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SciDAC Fast Chemical Mechanism. LLNL Philip Cameron-Smith Peter Connell Cathy Chuang (John Taylor) Keith Grant (Doug Rotman) NCAR Jean-Francois Lamarque Stacy Walters Francis Vitt ORNL Dave Erickson
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SciDAC Fast Chemical Mechanism LLNL Philip Cameron-Smith Peter Connell Cathy Chuang (John Taylor) Keith Grant (Doug Rotman) NCAR Jean-Francois Lamarque Stacy Walters Francis Vitt ORNL Dave 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.
Fast-mechanism is designed for long climate simulations, NOT atmospheric chemists. • CH4 – CO – O3 – SO4 mechanism • 28 Species. • Troposphere & Stratosphere. • Unadulterated (so far). • Good simulation of O3 and SO4 (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%)
Half of chem time is advection. Tracers scale as 2-3% of CAM/tracer
Species in Fast Mechanism ( 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) ( 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
Chemical Lifetimes (integrated measure of OH) • CH3CCl3 = 4.7 years (Fast), 6.5 (Full) 6.1 +/-0.1 (Obs). • CH4 = 8.5 years (Fast), 11.8 (Full), 10-11 (Obs). • Prod(O3) = 3424 Tg(O3)/year (Fast) • Loss (O3) = 3368 Tg(O3)/year (Fast) • Net (O3) = 56 Tg(O3)/year (Fast)
Sulfur Budget Tg(S) SO2 SO4 [H2O2] [O3] [OH] Emission 68.38 Production 14.27 23.23 3.45 8.84 Dry Dep -36.18 -3.12 -0.69 -1.39 Wet Dep -11.01 -20.11 -2.76 -7.46 Chem. Loss -35.45 Net 0.01 Mean Burden 0.16 0.55 0.06 0.22
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.
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).
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.
Fast-mechanism is well positioned for AR5 • CH4 – CO – O3 – SO4 mechanism. • Troposphere & Stratosphere. • Good simulation of O3 and SO4 (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%)
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.