Validation of Aura-OMI QA4ECV NO₂ climate data records with ground-based DOAS networks: the role of measurement and comparison uncertainties

Steven Compernolle (1) , Tiji Verhoelst (1) , Gaia Pinardi (1) , José Granville (1) , Daan Hubert (1) , Arno Keppens (1) , Sander Niemeijer (2) , Bruno Rino (2) , Alkis Bais (3) , Steffen Beirle (4) , Folkert Boersma (5, 6) , John P. Burrows (7) , Isabelle de Smedt (1) , Henk Eskes (5) , Florence Goutail (8) , François Hendrick (1) , Alba Lorente (6) , Andrea Pazmino (8) , Ankie Piters (5) , Enno Peters (7) , Jean-Pierre Pommereau (8) , Julia Remmers (9) , Andreas Richter (7) , Jos van Geffen (5) , Michel van Roozendaël (1) , Thomas Wagner (9) , Jean-Christopher Lambert (1)

1 BIRA-IASB - Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique
2 S [&] T - Science [&] Technology Corporation [Delft]
3 Laboratory of Atmospheric Physics [Thessaloniki]
4 MPIC - Max-Planck-Institut für Chemie
5 KNMI - Royal Netherlands Meteorological Institute
6 Meteorology and Air Quality Group
7 IUP - Institute of Environmental Physics [Bremen]
8 STRATO - LATMOS
9 MPIC - Max Planck Institute for Chemistry

The QA4ECV version 1.1 stratospheric and tropospheric NO2 vertical column density (VCD) climate data records (CDR) from the satellite sensor OMI are validated, using NDACC zenith scattered light DOAS (ZSL-DOAS) and Multi Axis-DOAS (MAX-DOAS) data as a reference. The QA4ECV OMI stratospheric VCD have a small bias of ~ 0.2 Pmolec cm-2 (5–10 %) and a dispersion of 0.2 to 1 Pmolec cm-2 with respect to the ZSL-DOAS measurements. QA4ECV tropospheric VCD observations from OMI are restricted to near-cloud-free scenes, leading to a negative sampling bias (with respect to the unrestricted scene ensemble) of a few Pmolec cm-2 up to −10 Pmolec cm-2 (−40 %) in one extreme high-pollution case. QA4ECV OMI tropospheric VCD has a negative bias with respect to the MAX-DOAS data (−1 to −4 Pmolec cm-2), a feature also found for the OMI OMNO2 standard data product. The tropospheric VCD discrepancies between satellite and ground-based data exceed by far the combined measurement uncertainties. Depending on the site, part of the discrepancy can be attributed to a combination of comparison errors (notably horizontal smoothing difference error), measurement/retrieval errors related to clouds and aerosols, and to the difference in vertical smoothing and a priori profile assumptions.

Domaines: Physique Atmosphérique et Océanique [physics.ao-ph]; Climatologie

Steven Compernolle, Tiji Verhoelst, Gaia Pinardi, José Granville, Daan Hubert, et al.. Validation of Aura-OMI QA4ECV NO₂ climate data records with ground-based DOAS networks: the role of measurement and comparison uncertainties. Atmospheric Chemistry and Physics, 2020, 20 (13), pp.8017-8045. ⟨10.5194/acp-20-8017-2020⟩. ⟨insu-02426287⟩