Inventories of HR VOC Emissions and Impact of Emission Magnitude and Variability on Ozone Formation in the Houston/Galveston Area

David Allen and Tom Edgar
University of Texas, Austin

Harvey Jeffries, Mort Webster, and Mike Symons,
University of North Carolina, Chapel Hill

Sponsored by Texas Environmental Research Consortium &
Houston Advanced Research Center

Project Abstract

A series of air quality studies have demonstrated that emissions of ozone precursors in the Houston-Galveston area (HGA), particularly the emissions of highly reactive volatile organic compounds (HRVOCs), are greater in magnitude and exhibit greater temporal variability than previously recognized. The uncertainty and inherent variability in emissions of HRVOCs from industrial sources has caused the State of Texas to examine choices for reductions in emissions of nitrogen oxides and HRVOCs. There are a number of technical issues that must be resolved for the State to make these evaluations for HGA. This project was initiated to provide the State of Texas with assistance for some of these tasks, including:

Develop tools for evaluating and improving base case model performance

Draft a conceptual model for the use of aircraft and field study data in evaluating the performance of gridded photochemical models
Utilize data available from TexAQS in combination with virtual aircraft flown in results fields of TCEQ's air quality model simulations for August--September, 2000.
Apply model diagnostic tools (e.g., process analysis) that help ensure that model is generating the right results for the right reasons

Characterize emission events and routine point source emission variability

Draft a conceptual model for point source emission inventories, documenting methodologies for characterizing variability and observational evidence of point source emission variability
Develop air quality models capable of evaluating large numbers of emission snapshots
Using "bottom-up" point source emission variability models, develop probable emission snapshots
Compare range of snapshots to base case inventory imputed from observational evidence
Document variability in ozone formation that would be a consequence of point source emission variability
Demonstrate effective HRVOC reduction options that account for emissions variability

Conceptual Model for Emissions Inventories in HGA

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