the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 14 Oct 2025
Thermo-hydrological observatory in a permafrost river valley landscape in Syrdakh, Central Yakutia
Abstract. Permafrost thaw affects the global carbon cycle and can significantly alter landscape morphology and associated processes of mass and energy transfer. An understudied aspect of affected permafrost landscapes are ubiquitous rivers connecting thermokarst lakes. These ubiquitous features of Arctic landscapes exhibit particularly high variability in water and energy transfer, and thus provide an excellent field laboratory for analyzing how expected changes in meteorological forcing under climate change affect permafrost dynamics and carbon exchange within the land- and limnoscape. This paper presents a database from 2012 through 2022 for one such small stream connecting two thermokarst lakes. First, two main stream cross sections were instrumented with multiple thermistor chains to record temperature evolution from the surface to different soil depths. The cross sections covered different topography and vegetation cover. One was located near the upper, and one in between the two thermokarst lakes. The main focus was set on the cross section midway between the two lakes due to the absence of a thermal imprint from the lake. Air, water, and ground temperatures, as well as river water parameters, and soil properties of the surrounding environment were measured as time series or single tests during annual field campaigns. The data are organized in three main categories: atmosphere, water and ground, and are complemented by a GIS including a digital surface model and an ortho-mosaic photo of the entire river valley to facilitate the search for measurements of interest. The database comes with a complete set of scripts to process any of the data, which are provided in CSV or other easily accessible standard file formats. Ultimately, the data can be used to develop models and validate numerical codes for improving the representation of permafrost processes in land surface and climate models where climate change induces significant changes in heat and mass transfer. All data and processing scripts are available through an online repository (https://doi.org/10.5281/zenodo.14619854; Pohl et al. (2025)).
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Status: open (until 17 Dec 2025)
- RC1: 'Comment on essd-2025-134', Anonymous Referee #1, 12 Nov 2025 reply
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RC2: 'Comment on essd-2025-134', Gonçalo Vieira, 08 Dec 2025
reply
The manuscript describes a rich dataset from multiple environmental parameters collected in a study area located between two lakes connected by a stream in a permafrost area in Central Yakutia. Despite the small size of the study area, its geomorphological and hydrological setting, together the rich set of variables measured makes this data set of high scientific value for studying the dynamics of permafrost environments.
The manuscript is well-written and the dataset is presented in a generally clear way. It is associated to a rich dataset, which has several gaps and also some problems due to changes in instruments and techniques, with large uncertainty in some variables. However, given the harsh environmental conditions and timespan of the measures, this could be expected, and most key data is highly relevant. The authors decided to make all data available and this is of high value.
Overall, I missed a better description of the geographical setting of the study site. Actually, it was only after reading the whole document and when inspecting the Zenodo dataset, that I found a clear picture that encompasses the landscape setting. It is an oblique aerial picture that you should include in the body of the manuscript as support for the site description. An inspection of Bing virtual earth imagery of the area shows the remarkable landscape setting with thermokarst lakes, but this is almost entirely missed in the manuscript. A better description of the geographical framework accompanied by illustrations would increase the potential interest and usage of the dataset.
In what concerns to the dataset in Zenodo, one important issue is the lack of the QGIS project file that should allow to open all geographical data. This is important and needs to be made available for review and for final acceptance of the manuscript.
Besides these more general comments, below you may find a list of edits and some comments to be addressed by the authors.
Title: "Thermo-hydrological observatory in a permafrost river valley landscape in Syrdakh, Central Yakutia". Consider mentioning Yedoma in the title and add the period of observations.
Line 78. Describe the thermokarst lakes, as their characteristics are relevant to the hydrological dynamics of the stream. A better description of the catchment is also needed.
Line 95. The name Quantum GIS was abandoned and the software is named QGIS.
Line 96. "at various depth" should be "at various depths".
line 101. 3.2 "Data location" should better read as "Location of observations" or "Location of observation points". Consider improving this subsection title.
Line 102-115. Section 3.2. The problems with the position of the data collection points are not clearly explained. Make it clearer as a correct understanding of the positioning is essential. Consider presenting the non-corrected (or original) coordinates, as well as the corrected geographical coordinates. As it is, it is not straightforward to understand the problems.
Line 123: Rather than presenting this as an equation, it should be referenced as the file name structure.
Line 128: Modify order: L0, L1, L2
Line 134. It is not an equation.
Line 134. Metadata and not meta-data
Lines 144-145. "Monotonous temperature shifts": does that this mean monotonic? Clarify the sentence. Do you mean isolated peaks? always n=1?
Line 155. Indicate and explain the time-intervals of the measurements, as in Table 1, which is not very clear, there are measurements with intervals from 1h to 1 year.
Line 160: Indicate all measurement depths in the thermistor chains as well as the installation setup (boreholes, or other; type of casing, casing diameter, infill medium)
Lines 198-199: Rephrase in order to clarify: "The calculation of thermal properties of the KD2 Pro device might have high uncertainties. This is because significant differences in some cases between the also utilized Anritsu thermometer are apparent".
Lines 214-217: The subsection is titled boreholes and piezometer tubes, but it does not contain information about the borehole setting nor piezometer tubes. Check the text and add information about these.
Line 220: "Upper thawed layer depths" should rather be "when thaw propagation was maximum"
Line 229: 71.5 m
Line 276: "Deviations from the reporting classes exist." Please clarify what this means. The reader figures that the Malvern is used after 2017, but still the "deviations" part needs to be clarified.
Line 324 - Correct typo "unceertainty".
Line 331 - Indicate if a solar radiation shield was used and type. From a photo in the dataset I see a logger attached to a tree. In what way does it affect temperatures? What is the aspect? Does it stay shadowed all year? These need to be addressed.
Lines 331-332 - Why do you make reference to section 4.3.1?
Line 333 - Indicate the distance of the Yakutsk meteorological station.
lines 336-337 - Rephrase. The reference to "reasonable representation of air temperatures" is subjective. You may mention that the high coefficient of determination supports the good quality of the data and the regional climate signal's influence on local conditions at the study site.
Line 378 - Correct "a coefficient"
Line 437: Indicate if it is WGS84 UTM Zone 52N or other datum.
Line 441: You mention the use of GCPs in 2021, but please indicate the accuracy. It is also important to know the image overlap in the flight, as well as flight height, if available. In the following subsection you mention a 0.5m absolute accuracy. Is this horizontal? What about vertical? How was the correction made, as 0.5m is really a large positional error.
Line 448. You mention Leica Viva Uno 10 (GPS+GNSS). Do you mean GPS+GLONASS?
Line 453. See comment for lines 110-115.
Figures and Tables
Figure 1. A map is needed showing the framework of the site, especially showing the two lakes and the general landscape features.
Figure 3 - The depths from the sensor names do not correspond to the boundaries in the Y axis.
Table 1 is very complete but the font size is too small for reading. Consider improving it. Measuring intervals are not clearly understandable from the table. They should be readable according to instrument types horizontally.
Zenodo dataset
- The QGIS project file syrdakh_gis_2025-06-10.qgz is not in the dataset and needs to be included.
- DEM: Actually it is a DSM and not a DEM as correctly described in the manuscript, but the file (and those mentioning a DEM) must be named accordingly. I also recommend masking the DSM using the boundaries of the Orthomosaic, as there are large parts of the DEM that are just noise and should be removed. If the data is to be used by modelers, then the DEM should include only the area with good data (despite the other severe limitations with slope that are mentioned in the manuscript). A good way to make this data useful, especially given the poor GCPs in the terrain, would be to make all aerial photos available in the Zenodo dataset. This would allow for future reprocessing.
Citation: https://doi.org/10.5194/essd-2025-134-RC2
Data sets
Thermo-hydrological observatory in a permafrost river valley landscape in Syrdakh, Central Yakutia E. Pohl et al. https://doi.org/10.5281/zenodo.14619854
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- 1
Review of Thermo-hydrological observatory in a permafrost river valley landscape in Syrdakh, Central Yakutia by Pohl et al. for Earth System Science Data
General overview:
This is an exhaustive dataset of a variety of commonly used measurements to characterize permafrost in an area where it is changing rapidly. Overall, it is well written and the explanations are ample to be able to repeat the measurements. In a few locations I suggest further information/clarification. This paper will be of interest to other permafrost scientists but also provides a strong example of how to design a long-term field experiment and name and organize a disparate dataset. The dataset is unique, useful, and complete. The abstract and introduction use carbon as a main motivation to measure/study permafros.t However, I would argue that other biogeochemical parameters, hydrologic changes, and of particular interest infrastructure (linear and horizontal) are also affected by permafrost degradation. Many of the measurements provided could be used to instrument buildings, bridges, airfields, or roads to identify change. Mentioning these additional reasons to study permafrost would strengthen the impact and relevance of the work.
The tense bounces around a lot. For example, around line 254 “were conducted”, at 257: “is provided”, 262: “are based”, 267: “was used” and throughout. Maybe this works to bounce around like this but it is worth making sure it is as consistent as possible.
Comments keyed to the text:
2: permafrost-affected
3: use a different word so as to not use “ubiquitous” twice in a row. Or remove second instance- not needed
7: provide total depth here
10: what parameters?
12: GIS database
37: define “thermokarst lakes” here- what are they and how do they form? What do they represent?
42: put talik definition in parentheses instead of using the “i.e.”
49: is “Yedoma Permafrost Domain” a real name?
I recommend providing a sentence identifying/defining yedoma as high ice content, high carbon and organic matter content permafrost comprised of fine-grained soils and that due to these characteristics state that yedoma is particularly susceptible to thermokarst formation. This is currently mostly provided at 66-69 but is better to move here.
Provide general latitude and longitude here.
73: you defined taliks earlier
80: reference for these protocols?
86: in addition, the focus
88: was installed
109: and creating
110: depths and velocities
Table 1. This is a great list of measurements! Font is extremely small though. Perhaps make it landscape to provide room for a larger font?
Is there a day/date associated with the thaw depth measurements to discern between seasonal thaw and active layer?
Maybe break the active layer/thaw dataset into two since it is important to know whether it is a true active layer or just seasonal thaw at a given moment tin time. At the least the “aclt” label is misleading if it means “active layer thickness.”
Figure 1. I recommend splitting this into a few Figures either here or in an appendix.
Red labels in B are unreadable
Maybe keep A and B as is (Figure 1) but without larger labels on B and then provide C and D as Figures 2 and 3.
155-161: any information on how these installations were done? Maybe a schematic cross section? Or a description? For the HOBO loggers the borehole diameter and construction?
Figure 3. State that the depths of these thermistors are provided as, for example “300” (which I assume means 300 cm).
203-207: are there any “true” active layer depths in the area to compare to?
Figure 5. Also provide some of these measurements over time for given locations to look for trends? Maybe the different ties/dates in September make this not worth doing? Would be good to at least provide the plot and some discussion.
Or a separate plot of just “true” active layer values (presumably you have this for at least 2017 and 2028, maybe other years?).
235-242: This seems to be in the wrong place. It is not related to the ERT.
307: the true active layer or seasonable thaw at that time?
361: “do not derive significantly”- not sure what this means. Do not drift?
366: “do not derive significantly”- not sure what this means. Do not drift?
Figure 14. Provide “north and south” or whatever directions work for this cross section (i.e. the -1000 and 1000).
433: “do not derive significantly”- not sure what this means. Do not drift?
Appendices provide wonderful photos of field site activities and measurements.