the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 04 Jun 2026
An experiment to resolve system-scale lake ice properties shaped by environmental processes
Abstract. The multi-scale composition, structure, and dynamics of seasonal ice floating on freshwater lakes are influenced by ambient conditions. Here we describe a comprehensive geoscience experiment for lake system imaging and monitoring of spatiotemporal ice property variations. We explore the resolution of meteorological and environmental driving mechanisms that can include the quantification of methane degassing from boreal lakes. The project centerpiece is a seismic array of 210 geophones arranged in an aperiodic tiling configuration that was deployed in February 2025 on the ~25 cm thick ice of Lake Pääjärvi in southern Finland. The 10-km scale lake array is complemented by three dense circular arrays, 31 land-based sensors, eight broadband seismometers, three accelerometers, a rotational seismometer, a Distributed Acoustic Sensing system with a 1 km-long fibre optic cable, an underwater echosounder, a microphone, a Ground Penetrating Radar (GPR) survey, water chemistry measurements, manual ice thickness sampling and ice coring, and meteorological observations. We observe the strongly dispersive QS flexural mode and the weakly or non-dispersive QS₀ and HS₀ modes excited by hammer shots, icequakes, and environmental sources and reconstruct the average propagation using beamforming and noise correlations. Propagation speed estimates for the three modes range approximately between 20–100 m s⁻¹, 3000–3400 m s⁻¹, and 1650–1800 m s⁻¹, respectively. High values for the Poisson's ratio ν = 0.42 and Young's modulus E = 8.59 GPa reflect the overall competent characteristics of the ice referred to as teräsjää (steel ice). Seismic activity in the 0.03–0.2 Hz band increases during high wind speed episodes, and signals above 0.1 Hz correlate with rapid air-temperature cooling events. The GPR profile images the spatial ice variability across the lake that is compatible with the in-situ measurements, and we show that seismo-acoustic observations can be inverted for similarly compatible thickness estimates. The geochemical water and ice sample analysis suggests Lake Pääjärvi is a source of methane, and localized ebullition can potentially be resolved from echosounder data. This synthesis demonstrates that the application of environmental seismology concepts can form a bridge between bottom-up ebullition monitoring and remote-sensing approaches.
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Status: final response (author comments only)
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RC1: 'Comment on egusphere-2026-2106', Anonymous Referee #1, 23 Jul 2026
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AC1: 'Reply on RC1', Felix Strobel, 10 Sep 2026
We thank you for the constructive review, which helps us to improve the manuscript.
Summary:
This work presents a detailed overview of an impressive lake ice experiment in Finland. It probably represents the densest lake ice geophysical campaign ever deployed, with DAS, many nodes and 3 arrays of seismometers, as well as other subsurface instrumentation. The experiment and indeed the manuscript are impressive, with the manuscript providing a comprehensive overview of the dataset and initial analysis. Obviously the authors intend to work on a number of different studies beyond this work, which is of course completely fine, with this work clearly intended to act as a reference point for the dataset and preliminary analysis.
The work is perhaps a little ambitious when it comes to the methane/ebullition processes and trying to observe any geophysical signature in the lake ice from trapped gases, but otherwise represents a grounded study where the analysis is supported by the observations.
Reply: We agree and consider to carefully reword and where necessary restructure parts of the discussion to properly balance the premises and assumptions that led to the work completed during the experiment or deployment, including geochemical sampling, and what has actually been observed related to methane ebullition and gaseous phases in the ice. This update should then leave no confusion or ambiguity about acquisition choices and possibly limited methane observations.
My comments are minor and address minor points that do not alter the overall premise of the work. I therefore suggest that after minor revisions, this work should be suitable for publication.
General comments:
The abstract starts by stating that the experiment/study is focussed on ice properties, but then the end of the abstract introduces methane and ebullition processes. I feel the abstract would benefit from a coherent start and end, clearly communicating whether the core goals are to investigate ice properties or ice and lake processes.
Reply: We agree that a revision can make the abstract sharper with respect to planning or ideas, and actual observations, as outlined above. However, we disagree by being asked to make a clear distinction regarding the investigation of ice properties OR dynamic processes. Clearly, properties reflect and constrain processes, and processes govern properties. We wish to be clearer about this in a revised manuscript.
The conclusions are interesting, but the links to the geochemistry analysis are barely/not mentioned at all. The methane / greenhouse-gas framing is not supported by the results presented. The abstract and introduction suggest that the authors might try to quantify methane degassing and/or infer methane concentrations from seismic data. Yet the authors' own geochemistry shows CH4 in the ice is only ~0.01–0.1 µmol/L — a minor constituent of the trapped gas. As written, the methane imaging goal is aspirational and is partly undercut by the paper's own data. I recommend either reframing any geochemical analysis and inferences as the potential topic of future work or presenting quantitative evidence that seismic observables here are sensitive to the gas volumes actually present.
Reply: We can certainly update the conclusion section with key observations regarding the geochemistry analysis; we agree, it does lack a reference to the discussion in the other parts of the manuscript.
Regarding the methane ‘framing’, we agree with the observation that the related field work part, analysis, and results are not properly balanced, as outlined above. We consider careful rewording of the associated text elements to make the discussion more coherent. We think that the system-scale propagation reconstructed from correlations supports the idea of using seismic imaging methods such as passive tomography as a tool to infer spatially variable fluxes of greenhouse gas from the lake to the atmosphere. We consider that our geochemical analysis results can inform modeling of ice formation and its effective elastic properties. Together with the observed travel time uncertainties, our dataset can thus be used to estimate the limits of resolving spatial variations of gaseous phase concentrations in ice from seismic data.
Tomography is suggested but not performed. The title and several parts of the text imply spatially resolved imaging, but the paper reports only laterally averaged velocities/moduli plus a qualitative statement that tomography could be performed.
Reply: Here, too, we plan to remove any ambiguous references to a tomography performed in this work. We carefully revise wording about what is presented or done in this work and what our results imply for later or future work.
The wording “we expect…” is used, but it is a shame that basic analysis is not followed through.
Reply: We carefully revise wording of such ambiguous phrases that can lead to misunderstandings about what is performed here and what can be done later. We disagree with the reviewer’s statement that we do not follow through with basic analysis, as is reflected by the overall length of section 3.2.4 in question.
The cross-correlations alone do not show a lot. This is legitimate for a data/experiment paper, but the title and abstract should be adjusted so readers are not led to expect tomography.
Reply: We disagree; the cross-correlation gathers are rather beautiful, and the RR and TT gathers clearly demonstrate system-scale propagation.
We can understand where the criticism of the title comes from, and the repeated reference to tomography, which is not presented here. From the title, the reviewer expects an actual resolution of lake scale ice properties, i.e., a tomographic image. We outlined the need to carefully rephrase statements that can be ambiguous about ambition and actual analysis and results, and from that the title should then not imply a tomography imaging result. However, to be very clear, we can consider changing the title from
“An experiment to resolve system-scale lake ice properties shaped by environmental processes”
to
“An experiment to analyze system-scale lake ice properties shaped by environmental processes”The data availability embargo kind of goes against the premise of the paper acting as a description of a dataset. The data-availability statement places the dataset under embargo until May 2028. Ideally, the dataset embargo would end upon publication of a broad dataset description paper like this. For a paper whose central contribution is the dataset, referees and readers cannot currently access, inspect, or reuse it, which limits reproducibility and the paper's value and impact. I can very much understand the rational behind such a decision regarding the dataset, but I do worry that it stifles the impact of this paper. Ideally, this paper would not have been submitted until when the dataset were available. At the very least, some processed data should be made available to make some of the results reproducible. I don’t think it is fair to ask for sufficient raw data to make noise cross correlations, as that could be the entire dataset, but perhaps enough data to get a flavour of noise conditions would be useful.
Reply: In response to the reviewing process, we shift our focus away from a ‘data paper’ towards an ‘experiment paper’, as the title already suggests. We disagree that a data paper cannot or should not be published before the data is openly available; in our perception, this is done all the time. We practiced this before, e.g., for the papers 10.1785/0220190253 and 10.1785/0220210195. We are prepared to tolerate potential negative effects on the paper’s impact as suggested by the reviewer. If the data availability statement policy of this journal allows, we consider adding a statement like “Prior to the embargo end, data can be shared under a collaboration agreement by contacting the authors.”
Specific comments:
Section 2.2 Consider condensing. It is out of balance with other sections of the paper.
Reply: We are not convinced but consider shortening it.
Section 3.2.4. A acoustic signal attributed partly to snowmobiles appears in the correlations. Briefly discuss whether anthropogenic sources bias the ambient-noise correlation results during the campaign.
Reply: We can add a statement like “We do not expect that the intermittent human activity on the ice degrades the quality of the obtained average correlation gathers or influences our estimates of the propagation velocities. A conclusive assessment of the influence of anthropogenic sources requires a more comprehensive and detailed analysis of the wave field anatomy.”
Section 3.4 (GPR). Is the higher estimated EM velocity due to the average ice thickness used? It is important to pin down this point if you are going to make inferences about trapped gas affecting velocities.
Reply: We acknowledge the confusion here. We prefer to remove the related statement because a detailed discussion to resolve this appears out of scope, and the obtained value is not critical for our understanding or the discussion.
L566 – aquatic normally suggests life/biological study of water environments. Hydrological would probably be a more appropriate word to use here.
Reply: We prefer to keep “aquatic” where we write about CH4/geo/bio-chemistry, and change to hydrological-/lake-/… when writing about physical properties or processes.Technical/typos:
L257: "We transfered" → "We transferred."
Need to define QS where first used (ideally define in the abstract as first used there.)
Reply: We can define QS, QS0, and SH0 in the abstract.
Generally define all acronyms at first use (e.g. ADR, PPSD, PSD, FK, RTK DGPS).
Reply: We pay attention to this policy.
Citation: https://doi.org/10.5194/egusphere-2026-2106-AC1
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AC1: 'Reply on RC1', Felix Strobel, 10 Sep 2026
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RC2: 'Comment on egusphere-2026-2106', Anonymous Referee #2, 27 Jul 2026
The paper provides an interesting application of geophysical instruments for studying lake ice properties. From a methodology point of view, the work is very thorough. It is clear that careful consideration was taken in the establishment of the field campaign which provides support for the dataset produced as a result of it. The goal of the paper appears to be detailing the methodology and variables collected. However, the main weakness of the paper is that there is discussion beyond this goal which causes some confusion to the reader.
The introduction dedicates considerable space to a background discussion on methane ebullition from high latitude lakes. Additionally, the introduction states, “We explore here the possibility to resolve spatially variable encapsulated gas using seismic tomography”. However, the actual paper does not detail these results or provide any discussion on this areas of work. Similarly, in the abstract (L4-5), these claims are also made but again not followed up in the remainder of the article. This makes the article come off as misleading in a way.
The authors clearly intend to pursue this line of investigation, and it is certainly an interesting one, however, it is not fully detailed and explored in this paper. Therefore, text referring to it should be removed/heavily modified. I think the discussion does a good job of outlining the future planned studies and would be a good place for this text to reside.
Another minor issue is that there are claims/statements made that lend themselves more to a research paper as opposed to a data paper. For example, Line 335 to 344, there is discussion of correlation between wind and broadband activity, however, mechanisms for this correlation are not discussed. While I do not expect the authors to have an answer to these immediately as analysis of the data is ongoing, it does not seem well suited for a data paper. Other statements such as “We expect” fall into a similar category. Again I assume analysis on these areas is ongoing, however, the preference would be that the data paper focuses on what data was collected, the quality of that data, any additional processing, and how that data may be used for further study.
While these points may seem critical, on a whole the paper is good. It is well written and with minor re-works to the text can be made ready for publication.
The two major suggestions needed:
- Reduce the focus on methane ebullition work to emphasize it as a future area of study and not a goal for this manuscript.
- Modify the wording within the paper so that there is more a focus on what was observed in the data and not what is expected or has not been fully analyzed unless it is clearly being noted as a future study.
Citation: https://doi.org/10.5194/egusphere-2026-2106-RC2 -
AC2: 'Reply on RC2', Felix Strobel, 10 Sep 2026
We thank you for the constructive review, which helps us to improve the manuscript.
The paper provides an interesting application of geophysical instruments for studying lake ice properties. From a methodology point of view, the work is very thorough. It is clear that careful consideration was taken in the establishment of the field campaign which provides support for the dataset produced as a result of it. The goal of the paper appears to be detailing the methodology and variables collected. However, the main weakness of the paper is that there is discussion beyond this goal which causes some confusion to the reader.
The introduction dedicates considerable space to a background discussion on methane ebullition from high latitude lakes. Additionally, the introduction states, “We explore here the possibility to resolve spatially variable encapsulated gas using seismic tomography”. However, the actual paper does not detail these results or provide any discussion on this areas of work. Similarly, in the abstract (L4-5), these claims are also made but again not followed up in the remainder of the article. This makes the article come of as misleading in a way.
The authors clearly intend to pursue this line of investigation, and it is certainly an interesting one, however, it is not fully detailed and explored in this paper. Therefore, text referring to it should be removed/heavily modified. I think the discussion does a good job of outlining the future planned studies and would be a good place for this text to reside.
Reply: As in our response with reviewer #1, we agree and consider to carefully reword and where necessary restructure parts of the discussion to properly balance the premises and assumptions that led to the work completed during the deployment, including geochemical sampling, and what has actually been observed related to methane ebullition and gaseous phases in the ice. This update should then leave no confusion or ambiguity about acquisition choices and eventually limited observations. We plan to remove any ambiguous references to a tomography performed in this work. We carefully revise wording about what is presented or done in this work and what our results imply for later or future work.
Another minor issue is that there are claims/statements made that lend themselves more to a research paper as opposed to a data paper. For example, Line 335 to 344, there is discussion of correlation between wind and broadband activity, however, mechanisms for this correlation are not discussed. While I do not expect the authors to have an answer to these immediately as analysis of the data is ongoing, it does not seem well suited for a data paper. Other statements such as “We expect” fall into a similar category. Again I assume analysis on these areas is ongoing, however, the preference would be that the data paper focuses on what data was collected, the quality of that data, any additional processing, and how that data may be used for further study.
Reply: We plan to reword statements like “we expect” to be less ambiguous about what is done here and planned later. About mechanisms regarding the links between temperature and wind speed and seismic energy we plan on updates in this direction:
Figure 10b quantifies the frequency dependent correlation of high seismic energy with low temperatures. The time series and spectrogram both show a much reduced seismic activity after 21 February 2025. In this second part of the experiment, temperatures were mild in comparison and fluctuated around the freezing point. The spectrogram further exhibits daily variations in seismic energy release, where more active periods are observed during day times. These patterns suggest that changing air temperatures play an important role for the seismic behavior of the lake ice layer, e.g., ice cracking is a response to thermal variations.
At frequencies below 0.2 Hz the activity differs from the high frequency response (Fig. 10c). Periods of elevated amplitudes in the 0.03−0.2 Hz range last from hours to days. We find that these episodes correlate well—indicated by a correlation coefficient up to 0.8 (Fig. 10d)—with faster wind speeds (Figs. 10c, 2c) and wind gust speeds (Figs. 10c, A1a). A plausible mechanism for this observed synchronicity is the excitation of low-frequency flexural-gravity waves, considering that this excitation requires wind speeds above the minimum phase speed of the flexural waves.
While these points may seem critical, on a whole the paper is good. It is well written and with minor re-works to the text can be made ready for publication.
The two major suggestions needed:
- Reduce the focus on methane ebullition work to emphasize it as a future area of study and not a goal for this manuscript.
Reply: Our revision can reduce focus on methane ebullition but needs to keep sufficient background material for motivating the geochemistry sampling work during the experiment and the ebullition sounding.
- Modify the wording within the paper so that there is more a focus on what was observed in the data and not what is expected or has not been fully analyzed unless it is clearly being noted as a future study.
Reply: Our planned revision should leave no confusion or ambiguity about acquisition or data collection choices, observations, and topics for future studies.
Citation: https://doi.org/10.5194/egusphere-2026-2106-AC2
Data sets
The DYNALake project dataset Felix Strobel, Gregor Hillers, Tom Jilbert, John Loehr, Christian Stranne, Tahvo Oksanen, Jonathan Vänskä, Roméo Courbis, Annukka Rintamäki, Amir Sadeghi-Bagherabadi, Lasse Weißgräber, Yinshuai Ding, Marc de Langenhagen, Eduardo Valero Cano, Kwabena Atobra, Vicent Doñate Felip, Valtteri Hopiavuori, Max Kankainen, Mohammad Alem Khodadadi, Kauri Kolehmainen, Emma Makkonen, Liisa Nygrén, Eero Purhonen, Niklas Rolleberg, Jasmiina Tuomiranta, Tommi Vuorinen, Aurélien Mordret, Cédric Schmelzbach, Ludovic Moreau, Olivier Coutant, Céline Hadziioannou https://doi.org/10.23729/fd-05823461-d7c4-3b8d-961a-9836b46e77ec
Video supplement
Lake Ice As An Indicator Of Environmental Dynamics Marc de Langenhagen, Gregor Hillers, Tom Jilbert https://youtu.be/KPWA8vkfZjc?si=oeAO-cCCiWAMkfRA
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Summary:
This work presents a detailed overview of an impressive lake ice experiment in Finland. It probably represents the densest lake ice geophysical campaign ever deployed, with DAS, many nodes and 3 arrays of seismometers, as well as other subsurface instrumentation. The experiment and indeed the manuscript are impressive, with the manuscript providing a comprehensive overview of the dataset and initial analysis. Obviously the authors intend to work on a number of different studies beyond this work, which is of course completely fine, with this work clearly intended to act as a reference point for the dataset and preliminary analysis. The work is perhaps a little ambitious when it comes to the methane/ebullition processes and trying to observe any geophysical signature in the lake ice from trapped gases, but otherwise represents a grounded study where the analysis is supported by the observations.
My comments are minor and address minor points that do not alter the overall premise of the work. I therefore suggest that after minor revisions, this work should be suitable for publication.
General comments:
The abstract starts by stating that the experiment/study is focussed on ice properties, but then the end of the abstract introduces methane and ebullition processes. I feel the abstract would benefit from a coherent start and end, clearly communicating whether the core goals are to investigate ice properties or ice and lake processes.
The conclusions are interesting, but the links to the geochemistry analysis are barely/not mentioned at all.
The methane / greenhouse-gas framing is not supported by the results presented. The abstract and introduction suggest that the authors might try to quantify methane degassing and/or infer methane concentrations from seismic data. Yet the authors' own geochemistry shows CH4 in the ice is only ~0.01–0.1 µmol/L — a minor constituent of the trapped gas. As written, the methane-imaging goal is aspirational and is partly undercut by the paper's own data. I recommend either reframing any geochemical analysis and inferences as the potential topic of future work or presenting quantitative evidence that seismic observables here are sensitive to the gas volumes actually present.
Tomography is suggested but not performed. The title and several parts of the text imply spatially resolved imaging, but the paper reports only laterally averaged velocities/moduli plus a qualitative statement that tomography could be performed. The wording “we expect…” is used, but it is a shame that basic analysis is not followed through. The cross-correlations alone do not show a lot. This is legitimate for a data/experiment paper, but the title and abstract should be adjusted so readers are not led to expect tomography.
The data availability embargo kind of goes against the premise of the paper acting as a description of a dataset. The data-availability statement places the dataset under embargo until May 2028. Ideally, the dataset embargo would end upon publication of a broad dataset description paper like this. For a paper whose central contribution is the dataset, referees and readers cannot currently access, inspect, or reuse it, which limits reproducibility and the paper's value and impact. I can very much understand the rational behind such a decision regarding the dataset, but I do worry that it stifles the impact of this paper. Ideally, this paper would not have been submitted until when the dataset were available. At the very least, some processed data should be made available to make some of the results reproducible. I don’t think it is fair to ask for sufficient raw data to make noise cross correlations, as that could be the entire dataset, but perhaps enough data to get a flavour of noise conditions would be useful.
Specific comments:
Section 2.2 Consider condensing. It is out of balance with other sectios of the paper.
Section 3.2.4. A acoustic signal attributed partly to snowmobiles appears in the correlations. Briefly discuss whether anthropogenic sources bias the ambient-noise correlation results during the campaign.
Section 3.4 (GPR). Is the higher estimated EM velocity due to the average ice thickness used? It is important to pin down this point if you are going to make inferences about trapped gas affecting velocities.
L566 – aquatic normally suggests life/biological study of water environments. Hydrological would probably be a more appropriate word to use here.
Technical/typos:
L257: "We transfered" → "We transferred."
Need to define QS where first used (ideally define in the abstract as first used there.)
Generally define all acronyms at first use (e.g. ADR, PPSD, PSD, FK, RTK DGPS).