EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Validation of Sentinel-5P TROPOMI tropospheric NO2 with airborne imaging, ground-based stationary, and mobile DOAS measurements from the S5P-VAL-DE-Ruhr campaign

Kezia Lange1, Andreas C. Meier1, Michel Van Roozendael2, Thomas Wagner3, Thomas Ruhtz4, Dirk Schüttemeyer5, and the S5p-VAL-DE-Ruhr campaign team*
Kezia Lange et al.
  • 1Institute of Environmental Physics, University of Bremen, Bremen, Germany (
  • 2Royal Belgian Institute for Space Aeronomy, Brussels, Belgium
  • 3Max Planck Institute for Chemistry, Mainz, Germany
  • 4Institute for Space Science, FU Berlin, Berlin, Germany
  • 5European Space Agency, ESA-ESTEC, Noordwijk, Netherlands
  • *A full list of authors appears at the end of the abstract

Airborne imaging DOAS and ground-based stationary and mobile DOAS measurements were conducted during the ESA funded S5P-VAL-DE-Ruhr campaign in September 2020 in the Ruhr area. The Ruhr area is located in Western Germany and is a pollution hotspot in Europe with urban character as well as large industrial emitters. The measurements are used to validate data from the Sentinel-5P TROPOspheric Monitoring Instrument (TROPOMI) with focus on the NO2 tropospheric vertical column product.

Seven flights were performed with the airborne imaging DOAS instrument, AirMAP, providing continuous maps of NO2 in the layers below the aircraft. These flights cover many S5P ground pixels within an area of about 40 km side length and were accompanied by ground-based stationary measurements and three mobile car DOAS instruments. Stationary measurements were conducted by two Pandora, two zenith-sky and two MAX-DOAS instruments distributed over three target areas, partly as long-term measurements over a one-year period.

Airborne and ground-based measurements were compared to evaluate the representativeness of the measurements in time and space. With a resolution of about 100 x 30 m2, the AirMAP data creates a link between the ground-based and the TROPOMI measurements with a resolution of 3.5 x 5.5 km2 and is therefore well suited to validate TROPOMI's tropospheric NO2 vertical column.

The measurements on the seven flight days show strong variability depending on the different target areas, the weekday and meteorological conditions. We found an overall low bias of the TROPOMI operational NO2 data for all three target areas but with varying magnitude for different days. The campaign data set is compared to custom TROPOMI NO2 products, using different auxiliary data, such as albedo or a priori vertical profiles to evaluate the influence on the TROPOMI data product. Analyzing and comparing the different data sets provides more insight into the high spatial and temporal heterogeneity in NO2 and its impact on satellite observations and their validation.

S5p-VAL-DE-Ruhr campaign team:

Lisa Behrens (1), Christian Borger (3), Tim Bösch (1), John P. Burrows (1), Ermioni Dimitropoulou (2), Sebastian Donner (3), Steffen Dörner (3), Kai Krause (1), Vinod Kumar (3), Bianca Lauster (3), Alexis Merlaud (2), Maria Razi (3), Andreas Richter (1), Anja Schönhardt (1), André Seyler (1), Frederik Tack (2), Katharina Uhlmannsiek (3), Folkard Wittrock (1)

How to cite: Lange, K., Meier, A. C., Van Roozendael, M., Wagner, T., Ruhtz, T., and Schüttemeyer, D. and the S5p-VAL-DE-Ruhr campaign team: Validation of Sentinel-5P TROPOMI tropospheric NO2 with airborne imaging, ground-based stationary, and mobile DOAS measurements from the S5P-VAL-DE-Ruhr campaign, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10637,, 2021.

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