Kristie A. Boering, (Professor in the Departments of Chemistry and of Earth and Planetary Science, University of California at Berkeley)

While inverse modeling studies of atmospheric nitrous oxide (N₂O) concentrations have narrowed uncertainties in the magnitudes, geographic distribution, and timing of N₂O fluxes to the atmosphere that are needed to understand and to mitigate the rising concentration of this greenhouse gas and ozone depleting substance in the atmosphere, significant uncertainties remain, including accounting for the return of N₂O-depleted air from the stratosphere. Measurements of the average and site-specific nitrogen and the oxygen isotopic compositions of N₂O can provide an additional means to attribute observed N₂O variations to its various sources or stratospheric sink.  In this talk, I will highlight recent laboratory work determining the isotopic composition of N₂O produced in a corona discharge (a process that can produce N₂O in thunderstorms), showing it has an isotopic fingerprint that is distinct from that for soil and ocean emissions, for biomass burning, and for the return of air from the stratosphere. Although N₂O produced by lightning is only a tiny fraction of the global annual source of N₂O to the atmosphere, the large and unique isotopic signature of corona discharge N₂O now characterized completes the array needed to identify production that could be detectable, for example, in the outflow from storms in the upper troposphere. Isotope compositions of N₂O in a biomass burning plume in the tropical upper troposphere, from a Southern Ocean ship cruise, and from an Arctic peat circle ‘hot spot’ will also be compared and contrasted with the corona discharge results.

Kristie A. Boering is a professor in the Departments of Chemistry and of Earth and Planetary Science at UC Berkeley.  Specializing in physical and atmospheric chemistry, she and her research group investigate the influence of human activities on the atmosphere and climate through laboratory experiments and observations from high altitude aircraft and balloons. A graduate of UC San Diego (Chemistry with a Specialization in Earth Science, 1985) and Stanford (Physical Chemistry, 1991), she was elected to the National Academy of Sciences in 2018.