Preprints
https://doi.org/10.5194/acp-2021-461
https://doi.org/10.5194/acp-2021-461

  17 Jun 2021

17 Jun 2021

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

Eastward-propagating planetary wave in the polar middle atmosphere

Liang Tang, Sheng-Yang Gu, and Xian-Kang Dou Liang Tang et al.
  • Electronic Information School, Wuhan University, Wuhan, China

Abstract. We presented the global variations of the eastward propagating wavenumber 1 (E1), 2 (E2), 3 (E3), and 4 (E4) planetary waves (PWs) and their diagnostic results in the polar middle atmosphere, using MERRA-2 temperature and wind datasets in 2019. It is clearly shown that the eastward wave modes exist during winter periods with westward background wind in both hemispheres. The maximum wave amplitudes in the southern hemisphere (SH) are slightly larger and lie lower than those in the northern hemisphere (NH). It is also found that the wave perturbations peak at lower latitudes with smaller amplitude as the wavenumber increases. The period of the E1 mode varies from 3 to 5 days in both hemispheres, while the period of E2 mode is slightly longer in the NH (48 h) than in the SH (40 h). The periods of the E3 are ~30 h in both SH and NH, and the period of E4 is ~24 h. Though the wave periods become shorter as the wavenumber increases, their mean phase speeds are relatively stable, which are ~53, ~58, ~55, and ~52 m/s at 70° latitudes for W1, W2, W3, and W4, respectively. The eastward PWs occur earlier with increasing zonal wavenumber, which agrees well with the seasonal variations of the background zonal wind through the generation of critical layers. Diagnostic analysis also shows that the mean flow instability in the upper stratosphere and upper mesosphere may both contribute to the amplification of the eastward PWs.

Liang Tang et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-461', Anonymous Referee #1, 20 Jul 2021
    • AC1: 'Reply on RC1', Liang Tang, 04 Sep 2021
  • RC2: 'Comment on acp-2021-461', Anonymous Referee #2, 21 Jul 2021
    • AC2: 'Reply on RC2', Liang Tang, 04 Sep 2021

Liang Tang et al.

Liang Tang et al.

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Short summary
Our study is to explore the variation of occurrence date, peak amplitude, and wave period for eastward wave and the role of instability, background wind structure, and critical layer for the eastward wave propagation and amplification.
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