Quantification of Uncertainty in Air Quality Models Used for Analysis of Ozone Control Strategies

EPA Grant Number: R824792
Title: Quantification of Uncertainty in Air Quality Models Used for Analysis of Ozone Control Strategies
Institution: University of Colorado at Boulder , University of California - Berkeley
EPA Project Officer: Chung, Serena
Project Period: October 1, 1995 through September 30, 1998 (Extended to September 30, 1999)
Project Amount: $426,233
RFA: Air Pollutants (1995) Recipients Lists
Research Category: Air Quality and Air Toxics , Air


Uncertainties in models used to predict the air quality impacts of prospective control measures have been cited as one reason why many urban areas have not been able to attain the National Ambient Air Quality Standard for ozone. This project is to demonstrate the use of systematic methods for uncertainty quantification and identification of influential sources of uncertainty. This will be accomplished by conducting a quantitative uncertainty analysis of the California/Carnegie Institute of Technology (CIT) trajectory model, applied for simulation conditions in the Los Angeles area on August 27-28, 1987. Uncertainties in emissions, chemical parameters and meteorological conditions are being studied. As a preliminary stage of the analysis, first-order sensitivity and uncertainty calculations are used to identify the influential parameters and inputs in the model. A global uncertainty analysis will then be conducted using Monte Carlo simulations with Latin hypercube sampling (LHS). A key component of the project is the development of new approaches for estimating uncertainties in critical model parameters and inputs. This includes exploring the use of an alternative motor vehicle emissions inventory for the Los Angeles area. The alternative inventory is based on gasoline sales data, infrared remote sensing measurements of CO, and observed ambient air concentration ratios of hydrocarbons to CO and nitrogen oxides to CO. In addition to examining how modeling uncertainties affect base case concentrations, their effect on predictions of relative concentration changes due to proposed control measures is also being studied. The results of this study will help decision makers gauge the reliability of predictions of benefits of control measures, and help set priorities for further research to improve modeling capabilities.

Publications and Presentations:

Publications have been submitted on this project: View all 6 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 2 journal articles for this project

Supplemental Keywords:

air, ambient air, atmosphere, ozone, particulates, oxidants, modeling, central, Colorado, CO, Region 8, RFA, Scientific Discipline, Air, particulate matter, Air Quality, mobile sources, Environmental Monitoring, tropospheric ozone, Atmospheric Sciences, Ecological Risk Assessment, Ecology and Ecosystems, ambient air quality, particulates, ozone occurrence, air quality models, ambient air, ambient measurement methods, ozone, National Ambient Air Quality Standard, Los Angeles, control measure modeling, modeling studies, atmospheric chemistry

Progress and Final Reports:

  • 1996
  • 1997
  • 1998
  • Final Report