1. Effects of Global Change on Air Quality in the United States Shiliang Wu, Harvard 2 nd GEOS-CHEM users’ meeting Apr 5, 2005 Look into the Future with GEOS-CHEM ---

2. Global Change and Air Pollution (GCAP) A collaborative interdisciplinary project involves groups from Harvard, Caltech, NASA/GISS, DOE/ANL, U.Tenn. Harvard Team: Daniel Jacob, Loretta Mickley, Shiliang Wu Great thanks Bob Yantosca for supportive work!

3. What will influence the future air quality? CTM 1. Emission 2. Meteorology Winds Convective mass flux Strat-influx

4. Meteorological control of air quality (case of 210 Pb) July mean surface concentration of 210 Pb (fCi/SCM)

5. Air Quality Pollutants concentration & distribution Chemistry, transport, deposition, etc Frame structure Natural Emissions Anthropogenic Emissions Pollutants & precursors GHG Climate Radiative forcing

6. Difference b/w GISS and GEOS – Vertical grids GEOS_3: 48 layers GEOS_4: 55 layers GISS II’: 23 layers

7. Difference b/w GISS and GEOS -- Horizontal grids 46 bins 45 bins GEOS 4x5GISS 4x5 GISS - “B” GridGEOS - “A” Grid ( shift in both latitude and longitude direction )

8. Difference b/w GISS and GEOS -- Convection Schemes GEOS_3GEOS_4GISS Updraft Entraining Updraft Non-entraining Updraft N/ADowndraft Entraining Downdraft Non-entraining Downdraft DetrainmentEntrainment Entraining Detrainment Non-entraining Detrainment

9. Different met-fields  Different results expected

10. Natural emission sensitive to met-fields

12. Lightning emission sensitive to met-fields

13. Afternoon tracer conc. over U.S. (surface layer)

14. Afternoon tracer conc. over U.S. (zonal mean)

15. Validation against ozonesonde data ( July monthly mean )

16. Conclusions 1. The performance of the GCAP model looks good and should be capable of the mission. 2. There still might be (minor) improvements in the near future. 3. GEOS-CHEM is (to some extent) flexible and easy going.

17. Thank you!