APPENDIX E 1999 BASE CASE DEVELOPMENT AND PERFORMANCE ANALYSES SAN ANTONIO EAC REGION ATTAINMENT DEMONSTRATION MARCH 2004 E 2 Appendix E Table of Contents Page Introduction                               . E 9 Model Inputs                                E 11 Land Use Data                          .. E 11 Dry Deposition Algorithms                       E 11 Chemistry Data                          .. E 14 Boundary and Initial Conditions                   . E 14 CAMx Model Options                         E 17 September 13 20, 1999 Photochemical Model Performance          . E 17 Model Performance: 1 Hour Average Ozone Concentrations      .. E 18 Ozone Metrics                       .. E 18 Time Series Plots                      . E 32 Scatter Plots                        . E 35 Weekend/ Weekday Comparisons               . E 37 Model Performance: 8 Hour Average Ozone Concentrations        E 39 Ozone Metrics                       .. E 39 Graphic Analyses                      . E 70 Scatter/ Q Q Plots                  .. E 70 Tile Plots                      .. E 74 Diagnostic Evaluations                     E 78 Zero out Runs: Urban Areas              . E 78 Incremental Removal of VOC and NOx Precursors    .. E 79 Comparisons between UT Austin and AACOG 1999 Base Cases        . E 83 References                               .. E 85 E 3 Appendix E List of Tables Page Table E 1 Meteorological and Emissions Inputs to CAMx Photochemical Model Test Runs                      .. E 12 Table E 2 Summary of Chemistry Data for the September 13 20, 1999 CAMx Model                        . E 14 Table E 3 Boundary and Initial Conditions used by in the Original Model and the Final Model used by San Antonio and Austin for their Early Action Compacts                      .. E 16 Table E 4 Summary of Options for the September 13 20, 1999 CAMx Model.. E 17 Table E 5 1 hour Statistics for CAMS 3, September 13   20, 1999      E 20 Table E 6 1 hour Statistics for CAMS 38, September 13   20, 1999      E 20 Table E 7 1 hour Statistics for Austin Monitors ( CAMS 3 & 38), September 13   20, 1999                        . E 20 Table E 8 1 hour Statistics for CAMS 23, September 13   20, 1999     . E 20 Table E 9 1 hour Statistics for CAMS 58, September 13   20, 1999     . E 21 Table E 10 1 hour Statistics for CAMS 59, September 13   20, 1999     . E 21 Table E 11 1 hour Statistics for CAMS 678, September 13   20, 1999    .. E 21 Table E 12 1 hour Statistics for San Antonio Monitors ( CAMS 23, 58, 59 & 678) September 13   20, 1999                    E 21 Table E 13 1 hour Statistics for CAMS 62, September 13   20, 1999     . E 22 Table E 14 1 hour Statistics for CAMS 601, September 13   20, 1999     E 22 Table E 15 1 hour Statistics for Central Texas Monitors ( CAMS 3, 23, 38, 58, 59, 62, 601, & 678) September 13   20, 1999          . E 22 Table E 16 1 hour Statistics for Corpus Christi ( CAMS 4 & 21), September 13   20, 1999                         E 22 Table E 17 1 hour Statistics for CAMS 87, September 13   20, 1999     . E 23 Table E 18 8 hour Statistics for CAMS 3, September 13   20, 1999      E 40 Table E 19 8 hour Statistics for CAMS 38, September 13   20, 1999     . E 40 Table E 20 8 hour Statistics for Austin Downwind Monitors ( CAMS 3 & 38), September 13   20, 1999                    E 41 Table E 21 8 hour Statistics for CAMS 23, September 13   20, 1999     . E 41 Table E 22 8 hour Statistics for CAMS 58, September 13   20, 1999     . E 41 Table E 23 8 hour Statistics for CAMS 59, September 13   20, 1999     . E 41 Table E 24 8 hour Statistics for CAMS 678, September 13   20, 1999     E 42 Table E 25 8 hour Statistics for San Antonio Downwind Monitors ( CAMS 23 & 58), September 13   20, 1999               . E 42 Table E 26 8 hour Statistics for San Antonio Upwind Monitors ( CAMS 59 & 678), September 13   20, 1999               . E 42 Table E 27 8 hour Statistics for all San Antonio Monitors ( CAMS 23, 58, 59, & 678), September 13   20, 1999              E 42 Table E 28 8 hour Statistics for CAMS 601, September 13   20, 1999     E 43 Table E 29 8 hour Statistics for CAMS 62, September 13   20, 1999     . E 43 Table E 30 8 hour Statistics for Central Texas Downwind Monitors ( CAMS 3, 23, 38, 58) September 13   20, 1999               E 43 Table E 31 8 hour Statistics for Central Texas Upwind Monitors ( CAMS 59, 62, 601, 678), September 13   20, 1999            .. E 43 E 4 Appendix E List of Tables ( continued) Page Table E 32 8 hour Statistics for Central Texas ( CAMS 3, 23, 38, 58, 59, 62, 601, 678), September 13   20, 1999            . E 44 Table E 33 8 hour Statistics for Corpus Christi Monitors ( CAMS 4 & 21), September 13   20, 1999                  .. E 44 Table E 34 8 hour Statistics for CAMS 87, September 13   20, 1999     . E 44 Table E 35 Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for CAMS 3, September 13   20, 1999     E 47 Table E 36 Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for CAMS 38, September 13   20, 1999    . E 48 Table E 37 Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for Austin Monitors   CAMS 3 & 38, September 13   20, 1999                    E 49 Table E 38 Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for CAMS 23, September 13   20, 1999    . E 50 Table E 39 Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for CAMS 58, September 13   20, 1999    . E 51 Table E 40 Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for CAMS 59, September 13   20, 1999    . E 52 Table E 41 Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for CAMS 678, September 13   20, 1999    E 53 Table E 42 Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for San Antonio Downwind Monitors ( CAMS 23 & 58), September 13   20, 1999            E 54 Table E 43 Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for San Antonio Upwind Monitors ( CAMS 59 & 678), September 13   20, 1999               . E 55 Table E 44 Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for San Antonio Monitors ( CAMS 23, 58, 59 & 678), September 13   20, 1999               . E 56 Table E 45 Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for CAMS 62, September 13   20, 1999     E 57 Table E 46 Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for CAMS 601, September 13   20, 1999    E 58 Table E 47 Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for Central Texas Downwind Monitors ( CAMS 3, 23, 38, 58), September 13   20, 1999          E 59 Table E 48 Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for Central Texas Upwind Monitors ( CAMS 59, 62, 601, 678), September 13   20, 1999            . E 60 Table E 49 Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for Central Texas Monitors ( CAMS 3, 23, 38, 58, 59, 62, 601, 678), September 13   20, 1999       .. E 61 Table E 50 Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for Corpus Christi Monitors   CAMS 4 & 21, September 13   20, 1999                    E 62 E 5 Appendix E List of Tables ( continued) Page Table E 51 Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for CAMS 87, September 13   20, 1999    . E 63 Table E 52 Comparison of Predicted Peak 8 hour Concentrations for Final UT and AACOG Base Case Runs             E 84 E 6 Appendix E List of Figures Page Figure E 1 Nested Grid System for the 1999 South Texas Photochemical Model Simulation                      .. E 9 Figure E 2 Long term Palmer Drought Severity Index for September 18, 1999. E 13 Figure E 3 Map Showing the Delineation of Boundary Segments for the Photochemical Model used by Austin and San Antonio for their Early Action Compacts                     E 17 Figure E 4 1 hour Unpaired Peak Accuracy, CAMS 23, September 13   20, 1999                             E 23 Figure E 5 1 hour Unpaired Peak Accuracy, CAMS 58, September 13   20, 1999                             E 24 Figure E 6 1 hour Unpaired Peak Accuracy, Central Texas Monitors ( CAMS 3, 23, 38, 58, 59, 62, 601, 678), September 13   20, 1999     E 24 Figure E 7 1 hour Average Paired Peak Accuracy at CAMS 23, September 13 20, 1999                          E 25 Figure E 8 1 hour Average Paired Peak Accuracy at CAMS 58, September 13 20, 1999                          E 25 Figure E 9 1 hour Average Paired Peak Accuracy at Central Texas Monitors ( CAMS 3, 23, 38, 58, 59, 62, 601, 678), September 13 20, 1999   E 26 Figure E 10 1 hour Normalized Bias, CAMS 23, September 13   20, 1999   . E 26 Figure E 11 1 hour Normalized Bias, CAMS 58, September 13   20, 1999   . E 27 Figure E 12 1 hour Normalized Bias, Central Texas Monitors ( CAMS 3, 23, 38, 58, 59, 62, 601, 678), September 13   20, 1999       . E 27 Figure E 13 1 hour Normalized Error, CAMS 23, September 13   20, 1999    E 28 Figure E 14 1 hour Normalized Error, CAMS 58, September 13   20, 1999    E 28 Figure E 15 1 hour Normalized Error, Central Texas Monitors ( CAMS 3, 23, 38, 58, 59, 62, 601, 678), September 13   20, 1999       . E 29 Figure E 16 1 hour Timing Bias at CAMS 23, September 13   20, 1999     E 29 Figure E 17 1 hour Timing Bias at CAMS 58, September 13   20, 1999     E 30 Figure E 18 1 hour Timing Bias at Central Texas Monitors ( CAMS 3, 23, 38, 58, 59, 62, 601, 678), September 13   20, 1999         . E 30 Figure E 19 1 hour Fractional Bias at CAMS 23, September 13   20, 1999    E 31 Figure E 20 1 hour Fractional Bias at CAMS 58, September 13   20, 1999    E 31 Figure E 21 1 hour Fractional Bias at Central Texas Monitors ( CAMS 3, 23, 38, 58, 59, 62, 601, 678, September 13   20, 1999         E 32 Figure E 22 Observed versus Predicted 1 hour Average Ozone Concentrations at CAMS 23, September 13   20, 1999              E 33 Figure E 23 Observed versus Predicted 1 hour Average Ozone Concentrations at CAMS 58, September 13   20, 1999              E 33 Figure E 24 Observed versus Predicted 1 hour Average Ozone Concentrations at CAMS 59, September 13   20, 1999              E 34 Figure E 25 Observed versus Predicted 1 hour Average Ozone Concentrations at CAMS 678, September 13   20, 1999            . E 34 Figure E 26 Scatter Plot of 1 hour Observed/ Predicted Data Pairs at CAMS 23. E 35 Figure E 27 Scatter Plot of 1 hour Observed/ Predicted Data Pairs at CAMS 58. E 35 Figure E 28 Scatter Plot of 1 hour Observed/ Predicted Data Pairs at CAMS 59. E 36 Figure E 29 Scatter Plot of 1 hour Observed/ Predicted Data Pairs at CAMS 678                            .. E 36 E 7 Appendix E List of Figures ( continued) Page Figure E 30 Comparison of Observed/ predicted 1 hour Concentrations at CAMS 23 and Daily NOx EI for Bexar County, September 13   20, 1999                         . E 37 Figure E 31 Comparison of Observed/ predicted 1 hour Concentrations at CAMS 58 and Daily NOx EI for Bexar County, September 13   20, 1999                          E 38 Figure E 32 Comparison of Observed/ predicted 1 hour Concentrations at Four San Antonio CAMS and Daily NOx EI for Bexar County, September 13   20, 1999                    E 38 Figure E 33 Normalized Bias for Downwind, Upwind, and Coastal Monitors Calculated using Method 1, September 13 20, 1999        E 64 Figure E 34 Normalized Bias for Downwind, Upwind, and Coastal Monitors Calculated using Method 2, September 13 20, 1999      . E 65 Figure E 35 Normalized Bias for Downwind, Upwind, and Coastal Monitors Calculated using Method 3, September 13 20, 1999        E 66 Figure E 36 Fractional Bias for Downwind, Upwind, and Coastal Monitors Calculated using Method 1, September 13 20, 1999        E 67 Figure E 37 Fractional Bias for Downwind, Upwind, and Coastal Monitors Calculated using Method 2, September 13 20, 1999        E 68 Figure E 38 Fractional Bias for Downwind, Upwind, and Coastal Monitors Calculated using Method 3, September 13 20, 1999        E 69 Figure E 39 Scatter / Q Q Plots for CAMS 23 Calculated using Three Methodologies                       .. E 71 Figure E 40 Scatter / Q Q Plots for CAMS 58 Calculated using Three Methodologies                        E 72 Figure E 41 Scatter / Q Q Plots for the Eight Central Texas Monitors ( CAMS 3, 23, 38, 58, 59, 62, 601, 678) Calculated using Three Methodologies                        E 73 Figure E 42 Predicted Daily Maximum 8 hour Ozone Concentrations within the 4 km Subdomain for Wednesday, September 15, 1999       E 75 Figure E 43 Predicted Daily Maximum 8 hour Ozone Concentrations within the 4 km Subdomain for Thursday, September 16, 1999      .. E 75 Figure E 44 Predicted Daily Maximum 8 hour Ozone Concentrations within the 4 km Subdomain for Friday, September 17, 1999        .. E 76 Figure E 45 Predicted Daily Maximum 8 hour Ozone Concentrations within the 4 km Subdomain for Saturday, September 18, 1999       . E 76 Figure E 46 Predicted Daily Maximum 8 hour Ozone Concentrations within the 4 km Subdomain for Sunday, September 19, 1999         E 77 Figure E 47 Predicted Daily Maximum 8 hour Ozone Concentrations within the 4 km Subdomain for Monday, September 20, 1999       .. E 77 Figure E 48 Predicted Reduction in Ozone Concentrations (%) in the SAER after Removing Austin, Corpus Christi, and Houston Anthropogenic NOx and VOC Emissions from the Photochemical Model       .. E 79 Figure E 49 Predicted Ozone Concentrations at CAMS 23 after Removing Local ( 4 county SAER) NOx and VOC Emissions from Simulation 17b, September 15, 1999                    E 80 E 8 Appendix E List of Figures ( continued) Page Figure E 50 Predicted Ozone Concentrations at CAMS 23 after Removing Local ( 4 county SAER) NOx and VOC Emissions from Simulation 17b, September 16, 1999                    E 81 Figure E 51 Predicted Ozone Concentrations at CAMS 23 after Removing Local ( 4 county SAER) NOx and VOC Emissions from Simulation 17b, September 17, 1999                    E 81 Figure E 52 Predicted Ozone Concentrations at CAMS 23 after Removing Local ( 4 county SAER) NOx and VOC Emissions from Simulation 17b, September 18, 1999                    E 82 Figure E 53 Predicted Ozone Concentrations at CAMS 23 after Removing Local ( 4 county SAER) NOx and VOC Emissions from Simulation 17b, September 19, 1999                    E 82 Figure E 54 Predicted Ozone Concentrations at CAMS 23 after Removing Local ( 4 county SAER) NOx and VOC Emissions from Simulation 17b, September 20, 1999                    E 83 E 9 INTRODUCTION The elevated ozone episode that occurred between September 15   20, 1999 in Southcentral Texas was modeled using the Comprehensive Air quality Model with extensions ( CAMx). This is an alternative model for developing air quality simulations in accordance with EPA's ( On line, no date) report, Summary Descriptions of Alternative Air Quality Models. CAMx is a Eulerian photochemical grid model that makes use of a two way nested grid structure, with the coarsest grid ( 36 km) covering a wide regional domain, a 12 km grid that incorporates Eastern Texas including the nonattainment areas of Dallas/ Fort Worth, Houston/ Galveston, and Beaumont/ Port Arthur, and a fine grid ( 4 km) extending over four Texas near nonattainment areas as shown in figure E 1.

Figure: E 1. Nested Grid System for the 1999 South Texas Photochemical Model Simulation. E 10 The original September 1999 simulation was developed by ENVIRON International Corporation and documented in their report Development of a Joint CAMx Photochemical Modeling Database for the Four Southern Texas Near Non Attainment Areas ( Emery, Tai, Wilson, and Yarwood, 2002). Their final and best performing run ( developed without arbitrary meteorological or emissions inputs), labeled CAMx Run 13, produced promising results. However, CAMx Run 13 exhibited some problems that were prevalent in earlier simulations, including consistent under predictions of maximum and mean ozone concentrations. ENVIRON staff recommended performing comprehensive QA/ QC procedures on model settings and inputs, particularly meteorological and emissions inputs, and incorporating refinements to the model where appropriate.

ENVIRON and the University of Texas at Austin conducted extensive analyses of the meteorological model used as CAMx input for the September 1999 episode. Development of the original meteorological model, labeled Met 3c, was described in ENVIRON's report ( Emery et al., 2002). As a product of the QA/ QC analyses conducted by the ENVIRON/ UT team, numerous improvements were made to the meteorological model. Some revised runs, including Met 6f and Met 5d, attenuated, although not necessarily eliminated, certain problems associated with Met 3c, including over prediction of wind speeds at night and under predictions during the daytime and over prediction of early morning temperatures. Most of the refinements the ENVIRON/ UT team incorporated into the meteorological model are documented in the report Revised Meteorological Modeling of the September 13 20, 1999 Texas Ozone Episode ( Emery, Tai, McGaughey, and Allen, 2003). Development of the meteorological model used as input to the final photochemical model run, labeled Met 5g, is described in appendix B of the SAER SIP revision.

Emissions inputs were also reviewed and refined for the September 1999 baseline simulation. One of the most significant refinements made to the 1999 modeling EI was use of MOBILE6 to estimate on road emissions for some urban counties in Texas. MOBILE6 was not available when the original September 1999 model was created. Texas Transportation Institute, under contract with the TCEQ, recalculated on road files for 18 NNA counties, including Bexar County, using the newly released MOBILE6 model. The original MOBILE6 file, referred to as version 1, was later refined to incorporate an improved methodology to account for heavy duty diesel vehicle VMT. The refined MOBILE6 on road file for the 18 NNA counties is labeled version 2. ( See Appendix C for a detailed description of TTI's on road estimation methodology.) In addition to enhanced mobile on road estimations, the State provided AACOG with refined EIs for specific geographic locations including other NNA areas ( Austin, Corpus Christi and Victoria), Houston, and the remainder of the State of Texas. 1 AACOG was also provided a refined point source file ( TCEQ 2003), which contained additional VOC emissions for Houston, to account for the results of a study conducted as part of the TexAQS 2000 project. However, staff decided to omit the revised Houston point source file in the final 1999 baseline simulation for several reasons. First, a sensitivity run ( CAMx Run 17c) in which the file was included as model input indicated 1 The updated Texas EI was developed for the 2000 Houston attainment SIP and includes refined area and non road emission estimations. Since the Houston EI was developed for a different time period, the emissions were backcast to September 1999 using projection ratios developed from EGAS and NONROAD models. E 11 the increased VOC emissions for Houston point sources had an insignificant impact on ozone concentrations in San Antonio during the September 1999 episode. Second, as of the timeframe when the final baseline run ( CAMx Run 18) was developed and tested, the State had yet to receive approval from the EPA to use the modified point source file in the Houston attainment demonstration SIP. Third, the refined VOC database did not include a 2007 projection. Using the refined data for only the 1999 base case would create inconsistencies in the treatment of the base case and projection case EIs. And fourth, the modified EI was designed for a 2000 episode, not 1999.

Table E 1 provides a description of the meteorological and emissions inputs to the final set of sensitivity and baseline runs conducted for the September episode beginning with the first 1999 base case submitted by ENVIRON, CAMx Run 13, through development of the final baseline run, CAMx Run 18.

MODEL INPUTS Methodologies used to develop the major inputs to the photochemical model are described in detail in appendix B Development of the 1999 Meteorological Model, Appendix C On Road Mobile Emissions Inventory Development, and appendix D 1999 Base Case Modeling Emissions Inventory Development of the SAER attainment demonstration SIP. This appendix focuses on development of other inputs to the model simulation and selection of CAMx model options. The following sections on development/ determination of land use data, dry deposition algorithms, chemistry data, boundary/ initial conditions, and CAMx model options were provided by The University of Texas at Austin and ENVIRON ( September 17, 2003) in their draft report Development of the September 13 20, 1999 Base Case Photochemical Model for Austin's Early Action Compact. Except where noted, these sections focus on model inputs and options for the final baseline run, CAMx Run 18.

Land Use Data ENVIRON ( Jimenez et al., 2002) developed land use grid data to characterize surface boundary conditions for the September 1999 episode. This information was developed from the same data used to generate spatial emission surrogates. ENVIRON created software to process the raw spatial surrogate data into the eleven land use categories used by CAMx, to grid the data to the 36, 12, and 4km CAMx grids, and to write the results in an appropriate format for input to CAMx.

Dry Deposition Algorithms Dry deposition algorithms in CAMx are based on the regional scale deposition model developed by Wesely et al. ( 1989). These algorithms have been widely used in both field applications and air quality models.

ENVIRON and UT reviewed the Palmer drought severity index, shown in figure E 2 for eastern Texas and found a moderate level of drought stress during the episode. Although the MM5 models accounted for reduced soil moisture, the original dry deposition algorithm in the September 13 20, 1999 CAMx model did not account for vegetation moisture stress. Because of the potential influence of drought stress on the uptake of pollutants through plant stomata and the importance of dry deposition as a E 12 Table E 1. Meteorological and Emissions Inputs to CAMx Photochemical Model Test Runs.

CAMx Run: Run 13 Run 13b Run 13c Run 13d Run 13e Run 14 Run 15 Run 16 Run 17 Run 17b Run 17c Run 17d Run 18 Met 3c           Met 3c + Increased Mixing layer   Mer 6f   Met 5d     Met 5g           Updated Texas EI         Updated Austin EI         Updated 2007 Regional EI*   Updated Victoria's EI   BC/ IC 60               Mobile5                 Mobile6 version 1       Mobile6 version 1x1.4**   Mobile6 version 2 ( VMT Upgrade)   Modified dry deposition               Additional VOC from Houston's Point Sources   * The Austin, Corpus Christi, San Antonio, and Victoria portions of the August 2000 Texas EI were removed from the model and replaced with refined area specific September 1999 emissions for those areas. For the remainder of the State, the August 2000 Texas EI was backcast to September 1999.

** Version 1x1.4 is a sensitivity run conducted prior to receiving the MOBILE6 version 2 EI file. It was employed to test the anticipated impact of increasing HDD VMT ( Version 2) by multiplying HDD VMT by 1.4 ( increasing HDD VMT by 40%). E 13 physical removal process for ozone and other secondary pollutants, ENVIRON initiated changes to the CAMx deposition algorithms for the September 13 20, 1999 episode.

Wesely supplies minimum bulk stomatal resistances by season and land use type. High resistances ( 9999) represent no deposition through the stomata. Vegetation moisture stress codes ( 0= unstressed; 1= stressed, 2= extremely stressed) essentially define The current formulation of Wesely's dry deposition model in CAMx can be manipulated to account for drought stress through the use of vegetation moisture stress codes. Factors by which minimum bulk stomatal resistances are increased/ decreased to reflect drought conditions: if istress = 1 then the stomatal resistance is increased by a factor of two; if istress = 2, then the stomatal resistance is increased by a factor of 10. ENVIRON increased drought stress codes over land use categories by one to reflect summer drought conditions for those land use categories that did not already have very high minimum bulk stomatal resistances. With the approval of the TCEQ and the U. S. EPA, these modifications were adopted by San Antonio and Austin for the September 13 20, 1999 photochemical model.

Figure E 2. Long term Palmer Drought Severity Index for September 18, 1999 ( NOAA Climate Prediction Center, 2003). E 14 Chemistry Data Chemistry data, developed by ENVIRON ( Emery et al., 2002) for the September 1999 episode, are summarized in Table E 2.

Table E 2. Summary of Chemistry Data for the September 13 20, 1999 CAMx Model. Input Data/ Specification Description Chemistry Parameters CB4 with current radical termination reactions and isoprene mechanism Photolysis rates TUV version 4 Albedo/ Haze/ Ozone File   Surface UV albedo from land use grid data   Total ozone column data from satellite data from the Total Ozone Mapping Spectrometer ( TOMS)   Haze optical depth field assumed spatially and temporally constant at 0.1.

Boundary and Initial Conditions A number of sensitivity studies focusing on boundary and initial conditions were conducted following the initial CAMx model performance evaluation of the September 13 20, 1999 episode. The results of the model performance evaluation and CAMx simulations conducted by ENVIRON suggested that the September 1999 episode was promising, but required additional refinement to improve performance. Daily peak and daily mean ozone concentrations were under predicted by 10 20% and 10 30%, respectively, at each ambient monitoring site. Although the unpaired peak accuracy and normalized gross error met EPA criteria on most days, the relative bias failed to meet EPA criteria in all near non attainment areas on at least one episode day.

EPA default boundary and initial conditions, which were used in the original modeling, are shown in the last column of Table E 3. AACOG initiated sensitivity studies that focused on increasing ozone concentrations from 40 ppb to 60 ppb along all boundaries of the 36 km domain and in the initial conditions supplied to CAMx. Model performance improved significantly and indeed, EPA performance criteria for unpaired peak accuracy, normalized bias, and gross error, were met on most days in Central Texas. The AACOG and the University of Texas, on behalf of CAPCO, then undertook a number of sensitivity studies to further elucidate the influence of boundary and initial conditions on model performance:

  Increase all boundary conditions to 60 ppb   Increase ozone concentrations along the northern and eastern boundaries from 40 ppb to 60 ppb.   Increase ozone concentrations along the northern boundary from 40 ppb to 60 ppb.   Increase ozone concentrations along the eastern boundary from 40 ppb to 60 ppb.   Increase initial ozone concentrations from 40 ppb to 60 ppb. E 15 In conjunction with the sensitivity studies, UT also examined whether the increase in ozone concentrations upwind and along the boundaries could be supported by ambient monitoring data during the episode. UT developed time series from relevant U. S. EPA AIRS monitors as well as from the IMPROVE network. In total, data from sixteen states ( Oklahoma, Kansas, Nebraska, Missouri, Iowa, Indiana, Illinois, Arkansas, West Virginia, Ohio, Kentucky, Tennessee, North Carolina, Georgia, South Carolina, Alabama) were examined. Although the sensitivity studies led to variable degrees of improvement in model performance, the ambient data did not support increasing ozone concentrations above 40 ppb along most boundaries throughout the episode. The exception was the area of domain that encompassed Tennessee and North Carolina, which experienced ozone concentrations in excess of 60 ppb on most episode days.

The TCEQ suggested that UT examine the effects of boundary and initial conditions used for the September 1993 photochemical model for Houston's State Implementation Plan on model performance. These boundary and initial conditions are currently being used for the August 13 22, 1999 episode for the Dallas/ Fort Worth area, for the Longview/ Tyler/ Marshall area, and for Oklahoma ( Yarwood, 2003).

All of the model applications described above suffered from a tendency to underpredict regional ozone levels, which prompted a review of the boundary conditions. In particular, total VOC levels of only 4.4 ppb may be too low in areas of the regional modeling domain that are over land. Boundary condition values shown in Columns 1 3 of Table E 3 were originally developed for the TCEQ's regional modeling of the September 1993 episode ( Yocke et al., 1996). These values varied by boundary segment, as shown in Figure E 3 and were based on several data sources. Concentrations along the East/ Northeastern Boundary were based on EPA's guidance for UAM modeling ( EPA, 1991) with CO reduced from 350 ppb to 200 ppb and higher biogenic VOCs ( ISOP, MEOH and ETOH) based on measurements at Kinterbish, AL for the Rural Oxidants in the Southern Environment study ( Goldan et al., 1995). Western boundary concentrations were based on EPA's UAM modeling guidance ( EPA, 1991) with CO reduced from 350 ppb to 200 ppb and were consistent with data from Niwot Ridge, CO ( Watkins et al., 1995). Southern Boundary concentrations were based on the GMAQS ( Gulf of Mexico Air Quality Study) sponsored by the Minerals Management Service ( MMS, 1995). Initial conditions were identical to those in Column 3.

UT conducted a sensitivity study using the September 1993 Houston/ Galveston boundary and initial conditions and found improved model performance for the September 13 20, 1999 episode in Central Texas. The negative bias predicted by the original model was considerably reduced, and this metric, now fell within the range of EPA performance criteria. Model performance statistics will be described in detail below, but improved ozone predictions were observed throughout the regional domain, including in the Houston/ Galveston area. Because of the significantly improved model performance and the robust technical basis of these data, Austin and San Antonio, in collaboration with the TCEQ, decided to use these boundary and initial conditions for the photochemical modeling for their Early Action Compacts. E 16 Table E 3. Boundary and Initial Conditions used by in the Original Model and the Final Model used by San Antonio and Austin for their Early Action Compacts. ( Initial conditions were identical to concentrations along the western boundary. The EAC boundary and initial conditions are identical to those used in the September 1993 Houston/ Galveston model for the State Implementation Plan.)

Species NE Boundary below 1700m ( ppb) ( EAC) West Boundary below 1700 m ( ppb) ( EAC) SE Boundary and Above 1700m ( ppb) ( EAC) Default Initial and Boundary Conditions used in original modeling*.

O3 40 40 40 40 CO 200 200 100 100 NO 0.1 0.1 0.1 0.000049 NO2 1 1 1 0.08555 HNO3 3 3 1 1.525 HNO2 0.001 0.001 0.001 0.000728 ALD2 0.555 0.555 0.05 0.1051 ETH 0.51 0.51 0.15 0.005315 HCHO 2.1 2.1 0.05 1.068 OLE 0.3 0.3 0.05 PAR 14.9 14.9 7.6 3.078 TOL 0.18 0.18 0.0786 0.006043 XYL 0.0975 0.0975 0.0688 ISOP 3.6 0.1 0.001 PAN 0.1 0.1 0.1 0.03834 H2O2 3 3 1 2.263 MEOH 8.5 0.001 0.001 ETOH 1.1 0.001 0.001 * EPA Guidance E 17 Figure E 3. Map Showing the Delineation of Boundary Segments for the Photochemical Model used by Austin and San Antonio for their Early Action Compacts.*

* below 1700 m CAMx Model Options CAMx model options, established by ENVIRON ( Emery et al., 2002), are summarized in Table E 4.

Table E 4. Summary of Options for the September 13 20, 1999 CAMx Model. Input Data/ Specification Description Advection Scheme Piece Parabolic Method ( PPM) Plume in Grid Model Selected for major NOx sources > 10 tons/ day in 4 km grid > 25 tons/ day in 12 and 36 km grids Chemical Mechanism CMC fast solver SEPTEMBER 13 20, 1999 PHOTOCHEMICAL MODEL PERFORMANCE Performance analyses were conducted on several versions of the baseline runs as a means of comparing the results of refinements made to the model. EPA recommends various types of performance tests in their 8 hour guidance: graphics, ozone metrics, precursor concentrations, observational models, weekend/ weekday comparisons, ratios E 18 of indicator species, and retrospective analyses. Analyses using observational models, ratios of indicator species, and retrospective studies were not conducted on the 1999 model, due to a lack of necessary data & tools.

For example, the use of observational models is suggested in cases where an extensive monitoring network exists and precursor and indicator species are measured using instruments with appropriate sensitivity ( EPA, 1999). During the September 1999 time period, just three regulatory ozone monitors were operational in the entire San Antonio EAC region. Also, there were no ( e. g., SO2) species being measured in the region. The sole ozone precursor monitored by San Antonio area CAMS stations was NOx: CAMS 27 located in downtown San Antonio, CAMS 59 located at Calaveras Lake in southeastern Bexar County, and CAMS 62 located northeast of San Antonio in Caldwell County. However, the NOx levels were employed for precursor concentration analyses, provided in section 3.6.3 of the Executive Summary; all other performance evaluations are provided in the sections that follow.

Model performance was evaluated using statistical and graphical metrics in accordance with EPA guidance ( 1999) for both 1 hour and 8 hour attainment demonstrations. The following sections provide the results of the 1 hour and 8 hour performance tests conducted on the final September 1999 base case, CAMx Run 18.

During the September 1999 episode, peak ozone concentrations in the SAER were measured at CAMS 23 and 58. Therefore, metrics results for these monitors are of particular interest. Because of their importance, all statistics ( 1 hour and 8 hour) for CAMS 23 and CAMS 58 are included in this appendix. Some test results ( 1 hour time series plots and 8 hour scatter and Q Q plots) for other monitors within the 4 km subdomain were omitted from this appendix for the sake of brevity. These tests/ results will be provided to the EPA and the TCEQ on compact disc with submission of this SIP revision.

Model Performance: 1 Hour Averaged Ozone Concentrations EPA recommends conducting a series of 1 hour graphical performance procedures and statistical performance tests as part of the performance evaluation process ( EPA 1991). When evaluating statistical test results, monitoring network density should be considered. Since, individually, the San Antonio and Austin area networks are sparse, statistical measurements were conducted on groups as well as individual monitors.

Ozone Metrics The 1 hour statistics were determined using a program developed by ENVIRON: " camxpost." This program calculates unpaired peak accuracy ( UPA), average paired peak accuracy ( APPA), peak timing bias ( PTB), normalized bias ( NB), fractional bias, normalized error ( NE), and fractional error ( FE). Statistical metrics and associated EPA performance criteria for 1 hour averaged ozone concentrations include Statistical Performance Measure Performance Criteria Unpaired highest prediction accuracy ± 20% Normalized bias ± 15% Gross error of all pairs > 60 ppb + 35% Average paired peak accuracy  Bias in peak timing  E 19 The results of the camxpost program are presented for each monitor and for groups of monitors ( averages for Austin monitors, San Antonio monitors, and the eight Central Texas monitors) within the 4 km subdomain in tables E 5 through E 17. Yellowhighlighted values in these tables represent statistics that fall outside EPA's performance criteria on primary episode days ( September 15   20, 1999). While it is not necessary to conduct these tests on model initialization days ( September 13 14, 1999), statistics for the initialization period are included for comparison purposes. Model initialization statistics that fall outside performance thresholds are listed in bold type. Columns where data are missing represent days in which predicted measurements were less than 60 ppb.

The 1 hour statistical results are also provided in graphic form for some monitors. Figures E 4 through E 21 present bar graphs of 1 hour statistics for CAMS 23, CAMS 58, and the averaged data for eight Central Texas monitors. Monitor numbers, monitor locations, and descriptions of monitor groups are as follows:

CAMS # Monitor Name/ Group Name Location AIRS # 3 Murchison Travis County 48 453 0014 4 Corpus Christi West Nueces County 48 355 0025 21 Corpus Christi Tuloso Nueces County 48 355 0026 23 San Antonio Northwest Bexar County 48 029 0032 38 Audubon Travis County 48 453 0020 58 Camp Bullis Bexar County 48 029 0052 59 Calaveras Lake Bexar County 48 029 0059 62 San Marcos Caldwell County 48 055 0062 87 Victoria Victoria County 48 469 0003 601 Fayette Fayette County 48 149 0001 678 CPS Pecan Valley Bexar County 48 029 0055 3, 38 Austin Monitors Travis County 23, 58, 59, 678 San Antonio Monitors Bexar County 3, 23, 38, 58, 59, 62, 601, 678 Central Texas Monitors Bexar, Caldwell, Fayette, Travis Performance statistics for the San Antonio area monitors were quite good overall, although the statistical results for CAMS 59 tended to exhibit a negative bias. Unpaired peak accuracy was also somewhat problematic, particularly at CAMS 678. When results of all four San Antonio monitors were averaged ( table E 12), all daily 1 hour statistical measurements fell within acceptable bounds with the exception of unpaired peak accuracy on September 19th.

Normalized bias was also a performance issue for the Austin area. Furthermore, when 1 hour results for the two Austin monitoring locations were averaged, the problem only improved slightly. One hour statistics for the coastal areas, Corpus Christi and Victoria, exhibited a similar negative bias.

Table E 15 provides statistical metrics for 1 hour averaged ozone concentrations in Central Texas, which includes results for the Austin, San Antonio, San Marcos, and Fayette County monitors. As demonstrated, model performance met EPA acceptance criteria for each day of the primary episode. E 20 Table E 5. 1 hour Statistics for CAMS 3, September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA N/ A N/ A 21.1% 13.1% 5.2% 5.1% 4.8% 3.2% APPA N/ A N/ A 1.5%  5.0%  9.3%  3.9%  1.7%  28.5% PTB N/ A N/ A  1 0 0 1 2 1 NB N/ A N/ A 1.2%  7.5% 15.0%  10.9%  5.2%  23.7% FB N/ A N/ A 1.1%  7.9%  16.5%  12.2%  5.8%  28.5% NE N/ A N/ A 4.2% 7.5% 15.0% 11.4% 10.2% 23.7% FE N/ A N/ A 4.1% 7.9% 16.5% 12.7% 10.6% 28.5%

Table E 6. 1 hour Statistics for CAMS 38, September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA N/ A 12.4% 13.8%  16.9%  5.4% 15.0%  3.8% 26.8% APPA N/ A  9.1%  7.2%  20.5%  12.0%  25.6% 8.9% 22.0% PTB N/ A  1  1  2 1 1 1  10 NB N/ A  7.1%  7.1%  12.8%  15.8%  19.4%  15.8%  19.4% FB N/ A  7.4%  7.6%  13.8%  18.0%  22.1%  17.7%  22.1% NE N/ A 7.1% 8.1% 12.8% 16.3% 19.4% 15.8% 19.4% FE N/ A 7.4% 8.5% 13.8% 18.4% 22.1% 17.7% 22.1%

Table E 7. 1 hour Statistics for Austin Monitors ( CAMS 3 & 38), September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA N/ A 12.4% 13.8%  16.9%  5.4%  15.0%  3.8% 3.2% APPA N/ A  9.1%  2.8%  12.7%  10.6%  14.7%  5.3%  25.2% PTB N/ A  1  1  1 1 1 2  6 NB N/ A  7.1%  4.2%  10.5%  15.5%  15.7%  11.0%  21.3% FB N/ A  7.4%  4.5%  11.3%  17.4%  17.8%  12.4%  24.8% NE N/ A 7.1% 6.7% 10.5% 15.8% 15.9% 13.3% 21.3% FE N/ A 7.4% 7.0% 11.3% 17.7% 18.0% 14.6% 24.8%

Table E 8. 1 hour Statistics for CAMS 23, September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA 1.3% 7.9% 9.0% 2.6% 15.0% 8.7% 26.3% 6.7% APPA  16.7%  12.5%  9.9%  16.7%  5.3% 3.9%  3.2%  0.3% PTB  1 0  1  3 2 1  2  3 NB  20.7%  14.3%  12.6%  21.2%  11.0%  3.2%  5.7% 6.8% FB  23.6%  15.5%  13.7%  24.5%  11.8%  3.7%  6.0% 4.6% NE 20.7% 14.3% 12.6% 21.2% 11.0% 6.7% 6.7% 19.8% FE 23.6% 15.5% 13.7% 24.5% 11.8% 7.1% 7.0% 19.2% E 21 Table E 9. 1 hour Statistics for CAMS 58, September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA 5.7% 20.8% 14.0% 15.0% 15.0% 2.6% 23.6% 13.1% APPA  12.9%  4.2%  16.1%  2.7% 0.6%  12.3% 20.1%  9.6% PTB  3  3  4  2 1 0 0  4 NB  24.5%  6.2%  9.9%  7.9% 0.9%  10.4% 4.8% 2.1% FB  28.0%  6.7%  10.5%  8.7% 0.8%  11.0% 4.2% 0.8% NE 24.5% 6.8% 9.9% 10.2% 4.7% 10.4% 9.0% 14.4% FE 28.0% 7.3% 10.5% 11.0% 4.7% 11.0% 8.6% 14.5%

Table E 10. 1 hour Statistics for CAMS 59, September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA  8.8% 14.2% 9.9% 1.4% 5.4% 32.0% 23.6% 16.6% APPA  20.7%  20.5%  27.3%  13.8%  17.8%  21.1%  17.6% 2.6% PTB 1  3 2 5 7 2 1  2 NB  23.3%  19.3%  16.8%  10.2%  10.6%  18.5%  14.4%  16.6% FB  26.5%  21.4%  18.8%  11.3%  11.6%  20.6%  15.7%  20.1% NE 23.3% 19.3% 16.8% 12.5% 11.3% 18.5% 15.4% 18.0% FE 26.5% 21.4% 18.8% 13.6% 12.3% 20.6% 16.8% 21.4%

Table E 11. 1 hour Statistics for CAMS 678, September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA  1.0% 25.3% 27.0% 14.1% 33.5% 32.0% 30.4% 5.7% APPA  7.9%  10.2%  11.3%  13.0%  1.0%  7.9%  4.6%  10.1% PTB 1  1 1  2 1 3  1  1 NB  8.2%  12.2%  9.6%  7.0% 1.6%  6.2%  5.7%  4.5% FB  8.7%  13.0%  10.2%  7.6% 1.6%  6.7%  5.9%  4.8% NE 8.2% 12.2% 9.6% 8.2% 2.7% 6.5% 5.7% 6.1% FE 8.7% 13.0% 10.2% 8.7% 2.6% 7.0% 5.9% 6.4%

Table E 12. 1 hour Statistics for San Antonio Monitors ( CAMS 23, 58, 59 & 678), September 13   20, 1999. San Antonio Monitors Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA  8.8% 7.9% 9.0% 2.6% 5.4% 2.6% 23.6% 5.7% APPA  14.6%  11.9%  16.1%  11.5%  5.9%  9.4%  1.3%  4.3% PTB  1  2  1  1 3 2  1  3 NB  19.8%  12.9%  12.9%  11.5%  5.6%  10.2%  5.7%  4.0% FB  22.4%  14.1%  14.1%  12.9%  6.1%  11.1%  6.4%  6.0% NE 19.8% 13.1% 12.9% 13.0% 8.0% 11.0% 9.6% 14.9% FE 22.4% 14.3% 14.1% 14.4% 8.5% 11.9% 10.0% 15.9% E 22 Table E 13. 1 hour Statistics for CAMS 62, September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA N/ A N/ A 21.1% 15.4% 7.7% 19.2% 22.9% 30.1% APPA N/ A N/ A  9.2% 5.3%  14.6%  11.6%  3.5% 1.2% PTB N/ A N/ A 0 1 5  11  1 0 NB N/ A N/ A  4.5% 4.9%  10.0%  11.6%  6.5% 2.6% FB N/ A N/ A  4.7% 4.5%  11.4%  12.5%  6.9% 2.6% NE N/ A N/ A 6.3% 6.5% 14.2% 11.6% 7.6% 3.3% FE N/ A N/ A 6.5% 6.3% 15.3% 12.5% 8.0% 3.2%

Table E 14. 1 hour Statistics for CAMS 601, September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA  4.5% N/ A 9.3% 29.5%  6.1% 3.6% 13.8% 24.4% APPA  18.7% N/ A  5.5% 2.0%  14.4%  10.5%  5.7% 4.0% PTB  1 N/ A  1  3 2  1  2 3 NB  18.5% N/ A  3.8%  0.9%  17.6%  11.8%  12.5%  5.8% FB  20.3% N/ A  4.1%  1.2%  19.7%  12.9%  14.5%  6.8% NE 18.5% N/ A 5.2% 6.7% 17.6% 11.9% 16.4% 10.5% FE 20.3% N/ A 5.4% 6.7% 19.7% 13.0% 18.1% 11.3%

Table E 15. 1 hour Statistics for Central Texas Monitors ( CAMS 3, 23, 38, 58, 59, 62, 601, 678), September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA  8.8% 7.9%  9.0%  16.9%  5.4%  15.0%  3.8% 5.7% APPA  15.4%  11.3%  10.6%  8.0%  9.2%  11.1%  3.1%  7.8% PTB  1  2  1  1 2  1 0  2 NB  19.5%  11.7%  8.5%  8.2%  11.0%  12.1%  8.5%  9.1% FB  22.0%  12.7%  9.2%  9.2%  12.3%  13.4%  9.6%  11.2% NE 19.5% 11.9% 9.5% 11.0% 12.7% 12.5% 11.7% 14.9% FE 22.0% 12.9% 10.2% 11.8% 13.9% 13.8% 12.5% 16.6%

Table E 16. 1 hour Statistics for Corpus Christi ( CAMS 4 & 21), September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA 13.0%  11.9%  0.9% 2.7%  1.5% 6.9% 9.6%  0.7% APPA  31.8%  24.7% 24.9%  18.6%  15.2%  3.1% 4.9%  15.0% PTB  1  2 0  6  4  2 3 2 NB  29.4%  23.6%  21.5%  23.0%  21.7%  14.3%  8.3%  25.4% FB  35.5%  27.2%  24.2%  26.1%  24.7%  16.7%  10.5%  31.4% NE 29.4% 23.6% 21.5% 23.0% 21.7% 15.6% 16.2% 25.4% FE 35.5% 27.2% 24.2% 26.1% 24.7% 18.0% 17.9% 31.4% E 23 Table E 17. 1 hour Statistics for CAMS 87, September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA  13.8% 1.9% 8.4% 6.2% 3.0% 0.7%  0.5%  16.8% APPA  44.8% 18.5%  17.3%  3.5%  6.6% 15.1%  3.9%  20.4% PTB 0  6  1  2  1 1  3 1 NB  31.5%  13.3%  7.6%  3.7%  9.7%  21.5%  18.7%  20.0% FB  37.8%  14.4%  8.2%  4.0%  10.8%  24.6%  24.4%  23.3% NE 31.5% 13.3% 11.2% 5.3% 10.4% 21.5% 20.0% 20.0% FE 37.8% 14.4% 11.9% 5.5% 11.5% 24.6% 25.6% 23.3%

Figure E 4. 1 hour Unpaired Peak Accuracy, CAMS 23, September 13   20, 1999.

Unpaired Peak Accuracy for AACOG Modeled Values at CAMS 23, Sept. 13 20, 1999  30%  20%  10% 0% 10% 20% 30%

9/ 13/ 1999 9/ 14/ 1999 9/ 15/ 1999 9/ 16/ 1999 9/ 17/ 1999 9/ 18/ 1999 9/ 19/ 1999 9/ 20/ 1999 Date Percent Difference Run 18. sos. e EPA Guidance + 20%

EPA Guidance  20% E 24 Figure E 5. 1 hour Unpaired Peak Accuracy, CAMS 58, September 13   20, 1999.

Figure E 6. 1 hour Unpaired Peak Accuracy, Central Texas Monitors ( CAMS 3, 23, 38, 58, 59, 62, 601, 678), September 13   20, 1999.

Unpaired Peak Accuracy for AACOG Modeled Values in the Central Texas Region, Sept. 13 20, 1999  30%  20%  10% 0% 10% 20% 30%

9/ 13/ 1999 9/ 14/ 1999 9/ 15/ 1999 9/ 16/ 1999 9/ 17/ 1999 9/ 18/ 1999 9/ 19/ 1999 9/ 20/ 1999 Date Percent Difference Run 18. sos. e EPA Guidance + 20%

EPA Guidance  20% Unpaired Peak Accuracy for AACOG Modeled Values at CAMS 58, Sept. 13 20, 1999  30%  20%  10% 0% 10% 20% 30%

9/ 13/ 1999 9/ 14/ 1999 9/ 15/ 1999 9/ 16/ 1999 9/ 17/ 1999 9/ 18/ 1999 9/ 19/ 1999 9/ 20/ 1999 Date Percent Difference Run 18. sos. e EPA Guidance + 20%

EPA Guidance  20% E 25 Figure E 7. 1 hour Average Paired Peak Accuracy at CAMS 23, September 13 20, 1999.

Figure E 8. 1 hour Average Paired Peak Accuracy at CAMS 58, September 13 20, 1999. Average Paired Peak Accuracy for AACOG Modeled Values at CAMS 23, Sept. 13 20, 1999  40%  30%  20%  10% 0% 10% 20% 30% 40%

9/ 13/ 1999 9/ 14/ 1999 9/ 15/ 1999 9/ 16/ 1999 9/ 17/ 1999 9/ 18/ 1999 9/ 19/ 1999 9/ 20/ 1999 Date Percent Difference Run 18. sos. e Average Paired Peak Accuracy for AACOG Modeled Values at CAMS 58, Sept. 13 20, 1999  40%  30%  20%  10% 0% 10% 20% 30% 40%

9/ 13/ 1999 9/ 14/ 1999 9/ 15/ 1999 9/ 16/ 1999 9/ 17/ 1999 9/ 18/ 1999 9/ 19/ 1999 9/ 20/ 1999 Date Percent Difference Run 18. sos. e E 26 Figure E 9. 1 hour Average Paired Peak Accuracy at Central Texas Monitors ( CAMS 3, 23, 38, 58, 59, 62, 601, 678), September 13 20, 1999.

Figure E 10. 1 hour Normalized Bias at CAMS 23, September 13   20, 1999. Average Paired Peak Accuracy for AACOG Modeled Values in the Central Texas Region, Sept. 13 20, 1999  40%  30%  20%  10% 0% 10% 20% 30% 40%

9/ 13/ 1999 9/ 14/ 1999 9/ 15/ 1999 9/ 16/ 1999 9/ 17/ 1999 9/ 18/ 1999 9/ 19/ 1999 9/ 20/ 1999 Date Percent Difference Run 18. sos. e Normalized Bias for AACOG Modeled Values at CAMS 23, Sept. 13 20, 1999  35%  25%  15%  5% 5% 15% 25% 35%

9/ 13/ 1999 9/ 14/ 1999 9/ 15/ 1999 9/ 16/ 1999 9/ 17/ 1999 9/ 18/ 1999 9/ 19/ 1999 9/ 20/ 1999 Date Percent Difference Run 18. sos. e EPA Guidance + 15% EPA Guidance  15% E 27 Figure E 11. 1 hour Normalized Bias at CAMS 58, September 13   20, 1999.

Figure E 12. 1 hour Normalized Bias at Central Texas Monitors ( CAMS 3, 23, 38, 58, 59, 62, 601, 678), September 13   20, 1999.

Normalized Bias for AACOG Modeled Values in the Central Texas Region, Sept. 13 20, 1999  35%  25%  15%  5% 5% 15% 25% 35%

9/ 13/ 1999 9/ 14/ 1999 9/ 15/ 1999 9/ 16/ 1999 9/ 17/ 1999 9/ 18/ 1999 9/ 19/ 1999 9/ 20/ 1999 Date Percent Difference Run 18. sos. e EPA Guidance + 15% EPA Guidance  15% Normalized Bias for AACOG Modeled Values at CAMS 58, Sept. 13 20, 1999  35%  25%  15%  5% 5% 15% 25% 35%

9/ 13/ 1999 9/ 14/ 1999 9/ 15/ 1999 9/ 16/ 1999 9/ 17/ 1999 9/ 18/ 1999 9/ 19/ 1999 9/ 20/ 1999 Date Percent Difference Run 18. sos. e EPA Guidance + 15% EPA Guidance  15% E 28 Figure E 13. 1 hour Normalized Error at CAMS 23, September 13   20, 1999.

Figure E 14. 1 hour Normalized Error at CAMS 58, September 13   20, 1999. Normalized Error for AACOG Modeled Values at CAMS 23, Sept. 13 20, 1999 0% 5% 10% 15% 20% 25% 30% 35% 40%

9/ 13/ 1999 9/ 14/ 1999 9/ 15/ 1999 9/ 16/ 1999 9/ 17/ 1999 9/ 18/ 1999 9/ 19/ 1999 9/ 20/ 1999 Date Percent Difference Run 18. sos. e EPA Guidance + 35%

Normalized Error for AACOG Modeled Values at CAMS 58, Sept. 13 20, 1999 0% 5% 10% 15% 20% 25% 30% 35% 40%

9/ 13/ 1999 9/ 14/ 1999 9/ 15/ 1999 9/ 16/ 1999 9/ 17/ 1999 9/ 18/ 1999 9/ 19/ 1999 9/ 20/ 1999 Date Percent Difference Run 18. sos. e EPA Guidance + 35% E 29 Figure E 15. 1 hour Normalized Error at Central Texas Monitors ( CAMS 3, 23, 38, 58, 59, 62, 601, 678), September 13   20, 1999.

Figure E 16. 1 hour Timing Bias at CAMS 23, September 13   20, 1999. Normalized Error for AACOG Modeled Values in the Central Texas Region, Sept. 13 20, 1999 0% 5% 10% 15% 20% 25% 30% 35% 40%

9/ 13/ 1999 9/ 14/ 1999 9/ 15/ 1999 9/ 16/ 1999 9/ 17/ 1999 9/ 18/ 1999 9/ 19/ 1999 9/ 20/ 1999 Date Percent Difference Run 18. sos. e EPA Guidance + 35%

Bias in time for AACOG Modeled Values at CAMS 23, Sept. 13 20, 1999  6  5  4  3  2  1 0 1 2 3 4 5 9/ 13/ 1999 9/ 14/ 1999 9/ 15/ 1999 9/ 16/ 1999 9/ 17/ 1999 9/ 18/ 1999 9/ 19/ 1999 9/ 20/ 1999 Date Difference in Time ( Hours)

Run 18. sos. e E 30 Figure E 17. 1 hour Timing Bias at CAMS 58, September 13   20, 1999.

Figure E 18. 1 hour Timing Bias at Central Texas Monitors 23 ( CAMS 3, 23, 38, 58, 59, 62, 601, 678), September 13   20, 1999. Bias in time for AACOG Modeled Values at CAMS 58, Sept. 13 20, 1999  6  5  4  3  2  1 0 1 2 3 4 5 9/ 13/ 1999 9/ 14/ 1999 9/ 15/ 1999 9/ 16/ 1999 9/ 17/ 1999 9/ 18/ 1999 9/ 19/ 1999 9/ 20/ 1999 Date Difference in Time ( Hours)

Run 18. sos. e Bias in time for AACOG Modeled Values in the Central Texas Region, Sept. 13 20, 1999  6  5  4  3  2  1 0 1 2 3 4 5 9/ 13/ 1999 9/ 14/ 1999 9/ 15/ 1999 9/ 16/ 1999 9/ 17/ 1999 9/ 18/ 1999 9/ 19/ 1999 9/ 20/ 1999 Date Difference in Time ( Hours)

Run 18. sos. e E 31 Figure E 19. 1 hour Fractional Bias at CAMS 23, September 13   20, 1999.

Figure E 20. 1 hour Fractional Bias at CAMS 58, September 13   20, 1999. Fractional Bias for AACOG Modeled Values at CAMS 23, Sept. 13 20, 1999  35%  25%  15%  5% 5% 15% 25% 35%

9/ 13/ 1999 9/ 14/ 1999 9/ 15/ 1999 9/ 16/ 1999 9/ 17/ 1999 9/ 18/ 1999 9/ 19/ 1999 9/ 20/ 1999 Date Percent Difference Run 18. sos. e EPA Guidance + 20% EPA Guidance  20%

Fractional Bias for AACOG Modeled Values at CAMS 58, Sept. 13 20, 1999  35%  25%  15%  5% 5% 15% 25% 35%

9/ 13/ 1999 9/ 14/ 1999 9/ 15/ 1999 9/ 16/ 1999 9/ 17/ 1999 9/ 18/ 1999 9/ 19/ 1999 9/ 20/ 1999 Date Percent Difference Run 18. sos. e EPA Guidance + 20% EPA Guidance  20% E 32 Figure E 21. 1 hour Fractional Bias at Central Texas Monitors 23 ( CAMS 3, 23, 38, 58, 59, 62, 601, 678), September 13   20, 1999.

Time Series Plots In addition to conducting 1 hour statistical measurements, staff produced time series plots of observed versus predicted 1 hour ozone concentrations. These plots provide an indication of the model's ability to replicate peak predictions, the presence of bias within the diurnal cycles, as well as biases in timing of the predicted daily maxima. Time series plots for the four San Antonio area monitors are provided in figures E 22 through E 25. These graphs indicate that diurnal trends were replicated quite well, although peak concentrations were slightly under predicted at CAMS 23, 58, and 678 during several episode days. Peak concentrations at CAMS 59 were consistently under predicted, except for the final day of the episode, September 20th. Fractional Bias for AACOG Modeled Values in the Central Texas Region, Sept. 13 20, 1999  35%  25%  15%  5% 5% 15% 25% 35%

9/ 13/ 1999 9/ 14/ 1999 9/ 15/ 1999 9/ 16/ 1999 9/ 17/ 1999 9/ 18/ 1999 9/ 19/ 1999 9/ 20/ 1999 Date Percent Difference Run 18. sos. e EPA Guidance + 20% EPA Guidance  20% E 33 Figure E 22. Observed versus Predicted 1 hour Average Ozone Concentrations at CAMS 23, September 13   20, 1999.

Figure E 23. Observed versus Predicted 1 hour Average Ozone Concentrations at CAMS 58, September 13   20, 1999. 0 20 40 60 80 100 120 9/ 13/ 1999 9/ 14/ 1999 9/ 15/ 1999 9/ 16/ 1999 9/ 17/ 1999 9/ 18/ 1999 9/ 19/ 1999 9/ 20/ 1999 Date O z o n e ( p p b ) Min/ Max Run. 18. sos. e Predicted Observed 0 20 40 60 80 100 120 9/ 13/ 1999 9/ 14/ 1999 9/ 15/ 1999 9/ 16/ 1999 9/ 17/ 1999 9/ 18/ 1999 9/ 19/ 1999 9/ 20/ 1999 Date O z o n e ( p p b ) Min/ Max Observed Run. 18. sos. e Predicted E 34 Figure E 24. Observed versus Predicted 1 hour Average Ozone Concentrations at CAMS 59, September 13   20, 1999.

0 20 40 60 80 100 120 9/ 13/ 1999 9/ 14/ 1999 9/ 15/ 1999 9/ 16/ 1999 9/ 17/ 1999 9/ 18/ 1999 9/ 19/ 1999 9/ 20/ 1999 Date O z o n e ( p p b ) Min/ Max Observed Run. 18. sos. e Predicted Figure E 25. Observed versus Predicted 1 hour Average Ozone Concentrations at CAMS 678, September 13   20, 1999.

0 20 40 60 80 100 120 9/ 13/ 1999 9/ 14/ 1999 9/ 15/ 1999 9/ 16/ 1999 9/ 17/ 1999 9/ 18/ 1999 9/ 19/ 1999 9/ 20/ 1999 Date O z o n e ( p p b ) Min/ Max Observed Run. 18. sos. e Predicted E 35 Scatter Plots Scatter plots of 1 hour observed ( x) and predicted ( y) data for the four SAER monitors are provided in figures E 26 through E 29. The observed/ predicted data points for each monitor follows the 1: 1 reference line fairly well and each plot exhibits moderate, positive correlation coefficients. Some outlier data pairs are evident in each chart, however.

Figure E 26. Scatter Plot of 1 hour Observed/ Predicted Data Pairs at CAMS 23.

y = 0.6508x + 19.189 R 2 = 0.7325 0 20 40 60 80 100 120 0 20 40 60 80 100 120 O3 Observed ( ppb) O 3 P r e d i c t e d ( p p b )

Figure E 27. Scatter Plot of 1 hour Observed/ Predicted Data Pairs at CAMS 58.

y = 0.5182x + 32.088 R 2 = 0.6597 0 20 40 60 80 100 120 0 20 40 60 80 100 120 O3 Observed ( ppb) O 3 P r e d i c t e d ( p p b ) E 36 Figure E 28. Scatter Plot of 1 hour Observed/ Predicted Data Pairs at CAMS 59.

y = 0.5277x + 23.99 R 2 = 0.6597 0 20 40 60 80 100 120 0 20 40 60 80 100 120 O3 Observed ( ppb) O 3 P r e d i c t e d ( p p b )

Figure E 29. Scatter Plot of 1 hour Observed/ Predicted Data Pairs at CAMS 678.

y = 0.5152x + 30.363 R 2 = 0.6785 0 20 40 60 80 100 120 0 20 40 60 80 100 120 O3 Observed ( ppb) O 3 P r e d i c t e d ( p p b ) E 37 Weekend/ Weekday Comparisons Weekend/ weekday analyses may be useful for determining whether the model responds appropriately to changes in precursor emission rates. Typically, EIs for weekdays are very different than weekends. For example, vehicle miles traveled ( VMT) are generally lower on weekends than weekdays. In areas such as San Antonio where mobile sources are the primary source of NOx emissions, this means the NOx EIs for Saturday and Sunday are the lowest of the week.

Figure E 30 provides a comparison between predicted/ observed 1 hour average ozone concentrations at CAMS 23 and the daily NOx EI for Bexar County. As shown, observed and predicted concentrations track fairly closely throughout the episode. Both curves show a rise in ozone concentrations on Saturday as the result of lower NOx emissions ( NOx reduction disbenefit). Higher ozone concentrations were predicted at CAMS 58 ( figure E 31) on Saturday and Sunday, although actual 1 hour measurements fell on Sunday.

Figure E 32 aggregates the predicted peak concentrations ( September 13   20, 1999) of the four San Antonio area monitors into a single chart and compares the data to the daily NOx EI for Bexar County. Unlike the predictions at CAMS 23 and 58, the peak predictions at CAMS 59 and 678 do not rise as sharply between Friday, September 17th and Saturday, September 18th. These results are consistent with expectations since CAMS 59 and 678 are upwind monitors.

Figure E 30. Comparison of Observed/ predicted 1 hour Concentrations at CAMS 23 and Daily NOx EI for Bexar County, September 13   20, 1999.

0 50 100 150 200 250 300 Mon 13 Sep Tue 14 Sep Wed 15 Sep Thu 16 Sep Fri 17 Sep Sat 18 Sep Sun 19 Sep Mon 20 Sep Total NOx ( tons/ day)

0 25 50 75 100 125 Ozone ( ppb) Total NOx Observed CAMS 23 Predicted CAMS 23 E 38 Figure E 31. Comparison of Observed/ predicted 1 hour Concentrations at CAMS 58 and Daily NOx EI for Bexar County, September 13   20, 1999.

Figure E 32. Comparison of Observed/ predicted 1 hour Concentrations at Four San Antonio CAMS and Daily NOx EI for Bexar County, September 13   20, 1999. 0 50 100 150 200 250 300 Mon 13 Sep Tue 14 Sep Wed 15 Sep Thu 16 Sep Fri 17 Sep Sat 18 Sep Sun 19 Sep Mon 20 Sep Total NOx ( tons/ day)

0 25 50 75 100 125 Ozone ( ppb) Total NOx Observed CAMS 58 Predicted CAMS 58 0 50 100 150 200 250 300 Mon 13 Sep Tue 14 Sep Wed 15 Sep Thu 16 Sep Fri 17 Sep Sat 18 Sep Sun 19 Sep Mon 20 Sep Total NOx ( tons/ day)

0 25 50 75 100 125 Ozone ( ppb) Total NOx CAMS 58 CAMS 23 CAMS 678 CAMS 59 Adjusted VMT E 39 Model Performance: 8 Hour Average Ozone Concentrations In their draft 8 hour guidance, the U. S. EPA recommends conducting a variety of tests to evaluate a photochemical model. In broad terms, these evaluations include performance tests and diagnostic analyses. Both types of evaluations were conducted on the September 1999 simulation with excellent results. The performance tests, used to determine how well the model predicted 8 hour concentrations are described in the following sections on ozone metrics, graphic analyses, and tile plots Ozone Metrics Metrics are used to evaluate how closely predicted ozone concentrations match observations, both in terms of spatial and temporal distributions. To evaluate the performance of the 1999 base case, staff conducted statistical tests from EPA's 1 hour and 8 hour guidance documents. To apply the 1 hour metrics to 8 hour data, staff utilized ENVIRON's " camxpost" program, described in the 1 hour statistics section. The program provided unpaired peak accuracy ( UPA), average paired peak accuracy ( APPA), peak timing bias ( PTB), normalized bias ( NB), fractional bias, normalized error ( NE), and fractional error ( FE) for peak 8 hour data. Results of these 8 hour tests are provided in tables E 18 through E 34. Whenever daily modeled predictions were less than 60 ppb, statistical tests were not performed. These days are indicated by " N/ A" in the appropriate columns.

Yellow highlighted values in these tables represent statistics that fall outside EPA's performance criteria on primary episode days ( September 15   20, 1999. Although it is not necessary to conduct these tests on model initialization days ( September 13 14, 1999), statistics for the initialization period are included for comparison purposes. Model initialization statistics that fall outside performance thresholds are listed in bold type. Columns where data are missing represent days in which predicted measurements were less than 60 ppb.

EPA recommends grouping monitored data in terms of location, i. e., downwind, upwind, and city center, as a means of developing useful comparisons. Averaged metrics tests were conducted for groups of monitors when possible. 2 The Central Texas monitoring network is relatively sparse; consequently, the Austin and San Antonio areas, in conjunction with the TCEQ and the U. S. EPA Region 6, recommended evaluating performance based on averaged data from all Central Texas stations. As a result, metrics tests were applied to averaged results at all eight Central Texas monitors, as well as groups of monitors. Monitor numbers, locations, and monitor groups are as follows:

2 Austin has two monitors, both of which are downwind. San Antonio has two downwind, two upwind, and no city center monitors. As a consequence, there are no average statistics for city center for Austin, San Antonio or Central Texas. E 40 CAMS # Monitor Name/ Group Name Location AIRS # 3 Murchison Travis County 48 453 0014 4 Corpus Christi West Nueces County 48 355 0025 21 Corpus Christi Tuloso Nueces County 48 355 0026 23 San Antonio Northwest Bexar County 48 029 0032 38 Audubon Travis County 48 453 0020 58 Camp Bullis Bexar County 48 029 0052 59 Calaveras Lake Bexar County 48 029 0059 62 San Marcos Caldwell County 48 055 0062 87 Victoria Victoria County 48 469 0003 601 Fayette Fayette County 48 149 0001 678 CPS Pecan Valley Bexar County 48 029 0055 3, 38 Austin Downwind Monitors Travis County 23, 58 San Antonio Downwind Monitors Bexar County 59, 678 San Antonio Upwind Monitors Bexar County 23, 58, 59, 678 San Antonio Monitors Bexar County 3, 23, 38,58 Central Texas Downwind Mntrs Bexar, Travis 59, 62, 601, 678 Central Texas Upwind Mntrs Bexar, Caldwell, Fayette 3, 23, 38, 58, 59, 62, 601, 678 Central Texas Monitors Bexar, Caldwell, Fayette, Travis Applying the same performance criteria recommended for 1 hour statistics to peak 8 hour observed/ predicted data comparisons, the results are excellent. Although a few individual monitors exhibit results that fall outside EPA thresholds ( such as the negative bias exhibited by the coastal monitors), outcomes for monitor groups generally fell within acceptable ranges. The sole exception was unpaired peak accuracy on September 18th when testing paired data for San Antonio upwind monitors and Central Texas upwind monitors.

Table E 18. 8 hour Statistics for CAMS 3, September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA N/ A N/ A 18.9% 13.0%  0.9%  1.3%  0.9% 8.8% APPA N/ A N/ A 1.2%  6.7%  14.3%  8.7%  4.4%  19.0% PTB N/ A N/ A 0 1 0 1 0 0 NB N/ A N/ A 3.1%  4.8%  12.9%  10.9%  3.3%  18.2% FB N/ A N/ A 3.0%  5.0%  13.8%  12.1%  3.5%  20.2% NE N/ A N/ A 3.1% 5.6% 12.9% 11.4% 5.6% 18.2% FE N/ A N/ A 3.0% 5.8% 13.8% 12.6% 5.7% 20.2%

Table E 19. 8 hour Statistics for CAMS 38, September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA N/ A 9.9% 3.3%  8.4%  11.5%  13.0%  11.1% 26.7% APPA N/ A  7.1%  9.5%  12.7%  13.7%  19.0%  18.3%  16.3% PTB N/ A 0 1 0 0 1 1  1 NB N/ A  6.8%  6.0%  10.4%  15.4%  17.0%  10.7%  17.3% FB N/ A  7.1%  6.2%  11.0%  16.9%  19.0%  11.7%  19.1% NE N/ A 6.8% 6.0% 10.4% 15.4% 17.0% 10.9% 17.3% FE N/ A 7.1% 6.3% 11.0% 16.9% 19.0% 11.9% 19.1% E 41 Table E 20. 8 hour Statistics for Austin Downwind Monitors ( CAMS 3 & 38), September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA N/ A 9.9% 3.3%  8.4%  11.5%  13.0%  11.1% 8.8% APPA N/ A  7.1%  4.1%  9.7%  14.0%  13.8%  11.4%  17.6% PTB N/ A 0 1 1 0 1 1  1 NB N/ A  6.8%  3.7%  8.7%  14.4%  14.8%  7.8%  17.7% FB N/ A  7.1%  3.9%  9.2%  15.7%  16.5%  8.5%  19.6% NE N/ A 6.8% 5.3% 9.0% 14.4% 15.0% 8.9% 17.7% FE N/ A 7.1% 5.5% 9.4% 15.7% 16.7% 9.5% 19.6%

Table E 21. 8 hour Statistics for CAMS 23, September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA N/ A 3.5% 1.1%  1.2% 13.6% 6.3% 13.4% 10.5% APPA N/ A  14.7%  12.9%  20.8% 0.0%  0.3%  5.0% 4.0% PTB N/ A  1 0 0 1 0 0 0 NB N/ A  14.0%  9.3%  16.6%  7.9%  1.4%  2.0% 8.0% FB N/ A  15.1%  9.9%  18.3%  8.3%  1.5%  2.0% 7.6% NE N/ A 14.0% 9.3% 16.6% 7.9% 3.6% 3.6% 8.0% FE N/ A 15.1% 9.9% 18.3% 8.3% 3.6% 3.7% 7.6%

Table E 22. 8 hour Statistics for CAMS 58, September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA N/ A 9.0% 5.0% 8.1% 16.0% 2.0% 11.8% 14.2% APPA N/ A  6.3%  11.1%  5.9% 0.7%  11.1% 7.9%  0.8% PTB N/ A 0 0 0 1 0 0  1 NB N/ A  5.3%  6.7%  3.1% 3.1%  7.8% 11.2% 1.2% FB N/ A  5.5%  7.0%  3.2% 3.0%  8.2% 10.4% 1.2% NE N/ A 5.3% 7.1% 4.3% 3.2% 7.8% 11.2% 2.9% FE N/ A 5.5% 7.4% 4.4% 3.2% 8.2% 10.4% 2.8%

Table E 23. 8 hour Statistics for CAMS 59, September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA  9.6% 1.9% 2.0%  6.1% 1.1% 21.6% 14.2% 10.8% APPA  20.2%  18.6%  21.2%  13.3%  12.9%  19.7%  15.5%  7.2% PTB 0 1 2 4 1 1 0 1 NB  19.6%  17.2%  16.8%  9.6%  6.8%  17.0%  9.6%  11.2% FB  21.8%  18.9%  18.5%  10.3%  7.5%  18.7%  10.2%  12.1% NE 19.6% 17.2% 16.8% 10.2% 10.1% 17.0% 9.6% 11.2% FE 21.8% 18.9% 18.5% 11.0% 10.7% 18.7% 10.2% 12.1% E 42 Table E 24. 8 hour Statistics for CAMS 678, September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA N/ A N/ A 12.6% 9.8% 31.1% 29.5% 20.1% 7.6% APPA N/ A N/ A  10.1%  7.5% 2.6%  5.9%  4.8%  1.7% PTB N/ A N/ A 1 0  1 0 0 1 NB N/ A N/ A  6.3%  5.2% 3.7%  4.0%  0.4% 0.1% FB N/ A N/ A  6.5%  5.3% 3.6%  4.1%  0.6%  0.2% NE N/ A N/ A 6.3% 5.2% 3.7% 4.1% 5.6% 6.7% FE N/ A N/ A 6.5% 5.3% 3.6% 4.2% 5.6% 6.6%

Table E 25. 8 hour Statistics for San Antonio Downwind Monitors ( CAMS 23 & 58), September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA N/ A 3.5% 1.1%  1.2% 13.6% 2.0% 11.8% 10.5% APPA N/ A 10.5%  12.0%  13.3%  4.1%  5.7% 1.5% 1.6% PTB N/ A  1 0 0 1 0 0  1 NB N/ A  10.1%  7.7%  10.3%  2.4%  4.4% 4.6% 4.2% FB N/ A  10.8%  8.1%  11.2%  2.6%  4.7% 4.2% 4.2% NE N/ A 10.1% 8.0% 10.9% 5.6% 5.6% 7.4% 5.1% FE N/ A 10.8% 8.4% 11.8% 5.7% 5.8% 7.1% 4.9%

Table E 26. 8 hour Statistics for San Antonio Upwind Monitors ( CAMS 59 & 678), September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA  9.6% 1.9% 2.0%  6.1% 1.1% 21.6% 14.2% 7.6% APPA  20.2%  18.6%  15.6%  10.4%  5.2%  12.8%  10.2%  4.4% PTB 0 1 2 2 0 1 0 1 NB  19.6%  17.2%  13.5%  8.5%  3.8%  12.4%  6.1%  6.2% FB  21.8%  18.9%  14.7%  9.1%  4.3%  13.6%  6.5%  6.8% NE 19.6% 17.2% 13.5% 9.0% 8.3% 12.5% 8.1% 9.2% FE 21.8% 18.9% 14.7% 9.6% 8.7% 13.6% 8.4% 9.7%

Table E 27. 8 hour Statistics for all San Antonio Monitors ( CAMS 23, 58, 59 & 678) September 13   20, 1999. San Antonio Monitors Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA  9.6% 3.5% 1.1%  1.2% 1.1% 2.0% 11.8% 7.6% APPA  20.2%  13.2%  13.8%  11.9%  4.7%  9.3%  4.3%  1.4% PTB 0 0 1 1 1 0 0 0 NB  19.6%  12.7%  10.9%  9.3%  3.1%  8.5%  0.9%  1.3% FB  21.8%  13.7%  11.8%  10.0%  3.5%  9.2%  1.3%  1.8% NE 19.6% 12.7% 11.0% 9.8% 6.9% 9.1% 7.7% 7.3% FE 21.8% 13.7% 11.9% 10.5% 7.2% 9.8% 7.8% 7.4% E 43 Table E 28. 8 hour Statistics for CAMS 601, September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA N/ A N/ A 6.3% 28.9%  0.6% 3.2% 11.5% 17.0% APPA N/ A N/ A  2.2% 1.2%  14.4%  5.8%  3.0% 1.7% PTB N/ A N/ A  1 1  1 1  3 0 NB N/ A N/ A  3.5% 1.2%  15.4%  12.2%  11.1%  3.2% FB N/ A N/ A  3.6% 1.2%  16.9%  13.2%  12.2%  3.3% NE N/ A N/ A 3.5% 1.4% 15.4% 12.2% 11.5% 3.6% FE N/ A N/ A 3.6% 1.4% 16.9% 13.2% 12.7% 3.7%

Table E 29. 8 hour Statistics for CAMS 62, September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA N/ A N/ A 15.1% 13.1% 2.9% 13.0% 10.1% 24.5% APPA N/ A N/ A  6.1% 6.8%  13.3%  11.0%  6.7% 3.3% PTB N/ A N/ A  1 1 6 1 0 0 NB N/ A N/ A  2.1% 6.9%  7.7%  8.3%  2.8% 4.2% FB N/ A N/ A  2.1% 6.6%  8.6%  8.7%  3.0% 4.1% NE N/ A N/ A 3.3% 6.9% 11.8% 8.3% 5.8% 4.2% FE N/ A N/ A 3.3% 6.6% 12.5% 8.7% 5.9% 4.1%

Table E 30. 8 hour Statistics for Central Texas Downwind Monitors ( CAMS 3, 23, 38, 58) September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA N/ A 3.5% 1.1%  8.4%  11.5%  13.0%  11.1% 8.8% APPA N/ A  9.4%  8.1%  11.5%  9.1%  9.8%  5.0%  8.0% PTB N/ A 0 0 0 1 1 0  1 NB N/ A  9.3%  5.4%  9.5%  10.1%  10.9%  3.0%  8.5% FB N/ A  10.8%  8.1%  11.2%  2.6%  4.7% 4.2% 4.0% NE N/ A 9.3% 6.4% 9.9% 11.2% 11.4% 8.3% 12.4% FE N/ A 9.9% 6.7% 10.5% 12.1% 12.6% 8.6% 13.4%

Table E 31. 8 hour Statistics for Central Texas Upwind Monitors ( CAMS 59, 62, 601, 678) September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA  9.6% 1.9% 2.0%  6.1%  0.6% 21.6% 14.2% 7.6% APPA  20.2%  18.6%  9.6%  3.0%  8.4%  10.1%  7.1% 3.2% PTB 0 1 0 2 1 1  1 1 NB  19.6%  17.2%  8.5%  3.9%  8.5%  11.0%  6.9%  3.1% FB  21.8%  18.9%  9.2%  4.3%  9.4%  11.9%  7.6%  3.4% NE 19.6% 17.2% 8.8% 6.9% 12.2% 11.0% 8.9% 6.5% FE 21.8% 18.9% 9.5% 7.3% 13.0% 11.9% 9.3% 6.7% E 44 Table E 32. 8 hour Statistics for Central Texas ( CAMS 3, 23, 38, 58, 59, 62, 601, 678), September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA  9.6% 3.5% 1.1%  8.4%  11.5%  13.0%  11.1% 8.8% APPA  20.2%  11.7%  9.0%  7.3%  9.3%  10.2%  6.2%  4.5% PTB 0 0 0 1 1 1 0 0 NB  19.6%  11.6%  7.1%  6.7%  9.5%  11.0%  4.9% 5.9% FB 21.8%  12.5%  7.6%  7.3%  10.4%  12.1%  5.5%  6.7% NE 19.6% 11.6% 7.7% 8.4% 11.5% 11.3% 8.5% 9.5% FE 21.8% 12.5% 8.2% 8.9% 12.3% 12.4% 9.0% 10.1%

Table E 33. 8 hour Statistics for Corpus Christi Monitors ( CAMS 4 & 21), September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA 4.1%  5.5% 0.8%  5.3%  3.6%  1.4% 1.6%  1.2% APPA  25.7%  21.7%  22.2%  22.6%  19.6%  10.1%  6.1%  22.6% PTB 0 1 1 0  2  1 2 2 NB  27.2%  22.4%  19.9%  23.4%  18.8%  14.1%  7.6%  24.2% FB  31.7%  25.5%  22.1%  26.5%  20.9%  15.7%  8.4%  27.8% NE 27.2% 22.4% 19.9% 23.4% 18.8% 14.3% 9.2% 24.2% FE 31.7% 25.5% 22.1% 26.5% 20.9% 15.9% 9.9% 27.8%

Table E 34. 8 hour Statistics for CAMS 87, September 13   20, 1999. Statistic 13 Sep 14 Sep 15 Sep 16 Sep 17 Sep 18 Sep 19 Sep 20 Sep UPA  4.5% 9.8% 13.2% 10.0% 8.2% 0.6% 0.4%  15.9% APPA  31.2%  12.9%  6.4%  3.1%  5.3%  15.2%  4.3%  18.9% PTB 0  1  1 0 1  1 0 1 NB  28.8%  12.8%  6.0%  1.3%  7.9%  18.8%  16.4%  15.6%  33.6%  13.7%  6.3%  1.4%  8.3%  20.8%  19.4%  17.6% NE 28.8% 12.8% 6.3% 2.7% 7.9% 18.8% 16.4% 17.2% FE 33.6% 13.7% 6.6% 2.8% 8.3% 20.8% 19.4% 19.1%

A variety of analyses are specifically recommended by the EPA in their draft guidance on 8 hour attainment demonstrations ( EPA 1999). These include:   Bias between spatially paired means of observations and predictions of 8 hour daily maximum ozone concentrations, with predicted values based on grid cells ` near' a monitor.   Correlation coefficient and scatter plot for average observed and predicted 8 hour daily maximum ozone concentrations.   Temporal correlation coefficient of observed and nearby predicted 8 hour daily maximum ozone concentrations, which are spatially averaged. If the monitoring network is sufficiently large, concentrations should be grouped into upwind, downwind, and center city locations.   Quantile quantile plots   Fractional bias E 45 The EPA recommended performance goal for each test is:

Test Goal Bias between predicted/ observed mean 8 hour ( and 1 hour) daily maxima near each monitor 20% most monitors ( 8 hr comparisons only)

Fractional bias between predicted/ Observed mean 8 hour ( and 1 hour) daily maxima near each monitor 20% most monitors ( 8 hr comparisons only)

Correlation coefficients, all data, temporally paired means, spatially paired means Moderate to large positive correlation Bias ( 8 hour daily maxima and 1 hour observed/ predicted), all monitors 5   15%

Gross error ( 8 hour daily maxima and 1 hour observed/ predicted), all monitors 30   35%

Staff conducted metric, scatter plot, and quantile quantile ( Q Q) plot analyses using a FORTRAN program developed by ENVIRON International, Inc. Due to some uncertainty as to the most appropriate means of calculating these evaluations, ENVIRON's statistical program performs the calculations using three different methodologies: 1) The predicted daily maximum ozone concentration within grid cells near a monitor; 3 2) The predicted daily maximum ozone concentration within grid cells near a monitor that is closest in magnitude to the observed daily maximum at the monitor; and 3) A bilinear interpolation of predicted daily maximum ozone concentration around the monitor location.

Normalized bias, fractional bias, normalized error, and fractional error calculations for all monitors and monitoring groups in the 4 km subdomain are provided in tables E 35 through E 51. Each table presents the statistical results for all three methodologies.

To compare 8 hour normalized bias statistics more readily, line graphs were created of downwind, upwind, and coastal monitors for each methodology ( figures E 33 through E 35). Episode day is designated by a number ( 1 = 9/ 13/ 99, 2 = 9/ 14/ 99, 3 = 9/ 15/ 99, 4 = 9/ 16/ 99, 5 = 9/ 17/ 99, 6 = 9/ 18/ 99, 7 = 9/ 19/ 99, and 8 = 9/ 20/ 99) in each graph. The model initialization period ( days 1 and 2) are separated by a dashed black line and performance goals are designated by dashed red lines.

Method 1 for calculating normalized bias yields very good results. Discounting the model initialization period, the only days when EPA performance goals were not met using 3 In accordance with EPA guidance, grid cells ` near' a monitor were defined as a 7x7 array of cells ( U. S. EPA, 1999). E 46 method 1were September 15th ( CAMS 59   San Antonio upwind monitor), and September 19th ( CAMS 23 and 58   San Antonio downwind monitors).

Model performance based on the statistical metrics was best when calculated using method 2. The ± 20% performance goal for normalized bias was only exceeded once using this method: September 15th at CAMS 59.

Method 3 yielded the most incidences where performance goals were not met. With the exception of CAMS 23, the normalized bias statistics for each downwind monitor failed performance goals during at least one primary episode day. These include CAMS 38 ( Austin) on September 16th, 18th, and 20th, CAMS 3 ( Austin) on September 20th, and CAMS 58 ( San Antonio) on September 19th. Both Austin monitors ( CAMS 3 & 38) are downwind monitors and both exhibited a negative bias during the modeling episode. Normalized bias calculated using method 3 yielded better results for the upwind monitors. The only days when performance goals were not met were September 15th and 18th, both at CAMS 59 ( San Antonio). In addition, all three coastal monitors failed the normalized bias goal with method 3 on at least one episode day: CAMS 4 ( Corpus Christi) on September 15th and 16th, CAMS 21 ( Corpus Christi) on September 15th, and CAMS 87 ( Victoria) on September 20th.

Line graphs of fractional bias statistics were also developed for each methodology. These graphs are presented in figures E 36 through E 38. Results of the fractional bias calculations are very similar to those for normalized bias, although the incidence of results that failed to meet performance goals increased somewhat with fractional bias. For the daily peak predicted/ observed statistics ( September 15   20, 1999) using Method 1, for example, the performance goal for normalized bias was met on 95% of the days and the performance goal for fractional bias was met on 94% of the days. Using method 2, the ± 20% goal for normalized and fractional bias was met on 98% and 97% of the days, respectively. The poorest performance was associated with evaluating the model using method 3. Even using this strictest methodology, however, the performance goals for normalized and fractional bias were passed on 85% of the primary episode days. E 47 Table E 35. Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for CAMS 3, September 13   20, 1999. Methodology 1: Date MAXOBS1HR MAXPRD1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 53.00 56.21 6.06 5.88 6.06 5.88 9/ 14/ 1999 56.00 70.02 25.04 22.25 25.04 22.25 9/ 15/ 1999 78.00 89.62 14.90 13.86 14.90 13.86 9/ 16/ 1999 73.00 79.73 9.22 8.81 9.22 8.81 9/ 17/ 1999 98.00 102.26 4.35 4.25 4.35 4.25 9/ 18/ 1999 97.00 98.17 1.21 1.20 1.21 1.20 9/ 19/ 1999 101.00 104.52 3.49 3.43 3.49 3.43 9/ 20/ 1999 102.00 103.21 1.19 1.18 1.19 1.18 Methodology 2: Date MAXOBS1HR NEAR1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 53.00 52.95  0.09  0.09 0.09 0.09 9/ 14/ 1999 56.00 55.79  0.38  0.38 0.38 0.38 9/ 15/ 1999 78.00 78.05 0.06 0.06 0.06 0.06 9/ 16/ 1999 73.00 73.03 0.04 0.04 0.04 0.04 9/ 17/ 1999 98.00 97.40  0.61  0.61 0.61 0.61 9/ 18/ 1999 97.00 97.00 0.00 0.00 0.00 0.00 9/ 19/ 1999 101.00 100.89  0.11  0.11 0.11 0.11 9/ 20/ 1999 102.00 103.21 1.19 1.18 1.19 1.18 Methodology 3: Date MAXOBS1HR CAMXPS1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 53.00 51.49  2.85  2.89 2.85 2.89 9/ 14/ 1999 56.00 58.35 4.20 4.11 4.20 4.11 9/ 15/ 1999 78.00 79.62 2.08 2.06 2.08 2.06 9/ 16/ 1999 73.00 68.84  5.70  5.87 5.70 5.87 9/ 17/ 1999 98.00 88.69  9.50  9.97 9.50 9.97 9/ 18/ 1999 97.00 90.65  6.55  6.77 6.55 6.77 9/ 19/ 1999 101.00 98.81  2.17  2.19 2.17 2.19 9/ 20/ 1999 102.00 72.45  28.97  33.88 28.97 33.88 E 48 Table E 36. Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for CAMS 38, September 13   20, 1999. Methodology 1: Date MAXOBS1HR MAXPRD1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 57.00 56.73  0.47  0.47 0.47 0.47 9/ 14/ 1999 66.00 64.87  1.71  1.73 1.71 1.73 9/ 15/ 1999 83.00 86.06 3.69 3.62 3.69 3.62 9/ 16/ 1999 100.00 82.48  17.52  19.20 17.52 19.20 9/ 17/ 1999 109.00 102.26  6.18  6.38 6.18 6.38 9/ 18/ 1999 120.00 98.17  18.19  20.01 18.19 20.01 9/ 19/ 1999 110.00 104.63  4.88  5.00 4.88 5.00 9/ 20/ 1999 83.00 72.89  12.18  12.97 12.18 12.97 Methodology 2: Date MAXOBS1HR NEAR1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 57.00 56.73  0.47  0.47 0.47 0.47 9/ 14/ 1999 66.00 64.87  1.71  1.73 1.71 1.73 9/ 15/ 1999 83.00 83.16 0.19 0.19 0.19 0.19 9/ 16/ 1999 100.00 82.48  17.52  19.20 17.52 19.20 9/ 17/ 1999 109.00 102.26  6.18  6.38 6.18 6.38 9/ 18/ 1999 120.00 98.17  18.19  20.01 18.19 20.01 9/ 19/ 1999 110.00 104.63  4.88  5.00 4.88 5.00 9/ 20/ 1999 83.00 72.89  12.18  12.97 12.18 12.97 Methodology 3: Date MAXOBS1HR CAMXPS1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 57.00 55.57  2.51  2.54 2.51 2.54 9/ 14/ 1999 66.00 59.72  9.52  9.99 9.52 9.99 9/ 15/ 1999 83.00 77.19  7.00  7.25 7.00 7.25 9/ 16/ 1999 100.00 79.95  20.05  22.28 20.05 22.28 9/ 17/ 1999 109.00 95.70  12.20  12.99 12.20 12.99 9/ 18/ 1999 120.00 87.69  26.93  31.11 26.93 31.11 9/ 19/ 1999 110.00 99.42  9.62  10.10 9.62 10.10 9/ 20/ 1999 83.00 64.17  22.69  25.59 22.69 25.59 E 49 Table E 37. Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for Austin monitors   CAMS 3 & 38 ( both are downwind monitors), September 13   20, 1999.

Methodology 1: Date MAXOBS1HR MAXPRD1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 55.00 56.47 2.79 2.70 3.27 3.18 9/ 14/ 1999 61.00 67.45 11.66 10.26 13.37 11.99 9/ 15/ 1999 80.50 87.84 9.29 8.74 9.29 8.74 9/ 16/ 1999 86.50 81.11  4.15  5.19 13.37 14.01 9/ 17/ 1999 103.50 102.26  0.92  1.06 5.27 5.32 9/ 18/ 1999 108.50 98.17  8.49  9.41 9.70 10.61 9/ 19/ 1999 105.50 104.58  0.70  0.79 4.18 4.21 9/ 20/ 1999 92.50 88.05  5.50  5.90 6.68 7.07 Methodology 2: Date MAXOBS1HR NEAR1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 55.00 54.84  0.28  0.28 0.28 0.28 9/ 14/ 1999 61.00 60.33  1.04  1.05 1.04 1.05 9/ 15/ 1999 80.50 80.61 0.13 0.13 0.13 0.13 9/ 16/ 1999 86.50 77.76  8.74  9.58 8.78 9.62 9/ 17/ 1999 103.50 99.83  3.40  3.50 3.40 3.50 9/ 18/ 1999 108.50 97.59  9.10  10.01 9.10 10.01 9/ 19/ 1999 105.50 102.76  2.50  2.56 2.50 2.56 9/ 20/ 1999 92.50 88.05  5.50  5.90 6.68 7.07 Methodology 3: Date MAXOBS1HR CAMXPS1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 55.00 53.53  2.68  2.72 2.68 2.72 9/ 14/ 1999 61.00 59.04  2.66  2.94 6.86 7.05 9/ 15/ 1999 80.50 78.41  2.46  2.60 4.54 4.65 9/ 16/ 1999 86.50 74.40  12.87  14.07 12.87 14.07 9/ 17/ 1999 103.50 92.20  10.85  11.48 10.85 11.48 9/ 18/ 1999 108.50 89.17  16.74  18.94 16.74 18.94 9/ 19/ 1999 105.50 99.12  5.89  6.15 5.89 6.15 9/ 20/ 1999 92.50 68.31  25.83  29.73 25.83 29.73 E 50 Table E 38. Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for CAMS 23, September 13   20, 1999. Methodology 1: Date MAXOBS1HR MAXPRD1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 66.00 56.73  14.05  15.11 14.05 15.11 9/ 14/ 1999 75.00 73.79  1.61  1.63 1.61 1.63 9/ 15/ 1999 92.00 97.21 5.66 5.51 5.66 5.51 9/ 16/ 1999 93.00 88.59  4.74  4.86 4.74 4.86 9/ 17/ 1999 82.00 91.47 11.55 10.92 11.55 10.92 9/ 18/ 1999 102.00 110.88 8.71 8.34 8.71 8.34 9/ 19/ 1999 94.00 118.52 26.09 23.08 26.09 23.08 9/ 20/ 1999 106.00 112.50 6.13 5.95 6.13 5.95 Methodology 2: Date MAXOBS1HR NEAR1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 66.00 56.73  14.05  15.11 14.05 15.11 9/ 14/ 1999 75.00 73.79  1.61  1.63 1.61 1.63 9/ 15/ 1999 92.00 92.01 0.01 0.01 0.01 0.01 9/ 16/ 1999 93.00 88.59  4.74  4.86 4.74 4.86 9/ 17/ 1999 82.00 82.29 0.35 0.35 0.35 0.35 9/ 18/ 1999 102.00 102.16 0.16 0.16 0.16 0.16 9/ 19/ 1999 94.00 94.69 0.73 0.73 0.73 0.73 9/ 20/ 1999 106.00 105.99  0.01  0.01 0.01 0.01 Methodology 3: Date MAXOBS1HR CAMXPS1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 66.00 54.88  16.85  18.40 16.85 18.40 9/ 14/ 1999 75.00 65.41  12.79  13.66 12.79 13.66 9/ 15/ 1999 92.00 82.80  10.00  10.53 10.00 10.53 9/ 16/ 1999 93.00 77.74  16.41  17.88 16.41 17.88 9/ 17/ 1999 82.00 77.80  5.12  5.26 5.12 5.26 9/ 18/ 1999 102.00 105.79 3.72 3.65 3.72 3.65 9/ 19/ 1999 94.00 90.81  3.39  3.45 3.39 3.45 9/ 20/ 1999 106.00 105.71  0.27  0.27 0.27 0.27 E 51 Table E 39. Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for CAMS 58, September 13   20, 1999. Methodology 1: Date MAXOBS1HR MAXPRD1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 61.00 57.07  6.44  6.66 6.44 6.66 9/ 14/ 1999 67.00 70.82 5.70 5.54 5.70 5.54 9/ 15/ 1999 88.00 87.19  0.92  0.92 0.92 0.92 9/ 16/ 1999 83.00 86.38 4.07 3.99 4.07 3.99 9/ 17/ 1999 82.00 91.67 11.79 11.14 11.79 11.14 9/ 18/ 1999 108.00 110.88 2.67 2.63 2.67 2.63 9/ 19/ 1999 96.00 118.52 23.46 21.00 23.46 21.00 9/ 20/ 1999 100.00 106.71 6.71 6.49 6.71 6.49 Methodology 2: Date MAXOBS1HR NEAR1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 61.00 57.07  6.44  6.66 6.44 6.66 9/ 14/ 1999 67.00 67.01 0.01 0.01 0.01 0.01 9/ 15/ 1999 88.00 87.19  0.92  0.92 0.92 0.92 9/ 16/ 1999 83.00 83.06 0.07 0.07 0.07 0.07 9/ 17/ 1999 82.00 81.93  0.09  0.09 0.09 0.09 9/ 18/ 1999 108.00 108.53 0.49 0.49 0.49 0.49 9/ 19/ 1999 96.00 95.72  0.29  0.29 0.29 0.29 9/ 20/ 1999 100.00 99.51  0.49  0.49 0.49 0.49 Methodology 3: Date MAXOBS1HR CAMXPS1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 61.00 53.22  12.75  13.62 12.75 13.62 9/ 14/ 1999 67.00 63.68  4.96  5.08 4.96 5.08 9/ 15/ 1999 88.00 73.64  16.32  17.77 16.32 17.77 9/ 16/ 1999 83.00 80.83  2.61  2.65 2.61 2.65 9/ 17/ 1999 82.00 82.77 0.94 0.93 0.94 0.93 9/ 18/ 1999 108.00 94.55  12.45  13.28 12.45 13.28 9/ 19/ 1999 96.00 115.42 20.23 18.37 20.23 18.37 9/ 20/ 1999 100.00 90.40  9.60  10.08 9.60 10.08 E 52 Table E 40. Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for CAMS 59, September 13   20, 1999. Methodology 1: Date MAXOBS1HR MAXPRD1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 72.00 62.13  13.71  14.72 13.71 14.72 9/ 14/ 1999 67.00 56.70  15.37  16.65 15.37 16.65 9/ 15/ 1999 91.00 70.87  22.12  24.87 22.12 24.87 9/ 16/ 1999 85.00 76.10  10.47  11.05 10.47 11.05 9/ 17/ 1999 82.00 73.04  10.93  11.56 10.93 11.56 9/ 18/ 1999 84.00 77.42  7.83  8.15 7.83 8.15 9/ 19/ 1999 96.00 90.71  5.51  5.67 5.51 5.67 9/ 20/ 1999 97.00 103.84 7.05 6.81 7.05 6.81 Methodology 2: Date MAXOBS1HR NEAR1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 72.00 62.13  13.71  14.72 13.71 14.72 9/ 14/ 1999 67.00 56.70  15.37  16.65 15.37 16.65 9/ 15/ 1999 91.00 70.87  22.12  24.87 22.12 24.87 9/ 16/ 1999 85.00 76.10  10.47  11.05 10.47 11.05 9/ 17/ 1999 82.00 73.04  10.93  11.56 10.93 11.56 9/ 18/ 1999 84.00 77.42  7.83  8.15 7.83 8.15 9/ 19/ 1999 96.00 90.71  5.51  5.67 5.51 5.67 9/ 20/ 1999 97.00 97.01 0.01 0.01 0.01 0.01 Methodology 3: Date MAXOBS1HR CAMXPS1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 72.00 57.06  20.75  23.15 20.75 23.15 9/ 14/ 1999 67.00 52.09  22.25  25.04 22.25 25.04 9/ 15/ 1999 91.00 66.07  27.40  31.74 27.40 31.74 9/ 16/ 1999 85.00 73.35  13.71  14.71 13.71 14.71 9/ 17/ 1999 82.00 67.48  17.71  19.43 17.71 19.43 9/ 18/ 1999 84.00 65.96  21.48  24.06 21.48 24.06 9/ 19/ 1999 96.00 79.28  17.42  19.08 17.42 19.08 9/ 20/ 1999 97.00 99.84 2.93 2.89 2.93 2.89 E 53 Table E 41. Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for CAMS 678, September 13   20, 1999. Methodology 1: Date MAXOBS1HR MAXPRD1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 67.00 63.05  5.90  6.07 5.90 6.07 9/ 14/ 1999 64.00 60.99  4.70  4.82 4.70 4.82 9/ 15/ 1999 79.00 78.00  1.27  1.27 1.27 1.27 9/ 16/ 1999 81.00 76.83  5.15  5.28 5.15 5.28 9/ 17/ 1999 70.00 75.71 8.16 7.84 8.16 7.84 9/ 18/ 1999 84.00 88.35 5.18 5.05 5.18 5.05 9/ 19/ 1999 91.00 96.07 5.57 5.42 5.57 5.42 9/ 20/ 1999 107.00 108.27 1.19 1.18 1.19 1.18 Methodology 2: Date MAXOBS1HR NEAR1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 67.00 63.05  5.90  6.07 5.90 6.07 9/ 14/ 1999 64.00 60.99  4.70  4.82 4.70 4.82 9/ 15/ 1999 79.00 78.00  1.27  1.27 1.27 1.27 9/ 16/ 1999 81.00 76.83  5.15  5.28 5.15 5.28 9/ 17/ 1999 70.00 70.14 0.20 0.20 0.20 0.20 9/ 18/ 1999 84.00 85.89 2.25 2.22 2.25 2.22 9/ 19/ 1999 91.00 91.06 0.07 0.07 0.07 0.07 9/ 20/ 1999 107.00 107.02 0.02 0.02 0.02 0.02 Methodology 3: Date MAXOBS1HR CAMXPS1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 67.00 61.47  8.25  8.61 8.25 8.61 9/ 14/ 1999 64.00 56.38  11.91  12.66 11.91 12.66 9/ 15/ 1999 79.00 69.83  11.61  12.32 11.61 12.32 9/ 16/ 1999 81.00 70.67  12.75  13.62 12.75 13.62 9/ 17/ 1999 70.00 69.50  0.71  0.72 0.71 0.72 9/ 18/ 1999 84.00 77.14  8.17  8.51 8.17 8.51 9/ 19/ 1999 91.00 85.83  5.68  5.85 5.68 5.85 9/ 20/ 1999 107.00 96.44  9.87  10.38 9.87 10.38 E 54 Table E 42. Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for San Antonio downwind monitors ( CAMS 23 & 58), September 13   20, 1999. Methodology 1: Date MAXOBS1HR MAXPRD1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 63.50 56.90  10.24  10.88 10.24 10.88 9/ 14/ 1999 71.00 72.31 2.04 1.96 3.66 3.58 9/ 15/ 1999 90.00 92.20 2.37 2.29 3.29 3.22 9/ 16/ 1999 88.00 87.49  0.33  0.43 4.41 4.42 9/ 17/ 1999 82.00 91.57 11.67 11.03 11.67 11.03 9/ 18/ 1999 105.00 110.88 5.69 5.49 5.69 5.49 9/ 19/ 1999 95.00 118.52 24.77 22.04 24.77 22.04 9/ 20/ 1999 103.00 109.61 6.42 6.22 6.42 6.22 Methodology 2: Date MAXOBS1HR NEAR1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 63.50 56.90  10.24  10.88 10.24 10.88 9/ 14/ 1999 71.00 70.40  0.80  0.81 0.81 0.82 9/ 15/ 1999 90.00 89.60  0.45  0.46 0.47 0.47 9/ 16/ 1999 88.00 85.83  2.33  2.39 2.41 2.46 9/ 17/ 1999 82.00 82.11 0.13 0.13 0.22 0.22 9/ 18/ 1999 105.00 105.35 0.32 0.32 0.32 0.32 9/ 19/ 1999 95.00 95.21 0.22 0.22 0.51 0.51 9/ 20/ 1999 103.00 102.75  0.25  0.25 0.25 0.25 Methodology 3: Date MAXOBS1HR CAMXPS1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 63.50 54.05  14.80  16.01 14.80 16.01 9/ 14/ 1999 71.00 64.55  8.87  9.37 8.87 9.37 9/ 15/ 1999 90.00 78.22  13.16  14.15 13.16 14.15 9/ 16/ 1999 88.00 79.29  9.51  10.26 9.51 10.26 9/ 17/ 1999 82.00 80.29  2.09  2.16 3.03 3.10 9/ 18/ 1999 105.00 100.17  4.37  4.82 8.08 8.46 9/ 19/ 1999 95.00 103.12 8.42 7.46 11.81 10.91 9/ 20/ 1999 103.00 98.06  4.94  5.18 4.94 5.18 E 55 Table E 43. Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for San Antonio upwind monitors ( CAMS 59 & 678), September 13   20, 1999. Methodology 1: Date MAXOBS1HR MAXPRD1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 69.50 62.59  9.80  10.40 9.80 10.40 9/ 14/ 1999 65.50 58.85  10.04  10.73 10.04 10.73 9/ 15/ 1999 85.00 74.44  11.69  13.07 11.69 13.07 9/ 16/ 1999 83.00 76.47  7.81  8.17 7.81 8.17 9/ 17/ 1999 76.00 74.38  1.38  1.86 9.54 9.70 9/ 18/ 1999 84.00 82.89  1.33  1.55 6.51 6.60 9/ 19/ 1999 93.50 93.39 0.03  0.12 5.54 5.54 9/ 20/ 1999 102.00 106.06 4.12 4.00 4.12 4.00 Methodology 2: Date MAXOBS1HR NEAR1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 69.50 62.59  9.80  10.40 9.80 10.40 9/ 14/ 1999 65.50 58.85  10.04  10.73 10.04 10.73 9/ 15/ 1999 85.00 74.44  11.69  13.07 11.69 13.07 9/ 16/ 1999 83.00 76.47  7.81  8.17 7.81 8.17 9/ 17/ 1999 76.00 71.59  5.36  5.68 5.56 5.88 9/ 18/ 1999 84.00 81.66  2.79  2.96 5.04 5.19 9/ 19/ 1999 93.50 90.89  2.72  2.80 2.79 2.87 9/ 20/ 1999 102.00 102.02 0.01 0.01 0.01 0.01 Methodology 3: Date MAXOBS1HR CAMXPS1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 69.50 59.27  14.50  15.88 14.50 15.88 9/ 14/ 1999 65.50 54.24  17.08  18.85 17.08 18.85 9/ 15/ 1999 85.00 67.95  19.50  22.03 19.50 22.03 9/ 16/ 1999 83.00 72.01  13.23  14.17 13.23 14.17 9/ 17/ 1999 76.00 68.49  9.21  10.07 9.21 10.07 9/ 18/ 1999 84.00 71.55  14.82  16.29 14.82 16.29 9/ 19/ 1999 93.50 82.56  11.55  12.46 11.55 12.46 9/ 20/ 1999 102.00 98.14  3.47  3.75 6.40 6.63 E 56 Table E 44. Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for San Antonio monitors ( CAMS 23, 58, 59, 678), September 13   20, 1999. Methodology 1: Date MAXOBS1HR MAXPRD1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 66.50 59.75  10.02  10.64 10.02 10.64 9/ 14/ 1999 68.25 65.58  4.00  4.39 6.85 7.16 9/ 15/ 1999 87.50 83.32  4.66  5.39 7.49 8.14 9/ 16/ 1999 85.50 81.98  4.07  4.30 6.11 6.30 9/ 17/ 1999 79.00 82.97 5.14 4.58 10.61 10.36 9/ 18/ 1999 94.50 96.88 2.18 1.97 6.10 6.04 9/ 19/ 1999 94.25 105.96 12.40 10.96 15.16 13.79 9/ 20/ 1999 102.50 107.83 5.27 5.11 5.27 5.11 Methodology 2: Date MAXOBS1HR NEAR1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 66.50 59.75  10.02  10.64 10.02 10.64 9/ 14/ 1999 68.25 64.62  5.42  5.77 5.43 5.78 9/ 15/ 1999 87.50 82.02  6.07  6.76 6.08 6.77 9/ 16/ 1999 85.50 81.15  5.07  5.28 5.11 5.32 9/ 17/ 1999 79.00 76.85  2.61  2.77 2.89 3.05 9/ 18/ 1999 94.50 93.50  1.23  1.32 2.68 2.76 9/ 19/ 1999 94.25 93.05  1.25  1.29 1.65 1.69 9/ 20/ 1999 102.50 102.38  0.12  0.12 0.13 0.13 Methodology 3: Date MAXOBS1HR CAMXPS1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 66.50 56.66  14.65  15.95 14.65 15.95 9/ 14/ 1999 68.25 59.39  12.98  14.11 12.98 14.11 9/ 15/ 1999 87.50 73.09  16.33  18.09 16.33 18.09 9/ 16/ 1999 85.50 75.65  11.37  12.22 11.37 12.22 9/ 17/ 1999 79.00 74.39  5.65  6.12 6.12 6.58 9/ 18/ 1999 94.50 85.86  9.60  10.55 11.45 12.38 9/ 19/ 1999 94.25 92.84  1.57  2.50 11.68 11.69 9/ 20/ 1999 102.50 98.10  4.20  4.46 5.67 5.91 E 57 Table E 45. Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for CAMS 62, September 13   20, 1999. Methodology 1: Date MAXOBS1HR MAXPRD1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 57.00 60.41 5.98 5.81 5.98 5.81 9/ 14/ 1999 N/ A N/ A N/ A N/ A N/ A N/ A 9/ 15/ 1999 78.00 81.86 4.95 4.83 4.95 4.83 9/ 16/ 1999 70.00 76.98 9.97 9.50 9.97 9.50 9/ 17/ 1999 89.00 91.89 3.25 3.20 3.25 3.20 9/ 18/ 1999 83.00 76.84  7.42  7.71 7.42 7.71 9/ 19/ 1999 86.00 89.41 3.97 3.89 3.97 3.89 9/ 20/ 1999 78.00 82.58 5.87 5.70 5.87 5.70 Methodology 2: Date MAXOBS1HR NEAR1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 57.00 56.97  0.05  0.05 0.05 0.05 9/ 14/ 1999 N/ A N/ A N/ A N/ A N/ A N/ A 9/ 15/ 1999 78.00 78.06 0.08 0.08 0.08 0.08 9/ 16/ 1999 70.00 70.07 0.10 0.10 0.10 0.10 9/ 17/ 1999 89.00 88.86  0.16  0.16 0.16 0.16 9/ 18/ 1999 83.00 76.84  7.42  7.71 7.42 7.71 9/ 19/ 1999 86.00 86.12 0.14 0.14 0.14 0.14 9/ 20/ 1999 78.00 78.12 0.15 0.15 0.15 0.15 Methodology 3: Date MAXOBS1HR CAMXPS1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 57.00 55.72  2.25  2.27 2.25 2.27 9/ 14/ 1999 N/ A N/ A N/ A N/ A N/ A N/ A 9/ 15/ 1999 78.00 70.27  9.91  10.43 9.91 10.43 9/ 16/ 1999 70.00 73.52 5.03 4.91 5.03 4.91 9/ 17/ 1999 89.00 75.97  14.64  15.80 14.64 15.80 9/ 18/ 1999 83.00 72.92  12.14  12.93 12.14 12.93 9/ 19/ 1999 86.00 83.16  3.30  3.36 3.30 3.36 9/ 20/ 1999 78.00 78.12 0.15 0.15 0.15 0.15 E 58 Table E 46. Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for CAMS 601, September 13   20, 1999. Methodology 1: Date MAXOBS1HR MAXPRD1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 64.07 55.73  13.02  13.92 13.02 13.92 9/ 14/ 1999 56.23 58.65 4.30 4.21 4.30 4.21 9/ 15/ 1999 72.90 74.12 1.67 1.66 1.67 1.66 9/ 16/ 1999 70.94 76.39 7.68 7.40 7.68 7.40 9/ 17/ 1999 103.29 94.71  8.31  8.67 8.31 8.67 9/ 18/ 1999 87.12 88.14 1.17 1.16 1.17 1.16 9/ 19/ 1999 85.65 87.36 2.00 1.98 2.00 1.98 9/ 20/ 1999 87.12 97.28 11.66 11.02 11.66 11.02 Methodology 2: Date MAXOBS1HR NEAR1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 64.07 55.73  13.02  13.92 13.02 13.92 9/ 14/ 1999 56.23 56.42 0.34 0.34 0.34 0.34 9/ 15/ 1999 72.90 72.26  0.88  0.88 0.88 0.88 9/ 16/ 1999 70.94 71.30 0.51 0.51 0.51 0.51 9/ 17/ 1999 103.29 94.71  8.31  8.67 8.31 8.67 9/ 18/ 1999 87.12 86.16  1.10  1.11 1.10 1.11 9/ 19/ 1999 85.65 86.12 0.55 0.55 0.55 0.55 9/ 20/ 1999 87.12 87.05  0.08  0.08 0.08 0.08 Methodology 3: Date MAXOBS1HR CAMXPS1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 64.07 52.79  17.61  19.31 17.61 19.31 9/ 14/ 1999 56.23 54.16  3.68  3.75 3.68 3.75 9/ 15/ 1999 72.90 67.46  7.46  7.75 7.46 7.75 9/ 16/ 1999 70.94 72.28 1.89 1.87 1.89 1.87 9/ 17/ 1999 103.29 88.34  14.47  15.60 14.47 15.60 9/ 18/ 1999 87.12 78.53  9.86  10.37 9.86 10.37 9/ 19/ 1999 85.65 80.53  5.98  6.16 5.98 6.16 9/ 20/ 1999 87.12 90.63 4.03 3.95 4.03 3.95 E 59 Table E 47. Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for Central Texas Downwind Monitors ( CAMS 3, 23, 38, 58), September 13   20, 1999. Methodology 1: Date MAXOBS1HR MAXPRD1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 59.25 56.69  3.73  4.09 6.75 7.03 9/ 14/ 1999 66.00 69.88 6.85 6.11 8.52 7.79 9/ 15/ 1999 85.25 90.02 5.83 5.52 6.29 5.98 9/ 16/ 1999 87.25 84.30  2.24  2.81 8.89 9.22 9/ 17/ 1999 92.75 96.92 5.38 4.98 8.47 8.17 9/ 18/ 1999 106.75 104.53  1.40  1.96 7.69 8.05 9/ 19/ 1999 100.25 111.55 12.04 10.62 14.48 13.13 9/ 20/ 1999 97.75 98.83 0.46 0.16 6.55 6.65 Methodology 2: Date MAXOBS1HR NEAR1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 59.25 55.87  5.26  5.58 5.26 5.58 9/ 14/ 1999 66.00 65.37  0.92  0.93 0.93 0.94 9/ 15/ 1999 85.25 85.10  0.16  0.16 0.30 0.30 9/ 16/ 1999 87.25 81.79  5.54  5.99 5.59 6.04 9/ 17/ 1999 92.75 90.97  1.63  1.68 1.81 1.86 9/ 18/ 1999 106.75 101.47  4.39  4.84 4.71 5.16 9/ 19/ 1999 100.25 98.98  1.14  1.17 1.50 1.53 9/ 20/ 1999 97.75 95.40  2.87  3.07 3.47 3.66 Methodology 3: Date MAXOBS1HR CAMXPS1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 59.25 53.79  8.74  9.36 8.74 9.36 9/ 14/ 1999 66.00 61.79  5.77  6.16 7.86 8.21 9/ 15/ 1999 85.25 78.31  7.81  8.37 8.85 9.40 9/ 16/ 1999 87.25 76.84  11.19  12.17 11.19 12.17 9/ 17/ 1999 92.75 86.24  6.47  6.82 6.94 7.29 9/ 18/ 1999 106.75 94.67  10.55  11.88 12.41 13.70 9/ 19/ 1999 100.25 101.12 1.26 0.66 8.85 8.53 9/ 20/ 1999 97.75 83.18  15.38  17.46 15.38 17.46 E 60 Table E 48. Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for Central Texas Upwind Monitors ( CAMS 59, 62, 601, 678), September 13   20, 1999. Methodology 1: Date MAXOBS1HR MAXPRD1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 65.02 60.33  6.66  7.23 9.65 10.13 9/ 14/ 1999 62.41 58.78  5.26  5.75 8.13 8.56 9/ 15/ 1999 80.23 76.21  4.19  4.91 7.50 8.16 9/ 16/ 1999 76.74 76.58 0.51 0.14 8.32 8.31 9/ 17/ 1999 86.07 83.84  1.96  2.30 7.66 7.81 9/ 18/ 1999 84.53 82.69  2.23  2.41 5.40 5.52 9/ 19/ 1999 89.66 92.44 3.21 2.97 5.97 5.80 9/ 20/ 1999 92.28 97.99 6.44 6.18 6.44 6.18 Methodology 2: Date MAXOBS1HR NEAR1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 65.02 59.47  8.17  8.69 8.17 8.69 9/ 14/ 1999 62.41 58.04  6.58  7.04 6.80 7.27 9/ 15/ 1999 80.23 74.80  6.05  6.74 6.09 6.78 9/ 16/ 1999 76.74 73.58  3.75  3.93 4.06 4.23 9/ 17/ 1999 86.07 81.69  4.80  5.05 4.90 5.15 9/ 18/ 1999 84.53 81.34  3.81  3.97 4.37 4.52 9/ 19/ 1999 89.66 88.50  1.19  1.23 1.57 1.60 9/ 20/ 1999 92.28 92.30 0.03 0.03 0.07 0.07 Methodology 3: Date MAXOBS1HR CAMXPS1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 65.02 56.66  12.37  13.50 12.37 13.50 9/ 14/ 1999 62.41 54.43  12.27  13.43 12.27 13.43 9/ 15/ 1999 80.23 68.70  13.72  15.15 13.72 15.15 9/ 16/ 1999 76.74 72.67  4.63  5.10 8.08 8.48 9/ 17/ 1999 86.07 76.09  10.79  11.81 12.62 13.61 9/ 18/ 1999 84.53 73.87  12.64  13.67 12.64 13.67 9/ 19/ 1999 89.66 82.71  7.53  8.02 7.53 8.02 9/ 20/ 1999 92.28 91.82  0.16  0.27 3.72 3.77 E 61 Table E 49. Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for Central Texas Monitors ( CAMS 3, 23, 38, 58, 59, 62, 601, 678), September 13   20, 1999. Methodology 1: Date MAXOBS1HR MAXPRD1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 62.13 58.51  5.19  5.66 8.20 8.58 9/ 14/ 1999 64.46 65.12 1.66 1.03 8.35 8.12 9/ 15/ 1999 82.74 83.12 0.82 0.30 6.90 7.07 9/ 16/ 1999 81.99 80.44  0.87  1.34 8.60 8.76 9/ 17/ 1999 89.41 90.38 1.71 1.34 8.06 7.99 9/ 18/ 1999 95.64 93.61  1.81  2.19 6.55 6.78 9/ 19/ 1999 94.96 101.22 6.77 6.01 9.37 8.68 9/ 20/ 1999 95.02 98.41 3.45 3.17 6.50 6.41 Methodology 2: Date MAXOBS1HR NEAR1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 62.13 57.67  6.72  7.14 6.72 7.14 9/ 14/ 1999 64.46 62.22  3.35  3.55 3.45 3.65 9/ 15/ 1999 82.74 79.95  3.11  3.45 3.19 3.54 9/ 16/ 1999 81.99 77.68  4.64  4.96 4.83 5.14 9/ 17/ 1999 89.41 86.33  3.21  3.36 3.35 3.50 9/ 18/ 1999 95.64 91.52  3.96  4.26 4.68 4.98 9/ 19/ 1999 94.96 93.74  1.16  1.20 1.54 1.57 9/ 20/ 1999 95.02 93.85  1.42  1.52 1.77 1.86 Methodology 3: Date MAXOBS1HR CAMXPS1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 62.13 55.28  10.48  11.35 10.48 11.35 9/ 14/ 1999 64.46 58.54  8.70  9.44 9.90 10.61 9/ 15/ 1999 82.74 73.36  10.95  11.97 11.47 12.48 9/ 16/ 1999 81.99 74.65  8.04  8.78 9.77 10.47 9/ 17/ 1999 89.41 80.78  9.18  9.85 9.41 10.09 9/ 18/ 1999 95.64 84.15  11.73  12.92 12.66 13.84 9/ 19/ 1999 94.96 91.66  3.42  3.98 8.47 8.57 9/ 20/ 1999 95.02 87.22  8.04  9.15 9.81 10.90 E 62 Table E 50. Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics (%) for Corpus Christi Monitors  CAMS 4 & 21, September 13   20, 1999. Methodology 1: Date MAXOBS1HR MAXPRD1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 79.00 62.34  19.60  22.29 19.60 22.29 9/ 14/ 1999 83.00 69.91  15.78  17.13 15.78 17.13 9/ 15/ 1999 88.50 79.92  9.58  10.32 9.58 10.32 9/ 16/ 1999 84.00 79.98  4.77  4.91 4.77 4.91 9/ 17/ 1999 83.50 79.11  5.27  5.41 5.27 5.41 9/ 18/ 1999 92.00 99.94 8.64 8.28 8.64 8.28 9/ 19/ 1999 93.00 104.72 13.05 12.10 13.05 12.10 9/ 20/ 1999 84.00 86.88 3.58 3.49 3.58 3.49 Methodology 2: Date MAXOBS1HR NEAR1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 79.00 62.34  19.60  22.29 19.60 22.29 9/ 14/ 1999 83.00 69.91  15.78  17.13 15.78 17.13 9/ 15/ 1999 88.50 79.92  9.58  10.32 9.58 10.32 9/ 16/ 1999 84.00 79.98  4.77  4.91 4.77 4.91 9/ 17/ 1999 83.50 79.11  5.27  5.41 5.27 5.41 9/ 18/ 1999 92.00 92.10 0.11 0.11 0.11 0.11 9/ 19/ 1999 93.00 92.95  0.06  0.06 0.06 0.06 9/ 20/ 1999 84.00 84.13 0.15 0.15 0.15 0.15 Methodology 3: Date MAXOBS1HR CAMXPS1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 79.00 52.75  31.68  38.39 31.68 38.39 9/ 14/ 1999 83.00 62.39  24.76  28.33 24.76 28.33 9/ 15/ 1999 88.50 66.43  24.94  28.49 24.94 28.49 9/ 16/ 1999 84.00 68.27  18.75  20.72 18.75 20.72 9/ 17/ 1999 83.50 71.04  14.92  16.13 14.92 16.13 9/ 18/ 1999 92.00 91.27  0.84  0.95 4.59 4.63 9/ 19/ 1999 93.00 97.16 5.07 4.65 7.92 7.54 9/ 20/ 1999 84.00 72.78  13.28  14.24 13.28 14.24 E 63 Table E 51. Peak Predicted/ observed 8 hour Average Concentrations and Ozone Metrics for CAMS 87, September 13   20, 1999. Methodology 1: Date MAXOBS1HR MAXPRD1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 86.00 51.09  40.59  50.93 40.59 50.93 9/ 14/ 1999 76.00 67.43  11.28  11.95 11.28 11.95 9/ 15/ 1999 92.00 88.02  4.33  4.42 4.33 4.42 9/ 16/ 1999 87.00 84.09  3.34  3.40 3.34 3.40 9/ 17/ 1999 93.00 90.29  2.91  2.96 2.91 2.96 9/ 18/ 1999 94.00 85.76  8.77  9.17 8.77 9.17 9/ 19/ 1999 92.00 91.37  0.68  0.69 0.68 0.69 9/ 20/ 1999 110.00 91.67  16.66  18.18 16.66 18.18 Methodology 2: Date MAXOBS1HR NEAR1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 86.00 51.09  40.59  50.93 40.59 50.93 9/ 14/ 1999 76.00 67.43  11.28  11.95 11.28 11.95 9/ 15/ 1999 92.00 88.02  4.33  4.42 4.33 4.42 9/ 16/ 1999 87.00 84.09  3.34  3.40 3.34 3.40 9/ 17/ 1999 93.00 90.29  2.91  2.96 2.91 2.96 9/ 18/ 1999 94.00 85.76  8.77  9.17 8.77 9.17 9/ 19/ 1999 92.00 91.37  0.68  0.69 0.68 0.69 9/ 20/ 1999 110.00 91.67  16.66  18.18 16.66 18.18 Methodology 3: Date MAXOBS1HR CAMXPS1HR Norm Bias Fractional Bias Norm Error Fractional Error 9/ 13/ 1999 86.00 47.76  44.47  57.18 44.47 57.18 9/ 14/ 1999 76.00 61.97  18.46  20.34 18.46 20.34 9/ 15/ 1999 92.00 76.21  17.16  18.77 17.16 18.77 9/ 16/ 1999 87.00 81.47  6.36  6.56 6.36 6.56 9/ 17/ 1999 93.00 84.99  8.61  9.00 8.61 9.00 9/ 18/ 1999 94.00 76.46  18.66  20.58 18.66 20.58 9/ 19/ 1999 92.00 88.35  3.97  4.05 3.97 4.05 9/ 20/ 1999 110.00 87.70  20.27  22.56 20.27 22.56 E 64 Figure E 33. Normalized Bias for Downwind, Upwind, and Coastal Monitors Calculated using Method 1, September 13 20, 1999. Downwind Monitors:

Upwind Monitors:

Coastal Monitors:  50  40  30  20  10 0 10 20 30 1 2 3 4 5 6 7 8 CAMS 3 CAMS 23 CAMS 38 CAMS 58  50  40  30  20  10 0 10 20 30 1 2 3 4 5 6 7 8 CAMS 59 CAMS 62 CAMS 601 CAMS 678  50  40  30  20  10 0 10 20 30 1 2 3 4 5 6 7 8 CAMS 4 CAMS 21 CAMS 87 E 65 Figure E 34. Normalized Bias for Downwind, Upwind, and Coastal Monitors Calculated using Method 2, September 13 20, 1999. Downwind Monitors:

Upwind Monitors:

Coastal Monitors:  50  40  30  20  10 0 10 20 30 1 2 3 4 5 6 7 8 CAMS 3 CAMS 23 CAMS 38 CAMS 58  50  40  30  20  10 0 10 20 30 1 2 3 4 5 6 7 8 CAMS 59 CAMS 62 CAMS 601 CAMS 678  50  40  30  20  10 0 10 20 30 1 2 3 4 5 6 7 8 CAMS 4 CAMS 21 CAMS 87 E 66 Figure E 35. Normalized Bias for Downwind, Upwind, and Coastal Monitors Calculated using Method 3, September 13 20, 1999. Downwind Monitors:

Upwind Monitors:

Coastal Monitors:  50  40  30  20  10 0 10 20 30 1 2 3 4 5 6 7 8 CAMS 3 CAMS 23 CAMS 38 CAMS 58  50  40  30  20  10 0 10 20 30 1 2 3 4 5 6 7 8 CAMS 59 CAMS 62 CAMS 601 CAMS 678  50  40  30  20  10 0 10 20 30 1 2 3 4 5 6 7 8 CAMS 4 CAMS 21 CAMS 87 E 67 Figure E 36. Fractional Bias for Downwind, Upwind, and Coastal Monitors Calculated using Method 1, September 13 20, 1999. Downwind Monitors:

Upwind Monitors:

Coastal Monitors:  60  50  40  30  20  10 0 10 20 30 1 2 3 4 5 6 7 8 CAMS 59 CAMS 62 CAMS 601 CAMS 678  60  50  40  30  20  10 0 10 20 30 1 2 3 4 5 6 7 8 CAMS 3 CAMS 23 CAMS 38 CAMS 58  60  50  40  30  20  10 0 10 20 30 1 2 3 4 5 6 7 8 CAMS 4 CAMS 21 CAMS 87 E 68 Figure E 37. Fractional Bias for Downwind, Upwind, and Coastal Monitors Calculated using Method 2, September 13 20, 1999. Downwind Monitors:

Upwind Monitors:

Coastal Monitors:  60  50  40  30  20  10 0 10 20 30 1 2 3 4 5 6 7 8 CAMS 3 CAMS 23 CAMS 38 CAMS 58  60  50  40  30  20  10 0 10 20 30 1 2 3 4 5 6 7 8 CAMS 4 CAMS 21 CAMS 87  60  50  40  30  20  10 0 10 20 30 1 2 3 4 5 6 7 8 CAMS 59 CAMS 62 CAMS 601 CAMS 678 E 69 Figure E 38. Fractional Bias for Downwind, Upwind, and Coastal Monitors Calculated using Method 3, September 13 20, 1999. Downwind Monitors:

Upwind Monitors:

Coastal Monitors:  60  50  40  30  20  10 0 10 20 30 1 2 3 4 5 6 7 8 CAMS 3 CAMS 23 CAMS 38 CAMS 58  60  50  40  30  20  10 0 10 20 30 1 2 3 4 5 6 7 8 CAMS 59 CAMS 62 CAMS 601 CAMS 678  60  50  40  30  20  10 0 10 20 30 1 2 3 4 5 6 7 8 CAMS 4 CAMS 21 CAMS 87 E 70 Graphic Analyses EPA also recommends the use of graphics to evaluate model performance ( EPA 1999). These recommendations include the use of time series plots, tile plots, scatter plots and Q Q plots. Results of all four graphics analyses are provided in this section.

Scatter/ Q Q Plots Scatter and Q Q plots were developed using the ENVIRON software program described in the ozone metrics section. Scatter and Q Q data are combined into single plots for each methodology. Results of scatter and Q Q analyses using the three methodologies for data at CAMS 23, CAMS 58, and the group of Central Texas monitors are provided in figures E 39 through E 41. Eight hour average observed/ predicted data points are designated by blue "+" signs. Q Q points are designated by magenta circles. Eight hour scatter/ Q Q plots for other monitors and groups of monitors, as well as one hour plots will be made available to the TCEQ and EPA on compact disc.

Each scatter plot demonstrates moderate to large correlation coefficients, although there are a few observed/ predicted data points that fall outside the ± 20% indicator lines. Quantile points on the Q Q plots follow the 1: 1 reference line fairly well for each monitor and monitor group, with no points falling outside the ± 20% indicator lines. The results from these analyses indicate a high degree of correlation between the paired predicted and observed data. E 71 Figure E 39. Scatter / Q Q Plots for CAMS 23 Calculated using Three Methodologies.

Daily maximum 8 hour ozone near a monitor All sites and all days. Subregion = AACOG CAMS 23 Nearest daily maximum 8 hour ozone.

All sites and all days. Subregion = AACOG CAMS 23 Daily maximum 8 our ozone at monitor.

All sites and all days. Subregion = AACOG CAMS 23 E 72 Figure E 40. Scatter / Q Q Plots for CAMS 58 Calculated using Three Methodologies.

Daily maximum 8 hour ozone near a monitor.

All sites and all days. Subregion = AACOG CAMS 58 Nearest daily maximum 8 hour ozone.

All sites and all days. Subregion = AACOG CAMS 58 Daily maximum 8 hour ozone at monitor.

All sites and all days. Subregion = AACOG CAMS 58 E 73 Figure E 41. Scatter / Q Q Plots for the Eight Central Texas Monitors ( CAMS 3, 23, 38, 58, 59, 62, 601, 678) Calculated using Three Methodologies.

Daily maximum 8 hour ozone near a monitor.

All sites and all days. Subregion = AACOG Central TX Nearest daily maximum 8 hour ozone.

All sites and all days. Subregion = AACOG Cent TX Daily maximum 8 hour ozone at monitor.

All sites and all days. Subregion = AACOG Cent TX E 74 Tile Plots Tile plots provide an indication of where the model is or isn't performing correctly. These plots are visual representations of the model's predictions and provide such information as when and where the model predicts urban plumes. The following tile plots ( figures E 42 through E 47) represent the 8 hour daily maximum concentrations within the modeling domain for each day of the primary episode.

As demonstrated by these plots, urban plumes are replicated well, both in terms of intensity and spatial allocation. Peak ozone concentrations are predicted downwind of city centers and major point sources in these tile plots. E 75 Figure E 42. Predicted Daily Maximum 8 hour Ozone Concentrations within the 4 km Subdomain for Wednesday, September 15, 1999. Figure E 43. Predicted Daily Maximum 8 hour Ozone Concentrations within the 4 km Subdomain for Thursday, September 16, 1999. E 76 Figure E 44. Predicted Daily Maximum 8 hour Ozone Concentrations within the 4 km Subdomain for Friday,

September 17, 1999. Figure E 45. Predicted Daily Maximum 8 hour Ozone Concentrations within the 4 km Subdomain for Saturday, September 18, 1999. E 77 Figure E 46. Predicted Daily Maximum 8 hour Ozone Concentrations within the 4 km Subdomain for Sunday,

September 19, 1999. Figure E 47. Predicted Daily Maximum 8 hour Ozone Concentrations within the 4 km Subdomain for Monday,

September 20, 1999. E 78 Diagnostic Evaluations Diagnostic tests are conducted throughout model development to assist with identifying and troubleshooting performance problems. An important method of conducting diagnostic evaluations involves the use of sensitivity tests. These tests are conducted by perturbing various types of model input. For example, sensitivity tests were conducted on the 1999 episode by altering the model's boundary conditions. As a result of these tests, some boundary conditions were modified from default values to measurements collected during studies of background concentrations ( described in appendix B).

Sensitivity tests may also be used to evaluate the base and future case runs to ensure the model responds appropriately to changes in emissions inputs and to estimate the impact of control strategies. This section presents the results of conducting sensitivity runs on the 1999 base case as a means of assessing the responsiveness of the model and providing an indication of which type of emissions reductions may be most useful for improving air quality in the San Antonio region.

Zero out Runs: Urban Areas One sensitivity evaluation involved removing the anthropogenic VOC and NOx emissions for the 8 county Houston area from the photochemical model. Similarly, two other sensitivity runs were conducted by removing anthropogenic precursor emissions for the 5 county Austin area and 2 county Corpus Christi area from the model. All three of these urban areas were upwind of the SAER on at least one September 1999 episode day.

The results of removing anthropogenic emissions were averaged over the 6 day primary episode period ( September 15   20th) for each of the three sensitivity runs. Figure E 48 provides the estimated average reductions in ozone concentrations within the SAER after removing the anthropogenic emissions for Austin, Corpus Christi, and Houston from the model. As indicated, removing Houston's precursor emissions had the greatest impact on estimated ozone concentrations in the San Antonio region ( 2.72 ppb), followed by Corpus Christi ( 0.64 ppb), and Austin ( 0.27 ppb).

These outcomes are consistent with the meteorological conditions that existed during the episode. Although Austin is closer in proximity to San Antonio, back trajectory information indicates that wind parcels traveled through Houston and Corpus Christi more often during the September 1999 episode than through Austin. In addition, Houston is a much larger source of precursor emissions than either Corpus Christi or Austin. E 79 Figure E 48. Predicted Reduction in Ozone Concentrations (%) in the SAER after Removing Austin, Corpus Christi, and Houston Anthropogenic NOx and VOC Emissions from the Photochemical Model. ( Average reductions for September 15   20, 1999).

Incremental Removal of VOC and NOx Precursors Across the board sensitivity runs were conducted by removing 25%, 50%, 75%, and 100% of the local ( 4 county SAER) NOx emissions, VOC emissions, and combinations of the two, from the CAMx Run 17b model. Figures E 49 through E 54 provide the results of the across the board reduction runs for each day of the primary episode. These graphs provide the model's ozone concentration predictions at CAMS 23, the controlling monitor, as the result of reducing local precursor emissions, compared to the monitor's design value.

Due to time constraints, VOC/ NOx reduction analyses were not conducted on the final run, CAMx Run 18. However, several precursor sensitivity runs were conducted on a prior version of the September 1999 model, CAMx Run 17b. The primary difference between CAMx Run 17b and CAMx Run 18, for the 1999 base cases, 4 was the use of a refined MOBILE6 on road EI in the latter model, as described in section 3.4 of the Executive Summary. Rerunning all the sensitivity tests again on Run 18 would have added an enormous amount of work. Based upon experience, it was assumed that the 4 The 2007 projection developed from CAMx Run 18a incorporates a refined regional EI ( described in Section 3.6 of the Executive Summary); however, the regional EIs for Runs 17b and 18a 1999 base cases are identical. 2.72 parts per billion 0.64 parts per billion 0.27 parts per billion 0.0% 0.5% 1.0% 1.5% 2.0% 2.5% 3.0% 3.5% Austin Removed Corpus Removed Houston Removed Percent Reduction in Ozone E 80 general findings and directional guidance determined from previous runs would remain stable with relatively small emissions adjustments.

As indicated by the VOC/ NOx sensitivity runs, reductions of NOx, VOC, or a combination of NOx and VOC effectively reduced ozone concentrations at the 25% reduction level on most episode days. An exception occurs on September 17th, when the model predicts a NOx reduction disbenefit as the result of removing 25% and 50% of the anthropogenic SAER emissions. Because of the NOx reduction disbenefit predicted on the 17th and 20th, reducing VOC emissions alone, not a combination of VOC and NOx reductions, was the most effective method of reducing ozone concentrations on those episode days. Another point that is evident from these analyses is that, in general, VOC reductions were more effective than NOx reductions over the range of controls required to demonstrate attainment.

Figure E 49. Predicted Ozone Concentrations at CAMS 23 after Removing Local ( 4 county SAER) NOx and VOC Emissions from Simulation 17b, September 15, 1999.

55 70 85 100 0 25% 50% 75% 100% Anthropogenic Emission Reductions ( percentage) Ozone Concentration ( ppb)

NOx Reduction VOC Reduction NOx & VOC Reduction 8 hour standard  85 ppb E 81 Figure E 50. Predicted Ozone Concentrations at CAMS 23 after Removing Local ( 4 county SAER) NOx and VOC Emissions from Simulation 17b, September 16, 1999.

Figure E 51. Predicted Ozone Concentrations at CAMS 23 after Removing Local ( 4 county SAER) NOx and VOC Emissions from Simulation 17b, September 17, 1999. 55 70 85 100 0 25% 50% 75% 100% Anthropogenic Emission Reductions ( percentage) Ozone Concentration ( ppb)

NOx Reduction VOC Reduction NOx & VOC Reduction 8 hour standard  85 ppb 55 70 85 100 0 25% 50% 75% 100% Anthropogenic Emission Reductions ( percentage) Ozone Concentration ( ppb)

NOx Reduction VOC Reduction NOx & VOC Reduction 8 hour standard  85 ppb E 82 Figure E 52. Predicted Ozone Concentrations at CAMS 23 after Removing Local NOx and VOC Emissions from Simulation 17b, September 18, 1999.

Figure E 53. Predicted Ozone Concentrations at CAMS 23 after Removing Local NOx and VOC Emissions from Simulation 17b, September 19, 1999. 55 70 85 100 0 25% 50% 75% 100% Anthropogenic Emission Reductions ( percentage) Ozone Concentration ( ppb)

NOx Reduction VOC Reduction NOx & VOC Reduction 8 hour standard  85 ppb 55 70 85 100 0 25% 50% 75% 100% Anthropogenic Emission Reductions ( percentage) Ozone Concentration ( ppb)

NOx Reduction VOC Reduction NOx & VOC Reduction 8 hour standard  85 ppb E 83 Figure E 54. Predicted Ozone Concentrations at CAMS 23 after Removing Local NOx and VOC Emissions from Simulation 17b, September 20, 1999.

COMPARISONS BETWEEN UT AUSTIN AND AACGO 1999 BASE CASES Although the original September 1999 model was developed by ENVIRON and refined through a collaboration between ENVIRON and UT Austin ( meteorological model and air quality input refinements), the model was eventually provided to the NNA partners ( or their contractors) for further modifications. These modifications included refinement of the emissions inventory inputs, development of the future case, and clean air strategy analyses. Because the model was modified by more than one agency during this process, there was a concern that the various agencies' models would become dissimilar and provide different predictions for the base case, future case, and control strategy runs.

A great amount of effort was spent ensuring that the Austin and San Antonio base and future cases contained identical input. Often this involved discussions between the two agencies, as well as TCEQ, regarding the most appropriate EI data for local and regional areas. Discrepancies in emissions inputs were corrected prior to the final AACOG run and the final UT run.

An analysis was conducted by AACOG staff to determine any differences between the final 1999 run refined by UT Austin and the final run refined by AACOG, based on ozone predictions near two Austin monitors. The results of these analyses are provided in table E 52. The table lists peak predictions within the 7x7 array of cells near the Murchison and Audubon monitors for the AACOG ( highlighted in yellow) and UT 1999 base cases.

As shown, the differences between predictions by AACOG's final run ( labeled 1999_ sos. f) and UT's final run ( labeled 1999_ v3) are insignificant. With regards to the Murchison monitor, the average difference ( six episode days) in ozone concentrations between the two 1999 base cases was 0.00 ppb, while the average difference at the 55 70 85 100 0 25% 50% 75% 100% Anthropogenic Emission Reductions ( percentage) Ozone Concentration ( ppb)

NOx Reduction VOC Reduction NOx & VOC Reduction 8 hour standard  85 ppb E 84 Audubon monitor was 0.05 ppb. The 2007 future cases developed by AACOG and UT Austin were similarly compared. These comparisons are provided in appendix G.

The performance of the September 1999 photochemical model was thoroughly analyzed and tested by AACOG staff, both in terms of 1 hour and 8 hour predictions, using a variety of EPA recommended performance evaluations. Because the model is being used by other Texas NNA regions, performance analyses have been conducted by other agencies as well. Each has concluded that the September 1999 model meets EPAacceptance criteria for attainment demonstration modeling. Furthermore, comparisons between the 1999 base case refined by AACOG and the 1999 base case refined by UT Austin provides additional, independent verification of the quality of the model in terms of performance.

Table E 52. Comparison of Predicted Peak 8 hour Concentrations for Final UT and AACOG Base Case Runs.

Monitor UT 1999_ v3 AACOG 1999_ sos. f Average Difference Days Date MURCHISON 84.6 84.6 0.00 6 9/ 15   9/ 20 AUDU 81 80.9 0.05 6 9/ 15   9/ 20 Monitor UT 1999_ v3 AACOG 1999_ sos. f Daily Difference Days Date MURC 77.8 77.8 0.0 1 9/ 15 MURC 75.5 75.4 0.1 1 9/ 16 MURC 86.8 86.7 0.1 1 9/ 17 MURC 84.5 84.4 0.1 1 9/ 18 MURC 89.6 89.7  0.1 1 9/ 19 MURC 93.6 93.6 0.0 1 9/ 20 AUDU 76.2 76.1 0.1 1 9/ 15 AUDU 78.2 78.2 0.0 1 9/ 16 AUDU 87.4 87.4 0.0 1 9/ 17 AUDU 84.5 84.4 0.1 1 9/ 18 AUDU 89.4 89.5  0.1 1 9/ 19 AUDU 70.1 70.2  0.1 1 9/ 20 E 85 REFERENCES Emery, C. A., Tai, E., Wilson, G. M., Yarwood, G. ( August 6, 2002). Development of a Joint CAMx Photochemial Modeling Database for the Four Southern Texas . Near Non Attainment Areas. Novato, CA: prepared for the Texas Near Non Attainment Areas through the Alamo Area Council of Governments by ENVIRON International Corporation.

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