Application of the Vegetation Condition Index in the Diagnosis of Spatiotemporal Distribution of Agricultural Droughts: A Case Study Concerning the State of Espírito Santo, Southeastern Brazil

Round 1

Reviewer 1 Report

This manuscript is quite interesting and provides useful information The occurance of drounght was clearly presented with two satellite sources, and validated with the meteorological data. However, the manuscript seems to need technical improvement. 

1. The manuscript seems to need technical improvement.

(1) The text was idvided into too many small paragraphs, which frastrate the readers. 

(2) It is often unclear what the determiners such as this and that refer to. 

For example:

Does "This anomaly (L39)" mean low rainfall? And then, why the low rainfall is the least understood and the most diffcult to monitor?

"This complex climatic phenomenon (L68)" The reviewer thinks the authors did not explain about complex climatice phenomenon. 

2. VCI

L229 What does "per station" mean?

L235 in extremely dry areas -> in drier year

3. If the authors could consider the font size of the figures, it is much helpful for the printed version readers. 

4. year separator would be helpful in Figure 4. 

Author Response

Dear Reviewer,

Please see the attachment.

Best regards,

Adriano Senhorelo

Author Response File: Author Response.docx

Reviewer 2 Report

1.      Abstract: It is not very concise in the abstract and main results are not concluded in detail, and some quantitative descriptions are missing.

2.      L36: The “agricultural” should be changed to “agriculture”, and some similar mistakes please author to seriously revise.

3.      L38-L39:” it is generally characterized by the occurrence of low rainfall in a given period” Low rainfall is the cause of drought, not its characteristic.

4.      The introduction section has too many subparagraphs, it should tighten up, consolidate, and introduce your topic and innovation.

5.      Agricultural droughts are often combined with crop yield and affected area, etc. It is not convincing to evaluate the applicability of the index only by the spatial and temporal distribution of VCI in the study, and it is suggested that the authors add some crop disaster data.

6.      The lag time between VCI and LST is shown in Figure 5e for about one season, while the corresponding lag times are not shown in Figure 6a-c. Please explain this phenomenon.

7.      Temperature anomalies are not the only cause of drought. In Figure 6a-c, the area with the lowest temperature anomaly is not the area with optimal conditions. The author was asked to add the reasons behind this phenomenon.

8.      Some figures have inconsistent fonts, or obscure each other, and it is suggested to improve these details to enhance the readability of the figures. In Figure 6a-c, the drought spatialization and anomalies of temperatures would be better if the same color legend was used.

9.      L578: It is suggested that the first point and the second point of the conclusion, be merged and they are both talking about the applicability of the method.

10.   The conclusion section is a high-level summary of the article, and I think this section should add a summary of the work done in the study and its significance.

11.   Attention! the language needs to be polished.

Author Response

Dear Reviewer,

Please see the attachment.

Best regards,

Adriano Senhorelo

Author Response File: Author Response.docx

Reviewer 3 Report

1. The title should be shown clearly about the case study. Besides, the authors should replace the term "Vegetation Condition Indices" with "Vegetation Condition Index" because the paper uses only VCI.

2. Please provide more information about the pros and cons of using Vegetation Condition Indices (VCI) compared with other satellite-vegetation-based drought indicators, such as TCI, etc., and explain why the authors chose VCI for this study.

3. Please provide more information about the previous study assessing drought in Espírito Santo and clearly show the gap.

4. Please shorten contents about image processing (it is pretty standard) and focus on how to use VCI to diagnose spatio-temporal distribution of agricultural droughts and its relation with the land surface temperature (LST) anomalies and water deficiencies. Figure 2 is thus also recreated.

5. Lines 227-230: "x̅_{reference minimum} is the average of the EVI pixels, with minimums values per season, for the total series of 10 years. Finally, x̅_{reference maximum} is the average of the EVI pixels, with maximum values per station, for the total series of 10 years" should be corrected.

6. Please explain why the authors did not use correlation confections for assessing the relationship between the spatio-temporal distribution of the VCI with 1) the spatialization of Land Surface Temperature (LST) anomalies and 2) water deficiencies

7. In the section "Results and Discussion",” please clearly show this study's limitation, especially the drawback of using a short-term period (10 years) for calculating VCI in the equation (2), which made x̅_{reference maximum,} x̅_{reference minimum}, and the difference between them are not presented well enough for climatology information.

8. Please rewrite the Conclusion section to fit the aims mentioned in the Introduction part.

9. Authors need to define the abbreviation, e.g., UTM, WGS84, NOAA, etc., and make sure that the acronym is for all the terms.

10. There are so many concise paragraphs that make reader may be difficult to follow; thus, please restructure them.

 

11. Please complete proofreading should be done for the entire manuscript. 

Comments for author File: Comments.pdf

Author Response

Dear Reviewer,

Please see the attachment.

Best regards,

Adriano Senhorelo

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

All the improvements mentioned by the reviewers were implemented

Author Response

All the improvements mentioned by the reviewers were implemented

Reviewer 3 Report

Dear Authors,

 

Many thanks for your feedback. Please see my comments below in round 2 for improving the manuscript.

 

Comment 1:

Reviewer’s comment round 1: “2. Please provide more information about the pros and cons of using Vegetation Condition Indices (VCI) compared with other satellite-vegetation-based drought indicators, such as TCI, etc., and explain why the authors chose VCI for this study”.

Authors’ responses in round 1: General data were inserted in the Introduction section.

Reviewer’s comment round 2: The current introduction is not present well enough the overview of satellite-vegetation-based drought indicators for drought monitoring and why VCI (among them) is selected for these studies.

 

Comment 2:

Reviewer’s comment round 1: “3. Please provide more information about the previous study assessing drought in Espírito Santo and clearly show the gap”.

Authors’ responses in round 1: General data were inserted in the Introduction section.

Reviewer’s comment round 2: The Introduction presented not well enough about what has been done to monitor agriculture drought in Espírito Santo and why this study has been implemented.

Comment 3:

Reviewer’s comment round 1: “4. Please shorten contents about image processing (it is pretty standard) and focus on how to use VCI to diagnose spatiotemporal distribution of agricultural droughts and its relation with the land surface temperature (LST) anomalies and water deficiencies. Figure 2 is thus also recreated.”

Authors’ responses in round 1: Some of the content about image processing was a little bit reduced.

Reviewer’s comment round 2: The image processing to generate VCI and LST should be reduced more.

Comment 4:

Reviewer’s comment round 1: “8. Please rewrite the Conclusion section to fit the aims mentioned in the Introduction part.”

Authors’ responses in round 1: Done.

Reviewer’s comment round 2: The Conclusion section presents too many points that are not really related to the aim of this study. Please continue rewriting.

Comment 5:

Please double-check the explanation about VCI becaure there are some misunderstood of VCI. For example, in lines 244-248: “VCI represents the percentage of the vegetation index used, in this case of the EVI, 245 in relation to its maximum amplitude. It is employed for drought monitoring based on the assumption that vegetative vigor is affected by variations in climate. Thus, in extremely dry areas, vegetation growth is relatively slow, leading to a lower VCI value. On the other hand, a larger VCI represents conditions more suitable to plant growth [30]”.

Please be aware that (1) VCI is mostly present in the variation of weather (not climate) and (2) “in extremely dry areas” should be replaced by “in extremely dry periods.”

 

Comment 6:

Please double-check all the acronyms, e.g., the explanation of what VCI means in line 238 is not necessary.

 

Best regards,

Reviewer

Comments for author File: Comments.pdf

Author Response

All the improvements mentioned by the reviewers were implemented

Author Response File: Author Response.pdf