Model & Chemistry IntercomparisonCMAQ with CB4, CB4-2002, SAPRC99

Ralph Morris, Steven Lau, Bongyoung KooENVIRON International Corporation

Gail Tonnesen, Chao-Jung Chien, Zion Wang, Bo Wang, Tiegang Cao University of California at Riverside

T.W. Tesche, Dennis McNally and Greg StellaAlpine Geophysics

RPO Meeting, Denver, CO, May 25, 2004

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.

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.

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.

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

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.

FE(%) FB (%) FE(%) FB (%) FE(%) FB (%) FE(%) FB (%) FE(%) FB (%) FE(%) FB (%)

O3 AQS 73.29 -73.29 71.48 -71.48 123.80 -123.80 42.79 -42.79 41.56 -41.56 62.98 -62.98

NO2 AQS 54.69 16.20 54.83 14.19 72.27 -39.48 54.38 24.97 54.10 21.84 62.73 -18.67

AQS 100.53 61.69 100.50 61.65 100.47 60.82 88.15 46.93 88.07 46.84 87.85 46.21

CASTNET 59.27 46.88 59.14 46.67 58.08 45.22 51.05 50.13 50.82 49.89 50.03 49.04

CO AQS 83.55 -5.04 83.58 -5.09 83.57 -4.39 71.39 -22.10 71.43 -22.19 72.05 -23.79

IMPROVE_r 64.15 14.48 63.41 16.96 59.66 5.18 46.16 -27.00 42.94 -20.42 37.57 -12.92

IMPROVE_s 59.56 7.47 58.76 9.98 57.05 -1.75 46.00 -29.59 42.60 -23.00 37.09 -15.32

CASTNET 43.73 -21.18 41.35 -17.68 33.02 -16.39 38.10 -32.62 34.76 -27.59 23.16 -14.91

SEARCH 42.07 -5.19 39.75 0.46 32.51 6.36

SEARCH_H 72.78 -17.61 70.69 -11.23 64.12 -3.12

STN 46.47 -19.64 44.96 -17.48 43.07 -13.06 52.45 -31.95 50.39 -27.45 43.24 -23.22

IMPROVE 89.20 24.44 90.95 34.43 100.16 -51.16 100.28 48.86 104.64 62.36 85.27 -18.14

CASTNET 71.40 45.91 78.62 59.55 74.98 -28.47 79.70 62.50 91.53 77.22 63.31 -7.00

SEARCH 86.87 41.63 93.26 54.41 71.35 -18.53

SEARCH_H 105.75 32.98 112.40 45.14 97.63 -23.81

STN 62.93 -21.10 62.06 -3.20 104.30 -94.24 87.72 -2.60 92.01 10.76 83.93 -58.34

G_HNO3 CASTNET 79.63 -36.84 70.97 -19.20 122.31 -111.78 74.76 -36.81 65.40 -15.62 111.17 -94.79

Total_NO3 CASTNET 41.90 25.76 49.82 41.68 69.64 -59.25 40.08 37.40 54.97 54.97 45.21 -37.68

NO3

SO2

SO4

Same as US

Same as US

US Vistas StatesSpecies Network CB4 CB4 CB4_2002 SAPRC99SAPRC99CB4_2002

Mechanism intercomparison for Jan02 episode

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

SEARCH 45.04 17.12 50.91 27.09 36.61 -3.93

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

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

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

SEARCH_H 86.71 17.39 86.80 18.25 83.49 11.60

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

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

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

CB4_2002 SAPRC99

Same as US

Same as US

Species Network

US Vistas StatesCB4 CB4_2002 SAPRC99 CB4

Same as US

Same as US

Same as US

Same as US

PM25

NH4

OC

EC

SOIL

TCM

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.

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.