Dynamic Monitoring of Debris-Covered Glacier Surface Velocity and Ice Thickness of Mt.Tomur, Tian Shan, China

Round 1

Reviewer 1 Report

In this manuscript, the authors used remote sensing technology to analyze debris-covered glacier surface velocity and ice thickness of Mt. Tomur from 2006 to 2020, and validated by in-situ observations. The manuscript reports some interesting findings in a region that is, to date, relatively understudied. I think that the work is generally suitable for the journal Remote Sensing. Some issues still need to be addressed before the manuscript should be accepted.

 

Main Comments

 

1. Please compare the methods of this study for debris-covered glacier with the previously published methods

2. Please check the title. “Tomur peak glaciers” suggest a changed “Mt. Tomur”. The authors need to revise the abstract: the current abstract does not provide an entire summary of the research in this paper; it lacks factual expression. For example “The reliability of the surface velocity and ice thickness obtained from remote sensing was proved using the measured surface velocity and ice thickness of Qingbingtan glacier No.72 stall.” It should state how the results of the validation of the in-situ measured data

3. I would like to see a summary of the latest research in the study area that appears in the introduction.

4. The conclusions are not bad overall but they are based on many numbers, it is more like a description of results in short. I suggest you should add some conclusions which could make your study more interesting for a broader audience. Furthermore, the authors zanalyze the factors influencing the variability of glacier surface velocity in the discussion section, adding content in conjunction with the section in Chapter 5.

5. The whole text of English needs to be greatly improved by a native English glacilogist.

 

Specific Comments

 

Line31: “retreat, shrinking” Expressing the same meaning?

Line32: “glacial” changed to “glacier”

Line40: “materials” do you mean “mass”?

Line54-56: the authors believe that the glacier surface velocity and glacier thickness obtained from remote sensing data cannot be verified for accuracy and reliability, what is the point of this article and suggest that the authors reorganize this sentence

Line80: “a storage capacity” suggest changed “ice volume”

Line81: “above sea level” suggest changed “a.s.l”

Line87: “Glacier Inventory of China (GIC)” Please state whether this is the first or second.

Line96: Fig. 1 needs to be a revision. Figure b should be put on top. a and b have overlays, also Qingbingtan glacier No.72 as a monitoring glacier should be represented in figure b.

Line109-110: “The positions of the ablation stakes were recorded each summer from 2008 to 2022.” The ablation stakes data in the sentence is for 2008-2022, however, the conclusion is for 2008-2009.

Line127: “3.2.1 data” suggest changed “Landsat data”.

Line143: “3.2.2 Glacier surface velocity” suggest a changed “Extraction Glacier surface velocity”.

Line161: “Dxy = Dx² + Dy²”, Check if the formula is correct.

Line174: “3.2.2 Glacier thickness” changed “Glacier thickness estimation”.

Line218: “The estimate of the uncertainty in ice thickness was 850 kg·m^–3” Thickness error is a unit of density?

Line224: “moraine cover glacier” changed to “debris-cover glacier”.

Line234: “elevation” suggest changed “altitude”.

Line236: Did you calculate the equilibrium line altitude (ELA)? Quoted? If cited, add a reference.

Line266: “ice nose” What does this mean?

Line292: “figure6” or “figure7”.

Line297: “assessed” suggest changed “estimated”.

Line393: “accretion zone” do you mean “ablation zone”？

 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript reads well and suggests a new application of GNSS in cryosphere. However, it requires some modifications before getting published:

1.  The quality of images can be improved. For example, the quality of axis in Fig 3, legends in Fig 5, and symbols in Fig 7 are not acceptable.

2. The format of references should be consistent. For example, in section 5.2, the authors have referred to n (Cuffey and Paterson, 2010), which should be in [number] format. 

3. The introduction needs an improvement. Since the authors are talking about a new technique (GPS) for cryospheric studies (glacier movement and thickness), they are highly recommended to include a brief mention to new similar technique in this era to enrich the introduction. My suggestion is adding:
a)  W. Li, E. Cardellach, F. Fabra, S. Ribó, and A. Rius, “Measuring Greenland ice sheet melt using spaceborne GNSS reflectometry from TechDemoSat-1,” Geophys. Res. Lett., vol. 47, no. 2, Jan. 2020, Art. no. e2019GL086477.

b) Ghiasi, Y., Duguay, C. R., Murfitt, J., van der Sanden, J. J., Thompson, A., Drouin, H., & Prévost, C. (2020). Application of GNSS interferometric reflectometry for the estimation of lake ice thickness. Remote Sensing, 12(17), 2721.

c) A. Rius, E. Cardellach, F. Fabra, W. Li, S. Ribó, and M. HernándezPajares, “Feasibility of GNSS-R ice sheet altimetry in Greenland using TDS-1,” Remote Sens., vol. 9, no. 7, p. 742, Jul. 2017,

d) Ghiasi, S. Y. (2020). Application of GNSS Interferometric Reflectometry for Lake Ice Studies (Master's thesis, University of Waterloo).

e) Ai, S., Ding, X., An, J., Lin, G., Wang, Z., & Yan, M. (2019). Discovery of the fastest ice flow along the central flow line of Austre Lovénbreen, a poly-thermal valley glacier in Svalbard. Remote Sensing, 11(12), 1488.

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

Detail comments:

L10: Please add effects of debris cover in your abstract. You have already discussed it in the discussion.

L61-L63: Please add references to this sentence as you referred to studies of surface debris.

L73: Introduce more about RTK-GPS and GPR in the Introduction, such as what they are short for and how they are used.

L93-94: Please provide more specific information of precipitation and temperature to support this sentence or refer to a relative article.

L104-106: Better locate the two GPS receivers in Figure 1.

L113: It should be ‘Glacial surface thickness measurements’.

L132: Landsat 7 ETM+ also has a 15-m panchromatic band. Why did you not use it to generate velocity in the period of 2006-2012? Also, why did you limit using Landsat 7 in the period of 2006-2012? Landsat 7 launched in 1999 with better images in the first few years.

L137-142: Did you use ASTER DEM or ASTER images? What was it or were they used for? In addition, ASTER L1A image was not created from any DEM.

L144-146 & L175-177: It sounds advisable. But why did you list them here?

L184-185: Please give more explanation about why the basal velocity was 25% of the surface velocity.

L222: According to Guillet et al (2022) and Lv et al (2022), at least two of the studied glaciers are surge-type, did your results show any sign of surge events?(Guillet et al., 2022; Mingyang et al., 2021)

L229: No need to list the same uncertainty after every velocity values.

L241: Please use a unified scale bar in (c) and (d) with same color presenting same velocity. Also unify the unit (m a-1) as you used in the text.

L249-250: Please name these glaciers in Figure 1.

L268: Considering many results of velocity and thickness are linked to altitudes, I would suggest add contour lines in Figure 3 and 4.

L283: ‘fount the correlation coefficient was high enough showing .....’

L299: I suggest firstly indicate whether these glaciers are surge-type or not and discuss accordingly, as surge events usually have periodic variations in glacial velocity and surface elevation which may influence your discussion to some extent.

L303: Could you please give the slope condition for glaciers in studied area?

L307-309: Please rewrite this sentence.

L317: The units should be m a-1.

L346: Slope and aspect are two different parameters. You only give aspect analysis in Figure 8. Also, Figure 8 is not directly readable, necessary labels are needed.

 

 

 

Reference:

Guillet, G., King, O., Lv, M., Ghuffar, S., Benn, D., Quincey, D., & Bolch, T. (2022). A regionally resolved inventory of High Mountain Asia surge-type glaciers, derived from a multi-factor remote sensing approach. The Cryosphere, 16(2), 603-623. doi:10.5194/tc-16-603-2022

Mingyang, L., Huadong, G., Shiyong, Y., Guanyu, L., Di, J., Haolei, Z., & Ziyan, Z. (2021). A dataset of surge-type glaciers in the High Mountain Asia based on elevation change and satellite imagery. Retrieved from: http://doi.org/10.11922/sciencedb.00901

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

The authors have responded to most of my previous comments accordingly. The quality of the manu is much more improved I believe. One more thing need to be addressed clearly in the manuscript is that the Landsat 7 data have stripes since 2003 till today. Therefore, the stripes in images could not be the reason of the period selection of 2006-2012.

Author Response

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Author Response File: Author Response.docx