Publication Date
6-2002
Document Type
Technical Report
Organizational Units
College of Natural Science and Mathematics, Chemistry and Biochemistry
Keywords
Atmospheric chemistry, Emissions, Pollutants
Abstract
The University of Denver conducted the third year of a multi-year remote sensing study in the Los Angeles, CA area. The remote sensor used in this study is capable of measuring the ratios of CO, HC, and NO to CO2 in motor vehicle exhaust. From these ratios, we calculate the percent concentrations of CO, CO2, HC and NO in motor vehicle exhaust which would be observed by a tailpipe probe, corrected for water and any excess oxygen not involved in combustion. The system used in this study was also configured to determine the speed and acceleration of the vehicle, and was accompanied by a video system to record the license plate of the vehicle. Eight days of fieldwork between June 6 and 13, 2001, were conducted on the uphill exit ramp from 91N to 60W in Riverside, CA. A database was compiled containing 19,800 records for which the State of California provided make and model year information. All of these records contained valid measurements for at least CO and CO2, 19,761 contained measurements for HC and 19,783 for NO data. The database, along with earlier databases and reports, can be found at www.feat.biochem.du.edu. The mean emissions for CO, HC, and NO were determined to be 0.39%, 100 ppm, and 400 ppm, respectively, with an average model year of 1994.5. The mean emissions in gm/kg of fuel consumed for CO, HC and NO were 48.3, 2.0 and 5.6. The fleet emissions measured in this study exhibit a gamma distribution, with the dirtiest 10% of the fleet responsible for 74%, 66%, and 52% of the CO, HC, and NO emissions, respectively. The majority of measurements (66%) at this location were of vehicles measured once. The remaining 34% of the measurements were of vehicles measured at least twice. By removing all of the repeat measurements from the database and allowing each vehicle to appear only once, we have shown that these repeat measurements are not skewing the results and that the full database is statistically representative of the actual fleet at the measurement site. Using vehicle specific power, it was possible to adjust the emissions of the vehicle fleet measured in 2001 to match the vehicle driving patterns of the fleet measured in 1999. The adjustment did not significantly alter the 2001 measurements because of the similarity in VSP profiles between 1999 and 2001. A model year adjustment was applied to a fleet of specific model year vehicles to track deterioration. Only NO emissions displayed fleet deterioration with this adjustment. Tracking of individual model years during the three years of measurements showed little deterioration in terms of CO for the most recent model years. In fact, model year was a greater determinant of CO emissions than age. An analysis of high emitting vehicles showed that there is considerable overlap of CO and HC high emitters. Finally, an analysis of measurement uncertainty indicated minimal noise in all three pollutants.
Copyright Statement / License for Reuse
Copyright Date
6-1-2002
Rights Holder
Sajal S. Pokharel, Gary A. Bishop, Donald H. Stedman
Provenance
Received from author
File Format
application/pdf
Language
English (eng)
Extent
30 pgs
File Size
191 KB
Publication Statement
Copyright is held by the author. User is responsible for all copyright compliance.
This research was supported by the nonprofit Coordinating Research Council, Inc. (CRC). The final results of the research conducted by, or under the auspices of, CRC are available to the public.
Recommended Citation
Pokharel, S. S., Bishop, G. A., & Stedman, D. H. (2002). On-road remote sensing of automobile emissions in the Los Angeles area: Year 3 (Riverside). Atlanta, GA: Coordinating Research Council.