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CMAQ Model Performance Evaluation with the updated CB4-2002

CMAQ Model Performance Evaluation with the updated CB4-2002. Chao-Jung Chien, Gail Tonnesen, Zion Wang, Mohammad Omary, Bo Wang, Youjun Qin, Tiegang Cao. October 8, WRAP Modeling Forum Meeting, Riverside, CA. Current regulatory version of CB4 (CB4_89, from Gery et al. 1989) is outdated.

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CMAQ Model Performance Evaluation with the updated CB4-2002

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  1. CMAQ Model Performance Evaluation with the updated CB4-2002 Chao-Jung Chien, Gail Tonnesen, Zion Wang, Mohammad Omary, Bo Wang, Youjun Qin, Tiegang Cao October 8, WRAP Modeling Forum Meeting, Riverside, CA

  2. Current regulatory version of CB4 (CB4_89, from Gery et al. 1989) is outdated. New updated CB4,CB4_2002, released by Jeffries et al. in 2002 Contains 100 principle reactions and 39 model species (excluding secondary organic aerosol precursor species and aqueous species) Fully re-evaluated with smog chamber data Better documentation; the old CB4 in which many of the changes since 1989 have not been well documented. in “Morpho” language format, needs to be converted to CMAQ format CB4 mechanism update

  3. Major revisions made in CB4_2002 from old CB4 Updated photolysis rates; applying 12 photolysis rates, an expansion from 6 photolysis rates used in old CB4. Reaction rates and product distributions are updated to reflect the most recent research findings; the most significant changes are: Additional N2O5 hydrolysis reaction are added: N2O5 + H2O + H2O  2HNO3 + H2O New kinetic rate expression for HONO formation (1.5 times higher), and the use of new cross-sections for the HONO dissociations. A 12% lower reaction rate of OH + NO2  HNO3, recommended by NASA is used (30% lower rate recommended by IUPAC) . Updated PAN formation and decay kinetics. Revised rates and product yields for reactions of OLE + O3 (NO3, O3P)  to be consistent with current literature. Aromatic chemistry left unchanged. CB4 mechanism update (cont.)

  4. Additional reactions added to CB4_2002

  5. CB4_02_AE3_AQ Followed the changes made in cb4 for new version of CMAQ New deposition velocity surrogates New cloud scavenging surrogates Changed names of aero3/SOA NR species Eliminated advection and diffusion of fast-reacting species (e.g. OH, HO2) Modified gas-phase Monoterpene reaction rates (to be consistent with those in SAPRC mechanism): higher rate for OH rxn, lower rate for NO3 and O3 rxns. Except changes in ... Zeroing reaction rate constant for N2O5+H2O2HNO3 Implementation of CB4_2002 with aerosol and aqueous extensions in CMAQ v.4.3

  6. CMAQ v.4.3 with CB4_02_ae3_aq; smvgear option WRAP 1996 January and July episodes Area differences between CB4_02 vs. CB4 (pave plots) Comparisons against ambient data: (statistics: MFB%, NMB%) AQS (31 sites in Jan., 439 sites in July) IMPROVE, (44 sites in Jan., 49 sites in July) CASTNet (3 sites in Jan., 25 sites in July) NADP (87 sites in Jan.,103 sites in July) Evaluation of CB4_2002

  7. O3, CB4_02 vs. CB4 January (max: 45 ppb, min: -47 ppb) July (max: 150 ppb, min: -110 ppb)

  8. HNO3, CB4_02 vs. CB4 January (max: 11 ppb, min: -8 ppb) July (max: 16 ppb, min: -13 ppb)

  9. ANO3, CB4_02 vs. CB4 January (max: 25 ug/m3, min: -22 ug/m3) July (max: 54 ug/m3, min: -41 ug/m3)

  10. ASO4, CB4_02 vs. CB4 January (max: 69 ug/m3, min: -68 ug/m3) July (max: 106 ug/m3, min: -109 ug/m3)

  11. SOA, CB4_02 vs. CB4 January (max: 113 ug/m3, min: -114 ug/m3) July (max: 121 ug/m3, min: -107 ug/m3)

  12. AQS

  13. AQS, CB4_02 vs. CB4 * no amb cutoff ** with 60 ppb amb cutoff

  14. Station 04_019_0002 (located in AZ) July

  15. IMPROVE

  16. IMPROVE, January, CB4 vs. CB4_02

  17. IMPROVE, January, CB4 vs. CB4_02

  18. IMPROVE, July, CB4 vs. CB4_02

  19. IMPROVE, July, CB4 vs. CB4_02

  20. IMPROVE, January, Mean Fractionalized Bias

  21. IMPROVE, July, Mean Fractionalized Bias

  22. exclude January comparison (only 3 sites and 3 sampling period data available) CASTNet

  23. CASTNet, July , CB4 vs. CB4_02

  24. CASTNet, July , CB4 vs. CB4_02

  25. Total weekly deposition (kg/ha) for SO4, NO3, and NH4 CCTM_v43_cb4_02_smvgear.baseh.WETDEP1.1996${DATE} NADP

  26. NADP, January, CB4 vs. CB4_02

  27. NADP, July, CB4 vs. CB4_02

  28. Major difference found in both gaseous species: O3, HNO3, and aerosol species: NO3, SO4 and SOA Higher O3 concentration in urban area but lower in rural area. Comparisons with ambient data: O3 predictions better in July but worse in January No or little improvement for IMPROVE data Small improvement for CASTNet and NADP data more improvement in July than in January Next steps… Implement EBI/MEBI (Modified Euler Backward Iterative) solver for CB4_02 Implement paraffinsecondary organic aerosol into CB4_02. Sensitive to emission changes (control runs)? Improve aromatic chemistry mechanism. Summary of CB4_2002 modeling results

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