Tropospheric Chemistry: Instruments

NH3 instrument in aircraft

NH3 instrument (right) mounted in NOAA WP-3D aircraft.

Ammonia (NH3) CIMS

Principle of the Measurement

Chemical Ionization Mass Spectrometry (CIMS) using protonated acetone dimer ((C3H6O)H+(C3H6O)) ion chemistry

Species Measured


Time Response

1-5 s depending on field project

Detection Limit

Precision on 1 s data: 35 - 80 pptv (1 sigma) depending on field project


±(25% + (70-500 pptv)) depending on field project


custom built

Field Projects

  • ANARChE 2002 (non-NOAA project)
  • ICARTT 2004
  • TexAQS 2006
  • 2008 ARCPAC (to measure nitric acid, sulfur dioxide, and halogens with SF6- ion chemistry)
  • CalNex 2010
  • SENEX 2013
  • SONGNEX 2015


  • NOAA WP-3D aircraft


Scott Eilerman

Key Publications

Nowak, J. B., J. A. Neuman, R. Bahreini, A. M. Middlebrook, J. S. Holloway, S. A. McKeen, D. D. Parrish, T. B. Ryerson, and M. Trainer, Ammonia sources in the California South Coast Air Basin and their impact on ammonium nitrate formation, Geophys. Res. Lett., doi:10.1029/2012GL051197, 2012.

Neuman, J. A., T. B. Ryerson, L. G. Huey, R. Jakoubek, J. B. Nowak, C. Simons, and F. C. Fehsenfeld, Calibration and evaluation of nitric acid and ammonia permeation tubes by UV optical absorption, Environ. Sci. Technol., doi:10.1021/ES06422L, 2003.

Nowak, J. B., L. G. Huey, A. G. Russell, D. Tian, J. A. Neuman, D. Orsini, S. J. Sjostedt, A. P. Sullivan, D. J. Tanner, R. J. Weber, A. Nenes, E. Edgerton, F. C. Fehsenfeld, Analysis of urban gas phase ammonia measurements from the 2002 Atlanta Aerosol Nucleation and Real-Time Characterization Experiment (ANARChE), J. Geophys. Res., doi:10.1029/2006JD007113, 2006.

Nowak, J. B., J. A. Neuman, K. Kozai, L. G. Huey, D. J. Tanner, J. S. Holloway, T. B. Ryerson, G. J. Frost, S. A. McKeen, and F. C. Fehsenfeld, A chemical ionization mass spectrometry technique for airborne measurements of ammonia, J. Geophys. Res., doi:10.1029/2006JD007589, 2007.

Nowak, J. B., J. A. Neuman, R. Bahreini, C. A. Brock, A. M. Middlebrook, A. G. Wollny, J. S. Holloway, J. Peischl, T. B. Ryerson, and F. C. Fehsenfeld, Airborne observations of ammonia and ammonium nitrate formation over Houston, Texas, J. Geophys. Res., doi:10.1029/2010JD014195, 2010.