Empirical and Chemical Transport Modeling of Ozone’s Response to Emissions Controls

Presentation Abstract

Air pollution controls have led to dramatic improvements in air quality in California’s South Coast Air Basin (which includes Los Angeles). However, in spite of those controls, Los Angeles continues to experience the highest levels of ground-level ozone in the US, and some of the high particulate matter levels as well. Typically, chemical transport models (CTMs) are used to assess how further controls will lead to improvements, and what level of controls are required to bring an area in to attainment with air quality standards. However, model predicted levels of improvement have not agreed with observed changes, both leading to periods of greater reductions being found, then, recently, peak ozone levels increasing. The region’s long record of observations, along with the changes in ozone and it’s precursors, allow construction of empirically-derived ozone-precursor relationships, which can both be used to help assess the observed response of ozone to estimated emissions and how CTM-derived responses compare to observed-responses. This is done by constructing ozone isopleths using both empirical methods and using direct sensitivity analysis of a CTM (in this case, CMAQ). While qualitatively similar, important differences are found between the empirical and CTM-derived isopleths, and the derived sensitivities. The empirical approach is used to develop responses of the basins ozone design value, individual site location and ozone exposure to emissions changes.

SPEAKER

Prof. Armistead (Ted) Russell

Howard T. Tellepsen Chair and Regents’ Professor, Georgia Institute of Technology

Prof. Armistead (Ted) Russell is the Howard T. Tellepsen Chair and Regents’ Professor of Civil and Environmental Engineering at the Georgia Institute of Technology, where his research is aimed at better understanding the dynamics of air pollutants at urban and regional scales and assessing their impacts on health and the environment to develop approaches to designing strategies to effectively improve air quality. He and his group have conducted air quality modeling, field experiments, and data analysis across scales, with a particular focus studies that will support improved air quality management. He earned his M.S. and Ph.D. degrees in Mechanical Engineering at the California Institute of Technology (Caltech), conducting his research at Caltech’s Environmental Quality Laboratory. His B.S. is from Washington State University. Dr. Russell was a member of the U.S. Environmental Protection Agency’s (EPA’s) Clean Air Science Advisory Committee (CASAC)