On the effectiveness of nitrogen oxide reductions as a control over ammonium nitrate aerosol

S. E. Pusede; S. E. Pusede; K. C. Duffey; A. A. Shusterman; A. Saleh; J. L. Laughner; P. J. Wooldridge; Q. Zhang; C. L. Parworth; H. Kim; S. L. Capps; L. C. Valin; C. D. Cappa; A. Fried; J. Walega; J. B. Nowak; A. J. Weinheimer; R. M. Hoff; T. A. Berkoff; A. J. Beyersdorf; J. Olson; J. H. Crawford; R. C. Cohen; R. C. Cohen

doi:10.5194/acp-16-2575-2016

Atmospheric Chemistry and Physics (Mar 2016)

On the effectiveness of nitrogen oxide reductions as a control over ammonium nitrate aerosol

S. E. Pusede,
S. E. Pusede,
K. C. Duffey,
A. A. Shusterman,
A. Saleh,
J. L. Laughner,
P. J. Wooldridge,
Q. Zhang,
C. L. Parworth,
H. Kim,
S. L. Capps,
L. C. Valin,
C. D. Cappa,
A. Fried,
J. Walega,
J. B. Nowak,
A. J. Weinheimer,
R. M. Hoff,
T. A. Berkoff,
A. J. Beyersdorf,
J. Olson,
J. H. Crawford,
R. C. Cohen,
R. C. Cohen

Affiliations

S. E. Pusede: Department of Chemistry, University of California Berkeley, Berkeley, CA 94720, USA
S. E. Pusede: now at: Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22904, USA
K. C. Duffey: Department of Chemistry, University of California Berkeley, Berkeley, CA 94720, USA
A. A. Shusterman: Department of Chemistry, University of California Berkeley, Berkeley, CA 94720, USA
A. Saleh: Department of Chemistry, University of California Berkeley, Berkeley, CA 94720, USA
J. L. Laughner: Department of Chemistry, University of California Berkeley, Berkeley, CA 94720, USA
P. J. Wooldridge: Department of Chemistry, University of California Berkeley, Berkeley, CA 94720, USA
Q. Zhang: Department of Environmental Toxicology, University of California at Davis, Davis, CA 95616, USA
C. L. Parworth: Department of Environmental Toxicology, University of California at Davis, Davis, CA 95616, USA
H. Kim: Center for Environment, Health and Welfare Research, Korea Institute of Science and Technology, Seoul, Korea
S. L. Capps: Department of Mechanical Engineering, University of Colorado Boulder, Boulder, CO 80309, USA
L. C. Valin: Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA
C. D. Cappa: Department of Civil and Environmental Engineering, University of California at Davis, Davis, CA 95616, USA
A. Fried: Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO 80309, USA
J. Walega: Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO 80309, USA
J. B. Nowak: Aerodyne Research, Inc., Billerica, Billerica, MA 01821, USA
A. J. Weinheimer: Atmospheric Chemistry Division, National Center for Atmospheric Research, Boulder, CO 80307, USA
R. M. Hoff: Department of Physics, University of Maryland Baltimore County, Baltimore, MD 21250, USA
T. A. Berkoff: NASA Langley Research Center, Hampton, VA 23681, USA
A. J. Beyersdorf: NASA Langley Research Center, Hampton, VA 23681, USA
J. Olson: NASA Langley Research Center, Hampton, VA 23681, USA
J. H. Crawford: NASA Langley Research Center, Hampton, VA 23681, USA
R. C. Cohen: Department of Chemistry, University of California Berkeley, Berkeley, CA 94720, USA
R. C. Cohen: Department of Earth and Planetary Science, University of California Berkeley, Berkeley, CA 94720, USA

DOI: https://doi.org/10.5194/acp-16-2575-2016
Journal volume & issue: Vol. 16
pp. 2575 – 2596

Abstract

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Nitrogen oxides (NOx) have fallen steadily across the US over the last 15 years. At the same time, NOx concentrations decrease on weekends relative to weekdays, largely without co-occurring changes in other gas-phase emissions, due to patterns of diesel truck activities. These trends taken together provide two independent constraints on the role of NOx in the nonlinear chemistry of atmospheric oxidation. In this context, we interpret interannual trends in wintertime ammonium nitrate (NH4NO3) in the San Joaquin Valley of California, a location with the worst aerosol pollution in the US and where a large portion of aerosol mass is NH4NO3. Here, we show that NOx reductions have simultaneously decreased nighttime and increased daytime NH4NO3 production over the last decade. We find a substantial decrease in NH4NO3 since 2000 and conclude that this decrease is due to reduced nitrate radical-initiated production at night in residual layers that are decoupled from fresh emissions at the surface. Further reductions in NOx are imminent in California, and nationwide, and we make a quantitative prediction of the response of NH4NO3. We show that the combination of rapid chemical production and efficient NH4NO3 loss via deposition of gas-phase nitric acid implies that high aerosol days in cities in the San Joaquin Valley air basin are responsive to local changes in NOx within those individual cities. Our calculations indicate that large decreases in NOx in the future will not only lower wintertime NH4NO3 concentrations but also cause a transition in the dominant NH4NO3 source from nighttime to daytime chemistry.

Published in Atmospheric Chemistry and Physics

ISSN: 1680-7316 (Print); 1680-7324 (Online)
Publisher: Copernicus Publications
Country of publisher: Germany
LCC subjects: Science: Physics; Science: Chemistry
Website: http://www.atmospheric-chemistry-and-physics.net/

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