EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Long open-path measurements of CO2 and CH4 with an 125HR FTS in an urban environment.

Tobias Schmitt1, Jonas Kuhn1, Lukas Pilz1, Robert Maiwald1, Maximilian May1, Ralph Kleinschek1, Paul Edinger1, Stefan Schmitt2, Frank Hase3, David W. T. Griffith4, and André Butz1
Tobias Schmitt et al.
  • 1Institute of Environmental Physics, Heidelberg University, Heidelberg, Germany
  • 2Airyx GmbH, Heidelberg, Germany
  • 3Institute for Meteorology and Climate Research, Karlsruhe Institute of Technology, Karlsruhe, Germany
  • 4Centre for Atmospheric Chemistry, University of Wollongong, Wollongong, Australia

Quantifying sources and sinks, as well as chemical activity of trace gases in the lower troposphere, requires accurate measurements of the concentrations of the species of interest. While there exist in-situ measurement techniques, which are highly accurate, point-like measurements are only sufficiently representative in the spatial domain for a small area. This holds true in particular in high-gradient environments, e.g., urban settings. Hence, measuring those concentrations averaged on the length scale of a few kilometers is desirable. Furthermore, quantifying emissions requires combining concentration measurements with regional transport models, which cover a comparable spatial resolution.

We present a long open-path setup that measures average concentrations on the kilometer-scale in the urban boundary layer. Our setup, which is operational since March 2022, is based on a Bruker IFS 125 HR Fourier transform spectrometer, a commercially available spectrometer, which offers high resolution and throughput. The instrument choice provides flexible and explorative experimental setups such as variable and high spectral resolution and the extension of spectral coverage from the shortwave-infrared to the near ultra-violet spectral range. Here, we present the results on CO2 and CH4 from our 2022 measurement campaign as well as analysis of the diurnal variability in comparison to the prediction of local and regional transport models.

How to cite: Schmitt, T., Kuhn, J., Pilz, L., Maiwald, R., May, M., Kleinschek, R., Edinger, P., Schmitt, S., Hase, F., Griffith, D. W. T., and Butz, A.: Long open-path measurements of CO2 and CH4 with an 125HR FTS in an urban environment., EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-4403,, 2023.