Review Reports

Round 1

Reviewer 1 Report

 

The manuscript entitled “Testing the robust yield estimation method for winter wheat, corn, rapeseed, and sunflower with different vegetation indices and meteorological data” present a novel study for estimating crop yield from satellite data but with corrections based on meteorological data. The authors extend the study to four crops with an important presence in Hungary.

The study is well presented, with and extended description of the methodology. The conclusions are supported by the results

Author Response

Response to Reviewer 1 

Thank you very much for your review, we hope that with the few changes we made the manuscript is ready for the publication.

Reviewer 2 Report

In this article, Bognàr et al. presented an updated version of the 2018 paper by Kern et al. (2018, ref 16). This paper presents some models of crop yield for the same 4 different crop (winter wheat, rapeseed, maize and sunflower) with a new dataset now using data from 2000 to 2020, while the other paper used a 2000 to 2016 dataset of MODIS and weather data (FORESEE). The difference is mostly the evaluation of 16 vegetation indices in this new version, while the 2018 paper used only NDVI. There is also some evaluation of the maximum cloud cover in this paper. One of the main conclusions of the paper is the use of the GARI vegetation index for better estimation of yield in maize. While the different methods are well explained, this version of the manuscript lack a proper conclusion and also, some insight into its research goals.

Comments:

1-      Article is lacking a conclusion. This need to be corrected.

2-      The goals and hypothesis of this study should be clearly stated in the manuscript.

3-      Could the authors use either corn or maize through the manuscript.

4-      Could the authors add the number of data points used for each analysis in the Mat & Methods.

5-      Line 42, Ref. 2 could be changed to a better review on vegetation indices

6-      Figure 1 is missing different elements (scale, geographical information). It is also unclear what is the NUTS-3 level shown. I believe the authors wanted a figure similar to the Figure 1 of Kern et al. 2018 (?).

7-      Line 505, Refrain from using “not much worse”.

8-      Line 521, “so the use of 90% cloud cover criteria seems expedient here”. It is unclear, from the presented results, how the authors come to this conclusion (?). Would a threshold of 85% be acceptable?

9-      Could the authors clarify to which crop corresponds the HSCO data of figure 6? Is it aggregated data for the four different crops? Since the different crops share different phenology and growth rates, it is unclear how informative this figure is.  

10-   Although Figure S3 is complex, I feel like it belongs in the main manuscripts since it really clarify the method used by the authors since it is sometimes unclear in the manuscript what is the meteo. correction applied.

11-   In the Table S2 and Figure 5, the authors used 30% cloud cover, instead of the 10% max. Could the authors explain why this level was chosen (line 521)?

12-   Since the authors use MODIS data, how do their models apply to the other European countries?  

Author Response

Response to Reviewer 1 Comments

Thank you very much for your detailed comments. All of your suggestions were accepted, and we hope, that with these changes the manuscript is ready for  publication.

Point 1: Article is lacking a conclusion. This need to be corrected.

Response 1: A new Conclusions chapter was added.

Point 2: The goals and hypothesis of this study should be clearly stated in the manuscript.

Response 2: We agree with the importance of the explicit mentioning of the aims. Although the aim of the present study was indicated in the submitted manuscript (starting from line 67) originally as well. Now we extended it with an additional thought.

Point 3: Could the authors use either corn or maize through the manuscript.

Response 3: "Maize" was changed to "corn".

Point 4: Could the authors add the number of data points used for each analysis in the Mat & Methods.

Response 4: In the country-level analysis 21 points were used (as 21 years were investigated), in the county-level analysis 21*19=399 data were used (21 years, 19 counties). These numbers are now also indicated in lines 373 and 493.

Point 5: Line 42, Ref. 2 could be changed to a better review on vegetation indices

Response 5: We changed this reference to Khanal et al. (2020).

Point 6: Figure 1 is missing different elements (scale, geographical information). It is also unclear what is the NUTS-3 level shown. I believe the authors wanted a figure similar to the Figure 1 of Kern et al. 2018 (?).

Response 6: The missing elements were added. However, the different counties (at NUTS-3 level) are not mentioned literally, results are presented based on the county-level investigations  as well (Fig 12). Therefore, we found it important to indicate the 19 Hungarian counties, to present their approximate sizes.

Point 7:  Line 505, Refrain from using “not much worse”.

Response 7: The sentence was corrected.

Point 8: Line 521, “so the use of 90% cloud cover criteria seems expedient here”. It is unclear, from the presented results, how the authors come to this conclusion (?). Would a threshold of 85% be acceptable?

Response 8: We inserted the reference to Figure S5, which shows, that in this case the 90% cloud cover criteria gave the best result. (The 85% cloud cover threshold was not investigated, only the 80% and 90%.)

Point 9: Could the authors clarify to which crop corresponds the HSCO data of figure 6? Is it aggregated data for the four different crops? Since the different crops share different phenology and growth rates, it is unclear how informative this figure is.  

Response 9: We completed the figure caption ("differences between estimated and HCSO country-level corn yield data")

Point 10: Although Figure S3 is complex, I feel like it belongs in the main manuscripts since it really clarify the method used by the authors since it is sometimes unclear in the manuscript what is the meteo. correction applied.

Response 10: This figure was moved to the main manuscript.

Point 11: In the Table S2 and Figure 5, the authors used 30% cloud cover, instead of the 10% max. Could the authors explain why this level was chosen (line 521)?

Response 11: In the case of corn the 30% cloud cover criteria gave the best result, we inserted the reference to Figure S3 in the Discussion chapter.

Point 12: Since the authors use MODIS data, how do their models apply to the other European countries?

Response 12: A sentence was added in the new Conclusions chapter (line 619).