1. March 31, 2004BGC Working Group Interactive chemistry in CAM Jean-François Lamarque, D. Kinnison and S. Walters Atmospheric Chemistry Division NCAR

2. March 31, 2004BGC Working Group Goal Provide a flexible framework for the study of chemistry-climate interactions in CCSM, including land/ocean interactions Include gas-phase and aerosols Focus on the troposphere and stratosphere

3. March 31, 2004BGC Working Group 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 31, 2004BGC Working Group 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 31, 2004BGC Working Group Current status Implementation in WACCM of combined tropospheric (regional and global scale) 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 fixed SST

6. March 31, 2004BGC Working Group 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 31, 2004BGC Working Group Mid-tropospheric ozone

8. March 31, 2004BGC Working Group Model evaluation Comparison with tropospheric and stratospheric observations Comparison with TOMS total ozone column

9. March 31, 2004BGC Working Group Comparison with observations (1) Carbon monoxide (ppbv) Barrow, AlaskaBlack sea, Romania Mauna Loa, HawaiiHalley station, Antarctica Red : model results Blue : observations Month

10. March 31, 2004BGC Working Group Comparison with observations (2) Ozone mixing ration (ppbv) Month

11. March 31, 2004BGC Working Group Comparison with observations (3) NO x = NO + NO 2

12. March 31, 2004BGC Working Group Comparison with observations (4)

13. March 31, 2004BGC Working Group 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

14. March 31, 2004BGC Working Group 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)

15. March 31, 2004BGC Working Group 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