Photochemical Modeling in California with Two Chemical Mechanisms: Model Intercomparison and Response to Emission Reductions

Figures & data

Table 1. Key rate constant or photolysis rate changes relative to SAPRC99^a

	Rate Constant or Photolysis Rate^b
Reaction^c	SAPRC07	SAPRC99	Change (%)
NO2 + HV = NO + O3P	7.23 × 10^−1	6.69 × 10^−1	8
O3P + NO = NO2	1.64 × 10^−12	2.45 × 10^−12	−33
O3P + NO2 = NO + O2	1.03 × 10^−11	9.70 × 10^−12	6
O3P + NO2 = NO3	3.24 × 10^−12	1.79 × 10^−12	81
O3 + NO = NO2 + O2	2.02 × 10^−14	1.87 × 10^−14	8
NO2 + NO3 = N2O5	1.24 × 10^−12	1.53 × 10^−12	−19
N2O5 = NO2 + NO3	5.69 × 10^−2	6.74 × 10^−2	−16
N2O5 + H2O + H2O = #2 HNO3 + H2O	1.80 × 10^−39
NO3 + HV = NO + O2	1.91 × 10^0	1.59 × 10^0	20
O1D + H2O = #2 OH	1.99 × 10^−10	2.20 × 10^−10	−10
O1D + M = O3P + M	3.28 × 10^−11	2.87 × 10^−11	14
HONO + HV = OH + NO	1.14 × 10^−1	1.27 × 10^−1	−10
HONO + HV = HO2 + NO2	—	1.60 × 10^−2
OH + HONO = H2O + NO2	5.95 × 10^−12	6.42 × 10^−12	−7
OH + NO2 = HNO3	1.05 × 10^−11	8.81 × 10^−12	19
OH + CO = HO2 + CO2	2.28 × 10^−13	2.08 × 10^−13	10
OH + O3 = HO2 + O2	7.41 × 10^−14	6.78 × 10^−14	9
HO2 + NO = OH + NO2	8.85 × 10^−12	8.36 × 10^−12	6
HO2 + NO2 = HNO4	1.12 × 10^−12	1.36 × 10^−12	−18
HO2 + O3 = OH + #2 O2	1.69 × 10^−15	1.89 × 10^−15	−11
HO2H + OH = HO2 + H2O	1.80 × 10^−12	1.70 × 10^−12	6
MeO2 + HO2 = COOH + O2	4.65 × 10^−12	5.12 × 10^−12	−9
MeO2 + HO2 = HCHO + O2 + H2O	4.50 × 10^−13
MeO2 + MeO2 = MeOH + HCHO + O2	2.16 × 10^−13	2.61 × 10^−13	−17
MeO2 + MeO2 = #2 {HCHO + HO2}	1.31 × 10^−13	1.08 × 10^−13	21
Peroxy + HO2 = products	7.63 × 10^−12	1.45 × 10^−11	−47
MeCO3 + NO2 = PAN	9.37 × 10^−12	1.04 × 10^−11	−10
PAN = MeCO3 + NO2	6.27 × 10^−4	7.04 × 10^−4	−11
PAN + HV = products	6.12 × 10^−5
MeCO3 + NO = MeO2 + CO2 + NO2	1.97 × 10^−11	2.12 × 10^−11	−7
MeCO3 + NO3 = products	2.30 × 10^−12	4.00 × 10^−12	−43
MeCO3 + MeO2 = products	1.06 × 10^−11	9.53 × 10^−12	11
MeCO3 + peroxy = products	1.56 × 10^−11	7.50 × 10^−12	108
PAN2 = RCO3 + NO2	5.48 × 10^−4	5.90 × 10^−4	−7
RCO3 + NO = products	2.08 × 10^−11	2.78 × 10^−11	−25
BZO + HO2 = CRES	7.63 × 10^−12	1.45 × 10^−11	−47
HCHO + HV = #2 HO2 + CO	2.76 × 10^−3	2.32 × 10^−3	19
HCHO + OH = HO2 + CO + H2O	8.47 × 10^−12	9.19 × 10^−12	−8
CCHO + OH = MeCO3 + H2O	1.49 × 10^−11	1.57 × 10^−11	−6
RCHO + NO3 = HNO3 + RCO3	6.74 × 10^−15	3.82 × 10^−15	76
Acetylene + OH = products	7.56 × 10^−13
Acetylene + O3 = products	1.16 × 10^−20
Benzene + OH = products	1.22 × 10^−12
Notes: ^aFrom Carter.18 ^bRate constants are for temperatures of 300 K and are in units of molecule, cm3 sec^−1. ^cNO = nitric oxide, O3P = ground state oxygen atmos, O2 = oxygen, NO3 = nitrate radical, N2O5 = nitrogen pentoxide, O1D = excited oxygen atoms, HONO = nitrous acid, M = air, H2O = water, HNO4 = peroxynitric acid, HO2H = hydrogen peroxide, MeO2 = methyl peroxy radicals, MeOH = methanol, MeCO3 = acetyl peroxy radicals, PAN2 = PPN and other higher alkyl PAN analogues, RCO3 = peroxy propionyl and higher peroxy acyl radicals, BZO = phenoxy radicals, CRES = phenols and cresols, CCHO = acetaldehyde, RCHO = lumped C3+ aldehydes.

Figure 1. (a) Difference in mean daily maximum 8-hr O₃ concentration for predictions with SAPRC99 and SAPRC07C, (b) mean daily 8-hr maximum O₃ concentration for predictions with SAPRC07C. Comparison sites are indicated by markers or numbers. Numbers (1–6) correspond to sites (left–right) in Figures 2 and 3: 1 = FLN, 2 = LIVR, 3 = PLR, 4 = ARV, 5 = RUBI, and 6 = ALPN (see Table 2 for site descriptions).

Figure 2. Hourly concentration predictions for simulations with SAPRC07C compared with those for SAPRC99. Columns (left–right) correspond to numbered sites (1–6) in Figure 1.

Figure 3. Mean diurnal concentration profiles for simulations with SAPRC07C and SAPRC99. Columns (left–right) correspond to numbered sites (1–6) in Figure 1. Hour 0 corresponds to 12:00 A.M. PST.

Table 2. Site locations and averaged VOC/NO_x (ppbC/ppb) ratios for daytime hours from 10:00 a.m. to 5:00 p.m. (PST)

							VOC/NOx (ppbC/ppb)
Site	Address	Air Basin	Latitude	Longitude	SLE (m)	Category	SAPRC99	SAPRC07C
LANM	1630 North Main Street, Los Angeles	South Coast	34.07	−118.23	87	Urban	3.39	3.46
SUN	Sunol	San Francisco Bay Area	37.59	−121.88	140	Rural	3.53	3.59
AZSA	803 North Loren Avenue, Azusa	South Coast	34.14	−117.92	183	Urban	3.81	3.93
BGS	1128 Golden State Highway, Bakersfield	San Joaquin Valley	35.39	−119.01	151	Urban	4.26	4.34
ULDS	1350 San Bernardino Road, Upland	South Coast	34.10	−117.63	369	Urban	4.31	4.48
MRM	2334 M Street, Merced	San Joaquin Valley	37.31	−120.48	53	Suburban	5.10	5.20
SIM	5400 Cochran Street, Simi Valley	South Central Coast	34.28	−118.68	310	Urban	5.25	5.42
SJO	13030 Murphy Avenue, San Martin	San Francisco Bay Area	37.08	−121.60	87	Urban	5.34	5.50
NAT	3801 Airport Road, Sacramento	Sacramento Valley	38.64	−121.51	5	Urban	5.44	5.48
FSF	3425 North First Street, Fresno	San Joaquin Valley	36.78	−119.77	96	Urban	5.61	5.69
GLA	26 Castilian Drive B-23, Goleta	South Central Coast	34.43	−119.86	30	Urban	6.21	6.25
LIVR	793 Rincon Avenue, Livermore	San Francisco Bay Area	37.68	−121.78	145	Rural	6.67	6.90
RUBI	5888 Mission Boulevard, Rubidoux	South Coast	34.00	−117.42	250	Urban	6.89	7.30
GNBY	Granite Bay	Sacramento Valley	38.74	−121.20	146	Suburban	7.00	7.05
ALPN	2300 Victoria Drive, Alpine	San Diego	32.84	−116.77	603	Urban	8.46	8.89
BANN	200 South Hathaway Street, Banning	South Coast	33.92	−116.86	473	Urban	8.73	9.57
RDS	Johnson Farm, Edison	San Joaquin Valley	35.35	−118.85	128	Urban	9.22	9.39
PGV	7310 Pacific Avenue, Pleasant Grove	Sacramento Valley	38.77	−121.52	10	Rural	10.06	10.54
FLN	50 Natoma Street, Folsom	Sacramento Valley	38.68	−121.16	98	Urban	10.44	10.65
RIVY	695 Young Street, San Jacinto	South Coast	33.80	−116.97	459	Suburban	11.02	12.36
PLR	9240 South Riverbend Avenue, Palier	San Joaquin Valley	36.60	−119.50	78	Rural	11.50	11.90
KCW	Omaha Avenue, Kettleman	San Joaquin Valley	36.10	−119.95	69	Rural	17.75	20.11
ARV	20401 Bear Mountain Boulevard, Arvin	San Joaquin Valley	35.21	−118.78	145	Suburban	22.30	22.71
FEDL	8555 South Valentine, Fresno	San Joaquin Valley	36.61	−119.86	76	Rural	28.11	30.63
ANGI	36078 Fourth Avenue, Corcoran	San Joaquin Valley	35.95	−119.53	60	Rural	31.81	35.90
Notes: SLE = sea level elevation. All of the sites listed are ground sites.

Table 3. Summary statistics for O₃ predictions based on SAPRC07C compared with those based on SAPRC99 at 25 sites in California

	Mean Daily Maximum 8-hr O3 (ppb)		Comparison over All Hours
Site ^a	SAPRC99	SAPRC07C	R ^b	NMB ^c	NMD ^d	RMSD ^e
BANN	101.3	94.8	0.99	−6.7	6.8	6.18
RIVY	100.7	94.5	1	−7.6	7.6	5.62
ARV	95.0	85.8	0.99	−6.9	7	6.42
RUBI	83.3	75.6	1	−10.2	10.2	5.51
RDS	82.7	76.3	0.99	−6.9	7	5.01
ALPN	82.0	76.4	0.99	−4.7	4.7	3.79
FLN	79.6	76.2	1	−1.9	2.8	2.4
FSF	78.6	73.6	1	−6.3	6.3	4.01
PLR	78.3	73.7	1	−6	6	3.65
SIM	76.5	71.7	1	−4.3	4.5	3.33
FEDL	74.6	71.4	1	−4.1	4.2	2.68
SJO	71.4	67.8	0.99	−3.2	4.5	3.08
GNBY	71.2	68.4	1	−1.6	2.8	2.11
BGS	69.9	65.1	1	−7.9	7.9	3.53
MRM	69.3	63.8	1	−5.7	6.3	3.71
GLA	68.7	65.7	0.99	−2.6	3.2	2.23
ANGI	67.0	63.8	1	−3.8	3.9	2.41
KCW	66.0	62.9	0.99	−3.3	3.5	2.31
LIVR	65.3	62.1	1	−2.1	4	2.48
ULDS	64.9	58.5	1	−12.1	12.1	4.78
NAT	60.0	58.3	1	−1	3.1	1.47
SUN	59.6	55.6	1	−2.6	4.7	2.65
PGV	55.9	54.8	1	−0.9	2.2	1.22
AZSA	55.0	49.1	0.99	−8.2	8.3	3.94
LANM	40.3	36.5	1	−9.7	9.8	2.55
Notes:
^aSee Table 2 and Figure 1 for site locations; ^bPearson correlation coefficient for predictions with SAPRC07C and SAPRC99; ^c ; ^dNormalized mean difference ^eRoot mean square difference (ppb) .

Figure 4. (a) Scatterplots of O₃ vs. ln(VOC/NO_x) for 180 sites for SAPRC99 and SAPRC07C. (b) Scatterplots of normalized O₃ difference 100% × (O3,SAPRC07C - O3,SAPRC99)/O3,SAPRC99 vs. ln(VOC/NO_x). (c) Scatterplot of OPE vs. ln(VOC/NO_x). (d) Scatterplot of normalized OPE difference 100% × (OPESAPRC07C - OPESAPRC99)/OPESAPRC99 vs. ln(VOC/NO_x). Note: O₃ and VOC/NO_x are averaged over daytime hours from 10:00 a.m. to 5:00 p.m. for each site. VOC/NO_x values are from the SAPRC99 simulation. OPE is the slope of O₃ vs. NO_z regression for the hours from 10:00 a.m. to 5:00 p.m. at each site. Only the sites with O₃ vs. NO_z R [H11022] 0.7 are considered for panels c and d.

Figure 5. IC in a uniform O₃ concentration of 75 ppb as a result of (a) 20% reduction in NO_x and (b) 20% reduction in VOC emissions for the SAPRC99 mechanism (see eq 1 for the definition of IC).

Table 4. Ratio of simulated average daily maximum 8-hr O₃ between the 20% emission reduction and base case simulations for the SAPRC99 and SAPRC07C mechanisms

		O3 Response to 20% NOx Reduction		O3 Response to 20% NMVOC Reduction
Case	Site	SAPRC99	SARPC07C	SAPRC99	SARPC07C
1	ANGI	0.94	0.97	0.97	0.95
	FEDL	0.93	0.97	0.97	0.96
	FLN	0.93	1.00	0.97	0.96
	GNBY	0.95	1.00	0.97	0.96
	KCW	0.94	0.98	0.97	0.96
	NAT	0.95	0.99	0.98	0.97
	PGV	0.93	0.97	0.99	0.97
	PLR	0.94	1.00	0.96	0.93
2	ALPN	1.00	1.05	0.93	0.92
	AZSA	1.29	1.34	0.84	0.82
	BANN	1.06	1.11	0.88	0.87
	LANM	1.36	1.30	0.88	0.87
	LIVR	1.01	1.05	0.96	0.95
	MRM	1.01	1.07	0.94	0.91
	RIVY	1.04	1.07	0.90	0.89
	RUBI	1.18	1.23	0.85	0.83
	SJO	1.02	1.06	0.95	0.94
	SUN	1.05	1.11	0.94	0.94
	ULDS	1.30	1.35	0.82	0.80
3	ARV	0.95	1.04	0.93	0.89
	BGS	0.97	1.02	0.95	0.92
	FSF	0.97	1.02	0.95	0.93
	GLA	0.98	1.03	0.97	0.95
	RDS	0.97	1.03	0.94	0.91
	SIM	0.97	1.06	0.94	0.93

Figure 6. Comparison of the ratios of simulated average daily maximum 8-hr O₃ between the 20% NO_x emission reduction and base case simulation for the SAPRC99 and SAPRC07C mechanisms. Case 1: SAPRC99 ratio [H11349] 1 and SAPRC07C ratio [H11349] 1; case 2: SAPRC99 ratio [H11022] 1 and SAPRC07C ratio [H11022] 1; case 3: SAPRC99 ratio [H11021] 1 and SAPRC07C ratio [H11022] 1.

Figure 7. Difference in the IC in O₃ between the SAPRC99 and SAPRC07C mechanisms in response to (a) 20% NO_x or (b) 20% VOC emissions reductions on the basis of a uniform O₃ concentration of 75 ppb (ICSAPRC99 - ICSAPRC07) (see eq 1 for the definition of IC).

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