1. Chemistry-climate interactions: a new direction for GEOS-CHEM 199320032050 GEOS-CHEM research to date GCAP project Current project: drive GEOS-CHEM into the future with GISS GCM III.

2. CACTUS (Chemistry, aerosol, climate: Tropospheric unified simulation) Collaborators: Caltech, GISS, Irvine, Carnegie Mellon, Georgia Tech GISS GCM II’ GHGs, solar flux, land surface, etc. CalTech aerosol module Harvard chemistry module meteorology emissions oxidants, nitric acid aerosol ozone emissions Previous chemistry-climate work at Harvard used the CACTUS model. aerosol

3. Standard model Observations Adjusted model Best match with observed surface ozone: Increased isoprene emissions by 50% Lightning NOx scaled to 1.0 Tg/y GEOS-CHEM studies of natural emissions are consistent with studies of preindustrial ozone in CACTUS model. Mickley et al., 2001

4. In 2003, we started GCAP (Global Climate and Air Pollution). collaborators: David Streets, John Seinfeld, David Rind, Joshua Fu Number of summer days with 8-hour ozone > 84 ppbv, average for northeast U.S. sites 1988, hottest on record days Many meteorological factors control air quality, e.g.: Temperature Ventilation Circulation patterns Rainfall Cloudiness Basic question: how will surface air quality respond as climate changes? Lin et al., 2001 Work so far: CACTUS model with tracers of anthropogenic pollution.

5. GCAP approach : archive met fields from GISS GCM and apply to GEOS-CHEM 1950 2000 2025 2050 2075 2100 23L GISS GCM (Model 3), with changing GHGs Spin-up of ocean GEOS-CHEM Calculates chemistry, aerosol precursor emissions archived temperatures, humidity, winds, etc CMAQ regional model

6. GCAP Progress 1950 2000 2025 2050 2075 2100 23L GISS GCM (Model 3), with changing GHGs Spin-up of ocean GEOS-CHEM precursor emissions archived temperatures, humidity, winds, etc CMAQ regional model New version frozen Future emissions prepared Interface completed Validation ongoing Interface ~done

7. New EPA-STAR project, 2005: “GCAP + Fire” collaborators: Jennifer Logan, David Diner, Daewon Byun How will changing fire frequency in the future affect surface air quality? 1950 2000 2025 2050 2075 2100 23L GISS GCM with fire prediction scheme Spin-up of ocean GEOS-CHEM Calculate chemistry, aerosol precursor emissions archived met fields and areas burned CMAQ regional model

8. To be continued with Shiliang’s talk at 5:15

9. Progress so far New version of GISS GCM 23-layer received (Model III), includes new boundary layer scheme. (David Rind). Tracers tested in Model III (David Rind). GISS meteorological fields implemented into GEOS-CHEM. (Loretta Mickley, Shiliang Wu) GEOS-CHEM results for present-day validated. (Shiliang Wu). Interface between GEOS-CHEM and CMAQ tested. (Joshua Fu). Future emission inventories completed. (David Streets).

10. GCAP continued... 23L GISS GCM, with changing GHGs GEOS-CHEM archived met fields 1950 2000 2025 2050 2075 2100 Spin-up of ocean 2000 2025 2050 2075 2100 1. Develop future climatology for ozone and aerosols 2. Recalculate meteorology with ozone, aerosol trends