Harmonization of Landsat and Sentinel 2 for Crop Monitoring in Drought Prone Areas: Case Studies of Ninh Thuan (Vietnam) and Bekaa (Lebanon)

Round 1

Reviewer 1 Report

Overall, this is a very good paper. It makes an important methodological contribution to the science of remote sensing applications for crop monitoring. I think the paper could be improved by adding a few sentences to the introduction more explicitly describing the paper's objective/contribution, and why it is important. Similarly, I think that the Results and Discussions section could use a little more discussion of how successful the study was in reaching its objectives, and discussing this success in relation to its application for crop monitoring. I have also outlined some specific comments below, most of which are minor grammatical issues and a few questions about figures.

Abstract

Page 1, Line 10: I think that "miss-registration" should instead be spelled as "misregistration."

Page 1, Line 13: I think that "Analysis of a pair overlapped..." should be "Analysis of a pair of overlapped..."

Introduction

Page 2, Line 26-27: The phrase "...have made satellite remote sensing played..." does not read quite right. I would recommend changing this phrase to read something like "...have allowed remote sensing to play..."

Page 2, Line 78: I think that "...speed up analyzing process." should be "...speed up the analyzing process."

Materials and Methods

Page 3, Line 101-103: In this sentence, I think the authors should add a comma after "(SR)" and after "too cloudy images," since these phrases are items in a list.

Page 4, Figure 2: I really like Figure 2. Well done! It is a nice, easily readable graphic depiction of the workflow.

Page 4, Line 124: I think that "...sates of the art..." should be "...state of the art..."

Page 5, Line 139-141: This is not a complete sentence. Please consider changing the phrasing or connecting it with the following sentence (which seems to have been the author's original intention) in order to make it a complete sentence.

Page 5, Line 158: I think that "miss alignment" and "miss registration" should be changed to "misalignment" and "misregistration", respectively.

Results and Discussions

Page 11, Figure 8. Do the a), b), and c) in Figure 8 correspond to the unimodal, bimodal, and trimodal regions indicated in Figure 7? If so, I would recommend that the authors specify as such in their in-text references to Figure 8 and/or their caption to Figure 8.

Page 11, Figure 8. What do the different colors in Figure 8 indicate? The authors explain that gray/dark pixels correspond to non-cropland, but only indicate that the bright pixels are cropland. Do the different colors of the bright pixels have any significance?

Author Response

Please see the attachment

Author Response File: Author Response.docx

Reviewer 2 Report

The paper ‘Harmonization of Landsat and Sentinel 2 for crop monitoring in drought prone areas: Case studies of Ninh Thuan (Vietnam) and Bekaa (Lebanon)’ combines innovative pre-processing technics to offer a complete cloud-based harmonization of Landsat 7, 8 and Sentinel 2 imagery. The output images and the entire code developed in Google Earth Engine (GEE) JavaScript and Python APIs are provided in free-access. An interactive example of result is also given in the GEE app.

I read this manuscript with great interest since its methodology is robust and it offers a valuable working base for future studies. The structure is satisfactory in its present form, as well as the figures. The language is clear and concise.

I highlighted in the joined document the revisions that the Authors should provide to the manuscript.

Comments for author File: Comments.pdf

Author Response

 Please see the attachment

Author Response File: Author Response.docx

Reviewer 3 Report

Major comments:

The title of the paper refers to crop monitoring, while there is nothing about that topic in the methodology section. I think general output of the study is important not only in monitoring of crop but also in other types of land cover. That’s I suggest either to remove crop monitoring from the paper title or to put more emphasis on the crop monitoring topic in methodology as well as introduction/results sections. Finally in the 3.5. section there crop monitoring is described but only in Vietnam test site. What about the second test site in Lebanon?

I suggest moving chapter 3.1 to methodology section.

The first part of 3.5 (to line 266) is also a description of methodology and should be moved.

What data did you use and how you assess the reducing of mis-regestration?

Minor comments:

In the abstract, do not use brdf acronym but the full name.

In lines 27-28 you write that there is no remote sensing data with enough spatial-temporal resolution – I suggest to rephrase that, as Sentinel-2 repetition cycle is now up to 5 days.

In line 37 you mean achieve instead of archive?

In figure 2 please enlarge the text size.

In line 141 there is no end of a sentence.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

The structure now is much better and there is more highlight on crop monitoring topic.