Atmospheric Chemistry Program Seminar: Xiaomeng Jin

Space-based observations of ozone-NO_x-VOC-aerosol chemistry in urban and fire plumes

Prof. Xiaomeng Jin, 
Department of Environmental Sciences 
Rutgers University

Ground-level ozone (O₃) is one of six criteria air pollutants identified by U.S. Environmental Protection Agency (EPA), which is associated with increased risk of cardiovascular and respiratory diseases. More than 100 million US people live in O₃ non-attainment areas. In this talk, I will discuss how we use satellite remote sensing observations to understand the influence of anthropogenic and wildfire emissions on the formation of ground-level O₃. O₃ production is non-linearly dependent on the availability of its precursors: nitrogen oxides (NO_x) and volatile organic compounds (VOCs). Using long-term observations from the sun synchronous satellite instruments, we examine the multidecadal trends in O₃ chemistry, while the newly launched NASA’s geostationary TEMPO instrument is used to diagnose the diurnal variations of O₃ chemistry. Next, I will discuss the impacts of wildfires on O₃ and its precursors. Satellite observations reveal that wildfires cause widespread increase of O₃ precursors, which favor the O₃ production, but the smoke aerosols can inhibit O₃ production both radiatively and chemically. By accounting for the aerosol effects, we redefine the O₃ production regimes. We find widespread aerosol-inhibited conditions within wildfire plumes as well as in heavily polluted urban regions of Asia and Africa, where high aerosol loadings inhibit O₃ formation. Overall, our findings highlight how space-based observations can complement in-situ measurements and model simulations by providing information on the spatial and temporal variations of O3 chemistry.