the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Assessment and comparison of thermal stabilisation measures at an Alpine permafrost site, Switzerland
Abstract. Global warming provokes permafrost thawing, which leads to landscape changes and infrastructure damage, problems that have intensified worldwide in all permafrost regions. This study numerically investigates the impact of different thermal stabilization methods to prevent or delay permafrost thawing. To test different technical methods, an alpine mountain permafrost site with nearby infrastructure prone to damage is investigated. Model simulations represent the one-dimensional effect of heat fluxes across the complex system of snow-ice-permafrost layers, and the impact of passive and active cooling, including engineered energy flux dynamics at the surface. Results show the efficiency of different passive, active, and combined thermal stabilisation methods, in influencing heat transfer, temperature distribution, and the seasonal active layer thickness. Investigating each component of thermal stabilization helps quantify the efficiency of each method and determine their optimal combination. Passive methods despite provide efficient cooling in winter, due to heat transfer to the atmosphere, are less efficient as the active layer thickness remains over 1 m. Conductive heat flux regulation alone takes several years to form a stable frozen layer. Active, when powered with solar energy, cooling decreases the active layer thickness to a few decimetres. The combination of active and passive cooling, together with conductive heat flux regulation, performs best and allows excess energy to be fed into the local grid. Findings of this study show ground temperature and permafrost evolution at a representative alpine site under natural and thermally stabilized conditions, contributing to understanding potential and limitations of stabilization systems and formulate recommendations for optimal application.
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Status: open (until 27 Mar 2025)
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RC1: 'Comment on egusphere-2024-4174', Anonymous Referee #1, 06 Feb 2025
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General comments:
The manuscript is well-documented, providing a solid review of the state of the art. It addresses an interesting topic with a novel approach and is highly relevant to the current state of research in this field. However, at times, the manuscript becomes difficult to read due to the large amount of information presented, which is not always structured in a way that facilitates comprehension. A clear example of this is the first paragraph of the Results section, where the authors themselves include a clarification that should not be necessary if the text were more effectively organized.
In addition, the Results and Discussion section would benefit from a deeper discussion, as it sometimes feels like the authors are merely describing the experimental results rather than engaging in a more analytical interpretation. Furthermore, the manuscript lacks comparisons with similar studies or references that would help position this work within the broader context of the field.
There are also several typos and some unclear sentence constructions that should be reviewed. While I will highlight some specific instances in the Technical Corrections section, I strongly recommend a thorough proofreading of the manuscript to improve clarity and readability.Finally, some parts of the Conclusions section would be better placed in the Discussion, as they would strengthen the interpretative aspects of the study while also improving the clarity of the Conclusions, which currently feel somewhat long and not very straightforward.
Overall, I would like to congratulate the authors on their work and hope that they will consider the comments and suggestions provided to further improve the manuscript.Specific comments:
L190: The observational permafrost temperature and atmospheric data sets of this site are largely sufficient -> “largely” based on what?
L219: The simulations have been run from June 2000 to January 2017-> Why this period? Explain, please.
L220: …an hourly time step-> Why hourly? Explain, please.
L265: The objective of this experiment is to allow more efficient… -> Is that really the objective? It is not to analyze the applicability?
L268: We simulate the presence of a 50-100 mm thick… -> Why that thickness and not a different one? Explain, please.
L273: The albedo of the isolation material is assumed to be 70%... -> 70% based on what? Explain, please.
L299: …as evident in Equation (1).-> Not sure that “evident” is the right choice. If something is evident, there is no need to say it.
L329: For some periods, measured snow depth is below the simulated one indicating that the model would underestimate melt or erosion.-> What is the reason for this? Can you support this statement with a reference?
L527: No corrections here, I just wanted to say that, in my opinion, it is a really great paragraph.
Figures:
Maybe this is something on my side, but it is not clear to me why in some figures you choose daily averaged ground temperatures while in others you choose monthly averaged values.
In most of the figures, it is really difficult to distinguish the numbers within the blue color areas.
In Figure 1 I miss some location references (lat, lon or UTM).Technical corrections:
L31: Review the citing style-> I think this should be the correct one: (Hauck, 2002; Swiss Permafrost Monitoring Network (PERMOS), 2024).
L38: Review the citing style, same problem.
L48: Review the citing style, same problem.
L108: Review the citing style -> order?
L111: Review the citing style-> year?
L132: Review the citing style -> order?
L132-136: Repetitive use of “include”.
L153: When the ground temperatures reaches set threshold, the cooling system turns off, in the model it means is activated -> This sentence makes no sense, there is something missing or maybe the structure is wrong.
L204: Review the citing style -> order?
L212: The geological map (..) indicates a limestone bedrock on this site in depth and the with sandy… -> This sentence makes no sense, there is something missing here or maybe the structure is wrong.
L290: Thelatter are modelled by implementing an sink term…-> There is something wrong here.
L332-3: Repetitive use of “layers”.
L334-5: Repetitive and confusing use of “ALT”.
Figure 2: Redundant information (0°C isotherm).
Figure A2: Redundant 2000 to 2017.
Figure B2: Redundant 50 mm to 100 mm.
L637: Reference incomplete.Citation: https://doi.org/10.5194/egusphere-2024-4174-RC1
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