Journal of Atmospheric and Solar-Terrestrial Physics, 2013
We investigate mass transfer during absorption of highly soluble gases such as HNO 3 , H 2 O 2 by... more We investigate mass transfer during absorption of highly soluble gases such as HNO 3 , H 2 O 2 by stagnant cloud droplets in the presence of inert admixtures. Thermophysical properties of the gases and liquids are assumed to be constant. Diffusion interactions between droplets, caused by the overlap of depleted of soluble gas regions around the neighboring droplets, are taken into account in the approximation of a cellular model of a gas-droplet suspension whereby a suspension is viewed as a periodic structure consisting of the identical spherical cells with periodic boundary conditions at the cell boundary. Using this model we determined temporal and spatial dependencies of the concentration of the soluble trace gas in a gaseous phase and in a droplet and calculated the dependence of the scavenging coefficient on time. We found that scavenging coefficient for gas absorption by cloud droplets remains constant and sharply decreases only at the final stage of absorption. In the calculations we employed a Monte Carlo method and assumed gamma size distribution of cloud droplets. It is shown that despite of the comparable values of Henry's law constants for the hydrogen peroxide (H 2 O 2 ) and the nitric acid (HNO 3 ), the nitric acid is scavenged more effectively by cloud droplets than the hydrogen peroxide due to a major affect of the dissociation reaction on HNO 3 scavenging. It is demonstrated that scavenging of highly soluble gases by cloud droplets leads to strong decrease of soluble trace gas concentration in the interstitial air. We obtained also analytical expressions for the ''equilibrium values'' of concentration of the soluble trace gas in a gaseous phase and for concentration of the dissolved gas in a liquid phase for the case of hydrogen peroxide and nitric acid absorption by cloud droplets.
Recent advances in understanding of the surface energy balance of urban areas, based on both expe... more Recent advances in understanding of the surface energy balance of urban areas, based on both experimental investigations andnumerical models, are reviewed. Particular attention is directedto the outcome of a COST-715 Expert Meeting held in April 2000, as well as experiments initiated by that action. In addition, recentcomplete parameterisations of urban effects in meso-scalemodels are reviewed. Given that neither the surface energybalance, nor its components, normally are directly measuredat meteorological stations, nor are ...
This study reviews the top ranked meteorology and chemistry interactions in online coupled 32 mod... more This study reviews the top ranked meteorology and chemistry interactions in online coupled 32 models recommended by an experts' survey conducted in COST Action EuMetChem and 33 examines the sensitivity of those interactions during two pollution episodes: the Russian forest 34 fires 25 Jul -15 Aug 2010 and a Saharan dust transport event from 1 Oct -31 Oct 2010 as a part of 35 the AQMEII phase-2 exercise. Three WRF-Chem model simulations were performed for the 36 forest fire case for a baseline without any aerosol feedback on meteorology, a simulation with 37 aerosol direct effects only and a simulation including both direct and indirect effects. For the dust 38 case study, eight WRF-Chem and one WRF-CMAQ simulations were selected from the set of 39 simulations conducted in the framework of AQMEII. Of these two simulations considered no 40 feedbacks, two included direct effects only and five simulations included both direct and indirect 41 effects. The results from both episodes demonstrate that it is important to include the 42 meteorology and chemistry interactions in online-coupled models. Model evaluations using 43 routine observations collected in AQMEII phase-2 and observations from a station in Moscow 44 show that for the fire case the simulation including only aerosol direct effects has better 45 performance than the simulations with no aerosol feedbacks or including both direct and indirect 46 effects. The normalized mean biases are significantly reduced by 10-20% for PM10 when 47 including aerosol direct effects. The analysis for the dust case confirms that models perform 48 better when including aerosol direct effects, but worse when including both aerosol direct and 49 indirect effects, which suggests that the representation of aerosol indirect effects needs to be 50 improved in the model. 51 52 M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT Key words: aerosol direct effects, feedback, PM10, fire and dust 1 2 Highlights 3 4
Meteorological and Air Quality Models for Urban Areas, 2009
Many urban surface energy balance models now exist. These vary in complexity from simple schemes ... more Many urban surface energy balance models now exist. These vary in complexity from simple schemes that represent the city as a concrete slab, to those which incorporate detailed representations of momentum and energy fluxes distributed within the atmospheric boundary layer. While many of these schemes have been evaluated against observations, with some models even compared with the same data sets, such evaluations have not been undertaken in a controlled manner to enable direct comparison. For other types of climate model, for instance the Project for Intercomparison of Land-Surface Parameterization Schemes (PILPS) experiments , such controlled comparisons have been shown to provide important insights into both the mechanics of the models and the physics of the real world. This paper describes the progress that has been made to date on a systematic and controlled comparison of urban surface schemes. The models to be considered, and their key attributes, are described, along with the methodology to be used for the evaluation.
Ulaanbaatar, the capital city of Mongolia is subject to high air particulate matter pollution epi... more Ulaanbaatar, the capital city of Mongolia is subject to high air particulate matter pollution episodes during winter and during dust storm events in spring and autumn that have severe implications for the health of the exposed population. This paper presents the results of fine (PM2. 5) and coarse (PM10–2.5) particulate matter monitoring in Ulaanbaatar from 2004 to 2008 and receptor modelling to determine the sources contributing to particulate matter pollution. Ion Beam Analysis was used to determine elemental ...
The size distribution of aerosols containing metal was investigated in the Monchegorsk region. It... more The size distribution of aerosols containing metal was investigated in the Monchegorsk region. It was found that lead and arsenic occur predominantly in fine particles ( < 1 pm) and that copper and nickel occur both in fine (< 1 pm) and coarse particles. The mean ratios of total mass (all size ranges) Cu/Pb and Cu/As in the air were found to be 10 and 16, respectively. Comparing these ratios with the snowpack data of Jaffe et al. (1994) in the Monchegorsk region, we find an enhancement of Cu in the snowpack, relative to Pb and As. This is consistent with our observed size distributions and indicates that the Monchegorsk Pb and As emissions are transported longer distances than Cu and Ni prior to removal. Results show the importance of considering the size distribution of metal emissions in chemical transport and/or factor analysis type models.
Snowpack samples were collected at 20 sites on the Kola Peninsula, Russia, in April 1991. Samples... more Snowpack samples were collected at 20 sites on the Kola Peninsula, Russia, in April 1991. Samples were collected both in remote regions and in areas impacted by nearby emission sources, including the Severonikel Cu-Ni smelter in the city of Monchegorsk. In the background regions, total winter deposition for non-seasalt SO:-, NO;, Cu, and Ni were 120-300, 70-300, 6-14, and 0.3-M mg/m2, respectively, and the snowpack pH ranged from 4.4 to 4.9. In the region near the Severonikel Cu-Ni smelter, snowpack SO:-, Cu, and Ni concentrations were enhanced considerably.
Physics and Chemistry of the Earth, Part B: Hydrology, Oceans and Atmosphere, 2001
Radionuclides are released into the atmosphere in the form of gases or aerosols. The aerosols hav... more Radionuclides are released into the atmosphere in the form of gases or aerosols. The aerosols have different particle sizes (0.01-60 Ixm). This paper analyses parameterisations of the removal processes by dry and wet deposition of radionuclides to the ground, and recommends some parameterisations and their realisation for the DERMA model as an example. It is shown that the washout coefficient strongly depends on the particle size. This dependence, however, is not included in most atmospheric dispersion models. Therefore, a revised formulation of the wet deposition parameterisation for particles of different size is suggested. The effect of gravitational settling is included in the dry deposition parameterisation by a combination of Stokes' law with the Cunningham correction for small particles and an iterative procedure solving the differential equation for the terminal settling velocity for large particles. Comparisons of simulation results for the Algeciras accident, Spain, with measurement data from the European monitoring network are presented and discussed.
Regional air pollution models are usually off-line coupled with numerical weather prediction mode... more Regional air pollution models are usually off-line coupled with numerical weather prediction models. The present study, however, focuses on on-line coupled modelling, for which the air pollution model is an integral part of the meteorological model. To this purpose, simulations of the first European Tracer Experiment (ETEX), which supplies the best suited verification data for dispersion modelling of a passive tracer, have been performed using versions of the Danish Meteorological Institute High Resolution Limited-Area Model (DMI-HIRLAM). Simulation results have been compared with observed values as well as with results from other models.
The three-dimensional atmospheric dispersion model DERMA is of Lagrangian type making use of a hy... more The three-dimensional atmospheric dispersion model DERMA is of Lagrangian type making use of a hybrid stochastic particle-puff diffusion description. It is currently capable of describing plumes at downwind distances greater than about 20 km and up to the global scale. The model employs aerosolsize dependent dry and wet deposition parameterisations. DERMA is developed and used mainly for nuclear emergency preparedness purposes, and it has recently become integrated with the ARGOS nuclear decision-support system.
KEYWORDS diffusion battery, aerosol generators, size distribution, CPC, ADB As a result of fundam... more KEYWORDS diffusion battery, aerosol generators, size distribution, CPC, ADB As a result of fundamental researches of photo -induced nucleation, we have designed a set of photochemical -type of aerosol generators for testing the sensitivity and size resolution of different types of aerosols counters. The set covers particles size range from 2 to 1OO nm, and concentration rangeup to 107 particles/cc. It consists of three generators. The first two generators produce metal ,oxide (WO and MoO ) particx ~ x 7 3 les with number concentration (N a) in the range IO J -10" cm--, particles diameter (alp)-from 2 to 10 nm, standard geometric deviation (o s) is about I .4. The third one is photochemical generator, based on haloidaromatic compounds photolysis [1 ]. Na 105 + 107 cm -3, size range -from 2 to 100 nm in diameter, o -1.2 -1.6, depending on d .
Environmental Science and Pollution Research, 2013
There is extensive evidence of the negative impacts on health linked to the rise of the regional ... more There is extensive evidence of the negative impacts on health linked to the rise of the regional background of PM10 levels. These levels are often increased over urban areas becoming one of the main air pollution concerns. This is the case on the Bilbao metropolitan area, Spain. This study describes a data-driven model to diagnose PM10 levels in Bilbao at hourly intervals. The model is built with a training period of sevenyear historical data covering different urban environments (inland, city centre and coastal sites). The explanatory variables are quantitative -log [NO2], temperature, short-wave incoming radiation, wind speed and direction, specific humidity, hour and vehicle intensity -and qualitative -working days/weekends, season (winter/summer), the hour (from 00 to 23 UTC) and precipitation/no precipitation. Three different linear regression models are compared: simple linear regression (LIN); linear regression with interaction terms (INT) and linear regression with interaction terms following the Sawa's Bayesian Information Criteria (INT-BIC). Each type of model is calculated selecting two different periods: the training (it consists on 6 years) and the testing dataset (it consists on 1 year). The results of each type of model shows that the INT-BIC based model (R2 = 0.42) is the best. Results were R of 0.65, 0.63 and 0.60 for the city centre, inland and coastal sites, respectively, a level of confidence similar to the state-of-the art in the methodology. The error related calculated for longer time intervals (monthly or seasonal means) diminished significantly (R of 0.75-0.80 for monthly means and R of 0.80 to 0.98 at seasonally means) with respect to shorter periods
The main focus of this paper is the description of a methodology for probabilistic or long-term e... more The main focus of this paper is the description of a methodology for probabilistic or long-term evaluation of the atmospheric transport and deposition of harmful (for example radioactive) releases from risk sites based on a dispersion modelling approach. This work was realised as a part of the multidisciplinary 'Arctic Risk' study; the purpose of which was the development of a methodology for environmental risk and vulnerability assessments and the testing of this methodology through estimation of the nuclear risk to the population in the Northern European countries in case of a severe accident at a nuclear risk site. The following research tools were applied for probabilistic atmospheric studies:
Traditionally, transport and dispersion models are offline coupled to meteorological drivers, rec... more Traditionally, transport and dispersion models are offline coupled to meteorological drivers, receiving pre-processed output at regular coupling intervals. However, today meteorological models have reached urban and cloud resolving scales and online models integrating meteorological and dispersion models have been developed. In this study the online coupled model, Enviro-HIRLAM, which can also run in offline mode, was used to compare online and offline representations of meso-scale disturbances. The online model was evaluated using data from the first European Tracer Experiment (ETEX-1) and produced satisfactory results. Meso-scale influences during the simulation pertube the plume during long-range transport, leading to a double peak structure at a specific measurement station. The mesoscale influence was investigated by varying the offline coupling interval which was shown to be important in constraining the influence of meso-scale disturbances on plume structure in coarse resolution.
The increased resolution of numerical weather prediction models allows nowadays addressing more r... more The increased resolution of numerical weather prediction models allows nowadays addressing more realistically urban meteorology and air pollution processes. This has triggered new interest in modelling and describing experimentally the specific features and processes of urban areas. Recent developments and results performed within the EU-funded project FUMAPEX on integrated systems for forecasting urban meteorology and air pollution are reported here. Sensitivity studies with respect to optimum resolution, parametrisation of urban roughness and surface exchange fluxes and the role of urban soil layers are carried out with advanced meso-or sub-meso meteorological models. They show that sensible improvements can be achieved by higher model resolution that is accompanied with better description of urban surface features. Recommendations, especially with respect to advanced urban air quality forecasting and information systems, are given together with an assessment of the needed further research and data.
The quality of the urban air pollution forecast critically depends on the mapping of emissions, t... more The quality of the urban air pollution forecast critically depends on the mapping of emissions, the urban air pollution models, and the meteorological data. The quality of the meteorological data should be largely enhanced by using downscaled data from advanced numerical weather prediction models. These different topics, as well as the application of population exposure models, have traditionally been treated in distinct scientific communities whose expertise needs to be combined to enhance the possibilities of forecasting air pollution episodes in European cities. For this purpose the EU project "Integrated Systems for Forecasting Urban Meteorology, Air Pollution and Population Exposure" (FUMAPEX) (http://fumapex.dmi.dk), involving 22 organizations from 10 European countries, was initiated. The main objectives of the project are the improvement of meteorological forecasts for urban areas, the connection of numerical weather prediction models to urban air pollution and population exposure models, the building of improved Urban Air Quality Information and Forecasting Systems, and their application in cities in various European climates. This paper overviews the project items and first two-years results, it is an introduction to the whole ACP issue.
Journal of Atmospheric and Solar-Terrestrial Physics, 2013
We investigate mass transfer during absorption of highly soluble gases such as HNO 3 , H 2 O 2 by... more We investigate mass transfer during absorption of highly soluble gases such as HNO 3 , H 2 O 2 by stagnant cloud droplets in the presence of inert admixtures. Thermophysical properties of the gases and liquids are assumed to be constant. Diffusion interactions between droplets, caused by the overlap of depleted of soluble gas regions around the neighboring droplets, are taken into account in the approximation of a cellular model of a gas-droplet suspension whereby a suspension is viewed as a periodic structure consisting of the identical spherical cells with periodic boundary conditions at the cell boundary. Using this model we determined temporal and spatial dependencies of the concentration of the soluble trace gas in a gaseous phase and in a droplet and calculated the dependence of the scavenging coefficient on time. We found that scavenging coefficient for gas absorption by cloud droplets remains constant and sharply decreases only at the final stage of absorption. In the calculations we employed a Monte Carlo method and assumed gamma size distribution of cloud droplets. It is shown that despite of the comparable values of Henry's law constants for the hydrogen peroxide (H 2 O 2 ) and the nitric acid (HNO 3 ), the nitric acid is scavenged more effectively by cloud droplets than the hydrogen peroxide due to a major affect of the dissociation reaction on HNO 3 scavenging. It is demonstrated that scavenging of highly soluble gases by cloud droplets leads to strong decrease of soluble trace gas concentration in the interstitial air. We obtained also analytical expressions for the ''equilibrium values'' of concentration of the soluble trace gas in a gaseous phase and for concentration of the dissolved gas in a liquid phase for the case of hydrogen peroxide and nitric acid absorption by cloud droplets.
Recent advances in understanding of the surface energy balance of urban areas, based on both expe... more Recent advances in understanding of the surface energy balance of urban areas, based on both experimental investigations andnumerical models, are reviewed. Particular attention is directedto the outcome of a COST-715 Expert Meeting held in April 2000, as well as experiments initiated by that action. In addition, recentcomplete parameterisations of urban effects in meso-scalemodels are reviewed. Given that neither the surface energybalance, nor its components, normally are directly measuredat meteorological stations, nor are ...
This study reviews the top ranked meteorology and chemistry interactions in online coupled 32 mod... more This study reviews the top ranked meteorology and chemistry interactions in online coupled 32 models recommended by an experts' survey conducted in COST Action EuMetChem and 33 examines the sensitivity of those interactions during two pollution episodes: the Russian forest 34 fires 25 Jul -15 Aug 2010 and a Saharan dust transport event from 1 Oct -31 Oct 2010 as a part of 35 the AQMEII phase-2 exercise. Three WRF-Chem model simulations were performed for the 36 forest fire case for a baseline without any aerosol feedback on meteorology, a simulation with 37 aerosol direct effects only and a simulation including both direct and indirect effects. For the dust 38 case study, eight WRF-Chem and one WRF-CMAQ simulations were selected from the set of 39 simulations conducted in the framework of AQMEII. Of these two simulations considered no 40 feedbacks, two included direct effects only and five simulations included both direct and indirect 41 effects. The results from both episodes demonstrate that it is important to include the 42 meteorology and chemistry interactions in online-coupled models. Model evaluations using 43 routine observations collected in AQMEII phase-2 and observations from a station in Moscow 44 show that for the fire case the simulation including only aerosol direct effects has better 45 performance than the simulations with no aerosol feedbacks or including both direct and indirect 46 effects. The normalized mean biases are significantly reduced by 10-20% for PM10 when 47 including aerosol direct effects. The analysis for the dust case confirms that models perform 48 better when including aerosol direct effects, but worse when including both aerosol direct and 49 indirect effects, which suggests that the representation of aerosol indirect effects needs to be 50 improved in the model. 51 52 M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT Key words: aerosol direct effects, feedback, PM10, fire and dust 1 2 Highlights 3 4
Meteorological and Air Quality Models for Urban Areas, 2009
Many urban surface energy balance models now exist. These vary in complexity from simple schemes ... more Many urban surface energy balance models now exist. These vary in complexity from simple schemes that represent the city as a concrete slab, to those which incorporate detailed representations of momentum and energy fluxes distributed within the atmospheric boundary layer. While many of these schemes have been evaluated against observations, with some models even compared with the same data sets, such evaluations have not been undertaken in a controlled manner to enable direct comparison. For other types of climate model, for instance the Project for Intercomparison of Land-Surface Parameterization Schemes (PILPS) experiments , such controlled comparisons have been shown to provide important insights into both the mechanics of the models and the physics of the real world. This paper describes the progress that has been made to date on a systematic and controlled comparison of urban surface schemes. The models to be considered, and their key attributes, are described, along with the methodology to be used for the evaluation.
Ulaanbaatar, the capital city of Mongolia is subject to high air particulate matter pollution epi... more Ulaanbaatar, the capital city of Mongolia is subject to high air particulate matter pollution episodes during winter and during dust storm events in spring and autumn that have severe implications for the health of the exposed population. This paper presents the results of fine (PM2. 5) and coarse (PM10–2.5) particulate matter monitoring in Ulaanbaatar from 2004 to 2008 and receptor modelling to determine the sources contributing to particulate matter pollution. Ion Beam Analysis was used to determine elemental ...
The size distribution of aerosols containing metal was investigated in the Monchegorsk region. It... more The size distribution of aerosols containing metal was investigated in the Monchegorsk region. It was found that lead and arsenic occur predominantly in fine particles ( < 1 pm) and that copper and nickel occur both in fine (< 1 pm) and coarse particles. The mean ratios of total mass (all size ranges) Cu/Pb and Cu/As in the air were found to be 10 and 16, respectively. Comparing these ratios with the snowpack data of Jaffe et al. (1994) in the Monchegorsk region, we find an enhancement of Cu in the snowpack, relative to Pb and As. This is consistent with our observed size distributions and indicates that the Monchegorsk Pb and As emissions are transported longer distances than Cu and Ni prior to removal. Results show the importance of considering the size distribution of metal emissions in chemical transport and/or factor analysis type models.
Snowpack samples were collected at 20 sites on the Kola Peninsula, Russia, in April 1991. Samples... more Snowpack samples were collected at 20 sites on the Kola Peninsula, Russia, in April 1991. Samples were collected both in remote regions and in areas impacted by nearby emission sources, including the Severonikel Cu-Ni smelter in the city of Monchegorsk. In the background regions, total winter deposition for non-seasalt SO:-, NO;, Cu, and Ni were 120-300, 70-300, 6-14, and 0.3-M mg/m2, respectively, and the snowpack pH ranged from 4.4 to 4.9. In the region near the Severonikel Cu-Ni smelter, snowpack SO:-, Cu, and Ni concentrations were enhanced considerably.
Physics and Chemistry of the Earth, Part B: Hydrology, Oceans and Atmosphere, 2001
Radionuclides are released into the atmosphere in the form of gases or aerosols. The aerosols hav... more Radionuclides are released into the atmosphere in the form of gases or aerosols. The aerosols have different particle sizes (0.01-60 Ixm). This paper analyses parameterisations of the removal processes by dry and wet deposition of radionuclides to the ground, and recommends some parameterisations and their realisation for the DERMA model as an example. It is shown that the washout coefficient strongly depends on the particle size. This dependence, however, is not included in most atmospheric dispersion models. Therefore, a revised formulation of the wet deposition parameterisation for particles of different size is suggested. The effect of gravitational settling is included in the dry deposition parameterisation by a combination of Stokes' law with the Cunningham correction for small particles and an iterative procedure solving the differential equation for the terminal settling velocity for large particles. Comparisons of simulation results for the Algeciras accident, Spain, with measurement data from the European monitoring network are presented and discussed.
Regional air pollution models are usually off-line coupled with numerical weather prediction mode... more Regional air pollution models are usually off-line coupled with numerical weather prediction models. The present study, however, focuses on on-line coupled modelling, for which the air pollution model is an integral part of the meteorological model. To this purpose, simulations of the first European Tracer Experiment (ETEX), which supplies the best suited verification data for dispersion modelling of a passive tracer, have been performed using versions of the Danish Meteorological Institute High Resolution Limited-Area Model (DMI-HIRLAM). Simulation results have been compared with observed values as well as with results from other models.
The three-dimensional atmospheric dispersion model DERMA is of Lagrangian type making use of a hy... more The three-dimensional atmospheric dispersion model DERMA is of Lagrangian type making use of a hybrid stochastic particle-puff diffusion description. It is currently capable of describing plumes at downwind distances greater than about 20 km and up to the global scale. The model employs aerosolsize dependent dry and wet deposition parameterisations. DERMA is developed and used mainly for nuclear emergency preparedness purposes, and it has recently become integrated with the ARGOS nuclear decision-support system.
KEYWORDS diffusion battery, aerosol generators, size distribution, CPC, ADB As a result of fundam... more KEYWORDS diffusion battery, aerosol generators, size distribution, CPC, ADB As a result of fundamental researches of photo -induced nucleation, we have designed a set of photochemical -type of aerosol generators for testing the sensitivity and size resolution of different types of aerosols counters. The set covers particles size range from 2 to 1OO nm, and concentration rangeup to 107 particles/cc. It consists of three generators. The first two generators produce metal ,oxide (WO and MoO ) particx ~ x 7 3 les with number concentration (N a) in the range IO J -10" cm--, particles diameter (alp)-from 2 to 10 nm, standard geometric deviation (o s) is about I .4. The third one is photochemical generator, based on haloidaromatic compounds photolysis [1 ]. Na 105 + 107 cm -3, size range -from 2 to 100 nm in diameter, o -1.2 -1.6, depending on d .
Environmental Science and Pollution Research, 2013
There is extensive evidence of the negative impacts on health linked to the rise of the regional ... more There is extensive evidence of the negative impacts on health linked to the rise of the regional background of PM10 levels. These levels are often increased over urban areas becoming one of the main air pollution concerns. This is the case on the Bilbao metropolitan area, Spain. This study describes a data-driven model to diagnose PM10 levels in Bilbao at hourly intervals. The model is built with a training period of sevenyear historical data covering different urban environments (inland, city centre and coastal sites). The explanatory variables are quantitative -log [NO2], temperature, short-wave incoming radiation, wind speed and direction, specific humidity, hour and vehicle intensity -and qualitative -working days/weekends, season (winter/summer), the hour (from 00 to 23 UTC) and precipitation/no precipitation. Three different linear regression models are compared: simple linear regression (LIN); linear regression with interaction terms (INT) and linear regression with interaction terms following the Sawa's Bayesian Information Criteria (INT-BIC). Each type of model is calculated selecting two different periods: the training (it consists on 6 years) and the testing dataset (it consists on 1 year). The results of each type of model shows that the INT-BIC based model (R2 = 0.42) is the best. Results were R of 0.65, 0.63 and 0.60 for the city centre, inland and coastal sites, respectively, a level of confidence similar to the state-of-the art in the methodology. The error related calculated for longer time intervals (monthly or seasonal means) diminished significantly (R of 0.75-0.80 for monthly means and R of 0.80 to 0.98 at seasonally means) with respect to shorter periods
The main focus of this paper is the description of a methodology for probabilistic or long-term e... more The main focus of this paper is the description of a methodology for probabilistic or long-term evaluation of the atmospheric transport and deposition of harmful (for example radioactive) releases from risk sites based on a dispersion modelling approach. This work was realised as a part of the multidisciplinary 'Arctic Risk' study; the purpose of which was the development of a methodology for environmental risk and vulnerability assessments and the testing of this methodology through estimation of the nuclear risk to the population in the Northern European countries in case of a severe accident at a nuclear risk site. The following research tools were applied for probabilistic atmospheric studies:
Traditionally, transport and dispersion models are offline coupled to meteorological drivers, rec... more Traditionally, transport and dispersion models are offline coupled to meteorological drivers, receiving pre-processed output at regular coupling intervals. However, today meteorological models have reached urban and cloud resolving scales and online models integrating meteorological and dispersion models have been developed. In this study the online coupled model, Enviro-HIRLAM, which can also run in offline mode, was used to compare online and offline representations of meso-scale disturbances. The online model was evaluated using data from the first European Tracer Experiment (ETEX-1) and produced satisfactory results. Meso-scale influences during the simulation pertube the plume during long-range transport, leading to a double peak structure at a specific measurement station. The mesoscale influence was investigated by varying the offline coupling interval which was shown to be important in constraining the influence of meso-scale disturbances on plume structure in coarse resolution.
The increased resolution of numerical weather prediction models allows nowadays addressing more r... more The increased resolution of numerical weather prediction models allows nowadays addressing more realistically urban meteorology and air pollution processes. This has triggered new interest in modelling and describing experimentally the specific features and processes of urban areas. Recent developments and results performed within the EU-funded project FUMAPEX on integrated systems for forecasting urban meteorology and air pollution are reported here. Sensitivity studies with respect to optimum resolution, parametrisation of urban roughness and surface exchange fluxes and the role of urban soil layers are carried out with advanced meso-or sub-meso meteorological models. They show that sensible improvements can be achieved by higher model resolution that is accompanied with better description of urban surface features. Recommendations, especially with respect to advanced urban air quality forecasting and information systems, are given together with an assessment of the needed further research and data.
The quality of the urban air pollution forecast critically depends on the mapping of emissions, t... more The quality of the urban air pollution forecast critically depends on the mapping of emissions, the urban air pollution models, and the meteorological data. The quality of the meteorological data should be largely enhanced by using downscaled data from advanced numerical weather prediction models. These different topics, as well as the application of population exposure models, have traditionally been treated in distinct scientific communities whose expertise needs to be combined to enhance the possibilities of forecasting air pollution episodes in European cities. For this purpose the EU project "Integrated Systems for Forecasting Urban Meteorology, Air Pollution and Population Exposure" (FUMAPEX) (http://fumapex.dmi.dk), involving 22 organizations from 10 European countries, was initiated. The main objectives of the project are the improvement of meteorological forecasts for urban areas, the connection of numerical weather prediction models to urban air pollution and population exposure models, the building of improved Urban Air Quality Information and Forecasting Systems, and their application in cities in various European climates. This paper overviews the project items and first two-years results, it is an introduction to the whole ACP issue.
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Papers by A. Baklanov