model. • The prediction of radioactive material atmospheric dispersion is improved. • The source release rate and plume rise height are successfully reconstructed. • It can shorten the time lag in the response of ensemble Kalmen filter. - Abstract: Atmospheric dispersion models play an important role in nuclear power plant accident management. A reliable estimation of radioactive material distribution in short range (about 50 km) is in urgent need for population sheltering and evacuation planning. However, the meteorological data and the source term which greatly influence the accuracy of the atmospheric dispersion models are usually poorly known at the early phase of the emergency. In this study, a modified ensemble Kalman filter data assimilation method in conjunction with a Lagrangian puff-model is proposed to simultaneously improve the model prediction and reconstruct the source terms for short range atmospheric dispersion using the off-site environmental monitoring data. Four main uncertainty parameters are considered: source release rate, plume rise height, wind speed and wind direction. Twin experiments show that the method effectively improves the predicted concentration distribution, and the temporal profiles of source release rate and plume rise height are also successfully reconstructed. Moreover, the time lag in the response of ensemble Kalman filter is shortened. The method proposed here can be a useful tool not only in the nuclear power plant accident emergency management but also in other similar situation where hazardous material is released into the atmosphere

  20. A user's guide to the atmospheric dispersion module NECTAR-ATMOS

    International Nuclear Information System (INIS)

    The NECTAR environmental computer code has been developed to meet the increasing demand for comprehensive calculations of the radiological consequences due to atmospheric releases of radioactivity. The code contains five calculational modules and this report presents a user's guide to the atmospheric dispersion and individual dose evaluation module NECTAR-ATMOS. The mathematical models employed in NECTAR-ATMOS are briefly described and a complete specification of the input data required for the module is given. The program includes facilities for reading in the source terms, for specifying the atmospheric dispersion parameters, for identifying the dose calculations required and for controlling output from the program to lineprinters and to output utility files. Three sample cases are included in an appendix to demonstrate some of the different ways in which the program may be used and also to provide examples for the prospective user. (author)

  1. Global risk from the atmospheric dispersion of radionuclides by nuclear power plant accidents in the coming decades

    OpenAIRE

    Christoudias, T.; Proestos, Y.; Lelieveld, J.

    2014-01-01

    We estimate the global risk from the release and atmospheric dispersion of radionuclides from nuclear power plant accidents using the EMAC atmospheric chemistry–general circulation model. We included all nuclear reactors that are currently operational, under construction and planned or proposed. We implemented constant continuous emissions from each location in the model and simulated atmospheric transport and removal via dry and wet deposition processes over 20 years (2010–...

  2. Modeling electrical dispersion phenomena in Earth materials

    OpenAIRE

    D. Patella

    2008-01-01

    It is illustrated that IP phenomena in rocks can be described using conductivity dispersion models deduced as solutions to a 2nd-order linear differential equation describing the motion of a charged particle immersed in an external electrical field. Five dispersion laws are discussed, namely: the non-resonant positive IP model, which leads to the classical Debye-type dispersion law and by extension to the Cole-Cole model, largely used in current practice; the non-resonant negative...

  3. A hybrid plume model for local-scale dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Nikmo, J.; Tuovinen, J.P.; Kukkonen, J.; Valkama, I.

    1997-12-31

    The report describes the contribution of the Finnish Meteorological Institute to the project `Dispersion from Strongly Buoyant Sources`, under the `Environment` programme of the European Union. The project addresses the atmospheric dispersion of gases and particles emitted from typical fires in warehouses and chemical stores. In the study only the `passive plume` regime, in which the influence of plume buoyancy is no longer important, is addressed. The mathematical model developed and its numerical testing is discussed. The model is based on atmospheric boundary-layer scaling theory. In the vicinity of the source, Gaussian equations are used in both the horizontal and vertical directions. After a specified transition distance, gradient transfer theory is applied in the vertical direction, while the horizontal dispersion is still assumed to be Gaussian. The dispersion parameters and eddy diffusivity are modelled in a form which facilitates the use of a meteorological pre-processor. Also a new model for the vertical eddy diffusivity (K{sub z}), which is a continuous function of height in the various atmospheric scaling regions is presented. The model includes a treatment of the dry deposition of gases and particulate matter, but wet deposition has been neglected. A numerical solver for the atmospheric diffusion equation (ADE) has been developed. The accuracy of the numerical model was analysed by comparing the model predictions with two analytical solutions of ADE. The numerical deviations of the model predictions from these analytic solutions were less than two per cent for the computational regime. The report gives numerical results for the vertical profiles of the eddy diffusivity and the dispersion parameters, and shows spatial concentration distributions in various atmospheric conditions 39 refs.

  4. Nuclear risk from atmospheric dispersion in Northern Europe - Summary Report

    DEFF Research Database (Denmark)

    Lauritzen, Bent

    -diction (NWP) model data. The NWP model data covers three years span-ning the climate variability associated with the North Atlantic Oscillation, and the atlas considers radioactive releases from 16 release sites in and near the Nordic countries. A statistical analysis of the long-range disper...... parameterization of the global dispersion and deposition patterns. The atlas and the underlying data are made available in a format compati-ble with the ARGOS decision support system, and have been imple-mented in ARGOS....

  5. A high precision technique to correct for residual atmospheric dispersion in high-contrast imaging systems

    CERN Document Server

    Pathak, P; Jovanovic, N; Lozi, J; Martinache, F; Minowa, Y; Kudo, T; Takami, H; Hayano, Y; Narita, N

    2016-01-01

    Direct detection and spectroscopy of exoplanets requires high contrast imaging. For habitable exoplanets in particular, located at small angular separation from the host star, it is crucial to employ small inner working angle (IWA) coronagraphs that efficiently suppress starlight. These coronagraphs, in turn, require careful control of the wavefront which directly impacts their performance. For ground-based telescopes, atmospheric refraction is also an important factor, since it results in a smearing of the PSF, that can no longer be efficiently suppressed by the coronagraph. Traditionally, atmospheric refraction is compensated for by an atmospheric dispersion compensator (ADC). ADC control relies on an a priori model of the atmosphere whose parameters are solely based on the pointing of the telescope, which can result in imperfect compensation. For a high contrast instrument like the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) system, which employs very small IWA coronagraphs, refraction-induced sm...

  6. Discrete dispersion models and their Tweedie asymptotics

    DEFF Research Database (Denmark)

    Jørgensen, Bent; Kokonendji, Célestin C.

    2016-01-01

    approach, whereas several overdispersed discrete distributions, such as the Neyman Type A, Pólya-Aeppli, negative binomial and Poisson-inverse Gaussian, turn out to be Poisson-Tweedie factorial dispersion models with power dispersion functions, analogous to ordinary Tweedie exponential dispersion models...... with power variance functions. Using the factorial cumulant generating function as tool, we introduce a dilation operation as a discrete analogue of scaling, generalizing binomial thinning. The Poisson-Tweedie factorial dispersion models are closed under dilation, which in turn leads to a Poisson...

  7. Modeling the atmospheric chemistry of TICs

    Science.gov (United States)

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

    2009-05-01

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

  8. Modelling airborne dispersion of coarse particulate material

    International Nuclear Information System (INIS)

    Methods of modelling the airborne dispersion and deposition of coarse particulates are presented, with the emphasis on the heavy particles identified as possible constituents of releases from damaged AGR fuel. The first part of this report establishes the physical characteristics of the irradiated particulate in airborne emissions from AGR stations. The second part is less specific and describes procedures for extending current dispersion/deposition models to incorporate a coarse particulate component: the adjustment to plume spread parameters, dispersion from elevated sources and dispersion in conjunction with building effects and plume rise. (author)

  9. Inverse problems using ANN in long range atmospheric dispersion with signature analysis picked scattered numerical sensors from CFD

    International Nuclear Information System (INIS)

    Scalar dispersion in the atmosphere is an important area wherein different approaches are followed in development of good analytical model. The analyses based on Computational Fluid Dynamics (CFD) codes offer an opportunity of model development based on first principles of physics and hence such models have an edge over the existing models. Both forward and backward calculation methods are being developed for atmospheric dispersion around NPPs at BARC Forward modeling methods, which describe the atmospheric transport from sources to receptors, use forward-running transport and dispersion models or computational fluid dynamics models which are run many times, and the resulting dispersion field is compared to observations from multiple sensors. Backward or inverse modeling methods use only one model run in the reverse direction from the receptors to estimate the upwind sources. Inverse modeling methods include adjoint and tangent linear models, Kalman filters, and variational data assimilation, and neural network. The present paper is aimed at developing a new approach where the identified specific signatures at receptor points form the basis for source estimation or inversions. This approach is expected to reduce the large transient data sets to reduced and meaningful data sets. In fact this reduces the inherently transient data set into a time independent mean data set. Forward computation were carried out with CFD code for various case to generate a large set of data to train the ANN. Specific signature analysis was carried out to find the parameters of interest for ANN training like peak concentration, time to reach peak concentration and time to fall, the ANN was trained with data and source strength and location were predicted from ANN. Inverse problem was performed using ANN approach in long range atmospheric dispersion. An illustration of application of CFD code for atmospheric dispersion studies for a hypothetical case is also included in the paper. (author)

  10. Real time analysis for atmospheric dispersions for Fukushima nuclear accident: Mobile phone based cloud computing assessment

    International Nuclear Information System (INIS)

    Highlights: • Possible nuclear accident is simulated for the atmospheric contaminations. • The simulations results give the relative importance of the fallouts. • The cloud computing of IT is performed successfully. • One can prepare for the possible damages of such a NPP accident. • Some other variables can be considered in the modeling. - Abstract: The radioactive material dispersion is investigated by the system dynamics (SD) method. The non-linear complex algorithm could give the information about the hazardous material behavior in the case of nuclear accident. The prevailing westerlies region is modeled for the dynamical consequences of the Fukushima nuclear accident. The event sequence shows the scenario from earthquake to dispersion of the radionuclides. Then, the dispersion reaches two cities in Korea. The importance of the radioactive dispersion is related to the fast and reliable data processing, which could be accomplished by cloud computing concept. The values of multiplications for the wind, plume concentrations, and cloud computing factor are obtained. The highest value is 94.13 in the 206th day for Seoul. In Pusan, the highest value is 15.48 in the 219th day. The source is obtained as dispersion of radionuclide multiplied by 100. The real time safety assessment is accomplished by mobile phone

  11. Case study of the atmospheric dispersion of emissions from UPPR/CDTN, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Barreto, Alberto A.; Cesar, Raisa H.S.; Maleta, Paulo G.M.; Grossi, Pablo A., E-mail: aab@cdtn.br, E-mail: raisa.hsc@gmail.com, E-mail: pgmm@cdtn.br, E-mail: pablo@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2015-07-01

    This work presents a study of the atmospheric dispersion of emissions released during activities of production and research of radiopharmaceuticals in the Center of Nuclear Technology Development (CDTN), localized in Belo Horizonte, Minas Gerais - Brazil. The installation, 'Unidade de Producao e Pesquisa de Radiofarmacos' (UPPR), was considered operating full time during a year. The general goal was to evaluate the radiological environmental impact due to these atmospheric emissions. The pollutants studied were the radionuclides F-18, C-11 and N-13. The meteorological view evaluated was a period of 365 days, simulated from the dates of a typical meteorological year. It was applied the dispersion model ARTM (Atmospheric Radionuclide Transport Model). The atmospheric emissions from UPPR were estimated for the simulation based in an extremely conservative operation condition. Others important data raised and analyzed were: topography, obstacles (buildings) and the land occupation around the CDTN. Among the main results, it is important to emphasize the estimate of the radionuclide concentration and the dose value calculated from these concentration. These results were compared with the dose restriction limit set by the standard CNEN 3.01. Areas of higher concentration were identified and are being used as reference for the positioning of the concentration's monitor of the pollutant by the Radiological Environmental Monitoring Program (PMA). (author)

  12. MARCS model atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Plez, B [GRAAL, CNRS, UMR5024, Universite Montpellier 2, F-34095 Montpellier, Cedex 5 (France) and Department of Physics and Astronomy, Uppsala University, SE-75120 Uppsala (Sweden)], E-mail: bertrand.plez@graal.univ-montp2.fr

    2008-12-15

    In this review presented at the Symposium A Stellar Journey in Uppsala, June 2008, I give an account of the historical development of the MARCS code, and its premises from the first version published in 1975 to the 2008 grid. The primary driver for the development team who constantly strive to include the best possible physical data, is the science that can be done with the models. A few preliminary comparisons of M star model spectra to spectrophotometric observations are presented. Particular results related to opacity effects are discussed. The size of errors in spectral energy distribution (SED) and model thermal stratification is estimated for different densities of wavelength sampling. The number of points used in the MARCS 2008 grid (108 000) is large enough to ensure errors of only a few K in all models of the grid, except the optically very thin layers of metal-poor stars. Errors in SEDs may reach about 10% locally in the UV. The published sampled SEDs are thus adequate to compute synthetic broadband photometry, but higher resolution spectra will be computed in the near future and published as well on the MARCS site (marcs.astro.uu.se). Test model calculations with TiO line opacity accounted for in scattering show significant cooling of the upper atmospheric layers of red giants. Rough estimates of radiative and collisional time scales for electronic transitions of TiO indicate that scattering may well be the dominant mechanism in these lines. However, models constructed with this hypothesis are incompatible with optical observations of TiO (Arcturus) or IR observations of OH (Betelgeuse), although they may succeed in explaining H{sub 2}O line observations. More work is needed in that direction.

  13. MARCS model atmospheres

    Science.gov (United States)

    Plez, B.

    2008-12-01

    In this review presented at the Symposium A Stellar Journey in Uppsala, June 2008, I give an account of the historical development of the MARCS code, and its premises from the first version published in 1975 to the 2008 grid. The primary driver for the development team who constantly strive to include the best possible physical data, is the science that can be done with the models. A few preliminary comparisons of M star model spectra to spectrophotometric observations are presented. Particular results related to opacity effects are discussed. The size of errors in spectral energy distribution (SED) and model thermal stratification is estimated for different densities of wavelength sampling. The number of points used in the MARCS 2008 grid (108 000) is large enough to ensure errors of only a few K in all models of the grid, except the optically very thin layers of metal-poor stars. Errors in SEDs may reach about 10% locally in the UV. The published sampled SEDs are thus adequate to compute synthetic broadband photometry, but higher resolution spectra will be computed in the near future and published as well on the MARCS site (marcs.astro.uu.se). Test model calculations with TiO line opacity accounted for in scattering show significant cooling of the upper atmospheric layers of red giants. Rough estimates of radiative and collisional time scales for electronic transitions of TiO indicate that scattering may well be the dominant mechanism in these lines. However, models constructed with this hypothesis are incompatible with optical observations of TiO (Arcturus) or IR observations of OH (Betelgeuse), although they may succeed in explaining H2O line observations. More work is needed in that direction.

  14. Study of LPG Release & Dispersion Model

    Institute of Scientific and Technical Information of China (English)

    Mu Shanjun; Peng Xiangwei

    2003-01-01

    The current applicable release & dispersion models are reviewed. A typical model is developed on the basis of LPG storage conditions in China and the authors' research. The study is focused on the relationship between LPG composition and release rate, and on the influence of buildings or structures located in the surrounding area on the dispersion of gas plume. The established model is compared with existing models by the use of published field test data.

  15. A CFD approach to the atmospheric dispersion of radionuclides in the vicinity of NPPs

    Energy Technology Data Exchange (ETDEWEB)

    Sampaio, Paulo A.B. de; Goncalves Junior, Milton A.; Lapa, Celso M.F. [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)]. E-mails: sampaio@ien.gov.br; miago@ien.gov.br; lapa@ien.gov.br

    2007-07-01

    Most studies of atmospheric dispersion of radionuclides released from Nuclear Power Plants (NPPs) are based on Gaussian plume models or on the use of a convection-diffusion equation. Such methods, which do not involve solving the flow problem, are useful in the atmospheric mesoscale, of the order of 2-2000 km from the NPP. However, they do not account for the turbulence generated by the interaction of the wind with obstacles and with the released material stream, which are the dominant factors in the local scale, of the order of 0-2 km from the source of emission. In order to study the dispersion of radionuclides in the vicinity of NPPs, the authors advocate the use of Computational Fluid Dynamics (CFD). The physical model is based on the Navier- Stokes equations, a convection-diffusion energy equation, and transport equations for the radionuclides. The stabilized finite element formulation employed results in a Large Eddy Simulation procedure, where no explicit subgrid modeling is required. The code uses adaptive techniques combining error estimation and remeshing. It has been implemented in a Beowulf parallel computing system using domain decomposition and the Message Passing Interface (MPI) for communication among processors. Both controlled emissions from a chimney and severe accidents have been simulated, showing the importance of the local phenomena on the dispersion of radionuclides. (author)

  16. Atmospheric Dispersal and Dispostion of Tephra From a Potential Volcanic Eruption at Yucca Mountain, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    G. Keating; W.Statham

    2004-02-12

    The purpose of this model report is to provide documentation of the conceptual and mathematical model (ASHPLUME) for atmospheric dispersal and subsequent deposition of ash on the land surface from a potential volcanic eruption at Yucca Mountain, Nevada. This report also documents the ash (tephra) redistribution conceptual model. The ASHPLUME conceptual model accounts for incorporation and entrainment of waste fuel particles associated with a hypothetical volcanic eruption through the Yucca Mountain repository and downwind transport of contaminated tephra. The ASHPLUME mathematical model describes the conceptual model in mathematical terms to allow for prediction of radioactive waste/ash deposition on the ground surface given that the hypothetical eruptive event occurs. This model report also describes the conceptual model for tephra redistribution from a basaltic cinder cone. Sensitivity analyses and model validation activities for the ash dispersal and redistribution models are also presented. Analyses documented in this model report will improve and clarify the previous documentation of the ASHPLUME mathematical model and its application to the Total System Performance Assessment (TSPA) for the License Application (TSPA-LA) igneous scenarios. This model report also documents the redistribution model product outputs based on analyses to support the conceptual model.

  17. Predictability of the dispersion of Fukushima-derived radionuclides and their homogenization in the atmosphere

    Science.gov (United States)

    Mészáros, Róbert; Leelőssy, Ádám; Kovács, Tibor; Lagzi, István

    2016-01-01

    Long-range simulation of the dispersion of air pollutants in the atmosphere is one of the most challenging tasks in geosciences. Application of precise and fast numerical models in risk management and decision support can save human lives and can diminish consequences of an accidental release. Disaster at Fukushima Daiichi nuclear power plant has been the most serious event in the nuclear technology and industry in the recent years. We present and discuss the results of the numerical simulations on dispersion of Fukushima-derived particulate 131I and 137Cs using a global scale Lagrangian particle model. We compare concentrations and arrival times, using two emission scenarios, with the measured data obtained from 182 monitoring stations located all over the Northern Hemisphere. We also investigate the homogenization of isotopes in the atmosphere. Peak concentrations were predicted with typical accuracy of one order of magnitude showing a general underestimation in the case of 131I but not for 137Cs. Tropical and Arctic plumes, as well as the early detections in American and European midlatitudes were generally well predicted, however, the later regional-scale mixing could not be captured by the model. Our investigation highlights the importance of the parameterization of free atmospheric turbulence.

  18. Modeling electrical dispersion phenomena in Earth materials

    Directory of Open Access Journals (Sweden)

    D. Patella

    2008-06-01

    Full Text Available It is illustrated that IP phenomena in rocks can be described using conductivity dispersion models deduced as solutions to a 2nd-order linear differential equation describing the motion of a charged particle immersed in an external electrical field. Five dispersion laws are discussed, namely: the non-resonant positive IP model, which leads to the classical Debye-type dispersion law and by extension to the Cole-Cole model, largely used in current practice; the non-resonant negative IP model, which allows negative chargeability values, known in metals at high frequencies, to be explained as an intrinsic physical property of earth materials in specific field cases; the resonant flat, positive or negative IP models, which can explain the presence of peak effects at specific frequencies superimposed on flat, positive or negative dispersion spectra.

  19. A CFD approach to the atmospheric dispersion of radionuclides in the vicinity of NPPs

    Energy Technology Data Exchange (ETDEWEB)

    Sampaio, Paulo A.B. [Programa de Pos-Graduacao em Ciencia e Tecnologia Nucleares, Instituto de Engenharia Nuclear/CNEN, CP 68550, CEP 21945-970, Rio de Janeiro, RJ (Brazil)], E-mail: sampaio@ien.gov.br; Junior, Milton A.G.; Lapa, Celso M.F. [Programa de Pos-Graduacao em Ciencia e Tecnologia Nucleares, Instituto de Engenharia Nuclear/CNEN, CP 68550, CEP 21945-970, Rio de Janeiro, RJ (Brazil)

    2008-01-15

    Most studies of atmospheric dispersion of radionuclides released from Nuclear Power Plants (NPPs) are based on Gaussian plume models or on the use of a convection-diffusion equation. Such methods, which do not involve solving the flow problem, are useful in the atmospheric mesoscale, of the order of 2-2000 km from the NPP. However, they do not account for the turbulence generated by the interaction of the wind with obstacles and with the released material stream, which are the dominant factors in the local scale, of the order of 0-2 km from the source of emission. Here, the authors advocate the use of computational fluid dynamics (CFD) to study the dispersion problem. The physical model comprises the Navier-Stokes equations, a convection-diffusion energy equation, and transport equations for the radionuclides. The paper details the stabilized finite element formulation used, stressing its connection with the variational multiscale/large eddy simulation approach. Adaptive techniques combining error estimation and remeshing are also employed. The method is implemented on a Beowulf parallel computing system using domain decomposition and the message passing interface (MPI). Controlled emissions from a chimney and release from severe accidents have been simulated, showing the importance of the local phenomena on the dispersion problem.

  20. ATMOSPHERIC DISPERSAL AND DEPOSITION OF TEPHRA FROM A POTENTIAL VOLCANIC ERUPTION AT YUCCA MOUNTAIN, NEVADA

    Energy Technology Data Exchange (ETDEWEB)

    C. Harrington

    2004-10-25

    The purpose of this model report is to provide documentation of the conceptual and mathematical model (Ashplume) for atmospheric dispersal and subsequent deposition of ash on the land surface from a potential volcanic eruption at Yucca Mountain, Nevada. This report also documents the ash (tephra) redistribution conceptual model. These aspects of volcanism-related dose calculation are described in the context of the entire igneous disruptive events conceptual model in ''Characterize Framework for Igneous Activity'' (BSC 2004 [DIRS 169989], Section 6.1.1). The Ashplume conceptual model accounts for incorporation and entrainment of waste fuel particles associated with a hypothetical volcanic eruption through the Yucca Mountain repository and downwind transport of contaminated tephra. The Ashplume mathematical model describes the conceptual model in mathematical terms to allow for prediction of radioactive waste/ash deposition on the ground surface given that the hypothetical eruptive event occurs. This model report also describes the conceptual model for tephra redistribution from a basaltic cinder cone. Sensitivity analyses and model validation activities for the ash dispersal and redistribution models are also presented. Analyses documented in this model report update the previous documentation of the Ashplume mathematical model and its application to the Total System Performance Assessment (TSPA) for the License Application (TSPA-LA) igneous scenarios. This model report also documents the redistribution model product outputs based on analyses to support the conceptual model. In this report, ''Ashplume'' is used when referring to the atmospheric dispersal model and ''ASHPLUME'' is used when referencing the code of that model. Two analysis and model reports provide direct inputs to this model report, namely ''Characterize Eruptive Processes at Yucca Mountain, Nevada and Number of Waste Packages Hit

  1. A dispersion modelling system for urban air pollution

    Energy Technology Data Exchange (ETDEWEB)

    Karppinen, A.; Kukkonen, J.; Nordlund, G.; Rantakrans, E.; Valkama, I.

    1998-10-01

    An Urban Dispersion Modelling system UDM-FMI, developed at the Finnish Meteorological Institute is described in the report. The modelling system includes a multiple source Gaussian plume model and a meteorological pre-processing model. The dispersion model is an integrated urban scale model, taking into account of all source categories (point, line, area and volume sources). It includes a treatment of chemical transformation (for NO{sub 2}) wet and dry deposition (for SO{sub 2}) plume rise, downwash phenomena and dispersion of inert particles. The model allows also for the influence of a finite mixing height. The model structure is mainly based on the state-of-the-art methodology. The system also computes statistical parameters from the time series, which can be compared to air quality guidelines. The relevant meteorological parameters for the dispersion model are evaluated using data produced by a meteorological pre-processor. The model is based mainly on the energy budget method. Results of national investigations have been used for evaluating climate-dependent parameters. The model utilises the synoptic meteorological observations, radiation records and aerological sounding observations. The model results include the hourly time series of the relevant atmospheric turbulence 51 refs.

  2. Physical models of polarization mode dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Menyuk, C.R.; Wai, P.K.A. [Univ. of Maryland, Baltimore, MD (United States)

    1995-12-31

    The effect of randomly varying birefringence on light propagation in optical fibers is studied theoretically in the parameter regime that will be used for long-distance communications. In this regime, the birefringence is large and varies very rapidly in comparison to the nonlinear and dispersive scale lengths. We determine the polarization mode dispersion, and we show that physically realistic models yield the same result for polarization mode dispersion as earlier heuristic models that were introduced by Poole. We also prove an ergodic theorem.

  3. Modeling 137CS dispersion from a radiological dispersion device

    International Nuclear Information System (INIS)

    This analysis reveals that, if terrorists detonate a RDD containing a relatively small amount of 137Cs (approximately 12-35g), the resulting dispersion can contaminate a relatively large area. The actual magnitude of a terrorist incident involving the release of radioactive material by a dirty bomb depends on the dimensions of the contaminated area and the accompanying contamination density (i.e., radioactivity) distributed within that area. Applying a semiempirical model indicates that the spatial extent of the contaminated area and the level of activity within that area are dependent primarily on local scale meteorological conditions, especially whether rainfall occurs, as well particle size and effective release height. As a result, the magnitude of the consequences of terrorists acquiring non-weapons grade nuclear materials and releasing those materials with a dirty bomb is contingent on a number of factors beyond the scope of active countermeasures, especially the RDD's design elements and local-scale meteorological conditions. Modeling the dispersion of radioactive aerosols throughout an urban landscape, especially with accurate 3-D representation of its complex geometry and meteorology, is indispensable for assessing the potential consequences of a terrorist incident and implementing effective emergency response, health services, and decontamination decisions. (orig.)

  4. Kalman filtration of radiation monitoring data from atmospheric dispersion of radioactive materials

    DEFF Research Database (Denmark)

    Drews, M.; Lauritzen, B.; Madsen, H.;

    2004-01-01

    A Kalman filter method using off-site radiation monitoring data is proposed as a tool for on-line estimation of the source term for short-range atmospheric dispersion of radioactive materials. The method is based on the Gaussian plume model, in which the plume parameters including the source term...... exhibit a ‘random walk’ process. The embedded parameters of the Kalman filter are determined through maximum-likelihood estimation making the filter essentially free of external parameters. The method is tested using both real and simulated radiation monitoring data. For simulated data, the method...

  5. NKS-B NordRisk II: Nuclear risk from atmospheric dispersion in Northern Europe - Summary report

    International Nuclear Information System (INIS)

    The objective of the NordRisk II project has been to derive practical means for assessing the risks from long-range atmospheric dispersion of radioactive materials. An atlas over different atmospheric dispersion and deposition scenarios has been developed using historical numerical weather prediction (NWP) model data. The NWP model data covers three years spanning the climate variability associated with the North Atlantic Oscillation, and the atlas considers radioactive releases from 16 release sites in and near the Nordic countries. A statistical analysis of the long-range dispersion and deposition patterns is undertaken to quantify the mean dispersion and deposition as well as the variability. Preliminary analyses show that the large-scale atmospheric dispersion and deposition is near-isotropic, irrespective of the release site and detailed climatology, and allows for a simple parameterization of the global dispersion and deposition patterns. The atlas and the underlying data are made available in a format compatible with the ARGOS decision support system, and have been implemented in ARGOS. (Author)

  6. Regional scale atmospheric dispersion simulation of accidental releases of radionuclides from Fukushima Dai-ichi reactor

    Science.gov (United States)

    Srinivas, C. V.; Venkatesan, R.; Baskaran, R.; Rajagopal, V.; Venkatraman, B.

    2012-12-01

    This paper presents the results of regional scale atmospheric dispersion simulation of accidental emission of radionuclides from the Fukushima Daiichi Reactor, Japan following the Tohoku earthquake and tsunami event on 11 March 2011. The objective was to study the temporal behaviour of plume trajectory, concentration, deposition and radiation dose pattern over an 80 km range around the reactor. The time-varying meteorological parameters during the release period were simulated with a multi-scale nested atmospheric model WRF ARW and the trajectory, plume dispersion were computed with Lagrangian Particle Dispersion models HYSPLIT, FLEXPART using the available information on accidental source term. The simulations indicated that the wind flow over Japan during the release period was driven by the large scale extra-tropical westerly waves and associated low pressure systems. In the lower levels, the flow was influenced by the local topography/sea breeze causing occasional landward wind shift on the east coast of Japan. Simulated airflow trajectories revealed that the plume stayed over the ocean by westerly winds on most days and the radioactivity dispersed over sea surface. Landward trajectories were found on a few days due to southeasterly, easterly and northeasterly flow (15-17, 19-21 March 2011) during which much of the radionuclides deposited over the land region. The hotspot of depositions occurred over east Pacific Ocean near to Japan. Over the land relatively high depositions were simulated in a narrow zone of 20 km width and 80 km length in the northwest sector in agreement with monitor data. Simulations showed wet depositions over the land to be higher than the dry depositions during 12-30 March due to occurrence of rainfall on some days. Comparison of activity deposition and air dose values with available observations confirmed that the plume pattern in a finer length scale around the site could be simulated realistically and agree with the measurements

  7. Implementation of a model of atmospheric dispersion and dose calculation in the release of radioactive effluents in the Nuclear Centre; Implementacion de un modelo de dispersion atmosferica y calculo de dosis en la liberacion de efluentes radiactivos en el Centro Nuclear

    Energy Technology Data Exchange (ETDEWEB)

    Cruz L, C. A.

    2015-07-01

    In the present thesis, the software DERA (Dispersion of Radioactive Effluents into the Atmosphere) was developed in order to calculate the equivalent dose, external and internal, associated with the release of radioactive effluents into the atmosphere from a nuclear facility. The software describes such emissions in normal operation, and not considering the exceptional situations such as accidents. Several tools were integrated for describing the dispersion of radioactive effluents using site meteorological information (average speed and wind direction and the stability profile). Starting with the calculation of the concentration of the effluent as a function of position, DERA estimates equivalent doses using a set of EPA s and ICRP s coefficients. The software contains a module that integrates a database with these coefficients for a set of 825 different radioisotopes and uses the Gaussian method to calculate the effluents dispersion. This work analyzes how adequate is the Gaussian model to describe emissions type -puff-. Chapter 4 concludes, on the basis of a comparison of the recommended correlations of emissions type -puff-, that under certain conditions (in particular with intermittent emissions) it is possible to perform an adequate description using the Gaussian model. The dispersion coefficients (σ{sub y} and σ{sub z}), that using the Gaussian model, were obtained from different correlations given in the literature. Also in Chapter 5 is presented the construction of a particular correlation using Lagrange polynomials, which takes information from the Pasquill-Gifford-Turner curves (PGT). This work also contains a state of the art about the coefficients that relate the concentration with the equivalent dose. This topic is discussed in Chapter 6, including a brief description of the biological-compartmental models developed by the ICRP. The software s development was performed using the programming language Python 2.7, for the Windows operating system (the

  8. Modeling pollutants dispersion in surrounding places to thermoelectric power plants

    International Nuclear Information System (INIS)

    In the Electrical Research Institute (IIE) have been carried out some studies on determination of concentration levels of atmospheric pollutants in areas where is located some thermoelectric central of the Electricity Federal Commission (CFE). These studies have as main objective to collect judgement elements that allow to take measurements for avoiding the environmental damage. At the present time it has been performed modelations of dispersion of atmospheric pollutants on surroundings of thermoelectric centrals, such as Lerdo, Manzanillo, Mazatlan, Monterrey, Rio Escondido, Salamanca, Mexico and Tula's Valley. Therefore in the present work has been included some generalities about the experiences gained in those studies. (Author)

  9. Analysis and demonstration of atmospheric methane monitoring by mid-infrared open-path chirped laser dispersion spectroscopy.

    Science.gov (United States)

    Daghestani, Nart S; Brownsword, Richard; Weidmann, Damien

    2014-12-15

    Atmospheric methane concentration levels were detected using a custom built laser dispersion spectrometer in a long open-path beam configuration. The instrument is driven by a chirped distributed feedback mid-infrared quantum cascade laser centered at ~1283.46 cm-1 and covers intense rotational-vibrational transitions from the fundamental ν4 band of methane. A full forward model simulating molecular absorption and dispersion profiles, as well as instrumental noise, is demonstrated. The instrument's analytical model is validated and used for quantitative instrumental optimization. The temporal evolution of atmospheric methane mixing ratios is retrieved using a fitting algorithm based on the model. Full error propagation analysis on precision gives a normalized sensitivity of ~3 ppm.m.Hz-0.5 for atmospheric methane. PMID:25607487

  10. Numerical simulation and variational data assimilation for atmospheric dispersion of pollutants

    International Nuclear Information System (INIS)

    This work has led to the development of a three-dimensional chemistry-transport model Polair3D which simulates photochemistry. Model-to-data comparison of ozone and nitrogen oxides measurements over the city of Lille in 1998 has proven its reliability at regional scale. 4-dimensional-variational data assimilation has been implemented. It relies on the adjoint model of Polair3D obtained through automatic differentiation. An application of inverse modelling of emissions over Lille city with real measurements has been performed. It has proven that the inversion of temporal parameters of nitrogen oxides emissions leads to a significant improvement of forecasts. The so-called second-order sensitivity allows the study of the sensitivity of the inversion with respect to the data assimilation system itself by computing its conditioning. This is illustrated by two test cases: short-range dispersion of radionuclides and gas-phase atmospheric chemistry characterized by a wide range of timescales. (author)

  11. Lagrangian Modeling of the Atmosphere

    Science.gov (United States)

    Schultz, Colin

    2013-08-01

    Like watching a balloon borne by the breeze, a Lagrangian model tracks a parcel of air as it flows through the atmosphere. Whether running forward or backward in time, Lagrangian models offer a powerful tool for tracking and understanding the fates, or origins, of atmospheric flows. In the AGU monograph Lagrangian Modeling of the Atmosphere, editors John Lin, Dominik Brunner, Christoph Gerbig, Andreas Stohl, Ashok Luhar, and Peter Webley explore the nuances of the modeling technique. In this interview Eos talks to Lin about the growing importance of Lagrangian modeling as the world settles on climate change mitigation strategies, the societal value of operational modeling, and how recent advances are making it possible to run these complex calculations at home.

  12. Hanford atmospheric dispersion data: 1960 through June 1967

    Energy Technology Data Exchange (ETDEWEB)

    Nickola, P.W.; Ramsdell, J.V.; Glantz, C.S.; Kerns, R.E.

    1983-11-01

    This volume presents dispersion and supporting meteorological data from experiments conducted over relatively flat terrain at Hanford, Washington from January 1960 through June 1967. The nature of the experiments, the sampling grids, and the tracer techniques used are described in the narrative portion of the document. Appendices contain the time-integrated concentrations for samplers within the plumes, summaries of the concentration distributions across the plumes, and wind and temperature profile data for each release period. 18 references, 7 figures, 3 tables.

  13. Iterative ensemble Kalman filter for atmospheric dispersion in nuclear accidents: An application to Kincaid tracer experiment.

    Science.gov (United States)

    Zhang, X L; Su, G F; Chen, J G; Raskob, W; Yuan, H Y; Huang, Q Y

    2015-10-30

    Information about atmospheric dispersion of radionuclides is vitally important for planning effective countermeasures during nuclear accidents. Results of dispersion models have high spatial and temporal resolutions, but they are not accurate enough due to the uncertain source term and the errors in meteorological data. Environmental measurements are more reliable, but they are scarce and unable to give forecasts. In this study, our newly proposed iterative ensemble Kalman filter (EnKF) data assimilation scheme is used to combine model results and environmental measurements. The system is thoroughly validated against the observations in the Kincaid tracer experiment. The initial first-guess emissions are assumed to be six magnitudes underestimated. The iterative EnKF system rapidly corrects the errors in the emission rate and wind data, thereby significantly improving the model results (>80% reduction of the normalized mean square error, r=0.71). Sensitivity tests are conducted to investigate the influence of meteorological parameters. The results indicate that the system is sensitive to boundary layer height. When the heights from the numerical weather prediction model are used, only 62.5% of reconstructed emission rates are within a factor two of the actual emissions. This increases to 87.5% when the heights derived from the on-site observations are used.

  14. Atmospheric Deposition Modeling Results

    Data.gov (United States)

    U.S. Environmental Protection Agency — This asset provides data on model results for dry and total deposition of sulfur, nitrogen and base cation species. Components include deposition velocities, dry...

  15. Kalman filtration of radiation monitoring data from atmospheric dispersion of radioactive materials

    International Nuclear Information System (INIS)

    A Kalman filter method using off-site radiation monitoring data is proposed as a tool for on-line estimation of the source term for short-range atmospheric dispersion of radioactive materials. The method is based on the Gaussian plume model, in which the plume parameters including the source term exhibit a 'random walk' process. The embedded parameters of the Kalman filter are determined through maximum-likelihood estimation making the filter essentially free of external parameters. The method is tested using both real and simulated radiation monitoring data. For simulated data, the method is shown to retrieve the embedded parameters employed in generating the data and to reconstruct the plume model parameters, including the source term. When tested against experimental radiation monitoring data the method is found accurately to uncover the known source term. (authors)

  16. Simulation of the atmospheric dispersion at local scale in the area of Cogema (la Hague) using PERLE system

    International Nuclear Information System (INIS)

    METEO-FRANCE is presently developing a new system named PERLE which permits real time evaluation of atmospheric dispersion at local scale. This system consists in a non-hydrostatic meteorological model at mezo-scale (Meso-NH) and a particular code for the dispersion of the chemically passive pollutants. As a result of several studies performed by DP/SERV/ENV at Meteo-France, two particular codes have been retained for the dispersion module of PERLE: DIFPAR (EDF) and SPRAY (Aria Technologies). In this study, the dispersion at local scale of Kr 85 in the area of the nuclear-wastes reprocessing plant COGEMA (La Hague) has been simulated with the two dispersion models, initialised with the meteorological fields provided by Meso-NH. The simulations concern the most complete sampling campaign of Kr 85 performed in this area on 18th and 19th september 2001. The evaluation the two models performances and of the PERLE system's results for this campaign has been done by using the CTA (Atmospherical Transfer Coefficient) measured values. (authors)

  17. Development and test of an evaluation protocol for heavy gas dispersion models

    NARCIS (Netherlands)

    Duijm, N.J.; Carissimo, B.; Mercer, A.; Bartholome, C.; Giesbrecht, H.

    1997-01-01

    In order to improve the quality (i.e. fitness-for-purpose) of models used to describe the atmospheric dispersion of heavy gas, an evaluation methodology has been developed and tested through a small evaluation exercise. This activity was carried out by the Heavy Gas Dispersion Expert Group, which wa

  18. Debris Dispersion Model Using Java 3D

    Science.gov (United States)

    Thirumalainambi, Rajkumar; Bardina, Jorge

    2004-01-01

    This paper describes web based simulation of Shuttle launch operations and debris dispersion. Java 3D graphics provides geometric and visual content with suitable mathematical model and behaviors of Shuttle launch. Because the model is so heterogeneous and interrelated with various factors, 3D graphics combined with physical models provides mechanisms to understand the complexity of launch and range operations. The main focus in the modeling and simulation covers orbital dynamics and range safety. Range safety areas include destruct limit lines, telemetry and tracking and population risk near range. If there is an explosion of Shuttle during launch, debris dispersion is explained. The shuttle launch and range operations in this paper are discussed based on the operations from Kennedy Space Center, Florida, USA.

  19. MARCS model atmospheres

    CERN Document Server

    Plez, Bertrand

    2008-01-01

    In this review presented at the Symposium A stellar journey in Uppsala, June 2008, I give my account of the historical development of the MARCS code from the first version published in 1975 and its premises to the 2008 grid. It is shown that the primary driver for the development team is the science that can be done with the models, and that they constantly strive to include the best possible physical data. A few preliminary comparisons of M star model spectra to spectrophotometric observations are presented. Particular results related to opacity effects are discussed. The size of errors in the spectral energy distribution (SED) and model thermal stratification are estimated for different densities of the wavelength sampling. The number of points used in the MARCS 2008 grid (108000) is large enough to ensure errors of only a few K in all models of the grid, except the optically very thin layers of metal-poor stars. Errors in SEDs may reach about 10% locally in the UV. The published sampled SEDs are thus appro...

  20. Dispersion modeling of thermal power plant emissions on stochastic space

    Science.gov (United States)

    Gorle, J. M. R.; Sambana, N. R.

    2016-05-01

    This study aims to couple a deterministic atmospheric dispersion solver based on Gaussian model with a nonintrusive stochastic model to quantify the propagation of multiple uncertainties. The nonintrusive model is based on probabilistic collocation framework. The advantage of nonintrusive nature is to retain the existing deterministic plume dispersion model without missing the accuracy in extracting the statistics of stochastic solution. The developed model is applied to analyze the SO2 emission released from coal firing unit in the second stage of the National Thermal Power Corporation (NTPC) in Dadri, India using "urban" conditions. The entire application is split into two cases, depending on the source of uncertainty. In case 1, the uncertainties in stack gas exit conditions are used to construct the stochastic space while in case 2, meteorological conditions are considered as the sources of uncertainty. Both cases develop 2D uncertain random space in which the uncertainty propagation is quantified in terms of plume rise and pollutant concentration distribution under slightly unstable atmospheric stability conditions. Starting with deterministic Gaussian plume model demonstration and its application, development of stochastic collocation model, convergence study, error analysis, and uncertainty quantification are presented in this paper.

  1. Probabilistic siting analysis of nuclear power plants emphasizing atmospheric dispersion of radioactive releases and radiation-induced health effects

    International Nuclear Information System (INIS)

    A presentation is made of probabilistic evaluation schemes for nuclear power plant siting. Effects on health attributable to ionizing radiation are reviewed, for the purpose of assessment of the numbers of the most important health effect cases in light-water reactor accidents. The atmospheric dispersion of radioactive releases from nuclear power plants is discussed, and there is presented an environmental consequence assessment model in which the radioactive releases and atmospheric dispersion of the releases are treated by the application of probabilistic methods. In the model, the environmental effects arising from exposure to radiation are expressed as cumulative probability distributions and expectation values. The probabilistic environmental consequence assessment model has been applied to nuclear power plant site evaluation, including risk-benefit and cost-benefit analyses, and the comparison of various alternative sites. (author)

  2. Atmospheric dispersal of 129iodine from nuclear fuel reprocessing facilities

    International Nuclear Information System (INIS)

    129I/127I ratios measured in meteoric water and epiphytes from the continental United States are higher than those measured in coastal seawater or surface freshwater and suggest long-range atmospheric transport of 129I from the main source for the earth's surface inventory, viz., nuclear fuel reprocessing facilities. The median ratio for 14 meteoric water samples is 2100 x 10-12, corresponding to a 129I concentration of 2.5 x 107 atoms/L, whereas 9 epiphyte samples have a median ratio of 1800 x 10-12. Calculated deposition rates of 129I in the continental United States reveal that a small but significant fraction of the atmospheric releases from the nuclear fuel reprocessing facilities at Sellafield, England, and Cap de La Hague, France, is deposited after distribution by long-range transport. The inferred dominant mode of transport is easterly, within the troposphere, mainly in the form of the organic gas methyl iodide

  3. Evaluación del desempeño de modelos de dispersión de contaminantes aplicados a cañones urbanos Evaluation of the performance of atmospheric dispersion models applied to urban street canyons

    Directory of Open Access Journals (Sweden)

    Laura E. Venegas

    2012-06-01

    Full Text Available En los cañones urbanos, frecuentemente, se presentan concentraciones de contaminantes en aire varias veces superiores a la contaminación de fondo urbana. En este trabajo, se comparan valores de concentraciones de monóxido de carbono (CO en aire medidas dentro de un cañón urbano con las estimadas mediante algunos modelos de dispersión atmosférica aplicables a procesos que se verifican en los cañones: STREET, STREET-BOX, OSPM y AEOLIUS. Se presenta la evaluación para condiciones de sotavento, barlovento y para direcciones intermedias del viento. En la comparación, se utilizaron los valores horarios de concentraciones de CO en aire medidas durante un año en el interior de un cañón urbano de Göttinger Strässe (Hannover, Alemania y en el techo de un edificio lindero, de velocidad y dirección del viento observadas en el techo del mismo edificio y de flujo de tránsito vehicular en la calle del cañón. Los resultados generados por el modelo STREET con una constante empírica k=7, subestimaron las concentraciones observadas, obteniéndose un mejor desempeño con k= 12,1. El modelo STREET-BOX es adecuado para condiciones de sotavento y direcciones intermedias, pero presenta diferencias importantes con las concentraciones observadas a barlovento. En general, los resultados aportados por los modelos OSPM y AEOLIUS fueron los que menos se apartaron de los valores observados.Air pollutant concentrations inside street canyons are usually several times background concentrations in urban areas. In this paper, carbon monoxide (CO concentrations observed in a street canyon are compared with estimated values obtained using four atmospheric dispersion models: STREET, STREET-BOX, OSPM and AEOLIUS. Results for leeward, windward and intermediate wind directions are analyzed. Data used in the model evaluation include one year of hourly CO concentrations measured inside a street canyon of Göttinger Strässe (Hannover, Germany and at the roof of a

  4. NKS NordRisk II: Atlas of long-range atmospheric dispersion and deposition of radionuclides from selected risk sites in the Northern Hemisphere

    International Nuclear Information System (INIS)

    The present atlas has been developed within the NKS/NordRisk-II project 'Nuclear risk from atmospheric dispersion in Northern Europe'. The atlas describes risks from hypothetical long-range dispersion and deposition of radionuclides from 16 nuclear risk sites on the Northern Hemisphere. The atmospheric dispersion model calculations cover a period of 30 days following each release to ensure almost complete deposition of the dispersed material. The atlas contains maps showing the total deposition and time-integrated air concentration of Cs-137 and I-131 based on three years of meteorological data spanning the climate variability associated with the North Atlantic Oscillation, and corresponding time evolution of the ensemble mean atmospheric dispersion. (Author)

  5. NKS NordRisk II: Atlas of long-range atmospheric dispersion and deposition of radionuclides from selected risk sites in the Northern Hemisphere

    Energy Technology Data Exchange (ETDEWEB)

    Smith Korsholm, U.; Havskov Soerensen, J. (Danish Meteorological Institute (DMI), Copenhagen (Denmark)); Astrup, P.; Lauritzen, B. (Technical Univ. of Denmark, Risoe National Lab. for Sustainable Energy. Radiation Research Div., Roskilde (Denmark))

    2011-04-15

    The present atlas has been developed within the NKS/NordRisk-II project 'Nuclear risk from atmospheric dispersion in Northern Europe'. The atlas describes risks from hypothetical long-range dispersion and deposition of radionuclides from 16 nuclear risk sites on the Northern Hemisphere. The atmospheric dispersion model calculations cover a period of 30 days following each release to ensure almost complete deposition of the dispersed material. The atlas contains maps showing the total deposition and time-integrated air concentration of Cs-137 and I-131 based on three years of meteorological data spanning the climate variability associated with the North Atlantic Oscillation, and corresponding time evolution of the ensemble mean atmospheric dispersion. (Author)

  6. Mesoscale constitutive modeling of magnetic dispersions.

    Science.gov (United States)

    Bhandar, Anand S; Wiest, John M

    2003-01-15

    A constitutive model for dispersions of acicular magnetic particles has been developed by modeling the particles as rigid dumbbells dispersed in a solvent. The effects of Brownian motion, anisotropic hydrodynamic drag, a steric force in the form of the Maier-Saupe potential, and, most importantly, a mean-field magnetic potential are included in the model. The development is similar to previous models for liquid-crystalline polymers. The model predicts multiple orientational states for the dispersion, and this phase behavior is described in terms of an orientational order parameter S and an average alignment parameter J; the latter is introduced because the magnetic particles have distinguishable direction due to polarity. A transition from isotropic to nematic phases at equilibrium is predicted. Multiple nematic phases-both prolate and oblate-are predicted in the presence of steady shear flow and external magnetic field parallel to the flow. The effect of increasing magnetic interparticle interactions and particle concentration is also presented. Comparisons with experimental data for the steady shear viscosity show very good agreement. PMID:16256493

  7. Can the confidence in long range atmospheric transport models be increased? The Pan-European experience of ENSEMBLE

    DEFF Research Database (Denmark)

    Galmarini, S.; Bianconi, R.; Klug, W.;

    2004-01-01

    Is atmospheric dispersion forecasting an important asset of the early-phase nuclear emergency response management? Is there a 'perfect atmospheric dispersion model'? Is there a way to make the results of dispersion models more reliable and trustworthy? While seeking to answer these questions the ...

  8. Atmospheric-dispersion parameter evaluation in the Po Valley

    Energy Technology Data Exchange (ETDEWEB)

    Bonino, G. (Turin Univ. (Italy). Ist. di Fisica; Consiglio Nazionale delle Ricerche, Turin (Italy). Lab. di Cosmo-Geofisica); Anfossi, D. (Consiglio Nazionale delle Ricerche, Turin (Italy). Lab. di Cosmo-Geofisica); Bacci, P.; Brusasca, G.; Longhetto, A. (Ente Nazionale per l' Energia Elettrica, Milan (Italy))

    Comparison of turbulent-diffusion parameters sigmasub(y) and sigmasub(z), evaluated through different experimental tests carried out in the Po Valley in the range (10/sup 2/:10/sup 4/) m downwind the source, under natural and unstable conditions, is presented and discussed. Two kinds of methods of tracer dispersion were adopted. The first one dealt with no-lift balloon diffusion in the range (10/sup 2/:10/sup 3/) m, while the second one was relative to SF/sub 6/ dispersion in the range (10/sup 3/:10/sup 4/) m. In the present paper the two sets of data are joined and a single series of best-fit curves covering the whole measured range (10/sup 2/:10/sup 4/) m is derived. The results show different behaviours for sigmasub(y) and sigmasub(z); in fact, it is possible to extrapolate sigmasub(y) trends from one set of data (SF/sub 6/) to the other one (no-lift balloons) without changing the analytical expression and the values of their coefficients. For sigmasub(z), instead, some new considerations are needed. In fact, for the unstable categories here considered (B/C and C) it is necessary to change the analytical form of the sigmasub(z) trend. This is due to the effect of convection resulting in an increase of dsigmasub(z)/d x. Finally, the exponent of the sampling time tau, in the sigmasub(y) vs. tau relationship, was found equal to 0.2, in the range (16:128) min.

  9. Modelling land surface - atmosphere interactions

    DEFF Research Database (Denmark)

    Rasmussen, Søren Højmark

    The study is investigates modelling of land surface – atmosphere interactions in context of fully coupled climatehydrological model. With a special focus of under what condition a fully coupled model system is needed. Regional climate model inter-comparison projects as ENSEMBLES have shown bias...... representation of groundwater in the hydrological model is found to important and this imply resolving the small river valleys. Because, the important shallow groundwater is found in the river valleys. If the model does not represent the shallow groundwater then the area mean surface flux calculation...

  10. Modeling and Simulation of Aerial Dispersion on Piston Dispersal Mechanism%Modeling and Simulation of Aerial Dispersion on Piston Dispersal Mechanism

    Institute of Scientific and Technical Information of China (English)

    陶如意; 王浩; 黄蓓

    2011-01-01

    For the aerial dispersing interior ballistic process and submunition exterior ballistic initial conditions of cluster munition with piston maximum travel limit, a novel model is established, and the numerical simulation is performed. The piston maximum travel limit and the effect of reaction force on carrier body are researched using the internal ballistic model. Guide tube, cluster munition rotating and submunition assembly are analyzed using the submunition initial external ballistic model. The computational results are consistent with the practical process and the experimental data, and prove the rationality of this model. The theoretical methods are presented for the construction design and dispersion analysis of piston dispersal mechanism.

  11. Adsorption modeling for macroscopic contaminant dispersal analysis

    Energy Technology Data Exchange (ETDEWEB)

    Axley, J.W.

    1990-05-01

    Two families of macroscopic adsorption models are formulated, based on fundamental principles of adsorption science and technology, that may be used for macroscopic (such as whole-building) contaminant dispersal analysis. The first family of adsorption models - the Equilibrium Adsorption (EA) Models - are based upon the simple requirement of equilibrium between adsorbent and room air. The second family - the Boundary Layer Diffusion Controlled Adsorption (BLDC) Models - add to the equilibrium requirement a boundary layer model for diffusion of the adsorbate from the room air to the adsorbent surface. Two members of each of these families are explicitly discussed, one based on the linear adsorption isotherm model and the other on the Langmuir model. The linear variants of each family are applied to model the adsorption dynamics of formaldehyde in gypsum wall board and compared to measured data.

  12. GA-based dynamical correction of dispersion coefficients in Lagrangian puff model

    Institute of Scientific and Technical Information of China (English)

    马元巍; 王德忠; 吉志龙

    2015-01-01

    In atmospheric dispersion models of nuclear accident, the dispersion coefficients were usually obtained by tracer experiment, which are constant in different atmospheric stability classifications. In fact, the atmospheric wind field is complex and unstable. The dispersion coefficients change even in the same atmospheric stability, hence the great errors brought in. According to the regulation, the air concentration of nuclides around nuclear power plant should be monitored during an accident. The monitoring data can be used to correct dispersion coefficients dynamically. The error can be minimized by correcting the coefficients. This reverse problem is nonlinear and sensitive to initial value. The property of searching the optimal solution of Genetic Algorithm (GA) is suitable for complex high-dimensional situation. In this paper, coupling with Lagrange dispersion model, GA is used to estimate the coefficients. The simulation results show that GA scheme performs well when the error is big. When the correcting process is used in the experiment data, the GA-estimated results are numerical instable. The success rate of estimation is 5%lower than the one without correction. Taking into account the continuity of the dispersion coefficient, Savitzky-Golay filter is used to smooth the estimated parameters. The success rate of estimation increases to 75.86%. This method can improve the accuracy of atmospheric dispersion simulation.

  13. Analysis of a Kalman filter based method for on-line estimation of atmospheric dispersion parameters using radiation monitoring data

    DEFF Research Database (Denmark)

    Drews, Martin; Lauritzen, Bent; Madsen, Henrik

    2005-01-01

    A Kalman filter method is discussed for on-line estimation of radioactive release and atmospheric dispersion from a time series of off-site radiation monitoring data. The method is based on a state space approach, where a stochastic system equation describes the dynamics of the plume model...... parameters, and the observables are linked to the state variables through a static measurement equation. The method is analysed for three simple state space models using experimental data obtained at a nuclear research reactor. Compared to direct measurements of the atmospheric dispersion, the Kalman filter...... estimates are found to agree well with the measured parameters, provided that the radiation measurements are spread out in the cross-wind direction. For less optimal detector placement it proves difficult to distinguish variations in the source term and plume height; yet the Kalman filter yields consistent...

  14. Utilities for high performance dispersion model PHYSIC

    Energy Technology Data Exchange (ETDEWEB)

    Yamazawa, Hiromi (Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment)

    1992-09-01

    The description and usage of the utilities for the dispersion calculation model PHYSIC were summarized. The model was developed in the study of developing high performance SPEEDI with the purpose of introducing meteorological forecast function into the environmental emergency response system. The procedure of PHYSIC calculation consists of three steps; preparation of relevant files, creation and submission of JCL, and graphic output of results. A user can carry out the above procedure with the help of the Geographical Data Processing Utility, the Model Control Utility, and the Graphic Output Utility. (author).

  15. The NET effect of dispersants - a critical review of testing and modelling of surface oil dispersion.

    Science.gov (United States)

    Zeinstra-Helfrich, Marieke; Koops, Wierd; Murk, Albertinka J

    2015-11-15

    Application of chemical dispersants or mechanical dispersion on surface oil is a trade-off between surface effects (impact of floating oil) and sub-surface effects (impact of suspended oil). Making an informed decision regarding such response, requires insight in the induced change in fate and transport of the oil. We aim to identify how natural, chemical and mechanical dispersion could be quantified in oil spill models. For each step in the dispersion process, we review available experimental data in order to identify overall trends and propose an algorithm or calculation method. Additionally, the conditions for successful mechanical and chemical dispersion are defined. Two commonly identified key parameters in surface oil dispersion are: oil properties (viscosity and presence of dispersants) and mixing energy (often wind speed). Strikingly, these parameters play a different role in several of the dispersion sub-processes. This may explain difficulties in simply relating overall dispersion effectiveness to the individual parameters. PMID:26412415

  16. Chemical modeling of exoplanet atmospheres

    CERN Document Server

    Venot, Olivia

    2014-01-01

    The past twenty years have revealed the diversity of planets that exist in the Universe. It turned out that most of exoplanets are different from the planets of our Solar System and thus, everything about them needs to be explored. Thanks to current observational technologies, we are able to determine some information about the atmospheric composition, the thermal structure and the dynamics of these exoplanets, but many questions remain still unanswered. To improve our knowledge about exoplanetary systems, more accurate observations are needed and that is why the Exoplanet Characterisation Observatory (EChO) is an essential space mission. Thanks to its large spectral coverage and high spectral resolution, EChO will provide exoplanetary spectra with an unprecedented accuracy, allowing to improve our understanding of exoplanets. In this work, we review what has been done to date concerning the chemical modeling of exoplanet atmospheres and what are the main characteristics of warm exoplanet atmospheres, which a...

  17. Iterative ensemble Kalman filter for atmospheric dispersion in nuclear accidents: An application to Kincaid tracer experiment

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, X.L.; Su, G.F.; Chen, J.G. [Institute of Public Safety Research, Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Raskob, W. [Institute for Nuclear and Energy Technologies, Karlsruhe Institute of Technology, Karlsruhe, D-76021 (Germany); Yuan, H.Y., E-mail: hy-yuan@outlook.com [Institute of Public Safety Research, Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Huang, Q.Y. [Institute of Public Safety Research, Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)

    2015-10-30

    Highlights: • We integrate the iterative EnKF method into the POLYPHEMUS platform. • We thoroughly evaluate the data assimilation system against the Kincaid dataset. • The data assimilation system substantially improves the model predictions. • More than 60% of the retrieved emissions are within a factor two of actual values. • The results reveal that the boundary layer height is the key influential factor. - Abstract: Information about atmospheric dispersion of radionuclides is vitally important for planning effective countermeasures during nuclear accidents. Results of dispersion models have high spatial and temporal resolutions, but they are not accurate enough due to the uncertain source term and the errors in meteorological data. Environmental measurements are more reliable, but they are scarce and unable to give forecasts. In this study, our newly proposed iterative ensemble Kalman filter (EnKF) data assimilation scheme is used to combine model results and environmental measurements. The system is thoroughly validated against the observations in the Kincaid tracer experiment. The initial first-guess emissions are assumed to be six magnitudes underestimated. The iterative EnKF system rapidly corrects the errors in the emission rate and wind data, thereby significantly improving the model results (>80% reduction of the normalized mean square error, r = 0.71). Sensitivity tests are conducted to investigate the influence of meteorological parameters. The results indicate that the system is sensitive to boundary layer height. When the heights from the numerical weather prediction model are used, only 62.5% of reconstructed emission rates are within a factor two of the actual emissions. This increases to 87.5% when the heights derived from the on-site observations are used.

  18. Atmospheric dispersion study with 85Kr and SF6 gas

    International Nuclear Information System (INIS)

    85Kr concentration in air around the reprocessing plant was measured when it was released from the plant stack during the hot-test operation treating PWR spent fuels. A charcoal absorption method was devised for this experiment as a rapid, simple and inexpensive technique for the measurement of 85Kr concentration at about 10-9μCi/cm3. Special air samplers were located a few kilometers from the stack and the air was collected for an hour at a flow-rate of 1.5 liters per minute. About thirty air samples were taken and analyzed for 85Kr concentration successfully. The performance of the sampling and analytical methods employed was good, although some improvements were found to be necessary. An example is that an air-collection bag should be made of ''saran'' to minim+ze leakage. Usually sulfur hexafluoride gas is used as an air-tracer in an atmospheric diffusion study: analytical procedure for determining the gas concentration down to 10-3 ppb is well established. In this experiment SF6 gas was injected into the stack during the discharge of 85Kr and the concentration in sampled air was also determined. The results show a good correlation between 85Kr and SF6 concentration in sampled air. (author)

  19. Modeling pollutant dispersion within a tornadic thunderstorm

    International Nuclear Information System (INIS)

    A three-dimensional numerical model was developed to calculate ground-level air concentration and deposition of particles entrained in a tornadic thunderstorm. The rotational characteristics of the tornadic storm are within the larger mesoscale flow of the storm system and transported with the vortex. Turbulence exchange coefficients are based on empirical values. The quasi-Lagrangian method of moments is used to model the transport of concentration within a grid cell volume. Results indicate that updrafts and downdrafts, coupled with scavenging of particles by precipitation, account for most of the material being deposited closer to the site than anticipated. Approximately 5% of the pollutant is dispersed into the stratosphere

  20. Atmospheric Dispersion of Radioactivity from Nuclear Power Plant Accidents: Global Assessment and Case Study for the Eastern Mediterranean and Middle East

    OpenAIRE

    Theodoros Christoudias; Yiannis Proestos; Jos Lelieveld

    2014-01-01

    We estimate the contamination risks from the atmospheric dispersion of radionuclides released by severe nuclear power plant accidents using the ECHAM/Modular Earth Submodel System (MESSy) atmospheric chemistry (EMAC) atmospheric chemistry-general circulation model at high resolution (50 km). We present an overview of global risks and also a case study of nuclear power plants that are currently under construction, planned and proposed in the Eastern Mediterranean and Middle East, a region pron...

  1. Atmospheric Dispersal of Bioactive Streptomyces albidoflavus Strains Among Terrestrial and Marine Environments.

    Science.gov (United States)

    Sarmiento-Vizcaíno, Aida; Braña, Alfredo F; González, Verónica; Nava, Herminio; Molina, Axayacatl; Llera, Eva; Fiedler, Hans-Peter; Rico, José M; García-Flórez, Lucía; Acuña, José L; García, Luis A; Blanco, Gloria

    2016-02-01

    Members of the Streptomyces albidoflavus clade, identified by 16S rRNA sequencing and phylogenetic analyses, are widespread among predominant terrestrial lichens (Flavoparmelia caperata and Xanthoria parietina) and diverse intertidal and subtidal marine macroalgae, brown red and green (Phylum Heterokontophyta, Rhodophyta, and Chlorophyta) from the Cantabrian Cornice. In addition to these terrestrial and coastal temperate habitats, similar strains were also found to colonize deep-sea ecosystems and were isolated mainly from gorgonian and solitary corals and other invertebrates (Phylum Cnidaria, Annelida, Echinodermata, Arthropoda, and Porifera) living up to 4700-m depth and at a temperature of 2-4 °C in the submarine Avilés Canyon. Similar strains have been also repeatedly isolated from atmospheric precipitations (rain drops, snow, and hailstone) collected in the same area throughout a year observation time. These ubiquitous strains were found to be halotolerant, psychrotolerant, and barotolerant. Bioactive compounds with diverse antibiotic and cytotoxic activities produced by these strains were identified by high-performance liquid chromatography (HPLC) and database comparison. These include antibacterials (paulomycins A and B), antifungals (maltophilins), antifungals displaying also cytotoxic activities (antimycins and 6-epialteramides), and the antitumor compound fredericamycin. A hypothetical dispersion model is here proposed to explain the biogeographical distribution of S. albidoflavus strains in terrestrial, marine, and atmospheric environments. PMID:26224165

  2. Mixing height derived from the DMI-HIRLAM NWP model, and used for ETEX dispersion modelling

    Energy Technology Data Exchange (ETDEWEB)

    Soerensen, J.H.; Rasmussen, A. [Danish Meteorological Inst., Copenhagen (Denmark)

    1997-10-01

    For atmospheric dispersion modelling it is of great significance to estimate the mixing height well. Mesoscale and long-range diffusion models using output from numerical weather prediction (NWP) models may well use NWP model profiles of wind, temperature and humidity in computation of the mixing height. This is dynamically consistent, and enables calculation of the mixing height for predicted states of the atmosphere. In autumn 1994, the European Tracer Experiment (ETEX) was carried out with the objective to validate atmospheric dispersion models. The Danish Meteorological Institute (DMI) participates in the model evaluations with the Danish Emergency Response Model of the Atmosphere (DERMA) using NWP model data from the DMI version of the High Resolution Limited Area Model (HIRLAM) as well as from the global model of the European Centre for Medium-Range Weather Forecast (ECMWF). In DERMA, calculation of mixing heights are performed based on a bulk Richardson number approach. Comparing with tracer gas measurements for the first ETEX experiment, a sensitivity study is performed for DERMA. Using DMI-HIRLAM data, the study shows that optimum values of the critical bulk Richardson number in the range 0.15-0.35 are adequate. These results are in agreement with recent mixing height verification studies against radiosonde data. The fairly large range of adequate critical values is a signature of the robustness of the method. Direct verification results against observed missing heights from operational radio-sondes released under the ETEX plume are presented. (au) 10 refs.

  3. ATMOSPHERIC DISPERSION COEFFICIENTS AND RADIOLOGICAL AND TOXICOLOGICAL EXPOSURE METHODOLOGY FOR USE IN TANK FARMS

    Energy Technology Data Exchange (ETDEWEB)

    GRIGSBY KM

    2011-04-07

    This report presents the atmospheric dispersion coefficients used in Tank Farms safety analysis. The basis equations for calculating radiological and toxicological exposures are also included. In this revision, the time averaging for toxicological consequence evaluations is clarified based on a review of DOE complex guidance and a review of tank farm chemicals.

  4. Model for Simulation Atmospheric Turbulence

    DEFF Research Database (Denmark)

    Lundtang Petersen, Erik

    1976-01-01

    A method that produces realistic simulations of atmospheric turbulence is developed and analyzed. The procedure makes use of a generalized spectral analysis, often called a proper orthogonal decomposition or the Karhunen-Loève expansion. A set of criteria, emphasizing a realistic appearance...... eigenfunctions and estimates of the distributions of the corresponding expansion coefficients. The simulation method utilizes the eigenfunction expansion procedure to produce preliminary time histories of the three velocity components simultaneously. As a final step, a spectral shaping procedure is then applied....... The method is unique in modeling the three velocity components simultaneously, and it is found that important cross-statistical features are reasonably well-behaved. It is concluded that the model provides a practical, operational simulator of atmospheric turbulence....

  5. Model of tritium dispersion by ground water

    Science.gov (United States)

    Golubev, A. V.; Mavrin, S. V.; Sten'gach, A. V.

    2000-07-01

    A three-dimensional model of ground-water contamination in the zone of a steady source of tritium is presented. The model is oriented toward long-term modeling of contamination (for up to several decades) on a large area (of up to several hundred square kilometers) where the contaminant arrives through the roof of the aquiferous stratum by infiltration. The three-dimensional equation of convective diffusion is solved numerically by the method of splitting. The convective component is calculated by the method of particles. The dispersion component of the transfer is calculated using the finite-difference method. A transformation of the vertical coordinate is introduced. A solution of the model problem is presented and an interpretation of the results is given.

  6. Plutonium explosive dispersal modeling using the MACCS2 computer code

    Energy Technology Data Exchange (ETDEWEB)

    Steele, C.M.; Wald, T.L.; Chanin, D.I.

    1998-11-01

    The purpose of this paper is to derive the necessary parameters to be used to establish a defensible methodology to perform explosive dispersal modeling of respirable plutonium using Gaussian methods. A particular code, MACCS2, has been chosen for this modeling effort due to its application of sophisticated meteorological statistical sampling in accordance with the philosophy of Nuclear Regulatory Commission (NRC) Regulatory Guide 1.145, ``Atmospheric Dispersion Models for Potential Accident Consequence Assessments at Nuclear Power Plants``. A second advantage supporting the selection of the MACCS2 code for modeling purposes is that meteorological data sets are readily available at most Department of Energy (DOE) and NRC sites. This particular MACCS2 modeling effort focuses on the calculation of respirable doses and not ground deposition. Once the necessary parameters for the MACCS2 modeling are developed and presented, the model is benchmarked against empirical test data from the Double Tracks shot of project Roller Coaster (Shreve 1965) and applied to a hypothetical plutonium explosive dispersal scenario. Further modeling with the MACCS2 code is performed to determine a defensible method of treating the effects of building structure interaction on the respirable fraction distribution as a function of height. These results are related to the Clean Slate 2 and Clean Slate 3 bunkered shots of Project Roller Coaster. Lastly a method is presented to determine the peak 99.5% sector doses on an irregular site boundary in the manner specified in NRC Regulatory Guide 1.145 (1983). Parametric analyses are performed on the major analytic assumptions in the MACCS2 model to define the potential errors that are possible in using this methodology.

  7. Plutonium explosive dispersal modeling using the MACCS2 computer code

    International Nuclear Information System (INIS)

    The purpose of this paper is to derive the necessary parameters to be used to establish a defensible methodology to perform explosive dispersal modeling of respirable plutonium using Gaussian methods. A particular code, MACCS2, has been chosen for this modeling effort due to its application of sophisticated meteorological statistical sampling in accordance with the philosophy of Nuclear Regulatory Commission (NRC) Regulatory Guide 1.145, ''Atmospheric Dispersion Models for Potential Accident Consequence Assessments at Nuclear Power Plants''. A second advantage supporting the selection of the MACCS2 code for modeling purposes is that meteorological data sets are readily available at most Department of Energy (DOE) and NRC sites. This particular MACCS2 modeling effort focuses on the calculation of respirable doses and not ground deposition. Once the necessary parameters for the MACCS2 modeling are developed and presented, the model is benchmarked against empirical test data from the Double Tracks shot of project Roller Coaster (Shreve 1965) and applied to a hypothetical plutonium explosive dispersal scenario. Further modeling with the MACCS2 code is performed to determine a defensible method of treating the effects of building structure interaction on the respirable fraction distribution as a function of height. These results are related to the Clean Slate 2 and Clean Slate 3 bunkered shots of Project Roller Coaster. Lastly a method is presented to determine the peak 99.5% sector doses on an irregular site boundary in the manner specified in NRC Regulatory Guide 1.145 (1983). Parametric analyses are performed on the major analytic assumptions in the MACCS2 model to define the potential errors that are possible in using this methodology

  8. Characterization of exoplanet atmospheres using high-dispersion spectroscopy with the E-ELT and beyond

    Directory of Open Access Journals (Sweden)

    Snellen Ignas

    2013-04-01

    Full Text Available Ground-based high-dispersion (R ∼ 100,000 spectroscopy provides unique information on exoplanet atmospheres, inaccessible from space - even using the JWST or other future space telescopes. Recent successes in transmission- and dayside spectroscopy using CRIRES on the Very Large Telescope prelude the enormous discovery potential of high-dispersion spectrographs on the E-ELT, such as METIS in the thermal infrared, and HIRES in the optical/near-infrared. This includes the orbital inclination and masses of hundred(s of non-transiting planets, line-by-line molecular band spectra, planet rotation and global wind patterns, longitudinal spectral variations, and possibly isotopologue ratios. Thinking beyond the E-ELT, we advocate that ultimately a systematic search for oxygen in atmospheres of nearby Earth-like planets can be conducted using large arrays of relatively low-cost flux collector telescopes equipped with high-dispersion spectrographs.

  9. Sensitivity of numerical dispersion modeling to explosive source parameters

    International Nuclear Information System (INIS)

    The calculation of downwind concentrations from non-traditional sources, such as explosions, provides unique challenges to dispersion models. The US Department of Energy has assigned the Atmospheric Release Advisory Capability (ARAC) at the Lawrence Livermore National Laboratory (LLNL) the task of estimating the impact of accidental radiological releases to the atmosphere anywhere in the world. Our experience includes responses to over 25 incidents in the past 16 years, and about 150 exercises a year. Examples of responses to explosive accidents include the 1980 Titan 2 missile fuel explosion near Damascus, Arkansas and the hydrogen gas explosion in the 1986 Chernobyl nuclear power plant accident. Based on judgment and experience, we frequently estimate the source geometry and the amount of toxic material aerosolized as well as its particle size distribution. To expedite our real-time response, we developed some automated algorithms and default assumptions about several potential sources. It is useful to know how well these algorithms perform against real-world measurements and how sensitive our dispersion model is to the potential range of input values. In this paper we present the algorithms we use to simulate explosive events, compare these methods with limited field data measurements, and analyze their sensitivity to input parameters. 14 refs., 7 figs., 2 tabs

  10. Relation between Dispersion Characteristics over Surfaces with Dissimilar Roughness and Atmospheric Stability, under Conditions of Equal Geostrophic Winds

    DEFF Research Database (Denmark)

    Gryning, Sven-Erik; Larsen, Søren Ejling

    1981-01-01

    A simple model was described that related the dispersion of material from ground-level sources at 2 areas, taking into account dissimilarities in the surface roughness parameter (z0) and the atmospheric stability characterized by the Monin-Obukhov length (L). The geostrophic wind speed was assumed...... that travelled a distance x; .hivin.z/L was found when z0/L and x/z0 were known. The model was reduced to 3 dimensionless parameters by merging .hivin.z/L for the 2 areas into a composite parameter. Dimensionless results from the model were illustrated for discrete values of this composite parameter....

  11. Coordination of atmospheric dispersion activities for the real-time decision support system RODOS

    International Nuclear Information System (INIS)

    This projects task has been to coordinate activities among the RODOS Atmospheric Dispersion sub-group A participants, with the overall objective of developing and integrating an atmospheric transport and dispersion module for the joint European Real-time On-line DecisiOn Support system RODOS headed by FZK (formerly KfK), Germany. The project's final goal is the establishment of a fully operational, system-integrated atmospheric transport module for the RODOS system by year 2000, capable of consistent now- and forecasting of radioactive airborne spread over all types of terrain and on all scales of interest, including in particular complex terrain and the different scales of operation, such as the local, the national and the European scale. (au)

  12. Novel applications of the dispersive optical model

    CERN Document Server

    Dickhoff, W H; Mahzoon, M H

    2016-01-01

    A review of recent developments of the dispersive optical model (DOM) is presented. Starting from the original work of Mahaux and Sartor, several necessary steps are developed and illustrated which increase the scope of the DOM allowing its interpretation as generating an experimentally constrained functional form of the nucleon self-energy. The method could therefore be renamed as the dispersive self-energy method. The aforementioned steps include the introduction of simultaneous fits of data for chains of isotopes or isotones allowing a data-driven extrapolation for the prediction of scattering cross sections and level properties in the direction of the respective drip lines. In addition, the energy domain for data was enlarged to include results up to 200 MeV where available. An important application of this work was implemented by employing these DOM potentials to the analysis of the (\\textit{d,p}) transfer reaction using the adiabatic distorted wave approximation (ADWA). We review the fully non-local DOM...

  13. The MRBT model: an analytical dispersion model in a finite mixing layer. Sensitivity analysis and validation against tracer measurements

    Science.gov (United States)

    Andretta, Massimo; Bianconi, Roberto; Flospergher, Walter; Tamponi, Matteo

    This paper describes the characteristics of the MRBT model for studying the dispersion of a pollutant in the lower atmosphere under conditions of spatial homogeneity. The MRBT is shown to be a simple and efficient model based upon a non-stationary analytical solution of the atmospheric dispersion equation in a finite mixing layer. The results of the sensitivity analysis and of validation testing, made with field measurements of tracers carried out at the Nuclear Research Centre in Karlsruhe (Germany), demonstrate the superiority of MRBT with respect to traditional Gaussian models. The model is currently implemented in FORTRAN 77 for the personal computer and is suitable for an initial assessment of short-term atmospheric dispersion with limited computing resources.

  14. Lagrangian modeling of atmospheric dispersion of radionuclides and geographical information systems as tools to support emergency planning in area of influence of nuclear complex of Angra dos Reis, RJ, Brazil; Modelagem Lagrangeana da dispersao atmoferica de radionuclideos e sistemas de informacao geografica como ferramentas de suporte ao planejamento de emergencia na area de influencia do complexo nuclear de Angra dos Reis, RJ

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Corbiniano

    2013-07-01

    Industrial accidents generally endanger structures and the set of environmental influence area where the enterprises are located, especially when affected by atmospheric dispersion of their pollutants, whose concern with the evacuation of the population is the main goal in emergency situations. Considering the nuclear complex Angra dos Reis - RJ, based on computer modeling analysis of the mechanisms of pollutant dispersion in conjunction with geographic information systems were developed. Thus, information about the dispersion of radionuclides - from simulations performed on the HYSPLIT; meteorological data (direction, intensity and calm on the wind regime and analysis of the wind field in the region using WRF), occurrence of landslides and data on the environmental study area were integrated into a GIS database using ArcGIS platform. Aiming at the identification and definition of escape routes in case of evacuation from accidental events in CNAAA, the results point solutions for long-term planning, based on weather and landslides, and short-term, supported by simulations of the dispersion radionuclides, in order to support actions that assist local emergency planning. (author)

  15. Atmospheric dispersion analysis in preparing permit applications for the new nuclear power plants in the United States

    International Nuclear Information System (INIS)

    Nuclear power generation has become an increasingly attractive alternative in the United States (U.S.) power market due to several factors: growing demand for electric power, increasing global competition for fossil fuels, concern over greenhouse gas emissions and their potential impact on global warming, and the desire for energy independence. Currently there are more than 19 utilities and nuclear energy groups in the U.S. have announced plans for new plants to submit permit applications of Early Site Permits (ESP) and/or Combined Licenses (COL). In support of the permit applications, the following assessments are required: potential dispersion of radioactive material from, and the radioactive consequences of, design-basis accidents to aid in evaluating the acceptability of a site and the adequacy of engineered safety features for a nuclear power plants; maximum potential annual radiation dose to the public resulting from the routine release of radioactive materials in gaseous effluent; habitability of the control room during postulated design-basis radiological accidents and hazardous chemical releases; near-real-time atmospheric transport and diffusion estimates immediately following an accidental releases of airborne radioactive material to provide input to the evaluation of the consequences of radiological releases to the atmosphere and to aid in the implementation of emergency response decisions; the potential dispersion of radioactive materials from, and the radiological consequences of, a spectrum of accidents to aid in evaluating the environmental risk posed by a nuclear power plant; and the non-radiological related environmental effects, such as fogging, icing, and salt drift from cooling towers or ponds, to aid in evaluating the environmental impact of a nuclear power plant. The paper presents an overview of dispersion modeling approaches/techniques. Common regulatory conformance issues, particularly regarding (1) available computer modeling tools

  16. Prime focus wide-field corrector designs with lossless atmospheric dispersion correction

    Energy Technology Data Exchange (ETDEWEB)

    Saunders, Will [Australian Astron. Observ.; Gillingham, Peter [Australian Astron. Observ.; Smith, Greg [Australian Astron. Observ.; Kent, Steve [Fermilab; Doel, Peter [University Coll. London

    2014-07-18

    Wide-Field Corrector designs are presented for the Blanco and Mayall telescopes, the CFHT and the AAT. The designs are Terezibh-style, with 5 or 6 lenses, and modest negative optical power. They have 2.2-3 degree fields of view, with curved and telecentric focal surfaces suitable for fiber spectroscopy. Some variants also allow wide-field imaging, by changing the last WFC element. Apart from the adaptation of the Terebizh design for spectroscopy, the key feature is a new concept for a 'Compensating Lateral Atmospheric Dispersion Corrector', with two of the lenses being movable laterally by small amounts. This provides excellent atmospheric dispersion correction, without any additional surfaces or absorption. A novel and simple mechanism for providing the required lens motions is proposed, which requires just 3 linear actuators for each of the two moving lenses.

  17. Modelling Aerosol Dispersion in Urban Street Canyons

    Science.gov (United States)

    Tay, B. K.; Jones, D. P.; Gallagher, M. W.; McFiggans, G. B.; Watkins, A. P.

    2009-04-01

    Flow patterns within an urban street canyon are influenced by various micrometeorological factors. It also represents an environment where pollutants such as aerosols accumulate to high levels due to high volumes of traffic. As adverse health effects are being attributed to exposure to aerosols, an investigation of the dispersion of aerosols within such environments is of growing importance. In particular, one is concerned with the vertical structure of the aerosol concentration, the ventilation characteristics of the street canyon and the influence of aerosol microphysical processes. Due to the inherent heterogeneity of the aerosol concentrations within the street canyon and the lack of spatial resolution of measurement campaigns, these issues are an on-going debate. Therefore, a modelling tool is required to represent aerosol dispersion patterns to provide insights to results of past measurement campaigns. Computational Fluid Dynamics (CFD) models are able to predict detailed airflow patterns within urban geometries. This capability may be further extended to include aerosol dispersion, by an Euler-Euler multiphase approach. To facilitate the investigation, a two-dimensional, multiphase CFD tool coupled with the k-epsilon turbulence model and with the capability of modelling mixed convection flow regimes arising from both wind driven flows and buoyancy effects from heated walls was developed. Assuming wind blowing perpendicularly to the canyon axis and treating aerosols as a passive scalar, an attempt will be made to assess the sensitivities of aerosol vertical structure and ventilation characteristics to the various flow conditions. Numerical studies were performed using an idealized 10m by 10m canyon to represent a regular canyon and 10m by 5m to represent a deep one. An aerosol emission source was assigned on the centerline of the canyon to represent exhaust emissions. The vertical structure of the aerosols would inform future directives regarding the

  18. Uncertainty analyses for the atmospheric dispersion submodule of UFOMOD with emphasis on parameter correlations

    International Nuclear Information System (INIS)

    Special emphasis is put on some helpful theoretical investigations concerning: 1. different types of correlation between uncertain model parameters; 2. test procedures to find out the most sensitive uncertain model parameters; 3. the percentage contribution of parameter variations to changes in consequence values. For the mentioned submodule of the new program system UFOMOD version NE 87/1, the most important parameters are stable in their rankings regardless of the underlying distributions (predefined by experts or all uniformly distributed, respectively). For the less important parameters the values of the sensitivity measures (PRCC values) vary for predefined or uniform distributions, respectively. But even then in most cases the ranking is the same. Increasing sample sizes (n = 80, 100) lead to more precision in sensitivity calculations, i.e. lead to a decrease of the critical 'white noise level' (garbage level) of absolute PRCC values. R2-values (coefficients of determination) in conjunction with the corresponding PRCC values visualize the percentage contribution of each uncertain model parameter (or groups of uncertain parameters) to uncertainty in consequences. This is important, because a large absolute PRCC value is not in every case an indication for a considerable amount of responsibility for uncertainty in consequences. The restriction to pure model parameters and revised parameter variations in the atmospheric dispersion and deposition submodule of the new UFOMOD code system lead to significantly smaller uncertainty bands than for the old UFOMOD/B3 code. Variations in deposition velocities and the mixing height parameters play the most important role for uncertainties in the activity concentration values. (orig./HP)

  19. Field Studies for Validation of Urban Dispersion Models - Current Status and Research Needs

    Science.gov (United States)

    Allwine, J.

    2007-12-01

    Urban dispersion models are important tools in addressing consequences from potential releases of harmful airborne materials in urban areas. These models are used by emergency management, law enforcement, and intelligence personnel to effectively plan for and respond to potential terrorist attacks and accidents. Field studies are vitally important for improving and validating these urban dispersion models which are used to simulate contaminant dispersion in and around cities. Over the past decade, three major urban field studies have been designed and conducted in the United States. The primary objectives of these studies have been to advance the state-of-science of understanding and modeling atmospheric flows and dispersion in and around cities, and to provide field observation for validation of urban dispersion models. The three major field studies (Salt Lake City, October 2000; Oklahoma City, July 2003; and New York City, August 2005) were conducted in cities of different sizes, in different geographic regions and during different times of the year. The tracer and meteorological data from these three field campaigns provide a rich dataset for validation of urban dispersion models over a range of conditions. The status and uses of the three urban dispersion datasets will be summarized, followed by a discussion of the current observational gaps and research needs in characterizing specific urban dispersion processes, such as outdoor-indoor coupling and outdoor-subway coupling.

  20. Development of a code to simulate dispersion of atmospheric released tritium gas in the environmental media and to evaluate doses. TRIDOSE

    Energy Technology Data Exchange (ETDEWEB)

    Murata, Mikio [Nuclear Engineering Co., Ltd., Hitachi, Ibaraki (Japan); Noguchi, Hiroshi; Yokoyama, Sumi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2000-11-01

    A computer code (TRIDOSE) was developed to assess the environmental impact of atmospheric released tritium gas (T{sub 2}) from nuclear fusion related facilities. The TRIDOSE simulates dispersion of T{sub 2} and resultant HTO in the atmosphere, land, plant, water and foods in the environment, and evaluates contamination concentrations in the media and exposure doses. A part of the mathematical models in TRIDOSE were verified by comparison of the calculation with the results of the short range (400 m) dispersion experiment of HT gas performed in Canada postulating a short-time (30 minutes) accidental release. (author)

  1. Optimization of wind speed on dispersion of pollutants using coupled receptor and dispersion model

    Indian Academy of Sciences (India)

    N Anu; S Rangabhashiyam; Rahul Antony; N Selvaraju

    2015-08-01

    Air pollutants emission from various source categories can be quantified through mass balance (receptor model) techniques, multivariate data analysis and dispersion model. The composition of particulate matter from various emission points (emission inventory) and the massive analysis of the composition in the collected samples from various locations (receptor) are used to estimate quantitative source contribution through receptor models. In dispersion model, on the other hand the emission rates (g/m3) from various sources together with particle size, stack height, topography, meteorological conditions (temperature, humidity, wind speed and directions, etc.) will affect the pollutant concentration at a point or in a region. The parameters used in dispersion model are not considering in receptor models but have been affecting indirectly as difference concentration at various receptor locations. These differences are attributed and possible erroneous results can be viewed through coupled receptor-dispersion model analysis. The current research work proposed a coupled receptor-dispersion model to reduce the difference between predicted concentrations through optimized wind velocity used in dispersion model. The converged wind velocities for various error percentages (10%, 40%, 60% and 80%) in receptor concentration have been obtained with corresponding increase in the error. The proposed combined approaches help to reconcile the differences arise when the two models used in an individual mode.

  2. CFD analysis of atmospheric dispersion in a large terrain of Kakrapar atomic power station in presence of structural buildings

    International Nuclear Information System (INIS)

    The work presents a computational fluid dynamics (CFD) calculation to investigate the dispersion of SF6 over terrain of Kakrapar nuclear power plant using the actual meteorological data. Three-dimensional, transient simulations have been carried out using CFD code PHOENICS. The CFD calculation covers a domain of 3.2 km X 3.2 km in plan and 0.5 km in height. Atmospheric dispersion in presence of the structures like Reactor Building, Natural Draft Cooling Tower and Turbine Building has been studied. The SF6 was released from the stack at a height of 100 m. SF6 released was considered for 2 hours duration at a rate of 1 gm/sec. This model was used to simulate the transport of SF6 for 6 hours. The ground level concentration of SF6 was monitored

  3. Final Report for the Joint Urban 2003 Atmospheric Dispersion Study in Oklahoma City: Lawrence Livermore National Laboratory participation

    Energy Technology Data Exchange (ETDEWEB)

    Leach, M J

    2005-10-12

    The Joint Urban 2003 (JU2003) field study was designed to collect meteorological and tracer data resolving atmospheric dispersion at scales-of-motion ranging from flows in and around a single city block, in and around several blocks in the downtown Central Business District (CBD), and into the suburban Oklahoma City area a few km from the CBD. Indoor tracer and flow measurements within four downtown study buildings were also made in conjunction with detailed outdoor measurements investigating the outdoor-indoor exchange rates and mechanisms. The movement of tracer within the study buildings was also studied. The data from the field experiment is being used to evaluate models that are being developed for predicting dispersion of contaminants in urban areas. These models may be fast-response models based on semi-empirical algorithms that are used in real-time emergencies, or highly sophisticated computational fluid dynamics models that resolve individual building faces and crevices. The data from the field experiment, together with the models, can then be used to develop other advanced tools that are especially valuable in the efforts to thwart terrorists. These include tools for finding location and characteristics of a contaminant source; tools that can be used for real-time response or for forensic investigation. The tools will make use of monitoring networks for biological agents that are being established in several sensitive cities throughout the nation. This major urban study was conducted beginning June 28 and ending July 31, 2003. It included several integrated scientific components necessary to describe and understand the physical processes governing dispersion within and surrounding an urban area and into and within building environments. The components included characterizing: (1) the urban boundary layer and the development of the urban boundary layer within the atmospheric boundary layer, (2) the flows within and downwind of the tall-building core, (3

  4. Dispersive infrared spectroscopy measurements of atmospheric CO{sub 2} using a Fabry–Pérot interferometer sensor

    Energy Technology Data Exchange (ETDEWEB)

    Chan, K.L. [School of Energy and Environment, City University of Hong Kong (Hong Kong); Ning, Z., E-mail: zhining@cityu.edu.hk [School of Energy and Environment, City University of Hong Kong (Hong Kong); Guy Carpenter Climate Change Centre, City University of Hong Kong (Hong Kong); Westerdahl, D. [Ability R and D Energy Research Centre, City University of Hong Kong (Hong Kong); Wong, K.C. [School of Energy and Environment, City University of Hong Kong (Hong Kong); Sun, Y.W. [Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei (China); Hartl, A. [School of Energy and Environment, City University of Hong Kong (Hong Kong); Wenig, M.O. [Meteorological Institute, Ludwig-Maximilians-Universität Munich (Germany)

    2014-02-01

    In this paper, we present the first dispersive infrared spectroscopic (DIRS) measurement of atmospheric carbon dioxide (CO{sub 2}) using a new scanning Fabry–Pérot interferometer (FPI) sensor. The sensor measures the optical spectra in the mid infrared (3900 nm to 5220 nm) wavelength range with full width half maximum (FWHM) spectral resolution of 78.8 nm at the CO{sub 2} absorption band (∼ 4280 nm) and sampling resolution of 20 nm. The CO{sub 2} concentration is determined from the measured optical absorption spectra by fitting it to the CO{sub 2} reference spectrum. Interference from other major absorbers in the same wavelength range, e.g., carbon monoxide (CO) and water vapor (H{sub 2}O), was taken out by including their reference spectra in the fit as well. The detailed descriptions of the instrumental setup, the retrieval procedure, a modeling study for error analysis as well as laboratory validation using standard gas concentrations are presented. An iterative algorithm to account for the non-linear response of the fit function to the absorption cross sections due to the broad instrument function was developed and tested. A modeling study of the retrieval algorithm showed that errors due to instrument noise can be considerably reduced by using the dispersive spectral information in the retrieval. The mean measurement error of the prototype DIRS CO{sub 2} measurement for 1 minute averaged data is about ± 2.5 ppmv, and down to ± 0.8 ppmv for 10 minute averaged data. A field test of atmospheric CO{sub 2} measurements were carried out in an urban site in Hong Kong for a month and compared to a commercial non-dispersive infrared (NDIR) CO{sub 2} analyzer. 10 minute averaged data shows good agreement between the DIRS and NDIR measurements with Pearson correlation coefficient (R) of 0.99. This new method offers an alternative approach of atmospheric CO{sub 2} measurement featuring high accuracy, correction of non-linear absorption and interference of water

  5. Advantages of numerical atmospheric dispersion calculations for estimating dispersal and combination effects of stack releases from the nuclear industry

    International Nuclear Information System (INIS)

    An estimation of environmental pollution calculated using the idealized Gaussian distribution model to describe processes of atmospheric diffusion suffers from restrictions in the model, i.e. it assumes stationary homogeneous conditions in the atmosphere, a parallel mean wind flow with no (or at most linear) velocity shear, and constant turbulence characteristics within the plume. These assumptions are oversimplifications: for instance topographic effects, wind shear, time-dependent wind variations and the case of strong local interactions of the pollutant with other components in the atmosphere (e.g. fog, smog, rain, or other pollutant plumes) are ignored. Previous attempts to overcome the disadvantages using a purely numerical evaluation of the differential equations describing the transport, diffusion and any reactions of the pollutants in the atmosphere were unsuccessful, since 'artificial diffusion' effects were observed that led to unacceptable errors when great distances or long times were considered. At present, the best method of solving this problem appears to be the use of a combined Eulerian-Lagrangian numerical approach, called the particle-in-cell method, which was developed in the USA. The method has been tested successfully by making comparisons with typical Gaussian calculations over long time intervals or large distances: it was also applied to several actual transport problems involving complex topographies with wind variations in time, and to the effects of chemical reactions and local rainfall. This method, avoiding the undue simplification of the Gaussian calculation and the inherent fictitious diffusion patterns of the purely numerical evaluation seems to be particularly suited to solving atmospheric pollution transport problems under complex conditions that may occur in the neighbourhood of large nuclear power stations. (author)

  6. Analysis of a Kalman filter based method for on-line estimation of atmospheric dispersion parameters using radiation monitoring data

    International Nuclear Information System (INIS)

    A Kalman filter method is discussed for on-line estimation of radioactive release and atmospheric dispersion from a time series of off-site radiation monitoring data. The method is based on a state space approach, where a stochastic system equation describes the dynamics of the plume model parameters, and the observables are linked to the state variables through a static measurement equation. The method is analysed for three simple state space models using experimental data obtained at a nuclear research reactor. Compared to direct measurements of the atmospheric dispersion, the Kalman filter estimates are found to agree well with the measured parameters, provided that the radiation measurements are spread out in the cross-wind direction. For less optimal detector placement it proves difficult to distinguish variations in the source term and plume height; yet the Kalman filter yields consistent parameter estimates with large associated uncertainties. Improved source term assessment results, when independent estimates of the plume height can be used. Perspectives for using the method in the context of nuclear emergency management are discussed, and possible extensions to the present modelling scheme are outlined, to account for realistic accident scenarios. (authors)

  7. Atmospheric discharge and dispersion of radionuclides during the Fukushima Dai-ichi Nuclear Power Plant accident, 2; Verification of the source term and analysis of regional-scale atmospheric dispersion

    OpenAIRE

    寺田 宏明; 堅田 元喜; 茅野 政道; 永井 晴康

    2012-01-01

    Regional-scale atmospheric dispersion simulations were carried out to verify source term of 131I and 137Cs estimated by our previous studies and analyze the atmospheric dispersion during the Fukushima Dai-ichi Nuclear Power Plant accident with measurements of daily and monthly surface depositions over land in Eastern Japan from March 12 to April 30, 2011. The prediction accuracy of daily surface deposition by using the refined source term was mostly within a factor of 10 without apparent bias...

  8. Comparison of different estimation methods of accident atmospheric dispersion factors for a representative inland nuclear power plant

    International Nuclear Information System (INIS)

    The applicability of atmospheric diffusion models in complex terrains and low wind speed conditions was discussed in this paper. The accident atmospheric dispersion factors (ATFs) of Taohuajiang nuclear power plant were calculated by using two methods: the probabilistic method recommended by the U.S. Nuclear regulatory Commission (NRC) and the three dimensional objective diagnostic wind field model coupled with Lagrangian trajectory puff model to simulate the 8760 hourly emissions of radioactive nuclides. The results indicate that the maximum hourly accident ATFs calculated by the probabilistic method are conservative in exclusion area boundary (EAB). However, in some directions, accident ATFs calculated using probabilistic method is smaller than that using Lagrangian puff model, as well as some accident ATFs in remote sectors are larger than those in close sectors. Moreover, results calculated by probabilistic method are smaller in long-term release situation. Therefore, accident ATFs obtained according to the regulatory guides may not conservative in some cases, and atmospheric diffusion model should be selected carefully when a nuclear plant is located at a site with complex environmental conditions. (authors)

  9. Applicability of an integrated plume rise model for the dispersion from wild-land fires

    OpenAIRE

    J. Kukkonen; J. Nikmo; Sofiev, M.; Riikonen, K.; T. Petäjä; A. Virkkula; J. Levula; S. Schobesberger; D. M. Webber

    2014-01-01

    We have presented an overview of a mathematical model, BUOYANT, that was originally designed for the evaluation of the dispersion of buoyant plumes originated from major warehouse fires. The model addresses the variations of the cross-plume integrated properties of a buoyant plume in the presence of a vertically varying atmosphere. The model also includes a treatment for a rising buoyant plume interacting with an inversion layer. We have compared the model p...

  10. Applicability of an integrated plume rise model for the dispersion from wild-land fires

    OpenAIRE

    J. Kukkonen; J. Nikmo; Sofiev, M.; Riikonen, K.; T. Petäjä; A. Virkkula; J. Levula; S. Schobesberger; D. M. Webber

    2014-01-01

    We have presented an overview of a mathematical model, BUOYANT, that was originally designed for the evaluation of the dispersion of buoyant plumes originated from major warehouse fires. The model addresses the variations of the cross-plume integrated properties of a buoyant plume in the presence of a vertically varying atmosphere. The model also includes a treatment for a rising buoyant plume interacting with an inversion layer. We have compared the model predictions with t...

  11. Using Atmospheric Dispersion Theory to Inform the Design of a Short-lived Radioactive Particle Release Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Rishel, Jeremy P.; Keillor, Martin E.; Arrigo, Leah M.; Baciak, James E.; Detwiler, Rebecca S.; Kernan, Warnick J.; Kirkham, Randy R.; Milbrath, Brian D.; Seifert, Allen; Seifert, Carolyn E.; Smart, John E.

    2016-05-01

    Atmospheric dispersion theory can be used to predict ground deposition of particulates downwind of a radionuclide release. This paper utilizes standard formulations found in Gaussian plume models to inform the design of an experimental release of short-lived radioactive particles into the atmosphere. Specifically, a source depletion algorithm is used to determine the optimum particle size and release height that maximizes the near-field deposition while minimizing the both the required source activity and the fraction of activity lost to long-distance transport. The purpose of the release is to provide a realistic deposition pattern that might be observed downwind of a small-scale vent from an underground nuclear explosion. The deposition field will be used, in part, to investigate several techniques of gamma radiation survey and spectrometry that could be utilized by an On-Site Inspection team under the verification regime of the Comprehensive Nuclear-Test-Ban Treaty.

  12. Multilevel modelling of dispersed multiphase flows

    OpenAIRE

    Kuipers, J. A. M.

    2000-01-01

    Dispersed multiphase flows are frequently encountered in a variety of industrially important processes in the petroleum, chemical, metallurgical and energy industries. Scale-up of equipment involving dispersed multiphase flows is quite difficult which is mainly due to the inherent complexity of the prevailing flow phenomena (formation of bubbles and clusters in gas-particle flows). Especially during the last decade significant research efforts have been made in both academic and industrial re...

  13. Air Dispersion Modeling for Building 3026C/D Demolition

    Energy Technology Data Exchange (ETDEWEB)

    Ward, Richard C [ORNL; Sjoreen, Andrea L [ORNL; Eckerman, Keith F [ORNL

    2010-06-01

    This report presents estimates of dispersion coefficients and effective dose for potential air dispersion scenarios of uncontrolled releases from Oak Ridge National Laboratory (ORNL) buildings 3026C, 3026D, and 3140 prior to or during the demolition of the 3026 Complex. The Environmental Protection Agency (EPA) AERMOD system1-6 was used to compute these estimates. AERMOD stands for AERMIC Model, where AERMIC is the American Meteorological Society-EPA Regulatory Model Improvement Committee. Five source locations (three in building 3026D and one each in building 3026C and the filter house 3140) and associated source characteristics were determined with the customer. In addition, the area of study was determined and building footprints and intake locations of air-handling systems were obtained. In addition to the air intakes, receptor sites consisting of ground level locations on four polar grids (50 m, 100 m, 200 m, and 500 m) and two intersecting lines of points (50 m separation), corresponding to sidewalks along Central Avenue and Fifth Street. Three years of meteorological data (2006 2008) were used each consisting of three datasets: 1) National Weather Service data; 2) upper air data for the Knoxville-Oak Ridge area; and 3) local weather data from Tower C (10 m, 30 m and 100 m) on the ORNL reservation. Annual average air concentration, highest 1 h average and highest 3 h average air concentrations were computed using AERMOD for the five source locations for the three years of meteorological data. The highest 1 h average air concentrations were converted to dispersion coefficients to characterize the atmospheric dispersion as the customer was interested in the most significant response and the highest 1 h average data reflects the best time-averaged values available from the AERMOD code. Results are presented in tabular and graphical form. The results for dose were obtained using radionuclide activities for each of the buildings provided by the customer.7

  14. Modelo matemático de dispersão de poluentes na atmosfera: um instrumento técnico para a gestão ambiental Mathematical model of pollutants dispersion in the atmosphere: an instrument technique to environmental management

    Directory of Open Access Journals (Sweden)

    Davidson Moreira

    2004-12-01

    Full Text Available Os modelos matemáticos de dispersão de poluentes na atmosfera representam um instrumento técnico importante, seja para o conhecimento do estado do ambiente, unidos à rede de monitoramento, seja para a gestão ambiental. Neste trabalho são evidenciadas as caraterísticas operacionais e teóricas dos modelos. São introduzidos os modelos de nova geração que podem representar diretamente a turbulência atmosférica através do valor do comprimento de Monin-Obukhov e da velocidade de atrito. Além disso, salienta-se que uma correta utilização dos modelos de transporte e difusão na atmosfera dependem de um estudo sobre suas capacidades de representarem corretamente situações reais confrontando os valores calculados dos modelos com observações experimentais. É aprofundado em particular, visto a grande atualidade do fenômeno, a utilização dos modelos matemáticos de dispersão na gestão da qualidade do ar em ambiente urbano.The mathematical models of pollutant dispersion in the atmosphere represent an important technical instrument, as for the knowledge of the state of the atmosphere, united to the monitoring net, as for the environmental administration. In this work the operational and theoretical characteristics of air pollution models are evidenced. Models of new generation that can represent the atmospheric turbulence directly through the value of the Monin-Obukhov length and of the friction velocity are introduced. Besides, it is pointed out that a correct use of the transport and diffusion models in the atmosphere depends of a study about their capacities of representing real situations confronting the calculated values of the models with experimental observations. It is deepened in matter, seen the great present time of the phenomenon, the use of the mathematical models of dispersion in the management of the air quality in urban environment.

  15. Models of Pluto's upper atmosphere

    International Nuclear Information System (INIS)

    Best guesses as to the thermal structure and composition of Pluto's atmosphere have led to speculations of substantial loss rates (∼1028 s-1) of methane from the planet over cosmogonic time scales. Results from recent stellar occultation measurements, and using a Parker-type hydrodynamic calculation, show that the loss rates may actually be lower by as much as a factor ∼5, depending upon the efficiency of heating of the atmosphere via the absorption of solar EUV and upon the true atmospheric composition, if the thermal structure of the upper atmosphere is properly taken into account. The loss rate may even be less (by another factor ∼10) if there is minimal heating of the upper atmosphere

  16. Dispersion modelling approaches for near road applications involving noise barriers

    Science.gov (United States)

    The talk will present comparisons with two datasets of the barrier algorithms implemented in two different dispersion models: US EPA’s R-LINE (a research dispersion modelling tool under development by the US EPA’s Office of Research and Development) and CERC’s A...

  17. Dispersion model computations of urban air pollution in Espoo, Finland

    Energy Technology Data Exchange (ETDEWEB)

    Valkonen, E.; Haerkoenen, J.; Kukkonen, J.; Rantakrans, E.; Jalkanen, L.

    1997-12-31

    This report presents the numerical results of air quality studies of the city of Espoo in southern Finland. This city is one of the four cities in the Helsinki metropolitan area, having a total population of 850 000. A thorough emission inventory was made of both mobile and stationary sources in the Helsinki metropolitan area. The atmospheric dispersion was evaluated using an urban dispersion modelling system, including a Gaussian multiple-source plume model and a meteorological pre-processing model. The hourly time series of CO, NO{sub 2} and SO{sub 2} concentrations were predicted, using the emissions and meteorological data for the year 1990. The predicted results show a clear decrease in the yearly mean concentrations from southeast to northwest. This is due in part to the denser traffic in the southern parts of Espoo, and in part to pollution from the neighbouring cities of Helsinki and Vantaa, located east of Espoo. The statistical concentration parameters found for Espoo were lower than the old national air quality guidelines (1984); however, some occurrences of above-threshold values were found for NO{sub 2} in terms of the new guidelines (1996). The contribution of traffic to the total concentrations varies spatially from 30 to 90 % for NO{sub 2} from 1 to 65 % for SO{sub 2} while for CO it is nearly 100 %. The concentrations database will be further utilised to analyse the influence of urban air pollution on the health of children attending selected day nurseries in Espoo. The results of this study can also be applied in traffic and city planning. In future work the results will also be compared with data from the urban measurement network of the Helsinki Metropolitan Area Council. (orig.) 19 refs.

  18. Dispersion analysis with inverse dielectric function modelling.

    Science.gov (United States)

    Mayerhöfer, Thomas G; Ivanovski, Vladimir; Popp, Jürgen

    2016-11-01

    We investigate how dispersion analysis can profit from the use of a Lorentz-type description of the inverse dielectric function. In particular at higher angles of incidence, reflectance spectra using p-polarized light are dominated by bands from modes that have their transition moments perpendicular to the surface. Accordingly, the spectra increasingly resemble inverse dielectric functions. A corresponding description can therefore eliminate the complex dependencies of the dispersion parameters, allow their determination and facilitate a more accurate description of the optical properties of single crystals. PMID:27294550

  19. The CIFIST 3D model atmosphere grid

    CERN Document Server

    Ludwig, H -G; Steffen, M; Freytag, B; Bonifacio, P

    2009-01-01

    Grids of stellar atmosphere models and associated synthetic spectra are numerical products which have a large impact in astronomy due to their ubiquitous application in the interpretation of radiation from individual stars and stellar populations. 3D model atmospheres are now on the verge of becoming generally available for a wide range of stellar atmospheric parameters. We report on efforts to develop a grid of 3D model atmospheres for late-type stars within the CIFIST Team at Paris Observatory. The substantial demands in computational and human labor for the model production and post-processing render this apparently mundane task a challenging logistic exercise. At the moment the CIFIST grid comprises 77 3D model atmospheres with emphasis on dwarfs of solar and sub-solar metallicities. While the model production is still ongoing, first applications are already worked upon by the CIFIST Team and collaborators.

  20. Ship plume dispersion rates in convective boundary layers for chemistry models

    Directory of Open Access Journals (Sweden)

    F. Chosson

    2008-08-01

    Full Text Available Detailed ship plume simulations in various convective boundary layer situations have been performed using a Lagrangian Dispersion Model driven by a Large Eddy Simulation Model. The simulations focus on the early stage (1–2 h of plume dispersion regime and take into account the effects of plume rise on dispersion. Results are presented in an attempt to provide to atmospheric chemistry modellers a realistic description of characteristic dispersion impact on exhaust ship plume chemistry. Plume dispersion simulations are used to derive analytical dilution rate functions. Even though results exhibit striking effects of plume rise parameter on dispersion patterns, it is shown that initial buoyancy fluxes at ship stack have a minor effect on plume dilution rate. After initial high dispersion regimes a simple characteristic dilution time scale can be used to parameterize the subgrid plume dilution effect in large-scale chemistry models. The results show that this parameter is directly related to the typical turn-over time scale of the convective boundary layer.

  1. Viscosity model of high-viscosity dispersing system

    Institute of Scientific and Technical Information of China (English)

    魏先福; 王娜; 黄蓓青; 孙承博

    2008-01-01

    High-viscosity dispersing system is formed by dispersing the solid particles in the high-viscosity continuous medium.It is very easy to form the three-dimensional network structure for solid particles in the system and the rheology behavior becomes complicated.The apparent viscosity of this dispersing system always has the connection with the volume ratio and the shear rate.In order to discuss the rheology behavior and put up the viscosity model,the suspension of silicon dioxide and silicon oil were prepared.Through testing the viscosity,the solid concentration and the shear rate,the effects of the ratio and the shear rate on viscosity was analyzed,the model of the high-viscosity dispersing system was designed and the model with the printing ink were validated.The experiment results show that the model is applicable to the high-viscosity dispersing systems.

  2. Modeling CO2 air dispersion from gas driven lake eruptions

    Science.gov (United States)

    Chiodini, Giovanni; Costa, Antonio; Rouwet, Dmitri; Tassi, Franco

    2016-04-01

    The most tragic event of gas driven lake eruption occurred at Lake Nyos (Cameroon) on 21 August 1986, when a dense cloud of CO2 suffocated more than 1700 people and an uncounted number of animals in just one night. The event stimulated a series of researches aimed to understand gas origins, gas release mechanisms and strategies for gas hazard mitigation. Very few studies have been carried out for describing the transport of dense CO2 clouds in the atmosphere. Although from a theoretical point of view, gas dispersion can be fully studied by solving the complete equations system for mass, momentum and energy transport, in actual practice, different simplified models able to describe only specific phases or aspects have to be used. In order to simulate dispersion of a heavy gas and to assess the consequent hazard we used a model based on a shallow layer approach (TWODEE2). This technique which uses depth-averaged variables to describe the flow behavior of dense gas over complex topography represents a good compromise between the complexity of computational fluid dynamic models and the simpler integral models. Recently the model has been applied for simulating CO2 dispersion from natural gas emissions in Central Italy. The results have shown how the dispersion pattern is strongly affected by the intensity of gas release, the topography and the ambient wind speed. Here for the first time we applied TWODEE2 code to simulate the dispersion of the large CO2 clouds released by limnic eruptions. An application concerns the case of the 1986 event at lake Nyos. Some difficulties for the simulations were related to the lack of quantitative information: gas flux estimations are not well constrained, meteorological conditions are only qualitatively known, the digital model of the terrain is of poor quality. Different scenarios were taken into account in order to reproduce the qualitative observations available for such episode. The observations regard mainly the effects of gas on

  3. Performance Engineering in the Community Atmosphere Model

    Energy Technology Data Exchange (ETDEWEB)

    Worley, P; Mirin, A; Drake, J; Sawyer, W

    2006-05-30

    The Community Atmosphere Model (CAM) is the atmospheric component of the Community Climate System Model (CCSM) and is the primary consumer of computer resources in typical CCSM simulations. Performance engineering has been an important aspect of CAM development throughout its existence. This paper briefly summarizes these efforts and their impacts over the past five years.

  4. EXAMPLE APPLICATION OF CFD SIMULATIONS FOR SHORT-RANGE ATMOSPHERIC DISPERSION OVER THE OPEN FIELDS OF PROJECT PRAIRIE GRASS

    Science.gov (United States)

    Computational Fluid Dynamics (CFD) techniques are increasingly being applied to air quality modeling of short-range dispersion, especially the flow and dispersion around buildings and other geometrically complex structures. The proper application and accuracy of such CFD techniqu...

  5. NARAC Dispersion Model Product Integration With RadResponder

    Energy Technology Data Exchange (ETDEWEB)

    Aluzzi, Fernando [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-09-30

    Work on enhanced cooperation and interoperability of Nuclear Incident Response Teams (NIRT) is a joint effort between DHS/FEMA, DOE/NNSA and EPA. One such effort was the integration between the RadResponder Network, a resource sponsored by FEMA for the management of radiological data during an emergency, and the National Atmospheric Advisory Center (NARAC), a DOE/NNSA modeling resource whose predictions are used to aid radiological emergency preparedness and response. Working together under a FEMA-sponsored project these two radiological response assets developed a capability to read and display plume model prediction results from the NARAC computer system in the RadResponder software tool. As a result of this effort, RadResponder users have been provided with NARAC modeling predictions of contamination areas, radiological dose levels, and protective action areas (e.g., areas warranting worker protection or sheltering/evacuation) to help guide protective action decisions and field monitoring surveys, and gain key situation awareness following a radiological/nuclear accident or incident (e.g., nuclear power plant accident, radiological dispersal device incident, or improvised nuclear detonation incident). This document describes the details of this integration effort.

  6. Dispersion of aerosol particles in the free atmosphere using ensemble forecasts

    Directory of Open Access Journals (Sweden)

    T. Haszpra

    2013-10-01

    Full Text Available The dispersion of aerosol particle pollutants is studied using 50 members of an ensemble forecast in the example of a hypothetical free atmospheric emission above Fukushima over a period of 2.5 days. Considerable differences are found among the dispersion predictions of the different ensemble members, as well as between the ensemble mean and the deterministic result at the end of the observation period. The variance is found to decrease with the particle size. The geographical area where a threshold concentration is exceeded in at least one ensemble member expands to a 5–10 times larger region than the area from the deterministic forecast, both for air column "concentration" and in the "deposition" field. We demonstrate that the root-mean-square distance of any particle from its own clones in the ensemble members can reach values on the order of one thousand kilometers. Even the centers of mass of the particle cloud of the ensemble members deviate considerably from that obtained by the deterministic forecast. All these indicate that an investigation of the dispersion of aerosol particles in the spirit of ensemble forecast contains useful hints for the improvement of risk assessment.

  7. Modelling surface radioactive spill dispersion in the Alboran Sea

    Energy Technology Data Exchange (ETDEWEB)

    Perianez, R. [Dpto. Fisica Aplicada I, E.U. Ingenieria Tecnica Agricola, Universidad de Sevilla. Ctra. Utrera km 1, 41013 Sevilla (Spain)]. E-mail: rperianez@us.es

    2006-07-01

    The Strait of Gibraltar and the Alboran Sea are the only connection between the Atlantic Ocean and the Mediterranean Sea. Intense shipping activities occur in the area, including transport of waste radionuclides and transit of nuclear submarines. Thus, it is relevant to have a dispersion model that can be used in an emergency situation after an accident, to help the decision-making process. Such dispersion model requires an appropriate description of the physical oceanography of the region of interest, with simulations of tides and residual (average) circulation. In this work, a particle-tracking dispersion model that can be used to simulate the dispersion of radionuclides in the system Strait of Gibraltar-Alboran Sea is described. Tides are simulated using a barotropic model and for the average circulation a reduced-gravity model is applied. This model is able to reproduce the main features of the Alboran circulation (the well known Western Alboran Gyre, WAG, and the coastal circulation mode). The dispersion model is run off-line, using previously computed tidal and residual currents. The contamination patch is simulated by a number of particles whose individual paths are computed; diffusion and decay being modelled using a Monte Carlo method. Radionuclide concentrations may be obtained from the density of particles per water volume unit. Results from the hydrodynamic models have been compared with observations in the area. Several examples of dispersion computations under different wind and circulation conditions are presented.

  8. Modelling long-distance seed dispersal in heterogeneous landscapes.

    Energy Technology Data Exchange (ETDEWEB)

    Levey, Douglas, J.; Tewlsbury, Joshua, J.; Bolker, Benjamin, M.

    2008-01-01

    1. Long-distance seed dispersal is difficult to measure, yet key to understanding plant population dynamics and community composition. 2. We used a spatially explicit model to predict the distribution of seeds dispersed long distances by birds into habitat patches of different shapes. All patches were the same type of habitat and size, but varied in shape. They occurred in eight experimental landscapes, each with five patches of four different shapes, 150 m apart in a matrix of mature forest. The model was parameterized with smallscale movement data collected from field observations of birds. In a previous study we validated the model by testing its predictions against observed patterns of seed dispersal in real landscapes with the same types and spatial configuration of patches as in the model. 3. Here we apply the model more broadly, examining how patch shape influences the probability of seed deposition by birds into patches, how dispersal kernels (distributions of dispersal distances) vary with patch shape and starting location, and how movement of seeds between patches is affected by patch shape. 4. The model predicts that patches with corridors or other narrow extensions receive higher numbers of seeds than patches without corridors or extensions. This pattern is explained by edgefollowing behaviour of birds. Dispersal distances are generally shorter in heterogeneous landscapes (containing patchy habitat) than in homogeneous landscapes, suggesting that patches divert the movement of seed dispersers, ‘holding’ them long enough to increase the probability of seed defecation in the patches. Dispersal kernels for seeds in homogeneous landscapes were smooth, whereas those in heterogenous landscapes were irregular. In both cases, long-distance (> 150 m) dispersal was surprisingly common, usually comprising approximately 50% of all dispersal events. 5. Synthesis . Landscape heterogeneity has a large influence on patterns of long-distance seed dispersal. Our

  9. Modelling the observed vertical transport of {sup 7}Be in specific soils with advection dispersion model

    Energy Technology Data Exchange (ETDEWEB)

    Torres Astorga, Romina; Velasco, Hugo; Valladares, Diego L.; Lohaiza, Flavia; Ayub, Jimena Juri; Rizzotto, Marcos [Grupo de Estudios Ambientales. Instituto de Matematica Aplicada San Luis - Universidad Nacional de San Luis - CONICET, San Luis (Argentina)

    2014-07-01

    {sup 7}Be is a short-lived environmental radionuclide, produced in the upper atmosphere by spallation of nitrogen and oxygen by cosmic rays. After of the production by the nuclear reaction, {sup 7}Be diffuses through the atmosphere until it attaches to atmospheric aerosols. Subsequently, it is deposited on the earth surface mainly as wet fallout. The main physical processes which transport {sup 7}Be in soil are diffusion and advection by water. Migration parameters and measurements confirm that sorption is the main physical process, which confines {sup 7}Be concentration to soil surface. The literature data show that in soils, {sup 7}Be is concentrated near the surface (0-2 cm) as it is adsorbed onto clay minerals after its deposition on the soil surface and does not penetrate deeper into soils due to its short half-life. The maximum mass activity density of {sup 7}Be is found at the point of input of the radionuclide, i.e. at the surface of the soil column, showing a exponential distribution profile typical of a purely diffusive transport. Many studies applying the advection dispersion models have been reported in the literature in order to modelling the transport of {sup 137}Cs in soils. On them, the models are used to achieve information of the mechanisms that govern the transport, i. e. the model is used to explain the soil profile of radionuclide. The effective dispersion coefficient and the apparent advection velocity of radionuclide in soil are also obtained by fitting the analytical solution of the model equation to measured depth distributions of the radionuclide. In this work, the advective dispersive transport model with linear sorption is used to analyze the vertical migration process of {sup 7}Be in soils of undisturbed or reference sites. The deposition history is approximated by pulse-like input functions and time dependent analytical solution of equation model is obtained. The values of dispersion coefficient and apparent advection velocity obtained

  10. RETADDII: modeling long-range atmospheric transport of radionuclides

    International Nuclear Information System (INIS)

    A versatile model is described which estimates atmospheric dispersion based on plume trajectories calculated for the mixed layer. This model allows the treatment of the dispersal from a source at an arbitrary height while taking account of plume depletion by dry and wet deposition together with the decay of material to successor species. The plume depletion, decay and growth equations are solved in an efficient manner which can accommodate up to eight pollutants (i.e. a parent and seven serial decay products). The code is particularly suitable for applications involving radioactive chain decay or for cases involving chemical species with successor decay products. Arbitrary emission rates can be specified for the members of the chain or, as is commonly the case, a sole emission rate can be specified for the first member. The code, in its current configuration, uses readily available upper-air wind data for the North American continent

  11. Source term for atmospheric dispersion in pipeline rupture; Termo fonte para dispersao atmosferica em ruptura de gasoduto

    Energy Technology Data Exchange (ETDEWEB)

    Reis, Rubem da Cunha [Pontificia Univ. Catolica do Rio Grande do Sul, Porto Alegre, RS (Brazil). Faculdade de Engenharia. Dept. de Engenharia Quimica]. E-mail: rreis@eq.pucrs.br; Leal, Cesar Antonio [Universidade Federal do Rio Grande do Sul, Porto Alegre, RS (Brazil). Dept. de Engenharia Nuclear. Programa de Pos-graduacao em Engenharia Mecanica]. E-mail: leal@vortex.ufrgs.br

    2003-07-01

    The evaluation of consequences of industrial accidents requires the determination of physical effects in the several stages that compose a sequence of events that needs to be modeled. When a dangerous product is liberated accidentally, in order to the estimate of the possible number of victims in the scenario under consideration, one needs to evaluate the amount of released material, its physical state, and the amount that becomes airborne to form the source term for dispersion. Natural gas, transported in pipelines, is already crossing the state of Rio Grande do Sul, where, as well as in another areas of the country, it will be widely used. The need to overcome large distances between distribution and consuming units of natural gas implies in the use of high pressure conditions for transportation. The modeling of the behavior of the system in case of an accidents under this condition of quite severe pressure was done in a similar fashion used in a previous work where good results were obtained. The pipeline initial conditions are supercritical. In this paper, it is presented a discussion and results of the amount of natural gas that would be liberated in the form gas for further dispersion in the atmosphere, for the case of a pipeline initially in the pressure of 7 MPa and ambient temperature. (author)

  12. Dispersive processes in models of regional radionuclide migration. Technical memorandum

    International Nuclear Information System (INIS)

    Three broad areas of concern in the development of aquifer scale transport models will be local scale diffusion and dispersion processes, regional scale dispersion processes, and numerical problems associated with the advection-dispersion equation. Local scale dispersion processes are fairly well understood and accessible to observation. These processes will generally be dominated in large scale systems by regional processes, or macro-dispersion. Macro-dispersion is primarily the result of large scale heterogeneities in aquifer properties. In addition, the effects of many modeling approximations are often included in the process. Because difficulties arise in parameterization of this large scale phenomenon, parameterization should be based on field measurements made at the same scale as the transport process of interest or else partially circumvented through the application of a probabilistic advection model. Other problems associated with numerical transport models include difficulties with conservation of mass, stability, numerical dissipation, overshoot, flexibility, and efficiency. We recommend the random-walk model formulation for Lawrence Livermore Laboratory's purposes as the most flexible, accurate and relatively efficient modeling approach that overcomes these difficulties

  13. Aquatic dispersion modelling of a tritium plume in Lake Ontario

    International Nuclear Information System (INIS)

    Approximately 2900 kg of tritiated water, containing 2.3E+15 Bq of tritium, were released to Lake Ontario via the cooling water discharge when a leak developed in a moderator heat exchanger in Unit 1 at the Pickering Nuclear Generating Station (PNGS) on 1992 August 2. The release provided the opportunity to study the dispersion of a tritium plume in the coastal zone of Lake Ontario. Current direction over the two-week period following the release was predominantly parallel to the shore, and elevated tritium concentrations were observed up to 20 km east and 85 km west of the PNGS. Predictions of the tritium plume movement were made using current velocity measurements taken at 8-m depth, 2.5 km offshore from Darlington and using a empirical relationship where alongshore current speed is assumed to be proportional to the alongshore component of the wind speed. The tritium migration was best described using current velocity measurements. The tritium plume dispersion is modelled using the one-dimensional advection-dispersion equation. Transport parameters are the alongshore current speed and longitudinal dispersion coefficient. Longitudinal dispersion coefficients, estimated by fitting the solution of the advection-dispersion equation to measured concentration distance profiles ranged from 3.75 to 10.57 m2s-1. Simulations using the fitted values of the dispersion coefficient were able to describe maximum tritium concentrations measured at water supply plants located within 25 km of Pickering to within a factor of 3. The dispersion coefficient is a function of spatial and temporal variability in current velocity and the fitted dispersion coefficients estimated here may not be suitable for predicting tritium plume dispersion under different current conditions. The sensitivity of the dispersion coefficient to variability in current conditions should be evaluated in further field experiments. (author). 13 refs., 7 tabs., 12 figs

  14. Soil-vegetation-atmosphere transfer modeling

    Energy Technology Data Exchange (ETDEWEB)

    Ikonen, J.P.; Sucksdorff, Y. [Finnish Environment Agency, Helsinki (Finland)

    1996-12-31

    In this study the soil/vegetation/atmosphere-model based on the formulation of Deardorff was refined to hour basis and applied to a field in Vihti. The effect of model parameters on model results (energy fluxes, temperatures) was also studied as well as the effect of atmospheric conditions. The estimation of atmospheric conditions on the soil-vegetation system as well as an estimation of the effect of vegetation parameters on the atmospheric climate was estimated. Areal surface fluxes, temperatures and moistures were also modelled for some river basins in southern Finland. Land-use and soil parameterisation was developed to include properties and yearly variation of all vegetation and soil types. One classification was selected to describe the hydrothermal properties of the soils. Evapotranspiration was verified against the water balance method

  15. Comparative analysis of three atmospheric dispersion coefficient systems at the Angra dos Reis, RJ, region

    International Nuclear Information System (INIS)

    A comparative analysis was made in this work among Pasquill-Gifford (PG) atmospheric dispersion coefficients and those determined at the Juelich and Karlsruhe sites with the purpose of suggesting which one would be the most applicable to the Angra site. Each one of the three systems was determined by different experiments, carried out over sites with diversified features. The systems of Juelich and Karlsruhe were obtained over sites with high surface roughness and from stacks (elevated releases), while the PG system was obtained over sites with a small surface roughness and from ground level releases. The results of the application of these systems at a complex site like Angra,which has a highly diversified structure encompassing sea, vegetation, predominance of light winds and stable stability classes, show that the PG system, the most used in the world, is still the best choice. (author)

  16. Modelling the atmospheric chemistry of volcanic plumes

    OpenAIRE

    Surl, Luke

    2016-01-01

    Abstract Volcanoes are the principal way by which volatiles are transferred from the solid Earth to the atmosphere-hydrosphere system. Once released into the atmosphere, volcanic emissions rapidly undergo a complex series of chemical reactions. This thesis seeks to further the understanding of such processes by both observation and numerical modelling. I have adapted WRF-Chem to model passive degassing from Mount Etna, the chemistry of its plume, and its influence on the ...

  17. An online educational atmospheric global circulation model

    Science.gov (United States)

    Navarro, T.; Schott, C.; Forget, F.

    2015-10-01

    As part of online courses on exoplanets of Observatoire de Paris, an online tool designed to vizualise outputs of the Laboratoire de Métérologie Dynamique (LMD) Global Circulation Model (GCM) for various atmospheric circulation regimes has been developed. It includes the possibility for students to visualize 1D and 2D plots along with animations of atmospheric quantities such as temperature, winds, surface pressure, mass flux, etc... from a state-of-the-art model.

  18. Biomonitoring of airborne particulate matter emitted from a cement plant and comparison with dispersion modelling results

    Science.gov (United States)

    Abril, Gabriela A.; Wannaz, Eduardo D.; Mateos, Ana C.; Pignata, María L.

    2014-01-01

    The influence of a cement plant that incinerates industrial waste on the air quality of a region in the province of Córdoba, Argentina, was assessed by means of biomonitoring studies (effects of immission) and atmospheric dispersion (effects of emission) of PM10 with the application of the ISC3 model (Industrial Source Complex) developed by the USEPA (Environmental Protection Agency). For the biomonitoring studies, samples from the epiphyte plant Tillandsia capillaris Ruíz & Pav. f. capillaris were transplanted to the vicinities of the cement plant in order to determine the physiological damage and heavy metal accumulation (Ca, Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb). For the application of the ISC3 model, point and area sources from the cement plant were considered to obtain average PM10 concentration results from the biomonitoring exposure period. This model permitted it to be determined that the emissions from the cement plant (point and area sources) were confined to the vicinities, without significant dispersion in the study area. This was also observed in the biomonitoring study, which identified Ca, Cd and Pb, pH and electric conductivity (EC) as biomarkers of this cement plant. Vehicular traffic emissions and soil re-suspension could be observed in the biomonitors, giving a more complete scenario. In this study, biomonitoring studies along with the application of atmospheric dispersion models, allowed the atmospheric pollution to be assessed in more detail.

  19. CFD Modeling of Particulate Matter Dispersion from Kerman Cement Plant

    Directory of Open Access Journals (Sweden)

    M. Panahandeh

    2010-04-01

    Full Text Available "n "n "nBackgrounds and Objectives: The dispersion of particulate matter has been known as the most serious environmental pollution of cement plants. In the present work, dispersion of the particulate matter from stack of Kerman Cement Plant was investigated using Computational Fluid Dynamics (CFD modeling."nMaterials and Methods: In order to study the dispersion of particulate matter from the stack, a calculation domain with dimensions of 8000m × 800m × 400m was considered. The domain was divided to 936781 tetrahedral control volumes. The mixture two-phase model was employed to model the interaction of the particulate matter (dispersed phase and air (continuous phase. The Large Eddy Simulation (LES method was used for turbulence modeling."nResults: The concentration of particulate matter in the whole calculation domain was computed. The predicted concentrations were compared to the measured values from the literature and a good agreement was observed. The predicted concentration profiles at different cross sections were analyzed."nConclusion:The results of the present work showed that CFD is a useful tool for understanding the dispersion of particulate matter in air. Although the obtained results were promising, more investigations on the properties of the dispersed phase, turbulent parameters and the boundary layer effect is needed to obtain more accurate results.

  20. Sensitivity of wave-length dispersive x-ray fluorescence of atmospheric aerosols

    International Nuclear Information System (INIS)

    The possibilities of wave-length dispersive x-ray spectrometry for the elemental analysis of the inorganic fraction of atmospheric aerosols collected on filter materials were thoroughly investigated. Three filter-types, namely one cellulose filter (Whatman 41) and two membrane filters (Millipore AAWP, pore size 0.8 um and Nuclepore, pore size 0.4 um) were compared. In order to measure the Nuclepore filters in a reproducible geometry under vacuum condition, a number of minor technical modifications had to be applied to the Philips PW 1450 spectrometer. X-ray tubes with chromium, tungsten, or silver anticathodes were tested for their capabilities for excitation of the particulate material. To obtain a wide range of elements, whether by their K-x rays or by their L-x rays, the tungsten tube appeared to be the best compromise. Detection limits of typical atmospheric aerosols after a 24 hour sampling on Nuclepore filters with a dust load of less than 100 ug. cm-2, were derived for Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Sr (K-x rays), Cd, Sn, Sb, Ba and Pb

  1. Modeling for pollution dispersion and air quality 4.: the Gaussian model

    International Nuclear Information System (INIS)

    The Gaussian Model is the simulation model for atmospheric pollutant dispersion most used in practice, in particular for engineering applications; it has been the first model used in the United States to predict the impact of pollutant sources on air quality and for many years it has constituted the projecting instrument in environmental and territory planning; today it is still a very useful instrument, above all when the meteorological input data are not so abundant. In recent year, great efforts have been made to extend the original Gaussian model to different typologies of sources and to make it able to treat more detailed effects, as, for example, a complex terrain, the dry deposition, the gravity effect on heavy particulate matter and other microscale effects. In this work, the main characteristics of the Gaussian model and the equations which govern its description of the dispersion of air pollutants are discussed; moreover, the main used codices which implement Gaussian models which can be easily found in commerce or, sometimes, in the net, are briefly described

  2. Regional forecasting with global atmospheric models

    International Nuclear Information System (INIS)

    The scope of the report is to present the results of the fourth year's work on the atmospheric modeling part of the global climate studies task. The development testing of computer models and initial results are discussed. The appendices contain studies that provide supporting information and guidance to the modeling work and further details on computer model development. Complete documentation of the models, including user information, will be prepared under separate reports and manuals

  3. High-accuracy alignment based on atmospherical dispersion - technological approaches and solutions for the dual-wavelength transmitter

    Energy Technology Data Exchange (ETDEWEB)

    Burkhard, Boeckem [Institute for Geodesy and Photogrammetry, ETH Zurich (Switzerland)

    1999-07-01

    In the course of the progressive developments of sophisticated geodetic systems utilizing electromagnetic waves in the visible or near IR-range a more detailed knowledge of the propagation medium and coevally solutions of atmospherically induced limitations will become important. An alignment system based on atmospherical dispersion, called a dispersometer, is a metrological solution to the atmospherically induced limitations, in optical alignment and direction observations of high accuracy. In the dispersometer we are using the dual-wavelength method for dispersive air to obtain refraction compensated angle measurements, the detrimental impact of atmospheric turbulence notwithstanding. The principle of the dual-wavelength method utilizes atmospherical dispersion, i.e. the wavelength dependence of the refractive index. The difference angle between two light beams of different wavelengths, which is called the dispersion angle {delta}{beta}, is to first approximation proportional to the refraction angle: {beta}{sub IR} {nu}({beta}{sub blue} - {beta}{sub IR}) = {nu} {delta}{beta}, this equation implies that the dispersion angle has to be measured at least 42 times more accurate than the desired accuracy of the refraction angle for the wavelengths used in the present dispersometer. This required accuracy constitutes one major difficulty for the instrumental performance in applying the dispersion effect. However, the dual-wavelength method can only be successfully used in an optimized transmitter-receiver combination. Beyond the above mentioned resolution requirement for the detector, major difficulties in instrumental realization arise in the availability of a suitable dual-wavelength laser light source, laser light modulation with a very high extinction ratio and coaxial emittance of mono-mode radiation at both wavelengths. Therefore, this paper focuses on the solutions of the dual-wavelength transmitter introducing a new hardware approach and a complete re-design of

  4. Atmospheric radionuclide transport model with radon postprocessor and SBG module. Model description version 2.8.0

    International Nuclear Information System (INIS)

    The study on the atmospheric radionuclide transport model with radon postprocessor and SBG module (model description version 2.8.0) covers the following issues: determination of emissions, radioactive decay, atmospheric dispersion calculation for radioactive gases, atmospheric dispersion calculation for radioactive dusts, determination of the gamma cloud radiation (gamma submersion), terrain roughness, effective source height, calculation area and model points, geographic reference systems and coordinate transformations, meteorological data, use of invalid meteorological data sets, consideration of statistical uncertainties, consideration of housings, consideration of bumpiness, consideration of terrain roughness, use of frequency distributions of the hourly dispersion situation, consideration of the vegetation period (summer), the radon post processor radon.exe, the SBG module, modeling of wind fields, shading settings.

  5. Users of middle atmosphere models remarks

    Science.gov (United States)

    Gamble, Joe

    1987-01-01

    The procedure followed for shuttle operations is to calculate descent trajectories for each potential shuttle landing site using the Global Reference Atmosphere Model (GRAM) to interactively compute density along the flight path 100 times to bound the statistics. The purpose is to analyze the flight dynamics, along with calculations of heat loads during reentry. The analysis program makes use of the modified version of the Jacchia-70 atmosphere, which includes He bulges over the poles and seasonal latitude variations at lower altitudes. For the troposphere, the 4-D Model is used up to 20 km, Groves from 30 km up to 90 km. It is extrapolated over the globe and faired into the Jacchia atmosphere between 90 and 115 km. Since data on the Southern Hemisphere was lacking, what was done was that the data was flipped over and lagged 6 months. Sometimes when winds are calculated from pressure data in the model there appear to be discontinuities. Modelers indicated that the GRAM was not designed to produce winds, but good wind data is needed for the landing phase of shuttle operations. Use of atmospheric models during reentry is one application where it is obvious that a single integrated atmosphere model is required.

  6. Atmospheric distribution of methane on Mars: A model study

    Science.gov (United States)

    Viscardy, Sébastien; Daerden, Frank; Neary, Lori

    2016-10-01

    In the past decade, the detection of methane (CH4) in the atmosphere of Mars has been reported several times. These observations have strongly drawn the attention of the scientific community and triggered a renewed interest in Mars as their implications for the geochemical or biological activities are remarkable. However, given that methane is expected to have a photochemical lifetime of several centuries, the relatively fast loss rates of methane estimated from Earth-based measurements remain unexplained. Although this gave rise to objections against the validity of those observations, recent in situ measurements confirmed that methane is being occasionally released into the atmosphere from an unknown source (possibly from the ground). Additionally, ExoMars/TGO was launched to Mars in March 2016. NOMAD, one of the instruments onboard TGO, will provide the first global detailed observations of methane on Mars. It is in this context that we present a model study of the behavior of methane plumes.A general circulation model for the atmosphere of Mars is applied to simulate surface emission of methane and to investigate its vertical distribution during the first weeks after the release. Such surface emissions were suggested to explain observations of methane. Previous GCM simulations focused on the horizontal evolution of the methane, but the present study focuses on the three-dimensional dispersion of methane throughout the atmosphere after the surface release. It is found that a highly nonuniform vertical distribution, including distinct vertical layers, can appear throughout the atmosphere during the first weeks after the emission. This is explained by the global circulation patterns in the atmosphere at the time of the emission. Large Hadley cells transport the methane rapidly to other locations over the planet, and methane will be stretched out in layers along the general circulation streamlines at heights corresponding to strong zonal jets.This result changes

  7. SIRANERISK: Modelling dispersion of steady and unsteady pollutant releases in the urban canopy

    Science.gov (United States)

    Soulhac, L.; Lamaison, G.; Cierco, F.-X.; Ben Salem, N.; Salizzoni, P.; Mejean, P.; Armand, P.; Patryl, L.

    2016-09-01

    SIRANERISK is an operational model for the simulation of the dispersion of unsteady atmospheric releases of pollutant within and above an urban area. SIRANERISK is built on the same principles as the SIRANE model, and couples a street network model for the pollutant transfers within the urban canopy with a Gaussian puff model for the transfers above it. The performance of the model are here analysed by a detailed comparisons with wind-tunnel experiments. These experiments concern the dispersion of steady and unsteady pollutant releases within and above obstacle arrays with varying geometrical configurations, representing different topologies of idealised urban districts. The overall good agreement between numerical and experimental data demonstrates the reliability of SIRANERISK as an operational tool for the assessment of risk analysis and for the management of crises due to the accidental release of harmful airborne pollutants within a built environment.

  8. A model for long-distance dispersal of boll weevils (Coleoptera: Curculionidae)

    Science.gov (United States)

    Westbrook, John K.; Eyster, Ritchie S.; Allen, Charles T.

    2011-07-01

    The boll weevil, Anthonomus grandis (Boheman), has been a major insect pest of cotton production in the US, accounting for yield losses and control costs on the order of several billion US dollars since the introduction of the pest in 1892. Boll weevil eradication programs have eliminated reproducing populations in nearly 94%, and progressed toward eradication within the remaining 6%, of cotton production areas. However, the ability of weevils to disperse and reinfest eradicated zones threatens to undermine the previous investment toward eradication of this pest. In this study, the HYSPLIT atmospheric dispersion model was used to simulate daily wind-aided dispersal of weevils from the Lower Rio Grande Valley (LRGV) of southern Texas and northeastern Mexico. Simulated weevil dispersal was compared with weekly capture of weevils in pheromone traps along highway trap lines between the LRGV and the South Texas / Winter Garden zone of the Texas Boll Weevil Eradication Program. A logistic regression model was fit to the probability of capturing at least one weevil in individual pheromone traps relative to specific values of simulated weevil dispersal, which resulted in 60.4% concordance, 21.3% discordance, and 18.3% ties in estimating captures and non-captures. During the first full year of active eradication with widespread insecticide applications in 2006, the dispersal model accurately estimated 71.8%, erroneously estimated 12.5%, and tied 15.7% of capture and non-capture events. Model simulations provide a temporal risk assessment over large areas of weevil reinfestation resulting from dispersal by prevailing winds. Eradication program managers can use the model risk assessment information to effectively schedule and target enhanced trapping, crop scouting, and insecticide applications.

  9. Stellar model atmospheres with magnetic line blanketing

    CERN Document Server

    Kochukhov, O; Shulyak, D

    2004-01-01

    Model atmospheres of A and B stars are computed taking into account magnetic line blanketing. These calculations are based on the new stellar model atmosphere code LLModels which implements direct treatment of the opacities due to the bound-bound transitions and ensures an accurate and detailed description of the line absorption. The anomalous Zeeman effect was calculated for the field strengths between 1 and 40 kG and a field vector perpendicular to the line of sight. The model structure, high-resolution energy distribution, photometric colors, metallic line spectra and the hydrogen Balmer line profiles are computed for magnetic stars with different metallicities and are discussed with respect to those of non-magnetic reference models. The magnetically enhanced line blanketing changes the atmospheric structure and leads to a redistribution of energy in the stellar spectrum. The most noticeable feature in the optical region is the appearance of the 5200 A depression. However, this effect is prominent only in ...

  10. ARAC dispersion modeling of the July 26, 1993 oleum tank car spill in Richmond, California

    Energy Technology Data Exchange (ETDEWEB)

    Baskett, R.L.; Vogt, P.J.; Schalk, W.W. III; Pobanz, B.M. [EG and G Energy Measurements, Inc., Pleasanton, CA (United States)

    1994-02-03

    This report presents the results from the real-time response on the day of the spill followed by a re-assessment of the spill. Worst-case source terms and readily available meteorological data (met data) were used for the real-time response. ARAC employs a three-dimensional, diagnostic, finite-difference dispersion modeling system for estimating the consequences from accidental atmospheric releases. MATHEW (Mass-Adjusted Three- Dimensional Wind field), a Eulerian wind field code, and ADPIC (Atmospheric Diffusion by Particle-In-Cell), a hybrid Eulerian-Lagrangian dispersion model, from the core of the system. For a particular incident a model grid is selected to encompass the area of concern and is generated using underlying terrain from on-line data. Meteorological data from multiple surface and upper air stations are automatically acquired in real time primarily from local airports and formatted to initialize the wind field model. Dispersion parameters are determined from meteorological data and the source term from available information. The system is designed to simulate releases from single or multiple radioactive releases, such as ventings, spills, fires, or explosions. Solid and liquid aerosols and neutrally-buoyant gases are modeled. Particle size distributions are input for each aerosol source and modeled using gravitational settling and wet and dry deposition, if applicable. The system can be readily applied to neutrally-bouyant, nonradioactive chemical releases which do not undergo significant physical or chemical conversion processes.

  11. New atmospheric model of Epsilon Eridani

    Science.gov (United States)

    Vieytes, Mariela; Fontenla, Juan; Buccino, Andrea; Mauas, Pablo

    2016-05-01

    We present a new semi-empirical model of the atmosphere of the widely studied K-dwarf Epsilon Eridani (HD 22049). The model is build to reproduce the visible spectral observations from 3800 to 6800 Angstrom and the h and k Mg II lines profiles. The computations were carried out using the Solar-Stellar Radiation Physical Modeling (SSRPM) tools, which calculate non-LTE population for the most important species in the stellar atmosphere. We show a comparison between the synthetic and observed spectrum, obtaining a good agreement in all the studied spectral range.

  12. Comparison between the Chinese EIA Guidelines for Air Dispersion Modelling and the Advanced Air Dispersion Model ADMS

    Institute of Scientific and Technical Information of China (English)

    David Carruthers; Sheng Xiangyu; Christine McHugh

    2005-01-01

    This paper makes comparisons between Chinese Environmental Impact Assessment (EIA)Guidelines for Air dispersion modelling and the advanced air dispersion model ADMS. Since 2001 the ADMS model has been the first and only foreign model that has been approved by the Appraisal Center for Environment and Engineering (ACEE) to be used in EIA projects in China (http://www. china-eia.com/inden_content/rjrz/rjrz_ADMS/htm). In the paper the following sections provide brief descriptions of the main features of the Chinese Guidelines for Air Dispersion (Section 2) and ADMS (Section 3);Section 4 provides a comparison of the two modelling methods for some simple cases and conclusions and discussion are given in Section 5.

  13. Statistics of Absolute and Relative Dispersion in the Atmospheric Convective Boundary Layer: A Large-Eddy Simulation Study

    NARCIS (Netherlands)

    Dosio, A.; Vilà-Guerau de Arellano, J.

    2006-01-01

    The influence of the different scales of turbulent motion on plume dispersion in the atmospheric convective boundary layer (CBL) is studied by means of a large-eddy simulation (LES). In particular, the large-scale (meandering) and small-scale (relative diffusion) contributions are separated by analy

  14. Comparison of CFD and operational dispersion models in an urban-like environment

    Science.gov (United States)

    Antonioni, G.; Burkhart, S.; Burman, J.; Dejoan, A.; Fusco, A.; Gaasbeek, R.; Gjesdal, T.; Jäppinen, A.; Riikonen, K.; Morra, P.; Parmhed, O.; Santiago, J. L.

    2012-02-01

    Chemical plants, refineries, transportation of hazardous materials are some of the most attractive facilities for external attacks aimed at the release of toxic substances. Dispersion of these substances into the atmosphere forms a concentration distribution of airborne pollutants with severe consequences for exposed individuals. For emergency preparedness and management, the availability of assessed/validated dispersion models, which can be able to predict concentration distribution and thus dangerous zones for exposed individuals, is of primary importance. Air quality models, integral models and analytical models predict the transport and the turbulent dispersion of gases or aerosols after their release without taking into account in detail the presence of obstacles. Obstacles can modify the velocity field and in turn the concentration field. The Computational Fluid Dynamics (CFD) models on the other hand are able to describe such phenomena, but they need to be correctly set up, tested and validated in order to obtain reliable results. Within the project Europa-ERG1 TA 113.034 "NBC Modelling and Simulation" several different approaches in CFD modelling of turbulent dispersion in closed, semi-confined and urban-like environment were adopted and compared with experimental data and with operational models. In this paper the results of a comparison between models describing the dispersion of a neutral gas in an idealized urban-like environment are presented and discussed. Experimental data available in the literature have been used as a benchmark for assessing statistical performance for each model. Selected experimental trials include some water channel tests, that were performed by Coanda at 1:205 scale, and one full-scale case that was tested in the fall of 2001 at the Dugway Proving Grounds in Utah, using an array of shipping containers. The paper also suggests the adoption of improved statistical parameters in order to better address differences between models

  15. Computer Models Simulate Fine Particle Dispersion

    Science.gov (United States)

    2010-01-01

    Through a NASA Seed Fund partnership with DEM Solutions Inc., of Lebanon, New Hampshire, scientists at Kennedy Space Center refined existing software to study the electrostatic phenomena of granular and bulk materials as they apply to planetary surfaces. The software, EDEM, allows users to import particles and obtain accurate representations of their shapes for modeling purposes, such as simulating bulk solids behavior, and was enhanced to be able to more accurately model fine, abrasive, cohesive particles. These new EDEM capabilities can be applied in many industries unrelated to space exploration and have been adopted by several prominent U.S. companies, including John Deere, Pfizer, and Procter & Gamble.

  16. Xenon-133 and caesium-137 releases into the atmosphere from the Fukushima Dai-ichi nuclear power plant: determination of the source term, atmospheric dispersion, and deposition

    Directory of Open Access Journals (Sweden)

    A. Stohl

    2011-10-01

    Full Text Available On 11 March 2011, an earthquake occurred about 130 km off the Pacific coast of Japan's main island Honshu, followed by a large tsunami. The resulting loss of electric power at the Fukushima Dai-ichi nuclear power plant (FD-NPP developed into a disaster causing massive release of radioactivity into the atmosphere. In this study, we determine the emissions of two isotopes, the noble gas xenon-133 (133Xe and the aerosol-bound caesium-137 (137Cs, which have very different release characteristics as well as behavior in the atmosphere. To determine radionuclide emissions as a function of height and time until 20 April, we made a first guess of release rates based on fuel inventories and documented accident events at the site. This first guess was subsequently improved by inverse modeling, which combined the first guess with the results of an atmospheric transport model, FLEXPART, and measurement data from several dozen stations in Japan, North America and other regions. We used both atmospheric activity concentration measurements as well as, for 137Cs, measurements of bulk deposition. Regarding 133Xe, we find a total release of 16.7 (uncertainty range 13.4–20.0 EBq, which is the largest radioactive noble gas release in history not associated with nuclear bomb testing. There is strong evidence that the first strong 133Xe release started very early, possibly immediately after the earthquake and the emergency shutdown on 11 March at 06:00 UTC. The entire noble gas inventory of reactor units 1–3 was set free into the atmosphere between 11 and 15 March 2011. For 137Cs, the inversion results give a total emission of 35.8 (23.3–50.1 PBq, or about 42% of the estimated Chernobyl emission. Our results indicate that 137Cs emissions peaked on 14–15 March but were generally high from 12 until 19 March, when they suddenly dropped by orders of magnitude exactly when spraying of

  17. Mathematical modeling of disperse two-phase flows

    CERN Document Server

    Morel, Christophe

    2015-01-01

    This book develops the theoretical foundations of disperse two-phase flows, which are characterized by the existence of bubbles, droplets or solid particles finely dispersed in a carrier fluid, which can be a liquid or a gas. Chapters clarify many difficult subjects, including modeling of the interfacial area concentration. Basic knowledge of the subjects treated in this book is essential to practitioners of Computational Fluid Dynamics for two-phase flows in a variety of industrial and environmental settings. The author provides a complete derivation of the basic equations, followed by more advanced subjects like turbulence equations for the two phases (continuous and disperse) and multi-size particulate flow modeling. As well as theoretical material, readers will discover chapters concerned with closure relations and numerical issues. Many physical models are presented, covering key subjects including heat and mass transfers between phases, interfacial forces and fluid particles coalescence and breakup, a...

  18. Coupled atmosphere-wildland fire modelling

    Directory of Open Access Journals (Sweden)

    Jacques Henri Balbi

    2009-10-01

    Full Text Available Simulating the interaction between fire and atmosphere is critical to the estimation of the rate of spread of the fire. Wildfire’s convection (i.e., entire plume can modify the local meteorology throughout the atmospheric boundary layer and consequently affect the fire propagation speed and behaviour. In this study, we use for the first time the Méso-NH meso-scale numerical model coupled to the point functional ForeFire simplified physical front-tracking wildfire model to investigate the differences introduced by the atmospheric feedback in propagation speed and behaviour. Both numerical models have been developed as research tools for operational models and are currently used to forecast localized extreme events. These models have been selected because they can be run coupled and support decisions in wildfire management in France and Europe. The main originalities of this combination reside in the fact that Méso-NH is run in a Large Eddy Simulation (LES configuration and that the rate of spread model used in ForeFire provides a physical formulation to take into account the effect of wind and slope. Simulations of typical experimental configurations show that the numerical atmospheric model is able to reproduce plausible convective effects of the heat produced by the fire. Numerical results are comparable to estimated values for fire-induced winds and present behaviour similar to other existing numerical approaches.

  19. Sensitivity of dispersion model forecasts of volcanic ash clouds to the physical characteristics of the particles

    Science.gov (United States)

    Beckett, F. M.; Witham, C. S.; Hort, M. C.; Stevenson, J. A.; Bonadonna, C.; Millington, S. C.

    2015-11-01

    This study examines the sensitivity of atmospheric dispersion model forecasts of volcanic ash clouds to the physical characteristics assigned to the particles. We show that the particle size distribution (PSD) used to initialise a dispersion model has a significant impact on the forecast of the mass loading of the ash particles in the atmosphere. This is because the modeled fall velocity of the particles is sensitive to the particle diameter. Forecasts of the long-range transport of the ash cloud consider particles with diameters between 0.1 μm and 100 μm. The fall velocity of particles with diameter 100 μm is over 5 orders of magnitude greater than a particle with diameter 0.1 μm, and 30 μm particles fall 88% slower and travel up to 5× further than a 100 μm particle. Identifying the PSD of the ash cloud at the source, which is required to initialise a model, is difficult. Further, aggregation processes are currently not explicitly modeled in operational dispersion models due to the high computational costs associated with aggregation schemes. We show that using a modified total grain size distribution (TGSD) that effectively accounts for aggregation processes improves the modeled PSD of the ash cloud and deposits from the eruption of Eyjafjallajökull in 2010. Knowledge of the TGSD of an eruption is therefore critical for reducing uncertainty in quantitative forecasts of ash cloud dispersion. The density and shape assigned to the model particles have a lesser but still significant impact on the calculated fall velocity. Accounting for the density distribution and sphericity of ash from the eruption of Eyjafjallajökull in 2010, modeled particles can travel up to 84% further than particles with default particle characteristics that assume the particles are spherical and have a fixed density.

  20. Investigation Of Compressor Heat Dispersion Model

    OpenAIRE

    Shi, Da; Tao, Hong; Yang, Min

    2014-01-01

    This paper represents a method for calculate the heat dissipation capacity and discharge temperature for rotary compressors. The proposed heat dissipation model is used for calculating heat dissipating capacity of compressor in forced-convection/natural-convection and radiation heat transfer mode. The comparison between calculated result and experimental result for both constant speed compressors and variable speed compressors shows that the average heat dissipating capacity error is below 20...

  1. Nonsmooth feedback controls of nonlocal dispersal models

    Science.gov (United States)

    Malaguti, Luisa; Rubbioni, Paola

    2016-03-01

    The paper deals with a nonlocal diffusion equation which is a model for biological invasion and disease spread. A nonsmooth feedback control term is included and the existence of controlled dynamics is proved, satisfying different kinds of nonlocal condition. Jump discontinuities appear in the process. The existence of optimal control strategies is also shown, under suitably regular control functionals. The investigation makes use of techniques of multivalued analysis and is based on the degree theory for condensing operators in Hilbert spaces.

  2. Electrokinetic induced solute dispersion in porous media; pore network modeling

    Science.gov (United States)

    Li, Shuai; Schotting, Ruud; Raoof, Amir

    2013-04-01

    Electrokinetic flow plays an important role in remediation process, separation technique, and chromatography. The solute dispersion is a key parameter to determine transport efficiency. In this study, we present the electrokinetic effects on solute dispersion in porous media at the pore scale, using a pore network model. The analytical solution of the electrokinetic coupling coefficient was obtained to quantity the fluid flow velocity in a cylinder capillary. The effect of electrical double layer on the electrokinetic coupling coefficient was investigated by applying different ionic concentration. By averaging the velocity over cross section within a single pore, the average flux was obtained. Applying such single pore relationships, in the thin electrical double layer limit, to each and every pore within the pore network, potential distribution and the induced fluid flow was calculated for the whole domain. The resulting pore velocities were used to simulate solute transport within the pore network. By averaging the results, we obtained the breakthrough curve (BTC) of the average concentration at the outlet of the pore network. Optimizing the solution of continuum scale advection-dispersion equation to such a BTC, solute dispersion coefficient was estimated. We have compared the dispersion caused by electrokinetic flow and pure pressure driven flow under different Peclet number values. In addition, the effect of microstructure and topological properties of porous media on fluid flow and solute dispersion is presented, mainly based on different pore coordination numbers.

  3. Tagging Water Sources in Atmospheric Models

    Science.gov (United States)

    Bosilovich, M.

    2003-01-01

    Tagging of water sources in atmospheric models allows for quantitative diagnostics of how water is transported from its source region to its sink region. In this presentation, we review how this methodology is applied to global atmospheric models. We will present several applications of the methodology. In one example, the regional sources of water for the North American Monsoon system are evaluated by tagging the surface evaporation. In another example, the tagged water is used to quantify the global water cycling rate and residence time. We will also discuss the need for more research and the importance of these diagnostics in water cycle studies.

  4. Portable University Model of the Atmosphere (PUMA)

    Energy Technology Data Exchange (ETDEWEB)

    Fraedrich, K.; Kirk, E.; Lunkeit, F. [Hamburg Univ. (Germany). Meteorologisches Inst.

    1998-10-01

    The Portable University Model of the Atmosphere (PUMA) is based on the Reading multi-level spectral model SGCM (Simple Global Circulation Model) described by Hoskins and Simmons (1975) and James and Gray (1986). Originally developed as a numerical prediction model, it was changed to perform as a circulation model. For example, James and Gray (1986) studied the influence of surface friction on the circulation of a baroclinic atmosphere, James and James (1992), and James et al. (1994) investigated ultra-low-frequency variability, and Mole and James (1990) analyzed the baroclinic adjustment in the context of a zonally varying flow. Frisius et al. (1998) simulated an idealized storm track by embedding a dipole structure in a zonally symmetric forcing field and Lunkeit et al. (1998) investigated the sensitivity of GCM (General Circulation Model) scenarios by an adaption technique applicapable to SGCMs. (orig.)

  5. Dispersive models describing mosquitoes’ population dynamics

    Science.gov (United States)

    Yamashita, W. M. S.; Takahashi, L. T.; Chapiro, G.

    2016-08-01

    The global incidences of dengue and, more recently, zica virus have increased the interest in studying and understanding the mosquito population dynamics. Understanding this dynamics is important for public health in countries where climatic and environmental conditions are favorable for the propagation of these diseases. This work is based on the study of nonlinear mathematical models dealing with the life cycle of the dengue mosquito using partial differential equations. We investigate the existence of traveling wave solutions using semi-analytical method combining dynamical systems techniques and numerical integration. Obtained solutions are validated through numerical simulations using finite difference schemes.

  6. Coupling approaches used in atmospheric entry models

    Science.gov (United States)

    Gritsevich, M. I.

    2012-09-01

    While a planet orbits the Sun, it is subject to impact by smaller objects, ranging from tiny dust particles and space debris to much larger asteroids and comets. Such collisions have taken place frequently over geological time and played an important role in the evolution of planets and the development of life on the Earth. Though the search for near-Earth objects addresses one of the main points of the Asteroid and Comet Hazard, one should not underestimate the useful information to be gleaned from smaller atmospheric encounters, known as meteors or fireballs. Not only do these events help determine the linkages between meteorites and their parent bodies; due to their relative regularity they provide a good statistical basis for analysis. For successful cases with found meteorites, the detailed atmospheric path record is an excellent tool to test and improve existing entry models assuring the robustness of their implementation. There are many more important scientific questions meteoroids help us to answer, among them: Where do these objects come from, what are their origins, physical properties and chemical composition? What are the shapes and bulk densities of the space objects which fully ablate in an atmosphere and do not reach the planetary surface? Which values are directly measured and which are initially assumed as input to various models? How to couple both fragmentation and ablation effects in the model, taking real size distribution of fragments into account? How to specify and speed up the recovery of a recently fallen meteorites, not letting weathering to affect samples too much? How big is the pre-atmospheric projectile to terminal body ratio in terms of their mass/volume? Which exact parameters beside initial mass define this ratio? More generally, how entering object affects Earth's atmosphere and (if applicable) Earth's surface? How to predict these impact consequences based on atmospheric trajectory data? How to describe atmospheric entry

  7. Description of the RIVM/KNMI PUFF dispersion model

    OpenAIRE

    Verver GHL; de Leeuw FAAM; van Rheineck Leyssius HJ

    1990-01-01

    In this report an atmospheric transport model (the RIVM/KNMI PUFF- model) is described. The model is intended for operational use at KNMI and RIVM in case of an accidental release of (toxic or radioactive) gases or particles into the atmosphere. In its operational version the model area will cover most of Europe. The main processes accounted for in the model are: relative diffusion by wind shear and turbulence, advection as a function of space and time, the diurnal cycle of boundary layer hei...

  8. Dispersion Models to Forecast Traffic-related Emissions in Urban Areas

    Directory of Open Access Journals (Sweden)

    Davide Scannapieco

    2011-11-01

    Full Text Available Down the centuries, a direct link had been developed between increase in mobility and increase in wealth. On the other hand, air emission of greenhouse gases (GHG due to vehicles equipped with internal combustion engines can be regarded as a negative pressure over the environment. In the coming decades, road transport is likely to remain a significant contributor to air pollution in cities. Many urban trips cover distances of less than 6 km. Since the effectiveness of catalytic converters in the initial minutes of engine operation is small, the average emission per distance driven is very high in urban areas. Also, poorly maintained vehicles that lack exhaust aftertreatment systems are responsible for a major part of pollutant emissions. Therefore in urban areas, where higher concentrations of vehicles can be easily found, air pollution represents a critical issue, being it related with both environment and human health protection: in truth, research in recent decades consistently indicates the adverse effects of outdoor air pollution on human health, and the evidence points to air pollution stemming from transport as an important contributor to these effects. Several institutions (EEA, USEPA, etc. focused their interest in dispersion models because of their potential effectiveness to forecast atmospheric pollution. Furthermore, air micropollutants such as Polycyclic Aromatic Compounds (PAH and Metallic Trace Elements (MTE are traffic-related and although very low concentrations their dispersion is a serious issue. However, dispersion models are usefully implemented to better manage this estimation problem. Nonetheless, policy makers and land managers have to deal with model selection, taking into account that several dispersion models are available, each one of them focused on specific goals (e.g., wind transport of pollutants, land morphology implementation, evaluation of micropollutants transport, etc.; a further aspect to be considered is

  9. The environmental radiological atmospheric impact modelling system (ERAIMS) at ANSTO, Lucas Heights

    International Nuclear Information System (INIS)

    Decision-makers managing the emergency response to an actual or potential release of airborne radionuclides from the Lucas Heights Science and Technology Centre (LHSTC) require real-time estimates of the trajectory and dispersion of any released radionuclides. Complex terrain surrounding the LHSTC has an impact on the downwind trajectory and atmospheric dispersion of released radionuclides. Under certain atmospheric conditions, the released cloud could be transported into the valley without direct impact on the nearest population. This entrapment in the steep sided, narrow valley, might mean that the cloud could remain more concentrated and cause impacts on more distant receptor populations down the valley. Alternatively, the cloud could disperse directly across the valley to the nearest residential population without any significant entrainment into, or impact, on the valley. The Environmental Radiological Atmospheric Impact Modelling System (ERAIMS) is a realtime response model which has been developed for the LHSTC. It estimates downwind impacts based on a pre-set source term, prevailing meteorological conditions which are measured every 15 minutes, receptor characteristics and exposure pathways. This paper describes the total system, from collection and calibration of meteorological data, to the running of the models in the ANSTO emergency response facility and display of data for controllers of any emergency. The current assessment of different atmospheric dispersion models available for use in this facility will also be discussed in terms of atmospheric tracer studies conducted in the region and International Best Practice. Copyright (2000) Australasian Radiation Protection Society Inc

  10. Dispersion of the impurity released from an instantaneous source in turbulent atmosphere

    Science.gov (United States)

    Balin, Yuri S.; Ershov, Arkadii D.; Bril, Andrey I.; Kabashnikov, Vitaliy P.; Popov, V. M.; Chaikovsky, Anatoly P.

    2002-02-01

    The results of comprehensive field experiment are presented. The objective of the experiment is lidar technique development for control of pollutant dispersion from pulse source. Experiment was carried out in steppe region, underlying surface was covered with sparse vegetation. Charge exploded at the altitude of 10 m stand for source of pollutant. Lidar was used to trace the cloud of explosion products. The ratio of backscatter signal from the cloud to aerosol background signal was recorded along with the time and coordinates of sounded points. Ultrasonic meteorological station and sodar 25 - 30 meters distant from explosion location were used to measure air temperature, vertical and horizontal components of wind velocity and its direction, total energy of turbulent motions, tangential turbulent friction stress and vertical turbulent heat flow. Experimental data were compared with the results of numerical modeling of pollutant spatial distribution performed on the basis of Gaussian statistical model. Numerical results were primarily in satisfactory agreement with experimental data.

  11. Spatial capture-recapture models allowing Markovian transience or dispersal

    Science.gov (United States)

    Royle, J. Andrew; Fuller, Angela K.; Sutherland, Chris

    2016-01-01

    Spatial capture–recapture (SCR) models are a relatively recent development in quantitative ecology, and they are becoming widely used to model density in studies of animal populations using camera traps, DNA sampling and other methods which produce spatially explicit individual encounter information. One of the core assumptions of SCR models is that individuals possess home ranges that are spatially stationary during the sampling period. For many species, this assumption is unlikely to be met and, even for species that are typically territorial, individuals may disperse or exhibit transience at some life stages. In this paper we first conduct a simulation study to evaluate the robustness of estimators of density under ordinary SCR models when dispersal or transience is present in the population. Then, using both simulated and real data, we demonstrate that such models can easily be described in the BUGS language providing a practical framework for their analysis, which allows us to evaluate movement dynamics of species using capture–recapture data. We find that while estimators of density are extremely robust, even to pathological levels of movement (e.g., complete transience), the estimator of the spatial scale parameter of the encounter probability model is confounded with the dispersal/transience scale parameter. Thus, use of ordinary SCR models to make inferences about density is feasible, but interpretation of SCR model parameters in relation to movement should be avoided. Instead, when movement dynamics are of interest, such dynamics should be parameterized explicitly in the model.

  12. ATMOSPHERIC HEALTH EFFECTS FRAMEWORK (AHEF) MODEL

    Science.gov (United States)

    The Atmospheric and Health Effects Framework (AHEF) is used to assess theglobal impacts of substitutes for ozone-depleting substances (ODS). The AHEF is a series of FORTRAN modeling modules that collectively form a simulation framework for (a) translating ODS production into emi...

  13. Modelling stable atmospheric boundary layers over snow

    NARCIS (Netherlands)

    Sterk, H.A.M.

    2015-01-01

    Thesis entitled: Modelling Stable Atmospheric Boundary Layers over Snow H.A.M. Sterk Wageningen, 29th of April, 2015 Summary The emphasis of this thesis is on the understanding and forecasting of the Stable Boundary Layer (SBL) over snow-covered surfaces. SBLs typically form at night and in polar re

  14. Puff models for simulation of fugitive radioactive emissions in atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Camila P. da, E-mail: camila.costa@ufpel.edu.b [Universidade Federal de Pelotas (UFPel), RS (Brazil). Inst. de Fisica e Matematica. Dept. de Matematica e Estatistica; Pereira, Ledina L., E-mail: ledinalentz@yahoo.com.b [Universidade do Extremo Sul Catarinense (UNESC), Criciuma, SC (Brazil); Vilhena, Marco T., E-mail: vilhena@pq.cnpq.b [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Engenharia Mecanica; Tirabassi, Tiziano, E-mail: t.tirabassi@isac.cnr.i [Institute of Atmospheric Sciences and Climate (CNR/ISAC), Bologna (Italy)

    2009-07-01

    A puff model for the dispersion of material from fugitive radioactive emissions is presented. For vertical diffusion the model is based on general techniques for solving time dependent advection-diffusion equation: the ADMM (Advection Diffusion Multilayer Method) and GILTT (Generalized Integral Laplace Transform Technique) techniques. The first one is an analytical solution based on a discretization of the Atmospheric Boundary Layer (ABL) in sub-layers where the advection-diffusion equation is solved by the Laplace transform technique. The solution is given in integral form. The second one is a well-known hybrid method that had solved a wide class of direct and inverse problems mainly in the area of Heat Transfer and Fluid Mechanics and the solution is given in series form. Comparisons between values predicted by the models against experimental ground-level concentrations are shown. (author)

  15. Transverse nonlinear instability for two-dimensional dispersive models

    OpenAIRE

    Rousset, F.; N. Tzvetkov

    2006-01-01

    We present a method to prove nonlinear instability of solitary waves in dispersive models. Two examples are analyzed: we prove the nonlinear long time instability of the KdV solitary wave (with respect to periodic transverse perturbations) under a KP-I flow and the transverse nonlinear instability of solitary waves for the cubic nonlinear Schr\\"odinger equation.

  16. Fuel dispersal modeling for aircraft-runway impact scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Tieszen, S.R.

    1995-11-01

    A fuel dispersal model for C-141 transport accidents was developed for the Defense Nuclear Agency`s Fuel Fire Technology Base Program to support Weapon System Safety Assessments. The spectrum of accidents resulting from aircraft impact on a runway was divided into three fuel dispersal regimes: low, intermediate, and high-velocity impact. Sufficient data existed in the accident, crash test, and fuel-filled bomb literature to support development of a qualitative framework for dispersal models, but not quantitative models for all regimes. Therefore, a test series at intermediate scale was conducted to generate data on which to base the model for the high-velocity regime. Tests were conducted over an impact velocity range from 12 m/s to 91 m/s and angles of impact from 22.5{degrees} to 67.5{degrees}. Dependent variables were area covered by dispersed fuel, amount of mass in that area, and location of the area relative to the impact line. Test results showed that no liquid pooling occurred for impact velocities greater than 61 m/s, independent of the angle of impact. Some pooling did occur at lower velocities, but in no test was the liquid-layer thickness greater than 5.25 mm.

  17. Exposure estimates using urban plume dispersion and traffic microsimulation models

    Energy Technology Data Exchange (ETDEWEB)

    Brown, M.J.; Mueller, C.; Bush, B.; Stretz, P.

    1997-12-01

    The goal of this research effort was to demonstrate a capability for analyzing emergency response issues resulting from accidental or mediated airborne toxic releases in an urban setting. In the first year of the program, the authors linked a system of fluid dynamics, plume dispersion, and vehicle transportation models developed at Los Alamos National Laboratory to study the dispersion of a plume in an urban setting and the resulting exposures to vehicle traffic. This research is part of a larger laboratory-directed research and development project for studying the relationships between urban infrastructure elements and natural systems.

  18. CFD modeling of dust dispersion through Najaf historic city centre

    Directory of Open Access Journals (Sweden)

    Maher A.R. Sadiq Al-Baghdadi

    2014-01-01

    Full Text Available The aim of this project is to study the influences of the wind flow and dust particles dispersion through Najaf historic city centre. Two phase Computational Fluid Dynamics (CFD model using a Reynolds Average Navier Stokes (RANS equations has been used to simulate the wind flow and the transport and dispersion of the dust particles through the historic city centre. This work may provide useful insight to urban designers and planners interested in examining the variation of city breathability as a local dynamic morphological parameter with the local building packing density.

  19. PIV Measurements of Atmospheric Turbulence and Pollen Dispersal Above a Corn Canopy

    Science.gov (United States)

    Zhu, W.; van Hout, R.; Luznik, L.; Katz, J.

    2003-12-01

    Dispersal of pollen grains by wind and gravity (Anemophilous) is one of the oldest means of plant fertilization available in nature. Recently, the growth of genetically modified foods has raised questions on the range of pollen dispersal in order to limit cross-fertilization between organically grown and transgenic crops. The distance that a pollen grain can travel once released from the anther is determined, among others, by the aerodynamic parameters of the pollen and the characteristics of turbulence in the atmosphere in which it is released. Turbulence characteristics of the flow above a pollinating corn field were measured using Particle Image Velocimetry (PIV). The measurements were performed on the eastern shore of the Chesapeake Bay, in Maryland, during July 2003. Two PIV systems were used simultaneously, each with an overall sample area of 18x18 cm. The spacing between samples was about equal to the field of view. The PIV instrumentation, including CCD cameras, power supply and laser sheets forming optics were mounted on a measurement platform, consisting of a hydraulic telescopic arm that could be extended up to 10m. The whole system could be rotated in order to align it with the flow. The flow was seeded with smoke generated about 30m upstream of the sample areas. Measurements were carried out at several elevations, from just below canopy height up to 1m above canopy. The local meteorological conditions around the test site were monitored by other sensors including sonic anemometers, Rotorod pollen counters and temperature sensors. Each processed PIV image provides an instantaneous velocity distribution containing 64x64 vectors with a vector spacing of ~3mm. The pollen grains (~100mm) can be clearly distinguished from the smoke particles (~1mm) based on their size difference. The acquired PIV data enables calculation of the mean flow and turbulence characteristics including Reynolds stresses, spectra, turbulent kinetic energy and dissipation rate. Data

  20. Validation data for models of contaminant dispersal : scaling laws and data needs.

    Energy Technology Data Exchange (ETDEWEB)

    O' Hern, Timothy John; Ceccio, Steven Louis (University of Michigan, Ann Arbor, MI)

    2004-09-01

    Contaminant dispersal models for use at scales ranging from meters to miles are widely used for planning sensor locations, first-responder actions for release scenarios, etc. and are constantly being improved. Applications range from urban contaminant dispersal to locating buried targets from an exhaust signature. However, these models need detailed data for model improvement and validation. A small Sandia National Laboratories Laboratory Directed Research and Development (LDRD) program was funded in FY04 to examine the feasibility and usefulness of a scale-model capability for quantitative characterization of flow and contaminant dispersal in complex environments. This report summarizes the work performed in that LDRD. The basics of atmospheric dispersion and dispersion modeling are reviewed. We examine the need for model scale data, and the capability of existing model test methods. Currently, both full-scale and model scale experiments are performed in order to collect validation data for numerical models. Full-scale experiments are expensive, are difficult to repeat, and usually produce relatively sparse data fields. Model scale tests often employ wind tunnels, and the data collected is, in many cases, derived from single point measurements. We review the scaling assumptions and methods that are used to relate model and full scale flows. In particular, we examine how liquid flows may be used to examine the process of atmospheric dispersion. The scaling between liquid and gas flows is presented. Use of liquid as the test fluid has some advantages in terms of achieving fully turbulent Reynolds numbers and in seeding the flow with neutrally buoyant tracer particles. In general, using a liquid flow instead of a gas flow somewhat simplifies the use of full field diagnostics, such as Particle Image Velocimetry and Laser Induced Fluorescence. It is also possible to create stratified flows through mixtures of fluids (e.g., water, alcohol, and brine). Lastly, we

  1. Dispersion modeling of selected PAHs in urban air: A new approach combining dispersion model with GIS and passive air sampling

    Science.gov (United States)

    Sáňka, Ondřej; Melymuk, Lisa; Čupr, Pavel; Dvorská, Alice; Klánová, Jana

    2014-10-01

    This study introduces a new combined air concentration measurement and modeling approach that we propose can be useful in medium and long term air quality assessment. A dispersion study was carried out for four high molecular weight polycyclic aromatic hydrocarbons (PAHs) in an urban area with industrial, traffic and domestic heating sources. A geographic information system (GIS) was used both for processing of input data as well as visualization of the modeling results. The outcomes of the dispersion model were compared to the results of passive air sampling (PAS). Despite discrepancies between measured and modeled concentrations, an approach combining the two techniques is promising for future air quality assessment. Differences between measured and modeled concentrations, in particular when measured values exceed the modeled concentrations, are indicative of undocumented, sporadic pollutant sources. Thus, these differences can also be useful for assessing and refining emission inventories.

  2. A linearized dispersion relation for orthorhombic pseudo-acoustic modeling

    KAUST Repository

    Song, Xiaolei

    2012-11-04

    Wavefield extrapolation in acoustic orthorhombic anisotropic media suffers from wave-mode coupling and stability limitations in the parameter range. We introduce a linearized form of the dispersion relation for acoustic orthorhombic media to model acoustic wavefields. We apply the lowrank approximation approach to handle the corresponding space-wavenumber mixed-domain operator. Numerical experiments show that the proposed wavefield extrapolator is accurate and practically free of dispersions. Further, there is no coupling of qSv and qP waves, because we use the analytical dispersion relation. No constraints on Thomsen\\'s parameters are required for stability. The linearized expression may provide useful application for parameter estimation in orthorhombic media.

  3. Mathematical modeling of non-stationary heat and mass transfer in disperse systems

    Science.gov (United States)

    Ermakova, L. A.; Krasnoperov, S. Y.; Kalashnikov, S. N.

    2016-09-01

    The work describes mathematical model of non-stationary heat and mass transfer processes in dispersed environment, taking into account the phase transition; presents the results of numeric modelling for conditions of direct reduction in high-temperature reducing atmosphere, corresponding to the direct reduction in the jet-emulsion unit according to the principles of self-organization. The method was developed for calculation of heat and mass transfer of the aggregate of iron material particles in accordance with the given distribution law.

  4. Global Atmospheric Models for Cosmic Ray Detectors

    CERN Document Server

    Will, Martin

    2014-01-01

    The knowledge of atmospheric parameters -- such as temperature, pressure, and humidity -- is very important for a proper reconstruction of air showers, especially with the fluorescence technique. The Global Data Assimilation System (GDAS) provides altitude-dependent profiles of these state variables of the atmosphere and several more. Every three hours, a new data set on 23 constant pressure level plus an additional surface values is available for the entire globe. These GDAS data are now used in the standard air shower reconstruction of the Pierre Auger Observatory. The validity of the data was verified by comparisons with monthly models that were averaged from on-site meteorological radio soundings and weather station measurements obtained at the Observatory in Malarg\\"ue. Comparisons of reconstructions using the GDAS data and the monthly models are also presented. Since GDAS is a global model, the data can potentially be used for other cosmic and gamma ray detectors. Several studies were already performed ...

  5. Comparison of turbulent particle dispersion models in turbulent shear flows

    Directory of Open Access Journals (Sweden)

    S. Laín

    2007-09-01

    Full Text Available This work compares the performance of two Lagrangian turbulent particle dispersion models: the standard model (e.g., that presented in Sommerfeld et al. (1993, in which the fluctuating fluid velocity experienced by the particle is composed of two components, one correlated with the previous time step and a second one randomly sampled from a Wiener process, and the model proposed by Minier and Peirano (2001, which is based on the PDF approach and performs closure at the level of acceleration of the fluid experienced by the particle. Formulation of a Langevin equation model for the increments of fluid velocity seen by the particle allows capturing some underlying physics of particle dispersion in general turbulent flows while keeping the mathematical manipulation of the stochastic model simple, thereby avoiding some pitfalls and simplifying the derivation of macroscopic relations. The performance of both dispersion models is tested in the configurations of grid-generated turbulence (Wells and Stock (1983 experiments, simple shear flow (Hyland et al., 1999 and confined axisymmetric jet flow laden with solids (Hishida and Maeda (1987 experiments.

  6. A multiscale model for bioimpedance dispersion of liver tissue.

    Science.gov (United States)

    Huang, W H; Chui, C K; Teoh, S H; Chang, S K Y

    2012-06-01

    Radio-frequency ablation (RFA) has been used in liver surgery to minimize blood loss during tissue division. However, the current RFA tissue division method lacks an effective way of determining the stoppage of blood flow. There is limitation on the current state-of-the-art laser Doppler flow sensor due to its small sensing area. A new technique was proposed to use bioimpedance for blood flow sensing. This paper discusses a new geometrical multiscale model of the liver bioimpedance incorporating blood flow impedance. This model establishes correlation between the physical tissue structure and bioimpedance measurement. The basic Debye structure within a multilevel framework is used in the model to account for bioimpedance dispersion. This dispersion is often explained by the Cole-Cole model that includes a constant phase element without physical explanation. Our model is able to account for reduced blood flow in its output with changes in permittivity in gamma dispersion that is mainly due to the polarization of water molecules. This study demonstrates the potential of a multiscale model in determining the stoppage of blood flow during surgery.

  7. Applicability of an integrated plume rise model for the dispersion from wild-land fires

    Directory of Open Access Journals (Sweden)

    J. Kukkonen

    2014-01-01

    Full Text Available We have presented an overview of a mathematical model, BUOYANT, that was originally designed for the evaluation of the dispersion of buoyant plumes originated from major warehouse fires. The model addresses the variations of the cross-plume integrated properties of a buoyant plume in the presence of a vertically varying atmosphere. The model also includes a treatment for a rising buoyant plume interacting with an inversion layer. We have compared the model predictions with the data of two prescribed wild-land fire experiments. For the SCAR-C experiment in Quinault (US in 1994, the predicted vertical extents of the plume at maximum plume rise were between 500–800 m and 200–700 m, using two alternative meteorological datasets. The corresponding observed injection heights of the aerosol particles measured using an airborne LIDAR (LIght Detection And Ranging ranged from 250 and 600 m. For the prescribed burning experiment in Hyytiälä (Finland in 2009, the model predictions were compared with plume elevations and diameters, determined based on particulate matter number concentration measurements on board an aeroplane. The agreement of modelled and measured results was good, provided that one assumes the measured maximum convective heat fluxes as input data for the model. The results demonstrate that in field experiments on wild-land fires, there are substantial uncertainties in estimating both (i the source terms for the atmospheric dispersion computations, and (ii the relevant vertical meteorological profiles. The results provide more confidence that cross-plume integrated mathematical models, such as the BUOYANT model, can be used to fairly good accuracy for evaluating the dispersion from major wild-land fires.

  8. Validation of the DIFFAL, HPAC and HotSpot Dispersion Models Using the Full-Scale Radiological Dispersal Device (FSRDD) Field Trials Witness Plate Deposition Dataset.

    Science.gov (United States)

    Purves, Murray; Parkes, David

    2016-05-01

    Three atmospheric dispersion models--DIFFAL, HPAC, and HotSpot--of differing complexities have been validated against the witness plate deposition dataset taken during the Full-Scale Radiological Dispersal Device (FSRDD) Field Trials. The small-scale nature of these trials in comparison to many other historical radiological dispersion trials provides a unique opportunity to evaluate the near-field performance of the models considered. This paper performs validation of these models using two graphical methods of comparison: deposition contour plots and hotline profile graphs. All of the models tested are assessed to perform well, especially considering that previous model developments and validations have been focused on larger-scale scenarios. Of the models, HPAC generally produced the most accurate results, especially at locations within ∼100 m of GZ. Features present within the observed data, such as hot spots, were not well modeled by any of the codes considered. Additionally, it was found that an increase in the complexity of the meteorological data input to the models did not necessarily lead to an improvement in model accuracy; this is potentially due to the small-scale nature of the trials.

  9. Effects of vertical shear in modelling horizontal oceanic dispersion

    Science.gov (United States)

    Lanotte, A. S.; Corrado, R.; Palatella, L.; Pizzigalli, C.; Schipa, I.; Santoleri, R.

    2016-02-01

    The effect of vertical shear on the horizontal dispersion properties of passive tracer particles on the continental shelf of the South Mediterranean is investigated by means of observation and model data. In situ current measurements reveal that vertical gradients of horizontal velocities in the upper mixing layer decorrelate quite fast ( ˜ 1 day), whereas an eddy-permitting ocean model, such as the Mediterranean Forecasting System, tends to overestimate such decorrelation time because of finite resolution effects. Horizontal dispersion, simulated by the Mediterranean sea Forecasting System, is mostly affected by: (1) unresolved scale motions, and mesoscale motions that are largely smoothed out at scales close to the grid spacing; (2) poorly resolved time variability in the profiles of the horizontal velocities in the upper layer. For the case study we have analysed, we show that a suitable use of deterministic kinematic parametrizations is helpful to implement realistic statistical features of tracer dispersion in two and three dimensions. The approach here suggested provides a functional tool to control the horizontal spreading of small organisms or substance concentrations, and is thus relevant for marine biology, pollutant dispersion as well as oil spill applications.

  10. Applicability of an integrated plume rise model for the dispersion from wild-land fires

    Science.gov (United States)

    Kukkonen, J.; Nikmo, J.; Sofiev, M.; Riikonen, K.; Petäjä, T.; Virkkula, A.; Levula, J.; Schobesberger, S.; Webber, D. M.

    2014-11-01

    We have presented an overview of a mathematical model, BUOYANT, that was originally designed for the evaluation of the dispersion of buoyant plumes originated from major warehouse fires. The model addresses the variations of the cross-plume integrated properties of a buoyant plume in the presence of a vertically varying atmosphere. The model also includes a treatment for a rising buoyant plume interacting with an inversion layer. We have compared the model predictions with the data of two prescribed wild-land fire experiments. For the SCAR-C experiment in Quinault (US) in 1994, the predicted vertical extents of the plume at maximum plume rise were between 500 and 800 m and between 200 and 700 m, using two alternative meteorological data sets. The corresponding observed injection heights of the aerosol particles measured using an airborne lidar (light detection and ranging) ranged from 250 to 600 m. For the prescribed burning experiment in Hyytiälä (Finland) in 2009, the model predictions were compared with plume elevations and diameters, determined based on particulate matter number concentration measurements onboard an aeroplane. However, the agreement between modelled and measured results substantially depends on how the properties of the source term are evaluated, especially regarding the convective heat fluxes from the fire. The results demonstrate that in field experiments on wild-land fires, there are substantial uncertainties in estimating both (i) the source terms for the atmospheric dispersion computations and (ii) the relevant vertical meteorological profiles.

  11. A Global Atmospheric Model of Meteoric Iron

    Science.gov (United States)

    Feng, Wuhu; Marsh, Daniel R.; Chipperfield, Martyn P.; Janches, Diego; Hoffner, Josef; Yi, Fan; Plane, John M. C.

    2013-01-01

    The first global model of meteoric iron in the atmosphere (WACCM-Fe) has been developed by combining three components: the Whole Atmosphere Community Climate Model (WACCM), a description of the neutral and ion-molecule chemistry of iron in the mesosphere and lower thermosphere (MLT), and a treatment of the injection of meteoric constituents into the atmosphere. The iron chemistry treats seven neutral and four ionized iron containing species with 30 neutral and ion-molecule reactions. The meteoric input function (MIF), which describes the injection of Fe as a function of height, latitude, and day, is precalculated from an astronomical model coupled to a chemical meteoric ablation model (CABMOD). This newly developed WACCM-Fe model has been evaluated against a number of available ground-based lidar observations and performs well in simulating the mesospheric atomic Fe layer. The model reproduces the strong positive correlation of temperature and Fe density around the Fe layer peak and the large anticorrelation around 100 km. The diurnal tide has a significant effect in the middle of the layer, and the model also captures well the observed seasonal variations. However, the model overestimates the peak Fe+ concentration compared with the limited rocket-borne mass spectrometer data available, although good agreement on the ion layer underside can be obtained by adjusting the rate coefficients for dissociative recombination of Fe-molecular ions with electrons. Sensitivity experiments with the same chemistry in a 1-D model are used to highlight significant remaining uncertainties in reaction rate coefficients, and to explore the dependence of the total Fe abundance on the MIF and rate of vertical transport.

  12. Network models of frugivory and seed dispersal: Challenges and opportunities

    Science.gov (United States)

    Carlo, Tomás A.; Yang, Suann

    2011-11-01

    Network analyses have emerged as a new tool to study frugivory and seed dispersal (FSD) mutualisms because networks can model and simplify the complexity of multiple community-wide species interactions. Moreover, network theory suggests that structural properties, such as the presence of highly generalist species, are linked to the stability of mutualistic communities. However, we still lack empirical validation of network model predictions. Here we outline new research avenues to connect network models to FSD processes, and illustrate the challenges and opportunities of this tool with a field study. We hypothesized that generalist frugivores would be important for forest stability by dispersing seeds into deforested areas and initiating reforestation. We then constructed a network of plant-frugivore interactions using published data and identified the most generalist frugivores. To test the importance of generalists we measured: 1) the frequency with which frugivores moved between pasture and forest, 2) the bird-generated seed rain under perches in the pasture, and 3) the perching frequency of birds above seed traps. The generalist frugivores in the forest network were not important for seed dispersal into pastures, and thus for forest recovery, because the forest network excluded habitat heterogeneities, frugivore behavior, and movements. More research is needed to develop ways to incorporate relevant FSD processes into network models in order for these models to be more useful to community ecology and conservation. The network framework can serve to spark and renew interest in FSD and further our understanding of plant-animal communities.

  13. Thermal conductivity modeling of U-Mo/Al dispersion fuel

    Science.gov (United States)

    Kim, Yeon Soo; Cho, Byoung Jin; Sohn, Dong-Seong; Park, Jong Man

    2015-11-01

    A dataset for the thermal conductivity of U-Mo/Al dispersion fuel made available by KAERI was reanalyzed. Using this dataset, an analytical model was obtained by expanding the Bruggeman model. The newly developed model incorporates thermal resistances at the interface between the U-Mo particles and the Al matrix and the defects within the Al matrix (grain boundaries, cracks, and dislocations). The interfacial resistances are expressed as functions of U-Mo particle size and Al grain size obtained empirically by fitting to measured data from KAERI. The model was then validated against an independently measured dataset from ANL.

  14. Generalized uniform formulae for atmospheric dispersion of activities released from a ventilation stack or from a leaky reactor building

    International Nuclear Information System (INIS)

    Relations are given for the calculation of the atmospheric transport and dispersion of industrial gaseous wastes released from the stacks of factories, power plants and nuclear power plants. Modified formulae are derived for stack disposal from a small stack, also applicable in calculating the gaseous waste release from a leaky reactor. Uniform generalized formulae are presented serving the calculation of both high and short stack disposals as well as of reactor building leakages. (L.O.)

  15. Climate change and climate systems influence and control the atmospheric dispersion of desert dust: implications for human health

    Science.gov (United States)

    Griffin, Dale W.

    2010-01-01

    The global dispersion of desert dust through Earth’s atmosphere is greatly influenced by temperature. Temporal analyses of ice core data have demonstrated that enhanced dust dispersion occurs during glacial events. This is due to an increase in ice cover, which results in an increase in drier terrestrial cover. A shorter temporal analysis of dust dispersion data over the last 40 years has demonstrated an increase in dust transport. Climate systems or events such as the North Atlantic Oscillation, the Indian Ocean subtropical High, Pacific Decadal Oscillation, and El Nino-Sothern Oscillation are known to influence global short-term dust dispersion occurrence and transport routes. Anthropogenic influences on dust transport include deforestation, harmful use of topsoil for agriculture as observed during the American Dust Bowl period, and the creation of dry seas (Aral Sea) and lakes (Lake Owens in California and Lake Chad in North Africa) through the diversion of source waters (for irrigation and drinking water supplies). Constituents of desert dust both from source regions (pathogenic microorganisms, organic and inorganic toxins) and those scavenged through atmospheric transport (i.e., industrial and agricultural emissions) are known to directly impact human and ecosystem health. This presentation will present a review of global scale dust storms and how these events can be both a detriment and benefit to various organisms in downwind environments.

  16. Development of an advanced atmospheric/transport model for emergency response purposes

    International Nuclear Information System (INIS)

    Atmospheric transport and diffusion models have been developed for real-time calculations of the location and concentration of toxic or radioactive materials during an accidental release at the Savannah River Site (SRS). These models are based Gaussian distributions and have been incorporated into an automated menu-driven program called the WIND (Weather INformation and Display) system. The WIND system atmospheric models employ certain assumptions that allow the computations of the ground-level concentration of toxic or radioactive materials to be made quickly. Gaussian models, such as PF/PL and 2DPUF, suffer from serious limitations including the inability to represent recirculation of pollutants in complex terrain, the use of one stability class at a given time to represent turbulent mixing over heterogeneous terrain, and the use of a wind field computed at only one height in the atmosphere. These limitations arise because the fundamental conservation relations of the atmosphere have been grossly simplified. Three-dimensional coupled atmospheric-dispersion models are not limited by the over-simplifications of the Gaussian assumption and have been used in the past to predict the transport of pollutants in a variety of atmospheric circulations. The disadvantage of these models is that they require large amounts of computational time; however, technology has progressed enough so that real-time simulations of dispersion may be made. These complex models can be run in an operational mode so that routine forecasts of the wind field and particulate concentration can be made

  17. Centrifuge modeling of soil atmosphere interaction

    OpenAIRE

    CAICEDO, B; TRISTANCHO, J; THOREL, Luc

    2010-01-01

    Atmosphere process of infiltration or evaporation affect the behavior of geotechnical structures located near the soil surface. This paper focuses on the drying process of soils due to evaporation. The scaling laws are analyzed and afterwards the results on applying two cycles of heating and cooling on a soil mass are presented. Based on these results, conclusions about the feasibility of reproducing evaporation on centrifuge models are recommended.

  18. CFD Modeling of LNG Spill: Humidity Effect on Vapor Dispersion

    Science.gov (United States)

    Giannissi, S. G.; Venetsanos, A. G.; Markatos, N.

    2015-09-01

    The risks entailed by an accidental spill of Liquefied Natural Gas (LNG) should be indentified and evaluated, in order to design measures for prevention and mitigation in LNG terminals. For this purpose, simulations are considered a useful tool to study LNG spills and to understand the mechanisms that influence the vapor dispersion. In the present study, the ADREA-HF CFD code is employed to simulate the TEEX1 experiment. The experiment was carried out at the Brayton Fire Training Field, which is affiliated with the Texas A&M University system and involves LNG release and dispersion over water surface in open- obstructed environment. In the simulation the source was modeled as a two-phase jet enabling the prediction of both the vapor dispersion and the liquid pool spreading. The conservation equations for the mixture are solved along with the mass fraction for natural gas. Due to the low prevailing temperatures during the spill ambient humidity condenses and this might affect the vapor dispersion. This effect was examined in this work by solving an additional conservation equation for the water mass fraction. Two different models were tested: the hydrodynamic equilibrium model which assumes kinetic equilibrium between the phases and the non hydrodynamic equilibrium model, in order to assess the effect of slip velocity on the prediction. The slip velocity is defined as the difference between the liquid phase and the vapor phase and is calculated using the algebraic slip model. Constant droplet diameter of three different sizes and a lognormal distribution of the droplet diameter were applied and the results are discussed and compared with the measurements.

  19. Dispersion Relations for Electroweak Observables in Composite Higgs Models

    CERN Document Server

    Contino, Roberto

    2015-01-01

    We derive dispersion relations for the electroweak oblique observables measured at LEP in the context of $SO(5)/SO(4)$ composite Higgs models. It is shown how these relations can be used and must be modified when modeling the spectral functions through a low-energy effective description of the strong dynamics. The dispersion relation for the parameter $\\epsilon_3$ is then used to estimate the contribution from spin-1 resonances at the 1-loop level. Finally, it is shown that the sign of the contribution to the $\\hat S$ parameter from the lowest-lying spin-1 states is not necessarily positive definite, but depends on the energy scale at which the asymptotic behavior of current correlators is attained.

  20. How realistic are solar model atmospheres?

    CERN Document Server

    Pereira, Tiago M D; Collet, Remo; Thaler, Irina; Trampedach, Regner; Leenaarts, Jorrit

    2013-01-01

    Recently, new solar model atmospheres have been developed to replace classical 1D LTE hydrostatic models and used to for example derive the solar chemical composition. We aim to test various models against key observational constraints. In particular, a 3D model used to derive the solar abundances, a 3D MHD model (with an imposed 10 mT vertical magnetic field), 1D models from the PHOENIX project, the 1D MARCS model, and the 1D semi-empirical model of Holweger & M\\"uller. We confront the models with observational diagnostics of the temperature profile: continuum centre-to-limb variations (CLV), absolute continuum fluxes, and the wings of hydrogen lines. We also test the 3D models for the intensity distribution of the granulation and spectral line shapes. The predictions from the 3D model are in excellent agreement with the continuum CLV observations, performing even better than the Holweger & M\\"uller model (constructed largely to fulfil such observations). The predictions of the 1D theoretical models ...

  1. A Method of Evaluating Atmospheric Models Using Tracer Measurements.

    Science.gov (United States)

    Korain, Darko; Frye, James; Isakov, Vlad

    2000-02-01

    The authors have developed a method that uses tracer measurements as the basis for comparing and evaluating wind fields. An important advantage of the method is that the wind fields are evaluated from the tracer measurements without introducing dispersion calculations. The method can be applied to wind fields predicted by different atmospheric models or to wind fields obtained from interpolation and extrapolation of measured data. The method uses a cost function to quantify the success of wind fields in representing tracer transport. A cost function, `tracer potential,' is defined to account for the magnitude of the tracer concentration at the tracer receptors and the separation between each segment of a trajectory representing wind field transport and each of the tracer receptors. The tracer potential resembles a general expression for a physical potential because the success of a wind field trajectory is directly proportional to the magnitude of the tracer concentration and inversely proportional to its distance from this concentration. A reference tracer potential is required to evaluate the relative success of the wind fields and is defined by the initial location of any trajectory at the source. Then the method is used to calculate continuously the tracer potential along each trajectory as determined by the wind fields in time and space. Increased potential relative to the reference potential along the trajectory indicates good performance of the wind fields and vice versa. If there is sufficient spatial coverage of near and far receptors around the source, then the net tracer potential area can be used to infer the overall success of the wind fields. If there are mainly near-source receptors, then the positive tracer potential area should be used. If the vertical velocity of the wind fields is not available, then the success of the wind fields can be estimated from the vertically integrated area under the tracer potential curve. A trajectory with a maximum

  2. Observations and Modeling of Tropical Planetary Atmospheres

    Science.gov (United States)

    Laraia, Anne

    2016-01-01

    This thesis is a comprised of three different projects within the topic of tropical atmospheric dynamics. First, I analyze observations of thermal radiation from Saturn's atmosphere and from them, determine the latitudinal distribution of ammonia vapor near the 1.5-bar pressure level. The most prominent feature of the observations is the high brightness temperature of Saturn's subtropical latitudes on either side of the equator. After comparing the observations to a microwave radiative transfer model, I find that these subtropical bands require very low ammonia relative humidity below the ammonia cloud layer in order to achieve the high brightness temperatures observed. We suggest that these bright subtropical bands represent dry zones created by a meridionally overturning circulation. Second, I use a dry atmospheric general circulation model to study equatorial superrotation in terrestrial atmospheres. A wide range of atmospheres are simulated by varying three parameters: the pole-equator radiative equilibrium temperature contrast, the convective lapse rate, and the planetary rotation rate. A scaling theory is developed that establishes conditions under which superrotation occurs in terrestrial atmospheres. The scaling arguments show that superrotation is favored when the off-equatorial baroclinicity and planetary rotation rates are low. Similarly, superrotation is favored when the convective heating strengthens, which may account for the superrotation seen in extreme global-warming simulations. Third, I use a moist slab-ocean general circulation model to study the impact of a zonally-symmetric continent on the distribution of monsoonal precipitation. I show that adding a hemispheric asymmetry in surface heat capacity is sufficient to cause symmetry breaking in both the spatial and temporal distribution of precipitation. This spatial symmetry breaking can be understood from a large-scale energetic perspective, while the temporal symmetry breaking requires

  3. Wage Dispersion in the Search and Matching Model

    OpenAIRE

    Dale T. Mortensen

    2010-01-01

    Matched employer-employee data exhibits both wage and productivity dispersion across firms and suggest that a linear relationship holds between the average wage paid and a firm productivity. The purpose of this paper is to demonstrate that these facts can be explained by a search and matching model when firms are heterogenous with respect to productivity, are composed of many workers, and face diminishing returns to labor given the wage paid to identical workers is the solution to the Stole-Z...

  4. Seasonal Predictability in a Model Atmosphere.

    Science.gov (United States)

    Lin, Hai

    2001-07-01

    The predictability of atmospheric mean-seasonal conditions in the absence of externally varying forcing is examined. A perfect-model approach is adopted, in which a global T21 three-level quasigeostrophic atmospheric model is integrated over 21 000 days to obtain a reference atmospheric orbit. The model is driven by a time-independent forcing, so that the only source of time variability is the internal dynamics. The forcing is set to perpetual winter conditions in the Northern Hemisphere (NH) and perpetual summer in the Southern Hemisphere.A significant temporal variability in the NH 90-day mean states is observed. The component of that variability associated with the higher-frequency motions, or climate noise, is estimated using a method developed by Madden. In the polar region, and to a lesser extent in the midlatitudes, the temporal variance of the winter means is significantly greater than the climate noise, suggesting some potential predictability in those regions.Forecast experiments are performed to see whether the presence of variance in the 90-day mean states that is in excess of the climate noise leads to some skill in the prediction of these states. Ensemble forecast experiments with nine members starting from slightly different initial conditions are performed for 200 different 90-day means along the reference atmospheric orbit. The serial correlation between the ensemble means and the reference orbit shows that there is skill in the 90-day mean predictions. The skill is concentrated in those regions of the NH that have the largest variance in excess of the climate noise. An EOF analysis shows that nearly all the predictive skill in the seasonal means is associated with one mode of variability with a strong axisymmetric component.

  5. Atmospheric Dispersion at Spatial Resolutions Below Mesoscale for university of Tennessee SimCenter at Chattanooga: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Dr. David Whitfield; Dr. Daniel Hyams

    2009-09-14

    In Year 1 of this project, items 1.1 and 1.2 were addressed, as well as item 2.2. The baseline parallel computational simulation tool has been refined significantly over the timeline of this project for the purpose of atmospheric dispersion and transport problems; some of these refinements are documented in Chapter 3. The addition of a concentration transport capability (item 1.2) was completed, along with validation and usage in a highly complex urban environment. Multigrid capability (item 2.2) was a primary focus of Year 1 as well, regardless of the fact that it was scheduled for Year 2. It was determined by the authors that due to the very large nature of the meshes required for atmospheric simulations at mesoscale, multigrid was a key enabling technology for the rest of the project to be successful. Therefore, it was addressed early according to the schedule laid out in the original proposal. The technology behind the multigrid capability is discussed in detail in Chapter 5. Also in Year 1, the issue of ground topography specification is addressed. For simulations of pollutant transport in a given region, a key prerequisite is the specification of the detailed ground topography. The local topography must be placed into a form suitable for generating an unstructured grid both on the topography itself and the atmospheric volume above it; this effort is documented in Chapter 6. In Year 2 of this project, items 1.3 and 2.1 were addressed. Weather data in the form of wind speeds, relative humidity, and baseline pollution levels may be input into the code in order to improve the real-world fidelity of the solutions. Of course, the computational atmospheric boundary layer (ABL) boundary condition developed in Year 1 may still be used when necessary. Cloud cover may be simulated via the levels of actinic flux allowed in photochemical reactions in the atmospheric chemistry model. The primary focus of Year 2 was the formulation of a multispecies capability with included

  6. Regional forecasting with global atmospheric models

    International Nuclear Information System (INIS)

    This report was prepared by the Applied Research Corporation (ARC), College Station, Texas, under subcontract to Pacific Northwest Laboratory (PNL) as part of a global climate studies task. The task supports site characterization work required for the selection of a potential high-level nuclear waste repository and is part of the Performance Assessment Scientific Support (PASS) Program at PNL. The work is under the overall direction of the Office of Civilian Radioactive Waste Management (OCRWM), US Department of Energy Headquarters, Washington, DC. The scope of the report is to present the results of the third year's work on the atmospheric modeling part of the global climate studies task. The development testing of computer models and initial results are discussed. The appendices contain several studies that provide supporting information and guidance to the modeling work and further details on computer model development. Complete documentation of the models, including user information, will be prepared under separate reports and manuals

  7. NKS NordRisk. Atlas of long-range atmospheric dispersion and deposition of radionuclides from selected risk sites in the Northern Hemisphere

    Energy Technology Data Exchange (ETDEWEB)

    Havskov Soerensen, J.; Baklanov, A.; Mahura, A. (Danish Meteorological Institute, Copenhagen (Denmark)); Lauritzen, Bent; Mikkelsen, Torben (Technical Univ. of Denmark, Risoe National Lab. for Sustainable Energy, Roskilde (Denmark))

    2008-07-15

    Within the NKS NordRisk project, 'Nuclear risk from atmospheric dispersion in Northern Europe', the NKS NordRisk Atlas has been developed. The atlas describes risks from hypothetical long-range atmospheric dispersion and deposition of radionuclides from selected nuclear risk sites in the Northern Hemisphere. A number of case studies of long-term long-range atmospheric transport and deposition of radionuclides has been developed, based on two years of meteorological data. Radionuclide concentrations in air and radionuclide depositions have been evaluated and examples of long-term averages of the dispersion and deposition and of the variability around these mean values are provided. (au)

  8. Geoinformation modeling system for analysis of atmosphere pollution impact on vegetable biosystems using space images

    Science.gov (United States)

    Polichtchouk, Yuri; Ryukhko, Viatcheslav; Tokareva, Olga; Alexeeva, Mary

    2002-02-01

    Geoinformation modeling system structure for assessment of the environmental impact of atmospheric pollution on forest- swamp ecosystems of West Siberia is considered. Complex approach to the assessment of man-caused impact based on the combination of sanitary-hygienic and landscape-geochemical approaches is reported. Methodical problems of analysis of atmosphere pollution impact on vegetable biosystems using geoinformation systems and remote sensing data are developed. Landscape structure of oil production territories in southern part of West Siberia are determined on base of processing of space images from spaceborn Resource-O. Particularities of atmosphere pollution zones modeling caused by gas burning in torches in territories of oil fields are considered. For instance, a pollution zones were revealed modeling of contaminants dispersal in atmosphere by standard model. Polluted landscapes areas are calculated depending on oil production volume. It is shown calculated data is well approximated by polynomial models.

  9. Report of the Nordic dispersion-/trajectory model comparison with the ETEX-1 fullscale experiment

    International Nuclear Information System (INIS)

    On the 6th and 7th June 1995 a meeting was held at Risoe, where calculations of the atmospheric transportation and dispersion of the ETEX-1 release carried out by a number of institutions in the Nordic countries were presented. Also presented were the results of the measurements carried out by the National Environmental Research Institute of Denmark, information previously not known to the participants in the meeting. This provided not only an opportunity of intercomparing the models, but also of carrying out a validation exercise. The main points form the concluding discussions are also included in this report. (au) 7 tabs., 75 ills

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

    Science.gov (United States)

    Sagan, C.

    1974-01-01

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

  11. Modelling the dispersion of particle numbers in five European cities

    NARCIS (Netherlands)

    Kukkonen, J.; Karl, M.; Keuken, M.P.; Denier van der Gon, H.A.C.; Denby, B.R.; Singh, V.; Douros, J.; Manders, A.M.M.; Samaras, Z.; Moussiopoulos, N.; Jonkers, S.; Aarnio, M.; Karppinen, A.; Kangas, L.; Lutzenkirchen, S.; Petaja, T.; Vouitsis, I.; Sokhi, R.S.

    2016-01-01

    We present an overview of the modelling of particle number concentrations (PNCs) in five major European cities, namely Helsinki, Oslo, London, Rotterdam and Athens in 2008. Novel emission inventories of particle numbers have been compiled both on urban and European scales. We used atmospheric disper

  12. Atmospheric corrosion: statistical validation of models

    International Nuclear Information System (INIS)

    In this paper we discuss two different methods for validation of regression models, applied to corrosion data. One of them is based on the correlation coefficient and the other one is the statistical test of lack of fit. Both methods are used here to analyse fitting of bi logarithmic model in order to predict corrosion for very low carbon steel substrates in rural and urban-industrial atmospheres in Uruguay. Results for parameters A and n of the bi logarithmic model are reported here. For this purpose, all repeated values were used instead of using average values as usual. Modelling is carried out using experimental data corresponding to steel substrates under the same initial meteorological conditions ( in fact, they are put in the rack at the same time). Results of correlation coefficient are compared with the lack of it tested at two different signification levels (α=0.01 and α=0.05). Unexpected differences between them are explained and finally, it is possible to conclude, at least in the studied atmospheres, that the bi logarithmic model does not fit properly the experimental data. (Author) 18 refs

  13. Study on the atmospheric dispersion of pollutant in the presence and absence of a hill for BARC, Trombay site

    International Nuclear Information System (INIS)

    Blocking effects generated by topographical features leads to complex flow patterns that might generate mean concentration distributions significantly different from those that might be expected from the mean flow in the absence of the complex terrain features for atmospheric releases of pollutants. The present paper deals with one such study of the effect of a hill on the atmospheric dispersion of pollutant for BARC, Trombay site. The study of wind flow as well as the atmospheric dispersion of pollutant in the presence of 130 m hill behind PP is found to be important to gauge the radiological consequences on population residing beyond this hill. The results of study of the effect of this hill on the wind flow and the concentration distribution of pollutants on the upwind and downwind side of the hill are presented in the paper. It is seen that the wind flow gets modified leading to deceleration in the upwind side of the hill due to terrain blocking, speed up at the top of the hill and deceleration behind the hill. In the absence of hill, flow remains uniform in the downwind direction. It is also found that in the presence of the hill, the released pollutant disperses more as compared to the absence of the hill. Because of the additional dispersion provided by the hill and also because of the elevated topography, the peak concentration value in the presence of hill is obtained at shorter distance when compared with the other case. The peak ground level concentration value found in the presence of hill is relatively higher; however, for the population residing at farther distances, the additional dilution provided by the hill reduces the ground level concentration. (author)

  14. Dispersion of sulphur in the northern hemisphere. A study with a 3-dimensional time-resolved model

    Energy Technology Data Exchange (ETDEWEB)

    Tarrason, L.

    1995-12-31

    This thesis on atmospheric dispersion of sulphur presents a calculation of intercontinental transport of oxidized sulphur and allocates different contributions to sulphur background levels over Europe. It is found that a significant fraction of anthropogenic sulphur (AS) is transported out of continental boundaries thus affecting the background levels over major parts of the northern hemisphere. Over Europe, the contribution of AS from North America is similar in amount to that of Asian AS and natural sources from the North Atlantic Ocean. Although the yearly contribution of intercontinental transport to deposition of sulphur over Europe is quite small, it can be much more important over certain areas and seasons and is comparable to the contributions from individual European countries. The calculations are based on a three-dimensional Eulerian time-resolved model that describes sulphur dispersion in the atmosphere in connection with large-scale synoptic flows and agree well with observations. The thesis emphasizes the role of synoptic scale atmospheric motions in determining intercontinental transport of sulphur. It indicates the need to resolve individual cyclones and anticyclones in order to describe the dispersion and distribution of atmospheric sulphur in the northern hemisphere and stresses the value of comparing model calculations with observations, both in atmospheric chemistry studies and in climate applications. 260 refs., 50 figs., 17 tabs.

  15. Recent Improvements to an Advanced Atmospheric Transport Modeling System

    Energy Technology Data Exchange (ETDEWEB)

    Buckley, R. L.; Hunter, C. H.

    2005-10-24

    The Atmospheric Technologies Group (ATG) has developed an advanced atmospheric modeling capability using the Regional Atmospheric Modeling System (RAMS) and a stochastic Lagrangian particle dispersion model (LPDM) for operational use at the Savannah River Site (SRS). For local simulations concerning releases from the Central Savannah River Area (CSRA), RAMS is run in a nested grid configuration with horizontal grid spacing of 8 and 2 km for each grid, with 6-hr forecasts updated every 3 hours. An interface to allow for easy user access to LPDM had been generated, complete with post-processing results depicting surface concentration, deposition, and a variety of dose quantities. A prior weakness in this approach was that observations from the SRS tower network were only incorporated into the three-dimensional modeling effort during the initialization process. Thus, if the forecasted wind fields were in error, the resulting plume predictions would also be erroneous. To overcome this shortcoming, the procedure for generating RAMS wind fields and reading them into LPDM has been modified such that SRS wind measurements are blended with the predicted three-dimensional wind fields from RAMS using the Barnes technique. In particular, the horizontal components in RAMS are replaced with the observed values at a series of 8 towers that exist within the SRS boundary (covering {approx}300 km{sup 2}). Even though LPDM is currently configured to account only for radioactive releases, it was used in a recent chlorine gas release to generate plume concentrations based on unit releases from the site of a train accident in Graniteville, South Carolina. This information was useful to local responders as an indication of potential protective actions downwind of the release.

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

    Science.gov (United States)

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

    2010-05-01

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

  17. FEM numerical model study of electrosurgical dispersive electrode design parameters.

    Science.gov (United States)

    Pearce, John A

    2015-08-01

    Electrosurgical dispersive electrodes must safely carry the surgical current in monopolar procedures, such as those used in cutting, coagulation and radio frequency ablation (RFA). Of these, RFA represents the most stringent design constraint since ablation currents are often more than 1 to 2 Arms (continuous) for several minutes depending on the size of the lesion desired and local heat transfer conditions at the applicator electrode. This stands in contrast to standard surgical activations, which are intermittent, and usually less than 1 Arms, but for several seconds at a time. Dispersive electrode temperature rise is also critically determined by the sub-surface skin anatomy, thicknesses of the subcutaneous and supra-muscular fat, etc. Currently, we lack fundamental engineering design criteria that provide an estimating framework for preliminary designs of these electrodes. The lack of a fundamental design framework means that a large number of experiments must be conducted in order to establish a reasonable design. Previously, an attempt to correlate maximum temperatures in experimental work with the average current density-time product failed to yield a good match. This paper develops and applies a new measure of an electrode stress parameter that correlates well with both the previous experimental data and with numerical models of other electrode shapes. The finite element method (FEM) model work was calibrated against experimental RF lesions in porcine skin to establish the fundamental principle underlying dispersive electrode performance. The results can be used in preliminary electrode design calculations, experiment series design and performance evaluation. PMID:26736814

  18. Atmospheric transmittance model for photosynthetically active radiation

    Energy Technology Data Exchange (ETDEWEB)

    Paulescu, Marius; Stefu, Nicoleta; Gravila, Paul; Paulescu, Eugenia; Boata, Remus; Pacurar, Angel; Mares, Oana [Physics Department, West University of Timisoara, V Parvan 4, 300223 Timisoara (Romania); Pop, Nicolina [Department of Physical Foundations of Engineering, Politehnica University of Timisoara, V Parvan 2, 300223 Timisoara (Romania); Calinoiu, Delia [Mechanical Engineering Faculty, Politehnica University of Timisoara, Mihai Viteazu 1, 300222 Timisoara (Romania)

    2013-11-13

    A parametric model of the atmospheric transmittance in the PAR band is presented. The model can be straightforwardly applied for calculating the beam, diffuse and global components of the PAR solar irradiance. The required inputs are: air pressure, ozone, water vapor and nitrogen dioxide column content, Ångström's turbidity coefficient and single scattering albedo. Comparison with other models and ground measured data shows a reasonable level of accuracy for this model, making it suitable for practical applications. From the computational point of view the calculus is condensed into simple algebra which is a noticeable advantage. For users interested in speed-intensive computation of the effective PAR solar irradiance, a PC program based on the parametric equations along with a user guide are available online at http://solar.physics.uvt.ro/srms.

  19. Physiologically Based Absorption Modeling for Amorphous Solid Dispersion Formulations.

    Science.gov (United States)

    Mitra, Amitava; Zhu, Wei; Kesisoglou, Filippos

    2016-09-01

    Amorphous solid dispersion (ASD) formulations are routinely used to enable the delivery of poorly soluble compounds. This type of formulations can enhance bioavailability due to higher kinetic solubility of the drug substance and increased dissolution rate of the formulation, by the virtue of the fact that the drug molecule exists in the formulation in a high energy amorphous state. In this article we report the application of physiologically based absorption models to mechanistically understand the clinical pharmacokinetics of solid dispersion formulations. Three case studies are shown here to cover a wide range of ASD bioperformance in human and modeling to retrospectively understand their in vivo behavior. Case study 1 is an example of fairly linear PK observed with dose escalation and the use of amorphous solubility to predict bioperformance. Case study 2 demonstrates the development of a model that was able to accurately predict the decrease in fraction absorbed (%Fa) with dose escalation thus demonstrating that such model can be used to predict the clinical bioperformance in the scenario where saturation of absorption is observed. Finally, case study 3 shows the development of an absorption model with the intent to describe the observed incomplete and low absorption in clinic with dose escalation. These case studies highlight the utility of physiologically based absorption modeling in gaining a thorough understanding of ASD performance and the critical factors impacting performance to drive design of a robust drug product that would deliver the optimal benefit to the patients. PMID:27442959

  20. MODELING OF GENERIC AIR POLLUTION DISPERSION ANALYSIS FROM CEMENT FACTORY

    Directory of Open Access Journals (Sweden)

    Moses E EMETERE

    2013-06-01

    Full Text Available Air pollution from cement factory is classified as one of the sources of air pollution. The control of the air pollution by addressing the wind field dynamics was the main objective of the paper. The dynamics of dispersion showed a three way flow which was calculated and explained accordingly. The 3D model showed good level of accuracy by determining field values of air deposited pollutants. Mean concentration of diffusing pollutants was shown to be directly proportional to the plume angular displacement. The 2D model explained the details of the wind field dynamics and proffers a solution which may be relevant in controlling air pollution from anthropogenic sources.

  1. An Empirical Model of Wage Dispersion with Sorting

    DEFF Research Database (Denmark)

    Bagger, Jesper; Lentz, Rasmus

    (submodular). The model is estimated on Danish matched employer-employee data. We find evidence of positive assortative matching. In the estimated equilibrium match distribution, the correlation between worker skill and firm productivity is 0.12. The assortative matching has a substantial impact on wage......This paper studies wage dispersion in an equilibrium on-the-job-search model with endogenous search intensity. Workers differ in their permanent skill level and firms differ with respect to productivity. Positive (negative) sorting results if the match production function is supermodular...

  2. A comparison of operational Lagrangian particle and adaptive puff models for plume dispersion forecasting

    Science.gov (United States)

    Souto, M. J.; Souto, J. A.; Pérez-Muñuzuri, V.; Casares, J. J.; Bermúdez, J. L.

    Transport and dispersion of pollutants in the lower atmosphere are predicted by using both a Lagrangian particle model (LPM) and an adaptive puff model (APM2) coupled to the same mesoscale meteorological prediction model PMETEO. LPM and APM2 apply the same numerical solutions for plume rise; but, for advection and plume growth, LPM uses a stochastic surrogate to the pollutant conservation equation, and APM2 applies interpolated winds and standard deviations from the meteorological model, using a step-wise Gaussian approach. The results of both models in forecasting the SO 2 ground level concentration (glc) around the 1400 MWe coal-fired As Pontes Power Plant are compared under unstable conditions. In addition, meteorological and SO 2 glc numerical results are compared to field measurements provided by 17 fully automated SO 2 glc remote stations, nine meteorological towers and one Remtech PA-3 SODAR, from a meteorological and air quality monitoring network located 30 km around the power plant.

  3. Modelling wet deposition in simulations of volcanic ash dispersion from hypothetical eruptions of Merapi, Indonesia

    Science.gov (United States)

    Dare, Richard A.; Potts, Rodney J.; Wain, Alan G.

    2016-10-01

    The statistical impact of including the process of wet deposition in dispersion model predictions of the movement of volcanic ash is assessed. Based on hypothetical eruptions of Merapi, Indonesia, sets of dispersion model simulations were generated, each containing four simulations per day over a period of three years, to provide results based on a wide range of atmospheric conditions. While on average dry sedimentation removes approximately 10% of the volcanic ash from the atmosphere during the first 24 h, wet deposition removes an additional 30% during seasons with highest rainfall (December and January) but only an additional 1% during August and September. The majority of the wet removal is due to in-cloud rather than below-cloud collection of volcanic ash particles. The largest uncertainties in the amount of volcanic ash removed by the process of wet deposition result from the choice of user-defined parameters used to compute the scavenging coefficient, and from the definition of the cloud top height. Errors in the precipitation field provided by the numerical weather prediction model utilised here have relatively less impact.

  4. Numerical modeling of atmospheric washout processes

    International Nuclear Information System (INIS)

    For the washout of particles from the atmosphere by clouds and rain one has to distinguish between processes which work in the first phase of cloud development, when condensation nuclei build up in saturated air (Nucleation Aerosol Scavenging, NAS) and those processes which work at the following cloud development. In the second case particles are taken off by cloud droplets or by falling rain drops via collision (Collision Aerosol Scavenging, CAS). The physics of both processes is described. For the CAS process a numerical model is presented. The report contains a documentation of the mathematical equations and the computer programs (FORTRAN). (KW)

  5. Spectral Analysis and Atmospheric Models of Microflares

    Institute of Scientific and Technical Information of China (English)

    Cheng Fang; Yu-Hua Tang; Zhi Xu

    2006-01-01

    By use of the high-resolution spectral data obtained with THEMIS on 2002 September 5, the spectra and characteristics of five well-observed microflares have been analyzed. Our results indicate that some of them are located near the longitudinal magnetic polarity inversion lines. All the microflares are accompanied by mass motions. The most obvious characteristic of the Hα microflare spectra is the emission at the center of both Hα and CaII 8542(A) lines. For the first time both thermal and non-thermal semi-empirical atmospheric models for the conspicuous and faint microflares are computed. In computing the non-thermal models, we assume that the electron beam resulting from magnetic reconnection is produced in the chromosphere, because it requires lower energies for the injected particles.It is found there is obvious heating in the low chromosphere. The temperature enhancement is about 1000-2200 K in the thermal models. If the non-thermal effects are included, then the required temperature increase can be reduced by 100-150 K. These imply that the Hα microflares can probably be produced by magnetic reconnection in the solar Iower atmosphere.The radiative and kinetic energies of the Hα microflares are estimated and the total energy is found to be 1027 - 4× 1028 erg.

  6. Conditions for the formation and atmospheric dispersion of a toxic, heavy gas layer during thermal metamorphism of coal and evaporite deposits by sill intrusion

    Science.gov (United States)

    Storey, Michael; Hankin, Robin K. S.

    2010-05-01

    There is compelling evidence for massive discharge of volatiles, including toxic species, into the atmosphere at the end of the Permian. It has been argued that most of the gases were produced during thermal metamorphism of coal and evaporite deposits in the East Siberia Tunguska basin following sill intrusion (Retallack and Jahren, 2008; Svensen et al., 2009). The release of the volatiles has been proposed as a major cause of environmental and extinction events at the end of the Permian, with venting of carbon gases and halocarbons to the atmosphere leading to global warming and atmospheric ozone depletion (Svensen et al., 2009) Here we consider the conditions required for the formation and dispersion of toxic, heavier than air, gas plumes, made up of a mixture of CO2, CH4, H2S and SO2 and formed during the thermal metamorphism of C- and S- rich sediments. Dispersion models and density considerations within a range of CO2/CH4 ratios and volatile fluxes and temperatures, for gas discharge by both seepage and from vents, allow the possibility that following sill emplacement much of the vast East Siberia Tunguska basin was - at least intermittently - covered by a heavy, toxic gas layer that was unfavorable for life. Dispersion scenarios for a heavy gas layer beyond the Siberian region during end-Permian times will be presented. REFERENCES G. J. Retallack and A. H. Jahren, Methane release from igneous intrusion of coal during Late Permian extinction events, Journal of Geology, volume 116, 1-20, 2008 H. Svensen et al., Siberian gas venting and the end-Permian environmental crisis, Earth and Planetary Science Letters, volume 277, 490-500, 2009

  7. A capture-recapture model of amphidromous fish dispersal

    Science.gov (United States)

    Smith, W.; Kwak, Thomas J.

    2014-01-01

    Adult movement scale was quantified for two tropical Caribbean diadromous fishes, bigmouth sleeper Gobiomorus dormitor and mountain mullet Agonostomus monticola, using passive integrated transponders (PITs) and radio-telemetry. Large numbers of fishes were tagged in Rio Mameyes, Puerto Rico, U.S.A., with PITs and monitored at three fixed locations over a 2-5 year period to estimate transition probabilities between upper and lower elevations and survival probabilities with a multistate Cormack-Jolly-Seber model. A sub-set of fishes were tagged with radio-transmitters and tracked at weekly intervals to estimate fine-scale dispersal. Changes in spatial and temporal distributions of tagged fishes indicated that neither G. dormitor nor A. monticola moved into the lowest, estuarine reaches of Rio Mameyes during two consecutive reproductive periods, thus demonstrating that both species follow an amphidromous, rather than catadromous, migratory strategy. Further, both species were relatively sedentary, with restricted linear ranges. While substantial dispersal of these species occurs at the larval stage during recruitment to fresh water, the results indicate minimal dispersal in spawning adults. Successful conservation of diadromous fauna on tropical islands requires management at both broad basin and localized spatial scales.

  8. Modeling flow around bluff bodies and predicting urban dispersion using large eddy simulation.

    Science.gov (United States)

    Tseng, Yu-Heng; Meneveau, Charles; Parlange, Marc B

    2006-04-15

    Modeling air pollutant transport and dispersion in urban environments is especially challenging due to complex ground topography. In this study, we describe a large eddy simulation (LES) tool including a new dynamic subgrid closure and boundary treatment to model urban dispersion problems. The numerical model is developed, validated, and extended to a realistic urban layout. In such applications fairly coarse grids must be used in which each building can be represented using relatively few grid-points only. By carrying out LES of flow around a square cylinder and of flow over surface-mounted cubes, the coarsest resolution required to resolve the bluff body's cross section while still producing meaningful results is established. Specifically, we perform grid refinement studies showing that at least 6-8 grid points across the bluff body are required for reasonable results. The performance of several subgrid models is also compared. Although effects of the subgrid models on the mean flow are found to be small, dynamic Lagrangian models give a physically more realistic subgrid-scale (SGS) viscosity field. When scale-dependence is taken into consideration, these models lead to more realistic resolved fluctuating velocities and spectra. These results set the minimum grid resolution and subgrid model requirements needed to apply LES in simulations of neutral atmospheric boundary layer flow and scalar transport over a realistic urban geometry. The results also illustrate the advantages of LES over traditional modeling approaches, particularly its ability to take into account the complex boundary details and the unsteady nature of atmospheric boundary layer flow. Thus LES can be used to evaluate probabilities of extreme events (such as probabilities of exceeding threshold pollutant concentrations). Some comments about computer resources required for LES are also included. PMID:16683605

  9. Model-based guidance and control for atmospheric guided entry

    OpenAIRE

    Canuto, Enrico; Ospina, Jose Alejandro

    2012-01-01

    This paper presents a solution of the translational control for a biconic atmospheric entry capsule using the bank angle as a command. The control algorithm is separated into path planning and reference-path tracking. The path-planning algorithm computes the entry trajectory from the navigated state at the Entry Interface Point until the desired Parachute Deployment Point. The algorithm aims to recover the landing site uncertainty caused by Entry Interface Point dispersions. Atmospheric and a...

  10. The NET effect of dispersants - a critical review of testing and modelling of surface oil dispersion

    NARCIS (Netherlands)

    Zeinstra-Helfrich, Marieke; Koops, Wierd; Murk, A.J.

    2015-01-01

    Application of chemical dispersants or mechanical dispersion on surface oil is a trade-off between surface effects (impact of floating oil) and sub-surface effects (impact of suspended oil). Making an informed decision regarding such response, requires insight in the induced change in fate and tr

  11. Uncertainty Quantification of RANS dispersion modeling in Oklahoma City during the Joint Urban 2003 campaign

    Science.gov (United States)

    Garcia-Sanchez, Clara; Gorle, Catherine; van Beeck, Jeroen; Iaccarino, Gianluca

    2014-11-01

    The high expansion rate of urban areas makes realistic predictions of dispersion within cities an important research topic. The transport of pollutants is influenced by wind flows that are affected by the large scale variability of the atmospheric boundary layer (ABL). In order to improve the predictive capabilities of Computational Fluid Dynamics simulations (CFD) of the ABL, this atmospheric variability should be included. This work focuses on representing this variability in the inflow boundary conditions using an uncertainty quantification framework for the Joint Urban 2003 experiment. The simulations focus on the Intensive Observation Period number 9, where a continuous release of SF6 took place in downtown Oklahoma. The RANS simulations with the k-epsilon turbulence model were performed with the code OpenFOAM, and an equation for passive scalar transport is solved, using a standard gradient diffusion model for the turbulent dispersion, to obtain the SF6 concentration. To define the inflow boundary conditions three uncertain parameters are used: wind speed, wind direction, and ABL roughness height. To propagate these uncertainties a tensor grid Clenshaw-Curtis Stochastic Collocation approach was used, and a polynomial chaos representation of the velocity and concentration at different field measurement locations was constructed to extract the mean and standard deviations.

  12. Xenon-133 and caesium-137 releases into the atmosphere from the Fukushima Dai-ichi nuclear power plant: determination of the source term, atmospheric dispersion, and deposition

    Directory of Open Access Journals (Sweden)

    A. Stohl

    2012-03-01

    Full Text Available On 11 March 2011, an earthquake occurred about 130 km off the Pacific coast of Japan's main island Honshu, followed by a large tsunami. The resulting loss of electric power at the Fukushima Dai-ichi nuclear power plant developed into a disaster causing massive release of radioactivity into the atmosphere. In this study, we determine the emissions into the atmosphere of two isotopes, the noble gas xenon-133 (133Xe and the aerosol-bound caesium-137 (137Cs, which have very different release characteristics as well as behavior in the atmosphere. To determine radionuclide emissions as a function of height and time until 20 April, we made a first guess of release rates based on fuel inventories and documented accident events at the site. This first guess was subsequently improved by inverse modeling, which combined it with the results of an atmospheric transport model, FLEXPART, and measurement data from several dozen stations in Japan, North America and other regions. We used both atmospheric activity concentration measurements as well as, for 137Cs, measurements of bulk deposition. Regarding 133Xe, we find a total release of 15.3 (uncertainty range 12.2–18.3 EBq, which is more than twice as high as the total release from Chernobyl and likely the largest radioactive noble gas release in history. The entire noble gas inventory of reactor units 1–3 was set free into the atmosphere between 11 and 15 March 2011. In fact, our release estimate is higher than the entire estimated 133Xe inventory of the Fukushima Dai-ichi nuclear power plant, which we explain with the decay of iodine-133 (half-life of 20.8 h into 133Xe. There is strong evidence that the 133Xe release started before the first active venting was made, possibly indicating structural damage to reactor components and/or leaks due to overpressure which would have allowed early release of noble gases. For 137

  13. Development of a comprehensive testing framework for Lagrangian dispersion models: Application to wet deposition in FLEXPART

    Science.gov (United States)

    Philipp, Anne; Seibert, Petra

    2015-04-01

    Tasks such as inverse modelling and prediction of transport and dispersion of aerosols and soluble gases are increasingly performed by Lagrangian particle models, e.g. FLEXPART (FLEXible PARTicle dispersion model, http://flexpart.eu). Applications include decision making in situations of crisis. Therefore, the credibility in their results should be established through extensive evaluation. Because of this, we are currently developing a testing environment for FLEXPART. This environment is not only going to test the functionality of the model as a whole but also the functionality of its components such as, for example, wet deposition. Test cases and corresponding evaluation already created by FLEXPART developers in the past shall be brought together in this single environment, allowing for efficient testing of future code additions and modifications. Regression testing is being applied, meaning that the collection of test cases for all parts of the model is used to make sure that a change in one part of the model does not negatively affect the behavior of all the other parts, including overall runtime. One component of FLEXPART is the deposition scheme. Because particulate or particle-borne trace substances undergo wet as well as dry deposition, it is an important part of atmospheric transport modelling and it is a major influence factor for the atmospheric lifetime of aerosols and soluble gases. Therefore, we are presenting the development of our testing environment based on the example of the implementation of an improved wet deposition scheme in the latest FLEXPART version. Besides the usual software tests for assessing the functionality, performance and the structure-oriented work flow of the code, we have to show that the physical results of the deposition fields are realistic. The component of the testing environment for a new wet deposition scheme implemented in FLEXPART should compare its results with (i) measured deposition data, (ii) results from previous

  14. User manual of nuclide dispersion in phreatic aquifers model

    International Nuclear Information System (INIS)

    The Nuclide Dispersion in Phreatic Aquifers (DRAF) model was developed in the 'Division Estudios Ambientales' of the 'Gerencia de Seguridad Radiologica y Nuclear, Comision Nacional de Energia Atomica' (1991), for the Safety Assessment of Near Surface Radioactive Waste Disposal Facilities. Afterwards, it was modified in several opportunities, adapting it to a number of application conditions. The 'Manual del usuario del codigo DRAF' here presented is a reference document for the use of the last three versions of the code developed for the 'Autoridad Regulatoria Nuclear' between 1995 and 1996. The DRAF model solves the three dimension's solute transport equation for porous media by the finite differences method. It takes into account the advection, dispersion, radioactive decay, and retention in the solid matrix processes, and has multiple possibilities for the source term. There are three versions of the model, two of them for the saturated zone and one for the unsaturated zone. All the versions have been verified in different conditions, and have been applied in exercises of the International Atomic Energy Agency and also in real cases. (author)

  15. The Lagrangian particle dispersion model FLEXPART-WRF version 3.1

    Science.gov (United States)

    Brioude, J.; Arnold, D.; Stohl, A.; Cassiani, M.; Morton, D.; Seibert, P.; Angevine, W.; Evan, S.; Dingwell, A.; Fast, J. D.; Easter, R. C.; Pisso, I.; Burkhart, J.; Wotawa, G.

    2013-11-01

    The Lagrangian particle dispersion model FLEXPART was originally designed for calculating long-range and mesoscale dispersion of air pollutants from point sources, such that occurring after an accident in a nuclear power plant. In the meantime, FLEXPART has evolved into a comprehensive tool for atmospheric transport modeling and analysis at different scales. A need for further multiscale modeling and analysis has encouraged new developments in FLEXPART. In this paper, we present a FLEXPART version that works with the Weather Research and Forecasting (WRF) mesoscale meteorological model. We explain how to run this new model and present special options and features that differ from those of the preceding versions. For instance, a novel turbulence scheme for the convective boundary layer has been included that considers both the skewness of turbulence in the vertical velocity as well as the vertical gradient in the air density. To our knowledge, FLEXPART is the first model for which such a scheme has been developed. On a more technical level, FLEXPART-WRF now offers effective parallelization, and details on computational performance are presented here. FLEXPART-WRF output can either be in binary or Network Common Data Form (NetCDF) format, both of which have efficient data compression. In addition, test case data and the source code are provided to the reader as a Supplement. This material and future developments will be accessible at http://www.flexpart.eu.

  16. Leakage and atmospheric dispersion of CO2 associated with carbon capture and storage projects

    OpenAIRE

    Mazzoldi, Alberto

    2009-01-01

    Climate change is affecting planet Earth. The main cause is anthropogenic emissions of greenhouse gases, the principal one being carbon dioxide, released in the atmosphere as a by-product of the combustion of hydrocarbons for the generation of energy. Carbon capture and storage (CCS) is a technology that would prevent carbon dioxide from being emitted into the atmosphere by safely sequestering it underground. For so doing, CO2 must be captured at large emission points and transported at high ...

  17. Modeling of dilute and dense dispersed fluid-particle flow

    Energy Technology Data Exchange (ETDEWEB)

    Laux, Harald

    1998-08-01

    A general two-fluid model is derived and applied in CFD computations to various test cases of important industrial multiphase flows. It is general in the sense of its applicability to dilute and dense dispersed fluid-particle flows. The model is limited to isothermal flow without mass transfer and only one particle phase is described. The instantaneous fluid phase equations, including the phase interaction terms, are derived from a volume averaging technique, and the instantaneous particle phase equations are derived from the kinetic theory of granular material. Whereas the averaging procedure, the treatment of the interaction terms, and the kinetic theory approach have been reported in literature prior to this work the combination of the approaches is new. The resulting equations are derived without ambiguity in the interpretation of the particle phase pressure (equation-of-state of particle phase). The basic modeling for the particle phase is improved in two steps. Because in the basic modeling only stresses due to kinetic and collisional interactions are included, a simple model for an effective viscosity is developed in order to allow also frictional stresses within the particle phase. Moreover, turbulent stresses and turbulent dispersion of particles play often an important role for the transport processes. Therefore in a second step, a two-equation turbulence model for both fluid and particle phase turbulence is derived by applying the phasic average to the instantaneous equations. The resulting k-{epsilon}-k{sup d}-{epsilon}{sup d} model is new. Mathematical closure is attempted such that the resulting set of equations is valid for both dilute arid dense flows. During the development of the closure relations a clear distinction is made between granular or ''viscous'' microscale fluctuations and turbulent macro scale fluctuations (true particle turbulence) within the particle phase. The set of governing equations is discretized by using a

  18. Comparison of Average Transport and Dispersion Among a Gaussian Model, a Two-Dimensional Model and a Three-Dimensional Model

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, J A; Molenkamp, C R; Bixler, N E; Morrow, C W; Ramsdell, Jr., J V

    2004-05-10

    The Nuclear Regulatory Commission uses MACCS2 (MELCOR Accident Consequence Code System, Version 2) for regulatory purposes such as planning for emergencies and cost-benefit analyses. MACCS2 uses a straight-line Gaussian model for atmospheric transport and dispersion. This model has been criticized as being overly simplistic, although only expected values of metrics of interest are used in the regulatory arena. To test the assumption that averaging numerous weather results adequately compensates for the loss of structure in the meteorology that occurs away from the point of release, average MACCS2 results have been compared with average results from a state-of-the-art, 3-dimensional LODI (Lagrangian Operational Dispersion Integrator)/ADAPT (Atmospheric Data Assimilation and Parameterization Technique) and a Lagrangian trajectory, Gaussian puff transport and dispersion model from RASCAL (Radiological Assessment System for consequence Analysis). The weather sample included 610 weather trials representing conditions for a hypothetical release at the Central Facility of the Department of Energy's Atmospheric Radiation Measurement site. The values compared were average ground concentrations and average surface-level air concentrations at several distances out to 100 miles (160.9 km) from the assumed release site.

  19. Factors influencing separation distances against odour annoyance calculated by Gaussian and Lagrangian dispersion models

    Science.gov (United States)

    Piringer, Martin; Knauder, Werner; Petz, Erwin; Schauberger, Günther

    2016-09-01

    Direction-dependent separation distances to avoid odour annoyance, calculated with the Gaussian Austrian Odour Dispersion Model AODM and the Lagrangian particle diffusion model LASAT at two sites, are analysed and compared. The relevant short-term peak odour concentrations are calculated with a stability-dependent peak-to-mean algorithm. The same emission and meteorological data, but model-specific atmospheric stability classes are used. The estimate of atmospheric stability is obtained from three-axis ultrasonic anemometers using the standard deviations of the three wind components and the Obukhov stability parameter. The results are demonstrated for the Austrian villages Reidling and Weissbach with very different topographical surroundings and meteorological conditions. Both the differences in the wind and stability regimes as well as the decrease of the peak-to-mean factors with distance lead to deviations in the separation distances between the two sites. The Lagrangian model, due to its model physics, generally calculates larger separation distances. For worst-case calculations necessary with environmental impact assessment studies, the use of a Lagrangian model is therefore to be preferred over that of a Gaussian model. The study and findings relate to the Austrian odour impact criteria.

  20. Modeling Responses of Leafy Spurge Dispersal to Control Strategies

    Institute of Scientific and Technical Information of China (English)

    Zewei Miao

    2007-01-01

    Leafy spurge (Euphorbia esula L.) has substantial negative effects on grassland biodiversity, productivity, and economic benefit in North America.To predict these negative impacts, we need an appropriate plant-spread model which can simulate the response of an invading population to different control strategies.In this study, using a stochastic map lattice approach we generated a spatially explicitly stochastic process-based model to simulate dispersal trajectories of leafy spurge under various control scenarios.The model integrated dispersal curve, propagule pressure, and population growth of leafy spurge at local and short-temporal scales to capture spread features of leafy spurge at large spatial and long-temporal scales.Our results suggested that narrow-, medium-, and fat-tailed kernels did not differ In their ability to predict spread, in contrast to previous works.For all kernels, Allee effects were significantly present and could explain the lag phase (three decades)before leafy spurge spread accelerated.When simulating from the initial stage of introduction, Allee effects were critical in predicting spread rate of leafy spurge, because the prediction could be seriously affected by the low density period of leafy spurge community.No Allee effects models were not able to simulate spread rate well in this circumstance.When applying control strategies to the current diatribution, Allee effects could stop the spread of leafy spurge; no Allee effects models, however, were able to slow but not stop the spread.The presence of Allee effects had significant ramifications on the efficiencies of control strategies.For both Allee and no Allee effects models, the later that control strategies were implemented, the more effort had to be input to achieve similar control results.

  1. Essays on pricing dynamics, price dispersion, and nested logit modelling

    Science.gov (United States)

    Verlinda, Jeremy Alan

    The body of this dissertation comprises three standalone essays, presented in three respective chapters. Chapter One explores the possibility that local market power contributes to the asymmetric relationship observed between wholesale costs and retail prices in gasoline markets. I exploit an original data set of weekly gas station prices in Southern California from September 2002 to May 2003, and take advantage of highly detailed station and local market-level characteristics to determine the extent to which spatial differentiation influences price-response asymmetry. I find that brand identity, proximity to rival stations, bundling and advertising, operation type, and local market features and demographics each influence a station's predicted asymmetric relationship between prices and wholesale costs. Chapter Two extends the existing literature on the effect of market structure on price dispersion in airline fares by modeling the effect at the disaggregate ticket level. Whereas past studies rely on aggregate measures of price dispersion such as the Gini coefficient or the standard deviation of fares, this paper estimates the entire empirical distribution of airline fares and documents how the shape of the distribution is determined by market structure. Specifically, I find that monopoly markets favor a wider distribution of fares with more mass in the tails while duopoly and competitive markets exhibit a tighter fare distribution. These findings indicate that the dispersion of airline fares may result from the efforts of airlines to practice second-degree price discrimination. Chapter Three adopts a Bayesian approach to the problem of tree structure specification in nested logit modelling, which requires a heavy computational burden in calculating marginal likelihoods. I compare two different techniques for estimating marginal likelihoods: (1) the Laplace approximation, and (2) reversible jump MCMC. I apply the techniques to both a simulated and a travel mode

  2. Disclosure of the National Data Centre Preparedness Exercise 2013 radionuclide release and atmospheric dispersion scenario

    Science.gov (United States)

    Ross, J. Ole; Hartmann, Gernot; Ceranna, Lars; Gestermann, Nicolai

    2015-04-01

    justified. Various pieces of Supplementary Information were offered in order to facilitate a broad participation of NDCs. Finally, the full NPE2013 scenario was disclosed at the NDC Workshop in Vienna in May 2014. The radionuclide source scenario and location as well as the forward Atmospheric Transport Modelling (ATM) to generate the simulated concentrations are presented. The specific challenges of the localization of the fictitious radionuclide source by means of ATM backtracking and isotopic composition analysis are pointed out. The underlying scenario of NPE2013 was a false-positive: The induced seismic event in FRISIA was completely unrelated to the simulated reactor release at 600 km distance in a neighbouring country. The NPE2013 addressed thus a number of relevant issues which have to be considered when dealing with data of the International Monitoring System and of additional national technical means in the pre-run of a request for an On-Site Inspection.

  3. Study on Dispersion Properties of Photonic Crystal Fiber by Effective-Index Model

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The group-velocity-dispersion properties of photonic crystal fiber (PCF) were investigated by effective-index model. The relationship between waveguide dispersion and structure parameters: the pitch A and the relative hole size/was studied.

  4. Modeling distribution of dispersal distances in male white-tailed deer

    Science.gov (United States)

    Diefenbach, D.R.; Long, E.S.; Rosenberry, C.S.; Wallingford, B.D.; Smith, D.R.

    2008-01-01

    Dispersal distances and their distribution pattern are important to understanding such phenomena as disease spread and gene flow, but oftentimes dispersal characteristics are modeled as a fixed trait for a given species. We found that dispersal distributions differ for spring and autumn dispersals of yearling male white-tailed deer (Odocoileus virginianus) but that combined data can be adequately modeled based on a log-normal distribution. We modeled distribution of dispersal distances from 3 distinct populations in Pennsylvania and Maryland, USA, based on the relationship between percent forest cover and mean dispersal distance and the relationship between mean and variance of dispersal distances. Our results suggest distributions of distances for dispersing yearling male white-tailed deer can be modeled by simply measuring a readily obtained landscape metric, percent forest cover, which could be used to create generalized spatially explicit disease or gene.

  5. Critical review of hydraulic modeling on atmospheric heat dissipation

    International Nuclear Information System (INIS)

    Objectives of this study were: to define the useful roles of hydraulic modeling in understanding the predicting atmospheric effects of heat dissipation systems; to assess the state-of-the-art of hydraulic modeling of atmospheric phenomena; to inventory potentially useful existing hydraulic modeling facilities both in the United States and abroad; and to scope hydraulic model studies to assist the assessment of atmospheric effects of nuclear energy centers

  6. The Lagrangian particle dispersion model FLEXPART-WRF version 3.0

    Science.gov (United States)

    Brioude, J.; Arnold, D.; Stohl, A.; Cassiani, M.; Morton, D.; Seibert, P.; Angevine, W.; Evan, S.; Dingwell, A.; Fast, J. D.; Easter, R. C.; Pisso, I.; Burkhart, J.; Wotawa, G.

    2013-07-01

    The Lagrangian particle dispersion model FLEXPART was originally designed for calculating long-range and mesoscale dispersion of air pollutants from point sources, such as after an accident in a nuclear power plant. In the meantime FLEXPART has evolved into a comprehensive tool for atmospheric transport modeling and analysis at different scales. This multiscale need has encouraged new developments in FLEXPART. In this document, we present a FLEXPART version that works with the Weather Research and Forecasting (WRF) mesoscale meteorological model. We explain how to run and present special options and features that differ from its predecessor versions. For instance, a novel turbulence scheme for the convective boundary layer has been included that considers both the skewness of turbulence in the vertical velocity as well as the vertical gradient in the air density. To our knowledge, FLEXPART is the first model for which such a scheme has been developed. On a more technical level, FLEXPART-WRF now offers effective parallelization and details on computational performance are presented here. FLEXPART-WRF output can either be in binary or Network Common Data Form (NetCDF) format with efficient data compression. In addition, test case data and the source code are provided to the reader as Supplement. This material and future developments will be accessible at http://www.flexpart.eu.

  7. The Lagrangian particle dispersion model FLEXPART-WRF version 3.0

    Directory of Open Access Journals (Sweden)

    J. Brioude

    2013-07-01

    Full Text Available The Lagrangian particle dispersion model FLEXPART was originally designed for calculating long-range and mesoscale dispersion of air pollutants from point sources, such as after an accident in a nuclear power plant. In the meantime FLEXPART has evolved into a comprehensive tool for atmospheric transport modeling and analysis at different scales. This multiscale need has encouraged new developments in FLEXPART. In this document, we present a FLEXPART version that works with the Weather Research and Forecasting (WRF mesoscale meteorological model. We explain how to run and present special options and features that differ from its predecessor versions. For instance, a novel turbulence scheme for the convective boundary layer has been included that considers both the skewness of turbulence in the vertical velocity as well as the vertical gradient in the air density. To our knowledge, FLEXPART is the first model for which such a scheme has been developed. On a more technical level, FLEXPART-WRF now offers effective parallelization and details on computational performance are presented here. FLEXPART-WRF output can either be in binary or Network Common Data Form (NetCDF format with efficient data compression. In addition, test case data and the source code are provided to the reader as Supplement. This material and future developments will be accessible at http://www.flexpart.eu.

  8. Simulating Flow and Dispersion by Using WRF-CFD Coupled Model in a Built-Up Area of Shenyang, China

    Directory of Open Access Journals (Sweden)

    Yijia Zheng

    2015-01-01

    Full Text Available Results are presented from a series of numerical studies designed to investigate the atmospheric boundary layer structure, ambient wind, and pollutant source location and their impacts on the wind field and pollutant distribution within the built-up areas of Shenyang, China. Two models, namely, Open Source Field Operation and Manipulation (OpenFOAM software package and Weather Research and Forecasting (WRF model, are used in the present study. Then the high resolution computational fluid dynamics (CFD numerical experiments were performed under the typical simulated atmospheric boundary conditions. It was found that the atmospheric boundary structure played a crucial role in the pollution within the building cluster, which determined the potential turbulent diffusion ability of the atmospheric surface layer; the change of the ambient wind direction can significantly affect the dispersion pattern of pollutants, which was a more sensitive factor than the ambient wind speed; under a given atmospheric state, the location of the pollution sources would dramatically determine the pollution patterns within built-up areas. The WRF-CFD numerical evaluation is a reliable method to understand the complicated flow and dispersion within built-up areas.

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

    Science.gov (United States)

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

    2013-12-01

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

  10. Improving the low temperature dyeability of polyethylene terephthalate fabric with dispersive dyes by atmospheric pressure plasma discharge

    Science.gov (United States)

    Elabid, Amel E. A.; Zhang, Jie; Shi, Jianjun; Guo, Ying; Ding, Ke; Zhang, Jing

    2016-07-01

    Polyethylene terephthalate (PET) fiber and textile is one of the largest synthetic polymer commodity in the world. The great energy consumption and pollution caused by the high temperature and pressure dyeing of PET fibers and fabrics with disperse dyes has been caused concern these years. In this study, an atmospheric pressure plasma with fine and uniform filament discharge operated at 20 kHz has been used to improve the low temperature dyeability of PET fabric at 95 °C with three cation disperse dyes: Red 73, Blue 183 and Yellow 211. The dyes uptake percentage of the treated PET fabrics was observed to increase as twice as much of untreated fabric. The color strength rate was increased more than 20%. The reducing of the water contact angle and the raising of the capillary height of treated PET fabric strip indicate its hydrophilicity improvement. Scanning electron microscope (SEM) results display nano to micro size of etching pits appeared uniformly on the fiber surface of the treated PET. Simultaneously, X-ray photoelectron spectroscopy (XPS) analysis indicates an increase of the oxygen content in the surface caused by the introduction of polar groups such as Cdbnd O and COOH. The rough surface with improved polar oxygen groups showed hydrophilicity and affinity to C.I. dispersive dyes and is believed to be caused by the strong and very fine filament discharge appearing randomly at one place at an instant but evenly at many places at a longer period. This increases the diffusion and absorption of the C.I. disperse dyes on the PET fiber surface, which improve its low temperature dyeability.

  11. Dispersion model for airborne particulates inside a building

    International Nuclear Information System (INIS)

    An empirical model has been developed for the spread of airborne radioactive particles after they are released inside a building. The model has been useful in performing safety analyses of actinide materials facilities at the Savannah River Plant (SRP). These facilities employ the multiple-air-zone concept; that is, ventilation air flows from rooms or areas of least radioactive material hazard, through zones of increasing hazard, to a treatment system. A composite of the data for dispersion of airborne activity during 12 actual case incidents at SRP forms the basis for this model. These incidents occurred during approximately 90 plant-years of experience at SRP with the chemical and metallurgical processing of purified neptunium and plutonium after their recovery from irradiated uranium. The model gives ratios of the airborne activity concentrations in rooms and corridors near the site of the release. The multiple-air-zone concept has been applied to many designs of nuclear facilities as a safety feature to limit the spread of airborne activity from a release. The model illustrates the limitations of this concept: it predicts an apparently anomalous behavior of airborne particulates; namely, a small migration against the flow of the ventilation air

  12. Study on fitness functions of genetic algorithm for dynamically correcting nuclide atmospheric diffusion model

    International Nuclear Information System (INIS)

    Background: In radioactive nuclides atmospheric diffusion models, the empirical dispersion coefficients were deduced under certain experiment conditions, whose difference with nuclear accident conditions is a source of deviation. A better estimation of the radioactive nuclide's actual dispersion process could be done by correcting dispersion coefficients with observation data, and Genetic Algorithm (GA) is an appropriate method for this correction procedure. Purpose: This study is to analyze the fitness functions' influence on the correction procedure and the forecast ability of diffusion model. Methods: GA, coupled with Lagrange dispersion model, was used in a numerical simulation to compare 4 fitness functions' impact on the correction result. Results: In the numerical simulation, the fitness function with observation deviation taken into consideration stands out when significant deviation exists in the observed data. After performing the correction procedure on the Kincaid experiment data, a significant boost was observed in the diffusion model's forecast ability. Conclusion: As the result shows, in order to improve dispersion models' forecast ability using GA, observation data should be given different weight in the fitness function corresponding to their error. (authors)

  13. Instantaneous and time-averaged dispersion and measurement models for estimation theory applications with elevated point source plumes

    Science.gov (United States)

    Diamante, J. M.; Englar, T. S., Jr.; Jazwinski, A. H.

    1977-01-01

    Estimation theory, which originated in guidance and control research, is applied to the analysis of air quality measurements and atmospheric dispersion models to provide reliable area-wide air quality estimates. A method for low dimensional modeling (in terms of the estimation state vector) of the instantaneous and time-average pollutant distributions is discussed. In particular, the fluctuating plume model of Gifford (1959) is extended to provide an expression for the instantaneous concentration due to an elevated point source. Individual models are also developed for all parameters in the instantaneous and the time-average plume equations, including the stochastic properties of the instantaneous fluctuating plume.

  14. An Axial Dispersion Model for Evaporating Bubble Column Reactor

    Institute of Scientific and Technical Information of China (English)

    谢刚; 李希

    2004-01-01

    Evaporating bubble column reactor (EBCR) is a kind of aerated reactor in which the reaction heat is removed by the evaporation of volatile reaction mixture. In this paper, a mathematical model that accounts for the gas-liquid exothermic reaction and axial dispersions of both gas and liquid phase is employed to study the performance of EBCR for the process of p-xylene(PX) oxidation. The computational results show that there are remarkable concentration and temperature gradients in EBCR for high ratio of height to diameter (H/DT). The temperature is lower at the bottom of column and higher at the top, due to rapid evaporation induced by the feed gas near the bottom. The concentration profiles in the gas phase are more nonuniform than those (except PX) in the liquid phase, which causes more solvent burning consumption at high H/DT ratio. For p-xylene oxidation, theo ptimal H/DT is around 5.

  15. Fish dispersal in fragmented landscapes: a modeling framework for quantifying the permeability of structural barriers.

    Science.gov (United States)

    Pépino, Marc; Rodríguez, Marco A; Magnan, Pierre

    2012-07-01

    Dispersal is a key determinant of the spatial distribution and abundance of populations, but human-made fragmentation can create barriers that hinder dispersal and reduce population viability. This study presents a modeling framework based on dispersal kernels (modified Laplace distributions) that describe stream fish dispersal in the presence of obstacles to passage. We used mark-recapture trials to quantify summer dispersal of brook trout (Salvelinus fontinalis) in four streams crossed by a highway. The analysis identified population heterogeneity in dispersal behavior, as revealed by the presence of a dominant sedentary component (48-72% of all individuals) characterized by short mean dispersal distance (dispersal distance (56-1086 m). We did not detect evidence of barrier effects on dispersal through highway crossings. Simulation of various plausible scenarios indicated that detectability of barrier effects was strongly dependent on features of sampling design, such as spatial configuration of the sampling area, barrier extent, and sample size. The proposed modeling framework extends conventional dispersal kernels by incorporating structural barriers. A major strength of the approach is that ecological process (dispersal model) and sampling design (observation model) are incorporated simultaneously into the analysis. This feature can facilitate the use of prior knowledge to improve sampling efficiency of mark-recapture trials in movement studies. Model-based estimation of barrier permeability and its associated uncertainty provides a rigorous approach for quantifying the effect of barriers on stream fish dispersal and assessing population dynamics of stream fish in fragmented landscapes.

  16. Measurement and modelling of tritium dispersion in vicinity of nuclear fusion facilities

    International Nuclear Information System (INIS)

    To construct and validate models for the assessment of the impact of tritium gas releases from future nuclear fusion facilities, it is essential to investigate the fate of tritium gas after release to the environment. JAERI's experimental results of a tritium gas (HT) field release experiment and modelling of environmental tritium dispersion in the vicinity of facilities are described in this paper. In the HT gas field release experiment, air, soil and pine needle samples were collected for analysis during the extended period of 5 days after the HT release. Efforts were directed toward quantifying: direct oxidation rate of HT to HTO in the atmosphere; rate of appearance of atmospheric HTO from a release of HT; deposition velocities of HT and HTO to soil; loss rate of HTO from soil; deposition velocity of HTO to pine needles; diffusion coefficient and oxidation rate constant of HT gas in soil. A model for cycling of tritium in the environment near fusion facilities was developed considering possible items relating to tritium behavior. And it was applied to the experimental data to determine diffusion coefficients and oxidation rate constants of HT in soil. These parameter values and the model were used for prediction of environmental tritium concentrations. (author)

  17. Lithospheric Thickness Modeled from Long Period Surface Wave Dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Pasyanos, M E

    2008-05-15

    The behavior of surface waves at long periods is indicative of subcrustal velocity structure. Using recently published dispersion models, we invert surface wave group velocities for lithospheric structure, including lithospheric thickness, over much of the Eastern Hemisphere, encompassing Eurasia, Africa, and the Indian Ocean. Thicker lithosphere under Precambrian shields and platforms are clearly observed, not only under the large cratons (West Africa, Congo, Baltic, Russia, Siberia, India), but also under smaller blocks like the Tarim Basin and Yangtze craton. In contrast, it is found that remobilized Precambrian structures like the Saharan Shield and Sino-Korean Paraplatform do not have well-established lithospheric keels. The thinnest lithospheric thickness is found under oceanic and continental rifts, as well as along convergence zones. We compare our results to thermal models of continental lithosphere, lithospheric cooling models of oceanic lithosphere, lithosphere-asthenosphere boundary (LAB) estimates from S-wave receiver functions, and velocity variations of global tomography models. In addition to comparing results for the broad region, we examine in detail the regions of Central Africa, Siberia, and Tibet. While there are clear differences in the various estimates, overall the results are generally consistent. Inconsistencies between the estimates may be due to a variety of reasons including lateral and depth resolution differences and the comparison of what may be different lithospheric features.

  18. A CFD model for pollutant dispersion in rivers

    Directory of Open Access Journals (Sweden)

    Modenesi K.

    2004-01-01

    Full Text Available Studies have shown that humankind will experience a water shortage in the coming decades. It is therefore paramount to develop new techniques and models with a view to minimizing the impact of pollution. It is important to predict the environmental impact of new emissions in rivers, especially during periods of drought. Computational fluid dynamics (CFD has proved to be an invaluable tool to develop models able to analyze in detail particle dispersion in rivers. However, since these models generate grids with thousands (even millions of points to evaluate velocities and concentrations, they still require powerful machines. In this context, this work contributes by presenting a new three-dimensional model based on CFD techniques specifically developed to be fast, providing a significant improvement in performance. It is able to generate predictions in a couple of hours for a one-thousand-meter long section of river using Pentium IV computers. Commercial CFD packages would require weeks to solve the same problem. Another innovation inb this work is that a half channel with a constant elliptical cross section represents the river, so the Navier Stokes equations were derived for the elliptical system. Experimental data were obtained from REPLAN (PETROBRAS refining unit on the Atibaia River in São Paulo, Brazil. The results show good agreement with experimental data.

  19. TSUNAMI PROPAGATION OVER THE NORTH PACIFIC: DISPERSIVE AND NONDISPERSIVE MODELS

    Directory of Open Access Journals (Sweden)

    Juan Horrillo

    2012-01-01

    Full Text Available Hydrostatic (HY and non-hydrostatic (NHY tsunami physics is compared by application to the Kuril Island Tsunami (KIT of November 2006 and the Japan Tsunami (JT of March 2011. Our purpose is to study the significance of dispersive vs. non-dispersive long waves on global tsunami propagation. A tool which is well suited to revealing tsunami wave transformations is the energy flux. Expressions for dispersive and non-dispersive fluxes have been formulated. This provides an understanding of the role of dispersion in tsunami propagation and dissipation. Separating the pressure field into two parts i.e., HY and NHY shows that dispersive waves extract energy from the main wave, directing the dispersive energy flux away from the wave front. The major result of the application of the energy flux to non-dispersive waves is an enhanced understanding of later tsunami wave train arrivals at distant points – with arrivals sometimes occurring several hours after an initial forerunner wave. Computations show that strong differences between non-dispersive and dispersive waves develop along the length of the main energy beam. This has important consequences for accurate tsunami prediction and warnings.

  20. On classical meteor light curves and utilitarian model atmospheres

    Science.gov (United States)

    Beech, M.; Hargrove, M.

    2005-01-01

    We present a series of classical meteor light curve profiles based upon a set of simplified analytic atmospheric models. The model atmospheres specifically express the density variation as a power law in atmospheric height, and are derived under a variety of assumptions relating to the atmospheric temperature profile and the variation of the acceleration due to gravity. We find that the light curve profiles show only small differences with respect to any variation in the temperature profile and the geometry imposed upon the atmospheres.

  1. Evaluating atmospheric methane inversion model results for Pallas, northern Finland

    NARCIS (Netherlands)

    Tsuruta, Aki; Aalto, Tuula; Backman, Leif; Peters, Wouter; Krol, Maarten; van der Laan-Luijkx, Ingrid T.; Hatakka, Juha; Heikkinen, Pauli; Dlugokencky, Edward J.; Spahni, Renato; Paramonova, Nina N.

    2015-01-01

    A state-of-the-art inverse model, CarbonTracker Data Assimilation Shell (CTDAS), was used to optimize estimates of methane (CH4) surface fluxes using atmospheric observations of CH4 as a constraint. The model consists of the latest version of the TM5 atmospheric chemistry-transport model and an ense

  2. Inverse estimation of source parameters of oceanic radioactivity dispersion models associated with the Fukushima accident

    Directory of Open Access Journals (Sweden)

    Y. Miyazawa

    2013-04-01

    Full Text Available With combined use of the ocean–atmosphere simulation models and field observation data, we evaluate the parameters associated with the total caesium-137 amounts of the direct release into the ocean and atmospheric deposition over the western North Pacific caused by the accident of Fukushima Daiichi nuclear power plant (FNPP that occurred in March 2011. The Green's function approach is adopted for the estimation of two parameters determining the total emission amounts for the period from 12 March to 6 May 2011. It is confirmed that the validity of the estimation depends on the simulation skill near FNPP. The total amount of the direct release is estimated as 5.5–5.9 × 1015 Bq, while that of the atmospheric deposition is estimated as 5.5–9.7 × 1015 Bq, which indicates broader range of the estimate than that of the direct release owing to uncertainty of the dispersion widely spread over the western North Pacific.

  3. Inverse estimation of source parameters of oceanic radioactivity dispersion models associated with the Fukushima accident

    Directory of Open Access Journals (Sweden)

    Y. Miyazawa

    2012-10-01

    Full Text Available With combined use of the ocean-atmosphere simulation models and field observation data, we evaluate the parameters associated with the total caesium-137 amounts of the direct release into the ocean and atmospheric deposition over the Western North Pacific caused by the accident of Fukushima Daiichi nuclear power plant (FNPP that occurred in March 2011. The Green's function approach is adopted for the estimation of two parameters determining the total emission amounts for the period from 12 March to 6 May 2011. It is confirmed that the validity of the estimation depends on the simulation skill near FNPP. The total amount of the direct release is estimated as 5.5–5.9 × 1015 Bq, while that of the atmospheric deposition is estimated as 5.5–9.7 × 1015 Bq, which indicates broader range of the estimate than that of the direct release owing to uncertainty of the dispersion widely spread over the Western North Pacific.

  4. Atmospheric Modeling And Sensor Simulation (AMASS) study

    Science.gov (United States)

    Parker, K. G.

    1985-01-01

    A 4800 band synchronous communications link was established between the Perkin-Elmer (P-E) 3250 Atmospheric Modeling and Sensor Simulation (AMASS) system and the Cyber 205 located at the Goddard Space Flight Center. An extension study of off-the-shelf array processors offering standard interface to the Perkin-Elmer was conducted to determine which would meet computational requirements of the division. A Floating Point Systems AP-120B was borrowed from another Marshall Space Flight Center laboratory for evaluation. It was determined that available array processors did not offer significantly more capabilities than the borrowed unit, although at least three other vendors indicated that standard Perkin-Elmer interfaces would be marketed in the future. Therefore, the recommendation was made to continue to utilize the 120B ad to keep monitoring the AP market. Hardware necessary to support requirements of the ASD as well as to enhance system performance was specified and procured. Filters were implemented on the Harris/McIDAS system including two-dimensional lowpass, gradient, Laplacian, and bicubic interpolation routines.

  5. Using data from an encounter sampler to model fish dispersal

    Science.gov (United States)

    Obaza, A.; DeAngelis, D.L.; Trexler, J.C.

    2011-01-01

    A method to estimate speed of free-ranging fishes using a passive sampling device is described and illustrated with data from the Everglades, U.S.A. Catch per unit effort (CPUE) from minnow traps embedded in drift fences was treated as an encounter rate and used to estimate speed, when combined with an independent estimate of density obtained by use of throw traps that enclose 1 m2 of marsh habitat. Underwater video was used to evaluate capture efficiency and species-specific bias of minnow traps and two sampling studies were used to estimate trap saturation and diel-movement patterns; these results were used to optimize sampling and derive correction factors to adjust species-specific encounter rates for bias and capture efficiency. Sailfin mollies Poecilia latipinna displayed a high frequency of escape from traps, whereas eastern mosquitofish Gambusia holbrooki were most likely to avoid a trap once they encountered it; dollar sunfish Lepomis marginatus were least likely to avoid the trap once they encountered it or to escape once they were captured. Length of sampling and time of day affected CPUE; fishes generally had a very low retention rate over a 24 h sample time and only the Everglades pygmy sunfish Elassoma evergladei were commonly captured at night. Dispersal speed of fishes in the Florida Everglades, U.S.A., was shown to vary seasonally and among species, ranging from 0.05 to 0.15 m s-1 for small poeciliids and fundulids to 0.1 to 1.8 m s-1 for L. marginatus. Speed was generally highest late in the wet season and lowest in the dry season, possibly tied to dispersal behaviours linked to finding and remaining in dry-season refuges. These speed estimates can be used to estimate the diffusive movement rate, which is commonly employed in spatial ecological models.

  6. A MODEL EVALUATION PROTOCOL FOR URBAN SCALE FLOW AND DISPERSION MODELS

    OpenAIRE

    Di Sabatino, Silvana; Olesen, Helge; Berkowicz, Ruwim; Franke, Jörg; Schatzmann, Michael; Britter, Rex; Schlünzen, Heinke; Martilli, Alberto; Carissimo, Bertrand

    2008-01-01

    Abstract: This paper reports on a comprehensive model evaluation protocol for urban scale flow and dispersion models that has been developed within the framework of the COST action 732 on Quality Assurance and Improvement of Micro-Scale Meteorological Models. It briefly discusses the different components forming model evaluation with particular emphasis on model validation and on the implementation of the protocol for a specific test case: the MUST (Mock Urban Setting Test) experi...

  7. Analysis of meteorological parameters and its impact on atmospheric dispersion of 41Ar plume at BARC site

    International Nuclear Information System (INIS)

    A study on atmospheric dispersion of 41Ar plume was carried out considering the influence of meteorological parameters at Bhabha Atomic Research Centre site. A comparative analysis has been presented taking into account of two different observation sessions. During normal operation of research reactors, 41Ar as activation product, is getting released (below authorized discharge limit) at Bhabha Atomic Research Centre site. The external exposure during the passage of the radioactive plume was estimated using measurement of radiation field by installing Gamma-tracers at different locations. To establish a correlation and to assess the plume behavior, meteorological data and dose rate data from Gamma-tracers was collected at the same time interval

  8. 基于大气污染扩散模型的空气污染多维动态可视化表达研究%A study on multi-dimensional dynamic visualization of air pollution based on atmospheric pollution dispersion model

    Institute of Scientific and Technical Information of China (English)

    胡亚; 朱军; 林珲; 徐丙立; 胡明远

    2013-01-01

    To solve the problems that the existing methods for visualizing air pollution can not effectively integrate geographic information and can not achieve good visual effects and high-dimension information,a research on multi-dimensional dynamic visualization of air pollution in a three-dimensional space was done,based on the simulation results of the atmospheric pollution dispersion model,and a scheme for multi-dimensional dynamic visualization of air pollution was proposed.Five key technologies for visualization of air pollution,named as three-dimensional geographic scene construction for studying of air pollution,color mapping of pollution concentrations,slices-based visualization of air pollution,cubes-based visualization of air pollution and visualization of air pollution based on any vertical line or vertical plane,were described in detail.A prototype system was developed to implement five spatial and temporal visualization approaches for air pollution in the Pearl River Delta.The results prove that with the technologies addressed in this paper,high-precision and large-scale geographic information can be effectively integrated,a good visualization of air pollution can be achieved,the spatial and temporal distribution of air pollution can be effectively reflected and effective decision supports for air pollution management can be provided.%针对现有空气污染可视化表达方法不能有效集成地理信息、可视化效果差、信息维度低的问题,基于大气污染扩散模型模拟计算结果进行了三维空间空气污染多维动态可视化表达研究,提出了空气污染的多维动态可视化表达方案,详细论述了空气污染研究区域三维地理场景构建、污染浓度值与颜色的映射、基于切片的空气污染表达、基于立方体的空气污染表达、任意垂直线/面的空气污染表达等5种空间污染可视化表达方法与关键技术.最后以珠三角空气污染扩散模拟为例,

  9. Evaluating dispersion modeling options to estimate methane emissions from grazing beef cattle.

    Science.gov (United States)

    McGinn, Sean M; Flesch, Thomas K; Coates, Trevor W; Charmley, Ed; Chen, Deli; Bai, Mei; Bishop-Hurley, Greg

    2015-01-01

    Enteric methane (CH) emission from cattle is a source of greenhouse gas and is an energy loss that contributes to production inefficiency for cattle. Direct measurements of enteric CH emissions are useful to quantify the magnitude and variation and to evaluate mitigation of this important greenhouse gas source. The objectives of this study were to evaluate the impact of stocking density of cattle and source configuration (i.e., point source vs. area source and elevation of area source) on CH emissions from grazing beef cattle in Queensland, Australia. This was accomplished using nonintrusive atmospheric measurements and a gas dispersion model. The average measured CH emission for the point and area source was between 240 and 250 g animal d over the entire study. There was no difference ( > 0.05) in emission when using an elevated area source (0.5 m) or a ground area source (0 m). For the point-source configuration, there was a difference in CH emission due to stocking density; likewise, some differences existed for the area-source emissions. This study demonstrates the flexibility of the area-source configuration of the dispersion model to estimate CH emissions even at a low stocking density. PMID:25602324

  10. Modeling of hepatic elimination and organ distribution kinetics with the extended convection-dispersion model.

    Science.gov (United States)

    Roberts, M S; Anissimov, Y G

    1999-08-01

    The conventional convection-dispersion (also called axial dispersion) model is widely used to interrelate hepatic availability (F) and clearance (Cl) with the morphology and physiology of the liver and to predict effects such as changes in liver blood flow on F and Cl. An extended form of the convection-dispersion model has been developed to adequately describe the outflow concentration-time profiles for vascular markers at both short and long times after bolus injections into perfused livers. The model, based on flux concentration and a convolution of catheters and large vessels, assumes that solute elimination in hepatocytes follows either fast distribution into or radial diffusion in hepatocytes. The model includes a secondary vascular compartment, postulated to be interconnecting sinusoids. Analysis of the mean hepatic transit time (MTT) and normalized variance (CV2) of solutes with extraction showed that the discrepancy between the predictions of MTT and CV2 for the extended and unweighted conventional convection-dispersion models decreases as hepatic extraction increases. A correspondence of more than 95% in F and Cl exists for all solute extractions. In addition, the analysis showed that the outflow concentration-time profiles for both the extended and conventional models are essentially identical irrespective of the magnitude of rate constants representing permeability, volume, and clearance parameters, providing that there is significant hepatic extraction. In conclusion, the application of a newly developed extended convection-dispersion model has shown that the unweighted conventional convection-dispersion model can be used to describe the disposition of extracted solutes and, in particular, to estimate hepatic availability and clearance in both experimental and clinical situations.

  11. Swell impact on wind stress and atmospheric mixing in a regional coupled atmosphere-wave model

    DEFF Research Database (Denmark)

    Wu, Lichuan; Rutgersson, Anna; Sahlée, Erik;

    2016-01-01

    -wave-coupled regional climate model, separately and combined. The swell influence on atmospheric mixing is introduced into the atmospheric mixing length formula by adding a swell-induced contribution to the mixing. The swell influence on the wind stress under wind-following swell, moderate-range wind, and near...... reduces the near-surface wind speed. Introducing the wave influence roughness length has a larger influence than does adding the swell influence on mixing. Compared with measurements, adding the swell influence on both atmospheric mixing and wind stress gives the best model performance for the wind speed...... when developing climate models....

  12. Modelling substorm chorus events in terms of dispersive azimuthal drift

    Directory of Open Access Journals (Sweden)

    A. B. Collier

    2004-12-01

    Full Text Available The Substorm Chorus Event (SCE is a radio phenomenon observed on the ground after the onset of the substorm expansion phase. It consists of a band of VLF chorus with rising upper and lower cutoff frequencies. These emissions are thought to result from Doppler-shifted cyclotron resonance between whistler mode waves and energetic electrons which drift into a ground station's field of view from an injection site around midnight. The increasing frequency of the emission envelope has been attributed to the combined effects of energy dispersion due to gradient and curvature drifts, and the modification of resonance conditions and variation of the half-gyrofrequency cutoff resulting from the radial component of the ExB drift.

    A model is presented which accounts for the observed features of the SCE in terms of the growth rate of whistler mode waves due to anisotropy in the electron distribution. This model provides an explanation for the increasing frequency of the SCE lower cutoff, as well as reproducing the general frequency-time signature of the event. In addition, the results place some restrictions on the injected particle source distribution which might lead to a SCE.

    Key words. Space plasma physics (Wave-particle interaction – Magnetospheric physics (Plasma waves and instabilities; Storms and substorms

  13. Representing uncertainty in a spatial invasion model that incorporates human-mediated dispersal

    OpenAIRE

    Frank Koch; Denys Yemshanov; Robert Haack

    2013-01-01

    Most modes of human-mediated dispersal of invasive species are directional and vector-based. Classical spatial spread models usually depend on probabilistic dispersal kernels that emphasize distance over direction and have limited ability to depict rare but influential long-distance dispersal events. These aspects are problematic if such models are used to estimate invasion risk. Alternatively, a geographic network model may be better at estimating the typically low likelihoods associated wit...

  14. Modeling seed dispersal of black cherry, an invasive forest tree: how microsatellites may help?

    OpenAIRE

    Pairon, Marie; Jonard, Mathieu; Jacquemart, Anne-Laure

    2006-01-01

    We used empirical models and three dispersal functions (Weibull, lognormal and 2Dt) to model seed distributions derived from the black cherry (Prunus serotina Ehrh.) understorey of a pine-dominated stand. Two different approaches were used to disentangle the overlapping seed shadows: the traditional inverse modeling approach and the genetic approach that uses microsatellite markers to assign a dispersed seed to its maternal parent. The distinction was made between the seeds passively disperse...

  15. Formulations of moist thermodynamics for atmospheric modelling

    CERN Document Server

    Marquet, Pascal

    2015-01-01

    Internal energy, enthalpy and entropy are the key quantities to study thermodynamic properties of the moist atmosphere, because they correspond to the First (internal energy and enthalpy) and Second (entropy) Laws of thermodynamics. The aim of this chapter is to search for analytical formulas for the specific values of enthalpy and entropy and for the moist-air mixture composing the atmosphere. The Third Law of thermodynamics leads to the definition of absolute reference values for thermal enthalpies and entropies of all atmospheric species. It is shown in this Chapter 22 that it is possible to define and compute a general moist-air entropy potential temperature, which is really an equivalent of the moist-air specific entropy in all circumstances (saturated, or not saturated). Similarly, it is shown that it is possible to define and compute the moist-air specific enthalpy, which is different from the thermal part of what is called Moist-Static-Energy in atmospheric studies.

  16. 1-D Radiative-Convective Model for Terrestrial Exoplanet Atmospheres

    Science.gov (United States)

    Leung, Cecilia W. S.; Robinson, Tyler D.

    2016-10-01

    We present a one dimensional radiative-convective model to study the thermal structure of terrestrial exoplanetary atmospheres. The radiative transfer and equilibrium chemistry in our model is based on similar methodologies in models used for studying Extrasolar Giant Planets (Fortney et al. 2005b.) We validated our model in the optically thin and thick limits, and compared our pressure-temperature profiles against the analytical solutions of Robinson & Catling (2012). For extrasolar terrestrial planets with pure hydrogen atmospheres, we evaluated the effects of H2-H2 collision induced absorption and identified the purely roto-translational band in our modeled spectra. We also examined how enhanced atmospheric metallicities affect the temperature structure, chemistry, and spectra of terrestrial exoplanets. For a terrestrial extrasolar planet whose atmospheric compostion is 100 times solar orbiting a sun-like star at 2 AU, our model resulted in a reducing atmosphere with H2O, CH4, and NH3 as the dominant greenhouse gases.

  17. Comparisons of Transport and Dispersion Model Predictions of the Mock Urban Setting Test Field Experiment

    Science.gov (United States)

    Warner, Steve; Platt, Nathan; Heagy, James F.; Jordan, Jason E.; Bieberbach, George

    2006-10-01

    The potential effects of a terrorist attack involving the atmospheric release of chemical, biological, radiological, nuclear, or other hazardous materials continue to be of concern to the United States. The Defense Threat Reduction Agency has developed a Hazard Prediction Assessment Capability (HPAC) that includes initial features to address hazardous releases within an urban environment. Improved characterization and understanding of urban transport and dispersion are required to allow for more robust modeling. In 2001, a scaled urban setting was created in the desert of Utah using shipping containers, and tracer gases were released. This atmospheric tracer and meteorological study is known as the Mock Urban Setting Test (MUST). This paper describes the creation of sets of HPAC predictions and comparisons with the MUST field experiment. Strong consistency between the conclusions of this study and a previously reported HPAC evaluation that relied on urban tracer observations within the downtown area of Salt Lake City was found. For example, in both cases, improved predictions were associated with the inclusion of a simple empirically based urban dispersion model within HPAC, whereas improvements associated with the inclusion of a more computationally intensive wind field module were not found. The use of meteorological observations closest to the array and well above the obstacle array—the sonic anemometer measurements 16 m above ground level—resulted in predictions with the best fit to the observed tracer concentrations. The authors speculate that including meteorological observations or vertical wind profiles above or upwind of an urban region might be a sufficient input to create reasonable HPAC hazard-area predictions.

  18. Effect of Additional Structure on Effective Stack Height of Gas Dispersion in Atmosphere

    Directory of Open Access Journals (Sweden)

    Takenobu Michioka

    2016-03-01

    Full Text Available Wind-tunnel experiments were conducted to evaluate the effect of additional structure (building, sea wall and banking on the effective stack height, which is usually used in safety analyses of nuclear power facilities in Japan. The effective stack heights were estimated with and without the additional structure in addition to the reactor building while varying several conditions such as the source height, the height of additional structure and the distance between the source position and the additional structure. When the source height is equivalent to the reactor building height, the additional structure enhances both the vertical and horizontal gas dispersion widths and decreases the ground gas concentration, and it means that the additional structure does not decrease the effective stack height. When the source height is larger than the reactor height, the additional structures might affect the effective stack height. As the distance between the source and the additional structure decreases, or as the height of the additional structure increases, the structure has a larger effect on the effective stack height.

  19. Wind-tunnel tests and modeling indicate that aerial dispersant delivery operations are highly accurate

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, C.; Fritz, B. [United States Dept. of Agriculture, College Station, TX (United States); Nedwed, T. [ExxonMobil Upstream Research Co., Houston, TX (United States); Coolbaugh, T. [ExxonMobil Research and Engineering Co., Fairfax, VA (United States); Huber, C.A. [CAH Inc., Williamsburg, VA (United States)

    2009-07-01

    Oil dispersants are used to accelerate the dispersion of floating oil slicks. This study was conducted to select application equipment that will help to optimize the application oil dispersants from aircraft. Oil spill responders have a broad range of oil dispersants at their disposal because the physical and chemical interaction between the oil and dispersant is critical to successful mitigation. In order to make efficient use of dispersants, it is important to evaluate how each one atomizes once released from an aircraft. The specific goal of this study was to evaluate current spray nozzles used to spray oil dispersants from aircraft. The United States Department of Agriculture's high-speed wind tunnel facility in College Station, Texas was used to determine droplet size distributions generated by dispersant delivery nozzles at wind speeds similar to those used in aerial dispersant applications. Droplet distribution was quantified using a laser particle size analyzer. Wind-tunnel tests were conducted using water, Corexit 9500 and 9527 as well as a new dispersant gel being developed by ExxonMobil. The measured drop-size distributions were then used in an agriculture spray model to predict the delivery efficiency and swath width of dispersant delivered at flight speeds and altitudes commonly used for dispersant application. It was concluded that current practices for aerial application of dispersants lead to very efficient application. 19 refs., 5 tabs., 10 figs.

  20. Evaluation of a coupled dispersion and aerosol process model against measurements near a major road

    Directory of Open Access Journals (Sweden)

    M. A. Pohjola

    2007-02-01

    Full Text Available A field measurement campaign was conducted near a major road "Itäväylä" in an urban area in Helsinki in 17–20 February 2003. Aerosol measurements were conducted using a mobile laboratory "Sniffer" at various distances from the road, and at an urban background location. Measurements included particle size distribution in the size range of 7 nm–10 μm (aerodynamic diameter by the Electrical Low Pressure Impactor (ELPI and in the size range of 3–50 nm (mobility diameter by Scanning Mobility Particle Sizer (SMPS, total number concentration of particles larger than 3 nm detected by an ultrafine condensation particle counter (UCPC, temperature, relative humidity, wind speed and direction, driving route of the mobile laboratory, and traffic density on the studied road. In this study, we have compared measured concentration data with the predictions of the road network dispersion model CAR-FMI used in combination with an aerosol process model MONO32. The vehicular exhaust emissions, and atmospheric dispersion and transformation of fine and ultrafine particles was evaluated within the distance scale of 200 m (corresponding to a time scale of a couple of minutes. We computed the temporal evolution of the number concentrations, size distributions and chemical compositions of various particle size classes. The atmospheric dilution rate of particles is obtained from the roadside dispersion model CAR-FMI. Considering the evolution of total number concentration, dilution was shown to be the most important process. The influence of coagulation and condensation on the number concentrations of particle size modes was found to be negligible at this distance scale. Condensation was found to affect the evolution of particle diameter in the two smallest particle modes. The assumed value of the concentration of condensable organic vapour of 1012 molecules cm−3 was shown to be in a disagreement with the measured particle size evolution

  1. Quantifying atmospheric transport, chemistry, and mixing using a new trajectory-box model and a global atmospheric-chemistry GCM

    OpenAIRE

    H. Riede; Jöckel, P.; Sander, R.

    2009-01-01

    We present a novel method for the quantification of transport, chemistry, and mixing along atmospheric trajectories based on a consistent model hierarchy. The hierarchy consists of the new atmospheric-chemistry trajectory-box model CAABA/MJT and the three-dimensional (3-D) global ECHAM/MESSy atmospheric-chemistry (EMAC) general circulation model. CAABA/MJT employs the atmospheric box model CAABA in a configuration using the atmospheric-chemistry submodel MECCA (M), the photochemistry submodel...

  2. Mesoscale, Sources and Models: Sources for Nitrogen in the Atmosphere

    DEFF Research Database (Denmark)

    Hertel, O.

    1994-01-01

    Projektet Mesoscales, Sources and Models: Sources for Nitrogen in the Atmosphere er opdelt i 3 delprojekter: Sources - farmland, Sources - sea og Sources - biogenic nitrogen.......Projektet Mesoscales, Sources and Models: Sources for Nitrogen in the Atmosphere er opdelt i 3 delprojekter: Sources - farmland, Sources - sea og Sources - biogenic nitrogen....

  3. Data assimilation in the process of source term evaluation, radioactive cloud dispersion and impacts modeling

    International Nuclear Information System (INIS)

    Improved 'data assimilation' process is developed for a real time nuclear emergency response system. Our complex approach covers phenomena as follows: - State of reactor fuel and state of radiological barriers between the fuel and the atmosphere of the environment is evaluated according to really measured technological and radiological data. - Database of hypothetical source terms is pre-calculated in advance for a specific nuclear installation and various states of fuel and radiological barriers. Predicted source term is assimilated according to actual knowledge of the state of the fuel and the barriers. - The predicted source term (release by nuclides) is used for modelling on-site radiological impacts, and these calculated modeled impacts are assimilated to radiological quantities measured on-site (monitors are placed around reactor building in the area of nuclear installation). As a result, estimated 'really observed' release is evaluated. - The really observed release (by nuclides, in Bq per time interval) is used as an input to the dispersion models (Puff Trajectory Model or Lagrangean Particle Model) and the calculated offsite impacts are assimilated to radiological quantities measured offsite in close or far vicinity of the point of release. As a result, corrected activities of puffs or particles are calculated, last step of dispersion is recalculated with new inputs and correction of impacts is performed. Innovative aspect of the presented results is in the application of data assimilation process to such extent, which covers the area from the reactor up to the impacts modeled on the terrain of the environment. The described approach of the data assimilation is implemented in real time running system 'ESTE' which is a GIS based instrument used by crisis centers of Slovak NPPs and governmental emergency response centers of various countries. (author)

  4. USE OF PLUME DISPERSION MODELLING FOR VIABLE AEROSOLS FROM AN ACTIVATED SLUDGE SEWAGE TREATMENT PLANT

    Science.gov (United States)

    Predictions of the emissions of airborne total viable particle (TVP) concentrations from sewage are of concern due to possible adverse human health effects. Two types of modelling approaches were explored: dispersion modelling such as the Gaussian plume dispersion model and stati...

  5. Dispersed plug flow model for upflow anaerobic sludge bed reactors with focus on granular sludge dynamics

    NARCIS (Netherlands)

    Kalyuzhnyi, S.V.; Fedorovich, V.V.; Lens, P.N.L.

    2006-01-01

    A new approach to model upflow anaerobic sludge bed (UASB)-reactors, referred to as a one-dimensional dispersed plug flow model, was developed. This model focusses on the granular sludge dynamics along the reactor height, based on the balance between dispersion, sedimentation and convection using on

  6. Coupled groundwater-atmosphere modeling: effects on atmospheric boundary layer development

    Science.gov (United States)

    Chow, F. K.; Maxwell, R. M.; Kollet, S. J.; Daniels, M. H.; Rihani, J. F.

    2007-12-01

    Newly-developed coupled land-atmosphere models which incorporate both subsurface and atmospheric moisture dynamics have the potential to change our understanding of the hydrologic cycle. This presentation describes the effects of coupled groundwater-atmosphere modeling on simulations of the atmospheric boundary layer. Both field observations and simulations indicate strong sensitivity of atmospheric dynamics to land-surface conditions, in particular surface soil moisture. Simulations of atmospheric flow in Owens Valley (California) and in the Riviera Valley (Switzerland) show strong sensitivity to land-surface conditions, thus motivating the need for more accurate representations of soil moisture. In addition to influences from weather and seasonal changes, soil moisture dynamics respond to diurnal heat fluxes on the land surface. Using our new fully-coupled groundwater-atmosphere model, we have demonstrated correlations of soil moisture and land-surface heat fluxes with groundwater fluctuations on short, diurnal time scales. By explicitly calculating groundwater dynamics for our domain of interest, we are able to produce realistic time- and space-varying soil moisture distributions that naturally correspond to variations in topography and surface evaporation. Simulations in idealized and real watersheds are shown to illustrate these effects. The observed variations in surface moisture distribution have large impacts on the moisture and temperature structure in the atmosphere, leading to changes in boundary layer depth and convective motions as compared to standard soil moisture representations. Our coupled model framework will allow detailed investigation of the complex cycle of land-atmosphere processes affecting moisture distributions in the subsurface and the atmosphere.

  7. An Analytic Radiative-Convective Model for Planetary Atmospheres

    CERN Document Server

    Robinson, Tyler D; 10.1088/0004-637X/757/1/104

    2012-01-01

    We present an analytic 1-D radiative-convective model of the thermal structure of planetary atmospheres. Our model assumes that thermal radiative transfer is gray and can be represented by the two-stream approximation. Model atmospheres are assumed to be in hydrostatic equilibrium, with a power law scaling between the atmospheric pressure and the gray thermal optical depth. The convective portions of our models are taken to follow adiabats that account for condensation of volatiles through a scaling parameter to the dry adiabat. By combining these assumptions, we produce simple, analytic expressions that allow calculations of the atmospheric pressure-temperature profile, as well as expressions for the profiles of thermal radiative flux and convective flux. We explore the general behaviors of our model. These investigations encompass (1) worlds where atmospheric attenuation of sunlight is weak, which we show tend to have relatively high radiative-convective boundaries, (2) worlds with some attenuation of sunli...

  8. Simulations of atmospheric dispersion following a spillage of petroleum at sea

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, A.J. [Wales Univ., Unit for Coastal and Estuarine Studies, Menai Bridge (United Kingdom)

    1999-07-01

    In January 1997 7000 t of refined petrol were spilled into the English Channel following a collision in dense fog off Ostend. The following day reports of petrol odours were recorded throughout central England at Distances up to 300 km from the spill site. One possibility is that mass hysteria was induced by media reports of the accident coupled with the publicised wind direction. Indeed, the simulated gas cloud trajectory does not pass over central England if the petrol is assumed to have evaporated over a period of about 3 h. However, a feasible advection path can be reproduced by assuming that the water/atmosphere exchange of vapours occurred on a time scale of 12 h, the extended evaporation being due to the formation of subsurface droplets by wave action. Evidence to support the simulated trajectory has been obtained from the UK National Air Quality Information Archive which contains hourly data for benzene and NO{sub x} concentrations. By regressing the benzene concentration against NO{sub x} which is assumed to be an indicator of traffic density, it is shown that an increase in benzene concentrations on the day following the spillage was consistent with the simulated movement of the vapour cloud. (Author)

  9. Characterization and dispersion modeling of odors from a piggery facility.

    Science.gov (United States)

    Karageorgos, Petros; Latos, Manolis; Mpasiakos, Christos; Chalarakis, Elefterios; Dimitrakakis, Emmanuel; Daskalakis, Charis; Psillakis, Elefteria; Lazaridis, Mihalis; Kalogerakis, Nicolas

    2010-01-01

    Piggeries are known for their nuisance odors, creating problems for workers and nearby residents. Chemical substances that contribute to these odors include sulfurous organic compounds, hydrogen sulfide, phenols and indoles, ammonia, volatile amines, and volatile fatty acids. In this work, daily mean concentrations of ammonia (NH3) and hydrogen sulfide (H2S) were measured by hand-held devices. Measurements were taken in several places within the facility (farrowing to finishing rooms). Hydrogen sulfide concentration was found to be 40 to 50 times higher than the human odor threshold value in the nursery and fattening room, resulting in strong nuisance odors. Ammonia concentrations ranged from 2 to 18 mL m(-3) and also contributed to the total odor nuisance. Emission data from various chambers of the pig farm were used with the dispersion model AERMOD to determine the odor nuisance caused due to the presence of H2S and NH3 to receptors at various distances from the facility. Because just a few seconds of exposure can cause an odor nuisance, a "peak-to-mean" ratio was used to predict the maximum odor concentrations. Several scenarios were examined using the modified AERMOD program, taking into account the complex terrain around the pig farm.

  10. Modeling atmospheric deposition using a stochastic transport model

    International Nuclear Information System (INIS)

    An advanced stochastic transport model has been modified to include the removal mechanisms of dry and wet deposition. Time-dependent wind and turbulence fields are generated with a prognostic mesoscale numerical model and are used to advect and disperse individually released particles that are each assigned a mass. These particles are subjected to mass reduction in two ways depending on their physical location. Particles near the surface experience a decrease in mass using the concept of a dry deposition velocity, while the mass of particles located within areas of precipitation are depleted using a scavenging coefficient. Two levels of complexity are incorporated into the particle model. The simple case assumes constant values of dry deposition velocity and scavenging coefficient, while the more complex case varies the values according to meteorology, surface conditions, release material, and precipitation intensity. Instantaneous and cumulative dry and wet deposition are determined from the mass loss due to these physical mechanisms. A useful means of validating the model results is with data available from a recent accidental release of Cesium-137 from a steel-processing furnace in Algeciras, Spain in May, 1998. This paper describes the deposition modeling technique, as well as a comparison of simulated concentration and deposition with measurements taken for the Algeciras release

  11. MODELING DISPERSION FROM CHEMICALS RELEASED AFTER A TRAIN COLLISION IN GRANITEVILLE, SOUTH CAROLINA

    Energy Technology Data Exchange (ETDEWEB)

    Buckley, R; Chuck Hunter, C; Robert Addis, R; Matt Parker, M

    2006-08-07

    The Savannah River National Laboratory's (SRNL) Weather INformation and Display (WIND) System was used to provide meteorological and atmospheric modeling/consequence assessment support to state and local agencies following the collision of two Norfolk Southern freight trains on the morning of January 6, 2005. This collision resulted in the release of several toxic chemicals to the environment, including chlorine. The dense and highly toxic cloud of chlorine gas that formed in the vicinity of the accident was responsible for nine fatalities, and caused injuries to more than five hundred others. Transport model results depicting the forecast path of the ongoing release were made available to emergency managers in the county's Unified Command Center shortly after SRNL received a request for assistance. Support continued over the ensuing two days of the active response. The SRNL also provided weather briefings and transport/consequence assessment model results to responders from South Carolina Department of Health and Environmental Control (SCDHEC), the Savannah River Site's (SRS) Emergency Operations Center (EOC), Department of Energy Headquarters, and hazmat teams dispatched from the SRS. Although model-generated forecast winds used in consequence assessments conducted during the incident were provided at 2-km horizontal grid spacing during the accident response, a high-resolution Regional Atmospheric Modeling System (RAMS, version 4.3.0) simulation was later performed to examine potential influences of local topography on plume migration. The detailed RAMS simulation was used to determine meteorology using multiple grids with an innermost grid spacing of 125 meters. Results from the two simulations are shown to generally agree with meteorological observations at the time; consequently, local topography did not significantly affect wind in the area. Use of a dense gas dispersion model to simulate localized plume behavior using the higher resolution

  12. Modeling dispersion from toxic gas released after a train collision in Graniteville, SC.

    Science.gov (United States)

    Buckley, Robert L; Hunter, Charles H; Addis, Robert P; Parker, Matthew J

    2007-03-01

    The Savannah River National Laboratory (SRNL) Weather Information and Display System was used to provide meteorological and atmospheric modeling/consequence assessment support to state and local agencies after the collision of two Norfolk Southern freight trains on the morning of January 6, 2005. This collision resulted in the release of several toxic chemicals to the environment, including chlorine. The dense and highly toxic cloud of chlorine gas that formed in the vicinity of the accident was responsible for 9 fatalities and caused injuries to more than 500 others. Transport model results depicting the forecast path of the ongoing release were made available to emergency managers in the county's Unified Command Center shortly after SRNL received a request for assistance. Support continued over the ensuing 2 days of the active response. The SRNL also provided weather briefings and transport/consequence assessment model results to responders from the South Carolina Department of Health and Environmental Control, the Savannah River Site (SRS) Emergency Operations Center, Department of Energy headquarters, and hazard material teams dispatched from the SRS. Operational model-generated forecast winds used in consequence assessments conducted during the incident were provided at 2-km horizontal grid spacing during the accident response. High-resolution Regional Atmospheric Modeling System (RAMS, version 4.3.0) simulation was later performed to examine potential influences of local topography on plume migration in greater detail. The detailed RAMS simulation was used to determine meteorology using multiple grids with an innermost grid spacing of 125 m. Results from the two simulations are shown to generally agree with meteorological observations at the time; consequently, local topography did not significantly affect wind in the area. Use of a dense gas dispersion model to simulate localized plume behavior using the higher-resolution winds indicated agreement with

  13. A WEAKLY NONLINEAR WATER WAVE MODEL TAKING INTO ACCOUNT DISPERSION OF WAVE PHASE VELOCITY

    Institute of Scientific and Technical Information of China (English)

    李瑞杰; 李东永

    2002-01-01

    This paper presents a weakly nonlinear water wave model using a mild slope equation and a new explicit formulation which takes into account dispersion of wave phase velocity, approximates Hedges' (1987) nonlinear dispersion relationship, and accords well with the original empirical formula. Comparison of the calculating results with those obtained from the experimental data and those obtained from linear wave theory showed that the present water wave model considering the dispersion of phase velocity is rational and in good agreement with experiment data.

  14. Computational modelling of pollution dispersion in the near wake of a vehicle

    OpenAIRE

    Richards, Kathryn

    2003-01-01

    The feasibility of using CFD to model the dispersion of pollutant in the near wake of a model vehicle was investigated through a series of experimental and computational studies. The near wake structure of the MIRA 33% scale reference vehicle (fastback) was measured using Particle Image Velocimetry (PIV), and hotwire anemometry and the dispersion of a tracer measured using Flame Ionisation Detectors (FIDs). The experimental data not only provided insight into the dispersion character of the m...

  15. Mathematical modeling of pigment dispersion taking into account the full agglomerate particle size distribution

    DEFF Research Database (Denmark)

    Kiil, Søren

    2016-01-01

    The purpose of this work is to develop a mathematical model that can quantify the dispersion of pigments, with a focus on the mechanical breakage of pigment agglomerates. The underlying physical mechanism was assumed to be surface erosion of spherical pigment agglomerates. The full agglomerate pa.......g., in the development of novel dispersion principles and for analysis of dispersion failures. The general applicability of the model, beyond the three pigments considered, needs to be confirmed....

  16. A generalized Brownian motion model for turbulent relative particle dispersion

    Science.gov (United States)

    Shivamoggi, B. K.

    2016-08-01

    There is speculation that the difficulty in obtaining an extended range with Richardson-Obukhov scaling in both laboratory experiments and numerical simulations is due to the finiteness of the flow Reynolds number Re in these situations. In this paper, a generalized Brownian motion model has been applied to describe the relative particle dispersion problem in more realistic turbulent flows and to shed some light on this issue. The fluctuating pressure forces acting on a fluid particle are taken to be a colored noise and follow a stationary process and are described by the Uhlenbeck-Ornstein model while it appears plausible to take their correlation time to have a power-law dependence on Re, thus introducing a bridge between the Lagrangian quantities and the Eulerian parameters for this problem. This ansatz is in qualitative agreement with the possibility of a connection speculated earlier by Corrsin [26] between the white-noise representation for the fluctuating pressure forces and the large-Re assumption in the Kolmogorov [4] theory for the 3D fully developed turbulence (FDT) as well as a similar argument of Monin and Yaglom [23] and a similar result of Sawford [13] and Borgas and Sawford [24]. It also provides an insight into the result that the Richardson-Obukhov scaling holds only in the infinite-Re limit and disappears otherwise. This ansatz further provides a determination of the Richardson-Obukhov constant g as a function of Re, with an asymptotic constant value in the infinite-Re limit. It is shown to lead to full agreement, in the small-Re limit as well, with the Batchelor-Townsend [27] scaling for the rate of change of the mean square interparticle separation in 3D FDT, hence validating its soundness further.

  17. Dispersion Modeling and Characterization of Particulates from Land Application of Class B Biosolids

    Science.gov (United States)

    Bhat, Abhishek S.

    This study presents a comprehensive approach to understand the particle characteristics, identify the source profile, develop new equations for emission rates, analyze the source-receptor relationship, and develop and evaluate a numerical model for the dispersion and transport of particles released during the injection of biosolids. Two field studies were conducted in the summer of 2008 and 2009 to collect airborne particulate matter emitted during the injection application of class B biosolids. The sampling was carried out before (pre-application), during (application), and after (post-application) the application. The research work characterized the particulate emissions deposited on the aerosols spectrometer. The mass concentrations of fine (PM2.5) and ultrafine (PM 1.0) particles were highest during the pre-application. The mass concentration of thoracic fraction (PM2.5-10) increased significantly during the application. A bimodal size distribution was observed throughout the sampling. Nuclei mode formation was predominant during the pre-application and the post-application, whereas the accumulation mode was distinctive during the application. Airborne particles were collected on filter papers during the biosolids application process using an aerosol spectrometer. Scanning electron microscopy (SEM) coupled with an energy dispersive spectrometry (EDS) tool was used to analyze particles collected before, during, and after injection of biosolids. The major emphasis of the analysis was on providing in depth information on particle count, size, shape, morphology, and chemical composition. The particle count was significantly sensitive towards the different activities surrounding the application. The combination of SEM, particle analysis software, and EDS technique was capable of revealing detailed information on the size, shape, morphology, and chemical composition of individual particles. These techniques proved to be an effective non-destructive method for the

  18. Future developments in modelling and monitoring of volcanic ash clouds: outcomes from the first IAVCEI-WMO workshop on Ash Dispersal Forecast and Civil Aviation

    Science.gov (United States)

    Bonadonna, Costanza; Folch, Arnau; Loughlin, Susan; Puempel, Herbert

    2012-01-01

    As a result of the serious consequences of the 2010 Eyjafjallajökull eruption (Iceland) on civil aviation, 52 volcanologists, meteorologists, atmospheric dispersion modellers and space and ground-based monitoring specialists from 12 different countries (including representatives from 6 Volcanic Ash Advisory Centres and related institutions) gathered to discuss the needs of the ash dispersal modelling community, investigate new data-acquisition strategies (i.e. quantitative measurements and observations) and discuss how to improve communication between the research community and institutions with an operational mandate. Based on a dedicated benchmark exercise and on 3 days of in-depth discussion, recommendations have been made for future model improvements, new strategies of ash cloud forecasting, multidisciplinary data acquisition and more efficient communication between different communities. Issues addressed in the workshop include ash dispersal modelling, uncertainty, ensemble forecasting, combining dispersal models and observations, sensitivity analysis, model variability, data acquisition, pre-eruption forecasting, first simulation and data assimilation, research priorities and new communication strategies to improve information flow and operational routines. As a main conclusion, model developers, meteorologists, volcanologists and stakeholders need to work closely together to develop new and improved strategies for ash dispersal forecasting and, in particular, to: (1) improve the definition of the source term, (2) design models and forecasting strategies that can better characterize uncertainties, (3) explore and identify the best ensemble strategies that can be adapted to ash dispersal forecasting, (4) identify optimized strategies for the combination of models and observations and (5) implement new critical operational strategies.

  19. Revisiting the Impact of Atmospheric Dispersion and Differential Refraction on Widefield Multiobject Spectroscopic Observations. From VLT/VIMOS to Next Generation Instruments

    CERN Document Server

    Sánchez-Janssen, Rubén; Selman, Fernando; Bristow, Paul; Hammersley, Peter; Hilker, Michael; Rejkuba, Marina; Wolff, Burkhard

    2014-01-01

    (Abridged) Atmospheric dispersion and field differential refraction impose severe constraints on widefield MOS observations. Flux reduction and spectral distortions must be minimised by a careful planning of the observations -- which is especially true for instruments that use slits instead of fibres. This is the case of VIMOS at the VLT, where MOS observations have been restricted, since the start of operations, to a narrow two-hour range from the meridian to minimise slit losses. We revisit in detail the impact of atmospheric effects on the quality of VIMOS-MOS spectra. We model slit losses across the entire VIMOS FOV as a function of target declination. We explore two different slit orientations at the meridian: along the parallactic angle (North-South), and perpendicular to it (East-West). We show that, for fields culminating at zenith distances larger than 20 deg, slit losses are minimised with slits oriented along the parallactic angle at the meridian. The two-hour angle rule holds for these observation...

  20. Distorted-distance models for directional dispersal: a general framework with application to a wind-dispersed tree

    NARCIS (Netherlands)

    Putten, van B.; Visser, M.D.; Muller-Landau, H.C.; Jansen, P.A.

    2012-01-01

    1. Seed and pollen dispersal is often directionally biased, because of the inherent directionality of wind and many other dispersal vectors. Nevertheless, the vast majority of studies of seed and pollen dispersal fit isotropic dispersal kernels to data, implicitly assuming that dispersal is equally

  1. Optimal weighted combinatorial forecasting model of QT dispersion of ECGs in Chinese adults

    Science.gov (United States)

    Wen, Zhang; Miao, Ge; Xinlei, Liu; Minyi, Cen

    2016-07-01

    This study aims to provide a scientific basis for unifying the reference value standard of QT dispersion of ECGs in Chinese adults. Three predictive models including regression model, principal component model, and artificial neural network model are combined to establish the optimal weighted combination model. The optimal weighted combination model and single model are verified and compared. Optimal weighted combinatorial model can reduce predicting risk of single model and improve the predicting precision. The reference value of geographical distribution of Chinese adults' QT dispersion was precisely made by using kriging methods. When geographical factors of a particular area are obtained, the reference value of QT dispersion of Chinese adults in this area can be estimated by using optimal weighted combinatorial model and reference value of the QT dispersion of Chinese adults anywhere in China can be obtained by using geographical distribution figure as well.

  2. Dispersal distances for airborne spores based on deposition rates and stochastic modeling

    DEFF Research Database (Denmark)

    Stockmarr, Anders; Andreasen, Viggo; Østergård, Hanne

    2007-01-01

    A new modeling framework for particle dispersal is explored in the context of the particles being fungal spores dispersed within a field. The model gives rise to both exponentially decreasing and polynomially decreasing two-dimensional densities of deposited fungal spores. We reformulate the mode...

  3. Dairy farm methane emissions using a dispersion model.

    Science.gov (United States)

    McGinn, S M; Beauchemin, K A

    2012-01-01

    There is a need to know whole-farm methane (CH(4)) emissions since confined animal facilities such as beef cattle feedlots and dairy farms are emission "hot spots" in the landscape. However, measurements of whole-farm CH(4) emissions can differ between farms because of differences in contributing sources such as manure handling, number of lactating and nonlactating cows, and diet. Such differences may limit the usefulness of whole-farm emissions for national inventories and mitigation purposes unless the variance between farms is taken into account or a large number of farms can be examined. Our study describes the application of a dispersion model used in conjunction with field measurements of CH(4) concentration and stability of the air to calculate whole-farm emissions of CH(4) from three dairy farms in Alberta, Canada, during three sequential campaigns conducted in November 2004 and May and July 2005. The dairy farms ranged in herd size from 208 to 351 cows (102 to 196 lactating cows) and had different manure handling operations. The results indicate that the average CH(4) emission per cow (mixture of lactating and nonlactating) from the three dairy farms was 336 g d(-1), which was reduced to 271 g d(-1) when the emission (estimated) from the manure storage was removed. Further separation of source strength yielded an average CH(4) (enteric) emission of 363 g d(-1) for a lactating cow. The estimated CH(4) emission intensities were approximately 15 g CH(4) kg(-1) dry matter intake and 16.7 L CH(4) L(-1) of milk produced. The approach of understanding the farm-to-farm differences in CH(4) emissions as affected by diet, animal type, and manure management is essential when utilizing whole-farm emission measurements for mitigation and inventory applications. PMID:22218175

  4. Estimate Total Number of the Earth Atmospheric Particle with Standard Atmosphere Model

    Institute of Scientific and Technical Information of China (English)

    GAO Chong-Yi

    2001-01-01

    The total number of atmospheric particle (AP) is an important datum for planetary science and geoscience.Estimating entire AP number is also a familiar question in general physics.With standard atmosphere model,considering the number difference of AP caused by rough and uneven in the earth surface below,the sum of dry clean atmosphere particle is 1.06962 × 1044.So the whole number of AP including water vapor is 1.0740 × 1044.The rough estimation for the total number of AP on other planets (or satellites) in condensed state is also discussed on the base of it.

  5. Mercury emission and dispersion models from soils contaminated by cinnabar mining and metallurgy.

    Science.gov (United States)

    Llanos, Willians; Kocman, David; Higueras, Pablo; Horvat, Milena

    2011-12-01

    The laboratory flux measurement system (LFMS) and dispersion models were used to investigate the kinetics of mercury emission flux (MEF) from contaminated soils. Representative soil samples with respect to total Hg concentration (26-9770 μg g(-1)) surrounding a decommissioned mercury-mining area (Las Cuevas Mine), and a former mercury smelter (Cerco Metalúrgico de Almadenejos), in the Almadén mercury mining district (South Central Spain), were collected. Altogether, 14 samples were analyzed to determine the variation in mercury emission flux (MEF) versus distance from the sources, regulating two major environmental parameters comprising soil temperature and solar radiation. In addition, the fraction of the water-soluble mercury in these samples was determined in order to assess how MEF from soil is related to the mercury in the aqueous soil phase. Measured MEFs ranged from less than 140 to over 10,000 ng m(-2) h(-1), with the highest emissions from contaminated soils adjacent to point sources. A significant decrease of MEF was then observed with increasing distance from these sites. Strong positive effects of both temperature and solar radiation on MEF was observed. Moreover, MEF was found to occur more easily in soils with higher proportions of soluble mercury compared to soils where cinnabar prevails. Based on the calculated Hg emission rates and with the support of geographical information system (GIS) tools and ISC AERMOD software, dispersion models for atmospheric mercury were implemented. In this way, the gaseous mercury plume generated by the soil-originated emissions at different seasons was modeled. Modeling efforts revealed that much higher emissions and larger mercury plumes are generated in dry and warm periods (summer), while the plume is smaller and associated with lower concentrations of atmospheric mercury during colder periods with higher wind activity (fall). Based on the calculated emissions and the model implementation, yearly emissions from

  6. A theoretical model of atmospheric ozone depletion

    Science.gov (United States)

    Midya, S. K.; Jana, P. K.; Lahiri, T.

    1994-01-01

    A critical study on different ozone depletion and formation processes has been made and following important results are obtained: (i) From analysis it is shown that O3 concentration will decrease very minutely with time for normal atmosphere when [O], [O2] and UV-radiation remain constant. (ii) An empirical equation is established theoretically between the variation of ozone concentration and time. (iii) Special ozone depletion processes are responsible for the dramatic decrease of O3-concentration at Antarctica.

  7. Modelling the dispersion of vehicle-emitted pollutants

    Energy Technology Data Exchange (ETDEWEB)

    McCrae, I.S.; Hamilton, R.S.; Revitt, D.M. (Middlesex Polytechnic, Middlesex (GB)); Harrop, D.O. (Tottenham College, London (GB))

    1988-01-01

    It is well known that certain vehicle-generated air pollutants may have adverse effects on human health, ecosystems and amenity. For many years, carbon monoxide and lead were the pollutants which received most attention. However, other problems have been identified, principally the role of nitrogen oxides in producing acid rain, the mutagenic and carcinogenic effects of polyaromatic hydrocarbons and the darkness of diesel-emitted smoke. The magnitude of some of the problems has been compounded by changes in engine design and fuel composition. An understanding of the impact of vehicle-emitted pollutants on the environment requires a knowledge of the processes which control their transport through the atmosphere. Short-range transport processes are best investigated using field data collected near to a rural motorway since in that situation the source is a well-defined line to which standard mathematical modelling techniques can be applied and non-vehicle sources of pollution are reduced to a minimum. This paper examines the use of desk-top and computer-based techniques to predict CO concentrations.

  8. Effective pollutant emission heights for atmospheric transport modelling based on real-world information

    International Nuclear Information System (INIS)

    Emission data needed as input for the operation of atmospheric models should not only be spatially and temporally resolved. Another important feature is the effective emission height which significantly influences modelled concentration values. Unfortunately this information, which is especially relevant for large point sources, is usually not available and simple assumptions are often used in atmospheric models. As a contribution to improve knowledge on emission heights this paper provides typical default values for the driving parameters stack height and flue gas temperature, velocity and flow rate for different industrial sources. The results were derived from an analysis of the probably most comprehensive database of real-world stack information existing in Europe based on German industrial data. A bottom-up calculation of effective emission heights applying equations used for Gaussian dispersion models shows significant differences depending on source and air pollutant and compared to approaches currently used for atmospheric transport modelling. - The comprehensive analysis of real-world stack data provides detailed default parameter values for improving vertical emission distribution in atmospheric modelling

  9. Numerical Considerations for Lagrangian Stochastic Dispersion Models: Eliminating Rogue Trajectories, and the Importance of Numerical Accuracy

    Science.gov (United States)

    Bailey, Brian N.

    2016-07-01

    When Lagrangian stochastic models for turbulent dispersion are applied to complex atmospheric flows, some type of ad hoc intervention is almost always necessary to eliminate unphysical behaviour in the numerical solution. Here we discuss numerical strategies for solving the non-linear Langevin-based particle velocity evolution equation that eliminate such unphysical behaviour in both Reynolds-averaged and large-eddy simulation applications. Extremely large or `rogue' particle velocities are caused when the numerical integration scheme becomes unstable. Such instabilities can be eliminated by using a sufficiently small integration timestep, or in cases where the required timestep is unrealistically small, an unconditionally stable implicit integration scheme can be used. When the generalized anisotropic turbulence model is used, it is critical that the input velocity covariance tensor be realizable, otherwise unphysical behaviour can become problematic regardless of the integration scheme or size of the timestep. A method is presented to ensure realizability, and thus eliminate such behaviour. It was also found that the numerical accuracy of the integration scheme determined the degree to which the second law of thermodynamics or `well-mixed condition' was satisfied. Perhaps more importantly, it also determined the degree to which modelled Eulerian particle velocity statistics matched the specified Eulerian distributions (which is the ultimate goal of the numerical solution). It is recommended that future models be verified by not only checking the well-mixed condition, but perhaps more importantly by checking that computed Eulerian statistics match the Eulerian statistics specified as inputs.

  10. Highly physical penumbra solar radiation pressure modeling with atmospheric effects

    Science.gov (United States)

    Robertson, Robert; Flury, Jakob; Bandikova, Tamara; Schilling, Manuel

    2015-10-01

    We present a new method for highly physical solar radiation pressure (SRP) modeling in Earth's penumbra. The fundamental geometry and approach mirrors past work, where the solar radiation field is modeled using a number of light rays, rather than treating the Sun as a single point source. However, we aim to clarify this approach, simplify its implementation, and model previously overlooked factors. The complex geometries involved in modeling penumbra solar radiation fields are described in a more intuitive and complete way to simplify implementation. Atmospheric effects are tabulated to significantly reduce computational cost. We present new, more efficient and accurate approaches to modeling atmospheric effects which allow us to consider the high spatial and temporal variability in lower atmospheric conditions. Modeled penumbra SRP accelerations for the Gravity Recovery and Climate Experiment (GRACE) satellites are compared to the sub-nm/s2 precision GRACE accelerometer data. Comparisons to accelerometer data and a traditional penumbra SRP model illustrate the improved accuracy which our methods provide. Sensitivity analyses illustrate the significance of various atmospheric parameters and modeled effects on penumbra SRP. While this model is more complex than a traditional penumbra SRP model, we demonstrate its utility and propose that a highly physical model which considers atmospheric effects should be the basis for any simplified approach to penumbra SRP modeling.

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

    Directory of Open Access Journals (Sweden)

    L. Menut

    2013-07-01

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

  12. AIR DISPERSION MODELING AT THE WASTE ISOLATION PILOT PLANT

    Energy Technology Data Exchange (ETDEWEB)

    Rucker, D.F.

    2000-08-01

    One concern at the Waste Isolation Pilot Plant (WIPP) is the amount of alpha-emitting radionuclides or hazardous chemicals that can become airborne at the facility and reach the Exclusive Use Area boundary as the result of a release from the Waste Handling Building (WHB) or from the underground during waste emplacement operations. The WIPP Safety Analysis Report (SAR), WIPP RCRA Permit, and WIPP Emergency Preparedness Hazards Assessments include air dispersion calculations to address this issue. Meteorological conditions at the WIPP facility will dictate direction, speed, and dilution of a contaminant plume of respirable material due to chronic releases or during an accident. Due to the paucity of meteorological information at the WIPP site prior to September 1996, the Department of Energy (DOE) reports had to rely largely on unqualified climatic data from the site and neighboring Carlsbad, which is situated approximately 40 km (26 miles) to the west of the site. This report examines the validity of the DOE air dispersion calculations using new meteorological data measured and collected at the WIPP site since September 1996. The air dispersion calculations in this report include both chronic and acute releases. Chronic release calculations were conducted with the EPA-approved code, CAP88PC and the calculations showed that in order for a violation of 40 CFR61 (NESHAPS) to occur, approximately 15 mCi/yr of 239Pu would have to be released from the exhaust stack or from the WHB. This is an extremely high value. Hence, it is unlikely that NESHAPS would be violated. A site-specific air dispersion coefficient was evaluated for comparison with that used in acute dose calculations. The calculations presented in Section 3.2 and 3.3 show that one could expect a slightly less dispersive plume (larger air dispersion coefficient) given greater confidence in the meteorological data, i.e. 95% worst case meteorological conditions. Calculations show that dispersion will decrease

  13. Memory efficient atmospheric effects modeling for infrared scene generators

    Science.gov (United States)

    Kavak, Çaǧlar; Özsaraç, Seçkin

    2015-05-01

    The infrared (IR) energy radiated from any source passes through the atmosphere before reaching the sensor. As a result, the total signature captured by the IR sensor is significantly modified by the atmospheric effects. The dominant physical quantities that constitute the mentioned atmospheric effects are the atmospheric transmittance and the atmospheric path radiance. The incoming IR radiation is attenuated by the transmittance and path radiance is added on top of the attenuated radiation. In IR scene simulations OpenGL is widely used for rendering purposes. In the literature there are studies, which model the atmospheric effects in an IR band using OpenGLs exponential fog model as suggested by Beers law. In the standard pipeline of OpenGL, the related fog model needs single equivalent OpenGL variables for the transmittance and path radiance, which actually depend on both the distance between the source and the sensor and also on the wavelength of interest. However, in the conditions where the range dependency cannot be modeled as an exponential function, it is not accurate to replace the atmospheric quantities with a single parameter. The introduction of OpenGL Shading Language (GLSL) has enabled the developers to use the GPU more flexible. In this paper, a novel method is proposed for the atmospheric effects modeling using the least squares estimation with polynomial fitting by programmable OpenGL shader programs built with GLSL. In this context, a radiative transfer model code is used to obtain the transmittance and path radiance data. Then, polynomial fits are computed for the range dependency of these variables. Hence, the atmospheric effects model data that will be uploaded in the GPU memory is significantly reduced. Moreover, the error because of fitting is negligible as long as narrow IR bands are used.

  14. Shortcomings of the standard Lennard-Jones dispersion term in water models, studied with force matching

    OpenAIRE

    Nicolini, Paolo; Guàrdia Manuel, Elvira; Masia, Marco

    2013-01-01

    In this work, ab initio parametrization of water force field is used to get insights into the functional form of empirical potentials to properly model the physics underlying dispersion interactions. We exploited the force matching algorithm to fit the interaction forces obtained with dispersion corrected density functional theory based molecular dynamics simulations. We found that the standard Lennard-Jones interaction potentials poorly reproduce the attractive character of dispersion forces...

  15. Atmospheric radionuclide transport model with radon postprocessor and SBG module. Model description version 2.8.0; ARTM. Atmosphaerisches Radionuklid-Transport-Modell mit Radon Postprozessor und SBG-Modul. Modellbeschreibung zu Version 2.8.0

    Energy Technology Data Exchange (ETDEWEB)

    Richter, Cornelia; Sogalla, Martin; Thielen, Harald; Martens, Reinhard

    2015-04-20

    The study on the atmospheric radionuclide transport model with radon postprocessor and SBG module (model description version 2.8.0) covers the following issues: determination of emissions, radioactive decay, atmospheric dispersion calculation for radioactive gases, atmospheric dispersion calculation for radioactive dusts, determination of the gamma cloud radiation (gamma submersion), terrain roughness, effective source height, calculation area and model points, geographic reference systems and coordinate transformations, meteorological data, use of invalid meteorological data sets, consideration of statistical uncertainties, consideration of housings, consideration of bumpiness, consideration of terrain roughness, use of frequency distributions of the hourly dispersion situation, consideration of the vegetation period (summer), the radon post processor radon.exe, the SBG module, modeling of wind fields, shading settings.

  16. Revisiting the Carrington Event: Updated modeling of atmospheric effects

    CERN Document Server

    Thomas, Brian C; Snyder, Brock R

    2011-01-01

    The terrestrial effects of major solar events such as the Carrington white-light flare and subsequent geomagnetic storm of August-September 1859 are of considerable interest, especially in light of recent predictions that such extreme events will be more likely over the coming decades. Here we present results of modeling the atmospheric effects, especially production of odd nitrogen compounds and subsequent depletion of ozone, by solar protons associated with the Carrington event. This study combines approaches from two previous studies of the atmospheric effect of this event. We investigate changes in NOy compounds as well as depletion of O3 using a two-dimensional atmospheric chemistry and dynamics model. Atmospheric ionization is computed using a range-energy relation with four different proxy proton spectra associated with more recent well-known solar proton events. We find that changes in atmospheric constituents are in reasonable agreement with previous studies, but effects of the four proxy spectra use...

  17. Comparison of modelled and empirical atmospheric propagation data

    Science.gov (United States)

    Schott, J. R.; Biegel, J. D.

    1983-01-01

    The radiometric integrity of TM thermal infrared channel data was evaluated and monitored to develop improved radiometric preprocessing calibration techniques for removal of atmospheric effects. Modelled atmospheric transmittance and path radiance were compared with empirical values derived from aircraft underflight data. Aircraft thermal infrared imagery and calibration data were available on two dates as were corresponding atmospheric radiosonde data. The radiosonde data were used as input to the LOWTRAN 5A code which was modified to output atmospheric path radiance in addition to transmittance. The aircraft data were calibrated and used to generate analogous measurements. These data indicate that there is a tendancy for the LOWTRAN model to underestimate atmospheric path radiance and transmittance as compared to empirical data. A plot of transmittance versus altitude for both LOWTRAN and empirical data is presented.

  18. Meteorological Modeling Using the WRF-ARW Model for Grand Bay Intensive Studies of Atmospheric Mercury

    Directory of Open Access Journals (Sweden)

    Fong Ngan

    2015-02-01

    Full Text Available Measurements at the Grand Bay National Estuarine Research Reserve support a range of research activities aimed at improving the understanding of the atmospheric fate and transport of mercury. Routine monitoring was enhanced by two intensive measurement periods conducted at the site in summer 2010 and spring 2011. Detailed meteorological data are required to properly represent the weather conditions, to determine the transport and dispersion of plumes and to understand the wet and dry deposition of mercury. To describe the mesoscale features that might influence future plume calculations for mercury episodes during the Grand Bay Intensive campaigns, fine-resolution meteorological simulations using the Weather Research and Forecasting (WRF model were conducted with various initialization and nudging configurations. The WRF simulations with nudging generated reasonable results in comparison with conventional observations in the region and measurements obtained at the Grand Bay site, including surface and sounding data. The grid nudging, together with observational nudging, had a positive effect on wind prediction. However, the nudging of mass fields (temperature and moisture led to overestimates of precipitation, which may introduce significant inaccuracies if the data were to be used for subsequent atmospheric mercury modeling. The regional flow prediction was also influenced by the reanalysis data used to initialize the WRF simulations. Even with observational nudging, the summer case simulation results in the fine resolution domain inherited features of the reanalysis data, resulting in different regional wind patterns. By contrast, the spring intensive period showed less influence from the reanalysis data.

  19. Revisions to Photochemical Data for Use in Atmospheric Modeling

    Science.gov (United States)

    Shutter, Joshua D.; Willacy, Karen; Allen, Mark

    2012-01-01

    Solar and stellar flux incident on an atmosphere can cause molecules to dissociate into highly reactive species and allows for photochemical processes to play a fundamental role in atmospheric chemistry. While models have tried to simulate such processes, they are extremely sensitive to photoabsorption cross-sections and quantum yields: two parameters that are important in determining the photodissociation rate, and hence the lifetime, of atmospheric compounds. Obtaining high-resolution and current data for these parameters is therefore highly desirable. Due to this, database and literature searches for high-quality cross-sections and quantum yields were performed and compiled for KINETICS, a Caltech/JPL Chemical Transport Model that can be used in modeling planetary atmospheres. Furthermore, photodissociation rates determined by running a Titan 1-D model were used to verify the completeness of these latest revisions.

  20. Weather Research and Forecasting (WRF) Regional Atmospheric Model: CNMI

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Weather Research and Forecasting (WRF) mesoscale numerical weather prediction model 7-day hourly forecast for the region surrounding the Commonwealth of the...

  1. Weather Research and Forecasting (WRF) Regional Atmospheric Model: Samoa

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Weather Research and Forecasting (WRF) mesoscale numerical weather prediction model 7-day hourly forecast for the region surrounding the islands of Samoa at...

  2. Weather Research and Forecasting (WRF) Regional Atmospheric Model: Oahu

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Weather Research and Forecasting (WRF) mesoscale numerical weather prediction model 3.5-day hourly forecast for the region surrounding the Hawaiian island of Oahu...

  3. A New Titan Atmospheric Model for Mission Engineering Applications

    Science.gov (United States)

    Waite, J. H.; Bell, J. M.; Lorenz, R.; Achterberg, R.; Flasar, F. M.

    2012-03-01

    Titan’s polar regions and hydrocarbon lakes are of interest for future exploration. This paper describes a new engineering model of Titan’s atmospheric structure with particular reference to the proposed Titan Mare Explorer mission.

  4. [Hyperspectral Detection Model for Soil Dispersion in Zhouqu Debris Flow Source Region].

    Science.gov (United States)

    Wang, Qin-jun; Wei, Yong-ming; Chen, Yu; Chen, Jia-ge; Lin, Qi-zhong

    2016-02-01

    Sensitive band positions, models and the principles of soil dispersion detected by hyperspectral remote sensing were firstly discussed according to the results of soil dispersive hyperspectral remote sensing experiment. Results showed that, (1) signals and noises could be separated by Fourier transformation. A finely mineral identification system was developed to remove spectral noises and provide highly accurate data for establishing soil dispersive model; (2) Soil dispersive hyperspectral remote sensing model established by the multiple linear regression method was good at soil dispersion forecasting for the high correlation between sensitive bands and the soil dispersions. (3) According to mineral spectra, soil minerals and their absorbed irons were reflected by sensitive bands which revealed reasons causing soils to be dispersive. Sodium was the closest iron correlated with soil dispersion. The secondary was calcite, montmorillonite and illite. However, the correlation between soil dispersion and chlorite, kaolinite, PH value, quartz, potassium feldspar, plagioclase was weak. The main reason was probably that sodium was low in ionic valence, small ionic radius and strong hydration forces; calcite was high water soluble and illite was weak binding forces between two layers under high pH value. PMID:27209758

  5. Nonlocal dispersive optical model ingredients for ${}^{40}$Ca

    CERN Document Server

    Mahzoon, M H; Dickhoff, W H; Dussan, H; Waldecker, S J

    2013-01-01

    A comprehensive description of all single-particle properties associated with the nucleus ${}^{40}$Ca has been generated by employing a nonlocal dispersive optical potential capable of simultaneously reproducing all relevant data above and below the Fermi energy. We gather all relevant functional forms and the numerical values of the parameters in this contribution.

  6. Finite-difference numerical modelling of gravitoacoustic wave propagation in a windy and attenuating atmosphere

    Science.gov (United States)

    Brissaud, Quentin; Martin, Roland; Garcia, Raphaël F.; Komatitsch, Dimitri

    2016-07-01

    Acoustic and gravity waves propagating in planetary atmospheres have been studied intensively as markers of specific phenomena such as tectonic events or explosions or as contributors to atmosphere dynamics. To get a better understanding of the physics behind these dynamic processes, both acoustic and gravity waves propagation should be modelled in a 3-D attenuating and windy atmosphere extending from the ground to the upper thermosphere. Thus, in order to provide an efficient numerical tool at the regional or global scale, we introduce a finite difference in the time domain (FDTD) approach that relies on the linearized compressible Navier-Stokes equations with a background flow (wind). One significant benefit of such a method is its versatility because it handles both acoustic and gravity waves in the same simulation, which enables one to observe interactions between them. Simulations can be performed for 2-D or 3-D realistic cases such as tsunamis in a full MSISE-00 atmosphere or gravity-wave generation by atmospheric explosions. We validate the computations by comparing them to analytical solutions based on dispersion relations in specific benchmark cases: an atmospheric explosion, and a ground displacement forcing.

  7. Multi-scale Model Coupling for CFD Simulations of Discharge Dispersion in the Sea

    Science.gov (United States)

    Robinson, D.; Wood, M.; Piggott, M. D.; Gorman, G.

    2014-12-01

    The processes that influence the dispersion of effluent discharges in the sea occur over a wide range of length and time scales. The distance that effluent can travel before it is considered mixed can be several kilometres, whereas the turbulent eddies that affect the near-field mixing of a discharge can be as small as a few centimetres. The range of scales that are involved mean that it is not generally practical to include all influencing physical phenomena within one model. Typically, the modelling of effluent dispersion is performed using two separate numerical models: a local model of the outlet(s), including the near-field effects of momentum, buoyancy and turbulence; and a larger scale model that can include the far-field effects of tidal-, wind- and wave-driven-currents, water depth variations, atmospheric fluxes, and Coriolis forces. The boundary between the two models is often not strictly defined, but is usually placed at the transition from where the behaviour of the effluent is dominated by the ambient environment, rather than the discharge characteristics and outfall configuration. In most real applications, this transition line varies considerably in time and space. This paper presents the findings of collaborative research between the Applied Modelling and Computation Group (AMCG) at Imperial College London, UK, and HR Wallingford Ltd. Results are presented using a range of coupling methods to link the near- and far-field mixing regions. An idealised domain and tidal conditions are used, with the outfall and ambient conditions typical of those found at small coastal desalination plants. Open-source CFD code Fluidity is used for both the near-field and far-field modelling. Fluidity scales well when run in parallel on large numbers of cores. It also has an anisotropic adaptive mesh capability which allows local control over solution accuracy throughout the domain. This combination means that accuracy can be achieved without excessive time costs, with

  8. Mechanistic analytical models for long-distance seed dispersal by wind.

    Science.gov (United States)

    Katul, G G; Porporato, A; Nathan, R; Siqueira, M; Soons, M B; Poggi, D; Horn, H S; Levin, S A

    2005-09-01

    We introduce an analytical model, the Wald analytical long-distance dispersal (WALD) model, for estimating dispersal kernels of wind-dispersed seeds and their escape probability from the canopy. The model is based on simplifications to well-established three-dimensional Lagrangian stochastic approaches for turbulent scalar transport resulting in a two-parameter Wald (or inverse Gaussian) distribution. Unlike commonly used phenomenological models, WALD's parameters can be estimated from the key factors affecting wind dispersal--wind statistics, seed release height, and seed terminal velocity--determined independently of dispersal data. WALD's asymptotic power-law tail has an exponent of -3/2, a limiting value verified by a meta-analysis for a wide variety of measured dispersal kernels and larger than the exponent of the bivariate Student t-test (2Dt). We tested WALD using three dispersal data sets on forest trees, heathland shrubs, and grassland forbs and compared WALD's performance with that of other analytical mechanistic models (revised versions of the tilted Gaussian Plume model and the advection-diffusion equation), revealing fairest agreement between WALD predictions and measurements. Analytical mechanistic models, such as WALD, combine the advantages of simplicity and mechanistic understanding and are valuable tools for modeling large-scale, long-term plant population dynamics. PMID:16224691

  9. Mechanistic analytical models for long-distance seed dispersal by wind.

    Science.gov (United States)

    Katul, G G; Porporato, A; Nathan, R; Siqueira, M; Soons, M B; Poggi, D; Horn, H S; Levin, S A

    2005-09-01

    We introduce an analytical model, the Wald analytical long-distance dispersal (WALD) model, for estimating dispersal kernels of wind-dispersed seeds and their escape probability from the canopy. The model is based on simplifications to well-established three-dimensional Lagrangian stochastic approaches for turbulent scalar transport resulting in a two-parameter Wald (or inverse Gaussian) distribution. Unlike commonly used phenomenological models, WALD's parameters can be estimated from the key factors affecting wind dispersal--wind statistics, seed release height, and seed terminal velocity--determined independently of dispersal data. WALD's asymptotic power-law tail has an exponent of -3/2, a limiting value verified by a meta-analysis for a wide variety of measured dispersal kernels and larger than the exponent of the bivariate Student t-test (2Dt). We tested WALD using three dispersal data sets on forest trees, heathland shrubs, and grassland forbs and compared WALD's performance with that of other analytical mechanistic models (revised versions of the tilted Gaussian Plume model and the advection-diffusion equation), revealing fairest agreement between WALD predictions and measurements. Analytical mechanistic models, such as WALD, combine the advantages of simplicity and mechanistic understanding and are valuable tools for modeling large-scale, long-term plant population dynamics.

  10. A numerical model for analysis of direct containment heating by dispersed debris

    International Nuclear Information System (INIS)

    A simple numerical model has been developed to analyze the effects of releasing molten debris into the Containment Vessel (CV) which is filled with air in certain severe reactor accident scenarios. This model predicts the time dependent heat up of a gas atmosphere resulting from the gas-driven dispersal of high temperature debris droplets. The debris deplet phase is tracked in the Lagrangian frame and the gas phase is described by using single-volume lumped parameter approach. It computes the transport of debris particles/droplets through the air in the containment by simplified debris pathway and evaluates heat exchanges between two phases. It also takes into account for the chemical reaction of the debris with the oxygen and the formation of aerosol by the vaporization of metal from the surfaces of droplets. This numerical model is used to simulate the Sandia National Laboratory (SNL) SURTSEY Direct Containment Heating tests. Computational results are compared with those obtained from experiments. It has agreements qualitatively with the experimental data

  11. Atmospheric Rivers in a Hierarchy of High-Resolution Global Atmospheric Models

    Science.gov (United States)

    Schiemann, R.; Demory, M. E.; Lavers, D. A.; Mizielinski, M.; Vidale, P. L.; Roberts, M.

    2014-12-01

    Atmospheric rivers are long and narrow plumes that carry moisture over land along frontal zones associated with mid-latitude storms. They can account for 90% of the horizontal moisture transport in a given day and are responsible for major flooding, particularly along western coastal regions (western coasts of North America and Europe). It is therefore crucial to well simulate these events in climate models in order to improve predictions and attributions of heavy precipitation and flooding along western coastal regions. In this study, we investigate the ability of a state-of-the art climate model to represent the location, frequency and structure of atmospheric rivers affecting Western Europe and California. By making use of the UPSCALE (UK on PRACE: weather resolving Simulations of Climate for globAL Environmental risk) campaign, a traceable hierarchy of global atmospheric simulations (based on the Met Office Unified Model, GA3 formulation), with mesh sizes ranging from 130 km to 25 km, we study the impact of improved representation of small-scale processes on the mean climate, its variability and extremes in order to understand the processes underlying observed improvement with higher resolution. Five-member ensembles of 27-year, atmosphere-only integrations are available at these resolutions, using both present day forcing and a future climate scenario. Demory et al (2014) have already shown that a relatively coarse resolution limits the model's ability to simulate moisture transport from ocean to land. This is particularly true at mid-latitude, where the transport is dominated by eddies. Increasing horizontal resolution increases eddy transport of moisture at mid-latitudes. Here, we investigate the climatology of atmospheric rivers, in particular their frequency and associated precipitation, compared to reanalysis products. Some aspects of the relationship between the improved simulation of moisture transport in current climate conditions, and how this impacts

  12. Influence of model resolution on the atmospheric transport of 10Be

    Directory of Open Access Journals (Sweden)

    A. M. Smith

    2012-07-01

    Full Text Available Understanding the transport path of the solar activity proxy 10Be from source to archive is crucial for the interpretation of its observed variability. The extent of mixing of the strong production signal has been quantified in a previous study (Heikkilä et al., 2009. In this study we perform sensitivity studies to investigate the influence of model resolution on the level of mixing and transport path of 10Be in the atmosphere using the ECHAM5-HAM aerosol-climate model. This study permits us to choose an acceptable resolution, and so minimum CPU time, to produce physically accurate reconstructions. Four model resolutions are applied: T21L19: a coarse horizontal and vertical resolution with model top at ca. 30 km, T42L31: an average horizontal and fine vertical one, T42L39: similar vertical resolution than L19 but including the middle atmosphere up to ca. 80 km and T63L47: a fine resolution horizontally and vertically with middle atmosphere. Comparison with observations suggests that a finer vertical resolution might be beneficial, although the spread between observations was much larger than between the four model runs. A full validation of the resolutions is not possible with the limited number of observations available. In terms of atmospheric mixing the differences became more distinguishable. All resolutions agreed that the main driver of deposition variability is the stratospheric 10Be (total contribution 68% which is transported into the troposphere at latitudes 30–50°. In the troposphere the model resolutions deviated largely in the dispersion of the stratospheric component over latitude. The finest resolution (T63L47 predicted the least dispersion towards low latitudes but the most towards the poles, whereas the coarsest resolution (T21L19 suggested the opposite. The tropospheric components of 10Be differed less between the four model runs. The largest differences were found in the polar tropospheric components, which contribute the

  13. A Shallow Layer Model for Heavy Gas Dispersion from Natural Sources: Application at Caldara di Manziana, Italy.

    Science.gov (United States)

    Chiodini, G.; Costa, A.; Hankin, R. K.; Granieri, D.; Cardellini, C.; Caliro, S.; Avino, R.

    2006-12-01

    Many volcanic and non-volcanic areas in Italy emit a very large amount of gas into the atmosphere. Several non-volcanic sources in Central Italy emit a huge amount of cold carbon dioxide (CO2). These degassing areas are generally fed by buried carbonate reservoirs, covered by low permeability formations, where the gas produced at depth accumulates before the expulsion at the surface. Under stable atmospheric conditions and/or in presence of topographic depressions, its concentration can reach high values resulting in lethal effects to humans or animals. In fact, several episodes of this phenomenon were recorded in Central Italy and in different areas. Although from a theoretical point of view, gas dispersion can be fully studied by solving the complete equations system for mass, momentum and energy transport, in actual practice, different simplified models able to describe only specific phases or aspects have to be used. In order to simulate dispersion of a heavy gas and to assess the consequent hazard we used TWODEE model based on a shallow layer approach. This technique which uses depth-averaged variables to describe the flow behavior of dense gas over complex topography represents a good compromise between the complexity of Computational Fluid Dynamics (CFD) models and the simpler integral models. Here as an application we present results for a vented CO2 release at Caldara di Manziana in Central Italy using the TWODEE model. We studied as different meteorological conditions, windspeed and topography can affect the dispersion pattern of the gas river. A comparison with the values measured during an apposite campaign is also presented. The obtained results show the potential of the applied model for hazard assessment and risk mitigation.

  14. Evaluation protocol for the WIND system atmospheric models

    Energy Technology Data Exchange (ETDEWEB)

    Fast, J.D.

    1991-12-31

    Atmospheric transport and diffusion models have been developed for real-time calculations of the location and concentration of toxic or radioactive materials during a accidental release at the Savannah River Site (SRS). These models are have been incorporated into an automated menu-driven computer based system called the WIND (Weather INformation and Display) system. In an effort to establish more formal quality assurance procedures for the WIND system atmospheric codes, a software evaluation protocol is being developed. An evaluation protocol is necessary to determine how well they may perform in emergency response (real-time) situations. The evaluation of high-impact software must be conducted in accordance with WSRC QA Manual, 1Q, QAP 20-1. This report will describe the method that will be used to evaluate the atmospheric models. The evaluation will determine the effectiveness of the atmospheric models in emergency response situations, which is not necessarily the same procedure used for research purposes. The format of the evaluation plan will provide guidance for the evaluation of atmospheric models that may be added to the WIND system in the future. The evaluation plan is designed to provide the user with information about the WIND system atmospheric models that is necessary for emergency response situations.

  15. Evaluation protocol for the WIND system atmospheric models

    Energy Technology Data Exchange (ETDEWEB)

    Fast, J.D.

    1991-01-01

    Atmospheric transport and diffusion models have been developed for real-time calculations of the location and concentration of toxic or radioactive materials during a accidental release at the Savannah River Site (SRS). These models are have been incorporated into an automated menu-driven computer based system called the WIND (Weather INformation and Display) system. In an effort to establish more formal quality assurance procedures for the WIND system atmospheric codes, a software evaluation protocol is being developed. An evaluation protocol is necessary to determine how well they may perform in emergency response (real-time) situations. The evaluation of high-impact software must be conducted in accordance with WSRC QA Manual, 1Q, QAP 20-1. This report will describe the method that will be used to evaluate the atmospheric models. The evaluation will determine the effectiveness of the atmospheric models in emergency response situations, which is not necessarily the same procedure used for research purposes. The format of the evaluation plan will provide guidance for the evaluation of atmospheric models that may be added to the WIND system in the future. The evaluation plan is designed to provide the user with information about the WIND system atmospheric models that is necessary for emergency response situations.

  16. Solitary excitations in discrete two-dimensional nonlinear Schrodinger models with dispersive dipole-dipole interactions

    DEFF Research Database (Denmark)

    Christiansen, Peter Leth; Gaididei, Yuri Borisovich; Johansson, M.;

    1998-01-01

    The dynamics of discrete two-dimensional nonlinear Schrodinger models with long-range dispersive interactions is investigated. In particular, we focus on the cases where the dispersion arises from a dipole-dipole interaction, assuming the dipole moments at each lattice site to be aligned either...

  17. Delay differential models in multimode laser dynamics: taking chromatic dispersion into account

    Science.gov (United States)

    Vladimirov, A. G.; Huyet, G.; Pimenov, A.

    2016-04-01

    A set of differential equations with distributed delay is derived for modeling of multimode ring lasers with intracavity chromatic dispersion. Analytical stability analysis of continuous wave regimes is performed and it is demonstrated that sufficiently strong anomalous dispersion can destabilize these regimes.

  18. Release and dispersion of vegetation and peat fire emissions in the atmosphere over Indonesia 1997/1998

    Directory of Open Access Journals (Sweden)

    B. Langmann

    2004-01-01

    Full Text Available Smoke-haze episodes caused by vegetation and peat fires affect parts of Indonesia every year with significant impacts on human health and climate. Particularly fires in degenerated peat areas release huge amounts of trace gases, e.g. CO2, CO and CH4, and particles into the atmosphere, exceeding by far the emissions per unit area from fires in surface vegetation. However, only limited information is available about the current distribution of pristine and degenerated peat areas in Indonesia, their depth, drainage condition and modification by fire. Particularly during the strong El Niño event in 1997/1998 a huge uncertainty exists about the contribution of Indonesian peat fire emissions to the measured increase of atmospheric CO2, as the published estimates of the peat area burned differ considerably. In this paper we study the contribution of peat fire emissions in Indonesia during the El Niño event 1997/1998. A regional three-dimensional atmosphere-chemistry model is applied over Indonesia using two emission estimates. These vegetation and peat fire emission inventories for Indonesia are set up in 0.5° resolution in weekly intervals and differ only in the size of the fire affected peat areas. We evaluate simulated rainfall and particle concentrations by comparison with observations to draw conclusions on the total carbon emissions released from the vegetation and peat fires in Indonesia in 1997/1998.

  19. Release and dispersion of vegetation and peat fire emissions in the atmosphere over Indonesia 1997/1998

    Science.gov (United States)

    Langmann, B.; Heil, A.

    2004-11-01

    Smoke-haze episodes caused by vegetation and peat fires affect parts of Indonesia every year with significant impacts on human health and climate. Particularly fires in degenerated peat areas release huge amounts of trace gases, e.g. CO2, CO and CH4, and particles into the atmosphere, exceeding by far the emissions per unit area from fires in surface vegetation. However, only limited information is available about the current distribution of pristine and degenerated peat areas in Indonesia, their depth, drainage condition and modification by fire. Particularly during the strong El Niño event in 1997/1998 a huge uncertainty exists about the contribution of Indonesian peat fire emissions to the measured increase of atmospheric CO2, as the published estimates of the peat area burned differ considerably. In this paper we study the contribution of peat fire emissions in Indonesia during the El Niño event 1997/1998. A regional three-dimensional atmosphere-chemistry model is applied over Indonesia using two emission estimates. These vegetation and peat fire emission inventories for Indonesia are set up in 0.5° resolution in weekly intervals and differ only in the size of the fire affected peat areas. We evaluate simulated rainfall and particle concentrations by comparison with observations to draw conclusions on the total carbon emissions released from the vegetation and peat fires in Indonesia in 1997/1998.

  20. Dispersal leads to spatial autocorrelation in species distributions: A simulation model

    Science.gov (United States)

    Bahn, V.; Krohn, W.B.; O'Connor, R.J.

    2008-01-01

    Compared to population growth regulated by local conditions, dispersal has been underappreciated as a central process shaping the spatial distribution of populations. This paper asks: (a) which conditions increase the importance of dispersers relative to local recruits in determining population sizes? and (b) how does dispersal influence the spatial distribution patterns of abundances among connected populations? We approached these questions with a simulation model of populations on a coupled lattice with cells of continuously varying habitat quality expressed as carrying capacities. Each cell contained a population with the basic dynamics of density-regulated growth, and was connected to other populations by immigration and emigration. The degree to which dispersal influenced the distribution of population sizes depended most strongly on the absolute amount of dispersal, and then on the potential population growth rate. Dispersal decaying in intensity with distance left close neighbours more alike in population size than distant populations, leading to an increase in spatial autocorrelation. The spatial distribution of species with low potential growth rates is more dependent on dispersal than that of species with high growth rates; therefore, distribution modelling for species with low growth rates requires particular attention to autocorrelation, and conservation management of these species requires attention to factors curtailing dispersal, such as fragmentation and dispersal barriers. ?? 2007 Elsevier B.V. All rights reserved.

  1. PCBs in the Arctic atmosphere: determining important driving forces using a global atmospheric transport model

    Directory of Open Access Journals (Sweden)

    C. L. Friedman

    2015-11-01

    Full Text Available We present a spatially and temporally resolved global atmospheric PCB model, driven by meteorological data, that is skilled at simulating mean atmospheric PCB concentrations and seasonal cycles in the Northern Hemisphere mid-latitudes, and mean Arctic concentrations. However, the model does not capture the observed Arctic summer maximum in atmospheric PCBs. We use the model to estimate global budgets for the International Council for the Exploration of the Sea 7 PCBs, and demonstrate that congeners that deposit more readily show lower potential for long-range transport, consistent with a recently-described "differential removal hypothesis" regarding the hemispheric transport of PCBs. Using sensitivity simulations to assess processes within, outside, or transport to the Arctic, we examine the influence of climate- and emissions-driven processes on Arctic concentrations and their effect on improving the simulated Arctic seasonal cycle. We find evidence that processes occurring outside the Arctic have a greater influence on Arctic atmospheric PCB levels than processes that occur within the Arctic. Our simulations suggest that re-emissions from sea ice melting or from the Arctic Ocean during summer would have to be unrealistically high in order to capture observed temporal trends of PCBs in the Arctic atmosphere. We conclude that mid-latitude processes are likely to have a greater effect on the Arctic under global change scenarios than re-emissions within the Arctic.

  2. Measuring the basic parameters of neutron stars using model atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Suleimanov, V.F. [Universitaet Tuebingen, Institut fuer Astronomie und Astrophysik, Kepler Center for Astro and Particle Physics, Tuebingen (Germany); Kazan Federal University, Kazan (Russian Federation); Poutanen, J. [University of Turku, Tuorla Observatory, Department of Physics and Astronomy, Piikkioe (Finland); KTH Royal Institute of Technology and Stockholm University, Nordita, Stockholm (Sweden); Klochkov, D.; Werner, K. [Universitaet Tuebingen, Institut fuer Astronomie und Astrophysik, Kepler Center for Astro and Particle Physics, Tuebingen (Germany)

    2016-02-15

    Model spectra of neutron star atmospheres are nowadays widely used to fit the observed thermal X-ray spectra of neutron stars. This fitting is the key element in the method of the neutron star radius determination. Here, we present the basic assumptions used for the neutron star atmosphere modeling as well as the main qualitative features of the stellar atmospheres leading to the deviations of the emergent model spectrum from blackbody. We describe the properties of two of our model atmosphere grids: i) pure carbon atmospheres for relatively cool neutron stars (1-4MK) and ii) hot atmospheres with Compton scattering taken into account. The results obtained by applying these grids to model the X-ray spectra of the central compact object in supernova remnant HESS 1731-347, and two X-ray bursting neutron stars in low-mass X-ray binaries, 4U 1724-307 and 4U 1608-52, are presented. Possible systematic uncertainties associated with the obtained neutron star radii are discussed. (orig.)

  3. Measuring the basic parameters of neutron stars using model atmospheres

    CERN Document Server

    Suleimanov, V F; Klochkov, D; Werner, K

    2015-01-01

    Model spectra of neutron star atmospheres are nowadays widely used to fit the observed thermal X-ray spectra of neutron stars. This fitting is the key element in the method of the neutronstar radius determination. Here, we present the basic assumptions used for the neutron star atmosphere modeling as well as the main qualitative features of the stellar atmospheres leading to the deviations of the emergent model spectrum from blackbody. We describe the properties of two of our model atmosphere grids: (i) pure carbon atmospheres for relatively cool neutron stars (1--4 MK) and (ii) hot atmospheres with Compton scattering taken into account. The results obtained by applying these grids to model the X-ray spectra of the central compact object in supernova remnant HESS 1731-347, and two X-ray bursting neutron stars in low-mass X-ray binaries, 4U 1724-307 and 4U 1608-52, are presented. Possible systematic uncertainties associated with the obtained neutron star radii are discussed.

  4. Information Flow in an Atmospheric Model and Data Assimilation

    Science.gov (United States)

    Yoon, Young-noh

    2011-01-01

    Weather forecasting consists of two processes, model integration and analysis (data assimilation). During the model integration, the state estimate produced by the analysis evolves to the next cycle time according to the atmospheric model to become the background estimate. The analysis then produces a new state estimate by combining the background…

  5. Atmospheric corrosion model and monitor for low cost solar arrays

    Science.gov (United States)

    Kaelble, D. H.; Mansfeld, F. B.; Jeanjaquet, S. L.; Kendig, M.

    1981-01-01

    An atmospheric corrosion model and corrosion monitoring system has been developed for low cost solar arrays (LSA). The corrosion model predicts that corrosion rate is the product of the surface condensation probability of water vapor and the diffusion controlled corrosion current. This corrosion model is verified by simultaneous monitoring of weather conditions and corrosion rates at the solar array test site at Mead, Nebraska.

  6. Observations, Thermochemical Calculations, and Modeling of Exoplanetary Atmospheres

    CERN Document Server

    Blecic, Jasmina

    2016-01-01

    This dissertation as a whole aims to provide means to better understand hot-Jupiter planets through observing, performing thermochemical calculations, and modeling their atmospheres. We used Spitzer multi-wavelength secondary-eclipse observations and targets with high signal-to-noise ratios, as their deep eclipses allow us to detect signatures of spectral features and assess planetary atmospheric structure and composition with greater certainty. Chapter 1 gives a short introduction. Chapter 2 presents the Spitzer secondary-eclipse analysis and atmospheric characterization of WASP-14b. WASP-14b is a highly irradiated, transiting hot Jupiter. By applying a Bayesian approach in the atmospheric analysis, we found an absence of thermal inversion contrary to theoretical predictions. Chapter 3 describes the infrared observations of WASP-43b Spitzer secondary eclipses, data analysis, and atmospheric characterization. WASP-43b is one of the closest-orbiting hot Jupiters, orbiting one of the coolest stars with a hot Ju...

  7. Modeling Flow around Bluff Bodies and Predicting Urban Dispersion Using Large Eddy Simulation

    OpenAIRE

    Tseng, Yu-heng; Meneveau, Charles; Parlange, Marc

    2006-01-01

    Modeling air pollutant transport and dispersion in urban environments is especially challenging due to complex ground topography. In this study, we describe a large eddy simulation (LES) tool including a new dynamic subgrid closure and boundary treatment to model urban dispersion problems. The numerical model is developed, validated, and extended to a realistic urban layout. In such applications fairly coarse grids must be used in which each building can be represented using relatively few gr...

  8. Fiscal Year 1991 summary report of NOAA Atmospheric Sciences Modeling Division support to the U.S. Environmental Protection Agency. Technical memo

    International Nuclear Information System (INIS)

    The Atmospheric Sciences Modeling Division provided meteorological research and operational support to the U.S. Environmental Protection Agency during FY-1991. Meteorological support consisted of the application of dispersion models, and the conduct of dispersion studies and model evaluations. The primary research effort was the development and evaluation of air quality simulation models using numerical and physical techniques supported by field studies. This included development of the Regional Acid Deposition Model - Version 2.6, the Tagged Species Engineering Model, and the Asymmetrical Convective Model; examination of the effect of oxidant limitations on emission changes; publication of the Regional Oxidant Model user's guides; study of the effect of biogenic emissions on ozone concentrations; incorporation of a new method describing aerosol dynamics into the Regional Particulate Model; participation in a field study of sustained stagnation conditions; conduct of a wind tunnel study of the dispersion of dense gas jets; and a study of flow and dispersion through an urban industrial complex

  9. Modified Raman Response Model and Supercontinuum Generation in Flat Dispersion Photonic Crystal Fiber with Two-Zero Dispersion Wavelengths

    Institute of Scientific and Technical Information of China (English)

    WANG He-Lin; YANG Ai-Jun; LENG Yu-Xin; WANG Cheng

    2011-01-01

    The generation mechanisms of supercontinuum(SC)and the effect of the modified Raman model on SC are further analyzed in a flat dispersion photonic crystal fiber(PCF)with two-zero dispersion wavelengths(TZDWs)by introducing an accurate Raman response function in the scalar nonlinear Scho?dinger equation.The results show that the introduction of Boson peak in the modified Raman gain model not only results in much rapider broadening of SC but also promotes more pump pulse energy transferred to the short wavelength region,which is related to stimulated Raman scattering.Moreover,SC generated from the PCF splits into two spectral bands,and their spectral peaks rapidly separate and broaden with the increase of incidcnt power.Double-band central wavelengths are finally located at about 850 nm and 1220 nm.The pumping energy depletion phenomenon occurs.The simulated results from the modified Raman model are in better agreement with the experimental results than that from the single-Lorentzian moder.

  10. A dynamic approach for the impact of a toxic gas dispersion hazard considering human behaviour and dispersion modelling.

    Science.gov (United States)

    Lovreglio, Ruggiero; Ronchi, Enrico; Maragkos, Georgios; Beji, Tarek; Merci, Bart

    2016-11-15

    The release of toxic gases due to natural/industrial accidents or terrorist attacks in populated areas can have tragic consequences. To prevent and evaluate the effects of these disasters different approaches and modelling tools have been introduced in the literature. These instruments are valuable tools for risk managers doing risk assessment of threatened areas. Despite the significant improvements in hazard assessment in case of toxic gas dispersion, these analyses do not generally include the impact of human behaviour and people movement during emergencies. This work aims at providing an approach which considers both modelling of gas dispersion and evacuation movement in order to improve the accuracy of risk assessment for disasters involving toxic gases. The approach is applied to a hypothetical scenario including a ship releasing Nitrogen dioxide (NO2) on a crowd attending a music festival. The difference between the results obtained with existing static methods (people do not move) and a dynamic approach (people move away from the danger) which considers people movement with different degrees of sophistication (either a simple linear path or more complex behavioural modelling) is discussed. PMID:27343142

  11. High Resolution Global Modeling of the Atmospheric Circulation

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    An informal review is presented of recent developments in numerical simulation of the global atmospheric circulation with very fine numerical resolution models. The focus is on results obtained recently with versions of the GFDL SKYHI model and the Atmospheric Model for the Earth Simulator (AFES) global atmospheric models. These models have been run with effective horizontal grid resolution of ~10-40 km and fine vertical resolution. The results presented demonstrate the utility of such models for the study of a diverse range of phenomena. Specifically the models are shown to simulate the development of tropical cyclones with peak winds and minimum central pressures comparable to those of the most intense hurricanes actually observed. More fundamentally, the spectrum of energy content in the mesoscale in the flow can be reproduced by these models down to near the smallest explicitly-resolved horizontal scales. In the middle atmosphere it is shown that increasing horizontal resolution can lead to significantly improved overall simulation of the global-scale circulation. The application of the models to two specific problems requiring very fine resolution global will be discussed. The spatial and temporal variability of the vertical eddy flux of zonal momentum associated with gravity waves near the tropopause is evaluated in the very fine resolution AFES model. This is a subject of great importance for understanding and modelling the flow in the middle atmosphere. Then the simulation of the small scale variations of the semidiurnal surface pressure oscillation is analyzed, and the signature of significant topographic modulation of the semidiurnal atmospheric tide is identified.

  12. Regional atmospheric budgets of reduced nitrogen over the British isles assessed using a multi-layer atmospheric transport model

    NARCIS (Netherlands)

    Fournier, N.; Tang, Y.S.; Dragosits, U.; Kluizenaar, Y.de; Sutton, M.A.

    2005-01-01

    Atmospheric budgets of reduced nitrogen for the major political regions of the British Isles are investigated with a multi-layer atmospheric transport model. The model is validated against measurements of NH3 concentration and is developed to provide atmospheric budgets for defined subdomains of the

  13. Examining Tatooine: Atmospheric Models of Neptune-Like Circumbinary Planets

    CERN Document Server

    May, E M

    2016-01-01

    Circumbinary planets experience a time varying irradiation pattern as they orbit their two host stars. In this work, we present the first detailed study of the atmospheric effects of this irradiation pattern on known and hypothetical gaseous circumbinary planets. Using both a one-dimensional Energy Balance Model and a three-dimensional General Circulation Model, we look at the temperature differences between circumbinary planets and their equivalent single-star cases in order to determine the nature of the atmospheres of these planets. We find that for circumbinary planets on stable orbits around their host stars, temperature differences are on average no more than 1.0% in the most extreme cases. Based on detailed modeling with the General Circulation Model, we find that these temperature differences are not large enough to excite circulation differences between the two cases. We conclude that gaseous circumbinary planets can be treated as their equivalent single-star case in future atmospheric modeling effor...

  14. CFD Modeling of Non-Neutral Atmospheric Boundary Layer Conditions

    DEFF Research Database (Denmark)

    Koblitz, Tilman

    For wind resource assessment, the wind industry is increasingly relying on Computational Fluid Dynamics models that focus on modeling the airflow in a neutrally stratified surface-layer. Physical processes like the Coriolis force, buoyancy forces and heat transport, that are important to the atmo......For wind resource assessment, the wind industry is increasingly relying on Computational Fluid Dynamics models that focus on modeling the airflow in a neutrally stratified surface-layer. Physical processes like the Coriolis force, buoyancy forces and heat transport, that are important...... to the atmospheric boundary-layer, are mostly ignored so far. In order to decrease the uncertainty of wind resource assessment, the present work focuses on atmospheric flows that include atmospheric stability and the Coriolis effect. Within the present work a RANS model framework is developed and implemented...

  15. Regional forecasting with global atmospheric models; Fourth year report

    Energy Technology Data Exchange (ETDEWEB)

    Crowley, T.J.; North, G.R.; Smith, N.R. [Applied Research Corp., College Station, TX (United States)

    1994-05-01

    The scope of the report is to present the results of the fourth year`s work on the atmospheric modeling part of the global climate studies task. The development testing of computer models and initial results are discussed. The appendices contain studies that provide supporting information and guidance to the modeling work and further details on computer model development. Complete documentation of the models, including user information, will be prepared under separate reports and manuals.

  16. The physical theory and propagation model of THz atmospheric propagation

    Science.gov (United States)

    Wang, R.; Yao, J. Q.; Xu, D. G.; Wang, J. L.; Wang, P.

    2011-02-01

    Terahertz (THz) radiation is extensively applied in diverse fields, such as space communication, Earth environment observation, atmosphere science, remote sensing and so on. And the research on propagation features of THz wave in the atmosphere becomes more and more important. This paper firstly illuminates the advantages and outlook of THz in space technology. Then it introduces the theoretical framework of THz atmospheric propagation, including some fundamental physical concepts and processes. The attenuation effect (especially the absorption of water vapor), the scattering of aerosol particles and the effect of turbulent flow mainly influence THz atmosphere propagation. Fundamental physical laws are illuminated as well, such as Lamber-beer law, Mie scattering theory and radiative transfer equation. The last part comprises the demonstration and comparison of THz atmosphere propagation models like Moliere(V5), SARTre and AMATERASU. The essential problems are the deep analysis of physical mechanism of this process, the construction of atmospheric propagation model and databases of every kind of material in the atmosphere, and the standardization of measurement procedures.

  17. On atmospheric stability in the dynamic wake meandering model

    DEFF Research Database (Denmark)

    Keck, Rolf-Erik; de Mare, Martin Tobias; Churchfield, Matthew J.;

    2014-01-01

    The present study investigates a new approach for capturing the effects of atmospheric stability on wind turbine wake evolution and wake meandering by using the dynamic wake meandering model. The most notable impact of atmospheric stability on the wind is the changes in length and velocity scales...... with an actuator line model and field measurements, where generally good agreement is found with respect to the velocity, turbulence intensity and power predictions. Copyright © 2013 John Wiley & Sons, Ltd....... parameters. In order to isolate the effect of atmospheric stability, simulations of neutral and unstable atmospheric boundary layers using large-eddy simulation are performed at the same streamwise turbulence intensity level. The turbulence intensity is kept constant by calibrating the surface roughness...

  18. Key features of the IPSL ocean atmosphere model and its sensitivity to atmospheric resolution

    Energy Technology Data Exchange (ETDEWEB)

    Marti, Olivier; Braconnot, P.; Bellier, J.; Brockmann, P.; Caubel, A.; Noblet, N. de; Friedlingstein, P.; Idelkadi, A.; Kageyama, M. [Unite Mixte CEA-CNRS-UVSQ, IPSL/LSCE, Gif-sur-Yvette Cedex (France); Dufresne, J.L.; Bony, S.; Codron, F.; Fairhead, L.; Grandpeix, J.Y.; Hourdin, F.; Musat, I. [Unite Mixte CNRS-Ecole Polytechnique-ENS-UPCM, IPSL/LMD, Paris Cedex 05 (France); Benshila, R.; Guilyardi, E.; Levy, C.; Madec, G.; Mignot, J.; Talandier, C. [unite mixte CNRS-IRD-UPMC, IPLS/LOCEAN, Paris Cedex 05 (France); Cadule, P.; Denvil, S.; Foujols, M.A. [Institut Pierre Simon Laplace des Sciences de l' Environnement (IPSL), Paris Cedex 05 (France); Fichefet, T.; Goosse, H. [Universite Catholique de Louvain, Institut d' Astronomie et de Geophysique Georges Lemaitre, Louvain-la-Neuve (Belgium); Krinner, G. [Unite mixte CNRS-UJF Grenoble, LGGE, BP96, Saint-Martin-d' Heres (France); Swingedouw, D. [CNRS/CERFACS, Toulouse (France)

    2010-01-15

    This paper presents the major characteristics of the Institut Pierre Simon Laplace (IPSL) coupled ocean-atmosphere general circulation model. The model components and the coupling methodology are described, as well as the main characteristics of the climatology and interannual variability. The model results of the standard version used for IPCC climate projections, and for intercomparison projects like the Paleoclimate Modeling Intercomparison Project (PMIP 2) are compared to those with a higher resolution in the atmosphere. A focus on the North Atlantic and on the tropics is used to address the impact of the atmosphere resolution on processes and feedbacks. In the North Atlantic, the resolution change leads to an improved representation of the storm-tracks and the North Atlantic oscillation. The better representation of the wind structure increases the northward salt transports, the deep-water formation and the Atlantic meridional overturning circulation. In the tropics, the ocean-atmosphere dynamical coupling, or Bjerknes feedback, improves with the resolution. The amplitude of ENSO (El Nino-Southern oscillation) consequently increases, as the damping processes are left unchanged. (orig.)

  19. Modelling drivers of mangrove propagule dispersal and restoration of abandoned shrimp farms

    Directory of Open Access Journals (Sweden)

    D. Di Nitto

    2013-01-01

    Full Text Available Propagule dispersal of four mangrove species Rhizophora mucronata, R. apiculata, Ceriops tagal and Avicennia officinalis in the Pambala-Chilaw Lagoon Complex (Sri Lanka was studied by combining a hydrodynamic model with species-specific knowledge on propagule dispersal behaviour. Propagule transport was simulated using a finite-volume advection-diffusion model to investigate the effect of dispersal vectors (tidal flow, freshwater discharge and wind, trapping agents (retention by vegetation and seed characteristics (buoyancy on propagule dispersal patterns. Sensitivity analysis showed that smaller propagules, like the oval-shaped propagules of Avicennia officinalis, dispersed over larger distances and were most sensitive to changing values of retention by mangrove vegetation compared to larger, torpedo-shaped propagules of Rhizophora spp. and C. tagal. Directional propagule dispersal in this semi-enclosed lagoon with a small tidal range was strongly concentrated towards the edges of the lagoon and channels. Short distance dispersal appeared to be the main dispersal strategy for all four studied species, with most of the propagules being retained within the vegetation. Only a small proportion (max. 5% of propagules left the lagoon through a channel connecting the lagoon with the open sea. Wind significantly influenced dispersal distance and direction once propagules entered the lagoon or adjacent channels. Implications of these findings for mangrove restoration were tested by simulating partial removal in the model of dikes around abandoned shrimp ponds to restore tidal hydrology and facilitate natural recolonisation by mangroves. The specific location of dike removal, (with respect to the vicinity of mangroves and independently suitable hydrodynamic flows, was found to significantly affect the resultant quantities and species of inflowing of propagules and hence the potential effectiveness of natural

  20. Modelling drivers of mangrove propagule dispersal and restoration of abandoned shrimp farms

    Directory of Open Access Journals (Sweden)

    D. Di Nitto

    2013-07-01

    Full Text Available Propagule dispersal of four mangrove species Rhizophora mucronata, R. apiculata, Ceriops tagal and Avicennia officinalis in the Pambala–Chilaw Lagoon Complex (Sri Lanka was studied by combining a hydrodynamic model with species-specific knowledge on propagule dispersal behaviour. Propagule transport was simulated using a finite-volume advection-diffusion model to investigate the effect of dispersal vectors (tidal flow, freshwater discharge and wind, trapping agents (retention by vegetation and seed characteristics (buoyancy on propagule dispersal patterns. Sensitivity analysis showed that smaller propagules, like the oval-shaped propagules of Avicennia officinalis, dispersed over larger distances and were most sensitive to changing values of retention by mangrove vegetation compared to larger, torpedo-shaped propagules of Rhizophora spp. and C. tagal. Directional propagule dispersal in this semi-enclosed lagoon with a small tidal range was strongly concentrated towards the edges of the lagoon and channels. Short distance dispersal appeared to be the main dispersal strategy for all four studied species, with most of the propagules being retained within the vegetation. Only a small proportion (max. 5% of propagules left the lagoon through a channel connecting the lagoon with the open sea. Wind significantly influenced dispersal distance and direction once propagules entered the lagoon or adjacent channels. Implications of these findings for mangrove restoration were tested by simulating partial removal in the model of dikes around abandoned shrimp ponds to restore tidal hydrology and facilitate natural recolonisation by mangroves. The specific location of dike removal, (with respect to the vicinity of mangroves and independently suitable hydrodynamic flows, was found to significantly affect the resultant quantities and species of inflowing propagules and hence the potential effectiveness of natural regeneration. These results demonstrate the

  1. Atmospheric Turbulence Modeling for Aerospace Vehicles: Fractional Order Fit

    Science.gov (United States)

    Kopasakis, George (Inventor)

    2015-01-01

    An improved model for simulating atmospheric disturbances is disclosed. A scale Kolmogorov spectral may be scaled to convert the Kolmogorov spectral into a finite energy von Karman spectral and a fractional order pole-zero transfer function (TF) may be derived from the von Karman spectral. Fractional order atmospheric turbulence may be approximated with an integer order pole-zero TF fit, and the approximation may be stored in memory.

  2. Medicanes in an ocean–atmosphere coupled regional climate model

    Directory of Open Access Journals (Sweden)

    N. Akhtar

    2014-03-01

    Full Text Available So-called medicanes (Mediterranean hurricanes are meso-scale, marine, and warm-core Mediterranean cyclones that exhibit some similarities to tropical cyclones. The strong cyclonic winds associated with medicanes threaten the highly populated coastal areas around the Mediterranean basin. To reduce the risk of casualties and overall negative impacts, it is important to improve the understanding of medicanes with the use of numerical models. In this study, we employ an atmospheric limited-area model (COSMO-CLM coupled with a one-dimensional ocean model (1-D NEMO-MED12 to simulate medicanes. The aim of this study is to assess the robustness of the coupled model in simulating these extreme events. For this purpose, 11 historical medicane events are simulated using the atmosphere-only model, COSMO-CLM, and coupled model, with different setups (horizontal atmospheric grid-spacings of 0.44°, 0.22°, and 0.08°; with/without spectral nudging, and an ocean grid-spacing of 1/12°. The results show that at high-resolution, the coupled model is able to not only simulate most of medicane events but also improve the track length, core temperature, and wind speed of simulated medicanes compared to the atmosphere-only simulations. The results suggest that the coupled model is more proficient for systemic and detailed studies of historical medicane events, and that this model can be an effective tool for future projections.

  3. The Role of Atmospheric Measurements in Wind Power Statistical Models

    Science.gov (United States)

    Wharton, S.; Bulaevskaya, V.; Irons, Z.; Newman, J. F.; Clifton, A.

    2015-12-01

    The simplest wind power generation curves model power only as a function of the wind speed at turbine hub-height. While the latter is an essential predictor of power output, it is widely accepted that wind speed information in other parts of the vertical profile, as well as additional atmospheric variables including atmospheric stability, wind veer, and hub-height turbulence are also important factors. The goal of this work is to determine the gain in predictive ability afforded by adding additional atmospheric measurements to the power prediction model. In particular, we are interested in quantifying any gain in predictive ability afforded by measurements taken from a laser detection and ranging (lidar) instrument, as lidar provides high spatial and temporal resolution measurements of wind speed and direction at 10 or more levels throughout the rotor-disk and at heights well above. Co-located lidar and meteorological tower data as well as SCADA power data from a wind farm in Northern Oklahoma will be used to train a set of statistical models. In practice, most wind farms continue to rely on atmospheric measurements taken from less expensive, in situ instruments mounted on meteorological towers to assess turbine power response to a changing atmospheric environment. Here, we compare a large suite of atmospheric variables derived from tower measurements to those taken from lidar to determine if remote sensing devices add any competitive advantage over tower measurements alone to predict turbine power response.

  4. Analysis of air pollution from swine production by using air dispersion model and GIS in Quebec.

    Science.gov (United States)

    Sarr, Joachim H; Goïta, Kalifa; Desmarais, Camille

    2010-01-01

    Swine production, the second most important contributor to Quebec's agricultural revenue, faces many problems. Intensive piggeries, with up to 599 animal units, are used to raise finishing pigs for slaughter. Among the great number of gaseous species emitted to the atmospheric environment from livestock buildings and manure storage units is NH3, which is one of the most important and most offensive with respect to human health. Under appropriate meteorological and topographical conditions, gaseous contaminants can spread and cause a public nuisance--up to a 1-km radius around the farm. To mitigate these effects, the Quebec Government adopted regulations that set minimum buffer distances to be observed by any expansion of an existing or new pig farm. The objectives of this study were (i) to assess the efficiency of the current buffer distance prescriptions in Quebec in mitigating effects of air pollution from swine units and (ii) to identify potential areas for establishing pig farm operations that will not be offensive to people. The air dispersion American Meteorological Society/Environmental Protection Agency Regulatory Model (AERMOD) with receptors distributed at 1.6 km around each source was used first, followed by a spatial geographic information system (GIS) model. Results from the dispersion model showed that the highest hourly concentration with a 99.5% compliance frequency for a single farm was 3078.1 microg/m3 and exceeded the NH3 odor criterion hourly standard set by the Quebec Government at 183.4 microg/m3. Thus, for public safety, densely populated areas like housing developments must be located >1300 m from a pig farm. This distance is in the range of setback distances (723 to 1447 m) obtained by using abacuses defined in the L'Erable Regional County Municipality. That is why we can say the current rules established by the Quebec Government, if rigorously applied, can prevent odor nuisance, due to NH3 emission, from swine farms. In the spatial model

  5. Examining Tatooine: Atmospheric Models of Neptune-like Circumbinary Planets

    Science.gov (United States)

    May, E. M.; Rauscher, E.

    2016-08-01

    Circumbinary planets experience a time-varying irradiation pattern as they orbit their two host stars. In this work, we present the first detailed study of the atmospheric effects of this irradiation pattern on known and hypothetical gaseous circumbinary planets. Using both a one-dimensional energy balance model (EBM) and a three-dimensional general circulation model (GCM), we look at the temperature differences between circumbinary planets and their equivalent single-star cases in order to determine the nature of the atmospheres of these planets. We find that for circumbinary planets on stable orbits around their host stars, temperature differences are on average no more than 1.0% in the most extreme cases. Based on detailed modeling with the GCM, we find that these temperature differences are not large enough to excite circulation differences between the two cases. We conclude that gaseous circumbinary planets can be treated as their equivalent single-star case in future atmospheric modeling efforts.

  6. Dispersion processes in coastal waters - Some outstanding practical issues for monitoring and modelling

    Digital Repository Service at National Institute of Oceanography (India)

    Swamy, G.N.

    This paper highlights on the issues of dispersion processes in coastal waters like space-time description of field parameters, limitation of physical models, limitations of numerical formulations, Eulerian-Lagrangian transformations, shear...

  7. Mechanical model to evaluate the effect of the dispersion in nanocomposites

    International Nuclear Information System (INIS)

    A key parameter in taking advantage of the exceptional mechanical and physical properties of carbon nanotubes (CNT) is getting a homogeneous dispersion of the nanofiller in the matrix. Micromechanical models are used to predict the properties of composites, but in most cases the calculated results are not comparable with those from experimentation. In the case of epoxy matrices, poorly dispersed CNT are obtained, as has been observed by scanning electron microscopy. The influence of the dispersion in nanocomposite stiffness is estimated developing a new micromechanical model. Several micromechanical models and experimental results are compared with this new model, showing that the latter has better agreement with mechanical tests. In addition, this mathematical formulation could be used with other reinforcements that are poorly dispersed, not only with CNT

  8. A linear dispersion relation for the hybrid kinetic-ion/fluid-electron model of plasma physics

    CERN Document Server

    Told, Daniel; Astfalk, Patrick; Jenko, Frank

    2016-01-01

    A dispersion relation for a commonly used hybrid model of plasma physics is developed, which combines fully kinetic ions and a massless-electron fluid description. Although this model and variations of it have been used to describe plasma phenomena for about 40 years, to date there exists no general dispersion relation to describe the linear wave physics contained in the model. Previous efforts along these lines are extended here to retain arbitrary wave propagation angles, temperature anisotropy effects, as well as additional terms in the generalized Ohm's law which determines the electric field. A numerical solver for the dispersion relation is developed, and linear wave physics is benchmarked against solutions of a full Vlasov-Maxwell dispersion relation solver. This work opens the door to a more accurate interpretation of existing and future wave and turbulence simulations using this type of hybrid model.

  9. A linear dispersion relation for the hybrid kinetic-ion/fluid-electron model of plasma physics

    Science.gov (United States)

    Told, D.; Cookmeyer, J.; Astfalk, P.; Jenko, F.

    2016-07-01

    A dispersion relation for a commonly used hybrid model of plasma physics is developed, which combines fully kinetic ions and a massless-electron fluid description. Although this model and variations of it have been used to describe plasma phenomena for about 40 years, to date there exists no general dispersion relation to describe the linear wave physics contained in the model. Previous efforts along these lines are extended here to retain arbitrary wave propagation angles, temperature anisotropy effects, as well as additional terms in the generalized Ohm’s law which determines the electric field. A numerical solver for the dispersion relation is developed, and linear wave physics is benchmarked against solutions of a full Vlasov–Maxwell dispersion relation solver. This work opens the door to a more accurate interpretation of existing and future wave and turbulence simulations using this type of hybrid model.

  10. Ship plume dispersion rates in convective boundary layers for chemistry models

    Directory of Open Access Journals (Sweden)

    F. Chosson

    2008-04-01

    Full Text Available Detailed ship plume simulations in various convective boundary layer situations have been performed using a Lagrangian Dispersion Model driven by a Large Eddy Simulation Model. The simulations focus on early stage (1–2 h of plume dispersion regime and take into account the effects of plume rise on dispersion. Results are presented in an attempt to provide to chemical modellers community a realistic description of the impact of characteristic dispersion on exhaust ship plume chemistry. Plume dispersion simulations are used to derive analytical dilution rate functions. Even though results exhibit striking effects of plume rise parameter on dispersion patterns, it is shown that initial buoyancy fluxes at ship stack have minor effect on plume dilution rate. After initial high dispersion regimes a simple characteristic dilution time scale can be used to parameterize the subgrid plume dilution effects in large scale chemistry models. The results show that this parameter is directly related to the typical turn-over time scale of the convective boundary layer.

  11. A global coupled Eulerian-Lagrangian model and 1 1 km CO2 surface flux dataset for high-resolution atmospheric CO2 transport simulations

    Energy Technology Data Exchange (ETDEWEB)

    Ganshin, A [Central Aerological Observatory; Oda, T [National Institute for Environmental Studies, Japan; Saito, M [National Institute for Environmental Studies, Japan; Maksyutov, S [National Institute for Environmental Studies, Japan; Valsala, V [National Institute for Environmental Studies, Japan; Andres, Robert Joseph [ORNL; Fischer, R [University of London; Lowry, D [University of London; Lukyanov, A [Central Aerological Observatory; Matsueda, H [Meteorological Research Institute, Japan; Nisbet, E [University of London; Rigby, M [University of Bristol, UK; Sawa, Y [Meteorological Research Institute, Japan; Toumi, R [Imperial College, London; Tsuboi, K [Meteorological Research Institute, Japan; Varlagin, A [A.N. Severtsov Institute of Ecology and Evolution, Russia; Zhuravlev, R [Central Aerological Observatory

    2012-01-01

    Abstract. We designed a method to simulate atmospheric CO2 concentrations at several continuous observation sites around the globe using surface fluxes at a very high spatial resolution. The simulations presented in this study were performed using the Global Eulerian-Lagrangian Coupled Atmospheric model (GELCA), comprising a Lagrangian particle dispersion model coupled to a global atmospheric tracer transport model with presc