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Impact of Grid Resolution on Aerosol Predictions: A Case Study over Italy

Category: Air Pollution Modeling

Volume: 16 | Issue: 5 | Pages: 1253-1267
DOI: 10.4209/aaqr.2015.02.0058
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Mihaela Mircea 1, Georgiana Grigoras3, Massimo D’Isidoro1, Gaia Righini1, Mario Adani1, Gino Briganti1, Luisella Ciancarella1, Andrea Cappelletti1, Giuseppe Calori2, Irene Cionni1, Giuseppe Cremona1, Sandro Finardi2, Bo R. Larsen4, Giandomenico Pace6, Cinzia Perrino5, Antonio Piersanti1, Camillo Silibello2, Lina Vitali1, Gabriele Zanini1

  • 1 ENEA - National Agency for New Technologies, Energy and Sustainable Economic Development, via Martiri di Monte Sole 4, 40129 Bologna, Italy
  • 2 ARIANET Srl, via Gilino 9, 20128, Milan, Italy
  • 3 National Institute for Research and Development in Environmental Protection, 294 Splaiul Independentei, 6th District, 060031, Bucharest, Romania
  • 4 European Commission, Joint Research Centre, Institute for Health and Consumer Protection, Via Enrico Fermi 2749, Ispra (VA) 21027, Italy
  • 5 C.N.R. Institute of Atmospheric Pollution, Via Salaria Km. 29,300 – 00015 Monterotondo St., Rome, Italy
  • 6 Laboratory for Earth Observations and Analyses, ENEA, Via Anguillarese 301, 00123 Roma, Italy

Highlights

Grid impact on inorganic and organic aerosols, of primary and secondary origin.

Grid impact long-term study on aerosols in a complex orographic and climatic area.

Grid influence evaluation in different seasons and daily and nightly during summer.


Abstract

This study investigates the effect of grid resolution on the particulate matter (PM10, PM2.5) mass concentrations and its chemical composition simulated with the AMS-MINNI modelling system. The air pollution was simulated over Italy with grid resolutions of 20 and 4 km, for a whole year. The gridded emissions were produced performing speciation and space-time disaggregation of aggregated inventory data, using both land use information and anthropogenic activity-based profiles. Often, the fine grid simulations, based on high resolution gridded emissions, improved the agreement between model and measurements. In particular, the use of a fine grid improved predictions of primary species such as elemental carbon (EC), PM10 and PM2.5 mainly at urban stations. An improvement of predicted PM components and mass concentration at high altitudes sites was also observed, especially during winter. However, a general overestimation of nitrate (NO3) and of secondary inorganic species, more evident at night than during the day, was increased by employing a finer grid. Organic carbon (OC) was more affected by the grid resolution than the other species. At urban and kerbside stations, the use of a finer grid resulted in an overestimation of primary organic carbon aerosol (POC) but had a negligible effect on secondary organic carbon aerosol (SOC). The overestimation of carbonaceous aerosol (defined as the sum of EC, POC and SOC), at an urban station, opposite to general underestimation of this component by air quality (AQ) models, indicates that the anthropogenic emissions can contribute as much as organic model formulation at the success of simulation in reproducing experimental data.

The modelling results obtained under stable meteorological conditions characterised by weak winds, which are often encountered in the Po Valley, did not improve substantially by the increase of the modelling system resolution.

Keywords

Horizontal grid resolution Aerosol chemical composition PM10 PM2.5 Air quality modelling


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