Evaluation of the Spatial and Temporal Variations in Tropospheric Ozone Production Using Air Quality Models and Multiplatform Observations to Improve Ozone Control Strategies

Determining ways to reduce surface ozone, based on the interpretation of observations and air quality model output, is of keen interest to policy makers. Regulatory control strategies must be optimized to maximize the benefit to populations while minimizing costs to society. The lack of continuous, detailed in-situ observations of ozone precursors, such as NO_x and volatile organic compounds (VOCs), limits our ability to precisely identify the geographical regions, altitudes, and timing of ozone production over large areas of the United States. Anthropogenic VOC sources are often given secondary importance in regions that are considered to be dominated by VOCs from the terrestrial biosphere. However, this is an oversight because in regions of the atmosphere that are decoupled from the surface terrestrial biosphere, such as in the tropospheric residual layer, or over large bodies of water, the transport of anthropogenic VOCs can significantly impact local ozone production. We will use output from both the Community Multiscale Air Quality (CMAQ) and Comprehensive Air Quality Model with Extensions (CAMx) models as well as aircraft and satellite observations to help determine the non-linear nature of ozone production at high spatial scales with particular emphasis on the impact that point sources may have downwind. We will present recent work that highlights the diurnal variation and vertical dependence of ozone production regime not detected by currently available satellite platforms. Our model simulations indicate surface ozone in mid-Atlantic coastal regions and parts of the Great Lakes is primarily controlled by anthropogenic VOCs, attributed to inventory sectors that are commonly considered by air quality policy to be minor sources. The goal of this work is to provide a better description of surface ozone photochemistry in the models that are used to guide air quality regulation.