ESF- MedCLIVAR Workshop Climate Change Modeling for the Mediterranean region, ICTP, Trieste, Italy, Oct 2008 Regional air quality decadal simulations over Europe in present and future climate Prodromos Zanis, Ass. Professor Department of Meteorology and Climatology, Aristotle University of Thessaloniki, Greece Contributors: E. Katragkou, I. Tegoulias, D. Melas, AUTH, Greece B. C. Krüger, BOKU-Met, Vienna, Austria P. Huszar and T. Halenka, CUNI, Prague, Czech Republic S. Rauscher, E. Coppola, ICTP, Trieste, Italy

Interest has more recently turned to the potential influence of climate change on future air-quality levels which can be seen in various ways: Warming will increase water vapor concentrations, and changes in temperature and water vapor will affect the reaction rates of many chemical conversions. Climate change may also alter global circulation dynamics, changing several processes that govern the distribution of tropospheric ozone, such as a) stratosphere-troposphere exchange, b) the distribution of convection, and c) ventilation of the boundary layer. Changes in climate will also affect many of the natural sources of trace gases, such as a) wetland CH4, b) biogenic volatile organic compounds, c) lightning NOx and d) soil NOx. Changes in climate will also affect wet-scavenging of fine particulate matter species which however is strongly dependent upon the predicted regional-scale precipitation changes.

Figure 1. Potential climate change effects on air-pollution and health (adapted by Bernard et al., 2001).

Climatic Initial & Boundary Conditions RegCM3 Climate Model Interface CAMx Photochemical AQ Model Pollutant concentrations Biogenic Emissions on-line calculated Anthropogenic Emissions Chemical Initial & Boundary Conditions Chemistry Parameters Photolysis Rates RegCM3 Resolution: 50 km x 50 km or 25 km x 25 km Vertical Layers: 18 (up to 50hPa) CAMx 4.40 Resolution: 50 km x 50 km Vertical Layers: 12 (up to 6.5 km) Chemistry Mechanism: CB(IV) + aerosol EMISSIONS: Anthropogenic: EMEP database Biogenic: On-line calculated (temp. + rad. dependent) CHEMICAL BOUNDARY CONDITIONS: Clean Modeling system

4 x10-year simulations of the RegCM3/CAMx offline system The regional climate model simulations of RegCM3 were used to drive off-line the air quality model CAMx for 4 decadal runs namely: a) with ERA-40 to drive RegCM3, (perfect BC run) b) with ECHAM5 to drive RegCM3, (control run) c) with ECHAM5 (under A1B scenario) to drive RegCM3 d) with ECHAM5 (under A1B scenario) to drive RegCM3 * Domain: European domain (ENSEMBLES) with 50 km x 50 km or 25 km x 25 km ** All the RegCM3 simulations for these time slices have been carried out by ICTP and provided to AUTH.

Comparison of RegCM3/ERA-40/CAMx with EMEP ozone for the whole year over the period Fractional Gross ErrorModified Normalized Mean Bias FGE ranges in the majority of stations between % while MNMB ±20 %. Satisfactory model performance is usually considered within the ranges of ± % for normalized bias and % for gross error according to US-EPA regulations (US EPA, 1991).

Sensitivity studies Winter Summer Sensitivity to NOx emissionsSensitivity to biogenic emissions

Comparison of ERA40/RegCM3/CAMx with ECHAM/RegCM3/CAMx over the period WINTER

Comparison of ERA40/RegCM3/CAMx with ECHAM/RegCM3/CAMx over the period Summer

Differences between and of ECHAM/RegCM3/CAMx Winter

Differences between and of ECHAM/RegCM3/CAMx Summer

Differences between and of ECHAM/RegCM3/CAMx Winter ?

Differences between and of ECHAM/RegCM3/CAMx Summer

Conclusions Validation with EMEP Evaluation of CAMx simulations showed that the modeling system has a satisfactory performance with respect to O3. ECHAM1990 – ERA40 The ozone differences are related to circulation changes modifying solar radiation and temperature fileds. ECHAM ECHAM1990 In summer, incoming solar radiation shows a substantial decrease throughout the whole domain, followed by a similar spatial behavior of O3 except SE Europe where Temperature and Biogenic emissions increase. In winter increased solar radiation leads to increased O3 concentrations only in the west and southern part of the domain. ECHAM ECHAM1990 Ozone increases in large parts of Europe for both winter and summer. The spatial patterns of ozone and solar radiation are very similar suggesting that solar radiation is the dominant modulating factor for ozone changes.

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