An analytical model with temporal variable eddy diffusivity applied to contaminant dispersion in the atmospheric boundary layer

2012 ◽  
Vol 391 (8) ◽  
pp. 2576-2584 ◽  
Author(s):  
M.T. Vilhena ◽  
D. Buske ◽  
G.A. Degrazia ◽  
R.S. Quadros
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Analytical Model ◽  
Eddy Diffusivity ◽  
Contaminant Dispersion ◽  
Temporal Variable

An analytical model for dispersion of pollutants from a continuous source in the atmospheric boundary layer

2009 ◽  
Vol 466 (2114) ◽  
pp. 383-406 ◽  
Author(s):  
Pramod Kumar ◽  
Maithili Sharan
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Atmospheric Boundary Layer ◽  
Analytical Model ◽  
Eddy Diffusivity ◽  
Horizontal Wind ◽  
Advection Diffusion Equation ◽  
Special Cases ◽  
Vertical Height ◽  
Continuous Source

For the dispersion of a pollutant released from a continuous source in the atmospheric boundary layer (ABL), a generalized analytical model describing the crosswind-integrated concentrations is presented. An analytical scheme is described to solve the resulting two-dimensional steady-state advection–diffusion equation for horizontal wind speed as a generalized function of vertical height above the ground and eddy diffusivity as a function of both downwind distance from the source and vertical height. Special cases of this model are deduced and an extensive analysis is carried out to compare the model with the known analytical models by taking the particular forms of wind speed and vertical eddy diffusivity. The proposed model is evaluated with the observations obtained from Copenhagen diffusion experiments in unstable conditions and Hanford and Prairie Grass experiments in stable conditions. In evaluation of the model, a recently proposed formulation for the wind speed in the entire ABL is used. It is concluded that the present model is performing well with the observations and can be used to predict the short-range dispersion from a continuous release. Further, it is shown that the accurate parameterizations of wind speed and eddy diffusivity provide a significant improvement in the agreement between computed and observed concentrations.

scholarly journals An Analytical Model for the Regeneration of Wind after Exiting a Wind Farm

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2071
Author(s):  
Brian Fiedler
Keyword(s):  
Boundary Layer ◽  
Pressure Gradient ◽  
Atmospheric Boundary Layer ◽  
Linear Model ◽  
Analytical Model ◽  
Environmental Conditions ◽  
Wind Farm ◽  
Length Scale ◽  
Equilibrium Calculation ◽  
Friction Pressure

The simplest model for an atmospheric boundary layer assumes a uniform steady wind over a certain depth, of order 1 km, with the forces of friction, pressure gradient and Coriolis in balance. A linear model is here employed for the adjustment of wind to this equilibrium, as the wake of a very wide wind farm. A length scale is predicted for the exponential adjustment to equilibrium. Calculation of this length scale is aided by knowledge of the angle for which the wind would normally cross the isobars in environmental conditions in the wake.

scholarly journals A Shear-Based Parameterization of Turbulent Mixing in the Stable Atmospheric Boundary Layer

2015 ◽  
Vol 72 (5) ◽  
pp. 1713-1726 ◽  
Author(s):  
Jordan M. Wilson ◽  
Subhas K. Venayagamoorthy
Keyword(s):  
Boundary Layer ◽  
Stress Intensity ◽  
Kinetic Energy ◽  
Atmospheric Boundary Layer ◽  
Turbulent Mixing ◽  
Intensity Ratio ◽  
Eddy Diffusivity ◽  
Stable Atmospheric Boundary Layer ◽  
Turbulent Momentum ◽  
Shear Production

Abstract In this study, shear-based parameterizations of turbulent mixing in the stable atmospheric boundary layer (SABL) are proposed. A relevant length-scale estimate for the mixing length of the turbulent momentum field is constructed from the turbulent kinetic energy and the mean shear rate S as . Using observational data from two field campaigns—the Surface Heat Budget of the Arctic Ocean (SHEBA) experiment and the 1999 Cooperative Atmosphere–Surface Exchange Study (CASES-99)— is shown to have a strong correlation with . The relationship between and corresponds to the ratio of the magnitude of the tangential components of the turbulent momentum flux tensor to , known as stress intensity ratio, . The field data clearly show that is linked to stability. The stress intensity ratio also depends on the flow energetics that can be assessed using a shear-production Reynolds number, , where P is shear production of turbulent kinetic energy and is the kinematic viscosity. This analysis shows that high mixing rates can indeed persist at strong stability. On this basis, shear-based parameterizations are proposed for the eddy diffusivity for momentum, , and eddy diffusivity for heat, , showing remarkable agreement with the exact quantities. Furthermore, a broader assessment of the proposed parameterizations is given through an a priori evaluation of large-eddy simulation (LES) data from the first GEWEX Atmospheric Boundary Layer Study (GABLS). The shear-based parameterizations outperform many existing models in predicting turbulent mixing in the SABL. The results of this study provide a framework for improved representation of the SABL in operational models.

scholarly journals Parameterization of vertical diffusion and the atmospheric boundary layer height determination in the EMEP model

2010 ◽  
Vol 10 (2) ◽  
pp. 341-364 ◽  
Author(s):  
A. Jeričević ◽  
L. Kraljević ◽  
B. Grisogono ◽  
H. Fagerli ◽  
Ž. Večenaj
Keyword(s):  
Boundary Layer ◽  
Air Pollution ◽  
Atmospheric Boundary Layer ◽  
Model Development ◽  
Monitoring And Evaluation ◽  
Eddy Diffusivity ◽  
Mixing Height ◽  
Vertical Diffusion ◽  
Height Determination ◽  
Stable Conditions

Abstract. This paper introduces two changes of the turbulence parameterization for the EMEP (European Monitoring and Evaluation Programme) Eulerian air pollution model: the replacement of the Blackadar in stable and O'Brien in unstable turbulence formulations with an analytical vertical diffusion profile (K(z)) called Grisogono, and a different mixing height determination, based on a bulk Richardson number formulation (RiB). The operational or standard (STD) and proposed new parameterization for eddy diffusivity have been validated in all stability conditions against the observed daily surface nitrogen dioxide (NO2), sulphur dioxide (SO2) and sulphate (SO42−) concentrations at different EMEP stations during the year 2001. A moderate improvement in the correlation coefficient and bias for NO2 and SO2 and a slight improvement for sulphate is found for the most of the analyzed stations with the Grisogono K(z) scheme, which is recommended for further application due to its scientific and technical advantages. The newly extended approach for the mechanical eddy diffusivity is applied to the Large Eddy Simulation data focusing at the bulk properties of the neutral and stable atmospheric boundary layer. A summary and extension of the previous work on the empirical coefficients in neutral and stable conditions is provided with the recommendations to the further model development. Special emphasis is given to the representation of the ABL in order to capture the vertical transport and dispersion of the atmospheric air pollution. Two different schemes for the ABL height determination are evaluated against the radiosounding data in January and July 2001, and against the data from the Cabauw tower, the Netherlands, for the same year. The validation of the ABL parameterizations has shown that the EMEP model is able to reproduce spatial and temporal mixing height variability. Improvements are identified especially in stable conditions with the new ABL height scheme based on the RiB number.

scholarly journals Parameterization of vertical diffusion and the atmospheric boundary layer height determination in the EMEP model

2009 ◽  
Vol 9 (2) ◽  
pp. 9597-9645 ◽  
Author(s):  
A. Jeričević ◽  
L. Kraljević ◽  
B. Grisogono ◽  
H. Fagerli
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Monitoring And Evaluation ◽  
Eddy Diffusivity ◽  
Vertical Diffusion ◽  
Boundary Layer Height ◽  
Eddy Simulation ◽  
Height Determination ◽  
Stable Conditions ◽  
Diffusion Scheme

Abstract. A new vertical diffusion scheme, called Grisogono, has been implemented in the Unified EMEP (European Monitoring and Evaluation Programme) model. It is shown based on Large Eddy Simulation (LES) that the Grisogono method performs better than the operational O'Brien's polynomial, especially in the stable conditions. In this work, the operational and proposed new parameterization for eddy diffusivity K(z) have been validated against observed daily surface nitrogen dioxide (NO2), sulphur dioxide (SO2) and sulphate (SO4−2) concentrations at different EMEP stations during year 2001. Moderate improvement in the correlation coefficient and bias for NO2 and SO2 and slight improvement for sulphate is found for most of the analyzed stations with the Grisogono K(z) scheme, which is recommended for further application due to its scientific and technical advantages. Special emphasis is given to the representation of the atmospheric boundary layer (ABL) in order to capture vertical transport and dispersion of atmospheric air pollution. Two different ABL schemes are evaluated against radiosounding data in January and July 2001, and against data from the Cabauw tower, the Netherlands, in the same year. Based on validation of the ABL parameterizations, it is found that the EMEP model is able to reproduce spatial and temporal mixing height variability. Improvements are identified especially in stable conditions with the new ABL scheme based on the bulk Richardson number (RiB).

Sign in / Sign up

Export Citation Format

Share Document