EGU23-3818
https://doi.org/10.5194/egusphere-egu23-3818
EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Towards more realistic modelling of tropospheric NO2 with WRF-Chem using fine-tuned temporal emission profiles

Leon Kuhn1,2, Steffen Beirle1, Vinod Kumar1, Sergey Osipov1,3, Andrea Pozzer1, Tim Bösch4, Rajesh Kumar5, and Thomas Wagner1,2
Leon Kuhn et al.
  • 1Max Planck Institute for Chemistry, Satellite Group, Mainz, Germany
  • 2Institute for Environmental Physics, University of Heidelberg, Germany
  • 3Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
  • 4Institute for Environmental Physics, University of Bremen, Germany
  • 5National Center for Atmospheric Research, Boulder, United States of America

NO2 is an important air pollutant and has been recognized for its hazardous impact on human health. Although routine in-situ measurements of NO2 are available in many regions of the earth, models for regional chemistry and transport (RCT) are often used to predict trace gas concentrations where no direct measurements are available. An important aspect of realistic NO2 modelling is to use accurate NOx emissions with high temporal resolution. The standard practice is to use a monthly or yearly resolved emission inventory in combination with sector-specific hourly emission weights (“temporal profiles”) in order to simulate diurnal, weekly, and seasonal emission patterns. Temporal profiles are typically derived from empirical data, e.g. car counts on highways, and have been known to improve RCT simulations significantly. Nonetheless, in comparison against in-situ measurements, simulated NO2 concentrations are usually too low at daytime and too high at nighttime, with relative deviations of up to 50 %. This hints towards faulty temporal emission profiles.

We present a novel method to determine improved temporal emission profiles for NOx emissions in a WRF-Chem simulation for May 2019 in central Europe. The temporal profiles are determined in an iterative procedure that consists of running the simulation, comparing the simulated NOx concentrations to in-situ reference measurements, and adjusting the hourly temporal profiles to compensate deviations between simulation and reference values. In a subsequent intercomparison of model results with observational datasets (surface concentrations from in-situ measurements, tropospheric vertical column densities from the TROPOMI satellite instrument, and concentration profiles from MAX-DOAS retrievals), we validate our simulation results. In particular, the typical NO2 underestimation at noontime is resolved and the monthly average of simulated vertical column densities deviates less than 7% from the TROPOMI reference data.

How to cite: Kuhn, L., Beirle, S., Kumar, V., Osipov, S., Pozzer, A., Bösch, T., Kumar, R., and Wagner, T.: Towards more realistic modelling of tropospheric NO2 with WRF-Chem using fine-tuned temporal emission profiles, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-3818, https://doi.org/10.5194/egusphere-egu23-3818, 2023.