Analysis of Change in Summer Extreme Precipitation in Southwest China and Human Adaptation
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsGeneral comments.
In the introduction of this paper, you mentioned several natural mechanisms to explain the precipitation patterns. However, the changes in land use, which play a significant role in climate change, were omitted. It's important to consider these changes, along with the natural mechanisms, when assessing climate change.
Each analysis is pertinent and relevant to the aim of the work when comparing both different periods P1 and P2. What can you say about the critical years, 1997 – 1999? Could you determine the possible causes of this change in SAH and WPSH?
Specific comments:
L 33-39 The paragraph is not clear. Please rephrase.
The caption in Figure 7 does not mention panel c).
In Table 3, the critical event from 1998 is not mentioned. Why is that?
There are typos at least in Lines 353, 451 and 460.
Comments on the Quality of English LanguageThe Introduction needs editing.
Author Response
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Response to Reviewer 1 Comments
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Summary
Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files.
Point-by-point response to Comments and Suggestions for Authors
Comments 1: In the introduction of this paper, you mentioned several natural mechanisms to explain the precipitation patterns. However, the changes in land use, which play a significant role in climate change, were omitted. It's important to consider these changes, along with the natural mechanisms, when assessing climate change.
Response 1:Thank you for pointing this out. We agree with this comment. The mechanism of land use influence on precipitation is a complex process, involving changes in surface albedo, evaporation and evapotranspiration, greenhouse gas concentration and so on. Anthropogenic land use has significant impacts on the earth’s climate, carbon cycle and water balance. Typically, land use alters the biophysical properties of the land cover, such as albedo, evapotranspiration and roughness, which in turn affects land–atmosphere energy and water exchange. Land use can also affect the carbon cycle between the land and atmosphere through biogeochemical emissions and uptake.
On the one hand, different land use patterns can significantly change the surface albedo. For example, after deforestation, surface vegetation decreases and exposed areas such as soil and rocks increase, leading to an increase in surface albedo. This, in turn, reduces the amount of solar radiation absorbed by the surface, affecting the temperature and humidity of the atmosphere, thereby altering the water cycle in the atmosphere and affecting the distribution of precipitation.
On the other hand, land use change, especially deforestation and agricultural activities, can lead to increased concentrations of greenhouse gases such as carbon dioxide in the atmosphere. This will exacerbate the greenhouse effect and raise global temperatures. Rising temperatures, in turn, alter the distribution and intensity of precipitation by affecting atmospheric circulation and the water cycle. In addition, in urban areas, the impact of land use change on urban local extreme precipitation is particularly obvious. Hardened urban surfaces and dense high-rise buildings can change local weather and climate conditions, making extreme rainfall more frequent.
However, considering that this paper is studying the change of extreme precipitation and human adaptation in a large spatial scale. Therefore, We add the above to the discussion section. We intend to take this as an opportunity to conduct our next research. The revision we have made can be found in revised manuscript L 514-536.
Anyway, your opinion is very important to us and we would like to thank you again.
Comments 2: Each analysis is pertinent and relevant to the aim of the work when comparing both different periods P1 and P2. What can you say about the critical years, 1997 – 1999? Could you determine the possible causes of this change in SAH and WPSH?
Response 2:Thank you for pointing this out. The critical years, 1997-1999, was an important dividing period for the study of the change of summer extreme precipitation in southwest China. Before this period, the summer extreme precipitation in southwest China was gradually decreasing, but after that, the extreme precipitation gradually increased. In this study, we used two different mutation test methods to determine the mutation point of extreme precipitation, and the conclusions were consistent.
The reasons for the changes of SAH and WPSH are the key issues discussed in this study, and also the critical factors to explain the above changes of summer extreme precipitation in southwest China. The Tibetan Plateau (TP) sensible heat and tropical sea surface temperature are important factors that promote the changes of SAH and WPSH.
The spring SSH over the TP was the key factor for maintaining the intensity of the SAH. SSH was the main energy source of lower troposphere air and an essential component of the surface heat balance. The uneven spatial distribution and interannual variation in SSH inevitably led to differences in the surface heating of the lower-troposphere air, affecting local weather and climate. The spring SSH over the TP had a high positive correlation with the SAH indices. The SSH over the central TP (85°E–95°E) had the highest correlation with the SAH intensity, indicating that it was a main factor that maintained the intensity of the SAH.
The Western Pacific warm pool (WPWP) was a crucial thermal factor for maintaining and strengthening the intensity of WPSH. Cooling (Figures 13d and 13e) and insignificant heating (Figure 13f) of the WPWP were the direct causes of the attenuated influence range and intensity of the WPSH in P1 (Figure 5b). The evident heating of the WPWP (Figures 13g-13i) led to the intensification of the WPSH in P2 and its westward extension into mainland China (Figure 5e).
Comments 3: L 33-39 The paragraph is not clear. Please rephrase.
Response 3: Thank you for pointing this out. We agree with this comment. Therefore, we rephrase these sentences. The change we have made can be found in the revised manuscript L 33-37.
Comments 4: The caption in Figure 7 does not mention panel c).
Response 4: Thank you for pointing this out. Figure 7c showed the standardized values of the average spring SSH over the TP. The spring SSH over the TP showed a downward trend from the early 1980s to the late 1990s and then an upward trend. This trend was consistent with the trend of extreme precipitation in the SWC and subtropical high indices. The SSH can increase the heat of the lower troposphere air and moisture content in the air, thus, the SSH was related to the occurrence and development of extreme precipitation. This change can be found in revised manuscript L 283-288.
Comments 5: In Table 3, the critical event from 1998 is not mentioned. Why is that?
Response 5: Thank you for pointing this out. According to the results of Fig.1 and Fig.2, it can be seen that around 1997-1998, the trend of summer extreme precipitation in southwest China had a sudden change. On this basis, we also desired to further analyze the differences in circulation patterns that led to the different characteristics of REPEs in the two periods more completely and clearly. In order to achieve this goal, we selected REPEs from 1992 to 1996 and from 2017 to 2021, then performed a composite analysis on them. The REPEs of 1992-1996 and 2017-2021 were used because the REPEs that occurred during these two periods were the most representative cases, which can reflect the characteristics of the atmospheric circulation patterns that triggered REPEs to the greatest extent.
Considering that 1997/1998 was right around the abrupt change point of two periods. Whether the event from 1998 was classified into Sub-P1 or Sub-P2, it will statistically obscure the signal of other extreme precipitation events, making the composite analysis less scientific. Therefore, the extreme precipitation event that occurred in 1998 was not mentioned in table 3. However, this arrangement did not affect the reasonableness of our conclusion.
Comments 6: There are typos at least in Lines 353, 451 and 460.
Response 6: Thank you for pointing this out. We agree with this comment. Therefore, we correct these typos. The corrections we have made can be found in the revised manuscript L 351, L 449 and L 457-458.
3. Response to Comments on the Quality of English Language
Points 1: The Introduction needs editing.
Response 1: Thank you for pointing this out. We agree with this comment. Therefore, we rephrase the introduction. The revision we have made can be found in the revised manuscript L 33-37.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsDear Authors,
I have read your scientific article with pleasure. I must praise that the structure of the publication is very good, the figures and tables are clear and substantively justified. The research methodology is correct. The research questions are posed at the end of the "Introduction" chapter. However, I have a few suggestions, as a reviewer, that can raise the article to an even higher substantive level, namely:
1. The discussion chapter should definitely be expanded. With such an extensive and detailed presentation of the research results, these results should be discussed more extensively with the literature on the subject.
2. In connection with the expansion of the discussion chapter, it is also necessary to include at least 10-15 additional items of new literature in these deliberations and of course place them in the list of references.
3. The conclusions should be bulleted and referred specifically to the research questions. This chapter can be started with a short summary, then bulleted conclusions and at the end a few sentences about the limitations of this research and what are the plans for future research on this topic. After taking into account my suggestions, the article can be published.
Good luck
Comments on the Quality of English LanguageMinor editing of English language required.
Author Response
Response to Reviewer 2 Comments
Summary
Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files.
Point-by-point response to Comments and Suggestions for Authors
Comments 1: The discussion chapter should definitely be expanded. With such an extensive and detailed presentation of the research results, these results should be discussed more extensively with the literature on the subject.
Response 1: Thank you for pointing this out. We agree with this comment. We have already expanded discussion chapter by studying the mechanism of land use influence on precipitation and local human adaption to climate change. The expanded details can be found in the revised manuscript L 514-551.
Comments 2: In connection with the expansion of the discussion chapter, it is also necessary to include at least 10-15 additional items of new literature in these deliberations and of course place them in the list of references.
Response 2: Thank you for pointing this out. We agree with this comment. We have already added proper items of new literature in the list of references to tie in with our discussion. The expanded details can be found in the revised manuscript L 748-770.
Comments 3: The conclusions should be bulleted and referred specifically to the research questions. This chapter can be started with a short summary, then bulleted conclusions and at the end a few sentences about the limitations of this research and what are the plans for future research on this topic. After taking into account my suggestions, the article can be published.
Response 3: Thank you for pointing this out. We agree with this comment. We have revised the conclusions by starting with a short summary. Then we stated the limitations of this research and what are the plans for future research on this topic. The revised content can be found in the revised manuscript L 555-557 and L 592-597.
Response to Comments on the Quality of English Language
Points 1: Minor editing of English language required.
Response 1: Thank you for pointing this out. We agree with this comment. We improved the editing of English in the process of responding to specific comments.
Thank you again for your suggestions and comments.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe study examines changes in summer extreme precipitation in Southwest China from 1979 to 2021. A significant interdecadal shift was noted in the late 1990s, with a decrease from 1979-1996 and an increase from 1997-2021. Enhanced South Asian High and Western Pacific Subtropical High were identified as key factors influencing these changes. Local adaptation strategies to climate change, including technological advancements and increased community involvement, were discussed.
The suggestions for revising the paper are as follows:
1. The paper uses meteorological product data with various spatial resolutions, but the authors have not explained what method was used to unify these different spatial resolutions. Nor have they clarified the spatial resolution used in the data calculations for the paper.
2. Section 3.5 on measures against extreme precipitation is not specific enough and lacks evaluation and discussion of the effectiveness of the measures.
3. The discussion section should be strengthened, including adding explanations of the paper's important research findings, comparisons with other related studies, discussions on research uncertainties, and future development directions.
Author Response
Response to Reviewer 3 Comments
Summary
Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files.
Point-by-point response to Comments and Suggestions for Authors
Comments 1: The paper uses meteorological product data with various spatial resolutions, but the authors have not explained what method was used to unify these different spatial resolutions. Nor have they clarified the spatial resolution used in the data calculations for the paper.
Response 1: Thank you for pointing this out. In this paper, we use meteorological product data with various spatial resolutions. The spatial resolution of daily precipitation is 0.5° × 0.5, and the spatial resolution of atmospheric variables is 2.5°×2.5°, while the spatial resolution of SST is 1°×1°. Actually, it is not nesessery to unify these different spatial resolutions. We draw different figues with different meteorological product data, but we are sure that the data used in each figure has the same spatial resolution. Such operation does not affect our analysis of the trend of extreme precipitation, but also ensures that we can successfully study the atmospheric circulation.
Comments 2: Section 3.5 on measures against extreme precipitation is not specific enough and lacks evaluation and discussion of the effectiveness of the measures.
Response 2: Thank you for pointing this out. We agree with this comment. The evaluation of specific measures is a systematic and detailed process aimed at measuring the implementation effectiveness of the measures, the degree of achievement of goals, and potential room for improvement. We have added the discussion on human response to climate change to the discussion section. The revised content can be found in the revised manuscript L 537-551.
On the one hand, considering that the theme of this article is to study the changes and physical mechanisms of extreme summer precipitation in southwestern China, human adaption is the focus of our next research. Therefore, there is no evaluation of specific measures for human adaptation in this article. On the other hand, the structure of this article is relatively complete and the conclusions are scientific. If further evaluation of specific measures is added, it will make the article too long. In summary, we plan to conduct the evaluation of specific measures into future research. What we want to emphasize is that we attach great importance to your suggestions. We also hope to continue to receive your support in future research.
Thank you for your comments and suggestions.
Comments 3: The discussion section should be strengthened, including adding explanations of the paper's important research findings, comparisons with other related studies, discussions on research uncertainties, and future development directions.
Response 3: Thank you for pointing this out. We agree with this comment. We have already expanded discussion chapter by studying the mechanism of land use influence on precipitation and local human adaption to climate change. The expanded details can be found in the revised manuscript L 514-551. We also state the uncertainties of our research and future development directions in the conclusion section. Thank you for your comments and suggestions.
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsThe authors analyzed the change and mechanisms of summer extreme precipitation in Southwest China during 1979 to 2021. The study provides significant managerial implications for local governments. Here are some suggestions:
1. The author mentioned that the southeastern coastal region, the middle and lower reaches of the Yangtze River, and northern China will experience more extreme precipitation events in the future. Why did this study focus on the Southwest region?
2. It is suggested that using machine learning or multiple regression analysis to the importance of independent variables. The perform detailed mechanistic analyses on key independent variables.
3. Why did extreme precipitation, geopotential height, horizontal wind velocity, moisture flux, SAH, WPSH, etc., experience abrupt changes in 1997? It is recommended to conduct a deeper investigation into the anomalies that occurred in 1997.
4. Figure 1: Why does Figure 1 cover the period from 1988 to 2011, while the abstract states that the study period is from 1979 to 2021?
5. Figure 1: Why did extreme precipitation increase rapidly from 1989 to 1997? Besides 1997 being a turning point, it seems that 1989, 2008, and 2011 are also turning points.
6. It is suggested that the author considers using models to predict future trends of extreme precipitation in their future research (note that extreme precipitation started to decrease from 2011).
Author Response
Response to Reviewer 4 Comments
Summary
Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files.
Point-by-point response to Comments and Suggestions for Authors
Comments 1: The author mentioned that the southeastern coastal region, the middle and lower reaches of the Yangtze River, and northern China will experience more extreme precipitation events in the future. Why did this study focus on the Southwest region?
Response 1: Thank you for pointing this out. At present, a large number of relevant research have discussed the changes and physical mechanisms of summer extreme precipitation in eastern China (including the southeastern coastal region, the middle and lower reaches of the Yangtze River and northern China), but there are relatively few studies on summer extreme precipitation in southwest China. Considering that the purpose of this research paper is to provide local strategies for coping with climate change, it is necessary to study the change of summer extreme precipitation and its physical mechanism in Southwest China.
In addition, the team that the author is part of also has previous research results on summer extreme precipitation in eastern China. This study is a continuation and further development of previous research.
Comments 2: It is suggested that using machine learning or multiple regression analysis to the importance of independent variables. The perform detailed mechanistic analyses on key independent variables.
Response 2: Thank you for pointing this out. We agree with this comment.
Machine learning algorithms construct a mathematical model through training data, which can automatically adjust its parameters to minimize the error between predicted outputs and real labels. This process enables machine learning to extract hidden patterns and features from data, thereby achieving accurate prediction or classification of new data. Multiple regression analysis is a regression analysis method to study the relationship between multiple variables, aiming to describe the dependency between dependent variables and multiple independent variables by constructing a mathematical model. Both of the above methods can determine the importance of the independent variable in a physical process .
We have been able to achieve our research objectives through the use of composite analysis and linear regression analysis methods. The formation of extreme precipitation is mainly influenced by moisture flux and upward movement. The adequacy of moisture flux and the intensity of upward movement are determined by WPSH and SAH. Ultimately, the intensity of WPSH and SAH is controlled by tropical sea surface temperature and sensible heat from the Tibetan Plateau. The above physical processes do not occur simultaneously. In short, the interaction between the sea and the atmosphere determines the amount of moisture flux and the intensity of upward movement by influencing atmospheric circulation. Therefore, in the above processes, the use of composite analysis can strip the characteristics of extreme precipitation events from all precipitation features (you can find the relevant content in revised manuscript table 3 and figure 9-11). Linear regression analysis can determine the importance independent variables of each specific process (you can find the relevant content in revised manuscript table 1-2 and figure 5-8). The adoption of these two methods can meet the needs of this study, and the conclusions obtained are scientific. Our future plan is to study local human adaptation to climate change. When analyzing the importance of various elements of human society in addressing climate change, using machine learning and multiple regression methods will have significant effects.
Thank you again for your suggestions and comments.
Comments 3: Why did extreme precipitation, geopotential height, horizontal wind velocity, moisture flux, SAH, WPSH, etc., experience abrupt changes in 1997? It is recommended to conduct a deeper investigation into the anomalies that occurred in 1997.
Response 3: Thank you for pointing this out. We agree with this comment. 1997 is a very important year for extreme precipitation in southwest China. During this year, extreme summer precipitation in the southwest China experienced a change from decreasing to increasing. The direct cause of this phenomenon is the change of geopotential height, horizontal wind velocity and moisture flux. It can be seen from the Figure 5 and Figure 6 (The text content related to the figures is in the revised manuscript L 207-230 and L 237-251) that the change trend of the above meteorological elements is consistent with the change trend of summer extreme precipitation in Southwest China. The driving force of atmospheric circulation leading to the change of the above meteorological elements is that the intensity of WPSH and SAH changes from weakening to strengthening. The expanded and enhanced WPSH guides moisture flux into southwest China. At the same time, the expanded and enhanced SAH makes the ascending movement over southwest China much stronger than before. The combination of these two factors has led to an increase in extreme precipitation in Southwest China. You can find these contents in the revised manuscript L 258-263.
Furthermore, it is found that the changes of WPSH and SAH are driven by tropical sea surface temperature and sensible heat flux over the Tibetan Plateau. You can find these contents in the revised manuscript L 405-430 and L 289-305.
Comments 4: Figure 1: Why does Figure 1 cover the period from 1988 to 2011, while the abstract states that the study period is from 1979 to 2021?
Response 4: Thank you for pointing this out. According to the principle of Yamamoto method and moving t-test method, in order to obtain the abrupt point of certain climate series, we need to first select a sliding window (the sliding window in this paper is 9 years). According to the calculation formula of the above two methods, the first 9 years and the last 9 years of the climate series cannot be calculated by these two methods. Therefore, there will be periods in figure 1 where the value is 0 (1979-1987 and 2013-2021). We have chosen not to display the values for these years (because they are all 0). Such processing is only a technical operation on the drawing details and does not affect the accuracy of the conclusion.
Comments 5: Why did extreme precipitation increase rapidly from 1989 to 1997? Besides 1997 being a turning point, it seems that 1989, 2008, and 2011 are also turning points.
Response 5: Thank you for pointing this out. Climate change is affected by two factors: one is the internal variability of climate elements; The second is the influence of external factors (human or natural factors). Due to the dynamic changes of internal variability and external factors, the time series of extreme precipitation will also fluctuate. This paper uses linear regression method to find the most important change trend of extreme precipitation time series between 1979 and 1997 (showing a downward trend). During a brief period, the increase in extreme precipitation is related to the strengthening of WSPH and SAH intensity. As for the turning point, We agree with this comment. There are three kinds of mutations, the mean value mutation, variance value mutation, and trend mutation. Therefore, there may be not only one turning point for extreme precipitation series. Considering that this research is to explore the trend change of extreme precipitation, we use the Yamamoto method and the moving t-test and found that the most significant mutation point is 1997. The result is significant at 95% confidence level.
Comments 6: It is suggested that the author considers using models to predict future trends of extreme precipitation in their future research (note that extreme precipitation started to decrease from 2011).
Response 6: Thank you for pointing this out. We agree with this comment. Under the background of global warming, extreme weather and climate events had become increasingly frequent. They often resulted in substantial losses to society, because of events such as mountain floods caused by extreme precipitation, urban waterlogging, and debris flows. Thus, developing warning and prediction methods for extreme weather and climate events was urgent. For example, accurate earthquake prediction would save thousands of lives. Therefore, after REPEs were classified according to certain standards, further research and analysis of the precursor factors of each type of REPE were critical to improving disaster warning and prediction abilities. Using models to predict the future trend of extreme precipitation is an efficient and accurate method, and we will focus on this area in future research.
Thank you again for your suggestions and comments.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Comments and Suggestions for AuthorsThe author has made appropriate revisions to the paper according to the reviewer's comments, and I agree to accept this paper.
Reviewer 4 Report
Comments and Suggestions for AuthorsThe authors have made the necessary revisions. I recommend accepting the current version.
