Temporal and spatial allocations of ozone precursor emissions in the Nashville, Tennessee area.

The Environmental Protection Agency (EPA) has required Tennessee to revise its State Implementation Plan (SIP) to include a program to meet the National Ambient Air Quality Standard (NAAQS) for ozone because Nashville and Memphis metropolitan areas in Tennessee violated this standard during the period from 1986 to 1988. The Tennessee Department of Health and Environment (TDHE) Division of Air Pollution and the University of Tennessee's (UT) Civil Engineering Department undertook the task of compiling the requisite emission inventory which provided input for air quality modeling necessary in revising the SIP. In addition, UT will perform a modeling study of the air quality planning region using the Urban Airshed Model (UAM) to aid in determining ozone control strategies. The UAM requires inputs of emissions and meteorological data which are then dispersed into a grid system to simulate formation of ozone across a specified region. A conceptual representation of UAM's functions is presented in Figure 1. The basis of this thesis is to show how emission inventory results can be allocated both spatially and temporally to be used as model inputs for the Nashville air quality planning area. Although UAM is capable of modeling a three-dimensional grid to describe emissions aloft in several different mixing layers, this study will assume that all emissions occur within the first grid layer. Only emissions of non-methane organic hydrocarbons, referred to in this thesis as volatile organic compounds (VOCs), and emissions of nitrogen oxide compounds (NOx) will be considered because they are direct precursors of ozone formation. A discussion of the regulatory background, inventory compilation, and results will be followed by a development of methods used to allocate emissions to grid cells. Spatial and temporal allocation of emissions will be evaluated respectively.