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Temporal/Spatial Statistical Analyses of Truck Transportation and Ozone DynamicsOliver H. Gao Faculty advisor: Dr. Debbie A. Niemeier, Department of Civil and Environmental Engr. UC Davis: 

Temporal/Spatial Statistical Analyses of Truck Transportation and Ozone Dynamics Oliver H. Gao Faculty advisor: Dr. Debbie A. Niemeier, Department of Civil and Environmental Engr. UC Davis NOx Curves by Day Ozone Curves by Day Figure 2. Estimated Relative Day Effects on Day-to-Sunday Ratios of Daily LDV and HDT Volumes: Urban vs. Rural Study Objective: Ground level ozone is a secondary pollutant from photochemical reactions of VOCs and NOx. On-road transportation emissions are the single major contributor to ozone precursors (30% in the U.S., 40% in CA). This study uses modern statistical tools to examine the interrelationships between spatial/temporal patterns of ozone concentrations and transportation activities. Ozone Weekend Effect (OWE): Figure 1 (functional data analysis of daily ozone/NOx cycles) shows typical diurnal ozone and NOx curves measured at an urban monitoring site in LA. This illustrates what has been known as the OWE: elevated ozone in spite of significantly dropped precursor NOx on weekends (New York, Washington, DC and Baltimore, etc.) NOx-reduction hypothesis on OWE states that Weekend drops of heavy-duty truck (HDT) relative to light-duty vehicle (LDV) traffic coupled with VOC-limited ozone system contribute to the OWE. Conclusion: Figure 2 illustrates the comparisons of weekly patterns between HDT and LDV traffic from our statistical analysis of Weigh-In-Motion(WIM) traffic data. The results of this study support the NOx-reduction hypothesis on the OWE. Figure 1. Diurnal Ozone and NOx Curves