EGU22-3214
https://doi.org/10.5194/egusphere-egu22-3214
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Inertia-gravity wave diffusion by geostrophic turbulence: the impact of flow time dependence

Michael Cox, Jacques Vanneste, and Hossein Kafiabad
Michael Cox et al.
  • University of Edinburgh, School of Mathematics, Applied Mathematics, United Kingdom of Great Britain – England, Scotland, Wales (michael.cox@ed.ac.uk)

The scattering of short inertia-gravity waves by large-scale geostrophic turbulence in the atmosphere and ocean can be described as a diffusion of wave action in wavenumber space. When the time dependence of the turbulent flow is neglected, waves conserve their frequency, which restricts the diffusion of energy to the constant-frequency cone. We relax the assumption of time independence and consider scattering by a flow that evolves slowly compared with the wave periods, consistent with a small Rossby number. The weak diffusion across the constant-frequency cone introduced by time dependence leads to a stationary energy spectrum that remains localised around the cone (specifically decaying as 1/σ5 with σ the angular deviation from the cone) corresponding to a small frequency broadening. We contrast our results with unbounded frequency broadening that arises for surface- or shallow-water waves.

How to cite: Cox, M., Vanneste, J., and Kafiabad, H.: Inertia-gravity wave diffusion by geostrophic turbulence: the impact of flow time dependence, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3214, https://doi.org/10.5194/egusphere-egu22-3214, 2022.

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