1. CMAS Conference 2011 Comparative analysis of CMAQ simulations of a particulate matter episode over Germany Chapel Hill, October 26, 2011 V. Matthias, A. Aulinger, M. Quante, C. Chemel, J. L. Perez, R. San Jose, R. Sokhi

2. Volker Matthias, Oct 26, 20112 Case study on PM10 (Feb/March 2003) Stern et al., Atm. Env. 42, 4567-4588 (2008) PM10 daily mean concentration (µg/m 3 ) over Germany on March 2, 2003

3. Volker Matthias, Oct 26, 20113 COST 728 study COST 728: European cooperation, participants from more than 20 nations „Enhancing Mesoscale Meteorological Modelling Capabilities for Air Pollution and Dispersion Applications“

4. Volker Matthias, Oct 26, 20114 GroupMet-ModelCTM IfK, HZGMM5CMAQ Uni Hertfordshire (UH)WRFCMAQ TU Madrid (UPM)MM5CMAQ CMAQ model intercomparison

5. Volker Matthias, Oct 26, 20115 What are the differences?  Preparation of the emissions  Meteorological fields  Inital and boundary conditions  Grids (horizontal and vertical structure)  Computing platforms  People who run the model

6. Volker Matthias, Oct 26, 20116 Concept Round 1:  All groups provide input files (IC,BC,EMIS,METEO,GRIDDESC)  All groups use common CMAQ version (4.7) and chemistry mechanism (cb05_ae_aq)  All groups recalculate results of others Expected results:  Determination of simple (model user) errors (switches …)  Quantification of computing errors (compiler, platform, …)

7. Volker Matthias, Oct 26, 20117 Recalculations: Sulfate WesterlandMelpitz

8. Volker Matthias, Oct 26, 20118 WesterlandMelpitz Recalculations: Nitrate

9. Volker Matthias, Oct 26, 20119 Outcome: Recalculations  CMAQ model results can be reproduced by other groups on different computing platforms  Depending on species, some differences exist but they are much smaller than the differences in the “blind“ runs

10. Volker Matthias, Oct 26, 201110 Concept (2) Round 2: Agree on common grid Use same initinal and boundary conditions (IC & BC) Expected Results influence of emissions influence of meteorological fields

11. Volker Matthias, Oct 26, 201111 Impact of emissions Reconstruction of UH run Emission files from UPM Sulfate Nitrate

12. Volker Matthias, Oct 26, 201112 Emissions in Central Europe (spatial average) NOSO 2 NH 3 UH UPM HZG Time series from CMAQ input files

13. Volker Matthias, Oct 26, 201113 Outcome: Emissions  Emissions may be prepared in different ways concerning their temporal and spatial variation.  For short time series at certain grid points this may lead to significant differences in particle concentrations.

14. Volker Matthias, Oct 26, 201114 Impact of meteorology MM5 from UPM MM5 from HZG WRF from UHS Sulfate Nitrate

15. Volker Matthias, Oct 26, 201115 Outcome: Meteorology  Numerous meteorological parameters may influence particle concentrations.  The quality of the CTM results may not be judged from the quality of the meteorological fields.

16. Volker Matthias, Oct 26, 201116 Open questions Do we see „typical“ differences between „correct“ model runs or were there important errrors in the input data? Sensitivity study: Annual runs (year 2000) with CMAQ 4.6 with different  Boundary conditions  Emission files  Meteorological data Goal: Quantify the variability of the hourly and daily concentrations at Melpitz

17. Volker Matthias, Oct 26, 201117 Boundary conditions BC from global models: Mozart and TM4 SO 2 SO 4 NO 3

18. Volker Matthias, Oct 26, 201118 Emissions SMOKE-EU emissions and EMEP emissions Additional comparisons to other emission data sets with similar results SO 2 SO 4 NO 3

19. Volker Matthias, Oct 26, 201119 Meteorology MM5 (FDDA with NCEP) and CCLM (Spectral nudging with NCEP) Hourly values SO 2 SO 4 NO 3

20. Volker Matthias, Oct 26, 201120 CMAQ intercomparison: different emissions Nitrate values with UH emissions lower than it could be expected. SO 4 NO 3

21. Volker Matthias, Oct 26, 201121 CMAQ intercomparison: different meteorological fields Sulfate values with UPM and HZG meteo within expected range Nitrate values low, but may be explained by variability due to meteo input SO 4 NO 3

22. Volker Matthias, Oct 26, 201122 Summary CMAQ intercomparison within COST 728 showed:  Simulations are reproducable by other groups on other computing platforms  Emission data may be prepared in very different ways  Largest influence on simulation results comes from meteorology  Unreliable results may be detected by comparisons to sensitivity runs Acknowledgements Emission data has been prepared by Johannes Bieser Most CMAQ sensitivity runs were set up by Johannes Bieser Total gridded emissions were provided by TNO, IER and EMEP Boundary conditions were provided by the RETRO project (TM4) and Ulrike Niemeier (Mozart)

23. Volker Matthias, Oct 26, 201123 Thank you