Stable Regional Reference Frame for Reclaimed Land Subsidence Study in East China
Round 1
Reviewer 1 Report
This paper presents the contributions of stable regional TRF to land subsidence study. This work is interesting and valuable. However, there are a lot of spelling and grammar mistakes. Some sentences are very difficult to understand. A native speaker is needed to polish the language.
Major issues are as follows:
1) L108, CMEs are removed from the station coordinates in both SHRRF and ITRF14? If CMEs are not removed from station coordinates in ITRF14, I do not think the lower ERMSE and SRMSE (in Figures 5 and 6), and less scatter LGXC (in Figure 9) are meaningful. Authors should provide more details about the processing of CME.
2) L173, the reference stations of SHRRF are very confused. As a regional TRF, why it comprises of 37 global ITRF stations?
3) Figure 2 can be merged with Figure 3.
3) L185, what do the transformation parameters of ‘ITRF14’ in red and ‘SHRRF’ in blue mean? Which stations are used to calculate these transformation parameters? And which TRF are these transformation parameters relative to? Moreover, in L176, the authors mention that “To evaluate the stability of SHRRF, we analyze the consistency of time series of the origin and scale parameters between SHRRF and ITRF14”, but why there are two lines shown in Figure 4. It is very confusing.
4) L190, “the differences between the time series of the origin translations and the scale factor under different frames are not significant, with average standard deviations of 0.02, 0.01, and 0.1 m for the translations in X, Y, and Z, respectively, and 4 ppb for the scale factor”. I do not think the translation and scale are not significant with such large STDs.
5) L331, Figure 10 is interesting. However, the corresponding results in ITRF2014 should be provided and compared. If three SP observations in SHRRF fit the model much better than those in ITRF14, the results would be more convinced.
There are a lot of language mistakes and typos. I just list some of them as follows:
1) L40-L45, syntax and vocabulary should be polished
2) L52, “detailed study” is not a proper expression
3) L97, “Spatial map showing the distribution of SHCORS stations” should be “Station distribution of SHCORS stations”
4) L154, L173, L348, L354…… “ITFR14” should be “ITRF14”
5) L186, delete “Distribution plot”
6) L276, “as fellow” should be “as follows:”
Author Response
We would like to thanks the referee for the valuable suggestions and comments. In the following we reply to each of the referee’s comments (lines start with “Response”).
Point 1: L108, CMEs are removed from the station coordinates in both SHRRF and ITRF14? If CMEs are not removed from station coordinates in ITRF14, I do not think the lower ERMSE and SRMSE (in Figures 5 and 6), and less scatter LGXC (in Figure 9) are meaningful. Authors should provide more details about the processing of CME.
Response 1: CMEs are removed from the station coordinates in both SHRRF and ITRF14. We added the processing details of CME in the text. Principal components and corresponding spatial eigenvectors were calculated based on the continuous coordinate time series matrix. The first principal components of the north, east and vertical components were analyzed as the common-mode errors, which were then subtracted from the station coordinates during the second time series analysis.
Point 2: L173, the reference stations of SHRRF are very confused. As a regional TRF, why it comprises of 37 global ITRF stations?
Response 2: The SHRRF is referred to as the regional realization of ITRF. We added local sites to the core station network to remedy the geometrical sparsity of ITRF14 in China and surrounding regions, that is why the SHRRF comprises of 37 global ITRF stations
Point 3: Figure 2 can be merged with Figure 3.
Response 3: We have merged Figure 2 and Figure 3.
Point 4:L185, what do the transformation parameters of ‘ITRF14’ in red and ‘SHRRF’ in blue mean? Which stations are used to calculate these transformation parameters? And which TRF are these transformation parameters relative to? Moreover, in L176, the authors mention that “To evaluate the stability of SHRRF, we analyze the consistency of time series of the origin and scale parameters between SHRRF and ITRF14”, but why there are two lines shown in Figure 4. It is very confusing.
Response 4: We first merged the loose solutions of the regional subnet into the loose solution of the global network. Then the combined loosely constrained daily global solutions were aligned to the ITRF14 and SHRRF by seven frame parameters of Helmert transformation, respectively. The red/blue dots in Figure 4 represent the conversion parameters between the combined loosely solutions and ITRF14/SHREF.
Point 5:L190, “the differences between the time series of the origin translations and the scale factor under different frames are not significant, with average standard deviations of 0.02, 0.01, and 0.1 m for the translations in X, Y, and Z, respectively, and 4 ppb for the scale factor”. I do not think the translation and scale are not significant with such large STDs.
Response 5: We try to use this statement to indicate that the time series different between of transformation parameters under SHRF and ITRF14 is small. We have revised the description in the manuscript.
Point 6: L331, Figure 10 is interesting. However, the corresponding results in ITRF2014 should be provided and compared. If three SP observations in SHRRF fit the model much better than those in ITRF14, the results would be more convinced.
Response 6: According to your suggestions, we have calculated the standard deviation between the result of SP stations and the model under different frames, and listed it in Table 3. As shown in Table 3, the deviations of all the SP stations under ITRF14 are greater than SHRRF.
Point 7:There are a lot of language mistakes and typos. I just list some of them as follows:
1) L40-L45, syntax and vocabulary should be polished
2) L52, “detailed study” is not a proper expression
3) L97, “Spatial map showing the distribution of SHCORS stations” should be “Station distribution of SHCORS stations”
4) L154, L173, L348, L354…… “ITFR14” should be “ITRF14”
5) L186, delete “Distribution plot”
6) L276, “as fellow” should be “as follows:”
Response 7: We have corrected all the language mistakes and typos that you pointed out. We have also invited a native English speaker to polish the language. The supporting documents are attached.
Author Response File: 
Author Response.docx
Reviewer 2 Report
It is an interesting work in which unfortunately individual parts of the text, and especially a temporal consolidation settlement model of the reclaimed soil under self-weight has been described too briefly and not clearly enough (chapter 4, especially 4.1 and 4.2). Therefore, the article returns to serious refinement so that it could be published in Remote Sensing without any restrictions.
In addition, other deficiencies were observed which are listed chronologically and should be corrected:
1) On page 2, line 69 it says: "The station SHJS has been moved to JSXC, and SSJG has been renamed SJGN since 2012.“ (as well as on page 3, lines 98-99). Can you briefly say why was it done?
2) The aligning procedure of combined loosely constrained solutions to ITRF14 should be shown in more detail than what is written on page 3, lines 100-111 (not all readers are experts in that area).
3) There are a lot of typographical errors, especially in and around formulas (e.g., equation 10, then page 4, line 122, 124, 126, page 5, line 155, ..., that need to be corrected. Matrices in vectors are usually written bold.
4) References should be cited wherever necessary in the text (e.g., page 5, line 150).
5) Figure 2 should be moved backwards (certainly behind Table 2) and merged with Figure 3 (in a single Figure 2) with a color change for 9 IGS stations. At the same time, you should take care of the numbering of the pictures in the rest of the article.
6) In several places in the article, a space is missing after the description of the images (e.g., page 8, line 222, page 9, line 251, page 12, line 334, ...).
7) On page 9, line 255, there is incomprehensible information: (31.7 + 11.1 ≈ 33.6 mm/year)? It needs to be corrected or explained.
8) Equation (11) on page 10 should be better explained (lines 277-280) with reference to the literature used and connection to equation (12).
9) On page 11, line 307, the Levenberg-Marquardt method is mentioned. It would be good to briefly describe it and list the necessary literature.
10) What is meant by the slightly strange term "it is not adequately perfect" (page 13, lines 356-357)?
11) It is usual to write in an indefinite form, and not as, for example, it is written in the first sentence of the Abstract: "We implemented ...". It is better to say: "In this paper ... has been implemented".
Author Response
We would like to thanks the referee for the valuable suggestions and comments. In the following we reply to each of the referee’s comments (lines start with “Response”).
Point 1: It is an interesting work in which unfortunately individual parts of the text, and especially a temporal consolidation settlement model of the reclaimed soil under self-weight has been described too briefly and not clearly enough (chapter 4, especially 4.1 and 4.2). Therefore, the article returns to serious refinement so that it could be published in Remote Sensing without any restrictions.
Response 1: We have added more details of the temporal consolidation settlement model of the reclaimed soil under self-weight.
Point 2: On page 2, line 69 it says: "The station SHJS has been moved to JSXC, and SSJG has been renamed SJGN since 2012.“ (as well as on page 3, lines 98-99). Can you briefly say why was it done?
Response 2: SHCORS belongs to Shanghai Surveying and Mapping Institute. In order to improve the qualities of SHCORS, they made these changes in 2012. We get this information from their records. SHJS and SSJG were reconstructed at another location and named JSXC and SSGN, respectively.
Point3: The aligning procedure of combined loosely constrained solutions to ITRF14 should be shown in more detail than what is written on page 3, lines 100-111 (not all readers are experts in that area).
Response 3: More details about the aligning procedure of combined loosely constrained solutions to ITRF14 have been added in page 3.
Point4: There are a lot of typographical errors, especially in and around formulas (e.g., equation 10, then page 4, line 122, 124, 126, page 5, line 155, ..., that need to be corrected. Matrices in vectors are usually written bold.
Response 4: We have corrected the typographical errors and changed the vectors in bold.
Point 5: References should be cited wherever necessary in the text (e.g., page 5, line 150).
Response 5: We have added necessary references in the text.
Point 6: Figure 2 should be moved backwards (certainly behind Table 2) and merged with Figure 3 (in a single Figure 2) with a color change for 9 IGS stations. At the same time, you should take care of the numbering of the pictures in the rest of the article.
Response 6: We have merged Figure 2 and Figure 3 into the new Figure 2, and changed the color for the 9 IGS stations. The numbers of the pictures in the rest of the article been changed accordingly.
Point 7: In several places in the article, a space is missing after the description of the images (e.g., page 8, line 222, page 9, line 251, page 12, line 334, ...).
Response 7: All the missing spaces after the description of the images have been added.
Point 8: On page 9, line 255, there is incomprehensible information: (31.7 + 11.1 ≈ 33.6 mm/year)? It needs to be corrected or explained.
Response 8: The horizontal velocity here refers to vector sum of the average of the east and north components, i.e., sqrt(31.7^2+11.1^2) ≈ 33.6. We revised the text accordingly.
Point 9: Equation (11) on page 10 should be better explained (lines 277-280) with reference to the literature used and connection to equation (12).
Response 9: We have explained Equation (11) in details. Please see page 13. In page 15, we have also explained the relation between equation (11) and (12).
Point 10: On page 11, line 307, the Levenberg-Marquardt method is mentioned. It would be good to briefly describe it and list the necessary literature.
Response 10: The LM algorithm is an improved algorithm of least squares, which is a nonlinear regression analysis between Newton iterative method and gradient descent method. We have added more details about the LM algorithm and two literatures to the manuscript.
Point 11: What is meant by the slightly strange term "it is not adequately perfect" (page 13, lines 356-357)?
Response 11: This means that SHRRF still has some disadvantages which need to be improved. In addition, as suggested by another reviewer, we moved this paragraph to chapter 3.1, and changed this sentence.
Point 12: It is usual to write in an indefinite form, and not as, for example, it is written in the first sentence of the Abstract: "We implemented ...". It is better to say: "In this paper ... has been implemented".
Response 12: We have changed the "We implemented ..." into "In this paper ... has been implemented".
Author Response File: Author Response.docx
Reviewer 3 Report
Review
stable regional reference frame for reclaimed land subsidence study in east china
This article introduces the SHRRF, a regional reference frame in shanghai and compares it with the ITRF14. It is applied to a consolidation settlement model in a last section. Globally, the article is interesting and suits the special issue well. It is short, which is OK and I appreciated it. I have some comments that would necessitate a major revision.
General comments:
Although the article is well written, the “red line” of the article is not clear and should be improved directly in the introduction. I thought it would “only” be about a regional reference frame as stated but it is applied to a very interesting case study, that should be the focus of the article (i.e. regarding the topic of the special issue), as indicated in the abstract. To my point of view, the abstract and the introduction should be inline and for that, slightly more literature is needed (the authors could used for instance the introduction of section 4 and put it in a more general framework). For readers that are not familiar with that topic, it would be interesting to add more information. To that aim, I would like to have comments in section 4 about the implications of the number you give. There is just one sentence in the conclusion about that “l369). I expect more comments to understand the meaning of this study.
I would suggest to reorganize the paper to make the focus on section 4 clearer, or to make a whole section “applications” that would include for instance section 3.3, which is more an application than a stability analysis. The very important discussion about the periodicity (figure 4) is let to one sentence in the conclusion, I would expect a little bit more to be convinced. More generally, I felt frustrated to have to wait for the conclusion to get some explanations. For such a short paper, it could be worth putting the explanations directly in the text.
Specific comments (unsorted):
There are some typos that need to be addressed in the next iteration, for instance with the equations that are not correctly displayed (probably a problem after building the pdf), spaces are missing or should be deleted (for instance 1.5mm or 1.5 mm) etc. Figure 2 and 3 could be slightly improved (some stations name are overlapping) although it is not that important.
Regarding the figures: could you please give as mentioned more information about the periodic trend (figure 4).
Figure 5: why this offset? Why is the scatter higher?
Please avoid “clear” “it is obvious” etc. For me, it was not. For instance in l324-325: could you provide more information? It is not “obvious” where to see the phases. Are there comparison with other studies?
What is meant with “self weight”?
I would not write “using time series analysis” l103. Delete. Reference 23 is not adequate and general enough. I would expect a text book, for instance Montillet geodetic time series analysis in earth sciences
l128-129: I don’t understand what you mean here under “10 equal weight – 90% relative weight”: why?
L194 season → seasonal
l215 “most of the solutions”, please be more specific, how many?
L222 a figure does not “demonstrate” something to my point of view. Shows?
L228 “affected by more local reasons”: please explain what you meanings
Section 3.3: please provide the up component, even if it is worthier.
Author Response
We would like to thanks the referee for the valuable suggestions and comments. In the following we reply to each of the referee’s comments (lines start with “Response”).
Point 1: General comments:
Although the article is well written, the “red line” of the article is not clear and should be improved directly in the introduction. I thought it would “only” be about a regional reference frame as stated but it is applied to a very interesting case study, that should be the focus of the article (i.e. regarding the topic of the special issue), as indicated in the abstract. To my point of view, the abstract and the introduction should be inline and for that, slightly more literature is needed (the authors could used for instance the introduction of section 4 and put it in a more general framework). For readers that are not familiar with that topic, it would be interesting to add more information.
Response 1: We have moved part of section 4 into the “introduction” and revised the text accordingly, e.g., we have cited more related literature on the reclaimed land studies.
Point 2: To that aim, I would like to have comments in section 4 about the implications of the number you give. There is just one sentence in the conclusion about that “l369). I expect more comments to understand the meaning of this study. I would suggest to reorganize the paper to make the focus on section 4 clearer, or to make a whole section “applications” that would include for instance section 3.3, which is more an application than a stability analysis. The very important discussion about the periodicity (figure 4) is let to one sentence in the conclusion, I would expect a little bit more to be convinced. More generally, I felt frustrated to have to wait for the conclusion to get some explanations. For such a short paper, it could be worth putting the explanations directly in the text.
Response 2: We have moved section 3.3 and section 4 to a new section “Applications” as suggested. The explanations have been added directly to the text. The discussion about the periodicity (figure 4) has been moved to section 3.1.
Point 3: There are some typos that need to be addressed in the next iteration, for instance with the equations that are not correctly displayed (probably a problem after building the pdf), spaces are missing or should be deleted (for instance 1.5mm or 1.5 mm) etc. Figure 2 and 3 could be slightly improved (some stations name are overlapping) although it is not that important.
Response 3: We have checked the whole manuscript carefully to remove the typos. To make the draft more concise, we have merged the original Figure 2 and Figure 3 to make a new Figure 2, and re-plotted the figure to avoid station names overlapping.
Point 4: Regarding the figures: could you please give as mentioned more information about the periodic trend (figure 4).
Response 4: We have added more information about the periodic trend in figure 4. As illustrated in response 2, some of the explanation comes from the conclusion. The periodic trend may be due to the “network effect”, which implies the existence of residual loading effect.
Point 5: Figure 5: why this offset? Why is the scatter higher?
Response 5: In figure 5, under ITRF14, the RMSE of SHCORS is higher than that of SHRRF at most epoch, which is due to the addition of high-precision local sites to the constrained sites during the minimum constraint process. The regional realization of ITRF with sufficient local coverage can significantly improve the accuracy of local solutions.
Point 6: Please avoid “clear” “it is obvious” etc. For me, it was not. For instance in L324-325: could you provide more information? It is not “obvious” where to see the phases. Are there comparison with other studies?
Response 6: We have revised the sentences to avoid usage of “clear” and “it is obvious”, and added more explanations of the Consolidation Settlement Model. We have compared our result t with the studies of Zhao Q (2015). and Yang P (2008). etc.
Point 7: What is meant with “self-weight”?
Response 7: Self-weight refers to only considering the influence of the gravity of the backfill soil itself, ignoring other loads, such as the role of the building loading, underground water pumping, et al. We have added this explanation to the manuscript.
Point 8: I would not write “using time series analysis” L103. Delete. Reference 23 is not adequate and general enough. I would expect a text book, for instance Montillet geodetic time series analysis in earth sciences
Response 8: We have removed “using time series analysis” and change reference 23 to a text book as you suggested.
Point 9:l128-129: I don’t understand what you mean here under “10 equal weight – 90% relative weight”: why?
Response 9: This means that the weights of 10% of the sites is unchanged while re-weighted for 90% of the sites based on residuals. This procedure has been repeated for several times until the solution is converged. According to our data processing experience, it is better to get the optimal solution for all station coordinates after 3-4 iterations.
Point 10:L194 season → seasonal
L215 “most of the solutions”, please be more specific, how many?
L222 a figure does not “demonstrate” something to my point of view. Shows?
Response 10: We have changed “season” to “seasonal”.
Almost 97% of solutions differed by less than 5 mm.
We have changed “demonstrate” to “shows”.
Point 11:L228 “affected by more local reasons”: please explain what you meanings
Response 11: The station coordinate in the vertical direction may be affected by more local reasons, such as the human activities, regional groundwater and surface water quality migration, etc. We have added these explanations to the text.
Point 12:Section 3.3: please provide the up component, even if it is worthier.
Response 12: We have provided the up component.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
This manuscript can be accepted in present form
Author Response
We thank you again for your valuable suggestions and comments, which helped a lot to improve the manuscript.
Reviewer 2 Report
I am satisfied with the way the corrections of my comments on the first version of the article were made, so I have no more comments. The article can be accepted as it is now submitted.
Author Response
We thank you very much for your confirmation of our revised manuscript and the careful review.
Reviewer 3 Report
This second version is strongly improved and much more interesting. All my concerns were addressed and the results are well described, and put into context.I still have some problems with the layout/presentation which definitively need to be improved prior to publication (I had the feeling to read a draft, many formulas are not centered etc). Please check. A few additional remarks in the introduction can be found in the attached document. Nice work, I encourage you to carry on.
Comments for author File: 
Comments.pdf
Author Response
Point 1: This second version is strongly improved and much more interesting. All my concerns were addressed and the results are well described, and put into context. I still have some problems with the layout/presentation which definitively need to be improved prior to publication (I had the feeling to read a draft, many formulas are not centered etc). Please check. A few additional remarks in the introduction can be found in the attached document. Nice work, I encourage you to carry on.
Response 1: We have revised the layout/presentation according to your comments. We thank you very much for your constructive suggestions on the manuscript and the encouragements on the study.
Author Response File: Author Response.docx
