Evaluation of SCIAMACHY Level-1 data versions using nadir ozone profile retrievals in the period 2003–2011

Shah, Sweta; Tuinder, Olaf N. E.; van Peet, Jacob C. A.; de Laat, Adrianus T. J.; Stammes, Piet

doi:https://doi.org/10.5194/amt-11-2345-2018

Articles | Volume 11, issue 4

https://doi.org/10.5194/amt-11-2345-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/amt-11-2345-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 11, issue 4

Research article

|

25 Apr 2018

Research article |

| 25 Apr 2018

Evaluation of SCIAMACHY Level-1 data versions using nadir ozone profile retrievals in the period 2003–2011

Sweta Shah, Olaf N. E. Tuinder, Jacob C. A. van Peet, Adrianus T. J. de Laat, and Piet Stammes

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Final revised paper (published on 25 Apr 2018)
Preprint (discussion started on 09 Jun 2017)

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'Referee comments and suggestions', Anonymous Referee #1, 04 Jul 2017
- AC1: 'Response 1', Sweta Shah, 24 Nov 2017
- AC4: 'The response and manuscript', Sweta Shah, 25 Nov 2017
RC2: 'Comments', Anonymous Referee #2, 04 Jul 2017
- AC2: 'Response 2', Sweta Shah, 24 Nov 2017
- AC5: 'The response and manuscript', Sweta Shah, 25 Nov 2017
RC3: 'Review of "Nadir ozone profile retrieval from SCIAMACHY and its application to the Antarctic ozone hole in the period 2003-2011"', Anonymous Referee #3, 05 Jul 2017
- AC3: 'Response 3', Sweta Shah, 24 Nov 2017
- AC6: 'The response and manuscript', Sweta Shah, 25 Nov 2017

Peer-review completion

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

AR by Sweta Shah on behalf of the Authors (11 Dec 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (16 Jan 2018) by Pawan K. Bhartia

RR by Anonymous Referee #1 (26 Jan 2018)

Suggestions for revision or reasons for rejection

I. General impression
In comparison with the first submitted version of this manuscript, this second version has much improved in many ways. The title, abstract, research intentions and presentation are clear and the work is well motivated, the scientific language and English formulations have strongly improved, and the unclarities in the original version have mostly been addressed and removed or elucidated. Yet two aspects of the paper might still require minor revision (see specific comments below).

II. Specific comments:
1. This work addresses many aspects of SCIAMACHY L1 data and their evaluation in several ways. This certainly has scientific value, but too much information reduces the overall clarity. I would therefore suggest to leave out section 3 and the right column of Figure 3, and integrate the information on the left column of Figure 3 into section 4.1 (and combine Tables 3 and 4 correspondingly). A separate focus on the 10°N to 10°S L1 version effects on L2 seems somewhat redundant when all versions are compared with ozonesonde measurements on a global scale in a later section.
2. It is unexplained and very confusing that the prior comparison results in terms of median bias are typically much better in the UTLS and below for the prior profiles than for the retrieved profiles! This might be due to the fact that the McPeters-Labow climatology is generated from ozonesonde (and MLS) profiles. In terms of random uncertainty however (i.e. comparison spread) the satellite retrievals might do better than the prior profiles due to their better caption of specific ozone dynamics. It is therefore suggested to either leave out the prior comparison (easy option) or add the comparison spread to the plots and explain the differences between satellite retrieval and prior comparisons bias and spread (scientifically preferred option).

III. Technical corrections:
In the abstract it is not fully clear whether the improvement suggestions made in the last paragraph are there for information only, or have really been tested. Please specify that the latter is true.
Page 1 line 61: When referring to Staehelin, please mention 70 “operational” stations worldwide. There are more stations, but not all provide data all the time.
Page 2 line 100: Remove double brackets around reference.
Section 3 and Figure 4: DFS profiles have little quantitative information if the corresponding layer thicknesses are unknown. Please explicitly refer to level-DFS or layer-DFS in the text and use markers instead of lines in the plot, or convert to DFS/km values for clarity.
Page 12 last paragraph of section 4.2 and Figure 8: “The validation results are clearly less noisy and smoother for the case where the AK was applied to the ozone sondes.” is still rather vague. Please mention explicitly that AK-smoothing of the reference data is performed with the intention to remove the vertical smoothing difference error from the comparison error budget between satellite and ground-based observations. With this explicit formulation, Figure 8 even can be considered superfluous and can be left out of the manuscript, as it contains little information that contributes to the remainder of the discussion.

Referee Report: PDF

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RR by Anonymous Referee #2 (27 Jan 2018)

Suggestions for revision or reasons for rejection

This manuscript is completely different from the previous one. The authors have narrowed down this paper to the evaluation of SCIMACHY L1 data using the validation results of L2 ozone profile with ozonesonde observations. This paper is interesting and helps SCIMACHY users understand the data quality of SCHIMACHY’s ozone profiles. However, this paper still needs some major revisions before publishing in AMT. The details are as follows:
General comments:
• The authors described the measured reflectance spectra with different L1 versions in 2003 and 2009, respectively. It would be a good idea to show the measured reflectance spectra all years from 2003 to 2009. This would tell the readers the time series of degradation and how v8 L1 data improve or reduce the impacts of degradation.
• The authors showed validation results of two V7 versions and V8 version in Section 4.1, validation results of V8 version in Section 4.2 again. I don’t see why there is any need to show validation results in two sections. Why not simply presenting all validation results in one section?
• The figure presentation in this paper could be improved.
Specific comments:
Abstract: please clarify that the stratosphere refers pressures ranging from 100-10 hPa, and the troposphere refers pressures ranging from 1000-100 hPa in the abstract.
Please confirm this number.
Page 6 Line 70 “That means that there is at most one piece of information in the troposphere.” I understand what you meant, but please rephrase it.
Page 7 Line 16. Rephrase “The validation should be done with the sonde profile as it would have been observed by the satellite.”
Figure 2. Please plot all 31 averaging kernels with the corresponding altitudes or pressures.
Figure 3. Please name each panel by letters or numbers. Please change “log Rmeas” to natural log In. The “log” would cause many confusions.
Figure 5: the authors could merge these two figures to one.

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RR by Anonymous Referee #3 (29 Jan 2018)

Suggestions for revision or reasons for rejection

The manuscript “Evaluation of SCIAMACHY Level-1 data versions using nadir ozone profile retrievals in the period 2003-2011” by S. Shah et al. was re-submitted to the AMT after a major revision. The manuscript had been significantly improved. Authors changed the title of the manuscript, which now reflects the content of the study. This study focuses on evaluation of several versions of Level-1 SHIAMACHY nadir data by validating Level 2 ozone profile retrievals against sonde measurements. Based on this results authors recommend to use the latest version 8.0 of Level 1 data with the advanced degradation corrections. In section 5, authors provide suggestions to further improve Level 1 data by retrieving the slit function parameters (like offset, gain, shift and squeeze) and applying an empirical radiometric bias correction.
This study fits well to the scope of the problems discussed in the AMT. I would recommend this manuscript for final publication after minor changes.

Specific comments:

-Figure 4: What exactly are you showing here? Is this a layer DFS? Why would you have larger DFS at the top of the atmosphere, while AKs shown in Fig. 2 clearly indicate a decline in information content above ~1 hPa? Do you show integrated DFS from the bottom to the top? Please, explain that in the text and figure caption.

-Tables 4 and 5: Please, explain how you determined the range and median deviations for the thick layers – Stratosphere [100-10] hPa or Troposphere [1000-100] hPa - shown in the tables. Is it a mean range for the profile comparisons over altitude range 1000-100 hPa? Or do you compare ozone columns directly?

-Tables 5 and 3: Why DFSs in Table 5 are much smaller than in Table 3?

-Page 7, lines 20-25: As you noticed in the text, the nadir AKs have very complicated shapes with long tails that extend far away from the nominal layer. However, sonde measurements typically stop around 25-30 km. What do you use above that? Do you assume that (X_sonde-X_a) is equal to 0 at altitudes above 30 km? Please, explain your approach in the text.

-Page 12 lines 37-43: I suggest to move this section upfront and put it right after the discussion of the smoothing procedure on Page 7. Figure 8 should also appear before figures 6 and 7.

-Page 14, line 89: It is stated that “… v8 dataset gives the most smooth ozone profiles”. Do you mean vertically “smooth” profiles? I believe there is no discussion about “smoothness” of the ozone retrievals in sect. 3 or sect. 4. Can you please explain what you mean by “the most smooth O3 profiles”?

-Figure 11. It is almost impossible to see values for 2011. I suggest to change a color scale for this figure.

Technical comments:

-Page 1, line 9: remove a bracket “)” after “Algorithm)”;
-Page 1. Line 6: spell out SCHIAMACHY when you use it for the first time;
-Page 1, line 52-54: This sentence needs a revision. A possible suggestion would be: “Long-term monitoring of the ozone layer is primarily based on analysis of total ozone time series from global satellite measurements.”
-Page 2, lines 1-17: all acronyms should be explained: MLS, MIPAS, OSIRIS, OMPS, ACE, IR, TES, OMI etc.
-Page 12, line 31: remove a bracket after “to -45%)”.

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ED: Publish subject to minor revisions (review by editor) (06 Feb 2018) by Pawan K. Bhartia

AR by Sweta Shah on behalf of the Authors (22 Mar 2018) Manuscript

ED: Publish as is (05 Apr 2018) by Pawan K. Bhartia

AR by Sweta Shah on behalf of the Authors (05 Apr 2018)

Short summary

The depletion of the Antarctic ozone layer and its changing vertical distribution have been monitored closely by satellites in the past decades ever since the Antarctic ozone hole was discovered in the 1980s. We study and assess the quality of the ozone profiles using SCIAMACHY ultraviolet data and compare them against the ozone sondes.