1. An Overview of the Big Bend Regional Aerosol and Visibility Observational (BRAVO) Study Marc Pitchford, Ph.D National Oceanic and Atmospheric Administration Mark Green, Ph.D. Desert Research Institute

2. Reasons for the Study Clean Air Act provides protection from visibility impacts at certain national parks and wilderness areas including Big Bend Popular perception in the region that haze levels have been increasing at Big Bend Concerns that increased emissions along the US/Mexico border are responsible for haze increases Preliminary Big Bend Haze Study called for a source attribution study

3. Photos

4. BRAVO Study Participants U.S.Activities EPASponsor, project management & direction NPSSponsor, project management & modeling TNRCCSponsor, project coordination, aircraft monitoring, data analysis EPRISponsor, met. and air quality modeling NOAATechnical management, tracer release, upper air met. & data analysis DRITechnical management, database, data analysis, emissions inventory, and emissions characterization BNLTracer sample analysis UCDAerosol monitoring and analysis, tracer sampling CIRAAerosol monitoring size and composition special studies at Big Bend ARSContinuous optical & met. monitoring, photos, special study support ENSRIndependent quality assurance auditors MexicoActivities PROFEPA Project management & direction [involvement discontinued during planning phase]

5. Seasonality and components of haze Aerosol light extinction: Sulfate41% Organic Carbon19% Black Carbon21% Crustal16% Nitrate 4%

6. Transport patterns – late July, late September Transport PatternsTransport Patterns

7. SO 2 emissions

8. Distance weighted SO 2 emissions

9. Frequency weighted SO 2 emissions

10. Seasonality of transport to Big Bend

11. Summary of Field Study 4 month study from July-October Tracer release near Carbon I/II (Eagle Pass- 3 tracers) and Big Brown first half Tracer release from Eagle Pass, San Antonio, W.A. Parish, Big Brown 2 nd half Large particulate and tracer monitoring network (but none in Mexico) Additional upper air measurements Visibility measurements at Big Bend “Special” studies at Big Bend Aircraft measurements

12. BRAVO particulate, SO 2, and tracer monitoring network

13. Tracer Release Equipment

14. Big Bend Specialized Measurements MeasurementsAveraging Period High time resolution, high sensitivity SO 2 1-hour High time resolution particulate sulfate12-minutes High time resolution perfluorocarbon tracer1-hour PM 2.5 carbonaceous aerosol24-hour Carbon speciation (GC/MS) for selected periods24-hour Gaseous nitric acid24-hour Gaseous ammonia24-hour Gaseous hydroperoxides1-hour MOUDI size-resolved aerosol ions24-hour DRUM size-resolved aerosol elements1-hour Various particle size monitors – DMA, OPC, etc.Minutes Various optical measurements – nephelometers, transmissometers, aetholometers, etc Minutes Scanning electron microscopy - selected samples24-hour

15. Data Recovery Particulate sampling network –Complete deployment delayed ~3 weeks for new samplers –Otherwise expect high recovery Tracer sampling network –Extended period in middle of study with only 6 tracer sampling sites due to delayed analysis capability –Most extensive tracer study ever done, even considering periods with only a few sites High data recovery for other monitoring (visibility, meteorology, air quality)

16. Status of Data from Field Study Tracer release data Surface and upper air (Radar wind profiler) Light scattering (haze) 12-minute Sulfate, hourly SO 2 at Big Bend Photographs at Big Bend Limited Big Bend aerosol chemical analysis Status of Data from Field StudyStatus of Data from Field Study

17. Status of Data from Field Study Light extinction data – December, 2000 Complete chemical analysis of particulate data – November, 2000 Tracer data – January, 2001 Source profiles – November, 2000 Emissions – February, 2001 Status of Data from Field StudyStatus of Data from Field Study

18. Hourly Extinction Coefficient

19. Hourly SO 2 & Sulfate

20. Hourly Total & Sulfate Extinction Coefficient

21. Data Analysis Process Descriptive analysis – maps and time plots of variables, mean, standard deviation, etc. Association analysis – relationships among variable, e.g. correlations, closure Representativeness of study period Attribution analysis- source and receptor models, etc. Reconciliation of results Conceptual model

22. Attribution Analysis Multiple air quality simulation & receptor modeling methods used for attribution Tracer data divided into subset for “training” and a sequestered subset for “testing” to evaluate methods’ performance Study findings are developed by reconciling results of the various methods

23. BRAVO MM5 Met. Modeling Domains 36 km 12 km 4 km Cell Sizes

24. BRAVO Emissions Inventory Data Sources U.S.MexicoOff Shore PointNET & CEM (large sources) INE for 20 major cities MMS- MOAD3 AreaNET except Texas TNRCC in Texas INE for 20 major cities; scaled by population elsewhere N/A MobileNET except Texas TNRCC in Texas INE mobile emissions scaled by population TNRCC & MMS- MOAD3 BiogenicBEIS-2 with land- use data N/A FireAVHRR, GOES, & TOMS satellite imagery N/A

25. Estimated Schedule Always takes longer than planned Get all data into database – autumn 2000 Data analysis and modeling – end of 2001 Reconciliation of results – March 2002 Draft Report – May 2002 Final report July 2002