A model for the estimation of standard deviation of air pollution concentration in different stability conditions

We propose to estimate the standard deviations of the air pollution concentration in the horizontal and vertical direction, σy and σz, based on Pasquill’s well-known equation, in terms of the wind variance and the Lagrangian integral time scales, on the basis of an atmospheric turbulence spectra model. The main advantage of the spectral model is its treatment of turbulent kinetic energy spectra as the sum of buoyancy and a shear produced part, modelling each one separately. The formulation represents both shear and buoyant turbulent mechanisms characterizing the various regimes of the Planetary Boundary Layer, and gives continuous values at any elevation and all stability conditions from unstable to stable. As a consequence, both the wind variance and the Lagrangian integral time scales in the dispersion parameters are more general than those found in literature, because they are not derived from diffusion experiments as most parameterizations. Furthermore, they provide a formulation continuous for the whole boundary layer resulting more physically consistent. The σy, σz parameters, included in a Gaussian model have been tested and compared with a dispersion scheme reported in the literature, using experimental data in different emission conditions (low and tall stacks) and in several meteorological conditions ranging from stable to convective. Results show that the dispersion model with the sigmas parameterisation included, produces a good fitting of the measured ground-level concentration data in all the experimental conditions considered, performing slightly better than other state-of-art models

Effects of vertical shear in modelling horizontal oceanic dispersion

Abstract. The effect of vertical shear on the horizontal dispersion properties of passive tracer particles on the continental shelf of the South Mediterranean is investigated by means of observation and model data. In situ current measurements reveal that vertical gradients of horizontal velocities in the upper mixing layer decorrelate quite fast ( ∼  1 day), whereas an eddy-permitting ocean model, such as the Mediterranean Forecasting System, tends to overestimate such decorrelation time because of finite resolution effects. Horizontal dispersion, simulated by the Mediterranean sea Forecasting System, is mostly affected by: (1) unresolved scale motions, and mesoscale motions that are largely smoothed out at scales close to the grid spacing; (2) poorly resolved time variability in the profiles of the horizontal velocities in the upper layer. For the case study we have analysed, we show that a suitable use of deterministic kinematic parametrizations is helpful to implement realistic statistical features of tracer dispersion in two and three dimensions. The approach here suggested provides a functional tool to control the horizontal spreading of small organisms or substance concentrations, and is thus relevant for marine biology, pollutant dispersion as well as oil spill applications

A GIS BASED AIR QUALITY SYSTEM FOR THE APULIA REGION, SOUTHERN ITALY

Apulia region in the Southern Italy is frequently characterised by high photochemical pollution levels in the warm period and by high levels of PM10 and NO2 in the winter season. Emissions in the area derive essentially from urban, shipping and industrial activities. The main industrial activities are related to the iron and steel industry (one of the largest in Europe) on the western coast and to two coal power plants on the eastern coastline. A GIS based air quality system has been developed to support local authorities in air quality management for the region. The proposed modeling system is based on RAMS (Pielke et al., 1992) and CALMET (Scire et al., 2000) meteorological models and on CALPUFF (Scire et al., 2000)/ CALGRID (Yamartino et al., 1989) dispersion models. Diffuse emissions for the domain were obtained from the national CORINAIR data base (www.sinanet.apat.gov.it) and were preprocessed by a new-developed tool GEM-PP (Gis EMission Pre-Processor) based on open source GIS. Point sources emissions are obtained by local inventory. Meteorological and dispersion simulations were performed for the year 2005. Predictions have been compared with concentration data from the air quality monitoring network. Results evidence a good correlation between predictions and measurements for O3, NOx, SO2 with most of data in factor of two of the measurements for rural stations and a tendency to underestimate measured data in urban stations. Overall the model tends to underestimate CO measurements. The uncertainty of the predictions are analysed and discussed in terms of the emission calculations, dispersion modelling and monitoring site

Effects of vertical shear in modelling horizontal oceanic dispersion

The effect of vertical shear on the horizontal dispersion properties of passive tracer particles on the continental shelf of the South Mediterranean is investigated by means of observation and model data. In situ current measurements reveal that vertical gradients of horizontal velocities in the upper mixing layer decorrelate quite fast ( ∼  1 day), whereas an eddy-permitting ocean model, such as the Mediterranean Forecasting System, tends to overestimate such decorrelation time because of finite resolution effects. Horizontal dispersion, simulated by the Mediterranean sea Forecasting System, is mostly affected by: (1) unresolved scale motions, and mesoscale motions that are largely smoothed out at scales close to the grid spacing; (2) poorly resolved time variability in the profiles of the horizontal velocities in the upper layer. For the case study we have analysed, we show that a suitable use of deterministic kinematic parametrizations is helpful to implement realistic statistical features of tracer dispersion in two and three dimensions. The approach here suggested provides a functional tool to control the horizontal spreading of small organisms or substance concentrations, and is thus relevant for marine biology, pollutant dispersion as well as oil spill applications

Evaluation of industrial sources' contribution to PM10 concentrations over a coastal area

The analysis of air quality data in a monitoring site in the southern part of the Apulia region (south-eastern Italy) has shown that it exceeds the daily mean value of particulate matter with an aerodynamic diameter less than 10 μm (PM10) established by Italian regulations in force. In the neighbourhood of the site relevant power plants are present. The aim of this study is to evaluate the contribution of these industrial sources using the RAMS [1]-CALMET [2]- CALPUFF [3] modelling system. Results show that the contribution of industrial sources is significant to the total pollution, but such a contribution explains only a small percentage of the PM10 measured in the site. The fallout of primary particulate matter has turned out very low, while the contribution of the secondary one, related mostly to SOx and NOx emission, has been higher. Meteorological and dispersion simulation indicate that the high values registered in the site can be attributed to a local source present in the little town where the station is placed and are representative of a very small area

Effects of vertical shear in modelling horizontal oceanic dispersion

The effect of vertical shear on the horizontal dispersion properties of passive tracer particles on the continental shelf of the South Mediterranean is investigated by means of observation and model data. In situ current measurements reveal that vertical gradients of horizontal velocities in the upper mixing layer decorrelate quite fast ( ∼  1 day), whereas an eddy-permitting ocean model, such as the Mediterranean Forecasting System, tends to overestimate such decorrelation time because of finite resolution effects. Horizontal dispersion, simulated by the Mediterranean sea Forecasting System, is mostly affected by: (1) unresolved scale motions, and mesoscale motions that are largely smoothed out at scales close to the grid spacing; (2) poorly resolved time variability in the profiles of the horizontal velocities in the upper layer. For the case study we have analysed, we show that a suitable use of deterministic kinematic parametrizations is helpful to implement realistic statistical features of tracer dispersion in two and three dimensions. The approach here suggested provides a functional tool to control the horizontal spreading of small organisms or substance concentrations, and is thus relevant for marine biology, pollutant dispersion as well as oil spill applications

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G-AQFS (Grid Air Quality Forecast System): An experimental system based on GRID computing technologies to forecast atmospheric dispersion of pollutants

Aim of this work is the implementation of an integrated system for modeling air pollutants dispersion using GRID computing technologies. The system includes two meteorological models, emission pre-processors and two dispersion models for inert and photochemical pollutants. Both meteorological and dispersion models use models which run on the European scale for the initial and boundary conditions. As a test, the modeling system has been applied to the Salento Peninsula, located in the south-east corner of Italy, in the Mediterranean central area with complex meteorological conditions

G-AQFS: Grid computing exploitation for the management of air quality in presence of complex meteorological circulations

Leveraging grid computing technology, i.e. the visualization of distributed computing and data resources such as processing, network bandwidth and storage capacity to create a single system image, we present a Grid Air Quality Forecast System (G-AQFS). The modeling system consists of meteorological and dispersion models coupled in cascade. The computational workflow of the modeling system is defined by means of DAGs (direct acyclic graph). A simple system is presented to manage and schedule the computational grid resources. As case study the system has been applied over Salento area, in the Apulia region (South-eastern Italy), to simulate ground level ozone concentration. Model predictions have been compared with field measurements, with reasonable results