Extending the SBUV polar mesospheric cloud data record with the OMPS NP

DeLand, Matthew T.; Thomas, Gary E.

doi:https://doi.org/10.5194/acp-19-7913-2019

Articles | Volume 19, issue 11

https://doi.org/10.5194/acp-19-7913-2019

© 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-19-7913-2019

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

Articles | Volume 19, issue 11

Research article

|

14 Jun 2019

Research article |

| 14 Jun 2019

Extending the SBUV polar mesospheric cloud data record with the OMPS NP

Matthew T. DeLand and Gary E. Thomas

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Final revised paper (published on 14 Jun 2019)
Preprint (discussion started on 06 Dec 2018)

Interactive discussion

Status: closed

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

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RC1: 'Review on "Extending the SBUV PMC Data Record with OMPS NP" by DeLand and Thomas.', Anonymous Referee #2, 26 Dec 2018
RC2: 'Comment on "Extending the SBUV PMC Record with OMPS NP"', Anonymous Referee #1, 03 Jan 2019
AC1: 'Author Response', Matthew DeLand, 15 Mar 2019

Peer-review completion

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

AR by Matthew DeLand on behalf of the Authors (15 Mar 2019) Author's response Manuscript

ED: Referee Nomination & Report Request started (01 Apr 2019) by Robert Hibbins

RR by Anonymous Referee #2 (15 Apr 2019)

RR by Anonymous Referee #1 (03 May 2019)

Suggestions for revision or reasons for rejection

Review of “Extending the SBUV PMC Data Record with OMPS NP” by DeLand and Thomas [2018].

The reviewer thanks the authors for responding to comments. The reviewer has more comments on these responses before the manuscript can be recommended for publication. Specific comments and technical corrections are below.

Specific Comments:

1. The reviewer thanks the authors for including the requested figure (new Figure 3). Please indicate the year, day and UT of the data shown so that the interested reader can reproduce the figure. At the bottom of p. 6 the authors state the spread of the non-PMC albedo residual values equatorward of 60 degrees. If the authors are implying that this is a statistical uncertainty in the residual PMC brightness at all latitudes, then they should say so explicitly in the manuscript. If that is not what they meant then please explain the significance of this spread in the manuscript. Nevertheless, the reviewer has asked for an estimate of the systematic uncertainty at PMC latitudes (i.e. poleward of 60 degrees) and this is still not provided. This is important for quantitative comparison with other satellite datasets (including SBUV) and different from the threshold shown in Figure 2. It is an estimate of the bias introduced when separating the Rayleigh background from a given observation. Please state and justify this systematic uncertainty as a function of PMC latitude.

2. The reviewer thanks the authors for adding text discussing comparison of their results with other datasets and with model results.
a. There is new text following Figure 6 (line 224) addressing this. On line 235 the authors argue that particle sizes observed by SBUV are greater than 35-40 nm based partly on CIPS results. Hervig and Stevens [2014] calculated SBUV particle radii directly and get this answer for northern hemisphere observations. Is there a reason the authors omitted this SBUV particle size analysis? If not, then please reference the study when discussing particle size.
b. On line 240, do the authors mean Figures 4(b), 5(b), and 6(b) rather than Figures 4(c), 5(c), and 6(c)? Figures 4(b), 5(b), and 6(b) show IWC rather than frequency.
c. Although the comparison with the Stevens et al. [2017] results indicate that IWC is 20-30% greater than OMPS or SBUV, the frequency comparison is much different with the model results approximately ten times larger than the SBUV observations in NH 2009 (4 LT) (see also Schmidt et al., 2018). Since the authors are showing both IWC and frequency in Figures 4, 5 and 6 this should be included in the discussion. Can the authors explain this model/data difference in frequencies? Hervig and Stevens [2014] suggest a bias in the SBUV background subtraction could play a role (see comment #1 and Figure 3) in a reported frequency difference between SOFIE and SBUV. Please comment in the text.

Technical Corrections:

1. The reviewer asked for local times of the observations presented rather than equator-crossing local times. This was done in Deland et al. [2007] (their Figure 2) and Hervig and Stevens [2014] (their Figure 5), which are both cited by the authors. The authors indicate that they do not do this because they want to characterize orbit drift. Please explain how the equator crossing local time better describes the relevant orbit drift as opposed to the local time of the observations.

2. Note on line 114 that the solar zenith angle is the supplement of the scattering angle, not the complement.

3. The reviewer requested clarification on “each instrument” (now on p. 14, line 313) and whether that meant “each SBUV and OMPS instrument”. Although the authors said they revised the text here, the reviewer does not see the changes. Please clarify.

4. In the trend discussion on p. 16 the authors indicate that their definition of “significance” is not as simple as “statistical significance”. However, in the abstract on line 18 they indeed use the term “statistically significant” when discussing trends. Please either modify the abstract or use “statistical significance” in the trend discussion.

5. In the conclusion (now p. 17, line 396) the reviewer requested they use “poleward” instead of “above”. The authors stated they revised the text here but the reviewer does not see this revision. Please edit or explain.

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ED: Publish subject to minor revisions (review by editor) (07 May 2019) by Robert Hibbins

AR by Matthew DeLand on behalf of the Authors (21 May 2019) Author's response Manuscript

ED: Publish as is (23 May 2019) by Robert Hibbins

AR by Matthew DeLand on behalf of the Authors (28 May 2019) Manuscript

Short summary

We have extended our 40-year satellite data record of polar mesospheric cloud (PMC) behavior by adding data from a new instrument. Long-term trends in PMC ice water content derived from this record are smaller since 1998 compared to the first part of our data record. The PMC response to solar activity has decreased in the Northern Hemisphere but increased in the Southern Hemisphere, for reasons that are not understood.