An extended approach to calculate the ozone relative response factors used in the attainment demonstration for the National Ambient Air Quality Standards

Figures & data

Figure 1. The ozone monitoring stations in the San Joaquin Valley (SJV) region of California. SJVAPCD stands for the San Joaquin Valley Air Pollution Control District. The outer box of the left panel is the California statewide 12-km modeling domain. The gray shaded and black line contours denote the gradients in topography (km), while the thick black lines show the boundaries of the SJV subregions used in model performance analysis (see Supplemental Materials for further details on model performance). Simulations for this study were conducted using the inner modeling domain at 4 km resolution that covers the entire Central Valley of California. The insert on the right shows a zoomed-in view of the site locations that were used for model performance evaluation. Table 1 lists only a subset of these sites (the 10 highest 1-hr and 8-hr O₃ DVs for the year 2007).

Figure 2. An illustration of the band-RRF procedure for the Edison monitoring site. The top left panel shows the time series of observed (black circles) and simulated (black line) daily maximum 1-hr O₃ for the simulation period (May–September 2007). The top right panel shows the scatter plot of binned band-RRF for 1-hr O₃ from 60 to 120 ppb (in 5-ppb increments) vs. the number of bands. The bottom left panel shows the time series of observed (black circles) and simulated (black line) daily maximum 8-hr O₃ for the simulation period (May–September 2007). The bottom right panel shows the scatter plot of binned band-RRF from 60 to 100 ppb (in 5-ppb increments) for 8-hr O₃ vs. the number of bands. S.RRF and B.RRF denote single- and band-RRFs, respectively.

Table 1. The 2007 and 2019 O₃ DVs for representative monitoring sites in the San Joaquin Valley of California; listed here are the top 10 2007 DV sites for both 1-hr and 8-hr O₃

1-hr O3				8-hr O3
Monitoring station	DV (ppb) ambient (2005–2007)^a	DV (ppb) single (2007–2019)^b	DV (ppb) band (2007–2019)^b	Monitoring station	DV (ppb) ambient (2005–2007)^a	DV (ppb) single (2007–2019)^b	DV (ppb) band (2007–2019)^b
Edison	135	111.9	108.1	Arvin	107	88.8	85.5
Arvin	131	105.5	103.1	Sequoia and King Canyon	103	86.2	84.7
Fresno 1st street	130	105.3	98.1	Edison	99	83.2	81.0
Clovis	125	100.9	96.1	Fresno 1st street	98	81.6	78.3
Fresno Sierra Skypark	124	100.9	92.1	Bakersfield	97	81.3	79.0
Parlier	121	95.4	92.6	Fresno Sierra Skypark	95	79.1	76.1
Sequoia and King Canyon	118	98.7	94.8	Sequoia National Park	95	81.0	81.6
Bakersfield	117	96.8	94.5	Visalia N. Church Street	95	80.4	78.7
Sequoia National Park	113	94.9	92.1	Clovis	93	77.1	75.0
Visalia N. Church Street	112	88.6	87.8	Parlier	93	76.7	74.3
Oildale	112	93.3	92.0	Oildale	91	74.5	73.1

Notes: ^aThe three year period included in the ambient design value calculations.

^bThe base year 2007 and future year 2019 used for air quality model simulations used in this study.

Figure 3. The total PM_2.5 daily concentration ratios (2019/2007) at Modesto, Fresno, Visalia, and Bakersfield monitoring sites in the SJV region. The solid line represents the power form of the regression. (See Chen et al. [2014] for further details on the simulated PM_2.5 concentrations.)

Chen, J., J. Lu, J. Avise, J. DaMassa, M.J. Kleeman, and A.P. Kaduwela. 2014. Seasonal modeling of PM2.5 in California’s San Joaquin Valley. Atmos. Environ. 92:182–90. doi:10.1016/j.atmosenv.2014.04.030

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