Synergistic Potential of Optical and Radar Remote Sensing for Snow Cover Monitoring

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper explored the synergistic potential of optical and radar remote sensing for snow cover monitoring over the main snow-dominated montane regions of the Iberian Peninsula. There are some questions the authors may answer or consider before this manuscript goes for careful revision.

1. Please specifically elaborate on the innovations and contributions of this paper in the introduction section.The comparison and combination of optical and radar cannot be considered a significant innovation, and innovative work needs to be carried out from a technical perspective.

2. Why is the average PSCPI calculated with an interval of 10m elevation? It suggests to  supplement the elevation map of the research area.

3. In Sec. 3.2 Methods, the fusion criteria for the two types of optical and radar is simple. How to ensure the validity of analysis results if there is a problem with the accuracy of the original product? How to determine various PSCPI thresholds?

4. Please add an explanation in the text for the terms "LUMPED&T" and "code" in Figure 2 of the methodology section.

5. In Figure 7(a), the contribution from HRS&I SWS (wet snow) suddenly decreases in May. Please provide an explanation for this in the paper.

6. The dates in Figure 8 do not match the dates described in the text. 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Some minor comments:

Line 79: Please add the full name of PSCPI

Line 127: NDIS is a unitless variable. It ranges from -1 to 1. Please this variable description through whole paper.

Section 3.1.3: please add the data available website.

Line 167 and Fig. 2: Please see the first comment.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

I found the manuscript interesting, but it requires major revisions before it can be considered for publication. My detailed comments are as follows:

• L16, L207, and L407: Clarify whether "information" or "data" is intended.
• L17: Specify which method is optical and which is radar.
• L21 and L31: Define SAR before using the abbreviation.
• L30: Remove "(9-15%)" for clarity.
• Abstract: Please explain how the two methods complement each other or suggest which has a potential advantage.
• Ensure that all acronyms are defined when first introduced, e.g. L79 (PSCPI) and L86 (AEMET).
• Define "wet snow," "dry snow," and briefly explain the C and X bands the first time they are mentioned.
• The introduction lacks literature review. Please incorporate recent research in snow hydrology and remote sensing.
• Fig. 1: Consider adding the spatial elevation of the sites in the figure.
• Fig. 2 is not referenced in the text. In the Methods section, consider adding a subsection to explain the employed approach in simple terms, dividing it into stages, and referencing Fig. 2 accordingly. Also, reconsider if Fig. 2 is missing any crucial steps for reproduction of the work.
• Fig. 6 is presented before Fig. 5. Additionally, Fig. 6 may be unclear to some readers; please revise it to improve clarity.
• Fig. 8: The part for February 4, 2017, is missing. Please revise.
• L120 and L124: The statements seem contradictory ("acceptable spatial resolution (5 km)" vs. "coarse spatial resolution"). Please clarify.
• L140 and L148: Indicate the release date in L140. Is it the same as in L148?
• Consider moving the Methods section before Data to align data collection with the employed methods. For instance, before describing the data, readers may question why forest density data is needed. Please also include the reason more clearly.
• L162: Include citation(s) for Equation (1).
• L201: Include citation(s) for Equation (2).
• L218-L220: Provide citation(s) for these lines.
• Discuss the snow season (months) in the Materials and Methods section.
• L224 and L226: Define DJF and MAM.
• L239-L241: Rephrase for clarity.
• L287: Avoid using "a determination coefficient close to 1"; rephrase for precision.
• L298: Please include citation(s).
• Add a subsection in Results with a figure discussing temporal changes in snow cover over the entire study period at a monthly time step, as well as the impacts of climate change across the study domains.
• L336: Move this subsection into the Discussion under uncertainties.
• L361: Use subsections within the Discussion to improve readability.
• Appendix A: Provide citations for equations and text.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have clearly responded all the comments and questions .

Reviewer 3 Report

Comments and Suggestions for Authors

Thank you for revising the manuscript. I suggest publishing it.