First measurements of tides in the stratosphere and lower mesosphere by ground-based Doppler microwave wind radiometry

Hagen, Jonas; Hocke, Klemens; Stober, Gunter; Pfreundschuh, Simon; Murk, Axel; Kämpfer, Niklaus

doi:https://doi.org/10.5194/acp-20-2367-2020

Articles | Volume 20, issue 4

https://doi.org/10.5194/acp-20-2367-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/acp-20-2367-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 20, issue 4

Research article

|

28 Feb 2020

Research article |

| 28 Feb 2020

First measurements of tides in the stratosphere and lower mesosphere by ground-based Doppler microwave wind radiometry

Jonas Hagen, Klemens Hocke, Gunter Stober, Simon Pfreundschuh, Axel Murk, and Niklaus Kämpfer

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Final revised paper (published on 28 Feb 2020)
Preprint (discussion started on 02 Oct 2019)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC1: 'Review of acp-2019-870', Anonymous Referee #1, 11 Oct 2019
RC2: 'Referee comments', Anonymous Referee #2, 18 Oct 2019
AC1: 'Author comments', Jonas Hagen, 19 Dec 2019

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Jonas Hagen on behalf of the Authors (19 Dec 2019) Author's response Manuscript

ED: Referee Nomination & Report Request started (09 Jan 2020) by Farahnaz Khosrawi

RR by Anonymous Referee #2 (20 Jan 2020)

RR by Anonymous Referee #1 (21 Jan 2020)

Suggestions for revision or reasons for rejection

The authors did a good job responding to the points raised in my earlier review. I only have a few additional minor comments.
My page and line numbers refer to the version of the paper with changes highlighted.

Page 1, bottom line: “transportation” -> “transport”

Page 2, line 14: “overpass each location on earth at two local times specific to this location“

This is a bit misleading, because the measurements from a sun-synchronous platform are all made at the same local time (for a given latitude). So, the local time is not really specific to this location. For latitudes between about 60 S and 60 N the local time of the measurements is within 1 hour of the local time of the equator crossing.

Page 2, line 15: „The global coverage nevertheless enables tidal studies on shorter timescales also for instruments on these satellites“

This is also a bit misleading, because it’s only true for high latitudes, where the satellite „flies“ through different local times quickly.

Page 2, line 28: „This leaves reanalyses data“ -> „This leaves reanalysis data“

Page 2, line 34: „become more“ -> „became more“

Page 4, line 26: „The most important to us is“

Something is missing here, i.e. the subject of the sentence.

Page 5, line 20: „.. we apply the same composition“

„Composition“ may be misleading here. I suggest using „data treatment“, but leave it to the authors to decide.

Page 6, line 2: „compose“

Same comment as above. I’m not sure all readers will interpret this correctly.

Page 8, line 28: „westwards observation direction“ -> „westward observation direction“

Page 9, line 9: „lower most“ -> „lowermost“

Page 9, line 23: „A possible source of this structure is the mixing of different tidal waves with different vertical wavelengths or propagation directions.“

Could this also be a retrieval artifact? The vertical structure reminds me of oscillations often occurring in profile retrievals.

Page 12, line 9: „This indicates that the coherence time of short timescale disturbances of the diurnal tide might actually be longer than the reanalysis predicts.“

It may also indicate that some of the variability seen in the measured data is not real, right? This possibility should also be mentioned/discussed.

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ED: Publish subject to minor revisions (review by editor) (21 Jan 2020) by Farahnaz Khosrawi

AR by Jonas Hagen on behalf of the Authors (23 Jan 2020) Author's response Manuscript

ED: Publish subject to technical corrections (24 Jan 2020) by Farahnaz Khosrawi

AR by Jonas Hagen on behalf of the Authors (27 Jan 2020) Author's response Manuscript

Short summary

The middle atmosphere (30 to 70 km altitude) is stratified and, despite very strong horizontal winds, there is less mixing between the horizontal layers. An important driver for the energy exchange between the layers in this regime is atmospheric tides, which are waves that are driven by the diurnal cycle of solar heating. We measure these tides in the wind field for the first time using a ground-based passive instrument. Ultimately, such measurements could be used to improve atmospheric models.