Space–Time Characterization of Extreme Precipitation Indices for the Semiarid Region of Brazil

Round 1

Reviewer 1 Report (Previous Reviewer 1)

Comments and Suggestions for Authors

The responses you've provided generally address the concerns raised in the first round. However, there are a few points worth considering:

While some parts of the response acknowledge the reviewer's concern, it would benefit from providing additional justification for the robustness of the IMERG V6 database over a 20-year period, especially given the emphasis on longer observational periods for trend analysis in the referenced studies. Consider explicitly analyzing how the IMERG V6 20-year timeframe trends align with observational periods for trend analysis and why it is appropriate in this context.

 

The response addresses the concern regarding the scientific contribution and highlights the relevance of the results for the SAB region. To further strengthen this study, consider providing more specific details about how your study contributes to existing knowledge in the field. Discuss the practical implications of your findings and how they extend or challenge existing literature.

 

Overall, it's crucial to ensure that your responses not only address the concerns raised by the reviewer but also provide sufficient evidence and context to support the validity and significance of your study.

 

Additionally, we have a query about researchers promoting the product!!, express why the chosen product was deemed suitable for your research despite potential concerns. what the improvements or advancement since the publication of your previous article "40". Explain how potential issues or errors identified in the previous article have been addressed in the current study, When I reviewed the previously published article  by the same researcher, the error indicators were fairly high. How can I base trend results on high error rates that greatly distort the time trend, Other than it is  very short series."

Comments on the Quality of English Language

Moderate editing of English language required

Author Response

Point 1: “While some parts of the response acknowledge the reviewer's concern, it would benefit from providing additional justification for the robustness of the IMERG V6 database over a 20-year period, especially given the emphasis on longer observational periods for trend analysis in the referenced studies. Consider explicitly analyzing how the IMERG V6 20-year timeframe trends align with observational periods for trend analysis and why it is appropriate in this context.” 

Response 1:

According to the WMO, climatological studies typically utilize data series of at least 30 years. However, for the present study, utilizing IMERG V06 data, there is no availability of data for this period, with only a total of 20 years. Rain gauge data could potentially address this need by providing a more extensive temporal series. However, in this study, the intention was to conduct spatial analyses covering the entire semiarid region of Brazil, which would not be feasible with the current distribution of rain gauges. 

Furthermore, in the work of Reis et al. (2020), conducted with observational data in an area within the semiarid region of Brazil, similar results to those found in the present research were observed, both regarding precipitation and trends. In this work, the authors used data from Xavier et al. (2015), spanning from 1980 to 2013, totaling 33 years. Therefore, it is confirmed that the 20 years of IMERG data are adequate to achieve the objective of obtaining a spatial distribution of extreme indices for the semiarid region, as well as conducting trend analysis. It is worth noting that this trend cannot be extrapolated to other periods, being a valid observation only for the studied period. Additionally, it was shown in the article by Dos Santos et al. (2022) that IMERG data are reliable for evaluating precipitation extremes in the study region. The modifications were made in the following lines:

 

Line 238 to 242 : It is important to emphasize that, although the study period of 20 years does not meet the conventional 30-year criterion for climatological analyses, it is sufficient to unveil significant trends in the indices of extreme precipitation in the semiarid region. The use of IMERG data, a satellite product widely recognized and recommended for meteorological and climatic studies, ensures the reliability of our analyses.

 

Point 2: “The response addresses the concern regarding the scientific contribution and highlights the relevance of the results for the SAB region. To further strengthen this study, consider providing more specific details about how your study contributes to existing knowledge in the field. Discuss the practical implications of your findings and how they extend or challenge existing literature.

Response 2: 

Thank you for the considerations. We are considering providing more details about the study's contribution to the analyzed region by incorporating the following information into the article text, in the highlighted lines below:

Line 135 to 155 : The SAB study area , there is a region of economic significance for Brazil, notably within encompassed by three of the four states that make up the region known as MATOPIBA (Maranhão, Tocantins, Piauí, and Bahia). Thus, the scope of this study includes a significant portion of MATOPIBA, which has a humid tropical climate with a dry austral winter and exhibits positive and negative trends indicating alterations in local precipitation patterns [44]⁠. This territory is recognized as an area of increasing interest for investments in Brazilian agribusiness, as documented by various sources [45]–[47]⁠.

However, beyond the economic aspect of the region, there are other fundamental reasons that justify conducting this research in the SAB. Considering it as a region vulnerable to meteorological phenomena due to its tropical nature [48]⁠, it is crucial to obtain results aimed at practical solutions. These findings should contribute to the formulation of public policies and scientific analyses that enhance understanding of how climatic adversities, such as extreme precipitation, can impact the health of the local population, for instance. Prolonged exposure to such conditions can result in lasting modifications to people's health status [49]–[51]⁠. Another significant outcome arises from continuous improvements in product performance, which refine the parameterizations of meteorological models in successive iterations. These enhancements enable more efficient precipitation measurements across virtually all spatial and temporal scales [52], [53]⁠.

 

Point 3: “Additionally, we have a query about researchers promoting the product!!, express why the chosen product was deemed suitable for your research despite potential concerns. what the improvements or advancement since the publication of your previous article "40". Explain how potential issues or errors identified in the previous article have been addressed in the current study. ”

Response 3: 

The IMERG database is subject to continuous updates. With the transition to its latest version, IMERG V07, processing began in July 2023 and was completed in August of the same year, with finalization in December 2023. In this study, we have chosen to continue using IMERG V06, the same version employed in Dos Santos et al., 2022. This decision is due to the lack of sufficient time to reprocess the data from the most recent version. This is because these results are part of my doctoral research, which needs to be completed soon. However, we believe it is relevant for future work to compare the two versions for the area we are analyzing to determine if there have been significant changes between them.

In the article text, we provide important references demonstrating the effectiveness of IMERG V06, thus eliminating the need to reprocess the data with the latest version. We outline the modifications with their respective citations along the highlighted lines below:

Line 92 to 109: Launched in early 2015, IMERG  [34]⁠⁠, amalgamating data from the National Aeronautics and Space Administration (NASA) with the satellite mission The Tropical Rainfall Measuring Mission (TRMM) [34], proved to be highly efficient in estimating precipitation in tropical regions. This effort also includes contributions from the Japanese Aerospace Exploration Agency (JAXA) and the Global Precipitation Measurement (GPM) satellite, launched in 2014, showcasing a successful collaboration in advancing precipitation measurement technologies. 

Building on these advancements, IMERG represents an advancement compared to TRMM in various aspects: it combines data from multiple satellites, boasts higher spatial and temporal resolution, incorporates advanced techniques that enhance precision, and facilitates a more effective visualization of meteorological data. According to [35]⁠, who assessed the progression of IMERG versions, it is possible to discern enhancements with each iteration. Quality indices indicate improvements in the product, including better calibration. This suggests that in the SAB region, there are areas situated between regions with measurement networks considered good to excellent, and in other areas, there is a bias adjustment consistent with the observations in surface data. Nevertheless, these regions will still require further enhancements, which will be implemented with subsequent versions released over time.

 

Point 4: When I reviewed the previously published article  by the same researcher, the error indicators were fairly high. How can I base trend results on high error rates that greatly distort the time trend, Other than it is  very short series."

Response 4: 

In our previous study, Dos Santos et al., 2022, where we employed a high volume of statistical analyses for the 12 extreme precipitation indices, we identified that only one index showed an error, the SDII. Within the other analyzed indices, we obtained satisfactory results for the studied region. Trend analyses for the same indices support the findings of cited research such as Reis et al., 2020.

The results indicate greater agreement with locally observed data on a daily basis, compared to other studies (Reis et al., 2020; Batista et al., 2024). Additionally, the IMERG V06 estimates used in the study demonstrate enhanced accuracy concerning extreme precipitation. These pieces of information have been incorporated into the article text in the lines below:

Line 116 to 127 : With results similar to, and more recent than, those of [42]⁠, where the estimation capacity of data from IMERG version 6 satellite was evaluated over a river basin predominantly located in the SAB, using IMERG Early, Late, and Final products for extreme precipitation, it was also found that the final IMERG estimates, used herein, exhibit better agreement with in situ data on a daily scale, as previously demonstrated by [43]⁠. In this evaluation, areas with underestimated or overestimated precipitation were observed according to the indices, with certain areas potentially influenced by the predominant cloud type in the region, a result supported by the research conducted by [39]. These two studies, particularly, underscored the limited efficacy ofIMERG products as per the Simple Precipitation Intensity Index (SDII). Although there is potential for error, the analyses remain important as they align with the majority of the other 11 extreme precipitation indices analyzed, which yielded positive outcomes.

Reviewer 2 Report (Previous Reviewer 3)

Comments and Suggestions for Authors

The authors substantial improve the manuscript after revisions. Still the authors can perform some minor revisions:

The policy implication of the study can be included at the end of the abstract.

The caption of figure 1 (horizonal and vertical)....lat and log can be removed since the latitude and longitude is indicated on the map.

Results and discussion is sound. The conclusion is also well written.

Author Response

Point 1: “The policy implication of the study can be included at the end of the abstract.”

Response 1: 

We provide the conclusion in the abstract, which reiterates the study's importance, as well as highlights its practical implications and recommendations for public policies. This leaves the abstract with a more effective conclusion that substantiates the research's impact and implications. The added lines to the text are highlighted below:

Line 31 to 34 : The study is important for highlighting and considering the impacts of changes in precipitation extremes in the Semiarid region of Brazil. Based on the obtained results, we advocate the implementation of public policies to address challenges, such as incorporating adaptations in water resources management, sustainable agricultural practices, and planning for urban and rural areas.

 

Point 2: “The caption of figure 1 (horizontal and vertical)....lat and log can be removed since the latitude and longitude is indicated on the map.”

Response 2: Correction accepted and carried out

Reviewer 3 Report (New Reviewer)

Comments and Suggestions for Authors

The purpose of the work “Space-time characterization of extreme precipitation indices for the Semiarid region of Brazil” is to study the characteristics of regional trends in extreme indices associated with precipitation in the semi-arid region of Brazil.

The study region is interesting because it is both a semi-arid zone and the region with the highest rainfall in the world.

The research paper seems very relevant, since in recent years there has been a steady increase in the activity of extreme weather events associated with precipitation. This can be either an increase in precipitation intensity or the onset of severe droughts. In a region like Brazil, with significant elevation changes and varied climate conditions, extreme weather events can occur in both directions. The consequences of such a trend in the dynamics of these phenomena can be extremely negative for the environment and various areas of activity.

The study used daily precipitation data from the IMERG V06 product, covering the period from 1 January 2001 to 31 December 2020. Although a 30-year period (WMO) is recommended for climate change studies,  I believe that to obtain representative results for determining climate extremes in a specific territory, this series length is quite acceptable.

Analysis of spatial and temporal trends in precipitation patterns was carried out using twelve extreme precipitation indices, the reliability of the identified changes was confirmed by the nonparametric Mann-Kendall test and Sen's slope.

The article is well structured: a brief geographical description of the study area is given with a map of the region (Figure 1), the source of data is given (online platform), a brief description of 12 precipitation extremeness indices is given, and a small theory of statistical analysis.

The research results are presented in the form of illustrations (Figures 2-5). In my opinion, for greater clarity, the values of the identified trends could be presented in the form of a summary table.

Based on the analysis of all considered indices, it was found that the peripheral regions of the semi-arid regions of Brazil, especially in the northwest and extreme southern regions, demonstrate a higher intensity and frequency of extreme precipitation compared to the central part of the region.

However, the results of the observed trends show that the region with the highest number of consecutive dry days is the western region, where positive trends were observed during the analyzed period 2001-2020. At the same time, in the eastern part of the region, a contrasting scenario with negative trends was observed (a decrease in the number of dry days).

The results of such studies are very important because they can be used to develop an algorithm for scientific, methodological and information services to ensure solutions to the problems of adapting the economy to climate change and reducing the risks associated with extreme weather events.

I would like to note the voluminous and informative number of cited works, 70% of the cited references are publications over the past 5 years. For the stated purpose, the research was carried out at a high level, the paper was fully disclosed. The article is recommended for publication in the journal.

Author Response

Point 1: “The research results are presented in the form of illustrations (Figures 2-5). In my opinion, for greater clarity, the values of the identified trends could be presented in the form of a summary table.

Response 1: 

We understand that values presented in tables offer better visualization and detail of the results. However, the objective of this study is to identify and characterize areas with the most significant trends. Therefore, the most suitable way to present the results is through maps that highlight this spatial distribution.

Round 2

Reviewer 1 Report (Previous Reviewer 1)

Comments and Suggestions for Authors

Given the numerous limitations inherent in the study due to uncertainties in trends and the accuracy of the IMERG V06 product, it is recommended to dedicate a separate section addressing the scientific and practical constraints associated with using IMERG V06 for evaluating indicators of extreme events.

 

Comments on the Quality of English Language

Moderate editing of the English language is needed, as there are several typos that should be corrected

Author Response

Point 1: Given the numerous limitations inherent in the study due to uncertainties in trends and the accuracy of the IMERG V06 product, it is recommended to dedicate a separate section addressing the scientific and practical constraints associated with using IMERG V06 for evaluating indicators of extreme events.

Response 1:  

Dear Reviewer,

Thank you for your new suggestion; however, we chose to incorporate the modification into an existing section rather than creating a new one. Therefore, we have integrated it into the article, including information about the limitations of the product used in the Materials and Methods section. Given this adjustment, we believe it is appropriate to also include it in the Conclusions section. The respective changes are presented here in this response:

Materials and Methods, topic 2.2.1

Lines 205 a 224: Although IMERG has been used in numerous studies over the years, demonstrating its quality in estimating precipitation [20, 26, 29, 32, 36, 39], the product, IMERG V06, still has some points to be improved. [39] suggested a tendency towards underestimation along the coasts of Northeastern Brazil (NEB) and corroborates with [29], which reports the overestimation of delivery intensities by the IMERG product, especially in more intense events. This underestimate is related to the difficulty in estimating the occurrence of warm clouds [16]. On the other hand, Gan et al. (2021) identify cases of overestimation of IMERG V06 when compared with a previous version of the satellite's daily and monthly product, indicating the need for ongoing improvements.In this regard, the comprehensive literature review conducted by [53] sheds light on IMERG's variable performance across different climatic and geographical conditions. Analyses indicate that IMERG tends to be more accurate in humid regions, while facing challenges in semi-arid and arid areas, as well as in complex terrains and mountainous regions. Temporal aggregation significantly enhances IMERG's precision, suggesting superior performance in monthly and annual analyses. Notably, [53] emphasize IMERG's capability to capture patterns and variability of extreme precipitation, despite certain limitations in accurately estimating high-intensity events. This aspect is crucial for the analysis of temporal trends in extreme precipitation indices, with its continuous development and improvements in each new version reinforcing its role in understanding extreme precipitation events, making substantial contributions to climatology and hydrology.

Conclusions

Lines 499-507: After all, recent studies highlight the complexity and limitations of remote sensing precipitation estimation. The search for more accurate and reliable methods continues to be a priority, especially given the growing challenges related to climate change and water resources management. That is, an accurate assessment for the use of applications is crucial. It is noteworthy that we are currently using the IMERG product in its sixth version and are transitioning towards a more recent version, IMERG 07, launched in December 2023. Therefore, the importance of this work is highlighted so that it is possible to make a comparison between versions 6 and 7 for the study area, tracking the evolution of IMERG.

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

Comments and Suggestions for Authors

In summary, while IMERG offers valuable insights into global and regional precipitation patterns, its limitations in spatial and temporal resolution, calibration issues, and the complexity of extreme events make it challenging to provide accurate analyses of extreme precipitation indices and their linear trends. For in-depth studies on extreme precipitation events and trends, researchers often rely on a combination of satellite data, ground-based observations, and high-resolution climate models to gain a more comprehensive understanding. Typically, analyses of temporal trends in rainfall indicators based on observational evidence span periods of no less than 30 years or more to ensure robust results. Despite the precision of these analyses, uncertainties still exist in interpreting changes attributed to climate change.

Therefore, utilizing only 20 years of IMERG data might not yield significant insights into precipitation patterns over such a relatively short duration. If this data is of high accuracy, it is crucial to meticulously compare it with observed data to ensure reliability. Without this careful comparison, the study's findings may lack practical utility in establishing conclusive results.

Considering the limitations mentioned above, I do not recommend publishing this manuscript. Furthermore, the scientific contribution in this manuscript appears to be limited.

Comments on the Quality of English Language

Moderate editing of English language required

Author Response

Point 1: “In summary, while IMERG offers valuable insights into global and regional precipitation patterns, its limitations in spatial and temporal resolution, calibration issues, and the complexity of extreme events make it challenging to provide accurate analyses of extreme precipitation indices and their linear trends. For in-depth studies on extreme precipitation events and trends, researchers often rely on a combination of satellite data, ground-based observations, and high-resolution climate models to gain a more comprehensive understanding. “

Response 1:  Page de 81 to 88 - The integrated multi-satellite retrievals for global precipitation measurement (IMERG) product version 06 stands out in estimating precipitation among existing products [30–33] . Recently, [34] evaluated this iteration of IMERG alongside five additional remote sensing products, and IMERG demonstrated superior performance. Similar to [34], other studies conducted globally and in Brazil have evaluated and validated this database, highlighting its provision of precise precipitation estimates and robust statistical outcomes, exhibiting good performance when compared to other versions of IMERG [24,35–39], including the SAB region [39], where precipitation extremes were assessed using IMERG V6 data.

Point 2: “Typically, analyses of temporal trends in rainfall indicators based on observational evidence span periods of no less than 30 years or more to ensure robust results. Despite the precision of these analyses, uncertainties still exist in interpreting changes attributed to climate change.

Therefore, utilizing only 20 years of IMERG data might not yield significant insights into precipitation patterns over such a relatively short duration. If this data is of high accuracy, it is crucial to meticulously compare it with observed data to ensure reliability. Without this careful comparison, the study's findings may lack practical utility in establishing conclusive results.”

Response 2: The 20-year period of data is efficient for carrying out trend analyses, being very useful in identifying patterns over time. The database is robust, as it has grid point resolution and has already been validated in previous research carried out by the same authors.

Point 3: “Furthermore, the scientific contribution in this manuscript appears to be limited.”

Response 3: Page de 152 to 156 - The IMERG V6 database is highly recommended for research purposes, particularly within the SAB region, given its minimal occurrence of statistical errors as presented by [40]. This aspect is especially crucial as it could lead to reduced climate-related risks for agriculture, urban planning, and water resource management.

The results are relevant to the region for reducing climate risks for agriculture, urban planning and water resources.

Reviewer 2 Report

Comments and Suggestions for Authors

General comments:

This manuscript is devoted to analysing extreme precipitation events in a wide area of Brazil, namely the vast semiarid climate region. A number of well-established indices are selected for this purpose. Their spatial distribution is mapped and a trend analysis is applied to identify climate change signals. Although the pertinence of this study is quite apparent for several socioeconomic sectors in Brazil (e.g., agriculture, forestry and hydropower generation), the topic deserves further development. Therefore, I recommend some major revisions in my specific comments below before considering its publication.

Specific comments:

1. Ln 21: "The indices that best characterized the region were the annual total precipitation and the consecutive dry days...". Please provide a justification based on scientific evidence of this statement.

2. The satellite-based dataset used for precipitation (IMERG V06) needs to be validated against observations in the study area. The authors mention previous studies in Ln 71-79, but a more in-depth validation should be carried out specifically for precipitation extreme events, which are the main focus of this study. Gridded datasets based on weather stations are available over Brazil (e.g., from the EU Copernicus platform), which will allow a thorough comparison and validation and, eventually, bias correction. In fact, some issues arise from IMERG in the target area. As an illustration, the text from Ln 238-256 refers to the effects of the Sobradinho reservoir on the local climate. These are conjectures that do need to be accurately demonstrated with local station data, as satellite-based precipitation estimations commonly suffer from biases related to water surfaces and other land cover features. This is a major concern that needs to be convincingly addressed.

3. The methodology does not bring any innovation. The description of the Mann-Kendall test and Sen´s slope is unnecessary since they are widely used in climate research. A reference would be sufficient. The significance level of 10% is too low. 5% is preferable. The mathematical expressions show several typos (e.g., Eq. 2 "Se"). Also, the symbols in the text are not in the same format as in the equations.

4. The results from the trend analysis for such a short period (2001-2020, 20 years) are not statistically robust. According to the WMO, this is the minimum period to define a given climate. Thus, for trend assessments, much longer periods need to be considered. This limitation again highlights the need to use an alternative dataset for the objectives of the study.

5. The results section is too descriptive. A deeper discussion of the outcomes should be provided, such as the relationship with local weather types and their potential modifications. The authors can use either previous references for a more detailed discussion (in a new Discussion section) or provide some additional analysis of atmospheric variables (e.g., geopotential height, temperatures, vorticity and wind).

6. Please change "rainfall" to "precipitation" throughout the text.

7. Section 2.4 should be "Statistical analysis" or similar.

8. Ln 232-234: This sentence should be in the Introduction section.

9. Ln 290-291: Why mentioning Nepal here? The climatic trends are not expected to be related between Brazil and Nepal, though they can have similar signals and magnitudes. Other studies for the same region, or covering it, should be referred to instead.

10. The last paragraph of the Conclusions may have been written by mistake. Please remove.

Author Response

Point 1. Ln 21: "The indices that best characterized the region were the annual total precipitation and the consecutive dry days...". Please provide a justification based on scientific evidence of this statement.

Response 1: Page 22 to 29 - Based on the analysis of all considered index, it is observed that the peripheral areas of the SAB, especially in the northwest and extreme south regions, exhibit higher intensity and frequency of extreme precipitation events compared to the central portion of the area. However, a negative trend in the intensity of these events is noted in the north, while positive trends are identified in the south. Regarding the frequency of these extreme events, there is a predominance of negative trends in most of the region, with an increase in the occurrence of consecutive dry days notably throughout the western region of the SAB. The average total precipitation index was above 1000 mm to the north of the SAB, whereas in the central region, precipitation averages were predominantly below 600 mm, with rainfall intensity values ranging between 6 to 10 mm/day. Over the span of 20 years, the region underwent an average of 40 consecutive dry days in certain localities.

Point 2. “The satellite-based dataset used for precipitation (IMERG V06) needs to be validated against observations in the study area. The authors mention previous studies in Ln 71-79, but a more in-depth validation should be carried out specifically for precipitation extreme events, which are the main focus of this study. Gridded datasets based on weather stations are available over Brazil (e.g., from the EU Copernicus platform), which will allow a thorough comparison and validation and, eventually, bias correction.“

Response 2 : Reply to reviewer 1 in point 2

Point 2.1: “In fact, some issues arise from IMERG in the target area. As an illustration, the text from Ln 238-256 refers to the effects of the Sobradinho reservoir on the local climate. These are conjectures that do need to be accurately demonstrated with local station data, as satellite-based precipitation estimations commonly suffer from biases related to water surfaces and other land cover features. This is a major concern that needs to be convincingly addressed.”

Response 2.1: The regions of bodies of water are the areas in which satellite products are best represented, as shown in the results of the references cited between lines 81 to 88.

Point 3. “The methodology does not bring any innovation. The description of the Mann-Kendall test and Sen´s slope is unnecessary since they are widely used in climate research. A reference would be sufficient. “

Response 3: We understand that the permanence of the equations is important for a better understanding of the methodology.

Point 3.1: “The significance level of 10% is too low. 5% is preferable. The mathematical expressions show several typos (e.g., Eq. 2 "Se"). Also, the symbols in the text are not in the same format as in the equations.”

Response 3.1: When carrying out the test with %5 significance, we identified few points and with 10% we can better see the regions with positive or negative trends. Typing errors in equations have been corrected.

Point 4. “The results from the trend analysis for such a short period (2001-2020, 20 years) are not statistically robust. According to the WMO, this is the minimum period to define a given climate. Thus, for trend assessments, much longer periods need to be considered. This limitation again highlights the need to use an alternative dataset for the objectives of the study.”

Response 4: The article is not a climatological analysis, the period used is the period of data available for the analysis and is the same used for the first part of this research, already published.

Point 5. “The results section is too descriptive. A deeper discussion of the outcomes should be provided, such as the relationship with local weather types and their potential modifications. The authors can use either previous references for a more detailed discussion (in a new Discussion section) or provide some additional analysis of atmospheric variables (e.g., geopotential height, temperatures, vorticity and wind).”

Response 5: Analysis of atmospheric variables, that is, synoptic analyzes are not necessary for the main objective of the article.

Point 6. “Please change "rainfall" to "precipitation" throughout the text.”

Response 6: Correction accepted and carried out.

Point 7. “Section 2.4 should be "Statistical analysis" or similar.”

Response 7: Correction accepted and carried out.

Point 8. “Ln 232-234: This sentence should be in the Introduction section.”

Response 8: Correction accepted and carried out.

Point 9. “Ln 290-291: Why mentioning Nepal here? The climatic trends are not expected to be related between Brazil and Nepal, though they can have similar signals and magnitudes. Other studies for the same region, or covering it, should be referred to instead.”

Response 9: Correction accepted and carried out. Studies carried out in the area we are analyzing and in its surroundings were cited.

Point 10. “The last paragraph of the Conclusions may have been written by mistake. Please remove.”

Response 10: Correction accepted and carried out.

Reviewer 3 Report

Comments and Suggestions for Authors

This manuscript is aimed to characterize regional trends of extreme indices associated with rainfall in the Semiarid region of Brazil. 

Under abstract section: The authors should introduce some results.

Introduction:  To enhance the quality as academic paper, author must identify the theoretical aspects in introduction section to strengthen the importance of this research.

Results and discussion section is well written.

The conclusion should be improved. The authors can conclude their results without using numerical values. 

Author Response

Point 1. “Under abstract section: The authors should introduce some results.”

Response 1: Correction accepted and carried out.

Point 2. “Introduction:  To enhance the quality as academic paper, author must identify the theoretical aspects in introduction section to strengthen the importance of this research.”

Response 2: Correction accepted and carried out.

Point 3. “Results and discussion section is well written.”

Response 3: Correction accepted and carried out.

Point 4. “The conclusion should be improved. The authors can conclude their results without using numerical values.”

Response 4: Correction accepted and carried out.