Snowcover Survey over an Arctic Glacier Forefield: Contribution of Photogrammetry to Identify “Icing” Variability and Processes

Round 1

Reviewer 1 Report

This research by Eric Bernard, Jean-Michel Friedt and Madeleine Griselin studied the snow accumulation and icing dynamic patterns with two years of field efforts using sUAV, DoD, and snow probing depth measurements in a small glacier foreland in High Arctic. The methodologies applied are challenging in answering the proposed research questions, but the authors managed to conduct a well-designed work and provided detailed interpretations and explanations in results and discussion. A few major concerns are listed below; while more detailed comments and edits are in the attached PDF file. My recommendation is “accept after minor revision”. Upon receiving satisfactory revisions, the manuscript can be considered for publication in my opinion.

 

Major comments:

• As mentioned in Introduction, this method is good for adapting the fast-changing weather in the field to ensure the SfM assumption - constant illumination and static terrain features. If so, how is it justified to study such short-lived phenomenon? Why we care about characterizing a feature that only lasts short period of time and may change next day or so? The snow depth might change quickly and largely depend on the wind, the time of the day, the time of the year, and the micro-topography etc.

 

• Figure 3 right panel: should it be the 2m ArcticDEM? I’d suggest to show the hillshaded version of it because it better demonstrates the terrain.

 

• I don’t see how the 2m ArcticDEM was used in your analysis. Could you help explain more on this?

 

• Location of GCPs are necessary. If it can be added on one of the maps, it would be great.

 

• In reporting the numerical results, there are no uncertainty or error estimation. It needs to be taken into consideration with regards to accuracy and precision issues of the study.

 

• How would one discern icing areas on two images of Figure 5? I hardly can tell where are the icings. Would it be possible to map them out so readers can know what and where to look at?

 

Last but not the least, there are some typos and a few grammatic issues in the text. Please check carefully. (I highlighted some without comments in the PDF.)

Comments for author File: Comments.pdf

Author Response

please find attached to this message the rebuttal letter addressing all comments from reviewers.

Author Response File: Author Response.pdf

Reviewer 2 Report

This paper is competently written with a state of the art well presented.

However due to the high quality of the papers published in the Remote Sensing journal I kindly ask the authors to make the following improvements:

- It is not clearly presented in the introduction and conclusions parts what is original in this paper. A lot of studies already presented results and techniques about snow accumulation and icing thickness. I kindly ask the authors to motivate and better present the elements of originality.

- line 304: what means “snowcover is quite deep”….? Please add an approximate value here!

- please add a scale on the Figure 9. What is the scale for figure 2 c and 2 d?

- please define the DEM acronym (Digital Elevation Model)

Author Response

please find attached to this message the rebuttal letter addressing all comments from reviewers.

Author Response File: Author Response.pdf

Reviewer 3 Report

The overall aim of the study is to demonstrate the potential of UAV-SfM to evaluate snow cover processes. Digital models were created at maximum/minimum snow accumulation, and then analyzed to investigate icings dynamics

Broad comments: 

• Spelling and grammar should be revised
• Consistency in some Figures need to be Improved
• Clarifications are required for Some statements  to make them more critical

Specific comments:

• Line 6: what does “/” mean? I suggest being more specific in this statement. The SfM method was applied to process the UAV images..
• Line 11: What is the abbreviation of DEM? In general, Digital Elevation Models (DEMs) can be segmented into Digital Terrain Models (DTMs) and Digital Surface Models (DSMs), Please clarify which model has been used in the study, DTMs or DSMs? I suggest refining the term for consistency.
• Lines 14-18: It would be good to revise and split it into two sentences. I’d also suggest changing “correlation between avalanche probe…” to (the) correlation
• Lines 19-20: please revise the sentence; for example, change the word ‘discrepency’ to discrepancy. Also, change “…and difference of DEMs” to the differences of DEMs”
• Line 21: please change SfM-UAV to UAV–SfM
• Line 24: typo, please change ‘Crysophere’ to Cryosphere
• Line 29: typo change ‘adpatation’ to adaptation
• Lines 29-30, please amend the sentence, there are some grammatical/ spelling mistakes; for example, change “the proglacial moraine significantly increasess in the same time” to the (proglacial moraine significantly increases at the same time).
• Line 36: change “results in” to result in
• Lines 42-43: where do these phenomena occur? Who did observe them?. Please clarify and check the spelling, e.g., change “occurence" to occurrence.
• Lines 49-54: Please check the spelling, e.g., “geomorphologiocal” to geomorphological; “accuratly” to accurately; “Sfm” to SfM, etc.
• Line 45: What are fast and short processes?
• Lines 55-56: the statement is not clear. What are the “flexible means”?
• Line 59: The author states that “The weather changes so fast”, how often does the weather change?. Use (field campaigns have to..) instead of “has to”
• Lines 64-66: Not clear, I suggest rewriting the statement
• Lines 66-71: Please check the spelling, e.g., use literature instead of “litterature”; quantifying instead of “quantifing”; seasonal instead of “seasonnal", disappearance instead of “desapearance” etc.
• Line 104: The author states that “2 m resolution DEM is accurate enough for UAV data referencing and validation”, why 2 m is accurate? Please clarify and add references to support the sentence.
• Line 114: Change QGis to Quantum Geographic Information System (QGIS); the version of QGIS? You could also add the URL of the software.
• The legend/ scale bar in figure 3 is not clear, I suggest making them bigger  
• Section 3.2. More information about the aerial images is required; for example how many aerial images? overlap and sidelap? Camera type? Please provide more detail to make reader understand,
• Line 204: I suggest explaining how you increased the sharpness of the images
• Section 3.4. The author states that DEM was created in Photoscan and then analysed in QGIS, but did not specify which digital model was used, DSM or DTM?
• Lines 210-225: I suggest adding references to support the methodology
• What is the DOD stand for?
• Lines 349-354: what are the previous studies? please add them to support your statement. 
• Lines 355-358: I suggest amending the sentence
• Line 359: What is RADAR stand for?

Author Response

please find attached to this message the rebuttal letter addressing all comments from reviewers.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The revised manuscript is improved, and all comments and suggestions have been taken into consideration.