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Atmospheric Measurement Techniques An interactive open-access journal of the European Geosciences Union
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© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 18 Nov 2019

Submitted as: research article | 18 Nov 2019

Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Atmospheric Measurement Techniques (AMT).

Assessment of NO2 observations during DISCOVER-AQ and KORUS-AQ field campaigns

Sungyeon Choi1,2, Lok N. Lamsal1,3, Melanie Follette-Cook1,4, Joanna Joiner1, Nickolay A. Krotkov1, William H. Swartz5, Kenneth E. Pickering1,6, Christopher P. Loughner6,7, Wyat Appel8, Gabriele Pfister9, Pablo E. Saide10, Ronald C. Cohen11, Andrew J. Weinheimer9, and Jay R. Herman1,12 Sungyeon Choi et al.
  • 1NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
  • 2Science Systems and Applications, Inc., Lanham, MD 20706, USA
  • 3Universities Space Research Association, Columbia, MD 21046, USA
  • 4Morgan State University, Baltimore, MD 20251, USA
  • 5Johns Hopkins University, Applied Physics Laboratory, Laurel, MD 20723, USA
  • 6University of Maryland, College Park, MD 20742, USA
  • 7NOAA Air Resources Laboratory, College Park, MD 20740, USA
  • 8Environmental Protection Agency, Research Triangle Park, NC 27709, USA
  • 9National Center for Atmospheric Research, Boulder, CO 80301, USA
  • 10University of California, Los Angeles, CA 90095, USA
  • 11University of California, Berkeley, CA 94720, USA
  • 12University of Maryland Baltimore County, Baltimore, MD 21250, USA

Abstract. NASA’s Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) campaign in the United States and the joint NASA and National Institute of Environmental Research (NIER) Korea-United States Air Quality Study (KORUS-AQ) in South Korea were two field study programs that provided comprehensive, integrated datasets of airborne and surface observations of atmospheric constituents, including nitrogen dioxide (NO2), with a goal of improving the interpretation of spaceborne remote sensing data. Various types of NO2 measurements were made, including in situ concentrations and column amounts of NO2 using ground- and aircraft-based instruments, while NO2 column amounts were being derived from the Ozone Monitoring Instrument (OMI) on the Aura satellite. This study takes advantage of these unique data sets by first evaluating in situ data taken from two different instruments on the same aircraft platform, comparing coincidently sampled profile-integrated columns from aircraft spirals with remotely sensed column observations from ground-based Pandora spectrometers, intercomparing column observations from the ground (Pandora), aircraft (in situ vertical spirals), and space (OMI), and evaluating NO2 simulations from coarse Global Modeling Initiative (GMI) and high-resolution regional models. We then use these data to interpret observed discrepancies due to differences in sampling and deficiencies in the data reduction process. Finally, we assess satellite retrieval sensitivity to observed and modeled a-priori NO2 profiles. Contemporaneous measurements from two aircraft instruments that likely sample similar air masses generally agree very well but are also found to differ in integrated columns by up to 33.3 %. These show even larger differences with Pandora, reaching up to 53.1 %, potentially due to a combination of strong gradients in NO2 fields that could be missed by aircraft spirals and errors in the Pandora retrievals. OMI NO2 values are about a factor of two lower in these highly polluted environments, due in part to inaccurate retrieval assumptions (e.g., a priori profiles), but mostly to OMI’s areal (> 312 km2) averaging.

Sungyeon Choi et al.
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Status: open (extended)
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Sungyeon Choi et al.
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