Transport and diffusion in complex terrain (review)

Egan, Bruce A.

doi:10.1007/bf00121947

Cited by 26 publications

(10 citation statements)

References 23 publications

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“…(ex p [-0.5 e':zheJJ + exp [-0.5 e';zheJJ) Plume dispersion in the region of horizontal flow (fromEgan, 1984). [Reprinted with permission from D.…”

mentioning

confidence: 62%

“…Strongly stable conditions occur for 0 < Fr < 1, which is the case when Equation 11-1 applies. Egan (1984) describes how the Gaussian plume model in Equation 7-1 can be used to treat the two extremes of flow behaviors defined by whether streamlines are above or below He. For dispersion below He (i.e., the "wrap" component), the flow is restricted to travel in horizontal planes toward or around the sides of the hill, as shown in Figure 11-1 and in Region I of Figure 11-2.…”

mentioning

confidence: 99%

“…An overview of complex terrain modeling is given byEgan (1984),Egan and Schiermeier (1986), and Venkatram(Venkatram and Wyngaard, 1988).…”

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confidence: 99%

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Air Pollution Modeling

Zannetti

1990

240

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“…(ex p [-0.5 e':zheJJ + exp [-0.5 e';zheJJ) Plume dispersion in the region of horizontal flow (fromEgan, 1984). [Reprinted with permission from D.…”

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confidence: 62%

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confidence: 99%

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Air Pollution Modeling

Zannetti

1990

240

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“…One type of approach is to use the standard Gaussian dispersion model, modified to account for terrain influences. Hunt et al (1979), Misra (1980), Egan (1984), Andrén (1987) and Enger (1990c) describe examples of such models. Significant deviations from idealized conditions introduce limitations on the validity of Gaussian models, because model uncertainties might become too large.…”

Section: Introductionmentioning

confidence: 99%

The role of advection of fluxes in modelling dispersion in convective boundary layers

Abiodun¹,

Enger²

2002

Q. J. R. Meteorol. Soc.

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SUMMARYA Eulerian three-dimensional higher-order closure dispersion model is presented. The model uses mean wind and turbulence quantities from a second-order atmospheric boundary-layer model. The dispersion model is validated against results from tank and field experiments and compared to results from Lagrangian dispersion models. The results show quite good agreement with experiment and Lagrangian modelling results for point source dispersion in a convective boundary layer (CBL). Sensitivity studies with the model help to identify the role played by advection and horizontal transport terms in the equations for the fluxes in simulating the essential features of pollutant dispersion.Results from the sensitivity tests show that the characteristic features of dispersion from point sources in the CBL-with an ascending plume during ground-level release and a descending plume from a lifted point source-are caused by an imbalance between the advection and diffusion terms in the equation for the vertical flux. Furthermore, it is shown that there is also a tendency for the plume to split horizontally, which is similarly caused by an imbalance between the advection and diffusion terms in horizontal fluxes. The simulated lateral standard deviations of distance x from a point source, for the vertically integrated concentration, are proportional to x close to the source and to x 1/2 far away from the source, if and only if the advection and diffusion terms are included in the equations for the turbulent fluxes of concentration.

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“…Although none of these large research efforts is completed, they are at the stage where considerable field and laboratory experience has been gained. Also, a number of mathematical model development and evaluation activities have been pursued and findings from these experiences are rapidly becoming available (Egan, 1984;Schiermeier, 1984). For these reasons, the AMS Steering Committee for the EPA Cooperative Agreement decided that it would be appropriate to review the progress made in this field and to encourage a discussion about what has been learned, what the implications are to present practice in dispersion modeling, and what these experiences might suggest with respect to possible augmentations to current research efforts.…”

Section: Introductionmentioning

confidence: 99%

Dispersion in Complex Terrain: A Summary of the AMS Workshop held in Keystone, Colorado, 17–20 May 1983

Egan¹,

Schiermeier²

1986

Bull. Amer. Meteor. Soc.

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This article summarizes a workshop convened under the direction of the AMS Steering Committee for the EPA (Environmental Protection Agency) Cooperative Agreement on Air Quality Modeling. The purpose of the workshop was to address the status of our understanding of dispersion i n complex or mountainous terrain settings, with a specific focus on the ability of current technologies to predict air pollution concentrations in different terrain settings. The meteorological phenomena of importance for estimating the effects of elevated plumes interacting with high terrain are described i n detail. Current understanding of the problems associated with lee-side flows and valley meteorology are also addressed. The present operational status of physical and mathematical modeling capabilities is summarized in relation to various terrain configurations. The participants provided a number of recommendations, both on the general use of the present science and also on seven specific areas where further research is needed in order to substantially improve our ability to reliably assess the effects of dispersion in complex terrain. These specific recommendations are accompanied by more-general perspectives regarding the fundamental complexity of stratified-fluid dynamics when coupled with topographic environments .

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Transport and diffusion in complex terrain (review)

Cited by 26 publications

References 23 publications

Air Pollution Modeling

Air Pollution Modeling

The role of advection of fluxes in modelling dispersion in convective boundary layers

Dispersion in Complex Terrain: A Summary of the AMS Workshop held in Keystone, Colorado, 17–20 May 1983

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