Exploring Regional Emissions and Tropospheric Ozone in the Eastern United States Using Air Quality Models and Data Products

Tropospheric ozone (O3) is a harmful pollutant regulated by the US Environmental Protection Agency (EPA) through the use of designated air quality standards. Within the United States, approximately 110 million people live within counties designated as in non-attainment of the O3 standard. In this work, analysis is performed to examine the influence of anthropogenic emissions on tropospheric O3 production within the framework of the CMAQ regulatory air quality model. Adjustments are recommended to improve emission representation from the largest (class 3) commercial marine vessels (c3 Marine). Model results with the implemented corrections show improved comparison to surface O3 observations from AQS sites. Characterization of the photochemical O3 production regime (VOC or NOx sensitive) is performed using the ratio of formaldehyde (HCHO) and nitrogen dioxide (NO2) tropospheric column observations from the satellite borne Ozone Monitoring Instrument (OMI), and whole air sampling canisters in the Long Island Sound (LIS) collected on May 17th and 18th, 2017. Evidence for the importance of anthropogenic VOCs in the New York City pollution plume and their role in tropospheric O3 production is presented. Aircraft O3 observations are used to evaluate model performance of the National Oceanic Atmospheric Administration (NOAA) National Air Quality Forecast Capability system CMAQ model for the O3 event in the LIS. Finally, a series of CMAQ simulations are performed to suggest the likely inventory sector (non-road mobile) most responsible for the significant O3 production downwind of coastal urban centers like New York and Chicago. Important air quality policy implications of these findings are discussed