Collaborative Research: Aerosols, Nitrogen Oxides, and Ozone at the Mt. Bachelor Observatory

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This project supports the continuation of atmospheric measurements at Mt. Bachelor Observatory (MBO) in Central Oregon. The MBO is a high elevation (2.8 km above sea level) observatory that has been utilized for atmospheric chemistry research for the past 15 years. This project will build on the extensive knowledge base of past observations from MBO to examine key controls on western U.S. air quality in the spring, when natural and international anthropogenic sources of O3 and aerosols dominate, and summer, when wildfire smoke is a major driver of regional air pollution. Continuous measurements will be made at MBO of O3, CO, CO2, aerosol mass, scattering and absorption coefficients and meteorology. Three specific hypotheses will be addressed in this research: (1) Daily variations in baseline O3 are driven by large scale dynamics and transport including the El Nino-Southern Oscillation, the Pacific Decadal Oscillation, and the changing climate. The variations in O3 that can be observed in data from both MBO and the TEMPO satellite and are important for downwind air quality in the western U.S. (2) Nitrogen oxide chemistry in biomass burning plumes is controlled by both initial emissions and chemical processing enroute. Production of nitrous acid from aerosol nitrates (organic and inorganic) is an important NOx recycling mechanism and a source of hydroxyl radical. (3) Aerosol properties depend on chemical composition and aging. Light absorption by brown carbon can be comparable or exceed absorption by black carbon and can be linked to specific chemical components or chromophores. Organic aerosol volatility decreases with aging and oxidation.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.