EGU21-16119, updated on 04 Mar 2021
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Integrating the Urban Canopy Layer in a Lagrangian Particle Dispersion Model

Stefan Stöckl1, Mathias W. Rotach1, and Natascha Kljun2
Stefan Stöckl et al.
  • 1Department of Atmospheric and Cryospheric Sciences, University of Innsbruck, Innsbruck, Austria (
  • 2Centre for Environmental and Climate Science, Lund University, Lund, Sweden

Traditional Lagrangian particle dispersion models reflect particles at the zero-plane displacement height and therefore cannot properly take near-ground effects into account. In this study, we investigate whether including the urban canopy layer improves the performance of such a Lagrangian particle dispersion model. Here, spatially averaged flow and turbulence profiles throughout the urban canopy are constructed based on data from the literature (mostly from wind tunnel and numerical modeling studies).

We apply a first-order approach to test to what degree the explicit inclusion of the urban canopy changes the simulated concentration distributions. In a comprehensive sensitivity study, we show that most of the parameters introduced to describe the turbulence and flow profiles in the canopy have a relatively minor impact on the dispersion (and hence concentration distribution) – despite their inherent uncertainty. In particular, concentration fields are more sensitive to previously existing parameters of the model. One exception is a parameter describing the mean canopy wind speed profile, to which the model is sensitive.

When compared to data from the BUBBLE tracer experiment, the results show that the inclusion of the urban canopy layer slightly improves the modelled concentration values. The improvement is minor and might likely differ when comparing with other field experiments. However, the key point here is that the increased complexity and added capability of near-ground concentration simulation did not fundamentally change the model performance.

Ultimately, inclusion of the urban canopy layer will allow the model to be used as the dispersion core for an urban footprint model with footprint estimates near the ground.

How to cite: Stöckl, S., Rotach, M. W., and Kljun, N.: Integrating the Urban Canopy Layer in a Lagrangian Particle Dispersion Model, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16119,, 2021.


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