Elsevier

Atmospheric Environment

Volume 84, February 2014, Pages 178-188
Atmospheric Environment

Assessment of the AMS-MINNI system capabilities to simulate air quality over Italy for the calendar year 2005

https://doi.org/10.1016/j.atmosenv.2013.11.006Get rights and content

Highlights

  • First yearly air quality study over whole Italy using modeling and measurements.

  • 3rd study verifying compliance of an air quality system with last AQ EU directive.

  • A multi-pollutant study based on an up-to-date model and coherent/consistent data.

Abstract

This paper presents a comprehensive evaluation of AMS-MINNI modelling system for the year 2005, over Italian peninsula and major islands Sicily and Sardinia, for gas-phase species ozone (O3) and nitrogen dioxide (NO2), and particulate matter with an aerodynamic diameter less than or equal to 10 μm (PM10), against surface measurements from the Italian air quality database. Statistical indicators currently used in air quality models performance assessment and recommended by European Union (EU) guidelines were calculated at rural, urban and suburban background air quality monitoring stations, on purpose of understanding the model behaviour in areas not directly affected by anthropogenic pollution sources. Results show that measured O3 concentrations are generally well reproduced by the model, with the best agreement between model and observations at rural stations. Simulated PM10 annual average concentrations are generally lower than those observed but simulated and observed variabilities are comparable at urban and suburban stations. As for NO2, the model underestimates concentrations at all stations but gives similar variability to the observed one. Overall, the values of the statistical indicators comply with the acceptance criteria requested by EU legislation and are similar with those published by previous studies for the three pollutants investigated in this study. Further work will be carried out to evaluate the impact of uncertainties in input data (meteorology, emissions and boundary conditions) and in description of gaseous and aerosol chemical and physical processes on the simulated concentrations.

Introduction

The air pollution standards (EC, 2008) for the ground-level ozone (O3), nitrogen dioxide (NO2) and particulate matter (PM10) are still exceeded in many regions of Europe in spite of steadily reductions of anthropogenic emissions over the last two decades (EEA, 2010). For O3, the effect of emissions reduction is probably masked by inter-annual meteorological variability or by the long-range transport of air pollutants in synergy with an increase of global background concentrations in Northern Hemisphere. In Italy, the pollution is characterized by high ozone concentrations during summer (Silibello et al., 1998, Vecchi and Valli, 1999, Nolle et al., 2002, Liu et al., 2007, de Meij et al., 2009, Schurmann et al., 2009, Gottardini et al., 2010), much higher than in the rest of Europe (EEA, 2010), very high concentrations of PM10 during winter in the Po Valley (Marcazzan et al., 2001, Vecchi et al., 2009, Stortini et al., 2009, Lonati et al., 2010) and random contributions of Saharan dust to PM10 during spring and summer over the whole country (Matassoni et al., 2009, Pederzoli et al., 2010). High PM10 concentrations were also recorded in other parts of the country such as the central-western city of Rome (Perrino et al., 2008) and southern regions (Sprovieri and Pirrone, 2008, Contini et al., 2010).

Over the years, studies using AQ models were performed over parts of Po Valley (Liu et al., 2007, Angelino et al., 2008, Carnevale et al., 2008, Andreani-Aksoyoglu et al., 2008, de Meij et al., 2009, Lonati et al., 2010, Pernigotti et al., 2012) and in cities such as Milan (Silibello et al., 1998, Silibello et al., 2008, Vautard et al., 2007, Thunis et al., 2007), Venice (Benassi et al., 2011), Rome (Gariazzo et al., 2007) and Cosenza (Schurmann et al., 2009). Most of the studies were carried out for short time periods, only three of them have analysed the model behaviour over a full year (Angelino et al., 2008, Carnevale et al., 2008, Lonati et al., 2010). Some studies were devoted only to O3 investigation (Silibello et al., 1998, Liu et al., 2007, Schurmann et al., 2009), while others have analysed only PM10 (Angelino et al., 2008, Andreani-Aksoyoglu et al., 2008, Carnevale et al., 2008, Silibello et al., 2008, Pernigotti et al., 2012). Results for both O3 and PM10 have been studied by Gariazzo et al., 2007, de Meij et al., 2009, Lonati et al., 2010, Benassi et al., 2011.

Over the whole Italy, including Sardinia and Sicily islands, the ozone concentrations fields were studied by Mircea et al. (2008) but only for few summer and winter days. Their results show high ozone concentrations all over the country during summer and, in particular, in urban and industrialised area not yet investigated as shown in the above literature review. It is worth noting that no such study exists for PM10.

In this context, a multi-pollutant air quality investigation over the whole Italy for a long period of time in order to minimize the impact of episodic conditions is a mandatory step for air quality assessment and management at national level. This paper shows the results of such study regarding O3, PM10 and NO2, the last being an important precursor for both O3 and PM10. SO2 is not presented since both measured and simulated concentrations are well below the threshold value all over the country, while for other pollutants regulated by the Directive 2008/50/EC (EC, 2008) such as PM2.5, etc, only few measurements were available. The study was carried out with the Atmospheric Modelling System of MINNI project (AMS-MINNI; Zanini et al., 2005, Mircea et al., 2010a, Mircea et al., 2010b). MINNI (Italian Integrated Assessment Modelling System for supporting the International Negotiation Process on Air Pollution and assessing Air Quality Policies at national/local level) is funded by the Italian Ministry for Environment and Territory and Sea (MATTM) and is composed of AMS-MINNI and the Integrated Assessment Model GAINS-Italy (Greenhouse Gas and Air Pollution Interactions and Synergies Model over Italy) that interact with each other. AMS-MINNI uses alternative and/or future emission scenarios produced by GAINS-Italy to predict air pollution while GAINS-Italy relies on AMS-MINNI predictions for fast-response evaluation of scenarios impact on concentration levels (see for instance D'Elia et al., 2009).

The results presented hereafter evaluate the capacity of AMS-MINNI to simulate the concentrations of air pollutants and assess the air quality situation for the year 2005. The air quality studies published until now have investigated previous years, up to 2004, except Pernigotti et al. (2012) that have explored January 2005. In addition to that, the choice of the year was determined also by the following reasons: a) it is a reference year for the directive 2008/50/EC; b) it is the latest year for which harmonized emission inventories are available in European countries; c) European research projects like MEGAPOLI (Baklanov et al., 2010) and TRANSPHORM (http://www.transphorm.eu/) have also used this year for relevant air quality studies within FP7 framework and d) it is the latest year for which the national emission inventory is scaled down at NUTS3 level by applying a top-down approach (this procedure is applied every 5 years). AMS-MINNI and the methodology used for evaluating model performances (modelling set-up, monitoring data and statistical indicators) are described in Section 2. Then, the performances of the multi-pollutant modelling approach and of the current standard set-up are shown and discussed in relation to the type of the sites (e.g. rural, suburban, urban), pollution conditions, time of the year and current European legislation. This extensive evaluation of model results against measurements is shown in Section 3. Conclusions and suggestions for further work are presented in Section 4.

Section snippets

Description of AMS-MINNI and of modelling set-up

The main components of AMS-MINNI are the meteorological model RAMS (Regional Atmospheric Modelling System, Version 6.0, Cotton et al., 2003), the emission processor EMMA (EMission MAnager, ARIA/ARIANET, 2008) and the FARM (Flexible Air Quality Regional Model Silibello et al., 1998, Silibello et al., 2008, Gariazzo et al., 2007, Kukkonen et al., 2012).

RAMS is a three-dimensional non-hydrostatic meteorological model, based on fundamental equations of fluid dynamics discretized on a terrain

Results and discussions

The modelling system was run with its standard configuration and codes. The proportion of available data requested at stations was 90% over summer (April to September) and 75% over winter (January to March, October to December) seasons separately, for O3 and NO2 while 90% of data distributed over the whole year was requested for PM10.

This section shows the annual mean distributions of O3, NO2 and PM10 surface concentrations over Italy aiming to determine specific pollution patterns and their

Concluding remarks

This study, based on model simulations and measurements, provides a first assessment of air pollution over Italy, for a whole year, and an operational evaluation of the modelling system AMS-MINNI which is the tool used by MATTM to assess compliance with the air quality limits and target values set out in the EU legislation. The work was carried out for the calendar year 2005 using up-to-date meteorological data, emission inventories and the advanced atmospheric modelling system AMS-MINNI based

Acknowledgements

This work is part of the MINNI (Integrated National Model in support to the International Negotiation on Air Pollution) project, funded by the Italian Ministry for Environment and Territory and Sea, coordinated by ENEA.

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