Deriving Wheat Crop Productivity Indicators Using Sentinel-1 Time Series
, Toby W. Waine 2, Jeroen Meersmans 2,3, Paul J. Burgess 2, Giacomo Fontanelli 1,4 and Goetz M. Richter 1Round 1
Reviewer 1 Report
Dear Editor
This is a good article. The mentioned article could publish after minor revision.
Abstract
Please remove word “we” from international publications.
Abstract needs to some quantitative results. It is important to rewrite this part.
Keywords
Please use of upper case for the first word of related to each keyword.
Introduction
What is innovate the current study? Please highlight this subject.
2.1. Study area
Please add features of the study area including coordinate systems, …
Lines 86-89: please add a reference.
Figure 3.
Please replace to another figure in high quality form.
- Results
Figures 4, 5, and 6 are in queue. Please use of text and reconstruct this part.
Author Response
Thank you very much for the commets. It was very useful to improve the quality of the paper. Please find below the changes I made in the manuscript togather with the comments (in bold).
Abstract
Please remove word “we” from international publications.
Line 16: I have changed the ‘we show’ to ‘this study shows’
Line 166: change ‘we assumed logistic pattern’ to ‘a logistic model was used’
Line 291: remove of ‘we showed for data’ and ‘that,’
Abstract needs to some quantitative results. It is important to rewrite this part.
Line 28-30: I have added these sentence that displays the seasonal variation of the indicators, ‘Significant seasonal variation in the timing of peak vegetation (p = 0.042), the mid-point of growth (p = 0.037), the duration of the growing season (p = 0.039) and yield (p = 0.016) were observed and were consistent with observations of crop phenology’.
Keywords
Please use of upper case for the first word of related to each keyword.
Line 33-34: Change of the first letter in each keywork
Introduction
What is innovate the current study? Please highlight this subject.
Line 80-81: thanks for the comment. I have changed the last paragraph to clarify one of the sentences removing the ‘and that the indicators can’ and adding ‘which then’ and I would like to highlight the last paragraph in introduction lines: 77-83 as the area describing the objective of this paper. This can inform the reader about the innovation
2.1. Study area
Please add features of the study area including coordinate systems, …
Lines 86-89: please add a reference.
Line 96-97: I have added the reference of the coordinate system in the figure 1 caption ‘(coordinate system EPSG:27700)’ add I have added north arrow and 1km scale on the figure 1 to improve the reference of the coordinate system.
Figure 3.
Please replace to another figure in high quality form.
Line 122: I have changed the resolution of figure 3 to higher resolution. thanks
- Results
Figures 4, 5, and 6 are in queue. Please use of text and reconstruct this part.
Thanks of the comment. I have notice that there were some mistakes in the numbering of the figures in the version I received in contrast to what I have submitted, having two figures 3. I think that’s the problem of text refer to figures earlier. I always refer to the figures before I display them. The copy editor may suggest a better format that the one I have at the moment due to size limitations of multi-plots
Reviewer 2 Report
The manuscript is well written with sufficient results and discussions. I have some few points and clarification, which requires some minor revisions.
Point (1)--L56: “..models to simulate the backscatter interaction with vegetation and soil conditions [31–33] like the water cloud model [34].” I would suggest to include Sentinel-1 related research articles along with these state of the art literatures. You may include:
Mandal, D., Kumar, V., Ratha, D., Dey, S., Bhattacharya, A., Lopez-Sanchez, J.M., McNairn, H. and Rao, Y.S., 2020. Dual polarimetric radar vegetation index for crop growth monitoring using sentinel-1 SAR data. Remote Sensing of Environment, 247, p.111954.
Chang, J.G., Shoshany, M. and Oh, Y., 2018. Polarimetric Radar Vegetation Index for Biomass Estimation in Desert Fringe Ecosystems. IEEE Transactions on Geoscience and Remote Sensing, 56(12), pp.7102-7108.
Clauss, K., Ottinger, M., Leinenkugel, P. and Kuenzer, C., 2018. Estimating rice production in the Mekong Delta, Vietnam, utilizing time series of Sentinel-1 SAR data. International journal of applied earth observation and geoinformation, 73, pp.574-585.
Point (2)--Sec 2.2: There are very limited discussions on collection of in-situ data methods. How the yield data was collected? Is it by cutting above ground biomass over a certain area or from farmers? What types of In-situ measurements were made weekly?
Point (3)--I am not clear about the validation of results in case you have data from two seasons (2017 and 2019)?
Author Response
Thank you for the useful comments that help me to improve the manuscript. Please find below the changes I applyied as well as the comments in bold.
Point (1)--L56: “..models to simulate the backscatter interaction with vegetation and soil conditions [31–33] like the water cloud model [34].” I would suggest to include Sentinel-1 related research articles along with these state of the art literatures. You may include:
...
Line 61: Thanks for the suggestions. I have added the three papers as there are matching the paragraph. Change from ‘[31-33]’ to ‘[31-36]’ in the manuscript as well as auto-change of all reference numbers
Line 502-509: added the three references
Point (2)--Sec 2.2: There are very limited discussions on collection of in-situ data methods. How the yield data was collected? Is it by cutting above ground biomass over a certain area or from farmers? What types of In-situ measurements were made weekly?
Line 104-106: Explanation added to the text. Thanks for notice that. I clarify by adding ‘observations of phenology’ removing the ‘measurements’ and also adding information about the harvest data ‘were recorded by the harvest machinery’ removing ‘were also taken at the end of each season’ to simplify the sentence. These changes make this paragraph more explanatory about the ground data.
Point (3)--I am not clear about the validation of results in case you have data from two seasons (2017 and 2019)?
Thanks for the comment, the work in this paper doesn’t aim to create a predictive model but to display a methodology to quantify SAR time series and define productivity indicators. Therefore, we developed that quantitative methodology using three years and show the correlation including different growing seasons. The intention of this paper is to define SAR derived parameters that are sensitive to yield. As we don’t try to predict yield, the test of the sensitivity will come from applying to different sites in future work that I will collect more data from other farms. The application of this algorithm in other farms can exam the applicability of the method in the landscape level to understand the correlations in other locations.
Reviewer 3 Report
It is very interesting research with significant content and interesting to readers, which is dealing with the comparison of VH/VV ratio time series of wheat fields. The main objective of the study is to recognize the changes in backscatter values that can be related to crop growth and development and identify new SAR-derived indicators of wheat crop development and productivity that can provide insights for crop yield formation at the field scale.
A few comments were made in the attached file, just to improve the quality of the presentation
Comments for author File: 
Comments.pdf
Author Response
Thank you very much for your comments. That helped me to improve the manuscript. Please find below the changes I made:
Line 37: capital first letter for the ‘Remote Sensing’
Line 51-52: add ‘active radar sensors’ instead of SAR to distinguish from passive sensors that lack of this advantage. Also clarify the optical sensor adding the satellite name ‘(sentinel-2 satellite)’
Line 129: ‘3X3’ changed to ‘3x3’
Line 181: There were some mistakes in the numbering of the figures in the version I received having two figure 3 in contrast to what I have send. I think that’s the problem of text refer to figures earlier
Line 214: problem again with the wrong change of numbering that make the text referring much later. The copy editor may also suggest a better format due to multiplots.
