The number and elevation of sensors in dense and loose sand samples are inconsistent. For valid comparison, sensors should be placed at the same elevations and in equal numbers across both sample types. Please clarify the rationale for the current setup.

In Figure 6, direct comparisons are made between samples with different sensor positions, which can affect the validity of the results. It is recommended to justify this approach clearly, or revise the figure and analysis to focus on results from consistent sensor locations, discussing the potential impacts of any inconsistencies.

Physical testing in geotechnical and permafrost engineering holds substantial promise for advancing our understanding of complex subsurface processes. Laboratory-based physical modeling, especially under controlled conditions such as hypergravity, enables researchers and engineers to simulate and observe phenomena that are otherwise challenging to capture in the field under controlled conditions. Such testing provides invaluable data for validating analytical and numerical models, refining theoretical frameworks, and informing practical engineering solutions. The manuscript by Gardner et al. leverages these strengths and presents results that are very interesting to the readership of this journal. They really highlight the potential of hypergravity testing in cold regions engineering., However, several aspects of the manuscript could be improved to enhance clarity, rigor, and overall impact.

The study presents an approach to investigating thawing rates in frozen sand using hypergravity. The uniform conditions established in the experiments offer an ideal setting for comparison with established analytical solutions, such as the Stephen equation and the modified Berggren equation. Incorporating a more detailed discussion on a comparison between model and analytical results would significantly strengthen the manuscript and add value for readers. Additionally, further elaboration on the impact of insulation—particularly at the bottom of the samples—would provide deeper insights into how to avoid boundary effects in future physical models.

In general, the manuscript is well written and relevant references cited. The following lists additional specific comments the authors are encouraged to address:

• Abstract: The manuscript refers to active layer thicknesses of “10s of meters.” This is not realistic; while 10 – 15 m may be possible in bedrock, the development observed is typically that of a supra-permafrost talik where the frost depth no longer reaches the permafrost table.
• Line 9: When introducing permafrost, it is recommended to use the latest definition published by the CPA (Lewkowicz et al., 2025). While the current definition is not incorrect, adopting the most recent terminology is encouraged.
• Line 15: The use of the term “diseases” in reference to permafrost thawing is discouraged. Although this terminology is sometimes used by colleagues in Chinese literature, permafrost degradation should be described as a hazard, danger, or risk, rather than a disease.
• Line 38: The manuscript alternates between “field scale” and “prototype scale.” It is recommended to unify this terminology throughout the text for consistency.
• Line 41: In discussing the experimental configuration, the authors should emphasize the importance of heat fluxes rather than absolute temperature values. Ensuring consistent and uniform heat flow direction that are representative for porotype conditions is critical in physical modeling.
• Lines 45–46: The manuscript notes that freezing and thawing should occur in a one-dimensional manner to eliminate three-dimensional effects.
• Please verify and clarify the first sentence on line 61, as it appears incomplete.
• Line 81: The scaling for heat conduction is provided, but the scaling for phase change (freezing and thawing) is not addressed. Please elaborate on how phase change is reacting to hypergravity.
• Line 87 and Throughout: The term “thaw” should be used consistently throughout the manuscript, rather than “melting,” as permafrost undergoes thawing, not melting.
• Figure 3: It is recommended to add scales, annotate and label thicknesses of insulation and sample heights to improve clarity.
• Figure 5: Please provide an explanation for the observed steps in thaw penetration and why the process does not proceed gradually. Additionally, consider adding a figure showing thaw depth versus time for both insulated and un-insulated tests.
• Figure 5 and Related Discussion: The data indicate that thawing occurs from the bottom up, suggesting that the process is more complex than a purely one-dimensional problem. The manuscript should discuss the implications of this finding and the role of heat flow within the samples.
• Section 5: As previously mentioned, a comparison with analytical solutions such as the Stephen or modified Berggren equations would add significant value when discussing thaw penetration.