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

Evaluation of a high resolution regional atmospheric chemistry model using MAX-DOAS and in situ NO2 measurements

Vinod Kumar1, Julia Remmers1, Steffen Beirle1, Astrid Kerkweg2, Jos Lelieveld1, Mariano Mertens3, Andrea Pozzer1, Benedikt Steil1, and Thomas Wagner1
Vinod Kumar et al.
  • 1Max Planck Institute for Chemistry, Satellite Remote Sensing, Mainz, Germany (
  • 2Institute of Energy and Climate Research 8, Troposphere, Forschungszentrum Jülich, Jülich, Germany
  • 3Deutsches Zentrum für Luft- und Raumfahrt, Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany

Regional atmospheric chemistry models are adopted for simulating concentrations of atmospheric components at high resolution and quantifying the impact of localized emissions (e.g. industrial and urban clusters) on the non-linear chemical processes, e.g. ozone production. However, their evaluation is challenging due to the limited availability of high spatiotemporally resolved reference datasets. For the same reason, the vertical distribution of pollutants simulated by the model is especially arduous to assess.

Here, we present regional atmospheric chemistry model studies with spatial resolution up to 2.2 × 2.2 km2 focused around Germany for May 2018 using the MECO(n) model system. Using a network of surface concentration measurements at background, near traffic and industrial locations, we evaluate the spatial distribution of NO2 simulated by the model. The highly resolved model together with a comparable resolution and up-to-date input emissions inventory, was found to perform best in reproducing the spatial distribution of NO2 surface volume mixing ratios (VMRs). We propose a computationally efficient approach to account for the diurnal and day of the week variability of input anthropogenic emissions (e.g. from road transport), which proved to be crucial for resolving the temporal variability of NO2 surface VMRs.

The simulated NO2 tropospheric vertical column densities were evaluated by employing the measurements of a 4-azimuth MAX-DOAS instrument in Mainz. Generally, such comparisons do not account for the spatial sensitivity volume of the MAX-DOAS measurements, the change of sensitivity within this volume and the spatial heterogeneity of NO2. We therefore apply a consistent approach of comparison of the differential slant column densities (dSCDs), which overcomes these limitations. Moreover, the dSCDs are obtained for several elevation and azimuth angles, which are characterized by distinctive sensitivity for different vertical levels within the boundary layer and different horizontal representativeness. Hence, also an evaluation of the model in simulating the vertical distribution of NO2 can be performed with this approach using continuous MAX-DOAS measurements spanning long time periods. We found that the model performs well with respect to the measured dSCDs at low elevation angles (< 8°) with an overall bias between +14 and -9%, and Pearson correlation coefficients between 0.5 and 0.8 for the different azimuth viewing directions.

How to cite: Kumar, V., Remmers, J., Beirle, S., Kerkweg, A., Lelieveld, J., Mertens, M., Pozzer, A., Steil, B., and Wagner, T.: Evaluation of a high resolution regional atmospheric chemistry model using MAX-DOAS and in situ NO2 measurements, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4989,, 2021.