1. Welcome to the 3 rd GEOS-Chem Users’ Meeting! Thanks to HUCE, NASA/ACMAP, NSF-ATM for providing travel support; to Harvard SEAS, Brenda Mathieu, Jacob graduate students for logistics Meeting objectives: To report on science enabled by GEOS-Chem To share model experiences To guide future model direction To meet each other and develop collaborations The GEOS-CHEM user community with also many members of the broader atmospheric chemistry community

2. GEOS-Chem Chemical Transport Model (CTM) Research tool for understanding global/regional atmospheric composition –atmospheric composition in the broadest sense –low bar for scientific innovation combined with tight model traceability and version control Tool to contribute to broader activities –assessments (GMI), satellite retrievals, regional air quality models (CMAQ), chemical data assimilation (GMAO), climate models (GISS), Earth system models (through ESMF) Grass-roots community model –benefits from large international user community with broad range of interests; development is driven by grass-roots scientific needs –no access restrictions, but user participation and responsibility are key –bureaucracy kept to minimum solves 3-D continuity equations for atmospheric chemicals on global Eulerian grid using NASA/GMAO GEOS meteorological data

3. Functioning of GEOS-Chem Community Model Scientist (Jacob) is responsible for code integrity setting development priorities in consultation with users relationships in user community, issues of general benefit supporting core operations – funding from NASA/ACMAP Model Engineer (Yantosca) is responsible for version control, code updates user support software relationships with partner models Users are responsible for maintaining communication with other users (web site, users’ meeting) keeping contact with standard model and updating regularly to latest version providing mature new codes and data sets to standard model giving credit to recent developers through coauthorships REMEMBER: GEOS-Chem IS OWNED BY ITS USERS!

4. GEOS-Chem STANDARD MODEL: CURRENT CAPABILITIES Driven by GEOS-3/4 meteorology, 1985-present; also GISS GCM 3 output for 2000-2100 1 o x1 o -4 o x5 o horizontal resolution, up to 72 vertical levels Tropospheric ozone-NO x -CO-VOC-aerosol chemistry, off-line spin-offs, CO 2, CH 4, mercury Major updates since 2 nd Users’ Meeting (April 2005): 1. New capabilities: mercury (Eckley, Strode), CO 2 (Suntharalingam) 2. Anthropogenic emissions: NEI 99 (Hudman), EDGAR (van Donkelaar), EMEP (Auvray), BRAVO (Park, Boersma), Streets for China (Yantosca), IPCC future emissions (Wu) 3. Biomass burning emissions: GFED2 (Kasibhatla) 4. Natural emissions: MEGAN VOC (Fu), DEAD+GOCART dust (Fairlie), lightning rescaling (Murray, Hudman) 5. Chemistry: ISORROPIA aerosol thermodynamics (Park, Alexander), heterogeneous chemistry (Evans, Sauvage), isoprene SOA (Henze), dynamic tropopause (LeSager)

5. GEOS-Chem STANDARD MODEL: MATURE DEVELOPMENTS IN THE PIPELINE GEOS-5 meteorological data – needed to keep current, will enable 0.5 o x0.625 o horizontal resolution (Y.X. Wang, Yantosca) Linoz stratospheric ozone (Jones) Anthropogenic emissions : updates for recent years (Logan/van Donkelaar), ships (Murray), aromatics (Fu), acetylene (Xiao), agriculture (Y.X. Wang), diurnal biomass burning (Y. Chen) Improved lightning rescaling (Sauvage, Murray, /Hudman) H 2 /HD simulation (Jaegle) Random cloud overlap for photolysis (H. Liu) Methyl chloride simulation (Yoshida)

6. GEOS-Chem STANDARD MODEL: DEVELOPMENTS OVER THE HORIZON Next 1-2 years: Model adjoint (Sandu, Henze, Kopacz) Nested model capability for GEOS-5 (Y.X. Wang, D. Chen) Mercury: land biogeochemistry (Eckley, Downey), atmosphere- ocean coupling (Sunderland, Jaegle), halogens (Holmes) Spatial reduction algorithm (LeSager, Rastigeyev) Sulfate aerosol phase transitions (J. Wang) Updated methane simulation (Drevet) Improved dust chemistry (Fairlie, Solmon) Dicarbonyl SOA chemistry (M. Fu) Improved oxygenated VOCs (Millet, M. Fu) Next 2-4 years: Aerosol microphysics (Yu, Trivitayanurak) ECMWF meteorological input (Palmer) ESMF/MPI (Yantosca) POPs (Dachs) Carbonyl sulfide (Suntharalingam) Martian atmosphere (H. Wang)