EGU21-14030, updated on 04 Mar 2021
https://doi.org/10.5194/egusphere-egu21-14030
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Small-scale gravity waves influence on an idealized quasi-biennial oscillation

Xavier Chartrand1, Louis-Philippe Nadeau, and Antoine Venaille2
Xavier Chartrand et al.
  • 1Institut des sciences de la mer de Rimouski, Université du Québec à Rimouski, Rimouski, Canada (xavier.chartrand@uqar.ca)
  • 2Physics Laboratory, ENS de Lyon, Lyon, France

Recent observations from the ERA5 reanalysis have revealed wave contributions from a wide range of spatial and temporal scales to the momentum budget of the equatorial stratosphere. Although it is generally accepted that the wave forcing at the equator drives the quasi-biennial oscillation (QBO) of equatorial winds, the individual contribution of each type of wave is still poorly understood. Here, we seek to disentangle the role of different wave types in the momentum budget of an idealized stratosphere. Numerical simulations with increasing spatial resolution are used to infer the sensitivity of the wave spectrum and mean flow oscillation to resolved instabilities. At higher resolution, Kelvin-Helmholtz generated small-scale gravity waves are combined to the background low frequency wave forcing and accelerate the period of mean-flow reversals due to an increased momentum transfer from the wave to the mean flow. This mechanism is confirmed using a simplified one-dimensional model for which the wave properties are specified.

How to cite: Chartrand, X., Nadeau, L.-P., and Venaille, A.: Small-scale gravity waves influence on an idealized quasi-biennial oscillation, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14030, https://doi.org/10.5194/egusphere-egu21-14030, 2021.

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