- Consiglio Nazionale delle Ricerche (CNR), ISAC, Department Memberadd
The aim of this paper is to analyse the thermal effects in a wind tunnel experiment to simulate the planetary boundary layer (PBL). Experiments were performed in the wind tunnel of the Laboratory of Constructions Aerodynamics at the... more
The aim of this paper is to analyse the thermal effects in a wind tunnel experiment to simulate the planetary boundary layer (PBL). Experiments were performed in the wind tunnel of the Laboratory of Constructions Aerodynamics at the Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul State, Brazil. This wind tunnel is a closed return low-speed wind tunnel specifically designed for dynamic and static studies on civil construction models. As a novelty, one of the experimental sections of the wind tunnel was equipped with a metal sheet with Peltier elements coupled to it. In other words, thermal effects generating new flow patterns become feasible and open pathways to compare wind tunnel simulations to those in the PBL. Furthermore, measurements obtained with the smooth floor of the wind tunnel were repeated under the same conditions with the addition of the roughness in the floor, and the mechanical turbulence generated by the surface roughness significantly ampli...
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Considering the influence of the downslope windstorm called “Vento Norte” (VNOR; Portuguese for “North Wind”) in planetary boundary layer turbulent features, a new set of turbulent parameterizations, which are to be used in atmospheric... more
Considering the influence of the downslope windstorm called “Vento Norte” (VNOR; Portuguese for “North Wind”) in planetary boundary layer turbulent features, a new set of turbulent parameterizations, which are to be used in atmospheric dispersion models, has been derived. Taylor’s statistical diffusion theory, velocity spectra obtained at four levels (3, 6, 14, and 30 m) in a micrometeorological tower, and the energy-containing eddy scales are used to calculate neutral planetary boundary layer turbulent parameters. Vertical profile formulations of the wind velocity variances and Lagrangian decorrelation time scales are proposed, and to validate this new parameterization, it is applied in a Lagrangian Stochastic Particle Dispersion Model to simulate the Prairie Grass concentration experiments. The simulated concentration results were shown to agree with those observed.
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An analytical air quality dispersion model based on a discretization of the Planetary Boundary Layer in N sub-layers is presented. In each sub-layer the diffusion-advection equation is solved by the Laplace Transform techniques,... more
An analytical air quality dispersion model based on a discretization of the Planetary Boundary Layer in N sub-layers is presented. In each sub-layer the diffusion-advection equation is solved by the Laplace Transform techniques, considering an average value for the vertical exchange coefficient and the wind speed. This approach allows us to conjugate the advantages of the dispersion models based on analytical solutions and the more realistic wind and eddy diffusivity profiles related to a progress in the understanding of the Planetary Boundary Layer structure. The model's performances have been evaluated using the well-known Copenhagen dataset as well as the analytical model evaluating ground level concentrations from elevated sources (Tirabassi and Rizza, 1994). Then, the application of the statistical evaluation procedure (Hanna, 1989) over the outcoming results has shown that the proposed analytical dispersion model produces a good fitting of the observational data.
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Abstract A new puff model is presented where the 3-dimensional puff diffusion is described by an analytical solution of the atmospheric diffusion equation. Resumo Apresentamos um novo modelo tridimensional a puff onde a difusão é descrita... more
Abstract A new puff model is presented where the 3-dimensional puff diffusion is described by an analytical solution of the atmospheric diffusion equation. Resumo Apresentamos um novo modelo tridimensional a puff onde a difusão é descrita por solução analítica da equação de difusão na atmosfera.
Abstract Aeolian dust from arid and semi-arid areas contributes significantly to the global atmospheric aerosol mass and is expected to impact the climate system by direct and indirect effects. The project Saharan Mineral dust experiment... more
Abstract Aeolian dust from arid and semi-arid areas contributes significantly to the global atmospheric aerosol mass and is expected to impact the climate system by direct and indirect effects. The project Saharan Mineral dust experiment (SAMUM) aims at ...
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The recording of air pollution concentration values involves the measurement of a large volume of data. Generally, automatic selectors and explicators are provided by statistics. The use of the Representative Day allows the compilation of... more
The recording of air pollution concentration values involves the measurement of a large volume of data. Generally, automatic selectors and explicators are provided by statistics. The use of the Representative Day allows the compilation of large amounts of data in a compact format that will supply meaningful information on the whole data set. The Representative Day (RD) is a real day that best represents (in the meaning of the least squares technique) the set of daily trends of the considered time series. The Least Representative Day (LRD), on the contrary, it is a real day that worst represents (in the meaning of the least squares technique) the set of daily trends of the same time series. The identification of RD and LRD can prove to be a very important tool for identifying both anomalous and standard behaviors of pollutants within the selected period and establishing measures of prevention, limitation and control. Two application examples, in two different areas, are presented rel...
Most of the air quality dispersion models used for regulatory applications are based on K-diffusion formulations. In this paper, two turbulent parameterisations for dispersion models in the atmo spheric boundary layer are evaluated with... more
Most of the air quality dispersion models used for regulatory applications are based on K-diffusion formulations. In this paper, two turbulent parameterisations for dispersion models in the atmo spheric boundary layer are evaluated with experimental data. The first scheme is based on a similarity approach and provides wind and eddy diffusivity profiles on the basis of a diagnostic PBL model. The second one provides an eddy diffusivity profile based on the Taylor statistical diffusion theory and on the spectral pr operties of turbulence. The two parameterisations have been included in a numerical grid model and tested with the Copenhagen data set. Results show tha: i) the disper sion model with both turbulent schemes, produces a good fitting of the measured gr ound-level concentration data for all the experimental conditions considered; ii) th ere are no significant differences between the two schemes in the range of experimental data - the profiles are close to each other in the low...
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In this work is presented the development of an integrated model composed by a Neural Net and a dispersion model. Using the concentrations predicted by an air dispersion model (ADMD) as input to a Neural net, we evaluated the performances... more
In this work is presented the development of an integrated model composed by a Neural Net and a dispersion model. Using the concentrations predicted by an air dispersion model (ADMD) as input to a Neural net, we evaluated the performances of this new methodology in the cases of a releases from an elevated emission source using the urban data set of the Indianapolis field study as test case. INTRODUCTION The air pollution models constitute a sophisticated tools that reflects the knowledge on turbulent transport in the atmosphere. However, this models have not so far been able to reproduce satisfactorily ground level concentrations because the influence of important variables is not perfectly described. The results they provide are affected by a considerable margin of error, the most important of which is the uncertainty linked to the intrinsic variability of the atmosphere and to local topography. Most operative models for estimating the dispersion of gases and particles in the atmos...
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Abstract Aeolian dust from arid and semi-arid areas contributes significantly to the global atmospheric aerosol mass and is expected to impact the climate system by direct and indirect effects. The project Saharan Mineral dust experiment... more
Abstract Aeolian dust from arid and semi-arid areas contributes significantly to the global atmospheric aerosol mass and is expected to impact the climate system by direct and indirect effects. The project Saharan Mineral dust experiment (SAMUM) aims at ...
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In this work, expressions for the eddy diffusivities are obtained using differents values from the Corrsin's constant (γ= 0,44; γ= 0,55 and γ= 0,7). These eddy diffusivities are derived from the convective similarity theory and from... more
In this work, expressions for the eddy diffusivities are obtained using differents values from the Corrsin's constant (γ= 0,44; γ= 0,55 and γ= 0,7). These eddy diffusivities are derived from the convective similarity theory and from the one dimensional vertical turbulent velocity ...
In this work, expressions for the eddy diffusivities are obtained using differents values from the Corrsin's constant (γ= 0,44; γ= 0,55 and γ= 0,7). These eddy diffusivities are derived from the convective similarity theory and from... more
In this work, expressions for the eddy diffusivities are obtained using differents values from the Corrsin's constant (γ= 0,44; γ= 0,55 and γ= 0,7). These eddy diffusivities are derived from the convective similarity theory and from the one dimensional vertical turbulent velocity ...
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Page 1. Revista Brasileira de Meteorologia, v.19, n.2, 113-122, 2004 A SOLUTION OF THE STEADY K-DIFFUSION EQUATION FOR ABL DISPERSION IN INHOMOGENEOUS TURBULENCE WITH PLUME RISE *DAVIDSON ...
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Summary Over recent years several theoretical and experimental works have made it possible to evaluate the basic parameters describing the atmospheric boundary layer by means of elementary meteorological measurements in proximity to the... more
Summary Over recent years several theoretical and experimental works have made it possible to evaluate the basic parameters describing the atmospheric boundary layer by means of elementary meteorological measurements in proximity to the ground. This has ...
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This study aims to review the physical theory and parametrizations associated to Turbulent Kinetic Energy Density Function (STKE). The bibliographic references bring a broad view of the physical problem, mathematical techniques and... more
This study aims to review the physical theory and parametrizations associated to Turbulent Kinetic Energy Density Function (STKE). The bibliographic references bring a broad view of the physical problem, mathematical techniques and modeling of turbulent kinetic energy dynamics in the convective boundary layer. A simplified model based on the dynamical equation for the STKE, in an isotropic and homogeneous turbulent flow regime, is done by formulating and considering the isotropic inertial energy transfer and viscous dissipation terms. This model is described by the Cauchy Problem and solved employing the Method of Characteristics. Therefore, a discussion on Linear First Order Partial Differential Equation, its existence, and uniqueness of solution has been presented. The spectral function solution obtained from its associated characteristic curves and initial condition (Method of Characteristics) reproduces the main features of a modeled physical system. In addition, this modeling a...
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The paper presents the evaluation of a model, with a new vertical eddy exchange parameterization, based on a general technique for solving the K-equation, using the truncated Gram-Charlier expansion (type A) of the concentration field and... more
The paper presents the evaluation of a model, with a new vertical eddy exchange parameterization, based on a general technique for solving the K-equation, using the truncated Gram-Charlier expansion (type A) of the concentration field and a finite set equations for the corresponding moments. The model can be applied routinely using as input simple ground-level meteorological data acquired by an automatic network. A performance evaluation is shown in the case of continuous emission from an elevated source in a variable boundary layer.
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After setting realistic scenarios of the wind and diffusivity parameterizations the Ground Level Concentration is worked out by an analytical solution of the advection-diffusion equation, then an explicit approximate expression is... more
After setting realistic scenarios of the wind and diffusivity parameterizations the Ground Level Concentration is worked out by an analytical solution of the advection-diffusion equation, then an explicit approximate expression is provided for it allowing a simple expression for the position and value of the maximum.
The settling velocity and deposition of particulate matter on the earth's surface has been introduced in an analytical solution of advection-diffusion equation. The influence of particle diameters in ground level concentration... more
The settling velocity and deposition of particulate matter on the earth's surface has been introduced in an analytical solution of advection-diffusion equation. The influence of particle diameters in ground level concentration distribution was investigated in function of different atmospheric stability condiyions
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Neste trabalho apresentam-se os principais aspectos relacionados à meteorologia ligada ao processo de dispersão turbulenta de poluentes atmosféricos. Ressalta-se que a meteorologia desempenha um papel fundamental para o controle da... more
Neste trabalho apresentam-se os principais aspectos relacionados à meteorologia ligada ao processo de dispersão turbulenta de poluentes atmosféricos. Ressalta-se que a meteorologia desempenha um papel fundamental para o controle da qualidade do ar, pois os eventos meteorológicos guiam a dispersão de poluentes e sua deposição no solo. Discutem-se os recentes melhoramentos da descrição e previsão dos fenômenos que envolvem a poluição atmosférica considerando a melhoria da qualidade de vida da população.