Investigation of the Parameters Influencing Baseline Ozone in the Western United States: A Statistical Modeling Approach

Ground-level ozone (O-3) is a key atmospheric gas that controls the oxidizing capacity of the atmosphere and has significant health and environmental implications. Due to ongoing reductions in the concentrations of O-3 precursors, it is important to assess the variables influencing baseline O-3 to inform pollution control strategies. This study uses a statistical model to characterize daily peak 8 h O-3 concentrations at the Mount Bachelor Observatory (MBO), a rural mountaintop research station in central Oregon, from 2006-2020. The model was constrained by seven predictive variables: year, day-of-year, relative humidity (RH), aerosol scattering, carbon monoxide (CO), water vapor (WV) mixing ratio, and tropopause pressure. RH, aerosol scattering, CO, and WV mixing ratio were measured at MBO, and tropopause pressure was measured via satellite. For the full 15-year period, the model represents 61% of the variance in daily peak 8 h O-3, and all predictive variables have a statistically significant (p < 0.05) impact on daily peak 8 h O-3 concentrations. Our results show that daily peak 8 h O-3 concentrations at MBO are well-predicted by the model, thereby providing insight into what affects baseline O-3 levels at a rural site on the west coast of North America.

Automated summary

This study uses a statistical model to characterize daily peak 8-hour O-3 concentrations at a rural mountaintop research station in central Oregon. The results show that relative humidity, aerosol scattering, carbon monoxide, and water vapor mixing ratio significantly impact O-3 concentrations.