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Grantee Research Project Results

Grantee Research Project Results

Modeling Regional Scale Ozone Sensitivity to Precursor Emissions with a Fuel-Based Motor Vehicle Emission Inventory

EPA Grant Number: U915548
Title: Modeling Regional Scale Ozone Sensitivity to Precursor Emissions with a Fuel-Based Motor Vehicle Emission Inventory
Investigators: Marr, Linsey C.
Institution: University of California - Berkeley
EPA Project Officer: Jones, Brandon
Project Period: May 1, 1999 through May 1, 2002
Project Amount: $73,958
RFA: STAR Graduate Fellowships (1999)
Research Category: Academic Fellowships , Engineering and Environmental Chemistry , Fellowship - Civil/Environmental Engineering



The objectives of this research project are to: (1) develop an improved understanding of regional scale ozone sensitivity to volatile organic compounds (VOCs) and nitrogen oxide (NOx) emissions; and (2) identify patterns in ozone time series observations that can be used to diagnose regional scale transport and VOC versus NOx sensitivity.


An Eulerian photochemical airshed model will be used to gain insight into ozone formation on a regional scale in central California. Meteorological data and pollutant concentrations, which are used as input to the model, will be obtained from a large field study in the San Joaquin Valley. To evaluate ozone sensitivity to precursor emissions, it is crucial that the emission inventory be accurate. Official estimates of motor vehicle emissions, the main anthropogenic source of VOC and NOx emissions in most populated areas, have been shown to be inaccurate, so the first step of this research will be to improve estimates of motor vehicle emissions. The revised motor vehicle emission inventory takes into account fuel consumption data, fuel-based emission factors from tunnel studies of on-road vehicles, and traffic count data specific to the day of week, hour of day, and vehicle class. The model will be used to examine the causes of patterns in ozone observations, such as a shift in the time of ozone peak at downwind sites, differing shapes of diurnal ozone profiles, and weekday versus weekend differences in ozone. These patterns may be indicators of regional scale transport and VOC versus NOx sensitivity.

Expected Results:

As a result of improved estimates of motor vehicle emissions, model performance will improve, with higher predicted ozone in urban areas - which suggests that these areas are VOC-sensitive.

Supplemental Keywords:

ozone, regional transport, motor vehicle emissions., RFA, Scientific Discipline, Air, Geographic Area, Ecosystem Protection/Environmental Exposure & Risk, Environmental Chemistry, State, Analytical Chemistry, mobile sources, Regional/Scaling, Environmental Engineering, Nox, modeling regional scale ozone, motor vehicle emissions, ecosystem scale, air quality models, ozone, VOCs, automotive emissions, air pollution, automobiles, emissions, airshed model, regional scale ozone sensitivity, emissions inventory, regional transport, California (CA)

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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