Satellite Soil Moisture for Agricultural Drought Monitoring: Assessment of SMAP-Derived Soil Water Deficit Index in Xiang River Basin, China
Round 1
Reviewer 1 Report
Review of “Satellite soil moisture for agricultural drought monitoring: Assessment of SMAP derived Soil Water Deficit Index in Xiang river basin, China” for the possible publication in the journal of “Remote Sensing”
In this study, the authors use SMAP and CLSMDAS data sets to investigate agricultural drought by using simple drought indices including Soil Water Deficit Index (SWDI), Percentage of Drought Weeks (PDW) and Atmospheric Water Deficit (AWD). However, the article gave no new insights into the material--my major concern is that the results shown in here were already done by other researchers but for different study areas. Also, the accuracy/error of soil moisture data should be addressed before used. Also, it seems that the authors assume that SMAP should follow CLSMDAS soil moisture product and validate SMAP against CLSMDAS. If so, why the authors are struggling to use SMAP's soil moisture data? Why not just use CLSMDAS soil moisture data?
I recommend the authors to conduct additional analysis of comparison of both SMAP and CLSMDAS data to in-situ soil moisture data.
I enjoyed this paper; however, as currently written, it is a struggle to see what the actual contribution of this paper is. Therefore, I do not believe that this manuscript is currently acceptable for publication in Remote Sensing and thus recommend major revision. I included a lot of comments in the annotated PDF file.
Something minor: all equation should be created in good quality; it is hard to read all equation shown in the manuscript.
Comments for author File: 
Comments.pdf
Author Response
Dear reviewer,
Thanks a lot for your great efforts to read through this manuscript and give very valuable comments. Here we have addressed the comments from you and the detailed description is attached.
Author Response File: Author Response.pdf
Reviewer 2 Report
COMMENTS
This is a paper on a relevant topic that lies within the scope of Remote Sensing. The objective of this study is to investigate the performance and efficiency of SMAP soil moisture used for drought monitoring in the Xiang river basin in China. The title is concise and clearly describes the contents of the paper. The abstract is also concise and complete. The presentation is clear and the language is almost always fluent and precise. The methods need some clarifications but, in general, are clearly described and could be applied by others scientists. The references are adequate but some updates are necessary.
Specific comments
- The authors have to argue on the interest of this study to demonstrate that it has a wide scope. In the present form, the study is excessively focused on a specific area, whereas the issue, agricultural drought monitoring through remote sensing, has a great interest.
- The authors should explain the methodology better and they have to clearly state that it is exportable and applicable everywhere.
- It is very important that the authors clearly underline along the manuscript that the satellite soil moisture refers to the first 5 cm of the soil. This is crucial to fully understand the results obtained. This is an approach to assess and to monitor the agricultural drought through the soil water content of the surface soil layer.
- L129: The authors should explain if that database has been validated. The references of that validation have to be included.
- L174, reference 9: The reference indicated in this point is not correct. The paper where this SWDI was proposed is as follows:
Martínez-Fernández, J., González-Zamora, A., Sánchez, N., Gumuzzio, A. (2015). A soil water based index as a suitable agricultural drought indicator. Journal of Hydrology, 522, 265–273.
- L182 and L208, reference 36: The reference indicated in this point is not correct because it is just a corrigendum. The correct reference is as follows:
Martínez-Fernández, J., González-Zamora, A., Sánchez, N., Gumuzzio, A., Herrero- Jiménez, C.M., (2016). Satellite soil moisture for agricultural drought monitoring: assessment of the SMOS derived Soil Water Deficit Index. Remote Sens. Environ. 177, 277–286.
- L188: The authors should explain why a weekly scale is the suitable temporal scale for agricultural drought monitoring.
- L190, reference 37: The reference indicated in this point is not correct. The correct reference is as follows:
Martínez-Fernández, J., González-Zamora, A., Sánchez, N., Gumuzzio, A. (2015). A soil water based index as a suitable agricultural drought indicator. Journal of Hydrology, 522, 265–273.
- L203, reference 9: The reference indicated in this point is not correct. The paper where this AWD was proposed is as follows:
Torres, G. M., Lollato, P. R., Ochsner, T. E. (2013). Comparison of drought probability assessments based on atmospheric water deficit and soil water deficit. Agronomy Journal, 105, 428–436.
- Figures 7 and 9: Units in y-axis should be included.
- L349-350: (a), (b), (c), instead of (Figure 8a), (Figure 8b), (Figure 8c).
- L352: “on agricultural drought monitoring” instead of “on drought monitoring”.
- L368: Figure 10 is cited before the Figure 9.
- L387: This figure caption should mention that rainfall is also included in this figure.
- The References section should be carefully revised to avoid some mistakes detected along the manuscript.
Author Response
Dear reviewer,
Thanks a lot for your great efforts to read through this manuscript and give very valuable comments. Here we have addressed the comments from you and the detailed description is attached.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Please find the file attached.
Comments for author File: Comments.pdf
Author Response
Thank for your advices. The uploaded file is the responses for you.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The References section has to be carefully checked and revised again.
Author Response
Thank you for your advices. The uploaded file is the responses for you.
Author Response File: Author Response.docx
Round 3
Reviewer 1 Report
I am satisfied with the reply of the authors and their proposed improvements. The manuscript reads much better now. It can be published in the present form.
