An Overview of the Big Bend Regional Aerosol and Visibility Observational (BRAVO) Study

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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

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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

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Photos
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BRAVO Study Participants
U.S. Activities
EPA Sponsor, project management direction
NPS Sponsor, project management modeling
TNRCC Sponsor, project coordination, aircraft monitoring, data analysis
EPRI Sponsor, met. and air quality modeling
NOAA Technical management, tracer release, upper air met. data analysis
DRI Technical management, database, data analysis, emissions inventory, and emissions characterization
BNL Tracer sample analysis
UCD Aerosol monitoring and analysis, tracer sampling
CIRA Aerosol monitoring size and composition special studies at Big Bend
ARS Continuous optical met. monitoring, photos, special study support
ENSR Independent quality assurance auditors
Mexico Activities
PROFEPA Project management direction involvement discontinued during planning phase
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Seasonality and components of haze

• Aerosol light extinction
• Sulfate 41
• Organic Carbon 19
• Black Carbon 21
• Crustal 16
• Nitrate 4

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Transport Patterns
Transport patterns late July, late September
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SO2 emissions
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Distance weighted SO2 emissions
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Frequency weighted SO2 emissions
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Seasonality of transport to Big Bend
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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 2nd 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

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BRAVO particulate, SO2, and tracer monitoring
network
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Tracer Release Equipment
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Big Bend Specialized Measurements
Measurements Averaging Period
High time resolution, high sensitivity SO2 1-hour
High time resolution particulate sulfate 12-minutes
High time resolution perfluorocarbon tracer 1-hour
PM2.5 carbonaceous aerosol 24-hour
Carbon speciation (GC/MS) for selected periods 24-hour
Gaseous nitric acid 24-hour
Gaseous ammonia 24-hour
Gaseous hydroperoxides 1-hour
MOUDI size-resolved aerosol ions 24-hour
DRUM size-resolved aerosol elements 1-hour
Various particle size monitors DMA, OPC, etc. Minutes
Various optical measurements nephelometers, transmissometers, aetholometers, etc Minutes
Scanning electron microscopy - selected samples 24-hour
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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)

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Status of Data from Field Study
Status of Data from Field Study

• Tracer release data
• Surface and upper air (Radar wind profiler)
• Light scattering (haze)
• 12-minute Sulfate, hourly SO2 at Big Bend
• Photographs at Big Bend
• Limited Big Bend aerosol chemical analysis

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Status of Data from Field Study
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

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Hourly Extinction Coefficient
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Hourly SO2 Sulfate
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Hourly Total Sulfate Extinction Coefficient
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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

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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

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BRAVO MM5 Met. Modeling Domains
Cell Sizes
36 km
12 km
4 km
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BRAVO Emissions Inventory Data Sources
U.S. Mexico Off Shore
Point NET CEM (large sources) INE for 20 major cities MMS-MOAD3
Area NET except Texas TNRCC in Texas INE for 20 major cities scaled by population elsewhere N/A
Mobile NET except Texas TNRCC in Texas INE mobile emissions scaled by population TNRCC MMS-MOAD3
Biogenic BEIS-2 with land-use data BEIS-2 with land-use data N/A
Fire AVHRR, GOES, TOMS satellite imagery AVHRR, GOES, TOMS satellite imagery N/A
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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