Fresh Insights into the Sources and Distribution of Peroxyacetyl Nitrate (PAN) from New In Situ and Satellite Observations
Monday, 15 December 2014: 9:45 AM
PAN (peroxyacetyl nitrate, CH3C(O)OONO2) is only one of the organic nitrogen compounds produced when hydrocarbons are oxidized in the presence of nitrogen oxide radicals (NOx = NO + NO2), but it is the most important atmospheric NOx reservoir and a critical pathway by which NOx reaches the remote troposphere to impact oxidant distributions and remote nitrogen deposition. We present the analysis of new in situ and satellite observations to highlight previously unobserved features of regional-to-global PAN distributions. Our latest in situ data were collected as part of the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ), which took place in the Colorado Front Range during July and August 2014. This data set serves as a case study of PAN formation where significant oil and gas production intersects a major urban-suburban region. Preliminary data, analyzed in conjunction with concurrent observations of other trace species, show extremely elevated PAN and other organic nitrogen compounds in plumes with strong oil and gas source signatures. These plumes have been observed at both suburban and remote (Rocky Mountain National Park) measurement sites. In addition, new PAN retrievals from the Tropospheric Emission Spectrometer (TES), flying on the NASA Aura satellite, can provide a more global picture of PAN. We present TES retrievals of PAN from the Northern Hemisphere over the ten-year lifetime of the Aura mission. The TES PAN dataset offers unprecedented observations of the inter-annual variability of PAN, the transpacific transport of reactive nitrogen species, and the role of biomass burning in the generation of extreme PAN abundances.