Analysis of Long-Term Dynamic Changes of Subglacial Lakes in the Recovery Ice Stream, Antarctica

Feng, Tiantian; Dong, Hui; Chen, Yangyang; Hao, Tong

doi:10.5194/egusphere-2025-1632

Preprints

https://doi.org/10.5194/egusphere-2025-1632

Preprints

04 Jun 2025

| 04 Jun 2025

Analysis of Long-Term Dynamic Changes of Subglacial Lakes in the Recovery Ice Stream, Antarctica

Tiantian Feng, Hui Dong, Yangyang Chen, and Tong Hao

Abstract. The dynamic activity of subglacial lakes plays a crucial role in modulating glacial dynamic processes and influencing the mass balance of the Antarctic ice sheet. The Recovery Ice Stream (RIS), projected to experience significant mass loss in East Antarctica during coming centuries, requires continued investigation of its subglacial hydrological activity. Prior to 2012, nine active subglacial lakes and their dynamics in the RIS were identified through combined analysis of ICESat satellite altimetry and IceBridge airborne altimetry data. However, recent subglacial hydrological dynamics require further investigation. In this study, we investigate recent activity of nine subglacial lakes in the inventory of the RIS region using newly available ICESat-2 altimetry data, updating their outlines based on observed activity during the ICESat-2 mission period. Furthermore, we identify 14 newly active subglacial lakes designated as RecN1-RecN14. By synthesizing multi-source altimetry data (ICESat, IceBridge, ICESat-2), we establish a 21-year (2003–2023) elevation change time series for subglacial lakes in the RIS region. Through crossover analysis, we precisely identify elevation changes within subglacial lakes and elucidate spatiotemporal patterns across distinct lake sectors, revealing significant disparities between lake centers and their peripheries with a maximum difference of 4 m (e.g., lake Rec6-1). Finally, quantitative analysis of volume changes within primary drainage networks, based on constructed subglacial hydrological networks, confirms effective hydraulic connectivity between subglacial lake clusters in the RIS region. This study elucidates the hydrological dynamics of subglacial lakes in the RIS region, providing scientific basis for a deeper understanding of the evolutionary processes of Antarctic subglacial hydrological systems.

Received: 15 Apr 2025 – Discussion started: 04 Jun 2025

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Journal article(s) based on this preprint

24 Apr 2026

Analysis of long-term dynamic changes of subglacial lakes in the Recovery Ice Stream, Antarctica

Tiantian Feng, Hui Dong, Yangyang Chen, and Tong Hao

The Cryosphere, 20, 2417–2437, https://doi.org/10.5194/tc-20-2417-2026,https://doi.org/10.5194/tc-20-2417-2026, 2026

Short summary

Tiantian Feng, Hui Dong, Yangyang Chen, and Tong Hao

Interactive discussion

Status: closed

RC1:
'Comment on egusphere-2025-1632', Shuai Yan, 10 Jul 2025

This study uses satellite-observed changes in ice surface elevation to infer subglacial hydraulic activity in the RIS region. It addresses a topic of considerable scientific interest and importance and provides a detailed analysis based on a substantial dataset. The methods are thoroughly described, and the results are presented with substantial detail. However, the manuscript lacks a discussion of the broader implications of the findings. Please see my detailed comments below.

Major comments:

1. I appreciate the substantial dataset the authors have analyzed and presented in this manuscript. Given the richness of the data, it is especially important to present the findings in a way that is clear and accessible to readers. I recommend highlighting the key takeaway message at the beginning of each subsection or paragraph in the Results section to help guide the reader through the analysis.

2. Section 4 is titled “Results and Discussions”; however, in my view, it primarily presents the study’s findings with minimal discussion or interpretation of their broader implications. I commend the authors for the significant amount of work invested in this analysis and for the thorough presentation of the results. That said, for a scientific manuscript, it is important to move beyond simply describing findings to interpreting their meaning and situating them within the broader scientific context. For example, what are the implications of discovering a connected subglacial lakes network in a region with significant ice mass loss potential? Could this connectivity influence ice dynamics or impact sea-level rise projections? Additionally, could the methodology presented in this study be applied to other regions of Antarctica? If so, what challenges might arise in extending this approach to different glaciological or observational contexts? These are merely examples intended to encourage the authors to consider the broader scientific context of their work—there is no need to focus on these specific points.

3. The authors estimate lake volume change by multiplying ice surface elevation change by the estimated lake area. While this method can provide a first-order approximation of subglacial water movement and is acceptable for comparing drainage and filling timing, it is known to be an oversimplification (e.g., Stubblefield et al., 2021, https://doi.org/10.1029/2021GL094658). More accurate volume estimates require consideration of additional physical processes and ice–water interactions. The limitations of this approach should be explicitly acknowledged in the Discussion section, along with a justification of why it is appropriate for the specific goals and scope of this study.

Minor comments:

Line #108: “To maximize measurement accuracy” could be more precisely phrased as “To minimize uncertainty” or “To reduce noise in the data,” depending on the intended meaning.

Line #124: “with 500 m resolution” would be clearer as “with 500 m horizontal resolution” to specify the dimension being referred to. The same for line #126.

Line #128: Why not obtain bedrock elevation directly from datasets such as Bedmap3 or BedMachine?

Lines #135 and #151: The basis for selecting the “0.5 m threshold” (line #135) and the “10 km” value (line #151) is unclear.

Line #148: “elevation changes of subglacial lakes” would be more accurately phrased as “elevation changes of the ice surface above subglacial lakes”.

Line #253-254: There appears to be a repeated or redundant statement in this section.

Line #391: more elaboration is needed for “the first-order and second-order stream network”.

Citation: https://doi.org/10.5194/egusphere-2025-1632-RC1
- AC2: 'Reply on RC1', T. Feng, 28 Sep 2025
  
  The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2025/egusphere-2025-1632/egusphere-2025-1632-AC2-supplement.pdf
  
  Citation: https://doi.org/10.5194/egusphere-2025-1632-AC2
RC2:
'Comment on egusphere-2025-1632', Whyjay Zheng, 28 Aug 2025
Thank you for the work on the subglacial lakes in the Recovery Ice Stream (RIS), Antarctica (https://doi.org/10.5194/egusphere-2025-1632). This work updates the existing inventory of subglacial lakes in the RIS by remapping the lake outlines and identifying more active lakes within the RIS, making a valuable contribution to the community. The writing is clear and easy to understand. I only have one major comment and a few minor ones listed below.
Major comment:
The Results and Discussion section is primarily focused on data description, and very little, if any, discussion is present. I would love to read more interpretations from the authors about their data for justification and curiosity. Maybe consider addressing some of the following questions:
What is the core reason that some lake outlines need to be updated? Is it because the existing records are inaccurate, or the lake extent naturally changed (due to different water volume, perhaps) over time? L432 might already provide a short answer from the authors, but I would really love to see a more complete elaboration.

Why did the draining-refilling pattern change significantly after January 2022 (the end of Period III according to Figure 9)? Why did the water stop migrating from the upstream lakes to the downstream lakes?

Is there any drainage-recharge pattern associated with the geographical distribution of the lakes? In other words, do the lakes have similar patterns within a cluster (lower trough, upper trough, and upstream area) and distinct patterns across clusters? If yes, what does it imply?

Minor comments:
The authors use the terms “drainage-filling cycle/pattern” and “storage-drainage cycle/pattern” interchangeably. They may need to be unified for clarity. Additionally, I think it is awkward to say “storage event.” A rechange event may better describe this dynamic behavior.

How did you determine the gap location and width between Rec1-1 and Rec1-2? I ask this because the boundary does not always seem clear to me. For example, data from RGT 0505 (Figure 4c) seems to indicate a wider Rec1-1 section than currently depicted.

Please ensure the submitted work adheres to the TC data policy (https://www.the-cryosphere.net/policies/data_policy.html). The data availability section does not mention the data generated from the work (e.g., new and updated subglacial lake outlines and elevation change maps for each lake). Please deposit “data that correspond to journal articles in reliable (public) data repositories, assigning digital object identifiers, and properly citing data sets as individual contributions.” Additionally, I suggest including visualization(s) (in the main text or as supporting material) that are similar to Figure 3 but encompass all reported lakes. This will enable readers to more easily explore and assess the results.

L44: “DEM differencing” is more common than “differencing DEM.”

L138: What does this slope constraint actually do?

Section 3.2.1: I am not sure whether I understand this correctly, but it appears that the reference DEM is created by interpolating only ICESat-2 data. What is the nominal date of this DEM? If it represents elevations from the ICESat-2 era, why does every time series of elevation changes start from 0 in 2004 (Figures 5-7)?

Equation 1: How did you determine the values of p? I know they are “based on the minimum distance from the elevation measurement points to the lake outline,” but I suppose you did a certain conversion or normalization for p, correct?

Figure 3: Are all panels at the same scale?

Figure 4 b-d: might need a clearer way to tell readers that only the cyan line (elevation change range) follows the axis to the right. I realized this after multiple reads.

Figures 5-7: What are the exact locations of this time series over the subglacial lake area? I ask this because you mentioned that the elevation change is weaker at the edge than at the center of the lake, and in Figure 8 you showed many time series sampled from different locations within one lake.

L267: I do not think we have sufficient evidence to say there is a “continuous rise” due to the huge data gap.

L275: Again, it is a bit confusing to say “seamless connection” here since the IceBridge data have lengthy temporal gaps.

Figure 8: What do the thick dashed lines show?

L382: Elevations cannot “reach their trough.” I suggest finding an alternative to characterize the time series. Maybe something like “ice surface elevations decrease until August 2020…?” Also, “maximum elevation change of -2.8 m” seems awkward since the value is negative.

L395-398: This should be put in the method section. To estimate the volume change, you multiply the lake area by what?

L437-438: “Most newly discovered lakes gradually show active trends during the Operation IceBridge and ICESat-2 periods…” I am not sure if it is legitimate to say this; after all, the altimetry method requires the lake to be active to be detected.

L442: Is it always true over time? (see the second bullet point in the major comment)
Citation: https://doi.org/10.5194/egusphere-2025-1632-RC2
- AC1: 'Reply on RC2', T. Feng, 28 Sep 2025
  
  The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2025/egusphere-2025-1632/egusphere-2025-1632-AC1-supplement.pdf
  
  Citation: https://doi.org/10.5194/egusphere-2025-1632-AC1

Interactive discussion

Status: closed

RC1:
'Comment on egusphere-2025-1632', Shuai Yan, 10 Jul 2025

This study uses satellite-observed changes in ice surface elevation to infer subglacial hydraulic activity in the RIS region. It addresses a topic of considerable scientific interest and importance and provides a detailed analysis based on a substantial dataset. The methods are thoroughly described, and the results are presented with substantial detail. However, the manuscript lacks a discussion of the broader implications of the findings. Please see my detailed comments below.

Major comments:

1. I appreciate the substantial dataset the authors have analyzed and presented in this manuscript. Given the richness of the data, it is especially important to present the findings in a way that is clear and accessible to readers. I recommend highlighting the key takeaway message at the beginning of each subsection or paragraph in the Results section to help guide the reader through the analysis.

2. Section 4 is titled “Results and Discussions”; however, in my view, it primarily presents the study’s findings with minimal discussion or interpretation of their broader implications. I commend the authors for the significant amount of work invested in this analysis and for the thorough presentation of the results. That said, for a scientific manuscript, it is important to move beyond simply describing findings to interpreting their meaning and situating them within the broader scientific context. For example, what are the implications of discovering a connected subglacial lakes network in a region with significant ice mass loss potential? Could this connectivity influence ice dynamics or impact sea-level rise projections? Additionally, could the methodology presented in this study be applied to other regions of Antarctica? If so, what challenges might arise in extending this approach to different glaciological or observational contexts? These are merely examples intended to encourage the authors to consider the broader scientific context of their work—there is no need to focus on these specific points.

3. The authors estimate lake volume change by multiplying ice surface elevation change by the estimated lake area. While this method can provide a first-order approximation of subglacial water movement and is acceptable for comparing drainage and filling timing, it is known to be an oversimplification (e.g., Stubblefield et al., 2021, https://doi.org/10.1029/2021GL094658). More accurate volume estimates require consideration of additional physical processes and ice–water interactions. The limitations of this approach should be explicitly acknowledged in the Discussion section, along with a justification of why it is appropriate for the specific goals and scope of this study.

Minor comments:

Line #108: “To maximize measurement accuracy” could be more precisely phrased as “To minimize uncertainty” or “To reduce noise in the data,” depending on the intended meaning.

Line #124: “with 500 m resolution” would be clearer as “with 500 m horizontal resolution” to specify the dimension being referred to. The same for line #126.

Line #128: Why not obtain bedrock elevation directly from datasets such as Bedmap3 or BedMachine?

Lines #135 and #151: The basis for selecting the “0.5 m threshold” (line #135) and the “10 km” value (line #151) is unclear.

Line #148: “elevation changes of subglacial lakes” would be more accurately phrased as “elevation changes of the ice surface above subglacial lakes”.

Line #253-254: There appears to be a repeated or redundant statement in this section.

Line #391: more elaboration is needed for “the first-order and second-order stream network”.

Citation: https://doi.org/10.5194/egusphere-2025-1632-RC1
- AC2: 'Reply on RC1', T. Feng, 28 Sep 2025
  
  The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2025/egusphere-2025-1632/egusphere-2025-1632-AC2-supplement.pdf
  
  Citation: https://doi.org/10.5194/egusphere-2025-1632-AC2
RC2:
'Comment on egusphere-2025-1632', Whyjay Zheng, 28 Aug 2025
Thank you for the work on the subglacial lakes in the Recovery Ice Stream (RIS), Antarctica (https://doi.org/10.5194/egusphere-2025-1632). This work updates the existing inventory of subglacial lakes in the RIS by remapping the lake outlines and identifying more active lakes within the RIS, making a valuable contribution to the community. The writing is clear and easy to understand. I only have one major comment and a few minor ones listed below.
Major comment:
The Results and Discussion section is primarily focused on data description, and very little, if any, discussion is present. I would love to read more interpretations from the authors about their data for justification and curiosity. Maybe consider addressing some of the following questions:
What is the core reason that some lake outlines need to be updated? Is it because the existing records are inaccurate, or the lake extent naturally changed (due to different water volume, perhaps) over time? L432 might already provide a short answer from the authors, but I would really love to see a more complete elaboration.

Why did the draining-refilling pattern change significantly after January 2022 (the end of Period III according to Figure 9)? Why did the water stop migrating from the upstream lakes to the downstream lakes?

Is there any drainage-recharge pattern associated with the geographical distribution of the lakes? In other words, do the lakes have similar patterns within a cluster (lower trough, upper trough, and upstream area) and distinct patterns across clusters? If yes, what does it imply?

Minor comments:
The authors use the terms “drainage-filling cycle/pattern” and “storage-drainage cycle/pattern” interchangeably. They may need to be unified for clarity. Additionally, I think it is awkward to say “storage event.” A rechange event may better describe this dynamic behavior.

How did you determine the gap location and width between Rec1-1 and Rec1-2? I ask this because the boundary does not always seem clear to me. For example, data from RGT 0505 (Figure 4c) seems to indicate a wider Rec1-1 section than currently depicted.

Please ensure the submitted work adheres to the TC data policy (https://www.the-cryosphere.net/policies/data_policy.html). The data availability section does not mention the data generated from the work (e.g., new and updated subglacial lake outlines and elevation change maps for each lake). Please deposit “data that correspond to journal articles in reliable (public) data repositories, assigning digital object identifiers, and properly citing data sets as individual contributions.” Additionally, I suggest including visualization(s) (in the main text or as supporting material) that are similar to Figure 3 but encompass all reported lakes. This will enable readers to more easily explore and assess the results.

L44: “DEM differencing” is more common than “differencing DEM.”

L138: What does this slope constraint actually do?

Section 3.2.1: I am not sure whether I understand this correctly, but it appears that the reference DEM is created by interpolating only ICESat-2 data. What is the nominal date of this DEM? If it represents elevations from the ICESat-2 era, why does every time series of elevation changes start from 0 in 2004 (Figures 5-7)?

Equation 1: How did you determine the values of p? I know they are “based on the minimum distance from the elevation measurement points to the lake outline,” but I suppose you did a certain conversion or normalization for p, correct?

Figure 3: Are all panels at the same scale?

Figure 4 b-d: might need a clearer way to tell readers that only the cyan line (elevation change range) follows the axis to the right. I realized this after multiple reads.

Figures 5-7: What are the exact locations of this time series over the subglacial lake area? I ask this because you mentioned that the elevation change is weaker at the edge than at the center of the lake, and in Figure 8 you showed many time series sampled from different locations within one lake.

L267: I do not think we have sufficient evidence to say there is a “continuous rise” due to the huge data gap.

L275: Again, it is a bit confusing to say “seamless connection” here since the IceBridge data have lengthy temporal gaps.

Figure 8: What do the thick dashed lines show?

L382: Elevations cannot “reach their trough.” I suggest finding an alternative to characterize the time series. Maybe something like “ice surface elevations decrease until August 2020…?” Also, “maximum elevation change of -2.8 m” seems awkward since the value is negative.

L395-398: This should be put in the method section. To estimate the volume change, you multiply the lake area by what?

L437-438: “Most newly discovered lakes gradually show active trends during the Operation IceBridge and ICESat-2 periods…” I am not sure if it is legitimate to say this; after all, the altimetry method requires the lake to be active to be detected.

L442: Is it always true over time? (see the second bullet point in the major comment)
Citation: https://doi.org/10.5194/egusphere-2025-1632-RC2
- AC1: 'Reply on RC2', T. Feng, 28 Sep 2025
  
  The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2025/egusphere-2025-1632/egusphere-2025-1632-AC1-supplement.pdf
  
  Citation: https://doi.org/10.5194/egusphere-2025-1632-AC1

Peer review completion

AR – Author's response | RR – Referee report | ED – Editor decision | EF – Editorial file upload

ED: Publish subject to revisions (further review by editor and referees) (29 Sep 2025) by Kristin Poinar

AR by T. Feng on behalf of the Authors (30 Sep 2025) Author's response Author's tracked changes Manuscript

ED: Reconsider after major revisions (further review by editor and referees) (24 Oct 2025) by Kristin Poinar

Dear Tiantian Feng, Tong Hao, and co-authors,

Thank you for your revised manuscript. I have read it in detail alongside the reviews and your earlier responses to the reviews. Although the manuscript has improved slightly from its first version, there is still much more progress needed before it could be considered for final publication. I would need to see more substantial changes made to the manuscript before I would be able to send it back to the reviewers to evaluate again. Below, I detail the improvements that would need to be made. All line numbers refer to the differenced ("Authors' Tracked Changes" or ATC) document.

Major areas where improvement is needed:

1. Formal separation of Methods, Results, and Discussion into sections.
The manuscript as written does not adequately separate its ideas into the appropriate scientific categories of Methods, Results, and Discussion. A substantial amount of text in the Results section actually describes methods and should be moved to there; similarly, there needs to be a Discussion section of its own that contains contextualizing, hypothesizing, and/or speculation about the meaning of the results within what is already known about Antarctic subglacial lakes (in the literature).

L237-242: This text should be moved to the Methods section

L263-274: This text should be moved to the Discussion section

L285-291: This text should be moved to the Methods section

L491-495: This text should be moved to the Methods section (where the simplified volume change calculation is described) or the Discussion (where the implications of this simplicity should be discussed). In the Discussion, the bias should be addressed - do you think the method overestimates or underestimates the volume of the lake, and does the magnitude of the bias depend on the size of the lake? If so, how does that affect the volume change calculations presented? See Point #4 below.

2. Better sophistication of the discussion.

The authors have added text in response to both reviewers' assessments that a discussion / interpretation of the results was missing. However, the text added is inadequate. For instance, one major point that is made at least twice in this revision is that "under the influence of basal topographic features, [the lakes] form a complex hydrological connectivity network" (L390-391). This is already pretty well assumed and understood by the community, and as posed here is too vague to be of any contribution. The authors need to do some thinking about what their research has revealed that was not previously known, and go forward from there to present these results toward possible implications. For instance, what is the significance that Lake Rec1 is actually two lakes that fill and drain on independent schedules? Is there any significance that both these lakes are located exactly upstream/downstream of one another on the same higher-order stream shown on Figure 9? These are just some examples; I do not mean to suggest that these are the only two questions that need to be probed, but rather I pose them as ways you might put your specific results into a broader context about our understanding of subglacial water flow. This is crucial if the manuscript is to be accepted for publication.

I found the response to Reviewer 2's first suggestion ("Why did the draining-refilling pattern change significantly after January 2022 (the end of Period III according to Figure 9c)? Why did the water stop migrating from the upstream lakes to the downstream lakes?") to be unconvincing. If, as the authors say, "active subglacial lakes reach drainage thresholds at lower volumes over time, possibly stemming from channel erosion and expansion," then what allowed the onset of Period III (May 2021 in Figure 9c)? At this time, the lakes appear to enter a period of larger (not smaller) capacity, implying higher thresholds for drainage.

I did not find a response to another of Reviewer 2's suggestions for discussion, "What is the core reason that some lake outlines need to be updated? Is it because the existing records are inaccurate, or the lake extent naturally changed (due to different water volume, perhaps) over time?" This is a natural and important question to address in the Discussion.

L522-523: "the drainage regime in the RIS is characterized by long-term, sustained water transport rather than episodic outburst floods." Is this consistent with previous findings of the Recovery Lakes, and/or with previous findings of other lakes (e.g. in the Siple Coast Ice Streams)? This is another opportunity to put your results in the context of the literature.

3. Addition of implications to the Abstract and Conclusions.
As mentioned above, both reviewers requested additional text of a "discussion" or "broader implications" nature. When these ideas are better developed, they need to be added to the Abstract and the Conclusions, as well as to the main text.

4. Uncertainty analysis.
A central component of this research is the volume change over time of each individual lake and of the RIS system as a whole. Figure 9 shows that the periodic recharge and discharge of each lake are similarly sized; such "differences of large number"-type problems in science require uncertainty analysis. Specifically, the uncertainties on the discharge / recharge volume rates are needed, as this would let us know if the net volume change is significantly different from zero, within measurement errors. For instance, on L467 and L481, volume change numbers are presented, but without uncertainty. Similarly, on L474, the finding is reported to be "significantly higher than discharge of the previous period"; however, without quantified uncertainties, it is impossible to say whether the change is significant or not. The reviewers, and now the modified text, suggest that the coarse "constant area" approximation for water volume used here is not accurate compared to the viscous changes described by Stubblefield et al. (2021). What remains is to quantify the magnitude and (if possible) the sign of the bias, and incorporate this uncertainty into the volume change numbers reported.

5. Explanation of the gap between lakes.
L248-251: This sentence was added to address a question by Reviewer 2 on why the gap between the lakes, as defined by the authors, seems to vary (e.g. Figure 4). This sentence does not address that concern. As pointed out by Reviewer 2, one can see in Figure 4 that the gap between gray zones (Rect1-1 and Rect-2) varies across the three panels. I suspect that this stems from the slightly different placements of the three ICESat-2 tracks analyzed in the figure - with close study of Fig. 4a, one can see that the red track (Fig. 4b) crosses the lakes at their closest approach, while the blue track (Fig. 4d) is at a point of wider separation. This should be explained, probably in the caption of Figure 4.

Minor changes that would improve the manuscript:

L141-142: This summary of why steep areas are "prone to measurement errors" in ICESat and ICESat-2 is too simplistic and too critical of the ICESat-2 products. The original sentence mentioned the root cause, footprint positioning accuracy; this is important to keep.

Use of "left" and "right" to refer to directions within the lakes: This should be corrected to compass directions, like "north" and "south" or "northeast" and "southwest", depending on the lake.

The downstream lakes are important but make up a very small part of Figure 1. On line 280, they are referred to and it would be natural to cite a figure here (Fig. 1) although in its current form, Figure 1 does not show these lakes very well. I suggest adding a panel to Figure 1 that shows these better, perhaps without the IceBridge lines, similar to what you have done for the middle group of lakes.

Figure 5: It is difficult to distinguish the data (dots) from the visual guides (lines). I recommend making the dots larger, making the dashed lines finer, or possibly both.

Figure 5: It is not evident what components of the ICESat-2 time series are "data" versus "visual guides", as this panel has only lines (no dots). I understand that ICESat-2 samples much more densely in time than the other eras, but this needs to be explained in the caption or perhaps by pointing to Figure 8, which does represent individual observations as dots.

L366 - The decline is referred to as "continuous", but this is not accurate as there are brief periods of rise interspersed. This should be corrected to "nearly continuous". Same on L267, L318, and perhaps other places where this or similar wording is used.

Figure 9: The caption incorrectly says the histograms show elevation difference, while the axis labels say instead volume difference (km3).

If these shortcomings are rectified, I will be able to reconsider the manuscript for review and publication.

Cheers,
Kristin Poinar

Hide

AR by T. Feng on behalf of the Authors (20 Dec 2025) Author's response Author's tracked changes Manuscript

ED: Publish subject to revisions (further review by editor and referees) (18 Jan 2026) by Kristin Poinar

Dear Tiantian Feng, Tong Hao, and co-authors,

Thank you for your revised manuscript. I have reviewed it and find that you have improved the paper. However, the paper requires further revisions before it can be sent back to review. I detail these requirements as follows.

- The abstract is too long (350 words). It needs to be shortened to 150-250 words, per the journal guidelines at https://www.the-cryosphere.net/about/manuscript_types.html

- I appreciate that you have added the values of the measurement uncertainties of the lake volumes. However, the uncertainties are too precise, reported to 0.001 km3 compared to lake volumes reported to 0.01 km3. Please revisit the calculation and report both the measurement and uncertainty to the level of significance the results hold (I suspect 0.1 to 0.01 km3).

- In the long paragraph added to Section 4.4, there is much causal speculation interspersed with the reporting of results. This should not be in Results, but Discussion.

- Section 5.1: This section is much longer than it needs to be. The first paragraph states that filling–draining cycles affect the outlines over time, in agreement with previous findings, with some lakes dynamic and others dormant over the observation period. The current manuscript takes 9 sentences to report this - which is much too long. This is true of the other four paragraphs in Section 5.1 as well.

- L 505: "Subglacial lake outlines naturally evolve over time in response to filling-draining cycles" - This statement needs citation.

- Section 5.2: Most of the first half of Section 5.2 should be moved to the Methods. In the second half, the idea that the reported volume changes systematically underestimate the true changes should be made much more clear here - I suggest use of the words "bias" or "underestimate". Finally, I can't see how the assertion that the satellite data captures the signal accurately is supported here. If errors vary from 0.53 times the "true" signal to 0.93 times, this is quite substantial and would be hard to call "accurate". Unfortunately, these large errors cast doubt on the next two sentences, which assert that there is large natural variability. I am afraid that this argument is very difficult to buy. The authors should rethink this section and rewrite it so that it more honestly presents the reliability of the findings.

- L 564: "... indicating a relatively short filling-draining cycle for lakes in the primary drainage networks." This is ungrounded - short compared to what expectation? This needs citation. Alternately, you could state the approximate interval (2-5 years) and remove the commentary that this is long or short.

- Finally, I encourage you to deposit your code into a open-access repository to increase the probability that others can build on your work. A pointer to this repository should then replace the sentence "Other code used in this study is available from the corresponding author upon reasonable request."

I hope you will take the effort to address these changes. When I receive the newly revised manuscript, I will be able to send it out for review again.

Cheers,
Kristin Poinar

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AR by T. Feng on behalf of the Authors (07 Feb 2026) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (24 Feb 2026) by Kristin Poinar

RR by Shuai Yan (14 Mar 2026)

RR by Whyjay Zheng (16 Mar 2026)

ED: Publish subject to technical corrections (08 Apr 2026) by Kristin Poinar

Dear Tiantian Feng and co-authors,

The reviewers have now re-evaluated your manuscript. I am pleased to accept your manuscript conditional on fixing four minor issues discovered by the reviewers. I have pasted them below for your convenience. I do not think these edits will be difficult for the authors, nor do they change the science discovered and reported in any way.

Early congratulations on the acceptance of your manuscript. Once you have implemented the technical corrections, your manuscript will proceed to the typesetting team. Please work these diligent folks to finish the publication process.

Cheers,
Kristin Poinar

Comment 1: I noticed that the manuscript alternates between phrases such as “draining-filling” and “filling-draining,” as well as “hydrologic” and “hydrological.” If these terms are intended to convey different meanings, please clarify. Otherwise, I suggest using the terminology consistently throughout the manuscript.

Comment 2: Please carry out one more careful language edit to correct small grammatical and formatting issues. Below are a few examples I noticed:
Title: Ensure capitalization is consistent and aligned with the journal guidelines.
Line 93: “are” should be “is.”
Line 98: “require” should be “requires.”
Line 246: “four remains active” should be “four remain active.”
Line 254: “contrast” should be “contrasting.”
Line 262: Remove the comma before “contains transitional elevation signals that create uncertainty.”
Line 273: “See” should be “see.”
Line 669: “run of the code” should be “run the code.”

Comment 3: In the code and data availability statement, the final Zenodo link should be updated to: https://doi.org/10.5281/zenodo.18354195

Comment 4: For Figure 11, the authors state, "The shaded areas indicate the uncertainty range for each lake," but I do not see any shaded areas in the figure.

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AR by T. Feng on behalf of the Authors (13 Apr 2026) Manuscript

Journal article(s) based on this preprint

24 Apr 2026

Analysis of long-term dynamic changes of subglacial lakes in the Recovery Ice Stream, Antarctica

Tiantian Feng, Hui Dong, Yangyang Chen, and Tong Hao

The Cryosphere, 20, 2417–2437, https://doi.org/10.5194/tc-20-2417-2026,https://doi.org/10.5194/tc-20-2417-2026, 2026

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Tiantian Feng, Hui Dong, Yangyang Chen, and Tong Hao

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Month	HTML	PDF	XML	Total
Jun 2025	278	70	20	368
Jul 2025	114	26	4	144
Aug 2025	328	42	6	376
Sep 2025	1,004	50	10	1,064
Oct 2025	82	30	4	116
Nov 2025	40	76	8	124
Dec 2025	94	62	2	158
Jan 2026	120	136	6	262
Feb 2026	66	38	4	108
Mar 2026	134	210	4	348
Apr 2026	56	83	0	139
May 2026	3	6	0	9

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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

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This study focuses on the long-term subglacial hydrological activity of the Recovery Ice Stream in East Antarctica. We update the outlines of reported lakes based on their recent activity and identify 14 new lakes. A 21-year record of elevation changes of these lakes is constructed using multi-mission altimetry data. We also reveal spatial variability in elevation change patterns within several typical individual lakes. Our hydrological network confirms hydraulic connectivity among these lakes.

Analysis of Long-Term Dynamic Changes of Subglacial Lakes in the Recovery Ice Stream, Antarctica

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