Modeling Regional Scale Ozone Sensitivity to Precursor Emissions with a Fuel-Based Motor Vehicle Emission InventoryEPA 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: Packard, Benjamin H
Project Period: May 1, 1999 through May 1, 2002
Project Amount: $73,958
RFA: STAR Graduate Fellowships (1999) RFA Text | Recipients Lists
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.
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.