Atmospheric Stability Classes Research Articles

Quantifying the Daytime and Night-Time Urban Heat Island in Birmingham, UK: A Comparison of Satellite Derived Land Surface Temperature and High Resolution Air Temperature Observations

The Urban Heat Island (UHI) is one of the most well documented phenomena in urban climatology. Although a range of measurements and modelling techniques can be used to assess the UHI, the paucity of traditional meteorological observations in urban areas has been an ongoing limitation for studies. The availability of remote sensing data has therefore helped fill a scientific need by providing high resolution temperature data of our cities. However, satellite-mounted sensors measure land surface temperatures (LST) and not canopy air temperatures with the latter being the key parameter in UHI investigations. Fortunately, such data is becoming increasingly available via urban meteorological networks, which now provide an opportunity to quantify and compare surface and canopy UHI on an unprecedented scale. For the first time, this study uses high resolution air temperature data from the Birmingham Urban Climate Laboratory urban meteorological network and MODIS LST to quantify and identify the spatial pattern of the daytime and night-time UHI in Birmingham, UK (a city with an approximate population of 1 million). This analysis is performed under a range of atmospheric stability classes and investigates the relationship between surface and canopy UHI in the city. A significant finding of this work is that it demonstrates, using observations, that the distribution of the surface UHI appears to be clearly linked to landuse, whereas for canopy UHI, advective processes appear to play an increasingly important role. Strong relationships were found between air temperatures and LST during both the day and night at a neighbourhood scale, but even with the use of higher resolution urban meteorological datasets, relationships at the city scale are still limited.

Radiation Dose Calculations for a Hypothetical Accident in Xianning Nuclear Power Plant

Atmospheric dispersion modeling and radiation dose calculations have been performed for a hypothetical AP1000 SGTR accident by HotSpot code 3.03. TEDE, the respiratory time-integrated air concentration, and the ground deposition are calculated for various atmospheric stability classes, Pasquill stability categories A–F with site-specific averaged meteorological conditions. The results indicate that the maximum plume centerline ground deposition value of1.2E+2 kBq/m2occurred at about 1.4 km and the maximum TEDE value of1.41E-05 Sv occurred at 1.4 km from the reactor. It is still far below the annual regulatory limits of 1 mSv for the public as set in IAEA Safety Report Series number 115. The released radionuclides might be transported to long distances but will not have any harmful effect on the public.

Estimation of Appropriate Stack Height at Industrial Layout, Makurdi, Benue State

The prediction of appropriate stack height at the Makurdi industrial layout in Benue State of Nigeria is carried out using the point source Gaussian plume model. The model takes into account the ambient environmental conditions and emission source parameters to calculate and estimate the appropriate stack height for three prevailing atmospheric stability classes, A, D and F within the Makurdi Industrial layout. The research estimates an appropriate stack height of ~65.0m for the Makurdi industrial layout. The results set a baseline for environmental safety standards for industries operating at the industrial layout and can be adopted by the National Environmental Standard Enforcement and Regulatory Agency (NESERA), and other concerned authorities in environmental monitoring and pollution control.

Quantificação da ilha de calor de curitiba considerando aspectos de estabilidade atmosférica

RESUMO A relação entre crescimento urbano e o surgimento de ilhas de calor urbanas, ou seja, diferenças climáticas entre a área urbana e as áreas rurais no entorno, é demonstrada por diversos autores e em diferentes regiões climáticas. Em Curitiba, a população saltou de aproximadamente 600.000 habitantes para um milhão e meio em três décadas. O objetivo do presente trabalho é propor uma metodologia de análise da ilha de calor urbana de Curitiba (25º25'40"S, 49º16'23"W, 934m acima do nível do mar). A cidade está localizada em região de clima subtropical de altitude; o monitoramento climático foi conduzido segundo uma série anual, entre dezembro de 2011 e fevereiro de 2013, utilizando um par de estações meteorológicas dentro e fora (perifericamente) da mancha urbana de Curitiba. De modo a minimizar possíveis influências atmosféricas na análise, foi feita a classificação dos dias de medição por classes de estabilidade atmosférica segundo o método de Pasquill-Gifford-Turner (PGT), procedendo-se à análise para dias com maior estabilidade atmosférica. Como complemento à análise, adota-se um modelo de conforto desenvolvido para Curitiba a partir de uma extensa pesquisa de sensação e percepção térmicas em espaços abertos, de modo a verificar o efeito integrado das diversas variáveis climáticas em termos de percentuais de horas em frio, conforto e calor e suas variações dentro e fora da área urbana. Em Curitiba, a ilha de calor urbana pode ser benéfica durante o inverno, porém trazendo consequências em termos de excesso de calor em ambientes internos no verão.

Optimisation of dispersion parameters of Gaussian plume model for CO₂ dispersion.

The carbon capture and storage (CCS) and enhanced oil recovery (EOR) projects entail the possibility of accidental release of carbon dioxide (CO2) into the atmosphere. To quantify the spread of CO2 following such release, the 'Gaussian' dispersion model is often used to estimate the resulting CO2 concentration levels in the surroundings. The Gaussian model enables quick estimates of the concentration levels. However, the traditionally recommended values of the 'dispersion parameters' in the Gaussian model may not be directly applicable to CO2 dispersion. This paper presents an optimisation technique to obtain the dispersion parameters in order to achieve a quick estimation of CO2 concentration levels in the atmosphere following CO2 blowouts. The optimised dispersion parameters enable the Gaussian model to produce quick estimates of CO2 concentration levels, precluding the necessity to set up and run much more complicated models. Computational fluid dynamics (CFD) models were employed to produce reference CO2 dispersion profiles in various atmospheric stability classes (ASC), different 'source strengths' and degrees of ground roughness. The performance of the CFD models was validated against the 'Kit Fox' field measurements, involving dispersion over a flat horizontal terrain, both with low and high roughness regions. An optimisation model employing a genetic algorithm (GA) to determine the best dispersion parameters in the Gaussian plume model was set up. Optimum values of the dispersion parameters for different ASCs that can be used in the Gaussian plume model for predicting CO2 dispersion were obtained.

Dose assessment of radionuclides dispersion from Bushehr nuclear power plant stack under normal operation and accident conditions

Assessment of individual and collective doses around the unit-1 of Bushehr nuclear power plant (BNPP-1) site during normal nuclear reactor operation and under reactor accident conditions which are essential for safety and environmental analyses is presented in this paper. Release of radioactive materials to the environment following a design basic accident (DBA) (e.g. LBLOCA) is evaluated using HOTSPOT health physics computer code. In the normal operation conditions, atmospheric dispersion of radioactive material is calculated using CAP88-PC code. These codes utilize a Gaussian dispersion air transport plume model to simulate the atmospheric dispersion of radionuclides in different atmospheric stability classes and various wind speeds and directions. To calculate the doses under normal operation using CAP88 code, the surrounding area of the BNPP-1 within a radius of 30 km is gridded into 12 concentric rings and 16 sectors and the distribution of population and data of agricultural products are calculated for each grid. The meteorological data on atmospheric stability conditions, wind speed and the frequency distribution of wind direction based on data collected near the reactor site are also analyzed and applied. The results illustrate that the maximum total effective dose equivalent (TEDE) and committed effective dose equivalent (CEDE) values for personnel and public around the BNPP-1 site are lower than the annual effective dose limits for workers and public in normal operation and under accident conditions. Also, the results of the radiological impacts of the BNPP-1 in normal and accidental radioactive materials releases are compared with the dose values given in the Final Safety Analysis Report (FSAR) of the BNPP-1.

Modeling Short-Term Maximum Individual Exposure from Airborne Hazardous Releases in Urban Environments. Part I: Validation of a Deterministic Model with Field Experimental Data.

The release of airborne hazardous substances in the atmosphere has a direct effect on human health as, during the inhalation, an amount of concentration is inserted through the respiratory system into the human body, which can cause serious or even irreparable damage in health. One of the key problems in such cases is the prediction of the maximum individual exposure. Current state of the art methods, which are based on the concentration cumulative distribution function and require the knowledge of the concentration variance and the intermittency factor, have limitations. Recently, authors proposed a deterministic approach relating maximum individual exposure to parameters such as the fluctuation intensity and the concentration integral time scale. The purpose of the first part of this study is to validate the deterministic approach with the extensive dataset of the MUST (Mock Urban Setting Test) field experiment. This dataset includes 81 trials, which practically cover various atmospheric conditions and stability classes and contains in total 4004 non-zero concentration sensor data with time resolutions of 0.01–0.02 s. The results strengthen the usefulness of the deterministic model in predicting short-term maximum individual exposure. Another important output is the estimation of the methodology uncertainty involved.

Опасность взрыва облака биогаза, образующегося на полигонах твердых бытовых отходов

Analysis of negative factors of solid waste (SW) landfills seldom includes explosion hazard of a biogas cloud formed by
 degradation of organic part of waste. The article analyses dynamics of biogas generation depending on characteristics of
 waste pre-sorting, gas-air cloud (GAC) distribution considering SW landfill lifetime, season and atmospheric stability class.
 Deflagration explosion poses actual danger of buildings destruction and life loss in settlements adjacent to the landfill.
 GAC explosion frequency rate is estimated 7,87 · 10–6 per year.

Modelling plume dispersion pattern from a point source using spatial auto-correlational analysis

The main objective of the study is to estimate the rate and model the pattern of plume rise from Dangote Cement Plc. A handheld Garmin GPS was employed for collection of coordinates at a single kilometre graduation from the centre of the factory to 10 kilometres. Plume rate was estimated using the Gaussian model while Kriging, using ArcGIS, was adopted for modelling the pattern of plume dispersion over a 10 kilometre radius around the factory. ANOVA test was applied for statistical analysis of the plume coefficients. The results indicate that plume dispersion is generally high with highest values recorded for the atmospheric stability classes A and B, while the least values are recorded for the atmospheric stability classes F and E. The variograms derived from the Kriging reveal that the pattern of plume dispersion is outwardly radial and omni-directional. With the exception of 3 stability sub-classes (DH, EH and FH) out of a total of 12, the 24-hour average of particulate matters (PM10 and PM2.5) within the study area is outrageously higher (highest value at 21392.3) than the average safety limit of 150 ug/m3 – 230 ug/m3 prescribed by the 2006 WHO guidelines. This indicates the presence of respirable and non-respirable pollutants that create poor ambient air quality. The study concludes that the use of geospatial technology can be adopted in modelling dispersion of pollutants from a point source. The study recommends ameliorative measures to reduce the rate of plume emission at the factory.

Radiation dose calculations for an accidental release from the Tehran Research Reactor

Radiological consequence analysis is carried out for a postulated accidental airborne radionuclide release from the Tehran Research Reactor (TRR). Using the “Hots pot” computer code, Total Effective Dose Equivalent (TEDE) values to the public for various atmospheric stability classes are calculated as a function of downwind distances. Base on these estimates, critical exposure zone around the reactor is categorized.

Suspended Particulates Concentration (PM10) under Unstable Atmospheric Conditions over Subtropical Urban Area (Qena, Egypt)

The main purpose of this study is to evaluate the suspended particulates (PM10) in the atmosphere under unstable atmospheric conditions. The variation of PM10was investigated and primary statistics were employed. The results show that, the PM10concentrations values ranged from 6.00 to 646.74 μg m−3. The average value of PM10is equal to 114.32 μg m−3. The high values were recorded in April and May (155.17 μg m−3and 171.82 μg m−3, respectively) and the low values were noted in February and December (73.86 μg m−3and 74.05 μg m−3, respectively). The average value of PM10of the hot season (125.35 × 10−6 g m−3) was higher than its value for the cold season (89.27 μg m−3). In addition, the effect of weather elements (air temperature, humidity and wind) on the concentration of PM10was determined. The multiple R between PM10and these elements ranged from 0.05 to 0.47 and its value increased to reach 0.73 for the monthly average of the database used. Finally, the PM10concentrations were grouped depending on their associated atmospheric stability class. These average values were equal to 122.80 ± 9 μg m−3(highly unstable or convective), 109.37 ± 12 μg m−3(moderately unstable) and 104.42 ± 15 μg m−3(slightly unstable).

Impact of downwind sampling location and height on inverse-Gaussian dispersion modeling: A theoretical study

In the studies of fate and transport of air emissions from animal feeding operations, Gaussian based dispersion models have been commonly used to predict downwind pollutant concentrations through forward modeling approach, or to derive emission rates and emission factors through inverse dispersion modeling approach. In the Gaussian dispersion modeling process, downwind sampling location and sampling height could generate significant impact on accuracy of the model validation, or inverse modeling results based upon field measurements. This study theoretically analyzed the impact of downwind locations and sampling height on Gaussian dispersion modeling. It was discovered that the field sampling needs to be conducted at the locations beyond the plume touching-ground distance, at a downwind distance as short as 5 m for the case scenario with zero rise of emission plume under the atmospheric stability class C, or as long as 297 m for the case scenario with 15 m rise of emission plume under the atmospheric stability class F. In order to measure the PM concentrations of the dispersion plume, the minimum sampling height at the locations within the plume touching-ground distance varied from ground level to as high as almost 14 m, whereas for the locations beyond the plume touching-ground distance, a sampling height of ground level would be acceptable.

Assessment of the total effective dose equivalent for accidental release from the Tehran Research Reactor

Assessment of the population total effective dose equivalent (TEDE) around the reactor sites during both normal nuclear reactor operation and under reactor accident conditions is essential for the safety and environmental analyses that are needed for reactor licensing. Estimation of the radionuclide atmospheric dispersion and TEDE need utilization of validated atmospheric dispersion models.In this study, the TEDE that will be received by the surrounding population as a result of radionuclide release from the 5MW Tehran Research Reactor following a hypothetical accident has been calculated using HOTSPOT health physics computer code developed at Lawrence Livermore National Laboratory, University of California, USA. The HOTSPOT 2.07 code uses a Gaussian plume model to simulate the radionuclide atmospheric dispersion for atmospheric stability classes (A–F), different wind speeds at various downwind distances up to 100km from the reactor site.The computational results show that the maximum TEDE values for personnel and public around the TRR site are lower than the annual effective dose limits for worker and population under the assumed accidental condition. Therefore, based on well-known procedures presented in the regulatory guide we can conclude that the standards of safety are reasonably achieved in the TRR site.

Dispersion modeling and health risk assessment of dioxin emissions from a municipal solid waste incinerator in Hangzhou, China

The emission of dioxins from municipal solid waste incinerators (MSWIs) has become a widespread concern. The effect of meteorological parameters (wind speed, atmospheric stability and mixing height) on the hourly ground level concentration (GLC) of dioxins was estimated using air dispersion models. Moreover, the health risks of dioxin exposure were evaluated for children and adults using the Nouwen equation. The total environmental exposure via air inhalation and food ingestion was calculated, based on linear fit equations. The results indicate that potentially severe pollution from dioxins occurs at a wind speed of 1.5 m/s with atmospheric stability class F. In addition, local residents in the study area are exposed to severe weather conditions most of the time, and the risk exposures for children are far higher than those for adults. The total exposure for children far exceeds the tolerable daily intake of dioxin recommended by the World Health Organization (WHO) of 1–4 pg TEQ/(kg·d) under severe weather conditions. Results from modeling calculations of health risk assessment were consistent with dioxin levels obtained during actual monitoring of emissions.

Sensitivity analysis of Phast’s atmospheric dispersion model for three toxic materials (nitric oxide, ammonia, chlorine)

We present the results of a parametric sensitivity analysis of a widely used model for atmospheric dispersion of toxic gases, in order better to understand the influence of user-adjustable parameters on model outputs. We have studied 60 min continuous release scenarios for three different products (nitric oxide, ammonia and chlorine), chosen to cover a range of physical characteristics and storage conditions. For each product, we have broken down base-case scenarios into a number of sub-scenarios corresponding to different release conditions which determine physical phenomena (flow rate, release angle, release elevation and atmospheric stability class). The use of statistical tools to analyze the results of a large number of model executions allows us to rank model parameters according to their influence on the variability of a number of model outputs (distances and concentrations), on a per-scenario and per-product basis. Analysis of the results allows us to verify our understanding of the modeling of cloud dispersion.

Chlorine Truck Attack Consequences and Mitigation

We develop and apply an integrated modeling system to estimate fatalities from intentional release of 17 tons of chlorine from a tank truck in a generic urban area. A public response model specifies locations and actions of the populace. A chemical source term model predicts initial characteristics of the chlorine vapor and aerosol cloud. An atmospheric dispersion model predicts cloud spreading and movement. A building air exchange model simulates movement of chlorine from outdoors into buildings at each location. A dose-response model translates chlorine exposures into predicted fatalities. Important parameters outside defender control include wind speed, atmospheric stability class, amount of chlorine released, and dose-response model parameters. Without fast and effective defense response, with 2.5 m/sec wind and stability class F, we estimate approximately 4,000 (half within ∼10 minutes) to 30,000 fatalities (half within ∼20 minutes), depending on dose-response model. Although we assume 7% of the population was outdoors, they represent 60-90% of fatalities. Changing weather conditions result in approximately 50-90% lower total fatalities. Measures such as sheltering in place, evacuation, and use of security barriers and cryogenic storage can reduce fatalities, sometimes by 50% or more, depending on response speed and other factors.

Mathematical Modeling for Atmospheric Dispersion of Radioactive Cloud Passing Over Jeddah

Atmospheric dispersion has been performed for a hypothetical accidental airborne radionuclide release from any nuclear installation such as power reactor, research reactor or any facility which uses radioisotopes as its tools. Estimate of release for various radionuclides are based on U.S Nuclear Regulatory Commission (NRC 1.183). The normalized concentration distribution (NCD) of pollutants is calculated as a function of downwind horizontal distance up to 10 km from the release point. These estimates have been performed for Jeddah city (Kingdom of Saudi Arabia) using Gaussian Plume Model (GPM). The calculations have been evaluated for the atmospheric thermal stability class , B , (moderately unstable), which is, meteorologically, and according to Pasquill classification, the dominant stability category for Jeddah city. The computer program Mathmatica is used for this purpose. Also, the effect of radioactive decay on The NCD of pollutants has been investigated. The relevant meteorological data, namely, atmospheric thermal stability class, mean wind speed and direction and their frequency of occurrence for Jeddah city have been analyzed and presented . The results indicate that the NCD is significantly affected by the radioactive decay factor, particularly, in cases of short- lived isotopes, where It reduces the concentration of cloud by different ratios depending on the half- life time of a radionuclide.

Characterization of atmospheric contaminant sources using adaptive evolutionary algorithms

The characteristics of an unknown source of emissions in the atmosphere are identified using an Adaptive Evolutionary Strategy (AES) methodology based on ground concentration measurements and a Gaussian plume model. The AES methodology selects an initial set of source characteristics including position, size, mass emission rate, and wind direction, from which a forward dispersion simulation is performed. The error between the simulated concentrations from the tentative source and the observed ground measurements is calculated. Then the AES algorithm prescribes the next tentative set of source characteristics. The iteration proceeds towards minimum error, corresponding to convergence towards the real source. The proposed methodology was used to identify the source characteristics of 12 releases from the Prairie Grass field experiment of dispersion, two for each atmospheric stability class, ranging from very unstable to stable atmosphere. The AES algorithm was found to have advantages over a simple canonical ES and a Monte Carlo (MC) method which were used as benchmarks.

Seasonality in onshore normalized wind profiles above the surface layer

Abstract. This work aims to study the seasonal difference in normalized wind speed above the surface layer as it is observed at the 160 m high mast at the coastal site Høvsøre at winds from the sea (westerly). Normalized and stability averaged wind speeds above the surface layer are observed to be 20 to 50% larger in the winter/spring seasons compared to the summer/autumn seasons at winds from west within the same atmospheric stability class. A method combining the mesoscale model, COAMPS, and observations of the surface stability of the marine boundary layer is presented. The objective of the method is to reconstruct the seasonal signal in normalized wind speed and identify the physical process behind. The method proved reasonably successful in capturing the relative difference in wind speed between seasons, indicating that the simulated physical processes are likely candidates to the observed seasonal signal in normalized wind speed.

Uncertainties Associated with the Use of Optical Remote Sensing Technique to Estimate Surface Emissions in Landfill Applications

Landfills represent a source of distributed emissions source over an irregular and heterogeneous surface. In the method termed “Other Test Method-10” (OTM-10), the U.S. Environmental Protection Agency (EPA) has proposed a method to quantify emissions from such sources by the use of vertical radial plume mapping (VRPM) techniques combined with measurement of wind speed to determine the average emission flux per unit area per time from nonpoint sources. In such application, the VRPM is used as a tool to estimate the mass of the gas of interest crossing a vertical plane. This estimation is done by fitting the field-measured concentration spatial data to a Gaussian or some other distribution to define a plume crossing the vertical plane. When this technique is applied to landfill surfaces, the VRPM plane may be within the emitting source area itself. The objective of this study was to investigate uncertainties associated with using OTM-10 for landfills. The spatial variability of emission in the emitting domain can lead to uncertainties of –34 to 190% in the measured flux value when idealistic scenarios were simulated. The level of uncertainty might be higher when the number and locations of emitting sources are not known (typical field conditions). The level of uncertainty can be reduced by improving the layout of the VRPM plane in the field in accordance with an initial survey of the emission patterns. The change in wind direction during an OTM-10 testing setup can introduce an uncertainty of 20% of the measured flux value. This study also provides estimates of the area contributing to flux (ACF) to be used in conjunction with OTM-10 procedures. The estimate of ACF is a function of the atmospheric stability class and has an uncertainty of 10–30%.