Influence Of Transboundary Pollution On The Variability Of Surface Ozone Concentration In The Desert Southwest Of The U.S.: Case Study For Arizona
Presenter: Grace Betito P31
Co-Author(s): -
Advisor(s): Armin Sorooshian
1Hydrology & Atmospheric Sciences
Arizona, a rapidly growing state in the southwestern U.S., faces ozone pollution challenges, with several counties (including Yuma and Maricopa counties) classified as O3 nonattainment areas. Previous studies in the region have reported pollution transport from neighboring states impacting O3 levels. In this study, we use five-year (2017-2021) hourly back-trajectories and O3 concentration data for concentration-weighted trajectory (CWT) analysis to identify transport pathways and potential source regions of O3 at six monitoring sites representing both rural and urban areas within Arizona. We divide the data into five seasons (winter, spring, dry summer, monsoon summer , fall) to examine variations in O3 concentration and transport across sites and seasons. The highest mean O3 concentrations occur during spring (37-49 ppb), dry summer (39-51 ppb), and monsoon summer (34-49 ppb), while winter (19-41 ppb) exhibits the lowest seasonal mean. The CWT results reveal that high O3 concentrations (≥ 40 ppb) in Arizona, with the exception of Phoenix and Tucson sites, are influenced significantly by regional and international transport, especially in spring and dry summer. The major potential source areas (excluding the Phoenix and Tucson sites) are predominantly located outside Arizona. This study highlights the critical role of pollution transport in influencing O3 variability within Arizona and will be valuable in shaping pollution control strategies in the future.