Reactive nitrogen partitioning and its relationship to winter ozone events in Utah
R. J. Wild1,2,P. M. Edwards1,2,a,T. S. Bates3,4,R. C. Cohen5,J. A. de Gouw1,2,W. P. Dubé1,2,J. B. Gilman1,2,J. Holloway1,2,J. Kercher6,A. R. Koss1,2,L. Lee5,B. M. Lerner1,2,R. McLaren7,P. K. Quinn3,J. M. Roberts2,J. Stutz8,J. A. Thornton9,P. R. Veres1,2,C. Warneke1,2,E. Williams2,C. J. Young1,2,b,B. Yuan1,2,K. J. Zarzana1,2,and S. S. Brown2,10R. J. Wild et al. R. J. Wild1,2,P. M. Edwards1,2,a,T. S. Bates3,4,R. C. Cohen5,J. A. de Gouw1,2,W. P. Dubé1,2,J. B. Gilman1,2,J. Holloway1,2,J. Kercher6,A. R. Koss1,2,L. Lee5,B. M. Lerner1,2,R. McLaren7,P. K. Quinn3,J. M. Roberts2,J. Stutz8,J. A. Thornton9,P. R. Veres1,2,C. Warneke1,2,E. Williams2,C. J. Young1,2,b,B. Yuan1,2,K. J. Zarzana1,2,and S. S. Brown2,10
1Cooperative Institute for Research in the Environmental Sciences, University of Colorado, Boulder, Colorado 80309, USA
2Chemical Sciences Division, Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, Colorado 80305, USA
3Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration, Seattle, Washington 98115, USA
4Joint Institute for the Study of the Atmosphere and Oceans, University of Washington, Seattle, Washington 98195, USA
5Department of Chemistry, University of California, Berkeley, California 94720, USA
6Department of Chemistry, Hiram College, Hiram, Ohio 44234, USA
7Centre for Atmospheric Chemistry and Chemistry Department, York University, Toronto, Ontario, M3J 1P3, Canada
8Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, California 90095, USA
9Department of Atmospheric Sciences, University of Washington, Seattle, Washington 98195, USA
10Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309 USA
anow at: Department of Chemistry, University of York, York, YO10 5DD, UK
bnow at: Department of Chemistry, Memorial University of Newfoundland, St. John's, Newfoundland, A1B 3X7, Canada
1Cooperative Institute for Research in the Environmental Sciences, University of Colorado, Boulder, Colorado 80309, USA
2Chemical Sciences Division, Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, Colorado 80305, USA
3Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration, Seattle, Washington 98115, USA
4Joint Institute for the Study of the Atmosphere and Oceans, University of Washington, Seattle, Washington 98195, USA
5Department of Chemistry, University of California, Berkeley, California 94720, USA
6Department of Chemistry, Hiram College, Hiram, Ohio 44234, USA
7Centre for Atmospheric Chemistry and Chemistry Department, York University, Toronto, Ontario, M3J 1P3, Canada
8Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, California 90095, USA
9Department of Atmospheric Sciences, University of Washington, Seattle, Washington 98195, USA
10Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309 USA
anow at: Department of Chemistry, University of York, York, YO10 5DD, UK
bnow at: Department of Chemistry, Memorial University of Newfoundland, St. John's, Newfoundland, A1B 3X7, Canada
Correspondence: S. S. Brown (steven.s.brown@noaa.gov)
Received: 14 Jul 2015 – Discussion started: 07 Aug 2015 – Revised: 23 Oct 2015 – Accepted: 08 Dec 2015 – Published: 19 Jan 2016
Abstract. High wintertime ozone levels have been observed in the Uintah Basin, Utah, a sparsely populated rural region with intensive oil and gas operations. The reactive nitrogen budget plays an important role in tropospheric ozone formation. Measurements were taken during three field campaigns in the winters of 2012, 2013 and 2014, which experienced varying climatic conditions. Average concentrations of ozone and total reactive nitrogen were observed to be 2.5 times higher in 2013 than 2012, with 2014 an intermediate year in most respects. However, photochemically active NOx (NO + NO2) remained remarkably similar all three years. Nitric acid comprised roughly half of NOz ( ≡ NOy − NOx) in 2013, with nighttime nitric acid formation through heterogeneous uptake of N2O5 contributing approximately 6 times more than daytime formation. In 2012, N2O5 and ClNO2 were larger components of NOz relative to HNO3. The nighttime N2O5 lifetime between the high-ozone year 2013 and the low-ozone year 2012 is lower by a factor of 2.6, and much of this is due to higher aerosol surface area in the high-ozone year of 2013. A box-model simulation supports the importance of nighttime chemistry on the reactive nitrogen budget, showing a large sensitivity of NOx and ozone concentrations to nighttime processes.
High wintertime ozone levels have been observed in the Uintah Basin, Utah, a sparsely populated rural region with intensive oil and gas operations. The reactive nitrogen budget plays an important role in tropospheric ozone formation, and we find that nighttime chemistry has a large effect on its partitioning. Much of the oxidation of reactive nitrogen during a high-ozone year occurred via heterogeneous uptake onto aerosol at night, keeping NOx at concentrations comparable to a low-ozone year.
High wintertime ozone levels have been observed in the Uintah Basin, Utah, a sparsely populated...
