Contribution of Etalon Observation to Earth Rotation Parameters under a New Observation Scenario

Round 1

Reviewer 1 Report

The article is devoted to an important issue – the contribution of more Etalon observations in the new observation scenario to weekly ILRS products. This is quite an interesting task according to the new methods of big data analysis. The authors compare the ILRS products estimated from LAGEOS-only solutions and LAGEOS+Etalon solutions.

Introduction The introduction provides a comprehensive analysis of the study area. The purpose of the study and the content of the sections of the article are described in sufficient detail.

Data and Methods are fully described

Results are described in sufficient detail. Figures and tables allow you to visualize the results of the study

Discussion. The section discusses the results of studies with existing approaches.

Conclusions The conclusions are fully consistent with the study presented in the article. However, the nature of the article is research, it is more expedient to put one point at the end (line 449)

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

This paper entitled “Contribution of Etalon observation to station coordinates, earth rotation parameters and satellite orbit under a new observation scenario” mainly studies the differences/impacts between LAGEOS-only solutions and LAGEOS+Etalon solutions based on a 3-month Etalon tracking campaign in 2019. The paper is not written very well, e.g., the background and relevant former study review, unclear processing methods, low-quality figures, etc. The article lacks innovation in methodologies, but the authors found some improvements to ERPs due to the contribution of more Etalon observations. Here, please add the scientific contributions/significance of the improved ERPs compared to the regular ERPs. Therefore, this paper is not suitable for publication in the current format. Please check carefully before submitting it, and all co-authors have the responsibility to make it of good quality. Here, some open points need to be discussed and improved before publication. Therefore, I suggest rejection or major revision of the manuscript.

Please find below a collection of these points.

1. The title may be changed due to the actual contribution and findings of Etalon observations in the study.

2. Literature review from Line 53-87. Please write it more clearly.

3. Section 2.2, please write the methodology clearly, with exact formulas. What’s new? What are the differences? Or just standard methods used in Bernese?

4. Most of the figures are of low quality. Please keep them in the same format.

5. Supplementary materials? Data availability? I suggest the authors open access to the original data or even the modified Bernese GNSS software used in this research, and then readers can repeat the results.

6. Add the scientific contributions/significance of the improved ERPs compared to the regular ERPs.

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

My comments for Authors:

1. line 108-113, please add more informatioan about novelty of paper.
2. table 1, maybe you could add coordinates of each stations?

In my opinion the paper is good. I accept this version.

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The figures could be further improved!

Author Response

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Author Response File: Author Response.pdf

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

The authors investigate the contribution of Etalon satellites on ILRS products using a 3-month time series. The motivation of the manuscript is clear and useful and interesting work is done. However, I do not feel there is any significant contribution. In past ten years, it has so many similar studies for the combination of LAGEOS and Etalon satellites. The mathematical and physical significance of geodetic parameters usually emerges from long-term time series, especially for ERPs and geocenter coordinates. And the time series had been selected no less than 1-year in a large number of studies as early as 20 years ago. Moreover, the solutions are bound to change when Etalon data is added. The more redundant observations they have, the greater positive contribution they provide. Such conclusion is obvious and verified by many scholars.

1. long term data at least one-year should be performed to investigate the contribution of Etalon satellites on ILRS products.
2. The main contribution and innovation of the manuscript should be pointed out, and the main difference compared with the existing literatures should be also clearly pointed out.
3. The estimation of LOD seems to be wrong. I suggest the authors reexamine your program design and strategy. The values of “LOD” have no change when you add the Etalon data as shown in Table 4 and Table 5. What is the main reason and Why?
4. In line 55 of section 1, please give the full name of “LOD”.
5. In line 95 of section 1, what does “ASC” refer to?
6. In line 110 of section 2.1, I am not sure you adopt the SLR data from EDC, or CDDIS, or both?
7. In line 128 of section 2.1, I suggest replacing Figure 2 with a bar chart.
8. In line 130 of section 2.1, what do the different colored bars in Figure 3 mean?
9. In line 136 of section 2.1 and line 160 of section 2.2, “7-days” -> “7-day”.
10. In line 153 of section 2.1, I suggest replacing Figure 4 with a bar chart.

In line 155 of section 2.2, “LAGEOS-”-> “LAGEOS”.

11. As seen in line 265 of section 3.1 as “In summary: ”, I recommend avoiding colons whenever possible. Please check the others.
12. In Table 4 and Table 5 of section 3.2, please unify the expression of “LOD” and “LoD”. All abbreviations should be defined when they first appear in the text. Please check them.
13. In section 3.5, how about the orbital accuracy of Etalon satellites? As a core factor, why not analyze their orbital accuracy?
14. I suggest unifying the expression of “MJD” and “Day of Year” in your figures.

    15. Many grammatical problems have to be corrected and the whole manuscript should be polished in language.

Reviewer 2 Report

I am willing to continue to review this manuscript, but I believe it needs some work with a better English writer than the authors have achieved. While the spelling is generally correct, the grammar and sentence structure are very tedious to work through. Since this would be a necessary correction for my recommendation to publish in any case, I would prefer to spend my time reading a more refined version.  

A second comment to the authors would be to simplify the discussion of how much data is contributed from each satellite and when. It should not take about two pages to summarize the data that was used, particularly as it is all in the public domain anyway. I don’t think a breakdow by weeks is any help to the discussion. It would be enough to say how much more data was provided during the campaign than nominal, and how much Etalon data was used compared to Lageos-1/2. Some brevity will benefit the authors considerably.  

As I said, I am willing to provide a serious review of the manuscript, but not in its present form.

Reviewer 3 Report

My comments as below:

1. abstract, all acronyms must be explained, e.g. LAGEOS, ILRS, IERS, etc.
2. main body of text, please check if all acronyms are explained if you used their first time in text.
3. last paragraph of chapter 1, please underline your novelty and your contribution in this paper.
4. Figure 1, please also add list of SLR stations in table, it will be better visible.
5. vertical axis into Figures 2-4, what means NPTS? In text I see the word NPs, please explain it.
6. line 155: "LAGEOS-..."? it should be -1/2?
7. line 457-459 (chapter 6) please removed from text.