Surface and lightning sources of nitrogen oxides over the United States: Magnitudes, chemical evolution, and outflow

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Read Full Article (file size: 2098323 bytes) Cited by JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 112, D12S05, doi:10.1029/2006JD007912, 2007 Surface and lightning sources of nitrogen oxides over the United States: Magnitudes, chemical evolution, and outflow R. C. Hudman Department of Earth and Planetary Sciences and Division of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA D. J. Jacob Department of Earth and Planetary Sciences and Division of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA S. Turquety Department of Earth and Planetary Sciences and Division of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA E. M. Leibensperger Department of Earth and Planetary Sciences and Division of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA L. T. Murray Department of Earth and Planetary Sciences and Division of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA S. Wu Department of Earth and Planetary Sciences and Division of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA A. B. Gilliland Air Resources Laboratory, Atmospheric Sciences Modeling Division, NOAA, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA M. Avery Atmospheric Sciences Division, NASA Langley Research Center, Hampton, Virginia, USA T. H. Bertram College of Chemistry, University of California, Berkeley, California, USA W. Brune Department of Meteorology, Pennsylvania State University, University Park, Pennsylvania, USA R. C. Cohen College of Chemistry, University of California, Berkeley, California, USA J. E. Dibb Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, New Hampshire, USA F. M. Flocke Earth Observing Laboratory, National Center for Atmospheric Research, Boulder, Colorado, USA A. Fried Earth Observing Laboratory, National Center for Atmospheric Research, Boulder, Colorado, USA J. Holloway Cooperative Institute for Research In Environmental Science, University of Colorado, Boulder, Colorado, USA Earth System Research Laboratory, NOAA, Boulder, Colorado, USA J. A. Neuman Cooperative Institute for Research In Environmental Science, University of Colorado, Boulder, Colorado, USA Earth System Research Laboratory, NOAA, Boulder, Colorado, USA R. Orville Department of Atmospheric Science, Texas A&M University, College Station, Texas, USA A. Perring College of Chemistry, University of California, Berkeley, California, USA X. Ren Department of Meteorology, Pennsylvania State University, University Park, Pennsylvania, USA G. W. Sachse Atmospheric Sciences Division, NASA Langley Research Center, Hampton, Virginia, USA H. B. Singh NASA Ames Research Center, Moffett Field, California, USA A. Swanson Earth Observing Laboratory, National Center for Atmospheric Research, Boulder, Colorado, USA Cooperative Institute for Research In Environmental Science, University of Colorado, Boulder, Colorado, USA Earth System Research Laboratory, NOAA, Boulder, Colorado, USA P. J. Wooldridge College of Chemistry, University of California, Berkeley, California, USA Abstract We use observations from two aircraft during the ICARTT campaign over the eastern United States and North Atlantic during summer 2004, interpreted with a global 3-D model of tropospheric chemistry (GEOS-Chem) to test current understanding of regional sources, chemical evolution, and export of NO_x. The boundary layer NO_x data provide top-down verification of a 50% decrease in power plant and industry NO_x emissions over the eastern United States between 1999 and 2004. Observed NO_x concentrations at 8–12 km altitude were 0.55 ± 0.36 ppbv, much larger than in previous U.S. aircraft campaigns (ELCHEM, SUCCESS, SONEX) though consistent with data from the NOXAR program aboard commercial aircraft. We show that regional lightning is the dominant source of this upper tropospheric NO_x and increases upper tropospheric ozone by 10 ppbv. Simulating ICARTT upper tropospheric NO_x observations with GEOS-Chem requires a factor of 4 increase in modeled NO_x yield per flash (to 500 mol/flash). Observed OH concentrations were a factor of 2 lower than can be explained from current photochemical models, for reasons that are unclear. A NO_y-CO correlation analysis of the fraction f of North American NO_x emissions vented to the free troposphere as NO_y (sum of NO_x and its oxidation products) shows observed f = 16 ± 10% and modeled f = 14 ± 9%, consistent with previous studies. Export to the lower free troposphere is mostly HNO₃ but at higher altitudes is mostly PAN. The model successfully simulates NO_y export efficiency and speciation, supporting previous model estimates of a large U.S. anthropogenic contribution to global tropospheric ozone through PAN export. Received 11 August 2006; accepted 5 January 2007; published 18 April 2007. Keywords: reactive nitrogen; pollution; lightning. Index Terms: 0322 Atmospheric Composition and Structure: Constituent sources and sinks; 0345 Atmospheric Composition and Structure: Pollution: urban and regional (0305, 0478, 4251); 0368 Atmospheric Composition and Structure: Troposphere: constituent transport and chemistry; 3324 Atmospheric Processes: Lightning; 9350 Geographic Location: North America. Read Full Article (file size: 2098323 bytes) Cited by Citation: Hudman, R. C., et al. (2007), Surface and lightning sources of nitrogen oxides over the United States: Magnitudes, chemical evolution, and outflow, J. Geophys. Res., 112, D12S05, doi:10.1029/2006JD007912. Copyright 2007 by the American Geophysical Union.

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