1. Origin and distribution of ozone in the Eastern Mediterranean - Results with GEOS-CHEM simulations Origin and distribution of ozone in the Eastern Mediterranean - Results with GEOS-CHEM simulations Christos Giannakopoulos and Philippe LeSager National Observatory of Athens Anna Protonotariou and Maria Tombrou University of Athens

2. Group research aims Quantify the export and chemical evolution of radiatively and chemically important trace gases and aerosols from Europe to the Eastern Mediterranean. Quantify the impact of European pollution on the Eastern Mediterranean Elucidate mechanisms and pathways associated with the transport and transformation of these trace chemicals Characterize the air masses entering Greece and Eastern Mediterranean Comparison of measured chemical fields from airborne experiments with those predicted by the model.

3. Model setup Run GEOS-CHEM (v5-04) at 4 o x5 o with 30 vertical levels 6 months of spinup time 1 year run to obtain results for year 2001 (GEOS-3) 2001 selected since MINOS (Mediterranean Intensive Oxidant Study) campaign - coordinated by MPI-Chemistry took place in summer over the East Med.

4. Model Runs To quantify the origin of ozone pollution several simulations conducted: standard simulation simulation with European emissions set to zero simulation with N.American emissions set to zero simulation with African emissions set to zero simulation with Asian emissions set to zero

5. Ground level ozone In January lower levels of ozone are evident in the region due to reduced photechemistry. Typical values are ~25 ppbv in the East Med. In July higher values are evident. Typical values in the East Med ~40ppb. In East Med the highest ground level ozone in Europe.

6. Model performance-Surface Compared with EMEP obs. in Crete GEOS performs well but fails to capture well the higher values of the prob. distribution. GEOS underestimates. When Europe is off, no elevated ozone levels - amount generally always 40ppbv (background ozone). N.America seems to contribute 10ppbv in the high ozone values.

7. Ozone - Upper Troposphere No great differences in ozone abundances in East Med. In July slightly more elevated ozone levels in UT.

8. Model performance-Upper Trop In the UT, Europe emissions have no contribution. North America emissions contribute to the low ozone values with the Westerly circulation Asian emissions contribute to elevated ozone values due to the Easterly monsoon in warm period of the year

9. Model performance-Middle Trop In the Middle Troposphere, North American emissions contribute to the high ozone values of ozone European and African emissions have a contribution to the middle range of values

10. Future research directions Focus on ozone precursors too. Compare GEOS results with flight data from MINOS to evaluate performance in middle and upper troposphere Integrate the model to a finer resolution (2 o x2.5 o ) Develop the nesting capability for the Mediterranean region (1 o x1 o )