Performance Assessment of Advanced Daily Surface Soil Moisture Products in China for Sustainable Land and Water Management

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear authors,

The article presents an innovative approach to estimating soil moisture using various satellite observations. However, the article needs to be improved, so I am giving it a major revision:

 

Title

Try to reformulate the title a little, especially the term State-of-the-Art.

 

Abstract

The abstract is written in an informative manner with an emphasis on the datasets and methodology. Nine daily surface soil moisture products based on satellite images were analyzed. However, at the end of the abstract, it is necessary to improve the abstract with a few sentences that would make the results you obtained relevant to all institutions and decision-makers.

 

Introduction

The introduction begins with basic information about soil moisture, supported by relevant references. It precisely states the three main approaches to collecting soil moisture data, as well as their advantages and disadvantages. In the second part of the introduction, studies are listed, i.e., previous research on the temporal analysis of different soil moisture products. At the end of the introduction, the aim of the study is stated: to quantify regional differences in performance, identify optimal products, and so on.

However, is there any other aim, basic or specific, that would contribute to a better understanding of the study and the applied methods?

At the end of the introduction, you can state which sections, i.e., subtitles, follow in the rest of the article.

Line 94: The map is well done, with a clear direction to the north, a scale, and a legend. However, it needs to be moved from the introduction.

Within the second section, create a subtitle ''Study area'' where you will move the map and add basic geographical, especially pedological conditions of the study area.

 

Materials and methods

Data were collected from the satellites of the European Space Agency, NASA, and the Chinese Meteorological Satellite Program, which provides a wide scope for analyzing data from different sources. Also, modern data from the Global Atmospheric Reanalysis were used.

Line 184: The table is informative. However, it is only necessary to unify the units for spatial resolution. That is, to add at least kilometers in addition to degrees, so that it would be easier for readers to compare the spatial resolutions of the data.

Line 194: It is commendable that you used data from more than 2000 measuring stations. Why was only 2018 analyzed? Was anything very different from the usual conditions and measurements at that time?

What software did you use to obtain soil moisture maps? QGIS, ArcGIS, ArcMap? It would be useful to state this.

 

Results and Discussion

The first subheading (3.1) shows nine maps. It would be useful to interpret the values ​​in more detail, in terms of which part of China recorded the lowest humidity and why, and vice versa. Based on the results, it is concluded that FY-3 products have the weakest overall performance, while SMAP L3 showed the greatest agreement with field measurements.

Line 412: You mentioned the influence of geographical and environmental factors in one sentence. Feel free to describe the influence of natural conditions in more detail because the geographical aspect is a key determinant in the distribution of soil moisture.

Line 437: In order to correctly determine the performance in dry and wet regions, it is necessary to create at least two more maps: climatological and land use. Then, overlay the obtained data with these maps.

 

Conclusions

Line 462: Somewhere in the text, you mention 2000 stations, and now 2400. Unify that.

Three main conclusions from the study are stated, as well as the primary objective that needs to be specified.

Again, at the end of the conclusion, you need to state the study's applicability to all interested organizations. The conclusion will certainly be more detailed if you also analyze the results from the climatological aspect and land use.

 

Best regards

Author Response

Thank you for your detailed notes and for sharing the supplementary materials. I have carefully reviewed the attached document and taken note of all the key points. Should there be any follow-up questions or areas requiring further discussion, I will reach out promptly.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

Attached

Comments for author File: Comments.pdf

Author Response

Thank you for your detailed notes and for sharing the supplementary materials. I have carefully reviewed the attached document and taken note of all the key points. Should there be any follow-up questions or areas requiring further discussion, I will reach out promptly.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

In the article presented automatic soil moisture content monitoring stations in China at various depth of the land. Recently there are over 2000 such stations across the China. They utilize Frequency Domain Reflactometry (FDR) technology for measurement of soil water content. When remote sensing technology is utilized, such experience can be use esspecially in agriculture and other buizneses involved in soil moisture content aspects.

In Section Conclusion it can be introduced Sub Sections describing the most important findings of the study.

Please correct as follows: Figure 2 - Mean surface...

Author Response

Thank you for your detailed notes and for sharing the supplementary materials. I have carefully reviewed the attached document and taken note of all the key points. Should there be any follow-up questions or areas requiring further discussion, I will reach out promptly.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have significantly improved and supplemented the article. The abstract now clearly acknowledges the study's applicability. The introduction has also been significantly improved, providing relevant insights into the soil moisture process. The results have been explained in more detail, as suggested. At the end of the article, the authors specifically highlight a new chapter, 4.2 Environmental Suitability and Practical Recommendations.
In the end, you just need to adapt the references to the MDPI style.
I propose that the manuscript be accepted and published.

Best regards

Reviewer 2 Report

Comments and Suggestions for Authors

None