Preprints
https://doi.org/10.5194/acp-2021-824
https://doi.org/10.5194/acp-2021-824

  26 Oct 2021

26 Oct 2021

Review status: this preprint is currently under review for the journal ACP.

Decay times of atmospheric acoustic-gravity waves after deactivation of wave forcing

Nikolai M. Gavrilov1, Sergey P. Kshevetskii1,2, and Andrey V. Koval1,3 Nikolai M. Gavrilov et al.
  • 1Atmospheric Physics Department, Saint-Petersburg State University, Saint Petersburg, 199034, Russia
  • 2Physics Department, Immanuel Kant Baltic Federal University, Kaliningrad, 236016, Russia
  • 3Meteorological Forecast Department, Russian State Hydro-meteorological University, Saint Petersburg, 192007, Russia

Abstract. High-resolution numerical simulations of non-stationary nonlinear acoustic-gravity waves (AGWs) propagating upwards from surface wave sources are performed for different temporal intervals relative to activation/deactivation times of the wave forcing. After activating surface wave sources, amplitudes of AGW spectral components reach a quasi-stationary state. Then the surface wave forcing is deactivated in the numerical model, and amplitudes of vertically traveling AGW modes quickly decrease at all altitudes due to discontinuations of the upward propagation of wave energy from the wave sources. However, later the standard deviation of residual and secondary wave perturbations experiences slower quasi-exponential decrease. High-resolution simulations allowed, for the first time, estimating the decay times of this wave noise produced by slow residual, quasi-standing and secondary AGW spectral components, which vary between 20 and 100 hrs depending on altitude and the rate of wave source activation/deactivation. The standard deviations of the wave noise are larger for the case of sharp activation/deactivation of the wave forcing compared to the steep processes. These results show that transient wave sources may create long-lived wave perturbations, which can form a background level of wave noise in the atmosphere. This should be taken into account in parameterizations of atmospheric AGW impacts.

Nikolai M. Gavrilov et al.

Status: open (until 07 Dec 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-824', Anonymous Referee #1, 18 Nov 2021 reply
    • AC2: 'Reply on RC1', Nikolai M. Gavrilov, 29 Nov 2021 reply
  • RC2: 'Comment on acp-2021-824', Anonymous Referee #2, 19 Nov 2021 reply
    • AC1: 'Reply on RC2', Nikolai M. Gavrilov, 27 Nov 2021 reply

Nikolai M. Gavrilov et al.

Nikolai M. Gavrilov et al.

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Short summary
High-resolution simulations are used for studying decays of nonlinear atmospheric acoustic-gravity waves (AGWs) after deactivations of the surface wave forcing. The standard deviations of AGW perturbations, after fast dispersions of traveling modes, experience slower exponential decreases. AGW decay times are for the first time estimated, and are 20–100 hr in the stratosphere and mesosphere. This requires accounting slow, quasi-standing and secondary modes in parameterizations of AGW impacts.
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