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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, Bo Wang Tiegang Cao, Zion Wang, Mohammad Omary, Youjun Qin University of California – Riverside, CE-CERT . Models-3 CMAS Workshop, Oct.27-29, 2003, RTP, NC.

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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, Bo Wang Tiegang Cao, Zion Wang, Mohammad Omary, Youjun Qin University of California – Riverside, CE-CERT Models-3 CMAS Workshop, Oct.27-29, 2003, RTP, NC

  2. Current regulatory version of CB4 (Gery et al. 1989) has modifications but is outdated. New updated CB4,CB4-2002, released by Jeffries et al. in late 2002 Contains 100 principle reactions and same CB4 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. Four versions of “swappable” olefin chemistry. Recommended replacement version is used. CB4 mechanism update . ! KINETICS DATA SOURCES: !'97 NASA DOCUMENT: !"CHEMICAL KINETICS AND PHOTOCHEMICAL DATA FOR USE IN ! STRATOSPHERIC MODELING," DEMORE, ET AL., JANUARY 15, ! 1997, JPL PUBLICATION 97-4. ! '97 IUPAC DOCUMENT: ! "EVALUATED KINETIC AND PHOTOCHEMICAL, AND! HETEROGENEOUS DATA FOR ATMOSPHERIC CHEMISTRY:! SUPPLEMENT V," ATKINSON, ET AL., ! J. PHYS. CHEM. REF DATA, VOL 26, NO 3 AND NO 6, 1997. . . <IB5F> NO3 + NO2 = N2O5 # 2.00E-30^-4.4&1.40E-12^-0.7; <IB5R> N2O5 = NO3 + NO2 # 3.0E-27@-10991.0*E<IB5F> ; ! IB5F: NASA00, T2, T3; IB5R KEQ=3.0E-27@-10991/T) . . !<IB6> AND<IB7> HOMOGENEOUS HYDROLYSIS ONLY; WAHNER ET AL, GRL, 25(12):2169, 1998 <IB6> N2O5 + H2O = 2.0*HNO3 # 2.5E-22; <IB7> N2O5 + H2O + H2O = 2.0*HNO3 + H2O # 1.8E-39;

  3. Major revisions in CB4 mechanism update • Updated photolysis rates; applying 12 photolysis rates, an expansion from current 7 (6 original) photolysis rates used in CB4.

  4. Major revisions in CB4 mechanism update (cont’d) • Additional homogeneous N2O5 hydrolysis reaction are added: • N2O5 + H2O + H2O  2HNO3 + H2O (Wahner et al. GRL, 1998)

  5. Major revisions in CB4 mechanism update (cont’d) Comparison of four recommendations for the reaction rate of OH + NO2 (at 300K)* • Reaction rate of OH + NO2  HNO3, recommended by Troe(2001) is used. (12% lower than current CMAQ rate) 138% 112% 100% 92% CMAQ IUPAC Troe NASA J. TROE, Int. J. Chem. Kin. 33, 2001 * from Jeffries et al. (2002)

  6. Other major revisions made in CB4_2002 from old CB4 Reaction rates and product distributions are updated to reflect the most recent research findings; changes also include: New kinetic rate expression for HONO formation, and the use of new cross-sections for the HONO dissociations. Updated PAN formation and decay kinetics. Revised rates and product yields for Olefin chemistry: OLE/ETH + O3 (NO3, O3P)  to be consistent with current literature. However, aromatic chemistry left unchanged. Major revisions in CB4 mechanism update (cont’d)

  7. Additional reactions added to CB4_2002 “… some reactions are in the mechanism just for those conditions that are quite different than the ones in the outdoor chamber simulation…” Jeffries H.

  8. CB4_02_AE3_AQ CB4_2002 in “Morpho” language format, needs to be converted to CMAQ format Followed the changes made in cb4 for new version of CMAQ New deposition velocity surrogates New cloud scavenging surrogates 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). With and without gaseous reaction rate constants for N2O5 hydrolysis (Sensitivity run : CB4_02 _zeroN2O5 ) Process new photolysis rate tables (JTables) Implementation of CB4_2002 with aerosol and aqueous extensions in CMAQ v.4.3

  9. CMAQ v.4.3; smvgear option CB4_02_ae3_aq with gaseous N2O5 reactions (CB4_02) CB4_02_ae3_aq zero out gaseous N2O5 reactions (CB4_02_zeroN2O5) WRAP 1996 January and July episodes Model difference: CB4 vs. CB4_02 vs. CB4_02_zeroN2O5 Daily average spatial plots and domain daily average time series plots for O3, HNO3, PAN, N2O5, ANO3, ASO4, and SOA Comparisons against ambient data: Normalized Mean Bias (NMB%) and Mean Fractionalized Bias (MFB%) AQS (AIRS): July hourly O3 IMPROVE: daily NO3, SO4, OC CASTNet: July daily HNO3, NO3, NH4, SO2, SO4 Evaluation of CB4_2002

  10. O3, CB4 vs. CB4_02 vs. CB4_02_zeroN2O5 January • Jan. daily average concentration comparison. • Hourly variations as high as 40 ppb. • CB4_02_zeroN2O5 produced highest avg. O3 concentration. 1st Layer Domain Daily Avg. CB4 __ CB4-02 __ CB4-02-zeroN2O5 __

  11. O3, CB4 vs. CB4_02 vs. CB4_02_zeroN2O5 July • July daily average concentration comparison. • Higher O3 in urban areas. Hourly variations more than 100 ppb in some areas. • CB4 produces highest average O3, while CB4_02 least. 1st Layer Domain Daily Avg. CB4 __ CB4-02 __ CB4-02-zeroN2O5 __

  12. HNO3, CB4 vs. CB4_02 vs. CB4_02_zeroN2O5 January • Jan. daily average concentration comparison. • CB4_02 produced more than 1 ppb HNO3 than CB4. • CB4 and CB4_02_zeroN2O5 produces similar HNO3. 1st Layer Domain Daily Avg. CB4 __ CB4-02 __ CB4-02-zeroN2O5 __

  13. HNO3, CB4 vs. CB4_02 vs. CB4_02_zeroN2O5 July • July daily average concentration comparison. • CB4_02 higher in urban areas. Hourly variations as high as 10 ppb. • CB4_02 produces highest average HNO3, whereas CB4_02_zeroN2O5 least. 1st Layer Domain Daily Avg. CB4 __ CB4-02 __ CB4-02-zeroN2O5 __

  14. PAN, CB4 vs. CB4_02 vs. CB4_02_zeroN2O5 January 1st Layer Domain Daily Avg. CB4 __ CB4-02 __ CB4-02-zeroN2O5 __

  15. PAN, CB4 vs. CB4_02 vs. CB4_02_zeroN2O5 July 1st Layer Domain Daily Avg. CB4 __ CB4-02 __ CB4-02-zeroN2O5 __

  16. N2O5, CB4 vs. CB4_02 vs. CB4_02_zeroN2O5 January 1st Layer Domain Daily Avg. CB4 __ CB4-02 __ CB4-02-zeroN2O5 __

  17. N2O5, CB4 vs. CB4_02 vs. CB4_02_zeroN2O5 July 1st Layer Domain Daily Avg. CB4 __ CB4-02 __ CB4-02-zeroN2O5 __

  18. ANO3, CB4 vs. CB4_02 vs. CB4_02_zeroN2O5 January • Jan. daily average concentration comparison. • CB4_02 produced as high as 5 ug/m3 of NO3 than CB4. • CB4 and CB4_02_zeroN2O5 produces similar NO3. 1st Layer Domain Daily Avg. CB4 __ CB4-02 __ CB4-02-zeroN2O5 __

  19. ANO3, CB4 vs. CB4_02 vs. CB4_02_zeroN2O5 July • July daily average concentration comparison. • CB4_02 produced more than 2 ug/m3 of NO3 than CB4 in some areas. • CB4_02 produced highest NO3 average; CB4 produced a little higher than CB4_02_zeroN2O5. 1st Layer Domain Daily Avg. CB4 __ CB4-02 __ CB4-02-zeroN2O5 __

  20. ASO4, CB4 vs. CB4_02 vs. CB4_02_zeroN2O5 January • Jan. daily average concentration comparison. • CB4 produced less than 0.5 ug/m3 SO4 than CB4_02. • CB4 produced slightly lower SO4 than CB4_02 and CB4_02_zeroN2O5. 1st Layer Domain Daily Avg. CB4 __ CB4-02 __ CB4-02-zeroN2O5 __

  21. ASO4, CB4 vs. CB4_02 vs. CB4_02_zeroN2O5 July • July daily average concentration comparison. • As high as 1 ug/m3 of difference between CB4 and CB4_02. • Overall, CB4_02_zeroN2O5 produced similar SO4 avg. to CB4_02. 1st Layer Domain Daily Avg. CB4 __ CB4-02 __ CB4-02-zeroN2O5 __

  22. SOA, CB4 vs. CB4_02 vs. CB4_02_zeroN2O5 January • Jan. daily average concentration comparison. • No significance difference. • All three produced similar avg. conc. of SOA. 1st Layer Domain Daily Avg. CB4 __ CB4-02 __ CB4-02-zeroN2O5 __

  23. SOA, CB4 vs. CB4_02 vs. CB4_02_zeroN2O5 July • July daily average concentration comparison. • CB4 produced slightly higher than CB4_02. • CB4_02_zeroN2O5 produced similar SOA avg. to CB4_02. 1st Layer Domain Daily Avg. CB4 __ CB4-02 __ CB4-02-zeroN2O5 __

  24. AQS, CB4 vs. CB4_02 vs. CB4_02_zeroN2O5

  25. IMPROVE, January, Normalized Mean Bias

  26. IMPROVE, July, Normalized Mean Bias

  27. CASTNet, July , CB4 vs. CB4_02 vs. CB4_02_zeroN2O5

  28. Major difference found for O3, HNO3, ANO3 Higher O3 concentration in urban area but lower in rural area. (probable cause: combined effect of OH+NO2 rate, less long range transport of PAN formation) Comparisons with ambient data: Improvements are mixed and relatively small Should gaseous N2O5 reactions be taken out? Would it sensitive to emission changes (control runs)? Next steps… Process analysis to identify key contributors to the changes Implement EBI/MEBI (Modified Euler Backward Iterative) solver for CB4_02 Implement paraffinsecondary organic aerosol into CB4_02. Improve aromatic chemistry mechanism. Summary of CB4_2002 modeling results

  29. Bottom line… In spite of relatively small changes comparing the ambient data, CB4_2002 has better science and should be included in future CMAQ release. Summary of CB4_2002 modeling results

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