EGU23-1251
https://doi.org/10.5194/egusphere-egu23-1251
EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Towards an implementation of topography in a next-generation gravity-wave parameterisation

Ulrich Achatz, Ray Chew, and Stamen Dolaptchiev
Ulrich Achatz et al.
  • Goethe-Universität Frankfurt/Main, Institut für Atmosphäre und Umwelt, Geowissenschaften/Geographie, Frankfurt/Main, Germany (achatz@iau.uni-frankfurt.de)

The Multi-Scale Gravity Wave Model (MS-GWaM) uses raytracing-based modelling that supports transient gravity-wave parametrisation. The state-of-the-art implementation of MS-GWaM in the upper-atmosphere ICON model solves the raytracing equations in three dimensions and accounts for background (non-orographic) and convective gravity-wave sources. Our work extends the capabilities of MS-GWaM to include orography gravity-wave sources, and we present methods and preliminary results towards this goal. Specifically, we first determine the spectral representation of the topography in each ICON grid cell via Fourier fitting. We then apply linear theory to obtain a representation of the bottom boundary for the raytracer. Finally, the bottom boundary serves as an initial condition for the raytracer-based parametrisation of orographic gravity waves. Preliminary results indicate that a judicious setup of this bottom boundary allows for an optimal tradeoff between computational efficiency and a sufficiently accurate representation of the underlying topography.

How to cite: Achatz, U., Chew, R., and Dolaptchiev, S.: Towards an implementation of topography in a next-generation gravity-wave parameterisation, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-1251, https://doi.org/10.5194/egusphere-egu23-1251, 2023.