Model results of OH airglow considering four different wavelength regions to derive night-time atomic oxygen and atomic hydrogen  in the mesopause region

Fytterer, Tilo; von Savigny, Christian; Mlynczak, Martin; Sinnhuber, Miriam

doi:https://doi.org/10.5194/acp-19-1835-2019

Articles | Volume 19, issue 3

https://doi.org/10.5194/acp-19-1835-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

Layered phenomena in the mesopause region (ACP/AMT inter-journal...

https://doi.org/10.5194/acp-19-1835-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 19, issue 3

Research article

|

12 Feb 2019

Research article |

| 12 Feb 2019

Model results of OH airglow considering four different wavelength regions to derive night-time atomic oxygen and atomic hydrogen in the mesopause region

Tilo Fytterer, Christian von Savigny, Martin Mlynczak, and Miriam Sinnhuber

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Final revised paper (published on 12 Feb 2019)
Preprint (discussion started on 06 Aug 2018)

Interactive discussion

Status: closed

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

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RC1: 'review of manuscript', Anonymous Referee #1, 31 Aug 2018
- AC1: 'Response to Referee #1', Tilo Fytterer, 12 Nov 2018
RC2: 'Review for New insights into OH airglow modelling to derive night-time atomic oxygen and atomic hydrogen in the mesopause region', Anonymous Referee #2, 03 Sep 2018
- AC2: 'Response to Referee #2', Tilo Fytterer, 12 Nov 2018

Peer-review completion

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

AR by Tilo Fytterer on behalf of the Authors (13 Nov 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (23 Nov 2018) by William Ward

RR by Anonymous Referee #1 (04 Dec 2018)

RR by Anonymous Referee #2 (18 Dec 2018)

Suggestions for revision or reasons for rejection

I have read over your replies. Thank you for making changes to the manuscript. I just have two minor revisions that still need to be addressed.

General Comments:
1. Kalogerakis et al. (2016) only reported that OH(v=9)+O(3P)→OH(v=3)+O(1D) is an important deactivation channel of OH(v=9)+O(3P)→products. They did not provide any rate or branching ratio of the channel. To our understanding, “important” means “not negligible” but it does not mean “dominating”. Thus, we assumed that OH(v=9)+O(3P)→OH(v=3)+O(1D) has to occur but this channel is not necessarily the fastest deactivation path of OH(v=9)+O(3P).
This was stated in the text (l. 490-493):
“However, not much is known about the individual branching ratios of R11 except that
OH(v=9)+O(3P)→OH(v=3)+O(1D) is an important deactivation channel but not necessarily the dominating one (Kalogerakis et al., 2016).”
…
Furthermore, we have to emphasize that, at least to our knowledge, the rates and deactivation schemes applied in the OH model are not in conflict with ANY laboratory measurements but partly disagree with other model studies.

Kalogerakis et al. (2016) measured the rate coefficient of the OH(v=9)+O(3P)→OH(v=3)+O(1D) pathway. Accounting for mesospheric temperatures, the authors suggested a rate of (2.3+/1)e-10 cm3/sec. Your results suggest, for the same pathway, a rate coefficient 0.2 * 2.3e-10 cm3/sec, which is 4.6e-9 cm3/sec, about 3 times lower than the lower bound suggested by Kalogerakis et al. (2016). Whether the reaction is the dominating one or not, the rate coefficient you use for this pathway still does not agree with laboratory results.
In general, many O retrieval studies which use OH models only need to consider OH(v=9) and/or OH(v=8) and therefore, state to state pathways coupling higher and lower levels do not need to be considered carefully. Because you are fitting four bands and require detailed description of OH(v=3-9), these state to state pathways become very important. Currently your OH model disagrees with laboratory measurements, so a sentence in the conclusion and abstract should be added as a disclaimer noting the differences.

2. "Figure 6 displays the vertical profiles of [O(3P)] and [H] obtained by the Best fit model in comparison with the results derived from SABER OH(9-7)+OH(8-6) VER only (Mlynczak et al., 2018). The [O(3P)] profiles seen in Fig. 6a agree below 85 km but the Best fit model shows gradually larger values in the altitude region above. These larger values are caused by the different deactivation rates and schemes of OH(v)+O(3P), agreeing with general pattern reported in Panka et al. (2018). We have to point out that other studies (e.g. von Savigny and Lednyts’kyy, 2013) observed a pronounced [O(3P)] maximum of about 81011 cm-3 at 95 km."

It is clear in Figure 6 that your O begins to gradually increase in the upper altitudes. In a recent paper by Zhu & Kaufmann et al (2018), the authors show that O retrievals by Mlynczak et al. (2018), Panka et al. (2018), and Zhu and Kaufmann (2018) all show O densities which peak around 95 km (see Figures 2 and 3). I am confused by the statement where you report that your O follows the general pattern of Panka et al. (2018) as this increasing pattern is not shown in Panka et al. (2018) or Zhu and Kaufmann (2018). Please remove this sentence or clarify your meaning.

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ED: Publish subject to minor revisions (review by editor) (05 Jan 2019) by William Ward

AR by Tilo Fytterer on behalf of the Authors (14 Jan 2019) Author's response Manuscript

ED: Publish as is (17 Jan 2019) by William Ward

AR by Tilo Fytterer on behalf of the Authors (26 Jan 2019) Manuscript

Short summary

A model was developed to derive night-time atomic oxygen (O(³P)) and atomic hydrogen (H) from satellite observations in the altitude region between 75 km and 100 km. Comparisons between the best-fit model and the measurements suggest that chemical reactions involving O₂ and O(³P) might occur differently than is usually assumed in literature. This considerably affects the derived abundances of O(³P) and H, which in turn might influence air temperature and winds of the whole atmosphere.