Sandro Finardi

Potential and Shortcomings of Numerical Weather Prediction Models in Providing Meteorological Data for Urban Air Pollution Forecasting

The last decade progress in numericalweather prediction (NWP) modelling and studies of urbanatmospheric processes for providing meteorological data forurban air pollution forecasting is analysed on examples ofseveral European meteorological centres. Modern nested NWP models are utilising land-use databasesdown to 1 km resolution or finer, and are approaching thenecessary horizontal and vertical resolution suitable forcity scale. The recent scientific developments in the fieldof urban atmospheric physics and the growing availabilityof high-resolution urban surface characteristics datapromise further improvements of the capability of NWPmodels for this aim. A strategy to improve NWP data forthe urban air pollution forecasting is suggested.

TRANSALP 1989 experimental campaign - I. Simulation of 3D flow with diagnostic wind field models

Abstract The first TRANSALP meteorological and tracer campaign was carried out in October 1989 in the Ticino river valley, southern Switzerland, aiming to study air masses and pollutant transport through the Alps. The experiment was executed in a very complex terrain area, during typical valley breeze condition, which caused a plume bifurcation along two valleys. Meteorological instrumentation included three Doppler SODARs and several ground stations measuring wind speed and direction. Two diagnostic wind field models, CONDOR and MINERVE, were applied to TRANSALP 89, to investigate their ability to reproduce the main characteristics of the advection field driving the tracer dispersion, and to assess their sensitivity to the number and quality of input data. Although the two models differ in some features, especially in the numerical scheme to solve the continuity equation, they give comparable results. The models were first run with only one surface observation and one vertical profile taken near the release point as input wind data to represent the flow. Then several runs, combined with tracer dispersion simulations by 3D particle models, were executed in order to investigate the models sensitivity with respect to the number and location of input wind data. The most significant results of the flow modelling are discussed, and the computed wind fields chosen to drive the dispersion simulation, described in the companion paper (Anfossi et al., Atmospheric Environment 32, 1157–1166), are shown.

Discrepancies Between Top-Down and Bottom-Up Emission Inventories of Megacities: The Causes and Relevance for Modeling Concentrations and Exposure

A state-of-the-art regional European emission data base is combined and cross-checked with bottom-up emission inventories of Paris, London, Rhine-Ruhr area (Germany) and the Po-valley (Italy). It is shown that the allocation of the emission in the regional top-down inventory can deviate substantially from the megacity bottom-up inventories. For example, the PM10 and NOx in local inventories are respectively 26% and 62% (London), 33% and 95% (Paris), 55% and 108% (Rhine-Ruhr) and 110% and 107% (Po valley) of the emission allocated to the same area in the regional inventory. The match for the Po Valley is reasonable but if we zoom in on a city level (Milan) similar problems as seen in Paris and London surface. We conclude that the European scale inventory is consistent with official reported national emissions but local-national-regional scale inventories are not consistent. Since the discrepancies are large, predicted concentrations and population exposure estimates may be significantly different. Our work shows the importance of regionalization of emissions for model input and argues that consistency between emission inventories at different scales deserves more attention.

Modeling Air Quality over Italy with MINNI Atmospheric Modeling System: From Regional to Local Scale

This study shows part of the results obtained during the operational evaluation of MINNI atmospheric modeling system over Italy. MINNI is the Italian Integrated Assessment Modelling System for supporting the International Negotiation Process on Air Pollution and assessing Air Quality Policies at national/local level sponsored by the Italian Ministry of the Environment. The evaluation was carried out for both meteorology and air quality for the years 1999 and 2005. Changes of meteorological variables and of ozone concentrations in relation to the change of horizontal grid resolution were also investigated. The results show the capability of the modelling system to reconstruct the meteorological and ozone fields over Italy.

Composition and emission of VOC from biogas produced by illegally managed waste landfills in Giugliano (Campania, Italy) and potential impact on the local population

The composition in Volatile Organic Compounds (VOC) of the biogas produced by seven landfills of Giugliano (Naples, Campania, Italy) was determined and VOC emission rates assessed to verify if these compounds represent a potential threat to the population living nearby. VOC composition in the biogas could not be predicted, as heterogeneous waste was dumped from the late 1980s to the early 2000s and then underwent biological degradation. No data are available on the amount and composition of VOC in the biogas before the landfills closure as no operational biogas collection system was present. In this study, VOC composition was determined by gas chromatography-mass spectrometry (GC-MS), after collecting samples from collection pipes and from soil fractures in cover soil or capping. Individual VOC were quantified and data compared with those collected at two landfills in Latium, when they were still in operation. Relevant differences were observed, mainly due to waste aging, but no specific VOC revealing toxic waste dumping was found, although the concurrent presence of certain compounds suggested that dumping of industrial wastes might have occurred. The average VOC emission was assessed and a dispersion model was run to find out if the emitted plume could affect the health of population. The results suggested that fugitive emissions did not represent a serious danger, since the concentrations simulated at the neighboring cities were below the threshold limits for acute and chronic diseases. However, VOC plume could cause annoyance at night when the steady state conditions of the atmosphere enhance pollutants accumulation in the lower layers. In addition, some of the emitted VOC, such as alkylbenzenes and monoterpenes, can contribute to tropospheric ozone formation.

Study of the Impact of Low vs. High Resolution Meteorology on Air Quality Simulations Using the MINNI Model Over Italy

Modelling air quality requires the description of a large number of processes interacting each other. In order to properly model concentrations of atmospheric pollutants it is crucial to have a realistic reproduction of meteorological parameters, which can be critical in areas presenting a complex orography like the Italian peninsula. This work shows an analysis of the results obtained with the national model MINNI at two different horizontal resolutions (20 and 4 km), for a whole year over Italy. Comparisons between modelled and observed temperature and pollutants concentrations are carried out. The prediction of temperature is improved with the increase of model spatial resolution, as it is for pollutants like NO2 and CO, while the improvement is not always evident for O3 concentrations. Results are discussed providing an interpretation of the observed features.

Simulations of the dispersion from a waste incinerator in the Turin area in three different meteorological scenarios

A numerical modelling study for the assessment of the air quality impact of a waste incinerator to be built in the city of Turin is presented, aimed at evaluating the ground level concentration distribution during adverse dispersion conditions, causing severe pollution episodes. The pollutant impact of the incinerator is evaluated with the three-dimensional modelling system RMS. This class of models is essential to get reliable simulations in 3-D complex conditions. A comparison vs. observed wind data is presented and various parameters elaborated from the concentration values are discussed for three episodes, in critical meteorological conditions from the pollutant dispersion viewpoint.

Atmospheric Dynamics and Ozone Cycle during Sea Breeze in a Mediterranean Complex Urbanized Coastal Site

AbstractPersistent high pressure conditions over the Mediterranean Basin favor the occurrence of sea breezes that can lead to ozone transport through complex recirculation patterns. These features ...

PAHs Modelling over Urban Area of Rome: Integration of Models Results with Experimental Data

The identification and quantification of population exposure of children and elderly people to PAHs in urban areas are the major goals of the EXPAH LIFE+ Project (www.ispesl.it/expah). To reach these objectives an integrated approach, based on measurements and modeling techniques, has been set up to preliminarily reconstruct PAHs levels in the Rome metropolitan area. Field campaigns of particulate PAHs and PM2.5 have been performed in different sites and microenvironments from December 2011 to July 2012. These data were essential to evaluate and integrate results of the Flexible Air quality Regional Model (FARM) that has been run from June 2011 to May 2012. PAHs modeled concentrations are presented for the city of Rome as well as a comparison with observations. Capabilities and limits in modeling PAHs in urban areas are then discussed.

Limitations of Air Pollution Episodes Forecast due to Boundary-Layer Parameterisations Implemented in Mesoscale Meteorological Models

Dispersion models require information on the turbulence characteristics in the planetary boundary layer (PBL). This information is most often extracted from either meteorological measurements or from numerical (prognostic or diagnostic) models, and the requested turbulence parameters are then estimated using a PBL pre-processor. Traditionally, Monin-Obukhov (M-O) similarity theory is applied when estimating the surface turbulent fluxes and the various vertical profiles of averaged quantities in the surface layer of the PBL (Beljaars and Holtslag 1991; Hanna and Chang 1992; Zilitinkevich et al. 2002b). In this similarity approach several simplifying assumptions are made, among which the requirement of quasi-stationary and horizontally homogeneous flow, and constant (independent of height) turbulent fluxes are the most crucial (Arya 1988). In urban areas and in complex terrain these assumptions are obviously not fulfilled. The theory is particularly questionable in very stable conditions, i.e. under conditions typically prevailing during pollution episodes in winter. In very stable conditions turbulence tends to be sporadic, and wave-turbulence interaction becomes increasingly important as well as drainage effects due to even small terrain slopes (Hogstrom 1996). Moreover, observational data suggest that developed turbulence can exist in the stably stratified surface layer at much larger Richardson numbers than the