Spatial–Temporal Characteristics of Freezing/Thawing Index and Permafrost Distribution in Heilongjiang Province, China
Round 1
Reviewer 1 Report
The authors did a good job and obviously will contribute in both climate change and engineering sector, as disappearing permafrost may cause damage to infrastructure and other activities.
My only suggestion is what if we draw the conclusion for the future data analysis
Author Response
The review's comment:“My only suggestion is what if we draw the conclusion for the future data analysis”.
The authors' answer: Thanks very much for your comments; For the analysis of permafrost using future climate data, we have also considered using CMIP6 climate data for permafrost distribution analysis, but since CMIP6 climate data only has temperature, there is a certain error for the analysis of permafrost distribution, so we consider using the past 50 years of temperature and ground temperature data for the trend analysis of permafrost distribution, and the resulting correlation is very informative for future permafrost research and engineering construction in permafrost
Reviewer 2 Report
The paper is devoted to a topical issue, the processes of freezing/thawing index and permafrost distribution. There are a number of comments to the paper:
1. The significance of the freeze-thaw index has been described sufficiently in the introduction section, it is recommended to add the effects of freeze-thaw to the introduction and abstract.
2. Figure 7 Suggested changes to English.
3. The correlation coefficients in Figure 9 should be defined, and the calculation method should be given.
4. The analytical approach of Figure 6 should be given.
5. The authors performed a large amount of work, the results obtained have novelty, but the conclusion part is not obvious, and it is suggested to optimize the conclusion part.
6. The findings of 4.3 should be reflected in conclusions.
Author Response
- The review's comment: The significance of the freeze-thaw index has been described sufficiently in the introduction section, it is recommended to add the effects of freeze-thaw to the introduction and abstract.
The authors' answer: Thanks very much for your comments; the abstract and introduction have been restructured and the related contents have been modified, and the effects of freezing and thawing have been added.
- The review's comment: Figure 7 Suggested changes to English.
The authors' answer: Thanks very much for your comments; Due to our mistake, the labeling of Figure 7 is wrong, we have re-under revision and correction.
- The review's comment: The correlation coefficients in Figure 9 should be defined, and the calculation method should be given.
The authors' answer: Thanks very much for your comments; the method of correlation analysis has been given in “2.3.3”.
- The review's comment: The analytical approach of Figure 6 should be given.
The authors' answer: Thanks very much for your comments; the analytical approach of Figure 6 has been given in “2.3.3”.
- The review's comment: The authors performed a large amount of work, the results obtained have novelty, but the conclusion part is not obvious, and it is suggested to optimize the conclusion part.
The authors' answer: Thanks very much for your comments; the conclusion section has been streamlined and modified.
- The review's comment: The findings of 4.3 should be reflected in conclusions.
The authors' answer: The findings of 4.3 are already reflected in the revised conclusions.
Reviewer 3 Report
Comments for author File: 
Comments.pdf
Author Response
- The review's comment: The "Abstract" should give the purpose of the article, what data and methods were used to analyze the study subjects, the new findings and developments of the article and the significance and value of the study. However, the structure of the abstract section of this paper is rather confusing, and the purpose of the study is not given. The conclusion section of the study only lists the data changes of the freezing/thawing index, and there are no substantial and new conclusions. It is suggested that the abstract section should be rewritten, and the structure should be rationalized.
The authors' answer: Thanks very much for your comments; the abstract section has been restructured and the abstract has been revised
- The review's comment: The "Introduction" section should firstly introduce the background of this paper in detail, then introduce the existing research progress, then introduce the purpose and significance of this paper, as well as the scientific problem to be solved. Finally, the value and significance of the results of this paper should be presented. Such as: What is already known in the open literature? What is missing (i.e., research gaps)? What needs to be done, why and how? The structure of the "Introduction" part of this paper is confusing and the regulations are not clear. For example, the first paragraph of the "Introduction" section of this paper introduces the background of the study and also summarizes the progress of the study, which is rather confusing, and it is suggested to reorganize the structure of the "Introduction" section.
The authors' answer: The introduction section has been revised for the background of the study, and the structure has also been adjusted.
- The review's comment: The "Introduction" section should be closely related to the topic when summarizing the existing research progress, and avoid listing what XXX has done. In this paper, we summarize the progress of research on permafrost distribution and freezing/thawing index, but you do not clearly point out the gaps in the current research, and the scientific questions raised are not sharping and challenging enough, and the simple introduction of a certain work that has been rarely done is not enough to support the importance of this research. In the last paragraph, the main research work of this paper is summarized in points, but there are too many points and it seems to be redundant, so we suggest making a concise summary.
The authors' answer: The introduction section has been revised for the background of the study, and the structure has also been adjusted. The presentation of some of the contents has also been revised to reduce the verbosity and repetition of language.
- The review's comment: In "Data and Methods", the data sources and study area and periods should be clearly stated; the analytical methods used should also be given, and if existing methods are used, the corresponding equations and citations should be given, with emphasis on the newly developed methods. For example, the analysis method of "4.1 Correlation between freezing/thawing index and MAAT" should be explained. In addition, the source of DEM data used in this paper is not given.
The authors' answer: the analysis method of "4.1 Correlation between freezing/thawing index and MAAT" has been given in 2.3.3, the source of DEM data used in this paper has been given in 2.2.
- The review's comment: In "Results and Discussion", should avoid repeatedly listing the data in the charts, focus on summarizing the commonalities and characteristics behind the data, and highlight the patterns and meanings of the data in the analysis charts. The discussion will focus on the new developments and improvements of this study compared with previous studies, and the uncertainties and shortcomings of the results of this paper. This paper follows the analysis of the results with a discussion of related issues. However, the discussion of the reasons for the spatial variation of the freezing/thawing index in "3.1Spatial variation characteristics of the freezing/thawing index" is a bit insufficient, and it is suggested to add more discussion.
The authors' answer: Much analysis and discussion has already taken place in this section, and we have also re-added to the discussion.
- The review's comment: "Conclusion" is not the same as result, should avoid repeating too detailed results in the conclusion section, and instead condense and improve them. In this paper, the author draws 4 points of conclusion, but the "conclusion" part is mostly a repetition of the results of the analysis, without summary and sublimation. It is suggested that the conclusion section should be re-summarized with no more than 5 points.
The authors' answer: The conclusion section has been revised according to the content and summarizes the 4 points of conclusion.
- The review's comment: Clear statements of the novelty of the work should also appear briefly in the Abstract and Conclusions sections.
The authors' answer: The revised abstract and conclusions have captured the important findings of this paper.
- The review's comment: Air and ground freezing/thawing index, as the most important keyword in this paper, should be explained clearly when it first appears.
The authors' answer: The first appearance of the air and ground freezing/thawing index was clearly explained, and the abbreviation was used in the subsequent.
- The review's comment: Line 49, "IPCC (2021)" should be used in full title in its first appearance and should not be abbreviated.
The authors' answer: "IPCC (2021)" has been revised to “Intergovernmental Panel on Climate Change (IPCC) 2021”.
- The review's comment: Line 101, "atmospheric" should be "air".
The authors' answer: we have modified “atmospheric" to "air".
- The review's comment: Line 99,103,105,107,143, "freeze-thaw indices" should be "freezing/thawing index ".
The authors' answer: we have modified "freeze-thaw indices" to "freezing/thawing index ".
- The review's comment: Line 99, "thaw index" should be "thawing index".
The authors' answer: we have modified "thaw index" to "thawing index".
- The review's comment: Line 119-120, "32.77 × 104km2 to 27.10 × 104km2" should be "32.77 × 104km2 to 27.10 × 104km2".
The authors' answer: we have modified "32.77 × 104km2 to 27.10 × 104km2" to "32.77 × 104km2 to 27.10 × 104km2".
- The review's comment: The legend section of Figure 1 is recommended to be placed in the margin for better aesthetics.
The authors' answer: we have modified Figure 1.
- The review's comment: In the "Data Sources" section, the date of acquisition of meteorological data and remote sensing data should also be given, e.g., (accessed on 1 January 2020).
The authors' answer: the date of acquisition of meteorological data and remote sensing data we have added in“Supplementary Materials”.
- The review's comment: In the "Data Sources" section, line 186-202, the specifics of the interpolation method for missing measurement data are overly described and it is recommended that they be further streamlined and the citations given.
The authors' answer: the specifics of the interpolation method for missing measurement data has streamlined.
- The review's comment: Line 233,236, "Ti" should be "Ti".
The authors' answer: we have modified "Ti" to "Ti".
- The review's comment: In the "Figure 2,3,4,5,8,9", should provide explanation for subfigures in caption and explain the meaning of "**".
The authors' answer: we have added explanation for subfigures in caption and explain the meaning of "**".
- The review's comment: In the "Figure 2", there should be a space between "1981-2004a" and "(before amendment)"; the rest of the notation is similar.
The authors' answer: We have modified all the figures in this article as requested.
- The review's comment: In the "Figure 5", the "Line trend" should use the same color.
The authors' answer: We have modified Figure 5.
- The review's comment: Figure 7 suggested changes to English.
The authors' answer: We have modified Figure 7.
- The review's comment: Line 421, the "test" should be "tests".
The authors' answer: We have modified "test" to "tests".
- The review's comment: In the "Figure 9", should add the unit of "temperature and freezing/thawing index".
The authors' answer: We have added the unit of "temperature and freezing/thawing index" in the "Figure 9".
- The review's comment: The correlation between MAAT and air/ground freezing/thawing index is not significant from Figure 9, whether this analysis can explain the results of the study.
The authors' answer: By analyzing the relationship between air temperature and freeze-thaw index, it is not only possible to further clarify the relationship between air temperature and atmospheric freeze-thaw index, but also to provide reference for the subsequent analysis of permafrost distribution using the freeze-thaw index model.
- The review's comment: There should be a space before the "/°C、/(℃•d )" in the labeling of all figures.
The authors' answer: We have modified all the figures in this article as requested.
- The review's comment: Line 449, the "Daxing’an Xiaoxing’an mountains" should be "Daxing’an and Xiaoxing’an Mountains".
The authors' answer: We have modified the "Daxing’an Xiaoxing’an mountains" to "Daxing’an and Xiaoxing’an Mountains".
- The review's comment: Line167, 291, the "Zhangguangcailing" should be "Zhangguang’cai Mountains ".
The authors' answer: We have modified the "Zhangguangcailing" to "Zhangguang’cai Mountains ".
- The review's comment: "Daxing'an" appears several times in this paper, and it is suggested that all of them should be consistent.
The authors' answer: We have standardized the spelling of "Daxing'an" throughout the paper.
- The review's comment: The names of all figures in the article should be concise and condensed, while expressing the content of the figure.
The authors' answer: We have made appropriate changes and adjustments to the image names in the full paper.
- The review's comment: The format of all references should be modified according to the journal's requirements.
The authors' answer: The format of the references has been modified in accordance with the journal's requirements.
- The review's comment: Suggest appropriate embellishments to the English language.
The authors' answer: The language of this article has been embellished.
Author Response File: Author Response.pdf
