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Università Politecnica delle Marche (2019)

Air Pollution from Natural and Anthropogenic Sources over Mediterranean Region : Assessment of an Online Coupled Meteorological and Air Quality Model

MORICHETTI, MAURO

Titre : Air Pollution from Natural and Anthropogenic Sources over Mediterranean Region : Assessment of an Online Coupled Meteorological and Air Quality Model

Auteur : MORICHETTI, MAURO

Université de soutenance : Università Politecnica delle Marche

Grade : Dottorato in Ingegneria Industriale 2019

Résumé
A study to better understand and quantify the source of air pollution in Italy and the surrounding Mediterranean region is proposed. Suspected sources of pollutants include human activities, natural hydrocarbons from forests (isoprene and terpenes) and episodes of wind-blown mineral dust from the Sahara Desert. A deep understanding of these sources is fundamental to developing science-based mitigation actions. The study addresses specifically the natural hydrocarbons and dust, using a state-of-the-art chemistry transport model (Weather Research and Forecasting with Chemistry). The WRF-Chem system is an “online” regional scale prediction model designed to simulate many detailed meteorological, gas and aerosol chemical processes, with full coupling between the different components and phases. This study documents two different applications, and their evaluation, that have been made using WRF-Chem model in order to improve its representation of gas and aerosol chemical processes. The first application includes the description, examination and test of a set of updates made to the MEGAN version 2.04 (Model of Emission Gas and Aerosols from Nature) model, one of the BVOC (biogenic volatile organic compound) emission model includes in WRF-Chem, by two different test cases (i.e. the first at European level, and the second, at United States level). The main objective of the second WRF- Chem application, involves the assessment of Sharan dust outbreaks to the southern Europe and how they compare to anthropogenic emissions over a whole year (2017). The MEGAN sensitivity study, at European level, includes four simulations. The first one is (1) the control one : the MEGAN database has been used without any change (Megan_V2.04) ; on the (2) second one all the activity factors (γi) have been modified following the MEGAN version 2.10 (Megan_Gamma). The (3) third simulation adds the PFTs (Plant Functional Type) emission factors changes to the activity factors (Megan_GammaPFT) ; finally, the (4) last one calculates more the isoprene emission factor within the MEGAN emission algorithm, instead of reading it directly from the input database (Megan_GammaPFTISO). The simulations listed above, are applied to simulate an intense ozone event that took place over central Italy in August 13th, 2015. Results for isoprene and α-pinene emissions demonstrate the updating the MEGAN code the emissions increase considerably (i.e. Zagreb has an increase about 100 mol/km2hr and Kiev about 50 mol/km2 hr). The comparison with the AIRBASE (European Environment Agency air quality network) showed that only the temporal and spatial distribution of the O3 are well represented ; the control simulation demonstrated the ozone better results, since the updates simulations increase the ozone concentration of nearly from 20 to 40 ppb. The other trace gases considered (NO2 and CO) model results are very underestimate, respectively by a factor of 2 and 10 regardless of simulations considered, since the MEGAN updates does not affect that compounds

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Page publiée le 24 avril 2021