Analyzing Temporal and Spatial Characteristics of Crop Parameters Using Sentinel-1 Backscatter Data
Round 1
Reviewer 1 Report
SUMMARY OF THE REVIEW:
The submitted paper aims to investigate the performance of SAR data Sentinel-1 satellites for detecting the variability related to two agricultural sites in Germany. The research of the authors has a paramount importance for a sustainable use of agrifood resources, and for planning and decision-making goals to optimize field management. The manuscript has a good structure. I found few areas that need careful adjustment. The language used is perfect and very professional. For these reasons, I RECOMMEND ONLY A MINOR REVISION to this manuscript before to be considered for publication. Below, I provide more detailed comments for the authors’ consideration which I hope they will see them positively in further improving their work.
DETAILED COMMENTS:
· The title is adequate for the content of the paper.
· The paper has a good and attractive title.
· Lines 72-79 (The importance….considered at all): this section must be placed before the previous one (Lines 66-71).
· Lines 66-71 (the aim….regression models): this section must be at the last one in your introduction, keep it as it is just use First and second instead of numbers ok.
· Move Figure 1 under section 2 (tests sites).
· Rename section just 5. Results and Discussion
· Under section 5 put 5.1Temporal Variation Analysis
· Correct the number of the subsections as follows: 5.1.1 Differences between Crop Types, 5.1.2. Differences between Acquisition Settings, 5.1.3. Differences between Individual Fields, 5.1.4. Within-Field Variability (Add bullet points to the points under the subsections)
· Change the number and rephrase title of section 6 to be as follows: 5.2. Identifying Field Heterogeneity using SAR backscatter time series
· Change the number and rephrase title of section 7 to be as follows: 5.3. Regression Analysis
· Change the number and rephrase title of section 8 to be as follows: 5.4. Detecting Field Heterogeneity using Regression Analysis
· Change the number of 9 to be: 6. Conclusion
· Make sure to define ALL the acronyms form their first appearance in your paper.
· All references MUST BE CHECKED and formatted as required by MDPI, also make sure that all the references have DOI number unless it is not available.
· I suggest to cite these papers in your introduction and add them to your list of references:
Salim Lamine; George P. Petropoulos; Sudhir Kumar Singh; Szilárd Szabó; Nour-el-islam Bachari; Prashant K. Srivastava; Swati Suman. Quantifying Land Use/Land Cover Spatio-Temporal Landscape Pattern Dynamics From Hyperion Using SVMs Classifier and FRAGSTATS®, Geocarto International, 2017:1-47 http://dx.doi.org/10.1080/10106049.2017.1307460
Salim Lamine, George P. Petropoulos, Paul A. Brewer, Prashant K. Srivastava, Nour-El-islam Bachari, Kiril Manevski, Chariton Kalaitzidis & Mark G. Macklin. Heavy Metal Soil Contamination Detection Using Combined Geochemistry and Field Spectroradiometry in the United Kingdom. MDPI. Sensors 2019, 19(4), 762: https://doi.org/10.3390/s19040762
Author Response
Dear Reviewer,
we would like to thank you very much for reviewing our research article “Analyzing Temporal and Spatial Characteristics of Crop Parameters Using Sentinel-1 Backscatter Data” authored by Katharina Harfenmeister, Daniel Spengler and Cornelia Weltzien.
We carefully read your suggestions and questions and revised our manuscript accordingly.
Please find attached a point-by-point response to your comments as well as the revised manuscript with highlighted changes. Please note that one of the reviewers suggested to perform a multiple regression as additional analysis, therefore tables 3-6 and figure 17 are updated.
Sincerely,
Katharina Harfenmeister
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Authors present an interesting and decent S1 signal analysis over wheat and barley fields. Even though there is no new method developed, the presentation is very comprehensive and well organized. However, there are still some issues that need to be addressed or clarified.
For the S1 speckle filtering, the 3 by 3 window size might not be sufficient since the maximum ENL (Equivalent Number of Looks) will be as low as 9. Then, the speckle noise will not be sufficiently reduced. I suggest the author calculate the ENL.
For the 7.5 meters buffer, this might be too small compared with the 10m by 10m resolution, because the geolocation errors might exist when the RD algorithm is used in SNAP.
In section 5.2, when different acquisition settings (i.e., ASC and DES) are compared, is the incidence angle or local incidence angle being considered? since the incidence angle might have an influence on the length of the penetration path.
For the regression, multivariable regression using the combination of the VH and VV might improve the R2 and RMSE. Please add the analysis.
Author Response
Dear Reviewer,
we would like to thank you very much for reviewing our research article “Analyzing Temporal and Spatial Characteristics of Crop Parameters Using Sentinel-1 Backscatter Data” authored by Katharina Harfenmeister, Daniel Spengler and Cornelia Weltzien.
We carefully read your suggestions and questions and revised our manuscript accordingly.
Please find attached a point-by-point response to your comments as well as the revised manuscript with highlighted changes.
Sincerely,
Katharina Harfenmeister
Author Response File: Author Response.pdf
Reviewer 3 Report
This manuscript reports on a rigorous and well designed study conducted over a period of two years, with a straight forward methodology and analysis. The manuscript is well written, with results clearly presented and discussed. There are some very minor grammatical issues with respect to the use of the present tense, and with the use of the word 'respectively'- but to maintain the flow of the text, and for the sake of clarity (for the reader), it is probably best to leave as is.
In some instances, when discussing the results, I don't know if it would help to make reference to the drought/lower precipitation of 2018, which may have affected the results, eg Line 385.
If data are available, it may help to provide an estimate of the percent grain moisture content, at or near harvest, eg Lines L432, 434, 436, 654.
In terms of overall field management, to further understand the results, would it help to clarify whether most of the fields in the study where under conventional management (grown with synthetic fertilizers), under organic farming practices, or both (as the crop nutrition program, and varieties used may affect the growth, phenology, and canopy reflectance)?
Additional minor editorial suggestions are provided in the attached copy of the manuscript on Lines, 57, 128, 136, 216, 230, 232, 263, 205 (a comma), 310, 379, 399, 400, 418, 525-531, 654, 685, 723-730.
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Comments for author File: Comments.pdf
Author Response
Dear Reviewer,
we would like to thank you very much for reviewing our research article “Analyzing Temporal and Spatial Characteristics of Crop Parameters Using Sentinel-1 Backscatter Data” authored by Katharina Harfenmeister, Daniel Spengler and Cornelia Weltzien.
We carefully read your suggestions and questions and revised our manuscript accordingly.
Please find attached a point-by-point response to your comments as well as the revised manuscript with highlighted changes. Please note that one of the reviewers suggested to perform a multiple regression as additional analysis, therefore tables 3-6 and figure 17 are updated.
Sincerely,
Katharina Harfenmeister
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Thanks for the detailed clarification and addressing my concerns.
This paper can be accepted in the current form.
