Air Quality Modeling Technical Support 

Document: Changes to the Renewable Fuel 

Standard Program 
 

EPA 454/R-10-001 

January 2010 

Air Quality Modeling Technical Support Document: 

Changes to the Renewable Fuel Standard Program 

U.S. Environmental Protection Agency 

Office of Air Quality Planning and Standards 

Air Quality Assessment Division 

Research Triangle Park, NC 27711 

January 2010 

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I. Introduction 

This document describes the air quality modeling performed by EPA in support of the 

final revisions to the National Renewable Fuel Standard rule (commonly known as RFS2). A 

national scale air quality modeling analysis was performed to estimate the effect of the rule on 

future year: annual and 24-hour PM2.5 concentrations, daily maximum 8-hour ozone 

concentrations, annual nitrogen and sulfur deposition levels, and select annual and seasonal air 

toxic concentrations (formaldehyde, acetaldehyde, ethanol, benzene, 1,3-butadiene, acrolein). 

To model the air quality benefits of this rule we used the Community Multiscale Air Quality 

(CMAQ)1

 model. CMAQ simulates the numerous physical and chemical processes involved in 

the formation, transport, and destruction of ozone, particulate matter and air toxics. In addition 

to the CMAQ model, the modeling platform includes the emissions, meteorology, and initial and 

boundary condition data which are inputs to this model. 

It is critical to note that a key limitation of the air quality modeling analysis is that it 

employed interim emission inventories, which were somewhat enhanced compared to what was 

described in the proposal, but due to the timing of the analysis did not include some of the later 

enhancements and corrections of the final emission inventories presented in the FRM (see 

Section 3.3 of the RIA). Most significantly, our modeling of the air quality impacts of the 

renewable fuel volumes required by RFS2 relied upon interim inventories that assumed that 

ethanol will make up 34 of the 36 billion gallon renewable fuel mandate, that approximately 20 

billion gallons of this ethanol will be in the form of E85, and that the use of E85 results in fewer 

emissions of direct PM2.5 from vehicles. The emission impacts and air quality results would be 

different if, instead of E85, more non-ethanol biofuels are used or mid-level ethanol blends are 

approved. There are additional, important limitations and uncertainties associated with the 

interim inventories that must be kept in mind when considering the results. These limitations 

and uncertainties are described in more detail in Section 3.4.1.3 of the RIA. 

II. CMAQ Model Version, Inputs and Configuration 

The 2005-based CMAQ modeling platform was used as the basis for the air quality 

modeling of the two future baselines and the RFS2 future control scenario for this final rule. 

This platform represents a structured system of connected modeling-related tools and data that 

provide a consistent and transparent basis for assessing the air quality response to projected 

changes in emissions. The base year of data used to construct this platform includes emissions 

and meteorology for 2005. The platform was developed by the U.S. EPA’s Office of Air Quality 

Planning and Standards in collaboration with the Office of Research and Development and is 

intended to support a variety of regulatory and research model applications and analyses. This 

modeling platform and analysis is fully described below. 

1

 Byun, D.W., and K. L. Schere, 2006: Review of the Governing Equations, Computational Algorithms, and Other 

Components of the Models-3 Community Multiscale Air Quality (CMAQ) Modeling System. Applied Mechanics 

Reviews, Volume 59, Number 2 (March 2006), pp. 51-77. 

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A. Model version 

CMAQ is a non-proprietary computer model that simulates the formation and fate of 

photochemical oxidants, primary and secondary PM concentrations, acid deposition, and air 

toxics, over regional and urban spatial scales for given input sets of meteorological conditions 

and emissions. The CMAQ model version 4.7 was most recently peer-reviewed in February of 

2009 for the U.S. EPA.2 The CMAQ model is a well-known and well-respected tool and has 

been used in numerous national and international applications.3,4,5,6 This 2005 multi-pollutant 

modeling platform used the latest publicly-released CMAQ version 4.77

 with a minor internal 

change made by the U.S. EPA CMAQ model developers intended to speed model runtimes when 

only a small subset of toxics species are of interest.8

 This version reflects updates in a number of 

areas to improve the underlying science, including: 

1) an enhanced secondary organic aerosol (SOA) mechanism to include chemistry of 

isoprene, sesquiterpene, and aged in-cloud biogenic SOA in addition to terpene, 

2) an improved vertical convective mixing algorithm; 

3) an improved heterogeneous reaction involving nitrate formation, and 

4) an updated gas-phase chemistry mechanism, Carbon Bond 05 (CB05), with extensions 

to model explicit concentrations of air toxic species as well as chlorine and mercury. 

This mechanism, CB05-toxics, also computes concentrations of species that are involved in 

aqueous chemistry and that are precursors to aerosols. Chapter 3 of the RIA discusses in detail 

2

 Allen, D., Burns, D., Chock, D., Kumar, N., Lamb, B., Moran, M. (February 2009 Draft Version). Report on the 

Peer Review of the Atmospheric Modeling and Analysis Division, NERL/ORD/EPA. U.S. EPA, Research Triangle 

Park, NC 

3

 Hogrefe, C., Biswas, J., Lynn, B., Civerolo, K., Ku, J.Y., Rosenthal, J., et al. (2004). Simulating regional-scale 

ozone climatology over the eastern United States: model evaluation results. Atmospheric Environment, 38(17),
 

2627-2638. 

6 United States Environmental Protection Agency. (2008). Technical support document for the final
 

locomotive/marine rule: Air quality modeling analyses. Research Triangle Park, N.C.: U.S. Environmental 

Protection Agency, Office of Air Quality Planning and Standards, Air Quality Assessment Division. 

5 Lin, M., Oki, T., Holloway, T., Streets, D.G., Bengtsson, M., Kanae, S. (2008). Long-range transport of acidifying
 

substances in East Asia-Part I: Model evaluation and sensitivity studies. Atmospheric Environment, 42(24), 5939­

5955.
 

6 Lin, M., Oki, T., Holloway, T., Streets, D.G., Bengtsson, M., Kanae, S. (2008). Long-range transport of acidifying
 

substances in East Asia-Part I: Model evaluation and sensitivity studies. Atmospheric Environment, 42(24), 5939­

5955. 

7 CMAQ version 4.7 was released on December, 2008. It is available from the Community Modeling and Analysis 

System (CMAS) as well as previous peer-review reports at: http://www.cmascenter.org. 8 CMAQ version 4.7 was released on December, 2008. It is available from the Community Modeling and Analysis 

System (CMAS) as well as previous peer-review reports at: http://www.cmascenter.org.
 

4 
 

 

the chemical mechanism, SOA formation, and details about the improvements made to the SOA 

mechanism within this recent release of CMAQ. 

B. Model domain and grid resolution 

The CMAQ modeling analyses were performed for a domain covering the continental 

United States, as shown in Figure II-1. This domain has a parent horizontal grid of 36 km with 

two finer-scale 12 km grids over portions of the eastern and western U.S. The model extends 

vertically from the surface to 100 millibars (approximately 15 km) using a sigma-pressure 

coordinate system. Air quality conditions at the outer boundary of the 36 km domain were taken 

from a global model and did not change over the simulations. In turn, the 36 km grid was only 

used to establish the incoming air quality concentrations along the boundaries of the 12 km grids. 

Only the finer grid data were used in determining the impacts of the RFS2 program changes. 

Table II-1 provides some basic geographic information regarding the CMAQ domains. 

Table II-1. Geographic elements of domains used in RFS2 modeling. 

CMAQ Modeling Configuration 

National Grid Western U.S. Fine Grid Eastern U.S. Fine Grid 

Map Projection Lambert Conformal Projection 

Grid Resolution 36 km 12 km 12 km 

Coordinate Center 97 deg W, 40 deg N 

True Latitudes 33 deg N and 45 deg N 

Dimensions 148 x 112 x 14 213 x 192 x 14 279 x 240 x 14 

Vertical extent 14 Layers: Surface to 100 millibar level (see Table II-3) 

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Figure II-1. Map of the CMAQ modeling domain. The black outer box denotes the 36 km 

national modeling domain; the red inner box is the 12 km western U.S. fine grid; and the 

blue inner box is the 12 km eastern U.S. fine grid. 

C. Valid Modeling Days 

 The 36 km and both 12 km CMAQ modeling domains were modeled for the entire year 

of 2005.9 For the 8-hour ozone results, we are only using modeling results from the period 

between May 1 and September 30, 2005. This 153-day period generally conforms to the ozone 

season across most parts of the U.S. and contains the majority of days with observed high ozone 

concentrations in 2005. Data from the entire year were utilized when looking at the toxics 

impacts from the regulation. 

Normally, all 365 model days would also have been used in the estimation of PM2.5 and 

visibility impacts; however during the RFS2 modeling, an error was discovered in the aqueous 

9 We also modeled 10 days at the end of December 2004 as a modeled "ramp up" period. These days are used to 

minimize the effects of initial conditions and are not considered as part of the output analyses. 

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phase chemistry routines of CMAQ v4.7. This error10 caused simulated hourly sulfate 

concentrations to increase sporadically and in an unrealistic manner over a very limited number 

of grid-cell hours over the RFS2 simulations. While this artifact has subsequently been removed 

from CMAQ v4.7, the RFS2 modeling schedule did not allow for the simulations to be redone. 

Instead, we simply invalidated any day that contained evidence of the aqueous phase problem 

and used the remaining data to determine the “true” model signal from the RFS2 scenarios. The 

following invalidation criteria were used. Any day in which there were five or more grid cellhours that had greater than 50 ug/m3

 difference in sulfate concentrations between the future base 

and control cases was invalidated. Additionally any day with a single grid cell-hour difference 

exceeding 250 ug/m3 was invalidated. Based on these invalidation criteria, nine days were 

removed from the EUS12 analysis and two days were removed from the WUS12 analysis11. 

D. Model Inputs: Emissions, Meteorology and Boundary Conditions 

The 2005-based CMAQ modeling platform was used for the air quality modeling of 

future baseline emissions and control scenarios. As noted in the introduction, in addition to the 

CMAQ model, the modeling platform also consists of the base- and future-year emissions 

estimates (both anthropogenic and biogenic), meteorological fields, as well as initial and 

boundary condition data which are all inputs to the air quality model. 

1. Base Year and Future Baseline Emissions: The emissions modeling TSD, found in the 

docket for this rule (EPA-HQ-OAR-2005-0161), contains a detailed discussion of the emissions 

inputs used in our air quality modeling as well as Section 3.1 in the final RFS2 RIA. We have 

provided a brief summary of the base year and future baseline emissions used for the air quality 

modeling. The emissions data used in the base year and each of the future base cases are based 

on the 2005 v4 platform. The RFS2 cases use some different emissions data than the official v4 

platform for two reasons: (1) the RFS2 modeling was done prior to the completion of the 

platform and (2) the RFS2 modeling used data intended only for the rule development and not 

for general application. The US EGU point source emissions estimates for all 2022 future year 

base cases are based on an Integrated Planning Model (IPM) run for criteria pollutants, 

hydrochloric acid, and mercury in 2020. The year 2020 was used since it was the year closest to 

the 2022 modeling year supported by the IPM model. Both control and growth factors were 

applied to a subset of the 2005 non-EGU point and nonpoint to create each of the 2022 future 

base cases. The 2002 v3.1 platform 2020 projection factors were the starting point for most of 

the RFS2 year 2022 SMOKE-based projections. Ethanol plant replacements and additions were 

included in the 2005 base and 2022 future baselines as well as biodiesel additions and portable 

fuel containers. 

It should be noted that the emission inventories used in the air quality and benefits 

modeling were enhanced compared to what was described in the proposal, but did not include 

10 This model artifact is discussed in more detail in an August 5th, 2009 document prepared by Shawn Roselle and 

Ann Marie Carlton. This document has been placed in the rule docket (EPA-HQ-OAR-2005-0161-DRAFT-2902). 

11 The days to be removed for the EUS12 are: 1/25, 2/25, 3/04, 3/05, 3/13, 3/14. 12/08, 12/09, 12/12. The days to 

be removed for the WUS12 are: 1/04 and 1/27. 

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some of the later enhancements and corrections of the final emission inventories presented in this 

FRM. 

2. RFS2 Modeling Scenarios: As part of our analysis for this rulemaking, the CMAQ 

modeling system was used to calculate daily and annual PM2.5 concentrations, 8-hour ozone 

concentrations, annual and seasonal air toxics concentrations, and total nitrogen and sulfur 

deposition levels for each of the following emissions scenarios: 

2005 base year 

2022 baseline projection (RFS1 Mandate) of 7.5 billion gallons of renewable fuels 

2022 baseline projection (Annual Energy Outlook (AEO) 2007) volume of 

roughly 14 billion gallons of renewable fuels 

2022 control case projection (implementation of RFS2; also referred to as EISA 

(Energy Independence and Security Act of 2007) 

Model predictions are used in a relative sense to estimate scenario-specific, future-year 

design values of PM2.5 and ozone. This is done by calculating the simulated air quality ratios 

between any particular future year simulation and the 2005 base. These predicted change ratios 

are then applied to ambient base year design values. The design value projection methodology 

used here followed EPA guidance12 for such analyses. Additionally, the raw model outputs are 

also used in a relative sense as inputs to the health and welfare impact functions of the benefits 

analysis. Model predictions for air toxics as well as nitrogen and sulfur deposition were 

analyzed for an absolute change and percent change between the control case and two future 

baselines. 

3. Sensitivity analyses looking at impacts of chosen speciation profiles: During the 

course of the RFS2 modeling, two issues arose concerning the approaches used to speciate 

certain classes of mobile source emissions into the chemical mechanism used by CMAQ. In 

order to determine what effect, if any, these particular RFS2 speciation assumptions may have 

had on the modeling results, a limited set of sensitivity modeling runs were performed and are 

summarized below. 

The first analysis considered the impacts of an error in the emissions processing of 

nonroad gasoline emissions. Inadvertently, the speciation profiles for highway sources, which 

reflect a mix of pre-/post-Tier 2 vehicles and a mix of E0, E10, and E85 gasoline, had also been 

applied to nonroad gasoline engines which do not have similar advanced Tier-2 emissions 

controls, nor do they use E85 gasoline. The concern was that this error would result in potential 

overestimates of ethanol and potential underestimates of acetaldehyde in the control case. The 

corrected RFS2 emissions contained 9.1% less ethanol and 1.1% more acetaldehyde than what 

was modeled in the original scenario. The RFS2 control case was remodeled with the 

appropriate speciation profiles for four months in 2005 (January, April, July, and October). The 

12 U.S. EPA, Guidance on the Use of Models and Other Analyses in Attainment Demonstrations for the 8-hour 

Ozone NAAQS; EPA-454/R-05-002; Research Triangle Park, NC; October 2005. 

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sensitivity modeling showed that the original simulations (i.e., the ones summarized herein) do 

overestimate the expected ethanol changes between the baselines (i.e., AEO and RFS1) and the 

control case (RFS2). However, the CMAQ modeling indicated that the impacts of the speciation 

fixes were very small for ozone, PM2.5, and key toxics species. Outside of ethanol, the impacts 

of the fix were generally at least one order of magnitude smaller than the differences between the 

RFS1 base and the control scenario. As a result, it was determined that the original modeling 

was sufficient for isolating the impacts of RFS2. 

The second analysis evolved out of initial comparisons of the RFS1 mandate reference 

case with the RFS2 control case, where the modeling showed decreases in acetaldehyde 

concentrations in the summer and winter in urban areas. Decreases are less pronounced in winter 

when there is less secondary formation of acetaldehyde. The main reason for the decrease in 

urban areas is determined to be due to reductions in emissions of certain acetaldehyde 

precursors. In particular, reductions in alkenes (olefins) were noted, driven by differences in the 

E0 gasoline headspace speciation profiles used for the control case and the reference cases, as 

discussed in Section 3.4.1.3 of the RFS2 RIA. Headspace profiles are used to speciate 

hydrocarbon emissions from gasoline storage, gasoline distribution, and gas cans. After the 

initial modeling was completed, EPA noticed that the headspace profiles used in the reference 

case scenarios exhibited a reduction in alkene levels going from E0 to E10 that was inconsistent 

with what one would expect as a result of increased ethanol use. In these cases, the E0 gasoline 

headspace profile has 13% of the VOC as alkenes and the E10 profile has an alkene content of 

4%. To address this issue, EPA conducted a sensitivity analysis by adjusting the E0 headspace 

profile in the RFS1 mandate reference case for the Eastern U.S. modeling domain13 (based on the 

assumption that the emissions have an alkene content of 4%, consistent with the percent alkene 

content of the E10 headspace profile14). A sensitivity analysis was conducted for the month of 

July and EPA compared results with the control case for the following two cases: 

1) RFS1 case with no change in alkene levels between headspace profiles for E0 and 

E10 (i.e., adjusted E0 profile) 

2) RFS1 case with higher alkene levels for E0 headspace profile 

Because of these uncharacteristic differences, EPA reran the control case using the 

adjusted E0 gasoline headspace profile. Due to time constraints, we were not able to make this 

improvement for the reference cases. Thus, alkene levels associated with the E0 use are lower in 

the control case than the reference cases, leading to a reduction in secondarily formed 

acetaldehyde. 

The results of the sensitivity analysis showed that acetaldehyde levels were significantly 

higher for the comparison between Case 1 and the control case than for the comparison between 

Case 2 and the control case. The sensitivity analysis thus confirmed that the decrease in these 

13 Details of the sensitivity run are discussed in the emissions modeling TSD, found in the docket for this rule (EPAHQ-OAR-2005-0161). 

14 U.S. Environmental Protection Agency. 2010. Hydrocarbon Composition of Gasoline Vapor Emissions from 

Enclosed Fuel Tanks. Draft Report EPA-420-D-10-001, January 2010. 

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acetaldehyde precursors between the reference cases and the control case E0 headspace profile is 

driving the decrease in ambient concentrations of acetaldehyde in urban areas. Thus, while the 

air quality modeling results presented in the RFS2 RIA and in Section III.C.1 below suggest 

impacts of increased renewable fuel use on ambient acetaldehyde are not substantial and there 

may be decreases in urban areas, there is considerable uncertainty associated with these results. 

In fact, if the reference cases were rerun with revised E0 headspace profiles, some of the 

observed decreases could become increases. 

4. Meteorological Input Data: The gridded meteorological input data for the entire year 

of 2005 were derived from simulations of the Pennsylvania State University / National Center for 

Atmospheric Research Mesoscale Model. This model, commonly referred to as MM5, is a 

limited-area, nonhydrostatic, terrain-following system that solves for the full set of physical and 

thermodynamic equations which govern atmospheric motions.15 Meteorological model input 

fields were prepared separately for each of the three domains shown in Figure II-1 using MM5 

version 3.7.4. The MM5 simulations were run on the same map projection as CMAQ. 

All three meteorological model runs configured similarly. The selections for key MM5 

physics options are shown below: 

• Pleim-Xiu PBL and land surface schemes 

• Kain-Fritsh 2 cumulus parameterization 

• Reisner 2 mixed phase moisture scheme 

• RRTM longwave radiation scheme 

• Dudhia shortwave radiation scheme 

Three dimensional analysis nudging for temperature and moisture was applied above the 

boundary layer only. Analysis nudging for the wind field was applied above and below the 

boundary layer. The 36 km domain nudging weighting factors were 3.0 x 104

 for wind fields and 

temperatures and 1.0 x 105

 for moisture fields. The 12 km domain nudging weighting factors 

were 1.0 x 104 for wind fields and temperatures and 1.0 x 105 for moisture fields. 

All three sets of model runs were conducted in 5.5 day segments with 12 hours of overlap 

for spin-up purposes. All three domains contained 34 vertical layers with an approximately 38 m 

deep surface layer and a 100 millibar top. The MM5 and CMAQ vertical structures are shown in 

Table II-3 and do not vary by horizontal grid resolution. 

Table II-3. Vertical layer structure for MM5 and CMAQ (heights are layer top). 

CMAQ Layers MM5 Layers Sigma P Approximate 

Height (m) 

Approximate 

Pressure (mb) 

0 0 1.000 0 1000 

1 1 0.995 38 995 

2 2 0.990 77 991 

3 3 0.985 115 987 

15 Grell, G., J. Dudhia, and D. Stauffer, 1994: A Description of the Fifth-Generation Penn State/NCAR Mesoscale 

Model (MM5), NCAR/TN-398+STR., 138 pp, National Center for Atmospheric Research, Boulder CO. 

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4 0.980 154 982 

4 5 0.970 232 973 

6 0.960 310 964 

5 7 0.950 389 955 

8 0.940 469 946 

6 

9 0.930 550 937 

10 0.920 631 928 

11 0.910 712 919 

7 

12 0.900 794 910 

13 0.880 961 892 

14 0.860 1,130 874 

8 

15 0.840 1,303 856 

16 0.820 1,478 838 

17 0.800 1,657 820 

9 18 0.770 1,930 793 

19 0.740 2,212 766 

10 20 0.700 2,600 730 

21 0.650 3,108 685 

11 22 0.600 3,644 640 

23 0.550 4,212 595 

12 

24 0.500 4,816 550 

25 0.450 5,461 505 

26 0.400 6,153 460 

13 

27 0.350 6,903 415 

28 0.300 7,720 370 

29 0.250 8,621 325 

30 0.200 9,625 280 

14 

31 0.150 10,764 235 

32 0.100 12,085 190 

33 0.050 13,670 145 

34 0.000 15,674 100 

The meteorological outputs from all three MM5 sets were processed to create modelready inputs for CMAQ using the Meteorology-Chemistry Interface Processor (MCIP), version 

3.4, to derive the specific inputs to CMAQ.16 

Before initiating the air quality simulations, it is important to identify the biases and 

errors associated with the meteorological modeling inputs. The 2005 MM5 model performance 

evaluations used an approach which included a combination of qualitative and quantitative 

analyses to assess the adequacy of the MM5 simulated fields. The qualitative aspects involved 

comparisons of the model-estimated synoptic patterns against observed patterns from historical 

weather chart archives. Additionally, the evaluations compared spatial patterns of monthly 

average rainfall and monthly maximum planetary boundary layer (PBL) heights. Qualitatively, 

the model fields closely matched the observed synoptic patterns, which is not unexpected given 

the use of nudging. The operational evaluation included statistical comparisons of 

model/observed pairs (e.g., mean normalized bias, mean normalized error, index of agreement, 

root mean square errors, etc.) for multiple meteorological parameters. For this portion of the 

16 Byun, D.W., and Ching, J.K.S., Eds, 1999. Science algorithms of EPA Models-3 Community Multiscale Air 

Quality (CMAQ modeling system, EPA/600/R-99/030, Office of Research and Development). 

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evaluation, five meteorological parameters were investigated: temperature, humidity, shortwave 

downward radiation, wind speed, and wind direction. The three individual MM5 evaluations are 

described elsewhere.17,18,19 It was ultimately determined that the bias and error values associated 

with all three sets of 2005 meteorological data were generally within the range of past 

meteorological modeling results that have been used for air quality applications. 

5. Initial and Boundary Conditions: The lateral boundary and initial species 

concentrations are provided by a three-dimensional global atmospheric chemistry model, the 

GEOS-CHEM20 model (standard version 7-04-1121). The global GEOS-CHEM model simulates 

atmospheric chemical and physical processes driven by assimilated meteorological observations 

from the NASA’s Goddard Earth Observing System (GEOS). This model was run for 2005 with 

a grid resolution of 2.0 degree x 2.5 degree (latitude-longitude) and 30 vertical layers up to 100 

mb. The predictions were used to provide one-way dynamic boundary conditions at three-hour 

intervals and an initial concentration field for the 36-km CMAQ simulations. The future base 

conditions from the 36 km coarse grid modeling were used as the initial/boundary state for all 

subsequent 12 km finer grid modeling. 

E. CMAQ Base Case Model Performance Evaluation 

1. PM2.5: An operational model performance evaluation for PM2.5 and its related 

speciated components (e.g., sulfate, nitrate, elemental carbon, organic carbon, etc.) was 

conducted using 2005 state/local monitoring data in order to estimate the ability of the CMAQ 

modeling system to replicate base year concentrations. In summary, model performance 

statistics were calculated for observed/predicted pairs of daily/monthly/seasonal/annual 

concentrations. Statistics were generated for the following geographic groupings: domain wide, 

Eastern vs. Western (divided along the 100th meridian), and each Regional Planning 

Organization (RPO) region22. The “acceptability” of model performance was judged by 

17 Baker K. and P. Dolwick. Meteorological Modeling Performance Evaluation for the Annual 2005 Eastern U.S. 

12-km Domain Simulation, USEPA/OAQPS, February 2, 2009. 

18 Baker K. and P. Dolwick. Meteorological Modeling Performance Evaluation for the Annual 2005 Western U.S. 

12-km Domain Simulation, USEPA/OAQPS, February 2, 2009. 

19 Baker K. and P. Dolwick. Meteorological Modeling Performance Evaluation for the Annual 2005 Continental 

U.S. 36-km Domain Simulation, USEPA/OAQPS, February 2, 2009. 

20 Yantosca, B., 2004. GEOS-CHEMv7-01-02 User’s Guide, Atmospheric Chemistry Modeling 

Group, Harvard University, Cambridge, MA, October 15, 2004. 

21 Henze, D.K., J.H. Seinfeld, N.L. Ng, J.H. Kroll, T-M. Fu, D.J. Jacob, C.L. Heald, 2008. Global modeling of 

secondary organic aerosol formation from aromatic hydrocarbons: high-vs.low-yield pathways. Atmos. Chem. Phys., 

8, 2405-2420. 

22 Regional Planning Organization regions include: Mid-Atlantic/Northeast Visibility Union (MANEVU), Midwest 

Regional Planning Organization – Lake Michigan Air Directors Consortium (MWRPO-LADCO), Visibility 

Improvement State and Tribal Association of the Southeast (VISTAS), Central States Regional Air Partnership 

(CENRAP), and the Western Regional Air Partnership (WRAP). 

12 
 

 

 

 

comparing our CMAQ 2005 performance results to the range of performance found in recent 

regional PM2.5 model applications for other, non-EPA studies23. Overall, the fractional bias, 

fractional error, normalized mean bias, and normalized mean error statistics shown in Table II-4 

are within the range or close to that found by other groups in recent applications. The model 

performance results give us confidence that our application of CMAQ using this modeling 

platform provides a scientifically credible approach for assessing PM2.5 concentrations for the 

purposes of the RFS2 assessment. A detailed summary of the 2005 CMAQ model performance 

evaluation is available in Appendix B24. 

Table II-4. 2005 CMAQ annual PM2.5 species model performance statistics. 

CMAQ 2005 Annual No. of 

Obs. NMB (%) NME (%) FB (%) FE (%) 

PM2.5 

Total Mass 

STN 

12-km EUS 11797 -0.8 37.6 -2.4 38.7 

12-km WUS 3440 -10.0 45.0 -9.5 44.4 

Midwest 2318 8.5 35.2 9.2 33.5 

Northeast 2977 10.8 41.6 9.9 38.8 

Southeast 2960 -13.7 34.0 -14.5 37.1 

Central U.S. 2523 -6.3 39.8 -9.8 44.3 

West 2826 -10.9 46.1 -10.6 45.0 

IMPROVE 

12-km EUS 9321 -6.4 41.6 -7.2 43.6 

12-km WUS 10411 -19.9 44.6 -21.9 48.4 

Midwest 571 1.3 36.8 1.3 37.2 

Northeast 2339 12.1 47.7 8.1 44.3 

Southeast 1694 -17.6 37.5 -16.9 43.1 

Central U.S. 2376 -13.3 41.7 -11.9 46.2 

West 9258 -22.9 44.8 -23.5 48.6 

Sulfate 

STN 

12-km EUS 13897 -12.3 33.2 -9.2 35.9 

12-km WUS 3920 -17.0 42.3 -7.8 42.8 

Midwest 2495 -5.2 34.0 0.7 34.8 

Northeast 3441 -7.7 32.1 -4.0 33.9 

Southeast 3499 -14.5 30.9 -12.2 33.4 

Central U.S. 2944 -22.5 37.2 -19.5 41.6 

West 3157 -15.5 45.8 -6.7 44.0 

IMPROVE 

12-km EUS 9034 -15.2 34.5 -6.2 38.9 

12-km WUS 10002 -14.4 41.0 2.7 44.5 

Midwest 531 -12.7 32.5 -5.0 34.6 

Northeast 2253 -7.7 34.3 -0.2 37.3 

Southeast 1685 -17.8 32.7 -12.2 36.2 

Central U.S. 2350 -23.5 36.6 -16.1 40.7 

West 8896 -10.5 42.3 5.0 45.1 

CASTNet 12-km EUS 3170 -19.3 24.8 -18.5 27.8 

23 These other modeling studies represent a wide range of modeling analyses which cover various models, model 

configurations, domains, years and/or episodes, chemical mechanisms, and aerosol modules. 

24 U.S. Environmental Protection Agency, Air Quality Modeling Technical Support Document: Changes to 

Renewable Fuel Standard Program, Appendix B: CMAQ Model Performance Evaluation for Ozone, Particulate 

Matter and Toxics. January, 2010 (EPA-454/R-10-001A). 

13 
 

12-km WUS 1142 -24.6 33.6 -16.6 35.2 

Midwest 615 -16.7 23.4 -14.8 24.8 

Northeast 786 -14.2 22.6 -12.3 24.8 

Southeast 1099 -21.5 24.7 -23.6 27.7 

Central U.S. 300 -32.2 34.3 -33.6 38.4 

West 1091 -23.7 33.8 -15.8 35.2 

Nitrate 

STN 

12-km EUS 12741 25.5 70.4 -8.1 78.1 

12-km WUS 3655 -41.7 65.3 -70.8 97.5 

Midwest 2495 29.8 64.7 17.1 63.9 

Northeast 3442 37.0 73.9 3.2 73.6 

Southeast 3499 13.1 78.2 -27.5 86.0 

Central U.S. 1812 5.2 58.8 -6.2 71.6 

West 31339 -47.3 65.4 -79.1 99.9 

IMPROVE 

12-km EUS 9027 34.2 86.9 -31.6 101.6 

12-km WUS 9987 -29.7 72.5 -93.8 124.0 

Midwest 531 20.7 69.8 -7.3 82.1 

Northeast 2248 66.4 106.9 -1.0 95.4 

Southeast 1685 42.5 106.6 -37.5 105.2 

Central U.S. 2350 22.8 72.7 -20.5 95.0 

West 8881 -45.7 75.6 -102.3 128.4 

Total 

Nitrate 

(NO3 + 

HNO3) 

CASTNet 

12-km EUS 3170 27.3 40.3 21.9 38.1 

12-km WUS 1142 -3.3 34.5 6.4 39.9 

Midwest 615 26.1 37.4 26.9 34.1 

Northeast 786 40.6 46.0 34.4 42.4 

Southeast 1099 25.7 41.4 17.2 39.2 

Central U.S. 300 10.4 33.9 7.3 33.3 

West 1091 -4.7 35.7 6.4 40.5 

Ammonium 

STN 

12-km EUS 13897 6.7 42.3 12.6 45.4 

12-km WUS 3893 -14.9 55.3 7.1 55.0 

Midwest 2495 14.3 42.0 22.3 42.2 

Northeast 3498 14.7 44.3 25.0 46.3 

Southeast 3882 0.8 39.1 6.5 42.0 

Central U.S. 3059 -4.3 43.6 -0.2 50.4 

West 3130 -20.5 59.0 5.8 57.2 

CASTNet 

12-km EUS 3170 -1.3 34.6 0.4 35.8 

12-km WUS 1142 -14.5 38.8 -12.1 40.1 

Midwest 615 8.1 34.6 12.8 33.3 

Northeast 786 6.2 37.2 11.3 35.9 

Southeast 1099 -13.6 32.6 -13.7 36.5 

Central U.S. 300 -4.2 35.4 -1.1 39.6 

West 1091 -20.8 39.1 -13.9 40.2 

Elemental 

Carbon 

STN 

12-km EUS 14038 25.9 66.0 18.2 54.3 

12-km WUS 3814 31.1 77.7 19.5 62.5 

Midwest 2502 18.7 51.7 20.1 47.1 

Northeast 3479 37.7 70.5 26.7 54.7 

Southeast 3877 10.7 59.1 8.1 49.4 

Central U.S. 3221 48.1 86.3 26.5 64.3 

West 3015 38.7 82.8 21.0 65.1 

IMPROVE 12-km EUS 8668 -25.9 49.1 -28.3 56.0 

12-km WUS 9495 -10.2 57.2 -17.8 60.4 

Midwest 602 -16.8 41.8 -28.3 50.4 

14 
 

 

Northeast 2117 -4.8 48.8 -15.5 54.1 

Southeast 1584 -46.1 51.4 -51.5 62.8 

Central U.S. 2123 -31.3 49.5 -30.1 56.5 

West 8518 -9.6 58.2 -18.2 61.5 

Organic 

Carbon 

STN 

12-km EUS 12619 -35.1 52.6 -32.5 63.9 

12-km WUS 3582 -32.1 56.7 -28.2 61.3 

Midwest 2380 -37.3 51.9 -31.0 62.5 

Northeast 3323 -17.4 52.7 -13.7 60.3 

Southeast 3802 -45.7 52.9 -48.7 66.7 

Central U.S. 2259 -38.8 53.4 -37.3 66.9 

West 3060 -31.7 57.6 -27.8 61.4 

IMPROVE 

12-km EUS 8662 -29.9 50.6 -34.3 59.1 

12-km WUS 9495 -24.0 57.1 -29.4 62.8 

Midwest 601 -33.1 43.6 -39.3 53.2 

Northeast 2116 -7.7 52.4 -14.4 53.5 

Southeast 1587 -37.8 46.7 -48.0 60.2 

Central U.S. 2123 -42.5 54.2 -46.8 65.2 

West 8518 -22.3 57.3 -28.1 62.7 

2. Ozone: An operational model performance evaluation for hourly and eight-hour daily 

maximum ozone was conducted in order to estimate the ability of the CMAQ modeling system 

to replicate the base year concentrations for the 12-km Eastern and Western United States 

domain shown in Figure II-1. Ozone measurements from 1194 sites (817 in the East and 377 in 

the West) were included in the evaluation and were taken from the 2005 State/local monitoring 

site data in the Air Quality System (AQS) Aerometric Information Retrieval System (AIRS). 

The ozone metrics covered in this evaluation include one-hour daily maximum ozone 

concentrations and eight-hour daily maximum ozone concentrations. The evaluation principally 

consists of statistical assessments of model versus observed pairs that were paired in time and 

space on an hourly and/or daily basis, depending on the sampling frequency of each 

measurement site (measured data). This ozone model performance was limited to the ozone 

season (May through September) that was modeled for the RFS2 final rule. Appendix B 

contains a more detailed summary of ozone model performance over the 12km Eastern and 

Western U.S. grid. A summary of the evaluation is presented here. 

As with the national, annual PM2.5 CMAQ modeling, the “acceptability” of model 

performance was judged by comparing our CMAQ 2005 performance results to the range of 

performance found in recent regional ozone model applications (e.g., EPA’s Proposal to 

Designate an Emissions Control Area for Nitrogen Oxides 25 and the Clean Air Interstate Rule26). 

Overall, the normalized mean bias and error (NMB and NME), as well as the fractional bias and 

error (FB and FE) statistics shown in Tables II-5 and II-6 indicate that CMAQ-predicted 2005 

hourly and eight-hour daily maximum ozone residuals (i.e., observation vs. model predictions) 

are within the range of other recent regional modeling applications. The CMAQ model 

25 U.S. Environmental Protection Agency, Proposal to Designate an Emissions Control Area for Nitrogen Oxides, 

Sulfur Oxides, and Particulate Matter: Technical Support Document. EPA-420-R-007, 329pp., 2009. 

(http://www.epa.gov/otaq/regs/nonroad/marine/ci/420r09007.pdf) 

26 U.S. Environmental Protection Agency; Technical Support Document for the Final Clean Air Interstate Rule: Air 

Quality Modeling; Office of Air Quality Planning and Standards; Research Triangle Park, NC; March 2005. 

15 
 

 

 

performance results give us confidence that our applications of CMAQ using this modeling 

platform provide a scientifically credible approach for assessing ozone concentration changes 

resulting from the final RFS2 emissions reductions. 

Table II-5. 2005 CMAQ one-hour daily maximum ozone model performance statistics 

calculated for a threshold of 40 ppb. 

CMAQ 2005 One-Hour Maximum Ozone: 

Threshold of 40 ppb No. of Obs. NMB (%) NME (%) FB (%) FE (%) 

May 

12-km EUS 21394 -1.6 11.5 -0.8 11.6 

12-km WUS 9631 -3.4 12.8 -2.8 12.7 

Midwest 4418 0.8 10.0 1.0 10.2 

Northeast 4102 5.4 11.8 5.9 11.7 

Southeast 6424 -3.6 11.3 -3.0 11.5 

Central U.S. 4328 -6.4 13.4 -5.5 13.4 

West 8294 -3.5 12.9 -3.0 12.8 

June 

12-km EUS 19517 -3.5 12.8 -2.8 12.9 

12-km WUS 9056 -3.7 13.0 -3.2 13.0 

Midwest 4639 -4.6 12.3 -4.0 12.4 

Northeast 4148 -1.0 14.1 -0.1 14.2 

Southeast 4644 -2.7 12.5 -2.2 12.6 

Central U.S. 4062 -6.2 13.2 -5.4 13.3 

West 7737 -4.0 13.1 -3.6 13.1 

July 

12-km EUS 19692 1.2 14.2 1.8 14.1 

12-km WUS 9443 0.4 16.0 1.0 15.8 

Midwest 4923 0.4 12.7 0.9 12.6 

Northeast 4445 4.2 15.2 4.8 14.9 

Southeast 4733 4.2 15.1 4.6 14.8 

Central U.S. 3521 -3.8 14.8 -3.1 14.9 

West 8168 0.2 16.2 0.7 16.0 

August 

12-km EUS 19643 0.1 13.9 0.8 13.8 

12-km WUS 9562 -0.8 15.5 -0.6 15.5 

Midwest 4549 0.2 12.2 1.0 12.3 

Northeast 4139 0.2 13.2 1.2 13.1 

Southeast 5303 3.6 14.9 3.9 14.5 

Central U.S. 3589 -4.1 16.2 -2.9 16.1 

West 8357 -1.0 15.7 -1.0 15.7 

September 

12-km EUS 18085 -2.2 12.0 -1.3 12.0 

12-km WUS 8725 -3.6 14.1 -3.2 14.3 

Midwest 4002 -3.6 10.7 -3.0 10.8 

Northeast 3667 -1.8 11.3 -0.7 11.3 

Southeast 5259 -0.1 12.1 0.8 12.1 

Central U.S. 3286 -6.1 14.5 -5.1 14.5 

West 7530 -4.1 14.3 -3.8 14.4 

Seasonal Aggregate 

(May – September) 

12-km EUS 98331 -1.2 12.9 -0.5 12.8 

12-km WUS 46417 -2.1 14.3 -1.7 14.2 

Midwest 22531 -1.4 11.7 -0.8 11.7 

Northeast 20501 1.4 13.3 2.3 13.1 

Southeast 26363 0.1 13.1 0.7 13.0 

Central U.S. 18786 -5.4 14.4 -4.4 14.4 

West 40086 -2.3 14.5 -2.1 14.4 

16 
 

 

 

Table II-6. 2005 CMAQ eight-hour daily maximum ozone model performance statistics 

calculated for a threshold of 40 ppb. 

CMAQ 2005 Eight-Hour Maximum 

Ozone: Threshold of 40 ppb No. of Obs. NMB (%) NME (%) FB (%) FE (%) 

May 

12-km EUS 19310 -1.0 10.9 -0.4 11.0 

12-km WUS 8445 -1.6 12.0 -1.2 12.0 

Midwest 3858 0.2 10.0 0.7 10.2 

Northeast 3528 5.2 11.4 5.4 11.2 

Southeast 6019 -2.1 10.5 -1.6 10.6 

Central U.S. 3927 -5.8 12.8 -5.2 13.0 

West 7234 -1.8 12.1 -1.5 12.0 

June 

12-km EUS 17404 -2.1 11.9 -1.5 12.0 

12-km WUS 8102 -1.9 11.9 -1.6 11.9 

Midwest 4324 -3.8 11.6 -3.4 11.8 

Northeast 3590 0.3 13.1 1.0 13.2 

Southeast 3924 -0.3 11.4 0.1 11.5 

Central U.S. 3663 -5.5 12.1 -5.0 12.3 

West 6889 -2.2 12.1 -2.0 12.1 

July 

12-km EUS 17045 3.3 13.4 3.6 13.3 

12-km WUS 8556 3.7 15.0 3.9 14.7 

Midwest 4429 1.8 11.8 2.3 11.8 

Northeast 3856 6.6 14.6 6.8 14.3 

Southeast 3806 7.4 15.0 7.3 14.5 

Central U.S. 3057 -2.3 13.2 -2.1 13.5 

West 7407 3.5 15.1 3.6 14.9 

August 

12-km EUS 16953 1.9 12.9 2.2 12.9 

12-km WUS 8523 1.6 13.9 1.5 13.9 

Midwest 4027 0.9 11.3 1.4 11.4 

Northeast 3530 1.4 12.3 2.0 12.2 

Southeast 4447 7.4 14.7 7.2 14.1 

Central U.S. 3096 -3.4 14.4 -3.1 14.8 

West 7469 1.4 14.1 1.2 14.0 

September 

12-km EUS 15190 -1.8 11.2 -1.3 11.3 

12-km WUS 7465 -2.4 13.4 -2.6 13.9 

Midwest 3265 -4.2 10.2 -4.0 10.4 

Northeast 2856 -2.3 10.6 -1.8 10.7 

Southeast 4647 1.5 11.2 2.1 11.2 

Central U.S. 2798 -6.5 13.6 -6.1 14.0 

West 6446 -2.9 13.7 -3.1 14.1 

Seasonal Aggregate 

(May – September) 

12-km EUS 85902 0.1 12.1 0.5 12.1 

12-km WUS 41091 0.0 13.3 0.1 13.3 

Midwest 19903 -0.9 11.1 -0.5 11.2 

Northeast 17360 2.4 12.6 2.9 12.4 

Southeast 22843 2.3 12.3 2.6 12.2 

Central U.S. 16541 -4.8 13.2 -4.4 13.4 

West 35445 -0.2 13.5 -0.3 13.5 

17 
 

 

 

3. Hazardous air pollutants 

An operational model performance evaluation for daily, monthly, seasonal, and annual 

specific air toxics (formaldehyde, acetaldehyde, benzene, acrolein, and 1,3-butadiene) was 

conducted in order to estimate the ability of the CMAQ modeling system to replicate the base 

year concentrations for the 12-km Eastern and Western United States domains. Toxic 

measurements from 471 sites in the East and 135 sites in the West were included in the 

evaluation and were taken from the 2005 State/local monitoring site data in the National Air 

Toxics Trends Stations (NATTS). Similar to PM2.5 and ozone, the evaluation principally 

consists of statistical assessments of model versus observed pairs that were paired in time and 

space on daily basis. Appendix B contains a more detailed summary of air toxics model 

performance over the 12km Eastern and Western U.S. grid. A summary of the evaluation is 

presented here. 

Model predictions of annual formaldehyde, acetaldehyde and benzene showed relatively 

small bias and error percentages when compared to observations. The model yielded larger bias 

and error results for 1,3 butadiene and acrolein based on limited monitoring sites. As with the 

national, annual PM2.5 and ozone CMAQ modeling, the “acceptability” of model performance 

was judged by comparing our CMAQ 2005 performance results to the limited performance 

found in recent regional multi-pollutant model applications.27,28,29 Overall, the normalized mean 

bias and error (NMB and NME), as well as the fractional bias and error (FB and FE) statistics 

shown in Table II-7 indicate that CMAQ-predicted 2005 toxics (i.e., observation vs. model 

predictions) are within the range of recent regional modeling applications. 

27 Phillips, S., K. Wang, C. Jang, N. Possiel, M. Strum, T. Fox, 2007: Evaluation of 2002 Multi-pollutant Platform: 

Air Toxics, Ozone, and Particulate Matter, 7th Annual CMAS Conference, Chapel Hill, NC, October 6-8, 2008. 

28 Strum, M., Wesson, K., Phillips, S., Cook, R., Michaels, H., Brzezinski, D., Pollack, A., Jimenez, M., Shepard, S. 

Impact of using lin-level emissions on multi-pollutant air quality model predictions at regional and local scales. 17th 

Annual International Emission Inventory Conference, Portland, Oregon , June 2-5, 2008. 

29 Wesson, K., N. Fann, and B. Timin, 2010: Draft Manuscript: Air Quality and Benefits Model Responsiveness to 

Varying Horizontal Resolution in the Detroit Urban Area, Atmospheric Pollution Research, Special Issue: Air 

Quality Modeling and Analysis. 

18 
 

 

Table II-7. 2005 CMAQ annual toxics model performance statistics 

CMAQ 2005 Annual No. of Obs. NMB (%) NME (%) FB (%) FE (%) 

Formaldehyde 

Acetaldehyde 

12-km EUS 6365 -55.5 65.3 -39.2 65.6 

12-km WUS 1928 -28.4 52.1 -30.1 60.7 

Midwest 771 -77.1 85.4 -25.8 74.0 

Northeast 1982 -30.5 51.3 -28.5 61.6 

Southeast 1246 -66.2 72.2 -51.3 70.4 

Central U.S. 1815 -43.5 51.0 -41.4 61.5 

West 1746 -25.5 52.3 -26.0 59.8 

12-km EUS 6094 -4.2 62.0 -8.2 60.3 

12-km WUS 1892 -19.2 53.7 -19.5 59.6 

Midwest 703 -12.6 58.0 -12.1 60.0 

Northeast 1969 -9.5 62.8 -9.0 63.7 

Southeast 1231 0.4 63.5 -6.2 62.2 

Central U.S. 1640 1.8 57.0 -4.3 51.1 

West 1709 -20.4 54.1 -20.1 60.6 

Benzene 

12-km EUS 11615 -32.6 66.8 -13.5 62.8 

12-km WUS 3369 -38.4 60.8 -30.4 63.9 

Midwest 1425 -8.3 72.7 25.2 62.4 

Northeast 2589 21.6 53.3 18.1 46.8 

Southeast 2426 -41.1 68.6 -17.2 59.8 

Central U.S. 4737 -47.0 68.3 -32.7 69.4 

West 2333 -30.5 61.2 -19.2 63.4 

1,3-Butadiene 

12-km EUS 8102 -74.7 85.6 -49.4 91.6 

12-km WUS 1976 -51.9 82.1 -34.5 91.7 

Midwest 516 -78.7 86.2 -48.3 81.9 

Northeast 1902 -41.6 55.5 -54.8 71.3 

Southeast 1226 -85.4 86.4 -106.2 111.5 

Central U.S. 4142 -66.5 85.9 -20.0 89.2 

West 1082 -40.8 77.5 -41.9 85.3 

Acrolein 

12-km EUS 1660 -94.4 95.0 -131.3 142.2 

12-km WUS 783 -95.7 95.7 -168.1 170.4 

Midwest n/a n/a n/a n/a n/a 

Northeast 850 -90.4 91.5 -120.5 134.2 

Southeast 278 -97.0 97.0 -156.4 157.0 

Central U.S. n/a n/a n/a n/a n/a 

West 592 -95.9 95.9 -177.6 177.6 

III. CMAQ Model Results 

A. Impacts of RFS2 Changes on Future PM2.5 Levels 

It is important to remember that there are uncertainties and limitations related to the air 

quality modeling (see Section 3.4.1.3 in RFS2 RIA), including the projected amount of E85 in 

19 
 

 

 

 

 

use. The modeled projected usage of E85 is higher than what was included in the final rule 

inventory, which could overestimate the decreases in PM2.5. These differences in the air quality 

modeling inventories and the final rule inventories are discussed in detail in Section 3.3 of the 

RFS2 RIA. 

After the air quality modeling was complete an error was found in the PM inventory for 

locomotives, therefore only design value changes over all 577 modeled counties are reported. A 

large majority of the modeled counties will have relatively minor annual average PM2.5 design 

value changes of between -0.05 μg/m3

 and +0.05 μg/m3. On a population-weighted basis, the 

average modeled future-year annual PM2.5 design values are projected to decrease by 0.002 

μg/m3 when compared with the RFS1 mandate or AEO reference case.30 Likewise, daily PM2.5 

design values show the majority of the modeled counties will experience changes of between ­

0.25 μg/m3 and +0.25 μg/m3. On a population-weighted basis, the average modeled future-year 

daily PM2.5 design value is projected to decrease by 0.06 μg/m3

 when compared with the RFS1 

mandate scenario or 0.05 μg/m3

 when compared with the AEO scenario. 

The changes in ambient PM2.5 described above are likely due to both increased emissions 

at biofuel production plants and from biofuel transport, and reductions in SOA formation and 

reduced emissions from gasoline refineries. In addition, decreases in ambient PM are predicted 

because our modeling inventory assumed large volumes of E85 use and also that E85 usage 

reduces PM tailpipe emissions. As mentioned previously and in more detail in Section 3.4 of the 

RIA, these direct PM emission reductions would not occur with final rule inventory assumptions. 

B. Impacts of RFS2 Changes on Future 8-Hour Ozone Levels 

This section summarizes the results of our modeling of ozone air quality impacts in the 

future due to the required renewable fuel volumes. Our modeling indicates that the renewable 

fuel standards will result in increases in ozone design value concentrations in many areas of the 

country as well as decreases in ozone design value concentrations in a small number of areas. 

Figures III-1 and III-2 display the projected county-level, 8-hour ozone design value changes 

expected when the RFS2 control scenario is compared to the RFS1 mandate reference case and 

the AEO 2007 reference case respectively.31 The air quality modeling of the expected impacts of 

the final rule shows that in 2022, most counties with modeled data, especially those in the 

southeast U.S., will see increases in their ozone design values. The bulk of these design value 

increases are less than 0.5 ppb. On a population-weighted basis, the average modeled futureyear 8-hour ozone design values are projected to increase by 0.15 ppb in 2022 when compared 

with the RFS1 mandate reference case and increase by 0.27 ppb when comparing with the AEO 

reference case. On a population-weighted basis those counties that are projected to be above the 

30 Note that the change in annual average PM2.5 for design values differs from the change in national populationweighted annual average PM2.5 discussed in Sections I and VIII of the preamble and Chapter 5 of the RIA. The 

discussion of national population-weighted annual average PM2.5 with respect to health impacts in Sections I and 

VIII of the preamble and Chapter 5 of this RIA is based on modeling data from all grid cells rather than just those 

counties with monitors. It finds that there is a small increase in annual average PM2.5. 31 The air quality modeling used a different speciation profile for E10 gasoline headspace emissions in the RFS2 

control case than was used for the RFS1 and AEO reference cases. This inconsistency is described in Section 3.4.1.3 

in the RFS2 RIA. 

20 
 

2008 ozone standard in 2022 will see decreases of 0.18 when compared with the AEO reference 

case and 0.17 ppb when compared with the RFS1 mandate reference case. 

When comparing the changes in projected ozone it is important to note the differences in 

the inventories used for the air quality modeling and the inventories presented in the RFS2 final 

rule. The most important difference and uncertainty has to do with the fact that the modeled 

inventory assumes increases in NOx for vehicles using E10 fuel. The air quality modeling 

indicates that the NOx increases required from the renewable fuel volumes contribute to the 

ozone increases in NOx-limited areas as well as the ozone decreases in VOC-limited areas. 

Figure III-1. Model-projected change in annual 8-hour Ozone design values between the 

RFS2 Control Scenario and the RFS1 Mandate Scenario in 2022. Units are ppb. 

21 
 

 

 

 

 

Figure III-2. Model-projected change in annual 8-hour Ozone design values between the 

RFS2 Control Scenario and AEO Scenario in 2022. Units are ppb. 

C. Impacts of RFS2 Changes on Toxic Air Pollutant Levels 

This section summarizes the results of our modeling of ambient air toxics impacts in the 

future from the renewable fuel volumes required by RFS2. Specifically, we compare the RFS1 

mandate and AEO reference scenarios to the RFS2 control scenario for 2022 (see Section 3.3 of 

the RIA for more information on the scenarios).32 Our modeling indicates that, while there are 

some localized impacts, the renewable fuel volumes required by RFS2 have relatively little 

impact on national average ambient concentrations of the modeled air toxics. An exception is 

increased ambient concentrations of ethanol. Since the overall impacts are relatively small, we 

concluded that assessing exposure to ambient concentrations and conducting a quantitative risk 

assessment of air toxic impacts was not warranted. Although, we developed population metrics, 

including the population living in areas with increases or decreases in concentrations of various 

magnitudes. We also estimated aggregated populations above and below reference 

concentrations for noncancer effects. 

32 We used a different speciation profile for E10 gasoline headspace emissions in the RFS2 control case than was 

used for the RFS1 and AEO reference cases. This inconsistency is described in Section 3.4.1.3 of the RIA. 

22 
 

1. Acetaldehyde 

Overall, the air quality modeling does not show substantial nationwide impacts on 

ambient concentrations of acetaldehyde due to the renewable fuel volumes required by this rule. 

Figure III-3 shows the annual percent changes in ambient concentrations of acetaldehyde are less 

than 1% for most of the country. Several urban areas show decreases in ambient acetaldehyde 

concentrations ranging from 1 to 10%, and some rural areas associated with new ethanol plants 

show increases in ambient acetaldehyde concentrations ranging from 1 to 10% with RFS2. In 

Figure III-4, the annual absolute changes in ambient concentrations of acetaldehyde are generally 

less than 0.1 μg/m3. As noted above, the results show that the largest increases in ambient 

acetaldehyde concentrations with RFS2 volumes occur in areas associated with new ethanol 

plants. This result is due to an increase in emissions of primary acetaldehyde and precursor 

emissions from ethanol plants not included in the RFS1 mandate reference scenario. 

Figure III-3. Acetaldehyde Annual Percent Change in Concentration Between the RFS2 

Mandate Reference Case and the RFS2 Control Case in 2022 

23 
 

 

Figure III-4. Acetaldehyde Annual Absolute Changes in Ambient Concentrations Between 

the RFS1 Mandate Reference Case and the RFS2 Control Case in 2022 (μg/m3) 

Figures III-5 and III-6 show the comparison of the RFS1 mandate reference case with the 

RFS2 control case for summer and winter shows decreases in ambient acetaldehyde 

concentrations in urban areas. Decreases are less pronounced in winter when there is less 

secondary formation of acetaldehyde (Figures III-6). As stated above, the main reason for the 

decrease in urban areas is reductions in certain acetaldehyde precursors, primarily alkenes 

(olefins) that are related to the differences in the E0 gasoline headspace speciation profiles used 

for the control case and the reference cases. While the air quality modeling results presented 

here and in the RFS2 RIA suggest impacts of increased renewable fuel use on ambient 

acetaldehyde are not substantial and there may be decreases in urban areas, there is considerable 

uncertainty associated with these results. Thus, if the reference cases were rerun with revised E0 

headspace profiles, some of the observed decreases could become increases. Additional research 

is underway to address these uncertainties, e.g., measurement of representative fuels to create 

better headspace speciation profiles (Section 3.4.1.3 in the RFS2 RIA) and improvements in 

other speciation profiles based on additional results from the EPAct emissions test program.33 

33. EPAct Phase I II, and III Testing: Comprehensive Gasoline Light-Duty Exhaust Fuel Effects Test Program to 

Cover Multiple Fuel Properties. EPA Contract: EPC-07-028EPA. Southwest Research Institute, San Antonio, TX. 

Phase III of the EPAct emission test program is scheduled for completion in 2010. 

24 
 

Figure III-5. Summer Changes in Acetaldehyde Ambient Concentrations Between the 

RFS1 Mandate Reference Case and the RFS2 Control Case in 2022: (a) Percent Changes 

and (b) Absolute Changes (μg/m3) 

a b 

Figure III-6. Winter Changes in Acetaldehyde Ambient Concentrations Between the RFS1 

Mandate Reference Case and the RFS2 Control Case in 2022: (a) Percent Changes and (b) 

Absolute Changes (μg/m3) 

a b 

2. Formaldehyde 

Our air quality modeling results do not show substantial impacts on ambient 

concentrations of formaldehyde from the renewable fuel volumes required by this rule. As 

25 
 

shown in Figure III-7, most of the U.S. experiences a 1% or less change in ambient 

formaldehyde concentrations. Decreases in ambient formaldehyde concentrations range between 

1 and 5% in a few urban areas. Increases range between 1 and 2.5% in some rural areas 

associated with new ethanol plants; this result is due to increases in emissions of primary 

formaldehyde and formaldehyde precursors from the new ethanol plants. Figure III-8 shows that 

absolute changes in ambient concentrations of formaldehyde are generally less than 0.1 μg/m3. 

Figure III-7. Formaldehyde Annual Percent Change in Concentration Between the RFS1 

Mandate Reference Case and the RFS2 Control Case in 2022 

26 
 

Figure III-8. Formaldehyde Annual Percent Changes in Ambient Concentrations Between 

the RFS1 Mandate Reference Case and the RFS2 Control Case in 2022 (μg/m3) 

3. Ethanol 

Our modeling projects that the renewable fuel volumes required by this rule will lead to 

significant nationwide increases in ambient ethanol concentrations. Figure III-9 shows increases 

ranging between 10 to 50% that are seen across most of the country. The largest increases (more 

than 100%) occur in urban areas with high amounts of onroad emissions and in rural areas 

associated with new ethanol plants. Absolute increases in ambient ethanol concentrations are 

above 1.0 ppb in some urban areas (Figure III-10). The location of these localized increases is 

limited by uncertainties in the placement of the new ethanol plants, as discussed in Section 

3.4.1.3 of the RFS2 RIA. It should be noted here that these increases are overestimated because 

the speciated profile combination used for modeling nonroad emissions was misapplied. While 

sensitivity analyses suggest that the impact of this error was negligible for other pollutants, it 

resulted in overestimates of ethanol impacts by more than 10% across much of the modeling 

domain. Details on the ethanol impacts are discussed in the emissions modeling TSD, found in 

the docket for this rule (EPA-HQ-OAR-2005-0161). 

27 
 

Figure III-9. Ethanol Annual Percent Changes Change in Concentration Between the 

RFS1 Mandate Reference Case and the RFS2 Control Case in 2022 

Figure III-10. Ethanol Annual Absolute Changes in Ambient Concentrations Between the 

RFS1 Mandate Reference Case and the RFS2 Control Case in 2022 (ppb) 

28 
 

4. Benzene 

Our modeling projects that the renewable fuel volumes required by this rule will lead to 

small nationwide decreases in ambient benzene concentrations. Figure III-11, show decreases in 

ambient benzene concentrations that range between 1 and 10% across most of the country and 

can be higher in a few urban areas. Figure III-12 indicates absolute changes in ambient 

concentrations of benzene show reductions up to 0.2 μg/m3. 

Figure III-11. Benzene Annual Percent Change in Concentration Between the RFS1 

Mandate Reference Case and the RFS2 Control Case in 2022 

29 
 

Figure III-12. Benzene Annual Absolute Changes in Ambient Concentrations Between the 

RFS1 Mandate Reference Case and the RFS2 Control Case in 2022 (μg/m3) 

5. 1,3-Butadiene 

The results of our air quality modeling show small increases and decreases in ambient 

concentrations of 1,3-butadiene in parts of the U.S. as a result of the renewable fuel volumes 

required this rule. Overall, as seen in Figure III-13, decreases occur in some southern areas of 

the country and increases occur in some northern areas and areas with high altitudes. Percent 

changes in 1,3-butadiene concentrations are over 50% in several areas; but the changes in 

absolute concentrations of ambient 1,3-butadiene are generally less than 0.005 μg/m3 (Figure III14). Annual increases in ambient concentrations of 1,3-butadiene are driven by wintertime 

rather than summertime changes (Figures III-15 and III-16). These increases appear in rural 

areas with cold winters and low ambient levels but high contributions of emissions from 

snowmobiles, and a major reason for this modeled increase may be deficiencies in available 

emissions test data used to estimate snowmobile 1,3-butadiene emission inventories. These data 

were based on tests using only three engines, which showed significantly higher 1,3-butadiene 

emissions with 10% ethanol. However, they may not have been representative of real-world 

response of snowmobile engines to ethanol. 

30 
 

Figure III-13. 1,3-Butadiene Annual Percent Change in Concentration Between the RFS1 

Mandate Reference Case and the RFS2 Control Case in 2022 

Figure III-14. 1,3-Butadiene Annual Absolute Changes in Ambient Concentrations 

Between the RFS1 Mandate Reference Case and the RFS2 Control Case in 2022 (μg/m3) 

31 
 

Figure III-15. Summer Changes in 1,3-Butadiene Ambient Concentrations Between the 

RFS1 Mandate Reference Case and the RFS2 Control Case in 2022: (a) Percent Changes 

and (b) Absolute Changes (μg/m3) 

a b 

Figure III-16. Winter Changes in 1,3-Butadiene Ambient Concentrations Between the 

RFS1 Mandate Reference Case and the RFS2 Control Case in 2022: (a) Percent Changes 

and (b) Absolute Changes (μg/m3) 

a b 

32 
 

6. Acrolein 

Our air quality modeling shows small regional increases and decreases in ambient 

concentrations of acrolein as a result of the renewable fuel volumes required by this rule. As 

shown in Figure III-17, decreases in acrolein concentrations occur in some eastern and southern 

parts of the U.S. and increases occur in some northern areas and areas associated with new 

ethanol plants. Figure III-18 indicates that changes in absolute ambient concentrations of 

acrolein are between ± 0.001 μg/m3 with the exception of the increases associated with new 

ethanol plants. These increases can be up to and above 0.005 μg/m3 with percent changes above 

50% and are due to increases in emissions of acrolein from the new plants. As discussed in 

Section 3.4.1.3 of the RFS RIA, uncertainties in the placement of new ethanol plants limit the 

model’s projected location of associated emission increases. Ambient acrolein increases in 

upper Michigan, Canada, the Northeast, and the Rocky Mountain region are driven by 

wintertime changes (Figures III-19 and III-20), and occur in the same areas of the country that 

have wintertime rather than summertime increases in ambient 1,3-butadiene. 1,3-butadiene is a 

precursor to acrolein, and these increases are likely associated with the same emission inventory 

issues in areas of high snowmobile usage seen for 1,3-butadiene, as described above. 

Figure III-17. Acrolein Annual Percent Changes Change in Concentration Between the 

RFS1 Mandate Reference Case and the RFS2 Control Case in 2022 

33 
 

Figure III-18. Acrolein Annual Absolute Changes in Ambient Concentrations Between the 

RFS1 Mandate Reference Case and the RFS2 Control Case in 2022 (μg/m3) 

Figure III-19. Summer Changes in Acrolein Ambient Concentrations Between the RFS1 

Mandate Reference Case and the RFS2 Control Case in 2022: (a) Percent Changes and (b) 

Absolute Changes (μg/m3) 

a b 

34 
 

Figure III-20. Winter Changes in Acrolein Ambient Concentrations Between the RFS1 

Mandate Reference Case and the RFS2 Control Case in 2022: (a) Percent Changes and (b) 

Absolute Changes (μg/m3) 

a b 

35 
 

Appendix A: 8-Hour Ozone Design Values for RFS-2 Scenarios (units are 

ppb) 

State Name County Name Baseline DV 2022 RFS1 

DV 

2022 AEO 

DV 

2022 RFS2 

DV 

Alabama Baldwin 77.30 63.76 64.20 64.40 

Alabama Clay 74.00 56.43 56.65 56.88 

Alabama Colbert 72.00 50.47 50.77 51.00 

Alabama Elmore 70.70 52.07 52.38 52.63 

Alabama Etowah 71.70 54.66 54.92 55.14 

Alabama Houston 71.00 57.36 57.55 57.82 

Alabama Jefferson 83.70 62.27 62.55 62.73 

Alabama Lawrence 72.00 55.16 55.40 56.02 

Alabama Madison 77.30 59.03 59.39 59.81 

Alabama Mobile 76.70 63.66 64.07 64.24 

Alabama Montgomery 69.30 49.96 50.26 50.51 

Alabama Morgan 77.30 62.50 62.80 64.07 

Alabama Russell 71.30 55.24 55.47 56.26 

Alabama Shelby 85.70 63.20 63.50 63.65 

Alabama Sumter 64.00 53.65 53.78 54.02 

Alabama Talladega 72.00 52.98 53.18 53.40 

Alabama Tuscaloosa 73.30 53.52 53.74 53.93 

Arizona Cochise 71.30 62.66 62.74 62.74 

Arizona Coconino 73.00 64.74 64.77 64.80 

Arizona Gila 80.30 62.93 63.10 63.10 

Arizona La Paz 72.00 62.13 62.17 62.20 

Arizona Maricopa 83.00 68.91 69.06 68.99 

Arizona Pima 76.00 63.54 63.67 63.67 

Arizona Pinal 79.30 62.93 63.10 63.08 

Arizona Yavapai 72.00 62.68 62.74 62.77 

Arizona Yuma 75.00 63.11 63.18 63.19 

Arkansas Crittenden 87.30 66.66 66.84 67.01 

Arkansas Newton 72.70 58.70 58.90 59.46 

Arkansas Polk 75.00 62.86 63.01 63.44 

Arkansas Pulaski 79.70 59.98 60.21 60.65 

California Alameda 78.30 70.90 70.90 70.89 

California Amador 83.00 71.11 71.11 71.21 

California Butte 83.70 69.84 69.85 70.39 

California Calaveras 91.30 80.22 80.23 80.36 

California Colusa 67.00 57.77 57.77 57.96 

California Contra Costa 73.30 69.50 69.50 69.49 

California El Dorado 96.00 79.46 79.47 79.51 

California Fresno 98.30 86.26 86.29 86.37 

California Glenn 65.50 56.24 56.24 56.44 

California Imperial 85.00 74.04 74.05 74.04 

California Inyo 82.30 71.67 71.72 71.76 

California Kern 110.00 98.45 98.49 98.47 

California Kings 85.70 73.42 73.46 73.55 

California Lake 60.70 53.07 53.08 53.16 

California Los Angeles 114.00 103.39 103.39 103.23 

California Madera 79.30 68.48 68.51 68.61 

36 
 

California Marin 49.70 45.74 45.74 45.69 

California Mariposa 86.30 75.74 75.77 75.88 

California Mendocino 56.70 48.97 48.99 49.03 

California Merced 89.30 76.57 76.63 76.82 

California Monterey 61.00 54.77 54.77 54.80 

California Napa 59.30 52.18 52.20 52.23 

California Nevada 96.30 80.00 80.01 80.06 

California Orange 84.30 81.40 81.35 80.83 

California Placer 94.00 78.00 78.01 78.05 

California Riverside 112.30 108.72 108.66 108.06 

California Sacramento 97.30 81.05 81.05 81.09 

California San Benito 75.00 65.39 65.40 65.46 

California San Bernardino 123.30 121.22 121.17 120.64 

California San Diego 87.70 76.76 76.75 76.66 

California San Francisco 46.00 45.37 45.37 45.34 

California San Joaquin 75.30 67.86 67.91 68.00 

California San Luis Obispo 70.70 62.46 62.48 62.56 

California San Mateo 53.70 51.43 51.42 51.39 

California Santa Barbara 76.00 68.26 68.27 68.27 

California Santa Clara 75.30 65.26 65.26 65.25 

California Santa Cruz 61.30 55.65 55.64 55.60 

California Shasta 79.30 67.23 67.25 67.45 

California Siskiyou 63.50 54.67 54.72 54.93 

California Solano 72.70 63.93 63.94 63.98 

California Sonoma 47.70 41.27 41.28 41.32 

California Stanislaus 84.70 74.98 75.05 75.21 

California Sutter 82.00 70.06 70.06 70.20 

California Tehama 82.70 70.26 70.28 70.58 

California Tulare 103.70 89.07 89.34 89.41 

California Tuolumne 80.00 70.43 70.44 70.56 

California Ventura 89.70 78.66 78.68 78.65 

California Yolo 78.70 67.63 67.64 67.67 

Colorado Adams 69.00 62.90 62.99 62.91 

Colorado Arapahoe 78.70 69.39 69.52 69.51 

Colorado Boulder 77.00 67.41 67.52 67.51 

Colorado Denver 73.00 66.55 66.64 66.56 

Colorado Douglas 83.00 73.88 73.99 73.93 

Colorado El Paso 73.30 64.60 64.71 64.74 

Colorado Jefferson 81.70 74.36 74.44 74.33 

Colorado La Plata 63.70 59.00 59.04 59.06 

Colorado Larimer 76.00 66.07 66.19 66.20 

Colorado Montezuma 72.00 66.07 66.12 66.15 

Colorado Weld 76.70 67.37 67.49 67.52 

Connecticut Fairfield 92.30 78.29 78.30 78.22 

Connecticut Hartford 84.30 67.41 67.50 67.67 

Connecticut Litchfield 87.70 70.05 70.15 70.35 

Connecticut Middlesex 90.30 75.10 75.15 75.24 

Connecticut New Haven 90.30 76.14 76.17 76.16 

Connecticut New London 85.30 70.51 70.54 70.50 

Connecticut Tolland 88.70 71.08 71.16 71.33 

Delaware Kent 80.30 64.51 64.59 64.71 

Delaware New Castle 82.30 68.12 68.18 68.27 

Delaware Sussex 82.70 69.10 69.16 69.25 

37 
 

D.C. Washington 84.70 68.78 68.87 69.00 

Florida Alachua 72.00 54.16 54.45 54.67 

Florida Baker 68.70 53.65 53.90 54.11 

Florida Bay 78.70 61.49 61.98 62.23 

Florida Brevard 71.30 57.01 57.34 57.38 

Florida Broward 65.00 58.55 58.56 58.63 

Florida Collier 68.30 53.82 54.19 54.28 

Florida Columbia 72.00 56.97 57.20 57.41 

Florida Duval 77.70 62.74 63.05 63.06 

Florida Escambia 82.70 67.06 67.72 67.86 

Florida Highlands 72.30 60.69 60.89 61.15 

Florida Hillsborough 80.70 64.92 65.19 65.16 

Florida Holmes 70.30 56.17 56.39 56.67 

Florida Lake 76.70 59.32 59.76 59.80 

Florida Lee 70.30 55.56 56.30 56.37 

Florida Leon 71.00 53.22 53.59 53.90 

Florida Manatee 77.30 60.49 60.76 60.80 

Florida Marion 73.00 55.13 55.46 55.60 

Florida Miami-Dade 71.30 65.33 65.38 65.39 

Florida Orange 79.30 62.40 62.87 62.89 

Florida Osceola 72.00 53.73 54.18 54.24 

Florida Palm Beach 65.00 57.86 57.97 58.28 

Florida Pasco 76.30 59.87 60.19 60.23 

Florida Pinellas 72.70 56.09 56.39 56.44 

Florida Polk 74.70 57.85 58.14 58.13 

Florida St Lucie 66.50 54.79 55.10 55.25 

Florida Santa Rosa 80.00 65.21 66.25 66.45 

Florida Sarasota 77.30 58.88 59.19 59.24 

Florida Seminole 76.00 59.45 59.90 59.91 

Florida Volusia 68.30 51.74 52.04 52.18 

Florida Wakulla 71.30 57.05 57.40 57.69 

Georgia Bibb 81.00 65.09 65.36 65.55 

Georgia Chatham 68.30 57.09 57.38 57.71 

Georgia Chattooga 75.00 55.41 55.70 55.92 

Georgia Clarke 80.70 56.49 56.90 57.15 

Georgia Cobb 82.70 59.53 59.97 60.18 

Georgia Columbia 73.00 56.28 56.50 57.48 

Georgia Coweta 82.00 64.12 64.36 64.57 

Georgia Dawson 76.30 52.93 53.38 53.62 

Georgia De Kalb 88.70 70.62 70.88 71.01 

Georgia Douglas 87.30 63.96 64.29 64.51 

Georgia Fayette 85.70 66.46 66.73 66.90 

Georgia Fulton 91.70 73.01 73.28 73.42 

Georgia Glynn 67.00 52.25 52.53 53.63 

Georgia Gwinnett 88.70 65.80 66.20 66.38 

Georgia Henry 89.70 66.91 67.26 67.45 

Georgia Murray 78.00 60.28 60.54 60.88 

Georgia Muscogee 75.70 56.81 57.09 58.02 

Georgia Paulding 80.30 56.54 56.86 57.06 

Georgia Richmond 80.30 60.76 61.00 62.18 

Georgia Rockdale 90.00 65.63 65.99 66.18 

Georgia Sumter 72.30 57.41 57.61 57.88 

Idaho Ada 76.00 69.69 69.81 69.80 

38 
 

Idaho Canyon 66.00 59.37 59.53 59.54 

Idaho Elmore 63.00 57.30 57.42 57.44 

Idaho Kootenai 67.00 57.90 58.14 58.20 

Illinois Adams 70.00 58.60 58.74 59.40 

Illinois Champaign 68.30 56.65 56.79 57.92 

Illinois Clark 66.00 54.50 54.65 55.15 

Illinois Cook 77.70 69.45 69.59 69.84 

Illinois Du Page 69.00 62.49 62.60 62.89 

Illinois Effingham 70.00 57.72 57.88 58.43 

Illinois Hamilton 73.00 58.96 59.13 59.74 

Illinois Jersey 78.70 60.58 60.69 61.37 

Illinois Kane 74.30 63.36 63.48 63.87 

Illinois Lake 78.00 69.37 69.50 69.76 

Illinois McHenry 73.30 60.54 60.68 61.07 

Illinois McLean 73.00 59.13 59.32 60.09 

Illinois Macon 71.30 58.95 59.09 59.82 

Illinois Macoupin 73.00 55.79 55.89 56.46 

Illinois Madison 83.00 67.06 67.18 67.76 

Illinois Peoria 72.70 61.99 62.11 62.76 

Illinois Randolph 72.00 60.39 60.54 61.28 

Illinois Rock Island 65.30 55.10 55.22 55.90 

Illinois St Clair 81.70 66.77 66.90 67.49 

Illinois Sangamon 70.00 55.21 55.34 55.91 

Illinois Will 71.70 60.94 61.07 61.47 

Illinois Winnebago 69.00 57.39 57.55 58.31 

Indiana Allen 79.30 63.96 64.25 65.09 

Indiana Boone 79.70 63.90 64.06 64.52 

Indiana Carroll 74.00 60.27 60.47 61.28 

Indiana Clark 80.30 63.04 63.19 63.33 

Indiana Delaware 76.30 60.84 61.15 61.86 

Indiana Elkhart 79.00 64.27 64.54 65.34 

Indiana Floyd 77.70 63.61 63.75 63.84 

Indiana Greene 78.30 62.41 62.58 63.52 

Indiana Hamilton 82.70 65.75 65.95 66.52 

Indiana Hancock 78.00 62.44 62.63 63.17 

Indiana Hendricks 75.30 61.36 61.51 61.85 

Indiana Huntington 75.00 61.28 61.55 62.17 

Indiana Jackson 74.70 60.27 60.42 61.17 

Indiana Johnson 76.70 63.38 63.53 63.98 

Indiana Lake 81.00 72.55 72.76 73.17 

Indiana La Porte 78.50 67.43 67.61 68.08 

Indiana Madison 76.70 60.45 60.66 61.36 

Indiana Marion 78.70 64.00 64.16 64.66 

Indiana Morgan 77.00 63.02 63.21 63.81 

Indiana Perry 81.00 63.99 64.18 64.53 

Indiana Porter 78.30 69.47 69.70 70.09 

Indiana Posey 71.70 57.31 57.46 58.66 

Indiana St Joseph 79.30 64.84 65.09 65.83 

Indiana Shelby 77.30 64.89 65.06 65.69 

Indiana Vanderburgh 77.30 62.01 62.16 63.11 

Indiana Vigo 74.00 61.42 61.67 62.23 

Indiana Warrick 77.70 63.17 63.32 63.80 

Iowa Bremer 66.30 56.49 56.71 57.58 

39 
 

Iowa Clinton 71.30 60.46 60.61 61.37 

Iowa Harrison 74.70 63.57 63.71 64.42 

Iowa Linn 68.30 58.14 58.60 59.40 

Iowa Montgomery 65.70 55.56 55.71 56.26 

Iowa Palo Alto 61.00 52.63 52.80 53.94 

Iowa Polk 63.00 51.30 51.45 52.21 

Iowa Scott 72.00 60.00 60.15 60.88 

Iowa Story 61.00 49.97 50.12 50.99 

Iowa Van Buren 69.00 58.37 58.53 59.31 

Iowa Warren 64.50 52.00 52.19 53.03 

Kansas Douglas 73.00 59.93 60.12 60.58 

Kansas Johnson 75.30 62.36 62.53 62.96 

Kansas Leavenworth 75.00 63.88 64.02 64.28 

Kansas Linn 73.30 59.50 59.72 60.28 

Kansas Sedgwick 71.30 59.33 59.51 60.09 

Kansas Sumner 71.70 59.82 60.01 60.51 

Kansas Trego 70.70 63.18 63.33 63.58 

Kansas Wyandotte 75.30 64.35 64.48 64.68 

Kentucky Bell 71.70 53.68 53.94 54.25 

Kentucky Boone 75.70 60.67 60.79 60.97 

Kentucky Boyd 77.30 63.49 63.61 63.74 

Kentucky Bullitt 74.00 59.93 60.07 60.21 

Kentucky Campbell 75.00 62.36 62.52 62.78 

Kentucky Carter 71.00 56.67 56.80 56.96 

Kentucky Christian 78.00 60.18 60.35 60.57 

Kentucky Daviess 75.70 61.46 61.63 61.98 

Kentucky Edmonson 73.70 59.28 59.44 59.79 

Kentucky Fayette 70.30 57.37 57.53 57.72 

Kentucky Greenup 76.70 63.26 63.38 63.53 

Kentucky Hancock 74.00 58.82 58.98 59.29 

Kentucky Hardin 74.70 60.02 60.16 60.39 

Kentucky Henderson 75.30 61.35 61.49 61.94 

Kentucky Jefferson 78.30 64.51 64.65 64.77 

Kentucky Jessamine 73.30 59.35 59.50 59.75 

Kentucky Kenton 78.70 63.53 63.72 64.01 

Kentucky Livingston 73.70 61.16 61.38 61.66 

Kentucky McCracken 73.30 61.71 61.89 62.20 

Kentucky McLean 73.00 58.86 59.01 59.46 

Kentucky Oldham 83.00 63.73 63.89 64.08 

Kentucky Perry 72.30 58.50 58.66 58.97 

Kentucky Pike 66.70 53.76 53.91 54.13 

Kentucky Pulaski 70.30 58.12 58.26 58.48 

Kentucky Simpson 75.70 58.21 58.36 58.76 

Kentucky Trigg 70.00 55.17 56.03 56.36 

Kentucky Warren 72.00 58.85 58.98 59.24 

Louisiana Ascension 82.00 72.39 72.47 72.71 

Louisiana Beauregard 75.00 67.63 67.70 67.92 

Louisiana Bossier 78.00 62.91 63.20 63.40 

Louisiana Caddo 79.00 63.73 63.99 64.31 

Louisiana Calcasieu 82.00 72.48 72.63 72.96 

Louisiana East Baton Rouge 92.00 81.32 81.44 81.71 

Louisiana Grant 73.00 61.93 62.09 62.47 

Louisiana Iberville 85.00 75.62 75.70 75.87 

40 
 

Louisiana Jefferson 83.00 72.83 73.15 73.25 

Louisiana Lafayette 82.00 70.27 70.41 70.81 

Louisiana Lafourche 79.30 70.35 70.47 70.58 

Louisiana Livingston 78.30 69.46 69.54 69.76 

Louisiana Orleans 70.00 61.82 62.06 62.13 

Louisiana Ouachita 75.30 62.20 62.44 62.68 

Louisiana Pointe Coupee 83.70 74.74 74.80 75.10 

Louisiana St Bernard 78.00 67.71 67.96 68.09 

Louisiana St Charles 77.30 67.58 67.93 68.01 

Louisiana St James 76.30 67.78 67.88 68.00 

Louisiana St John The Baptis 79.00 69.83 70.00 70.13 

Louisiana St Mary 76.00 66.29 66.42 66.59 

Louisiana West Baton Rouge 84.30 74.24 74.34 74.60 

Maine Cumberland 72.00 58.25 58.28 58.36 

Maine Hancock 82.00 67.38 67.53 67.68 

Maine Kennebec 69.70 56.68 56.75 56.85 

Maine Knox 75.30 61.11 61.18 61.29 

Maine Oxford 61.00 51.06 51.18 51.48 

Maine Penobscot 67.00 56.74 56.83 56.96 

Maine Sagadahoc 68.50 55.72 55.77 55.85 

Maine York 74.00 60.68 60.74 60.80 

Maryland Anne Arundel 89.70 69.53 69.64 69.80 

Maryland Baltimore 85.30 73.83 74.01 74.01 

Maryland Calvert 81.00 63.80 64.07 64.20 

Maryland Carroll 83.30 64.12 64.22 64.37 

Maryland Cecil 90.70 70.33 70.46 70.61 

Maryland Charles 86.00 65.14 65.28 65.49 

Maryland Frederick 80.30 62.78 62.85 62.99 

Maryland Garrett 75.50 60.08 60.25 60.57 

Maryland Harford 92.70 78.87 79.07 79.10 

Maryland Kent 82.00 63.70 63.79 63.91 

Maryland Montgomery 83.00 66.14 66.23 66.33 

Maryland Prince Georges 91.00 71.16 71.27 71.44 

Maryland Washington 78.30 62.37 62.48 62.67 

Massachusetts Barnstable 84.70 69.99 70.07 69.91 

Massachusetts Berkshire 79.70 64.49 64.64 64.92 

Massachusetts Bristol 82.70 69.53 69.58 69.63 

Massachusetts Dukes 83.00 71.26 71.30 71.34 

Massachusetts Essex 83.30 71.29 71.39 71.40 

Massachusetts Hampden 87.30 70.03 70.12 70.29 

Massachusetts Hampshire 85.00 67.67 67.77 67.96 

Massachusetts Middlesex 79.00 63.92 64.01 64.13 

Massachusetts Norfolk 84.70 68.40 68.56 68.42 

Massachusetts Suffolk 80.30 65.30 65.40 65.40 

Massachusetts Worcester 80.00 62.82 62.92 63.15 

Michigan Allegan 90.00 75.26 75.49 76.18 

Michigan Benzie 81.70 68.76 68.99 69.68 

Michigan Berrien 82.30 69.63 69.83 70.33 

Michigan Cass 80.70 66.37 66.63 67.42 

Michigan Clinton 75.70 60.43 60.67 61.16 

Michigan Genesee 79.30 64.31 64.56 65.07 

Michigan Huron 75.70 63.63 63.84 64.30 

Michigan Ingham 76.00 61.87 62.12 62.72 

41 
 

Michigan Kalamazoo 75.30 61.55 61.83 62.79 

Michigan Kent 81.00 65.22 65.50 66.13 

Michigan Leelanau 75.70 63.85 64.33 65.03 

Michigan Lenawee 78.70 64.93 65.19 65.64 

Michigan Macomb 86.00 70.95 71.30 71.69 

Michigan Mason 79.70 65.67 65.86 66.57 

Michigan Missaukee 73.70 60.43 60.67 61.32 

Michigan Muskegon 85.00 71.44 71.61 72.28 

Michigan Oakland 78.00 66.14 66.41 66.84 

Michigan Ottawa 81.70 67.25 67.45 68.07 

Michigan St Clair 82.30 67.67 67.93 68.51 

Michigan Schoolcraft 79.30 65.40 65.53 66.22 

Michigan Washtenaw 78.30 66.16 66.38 66.68 

Michigan Wayne 82.00 69.27 69.51 69.86 

Minnesota Anoka 67.70 63.38 63.50 64.14 

Minnesota St Louis 65.00 55.52 55.67 56.34 

Mississippi Adams 74.70 64.38 64.50 64.82 

Mississippi Bolivar 74.30 60.09 60.28 60.72 

Mississippi De Soto 82.70 65.16 65.32 65.66 

Mississippi Hancock 79.00 66.94 67.23 67.38 

Mississippi Harrison 83.00 68.47 68.70 68.87 

Mississippi Hinds 71.30 51.08 51.42 51.61 

Mississippi Jackson 80.30 67.43 67.67 67.81 

Mississippi Lauderdale 74.30 58.34 58.56 58.91 

Mississippi Lee 73.70 54.53 54.83 55.11 

Missouri Cass 74.70 61.11 61.28 61.72 

Missouri Cedar 75.70 62.38 62.56 63.26 

Missouri Clay 84.30 70.48 70.64 70.89 

Missouri Clinton 83.00 68.47 68.64 68.90 

Missouri Greene 73.00 59.73 59.85 60.34 

Missouri Jefferson 82.30 69.75 69.91 70.74 

Missouri Lincoln 87.00 71.24 71.40 72.26 

Missouri Monroe 71.70 58.85 59.00 59.62 

Missouri Perry 77.50 63.18 63.34 63.85 

Missouri Platte 77.00 65.23 65.37 65.57 

Missouri St Charles 87.00 68.85 68.98 69.82 

Missouri Ste Genevieve 79.70 66.50 66.63 67.22 

Missouri St Louis 88.00 73.02 73.18 74.19 

Missouri St Louis City 84.00 69.19 69.32 69.98 

Montana Yellowstone 59.00 54.67 54.70 54.76 

Nebraska Douglas 68.70 59.73 59.84 60.48 

Nebraska Lancaster 56.00 46.74 46.85 47.41 

Nevada Clark 83.70 74.23 74.33 74.20 

Nevada Washoe 70.70 60.56 60.62 60.67 

Nevada White Pine 72.30 64.93 64.97 65.01 

Nevada Carson City 65.00 55.81 55.82 55.87 

New Hampshire Belknap 71.30 56.01 55.64 55.73 

New Hampshire Cheshire 70.70 56.59 56.65 56.78 

New Hampshire Coos 77.00 63.97 64.14 64.43 

New Hampshire Grafton 67.00 55.17 55.27 55.44 

New Hampshire Hillsborough 78.70 63.46 63.53 63.64 

New Hampshire Merrimack 71.70 56.02 56.07 56.16 

New Hampshire Rockingham 75.00 61.50 61.56 61.62 

42 
 

New Hampshire Sullivan 70.00 57.34 57.43 57.60 

New Jersey Atlantic 79.30 65.49 65.53 65.60 

New Jersey Bergen 86.00 74.46 74.48 74.46 

New Jersey Camden 89.30 72.65 72.73 72.88 

New Jersey Cumberland 83.30 66.32 66.39 66.54 

New Jersey Gloucester 87.00 71.61 71.68 71.78 

New Jersey Hudson 85.70 73.50 73.49 73.47 

New Jersey Hunterdon 89.00 70.25 70.37 70.59 

New Jersey Mercer 88.00 72.37 72.46 72.61 

New Jersey Middlesex 88.30 71.71 71.78 71.91 

New Jersey Monmouth 87.30 74.07 74.07 74.07 

New Jersey Morris 83.30 67.01 67.10 67.26 

New Jersey Ocean 93.00 75.75 75.80 75.92 

New Jersey Passaic 81.00 67.07 67.13 67.24 

New Mexico Bernalillo 73.70 61.89 62.02 62.04 

New Mexico Dona Ana 75.30 68.52 68.58 68.60 

New Mexico Eddy 69.00 64.38 64.44 64.52 

New Mexico Grant 66.00 59.96 60.01 60.03 

New Mexico Lea 69.50 65.30 65.34 65.40 

New Mexico Sandoval 73.30 61.55 61.68 61.70 

New Mexico San Juan 71.30 67.01 67.05 67.06 

New York Albany 73.70 59.59 59.72 59.97 

New York Bronx 74.70 67.68 67.65 67.53 

New York Chautauqua 86.70 73.83 74.02 74.51 

New York Chemung 68.70 57.63 57.75 58.04 

New York Dutchess 75.70 61.25 61.34 61.48 

New York Erie 85.00 70.86 71.07 71.58 

New York Essex 77.00 64.66 64.81 65.23 

New York Hamilton 71.70 60.64 60.77 61.12 

New York Herkimer 68.30 58.08 58.21 58.54 

New York Jefferson 78.00 64.47 64.72 64.90 

New York Madison 72.00 59.75 59.87 60.21 

New York Monroe 75.00 62.57 62.81 63.03 

New York Niagara 82.70 71.53 71.75 71.96 

New York Oneida 68.30 57.13 57.30 57.68 

New York Onondaga 73.70 62.92 63.10 63.43 

New York Orange 82.00 66.60 66.67 66.78 

New York Oswego 78.00 66.62 66.83 67.11 

New York Putnam 84.30 69.71 69.76 69.84 

New York Queens 80.00 69.57 69.56 69.54 

New York Rensselaer 77.30 62.29 62.46 62.73 

New York Richmond 88.30 75.53 75.54 75.54 

New York Saratoga 79.70 64.39 64.56 64.85 

New York Schenectady 70.00 56.91 57.05 57.34 

New York Suffolk 90.30 81.86 81.83 81.77 

New York Ulster 77.30 62.86 62.98 63.25 

New York Wayne 68.00 57.22 57.42 57.64 

New York Westchester 87.70 76.61 76.60 76.49 

North Carolina Alexander 77.00 57.64 57.72 58.15 

North Carolina Avery 70.00 56.78 56.89 57.23 

North Carolina Buncombe 74.00 59.31 59.43 59.81 

North Carolina Caldwell 74.30 54.93 55.00 55.52 

North Carolina Caswell 76.30 58.13 58.22 58.74 

43 
 

North Carolina Chatham 73.30 56.71 56.79 57.21 

North Carolina Cumberland 81.70 61.89 61.96 63.08 

North Carolina Davie 81.30 61.84 61.93 62.45 

North Carolina Durham 77.00 57.26 57.33 57.88 

North Carolina Edgecombe 77.00 58.76 58.84 59.31 

North Carolina Forsyth 80.00 62.34 62.43 63.18 

North Carolina Franklin 78.70 60.04 60.12 60.63 

North Carolina Graham 78.30 61.41 61.64 61.97 

North Carolina Granville 82.00 62.59 62.69 63.34 

North Carolina Guilford 82.00 61.78 61.88 62.55 

North Carolina Haywood 78.30 63.42 63.59 63.90 

North Carolina Jackson 76.00 60.49 60.65 61.01 

North Carolina Johnston 77.30 57.23 57.29 57.82 

North Carolina Lenoir 75.30 60.34 60.41 60.80 

North Carolina Lincoln 81.00 60.65 60.73 61.21 

North Carolina Martin 75.00 62.23 62.32 62.66 

North Carolina Mecklenburg 89.30 68.17 68.22 68.54 

North Carolina New Hanover 72.30 61.79 61.85 62.20 

North Carolina Person 77.30 59.81 59.90 60.55 

North Carolina Pitt 76.30 57.93 58.02 58.46 

North Carolina Rockingham 77.00 57.75 57.83 58.42 

North Carolina Rowan 86.70 65.70 65.78 66.31 

North Carolina Swain 66.30 52.49 52.64 52.96 

North Carolina Union 79.30 58.52 58.58 58.98 

North Carolina Wake 80.30 60.77 60.84 61.34 

North Carolina Yancey 76.00 61.17 61.33 61.67 

North Dakota Billings 61.50 56.57 56.73 56.83 

North Dakota Burke 57.50 52.72 52.78 52.96 

North Dakota Cass 60.00 51.18 51.52 52.66 

North Dakota McKenzie 61.30 56.46 56.59 56.71 

North Dakota Oliver 57.70 52.93 52.97 53.04 

Ohio Allen 78.70 65.15 65.43 66.13 

Ohio Ashtabula 89.00 75.07 75.37 75.86 

Ohio Butler 83.30 67.28 67.44 67.76 

Ohio Clark 81.00 64.18 64.37 64.80 

Ohio Clermont 81.00 65.88 66.04 66.39 

Ohio Clinton 82.30 63.54 63.71 63.93 

Ohio Cuyahoga 79.70 67.43 67.31 67.51 

Ohio Delaware 78.30 63.38 63.60 64.21 

Ohio Franklin 86.30 69.39 69.66 70.35 

Ohio Geauga 79.30 63.42 63.72 64.17 

Ohio Greene 80.30 63.77 63.94 64.26 

Ohio Hamilton 84.70 67.74 67.91 68.23 

Ohio Jefferson 78.00 62.64 62.84 63.09 

Ohio Knox 77.70 61.44 61.69 62.32 

Ohio Lake 86.30 71.72 71.46 71.55 

Ohio Lawrence 70.70 58.31 58.42 58.56 

Ohio Licking 78.00 61.92 62.15 62.73 

Ohio Lorain 76.70 64.21 64.00 64.13 

Ohio Lucas 81.30 67.70 67.98 68.17 

Ohio Madison 79.70 62.16 62.40 62.94 

Ohio Mahoning 78.70 61.66 61.93 62.54 

Ohio Medina 80.30 65.36 65.66 65.89 

44 
 

Ohio Miami 76.70 60.06 60.25 60.64 

Ohio Montgomery 74.00 58.37 58.52 58.79 

Ohio Portage 83.70 66.80 67.14 67.70 

Ohio Preble 73.00 57.60 57.77 58.14 

Ohio Stark 81.00 64.54 64.81 65.35 

Ohio Summit 83.70 67.28 67.64 68.15 

Ohio Trumbull 84.30 66.18 66.47 66.97 

Ohio Warren 87.70 69.70 69.89 70.27 

Ohio Washington 82.70 68.43 68.63 68.89 

Ohio Wood 80.00 65.36 65.66 66.26 

Oklahoma Adair 75.70 63.78 63.97 64.62 

Oklahoma Canadian 76.00 61.58 61.92 62.27 

Oklahoma Cherokee 75.70 66.40 66.54 67.53 

Oklahoma Cleveland 74.70 62.14 62.38 62.84 

Oklahoma Comanche 77.50 64.22 64.39 65.02 

Oklahoma Creek 76.70 62.92 63.18 64.18 

Oklahoma Dewey 72.70 61.02 61.16 61.45 

Oklahoma Kay 78.00 64.01 64.21 64.64 

Oklahoma Mc Clain 72.00 59.90 60.12 60.44 

Oklahoma Mayes 78.50 69.61 69.75 70.39 

Oklahoma Oklahoma 80.00 65.50 65.85 66.18 

Oklahoma Ottawa 78.00 65.99 66.20 66.89 

Oklahoma Pittsburg 72.00 61.32 61.51 61.91 

Oklahoma Tulsa 79.30 67.89 68.12 68.78 

Oregon Clackamas 66.30 62.18 62.22 62.26 

Oregon Columbia 58.70 54.33 54.45 54.47 

Oregon Jackson 68.00 56.05 56.26 56.39 

Oregon Lane 69.30 59.58 59.79 60.21 

Oregon Marion 65.70 57.84 58.00 58.20 

Oregon Multnomah 56.30 57.83 57.67 57.54 

Pennsylvania Adams 76.30 60.02 60.12 60.29 

Pennsylvania Allegheny 83.70 67.83 67.98 68.28 

Pennsylvania Armstrong 83.00 65.65 65.83 66.13 

Pennsylvania Beaver 83.00 68.78 68.95 69.26 

Pennsylvania Berks 76.00 60.39 60.56 60.80 

Pennsylvania Blair 74.30 58.94 59.11 59.40 

Pennsylvania Bucks 88.00 73.97 74.03 74.13 

Pennsylvania Cambria 74.70 60.00 60.15 60.46 

Pennsylvania Centre 78.30 62.20 62.42 62.86 

Pennsylvania Chester 86.00 66.77 66.91 67.07 

Pennsylvania Clearfield 78.30 62.17 62.36 62.71 

Pennsylvania Dauphin 79.30 64.44 64.57 64.79 

Pennsylvania Delaware 83.30 68.12 68.18 68.24 

Pennsylvania Erie 81.30 68.93 69.15 69.65 

Pennsylvania Franklin 72.30 56.99 57.07 57.23 

Pennsylvania Greene 80.00 63.42 63.58 63.93 

Pennsylvania Indiana 80.00 63.12 63.28 63.58 

Pennsylvania Lackawanna 75.30 59.63 59.87 60.26 

Pennsylvania Lancaster 83.30 66.27 66.45 66.67 

Pennsylvania Lawrence 72.30 57.98 58.17 58.56 

Pennsylvania Lehigh 83.30 66.03 66.20 66.47 

Pennsylvania Luzerne 76.30 60.42 60.64 60.96 

Pennsylvania Lycoming 77.30 62.99 63.16 63.52 

45 
 

Pennsylvania Mercer 82.00 64.94 65.20 65.75 

Pennsylvania Montgomery 85.70 71.24 71.32 71.45 

Pennsylvania Northampton 84.30 66.73 66.89 67.16 

Pennsylvania Perry 77.00 60.90 61.12 61.35 

Pennsylvania Philadelphia 90.30 76.12 76.20 76.31 

Pennsylvania Tioga 77.70 64.53 64.68 65.00 

Pennsylvania Washington 78.30 63.45 63.62 63.93 

Pennsylvania Westmoreland 79.00 63.69 63.81 64.08 

Pennsylvania York 82.00 65.36 65.46 65.63 

Rhode Island Kent 84.30 69.67 69.72 69.80 

Rhode Island Providence 82.30 67.79 67.85 67.98 

Rhode Island Washington 86.00 71.10 71.15 71.25 

South Carolina Abbeville 79.00 60.78 60.90 61.39 

South Carolina Aiken 76.00 56.79 57.03 57.94 

South Carolina Anderson 76.50 57.05 57.14 57.65 

South Carolina Barnwell 73.00 54.00 54.21 54.90 

South Carolina Berkeley 67.30 52.82 52.90 53.37 

South Carolina Charleston 74.00 62.55 62.65 63.11 

South Carolina Cherokee 74.00 57.67 57.76 58.27 

South Carolina Chester 75.70 56.52 56.58 57.06 

South Carolina Chesterfield 75.00 59.34 59.43 59.77 

South Carolina Colleton 72.30 56.81 56.99 57.46 

South Carolina Darlington 76.30 59.45 59.54 59.95 

South Carolina Edgefield 70.00 52.89 53.12 54.04 

South Carolina Oconee 73.00 55.09 55.19 55.71 

South Carolina Pickens 78.70 59.16 59.23 59.81 

South Carolina Richland 82.30 60.63 60.70 61.25 

South Carolina Spartanburg 82.30 60.61 60.72 61.90 

South Carolina Union 76.00 60.12 60.19 60.62 

South Carolina Williamsburg 69.30 55.09 55.20 55.56 

South Carolina York 76.70 57.92 57.98 58.48 

South Dakota Custer 70.00 64.60 64.67 64.73 

South Dakota Jackson 67.00 61.35 61.43 61.53 

South Dakota Minnehaha 66.00 56.41 56.64 57.41 

Tennessee Anderson 77.30 55.86 56.17 56.44 

Tennessee Blount 85.30 62.23 62.52 62.76 

Tennessee Davidson 77.70 58.48 58.66 58.83 

Tennessee Hamilton 81.00 61.14 61.38 61.55 

Tennessee Jefferson 82.30 60.37 60.65 60.88 

Tennessee Knox 85.00 61.89 62.17 62.41 

Tennessee Loudon 83.00 60.51 61.02 61.29 

Tennessee Meigs 80.00 59.26 59.56 59.96 

Tennessee Rutherford 76.30 57.32 57.51 57.77 

Tennessee Sevier 80.70 59.07 59.34 59.63 

Tennessee Shelby 80.70 61.50 61.70 61.91 

Tennessee Sullivan 80.30 67.64 67.75 67.90 

Tennessee Sumner 83.00 62.79 62.97 63.12 

Tennessee Williamson 75.30 56.51 56.66 56.84 

Tennessee Wilson 78.70 60.64 60.82 61.02 

Texas Bexar 85.00 73.28 73.42 73.59 

Texas Brazoria 94.70 82.10 82.18 82.28 

Texas Brewster 64.00 56.38 56.47 56.61 

Texas Collin 90.30 72.47 72.63 72.85 

46 
 

Texas Dallas 88.30 74.61 74.73 74.94 

Texas Denton 94.00 72.51 72.69 72.94 

Texas Ellis 81.70 64.91 65.04 65.25 

Texas El Paso 77.70 70.26 70.36 70.39 

Texas Galveston 80.30 71.73 71.82 71.98 

Texas Gregg 84.30 73.47 73.59 73.80 

Texas Harris 100.70 89.17 89.24 89.29 

Texas Harrison 79.00 65.63 65.84 66.13 

Texas Hidalgo 65.70 57.30 57.43 57.59 

Texas Hood 83.00 62.70 62.87 63.15 

Texas Hunt 78.00 65.38 65.54 65.81 

Texas Jefferson 84.70 74.98 75.10 75.36 

Texas Johnson 87.00 67.73 67.89 68.13 

Texas Kaufman 74.70 63.61 63.76 63.99 

Texas Montgomery 85.00 72.76 72.80 72.80 

Texas Nueces 72.30 64.40 64.65 64.84 

Texas Orange 78.00 67.62 67.76 68.01 

Texas Parker 88.70 66.46 66.64 66.91 

Texas Rockwall 79.70 68.23 68.36 68.57 

Texas Smith 81.00 69.03 69.18 69.45 

Texas Tarrant 95.30 73.84 73.99 74.24 

Texas Travis 81.30 66.57 66.78 67.01 

Texas Victoria 72.30 63.52 63.62 63.80 

Texas Webb 61.30 54.61 54.69 54.84 

Utah Box Elder 76.00 68.29 68.41 68.51 

Utah Cache 68.70 60.96 61.09 61.19 

Utah Davis 81.30 71.92 72.27 72.37 

Utah Salt Lake 81.00 71.69 71.82 71.91 

Utah San Juan 70.30 64.99 65.03 65.08 

Utah Tooele 78.00 67.86 68.25 68.41 

Utah Utah 76.70 71.42 71.47 71.52 

Utah Washington 78.50 68.96 69.04 69.10 

Utah Weber 80.30 70.51 70.78 70.90 

Vermont Bennington 72.00 57.74 57.90 58.18 

Vermont Chittenden 69.70 58.20 58.37 58.63 

Virginia Arlington 86.70 71.91 71.99 72.12 

Virginia Caroline 80.00 61.41 61.50 61.75 

Virginia Charles City 80.30 65.69 65.75 66.03 

Virginia Chesterfield 76.70 62.43 62.48 62.71 

Virginia Fairfax 90.00 71.76 71.85 72.04 

Virginia Fauquier 72.70 57.67 57.76 57.96 

Virginia Frederick 72.30 57.62 57.72 57.93 

Virginia Hanover 81.30 64.59 64.66 64.93 

Virginia Henrico 82.00 66.09 66.14 66.37 

Virginia Loudoun 80.70 62.34 62.41 62.59 

Virginia Madison 77.70 63.21 63.29 63.50 

Virginia Page 74.00 60.13 60.23 60.48 

Virginia Prince William 78.70 61.91 61.98 62.13 

Virginia Roanoke 74.70 60.78 60.88 61.22 

Virginia Rockbridge 69.70 58.20 58.30 58.59 

Virginia Stafford 81.70 63.01 63.07 63.32 

Virginia Wythe 72.70 59.33 59.45 59.79 

Virginia Alexandria City 81.70 65.14 65.22 65.39 

47 
 

Virginia Hampton City 76.70 67.57 67.60 67.76 

Virginia Suffolk City 76.70 70.76 70.77 70.70 

Washington Clark 59.50 59.23 59.22 59.23 

Washington King 72.30 66.42 66.48 66.37 

Washington Klickitat 64.50 59.53 59.67 59.73 

Washington Pierce 68.70 62.11 62.13 62.06 

Washington Skagit 46.00 45.83 45.79 45.78 

Washington Spokane 68.30 58.43 58.72 58.75 

Washington Thurston 65.00 56.82 57.17 57.24 

Washington Whatcom 57.00 55.54 55.52 55.50 

West Virginia Berkeley 75.00 60.18 60.29 60.48 

West Virginia Cabell 78.70 64.75 64.86 65.00 

West Virginia Greenbrier 69.70 59.86 59.98 60.36 

West Virginia Hancock 75.70 61.88 62.05 62.35 

West Virginia Kanawha 77.30 60.83 61.01 61.25 

West Virginia Monongalia 75.30 58.16 58.31 58.70 

West Virginia Ohio 78.30 62.93 63.12 63.42 

West Virginia Wood 79.00 64.31 64.50 64.75 

Wisconsin Ashland 61.50 53.14 53.27 53.94 

Wisconsin Brown 73.70 62.25 62.40 62.97 

Wisconsin Columbia 72.70 59.48 59.69 60.62 

Wisconsin Dane 72.00 59.65 59.86 60.83 

Wisconsin Dodge 74.70 61.74 62.02 62.90 

Wisconsin Door 88.70 72.97 73.11 73.75 

Wisconsin Florence 66.30 57.03 57.19 57.74 

Wisconsin Fond Du Lac 73.70 61.94 62.17 62.88 

Wisconsin Forest 69.50 59.77 59.94 60.53 

Wisconsin Jefferson 74.30 61.37 61.46 62.05 

Wisconsin Kenosha 84.70 76.27 76.39 76.62 

Wisconsin Kewaunee 82.70 68.76 68.87 69.40 

Wisconsin Manitowoc 85.00 71.47 71.59 72.11 

Wisconsin Marathon 70.00 60.32 60.55 61.30 

Wisconsin Milwaukee 82.70 71.63 71.75 72.16 

Wisconsin Oneida 69.00 59.60 59.76 60.42 

Wisconsin Outagamie 74.00 61.98 62.20 62.89 

Wisconsin Ozaukee 83.30 71.67 71.78 72.19 

Wisconsin Racine 80.30 71.56 71.68 71.91 

Wisconsin Rock 74.00 61.24 61.41 62.34 

Wisconsin St Croix 69.00 58.71 58.85 59.84 

Wisconsin Sauk 69.70 57.88 58.14 58.97 

Wisconsin Sheboygan 88.00 74.71 74.84 75.33 

Wisconsin Vernon 69.70 59.00 59.21 59.99 

Wisconsin Vilas 68.70 59.51 59.67 60.31 

Wisconsin Walworth 75.70 62.74 62.91 63.50 

Wisconsin Washington 72.30 61.14 61.32 61.93 

Wisconsin Waukesha 75.00 63.24 63.38 63.88 

Wyoming Campbell 67.30 64.63 64.68 64.70 

Wyoming Sublette 70.00 65.10 65.15 65.21 

Wyoming Teton 62.70 57.02 57.12 57.18 

48 
Appendix B: 2002 CMAQ Model Performance 

Evaluation for Ozone, Particulate Matter and Air 

Toxics
 

U.S. Environmental Protection Agency 

Office of Air Quality Planning and Standards 

Air Quality Assessment Division 

Research Triangle Park, NC 27711 

January 2010 

49
 

A. Introduction 

An operational model performance evaluation for ozone, PM2.5 and its related speciated 

components, and specific air toxics (i.e., formaldehyde, acetaldehyde, benzene, 1,3-butadiene, 

acrolein, and naphthalene) was conducted using 2005 State/local monitoring sites data in order to 

estimate the ability of the CMAQ modeling system to replicate the base year concentrations for 

the 12-km Eastern and Western United States domain 1. This evaluation principally comprises 

statistical assessments of model versus observed pairs that were paired in space and time on a 

daily or weekly basis, depending on the sampling frequency of each network (measured data). 

For certain time periods with missing ozone, PM25 and air toxic observations we excluded the 

CMAQ predictions from those time periods in our calculations. It should be noted when pairing 

model and observed data that each CMAQ concentration represents a grid-cell volume-averaged 

value, while the ambient network measurements are made at specific locations. In conjunction 

with the model performance statistics, we also provide spatial plots for individual monitors of the 

calculated bias and error statistics (defined below). Statistics were generated for the 12-km 

Eastern US domain (EUS), 12-km Western US domain (WUS), and five large subregions2

: 

Midwest, Northeast, Southeast, Central, and West U.S. The Atmospheric Model Evaluation 

Tool (AMET) was used to conduct the evaluation described in this document.3 

The ozone evaluation primarily focuses on observed and predicted one-hour daily maximum 

ozone concentrations and eight-hour daily maximum ozone concentrations at a threshold of 

40ppb. This ozone model performance was limited to the ozone season modeled for the Final 

National Renewable Fuel Standard Rule (commonly known as RFS2): May, June, July, August, 

and September. Ozone ambient measurements for 2005 were obtained from the Air Quality 

System (AQS) Aerometric Information Retrieval System (AIRS). A total of 1194 ozone 

measurement sites were included for evaluation. The ozone data were measured and reported on 

an hourly basis. 

The PM2.5 evaluation focuses on PM2.5 total mass and its components including sulfate (SO4), 

nitrate (NO3), total nitrate (TNO3=NO3+HNO3), ammonium (NH4), elemental carbon (EC), and 

organic carbon (OC). The PM2.5 performance statistics were calculated for each month and 

season individually and for the entire year, as a whole. Seasons were defined as: winter 

(December-January-February), spring (March-April-May), summer (June-July-August), and fall 

(September-October-November). PM2.5 ambient measurements for 2002 were obtained from the 

1

See Air Quality Modeling Technical Support Document, 2010 (EPA 454/R-10-001): Changes to the Renewable 

Fuel Standard Program (Figure II-1) for the map of the CMAQ modeling domain. 

2

 The subregions are defined by States where: Midwest is IL, IN, MI, OH, and WI; Northeast is CT, DE, 

MA, MD, ME, NH, NJ, NY, PA, RI, and VT; Southeast is AL, FL, GA, KY, MS, NC, SC, TN, VA, and 

WV; Central is AR, IA, KS, LA, MN, MO, NE, OK, and TX; West is AK, CA, OR, WA, AZ, NM, CO, UT, WY, 

SD, ND, MT, ID, and NV. 

3

 Gilliam, R. C., W. Appel, and S. Phillips. The Atmospheric Model Evaluation Tool (AMET): Meteorology Module. 

Presented at 4th Annual CMAS Models-3 Users Conference, Chapel Hill, NC, September 26 - 28, 2005. 

(http://www.cmascenter.org/) 

50
 

 

 

 

 

following networks for model evaluation: Speciation Trends Network (STN- total of 260 sites), 

Interagency Monitoring of PROtected Visual Environments (IMPROVE- total of 204), Clean 

Air Status and Trends Network (CASTNet- total of 93), and National Acid Deposition 

Program/National Trends (NADP/NTN- toal of 297). The pollutant species included in the 

evaluation for each network are listed in Table A-1. For PM2.5 species that are measured by 

more than one network, we calculated separate sets of statistics for each network. 

Table A-1. PM2.5 monitoring networks and pollutants species included in the CMAQ 

performance evaluation. 

Ambient 

Monitoring 

Networks 

Particulate 

Species 

Wet 

Deposition 

Species 

PM2.5 

Mass SO4 NO3 TNO3 

a EC NH4 OC SO4 NO3 

IMPROVE X X X X X X 

CASTNet X X X 

STN X X X X X X 

NADP X X 

a

 TNO3 = (NO3 + HNO3) 

The air toxics evaluation focuses on specific species relevant to the RFS2 final rule, i.e., 

formaldehyde, acetaldehyde, benzene, 1,3-butadiene, acrolein, and naphthalene. Similar to the 

PM2.5 evaluation, the air toxics performance statistics were calculated for each month and 

season individually and for the entire year, as a whole to estimate the ability of the CMAQ 

modeling system to replicate the base year concentrations for the 12-km Eastern and Western 

United States domains. As mentioned above, seasons were defined as: winter (DecemberJanuary-February), spring (March-April-May), summer (June-July-August), and fall (SeptemberOctober-November). Toxic measurements for 2005 were obtained from the National Air Toxics 

Trends Stations (NATTS). Toxic measurements from 471 sites in the East and 135 sites in the 

West were included in the evaluation for the 12km Eastern and Western U.S. grids, respectively. 

There are various statistical metrics available and used by the science community for model 

performance evaluation. For a robust evaluation, the principal evaluation statistics used to 

evaluate CMAQ performance were two bias metrics, normalized mean bias and fractional bias; 

and two error metrics, normalized mean error and fractional error. 

Normalized mean bias (NMB) is used as a normalization to facilitate a range of concentration 

magnitudes. This statistic averages the difference (model - observed) over the sum of observed 

values. NMB is a useful model performance indicator because it avoids over inflating the 

observed range of values, especially at low concentrations. Normalized mean bias is defined as: 

51
 

n 

∑ ( PO − )

NMB = 1 

n *100 

∑ ( ) O 

1 

Normalized mean error (NME) is also similar to NMB, where the performance statistic is used as 

a normalization of the mean error. NME calculates the absolute value of the difference (model - 

observed) over the sum of observed values. Normalized mean error is defined as: 

∑

n 

PO −

NME = 1 

n *100 

∑ ( ) O 

1 

Fractional bias is defined as: 

n ⎛

∑ ( − ) ⎟

⎞ ⎜ P O 1 ⎜ 1 ⎟ FB = n *100, where P = predicted concentrations and O = observed ⎜ ⎛ ( P O)⎞ n ⎟ ⎜ ∑ ⎜ + ⎟ ⎟ ⎝ 1 ⎝ 2 ⎠ ⎠

concentrations. FB is a useful model performance indicator because it has the advantage of 

equally weighting positive and negative bias estimates. The single largest disadvantage in this 

estimate of model performance is that the estimated concentration (i.e., prediction, P) is found in 

both the numerator and denominator. Fractional error (FE) is similar to fractional bias except the 

absolute value of the difference is used so that the error is always positive. Fractional error is 

defined as: 

⎜ ∑

n ⎛ ⎞

⎟ 1 ⎜ 1 ⎟
 P O−

FE = *100 ⎜ ⎛ ( P O)⎞ n ⎟ ⎜ ∑

n 

⎜ + ⎟ ⎟ ⎝ 1 ⎝ 2 ⎠ ⎠

The “acceptability” of model performance was judged by comparing our CMAQ 2005 

performance results to the range of performance found in recent regional ozone, PM2.5, and air 

toxic4,5,6 model applications (e.g., Clean Air Interstate Rule7, Final PM NAAQS Rule8, and EPA’s 

4

 Phillips, S., K. Wang, C. Jang, N. Possiel, M. Strum, T. Fox, 2007: Evaluation of 2002 Multi-pollutant Platform: 

Air Toxics, Ozone, and Particulate Matter, 7th Annual CMAS Conference, Chapel Hill, NC, October 6-8, 2008. 

5

 Strum, M., Wesson, K., Phillips, S., Cook, R., Michaels, H., Brzezinski, D., Pollack, A., Jimenez, M., Shepard, S. 

Impact of using lin-level emissions on multi-pollutant air quality model predictions at regional and local scales. 17th 

Annual International Emission Inventory Conference, Portland, Oregon , June 2-5, 2008. 

6 Wesson, K., N. Fann, and B. Timin, 2010: Draft Manuscript: Air Quality and Benefits Model Responsiveness to 

Varying Horizontal Resolution in the Detroit Urban Area, Atmospheric Pollution Research, Special Issue: Air 

Quality Modeling and Analysis. 

52
 

 

 

Proposal to Designate an Emissions Control Area for Nitrogen Oxides9). These other modeling 

studies represent a wide range of modeling analyses which cover various models, model 

configurations, domains, years and/or episodes, chemical mechanisms, and aerosol modules. 

Overall, the NMB, NME, FB, and FE statistics shown in Sections B through P below for CMAQ 

predicted 2005 ozone, PM2.5, and air toxics concentrations are within the range or close to that 

found in recent OAQPS applications. The CMAQ model performance results give us confidence 

that our applications of CMAQ using this 2005 modeling platform provide a scientifically 

credible approach for assessing ozone and PM2.5 concentrations for the purposes of the RFS2 

Final Rule. We discuss in the following sections the bias and error results for the one-hour 

maximum ozone concentrations and eight-hour daily maximum ozone concentrations evaluated 

at a threshold of 40 ppb, the annual and seasonal PM2.5 and its related speciated components as 

well as specific air toxic concentrations. 

7

 See: U.S. Environmental Protection Agency; Technical Support Document for the Final Clean Air Interstate Rule: 

Air Quality Modeling; Office of Air Quality Planning and Standards; RTP, NC; March 2005 (CAIR Docket OAR2005-0053-2149). 

8

 U.S. Environmental Protection Agency, 2006. Technical Support Document for the Final PM NAAQS Rule: 

Office of Air Quality Planning and Standards, Research Triangle Park, NC. 

9

 U.S. Environmental Protection Agency, Proposal to Designate an Emissions Control Area for Nitrogen Oxides, 

Sulfur Oxides, and Particulate Matter: Technical Support Document. EPA-420-R-007, 329pp., 2009. 

(http://www.epa.gov/otaq/regs/nonroad/marine/ci/420r09007.pdf) 

53
 

B. One-Hour Daily Maximum Ozone Performance 

Ozone Performance: Threshold of 40 ppb 

Table B-1 provides one-hour daily maximum ozone model performance statistics calculated for a 

threshold of 40 ppb of observed and modeled concentrations, restricted to the ozone season 

modeled for the 12-km Eastern and Western U.S. domain and the five subregions (Midwest, 

Northeast, Southeast, Central and Western U.S.). Spatial plots of the NMB and NME statistics 

(units of percent) for individual monitors are also provided as a complement to the tabular 

statistical data (Figures B-1 – B-24). Overall, one-hour daily maximum ozone model 

performance is slightly under-predicted or near negligible in both the 12-km EUS and WUS 

when applying a threshold of 40 ppb for the modeled ozone season (May-September). For the 

12-km Eastern domain, the bias and error statistics are comparable for the aggregate of the ozone 

season and for each individual ozone month modeled, with a NMB range of -1% to -5% and a 

FB range of -0.5% to -4%, and a NME and FE range of 11% to 14%. Likewise, for the 12-km 

Western domain, the bias and error statistics are similar between the ozone seasonal aggregate 

and the individual months, with a NMB and FB approximately -2%, and a NME and FE 

approximately 14%. Hourly ozone model performance when compared across the five 

subregions shows slightly better performance in the Southeast. In general, the Northeast, 

Midwest, Central and West U.S. exhibit similar bias and error statistics for the episodes modeled. 

The month of August shows a slightly better bias and error model performance results, although 

the results are spatially and temporally comparable across the months modeled. 

Table B-1. 2005 CMAQ one-hour daily maximum ozone model performance statistics 

calculated for a threshold of 40 ppb. 

CMAQ 2005 One-Hour Maximum Ozone: 

Threshold of 40 ppb No. of Obs. NMB (%) NME (%) FB (%) FE (%) 

May 

12-km EUS 21394 -1.6 11.5 -0.8 11.6 

12-km WUS 9631 -3.4 12.8 -2.8 12.7 

Midwest 4418 0.8 10.0 1.0 10.2 

Northeast 4102 5.4 11.8 5.9 11.7 

Southeast 6424 -3.6 11.3 -3.0 11.5 

Central U.S. 4328 -6.4 13.4 -5.5 13.4 

West 8294 -3.5 12.9 -3.0 12.8 

June 

12-km EUS 19517 -3.5 12.8 -2.8 12.9 

12-km WUS 9056 -3.7 13.0 -3.2 13.0 

Midwest 4639 -4.6 12.3 -4.0 12.4 

Northeast 4148 -1.0 14.1 -0.1 14.2 

Southeast 4644 -2.7 12.5 -2.2 12.6 

Central U.S. 4062 -6.2 13.2 -5.4 13.3 

West 7737 -4.0 13.1 -3.6 13.1 

July 12-km EUS 19692 1.2 14.2 1.8 14.1 

12-km WUS 9443 0.4 16.0 1.0 15.8 

Midwest 4923 0.4 12.7 0.9 12.6 

Northeast 4445 4.2 15.2 4.8 14.9 

Southeast 4733 4.2 15.1 4.6 14.8 

54
Central U.S. 3521 -3.8 14.8 -3.1 14.9 

West 8168 0.2 16.2 0.7 16.0 

August 

12-km EUS 19643 0.1 13.9 0.8 13.8 

12-km WUS 9562 -0.8 15.5 -0.6 15.5 

Midwest 4549 0.2 12.2 1.0 12.3 

Northeast 4139 0.2 13.2 1.2 13.1 

Southeast 5303 3.6 14.9 3.9 14.5 

Central U.S. 3589 -4.1 16.2 -2.9 16.1 

West 8357 -1.0 15.7 -1.0 15.7 

September 

12-km EUS 18085 -2.2 12.0 -1.3 12.0 

12-km WUS 8725 -3.6 14.1 -3.2 14.3 

Midwest 4002 -3.6 10.7 -3.0 10.8 

Northeast 3667 -1.8 11.3 -0.7 11.3 

Southeast 5259 -0.1 12.1 0.8 12.1 

Central U.S. 3286 -6.1 14.5 -5.1 14.5 

West 7530 -4.1 14.3 -3.8 14.4 

Seasonal Aggregate 

(May – September) 

12-km EUS 98331 -1.2 12.9 -0.5 12.8 

12-km WUS 46417 -2.1 14.3 -1.7 14.2 

Midwest 22531 -1.4 11.7 -0.8 11.7 

Northeast 20501 1.4 13.3 2.3 13.1 

Southeast 26363 0.1 13.1 0.7 13.0 

Central U.S. 18786 -5.4 14.4 -4.4 14.4 

West 40086 -2.3 14.5 -2.1 14.4 

55
Figure B-1. Normalized Mean Bias (%) of one-hour daily maximum ozone (40 ppb 

threshold) by monitor for Eastern U.S., May 2005. 

Figure B-2. Normalized Mean Error (%) of one-hour daily maximum ozone (40 ppb 

threshold) by monitor for Eastern U.S., May 2005. 

56
Figure B-3. Normalized Mean Bias (%) of one-hour daily maximum ozone (40 ppb 

threshold) by monitor for Eastern U.S., June 2005. 

Figure B-4. Normalized Mean Error (%) of one-hour daily maximum ozone (40 ppb 

threshold) by monitor for Eastern U.S., June 2005. 

57
Figure B-5. Normalized Mean Bias (%) of one-hour daily maximum ozone (40 ppb 

threshold) by monitor for Eastern U.S., July 2005. 

Figure B-6. Normalized Mean Error (%) of one-hour daily maximum ozone (40 ppb 

threshold) by monitor for Eastern U.S., July 2005. 

58
Figure B-7. Normalized Mean Bias (%) of one-hour daily maximum ozone (40 ppb 

threshold) by monitor for Eastern U.S., August 2005. 

Figure B-8. Normalized Mean Error (%) of one-hour daily maximum ozone (40 ppb 

threshold) by monitor for Eastern U.S., August 2005. 

59
Figure B-9. Normalized Mean Bias (%) of one-hour daily maximum ozone (40 ppb 

threshold) by monitor for Eastern U.S., September 2005. 

Figure B-10. Normalized Mean Error (%) of one-hour daily maximum ozone (40 ppb 

threshold) by monitor for Eastern U.S., September 2005. 

60
Figure B-11. Normalized Mean Bias (%) of one-hour daily maximum ozone (40 ppb 

threshold) by monitor for Eastern U.S., seasonal aggregate 2005. 

Figure B-12. Normalized Mean Error (%) of one-hour daily maximum ozone (40 ppb 

threshold) by monitor for Eastern U.S., seasonal aggregate 2005. 

61
Figure B-13. Normalized Mean Bias (%) of one-hour daily maximum ozone (40 ppb 

threshold) by monitor for Western U.S., May 2005. 

Figure B-14. Normalized Mean Error (%) of one-hour daily maximum ozone (40 ppb 

threshold) by monitor for Western U.S., May 2005. 

62
Figure B-15. Normalized Mean Bias (%) of one-hour daily maximum ozone (40 ppb 

threshold) by monitor for Western U.S., June 2005. 

Figure B-16. Normalized Mean Error (%) of one-hour daily maximum ozone (40 ppb 

threshold) by monitor for Western U.S., June 2005. 

63
Figure B-17. Normalized Mean Bias (%) of one-hour daily maximum ozone (40 ppb 

threshold) by monitor for Western U.S., July 2005. 

Figure B-18. Normalized Mean Error (%) of one-hour daily maximum ozone (40 ppb 

threshold) by monitor for Western U.S., July 2005. 

64
Figure B-19. Normalized Mean Bias (%) of one-hour daily maximum ozone (40 ppb 

threshold) by monitor for Western U.S., August 2005. 

Figure B-20. Normalized Mean Error (%) of one-hour daily maximum ozone (40 ppb 

threshold) by monitor for Western U.S., August 2005. 

65
Figure B-21. Normalized Mean Bias (%) of one-hour daily maximum ozone (40 ppb 

threshold) by monitor for Western U.S., September 2005. 

Figure B-22. Normalized Mean Error (%) of one-hour daily maximum ozone (40 ppb 

threshold) by monitor for Western U.S., September 2005. 

66
Figure B-23. Normalized Mean Bias (%) of one-hour daily maximum ozone (40 ppb 

threshold) by monitor for Western U.S., seasonal aggregate 2005. 

Figure B-24. Normalized Mean Error (%) of one-hour daily maximum ozone (40 ppb 

threshold) by monitor for Western U.S., seasonal aggregate 2005. 

67
 

 

 

C. Eight-hour Daily Maximum Ozone Performance 

Ozone Performance: Threshold of 40 ppb 

Table C-1 presents eight-hour daily maximum ozone model performance bias and error statistics 

for the entire range of observed and modeled concentrations at a threshold of 40 ppb for the 

ozone season modeled for the 12-km Eastern and Western U.S. domain and the corresponding 

subregions defined above. Spatial plots of the NMB and NME statistics (units of percent) for 

individual monitors based on the aggregate and the individual ozone months modeled 

respectively are shown in Figures C-1 through C-24. In general, CMAQ slightly under-predicts 

eight-hour daily maximum ozone with a threshold of 40 ppb in the months of May, June and 

August. Likewise, model predictions in the EUS and WUS are slightly over-predicted in the 

months of July and August. For the 12-km Eastern domain, the bias statistics are within the 

range of approximately -4% to 7%, while the error statistics range from 11% to 14% for the 

aggregate of the ozone season and for most of the months modeled. For the 12-km Western 

domain, the bias statistics are within the range of approximately 3% to -3%, while the error 

statistics range from 11% to 13% for the aggregate of the ozone season and for the individual 

months modeled. The five subregions show relatively similar eight-hour daily maximum ozone 

performance. 

Table C-1. 2005 CMAQ eight-hour daily maximum ozone model performance statistics 

calculated for a threshold of 40 pbb. 

CMAQ 2005 Eight-Hour Maximum 

Ozone: Threshold of 40 ppb No. of Obs. NMB (%) NME (%) FB (%) FE (%) 

May 

12-km EUS 19310 -1.0 10.9 -0.4 11.0 

12-km WUS 8445 -1.6 12.0 -1.2 12.0 

Midwest 3858 0.2 10.0 0.7 10.2 

Northeast 3528 5.2 11.4 5.4 11.2 

Southeast 6019 -2.1 10.5 -1.6 10.6 

Central U.S. 3927 -5.8 12.8 -5.2 13.0 

West 7234 -1.8 12.1 -1.5 12.0 

June 

12-km EUS 17404 -2.1 11.9 -1.5 12.0 

12-km WUS 8102 -1.9 11.9 -1.6 11.9 

Midwest 4324 -3.8 11.6 -3.4 11.8 

Northeast 3590 0.3 13.1 1.0 13.2 

Southeast 3924 -0.3 11.4 0.1 11.5 

Central U.S. 3663 -5.5 12.1 -5.0 12.3 

West 6889 -2.2 12.1 -2.0 12.1 

July 12-km EUS 17045 3.3 13.4 3.6 13.3 

12-km WUS 8556 3.7 15.0 3.9 14.7 

Midwest 4429 1.8 11.8 2.3 11.8 

Northeast 3856 6.6 14.6 6.8 14.3 

Southeast 3806 7.4 15.0 7.3 14.5 

68
Central U.S. 3057 -2.3 13.2 -2.1 13.5 

West 7407 3.5 15.1 3.6 14.9 

August 

12-km EUS 16953 1.9 12.9 2.2 12.9 

12-km WUS 8523 1.6 13.9 1.5 13.9 

Midwest 4027 0.9 11.3 1.4 11.4 

Northeast 3530 1.4 12.3 2.0 12.2 

Southeast 4447 7.4 14.7 7.2 14.1 

Central U.S. 3096 -3.4 14.4 -3.1 14.8 

West 7469 1.4 14.1 1.2 14.0 

September 

12-km EUS 15190 -1.8 11.2 -1.3 11.3 

12-km WUS 7465 -2.4 13.4 -2.6 13.9 

Midwest 3265 -4.2 10.2 -4.0 10.4 

Northeast 2856 -2.3 10.6 -1.8 10.7 

Southeast 4647 1.5 11.2 2.1 11.2 

Central U.S. 2798 -6.5 13.6 -6.1 14.0 

West 6446 -2.9 13.7 -3.1 14.1 

Seasonal Aggregate 

(May – September) 

12-km EUS 85902 0.1 12.1 0.5 12.1 

12-km WUS 41091 0.0 13.3 0.1 13.3 

Midwest 19903 -0.9 11.1 -0.5 11.2 

Northeast 17360 2.4 12.6 2.9 12.4 

Southeast 22843 2.3 12.3 2.6 12.2 

Central U.S. 16541 -4.8 13.2 -4.4 13.4 

West 35445 -0.2 13.5 -0.3 13.5 

69
Figure C-1. Normalized Mean Bias (%) of eight-hour daily maximum ozone (40 ppb 

threshold) by monitor for Eastern U.S., May 2005. 

Figure C-2. Normalized Mean Error (%) of eight-hour daily maximum ozone (40 ppb 

threshold) by monitor for Eastern U.S., May 2005. 

70
Figure C-3. Normalized Mean Bias (%) of eight-hour daily maximum ozone (40 ppb 

threshold) by monitor for Eastern U.S., June 2005. 

Figure C-4. Normalized Mean Error (%) of eight-hour daily maximum ozone (40 ppb 

threshold) by monitor for Eastern U.S., June 2005. 

71
Figure C-5. Normalized Mean Bias (%) of eight-hour daily maximum ozone (40 ppb 

threshold) by monitor for Eastern U.S., July 2005. 

Figure C-6. Normalized Mean Error (%) of eight-hour daily maximum ozone (40 ppb 

threshold) by monitor for Eastern U.S., July 2005. 

72
Figure C-7. Normalized Mean Bias (%) of eight-hour daily maximum ozone (40 ppb 

threshold) by monitor for Eastern U.S., August 2005. 

Figure C-8. Normalized Mean Error (%) of eight-hour daily maximum ozone (40 ppb 

threshold) by monitor for Eastern U.S., August 2005. 

73
Figure C-9. Normalized Mean Bias (%) of eight-hour daily maximum ozone (40 ppb 

threshold) by monitor for Eastern U.S., September 2005. 

Figure C-10. Normalized Mean Error (%) of eight-hour daily maximum ozone (40 ppb 

threshold) by monitor for Eastern U.S., September 2005. 

74
Figure C-11. Normalized Mean Bias (%) of eight-hour daily maximum ozone (40 ppb 

threshold) by monitor for Eastern U.S., seasonal aggregate 2005. 

Figure C-12. Normalized Mean Error (%) of eight-hour daily maximum ozone (40 ppb 

threshold) by monitor for Eastern U.S., seasonal aggregate 2005. 

75
Figure C-13. Normalized Mean Bias (%) of eight-hour daily maximum ozone (40 ppb 

threshold) by monitor for Western U.S., May 2005. 

Figure C-14. Normalized Mean Error (%) of eight-hour daily maximum ozone (40 ppb 

threshold) by monitor for Western U.S., May 2005. 

76
Figure C-15. Normalized Mean Bias (%) of eight-hour daily maximum ozone (40 ppb 

threshold) by monitor for Western U.S., June 2005. 

Figure C-16. Normalized Mean Error (%) of eight-hour daily maximum ozone (40 ppb 

threshold) by monitor for Western U.S., June 2005. 

77
Figure C-17. Normalized Mean Bias (%) of eight-hour daily maximum ozone (40 ppb 

threshold) by monitor for Western U.S., July 2005. 

Figure C-18. Normalized Mean Error (%) of eight-hour daily maximum ozone (40 ppb 

threshold) by monitor for Western U.S., July 2005. 

78
Figure C-19. Normalized Mean Bias (%) of eight-hour daily maximum ozone (40 ppb 

threshold) by monitor for Western U.S., August 2005. 

Figure C-20. Normalized Mean Error (%) of eight-hour daily maximum ozone (40 ppb 

threshold) by monitor for Western U.S., August 2005. 

79
Figure C-21. Normalized Mean Bias (%) of eight-hour daily maximum ozone (40 ppb 

threshold) by monitor for Western U.S., September 2005. 

Figure C-22. Normalized Mean Error (%) of eight-hour daily maximum ozone (40 ppb 

threshold) by monitor for Western U.S., September 2005. 

80
Figure C-23. Normalized Mean Bias (%) of eight-hour daily maximum ozone (40 ppb 

threshold) by monitor for Western U.S., seasonal aggregate 2005. 

Figure C-24. Normalized Mean Error (%) of eight-hour daily maximum ozone (40 ppb 

threshold) by monitor for Western U.S., seasonal aggregate 2005. 

81
 

 

 

D. Annual PM2.5 Species Evaluation 

Table D-1 provides annual model performance statistics for PM2.5 and its component species for 

the 12-km Eastern domain, 12-km Western domain, and five subregions defined above (Midwest, 

Northeast, Southeast, Central, and West U.S.). Spatial plots of the NMB and NME statistics 

(units of percent) for individual monitors are also provided as a complement to the tabular 

statistical data (Figures D-1 – D-28). In the East, annual total PM2.5 mass is under-predicted 

when compared at STN and IMPROVE sites in the Southeast and Central U.S. In the West, 

annual total PM2.5 mass is under-predicted when evaluated at STN sites and IMPROVE sites, 

with better performance at STN network (bias ~ -10). Although not shown here, the mean 

observed concentrations of PM2.5 are approximately twice as high at the STN sites (EUS = 

~13μg m-3; WUS = ~11μg m-3) as the IMPROVE sites (EUS = ~7μg m-3; WUS = ~4μg m-3), 

thus illustrating the statistical differences between the urban STN and rural IMPROVE networks. 

Sulfate is consistently under-predicted at STN, IMPROVE, and CASTNet sites, with NMB 

values ranging from -32% to -5%. Overall, sulfate performance is best in the East at urban STN 

sites. Nitrate is over-predicted in the 12-km Eastern domain (NMB in the range of 5% to 66%), 

while nitrate is under-predicted in the 12-km Western domain (NMB in the range of -29% to ­

47%). Likewise, model performance of total nitrate at CASTNet sites shows an over-prediction 

in the East (NMB = 27%) and an under-prediction in the West (NMB = -3%). Ammonium 

model performance varies across the STN and CASTNet in the East and West, with a mix of 

over and under-predictions in the Eastern domain and also an under-prediction in the West. 

Elemental carbon is over-predicted at STN sites in the East and West with a bias of ~30% and 

error of ~60%. Although, EC is under-predicted at IMPROVE sites in the East and West with a 

NMB of ~ -20% and error of ~45%. Organic carbon is moderately under-predicted for all 

domains in the STN and IMPROVE networks (bias ~ -35% and error ~ 60%. Differences in 

model predictions between IMPROVE and STN networks could be attributed to both the rural 

versus urban characteristics as well as differences in the measurement methodology between the 

two networks (e.g. blank correction factors, and filter technology used). 

Table D-1. 2005 CMAQ annual PM2.5 species model performance statistics. 

CMAQ 2005 Annual PM2.5 species No. of 

Obs. NMB (%) NME (%) FB (%) FE (%) 

PM2.5 

Total Mass 

STN 

12-km EUS 11797 -0.8 37.6 -2.4 38.7 

12-km WUS 3440 -10.0 45.0 -9.5 44.4 

Midwest 2318 8.5 35.2 9.2 33.5 

Northeast 2977 10.8 41.6 9.9 38.8 

Southeast 2960 -13.7 34.0 -14.5 37.1 

Central U.S. 2523 -6.3 39.8 -9.8 44.3 

West 2826 -10.9 46.1 -10.6 45.0 

IMPROVE 12-km EUS 9321 -6.4 41.6 -7.2 43.6 

12-km WUS 10411 -19.9 44.6 -21.9 48.4 

Midwest 571 1.3 36.8 1.3 37.2 

Northeast 2339 12.1 47.7 8.1 44.3 

82
 

 

 

 

 

 

Southeast 1694 -17.6 37.5 -16.9 43.1 

Central U.S. 2376 -13.3 41.7 -11.9 46.2 

West 9258 -22.9 44.8 -23.5 48.6 

Sulfate 

STN 

12-km EUS 13897 -12.3 33.2 -9.2 35.9 

12-km WUS 3920 -17.0 42.3 -7.8 42.8 

Midwest 2495 -5.2 34.0 0.7 34.8 

Northeast 3441 -7.7 32.1 -4.0 33.9 

Southeast 3499 -14.5 30.9 -12.2 33.4 

Central U.S. 2944 -22.5 37.2 -19.5 41.6 

West 3157 -15.5 45.8 -6.7 44.0 

IMPROVE 

12-km EUS 9034 -15.2 34.5 -6.2 38.9 

12-km WUS 10002 -14.4 41.0 2.7 44.5 

Midwest 531 -12.7 32.5 -5.0 34.6 

Northeast 2253 -7.7 34.3 -0.2 37.3 

Southeast 1685 -17.8 32.7 -12.2 36.2 

Central U.S. 2350 -23.5 36.6 -16.1 40.7 

West 8896 -10.5 42.3 5.0 45.1 

CASTNet 

12-km EUS 3170 -19.3 24.8 -18.5 27.8 

12-km WUS 1142 -24.6 33.6 -16.6 35.2 

Midwest 615 -16.7 23.4 -14.8 24.8 

Northeast 786 -14.2 22.6 -12.3 24.8 

Southeast 1099 -21.5 24.7 -23.6 27.7 

Central U.S. 300 -32.2 34.3 -33.6 38.4 

West 1091 -23.7 33.8 -15.8 35.2 

Nitrate 

STN 

12-km EUS 12741 25.5 70.4 -8.1 78.1 

12-km WUS 3655 -41.7 65.3 -70.8 97.5 

Midwest 2495 29.8 64.7 17.1 63.9 

Northeast 3442 37.0 73.9 3.2 73.6 

Southeast 3499 13.1 78.2 -27.5 86.0 

Central U.S. 1812 5.2 58.8 -6.2 71.6 

West 31339 -47.3 65.4 -79.1 99.9 

IMPROVE 

12-km EUS 9027 34.2 86.9 -31.6 101.6 

12-km WUS 9987 -29.7 72.5 -93.8 124.0 

Midwest 531 20.7 69.8 -7.3 82.1 

Northeast 2248 66.4 106.9 -1.0 95.4 

Southeast 1685 42.5 106.6 -37.5 105.2 

Central U.S. 2350 22.8 72.7 -20.5 95.0 

West 8881 -45.7 75.6 -102.3 128.4 

Total 

Nitrate 

(NO3 + 

HNO3) 

CASTNet 12-km EUS 3170 27.3 40.3 21.9 38.1 

12-km WUS 1142 -3.3 34.5 6.4 39.9 

Midwest 615 26.1 37.4 26.9 34.1 

Northeast 786 40.6 46.0 34.4 42.4 

Southeast 1099 25.7 41.4 17.2 39.2 

Central U.S. 300 10.4 33.9 7.3 33.3 

83
 

 

 

 

 

 

 

 

West 1091 -4.7 35.7 6.4 40.5 

Ammonium 

STN 

12-km EUS 13897 6.7 42.3 12.6 45.4 

12-km WUS 3893 -14.9 55.3 7.1 55.0 

Midwest 2495 14.3 42.0 22.3 42.2 

Northeast 3498 14.7 44.3 25.0 46.3 

Southeast 3882 0.8 39.1 6.5 42.0 

Central U.S. 3059 -4.3 43.6 -0.2 50.4 

West 3130 -20.5 59.0 5.8 57.2 

CASTNet 

12-km EUS 3170 -1.3 34.6 0.4 35.8 

12-km WUS 1142 -14.5 38.8 -12.1 40.1 

Midwest 615 8.1 34.6 12.8 33.3 

Northeast 786 6.2 37.2 11.3 35.9 

Southeast 1099 -13.6 32.6 -13.7 36.5 

Central U.S. 300 -4.2 35.4 -1.1 39.6 

West 1091 -20.8 39.1 -13.9 40.2 

Elemental 

Carbon 

STN 

12-km EUS 14038 25.9 66.0 18.2 54.3 

12-km WUS 3814 31.1 77.7 19.5 62.5 

Midwest 2502 18.7 51.7 20.1 47.1 

Northeast 3479 37.7 70.5 26.7 54.7 

Southeast 3877 10.7 59.1 8.1 49.4 

Central U.S. 3221 48.1 86.3 26.5 64.3 

West 3015 38.7 82.8 21.0 65.1 

IMPROVE 

12-km EUS 8668 -25.9 49.1 -28.3 56.0 

12-km WUS 9495 -10.2 57.2 -17.8 60.4 

Midwest 602 -16.8 41.8 -28.3 50.4 

Northeast 2117 -4.8 48.8 -15.5 54.1 

Southeast 1584 -46.1 51.4 -51.5 62.8 

Central U.S. 2123 -31.3 49.5 -30.1 56.5 

West 8518 -9.6 58.2 -18.2 61.5 

Organic 

Carbon 

STN 

12-km EUS 12619 -35.1 52.6 -32.5 63.9 

12-km WUS 3582 -32.1 56.7 -28.2 61.3 

Midwest 2380 -37.3 51.9 -31.0 62.5 

Northeast 3323 -17.4 52.7 -13.7 60.3 

Southeast 3802 -45.7 52.9 -48.7 66.7 

Central U.S. 2259 -38.8 53.4 -37.3 66.9 

West 3060 -31.7 57.6 -27.8 61.4 

IMPROVE 

12-km EUS 8662 -29.9 50.6 -34.3 59.1 

12-km WUS 9495 -24.0 57.1 -29.4 62.8 

Midwest 601 -33.1 43.6 -39.3 53.2 

Northeast 2116 -7.7 52.4 -14.4 53.5 

Southeast 1587 -37.8 46.7 -48.0 60.2 

Central U.S. 2123 -42.5 54.2 -46.8 65.2 

West 8518 -22.3 57.3 -28.1 62.7 

84
Figure D-1. Normalized Mean Bias (%) of annual PM2.5 by monitor for Eastern U.S., 2005. 

Figure D-2. Normalized Mean Error (%) of annual PM2.5 by monitor for Eastern U.S., 

2005. 

85
Figure D-3. Normalized Mean Bias (%) of annual sulfate by monitor for Eastern U.S., 

2005. 

Figure D-4. Normalized Mean Error (%) of annual sulfate by monitor for Eastern U.S., 

2005. 

86
Figure D-5. Normalized Mean Bias (%) of annual nitrate by monitor for Eastern U.S., 

2005. 

Figure D-6. Normalized Mean Error (%) of annual nitrate by monitor for Eastern U.S., 

2005. 

87
Figure D-7. Normalized Mean Bias (%) of annual total nitrate by monitor for Eastern U.S., 

2005. 

Figure D-8. Normalized Mean Error (%) of annual total nitrate by monitor for Eastern 

U.S., 2005. 

88
Figure D-9. Normalized Mean Bias (%) of annual ammonium by monitor for Eastern U.S., 

2005. 

Figure D-10. Normalized Mean Error (%) of annual ammonium by monitor for Eastern 

U.S., 2005. 

89
Figure D-11. Normalized Mean Bias (%) of annual elemental carbon by monitor for 

Eastern U.S., 2005. 

Figure D-12. Normalized Mean Error (%) of annual elemental carbon by monitor for 

Eastern U.S., 2005. 

90
Figure D-13. Normalized Mean Bias (%) of annual organic carbon by monitor for Eastern 

U.S., 2005. 

Figure D-14. Normalized Mean Error (%) of annual organic carbon by monitor for 

Eastern U.S., 2005. 

91
Figure D-15. Normalized Mean Bias (%) of annual PM2.5 by monitor for Western U.S., 

2005. 

Figure D-16. Normalized Mean Error (%) of annual PM2.5 by monitor for Western U.S., 

2005. 

92
Figure D-17. Normalized Mean Bias (%) of annual sulfate by monitor for Western U.S., 

2005. 

Figure D-18. Normalized Mean Error (%) of annual sulfate by monitor for Western U.S., 

2005. 

93
Figure D-19. Normalized Mean Bias (%) of annual nitrate by monitor for Western U.S., 

2005. 

Figure D-20. Normalized Mean Error (%) of annual nitrate by monitor for Western U.S., 

2005. 

94
Figure D-21. Normalized Mean Bias (%) of annual total nitrate by monitor for Western 

U.S., 2005. 

Figure D-22. Normalized Mean Error (%) of annual total nitrate by monitor for Western 

U.S., 2005. 

95
Figure D-23. Normalized Mean Bias (%) of annual ammonium by monitor for Western 

U.S., 2005. 

Figure D-24. Normalized Mean Error (%) of annual ammonium by monitor for Western 

U.S., 2005. 

96
Figure D-25. Normalized Mean Bias (%) of annual elemental carbon by monitor for 

Western U.S., 2005. 

Figure D-26. Normalized Mean Error (%) of annual elemental carbon by monitor for 

Western U.S., 2005. 

97
Figure D-27. Normalized Mean Bias (%) of annual organic carbon by monitor for Western 

U.S., 2005. 

Figure D-28. Normalized Mean Error (%) of annual organic carbon by monitor for 

Western U.S., 2005. 

98
E. Seasonal PM2.5 Total Mass Performance 

Seasonal model performance statistics for PM2.5 total mass are shown in Table E-1. Spatial plots 

of the NMB and NME statistics (units of percent) for individual monitors are also provided as a 

complement to the tabular statistical data (Figures E-1 – E-16). Total PM2.5 mass is generally 

over-predicted in the cooler seasons (winter and fall) in the 12-km Eastern domain for both STN 

and IMPROVE networks. In the fall season, PM2.5 is over-predicted for Eastern STN sites with 

NMB values ranging from 0% to 15% whereas PM2.5 is under-predicted at Eastern IMPROVE 

sites. In the winter season, PM2.5 is over-predicted for Eastern STN and IMPROVE networks 

with NMB values ranging from 3% to 39% and FB values ranging from 60% to 72%. However, 

in the 12-km Western domain, PM2.5 is under-predicted in the winter (NMB in the range of -2% 

to -11%) and the fall (NMB in the range of -7% to -26%). Note that for comparison of West 

versus East STN sites, the total number of Western sites is usually less than a third of the Eastern 

sites. In the spring, CMAQ generally over-predicts PM2.5 in the East and West at urban STN and 

rural IMPROVE sites. In the summer season, PM2.5 is under-predicted in the East and West for 

STN and IMPROVE (NMB = ~ 30% and NME = ~40%). 

Table E-1. CMAQ 2005 seasonal model performance statistics for PM2.5 total mass. 

CMAQ 2005 PM2.5 total mass No. of Obs. NMB (%) NME (%) FB (%) FE (%) 

Winter 

STN 

12-km EUS 2861 8.8 37.8 5.5 36.9 

12-km WUS 895 -6.2 54.7 -3.2 53.0 

Northeast 716 22.8 40.9 18.1 35.7 

Midwest 542 7.3 32.3 8.5 31.1 

Southeast 762 -2.6 35.7 -5.0 36.6 

Central 635 10.0 43.0 4.5 43.0 

West 739 -10.9 55.0 -8.7 54.6 

IMPROVE 

12-km EUS 2213 16.3 44.7 13.4 43.3 

12-km WUS 2493 -1.9 49.3 -2.2 49.0 

Northeast 573 39.4 54.3 28.7 44.0 

Midwest 143 7.1 34.3 4.7 34.3 

Southeast 406 3.6 38.6 -0.9 41.0 

Central 546 5.6 43.1 5.5 44.6 

West 2217 -8.8 49.3 -4.3 49.4 

Spring 

STN 

12-km EUS 3159 10.5 41.2 6.5 39.1 

12-km WUS 964 0.5 43.2 -1.1 41.2 

Northeast 795 31.1 51.4 24.6 43.3 

Midwest 612 31.2 46.2 25.1 39.5 

Southeast 798 -7.3 33.1 -7.8 34.2 

Central 752 -6.6 37.1 -9.4 40.8 

West 773 3.2 45.5 -0.2 41.9 

IMPROVE 12-km EUS 2385 3.4 42.5 0.2 41.5 

99
12-km WUS 2692 -24.3 43.0 -26.6 47.0 

Northeast 630 33.9 55.7 20.2 45.5 

Midwest 153 20.6 44.4 16.7 41.5 

Southeast 429 -8.6 34.5 -7.0 36.3 

Central 601 -14.6 39.4 -12.5 43.5 

West 2389 -27.1 44.4 -28.2 47.5 

Summer 

STN 

12-km EUS 2950 -29.9 37.8 -36.2 46.5 

12-km WUS 935 -20.9 35.9 -21.0 40.3 

Northeast 754 -27.7 36.1 -30.5 41.6 

Midwest 558 -21.1 30.8 -21.6 33.8 

Southeast 722 -39.1 42.7 -49.9 54.8 

Central 701 -29.5 40.4 -38.8 53.1 

West 758 -18.2 36.2 -19.0 40.3 

IMPROVE 

12-km EUS 2277 -38.1 43.7 -45.2 53.4 

12-km WUS 2433 -27.7 43.5 -31.1 48.5 

Northeast 580 -32.6 41.2 -41.3 50.5 

Midwest 156 -31.1 63.6 -33.8 41.9 

Southeast 421 -46.6 48.4 -63.1 67.7 

Central 568 -40.7 45.9 -49.1 57.7 

West 2155 -26.0 43.7 -29.7 48.0 

Fall 

STN 

12-km EUS 2802 -0.9 36.8 1.3 37.0 

12-km WUS 962 -6.9 46.2 -4.9 45.3 

Northeast 755 15.1 44.8 10.9 39.2 

Midwest 606 0.1 32.2 4.4 31.6 

Southeast 785 -17.0 32.5 -16.0 36.0 

Central 435 6.9 42.4 11.1 42.9 

West 812 -9.1 47.2 -7.8 45.8 

IMPROVE 

12-km EUS 2256 -7.4 41.8 -8.2 43.3 

12-km WUS 2600 -21.6 46.9 -27.2 51.1 

Northeast 556 14.55 48.2 7.1 43.1 

Midwest 119 -5.3 37.1 -2.7 39.2 

Southeast 438 -23.6 36.5 -22.8 42.4 

Central 549 -8.01 44.3 -5.4 47.4 

West 2304 -26.5 46.0 -30.3 51.1 

100
Figure E-1. Normalized Mean Bias (%) of PM2.5 by monitor for 12-km Eastern U.S. 

domain, Winter 2005. 

Figure E-2. Normalized Mean Error (%) of PM2.5 by monitor for 12-km Eastern U.S. 

domain, Winter 2005. 

101
Figure E-3. Normalized Mean Bias (%) of PM2.5 by monitor for 12-km Eastern U.S. 

domain, Spring 2005. 

Figure E-4. Normalized Mean Error (%) of PM2.5 by monitor for 12-km Eastern U.S. 

domain, Spring 2005. 

102
Figure E-5. Normalized Mean Bias (%) of PM2.5 by monitor for 12-km Eastern U.S. 

domain, Summer 2005. 

Figure E-6. Normalized Mean Error (%) of PM2.5 by monitor for 12-km Eastern U.S. 

domain., Summer 2005. 

103
Figure E-7. Normalized Mean Bias (%) of PM2.5 by monitor for 12-km Eastern U.S. 

domain, Fall 2005. 

Figure E-8. Normalized Mean Error (%) of PM2.5 by monitor for 12-km Eastern U.S. 

domain, Fall 2005. 

104
Figure E-9. Normalized Mean Bias (%) of PM2.5 by monitor for 12-km Western U.S. 

domain, Winter 2005. 

Figure E-10. Normalized Mean Error (%) of PM2.5 by monitor for 12-km Western U.S. 

domain, Winter 2005. 

105
Figure E-11. Normalized Mean Bias (%) of PM2.5 by monitor for 12-km Western U.S. 

domain, Spring 2005. 

Figure E-12. Normalized Mean Error (%) of PM2.5 by monitor for 12-km Western U.S. 

domain, Spring 2005. 

106
Figure E-13. Normalized Mean Bias (%) of PM2.5 by monitor for 12-km Western U.S. 

domain, Summer 2005. 

Figure E-14. Normalized Mean Error (%) of PM2.5 by monitor for 12-km Western U.S. 

domain, Summer 2005. 

107
Figure E-15. Normalized Mean Bias (%) of PM2.5 by monitor for 12-km Western U.S. 

domain, Fall 2005. 

Figure E-16. Normalized Mean Error (%) of PM2.5 by monitor for 12-km Western U.S. 

domain, Fall 2005. 

108
F. Seasonal Sulfate Performance 

As seen in Table F-1, CMAQ generally under-predicts sulfate in the 12-km Eastern and Western 

domains throughout the entire year. Spatial plots of the NMB and NME statistics (units of 

percent) for individual monitors are also provided in Figures F-1 – F-16. Sulfate predictions 

during the winter season show NMB values ranging from -7% to -35% and in the East and with 

NMB values range from -1% to -10% in the West. In the fall season, sulfate predictions show 

NMB values ranging from -14% to -29%, across STN, IMPROVE, and CASTNet networks in 

the East and West. In the spring, sulfate predictions for the most part are under-predicted in the 

East and West, with NMB values ranging from -2% to -31%. Sulfate predictions during the 

summer season are moderately under-predicted in the East and West across the available 

monitoring data (NMB values rage from -17% to -38%. 

Table F-1. CMAQ 2005 seasonal model performance statistics for sulfate. 

CMAQ 2005 Sulfate No. of Obs. NMB (%) NME (%) FB (%) FE (%) 

Winter 

STN 

12-km EUS 3385 -15.1 38.0 -16.7 40.7 

12-km WUS 1033 -7.3 55.4 -2.6 53.7 

Northeast 828 -17.3 35.9 -21.5 37.7 

Midwest 598 -7.4 39.4 -12.7 42.2 

Southeast 963 -13.1 36.7 -12.4 37.9 

Central 766 -22.0 39.3 -21.2 44.1 

West 830 -10.3 58.1 -3.5 54.9 

IMPROVE 

12-km EUS 2018 -16.2 37.1 -6.5 42.8 

12-km WUS 2370 -1.3 50.6 22.1 53.1 

Northeast 502 -16.3 31.8 -18.9 34.7 

Midwest 129 -7.1 35.6 -12.0 36.8 

Southeast 386 -13.7 35.7 -9.5 37.3 

Central 511 -27.1 42.6 -21.6 47.2 

West 2120 8.5 51.9 26.6 53.4 

CASTNet 

12-km EUS 760 -20.4 25.4 -20.2 30.2 

12-km WUS 267 -5.4 33.2 9.4 35.5 

Northeast 193 -19.7 24.4 -24.3 28.7 

Midwest 142 -16.9 23.4 -20.2 29.1 

Southeast 264 -21.2 3-23.9 -21.5 25.3 

Central 72 -35.7 36.6 -40.2 41.7 

West 255 -1.6 34.1 11.3 35.5 

Spring 

STN 

12-km EUS 3626 -7.3 32.9 -6.2 33.6 

12-km WUS 1085 -12.3 35.0 -3.4 35.8 

Northeast 894 4.2 34.8 2.9 34.0 

Midwest 637 11.3 39.2 10.8 36.1 

Southeast 988 -13.7 28.0 -13.7 30.4 

Central 875 -23.0 33.9 -19.2 35.9 

West 867 -6.2 37.5 0.3 36.7 

IMPROVE 12-km EUS 2378 -10.3 34.0 -4.6 35.4 

109
12-km WUS 2642 -9.2 34.8 2.2 36.8 

Northeast 630 4.3 37.2 4.2 38.3 

Midwest 147 -2.3 36.2 2.2 36.0 

Southeast 436 -14.7 29.7 -11.9 31.2 

Central 605 -25.8 35.4 -18.9 36.5 

West 2352 -5.1 35.3 4.6 37.1 

CASTNet 

12-km EUS 832 -10.9 23.6 -9.6 24.6 

12-km WUS 287 -18.1 26.3 -14.8 26.3 

Northeast 206 0.4 24.4 1.1 26.2 

Midwest 155 -4.9 22.2 -2.9 21.6 

Southeast 292 -15.8 21.9 -17.1 23.8 

Central 78 -31.2 34.3 -27.9 34.1 

West 274 -16.9 25.9 -14.2 26.1 

Summer 

STN 

12-km EUS 3512 -28.1 36.2 -27.3 42.7 

12-km WUS 1075 -35.3 43.4 -28.8 45.1 

Northeast 874 -22.9 32.1 -16.5 35.3 

Midwest 621 -22.8 33.1 -12.9 34.0 

Southeast 941 -31.3 37.5 -34.2 44.8 

Central 847 -37.9 44.4 -43.8 56.4 

West 853 -35.4 45.8 -27.3 45.6 

IMPROVE 

12-km EUS 2269 -32.8 40.3 -28.4 46.7 

12-km WUS 2340 -32.2 43.8 -23.9 47.2 

Northeast 590 -26.3 37.2 -15.4 42.6 

Midwest 158 -31.3 37.0 -20.5 40.5 

Southeast 427 -37.8 42.3 -42.3 52.4 

Central 572 -37.7 43.9 -34.8 50.9 

West 2066 -30.1 44.2 -22.3 47.2 

CASTNet 

12-km EUS 792 -22.4 25.7 -25.3 31.7 

12-km WUS 295 -38.1 41.2 -40.2 45.8 

Northeast 192 -17.9 21.9 -14.5 24.1 

Midwest 161 -18.6 23.0 -16.8 25.1 

Southeast 270 -24.6 27.0 -31.9 35.0 

Central 75 -36.2 38.9 -42.5 48.3 

West 282 -38.2 41.6 -40.1 45.9 

Fall 

STN 

12-km EUS 3349 -21.0 32.3 -12.6 33.6 

12-km WUS 1095 -17.2 44.2 -7.9 44.5 

Northeast 902 -17.0 35.8 -0.2 38.3 

Midwest 639 -21.4 32.0 -13.3 32.0 

Southeast 990 -22.2 30.9 -17.7 31.9 

Central 571 -21.0 35.0 -12.3 36.7 

West 900 -14.6 48.8 -6.9 46.4 

IMPROVE 12-km EUS 2147 -23.7 35.1 -11.7 39.1 

12-km WUS 2427 -19.3 41.4 -4.0 44.0 

Northeast 531 -17.0 35.8 -0.2 38.3 

110
Midwest 97 -29.3 33.8 -27.1 36.5 

Southeast 436 -26.6 34.2 -20.8 38.3 

Central 548 -26.0 35.0 -17.7 40.2 

West 2135 -14.9 43.3 -1.5 44.6 

CASTNet 

12-km EUS 786 -21.8 24.1 -19.4 24.9 

12-km WUS 293 -22.4 30.6 -18.2 32.9 

Northeast 195 -17.2 20.8 -12.5 20.3 

Midwest 157 -23.0 24.9 -19.6 23.8 

Southeast 273 -22.9 24.5 -24.3 26.8 

Central 75 -25.2 26.7 -24.5 29.9 

West 280 -21.5 31.1 -17.6 33.0 

111
Figure F-1. Normalized Mean Bias (%) of sulfate by monitor for 12-km Eastern U.S. 

domain, Winter 2005. 

Figure F-2. Normalized Mean Error (%) of sulfate by monitor for 12-km Eastern U.S. 

domain, Winter 2005. 

112
Figure F-3. Normalized Mean Bias (%) of sulfate by monitor for 12-km Eastern U.S. 

domain, Spring 2005. 

Figure F-4. Normalized Mean Error (%) of sulfate by monitor for 12-km Eastern U.S. 

domain, Spring 2005. 

113
Figure F-5. Normalized Mean Bias (%) of sulfate by monitor for 12-km Eastern U.S. 

domain, Summer 2005. 

Figure F-6. Normalized Mean Error (%) of sulfate by monitor for 12-km Eastern U.S. 

domain, Summer 2005. 

114
Figure F-7. Normalized Mean Bias (%) of sulfate by monitor for 12-km Eastern U.S. 

domain, Fall 2005. 

Figure F-8. Normalized Mean Error (%) of sulfate by monitor for 12-km Eastern U.S. 

domain, Fall 2005. 

115
Figure F-9. Normalized Mean Bias (%) of sulfate by monitor for 12-km Western U.S. 

domain, Winter 2005. 

Figure F-10. Normalized Mean Error (%) of sulfate by monitor for 12-km Western U.S. 

domain, Winter 2005. 

116
Figure F-11. Normalized Mean Bias (%) of sulfate by monitor for 12-km Western U.S. 

domain, Spring 2005. 

Figure F-12. Normalized Mean Error (%) of sulfate by monitor for 12-km Western U.S. 

domain, Spring 2005. 

117
Figure F-13. Normalized Mean Bias (%) of sulfate by monitor for 12-km Western U.S. 

domain, Summer 2005. 

Figure F-14. Normalized Mean Error (%) of sulfate by monitor for 12-km Western U.S. 

domain, Summer 2005. 

118
Figure F-15. Normalized Mean Bias (%) of sulfate by monitor for 12-km Western U.S. 

domain, Fall 2005. 

Figure F-16. Normalized Mean Error (%) of sulfate by monitor for 12-km Western U.S. 

domain, Fall 2005. 

119
 

G. Seasonal Nitrate Performance 

Table G-1 provides the seasonal model performance statistics for nitrate and total nitrate for the 

12-km Eastern and Western domains. Spatial plots of the NMB and NME statistics (units of 

percent) for individual monitors are also provided as a complement to the tabular statistical data 

(Figures G-1 – G-32). Overall, nitrate and total nitrate performance is over-predicted in the EUS 

and under-predicted in the WUS for all of the seasonal assessments except in the winter and fall 

season, where total nitrate is under-predicted in the EUS and WUS and in the spring where 

nitrate is over-predicted in the EUS. Likewise, in the East, nitrate and total nitrate are 

moderately over-predicted during the spring and summer seasons (NMB values ranging from 

0.4% to 70%). In the East and West, nitrate and total nitrate are moderately under-predicted 

during the winter season when nitrate is most abundant (NMB values ranging from -2% to -46%). 

Table G-1. CMAQ 2005 seasonal model performance statistics for nitrate. 

CMAQ 2005 Nitrate No. of Obs. NMB (%) NME (%) FB (%) FE (%) 

Nitrate 

(Winter) 

STN 

12-km EUS 3099 -10.9 45.7 -16.1 57.8 

12-km WUS 973 -42.8 61.8 -53.1 82.1 

Northeast 829 9.1 44.7 9.1 47.5 

Midwest 598 -18.7 38.0 -15.9 44.2 

Southeast 963 -14.7 57.2 -34.6 72.8 

Central 479 -16.3 46.8 -10.8 56.7 

West 831 -46.9 64.1 -60.5 86.1 

IMPROVE 

12-km EUS 2018 -2.0 59.2 -25.0 81.6 

12-km WUS 2368 -33.6 62.1 -78.4 108.5 

Northeast 502 40.0 71.7 29.3 72.2 

Midwest 129 -29.5 43.2 -35.7 64.8 

Southeast 386 3.4 75.5 -36.2 82.1 

Central 511 -12.6 50.9 -20.1 71.9 

West 2118 -46.3 74.2 -84.5 113.9 

Total 

Nitrate 

(Winter) 

CASTNet 

12-km EUS 760 10.5 27.9 16.9 31.9 

12-km WUS 267 13.1 40.4 26.4 49.7 

Northeast 193 24.5 30.9 30.0 34.2 

Midwest 142 -6.0 19.9 0.3 20.4 

Southeast 264 17.7 31.4 14.5 32.1 

Central 72 11.4 30.3 13.3 31.1 

West 255 14.4 47.4 27.2 51.4 

Nitrate 

(Spring) 

STN 12-km EUS 3254 38.8 72.6 16.8 70.4 

12-km WUS 987 -33.5 55.5 -56.9 81.4 

Northeast 894 48.8 81.3 39.0 70.5 

Midwest 637 47.2 69.3 36.4 60.4 

Southeast 988 37.2 86.8 -3.0 81.2 

Central 503 11.6 52.3 7.9 60.3 

120
 

West 859 -38.4 56.8 -63.8 84.3 

IMPROVE 

12-km EUS 2378 41.5 84.1 -6.8 91.3 

12-km WUS 2636 -26.8 67.0 -81.2 112.3 

Northeast 630 68.9 107.3 29.9 91.3 

Midwest 147 42.3 74.5 11.1 79.3 

Southeast 436 54.7 97.9 -9.6 89.7 

Central 605 21.1 62.6 -14.0 86.3 

West 2346 -39.6 76.5 -88.7 116.9 

Total 

Nitrate 

(Spring) 

CASTNet 

12-km EUS 832 12.0 35.2 15.7 32.9 

12-km WUS 287 -12.2 31.1 -3.6 32.3 

Northeast 206 36.9 40.0 31.6 36.9 

Midwest 155 27.9 33.5 24.3 30.0 

Southeast 292 16.5 34.5 9.7 33.7 

Central 78 -1.4 31.0 -1.1 31.3 

West 274 -11.8 31.9 -3.0 32.6 

Nitrate 

(Summer) 

STN 

12-km EUS 3150 0.4 79.9 -51.1 92.7 

12-km WUS 992 -68.2 74.6 -120.1 127.1 

Northeast 874 -8.6 78.9 -49.3 91.2 

Midwest 621 30.3 79.8 -9.3 74.3 

Southeast 941 -28.4 75.3 -73.0 100.4 

Central 485 11.1 88.1 -41.5 89.7 

West 846 -70.6 74.1 -126.0 130.0 

IMPROVE 

12-km EUS 2269 -3.6 94.2 -78.4 115.2 

12-km WUS 2339 -65.9 82.3 -135.3 144.1 

Northeast 590 7.1 102.3 -55.8 104.7 

Midwest 158 16.2 86.7 -34.0 91.2 

Southeast 427 -4.9 96.3 -68.8 112.3 

Central 572 0.1 92.0 -64.2 106.9 

West 2065 -72.2 82.2 -142.3 148.6 

Total 

Nitrate 

(Summer) 

CASTNet 

12-km EUS 792 27.0 41.9 14.4 37.6 

12-km WUS 295 -13.3 30.9 -13.0 34.1 

Northeast 192 40.3 49.6 26.3 43.3 

Midwest 161 40.6 45.1 33.1 37.3 

Southeast 270 16.8 39.6 8.2 39.0 

Central 75 -6.3 26.5 -12.0 29.4 

West 282 -14.5 31.5 -13.6 34.6 

Nitrate 

(Fall) 

STN 

12-km EUS 3238 72.2 104.6 4.1 83.0 

12-km WUS 1048 -42.0 72.4 -52.3 91.6 

Northeast 902 82.7 109.2 2.3 81.3 

Midwest 639 63.1 88.4 28.5 69.7 

Southeast 990 76.6 126.2 -12.3 94.1 

Central 460 78.8 107.8 16.1 81.5 

West 896 -48.9 69.1 -63.2 92.5 

IMPROVE 12-km EUS 2140 102.3 144.2 -12.7 100.2 

121
12-km WUS 2421 -5.4 98.3 -65.0 112.1 

Northeast 526 112.6 147.0 -4.3 95.0 

Midwest 97 85.9 123.8 16.8 92.8 

Southeast 436 98.4 161.4 -25.5 107.4 

Central 548 119.5 150.5 6.0 98.9 

West 2129 -38.1 83.3 -75.4 114.1 

Total 

Nitrate 

(Fall) 

CASTNet 

12-km EUS 786 60.9 66.6 40.8 50.1 

12-km WUS 293 6.0 38.2 17.6 44.1 

Northeast 195 73.9 76.7 49.7 55.6 

Midwest 157 65.6 66.2 47.0 0.5 

Southeast 273 57.6 67.6 36.9 52.3 

Central 75 40.7 51.1 29.7 41.3 

West 280 2.2 37.0 16.9 44.4 

122
Figure G-1. Normalized Mean Bias (%) of nitrate by monitor for 12-km Eastern U.S. 

domain, Winter 2005. 

Figure G-2. Normalized Mean Error (%) of nitrate by monitor for 12-km Eastern U.S. 

domain, Winter 2005. 

123
Figure G-3. Normalized Mean Bias (%) of total nitrate by monitor for 12-km Eastern U.S. 

domain, Winter 2005. 

Figure G-4. Normalized Mean Error (%) of total nitrate by monitor for 12-km Eastern 

U.S. domain, Winter 2005. 

124
Figure G-5. Normalized Mean Bias (%) of nitrate by monitor for 12-km Eastern U.S. 

domain, Spring 2005. 

Figure G-6. Normalized Mean Error (%) of nitrate by monitor for 12-km Eastern U.S. 

domain, Spring 2005. 

125
Figure G-7. Normalized Mean Bias (%) of total nitrate by monitor for 12-km Eastern U.S. 

domain, Spring 2005. 

Figure G-8 Normalized Mean Error (%) of total nitrate by monitor for 12-km Eastern U.S. 

domain, Spring 2005. 

126
Figure G-9. Normalized Mean Bias (%) of nitrate by monitor for 12-km Eastern U.S. 

domain, Summer 2005. 

Figure G-10. Normalized Mean Error (%) of nitrate by monitor for 12-km Eastern U.S. 

domain, Summer 2005. 

127
Figure G-11. Normalized Mean Bias (%) of total nitrate by monitor for 12-km Eastern U.S. 

domain, Summer 2005. 

Figure G-12. Normalized Mean Error (%) of total nitrate by monitor for 12-km Eastern 

U.S. domain, Summer 2005. 

128
Figure G-13. Normalized Mean Bias (%) of nitrate by monitor for 12-km Eastern U.S. 

domain, Fall 2005. 

Figure G-14. Normalized Mean Error (%) of nitrate by monitor for 12-km Eastern U.S. 

domain, Fall 2005. 

129
Figure G-15. Normalized Mean Bias (%) of total nitrate by monitor for 12-km Eastern U.S. 

domain, Fall 2005. 

Figure G-16. Normalized Mean Error (%) of total nitrate by monitor for 12-km Eastern 

U.S. domain, Fall 2005. 

130
Figure G-17. Normalized Mean Bias (%) of nitrate by monitor for 12-km Western U.S. 

domain, Winter 2005. 

Figure G-18. Normalized Mean Error (%) of nitrate by monitor for 12-km Western U.S. 

domain, Winter 2005. 

131
Figure G-19. Normalized Mean Bias (%) of total nitrate by monitor for 12-km Western 

U.S. domain, Winter 2005. 

Figure G-20. Normalized Mean Error (%) of total nitrate by monitor for 12-km Western 

U.S. domain, Winter 2005. 

132
Figure G-21. Normalized Mean Bias (%) of nitrate by monitor for 12-km Western U.S. 

domain, Spring 2005. 

Figure G-22. Normalized Mean Error (%) of nitrate by monitor for 12-km Western U.S. 

domain, Spring 2005. 

133
Figure G-23. Normalized Mean Bias (%) of total nitrate by monitor for 12-km Western 

U.S. domain, Spring 2005. 

Figure G-24. Normalized Mean Error (%) of total nitrate by monitor for 12-km Western 

U.S. domain, Spring 2005. 

134
Figure G-25. Normalized Mean Bias (%) of nitrate by monitor for 12-km Western U.S. 

domain, Summer 2005. 

Figure G-26. Normalized Mean Error (%) of nitrate by monitor for 12-km Western U.S. 

domain, Summer 2005. 

135
Figure G-27. Normalized Mean Bias (%) of total nitrate by monitor for 12-km Western 

U.S. domain, Summer 2005. 

Figure G-28. Normalized Mean Error (%) of total nitrate by monitor for 12-km Western 

U.S. domain, Summer 2005. 

136
Figure G-29. Normalized Mean Bias (%) of nitrate by monitor for 12-km Western U.S. 

domain, Fall 2005. 

Figure G-30. Normalized Mean Error (%) of nitrate by monitor for 12-km Western U.S. 

domain, Fall 2005. 

137
Figure G-31. Normalized Mean Bias (%) of total nitrate by monitor for 12-km Western 

U.S. domain, Fall 2005. 

Figure G-32. Normalized Mean Error (%) of total nitrate by monitor for 12-km Western 

U.S. domain, Fall 2005. 

138
H. Seasonal Ammonium Performance 

Table H-1 lists the performance statistics for ammonium PM at the STN and CASTNet sites. 

Spatial plots of the NMB and NME statistics (units of percent) for individual monitors are also 

provided in Figures H-1 – H-16. In the winter, ammonium performance at STN and CASTNet 

networks shows an under-prediction in the EUS and WUS (NMB values range from -1% to ­

31%), except in the Northeast (NMB values range from 5% to 20%). Likewise, ammonium 

performance for the summer season shows an under-prediction in the East and West. However, 

in the spring, model predictions in the East are over-predicted, whereas ammonia predictions are 

under-predicted in the West. Ammonium predictions in the summer are moderately underpredicted for the East and West in both the rural and urban sites (NMB values ranging from -6% 

to - 37%). 

Table H-1. CMAQ 2002 seasonal model performance statistics for ammonium. 

CMAQ 2002 Ammonium No. of Obs. NMB (%) NME (%) FB (%) FE (%) 

Winter 

STN 

12-km EUS 3385 -5.3 37.5 -1.8 41.6 

12-km WUS 1032 -24.0 58.9 -8.0 63.4 

Northeast 828 4.7 34.0 8.7 34.0 

Midwest 598 -9.2 32.5 -3.7 33.6 

Southeast 963 -6.7 41.5 -4.7 44.3 

Central 766 -8.9 41.9 -5.5 50.2 

West 829 -31.0 61.1 -14.5 66.0 

CASTNet 

12-km EUS 760 -1.4 29.8 2.7 31.9 

12-km WUS 267 -6.8 37.0 1.2 40.7 

Northeast 193 20.5 37.3 22.9 34.8 

Midwest 142 -12.7 24.7 -7.8 25.1 

Southeast 264 -7.4 27.7 -7.3 29.3 

Central 72 -5.8 35.4 -4.9 42.5 

West 255 -12.1 42.1 0.7 41.4 

Spring 

STN 

12-km EUS 3626 18.8 46.4 18.5 44.4 

12-km WUS 1077 -2.0 47.4 17.5 48.7 

Northeast 894 34.7 54.9 38.0 51.7 

Midwest 637 39.0 55.0 35.7 48.6 

Southeast 988 5.9 37.1 7.1 37.8 

Central 875 -4.3 39.3 0.5 42.6 

West 859 -2.5 52.2 20.4 51.4 

CASTNet 

12-km EUS 832 24.1 39.8 18.8 34.3 

12-km WUS 287 -5.3 33.1 -3.3 32.0 

Northeast 206 42.6 48.3 33.9 38.6 

Midwest 155 42.2 49.6 35.7 40.3 

Southeast 292 5.3 29.1 4.7 29.4 

Central 78 3.7 34.1 4.9 32.9 

West 274 -10.4 32.7 -4.7 32.1 

Summer STN 12-km EUS 3512 -18.2 38.5 -9.0 48.0 

139
12-km WUS 1071 -31.6 49.6 -8.9 51.7 

Northeast 874 -17.5 36.9 -1.4 45.2 

Midwest 621 -8.5 35.8 9.1 40.7 

Southeast 941 -21.4 37.3 -14.3 44.6 

Central 847 -27.7 45.7 -27.8 60.3 

West 849 -34.7 54.6 -7.2 54.2 

CASTNet 

12-km EUS 792 -22.6 31.3 -28.0 38.5 

12-km WUS 295 -32.9 41.6 -37.3 47.8 

Northeast 192 -23.4 29.7 -25.9 34.5 

Midwest 161 -6.8 25.2 -3.6 27.0 

Southeast 270 -32.8 35.6 -44.8 48.1 

Central 75 -20.7 31.4 -24.5 38.1 

West 282 -36.9 43.5 -39.1 49.0 

Fall 

STN 

12-km EUS 3349 4.4 43.2 18.6 46.8 

12-km WUS 1081 -18.3 62.5 8.6 59.8 

Northeast 902 15.5 49.9 29.5 51.3 

Midwest 639 1.9 37.6 17.8 41.1 

Southeast 990 -2.8 40.1 9.7 43.2 

Central U.S. 571 6.9 48.5 18.6 51.0 

West 886 -24.9 64.7 5.5 61.2 

CASTNet 

12-km EUS 786 3.0 38.7 7.2 38.5 

12-km WUS 293 -3.8 43.4 -7.3 39.9 

Northeast 195 7.4 38.8 12.3 35.5 

Midwest 157 18.7 44.3 25.5 40.2 

Southeast 273 -11.3 35.6 -9.0 39.7 

Central 75 10.9 42.0 19.5 45.3 

West 280 -14.5 37.9 -10.8 38.3 

140
Figure H-1. Normalized Mean Bias (%) of ammonium by monitor for 12-km Eastern U.S. 

domain, Winter 2005. 

Figure H-2. Normalized Mean Error (%) of ammonium by monitor for 12-km Eastern 

U.S. domain, Winter 2005. 

141
Figure H-3. Normalized Mean Bias (%) of ammonium by monitor for 12-km Eastern U.S. 

domain, Spring 2005. 

Figure H-4. Normalized Mean Error (%) of ammonium by monitor for 12-km Eastern U.S. 

domain, Spring 2005. 

142
Figure H-5. Normalized Mean Bias (%) of ammonium by monitor for 12-km Eastern U.S. 

domain, Summer 2005. 

Figure H-6. Normalized Mean Error (%) of ammonium by monitor for 12-km Eastern U.S. 

domain, Summer 2005. 

143
Figure H-7. Normalized Mean Bias (%) of ammonium by monitor for 12-km Eastern U.S. 

domain, Fall 2005. 

Figure H-8. Normalized Mean Error (%) of ammonium by monitor for 12-km Eastern U.S. 

domain, Fall 2005. 

144
Figure H-9. Normalized Mean Bias (%) of ammonium by monitor for 12-km Western U.S. 

domain, Winter 2005. 

Figure H-10. Normalized Mean Error (%) of ammonium by monitor for 12-km Western 

U.S. domain, Winter 2005. 

145
Figure H-11. Normalized Mean Bias (%) of ammonium by monitor for 12-km Western U.S. 

domain, Spring 2005. 

Figure H-12. Normalized Mean Error (%) of ammonium by monitor for 12-km Western 

U.S. domain, Spring 2005. 

146
Figure H-13. Normalized Mean Bias (%) of ammonium by monitor for 12-km Western U.S. 

domain, Summer 2005. 

Figure H-14. Normalized Mean Error (%) of ammonium by monitor for 12-km Western 

U.S. domain, Summer 2005. 

147
Figure H-15. Normalized Mean Bias (%) of ammonium by monitor for 12-km Western U.S. 

domain, Fall 2005. 

Figure H-16. Normalized Mean Error (%) of ammonium by monitor for 12-km Western 

U.S. domain, Fall 2005. 

148
I. Seasonal Elemental Carbon Performance 

Table I-1 presents the seasonal performance statistics of elemental carbon for the urban and rural 

2005 monitoring data. Spatial plots of the NMB and NME statistics (units of percent) for 

individual monitors are also provided as a complement to the tabular statistical data (Figures I1 – 

I16). In the winter, elemental carbon performance is mixed across the STN and IMPROVE 

networks in the EUS and WUS, with a moderate over-prediction at STN sites and a moderate 

under-prediction at the IMPROVE sites (except during the summer season in the WUS). These 

biases and errors are not unexpected since there are known uncertainties among the scientific 

community in carbonaceous emissions/measurements, transport, and deposition processes. 

Table I-1. CMAQ 2005 seasonal model performance statistics for elemental carbon. 

CMAQ 2005 Elemental Carbon No. of Obs. NMB (%) NME (%) FB (%) FE (%) 

Winter 

STN 

12-km EUS 3441 36.3 73.2 24.7 55.5 

12-km WUS 657 8.1 71.3 5.4 65.2 

Northeast 831 53.3 74.7 36.3 53.8 

Midwest 602 53.5 78.1 41.2 56.9 

Southeast 964 17.5 60.1 7.9 46.0 

Central 811 43.7 90.5 31.0 65.6 

West 520 10.4 71.0 0.4 66.1 

IMPROVE 

12-km EUS 2072 -10.1 49.2 -16.4 53.3 

12-km WUS 2279 -19.4 57.1 -31.7 68.2 

Northeast 522 13.3 51.3 6.1 47.2 

Midwest 166 11.3 46.1 -1.9 42.4 

Southeast 386 -33.4 45.0 -34.2 52.8 

Central 474 -17.3 51.4 -13.6 52.5 

West 2066 -23.6 56.7 -35.7 70.0 

Spring 

STN 

12-km EUS 3672 31.7 68.1 22.1 54.1 

12-km WUS 1064 49.5 86.4 24.2 63.8 

Northeast 881 52.1 80.4 36.6 58.5 

Midwest 637 14.7 49.7 19.5 45.6 

Southeast 985 18.9 61.2 15.5 49.1 

Central 937 44.9 81.9 22.5 60.9 

West 822 65.2 97.3 28.5 67.2 

IMPROVE 

12-km EUS 2296 -23.9 48.5 -17.7 52.3 

12-km WUS 2563 -7.6 54.7 -11.4 54.0 

Northeast 565 1.9 48.2 -3.1 52.5 

Midwest 160 -15.3 42.0 -29.4 50.0 

Southeast 408 -43.9 49.7 -42.2 52.2 

Central 578 44.9 81.9 22.5 60.9 

West 2289 -3.6 55.1 -11.4 54.2 

Summer STN 12-km EUS 3529 27.4 66.9 17.2 58.0 

12-km WUS 1030 62.1 91.3 34.6 62.5 

149
Northeast 866 30.4 66.1 24.1 55.7 

Midwest 621 3.8 40.1 8.7 44.2 

Southeast 940 18.6 66.9 15.5 55.9 

Central 571 62.5 98.4 21.2 72.0 

West 806 78.9 10.7 41.0 65.8 

IMPROVE 

12-km EUS 2182 -42.2 51.1 -46.8 64.1 

12-km WUS 2301 1.4 60.8 0.8 56.6 

Northeast 512 -38.1 47.8 -54.2 66.6 

Midwest 160 -35.5 40.6 -52.9 58.6 

Southeast 384 -58.7 59.8 -81.2 87.0 

Central 561 -42.7 51.7 -51.9 65.5 

West 2055 5.1 63.0 4.7 57.1 

Fall 

STN 

12-km EUS 3396 10.8 56.9 8.3 49.4 

12-km WUS 1063 21.4 70.3 9.0 59.6 

Northeast 901 18.8 63.1 10.6 50.9 

Midwest 642 8.8 43.6 11.9 42.3 

Southeast 988 -5.6 52.2 -6.2 46.9 

Central 602 42.4 73.7 34.1 56.4 

West 867 26.4 74.3 7.6 61.8 

IMPROVE 

12-km EUS 2118 -25.0 47.4 -32.2 54.5 

12-km WUS 2352 -16.0 55.6 -29.2 63.7 

Northeast 518 3.6 47.7 -12.5 50.4 

Midwest 116 36.6 -25.4 -30.5 51.1 

Southeast 406 -47.8 60.9 -49.4 60.3 

Central 510 -28.4 44.1 -29.3 50.6 

West 2108 -16.8 56.8 -30.7 65.5 

150
Figure I-1. Normalized Mean Bias (%) of elemental carbon by monitor for 12-km Eastern 

U.S. domain, Winter 2005. 

Figure I-2. Normalized Mean Error (%) of elemental carbon by monitor for 12-km 

Eastern U.S. domain, Winter 2005. 

151
Figure I-3. Normalized Mean Bias (%) of elemental carbon by monitor for 12-km Eastern 

U.S. domain, Spring 2005. 

Figure I-4. Normalized Mean Error (%) of elemental carbon by monitor for 12-km 

Eastern U.S. domain, Spring 2005. 

152
Figure I-5. Normalized Mean Bias (%) of elemental carbon by monitor for 12-km Eastern 

U.S. domain, Summer 2005. 

Figure I-6. Normalized Mean Error (%) of elemental carbon by monitor for 12-km 

Eastern U.S. domain, Summer 2005. 

153
Figure I-7. Normalized Mean Bias (%) of elemental carbon by monitor for 12-km Eastern 

U.S. domain, Fall 2005. 

Figure I-8. Normalized Mean Error (%) of elemental carbon by monitor for 12-km 

Eastern U.S. domain, Fall 2005. 

154
Figure I-9. Normalized Mean Bias (%) of elemental carbon by monitor for 12-km Eastern 

U.S. domain, Winter 2005. 

Figure I-10. Normalized Mean Error (%) of elemental carbon by monitor for 12-km 

Western U.S. domain, Winter 2005. 

155
Figure I-11. Normalized Mean Bias (%) of elemental carbon by monitor for 12-km 

Western U.S. domain, Spring 2005. 

Figure I-12. Normalized Mean Error (%) of elemental carbon by monitor for 12-km 

Western U.S. domain, Spring 2005. 

156
Figure I-13. Normalized Mean Bias (%) of elemental carbon by monitor for 12-km 

Western U.S. domain, Summer 2005. 

Figure I-14. Normalized Mean Error (%) of elemental carbon by monitor for 12-km 

Western U.S. domain, Summer 2005. 

157
Figure I-15. Normalized Mean Bias (%) of elemental carbon by monitor for 12-km 

Western U.S. domain, Fall 2005. 

Figure I-16. Normalized Mean Error (%) of elemental carbon by monitor for 12-km 

Western U.S. domain, Fall 2005. 

158
J. Seasonal Organic Carbon Performance 

Seasonal organic carbon performance statistics are provided in Table J-1. Spatial plots of the 

NMB and NME statistics (units of percent) for individual monitors are also provided as a 

complement to the tabular statistical data (Figures J-1 – J-16).The model predictions generally 

show moderate under-predictions for all Eastern sites located in the urban STN sites (NMB 

values range from -12% to -67%) and rural IMPROVE sites (NMB values range from -3% to ­

50%). Organic carbon performance in the EUS and WUS shows the largest under estimations 

during the summer season. For IMPROVE, organic carbon performance shows a negative bias 

in the West (NMB= -3%) and a positive bias in the East (NMB=24%). For STN, organic carbon 

is under-predicted in the East (NMB= -12%) and West (NMB= -26%). These biases and errors 

reflect sampling artifacts among each monitoring network. In addition, uncertainties exist for 

primary organic mass emissions and secondary organic aerosol formation. Research efforts are 

ongoing to improve fire emission estimates and understand the formation of semi-volatile 

compounds, and the partitioning of SOA between the gas and particulate phases. 

Table J-1. CMAQ 2002 seasonal model performance statistics for organic carbon. 

CMAQ 2002 Organic Carbon No. of Obs. NMB (%) NME (%) FB (%) FE (%) 

Winter 

STN 

12-km EUS 2063 -12.4 51.2 -2.5 55.2 

12-km WUS 606 -25.6 62.0 -22.4 62.6 

Northeast 284 -18.1 58.7 -0.7 62.7 

Midwest 552 24.4 61.6 34.0 60.4 

Southeast 520 -32.4 44.0 -27.8 51.5 

Central 568 -22.9 45.4 -13.2 48.5 

West 507 -24.2 63.0 -22.0 64.3 

IMPROVE 

12-km EUS 2032 24.5 65.4 14.1 55.4 

12-km WUS 2432 -2.9 59.9 -4.3 58.9 

Northeast 149 4.6 43.1 16.6 45.0 

Midwest 512 89.2 104.2 63.5 71.9 

Southeast 439 -12.9 42.9 -22.1 49.9 

Central 366 -5.1 52.9 -4.5 51.4 

West 2307 -4.8 59.3 -5.1 59.4 

Spring 

STN 

12-km EUS 2241 -19.1 53.6 -15.7 60.8 

12-km WUS 656 -19.8 63.4 -13.7 64.5 

Northeast 337 -19.9 57.1 -6.6 63.8 

Midwest 583 8.5 55.3 9.8 55.8 

Southeast 590 -25.9 47.5 -22.7 54.0 

Central 579 -38.7 53.2 -45.7 68.3 

West 560 -15.9 65.9 -7.1 65.5 

IMPROVE 12-km EUS 1917 -27.2 53.0 -32.0 58.5 

12-km WUS 2369 -23.7 54.5 -26.4 56.3 

Northeast 147 -29.7 43.9 -28.6 52.1 

Midwest 508 15.6 46.4 8.5 45.0 

159
Southeast 442 -42.8 58.3 -60.6 73.0 

Central 293 -53.9 59.6 -71.6 81.0 

West 2307 -21.5 53.6 -24.4 55.1 

Summer 

STN 

12-km EUS 2690 -67.5 69.4 -95.0 100.3 

12-km WUS 832 -55.4 60.0 -76.2 83.6 

Northeast 408 -69.2 69.8 -98.4 101.2 

Midwest 754 -68.1 71.5 -88.4 97.7 

Southeast 683 -68.7 69.5 -100.9 104.5 

Central 659 -63.3 64.9 -91.1 95.7 

West 684 -54.0 59.3 -73.3 81.8 

IMPROVE 

12-km EUS 2133 -66.7 69.0 -95.5 99.0 

12-km WUS 2595 -50.4 63.7 -61.9 76.0 

Northeast 153 -70.4 70.7 -103.1 104.0 

Midwest 523 -66.2 68.5 -73.8 80.0 

Southeast 460 -73.8 74.8 -122.3 123.2 

Central 411 -74.2 74.5 -120.0 120.7 

West 2435 -49.4 63.2 -58.1 73.0 

Fall 

STN 

12-km EUS 2732 -37.6 50.2 -37.8 60.6 

12-km WUS 809 -40.4 57.9 -38.7 63.4 

Northeast 418 -44.1 51.3 -42.0 60.1 

Midwest 752 -14.6 45.4 -13.2 51.9 

Southeast 681 -47.6 52.3 -53.1 65.9 

Central 698 -43.7 50.7 -49.2 63.5 

West 657 -41.0 59.9 -39.6 66.8 

IMPROVE 

12-km EUS 2205 -25.5 47.2 -32.4 57.6 

12-km WUS 2686 -29.4 56.5 -30.0 59.9 

Northeast 149 -41.0 44.6 -44.0 53.0 

Midwest 514 4.1 43.9 0.5 45.9 

Southeast 459 -43.6 50.8 -71.3 77.4 

Central 461 -37.8 51.8 -47.2 64.6 

West 2459 -29.9 56.4 -29.5 59.5 

160
Figure J-1. Normalized Mean Bias (%) of organic carbon by monitor for 12-km Eastern 

U.S. domain, Winter 2005. 

Figure J-2. Normalized Mean Error (%) of organic carbon by monitor for 12-km Eastern 

U.S. domain, Winter 2005. 

161
Figure J-3. Normalized Mean Bias (%) of organic carbon by monitor for 12-km Eastern 

U.S. domain, Spring 2005. 

Figure J-4. Normalized Mean Error (%) of organic carbon by monitor for 12-km Eastern 

U.S. domain, Spring 2005. 

162
Figure J-5. Normalized Mean Bias (%) of organic carbon by monitor for 12-km Eastern 

U.S. domain, Summer 2005. 

Figure J-6. Normalized Mean Error (%) of organic carbon by monitor for 12-km Eastern 

U.S. domain, Summer 2005. 

163
Figure J-7. Normalized Mean Bias (%) of organic carbon by monitor for 12-km Eastern 

U.S. domain, Fall 2005. 

Figure J-8. Normalized Mean Error (%) of organic carbon by monitor for 12-km Eastern 

U.S. domain, Fall 2005. 

164
Figure J-9. Normalized Mean Bias (%) of organic carbon by monitor for 12-km Western 

U.S. domain, Winter 2005. 

Figure J-10. Normalized Mean Error (%) of organic carbon by monitor for 12-km 

Western U.S. domain, Winter 2005. 

165
Figure J-11. Normalized Mean Bias (%) of organic carbon by monitor for 12-km Western 

U.S. domain, Spring 2005. 

Figure J-12. Normalized Mean Error (%) of organic carbon by monitor for 12-km 

Western U.S. domain, Spring 2005. 

166
Figure J-13. Normalized Mean Bias (%) of organic carbon by monitor for 12-km Western 

U.S. domain, Summer 2005. 

Figure J-14. Normalized Mean Error (%) of organic carbon by monitor for 12-km 

Western U.S. domain, Summer 2005. 

167
Figure J-15. Normalized Mean Bias (%) of organic carbon by monitor for 12-km Western 

U.S. domain, Fall 2005. 

Figure J-16. Normalized Mean Error (%) of organic carbon by monitor for 12-km 

Western U.S. domain, Fall 2005. 

168
 

 

K. Annual Hazardous Air Pollutants Performance 

An annual and seasonal operational model performance evaluation for specific hazardous air 

pollutants (formaldehyde, acetaldehyde, benzene, acrolein, and 1,3-butadiene) was conducted in 

order to estimate the ability of the CMAQ modeling system to replicate the base year 

concentrations for the 12-km Eastern and Western United States domains. The annual model 

performance results are presented in Table K-1 below. Spatial plots of the NMB and NME 

statistics (units of percent) for individual monitors are also provided as a complement to the 

tabular statistical data (Figures K-1 – K-24). The seasonal results follow in Sections L-P. Toxic 

measurements from 471 sites in the East and 135 sites in the West were included in the 

evaluation and were taken from the 2005 State/local monitoring site data in the National Air 

Toxics Trends Stations (NATTS). Similar to PM2.5 and ozone, the evaluation principally 

consists of statistical assessments of model versus observed pairs that were paired in time and 

space on daily basis. 

Model predictions of annual formaldehyde, acetaldehyde and benzene showed relatively small 

bias and error percentages when compared to observations. The model yielded larger bias and 

error results for 1,3 butadiene and acrolein based on limited monitoring sites. Model 

performance for HAPs is not as good as model performance for ozone and PM2.5. Technical 

issues in the HAPs data consist of (1) uncertainties in monitoring methods; (2) limited 

measurements in time/space to characterize ambient concentrations (“local in nature”); (3) 

commensurability issues between measurements and model predictions; (4) emissions and 

science uncertainty issues may also affect model performance; and (5) limited data for estimating 

intercontinental transport that effects the estimation of boundary conditions (i.e., boundary 

estimates for some species are much higher than predicted values inside the domain). 

As with the national, annual PM2.5 and ozone CMAQ modeling, the “acceptability” of model 

performance was judged by comparing our CMAQ 2005 performance results to the limited 

performance found in recent regional multi-pollutant model applications.10,11,12 Overall, the 

normalized mean bias and error (NMB and NME), as well as the fractional bias and error (FB 

and FE) statistics shown in Table J-1 indicate that CMAQ-predicted 2005 toxics (i.e., 

observation vs. model predictions) are within the range of recent regional modeling applications. 

10 Phillips, S., K. Wang, C. Jang, N. Possiel, M. Strum, T. Fox, 2007: Evaluation of 2002 Multi-pollutant Platform: 

Air Toxics, Ozone, and Particulate Matter, 7th Annual CMAS Conference, Chapel Hill, NC, October 6-8, 2008. 

11 Strum, M., Wesson, K., Phillips, S., Cook, R., Michaels, H., Brzezinski, D., Pollack, A., Jimenez, M., Shepard, S. 

Impact of using lin-level emissions on multi-pollutant air quality model predictions at regional and local scales. 17th 

Annual International Emission Inventory Conference, Portland, Oregon , June 2-5, 2008. 

12 Wesson, K., N. Fann, and B. Timin, 2010: Draft Manuscript: Air Quality and Benefits Model Responsiveness to 

Varying Horizontal Resolution in the Detroit Urban Area, Atmospheric Pollution Research, Special Issue: Air 

Quality Modeling and Analysis. 

169
 

Table K-1. CMAQ 2005 annual model performance statistics for air toxics. 

CMAQ 2005 Annual No. of Obs. NMB (%) NME (%) FB (%) FE (%) 

Formaldehyde 

Acetaldehyde 

12-km EUS 6365 -55.5 65.3 -39.2 65.6 

12-km WUS 1928 -28.4 52.1 -30.1 60.7 

Midwest 771 -77.1 85.4 -25.8 74.0 

Northeast 1982 -30.5 51.3 -28.5 61.6 

Southeast 1246 -66.2 72.2 -51.3 70.4 

Central U.S. 1815 -43.5 51.0 -41.4 61.5 

West 1746 -25.5 52.3 -26.0 59.8 

12-km EUS 6094 -4.2 62.0 -8.2 60.3 

12-km WUS 1892 -19.2 53.7 -19.5 59.6 

Midwest 703 -12.6 58.0 -12.1 60.0 

Northeast 1969 -9.5 62.8 -9.0 63.7 

Southeast 1231 0.4 63.5 -6.2 62.2 

Central U.S. 1640 1.8 57.0 -4.3 51.1 

West 1709 -20.4 54.1 -20.1 60.6 

Benzene 

12-km EUS 11615 -32.6 66.8 -13.5 62.8 

12-km WUS 3369 -38.4 60.8 -30.4 63.9 

Midwest 1425 -8.3 72.7 25.2 62.4 

Northeast 2589 21.6 53.3 18.1 46.8 

Southeast 2426 -41.1 68.6 -17.2 59.8 

Central U.S. 4737 -47.0 68.3 -32.7 69.4 

West 2333 -30.5 61.2 -19.2 63.4 

1,3-Butadiene 

12-km EUS 8102 -74.7 85.6 -49.4 91.6 

12-km WUS 1976 -51.9 82.1 -34.5 91.7 

Midwest 516 -78.7 86.2 -48.3 81.9 

Northeast 1902 -41.6 55.5 -54.8 71.3 

Southeast 1226 -85.4 86.4 -106.2 111.5 

Central U.S. 4142 -66.5 85.9 -20.0 89.2 

West 1082 -40.8 77.5 -41.9 85.3 

Acrolein 

12-km EUS 1660 -94.4 95.0 -131.3 142.2 

12-km WUS 783 -95.7 95.7 -168.1 170.4 

Midwest n/a n/a n/a n/a n/a 

Northeast 850 -90.4 91.5 -120.5 134.2 

Southeast 278 -97.0 97.0 -156.4 157.0 

Central U.S. n/a n/a n/a n/a n/a 

West 592 -95.9 95.9 -177.6 177.6 

170
Figure K-1. Normalized Mean Bias (%) of annual formaldehyde by monitor for Eastern 

U.S., 2005. 

Figure K-2. Normalized Mean Error (%) of annual formaldehyde by monitor for Eastern 

U.S., 2005. 

171
Figure K-3. Normalized Mean Bias (%) of annual acetaldehyde by monitor for Eastern 

U.S., 2005. 

Figure K-4. Normalized Mean Error (%) of annual acetaldehyde by monitor for Eastern 

U.S., 2005. 

172
Figure K-5. Normalized Mean Bias (%) of annual benzene by monitor for Eastern U.S., 

2005. 

Figure K-6. Normalized Mean Error (%) of annual benzene by monitor for Eastern U.S., 

2005. 

173
Figure K-7. Normalized Mean Bias (%) of annual 1,3-butadiene by monitor for Eastern 

U.S., 2005. 

Figure K-8. Normalized Mean Error (%) of annual 1,3-butadiene by monitor for Eastern 

U.S., 2005. 

174
Figure K-9. Normalized Mean Bias (%) of annual acrolein by monitor for Eastern U.S., 

2005. 

Figure K-10. Normalized Mean Error (%) of annual acrolein by monitor for Eastern U.S., 

2005. 

175
Figure K-15. Normalized Mean Bias (%) of annual formaldehyde by monitor for Western 

U.S., 2005. 

Figure K-16. Normalized Mean Error (%) of annual formaldehyde by monitor for 

Western U.S., 2005. 

176
Figure K-17. Normalized Mean Bias (%) of annual acetaldehyde by monitor for Western 

U.S., 2005. 

Figure K-18. Normalized Mean Error (%) of annual acetaldehyde by monitor for Western 

U.S., 2005. 

177
Figure K-19. Normalized Mean Bias (%) of annual benzene by monitor for Western U.S., 

2005. 

Figure K-20. Normalized Mean Error (%) of annual benzene by monitor for Western U.S., 

2005. 

178
Figure K-21. Normalized Mean Bias (%) of annual 1,3-butadiene by monitor for Western 

U.S., 2005. 

Figure K-22. Normalized Mean Error (%) of annual 1,3-butadiene by monitor for 

Western U.S., 2005. 

179
Figure K-23. Normalized Mean Bias (%) of annual acrolein by monitor for Western U.S., 

2005. 

Figure K-24. Normalized Mean Error (%) of annual acrolein by monitor for Western U.S., 

2005. 

180
L. Seasonal Formaldehyde Performance 

Seasonal formaldehyde performance statistics are provided in Table L-1. Spatial plots of the 

NMB and NME statistics (units of percent) for individual monitors are also provided as a 

complement to the tabular statistical data (Figures L-1 – L-16). The model predictions generally 

show moderate under-predictions (bias and error results) for all seasons in the Eastern and 

Western sites (NMB values range from -19% to -84%; NME values range from 44% to 90%). 

Formaldehyde performance in the EUS and WUS shows the largest under estimations during the 

Midwest and Southeast areas. These biases and errors reflect sampling artifacts mentioned 

previously among the NATTS monitoring network. 

Table L-1. CMAQ 2005 seasonal model performance statistics for formaldehyde. 

CMAQ 2005 Formaldehyde No. of Obs. NMB (%) NME (%) FB (%) FE (%) 

Winter 

12-km EUS 1532 -54.2 63.0 -46.9 70.1 

12-km WUS 389 -25.1 70.9 -40.1 79.9 

Northeast 468 -35.9 48.9 -35.5 57.0 

Midwest 171 -64.2 74.1 -39.7 75.9 

Southeast 306 -66.2 68.9 -68.5 77.9 

Central 456 -49.0 62.0 -31.5 65.9 

West 347 -19.7 72.5 -35.1 79.8 

Spring 

12-km EUS 1480 -55.4 66.3 -37.5 69.3 

12-km WUS 440 -34.4 60.3 -26.4 65.9 

Northeast 472 -36.7 57.9 -26.9 66.3 

Midwest 181 -59.9 71.9 -26.7 67.9 

Southeast 249 -70.6 79.1 -41.0 77.8 

Central 435 -48.8 57.1 -42.2 69.0 

West 396 -29.4 60.2 -19.6 63.5 

Summer 

12-km EUS 1693 -55.8 65.6 -32.0 60.8 

12-km WUS 585 -26.7 44.3 -23.6 47.8 

Northeast 608 -27.5 50.6 -20.3 60.7 

Midwest 244 -84.0 90.6 -16.9 76.4 

Southeast 283 -50.6 58.3 -39.1 56.9 

Central 425 -43.2 47.2 -51.3 57.9 

West 538 -25.1 44.3 -20.8 47.1 

Fall 

12-km EUS 1660 -55.8 65.3 -41.0 63.1 

12-km WUS 514 -28.9 48.2 -33.2 56.3 

Northeast 434 -26.3 49.0 -34.3 62.8 

Midwest 175 -67.4 79.4 -23.5 75.0 

Southeast 408 -72.8 77.6 -53.2 69.6 

Central 499 -36.0 44.4 -41.3 54.1 

West 465 -27.0 48.8 -30.7 56.2 

181
Figure L-1. Normalized Mean Bias (%) of formaldehyde by monitor for 12-km Eastern 

U.S. domain, Winter 2005. 

Figure L-2. Normalized Mean Error (%) of formaldehyde by monitor for 12-km Eastern 

U.S. domain, Winter 2005. 

182
Figure L-3. Normalized Mean Bias (%) of formaldehyde by monitor for 12-km Eastern 

U.S. domain, Spring 2005. 

Figure L-4. Normalized Mean Error (%) of formaldehyde by monitor for 12-km Eastern 

U.S. domain, Spring 2005. 

183
Figure L-5. Normalized Mean Bias (%) of formaldehyde by monitor for 12-km Eastern 

U.S. domain, Summer 2005. 

Figure L-6. Normalized Mean Error (%) of formaldehyde by monitor for 12-km Eastern 

U.S. domain, Summer 2005. 

184
Figure L-7. Normalized Mean Bias (%) of formaldehyde by monitor for 12-km Eastern 

U.S. domain, Fall 2005. 

Figure L-8. Normalized Mean Error (%) of formaldehyde by monitor for 12-km Eastern 

U.S. domain, Fall 2005. 

185
Figure L-9. Normalized Mean Bias (%) of formaldehyde by monitor for 12-km Eastern 

U.S. domain, Winter 2005. 

Figure L-10. Normalized Mean Error (%) of formaldehyde by monitor for 12-km Western 

U.S. domain, Winter 2005. 

186
Figure L-11. Normalized Mean Bias (%) of formaldehyde by monitor for 12-km Western 

U.S. domain, Spring 2005. 

Figure L-12. Normalized Mean Error (%) of formaldehyde by monitor for 12-km Western 

U.S. domain, Spring 2005. 

187
Figure L-13. Normalized Mean Bias (%) of formaldehyde by monitor for 12-km Western 

U.S. domain, Summer 2005. 

Figure L-14. Normalized Mean Error (%) of formaldehyde by monitor for 12-km Western 

U.S. domain, Summer 2005. 

188
Figure L-15. Normalized Mean Bias (%) of formaldehyde by monitor for 12-km Western 

U.S. domain, Fall 2005. 

Figure L-16. Normalized Mean Error (%) of formaldehyde by monitor for 12-km Western 

U.S. domain, Fall 2005. 

189
M. Seasonal Acetaldehyde Performance 

Seasonal acetaldehyde performance statistics are provided in Table M-1. Spatial plots of the 

NMB and NME statistics (units of percent) for individual monitors are also provided as a 

complement to the tabular statistical data (Figures M-1 – M-16). Overall, the model predictions 

show moderate under-predictions for all Eastern and Western sites (NMB values range from -3% 

to -47%). Although, in the summer, acetaldehyde performance in the EUS and WUS shows a 

positive bias with over-predictions ranging from 15% in the Midwest to 84% in the Southeast. 

Similar to formaldehyde results the biases and errors reflect technical issues with observational 

data (uncertainties in monitoring methods and limited measurements in time and space). 

Table M-1. CMAQ 2005 seasonal model performance statistics for acetaldehyde. 

CMAQ 2005 Acetaldehyde No. of Obs. NMB (%) NME (%) FB (%) FE (%) 

Winter 

12-km EUS 1454 -44.8 52.0 -46.5 60.5 

12-km WUS 388 -30.2 69.9 -44.4 79.7 

Northeast 470 -47.8 54.4 -48.7 62.2 

Midwest 141 -46.1 51.8 -52.7 66.6 

Southeast 304 -41.6 52.6 -44.0 63.9 

Central 408 -34.8 40.8 -34.4 44.3 

West 346 -27.9 72.1 -42.1 81.7 

Spring 

12-km EUS 1417 -29.9 50.8 -25.6 56.5 

12-km WUS 429 -29.1 54.8 -26.3 60.8 

Northeast 473 -33.1 57.4 -23.0 66.3 

Midwest 164 -44.9 50.7 -45.5 55.9 

Southeast 245 -12.9 52.2 -4.1 57.0 

Central 392 -30.5 43.4 -29.4 44.6 

West 383 -29.7 58.3 -25.7 63.8 

Summer 

12-km EUS 1622 47.8 83.6 44.9 66.9 

12-km WUS 572 -5.6 47.0 5.9 45.4 

Northeast 576 37.6 76.1 40.9 65.6 

Midwest 238 15.0 63.5 32.0 56.9 

Southeast 278 84.8 103.7 51.9 70.0 

Central 397 54.0 87.9 49.2 69.4 

West 525 -8.9 46.1 2.6 45.0 

Fall 

12-km EUS 1601 -8.7 55.3 -11.9 56.9 

12-km WUS 503 -24.4 52.2 -23.3 59.3 

Northeast 450 -16.0 57.6 -16.9 59.8 

Midwest 160 -3.5 60.4 -7.6 63.1 

Southeast 404 -16.0 52.9 -19.0 58.8 

Central 443 2.2 47.8 -2.3 46.6 

West 455 -26.0 51.9 -25.0 59.9 

190
Figure M-1. Normalized Mean Bias (%) of acetaldehyde by monitor for 12-km Eastern 

U.S. domain, Winter 2005. 

Figure M-2. Normalized Mean Error (%) of acetaldehyde by monitor for 12-km Eastern 

U.S. domain, Winter 2005. 

191
Figure M-3. Normalized Mean Bias (%) of acetaldehyde by monitor for 12-km Eastern 

U.S. domain, Spring 2005. 

Figure M-4. Normalized Mean Error (%) of acetaldehyde by monitor for 12-km Eastern 

U.S. domain, Spring 2005. 

192
Figure M-5. Normalized Mean Bias (%) of acetaldehyde by monitor for 12-km Eastern 

U.S. domain, Summer 2005. 

Figure M-6. Normalized Mean Error (%) of acetaldehyde by monitor for 12-km Eastern 

U.S. domain, Summer 2005. 

193
Figure M-7. Normalized Mean Bias (%) of acetaldehyde by monitor for 12-km Eastern 

U.S. domain, Fall 2005. 

Figure M-8. Normalized Mean Error (%) of acetaldehyde by monitor for 12-km Eastern 

U.S. domain, Fall 2005. 

194
Figure M-9. Normalized Mean Bias (%) of acetaldehyde by monitor for 12-km Eastern 

U.S. domain, Winter 2005. 

Figure M-10. Normalized Mean Error (%) of acetaldehyde by monitor for 12-km Western 

U.S. domain, Winter 2005. 

195
Figure M-11. Normalized Mean Bias (%) of acetaldehyde by monitor for 12-km Western 

U.S. domain, Spring 2005. 

Figure M-12. Normalized Mean Error (%) of acetaldehyde by monitor for 12-km Western 

U.S. domain, Spring 2005. 

196
Figure M-13. Normalized Mean Bias (%) of acetaldehyde by monitor for 12-km Western 

U.S. domain, Summer 2005. 

Figure M-14. Normalized Mean Error (%) of acetaldehyde by monitor for 12-km Western 

U.S. domain, Summer 2005. 

197
Figure M-15. Normalized Mean Bias (%) of acetaldehyde by monitor for 12-km Western 

U.S. domain, Fall 2005. 

Figure M-16. Normalized Mean Error (%) of acetaldehyde by monitor for 12-km Western 

U.S. domain, Fall 2005. 

198
N. Seasonal Benzene Performance 

Seasonal benzene performance statistics are provided in Table N-1. Spatial plots of the NMB 

and NME statistics (units of percent) for individual monitors are also provided as a complement 

to the tabular statistical data (Figures N-1 – N-16). The model predictions typically show 

moderate bias (under-predictions) and error results for all Eastern and Western NATTS sites 

(NMB values range from -3% to -52%; NME values range from 50% to 75%). However, 

benzene performance in the Northeast shows over-predictions during all the seasons (NMB 

values range from 11% in the Summer and Fall to 30% in the Spring and Winter). Similar to the 

other HAPs modeled, these biases and errors reflect sampling artifacts among the NATTS 

monitoring network. 

Table N-1. CMAQ 2005 seasonal model performance statistics for benzene. 

CMAQ 2005 Benzene No. of Obs. NMB (%) NME (%) FB (%) FE (%) 

Winter 

12-km EUS 2846 -28.6 69.7 -6.0 60.0 

12-km WUS 781 -39.2 59.1 -39.4 64.9 

Northeast 592 31.1 56.7 25.2 46.2 

Midwest 322 27.2 72.0 35.0 55.0 

Southeast 591 -30.2 67.3 -6.4 55.8 

Central 1217 -50.3 74.1 -23.4 66.4 

West 523 -31.4 58.9 -33.8 67.4 

Spring 

12-km EUS 2888 -35.8 65.3 -19.9 63.2 

12-km WUS 769 -29.8 56.8 -30.6 62.1 

Northeast 632 28.8 52.1 19.5 45.2 

Midwest 331 -20.6 67.7 13.1 54.4 

Southeast 618 -51.9 70.9 -22.2 61.0 

Central 1169 -42.0 62.3 -37.4 69.6 

West 516 -17.0 57.0 -16.1 60.2 

Summer 

12-km EUS 2955 -36.8 67.2 -15.8 67.0 

12-km WUS 943 -28.9 58.7 -19.2 61.8 

Northeast 751 11.4 52.9 17.2 51.0 

Midwest 396 -3.2 76.8 31.4 75.3 

Southeast 563 -48.4 69.2 -26.3 62.3 

Central 1167 -51.7 68.0 -41.7 73.8 

West 675 -16.9 57.6 -3.0 58.2 

Fall 

12-km EUS 2926 -30.9 64.0 -12.3 60.9 

12-km WUS 876 -47.9 65.8 -34.2 67.0 

Northeast 614 11.7 49.8 10.9 44.1 

Midwest 376 -29.2 74.9 20.8 62.2 

Southeast 654 -34.8 66.8 -14.3 60.2 

Central 1184 -41.8 64.9 -28.6 67.9 

West 619 -44.0 67.5 -27.1 68.3 

199
Figure N-1. Normalized Mean Bias (%) of benzene by monitor for 12-km Eastern U.S. 

domain, Winter 2005. 

Figure N-2. Normalized Mean Error (%) of benzene by monitor for 12-km Eastern U.S. 

domain, Winter 2005. 

200
Figure N-3. Normalized Mean Bias (%) of benzene by monitor for 12-km Eastern U.S. 

domain, Spring 2005. 

Figure N-4. Normalized Mean Error (%) of benzene by monitor for 12-km Eastern U.S. 

domain, Spring 2005. 

201
Figure N-5. Normalized Mean Bias (%) of benzene by monitor for 12-km Eastern U.S. 

domain, Summer 2005. 

Figure N-6. Normalized Mean Error (%) of benzene by monitor for 12-km Eastern U.S. 

domain, Summer 2005. 

202
Figure N-7. Normalized Mean Bias (%) of benzene by monitor for 12-km Eastern U.S. 

domain, Fall 2005. 

Figure N-8. Normalized Mean Error (%) of benzene by monitor for 12-km Eastern U.S. 

domain, Fall 2005. 

203
Figure N-9. Normalized Mean Bias (%) of benzene by monitor for 12-km Eastern U.S. 

domain, Winter 2005. 

Figure N-10. Normalized Mean Error (%) of benzene by monitor for 12-km Western U.S. 

domain, Winter 2005. 

204
Figure N-11. Normalized Mean Bias (%) of benzene by monitor for 12-km Western U.S. 

domain, Spring 2005. 

Figure N-12. Normalized Mean Error (%) of benzene by monitor for 12-km Western U.S. 

domain, Spring 2005. 

205
Figure N-13. Normalized Mean Bias (%) of benzene by monitor for 12-km Western U.S. 

domain, Summer 2005. 

Figure N-14. Normalized Mean Error (%) of benzene by monitor for 12-km Western U.S. 

domain, Summer 2005. 

206
Figure N-15. Normalized Mean Bias (%) of benzene by monitor for 12-km Western U.S. 

domain, Fall 2005. 

Figure N-16. Normalized Mean Error (%) of benzene by monitor for 12-km Western U.S. 

domain, Fall 2005. 

207
O. Seasonal 1,3-Butadiene Performance 

Table O-1 presents the seasonal 1.3-butadiene performance statistics. Spatial plots of the NMB 

and NME statistics (units of percent) for individual monitors are also provided as a complement 

to the tabular statistical data (Figures O-1 – O-16). In general, the model predictions show 

moderate to large under-predictions for all Eastern and Western sites during all the seasons 

(NMB values range from -29% to -90%). Performance of 1,3-butadiene shows the largest under 

estimations in the areas of the Southeast and Central U.S. Likewise, the error results are large 

ranging from approximately 50% to 100%. These biases and errors reveal the underlying issues 

in the HAPs data (i.e., uncertainties in monitoring methods; limited measurements in time/space, 

proportionality issues between measurements and model predictions, emissions and science 

uncertainty issues, as well as boundary condition estimates). 

Table O-1. CMAQ 2005 seasonal model performance statistics for 1,3-butadiene. 

CMAQ 2005 1,3-Butadiene No. of Obs. NMB (%) NME (%) FB (%) FE (%) 

Winter 

12-km EUS 2028 -69.8 84.9 -26.0 88.3 

12-km WUS 501 -55.3 87.6 -30.7 100.7 

Northeast 453 -32.0 53.1 -32.5 60.0 

Midwest 133 -34.9 70.5 -2.6 64.5 

Southeast 313 -78.4 80.4 -92.9 100.1 

Central 1045 -65.2 89.0 6.7 92.4 

West 280 -39.9 83.2 -42.7 95.2 

Spring 

12-km EUS 1963 -80.3 88.8 -52.1 93.6 

12-km WUS 491 -36.5 79.4 -26.5 85.6 

Northeast 446 -42.7 52.6 -56.0 69.9 

Midwest 105 -66.6 75.3 -65.3 93.2 

Southeast 294 -83.8 84.4 -108.1 111.0 

Central 1011 -67.8 88.1 -17.8 88.4 

West 281 -29.4 75.3 -33.8 81.0 

Summer 

12-km EUS 2003 -79.1 86.7 -63.1 93.8 

12-km WUS 482 -47.9 72.6 -40.2 86.0 

Northeast 489 -47.8 55.7 -66.4 77.0 

Midwest 122 -94.5 95.3 -73.6 89.9 

Southeast 279 -90.6 91.0 -122.1 125.3 

Central 1059 -71.8 85.0 -39.5 90.0 

West 246 -42.1 65.5 -46.7 78.0 

Fall 

12-km EUS 2108 -69.3 81.1 -56.2 90.6 

12-km WUS 502 -57.0 80.3 -40.6 94.3 

Northeast 514 -49.1 60.7 -62.4 77.1 

Midwest 156 -62.0 70.3 -56.1 82.9 

Southeast 340 -87.7 88.8 -103.7 111.1 

Central 1027 -60.3 80.5 -29.2 86.0 

West 275 -47.9 76.7 -45.0 86.3 

208
Figure O-1. Normalized Mean Bias (%) of 1,3-butadiene by monitor for 12-km Eastern 

U.S. domain, Winter 2005. 

Figure O-2. Normalized Mean Error (%) of 1,3-butadiene by monitor for 12-km Eastern 

U.S. domain, Winter 2005. 

209
Figure O-3. Normalized Mean Bias (%) of 1,3-butadiene by monitor for 12-km Eastern 

U.S. domain, Spring 2005. 

Figure O-4. Normalized Mean Error (%) of 1,3-butadiene by monitor for 12-km Eastern 

U.S. domain, Spring 2005. 

210
Figure O-5. Normalized Mean Bias (%) of 1,3-butadiene by monitor for 12-km Eastern 

U.S. domain, Summer 2005. 

Figure O-6. Normalized Mean Error (%) of 1,3-butadiene by monitor for 12-km Eastern 

U.S. domain, Summer 2005. 

211
Figure O-7. Normalized Mean Bias (%) of 1,3-butadiene by monitor for 12-km Eastern 

U.S. domain, Fall 2005. 

Figure O-8. Normalized Mean Error (%) of 1,3-butadiene by monitor for 12-km Eastern 

U.S. domain, Fall 2005. 

212
Figure O-9. Normalized Mean Bias (%) of 1,3-butadiene by monitor for 12-km Eastern 

U.S. domain, Winter 2005. 

Figure O-10. Normalized Mean Error (%) of 1,3-butadiene by monitor for 12-km Western 

U.S. domain, Winter 2005. 

213
Figure O-11. Normalized Mean Bias (%) of 1,3-butadiene by monitor for 12-km Western 

U.S. domain, Spring 2005. 

Figure O-12. Normalized Mean Error (%) of 1,3-butadiene by monitor for 12-km Western 

U.S. domain, Spring 2005. 

214
Figure O-13. Normalized Mean Bias (%) of 1,3-butadiene by monitor for 12-km Western 

U.S. domain, Summer 2005. 

Figure O-14. Normalized Mean Error (%) of 1,3-butadiene by monitor for 12-km Western 

U.S. domain, Summer 2005. 

215
Figure O-15. Normalized Mean Bias (%) of 1,3-butadiene by monitor for 12-km Western 

U.S. domain, Fall 2005. 

Figure O-16. Normalized Mean Error (%) of 1,3-butadiene by monitor for 12-km Western 

U.S. domain, Fall 2005. 

216
P. Seasonal Acrolein Performance 

Seasonal acrolein performance statistics are provided in Table P-1. Spatial plots of the NMB and 

NME statistics (units of percent) for individual monitors are also provided as a complement to 

the tabular statistical data (Figures P-1 – P-16). The model predictions generally show large 

under-predictions for all Eastern and Western sites (NMB values range from -85% to -97%). 

Acrolein performance in the EUS and WUS shows the similar under estimations during each 

season. These biases and errors reflect sampling artifacts among each monitoring network 

mentioned above. 

Table P-1. CMAQ 2005 seasonal model performance statistics for acrolein. 

CMAQ 2005 Acrolein No. of Obs. NMB (%) NME (%) FB (%) FE (%) 

Winter 

12-km EUS 423 -91.9 92.7 -123.1 133.8 

12-km WUS 195 -93.7 93.7 -160.5 162.1 

Northeast 216 -85.6 87.2 -108.4 119.7 

Midwest n/a n/a n/a n/a n/a 

Southeast 80 -96.6 96.6 -165.9 165.9 

Central n/a n/a n/a n/a n/a 

West 153 -94.0 94.0 -169.1 169.1 

Spring 

12-km EUS 298 -86.3 87.3 -118.2 128.0 

12-km WUS 190 -94.7 94.7 -167.1 167.9 

Northeast 180 -87.7 88.7 -121.3 129.2 

Midwest n/a n/a n/a n/a n/a 

Southeast 25 -76.7 76.9 -107.4 108.1 

Central n/a n/a n/a n/a n/a 

West 143 -95.1 95.1 -177.3 177.3 

Summer 

12-km EUS 447 -95.8 96.5 -132.9 151.5 

12-km WUS 187 -96.4 96.4 -171.7 177.3 

Northeast 251 -93.0 94.8 -119.1 147.9 

Midwest n/a n/a n/a n/a n/a 

Southeast 52 -93.9 93.9 -142.1 142.2 

Central n/a n/a n/a n/a n/a 

West n/a n/a n/a n/a n/a 

Fall 

12-km EUS 492 -96.3 96.4 -144.8 149.5 

12-km WUS 211 -96.8 96.8 -172.8 174.3 

Northeast 203 -92.9 93.1 -134.5 137.3 

Midwest 29 -98.3 98.5 -145.4 153.5 

Southeast 121 -98.1 98.2 -166.5 167.5 

Central n/a n/a n/a n/a n/a 

West 160 -97.0 97.0 -180.9 180.9 

217
Figure P-1. Normalized Mean Bias (%) of acrolein by monitor for 12-km Eastern U.S. 

domain, Winter 2005. 

Figure P-2. Normalized Mean Error (%) of acrolein by monitor for 12-km Eastern U.S. 

domain, Winter 2005. 

218
Figure P-3. Normalized Mean Bias (%) of acrolein by monitor for 12-km Eastern U.S. 

domain, Spring 2005. 

Figure P-4. Normalized Mean Error (%) of acrolein by monitor for 12-km Eastern U.S. 

domain, Spring 2005. 

219
Figure P-5. Normalized Mean Bias (%) of acrolein by monitor for 12-km Eastern U.S. 

domain, Summer 2005. 

Figure P-6. Normalized Mean Error (%) of acrolein by monitor for 12-km Eastern U.S. 

domain, Summer 2005. 

220
Figure P-7. Normalized Mean Bias (%) of acrolein by monitor for 12-km Eastern U.S. 

domain, Fall 2005. 

Figure P-8. Normalized Mean Error (%) of acrolein by monitor for 12-km Eastern U.S. 

domain, Fall 2005. 

221
Figure P-9. Normalized Mean Bias (%) of acrolein by monitor for 12-km Eastern U.S. 

domain, Winter 2005. 

Figure P-10. Normalized Mean Error (%) of acrolein by monitor for 12-km Western U.S. 

domain, Winter 2005. 

222
Figure P-11. Normalized Mean Bias (%) of acrolein by monitor for 12-km Western U.S. 

domain, Spring 2005. 

Figure P-12. Normalized Mean Error (%) of acrolein by monitor for 12-km Western U.S. 

domain, Spring 2005. 

223
Figure P-13. Normalized Mean Bias (%) of acrolein by monitor for 12-km Western U.S. 

domain, Summer 2005. 

Figure P-14. Normalized Mean Error (%) of acrolein by monitor for 12-km Western U.S. 

domain, Summer 2005. 

224
Figure P-15. Normalized Mean Bias (%) of acrolein by monitor for 12-km Western U.S. 

domain, Fall 2005. 

Figure P-16. Normalized Mean Error (%) of acrolein by monitor for 12-km Western U.S. 

domain, Fall 2005. 

225
Q. Annual Nitrate and Sulfate Deposition Performance 

Annual nitrate and sulfate deposition performance statistics are provided in Table Q-1. Spatial 

plots of the NMB and NME statistics (units of percent) for individual monitors are also provided 

as a complement to the tabular statistical data (Figures Q-1 – Q-8). The model predictions for 

annual nitrate deposition generally show small under-predictions for the Eastern and Western 

NADP sites (NMB values range from -3% to -18%). Sulfate deposition performance in the EUS 

and WUS shows the similar over predictions (NMB values range from 3% to 14%), except for 

predicted under-prediction in the Central US (NMB = -9.9%). The errors for both annual nitrate 

and sulfate are relatively moderate with values ranging from 54% to 87% which reflect scatter in 

the model predictions o observation comparison. 

Table Q-1. CMAQ 2005 seasonal model performance statistics for acrolein. 

CMAQ 2005 Total Deposition No. of Obs. NMB (%) NME (%) FB (%) FE (%) 

Nitrate 

12-km EUS 7381 -8.6 61.3 -5.1 54.2 

12-km WUS 2732 -16.3 68.4 -16.1 83.3 

Northeast 1658 1.0 57.4 -3.1 65.7 

Midwest 1391 -3.3 59.7 -2.0 67.5 

Southeast 1980 -3.7 63.8 -6.5 70.7 

Central 1229 -18.5 61.4 -17.6 78.6 

West 2400 -13.4 71.8 -15.4 84.1 

Sulfate 

12-km EUS 7381 6.2 66.5 4.7 75.3 

12-km WUS 2732 3.7 75.9 3.2 86.5 

Northeast 1658 11.3 63.7 16.0 67.2 

Midwest 1391 13.9 61.7 21.4 69.9 

Southeast 1980 7.4 71.0 6.0 73.8 

Central 1229 -9.9 64.4 -3.5 80.3 

West 2400 11.6 80.99 5.4 87.1 

226
Figure Q-1. Normalized Mean Bias (%) of annual nitrate deposition by monitor for 

Eastern U.S., 2005. 

Figure Q-2. Normalized Mean Error (%) of annual nitrate by monitor for Eastern U.S., 

2005. 

227
Figure Q-3. Normalized Mean Bias (%) of annual nitrate deposition by monitor for 

Western U.S., 2005. 

Figure Q-4. Normalized Mean Error (%) of annual nitrate deposition by monitor for 

Western U.S., 2005. 

228
Figure Q-5. Normalized Mean Bias (%) of annual sulfate deposition by monitor for 

Eastern U.S., 2005. 

Figure Q-6. Normalized Mean Error (%) of annual sulfate deposition by monitor for 

Eastern U.S., 2005. 

229
Figure Q-7. Normalized Mean Bias (%) of annual sulfate deposition by monitor for 

Western U.S., 2005. 

Figure Q-8. Normalized Mean Error (%) of annual sulfate deposition by monitor for 

Western U.S., 2005. 

230
United States Office of Air Quality Planning and Standards Publication No. EPA-454/R-10-001 

Environmental Protection Air Quality Assessment Division February, 2010 Agency Research Triangle Park, NC