Annalisa Tanzarella

Differences between weekend and weekday ozone levels over rural and urban sites in Southern Italy.

Air quality data from a network of 11 monitoring stations in the Apulia region of southern Italy during the summer of 2005 reveal a high frequency of ozone law limit violations. Since ozone is a secondary pollutant, air quality control strategies aimed at reducing ozone concentration are not immediate. Herein, we analyse weekly changes in concentration levels of ozone (O3), nitrogen oxides (NOx), carbon monoxide (CO), and volatile organic compounds (VOCs), and evaluate how the differences in primary emissions cause changes in the production of ozone. The comparison between weekend and weekday levels of O3 and its precursors are direct evidence for the existence of the “ozone weekend effect.” This effect was observed at all stations with a considerable variation in the overall ozone magnitude, including both traffic stations and non-traffic stations. Data from VOC measurements at traffic stations primarily indicated elevated levels of benzene, toluene, and xylenes (BTX); all of these substances showed an overall decrease over the weekend. A single station indicated levels of non-methane hydrocarbon (NMHC) and PM10, both of which did not demonstrate any weekly cycle. Analysis of weekly and diurnal cycles of O3, NOx, CO, NMHC, and PM10 indicates that higher weekend ozone levels result from a reduction in the emission of nitrogen oxides on weekends in VOC-sensitive regimes. This indicates that a reduction in VOC and NOx levels would be more effective than NOx reduction alone. Our results underscore the need for improved and more efficient VOC measurements.

Modelling local winds over the Salento peninsula

A three-day mesoscale numerical simulation has been performed over the narrow Salento peninsula (south-eastern Italy) during summer conditions characterised by weak synoptic forcing. These atmospheric conditions favour the development of complex sea-breeze systems and convergence zones on the peninsula. The aim of this work is to investigate the ability of an atmospheric mesoscale model to reproduce the surface fields of meteorological variables in the presence of local-scale forcing and breeze circulations, which are fundamental in applications such as air pollution modelling and nowcasting. The modelled fields have been compared with available surface measurements and sodar data. Results indicate that the model can simulate the general mean wind field in a realistic way. The diurnal evolution of the wind is well reproduced and the maximum deviations mostly occur during the night, being associated with calm conditions. Statistical analysis indicates that the typical mean bias is found to be about 1 m s−1 for hourly averaged wind speed, less than 20° for wind direction and about 1°C for temperature. The root mean square error (rmse) varies from 1 to 3 m s−1 for wind speed, from 50° to 70° for wind direction, and is about 2.4°C for temperature. All the values of the numerical indexes are within ranges which are characteristic of those found for other state-of-the-art models applied to similar cases studies. Despite a good overall agreement between predictions and observations, some discrepancies were found in the individual profiles due both to the limited spatial representation of the local details and to the complex wind field which makes the space–time matching between the model and the observations quite critical. The structures of the thermal mixed layer and the breeze convergence zone are similar to numerical studies relative to more idealised conditions. Copyright

Application of a Lagrangian particle model to the source apportionment for primary macropollutants in Taranto area (South Italy)

A modelling system has been applied to estimate the annual contribution to the total concentrations of different pollutant sources in Taranto, one of the most industrialized areas in Italy. Industrial sources, traffic, domestic heating and harbour emissions have been taken into account. Modelling system includes 3-dimensional meteorological models SWIFT-SURFPRO with the Lagrangian particle dispersion model SPRAY. The air emissions inventory was partially established using measured data, local activity indicators and emission factors. The meteorology was reconstructed by the SWIFT model from the products supplied, for the year 2007,by the national MINNI project. The annual simulation led to the identification of the main emitting sources for primary pollutants such as NOx, SO 2 , PM10, PM2.5 and C 6 H 6 at receptor sites. In addition, a more refined source apportionment was achieved for industrial primary PM10, providing a useful preliminary identification of the main industrial sources emitting dangerous micropollutants, such as POPs and heavy metals.

A GIS based air quality system for the Apulia region, southern Italy

A GIS based air quality modelling system has been developed in Apulia region in the Southern – Italy, to support local authorities in air quality management. 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, NO2, SO2, with a light 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 sites.

Application of a photochemical model for the assessment of regional air quality in Southern Italy: procedures and results

A modelling system based on FARM chemical transport model is applied to assess the air quality (AQ) over the Apulia region (Southern Italy) for 2013. The most relevant pollutant sources in the region are a steel plant, the largest in Europe (in the Taranto area), a coal fired power plant, the second most powerful in Italy (in the Brindisi area) and biomass burning for residential heating. Simulation results indicate exceedances for PM10 daily limit value and benzo(a)pyrene (B(a)P) annual limit values occurring in some areas. The evaluation of the model performance has been conducted by using the software DELTA Tool, developed within FAIRMODE to support the application of the EU Air Quality Directive. Results show good performance of the model, with a tendency to underestimate PM10 and O3 levels. These results suggest the use of this modelling strategy for further source apportionment studies, in order to identify the sources that mainly affect air quality and to implement proper emission control strategies.

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.