Composition and Chemistry

Analysis of urban gas phase ammonia measurements from the 2002 Atlanta Aerosol Nucleation and Real-Time Characterization Experiment (ANARChE)

  1. J. B. Nowak1,2,
  2. L. G. Huey3,
  3. A. G. Russell4,
  4. D. Tian4,
  5. J. A. Neuman1,2,
  6. D. Orsini3,7,
  7. S. J. Sjostedt3,
  8. A. P. Sullivan3,
  9. D. J. Tanner3,
  10. R. J. Weber3,
  11. A. Nenes3,5,
  12. E. Edgerton6,
  13. F. C. Fehsenfeld1,2

Article first published online: 9 SEP 2006

DOI: 10.1029/2006JD007113

Issue

Journal of Geophysical Research: Atmospheres (1984–2012)

Journal of Geophysical Research: Atmospheres (1984–2012)

Volume 111, Issue D17, 16 September 2006

Additional Information

How to Cite

Nowak, J. B., et al. (2006), Analysis of urban gas phase ammonia measurements from the 2002 Atlanta Aerosol Nucleation and Real-Time Characterization Experiment (ANARChE), J. Geophys. Res., 111, D17308, doi:10.1029/2006JD007113.

Author Information

  1. 1

    Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA

  2. 2

    Chemical Sciences Division, Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, Colorado, USA

  3. 3

    School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA

  4. 4

    School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA

  5. 5

    School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA

  6. 6

    Atmospheric Research and Analysis, Inc., Cary, North Carolina, USA

  7. 7

    Now at Department of Chemistry and Biochemistry, Siena College, Loudonville, New York, USA.

Publication History

  1. Issue published online: 9 SEP 2006
  2. Article first published online: 9 SEP 2006
  3. Manuscript Accepted: 22 MAY 2006
  4. Manuscript Revised: 1 MAY 2006
  5. Manuscript Received: 23 JAN 2006

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Keywords:

  • ammonia;
  • chemical ionization mass spectrometry;
  • ANARChE

[1] Gas phase ammonia (NH3) measurements were made in July and August 2002 during the Atlanta Aerosol Nucleation and Real-Time Characterization Experiment with two different chemical ionization mass spectrometry techniques. Correlations between the 1 min data from both instruments yielded a slope of 1.17 and an intercept of −0.295 ppbv, with a linear correlation coefficient (r2) of 0.71. Ambient NH3 mixing ratios ranged from 0.4 to 13 ppbv. NH3 observations were compared to the Community Multiscale Air Quality (CMAQ) modeling system as well as a thermodynamic equilibrium model, ISORROPIA, used by CMAQ to predict NH3 partitioning. A morning rise in both observed and modeled NH3 mixing ratios strongly suggests a regional influence due to automobile emissions. However, at midday the predicted NH3 decreased to less than 0.5 ppbv, while the observations remained around 3 ppbv. Both observed and modeled ammonium nitrate levels were too low to support the observed midday NH3 mixing ratios. ISORROPIA calculations of NH3 constrained by the total measured ammonia mass (NH3 + ammonium (NH4+)) agreed well with the observations (slope of 1.25 and r2 of 0.75). For times when the net aerosol charge was near zero the agreement was excellent (slope of 1.22 and r2 of 0.88). These results indicate that for most of the observed conditions, ISORROPIA could accurately predict NH3 partitioning. The observations suggest that local sunlight- or temperature-driven NH3 sources, such as soil emissions, may be responsible for the discrepancy between the model results and measured values.

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