1. March 9, 2004CCSM AMWG Interactive chemistry in CAM Jean-François Lamarque, D. Kinnison S. Walters and the WACCM group Atmospheric Chemistry Division NCAR

2. March 9, 2004CCSM AMWG Goal Provide a flexible framework for the study of chemistry-climate interactions in CCSM Focus on the troposphere and stratosphere

3. March 9, 2004CCSM AMWG Computational approach Chemical scheme is input in a preprocessor that creates a set of subroutines added to the standard CAM Reads a set of external files (for emissions, deposition velocities and photolysis rates) Uses the finite volume dynamical core for the advection of tracers Convective and diffusive transport of tracers is considered

4. March 9, 2004CCSM AMWG Main features Photolysis and chemical reactions solved with an implicit/explicit set of solvers Lookup table photolysis rates, including cloud correction (but not aerosols) Wet (first-order loss linked to precipitation in CAM) and dry removal Surface emissions (fixed, monthly averages) Lightning NO production linked to convection in CAM

5. March 9, 2004CCSM AMWG Current status Implementation in WACCM of combined tropospheric (valid for regional and global scale chemistry) and stratospheric chemistry (including PSCs) : 105 species, over 300 chemical reactions Simulations performed with 52 levels, extending up to 85 km. Stratosphere-troposphere flux is explicitly calculated Horizontal resolution of 2x2.5 25 years of present-day simulations, using climatological SST

6. March 9, 2004CCSM AMWG Performance In the present configuration, inclusion of chemistry (including transport of tracers) approximately doubles the cost of the equivalent WACCM simulation; this ratio will be a little worse for CAM On bluesky, 96 CPUs, 1 year in 2 days

7. March 9, 2004CCSM AMWG Mid-tropospheric ozone

8. March 9, 2004CCSM AMWG Mid-tropospheric ozone

9. March 9, 2004CCSM AMWG Model evaluation Comparison with tropospheric and stratospheric observations Comparison with TOMS total ozone column

10. March 9, 2004CCSM AMWG Comparison with observations (1) Carbon monoxide (ppbv) Barrow, AlaskaBlack sea, Romania Mauna Loa, HawaiiHalley station, Antarctica Red : model results Blue : observations Month

11. March 9, 2004CCSM AMWG Comparison with observations (2) Ozone mixing ration (ppbv) Month

12. March 9, 2004CCSM AMWG Comparison with observations (3) NO x = NO + NO 2

13. March 9, 2004CCSM AMWG Comparison with observations (4)

14. March 9, 2004CCSM AMWG Summary Working version of interactive tropospheric/stratospheric chemistry Analysis of results indicate a good overall representation of the chemistry in the atmosphere Biases are similar to the ones found in MOZART results, on which the chemistry is based

15. March 9, 2004CCSM AMWG Next steps (1) Develop a CAM version (requires the addition of upper-boundary conditions); expected to happen within a month Inclusion of aerosols (ammonium, sulfate, sea-salt, dust,organic and black carbon; X.X. Tie, P. Hess N. Mahowald and P. Rasch) Better representation of wet removal (P. Hess and P. Rasch) Interactions with CLM (deposition; emissions of BVOCs (C. Wiedinmyer and S. Levis); soil NO)

16. March 9, 2004CCSM AMWG Next steps (2) Interactive calculation of photolysis rates Development of a variety of chemical packages for ease of use Coupling with ocean biogeochemistry Coupling between the nitrogen and the carbon cycle through CLM (P. Thornton) Interactive emissions from wetlands