Numerical approximation to the effects of the atmospheric stability conditions on the dispersion of pollutants over flat areas

AbstractUsing the Computational Fluid Dynamics technique (CFD), we explored the effects of the atmospheric stability conditions on the dispersion of solid and gas-phase pollutants emitted from an area source located on a flat region. As an application, the dispersion of pollutants emitted from roads located on flat terrains was considered. Toward that end, we set up a model that describes the dispersion of air pollutants in a small region (< 1 km long) near the ground surface (< 250 m high). It consists of a neutrally stratified model modified to account for the atmospheric stability effects by imposing the near-ground stratification through the Monin–Obukhov similarity theory and the k–ε turbulence model adjusted for each atmospheric stability condition. Using this model, we simulated the dispersion of pollutants emitted from the road and plotted the resulting downwind concentrations in terms of dimensionless numbers. Results from our CFD-based model were highly correlated (R2 > 0.95) with the SF6 concentrations measured downwind a line source of this trace gas by the U.S. National Oceanic Atmospheric Administration in 2008 under different conditions of atmospheric stability. Numerical and experimental results showed that, under any of the stability conditions explored, the near-road pollutant concentrations are highly correlated (R2 > 0.87) to the concentrations observed under neutral conditions. When the atmosphere is extremely stable, those concentrations were up to 12 times higher than those observed under neutral conditions. We report the constant of proportionality obtained for every stability condition.

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Accounting for atmospheric stability conditions in urban heat island studies: The case of Glasgow, UK

Landscape and Urban Planning ◽

10.1016/j.landurbplan.2013.04.019 ◽

2013 ◽

Vol 117 ◽

pp. 112-121 ◽

Cited By ~ 16

Author(s):

Eduardo Krüger ◽

Rohinton Emmanuel

Keyword(s):

Urban Heat Island ◽

Atmospheric Stability ◽

Stability Conditions ◽

Heat Island ◽

Urban Heat

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Generation of an Isogenic Collection of Yeast Actin Mutants and Identification of Three Interrelated Phenotypes

Genetics ◽

10.1093/genetics/157.2.533 ◽

2001 ◽

Vol 157 (2) ◽

pp. 533-543

Author(s):

Johanna L Whitacre ◽

Dana A Davis ◽

Kurt A Toenjes ◽

Sharon M Brower ◽

Alison E M Adams

Keyword(s):

Crystal Structure ◽

Growth Rates ◽

Small Region ◽

Wild Type ◽

Large Collection ◽

Growth Defects ◽

Cytoskeletal Function ◽

Highly Correlated ◽

The Relationship ◽

Mutant Cells

Abstract A large collection of yeast actin mutations has been previously isolated and used in numerous studies of actin cytoskeletal function. However, the various mutations have been in congenic, rather than isogenic, backgrounds, making it difficult to compare the subtle phenotypes that are characteristic of these mutants. We have therefore placed 27 mutations in an isogenic background. We used a subset of these mutants to compare the degree to which different actin alleles are defective in sporulation, endocytosis, and growth on NaCl-containing media. We found that the three phenotypes are highly correlated. The correlations are specific and not merely a reflection of general growth defects, because the phenotypes are not correlated with growth rates under normal conditions. Significantly, those actin mutants exhibiting the most severe phenotypes in all three processes have altered residues that cluster to a small region of the actin crystal structure previously defined as the fimbrin (Sac6p)-binding site. We examined the relationship between endocytosis and growth on salt and found that shifting wild-type or actin mutant cells to high salt reduces the rate of α-factor internalization. These results suggest that actin mutants may be unable to grow on salt because of additive endocytic defects (due to mutation and salt).

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An Analytic Model for Dispersion of Rocket Exhaust Clouds: Specifications and Analysis in Different Atmospheric Stability Conditions

Journal of Aerospace Technology and Management ◽

10.5028/jatm.v7i3.510 ◽

2015 ◽

Vol 7 (3) ◽

pp. 374-385 ◽

Cited By ~ 2

Author(s):

Bruno Kabke Bainy ◽

Daniela Buske ◽

Régis Sperotto Quadros

Keyword(s):

Atmospheric Stability ◽

Stability Conditions ◽

Analytic Model ◽

Rocket Exhaust

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Can Wind Lidars Measure Turbulence?

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-10-05004.1 ◽

2011 ◽

Vol 28 (7) ◽

pp. 853-868 ◽

Cited By ~ 103

Author(s):

A. Sathe ◽

J. Mann ◽

J. Gottschall ◽

M. S. Courtney

Keyword(s):

Continuous Wave ◽

Atmospheric Stability ◽

Test Site ◽

Systematic Errors ◽

Stability Conditions ◽

Pass Filter ◽

Low Pass Filter ◽

Wind Speeds ◽

Sonic Anemometers ◽

Velocity Variance

Abstract Modeling of the systematic errors in the second-order moments of wind speeds measured by continuous-wave (ZephIR) and pulsed (WindCube) lidars is presented. These lidars use the conical scanning technique to measure the velocity field. The model captures the effect of volume illumination and conical scanning. The predictions are compared with the measurements from the ZephIR, WindCube, and sonic anemometers at a flat terrain test site under different atmospheric stability conditions. The sonic measurements are used at several heights on a meteorological mast in combination with lidars that are placed on the ground. Results show that the systematic errors are up to 90% for the vertical velocity variance, whereas they are up to 70% for the horizontal velocity variance. For the ZephIR, the systematic errors increase with height, whereas for the WindCube, they decrease with height. The systematic errors also vary with atmospheric stability and are low for unstable conditions. In general, for both lidars, the model agrees well with the measurements at all heights and under different atmospheric stability conditions. For the ZephIR, the model results are improved when an additional low-pass filter for the 3-s scan is also modeled. It is concluded that with the current measurement configuration, these lidars cannot be used to measure turbulence precisely.

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Optimizing Window Length for Turbulent Heat Flux Calculations from Airborne Eddy Covariance Measurements under Near Neutral to Unstable Atmospheric Stability Conditions

Remote Sensing ◽

10.3390/rs10050670 ◽

2018 ◽

Vol 10 (5) ◽

pp. 670 ◽

Cited By ~ 2

Author(s):

Yibo Sun ◽

Li Jia ◽

Qiting Chen ◽

Chaolei Zheng

Keyword(s):

Heat Flux ◽

Eddy Covariance ◽

Atmospheric Stability ◽

Turbulent Heat Flux ◽

Stability Conditions ◽

Turbulent Heat ◽

Window Length ◽

Eddy Covariance Measurements

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Fluxes of Gaseous Elemental Mercury on a Mediterranean Coastal Grassland

Atmosphere ◽

10.3390/atmos10090485 ◽

2019 ◽

Vol 10 (9) ◽

pp. 485

Author(s):

Christiana Polyzou ◽

Glykeria Loupa ◽

Aikaterini Trepekli ◽

Spyridon Rapsomanikis

Keyword(s):

Turbulent Mixing ◽

Rural Areas ◽

Similarity Theory ◽

Atmospheric Stability ◽

Elemental Mercury ◽

Mean Value ◽

Potential Influence ◽

Northern Greece ◽

Gaseous Elemental Mercury ◽

Rain Events

Coastal rural areas can be a source of elemental mercury, but the potential influence of their topographic and climatic particularities on gaseous elemental mercury (GEM) fluxes have not been investigated extensively. In this study, gaseous elemental mercury was measured over Mediterranean coastal grassland located in Northern Greece from 2014 to 2015 and GEM fluxes were evaluated utilizing Monin–Obukhov similarity theory. The GEM fluxes ranged from –50.30 to 109.69 ng m−2 h−1 with a mean value equal to 10.50 ± 19.14 ng m−2 h−1. Concerning the peak events, with high positive and low negative GEM fluxes, those were recorded from the morning until the evening. Rain events were a strong contributing factor for enhanced GEM fluxes. The enhanced turbulent mixing under daytime unstable conditions led to greater evasion and positive GEM fluxes, while, during nighttime periods, the GEM evasion is lower, indicating the effect of atmospheric stability on GEM fluxes. The coastal grassland with its specific characteristics influences the GEM fluxes and this area could be characterized as a source of elemental mercury. This study is one of the rare efforts in the research community to estimate GEM fluxes in a coastal natural site based on aerodynamic gradient method.

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Evaluation of methods for estimating atmospheric stability at two coastal sites

Wind Engineering ◽

10.1177/0309524x18780378 ◽

2018 ◽

Vol 42 (6) ◽

pp. 561-575 ◽

Cited By ~ 1

Author(s):

Lars Morten Bardal ◽

Anja Eide Onstad ◽

Lars Roar Sætran ◽

John Amund Lund

Keyword(s):

Surface Layer ◽

Richardson Number ◽

Atmospheric Stability ◽

Stability Conditions ◽

Bulk Richardson Number ◽

Wind Speed Profile ◽

Flux Measurements ◽

Vertical Wind Speed ◽

Stability Measurements ◽

Evaluation Of Methods

Understanding the atmospheric stability conditions is important in order to obtain accurate estimates of the vertical wind speed profile. This work compares and evaluates common methods for estimation of atmospheric stability using standard meteorological mast observations. Atmospheric stability distributions from three different met-masts located at two coastal sites are calculated and compared. The atmospheric stability parameter, L is estimated using the bulk Richardson number, the surface-layer Richardson number, and calculated directly from eddy covariance flux measurements. The resulting distributions vary depending on which method is used. The atmospheric stability measurements from two masts located 3 km apart in similar terrain are compared directly. The highest correlation is found for the surface-layer Richardson number method. This method it also less sensitive to variation of measurement heights than the bulk Richardson number method.

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Wind Turbulence Statistics of the Atmospheric Inertial Sublayer under Near-Neutral Conditions

Atmosphere ◽

10.3390/atmos11101087 ◽

2020 ◽

Vol 11 (10) ◽

pp. 1087

Author(s):

Eslam Reda Lotfy ◽

Zambri Harun

Keyword(s):

Boundary Layer ◽

Atmospheric Stability ◽

Turbulent Velocity ◽

Stability Conditions ◽

Mean Velocity ◽

Law Of The Wall ◽

Turbulent Statistics ◽

The Mean ◽

The Law ◽

Velocity Variances

The inertial sublayer comprises a considerable and critical portion of the turbulent atmospheric boundary layer. The mean windward velocity profile is described comprehensively by the Monin–Obukhov similarity theory, which is equivalent to the logarithmic law of the wall in the wind tunnel boundary layer. Similar logarithmic relations have been recently proposed to correlate turbulent velocity variances with height based on Townsend’s attached-eddy theory. The theory is particularly valid for high Reynolds-number flows, for example, atmospheric flow. However, the correlations have not been thoroughly examined, and a well-established model cannot be reached for all turbulent variances similar to the law of the wall of the mean-velocity. Moreover, the effect of atmospheric thermal condition on Townsend’s model has not been determined. In this research, we examined a dataset of free wind flow under a near-neutral range of atmospheric stability conditions. The results of the mean velocity reproduce the law of the wall with a slope of 2.45 and intercept of −13.5. The turbulent velocity variances were fitted by logarithmic profiles consistent with those in the literature. The windward and crosswind velocity variances obtained the average slopes of −1.3 and −1.7, respectively. The slopes and intercepts generally increased away from the neutral state. Meanwhile, the vertical velocity and temperature variances reached the ground-level values of 1.6 and 7.8, respectively, under the neutral condition. The authors expect this article to be a groundwork for a general model on the vertical profiles of turbulent statistics under all atmospheric stability conditions.

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