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  • 1. INTRODUCTION

    Projecting air quality for future decades is a chal-lenging subject, due to its complex and multifacetednature. Many factors influence air quality, and very

    often interference and masking effects make the pro-cesses of understanding the contribution of each fac-tor separately quite difficult. Firstly, changes in emis-sions can lead to different amounts of primarypollutants present in the air, and this can further alter

    Inter-Research 2011 www.int-res.com*Email: huszarpet@gmail.com

    Effects of climate change on ozone and particulatematter over Central and Eastern Europe

    P. Huszar1,*, K. Juda-Rezler2, T. Halenka1, H. Chervenkov3, D. Syrakov4, B. C. Krger5, P. Zanis6, D. Melas7, E. Katragkou7, M. Reizer2, W. Trapp8, M. Belda1

    1Department of Meteorology and Environment Protection, Charles University, 180 00 Prague, Czech Republic2Faculty of Environmental Engineering, Warsaw University of Technology, 00-653 Warsaw, Poland

    3National Institute of Meteorology and Hydrology branch Plovdiv, 4000 Plovdiv, Bulgaria4Department of Air and Water Pollution, National Institute of Meteorology and Hydrology, 1784 Sofia, Bulgaria

    5Institute of Meteorology, University of Natural Resources and Applied Life Sciences, 1190 Vienna, Austria6Department of Meteorology and Climatology, Aristotle University of Thessaloniki, 54 124 Thessaloniki, Greece

    7Laboratory of Atmospheric Physics, Aristotle University of Thessaloniki, 54 124 Thessaloniki, Greece8Air Protection Unit of Ekometria, 80-299 Gdansk, Poland

    ABSTRACT: We investigated the changes in exceedances of key atmospheric pollutants due to cli-mate change in central and southeastern Europe. The RegCM3/CAMx and ALADIN-CLIMATE/CMAQ regional climate-chemistry modelling systems were used for high-resolutionsimulations (10 km). The simulations performed cover 3 decadal time slices (19912000, 20412050,20912100). The future simulations were driven under the A1B IPCC scenario. Our model simula-tions yielded changes in ozone, particulate matter with a diameter

  • Clim Res 50: 5168, 2011

    the production/destruction of secondary pollutants.Secondly, air quality can be influenced by the state ofthe atmosphere, i.e. by the meteorological/climaticconditions. This influence can be direct, meaningthat the change in the magnitude of meteorologicalparameters (e.g. temperature, radiation, precipita-tion, mixing height) directly affects chemical produc-tion and loss processes as well as physical removalprocesses. Dawson et al. (2007) and Hedegaard et al.(2008) found that temperature has one of the largesteffects among the meteorological parameters. Krgeret al. (2008) also reported that increases in tempera-ture and radiation were the most important factorsfor the projected ozone increase in the 21st century.Change in circulation patterns at global and synopticscales as a result of climate change is another factorthat can affect pollution levels. For example, changesin Brewer-Dobson circulation in a future climate mayalso affect the stratospheretroposphere exchange,thereby also affecting the chemical composition ofthe troposphere (Collins et al. 2003, Stevenson etal. 2006). However, meteorology can also influenceatmospheric chemical composition indirectly throughbiogenic emissions of hydrocarbons which also havea strong impact on photochemical processes in thetroposphere. Concerning the indirect influence, Me -leux et al. (2007) studied summer European ozoneformation and found that increases in biogenic emis-sions due to temperature rise contributed to more fre-quent elevated ozone occurrence. Fiore et al. (2005)also emphasised the role of temperature change inozone formation through the modulation of biogenichydrocarbon emissions.

    It is now well established that significant environ-mental changes are expected in the future (IPCC2007). These changes will bring modified meteoro-logical conditions compared to the present. As notedabove, acting in a modified driving environment,tropo spheric chemistry processes are expected tochange as well. Therefore, a shift in the pollutantconcen tration distribution can be expected.

    Quantifying the effect of a changing climate on airquality and chemistry requires the use of climatechemistry models or chemistry transport models(CTMs) coupled to climate models. Numerous stud-ies have dealt with future air quality projections ona global scale using coupled climatechemistry models. Most of them focused on ozone on a globalscale (Hauglustaine et al. 2005, Stevenson et al. 2006,Racherla & Adams, 2006, 2008), while Hedegaard etal. (2008) also provided results for sulphur and nitro-gen dioxide (SO2 and NOx). Other studies have pro-vided information on regional- and local-scale air

    quality changes (Szopa et al. 2006, Meleux et al.2007, Nolte et al. 2008, Andersson & Engardt 2010).These focused on the average species concentrationchange, but only few results were given regardingthe impact on the occurrence of extreme air pollutionevents. A recent report issued by the U.S. Environ-mental Protection Agency (USEPA) assessing theregional impact of climate change on U.S. air qualityindicated that the number of high ozone situationswill increase in the future, potentially causing airquality alerts earlier in spring and later in the autumn(USEPA 2009). The increased frequency of elevatedozone levels due to higher temperatures in the futureclimate has been shown by many others as well (Bellet al. 2007, Mahmud et al. 2008, Zlatev 2009).

    In this study, we dealt with the assessment of cli-mate change impacts on air quality in central andsoutheastern Europe. We focused mostly on theextremes regarding air pollution on a regional scale.Besides ozone, the focus was also on particulate mat-ter with a diameter under 10 m (PM10) and SO2 asa precursor for aerosol formation. Setting up high-resolution domains on targeted areas over centraland southeastern Europe and running CTMs offline coupled to regional climate models for present con -ditions and selected future decades, we assessedthe response of air pollution to climate change. Weevaluated this response by means of exceedancesof pollutant thresholds in the present and future climate conditions in the above-mentioned regions.The work is based on the modelling concept de -scribed by Juda-Rezler et al. (in press).

    2. METHODOLOGY

    The basic idea of our approach lies in an appro -priate application of chemistry transport models onregional scales driven by regional climate modelsfor selected present and future decades. A detaileddescription of the theoretical base and modellingtools applied is given by Juda-Rezler et al. (in press).

    2.1. Overview of the concept and the experimentaldesign

    The regional climate models involved in the studywere RegCM3 (Pal et al. 2007) and ALADIN-CLI-MATE (Syrakov et al. 2010). The first model was cou-pled offline to the chemistry transport model CAMx(www.camx.com), the second one to the modelCMAQ (www.cmaq-model.org).

    52

  • Huszar et al.: Climate change increases ozone and PM levels

    Four domains with a horizontal resolution of 10 10 km were set up to cover the targeted areas (sizesof grids [no. of columns no. of rows; unitless] inparentheses): the larger central European regioncentering on the Czech Republic (183 162); Poland(118 107); Hungary (118 98); and Bulgaria (54 40). These domains and their corresponding runsare referred to as Czech, Polish, Hungarian and Bulgarian domains. The RegCM3/CAMx couple wasapplied over the first 3 domains. The Bulgariandomain was computed by the ALADIN-CLIMATE/CMAQ couple, as an alternative. The Czech domaindominated in size and encompassed almost all otherdomains. Evaluating the environmental changes withseveral model configurations and 1 additional modelcouple helps to increase the robustness of the results.Throughout the paper, if not mentioned explicitly,the Czech domain will be considered.

    Four decadal simulations were performed using theabove-mentioned models and their couples over eachdomain. The present decade (19912000) was simu-lated twice, with different meteorological forcing:ERA-40 reanalysis and ECHAM5 as a global climatemodel (GCM)-driven control experiment. These 2 runswill be referred to hereafter as the ECHAM and ERAruns, respectively. Since the ERA40 reanalysis project(Uppala et al. 2005) is a global atmospheric analysis ofobservations and satellite data streams, it can be con-sidered to be closer to real atmospheric conditionsand thus is used as the reference run for modellingsystem validation. The control simulation (ECHAMrun) for the same decade gave a basis for comparisonbetween present and future. Finally, 2 runs forced byECHAM5 model fields were performed for the de -cades 20412050 and 2091 2100, which we will referto as near and far future decades, respectively. Themeteorological runs were part of longer, 40 yr simula-tions starting in the years 1961, 2011 and 2061 forthe 3 analyzed decades. The chemistry was integratedfrom 1990, 2040 and 2090, allowing a 1 yr spin-up time.

    The model RegCM3 was run over 23 layers reach-ing 10 hPa, while CAMx ran over the lowermost12 levels only. For convective parameterisation, theGrell scheme was applied (Grell 1993). In the chem-istry model, we invoked the Carbon Bond IV chemi-cal mechanism (Carter 1996). Aerosol processes weretreated by the ISORROPIA thermodynamic equilib-rium model (Nenes et al. 1998). A meteorologicalpreprocessor utility (RegCM2CAMx; described andapplied by e.g. Krger et al. 2008, Katragkou et al.2010) was developed to convert RegCM3 outputfields to fields that CAMx requires for driving itstransport, diffusion, deposition and chemistry.

    Hourly anthropogenic emissions were obtainedfrom the European Monitoring and Evaluation Pro-gramme (EMEP) database (Vestreng et al. 2005) witha combination of 5