1. Chemistry-climate working group 2013-2017 Co-chairs: Hong Liao, Shiliang Wu The 7th International GEOS-Chem Meeting (IGC7)

2. Chemistry-climate interactions Climate Atmospheric Chemistry Atmospheric Chemistry Ecosystems Interactions on interannual, decadal, or centennial time scales Radiative forcing by GHGs, O 3, and aerosols Changes in emissions, chemical reactions, transport, and deposition Deposition of O 3, N, S, etc. Biogenic VOCs, fire emissions, etc. Impacts on land cover, etc. Carbon cycle, etc.

3. Assimilated meteorology GEOS-4, GEOS-5, MERRA GEOS-Chem Land cover model Archived meteorology Fire prediction model Climate models Model frameworks 1. Standard 2. Global Change and Air Pollution (GCAP) Impacts of climate change on land cover (biogenic emissions), fire emissions, and atmospheric chemistry. Impacts of climate variability on atmospheric chemistry on interannual to decadal time scales. GEOS-Chem

4. The standard GEOS-Chem has been used to understand historical changes in atmospheric Chemistry To quantify the variations in chemical species; To understand the drivers (meteorological parameters vs. emissions) of the variations of different species; To help with the interpretation of year-by-year variations in measurements; To assess the effectiveness of short-term air quality control strategies. Mu and Liao, 2014 Yang et al., 2014 Yang et al., 2015

5. The GCAP model framework can be used to investigate past and future atmospheres Three versions of GCAP are available: 1. GISS Model 3 + GEOS-Chem (4 o x 5 o, by Loretta Mickley in year 2003) 2.GISS Model E + GEOS-Chem (2 o x 2.5 o or 4 o x 5 o, by L. T. Murray and E. M. Leibensperger in year 2014) 3. CESM + GEOS-Chem (2 o x 2.5 o, by Rokjin Park in year 2014)

6. GCAP has been used extensively for projection of future air quality  1. GCAP: Future changes in air quality and tranboundary transport Wang et al., 2013; Jiang et al., 2013; Wai et al., 2014  2. GCAP + changes in land cover Wu et al., 2012; Tai et al., 2013.  3. GCAP + changes in fire emissions Yue et al., 2013; 2014 2000-2050 increase in surface ozone over Asia due to changes in emissions + climate. Wang et al., 2013. 2050s – present-day

7. Past fire emissions Sensitivity of biogenic isoprene emissions to atmospheric [CO 2 ] Isoprene photochemistry HO 2 uptake by aerosols Lightning NO x emissions Murray et al., 2014; Achakulwisut, in review.  [GHGs]  Orbital parameters  Topography  Sea ice extent  Sea surface temp. Climate GISS Model E GCM Meteorological fields for 4 time-slices: Present day: ca. 1990s Pre-industrial: ca. 1770s warm LGM: ~ 21ka cold LGM: ~ 21ka GCAP2 has been applied to paleo- and preindustrial simulations

8. GCAP3 GACP 3 has been used to study future O 3 and oxidants under the RCPs Kim et al., 2015 RCP2.6 O 3 2050-2000RCP4.5 O 3 2050-2000 RCP6.0 O 3 2050-2000RCP8.5 O 3 2050-2000

9. Updates in GEOS-Chem that are important for chemistry-climate  Online radiative transfer model --- The Rapid Radiative Transfer Model for GCMs (RRTMG) has been coupled online with the GEOS-Chem model as described by Heald et al. (2014); --- The RRTMG solves the radiative transfer equation in shortwave bands and 16 longwave bands that cover from 230 nm through 56 μm.  RCP future emission scenarios in GEOS-Chem (Holmes et al., 2013) Heald et al. (2014)

10. Future directions: The two-way coupling of chemistry-climate 1.Coupling of the grid-independent GEOS-Chem with climate models will allow us to easily link chemistry with climate, vegetation, ocean biology, fire, carbon cycle. 2.On-line interface between GEOS-Chem and the Goddard Earth Observing System (GEOS) Earth System Model from the NASA Global Modeling and Assimilation Office (GMAO) is ready, using the Earth System Modeling Framework (ESMF); 3.Can the GEOS-Chem simulations be conducted on any model grid and interfaced with any ESM?