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Atmospheric Measurement Techniques An interactive open-access journal of the European Geosciences Union
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Volume 11, issue 8 | Copyright
Atmos. Meas. Tech., 11, 4583-4603, 2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 08 Aug 2018

Research article | 08 Aug 2018

NO2 and HCHO measurements in Korea from 2012 to 2016 from Pandora spectrometer instruments compared with OMI retrievals and with aircraft measurements during the KORUS-AQ campaign

Jay Herman1, Elena Spinei2, Alan Fried3, Jhoon Kim4, Jae Kim5, Woogyung Kim3, Alexander Cede6, Nader Abuhassan1, and Michal Segal-Rozenhaimer7,8 Jay Herman et al.
  • 1JCET, University of Maryland Baltimore County, Baltimore, MD, USA
  • 2Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
  • 3Institute of Arctic & Alpine Research, University of Colorado, Boulder, Colorado, USA
  • 4Dept. of Atmospheric Sciences, Yonsei University, Seoul, Korea
  • 5Department of Atmospheric Science, Pusan University, Busan, Korea
  • 6Goddard Earth Sciences Technology & Research (GESTAR) Columbia, Columbia, Maryland, USA
  • 7Earth Science Division, NASA Ames, Mountain View, California, USA
  • 8Bay Area Environmental Research Institute, Petaluma, California, USA

Abstract. Nine Pandora spectrometer instruments (PSI) were installed at eight sites in South Korea as part of the KORUS-AQ (Korea U.S.-Air Quality) field study integrating information from ground, aircraft, and satellite measurements for validation of remote sensing air-quality studies. The PSI made direct-sun measurements of total vertical column NO2, C(NO2), with high precision (0.05DU, where 1DU = 2.69×1016moleculescm−2) and accuracy (0.1DU) that were retrieved using spectral fitting techniques. Retrieval of formaldehyde C(HCHO) total column amounts were also obtained at five sites using the recently improved PSI optics. The C(HCHO) retrievals have high precision, but possibly lower accuracy than for NO2 because of uncertainty about the optimum spectral window for all ground-based and satellite instruments. PSI direct-sun retrieved values for C(NO2) and C(HCHO) are always significantly larger than OMI (AURA satellite Ozone Monitoring Instrument) retrieved C(NO2) and C(HCHO) for the OMI overpass local times (KST = 13.5±0.5h). In urban areas, PSI C(NO2) 30-day running averages are at least a factor of two larger than OMI averages. Similar differences are seen for C(HCHO) in Seoul and nearby surrounding areas. Late afternoon values of C(HCHO) measured by PSI are even larger, implying that OMI early afternoon measurements underestimate the effect of poor air quality on human health. The primary cause of OMI underestimates is the large OMI field of view (FOV) that includes regions containing low values of pollutants. In relatively clean areas, PSI and OMI are more closely in agreement. C(HCHO) amounts were obtained for five sites, Yonsei University in Seoul, Olympic Park, Taehwa Mountain, Amnyeondo, and Yeoju. Of these, the largest amounts of C(HCHO) were observed at Olympic Park and Taehwa Mountain, surrounded by significant amounts of vegetation. Comparisons of PSI C(HCHO) results were made with the Compact Atmospheric Multispecies Spectrometer CAMS during overflights on the DC-8 aircraft for Taehwa Mountain and Olympic Park. In all cases, PSI measured substantially more C(HCHO) than obtained from integrating the CAMS altitude profiles. PSI C(HCHO) at Yonsei University in Seoul frequently reached 0.6DU and occasionally exceeded 1.5DU. The semi-rural site, Taehwa Mountain, frequently reached 0.9DU and occasionally exceeded 1.5DU. Even at the cleanest site, Amnyeondo, C(HCHO) occasionally exceeded 1DU.

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Short summary
Nine Pandora Spectrometer Instruments were installed at 8 sites for KORUS-AQ (Korea U.S.-Air Quality) field study from ground, aircraft, and satellite measurements. The quantities retrieved were total column measurements of ozone, nitrogen dioxide, and formaldehyde. We show the distribution of NO2 and HCHO air pollutants vs location and time of day and comparisons with aircraft and satellite data. For some of the sites, long-term time series are available to asses changes.
Nine Pandora Spectrometer Instruments were installed at 8 sites for KORUS-AQ (Korea U.S.-Air...