Date of Award


Semester of Degree


Document Type

Open Access Thesis

Degree Name

M.S. in Chemistry



Major Professor

Dr. Huiting Mao

Steering Committee Member

Dr. John Hassett

Steering Committee Member

Dr. Charles Kroll


In the troposphere, surface ozone is an air pollutant that has deleterious effects on human respiratory function and crop yields. Therefore, an understanding of spatial and temporal ozone concentration changes is necessary. The Ensemble Empirical Mode Decomposition (EEMD) method was used to analyze processes on varying time scales for surface ozone data from 25 U.S. National Park Service sites. Time scales of interest include the seasonal cycle, large-scale climate oscillations, and long-term (>10 years) trends. Variability in each of these oscillatory components is determined. Further analysis was done at one site after initial analyses yielded findings disparate from the rest of the study pool. For this site (DENA-HQ) variability in the El Niño Southern Oscillation and Pacific Decadal Oscillation was shown to affect the trajectory of pollutants to the site.The findings from this study can assist predictions regarding the timing and amplitude of peak ozone across the US and inform policy makers where emission reductions have been effective, enlightening future policy decisions.