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Model & Chemistry Intercomparison CMAQ with CB4, CB4-2002, SAPRC99

Model & Chemistry Intercomparison CMAQ with CB4, CB4-2002, SAPRC99.

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Model & Chemistry Intercomparison CMAQ with CB4, CB4-2002, SAPRC99

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  1. Model & Chemistry IntercomparisonCMAQ with CB4, CB4-2002, SAPRC99 Ralph Morris, Steven Lau, Bongyoung KooENVIRON International CorporationGail Tonnesen, Chao-Jung Chien, Zion Wang, Bo Wang, Tiegang Cao University of California at RiversideT.W. Tesche, Dennis McNally and Greg StellaAlpine Geophysics RPO Meeting, Denver, CO, May 25, 2004

  2. Chemistry Versions • CB4 developed in 1989, has patches but no chemical kinetics updates. • CB4-2002 (Jeffries et al.) major changes include updated HNO3, PAN, alkenes, and photo-rates. • SAPRC99 includes more detailed organic chemistry, explicit organic peroxy radicals. Provides better representation of peroxides for low NOx and more complete organic intermediates. • CB5 – not yet evaluated.

  3. N2O5 Hydrolysis • Potentially important path for converting NOx to inert HNO3: O3+NO  NO2 O3+NO2  NO3 NO2+NO3  N2O5 N2O5+H2O  2 HNO3 • Potentially important sink for oxidants.

  4. N2O5 Hydrolysis • G1: Gas Phase: N2O5+H2O  2 HNO3 • G2: Gas phase: N2O5 + H2O + H2O  2 HNO3 • H1: Heterogeneous: N2O5 + H2O + M  2 HNO3, various parameterizations used for reaction probability (). • Kinetics based limited, mostly data from Julich chamber experiments.

  5. Chemistry N2O5 Hydrolysis • Original CB4 has G1, artificially increased. • CMAQ version CB4 does not include G1. • CB4-2002 has G1 and G2. • SAPRC99 has G1. • CMAQ includes H1, with 0.01 <  < 0.1

  6. Organic Aerosol Formation • Primary anthropogenic organic aerosols. • Secondary Organic aerosols (SOA) • Includes anthropogenics and biogenics. • CMAQ has 10 SOA precursors • SAPRC99 includes paraffin SOA, CB4 does not.

  7. Mechanism intercomparison for Jan02 episode

  8. US Vistas States Species Network CB4 CB4_2002 SAPRC99 CB4 CB4_2002 SAPRC99 FE(%) FB (%) FE(%) FB (%) FE(%) FB (%) FE(%) FB (%) FE(%) FB (%) FE(%) FB (%) IMPROVE 60.16 20.86 60.97 27.61 61.81 -13.03 54.78 3.46 56.63 14.32 52.32 -20.24 CASTNET 39.03 30.39 46.89 41.57 33.05 -5.62 40.55 38.93 51.73 51.71 24.88 7.63 NH4 SEARCH 45.04 17.12 50.91 27.09 36.61 -3.93 Same as US SEARCH_H 81.96 40.53 87.98 49.75 72.07 20.86 STN 48.07 4.07 50.18 15.04 54.26 -25.06 59.68 5.74 63.30 15.06 53.87 -14.24 IMPROVE 77.21 59.23 76.93 59.36 69.17 44.53 43.10 7.85 43.20 9.56 38.67 -0.34 OC Same as US SEARCH 49.89 3.92 49.44 5.24 49.33 -5.02 STN 55.31 6.02 55.22 6.80 56.35 4.18 62.38 -44.57 61.48 -43.43 65.98 -49.90 IMPROVE 66.00 36.96 65.99 36.95 66.01 36.92 53.24 17.12 53.22 17.11 53.27 17.15 EC Same as US SEARCH 58.91 1.60 58.91 1.62 58.92 1.53 STN 87.68 69.96 87.67 69.95 87.67 69.94 68.28 21.30 68.27 21.30 68.26 21.28 Same as US SEARCH_H 86.71 17.39 86.80 18.25 83.49 11.60 TCM STN 57.58 21.14 57.65 21.70 58.41 19.63 54.62 -31.79 54.10 -30.92 56.91 -35.87 CM IMPROVE 84.69 -8.34 84.69 -8.34 90.39 -34.97 62.98 -1.77 62.98 -1.77 70.66 -38.11 IMPROVE 165.78 164.40 165.78 164.41 165.75 164.37 172.88 172.88 172.89 172.89 172.88 172.88 SOIL Same as US SEARCH 180.24 180.24 180.25 180.25 180.21 180.21 STN 170.04 168.76 170.04 168.76 170.02 168.73 159.70 149.91 159.70 149.93 159.70 149.89 IMPROVE 87.74 80.55 89.40 82.70 78.73 66.38 59.96 43.85 64.60 49.01 50.34 29.40 SEARCH 47.56 24.57 49.77 28.38 42.35 13.38 PM25 Same as US SEARCH_H 81.80 33.54 83.76 36.95 76.33 24.63 STN 51.00 30.93 53.61 34.97 47.76 21.09 50.96 5.92 53.86 9.86 48.32 -4.29 PM10 IMPROVE 73.93 53.39 74.99 55.24 66.98 36.23 52.49 31.87 56.33 36.52 42.67 13.41

  9. Summary • CB4 & CB4-2002 are similar. • Both CB4 and SAPRC under predicted winter O3 • SAPRC had larger negative bias for O3 • Winter NO3 performance: • CB4 had positive bias • SAPRC had large negative bias. • SAPRC99 had lower SOA than CB4: • SAPRC99 better in winter, negative bias summer. • CB4 performance appears to be better than SAPRC. • More diagnostic evaluation is needed.

  10. Recommendations • SAPRC99 computational cost is 2x CB4. • Compromise between chemistry and grid size. • Use 36-12 km grid with CB4 chemistry • Need to compare model response to emissions reductions.

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