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Recent Developments in California and the U.S. Bart Croes Air Resources Board Sacramento, California 6 March, 1996. Outline. Ambient Air Techniques Fuel-Based Inventories Tunnel/Roadway Studies Aloft Measurement Studies Remote Sensing Studies Recommendations. Ambient Air Techniques.
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Recent Developments in California and the U.S. Bart Croes Air Resources Board Sacramento, California 6 March, 1996
Outline • Ambient Air Techniques • Fuel-Based Inventories • Tunnel/Roadway Studies • Aloft Measurement Studies • Remote Sensing Studies • Recommendations
Ambient Air Techniques • Ratios • Source Reconciliation • semi-volatile PAHs • GRACE/SAFER • Derives source profiles • Requires large VOC dataset
GRACE/SAFER • Graphical Ratio Analysis for Composition Estimates • Define limits of species ratios • Source Apportionment by Factors with Explicit Restrictions • Multivariate receptor model • GRACE and nonnegative source compositions • Henry et al. (1994) • 1990 Atlanta Ozone Precursor Study • 62% tailpipe exhaust • 15% whole gasoline evaporation • 4% headspace vapor
Fuel-Based Inventories • Requirements • Fuel sales, relative fuel economies • CO/CO2 and HC/CO2 measurements • VOC/CO and NOx/CO correlations • Limitations • Stabilized exhaust only • Regional inventory only • Singer and Harley (1996) • CO agrees with MVEI 7G • 58% of CO from cars and trucks > 10 years
Tunnel/Roadway Studies • Caldecott Tunnel (San Francisco) • Effects of oxygenated gasoline • Effects of reformulated gasoline • PM10/PM2.5 Studies • University of California at Davis • University of California at Riverside • Highways not a PM source
Aloft Measurement Studies • Tower/Tethered Balloon • Walnut Grove television tower • single ozone analyzer • Teflon lines at 5 levels to 500 m • Manned Balloon • U.S. Air Force • 250 kg payload • ozone, NOx, VOC sampling • Aircraft • SCOS97-NARSTO • 4 aircraft • ozone, NOx, NOy, CO, VOC sampling
Remote Sensing Studies • Roadway • Remote Sensing Device • CO, “HC”, NOx • Area Source • University of California at Davis • Volume Source • Duke Forest, North Carolina • Texas petroleum refinery
Recommendations • Release tracer gas(es) • Measure CO and CO2 • Evaluate source profiles with GRACE/SAFER • Timing of emissions is a critical factor in ozone formation