air dispersion model Articles
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Experimental study of turbulence and vertical temperature profile in the urban boundary layer
We observed the turbulence and vertical profile of temperature in and above the roughness sublayer (RS) using a tower, a tethered balloon and a Doppler sodar in Himeji City. A 3–D ultrasonic anemometer–thermometer was sited at a height of 54 m on the tower. The present results showed that in the RS, the ratio of friction velocity to wind speed, u* /u, observed under unstable conditions of −4.2 ...
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Urban vulnerabilities: think simple
Noting the signals coming from the community of complex critical infrastructures management indicating, on the one hand, a definite preoccupation with identifying and properly characterising system vulnerabilities and, on the other hand, a dissatisfaction with (generally) expert capabilities to provide the effective ways and means sought, this paper submits that contributing to the situation is ...
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New Nitrogen Dioxide Ambient Air Quality Standard Could Pose Challenges
In the more than 200 air quality modeling analyses that ALL4 meteorologists have conducted, demonstrating compliance with the annual nitrogen dioxide (NO2) National Ambient Air Quality Standard (NAAQS) of 53 parts per billion (ppbv) has rarely been an issue. The relative ease for demonstrating compliance with the annual NO2 NAAQS is due to two (2) factors. First, the NAAQS for NO2 is an annual ...
By All4 Inc.
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Surface energy balance: analysis of the parameterisation of the ground heat flux
The parameterisation of the surface energy balance in short-range dispersion models is currently receiving increased attention. Most of the current treatments rely on adaptations of the original schemes of Van Ulden and Holtslag, and Berkovicz and Prahm. These parameterisations are based on conventional meteorological network measurements of e.g. wind, temperature and humidity. The ground heat ...
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A congestion sensitive approach to modelling road networks for air quality management
This research establishes an approach to modelling a congested road network for air quality management, which enables the assessment of traffic management solutions that may create only subtle changes in the traffic flow regimes. Road network emissions have been calculated using standard factors taking into account details of vehicle fleet composition, average speeds and road type. Additionally, ...
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Urban boundary layer simulations of sea-breeze over Marseille during the ESCOMPTE experiment
Numerical simulations of the urban atmosphere of Marseille during the UBL/ESCOMPTE experiment that took place in June?July 2001 are presented. The atmospheric model is the SUBMESO version with grid-nesting, coupled to the urban soil model SM2U, with new parameterisations for sea surface and lateral boundary forcing. Urban characteristics are reproduced with a high degree of realism through a ...
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Diurnal variation of the mixing-layer height and polonium concentration in the air
The Mixing Height (MH) is one of the most important parameters that characterise the range of the atmospheric turbulence. This parameter shows characteristic diurnal variation but cannot be measured immediately. Therefore, it is evaluated indirectly by measuring other quantities. The measurement of radon concentration in the atmospheric air is one of the methods using natural occurring ...
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A comparative analysis of different conventional and non–local stable/neutral PBL regimes and their parameterisation in air pollution problems
The basic dynamic and diffusion characteristics in several types stable/neutral PBL turbulent regimes are determined on the basis of applied oriented complex method, which accounts for the influence of free–flow stability effects is demonstrated. In particular the results can be used for parameterisation of dynamic and diffusion processes in PBL under such conditions.Keywords: non–local stable ...
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A new model validation database for evaluating AERMOD, NRPB R91 and ADMS using krypton-85 data from BNFL Sellafield
The radioisotope krypton-85 (85Kr) is emitted into the atmosphere from nuclear fuel reprocessing plant. Releases from the BNFL Sellafield complex have been used to evaluate the performance of regulatory atmospheric dispersion models. Field measurements of 85Kr, associated emissions and meteorological data and dispersion model predictions have been collated into a model validation database that ...
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Air Dispersion Models - Models can be used to aid in demonstrating environmental compliance, analyzing process changes and evaluating the impacts of accidental releases
Air dispersion models are used to estimate the downwind concentration of pollutants emitted by various pollution sources such as industrial facilities and regional public traffic. Dispersion models play an important role in the industrial and regulatory communities. They are typically used to demonstrate compliance with National Ambient Air Quality Standards as part of new source review, ...
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Computational modelling of airflow in urban street canyon and comparison with measurements
The main goal of this study was to predict the airflow in a street canyon surrounded by an urban area using CFD modelling. In the street geometry described in the main part, the actual airflow directly influences air infiltration into buildings. Different models of turbulence were tested as well as specific wind boundary conditions. A correct assignment of boundary conditions (i.e., mainly wind ...
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AERMOD View - Debug Output Files
When conducting an air dispersion modeling analysis with the AERMOD modeling system, modelers may encounter situations where they want to validate or verify the model’s calculations. To support this, the model has the ability to generate Debugging Output Files of intermediate calculation results. This is controlled by the Control Pathway using the DEBUGOPT model keyword. As the ...
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The European long-range tracer experiment, ETEX: a database for comparing model results and for harmonisation purposes
This report presents the layout and a summary of preliminary results of the European tracer experiment (ETEX), which was devised to serve several purposes, one of which was to create a database for long-range modelling.Keywords: long-, range tracers, atmospheric transport, tracer experiments, atmospheric dispersion models, air pollution, environmental pollution, ...
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Studying street geometry influence in PM10 concentration
This paper intends to show the influence of street geometry in particle concentration emitted from traffic source, on a busy street of Barreiro City, Portugal. FLUENT software was used to simulate particle dispersion, air flow and turbulence in the street. Buildings and road characteristics were considered, as well as winter and summer most predominant meteorological conditions. Also, particle ...
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Local mass transfer coefficients over idealised two–dimensional urban street canyons
In view of the large number of urban inhabitants, ventilation and pollutant transport in urban areas are major research problems for several decades. This paper focuses on the studies of the correlation between the ventilation and pollutant removal over idealised two–dimensional urban street canyons using wind tunnel experiments in the Department of Mechanical Engineering, The University of Hong ...
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Source reconstruction: a statistical mechanics perspective
A Bayesian inference scheme is used to address the problem of general source reconstruction. To this purpose, starting from a simple, physically motivated structure–based representation for a general source distribution, Bayesian probability theory is used to formulate the full joint posterior probability density function for the parameters in this representation. The exploration of the ...
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Validation of the Eulerian pollution transport model PolTran on the Kincaid data set
The study represents the first performance of the model PolTran on the Kincaid data set. PolTran is a typical representative of the Eulerian models: two dimensional Eulerian advection scheme and numerical calculation of the vertical diffusion. The meteorological pre-processor uses the Kincaid measurements of wind and temperature at 10, 50 and 100 m and provides the dispersion model with wind and ...
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A review of evaluation procedures for atmospheric dispersion models
Evaluation of atmospheric dispersion models is vital to justify their use within the air quality component of environmental assessments. The Model Validation Kit, compiled and distributed by Helge Olesen of NERI, is often used for such evaluations. Whilst the Model Validation Kit has a wide range of functionality, its users often limit their evaluation to a few simplistic calculations. ...
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The Netherlands National Model for short-range dispersion of air pollutants
The tool for dispersion calculations in The Netherlands originated from a consensus process among experts from licensing authorities, industry and science. This paper describes its characteristics and applications in the light of its history and future.Keywords: air pollution, consensus, atmospheric dispersion model, frequency distribution, Netherlands National Model, short range dispersion, ...
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A Test Reference Year (TRY) approach to gas dispersion in the atmosphere
For environmental analysis such as the dispersion of pollutants in the atmosphere, it is essential to have meteorological data that are relevant for a long period. In this paper, we explore the possibility of using an environmental Test Reference Year (TRY), i.e., a set of real, contemporaneous and hourly meteorological variables, 'extracted' from a hourly series of at least 10 years, for ...
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