EC-30. Reactive nitrogen and ozone spatial distributions in two Southwestern U.S. cities

Nitrogen oxides, NOx, and ozone, O3, play crucial roles in the Earth’s atmospheric composition, oxidative capacity, regional air quality and climate and are inexorably linked through their complex photochemistry. In urban environments, anthropogenic emissions of NOx (NO2 + NO) primarily come from fossil fuel burning. NO emissions are a secondary source of NO2 and the photolysis of NO2 ultimately provides the dominate source of tropospheric O3. Tropospheric O3 acts as a greenhouse gas and, along with NO2, exacerbates air pollution though chemical reactions that lead to the formation of urban haze, secondary organic aerosols, nitric acid, and longer lived peroxyacylnitrates species (PANs). The negative impacts of O3 and NO2 on vegetation, human health, and climate have led to a worldwide science initiative to monitor these species through a combination of satellite measurements, flight campaigns, and ground-based instruments. We have contributed to this initiative by taking ground-based measurements of NO2, NO, NOy, and O3 during the 2021 Summer SUNVEx campaign using two NOAA instruments: Nitrogen Oxides by Cavity Ring Down (NOxCaRD) and Nitric Oxide Laser Induced Fluorescence (NO-LIF). Data were collected in two Southwestern U.S. cities, Las Vegas, NV, and Los Angeles, CA, using both stationary and mobile platforms. Here, we use these data to assess current emission inventories, ascertain correlations between urban air pollution and human demographic parameters, and determine trends in air pollution over time through comparisons to previous campaign measurements.