Comparison of airborne measurements of NO, NO2, HONO, NOy and CO during FIREX-AQ
- 1Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO, USA
- 2NOAA Chemical Sciences Laboratory (CSL), Boulder, CO, USA
- 3Department of Chemistry, University of Colorado Boulder, Boulder, CO, USA
- 4Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
- 5NASA Langley Research Center, Hampton, VA, USA
- 6Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD, USA
- 7Department of Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee, FL, USA
- 8School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA
- 9Department of Atmospheric Science, Colorado State University, Fort Collins, CO, USA
- 10Department of Chemistry and Biochemistry, University of Montana, Missoula, MT, USA
- 11Joint Center for Earth Systems Technology, University of Maryland Baltimore County, Baltimore, MD, USA
- 12Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
- 13Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA, USA
- anow at: Institute of Energy and Climate Research, IEK-8: Troposphere, Forschungszentrum Jülich GmbH, Jülich, Germany
- bnow at: Office of Research and Development, US EPA, Research Triangle Park, NC, USA
- cnow at: Department of Chemistry and Biochemistry, Weber State University, Ogden, UT, USA
- dnow at: Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO, USA
- enow at: NOAA Chemical Sciences Laboratory (CSL), Boulder, CO, USA
- fnow at: Department of Chemistry, University of Colorado Boulder, Boulder, CO, USA
- gnow at: Scientific Aviation, Boulder, CO, USA
Abstract. We present a comparison of fast-response instruments installed onboard the NASA DC-8 aircraft that measured nitrogen oxides (NO and NO2), nitrous acid (HONO), total reactive odd nitrogen (measured both as the total (NOy) and from the sum of individually measured species (SNOy)) and carbon monoxide (CO) in the troposphere during the 2019 Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) campaign. By targeting smoke from summertime wildfires, prescribed fires and agricultural burns across the continental United States, FIREX-AQ provided a unique opportunity to investigate measurement accuracy in concentrated plumes where hundreds of species coexist. Here, we compare NO measurements by chemiluminescence (CL) and laser induced fluorescence (LIF); NO2 measurements by CL, LIF and cavity enhanced spectroscopy (CES); HONO measurements by CES and iodide-adduct chemical ionization mass spectrometry (CIMS); and CO measurements by tunable diode laser absorption spectrometry (TDLAS) and integrated cavity output spectroscopy (ICOS). Additionally, total NOy measurements using the CL instrument were compared with SNOy (= NO + NO2 + HONO + nitric acid (HNO3) + acyl peroxy nitrates (APNs) + submicron particulate nitrate (pNO3)). The aircraft instrument intercomparisons demonstrate the following: 1) NO measurements by CL and LIF agreed well within instrument uncertainties, but with potentially reduced time response for the CL instrument; 2) NO2 measurements by LIF and CES agreed well within instrument uncertainties, but CL NO2 was on average 10 % higher; 3) CES and CIMS HONO measurements were highly correlated in each fire plume transect, but the correlation slope of CES vs. CIMS for all 1 Hz data during FIREX-AQ was 1.8, which we attribute to a reduction in the CIMS sensitivity to HONO in high temperature environments; 4) NOy budget closure was demonstrated for all flights within the combined instrument uncertainties of 25 %. However, we used a fluid dynamic flow model to estimate that average pNO3 sampling fraction through the NOy inlet in smoke was variable from one flight to another and ranged between 0.36 and 0.99, meaning that approximately 0–24 % on average of the total measured NOy in smoke may have been unaccounted for and may be due to unmeasured species such as organic nitrates; 5) CO measurements by ICOS and TDLAS agreed well within combined instrument uncertainties, but with a systematic offset that averaged 2.87 ppbv; and 6) integrating smoke plumes followed by fitting the integrated values of each plume improved the correlation between independent measurements.
Ilann Bourgeois et al.
Ilann Bourgeois et al.
Ilann Bourgeois et al.
Viewed (geographical distribution)