Long-Term Variability in Ground Thermal State in Central Yakutia’s Tuymaada Valley

Round 1

Reviewer 1 Report

Overall comments:

The authors use the phrasing “statistically significant” multiple times. The r-squared value is not an adequate measure of statistical significance. Before publication of this manuscript, it is necessary to include tests for statistical significance if the authors want to continue using this language. I strongly suggest that the trends need to be tested for statistical significance using adequate methods.

Largely the method section lacks detail. Methods like the Stefan problem show up for the first time in the results section and are not adequately described. Methods need to be introduced previous to the result section.

 

Specific comments:

Line 25 – 33 : a lack of references

Figure 1: Please expand the figure caption to include the data source and specify the type of measurements (air temp vs ground temp)

Figure 1 and 2 are not mentioned in the text

Figure 4 and 5 need a scale and should be located on Figure 8

Figure 6 is not mentioned in the text

Figure 8 is not mentioned in the text

Line 239 – 259 belong in the methods section as does a lot of the results section in general

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments to the Authors

The paper by Varlamov et al. investigates long-term variability in soil temperature in the central Yakutsk. The authors appear to have an expensive dataset and results from the analysis could potentially be of interest to the broader permafrost community. However, the paper is not well written and the overall objectives and the research contributions are unclear. In my view there is much work required to prepare a paper that would be acceptable for publication.

The objective stated at the end of the introduction is “The main purpose of this article is to assess the spatiotemporal variability of the thermal state of soils in intrazonal (valley) landscapes”. For the most part this is a reasonable objective and my expectation was that the authors would present information on the ground thermal regime from various landscape types and consider the variability in response of the ground thermal regime to climate change between the various landscape types. The authors seem to be focussing on 3 stations and present data and analysis from each but there is no consistency regarding the analysis between the 3 stations (for example, why are energy balance components characterized only for some of the stations or the “Stefan equation solved” for one station). It is also not clear to me that there has been an attempt to bring the results from the 3 stations together to make conclusions regarding the different influences on the response of the ground thermal regime associated with different landscape types. The authors need to have a clear objective and then choose the sites having adequate data to address the objective. If the goal is to compare the response of the ground thermal regime for the range of landscape types in the region then choose representative landscape types (this might include both natural and disturbed areas). This choice will depend on the type of data required to meet the objective which may not exist at all sites. For example, do your require time series for a specific period for ground temperature (e.g. a similar approach to that in Fig. 11and 12 and consider other vegetation/land surface types including disturbed sites and consider relation between trends in ground temperature and air temperature etc); is on site climate data required; is there adequate information on soil conditions. This may mean some of your sites may not be used in the analysis. A more regional approach is probably required rather than a detailed examination of individual stations.

The paper would benefit from clearly describing methodology in only one section. There is a methods section but there is some information on methods mixed into the results section. It would also be beneficial to split the “Results and Discussion” section into two sections and discuss results first and the interpretation in the discussion section. This will make it clear which results are new rather than those that appear to come from previous research. Background information should be kept to minimum. Some background information is required to set the stage for the research and to place it in the context of previous studies. However, there is quite a bit of background information in other sections of the paper that might not be necessary.

There have been studies in other Arctic permafrost regions outside of Russia (e.g Northern Canada, Alaska, Nordic regions) which consider trends in permafrost temperature or the permafrost-climate relations for various terrain/vegetation types. A few that come immediately to mind include Throop et al. (2012); Strand et al. (2021); Romanovsky et al. (2020); Etzelmuller et al. (2020); Morse et al. (2016); Kokelj et al. 2017. It would be useful to compare results from other region to better place your research in the context of this broader research. Is there something different with respect to your studies; are the results similar etc.

In summary, the paper needs to be better organized with objectives clearly identified and a clear presentation of the results and interpretations to validate any conclusions made. The authors might also find it beneficial to engage someone to edit the manuscript to improve both language and clarity.

References cited above:

Etzelmüller, B. et al. 2020Twenty years of European mountain permafrost dynamics—the PACE legacy. Environ. Res. Lett. 15, 104070 https://doi.org/10.1088/1748-9326/abae9d

Kokelj SV, Palmer MJ, Lantz TC, Burn CR (2017) Ground temperatures and permafrost warming from forest to tundra, Tuktoyaktuk Coastlands and Anderson Plain, NWT, Canada. Permafrost and Periglacial Processes 28:543-551. doi:10.1002/ppp.1934

Morse, PD et al. 2016. The Occurrence and Thermal Disequilibrium State of Permafrost in Forest Ecotopes of the Great Slave Region, Northwest Territories, Canada. Permafrost and Periglacial Processes 27 (2): 145-162. DOI: 10.1002/ppp.1858

Romanovsky VE, Smith SL, Isaksen K, Nyland KE, Kholodov AL, Shiklomanov NI, Streletskiy DA, Farquharson LM, Drozdov DS, Malkova GV, Christiansen HH (2020) [Arctic] Terrestrial Permafrost [in "State of the Climate in 2019"]. Bulletin of the American Meteorological Society (supplement) 101 (8):S265-S269. doi:10.1175/BAMS-D-20-0086.1

Strand, S. M., Christiansen, H. H., Johansson, M., Åkerman, J. & Humlum, O. 2021. Active layer thickening and controls on interannual variability in the Nordic Arctic compared to the circum-­Arctic. Permafrost and Periglac Process 32, 47–58. DOI: 10.1002/ppp.2088

Throop J, Lewkowicz AG, Smith SL (2012) Climate and ground temperature relations at sites across the continuous and discontinuous permafrost zones, northern Canada. Canadian Journal of Earth Sciences 49:865-876. doi:10.1139/E11-075

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

I believe the authors did a a great job incorporating the reviewers comments and the paper is significantly improved.

Author Response

Thanks for the comments made, they have all been eliminated.