Evaluating the impact of climate change on European air quality

Scientists from the Laboratory of Atmospheric Physics (School of Physics) and the Department of Meteorology and Climatology (School of Geology) have simulated the regional climate-air quality over Europe for two future decades (2041-2050 and 2091-2100) using the HellasGrid Infrastructure and the EGI Grid, with the support of the Scientific Computing Center at A.U.Th..

The computational models used for these simulations are the regional climate model RegCM3 and the air quality model CAMx, which have been off line coupled in this case (Figure 1). The control simulation for the decade 1991-2000 was performed twice, once externally forced by the ERA40 reanalysis and once using the global circulation model ECHAM5, in order to investigate the importance of external meteorological forcing on air quality (Katragkou et al., 2010). The RegCM3 model was forced by ECHAM5 under the A1B emission scenario for two future time slices, namely 2041-2050 and 2091-2100. These simulations served as a theoretical experiment of evaluating the impact of climate change on air pollution (Katragkou et al., 2011).

For each decadal simulation the computation consumed approximately 1000 CPU hours. CAMx simulations were performed on SMP machines as the model has been intrinsically parallelized with the OpenMP library. Using this feature of the CAMx model a significant reduction on the overall computation time was feasible.

In terms of storage, the resources required for archiving the CAMx output files are estimated to slightly more than 5TB.

Off-line coupling of RegCM3 and CAMx computational models

Figure 1: A schematic illustrating an outline of the modelling system RegCM3/CAMx applied in this study (from Zanis et al., 2011)

Surface ozone simulated by RegCM3/CAMx was evaluated against ground based measurements from the European database EMEP (Zanis et al., 2011). The air quality simulations available at AUTH for the three time slices (1991-2000, 2041-2050 and 2091-2100) over Europe with a resolution of 50 Km have been provided as air quality boundaries for higher resolution air quality simulations over sub-European grids (Huszar et al., 2011).

The results suggest that changes imposed by climate change until the 2040s in surface ozone concentration during summer will be below 1 ppbv (parts per billion by volume) . By the 2090s, however, changes are foreseen to be more significant especially over south-west Europe, where the median of near surface ozone has been found to increase by 6.2 ppbv.

Near surface ozone concentrations over Europe

Figure 2: Average summer surface ozone for the control simulation 1991-2000 (left). Differences in simulated average summer ozone between 2091-2100 and control simulation (right). The grey color corresponds to non-statistical significant differences (from Katragkou et al., 2011)

The median of summer near surface temperature for Europe at the end of the 21st century was calculated at 2.7K higher than the end of the 20th century with more intense temperature increase simulated for southern Europe. A prominent outcome was the decrease of cloudiness mostly over western Europe at the end of the 21st century associated with an anticyclonic anomaly which favours more stagnant conditions and weakening of the westerly winds (Katragkou et al., 2011).

Mean temperature differences

Figure 3: Mean differences between second future decade (2091-2100) and the present decade (1991-2000) for summer in the fields of surface temperature (left) and geopotential height at 500 hPa (right).The red contours correspond to geopotential height at 500 hPa during the control decade (from Katragkou et al., 2011).

This work has been accomplished in the framework of the FP6 European Project CECILIA (Central and Eastern Europe Climate Change Impact and Vulnerability Assessment, Contract Nr 037005). The results were produced on the EGI and HellasGrid infrastructure with the support of the Scientific Computing Center at the Aristotle University of Thessaloniki (AUTH). The results of this work have been published in peer-review journals (see references), presented in several national and international conferences and awarded by the Hellenic Meteorological Society (2008), the European Association for the Science of Air Pollution (2009) and the Research Committee of the Aristotle University of Thessaloniki (2010).

Contact details:

  • Dimitris Melas (PI), Associate Professor, AUTH, melas (at) auth.gr
  • Prodromos Zanis, Assistant Professor, AUTH, zanis (at) geo.auth.gr
  • Eleni Katragkou, Lecturer, AUTH, katragou (at) auth.gr
  • Scientific Computing Center, AUTH, contact (at) grid.auth.gr

References:

  1. Huszar P., K. Juda-Rezler, T. Halenka, H. Chervenkov, D. Syrakov, B. C. Krueger, P. Zanis, D. Melas, E. Katragkou, M. Reizer, W. Trapp, M. Belda, Potential climate change impacts on ozone and PM levels over Central and Eastern Europe from high resolution simulations, Climate Research (in press), 2011
  2. Katragkou Ε., P. Zanis, I. Tegoulias, D. Melas, I. Kioutsioukis, B. C. Krüger, P. Huszar, T. Halenka, S. Rauscher, Decadal regional air quality simulations over Europe in present climate: near surface ozone sensitivity to external meteorological forcing, Atmospheric Chemistry and Physics, 10, 11805-11821, 2010
  3. Κatragkou E., P. Zanis, I. Kioutsioukis, I. Tegoulias, D. Melas, B.C. Krüger, E. Coppola, Future climate change impacts on summer surface ozone from regional climate-air quality simulations over Europe, J Geophys Res (in press), 2011
  4. Zanis P., E. Katragkou, I. Tegoulias, A. Poupkou, D. Melas, Evaluation of near surface ozone in air quality simulations forced by a regional climate model over Europe for the period 1991-2000, Atmospheric Environment, 45, 6489-6500, 2011