Mobile Observations of Ozone and Aerosols in Alabama: Southeastern US Summer Pollution and Coastal Variability

Abstract

AbstractWe present a detailed analysis of measurements of ozone (O3) and aerosols collected using multiple platforms and instruments during a 5‐day mini‐campaign in Alabama, for improving our understanding of the chemistry and air quality in the Southeastern United States. Our study features the first on‐road O3 lidar profiling on highways and the coordinated airborne observations that captured O3 and aerosol structures associated with synoptic weather conditions, stratospheric intrusions, wildfire smoke transport, and enhancements in urban areas. The Doppler wind lidar data suggest that the vertical structures and variability of O3 and aerosols at Dauphin Island, a coastal site in the Gulf of Mexico, were related to both the synoptic flow and local‐scale land‐sea breeze circulation. The onshore gulf breeze, which typically started in the afternoon, helped to quickly dilute air pollutants near the surface, resulting in large gradients toward inland areas. In contrast, gradients were much smaller on days without a gulf breeze. O3 and humidity were highly anti‐correlated in the lower free troposphere, but weakly anti‐correlated in the planetary boundary layer (PBL) suggesting more complicated emissions and sink of O3 in the PBL. Our on‐road and airborne measurement strategies to quantify the vertical and horizontal chemical gradients will be useful for future geostationary satellite validation.