The Spatiotemporal Surface Velocity Variations and Analysis of the Amery Ice Shelf from 2000 to 2022, East Antarctica
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsIn this manuscript titled as “The spatiotemporal surface velocity variations and analysis of Amery ice shelf, East Antarctica”, the authors used the DInSAR and Offset tracking method to obtain the monthly average surface velocity of the Amery ice shelf between October 2017 and October 2023, and inter-annual surface velocity from the ITS_LIVE product. Then their analyzed the inter-annual and intra-annual glacier velocity changes, and found the spatial-temporal changes of velocity of the Amery ice shelf. In general, this article is well written, the methods and the conclusion are credible, and it is recommended that you accept this article after correcting a series of minor problems.Detailed comments are below.
1. In line 31, (Gardner, Moholdt et al. 2018, Shen, Wang et al. 2018) , this citation format does not appear to meet the requirements of remote Sensing journals. Please correct
2. Line 37, what's the remote sensing here? Satellite remote sensing? We know that there are many types of remote sensing, and we should provide references to some of the main remote sensing methods. For example, differential interferometric synthetic aperture radar (DInSAR) data are used in this article. Please add an introduction to this.
3. The unit marking related to ice velocity in Figure 2 should be modified.
4. Lines 183-191, the black boxes in Figure 3 represents a vague meaning. I suggest that the track numbers of different Sentinel-1 images must be annotated.
5. In line 291, the table position should be adjusted to the correct position
6. 336-337 lines, the clarity of Figure 8 is not enough, the place names on the right side of the figure can not be seen clearly. And the ruler of the drawing does not conform to the specification
7. Line 353, “The results indicated no seasonal variation in the surface velocities of the FG and MG ice streamlines”. From the surface flow velocity changes of MG and LG ice flow lines in Figure 10, it can be seen that the surface velocity changes of the two ice flow lines, but the seasonal changes are not obvious.
8. Figure 10 is in the wrong position
9. Line 397, “4.1. Effect of ocean temperature and AIS thickness on variations in inter-annual surface velocity”. The annotation of the title needs to be changed.
10. The slope of the linear regression in figure 12 should be given
11. Line 500, “The correlation coefficients between variation in ocean temperature of P3 and variations in surface velocity at LG7 and LG2 were 0.178 and 0.144, respectively”. The calculation and description of the correlation coefficient are not accurate.That should be modified.
12. Line 532, “There inter-annual variation in the surface velocity of the AIS was spatially uneven from 2000 to 2022”.The spatial description of the spatiotemporal variation of surface velocity is inaccurate and needs to be modified.
13. Lines 547-579，“The calving event on the AIS front on the 28th September, 2019, had no impact on the variation in surface velocity, which could be attributed to the location of the calved area on an insensitive area of the AIS front” was a misinterpretation of the calving event. The calving event of the Amery ice shelf is located within the safety belt and can be explained in reference “the safety band of Antarctic ice shelves”.
14. English is not my mother tongue, the present English expression of the article is suitable for me, may still need to consider whether the editor needs to improve the quality of the language.
Author Response
Dear Editor and Reviewer:
Thank you very much for reviewing our manuscript. First of all, we would like to take this opportunity to thank the reviewer for your constructive comments and relevant questions. By adding the answers/revisions to these questions to the revised version of the manuscript, we feel that the quality of the manuscript has been improved. A revised manuscript has been submitted, and all corrections/modifications are only included in the revised manuscript for the sake of non-repeat. Extra answers to your concerns and questions are presented as follows.
Comment 1: In line 31, (Gardner, Moholdt et al. 2018, Shen, Wang et al. 2018) , this citation format does not appear to meet the requirements of remote Sensing journals. Please correct
Response 1: Thank you for your suggestions. We have modified the citation format according to the remote Sensing journals.
Comment 2: Line 37, what's the remote sensing here? Satellite remote sensing? We know that there are many types of remote sensing, and we should provide references to some of the main remote sensing methods. For example, differential interferometric synthetic aperture radar (DInSAR) data are used in this article. Please add an introduction to this.
Response 2: Thank you for pointing this error out. We agree with this comment. We have provide the DInSAR and sentinel-1A data in the revised manuscript. Besides, we have added the introduction of sentinel-1A at the section 2.2 and added Figure 1 in the revised manuscript.
Comment 3: The unit marking related to ice velocity in Figure 2 should be modified.
Response 3: Thank you for pointing this error out. We have redrawn Figure 3 in the revised manuscript (Figure 2 in the original manuscript) and modified the unit marking.
Comment 4: Lines 183-191, the black boxes in Figure 3 represents a vague meaning. I suggest that the track numbers of different Sentinel-1 images must be annotated.
Response 4: Thank you for your suggestions. We have modified the label marking in the Figure 4 in the revised manuscript (Figure 3 in the original manuscript) and the extent of different Sentinel-1 have been annotated by the track numbers.
Comment 5. In line 291, the table position should be adjusted to the correct position
Response 5: Thank you for pointing this error out. We have adjusted the table position in the revised manuscript.
Comment 6. 336-337 lines, the clarity of Figure 8 is not enough, the place names on the right side of the figure cannot be seen clearly. And the ruler of the drawing does not conform to the specification
Response 6: Thank you for your suggestions. We have redrawn Figure 9 in the revised manuscript (Figure 8 in the original manuscript), and have improved the resolution of the Figure 9.
Comment 7. Line 353, “The results indicated no seasonal variation in the surface velocities of the FG and MG ice streamlines”. From the surface flow velocity changes of MG and LG ice flow lines in Figure 10, it can be seen that the surface velocity changes of the two ice flow lines, but the seasonal changes are not obvious.
Response 7: Thank you for your suggestions. We agree with this comment and it can be seen that the surface velocity changes of the FG and MG ice streamlines, but the seasonal changes are not obvious. We have modified this part of the content in section 3.4 in the revised manuscript.
Comment 8. Figure 10 is in the wrong position
Response 8: Thank you for pointing this error out. We have modified this error and the subgraph has been mapped to the description in section 3.4 in the revised manuscript.
Comment 9. Line 397, “4.1. Effect of ocean temperature and AIS thickness on variations in inter-annual surface velocity”. The annotation of the title needs to be changed.
Response 9: Thank you for your suggestions. We agree with this comment. The title changed to “Analysis of factors of inter-annual variation of surface velocity” in section 4.1 in the revised manuscript.
Comment 10. The slope of the linear regression in figure 12 should be given
Response 10: Thank you for your suggestions. We have added the slope of the linear regression in the Figure 13 in the revised manuscript (Figure 12 in the original manuscript).
Comment 11. Line 500, “The correlation coefficients between variation in ocean temperature of P3 and variations in surface velocity at LG7 and LG2 were 0.178 and 0.144, respectively”. The calculation and description of the correlation coefficient are not accurate.That should be modified.
Response 11: Thank you for pointing this error out. We agree with this comment. We have removed this part of the content. Their relationship between ocean temperature and velocity changes is explained by sensitivity.
Comment 12. Line 532, “There inter-annual variation in the surface velocity of the AIS was spatially uneven from 2000 to 2022”.The spatial description of the spatiotemporal variation of surface velocity is inaccurate and needs to be modified.
Response 12: Thank you for pointing this error out. We agree with this comment. We have modified this part of content and changed to “the variations in surface velocity are not consistent in different spatial region of AIS” in the revised manuscript.
Comment 13. Lines 547-579，“The calving event on the AIS front on the 28th September, 2019, had no impact on the variation in surface velocity, which could be attributed to the location of the calved area on an insensitive area of the AIS front” was a misinterpretation of the calving event. The calving event of the Amery ice shelf is located within the safety belt and can be explained in reference “the safety band of Antarctic ice shelves”.
Response 13: Thank you for your suggestions. We agree with this comment. We have modified this part of content and cited two references about the safety band of Antarctic ice shelves in the revised manuscript.
Comment 14. English is not my mother tongue, the present English expression of the article is suitable for me, may still need to consider whether the editor needs to improve the quality of the language.
Response 14: Thank you for your suggestions. We have a professional English language service to check the writing language.
Reviewer 2 Report
Comments and Suggestions for AuthorsThis manuscript observes the spatiotemporal changes in the surface velocity of the Amery Ice Shelf (AIS) using the ITS_LIVE product and Sentinel-1 DInSAR and offset tracking, and interprets the influencing factors. Although there is nothing new in the methodology or the way the results are interpreted, long-term monitoring of the surface velocity of the AIS provides very important information for cryospheric science and climate change research, so this manuscript may attract the interest of researchers in related fields.
The authors have appropriately presented the research results and conducted the discussion. However, the introduction, data, and methodology are very poorly written. I believe that the authors can sufficiently improve the manuscript, and it would be good to conduct re-review after the manuscript is revised.
Here are the detailed comments:
Line 2: Add the monitoring period to the title.
Line 42: Correct "optimal" to "optical." Review and correct typographical errors throughout the manuscript.
Line 46: Clearly distinguish between Sentinel-1A and 1B and complete the sentence.
Line 47-48: Add appropriate references.
Line 55: What resolution is meant here? Is it temporal resolution?
Line 56: Are there no tropospheric effects?
Line 71: The items (1) to (5) presented as research purposes by the authors are actually distant from the research objectives. Especially items (1) to (3) pertain to the research methods, not the objectives. Rewrite this paragraph.
The current introduction is focused on the methodology. The necessity of studying AIS flow velocity, various characteristics of AIS revealed in previous studies, and the limitations of existing research should be detailed.
Line 84: There is no explanation of how the inter-annual variation in surface velocity was characterized. The same applies to Section 2.2.
The description of the SAR data used in the research is very insufficient.
In Section 2.2.2, ionospheric correction is emphasized, but there is almost no explanation of the correction method.
Section 2.2.3 is one of the core research methods of this study. However, it is currently difficult to understand how the DInSAR and offset tracking results were combined.
Section 2.5: There is no information on the data used for ice thickness estimation.
Line 251: What is the reason for the various levels of error? Could it be due to resolution or the method of measuring flow velocity?
Line 268: MEaSUREs data was used to verify the flow velocity measured by the authors. MEaSUREs can also be used to verify the ITS_LIVE product.
Increase the resolution of Figures 6 and 16.
The results and discussion are relatively detailed. However, some parts of the results and discussion may need to be appropriately revised following the modifications to the introduction and methodology sections.
Author Response
Dear Editor and Reviewer:
This manuscript observes the spatiotemporal changes in the surface velocity of the Amery Ice Shelf (AIS) using the ITS_LIVE product and Sentinel-1 DInSAR and offset tracking, and interprets the influencing factors. Although there is nothing new in the methodology or the way the results are interpreted, long-term monitoring of the surface velocity of the AIS provides very important information for cryospheric science and climate change research, so this manuscript may attract the interest of researchers in related fields.
The authors have appropriately presented the research results and conducted the discussion. However, the introduction, data, and methodology are very poorly written. I believe that the authors can sufficiently improve the manuscript, and it would be good to conduct a re-review after the manuscript is revised.
Response: Thank you very much for reviewing our manuscript. First of all, we would like to take this opportunity to thank the reviewer for your constructive comments and relevant questions. By adding the answers/revisions to these questions to the revised version of the manuscript, we feel that the quality of the manuscript has been improved. A revised manuscript has been submitted, and all corrections/modifications are only included in the revised manuscript for the sake of non-repeat. Extra answers to your concerns and questions are presented as follows.
Comment 1： Line 2: Add the monitoring period to the title.
Response 1: Thank you for your suggestions. We have modified the title and added the monitoring period in the revised manuscript.
Comment 2：Line 42: Correct "optimal" to "optical." Review and correct typographical errors throughout the manuscript.
Response 2: Thank you for pointing this error out. We have corrected and reviewed typographical errors in the revised manuscript.
Comment 3：Line 46: Clearly distinguish between Sentinel-1A and 1B and complete the sentence.
Response 3: Thank you for pointing this error out. We have modified this section by adding a description of Sentinel-1A and Sentinel-1B data in the revised manuscript.
Comment 4: Line 47-48: Add appropriate references.
Response 4: Thank you for your suggestion. We have added three appropriate citations in the revised manuscript.
Comment 5: Line 55: What resolution is meant here? Is it temporal resolution?
Response 5: Thank you for pointing this error out. Yes, the resolution here refers to the temporal resolution, and we have revised this part of the content in the revised manuscript.
Comment6: Line 56: Are there no tropospheric effects?
Response 6: Thank you for pointing this error out. We have added the tropospheric effect in the revised manuscript, which is part of the atmospheric effect. Besides, in the Antarctic region, atmospheric effects have limited influence on DInSAR.
Comment 7: Line 71: The items (1) to (5) presented as research purposes by the authors are actually distant from the research objectives. Especially items (1) to (3) pertain to the research methods, not the objectives. Rewrite this paragraph.
Response 7: Thank you for your suggestions. We agree with this comment. We have re-written the content of this paragraph, highlighting the main methods and processes of AIS surface velocities extraction. At the same time, the factors affecting AIS surface velocity variation were also investigated.
Comment 8: The current introduction is focused on the methodology. The necessity of studying AIS flow velocity, various characteristics of AIS revealed in previous studies, and the limitations of existing research should be detailed.
Response 8: Thank you for pointing this error out. We have supplemented the shortcomings of the existing study of AIS in the revised manuscript. Previous studies on the surface velocity of AIS mainly focused on the changes in the local area of AIS, and there was a lack of research on the overall surface flow velocity of AIS. At the same time, due to the limited time resolution of the SAR image, it lacks the change of velocity time series.
Comment 9: The description of the SAR data used in the research is very insufficient.
Response 9: Thank you for pointing this error out. We have supplemented the description of the SAR data and also plotted the coverage of the Sentinel-1A image (Figure 1) in section 2.2 in the revised manuscript.
Comment 10: In Section 2.2.2, ionospheric correction is emphasized, but there is almost no explanation of the correction method.
Response 10: Thank you for pointing this error out. We have added the description of the ionospheric correction and have supplemented the ionospheric correction formula in section 2.2.2 in the revised manuscript.
Comment11: Section 2.2.3 is one of the core research methods of this study. However, it is currently difficult to understand how the DInSAR and offset tracking results were combined.
Response 11: Thank you for pointing this error out. We have supplemented the description of the combined approach of DInSAR and Offset tracking technology in the revised manuscript. At the same time, the advantages of the combined method are highlighted and the characteristics of AIS surface flow rate are introduced.
Comment 12: Section 2.5: There is no information on the data used for ice thickness estimation.
Response 12: Thank you for your suggestions. We have added the description of the data used for ice thickness in section 2.5 in the revised manuscript. The time series of ice sheet elevations can be derived by combining Envisat and cryostat-2 altimetry data.
Comment 13: Line 251: What is the reason for the various levels of error? Could it be due to resolution or the method of measuring flow velocity?
Response 13: Thank you for your suggestions. We have explained the causes of these surface velocity errors in the revised manuscript, and those errors derived from the residual phase errors and so on.
Comment14: Line 268: MEaSUREs data was used to verify the flow velocity measured by the authors. MEaSUREs can also be used to verify the ITS_LIVE product.
Response 14: Thank you for your suggestions. In this work, we have chosen the surface velocities of rock points near AIS to verify the ITS_LIVE product.
Comment 15: Increase the resolution of Figures 6 and 16.
Response 15: Thank you for pointing this error out. We have redrawn Figures 7 and 17 in the revised manuscript (Figures 6 and 16 in the original manuscript) and improved their resolution.
Comment 16: The results and discussion are relatively detailed. However, some parts of the results and discussion may need to be appropriately revised following the modifications to the introduction and methodology sections.
Response 16: Thank you for your suggestions. We have adjusted the results and discussions in the revised manuscript according to the modifications to the introduction and methodology sections.
Reviewer 3 Report
Comments and Suggestions for AuthorsDear authors,
You present an interesting work on AIS. I suggest that you check English language as I detected some minor flaws. Also it would be nice to see an illustration presenting the area of interest.
Regards
Comments on the Quality of English LanguageEnglish language has to be improved. I suggest some minor corrections
Author Response
Comment: You present an interesting work on AIS. I suggest that you check the English language as I detected some minor flaws. Also, it would be nice to see an illustration presenting the area of interest.
Response: Thank you very much for reviewing our manuscript. First of all, we would like to take this opportunity to thank the reviewer for your constructive comments and relevant questions. By adding the answers/revisions to these questions to the revised version of the manuscript, we feel that the quality of the manuscript has been improved. In addition, we have had a professional English language service to check the writing language.
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsI appreciate the authors for revising the manuscript based on the review comments. However, some review comments have not been properly addressed, and there are still several parts of the revised manuscript that need further revisions.
1. Although it was suggested that the necessity of studying the flow velocity of AIS should be emphasized in the introduction, this has not been reflected.
2. Number the equations, and write the first letter of "where" that follows the equations in lowercase.
3. The method of combining DInSAR range velocity and offset tracking azimuth velocity needs to be described in more detail. Is the DInSAR range velocity related to slant range or ground range? How did you address the spatial resolution difference between the two flow velocity data? Is the equation representing v correct?
4. It is difficult to see the thickness of AIS in Figure 5. The thickness is mapped on the ice sheet as well. Can this also be derived based on the assumption of hydrostatic equilibrium?
5. Following the revisions to the introduction and methodology, it seems that the results and discussion sections need to be supplemented, but there is little supplementation done in these sections.
Author Response
Comments and Suggestions for Authors
I appreciate the authors for revising the manuscript based on the review comments. However, some review comments have not been properly addressed, and there are still several parts of the revised manuscript that need further revisions.
Thank you very much for reviewing our manuscript again. We have considered your comments carefully and highlighted the corresponding modifications in the revised manuscript.
Comment 1: Although it was suggested that the necessity of studying the flow velocity of AIS should be emphasized in the introduction, this has not been reflected.
Response 1: Thank you for pointing out this issue. We underscored the importance of monitoring the surface velocity of AIS in the introduction. We also clarified that variations in surface flow velocity constitute the primary driver of changes within the AIS. Investigating these variations is crucial for assessing the stability of the Amery Ice Shelf and highlighted the significance of studying surface velocity changes on the Amery Ice Shelf..
Comment 2: Number the equations, and write the first letter of "where" that follows the equations in lowercase.
Response 2: Thank you for pointing this error out. We agree with this comment. We have numbered the formulas and revised the first letter of “where” that follows the equations (3).
Comment 3: The method of combining DInSAR range velocity and offset tracking azimuth velocity needs to be described in more detail. Is the DInSAR range velocity related to slant range or ground range? How did you address the spatial resolution difference between the two flow velocity data? Is the equation representing v correct?
Response 3: Thank you for your suggestions. We have modified the method of combining DInSAR range velocity and offset tracking azimuth velocity. Firstly, we convert the surface velocity in the line of sight direction to the surface velocity in the ground range surface velocity . Then, we down-sample the ground range surface velocity derived from DInSAR to achieve the same spatial resolution as that azimuth surface velocity derived from offset tracking.
Comment 4: It is difficult to see the thickness of AIS in Figure 5. The thickness is mapped on the ice sheet as well. Can this also be derived based on the assumption of hydrostatic equilibrium?
Response 4: Thank you for pointing out this issue. We have redrawn Figure 5 and added Figure 5 (a). Figure 5 (a) shows the thickness of the Amery Ice Shelf, while Figure 5 (b) represents the monitoring points for the average monthly ice shelf thickness.
Comment 5: Following the revisions to the introduction and methodology, it seems that the results and discussion sections need to be supplemented, but there is little supplementation done in these sections.
Response 5: Thank you for your suggestions. We have revised the discussion sections. We have summarized the factors influencing the changes in interannual surface velocity and monthly average surface velocity of the Amery Ice Shelf in the discussion section.
Author Response File: 
Author Response.docx
