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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
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Volume 13, issue 9
Atmos. Chem. Phys., 13, 4617–4630, 2013
© Author(s) 2013. This work is distributed under
the Creative Commons Attribution 3.0 License.
Atmos. Chem. Phys., 13, 4617–4630, 2013
© Author(s) 2013. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 06 May 2013

Research article | 06 May 2013

On the export of reactive nitrogen from Asia: NOx partitioning and effects on ozone

T. H. Bertram1,*, A. E. Perring1,**, P. J. Wooldridge1, J. Dibb3, M. A. Avery4, and R. C. Cohen1,2 T. H. Bertram et al.
  • 1Department of Chemistry, University of California, Berkeley, USA
  • 2Department of Earth and Planetary Science, University of California, Berkeley, USA
  • 3Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, USA
  • 4NASA Langley Research Center, Hampton, VA, USA
  • *now at: Department of Chemistry and Biochemistry, University of California, San Diego, USA
  • **now at: NOAA Earth System Research Laboratory, Boulder, CO, USA

Abstract. The partitioning of reactive nitrogen (NOy was measured over the remote North Pacific during spring 2006. Aircraft observations of NO, NO2, total peroxy nitrates (ΣPNs), total alkyl and multi-functional nitrates (ΣANs) and nitric acid (HNO3, made between 25° and 55° N, confirm a controlling role for peroxyacyl nitrates in NOx production in aged Asian outflow. ΣPNs account for more than 60% of NOy above 5 km, while thermal dissociation limits their contribution to less than 10% in the lower troposphere. Using simultaneous observations of NOx, ΣPNs, ΣANs, HNO3 and average wind speed, we calculate the flux of reactive nitrogen through the meridional plane of 150° W (between 20° and 55° N) to be 0.007 ± 0.002 Tg N day−1, which provides an upper limit of 23 ± 6.5% on the transport efficiency of NOy from East Asia. Observations of NOx, and HOx are used to constrain a 0-D photochemical box model for the calculation of net photochemical ozone production or tendency (Δ O3) as a function of aircraft altitude and NOx concentrations. The model analysis indicates that the photochemical environment of the lower troposphere (altitude < 6 km) over the north Pacific is one of net O3 destruction, with an experimentally determined crossover point between net O3 destruction and net O3 production of 60 pptv NOx. Qualitative indicators of integrated net O3 production derived from simultaneous measurements of O3 and light alkanes (Parrish et al., 1992), also indicate that the north Pacific is, on average, a region of net O3 destruction.

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