Spatiotemporal Responses of Vegetation to Hydroclimatic Factors over Arid and Semi-arid Climate

Round 1

Reviewer 1 Report

Overall, I commend the authors for their hard work on this study and I believe it is a valuable contribution to the field. I appreciate the extensive data analysis presented in this study. I feel that there is a need for more studies, such as these, that leverage remote-sensed data products to assist policy makers and land managers with valuable insights.

While I believe that this work is meaningful to share, I think there is ample opportunity to strengthen the paper so that it reaches its potential impact. My specific comments are in the table below, and my more general comments are bulleted below. I hope that these comments are valuable and help the paper to become stronger and reach its full potential. Again, excellent work.

General Comments:

·        I strongly encourage the authors to add a description of the statistical methods they used in this study. I suggest sharing the code (or a flow chart) that was employed for this analysis. I recommend clearly mentioning the temporal resolution of the dataset at each of these steps.

·        I found it difficult to interpret the results and plots in a few places. It may be helpful to clearly mention the temporal and spatial nature of the results while discussing them. I would also recommend adding units where missing.        

·        I have a general question. Can the authors share what they think about the uncertainty and bias that is inherent to remote-sensed products, and how do these effect analyses such as the ones presented in this study?

 

Specific Comments:

 

Line Numbers	Comment
28	Did you mean "Mann-Kendall's trend test"?
53	How is the current study different from Sur et al. [14]?
73	"The NDVI is used to analyze...". as you have already mentioned it's widely used in the previous line.
90-91	Can you justify using Mann-Kendall Test for this analysis? Why this test? Is this test the right statistical tool for this analysis? Are there any requirements for Mann-Kendall (MK) test to be applicable? Did you run a seasonal MK test? Why didn't you consider regional MK test? References: Hirsch, R.M. and J.R. Slack. 1984. A nonparametric trend test for seasonal data with serial dependence. Water Resources Research 20(6):727-732; Hirsch, R.M., J.R. Slack and R.A. Smith. 1982. Techniques of Trend Analysis for Monthly Water Quality Data. Water Resources Research 18(1):107-121.
103	Suggestion: consider rephrasing. What does "ill-distributed" mean? By "erratic", does it mean that the rainfall data doesn't follow a standard distribution?
104	Define "extreme values". Did you mean "hottest 99 percentile nationally"? Or did you imply if the daily temperature range is high? Or the range of yearly temperature is high?
117-118	Suggest rephrasing: "The state's water resource availability is scarce and is only 1% of the national water resources. Only 20% of the total cultivated area is irrigated."
121	There are some general comments for this section. - Include the exact data product you used. - Specify the units for the data you obtained. - Explain/elaborate the procedure you used (if any) to modify/aggregate/process the data.
129	Suggest adding a column for units of these datasets or add that information in the text. Where did you get these datasets from? MODIS MOD16A2 is not available prior to 2021. You will need to specify the products and cite the data products.
166	What does Penman-Monteith equation help calculate? PET or ET?
171-174	Can you elaborate on the procedure you used to aggregate this data?
179	Missing information. It is necessary to include a step by step explanation of how you implemented the statistical tests you used. Use relevant equations as well. It is not enough to just cite the references. You need to support the description by including the code you used and optionally a flowchart. Figure 2 is only partially helpful. What is the temporal resolution of the data on which you performed these tests? Add information on why you selected this particular test? Did you consider any other statistical tests (e.g., ARIMA, Augmented Dickey-Fuller, etc..)? If you did, please describe the selection criteria.
197	What is the spatial resolution of the analysis you performed? 30 m? Add information on temporal and spatial resolution of the results you are presenting.
201	Are these spatio-temporal max and mins?
203	missing units.
212-213	This is inaccurate. Figure 3 shows values close to 2500 mm. What is the basis for this statement? Did you mean "monthly rainfall"?
221-222	Define "homogeneous"? What is the relevance of this statement?
234a	What are "SS values"?
234b	I don't think this is accurate. What does Sen's slope represent? It's the median of the slopes. In this case, doesn't it represent the temporal median of changes in values?
245	Wrong Figure number. Figure 5 doesn't show a time series of Temperature.
270	The y-tick labels are weird. I don't think 37 deg C should be written as 370000 * 1E-4. Please fix these in Figures 8 & 9.
296	temporal ET pattern
312-314	This was already mentioned elsewhere.
403	Fix legend for Sen's slope. Make sure that the decimal point is visible. Also, you may want to use only two significant digits.
406	I did not understand this plot. Can you explain the x and y coordinates? Why do some plots have y-ticks and some do not? Notes on how to read this plot may be very helpful.
432-433	I don't understand this statement. Doesn't S > 0 mean an increasing trend? Why is it interesting?
455-456	While I agree that heterogeneity of vegetation cover and rainfall may contribute to the fluctuations, can any other factors contribute to these fluctuations? How about natural variability?
490-491	Please rephrase. This sentence is not clear.
588-589	But doesn't your analysis actually depict a positive picture over the last 21 years - increasing rainfall, ET, and NDVI and decreasing LST? Where is the need for concern based on results from this study? I don't recall discussion on influence of global climate change on Rajasthan in this study.

 

 

Author Response

Dear Reviewer,

Thank you for your insightful review. We have incorporated all the suggestions. Please find the details attached in the comments, and changes have been incorporated in the track change version.

Thanks,

Authors

Author Response File: Author Response.docx

Reviewer 2 Report

The author selected 4 factors (NDVI, LST, ET, Rainfall) to analyze the spatial and temporal variation characteristics of each factor and attempted to analyze the relationship between hydro-climatic factors and vegetative indices using correlation analysis methods. If the results were correct, it would be very useful for underpin the development of local government management decisions. But there are some problems should be solved and need major revisions.

1. In the section 2.1, the author needs to briefly describe the spatial distribution of land use in the study area and shows in the figure 1.

2. In the section 2.3, the author needs to explain why the data resampling was treated as 30m instead of 250m or 500m. What is the basis for the spatial interpolation using bilinear interpolation for all the different types of data? What is the effect on the analysis results?

3. In the section 3.1, the author may consider dividing section 3.1 into three sections, namely 3.1.1 characterization of annal year change, 3.1.2 characterization of intra-annual change, and 3.1.3 characterization of spatial change. And the author needs to put the sentence (line 220-221) into paragraph 1 to describe. In the section 3.2, the author needs to put the sentence (line266-267) into paragraph 1 to describe. Moreover, the author refers to "the wettest years" and "the driest years", but the paper does not analyze frequency of multi-year precipitation, which is inaccurate and needs to be revised.

4. In the section 3.3, the author needs to revise line 295, because the trend of increasing ET cannot be seen in Figure 13. The same problem appears in line 363 and line 371.

5. In the line 482-486, the author needs to directly explain the relationship between LST and vegetation greenness and simplify the writing style.

6. In the line 542-545, the author mentioned that uneven precipitation led to change in vegetation greenness, but the correlation coefficients analyzed in the paper were not high, please explain it.

7. In the line 577-586, this part of the text is a duplicate of the previous one, please rewrite it.

8. The core of the paper is to analyze the spatial and temporal response of vegetation to hydroclimatic factors, but this is not fully reflected. The author needs to revise section 4. In the section 4.1-4.4, the author needs to focus on explaining the reasons and accuracy of the results about the spatial and temporal characterization of the different factors. And the author needs to add section 4.5 to focus on explaining the relationship between NDVI and hydroclimatic factors.

9. The fonts of the figure need to be enlarged and standardized, please check and revise them uniformly.

10. Figure 8, 9, 18, 19 need to be modified in vertical coordinate magnitude to ensure consistency with the description in the paper.

11. The author needs to scrutinize the paper for simple errors, grammar, and simplify cumbersome statements. For example, line 64-67, 67-70, 245, 257-258, table1 et al.

 

no comments

Author Response

Dear Reviewer,

Thank you for your insightful review. We have incorporated all the suggestions. Please find the details attached in the comments, and changes have been incorporated in the track change version.

Thanks,

Authors

Author Response File: Author Response.pdf

Reviewer 3 Report

An interesting manuscript, addressing the spatio temporal variability of vegetation cover in Pakistan. However, it is not clear the result of the MK test analysis, and the full procedure adopted. I would suggest that the seasonal component of the variables could be presented.

Author Response

Dear Reviewer,

Thank you for your insightful review. We have incorporated all the suggestions. Please find the details attached in the comments, and changes have been incorporated in the track change version.

Thanks,

Authors

Author Response File: Author Response.docx

Reviewer 4 Report

The study investigates the spatiotemporal variation characteristics and relationships between NDVI and three climate factors. But the innovative aspects are not clearly evident. Here are several suggestions for improving the manuscript:

1. Please revise the abstract to highlight the most important findings.

2. The figure is too simplistic, lacking latitude and longitude information, and the explanation of the figure is inadequate.

3. In Section 2.3, there is a significant amount of repetition. It is recommended to consolidate the content.

4. In Section 2.5, it is advisable to provide a brief supplement, explaining how the correlation coefficients are calculated.

5. The results section in Part 5 can be appropriately trimmed to enhance the primary contributions of this study.

6. The emphasis of this paper should be on the response relationship between NDVI and climatic factors, but the content of the article predominantly analyzes the spatiotemporal variation characteristics of NDVI and climatic factors.

7. The changes in NDVI are influenced by various factors, and there are interactions among different factors. However, this paper only considers the bilateral relationship between climatic factors and NDVI.

Minor editing of English language required

Author Response

Please find the attached document as a response to reviewer.

Thanks,

Authors

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

NO MORE COMMENTS

Author Response

Thank you