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Stratospheric chemistry and SMVGEAR II in GEOS-CHEM model

Stratospheric chemistry and SMVGEAR II in GEOS-CHEM model. Gabriele Curci University of L’Aquila. ROAD MAP. Role of the stratosphere in GEOS-CHEM model New capabilities of GEOS-CHEM: Full Stratospheric chemistry simulation SMVGEAR II chemistry ODE solver

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Stratospheric chemistry and SMVGEAR II in GEOS-CHEM model

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  1. Stratospheric chemistry and SMVGEAR II in GEOS-CHEM model Gabriele Curci University of L’Aquila 6/2/2003

  2. ROAD MAP • Role of the stratosphere in GEOS-CHEM model • New capabilities of GEOS-CHEM: • Full Stratospheric chemistry simulation • SMVGEAR II chemistry ODE solver • Tropospheric-Stratospheric chemistry simulation • First evaluation of new capabilities • Conclusions and development needs • Possible applications 6/2/2003

  3. STRATOSPHERIC CHEMISTRY IN CURRENT GEOS-CHEM Global sources and sinks of ozone (Tg O3 y-1) in GEOS-CHEM model NOx emissions (Tg N y-1) to the troposphere STRATOSPHERE 0.2 LIGHTNING 5.8 FOSSIL FUEL 23.1 SOILS 5.1 BIOMASS BURNING 5.2 BIOFUEL 2.2 AIRCRAFT 0.5 6/2/2003

  4. STRATOSPHERIC CHEMISTRY IN CURRENT GEOS-CHEM • In UPBDFLX_MOD stratospheric O3 (Synoz) and NOx fluxes are specified • Reactions with OH and photolysis of tracers are performed in SCHEM after call to SMVGEAR • Monthly mean stratospheric OH, J-values, Prod/Loss of CO and NOx are taken from Dylan Jones’ 2-D model It would be helpful a better simulation of stratospheric chemistry? 6/2/2003

  5. A STRATOSPHERIC CHEMISTRY VERSION OF GEOS-CHEM MAIN FEATURES OF THE MODEL • It shares with standard model: • Input met fields • Transport module • SMVGEAR chemistry ODE solver • Stratospheric chemistry mechanism derived from STRATAQ model from U. of L’Aquila [Grassi et. al, 2002] • 40 species, 120 kinetic reactions, 30 photolysis, 6 heterogeneous reactions • Heterogeneous chemistry on sulfate aerosol and PSCs • PSC sedimentation (denitrification) • 17 transported tracers + 8 long-lived species w/ fixed distribution (CH4, N2O, CFCs, CH3Cl, CH3Br…) • Computes J-values using “SLOW-J” algorithm 6/2/2003

  6. A STRATOSPHERIC CHEMISTRY VERSION OF GEOS-CHEM: EVALUATION Stratospheric GEOS-CHEM ozone column vs TOMS column (1998) 6/2/2003

  7. SMVGEAR II IN GEOS-CHEM MAIN FEATURES OF THE PACKAGE • Sparse-Matrix-Vectorized Gear type chemical ODE solver version 2 • Main differences vs. SMVGEAR version 1: • Allows for different chemistry sets in different regions of the atmosphere (e.g., urban, free troposphere, stratosphere) • Grid reordering according to stiffness for computational efficiency • A GEOS-CHEM 1-month run using SMVGEAR II reveals: • 20 min/day vs. 23 min/day on IBM/AIX platform • 10 h/month vs. 11.5 h/month on IBM/AIX platform • different concentrations 6/2/2003

  8. SMVGEAR II IN GEOS-CHEM: EVALUATION Relative differences between SMV1 and SMV2 simulations after 1 month NOx -1.6 ÷ 0.2 % 6/2/2003

  9. SMVGEAR II IN GEOS-CHEM: EVALUATION Relative differences between SMV1 and SMV2 simulations after 1 month Ox 0 ÷ 1.6 % 6/2/2003

  10. SMVGEAR II IN GEOS-CHEM: EVALUATION Relative differences between SMV1 and SMV2 simulations after 1 month CO -0.55 ÷ 0 % 6/2/2003

  11. SMVGEAR II IN GEOS-CHEM: EVALUATION Relative differences between SMV1 and SMV2 simulations after 1 month OH 0 ÷ 10 % 6/2/2003

  12. IF ( LEVEL < TROPOPAUSE ) THEN STANDARD TROPOSPHERIC CHEMISTRY MECHANISM 80 species, 288 kinetic reactions, 51 photolysis, 5 heterogeneous reactions ELSE NEW STRATOSPHERIC CHEMISTRY MECHANISM 40 species, 120 kinetic reactions, 30 photolysis, 6 heterogeneous reactions TROPOSPHERIC-STRATOSPHERIC CHEMISTRY SIMULATION BASIC IDEA OF THE SIMULATION 6/2/2003

  13. TROPOSPHERIC-STRATOSPHERIC CHEMISTRY SIMULATION MAIN FEATURES OF THE MODEL • It is implemented on: • Version 5.02 (fvDAS compatibility, pressure fixer) • GEOS-3 met-fields with 48 s-levels • NOx-Ox-Hydrocarbons simulation (NSCRX=3) • Uses SMVGEAR II chemistry solver • 6 new tracers for the stratosphere: ClOx, BrOx, HCl, HBr, ClONO2, BrONO2 (total of 30 tracers) • Revised Ox = O3+NO2+2NO3+O+O(1D)to make it suitable for the stratosphere • Photorates: FAST-J in the troposphere and SLOW-J in the stratosphere 6/2/2003

  14. TROPOSPHERIC-STRATOSPHERIC CHEMISTRY SIMULATION: EVALUATION Relative differences between STD and T-S simulations Ox 0 ÷ 60 % 6/2/2003

  15. TROPOSPHERIC-STRATOSPHERIC CHEMISTRY SIMULATION: EVALUATION Zonal mean of Ox in January 6/2/2003

  16. CONCLUSIONS AND DEVELOPMENT NEEDS • New capabilities have been developed to improve stratospheric chemistry simulation into GEOS-CHEM model: • Full stratospheric chemistry model • Tropospheric-stratospheric chemistry model to be improved • The new simulations require deep changes to the code • Changes imply adaptation of other parts of the code (diagnostics, other simulation types…) • The new code is not yet implemented for parallel computing 6/2/2003

  17. POSSIBLE APPLICATIONS • STE and stratospheric influence studies • Comparison of GEOS and fvDAS data (cross-tropopause fluxes) • Satellite data retrieval (better a-priori for the stratosphere) • Halogen chemistry • Chemistry-radiation feedback (compute J-values using calculated O3) 6/2/2003

  18. END THANKS FOR YOUR ATTENTION!  6/2/2003

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