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Atmospheric Measurement Techniques An interactive open-access journal of the European Geosciences Union
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© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

  29 Jun 2020

29 Jun 2020

Review status
This preprint is currently under review for the journal AMT.

OMI/Aura Nitrogen Dioxide Standard Product with Improved Surface and Cloud Treatments

Lok N. Lamsal1,2, Nickolay A. Krotkov2, Alexander Vasilkov2,3, Sergey Marchenko2,3, Wenhan Qin2,3, Eun-Su Yang2,3, Zachary Fasnacht2,3, Joanna Joiner2, Sungyeon Choi2,3, David Haffner2,3, William H. Swartz4, Bradford Fisher2,3, and Eric Bucsela5 Lok N. Lamsal et al.
  • 1University Space Research Association, Greenbelt, MD 20770, USA
  • 2NASA Goddard Space Flight Center, Greenbelt, MD 20770, USA
  • 3Science Systems and Applications, Lanham, MD 20706, USA
  • 4Johns Hopkins University, Applied Physics Laboratory, Laurel, MD 20723, USA
  • 5SRI International, Menlo Park, CA 94025, USA

Abstract. We present a new and improved version (V4.0) of the NASA standard nitrogen dioxide (NO2) product from the Ozone Monitoring Instrument (OMI) on the Aura satellite. This version incorporates the most salient improvements for regional OMI NO2 products suggested by expert users, and enhances the NO2 data quality in several ways on a global scale through improvements to the air mass factors (AMFs) used in the retrieval algorithm. The algorithm is based on a conceptually new, geometry-dependent surface Lambertian equivalent reflectivity (GLER) operational product that is available on an OMI pixel basis. GLER is calculated using the vector linearized discrete ordinate radiative transfer (VLIDORT) model, which uses as input high resolution bidirectional reflectance distribution function (BRDF) information from NASA’s Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) instruments over land and the wind-dependent Cox–Munk wave-facet slope distribution over water, the latter with contribution from the water-leaving radiance. The GLER combined with consistently retrieved oxygen dimer (O2-O2) absorption-based cloud fractions and pressures provide high-quality data inputs to the new NO2 AMF scheme. The new AMFs increase the retrieved tropospheric NO2 by up to 50 % in highly polluted areas; these differences arise from both cloud and surface BRDF effects as well as biases between the new MODIS-based and previously used OMI-based climatological surface reflectance data sets. We quantitatively evaluate the new NO2 product using independent observations from ground-based and airborne instruments. The improved NO2 data record can be used for studies related to emissions and trends of nitrogen oxides (NOx) and co-emitted gases. The new V4.0 data and relevant explanatory documentation are publicly available from the NASA Goddard Earth Sciences Data and Information Services Center (, and we encourage their use over previous versions of OMI NO2 products.

Lok N. Lamsal et al.

Interactive discussion

Status: final response (author comments only)
Status: final response (author comments only)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
  • RC1: 'Review', Anonymous Referee #1, 03 Aug 2020 Printer-friendly Version
  • RC2: 'Review', Anonymous Referee #2, 27 Aug 2020 Printer-friendly Version

Lok N. Lamsal et al.

Data sets

OMI/Aura Nitrogen Dioxide (NO2) Total and Tropospheric Column 1-orbit L2 Swath 13x24 km V003 N. A. Krotkov, L. N. Lamsal, S. V. Marchenko, E. A. Celarier, E. J. Bucsela, W. H. Swartz, J. Joiner, and the OMI core team

Lok N. Lamsal et al.


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Latest update: 23 Sep 2020
Publications Copernicus
Short summary
The NASA standard nitrogen dioxide (NO2) version 4.0 product for OMI Aura incorporates the most salient improvements. It represents the first global satellite trace-gas retrieval with OMI-MODIS synergy accounting for surface reflectance anisotropy in cloud and NO2 retrievals. Improved spectral fitting procedures for NO2 and oxygen dimer (for cloud) retrievals and reliance on high resolution field of view specific input information for NO2 and cloud retrievals help enhance the NO2 data quality.
The NASA standard nitrogen dioxide (NO2) version 4.0 product for OMI Aura incorporates the most...