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A modified version of the DALES model version 4.2 for the purpose of studying ammonia plume dispersion in a polluted atmosphere. With the data in this repository, the fine-scale simulation framework can be applied to individual locations to study the representativity of (potential new) measurement sites under the local conditions, using the concept of blending-distance. This repository contains the modified DALES code, instruction, MATLAB processing scripts and example input files of the reference experiment are added to the repository. The modifications with respect to DALES v4.2 are described in the publication.

The dispersion of air pollutants emitted from industries has been studied ever since the dawn of industrialisation. The present work focuses on investigating the effect of negative atmospheric temperature gradient and the plume stack orientation of two individual equal-height stacks on the vertical rise and dispersion of the plume. The study carried out upon three-stack layout configurations namely inline, 45° and non-inline, separated by an inter-stack distance of 12 times the exit chimney diameter (12 D) and 22 times the exit chimney diameter (22 D) in each case over the two temperature gradients of −0.2 K/100 m and −0.5 K/100 m. The turbulence is modelled using realisable k-ε model, a model used in the FLUENT flow solver. In the case of the inline configuration, the upwind plume shields its downwind counterpart, which in turn allows for higher plume rise at a given temperature gradient. The plume oscillates more in the case of inline than 45° and non-inline cases. Also, for a temperature gradient of −0.5 K/100 m, the plumes oscillate violently in the vertical direction, mainly because, with the initial rise of the plume, cold air from higher altitudes moves down and forms a layer of lower temperature closer to the ground. The present study is important to highlight the plume dispersion characteristics under negative temperature gradient conditions., Aerodynamics, Wind Energy & Propulsion

Seawater desalination has been considered an important solution for the water scarcity in coastal areas. Brazil has an 8,000 km long coastline where population and tourism have grown tremendously in the last years. Fortaleza is the fifth-largest city in Brazil with nearly 2.6 million inhabitants, representing an important economic, recreational and touristic area in the Northeast. In addition, it is the city with the greatest gross domestic product (GDP) in the region, and ninth in the country. In the past 7 y, the dams that supply water to the Metropolitan Region of Fortaleza have undergone droughts. This led the government to start a large-scale seawater desalination project that shall produce desalinated water at about 1.0 m3/s, for which plant location, water intake and brine disposal studies were performed. The most common environmental impact associated with desalination plants is the high concentration brine discharge. Aiming to evaluate the possible impact of such discharges, environmental modeling has become an important tool for projects, environmental management and studies, due to the complexity of these environments. With this tool, it is possible to integrate a large number of variables and processes to obtain a dynamic vision of those systems and evaluate present and future conditions. This work presents outcomes from brine discharge modeling in the water quality of the coast of Fortaleza, in particular, increased salinity, using Visual Plumes to evaluate near-field dilution and SisBaHiA (Environmental Hydrodynamic Base System) software to generate a hydrodynamic model and evaluate far-field dilution. Hydrodynamic models, forced by wind and tide, were coupled with a wave propagation model and then used in a Lagrangian transport model, which was fed by the outcomes of the near-field model. From the results generated, it was identified that the installation of the proposed desalination plant in Fortaleza does not compromise water quality and is consiste

Seawater desalination has been considered an important solution for the water scarcity in coastal areas. Brazil has an 8,000 km long coastline where population and tourism have grown tremendously in the last years. Fortaleza is the fifth-largest city in Brazil with nearly 2.6 million inhabitants, representing an important economic, recreational and touristic area in the Northeast. In addition, it is the city with the greatest gross domestic product (GDP) in the region, and ninth in the country. In the past 7 y, the dams that supply water to the Metropolitan Region of Fortaleza have undergone droughts. This led the government to start a large-scale seawater desalination project that shall produce desalinated water at about 1.0 m3/s, for which plant location, water intake and brine disposal studies were performed. The most common environmental impact associated with desalination plants is the high concentration brine discharge. Aiming to evaluate the possible impact of such discharges, environmental modeling has become an important tool for projects, environmental management and studies, due to the complexity of these environments. With this tool, it is possible to integrate a large number of variables and processes to obtain a dynamic vision of those systems and evaluate present and future conditions. This work presents outcomes from brine discharge modeling in the water quality of the coast of Fortaleza, in particular, increased salinity, using Visual Plumes to evaluate near-field dilution and SisBaHiA (Environmental Hydrodynamic Base System) software to generate a hydrodynamic model and evaluate far-field dilution. Hydrodynamic models, forced by wind and tide, were coupled with a wave propagation model and then used in a Lagrangian transport model, which was fed by the outcomes of the near-field model. From the results generated, it was identified that the installation of the proposed desalination plant in Fortaleza does not compromise water quality and is consiste

[Abstract]: A framework based on a mixed reality simulator for coordinating teams of autonomous Unmanned Aerial Vehicles (UAVs) is been developed. This framework would serve as a tool to facilitate crossing the reality gap for different applications; particularly when using these UAVs teams for air pollution monitoring and measurement. The system is built on a co-evolutionary simulator that makes use of data transmitted from some real UAVs to integrate them within a team of simulated UAVs. The system allows the progressive increase of the number of real UAV in the team. This facilitates the setting-up of a single UAV control system and also of the UAV collaboration schemes for different scenarios. A specific implementation of this system focussed on mapping the pollutant dispersion of a plume in the atmosphere is presented. Implementing an appropriate pollution dispersion model within the simulator is a key aspect of the system. This model should require few computational resources, should be easy to adapt in real time to ambient changes, and it should have a fair accuracy.

We have developed a LOcal-scale High-resolution atmospheric DIspersion Model using Large-Eddy Simulation (LOHDIM-LES) to assess the safety at nuclear facilities and to respond to emergency situations resulting from accidental or deliberate releases of radioactive materials (e.g., a terrorist attack in an urban area). In parts 1–4, LESs of turbulent flows and plume dispersion over a flat terrain, around an isolated building, within building arrays with different obstacle densities, and within an actual urban area were performed, which showed the basic performance comparable to wind tunnel experimental technique. In this study, we extend the LOHDIM-LES to turbulent flows and plume dispersion in an actual urban area under real meteorological conditions by coupling with a meso-scale meteorological simulation model. The LES results of wind speed, wind direction, and concentration values are generally reproduced well. It is concluded that our coupling approach between LES and meso-scale meteorological models is effective in detailed simulations of turbulent flows and plume dispersion in urban areas under real meteorological conditions.

Eyjafjallajökull 2010 and Grímsvötn 2011 eruptions created great problems for commercial aviation in the North Atlantic because of the large extent of the predicted ash clouds from these eruptions. Comparison to satellite pictures showed the predictions very much larger than the ash cloud. Measurements also showed lower ash concentrations over Europe than the predicted. Papers on simulation of the Eyjafjallajökull Ash cloud in peer reviewed journals, usually tried to simulate the VAAC predictions rather than the satellite pictures, an example is shown. In the newest eruption in Iceland (Holuhraun – Bardarbunga) mostly SO2 was produced but if its output had been ash, it could have produced similar problems for the aviation as Eyjafjallajökull did. The plume was successfully modeled using the WRF-chem model. Kyoto Universities measurements and research of eruptions in Sakurajima has shown weak points in the diffusion theory used for ash cloud prediction of tropospheric plumes that tend to ride in stable temperature inversions

This research addresses theoretical and computational issues for estimation of gas concentration associated with an emitting stationary or moving source. Estimation of the concentration field provides a superior ability for detection of the gas source location, assessment of possible impacts and eventual containment. The model based concentration estimation is made possible via a sensing aerial vehicle (SAV). The theoretical component considers an abstract and finite-dimensional approximation framework that strongly couples theoretical estimation and control with advanced computational fluid dynamics methods. The gas dispersion model is based on the 2D advection diffusion equation with variable eddy diffusivities and ambient winds. The process state estimator is based on a 2D adaptive, multi grid, multi step finite volume method with upwind and flux limiting. The grid is adapted with local refinement and coarsening during the process state estimation, in order to improve accuracy and efficiency. The SAV motion dynamics is incorporated into the spatial process and its guidance is linked to the performance of the state estimator., The original document contains color images.

Desalination of seawater has been considered as a potential solution for the water shortage problem in coastal areas and the number of projected and constructed desalination plants has significantly increased in recent years. The challenge of the desalination industry is to produce new water resources without increasing the pressure on the marine environment. Environmental impact of SWRO desalination plants is mainly associated with the discharge into the sea of the brine produced. To estimate the area of influence of the brine several models have been proposed, but validation with real data is needed. The objective of this paper is to present the results of the monitoring of the brine effluent emanating from several SWRO desalination plants in the western Mediterranean Sea in order to estimate the area of influence of the hypersaline plume. We also illustrate how the behavior of these brine discharges can differ significantly according to discharge characteristics. This information may be useful to predict effluent distribution in order to minimize the harmful effects of brine discharges into the sea.

Desalination of seawater has been considered as a potential solution for the water shortage problem in coastal areas and the number of projected and constructed desalination plants has significantly increased in recent years. The challenge of the desalination industry is to produce new water resources without increasing the pressure on the marine environment. Environmental impact of SWRO desalination plants is mainly associated with the discharge into the sea of the brine produced. To estimate the area of influence of the brine several models have been proposed, but validation with real data is needed. The objective of this paper is to present the results of the monitoring of the brine effluent emanating from several SWRO desalination plants in the western Mediterranean Sea in order to estimate the area of influence of the hypersaline plume. We also illustrate how the behavior of these brine discharges can differ significantly according to discharge characteristics. This information may be useful to predict effluent distribution in order to minimize the harmful effects of brine discharges into the sea.

Compared to dry boundary layers, dispersion in cloud-topped boundary layers has received less attention. In this LES based numerical study we investigate the dispersion of a passive tracer in the form of Lagrangian particles for four kinds of atmospheric boundary layers: 1) a dry convective boundary layer (for reference), 2) a "smoke" cloud boundary layer in which the turbulence is driven by radiative cooling, 3) a stratocumulus topped boundary layer and 4) a shallow cumulus topped boundary layer. We show that the dispersion characteristics of the smoke cloud boundary layer as well as the stratocumulus situation can be well understood by borrowing concepts from previous studies of dispersion in the dry convective boundary layer. A general result is that the presence of clouds enhances mixing and dispersion ¿ a notion that is not always reflected well in traditional parameterization models, in which clouds usually suppress dispersion by diminishing solar irradiance. The dispersion characteristics of a cumulus cloud layer turn out to be markedly different from the other three cases and the results can not be explained by only considering the well-known top-hat velocity distribution. To understand the surprising characteristics in the shallow cumulus layer, this case has been examined in more detail by 1) determining the velocity distribution conditioned on the distance to the nearest cloud and 2) accounting for the wavelike behaviour associated with the stratified dry environment

In 2005, Park et al., developed a new Pseudo-Deterministic Receptor Model (PDRM) to apportion SO2 and ambient particulate matter (PM) constituents to local sources near Tampa Bay. Ambient pollutant measurements were fit to products of emission rates and dispersion factors constrained with a Gaussian plume model for individual sources. In our study, the original samples were reanalyzed by ICPMS for 10 additional elements to improve the resolving power. Chemical mass balance (CMB) terms were added to PDRM to allow fitting of background aerosol sources. More accurate, curvilinear plume trajectories were computed to predict arrival times in both surface and aloft layers. This allowed application of the PDRM complicated meteorological conditions, e.g. wind shifts. Predicted emission rates for particle-bound elements were constrained using chemical compositional information obtained from published source profiles for generic source types. Constraints applied to source emissions of known tracer species allowed the "conditioning" of predicted dispersion factors for those sources to tracer species concentration profiles to better determine the dispersion factor temporal profiles. This enabled the model to apportion pollutants to individual sources with intermittent emissions the omission of which in Park et al. lead to significant residuals. Excellent fits were obtained for all modeled pollutants: 14 of 22 species have Normalized Mean Square Error (NMSE) values of < 2.5% and 21 of 22 have values < 8%. These were improved for SO2 and 8 of 10 elements (by 7-35% for Al, Cu, Ni, Pb, and Zn) modeled by Park et al. Our predicted emission rates are in much better agreement with chemical compositions for generic source types. Key results include: (1) predicted SO2 contributions to ambient levels from a small, lead battery recycling plant that were reduced from 50-59% at its peak influence to a more reasonable 2-4%, (2) Pb/Zn ratios from that plant increased from 1.0 to 734 and bette

Ultrafine vehicular particle (<100 nm) number size distributions presented in the literature are mostly averages of long scan-time (similar to 30 s or more) spectra mainly due to the non-availability of commercial instruments that can measure particle distributions in the <10 nm to 100 nm range faster than 30 s even though individual researchers have built faster (1-2.5 s) scanning instruments. With the introduction of the Engine Exhaust Particle Sizer (EEPS) in 2004, high time-resolution (1 full 32-channel spectrum per second) particle size distribution data become possible and allow atmospheric researchers to study the characteristics of ultrafine vehicular particles in rapidly and perhaps randomly varying high concentration environments such as roadside, on-road and tunnel. In this study, particle size distributions in these environments were found to vary as rapidly as one second frequently. This poses the question on the generality of using averages of long scan-time spectra for dynamic and/or mechanistic studies in rapidly and perhaps randomly varying high concentration environments. One-second EEPS data taken at roadside, on roads and in tunnels by a mobile platform are time-averaged to yield 5, 10, 30 and 120 s distributions to answer this question.

Volatilization of pesticides from crops in the field can be an important emission pathway. In a field experiment with characterization of meteorological conditions, the pesticides chlorpyrifos and fenpropimorph were sprayed onto a potato crop, after which concentrations in the air and on/in the plants were measured. Rates of volatilization were estimated with the aerodynamic profile (ADP), energy balance (EB), relaxed eddy accumulation (REA), and plume dispersion (PD) methods. The volatilization rates obtained with the ADP and EB methods were similar, while some rates obtained with the REA and PD methods in the initial period were lower. Cumulative volatilization of chlorpyrifos during daylight hours (ADP and EB methods) was estimated to be about 65% of the dosage. By far the majority of this volatilization occurred in the first few days. Competing processes at the plant surface had a considerable effect on the dissipation of fenpropimorph, so cumulative volatilization during daylight hours was estimated to be only 7% of the dosage. Plant surface residues were higher than would correspond with the volatilization rate, indicating that penetration into the leaves had occurred. © 2006 American Chemical Society.

Ultrafine vehicular particle (<100 nm) number size distributions presented in the literature are mostly averages of long scan-time (similar to 30 s or more) spectra mainly due to the non-availability of commercial instruments that can measure particle distributions in the <10 nm to 100 nm range faster than 30 s even though individual researchers have built faster (1-2.5 s) scanning instruments. With the introduction of the Engine Exhaust Particle Sizer (EEPS) in 2004, high time-resolution (1 full 32-channel spectrum per second) particle size distribution data become possible and allow atmospheric researchers to study the characteristics of ultrafine vehicular particles in rapidly and perhaps randomly varying high concentration environments such as roadside, on-road and tunnel. In this study, particle size distributions in these environments were found to vary as rapidly as one second frequently. This poses the question on the generality of using averages of long scan-time spectra for dynamic and/or mechanistic studies in rapidly and perhaps randomly varying high concentration environments. One-second EEPS data taken at roadside, on roads and in tunnels by a mobile platform are time-averaged to yield 5, 10, 30 and 120 s distributions to answer this question.

Eulerian and Lagrangian statistics in the atmospheric convective boundary layer (CBL) are studied by means of large eddy simulation (LES). Spectra analysis is performed in both the Eulerian and Lagrangian frameworks, autocorrelations are calculated, and the integral length and time scales are derived. Eulerian statistics are calculated by means of spatial and temporal analysis in order to derive characteristic length and time scales. Taylor's hypothesis of frozen turbulence is investigated, and it is found to be satisfied in the simulated flow. Lagrangian statistics are derived by tracking the trajectories of numerous particles released at different heights in the turbulent flow. The relationship between Lagrangian properties (autocorrelation functions) and dispersion characteristics (particles' displacement) is studied through Taylor's diffusion relationship, with special emphasis on the difference between horizontal and vertical motion. Results show that for the horizontal motion, Taylor's relationship is satisfied. The vertical motion, however, is influenced by the inhomogeneity of the flow and limited by the ground and the capping inversion at the top of the CBL. The Lagrangian autocorrelation function, therefore, does not have an exponential shape, and consequently, the integral time scale is zero. If distinction is made between free and bounded motion, a better agreement between Taylor's relationship and the particles' vertical displacement is found. Relationships between Eulerian and Lagrangian fr ameworks are analyzed by calculating the ratio ß between Lagrangian and Eulerian time scales. Results show that the integral time scales are mainly constant with height for z/zi <0.7. In the upper part of the CBL, the capping inversion transforms vertical motion into horizontal motion. As a result, the horizontal time scale increases with height, whereas the vertical one is reduced. Current parameterizations for the ratio between the Eulerian and Lagrangian time sca

The physical and chemical mechanisms responsible for the removal of ammonia from the atmosphere have been reviewed. Capture by atmospheric moisture (clouds, rain, fog), surface waters (rivers, lakes, seas), and deposition on vegetation and soil constitute the main pathways for ammonia removal from the troposphere. Ammonia catalyzes the atmospheric oxidation of sulfur dioxide to sulfur trioxide and reacts rapidly with acidic components of the atmosphere (sulfuric, nitric, and hydrochloric acids). The ammonium salts formed are the main components of smog aerosols and thus affect the opacity of the atmosphere and the earth radiation budget. Slow oxidation of ammonia in the atmosphere plays only a minor role in its removal. The data obtained for ammonia reactions under normal atmospheric conditions are generally applicable to model chemical reactions occurring during massive release of ammonia in the atmosphere, provided the impact of high ammonia concentration on the mass transfer processes that control some of these reactions, are taken into account., Pub. in the Jnl. of Hazardous Materials B, v108 p29-60, 2004. Prepared in collaboration with Applied Research Associates, Inc., Tyndall AFB, FL, under contract no. F08637-99-C-6004.

Experiments have been carried out under laboratory conditions to study turbulent mixing with chemical reaction. Such flows are common in the environment but there are few high-resolution measurements of them under controlled conditions. The reaction NO + O3 → NO2 + O2 + 200 kJ (mol)−1 (in the absence of UV radiation) has been used by introducing a non-buoyant reactive plume of NO into a turbulent grid flow doped with O3. The experiments have been conducted over a wide range of conditions by varying the Damko¨hler number (the ratio of the flow timescale to that of the chemical reaction) by a factor of 6 and varying the ratio of initial reactant concentrations by a factor of 30. The data are presented in two park. Part 1 (present paper) presents conventional concentration statistics. Part 2 presents concentration statistics conditionally averaged by a mixing parameter and discusses their usefulness for investigating; the reactive behaviour of the plume. Specially developed chemiluminescent analysers are used to measure NO and O3 concentrations with high-frequency response and a spatial resolution of four Kolmogorov scales (in this flow). The mixing field of the plume is studied using conserved scalar theory and is compared. to that obtained in other non-reactive flows. Results for the means, variances and joint statistics of the reactive species are presented and compared with frozen and equilibrium limits obtained from the conserved scalar theory for reacting flows. Statistics for NO show no significant trend with Damko¨hler number while those for O3 and NO2 have increased reaction at higher Damko¨hler number. The reactive scalar means are bounded by the frozen and equilibrium limits as they should be according to conserved scalar theory. Other reactive scalar statistics are not necessarily bounded by the limits. A simple relation between moments of O3 and N02 is found in the experimental results and is confirmed by conserved scalar theory. Contribution to the mean r

In this paper we present the results of two wind-tunnel simulations of dispersion from upwind point sources through a large group of obstacles, and compare these with an associated field study. Detailed flow-field and plume concentration data were obtained from simulations at scales of 1:20 and 1:200. With these data we are able to provide experimental confirmation of many of the ideas developed during the held study and to confirm the experimental results obtained in the field. In doing so, we show that the upstream flow-field parameters are the most effective means of scaling the three data sets to achieve broad quantitative agreement. Measurements and how visualisation of the flow-field confirm that there are a number of mechanisms influencing the behaviour of a plume as it passes through an obstacle array: in particular the divergence and convergence of streamlines and changes to the structure of the turbulence within the array. However, although the turbulence within the array is shown to be of greater strength and smaller scale than at corresponding locations outside the obstacle array, it is found that there is little change in the transverse diffusivity (and therefore in the lateral plume width). The concentration data confirm that the divergence of streamlines near the upstream end of the obstacle array has a significant effect on the vertical width of a plume (σ(z)). Changes to the structure of the turbulence appear to have little effect, however, since the transverse diffusivities within the obstacle array are unchanged. Thus, the mean lateral spread and decay of mean concentration of the plume with downstream distance resemble that of a control plume; that is, a plume released under identical conditions where the obstacle array is not present. We also confirm that the mean structure of a plume has a Gaussian form as it passes through an array of obstacles. By contrast, concentration measurements with a high-frequency-response detector confirm that the sm

A set of field experiments has been conducted at the Cardington experimental site, in the United Kingdom, to investigate the dispersion of a neutrally buoyant plume released upwind of an array of cubes, each of which measured approximately 2 m × 2 m × 2 m. The plume was released below the height of the obstacle array., and a second control plume was released alongside the array. The behaviour of the plume was recorded using both flow visualisation and measurements of gas concentration. A limited number of velocity measurements was also made. It is found that, relative to the control plume, certain mean concentration statistics do not change materially as the plume passes through the obstacle array. These include the form of the cross-sectional profiles, the decay along the centre line and the lateral growth with downstream distance. However, the mean vertical extent of the plume increases by 40–50%. In addition the r.m.s. fluctuations of concentration within the the plume are reduced. A clipped normal distribution is shown to be an appropriate model for the concentration fluctuations within the array plume.

A set of field experiments has been conducted at the Cardington experimental site, in the United Kingdom, to investigate the dispersion of a neutrally buoyant plume released upwind of an array of cubes, each of which measured approximately 2 m × 2 m × 2 m. The plume was released below the height of the obstacle array., and a second control plume was released alongside the array. The behaviour of the plume was recorded using both flow visualisation and measurements of gas concentration. A limited number of velocity measurements was also made. It is found that, relative to the control plume, certain mean concentration statistics do not change materially as the plume passes through the obstacle array. These include the form of the cross-sectional profiles, the decay along the centre line and the lateral growth with downstream distance. However, the mean vertical extent of the plume increases by 40–50%. In addition the r.m.s. fluctuations of concentration within the the plume are reduced. A clipped normal distribution is shown to be an appropriate model for the concentration fluctuations within the array plume.

A data base representing the results of the Lompoc Valley diffusion experiment is described in detail, outlining formats and defining the contents of the data set. Preliminary analyses are performed, showing concentrations, trajectories and plume widths of a tracer gas plume released from the Hypergolic Stockpile and Storage Facility at Vandenberg Air Force Base, California, and estimating the effects of a potential release of fuel or oxidizer. Future analysis plans are outlined.

A data base representing the results of the Lompoc Valley diffusion experiment is described in detail, outlining formats and defining the contents of the data set. Preliminary analyses are performed, showing concentrations, trajectories and plume widths of a tracer gas plume released from the Hypergolic Stockpile and Storage Facility at Vandenberg Air Force Base, California, and estimating the effects of a potential release of fuel or oxidizer. Future analysis plans are outlined, Prepared for: USAF Space Division (SSD/CLGR), Los Angeles, CA., http://archive.org/details/lompocvalleydiff00skup, MPIR FY76169000643, NA, Approved for public release; distribution is unlimited.