Appendix J 

Model Performance Evaluation 
TABLE OF CONTENTS

MODEL PERFORMANCE EVALUATION................................................................................. 1 

I. Air Quality Modeling ................................................................................................................. 1 

A. Air Quality Model Configuration ......................................................................................... 1 

B. Secondary Organic Aerosols Modifications ......................................................................... 2 

II. Model Performance Statistics ................................................................................................... 3 

A. 12km Domain Statistics – Selected Regions ........................................................................ 5 

B. Metrolina Nonattainment Area and Monitor Statistics ......................................................... 6 

III. Spatial Plots ............................................................................................................................. 8 

IV. Scatter Plots ........................................................................................................................... 40 

A. 12km Domain Scatter Plots – VISTAS/ASIP States Only................................................. 40 

B. 12km Domain Scatter Plots – North Carolina .................................................................... 46 

C. 12km Domain Scatter Plots – South Carolina .................................................................... 52 

D. Metrolina Monitor Specific Scatter Plots ........................................................................... 58 

V. Time Series ............................................................................................................................. 67 

A. 12 km Domain Time Series Plots – VISTAS/ASIP States Only........................................ 67

B. 12 km Domain Time Series Plots – North Carolina ........................................................... 73 

C. 12 km Domain Time Series Plots – South Carolina ........................................................... 79 

D. Metrolina Monitor Specific Time Series Plots ................................................................... 85 
LIST OF FIGURES 

Figure J-1 CMAQ nested 12 km grid in the CMAQ 36 km grid. Lower left x, y of the 36 km 

grid is at -2736000, -20880000............................................................................................... 2 

Figure J-2: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For May 24, 2002 ..................................................................... 9 

Figure J-3: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For May 25, 2002 ................................................................... 10 

Figure J-4: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For May 26, 2002 ................................................................... 11 

Figure J-5: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For June 1, 2002 ..................................................................... 12 

Figure J-6: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For June 2, 2002 ..................................................................... 13 

Figure J-7: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For June 3, 2002 ..................................................................... 14 

Figure J-8: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For June 9, 2002 ..................................................................... 15 

Figure J-9: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For June 10, 2002 ................................................................... 16 

Figure J-10: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For June 11, 2002 ................................................................... 17 

Figure J-11: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For June 12, 2002 ................................................................... 18 

Figure J-12: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For June 13, 2002 ................................................................... 19 

Figure J-13: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For July 1, 2002 ...................................................................... 20 

Figure J-14: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For July 2, 2002 ...................................................................... 21 

Figure J-15: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For July 3, 2002 ...................................................................... 22 

Figure J-16: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For July 4, 2002 ...................................................................... 23 

Figure J-17: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For July 5, 2002 ...................................................................... 24 

Figure J-18: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For July 6, 2002 ...................................................................... 25 

Figure J-19: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For July 8, 2002 ...................................................................... 26 
Figure J-20: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For July 9, 2002 ...................................................................... 27 

Figure J-21: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For July 16, 2002 .................................................................... 28 

Figure J-22: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For July 17, 2002 .................................................................... 29 

Figure J-23: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For July 18, 2002 .................................................................... 30 

Figure J-24: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For July 21, 2002 .................................................................... 31 

Figure J-25: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For August 1, 2002 ................................................................. 32 

Figure J-26: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For August 2, 2002 ................................................................. 33 

Figure J-27: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For August 5, 2002 ................................................................. 34 

Figure J-28: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For August 10, 2002 ............................................................... 35 

Figure J-29: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For August 11, 2002 ............................................................... 36 

Figure J-30: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For August 12, 2002 ............................................................... 37 

Figure J-31: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For August 21, 2002 ............................................................... 38 

Figure J-32: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For August 23, 2002 ............................................................... 39 

Figure J-33: 12km Domain – VISTAS/ASIP States Only 1-hour (top) And 8-hour (bottom) 

Scatter Plots For May............................................................................................................ 41 

Figure J-34: 12km Domain – VISTAS/ASIP States Only 1-hour (top) And 8-hour (bottom) 

Scatter Plots For June............................................................................................................ 42 

Figure J-35: 12km Domain – VISTAS/ASIP States Only 1-hour (top) And 8-hour (bottom) 

Scatter Plots For July ............................................................................................................ 43 

Figure J-36: 12km Domain – VISTAS/ASIP States Only 1-hour (top) And 8-hour (bottom) 

Scatter Plots For August ....................................................................................................... 44 

Figure J-37: 12km Domain – VISTAS/ASIP States Only 1-hour (top) And 8-hour (bottom) 

Scatter Plots For September.................................................................................................. 45 

Figure J-38: 12km Domain – North Carolina 1-hour (top) And 8-hour (bottom) Scatter Plots For 

May ....................................................................................................................................... 47 

Figure J-39: 12km Domain – North Carolina 1-hour (top) And 8-hour (bottom) Scatter Plots For 

June ....................................................................................................................................... 48 

Figure J-40: 12km Domain – North Carolina 1-hour (top) And 8-hour (bottom) Scatter Plots For 

July........................................................................................................................................ 49 
Figure J-41; 12km Domain – North Carolina 1-hour (top) And 8-hour (bottom) Scatter Plots For 

August ................................................................................................................................... 50 

Figure J-42: 12km Domain – North Carolina 1-hour (top) And 8-hour (bottom) Scatter Plots For 

September ............................................................................................................................. 51 

Figure J-43: 12km Domain – South Carolina 1-hour (top) And 8-hour (bottom) Scatter Plots For 

May ....................................................................................................................................... 53 

Figure J-44: 12km Domain – South Carolina 1-hour (top) And 8-hour (bottom) Scatter Plots For 

June ....................................................................................................................................... 54 

Figure J-45: 12km Domain – South Carolina 1-hour (top) And 8-hour (bottom) Scatter Plots For 

July........................................................................................................................................ 55 

Figure J-46: 12km Domain – South Carolina 1-hour (top) And 8-hour (bottom) Scatter Plots For 

August ................................................................................................................................... 56 

Figure J-47: 12km Domain – South Carolina 1-hour (top) And 8-hour (bottom) Scatter Plots For 

September ............................................................................................................................. 57 

Figure J-48: Arrowood 1-hour (top) And 8-hour (bottom) Scatter Plots For May Through 

September ............................................................................................................................. 59 

Figure J-49: County Line 1-hour (top) And 8-hour (bottom) Scatter Plots For May Through 

September ............................................................................................................................. 60 

Figure J-50: Crouse 1-hour (top) And 8-hour (bottom) Scatter Plots For May Through 

September ............................................................................................................................. 61 

Figure J-51: Garinger 1-hour (top) And 8-hour (bottom) Scatter Plots For May Through 

September ............................................................................................................................. 62 

Figure J-52: Enochville 1-hour (top) And 8-hour (bottom) Scatter Plots For May Through 

September ............................................................................................................................. 63 

Figure J-53: Monroe 1-hour (top) And 8-hour (bottom) Scatter Plots For May Through 

September ............................................................................................................................. 64 

Figure J-54: Rockwell 1-hour (top) And 8-hour (bottom) Scatter Plots For May Through 

September ............................................................................................................................. 65 

Figure J-55: York, SC 1-hour (top) And 8-hour (bottom) Scatter Plots For May Through 

September ............................................................................................................................. 66 

Figure J-56: 12km Domain – VISTAS/ASIP States Only 1-hour (top) And 8-hour (bottom) 

Time Series Plots For May.................................................................................................... 68 

Figure J-57: 12km Domain – VISTAS/ASIP States Only 1-hour (top) And 8-hour (bottom) 

Time Series Plots For June.................................................................................................... 69 

Figure J-58: 12km Domain – VISTAS/ASIP States Only 1-hour (top) And 8-hour (bottom) 

Time Series Plots For July .................................................................................................... 70 

Figure J-59: 12km Domain – VISTAS/ASIP States Only 1-hour (top) And 8-hour (bottom) 

Time Series Plots For August ............................................................................................... 71 

Figure J-60: 12km Domain – VISTAS/ASIP States Only 1-hour (top) And 8-hour (bottom) 

Time Series Plots For September.......................................................................................... 72 

Figure J-61: 12km Domain – North Carolina 1-hour (top) And 8-hour (bottom) Time Series 

Plots For May........................................................................................................................ 74 
Figure J-62: 12km Domain – North Carolina 1-hour (top) And 8-hour (bottom) Time Series 

Plots For June........................................................................................................................ 75 

Figure J-63: 12km Domain – North Carolina 1-hour (top) And 8-hour (bottom) Time Series 

Plots For July ........................................................................................................................ 76 

Figure J-64: 12km Domain – North Carolina 1-hour (top) And 8-hour (bottom) Time Series 

Plots For August ................................................................................................................... 77 

Figure J-65: 12km Domain – North Carolina 1-hour (top) And 8-hour (bottom) Time Series 

Plots For September.............................................................................................................. 78 

Figure J-66: 12km Domain – South Carolina 1-hour (top) And 8-hour (bottom) Time Series 

Plots For May........................................................................................................................ 80 

Figure J-67: 12km Domain – South Carolina 1-hour (top) And 8-hour (bottom) Time Series 

Plots For June........................................................................................................................ 81 

Figure J-68: 12km Domain – South Carolina 1-hour (top) And 8-hour (bottom) Time Series 

Plots For July ........................................................................................................................ 82 

Figure J-69: 12km Domain – South Carolina 1-hour (top) And 8-hour (bottom) Time Series 

Plots For August ................................................................................................................... 83 

Figure J-70: 12km Domain – South Carolina 1-hour (top) And 8-hour (bottom) Time Series 

Plots For September.............................................................................................................. 84 

Figure J-71: Arrowood 1-hour (top) And 8-hour (bottom) Time Series Plots For May.............. 86 

Figure J-72: Arrowood 1-hour (top) And 8-hour (bottom) Time Series Plots For June.............. 87 

Figure J-73: Arrowood 1-hour (top) And 8-hour (bottom) Time Series Plots For July .............. 88 

Figure J-74: Arrowood 1-hour (top) And 8-hour (bottom) Time Series Plots For August ......... 89 

Figure J-75: Arrowood 1-hour (top) And 8-hour (bottom) Time Series Plots For September.... 90 

Figure J-76: County Line 1-hour (top) And 8-hour (bottom) Time Series Plots For May.......... 91 

Figure J-77: County Line 1-hour (top) And 8-hour (bottom) Time Series Plots For June.......... 92 

Figure J-78: County Line 1-hour (top) And 8-hour (bottom) Time Series Plots For July........... 93 

Figure J-79: County Line 1-hour (top) And 8-hour (bottom) Time Series Plots For August...... 94 

Figure J-80: County Line1-hour (top) And 8-hour (bottom) Time Series Plots For September . 95 

Figure J-81: Crouse 1-hour (top) And 8-hour (bottom) Time Series Plots For May................... 96 

Figure J-82: Crouse 1-hour (top) And 8-hour (bottom) Time Series Plots For June................... 97 

Figure J-83: Crouse 1-hour (top) And 8-hour (bottom) Time Series Plots For July ................... 98 

Figure J-84: Crouse 1-hour (top) And 8-hour (bottom) Time Series Plots For August .............. 99 

Figure J-85: Crouse 1-hour (top) And 8-hour (bottom) Time Series Plots For September....... 100 

Figure J-86: Enochville 1-hour (top) And 8-hour (bottom) Time Series Plots For May........... 101 

Figure J-87: Enochville 1-hour (top) And 8-hour (bottom) Time Series Plots For June........... 102 

Figure J-88: Enochville 1-hour (top) And 8-hour (bottom) Time Series Plots For July ........... 103 

Figure J-89: Enochville 1-hour (top) And 8-hour (bottom) Time Series Plots For August ...... 104 

Figure J-90: Enochville 1-hour (top) And 8-hour (bottom) Time Series Plots For September. 105 

Figure J-91: Garinger 1-hour (top) And 8-hour (bottom) Time Series Plots For May.............. 106 

Figure J-92: Garinger 1-hour (top) And 8-hour (bottom) Time Series Plots For June.............. 107 

Figure J-93: Garinger 1-hour (top) And 8-hour (bottom) Time Series Plots For July .............. 108 
Figure J-94: Garinger 1-hour (top) And 8-hour (bottom) Time Series Plots For August.......... 109 

Figure J-95: Garinger 1-hour (top) And 8-hour (bottom) Time Series Plots For September.... 110 

Figure J-96: Monroe 1-hour (top) And 8-hour (bottom) Time Series Plots For May ............... 111 

Figure J-97: Monroe 1-hour (top) And 8-hour (bottom) Time Series Plots For June ............... 112 

Figure J-98: Monroe 1-hour (top) And 8-hour (bottom) Time Series Plots For July................ 113 

Figure J-99: Monroe 1-hour (top) And 8-hour (bottom) Time Series Plots For August ........... 114 

Figure J-100: Monroe 1-hour (top) And 8-hour (bottom) Time Series Plots For September.... 115 

Figure J-101: Rockwell 1-hour (top) And 8-hour (bottom) Time Series Plots For May........... 116 

Figure J-102: Rockwell 1-hour (top) And 8-hour (bottom) Time Series Plots For June........... 117 

Figure J-103: Rockwell 1-hour (top) And 8-hour (bottom) Time Series Plots For July ........... 118 

Figure J-104: Rockwell 1-hour (top) And 8-hour (bottom) Time Series Plots For August ...... 119 

Figure J-105: Rockwell 1-hour (top) And 8-hour (bottom) Time Series Plots For September. 120 

Figure J-106: York, SC 1-hour (top) And 8-hour (bottom) Time Series Plots For May........... 121 

Figure J-107: York, SC 1-hour (top) And 8-hour (bottom) Time Series Plots For June........... 122 

Figure J-108: York, SC 1-hour (top) And 8-hour (bottom) Time Series Plots For July............ 123 

Figure J-109: York, SC 1-hour (top) And 8-hour (bottom) Time Series Plots For August....... 124 

Figure J-110: York, SC 1-hour (top) And 8-hour (bottom) Time Series Plots For September . 125 
LIST OF TABLES 

Table J-1: VISTAS/ASIP Phase II Initial CMAQ Model Configuration. ..................................... 1 

Table J-2: Statistical Metric Calculations...................................................................................... 4 

Table J-3: 12km Domain Model Statistics for 1-Hour Ozone....................................................... 5 

Table J-4: 12km Domain Model Statistics for 8-Hour Ozone....................................................... 6 

Table J-5: Metrolina Region and Monitor Statistics for 1-Hour Ozone ........................................ 7 

Table J-6: Metrolina Region and Monitor Statistics for 8-Hour Ozone ........................................ 7 
1 

MODEL PERFORMANCE EVALUATION 

I. Air Quality Modeling 

The air quality modeling for the Charlotte-Gastonia-Rock Hill, NC-SC 8-hour ozone 

nonattainment area (referred to as the Metrolina area) was performed in conjunction with the regional 

haze modeling being done by the Southeast Regional Planning Organization, Visibility Improvement 

State and Tribal Association of the Southeast (VISTAS) and the fine particulate matter (PM2.5) and 

ozone modeling being done by the Association of Southeastern Integrated Planning (ASIP). VISTAS and 

ASIP are run by the ten Southeast states (Alabama, Florida, Georgia, Kentucky, Mississippi, North 

Carolina, South Carolina, Tennessee, Virginia and West Virginia. Since the regional haze and PM2.5 

modeling uses annual simulations and includes an intermediate year that is the attainment year required 

for the Metrolina nonattainment area, the North Carolina Division of Air Quality (NCDAQ) decided to 

use the this modeling for its attainment demonstration. 

A. Air Quality Model Configuration 

This air quality modeling system used in this State Implementation Plan (SIP) modeling exercise 

was the US Environmental Protection Agency’s (USEPA’s) Models-3/ Community Multiscale Air 

Quality (CMAQ). The configuration of the CMAQ modeling system was chosen based on the results of 

the model sensitivity testing performed in Phase I of the VISTAS/ASIP regional haze, fine particulate,

and ozone modeling efforts. This configuration of options is identical to those used in Phase II of the 

VISTAS/ASIP projects. The Phase II CMAQ configuration is presented in Table J-1. The 36/12 

kilometer (km) horizontal and vertical grid system used in the VISTAS/ASIP Phase II modeling is 

displayed in Figure J-1. 
1 

Table J-1: VISTAS/ASIP Phase II Initial CMAQ Model Configuration. 

Model Option Phase II CMAQ Configuration

Model Version Version 4.5 (September 2003) 

Horizontal Resolution 36/12 km 

No. Vertical Layers NZ = 19 

Horizontal Advection PPM 

Vertical Advection PPM 

Horizontal Diffusion Spatially Varying 

Vertical Diffusion KV (Eddy Diffusion) 

Minimum Vertical Diffusivity 1.0 m2/s 

MM5 Configuration Pleim-Xiu/ACM No linkage of 5-day run segments 

MM5 Processing MCIP2.2 Pass Through 

Gas-Phase Chemistry CB4 

Gas-Phase Chemistry Solver MEBI 

Secondary Organic Aerosol SORGAM 

Aqueous-Phase Chemistry RADM 

Aerosol Chemistry AE3/ISORROPIA 

Dry Deposition Pleim-Xiu 

Plume-in-Grid Off 

Initial Concentrations Default with 13-15 day spin-up 

Boundary Conditions 2001 Seasonal GEOS-CHEM 

Emissions 2002 Emissions 
2 

Figure J-1 CMAQ nested 12 km grid in the CMAQ 36 km grid. Lower left x, y of the 36 km grid is 

at -2736000, -20880000 

B. Secondary Organic Aerosols Modifications 

As a part of the Phase II modeling project, the VISTAS/ASIP air quality modeling contractors 

developed modifications to the Secondary Organic Aerosols (SOA) subroutines inside of the CMAQ 

modeling system to improve modeled particulate matter and visibility performance. Since the modeling 

activities in this SIP exercise took a “one atmosphere” approach identical to that of VISTAS/ASIP, the

CMAQ SOA modifications are included as part of this ozone modeling. 
3 

II. Model Performance Statistics 

To quantify model performance, several statistical measures were calculated and evaluated for the 

VISTAS/ASIP states combined, for North Carolina, for South Carolina, and individually for each of the 

Metrolina area ozone monitors. The statistical measures selected were based on the recommendations 

outlined in section 18.4.1 of the USEPA’s Guidance On The Use Of Models And Other Analyses for 

Demonstrating Attainment of Air Quality Goals for Ozone, PM2.5, and Regional Haze (“Attainment 

Guidance”). 

The statistical measures were calculated for both 1-hour and 8-hour ozone concentrations and 

based only on the respective portion of the 12km modeling domain. A customary 60 parts per billion 

(ppb) cutoff threshold was applied in the statistical calculations. This cutoff threshold prevents very low 

ozone concentrations from being included in the model performance statistics and generally prevents a 

widely known overnight over prediction of minimal ozone concentrations from biasing the performance 

evaluation of the modeling when ozone concentrations are much higher and of the most concern. 

For convenience, these statistical measures or metrics along with a variety of additional statistical 

measures are summarized in Table J-2. 
4 

Table J-2: Statistical Metric Calculations 

Statistical Measure Shorthand 

Notation 

Mathematical Expression Notes 

Accuracy of Paired 

Peak 

Ap

peak

peak

O

P − O

Coefficient of 

Determination 

 R2

( )( )

∑ ∑

∑

= =

=

− −













− −

N

i

N

i

i i

N

i

i i

P P O O

P P O O

1 1

2 2

2

1

( ) ( )

Pi= prediction at time and 

 location i; 

Oi = observation at time and 

 location i; 

P = arithmetic average of Pi, 

 i = 1, 2, . . ., N; 

O = arithmetic average of Oi, 

 i = 1, 2, . . ., N; 

Normalized Mean 

Error 

NME 

∑

∑

=

=

−

N

i

i

N

i

i i

O

P O

1

1

Reported as % 

Root Mean Square 

Error 

RMSE 

( ) 2

1

1

1 2













∑ −

=

N

i

Pi Oi

N

Reported as % 

Fractional Gross 

Error 

FError 

∑= +

−

N

i i i

i i

P O

P O

N 1

2

Reported as % 

Mean Absolute 

Gross Error 

MAGE ∑=

−

N

i

Pi Oi

N 1

1

Mean Normalized 

Gross Error 

MNGE 

∑=

N −

i i

i i

O

P O

N 1

1

Reported as % 

Mean Biased MB ∑( )

=

−

N

i

Pi Oi

N 1

1 Reported as concentration 

Mean Normalized 

Bias 

MNB ( ) ∑=

−

N

i i

i i

O

P O

N 1

1 Reported as % 

Mean Fractionalized 

Bias (Fractional 

Bias) 

MFB 

∑=

















+

−

N

i i i

i i

P O

P O

N 1

2

Reported as % 

Normalized Mean 

Bias 

NMB ( )

∑

∑

=

=

−

N

i

i

N

i

i i

O

P O

1

1

Reported as % 

Bias Factor BF 

∑=

















N

i i

i

O

P

N 1

1

Reported as BF:1 or 1:BF or in 

fractional notation (BF/1 or 1/BF) 
5 

A. 12km Domain Statistics – Selected Regions 

The statistical data calculated for the VISTAS/ASIP region, the North Carolina, and the South 

Carolina portions of the 12-km domain are presented in Table J-3 for 1-hour ozone and Table J-4 for 8-

hour ozone. On the whole, all of the statistical measures or metrics were within generally accepted ranges 

for mean bias, mean normalized bias, and mean normalized gross error. There was a slight under 

prediction of 1-hour and 8-hour ozone concentrations. This under prediction was noted in all months and 

across the VISTAS/ASIP states as a whole and also individually across North Carolina and across South 

Carolina. The most noted under prediction of ozone was contained in the months of August and 

September. In these months, the mean normalized bias fell slightly below the suggested range of ± 5-15 

percent. The NCDAQ does not believe this slight under prediction for August and September impacts the

overall results for this SIP modeling exercise. In all cases, the mean normalized gross error was 

significantly below the 30-35 percent range at the 60 ppb threshold for all regions. These 1-hour and 8-

hour statistical metrics were used as a first screening of the model performance. 

Table J-3: 12km Domain Model Statistics for 1-Hour Ozone 

Region / Month Modeled

Mean (ppb)

Observed

Mean (ppb)

Mean Bias

(ppb)

Mean

Normalized

Bias (%)

Mean

Normalized

Gross Error

(%)

May 62.54 69.08 -6.53 -8.92 13.64

June 63.75 73.45 -9.7 -12.67 15.81

July 64.20 73.70 -9.5 -12.16 16.70

August 62.95 75.35 -12.4 -15.78 18.49

September 62.19 74.68 -12.49 -16.20 18.52

Mean (May-Sept) 63.13 73.25 -10.12 -13.15 16.63

May 64.68 70.24 -5.56 -7.53 12.74

June 63.65 74.39 -10.74 -13.97 15.89

July 64.54 75.51 -10.97 -13.71 16.61

August 62.34 76.92 -14.59 -18.24 19.59

September 59.83 71.64 -11.81 -16.08 18.10

Mean (May-Sept) 63.01 73.74 -10.73 -13.91 16.59

May 64.39 69.37 -4.98 -6.72 11.69

June 62.99 73.33 -10.34 -13.36 15.33

July 61.61 72.73 -11.12 -14.54 16.72

August 61.05 74.13 -13.08 -17.20 18.34

September 62.23 75.24 -13.01 -16.69 18.34

Mean (May-Sept) 62.45 72.96 -10.51 -13.70 16.08

12km ASIP States Combined

North Carolina

South Carolina

1-Hour Model Performance Statistics (BaseG2A - 60 ppb Cutoff)
6 

Table J-4: 12km Domain Model Statistics for 8-Hour Ozone 

B. Metrolina Nonattainment Area and Monitor Statistics 

As a further exploration of modeling performance, specifically in the Metrolina region, similar 

1 hour (Table J-5) and 8-hour (Table J-6) statistical measures were calculated for the region as a whole 

and for each of the ozone monitors in this region. In just the Metrolina region, the mean bias, mean 

normalized bias, and mean normalized gross error were all within recommended and accepted ranges. A 

slight under prediction of 1-hour and 8-hour ozone was also observed at this more refined level of 

analysis and was similar to what was seen at the larger state and VISTAS/ASIP region levels. Individual 

monthly statistics are not presented here due to the very limited number of modeled and observed data 

pairs at just the eight Metrolina ozone monitoring sites. Whole season statistics were more representative 

of how this air quality modeling will be applied in the modeled attainment test discussed in Appendix L. 

Across the whole season, the Metrolina region as a whole and all of the ozone monitoring sites had mean 

normalized bias statistics in the suggested ± 5-15 percent range and mean normalized gross error statistics 

in the suggested 30-35 percent range given a 60 ppb threshold. 

Region / Month Modeled

Mean (ppb)

Observed

Mean (ppb)

Mean Bias

(ppb)

Mean

Normalized

Bias (%)

Mean

Normalized

Gross Error

(%)

May 61.26 67.69 -6.44 -8.96 12.47

June 62.62 70.99 -8.37 -11.37 14.02

July 62.73 70.85 -8.12 -10.90 14.74

August 61.33 72.57 -11.24 -14.92 16.98

September 60.81 71.98 -11.17 -14.98 17.07

Mean (May-Sept) 61.75 70.82 -9.07 -12.23 15.06

May 64.06 69.05 -5 -6.86 10.76

June 62.21 71.82 -9.62 -13.03 14.47

July 62.94 72.10 -9.16 -12.09 14.63

August 60.60 73.92 -13.33 -17.40 18.34

September 57.90 69.37 -11.46 -16.11 17.68

Mean (May-Sept) 61.54 71.25 -9.71 -13.10 15.18

May 63.87 67.71 -3.85 -5.31 9.66

June 61.95 70.92 -8.97 -12.10 13.52

July 60.89 70.24 -9.35 -12.73 14.75

August 59.77 71.39 -11.62 -16.03 16.64

September 61.18 72.62 -11.44 -15.22 16.32

Mean (May-Sept) 61.53 70.58 -9.05 -12.28 14.18

North Carolina

South Carolina

12km ASIP States Combined

8-Hour Model Performance Statistics (BaseG2A - 60 ppb Cutoff)
7 

Table J-5: Metrolina Region and Monitor Statistics for 1-Hour Ozone 

Table J-6: Metrolina Region and Monitor Statistics for 8-Hour Ozone 

Monitor Site AIRS ID Modeled

Mean (ppb)

Observed

Mean (ppb)

Mean Bias

(ppb)

Mean

Normalized

Bias (%)

Mean

Normalized

Gross Error

(%)

Metrolina Region 66.75 74.75 -8.125 -9.850 14.716

Crouse 37-109-0004 69.0 75.0 -6.0 -6.748 12.016

Garinger 37-119-0041 65.0 75.0 -10.0 -13.152 17.750

Arrowood 37-119-1005 69.0 74.0 -5.0 -5.901 14.137

County Line 37-119-1009 69.0 75.0 -7.0 -8.046 13.746

Rockwell 37-159-0021 66.0 75.0 -9.0 -10.930 14.320

Enochville 37-159-0022 68.0 76.0 -9.0 -10.229 14.488

Monroe 37-179-0003 63.0 74.0 -11.0 -13.436 16.347

York, SC 45-091-0006 65.0 74.0 -8.0 -10.356 14.922

1-Hour Model Performance Statistics (BaseG2A - 60 ppb Cutoff)

Monitor Site AIRS ID Modeled

Mean (ppb)

Observed

Mean (ppb)

Mean Bias

(ppb)

Mean

Normalized

Bias (%)

Mean

Normalized

Gross Error

(%)

Metrolina Region 65.25 73.00 -7.875 -10.152 13.289

Crouse 37-109-0004 69.0 73.0 -4.0 -5.330 9.868

Garinger 37-119-0041 63.0 73.0 -11.0 -14.470 16.125

Arrowood 37-119-1005 67.0 72.0 -5.0 -5.837 12.249

County Line 37-119-1009 67.0 74.0 -7.0 -8.807 11.885

Rockwell 37-159-0021 65.0 73.0 -9.0 -10.989 13.322

Enochville 37-159-0022 65.0 75.0 -9.0 -11.790 13.710

Monroe 37-179-0003 62.0 72.0 -10.0 -13.097 14.958

York, SC 45-091-0006 64.0 72.0 -8.0 -10.898 14.197

8-Hour Model Performance Statistics (BaseG2A - 60 ppb Cutoff)
8 

III. Spatial Plots 

The 12km domain spatial plots of modeled 1-hour and 8-hour maximum ozone concentrations for 

2002, with the actual ozone observations overlaid are presented in this section. These plots are magnified 

or zoomed with respect to North Carolina. Only the days used in calculating the relative reduction factor 

(RRF) calculation at the Metrolina monitoring sites are presented here. The first plot on the page is the 1-

hour maximum ozone, followed by the 8-hour maximum ozone plot. The color scale moves from lower 

concentrations in shade of blue to warmer colors for higher ozone concentrations. The scale loosely 

approximated the Air Quality Index (AQI) color scale for the 8-hour standard but was set to best 

demonstrate the gradient of ozone across North Carolina and Northern South Carolina, and to best 

highlight the range of observed ozone concentrations. 

Overall, the air quality model does well with the spatial extent of the higher ozone concentrations. The 

model does slightly under-predict the 1-hour max and 8-hour max ozone concentration, as was seen in the 

model performance statistic earlier in this Appendix. The plots show North Carolina and South 

Carolina’s higher ozone concentrations generally coincide with the major urbanized areas and with the 

major highways running through the states. The urban core of the city of Charlotte, North Carolina is

well represented in the air quality model. This is important as the highest monitoring values occur at the 

urban sites (i.e. Garinger, County Line, and Enochville). 
9 

Figure J-2: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For May 24, 2002 
10 

Figure J-3: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For May 25, 2002 
11 

Figure J-4: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For May 26, 2002 
12 

Figure J-5: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For June 1, 2002 
13 

Figure J-6: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For June 2, 2002 
14 

Figure J-7: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For June 3, 2002 
15 

Figure J-8: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For June 9, 2002 
16 

Figure J-9: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For June 10, 2002 
17 

Figure J-10: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For June 11, 2002 
18 

Figure J-11: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For June 12, 2002 
19 

Figure J-12: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For June 13, 2002 
20 

Figure J-13: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For July 1, 2002 
21 

Figure J-14: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For July 2, 2002 
22 

Figure J-15: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For July 3, 2002 
23 

Figure J-16: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For July 4, 2002 
24 

Figure J-17: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For July 5, 2002 
25 

Figure J-18: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For July 6, 2002 
26 

Figure J-19: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For July 8, 2002 
27 

Figure J-20: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For July 9, 2002 
28 

Figure J-21: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For July 16, 2002 
29 

Figure J-22: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For July 17, 2002 
30 

Figure J-23: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For July 18, 2002 
31 

Figure J-24: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For July 21, 2002 
32 

Figure J-25: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For August 1, 2002 
33 

Figure J-26: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For August 2, 2002 
34 

Figure J-27: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For August 5, 2002 
35 

Figure J-28: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For August 10, 2002 
36 

Figure J-29: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For August 11, 2002 
37 

Figure J-30: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For August 12, 2002 
38 

Figure J-31: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For August 21, 2002 
39 

Figure J-32: Modeled Predicted And Observed Peak 1-hour (top) And 8-hour (bottom) Ozone 

Concentrations Spatial Plots For August 23, 2002 
40 

IV. Scatter Plots 

Scatter plots of modeled predicted daily maximum ozone versus observed daily maximum ozone 

are presented in this section. There are scatter plots for both 1-hour and 8-hour ozone concentrations. As 

with the previous model performance statistics, scatter plots were created for the VISTAS/ASIP region of 

the 12km modeling domain, for North Carolina, for South Carolina, and individually for each of the 

ozone monitors in the Metrolina region. At the VISTAS/ASIP regional and the two individual state 

levels, monthly scatter plots are presented across the entire summer season of May through September. 

For the individual ozone monitoring sites, only the scatter plots for the entire summer season are 

displayed due to the limited nature of the dataset.

On each page, the top image is the 1-hour daily maximum ozone scatter plot and the bottom image is the

8-hour daily maximum ozone scatter plot for the respective month or season and the respective region or 

monitoring site. 

A. 12km Domain Scatter Plots – VISTAS/ASIP States Only 

From the whole VISTAS/ASIP region perspective, thousands of data points are presented in the 

1-hour and 8-hour ozone scatter plots (Figure J-33 through Figure J-37). These data points include 

modeled and observed ozone concentrations at numerous urban, suburban, and rural ozone monitoring 

sites. Across this 10 state VISTAS/ASIP region, there are a greater frequency of urban and suburban sites 

represented in these scatter plots. Even with such a wide variety of monitoring site locations, the model 

and observed values tend to correlated reasonable well, as most of the data points are clustered along the 

1:1 line across the full range of data. The under prediction of observed ozone concentrations previously 

discussed in this Appendix is most notable in these scatter plots when observed ozone concentrations are 

in excess of 120 ppb. 

There are not any systematic abnormalities found in either the 1-hour or 8-hour scatter plots for 

the VISTAS/ASIP region of the 12km modeling domain. This confirms the acceptable model 

performance statistics presented earlier in this Appendix. 
41 

Figure J-33: 12km Domain – VISTAS/ASIP States Only 1-hour (top) And 8-hour (bottom) Scatter 

Plots For May 
42 

Figure J-34: 12km Domain – VISTAS/ASIP States Only 1-hour (top) And 8-hour (bottom) Scatter 

Plots For June 
43 

Figure J-35: 12km Domain – VISTAS/ASIP States Only 1-hour (top) And 8-hour (bottom) Scatter 

Plots For July 
44 

Figure J-36: 12km Domain – VISTAS/ASIP States Only 1-hour (top) And 8-hour (bottom) Scatter 

Plots For August 
45 

Figure J-37: 12km Domain – VISTAS/ASIP States Only 1-hour (top) And 8-hour (bottom) Scatter 

Plots For September 
46 

B. 12km Domain Scatter Plots – North Carolina 

The 1-hour and 8-hour ozone scatter plots for just North Carolina are presented in this subsection. 

The North Carolina scatter plots for May through September are found in Figure J-38 through Figure J-42 

on the following pages. There is a good mixture of urban, suburban, and rural ozone monitoring sites 

contained in these scatter plots. With this heterogeneous mixture of sites, the model and observed values 

are well correlated and tightly clustered along the 1:1 line across the majority of the data pairs. Under 

predictions of observed ozone can be seen when observed ozone concentrations are greater than 100 ppb 

and are most notable in the few cases that observed ozone surpasses 120 ppb. 

There are not any systematic abnormalities found in either the 1-hour or 8-hour scatter plots for 

the North Carolina portion of the 12km modeling domain. This further confirms the reasonable model 

performance statistics presented earlier in this Appendix. 
47 

Figure J-38: 12km Domain – North Carolina 1-hour (top) And 8-hour (bottom) Scatter Plots For 

May 
48 

Figure J-39: 12km Domain – North Carolina 1-hour (top) And 8-hour (bottom) Scatter Plots For 

June 
49 

Figure J-40: 12km Domain – North Carolina 1-hour (top) And 8-hour (bottom) Scatter Plots For 

July 
50 

Figure J-41; 12km Domain – North Carolina 1-hour (top) And 8-hour (bottom) Scatter Plots For 

August 
51 

Figure J-42: 12km Domain – North Carolina 1-hour (top) And 8-hour (bottom) Scatter Plots For 

September 
52 

C. 12km Domain Scatter Plots – South Carolina 

The 1-hour and 8-hour ozone scatter plots for just South Carolina are presented in this subsection. 

The South Carolina scatter plots for May through September are found on the following pages (Figure J43 through Figure J-47). South Carolina has a slightly higher frequency of suburban and rural ozone 

monitoring sites. Even with a lower frequency of urban ozone monitoring sites than across the 

VISTAS/ASIP region or across North Carolina, these scatter plots continue to demonstrate very 

reasonable correlations between model and observed ozone concentrations. Under predictions of 

observed ozone can be seen when observed ozone concentrations are at the higher end of the scale, but 

there are relatively few observations of ozone that surpass 120 ppb where more notable under predictions 

were seen in the previous VISTAS/ASIP and North Carolina regional scatter plots. 

There are not any systematic abnormalities found in either the 1-hour or 8-hour scatter plots for 

the South Carolina portion of the 12km modeling domain. This further confirms the reasonable model 

performance statistics presented earlier in this Appendix. 
53 

Figure J-43: 12km Domain – South Carolina 1-hour (top) And 8-hour (bottom) Scatter Plots For 

May 
54 

Figure J-44: 12km Domain – South Carolina 1-hour (top) And 8-hour (bottom) Scatter Plots For 

June 
55 

Figure J-45: 12km Domain – South Carolina 1-hour (top) And 8-hour (bottom) Scatter Plots For 

July 
56 

Figure J-46: 12km Domain – South Carolina 1-hour (top) And 8-hour (bottom) Scatter Plots For 

August 
57 

Figure J-47: 12km Domain – South Carolina 1-hour (top) And 8-hour (bottom) Scatter Plots For 

September 
58 

D. Metrolina Monitor Specific Scatter Plots 

The 1-hour and 8-hour ozone scatter plots for the individual ozone monitoring sites in the 

Metrolina region are presented in this subsection. The Metrolina monitor specific scatter plots for the 

entire summer season of May through September are found in Figure J-48 through Figure J-55 on the 

following pages. Of these 8 monitoring sites, the majority of the sites are either urban or suburban. With 

a more urbanized observed dataset, the respective monitor scatter plots show excellent correlation of 

model and observed ozone concentrations across the entire range of data. Under predictions of higher 

observed ozone concentrations can still be seen in these scatter plots, but these under predictions are 

significantly less notable than in any of the previous 1-hour or 8-hour ozone scatter plots presented in this 

section. 

There are not any systematic abnormalities found in either the 1-hour or 8-hour scatter plots for 

the individual ozone monitoring sites in the Metrolina region. This is a strong indication that the model 

performance statistics presented earlier in this Appendix are sound and that these modeling results are 

appropriate for further use in the modeled attainment test. 
59 

1-hour Ozone Scatter Plot - Site: Arrowood

AIRS ID: 37-119-1005

0

0.02

0.04

0.06

0.08

0.1

0.12

0 0.02 0.04 0.06 0.08 0.1 0.12

Observed Ozone (PPM)

Modeled Ozone (PPM)

8-hour Ozone Scatter Plot - Site: Arrowood

AIRS ID: 37-119-1005

0

0.02

0.04

0.06

0.08

0.1

0.12

0 0.02 0.04 0.06 0.08 0.1 0.12

Observed Ozone (PPM)

Modeled Ozone (PPM)

Figure J-48: Arrowood 1-hour (top) And 8-hour (bottom) Scatter Plots For May Through 

September 
60 

1-hour Ozone Scatter Plot - Site: County Line

AIRS ID: 37-119-1009

0

0.02

0.04

0.06

0.08

0.1

0.12

0 0.02 0.04 0.06 0.08 0.1 0.12

Observed Ozone (PPM)

Modeled Ozone (PPM)

8-hour Ozone Scatter Plot - Site: County Line

AIRS ID: 37-119-1009

0

0.02

0.04

0.06

0.08

0.1

0.12

0 0.02 0.04 0.06 0.08 0.1 0.12

Observed Ozone (PPM)

Modeled Ozone (PPM)

Figure J-49: County Line 1-hour (top) And 8-hour (bottom) Scatter Plots For May Through 

September 
61 

1-hour Ozone Scatter Plot - Site: Crouse

AIRS ID: 37-109-0004

0

0.02

0.04

0.06

0.08

0.1

0.12

0 0.02 0.04 0.06 0.08 0.1 0.12

Observed Ozone (PPM)

Modeled Ozone (PPM)

8-hour Ozone Scatter Plot - Site: Crouse

AIRS ID: 37-109-0004

0

0.02

0.04

0.06

0.08

0.1

0.12

0 0.02 0.04 0.06 0.08 0.1 0.12

Observed Ozone (PPM)

Modeled Ozone (PPM)

Figure J-50: Crouse 1-hour (top) And 8-hour (bottom) Scatter Plots For May Through September 
62 

1-hour Ozone Scatter Plot - Site: Garinger

AIRS ID: 37-119-0041

0

0.02

0.04

0.06

0.08

0.1

0.12

0 0.02 0.04 0.06 0.08 0.1 0.12

Observed Ozone (PPM)

Modeled Ozone (PPM)

8-hour Ozone Scatter Plot - Site: Garinger

AIRS ID: 37-119-0041

0

0.02

0.04

0.06

0.08

0.1

0.12

0 0.02 0.04 0.06 0.08 0.1 0.12

Observed Ozone (PPM)

Modeled Ozone (PPM)

Figure J-51: Garinger 1-hour (top) And 8-hour (bottom) Scatter Plots For May Through 

September 
63 

1-hour Ozone Scatter Plot - Site: Enochville

AIRS ID: 37-159-0022

0

0.02

0.04

0.06

0.08

0.1

0.12

0 0.02 0.04 0.06 0.08 0.1 0.12 Observed Ozone (PPM)

Modeled Ozone (PPM)

8-hour Ozone Scatter Plot - Site: Enochville

AIRS ID: 37-159-0022

0

0.02

0.04

0.06

0.08

0.1

0.12

0 0.02 0.04 0.06 0.08 0.1 0.12

Observed Ozone (PPM)

Modeled Ozone (PPM)

Figure J-52: Enochville 1-hour (top) And 8-hour (bottom) Scatter Plots For May Through 

September 
64 

1-hour Ozone Scatter Plot - Site: Monroe

AIRS ID: 37-179-0003

0

0.02

0.04

0.06

0.08

0.1

0.12

0 0.02 0.04 0.06 0.08 0.1 0.12

Observed Ozone (PPM)

Modeled Ozone (PPM)

8-hour Ozone Scatter Plot - Site: Monroe

AIRS ID: 37-179-0003

0

0.02

0.04

0.06

0.08

0.1

0.12

0 0.02 0.04 0.06 0.08 0.1 0.12

Observed Ozone (PPM)

Modeled Ozone (PPM)

Figure J-53: Monroe 1-hour (top) And 8-hour (bottom) Scatter Plots For May Through September 
65 

1-hour Ozone Scatter Plot - Site: Rockwell

AIRS ID: 37-159-0021

0

0.02

0.04

0.06

0.08

0.1

0.12

0 0.02 0.04 0.06 0.08 0.1 0.12

Observed Ozone (PPM)

Modeled Ozone (PPM)

8-hour Ozone Scatter Plot - Site: Rockwell

AIRS ID: 37-159-0021

0

0.02

0.04

0.06

0.08

0.1

0.12

0 0.02 0.04 0.06 0.08 0.1 0.12

Observed Ozone (PPM)

Modeled Ozone (PPM)

Figure J-54: Rockwell 1-hour (top) And 8-hour (bottom) Scatter Plots For May Through 

September 
66 

1-hour Ozone Scatter Plot - Site: York, SC

AIRS ID: 45-091-0006

0

0.02

0.04

0.06

0.08

0.1

0.12

0 0.02 0.04 0.06 0.08 0.1 0.12

Observed Ozone (PPM)

Modeled Ozone (PPM)

8-hour Ozone Scatter Plot - Site: York, SC

AIRS ID: 45-091-0006

0

0.02

0.04

0.06

0.08

0.1

0.12

0 0.02 0.04 0.06 0.08 0.1 0.12

Observed Ozone (PPM)

Modeled Ozone (PPM)

Figure J-55: York, SC 1-hour (top) And 8-hour (bottom) Scatter Plots For May Through 

September 
67 

V. Time Series 

The time series plots of hourly model predicted ozone (green line) and hourly observed ozone 

(black stars) are presented in this section. There are time series plots for both 1-hour and 8-hour ozone 

concentrations for each of the months from May through September. Time series plots were created for 

the VISTAS/ASIP region of the 12km modeling domain, for North Carolina, for South Carolina, and 

individually for each of the ozone monitors in the Metrolina region. 

On each page, the 1-hour ozone time series plot is presented first (top) and the 8-hour ozone time 

series plots is present second (bottom) for the respective month and the respective region or monitoring 

site. 

A. 12 km Domain Time Series Plots – VISTAS/ASIP States Only 

Overall the air quality model does an excellent job at capturing the diurnal pattern for both 1-hour 

and 8-hour ozone (Figure J-56 through Figure J-60). The model tends to over predict the minimum ozone

values over the course of the May through September time frame, but this is expected given the well 

known issue of air quality models generally not capturing the absolute overnight ozone minimums very 

well. This overnight over prediction of ozone is not expected to cause any issues with the application of 

the modeled attainment test as these lower ozone concentrations are not considered in this test. There is a 

slight under prediction of peak ozone values once you reach the core of the ozone season (June, July, and 

August). Despite this slight under prediction of the ozone peaks, several high ozone episodes and the

subsequent clean out events are well captured by the modeling. This is a good indication that both the 

meteorological and air quality models are representing the large synoptic weather and air quality patterns 

well throughout the duration of this summer season.
68 

 Figure J-56: 12km Domain – VISTAS/ASIP States Only 1-hour (top) And 8-hour (bottom) Time 

Series Plots For May 
69 

 

Figure J-57: 12km Domain – VISTAS/ASIP States Only 1-hour (top) And 8-hour (bottom) Time 

Series Plots For June 
70 

 

Figure J-58: 12km Domain – VISTAS/ASIP States Only 1-hour (top) And 8-hour (bottom) Time 

Series Plots For July 
71 

 

Figure J-59: 12km Domain – VISTAS/ASIP States Only 1-hour (top) And 8-hour (bottom) Time 

Series Plots For August 
72 

 

Figure J-60: 12km Domain – VISTAS/ASIP States Only 1-hour (top) And 8-hour (bottom) Time 

Series Plots For September 
73 

B. 12 km Domain Time Series Plots – North Carolina

From just the North Carolina perspective, the air quality model continues to do an excellent job at 

capturing the diurnal pattern for both 1-hour and 8-hour ozone (Figures J-61 through J-65). As with the 

VISTAS/ASIP region, the model under predicts the peak ozone values at times throughout the summer 

season as well as the overnight over prediction issue previously discussed. In particular, a portion of the 

month of May and the last few days of August and September show a more notable under prediction of 

the afternoon peak ozone concentrations. Overall, the air quality model continues to capture the various 

synoptic weather and air quality cycles quite well and is within acceptable tolerances for model 

performance. 
74 

Figure J-61: 12km Domain – North Carolina 1-hour (top) And 8-hour (bottom) Time Series Plots 

For May 
75 

 

Figure J-62: 12km Domain – North Carolina 1-hour (top) And 8-hour (bottom) Time Series Plots 

For June 
76 

 

Figure J-63: 12km Domain – North Carolina 1-hour (top) And 8-hour (bottom) Time Series Plots 

For July 
77 

 

Figure J-64: 12km Domain – North Carolina 1-hour (top) And 8-hour (bottom) Time Series Plots 

For August 
78 

Figure J-65: 12km Domain – North Carolina 1-hour (top) And 8-hour (bottom) Time Series Plots 

For September 
79 

C. 12 km Domain Time Series Plots – South Carolina

For South Carolina, the air quality model does an excellent job at capturing the diurnal pattern for 

both 1-hour and 8-hour ozone (Figures J-66 through J-70). The model under predicts the peak ozone 

values at times throughout the summer season as well as the overnight over prediction issue previously

discussed. As with the North Carolina time series analysis, a portion of the month of May and the last 

few days of August and September show a more notable under prediction of the afternoon peak ozone 

concentrations. Overall, the air quality model continues to capture the various synoptic weather and air 

quality cycles quite well and is within acceptable tolerances for model performance. 
80 

Figure J-66: 12km Domain – South Carolina 1-hour (top) And 8-hour (bottom) Time Series Plots 

For May 
81 

 

Figure J-67: 12km Domain – South Carolina 1-hour (top) And 8-hour (bottom) Time Series Plots 

For June 
82 

 

Figure J-68: 12km Domain – South Carolina 1-hour (top) And 8-hour (bottom) Time Series Plots 

For July 
83 

 

Figure J-69: 12km Domain – South Carolina 1-hour (top) And 8-hour (bottom) Time Series Plots 

For August 
84 

 

Figure J-70: 12km Domain – South Carolina 1-hour (top) And 8-hour (bottom) Time Series Plots 

For September 
85 

D. Metrolina Monitor Specific Time Series Plots 

Finally, the time series for the individual ozone monitoring sites in the Metrolina region are 

present in Figures J-71 through J-110 on the following pages. There are 8 monitoring sites with 5 months 

presented for a total of 40 pages of 1-hour and 8-hour times series 

As with the larger domain time series plots and analyses presented earlier in this section, the air 

quality model tends to slightly under predict peak 1-hour and 8-hour ozone values. The over prediction of 

the nighttime minimum issue is more noticeable in the individual monitoring site time series, especially 

this more urbanized collection of sites due to the higher night time nitrogen oxide (NOx) environment 

found in such a metropolitan region. The NOx emissions titrate the ozone after sunset and the ozone 

levels decrease dramatically. The air quality model does not replicate this type of phenomenon very well. 

Again, the nighttime minimum over prediction is not an issue with respect to the modeled attainment test 

and is not of significant concern in this modeling exercise. The ability of the air quality model to very 

accurately capture the synoptic cycles from high ozone episodes to very clean periods is best 

demonstrated in these individual monitor time series. Based on all of the data presented in these time 

series plots, NCDAQ concludes that the air quality modeling continues to meet all requirements for 

further application in the modeled attainment test.
86 

Monitor: Arrowood (37-119-1005) 

Month: May 

 Figure J-71: Arrowood 1-hour (top) And 8-hour (bottom) Time Series Plots For May 
87 

Monitor: Arrowood (37-119-1005) 

Month: June

 Figure J-72: Arrowood 1-hour (top) And 8-hour (bottom) Time Series Plots For June 
88 

Monitor: Arrowood (37-119-1005) 

Month: July 

 Figure J-73: Arrowood 1-hour (top) And 8-hour (bottom) Time Series Plots For July 
89 

Monitor: Arrowood (37-119-1005) 

Month: August 

 Figure J-74: Arrowood 1-hour (top) And 8-hour (bottom) Time Series Plots For August 
90 

Monitor: Arrowood (37-119-1005) 

Month: September 

 Figure J-75: Arrowood 1-hour (top) And 8-hour (bottom) Time Series Plots For September 
91 

Monitor: County Line (37-119-1009) 

Month: May 

 Figure J-76: County Line 1-hour (top) And 8-hour (bottom) Time Series Plots For May 
92 

Monitor: County Line (37-119-1009) 

Month: June 

 Figure J-77: County Line 1-hour (top) And 8-hour (bottom) Time Series Plots For June 
93 

Monitor: County Line (37-119-1009) 

Month: July 

 Figure J-78: County Line 1-hour (top) And 8-hour (bottom) Time Series Plots For July 
94 

Monitor: County Line (37-119-1009) 

Month: August 

 Figure J-79: County Line 1-hour (top) And 8-hour (bottom) Time Series Plots For August 
95 

Monitor: County Line (37-119-1009) 

Month: September 

 Figure J-80: County Line1-hour (top) And 8-hour (bottom) Time Series Plots For September 
96 

Monitor: Crouse (37-109-0004) 

Month: May 

 Figure J-81: Crouse 1-hour (top) And 8-hour (bottom) Time Series Plots For May 
97 

Monitor: Crouse (37-109-0004) 

Month: June 

 Figure J-82: Crouse 1-hour (top) And 8-hour (bottom) Time Series Plots For June 
98 

Monitor: Crouse (37-109-0004) 

Month: July 

 Figure J-83: Crouse 1-hour (top) And 8-hour (bottom) Time Series Plots For July 
99 

Monitor: Crouse (37-109-0004) 

Month: August 

 Figure J-84: Crouse 1-hour (top) And 8-hour (bottom) Time Series Plots For August 
100 

Monitor: Crouse (37-109-0004) 

Month: September 

 Figure J-85: Crouse 1-hour (top) And 8-hour (bottom) Time Series Plots For September 
101 

Monitor: Enochville (37-159-0022) 

Month: May 

 Figure J-86: Enochville 1-hour (top) And 8-hour (bottom) Time Series Plots For May 
102 

Monitor: Enochville (37-159-0022) 

Month: June 

 Figure J-87: Enochville 1-hour (top) And 8-hour (bottom) Time Series Plots For June 
103 

Monitor: Enochville (37-159-0022) 

Month: July 

 Figure J-88: Enochville 1-hour (top) And 8-hour (bottom) Time Series Plots For July 
104 

Monitor: Enochville (37-159-0022) 

Month: August 

 Figure J-89: Enochville 1-hour (top) And 8-hour (bottom) Time Series Plots For August 
105 

Monitor: Enochville (37-159-0022) 

Month: September 

 Figure J-90: Enochville 1-hour (top) And 8-hour (bottom) Time Series Plots For September 
106 

Monitor: Garinger (37-119-0041) 

Month: May 

 Figure J-91: Garinger 1-hour (top) And 8-hour (bottom) Time Series Plots For May 
107 

Monitor: Garinger (37-119-0041) 

Month: June 

 Figure J-92: Garinger 1-hour (top) And 8-hour (bottom) Time Series Plots For June 
108 

Monitor: Garinger (37-119-0041) 

Month: July 

 Figure J-93: Garinger 1-hour (top) And 8-hour (bottom) Time Series Plots For July 
109 

Monitor: Garinger (37-119-0041) 

Month: August 

 Figure J-94: Garinger 1-hour (top) And 8-hour (bottom) Time Series Plots For August 
110 

Monitor: Garinger (37-119-0041) 

Month: September 

 Figure J-95: Garinger 1-hour (top) And 8-hour (bottom) Time Series Plots For September 
111 

Monitor: Monroe (37-179-0003) 

Month: May 

 Figure J-96: Monroe 1-hour (top) And 8-hour (bottom) Time Series Plots For May 
112 

Monitor: Monroe (37-179-0003) 

Month: June 

 Figure J-97: Monroe 1-hour (top) And 8-hour (bottom) Time Series Plots For June 
113 

Monitor: Monroe (37-179-0003) 

Month: July 

 Figure J-98: Monroe 1-hour (top) And 8-hour (bottom) Time Series Plots For July 
114 

Monitor: Monroe (37-179-0003) 

Month: August 

 Figure J-99: Monroe 1-hour (top) And 8-hour (bottom) Time Series Plots For August 
115 

Monitor: Monroe (37-179-0003) 

Month: September 

 Figure J-100: Monroe 1-hour (top) And 8-hour (bottom) Time Series Plots For September 
116 

Monitor: Rockwell (37-159-0021) 

Month: May 

 Figure J-101: Rockwell 1-hour (top) And 8-hour (bottom) Time Series Plots For May 
117 

Monitor: Rockwell (37-159-0021) 

Month: June 

 Figure J-102: Rockwell 1-hour (top) And 8-hour (bottom) Time Series Plots For June 
118 

Monitor: Rockwell (37-159-0021) 

Month: July 

 Figure J-103: Rockwell 1-hour (top) And 8-hour (bottom) Time Series Plots For July 
119 

Monitor: Rockwell (37-159-0021) 

Month: August 

 Figure J-104: Rockwell 1-hour (top) And 8-hour (bottom) Time Series Plots For August 
120 

Monitor: Rockwell (37-159-0021) 

Month: September 

 Figure J-105: Rockwell 1-hour (top) And 8-hour (bottom) Time Series Plots For September 
121 

Monitor: York, SC (45-091-0006) 

Month: May 

 Figure J-106: York, SC 1-hour (top) And 8-hour (bottom) Time Series Plots For May 
122 

Monitor: York, SC (45-091-0006) 

Month: June 

 Figure J-107: York, SC 1-hour (top) And 8-hour (bottom) Time Series Plots For June 
123 

Monitor: York, SC (45-091-0006) 

Month: July 

 Figure J-108: York, SC 1-hour (top) And 8-hour (bottom) Time Series Plots For July 
124 

Monitor: York, SC (45-091-0006) 

Month: August 

 Figure J-109: York, SC 1-hour (top) And 8-hour (bottom) Time Series Plots For August 
125 

Monitor: York, SC (45-091-0006) 

Month: September 

Figure J-110: York, SC 1-hour (top) And 8-hour (bottom) Time Series Plots For September