Articles | Volume 14, issue 5
Atmos. Chem. Phys., 14, 2679–2698, 2014
Atmos. Chem. Phys., 14, 2679–2698, 2014

Research article 14 Mar 2014

Research article | 14 Mar 2014

Atmospheric peroxyacetyl nitrate (PAN): a global budget and source attribution

E. V. Fischer1, D. J. Jacob2, R. M. Yantosca2, M. P. Sulprizio2, D. B. Millet3, J. Mao4, F. Paulot1, H. B. Singh5, A. Roiger6, L. Ries7, R.W. Talbot8, K. Dzepina9, and S. Pandey Deolal10 E. V. Fischer et al.
  • 1Department of Atmospheric Science, Colorado State University, Fort Collins, CO, USA
  • 2School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
  • 3Department of Soil, Water and Climate, University of Minnesota, St. Paul, MN, USA
  • 4Princeton University, GFDL, Princeton, NJ, USA
  • 5NASA Ames Research Center, Moffett Field, CA, USA
  • 6Institut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Oberpfaffenhofen, Germany
  • 7Department of Earth and Atmospheric Sciences, University of Houston, Houston, TX, USA
  • 8Federal Environment Agency, GAW Global Station Zugspitze/Hohenpeissenberg, Zugspitze, Germany
  • 9Department of Chemistry, Michigan Technological University, Houghton, MI, USA
  • 10Bluesign Technologies AG, St. Gallen, Switzerland

Abstract. Peroxyacetyl nitrate (PAN) formed in the atmospheric oxidation of non-methane volatile organic compounds (NMVOCs) is the principal tropospheric reservoir for nitrogen oxide radicals (NOx = NO + NO2). PAN enables the transport and release of NOx to the remote troposphere with major implications for the global distributions of ozone and OH, the main tropospheric oxidants. Simulation of PAN is a challenge for global models because of the dependence of PAN on vertical transport as well as complex and uncertain NMVOC sources and chemistry. Here we use an improved representation of NMVOCs in a global 3-D chemical transport model (GEOS-Chem) and show that it can simulate PAN observations from aircraft campaigns worldwide. The immediate carbonyl precursors for PAN formation include acetaldehyde (44% of the global source), methylglyoxal (30%), acetone (7%), and a suite of other isoprene and terpene oxidation products (19%). A diversity of NMVOC emissions is responsible for PAN formation globally including isoprene (37%) and alkanes (14%). Anthropogenic sources are dominant in the extratropical Northern Hemisphere outside the growing season. Open fires appear to play little role except at high northern latitudes in spring, although results are very sensitive to plume chemistry and plume rise. Lightning NOx is the dominant contributor to the observed PAN maximum in the free troposphere over the South Atlantic.

Final-revised paper