A new method to detect and classify polar stratospheric nitric acid trihydrate clouds derived from radiative transfer simulations and its first application to airborne infrared limb emission observations

Kalicinsky, Christoph; Griessbach, Sabine; Spang, Reinhold

doi:https://doi.org/10.5194/amt-14-1893-2021

Articles | Volume 14, issue 3

https://doi.org/10.5194/amt-14-1893-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

New developments in atmospheric limb measurements: instruments,...

https://doi.org/10.5194/amt-14-1893-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 14, issue 3

Research article

|

09 Mar 2021

Research article |

| 09 Mar 2021

A new method to detect and classify polar stratospheric nitric acid trihydrate clouds derived from radiative transfer simulations and its first application to airborne infrared limb emission observations

Christoph Kalicinsky, Sabine Griessbach, and Reinhold Spang

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Final revised paper (published on 09 Mar 2021)
Preprint (discussion started on 27 Jul 2020)

Interactive discussion

Status: closed

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

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RC1: 'Referee report', Wolfgang Woiwode, 06 Aug 2020
- AC1: 'Reply to Reviwer 1', Christoph Kalicinsky, 26 Oct 2020
RC2: 'Review of "Radiative transfer simulations and observations of infrared spectra in the presence of polar stratospheric clouds: Detection and discrimination of cloud types" by Kalicinsky et al.', Anonymous Referee #2, 24 Aug 2020
- AC2: 'Reply to Reviewer 2', Christoph Kalicinsky, 26 Oct 2020
RC3: 'review', Anonymous Referee #3, 25 Aug 2020
- AC3: 'Reply to Reviewer 3', Christoph Kalicinsky, 26 Oct 2020

Peer-review completion

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

AR by Christoph Kalicinsky on behalf of the Authors (26 Oct 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (27 Oct 2020) by Miriam Sinnhuber

RR by Wolfgang Woiwode (11 Nov 2020)

Suggestions for revision or reasons for rejection

From my point of view, the authors clearly have improved the manuscript, and I appreciate their efforts very much. I would suggest to consider the following points prior to final publication. Indicated figure numbers and line numbers refer to the manuscript including track changes.

1. Depending on the scope of the paper, a more direct comparison of observed and simulated spectra would be interesting to show to which degree the observations are reproduced from a spectroscopic point of view. However, if the goal is mainly to show that a signature similar to the observed NAT feature can be simulated qualitatively in the considered spectral range to support the proposed size classification, and a quantitative simulation is beyond the scope, the indirect comparison of Figs. 1,5, with Figs. 9f, 12 may be sufficient from my point of view. In this case, this aspect (i.e. best-possible approximation of the observed feature within underlying assumptions) should be mentioned more clearly in the sections 5 and 6.

2. In the discussion section, it should be clarified that the presented qualitative simulations of the NAT feature do not constitute a proof that the spectra attributed to highly aspherical in the Woiwode et al. (2016, 2019) studies can be simulated quantitatively by the proposed method on the basis of spherical particles. From my point of view, the statements at L608-L613 are supported only qualitatively by the presented results and are limited to the spectral range used here. Therefore, I would suggest to clarify these aspects. Regarding L619, I cannot confirm that the shifted NAT feature in the previous study was solely attributed to asphericity (mode radius was also important, see Woiwode et al. (2016), Fig. 12, Fig. B2 and conclusions).

3. I appreciate the information provided by the authors regarding the influence of tropospheric clouds and I agree that the presence/absence of tropospheric clouds will mainly contribute a broadband-component to the spectrum and weaken the amplitude of the NAT feature. Since the scattered tropospheric component of the spectrum also modulates the appearance of the NAT feature to some degree (compare refractive index real part in Fig. 2a), I would suggest to double-check or discuss in more detail whether this aspect could affect the conditions used for size classification.

4. I would encourage to compare the collocated PSC particle observations from the same aircraft (Molleker et al., 2014, Grooß et al., 2014) at least briefly with the presented results in the manuscript.

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RR by Anonymous Referee #2 (18 Nov 2020)

ED: Publish subject to minor revisions (review by editor) (04 Dec 2020) by Miriam Sinnhuber

AR by Christoph Kalicinsky on behalf of the Authors (09 Dec 2020) Author's response Manuscript

ED: Publish as is (18 Dec 2020) by Miriam Sinnhuber

AR by Christoph Kalicinsky on behalf of the Authors (15 Jan 2021)

Short summary

For an airborne viewing geometry, radiative transfer simulations of infrared limb emission spectra in the presence of polar stratospheric clouds – nitric acid trihydrate (NAT), supercooled ternary solution, ice, and mixtures – were used to develop a size-sensitive NAT detection algorithm. Characteristic size-dependent spectral features in the 810–820 cm⁻¹ region were exploited to subgroup the NAT into three size regimes: small NAT (≤ 1.0 μm), medium NAT (1.5–4.0 μm), and large NAT (≥ 3.5 μm).