1. SciDAC Fast Chemical Mechanism LLNL Philip Cameron-Smith Peter Connell Cathy Chuang (John Taylor) Keith Grant (Doug Rotman) NCARJean-Francois Lamarque Stacy Walters Francis Vitt ORNLDave Erickson Part of this work was performed under the auspices of the U. S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.

2. Fast-mechanism is designed for long climate simulations, NOT atmospheric chemists.  CH 4 – CO – O 3 – SO 4 mechanism  28 Species.  Troposphere & Stratosphere.  Unadulterated (so far).  Good simulation of O 3 and SO 4 (radiative species).  Over 100 years of simulation in various configurations (with and without feedback).  3 times faster than full (NMHC) mechanism. Fast = 3x CAM (ie, +200%) Full = 6x CAM (ie, +500%)

3. Half of chem time is advection. Tracers scale as 2-3% of CAM/tracer

4. Species in Fast Mechanism ( 1) O3 ( 2) O ( 3) O1D (O) ( 4) OH (HO) ( 5) HO2 ( 6) H2O2 ( 7) N ( 8) N2O ( 9) NO ( 10) NO2 ( 11) NO3 ( 12) N2O5 ( 13) HONO (HNO2) ( 14) HNO3 ( 15) HO2NO2 (HNO4) ( 16) CO ( 17) CH4 ( 18) CH2O ( 19) HCOOH (CH2O2) ( 20) CH3O2 ( 21) CH3O3 ( 22) CH3OOH (CH4O2) ( 23) CH3O2NO2 (CH3O4N) ( 24) DMS (C2H6S) ( 25) H2S ( 26) MSA (CH4O3S) ( 27) SO2 (O2S) ( 28) SULFUR6 (S)

5. Ozone - Ozonesondes

6. Ozone – Aircraft Campaigns

7. Ozone – Surface

8. OH - Spivakovsky

9. Chemical Lifetimes (integrated measure of OH)  CH 3 CCl 3 = 4.7 years (Fast), 6.5 (Full) 6.1 +/-0.1 (Obs).  CH 4 = 8.5 years (Fast), 11.8 (Full), 10-11 (Obs).  Prod(O 3 ) =3424 Tg(O 3 )/year (Fast)  Loss (O 3 ) = 3368 Tg(O 3 )/year (Fast)  Net (O 3 )= 56 Tg(O 3 )/year (Fast)

10. SO4 – Ocean Site Comparison.

11. SO4 – IMPROVE surface comparison

12. Sulfur Budget Tg(S) SO 2 SO 4 [H 2 O 2 ] [O 3 ] [OH] Emission68.38 Production14.2723.233.458.84 Dry Dep-36.18-3.12-0.69-1.39 Wet Dep-11.01-20.11-2.76-7.46 Chem. Loss-35.45 Net0.01 Mean Burden0.160.550.060.22

13. CH2O – Aircraft Campaigns

14. CH 3 OOH – Aircraft Campaigns

15. DMS – Aircraft Campaigns

16. H2O2 – Aircraft Campaigns

17. HNO3 – Aircraft Campaigns

18. NOx – Aircraft Campaigns

19. CO – Surface samples

20. Fast mechanism works in stratosphere (in IMPACT, but not CAM) Compact mechanism. Own ozone field for photolysis rates. Compact mechanism. Ozone climatology for photolysis rates. Full mechanism. Own ozone field for photolysis rates.

21. Fast mechanism works in stratosphere (in IMPACT, but not CAM) Ratio of zonal mean ozone in July for compact chemistry runs to full chemistry run (i.e., A/C and B/C).

22. Future Improvements  Family advection (eliminate 30% of tracer advection).  Implement Fast-J photolysis and/or TUV.  If necessary: Scale species (e.g. CO) to compensate for missing species.  Fix Stratosphere.  Add simplified NMHC chemistry.

23. Fast-mechanism is well positioned for AR5  CH 4 – CO – O 3 – SO 4 mechanism.  Troposphere & Stratosphere.  Good simulation of O 3 and SO 4 (radiative species).  Over 100 years of simulation in various configurations (with and without feedback).  3 times faster than full (NMHC) mechanism.  Further performance improvements under way. Fast = 3x CAM (ie, +200%) Full = 6x CAM (ie, +500%)

24. The End

25. Justification for interactive chem & aerosols Metric: Cycles spent going from specified fields to interactive chem/aerosols is more valuable than spending those cycles elsewhere. Justification areas:  Climate impact.  Mean climate  Variability  Importance to other WGs.  Model validation.  Air quality.  Climate change detection.  Online more efficient than off-line boot strapping.