Final Report — September 2004 

Big Bend

Regional

Aerosol and

Visibility

Observational Study

PRIMARY AUTHORS 

 Marc L. Pitchford National Oceanic and Atmospheric Administration, Las Vegas, NV

 Ivar Tombach Camarillo, CA

 Michael Barna Colorado State University, Ft. Collins, CO

 Kristi A. Gebhart National Park Service, Air Resources Division, Ft. Collins, CO

 Mark C. Green Desert Research Institute, Las Vegas, NV

 Eladio Knipping EPRI, Palo Alto, CA

 Naresh Kumar EPRI, Palo Alto, CA

 William C. Malm National Park Service, Air Resources Division, Ft. Collins, CO

 Betty Pun Atmospheric and Environmental Research, Inc., San Ramon, CA

 Bret A. Schichtel National Park Service, Air Resources Division, Ft. Collins, CO

 Christian Seigneur Atmospheric and Environmental Research, Inc., San Ramon, CA

CONTRIBUTING AUTHORS 

W. Pat Arnott 

Desert Research Institute, Reno, NV 

Lowell Ashbaugh 

University of California, Davis CA 

Thomas Cahill 

University of California, Davis CA 

Jeffrey L. Collett, Jr. 

Colorado State University, Ft. Collins, CO 

Derek Day 

Colorado State University, Ft. Collins, CO 

Stuart Dattner 

Texas Commission on Environmental Quality, 

Austin, TX 

Russell N. Dietz 

Brookhaven National Laboratory, Upton, NY

Bethany Georgoulias 

Texas Commission on Environmental Quality, 

Austin, TX 

Jenny Hand 

Colorado State University, Ft. Collins, CO 

Sonia Kreidenweis 

Colorado State University, Ft. Collins, CO 

Hampden D. Kuhns 

Desert Research Institute, Reno, NV 

Fernando Mercado 

Texas Commission on Environmental Quality, 

Austin, TX

Nelson Seaman 

Pennsylvania State University, 

University Park, PA

David Stauffer 

Pennsylvania State University, 

University Park, PA 

Jeffrey M. Vukovich 

Carolina Environmental Program, 

University of North Carolina, Chapel Hill, NC 

Thomas B. Watson 

National Oceanic and Atmospheric Admin., 

Air Resources Laboratory, Idaho Falls, ID 

Shiang-Yuh Wu 

Atmospheric and Environmental Research, Inc.,

San Ramon, CA 

SPONSORING AND CONTRIBUTING ORGANIZATIONS 

Texas Commission on 

Environmental Quality 
Note to Readers 

This report relies extensively on color its charts and figures. Although the charts in the 

report are designed so that their meanings can generally be discerned from a black-and-white 

copy, full understanding of the information in some complex figures can only be achieved 

when they are viewed in color. Adobe Acrobat files containing the report and appendix are 

available on compact disc (CD) at the back of the original printed versions of the report and 

from the IMPROVE web site at http://vista.cira.colostate.edu/improve/. 
Final Report — September 2004 

i

Preface 

 The following is a report about the results of a study concerning the causes of 

visibility impairment at Big Bend National Park (NP) in west Texas. The study was 

prompted by observations in the early 1990s that visibility at the Park was frequently 

degraded and was apparently getting worse.

 A preliminary study was sponsored by the U.S. Environmental Protection Agency 

(EPA), the National Park Service (NPS), and governmental agencies from Mexico. This 

preliminary study was conducted in 1996 and a report of its findings released in January 

1999. The findings indicated that fine particulate sulfur compounds played a large role in 

observed impairment and that there was apparent transport of particulate sulfur compounds 

from sources in Mexico and the U.S. The preliminary report concluded that, in order to get a 

better understanding of the contributors to impairment at Big Bend NP, an enhanced study 

would be necessary that expanded the scope of the field measurement activities and 

expanded the spatial domain of the preliminary study, particularly to the northeast, south, and 

into the Gulf of Mexico.

 The EPA, the NPS, and the Texas Commission on Environmental Quality (TCEQ)

comprised the Steering Committee for the enhanced study, the Big Bend Regional Aerosol 

and Visibility Observational (BRAVO) Study. In April 1999, Mexico elected not to 

participate in the Study, which resulted in the Study being unable to gather ambient 

monitoring and atmospheric tracer release data in Mexico. Although this was a disappointing 

development, the monitoring and atmospheric tracer protocols were altered to maximize data 

collection in the U.S. border area nearest Mexico. The BRAVO Technical Sub-committee 

designed and directed the field-measurement portion of this study that ran from July through 

October 1999, and interpretation and analyses of these field data were completed in early 

2004. 

The BRAVO Study was designed as an investigation of the causes of haze at Big 

Bend National Park, but not as an assessment of regulatory options. The Study constituted 

one of the largest and most comprehensive visibility field studies and air quality modeling 

evaluation efforts conducted in the U.S. It used state-of-the-science monitoring, air quality 

modeling, and laboratory and statistical analyses and involved over 30 researchers from 

research and academic institutions throughout the U.S. It used inert atmospheric tracers over 

a huge geographic scale and made use of the best available air emissions input data. 

Evaluation of the collected data continued for over three years after the end of the 1999 field 

study.

 While the Steering Committee was responsible for the ultimate publication of the 

BRAVO final report, the Steering Committee relied upon the BRAVO Technical Subcommittee to conduct or sponsor detailed analyses of the field data and source-region 

attribution analyses and to prepare the final report. Findings presented in the final report 

were thoroughly discussed by the Steering Committee, the Technical Sub-committee, and a 
Final Report — September 2004 

ii

Non-governmental Sub-committee consisting of industry and environmental advocacy 

groups.

 The final report provides estimates of the contributions of broad geographic regions 

to visibility impairment at the Park during the study period. Contributions from the eastern 

U.S., eastern Texas, and Mexico were noted. Because of the relative proximity of the 

Carbón I and II power plants to the Park, contributions specific to those facilities were 

estimated in this analysis. Such source-specific calculations were not made for other sources 

in the study domain. Of particular significance was the indication that sources over a broad 

geographic region play roles in the observed visibility impairment in the Park, suggesting too 

that the solution should be based on international and regional, multi-State strategies.

 The confidence in these results notwithstanding, it must be emphasized that the 

endorsement of these findings by the BRAVO Steering Committee is made with the 

understanding that uncertainties exist and that analysis tools, no matter how sophisticated, 

only approximate atmospheric transport and chemical reactions. However, the Steering 

Committee is confident that the results of the study have been fairly presented with the 

concomitant caveats.

 The BRAVO Steering Committee wishes to acknowledge the commitment and 

contribution of all that participated in this study and the preparation of this report. Our 

understanding of the science of the effects of atmospheric aerosol on visibility has been 

greatly expanded, as has our understanding of the causes of visibility impairment at Big Bend 

NP.

As the Steering Committee for the BRAVO Study:

Mark A. Scruggs, Ph.D. 

National Park Service 

Herbert W. Williams 

Texas Commission on Environmental Quality 

James W. Yarbrough 

U.S. Environmental Protection Agency 
Final Report — September 2004 

iii

Acknowledgments 

 The BRAVO Study could not have been accomplished without the enthusiastic 

support of participant organizations and individuals. From the initial planning in 1997, 

through the four-month ambient monitoring program in 1999, to the assessment process, and 

culminating in 2004 with the preparation of the final report, this study has been fortunate to 

include many talented and dedicated individuals from a number of organizations functioning 

together as a team. We are indebted to both the individuals for their thoughtful and energetic 

participation, and to their parent organizations that permitted and encouraged involvement by 

their staff. 

 The list of organizations that participated in the BRAVO Study includes 

• Sponsors: U.S. Environmental Protection Agency, National Park Service, and the 

Texas Commission on Environmental Quality; 

• Contributors: EPRI, and the National Oceanic and Atmospheric Administration - 

Air Resources Laboratory; 

• Research Institutions and Universities: University of California - Davis, Desert 

Research Institute and the Cooperative Institute for Atmospheric Science and 

Terrestrial Applications at the University of Nevada, Cooperative Institute for 

Research in the Atmosphere at Colorado State University, Pennsylvania State 

University, Carolina Environmental Program at the University of North Carolina, 

and Brookhaven National Laboratory; 

• Consulting Firms: Atmospheric and Environmental Research, Inc, Air Resource 

Specialists, Inc, and Aerosol Dynamics; and 

• Stakeholders: the Environmental Defense, the Sierra Club, American Electric 

Power, TXU, and Reliant Energy. 

 The list below includes the individual participants that are not already acknowledged 

on the cover page as authors. It takes a lot of good people to accomplish a program of this 

magnitude and we were lucky to have a great team. 

• Ramon Alvarez ................Environmental Defense, Austin, TX 

• Thomas N. Braverman.....USEPA, Research Triangle Park, NC 

• Pete Breitenbach ..............Texas Commission on Environ. Quality, Austin, TX 

• Judith C. Chow.................Desert Research Institute, Reno, NV 

• N. N. Dharmarajan...........American Electric Power, Dallas, TX 

• Bright Dornblazer ............Texas Commission on Environ. Quality, Austin, TX 

• Robert C. Eldred ..............University of California, Davis, CA 

• Vic Etyemezian................Desert Research Institute, Las Vegas, NV 

• Miguel Flores...................USEPA Region VI, Dallas, TX 
Final Report — September 2004 

iv

Acknowledgments (continued)

• Brian Foster......................Texas Commission on Environ. Quality, Austin, TX 

• Michael George................National Park Service, Austin, TX 

• Eric Gribbin .....................Texas Commission on Environ. Quality, Austin, TX 

• Mike Hannigan.................Colorado State University, Ft. Collins, CO 

• David Harper....................Texas Commission on Environ. Quality, Austin, TX 

• Susanne Hering ................Aerosol Dynamics, Berkeley, CA 

• Richard Karp....................Minerals Management Service, New Orleans, LA 

• John Kush.........................Reliant Energy, Houston, TX 

• Taeyoung Lee...................Colorado State University, Ft. Collins, CO 

• Chuck McDade ................University of California, Davis, CA 

• Jocelyn Mellberg..............Texas Commission on Environ. Quality, Austin, TX 

• Shannon Minto.................Texas Commission on Environ. Quality, Austin, TX 

• John Molenar ...................Air Resource Specialists, Ft. Collins, CO 

• Greg Newman ..................Reliant Energy, Houston, TX 

• Jill Riley...........................Colorado State University, Ft. Collins, CO 

• Dick Robertson ................TXU, Dallas, TX 

• Mark Scruggs...................National Park Service, Denver, CO 

• Eli Sherman......................Colorado State University, Ft. Collins, CO 

• Usha Turner .....................TXU, Dallas, TX 

• John Vimont.....................National Park Service, Denver, CO 

• John G. Watson................Desert Research Institute, Reno, NV 

• Herb Williams..................Texas Commission on Environ. Quality, Austin, TX 

• James W. Yarbrough........USEPA Region VI, Dallas, TX 
Final Report — September 2004 

v

Table of Contents 

 

Page

Preface........................................................................................................................................ i 

Acknowledgments.................................................................................................................... iii 

Table of Contents.......................................................................................................................v 

List of Figures.......................................................................................................................... xi 

List of Tables ...........................................................................................................................xx 

List of Abbreviations and Acronyms................................................................................... xxiv 

EXECUTIVE SUMMARY .................................................................................................ES-1 

1. TECHNICAL OVERVIEW ........................................................................................... 1-1 

Which are the major aerosol components contributing to haze at Big Bend NP 

throughout a year?............................................................................................ 1-2 

How does the composition of haze vary at Big Bend National Park throughout a 

year during the haziest days? ........................................................................... 1-4 

How does airflow to Big Bend National Park vary throughout the year?.................... 1-5 

Where are emission sources that may cause particulate sulfate compounds that 

contribute to Big Bend haze? ........................................................................... 1-7 

How does the composition of haze vary at Big Bend National Park during the 

four-month BRAVO Study period? ................................................................. 1-9 

How did different source regions contribute to particulate sulfate compounds 

affecting haze levels at Big Bend National Park during the BRAVO 

Study period?.................................................................................................. 1-10 

How did different source regions contribute to haze levels at Big Bend National 

Park during the BRAVO Study period?......................................................... 1-14 

How applicable are the particulate sulfate attribution results for the BRAVO 

Study period to other years or times of year?................................................. 1-16 

2. INTRODUCTION .......................................................................................................... 2-1 

2.1 Setting................................................................................................................. 2-1

2.2 Study Goals......................................................................................................... 2-3 

2.3 Management ....................................................................................................... 2-3 

2.4 Preliminary Study ............................................................................................... 2-3 

2.5 Seasonality of the Aerosol Components of Light Extinction ............................. 2-5 

3. STUDY DESIGN AND IMPLEMENTATION............................................................. 3-1 

3.1 Selection of the Study Period ............................................................................. 3-1 

3.2 Use of Synthetic Tracers..................................................................................... 3-2 

3.2.1 Tracer Release ...................................................................................... 3-2 

3.2.2 Tracer Monitoring ................................................................................ 3-5 

3.3 Aerosol and Gaseous Measurements.................................................................. 3-6 

3.4 Optical Measurements ...................................................................................... 3-11 
Final Report — September 2004 

vi

Table of Contents (continued)

Page

3.5 Meteorological Measurements.......................................................................... 3-11 

3.6 Source Characterization.................................................................................... 3-13 

3.7 Aircraft Measurements ..................................................................................... 3-14 

4. EMISSIONS INFORMATION ...................................................................................... 4-1 

4.1 Emission Inventory............................................................................................. 4-1 

4.2 Emissions Modeling ........................................................................................... 4-5 

4.3 Emissions Inventory Assessment ....................................................................... 4-7 

5. THE ATMOSPHERIC ENVIRONMENT OBSERVED AT BIG BEND 

NATIONAL PARK DURING THE BRAVO STUDY ................................................. 5-1 

5.1 Particulate Matter Characterization by the Routine Measurement Network...... 5-1 

5.1.1 Particulate Matter Temporal and Spatial Characteristics..................... 5-1 

5.1.2 Properties of Particulate Matter at Big Bend National Park ................ 5-4 

5.2 Detailed Characterization of the Particulate Matter at Big Bend National 

Park................................................................................................................... 5-6 

5.2.1 Ionic Composition of Big Bend Particulate Matter.............................. 5-7 

5.2.2 Short Time Resolution Sulfate Concentrations at Big Bend................ 5-8 

5.2.3 Organic Source Markers in Big Bend Aerosol................................... 5-10 

5.2.4 Particle Size Distribution ................................................................... 5-12 

5.2.5 Very Fine PM as a Source Tracer ...................................................... 5-13 

5.3 Characterization of Optical Conditions at Big Bend National Park................. 5-15 

5.3.1 Light Absorption Measurements........................................................ 5-15 

5.3.2 Optical Measurements of the Big Bend Atmosphere......................... 5-19 

5.4 Meteorology During the BRAVO Study .......................................................... 5-21 

5.5 Perfluorocarbon Tracer Experiment Findings .................................................. 5-26 

5.5.1 Continuous Tracer Results ................................................................. 5-26 

5.5.2 Analysis of Timing Tracer Data......................................................... 5-30 

6. ANALYSIS OF BRAVO MEASUREMENTS.............................................................. 6-1 

6.1 Collocated Measurements................................................................................... 6-1 

6.2 Fine PM Mass Closure........................................................................................ 6-3 

6.3 Extinction Budget ............................................................................................... 6-4 

6.3.1 Light Scattering by Dry Particles ......................................................... 6-4 

6.3.2 Species Contributions to Light Extinction ........................................... 6-5 

6.4 Evaluation of the IMPROVE Equation for Estimating Light Extinction at 

Big Bend National Park.................................................................................... 6-8 

7. STUDY PERIOD REPRESENTATIVENESS .............................................................. 7-1 

7.1 Meteorology........................................................................................................ 7-1 

7.2 Transport Climatology........................................................................................ 7-4 

7.3 Aerosol and Light Extinction.............................................................................. 7-9 

7.4 Assessment of BRAVO Study Representativeness .......................................... 7-19 
Final Report — September 2004 

vii

Table of Contents (continued)

Page

8. ATTRIBUTION ANALYSIS AND MODELING METHODS .................................... 8-1 

8.1 Data Analysis Methods....................................................................................... 8-1 

8.1.1 Tracer Methods – TAGIT .................................................................... 8-1 

8.1.2 Empirical Orthogonal Function Analysis............................................. 8-3 

8.1.3 Factor Analysis..................................................................................... 8-4 

8.2 Meteorological Fields ......................................................................................... 8-4 

8.2.1 EDAS ................................................................................................... 8-5 

8.2.2 FNL ...................................................................................................... 8-5 

8.2.3 MM5..................................................................................................... 8-6 

8.3 Trajectory-Based Analyses................................................................................. 8-7 

8.3.1 ATAD Trajectories............................................................................... 8-7 

8.3.2 HYSPLIT Trajectories ......................................................................... 8-8 

8.3.3 CAPITA Monte Carlo Trajectories ...................................................... 8-8 

8.3.4 Ensemble Air-Mass History Analyses ................................................. 8-9 

8.3.5 Trajectory Mass Balance (TrMB) ........................................................ 8-9 

8.3.6 Forward Mass Balance Regression (FMBR) ..................................... 8-12 

8.4 Air Quality Simulation Modeling..................................................................... 8-14 

8.4.1 CAPITA Monte Carlo ........................................................................ 8-14 

8.4.2 REMSAD ........................................................................................... 8-15 

8.4.3 CMAQ................................................................................................ 8-16 

8.4.4 Synthesized REMSAD and CMAQ ................................................... 8-18 

8.5 Attribution Source Regions .............................................................................. 8-18 

8.6 Visualization of Spatial Patterns....................................................................... 8-21 

9. EVALUATION OF SOURCE ATTRIBUTION METHODS ....................................... 9-1 

9.1 Evaluation of Simulations of Meteorological Fields .......................................... 9-1 

9.1.1 Evaluation of MM5 Surface Meteorology Simulations ....................... 9-2 

9.1.2 Comparison of MM5, EDAS, and FNL Wind Fields to Radar 

Wind Profiler Measurements ............................................................... 9-5 

9.1.3 Evaluation of REMSAD/MM5 Simulations of Precipitation and 

Clouds................................................................................................... 9-9 

9.2 Sensitivity of Trajectories to Wind Fields........................................................ 9-13 

9.2.1 Effect of Wind Field Choice .............................................................. 9-14 

9.2.2 Effect of Trajectory Model Choice .................................................... 9-15 

9.2.3 Effect of Back Trajectory Start Height .............................................. 9-16 

9.2.4 Effect of Using FNL Winds in October ............................................. 9-17 

9.3 Evaluation of the Trajectory Mass Balance (TrMB) Method using 

Perfluorocarbon Tracer Measurements .......................................................... 9-17 

9.4 Evaluation of the CAPITA Monte Carlo Model Using Perfluorocarbon 

Tracer Measurements ..................................................................................... 9-20 
Final Report — September 2004 

viii

Table of Contents (continued)

Page

9.5 Evaluation of the Forward Mass Balance Regression (FMBR) Method 

Using Perfluorocarbon Tracer Measurements................................................ 9-25 

9.5.1 Retrieval of Tracer Release Locations and Rates............................... 9-25 

9.5.2 Source Apportionment of Tracer Concentrations .............................. 9-27 

9.5.3 Discussion of FMBR Tracer Evaluation ............................................ 9-28 

9.6 Evaluation of the Tracer Mass Balance (TrMB) Method Using 

REMSAD-Modeled Sulfate Concentrations .................................................. 9-28 

9.7 Evaluation of the Forward Mass Balance Regression (FMBR) Method 

Using REMSAD-Modeled Sulfate Concentrations........................................ 9-32 

9.8 Evaluation of REMSAD Simulations of Perfluorocarbon Tracers................... 9-34 

9.9 Evaluation of REMSAD Simulations of SO2, and Sulfate Measurements....... 9-39 

9.10 Evaluation of CMAQ Simulations of Perfluorocarbon Tracers ....................... 9-45 

9.11 Evaluation of CMAQ Simulations of SO2, Sulfate, and Other Aerosol 

Components.................................................................................................... 9-51 

9.11.1 Development of Base Case ................................................................ 9-51 

9.11.2 Base Case Performance...................................................................... 9-53 

9.11.3 Discussion of CMAQ-MADRID Performance .................................. 9-63 

9.12 Synthesis Inversion – Merging Modeled Source Apportionment Results 

and Receptor Data .......................................................................................... 9-64 

9.13 Conclusions Concerning Performance of the Source Attribution Methods ..... 9-66 

10. SOURCE ATTRIBUTIONS BY AMBIENT DATA ANALYSIS.............................. 10-1 

10.1 Sulfur Attributions via TAGIT ......................................................................... 10-1 

10.2 Attribution of PM2.5 Components via Exploratory Factor Analysis................. 10-3 

10.3 Attribution of Big Bend Particulate Sulfur and Soil via EOF Analysis ........... 10-7 

10.4 Transport Patterns to Big Bend during Periods of High and Low Sulfur 

Concentrations.............................................................................................. 10-11 

10.5 Attribution of Big Bend Particulate Sulfur via Trajectory Mass Balance 

(TrMB) ......................................................................................................... 10-15 

10.6 Attribution of Big Bend Sulfate via Forward Mass Balance Regression 

(FMBR) ........................................................................................................ 10-18 

11. SOURCE ATTRIBUTIONS BY AIR QUALITY MODELING................................. 11-1 

11.1 Sulfate Attribution via REMSAD..................................................................... 11-1 

11.2 Sulfate Attribution via CMAQ-MADRID...................................................... 11-11 

11.3 Refined Sulfate Attribution using Synthesized Modeling Approaches.......... 11-17 

12. ATTRIBUTION RECONCILIATION, CONCEPTUAL MODEL, AND 

LESSONS LEARNED ................................................................................................. 12-1 

12.1 Introduction....................................................................................................... 12-1 

12.2 Phase I: Tracer Screening and Evaluation........................................................ 12-3 

12.3 Phase II: Initial Application.............................................................................. 12-5 

12.4 Refined Attribution Approaches....................................................................... 12-8 
Final Report — September 2004 

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Table of Contents (continued)

Page

12.5 Haze Source Attribution ................................................................................. 12-12 

12.6 Big Bend Haze Conceptual Model ................................................................. 12-15 

12.7 Lessons Learned and Recommendations........................................................ 12-19 

12.7.1 Overall Design and Management..................................................... 12-20 

12.7.2 Field Measurements ......................................................................... 12-21 

12.7.3 Source Attribution Approaches........................................................ 12-22 

12.7.4 Results .............................................................................................. 12-24 

13. REFERENCES............................................................................................................. 13-1

APPENDIX.......................................................... CD-ROM disc on the last page of this report 

A.1 Baylor University (2000). 1999 Executive Summary: Airborne Pollution 

Monitoring Services. ................filename: A1_Baylor2000AircraftMeasurements.pdf

A.2 Cahill, T.A., et al. (2003). UC Davis DELTA Group Final report to 

BRAVO on the project – Very fine (0.26 > Dp > 0.09 μm) Silicon plus 

Sulfur as a Tracer of Coal Fired Power Plants during BRAVO. 

....................................................... filename: A2_Cahill2003UCDavisSiliconSulfur.pdf

A.3 Georgoulias, B. (2003). Was BRAVO Meteorology “Typical”? 

..........................................................filename: A3_Georgoulias2003Meteorology.pdf

A.4 Georgoulias, B., et al. (2003). Evaluation of the Reconstruction Equation 

at Big Bend during BRAVO & Using Factor Analysis to Relate Aerosol 

Concentrations to Light Extinction. 

........................................................... filename: A4_Georgoulias2003ReconEqFA.pdf

A.5 Kuhns, H., et al. (2003). Big Bend Regional Aerosol and Visibility 

Observational (BRAVO) Study Emissions Inventory. 

.......................................................................filename: A5_Kuhns2003EmissInv.pdf

A.6 Mercado, F., et al. (2004). Application of Factor Analysis to the BRAVO 

Dataset. .............................................filename: A6_Mercado2004FactorAnalysis.pdf

A.7 Pun et al. (2004). Modeling Analysis of the Big Bend Regional Aerosol 

Visibility Observational (Bravo) Study. 

.......................................................................... filename: A7_Pun2004Modeling.pdf

A.8 Schichtel et al. (2004). Big Bend Regional Aerosol and Visibility 

Observational (BRAVO) Study Results: Air Quality Data and Source 

Attribution Analyses Results from the National Park Service / 

Cooperative Institute for Research in the Atmosphere. 

...............................................................filename: A8_Schichtel2004CIRAReport.pdf

A.8.1 REMSAD Animations 

.................................................... filenames: A8_so2_oct1999.avi

......................................................................................A8_so4_oct1999.avi

...........................................................................A8_so4_clouds_oct1999.avi

........................................................................A8_winds_clouds_oct1999.avi
Final Report — September 2004 

x

Table of Contents (continued)

Page

A.8.2 Backward Trajectories 

................................. filenames: A8_Appendix4b_CAPITAMC_Trajectories.ppt

......................................................A8_Appendix4c_HYSPLIT_Trajectories.ppt

..........................................................A8_Appendix4d_ATAD_Trajectories.ppt

A.8.3 Daily Maps of Fine Particulate Sulfur Concentrations 

......................................... filename: A8_Appendix8b_DailySulfurPatterns.ppt

A.9 Seaman, N.L.; and Stauffer, D.R. (2003). Final Report to Electric Power 

Research Institute Contract EP-P3883/C1886 for MM5 Modeling in 

support of the Big Bend Regional Aerosol and Visibility Observation 

Study (BRAVO). ............................... filename: A9_Seaman2003MM5Modeling.pdf

A.10 Vukovich, J. (2002). Technical Report: Emissions Processing for the Big 

Bend Regional Aerosol and Visibility Observational (BRAVO) Study. 

...........................................................filename: A10_Vukovich2002EmissProcess.pdf

A.11 Watson, T.B., et al. (2000). The Perfluorocarbon Tracer Releases during 

the Big Bend Regional Aerosol and Visibility Observational (BRAVO) 

Study. ...........................................................filename: A11_Watson2000Tracer.pdf 

Pitchford, M.L., et al. (2004). Big Bend Regional Aerosol and Visibility 

Observational Study Final Report. ............... filename: BRAVOFinalReport9-04.pdf
Final Report — September 2004 

xi

List of Figures 

Page

Figure 1-1 Big Bend National Park five-year composite contributions to haze by 

components. .............................................................................................................1-3

Figure 1-2 Quarterly aerosol contributions to light extinction averaged over five years 

(1998 – 2002). .........................................................................................................1-4

Figure 1-3 Examples of geographic distribution of the fraction of time that air parcels 

spend during the five days prior to arriving at Big Bend National Park for the 

months of January, May, July and September based upon a five-year analysis 

period (1998 to 2002). .............................................................................................1-6 

Figure 1-4 Monthly fractions of time that air parcels spend in a region prior to arrival at 

Big Bend, based on five-day back trajectory calculations for the five-year 

period from 1998 to 2002. .......................................................................................1-6 

Figure 1-5 (Left) SO2 emissions based on the 1999 BRAVO emissions inventory used in 

the REMSAD and CMAQ-MADRID modeling. ....................................................1-8 

Figure 1-6 Contributions to haze by components during the BRAVO Study period. 

(LAC is light absorbing carbon.)...............................................................................1-9 

Figure 1-7 Estimates by several data analysis and modeling methods of the study-period 

averaged percent contributions to particulate sulfate at Big Bend by U.S. and 

Mexico sources. .....................................................................................................1-12 

Figure 1-8 Smoothed daily estimates by source regions to particulate sulfate 

concentration (top plot) and fraction of total predicted particulate sulfate 

(bottom plot) at Big Bend during the study period. ...............................................1-13 

Figure 1-9 Estimated contributions to light extinction by various particulate sulfate 

source regions. .......................................................................................................1-15 

Figure 1-10 Estimated contributions by particulate sulfate source regions to Big Bend 

light extinction levels for the 1/5 haziest days and the 1/5 least hazy days of 

the BRAVO Study period. ........................................................................................15 

Figure 1-11 Fraction of time that air parcels spent during five-day trajectories for periods 

with the 20% highest concentrations of particulate sulfate compounds and for 

the periods with the 20% lowest concentrations of particulate sulfate 

compounds during the BRAVO Study period July through October 1999. ..........1-17 

Figure 2-1 Location map of Big Bend National Park in southwestern Texas. ..........................2-1 

Figure 2-2 Texas and Mexico (above) and the terrain surrounding Big Bend National 

Park in western Texas and northern Mexico (below). .............................................2-2 

Figure 2-3 Map showing monitoring sites for preliminary visibility study. .............................2-4 

Figure 2-4 Big Bend National Park five-year composite contributions to haze by 

components. .............................................................................................................2-5 

Figure 2-5 Big Bend extinction budget time plots of individual years. ....................................2-6 
Final Report — September 2004 

xii

List of Figures (continued)

Page

Figure 3-1 Data recovery of 24-hr tracer sample data during the two periods when 24-hr 

tracer sampling took place. ......................................................................................3-7 

Figure 3-2 Network of 24-hour gas and aerosol sampling locations. .......................................3-9 

Figure 3-3 Network of 6-hour gas and aerosol sampling locations. .........................................3-9 

Figure 3-4 Upper-air meteorological sites. .............................................................................3-12 

Figure 4-1 The BRAVO Study emission inventory was compiled for the shaded areas of 

the U.S. and Mexico shown here. ............................................................................4-2 

Figure 4-2 Locations of offshore platforms included in the BRAVO Study emissions 

inventory. .................................................................................................................4-4 

Figure 4-3 SO2 emissions rates from the BRAVO Study emissions inventory are shown 

as proportional to the bar heights on the map. .........................................................4-4 

Figure 4-4 (Left) SO2 emissions based on the 1999 BRAVO emissions inventory used in 

the REMSAD and CMAQ-MADRID modeling. ....................................................4-9 

Figure 5-1 Groups of BRAVO sampling sites that showed similar particulate matter 

behavior. ..................................................................................................................5-2 

Figure 5-2 Sulfate and SO2 time series at K-Bar. .....................................................................5-2 

Figure 5-3 Composition of PM2.5 aerosol throughout Texas during the August 29-

September 4, 1999, sulfate episode at Big Bend. ....................................................5-3 

Figure 5-4 Timelines of the PM2.5 molar ratio of NH4

+

/SO4

2– and aerosol acidity at Big 

Bend National Park. ................................................................................................5-8 

Figure 5-5 Example of hourly fine sulfate and sulfur dioxide concentration 

measurements at Big Bend National Park. ..............................................................5-9 

Figure 5-6 Example of light scattering coefficient measured at ambient humidity for 

particles below 2.5 μm, compared with measured hourly-averaged sulfate 

concentration, accumulation mode volume and light scattering coefficient, 

and coarse mode particle scattering, all derived from physical size 

distribution measurements. ....................................................................................5-10 

Figure 5-7 The n-alkane carbon preference index (CPI) for the BRAVO organic aerosol 

sample composites. ................................................................................................5-11 

Figure 5-8 Timelines of dry particulate matter volume concentrations (in μm3

/cm3) at 

Big Bend National Park for the accumulation and coarse modes, as computed 

from measured size distributions. ..........................................................................5-13 

Figure 5-9 Timeline of very fine (0.26 μm > Dp > 0.09 μm) silicon (x 25) and sulfur 

concentrations at Big Bend National Park during August 1999. ...........................5-14 
Final Report — September 2004 

xiii

List of Figures (continued)

Page

Figure 5-10 Comparisons of 12-hour averages of the photoacoustic light absorption 

measurements and the aethalometer black carbon measurements (top) and 

IMPROVE EC measurements (bottom) during the BRAVO Study. .....................5-17 

Figure 5-11 Comparison of hourly averaged black carbon and light absorption 

measurements during the BRAVO study time period of Figure 5-10. ..................5-18 

Figure 5-12 Average distribution of the measured components of extinction at Big Bend 

during the BRAVO Study period ............................................................................5-21 

Figure 5-13 Frequencies of wind directions at three height ranges during July-October 

1999, as measured by the BRAVO radar wind profilers. ......................................5-22 

Figure 5-14 July 1999 monthly resultant winds at 850 mb (approximately1500 m MSL), 

showing flow from the south in the Big Bend area. ..............................................5-23 

Figure 5-15 Surface weather map for 6 am CST on August 20, 1999. .....................................5-24 

Figure 5-16 Surface weather map for 6 am CST on August 29, 1999. .....................................5-24 

Figure 5-17 Surface weather map for 6 pm CST on September 11, 1999. ...............................5-25 

Figure 5-18 Surface weather map for 6 pm CST on September 13, 1999. ...............................5-26 

Figure 5-19 Time series of influence functions at 6-hr sampling sites for the Eagle Pass 

continuous tracer, ocPDCH. ..................................................................................5-28 

Figure 5-20 Time series of influence functions at 6-hr sampling sites for the Northeast 

Texas tracer, i-PPCH. ............................................................................................5-28 

Figure 5-21 Time series of influence functions at 6-hr sampling sites for the San Antonio 

tracer, PDCB. ........................................................................................................5-29 

Figure 5-22 Time series of influence functions at 6-hr sampling sites for the Houston 

tracer, PTCH. .........................................................................................................5-29 

Figure 5-23 Alternate day tracer PDCB versus continuous tracer ocPDCH influence 

functions at 6 hour sites for periods of timing tracer release (7/5/99- 9/13/99). 

.................................................................................................................................5-30 

Figure 5-24 Daytime only (8 am to 8 pm CDT) tracer PTCH versus continuous tracer 

ocPDCH influence functions at 6 hour sites for periods of timing tracer 

release (7/5/99- 9/13/99). ......................................................................................5-31 

Figure 5-25 Normalized ratio of PDCB to ocPDCH released from Eagle Pass at four 

monitoring sites. ....................................................................................................5-32 

Figure 5-26 Distribution of estimated transport times of Eagle Pass tracers to 6-hour 

monitoring sites in each 6-hour period during the timing tracer study (7/5/99- 

9/13/99). ................................................................................................................5-33
Final Report — September 2004 

xiv

List of Figures (continued)

Page

Figure 6-1 Comparison of sulfate and ammonium measurements by UC Davis and 

Colorado State University. ......................................................................................6-1 

Figure 6-2 Molar ratio of ammonium to sulfate as measured by UC Davis and Colorado 

State University during the BRAVO Study period. ................................................6-2 

Figure 6-3 Nitrate concentrations at K-Bar as measured by UC Davis and Colorado 

State University during the BRAVO Study Period. ................................................6-3 

Figure 6-4 Calculated contributions to haze by components of the aerosol during the 

BRAVO Study period. ............................................................................................6-8 

Figure 6-5 Comparison of extinction measured by the BIBE1 transmissometer and 

calculated from PM species concentrations. .........................................................6-10 

Figure 6-6 Comparison of extinction measured by the BBEP transmissometer (with 

additional lamp brightening adjustments) with that calculated from PM 

species concentrations. ..........................................................................................6-13 

Figure 7-1 Comparison of wind roses for July 1995-1998 (left) and 1999 (right). ..................7-2 

Figure 7-2 Comparison of wind roses for August 1995-1998 (left) and 1999 (right). ..............7-3 

Figure 7-3 Comparison of wind roses for September 1995-1998 (left) and 1999 (right). ........7-3 

Figure 7-4 Comparison of wind roses for October 1995-1998 (left) and 1999 (right). ............7-4 

Figure 7-5 Residence times for July-October 1999 (left) and the five-year July-October 

average (right), for 10 and 1,500 meter back-trajectory starting heights at Big 

Bend. .......................................................................................................................7-6 

Figure 7-6 Differences in residence times between July-October 1999 and the five-year 

(1998-2002) July-October average for all three back trajectory starting 

elevations. ................................................................................................................7-7 

Figure 7-7 Differences in residence times between July-October 1998, 2000, 2001, and 

2002 and the five-year (1998-2002) July-October average for the 500m 

starting elevation. ....................................................................................................7-8 

Figure 7-8 Big Bend extinction budget time plots of individual years. ..................................7-10 

Figure 7-9 Big Bend National Park five-year composite contributions to haze by 

components. ...........................................................................................................7-11 

Figure 7-10 Means and standard deviations of concentrations of components of PM10 at 

Big Bend National Park during four different averaging periods. ........................7-12 

Figure 7-11 Means and standard deviations of particle-caused light extinction estimated 

from concentrations of components of PM10 at Big Bend National Park 

during four different averaging periods. ................................................................7-14 
Final Report — September 2004 

xv

List of Figures (continued)

Page

Figure 7-12 Estimated relative contributions of various particulate matter components to 

particle-caused light extinction during four different averaging periods. .............7-15 

Figure 7-13 Box plots of measured fine mass concentration frequency distributions 

during four different averaging periods. ................................................................7-15 

Figure 7-14 Box plots of measured coarse mass concentration frequency distributions 

during four different averaging periods. ................................................................7-16 

Figure 7-15 Box plots of ammonium sulfate concentration frequency distributions during 

four different averaging periods. ...........................................................................7-17 

Figure 7-16 Box plots of particle chemical extinction frequency distributions during four 

different averaging periods. ...................................................................................7-18 

Figure 8-1 Locations of the triply-nested MM5 domains, with grid resolutions of 36, 12, 

and 4 km. .................................................................................................................8-7

Figure 8-2 Source areas with map identification numbers used for Trajectory Mass 

Balance Modeling. ................................................................................................8-11 

Figure 8-3 Locations of 17 source areas composed of 100-km grid virtual sources used 

to track transport and dispersion in the Forward Mass Balance Regression 

method. ..................................................................................................................8-13

Figure 8-4 Map of the REMSAD attribution source regions. .................................................8-19 

Figure 8-5 The CMAQ-MADRID attribution source regions. ...............................................8-20 

Figure 8-6 Plumes of a conservative tracer, released from four sites within Texas, as 

simulated by the REMSAD air quality model (4 October 1999). .........................8-21 

Figure 8-7 Comparison of spatial patterns of observed sulfate (left) and simulated 

sulfate (right) (19 August 1999). ...........................................................................8-22 

Figure 8-8 Precipitating clouds (yellow), non-precipitating clouds (blue), wind vectors, 

and streamlines predicted by the MM5 weather model (1 October 1999). ...........8-22 

Figure 9-1 Comparisons of MM5 and EDAS wind direction frequencies versus radar 

wind profiler measurements, by level above ground, for July-September 1999 

at Big Bend National Park. ......................................................................................9-8 

Figure 9-2 Comparisons of MM5 and EDAS wind direction frequencies versus radar 

wind profiler measurements, by level above ground, for July-September 1999 

at Llano, Texas. .....................................................................................................9-10 

Figure 9-3 Examples of REMSAD precipitation prediction and observed precipitation 

maps (for July 2, 1999). .........................................................................................9-11 

Figure 9-4 Examples of REMSAD predicted cloud cover and corresponding GOES 

satellite picture (for July 3, 1999). ........................................................................9-12 
Final Report — September 2004 

xvi

List of Figures (continued)

Page

Figure 9-5 Examples of the effects of EDAS and MM5 wind fields on back trajectories 

produced by the CAPITA Monte Carlo model. .....................................................9-15 

Figure 9-6 Examples of the effect of start height on the trajectories produced by the 

HYSPLIT model with the EDAS wind field. ........................................................9-16 

Figure 9-7 The tracer release regions (shaded boxes) defined for the TrMB evaluation. .......9-18 

Figure 9-8 Comparison of observed and modeled tracer concentrations, for the Eagle 

Pass, San Antonio, and Houston tracers, at Big Bend National Park over the 

duration of the study. .............................................................................................9-22 

Figure 9-9 Comparison of spatially-averaged observed and modeled tracer 

concentrations in southwest Texas (in the same format as Figure 9-8). ................9-23 

Figure 9-10 FMBR reconstructions of the Eagle Pass and northeast Texas tracer release 

locations and rates. ................................................................................................9-26 

Figure 9-11 Average percentage source contributions to measured tracer at Big Bend, as 

estimated by FMBR (red) and as measured (blue). ...............................................9-28 

Figure 9-12 Scatter plots of REMSAD sulfate concentration attributions vs. number of 

endpoints for each of four large source areas using 5-day back trajectories 

from the CAPITA MC Model and MM5 winds. ...................................................9-31 

Figure 9-13 Example of the REMSAD-simulated dispersion of the four tracer plumes on 

28 September 1999. ...............................................................................................9-35 

Figure 9-14 Comparison of 24-hr three-site average REMSAD predictions (red) of the 

spatially-averaged concentrations in Big Bend National Park versus three-site 

average measurements (blue) for the continuous Eagle Pass tracer. .....................9-36 

Figure 9-15 Comparison of 24-hr three-site average REMSAD predictions (red) of the 

spatially-averaged concentrations in Big Bend National Park versus three-site 

average measurements (blue) for the northeast Texas tracer. ...............................9-37 

Figure 9-16 Comparison of 24-hr three-site average REMSAD predictions (red) of the 

spatially-averaged concentrations in Big Bend National Park versus three-site 

average measurements (blue) for the San Antonio tracer. .....................................9-37 

Figure 9-17 Comparison of 24-hr three-site average REMSAD predictions (red) of the 

spatially-averaged concentrations in Big Bend National Park versus three-site 

average measurements (blue) for the Houston tracer. ...........................................9-38 

Figure 9-18 Comparisons of observed (blue) and modeled (red) time series of 24-hr 

averaged concentrations of SO2, sulfate, and total sulfur at the K-Bar 

sampling site in Big Bend National Park. .............................................................9-39 

Figure 9-19 Smoothed REMSAD simulation of ground-level sulfate concentrations at 

1700 CDT on 28 September 1999. ........................................................................9-43 
Final Report — September 2004 

xvii

List of Figures (continued)

Page

Figure 9-20 Scatter plots of REMSAD 24-hr sulfur concentration predictions versus 

measured values at 37 BRAVO network locations over the full BRAVO 

Study period. .........................................................................................................9-45 

Figure 9-21 Measured (top) and CMAQ-simulated (bottom) time series of NE Texas 

tracer concentrations (in ppq) at K-Bar. ................................................................9-46 

Figure 9-22 Measured (top) and CMAQ-simulated (bottom) time series of Eagle Pass 

PDCH tracer concentrations (in ppq) at K-Bar. ....................................................9-47 

Figure 9-23 Measured (top) and CMAQ-simulated (bottom) time series of Houston tracer 

concentrations (in ppq) at K-Bar. ..........................................................................9-47 

Figure 9-24 Measured (top) and CMAQ-simulated (bottom) time series of San Antonio 

tracer concentrations (in ppq) at K-Bar. ................................................................9-48 

Figure 9-25 Spatial distributions of mean normalized bias and mean normalized error in 

CMAQ-MADRID predictions of fine sulfate over the BRAVO network. ............9-55 

Figure 9-26 Measured and simulated 24-hr SO2 (top) and sulfate (bottom) concentrations 

at K-Bar. ................................................................................................................9-58

Figure 9-27 Measured and simulated daily SO2 concentrations (top) and fine sulfate 

concentrations (bottom) at Big Thicket. ................................................................9-59 

Figure 9-28 Compositions of observed and simulated PM2.5 at K-Bar, averaged over the 

duration of the BRAVO Study. .............................................................................9-62 

Figure 10-1 Contour plot of locations of top 50 loadings scores for Factor 1 (Soils). ..............10-4 

Figure 10-2 Contour plot of locations of top 50 loadings scores for Factor 2 (Coal 

Burning). ...............................................................................................................10-4 

Figure 10-3 Contour plot of locations of top 50 loadings for Factor 3 (Undetermined 

source type). ..........................................................................................................10-5 

Figure 10-4 Contour plot of locations of top 50 loadings for Factor 4 (Smelting). ..................10-5 

Figure 10-5 Distribution of mean particulate sulfur concentrations over the portion of the 

study period when all sites had sufficiently complete data for EOF analysis. ......10-8 

Figure 10-6 Composite of mean sulfur concentrations (ng/m3

) measured during 

September and October in 1996 (the preliminary study) and 1999 (the 

BRAVO Study). ....................................................................................................10-9 

Figure 10-7 The four EOF analysis-derived spatial factors for particulate sulfur and their 

temporal weights during most of the BRAVO Study period. ..............................10-10 

Figure 10-8 Air mass transport patterns to Big Bend during three particulate sulfur 

episodes. ..............................................................................................................10-12 
Final Report — September 2004 

xviii

List of Figures (continued)

Page

Figure 10-9 Residence time probability distributions showing transport pathways during 

high particulate sulfur days, based on the EDAS/FNL wind fields. .....................10-13 

Figure 10-10 Residence time probability distributions showing transport pathways during 

high particulate sulfur days, based on the BRAVO 36km MM5 wind fields. ....10-14 

Figure 10-11 Residence time probability distributions showing transport pathways during 

low particulate sulfur days, based on the EDAS/FNL wind fields. .....................10-15 

Figure 11-1 Map of the REMSAD modeling domain and the four principal geographic 

regions to which sulfate at Big Bend National Park (red diamond) was 

attributed. ...............................................................................................................11-2 

Figure 11-2 REMSAD simulation of sulfate concentrations on 17 August 1999 at 1500 

UTC using the full BRAVO emissions inventory. ................................................11-3 

Figure 11-3 REMSAD simulation of sulfate concentrations from emissions in the Eastern 

U.S. source region on 17 August 1999 at 1500 UTC. ...........................................11-4 

Figure 11-4 REMSAD simulation of sulfate concentrations from emissions in the 

Mexican source region on 17 August 1999 at 1500 UTC. ....................................11-4 

Figure 11-5 REMSAD simulation of sulfate concentrations from emissions in Texas on 

17 August 1999 at 1500 UTC. ...............................................................................11-5 

Figure 11-6 REMSAD simulation of sulfate concentrations from emissions in the 

Western U.S. source region on 17 August 1999 at 1500 UTC. .............................11-5 

Figure 11-7 REMSAD simulation of sulfate concentrations attributable to sulfur 

concentrations defined along the modeling domain boundaries by the 

GOCART global model on 17 August 1999 at 1500 UTC. ..................................11-6 

Figure 11-8 Observed and REMSAD-estimated sulfate concentrations at Big Bend and 

REMSAD-estimated contributions by source region (using the “emissions 

out” approach) for (a) the 4-month BRAVO Study period and (b-e) July 

through October, respectively. ..............................................................................11-7 

Figure 11-9 REMSAD-estimated relative attributions, of average sulfate concentrations at 

Big Bend for each source region (using the “emissions out” approach) for (a) 

the 4-month BRAVO Study period and (b-e) the months of July through 

October, respectively. ............................................................................................11-8 

Figure 11-10 Daily REMSAD attributions of sulfate concentrations at Big Bend to the four 

source regions and the GOCART boundary concentrations, based on the 

“emissions out” approach. .....................................................................................11-9 

Figure 11-11 Source regions used for CMAQ-MADRID sulfate attributions. No source 

attribution simulations were conducted for the open water Gulf of Mexico 

(red) region. .........................................................................................................11-12 
Final Report — September 2004 

xix

List of Figures (continued)

Page

Figure 11-12 CMAQ-MADRID average attribution of fine sulfate at K-Bar over the 

4-month BRAVO Study period, expressed as ratios of estimated average 

regionally-attributed concentrations of sulfate to average total estimated 

sulfate. .................................................................................................................11-13 

Figure 11-13 Daily CMAQ-MADRID attributions of sulfate concentrations (in μg/m3

) at 

Big Bend to the four source regions and the boundary concentrations. ..............11-15 

Figure 11-14 Study-period source attributions of fine sulfate (in μg/m3

) at K-Bar by the 

synthesized and original models. .........................................................................11-19 

Figure 11-15 Synthesized REMSAD estimates of K-Bar sulfate source attributions for 

seven selected episodes. ......................................................................................11-20 

Figure 11-16 Synthesized CMAQ-MADRID estimates of K-Bar sulfate source attributions 

for seven selected episodes. .................................................................................11-21 

Figure 11-17 Smoothed daily Synthesized CMAQ-MADRID attributions of sulfate at KBar. ......................................................................................................................11-22 

Figure 12-1 Simulated surface layer PTCH tracer concentrations (released from Houston 

TX) for October 12th 1999 generated by REMSAD at 36km and 12km and by 

CMAQ at 12km. ....................................................................................................12-4 

Figure 12-2 Smoothed daily BRAVO Estimates of contributions to Big Bend particulate 

sulfate by source region. ......................................................................................12-12 

Figure 12-3 Estimated contributions to light extinction by various particulate sulfate 

source regions. .....................................................................................................12-13 

Figure 12-4 BRAVO Estimates of contributions by particulate sulfate source regions to 

Big Bend light extinction levels for the 1/5 haziest days and the 1/5 least 

hazy days of the BRAVO Study period. .............................................................12-14 

Figure 12-5 Big Bend National Park five-year composite contributions to haze by 

components. .........................................................................................................12-15 

Figure 12-6 Big Bend extinction budget time plots for individual years. ...............................12-16 

Figure 12-7 Monthly fractions of time that air parcels spend in a region prior to arrival at 

Big Bend in 1998 to 2002 are shown as solid bars, based on five-day back 

trajectory calculations. .........................................................................................12-17 

Figure 12-8 Percent of time that air parcels en route to Big Bend spent over various 

locations during five-day trajectories for periods with the 20% highest 

concentrations of particulate sulfate compounds at Big Bend (left) and for the 

periods with the 20% lowest concentrations of particulate sulfate compounds 

at Big Bend (right) during the BRAVO Study period of July through October 

1999. ....................................................................................................................12-19 
Final Report — September 2004 

xx

List of Tables 

Page

Table 3-1 Tracer release schedule first phase of study. ...........................................................3-4 

Table 3-2 Tracer release schedule for the second half of the study. ........................................3-4 

Table 3-3 PFT data uncertainty (RMS error) in parts per quadrillion and correlation 

coefficients for collocated measurements. ..............................................................3-6 

Table 3-4 Number of measurement sites by measurement type. .............................................3-8 

Table 3-5 Aerosol and tracer monitoring site abbreviations, names, latitude, longitude, 

elevation, and purpose. ..........................................................................................3-10 

Table 3-6 Specialized aerosol and gaseous measurements at Big Bend. ...............................3-11 

Table 3-7 Upper-air meteorological monitoring site locations and types. .............................3-13 

Table 4-1 BRAVO Study emissions inventory data sources. ..................................................4-2 

Table 4-2 Point source emissions data for Mexico. .................................................................4-3 

Table 4-3 Surrogate types for the BRAVO modeling domains. ..............................................4-5 

Table 5-1 Summary of fine mass component concentrations (in μg/m3

) at Big Bend 

National Park. ..........................................................................................................5-5 

Table 5-2 Summary of coarse mass concentrations (in μg/m3

) at Big Bend National 

Park. .........................................................................................................................5-6 

Table 5-3 Summary of measurements of particle absorption and scattering (in Mm-1) at 

Big Bend National Park. ........................................................................................5-20 

Table 5-4 Summary of tracer data at the 6-hour sampling sites. Shown are the 

percentage of observations with concentrations greater than 2 times 

analytical uncertainty, the 90th percentile influence function (χ/Q) in 10-11

s/m3

, and the distance of the monitoring site from the tracer release location. .....5-27 

Table 6-1 Mass extinction efficiencies derived by Mie theory for PM measured at Big 

Bend National Park. ................................................................................................6-6 

Table 6-2 Summary of extinction measurements and calculations. ........................................6-7 

Table 6-3 Summary of factor analysis results (Varimax rotation) for Big Bend PM2.5 

data. .......................................................................................................................6-11 

Table 6-4 Multiple regression fits of factor scores and CM to BIBE1 transmissometer 

daily average bext. ..................................................................................................6-12 

Table 6-5 Summary of results from regressing measured extinction (Mm-1) against 

extinction calculated using the IMPROVE equation. ............................................6-13 

Table 6-6 Multiple regression fits of factor scores and CM to BBEP daily average bext. ......6-14 
Final Report — September 2004 

xxi

List of Tables (continued)

Page

Table 7-1 Monthly average temperature, RH, and f(RH) at Big Bend for hours with RH 

< 90%. .....................................................................................................................7-1 

Table 8-1 Summary of ensemble air mass history analysis methods. .....................................8-9 

Table 8-2 Names and map identification numbers for individual source areas composite 

source regions. .......................................................................................................8-12 

Table 8-3 Annual SO2 emissions (units of million metric tons per year) from the 

BRAVO emissions inventory for area and point sources within the four 

attribution source regions of the REMSAD model domain (see Figure 8-4). .......8-19 

Table 9-1 Ad hoc benchmarks of surface-layer meteorological model accuracy for airquality applications (from Emery et al., 2001). .......................................................9-3 

Table 9-2 Performance metrics for the 12-km and 36-km grid MM5 simulations over 

the area of the 12-km modeling domain. .................................................................9-4 

Table 9-3 Comparison of modeled winds to radar wind profiler measurements for JulySeptember 1999. ......................................................................................................9-6 

Table 9-4 Comparison of modeled winds to radar wind profiler measurements in 

October 1999. ..........................................................................................................9-7 

Table 9-5 Example of the qualitative ratings of predicted and observed precipitation for 

the five regions, for the maps shown in Figure 9-3. ..............................................9-12 

Table 9-6 Results of TrMB attribution of the tracer material that arrived at K-Bar from 

9/17 to 10/28/99. ...................................................................................................9-19 

Table 9-7 Model performance statistics for the Monte Carlo simulation of tracer 

concentrations averaged over the Big Bend sites (San Vicente, K-bar and 

Persimmon Gap) and over all six-hour tracer sites (San Vicente, K-bar, 

Persimmon Gap, Marathon, Fort Stockton and Monahans Sandhills) for the 

entire 4-month study period. .................................................................................9-24 

Table 9-8 Performance of the FMBR method in estimating tracer release rates. ..................9-27 

Table 9-9 Percent attributions of REMSAD-simulated sulfate by TrMB using MM5 

winds and various trajectory models, compared to the corresponding 

REMSAD attributions in the two bottom rows show. ...........................................9-29 

Table 9-10 Source attribution estimates from application of the FMBR method using a 

set of REMSAD-predicted sulfate concentrations, and comparison with a 

sample set of REMSAD source attributions. .........................................................9-33 

Table 9-11 REMSAD model performance statistics for the four tracers. ................................9-38 

Table 9-12 Performance statistics over the full BRAVO Study period for REMSAD 

simulations of SO2, sulfate, and total sulfur at the three sampling locations 

within Big Bend National Park. ............................................................................9-40 
Final Report — September 2004 

xxii

List of Tables (continued)

Page

Table 9-14 Intersite correlations of 24-hr average concentrations of SO2, sulfate, and 

total sulfur measured at the three Big Bend National Park monitoring sites. ........9-42 

Table 9-15 Consolidated performance statistics over the full BRAVO Study period for 

REMSAD simulations of SO2, sulfate, and total sulfur at 37 BRAVO 

network measurement locations. ...........................................................................9-44 

Table 9-16 Performance of CMAQ at simulating tracer concentrations at K-Bar for all 

tracers released during the study. ..........................................................................9-49 

Table 9-17 Network-average CMAQ-MADRID SO2 and fine SO4

2– performance 

statistics for preliminary and final base case simulations. .....................................9-52 

Table 9-18 CMAQ-MADRID performance for 24-hr averages of particulate matter 

components at K-Bar over the duration of the BRAVO study. .............................9-53 

Table 9-19 CMAQ-MADRID performance for 24-hr averages of particulate matter 

components over all BRAVO sites over the duration of the BRAVO study. ........9-54 

Table 9-20 CMAQ-MADRID performance for sulfur species at the K-Bar site, BBNP, 

over the duration of the BRAVO study. ................................................................9-57 

Table 9-21 CMAQ-MADRID performance for sulfur species at the Big Thicket site over 

the duration of the BRAVO study. ........................................................................9-57 

Table 9-22 CMAQ-MADRID performance for 24-hr concentrations at the K-Bar site 

over the duration of the BRAVO study. ................................................................9-61 

Table 9-23 Comparison of sulfate simulation performance of the synthesized REMSAD 

and CMAQ models at Big Bend over the period 9 July through 28 October 

1999. ......................................................................................................................9-65 

Table 10-1 Average study-period TAGIT attributions of particulate sulfur, SO2, and total 

sulfur (± the standard errors of the means) to local source emissions. ..................10-2 

Table 10-2 Components with the most significant factor loadings for each factor of the 

regional data set. ....................................................................................................10-3 

Table 10-3 Components with the most significant factor loadings for each factor of the 

Big Bend data set. ..................................................................................................10-6 

Table 10-4 Relative attributions of median 24-hour particulate sulfur at Big Bend to each 

major source region by TrMB using various trajectory model/wind field 

combinations. ......................................................................................................10-16 

Table 10-5 FMBR attribution results and performance statistics using MM5 and 

EDAS/FNL 10-day transport trajectories. ...........................................................10-19 

Table 11-1 REMSAD source attributions of fine sulfate at the K-Bar site during seven 

selected episodes. ................................................................................................11-11 
Final Report — September 2004 

xxiii

List of Tables (continued)

Page

Table 11-2 CMAQ-MADRID estimates of average source region contributions to sulfate 

concentrations (in μg/m3

) at K-Bar during each of the BRAVO Study period 

months and during the entire study. ....................................................................11-13 

Table 11-3 Source region attributions of fine sulfate at K-Bar as estimated by CMAQMADRID for each month of the study period. ....................................................11-14 

Table 11-4 CMAQ source attributions of fine sulfate at the K-Bar site during seven 

selected episodes. ................................................................................................11-16 

Table 11-5 Source region attributions of fine sulfate at K-Bar as estimated by CMAQMADRID for the 20 days with the greatest relative underestimates and the 20 

days with the greatest relative overestimates. .....................................................11-17 

Table 11-6 Relative study-period source attributions (in %) of fine sulfate at K-Bar by 

the synthesized and original models. ...................................................................11-18 

Table 12-1 Estimates of Big Bend’s relative sulfate source attributions (in percent) by 

the various air quality and receptor modeling techniques. ....................................12-6 

Table 12-2 Estimates of Big Bend’s relative sulfate source attributions (in percent) by 

the refined approaches. ........................................................................................12-10 
Final Report — September 2004 

xxiv

List of Abbreviations and Acronyms 

ACARS ............................Aircraft Communications Addressing and Reporting System 

AGL .................................above ground level 

AIM..................................Aerosol Inorganics Model 

AP ....................................accumulation potential 

ARL..................................NOAA Air Resource Laboratory 

ATAD ..............................NOAA ARL’s Atmospheric Transport and Dispersion model 

babs....................................coefficient of optical absorption 

(a measure of light absorption) 

BBNP ...............................Big Bend National Park 

BC ....................................black carbon 

BEIS.................................Biogenic Emissions Inventory System 

BELD ...............................Biogenic Emissions Landcover Database 

bext ....................................coefficient of optical extinction (a measure of light extinction) 

BNL..................................Brookhaven National Laboratory 

bsp .....................................coefficient of optical scattering 

(a measure of light scattering by particles) 

CAPITA ...........................Center for Air Pollution Impact and Trend Analysis 

(Washington University, St. Louis, MO) 

CASTNET........................USEPA Clean Air Status and Trends Network 

CEM.................................continuous emissions monitors 

CENEPRED.....................Centro Nacional de Prevención de Desastres 

(Mexico’s National Center for Disaster Prevention) 

CJ .....................................Ciudad Juarez 

CM ...................................coarse-particle mass 

CMAQ..............................Models-3/Community Multiscale Air Quality model (simulates 

various chemical and physical processes that are thought to be 

important for understanding atmospheric trace gas transformations 

and distributions over urban and regional scales) 

CMB.................................Chemical Mass Balance (a receptor model) 

CMC.................................CAPITA Monte Carlo 

COSPEC ..........................correlation spectrometer 

CPI ...................................carbon preference index 
Final Report — September 2004 

xxv

List of Abbreviations and Acronyms (continued)

CSU..................................Colorado State University 

D.......................................normalized directional frequency 

EC ....................................elemental carbon 

EDAS ...............................Eta Data Assimilation System 

(collects data for input to the Eta weather forecast model) 

EDGAR............................Emission Database for Global Atmospheric Research 

EI......................................emissions inventory 

EOF..................................Empirical Orthogonal Function 

EPS...................................Emissions Preprocessor System 

ERG..................................Eastern Research Group 

f(RH) ................................relative humidity adjustment factor (adjusts the light scattering 

effect of sulfates and nitrates to account for particle growth caused 

by water vapor in the atmosphere) 

FA ....................................factor analysis 

fL......................................femtoliter 

FMBR ..............................Forward Mass Balance Regression 

GC/MS .............................gas chromatography with mass spectrometry 

GDAS...............................Global Data Assimilation System 

GEIA................................Global Emissions Inventory Activity 

GOCART .........................Global Ozone Chemistry Aerosol Radiation Transport global 

climate model 

GOES ...............................NOAA Geostationary Operational Environmental Satellites system 

HCP..................................high conditional probability 

HIP ...................................high incremental probability 

HRT..................................high condition residence time (residence time for transport during 

high concentration or haze level conditions, typically the top 10% 

to 20% of conditions) 

HSC..................................high condition source contribution 

HYSPLIT .........................Hybrid Single-Particle Lagrangian Integrated Trajectory model 

IF......................................influence function 

IMPROVE........................Interagency Monitoring of Protected Visual Environments 
Final Report — September 2004 

xxvi

List of Abbreviations and Acronyms (continued)

INE...................................Instituto Nacional de Ecología 

(Mexico’s National Institute of Ecology) 

INEGI...............................Instituto Nacional de Estadística Geografía e Informática 

IPCC.................................Intergovernmental Panel on Climate Change 

i-PPCH .............................perfluoro-iso-propylcyclo-hexane 

(a perfluorocarbon used as an artificial tracer) 

LAC..................................light-absorbing carbon 

LCP ..................................low conditional probability 

LIP....................................low incremental probability 

LRT..................................low condition residence time (residence time for transport during 

low concentration or haze level conditions, typically the lowest 

10% to 20% of conditions) 

LSC ..................................low condition source contribution 

MADRID .........................Model for Aerosol Dynamics, Reaction, Ionization, and 

Dissolution (simulates atmospheric particulate matter) 

MAE.................................mean absolute error 

MCIP................................Meteorology Chemistry Interface Processor, MeteorologyChemistry Interface Processor 

MDL.................................minimum detection limit 

Mm–1 ................................inverse megameter (1/1,000,000 meter; a light extinction 

measurement unit) 

MM5 ................................Pennsylvania State University/National Center for Atmospheric 

Research mesoscale model (a limited-area, nonhydrostatic, terrainfollowing sigma-coordinate model designed to simulate or predict 

mesoscale atmospheric circulation) 

MMS ................................Minerals Management Service 

MOAD .............................Outer Continental Activity Database 

MOHAVE........................Measurement of Haze and Visibility Effects 

MOUDI............................Micro-Orifice Uniform Deposit Impactor 

(a cascade impactor that collects size-fractionated aerosol particle 

samples for gravimetric and chemical analysis) 

MRF .................................Medium Range Forecast model 

N MX NEI........................Mexico’s national emissions inventory 

NCEP ...............................National Centers for Environmental Prediction 
Final Report — September 2004 

xxvii

List of Abbreviations and Acronyms (continued)

NEI...................................National Emissions Inventory 

ng......................................nanogram 

NGO.................................non-governmental organization 

NO....................................nitrogen oxide 

NOAA..............................National Oceanic and Atmospheric Administration 

NOX..................................oxides of nitrogen 

NOY..................................sum of NOX + HNO3 + HONO + PAN 

NPS ..................................National Park Service (part of the U.S. Department of the Interior) 

OC....................................organic carbon 

OCM ................................organic carbon mass concentration 

OLS..................................ordinary least squares 

OMC ................................organic carbon compounds 

oPDCH.............................perfluoro-1,2-dimethylcyclohexane 

(a perfluorocarbon used as an artificial tracer) 

ocPDCH ...........................an isomer of oPDCH accounting for 45% 

(a perfluorocarbon used as an artificial tracer) 

ORT..................................overall residence time 

OSC..................................overall source contribution 

PAVE ...............................Package for Analysis and Visualization for Environmental data 

(a software application to visualize multivariate gridded 

environmental datasets) 

PDCB ...............................1,1,2,2,3,4-hexafluoro-3,4-bis(trifluoro-methyl) cyclobutane 

(a perfluorocarbon used as an artificial tracer) 

PDF ..................................probability density function 

pg......................................picogram (10–12 g) 

PM10 .................................particulate matter with aerodynamic diameters smaller than 10 μm 

PM2.5 ................................particulate matter with aerodynamic diameters smaller than 2.5 μm 

ppq....................................parts per quadrillion 

PROFEPA........................La Procuraduría Federal de Protección al Ambiente 

(Mexico’s Program of Environmental Justice Procuration) 

PTCH ...............................perfluoro-1,3,5-trimethylcyclohexane 

(a perfluorocarbon used as an artificial tracer) 
Final Report — September 2004 

xxviii

List of Abbreviations and Acronyms (continued)

r or R ................................correlation coefficient 

r

2

 or R2..............................correlation coefficient squared, also coefficient of determination 

RADM..............................Regional Acid Deposition Model 

RASS................................radio acoustic sounding system 

READY............................NOAA ARL’s Real-Time Environmental Applications and Display 

System 

REMSAD.........................Regional Modeling System for Aerosols and Deposition 

RH....................................relative humidity 

RMSE...............................root mean square error 

RT ....................................residence time 

RWP.................................radar wind profiler 

SC.....................................source contribution 

SEM .................................scanning electron microscopy 

SEMARNAT....................Secretaría de Medio Ambiente y Recursos Naturales 

(Mexico’s Ministry of the Environment) 

SMOKE............................Sparse Matrix Operator Kernel Emissions model 

SO2 ...................................sulfur dioxide 

SO4 or SO4

=

 or SO4

2– .......sulfate 

SSI....................................Spectral Statistical Interpolation 

TAGIT..............................Tracer-Aerosol Gradient Interpretive Technique (uses tracer data 

from a monitoring network to distinguish sites impacted by a 

source tagged with artificial tracer from nonimpacted sites) 

TCEQ ...............................Texas Commission on Environmental Quality 

(formerly Texas Natural Resource Conservation Commission) 

TJ......................................Tijuana 

TOR..................................thermal/optical reflectance 

TrMB................................Tracer Mass Balance 

TS.....................................total sulfur (contributed by both SO2 and SO4

=

) 

UCD .................................University of California at Davis 

URG .................................University Research Glassware 

USEPA.............................U.S. Environmental Protection Agency 
Final Report — September 2004 

xxix

List of Abbreviations and Acronyms (continued)

UTC..................................Coordinated Universal Time (the international time standard; UTC 

is the current term for what was commonly referred to as 

Greenwich Meridian Time [GMT]; zero [0] hours UTC is midnight 

in Greenwich, England) 

VIF ...................................variance inflation factor (indicates the collinearity of a source area 

with all other source areas in TrMB analysis) 

Vis5d................................an OpenGL-based volumetric visualization program for scientific 

datasets in 3+ dimensions 

WRAP..............................Western Regional Air Partnership 

σz ......................................standard deviation of the vertical dispersion of a Gaussian plume 

for stable conditions