Analytical Chemistry Seminar: Benjamin Nault and Jason Schroder
Analytical & Environmental Chemistry Division and Atmospheric Chemistry Program Seminar
Jointly sponsored by the Department of Chemistry and Biochemistry, CIRES, and the Environmental Program
Chemistry in of the coldest places in the atmosphere: Impacts of updated NOx lifetime and fate on lightning NOx emission rates
by Benjamin A. Nault - Postdoctoral Researcher, Department of Chemistry and CIRES, University of Colorado Boulder
Nitrogen oxides (NOx≡ NO + NO2) produced from lightning are an important natural source of NOx. This is the most important NOx source for the middle and upper troposphere. Lightning produced NOx controls the chemical production of middle and upper tropospheric ozone, an important greenhouse gas, and the oxidative capacity of the troposphere. However, the uncertainty in the emissions rates range from 2 to 8 Tg nitrogen per year. Recent studies have provided evidence that the oxidation of NOx to pernitric acid and nitric acid is slower than currently assumed and that methyl peroxy nitrate is an important temporary sink of upper tropospheric lightning NOx. Also, the conversion of dinitrogen pentoxide to nitric acid may be slower than currently assumed. I investigate the impacts of this updated kinetics and chemistry on model and in-situ observations of lightning NOx production rates. I show that using these results, the uncertainty range decreases. Also, the emission rates for different regions of the world increase by as much as 33% with the updated upper tropospheric NOx lifetime and fate.
Insights into Submicron Aerosol Composition and Sources from the WINTER Aircraft Campaign over the Eastern US
by Jason Schroder - Postdoctoral Researcher, Department of Chemistry and CIRES, University of Colorado Boulder
The WINTER aircraft campaign was a recent field experiment to probe the sources and evolution of gas and aerosol pollutants in Northeast US urban and industrial plumes during the winter. A highly customized Aerodyne aerosol mass spectrometer was flown on the NCAR C-130 to characterize submicron aerosol composition and evolution. Work towards constraining wintertime secondary organic aerosol formation and evolution will be presented from a case study of urban outflow from NYC. Observations and results of wintertime aerosol nitrate, power plant plume acidity, as well as measurements made from an oxidation flow reactor, flown for the first time, will be discussed.